JPS62263629A - Vapor growth device - Google Patents

Abstract

PURPOSE:To form a uniform thin-film onto the surface of a wafer by shaping a raw gas supply nozzle in constitution in which the quantity of a raw gas fed to the peripheral section of the wafer is made more than that fed in the central direction of the wafer. CONSTITUTION:The quantity of a raw gas supplied to the peripheral section of a wafer is made more than the quantity of the raw-material gas caused to flow substantially in parallel with the surface of the wafer in the plural and fed in the central direction of the wafer in H2 gas containing an Si raw gas. A waste gas after used for epitaxial growth is evacuated to the outside of a bell jar 3 by an exhaust nozzle 7. Epitaxial layers having desired film thickness are formed on the surfaces of the wafers, the supply of the Si raw gas from a gas supply nozzle 6 is stopped, purging by H2 gas is conducted, heating by a high-frequency coil 5 is suspended, and the temperature of a susceptor 4 is lowered. Accoridngly, the film thickness of the epitaxial layers shaped onto the wafers having a large diameter can be equalized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for forming a vapor phase growth layer on the surface of a semiconductor wafer, and particularly for forming a vapor phase growth layer uniformly on the surface of a large number of semiconductor wafers. The present invention relates to a vapor phase growth apparatus.

[Conventional technology]

In the semiconductor manufacturing process, SiO2 films and nitride films (SiaN4) are deposited on semiconductor wafers using vapor phase chemical reactions.
CVD (Chemical Vapor Deposit) to form polycrystalline silicon films, single crystal silicon films, etc.
tion) technology is widely applied. Among these, single crystal silicon film formation is particularly called epitaxial growth.

In recent years, the diameter of semiconductor wafers has been increasing in order to reduce process costs and improve product yields, and wafers with a diameter of 125 to 150 mm are now becoming mainstream.

On the other hand, in order to reduce process costs, efforts are being made to increase the number of wafers that can be processed at one time in various apparatuses, that is, the number of wafers that can be charged when performing batch processing.

In CVD apparatuses as well, wafer diameters are becoming larger and wafers are being processed in larger quantities. On the other hand, as devices become more highly integrated and operate at higher speeds, highly accurate uniformity of the thin films formed is also required.

JP-A-59-59 as a CVD device that meets the above requirements.
A device as shown in Japanese Patent No. 878 has been proposed.

In this method, the wafers are arranged with their surfaces perpendicular and arranged at equal intervals and housed in a reaction vessel, and the wafers are uniformly heated by a heating means installed outside the reaction vessel and substantially surrounding the entire vessel, and the reaction gas is heated. It is introduced into the reaction vessel through a conduit and uniformly supplied to each wafer from above the wafer through a nozzle.

The purpose of this method is to form a uniform CVD thin film on a large number of wafers at once by discharging waste gas from an exhaust port provided below the wafer.

[Problem that the invention seeks to solve]

The above-mentioned conventional vapor phase growth apparatus has the drawback that it is difficult to obtain sufficient uniformity in the in-plane film thickness distribution of a large diameter wafer in response to the demand for more precise film thickness uniformity.

An object of the present invention is to provide a vapor phase growth apparatus that can form a thin film with a uniform thickness distribution even on large diameter wafers.

[Means for solving problems]

The above purpose is to increase the number of raw material gas flows supplied from the raw material gas supply nozzle to the wafer surface, and to increase the amount of raw material gas supplied to the periphery of the wafer than the amount of raw material gas supplied toward the center of the wafer. This is achieved by

Specifically, for example, among the plurality of gas injection holes or gas injection slits provided in the source gas supply nozzle, the number of gas injection holes or gas injection slits that inject source gas toward the wafer periphery is increased by the number of gas injection holes or gas injection slits that inject source gas toward the wafer center. The size of the gas injection hole or the width of the gas injection slit that injects the source gas toward the wafer periphery may be increased to the size that injects the source gas toward the center of the wafer. This can be achieved by making it larger than the pod width.

In addition, the gas flow rate and gas injection hole (or slit width) can be determined individually.
A plurality of independently adjusted raw material gas supply nozzles may be provided at optimal locations in the furnace to supply the raw material gas as described above.

[Effect]

The center of the wafer is constantly supplied with raw material gas from the gas supply nozzle, while the periphery of the wafer receives only intermittent supply due to the rotation of the wafer.

By supplying a larger amount of source gas than the center, the amount of growth can be increased when source gas is intermittently supplied to the periphery of the wafer, so the film thicknesses at the center and periphery can be made approximately the same. A uniform film thickness distribution can be obtained.

〔Example〕

The present invention will be explained below using Si epitaxial growth as an example.
This will be explained in detail with reference to FIGS.

As shown in FIG. 1, a large diameter wafer 1 with a diameter of 150 m is
The holder 2 is charged in multiple stages in a stacked state separated from each other, and the holder 2 is rotated to rotate around the center of the wafer 1. After creating an H2 gas atmosphere inside the bell jar 3, the temperature of the susceptor 4 is raised to 1100° C. by the high frequency coil 5.

H2 gas containing 81 source gases is supplied from the gas supply nozzle 6 to form a Si nipitaxial layer on the surface of each wafer 1. At this time, the H2 gas containing the Si raw material gas is
As shown in the figure, a plurality of raw material gases are flowed substantially parallel to the wafer surface, and the amount of raw material gas supplied to the periphery of the wafer is larger than the amount of raw material gas supplied to the inside of the wafer in the jQ'' direction.

The waste gas after being used for epitaxial growth.

The exhaust nozzle 7 exhausts the air outside the venter 3.

After an epitaxial layer with a desired thickness is formed on the surface of the wafer 1, the supply of Si raw material gas from the gas supply nozzle 6 is stopped, and after purging with N2 gas, heating by the high frequency coil 5 is stopped, and the susceptor 4 is The temperature drops.

According to the above apparatus, the thickness of the epitaxial layer formed on a large-diameter wafer can be made uniform.

Next, specific numerical examples will be explained. First, two wafers 1 each having a diameter of 125 mm are placed back to back on the holder 2, and a total of 50 wafers are set in 25 stages with an interval of 10 mm between them, and charged into the bell jar 3. While rotating the wafer holder 2 at 25 rpm, Nz gas is supplied into the bell jar 3 from the gas supply nozzle 6 to replace the air in the furnace. In order to supply the gas, gas injection holes 6o are provided in sets of five gas injection holes 6o at intervals of 10 m in the vertical direction, one more set than the number of stacked wafers, 5 x 26 sets, 130 in total. What is the size of the gas injection hole 60?

As shown in FIG.
The one facing the direction shifted by °) has a diameter of 5no, about 30mm.
The one facing in the direction shifted by (θz230') has a diameter of 7 m.

Stop the N2 gas, and while flowing N2 gas at a flow rate of 30 Q/min, energize the high-frequency coil 5 and heat the susceptor 4 to 1100°C. 6 When the susceptor 4 reaches a predetermined temperature, add zero,
5 mo 9% HCQ gas is mixed and the wafer surface is
Min W'A, phase etch 1. ．． To start. At this time, the amount of gas supplied from the nozzle 6 and above should be reduced to a large extent around the wafer, so uniform etching must also be achieved.

After stopping the HCQ gas and running the gas page for 2 minutes,
1.5 moQ% of S i CQ 4 was mixed in Hz.

Start epitaxial growth. 10 in 20 minutes of growth
After forming an epitaxial layer of μm.

Stop mixing 5iCQa, and purge the source gas with Nz gas for 2 minutes.

Gradually reduce the energization of the high frequency coil 5 to 400 in about 15 minutes.
After cooling the susceptor 4 to ℃, the power is turned off. After cooling with N2 gas for 15 minutes, the inside of the furnace is replaced with N2 gas, the bell jar 3 is opened, and the wafer 1 is taken out.

According to the above experimental example, the thickness distribution of the epitaxial layer formed on a wafer with a diameter of 125 mm can be made uniform.

In this embodiment, epitaxial growth of silicon is taken as an example, but it is also applicable to other CVD methods in which a thin film is formed by rotating around the wafer center and supplying gas parallel to the wafer surface. Furthermore, although the embodiment has been described with the wafers stacked in multiple stages, the present invention can also be applied to the case of a single wafer. Furthermore, it goes without saying that the injection hole through which the source gas is injected may be a vertical slit instead of a hole.

Note that the deviation angle θ in the gas injection direction (θ=01°θ2...
...) and the size of the gas injection hole or the width of the slit must be corrected based on the wafer rotation speed, gas flow rate, injection speed, etc., and the amount of correction is determined experimentally.

In addition, as another example, as shown in FIGS. 3 to 5, each of the individual gas flow rates (or concentrations) and gas injection holes (or slit widths) arranged y4 can be used to supply a plurality of raw material gases. The nozzles 6A to 6E may be provided inside the furnace.

〔Effect of the invention〕

According to the present invention, the variation in the thickness of the vapor-phase grown layer within the wafer can be reduced to 1/4 or less compared to the conventional case of supplying the vapor-phase growth layer toward the center of the rotating wafer, and a uniform thin film can be formed on the wafer surface. It becomes possible to form.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing one embodiment of the vapor phase growth apparatus of the present invention, FIG. 2 is a sectional view of the main part of FIG. 1 explaining the present invention in detail, and FIGS. FIG. 7 is a sectional view of a main part showing another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Wafer, 2... Wafer holder, 3... Belljar, 4... Susceptor, 5... Heating coil, 6...
Gas supply height 1z Line 2 Diagram 3,,,' Tsuji S diagram et al. Person Y≧No person IshiE 1-t”strategy non-ζgo1shi

Claims (1)

[Claims] 1. The wafer is rotated around its center as a rotation axis, and a raw material gas is supplied from a raw material gas supply nozzle substantially parallel to the wafer surface from the outer circumferential direction of the wafer, and a vapor phase chemical is applied to the wafer surface. A vapor phase growth apparatus for forming a thin film by reaction, characterized in that the source gas supply nozzle is configured such that the amount of source gas supplied to the periphery of the wafer is greater than the amount of source gas supplied toward the center of the wafer. vapor phase growth equipment. 2. In claim 1, among the plurality of gas injection holes or gas injection slits arranged in the source gas supply nozzle and from which source gas is injected, those facing the periphery of the wafer are A vapor phase growth apparatus characterized by having more than one facing the center. 3. In claim 1, the size of the gas injection hole or the width of the gas injection slit on the peripheral side that is arranged in the raw material gas supply nozzle and from which the raw material gas is injected is
A vapor phase growth apparatus characterized in that the size of a gas injection hole or the width of a gas injection slit is larger than that of a gas injection hole that injects source gas toward the center of a wafer. 4. A vapor phase growth apparatus according to any one of claims 1 to 3, characterized in that the wafers are housed in a wafer holder in a multi-stage stacked state. 5. In claims 1 and 2, a plurality of independent source gas supply nozzles are provided, each of which has its gas flow rate (or concentration) and gas injection hole (or slit width) adjusted individually. A vapor phase growth apparatus characterized by: