JPH10188372A - Production of reloadable phase transition type optical memory medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a reloadable phase transition type optical memory medium capable of producing the reloadable phase transition type optical memory medium which is short in the erasing time of recorded information and is stable in a recording state. SOLUTION: A thin film consisting of a material which is an In-Sb-Te-base martial or an In-Sb-Te-Se-base martial formed by substituting part of the Te of this In-Sb-Te-base martial with Se and has the compsn. expressed by the general formula (In)a (Sb)b (M)c (where, an indicating the ratio of In is 4 to 28atm.%; b indicating the ratio of Sb is 17 to 44atm.%, M is Te, or Te+Se; c indicating the ratio of M is 46 to 63atm.% and the atom ratio of Se to the content of Te and Se is <=0.35atm.% when M=Te+Se) is formed on a substrate. Next, this thin film is irradiated with laser pulses, by which the thin film is melted. The molten thin film is rapidly cooled to be made amorphous. A process to crystallize the thin film made amorphous by further irradiating the thin film with the laser pulses successively increased in the pulse width is added, by which the thin film is formed into a memory medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention particularly relates to a rewritable phase-change type optical memory medium capable of manufacturing a rewritable phase-change type optical memory medium having a short erasing time of recorded information and a stable recording state. The present invention relates to a method for manufacturing an optical memory medium.

[0002]

2. Description of the Related Art A rewritable phase-change type optical memory medium has a higher reflectivity to light when a glass material having a certain composition is in a crystalline state than in an amorphous state, and Utilizing the property that a phase change between an amorphous state and a crystalline state can be performed reversibly by applying light energy, this is formed into a thin film on a substrate, for example ( Hereinafter, this is referred to as a recording film), so that a portion in an amorphous state with a small reflectance is a portion where ON information is recorded, and a portion in a crystalline state with a large reflectance is a portion where OFF information is recorded ( Or, a portion where no information is recorded), so-called rewritable, which has an effect of recording certain information, or erasing recorded information and recording new information. Change optical memory device (hereinafter, referred to as a memory element) which is a material used to construct the.

The first requirement of the recording film formed of this rewritable phase change type optical memory medium is (a) the difference between the reflectance in the amorphous state and the reflectance in the crystalline state. The difference is large enough. That is, usually, the degree of modulation (= contrast ratio = difference between the reflectance in the amorphous state and the reflectance in the crystalline state ÷ the reflectance in the crystalline state × 100%) is practically 20% or more. Is required.

Next, in order for the memory element having the recording film to be put to practical use as a rewritable memory element, it is necessary to (b) record certain information, erase it, and record new information. The desired performance must be maintained even if the operation is repeated, and in practice, it is necessary that the number of repetitions be 10 ⁶ or more.

Further, the memory element must be capable of (c) withstanding long-term storage while recording certain information. Practically, the memory element can be stored for 10 years or more under normal storage conditions. It needs to be endurable. In other words, it is necessary that the amorphous state in which information is recorded can be stably maintained at room temperature for 10 years, for example. This means thermal stability from the viewpoint of the physical properties of the glass material. This thermal stability depends on the crystallization temperature (T
x) and the crystallization / activation energy (E). To obtain the above degree of stability, Tx = 120 ° C. or higher and E =
It is required to be 2.0 eV or more.

In general, when information is recorded in the memory element, a laser beam is focused to about 1 μmφ and is irradiated on the recording film formed in a thin film shape to melt the portion and give an emergency command. To make it amorphous.
When erasing recorded information, irradiate the recording film with a laser light output smaller than that at the time of recording, and lower the melting point of the recording film and higher than the glass transition point. This is performed by heating and making the irradiation time longer than that at the time of the recording to make it crystalline.

That is, in such a phase-change type optical memory device, the irradiation time of the laser beam at the time of recording can be made sufficiently short, but the irradiation time of the laser beam at the time of erasing is reduced by the recording film. A relatively long time is required because it takes a certain amount of time or more to effectively crystallize.

The length of the time required for recording or erasing is one of the very important factors that determine the performance of this type of phase change type optical memory device. The longer the time required for erasing, the lower the performance. Therefore, it is required to shorten the erasing time as much as possible. For example, in the conventional device that required several μsec or more as the erasing time,
A laser device dedicated to recording focused at 1 μmφ and a laser device dedicated to erasing (for example, a semiconductor laser device is used) in which the beam is made into an elliptical shape in order to extend the irradiation time to one part. Two laser devices were required, but if the erasing time could be reduced to, for example, 0.2 μsec or less, these recording and erasing could be performed by one laser device, and the optical head would be lightweight and compact. , Access time can be shortened, and the like.

As described above, the rewritable phase-change optical memory medium as the material of the recording film further has the following features: (d) a erasing time can be shortened, in other words, a crystallization time can be shortened. Requested.

In order to satisfy the above conditions (a, b, c, d), development of a rewritable phase-change type optical memory medium of various compositions has been conventionally attempted. Maeda Yoshinori and colleagues reported that the ternary compound In ₃ S
bTe ₂ has a composition of 0.05 μse
c has been reported to be capable of high-speed erasure (Showa
Proceedings of the 62nd National Meeting of the Institute of Electronics and Communication Engineers Semiconductor Materials National Convention
See Volume 1-39).

[0011] In addition, also in the other, (b) Q _x Sb _y T
_ez (where Q is In or Ga, x = 34 to 44 atomic%, y
= 51 to 62 atomic%, z = 2 to 9 atomic%)
-241145), or
(C) a material having a composition of In ₅₀ Sb ₄₀ Te ₁₀ (S
PIE, VoL529, 1985 years, see P51 through 54), further, _{(d) (In 1-x Sb x} ) 1-y M y ( where, together contain Te, Se is Among the M, 55% by weight ≤
A composition having a composition of x ≦ 80% by weight and 0% by weight ≦ y ≦ 20% (see JP-A-60-177446) has been proposed.

[0012]

However, in each of the conventional examples, although some of the conditions (a, b, c, d) required for the rewritable phase-change optical memory medium are satisfied, All of these conditions could not be met. For example, the In ₃ SbTe of the conventional example (a) is used.
_{In the case of 2} , the modulation degree under the condition (a) is 5.0%, which is far below the practically required 20%.

Further, Q _x Sb _y Te of the prior art (b)
_{In z} , the number of repetitions satisfying the condition (c) is 1
0 or less ^three times, far short for more than 10 ⁶ times is practically required.

An object of the present invention is to provide a method for manufacturing a rewritable phase-change optical memory medium capable of manufacturing a rewritable phase-change optical memory medium which eliminates the above-mentioned disadvantages.

[0015]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention of claim 1 provides an In-Sb-Te-based substance,
Or an In-Sb-Te-Se-based material in which a part of Te of the In-Sb-Te-based material is replaced with Se, and represented by the general formula (In) _a (Sb) _b (M) _c ... (I (Wherein, a representing the proportion of In is from 4 to 28 at%, b representing the proportion of Sb is from 17 to 44 at%, and M is T
e or Te + Se, c indicating the proportion of M is 46 to 63 atomic%, and when M = Te + Se, the atomic ratio of Se to the content of Te and Se is 0.35 atomic% or less. ) Is formed on a substrate, and then the thin film is irradiated with a laser pulse to be melted and quenched to become amorphous. A method for manufacturing a rewritable phase-change type optical memory medium, characterized in that the thinned film is subjected to crystallization by irradiating the thinned film with a laser pulse whose pulse width is sequentially increased, thereby making the thin film a memory medium. It is.

A second aspect of the present invention is an In-Sb-Te-based material, or an In-Sb-Te-Se-based material in which part of Te of the In-Sb-Te-based material is replaced with Se. The general formula (In) _a (Sb) _b (M) _c (I) (wherein, a representing the ratio of In is 4 to 28 atomic%, and b representing the ratio of Sb is 17 to M is T
e or Te + Se, c indicating the proportion of M is 46 to 63 atomic%, and when M = Te + Se, the atomic ratio of Se to the content of Te and Se is 0.35 atomic% or less. ) Is formed on a substrate, and then the thin film is irradiated with a laser pulse to be melted and quenched to become amorphous. A method for manufacturing a rewritable phase-change optical memory medium, characterized in that a heat treatment in a vacuum is further performed on the converted thin film to perform crystallization, thereby making the thin film a memory medium.

The invention of claim 3 is an In-Sb-Te-based material or an In-Sb-Te-Se-based material in which a part of Te of the In-Sb-Te-based material is replaced with Se. (In) at each vertex of the triangle in the triangle composition diagram,
(Sb), when taking a (Te or Te + Se), on the diagram this triangular composition, the general formula _{(In Te) x (Sb 2} Te 3-y Se y) 1-x ... (II) ( where, x = A thin film made of a material having a composition within a composition region within 2 atomic% from a straight line indicating the material represented by 0.2 to 0.7, y = 0 to 1.2) on a substrate;
Next, the thin film is melted and quenched to be amorphous, and then the amorphous film is subjected to a crystallization process, thereby making the thin film a memory medium. This is a method for manufacturing a phase-change optical memory medium.

According to a fourth aspect of the present invention, there is provided the method for manufacturing a rewritable phase-change type optical memory medium according to any one of the first to third aspects, wherein the material constituting the thin film comprises 1 g of the material constituting the thin film. Zr, Mo, Ir or Pt
A method for manufacturing a rewritable phase-change optical memory medium, characterized by adding 0.02 to 0.18 g.

The invention according to claim 5 is an In-Sb-Te-based material or an In-Sb-Te-Se-based material in which Te in the In-Sb-Te-based material is partially substituted with Se. The general formula (In) _a (Sb) _b (M) _c (I) (wherein, a representing the ratio of In is 4 to 28 atomic%, and b representing the ratio of Sb is 17 to M is T
e or Te + Se, c indicating the proportion of M is 46 to 63 atomic%, and when M = Te + Se, the atomic ratio of Se to the content of Te and Se is 0.35 atomic% or less. ), Zr, M per 1 g of the substance
A process of forming a thin film containing 0.02 to 0.18 g of o, Ir or Pt on a substrate, melting and quenching the thin film to make it amorphous, and then crystallizing this amorphous thin film Is a method for manufacturing a rewritable phase-change type optical memory medium, characterized in that the thin film is used as a memory medium by adding a thin film.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a rewritable phase-change optical memory medium according to any one of the first to fifth aspects, wherein the target having an InTe composition,
By using a target having a composition of b ₂ Te ₃ and changing the area ratio of the two targets, In, S
A method for manufacturing a rewritable phase-change optical memory medium characterized by changing the ratio of b and Te.

Hereinafter, the present invention will be described in detail.

In the rewritable phase-change type optical memory medium of the present invention, the material constituting the recording layer is represented by the general formula described above.
(1) As apparent from (In) _a (Sb) _b (M) _c , a ternary alloy of In—Sb—Te or In—b—Te—
It is made of a quaternary alloy of Se. In these alloys, the ratio of each metal element is limited as follows.

The amount of In (a) = 4 to 28 atomic% The amount of Sb (b) = 17 to 44 atomic% M (the amount of Te or Te + Se (c) = 46 to 63 atomic% The amount of In (a ) Is limited to 4 to 28 atomic% because
If less than 4 atomic% or more than 28 atomic%, the erase time is 0.2 μm
Because it is longer than se. Also, the amount (b) of Sb is 17-44
The reason for limiting to atomic% is that if it is less than 17 atomic% or exceeds 44 atomic%, the erasing time will be longer than 0.2 μsec.

Further, the amount of M (Te or Te + Se) (c)
The reason why is limited to 46 to 63 atomic% is that when the atomic percentage is less than 63 atomic% or more than 63 atomic%, the erasing time is longer than 0.2 μsec.

When M is Te + Se, the atomic ratio of Se to the total amount of Te and Se is limited to 0.35 or less. The reason is that if it exceeds 0.35, the contrast ratio becomes less than 20%.

Further, in the triangular composition diagram, the general formula (I)
_{I) (InTe) × (Sb} 2 Te 3-y Se y) 1-x ( where,
x = 0.2-0.7, y = 0-1.2) In-S having a composition within 2 atomic% from a straight line indicating a substance represented by
When the material composed of a ternary alloy of b-Te or a quaternary alloy of In-Sb-Te-Se is used, the erasing time under the condition (d) is satisfied.
0.2 μsec or less and other conditions (a, b,
c) is also sufficiently satisfied, and a material obtained by adding 0.02 to 0.18 g of Zr, Mo, Ir, or Pt per 1 g of the material to the above-mentioned material is such that Zr, Mo, Ir, Pt acts as a nucleating agent, In addition to increasing the crystallization speed, the crystal has a function of reducing the size of crystals precipitated during crystallization, so that the problem of unerased recording can be eliminated, and a decrease in contrast ratio can be prevented.

[0027] In the optical memory medium of the present invention, the material consists of a material having a composition represented by the general formula (I) or the general _{formula, (InTe) x (Sb 2} Te 3-y Se y) 1-x ... (II ), For example, InSb ₄ T
_{e 7, InSb 2 Te 4,} In 2 Sb 2 is estimated to have a composition of Te ₅ or the like coexisting materials in the crystalline state and the material of the amorphous state, which is therefore, in a phase-change recording and erasure Without phase separation, the erasing time was extremely short (less than 0.2 μsec), and according to observation by X-ray diffraction, all of these crystals were hexagonal.
onal), which means that the reflectivity is high (modulation degree is 20% or more), and that the material having the above composition has a crystallization temperature Tx ≦ 120 ° C. and a crystallization energy E ≧
It has been confirmed that the stability is 2.0 eV and the stability is extremely high (the number of repetitions: 10 ⁶ or more). In addition, as a result of various experiments, in the general formula (Ι) and the triangular composition diagram, 2 atomic% was determined from a straight line indicating a substance having a composition represented by the general formula.
It has been confirmed that substances having compositions within the composition range within exhibit substantially the same characteristics as each other.

A glass material having a composition obtained by adding 0.02 to 0.18 g of Zr, Mo, Ir or Pt per gram of the material to the material having the above composition has a shorter erasing time and has the other characteristics that the above-mentioned Zr or the like is added. It is confirmed that it is almost the same as the case without.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

Example 1 A glass substrate was used as a substrate, and SiO ₂ was sputtered on this substrate to a thickness of 2000 angstroms by an ordinary sputtering method.

Next, as a sputter target, an alloy target having a composition represented by the formula In ₂₆ Sb ₂₅ Te ₄₉ (the number in the formula represents atomic%) is used and attached to a predetermined position in a high-frequency magnetron type sputtering apparatus. , 2
At a vacuum degree of × 10 ⁻⁶ Torr or less, Ar gas is supplied at 0.005 T
orr, and a high-frequency power of 30 W or less is applied to form a film having a thickness of 800 angstroms.
iO ₂ was formed to a thickness of 3000 Å.

Next, the initialization of the recording film thus created will be described.

A film formed by sputtering as described above is usually in an intermediate state between amorphous and crystalline, as it is (ie, as-deposited). It is considered that this is because the film is formed in an intermediate state where the amorphous state shifts to the crystalline state due to the impact of the electron at the time of sputtering. Such a state is a state in which noise (noise) is recorded. Unless this state is recorded, certain meaningful information cannot be recorded. This state in which nothing is recorded is called initialization.

In short, the initialization can be performed by bringing the recording film in the intermediate state into a crystalline state, which is performed as follows.

First, the recording film is irradiated with a semiconductor laser pulse to be melted and quenched to make the recording film amorphous, thereby eliminating the intermediate state and then heating the recording film with weak light. Crystallize by heating in vacuum. Whether or not the crystal has been crystallized can be easily measured by measuring the reflected light of the reproduction laser pulse.

The physical properties of the recording film thus formed were satisfactory in all physical properties as described below.

Contrast ratio 20% or more Number of repetitions 10 ⁶ or more Crystallization temperature (Tx) 130 ° C. Activation energy of crystallization (E) 2.0 eV Erasure time 0.2 μsec The methods for measuring the above various physical properties are as follows. It is.

Contrast ratio : The reflectance (Ra) in the amorphous state and the reflectance (Rc) in the crystalline state were measured and determined by the following equation.

Contrast ratio (%) = ｛(Rc-Ra)
/ Rc｝ × 100 repetitions : After recording, the reflectance (Ra) is measured, and then after erasing, the reflectance (Rc) is measured.
This was repeated, and the number of times until the contrast ratio decreased to 15% was defined as the number of repetitions.

Crystallization temperature (Tx) : Measured with a high sensitivity differential scanning calorimeter DSC8240B manufactured by Rigaku Corporation (temperature rise rate: 10 ° C./min).

Activation energy for crystallization (E) : 5, 10
The crystallization temperature was determined using three types of temperature rise rates of 20 ° C./min and was calculated by a Kissinger plot. Erasing time : A laser beam having an output of 8 mW is applied to the recording film, and the recording film is melted and quenched to form an amorphous state. Irradiation causes each part to crystallize one after another. After the crystallization process is completed in this way, the laser beam for reproduction of 0.5 mW and 1 μse is sequentially irradiated to the portion subjected to the crystallization process, and the reflected light is measured. If the pulse width of the crystallization laser pulse in a portion where the intensity of the reflected light is saturated is obtained (this can be obtained by associating the irradiation position of the crystallization laser with the irradiation position of the reproducing laser), That is, that is, the erase time to be obtained under this condition.

Such measurements were performed variously by changing the laser output, and the erasing time under each condition was determined. The minimum erasing time thus obtained was taken as the erasing time of this recording film.

Examples 2 to 6 Optical memory media were obtained in the same manner as in Example 1 except that In, Sb, Te and Se were varied variously as shown in Appendix 1 within the scope of the present invention. The obtained optical memory media of Examples 2 to 6 have excellent performance equivalent to that of the memory medium of Example 1 as shown in Appendix 1 (FIGS. 2 to 7) of various physical property values. Was.

Examples 7 to 22 Optical memory media were obtained in the same manner as in Examples 1 to 6, except that predetermined amounts of Zr, Mo, Ir and Pt were added as nucleating agents.

The obtained optical memory media of Examples 7 to 22 are all superior in erasing time to 0.15 μsec as compared with the optical memory media of Examples 1 to 6, as shown in Table 1. Was.

Examples 23 to 28 The points Sb ₂ Te ₃ and InT in the triangular composition diagram shown in FIG.
The straight line connecting to e indicates the composition of the rewritable phase-change optical memory medium according to the third aspect of the present invention.

Here, a triangular composition diagram means that a distance between each side of an equilateral triangle and a vertex opposed to each side is 100%,
By indicating the composition percentage of the element displayed at each vertex opposed to the side by the distance between the point displayed in the triangle and each side, various types of elements formed at each vertex are displayed. FIG. 4 is a diagram showing a substance having a composition of the formula (1) as points plotted in the equilateral triangle. The triangular composition diagram of FIG.
(In), (Sb), (Te or Te + D
e) (see "Illustrated Alloy State Diagram Reader", Toru Yokoyama, February 170, 1982, Ohmsha, pages 170-171).

Hereinafter, how to read this diagram will be briefly described. For example, consider a point (InTe) (also a middle point of a straight line connecting the vertices) on a straight line (which is also one side of the triangle) connecting a vertex (In) and a vertex (Te or Te + Se) of the triangle in the figure.

Now, each side is defined as follows.

First side : a straight line connecting vertex (In) and vertex (Te or Te + Se) Second side : a straight line connecting vertex (In) and vertex (Sb) Third side : vertex (Te or Te + Se) and vertex (Sb)
Then, the composition of the substance represented by the point (InTe) is as follows.

The composition of In ... In corresponds to the above point (InTe)
And the distance (%) between the first side and the third side which is the side opposite to the vertex (In) (however, the third side which is the side opposite to the vertex (In) and the vertex (In)) The distance between
100). In this case, since the point (InTe) is the middle point of the second side, the distance between the vertex (In) and the third side opposite to the vertex (In) is set to 10
When 0 is set, the distance between the point (InTe) and the third side opposite to the vertex (In) is 50,
It can be read that the composition of In is 50%.

Te or Te + Se : Te or Te + Se
Is composed of the point (InTe) and the vertex (Te or Te +
Distance (%) between the second side opposite to Se)
(However, the vertex (Te or Te + Se)
And the second side, which is the side facing the vertex (Te or Te + Se), is assumed to be 100). Also in this case, it can be read that it is 50% as in the case of (In).

Sb ... The composition of Sb is determined by the above-mentioned point (InTe).
And a distance (%) between the first side and the side opposite the vertex (Sb) (however, the second side that is the side opposite the vertex (Sb) and the vertex (Sb)) The distance between
100). In this case, the distance between the point (InTe) and the first side opposite to the vertex (Sb) is 0.
Therefore, it can be read that the composition of Sb is 0%.

That is, the substance represented by the above-mentioned point (InTe) contains 50% of In, 50% of Te or Te + Se, and 50% of Sb.
Can be read as a substance having a composition of 0%.

In FIG. 1, the numbers displayed on each side of the triangle have the following meanings.

That is, for example, the vertex (Te or T
e + Se) and a vertex (In) on a straight line (the first side) are numbers corresponding to the vertex (Te or Te + S
Assuming that the distance from e) to the vertex (In) is 100,
It represents the distance from the vertex (Te or Te + Se) to the point represented by the numeral, whereby a straight line passing through this point and parallel to the third side is planned. In the composition of the substance represented by the above point, the composition of In indicates that the composition is represented by this numerical value. That is, for example, the point (I
All points on a straight line that passes through (nTe) (the displayed number is 50) and is parallel to the third side represent substances whose In composition is 50%. Similarly,
The numbers displayed on the second side and the third side indicate the composition of Sb and Te or Te + Se, respectively.

In FIG. 1, the points indicated by the symbols A, B, C, D and E are represented by the following general formula: (InTe) _x (Sb ₂ Te _{3-y S y} ) _1-x (II) In the general formula when y = 0, (InTe) _x (Sb ₂ Te ₃ ) _1-x indicates the composition ratio of a substance when x = 0.2, 0.33, 0.5, 0.666, and 0.7, respectively. In the following, an optical memory medium was obtained in the same manner as in Example 1 for the composition at each value of x. The obtained optical memory media of Examples 23 to 28 had excellent physical properties equal to or better than those of the optical memory media of Example 1 as shown in Appendix-1.

According to the findings of the present inventors, the reason for obtaining the above results is presumed to be as follows.

Example 23 (in the case of point A (x = 0.2)) When this example is represented according to the above general formula (I), In ₅ Sb ₄₀ Te ₅₅ (atomic%) is obtained. Then, a mixture of crystals represented by the composition formulas of InSb ₄ Te ₇ and Sb ₂ Te ₃ precipitates.

In InSb ₄ Te ₇ , a crystalline substance and an amorphous substance coexist. Therefore, the phase change of recording / erasing does not involve phase separation, so that the required diffusion distance of each atom is short. As a result, the time required for crystallization, that is, the erasing time is considered to be short.

It is also considered that the ternary compound itself becomes crystalline and amorphous and does not involve phase separation, so that the phase change can be performed without difficulty and a high number of repetitions can be maintained.

Further, according to the observation by the X-ray diffraction method,
It is confirmed that the crystal forms of these crystals are all hexagonal.
Has a high refractive index due to a structure in which the particles are densely packed, which is presumed to be a high reflectivity.

Since the crystal form of Sb ₂ Te ₃ is also hexagonal, it is presumed that the reflectance is high, the time required for diffusion is short, and the time required for crystallization is short.

Example 24 (in the case of point B (x = 0.333)) When this example is represented according to the general formula (I), In _8.33
Sb _33.34 Te _58.34 (atomic%), and when this is crystallized, a crystal having a composition represented by InSb ₄ Te ₇ precipitates, but the same characteristics are obtained for the same reason as in the case of point A. it is conceivable that.

Embodiment 25 (Case of Point C (x = 0.5)) When this embodiment is represented according to the general formula (I),
_14.29 Sb _28.57 Te _{57.1 4} (atomic%), and when is crystallized, but precipitates crystals of composition represented by InSb ₂ Te _4, by exactly the same reason as the case of the point A, the same characteristics are obtained It is thought that it is possible.

Embodiment 26 (in the case of point D (x = 0.666)) When this embodiment is represented according to the general formula (I),
_22.22 Sb _22.22 Te _{55.5 6} (atomic%), and when is crystallized, the crystal of the composition represented by In ₂ Sb ₂ Te ₅ is deposited, by exactly the same reason as the case of the point A, the same characteristics Is considered to be obtained.

Embodiment 27 (in the case of point E (x = 0.7)) When this embodiment is represented according to the general formula (I),
_24.14 Sb _20.69 Te _{55.1 7} (atomic%), and when is crystallized, the crystal of the composition represented by In ₂ Sb ₂ Te ₅ is deposited, by exactly the same reason as the case of the point A, the same characteristics Is considered to be obtained.

Embodiment 28 (when x = 0.4) This embodiment is represented by the following general formula (I).
_10.53 Sb _31.58 Te _{57.8 9} (atomic%), and when is crystallized, InSb ₄ Te ₇ when the x = 0.333
And the crystal of InSb ₂ Te ₄ when x = 0.5 are mixed and precipitated.

In this case, since both are similar in atomic arrangement to each other, the distance which must be diffused with the phase change can be shortened, and it is considered that the same characteristics as those of the above-described points can be obtained. A substance having this composition is indicated by a point located between points B and C on a straight line connecting the points Sb ₂ Te ₃ and InTe in the triangular composition diagram of FIG.

Embodiments 29 to 32 Next, Embodiments 29 to 32 in which an optical memory medium is obtained in the same manner as in Embodiment 1 except that Te in the general formula (I) is partially replaced with Se will be described. Generally, Se can be easily replaced with Te. Then, the crystal form does not change by substitution to a certain extent.

Embodiment 29 (x = 0.5 and y = 0.5)
In the case of formula (1), the composition is represented by In _16.67 Sb _33.33 Te _41.67 Se _8.33 (InSb ₂ Te _2.5 Se _0.5 ) (atomic%).
The crystal form of the precipitated crystal was hexagonal. Also, Se
Has a larger covalent bond strength than Te,
There is also an advantage that the crystallization temperature of the amorphous state is increased by substituting the above. However, if y exceeds 1.2, the crystal form changes and the contrast ratio decreases, so it was necessary to set y to not more than 1.2.

As shown in Table 1, the obtained optical memory media of Examples 29 to 32 had excellent performance equivalent to that of the optical memory medium of Example 23. .

In general, it is known that an amorphous material crystallizes quickly when there is a crystal nucleus when it crystallizes. The present invention, etc. As a result of investigating various experiments in view of the fact, in the material expressed by the general formula _{(InTe) x (Sb 2 Te} 3-y Se y) 1-x ... (II), Zr, Mo, Ir or P
It has been found that t can be an effective nucleus.
In this case, it is appropriate to add 0.02 to 0.18 g of Zr or the like per 1 g of the material, and if it is less than that, it does not function as a nucleus, and if it is too much, it changes other characteristics. It has been found to work.

The effectiveness of these nuclear materials was Zr>Mo>Ir> Pt. The effect of shortening the erasing time was １ ／ to ３ (0.1 μsec or less) of the erasing time when Zr was not added in the case of Zr.

Example 33 An alloy target was prepared by adding 0.1 g of Zr to 1 g of the alloy target to the alloy target having the composition of Example 30, and an optical memory medium was obtained in the same manner as in Example 1. The erasing time of the obtained optical memory medium was 0.1 μsec or less, and the crystallization temperature (Tx) was 130 ° C.

Examples 34-35 In Examples 34-35, alloy 1 of each composition was used in the same manner as in Example 31.
An optical memory medium was obtained in the same manner as in Example 1 except that predetermined amounts of Zr, Mo, Ir and Pt were added per g.

As shown in Table 1, the optical memory media of Examples 34 to 35 obtained had an erasing time of 0.1 μsec or less and a crystallization temperature (Tx) of 125 ° C.
That was all.

Example 36 The composition of the alloys of In, Sb, and Te was 8, 32, and 60 at%, respectively. A composition obtained by adding 0.05 g of Ir to 1 g of a material was used as a sputter target. This is an example in which a recording film is formed by a sputtering method in the same manner as in the first embodiment, using the same as the sputtering target in the same manner as in the first embodiment.

The composition of the memory medium thus formed has the general formula (II) (InTe) _x (Sb ₂ Te _3-y Se) _1-x (where x = 0.2 to 0.7, y = 0 to 1.2) Is not on the straight line indicating the substance represented by the following line, but within the composition area within 2 atomic% from this straight line (in the area surrounded by the dotted line in FIG. 1)
It has been confirmed that it has almost the same characteristics as those of the above embodiments (for example, erasing time: 0.15 μsec).

Comparative Example Points F and G in FIG. 1 show materials having compositions outside the scope of the present invention. The present inventors have measured the erasing time for comparison. Are listed below.

Composition of point F (atomic%) In ₁₇ Sb ₁₇ Te ₆₆ Erase time 3 μsec

Composition of point G (atomic%) In ₁₅ Sb ₄₀ Te ₄₅ Erase time 1 μsec

[0083] Phase recording film forming method of the change memory device Next, a phase-change optical memory medium according rewritable to an embodiment of the present invention to form a recording film formed by a phase change memory elements on a substrate The method will be described.

This recording film is formed on the surface of a glass substrate or a plastic substrate by a usual sputtering method or vacuum evaporation method.

When the sputtering method is used, a sputtering target synthesized as follows is used, for example. That is, in a vacuum glove box in which indium (In), antimony (Sb), tellurium (Te), and selenium (Se) having a purity of 5 N or more are substituted with Ar, a predetermined amount is placed in an ampoule made of transparent quartz glass. Into the glass composition, and then add this to 10 ^-5 TO
Evacuate the RR vacuum and seal. Next, this is melted while being mixed well at 850 ° C. for 15 hours in a rocking furnace, and then cooled to obtain a sputter target material.

The sputter target material thus obtained is melted in Ar gas (in a vacuum glove box replaced with Ar gas), poured into a stainless steel mold, cooled, solidified, and polished. A disk-shaped target having a diameter of about 100 mm and a thickness of about 5 mm may be formed and used.
A composite target may be formed by preparing _two targets of a composition of nTe and a target of Sb ₂ Te _3, and placing an InTe target formed in an appropriate size on the target of Sb ₂ Te ₃ . When a composite target is used, a target having an InTe composition and Sb ₂ Te _{3
X of} (InTe) _x (Sb ₂ Te ₃ ) _{1 -x} can be changed by changing the area ratio with respect to the target.

Further, a target having a small Zr (for example,
An inner diameter of 5 mmφ is formed, and this is sputtered on a 3-4 Sb ₂ Te ₃ target while rotating the substrate, whereby Zr can be doped.

The composition of the film formed by the sputtering method was analyzed by photoelectron spectroscopy (ESCA), and a small disk target of Sb or Te was prepared so as to have a target composition, and was prepared as described above. Sputtering is performed on the alloy type target, and correction is performed so that the target composition is obtained.

The same applies to the case of vacuum vapor deposition. Flash vapor deposition may be performed using a material synthesized in advance into a predetermined composition, or ternary vaporization of In, Sb, and Te may be used. When Zr is mixed, Z
r may be evaporated by an electron beam heating method.

Advantages of the embodiment The advantages of the embodiment described above are summarized as follows. The melting temperatures of the compounds InTe and Sb ₂ Te ₃ are 690 each.
° C and 616 ° C.
e) _x (Sb ₂ Te ₃ ) _1-x is 560 ° C. at x = 0.333,
It is as low as 565 ° C at x = 0.5. That is, thereby, recording can be performed with a laser power smaller than that of the binary compound, and there is an advantage that recording sensitivity is good.

When (In), (Sb), (Te or Te + Se) are taken at each vertex, the general formula (II) (InTe) _x (Sb ₂ Te _3-y Se _y ) is obtained on this triangular composition diagram.
In-Sb-Te-Se-based material having a composition within 2 atomic% from a straight line indicating a substance represented by _1-x (where x = 0.2 to 0.7 and y = 0 to 1.2) Has an extremely short erasing time of 0.2 μsec or less.

In-Sb-Te-Se in the above
A material having a composition obtained by adding 0.02 to 0.18 g of Zr, Mo, Ir or Pt per gram of the quaternary alloy material has a shorter erasing time of 0.1 μsec or less.

The thermal stability of the recording state (amorphous state) is determined by the crystallization temperature (Tx) and the activation energy E. In each of the above embodiments, Tx is equal to or higher than 120 ° C. = 2.0 eV or more, which is extremely rich in stability and the number of repetitions of recording / erasing is 10 ⁶ or more.

[0094]

As described in detail above, the rewritable phase-change type optical memory medium having the recording layer made of a material composed of a predetermined ratio of In, Sb, and M (Te or Te + Se) manufactured by the method of the present invention. A) High reflectivity in the recorded state and the erased state (20%
B) Recording and erasing can be repeated a large number of times (10 ⁶ times or more) c) Records can be stably stored over a long period of time (10 years or more) d) Recording erasing time It has an extremely excellent effect of being extremely short (less than 0.2 μsec).

If necessary, Zr, M
When a nucleating agent selected from o, Ir and Pt is contained,
The advantages of the above a), b), c) and d) become even more remarkable.

[Brief description of the drawings]

FIG. 1 is a triangular composition diagram showing a rewritable phase-change optical memory medium manufactured by a method according to an embodiment of the present invention.

FIG. 2 is a drawing showing annex-1.

FIG. 3 is a drawing showing a continuation of Attachment-1.

FIG. 4 is a drawing showing a continuation of Attachment-1.

FIG. 5 is a drawing showing a continuation of Attachment-1.

FIG. 6 is a drawing showing a continuation of Attachment-1.

FIG. 7 is a drawing showing the continuation of Attachment-1.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 7/00 G11B 7/24 511 7/24 511 B41M 5/26 X

Claims (6)

[Claims] 1. An In—Sb—Te-based substance or the I
I in which a part of Te of the n-Sb-Te-based material is replaced with Se
An n-Sb-Te-Se-based material having the general formula (In) _a (Sb) _b (M) _c ... (I) (wherein, a representing the ratio of In is 4 to 28 atomic%. B, which represents the ratio of Sb, is 17 to 44 atomic%; M is Te or Te + Se; c, which represents the ratio of M is 46 to 63 atomic%; when M = Te + Se, when Te = Se, Se to content
Has an atomic ratio of 0.35 atomic% or less. ) Is formed on a substrate, and then the thin film is irradiated with a laser pulse to melt the thin film.
The film is rapidly cooled to become amorphous, and then the amorphous film is irradiated with a laser pulse having a pulse width that is gradually increased to perform crystallization, thereby making the thin film a memory medium. A method of manufacturing a rewritable phase-change optical memory medium characterized by the above-mentioned. 2. An In—Sb—Te-based material or the I-based material
I in which a part of Te of the n-Sb-Te-based material is replaced with Se
An n-Sb-Te-Se-based material having the general formula (In) _a (Sb) _b (M) _c ... (I) (wherein, a representing the ratio of In is 4 to 28 atomic%. B, which represents the ratio of Sb, is 17 to 44 atomic%; M is Te or Te + Se; c, which represents the ratio of M is 46 to 63 atomic%; when M = Te + Se, when Te = Se, Se to content
Has an atomic ratio of 0.35 atomic% or less. ) Is formed on a substrate, and then the thin film is irradiated with a laser pulse to melt the thin film.
A writing method characterized by rapidly cooling to amorphize, and then subjecting the amorphized thin film to a memory medium by further performing a heat treatment in a vacuum to crystallize the thin film. A method for manufacturing a replaceable phase-change optical memory medium. 3. An In—Sb—Te-based substance or the I-type substance.
I in which a part of Te of the n-Sb-Te-based material is replaced with Se
An n-Sb-Te-Se-based material, where (In) and (S
b), (when taking a Te or Te + Se), on the diagram this triangular composition, the general formula _{(In Te) x (Sb 2} Te 3-y Se y) 1-x ... (II) ( where, x = 0.2 To 0.7, y = 0 to 1.2). A thin film made of a material having a composition within a composition region within 2 atomic% from a straight line indicating the material represented by the following formula is formed on a substrate. A rewritable phase-change optical memory medium characterized in that the film is rapidly cooled to become amorphous, and then the amorphous film is subjected to a crystallization process so that the thin film becomes a memory medium. Production method. 4. The method for manufacturing a rewritable phase-change optical memory medium according to claim 1, wherein the material constituting the thin film is 1 g of the material constituting the thin film.
A method of manufacturing a rewritable phase-change type optical memory medium, wherein 0.02 to 0.18 g of Zr, Mo, Ir or Pt is added to the medium. 5. An In—Sb—Te-based substance or the I
I in which a part of Te of the n-Sb-Te-based material is replaced with Se
An n-Sb-Te-Se-based material having the general formula (In) _a (Sb) _b (M) _c ... (I) (wherein, a representing the ratio of In is 4 to 28 atomic%. B, which represents the ratio of Sb, is 17 to 44 atomic%; M is Te or Te + Se; c, which represents the ratio of M is 46 to 63 atomic%; when M = Te + Se, when Te = Se, Se to content
Has an atomic ratio of 0.35 atomic% or less. ), A thin film containing 0.02-0.18 g of Zr, Mo, Ir or Pt per gram of the material is formed on a substrate, and then the thin film is melted and quenched to form an amorphous film. A method for manufacturing a rewritable phase-change optical memory medium, characterized in that the thin film is turned into a memory medium by applying a crystallization process to the amorphous thin film. 6. The method for manufacturing a rewritable phase-change optical memory medium according to claim 1, wherein a target having an InTe composition and a target having an Sb ₂ Te ₃ composition are used. A method for manufacturing a rewritable phase-change optical memory medium, characterized by changing the ratio of In, Sb, and Te in a thin film by changing the area ratio of two targets.