JP2000187892A - SiO2 film, phase change type optical disk medium and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SiO ₂ film having suitable characteristics as a protective film 2 for a phase change type optical disk medium, and a protective film 2 for a phase change type optical disk medium manufactured using this SiO ₂ film. Further, the present invention provides a phase change type optical disk medium which is manufactured using the protective film and can obtain stable signal characteristics even when performing a recording and reproducing operation many times repeatedly, and a manufacturing method excellent in productivity thereof. SOLUTION: The SiO ₂ film is formed by sputtering using a Si target and using a mixed gas of oxygen gas and argon gas or a mixed gas of oxygen gas, argon gas and hydrogen gas as a sputtering atmosphere gas. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a SiO ₂ film, a protective film for a phase change type optical disk medium, and a phase change type optical disk medium, and a method for manufacturing these. The present invention relates to a SiO ₂ film suitable as a protective film for a phase-change optical disc in which the structural change between a crystal and an amorphous phase and the optical properties change by heating / cooling, and a method for producing the same.

[0002]

2. Description of the Related Art At present, an optical information recording system using a laser beam is capable of non-contact and high-speed access to a large amount of information, and has been put to practical use as a large-capacity memory in various places. Optical information recording / reproducing media using the optical information recording / reproducing method include a read-only type known as a compact disk or a laser disk, a write-once type that can be recorded by the user, and a recording / reproducing method that can be repeatedly performed by the user. Classified as rewritable. Write-once and rewritable optical information recording / reproducing media are being used as external memories of computers, documents, and image files.

The rewritable optical information recording / reproducing medium includes a phase-change optical disk utilizing a phase change of a recording film and a magneto-optical disk utilizing a change in the magnetization direction of a perpendicular magnetization film. Of these, the phase-change optical disk does not require an external magnetic field when recording information, unlike a magneto-optical disk, and can easily overwrite, ie, overwrite, recorded information. It is expected to become the mainstream of information recording / reproducing media.

Conventionally, a rewritable phase-change optical disk utilizing a phase change between a crystal and an amorphous of a recording film by irradiating a laser beam has been known. In this phase-change optical disk, recording is performed by irradiating a high-power laser beam to the recording film to locally raise the temperature of the recording film, thereby causing a phase change between the crystal and the amorphous of the recording film. Do. Reproduction of recorded information is performed by irradiating a laser beam having a relatively low power as compared with recording, and detecting a change in an optical constant of the information recording unit as a reflected light intensity difference.

For a recording film of a phase-change optical disk, chalcogenide-based materials such as GeSbTe-based, InSbTe-based, and AgInSbTe-based materials are used. Each of these recording films is formed by a film forming method such as a resistance heating vacuum evaporation method, an electron beam vacuum evaporation method, and a sputtering method.
Since the recording film immediately after film formation is in a kind of amorphous state, in order to perform recording on this recording film and form an amorphous recording portion, initialization for converting the entire recording film to crystalline is performed. Processing is performed. Recording is achieved by forming amorphous portions in this crystallized state.

A general phase change type optical disk recording / reproducing method changes the power of a laser beam between two levels,
By performing crystallization or amorphization. That is,
At the time of recording, the recording film is irradiated with a laser beam having a power capable of raising the temperature of the recording film to the melting point or higher, and the irradiated portion is made amorphous when cooled. When erasing information, a laser beam having a power such that the temperature of the recording film reaches a temperature higher than the crystallization temperature and lower than the melting point is applied. Reproduction is performed by irradiating a low-power laser beam and reading the difference in reflected light intensity.

As described above, the recording film of the phase-change optical disk is heated to a temperature higher than the melting point or higher than the crystallization temperature and lower than the melting point by a laser beam for recording and erasing information. You. Therefore, it is common to provide a dielectric protective film having excellent heat resistance on both sides of the recording film, and the recording / reproducing characteristics are repeatedly affected by the thickness, film configuration, and film quality of the protective film. S as one of the protective films
iO ₂ films are known. Conventionally, this SiO ₂ film is made of SiO ₂
It is formed by a sputtering method using _two targets and using an argon gas as a sputtering gas.

[0008]

However, the conventional SiO
_{In the} method of forming the _two films, since the SiO ₂ target is a sintered body, applying a large power to the target may damage the target, and therefore cannot apply a large amount of power. Was. Therefore, the film formation speed is extremely low, about 1.5 nm / min to 3.0 nm / min, and there is a problem that productivity is lacking. Further, when a SiO ₂ film is formed using an SiO ₂ target only in an argon gas atmosphere as in the prior art, high energy argon ions collide with the SiO ₂ target surface and the formed film surface. A porous film in which bonds between atoms and O atoms (oxygen atoms) are broken is formed. In order to compensate for this, a method of forming a SiO ₂ film in a mixed gas atmosphere of argon gas and oxygen gas is also known, but in this case, formation of dangling bonds of Si due to collision of argon ions is avoided. No, the membrane becomes porous.
Since such a porous film has a low density, there is also a problem that the protective film is thermally damaged by thermal shock due to temperature rise and rapid cooling during repeated recording and reproduction many times, and an error occurs during recording and reproduction. Was. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a SiO ₂ film having characteristics suitable as a protective film for a phase change type optical disk medium, and a protection for a phase change type optical disk medium manufactured using this SiO ₂ film. Provided are a film, a phase change type optical disk medium manufactured using the protective film, and capable of obtaining a stable signal characteristic even when performing a recording and reproducing operation many times repeatedly, and a manufacturing method excellent in productivity thereof. It is in.

[0009]

According to the present invention, there is provided a method for forming a film by sputtering using a Si target and a mixed gas of oxygen gas and argon gas as a sputtering atmosphere gas. Characteristic SiO ₂
Method for producing film and S produced by this method
An iO ₂ membrane is provided. In the above, it is preferable that the partial pressure of oxygen gas in the mixed gas of oxygen gas and argon gas used when forming the SiO ₂ film be in the range of 0.024 Pa to 0.12 Pa.

The present invention also provides a method for producing a SiO ₂ film, wherein a film is formed by sputtering using a Si target and a mixed gas of oxygen gas, argon gas and hydrogen gas as a sputtering atmosphere gas. And a SiO ₂ film manufactured by the manufacturing method. In the above, the oxygen gas partial pressure in the mixed gas of oxygen gas, argon gas and hydrogen gas used for forming the SiO ₂ film is 0.0
The pressure is in the range of 18 Pa to 0.06 Pa, and the partial pressure of hydrogen gas is 0.1 Pa.
It is preferable to be in the range of 006 Pa to 0.02 Pa.
Wherein in any of the manufacturing method, the density of the SiO ₂ film is preferably in the range of ^{2.1g / cm 3 ~2.5g / cm 3} .

The present invention is also characterized in that the protective film in a phase-change optical disk medium having at least a protective film made of a SiO ₂ film and a phase-change recording layer is manufactured by any one of the above-mentioned manufacturing methods. Provided are a method for manufacturing a protective film for a phase change type optical disk medium, and a protective film for a phase change type optical disk medium manufactured by the manufacturing method.

[0012] The present invention further protective layer made of at least SiO ₂ film to the organic resin substrate, a first dielectric layer made of ZnS-SiO ₂ film, a phase-change recording layer, a second made of ZnS-SiO ₂ film When manufacturing a phase change optical disk medium formed of a dielectric layer and a metal reflective layer in this order,
A method for manufacturing a phase-change optical disk medium, wherein the protective film is manufactured by the method for manufacturing a protective film for a phase-change optical disk medium, and a phase-change optical disk manufactured by the method. Provide media.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a cross-sectional configuration diagram of a phase change type optical disk medium (hereinafter, simply referred to as “medium”) according to the present invention. This medium has a thickness of 0.6 mm and a diameter of 1
On a substrate 1 made of polycarbonate of 20 mm,
100 nm thick protective film 2 made of O ₂ film, ZnS-Si
O ₂ thickness 20nm consisting film first dielectric layer 3, a thickness of 18n
m phase change recording layer 4, thickness 2 composed of ZnS—SiO ₂ film
A second dielectric layer 5 having a thickness of 0 nm and a metal reflecting layer 6 having a thickness of 70 nm are formed, and after this series of film forming processes, an ultraviolet curable resin 7 is applied and cured. In this embodiment, a thin film of Ge ₂ Sb ₂ Te ₅ is used as the phase change recording layer 4, and a thin film of an AlTi alloy is used as the metal reflection layer 6. This medium may be used in the above-mentioned single-plate structure, or may be used in a disk-bonding adhesive (such as an ultraviolet-curing resin) or in a close-bonded structure.

(Embodiment 1) An embodiment in which a mixed gas of oxygen gas and argon gas is used as a sputtering atmosphere gas using a Si target will be described below. In this manufacturing method, each of the above layers is formed on the substrate 1 by the following procedure using an in-line type sputtering apparatus. First, SiO ₂
The protective film 2 having a thickness of 100 nm made of a film is formed by using a Si target, a distance of 15 cm between the Si target and the substrate 1 and a power density of 2 in a mixed gas of oxygen gas and argon gas as a sputtering atmosphere gas. The film is formed under the conditions of 0.74 W / cm ² , a total gas pressure of 0.2 Pa, and an oxygen gas partial pressure of 0.06 Pa.

Next, a ZnS-SiO ₂ film having a thickness of 2
The first dielectric layer 3 having a thickness of 0 nm was formed by using a ZnS-SiO ₂ target in an argon gas atmosphere with a target-substrate distance of 15 cm, a power density of 2.2 W / cm ² , and a gas pressure of 0.5 Pa. The film is formed under the conditions.

The phase change recording layer 4 made of a Ge ₂ Sb ₂ Te ₅ film and having a thickness of 18 nm is made of a Ge ₂ Sb ₂ Te ₅ target in an argon gas atmosphere with a target-substrate distance of 15 cm and a power density of Is formed under conditions of 0.27 W / cm ² and a gas pressure of 1.0 Pa.

Further, a thickness _{2 made of} a ZnS-SiO ₂ film
The second dielectric layer 5 of 0 nm is formed under the same conditions as the first dielectric layer 3. The metal reflective layer 6 made of an AlTi alloy film and having a thickness of 70 nm was formed using an AlTi alloy target containing 2% by weight of Ti, in an argon gas atmosphere, a distance between the target and the substrate of 15 cm, and a power density of 1.6 W /. The film is formed under the conditions of cm ² and a gas pressure of 0.08 Pa. The film formation time of each of the layers was appropriately adjusted so as to have a desired film thickness.

In the method for manufacturing a medium, the gas pressure of the sputtering atmosphere gas used for forming the protective film 2 made of a SiO ₂ film is changed within the range of 0.07 Pa to 0.60 Pa, The medium was manufactured by changing the partial pressure within the range of 0.021 Pa to 0.180 Pa, and the C / N ratio when the recording / reproducing operation (hereinafter referred to as “repetitive O / W”) was repeatedly performed.
Was measured for each medium. In Table 1,
The type of the medium for which the O / W was repeatedly measured, the gas pressure of the sputtering atmosphere gas and the partial pressure of the oxygen gas during the formation of the SiO ₂ film are shown. The gas pressure of the sputtering atmosphere gas was set to 0.06 Pa
The measurement was also performed when the oxygen gas partial pressure was 0.018 Pa. In this case, the oxygen gas partial pressure in the sputtering atmosphere was low, the degree of surface oxidation of the Si target was insufficient, and the R / W evaluation was low. Since it was not possible, it was not described in Table 1.

[0019]

[Table 1]

During the production of each of the above media, the thickness of each dielectric layer was adjusted so that the optimum overwrite power became substantially equal. As a result, the optimum overwrite power was set to 8.7 mW for the recording power and 4 mW for the erasing power. The R / W evaluation conditions were as follows: a linear velocity of 5.4 m / sec, a frequency of 29.18 MHz, a reproduction power of 0.8 mW, and an 8T single signal repetitive O / W by the above-mentioned optimal overwrite power. After the desired number of O / W cycles, C / N
Was measured.

FIG. 2 shows the amount of decrease in C / N with respect to the number of repeated O / Ws for each medium. From FIG.
In the oxygen gas partial pressure of SiO ₂ film media A~ medium was used which was formed within the 0.021Pa~0.06Pa C, 10 ⁵ times no deterioration even C / N after repeating O / W of It was not observed and showed the same value as the C / N initial value. In the medium D using an SiO ₂ film formed at an oxygen gas partial pressure of 0.12 Pa,
Although up to 10 ^four times was not seen deterioration in C / N,
After 10 ⁵ iterations O / W, C / N is compared with the initial value, were decreased as slightly 1 dB. In the medium E using a SiO ₂ film formed at an oxygen gas partial pressure of 0.18 Pa,
10 ³ repetitions O / W C / N is gradually deteriorated beginning from later, after 10 ⁵ iterations O / W, C / N is degraded even 5dB compared to the initial value. From the viewpoint of the amount of decrease in C / N, it can be seen that the preferable upper limit of the oxygen gas partial pressure is 0.18 Pa.

FIG. 3 shows the relationship between the partial pressure of oxygen gas and the deposition rate of the SiO ₂ film. As shown in FIG. 3, as the oxygen gas partial pressure increases, the deposition rate of the SiO ₂ film once increases and then decreases. It has been found that in a region where the film formation rate increases with an increase in the oxygen gas partial pressure, the degree of oxidation of the Si target surface is insufficient, and a metallic SiO ₂ film is formed. Therefore, R / W evaluation could not be performed in a region where the oxygen gas partial pressure was less than 0.024 Pa. From the viewpoint of the deposition rate of the SiO ₂ film, it is understood that the lower limit of the suitable oxygen gas partial pressure is 0.024 Pa.

In the conventional method of forming the protective film 2 using the SiO ₂ target, the film forming speed is 1.5 nm / min.
In contrast, the SiO ₂ film was formed by reactive sputtering using the above-mentioned Si target and a mixed gas of argon gas and oxygen gas as a sputtering atmosphere gas. The film speed is about 4 times to 1 times of the conventional method.
It became possible to make it about 0 times.

As described above, according to the present invention, a film is formed by sputtering using a Si target and a mixed gas of oxygen gas and argon gas as a sputtering atmosphere gas.
_{In the two-} film manufacturing method, it is preferable that the partial pressure of the oxygen gas in the mixed gas is in a range of 0.024 Pa to 0.12 Pa.

Next, the density of the SiO ₂ film will be described. FIG. 4 shows the relationship between the oxygen gas partial pressure and the SiO ₂ film (film thickness = 100 nm) when the oxygen gas partial pressure when forming the SiO ₂ film was changed within the range of 0.021 Pa to 0.18 Pa. The relationship with the film density is shown. FIG. 4 shows that the film density tends to decrease as the oxygen gas partial pressure increases. Referring to FIGS. 2 and 4, the film density of the SiO ₂ film without problems repeatedly O / W characteristics, it can be seen that in the range of ^{2.1g / cm 3 ~2.5g / cm 3} . From this viewpoint, using a Si target,
The S of the present invention, in which a film is formed by sputtering using a mixed gas of oxygen gas and argon gas as a sputtering atmosphere gas
In the manufacturing method of the iO ₂ film, the density of the SiO ₂ film is as follows.
It is preferably in the range of ^{1g / cm 3 ~2.5g / cm 3} .

(Embodiment 2) Next, an embodiment using a Si target and a mixed gas of oxygen gas, argon gas and hydrogen gas as a sputtering atmosphere gas will be described. In this manufacturing method, the configuration of the medium is the same as that of the first embodiment. Each layer of this medium is formed on the substrate 1 by the following procedure using an in-line type sputtering apparatus. First, Si
The protective film 2 having a thickness of 100 nm made of an O ₂ film is formed by using a Si target in a mixed gas of an oxygen gas and a hydrogen gas mixed with an argon gas as a sputtering atmosphere gas.
The distance between the target and the substrate 1 was 15 cm, the power density was 2.74 W / cm ² , the total gas pressure was 0.1 Pa, the oxygen gas partial pressure was 0.03 Pa, and the hydrogen gas partial pressure was 0.01 Pa. Filmed.

Next, a ZnS—SiO ₂ film having a thickness of 2
The first dielectric layer 3 having a thickness of 0 nm was formed by using a ZnS-SiO ₂ target in an argon gas atmosphere with a target-substrate distance of 15 cm, a power density of 2.2 W / cm ² , and a gas pressure of 0.5 Pa. The film is formed under the conditions.

The phase change recording layer 4 made of a Ge ₂ Sb ₂ Te ₅ film and having a thickness of 18 nm is formed by using a Ge ₂ Sb ₂ Te ₅ target in an argon gas atmosphere with a target-substrate distance of 15 cm and a power density of Is formed under conditions of 0.27 W / cm ² and a gas pressure of 1.0 Pa.

The thickness _{2 of} the ZnS-SiO ₂ film
The second dielectric layer 5 of 0 nm is formed under the same conditions as the first dielectric layer 3. The metal reflective layer 6 made of an AlTi alloy film and having a thickness of 70 nm was formed using an AlTi alloy target containing 2% by weight of Ti, in an argon gas atmosphere, a distance between the target and the substrate of 15 cm, and a power density of 1.6 W /. The film is formed under the conditions of cm ² and a gas pressure of 0.08 Pa. The film formation time of each of the layers was appropriately adjusted so as to have a desired film thickness.

In the method for manufacturing a medium, the medium is manufactured by changing the gas pressure of the sputtering atmosphere gas used in forming the protective film 2 made of a SiO ₂ film in the range of 0.04 Pa to 0.4 Pa. The amount of decrease in C / N upon repeated O / W was measured for each medium. Table 2 shows the type of the medium for which the O / W was repeatedly measured, the gas pressure of the sputtering atmosphere gas, the oxygen gas partial pressure, and the hydrogen gas partial pressure when forming the SiO ₂ film. The measurement was also performed when the gas pressure of the sputtering atmosphere gas was set to 0.04 Pa, the oxygen gas partial pressure was set to 0.012 Pa, and the hydrogen gas partial pressure was set to 0.004 Pa. Pressure is low, the degree of surface oxidation of the Si target becomes insufficient,
Not shown in Table 2 because a metallic film was formed and therefore could not be evaluated for R / W.

[0031]

[Table 2]

During the production of each of the above-mentioned media, the thickness of each dielectric layer was adjusted so that the optimum overwrite power became almost equal. As a result, the optimum overwrite power was set to 8.7 mW for the recording power and 4 mW for the erasing power. The R / W evaluation conditions were as follows: a linear velocity of 5.4 m / sec, a frequency of 29.18 MHz, a reproduction power of 0.8 mW, and an 8T single signal repetitive O / W by the above-mentioned optimal overwrite power. After the desired number of O / W cycles, C / N
Was measured.

FIG. 5 shows the amount of decrease in C / N with respect to the number of repeated O / Ws for each medium. From FIG.
SiO formed with a partial pressure of oxygen gas of 0.015 Pa to 0.03 Pa and a partial pressure of hydrogen gas of 0.005 Pa to 0.01 Pa
_In the mediums F to H using the _two films, O ⁵ repetitions were performed 105 times.
Even after / W, C / N did not show any deterioration and showed the same value as the C / N initial value. Oxygen partial pressure of 0.06 Pa, at medium partial pressure of hydrogen gas was used SiO ₂ film formed by 0.02 Pa I, although up to 10 ⁴ times the degradation was not observed in the C / N, 10 ⁵ After repeated O / W times, the C / N decreased slightly by 0.5 dB from the initial value. In a medium J using an SiO ₂ film formed at an oxygen gas partial pressure of 0.12 Pa and a hydrogen gas partial pressure of 0.04 Pa, O ³ times repeated O
C / N gradually began to deteriorate after / W, and after 10 ⁵ repetitions of O / W, C / N deteriorated by 4 dB compared to the initial value. From the viewpoint of the amount of decrease in C / N, it can be seen that the upper limit of the suitable oxygen gas partial pressure in this example is 0.06 Pa.

FIG. 6 shows the relationship between the oxygen gas partial pressure and the hydrogen gas partial pressure and the SiO ₂ film formation rate. FIG. 6 shows that as the oxygen gas partial pressure and the hydrogen gas partial pressure increase, the SiO ₂
The film formation rate once increased and then decreased. In the region where the film formation rate increases with the increase of the oxygen gas partial pressure and the hydrogen gas partial pressure, it was found that the degree of oxidation of the Si target surface was insufficient and a metallic SiO ₂ film was formed. . For this reason, in the region where the oxygen gas partial pressure is less than 0.012 Pa and the hydrogen gas partial pressure is less than 0.004 Pa, R / W
Could not be evaluated. From the viewpoint of the deposition rate of the SiO ₂ film, it can be seen that the lower limit of the preferable partial pressure of oxygen gas is 0.018 Pa and the lower limit of the partial pressure of hydrogen gas is 0.006 Pa.

In the conventional method of forming the protective film 2 using the SiO ₂ target, the film forming speed is 1.5 nm / min.
Whereas ～3.0Nm / were min, and using the above Si target, a mixed gas of argon gas and oxygen gas and hydrogen gas as a sputtering atmosphere gas, SiO ₂ at the time of forming by a reactive sputtering The film deposition rate can be about three to ten times that of the conventional method.

As described above, in the method for producing an SiO ₂ film according to the present invention, in which a film is formed by sputtering using a Si target and a mixed gas of oxygen gas, hydrogen gas and argon gas as a sputtering atmosphere gas, The partial pressure of oxygen gas in the range of 0.018Pa to 0.06Pa,
The partial pressure of the hydrogen gas is desirably in the range of 0.006 Pa to 0.02 Pa.

FIG. 7 shows that the oxygen gas partial pressure was changed within the range of 0.015 Pa to 0.12 Pa and the hydrogen gas partial pressure was changed within the range of 0.005 Pa to 0.04 Pa when forming the SiO ₂ film. The relationship between the gas partial pressure and the film density of the SiO ₂ film (film thickness = 100 nm) in the case of FIG. As shown in FIG. 7, the film density decreases as the oxygen gas partial pressure and the hydrogen gas partial pressure increase. Referring to FIG. 5 and FIG. 7, SiO _{2 having} no problem in the repeated O / W characteristics
Range of film density of the film is found to be in the range of ^{2.3g / cm 3 ~2.5g / cm 3} .

As described in detail in the first embodiment, when forming the SiO ₂ film which is the protective film of the phase change type optical disk medium, using a Si target, a mixed gas of oxygen gas and argon gas as a sputtering atmosphere gas. When a film is formed by sputtering using the method described above, by setting the oxygen gas partial pressure in the mixed gas to be in the range of 0.024 Pa to 0.12 Pa, the film forming speed can be significantly improved as compared with the conventional film forming method. It is possible to obtain a phase change type optical disk medium which is fast and has excellent durability without C / N deterioration after repeated O / W. Further, as described in detail in Example 2, when film formation is performed by sputtering using a Si target and a mixed gas of oxygen gas, argon gas, and hydrogen gas as the sputtering atmosphere gas, Reduce the oxygen gas partial pressure to 0.
Within the range of 018 Pa to 0.06 Pa, the hydrogen gas partial pressure is set to 0.0
By setting the pressure within the range of 0.6 Pa to 0.02 Pa, the film forming speed is remarkably higher than that of the conventional film forming method, and O
Thus, a phase change type optical disk medium having excellent durability without C / N deterioration after / W is obtained.

In the phase change type optical disk medium of the present invention, the composition of the phase change recording layer and the metal reflection layer, the single-plate structure or the bonding structure, and the respective film thickness and bonding method in the case of the bonding structure are as follows. It is not particularly limited,
It can be appropriately selected according to desired recording / reproducing characteristics and applications, and it goes without saying that the present invention has the same effect as described above for any of these selections.

[0040]

As described above, according to the present invention, when forming the SiO ₂ film as the protective film, the Si target is used.
Since film formation is performed by sputtering using a mixed gas of oxygen gas and argon gas or a mixed gas of oxygen gas, argon gas and hydrogen gas as a sputtering atmosphere gas, productivity and repetitive O / W characteristics are improved. An excellent phase-change optical disk medium can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a phase change type optical disk medium of the present invention.

[2] When a SiO ₂ film in a mixed gas atmosphere of argon gas and oxygen gas, in the case of using the SiO ₂ film formed on each different oxygen gas partial pressure, repeating O of each medium 6 is a graph showing the amount of decrease in C / N due to / W.

FIG. 3 is a graph showing a film formation rate with respect to each oxygen gas partial pressure when a SiO ₂ film is formed in a mixed gas atmosphere of an argon gas and an oxygen gas.

FIG. 4 is a graph showing the density of the SiO ₂ film with respect to each oxygen gas partial pressure when the SiO ₂ film is formed in a mixed gas atmosphere of an argon gas and an oxygen gas.

[5] in a mixed gas atmosphere of oxygen gas and argon gas and hydrogen gas in formation of the SiO ₂ film was used SiO ₂ film formed on each different oxygen gas partial pressure and hydrogen gas partial pressure C / N by repeated O / W of each medium in case
The graph which shows the fall amount of.

FIG. 6 is a graph showing a film forming rate with respect to each oxygen gas partial pressure and hydrogen gas partial pressure when a SiO ₂ film is formed in a mixed gas atmosphere of oxygen gas, argon gas, and hydrogen gas.

FIG. 7 is a gas mixture of oxygen gas, argon gas and hydrogen gas.
SiO in the atmosphere _TwoEach oxygen gas when a film is formed
SiO for partial pressure_Two5 is a graph showing the density of a film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Protective film 3 ... 1st dielectric layer 4 ... Phase change recording layer 5 ... 2nd dielectric layer 6 ... Metal reflection layer 7 ... Ultraviolet curing resin

Claims (10)

[Claims] An SiO ₂ film is formed by sputtering using a Si target and a mixed gas of an oxygen gas and an argon gas as a sputtering atmosphere gas.
Manufacturing method of membrane. 2. An oxygen gas partial pressure in a mixed gas of an oxygen gas and an argon gas used for forming an SiO ₂ film is set to 0.02.
SiO ₂ film manufacturing method according to claim 1, characterized in that in the range of 4Pa～0.12Pa. 3. A method for producing a SiO ₂ film, wherein a film is formed by sputtering using a Si target and a mixed gas of oxygen gas, argon gas and hydrogen gas as a sputtering atmosphere gas. 4. A partial pressure of oxygen gas in a mixed gas of oxygen gas, argon gas and hydrogen gas used for forming the SiO ₂ film is set to be in a range of 0.018 Pa to 0.06 Pa, and a partial pressure of hydrogen gas is set to zero. SiO ₂ film manufacturing method according to claim 3, characterized in that in the range of .006Pa～0.02Pa. 5. The density of the SiO ₂ film is from 2.1 g / cm ³ to
SiO ₂ film manufacturing method according to any one of the claims 1 to 4, characterized in that in the range of 2.5 g / cm ^3. Wherein the protective layer in a phase change type optical disc medium and at least made of SiO ₂ film protective film and the phase change recording layer, the SiO ₂ film according to any one of the claims 1 to 5 A method for producing a protective film for a phase-change optical disk medium, characterized by being produced by the method described in (1). 7. A protective film comprising at least SiO ₂ film to the organic resin substrate, a first dielectric layer made of ZnS-SiO ₂ film, a phase-change recording layer, a second dielectric made of ZnS-SiO ₂ film 7. When manufacturing a phase-change optical disk medium formed by depositing a layer and a metal reflective layer in this order, manufacturing the protective film by the method for manufacturing a protective film for a phase-change optical disk medium according to claim 6. A method for manufacturing a phase change type optical disk medium. 8. The SiO ₂ film, which is manufactured by the manufacturing method of the SiO ₂ film according to any one of the claims 1 to 5. 9. A protective film for a phase change type optical disk medium, which is manufactured by the method for manufacturing a protective film for a phase change type optical disk medium according to claim 6. 10. A phase change type optical disk medium manufactured by the method of manufacturing a phase change type optical disk medium according to claim 7.