JPH0732139B2 - Vertical wafer boat - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wafer boat, and more particularly to a vertical wafer boat used in a vapor phase growth apparatus in which a reaction vessel is set upright.

[Conventional technology]

Conventionally, this type of vertical wafer boat is shown in FIG.
As shown in (b), a plurality of vertically standing columns (3 or more) are provided with grooves at substantially equal intervals. As shown in FIGS. 2 (a) and 2 (b), the film formation is performed by mounting the wafer 4 in the groove of each column 5 of the wafer boat so that the wafer boat is rotated and is substantially parallel to the wafer growth surface. It was carried out by flowing a reaction gas into.

[Problems to be Solved by the Invention]

Conventionally, in the vapor phase growth method in which a vertical wafer boat is used to flow a reaction gas almost parallel to the wafer growth surface, the support of the wafer boat hinders the supply of the reaction gas onto the wafer growth surface. There was a drawback that the film thickness uniformity and resistivity uniformity in the vicinity were poor. FIG. 4 shows the state of the reaction gas flow in the vicinity of the conventional vertical wafer boat. It should be noted that there is a region where the reaction gas supply amount is very small in the vicinity of the boat column 5 in the wafer growth plane. I understand. The reaction gas flow in the vicinity of the support column 5 is changed from a laminar flow to a turbulent state under the influence of the support column 5, and eddy flow is particularly generated in the vicinity of the support column 5. It is getting wider. For this reason, the film thickness uniformity and the resistivity uniformity in the vicinity of the support column 5 are deteriorated. The size of the adverse effect of this boat support depends on the diameter of the support 5, the positional relationship between the support 5 and the wafer growth surface, the number of support 5 and the like. That is, as the number of columns is smaller, the diameter is smaller, and the columns are farther from the wafer growth surface, the influence on the film thickness uniformity and the resistivity uniformity of the boat columns is smaller. However, in the conventional wafer boat, since the wafer 4 is mounted so as to be sandwiched between the grooves provided in the support column 5, the wafer growth surface and the support column cannot be separated. Moreover, the wafer cannot be held unless there are three or more columns. Further, there is a problem that the diameter of the support column cannot be reduced due to the problem of the strength of the boat.

[Means for Solving the Problems]

The vertical wafer boat of the present invention holds and rotates a plurality of vapor phase growth substrates (wafers) so as to be horizontally stacked, and for each of the plurality of wafers, the growth surface of each wafer is almost It is used in a vapor phase growth apparatus that deposits films by extending the nozzle tube so that the reaction gas flows in parallel, and the wafer mounting part is composed of a disk or ring susceptor with a diameter larger than the wafer diameter. Cage,
In addition, it is characterized in that the number of columns supporting the susceptor is two or one.

Therefore, if the diameter of the disk-shaped or ring-shaped wafer susceptor is increased, the distance between the boat support and the wafer growth surface can be increased. Further, since the susceptor is fixed to the boat support, the wafer can be mounted even with two or one support. Further, because of the structure, the susceptor itself also serves as a boat reinforcing material, so that there is an advantage that the diameter of the boat support can be reduced. Therefore, by using the wafer boat of the present invention, it is possible to form a wafer having a uniform film thickness and resistivity on the wafer surface.

Note that quartz, poly-Si, or SiC is preferably used as the material of the vertical wafer boat.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a) and 1 (b) show a vertical wafer boat according to an embodiment of the present invention. This boat is composed of two 10 mmφ columns 3 and a ring on which a wafer is mounted. This boat is used in various film deposition systems with a reaction tube set upright, but here we will describe the Si epitaxial growth system.

FIG. 3 is a vertical Si using the wafer boat of the present invention.
It is a longitudinal cross-sectional view of an epitaxial growth apparatus. This apparatus is provided with a pedestal 8 for supporting the apparatus, a reaction tube having a double tube structure composed of an outer tube 6 and an inner tube 7, a wafer boat 9 of the present invention for mounting a Si wafer, a resistance heating furnace 11 and a reaction gas. It is composed of a nozzle tube 12 that operates.

One P-type Si wafer 10 with a diameter of 150 mm is placed in the wafer boat 9.
Fifty wafers were mounted at 0 mm intervals, the wafer boat 9 was rotated at a rotation speed of 5 rpm (5 rpm), and the temperature inside the reaction tube was set to 1050 ° C. ₂₀ L / min of H ₂ and 400 ml / mi of SiN ₂ Cl ₂ from the nozzle tube 12.
N and PN ₃ were flown at 50 ml / min, and an N-type Si epitaxial film was grown on the Si wafer 10 at a pressure of 10 torr for 30 minutes. Sixth
The figure shows the film thickness distribution and resistivity distribution on the wafer surface at this time, but the result when using the conventional wafer boat (4 16 mmφ struts) described for reference It can be seen that the film thickness distribution and the resistivity distribution are improved as compared with. In particular, the resistivity distribution was remarkably improved, and in the case of the conventional boat, the region where the constant resistivity line near the support was dense was about 30% of the entire surface of the wafer, whereas the boat of the present invention was used. In this case, the phenomenon occurred up to about 5%. As a result, good uniformity of a film thickness distribution of ± 3% and a resistivity distribution of ± 5% within the wafer surface excluding the 5 mm outer periphery of the wafer was obtained.

Next, a 10,000-gate bipolar gate array was prototyped using the wafer boat of the present invention. When a conventional boat was used, 30% of the area within the wafer surface where the resistivity was poor was the present invention. In case of the boat, the rate of non-defective products improved by about 30%, corresponding to the decrease of 5%.

FIG. 1 (c) shows a vertical wafer boat according to another embodiment of the present invention. In this embodiment, the boat support column 3
From 2 to 1, and the diameter of the column 3 from 10mmφ to 14mm
Expanded to φ. This is intended to reduce the area of the wafer affected by the pillars from two to one by reducing the number of pillars. However, due to strength issues, the strut diameter is 40% thicker. The Si epitaxial growth apparatus and the growth conditions were the same as in the case of one example for film formation. FIG. 7 shows the film thickness distribution and the resistivity distribution at that time. In the case of the present example, the equi-resistivity lines in the vicinity of the support were reduced from two dense areas to one area. However, since the pillar is thicker, the influence per pillar is slightly wider than that in the first embodiment. Therefore, in the case of the present embodiment as well, almost the same good film thickness uniformity and resistivity uniformity were obtained as in the case of one embodiment.

〔The invention's effect〕

As described above, according to the present invention, since the wafer mounting portion of the vertical wafer boat is configured by the disc or the ring-shaped susceptor having a diameter larger than the wafer diameter, the number of boat support columns is reduced to two or one. Since the pillar diameter can be reduced and the pillar and the wafer growth surface can be separated,
The region affected by the turbulence of the reaction gas flow generated by the boat support in the wafer growth plane can be significantly reduced, and the film thickness and the resistivity distribution can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a) and 1 (b) show a wafer boat according to an embodiment of the present invention, and FIG. 1 (c) shows a wafer boat according to another embodiment of the present invention. 2A and 2B are views showing a conventional wafer boat and a wafer mounting method,
FIG. 3 is a diagram showing a vertical type vapor phase growth apparatus used in an embodiment of the present invention, FIG. 4 is a diagram showing a state of a reaction gas flow in the vicinity of a boat column, and FIG. 5 is a conventional wafer boat. FIG. 6 is a diagram showing a resistivity distribution in the case of using a wafer, FIG. 6 is a diagram showing a resistivity distribution in the case of using the wafer boat of one embodiment of the present invention, and FIG. 7 is another embodiment of the present invention. FIG. 6 is a diagram showing a resistivity distribution when the wafer boat of FIG. 1 ... Wafer, 2 ... Susceptor, 3 ... Boat support,
4 ... Wafer, 5 ... Boat support, 6 ... Outer tube, 7 ...
… Inner tube, 8 …… Stand, 9 …… Wafer boat, 10 …… Wafer, 11 …… Resistance heating furnace, 12 …… Nozzle tube, 13 …… Gas exhaust hole, 14 …… Exhaust port.

Claims (1)

[Claims] 1. A plurality of vapor phase growth substrates (wafers) are held and rotated so as to be stacked horizontally, and the reaction gas is applied to each of the plurality of wafers substantially parallel to the growth surface of each wafer. In a vertical wafer boat used in a vapor phase growth apparatus in which a nozzle tube is extended to form a film, the wafer mounting part is a disk or ring susceptor with a diameter larger than the wafer diameter. A vertical wafer boat, which is configured and has two or one support columns for supporting the susceptor.