JPH043574B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an optical information recording member capable of recording and reproducing optical information at high speed and with high density using light, heat, etc. Conventional technology Recording of high-density information using laser beams,
Techniques for performing regeneration are known. Te and TeO ₂ are deposited on the substrate as a recording medium used for such recording and reproduction.
There is a thin film mainly composed of TeOx ₁ (0 < x ₁ < 2), which is a mixture of
Publication No. 46318, Japanese Patent Application Laid-open No. 1983-46318, Japanese Patent Application Publication No. 1983
46319, U.S. Pat. No. 3,971,874). The additive components include PdOx ₅ (0< _x5 <1), SbOx ₆ (0
< x ₆ < 1.5), VOx ₇ ((0 < x ₇ < 2.5), etc. are used. Such a recording medium can obtain a large change in transmittance when irradiated with a light beam for reproduction. However, When trying to downsize and simplify recording and playback equipment, there is a limit to the output of the laser light source that can be used, so it is recommended to record using a compact He-Ne laser oscillation device, semiconductor laser oscillation device, etc. with an output of less than 20mW. , for regeneration, conventional TeOx (0<x
A recording medium provided with a thin film containing <2) as a main component has insufficient sensitivity. Furthermore, when information is reproduced by changing the amount of reflected light, a sufficient amount of change cannot be obtained. Next, to compensate for the above drawbacks, TeOx (0
<x<2), there is an attempt to lower the threshold temperature of state change by applying an additive material with a low melting point, for example, there is a method of adding TlOx (0<x<1.5) (Tl ₂ O melting point 300° C.). On the other hand, there is a method of increasing the refractive index of the medium in order to increase the change in optical properties accompanying state changes, and for this reason, attempts have been made to use dopant materials with high ionic polarizability and high density. For example, BiOx ₂ , InOx ₂ (0<x ₂ <1.5), etc. (Japanese Patent Application No. 53-109002, Japanese Patent Application No. 1983-71506). These methods have made it possible for recording media containing TeOx as a main component to be recorded by a semiconductor laser and reproduced by changing the amount of reflected light. Problems that the invention aims to solve However, with the advancement of the information society, there is a need for faster information transmission than ever before, and it has become necessary to improve recording and playback speeds more than ever before. There is. Conventional optical information recording members using TeOx thin films made of TeO ₂ and Te have had a problem in that it takes a certain amount of time for the reproduced signal to obtain a sufficient amplitude or CN ratio after recording. In other words, there is a change in the quality of the reproduced signal immediately after recording and after a certain period of time has elapsed. In practical terms, this means that the time required for recording is long, that is, the recording speed is low. The present invention is a mixture of traditional _TeO2 and Te
Improved optical recording thin film mainly composed of TeOx,
The object of the present invention is to provide an optical information recording member that does not have the above-mentioned phenomenon and has a recording speed that is significantly improved compared to the conventional one, while retaining the advantages of the TeOx thin film, such as good moisture resistance. Means for Solving the Problems The optical information recording member of the present invention has an optical recording film formed on a substrate that is made of at least four materials: tellurium (Te), oxygen (O), palladium (Pd), and gold (Au).
Composed of elements, Pd and Au for the sum of four elements
The sum of the contents is 5 to 40 atm %, and the oxygen content is 20 to 60 atm %, and at least part of the oxygen is contained as TeO ₂ , an oxide of Te. Effect Pd and Au are present in TeOx thin films during recording.
It promotes the state change of Te, that is, it is thought to act like a crystal nucleus.
This achieves faster recording. When a TeOx thin film, which is a mixture of TeO ₂ and Te, is irradiated with high-density light such as laser light, its optical constants change and it appears black. This change is used to optically record and reproduce information, but this change occurs through a process of light irradiation, absorption, and temperature rise, which results in a change in the state of the Te particles in the film, that is, a change in the crystal grain size. It is thought that this is due to optical changes caused by growth. Therefore, in order to increase the recording speed, it is considered that a major factor is how quickly this state change can be completed. By the way, the problem with conventional TeOx-based thin films is that when Te particles undergo a state change during recording,
Due to the TeO ₂ barrier, it took some time for the structure to relax to a stable crystalline state. Although such a recording member poses no problem when recording images or the like as information, it is undesirable when used as a computer disk that requires high-speed response due to equipment design limitations. The present invention was made in view of the current situation, and it is possible to add Pd and Au to TeOx, which is a mixture of Te and TeO ₂ .
By using a thin film with a basic composition of TeOx added as the recording layer and controlling the ratio of the number of Te, O, Pd, and Au atoms in the film, the recording time is much shorter than that of conventional TeOx-based recording thin films. In other words, it is possible to provide an optical information recording member that allows recording to be completed at a much higher speed. Conventionally, there are examples of improving optical recording characteristics by adding a third substance to Te or a mixture of Te and TeO ₂ . However, they are limited to Ge, Sn,
Elements with relatively strong covalent bonds, such as Pd, Si, Sb, and Se, were limited to substances that easily form a glassy state with Te or a mixture of Te and TeO ₂ . The present invention uses elements with strong metal bonding properties such as Au, Ag, Cu, and Pd, especially Pd and Au.
The effect of adding Pd and Au is specifically exhibited only when the selected materials fall within the scope of the present invention. The roles of Pd and Au in the present invention are inferred as follows. When recording in a TeOx thin film, Pd and Au
It promotes the state change of Te, and is thought to act like a crystal nucleus, and it is thought that a small amount can produce a large effect in order to complete recording at high speed. Furthermore, the fact that the state change of Te is completed at a high speed during recording means that, for example, when the laser beam irradiation area is considered to soften or melt, the state change will be completed while the viscosity of the film is small. , Therefore, it is assumed that Te crystal particles with more advanced crystallinity are generated.
As a result, it is thought that a larger change in the reflectance of the reproduction light can be obtained and a higher CN ratio can be obtained. Furthermore, by adding Pd and Au to TeOx, the light absorption efficiency increases. As a result, writing can be performed even with a lower power laser beam, and high sensitivity can be expected. Furthermore, since Pd and Au do not undergo oxidation due to their nature, they do not seem to impair the excellent moisture resistance of the known TeOx film. The present invention is composed of Te, O, Pd, and Au as essential components, but in order to improve the optical properties and heat resistance of the film, Ge, Sn, Al, Cu, Ag, Au,
Se, Bi, In, Pb, Si, Pt, Sb, As, V, Cr,
It is optional to include one or more elements selected from Co and Ni. The optical information recording member of the present invention can be used not only as a recording material for recording and reproducing only, but also as a recording material in which information can be rewritten. In this case, at least one of the above-mentioned elements is added, It is possible to improve the erasing characteristics. Next, the amounts of Pd and Au added in the present invention will be described. The sum of the amounts of Pd and Au added in the present invention is Te,
It is 5 to 40 atm% of the total amount of O, Pd, and Au. Pd and Au are in the film and the TeOx
It is believed that it exists in an amorphous state as a mixture of PdTe alloy and AuTe alloy. When this is heated with a laser etc., it becomes amorphous.
Mixtures of PdTe and AuTe alloys become crystalline and produce optical changes. The mixture of PdTe alloy and AuTe alloy in the film
They do not necessarily have to have stoichiometric compositions.
It is sufficient that it exists in an alloy composition of PdTe-Te and AuTe-Te, and it is thought that the role of the mixture of PdTe alloy and AuTe alloy is to serve as crystal nuclei and promote the overall crystallization rate. Therefore, it is sufficient that the sum of the contents of Pd and Au is less than that of Te. However, if the sum of the amounts of Pd and Au added is less than 5 atm%, the number of crystal nuclei of the mixture of PdTe alloy and AuTe alloy in the film will decrease, and high-speed crystallization cannot be expected. As the amount of Pd and Au added increases, light absorption efficiency improves and recording sensitivity becomes better.
If more than 40 atm% is added, the relative amount of Te in the film will decrease, resulting in a decrease in the change in the amount of reflected light before and after recording. Therefore, the sum of the amounts of Pd and Au added is 5~
Must be in the range of 40 atm%. Next, the oxygen content will be described. In the composition of the present invention, most of the oxygen is in the film.
It exists in the form of Te and TeO ₂ . in the membrane
The amount of TeO ₂ present is important in determining the moisture resistance of the film, and the greater the amount of TeO ₂ , the better the moisture resistance.
Therefore, the higher the oxygen content in the film, the better it is, but if it is too high, the PdTe alloy and
As the content of the AuTe alloy mixture becomes relatively small, the light absorption efficiency of the film decreases and the sensitivity decreases, and at the same time, the amount of change in reflectance before and after recording becomes small, making it impossible to obtain a high CN ratio. Put it away. In the present invention, the oxygen content is Te, O,
Although it is 20 to 60 atm% of the total amount of Pd and Au,
If it is less than 20 atm%, the moisture resistance will be poor, and if it exceeds 60 atm%, the recording sensitivity will decrease. Te, O, which are essential components within the scope of the present invention,
A particularly preferable composition for Pd and Au is Pd and Au.
The sum of the Au content is 8 to 35 atm%, and the oxygen content is 8 to 35 atm%.
It is 30 to 55 atm% (detailed in Example 1). Next, the present invention will be explained in detail with reference to the drawings. FIG. 1 is a sectional view of an optical information recording member according to the present invention. 1 is a substrate made of metal, such as aluminum,
Copper etc., glass such as quartz, pirate glass, soda glass etc., or resin such as ABS resin, etc.
Polystyrene, acrylic, polycarbonate, vinyl chloride, etc. can be used, and as the transparent film, acetate, Teflon, polyester, etc. can be used. Among them,
When polycarbonate, acrylic plates, etc. are used, they have excellent transparency and are effective in optically reproducing the formed signal image. A recording thin film 2 is formed on the substrate 1 by vapor deposition, sputtering, or the like. For vapor deposition, there are two methods: heating from another part, such as resistance heating, and direct heating of the sample, such as electron beam, both of which can be used. However, the electron beam method is superior in terms of controllability of vapor deposition, mass productivity, etc. Below, using the electron beam method, 4 of Te, O, Pd, and Au were
A method for manufacturing thin films made of elements will be described. A mixture of Te, O, Pd, and Au is formed on the substrate, but in reality, a mixture of Te, TeO ₂ , Pd, and Au is formed, so a vapor deposition machine capable of four-source vapor deposition is required. TeO ₂ , Te, Pd, and Au are evaporated from their respective sources using . In addition, when using a three-source source, Pd is evaporated from one evaporation source, Au is evaporated from another evaporation source, and TeO ₂ and TeO ₂ are partially reduced from another evaporation source. Metal powders, such as Al, Cu, Fe,
TeO ₂ and Te are simultaneously vapor-deposited using a mixture of Cr and the like and heat-treated at a predetermined temperature to form a mixture of TeO ₂ , Te, Pd, and Au on the substrate. In addition, when using a two-source source, a source for evaporating TeO ₂ and Te when using the three-source source,
It is also possible to deposit using a mixed source of Pd and Au. It is also possible to deposit from a mixture of these from a single source. Examples Examples of the present invention will be described in detail below. Example 1 Using an electron beam evaporator capable of four-source evaporation,
TeO ₂ , Te, Pd, and Au from their respective sources,
A prototype optical disk was fabricated by vapor deposition on an acrylic resin substrate with a thickness of 1.1 mm and a diameter of 200 mm that rotates at 150 rpm. Vapor deposition was performed at a vacuum level of 1×10 ⁻⁵ Torr or less, and the thickness of the thin film was 1200 Å. The deposition rate from each source was varied to adjust the ratio of the number of Te, O, Pd, and Au atoms in the recording thin film. The results of elemental analysis by Auger electron spectroscopy (hereinafter referred to as AES) of various optical discs created using the above method and the position 75 mm from the center of the optical disc rotating at 1800 rpm are shown so that the CN ratio is the highest when recording is completed. The CN ratio of a signal with a single frequency of 5 MHz written with a laser power of was completed) CN at the time of elapsed time
The ratio and the results of the moisture resistance test are shown in Table 1. The data for disks No. 18, 19, and 20 in Table 1 are data for conventional TeOx containing Pd and Au, and are also listed for comparison.

【table】

[Table] The recording/reproducing test was conducted using the system shown in FIG. 2. Wavelength 830n emitted from photoguide laser 14
The light of m becomes pseudo-parallel light 3 by the first lens 15, is shaped into a round shape by the second lens 4, becomes parallel light again by the third lens 5, and has its optical axis converted by the mirror 6. The light is focused by a fourth lens 7 via a half mirror 11 onto a spot 9 having a wavelength limit of about 0.8 μm on the optical disk. The recording film on the optical disk 8 irradiated by this circular spot 9 is
Recording is performed through blackening transformation due to a change in the state of Te. Here, the semiconductor laser can be modulated to record information signals on the optical disk. The signal is detected using the reflected light 1 from the optical disk surface 8.
0 through the half mirror 11, and the lens 12
The photosensitive diode 13 was used through the photosensitive diode 13. From 33msec after laser beam irradiation in Table 1
If the CN ratio is larger at 2 min, it is thought that the growth of Te crystal grains is still progressing in the thin film after 33 msec, indicating that recording has not yet been completed. This shows that recording is completed after 33 msec for those with the same CN ratio. In addition, the moisture resistance test was carried out by depositing a recording thin film on a glass substrate (18 x 18 x 0.2 mm) as a sample for the moisture resistance test at the time of manufacturing the optical disk, and leaving it at 50°C and 90% RH. For the moisture resistance evaluation in Table 1, ○ indicates that no change was observed when observed under a microscope on the 10th day, △ indicates that some change was observed, and black pattern was observed due to advanced crystallization. Those in which the transmittance increased due to oxidation of Te in the film were marked as ×. Conventional TeOx (Dix No. 18, 19 and 20) that does not contain Pd and Au as shown in Table 1
In this case, the CN ratio changed significantly after 2 minutes had elapsed compared to when 33 msec had elapsed after laser beam irradiation, indicating that recording had not been completed at 33 msec. On the other hand, for those containing Pd and Au, there is no change in the CN ratio during this period, or the change in the CN ratio is small, within 3 dB.
It can be seen that the recording speed has improved. As is clear from Table 1, the CN after recording is complete.
ratio is 50dB or more and 33msec after laser beam irradiation
has been recorded and has good moisture resistance.
The composition of the Te-O-Pd-Au thin film (over △ in the overall evaluation) is that the sum of Pd and Au content is 5 to 5.
40atm% and oxygen is 20-60atm%. It can be seen that a more preferable composition (○ in overall evaluation) is a sum of Pd and Au of 8 to 35 atm% and an O of 30 to 55 atm%. Additionally, Pd with an oxygen content of 20-60 atm%
Table 2 also shows the experimental results for cases in which only Au is contained and in cases where only Au is contained. As shown in Table 2
When Pd is 4atm%, from 33msec after laser beam irradiation
A slight change in the CN ratio was observed by 2 min, and Pd
At 46 atm%, the absolute value of the CN ratio is less than 50 dB, which is insufficient. Sufficient characteristics were obtained when the Pd content was 5 to 40 atm%. Similarly, in the case of Au, sufficient characteristics were obtained in the range of 4 to 18 atm%. From the above results, the sum of Pd and Au content is 5~
It was found that sufficient characteristics could be obtained at 40 atm%.

[Table] Example 2 Using an electron beam evaporator capable of evaporating with three sources, an optical disk was created by evaporating Pd from one source, Au from another source, and Te and TeO ₂ from another source. Created. Here we will explain a method for simultaneously depositing Te and TeO ₂ from one source. First, TeO ₂ 85wt% as a starting material,
Mix 15wt% Al with a small amount of alcohol,
25g of the powder was placed on a quartz boat and fired in an electric furnace at 700℃ for 2 hours while flowing _N2 gas.
A part of TeO ₂ was reduced, and the fired product was crushed and pressed to obtain a molded body (pellet), which was then vapor deposited. By the above method, the deposition rate was 1 Å/S for Pd and 1 Å/S for Au on the same acrylic resin substrate as in Example 1.
0.5 Å/S, (Te+TeO ₂ ) was deposited at 20 Å/S,
An optical disk was fabricated by forming a recording thin film of 1200 Å. As a result of elemental analysis of the above recording thin film by AES,
Te: 57 atm%, O: 28 atm%, Pd: 10 atm%,
Au: 5 atm%. In addition, when the same recording/reproducing test and moisture resistance test as in Example 1 were conducted,
The CN ratio at 33 msec and 2 min after laser beam irradiation was both 62 dB, confirming that recording was completed at high speed, and the moisture resistance evaluation was ○. Example 3 Using an electron beam evaporator capable of vapor deposition using two sources, an optical disk was fabricated by vapor-depositing Pd and Au from one source and Te and TeO ₂ from the other source. The method for simultaneously depositing Te and TeO ₂ from one source is the same as that described in Example 2. The method for simultaneously depositing Pd and Au was to put Pd and Au raw materials in an electron beam hearth, heat them with an electron beam, melt them, and use them as an alloy.
By the above method, an alloy containing Pd and Au mixed at a ratio of 3:1 was deposited on the same acrylic resin substrate as in Example 1 at a deposition rate of 1.5 Å/S and (Te+TeO ₂ ) of 20
A recording thin film of 1200 Å was formed by vapor deposition at Å/S, and an optical disk was manufactured. As a result of elemental analysis of the above recording thin film by AES,
Te: 55 atm%, O: 38 atm%, Pd: 12 atm%,
Au: 5 atm%. When the same recording/reproducing test and moisture resistance test as in Example 1 were conducted, the CN ratio at 33 msec and 2 min after laser beam irradiation was both
It was confirmed that recording was completed at a high speed of 55 dB, and the moisture resistance evaluation was ○. Example 4 Depositing Te-O-Pd- from only one source
To obtain the Au thin film, TeO ₂ as a starting material;
60wt%, Al: 10wt%, Pd: 20wt%, Au: 10wt
% with a small amount of alcohol, powder 25g
was placed on a quartz boat and heated with _N2 at 700℃ using an electric furnace.
A part of TeO ₂ was removed by firing for 2 hours while flowing gas.
After reduction with Al, the fired product was crushed and pressed to obtain pellets, which were then vapor deposited. By the above method, deposition was performed on the same acrylic resin substrate as in Example 1 at a deposition rate of 20 Å/S to form a recording thin film of 1200 Å, thereby producing an optical disk. Results of elemental analysis of the above recording thin film using AES
Te: 57 atm%, O: 36 atm%, Pd: 4 atm%,
Au: 3 atm%. In addition, when the same recording/reproducing test and moisture resistance test as in Example 1 were conducted,
CN at 33msec and 2min after laser beam irradiation are both
It was confirmed that recording was completed at a high speed of 60 dB, and the moisture resistance evaluation was ○. Effects of the Invention The optical information recording member according to the present invention has at least
It consists of Te, O, Pd, and Au, and the sum of the contents of Pd and Au is 5 to 40 atm% (preferably 8 to 35 atm%).
%) and with an oxygen content in the range of 20 to 60 atm% (preferably 30 to 55 atm%) as an optical recording film.
The recording speed is significantly higher than that of an optical information recording member having a thin film, and it also has excellent moisture resistance.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing an example of an optical information recording member according to the present invention, and FIG. 2 is a schematic diagram of an apparatus for recording and reproducing information signals on an optical disc according to the present invention. 1...Substrate, 2...Recording thin film.

Claims (1)

[Claims] 1 Consisting of at least tellurium (Te), oxygen (O), palladium (Pd), and gold (Au), the sum of the contents of Pd and Au relative to the sum of Te, O, Pd, and Au. is 5 to 40 atm%, and the oxygen content is 20
An optical information recording member characterized in that it has an optical recording thin film in which a portion of oxygen is contained at least as an oxide of _TeO2 at ~60 atm%. 2. The optical information recording member according to claim 1, wherein the content of oxygen is 30 to 55 atm%.