JPS61187326A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE:To make the temperature on wafer surface even by a method wherein the winding pitch of heat element in infrared ray lamps for heating wafer and wafer holder is changed. CONSTITUTION:Each infrared lamp 13 is supplied with regulated power to heat a wafer 10 mounted on a wafer holder 11 up to specified temperature while He base reaction gas is fed 8 and exhausted 9 making the pressure in the reaction chamber 3 10Torr or less to form a poly Si film on the wafer 10. At this time, three each of infrared ray lamps at the central part change the winding pitch of heat element 2 to reduce the radiant heat quantity toward the central part of wafer holder 11 limiting the dispersion of temperature distribution on wafer surface to 10 deg.C or less.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vapor phase growth apparatus widely used in the semiconductor industry.

Conventional technology In the vapor phase growth equipment used in the semiconductor industry, reactive gas molecules are thermally decomposed on the surface of a semiconductor wafer to form a thin film such as polycrystalline silicon, but the thickness of the thin film formed in this way is , and the uniformity of resistivity are greatly influenced by the surface temperature of the semiconductor wafer. Therefore, in order to obtain a high quality vapor phase grown film, it is necessary to maintain a uniform temperature distribution over the entire surface of the semiconductor wafer.

A conventional vapor phase growth apparatus using an infrared heating method has a structure as shown in FIG. 3, as shown in Japanese Patent Publication No. 57-44009, for example. The reaction chamber can be completely isolated from the outside air by a quartz belljar 15 and a base plate 16, and the base plate 16 has a gas supply port 17 for supplying the reaction gas and a gas supply port 17 for discharging the reaction gas. A gas outlet 22 is attached. Furthermore, a wafer support stand 19 on which a semiconductor wafer 18 is placed is installed on the pace plate 16 . Further, on the outside of the quartz belljar 15, an infrared lamp 21 for heating the semiconductor wafer 18 and a reflecting mirror 2o are attached so that the reflected light from the infrared lamp 210 efficiently irradiates the semiconductor wafer 18.

Problems to be Solved by the Invention However, in the conventional vapor phase growth apparatus configured as described above, the temperature distribution on the surface of the semiconductor wafer 18 is dependent on the thermal energy supplied from the infrared lamp 21 and the semiconductor wafer 18 and sea urchin. ...Determined by the amount of heat released by convection, radiation, etc. from the support table 19, the upper surface of the wafer support table receives a certain amount of radiant heat from the infrared lamp, while the outer peripheral surface is not shielded from heat, A large amount of heat corresponding to the surface temperature is released. Therefore, Ueno/support stand 19
The temperature distribution on the surface of the semiconductor substrate 18 is high at the center and low at the outer periphery. Also, in the infrared lamp itself, the temperature of the heating element tends to be higher in the center than at the ends. As a result, semiconductor wafer 18
The thin film grown in a vapor phase on top had the disadvantage that it was thinner at the edges than at the center. In order to avoid these situations, methods have been taken to control the power applied to each infrared lamp, but this does not solve the problem of uneven temperature distribution in the portions located parallel to each infrared lamp. Furthermore, a method in which the wafer support table is rotated completely is considered, but the mechanism is complicated and may cause dust generation, which leaves problems.

Therefore, the present invention has developed a vapor phase growth apparatus that eliminates the unevenness of temperature distribution in the part located parallel to the infrared lamp, makes the temperature uniform on the semiconductor wafer, and forms a high quality vapor phase growth film with excellent uniformity. It provides:

Means for solving the problems and technical means of the present invention for solving the above problems are as follows:
The winding pitch of the heating element of an infrared lamp for heating a semiconductor wafer and a wafer support is varied.

action The effect of this technical means is as follows.

In other words, if the temperature at the center of a semiconductor wafer to be heated is higher than that at the edges, by making the winding pitch at the center of the heating element of the infrared lamp located above the wafer wider than at the edges, By reducing the amount of radiant heat to the wafer surface, it is possible to equalize the temperature of the wafer surface.

EXAMPLE Hereinafter, as an example of the present invention, an infrared heating type vapor phase growth apparatus will be described with reference to the drawings.

FIG. 2 is a sectional view of the vapor phase growth apparatus of the present invention. In the figure, the reaction chamber 3 is composed of a wall member 5 made of stainless steel and having a water cooling groove 4 therein, and a transparent quartz plate 6 provided on the upper part.

This transparent quartz plate 6 is fixed to the wall member 5 via a known gas sealing means such as an O-ring.

At one end of the side wall of the reaction chamber 3, there is a gas supply port 8 connected to a gas supply pipe 7 extending from a gas supply device (not shown), and at the other end there is an exhaust port 9 connected to a vacuum evacuation device such as a rotary pump (not shown). It is a provision. Further, inside the reaction chamber 3, a wafer support 11 made of graphite coated with SiC is installed on which the wafer 10 is placed, and a transparent quartz plate θ is installed above the outside of the reaction chamber 3. A heating block 12 is attached at a position facing the wafer support stand 11 across the wafer. This heating block 12 has a plurality (7) of horizontal rod-shaped infrared lamps 13 arranged at equal intervals so as to be perpendicular to the flow direction of the reaction gas flowing from the gas supply port 8 to the gas discharge port 9. It has a structure in which a reflecting mirror 14 is placed at the top. The infrared lamp 13 is divided into three zones: two on the gas supply side, three in the center, and two on the gas discharge side, each with a socket (not shown). It is electrically connected to the power conditioning unit through the infrared lamp, allowing temperature control in the direction perpendicular to each infrared lamp (gas flow direction).

Furthermore, as shown in Fig. 1, the central three infrared lamps have a winding pitch of 100 fl in the center of the heating element (tungsten filament) 2 inside the transparent quartz glass 1, which is 1.3 times wider than that at both ends. I used the one I made.

The operation of the vapor phase growth apparatus having the above configuration will be explained using the growth of polycrystalline silicon as an example. First, the wafer 10 is placed on the upper surface of the wafer support 11, and each infrared lamp 13 is connected to a power adjustment unit (not shown). Electric power is supplied through the wafer to heat the wafer to a predetermined temperature of eoo''C or higher.At this time, a helium-based mixed gas containing a reactive gas such as monosilane at an appropriate concentration is supplied through the entire gas supply port 8. At the same time, the gas in the reaction chamber 3 is sucked through the exhaust port 9 using a rotary pump (not shown), etc.
When the pressure is maintained at a reduced pressure below rr, a reactive gas is separated out from the gas phase in contact with the wafer 10, and a polycrystalline silicon film is formed on the surface of the wafer 1o. In this vapor phase growth process, by using three infrared lamps located in the center zone with heating elements with different winding pitches, the amount of heat radiated to the center of the wafer support is reduced and the wafer surface is It was possible to suppress the occurrence of uneven temperature distribution in the wafer, and in turn, it was possible to improve the variation in film thickness within the wafer. In fact, in a conventional vapor phase growth apparatus equipped with an infrared lamp with a uniform heating element winding pitch, the temperature at the edge of the wafer is 20 degrees lower than that at the center of the wafer.
℃ or more, and the film thickness uniformity of the formed polycrystalline silicon was 110% or more.

On the other hand, in the vapor phase growth apparatus using an infrared lamp in which the winding pitch of the heating element of the present invention is changed, the temperature distribution unevenness of the wafer can be reduced to within i10'C, and as a result, the film thickness of the formed polycrystalline silicon can be reduced. The uniformity could be improved to within 6%.

In this example, the winding pitch of the heating element of the infrared lamp was used such that the center part 10o1al was 1.3 times wider than the end part, but the ratio can be adjusted arbitrarily depending on the shape of the wafer support, etc. Needless to say, you can choose.

In addition, although three infrared lamps in the central part of the heating block were used with different winding pitches of the heating elements, it goes without saying that the number of infrared lamps that can be attached is not limited to the above example.

Furthermore, although this embodiment is applied to a polycrystalline silicon vapor phase growth apparatus, it can also be applied to other vapor phase growth or annealing apparatuses.

Effects of the Invention As described above, the present invention makes it possible to obtain a uniform temperature distribution on the surface of a semiconductor wafer by changing the winding pitch of the heating element of an infrared lamp, thereby making it possible to grow a uniform film on the semiconductor wafer. The practical effects are great.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an infrared lamp used in an embodiment of the present invention, Fig. 2 is a sectional view of a vapor phase growth apparatus in an embodiment of the invention, and Fig. 3 is an example of a conventional vapor phase growth apparatus. FIG. 2... Heating element, 3... Reaction chamber, 10.
... Semiconductor wafer, 11 ... Wafer support stand, 13 ... Infrared lamp. Name of agent: Patent attorney Toshio Nakao and one other person
”I!l z---x body number
2 Figure 10-m-Semiconductor die △/1--Wafer support N mill

Claims (1)

[Claims] A wafer support stand on which a semiconductor wafer is placed, an infrared lamp having a winding-shaped heating element for heating the semiconductor wafer and the wafer support stand, and the wafer support stand are installed, and a gas supply port and a gas exhaust port are installed inside the wafer support stand. 1. A vapor phase growth apparatus comprising a reaction chamber having an opening, and having a winding pitch of a heating element of the infrared lamp varied.