CN101055740B - Optical information recording medium - Google Patents

Optical information recording medium Download PDF

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Publication number
CN101055740B
CN101055740B CN2007100896279A CN200710089627A CN101055740B CN 101055740 B CN101055740 B CN 101055740B CN 2007100896279 A CN2007100896279 A CN 2007100896279A CN 200710089627 A CN200710089627 A CN 200710089627A CN 101055740 B CN101055740 B CN 101055740B
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recording
spot
record
recording layer
medium
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CN101055740A (en
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水野裕宣
大野孝志
堀江通和
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Mitsubishi Chemical Corp
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Mitsubishi Chemical Corp
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Abstract

The invention provides a medium for recording optical information, at least comprising a phase change recording layer at a substrate. Crystalline state part is taken as an unrecorded and erasing status and amorphous part is taken as a record status and information is recorded by making use of a plurality of record mark lengths with shortest mark length less than 0.5 Mum. A medium for recording optical information, which is characterized in that crystal growth beginning at the borderline between the amorphous part or melting part and the surrounding crystalline state, actually re-crystallization, is made use of to carry out erasing, and an optical recording method applicable to the medium are disclosed. The medium of the invention can rewrite at high speed, has small mark borderline jitter and can carry out high density mark length regulation record and the formed mark is well stable for a long period.

Description

Optic informating recording medium
The application is that denomination of invention is " optic informating recording medium and optic recording method ", the applying date to be dividing an application of September 8, application number in 1999 female case that is 99801637.3 (PCT/JP99/04874).
Technical field
The present invention relates to high density recording that erasable DVD etc. has a phase change type recording layer with optical recording media and optic recording method, when particularly single beam rewrites with the relation of linear velocity and with the relation of recording power with write down improved optical recording of spot long-time stability and optic recording method.
Background technology
Usually, compact disk (CD) and DVD are that the reflectance varies that is used to produce from the catoptrical interference of pit bottom and minute surface part is carried out the record of 2 value signals and the detection of tracking signal.
In recent years, be extensive use of the erasable compact disk of inversion of phases (CD-RW, CD-Rewritable) as the medium of interchangeability being arranged with CD.In addition, about DVD, the scheme of the erasable DVD of various inversion of phases is proposed also.
Erasable CD of these inversion of phases and DVD utilize the difference of amorphous state and crystalline state refractive index and the reflection differences and the phase differential that produce change the detection of carrying out recording information signal.Common inversion of phases medium have the structure that bottom protective seam, phase change type recording layer, upper protective layer and reflection horizon are set on substrate, utilize the multiple interference of these layers, and control reflection differences and phase differential can make it have interchangeability with CD and DVD.
In CD-RW, reflectivity is reduced in the scope of 15-25%, can guarantee tracer signal and the groove signal and interchangeability CD, utilize the additional CD driver of covering up the low amplification system of reflectivity, just can reset.
In addition, the phase-change recording medium are because the process that only just can wipe with the light intensity modulation of monofocal light beam and write down, therefore in phase-change recording medium such as CD-RW and erasable DVD, so-called record comprises the regenerative recording that writes down simultaneously and wipe.
When utilizing phase transformation to carry out the information record, can adopt crystalline state, amorphous state or their mixed state, also can adopt a plurality of crystallization phases, but the erasable phase-change recording medium of present practicability, normally not record and erase status are adopted crystalline state, and carry out record by forming amorphous spot.Often adopt as the material of recording layer and to contain chalcogen, promptly the chalcogenide of S, Se or Te is an alloy.
For example have with GeTe-Sb 2Te 3Pseudobinary alloy be the SeSbTe of principal ingredient be alloy, with InTe-Sb 2Te 3Pseudobinary alloy be the InSbTe of principal ingredient be alloy, with Sb 0.7Te 0.3Eutectic is that the AgSbTe system of principal ingredient closes and GeSnTe system etc.
Wherein, main practicability is that Sb with surplus makes an addition to GeTe-Sb 2Te 3Pseudobinary alloy and the alloy system, particularly Ge that form 1Sb 2Te 4Or Ge 2Sb 2Te 5Deng the contiguous composition of intermetallic compound.
These are formed owing to have the distinctive feature of not following the crystallization that is separated of intermetallic compound, and rate of crystalline growth is fast, so initialization is easy, and crystallization rate is fast again when wiping.So pseudobinary alloy system and intermetallic compound always all are subjected to closing (document Jpn.J.Appl.Phys. contiguous the composition as demonstrating the recording layer of the rewriting characteristic with practicality, Vol.69 (1991), p2849, or SPIE, Vol.2514 (1995), pp294-301 etc.).
But on the other hand, in these are formed, the crystal grain of the metastable tetragonal crystal system of also having grown.Because the crystal boundary of this crystal grain is clear and definite, and not of uniform size causing,, therefore there is problems such as being easy to generate the optics white noise because of its position presents significant optical anisotropy to difference.
And therefore the growth around the amorphous state spot easily of the different crystal grain of such particle diameter and optical characteristics increases beating of spot easily, perhaps because different with the optical characteristics of crystal on every side, easily as not cleaning and being detected.
Therefore, in the record or highdensity spot length modulated record of high linear speed, existence can not obtain the problem of good reproducing characteristics.Specifically, in the standard of erasable DVD, the shortest spot length is 0.6 μ m, if the shortest spot length is shortened again, then clearly, beating sharply to increase.
As the method that improvement is beated, so-called absorptivity penalty method is arranged.In 4 layers of structure in the past, in the luminous energy that common recording layer absorbs, the luminous energy Aa that the luminous energy Ac that the crystalline state that reflectivity is high absorbs absorbs less than the low amorphous state of reflectivity (Ac<Aa).Have such problem to produce when therefore rewriteeing, the meetings such as shape of promptly new record spot are that crystalline state or amorphous state change because of original state, and increase causes beating.
In this case, be to make crystalline state and amorphous luminous energy absorption efficiency about equally, no matter how spot shape is stable for original state, reduce beat (jitter) like this.Add,, wish that therefore crystalline state absorbs more luminous energy (Ac〉Aa) because crystal also needs this part heat of latent heat in addition when fusion.
In order to realize this relation, it is to increase one deck light absorbing zone at least that a kind of method is arranged, and forms the structure more than 5 layers, absorbs the part of amorphous light absorption with this absorption layer.For example, and absorption layers such as insertion An or Si between bottom protective seam and substrate or on upper protective layer (Jpn.J.Appl.Phys., Vol.37 (1998), pp33393342, Jpn.J.Appl.Phys., Vol36 (1988), pp2516-2520).
But such layer structure exists the thermotolerance and the adhesive problem of absorption layer, if rewrite repeatedly, then deterioration condition such as the distortion of microcosmic and record stripping is remarkable.And, owing to be easy to generate situation such as peel off, also damage long-time stability.
That is to say, keep 4 layers of structure in the past again, reach high density again, adopt GeTe-Sb 2Te 3The pseudobinary alloy recording layer is to be difficult to realize.
And, if use GeTe-Sb 2Te 3The pseudobinary alloy recording layer, wavelength is short, and the real part of its complex index is more little, and imaginary part is big more, promptly has the dependence with wavelength.When particularly using short wavelength laser, be difficult to reach Ac as light source〉condition of Aa.
Therefore in recent years, just using AgInSnTe quaternary element alloy as recording layer material.The feature of AgInSbTe quaternary element alloy is can obtain wiping ratio up to the height of 40dB, with 4 layers of structure in the past, does not carry out the absorptivity compensation, just can carry out highdensity spot length modulated record with high linear speed.
But what is called can be carried out high-speed record, means that usually crystallization speed is fast, wipes easily.Therefore also crystallization easily of amorphous state spot often, the long-time stability of record spot are poor.
In recent years, quantity of information increases, and in order to shorten writing time and to improve the rate of information throughput, needs to carry out with more speed the medium of record reproducing recently.For example, the standard speed of CD (1 times of speed) is 1.2-1.4m/s, and the CD-RW commercialization that can write down with 4 times of speed, and require to have can be with 8 times of speed, 10 times of CD-RW that speed writes down.
In addition, as erasable DVD, propose or realized the commercial DVD-RAM of having, DVD+RW, DVD-RW etc.But, also do not have practicability with the erasable DVD of the 4.7GB of read-only DVD same capability.
That is to say that needing can be with the medium of short spot of high-speed record and spot good stability.
But, thought in the past that high-speed record and spot stability were the characteristics of contradiction, be difficult to satisfy simultaneously the characteristic requirement of this two aspect.
The present inventor studies with regard to crystallization and decrystallized principle repeatedly, and the result finds the epoch-making medium that satisfy all these characteristics simultaneously.
That is to say, the object of the present invention is to provide a kind of optic recording method that can at full speed write down the optical recording media that short spot and spot have good stability preferably and be fit to this optical recording media.
Summary of the invention
The 1st main points of the present invention are a kind of optic informating recording mediums, and described optic informating recording medium has phase change type recording layer and reflection horizon at least on substrate,
As not writing down and erase status, as recording status, utilizing the shortest spot length is that the following multiple record spot length of 0.5 μ m is come recorded information with amorphous portion with the crystalline state part,
Utilization from amorphous state partly or the crystallization again in fact carried out of puddle and the crystal growth that begins of crystalline state portion boundary on every side wipe, the reflection horizon thickness is below the above 300nm of 40nm, specific insulation is below the above 150n Ω of the 20n Ω m m.
The 2nd main points of the present invention are a kind of optic informating recording mediums, and it is the phase change type recording layer and the reflection horizon of the film formation of principal ingredient that described optic informating recording medium has on substrate with Ge, Sb, Te,
As not record and erase status, as recording status, utilize the many record spot length below the shortest spot length 0.5 μ m to come recorded information amorphous portion the crystalline state of this recording layer part,
These medium can basic crystallization under the recording light Continuous irradiation of the recording power Pw that is enough to make the recording layer fusion with certain linear velocity,
And in case cut off shining the back in the recording light of the recording power Pw that is enough to make the recording layer fusion, then form the amorphous state spot with certain linear velocity, and the reflection horizon thickness is below the above 300nm of 40nm, specific insulation is below the above 150n Ω of the 20n Ω m m.
The 3rd main points of the present invention are a kind of optic informating recording mediums, and described optic informating recording medium is according to the incident direction from recording playback light the 1st protective seam, phase change type recording layer, the 2nd protective seam and reflection horizon to be set in regular turn to constitute on substrate,
As not record and erase status, as recording status, utilizing the shortest spot length is that multiple record spot length below the 0.5 μ m is come recorded information with amorphous portion with the crystalline state of this recording layer part,
The phase-change recording layer thickness is below the above 25nm of 5nm, is that the film of principal ingredient constitutes by having the GeSbTe alloy of forming in following zone, and described zone is in the GeSbTe ternary state diagram, uses
Connect (Sb 0.7Te 0.3) with the straight line A of Ge,
Connect (Ge 0.03Sb 0.68Te 0.29) and (Sb 0.95Ge 0.05) straight line B,
Connect (Sb 0.9Ge 0.1) and (Te 0.9Ge 0.1) straight line C and
Connect (Sb 0.8Te 0.2) with the straight line D of Ge
Deng 4 straight line area surrounded (but not comprising on the boundary line),
The 2nd protective seam thickness is below the above 30nm of 5nm, wherein,
The reflection horizon thickness is below the above 300nm of 40nm, and specific insulation is below the above 150n Ω of the 20n Ω m m.
Another main points of the present invention are to be suitable for the desirable optic recording method that uses with above-mentioned medium.
Description of drawings
Figure 1 shows that one of amorphous state spot shape example.
Figure 2 shows that the reflectance varies figure when one of medium of the present invention example writes down.
Fig. 3 is the GeSbTe ternary state diagram of the compositing range of the recording layer of expression medium of the present invention.
Fig. 4 is the GeSbTe ternary state diagram of the existing GeSbTe compositing range of expression.
Fig. 5 is the synoptic diagram of one of the layer structure of expression medium of the present invention example.
Fig. 6 is the signal waveforms that concerns usefulness of expression signal intensity and signal amplitude and degree of modulation.
Fig. 7 is the curve map of the dependence of explanation reflectivity and the 1st protective seam thickness.
Figure 8 shows that one of the pulse dividing method example of power 3 values modulation recording mode.
Fig. 9 is the time dependent synoptic diagram of declare record layer temperature.
Figure 10 shows that one of the pulse dividing method example of the power 3 values accent recording mode that is suitable for spot length modulated record.
Figure 11 realizes the concept map of 3 kinds of gate signal generation circuit sequences that the pulse dividing method of Figure 10 is used for explanation.
Figure 12 shows that the dependence curve map of beating in embodiment 1 and the comparative example 1 with the playback luminous power.
Figure 13 shows that the curve map of beating among the embodiment 1 with the dependence of recording impulse dividing method.
Figure 14 shows that the curve map of beating among the embodiment 1 with the dependence of recording impulse dividing method.
Figure 15 shows that among the embodiment 2 beat, the curve map of the dependence of reflectivity and degree of modulation and recording power.
Figure 16 shows that among the embodiment 2 beat, reflectivity and degree of modulation and the curve map of the dependence of number of rewrites repeatedly.
Figure 17 shows that the curve map of beating among embodiment 2 (g1) and the embodiment 2 (d2) with the dependence of spot length.
Figure 18 shows that the curve map of beating among the embodiment 2 with the dependence at substrate inclination angle.
Figure 19 shows that beating and α after 10 rewritings among the embodiment 4 iAnd α cThe curve map of dependence.
Figure 20 shows that among the embodiment 4 beat, Rtop and degree of modulation and the curve map of the dependence of number of rewrites repeatedly.
Figure 21 (a) is depicted as the curve map of beating among the embodiment 6 with the dependence of pulse dividing method, Figure 21 (b) is depicted as the curve map of beating among the embodiment 6 with the dependence of Writing power, and Figure 21 (c) is the curve map of the dependence of Rtop after rewriteeing for 10 times among the embodiment 6 and degree of modulation and Writing power.
Shown in Figure 22 for beat among the embodiment 6, Rtop and degree of modulation and the curve map of the dependence of number of rewrites repeatedly.
Curve map for beating among the embodiment 6 with the dependence of spot length shown in Figure 23.
Figure 24 (a) is depicted as the curve map of beating in the comparative example 2 with the dependence of pulse dividing method, Figure 24 (b) is depicted as the curve map of beating in the comparative example 2 with the dependence of Writing power, the curve map of the Rtop after Figure 24 (c) is depicted as and rewrites for 10 times and the dependence of degree of modulation and Writing power.
Figure 25 is expressed as the pulse dividing method of the used recording method of comparative example 3.
Curve map for beating in the comparative example 3 with the dependence of spot length and linear velocity shown in Figure 26.
Curve map for beating in the comparative example 6 with the dependence of Pw and Pe shown in Figure 27.
Curve map for beating among the embodiment 8 with the dependence of the shortest spot length shown in Figure 28.
The curve map of complying with for beating in embodiment 10 and the comparative example 8 with Pw shown in Figure 29.
Figure 30 is the key diagram of digital data signal and trochoidal wave form relation.
Figure 31 is for utilizing the principle key diagram of digital data signal modulated wobbles (wobblc) waveform.
Figure 32 is the curve map of the dependence of the groove width of degree of modulation and Rtop among the embodiment 11.
Embodiment
The present inventor finds, with crystalline state as not record and erase status, with the inversion of phases medium of amorphous state as recording status in, that utilizes that in fact the crystal growth that begins from amorphous portion or puddle and crystalline state portion boundary on every side carry out recrystallizes the medium of wiping and can carry out high speed and high density, stable record.That is to say, can carry out high speed and rewrite that it is little to carry out beating of spot border, highdensity spot length modulated record, the spot of formation has extraordinary long-time stability.
Usually, the erase process of amorphous state spot is that recording layer is heated to the temperature that is lower than fusing point more than the crystallized temperature slightly, forms the solid-state or molten condition of amorphous, recrystallizes when cooling then and finishes.
The present inventor studies show that, though it is to generate, 2. be that starting point is carried out these two processes of crystal growth and carried out with amorphous portion or puddle and crystalline state portion boundary by the nucleus in the 1. amorphous areas that the wiping of amorphous state spot promptly recrystallizes, but in fact the former nucleus generates hardly and takes place, and only utilize the latter's crystal growing process, can access above-mentioned effect.
Usually, crystallization is to carry out under the temperature that is lower than fusing point more than the Tc slightly, and it is that a side of lower temperature is carried out in this temperature range that nucleus generates, and crystal growth is to carry out at its high temperature side.Not talkative do not have the nucleus generation just can not wipe, if carry out crystal growth with the frontier point with crystalline state zone around amorphous portion or puddle at a high speed as nucleus, then can wipe.
Particularly small spot or short spot only utilize the crystal growth that crystalline state partly begins around such, are easy in the instantaneous time crystallization therefore can wipe fully in the extremely short time up to the spot center.Thereby having the high-density recording medium that the shortest spot length of employing is the following small spot of 0.5 μ m only, effect is just remarkable, can wipe below the 100 nanosecond orders of magnitude, can carry out the high speed rewriting.
And normally, the shortest spot length is short more can carry out high density recording more, but from the stability of spot, is preferably in more than the 10nm.
In addition, the transverse width of spot is narrow more, only utilizes from crystalline state on every side partly to begin crystal growth, and easy more instantaneous time crystallization is to the spot center, and this is desirable.Thereby this preferably the track pitch in the road of recorded information for example get below the 0.8 μ m, the spot transverse width is too not wide.Usually, the spot transverse width is about half of track pitch.Usually track pitch is narrow more, can carry out high density recording more, but from spot stability, be preferably in more than the 0.1 μ m.The road can only be a groove also, also can be groove and piston ring land.
Medium of the present invention also have the long-time stability of extraordinary amorphous state spot.
That is to say, the crystal growth that partly begins from crystalline state on every side, even more than Tc, be lower than slightly in the scope of fusing point, also only carry out in higher temperatures zone near fusing point, carry out hardly at low temperature, therefore in case form the amorphous state spot, just be difficult to crystallization, good long-time stability are arranged, Tc is usually in 100 ℃ ~ 200 ℃ scopes, before arriving about this temperature, can maintaining heat stability.
Particularly in less than 100 ℃ common usable range, the amorphous state spot of record is extremely stable, and the signal amplitude of noting is deterioration hardly.Otherwise also can draw and be accompanied by the conclusion that generates nucleus hardly from such long-time stability.
Moreover the advantage of medium of the present invention is, in the spot length records, can form few smooth spot border that rises and falls.
Usually when record amorphous state spot, be the temporary transient fusion of recording layer is solidified again and to form amorphous state, because the spot edge part is lower than central temperature, therefore, always cause crystallization again because of nucleus growth easily in the spot edge part, produce the coarse grain that amorphous state is sneaked into, this becomes the reason that the spot border rises and falls.
Medium of the present invention are characterised in that, when wiping, the crystal growth that begins from amorphous portion or puddle and crystalline state portion boundary is reigning, and carry out at a high speed, though also be that same principle works when writing down in this case, solidify again and when decrystallized at melt region, the crystal growth that partly begins from crystalline state on every side also only takes place, the crystallization that causes because of nucleus growth is not easy to take place, and the spot border is difficult for rising and falling.
That is to say, the crystal growth that partly begins from crystalline state on every side, even more than Tc, be lower than slightly in the scope of fusing point, also only carry out in higher temperatures zone near fusing point, carry out hardly at lower temperature, therefore when molten condition was solidified again, the cooling velocity when only descending by fusing point according to temperature decided the boundary shape of amorphous state spot.
Thereby what take place when the problem of Cun Zaiing is promptly solidified again in the past is mixed with amorphous coarse grain because of what nucleus growth produced, does not almost completely form around the amorphous state spot.Obviously this is extremely effective for the noise that suppresses to produce because of the fluctuating of spot border.
In addition, the spot boundary shape is also very stable, can time to time change, and beating when therefore not only beginning is little, and beats also hardly in time and deterioration.
Be described in more detail crystallization principle of the present invention below.
In these medium, the amorphous state spot partly is a crystal growth nuclear with crystalline state portion boundary on every side, produces nucleus hardly in amorphous state spot inside.Thereby, only begin crystal growth from the spot boundary member.
And existing GeTe-Sb 2Te 3Be recording layer, in the amorphous state spot, generate nucleus, this nucleus growth and then crystallization at random.
The difference of both crystallisation procedure does can be verified with transmission electron microscope.As if the light of wiping of two recording layer constant illumination lower-wattages after the amorphous state spot is formed, then can observe GeTe-Sb 2Te 3Be that recording layer begins crystallization from the high amorphous state spot middle body of temperature, and different therewith be, in recording layer of the present invention, can observe from amorphous state spot peripheral part and begin crystal growth.Particularly the crystal growth that begins from the front end and the rear end of amorphous state spot clearly.
The recording layer composition of wiping according to such principle mostly is at Sb 0.7Te 0.3Add the alloy system that superfluous Sb and other elements about maximum 20 atom % constitute in the contiguous composition of eutectic point.That is with M y(Sb XTe 1-X) 1-YAlloy is the film (0.6≤X in the formula≤0.9,0<y≤0.2, M is at least a among Ga, Zn, Ge, Sn, Si, Cu, Au, Al, Pd, Pt, Pb, Cr, Co, O, S, Se, Ta, Nb and the V) of principal ingredient.
Sb 0.7Te 0.3In contain the alloy of superfluous Sb, have following feature, promptly with GeTe-Sb 2Te 3Pseudobinary alloy system compares, and it is obviously big from the crystal growth that the crystal of amorphous state spot peripheral part begins, and therefore can rewrite with high linear speed.Superfluous Sb can not promote the nucleus at random in the amorphous state spot to generate and nucleus growth, but increases considerably the rate of crystalline growth that partly begins from crystalline state on every side.
But, in the SbTe bianry alloy, also generate a lot of nucleus, so the long-time stability extreme difference of amorphous state spot, suitable element must be added.
According to present inventor's research, adding Ge is to have effectively for suppressing the nucleus generation.
Moreover in fact whether the crystallization again of amorphous state spot only by the crystallization dominating role again that partly begins from crystalline state on every side, can be understood according to the evaluation of long-time stability indirectly.
As concrete evaluation method, method described below is arranged, measure the method for the degree of modulation of replay signal when promptly carrying out the acceleration environment test under hot and humid.
That is to say, when to utilize the shortest spot length be multiple spot length records signal below the 0.5 μ m, with M 0The degree of modulation of the signal of promptly resetting has just been noted in expression,
Record back is designated as M in the degree of modulation of the signal of resetting after through 1000 hours under 80 ℃ of 80%RH conditions 1, then satisfy following relation, promptly
M 1/M 0≥0.9
Spot length modulated mode is unqualified, can use EFM modulation, EFM enhancement mode modulation, (1,7) RLL-NRZI (run length limited-non return to zero inverted, promptly limited run-length code-IBM formula non-return-to-zero coding) modulation etc.With the shortest spot length be will be as shown in Figure 6 below the 0.5 μ m random signal record in addition, when carrying out this evaluation, preferably the shortest spot length be about 0.2 μ m more than.In addition, unnecessaryly all needn't satisfy following formula in the appreciation conditions, as long as in an appreciation condition, satisfy following formula.
For example utilize the random signal of the multiple spot length records EFM enhancement mode modulation system of the shortest spot length 0.4 μ m.
Degree of modulation is with maximum signal the signal amplitude of the longest spot of this modulation system to be carried out normalized value.DC replay signal (replay signal that contains DC component) waveform when Figure 6 shows that the random signal recording playback that EFM enhancement mode is modulated.Degree of modulation defines with the maximum signal Itop of 14T spot and the ratio I14/Itop of signal amplitude I14.
If degree of modulation is constant, can think that then the amorphous state spot size is highly stable.If the degree of modulation of the random signal of record is also keeping more than 90% of initial value before the accelerated test after the accelerated test, then can infer and in fact not follow the generation nucleus simultaneously.
In recording layer of the present invention, because the crystal growth that partly begins from crystalline state on every side takes place at the high-temperature area a little less than fusing point easily, therefore make the recording layer fusing in order to form the amorphous state spot, when solidifying again, also can partly begin to take place crystal growth from crystalline state on every side.Thereby cooling velocity is slow after fusion, fails to reach when solidifying needed critical cooling rate as amorphous state, and whole melt region is almost in moment crystallization again.
This can be confirmed by following experiment.
On the thick polycarbonate substrate of the 0.6mm of the groove that is provided with guiding recording playback light beam, set gradually (ZnS) of thickness 68nm 80 (SiO2) 20The 1st protective seam, the Ge of thickness 18nm 0.05Sb 0.71Te 0.24(ZnS) of recording layer, thickness 20nm 80(SiO 2) 20The 2nd protective seam and the Al of thickness 250nm 0.995Ta 0.005The reflection horizon, the ultraviolet hardening resin protective seam of thickness 4 μ m is set again.With two such substrates recording layer one side is arranged as the inboard, use up molten bonding agent and paste, constitute optical recording media.This recording layer consists of should be able to be with the Sb/Te ≈ 3 of the rewriting of the linear velocity more than about 7m/s.The elliptical laser of the about 100 μ m of major axis, the about 1.5 μ m of minor axis is scanned these medium at short-axis direction, make its fusion, crystallization again, realize initialization.
The focused beam of wavelength 637nm, NA=0.63 is radiated on these medium along the linear velocity of gathering sill with 7m/s.After recording power Pw is the recording light constant illumination of 10mW, sharply reduce power to 1mW.That is in fact cut off recording light.In addition, the about 0.9 μ m of beam diameter, the energy intensity that is equivalent in the Gaussian beam is the 1/e of peak strength 2Above zone.
Figure 2 shows that the reflectance varies of cutting off the recording light front and back.Shown in figure below of Fig. 2, cut off recording light through after a while.In the left side of Fig. 2 figure below, recording light is continuous, i.e. constant illumination, and recording light is cut off on the right side.With playback power is that the playback light of 1.0mW scans the same area, then obtains the playback waveform shown in the last figure of Fig. 2.This is corresponding to reflectance varies.
Near the instantaneous trip recording light, reflectivity descends, and before and after it, then reflectivity is basic identical, confirms according to tem observation, and the reflectivity sloping portion is an amorphous state, is crystalline state before and after it.That is to say, if the Continuous irradiation recording light, just crystallization again of puddle, and only near the melt region cut-out recording light part takes place decrystallized.
This is because during the Continuous irradiation recording light, utilize the waste heat of further part, the cooling velocity that has suppressed recording layer can not obtain forming the necessary critical cooling rate of amorphous state, otherwise and, in case the cut-out recording light is also just cut off the waste heat of further part, just can improve cooling velocity.
In addition, recording power Pw is made as 7mW when above, utilizes and cut off recording light, just can form the amorphous state spot.
By the result who studies as can be known, medium of the present invention are enough to make the recording light of the recording power Pw of recording layer fusion with certain linear velocity Continuous irradiation, then roughly recrystallize, be approximately 0 recording light with certain linear velocity irradiation power after the recording light of the recording power Pw that is enough to make the recording layer fusion again, promptly form the amorphous state spot.So-called power is approximately 0, and there is no need strictness is 0, is to get the bias power Pb that satisfies 0≤Pb≤0.2Pw, preferably the bias power Pb of 0≤Pb≤0.1Pw.
Recrystallizing when in the present invention, puddle solidifies again nearly all is only owing to the crystal growth that partly begins from solid phase crystalline state on every side causes.Thereby crystalline portion is not the core formation at the amorphous state spot again, so can form the spot border of smooth and continuous.
Thought always in the past that the obvious so easy material of crystallization again was not suitable for the recording layer that the spot length records is used.This be because, if form long spot and shine recording light for a long time, melt region crystallization nearly all then.
But, research according to the present inventor, in the high density recording below the shortest spot length is 0.5 μ m, the decrystallized of melt region and the competition process that recrystallizes that begins from the border of solid-phase crystallization polymorphic segment on every side actively are used, more can access good beating.
Therefore find, in the spot of length nT as described below forms, recording power Pw is applied interval and its cut-out interval, is that to apply the interval pulse partitioning scheme that is made up be extremely effective to bias power Pb.
If utilize the pulse partitioning scheme to carry out record, then as shown in Figure 1, form the amorphous state spot that fletching type (or selenodont) amorphous portion links to each other.
This spot front end shape is only by the shape decision of the front end of top fletching type amorphous portion, and this spot rear end shape is only by the shape decision of the rear end of rearmost fletching type amorphous portion.
Usually, because the front end shape of amorphous portion is smooth, so spot front end shape also is smooth.This is because forwards heat radiation, and cooling velocity keeps enough soon, thereby roughly reflects the shape of melt region front end, so decided by the recording impulse rising edge time.Recording impulse, be Pw apply interval rising edge so long as 2~3 nanoseconds following getting final product.
And the rear end shape of amorphous state part be by the cooling velocity of recording impulse negative edge time decision and from around, particularly the crystalline state size that partly begins the territory, recrystallization zone of carrying out in rear end decides.In order to make cooling velocity enough fast, Pw applies interval negative edge preferably below 2~3 nanoseconds.Territory, recrystallization zone size can utilize pulse cut off interval, be that Pb applies the length of an interval degree and correctly controls.
It is also of importance that, promptly adopt above-mentioned super chilling structure, the recording layer cooling velocity is sharply changed, near the spot rear end, make the space distribution of cooling velocity precipitous simultaneously, so that the spot end position does not does not rise and fall as layer structure.
The present inventor is according to found that of the wholwe-hearted research of optical recording media of the long-time stability excellence of can high-speed record short spot and record spot, at Sb 0.7Te 0.3Near the specific composition that adds Ge the eutectic composition is excellent especially, simultaneously by suitably selecting layer structure, has obtained the also excellent optical recording media of other characteristics.
That is to say, note having studied Sb 0.7Te 0.3The ternary alloy three-partalloy that did not in the past have that adds superfluous Sb and Ge and obtain has been discussed the adaptability to high density spot length modulated record.Found that, in GeSbTe ternary state diagram shown in Figure 3, if adopting the recording layer of the extremely limited Ge-Sb-Te ratio of 4 straight line A, B, C, D encirclement forms, in high density spot length modulated record, it rewrites permanance repeatedly and long-time stability are excellent especially with these medium that constitute.
That is to say, will be in the GeSbTe ternary state diagram,
Has usefulness
Connect (Sb 0.7Te 0.3) with the straight line A of Ge,
Connect (Ge 0.03Sb 0.68Te 0.29) and (Sb 0.95Ge 0.05) straight line B,
Connect (Sb 0.9Ge 0.1) and (Te 0.9Ge 0.1) straight line C and
Connect (Sb 0.8Te 0.2) with the straight line D of Ge
Deng the GeSbTe alloy of the composition of 4 straight line area surrounded (but not comprising on the boundary line) is that the film of principal ingredient is as recording layer.By adopting layer structure described later, formation is very suitable for the medium that the shortest spot length is the following high density spot length modulated record of 0.5 μ m to this recording layer.And, can access the recording density identical with DVD and and DVD between the playback interchangeability of excellence.
And, can also guarantee to obtain the less required enough surpluses of beating for the change that rewrites permanance and recording power and erase power repeatedly.
In this compositing range, at Sb yTe 1-yIn the alloy, the amount than y=0.7 is many for the Sb amount, and then superfluous Sb amount increases, and crystallization rate is fast more, can realize the rewriting of high linear speed.
More particularly, in EFM enhancement mode modulation record (the spot length modulated records of 8-16 modulation), even 3T spot contraction in length to the 0.4 μ m or the 0.35 μ m of short spot also can access less beating.Can access enough servosignals again, can in existing read-only DVD driver, carry out tracking servo.Can also on-line velocity be to rewrite under any linear velocity of 1~10m/s.
By means of this, can access the erasable DVD that has playback interchangeability with read-only DVD same capability, basically.
If the Sb amount that control is superfluous can also realize the highdensity rewriting of above-mentioned high-quality with the high linear speed more than the 8m/s.In addition, as described below according to linear velocity change recording impulse dividing method (pulse strategy), can in comprising the very wide linear velocity scope of 3~8m/s at least, realize good rewriting.
Describe this composition below in detail.
At the Ge addition is Sb below the 10 atom % 0.7Te 0.3In the contiguous composition of eutectic point, Sb/Te is bigger than more, and crystallization rate has the trend of accelerating.This is because and Sb 0.7Te 0.3Compare is that superfluous Sb is separating out as the Sb atomic group and working as nucleus in recrystallization process.And and Sb 0.7Te 0.3Compare when not having superfluous Sb, wipe poor performance, in fact can not rewrite.In addition, almost do not have karyogenesis during owing to initialization, therefore also have the problem (straight line A) of initialization difficulty, the non-constant of production efficiency.
On the other hand, if at Sb 0.7Te 0.3Increase the Sb amount in the eutectic bianry alloy, then crystallization rate is accelerated, otherwise and Tc also descends, damaged the long-time stability of amorphous state spot.Again, be not suitable for the record of the low linear velocity about 3m/s, the amorphous state spot of formation promptly is wiped free of with playback light (about the about 1mW of the laser power) irradiation of short time.Thereby, should not comprise than connecting (Sb 0.8Te 0.2) with the superfluous Sb of straight line D of Ge.
Again, in the scope that the superfluous Sb with straight line A and D regulation measures, when keeping the SbTe binary constant, because Tc is low, and exists the nucleus of superfluous Sb, cause the amorphous state spot too unstable, therefore superfluous Sb measures many more, adds Ge more.Utilize 4 coordination bonds of Ge, almost completely suppress nucleus and generate.Tc rises as a result, and long-time stability increase.Connect (Ge 0.03Sb 0.68Te 0.29) and (Sb 0.95Ge 0.05) straight line B stipulated this condition.Better is than connecting (Ge 0.03Sb 0.68Te 0.29) and (Sb 0.9Ge 0.1) straight line B ' contain more Ge.
Have, if Ge content reaches more than the 10 atom %, the deterioration of beating during spot degree length records then is owing to rewrite the easy segregation of dystectic Ge compound, particularly GeTe repeatedly again.In addition because just the amorphous film crystallization after the film forming is extremely difficult, this be unfavorable (straight line C).Beat in order to reduce, preferably getting Ge is below the 7.5 atom %.
In addition, for to rewrite more than the linear velocity 3m/s, recording layer preferably adopts Ge x(Sb yTe 1-y) 1-xAlloy is the film (0.04≤x<0.10,0.72≤y<0.8) of principal ingredient.That is to say,, preferably increase the Sb amount, at Sb for the record more than the linear velocity 3m/s yTe 1-yIn the alloy, preferably make y 〉=0.72.Here,, cause amorphous state spot stability that some deteriorations are arranged,, preferably make Ge some more, reach x 〉=0.04 in order to remedy this point owing to increase the Sb amount.
Moreover for the rewriting more than the linear velocity 7m/s, recording layer preferably adopts Ge x(Sb yTe 1-y) 1-xAlloy is the film (0.045≤x≤0.075,0.74≤y<0.8) of principal ingredient.That is to say that for the record more than the speed 7m/s, preferably again Sb amounts that increase at Sb more yTe 1-yIn the alloy, preferably make y 〉=0.74.At this moment, in order to improve the stability of amorphous state spot, make the Ge amount satisfy x 〉=0.045.On the other hand, the easy deterioration of beating under high linear speed in order to remedy this point, makes the Ge amount satisfy x≤0.075.
So far formed relevant for the GeSbTe ternary or with this tlv triple become parent contain the report that the recording layer that adds element forms deliver (the Jap.P. spy open clear 61-No. 258787 communiques, spy open clear 62-No. 53886 communiques, spy open clear 62-No. 152786 communiques, spy open flat 1-No. 63195 communiques, spies open flat 1-No. 211249 communiques, spies open put down 1-No. 277338 communiques).
But the described composition of these communiques all is that Sb is less than connection (Sb 0.7Te 0.3) with the composition of the straight line A of Ge, with compositing range of the present invention little with.
These also are with Sb certainly 2Te 3Metallic compound consists of main body.In addition, at GeTe-Sb 2Te 3In the pseudobinary alloy system, opposite with the present invention, because superfluous Sb has the effect of the crystallization rate that slows down, therefore when rewriteeing, at GeTe-Sb with the above high linear speed of 5m/s 2Te 3On the straight line, particularly make Ge 2Sb 2Te 5Form and to contain superfluous Sb, it is harmful that yes.
Containing the Sb of superfluous Sb 0.7Te 0.3Near add the composition of the 3rd element comprise Ge selectively, the compositing range α of 1-No. 100745 communiques of Japanese patent laid-open (Fig. 4 (a)) is arranged) and the spy open the composition described in flat 1-No. 303643 communiques (the compositing range β of Fig. 4 (a)).
But it is to form Sb at parent that the spy opens flat 1-No. 100745 communiques 1-xTe xIn, there is extremely wide scope 0.10≤x≤0.80, and does not have the application's thought, promptly compares Sb by only utilizing 0.7Te 0.3There are excellent rewriting permanance repeatedly and long-time stability in the zone that superfluous Sb is arranged in high density recording.
1-No. 303643 communiques of Te Kaiping do not touch in the high density recording as the application if contain superfluous Sb above straight line D, will damage the drawback of amorphous state spot long-time stability.In addition, these communiques all do not touch yet and contain the drawback that the superfluous Ge above straight line C causes.
Again, as forming by forming that part repeats with recording layer of the present invention, as described in Fig. 4 (b), have that 1-No. 115685 communiques of Japanese patent laid-open (compositing range γ), spy open flat 1-251342 communiques (compositing range δ), the spy opens flat 3-No. 71887 communiques (compositing range ε) and the spy opens flat 4-No. 28587 (compositing range η) described compositions.
1-No. 115685 communiques of Te Kaiping are to be that parent adds Au and Pd forms with compositing range γ, are recorded as purpose with low-density, utilize straight line A and straight line B and composition of the present invention, can be from being distinguished in essence.It is that low-density record (square wave of linear velocity 4m/s, frequency 1.75MHz, dutycycle 50%) and the DC of about 1.1 μ m wipes that the disclosed composition of this communique is suitable for being equivalent to spot length, therefore can think, be that to form pairing composition be different for the present invention of purpose with the high density recording with what contain short spot.
The compositing range δ of 1-No. 251342 communiques of Te Kaiping is to Sb 0.7Te 0.3The alloy that eutectic adds the above Ge of about 10 atom % is the GeSbTe system that is rich in Ge of main body, forms with the present invention and can utilize straight line C from being distinguished in essence.Contain in compositing range δ in the composition more than 10 atom %Ge, its fatal problem is that crystallization rate is slow as previously mentioned, particularly make the initialization operation difficulty of the recording layer crystallization after the film forming, so production efficiency is low, can not be for practical.In this communique, in order to overcome the problem of this crystallization rate, add Au and Pd in addition, but be less than in the zone of straight line C at Ge as the present invention as nucleus, but there is not this necessity.
Again, in this communique, also record,, then can not obtain enough light quantity variations at recording section and non-recording section if the Ge amount is less than 10 atom %.And in the present invention, by the layer structure that contains matcoveredn and reflection horizon taken measures, can access the very large reflection light quantity of degree of modulation more than 60% and change.
The compositing range ε of 3-No. 71887 communiques of Te Kaiping is recorded as purpose with low-density, forms with the present invention and can utilize straight line C to be distinguished in itself.Particularly do not utilize compositing range of the present invention, in high density recording, obtain the excellent thought that rewrites permanance and this application of long-time stability repeatedly.
The compositing range η of 4-No. 28587 communiques of Te Kaiping comprises high Sb and the composition of Ge, forms with the present invention and can utilize straight line D to be distinguished in itself.
As mentioned above, the shortest spot length that above-mentioned all communiques are not all illustrated as the object of the invention is the relevant technical matters of high density spot length modulated record such below the 0.5 μ m, does not have to disclose used for this reason the best fully and forms improving one's methods of selection and layer structure and recording method.
The following describes the layer structure of optic informating recording medium of the present invention.Medium of the present invention are made up by recording layer and the following layer structure with above-mentioned composition, can be implemented in and carry out the shortest spot length when being the following high density spot length modulated record of 0.5 μ m, be at least 3m/s to 8m/s, better be the medium that the very wide linear velocity scope of 1m/s to 10m/s rewrites.Thereby, can keep with the playback of so-called DVD and exchange.
Phase change type recording layer is covering with protective seam up and down at least on one side.
And for example shown in Fig. 5 (a), have the formation in substrate 1/ the 1st protective seam 2/ recording layer 3/ the 2nd protective seam 4/ reflection horizon 5, cover (protection overlayer 6) with ultraviolet ray or thermosetting resin thereon again.Each layer order shown in Fig. 5 (a) is adapted to pass through focused beam that transparency carrier uses recording playback and is radiated at situation on the recording layer.
Or with the reversed in order of above-mentioned each layer, the structure that also can adopt the sequential cascade of substrate 1/ reflection horizon 5/ the 2nd protective seam 4/ recording layer 3/ the 1st protective seam 2 shown in Fig. 5 (b) to form.This layer structure is suitable for from the situation of the 1st protective seam one side incident focused beam.Such formation is useful for the situation that numerical aperture of objective NA is, recording layer and object lens distance are sought after shortening more than 0.7.
If adopt the structure shown in Fig. 5 (a), then substrate can adopt transparent resin or clear glasses such as polycarbonate, acrylic glass, polyolefin.
Wherein, polycarbonate resin has had in CD uses actual achievement the most widely, and price is cheap again, therefore ideal.
In the formation shown in Fig. 5 (b), though can use resin or glass too, substrate itself there is no need transparent, in order to improve flatness and rigidity, preferably adopts glass or aluminium alloy sometimes certainly.
In the spacing that guiding recording playback light is set on the substrate is groove below the 0.8 μ m, and this groove not necessarily must be geometric dovetail groove, for example also can utilize ion to inject and form the different such optics groove of waveguide of refractive index.
In the layer structure shown in Fig. 5 (a), in order to prevent to cause distortion, the 1st protective seam 2 is set on substrate surface because of the high temperature in when record, the 2nd protective seam 4 is set on recording layer 3.The 2nd protective seam 4 has the counterdiffusion mutually that prevents between recording layer 3 and the reflection horizon 5 concurrently, suppresses the function of recording layer distortion and efficiently to the function of reflection horizon 5 heat radiations.
In Fig. 5 (b), from the focused beam light incident side, the 2nd protective seam 4 has the counterdiffusion mutually that prevents between recording layer 3 and the reflection horizon 5, dispels the heat and prevents the function of recording layer distortion.The 1st protective seam among Fig. 5 (b) has and prevents recording layer distortion, prevents that recording layer from directly contacting (preventing oxidation stain etc.) and prevent from directly to contact with laser head and the function that sustains damage with air.
Between reflection horizon and substrate, also protective seam can be set again.For example can prevent fire damage to resin system substrate.
In the structure shown in Fig. 5 (b), the arranged outside again that is preferably in the 1st protective seam 2 is than its harder dielectric or amorphous carbon diaphragm, or ultraviolet ray or thermosetting resin layer are set.Perhaps also can paste the transparent thin board about thickness 0.05~0.6mm, by this thin plate incident focused beam.
Have, in the such medium of DVD, employing is made structure inboard, that the medium of Fig. 5 (a) are pasted mutually with bonding agent with the record aspect again.For the medium of Fig. 5 (b), then conversely the record aspect is pasted mutually as the outside.In the medium of Fig. 5 (b), can also utilize injection molding to form the groove of following the tracks of usefulness on the two sides of a plate base, utilize formation multilayer films such as sputtering method on the two sides.
Recording layer 3, protective seam 2,4, reflection horizon 5 utilize method formation such as sputtering method.
Preferably adopt recording layer with target, protective layer used target, also have reflector material to carry out the formation work of film in case of necessity, can prevent the oxidation and the pollution of each interlayer like this with the on-line unit that target is arranged in the same vacuum chamber.
The decision of protective seam 2 and 4 material will notice that refractive index, pyroconductivity, chemical stability, physical strength and stickability etc. decide.Usually can adopt the fluoride of good, the high-melting point metal of the transparency or semi-conductive oxide, sulfide, nitride, carbonide or Ca, Mg, Li etc.
These oxides, sulfide, nitride, carbonide, fluoride not necessarily must be got the composition of its stoichiometric proportion, in order to control refractive index etc., perhaps control its composition, perhaps mix and use, and these methods also all are effective.
Protective seam 2 and 4 also can change its ratio of components or mixing ratio at thickness direction.Again, protective seam 2 and 4 also can be made of several tunics respectively.Each tunic can be according to desired characteristic, gets different materials, different ratio of components or mixing ratio.
If consider that recording characteristic repeatedly, the film density of these protective seams are more than 80% of loose dress state, this considers from the physical strength aspect is desirable.With the potpourri thin dielectric film time, bulk density adopts the solid density of following formula.
P=∑m iP i (1)
M i: the molarity of each component i
P i: independent bulk density
The recording layer 3 of medium of the present invention is a phase change type recording layer, and its thickness is general preferably in the scope of 5nm~100nm.
If the thickness of recording layer 3 is thinner than 5nm, then be difficult to obtain enough contrasts, and the slack-off trend of crystallization rate is arranged, cause the situation that is difficult to wipe at short notice easily.
On the other hand,, be difficult to obtain the optics contrast equally, be easy to generate crackle again if surpass 100nm.
Also have, for the contrast that must have with the degree of the interchangeability of read-only disc such as DVD, and the shortest spot length is the following such high density recording of 0.5 μ m, is preferably in below the above 25nm of 5nm.When 5nm is following, because reflectivity is low excessively, and occur easily that the composition of film early growth period is inhomogeneous, the influence of sparse film, therefore undesirable.
And if thicker than 25nm, then thermal capacity is big, and recording sensitivity is poor, and crystal growth simultaneously is three-dimensional, the border disorder of amorphous state spot is arranged, the serious trend of beating.Moreover the volume change that is caused by the recording layer phase transformation is remarkable, rewrites poor durability repeatedly, and is therefore also undesirable.It seems from the viewpoint of beating and rewriteeing permanance repeatedly of spot end, be preferably in below the 20nm.
Again, the density of recording layer is more than 80% of bulk density preferably, and better is more than 90%.Here so-called bulk density can certainly be made alloy block and survey, but in above-mentioned (1) formula, and the molarity of each composition is replaced as each atoms of elements %, and bulk density is replaced as each element molecular weight, also can obtain approximate value with this.
The density of recording layer is in the spatter film forming method, and the sputter gas in the time of must taking to reduce film forming rare gas such as () Ar pressure near methods such as target front placement substrates, and increases the high-energy Ar amount of irradiation recording layer.High-energy Ar is that the Ar ion part rebound of the irradiation target used of sputter arrives the ion of substrate-side or the Ar ion in the plasma because the ion sheath voltage of whole of substrate quickens to arrive the ion of substrate.
The illumination effect of such high energy rare gas is called atomic peening (atom injection) effect.In the sputter of the general Ar gas that uses, because atomic peening effect is sneaked in the sputtered film Ar.According to the amount of the Ar in the film, can estimate atomic peening effect.That is to say,, mean that then the illumination effect of high energy Ar is little, form the sparse film of density easily if the Ar amount is few.On the other hand, if the Ar amount is many, then the irradiation of high energy Ar is strong, though density is high, the Ar that enters in the film separates out as void (space) when rewriteeing repeatedly, makes and rewrites the permanance variation repeatedly.Proper A r amount is below the above 1.5 atom % of 0.1 atom % in the record tunic.Moreover, adopt high-frequency sputtering to compare with d.c. sputtering, the Ar amount is few in the film, can obtain density film, and is therefore more satisfactory.
In the present invention, recording layer is made of the film that to have the above-mentioned GeSbTe alloy that constitutes be major component.That is to say that the ratio of the Ge in the recording layer, Sb, each amount of element of Te is as long as in above-mentioned compositing range, recording layer also can add other element that amounts at most about 10 atom % as required.
Again by adding more than at least a kind of element 1 atom % that selects among O, N, the S below the 5 atom %, just can finely tune in the recording layer the optical constant of recording layer.But, if addition surpasses 5 atom %, crystallization rate is reduced, wipe degradation, be unfavorable therefore.
Again, the crystallization rate when rewriteeing in order not reduce increases long-time stability, preferably adds at least a among 8 atom % following V, Nb, Ta, Cr, Co, Pt and the Zr.Better is to add below the above 5 atom % of 0.1 atom %.These total addition levels that add element and Ge are preferably in below the 15 atom % with respect to SbTe.If the content surplus, then cause being separated beyond the Sb.Particularly Ge content is when 5 atom % are following more than 3 atom %. and additive effect is big.
In order to improve long-time stability and refractive index is finely tuned, preferably add at least a among 5 atom % following Si, Sn and the Pb.These total contents that add element and Ge are preferably in below the 15 atom %.These elements are identical with Ge, have 4 coordinated networks.
Add 8 atom % following Al, Ga and In, Tc will be risen, reduce simultaneously and beat, also produce effect to improving recording sensitivity, but also be easy to generate segregation, therefore be preferably below the 6 atom %.Wish below 15 atom %, to be preferably below 13% with the content of Ge total again.
If add the Ag of 8 atom %, producing effect equally aspect the raising recording sensitivity, particularly when surpassing 5 atom %, adopts the Ge atomic weight, more remarkable effect, still, add above 8 atom % and can make the increase of beating, or the stability of damage amorphous state spot, be unfavorable therefore, if surpass 15 atom % with the total addition of Ge, then being easy to generate segregation, is unfavorable therefore.The content of Ag is preferably in below the 5 atom %.
The recording layer 3 of recording medium of the present invention, the state after the film forming is an amorphous state usually.Thereby, make whole crystallization of recording layer as init state (not recording status) after the film forming.
As initial method, for Sb 0.7Te 0.3In contain the alloy of superfluous Sb, though utilize the annealing under the solid phase also can carry out initialization, under the situation of the composition that also contains Ge, preferably adopt to make the temporary fusion of recording layer and make it slowly cool off the initial methods of the melting recrystallization of crystallization again when solidifying again.
This recording layer does not almost have the nuclear of crystal growth after firm film forming, the crystallization under solid phase is difficult to, but adopts melting recrystallization method method, then forms the minority nucleus, and fusion then is main crystallization more at full speed with the crystal growth.
In addition, the reflectivity of the crystal that produces of annealing under the crystal that recording layer of the present invention is produced by melting recrystallization and the solid phase is different, mixes as if both, then becomes the root of noise.And when carrying out regenerative recording, wiping part becomes the crystal that melting recrystallization produces actual, and therefore preferably initialization also utilizes melting recrystallization to carry out.
At this moment, making the recording layer fusion is locality, and is limited to the short time following about 1 millisecond.This is because if melt region is big, or melting time or cool time are long, then are damaged because of heating can make each layer, perhaps make the plastic base surface deformation.
In order to provide such thermal history, preferably become the light beam of major axis 100~300 μ m, minor axis 1~3 μ m to shine the high output semiconductor laser focusing about wavelength 600~1000nm, short-axis direction as scan axis, is scanned with the linear velocity of 1~10m/s.Even use identical focused beam, if near circular, then melt region is excessive, and is decrystallized once again easily, can cause than macrolesion sandwich construction or substrate again, and be unfavorable therefore.
Initialization is carried out this point by melting recrystallization, can obtain confirming by following way.That is to say, shine medium after this initialization less than recording light about 1.5 μ m, that have the recording power Pw that is enough to make the recording layer fusion with certain linear velocity constant being focused into spot diameter.When gathering sill was arranged, the road that constitutes between to this groove or groove carried out carrying out under the state of tracking servo and focus servo.
Then, go up constant illumination to phase people having a common goal and have erase power Pe (≤wiping light and obtain erase status Pw), if the reflectivity of the reflectivity of described erase status and complete Unrecorded original state much at one, can confirm that then this init state is the melting recrystallization state.
This is because utilize the recording light irradiation to make the temporary fusion of recording layer, and then with wiping this state that rayed makes its perfect recrystallization, be through utilizing the fusion of recording light and the recrystallization process that light is wiped in utilization, being in the state of melting recrystallization.
The reflectivity Rini of so-called init state and the reflectivity Rcry of melting recrystallization state much at one, be meant by (Rini-Rcry)/(Rini+Rcry)/both reflection differences that 2} defines are below 20%.Usually, only by solid phase crystallizations such as annealing, its reflection differences is greater than 20%.
Narrate relevant recording layer other layers in addition below.
Layer structure of the present invention belongs to a kind of layer structure that is called the chilling structure.The chilling structure is the layer structure of the cooling velocity when promoting that by employing dispelling the heat, improve recording layer solidifies again, and the problem that recrystallizes when avoiding the amorphous state spot to form utilizes high speed crystallization realization height to wipe ratio simultaneously.For this reason, the 2nd protective seam thickness is got below the above 30nm of 5nm.If thinner than 5nm, then because the distortion during the recording layer fusion etc. cause damage easily, and radiating effect is excessive, and it is excessive and there is no need then to write down desired power.
The 2nd protective seam thickness of the present invention has a significant impact the permanance that rewrites repeatedly, and is also very important on deterioration is beated in inhibition especially.Under the thick situation of Film Thickness Ratio 30nm, the temperature difference in record one side of the 2nd protective seam and reflection horizon one side during record is big, because the thermal expansion of protective seam both sides is poor, itself is easy to generate assymmetrical deformation protective seam.This situation takes place repeatedly, will cause noise to increase in the plastic yield of the inner savings of protective seam microcosmic, is unfavorable therefore.
If adopt recording layer of the present invention, then in the high density recording below the shortest spot length is 0.5 μ m, though can realize low beating, but research according to the present inventor, when adopting short wavelength laser diode (for example below the wavelength 700nm) in order to realize high density recording, to note for the layer structure of above-mentioned chilling structure is more essential.Adopt particularly that wavelength 500nm is following, numerical aperture NA is less focused beam research single beam 0.55 or more when rewriteeing characteristic, recognizes that smooth to wipe when big erase power surplus be very important for obtaining height for the Temperature Distribution of the Width that makes spot.
This trend is that the optical system corresponding with DVD of the optical system about 630~680nm, NA=0.6 also is same for adopting wavelength.In adopting the high density spot length modulated record of such optical system, adopt the low material of pyroconductivity especially as the 2nd protective seam.Preferably making its thickness is below the above 25nm of 10nm.
Under any circumstance, the material that special high thermoconductivity is adopted in the reflection horizon 5 that is provided with thereon can improve like this and wipe erase power surplus when.
According to research, in very wide erase power scope, in order to bring into play the good erasing characteristic that recording layer of the present invention has, preferably adopt the smooth as far as possible layer structure of Temperature Distribution that the Temperature Distribution can not only make film thickness direction and time changes but also make face direction (vertical direction of writing light beam direction of scanning).
The present inventor attempts the layer structure by suitable design media, makes the transverse temperature distribution in road in the medium smooth, no longer decrystallized after the fusion like this, and strengthens the width of crystallization again, increases erasure rate and erase power surplus.
On the other hand, also recognize the 2nd protective seam low by pyroconductivity and as thin as a wafer, promote to dispel the heat to the reflection horizon of high pyroconductivity, make the Temperature Distribution in the recording layer become smooth like this from recording layer.Can promote radiating effect though improve the pyroconductivity of the 2nd protective seam, if excessively promote heat radiation, then write down needed irradiation power height, promptly recording sensitivity significantly descends.
In the present invention, preferably adopt low-thermal conductivity and the 2nd thin protective seam.
Owing to adopt the 2nd thin again protective seam of low-thermal conductivity; therefore among the several nsec~number+nsec when beginning to shine with recording power; can have the certain hour delay from the heat conduction of recording layer to the reflection horizon; can promote heat radiation then, so can excessively not reduce because of heat radiation makes recording sensitivity to the reflection horizon.
In the past with SiO 2, Ta 2O 5, Al 2O 3, AlN and SiN etc. are the protective layer material of principal ingredient, because the pyroconductivity of itself is too high, therefore are not suitable as the 2nd protective seam 4 of medium of the present invention.Like this, the pyroconductivity of metal oxide or nitride, even compare with same filminess, also used than the present invention protective seam following protective seam of its pyroconductivity is high 1 more than the order of magnitude.
On the other hand, the heat radiation in reflection horizon also can be carried out even the thickness in reflection horizon is thicker, but if reflector thickness surpasses 300nm, then the heat conduction of film thickness direction than recording layer face direction significantly, the effect of the face direction Temperature Distribution that can not improve.Again, the thermal capacitance quantitative change in reflection horizon itself is big, and the cooling of reflection horizon and then recording layer just needs the time, has just hindered the formation of amorphous state spot.The thin reflection horizon of high thermoconductivity preferably is set, promotes selectively to horizontal heat radiation.
The chilling structure that in the past adopted is only noted the one dimension heat radiation of film thickness direction, only plans to dispel the heat to the reflection horizon soon from recording layer, and sufficient attention is given in the planarization of this in-plane Temperature Distribution.
If what is called of the present invention " is considered the super chilling structure of the heat conduction late effect of the 2nd protective seam " and is used for recording layer of the present invention, then with in the past GeTe-Sb 2Te 3Recording layer has been compared better effect.This is because near the crystal growth when recording layer of the present invention solidifies Tm again becomes the reaction rate of crystallization again.For near the cooling velocity the Tm is increased to the limit, reliably and clearly form amorphous state spot and border thereof, super chilling structure is effective, and by making face direction Temperature Distribution smooth, originally near Tm, can wipe at a high speed, can both guarantee to utilize crystallization secure erasure again up to the degree of higher erase power.
In the present invention, as the low material of the preferably hot biography rate of material of the 2nd protective seam, its roughly numerical value be 1 * 10 -3PJ/ (μ mKnsec).But, being difficult to the pyroconductivity of the such low thermal conductivity material filminess of directly measurement, the replacement way can be that the measurement result according to thermal simulation and physical record sensitivity obtains roughly numerical value.
As the 2nd protective layer material of low-thermal conductivity, preferably contain the above 90mol% of 50mol% following ZnS, ZnO, TaS with desired result 2Or it is at least a and contain fusing point or decomposition point is the composite dielectrics of the heat-resisting compound more than 1000 ℃ in the terres rares sulfide.
More particularly, the composite dielectrics that preferably contains the rare-earth sulfide of the above 90mol% of 60mol% following La, Ce, Nd, Y etc.
Perhaps preferably make ZnS, ZnO or rare-earth sulfide compositing range at 70~90mol%.
Fusing point or decomposition point are the heat-resisting compound-material more than 1000 ℃ as mixing with these, can adopt the fluoride of oxide, nitride, carbonide or Ca, Mg and the Li etc. of Mg, Ca, Sr, Y, La, Ce, Ho, Er, Yb, Ti, Zr, Hf, V, Nb, Ta, Zn, Al, Si, Ge and Pb etc.
The particularly material that will mix, preferably sulfide or the sulfide and the hopcalite of rare earths such as Y, La, Ce and Nd with ZnO.
And, if the 2nd protective seam thickness greater than 30nm, then can not obtain the enough smooth effect of spot width direction Temperature Distribution, therefore adopt below the 30nm, be preferably below the 25nm.If less than 5nm, then insufficient at the heat conduction carryover effects of the 2nd protective seam part, recording sensitivity significantly descends, and is unfavorable.
The thickness of the 2nd protective seam 4 is preferably 15nm~25nm when the recording laser wavelength is 600~700nm, when wavelength is 350~600nm, be preferably 5~20nm, and better is 5~15nm.
Be characterised in that in the present invention, adopt thin reflection horizon 5 very high pyroconductivity, that 300nm is following to promote the heatsink transverse effect.
Usually, the pyroconductivity of the pyroconductivity of film and loose dress state has a great difference, and general case is to diminish.Particularly less than the film of 40nm, under the influence of early growth period island structure, it is little 1 more than the order of magnitude that pyroconductivity is wanted, and this situation is unfavorable.Moreover because of the membrance casting condition difference, crystallinity and impurity level are also different, even this is same composition and the also different main cause of pyroconductivity.
In the present invention, the reflection horizon for the high thermoconductivity of determining to demonstrate superperformance though also can directly measure the pyroconductivity in reflection horizon, utilizes resistance also can estimate its heat conducting quality.This is because in the main material of being undertaken heat conduction and conductivity by electronics as metal film, pyroconductivity and conductivity have good proportionate relationship.
The resistance of film is represented with the numerical value of the resistivity of the area normalization of its thickness or measured zone.Specific insulation and area resistivity can be measured with common four probe method, are defined as foundation with JIS K7194.Utilize this method, compare with the pyroconductivity of actual measurement film itself and want much easy, and can obtain the data of good reproducibility.
In the present invention, the specific insulation in desirable reflection horizon is below the above 150n Ω of the 20n Ω m m, is preferably below the above 100n Ω of the 20n Ω m m.In fact specific insulation is difficult to obtain in filminess less than the material of 20n Ω m.Specific insulation compares under the big situation of 150n Ω m, if if adopt the thick film that for example surpasses 300nm, though then can reduce area resistivity, but as can be known according to present inventor's research, with so high volume resistivity material, only reduce area resistivity, can not obtain enough radiating effects.Can think that this is owing under the thick film situation, the cause that the thermal capacity of unit area increases.In addition, such thick film film formation time is long, and fee of material also increases, and sees it also is unfavorable from the viewpoint of manufacturing cost.Moreover the microcosmic flatness on film surface is also poor.
Preferably adopting thickness is that 300nm is following, to obtain area resistivity be low volume resistivity material below 0.9 Ω 0.2 or more/.That better is 0.5 Ω/.
It is as follows to be suitable for material of the present invention.
The Al-Mg-Si that for example contains the following Mg of following Si of the above 0.8 weight % of 0.3 weight % and the above 1.2 weight % of 0.3 weight % is an alloy.
Again, the Al alloy that contains following Ta, Ti, Co, Cr, Si, Sc, Hf, Pd, Pt, Mg, Zr, Mo or Mn of the above 2 atom % of 0.2 atom % among the Al, the increase that is directly proportional with the concentration of adding element of its specific insulation, can improve anti-(hillock) performance of separating out unusually again, from considerations such as permanance, specific insulation and film forming speeds, can adopt.
About the Al alloy, be less than under the situation of 0.2 atom % adding impurity, though also depend on membrance casting condition, often anti-to separate out performance unusually insufficient.And if, then be difficult to obtain above-mentioned low-resistivity more than 2 atom %.
For the situation of special attention long-time stability, the most handy Ta of adding ingredient.Particularly for the upper protective layer 4 that is principal ingredient, as the reflection horizon that can take into account complete characteristics such as corrosion stability, stickability and high thermoconductivity, be desirable material with ZnS with the AlTa alloy of the following Ta of the above 0.8 atom % of 0.5 atom %.Again, add the situation of the Ta of 0.5 atom % a little, with pure Al or Al-Mg-Si alloy phase ratio, the rate of film build during sputter has improved 30%~40%, can obtain desirable effect on making.
When adopting above-mentioned Al alloy as the reflection horizon, desirable thickness is below the above 300nm of 150nm.Less than 150nm the time, promptly use pure Al, radiating effect is also insufficient.And if surpass 300nm, then heat dispels the heat to vertical direction from horizontal direction, and for the not improvement effect of heat distribution of horizontal direction, and the thermal capacity in reflection horizon itself is big, and the cooling velocity of recorded instead layer is slack-off.And the microcosmic flatness on film surface is also poor.
Moreover the Ag alloy that contains the following Ti of 5 atom %, V, Ta, Nb, W, Co, Cr, Si, Ge, Sn, Sc, Hf, Pd, Rh, Au, Pt, Mg, Zr, Mo or Mn more than the 0.2 atom % in Ag also is a desirable material.Under the situation of special attention long-time stability, Ti, Mg are desirable as adding ingredient.
When adopting the reflection horizon of above-mentioned Ag alloy conduct, desirable thickness is below the above 150nm of 40nm.Less than 40nm the time, promptly use the fine silver radiating effect also insufficient.And if surpass 150nm, then heat distributes to vertical direction from horizontal direction, and for the not effect of improvement of horizontal direction heat distribution, and unnecessary thickness reduces production efficiency.In addition, also variation of the microcosmic flatness on film surface.
The present inventor confirms, for interpolation element among the above-mentioned Al and the interpolation element among the Ag, and the specific insulation increase that is directly proportional with concentration of these interpolation elements.
It is believed that adding impurity makes brilliant thick diameter reduce usually, the electron scattering of crystal boundary is increased, pyroconductivity reduces.For by increasing crystal grain diameter, must regulate the impurity addition to obtain the original high thermoconductivity of material.
Also have, the reflection horizon forms with sputtering method or vacuum vapour deposition usually, though the impurity level of target and deposition material itself also disappears, must make the moisture and the amount of oxygen of sneaking into when comprising film forming is below the 2 atom % at interior all dirt content.Therefore, wish to handle vacuum chamber and be less than 1 * 10 -3The vacuum tightness of Pa.
Again, if in vacuum tightness than 10 -4Film forming under the situation of Pa difference wishes that then rate of film build is 1nm/ more than second, is preferably 10nm/ more than second, enters to prevent impurity.
Perhaps containing under the interpolation element situation of wanting more than 1 atom %, wishing that rate of film build is 10nm/ more than second, sneaks into the impurity that prevents to add as far as possible.
Also there are membrance casting condition and impurity level irrelevant and to the influential situation of grain size.For example, in Al, sneak into the alloy film that the Ta about 2 atom % constitutes, be mixed with the amorphous state phase at intercrystalline, and crystallization phase depends on membrance casting condition with amorphous state ratio mutually.For example, sputter under low pressure, then the crystalline portion ratio increases, and specific insulation reduces, and pyroconductivity increases.
Manufacture method or sputter gas (Ar, Ne, Xe etc.) that impurity composition in the film or crystallinity also depend on the alloys target that sputter is used.
Like this, the specific insulation of filminess is not only by metal material and form and decide.
In order to obtain high thermoconductivity, as mentioned above, preferably to reduce impurity level, but then, Al or Ag simple metal have corrosion stability and anti-foreign matter to separate out the tendency of poor performance, therefore will consider to take into account both and decide best the composition.
Certainly, in order to obtain high thermal conductivity and high reliability, it also is effective that sandwich construction is made in the reflection horizon.At this moment formation is that at least 1 layer is as having the above-mentioned low volume resistivity material of 50% above thickness of total reflection layer thickness.In fact finish heat sinking function, other layer then helps to improve corrosion stability, separates out performance with the stickability and the anti-foreign matter of protective seam.
More particularly, the Ag that has high thermoconductivity and low specific insulation in the metal not quite can be compatible with the protective seam that contains S, and deterioration is fast slightly under situation about rewriteeing repeatedly.
In hot and humid being accelerated into the tendency that is corroded is easily arranged under the experimental enviroment again.
Therefore, adopt Ag and Ag alloy, and the Al that is provided with below the above 100nm of 1nm is that the alloy-layer conduct of principal ingredient and the contact bed between the upper protective layer also are effective as low volume resistivity material.If thickness adopts more than the 5nm, then thin layer is not the island structure, evenly forms easily.
As the Al alloy,, can enumerate the Al alloy that for example comprises following Ta, Ti, Co, Cr, Si, Sc, Hf, Pd, Pt, Mg, Zr, Mo or Mn of the above 2 atom % of 0.2 atom % with noted earlier the same.
Interfacial layer thickness is during less than 1nm, and the protection effect is insufficient, if surpass 100nm, has then sacrificed radiating effect.
Be under the situation of Ag or Ag alloy particularly, use contact bed effective especially in the reflection horizon.This is because Ag contacts with containing the protective seam that the present invention wishes the sulfide that adopts, causes corrosion than being easier to because of sulfuration.
And when adopting Ag alloy reflection horizon and Al alloy interface layer, because Ag is mutual to a pair of combination that is easier to spread with Al, therefore better is to make the interface oxide layer of Al surface oxidation formation greater than 1nm.Interface oxide layer particularly surpasses 10nm if surpass 5nm, then forms thermal resistance, suffer damage as the reflection horizon function with fabulous thermal diffusivity of original intention, and be unfavorable therefore.
Multilayer is made in the reflection horizon, with high volume resistivity material and the combination of low volume resistivity material, is effectively for obtaining desirable area resistivity at desirable thickness.
Come adjusted volume resistivity by alloying,, also constitute the manufacturing cost of target and then the starting material of medium and compare a key factor that rises though can use alloys target to simplify sputtering process.Thereby it also is effective method to obtain desirable specific insulation that the film of pure Al or pure Ag film and above-mentioned interpolation element itself is formed sandwich construction.
If the number of plies reaches about 3 layers, though then initial installation cost increase sometimes, the cost of every medium is turned one's coat and can be suppressed.
Preferably the reflection horizon is made the reflection multilayer layer that is made of metal multilayer film, all thickness are made below the above 30nm of 40nm, the reflection multilayer layer thickness be metal film layer (also can be multilayer) below the above 150n Ω of the 20n Ω m m 50% or more.
Recording layer and protective layer thickness; except the restriction of considering above-mentioned thermal property, physical strength, reliability aspect; also will consider the interference effect of coming with sandwich construction, it is big with the contrast of recording status not that thickness selects to make that the amplitude of laser absorption excellent in efficiency, tracer signal is a recording status.
For example,, and guarantee and the interchangeability of digital versatile disc-ROM, then must improve degree of modulation if medium of the present invention are used for erasable DVD.The tracking servo method that is called DPD (DifferentialPhase Detection, i.e. differential phase detection) method that must intactly use common walkman to adopt again.
DC replay signal (replay signal that contains DC component) waveform when Figure 6 shows that the random signal of record, playback EFM enhancement mode modulation.Degree of modulation is with the maximum signal Itop and the signal amplitude I of 14T spot 14Ratio I 14/ Itop defines.
In fact Itop is equivalent to the interior reflectivity of groove of non-recorded part (crystalline state).I 14Then reflect the crystalline state part of phase change media and the problem of catoptrical intensity difference of amorphous portion and phase differential.
Catoptrical intensity difference is decided by crystalline state and amorphous reflection differences basically, if the degree of modulation behind the above-mentioned record is about more than 0.5, then can realize low beating, the simultaneously above-mentioned also action well of tracking servo that utilizes the DPD method.
Figure 7 shows that the calculated example of 4 layers of structure reflection differences of typical case.Be that (ZnS) is set on polycarbonate substrate 80(SiO 2) 20Protective seam, Ge 0.05Sb 0.69Te 0.26Recording layer, (ZnS) 80(SiO 2) 20Protective seam, and Al 0.995Ta 0.005The structure in reflection horizon.
Each layer refractive index adopts measured value.The complex index of each material is under wavelength 650nm condition; last lower protective layer is 2.12~0.1i, and the reflection horizon is 1.7~5.3i, and substrate is 1.56; it is 3.5~2.6i that recording layer (is just measured under the state after the film forming) when amorphous state, and the crystalline state after the initialization is 2.3~4.1i.
Again, the thickness in recording layer, the 2nd protective seam and reflection horizon is respectively 18nm, 20nm and 200nm, gets fixed value.
Only see and the relation of the 1st protective seam thickness that oscillation amplitude change is little usually, with denominator Itop, be that the reflectivity of crystalline state has very confidential relation.Thereby the crystalline state reflectivity is preferably low as far as possible.
In the calculated example of Fig. 7, the 1st protective seam is (ZnS) of refractive index n=2.12 80(SiO 2) 20Film, at this moment, the 1st minimal value d 1Be thickness 50~70nm, the 2nd minimal value d 2Be thickness 200~220nm.Cyclical variation later on.
If the high recording layer of reflectivity, then minimum the 1st protective seam thickness only actually of crystalline state reflectivity is by the refractive index decision of protective seam.If the minimal point thickness of other refractive index ns is to d 1And d 2Multiply by 2.1/n, then approximate can obtaining.Usually, the dielectric that is used as protective seam is about n=1.8~2.3, d 1Be about 60~80nm.
If the 1st protective seam refractive index n is less than 1.8; then owing to the reflectivity at minimal point increases; degree of modulation significantly descends, and less than 0.5, is unfavorable therefore; otherwise; if surpass 2.3, then, can not reach 20% because the reflectivity of minimal point is low excessively; therefore focus servo and tracking servo difficulty also are not suitable for.
In the compositing range of recording layer of the present invention, can bring into play basic similarly optical characteristics with Fig. 7.
From the viewpoint of production efficiency, the 1st protective seam thickness preferably is limited to below the 150nm.This be because, the dielectric protective seam film forming speed that utilizes sputtering method now is 15nm/ second at most, its film forming is if need more than 10 seconds, then cost will rise.In addition, because the allowed band of Thickness Variation is relatively stricter, so production efficiency is undesirable.That is to say, as shown in Figure 7, if with desirable thickness d 0Depart from △ d, then at the 1st minimal value d 1Near the 2nd minimal value d that reaches 2Near, reflectivity all changes identical numerical value.
On the other hand, in the manufacturing homogeneity limit of film thickness distribution normally with respect to d 0± 2~3%.Thereby, d 0Thin more, Thickness Variation amplitude △ d is more little, can suppress in the disc face or the reflectance varies between the disc, is favourable therefore.
Thereby, to the type sputter equipment, there is not the device of substrate rotation, revolution mechanism for low-cost static phase, preferably adopt the 1st minimal value d 1Near thickness.
On the other hand, the substrate surface distortion when thick protective seam rewrites repeatedly for inhibition has very big effect, therefore if focus on that improvement rewrites permanance repeatedly, then preferably adopts near the thickness of the 2nd minimal value d2.
In the such medium that write down by substrate incident recording playback light or reset, must make the 1st protective seam that to a certain degree thickness is arranged, the influence of the heat that is produced when exempting from record with protective substrate.Though recording layer is about 100 nanoseconds when record but reaches more than 500~600 ℃.Therefore, thickness is preferably more than the 50nm.Under situation,, be easy to generate noise and defective etc. if record repeatedly then gathers microdeformation on the substrate less than 50nm.It is particularly important when particularly substrate is thermoplasticss such as polycarbonate.
The following describes the desirable optic recording method that uses with these medium.
The first desirable recording method is when utilizing multiple record spot length that spot length modulated information is write down on above-mentioned recording medium,
Irradiation can make the recording light of the erase power Pe of amorphous state crystallization between the record spot,
When the time span of a record spot is nT (T is the reference clock signal cycle, and n is the integer more than 2).
The time span nT of record spot is divided into successively
η 1T、α 1T、β 1T、α 2T、β 2T……、
αiT、βiT、……αmT、βmT、η 2T
(in the formula, m is that number is cut apart in pulse, and m=n-k establishes the integer that k is 0≤k≤2.
Establish ∑ again, ii+ β i)+η 1+ η 2=n, η 1Be the real number of η 〉=0, η 2Be η 2〉=0 real number, 0≤η 1+ η 2≤ 2.
If α i(1≤i≤m) is α i0 real number, β i(1≤i≤m) is β i0 real number, ∑ α i<0.5n.
If α i=0.1~1.5, β i=0.3~1.0, β m=0~1.5, α i=0.1~0.8 (2≤i≤m).
And in the i of 3≤i≤m, establish α i+ β I-1=0.5~1.5 scope, and irrelevant with i, be a fixed value.
At α i(1≤i≤m) is in the time, and irradiation is enough to make the recording power Pw of recording layer fusion, and (recording light of Pw 〉=Pe) is at β for T i(1≤i≤m) is in the time, and the recording light (relation that 0<Pb≤Pe can be arranged) of the bias power Pb of 0<Pb≤0.2Pe is satisfied in irradiation here, in β mT for T.
By adopting this recording method with above-mentioned medium, cooling velocity when correctly the controlling recording layer solidifies again, at least in 3m/s arrives the linear velocity scope of 8m/s, and utilize the method for setting recording condition, can in the very wide linear velocity scope of 1m/s to 15m/s, carry out the shortest spot length and be the high density spot length modulated record below the 0.5 μ m, can reach the number of rewrites repeatedly more than 1000 times, can realize beating less than the low of reference clock signal cycle 10%.
At first, in order to realize above-specified high density spot length modulated record, making the laser beam of wavelength 350~680nm is that the object lens below 0.9 focus light on the recording layer more than 0.55 by numerical aperture NA, obtains the luminous point of small focused beam.
Preferably making NA is more than 0.55 below 0.65, if NA surpasses 0.65, then because the influence of the aberration that inclined light shaft produces becomes greatly, must make the distance of object lens and record surface extremely approaching.Thereby when the substrate incident focused beam by 0.6mm left and right thicknesses such as DVD, NA is about 0.65 to be the upper limit.
Then, as shown in Figure 8, by recording optical power being modulated at least 3 values, the linear velocity surplus in the time of can relaxing power headroom and record.
In Fig. 8, foremost recording impulse α iThe starting position of T the and backmost end position of break impulse β mT not necessarily must be consistent with the starting position and the end position of original tracer signal.At 0≤η 1+ η 2In≤2.0 the scope, η can be set up front 1T, in the end face is provided with η 2T.According to spot length before and after this spot and the length between spot, to η 1T and η 2The length of T is finely tuned, and also is effective for correct formation spot.
Perhaps also have corresponding to spot length nT only to change β m, can form the situation of good spot with this.Also can make last β m=0.For example, in EFM modulation, the 11T spot in the spot of 3T~11T, or in the modulation of EFM enhancement mode the isometric spot of 14T spot in the spot of 3T~14T, be such easy savings heat, therefore preferably prolong last β m, to prolong cool time.
Otherwise, under short spot situations such as 3T spot, preferably shorten β m.It adjusts width is about 0.5.If surpass the high density recording of the line density of so-called DVD degree, also can obtain enough good tracer signal quality even then not necessarily carry out such fine setting.
By changing the size of bias power Pb, also can control spot shape again.Figure 9 shows that irradiation during two recording impulses any temperature of recording layer one of change example in time.Be with respect to medium relatively move light beam, simultaneously when Continuous irradiation recording impulse P1, break impulse and recording impulse P2, in the locational temperature variation of irradiation recording impulse P1.(a) is the situation of Pb=Pe among the figure, (b) is the situation of Pb ≈ 0.
(b) among Fig. 9, because the bias power Pb in break impulse interval is almost 0, so TL ' is reduced to low-down point from fusing point, and cooling velocity midway is also big.Thereby the amorphous state spot fuses when recording impulse P1 shines, when break impulse thereafter owing to chilling forms.
On the other hand, in Fig. 9 (a), also shine erase power Pe in the break impulse interval, therefore the 1st the postradiation cooling velocity of recording impulse P1 is slow, because the temperature in the break impulse interval descends, the minimum TL temperature that reaches rests near the fusing point Tm, because follow-up recording impulse P2 effect is heated near the fusing point Tm, is difficult to form the amorphous state spot again.
For medium of the present invention, get the precipitous temperature distribution history shown in Fig. 9 (b) for the crystallization that suppresses the high-temperature region, it is very important obtaining good amorphous state spot.This be because, the recording layer of medium of the present invention only demonstrates big crystallization rate in the high-temperature region that is slightly less than fusing point, therefore get the distribution curve of (b), this is the distribution curve that the recording layer temperature does not stop at the high-temperature region basically, it is believed that to suppress to recrystallize with this.
Perhaps, at lower low-temperature space near Tc Tc, it has not been dominating role that nucleus is created on each erase process, because the Sb atomic group stable existence that can constitute nucleus that forms during aforementioned initialization can think that also only the crystal growth of high-temperature region plays dominating role.
Thereby, by control cooling velocity and TL ', can almost completely suppress to recrystallize, obtain having the almost consistent amorphous state spot that clear outline is arranged with melt region, can reduce beating of spot border.
On the other hand, for GeTe-Sb 2Te 3Pseudo-two mischmetals adopt the arbitrary temperature distribution history in the (a) and (b) among Fig. 9, and the amorphous state dot formation process does not have marked difference yet.This is because this material is than wider temperature range, particularly near the low-temperature space of Tc Tc, the crystallization again that the speed that demonstrates is slow slightly.Or this material becomes constant rate of speed relatively generating with crystal growth near the humidity province of Tm near the nucleus of the humidity province of Tc, therefore also can think, than wider temperature range, recrystallizing than low velocity is taken place as a whole.
For GeTe-Sb 2Te 3, employing Pb<Pe is also arranged.And the break impulse that uses to be suppressing the situation of coarse grain, but if get Pb/Pe≤0.2, then crystallization is subjected to too much inhibition near Tc, wipes performance and descends on the contrary.
But, for recording layer material of the present invention, it is believed that and do not carrying out basically near the crystallization under the lower temperature of Tc, therefore preferably get Pb/Pe≤0.2.Perhaps more particularly, get 0≤Pb≤1.5 (mW), as long as tracking servo is stable, preferably adopt low Pb, chilling utilizes break impulse so energetically as far as possible, just can clearly form the border of amorphous state spot.
In the pulse dividing method of Fig. 8, particularly only make top recording impulse α iT is than succeeding impulse α iT is long, only sets foremost and rearmost break impulse width beta again iT and β mT are different with other break impulses, and this is the most effective for the balance that obtains long spot and short spot performance.
Top pulse α iT is not because there is the waste heat effect, and heating up needs the long slightly time.Perhaps, must also be effective than succeeding impulse height the determining recording power of top pulse.
Again, pulse switching and clock signal period T are synchronous as if making, and then pulse control becomes simple.Being suitable for spot length modulated record and the simple pulse dividing method of pulse control circuit is shown among Figure 10.Pulse dividing method during (a) for record spot length modulated data (b) is the situation (c) of m=n-1, is the situation of m=n-2.And in (b), (c), simple in order to make figure, omitted T.If all α among the figure i(2≤i≤m) and β i(2≤i≤m-1) all has with i irrelevant, is certain value, gets α i〉=α i, α i+ β I-1=1.0 (3≤i≤m), and make α i(the back edge of the recording impulse of 2≤i≤m) is synchronous with time clock.
Again, make Pb identical, also help circuit reduction with playback luminous power Pr.Only make foremost pulse α iT is longer than succeeding impulse, and this is necessary for make the short spot and the fine balance of record of long spot in so-called eye pattern (eye pattern).Perhaps also can only make the power ratio succeeding impulse height of front pulse.
Such pulse utilizes 3 kinds of gate signal generation circuit shown in Figure 11 and determines the method for the priority between them just can access.
Figure 11 is the key diagram that utilizes one of the pulse generating method example of recording method of the present invention.
(a) being clock signal, (b) is data-signal, and the gate signal that is produced by 3 kinds of gate signal generation circuit in the recording impulse generation circuit is that (c) Gate1, (d) Gate2 reach (e) Gate3.By being predetermined the priority of these 3 kinds of gate signals, just can realize pulse dividing method of the present invention.
Gate1 only determines α between the recording impulse generating region iT, the Gate2 decision produces the succeeding impulse α of regulation number iT (the moment of 2≤i≤m).Here establish pulse width α iIn 2≤i≤m certain value α c.Gate3 produces β between the break impulse generating region iT.During Gate3 conducting (high level), produce Pb, when ending (low level), produce Pe.
Only α iRise time and pulse width determine separately, can make β iGet and β iDifferent values.
Preferably make the rising edge of Gate3 and Gate1 synchronous, Gate1 and Gate2 produce Pw respectively, and when Gate1 and Gate2 conducting, Gate3 is preferential.If T time delay of regulation Gate1 1Be α i, be α c the time delay of Gate2 (T1+T2), then can stipulate the strategy of Figure 10.
Here if establish T 1More than 1T, then become the pulse under m=n-1 situation of Figure 10 (b), if be made as less than 1T, succeeding impulse deducts a number, then becomes the pulse under m=n-2 situation of Figure 10 (c).At this moment, make α iT and β M-2Than m=n-1 duration, so that the spot length that forms is nT.
As application examples of the present invention, for the identical or higher recording density of read-only DVD under obtain the signal quality identical with read-only DVD, preferably adopt following recording method.
Just to utilize numerical aperture NA be 0.55~0.9 object lens with wavelength is the optic recording method that the light of 350~680mn focuses on the enterprising line data recording playback of recording layer, establishes m=n-1 or m=n-2,0≤Pb≤1.5 (mW), and Pe/Pw is more than 0.3 below 0.6.And preferably establish
α i=0.3~1.5,
α i≥α i=0.2~0.8(2≤i≤m),
α ii-1=1.0(3≤i≤m),
βm=0~1.5,
It must be for when power produces change that the ratio of Pe/Pw is kept, and when the high-power spot of record down is big, also erase power is strengthened, to enlarge the scope that may wipe.When Pe/Pw less than 0.3 the time, usually because Pe is low, wipes and be not easy thoroughly.Otherwise if greater than 0.6, then Pe is too much, causes the decrystallized once again of beam center easily, is difficult to utilize perfect recrystallizationization to wipe.Again, shine in the energy of recording layer excessive, also easily because of the pernicious deterioration of following of rewriting repeatedly.
The recording layer that the present invention forms is because α iIn especially little scope, can obtain less beating, therefore preferably get ∑ α i<0.5n, K is more little to make (∑ α more i)/n reduces.(∑ α when promptly being preferably in K=0 or K=1 i)<0.4n, during k=2, (∑ α i)<0.5n.
For such recording impulse dividing method being used for the rewriting more than the linear velocity 3m/s, at recording layer Ge of the present invention x(Sb yTe 1-y) 1-xIn, preferably y gets more than 0.72, and for the rewriting more than the linear velocity 7m/s, preferably making y is more than 0.74.That is the Sb/Te ratio gets more than 2.57, and preferably the rich Sb that gets more than 2.85 of Sb forms.
Form even the recording layer composition is made this rich Sb, the stability of amorphous state spot and storage stability are still better, and this is a desirable feature of the present invention.
In 8-No. 22644 communiques of Japanese patent laid-open, put down in writing at Sb 0.7Te 0.3The AbInSbTe recording layer that adds the Ag that amounts to about 10 atom % and In in contiguous the composition and form.But in this AgInSbTe recording layer, if making the Sb/Te ratio is more than 2.57, then the amorphous state spot is extremely unstable, the storage stability existing problems.
Below with experimental example comparative descriptions in addition.Consider such record case, promptly when carrying out the spot length records of EFM enhancement mode modulation, for the spot of record length nT, on-line velocity is in the scope of 2m/s~5m/s, adopt the optical system of wavelength 630~680nm, NA=0.6, recording impulse is divided into n-1 carries out record.
As one of recording layer of the present invention example, adopt Ag 0.05Ge 0.05Sb 0.67Te 0.23(Sb/Te ≈ 2.91), and, adopt Ag as one of above-mentioned AgInSbTe recording layer example 0.05In 0.05Sb 0.63Te 0.27(Sb/Te ≈ 2.33).
Therefore recording layer and above-mentioned AgInSbTe recording layer that the present invention forms, its optical constant adopt identical layer structure about equally, can access identical reflectivity and degree of modulation, thereby can adopt layer structure identical on the calorifics.
Getting the 1st protective seam thickness is 100nm, and recording layer is 20nm, the 2nd protective seam 20nm, and the reflection horizon is 200nm, and all gets β iAbout=0.5 (1≤i≤n-1), Pw=10~14 (mW), Pe/Pw=0.5, Pb ≈ 0.
At this moment, to existing Ag 0.05In 0.05Sb 0.63Te 0.27Recording layer, preferably α i=0.8~1.2, α i=0.4~0.6 (2≤i≤n-1).α particularly i=1.0, α i=0.5 (2≤i≤n-1), under the situation of β m=0.5, ∑ α iIrrelevant with n, be 0.5n.
And for Ag of the present invention 0.05In 0.05Sb 0.67Te 0.23Recording layer, best scope is α i=0.3~0.5, α i=0.2~0.4 (2≤i≤n-1).More particularly, can make α i=0.6, α i=0.35 (2≤i≤n-1).In this case, when n=3, ∑ α i≈ 0.32n; And n=4 is when above, ∑ α i≈ 0.33n~0.34n.
That is to say that this shows in medium of the present invention, the average irradiation power of irradiation in the time of can reducing to write down, reducing actual recording impulse irradiation time is ∑ α i<0.4n.
Can obtain following effect in view of the above.
(1) can reduce because the decline of the tracer signal quality that the high power record causes.The problem of high power record results from, and the luminous energy that gives recording layer too much is full of recording layer.Therefore, cooling velocity is slow, and recrystallizing of amorphous state spot taken place, and perhaps making repeatedly, overwrite performance significantly descends.
By lower powered break impulse interval being set to suppress Mean Input Power, and utilize the reflection horizon of high thermoconductivity to dispel the heat to in-plane, even like this when high power writes down, also can suppress the baneful influence that spot rear end part, the particularly heat accumulation of long spot rear end part cause, can form good long spot.
(2) can alleviate the fire damage of each layer when rewriteeing repeatedly, improve rewriteeing permanance repeatedly.By reducing each fire damage, can suppress for example distortion of the plastic base of poor heat resistance.Can also hinder the scope reach to hurt be limited in the narrower and small scope of core of laser beam profiles.
Particularly be easy to generate the above long spot of n=4 of heat accumulation more, make physical record energy exposure ratio (∑ α 1The effect that)/n reduces is big more.Even thereby under the following low linear velocity of the 5m/s that is subjected to fire damage easily, also can alleviate baneful influence to medium.
In the present invention, can improve rewriteeing permanance repeatedly like this, reach than the number of rewrites of high 1 order of magnitude in the past.
Also have, recording layer adopts with Ge x(Sb yTe 1-y) 1-xAlloy is the film (0.045≤x≤0.075,0.74≤y<0.8) of principal ingredient, utilizes according to linear speed degree of one-tenth to change the recording impulse dividing method, can rewrite with the linear velocity of the wide range that comprises 3m/s~8m/s.
That is to say that in the pulse dividing method of Fig. 8, the k of m=n-k gets certain value, the linear velocity during rewriting is low more, makes Pb/Pe or α iA certain dull the minimizing.
Also have,, also can change clock signal period corresponding to linear velocity as required, or change Pw, Pe to keep best under the linear velocity separately in order to keep certain call wire density.
In the present invention, also providing a kind of 1 times of speed and two kinds of the shortest spot length of condition record of 2 times of speed with dvd standard playback linear velocity is the method for the so-called EFM enhancement mode modulation signal of 0.35~0.45 μ m.And the standard weight payingoff speed of DVD is 3.49m/s.
That is to say that described optic recording method is that to utilize numerical aperture NA be 0.55~0.65 object lens, making wavelength is that the light of 600~680nm focuses on the recording layer by substrate, and getting the shortest spot length is 0.35~0.45 mu m range, the method for carrying out the data recording playback,
Described optic recording method is to establish
N is 1~14 integer,
m=n—1,
Pb is irrelevant with linear velocity in the scope of 0≤Pb≤1.5 (mW), gets certain value,
Pe/Pw can be corresponding to change of line speed in 0.4~0.6 scope,
(i) in line speed record is the scope of 3~4m/s, establishing the reference clock cycle is T0,
α i=0.3~0.8,
α 1〉=α i=0.2~0.4, irrelevant with i, get certain value (2≤i≤m),
α 2i≥1.0,
α ii-1=1.0(3≤i≤m),
βm=0.3~1.5,
At α iT (the time internal radiation recording power Pw of 1≤i≤m) 1Recording light,
(ii) in line speed record was 6~8m/s scope, establishing the reference clock signal cycle was T 0/ 2,
α’ 1=0.3~0.8,
α ' 1〉=α ' i=0.3~0.5, irrelevant with i, get certain value (2≤i≤m),
α’ i+β’ i-1=1.0(3≤i≤m),
β’ m=0~1.0,
At α i(in the time of 1≤i≤m), the irradiation recording power is Pw to T 2Recording light the time be
α’ ii(2≤i≤m),
0.8≤Pw 1/Pw 2≤1.2。
According to present inventor's experiment,, utilize this setting can access especially little beating as long as adopt the pulse dividing method of Figure 10.
Here, if also establish α 2+ β 1=1.0, then relevant with pulsewidth independent parameter is α 1, α iAnd these 3 parameters of β m, can further simplify the tracer signal source, be very desirable.
Also have, n there is no need to get all integers of from 1 to 14, in the modulation of EFM enhancement mode, gets 3 to 11 and 14.Also can use (1,7) RLL-NRZI (Run Length Limited-Non Return To Zero Inverted; Be limited run-length code-IBM formula non return-to-zero code) sign indicating number etc.
In addition, be certain value in order to make recording density, when the clock signal period when generally setting 1 times of speed recording is 2 times of speed recordings 2 times.
Also have, the present invention not only keeps mode (the Constant linear velocity that certain linear velocity one writes down in the face of whole record surface for aforesaid one side, the CLV mode, be the constant linear velocity mode) produce effect, and only for the mode that writes down in whole recording areas with certain angular velocity of rotation (Constant angular velocity, CAV mode, i.e. constant angular velocity mode) also effective.Perhaps, for radial direction being divided into a plurality of zones, the ZCLV that rewrites by the CLV mode in the same area (Zoned CLV, promptly regional Constant Linear Velocity) mode is also effective.
Cd diameter has 86mm, 90mm (simple CD size), 120mm (CD size) or 130mm etc. various, and recording areas is nearly 65mm from radius 20~25mm to maximum.At this moment the linear differential maximum of Internal and external cycle is near 3 times.
Usually, in high density spot length records, the linear velocity scope that phase change media demonstrates good rewriting characteristic is that linear velocity is than the scope about 1.5 times.If linear velocity is fast, then because the recording layer cooling velocity is fast, so form the amorphous state spot easily, but remain in the above time weak point of Tc, wipe difficulty.On the other hand,, then wipe easily, but, therefore recrystallize easily, be difficult to form good amorphous state spot because the recording layer cooling velocity is slow if linear velocity is slow.
In order to address this problem, can Internal and external cycle reflection horizon thickness be changed by regulating, make the radiating effect degree in inner ring reflection horizon increase.Perhaps also have such scheme, promptly change recording layer and form,, or reduce the necessary critical cooling rate of inner ring formation amorphous state with the crystallization rate of raising outer ring.But it is not easy will making the disc of making have such distribution.
On the other hand, if medium of the present invention and optic recording method are used in combination, if be that maximum line velocity is below about 10m/s in disc outmost turns linear velocity, even then employing CAV mode or ZCLV mode also can be carried out good record.
For the present invention being used for changing according to radius as mentioned above the medium of linear velocity, preferably recording areas is divided into a plurality of zones according to radius, the reference clock frequency of data and pulse dividing method are switched be used in each zone.
That is to say, be that the optic informating recording medium with regulation recording areas is rotated with a fixed angular speed, and utilize the method for multiple spot length records information, make the rotation of this medium so that the linear velocity of the inner ring of recording areas is 2~4m/s, the linear velocity of recording areas outmost turns is 6~10m/s, this recording areas is made of a plurality of zones of cutting apart by radius, changes the reference clock signal period T according to the average linear velocity in each zone, and recording density is roughly necessarily.
At this moment, getting pulse, to cut apart several m be certain value and irrelevant with the zone, make from outer collar region to inner circle area Pb/Pe than and/or α i(i is at least 1 among 1≤i≤m) dullness reduces.Inner round portion in low linear velocity can prevent to take place because of cooling velocity makes the incomplete situation of formation of amorphous state spot inadequately like this, and in addition, so-called dullness reduces α i(i is at least 1 among 1≤i≤m) is meant for example at α 1, α 2, only make α among the α m 2Reduce.
More particularly, hope can be adopted the circuit of simplifying the variable pulse dividing method according to the pulse dividing method of linear velocity based on pulse dividing method shown in Figure 10.At this moment, recording areas is divided into P zone along radial direction, each regional clock signal period and pulse dividing method are changed, this wants simple compared with it is changed.
In the present invention, recording areas is divided into P zone according to radius, will inner ring one side as the 1st zone, as the P zone, if the angular velocity of establishing in the q zone (q is the integer of 1≤q≤p here) is ω q, average linear velocity is<Vq with outmost turns one side〉ave, maximum line velocity is<Vq〉max, minimum line speed is<Vq〉min, the reference clock signal cycle is Tq, the shortest spot time span is n MinTq, then best
<Vp〉ave/<V 1Ave is 1.2~3 scope,<Vq〉max/<Vq〉min is below 1.5.In the same area, adopt identical clock signal period and identical pulse dividing method, but the limit of the linear velocity scope that can cover with identical pulse dividing method is about 1.5 times.
So, in the same area, ω q, Tq, α i, β i, Pe, Pb and Pw be certain value, the shortest spot physical length n MinTq<Vq〉ave is below the 0.5 μ m, Tq<Vq〉ave is approximately certain value for all q of 1≤q≤p, and
M=n-1 or m=n-2,
α i=0.3~1.5,
α 1≥α i=0.2~0.8,(2≤i≤m),
α ii-1=1.0(3≤i≤m),
0≤P≤1.5(mW),
0.4≤Pe/Pw≤0.6,
Be easy to act as most in the formula at m=n-1 o'clock, α 1=0.3~1.5, α i=0.2~0.5; When m=n-2, α 1=0.5~1.5, α i=0.4~0.8.
The pulse dividing method importantly changes according to following rule.In each zone, Pb, Pw, Pe/Pw ratio, α i, β i, β m is variable, makes α at least from the inside collar region of outer collar region i(i is at least 1 among 2≤i≤m) dullness reduces.
The α that each is regional iVariation best with 0.1T be at interval or 0.01T carry out at interval.
Here, by the high frequency basic clock signal generation circuit of additional phase, can produce Tq and editing pulse length as the All Ranges of the multiple of this high frequency basic clock signal for 1/100 left and right sides cycle of outmost turns reference clock signal period T p.
In DVD,, therefore adopt the high frequency basic clock signal frequency that is up to about 2.6GHz and high frequency basic clock signal frequency about the 260MHz of normally little 1 order of magnitude is just enough because the reference clock signal frequency of 1 times of speed is about 26MHz.
Moreover the maximal value of establishing the Pw of this recording areas is Pwmax, and minimum value is Pwmin, then can make Pwmax/Pwmin≤1.2, Pe=Pw=0.4~0.6,0≤Pb≤1.5 (mW).In view of the above, the setting range of 3 kinds of power can be limited, therefore power generation circuit can be simplified.
In the present invention, can also by set Pw, Pe/Pw when Pb be certain value, and only change the pulse dividing method, with corresponding all linear velocities.Can also set β m is and the irrelevant certain value in zone, and only with α iAnd α mBe set at the parameter relevant with the zone.This is exceedingly useful for the recording impulse control circuit of simplifying driver.
In the present invention, also can according to when record laser head radial location information on recording medium, set imaginary area and carry out record, also can be according to the address information or the area information of record are provided with concrete areal structure on disc in advance on the disc, imaginary zone might as well, concrete zone is as long as select and the regional corresponding recording impulse method of linear velocity that determines.
The following describes other examples that optic recording method of the present invention are used for the ZCAV mode.
Recording areas is divided into p zone according to radius, will inner ring one side as the 1st zone, with outmost turns one side as the p zone, if the angular velocity in q zone (q is the integer of 1≤q≤p here) is ω q, average linear velocity is<Vq〉ave, maximum line velocity is<Vq〉max, and minimum line speed is<Vq〉min, the reference clock signal cycle is Tq, and the shortest spot time span is n MinTq.
In the ZCAV mode, shift to the zone of outer ring part more, must reduce the Tq of the reference clock signal of record data more, make call wire density be roughly certain value.
That is to say, in order to make Tq<Vq ave is roughly certain value with respect to all q of 1≤q≤p, change Tq corresponding to zones of different.Here what is called is roughly certain value, is to include ± about 1% error.
In addition, in order to make maximum line velocity in the same area and minimum line speed within the specific limits, the regional roomy degree of decision will satisfy following formula, promptly
(<Vq>max—<Vq>min)/(<Vq>max+<Vq>min)<10% (2)
That is to say, make (<Vq〉max-<Vq〉min) allow to reach mean radius<rq less than the width in 10%, the q zone of (<Vq〉max+<Vq〉min)〉ave ± radial location below 10%.Preferably (<Vq〉max-<Vq〉min) be (<Vq〉max+<Vq〉min) 5% less than.
Peak width can be cut apart recording areas by each radius five equilibrium, as long as but satisfy this condition, also can not that five equilibrium is cut apart.Region quantity is different because of the recording areas width, but for the recording areas of 30~40mm width, roughly is divided into 10 more than the zone.
According to present inventor's research, even the shortest spot length is about 0.4 μ m, if satisfy (2) formula, then jitter values also can reach realistic scale.
More than two conditions be in order to make call wire density certain and then make spot physical length or the certain condition of channel bit length.In addition, so-called channel bit length is the length along each information bit of recording channel.
In order to obtain the playback interchangeability with DVD more reliably, when establishing benchmark playback speed V for about 3.5m/s, reference clock signal period T during for about 38.2nsec, the variation that preferably makes channel bit length VT is less than pact ± 1%.
In the ZCAV medium,, must satisfy following (3) formula, promptly in order to satisfy this condition
(<Vq>max-<Vq>min)/(<Vq>max+<Vq>min)<1% (3)
That is to say, make (<Vq〉max-<Vq〉min) allow to reach average half all<rq less than the width in 1%, the q zone of (<Vq〉max+<Vq〉min) radial location below 1% of ave.Therefore, recording areas is divided into zone more than 200.And
Tq<Vq>ave=vT,
Tq<Vq〉ave is roughly certain value with respect to all q of 1≤q≤p.Here what is called is roughly certain value, is to comprise ± about 1% error.
Like this,,, therefore also can reset, improve the interchangeability of CLV mode and DVD player with the CLV mode owing to can carry out and the irrelevant accurate isodensity record of radius though be the ZCAV mode.
As required, also can make peak width narrower.
The following describes the optic recording method that obtains under these conditions with DVD identical recordings density.
Utilizing numerical aperture NA is that to make wavelength be that the light of 600~680nm is when focusing on the enterprising line data recording playback of recording layer by substrate for 0.55~0.65 object lens, the inner ring of above-mentioned recording areas is in radius 20~25mm scope, outmost turns is in radius 55~60mm scope, the average linear velocity in territory, inner ring one lateral areas is 3~4m/s, if the angular velocity of getting in the q zone (q is the integer of 1≤q≤p here) is ω q, average linear velocity is<Vq〉ave, maximum line velocity is<Vq〉max, minimum line speed is<Vq〉min, the reference clock signal cycle is Tq, and the time span of short spot is n MinTq, then
N is 1~14 integer,
m=n—1,
ω q, Pb and Pe/Pw and zone are irrelevant, are certain value,
Tq<Vq〉ave is roughly certain value with respect to all q of 1≤q≤p, and satisfies the relation of following formula:
(<Vq>max-<Vq>min)/(<Vq>max+<Vq>min)<10%
(i) be located in the first area
α i 1=0.3~0.8,
α i 1〉=α i 1=0.2~0.4, irrelevant with i, for certain value (2≤i≤m),
α i 2i 1≤1.0
α i 1i i-1=1.0(3≤i≤m),
(ii) be located in the p zone
α p i=0.3~0.8,
α p i〉=α p i=0.3~0.5, irrelevant with i, for certain value (2≤i≤m),
α p i+ β p I-1=1.0 (3≤i≤m), at this moment,
(iii) be located in other zone α i 1≤ α q 1≤ α p 1(2≤i≤m), α i 1As α i 1With α p 1Between value record.
The inner ring of above-mentioned recording areas is in the scope of radius 20~25mm, and outmost turns is in radius 55~60mm scope, in this case the wide about 30~40mm of the radius of recording areas.And disc is rotated with constant angular velocity, make in inner ring the 1st zone<V 1Ave=3~4m/s.
Carry out record for the 1st zone and p zone according to above-mentioned condition,, establish α for other zones (the q zone of 2≤q≤p-1) i 1≤ α q 1≤ α p 1(2≤i≤m), α q 1Be α i 1With α p 1Between value, in this case, α q 1Value preferably set with the interval of 0.1T or 0.01T.
Best α i 1〉=α q 1〉=α p 1(α in the formula i 1α p 1).
Moreover, as if Pb, Pe/Pw, β i, β m is irrelevant with the zone, is certain value, only makes α 1And α iBecause of the zone changes, then can in the very wide linear velocity scope of whole linear velocity 3~8m/s, obtain good rewriting characteristic.
Preferably these Pe/Pw, Pb, Pw, β m, (α i 1, α p 1), (α i c, α p c) numerical value utilize the distortion of pre-pit string or groove to be recorded on the substrate in advance, like this, each recording medium is also had each zone, and driver can be selected only pulse dividing method and power, and these numerical value are recorded in recording areas and position adjacent inner ring or outmost turns usually.If make bias power Pb identical, also can write down bias power Pb under the situation about then having with playback power P r.So-called groove distortion is groove crawl (swing) etc. specifically.
Perhaps, utilizing the distortion of pre-pit string or groove address information to be recorded in advance on the optic informating recording medium on the substrate, also can be with this address information, in this address, comprise suitable and α 1And α iRelevant information.
By means of this, can be when access with read address information and also read this pulse dividing method information simultaneously, can the switch pulse dividing method, can also not carry out special indemnities, just select to be fit to the pulse dividing method of this recording medium and this address affiliated area.
Above-mentioned like that for each zone while change the recording impulse partitioning scheme, in the mode that whole disc writes down, also can adopt ZCLV mode (zone C LV).The following describes object lesson.
If recording areas is divided into a plurality of zones along radial direction, in each zone, carry out record with certain linear velocity,
Is 1.2~2 at the line speed record Vin of inner circle area with ratio Vout/Vin at the line speed record Vout in outmost turns zone,
If α i=0.3~0.6 (2≤i≤m) and β m=0~1.5,
If α i+ β I-1(3≤i≤m), α iT, Pe/Pw and Pb and linear velocity are irrelevant, are certain value, and make α i(2≤i≤m) and/or β m change according to linear velocity, carry out record with this.
The ZCLV mode is divided into a plurality of zones with recording areas on radial direction, this point is identical with the ZCAV mode, but be according to the CLV mode in the same area, be that linear velocity is certain, while disc is rotated and carry out record.
Therefore, when recording method of the present invention was used for the ZCLV mode, the linear velocity of establishing inner circle area and outmost turns zone was respectively Vin and Vout, at this moment by reducing the poor of Vin and Vout, for example making Vout/Vin is 1.2~2, to reduce the compliance of medium to linear velocity.
Medium of the present invention only change the recording impulse dividing method a little, just can carry out record in the wide range of on-line velocity 3~8m/s, therefore can adopt the ZCLV mode that is divided into less number of regions.
At this moment, for become with the zone irrelevant etc. recording density, make the Tq<Vq of the record data reference clock signal period T q in each regional linear velocity Vq and each zone〉ave and q irrespectively keep certain value.
Then, in each zone, adopt best titime pulse dividing method.That is to say that (m, α are established in 2≤i≤m) and β m=0~1.5 to establish α i=0.3~0.5 i+ β I-1(3≤i≤m), α iT, Pe/Pw and Pb and linear velocity are irrelevant, are certain value, make α according to linear velocity iAnd/or β mVariation is to carry out record.
In aforesaid CLV mode, ZCAV mode or ZCLV mode, the example that changes the recording impulse dividing method according to the linear velocity of playback time mainly is to make β m for simplifying the method for pulse generating circuit with the irrelevant certain value of linear velocity.Otherwise, also still possible to seek simplifying pulse generating circuit by positive change β m.
That is to say and adopt following optic recording method, promptly crystalline substance is being tied polymorphic segment as record, erase status, and with amorphous portion as recording status, utilizing the shortest spot length is multiple record spot length below the 0.5 μ m when coming recorded information,
Irradiation can make the recording light of the erase power Pe of amorphous state crystallization between the record spot,
When 1 record spot time span is nT (T is the reference clock signal cycle, and n is the integer more than 2),
To write down spot time span nT and cut apart in proper order, promptly according to this
η 1T、α 1T、β 1T、α 2T、β 2T、……、
α iT、β iT……αmT、βmT、η 2T
(in the formula, m is that number is cut apart in pulse, and m=n-k, k are the integer of 0≤k≤2.
Establish ∑ again, ii+ β i)+η 1+ η 2=n, η 1 is the real number of η 1 〉=0, η 2 is the real number of η 2 〉=0,0≤η 1+ η 2≤2.0,
If α i(1≤i≤m) is α i0 real number, β i(1≤i≤m) is β i0 real number,
If α i=0.1~1.5, β i=0.5~1.0, β m=0~1.5, in the i of 2≤i≤m, α i is in 0.1~0.8 scope, and is and irrelevant with i, is certain value.
Again, in the i of 3≤i≤m, α i+ β I-1In 0.5~1.5 scope, and irrelevant with i, be certain value.
At α iT (in the time of 1≤i≤m), irradiation is enough to make the Pw of recording layer fusion〉recording light of the recording power Pw of Pe, at β iT (in the time of 1≤i≤m), the recording light of the bias power Pb of irradiation 0<Pb≤0.2Pe (wherein, the relation of 0<Pb≤Pe can be arranged in β mT),
If m, α i+ β I-1(3≤i≤m), α iT and α i(2≤i≤m) irrelevant with linear velocity be certain value, and linear velocity is more little, and the dull ground that increases of β m is changed for T.
At first,, adopt above-mentioned ZCAV mode or ZCLV mode, make the variation that is inversely proportional to of reference clock signal period T and linear velocity for the density of holding the record is certain.
Then, in 3≤i≤m, be preferably among 2≤i≤m at least, establish α i+ β I-1Irrelevant with linear velocity and i, be certain value, pulse generating circuit can be simplified like this, and α can be made iDull deceleration is little with the linear velocity reduction, and the recording layer cooling velocity is increased.Usually establish α i+ β I-1=1.0.
In order to realize such pulse dividing method, as long as in the gate signal generation sequential key diagram of Figure 11, producing 1 width with reference clock signal period T synchronous (can add certain delay) is α iFixed width pulse (Gate1) and a plurality of follow-up width of T are α iThe fixed width pulse (Gate2) of T (α cT) on the other hand, only makes the Gate3 of decision final cutting pulse width β mT get final product according to change of line speed.
Here, the dominant record power in each line speed record is designated as Pwmax, and smallest record power is designated as Pwmin, at this moment preferably sets
Pwmax/Pwmin≤1.2,
Pe/Pw=0.4~0.6,
0≤Pb≤1.5(mW)。
Again, as previously mentioned, the linear velocity when rewriteeing at least is 5m/s when following, and the fire damage in order to prevent to rewrite repeatedly in m=n-1, is preferably established ∑ α i<0.4n; In m=n-2, preferably establish ∑ α i<0.5n.
Moreover establishing when rewriteeing at the β of maximum linear velocity m is β HM, the β m of minimum rate of accumulation speed is β LM, then can adopt the β m that gets each linear velocity when rewriteeing is β HM and β LValue between the m, and Pb and Pe/Pw than for the recording method of the irrelevant certain value of line speed record.
In this case, if Pe/Pw ratio, Pb, Pw, α at least 1T, α iT, (β LM and β HM) numerical value utilizes pre-pit string or groove distortion to be recorded on the substrate of medium in advance, then can select the optimum pulse dividing method automatically equally, and this is more satisfactory.
Also have, if maximum line velocity reaches about one times of minimum line speed, then also can realize keeping the signal quality of enough practicalities, β m be the optic recording method of the certain value that has nothing to do with line speed record simultaneously.
In the formula of singly the putting DVD of CLV mode driver, have a kind of mode be with the reference clock signal cycle that the playback spot obtains be benchmark, produce data clock signal and rotary synchronous signal, be rotated control.
As mentioned above, be and the irrelevant approximate certain value of record radius to adopt the ZCAV mode to write down the formula of singly putting DVD driver that the medium of spot can enough the manner and directly reset and need not change as the shortest spot length or channel bit length.
That is to say, owing to can utilize PLL (Phase Lock Loop, being phaselocked loop) mode is rotated synchro control, and make the reference clock signal period T q ' of the data that generate by the record spot roughly consistent with the Tr of the reference data clock signal of this driver, even therefore how many linear velocity or channel bit length have some variation, playback circuitry also can intactly directly be decoded.
Particularly the shortest spot length is 0.4 μ m and is roughly the EFM enhancement mode modulating data that writes down definitely in All Ranges, and according to the rotary synchronous signal that the spot by record generates, it is synchronous to reach the CLV rotation that utilizes PLL control.Producing frequency simultaneously is the reference data clock signal Tr of 25~27MHz scope, according to this clock, can not recognize interregional transfer, and reset as CLV recording medium.
Certainly, be issued to rotation synchronously, then can carry out the playback of 2 times of speed as if the situation that at the reference data clock is Tr/2.The rotary synchronous signal generation circuit that utilizes the PLL mode like this can intactly use the mode of known DVD player or DVD-ROM driver.
Medium of the present invention can be guaranteed in the whole characteristics of signals except that reflectivity the playback interchangeability with DVD.Therefore, it is desirable to record in the groove, perhaps preferably the push-pull signal of groove is little.This is that then the tracking servo signal of the DPD method of playback time use is little because if the push-pull signal of groove is big.Thereby groove depth must be maximum λ/(8n) shallow than push-pull signal.In the formula, λ is airborne playback light wavelength, and n is the refractive index of substrate.But common tracking servo will utilize push-pull signal during owing to record, and is therefore too small also bad.
Again, about the replay signal characteristic, in order to obtain high CN ratio, preferably degree of modulation Mod is more than 0.5.Here establishing Mod is (amplitude of DC replay signal envelope)/(the last end value of DC replay signal envelope).
Desirable groove depth is d=λ/(20n)~λ/(10n).If than λ/(20n) also shallow, the push-pull signal when then writing down is too small, does not carry out tracking servo; If darker than λ/(10n), the tracking servo instability of playback time then.For example, at the record reproducing wavelength be about 630~670nm, numerical aperture of objective NA is that groove depth is preferably in 25~40nm scope under 0.6~0.65 the situation.
Again, in order to ensure with DVD the capacity of identical size being arranged, separation is got 0.6~0.8 μ m, if separation is 0.74 μ m, then easily and DVD interchangeability is arranged.
Groove width is 0.25~0.5 μ m preferably.If narrower than 0.25 μ m, then push-pull signal is too small; If wideer than 0.5 μ m, narrowed width between groove then, resin is difficult to enter during the substrate reaction-injection moulding, and the shape of groove is difficult to correctly copy on the substrate.
Medium of the present invention reduce in record back reflection rate.In such medium, reduce in order to make the reflectivity in the groove, that is to say that if the average reflectance in the record pit is designated as RGa, the average reflectance between the record pit is designated as RLa, then in order to make RGa<RLa, preferably groove width is narrower than width between groove.
For example, in order to obtain the interchangeability with DVD, if establishing separation is 0.74 μ m, then groove width cans be compared to one half most, promptly 0.37 μ m is narrow.
On the other hand, if the average reflectance before the record in the groove is designated as RGb, average reflectance before the record between groove is designated as RLb, as long as satisfying above-mentioned RGa<RLa, also can be RGb〉under the situation of RLb, groove width is made as 0.4~0.5 μ m, can add the wide point of the amorphous state spot that writes down in the sipes with this, improve degree of modulation, or reduce and beat.
In order to visit Unrecorded particular lane, make the synchronizing signal of substrate in order to obtain again with certain linear velocity rotation, at these grooves periodically deforming is set sometimes.Usually many is the swing (wobble) of crawling in the transverse direction formation in road, that is to say, if groove crawls with certain frequency fwo, then by detecting its frequency, just can utilize the PLL mode to take out the signal of the synchronous usefulness of rotation.
The amplitude that groove crawls is preferably 40~80nm (peak value is to peak value).If less than 40nm, then amplitude is too small, and signal noise (SN) is than degenerating; If surpass 80nm, the upper and lower side of the envelope of tracer signal then shown in Figure 6 comprises the too much low frequency component by the swinging signal generation, and it is big that the replay signal distortion becomes.
Under the situation of hunting frequency near the record data frequency band, preferably its amplitude is below the 80nm.
Moreover, if with this frequency f wo that crawls as carrier wave, according to specific address information, form crawling of frequency modulation (PFM) or phase modulation (PM), then its playback can be obtained address information.
If to make the frequency f wo that crawls is that certain value forms the groove that crawls, then, also can produce the reference clock signal T that data are used according to the groove that generates by fwo crawl reference period Tw or its multiple or the approximate number of signal.
Usually, be set at low frequency or the sufficiently high high frequency enough lower hunting period, mix with the data-signal component preventing, easily separately with bandpass filter etc. than data frequency components.Particularly under the situation of fwo about than low 1~2 order of magnitude of data base clock signal period, also can practicability even can write CD etc.
In the medium that adopt the CLV mode, after reaching PLL rotation synchronously, the multiple with about 1~2 order of magnitude of fwo raising generates the data base clock signal.The data base clock signal that adopts this method to generate is rotated synchronous swing usually and is influenced (fwo about 0.1~1%), therefore is attended by the swing with data base clock signal (frequency) same order easily.This makes the window surplus deterioration that Data Detection is used.
Therefore, different with the groove signal that crawls, for the swing of offset data reference clock signal, insert pre-pit or the big special swing of amplitude also is effective every certain data length.On the other hand, if fwo is in data base clock signal frequency (1/T) or its 1/100 to 100 times the scope, then reach rotation synchronously after, with the swinging signal of obtaining is benchmark, even constant same as before generation data base clock signal also can be guaranteed enough precision, that is to say, establish
100/T≥fwo≥1/(100T) (5)
Again, in the ZCAV method of having narrated, the reference clock signal period T q that preferably makes generation is each regional groove crawl multiple or the approximate number of reference period Twq.That is to say that each area change frequency f wo simultaneously forms groove with a fixed angular speed and crawls, can produce the reference clock signal that generates as fwo or its frequency that increases progressively multiple like this as data reference clock signal Tq.
At this moment, if the swing that makes groove then generates each regional data base clock signal easily for satisfying the upper frequency of (5) formula.Can change each regional reference clock signal Tq like this, can produce the variable pulse dividing method with this signal Synchronization, can reduce each pulse position precision or swing of cutting apart, be more satisfactory.
As one of the Region Segmentation of ZCAV mode example, can consider that a circle with groove is as 1 zone.At this moment it is certain swing that groove has the cycle that has nothing to do with the zone.
If separation is TP, the cycle of crawling is Tw 0If, be similar to and satisfy following relational expression,
2π·TP=a·Tw 0·V 0
(in the formula, a is a natural number)
Then form period T w in whole recording areas 0Be certain swing, only the every formation of one of recording channel circle outer ring increases a swing.
And, Tw 0To be the integral multiple of reference clock signal period T, i.e. Tw 0=mT (m is a natural number), this is according to Tw 0When producing reference clock, as long as be 1 of integer branch merely, therefore can simplify reference clock generation circuit, this is desirable.In this case, m also can be similar to and not be natural number, can allow ± about 5% error.
That is to say, for TP=0.74 μ m, if establish V 0=3.5m/s, T=38.23nsec, n=1, then m ≈ 34.7, are approximately Tw hunting period if establish 0=35T, the contained swing number of then per 1 circle increases by 1.
Advantage in this case is to adopt the CLV mode, although introduced swing, because the swaying phase of phase neighboring trace is always consistent, therefore owing to the playback oscillation amplitude change of the swinging signal of interfering (beat) to cause is less.
Suitable example of the present invention more than has been described, but the present invention is effectively for the general spot length records of phase change media improving linear velocity compliance and recording power compliance, is not limited to erasable DVD.
For example, be the blue laser of 350~500nm and when to use optical system more than the NA=0.6 to carry out the shortest spot length be spot length modulated record below the 0.3 μ m adopting wavelength, medium of the present invention and recording method also are effective.The shortest spot length is if consider the stability of spot, be preferably about 10nm more than.
At this moment the Temperature Distribution that must be noted that the transverse direction that makes is mild, and 5~15nm that the 2nd protection tunic is made as thin as a wafer is effective.
When adopting wavelength to be the laser of 350~450nm, 10nm is following even more ideal.
Moreover medium of the present invention also go for both write down, are so-called piston ring land and groove record as recording channel between groove and groove.Must satisfy the identical recordings characteristic with piston ring land and groove, certain difficulty is arranged, but, be suitable for high density recording easily keeping dwindling track pitch under the constant situation of groove width broad.Width LW is 0.2~0.4 μ m between groove width GW and groove by making, and can realize high density, can access stable tracking servo performance simultaneously.And, can keep then reaching in the groove that both have identical signal quality between groove if the GW/LW ratio is 0.8 or more below 1.2.In order to reduce crosstalk influence, preferably establish groove depth d=λ/(7n)~λ/(5n) or λ/(3.5n)~λ/(2.5n).
Embodiment
Below described be embodiment, as long as the present invention is no more than its main points, be not limited to the following examples.
In the following embodiments, substrate is made by injection molding.Substrate is the polycarbonate resin substrate of the injection molding of thickness 0.6mm, only otherwise explanation especially in advance, adopts the substrate of the spiral slot that forms separation 0.74 μ m, wide 0.34 μ m, dark 30nm.
Only otherwise explanation especially in advance has the swing that frequency is 140KHz during groove on-line velocity 3.5m/s, wobble amplitude is about 60nm (peak value is to peak value).
Also have, the shape of groove adopts the approximate optical diffraction method of U groove to measure.Also can carry out example to the shape of groove with scanning electron microscope or scanning electron microprobe microscope.At this moment, groove width adopts the width of half position of groove depth.
Only otherwise explanation especially in advance, on this substrate with 4 layers of structure film forming shown in Fig. 5 (a) after, utilize spin coating method that the protective seam that ultraviolet hardening resin constitutes is set thereon, have the thick substrate of the 0.6mm of identical layer structure with another sheet again and paste mutually.And among below the embodiment and comparative example, first protective seam among Fig. 5 (a) is called the bottom protective seam, the 2nd protective seam is called upper protective layer.
Just the recording layer after the film forming is an amorphous state, the wavelength that utilization is focused to the about 90 μ m of major axis, the about 1.3 μ m of minor axis is the laser beam of 810~830nm, it is the laser of 500~700mW that on-line velocity is selected suitable linear velocity irradiation initialization power in 3.0 to the 6.0m/s scopes, makes its whole fusion, recrystallizes the back as initial (record) state.
Each layer composition utilizes method synthesis such as fluorescent x-ary analysis, atomic absorption spectroscopy and excitation of X-rays photoelectron spectrum analysis method to confirm.
The film density of recording layer and the protective seam weight change when forming the thick film in hundreds of nm left and right sides on substrate is tried to achieve.The thickness that the thickness utilization is obtained by contact pilotage measuring instrument measurement fluorescent X-ray intensity is proofreaied and correct the back and is used.
The area resistivity in reflection horizon utilizes 4 balancing point method resistance measuring instruments { Loresta FP (trade name), Mitsubishi's oiling (now being Dia Instrument) society's system } to measure.
Resistance measurement is to measure with the reflection horizon of film forming on the glass of insulation or the polycarbonate resin substrate or with the reflection horizon as the superiors after 4 layers of structure (the ultraviolet hardening resin protection covers preceding) film forming of Fig. 5.
Because upper protective layer is the insulator of thin dielectric film, even therefore 4 layers of structure are measured also not influence to the area resistivity in reflection horizon.In addition, measure according in fact regarding unlimited large-area diameter 120mm disc substrates shape as.
According to resulting resistance value R, utilize following formula reference area electricalresistivity s and specific insulation ρ v.
ρs=F·R      (6)
ρv=ρs·t      (7)
In the formula, t is a thickness, and the serve as reasons correction factor of the film region shape decision of measuring of F gets 4.3~4.5.Here get 4.4.
Only otherwise explanation especially in advance, the DDU1000 evaluating apparatus that adopts Pulse Tech company to produce carries out the record reproducing evaluation.The wavelength of laser head is 637 μ m, and numerical aperture of objective NA is 0.6 or 0.63.Beam diameter is respectively about 0.90 μ m and about 0.87 μ m.Also have, the energy intensity that beam diameter is equivalent to Gaussian beam is the 1/e of peak strength 2Above zone.
Record is to adopt pulse dividing method shown in Figure 10, only otherwise explanation is especially in advance established m=n-1, α i+ β I-1=1.0 (2≤i≤m), Pb is the 1.0mW identical with playback power under institute's wire speed situation, is certain value.Only otherwise explanation especially in advance, Pe/Pw is 0.5, is certain value, establishes Pb and be the certain value between 0.8~1.0mW, changes Pw, measures degree of modulation and beats.
The signal of record is the random signal of 8~16 modulation (modulation of EFM enhancement mode) of DVD employing.Only otherwise explanation especially in advance, establishing the shortest spot length is 0.4 μ m.Again, under situation about not illustrating especially in advance, be under the state that only writes down, to measure with single recording channel, therefore do not comprise the crosstalk influence.
Record is that the standard lines speed 3.5m/s with DVD is 1 times of speed, carries out with 1 times of speed, 2 times of various linear velocities such as speed,
Reset and always to carry out with linear velocity 3.5m/s, beating is with by measuring after 2 values of the replay signal behind the balanced device.Be meant beat (the adge-to clock jitter) of border to clock and beat, measured value is used with respect to the percentage of reference clock signal period T (%) and is represented, the characteristic of balanced device is according to the standard of read-only DVD.Preferably can access with respect to reference clock signal period T=38.2nsec (26.16MHz) to less than the beating and 50% above degree of modulation of about 10% (better is less than 8%), better is degree of modulation more than 60%.Also have, beating after wishing to rewrite repeatedly increases smaller, and after at least 100 times, best 1000 later beating can maintain less than 13% with respect to T.
In addition, from guaranteeing the position with the interchangeability of read-only DVD, the important point is to measure with the playback light of 650~660nm, but can confirm that medium wavelength of the present invention only produces faint influence to the focused beam shape, if adjust the playback optical system, also can access identical the beating of using with the present invention of 637nm optical system with the 660nm optical system.
(embodiment 1 and comparative example 1)
For relatively as the InGeSbTe of the present invention system of recording layer with one to well-known InAgSbTe quaternary system, shown in table-1, prepared to remove Ag form with Ge, recording layer composition and a layer structure almost be the medium of strict conformance.
Two recording layers are except Ge and the Ag displacement, and other are formed and nearly all can regard as in the measuring error scope is in very identical scope.The thickness of bottom protective seam is not both in order to adjust to such an extent that make the reflectivity Rtop of medium identical.Since the reflectivity of recording layer have a little not with, therefore must carry out such correction, but for the efficiency of light absorption that makes recording layer is identical, compare after making the influence of the fire damage that produces by playback light identical, just must revise.Because recording layer thickness and upper protective layer thickness are identical, so radiating effect and fire damage can regard identical as.
Substrate is the thick polycarbonate resin of 0.6mm, forms the groove of separation 0.74 μ m, groove width 0.34 μ m, groove depth 27nm, hunting frequency 140KHz (linear velocity 3.5m/s), wobble amplitude 60nm (peak value is to peak value), carries out record in this groove.
To these two kinds of medium, carry out record with line speed record 3.5m/s, T=38.2nsec, the modulation of EFM enhancement mode, demonstrate good regenerative recording characteristic.The regenerative recording condition may not be that the characteristic of each disc is best condition, but carries out with both sides' characteristic roughly the same common conditions shown in table-1.
That is to say, in the pulse dividing method shown in Figure 10 (a), establish m=n-1, α i+ β I-1=1.0 (2≤i≤m), α i=α c=certain value (2≤i≤m), α i=0.5, α c=0.3, β m=0.5 establishes Pw=13.5mW again, Pe=6.5mW, Pb=0.8mW.
Signal to such record shines playback light repeatedly, the stability of research playback light.Behind the playback luminous power Pr irradiation stipulated number with regulation, the playback luminous power is reduced to enough low 0.5mW, measurement such as beat.The results are shown among Figure 12.
The medium of embodiment 1 are under the situation of 1mW until 10 in the playback luminous power 6Inferior the deterioration that playback light causes do not appear fully, the every increase of power 0.1mW, and deterioration is accelerated gradually.
The medium of, comparative example 1 are under all the playback light situations more than the playback luminous power 1mW on the other hand, the interval till initial 100~1000 times, beating sharply increases, deterioration slowly then, as a whole, the jitter values height, but the initial deterioration of beating is fatal.
In comparative example 1, also have, descend, shine about 100 times and will descend about 10% owing to playback light makes degree of modulation.Can think, initial owing to the sharply increase of beating, so the decline of degree of modulation is carried out inhomogeneously.
The medium of finishing that write down of embodiment 1 and comparative example 1 are placed on the accelerated test of carrying out under the 80 ℃/80%RH environment.The disc characteristic of embodiment 1 does not change basically fully after 250 hours, and opposite, the tracer signal of the disc of comparative example 1 almost completely disappears.As can be known, the amorphous state spot is extremely unstable in the recording layer material of the composition of comparative example 1.
Like this, in the disc of embodiment 1, the stability of initial regenerative recording characteristic, the light of anti-playback the and long-time stability are all fine.This expression is for Sb 0.7Te 0.3In contain the alloy system of superfluous Sb, it is very resultful adding suitable Ge.
About embodiment 1 medium, under the environment of 80 ℃/80%RH, carried out being accelerated into test, implemented to reach 2000 hours accelerated test.The signal of record before the accelerated test, the degree of its deterioration of beating only about 1%.
Again, degree of modulation is 64% in the early stage, and also has 61% at 2000 hours after the accelerated test, does not almost change.Reflectivity does not almost completely change yet.When after 2000 hours non-recorded part being write down for the first time, the deterioration of beating is about 3%, is fully no problem in practicality.
Again, studied in great detail in embodiment 1 medium, relation with the recording impulse dividing method is to beat under the situation of m=n-1 and m=n-2.
Figure 13 when being illustrated in linear velocity and being 3.5m/s respectively by (a) m=n-1, beating and α when (b) m=n-2 writes down iAnd the contour map of the relation of α c.
Again, Figure 14 when being illustrated in linear velocity and being 7.0m/s respectively by (a) m=n-1, beating and α when (b) m=n-2 writes down iAnd the contour map of the relation of α c.Each figure measures used Pw, Pe, Pb and β m and is shown on each figure.
As can be seen, under the situation of on-line velocity 3.5m/s, under any situation of m=n-1 and m=n-2 at α i=0.7~0.8, can both obtain minimum beating (about below 7%) near α c=0.35~0.40.
Again as can be seen, under the situation of on-line velocity 7.0m/s, under any situation of m=n-1 and m=n-2 at α iCan both obtain minimum beating near=0.5 and near the α c=0.4.For obtaining near the minimum α that beats iAnd α c, either way satisfy ∑ α iThe condition of<0.5n.
In addition, in the present embodiment, under any situation of on-line velocity 3.5m/s and 7.0m/s, get m=n-2 and can both obtain lower jitter values, and compare, with respect to bigger α with the situation of m=n-1 iAlso can access low beating.
Further with the medium of the foregoing description 1,, shown in table-2, change the recording impulse dividing method to beating and the relation of linear velocity is estimated with the evaluating apparatus of NA=0.63.Reference clock signal period T and linear velocity are inversely proportional to.The pulse dividing method is to establish m=n-1, α i+ β I-1(2≤i≤m), α i=α c=certain value (2≤i≤m).If Pw, Pb and Pe and linear velocity are irrelevant, be certain value.Here in the pulse dividing method of table-2, all satisfy ∑ α for institute's wire speed iThe relation of<0.5n.
From about 1 times of speed to 2.5 times speed of dvd standard linear velocity, can access good rewriting characteristic.These medium are that recording areas is divided into 3~4 zones, and each zone is only changed the recording impulse strategy a little, like this, even the CAV mode also demonstrates good rewriting characteristic in whole recording areas.
Again, carry out recording playback, also obtained same result with the evaluating apparatus of wavelength 660nm, NA=0.65.
(embodiment 2)
The bottom protective seam (ZnS) of various thickness is set on substrate 80(SiO 2) 20, recording layer Ge 0.05Sb 0.73Te 0.22, upper protective layer (ZnS) 80(SiO 2) 20And reflection horizon Al 0.995Ta 0.005With the thick table 3 that is shown in of each tunic.All films all are to utilize sputtering method to make under the condition that does not break away from vacuum.
The reflection horizon film forming is to reach 2 * 10 in vacuum tightness -4Pa is following, carry out under the condition of Ar pressure 0.54Pa, film forming speed 1.3nm/ second.
Its specific insulation is 55n Ω m, and area resistivity is 0.28 Ω/.
Impurity such as oxygen, nitrogen can be thought the barely 1 atom % that all adds up below the detection sensitivity with the beam split of x-ray excitation photoelectron.(ZnS) 80(SiO 2) 20The film density of protective seam is 3.50g/cm 3, be theoretical bulk density 3.72 gram/cm 394%.Again, recording layer density is 90% of bulk density (bulk).The protective seam pyroconductivity of estimating according to thermal simulation is 3.5 * 10 -4PJ/ (μ mKnsec).
To the medium made like this respectively under 1 times of speed and 2 times of speed, to each Media layer structure with the pulse dividing method optimization shown in Figure 10 (a), then write down (rewriting) with it.Then, measure beating after rewriteeing for the 1st time, 10 times, 1000 times, all adopt the optical system of wavelength 637nm, NA=0.63 during measurement for record, playback.
Table gathered in-3 each medium 1 times when fast the optimum pulse dividing method, beat, Rtop and degree of modulation.
All be to carry out the spot length modulated record that the shortest spot length is 0.4 μ m under all situations, obtain bigger initial modulation degree with 1 times of speed.
If establishing the upper protective layer thickness is 20nm, beating after then initially beating, rewriteeing for 1000 times all less than 10%.If establishing the upper protective layer thickness is 30nm, it is good then initially to beat, but making beats slightly increases because of rewriteeing repeatedly, and after 1000 rewritings, beating reaches 10~12%.If establishing the upper protective layer thickness is 40nm, then initially beating reaches more than 13%, and because of rewriteeing sharply deterioration repeatedly, reaches more than 20%.
Also has the thick embodiment 2 (h2) that reaches 30nm of recording layer thickness.It is more than 13% that its first platform record is beated, and the deterioration of beating that causes is remarkable owing to rewriteeing repeatedly.
Bottom protective seam thickness is the embodiment 2 (i2) of 45nm, and it rewrites poor durability repeatedly.
Again, thickness is the reflection horizon of 250nm, can access littler beating than 200nm.That is to say that it is more satisfactory in highdensity like this spot length records, adopting " super chilling structure ".
Estimate the relation with recording power Pw of beating of embodiment 2 (g1) medium below.The pulse dividing method is the m=n-1 among Figure 10, establishes Pw=14mW, Pe/Pw=0.5, β m=0.5, carries out record with 1 times of speed and 2 times of speed.Thereafter, evaluation is beated with respect to α iAnd α c=α i(the relation of 2≤i≤m).
At 2 times when fast, establish α i=0.5, α c=0.4, β m=β N-1=0.5, Pw=14mW; At 1 times when fast, establish α i=0.7, α c=0.3, β m=β N-1=0.5, Pw=14mW.At this moment, at 2 times when fast, ∑ α i=0.3n (n=3), 0.33n (n=4), 0.34n (n=5), 0.38n following (n=6~14).At 1 times when fast, ∑ α i=0.33n (n=3), 0.33n=(n=4), 0.32n (n=5), 0.32n following (n=6~14).
It is the results are shown in Figure 15, beating and the relation of recording power Pw and the relation that rewrites back reflection rate Rtop and degree of modulation Mod and recording power Pw 10 times after having provided the 1st time and 10 times and rewriteeing.(a) being the situation of 2 times of speed recordings, (b) is the situation of 1 times of speed recording., then Rtop is equivalent to the Itop of Fig. 6.So-called DOW (DirectOverwrite) refers to rewriting among the figure.
Estimate below and rewrite permanance.Figure 16 shows that its result.Represent respectively after rewriteeing for 1000 times, to beat, the value of reflectivity and degree of modulation.(a) being the situation of 2 times of speed recordings, (b) is the situation of 1 times of speed recording.Any situation all is to increase gradually beating before rewrite about 10 times, and just settles out later on for 10 times, beats, degree of modulation and reflectivity be not until all almost have deterioration 1000 times.
Moreover, to these medium except with linear velocity 9m/s, to establish the reference clock signal cycle be the 14.9nsec, adopts the pulse dividing method identical with above-mentioned 2 times of speed (linear velocity 7m/s), rewrite with Pw=14mW.Wipe than the above enough numerical value that obtains 30dB.And beating also is good result less than 11%.
For embodiment 2 (g1) medium, in on-line velocity 3~8m/s scope, establish Pw=14mW, Pb=1mW, Pe/Pw=0.5, β m=0.5 is certain value, by only changing α iAnd α c, can access less beating.That is to say, during with linear velocity 3~5m/s, α i=0.7, α c=0.35; And during with linear velocity 5~7m/s, α i=0.65, α c=0.4; During with linear velocity 7~8m/s, α i=0.55, if α c=0.45 so at least to divide three sections variations, then can access approximately less the beating less than 9%.If more segmentation changes α at interval with 1m/s iAnd α c, then can think can both obtain littler beating in each linear velocity.
Again, when Pw=11~14mW, Pe/Pw 0.4~0.5 can access minimum beating.And if Pb surpasses 1.5mW, the rapid deterioration of then beating is when studying Pe/Pw=0.5 and the relation of Pb here, if Pb less than 1.0mW, then can access near minimum beating.That is Pb/Pe must be less than 0.2.
Relatively the upper protective layer thickness is the embodiment 2 (g1) of 20nm and the embodiment 2 (d2) of 40nm below.To 1 times of two medium measurement as described below when fast with the relation of record spot length.
Adopt the optical system of NA=0.6, in the modulation of EFM enhancement mode, will estimate the relation of beating this moment as the 3T spot length of the shortest spot from 0.5 μ m shortening with spot length.Line speed record is the certain value of 3.5m/s, and the pulse dividing method also adopts said method, adopts certain value, changes the reference clock signal cycle to change in the spot length.Here, when the shortest spot length is 0.46 μ m when above, because the restriction on the device is carried out difficulty of CLV control ratio at playback speed 3.5m/s, therefore establishing playback speed is 5m/s.In addition, the shortest spot length is 0.4 μ m, and is corresponding with read-only dvd standard.
It is the results are shown among Figure 17, (a) is the medium of embodiment 2 (g1), (b) is the medium of embodiment 2 (d2).
As seen from the figure, the medium of embodiment 2 (g1), its shortest spot length is beated less than 13% to about the 0.38 μ m, can use.
In addition, if adopt the optical system of NA=0.63, then can reduce about about 2% beat.If make the balanced device optimization of playback time, then still can reduce about 2%.If add the optical system of using NA=0.65.Even then be that 0.35 μ m also can think and can access enough little beating.
The medium of embodiment 2 (d2) are 0.45 μ m when above in spot length, can access no problem basically beating, and sharply increase but then beat less than 0.45 μ m, and when spot length was 0.40 μ m, beating was more than 13%, can not use.
Below, in order to carry out the evaluation of so-called tilt margins, behind the random pattern signal that record EFM enhancement mode is modulated in continuous many recording channels on to the medium of embodiment 2 (g1), substrate is tilted with respect to the playback laser beam axis, measure the variation of beating of playback time.The optical system NA=0.6 of recording playback, line speed record are 1 times of speed or 2 times of speed, and any situation all is to reset after 10 rewritings.Measurement result is shown among Figure 18.Tilt margins is ± 0.5~0.6 degree radially being ± 0.7~0.8 degree at circumferencial direction, and in common driver, such size is no problem.
<accelerated test 〉
To the part of records road of embodiment 2 (g1) medium, adopt above-mentioned optimum pulse dividing method, with the random pattern (pattern) of Pw=13mW record EFM enhancement mode modulation, measurement is beated.Then, these medium are carried out accelerated test under 80 °/80RH hot and humid, after 500 hours and after 1000 hours, measure beating of this recording channel once more, deterioration about 1% only after 1000 hours in accelerated test.
Again, after 1000 hours, with above-mentioned the same terms record random pattern, measurement is beated, and finds deterioration about 2%, and is no problem in this degree practicality to other recording channels in accelerated test.
Carry out record equally with 1 times of speed and 2 times of speed again, estimate the degree of modulation of the hot and humid following 1000 hours accelerated tests front and back of 80 °/80RH.1 times when fast, the initial modulation degree is 61%, and degree of modulation is 58% after the accelerated test.2 times when fast, the initial modulation degree is 60%, and degree of modulation is 58% after the accelerated test.
The stability that<counterweight is given out light 〉
To embodiment 2 (g1) medium, power is increased to 1.2mW irradiation playback light, there is not deterioration about 10 minutes fully.Then, making power is 1.0mW, shines playback light to 100 repeatedly ten thousand times, and the increase of beating is less than 2%.
(embodiment 3)
Except recording layer is formed employing Ge 0.05Sb 0.71Te 0.24In addition, adopt the layer structure identical with embodiment 2, make medium, each tunic layer and evaluation result are shown in table-4.Use the optical system of NA=0.63 to measure.
Identical with table-3, various layer structure are got best α i, α c and β N-1, be minimum Pw and Pe but also set can make to beat, estimate beating.
For embodiment 3 (a), the same with embodiment 2 (a1), line speed record is that 1 times of speed and 2 times can access good characteristic when fast, but when 9m/s, it is higher by 1~2% than embodiment 2 (a1) to beat.
Again, be the embodiment 3 (a)~(f) of 30nm for upper strata protective seam thickness, can access beats rewrite less than 10%, 100 time after also less than 13%.For the upper protective layer thickness is the thicker embodiment 3 (g)~(i) of 40nm, and value greater than 13% can only obtain beating.
(embodiment 4)
Layer structure is bottom protective seam (ZnS) 80(SiO 2) 20Thickness is 215nm, recording layer Ge 0.05Sb 0.69Te 0.26Thickness is 18nm, upper protective layer (ZnS) 80(SiO 2) 20Thickness is 18nm, reflection horizon Al 0.995Ta 0.005Thickness is 200nm.This recording layer composition writes down with linear velocity 3~5m/s and can access good characteristic, is so-called 1 times of speed recording layer.But, therefore steady in a long-term good because superfluous Sb amount is more a little bit smaller a little than embodiment 2 and 3, for the storage stability of paying attention to recorded information and the deterioration that causes owing to resetting repeatedly, promptly the reset situation of light permanance is more satisfactory.
Estimate with the optical system of NA=0.6 below.The decision as described below of optimum pulse dividing method.When line speed record is 3.5m/s, establish Pw=13mW, Pe/Pw=0.05, the β m=0.5 in Figure 10 is certain value, and changes α iWith α c to obtain minimum beating, select such pulse dividing method.Beating and α after representing to rewrite for 10 times with the contour map of beating among Figure 19 iAnd the relation of α c.Owing to establish α i=0.4~0.8, to access be best beating basically in α c=0.3~0.35, therefore based on this, selects α i=0.6, α c=0.35.At this moment, ∑ α i=0.32n (n=3), 0.33n (n=4), 0.3n (n=5) or less than 0.35n (n=6~14).
Degree of modulation is 65%, and is also not a halfpenny the worse even this numerical value is compared with read-only DVD.Rtop is about 23%, if in fact more than 15%, can think and promptly use the existing driver of singly putting also can reset.
Therefore, recording medium of the present invention with Pw=12.5mW, linear velocity 3.5m/s recording image data, is attempted resetting with the read-only DVD player of selling, then focus servo signal, tracking servo signal and beat and to access identical characteristic with common read-only DVD.
<rewrite permanance repeatedly 〉
Beat when Figure 20 shows that Pw=12.5mW, Rtop and degree of modulation and the relation of number of rewrites repeatedly.After rewriteeing more than 1000 times, still show sufficiently stable characteristic.
<accelerated test 〉
To the part of records road of these medium, adopt above-mentioned optimum pulse dividing method, with the random pattern of Pw=13mW record EFM enhancement mode modulation, measurement is beated.Then, these medium are carried out accelerated test under 80 ℃/80%RH hot and humid.After 500 hours and after 1000 hours, measure beating of this recording channel in accelerated test once more, the deterioration less than 0.5% was only arranged after 1000 hours.Again, degree of modulation is 65% when initial, is 63% after the accelerated test.
Again, after 1000 hours, with above-mentioned the same terms record random pattern, measurement is beated, and finds deterioration about 1%, and is no problem in the degree practicality like this to other recording channels in accelerated test.
The stability that<counterweight is given out light 〉
To these medium, power is brought up to 1.3mW irradiation playback light, there is not deterioration about 10 minutes fully.Then, making power is 1.0mW, shines playback light to 100 repeatedly ten thousand times, and the increase of beating is less than 1%.
(embodiment 5)
In the layer structure of the example of implementing 2 (a1), recording layer adopts Ge 0.05Sb 0.75Te 0.20Optical system with NA=0.6 is estimated.
At α i=0.4, can access minimum beating under the condition of α c=0.3, β m=0.5, Pw=14mW, Pe/Pw=0.5.Beating after rewriteeing for 10 times reaches 10% reluctantly.Also maintain after 1000 times less than 13%.
<accelerated test 〉
To the part of records road of these medium, adopt above-mentioned optimum pulse dividing method, with the random pattern of Pw=14mW record EFM enhancement mode modulation, measurement is beated.Then, these medium are carried out accelerated test under 80 ℃/80%RH hot and humid.After 500 hours, measure beating of this recording channel in accelerated test once more, only deterioration about 2%.
Again, after 500 hours, with condition record random pattern same as described above, measurement is beated, and finds deterioration about 3%, and is no problem in this degree practicality to other recording channels in accelerated test.
The stability that<counterweight is given out light 〉
These medium are increased to 1.0mW irradiation playback light with power, do not have deterioration about 10 minutes fully.Then, making power is 1.0mW, shines playback light to 100 repeatedly ten thousand times, and the increase of beating maintains less than 13% less than 3%.
(embodiment 6)
In the layer structure of embodiment 4, recording layer adopts Ag 0.05Ge 0.05Sb 0.67Te 0.23Optical system with NA=0.6 is estimated.
Measure the relation (α that beats with the pulse dividing method with linear velocity 3.5m/s, Pw=13mW, Pe/Pw=0.5, m=n-1, β m=0.5 iAnd α c).Obtain the contour map shown in Figure 21 (a).α i=0.6, α c=0.35 approximately is an optimum value.In this case, ∑ α i=0.32n (n=3), 0.33n (n=4), 0.33n (n=5) or less than 0.35n (n=6~14).
The relation with power of beating after Figure 21 (b) is depicted as the 1st time, 10 times and 1000 times and rewrites, Figure 21 (c) is the Rtop after rewriteeing for 10 times and the relation of degree of modulation and power.Rewrite the back up to 1000 times and in very wide recording power scope, can keep very little beating, can reach Rtop18% and degree of modulation again more than 60%.
Shown in Figure 22 for the variation after rewriteeing for 10000 times of the beating of Pw=13mW, Rtop and degree of modulation.Except beating than the initial increase about 1%, other do not have deterioration fully.
Beat with similarly to Example 1 method measurements again and the relation of the shortest spot length, the results are shown among Figure 23.In the shortest spot length is under the 0.38 μ m condition, beat less than 10%, and be extraordinary.
To these medium, also estimate, at α with regard to the pulse dividing method of m=n-2 again, i=1.0, can access the characteristic identical under the condition of α c=0.5, β m=0.5 with Figure 21.During N=3, ∑ α i=0.48; During n=4, ∑ α i=0.48n; N 〉=5 o'clock, ∑ α i=0.46n~0.47n.
(comparative example 2)
In the layer structure of embodiment 6, recording layer adopts Ag 0.05In 0.05Sb 0.63Te 0.27
Estimate the relation of beating with linear velocity 3.5m/s, Pw=13mW, Pe/Pw=0.5, β m=0.5, obtain the contour map shown in Figure 24 (a) with the pulse dividing method.α i=1.0 and α c=0.5 be best, ∑ α at this moment iIrrelevant with n, be the certain value of 0.5n.
Figure 24 (b) and (c) be depicted as and the relation of recording power and the rewriting characteristic repeatedly after 1000 times.Though the 1st record beat and power headroom better than embodiment 5 deterioration owing to rewrite repeatedly, it is more serious certainly to beat after 1000 times.
Again the playback luminous power is increased to 1mW, the deterioration of beating about 5 minutes is increased to tens percent.This difference can not illustrate with the difference of the recording sensitivity of 0.5~1mW.The main cause of playback light deterioration is the temperature rise about 50~100 degree, can know that it is resultful for the thermal stability of improving the amorphous state spot that the present invention adds Ge.
(comparative example 3)
Layer structure adopts bottom protective seam (ZnS) 0.8(SiO 2) 20Thickness is 90nm, recording layer GeO 2Sb 2Te 5Thickness is 21nm, upper protective layer (ZnS) 80(SiO 2) 20Thickness is 23nm, reflection horizon Al 0.995Ta 0.005Thickness is 200nm.
During record, be that small adjustment is carried out on the basis, make under the condition of various spot length and linear velocity, to access minimum beating with the pulse dividing method shown in Figure 10 (a).
For these medium, as shown in figure 25, adopt α i=α c=α 0=0.3~0.4, is the strategy of certain value and β m=1.0, can accesses approximate minimum beating.Again, Pw=13mW, Pe/Pw=0.4 (Pe=5mW) and Pb=2.0mW are optimal recording power, and this ratio of Pb/Pe=0.4 is higher.This is because must keep TL among Fig. 9 in a certain higher degree in the recording layer of this comparative example.
Can deterioration even Pb less than 1mW, beats also; Even Pb surpasses 3mW, the still deterioration of beating.
Based on this pulse dividing method, again corresponding to spot length to α 0Carry out the pulse width adjustment of the precision of 0.02 size, the same with embodiment 2, measure relation with spot length.The results are shown among Figure 26 (a).Again, measure when rewriteeing and the linear velocity relation, the results are shown among Figure 26 (b).
With the linear velocity relation is to change the reference clock signal cycle corresponding to linear velocity, and making the shortest spot length is 0.4 μ m, resets and always carries out with 3.5m/s.Again, about with the relation of linear velocity, provided after rewriteeing for 10 times beat and utilize DV to wipe after this after beating when carrying out 1 regenerative recording.
Shown in Figure 26 (a), when the shortest spot length was 0.4 μ m, beating was 10%, and the shortest spot length is short again, the rapid deterioration of then beating.
Again, shown in Figure 26 (b), line speed record is the 5m/s deterioration of beating when above.But, in case under the record case after DC wipes, beat and reduce more than 2~3%.Can think that according to this situation to cause temperature to rise inhomogeneous owing to so-called crystalline state and amorphous absorptivity difference, thereby produce and wipe bad or the distortion of amorphous state spot shape, the deterioration of beating.
Also have, beating after rewriteeing with linear velocity 7m/s is more than 20%, but DC wipes the back record, and beating is about 15%.Thereby can think that beating during high linear speed seriously is not because do not select suitable pulse dividing method.
This recording layer is original in there being coarse grain to beat seriously, adds when rewriteeing more than the linear velocity 5m/s, and former spot is wiped insufficient, and wiping beating of afterwards writing down with DC has difference, and its influence obviously displays by this difference.
Also have, when previous embodiment 2 (g1) medium were rewritten with 7m/s, the difference of beating when wiping the back record with DC was less than 0.5%.
Adopt Ge 2Sb 2Te 5Such GeTe-Sb 2Te 3Under the situation of the recording medium of pseudobinary alloy recording layer, 4 layers of structure that adopt protective seam/recording layer/protective seam/reflection horizon to constitute, with the high linear speed more than 5~6m/s, it is no problem that DC wipes laggard line item as mentioned above, but the deterioration of beating when rewriteeing.Therefore, beat, must increase light absorbing zone etc. again, carry out absorptivity compensation etc. with corresponding in order to reduce.
(comparative example 4)
In embodiment 2 (g1), recording layer adopts Ge 0.15Sb 0.64Te 0.21Initial crystallization is difficulty very, repeatedly shines initialization finally behind the initialization light beam, measures and beats rewriteeing the back, can not obtain beating below 13% but how to change the pulse dividing method in the scope of Figure 10.Again, if constantly rewrite the increase a few percent of then between 10 times to 100 times, beating repeatedly.
(comparative example 5)
In the layer structure of embodiment 2 (g1), recording layer adopts Ge 0.05Sb 0.80Te 0.15, with 7m/s, α i=0.4, the condition of α c=0.3, β m=0.5, Pw=14mW, Pe/Pw=0.5 can access and be approximately minimum beating, but after rewriteeing for 10 times, beats near about 11%, is more than 13% after 1000 times.
<accelerated test 〉
To the part of records road of these medium, adopt above-mentioned optimum pulse dividing method, with the random pattern of Pw=14mW record EFM increase type modulation, measurement is beated.Then, these medium are carried out accelerated test under 80 ℃/80%RH hot and humid, after 500 hours, measure beating of this recording channel in accelerated test once more, deterioration about 3% reaches more than 13%.
Again, after 500 hours, with condition record random pattern same as described above, measurement is beated, and finds deterioration about 5% to other recording channels in accelerated test, and degradation speed is fast.
The stability that<counterweight is given out light 〉
To these medium, power is increased to 1.0mW irradiation playback light, beating after 10 minutes increases by 3%, and very unstable.And the trend that has degree of modulation decline, spot to disappear.
(embodiment 7)
To embodiment 2 (a1) medium, from 1 times of speed (linear velocity be 3.5m/s, reference clock signal period T=38.2nsec) to 2.25 times of speed (7.9m/s, T=17nsec), establish α in all linear velocities iT=τ i=19nsec and α cT=τ C=11nsec is certain value, and T and linear velocity are inversely proportional to, and the EFM enhanced signal is carried out record.Again, with α i+ β I-1The β of=1.0 decision certain values iAnd only change the interval β m of last break impulse, make the slow more β m of linear velocity long more.
In such pulse dividing method, in the gate signal generation sequential key diagram of Figure 11,, produce a τ as long as (add certain delay sometimes) synchronously with the reference clock signal period T iThe fixed width pulse (Gate1) of=19nsec and n-2 τ CThe fixed width pulse (Gate2) of=11nsec gets final product, adds as long as the Gate3 that only makes decision final cutting pulse width corresponding to change of line speed, can simplify pulse generating circuit like this, and be desirable.Moreover, in the present embodiment,, be certain value owing to recording power Pw=13.5mW, Pe=5mW, Pb=0.5mW, therefore pulse generating circuit is simplified very much.Here, on-line velocity satisfies ∑ α during less than 5m/s iTherefore=0.47n can fully suppress fire damage.
Gathered the numerical value of beating when under each linear velocity, changing β m in the table 5.V represents datum velocity 3.5m/s in the table.The wavelength of laser head is 637nm, NA=0.63.Though jitter values itself and embodiment 2 can change the situation of pulse dividing method like that more flexibly and compare weakerly, can access approximately numerical value less than 10% from 1 times of short-term training to 2.25 times speed.
Here establish 2 times of β when fast HM=0.3,1 times of β when fast LM=0.6 (with the square point that is surrounded) as can be seen if make the variation that is inversely proportional to of β m and linear velocity, then can access under each linear velocity of 1 times of speed to 2 times speed less than 10% beat.Moreover, in the present embodiment, make the surplus of β m less, get β m=0.2, be certain value, also can obtain less than 10% beat from 1 times of speed to 2.25 times speed.Can simplify the pulse generating circuit that can change with linear velocity like this.
Again, if on recording medium, utilize the groove of concavo-convex hole or modulation crawl signal record Pb, Pe/Pw, Pw, τ in advance 0, τ cAnd (β LM, β HM), then can the linear velocity when rewriteeing determine the best titime condition automatically.
(embodiment 8)
Layer structure taken off portion's protective seam (ZnS) 80(SiO 2) 20Thickness is 215nm, recording layer Ge 0.05Sb 0.69Te 0.26Thickness is 19nm, upper protective layer (ZnS) 80(SiO 2) 20Thickness is 20nm, reflection horizon Al 0.995Ta 0.005Thickness is 200nm.
With the linear velocity is 3.5m/s, and establishing the pulse dividing method is α i=0.5, α c=0.35, β m=0.5, Pw=11mW, Pe=6.0mW and Pb=0.5mW change the reference clock signal period T the shortest spot length (3T spot length) are changed to carry out record from 0.4 μ m to 0.25 μ m.When the spot length of 3T spot is 0.4 μ m, T=38.2nsec; When spot length is 0.2 μ m, T=19.1nsec.The recording laser wavelength is 637nm, NA=0.63.
Because this laser focusing has Gaussian distribution, therefore only utilize the high-temperature part at center, just can more than optical resolution, carry out high density recording.
Utilize wavelength 432nm, NA=0.6, power to reset to recording section for the blue laser of 0.5mW.This laser is to utilize nonlinear optical effect to produce from the laser of the about 860nm of wavelength.In this layer structure, even 432nm also can access degree of modulation greater than 50% big degree of modulation.
Shown in Figure 28 is to utilize the optical system of recording 637nm, NA=0.63 to carry out playback time and utilize 432nm, NA=0.6 optical system to carry out the relation of beating of playback time and the shortest spot length.Make the setting value optimization of balanced device in the measurement as far as possible at each measurement point.This recording medium blue laser playback time as can be known is even the shortest spot length 0.3 μ m also can access less the beating less than 13%.
(comparative example 6)
In the layer structure of embodiment 2 (a1), recording layer adopts Ge 0.05Sb 0.64Te 0.31
Utilize wavelength to carry out records appraisal for the optical system of 637nm, NA=0.63.On-line velocity is 3.5m/s, establishes m=n-1, α i=0.4, α c=0.4, β m=0.4, Pb=0.5nW, Pe=4.5mW are certain value, only change Pw and carry out regenerative recording, and one until the 10th time.Figure 27 (a) is depicted as the relation with recording power of beating at this moment.Among the figure, 1write refers to not the 1st record of record disc, and 1DOW refers to the 1st rewriting, and 10DOW refers to the 10th rewriting.
Then, make Pw=8.5mW, be certain value, only change Pe and carry out regenerative recording, until the 10th time.Figure 27 (b) is depicted as the relation with erase power of beating at this moment.
Under any situation, can both obtain very little beating at the 1st record (1write), even but rewrite the sharply deterioration of beating also for 1 time.The recording layer of this comparative example form be among Fig. 3 than the composition of the richer Te of straight line A, owing to crystallization rate can not get enough ratios of wiping slowly, thereby can think and can not obtain enough rewriting characteristics.
(embodiment 9 and comparative example 7)
Recording layer in the layer structure of embodiment 2 (a1) is formed shown in table-6 to be changed.By with Ge 0.05Sb 0.73Te 0.22Target is measured to change Ge with the Ge sputter.
Utilize the optical system of wavelength, establish m=n-1, Pb=0.5mW, β m=0.5, change α for 637nm, NA=0.63 i, α c, Pw and Pe, seeking beats after rewriteeing for 10 times is the condition of minimum.
Forming resulting minimum with various recording layers beats as shown in table 6.Along with the increase of Ge addition, the increase of beating when Ge surpasses 10 atom %, is 14% beating of 2 times of speed, and is very high.
Again, these medium are carried out accelerated test under the condition of 80 ℃/80%RH, compare with embodiment 9 (a), embodiment 9 (b) reaches and (c) omits, that is to say, after 2000 hours, read the signal indicating that writes down before the accelerated test in accelerated test, any situation of embodiment 9 (a)~(c), the only deterioration about 1% of beating all.
Again, the initial modulation degree of embodiment 9 (a)~(c) is also can obtain 58~59% degree of modulation after the accelerated test in 61~63%, 2000 hours.Reflectivity does not almost completely change yet.Particularly embodiment 9 (b) reaches (c), has increased less than 0.5%.
Then carry out Ge 0.05Sb 0.73Te 0.22Target adds Ta with the Ta sputter.As a result, when adding the Ta of 1~2 atom % with respect to GeSbTe, obtain minimum beating.
(embodiment 10 and comparative example 8)
In the layer structure of embodiment 2 (g1), recording layer adopts the GeSbTe that adds In.In is by adding with GeSbTe target sputter InSbTe.It is that embodiment 10 (a) is Ge that each recording layer is formed 0.05Sb 0.74Te 0.21, embodiment 10 (b) is In 0.023Ge 0.048Sb 0.719Te 0.21, embodiment 10 (c) is In 0.053Ge 0.044Sb 0.688Te 0.215, comparative example 8 is In 0.118Ge 0.041Sb 0.617Te 0.224
Estimate beating of these medium and the results are shown among Figure 29 (a) and (b), (c), (d) of the relation of power.Upper part is the situation of line speed record 3.5m/s, and lower part is the situation of line speed record 7.0m/s.
The optical system of utilizing all is 637nm and NA=0.63.When linear velocity is 3.5m/s, establish α i=0.6, α c=0.35, β m=0.5; When linear velocity is 7m/s, establish α i=0.4, α c=0.4, β m=0.5.Pb=0.5mW is certain value.Pe is two numerical value, is certain value, only changes beat relation with Pw of Pw measurement.The Pw surplus was improved significantly when the In amount was added 2~5 atom % left and right sides.But,, compare the deterioration on the contrary of beating with the situation of not adding if surpass 10 atom %.
Again, rewrite beating after 1000 times,, all less than 10%, and, then all surpass 13% under two kinds of linear velocity situations under the situation of two kinds of linear velocities at comparative example 8 for embodiment 10 (a)~(c).
<accelerated test 〉
For the medium of embodiment 10 (b), under 80 ℃/80%RH environment, carry out accelerated test.Implement accelerated test and reach 2000 hours.The only deterioration about 1% of beating of the signal of record before the accelerated test.
And the initial modulation degree is also can access 57% degree of modulation after the accelerated test in 61%, 2000 hour.Reflectivity does not almost completely change yet.
The deterioration of beating when after 2000 hours non-recorded part newly being write down is about 3%, and is no problem fully in this degree practicality.
(embodiment 11)
In the layer structure of embodiment 2 (g1), forming recording layer on the polycarbonate substrate of the groove shape with table-7 is In 0.03Ge 0.05Sb 0.71Te 0.21Disc.Separation is 0.74 μ m.
As the wobble modulations mode, be that carrier cycle Tw is 32 times the 2 value phase modulation (PM) of reference data clock signal period T=38.2nsec.Here the swing of so-called phase modulation (PM), as shown in figure 30,0 or 1 corresponding with digital data signal is the phase shifts π that makes oscillatory wave.
That is to say that the unmodulated carrier of frequency f c=1/Tw=1/ (32T) (cosine wave (CW) or sine wave) switches to 1 or from 1 switch to 0 with numerical data from 0 by the address, just in time phase shifts π.Because 0,1 of numerical data is switched, period T d is shorter than Tw, and Td is integer/one of Tw, even therefore phase shifts π, trochoidal wave form is variation continuously also.
The desirable part of this modulator approach is, with ATIP (Absolute Time in Pregroove, be the pre-groove absolute time) used frequency (FM) modulation difference, the frequency of crawling is certain, and be the high frequency modulated of 32T with the cycle, therefore it is synchronous to set up the rotation of disc with reference to the clock signal of swing, simultaneously can with wobble clock signal direct generation data clock signal synchronously.
In order to change phase place with modulates digital data like this, adopt the ring modulator that has among Figure 31 for example.Corresponding generating positive and negative voltage ± the V that adds of numerical data with 0 and 1.When making the pressing mold stamper, laser that resist exposure uses is exposed along the radial direction one side of simultaneously crawling according to the trochoidal wave form of 2 value phase modulation (PM) between ± Vw voltage.At this moment by the ring modulator output wave is added on the EO modulator, can make exposure light bundle hunting.
Explain detailedly a little below.If the signal Vwcos (2 π fct) of cycle cos (2 π fct) inputs on the unmodulated carrier input terminal, then the output terminal of input transformer occur Vwcos (2 π fct) and-two carrier signals of Vwcos (2 π fct).If numerical data just be input as (+V), then D1 and D1 ' conducting, carrier wave Vwcos (2 π fct) remains untouched by D1, occurs modulation on lead-out terminal.And-carrier wave of Vwcos (2 π fct) is through behind the D1 ', utilizes the transformer of outgoing side anti-phase, becomes Vwcos (2 π fct), and the output addition with by D1 obtains the output of Vwcos (2 π fct).
That if numerical data is input as is negative (-V), i.e. D2 and D2 ' conducting, then the signal of Vwcos (2 π fct) is delivered to the downside of output transformer by diode D2, and at output terminal that it is anti-phase, modulating wave becomes-Vwcos (2 π fct).
On the other hand, output at input transformer is-carrier wave of Vwcos (2 π fct) is added to the in-phase input end of output transformer by diode D2 ', therefore, keep the constant modulating wave output terminal (maintenance-Vwcos (2 π fct) former state is constant) that appears at of polarity.Thereby the carrier wave in the path by diode D2 and D2 ' synthesizes-Vwcos (2 π fct), modulating wave occurs at output terminal.
Under the situation of ring modulator, be just or negative according to numeral input, to lead-out terminal output Vwcos (2 π fct) or-Vwcos (2 π fct).
Tiao Zhi trochoidal wave form is input to the EO modulator like this, just can make exposure light bundle hunting.
In the present embodiment, wobble amplitude is all got 60nm (peak value is to peak value).
Under the situation that only is recorded in the medium in the groove, with respect to record reproducing light wavelength lambda=637nm, substrate refractive index n=1.56, the ideal range of groove depth is, is limited to λ/(20n)=20.5nm down, on be limited to λ/(10n)=40.8nm.
Adopting wavelength when these medium are estimated is the optical system of 637nm, NA=0.63.
Identical with embodiment 2, with m=n-1, α i+ β I-1=1.0 (2≤i≤m), α i(the recording impulse dividing method of 2≤i≤m) carries out=α c=certain value, when on-line velocity is 3.5m/s, establishes α i=0.5, α c=0.3, β m=0.5, Pw=13mV, and Pe=6mW; When on-line velocity is 7m/s, establish α i=0.4, α c=0.35, β m=0.5, Pw=14mV, Pe=7mW.
At first, in groove, carry out record, measure R top and degree of modulation with linear velocity 3.5m/s.Beating with 3.5m/s and 7m/s survey record signal again.Show the result in table-8.
At first, embodiment 11 (k) has the very shallow groove of degree of depth 18nm, almost can not detect push-pull signal, can not carry out tracking servo.And, evenly form shallow like this groove, also very difficult in moulded section, it is very unstable in fact to observe tracking servo signal.
Figure 32 (a) reaches the relation that (b) is depicted as degree of modulation and Ttop and groove shape.Embodiment 11 (h)~(j) has the groove of degree of depth 42nm, compares with the situation of degree of depth 27nm, and reflectivity reduces significantly, and low more than 5%, this is unfavorable.Special under the narrower situation of groove, degree of modulation descends, and when width was 0.23 μ m, even the degree of depth is 35nm, degree of modulation reduced also very remarkable.
Also have, present embodiment is got identical layer structure, but the degree of depth adopts the high layer structure of reflectivity for the compensatory reflex rate reduces when being 42nm, and then the degree of modulation reduction is more remarkable.That is to say that the degree of depth is that the groove of 42nm is not suitable for record in the groove.
Groove depth is under the above situation of 40nm, and during less than 0.3 μ m, swinging signal obviously seals in recording data signal in groove width.Compare greater than the situation of 0.3 μ m with groove width, when on-line velocity is 3.5m/s, beat deterioration more than 1~2%; When on-line velocity is 7m/s, the deterioration 2~3% of beating.
(examples of implementation 12)
This layer structure taked bottom protective seam (ZnS) 80(SiO 2) 20Thickness is 65nm, recording layer Ge 0.05Sb 0.73Te 0.22Thickness is 16nm, upper protective layer (ZnS) 80(SiO 2) 20Thickness is 20nm, the 1st reflection horizon Al 0.995Ta 0.005Thickness is 40nm, and the 2nd reflection horizon Ag thickness is the structure of 70nm.
From bottom protective seam to the 1 reflection horizon is not break away from vacuum condition to make with sputtering method, and after the 1st reflection horizon film forming, open atmosphere was placed after several minutes, formed the 2nd reflection horizon with sputtering method in a vacuum again.
After the 2nd reflection horizon film forming, UV cured tree is referred to as overlayer lamination 4 μ m with spin coating method.Two disc coating layers that make are pasted relatively.
The 1st reflection horizon film forming is to arrive 4 * 10 in vacuum tightness -4Pa is following, carry out under the condition of Ar pressure 0.55Pa.Specific insulation is 55n Ω m.Impurity such as oxygen, nitrogen is lower than the detection sensitivity that detects with the beam split of x-ray excitation photoelectron, can think and all add up approximately also less than 1 atom %.
The 2nd reflection tunic is to arrive 4 * 10 in vacuum tightness -4Pa is following, carry out under the condition of Ar pressure 0.35Pa.Specific insulation is 32n Ω m.Impurity such as oxygen, nitrogen is lower than the detection sensitivity with x-ray excitation photoelectron light, can think and all add up approximately also less than 1 atom %.
Using wavelength is 0.60 optical system as 637nm, NA, with linear velocity 3.5m/s, adopt α i=0.4, the pulse dividing method of α c=0.35 and β m=0.5 is measured beating after rewriteeing for 10 times, and obtaining with Pw=11mW, Pe=6.0mW, Pb=0.5mW the time that minimum beats is 6.5%.
After these medium being placed on hot and humid following 500 hours of 80 ℃/80%RH, carry out record more equally, do not find deterioration fully.
(embodiment 13)
Make the pressing mold that forms spiral groove, described spiral groove is separation 0.74 μ m, groove width 0.3 μ m, groove depth 40nm, have the groove of swing, based on this pressing mold, utilize spray up moulding to form the polycarbonate resin substrate of diameter 120mm, thick 0.6mm again.
Shown in table-9, with radius 22.5mm to the 36mm of 58.5mm as recording areas, recording areas is divided into 255 recording strips (zone).Each recording strip comprises 191 roads.
It just in time is the 191st road that the setting recording bandwidth makes each recording strip terminal, so the width of each recording strip is not accurately to be 36/255.Therefore, the outermost terminal of recording areas is 58.54mm.
If channel bit length is 0.133 μ m, obtaining reference clock signal under the on-line velocity 3.49m/s is 26.16MHz (T=38.23nsec).Be set on each recording strip center radius 9 times hunting period for channel bit length.Its physics cycle is 1.2 μ m.
At first calculate channel bit length sum and swing sum on each recording strip center radius, making contained channel figure place or the swing number of interior per 1 circle of same recording strip is certain value.
As shown in table 9, in recording strip top and terminal, its channel figure place or swing number are certain, and precision is ± %.That is to say, can realize and the identical permanent line density record of CLV mode, satisfy the standard of read-only DVD fully in the ZCAV mode.
According to above-mentioned prerequisite, allow the linear velocity that can access 3.49m/s on disc each recording strip center radius of when rotation, at this moment just in time be 9 times of DVD data base clock signal period T=38.23nsec hunting period.
With the rotation of this medium, making the linear velocity on the recording strip center radius of inner ring recording strip of table 9 is 3.49m/s, uses as the medium of ZCAV mode.The carrier cycle of resetting according to the swing of each recording strip in the CAV rotation is shortened to 1/9, generate the data base clock signal Tq in each recording strip, carry out the data recording of EFM enhancement mode modulation again according to this clock signal.
Playback time is if as described belowly reach rotation synchronously, and the data base clock signal frequency that the data according to record are generated is 26.16MHz, then in each regional channel bit length deviation less than ± 1%, in fact can carry out the playback of CLV mode smoothly.
That is to say, utilize quartz (controlled) oscillator to produce said reference clock signal 26.16MHz (T=38.23nsec), the phase place of this phase place with the data base clock signal that generates according to the data that write down compared, sharp common PLL (Phase Locked Loop, being phaselocked loop) control mode finely tunes rotational speed, makes both synchronous.
Utilizing the Spin Control of this PLL control in the playback of present DVD-ROM, is of great use intactly adopting on this mode this point.
(embodiment 14)
In the layer structure of embodiment 2 (a1), Al is adopted in the reflection horizon 0.975Ta 0.025Specific insulation is 220n Ω m.Thickness changes between the 400nm at 200nm, makes a plurality of samples, and is identical with the measurement of table-3, adopts the optimum pulse dividing method among Figure 10 (a) respectively, carries out pulsation measurement.About thickness 300nm, obtain beating of 12% minimum.Compare with it, the reflection bed thickness, thin, all can only obtain bigger beating.
(embodiment 15)
In the layer structure of embodiment 11 (a), the upper protective layer thickness adopts 23nm.
On these medium, carry out record in the groove.The employing wavelength is the optical system of 405nm, NA=0.65, generates the about 0.5 μ m (1/e of Gaussian beam of spot diameter of sub-circular 2The diameter of intensity) light beam, the substrate thick by 0.6mm carries out recording playback.
Is that the EFM enhancement mode modulation signal of 0.25 μ m carries out record with linear velocity 4.86m/s to the shortest spot (3T spot) length.
With the recording impulse dividing method identical, establish m=n-1, α with embodiment 2 i=0.5, α c=0.38, β m=0.67 carry out 10 times with Pw=9.5mW, Pb=0.5mW, Pe=4.0mW and rewrite, and beat this moment is 10%.
Carry out recording playback with blue laser, can know, compare, also can carry out higher-quality record with the situation of embodiment 7.Again, even with the medium of existing red laser matching design, also can remain untouched and carry out recording playback with blue laser, seek to realize densification.
(embodiment 16)
In the layer structure of embodiment 2 (a1), recording layer adopts Ga 0.05Ge 0.05Sb 0.68Te 0.22Medium.Initialization is also the same with embodiment 2 (a) to be carried out, and measures and utilizes wavelength to carry out for the optical system of 637nm, NA=0.63.
Is that the EFM enhancement mode modulation signal of 0.4 μ m carries out with linear velocity 3.5m/s to the length of the shortest spot 3T.Adopt the recording impulse strategy identical, establish m=n-1, α with embodiment 2 i+ β I-1=1.0 (2≤i≤m), α i=α c=certain value (2≤i≤m), establish α i=0.5, α c=0.3, β m=0.5 adopt Pw=13.5mW, Pe=6.0mW, Pb=0.5mW, and the counterweight write attribute is estimated.The 1st record (be not rewrite), rewrite for 10 times, rewrite for 100 times and 1000 rewriting situations under, beating is respectively 6.9%, 6.7%, 7.0% and 7.3%, is reasonable.
With linear velocity 7.0m/s, establish α equally again i=0.4, α c=0.35, β m=0.5, with Pw=14.0mW, Pe=7.0mW, Pb=0.5mW, the counterweight write attribute is estimated.Under the situation of the 1st record (not being to rewrite), 10 rewritings, 100 rewritings and 1000 rewritings, beating is respectively 7.4%, 7.7%, 8.0% and 8.5%, is reasonable.
Degree of modulation can both obtain 55~60% value.
These medium were placed 1000 hours under the accelerated test environment of 80 ℃/80%RH, carried out record before the test.The deterioration of beating of tracer signal is less than 1% before the accelerated test.Again, degree of modulation obtains 52~57% value.
(embodiment 17)
Identical with embodiment 2, forming spacing on the thick polycarbonate resin substrate of 0.6mm is the swinging chute of 0.74 μ m, and image pattern 5 (b) is such again, forms reflection horizon, the 2nd protective seam, recording layer and the 1st protective seam successively.
Utilize sputtering method to form the reflection horizon Al of thickness 165nm respectively 0.995Ta 0.005, thickness 20nm the 2nd protective seam (ZnS) 80(SiO 2) 20, thickness 16nm recording layer In 0.03Ge 0.05Sb 0.70Te 0.22And the 1st protective seam (ZnS) of thickness 68nm 80(SiO 2) 20
Then, the relative thick glass plate of 0.6mm that is adjacent to the 1st protective seam.Carry out initialization by glass substrate with the laser that linear velocity 5m/s shines about 500mW.
By this glass substrate, utilize wavelength the recording layer irradiating laser to be carried out recording playback for the optical system of 637nm, NA=0.6.Record is to carry out away from a concavo-convex side from the laser light incident side.In the groove among the embodiment 2.
Is that the EFM enhancement mode modulation signal of 0.4 μ m carries out with linear velocity 3.5m/s to the length of the shortest spot 3T.Adopt the recording impulse strategies identical, establish m=n-1, α with enforcement 2 i+ β I-1=1.0 (2≤i≤m), α i=α c=certain value (2≤i≤m), establish α i=0.9, α c=0.35 and β m=0.5 with Pw=12.0mW, Pe=6.0mW and Pb=0.5mW, estimate and rewrite characteristic.After rewriteeing for 10 times, beat be 10.5%, degree of modulation is 61%.
With linear velocity 7.0m/s, establish α equally again i=0.55, α c=0.40 and β m=0.5, with Pw=13.0mW, Pe=5.5mW and Pb=0.5mW, the counterweight write attribute is estimated.10 times rewrite the back, beat is 11.2%, and degree of modulation is 61%.
The optic informating recording medium that adopts the present invention to obtain can rewrite at a high speed, and the spot border is beated little, can carry out highdensity spot length modulated record, and the long-time stability of the spot of formation are very good.
Again, form and layer structure by selecting suitable recording layer, it is good and rewrite the phase-change optical recording medium of good endurance repeatedly to access playback interchangeability with read-only medium.
More particularly, a kind of optic informating recording medium and optic recording method that can be used as erasable DVD disc can be provided, it has the playback interchangeability with so-called DVD disc, in the very wide linear velocity scope that comprises from its standard playback speed 3.5m/s to the 7m/s of speed doubly, can realize that single beam rewrites, even and rewrite more than 10,000 times and also do not show deterioration.
Again, because the linear velocity surplus of medium of the present invention is very wide, even therefore medium are rotated under the situation about writing down, also can overcome because the problem of the recording characteristic difference that the difference of medium Internal and external cycle linear velocity causes in constant angular velocity modes such as CAV mode or ZCAV modes.If adopt the CAV mode, then there is no need to change disc rotation speed in each radial location, therefore can shorten the access time.
Figure S07189627920070405D000621
Table-2
Linear velocity α 1cm Pw/Pe(mW) (%) beats
1.0×(3.5m/s) 0.6T/0.35T/0.5T 13.5mW/7.0mW 5.95
1.5×(5.2m/s) 0.4T/0.35T/0.5T 13.5mW/7.0mW 6.31
2.0×(7.0m/s) 0.4T/0.4T/0.5T 13.5mW/7.0mW 7.57
2.4×(8.4m/s) 0.5T/0.4T/0.5T 13.0mW/7.0mW 8.81
Figure S07189627920070405D000651
Table-5
Figure S07189627920070405D000661
Figure S07189627920070405D000671
Table one 7
Figure S07189627920070405D000681
Table-8
Figure S07189627920070405D000691
Figure S07189627920070405D000701
Figure S07189627920070405D000711

Claims (1)

1. an optic informating recording medium has phase change type recording layer at least on substrate,
As not record and erase status, as recording status, utilizing the shortest spot length is that multiple record spot length below the 0.5 μ m is come recorded information with amorphous portion with the crystalline state of this recording layer part, it is characterized in that,
Described phase change type recording layer is by with M y(Sb xTe 1-x) 1-yAlloy is that the film of principal ingredient constitutes, 0.6≤x≤0.9,0<y≤0.2 wherein, and M is at least a kind among Ga, Zn, Ge, Sn, In, Si, Cu, Au, Ag, Al, Pd, Pt, Pb, Cr, Co, O, S, Se, Ta, Nb and the V,
Utilization from amorphous portion or puddle and on every side the crystalline state portion boundary begin crystal growth caused that recrystallizing of in fact carrying out wiped,
It is that the above 300nm of 40nm is following, specific insulation is the following reflection horizon of the above 150n Ω of 20n Ω m m that described optic informating recording medium has thickness.
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