JPS61208213A - Photochemical vapor deposition apparatus - Google Patents

Abstract

PURPOSE:To prevent contamination of the optically transparent member in the reaction chamber by flowing a reactive gas over the side of the material to be processed in the reaction chamber, and also passing a nonreactive gas over the surface side of the optically transparent member. CONSTITUTION:A semiconductor wafer 8 on which a thin film will be formed is so placed on the holding section 10 that the thin film forming side is directed to the reaction chamber 6, and the lid member 12 is mounted on the upper side 2 to realize a sealed state. Subsequently the light source 36 is driven to apply light to the heat storage member 18 via an optically transparent member 20 and keep the wafer 8 at a particular temperature. Then internal air of the chamber 6 is exhausted to introduce a reactive gas 64, first and second nonreactive gases 66, 68 into the chamber 6 and pass a laser light 93, followed by irradiation of the wafer 8 with light emitted from the light source 60. Then a particular thin film is formed on the surface of the wafer 8 as the result of the reaction of the gas 64 with the light 93 and the light emitted from the source 60. As the first nonreactive gas 66 passes at a high speed over the surface of the member 40, adhesion of dust to the surface of the member 40, which accompanies the photochemical vapor phase reaction, is inhibited and contamination is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical vapor phase epitaxy device used to form a thin film on the surface of a processed material such as a semiconductor wafer, and in particular, relates to an optical vapor phase epitaxy device used to form a thin film on the surface of a processing target material such as a semiconductor wafer. This invention relates to preventing stains on installed light transmitting members.

[Conventional technology]

For example, photoCVD (Chemical
In a vapor deposition system, a semiconductor wafer is placed in a reaction chamber, and a specific reaction gas is applied to the surface of the semiconductor wafer, and light of a specific wavelength is applied from outside the reaction chamber.

In such an optical CQD device, a light source is installed outside the reaction chamber, and a window is formed on the wall of the reaction chamber to guide light from the light source into the reaction chamber, and the window is made of a light-transmitting member such as quartz glass. It is shielded.

This light transmitting member becomes contaminated due to a photovapor phase reaction in the reaction chamber, and when its light transmittance decreases due to the contamination, this causes a change in the thickness of a thin film formed on a semiconductor wafer.

Conventionally, methods such as cleaning the surface of the light transmitting member or applying oil to the surface have been taken as measures against staining of such a light transmitting member.

[Problem that the invention seeks to solve]

However, cleaning the light transmitting member requires a considerable amount of time, which reduces the efficiency of the vapor phase growth process. Also,
The method of applying oil is advantageous in that it reduces the number of cleaning operations, but the short wavelength component of the reaction light is absorbed by the oil layer,
This causes a decrease in the photovapor phase growth rate, which also causes a decrease in the operation.

Therefore, the present invention aims to prevent the light transmitting member of the reaction chamber from becoming dirty.

[Means for Solving the Problems] That is, in the present invention, a light transmitting member is installed on the wall surface of a reaction chamber, and light from a light source is irradiated onto a material to be treated in the reaction chamber through the light transmitting member. The optical vapor phase growth apparatus is characterized in that a reactive gas is allowed to flow to the side of the material to be treated in the reaction chamber, and a non-reactive gas is allowed to pass to the surface side of the light transmitting member.

[For production]

Therefore, the present invention allows a reactive gas to flow through the side of the material to be processed such as a semiconductor wafer, and at the same time allows a high-speed non-reactive gas to pass through the reactive gas contacting surface side of the light transmitting member.
This prevents stains from adhering to the light-transmitting member due to a photovapor phase reaction involving a reactive gas.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the optical vapor phase growth apparatus of the present invention.

In FIG. 1, a reaction chamber 6 for optical vapor phase growth is formed by joining an upper member 2 and a lower member 4.

In this embodiment, a semiconductor wafer 8, for example, is used as the material to be processed, and the upper member 2 is formed with a holding part 1o that supports the semiconductor wafer 8. It is supported with the surface to be formed facing the reaction chamber 6 side.

A lid member 12 is installed above the upper member 2 so as to be separable from the upper member 2, and the semiconductor wafer 8 is attached or removed by opening and closing the lid member 12. The space between the upper member 2 and the lid member 12 is maintained in an airtight state by an O-ring 16 installed in the recess 14 on the upper surface of the upper member 2, and is also maintained in a pressure contact state by a pressure contact means (not shown). Ru.

A heat storage member 18 made of tungsten, graphite, etc. is attached to the center of the lid member 12 facing the semiconductor wafer 8 as a heating means for uniformly heating the semiconductor wafer 8 from the back side, and a heat storage member 18 made of tungsten, graphite, etc. is attached to the upper side of the heat storage member 18. A light transmitting member 20 made of the like is installed.

Between the heat storage member 18 and the light transmitting member 20, an opening 21 of the holding portion 10 of the upper member 2 is inserted from the side surface of the lid member 12.
A gas passage 23 is formed leading to the gas passage 2.
An inert gas 25 for preventing dirt from adhering to the light transmitting member 20 is passed through the reaction chamber 3 and led into the reaction chamber 6 .

A housing 22 for installing a heating light source is installed on the upper side of the lid member 12, and a recess 24.
It is sealed via the ○ ring 28.30 installed in 26, and is fixed by the fixing bolt 32.34,
A light source 36 is installed inside the light source housing 22.

A light irradiation window 38 for irradiating light onto the semiconductor wafer 8 is formed in the lower member 4, and this light irradiation window 38 is shielded by a light transmission member 4o made of quartz glass or the like.

Furthermore, a sealing frame 46 that supports O-rings 42 and 44 that maintain airtightness between the lower member 4 and the light transmitting member 40 is fixed to the lower member 4 with fixing bolts 48 and 50. A guide frame 54 of an opening/closing device 52 that opens and closes the transmission of light is attached to the lower side of this sealed frame 46, and a shielding plate 58 that is opened and closed by a plunger 56 is movable inside this guide frame 54. is attached to. A light source 60 that emits light of a specific wavelength is installed below the opening/closing device 52.

A reaction gas 64 supplied from a specific gas source, a first non-reaction gas 66 and a second non-reaction gas 68 made of an inert gas are individually supplied to the side wall of the reaction chamber 6.
Gas supply holes 70, 72, 74 are formed,
The opening of the gas supply hole 70, 72, 74 on the reaction chamber 6 side is provided with a hole for forming an independent laminar flow of the reaction gas 64 and the first and second non-reactive gases 66, 68 in the reaction chamber 6. A rectifying nozzle 76 is installed. The rectification nozzle 76 independently communicates with the gas supply holes 70.72.74 and supplies the supply gas 64.66.68 to the reaction chamber 6 to a pressure adjustment section 78 that adjusts the pressure of the supply gas 64.66.68. This is a combination of three injection parts 80 that independently inject into the air. The pressure adjustment section 78 has a passage 82 having the same diameter as the gas supply hole 70, 72, 74, and is expanded larger than the diameter thereof to form a pressure adjustment chamber 84, and adjusts the pressure of the supply gas 64, 66, 68. The flow rate is lowered by increasing the flow rate, and the flow rate is then supplied to the injection section 80. The injection unit 80 has a zero pressure in front of the pressure adjustment chamber 84 of the pressure adjustment unit 78.
．． It has multiple independent slits about the size of two fins.

Further, a rectifying nozzle 86 is installed on the gas outlet side of the reaction chamber 6, and a lower member 4 on the back side of the rectifying nozzle 86 increases the pressure of the flowing gas 64, 66, 68 to form a laminar flow. An inclined surface 88 rising on the downstream side of the gas
A discharge port 90 is formed on the terminal end side of this inclined surface 88 for merging and exhausting the respective gases 64, 66, and 68. An exhaust device such as a pump is connected to this exhaust port 90, and a constant exhaust pressure 92 is applied thereto.

A laminar flow of the reactant gas 64 and the first and second non-reacting gases 66 and 68 is formed inside the reaction chamber 6, and the flow has a specific wavelength in the direction perpendicular to the laminar flow. Laser light 93 is supplied. In this case, the reactive gas 64 grows a thin film on the semiconductor wafer 8 in association with the laser beam 93, and the first non-reactive gas 66 causes the light-transmitting member 4 to grow a thin film.
In order to prevent dust from adhering to the light transmitting member 4
The second non-reactive gas 68
is passed at a low speed in order to separate the reactive gas 64 and the first non-reactive gas 66.

FIGS. 2 and 3 show a single injection section 80 of the rectifying nozzle 76, which has multiple injectors 80 for independently injecting the reactant gas 64 and the first and second non-reacting gases 66,68. A rectangular slit 94 is formed, and rectifying pieces 96 are made to protrude from the upper and lower edges of this slit 94 toward the gas flow side. Note that 98 is a fixing hole.

Further, FIGS. 4 and 5 show a rectifying nozzle 86, in which a slit 100 having a larger interval than the slit 94 is formed and a similar rectifying piece 102 is provided. It is something.

Note that 104 is a fixing hole.

The operation will be explained based on the above configuration.

The lid member 12 is removed from the upper member 2 by an opening/closing means (not shown), and the semiconductor wafer 8 on which the thin film is to be formed is placed on the holding part 10 of the upper member 2 with the surface on which the thin film is to be formed facing the reaction chamber 6. placed. Then, the lid member 12 is attached to the upper member 2 and kept in a sealed state.

In this state, the light source 36 is driven, and the light from the light source 36 is irradiated onto the heat storage member 18 through the light transmission member 20.
Heat generated by the irradiation light is retained in the heat storage member 18. This heat preheats the semiconductor wafer 8, and the semiconductor wafer 8 is maintained at a specific temperature.

Next, while driving the light source 60, the air inside the reaction chamber 6 is removed, and the reaction chamber 6 is filled with the first and second reaction gases 64.
A non-reactive gas 66,68 is passed through the laser beam 93.
pass.

Then, the plunger 56 is pulled in the direction of arrow A, the shielding plate 58 of the opening/closing device 52 is opened for a specific period of time, and the semiconductor wafer 8 is irradiated with light from the light source 60. As a result, a specific thin film is formed on the surface of the semiconductor wafer 8 by the reaction gas 64, the laser beam 93, and the irradiation light from the light source 60.

In such optical vapor phase growth, first and second non-reactive gases 66 and 68 are placed in the reaction chamber 6 along with the reaction gas 64.
is supplied to each gas supply hole 70, 72, 74 independently from a specific gas source, and after the pressure is adjusted by the pressure adjustment part 78 of the rectification nozzle 76, it is supplied to the injection part 80, so that each gas is supplied independently from a specific gas source. It is supplied as a laminar flow with a certain flow. In this case, on the downstream side of the gas 64, 66, 68, an inclined surface 88 as a pressure adjustment part is provided together with a rectifying nozzle 86, so that a laminar flow is maintained on the downstream side due to the increase in pressure. That is, in the reaction chamber 6, a laminar flow is obtained in which the reaction gas 64 and the first and second non-reactive gases 66, 68 have mutually independent passages, and do not mix with each other.

Since the first non-reactive gas 66 passes through the surface side of the light transmitting member 40 at a high speed, the adhesion of dust accompanying the optical gas phase reaction to the surface of the light transmitting member 40 is prevented, and the light transmitting member 40 stains can be prevented.

As a result, a decrease in the light transmittance of the light transmitting member 40 can be suppressed, and variations in the thickness of the thin film formed on the semiconductor wafer 8 can be suppressed.

In the flow of the first non-reactive gas 66, a low-velocity second non-reactive gas 68 is interposed between the first non-reactive gas 64 and the reactant gas 64, and each gas 64,66 is
．． As a result, the first non-reactive gas 66 has no influence on the reactive gas 64, and a stable photo-vapor phase growth process can be realized.

In the embodiment, a semiconductor wafer was used as the material to be processed, but the optical vapor phase growth apparatus of the present invention can form a thin film on a metal material or other material to be processed other than the semiconductor wafer.

〔Effect of the invention〕

As explained above, according to the present invention, since a high-speed non-reactive gas flows in parallel with the reactive gas on the surface side of the light-transmitting member that guides light into the reaction chamber, dust adhesion to the light-transmitting member is prevented. This makes it possible to suppress the decrease in light transmittance, thereby suppressing fluctuations in film thickness formed on processing materials such as semiconductor wafers, and realizing stable and highly reliable photovapor phase growth processing. .

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the photovapor phase growth apparatus of the present invention, FIG. 2 is a plan view showing the first rectifying nozzle, and FIG. 3 is a sectional view taken along the line ■-■ in FIG. 2. , FIG. 4 is a plan view showing the second rectifying nozzle, and FIG. 5 is a sectional view taken along line V-V in FIG. 4. 6... Reaction chamber, 8... Semiconductor wafer as processed material, 40... Light transmitting member, 60... Light source, 64...
... Reactive gas, 66.68 ... Non-reactive gas, 76.8
6... Rectification nozzle, 78... Pressure adjustment section, 88...
- Inclined surface as a means of pressure adjustment.

Claims (3)

[Claims] (1) In a photo-vapor phase growth apparatus, a light transmitting member is installed on a wall surface of a reaction chamber, and light from a light source is irradiated onto a material to be treated in the reaction chamber through the light transmitting member. A photovapor phase growth apparatus characterized in that a reactive gas is allowed to flow to the side of the material to be processed, and a non-reactive gas is allowed to pass to the surface side of the light transmitting member. (2) The optical vapor phase growth apparatus according to claim 1, characterized in that a non-reactive gas is caused to flow between the reactive gas and the non-reactive gas. (3) A rectifying nozzle having a pressure adjustment means is installed in the gas supply section of the reaction chamber to supply the reaction gas and the non-reaction gas independently, and a pressure adjustment section is installed on the gas downstream side of the reaction chamber. 2. The optical vapor phase epitaxy apparatus according to claim 1, wherein the reactant gas and the non-reactive gas are provided with independent laminar flows.