JP3782206B2 - Film thickness correction mechanism for plasma CVD film formation - Google Patents

Description

【００３０】
【実施例３】
上記実施例１と同様にして、レンズの凸面を下向きにして成膜室にセットし、膜厚補正板を上面側と下面側の両方に取り付けた後、上面側成膜空間と下面側成膜空間の両方に、同時に、モノマーガスとしてジメチルジエトキシシランを１５０sccm、酸素を４５０sccm導入し、ＲＦ電力を６ｋＷ、レンズトレイの回転数を毎分２０回転としてレンズの両面すなわち凹面と凸面に同時に１０分間プラズマＣＶＤ成膜を行った。
【００３１】
【実施例４】
上記の実施例３における成膜条件と同じ条件で、上下の膜厚補正板のみを取り外してプラズマＣＶＤ成膜を行った。
【００３２】
その結果、次の表２と表３に示される比較データが得られた。表２は凸面の膜厚比較データであり、表３は凹面の膜厚比較データである。表２と表３で明らかなように、補正板有りの実施例３と補正板無しの実施例４では、１段目、２段目、３段目の各レンズに成膜された薄膜の膜厚に関して顕著な差異が生じている。膜厚補正板を用いた実施例３の方が１段目〜３段目の間での膜厚の差が小さくなっている。さらに成膜レートの観点でも膜厚補正板を用いた実施例３の方が１段目〜３段目の間での成膜レートの差が小さくなっている。
【００３３】
【表２】

【００３４】
【表３】

【００３５】
【発明の効果】
以上の説明で明らかなように本発明によれば、プラズマＣＶＤ成膜装置にてプラズマＣＶＤ法を利用して光学レンズ基材の両面または一方の面に薄膜を成膜する場合に、基板ホルダ上に配置された光学レンズ基材に対して所定の位置関係で膜厚補正板を配置することによって膜厚補正機構を付設したため、光学レンズ基材の表面におけるＣＶＤ膜の膜厚を均一にでき、良好な膜厚分布を実現することができる。特に、基板ホルダにおいて多数の光学レンズ基材を同心円の位置関係で配置する場合において、内側と外側に位置する光学レンズ基材の表面に成膜されるＣＶＤ膜の膜厚の差異を小さくし、基板ホルダ（レンズトレイ）を単位とするロット内の複数の光学レンズ基材における膜厚分布を均一にできる。
【図面の簡単な説明】
【図１】本発明に係る膜厚補正機構が付設されるプラズマＣＶＤ成膜装置の要部の内部構成図である。
【図２】図１におけるＡ−Ａ線断面図である。
【図３】基板ホルダにおけるプラスチック基材の配置状態と、膜厚補正板との位置関係を示す縦断面図である。
【符号の説明】
１１ プラスチック基材
１２ 基板ホルダ
１３ 真空処理室
１６ シールド板
１７，２７ 排気口
１８，２８ 反応ガス供給源
１９，２９ 反応ガス供給パイプ
２０，３０ プラズマ源
４１，４２ 膜厚補正板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film thickness correction mechanism for plasma CVD film formation, and in particular, when a film is formed on the surface of an optical lens substrate such as a spectacle plastic lens by a plasma CVD method, the plasma CVD process for making the film thickness uniform on the surface. The present invention relates to a film thickness correction mechanism for a film.
[0002]
[Prior art]
In recent years, for optical lenses such as eyeglass plastic lenses, a technique has been proposed in which a thin film is formed on the lens surface for the purpose of surface hardening using a plasma CVD method. The plasma CVD method, which is one of the film formation methods of semiconductor technology, can be expected to improve productivity and lens performance in forming a thin film on the surface of an optical lens. In film formation of an optical lens by plasma CVD, a plurality of optical lens substrates (lot units) are usually set in a circular flat plate holder, and film formation is performed for each lot while rotating the holder.
[0003]
[Problems to be solved by the invention]
Conventionally, film formation by plasma CVD (CVD film) was considered to have a good film thickness distribution. However, when plasma CVD is used to form a thin film for an optical lens, a more accurate and uniform film thickness is obtained. Distribution is required.
[0004]
In addition, when a CVD film is formed on the surface of the optical lens for the purpose of surface hardening or the like, ripples are generated in the spectral reflectance curve due to the difference between the refractive index of the optical lens and the refractive index of the CVD film. Since this ripple remains in the spectral reflectance curve even after an antireflection film is formed on the CVD film by, for example, vacuum deposition, it affects the reflection color of the appearance. Since the ripple interval depends on the thickness of the CVD film, if there is a difference in the thickness of the CVD film in each of the plurality of optical lenses in the lot, the reflection color (interference color) varies, and the wearing feeling of the optical lens Product value will be reduced.
[0005]
Furthermore, when there is a variation in the film thickness of the CVD film, the surface hardness varies between products, and it becomes difficult to maintain the quality of the optical lens at a certain level.
[0006]
An object of the present invention is to solve the above-described problem. When a thin film is formed on the surface of a plurality of optical lens substrates set on a holder using a plasma CVD method, the thin film formed on the surface is formed. It is an object of the present invention to provide a film thickness correction mechanism for plasma CVD film formation that can reduce the film thickness difference and make the film thickness distribution uniform.
[0007]
[Means and Actions for Solving the Problems]
The film thickness correction mechanism for plasma CVD film formation according to the present invention is configured as follows to achieve the above object.
[0008]
The first film thickness correction mechanism for plasma CVD film formation (corresponding to claim 1) is used in a film formation apparatus for forming a thin film on the surface of an optical lens substrate by plasma CVD, It is configured by providing a film thickness correction plate that corrects the film thickness difference of the thin film formed on the material surface, the surface of the optical lens substrate has a curvature, and a plurality of optical lens substrates are placed horizontally. In a circular plate holder (substrate holder) that is rotated and concentrically positioned in a horizontal position, the film thickness correction plate is located at a position remote from the substrate holder, the plasma source and the reactive gas supply pipe outlet, and the optical lens. It is a mask member for film thickness difference adjustment arrange | positioned in the direction which connects the peripheral part and center part of a substrate holder between base materials.
[0009]
According to the above configuration, the film thickness correction plate is disposed between the plasma source and the reaction gas supply pipe used for the CVD film formation and the optical lens base material, so that the reactive gas activated by the plasma can be obtained. By shielding and dispersing the contact with the optical lens substrate, the direct influence is reduced, thereby reducing the difference in film thickness of the thin film formed on multiple optical lens substrates in the lot, and the film thickness distribution. Increase the uniformity of the.
Further, the film thickness correction plate acts as a mask member to adjust the film thickness, and for example, for a large number of optical lens substrates arranged at three concentric positions on the substrate holder, the film thickness difference between the optical lens substrates between the concentric circles. Can be made small, and the film thickness distribution can be made uniform. In addition, the attachment position of the film thickness correction plate functioning as a mask member is one or both of the upper side and the lower side with respect to the optical lens substrate.
[0011]
In the first plasma CVD film thickness correction mechanism (corresponding to claim 2 ), in the first configuration, a thin film is formed on the upper and lower surfaces of the optical lens substrate, and the mask member is an upper mask member. It consists of a lower mask member. According to this configuration, when performing the plasma CVD film formation on the upper surface and the lower surface of the optical lens substrate at the same time, the film thickness difference can be corrected for each surface.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
[0013]
1 and 2 show an example of a plasma CVD apparatus to which a film thickness correcting mechanism according to the present invention is applied. With reference to FIG. 1, the configuration and film forming process of an apparatus (hereinafter referred to as a plasma CVD film forming apparatus) for forming a protective film for surface hardening on both surfaces of a plastic substrate using a plasma CVD method will be described. . FIG. 1 is a plan view showing the main part of the internal structure of the plasma CVD film forming apparatus. 2 is a cross-sectional view taken along line AA in FIG. According to this plasma CVD film forming apparatus, for example, the protective film is simultaneously formed on both surfaces of the plastic substrate 11. The substrate 11 is not limited to plastic, and may be a glass material.
[0014]
The plastic base material 11 is a base material for eyeglass plastic lenses, and is an example of a plastic optical component. A protective film is applied to both surfaces of the plastic substrate 11 in order to cure the surface as a spectacle plastic lens.
[0015]
Moreover, since the said plastic base material 11 is a spectacles plastic lens, both surfaces have a curvature. Specifically, one surface of both surfaces of the plastic substrate 11 is a concave surface, and the other surface is a convex surface. Such a plastic substrate 11 is a circular flat plate rotating around its center and a horizontally placed substrate holder (a lens tray for placing a plurality of plastic substrates. 12) is set horizontally. In this state, the plastic substrate 11 is usually concave on the upper surface side and convex on the lower surface side.
[0016]
The configuration of the plasma CVD film forming apparatus will be described with reference to FIGS. A substrate holder 12 in which a plurality of plastic base materials 11 are arranged is arranged in the vacuum processing chamber (film formation chamber) 13. The substrate holder 12 has a circular flat plate shape and is arranged in a horizontal state (horizontal state). The central portion of the substrate holder 12 is rotatably supported by the upper support member 14 and the lower support member 15. A motor (not shown) is built in the lower support member 15, and the substrate holder 12 is rotated around the center portion by this motor. A shield plate 16 is provided near the lower side of the substrate holder 12 so as not to obstruct the rotation operation of the substrate holder 12 and to obstruct the thin film formation of the plastic substrate 11. The interior of the vacuum processing chamber 13 is partitioned into upper and lower spaces by the substrate holder 12 and the shield plate 16. The upper space and the lower space of the vacuum processing chamber 13 become plasma CVD film formation spaces, respectively, and a thin film can be formed on the upper surface and the lower surface of the plastic substrate 11. In the plasma CVD film formation in each of the upper space and the lower space, the film formation conditions can be individually controlled.
[0017]
An upper exhaust port 17 is provided in the upper space of the substrate holder 12, and the pressure atmosphere in the upper space is adjusted by a vacuum pump through the upper exhaust port 17. Monomer gas is supplied to the upper space. The monomer gas is supplied from the upper reaction gas supply source 18 to the front surface of the upper plasma source (plasma gun) 20 via the upper reaction gas supply pipe 19. The supplied monomer gas is exposed to the plasma-like reaction gas supplied from the upper plasma source 20. The resulting reaction product is deposited on the upper surfaces of the plurality of plastic base materials 11 arranged on the substrate holder 12, and a thin film functioning as a protective film is formed on the upper surface of the plastic base material 11. For example, when tetraethoxysilane is used as the monomer gas and oxygen is used as the plasma-like reaction gas, silicon oxide can be deposited on the upper surface of the plastic substrate 11. Various other gases can be used as the monomer gas, and hydrogen, nitrogen, or the like can be used as the reaction gas.
[0018]
With the above configuration, in the film formation in the upper space, the film is formed on the upper surface of the plastic substrate 11 by appropriately selecting the reaction gas and the monomer gas and adjusting the flow rate and supply amount of each gas. Thin film property values such as film thickness, refractive index, and hardness of the thin film can be controlled. In addition, a high frequency (RF) inductive coupling type electrode is preferably used as the plasma source 20, and variations in the distribution of film thickness and thin film property values can be reduced. A high frequency (RF) inductively coupled plasma source includes a high frequency discharge chamber, a high frequency coil, a matching box, a high frequency power source, a reactive gas cylinder, and a mass flow. Reference numeral 21 denotes a neutralizer for neutralizing plasma ions.
[0019]
The lower space of the substrate holder 12 is also provided with a configuration that produces the same effect as that of the upper space described above. That is, the lower exhaust port 27, the lower reaction gas supply source 28, the lower reaction gas supply pipe 29, the lower plasma source 30, and the lower neutralizer 31 are installed. With this configuration, a protective film can be formed on the lower surface of the plastic substrate 11 disposed on the substrate holder 12.
[0020]
The film thickness correcting mechanism according to the present embodiment is attached to the plasma CVD film forming apparatus. The film thickness correction mechanism includes film thickness correction plates 41 and 42 disposed on the upper side and the lower side of the substrate holder 12. The film thickness correction plates 41 and 42 are installed in the vicinity of the reaction gas supply pipes 19 and 29. The film thickness correction plates 41 and 42 are functionally mask members for covering the plastic base material 11 that comes close to the reaction gas supply pipe by the rotation operation of the substrate holder 12. By covering several plastic substrates 11 with a film thickness correction plate that functions as a mask member having a desired coating pattern shape, the monomer gas (reactive gas) is partially blocked and deposited on the surface of each plastic substrate 11. It is possible to correct the film thickness of the thin film to make the film thickness uniform on the surface. The film thickness correction plates 41 and 42 are arranged with the longitudinal direction thereof in the direction of a straight line connecting the center portion and the peripheral portion of the substrate holder 12, that is, in the radial direction.
[0021]
FIG. 3 shows the upper film thickness correction plate 41 in an enlarged manner. In FIG. 3, the direction of the arrow 43 is the direction of the rotation center of the substrate holder 12, and the arrow 44 indicates the direction of the plasma source. The plurality of plastic base materials 11 are arranged in the substrate holding hole in which the substrate holder 12 is formed. As apparent from FIG. 3, the plastic substrate 11 is arranged in a state (horizontal state) where the upper surface is a concave surface and the lower surface is a convex surface. In the substrate holder 12, the plurality of plastic base materials 11 are arranged at substantially three concentric positions as shown in FIG. 2, for example.
[0022]
Since the correction accuracy increases as the film thickness correction plate 41 is closer to the plastic substrate 11, it is preferable that the film thickness correction plate 41 be closer to the plastic substrate. However, considering the workability and the danger due to contact, the optimum distance between the plastic substrate 11 and the film thickness correction plate 41 is about 1 to 3 cm. Further, the film thickness correcting plate 41 is arranged so as to be in the direction of a straight line connecting the central portion and the peripheral portion of the substrate holder 12 as described above and substantially parallel to the surface of the plastic substrate 11. Is preferred. The arrangement state of the film thickness correction plate 41 is not limited to this. Also, the attachment position of the lower film thickness correction plate 42 is substantially the same as the film thickness correction plate 41.
[0023]
Further, as shown in the figure, the planar shape of the film thickness correction plates 41 and 42 is usually sufficient if it is a rectangular shape having a predetermined length in the radial direction, and is not particularly limited in shape.
[0024]
Next, an example of a film forming procedure in the plasma CVD film forming apparatus will be described. Plasma CVD film-forming of the plastic base material 11 is performed based on the following procedures 1-9.
[0025]
Step 1: The CR39 lens (corresponding to the plastic substrate 11) is ultrasonically cleaned to make the surface clean.
Step 2: A plurality of the above lenses are set in a lens tray (corresponding to the substrate holder 12), and then a gate valve of the film forming chamber (corresponding to the vacuum processing chamber 13) is opened, and a tray rotating shaft (upper support) in the film forming chamber is opened. The lens tray is set on the member 14 and the lower support member 15).
Step 3: After closing the gate valve, evacuation of the film forming chamber is started.
Step 4: The lens tray is rotated at a predetermined rotational speed.
Step 5: After evacuating to a predetermined film formation degree of vacuum, monomer gas and oxygen are introduced into the film formation chamber from each introduction port at a predetermined flow rate.
Step 6: A predetermined RF power is applied to an RF plasma gun (corresponding to the plasma sources 20 and 30) to form a plasma CVD film on the surface of the lens.
Step 7: After film formation for a predetermined time, the supply of RF power, monomer gas, and oxygen is stopped, and film formation ends.
Step 8: Stop the exhaust and leak the film forming chamber to atmospheric pressure, then open the gate valve and take out the lens tray from the film forming chamber.
Step 9: Take out the lens having the CVD film formed on both sides thereof from the lens tray.
[0026]
[Example 1]
A CVD film was formed on the lower surface of the CR39 lens according to the above procedure. In this example, the lens was placed on the lens tray with the convex surface facing downward, and this lens tray was set in the film forming chamber. A film thickness correction plate (corresponding to the film thickness correction plate 42) having a width of about 5 cm is disposed about 3 cm below the lower surface (convex surface) of the lens on the first stage (three concentric circles on the innermost circumference) of the lens tray. The lens is arranged so as to cover from the outside of the third stage to the outside of the third stage (lens arranged on the outermost concentric circle among the three concentric circles). The film thickness correction plate is attached to the wall surface on the plasma gun (plasma source 30) side. Introducing 150 sccm of dimethyldiethoxysilane and 363 sccm of oxygen as the monomer gas only in the lower film formation space, RF power is 6 kW, and the rotation speed of the lens tray is 20 revolutions per minute for 10 minutes only on the lower surface (convex surface) of the lens. Plasma CVD film formation was performed.
[0027]
[Example 2]
Plasma CVD film formation was performed by removing only the film thickness correction plate under the same film formation conditions in Example 1 above.
[0028]
As a result, comparative data shown in the following Table 1 was obtained. Regarding the lens arrangement in Table 1, the first, second, and third stages from the center side of the lens tray are used. This also applies to Tables 2 and 3 below. As is apparent from Table 1, in Example 1 with a correction plate and Example 2 without a correction plate, the film thickness of the thin film formed on each of the first, second, and third lenses is remarkable. There are significant differences. In Example 1 using the film thickness correction plate, the difference in film thickness between the first to third stages is smaller. Furthermore, from the viewpoint of the film formation rate, the difference in film formation rate between the first stage and the third stage is smaller in Example 1 using the film thickness correction plate.
[0029]
[Table 1]

[0030]
[Example 3]
In the same manner as in Example 1, the convex surface of the lens is set downward in the film formation chamber, the film thickness correction plates are attached to both the upper surface side and the lower surface side, and then the upper surface side film formation space and the lower surface side film formation are performed. In both spaces, 150 sccm of dimethyldiethoxysilane and 450 sccm of oxygen are introduced simultaneously as the monomer gas, the RF power is 6 kW, and the rotation speed of the lens tray is 20 revolutions per minute. Plasma CVD film formation was performed.
[0031]
[Example 4]
Under the same conditions as the film formation conditions in Example 3 above, only the upper and lower film thickness correction plates were removed to perform plasma CVD film formation.
[0032]
As a result, comparative data shown in the following Table 2 and Table 3 were obtained. Table 2 shows comparative film thickness data, and Table 3 shows concave film thickness comparison data. As is apparent from Tables 2 and 3, in Example 3 with the correction plate and Example 4 without the correction plate, the thin film formed on the first, second, and third lenses. There are significant differences in thickness. In Example 3 using the film thickness correction plate, the difference in film thickness between the first to third stages is smaller. Further, from the viewpoint of the film formation rate, the difference in film formation rate between the first stage and the third stage is smaller in Example 3 using the film thickness correction plate.
[0033]
[Table 2]

[0034]
[Table 3]

[0035]
【The invention's effect】
As is apparent from the above description, according to the present invention, when a thin film is formed on both surfaces or one surface of an optical lens base material using a plasma CVD method in a plasma CVD film forming apparatus, Since the film thickness correction mechanism is attached by arranging the film thickness correction plate in a predetermined positional relationship with respect to the optical lens base material disposed in the optical lens base material, the film thickness of the CVD film on the surface of the optical lens base material can be made uniform, A good film thickness distribution can be realized. In particular, in the case where a large number of optical lens base materials are arranged in a concentric positional relationship in the substrate holder, the difference in film thickness of the CVD film formed on the surface of the optical lens base material located on the inner side and the outer side is reduced, The film thickness distribution in a plurality of optical lens base materials in a lot with the substrate holder (lens tray) as a unit can be made uniform.
[Brief description of the drawings]
FIG. 1 is an internal configuration diagram of a main part of a plasma CVD film forming apparatus provided with a film thickness correcting mechanism according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a longitudinal sectional view showing a positional relationship between an arrangement state of a plastic base material in a substrate holder and a film thickness correction plate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Plastic base material 12 Substrate holder 13 Vacuum processing chamber 16 Shield plate 17, 27 Exhaust port 18, 28 Reaction gas supply source 19, 29 Reaction gas supply pipe 20, 30 Plasma source 41, 42 Film thickness correction plate

Claims (2)

In a film thickness correcting mechanism for plasma CVD film formation, which is used in a film forming apparatus for forming a thin film on the surface of an optical lens substrate by plasma CVD, and includes a film thickness correcting plate for correcting the film thickness difference of the thin film ,
The surface of the optical lens base material has a curvature, and a plurality of the optical lens base materials are arranged in a circular plate holder placed horizontally and in a rotating state, in a concentric position in a horizontally placed state,
The film thickness correction plate is disposed at a position away from the holder between the plasma source and reaction gas supply pipe outlet and the optical lens base material in a direction connecting the peripheral edge and the center of the holder. A mask member for adjustment,
A film thickness correction mechanism for plasma CVD film formation. Wherein the thin film is formed on the upper and lower surfaces of the optical lens base material, said mask member is the thickness correction mechanism for the plasma CVD film formation according to claim 1, characterized in that it consists of an upper mask member and a lower mask member.

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