JPS589579B2 - Hand Thai Souchino Seizou Souchino - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for manufacturing a semiconductor device manufactured by heat treating a semiconductor wafer.

Semiconductor devices are mainly manufactured using single-crystal silicon wafers, and the manufacturing process for these silicon semiconductor devices includes processes that require highly precise control, such as heat treatment and optical etching. Particularly in heat treatment steps, the crystallinity of silicon wafers is often impaired during diffusion of impurities or surface oxidation, and various causes of this problem have been pointed out.

The causes of loss of crystallinity of silicon wafers are as follows.

In other words, (1) the process of manufacturing the silicon wafer itself, that is, when making the single-crystal silicon ingot,
Or crystal defects that occur due to processing strain during subsequent slicing to obtain a wafer of a predetermined thickness.

:2) Strain that occurs during the process of temperature rise and fall in the heating furnace during heat treatment.

(3) Crystal defects caused by diffused impurity atoms depending on their type or concentration during diffusion.

etc.

Regarding these points, we can use dislocation-free single crystals (to deal with (1)), perform slow heating and cooling to prevent the occurrence of thermal stress (to deal with (2)), and reduce the diffusion concentration. Perfect crystal technology (PCT) is used ((3)
).

However, just as important as the above points is the effect that a so-called wafer boat, a device that supports silicon wafers during heat treatment, has on the crystallinity of the wafers.

Figure 1 shows an example of a wafer boat currently in use.
The boat body 1 has a frame made of silicon carbide or quartz, and guide grooves for vertically holding wafers are provided at regular intervals on two parallel sides of the frame.

FIG. 2 is a cross-sectional view of the wafer boat taken along line 1-1 in FIG. 1, in which silicon wafers 2 are supported by guide grooves and held upright.

In this case, the contact state between the guide groove and the wafer 2 is a surface contact, and if the silicon wafer 2 is heat-treated in this state, crystal defects are likely to occur in the silicon wafer 2 at this contact portion.

3a, b and 4 a, b are also commonly used wafer boats, and like the one in FIG. 1, the wafers 2 held are both structured so that they make surface contact in the guide groove of the boat. However, it is the same in that the crystal defects described above are likely to occur.

In other words, at the point where the wafer and the boat are in contact, there is a drawback that if the wafer is later divided into chips and tested as a semiconductor device, there is a high probability that the product will be defective.

This invention was made in view of the above points. An object of the present invention is to provide a semiconductor device manufacturing apparatus that can hold a semiconductor wafer vertically in point or line contact when the wafer is held in a thermal furnace or the like.

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

FIG. 5 is a side view of semiconductor wafer 12 held vertically.

The wafer 12 has four rod-shaped members 1 each having a circular cross section and which are horizontally arranged in contact with the peripheral edge of the wafer 12.
It is held by a supporting frame 11 consisting of 1, 112, 113, 114, and is supported by two lower rod-shaped members 11, , 11 placed at the bottom that support the weight of the wafer 12, and two lower rod members 11 placed on the sides. Position rod-shaped member 113,? 1 and are parallel to each other.

FIG. 6 is a plan view of the frame 11 and two wafers 12, 122.

The V-shaped guide grooves 13, , 13, 13, 132 formed in the side rod-shaped members 11, , 11, are arranged so that the wafers 12, 12 can be inserted into the respective guide grooves 13, 13, 13, 13.
The notch angle is 15° to make point contact with the inner wall surface of
Values between ˜60° have been chosen.

Also, the bottom member 11. 11 and wafer 12
．． 12 is not in surface contact but in line contact.

In addition, the material of each of the above-mentioned rod-shaped members is quartz.

With the configuration of the above embodiment, the semiconductor wafer 12 makes point contact within the guide groove 13, and line contact occurs at the bottom members 11 and 112 that support the weight of the wafer. ? That is, wafer 1
2. The weight of 12 is entirely due to the two lower rod-shaped members 11
．． 11 and is in line contact at right angles to the outer periphery of the round bar.

Therefore, the guide groove 1 of the side rod-shaped members 113, 114
3, 13. 13, 13 only need to prevent the wafers 12, 122 from tilting, so that no large stress is applied and the wafers 12, 12 can be stably held in point contact between them.

Therefore, if the wafer is supported by the frame 11 during heat treatment, effects such as loss of crystallinity can be almost prevented.

The following table shows the results of etching the semiconductor wafer surface and evaluating its defects after heat treatment using the apparatus having the above configuration and the conventional apparatus (FIG. 1).

The etching solution used was C r Os HF, the wafers in each device had the same design and the same pitch, and it goes without saying that the heating conditions were also constant.

That is, at a speed of 30 seconds, the crystallinity of silicon is impaired in both the device of the present invention and the conventional device, and it is difficult to expect an improvement in production yield, but with the device of the present invention, no defects occur at all at speeds of 2 minutes or more.

In addition, in the table above, the temperature increase/decrease rate refers to the time required to reach the specified temperature from the inlet of the furnace to the center of the furnace (up to 4 failures) when each of the above devices is inserted into the heating furnace. It shows.

In terms of heat treatment efficiency, the faster the speed change, the better, but the more rapid the temperature change in one throw, the more opportunities for crystal defects to occur.

As described above, according to the present invention, a plurality of semiconductor wafers are simultaneously held during heat treatment in the manufacturing process of semiconductor devices by supporting them with a point or line contact shape, thereby suppressing the occurrence of crystal defects in the wafers due to cram treatment, and It is possible to provide an apparatus for manufacturing semiconductor devices that contributes to an improvement in the yield of semiconductor devices and efficiently performs the heat treatment itself.

[Brief explanation of the drawing]

Figures 1 and 2 are views showing an example of a conventional boat for semiconductor wafers, Figures 3a and b are views showing another example of a conventional boat, and Figures 4a and b are still another example. A diagram showing
FIG. 5 is a side sectional view showing one embodiment of the device of the present invention, and FIG.
The figure is a plan view of the same embodiment. 11-114... Rod-shaped member with circular cross section, 12
1?22...
...Semiconductor wafer, 13,132...Guide groove.

Claims (1)

[Claims] 1. In a semiconductor device manufacturing apparatus that holds a plurality of three-dimensional semiconductor wafers in a furnace at the same time, two downwardly positioned rod-like members parallel to each other are located below the wafer periphery and support the weight of the wafer, and two downwardly positioned bar-like members are placed below the wafer periphery to support the wafer's own weight; two lateral rod-shaped rods each having a plurality of V-shaped guide grooves in the axial direction and each having a plurality of V-shaped guide grooves cut out at an angle of 15° to 600° on the inside, and holding the wafer in point contact with the guide groove walls; A semiconductor device manufacturing apparatus comprising: