JPH04139719A - Vapor growth device - Google Patents

Abstract

PURPOSE:To prevent a decline in the film growth rate of a vapor growth device by efficiently resolving or activating a gaseous starting material in a limited area between discharge electrodes in a reaction chamber by light energy and electric energy arriving at the area. CONSTITUTION:RF electrodes 24a and 24b across which a high-frequency voltage is applied from an RF power source 10 which gives electric energy to a gaseous starting material are formed to ring-like plate electrodes having an inside diameter nearly equal to the outside diameter of a reaction chamber 1 and held at positions on both sides of a substrate 8 in the reaction chamber 1 at an interval wider than the width of the substrate. Then thermal energy from a light source 5A arrives at the gaseous starting material without being interrupted by the electrodes 24a and 24b and efficiently heats the starting material and, at the same time, plasma 15 is formed in a limited area around the substrate 8 by the electric energy supplied from the power source 10. Therefore, the gaseous starting material is efficiently resolved and forms a thin film on the surface of the substrate 8.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention combines a thermochemical reaction or photochemical reaction using light energy and a discharge decomposition reaction using electrical energy to combine both reactions on the surface of a substrate. The present invention relates to a vapor phase growth apparatus for forming rI41IK.

[Conventional technology]

In recent years, in order to improve film quality (film density, internal stress, etc.) and film formation characteristics (film thickness distribution, film formation speed, etc.), thin film formation technology that combines conventional thin film formation methods has been researched. Along with this, research on equipment to promote this composite thin film formation technology is also progressing.

FIGS. 4 and 5 show examples of the structure of a conventional vapor phase growth apparatus that combines a thermochemical reaction using light energy and a discharge decomposition reaction using electrical energy.

The apparatus shown in FIG. 4 includes a transparent reaction chamber 1 made of a heat-resistant dielectric material such as quartz glass, and formed into an elongated cylindrical shape with an axis in the left-right direction of the page, and a plurality of ring-shaped infrared lamps 5a arranged in a ring. A light source 5 formed as a cylindrical light source arranged coaxially in the axial direction and arranged concentrically around the reaction chamber 1 and surrounding the reaction chamber 1.
A, an output side capacitor 1 of the RF power supply 10 is arranged concentrically with the reaction chamber 1 between the light source 5A and the reaction chamber 1, and is connected to the RF power supply 10.
A thin film is formed on the surface of the substrate 8 placed in the reaction chamber 1 by the following procedure. .

First, the inside of the reaction chamber 1 is evacuated via the exhaust pipe 2 by a vacuum pump (not shown), and the raw material gas 3 is pumped into the reaction chamber 1.
The pressure is such that plasma is generated inside the chamber. Next, the light source 5A is turned on and the RF electrode 4A and this R
A substrate holder 6 that also serves as an RF electrode paired with the F electrode 4A
100kHz to several tens of MHz between
A high frequency voltage of the order of magnitude is applied. A single crystal film is likely to be produced in a thermochemical reaction using only a light source of 5A, and an RF power source of 10
Since a non-crystalline film is likely to be generated in the discharge decomposition reaction caused by a single discharge, the heating power supplied to the light source 5A and the plasma generation power supplied between the RF electrode 4^ and the substrate holder 6 should be set appropriately depending on the purpose. The source gas is decomposed to form a thin film on the surface of the substrate 8 placed on the substrate holder 6.

The apparatus shown in FIG. 5 has an axis extending above and below the plane of the paper.

A rod-shaped lamp 5b is used as a light source to provide thermal energy to the raw material gas in the reaction chamber 11 formed in a cylindrical shape with a low height.
A light source 5B formed as a flat light source with
is arranged on the film-forming surface side of the substrate 8 in parallel with the substrate, and a mesh-shaped plane electrode 4B is arranged between the light source 5B and the substrate 8.
RF'til! The substrate is heated from the back side of the substrate 8 by heating the substrate holder 6 from a substrate heating source 9 having a heat transfer surface with a diameter slightly larger than the diameter of the substrate 8. It is done through. Therefore, the substrate holder 6 and the substrate heating source 9 serve as the ground side RFilt pole.

[Problem to be solved by the invention]

In this way, in conventional devices, the RF electrode and the light source are arranged in an overlapping state when viewed from the substrate, so the light energy reaching the source gas from the light source is attenuated by the RF electrode, reducing reaction efficiency. There was a problem that the growth rate of the film decreased. In addition, the mesh-like RFii pole has a spread that almost covers the irradiation surface of the light source, and the plasma spreads throughout the reaction chamber, forming a thin film all over the inside of the reaction chamber, which takes time to clean. was there.

Furthermore, in the case where the light source and the RF electrode are housed inside the reaction chamber, there is a problem in that a thin film is also formed on the light source and the RF electrode, and these must be cleaned frequently.

An object of the present invention is to be able to apply light energy from a light source to a source gas without being attenuated by an RF electrode, and to prevent decomposition or activation of the source gas from occurring only in a localized area around the substrate. It is an object of the present invention to provide a structure of a vapor phase growth apparatus that reduces the amount of cleaning work.

[Means to solve the problem]

In order to solve the above problems, the present invention includes a transparent reaction chamber made of a dielectric material, a light source that irradiates the raw material gas introduced into the reaction chamber, and a power supply that converts the raw material gas into plasma. The light source is located in the reaction chamber, and the vapor phase growth apparatus is equipped with a pair of discharge electrodes, and forms a thin film on the surface of a substrate placed in the reaction chamber by decomposing or activating a source gas with light energy and electrical energy. The pair of discharge electrodes are each formed in a ring shape almost densely surrounding the reaction chamber, and are opposed in a direction parallel to the surface of the substrate at positions sandwiching the substrate and at intervals wider than the width of the substrate. The structure shall be arranged as follows. In the vapor phase growth apparatus having this structure, either an infrared light source that heats the raw material gas or an ultraviolet light source that excites the raw material gas can be arbitrarily selected and equipped as a light source depending on the components of the film to be formed. It is suitable to use it as a device. In addition, the light source is
More preferably, the light source is formed as a ring-shaped or cylindrical light source that surrounds the reaction chamber.

As for the specific structure of the apparatus equipped with this ring-shaped or cylindrical light source, the reaction chamber is formed as a cylindrical container in which the substrate is placed parallel to the axis, and the light source is
It is preferable that the cylindrical light source is formed by a plurality of ring-shaped lamps arranged coaxially in the axial direction of the ring, and the cylindrical light source surrounds the reaction chamber and is arranged concentrically with the reaction chamber.
Further, the reaction chamber has walls parallel to the substrate on both sides of the substrate. When formed as a container with a rectangular cross section, the light source is formed as a planar light source with a plurality of rod-shaped or ring-shaped lamps arranged in one plane, and the planar light source is placed on the side of the substrate on which the film is to be formed. It is preferable to have a device structure arranged parallel to the wall surface.

[Effect]

When a vapor phase growth apparatus using composite energy is formed into such a structure, the light energy from the light source reaches the raw material gas without being blocked by the discharge electrodes, so it can be used in a limited area in the reaction chamber between the discharge electrodes. The raw material gas inside is efficiently decomposed or activated by the light energy and electrical energy that have arrived, making it possible to prevent a decrease in the film formation rate. In addition, the contaminated area within the reaction chamber is localized, reducing the amount of cleaning work required when cleaning the reaction chamber, and since the light source and discharge electrode are also installed outside the reaction chamber, they are not contaminated by reaction products. Since there is no need for cleaning, the downtime of the device for cleaning can be shortened, and the operating efficiency of the device can be increased.

In addition, the vapor phase growth apparatus having this structure can be used as a light source depending on the components of the film, for example, when forming a Si film, an infrared light source may be used.
tozM! If the device is equipped with an ultraviolet light source during formation, or can be equipped with either an infrared light source or an ultraviolet light source, the device can be operated efficiently and the composite thin film forming technology can be made more efficient. can be promoted in a The ultraviolet lamp that constitutes the ultraviolet light source is usually a quartz tube filled with rare gas, and the ultraviolet light is emitted by arc discharge within the quartz tube, so the length of the quartz tube should be adjusted according to the power supply voltage of the light source. However, the infrared lamp that constitutes the infrared light source usually has a heat-generating filament sealed in a quartz tube, and this filament is set according to the power supply voltage of the light source and the desired heat output (number of wands) of the lamp itself. By appropriately designing the length of the quartz tube, it is possible to freely set the length of the quartz tube within a wide range, and by matching the length of the tube of the ultraviolet lamp and the tube of the lamp alone, it is possible to freely select either light source. membrane can be done.

If these light sources are formed as a ring-shaped or cylindrical light source that surrounds the reaction chamber, the reaction chamber is wrapped inside the light source and the raw material gas is efficiently heated or excited.

Therefore, the reaction chamber is formed as a cylindrical container, and the light source is formed as a cylindrical light source consisting of a plurality of ring-shaped lamps arranged coaxially in the axial direction of the ring. By arranging them concentrically, the raw material gas in the reaction chamber receives light energy uniformly in the radial direction and circumferential direction of the reaction chamber, and the raw material gas is efficiently and uniformly heated or excited. In addition, in this case, since the reaction chamber is formed as a cylinder whose diameter does not change in the axial direction, a pair of ring-shaped electrodes surrounding the reaction chamber almost densely also naturally
They are formed to have the same shape and the same dimensions, and an electric field distribution close to that of a parallel plate electrode can be obtained between the two electrodes, and electric energy can be supplied to the raw material gas in a uniformly distributed manner. Further, it becomes possible to easily adjust and set the optimum electrode spacing to obtain the desired film quality and film formation characteristics.

Further, the reaction chamber has walls parallel to the substrate on both sides of the substrate. It is formed as a container with a square cross section, and the light source is e.g.
By arranging multiple rod-shaped lamps in parallel in one plane, or by arranging ring-shaped lamps with different diameters concentrically in one plane to create a flat light source, a lamp with a simple shape can be used to create a light source with a square cross section. For example, it is possible to uniformly heat or excite the raw material gas within a reaction chamber shaped like a rectangular cylinder or a flat cylinder.

〔Example〕

In FIG. 1, which shows a first embodiment of the present invention, the same members as in FIGS. 4 and 5 are given the same reference numerals. In this embodiment, the light source 5A is an infrared light source for the purpose of forming a Si film, for example, and is formed as a cylindrical light source with a plurality of ring-shaped infrared lamps 5a arranged coaxially in the axial direction of the ring. concentrically surrounds. RFtl [10 to high frequency to give electrical energy to the raw material gas.

For example, the RF electrode 2 to which a voltage of 13.56 MHz is applied
4a.

24b is formed as a ring-shaped plate electrode having an inner diameter approximately equal to the outer diameter of the reaction chamber 1, and is fitted into the reaction chamber 1;
The substrate 8 is held at a position sandwiching the substrate 8 at an interval wider than the substrate width. This holding is carried out via the connecting rods 12a and 12b by a support member 16 formed by bending a metal plate into a mouth shape and having holes with the same diameter as the outer diameter of the reaction chamber 1 in both side walls 16a and 16b. be exposed. Note that the tip of the connecting rod 12a is connected to RFi.
The side wall 1 is screwed into the screw hole formed in the i-pole 24a and covered with a small diameter insulator tube wrapped in the metal tube 14.
6B supports the RFt source side end.

When the vapor phase growth apparatus is formed in this way, the thermal energy from the light source 5A reaches the source gas without being hindered by the RF [poles 24a and 24b, efficiently heating the source gas, and is supplied from the RFt source 10. Plasma 15 is formed in a limited area around the substrate 8, and the raw material gas in this cheek area is efficiently decomposed by the combined energy of thermal energy and electric energy to form a thin film on the substrate surface. Since the power supplied to the light source 5A can be set so that decomposition of the raw material gas does not occur outside this area, the wall surface of the reaction chamber is not contaminated, and therefore a lot of time is required for cleaning the reaction chamber. I don't.

FIG. 2 shows a second embodiment of the invention, which includes:
For example, for the purpose of forming a 5iO1 film, the light source 5A in the first embodiment is replaced with an ultraviolet light source 5D, and a configuration example of a low-temperature vapor phase growth apparatus in which the source gas is decomposed using the combined energy of ultraviolet excitation energy and electric energy. The configuration of the device is the same as in the first embodiment except that the substrate 8 is heated by a substrate heating source 9 and the RF electrode 24a is connected to the RFlii source 1o via a coaxial cable 17. .

The reason why the connection between the RF electrode 24a and the RFl source 10 can be made into components using a coaxial cable is that the light source 5D is an ultraviolet light source and the connection portion is not exposed to heating irradiation.

FIG. 3 shows a third embodiment of the present invention. In this embodiment, a reaction chamber 21 has wall surfaces parallel to the substrate 8 on both sides of the substrate 8. The reaction chamber 21 of the light source 5E is formed as a rectangular cylinder with a rectangular cross section, for example, a rectangular cylinder that is long in the axial direction, or a flat cylindrical container with the above-mentioned wall surfaces serving as both axial end faces. In some cases, a plurality of rod-shaped infrared lamps 5e are arranged as a flat light source in one plane, and in a case where the reaction chamber 2 is formed in a flat cylindrical shape, a light source (not shown here) may be used. It is formed as a flat light source in which ring-shaped infrared lamps with different diameters are arranged concentrically within one plane. This plane light source 5E is arranged above the side wall surface 21a of the film-forming surface of the substrate 8 in parallel with the wall surface 21a, and
Evenly irradiates the raw material gas inside. Moreover, the electrodes 25a, 2
Each of electrodes 5b is configured as a rectangular ring-shaped plate electrode that almost tightly surrounds the reaction chamber 21.

〔Effect of the invention〕

In the present invention, since the vapor phase growth apparatus is configured as described above, the following effects can be achieved.

In the apparatus of claim 1, the light energy from the light source reaches the source gas without being hindered by the discharge electrodes, so that the source gas within a localized area in the reaction chamber sandwiched between the discharge electrodes absorbs the reached light energy. It is efficiently decomposed or activated by the and electric energy, and a decrease in the film formation rate can be prevented. In addition, the contaminated area 8i inside the reaction chamber is localized, reducing the amount of cleaning work required when cleaning the reaction chamber, and since the light source and discharge electrode are also installed outside the reaction chamber, they are prevented from being contaminated by reaction products. Since there is no need for cleaning, the downtime of the device for cleaning can be shortened and the operational efficiency of the device can be increased.

According to claims 2 and 3, in the vapor phase growth apparatus which can be equipped with an infrared light source or an ultraviolet light source, the apparatus can be efficiently operated by forming the apparatus main body or the light source so that both light sources can be replaced with each other. It is possible to efficiently promote composite thin film formation technology that uses combined energy of light energy and electrical energy to decompose or activate raw material gas.

In the apparatus of the fourth aspect, since the reaction chamber is surrounded by the ring-shaped or cylindrical light source, the raw material gas is efficiently heated or excited. Therefore, less electric power is required to obtain the required combined energy.

In the apparatus of the fifth aspect, the raw material gas in the reaction chamber receives light energy uniformly in the radial direction and circumferential direction of the reaction chamber, so that the raw material gas is efficiently and uniformly heated or excited. In addition, the raw material gas in the region of the reaction chamber, which is sandwiched between ring-shaped electrodes that almost densely surround the reaction chamber and face each other in the axial direction of the reaction chamber,
Since an electric field distribution similar to that of parallel plate electrodes is obtained between the two electrodes, electric energy is supplied in a uniform distribution.

This makes it possible to form a WNWA with a more uniform film thickness distribution. Further, it becomes possible to easily adjust and set the optimum electrode spacing in order to obtain the desired film quality and film formation characteristics.

In the apparatus of the present invention, it is possible to uniformly heat or excite the raw material gas within a reaction chamber having a rectangular cross section, for example, a rectangular tube shape or a flat cylindrical shape, using a lamp having a simple shape.

[Brief explanation of the drawing]

FIGS. 1, 2 and 3 respectively show a first structure of a vapor phase growth apparatus according to the present invention. Partial cross-sectional side views showing the second and third embodiments, and FIGS. 4 and 5 are side cross-sectional views showing structural examples of conventional vapor phase growth apparatuses, respectively. 1.11.21: Reaction chamber, 3: Raw material gas, 4A, 4B
, 24a24b, 25a, 25b: RF ii pole
(discharge electrode), 5A, 5B, 5E: light source (infrared light source), 5a, 5b, 5e: lamp, 5D: light source (ultraviolet light source), 5d: lamp, 8: substrate, 10: RFt source (source), 15; plasma. Daij! Personal patent attorney Iwao Yamaguchi

Claims (1)

[Claims] 1) A transparent reaction chamber made of a dielectric, a light source that irradiates a source gas introduced into the reaction chamber, and a pair of discharge electrodes connected to a power source that turns the source gas into plasma. In a vapor phase growth apparatus that decomposes or activates a source gas with light energy and electrical energy to form a thin film on the surface of a substrate placed in a reaction chamber, the light source is arranged outside the reaction chamber. In addition, the pair of discharge electrodes are each formed in a ring shape that almost densely surrounds the reaction chamber, and are arranged opposite to each other in a direction parallel to the surface of the substrate at positions sandwiching the substrate and at intervals wider than the width of the substrate. A vapor phase growth apparatus characterized by: 2) The vapor phase growth apparatus according to claim 1, wherein the light source is an infrared light source that heats the raw material gas. 3) The vapor phase growth apparatus according to claim 1, wherein the light source is an ultraviolet light source that excites the raw material gas. 4) The vapor phase growth apparatus according to claim 1, 2 or 3, wherein the light source is formed as a ring-shaped or cylindrical light source surrounding the reaction chamber. Phase growth device. 5) In the vapor phase growth apparatus according to claim 4, the reaction chamber is formed as a cylindrical container in which the substrate is placed parallel to the axis, and the light source is provided with a plurality of ring-shaped lamps arranged in the direction of the axis of the ring. 1. A vapor phase growth apparatus characterized in that the cylindrical light source is formed as a cylindrical light source arranged coaxially with a reaction chamber, and the cylindrical light source surrounds a reaction chamber and is arranged concentrically with the reaction chamber. 6) In the vapor phase growth apparatus according to claim 1, 2, or 3, the reaction chamber is formed as a container having a rectangular cross section and having wall surfaces parallel to the substrate on both sides of the substrate. , the light source is formed as a planar light source formed by arranging a plurality of rod-shaped or ring-shaped lamps in one plane, and the planar light source is arranged parallel to the container wall surface on the film-forming surface side of the substrate. Vapor phase growth equipment.