JPH0626182B2 - Infrared heating device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an infrared heating device in a hydrogen atmosphere, and more particularly to an infrared heating device for Si (silicon) wafers used in the semiconductor industry.

2. Description of the Related Art A conventional heating device has adopted a method of heating in an electric furnace. When this method is performed in the atmosphere, with the lid open, the container is heated to the target temperature and the semiconductor wafer is taken in and out, and rapid heating and rapid cooling are also possible.
However, there is a problem that the wafer is oxidized by exposing it to the atmosphere, and therefore heating and cooling must be performed in a gas atmosphere in order to avoid contact of the wafer with air. However, since a normal electric furnace has a large heat capacity, there is a problem that rapid heating and rapid cooling cannot be performed in a gas atmosphere. Therefore, in recent years, an infrared heating device, which enables rapid heating and cooling by reducing the heat capacity of the device itself, has attracted attention.

An example of the conventional infrared heating device described above will be described below with reference to the drawings.

FIG. 4 shows a conventional infrared heating device.

Reference numeral 1 denotes a quartz bell jar as an infrared ray transmitting container, and the quartz bell jar 1 and the base plate 2 can completely block the outside air. Base plate 2
A gas supply port 3 for supplying gas and a gas discharge port 4 for discharging gas are attached to the. A base 6 on which the semiconductor substrate 5 is placed is installed on the base plate 2. The base 6 is made of transparent quartz in order to avoid contamination of impurities or decomposition by heating. An infrared lamp 7 for heating the semiconductor substrate 5 and a reflecting mirror 8 for efficiently irradiating the semiconductor substrate 5 in the quartz bell jar 1 with the light rays of the infrared lamp 7 are attached to the outer side of the upper part of the quartz bell jar 1. ing.

The operation of the infrared heating device configured as described above will be described below.

The hydrogen gas supplied from the gas supply port 3 is supplied to the gas discharge port 4
The semiconductor substrate 5 discharged from the substrate 6 and placed on the base 6 is
In the hydrogen atmosphere, the light from the infrared lamp 7
It is heated to 1000 ℃.

Further, a case where the same apparatus is applied to vapor phase growth of a polycrystalline silicon film will be described. The constituent elements are exactly the same, and the semiconductor substrate 5 placed on the base 6 is heated to a temperature of about 700 to 800 ° C. by being irradiated with light from the infrared lamp 7. On the other hand, a gas supply device (not shown) supplies a mixed gas of monosilane as a reaction gas and hydrogen as a carrier gas. This mixed gas is
The reaction gas molecules flowing toward the gas outlet 4 and contacting the base 6 and the semiconductor substrate 5 at this time to remove heat and reach a predetermined temperature or higher are decomposed and deposited to deposit a polycrystalline silicon film on the semiconductor substrate. (Eg "Latest LSI process technology",
Industrial Research Council, P211 to 229, P385 to P393).

Problems to be Solved by the Invention However, in the above-mentioned configuration, since the base 6 is made of transparent quartz, most of the light of the infrared lamp 7 is transmitted therethrough, so the temperature does not rise so much. Therefore, the semiconductor substrate 5 always receives the heating beam from the upper surface, but the heat is absorbed more and more from below. Further, when focusing on the base 6, heat is absorbed from the upper part, but the absorbed heat also releases heat to the lower side and the side. Therefore, the flow of heat flows downward and laterally, and the influence also affects the inside of the semiconductor substrate 5 placed on the upper surface, and the heat is radiated downward and laterally of the semiconductor substrate 5. As a result, the temperature on the semiconductor substrate 5 is lower at the edges than at the center, resulting in poor temperature uniformity and crystal defects due to thermal stress. Further, when this apparatus is applied to vapor phase growth with the same configuration, there is a problem that the film thickness of the deposited film also becomes uneven due to the uneven temperature.

Means for Solving the Problems In order to solve the above problems, the infrared heating device of the present invention comprises a container having a gas supply port and a gas discharge port, at least a part of which is light transmissive, and an external container. An infrared lamp for radiatively heating the inside of the container, and a base for mounting a semiconductor substrate inside the container, the semiconductor substrate being made of a material having a greater light absorption coefficient in the vicinity of the outer periphery than other portions. It is a thing.

Operation According to the present invention, the semiconductor substrate that receives the heating rays from the infrared lamp has the above-described configuration, and the heat is absorbed downward, but the vicinity of the outer periphery is made of a material having a higher light absorption rate than the conventional example. Therefore, the lateral flow of heat from the semiconductor substrate is reduced as a result of heat transfer or heat radiation from the vicinity of the outer periphery, and the temperature uniformity on the semiconductor substrate is improved.

Example An infrared heating apparatus according to an example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of an infrared heating apparatus according to the first embodiment of the present invention.

In FIG. 1, 9 is a heating chamber, and a water cooling groove 10 is provided inside.
Is provided with a wall member 11 made of heat resistant and corrosion resistant metal such as stainless steel and an upper opening / closing block 12. An infrared lamp heater unit 13 as an infrared source is installed inside the upper opening / closing block 12, and a transparent quartz plate 14 is provided at a position close to the infrared lamp heater unit 13 as a gas sealing means such as an O-ring. It is fixed by a fixing tool 15 via. The upper opening / closing block 12 can be moved up and down, and by lifting it upward, the upper portion of the heating chamber is opened, and the semiconductor substrate 16 can be loaded and unloaded. Further, by lowering the upper opening / closing block 12 and fixing it at a position in contact with the wall surface member 11 through the O-ring, an airtight chamber completely shielded from the outside air is formed. A gas exhaust port 18 is connected to one end of the heating chamber 9 to which a gas supply pipe 17 extending from a gas supply device (not shown) is connected, and an exhaust pipe 19 is connected to the other end of the gas exhaust gas. A mouth 20 is provided. Inside the heating chamber 9, a base 21 for mounting the semiconductor substrate 16 at a position facing the infrared lamp heater unit 13 via the quartz plate 14 is installed. As shown in FIG. 2, the base 21 is made of transparent quartz 22 on the inside and graphite 23 on the outside. It is configured to fit from above as shown.

Regarding the infrared heating device configured as described above,
The operation will be described with reference to FIGS.

The hydrogen gas supplied from the gas supply port 18 is exhausted from the gas exhaust port 20. The semiconductor substrate 16 and the base 21 which received the light beam from the infrared lamp heater unit 13 in a hydrogen atmosphere are heated to 1000 ° C.

The base 21 is composed of transparent quartz 22 and graphite 23, and the graphite 23 absorbs more light rays from the infrared lamp heater unit 13 than the transparent quartz 22. As a result, heat is supplied to the transparent quartz 22 from the infrared lamp heater unit 13 and the semiconductor substrate 16 from above, and further heat is also supplied from the lateral graphite 23. Therefore, the heat flow inside the transparent quartz 22 decreases from the center to the side, and most of the heat flows downward. As a result, the distribution of the heat flow emitted from the semiconductor substrate 16 to the base 21 becomes uniform,
The temperature difference between the end and the center of the semiconductor substrate 16 is reduced, and the temperature distribution can be made uniform.

A case where this apparatus is applied to vapor phase growth of a polycrystalline silicon film will be described. The semiconductor substrate 16 and the base 21 are heated to about 700 to 800 ° C. On the other hand, in a gas supply device (not shown), a mixed gas of monosilane as a reaction gas and hydrogen as a carrier gas is supplied from the gas supply port 18 and exhausted from the gas exhaust port 20. When the mixed gas absorbs heat on the base 21 and the semiconductor substrate 16 and reaches a predetermined temperature or higher, the reactive gas molecules are decomposed and a polycrystalline silicon film is deposited on the semiconductor substrate. in this case,
Since the temperature distribution of the semiconductor substrate is uniform, the film thickness of the deposited film is also uniform.

As described above, according to the present embodiment, as the base for mounting the semiconductor substrate, by using a material having a larger infrared light absorptance in the vicinity of the outer periphery than the other parts, The temperature distribution can be made uniform.

Another embodiment of the present invention will be described below with reference to the drawings.

3 (a) to 3 (h) are bases of infrared devices showing other embodiments of the present invention, and the infrared heating devices are all second
The configuration is the same as shown.

The base shown in FIG. 3 (a) has a shape in which graphite 23a is fitted into transparent quartz 22a as in FIG. 2, but the difference from FIG. 2 is that the periphery of the semiconductor substrate 16 is graphite 23a. Is the point of contact with.

The base shown in FIG. 3 (b) differs from the base shown in FIG. 3 (a) in that a space is provided below the semiconductor substrate 16.

The base shown in FIG. 3 (c) has a configuration in which both the transparent quartz 22c and the graphite 23c are directly placed in the heating chamber 19.

In the base shown in FIG. 3 (d), the base shown in FIG. 3 (c) and the transparent quartz 22d and the graphite 23d have the same shape,
The difference is that a space is provided below the semiconductor substrate 16.

In the base of FIG. 3 (e), the semiconductor substrate 16 is graphite 2
It is separated from 3e for a certain period of time and is placed on the transparent quartz 22e.

The base of FIG. 3 (f) has a shape in which transparent quartz 22f is fitted into concave graphite 23f.

The base shown in FIG. 3 (g) has a shape in which graphite 23g is fitted in grooves provided at a constant distance from the outer surface of transparent quartz 22g.

The base of FIG. 3 (h) is the base of FIG. 3 (g) and the transparent quartz 22h,
Same as graphite 23h, but semiconductor substrate 16
Is different in that the periphery of is in contact with graphite 23h.

The heat flow of each of the bases configured as described above is exactly the same in principle as that of the base shown in FIG. 2, and the heat flow to the side of the semiconductor substrate 16 is As a result, the temperature distribution can be made uniform.

In each of the above-described embodiments, the base 21 is made of transparent quartz having an outer circumference of graphite, but other materials may be used as long as the outer circumference absorbs more infrared light than the inner circumference. Is also good.

Although the transparent quartz plate 14 is made of transparent quartz, other materials may be used as long as they have infrared light transmissivity.

In the present embodiment, the outer periphery of the base is made of graphite, but graphite may be coated with silicon carbide in consideration of contamination of impurities.

EFFECTS OF THE INVENTION As described above, according to the present invention, the base for mounting the semiconductor substrate inside the container to be radiatively heated is made of a material having a higher light absorption rate in the vicinity of the outer periphery than in other portions. This makes it possible to obtain a temperature distribution with good uniformity on the semiconductor substrate,
As a result, crystal defects of the semiconductor substrate due to thermal stress can be prevented, and the uniformity of the film thickness of the deposited film in vapor phase growth can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an infrared heating device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of a base, and FIGS. 3 (a) to (h) are sectional views of a base in another embodiment. FIG. 4 and FIG. 4 are sectional views of a conventional infrared heating device. 9 ... Heating chamber, 13 ... Infrared lamp heater unit, 14 ... Transparent quartz plate, 16 ... Semiconductor substrate,
18 ... Gas supply port, 20 ... Gas exhaust port, 21 ... Base, 22 ... Transparent quartz, 23 ... Graphite.

Continuation of the front page (56) References JP-A-58-42225 (JP, A) JP-A-61-219130 (JP, A) JP-A-60-263428 (JP, A)

Claims (3)

[Claims] 1. A container, at least partially transparent to light, having a gas supply port and a gas discharge port, and a container external to the container,
An infrared source for radiatively heating the inside of the container, and a base for mounting a semiconductor substrate inside the container,
An infrared heating device in which the central portion of the base is made of quartz glass, and the outer peripheral portion or the vicinity of the outer peripheral portion of the semiconductor substrate is made of a material having a higher light absorption rate than the quartz glass. 2. The infrared heating device according to claim 1, wherein the periphery of the base is made of graphite. 3. The infrared heating device according to claim 1, wherein the periphery of the base is made of graphite coated with silicon carbide and the other portion is made of transparent quartz.