JPS59219464A - Vapor phase chemical reaction method - Google Patents

Abstract

PURPOSE:To form a film of a reaction product having uniform film quality and thickness on the surface of a wafer by curving the showering surface in a reaction chamber, and injecting the 2nd gas to effect reaction while subjecting the 1st gas to a plasma discharge. CONSTITUTION:The bottom surface of a showering part 4 in a reaction chamber 1 is curved in such a way that the spacing H0 in the central part between the part 4 and a wafer 5 is large and that the spacings H1, H2 in the peripheral part are small. While the 1st gas such as H2 introduced into the chamber 1 is subjected to a plasma discharge, the 2nd gas such as SiH4 introduced through an introducing pipe 3 is injected from the part 4. The 1st gas and the 2nd gas introduced below the part 4 along the circumference on the side surface of the part 4 from the inside of the chamber 1 are brought into reaction and the reaction product such as Si2Ny is deposited on the surface of the wafer 5. The nonuniformity of the film quality in the radial direction of the wafer 5 is eliminated by the above-mentioned method.

Description

[Detailed Description of the Invention] This invention provides a gas phase chemical reaction method using plasma discharge,
In particular, it relates to a method for producing plasma nitride.

The plasma nitride generation method uses plasma discharge to react Si (silicon) with N and (nitrogen) in the gas phase to produce a S r x N y compound (S t ) on a Si wafer. This is a device that forms xNy (silicon nitrate) films, etc., and the device that performs this is generally an LFE in which only one Si wafer is installed in the reaction chamber.
(Company name) AM that can install molds and several wafers at the same time
Although there is a T (company name) type, we will mainly focus on the former here. For example, such technology is disclosed in Japanese Patent Application Laid-Open No. 51-8
It is described in Publication No. 9384 and the like.

For LFE type plasma nitride generation, for example, with reference to FIG.
and a shower part 4 having a gas introduction pipe 3 in the center, and a high frequency coil (frequency 13.56 M) around the container.
Hz) to generate a plasma discharge in the container, and the 5IH4 (monosilane) discharged from the shower reacts with the N2 introduced from the surroundings and turned into plasma, causing the S on the wafer mounting table 2 to react.
The reactant S i 3N4 is deposited on the i-wafer 5 .

Therefore, the reaction between Si and N2 mainly takes place in the reaction section 6 between the shower and the wafer mounting table.

A shower is generally a disc-shaped hollow container that is connected to a gas introduction pipe at the center of the top, and has many small holes in its bottom surface. It is attached.

A conventional shower has a flat shower surface as shown in FIG. 2(a).

By the way, nitrogen N'', l'J2* excited in container 1
etc. enter the reaction section from the side of the shower as shown in the drawing.
Because contact begins from the periphery of the wafer, the deposition of reactants on the wafer surface causes nonuniform film quality in the radial direction. For example, as shown in FIG. A ``Si-rich'' nylide film containing many components was formed.

As mentioned above, during the reaction, the reaction state of 5iHn and N2* changes between the Ueno/periphery and the center, and since S iH4') is present in the center, a relative depletion of N occurs. , a Si-rich nitride film is formed in some areas. The inventor of the present application believes that the above phenomenon is caused by N on SiH4.
We believe that the non-uniformity of the 2* and N* concentrations is the cause, and we have devised the present invention to improve this problem.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for producing a film with non-uniform film quality in the radial direction of a wafer, and with varying film quality and film thickness, in an LFE type plasma CVD apparatus.

To achieve the above object, the present invention has a wafer mounting table and a part of the shower facing each other in a plasma reaction chamber, and a first gas introduced (-) into the reaction chamber of the upper blade of the shower part is connected to (-) plasma discharge. While doing so, a second gas is injected from a part of the shower, and the second gas is mixed with the first gas introduced into the upper blade of the shower part from the reaction chamber of the upper blade of the shower part and around the side of the part of the shower. This is a device that causes a chemical reaction to deposit a reactive substance on the wafer surface on the wafer mounting table, and the shower surface is curved so that the distance between the shower part and the wafer surface is far from the center and close to the periphery. It is characterized by = and consists of.

Hereinafter, a detailed explanation will be given along with examples.

Referring again to FIG. 1, the shower surface (lower surface) of the Java part 4 into which 5iHa is introduced is changed from the conventional flat surface to a curved surface. That is, as shown in FIG. 2(b), between the shower part 4 and the shower head 5, the distance H6 at the center is made larger and the distance H6 at the periphery is made smaller. A part of the bottom of the shower forms a curved surface that is convex upwards.
Referring to the figure, the height H from the shower surface to the shower surface is changed as a function of the radius r (H(r)).

Plasma CVD of the present invention having such a shower part
Using a device, SiH4 was injected from a part of the shower, and N'' and N2* excited by a plasma reaction were introduced (,
A S r x N y film is deposited on the wafer surface during the S IH4+ N 2 *-8x N y reaction.
Although it changes depending on the H4/N2 ratio, total pressure, RF' (high frequency) output, etc., the distance H between the shower surface and the Ueno surface is an important parameter.

In general, the higher the S I H2/N2 ratio (the lower the total pressure, the lower the RF high output, the lower the H power)
There is a relationship that the larger the Si component is, the larger the Si component is.

Even if these parameters are changed, S in the radial direction r is generally
+Distribution is relatively conserved. [Above] Parameter φ, H
can be changed relatively easily in the radial direction, and H can be changed to r
By making it a function of , it is possible to compensate for changes in the concentration of N introduced from the surroundings. That is, the tendency of Si-richness at the center is corrected by increasing H at the center and reversing the direction of N-richness.

Figure 5 shows that in S i x N y deposited on the wafer surface, the x/y ratio generally decreases as H increases, and Figure 6 shows that it decreases as the distance r from the center increases. Show that.

Figure 7 shows each x when considering H as a function F(r), F when F is upwardly convex, F2 when F is a plane, and F3 when F is downwardly convex. / The curves of y and r are shown respectively.If F is made convex upward, that is, the distance between the shower surface and the Ueno surface is large at the ψ center,
This shows that a uniform Si compound film can be formed when the shower surface is formed so that it becomes smaller at the periphery.

Note that the constant value of x/y can be controlled as desired by pressure and RF output.

The present invention is not limited to the above embodiments, and various other embodiments are possible.

For example, by reacting O7 with SiH4,5iC-L, etc.,
The present invention can be applied to many cases where high temperature reactants are reacted using low temperature plasma, such as when obtaining a 5in2 film.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a plasma CVD apparatus showing the basic structure of the present invention, and FIG. 2 is a sectional view of a part of the shower. , FIG. 3 is a plan view showing the Si-rich portion of the wafer, FIG. 4 is a diagram for explaining the distance between the shower surface and the wafer surface, and FIGS. 5 and 6 are the relationship between the silicon distribution amount and H. , also r
FIG. 7 is a curve diagram showing the relationship between the silicon distribution amount and r when the shape of the shower surface is changed. DESCRIPTION OF SYMBOLS 1... Reaction container, 2... Wafer mounting stand, 3... Gas introduction pipe, 4... Part of shower, 5... Wafer, 6
...Reaction area, silicon-rich portion of silicon compounds deposited on the wafer. Agent Patent Attorney Akira Takahashi Mistake 1 Figure 2 Figure 3 Figure □ and

Claims (1)

[Scope of Claims] 1. In a gas phase chemical reaction apparatus having a Weno-mounting table in a plasma reaction chamber, a first gas is introduced into the plasma reaction chamber, plasma discharge is performed on the first gas, and A gas phase in which a second gas is introduced into the plasma reaction chamber separately from the first gas, and a chemical reaction is caused between the first gas and the second gas to deposit a reactant on the wafer surface on the wafer mounting table. Chemical reaction methods. 2. The first gas is nitrogen, and the second gas is 5iH4 (
monosilane) and S 1xNy on the silicon wafer surface.
The gas phase chemical reaction method according to claim 1, wherein a reactant is precipitated.