JPH1092758A - Wafer loading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of film formation in a wafer face in a method for loading a wafer on a vertical wafer holder. SOLUTION: In the vertical wafer holder used in the heat treatment device of a vertical CVD device and the like, a wafer to be treated 4 is mounted on a wafer supporting groove R provided for four wafer supporting rods 3a-3d as shown in a broken line and a wafer position adjusting mechanism 7 moves the wafer 4 in the direction of an arrow as shown in a solid line. Then, the area of an overlap area (area to which hatching is added) with the groove R of the wafer 4 is reduced in a range where a wafer supporting state is maintained. Then, the wafer holder is set in the treatment chamber of the vertical CVD device in a state where the wafer is supported, for example. In the treatment chamber, a CVD treatment is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for loading a wafer into a vertical wafer holder used in a heat treatment apparatus such as a vertical CVD (chemical vapor deposition) apparatus, and more particularly to a method for mounting a wafer to be processed on the wafer holder. By adjusting the post-wafer position, the uniformity of film formation on the wafer surface is improved.

[0002]

2. Description of the Related Art Conventionally, as a vertical wafer holder used in a vertical heat treatment apparatus, one shown in FIGS. 7 and 8 is known (for example, see Japanese Utility Model Publication No. 7-15138).

The vertical wafer holder shown in FIGS.
It is made of quartz or silicon or a combination thereof. Four wafer support rods 3a to 3d are arranged upright between the lower plate 1 and the upper plate 2, and a large number of wafer support rods are provided inside each wafer support rod. The wafer support grooves R are engraved, and the wafers 4 to be processed such as semiconductor wafers are supported by four wafer support grooves having the same installation level.

When loading a wafer into a wafer holder,
For example, as shown in FIG. 8, a wafer 4 set on a wafer carrier 5 is taken out by a wafer transfer system 6 having a wafer support 6a and transferred to a wafer holder along a path indicated by arrows A, B, C and D. Then, the wafer 4 is placed in the wafer support grooves of the wafer support rods 3a to 3d. Such an operation is automatically performed by the wafer loader.

[0005] Thereafter, the wafer holder is set in a processing chamber of, for example, a vertical CVD apparatus while supporting the wafer. In the processing chamber, a film forming process by CVD is performed.

[0006]

According to the above-mentioned prior art, the wafer 4 is often set in a state of being in contact with the side surface inside the wafer support groove R as shown in FIG. When the film forming process is performed in such a contact state, an overlapping area with the groove R of the wafer 4 (an area hatched in FIG. 1)
In this case, since the growth of the film is suppressed, the thickness of the film becomes thinner than other portions, and there is a problem that the uniformity of film formation on the wafer surface is deteriorated.

An object of the present invention is to provide a novel wafer loading method capable of improving the uniformity of film formation on a wafer surface.

[0008]

According to the present invention, there is provided a wafer loading method including a step of placing a wafer to be processed in a wafer support groove provided in a plurality of wafer support rods constituting a vertical wafer holder. The position of the wafer to be processed is adjusted so that the area of the overlapping area of the wafer to be processed and the wafer supporting groove is reduced within a range where the wafer supporting state is maintained.

According to the method of the present invention, the area of the overlapping region of the wafer with the wafer supporting groove is reduced, so that when the film forming process is performed, the region having a small film thickness is reduced and the in-plane surface of the wafer is reduced. Film thickness variation is reduced.

[0010]

1 and 2 show a wafer mounting step and a wafer position adjusting step in a wafer loading method according to the present invention, respectively. The steps in FIG. 1 are also shown in FIGS. 3A and 4A, and the steps in FIG. 2 are also shown in FIGS. 3B and 4B. 1 to 4, the same parts as those in FIGS. 7 and 8 are denoted by the same reference numerals, and detailed description thereof will be omitted.

First, in the wafer mounting step, the wafer supporting grooves R provided in the four wafer supporting rods 3a to 3d constituting the vertical wafer holder in the same manner as described above with reference to FIG.
A wafer 4 to be processed, such as a semiconductor wafer, is placed in such a direction that the orientation flat 4F is away from the support rods 3b, 3c (FIGS. 1, 3A and 4A). At this time, the wafer 4 has the groove R as shown in FIGS.
It is often set in a state in which it touches the side inside. The area of this result, the center P ₂ of the wafer 4, the support rods 3b from the center P ₁ of the wafer holder, will be due to 3c side, overlapping area between the groove R of the wafer 4 (the hatched region in FIG. 1) Will also be quite large.

Next, in the wafer position adjusting step, the wafer 4 is moved in the direction of the arrow by the mechanism 7 while the arms 7a and 7b of the wafer position adjusting mechanism 7 are in contact with the edge of the wafer 4 (FIGS. 2 and 3). 3 (B), FIG. 4 (B)). At this time, the movement amount of the wafer 4 is, for example, the center P of the wafer 4.
₂ is the degree to substantially match the center P ₁ of the wafer holder. As a result, the wafer 4 is separated from the side surface inside the groove R as shown in FIGS. 1 and 4B, and overlaps with the groove R of the wafer 4 (the hatched area in FIG. 2). Is smaller than that in FIG.

The amount of movement of the wafer 4 in the step shown in FIG. 2 is not limited to the above example, and the center P _{2 of the} wafer 4 should exceed the center P ₁ of the wafer holder as long as the wafer supporting state is maintained. You may. By doing so, the area of the overlapping region with the groove R of the wafer 4 can be further reduced.

The vertical wafer holder loaded with the wafer as described above is set in a processing chamber of a vertical CVD apparatus as an example. In the processing chamber, a film forming process by CVD is performed.

FIG. 5 shows a case where the wafer 4 comes into contact with the side surface in the groove R of the support rod 3b (a case indicated by a solid line 4;
3 (A), 4 (A) and the prior art),
In the case where the wafer 4 does not contact the side surface in the groove R of the support rod 3b (this is the case indicated by the broken line 4; FIGS. 2, 3B and 4).
(B) and (corresponding to the present invention) show the state of formation of the CVD film 8 on the wafer 4.

In forming the CVD film 8, a silicon wafer was used as the wafer 4. Then, TEOS is placed on the wafer 4.
LP (Low P) made from (Tetra Ethyl Ortho Silicate)
A silicon oxide film was formed as a CVD film 8 by the CVD method. The CVD conditions at this time are as follows:
10 [° C], degree of vacuum 30 [Pa], TEOS flow rate 60
[Cc / min], and the target film thickness was 280 [nm].

After the CVD process, the wafer 4 was taken out from the wafer holder and the thickness of the CVD film 8 was measured. FIG. 6 (A)
5A and 5B show the distribution of the measurement points a to g of the CVD film thickness in the two cases of FIG. 5, and FIG. 5A corresponds to the case where the wafer 4 is shown by a solid line in FIG. B) corresponds to the case where the broken line indicates the wafer 4 in FIG. In FIGS. 5 and 6, the distance from the tip R ₀ of the groove R to the tip in a groove R of the wafer 4 shown by a solid line in FIG. 5 and L _1, the tip of the groove R R ₀
Assuming that the distance from the tip of the wafer 4 within the groove R indicated by the broken line in FIG. 5 to L ₂ is L ₂ , L ₁ = 10.0 [mm] and L ₂ =
It was 5.0 [mm]. In FIG. 6, X-
X 'line is a center line passing through the centering P ₂ of the wafer 4 and the center of the support rod 3b, between a-b, the spacing between the measuring points, such as between b-c is met approximately 2 [mm] Was.

The following Table 1 shows measurement points a to a shown in FIG.
5 shows the result of measuring the thickness of the CVD film 8 for g.

[0019]

[Table 1] Table 2 below shows the results of measuring the thickness of the CVD film 8 at the measurement points a to g shown in FIG.

[0020]

[Table 2] The variation in the film thickness in the vicinity of the edge of the wafer 4 shown in FIG. 6 is obtained by the following equation (1).

[0021]

(Equation 1) When the film thickness variation in the case of Table 1 is obtained in accordance with the equation (1), it is 9.3 [%]. In addition, according to the equation (1), Table 2
When the film thickness variation in the case of (1) is obtained, it is 5.2 [%]. Therefore, it can be seen that the film thickness variation is smaller in the case of Table 2 according to the present invention. Further, comparing the film thicknesses at the measurement point a in Tables 1 and 2, it can be seen that the film thickness in Table 2 according to the present invention is larger.

[0022]

As described above, according to the present invention, after the wafer to be processed is placed on the vertical wafer holder, the position of the wafer is adjusted so as to reduce the area of the overlapping region with the wafer supporting groove of the wafer. It is possible to improve the uniformity of film formation in the wafer surface, and to obtain the effect of improving the yield in the film formation process.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a vertical wafer holder showing a wafer mounting step in a wafer loading method according to the present invention.

FIG. 2 is a cross-sectional view of a vertical wafer holder showing a wafer position adjusting step following the step of FIG. 1;

FIG. 3 is a side view of a vertical wafer holder corresponding to the steps of FIGS. 1 and 2;

FIG. 4 is a cross-sectional view of a wafer support corresponding to the steps of FIGS. 1 and 2;

FIG. 5 is a cross-sectional view of a wafer support portion showing a state of forming a CVD film when a wafer contacts a side surface of a wafer support groove;

6 is a plan view of a wafer showing a distribution of measurement points of a CVD film thickness in the two cases shown in FIG. 5;

FIG. 7 is a perspective view showing a conventional vertical wafer holder.

8 is a perspective view showing a method for loading a wafer into the wafer holder of FIG. 7;

[Explanation of symbols]

1: lower plate, 2: upper plate, 3a to 3d: wafer support rod, 4:
Wafer to be processed, 5: Wafer carrier, 6: Wafer transport system, 7: Wafer position adjusting mechanism, 8: CVD film, R: Wafer support groove.

Claims (1)

[Claims] 1. A wafer loading method comprising a step of placing a wafer to be processed in a wafer support groove provided in a plurality of wafer support rods constituting a vertical wafer holder. A wafer loading method comprising: adjusting a position of the wafer to be processed so as to reduce an area of an overlapping region with the wafer support groove within a range where a wafer support state is maintained.