JPH07138748A - Thin film and its production as well as glass forming mold utilizing this film - Google Patents

Abstract

PURPOSE:To easily form a thin film which is dense, has an excellent adhesion property and small film stress and is formable thinner on a substrate by simultaneously executing film formation by a sputtering method and film formation by a CVD method in a vacuum chamber. CONSTITUTION:For example, a glass forming mold base material 6 is placed on a holder 5 in the vacuum chamber 4 and a target 3 consisting of carbon or carbide is disposed in a position opposite thereto at the time of forming a carbon film as a protective film on the surface of the glass forming mold base material. An inert gas, such as Ar, is introduced from a sputtering gas introducing port 1 and a carbon-contg. CVD gas, such as CH4, is introduced from a CVD gaseous raw material introducing port 2 into the vacuum chamber 4 to sputter the carbon-contg. target 3. The gaseous CH4 is cracked by utilizing the plasma generated at the time of the sputtering, by which the carbon thin film of the excellent characteristics consisting of the C by the sputtering and the cracked C by the CVD method is stably formed on the surface of the base material 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film used for a protective film of a glass molding die, a method for producing the thin film, and a glass molding die using the thin film.

[0002]

2. Description of the Related Art Conventionally, for example, a carbon film (including diamond) has been generally used as a protective film of SiC used as a base material of a mold for glass molding. This carbon film is generally a diamond-like carbon film (DLC) formed by a CVD method or an ion plating method, or a hard carbon film formed by a sputtering method.

Japanese Patent Publication No. 4-61816 discloses at least a method of obtaining hard carbon by using a sputtering method using graphite as a target, a substrate temperature of 250 to 450 ° C., and an inert gas (Ar) as a sputtering gas. Plasma sputter deposition or plasma ion plating in an atmosphere containing hydrogen, ECR plasma CV
A method for obtaining a hydrogenated amorphous carbon film by using either the D method or the ion beam vapor deposition method is disclosed in JP-A-2-149435.
Japanese Patent Laid-Open Publication No. 2003-242242 discloses a method of obtaining a hydrogenated amorphous carbon film by using any one of RF plasma CVD method, ion beam method, ion plating method, sputtering method, or a combination thereof. Films formed into one glass mold) are disclosed in JP-A-2-283627.

[0004]

The film obtained by the conventional sputtering method has good adhesion and is hard and dense.
On the other hand, it is known that in the case of a thick film having a large film stress of 1 μm or more, film cracking and partial peeling occur, and the uneven shape of the substrate and the material are easily affected.

It is known that a film obtained by the CVD method has a small film stress and can be made relatively thick, but is softer and rougher than the sputtering method.

Therefore, an object of the present invention is to combine the advantages of both of the above-mentioned methods, and the obtained film has good adhesion and is hard, but the film stress is relatively small and the substrate An object of the present invention is to provide a method suitable for forming a protective film or the like of a glass mold, which is less likely to be affected by the uneven shape and the material.

Another object of the present invention is to provide a thin film formed by using the above method and a glass molding die using the thin film.

[0008]

In order to achieve the above object, a method of manufacturing a thin film according to the present invention is an apparatus in which a sputtering chamber introducing a sputtering gas and a CVD source gas introducing port are provided in a vacuum chamber containing a target and a substrate. It is characterized in that the target and the CVD source gas contain at least one common element in a film forming method in which the film formation by the sputtering method and the film formation by the CVD method are performed at the same time.

The thin film obtained by the above method uses an inert gas as a sputtering gas. 1. Carbon or carbide as the target, hydrocarbon or oxygen as the CVD source gas, 2. 2. Boride as a target, hydrogen boride as a CVD source gas, and 3. It is characterized in that a silicon compound is used as a target and silane is used as a CVD source gas.

Further, the present invention is characterized in that a glass molding die is obtained by utilizing the thin film obtained by the film forming method.

[0011]

With the above structure, the present invention utilizes the plasma generated during sputtering by introducing a gas as a CVD raw material in a relatively high concentration mixed with an inert gas at the same time as the film formation by the sputtering method. The CVD source gas is decomposed and a thin film is chemically formed by the CVD method.

[0012]

[Example] Considering film formation by a sputtering method,
There are drawbacks as described above. Therefore, in order to eliminate this defect, a CVD source gas is introduced into a vacuum chamber in which the sputtering method is performed, and film formation by the CVD method is also performed in the same vacuum chamber at the same time as the sputtering method. The present invention is a method of compensating for the drawbacks of the sputtering method, which enables a relatively thick film.

However, in the general sputtering method, the degree of vacuum is about 1 × 10 to ¹ to 1 × 10 to ³ Torr, which is different from the degree of vacuum of the CVD method of about 10 to ¹ × 10 to ¹ Torr. Therefore, it is not possible to form films simultaneously.

Therefore, using a magnetron sputtering method having a magnetron cathode capable of concentrating the plasma density in the vicinity of the target to increase the density,
The degree of vacuum is set to about 1 × 10 to ¹ to 1 × 10 to ² Torr, and CVD is performed.
A raw material gas is mixed with an inert gas at a relatively high concentration and introduced, and is simultaneously decomposed by utilizing high-density plasma in the vicinity of the target generated during sputtering to chemically form a thin film.

A method for forming a thin film using the apparatus shown in FIG. 1 will be described below as an embodiment of the present invention.

This apparatus is an improved apparatus for carrying out the sputtering method, and includes a vacuum chamber 4, a sputtering gas inlet port 1 for introducing a sputtering gas into the vacuum chamber 4, and a CVD source gas for introducing a CVD source gas. Introduction port 2,
It comprises a conductance valve 7 for controlling the degree of vacuum in the vacuum chamber 4, a target 3 arranged in the vacuum chamber 4, and a substrate holder 5. The substrate 6 to be coated with the thin film is placed on the substrate holder 5 in the vacuum chamber 4.

First, the vacuum chamber 4 is evacuated to a high vacuum, and the sputter gas is introduced through the sputter gas introduction port 1 and the CVD raw material gas is introduced through the CVD raw material gas introduction port 2. The target 3 and the CVD source gas should contain at least one common element.

Next, discharge is performed in this state. D for discharge
The C power source is used, but the DC power source can be used only when the target 3 is a conductor. Therefore, when the target 3 is an insulator such as BN or SiC, or when the discharge is unstable, R is used.
It suffices to discharge using an F power supply. That is, the type of power source may be determined according to the target material and shape, the type and pressure of the introduced gas.

Plasma is generated between the target 3 and the substrate 6 by the discharge, and positive ions are generated from the sputter gas.
Atoms on the surface are knocked out, and a film formed by a sputtering method is formed on the substrate 6 by the hammered out atoms. At the same time, the CVD source gas reacts, and CVD is performed on the substrate 6.
A film is formed by the method.

Since the target 3 and the CVD source gas contain at least one or more common elements, the formed film is a film containing this common element.

Next, an experimental example of actually manufacturing a thin film (carbon film) using this apparatus will be described. When forming a carbon film, a carbon plate (sintered carbon, graphite, etc.) was used as the target 3. As the gas to be used, Ar gas is introduced as the sputter gas from the sputter gas introduction port 1, and the CVD raw material gas introduction port 2 is used as the CVD raw material gas.
CH ₄ gas was introduced.

The inside of the vacuum chamber 4 is evacuated to a high vacuum of 1 × 10 to ⁶ Torr or less, and then a total of 5 × 10 5 of each gas is supplied from the sputter gas introduction port 1 and the CVD source gas introduction port 2.
Introduced to be ~ ⁴ Torr. After that, the conductance valve 7 is gradually closed so that the entire vacuum degree is 6 × 10 to ³ Torr.
I chose Next, discharge is performed in this state to generate plasma. In this experimental example, the target 3 (-) and the substrate holder 5 (+) were set to 600 V DC and the substrate holder 5
Plasma was generated in the form of being grounded. It should be noted that the substrate holder 5 may be bias sputter with a slight bias applied without being grounded.

Under these conditions, the results of forming a film by changing the pressures of Ar gas and CH ₄ gas are shown in FIG. 2 (where CH ₄ concentration = CH ₄ gas pressure / (Ar gas + CH ₄ gas) pressure × 10).
0 (%)).

In the general sputtering method, when another gas is mixed in addition to the sputtering gas, the film thickness of the film formed decreases as the concentration of the mixed gas increases. This is because the concentration of the sputter gas (Ar gas) is lowered by the mixed gas, the probability that the sputter gas sputters the target is lowered, and the film formation rate is lowered. This is clearly shown by the reactive sputtering method in which oxygen and hydrogen are mixed.

Further, in the CVD method, the film thickness of the film formed increases as the concentration of the CVD source gas increases. This is because as the CVD source gas increases, the rate at which the CVD source gas is chemically decomposed to form a thin film increases.

Applying the above reasons to this experimental example, first, assuming that the sputtering method is used, the film formed as the CH ₄ gas concentration increases even in the region where the CH ₄ gas concentration is 0 to 40%. The film thickness should decrease, as shown in FIG.
Contradicts the result of.

Assuming the CVD method, the film thickness of the film to be formed should increase as the CH ₄ gas concentration increases even in the region where the CH ₄ gas concentration is 40 to 100%. It contradicts the result of 2.

Considering these things, in this experimental example,
It can be seen that the sputtering method and the CVD method are performed simultaneously.

[0029] Looking in more detail, it can be seen that the film thickness as the concentration of CH ₄ gas increases in CH ₄ region concentration of 0-40% of the gas in FIG. 2 is increased. this is,
This is because the increase in the film thickness by the CVD method is larger than the decrease in the film thickness by the sputtering method.

The concentration of CH ₄ gas is 40 to 100%.
It can be seen that the film thickness decreases in the region (2) as the CH ₄ gas concentration increases. This is because the decrease in the film thickness by the sputtering method is larger than the increase in the film thickness by the CVD method.

From this, it is in the region where the CH ₄ gas concentration is at least 20 to 70%, preferably 30 to 50% that both sputtering and CVD are sufficiently performed.

Next, FIG. 3 shows the relationship between the CH ₄ gas concentration and the discharge voltage when plasma discharge is performed with direct current. With the discharge current maintained at 0.5 A, the discharge voltage can be increased by gradually increasing the CH ₄ gas concentration from the state where only the sputtering method is performed (CH ₄ gas concentration is 0%). You can see that it is decreasing. This is because the CH ₄ gas is decomposed and the reaction of the following formula occurs in the reaction in which the gas is ionized and emits electrons during plasma generation.

[0033]

[Chemical 1]

That is, since hydrogen produced by decomposition of CH ₄ gas is further ionized to release electrons, the higher the concentration of CH ₄ gas, the lower the discharge voltage. From this fact, CH ₄ gas is decomposed to generate carbon (CVD
The law is in place).

From the above, it can be seen that in the film formation according to the present experimental example, the film formation by the sputtering method and the film formation by the CVD method are simultaneously performed in the same vacuum chamber.

Further, using the method of this experimental example, a convex R10
When a film was formed on a metal mold of mm, peeling occurred due to film stress in the conventional sputtering method (Ar 100%), but in the method of this experimental example, peeling was good.
In addition, when the film is formed by the CVD method (CH ₄ 100%),
Although the film was scratched at the time of glass molding, the scratch was not generated in this experimental example, which was good. From this, it is understood that the film formation according to the present experimental example provided a hard film in which the film stress was relaxed.

Next, an example of forming a glass molding die by using the thin film formed by the method of the present invention will be described. Using SiC as a substrate material, the substrate was processed into a shape corresponding to the shape of the glass molded body to be manufactured, and then a hard film was formed by the combination shown in Table 1.

[0038]

[Table 1]

The ratio of the sputter gas to the CVD source gas and other film forming conditions are the same as in the case of forming the carbon film described above. Examples of actual glass molding using the glass molds having the respective hard films will be described below in Molding Examples 1 to 3.

Molding Example 1 SiO ₂ —B ₂ O ₃ —La ₂ O ₃ type glass (crown type glass, glass transition point (hereinafter referred to as Tg): 631 ° C., yield point (hereinafter referred to as At): A method of performing molding at 657 ° C.) will be described.

FIG. 4 is a schematic view of the apparatus according to this embodiment. Reference numeral 11 denotes an upper mold, which has a mirror surface 12 (convex R10 mm) to be transferred to the lens at the time of molding. The upper mold 11 has a carbon film (2000 A) formed on a base material SiC. 21 is a lower mold, which is also a mirror surface 22 (concave R50m
m), and the material composition is the same as the upper mold. The upper mold 11 and the lower mold 21 are held by mold holders 13 and 23, respectively.

Next, molding is performed. First, as shown in FIG. 4A, the glass 31 is set on the lower mold 21. In this state, heating is performed up to 680 ° C. using a heating means (not shown). It is held until the temperature of the glass and the mold become uniform, and pressed by a pressing means (not shown) (FIG. 4 (b)). In this embodiment, the pressing pressure is 100 kg / cm ² and the pressing time is 10 seconds. By this pressing, the glass 31 is molded into the meniscus lens 32. When the pressing is completed, cooling is performed as it is, and the meniscus lens 32 is taken out when the temperature becomes equal to or lower than the glass Tg. In this way, the meniscus lens 32 is obtained (FIG. 4).
(C)).

As a result of repeating the molding according to the present example 100 times, the surface condition of the mold did not change and the meniscus lens 32 obtained was good.

Molding Example 2 Next, Nb ₂ O ₅ —P ₂ O ₅ —TiO ₂ based glass (Tg: 59)
A method of molding using 8 ° C and At: 656 ° C) will be described.

FIG. 5 is a schematic view of the apparatus according to this embodiment. An upper die 41 has a mirror surface 42 (convex R20 mm) to be transferred to the lens at the time of molding. The upper mold 41 has a boron nitride film (3000 A) formed on a base material SiC. 51 is a lower mold, and is also a mirror surface 52 (concave R40
mm) and the material composition is the same as the upper mold. The upper mold 41 and the lower mold 51 are held by mold holders 43 and 53, respectively.

Next, molding is performed. First, as shown in FIG. 5A, the glass 61 is set on the lower mold 51. In this state, heating is performed up to 650 ° C. using a heating means (not shown). It is held until the temperature of the glass and the mold become uniform, and pressed by a pressing means (not shown) (FIG. 5 (b)). In this embodiment, the pressing pressure is 80 kg / cm ² and the pressing time is 15 seconds. By this press, the glass 61 is molded into the meniscus lens 62. When the pressing is completed, cooling is performed as it is, and the meniscus lens 62 is taken out when the temperature becomes lower than the glass Tg. In this way, the meniscus lens 62 is obtained (FIG. 5).
(C)).

As a result of repeating the molding according to the present embodiment 200 times, the surface condition of the mold did not change, and the obtained meniscus lens 62 was also good.

It is also possible to mold the glass type molded in this embodiment with a mold coated with a carbon film as in the molding example 1. However, in this combination of glass type and mold, fusion tends to occur and the molding conditions tend to be narrow. Therefore, with respect to this glass material, the configuration of the present molding example 2 is most desirable.

Molding Example 3 Actually, SiO ₂ -PbO type glass (flint type glass,
A method of performing molding using Tg: 428 ° C., At: 466 ° C. will be described.

FIG. 6 is a schematic view of the apparatus according to this embodiment. Reference numeral 71 denotes an upper die, which has a mirror surface 72 (convex R30 mm) to be transferred to the lens at the time of molding. The upper die 71 has a SiC film (2000 A) formed on a base material SiC. 81 is a lower mold, and is also a mirror surface 82 (concave R40m
m), and the material composition is the same as the upper mold. The upper mold 71 and the lower mold 81 are held by mold holders 73 and 83, respectively.

Next, molding is performed. First, as shown in FIG. 6A, the glass 91 is set on the lower mold 81. In this state, heating is performed to 500 ° C. using a heating means (not shown). It is held until the temperature of the glass and the mold become uniform and pressed by a pressing means (not shown) (FIG. 6 (b)). In this embodiment, the pressing pressure is 100 kg / cm ² and the pressing time is 10 seconds. By this press, the glass 91 is molded into the biconvex lens 92. When the pressing is completed, cooling is performed as it is, and the biconvex lens 92 is taken out when the temperature becomes equal to or lower than the glass Tg. In this way, the biconvex lens 92 is obtained (FIG. 6C).

As a result of repeating the molding according to this example 150 times, the surface condition of the mold did not change, and the obtained biconvex lens 92 was also good.

In these molding examples, the biconvex spherical lens and the meniscus spherical lens are molded, but it goes without saying that the invention can also be applied to molding lenses of other shapes and further aspherical lenses. Further, it is desirable to fill the space around the mold with an inert gas atmosphere during molding.

[0054]

EFFECTS OF THE INVENTION According to the present invention, both the advantages of the sputtering method, that is, the dense and well-adhered film, and the advantages of the CVD method, that is, the film having a small film stress and capable of being thickened, have both advantages. A film can be obtained, and when used in a glass molding die, a hard and good adhesion film is obtained regardless of the shape of the mold (degree of unevenness).

[Brief description of drawings]

FIG. 1 is an explanatory view of a thin film manufacturing method according to an embodiment of the present invention.

FIG. 2 shows C in the thin film manufacturing method according to the experimental example of the present invention.
H ₄ is an explanatory diagram showing the relationship between the gas concentration and the film thickness.

FIG. 3 shows C in a thin film manufacturing method according to an experimental example of the present invention.
H ₄ is an explanatory diagram showing a relationship between gas concentration and the discharge voltage.

FIG. 4 is an explanatory view showing a molding process using the glass molding die of Molding Example 1 of the present invention.

FIG. 5 is an explanatory view showing a molding process using the glass molding die of Molding Example 2 of the present invention.

FIG. 6 is an explanatory view showing a molding process using the glass molding die of Molding Example 3 of the present invention.

[Explanation of symbols]

 1: Sputter gas introduction port 2: CVD gas introduction port 3: Target 4: Vacuum chamber 6: Substrate

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C23C 16/32 16/38 16/42

Claims (5)

[Claims] 1. A vacuum chamber including at least a target and a substrate; a means for introducing a sputtering gas into the vacuum chamber; and a means for introducing a CVD gas into the vacuum chamber, wherein the vacuum chamber is used. 2. A method for producing a thin film, characterized in that the target and the CVD source gas have at least one or more common elements in a film forming method in which sputtering and CVD are simultaneously performed. 2. A carbon film or a carbide film obtained by the method for producing a thin film according to claim 1, wherein carbon or carbide is used as the target, inert gas is used as the sputtering gas, and hydrocarbon or oxygen is used as the CVD source gas. 3. The boride film obtained by the method for producing a thin film according to claim 1, wherein a boride is used as a target, an inert gas is used as a sputtering gas, and borohydride (B ₂ H ₆ ) is used as a CVD source gas. 4. A silicon compound as a target, an inert gas as a sputtering gas, and silane (SiH ₄ ) as a CVD source gas.
A silicon compound film obtained by the method for producing a thin film according to claim 1, which comprises: 5. A glass molding die having a thin film obtained by using the method for producing a thin film according to claim 1.