JPH0714789A - Cvd equipment - Google Patents

Abstract

PURPOSE:To enhance the uniformity of film thickness without requiring modification of conditions having critical effect on the characteristics of film formation, e.g. temperature distribution, by arranging nozzles sparsely at the opposite end parts as compared with the central part. CONSTITUTION:Nozzles 8, 8,... at gas supply section 6, which are conventionally arranged uniformly over the entire length, are arranged sparsely at the opposite end parts as compared with the central part. Since gas supply per unit area is decreased at the opposite end parts, uneven thickness of VCD film caused by stagnation of exhaust gas can be corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CVD apparatus, and in particular, a process gas is ejected toward a lower wafer from a gas supply section in which a large number of nozzles are arranged, and is exhausted from the upper center of a reaction chamber. C so that a CVD film is formed on the surface
It relates to a VD device.

[0002]

2. Description of the Related Art As a normal pressure CVD apparatus, a process gas is ejected toward a lower wafer from a gas supply section in which a large number of nozzles are arranged and exhausted from the upper center of a reaction chamber to form a CVD film on the surface of the wafer. A CVD apparatus configured to form the film is known, and FIGS. 4A and 4B show such a normal pressure CV.
It is one of the prior art examples of D apparatus, (A) is a longitudinal cross-sectional view, (B) is a BB line plan view. In the drawing, 1 is a reaction chamber, 2 is a conveyor belt that moves on the bottom surface of the reaction chamber 1 and conveys the semiconductor wafers 3, 3.
It is heated to 0 ° C. An exhaust hood 4 has an opening at the center of its ceiling, and an exhaust pipe 5 communicates with the opening.

Reference numeral 6 denotes a gas supply section, which is a plurality of gas supply pipes 7.
a, 7b, 7c different gas (eg O ₂
A gas, N ₂ gas, SiH ₄ gas, etc.) is jetted downward from the nozzles 8, 8, ..., Which are provided on the bottom surface, specifically, onto the semiconductor wafers 3, 3. The arrangement density of the nozzles 8, 8, ... Is conventionally uniform over the entire length of the gas supply section 6. The gas supply unit 6 includes gas supply pipes 7a, 7b, 7c.
The different gases supplied from the above are jetted without being mixed inside, that is, while being separated. This is because the mixture of the gases is changed to the semiconductor wafers 3, 3,
The semiconductor wafers 3 and 3 as much as possible
The CVD film is formed only on the upper surface of the gas supply unit 6
This is to prevent vapor phase growth reaction from occurring inside.

Then, the gas injected downward toward the semiconductor wafers 3, 3 (3a is an orientation flat) reacts on the semiconductor wafers 3, 3 to form a CVD film, and at the same time, the semiconductor wafers 3, 3 are formed. Gas supply unit 6 from above
Both sides of the [upper and lower sides in FIG. 4 (B), FIG. 4 (A)]
The paper surface side and the paper spine side in [1], enter the exhaust hood 4, and are exhausted from the exhaust pipe 5 to the outside of the CVD apparatus.

[0005]

By the way, according to the conventional CVD apparatus shown in FIG. 4, the uniformity of the thickness of the CVD film is low as shown in FIG. Specifically, there is a problem that the thickness of the CVD film becomes thicker on both sides of the reaction chamber 1. As is apparent from FIG. 5, the film thickness is 580 to 590 nm near the central portion of the reaction chamber 1, but is 625 to 635 nm on both sides of the reaction chamber 1.

Upon investigating the cause of this, as a result of the exhaust being carried out in the central part of the reaction chamber 1, the exhaust at both sides of the reaction chamber 1 cannot be carried out as smoothly as in the central part, and therefore 9 in FIG. A stagnant flow as shown in FIG.
It was found that the phenomenon that the film thickness becomes thicker on the side of the reaction chamber 1 occurs. By the way, such nonuniformity of the film thickness cannot be overlooked. Therefore, it was attempted to increase the film thickness uniformity by providing a temperature gradient in a direction orthogonal to the wafer transport direction of the reaction chamber 1. Specifically, it has been attempted to make the temperature of both ends of the conveyor belt 2 lower than the temperature of the central part. However, this method cannot be adopted because it may adversely affect the characteristics of the CVD film (uniformity of impurity concentration, etc.).

The present invention has been made to solve such a problem, in which a process gas is ejected toward a lower wafer from a gas supply section having a large number of nozzles.
Evacuate from the upper center of the reaction chamber and CVD on the wafer surface.
It is an object of the present invention to improve the uniformity of film thickness in a CVD apparatus configured to form a film without changing conditions such as temperature distribution that have a significant effect on film formation characteristics.

[0008]

A CVD apparatus according to a first aspect of the present invention is characterized in that nozzles of a gas supply unit are arranged at a density lower at both end portions than at a central portion. The CVD apparatus according to a second aspect is characterized in that an exhaust path is also provided on both sides of the upper portion of the reaction chamber.

[0009]

According to the CVD apparatus of the first aspect, the arrangement density of the nozzles having the uniform film thickness is made sparser at both end portions than at the central portion. Therefore, the gas supply amount per unit area at both end portions is reduced. can do. Therefore, as shown in FIG. 2, it is possible to correct the nonuniformity of the thickness of the CVD film due to the accumulation of exhaust gas.

According to the CVD apparatus of the second aspect, since the exhaust passages are also provided at both upper side portions of the reaction chamber, it is possible to reduce or eliminate the accumulation by the exhaust passages. Therefore, it is possible to reduce or eliminate the nonuniformity of the thickness of the CVD film caused by the retention of the exhaust gas.

[0011]

The CVD apparatus of the present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 is a sectional view showing one embodiment of the CVD apparatus of the present invention. This embodiment is different from the conventional CVD apparatus shown in FIG. 4 in that the nozzles 8, 8, ...
Although the arrangement densities are different from each other, the other points are common, and the common parts have already been described, so the description thereof will be omitted and only the different points will be described.

In the gas supply unit 6 of the present CVD apparatus, the arrangement density of the nozzles 8, 8, ..., Which has been uniform over the entire length in the past, is made sparser at both end portions than at the central portion. . Therefore, according to the present CVD apparatus, the gas supply amount per unit area at both ends can be reduced,
As a result, as shown in FIG.
The non-uniformity of the film thickness can be corrected.

FIG. 2 is a sectional view showing another embodiment of the CVD apparatus of the present invention. This embodiment is the conventional CV shown in FIG.
The device D is different from the device D in that an exhaust path is also provided at both upper side portions of the reaction chamber, but is common in other points, and the common parts have already been described, and thus the description thereof is omitted. Only different points will be described.

The exhaust hood 4 of the present CVD apparatus is conventionally
The exhaust pipe 5, which was provided only in the central portion of the upper portion, is also provided in both side portions of the upper portion. The exhaust pipes 5a and 5a are provided on both sides of the exhaust pipe. Therefore, according to the present CVD apparatus, since the exhaust is performed only in the central portion of the reaction chamber 1, the stagnant that has occurred in both side portions of the reaction chamber 1 can be eliminated by the exhaust pipes 5a, 5a, and the exhaust is further extended. The nonuniformity of the film thickness of the CVD film caused by the retention of gas can be reduced or eliminated.

[0015]

According to the first aspect of the present invention, the CVD device is characterized in that the arrangement density of the nozzles having the uniform film thickness is made sparser at both end portions than at the central portion. Therefore, according to the CVD apparatus of the first aspect, the gas supply amount per unit area at both ends can be reduced. Therefore,
It is possible to correct the non-uniformity of the thickness of the CVD film due to the accumulation of exhaust gas.

The CVD apparatus according to a second aspect is characterized in that an exhaust path is also provided at both upper side portions of the reaction chamber. Therefore,
According to the CVD apparatus of the second aspect, it is possible to eliminate the accumulation that has also occurred at both upper side portions of the reaction chamber by the exhaust passage, and to eliminate it. Therefore, it is possible to reduce or eliminate the nonuniformity of the thickness of the CVD film caused by the retention of the exhaust gas.

[Brief description of drawings]

FIG. 1 is a sectional view showing one embodiment of a CVD apparatus of the present invention.

FIG. 2 is a film thickness distribution diagram of the CVD film of the above-mentioned embodiment.

FIG. 3 is a sectional view showing another embodiment of the CVD apparatus of the present invention.

4A and 4B show a conventional example of a CVD apparatus, FIG. 4A is a sectional view, and FIG. 4B is a plan view taken along line BB of FIG.

5 is a film thickness distribution diagram of a CVD film showing a problem of the conventional CVD apparatus shown in FIG.

[Explanation of symbols]

 1 Reaction Chamber 3 Wafer 5 Exhaust Pipe 5a Exhaust Pipe (Exhaust Path) 6 Gas Supply Section 8 Nozzle 10 CVD Film

Claims (2)

[Claims] 1. A process gas is jetted toward a lower wafer from a gas supply unit provided with a large number of nozzles and exhausted from the upper center of a reaction chamber to form a CVD film on the surface of the wafer. In the CVD apparatus, the arrangement density of the nozzles of the gas supply unit is made sparser at both end portions than in the central portion. 2. A process gas is jetted toward a lower wafer from a gas supply unit provided with a large number of nozzles and exhausted from the upper center of the reaction chamber to form a CVD film on the wafer surface. In the CVD apparatus, an exhaust path is also provided on both sides of the upper part of the reaction chamber.