JP3077447B2 - Vapor phase growth method and reaction vessel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vapor phase growth (hereinafter referred to as CVD).
And a reaction vessel used for CVD.

In the process of manufacturing a semiconductor device, various thin films such as a polysilicon film, a nitride film and an oxide film are formed on a wafer surface by a CVD method. Reduced pressure CV for flowing a reaction gas while reducing the pressure inside a reaction tube or reaction vessel in a CVD apparatus
The D apparatus is often used because the number of processed wafers is large and it is easy to cope with an increase in the diameter of the wafer. However, the increase in the diameter of the wafer necessitates a decrease in throughput or an increase in the size of the apparatus. And a solution is desired.

[0003]

2. Description of the Related Art Conventionally, when a large number of wafers are batch-processed by a low pressure CVD apparatus, the wafers are aligned in the same direction in the front and back direction and at the same interval in a reaction vessel. At this time, the wafer interval is set to a good uniformity of the film thickness within the wafer (hereinafter, referred to as a “wafer thickness”).
In order to obtain the uniformity of the film thickness, an appropriate value is set according to various conditions such as the distance between the wafer and the inner wall of the reaction vessel, the pressure value in the reaction vessel, and the diameter of the wafer.

[0004]

However, if the wafer spacing is reduced to increase the number of processed wafers in one batch in order to increase the throughput of the apparatus, the uniformity of the film thickness tends to be impaired (especially when the SiO ₂ film is grown. Therefore, there is a problem that it is difficult to increase the throughput of the apparatus by reducing the wafer interval.

The present invention solves such a problem and, when batch processing a large number of wafers by a low pressure CVD apparatus, is capable of improving the throughput of the apparatus without impairing the yield of processed wafers. And a reaction container.

[0006]

According to the present invention, there is provided [1] holding a plurality of wafers in parallel at predetermined intervals.
The accommodated tubular reaction vessel is disposed in a reaction tube,
In the vapor phase growth method of forming a thin film on the surface of the wafer by flowing a reaction gas in the vessel , a plurality of the wafer,
The front surface and the back surface alternately face each other, and
The spacing between the surfaces is smaller than the spacing between the opposing surfaces.
And over the entire circumference with the inner wall of the reaction vessel.
Arranged so that the distances are approximately equal, and
[2] Holding and storing a plurality of wafers at predetermined intervals in parallel by using a vapor phase growth method characterized by flowing a reactive gas.
And reactant gas is circulated in the reaction tube so that the surface of the wafer
In a cylindrical reaction vessel that forms a thin film on the
The cross-sectional shape is similar to the wafer, the distance between the inner wall and the wafer is substantially equal over the entire circumference of the wafer, and the distance between the opposing wafers is alternately smaller than the first interval and the first interval. This is achieved by providing a reaction container characterized in that the wafer is held and accommodated at two intervals.

[0007]

The formation of a thin film is usually required only on the front side of the wafer. On the back side, a thin film is formed because a space is provided even during processing for wafer handling (especially automatic handling), but it is originally unnecessary,
The film thickness uniformity may be reduced to some extent (however,
Extremely non-uniformity may hinder the lithography process, etc.).

In the present invention, the surface sides requiring good film thickness uniformity and the back surfaces not requiring excessive film thickness uniformity are opposed to each other to obtain good film thickness uniformity between the surfaces. By making the distance between the back surfaces smaller than the distance between the front surfaces within a range that does not hinder wafer handling, the throughput of the apparatus can be improved without impairing the film thickness uniformity on the front surface side.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a CVD method and a reactor for a CVD apparatus according to the present invention will be described with reference to FIGS. In this example, an SiO ₂ film is formed on a Si wafer by a vacuum furnace of a tubular furnace type.

First, the reaction vessel will be described. FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a perspective view showing an embodiment of the present invention. In the figure, 1 is a wafer, 10 is a reaction vessel, 11 is a boat, 12 is a cover, W is the distance between the inner wall of the reaction vessel 10 and the wafer 1, H1 is the first distance between wafers, H2
Is also the second interval. The material of the boat 11 and the cover 12 is quartz glass or SiC.

When the cover 12 is overlaid on the boat 11, the cross-sectional shape of the internal space becomes a cylindrical reaction vessel 10 having a substantially similar shape to the wafer 1. Its inner diameter is 2 × larger than the diameter of wafer 1.
It is large only by W (details described later).

The boat 11 and the cover 12 each have a slit 11
a and 12a, which serve as gas flow ports of the reaction vessel 10. Therefore, the reaction vessel 10 is a semi-closed vessel. Boat 11
A leg for stabilizing the attitude of the reaction vessel 10 is provided on the outside of the bottom (not shown).

The boat 11 has spacers 11b and 11c inside the bottom.
The upper edge has a flange 11d. The spacer 11b and the flange 11d are provided with grooves at a predetermined pitch (details will be described later) into which the peripheral portion of the wafer 1 is loosely fitted. The spacers 11b, 11c, and the flange 11d allow the wafer 1 to be moved around the entire circumference thereof. It stands upright in parallel with the inner wall of 10 so as to be equidistant (W).

The pitch of the grooves provided in the spacer 11b and the flange 11d is such that the intervals between the wafers 1 to be erected are alternately the first interval H1 and the second interval H2. Of these, H1 is set according to various conditions such as the distance W between the wafer 1 and the inner wall of the reaction vessel 10 and the pressure value in the reaction vessel 10 in order to obtain good film thickness uniformity. It is empirically appropriate that H1 is about twice as large as W at a commonly used pressure value in the reaction vessel. On the other hand, H2 is smaller than H1, and when the wafer 1 is inserted into and removed from the reaction vessel 10, the wafer 1
Larger than the thickness of the robot chuck that absorbs

Next, the CVD method will be described. First, a predetermined number of wafers 1 are set upright in the boat 11 of the reaction vessel 10 by a robot. At this time, the wafer 1 is inverted every other sheet so that the front surface and the back surface of the wafer 1 alternately face each other, and the wafer interval between the front surfaces is H1 and the wafer interval between the back surfaces is H2. Next, select the groove position. Thereafter, the cover 12 is placed on the boat 11, placed in a reaction tube made of quartz or the like, heated by a hot wall method, and supplied with a reaction gas while reducing the pressure.

The wafer 1 is placed in the above-mentioned semi-closed reaction vessel.
When storing in an open boat instead of storing in 10 and processing it in a reaction tube, the above-mentioned W must be increased, H1 also increases, and the throughput decreases.

The inventor of the present invention accommodated 75 wafers by the above-described method in the above-described reaction vessel 10 having the same outer dimensions as a conventional reaction vessel accommodating 50 wafers, and formed an SiO ₂ film thereon. The throughput (however, the number of processed sheets per core in a multi-stage furnace) can be increased to 28 without loss of film thickness uniformity.
% Could be improved. In this comparative example, each of the wafer diameters was 6 inches, the distance W was 5 mm, the conventional groove pitch (wafer interval + wafer thickness) was 9.52 mm, and the groove pitch of the present invention was 9.52 mm (equivalent to H1) and 4.76. mm (equivalent to H2).

The reason why the increase in throughput is lower than the increase in the number of accommodated wafers (50%) is that the transfer of the wafer by the robot has increased 1.5 times with the increase in the number of wafers and that the gross rate with the increase in the number of wafers has increased. Due to extending the growth time to compensate for the drop.

The present invention is not limited to the above embodiments, but can be implemented in various modifications. For example, instead of setting the above-mentioned two types of groove pitches, large and small, all are unified into small pitches, and by selectively using grooves, even when changing the wafer spacing, or when using a vertical furnace However, the present invention is effective.

[0020]

As described above, according to the present invention,
When a large number of wafers are batch-processed by a low-pressure CVD apparatus, it is possible to provide a vapor phase growth method and a reaction vessel capable of improving the throughput of the apparatus without deteriorating the yield of processed wafers. It contributes to cost reduction.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Wafer 10 Reaction vessel 11 Boat 11a, 12a Slit (gas flow port) 11b, 11c Spacer 11d Flange H1 First spacing (spacing between surfaces) H2 Second spacing (spacing between backs) W Reaction vessel inner wall and wafer Distance to

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01L 21/205 H01L 21/365 H01L 21/31 H01L 21/22 511 C23C 16/00

Claims (2)

(57) [Claims] 1. A method for holding a plurality of wafers in parallel at predetermined intervals.
The cylindrical reaction vessel held and stored is placed in the reaction tube,
In a vapor phase growth method for forming a thin film on the surface of a wafer by flowing a reaction gas through a reaction vessel , a plurality of the wafers are alternately paired between a front surface and a back surface.
The distance between the opposing back surfaces is between the opposing front surfaces.
So that it is smaller than the interval, and over each circumference
Arranged so that the distance from the inner wall of the reaction vessel is substantially equal
And flowing a reaction gas through the reaction vessel . 2. A plurality of wafers are held and stored in parallel at a predetermined interval, and a reaction gas is circulated in a reaction tube to form the wafers.
In a cylindrical reaction vessel that forms a thin film on the surface of c, the sectional shape of the storage space is similar to that of the wafer, and the inner wall is
The distance between the wafer and the wafer is approximately equal over the entire circumference of the wafer.
And the opposing wafers alternate between the first
And a second interval smaller than the first interval.
A reaction container for holding and storing a wafer .