JPH0660138U - Observation window in plasma CVD apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] A plasma CVD apparatus capable of blocking ultraviolet rays harmful to the eyes without fear of being clouded and difficult to see through even if the film forming vacuum container is cleaned with a fluorine-based gas plasma. Provide an observation window at. [Structure] A transparent sapphire plate 63 that does not react with fluorine and that is disposed at a position exposed in the film formation processing vacuum container 1
And an observation window 6 provided with a see-through Pyrex glass plate 65 that blocks ultraviolet light transmission and is arranged outside the plate 63 at intervals.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

The present invention is, for example, a plasma CVD (chemical) method for forming a silicon film (Si), a silicon dioxide film (SiO ₂ ), a silicon nitride film (SiN, Si ₂ N ₃ ) or the like on a substrate in a semiconductor device manufacturing process. Dynamic vapor deposition apparatus, it relates to an observation window provided in the vacuum container for visually observing the inside of the vacuum container for the film formation process.

[0002]

[Prior art]

In the plasma CVD apparatus, as described above, for example, a Si film, a SiN film, a SiO ₂ film or the like is formed on the semiconductor device substrate. A vacuum container for film formation is usually provided with an observation window for observing the inside of the container, and a Pyrex glass plate that shields ultraviolet rays harmful to the eyes is usually fitted into the window. .

In addition, a film is formed on the inner wall of the vacuum container and the parts inside the container by the film forming process, but when this film is deposited, it peels off and becomes so-called particles, which are mixed in the target film. Or, it adheres to the film surface and deteriorates the film quality. Therefore, as disclosed in, for example, Japanese Patent Publication No. 4-52612, a plasma of a fluorine-based gas, for example, a mixed gas of carbon tetrafluoride (CF ₄ ) and oxygen (O ₂ ) is used in the empty container. It is also practiced to regularly clean the vacuum container by dry etching.

[0004]

[Problems to be solved by the device]

 However, when cleaning the inside of the vacuum container with a fluorine-based gas plasma in this way, the Pyrex glass plate of the observation window reacts with this plasma and reacts, causing clouding, which makes it impossible to observe the inside of the container. is there. Therefore, the present invention has an observation window in a plasma CVD apparatus capable of blocking ultraviolet rays that are harmful to the eyes without the possibility that the inside of the vacuum chamber for film formation processing will be clouded and difficult to see through even if it is cleaned with a fluorine-based gas plasma, and it will not be impossible to see through. The challenge is to provide.

[0005]

[Means for Solving the Problems]

 The observation window of the present invention which solves the above-mentioned problems is an observation window provided in the vacuum container for visually observing the inside of the film forming vacuum container of the plasma CVD apparatus, and is exposed to the inside of the vacuum container. It is characterized in that it includes a transparent first member which is disposed at a position and does not react with fluorine, and a transparent second member which is disposed outside the member and is spaced apart from the transparent member and blocks ultraviolet light transmission.

The first member may be made of sapphire (Al ₂ O ₃ ), diamond (C), zinc sulfide (ZnS), fluorspar (CaF ₂ ), or the like. The second member may be made of Pyrex glass, acrylic resin, or the like. Among these, sapphire for the first member and Pyrex glass for the second member are relatively easily available materials.

The gap between the first member and the second member is for avoiding the occurrence of interference fringes due to the interference of light and the difficulty of observation due to the interference fringes that may occur when these members are brought into contact with each other and overlapped. This gap can be appropriately determined, but 0.1 mm or more is preferable in order to prevent the occurrence of interference fringes to the extent that there is no problem in observation.

[0008]

[Action]

 According to the observation window of the present invention, the first member that does not react with fluorine is disposed in the portion exposed to the fluorine gas plasma for cleaning in the film forming vacuum container, and the first member that may react with fluorine is disposed. Since the two members are arranged outside the first member and are not exposed to the plasma, there is no possibility that the observation window will be difficult or impossible to be transparent due to cleaning with the fluorine-based gas plasma.

Even if ultraviolet rays, which are harmful to the eyes, may pass through the first member during observation inside the container, the ultraviolet rays are blocked by the second member, which is safe. In addition, since the first member and the second member are arranged at a distance without being in close contact with each other, interference fringes due to light interference that may occur when they are in close contact with each other are not formed, so that the inside of the vacuum container can be neatly cleaned. Can be observed.

[0010]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of a plasma CVD apparatus adopting an embodiment of the present invention. This plasma CVD apparatus comprises a vacuum processing container 1, in which a holder 2 also serving as an electrode on which a film-forming target substrate S such as a semiconductor device substrate is mounted and an upper electrode 3 above it are arranged. . Usually, the holder 2 is grounded and the electrode 3 is a high frequency electrode. Further, the container 1 is provided with a gas introduction part 4 and a vacuum exhaust device 5 is connected thereto.

An observation window 6 according to the present invention for observing the inside of the container 1 is provided on a part of the side wall 11 of the container 1. The window 6 is provided with an O-ring fitting groove 61 surrounding the through hole 11a provided in the side wall 11 and surrounding the hole, and an O-ring 62 for airtight sealing is fitted into the O-ring fitting groove 61 so as to contact the O-ring. A see-through Pyrex glass plate 65 is applied to the member through a spacer ring 64 having a thickness of 0.1 mm or more, and a cushioning material is applied from the outside. A pressing ring 67 is applied via 66, and the pressing ring 67 is fixed to the container wall 11 with a screw 68.

According to this plasma CVD apparatus, the substrate S to be film-formed is set on the holder 2 and is exhausted from the container 1 by the evacuation device 5 so that a predetermined film-forming vacuum degree is maintained, The film-forming gas is introduced from 4, and high-frequency power is applied between the electrodes 2 and 3, whereby the introduced gas is turned into plasma, and the substrate S is exposed to the plasma to form a film thereon. It During the film forming process, the inside of the container 1 can be observed through the observation window 6.

At the same time in this film forming process, the film formed on the inner wall of the container 1 and the components inside the container 1 is removed by dry etching cleaning the inside of the container. In this cleaning, when the film to be formed is, for example, a SiN film or a SiO ₂ film, a fluorine-based gas (for example, a mixed gas of CF ₄ and O ₂ ) as a cleaning gas is introduced from the gas introduction part ₄ and the container 1 The inside of the chamber is maintained at a predetermined etching vacuum degree by operating the exhaust device 5, and high-frequency power is applied between the holder 2 and the upper electrode 3 to plasma the gas, and the fluorine-based gas plasma does not require the above-mentioned unnecessary gas. This film is removed by dry etching by exposing the film.

During this cleaning process, the observation window 6 is exposed to the fluorine-based gas plasma. According to the observation window 6, a sapphire plate 63 that does not react with fluorine is arranged in the portion exposed to the plasma, and Since the Pyrex glass plate 65 that reacts with fluorine is arranged outside the sapphire plate 63 and is not exposed to plasma, there is no possibility that the observation window 6 becomes difficult or impossible to see through cleaning with fluorine-based gas plasma.

Even if ultraviolet rays, which are harmful to the eyes, may pass through the sapphire plate 63 during observation inside the container, the ultraviolet rays are sufficiently shielded by the Pyrex glass plate 65, which is safe. Further, since the sapphire plate 63 and the Pyrex glass plate 65 are arranged so as not to be in close contact with each other with a space therebetween, interference fringes due to light interference that may occur when they are in close contact with each other are not formed, so that the vacuum container 1 can be refreshed. You can observe inside.

[0016]

[Effect of device]

 As described above, according to the present invention, there is no fear that even if the vacuum chamber for film formation is cleaned with a fluorine-based gas plasma, it will not become cloudy or difficult to see through, and plasma CVD that can also block harmful ultraviolet rays to the eyes. An observation window in the device can be provided.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a plasma CVD apparatus adopting an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum processing container 11 Side wall 11a of container 1 Through hole of side wall 6 Observation window 61 O-ring fitting groove 62 O-ring 63 Sapphire plate 64 Spacer ring 65 Pyrex glass plate 66 Cushioning material 67 Pressing ring 68 Set screw

Claims (2)

[Scope of utility model registration request] 1. A reaction window with fluorine, which is an observation window provided in the vacuum container for visually observing the interior of the vacuum container for plasma deposition of a plasma CVD apparatus, and which is located at a position exposed in the vacuum container. Plasma C characterized by including a see-through first member and a see-through second member that is disposed outside the member and is spaced apart from the member and that blocks UV transmission.
Observation window in VD device. 2. The observation window in the plasma CVD apparatus according to claim 1, wherein the first member is made of sapphire, and the second member is made of Pyrex glass.