JPH11145125A - Chemical vapor deposition film-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for forming a CVD film whose thickness and quality over the entirety thereof, specifically at the periphery and at the central portion of a wafer, are uniform. SOLUTION: There is provided with a device for forming a film by chemical vapor deposition, comprising a quartz boat 40 on which a wafer is mounted being supported by supporting members at the peripheral edge thereof and conveyed to a process chamber. A starting gas is introduced into the process chamber which accommodates the quartz boat 40 mounting the wafer, so as to form a CVD film on the wafer by chemical vapor deposition. This chemical vapor deposition film-forming device is of a vertical type, and the supporting members of the quartz boat 40 therein are constituted of quartz poles 42 having supporting grooves 46 to which the peripheral edge of the wafer is inserted so as to be horizontally supported thereby. Every portion of the individual quartz poles 42, in which the supporting groove 46 is formed, is thinly shaped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a CV on a surface of a semiconductor substrate such as a semiconductor wafer by using a chemical vapor deposition method.
More specifically, the present invention relates to a chemical vapor deposition apparatus for forming a D film, and more specifically, to a CV film having a uniform film thickness and film quality over the entire surface of a wafer.
The present invention relates to a chemical vapor deposition apparatus for forming a D film, for example, a silicon oxide film or a silicon nitride film on a wafer.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device, various CVD films are formed on a substrate by using a chemical vapor deposition (Chemical Vapor Deposition) method. For example, a normal-pressure C
There are various types such as a VD device, a low pressure CVD device, and a plasma CVD device.

Referring to FIG. 5, the configuration of a conventional vertical reduced pressure type chemical vapor deposition apparatus (hereinafter, LPCVD apparatus) used for performing a low pressure chemical vapor deposition method will be described.
FIG. 5 is a schematic longitudinal sectional side view showing the configuration of the LPCVD apparatus. The conventional LPCVD apparatus 10 includes a vertical quartz outer tube 14 containing a quartz cylindrical inner tube 12 therein, and a quartz outer tube 14.
And a heater 16 for heating the quartz outer tube 14 and a vacuum pump 18 for exhausting the remainder of the reaction gas from the outer tube 14 to maintain a predetermined vacuum pressure.
With. Further, the outer tube 14 has a gas introduction injector 20 for feeding a reaction gas into the inner tube 12 and an exhaust port 22 connected to the vacuum pump 16 at a lower portion of the side wall. A detachable manifold 24 is attached to the lower end of the outer tube 14. The manifold 24 is detached, and a quartz boat 26 that horizontally holds a number of wafers W as a film formation object is placed in the inner tube 12. It is designed to be sent. The quartz boat 26 is supported on the manifold 24 via a cap 28. The heater 16 includes an upper heater unit 16A, a middle heater unit 16B, and a lower heater unit 16C which are provided sequentially from top to bottom.

As shown in FIG. 6, the quartz boat 26 has a plurality of vertical quartz columns 32 arranged at substantially equal intervals so as to surround the periphery of the wafer over a length shorter than a half circumference of the wafer.
And a ring-shaped connecting ring 34 for connecting the quartz columns 32. A support groove 36 extending in the horizontal direction is provided inside each quartz column 32 to support the peripheral portion of the wafer.
It is provided as shown in (a) and (c). When forming a CVD film, the wafer W accommodated in the quartz boat 26
As shown in FIGS. 6B and 6C, the wafer is held by inserting the peripheral portion of the wafer into the support groove. Here, FIG.
FIG. 6A is a perspective view showing a configuration of a quartz boat provided in a conventional chemical vapor deposition apparatus, FIG. 6B is a plan view of the quartz boat, and FIG. It is sectional drawing which shows a wafer support groove.

When a CVD film is formed on a wafer, the wafer W is placed horizontally in a quartz boat
Then, the material gas is introduced into the inner tube 12 heated by the above-described method, and then is sucked by the vacuum pump 16 to be in a reduced pressure state, and the material gas is introduced. As a result, chemical vapor deposition occurs on the wafer W, and a CVD film is formed on the wafer W.

[0006]

What is important in forming a CVD film is to form a uniform film with a uniform thickness over the entire surface of the wafer. For example, if the uniformity of the CVD film in the wafer surface is poor, the exposure operation performed in the subsequent process is restricted, and it is difficult to satisfy the requirements such as uniform optical constants of the film. However, in the conventional LPCVD apparatus, there is a problem that the film thickness becomes thin around the wafer.
There was a problem that the product yield was low. In the above description, the LPCVD apparatus has been described as an example.
A similar problem occurs in a normal pressure CVD apparatus other than the apparatus. Accordingly, an object of the present invention is to provide a film having the same film thickness and film quality as the central portion of the wafer over the entire surface of the wafer, especially around the wafer.
An object of the present invention is to provide an apparatus for forming a VD film.

[0007]

SUMMARY OF THE INVENTION The present inventor has investigated the cause of the difficulty in maintaining uniformity in a wafer surface around a wafer with a conventional LPCVD apparatus when forming a CVD film. I found That is, in the conventional quartz boat 26, at the time of film formation, the source gas does not reach the periphery of the wafer due to the influence of the quartz column 32. As a result, as shown in FIG. W _C and the thin peripheral region W _P of the film thickness occurs. In other words, it was found that the presence of the quartz column 32 hindered the growth of the CVD film maintaining the uniformity within the wafer surface, and the thickness of the CVD film became insufficient at the peripheral portion. Then, the inventor considered to reduce the influence of the wafer supporting portion by locally reducing the contact portion between the wafer and the quartz column, and completed the present invention through repeated experiments.

In order to achieve the above object, a chemical vapor deposition apparatus according to the present invention supports a peripheral portion of a mounted wafer with a supporting member, and transfers and holds the wafer into a process chamber. Chemical vapor deposition apparatus for forming a CVD film on a wafer by chemical vapor deposition by introducing a source gas into a process chamber containing a quartz boat on which a wafer is mounted In the above, the support member of the quartz boat is characterized in that the size of the support member is reduced at a portion in contact with the wafer peripheral portion, so that the raw material gas can easily approach the wafer peripheral portion. In the present invention, since the support member of the quartz boat has a small size of the support member at the contact portion between the wafer peripheral portion and the support member, it is possible to prevent the source gas from reaching the wafer peripheral portion as in the related art. As a result, the growth of the CVD film is maintained uniformly over the entire surface of the wafer, and the thickness of the CVD film is uniform over the entire surface of the wafer including the peripheral portion of the wafer.

In a preferred embodiment of the present invention, the chemical vapor deposition apparatus is of a vertical type, and a support member of the quartz boat is spaced apart so as to surround the peripheral portion of the wafer over a length not more than half a circumference of the wafer. It has a plurality of arranged vertical columns and a horizontally extending support groove provided on the inner surface of the vertical column, and inserts a wafer peripheral portion into the support groove to support the wafer in the horizontal direction. In addition, the vertical column is thinner at each portion where the support groove is formed.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment Example This embodiment is an example of an embodiment of a chemical vapor deposition apparatus according to the present invention. FIG. 1A shows a chemical vapor deposition apparatus of this embodiment. FIG. 1B is a schematic perspective view showing a configuration of the quartz boat provided, and FIG. 1B is a cross-sectional view of a quartz column in a support groove forming portion. Except for the quartz boat, the chemical vapor deposition apparatus of this embodiment is a conventional LPC shown in FIG.
This is an LPCVD apparatus having the same configuration as the VD apparatus. This LPC
As shown in FIG. 1A, the quartz boat 40 provided in the VD apparatus includes a plurality of vertical boats arranged at substantially equal intervals so as to surround the peripheral portion of the wafer over a length shorter than a half circumference of the wafer. It includes a quartz column 42 and a ring-shaped connecting ring 44 connecting the quartz columns 42, and a support groove 46 extending in the horizontal direction is provided inside each quartz column 42 in order to support the peripheral portion of the wafer. It is. Then, in the quartz boat 42 of the present embodiment, the quartz pillar 42 is locally thinned at the contact portion where the support groove 46 is formed, for each support groove 46, as shown in FIG.

In the present embodiment, with the above-described structure, the flow of the raw material gas near the contact portion between the wafer W and the quartz column 42 is closer to the quartz column 42 and the peripheral portion of the wafer as shown in FIG. It becomes a flow 48. As a result, the supply shortage of the raw material gas on the peripheral portion of the wafer that hinders the growth of the CVD film is greatly reduced, and the uniformity of film formation on the wafer W is as shown in FIG. The region W _C is greatly expanded, and the region W _P having a small thickness is reduced to a minimum.
Therefore, the present embodiment is an example of the conventional LPCVD shown in FIG.
A CVD film having excellent in-wafer uniformity can be formed on a wafer as compared with the in-wafer uniformity of the apparatus.

On the other hand, when the conventional quartz boat 26 is used, the flow 50 of the raw material gas is as shown in FIG.
Since the gas flows away from the quartz column 32, the supply of the source gas onto the wafer W around the quartz column 32 is hindered, and the film growth is hindered. As a result, the uniformity of film formation on the wafer surface is deteriorated as shown in FIG.

[0013]

According to the present invention, the chemical vapor deposition apparatus is provided with a quartz boat in which the size of the supporting member at the portion in contact with the peripheral portion of the wafer is reduced.
By making the source gas easily accessible to the peripheral portion of the wafer, the uniformity of the film thickness and film quality in the wafer surface can be improved. The present invention is a very effective means especially when the required standard for film formation such as uniformization of the optical constant of the film due to the restriction of the exposure operation as a post-process becomes more severe.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a quartz boat provided in a chemical vapor deposition apparatus of this embodiment.

FIG. 2 is a gas flow chart for explaining a gas flow of a raw material gas when the quartz boat shown in FIG. 1 is used.

FIG. 3 is a view for explaining uniformity of a CVD film in a wafer surface when the quartz boat shown in FIG. 1 is used.

FIG. 4 is a gas flow chart for explaining a gas flow of a source gas in a conventional chemical vapor deposition film forming apparatus.

FIG. 5 is a schematic cross-sectional vertical side view showing a configuration of an LPCVD apparatus.

6 (a) is a perspective view showing a configuration of a quartz boat provided in a conventional chemical vapor deposition apparatus, FIG. 6 (b) is a plan view of the quartz boat, and FIG. 6 (c) is This is a wafer support groove of the quartz column of the quartz boat.

FIG. 7 shows a CV formed by using a conventional LPCVD apparatus.
FIG. 3 is a diagram illustrating the uniformity of a D film in a wafer surface.

[Explanation of symbols]

10: Conventional LPCVD apparatus, 12: Inner tube made of quartz, 14: Outer tube made of quartz, 1
6 ... heater, 16A ... upper heater unit, 16
B: Middle heater unit, 16C: Lower heater unit, 18: Vacuum pump, 20: Gas introduction injector, 22: Exhaust port, 24: Manifold, 2
6 ... Quartz boat, 28 ... Cap, 32 ... Quartz pillar, 34 ... Connecting ring, 36 ... Support groove, 40 ... Quartz boat, 42 ... Quartz pillar, 44 ... Connecting ring, 46 ... Support groove, 48: flow of raw material gas, 50: flow of raw material gas.

Claims (2)

[Claims] 1. A quartz boat, which supports a wafer peripheral portion of a loaded wafer with a support member and feeds and holds the wafer into the process chamber, and feeds the raw material into the process chamber containing the quartz boat loaded with the wafer. Introduce gas,
In a chemical vapor deposition apparatus for depositing a CVD film on a wafer by a chemical vapor deposition method, a support member of a quartz boat is reduced in size at a portion in contact with a peripheral portion of the wafer, and a raw material gas is formed. A chemical vapor deposition film-forming apparatus characterized in that it is easy to approach the wafer periphery. 2. The chemical vapor deposition apparatus according to claim 1, wherein the supporting member of the quartz boat is provided with a plurality of vertical members separated and arranged so as to surround a peripheral portion of the wafer over a length not more than a half of the wafer. A column, and a horizontally extending support groove provided on an inner side surface of the vertical column, wherein a wafer peripheral portion is inserted into the support groove to support the wafer in a horizontal direction, and the vertical column supports the wafer. 2. The chemical vapor deposition apparatus according to claim 1, wherein each of the grooves is thinned.