JPH05345978A - Device for forming thin film - Google Patents

Abstract

PURPOSE:To perfectly prevent the contamination of the wall and window of a reaction chamber by the sticking of a reactional product, to improve reproducibility and to enable continuous film formation by concentrating a reactive component on a part, near a substrate. CONSTITUTION:A flow guard member 13 with many flow guard plates 15 arranged parallel to the axial lines of many small holes in a gas blast member 11 at regular intervals is disposed under the gas blast member 11. The thickness distribution of a formed thin film can directly be controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus such as a CVD or photo CVD apparatus.

[0002]

2. Description of the Related Art As an example of a conventional thin film forming apparatus, Japanese Patent Publication No. Sho 63-7619 discloses a CVD apparatus. As shown in FIG. 4 of the accompanying drawings, this apparatus has a nozzle B for ejecting a reaction gas, which is a first gas, on one side wall of a vacuum chamber A.
Is provided, and the ejection nozzle B is connected to an external reaction gas supply source (not shown) via a conduit C. Further, a hollow inert gas ejection portion F having a large number of small holes is provided on the upper wall of the vacuum chamber A so as to face the substrate E on the susceptor D arranged in the vacuum chamber A. An exhaust port G is provided at a position on the bottom wall of the vacuum chamber A opposite to the reaction gas ejection nozzle B. The reaction gas is introduced from the conduit C through the reaction gas jet nozzle B in a sheet shape substantially parallel to the surface of the substrate E in the vacuum chamber A, and the inert gas as the second gas is in the upper part of the vacuum chamber A. Substrate E from inert gas spout F
It is introduced in the direction toward the side and acts so as to maintain the reaction gas in the laminar flow state near the surface of the substrate F as shown by hatching. The reaction gas and the inert gas thus introduced are discharged through the exhaust port G.

In such a gas flow system, an inert gas flow introduced so as to face the substrate suppresses the rise of the reaction gas in the vicinity of the substrate and also serves to prevent turbulent flow and diffusion of the components of the reaction gas. As a result, the gas component of the first gas flow is suppressed only in the vicinity of the substrate, and it is possible to prevent the contamination that the film adheres to the wall of the vacuum chamber, the viewing window, etc .; And is excellent in controllability and reproducibility; there is an advantage that the film thickness distribution on the substrate can be controlled by controlling the flow rate of the second gas flow. A particular advantage has been used as a method for preventing the contamination of the light transmission window in a photochemical vapor deposition apparatus (hereinafter simply referred to as a photo CVD apparatus) in which the contamination of the optical window is a problem among the CVD apparatuses. An example thereof is shown in FIG.

In the photo CVD apparatus shown in FIG. 5, a light transmission window H made of synthetic quartz for transmitting ultraviolet light or vacuum ultraviolet light is provided on the upper wall of the vacuum chamber A, and ultraviolet light or ultraviolet light is provided outside the window. A light source chamber K is provided which includes a light source I that emits vacuum ultraviolet light and a reflection plate J that prevents loss of light emitted from the light source I. Further, on the inner surface of the light transmission window H, an inert gas ejection portion F made of a synthetic quartz plate having a large number of small holes facing the substrate E on the susceptor D arranged in the vacuum chamber A.
Is provided. Similar to the case of the CVD apparatus in FIG. 4, the first gas (reaction gas) is introduced from an external conduit C through a reaction gas ejection nozzle B in a sheet shape substantially parallel to the surface of the substrate E in the vacuum chamber A. Further, the inert gas is introduced from the inert gas jetting portion F in the upper part of the vacuum chamber A in the direction toward the substrate E side, and the reaction gas as the first gas is maintained near the surface of the substrate F in a laminar flow state. Is acting like. The reaction gas thus introduced is decomposed by the ultraviolet light or vacuum ultraviolet light emitted from the light source I, and a desired film is deposited on the surface of the substrate E. In this case, if the inert gas which is the second gas is not introduced from the inert gas jetting portion F above the vacuum chamber A, the inert gas jetting portion F and the light transmission window H are instantaneously supplied.
The reaction product adheres to the substrate and impedes the transmission of the light emitted from the light source I, making it impossible to form a film. However, a second gas flow of a certain flow rate or more is passed from the inert gas jetting portion F to the substrate E. By introducing the gas in the direction toward the side, the reaction gas is pressed into the vicinity of the substrate E as described above, and is less likely to diffuse into the inert gas ejection portion F or the light transmission window H. As a result, the contamination of the inert gas ejection portion F, the light transmission window H and the like during the film forming operation can be suppressed to some extent.

[0005]

By the way, such a thin film forming apparatus using the conventional gas flow system is effective in a relatively short film forming process on an experimental machine level, but is a production apparatus level apparatus. When a film is formed for a long period of time, the contamination of the inner wall of the vacuum chamber and other parts of the vacuum chamber with reaction products becomes an important problem. In particular, in the case of a photo-CVD apparatus, it is impossible to completely prevent the film from adhering to the light transmission window, and continuous film formation for a long time is impossible. For example, how much the light transmission window is contaminated when an a-Si: H (hydrogenated amorphous silicon) film is formed for 1 hour by a conventional photo CVD apparatus using a gas flow method is described as follows. Ratio Ia of light intensity on substrate before film formation
When expressed as / Ib, Ia / Ib = 0.3, and it was confirmed that a considerable amount of reaction product was attached to the light transmission window compared to Ia / Ib = 1 when the light transmission window was not contaminated at all. Be done. This is the first ejected from the slit-shaped opening.
Of the reaction gas, that is, the reaction gas, is insufficiently suppressed by the second gas, that is, the inert gas, that is, when the inert gas spouts through the small holes of the inert gas spouting portion, it faces downward immediately after spouting, The flow toward the substrate collapses and has a direction toward the exhaust port as shown in FIG. 4, so that the function of suppressing the diffusion of the first gas toward the light transmission window side is weakened. In addition, there is sufficient reaction gas in the upper wall of the vacuum chamber other than the inert gas spouting part, and the fact that these reaction gases are entrained in the inert gas spouted from the inert gas spouting part is also a pollution factor. Is considered one of the.

Therefore, the present invention solves the problems associated with the conventional gas flow system, and concentrates the reaction components only in the vicinity of the substrate, thereby completely preventing the contamination of the reaction products on the reaction walls and windows. However, it is an object of the present invention to provide a thin film forming apparatus which is reproducible and is capable of continuous film formation.

[0007]

In order to achieve the above object, according to the present invention, a first gas flow is introduced in a sheet shape substantially parallel to the surface of a substrate arranged in a closed tank. A thin film forming apparatus which introduces a second gas flow into the surface of the substrate from a direction perpendicular to the surface to maintain the first gas flow in a laminar flow state in the vicinity of the surface of the substrate. In the above, a gas ejection member having a large number of small holes for introducing the second gas flow is provided at a position facing the surface of the substrate, and under the gas ejection member, parallel to the axis of each small hole in the gas ejection member. The present invention is characterized in that a flow guard member provided with a large number of flow guard plates which extend at a distance from each other is provided. The flow guard member may be configured to have a gradually decreasing height along the direction of the first gas flow.

[0008]

In the thin film forming apparatus of the present invention thus constructed, a large number of gas ejecting members for the second gas extend parallel to the axis of each small hole in the gas ejecting member and are spaced apart from each other. By providing the flow guard member including the flow guard plate of the second gas, the second gas ejected from the gas ejecting member of the second gas is guided toward the substrate by the flow guard plate of the flow guard member and the substrate. A strong flow is created towards the flow path, and this flow guard member acts to prevent the first gas from wrapping around in the second gas flow. As a result, the generation and diffusion of the turbulent flow of the first gas can be effectively prevented, and the reaction products can be completely prevented from adhering to the inner wall of the vacuum chamber, the observation window, and the light transmission window.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 illustrates the present invention as a light C
An example applied to a VD device is shown. Illustrated light CV
In the apparatus D, 1 is a vacuum tank, that is, a reaction tank, in which a susceptor 2 having a variable temperature is provided, and a substrate 3 on which a film is grown is mounted on the susceptor 2. A nozzle 5 having a thin slit-shaped opening 4 for introducing a first gas, that is, a reactive gas, is provided on a side wall of the vacuum chamber 1, and the nozzle 5 is not shown via an external conduit 6 and is not shown. Is coupled to a gas source. The nozzle 5 is made of Al alloy and is positioned so that the first gas can be introduced substantially parallel to the surface of the substrate 3 on the susceptor 2. In the case of the mercury sensitization method, which is often used in the photo-CVD method, the Al alloy forming the nozzle 5 may react with mercury to generate dust. Moreover, the nozzle 5 may be subjected to an anodic oxide coating treatment. A light transmission window 7 made of synthetic quartz is provided on the upper wall of the vacuum chamber 1 at a position facing the substrate 3, and a light source 8 for emitting ultraviolet light or vacuum ultraviolet light and an ultraviolet light from the light source 8 are provided outside the light transmission window 7. A light source chamber 10 that accommodates a light or vacuum ultraviolet light and directs it onto the substrate 3 through the light transmission window 7 to prevent light loss is installed. Further, on the inner surface of the light transmitting window 7, a slight gap is formed between the inner surface of the light transmitting window 7 and the inner surface of the light transmitting window 7, and synthetic quartz is used.
A second gas-introducing jet portion 11 having a large number of small gas jet holes is provided, and a gap between the jet portion 11 and the inner surface of the light transmitting window 7 is outside the upper wall of the vacuum chamber 1. It is connected via an attached conduit 12 to a source of a second gas, an inert gas (not shown). Inert gas spouting part
A flow guard member 13 is attached to the lower side of 11.
The flow guard member 13 is configured by mounting a flow guard plate 15 made of a thin synthetic quartz plate in a flow guard frame body 14 at regular intervals, and each flow guard plate 15 is provided with a reaction gas from the nozzle 5. It is oriented so as to extend in a direction transverse to the flow direction and direct the inert gas ejected from the inert gas ejecting portion 11 downward toward the substrate 3 on the susceptor 2. Therefore, the height of each flow guard plate 15 in the flow guard member 13 can be arbitrarily set according to the inner size of the vacuum chamber 1 and the like. The flow guard member 13 is fixed to the inside of the upper wall of the vacuum chamber 1 together with the inert gas ejection portion 11. Furthermore, an exhaust port 16 is provided near one end of the bottom wall of the vacuum chamber 1 as shown in the figure.

The operation of the illustrated apparatus thus configured will be described below. The reaction gas is introduced from the external conduit 6 through the thin slit-shaped opening 4 of the nozzle 5 into a sheet shape substantially parallel to the surface of the substrate 3. The inert gas is introduced downward from the inert gas ejection portion 11 with respect to the flow of the sheet-like reaction gas. The downward flow of the inert gas is guided downward by the flow guard frame body 14 of the flow guard member 13 and each flow guard plate 15 toward the substrate 3, and the downward flow of the inert gas directed by the flow guard member 13 is directed. Due to the flow, the flow of the sheet-like reaction gas from the nozzle 5 is effectively suppressed in the vicinity of the substrate 3, so that the generation and diffusion of the introduced reaction gas turbulence is effectively suppressed, and as a result, the light transmission window 7. It is possible to completely prevent the reaction products from adhering to the surfaces of the gas ejecting part 7 and the inert gas jetting part 11, and to continuously operate the apparatus without devitrification of the light transmitting window 7 even during a long-time film forming operation. You can

In FIG. 2, aS is obtained by photodecomposition of SiH ₄ .
The change in the light intensity ratio Ia / Ib on the substrate before and after the film formation of the i: H film for one hour is shown in comparison with the conventional device. In the device according to the conventional technique, as shown in (a), Ia / Ib is about 0.3, whereas when only the flow guard frame 14 is arranged below the inert gas jetting portion 11, As shown in b), Ia / Ib is about 0.8, and when the flow guard plate 15 is arranged in the flow guard frame body 14,
As shown in (c), Ia / Ib = 1, and the light transmission window 7
It is also confirmed that the reaction product does not adhere to the surface of the inert gas jetting portion 11 at all. The degree of adhesion of the reaction product to the light transmitting window 7 depends on the distance h between the substrate 3 and the light transmitting window 7 and the flow rate Q of the inert gas blown out from the inert gas jetting portion 11. When the flow rate Q is 3.0 slm,
h is required to be> 75 mm.

FIG. 3 shows a modification of the flow guard member. In the apparatus shown in FIG. 1, the flow guard member is formed to have a uniform height over the entire area of the inert gas blowing region, but in the example shown in FIG. A configuration in which a large number of flow guard plates 18 having different heights are sequentially arranged along the inclination of the flow guard frame body 17 in the flow guard frame body 17 which is inclined along the flow direction, that is, the height of which gradually decreases. Is becoming With this configuration, in addition to controlling the film thickness distribution by adjusting the flow rate of the inert gas and the flow rate of the reaction gas ejected from the nozzle, it is possible to control the film thickness distribution more directly. ..

In the illustrated embodiment, the light source is installed in the atmosphere, but since the reaction product can be completely prevented from adhering to the light transmitting window according to the present invention, the light source may be installed in the vacuum chamber. it can. Further, although the illustrated apparatus relates to an optical CVD apparatus, the present invention is not limited to the optical CVD apparatus, and is applied to other film forming apparatuses such as a thermal CVD apparatus, a plasma CVD apparatus, a dry etching apparatus and the like. Therefore, it is possible to prevent film contamination on the reaction wall and the viewing window.

[0014]

As described above, according to the present invention, the first gas flow introduced in a sheet shape substantially parallel to the surface of the substrate arranged in the closed tank is provided near the surface of the substrate. The second gas flow introduced from the direction perpendicular to the surface of the substrate for maintaining the laminar flow state is provided with the flow guard member for directing the flow in the direction toward the substrate.
It is possible to prevent the first gas staying in the closed tank in which the gas is not ejected from flowing around, and to prevent undesired film-adhering contamination on the tank wall, the light transmission window, the peep window, etc. it can. As a result, not only the film quality can be improved and dust particles can be reduced, but also the film forming operation can be continuously performed for a long time without maintenance, and the present invention can be applied to a manufacturing process of a semiconductor device or an electronic device. Further, in addition to the control of the film thickness distribution by adjusting the flow rates of the first gas and the second gas, the flow guard member can more directly control the film thickness distribution.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a photo-CVD apparatus according to an embodiment of the present invention.

FIG. 2 is a graph illustrating an operation effect of the device of FIG.

3 is a perspective view showing a modified example of a flow guard member that can be used in the apparatus of FIG.

FIG. 4 is a schematic sectional view of a conventional CVD apparatus using a gas flow method.

FIG. 5 is a schematic sectional view of a conventional photo-CVD apparatus using a gas flow method.

[Explanation of symbols]

 1: Vacuum tank 3: Substrate 4: Thin slit-like opening 5: Nozzle 11: Second gas introduction spout 13: Flow guard member 15: Flow guard plate

Front page continued (72) Inventor Akitoshi Suzuki 2500 Hagien, Chigasaki City, Kanagawa Prefecture, Japan Vacuum Technology Co., Ltd.

Claims (2)

[Claims] 1. A first gas flow is introduced in a sheet shape substantially parallel to the surface of a substrate disposed in a sealed tank, and a second gas flow is introduced onto the surface of the substrate from a direction perpendicular to the surface. In order to introduce the second gas flow to the position facing the surface of the substrate in the thin film forming apparatus in which the first gas flow is maintained in the laminar state near the surface of the substrate by introducing A gas ejecting member having a large number of small holes is provided, and a flow is provided below the gas ejecting member with a large number of flow guard plates extending parallel to the axis of each small hole in the gas ejecting member and spaced from each other. A thin film forming apparatus comprising a guard member. 2. The thin film forming apparatus according to claim 1, wherein the flow guard member is configured such that its height is gradually reduced along the direction of the first gas flow.