JPS6230087A - Optical information recording member - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Object of the Invention] The present invention relates to an optical information recording member for recording and reproducing optical information using light, heat, etc. It is an object of the present invention to provide an optical information recording member that has excellent repeat characteristics of recording and erasing, ti, and has little change in erasing rate over time, and is capable of recording and reproducing information signals at high speed and high density.

There are two types of optical discs that use laser light: write-once type, which allows recording and reproduction only once, and rewritable type, which allows recorded signals to be erased and used repeatedly.The present invention applies to the latter rewritable type. belong to The present inventors previously reported that Te-Tl
We proposed a method that uses changes in reflectance as a signal due to phase transition between the amorphous and crystalline states of IO2. In addition, Tg-T as a rewritable recording film using phase transition
Various additives (SW, □e, Bi, L, Pd, TL, Sg, etc.) are also added to +O□, and these are used to create recording films with high O/N and excellent moisture resistance. It is clear that it can be changed.

However, the above-mentioned recording film containing an oxide has the following drawbacks. For rewritable original discs, Tg
Erasing is performed in the crystalline state of -T-○, and recording is performed in the amorphous state.

This phase transition between crystalline and amorphous is performed by changing the conditions of gradual cooling and rapid cooling using laser light. That is, after heating with laser light, it becomes crystalline by slow cooling, and becomes amorphous by rapid cooling. Therefore, as recording and erasing are repeated, the recording film undergoes repeated phase transitions between a crystalline state and an amorphous state. In this case, if oxide exists in the recording film,
Due to the high viscosity of the membrane, the migration of chalcogenide is low, and segregation of membrane composition is likely to occur. Furthermore, since oxides have low thermal conductivity, a difference in temperature distribution occurs between the laser beam incident side and the opposite side, which also causes segregation of the film composition.

For the above reasons, recording films containing oxides have the disadvantage that their characteristics gradually change due to repeated recording and erasing. The object of the present invention is to eliminate this drawback and to improve the characteristics of conventional recording films made of chalcogen compounds, such as O/N, erasing rate, moisture resistance, and heat resistance.

[Structure of the Invention] The optical information recording member of the present invention comprises tellurium (
Contains Te), kermanium (G-), and iodine (SW) as main components, and the proportions of these elements are Te, i, 8
In the triangular coordinate diagram with μ as the apex of 10 D at%, the coordinate (αt=S) is A(Teos G'5B
"2), B (Teos"2 8%), O (Tg
6.01゜S"30), D (Tga2 GetB
S$o), 5 of W (Te52 G'411Su,)
The main component has a composition within the range surrounded by dots, and the amount of indium (In) added as a subcomponent is m, the amount of Te-Gg-SW system forming the main component is m, and the amount of indium (In) added as a subcomponent is m. When the amount of component In is rL (straw+L=100), the value is j ~ 40 cLl! It is characterized by having a recording film of %.

Attempts to use chalcogen compounds in recording films are old, and Tt-
Including Ge, A7. S.

There are examples in which properties have been improved by adding Si, Sg, Sh, Bi, etc. These replaceable recording films made of chalcogenides are generally characterized by poor stability against repeated recording and erasing. The reason for this is that Te%()g and other additive components cause phase separation of the recording film by repeating it several times, and the constituent components of the recording film are different at the initial stage and after the repetition. When phase transition is used in an erasable recording film, the unrecorded and erased state is usually crystalline, and in the case of The recording film is melted with laser light and made amorphous by rapid cooling, but current semiconductor lasers have limited power, so a recording film with a low melting point has high recording sensitivity. For this reason, the above-mentioned recording film made of chalcogenide has a composition with a melting point as low as possible, that is, a film composition with a high Tt content, in order to improve recording sensitivity. The fact that Tg is more abundant than other additive components means that phase separation is more likely to occur in the repeating characteristics. Therefore, how to fix the excess Te added to lower the melting point and make it difficult to move is the key to determining the repeatability and 0NR.
This means that it does not have a large effect on the temporal fluctuation of the 1 erasure rate.

The feature of the present invention is that L is added to the above-mentioned conventional composition Tt-Gt-8μ to fix excess 'ft. As a method of fixing excess Tg, it is possible to increase the saponity of ()(1, StL and make it stoichiometric GtTt and SμTg, but in the case of Gg, when the amount added is large, it becomes amorphous. The transition temperature from crystal to crystal is high), and large laser power is required for recording and erasing, making it impractical. Also S
In the case of w, if the composition is close to stoichiometric Su or Te, the crystalline state cannot be changed to a multistable amorphous state after vapor deposition. Therefore, it is advantageous to fix Ttf by adding L as in the present invention.

Next, the present invention will be explained in detail. In the present invention, Tt is a base material that exhibits a change in optical density between before and after recording in a state in which other elements are bonded. Ge controls the transition rate between amorphous and crystalline depending on the concentration ratio with Tg. That is, G
- In the region where the concentration of (Tg and (Jt only) is low,
Gg (50αt%) exists stably in an amorphous state, but as the concentration increases, the crystalline state becomes more stable, making it difficult to convert a crystalline state into an amorphous state. Since the Gt concentration in the present invention is less than 50αt, Gg contributes to increasing the amorphous nature of the film. The effect of Sw is similar to that of Qt, but the region in which BiL increases amorphousness with Te is narrow, and within the scope of the present invention, it rather promotes crystallization.

In other words, although Ge and U have similar effects on Te, T (depending on the concentration ratio between them, amorphousness increases) and crystallinity increases. As the concentration of Ge and Sw7 increases, the recording film becomes stable as a crystalline film, so that the transition from amorphous to crystalline becomes easy, but the reverse becomes difficult. Therefore, such a material is suitable as a write-once material (W10 material). However, even such a material can be used as an erasable disk if the laser power is strong and the recording film can be sufficiently melted. Currently, the semiconductor lasers that we can practically obtain have a wavelength of 85Qtm and a power of about 30%, with Tt, Gt
It is difficult to melt a composition close to stoichiometry (Tent, Tt8w) of , Sw. (Melting point is around SaO℃)T
The region that can be recorded and erased with t-Gg-Su is in a region where Tg is very high (80 αt% or more), but the composition of this region has a low transition temperature and is thermally unstable. T
Since g is excessive, by repeating Tt and Tg()g
Alternatively, TtBrt has the disadvantage that the recording film tends to undergo phase separation.

According to the present invention, this excess 7g is
It has the effect of stabilizing gIn-it.

When In is 7g and Tc is 50αt% or more in the above alloy system, the melting points are 696°C, 667°C, and 455°C, respectively, and even if L is added, the melting point of Te (451°C) does not increase.

Therefore, a recording film doped with T and n can be sufficiently melted with current semiconductor laser power. Furthermore, because excess Tc, which is thermally unstable, is bonded as Tex, a recording film that is thermally stable and stable for a long period of time without causing phase separation due to repeated recording and erasing can be created. Form. The amount of In added is the amount necessary to fix the remaining excess Tg combined with Gt and Sw, and in the region where the concentration of T is high, the concentration of I3 is also high.

[Explanation of Figure 1] Figure 1 shows the main components of the recording film of the present invention']
'g-()e-SIL concentration is expressed in a triangular coordinate diagram. In the figure, the coordinates of each point A, B, O, D, and Fi that define the composition range of the present invention are A (Te03
G's B"2), B (Te030h S"s
), C (Te68 G'2 s”yy ), D (Te
! 12 G'+a 13"so), E (Te52
G'4+1sq), and the recording film of the present invention has 1-Ge-8 within the range surrounded by this ABCDE.
The t+- system is the main component, and L is the subcomponent.
It is formed by adding 40αt%. Therefore, the structure of the recording film of the present invention can be expressed by the following general formula.

(Tt@3: Ge@I/ SIL@Z) m El Le However, x + y + z = 1 o o, m + Le = 100 If there is more Te than gland AB, the Qe concentration will inevitably decrease and amorphization will occur. It becomes difficult. Also, because the atStt concentration is low,
The transition temperature from amorphous to crystalline is also low. From iEo, G
When e is low, the transition temperature is low, as in the case where there are many lines AB and υTC. Also, the tendency for crystalline to amorphous transformation is better than with more Tt, but
From a practical point of view, a sufficient phase transition from crystal to amorphous cannot be obtained. If the Sυ concentration is higher than line CD, 6 m
Since the addition of promotes crystallization, it becomes difficult to make it amorphous.

Furthermore, the transition temperature from amorphous to crystalline is low, and thermal stability is poor. When Tg is less than the lines D and E, it is difficult to make this region amorphous because Te, Qg, and 13LL form stable GtTe, P; μTg, which is close to the stoichiometric crystal structure. Furthermore, since there is almost no excess Tt in this region, the concentration of added phosphor is also low. That is, the effect of adding In is also small. Therefore, the melting point of the film is high in this region, making it difficult to make it amorphous. In a region where 3TL is less than line KA, crystallization is difficult because it is stable as an amorphous state. However, this tendency is controlled by the ratio of Te and Gt on the EA line; the more Te there is, the easier crystallization is, and when the T concentration is around 70αt%, crystallization is the most difficult. At around 50 αt%, crystallization becomes easy again. The reason is that Te and Gt form a more stable amorphous compound (Jg'ft), and when the 'fe concentration is around 70 cm, it is difficult to crystallize it as a whole.

For the reasons stated above, T which constitutes the main component of the present invention
The g-Gt-Bu system is A and B in FIG.

0 and DlFi within the range surrounded by five points. That is, if 1 to 40 αt% of L is added as a subcomponent to Tt −Gg−8tb in this region, information can be practically recorded and erased by utilizing the reversibility between crystalline and amorphous states.

[Explanation of FIG. 2] Similar to FIG. 1, FIG. 2 shows the concentration of the main component g-GLL-flu of the recording film of the present invention in a hexagonal coordinate diagram. The area surrounded by the four points FSG, H, and I is the area of claim (2), in which 10 to 35 αt% of L is added as a sub-component. Also, H, J,
The portion surrounded by the five points L and M is within the scope of the claim (5).
), and 1 to 15 αt% of L is added as a subcomponent. As shown in Figure 4, each point F to M is within the area defined by A, B, O, D, and E within the scope (1) of patent claim 2, and the coordinates of each point are as follows. This is Notooshi.

F C'feat Gt5 5TJ-q), G(T
eoz G'3 8%)H(Tees G's 5I
L29), Engineering (Te?4 G'2s S”3) J
(τ'7n G'+o S"vo), K (Team
"to S"t )L (TI'52 G'45
6 y, ), M (Te52 G'+o S”2G
) FGI (The transition temperature from amorphous to crystalline in the region surrounded by the four points of I is within 90 to 16oC, and the 5 points of HJKLM
Transition temperature of the area surrounded by dots (approximately 150 to 220℃)
lower than. The addition of X has the effect of increasing the crystal dislocation source I by 10 to 30°C compared to the case of only Te-Gg-8n. Therefore, the addition of In has the effect of increasing the transition temperature indicating thermal stability and the advantage of facilitating the formation of an amorphous film without significantly increasing the melting point of the recording film.

Since the region surrounded by the five points of HJKLM has less excess Te, the effect of adding In is smaller than in the case of FGH processing.

However, it is easier to become amorphous than the Tt-Qg-Su system in which L is not added. The H,TKLM region has a high transition temperature and is thermally stable, and its composition is close to the stoichiometry of GtTe and BuTe, so crystallization is easy and amorphous is difficult. If so, amorphization becomes easy. The area surrounded by points I and TK is a region where stable amorphous GIT exists, and crystallization is difficult. For the reasons described above, the optimal composition of the main component Tt-Qg-Su system and the subcomponent In of the present invention is limited.

[Explanation of FIG. 3] FIG. 5 shows a cross section of an optical disk using the recording film of the present invention. 1.5 is a substrate made of a transparent material such as polycarbonate, acrylic resin, glass, polynisdel, etc.; 2.4 is a protective layer made of various oxides, sulfides, carbides, etc.; and 3 is the recording film of the present invention. . The protective layer 2.4 is formed on the substrate 1.4 by repeated recording and erasing of the recording film 3.
In addition to preventing thermal deterioration of the recording film 5, it also acts as a moisture-proofing agent for the recording film 6. The recording film 6 is formed by vapor deposition, sputtering, or the like. The thickness of the recording film 3 is set to a value that matches the optical characteristics of the protective layer 2.4 (allowing a large difference in reflectance between the recorded and unrecorded areas).

[Example 1] Using a four-source electron beam evaporator, T1
．． G4, 3W, and L were deposited from their respective sources.

The substrate is a glass plate with a diameter of ψ8, and the degree of vacuum is 1X 10 To
rr, the rotation speed was 1i150 rpm, and the film thickness was 1
000 people. The deposition rate from each source was varied to adjust the ratio of the number of Tt, Gt, Su, and In atoms in the recording film. The compositions in Table 1 are values calculated from this vapor deposition rate.

Note that typical compositions are measured using an X-ray microanalyzer (X)i
! When Ai was measured, the quantitative results were different from the preparation values, similar to y. Test specimens A to M and 1 to 16 prepared by the above manufacturing method were evaluated for transition temperature, blackening properties, and whitening properties. The results are shown in Table 1. FIG. 4 shows the positions of test pieces A to M and 1 to 16 in a triangular coordinate diagram.

(Transition temperature) The transition temperature is the temperature at which a film that is in an amorphous state immediately after vapor deposition starts to change to a crystalline state due to heat. For this measurement, a device for measuring membrane transmittance was used, and when the temperature of the test piece was raised by a heater at a heating rate of 1 ψtC, the temperature at which the transmittance started to decrease was defined as the transition temperature. A high transition temperature means that the recording film is thermally stable.

(Blackening properties and whitening properties) Blackening properties indicate the rate of transition from amorphous to crystalline, and whitening properties indicate the rate of transition from crystalline to amorphous. Measurements were carried out by focusing a laser beam onto the recording film on the test piece using a lens, and moving the test piece up and down and left and right. The laser beam spot is 45 x 0.4 pm, and the pulse width is 400n-
y.

The power density was 1Q, 6 groans 20/wavelength was 900M. The blackening characteristics are determined by observing the speed of transformation (from amorphous to crystalline) when the specimen is moved relatively slowly. Those that are sufficiently large are marked as ◎. × indicates that the image does not turn black even when moved slowly, or that the contrast ratio is small. ○ and Δ are located between ◎ and ×.

In this qualitative expression, the practical blackness is 0.
That's all. The whitening property quickly removes blackened specimens.
Move it to create a rapid cooling state and whiten it (crystalline → amorphous). A whitening state of ◎ indicates that whitening occurs even if the moving speed is relatively slow, and the contrast ratio between the amorphous portion and the crystalline portion is large, and × indicates that there is no whitening at all. O and Δ are located between ◎ and ×.

According to the above expression, if both the blackening property and the whitening property are excellent, ◎ and ◎ will be obtained, but in reality, it is impossible and desirable for both to be ◎ at the same movement speed. Preferably, the material has somewhat excellent blackening properties, such as ◎, ◎, ◎, ∆. 1st
As shown in the table, compositions A-M and 1-16 within the area of the present invention surrounded by the five points of ABODE in FIG. It is possible to add and erase.

Table 1 (1) Table 1 (2) [Example 2] In this example, from the area surrounded by the FGH work in Figure 2, Te8°G'to S''10 (Point 4 in Figure 4) , T'60 G from the area surrounded by HJKLM
Select '2' 5th - 3 (point 12 in Figure 4) respectively,
By the same manufacturing method and evaluation method as in Example 1, Te-ae
When L was added to the -sμ system, the effect of In concentration on the characteristics was tested. The results are shown in Table 2, F
In the GH engineering region, the In concentration ranges from 10αt% to 35αt%.
Good properties are shown between t % and In in the HJKIJM range, it is possible to use In with an a degree of 1 to 15 αt %. Plate 24 (P (5 cLt% or less) is outside the scope of the present invention, does not whiten, and does not become a rewritable recording film.

Although it is possible to blacken A30 with blackening physical properties of X to Δ, it is difficult to use practically.

$ 2 Table [Characteristics tester using optical disks 1] A polycarbonate resin plate with a thickness of 12 m and a diameter of 200 m is used as the substrate 1 shown in Fig. 3, and a heat-resistant layer of 2 S is evaporated to a thickness of 900 X as the protective layer 2. On top of that, a recording film 5 with a thickness of 100L is placed as shown in Example 1.
Zn was deposited using the method of
The protective layer 4 of No. 8 was deposited on the substrate 5 in close contact with the substrate 5, and the recording film 3 was made of the films 21 and 26 shown in Table 2.
Two types of optical discs were created.

For these two types of optical discs, the recording power and erasing power are 8rrLω and 15mω, and the recording beam is ψ1.
μrn (half width), erasure laser beam length is approximately 1s tt
Recording and erasing tests were conducted in a whitened state and a blackened state, with m (half width).

The recording frequency is ZMHz, and the disk peripheral speed is 57n.
/j. The results are as follows.

(1) The C/N of the Y21 disk is ss bB, the erasure rate is -53 dB, and the O/N of the A26 disk is 49 d.
B.? The acid d company was -46 dB. (2) After repeating recording and erasing 100,000 times, the reduction in ○β was -5 dB for A21 disks, -2 dB for 1626 disks, and the reduction in erasure rate was 1 dB and 0.5 dB, respectively. (3
) 80°C, fβ exposed for 1 month under 6'04RI-11D
After this, the O/H of the Ya21 disk decreased by -1 dB, and the erasure rate decreased by 1 dB.

[Characteristics Test with Optical Disc 42] The properties of the 421 optical disc were tested using GgO2 and SIA as the heat-resistant protective layer. The thickness of the protective layer (2) is a oo
i. The thickness of the protective layer (4) is 1900λ. The rest is the same as in the case of characteristic test plate 1. The result is (1) O
/N was 52 dB for G-4 and 50 dB for Sia. Also, the erasure rate is -47
dB and -48 clB. (2) Life test (1
Regarding the characteristic deterioration after being left in the evening moon, the deterioration of 0ha in the case of Goo was -MB, and the deterioration in the case of stc was -αBdB.

[Characteristics Test AS Using Optical Disc] An optical disc using the A5 recording film of Example 1 was prepared using the same substrate and method as in Characteristics Test 1. In addition, the heat-resistant protective layer 2 is 860s,
The recording layer 3 is 300 people, and the protective layer 4 is 1950X. The c/N of this optical disc is 54 dB, and the erasure rate is -52 d.
B, c/N after 100,000 recordings and deletions
The reduction was -2 dB.

[Effects of the Invention] As described above, the optical information recording member of the present invention has been improved through numerous experiments by adding L to the T$-Qg-Su system and repeating recording and erasing. By determining the effective blending range of the ingredients, we have made it possible to achieve sufficient blackening (digestion) and whitening (recording) with current semiconductor laser power, and we have also made it possible to achieve sufficient blackening (digestion) and whitening (recording) with the current semiconductor laser power. It has an excellent effect of eliminating defects.

[Brief explanation of drawings]

Figure 1.2 Pentagonal coordinate diagram showing the composition of the main components of the recording film of the optical information recording member of the present invention.2.3 Showing the composition of the main components of the recording film of claims (2) and (6). Angular coordinate diagram Figure 3: Cross-sectional view of the optical information recording member of the present invention Figure 4: A drawing showing the positions of test pieces A-M and 1 to 16 in the triangular coordinate diagram of Example 1 of the present invention (No change in content) 1, 2, 3, 4 Procedures Amendment book (method) % formula % t Indication of the case 1985 Registration Permit No. 169608 Z Name of the invention Optical information recording member 5. Relationship with the case of the person making the amendment Applicant 571 1006 Kadoma, Kadoma City, Osaka Prefecture @ 582 Ji
Matsushita Electric Industrial Co., Ltd. Tun Agent

Claims (2)

[Claims] (1) Contains tellurium (Te), germanium (Ge), and tin (Su) as main components, and the ratio of these elements is the coordinate (at %) is A(Te_9_
3Ge_3Su_2), B(Te_9_3Ge_2Su
_3), C(Te_6_8Ge_2Su_3_0), D
(Te_5_2Ge_1_3Su_3_0), E(Te
_5_2Ge_4_6Su_2) The main component has a composition within the range surrounded by the five points, and the amount of indium (In) added as a subcomponent is the amount of the Te-Ge-Su system forming the main component. m, the amount of subcomponent In is n
(m+n=100), the value of n is 1 to 40at
An optical information recording member characterized by having a recording film of %. (2) The coordinates of Te, Ge, and Su that constitute the main components are F (Te_9_2Ge_5Su_3) in the triangular coordinate diagram.
, G(Te_9_2Ge_3Su_3), H(Te_6
_8Ge_3Su_2_9), I(Te_7_4Ge_
Claim (1) characterized in that the amount of In added as the subcomponent is within the range surrounded by the four points 2_3Su_3), and the value of n is 10 to 35 at%. Optical information recording member (3) The coordinates of Te, Ge, and Su constituting the main components are H(T) in the triangular coordinate diagram.
e_6_8Ge_3Su_2_9), J(Te_7_0
Ge_1_0Su_2_0), K(Te_6_8Ge_
2_9Su_3), L(Te_5_2, Ge_4_5S
u_3) M(Te_5_2Ge_1_9Su_2_9)
Optical information according to claim (1), characterized in that the amount of In added as the subcomponent is within a range surrounded by five points, and the value of 1 is 1 to 15 at%. recording member