JPS63210278A - Laser cvd device - Google Patents

Abstract

PURPOSE:To form a thin film having a uniform film thickness quickly on a large-area substrate, by providing a control member over the substrate to be treated so that the distribution of the film forming speed of a decomposed reactive gas on the substrate is narrowed. CONSTITUTION:The control member 2 is provided above the substrate 4 to be treated and an aperture 14 thereof is directed to the substrate 4 at the time of decomposing the reactive gas in a space by a laser beam 3 and forming the thin film on the substrate 4. This member 2 is constituted of decomposing chambers 2a, 2c having a U-shaped section and a supporting plate 2e and a gaseous raw material introducing pipe 12 is provided to the chamber 2c. the gaseous raw material is introduced through the pipe 12 into the chamber 2c, is supplied through an introducing port 1 into the chamber 2a and is decomposed by a laser beam 3, by which the thin film is deposited on the substrate 4 in this constitution. The substrate 4 is scanned by moving a substrate holder 5 in an arrow 15 direction at this time. The distribution of the film forming speed is thereby narrowed and the thin film having the uniform film thickness is formed on the substrate 4 in the short treatment time without being affected even if film forming conditions change.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention is directed to laser CVD (Chemical VD).
The present invention relates to a method for forming a thin film using the apordeposition method.

[Conventional technology]

Equipment for performing laser CVD is, for example, H, A
OKI, H., Yamazaki, J.Sh.
i rafuj i ;Proceedings o
fSymposium on Dry Process
;p, 132 (November 17-18, 1986). Figure 2 shows the laser CV shown in the above document.
It is a schematic diagram of D apparatus. In the figure, 21 is a laser, 22 is a vacuum chamber, 23 is a reaction gas injection member, 24 is a window made of quartz glass, 25 is a heater, 26 is a Pirani gauge, 2
8 is a flow meter, 29a, 29b, 29c are mass meters.
It is a flow controller.

When forming SiN (silicon nitride film) using this apparatus, NH3 and Si2H6 are used as source gases. The laser 21 used is usually an AF excimer laser,
It oscillates light with a wavelength of 193 nm. Decomposition of the source gas occurs only within the spatial region irradiated by the laser beam, and this is transported to the wafer to form the S--N film. Therefore, the area where the film is formed is limited to the vicinity through which the laser beam passes. Currently, the beam diameter of available A and F excimer lasers is about 25#x5, so 5in.
In order to form a film with a uniform thickness on a wafer having a ch diameter or a 6:nch diameter, it is necessary to scan the wafer or the laser beam perpendicularly to the direction in which the laser beam travels. This scanning width is a factor that determines the time required for film formation.

According to the inventor's study, when using the apparatus shown in Fig. 2, the scanning width, that is, the scanning distance, for forming a film at a uniform film formation rate within a wafer depends on the film formation rate distribution near the laser beam. It depends a lot. When attempting to scan a wafer and deposit a film on a 6-inch wafer with a uniformity of ±2.5% under the deposition conditions with the deposition rate distribution shown in Figure 3, approximately 22
It is necessary to scan a width of cm. Although the film forming conditions shown in Figure 3 are typical, the film forming rate distribution changes depending on the film forming conditions. There will be. Assuming that the deposition rate distribution near the laser beam is a Gaussian distribution, the scanning width required to deposit a film on a 6-inch wafer with a uniformity of ±2.5% as a function of the width is calculated as shown in Figure 4. become. As shown, the required scanning width increases by approximately 1.3 times the half-width due to the increase in the half-width.

[Problem to be solved by the invention 3 As mentioned above, conventionally used laser CV
Although it is possible to uniformly form a thin film on a 5-inch or 6-inch wafer, which is currently used in silicon processes, by scanning the wafer or laser beam using the D device, the suitable scanning distance varies depending on the film forming conditions. , the equipment must be adjusted to accommodate this, the scanning distance must be optimized for each film formation condition, and it is necessary to scan to the area where there is no wafer, so it is difficult to deposit a film on the wafer. There are drawbacks such as the lack of speed.

The present invention eliminates the above-mentioned drawbacks and provides a laser CVD apparatus that is not affected by changes in film-forming conditions and can form a thin film of uniform thickness on a wafer with a shorter scanning distance. The purpose is to

[Means for solving problems]

The laser CVD apparatus of the present invention includes a substrate holder that holds a substrate to be processed in the vacuum chamber, a means for supplying a reaction gas to the substrate to be processed on the substrate holder, and a means for supplying a reaction gas to the substrate to be processed, the reaction gas reaching the substrate to be processed. A laser CVD apparatus comprising a laser that generates a laser beam in order to cause the laser beam to pass through a space previously passed through, and a laser CVD apparatus that causes a reaction gas decomposed in the space by the laser beam to reach and deposit on the substrate to be processed. The method includes a limiting member for narrowing the film formation rate distribution on the substrate to be processed by the decomposed reaction gas.

[For production]

With the above configuration, the limiting means suppresses the spread of the film formation rate distribution, so even if the film formation conditions change, the scanning range can be made smaller, and therefore the processing time can be shortened.

〔Example〕

The overall configuration of the laser CVD apparatus according to one embodiment of the present invention is substantially the same as that described with reference to FIG. 2. However, as shown in FIGS. 1 and 5, the apparatus of this embodiment differs from the one shown in FIG. 2 in that it includes a control member 2. 1 and 5, FIG. 1 is a side view with respect to the traveling direction of the laser beam 3, with the vacuum chamber 7 as a cross section, and the substrate holder 4 and heater 6 inside the chamber 7.
, the restriction part vJ2, and the raw material gas introduction pipe 12 are shown. Further, FIG. 5 is a sectional view taken along the line V--V in FIG. 1. Furthermore, 8
is a window material that transmits laser beam 3, 9 is a laser,
10 is an inlet for a purge gas to prevent fogging of the window material, and 11 is a vacuum exhaust port.

As shown in FIGS. 1 and 5, the limiting member 2 of this embodiment has an opening 14, which is connected to the substrate 4 to be processed.
The laser beam 3 is disposed toward the substrate 4 to be processed, and is formed in a channel shape that surrounds a substantially columnar space 13 through which the laser beam 3 passes, together with the substrate 4 to be processed. That is, in the illustrated example, the restriction member 12 has a decomposition chamber 2a having a cross-section shaped like a cross-section, and a cross-section having a cross-section shaped like a cross-section communicating with the decomposition chamber 2a through the gas inlet 1 provided on the upper plate 2b of the decomposition chamber 2a. It has a decomposition chamber 2C. The lower end of the wall 2d of the decomposition chamber 2a is connected to a support plate 2e, which extends parallel to the left and right sides in FIG. 5 and is fixed to an inner wall (not shown) of the vacuum chamber 7.

The left and right ends of the decomposition u2a in FIG. 1 are open to allow the laser beam 3 to pass therethrough.

The left and right ends of the flow dividing chamber 2G in FIG. 1 may be open if the restriction member 2 is sufficiently longer than the substrate 4 to be processed as shown in FIG. 1, but they are kept closed. It is preferable.

The gas introduction pipe 12 is connected to a part of the upper plate 2f of the flow dividing chamber 2G.

The raw material gas introduced through the introduction pipe 12 is transferred to the branching chamber 2C.
It expands in its longitudinal direction, that is, in the left-right direction in FIG.

The substrate 4 to be processed is scanned by moving the substrate holder 5 laterally, that is, in the direction indicated by the arrow 15 in FIG.

Hereinafter, the effect of the limiting member 2 will be described when a silicon nitride film is formed on a silicon substrate using the above-mentioned apparatus.

An ArF excimer laser was used as the laser.

The laser light intensity was 200 mJ per pulse and 5 seconds per second.
It was repeated 0 times. The beam size of the laser light is 8#
It is X22#. The raw material gases are NH3 and S+2H6,
The flow rates are 130 cc/min and 3.3 cc/min, respectively.
Ar gas for purging was flowed at a rate of 300 CC/min, and the total pressure was set to 130 Pa by adjusting the exhaust speed. The substrate was heated to 300°C. This condition is the same as in the case of FIG.

The positional relationship between the limiting member 2, the laser beam, and the substrate is the sixth
I did it as shown in the figure. The seventh example compares the film formation rate distribution near the laser beam with that in the case where there is no limiting member 2.
It is a diagram. The half width of the distribution is 52. without the restriction member 2.
What used to be 5# became 25#, and due to the restriction member 2, the distribution changed from a glass type to a distribution with less widening of the hem.

Furthermore, the film formation rate at the peak was increased by about 25% compared to the case without the restriction member. Under these conditions, an experiment was conducted in which a film was formed on a 6-inch channel 3i substrate with a uniform film thickness of ±2.5%. Without the restriction member 2, the scanning width of the wafer was approximately 22 cm, but with the restriction member 2, the scanning width was only approximately 17.5 cm, and the film formation rate was
It was found that the current was 246 A/min when there was no restriction member, but when the restriction member 2 was installed, it increased by 33% to 327 A/min. At this time, the wafer was scanned under the condition that the wafer was scanned in a direction perpendicular to the direction of incidence of the laser beam, with the wafer reciprocating once per minute in the left and right directions by 1/2 of the scanning width.

Above, we have described the case where a 3i NX film is formed from 3i2H6 and NH3 on a 3i substrate using an Ar F laser, but the same effect can be applied to any case where a thin film is formed by decomposing the source gas with a laser beam. It is.

Furthermore, the restricting member 2 is not limited to the shape and arrangement of the above embodiments, but can be modified in various ways, the cross-sectional shapes of which are shown in FIGS. 8 and 9.

Among these, the example shown in FIG. 8(a) has two walls 81 to restrict the dispersion of decomposed debris in the lateral direction.

In the example shown in FIG. 8(b), the limiting member 2 is constituted by a partition plate 82 that partitions the space through which the laser beam passes and the substrate to be processed, and has a slit 82a through which the decomposed gas passes. In the embodiment shown in FIG. 4, the lateral diffusion of the decomposed gas is restricted, whereas in the embodiment shown in FIG.
In example b), the diffusion of the decomposed gas itself is not restricted;
Instead, the extent of flow of decomposed gas to the substrate is regulated.

The example shown in FIG. 8(C) consists of only a single channel-shaped member 83, and the raw material gas is introduced from its longitudinal end.

In addition, if the laser beam does not pass near the surface of the substrate parallel to the substrate, but hits the substrate obliquely as shown in Figures 9(a) and (b), the laser beam may be formed into a cylindrical shape. By providing a limiting member 84 that surrounds the laser beam 3 and extends close to the surface of the substrate, the same effect as described above can be obtained.

Further, the plate-like members constituting the limiting member do not have to be integrally fixed to each other, and there may be some gap between them.

(Effects of the Invention) As described above, according to the present invention, since the film formation rate distribution is narrowed by the limiting member, even when trying to form a film with a uniform thickness on a large area substrate, it is possible to The scanning width can be made small. Therefore, the device can be made compact and the film forming time can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the inside of a vacuum chamber of a laser CVD apparatus according to an embodiment of the present invention, Fig. 2 is a schematic diagram showing the overall configuration of the laser CVD apparatus, and Fig. 3 is a film forming rate distribution according to a conventional method. Figure 4 shows the relationship between the half-width of the film-forming rate distribution and the scanning width necessary to obtain a uniform film thickness. 6 is a diagram showing an example of the dimensions of the limiting member shown in FIGS. 1 and 5, FIG. 7 is a diagram showing a film forming rate distribution according to the embodiments shown in FIGS. 1, 5, and 6, and FIG. and FIG. 9 are diagrams showing a modification of the limiting member. DESCRIPTION OF SYMBOLS 1... Gas inlet, 2... Limiting member, 3... Laser beam, 4... Substrate, 5... Substrate holder, 7
...Vacuum chamber, 9...Laser. The half price of the eight genus speed promulgation (Cm) Le 9 small, is scanning 0 and a half depending on the width of the width 4 April Figure 1/) V-V Garlic WiW afternoon 5th fruit 1 I 1 dimensions I Retsujuku 6 Diagram <a) (1C) 1, II P [Four rows of four colors of parts 6 Figure 6f: Wall section 62; Sha-kiri rough 62a/Slit 63: Nine first do side part Pak 64: Control ff Parts <a) 4-row fan of control v11 section forest, potato θ ya

Claims (1)

[Claims] 1. A vacuum chamber; a substrate holder for holding a substrate to be processed in the vacuum chamber; means for supplying a reactive gas to the substrate to be processed on the substrate holder; A laser that generates a laser beam is provided in order to cause the laser beam to pass through a space through which it passes before reaching the substrate to be processed, and the reactant gas decomposed in the space by the laser beam reaches the substrate to be processed. What is claimed is: 1. A laser CVD apparatus for depositing a film on the substrate, comprising: a limiting member for narrowing the distribution of film formation speed on the substrate to be processed by the decomposed reaction gas. 2. Claims characterized in that the limiting member is formed so as to surround, together with the substrate to be processed, a substantially columnar space through which the laser beam passes, in order to limit the diffusion of the decomposed reaction gas. The device according to paragraph 1. 3. The apparatus according to claim 2, wherein the limiting member has a reactive gas inlet on a side facing the substrate to be processed. 4. A patent characterized in that the restriction member is a partition member that partitions a space through which the laser beam passes and the substrate to be processed, and has a slit that restricts passage of the decomposed reaction gas. An apparatus according to claim 1.