JPH11172447A - Plasma treating device and production of optical parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treating device capable of forming a coating excellent in plane uniformity, small in pinholes and local defects and excellent in coating properties. SOLUTION: This plasma treating device is the one having a vessel 101 permitting evacuation, a gas supply means 103 for supplying a gas for exciting plasma into the vessel, an exhausting means 102 for exhausting the inside of the vessel and a microwave feeding means feeding microwaves into the vessel and applying surface treatment to a body to be treated. The microwave feeding means has plural microwave radiators 200, and the face opposite to the body to be treated is directed in a prescribed direction corresponding to the face to be treated in the body to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus suitable for surface treatment of an optical component having a non-planar surface to be processed, such as a convex lens, a concave lens, a concave mirror, etc., and a technique for manufacturing an optical component using the same. Belongs to the field.

[0002]

2. Description of the Related Art There is a need for a technique for performing a surface treatment such as cleaning or film formation on an object having a non-planar surface.

A typical example is formation of an anti-reflection film on a convex lens.

Conventionally, as disclosed in JP-A-2-23267, a film is formed by a PVD method such as sputtering.

[0005] Since the PVD method is inferior in coverage on a surface having irregularities, the present inventors have tried to form a film by a CVD method.

[0006] Thermal CVD is not suitable in terms of thermal deformation of an object to be processed, and optical CVD is not sufficient in terms of throughput.

In order to obtain a film having a higher transmittance (lower absorptivity) and superior light resistance and environmental resistance than the antireflection film obtained by the PVD method at present, plasma excitation using a 13.56 MHz RF power source is required. CVD (PE-CVD) is also insufficient, and must be PE-CVD that can provide a higher density plasma.

As a PE-CVD capable of obtaining a high-density plasma of 10 ¹⁰ cm ⁻³ or more, there is an electrodeless PECVD using a microwave such as electron cyclotron resonance CVD (ECR-PECVD).

FIG. 7 shows a plasma processing apparatus described in JP-A-6-216047.

This apparatus includes a plasma generation chamber 2 and a processing chamber 4, in which microwave power introducing means 5, 6, 8 and a magnetic field applying means 10 are installed. Gas introduction system 20 is connected,
A chemical reaction material gas introduction system 22 is connected to the processing chamber 4, and an RF power introduction unit 18 is connected to the sample stage 14. The microwave power generation source 8 and the RF power generation source 18 are connected to the processing stage 4. On the other hand, a control device 27 for modulating each power is provided. The RF power and the microwave power are modulated in synchronization with each other, and the condition in which the film formation is prioritized and the condition in which the sputter etching is prioritized are alternately repeated.
A VD film is formed.

[0011]

When an antireflection film is formed on a convex lens using the apparatus shown in FIG. 7, a dense film can be formed on average, but the film has poor in-plane uniformity.

Further, there is a high probability that the reaction by-products stay near the surface to be processed, resulting in pinholes in the film or a film having a locally different composition ratio.

An object of the present invention is to provide a plasma processing apparatus capable of forming a coating having excellent in-plane uniformity and having less pinholes and local defects and excellent coating properties.

[0014]

In order to achieve the above object, a plasma processing apparatus according to the present invention comprises a container capable of reducing pressure and a gas supply for supplying gas for exciting plasma into the container. Means, an exhaust unit for exhausting the inside of the container, and a microwave supply unit for supplying a microwave to the inside of the container, wherein the microwave processing apparatus performs a surface treatment on an object to be processed. The supply means has a plurality of microwave radiators, and the surface of the object facing the object is oriented in a predetermined direction corresponding to the surface of the object.

Here, it is preferable that the microwave radiator has an antenna formed of a conductive flat plate having a number of slots.

A method of manufacturing an optical component according to the present invention includes a step of coating the optical component using the above-described plasma apparatus.

[0017]

FIG. 1 is a schematic sectional view showing an embodiment of a plasma processing apparatus according to the present invention.

Reference numeral 101 denotes a vacuum vessel which can be decompressed.
It is configured so that the pressure can be reduced to about 10 ^-6 Pa to 133 Pa.

The container 101 is provided with a large number of gas supply ports 103, such as UHF, SHF, EHF such as microwaves.
A gas which becomes a plasma by the high frequency energy of the band is introduced from here.

Further, a holder 104 for placing and holding the object to be processed W is provided in the container 101, and is vertically movable so that the vertical position thereof can be appropriately selected. It can rotate. Holder 10
4, a bias potential can be applied. Then, the holder driving mechanism 105 vertically moves and rotates the holder 104.

Reference numeral 200 denotes a microwave radiating member, and 201 denotes a sealing material between the microwave radiating members, which is made of ceramic or the like. 115 is an O-ring.

A gas introduced from a gas introduction port 107 connected to a gas supply system (not shown) is supplied from the gas supply port 103 into the plasma process space A via a gas supply passage 108 in the dielectric 202.

In the present embodiment, it is assumed that the surface of a lens having a convex spherical surface is processed as an object to be processed.

FIG. 2 is a top view of the microwave supply means used in the apparatus of FIG.

The microwave supply means is constituted by integrating five rectangular microwave radiating members 200 as shown in FIG.

FIG. 3 is a cross-sectional view taken along the line A′A ′ in FIG. 2 and shows a cross section of one microwave radiating member 200.

Reference numeral 211 denotes a conductor plate antenna having a number of slots. The inner conductor 110a of the coaxial waveguide 110 is connected near the center of the conductor plate antenna 211, and the outer peripheral end of the conductor plate antenna 211 is connected to the coaxial waveguide 11
0 is covered with a conductor cover 215 connected to the outer conductor 110b.

A microwave permeable dielectric plate 210 is arranged on the microwave radiating surface side of the conductor plate antenna 211, and a dielectric 212 is also arranged on the back surface of the conductor plate antenna 211 as necessary. The dielectric 212 is an antenna 211
They may be in contact with each other or a space may be interposed between them. As the dielectric plate 210, alumina, quartz, aluminum nitride (AlN), calcium fluoride, magnesium fluoride, or the like is used.

FIG. 4 shows a slotted conductor plate antenna 21.
FIG. 2 is a plan view of FIG. 1 in which a number of slots 211S are provided in a concentric or spiral shape.

Such an antenna is called a radial line slot antenna and is disclosed in Japanese Patent Application Laid-Open No. 1-184923, US Pat. No. 5,034,086, or Japanese Patent Application Laid-Open No. 8-1.
No. 11,297, JP-A-4-48805, JP-A-5-22025, and the like.

The distance Tg between the microwave radiating surface of the microwave radiating member 200 and the object to be processed W is substantially constant within a certain allowable range, for example, 10 mm to 50 mm.

The introduction of microwaves is as follows.

A microwave generated by a microwave oscillator (not shown) propagates through the coaxial tube 110 and passes through the conductor plate antenna 2.
Propagate to 11.

Microwaves propagated from a number of slots provided in the antenna 211 are radiated.

Next, the operation of forming a thin film on a spherical lens using the apparatus of the present invention will be described.

A convex lens is arranged and fixed on a holder 104 in the apparatus so that the surface to be processed faces upward.

The holder 104 is raised by the driving mechanism 105, and the object-supplying surface 106a of the microwave supply means is turned on.
The ascent is stopped at a position where the distance Tg between the substrate and the surface Wa to be processed becomes 10 mm to 50 mm.

After the pressure in the container 101 is reduced to about 1.3 × 10 ⁻⁵ Pa by an exhaust pump connected to the exhaust port 102, the processing gas is supplied from a gas supply system connected to the gas inlet 107 to a gas supply passage. It is introduced into the plasma process space A through 108. The pressure in the container is controlled from 13.3 Pa to 1.33 × 10 ³ by controlling the gas supply amount and the exhaust amount.
Maintain an appropriate pressure selected from Pa. Coaxial tube 11
Microwaves are supplied from a microwave oscillator connected to the conductor plate antenna 211 through the coaxial tube 110.

Thus, a glow discharge is generated in the plasma process space, and a gas plasma is generated. At this time, the plasma density is as high as 10 ¹¹ to 10 ¹³ cm ^-3 , and a dense and high-quality film can be formed.

Further, according to this embodiment, even when microwaves are used, the interval Tg of the process space is 10 cm or less (in this embodiment, 10 g).
cm less than 50mm)
The reaction by-product generated in the space A can be exhausted and removed at high speed. Therefore, a high-quality film with few pinholes can be formed.

FIG. 5 is a graph showing the relationship between the interval Tg between the dielectric 210 and the workpiece W and the plasma density. If the Tg is less than 10 mm, the plasma density will change greatly even if the interval is slightly different, and if the Tg exceeds 50 mm, the plasma density will drop sharply. If the inflection point is in the range of 10 mm <Tg ≦ 50 mm, the relative density difference of the plasma falls within 20%, and as a result, a uniform film can be formed.

FIG. 6 shows a microwave radiating member 200 and a workpiece W of a plasma processing apparatus according to another embodiment of the present invention.
The relationship is shown.

An adjusting means 201a for varying the angle α of the microwave radiating members is provided between the adjacent microwave radiating members 200. The adjusting means 201a has a telescopic bellows or a diaphragm, and an O-ring or the like is arranged at the boundary of the radiating member 200 so as to maintain airtightness. A space 214 for cooling the antenna is formed between the conductor plate antenna 211 and the dielectric 210. 2
Reference numerals 16 and 217 denote members for pressing and fixing the dielectric 210, and are made of a dielectric.

By adjusting the angle α and further raising and lowering the position of the holder 104, the interval Tg is set to 10 mm to 5 mm.
Adjust so that it falls within the range of 0 mm.

According to this embodiment, a surface treatment can be applied to a plurality of types of convex lenses having different radii of curvature.

The apparatus of the present invention can be used not only for the surface treatment of a spherical lens having a convex surface but also for the surface treatment of a spherical lens having a concave surface. In that case, a microwave supply means having an antenna with an inverted concavo-convex shape may be used.

Examples of the object W to be treated in the present invention include an insulating light-transmitting member made of quartz, fluorite, etc., and a conductive non-light-transmitting member such as aluminum. The former is a convex lens, It is used as a concave lens, a reflection mirror, and a window member, and the latter is used as a reflection mirror.

The surface treatment performed by the apparatus of the present invention includes formation of a thin film, plasma cleaning, and plasma etching. In particular, the device of the present invention is advantageous for forming a thin film, specifically, aluminum oxide, silicon oxide,
The formation of tantalum oxide, magnesium oxide, aluminum fluoride, and magnesium fluoride films.

Since the thin film is formed by plasma CVD,
The source gas used is trimethyl aluminum (TM
A), triisobutylaluminum (TiBA), organic aluminum compounds such as dimethyl aluminum hydride (DMAH), _{or, SiH 4, Si 2 H 6} , S
iF ₄ , a silicon compound such as tetraethylorthosilicate (TEOS), or an organic compound of magnesium such as tantalum or bisethylcyclopentadienyl magnesium. Further, in addition to these source gases, it is desirable to use an oxidizing gas such as oxygen, nitrogen oxide, fluorine, and NF _{3. If} necessary, a gas such as hydrogen, helium, neon, argon, xenon, or krypton is added. May be.

As a microwave oscillator, 2.45 GHz
An ordinary microwave oscillator having a frequency of 5.0 GHz, 8.3 GHz, or the like is used.

[0051]

EXAMPLE A convex lens made of quartz whose surface was polished into a spherical shape was arranged and fixed on a holder 104 of the apparatus shown in FIG.

The holder 10 is operated by operating the drive mechanism 105.
4 was raised, and the holder 104 was fixed at a position where Tg was 20 to 30 mm. After the interior of the aluminum container 1 was once evacuated to 1.3 × 10 ⁴ Pa and decompressed, the holder 104 was rotated. TM vaporized as processing gas
A and O ₂ were introduced, the pressure was set to 13.3 Pa, and microwaves were supplied to generate gas plasma. Thus, an aluminum oxide film was formed on the spherical convex surface of quartz.

[0053]

As described above, according to the present invention,
An optical component having a concave or convex surface to be processed can be uniformly processed using high-density microwave plasma.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a plasma processing apparatus according to the present invention.

FIG. 2 is a top view of a microwave supply unit.

FIG. 3 is a cross-sectional view taken along line A′A ′ of FIG. 2, showing one microwave radiating member.

FIG. 4 is a plan view of a slotted conductor plate antenna.

FIG. 5 is a diagram showing the relationship between the distance between the microwave radiating means and the object to be processed and the plasma density.

FIG. 6 is a sectional view of a plasma processing apparatus according to another embodiment of the present invention.

FIG. 7 is a sectional view of a conventional plasma processing apparatus.

[Explanation of symbols]

 Reference Signs List 101 vacuum vessel 102 exhaust port 103 gas supply port 104 holder 105 driving mechanism 107 gas introduction port 108 gas supply path 110 coaxial tube 115 O-ring 200 microwave radiating member 201a adjusting means 210 dielectric plate 211 conductor flat plate antenna 211s slot 212 dielectric 214 Space A Plasma process space W Workpiece

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyoshi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masaki Hirayama 52 Funacho, Wakabayashi-ku, Sendai City, Miyagi Prefecture 103 Pansion Aihara (72) Inventor Tadahiro Omi 2-1-17- 301 Yonegabukuro, Aoba-ku, Sendai, Miyagi

Claims (3)

[Claims] A container capable of reducing pressure, a gas supply means for supplying a gas for exciting plasma into the container, an exhaust means for exhausting the inside of the container, and a microwave in the container. And a microwave supply unit that supplies a surface of the object to be processed, wherein the microwave supply unit includes a plurality of microwave radiators and faces the object to be processed. A surface to be processed is oriented in a predetermined direction corresponding to the surface to be processed of the object to be processed. 2. The plasma processing apparatus according to claim 1, wherein the microwave radiator has an antenna formed of a conductive flat plate having a number of slots. 3. A method for manufacturing an optical component, comprising a step of coating an optical component using the apparatus according to claim 1.