JPS59171113A - Heat-treatment furnace for semiconductor wafer - Google Patents

Abstract

PURPOSE:To keep the temperature in a reaction tube uniform by a method wherein, when semiconductor wafers are contained in the reaction tube and the wafers are heated by a high frequency oscillation coil provided outside the tube, a layer of heat insulation material or a double transparent quartz tube with vacuum heat insulation are provided between the reaction tube and the coil. CONSTITUTION:The circumference of a reaction tube 4, composed of a high purity transparent quartz tube, is surrounded by a layer 2 of heat insulation material such as alumina-wool and a high-frequency oscillation coil 7 is applied outside the layer 2. A ladder shape holding device 6 on which semiconductor wafers 5 are arranged is inserted into the reaction tube 4 and the wafers 5 only are heated by current application to the coil 7 and are subjected to heat treatment such as diffusion or oxidization. Instead of the layer 2 of heat insulation material, a double transparent quartz tube with vacuum heat insulation, composed of an inner wall 4a and an outer wall 4b which are made of the same material as the reaction tube 4, may be used to reduce the thickness of the heat insulation compared to that of the layer 2. With this constitution, the heat generation of the reaction tube 4 is reduced and its life can be extended and the temperature in the tube 4 can be uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a semiconductor device '! The reaction tube of the heat treatment furnace used for the upper stages of diffusion and oxidation of the A-making process, especially the direct frequency wave
g4 Heating relates to the structure of reaction γ1 in a heat treatment furnace in which semiconductor wafers are heated for 1 hour by infrared heating.

In recent years, the diameter of silicon single crystals has been increasing year by year due to the e-i technology of Noricon single crystal dragon technology.
mφ or 125mmφ is the mainstream, and further 150mm
The diameter is increasing to φ. , this tendency is Th1O
It is predicted that this trend will continue in the future due to the decreasing cost of #8IC and other similar devices.

Generally, when manufacturing semiconductor devices such as MO8ICs, high-temperature heat treatment at 800-1250'C is usually repeated several times for oxidation, diffusion, etc. Figure 1 shows the cross-sectional structure of a commonly used heat treatment furnace, in which a heating wire 1 is spirally wound around the outer periphery and a heat insulating material 2 is placed on the outside.
A reaction tube 4 made of a high-purity quartz tube is disposed along its entire length on the inner surface of a soaking tube 3 made of alumina/recon carbide, and semiconductors, such as/recon wafers 5, are arranged in this reaction tube 4 (r Insert the ladder-like support base 6,
Heat treatment such as diffusion and oxidation is performed by heating at a predetermined temperature and time.

(~ As mentioned in 1-1, as the diameter of the silicon polycrystal increases, the reaction tube suddenly becomes larger. Furnace load 71j
Disadvantages arise such as an increase in , consumption 'rtr, and power.

In particular, as the diameter of the transparent quartz tube used as the reaction tube 7 increases, the price increases, and the lifespan of the tube during high-temperature heat treatment becomes shorter. For example, if a commercially available transparent quartz tube for a 100 m diameter + xφ Noricon wafer used for a diffusion T culm is used with a diameter of about 700 + Samurai 1i4j at x250'c, the tube wall of the reaction tube will devitrify and become bent, requiring replacement. . [
] For silicon wafers and wafers with a diameter of 125 + + + + πφ, the life is shortened to about 500 hours 1. In order to extend the life of the reaction tube, are there effective methods such as thickening the wall of the reaction tube or coating the outside of the reaction tube with alumina? This has the disadvantage of being expensive.

On the other hand, the method of directly heating semiconductor wafers with high-frequency induction coils or infrared lamps is commonly used in Evita kinetic growth equipment, etc. It is conceivable to adopt these heating methods to lower the temperature and extend the life of the semiconductor, but when oxidizing or diffusing a large number of semiconductor wafers by arranging them on a ladder-like support in a reaction tube, conventional If a high-frequency induction coil or an infrared lamp is installed around the outer circumference of the reaction tube to heat the semiconductor wafer, the amount of heat radiated from the reaction tube will be large, and the scale will not be able to save energy or the wafer will be bent. Temperature variations between wafers are likely to occur,
It is not possible to obtain uniform semiconductor wafers.

The present invention has been made in view of the above points, and provides a semiconductor wafer that has excellent heat retention effects and good thermal uniformity even when high-frequency induction heating or infrared heating is used for diffusion and oxidation of semiconductor wafers. It provides the means to obtain the desired results.

Next, the present invention will be explained based on examples.

FIG. 2 shows an embodiment of the present invention, and the same reference numerals as in FIG. 1 are designated by the same names. In Fig. 2, for example, the reaction tube 4 (glue) side, which is made of a high-purity quartz tube, is insulated with ``alumina cool'', 4J2, etc.
After placing such a reaction tube 4 inside the high-frequency oscillation coil 7, insert the ladder stand 6 on which the semiconductor chips 5 are lined up into the reaction tube 4 and turn on the electricity, so that only the semiconductor chips are heated and oxidized. -C: A heat treatment is performed.

Figures 3 and 3 show another embodiment of the present invention, and the difference between Figure 3 and Figure 2 is that no insulation is used at all. In Figure 3, the outside of a reaction tube 4 made of a high-purity transparent quartz tube is covered with a reaction tube 4a made of the same material, and both ends 8 of this reaction tube 4a connect the inner reaction tube 4 and the outer reaction tube 4a. An exhaust port 9 fixed in a bathing suit and provided at one end.
For example, the space formed by these two reaction tubes is evacuated and maintained at a high vacuum of less than I x 10 torr through a vacuum chamber. ,′-? , shut off exhaust air 9. In this way, the di-salt space formed by the reaction tubes 4 and 4a fulfills the role of vacuum insulation, and is especially 1/2 that of the case where the insulation material 2 made of alumina wool or the like shown in Fig. 2 is used. ~
Even with a thickness of 2/3, it has a sufficient heat retention effect, and since the reaction tube wall is transparent, it has the advantage that it can be applied not only to high-frequency induction heating methods but also to infrared heating methods.

4 and 5 show a modification of the embodiment shown in FIGS. 2 and 3, and in this case as well, the same reference numerals as in FIGS. 2 and 3 respectively are represented by the same names. Figure 4 shows the case using heat insulating material, and Figure 5 shows the case without using heat insulating material.
This is a case where the reaction tube has a double structure. 4 and 5, a semiconductor pipe 10 made of the same material as the semiconductor wafer, for example polycrystalline silicon, is inserted into the reaction tube 4. As shown in FIGS.

The semiconductor ueno sheets 5 are arranged on a ladder-like support 6 and inserted into a pipe 10 made of a copper conductor, and then subjected to heat treatment. As a result, in the case of the high frequency induction heating method, the semiconductor wafer 5
In addition to the semiconductor pipe 1 placed outside the
0 can be heated at the same time, so if the infrared heating method is still used, the semiconductor wafer 5 will be heated by radiation as the semiconductor pipe IO is heated, so the temperature within and between the surfaces of the semiconductor wafers 1 and 5 will increase. The uniformity of the fractions ji is superior to the embodiments shown in FIGS. 2 and 3.

As explained above, in the present invention, the area around the reaction tube is kept warm.
The temperature inside the reaction tube is more uniform than the equation. Additionally, according to the present invention, only the semiconductor wafer or only the semi-duplicated wafer and the semiconductor vibrator generate heat7, and the reaction tube generates little heat, so the life of a reaction tube made of, for example, a transparent quartz tube is greatly extended. .

For example, a lifting platform used for heat treatment of 12,500 or more, 125
ynmφ, for reconwafer, reaches 5000 hours. In addition, a heating element such as a resistance heating type heat treatment furnace can be used to keep the temperature of the heat-retaining phase and reaction tube low. -f: As a result, the amount of evaporation of the heavy metal impurities contained in these is small, and therefore there is little intrusion into the semiconductor sea urchin, and high quality semiconductor sea urchin can be obtained. In other words, since diffusion and oxidation occur in a clean atmosphere, ■
Even with ultra-high resistivity silicon used in radiation detectors, there are significant advantages such as no change in resistivity or decrease in lifetime, and no intrusion of positive charges into the oxide film. These advantages greatly contribute to improving the characteristics of various semiconductor devices such as power buoys, diodes, and MO8rC that require a high-quality oxide film, which require a long lifetime.Of course, the upper Since the semiconductor wafer is directly heated as in Ii, it has a great effect of reducing power consumption, but it is also of great significance in order to conserve resources as raw crystals in Brazil are becoming depleted. expensive.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a conventional resistance heating type heat treatment furnace, FIGS. 2 and 3 are sectional views showing the sectional structure of a direct heating type heat treatment furnace according to the present invention, and FIGS. FIG. 3 is a sectional view of a heat treatment furnace showing a modification of the embodiment of FIGS. 2 and 3, respectively. 1″ 5. Heat wire, 2. Heat insulation, 3 Soaking tube, 1,4a
Reaction tube, 5, semiconductor ueno, 6 Ladder-shaped support, 7
High frequency oscillation coil, 8 Bath fitting section, 9 ・Exhaust port, 10
Semiconductor-made) Kubu. 51 Figure 1 7 Figure 4

Claims (1)

[Claims] 1) Four biopsied sea urchins in a reaction tube are heated by electromagnetic waves irradiated from outside the tube. In addition, the heat radiation from inside the pipe is 1
The means to fti n is gayera! ) A heat treatment furnace for 1' conductor. 2) Special g! 1: j! 1) In the furnace described in Section 1, the semiconductor woofer is characterized in that the means for inhibiting heat radiation is a blank, heat-insulating awning and a transparent quartz tube. Heat treatment furnace. 3) Cow'i R'r The furnace for heat treatment of semiconductor sawdust according to claim 2, wherein the electromagnetic wave is a high frequency wave, and the means for preventing heat radiation is a heat insulating material. 4) In the furnace according to any one of claims 1 to 3, surrounding the semiconductor wafer in the reaction tube,
A heat treatment furnace for semiconductor sea urchins characterized by having seven tubes made of the same semiconductor as the wafers.