JPH0737814A - Thin film forming device - Google Patents

Abstract

PURPOSE:To almost equalize the flow rate of a gaseous raw material running along the whole outer periphery of a semiconductor wafer by a method wherein a gap adjusting member is arranged in the gap between a notch part of the semiconductor wafer and a reaction tube inner wall so as to almost equalize the gap along the whole periphery. CONSTITUTION:When plural semiconductor wafers 3 are mounted on a holding member 20 for transfer to be contained in a reaction tube, the gap made in the nearby part to a notch part 3A of the semiconductor wafers 3 is almost equalized with the gap excluding the nearby part by a gap adjusting member 21 provided in the holding means 20 for transfer so as to almost equalize the whole peripheral gap of the semiconductor wafers 3. At this time, the gap adjusting member 21 is a bar type member 21 having an opposite surface 21a commonly opposing to the notch part 3A of the plural semiconductor wafers 3 mounted on the holding member 20 for transfer. Furthermore, the gap adjusting member 21 is arranged in the holding member for transfer so that the opposite surface 21A makes a specific gap at specific interval with the notch part 3A of a plurality of semiconductor wafers 3.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Industrial Application Conventional Technology (FIGS. 11 to 15) Problem to be Solved by the Invention (FIG. 16) Means for Solving the Problem (FIGS. 1 to 3) Action (FIGS. 1 to 3) Example (FIGS. 1-10) Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus, and is particularly suitable for application to a CVD (Chemical Vapor Deposition) apparatus for forming a uniform thin film by flowing a raw material gas on the surface of a silicon wafer.

[0003]

2. Description of the Related Art Conventionally, in this type of CVD apparatus,
There is a method in which a plurality of silicon wafers (hereinafter, referred to as wafers) are once mounted on a quartz boat, and the silicon wafer is loaded in the quartz boat and housed in a reaction furnace to flow a reaction gas. Figure 11
The low-pressure CVD apparatus 1 shown in (1) has a heater part 2 in the upper half part, and has an elevator mechanism (not shown) for transportation under the heater part 2. The CVD apparatus 1 uses the elevator mechanism to mount a plurality of wafers 3 on a quartz boat 4
Reactor 5 that conveys and is heated by being built in the heater unit 2.
It is designed to be housed inside.

As shown in FIG. 12, the reactor 5 has a cylindrical quartz outer tube 6 and a cylindrical quartz inner tube 7 inside the quartz outer tube 6, and a rotating mechanism at the bottom of the quartz outer tube 6. Part 8
With. Further, the inside of the reaction furnace 5 is kept in a vacuum state of 30 [Torr] or less. A quartz boat 4 having a plurality of wafers 3 mounted therein is mounted in a quartz inner tube 7 from the lower part of a reaction furnace 5 by an elevator through a mounting hole of a rotation mechanism section 8. When the quartz boat 4 is supported by the rotation mechanism portion 8, the heated reaction gas is caused to flow from the bottom to the top of the quartz inner tube 7. As a result, the reaction gas diffuses and each wafer 3
An ultra thin film is formed on the surface of.

As shown in FIGS. 13 and 14, the quartz boat 4 is provided with four columns 11 to 14 parallel to each other and reinforcing ribs 15 of the columns 11 to 14 between the upper and lower paired disks 9 and 10. ing. As shown in FIG. 15 in which the cross section of the quartz boat 4 is viewed upward, the width of each of the columns 11 to 14 is substantially equal to the thickness of the wafer 3, and the depth thereof is dug to about half of each of the columns 11 to 14. Slots 16 included
50 to 200 wafers are provided at the same intervals, so that 50 to 200 wafers 3 can be inserted into the slot 16, respectively.

[0006]

By the way, each wafer 3
Is once formed into a disc shape, and then a part of the outer periphery is cut with a straight line to cut out a crescent-shaped portion, whereby a notch (reference to the position of the integrated circuit formed on the wafer 3 ( Hereinafter, this will be referred to as an orientation flat) 3A. The wafers 3 are arranged on the quartz boat 4 with the orientation of the orientation flats 3A all aligned on the side into which the wafer 3 is inserted or on the opposite side.

However, as shown in FIG. 16, when the quartz boat 4 is housed in the quartz inner tube 7, the gap formed between the inner wall 7A of the quartz inner tube 7 and the outer periphery of the wafer 3 is inside the quartz. Since the tube 7 has a circular cross section, it is wide in the portion of the orientation flat 3A and uniform in the other portions. As a result, the orientation flat 3A
As the flow velocity of the reaction gas flowing through the gap of the portion becomes slow, the reaction gas stays in this portion, and the film forming rate near the orientation flat 3A becomes faster. As a result, there is a problem that it is difficult to obtain a uniform film thickness over the entire wafer 3.

Further, in order to make the thickness of the thin film uniform, the quartz boat 4 is rotated by the rotating mechanism portion 8 while the reaction gas is flowing. In this method, however, the rotating mechanism portion 8 is not rotated properly or is rotated from the rotating shaft. There is a problem that the outside air leaks into the reaction furnace 5 and the degree of vacuum is deteriorated, which is still insufficient as a solution.

The present invention has been made in consideration of the above points, and provides a thin film forming apparatus capable of making the flow velocity of a raw material gas flowing around the outer circumference of a plurality of semiconductor wafers housed in a reaction tube substantially uniform over the entire circumference. It is a proposal.

[0010]

In order to solve such a problem, in the present invention, a carrying holding member having a plurality of semiconductor wafers 3 each having a notch 3A is positioned at a predetermined position in a reaction tube. In the thin film forming apparatus for forming a thin film on the surface of the semiconductor wafer 3 by pouring a raw material gas on the surface of the semiconductor wafer 3 through a gap formed between the inner wall of the reaction tube and the semiconductor wafer 3,
A gap adjusting member is arranged in the gap formed between the notch portion 3A and the inner wall of the reaction tube so that the gap between the outer circumference of the semiconductor wafer 3 and the inner wall of the reaction tube is substantially uniform over the entire circumference. did.

Further, in the present invention, the gap adjusting member 21
Is a facing surface 21A that commonly faces the cutout portions 3A of the plurality of semiconductor wafers 3 mounted on the carrying holding member 20.
And is arranged on the carrier holding member 20 so that the facing surface 21A forms a predetermined gap between the facing surface 21A and the notches 3A of the plurality of semiconductor wafers 3. .

Further, in the present invention, the gap adjusting member 4
2 contacts the cutout portions 3A of the plurality of semiconductor wafers 3 mounted on the carrying holding member 40 with almost no space, and the plurality of semiconductor wafers 3 are cutout portions 3A.
It is arranged on the carrying holding member 40 so as to come close to the original shape with no gap.

Further, in the present invention, the gap adjusting member 3
OA is a facing surface 30 that is commonly facing the cutout portions 3A of the plurality of semiconductor wafers 3 mounted on the transport holding member 4.
A, and the opposing surface 30A is arranged on the inner wall of the reaction tube 30 so as to form a gap at a predetermined interval between the facing surface 30A and the cutout portions 3A of the plurality of semiconductor wafers 3.

Further, in the present invention, the carrier holding member 4 having a plurality of semiconductor wafers 3 each having a notch portion 3A mounted therein is positioned at a predetermined position in the reaction tube 7 and the inner wall of the reaction tube 7 and the semiconductor In a thin film forming apparatus for forming a thin film on the surface of the semiconductor wafer 3 by pouring a source gas onto the surface of the semiconductor wafer 3 through a gap formed between the semiconductor wafer 3 and the wafer 3, the cutout portions 3A of the semiconductor wafer 3 are not aligned in the same direction. As described above, a plurality of sheets are mounted on the carrier holding means 4 while changing the position for each predetermined number of sheets, and the flow of the raw material gas through the gap formed between the inner wall of the reaction tube 7 and the semiconductor wafer 3 is distributed around the entire circumference of the semiconductor wafer 3. It was made to be almost uniform over the entire length.

[0015]

When a plurality of semiconductor wafers 3 are mounted on the carrying holding means 20 and housed in the reaction tube 7, the carrying holding means 2 is provided.
The gap adjusting member 21 provided at 0 makes the gap in the vicinity of the cutout portion 3A of the semiconductor wafer 3 almost the same as the gap other than this vicinity so that the gap around the entire circumference of the semiconductor wafer 3 becomes substantially uniform. As a result, it is possible to realize a thin film forming apparatus in which the flow velocity of the source gas flowing on the outer circumference of the semiconductor wafer 3 is substantially uniform over the entire circumference. As a result, the film formation rate on the surface of the semiconductor wafer 3 becomes substantially uniform, and a thin film having a more uniform thickness can be formed on the surface of the semiconductor wafer 3 as compared with the conventional case.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1 in which parts corresponding to those in FIG. 12 are designated by the same reference numerals, numeral 20 indicates a quartz boat which is wholly housed in the reaction furnace 5 of the low pressure CVD apparatus, and a flow rate adjusting column 21 made of quartz is vertically arranged. It is bridged between a pair of disks 9 and 10 in parallel with the columns 11 to 14.

As shown in FIG. 2, the flow rate adjusting column 21 is attached to the back of the sides 9B and 10B of the peripheral portions of the disks 9 and 10 opposite to the sides 9A and 10A into which the wafer 3 is inserted. As shown in FIG. 3, the flow rate adjustment support column 21 has a crescent-shaped cross section, and the crescent-shaped flat surface portion 21A faces the side where the wafer 3 is inserted.
As a result, the flow rate adjusting column 21 is configured such that the flat surface portion 21A keeps a constant distance from the orientation flat 3A when facing the orientation flat 3A.

In the above structure, when forming a thin film on a plurality of wafers 3, all the wafers 3 are mounted on the quartz boat 20 with the orientation flats 3A facing the flow rate adjusting columns 21 (FIG. 3). In this state, it is housed in the reaction furnace 5 as shown in FIG.

In the quartz inner tube 7, a quartz boat 20 is provided.
The flow rate adjustment support 21 is the orientation flat 3A.
The clearance through which the reaction gas passes is made narrower than that of the conventional quartz boat 4 so as to be substantially the same as the clearance in the outer peripheral portion other than this vicinity. As a result, the flow velocity of the reaction gas flowing on the outer circumference of the wafer 3 becomes substantially the same over the entire circumference, and a thin film having a more uniform thickness is formed on the surface of the wafer 3 as compared with the conventional case. Further, when the reaction gas is flowing, the quartz boat 20 does not rotate inside the quartz inner tube 7.

Here, the uniformity F of the thickness of the thin film is expressed by the following equation when the maximum film thickness is Max and the minimum film thickness is Min.

[Equation 1] Can be expressed as The uniformity of the thin film when using the conventional quartz boat 4 was about ± 5% to ± 10%. On the other hand, the uniformity of the thin film when using the quartz boat 20 is ±
It will be 5% or less.

According to the above construction, when a plurality of wafers 3 are mounted on the quartz boat 20 and housed in the quartz inner tube 7, the flow rate adjusting column 21 provided on the quartz boat 20 allows the orientation flare. By making the gap in the vicinity of the chamber 3A substantially the same as the gap other than this vicinity so that the gap in the entire circumference of the wafer 3 becomes substantially uniform, the flow velocity of the reaction gas flowing in the outer circumference of the wafer 3 becomes uniform in the entire circumference. Becomes almost uniform. As a result, the film forming rate on the surface of the wafer 3 becomes substantially uniform, and a thin film having a more uniform thickness can be formed on the surface of the wafer 3 as compared with the conventional case.

Further, it is not necessary to rotate the quartz boat 20 while the reaction gas is flowing, and thus the reaction furnace 5 can have a simple structure without the rotation mechanism portion 8 of the quartz boat 4. Further, by eliminating the rotating mechanism portion 8, it becomes easier to maintain the airtightness in the reaction furnace as compared with the conventional case.

In the above embodiment, the quartz boat 20 is provided with the flow rate adjusting column 21 in order to adjust the flow velocity of the reaction gas in the vicinity of the orientation flat 3A. However, the present invention is not limited to this. Not limited to this, as shown in FIG. 5, only the facing portion 30A of the inner surface of the quartz inner tube 30 that faces the orientation flat 3A has a planar shape, and the orientation flats 3A are aligned. The gaps on the outer circumference of the wafer 3 when the plurality of wafers 3 are housed in the quartz inner tube 30 may be made uniform. Also in this case, the flow velocity of the reaction gas on the outer periphery of the wafer 3 becomes substantially uniform as a whole, and the same effect as described above can be obtained.

Further, in the above embodiment, the quartz boat 20 is provided with only the flow rate adjusting support 21 in order to make the clearance near the orientation flat 3A through which the reaction gas passes substantially the same as the clearance other than this vicinity. Although the present invention is not limited to this, the present invention is not limited to this, and as shown in FIGS. 6 to 8 in which parts corresponding to those in FIGS. A plurality of auxiliary plates 42 having the same shape as the crescent-shaped part cut out to form the orientation flats 3A at the same intervals are attached, and the straight parts 42A of the auxiliary plates 42 are attached to the orientation flats 3A. Abutting each wafer 3
By mounting a plurality of wafers 3 in the quartz boat 40, the outer peripheral gaps of the plurality of wafers 3 housed in the inner quartz tube 7 may be made substantially uniform over the entire circumference. Also in this case, the flow velocity of the reaction gas around the wafer 3 is substantially uniform over the entire circumference, and the same effect as described above can be obtained.

Furthermore, in the above-mentioned embodiment, the case where the flow rate adjusting support column 21 has a crescent-shaped cross section has been described, but the present invention is not limited to this, and FIG. 9 in which the same parts as in FIG. As shown, the present invention can be applied to the case where the facing portion 51A of the flow rate adjusting column 51 of the quartz boat 50 facing the orientation flat 3A has a curved shape.

Further, in the above-mentioned embodiment, the case where the flow rate adjusting column 21 is provided in the quartz boat 20 has been described, but the present invention is not limited to this, and as shown in FIG. It is also possible that the orientation of the orientation flats 3A is reversed 180 ° for each one when they are mounted, and the quartz boat 4 is housed in the reaction furnace 5 in this state. Also in this case, the flow velocity of the reaction gas on the outer circumference of the wafer 3 is substantially uniform over the entire circumference, and the same effect as described above can be obtained.

Further, in the above-mentioned embodiment, the case where the present invention is applied to the low pressure CVD apparatus has been described. However, the present invention is not limited to this, and the reaction furnace of the reaction furnace in the state where a plurality of wafers are mounted on the carrying holding means is described. It can be widely applied to a CVD apparatus in which a thin film is formed on each wafer by storing it inside and flowing a raw material gas into this reaction furnace.

[0029]

As described above, according to the present invention, when a plurality of semiconductor wafers are mounted on the carrying / holding means and housed in the reaction tube, the gap adjusting member provided on the carrying / holding means serves to secure the semiconductor wafers. By making the gap near the cutouts almost the same as the gaps other than this neighborhood so that the gaps around the entire circumference of the semiconductor wafer are substantially uniform, the flow velocity of the raw material gas flowing around the circumference of the semiconductor wafer becomes equal to the circumference. It is possible to realize a thin film forming apparatus that is substantially uniform over the entire length. As a result, the film forming rate on the surface of the semiconductor wafer becomes substantially uniform, and a thin film having a more uniform thickness can be formed on the surface of the semiconductor wafer as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a front view showing a quartz boat according to an embodiment of a thin film forming apparatus according to the present invention.

FIG. 2 is a side view thereof.

FIG. 3 is a sectional view for explaining a quartz boat.

FIG. 4 is a cross-sectional view for explaining a state of a gap between a wafer housed in a quartz inner tube and a periphery thereof.

FIG. 5 is a cross-sectional view showing a state of a gap between a wafer housed in a quartz inner tube and its periphery according to another embodiment.

FIG. 6 is a front view showing a quartz boat according to another embodiment.

FIG. 7 is a side view thereof.

FIG. 8 is a cross-sectional view of the quartz boat viewed from the VIVI cross section.

FIG. 9 is a sectional view showing a quartz boat according to another embodiment.

FIG. 10 is a schematic diagram showing a mounted state of a wafer according to another embodiment.

FIG. 11 is a schematic diagram showing a CVD apparatus.

FIG. 12 is a perspective view for explaining a reaction furnace in a CVD apparatus.

FIG. 13 is a front view for explaining a conventional quartz boat.

FIG. 14 is a side view thereof.

FIG. 15 is a cross-sectional view of the quartz boat viewed from the XIII XIII cross section.

FIG. 16 is a cross-sectional view showing a state of a conventional gap between a wafer housed in a quartz inner tube and its periphery.

[Explanation of symbols]

1 ... Low pressure CVD apparatus, 2 ... Heater section, 3 ... Wafer, 3A ... Orientation flat, 4, 20,
40, 50 ... Quartz boat, 5 ... Reactor, 6 ... Quartz outer tube, 7, 30 ... Quartz inner tube, 8 ... Rotation mechanism section, 9,
10 ... Disk, 11-14 ... Strut, 15 ... Reinforcing rib, 16 ... Slot, 21, 51 ... Flow rate adjusting strut, 21A ... Plane section, 30A, 51A ... Opposing section, 4
1 ... Support, 42 ... Auxiliary plate, 42A ... Straight part.

Claims (5)

[Claims] 1. A gap formed between an inner wall of the reaction tube and the semiconductor wafer, in which a carrying holding member, on which a plurality of semiconductor wafers each having a cutout portion are mounted, is positioned at a predetermined position in the reaction tube. In a thin film forming apparatus for forming a thin film on the surface of the semiconductor wafer by pouring a raw material gas onto the surface of the semiconductor wafer through a through hole, a gap is formed between the cutout portion of the semiconductor wafer and the inner wall of the reaction tube. An apparatus for forming a thin film, wherein an adjusting member is arranged to make a gap between the outer circumference of the semiconductor wafer and the inner wall of the reaction tube substantially uniform over the entire circumference. 2. The gap adjusting member is a rod-shaped member having a facing surface that faces the notches of the plurality of semiconductor wafers mounted on the carrying holding member in common, and the facing surface has a facing surface. The thin film forming apparatus according to claim 1, wherein the thin film forming apparatus is arranged on the carrying holding member so as to form a gap at a predetermined interval between the cutout portions of the plurality of semiconductor wafers. 3. The gap adjusting member is brought into contact with each notch portion of each of the plurality of semiconductor wafers mounted on the carrying holding member with substantially no gap, thereby cutting each of the plurality of semiconductor wafers. The thin film forming apparatus according to claim 1, wherein the thin film forming apparatus is arranged on the carrying holding member so as to be close to the original shape having no notch. 4. The gap adjusting member has an opposing surface that is commonly opposed to the cutout portions of the plurality of semiconductor wafers mounted on the carrying holding member, and the opposing surface has a plurality of the opposing surfaces. The thin film forming apparatus according to claim 1, wherein the thin film forming apparatus is arranged on the inner wall of the reaction tube so as to form a predetermined gap between the semiconductor wafer and the cutout portion. 5. A gap formed between an inner wall of the reaction tube and the semiconductor wafer by positioning a carrying holding member on which a plurality of semiconductor wafers each having a cutout portion are mounted at a predetermined position in the reaction tube. In a thin film forming apparatus for forming a thin film on the surface of the semiconductor wafer by injecting a raw material gas onto the surface of the semiconductor wafer through a predetermined number of sheets so that the cutout portions of the semiconductor wafer are not aligned in the same direction. A plurality of the carrier holding means are mounted to make the flow of the source gas through the gap formed between the inner wall of the reaction tube and the semiconductor wafer substantially uniform over the entire circumference of the semiconductor wafer. Thin film forming apparatus.