JP4600434B2 - Optical information recording medium - Google Patents

Description

The present invention relates to an optical information recording medium used in a recording / reproducing apparatus (drive) for an optical information recording medium that writes and reads information by making a relative motion with respect to the optical information recording medium. The present invention relates to an optical information recording medium capable of recording and reproducing a large capacity at a density.

Conventionally, as an information recording medium system for reading information by performing relative motion,
There is a system that uses a disk-shaped medium to perform optical recording or playback. The disc system is roughly classified into a read-only type (ROM type), a write-once type (write-once (R type)), and a recordable type (multiple-recording type (RW type)). In general, the recording density is high for reproduction only and is low for write-once type and recording type. For example, in a DVD system (laser wavelength 635 to 650 nm) that appeared in 1996, a read-only type (DVD-ROM, DVD video) precedes, and its recording capacity is 4.7 GB. On the other hand, the recordable DVD-RAM has a capacity of 2.6 GB, which is about 55% of the capacity of ROM. Although research and development for increasing the capacity of a recordable disc is in progress, a system having the same capacity as a DVD-ROM has not yet been completed.

In the case of the recording type, the recording format on the disk, the material of the recording medium, etc. are important technologies. By the way, the DVD-RAM uses land / groove recording in which both the land and the groove of the optical information recording medium are used for recording. Here, addresses (addresses) necessary for recording and reproduction are recorded by cutting lands and grooves at specific intervals.

FIG. 19 is a plan view showing the fine structure 20 (physical format structure) of the land / groove recording disk. FIG. 19 shows the appearance of the structure when not recorded, and the grooves 21 are formed in parallel. Between the grooves 21, there are lands 22, and information is recorded on both of them when recording. Address pit 2 required for recording and playback
3 was formed by cutting the land 22 and the groove 21. Since this address occupies a certain area 24 together with an accompanying signal, this hinders an increase in capacity. In other words, the limited area could not be used effectively.

For recording materials, considering compatibility with read-only DVD drives,
A phase change recording method that does not use a magnetic head is suitable. However, this method
There is a drawback that the reflectance is significantly lower than that of the read-only type or the write-once type using a dye, and this also causes the recording capacity not to be improved.

By combining and optimizing a fine structure (physical format structure) with high surface area utilization efficiency and a phase change material for high-density recording, there is a possibility that a recording capacity comparable to a read-only DVD may be achieved.

As a format suitable for a large-capacity optical disk, for example, an optical disk that does not have a specific address area such as the area 24 shown in FIG. That is, since there is no address area (area 24), the recording density is set to D.
There is a possibility that it can be improved to the same level as VD-ROM. However, in this method, when the main recording signal is recorded in the vicinity of the address signal, an error may occur due to interference with the address signal, and subsequent rewriting may not be possible, and conversely, the address signal becomes the main recording signal. Leakage interference could cause read errors.
An object of the present invention is to propose a high-density phase-change optical information recording medium (recording disk) in which main recording signals and address signals can be recorded and reproduced without interfering with each other, and in particular, this object is realized. An address signal output range and a specific fine structure such as an address signal are shown by dimensions.
Further, the present invention is not limited to the DVD, and is to represent the fine structure dimensions by a general formula corresponding to a recording / reproducing apparatus using a short wavelength laser under development.

In order to solve the above-mentioned problems, the present invention provides the following disc-shaped optical information recording medium.
1) A sinusoidal modulation groove and land formed at a constant linear velocity in a disc-shaped optical information recording medium in which reproduction light having a wavelength λ is focused by an objective lens having a numerical aperture NA and irradiated with a reproduction spot diameter λ / NA And a support having at least a fine structure having address pits of a certain length arranged in a distributed manner on the land, and a rewritable phase formed on the support. look including change material, non-recording time of the recording layer reflectance is 15% or more of the recording layer resin layer formed on, wherein the phase change material, a high reflectivity when not recorded, A phase change material having a low reflectance that can be read after recording, wherein the recording layer includes an information mark formed in a region on the sine wave modulation groove, the refractive index of the support is n, and the sine wave Modulation group The track pitch of the loop is TP, the depth of the sine wave modulation groove and the address pit is d, the width of the sine wave modulation groove is w, the length of the address pit is AL, and the minimum mark length of the information mark is When ML, the microstructure is TP <λ / NA, ML <λ / NA, 0.05λ / n ≦ d ≦ 0.1λ / n, and 0.35 ≦ w /TP≦0.55, 0.18 <0.14k + 4.11n (d−26) / λ <0.27, and k = AL / ML Optical information recording medium.
2) The disk-shaped optical information recording medium according to 1), wherein the phase change material includes antimony, tellurium, and at least one of gold, silver, indium, aluminum, and germanium.

In the optical information recording medium of the present invention, address pits are dispersedly recorded on lands, and a high-density recording optical information recording medium can be realized by using a phase change recording layer having a reflectance of 15% or more in combination. In particular, the optical information recording medium having an address pit output according to the present invention can minimize the mutual interference between the recording mark in the groove and the address pit signal, and can perform good recording and reproduction. Further, since the dimensions of the disk support microstructure are specified, stable optical information recording medium production and supply is enabled.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The inventor of the present invention has arrived at the present invention as a result of diligent development while keeping in mind that semiconductor lasers of various wavelengths will appear in the future. That is, many trial manufactures and evaluations are repeated, and the same recording capacity (4.7 GB) as that of a read-only DVD is realized at a recording / reproducing wavelength of 635 to 650 nm. It came to establish the method.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a bird's-eye view showing an embodiment of the present invention. The optical disk 1 shown in FIG. 1 is a system for recording information only in the groove 11, and the groove 11 as an information track and an address pit 13 (not shown) described later are concentric or spiral with respect to the disk. Embedded, microstructure 10
Is forming. The cross-sectional view is as shown in FIG.

FIG. 14 is a cross-sectional view of an embodiment of the present invention, illustrating the most basic configuration of the embodiment of the present invention. That is, the optical disk 1 is laminated in the order of the support 2, the recording layer 3, and the resin layer 4. Recording / reproduction by light is performed on the recording layer 3, from which the laser beam (wavelength λ nm) narrowed down by the objective lens (numerical aperture NA) is irradiated, that is, incident from the support 2 side, resin layer Whether the light enters from the 4th side is arbitrary. The light incident path, that is, the optical path has a predetermined refractive index n with respect to the wavelength λ, and the effective optical length is determined by the refractive index n. In FIG. 14, the support 2 is illustrated as an optical path as an example. The fine structure 10 including the groove 11 is embedded in the optical disc 1, specifically, formed on the surface of the support 2. The support 2 and the recording layer 3 are formed in parallel to each other.

FIG. 2 is an enlarged plan view showing a fine structure (physical format) 10 according to the embodiment of the present invention, and schematically shows a state when recording is not performed. Here, the fine structure 10 indicates a physical format of the optical disc 1. Grooves 11 are formed on the support 2 of the optical disc 1 substantially in parallel. In order to extract the clock, each groove 11 is modulated at an integral multiple frequency with respect to the sync frame frequency of the entire system, and has a sine wave shape. This waveform may or may not be synchronized with the adjacent groove.

Address pits 13 are formed in a distributed manner on the lands 12 between the grooves 11 and carry address information. That is, the address pits 13 are embedded in the support 2 in advance so as to bridge the adjacent tracks (in an I shape). Specifically, the sine wave modulation groove 11 and the address pits 13 distributed and arranged between the grooves 11 are formed on the support 2 with the same depth. Since the address pits 13 bridge between the grooves 11 in this way, the address pits 13 can be read when either of the grooves 11 is used. In other words, it is arbitrary whether the inner circumference side is the address or the outer circumference side is the address with respect to the groove. The address pit 13 is arranged at a position where the sine wave groove 11 is deflected to the maximum (within the sine wave apex ± 10 degrees).
Address information is recorded based on the distance between the address pits 13. Therefore, the length (AL) of the address pit 13 itself is constant. FIG. 17 is an information format showing an example of address information. There is a sync bit (synchronization signal) at the beginning, followed by relative address data, and ECC block address data (ECC:
Error correction code). For example, the sync has 1 bit, the relative address data is 4 bits, and the ECC block address data is 8 bits.

FIG. 3 is another enlarged plan view showing the physical format of the embodiment of the present invention, and schematically shows a state after recording on the optical disc 1. The configuration is basically the same as that in FIG. 2, but the information mark 14 is modulated and recorded in the groove 11. The information mark is recorded by phase change recording, i.e., recording layer material change.For example, the unrecorded state is crystalline and the recorded state is amorphous. It can be reproduced by utilizing the low reflectivity of the crystalline. Further, as a reference example, depending on the selection of materials, the low reflectance can be achieved when recording is not performed, and the high reflectance can be achieved after recording.

The information mark 14 is a signal modulated by a known digital code, and is a signal that is an integral multiple of the channel bit (T). Therefore, all signals having the shortest mark length of 2T, 3T, 4T, 5T, etc. can be handled as in the known optical disc. For example, in a signal system in which the shortest mark length is 3T, 8/14 modulation, 8/15 modulation,
Signal systems consisting of signals from 3T to 11T, 3T to 11 such as 8/16 modulation
A signal system composed of signals up to T and 14T signals can be handled.

As described above, in the optical disc 1 according to the embodiment of the present invention, the address pits 13 are distributed and recorded on the lands 12, and the specific area 24 is not provided unlike the land groove system, so that the area utilization efficiency is good. In addition, since the information mark 14 is recorded in the groove 11, it has a structure with little interference with the address pit 13 on the land 12. However, as shown in FIG. 3, the address pit 13 and the information mark 14 may be adjacent to each other, and sufficient attention must be paid to the readability of the address pit 13 and the readability of the information mark 14 after adjacent recording.

By the way, for the material of the recording layer 2 used in the optical disc 1 which is an embodiment of the present invention, a phase change material in which the reflectance of the recording layer 2 is 15% or more is suitable, and preferably a high reflectance of 18% or more. The phase change material is suitable. Particularly suitable is a phase change material which is an alloy containing antimony, tellurium and a metal having a melting point of 1100 ° C. or less and which can provide a large reflectance contrast before and after recording. For example, as a material having practical recording sensitivity and practical signal characteristics (modulation degree, reflectance, jitter, rewritable number), antimony and tellurium are essential components, and gold, silver, copper, indium and aluminum are included in these. A material containing at least one of germanium is desirable. Particularly desirable are silver / indium / antimony / tellurium alloy (AgInSbTe), copper / aluminum / tellurium / antimony alloy (CuAlTeSb), germanium / antimony / tellurium alloy (GeSbTe), silver / germanium / antimony / tellurium alloy (AgGeSbTe), Gold, germanium, antimony, tellurium alloy (AuGeSbTe) and the like.

Here, various dimensions are defined in order to explain the recording / reproducing performance described later. FIG.
In the (unrecorded state), the distance between the center line of the groove 11 subjected to sinusoidal modulation is defined as the track pitch TP, and the width of the groove 11 itself is defined as w.
The length of the address pit 13 is defined as AL. Address pit 13 is land 12
The center line of the address pit 13 and the groove 11
Is approximately TP / 2 (not shown). Further, the groove 11 and the address pit 13 are both engraved at the same depth with respect to the support 2, and although not shown in the drawing, the depth is both d. In FIG. 3 (recording state), the length of the information mark 14 after recording has various lengths due to modulation, and the length of the shortest mark is ML.

Using these phase change materials for high density recording, various microstructure dimensions (TP, d
, W, ML, AL) were prototyped and the recording / reproduction characteristics were evaluated. As a result, the numerical value range of the address output and the fine structure dimension range value of the optical disk 1 of the embodiment of the present invention could be obtained. . In the optical disk and the optical disk drive described as the embodiment of the present invention, the TP is 60 to 7 with respect to the reproduction spot diameter (λ / NA).
The length of about 0% and ML of about 35 to 45% is assumed.

(1) Tracking performance of unrecorded disk Since the information mark 14 having a difference in reflectance is formed in the groove on the recorded disk as shown in FIG. 3, various methods can be used for tracking. For example, DPD tracking or DPP tracking. However, when recording is not performed, only the groove 11 is used as shown in FIG. 2, and the tracking method can be practically only the push-pull method.

The relationship between the groove 11 depth d and the push-pull signal output (PPb) is examined.
It was written in. In addition, it measured about the range of W / TP = 0.35-0.55 here. As shown in FIG. 4, the smaller d is, the smaller PPb is. So-called d = 0
. Although the maximum is 125λ / n (n is the refractive index of the optical path), the tracking itself is stable even with a relatively small PPb. When the limit of tracking of the phase change disk 1 with distributed address pits according to the present invention was actually investigated, Pb
= 0.22, and if it was more than this, tracking was stable. In other words, it is necessary that d ≧ 0.05λ / n.

(2) Information mark reproduction performance
One index of the reading performance of the information mark 14 is jitter. This is obtained by performing reproduction after recording and dividing the fluctuation (standard deviation) in the time axis direction by the clock. The smaller the numerical value, the more stable reproduction is obtained. For example, in the DVD standard, after passing through the equalizer, it is determined to be 8.0% or less.

FIG. 5 shows the measurement of the jitter value (5 tracks, 10 times overwriting) with respect to the groove depth d and the groove width. The groove width is expressed by w / TP, a value obtained by standardizing the width w with respect to the track pitch TP. As shown in FIG. 5, the smaller the groove depth d, the better the jitter. The reason is that the shallower the groove, the higher the reflectivity and the degree of signal modulation, and the relatively lower base noise. The influence of the groove width w / TP on the jitter is relatively small.

In order to obtain a jitter of 8.0% or less, although it depends on the groove width, it is necessary that d ≦ 0.1λ / n. Further, it is necessary that 0.35 ≦ (w / TP) ≦ 0.55. Since the address pit 13 is formed in an I shape with respect to each groove, the width of the address pit 13 itself takes a value of 0.65 to 0.45 in TP ratio.

(3) Address Pit Playback Performance and Interference from Information Marks A four-divided photodetector is used for a pickup of a playback apparatus represented by a DVD player. An address pit signal can be generated efficiently by adding / subtracting / dividing the respective outputs. FIG. 6 is a schematic diagram of the quadrant detector 9 as described above. Corresponding to FIGS. 2 and 3, the vertical axis is the radial direction, and the horizontal axis is the tangential direction (track direction). The reproduction outputs of the quadrant detector are Ia, Ib, Ic, and Id, respectively. Here, Ia and Ib are detectors arranged on the inner peripheral side and Ic and Id are arranged on the outer peripheral side corresponding to FIGS. . In reproduction, the address pits 13 can be reproduced with high contrast by synthesizing the outputs so that (Ia + Ib)-(Ic + Id).

7 and 8 show waveforms reproduced in this way. FIG. 7 shows a reproduction waveform in an unrecorded state, in which address pits 13 are synthesized with the waveform of the groove 11 subjected to sinusoidal modulation and reproduced. Thus, only the address pit 13 can be projected and detected, so that the address can be read. Therefore, a normalized value corresponding to this protrusion can be defined as an unrecorded address pit output. Specifically, a value obtained by dividing the absolute value of (Ia + Ib) − (Ic + Id) by the sum of all detectors, that is, the absolute value of (Ia + Ib + Ic + Id) is defined as an unrecorded address pit output (APb). Address pit output value (AP
b) means the value of the address pit signal component in the unrecorded reproduction signal.
APb = | (Ia + Ib) − (Ic + Id) | / | (Ia + Ib + Ic + Id) |

For accurate measurement, it is desirable to insert a filter to remove various noise components. For example, when measuring the absolute value of (Ia + Ib + Ic + Id),
Insert a low-pass filter with a cutoff of 30 kHz. Conversely, (Ia + I
b) When measuring the absolute value of-(Ic + Id), it is desirable to use an amplifier having a bandwidth of 20 MHz or more.

Since the address pit output value is obtained by the diffraction of the address pit 13, it strongly depends on the depth d and the length AL. If the address pit output value APb is small, it is difficult to read and the error rate tends to increase.
FIG. 8 shows a reproduction waveform in the recording state. The signal of the information mark 14 recorded in the groove 11 is overwritten on the waveform of FIG. This signal is groove 11
On the other hand, since it is superimposed as if it were noise, it greatly affects the reading of the address pits 13. In other words, even if the address pits can be correctly decoded when unrecorded, there may be cases where the address pits cannot be decoded after recording.

The error rate of the address pit before recording was measured for an optical disk manufactured by varying d and AL. Thereafter, random recording was performed on the groove 11, and then the error rate of the address pit was measured again. Note that the reliability condition is that the error rate after recording is less than 5%. FIG. 9 shows the measured values. Here, the horizontal axis is the address pit output value APb, and the vertical axis is the block error rate measured for 1000 ECC blocks or more. Error rate before recording (BE
Rb) and the error rate after recording (BER-a) are plotted together. Thus, the larger the address pit output value APb, the easier it is to read the address pit and the lower the error rate. Comparing before and after recording, it is easy to read before recording, but after recording, it is easy to cause errors in reading. This is because the recording signal is likely to interfere, and a sufficient APb value is required. From the above, it can be said that the address pit output value APb needs to be 0.18 or more to ensure an error rate after recording of less than 5%. If the signal error rate after recording is 5% in detail, signal signal superposition is considerably observed.
The aperture ratio of the address pits in FIG. 8, that is, Δ / APs in FIG.
There is only%. In other words, it can be said that Δ / APs is required to be 10% or more.

(4) Interference from address pit to information mark Since the address pit 13 and the groove 11 are partially in contact, the address pit 13 may interfere with the reproduction of the information mark 14 after recording. Therefore, the information mark 14 was read for the optical disk having various address pit output values (APb), and the number of errors was measured. FIG. 10 shows the measured values. Here, the horizontal axis is the address pit output value APb, and the vertical axis is the number of PI errors (the number of erroneous block sequences of 1 byte or more for consecutive 8 ECC blocks). It can be seen that errors increase sharply at a certain value of APb. It is understood that the diffracted light of the address pit 13 interferes with the information mark 14 and causes a reading error. For example, since the DVD standard requires that the PI error is 280 or less, the address pit output value APb is suitably 0.27 or less.

(5) Size of fine structure for obtaining desired address pit output value APb As described above, the optical disk and drive of the present invention have a reproduction spot diameter (λ /
For NA), a small TP and a small shortest mark length are assumed. Furthermore (1)
And as examined in (2), the depth sufficiently shallower than the reproduction wavelength is assumed. The conditions of AL and d for obtaining a desired address pit output value APb under such conditions were examined.

Since AL and ML are considered to be relatively the same order in view of mutual interference, it is assumed that k = AL / ML, the value of k and the address pit output value APb, and the value of d and the address pit output. The value APb was examined. As a result, it was found that APb increases as d increases and k increases. Specifically, AP
b can be expressed by the following function.
APb = 0.14k + 4.11n (d−26) / λ

As described above, the address pit output (APb) that does not hinder the actual operation of the recording / reproducing drive has been obtained, and the dimensions (TP, d, w, k) of various microstructures have been studied. The above studies (1) to (5) can be summarized as follows.
In other words, the address pit output value is the address pit signal component of (AP b) Range:
0.18 <APb <0.27
Various fine dimensions satisfying the above address pit output:
0.05λ / n ≦ d ≦ 0.1λ / n and 0.35 ≦ (w / TP) ≦ 0.55 and 0.18 <0.14k + 4.11n (d−26) / λ <0.27
Dimensions d, w, and k satisfying the following relationship at the same time.

According to the optical disc 1 described above , mutual interference between the information mark 14 in the groove and the address pit 13 is minimized, and good recording and reproduction can be performed. Further , according to the optical disc 1 described above , reproduction interference between the information mark 14 and the address pit 13 can be minimized.

Further, since the specific microstructure dimensions of the support body 2 in manufacturing the optical disk 1, and makes it possible to stably manufacture and supply.
Next , a specific method for manufacturing the optical disc 1 will be described with reference to FIG.
A known blank master (resist board) is mastered by a laser beam recorder (LBR) to form the microstructure 10 according to the present invention (FIG. 18a). For this, for example, a recorder with a built-in laser having a wavelength of 458, 442, 413, 407, 364, 351, 325, 275, 266, 257, 244 nm or the like is desirable, and two-beam mastering using a master beam and a sub beam is useful. is there. Specifically, the master beam is used for forming the groove 11 and the sub beam is used for forming the address pit 13. The master beam is sine-wave modulated by passing a deflector (for example, EOD or AOD). Further, the sub beam is intermittently modulated by passing a modulator (for example, EOM or AOM). The mastering by the two beams is preferably performed at the same time because the positional accuracy is insufficient when each is performed independently. In that case, it is necessary to set the interval between the master beam and the sub beam to TP / 2. At this stage, an image is recorded on the blank master, but the shape is not changed.

Subsequently, a known alkali development is performed on the recorded blank master to convert the mastering image into irregularities (FIG. 18b). This shape is the support 2 described later.
And has the same fine structure 10. The glass master is subjected to a known stampering process, that is, a conductive process and an electroforming process to form a stamper (FIG. 18c). This shape has a fine structure in which the unevenness is substantially reversed from that of the support 2 described later.

Then, using the obtained stamper, known forming is performed to constitute the support 2 (FIG. 18d). The material of the support 2 is polycarbonate resin, polysulfone resin, polyphenylene oxide resin, polystyrene resin, polynorbornene resin,
Synthetic resins such as polymethacrylic resins, polymethylpentene resins, various copolymers having these resin skeletons, and block polymers can be used. However, when the support 2 is used as an optical path, as is well known, its optical characteristics, for example, the refractive index (
n) and birefringence should be noted. For example, when the refractive index is n = 1.45 to 1.65 and the birefringence is 100 nm or less in a double pass, compatibility with the DVD can be kept good.

Then, the recording layer 3 is formed on the support 1. Specifically, the recording layer 3 is formed on the microstructure 10 (FIG. 18e). The phase change material which is the main component of the recording layer 3 is as described above, but may be sandwiched between various optical interference films for the purpose of adjusting the optical characteristics, adjusting the heat propagation characteristics, and the like as necessary. For example, SiN which is a dielectric material,
SiC, SiO, ZnS, ZnSSiO, GeN, AlO, MgF, InO, Z
rO is useful, and among them, ZnSSiO (mixture of ZnS and SiO2)
Has a particularly good thermal balance with the phase change recording material. Alternatively, the recording layer 3 may be configured by laminating a known light reflecting film (aluminum, gold, silver, or an alloy containing these) together for the purpose of adjusting the reflectance, adjusting the heat propagation characteristics, and the like. In order to perform high-density recording / reproduction, a known super-resolution mask film or contrast enhancement film may be used in combination. As a method for forming such a film, a known vacuum film forming method such as a sputtering method, an ion plating method, a vacuum vapor deposition method, or a CVD method can be used.
In particular, the phase change material and the sputtering method are compatible with each other and have high mass productivity.

Subsequently, the resin layer 4 is formed on the recording layer 3. This resin layer protects the recording layer 3 chemically or mechanically, and depending on the structure of the optical disc 1, it may be provided with adhesiveness. The material of the resin layer 4 can be selected from an ultraviolet curable resin, various radiation curable resins, an electron beam curable resin, a thermosetting resin, a moisture curable resin, a multiple liquid mixed curable resin, and the like. As a film forming method, a known spin coating method, screen printing, offset printing, or the like can be used.

Above, a method of manufacturing an optical disc 1 has been described. The configuration diagram of the optical disc 1 shown in FIG. 14 is only basic, and various modifications are possible. For example, it may be bonded to another support to increase the strength, or two optical disks 1 shown in FIG. 14 may be prepared and bonded together to form a disk (double-sided disk or double-layer disk).

( Example)
It will be described an example adapted to an optical disk 1 on the disk system using a red semiconductor laser. Note that λ used is 650 nm, and the numerical aperture NA of the objective lens is 0.6. Therefore, the reproduction spot diameter (λ / NA) is 1083 nm (1.083 μm).

The cross-sectional structure of an optical disc 1 shown in FIG. 15. The support 2, the recording layer 3, the resin layer 4, and the dummy support 5 are laminated in this order. Here, the microstructure 10 described later is embossed on the surface of the support 2. Here, the support 2 is an optical path from the laser to the recording layer 3, and its thickness is 0.6 mm. Both the support 2 and the dummy support 5 are made of polycarbonate resin, and the refractive index n at 650 nm is 1.58. The recording layer 3 has a laminated structure mainly composed of a phase change material having a high reflectance when not recorded and a low reflectance after recording. Specifically, the recording layer 3 is laminated by sputtering from the support 2 side in the order of ZnSSiO / AgInSbTe / ZnSSiO / AlTi. The reflectance is 18-30%. With this structure, the recording sensitivity at 650 nm is 7.5 to 14.0 mW. Recording can also be performed with 635 nm light, and the recording sensitivity can be maintained in the range of 7.0 to 13.0 mW, which is almost the same as 650 nm.

The microstructure 10 when not recorded is as shown in FIG. Groove 1
1 has a spiral shape, and its track pitch TP is the same as that of a DVD-ROM.
. It is 74 μm and is sinusoidally modulated. The groove period is recorded at a frequency eight times that of the sync frame. The wave amplitude is arbitrarily set within the range of 9 to 17 nm. Further, because of CLV (constant linear velocity) recording, the phase between adjacent tracks is random. An address pit 13 having a predetermined length AL is carved in accordance with the address value on the land outside the groove 11.

The fine structure 10 after recording is as shown in FIG. The signal to be recorded is an 8/16 modulation signal, and the shortest mark length ML is 0.40 μm. This value is the same as that of the DVD-ROM, and this makes it possible to realize a recording capacity of 4.7 GB on a 120 mm diameter disc (recording range is a radius of 24 to 58 mm). At this time, TP corresponds to 68% of the reproduction spot diameter, and the length (ML) of the shortest mark corresponds to 37%.

Information mark 14 in the groove and address pit 13 do not interfere with each other, and the range of address pit output in which good recording and reproduction can be performed, that is, the dimensions of various microstructures satisfying 0.18 <APb <0.27. The conditions are as follows.
0.05 · 650 / 1.58 ≦ d ≦ 0.1 · 650 / 1.58,
That is, 20 ≦ d ≦ 41 nm and 0.35 ≦ (w / 0.74) ≦ 0.55,
That is,
0.26 ≦ w ≦ 0.41 μm and 0.18 <0.14k + 4.11 · 1.58 (d−26) / 650 <0.27,
That is, 0.18 <0.14k + 0.01 (d−26) <0.27. Here, since ML = 0.4 μm, it can be expressed as 0.18 <0.35AL + 0.01 (d−26) <0.27, that is, 44 <35AL + d <53.

In particular, in order to clarify the range between d and k, the relationship between k and APb is displayed in a graph as shown in FIG. APb at d = 20nm which is the limit of tracking performance
And the limit of APb at d = 41 nm which is the limit of jitter, d, k
Can take a range within the parallelogram shown. That is, (d, k) = (41, 0.
22), (41, 0.85), (20, 2.34), and (20, 1.70). Considering manufacturing variations (manufacturing variation of groove depth d and address pit length AL), (d, k) = (39.5, 0.34), (39.5, 0
. 95), (21.5, 2.23), and (21.5, 1.60).

Since ML = 0.4 μm, FIG. 11 can be rewritten by replacing k with AL. In FIG. 12, the horizontal axis is AL. The scope of the present invention is (d, AL) =
(41, 0.08), (41, 0.34), (20, 0.94), (20, 0.
68). In consideration of manufacturing variations, (d, A
L) = (39.5, 0.136), (39.5, 0.380), (21.5
, 0.892), (21.5, 0.640).

( Reference example )
It will be described an example adapted to an optical disk 1 on the disk system using a green semiconductor laser. Λ used is 532 nm, and the numerical aperture NA of the objective lens is 0.75. Therefore, the reproduction spot diameter (λ / NA) is 709 nm (0.709 μm).

The cross-sectional structure of an optical disc 1 shown in FIG. 16. The support 2, the recording layer 3, the resin layer 4, and the transmission layer 7 are laminated in this order. Here, the microstructure 10 described later is embossed on the surface of the support 2. Here, the transmission layer 7 is an optical path from the laser to the recording layer 3, and the thickness thereof is 0.1 to 0.12 mm. The transmission layer 7 is an acetate resin, and the refractive index n at 532 nm is 1.6. The recording layer 3 is a phase change material having a high reflectance when not recorded and a low reflectance after recording, and is mainly made of CuAlTeSb having a reflectance of 15 to 32%. Specifically, the recording layer 3 has a laminated structure, and is laminated in the order of AgPdCu / ZnSSiO / CuAlTeSb / ZnSSiO from the support 2 side. With this structure, the recording sensitivity at 532 nm is 4.5 to 7 mW.

The microstructure 10 when not recorded is as shown in FIG. The track pitch TP of the groove 11 is 0.468 μm and is sinusoidally modulated. The period of the groove 11 is recorded at a frequency six times that of the sync frame. The wave amplitude is arbitrarily set within the range of 5 to 9 nm. Further, because of CAV (constant rotation speed) recording, the phases of adjacent tracks are accurately synchronized and are always completely parallel to each other.
An address pit 13 having a certain length AL is carved in accordance with the address value on the land 12 inside the groove 11.

The fine structure 10 after recording is as shown in FIG. The signal to be recorded is an 8-15 modulation signal, and the shortest mark length ML is 0.269 μm. As a result, a recording capacity of 11.8 GB on a 120 mm diameter disk can be realized (the recording range is a radius of 24 to 58 mm). At this time, TP corresponds to 66% of the reproduction spot diameter, and the length (ML) of the shortest mark corresponds to 38%.

Information mark 14 in the groove and address pit 13 do not interfere with each other, and the range of address pit output in which good recording and reproduction can be performed, that is, the dimensions of various microstructures satisfying 0.18 <APb <0.27. The conditions are as follows.
0.05 · 532 / 1.60 ≦ d ≦ 0.1 · 532 / 1.60,
That is, 17 ≦ d ≦ 33 nm and 0.35 ≦ (w / 0.468) ≦ 0.55,
That is, 0.16 ≦ w ≦ 0.26 μm and 0.18 <0.14k + 4.11 · 1.60 (d−26) / 532 <0.27,
That is, 0.18 <0.14k + 0.012 (d−26) <0.27.

In particular, in order to clarify the range of 0.18 <APb <0.27, the relationship between k and APb is displayed in a graph as shown in FIG. D which is the limit of tracking performance
= APb limit at 17 nm, and jitter limit d = 33 nm AP
Due to the limitation of b, the length of the address pit can take a range in the illustrated parallelogram. That is, (d, k) = (33, 0.68), (33, 1.32), (17, 2
. 68) and (17, 2.04).

For the embodiment of the present invention above, it has been describes. The above-described embodiment is merely an example of the present invention, and various modifications can be made in accordance with the spirit of the present invention. Various constituent elements can be interchanged with each other without departing from the spirit of the present invention. For example, the laser wavelength used for reproduction or recording / reproduction is 650 nm, but is not limited thereto. For example, 830, 635, 515, 460, 430, 405, 370 nm, and the like are also possible. The lens numerical aperture NA can be 0.4, 0.45, 0.55, 0.65, 0.7, 0.8, 0.85, 0.9, etc., in addition to 0.60. Further, a numerical aperture of 1 or more typified by a solid immersion lens is also possible.

Further, the microstructure 10 shown in FIG. 2 is for explaining only the main part of the present invention in order to simplify the description. In addition to the groove, land, address pit, etc. shown in FIG. It can be chopped. For example, as the fine structure of the support 2, a pit row for carrying a lead-in signal and a pit row for preventing dump copy and forgery are combined with an inner peripheral portion, for example, an arbitrary radial width within a range of 15 to 24 mm. It may be recorded. Further, a write-once information management area called BCA (described in US Pat. No. 5,617,408) may be similarly provided in the inner periphery.
Moreover, the thickness of various layers, its internal structure, external dimensions, and constituent materials can be changed as needed.

It is a bird's-eye view which shows the Example of this invention. 1 is an enlarged plan view showing a microstructure (physical format) 10 according to an embodiment of the present invention. It is another enlarged plan view which shows the physical format of the Example of this invention. It is a figure which shows each relationship between the groove depth d and the output (PPb) of a push pull signal. It is a figure which shows the result of having measured the value of the jitter with respect to groove depth d and groove width. It is a schematic diagram of a quadrant detector. It is a figure which shows the reproduction | regeneration waveform of an unrecorded state. It is a reproduction waveform in a recording state. It is a figure which shows the measured value of the error rate of an address pit. It is the figure which measured the error rate of the information mark. It is a figure which shows the relationship between (k) which is (address pit length (AL) / recording information mark length (ML)), and address pit output value APb. It is a figure which shows the relationship between an address pit length (AL) and an address pit output value (APb). It is a figure which shows the relationship between (k) which is (address pit length (AL) / recording information mark length (ML)), and an address pit output value (APb). 1 is a cross-sectional view of an optical disc 1. FIG. It is a figure which shows the cross-section of the optical disk 1 of an Example . It is a figure which shows the cross-section of the optical disk 1 of a reference example . It is a physical configuration format showing an example of address information. It is a figure explaining an example of the manufacturing method of the optical disk 1 of an Example. It is a top view which shows the fine structure 20 (physical format structure) of a land groove recording type disk.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical disk 2 ... Support body 3 ... Recording layer 4 ... Resin layer 5 ... Dummy support body 7 ... Transmission layer 9 ... 4 division | segmentation detector 10 ... Fine structure 11 ... Groove 12 ... Land 13 ... Address pit 14 ... Information mark 20 ... Fine Structure 21 ... groove 22 ... land 23 ... address pit 24 ... address area

Claims (2)

In a disc-shaped optical information recording medium in which reproduction light having a wavelength λ is focused by an objective lens having a numerical aperture NA and irradiated with a reproduction spot diameter λ / NA,
A support having at least a fine structure on the surface having sinusoidal modulation grooves and lands formed at a constant linear velocity and having address pits of a fixed length arranged in a distributed manner on the lands; and
Wherein formed on a support, seen containing a phase change material that is capable of rewriting the recording layer reflectance at unrecorded is 15% or more,
A resin layer formed on the recording layer;
With
The phase change material is a phase change material that has a high reflectance when not recorded, and a low reflectance that can be read after recording,
The recording layer includes an information mark formed in a region on the sine wave modulation groove,
The refractive index of the support is n, the track pitch of the sine wave modulation groove is TP, the depths of the sine wave modulation groove and the address pit are both d, the width of the sine wave modulation groove is w, and the address pit When the length is AL and the shortest mark length of the information mark is ML,
The microstructure has TP <λ / NA, ML <λ / NA, 0.05λ / n ≦ d ≦ 0.1λ / n, and 0.35 ≦ w / TP ≦ 0. 55, 0.18 <0.14k + 4.11n (d−26) / λ <0.27, and k = AL / ML. Medium.   2. The disk-shaped optical information recording medium according to claim 1, wherein the phase change material includes antimony, tellurium, and at least one of gold, silver, indium, aluminum, and germanium.

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