JPH08195353A - Boat cover of semiconductor manufacturing device - Google Patents

Abstract

PURPOSE: To enhance a thin film formed on a wafer (substrate) in uniformity and to especially prevent a part of the film formed on the periphery of the wafer from increasing in thickness. CONSTITUTION: A boat cover 30 provided with vent holes 34 through which reactive gas flows is provided so as to cover a boat 32 which holds wafers 6 to process in a semiconductor manufacturing device, wherein the inner face of the boat cover 30 confronting the boat 32 is roughened 35 to be enhanced in surface area, reaction product (thin film) is more deposited thereon so as to be less deposited on the peripheral part of the wafer 6 where reaction product is liable to deposit more, whereby a film deposited on the wafer 6 is lessened in thickness difference between the center and the peripheral part and enhanced in thickness uniformity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly to a boat cover for covering a boat holding a substrate to be processed.

[0002]

2. Description of the Related Art In a semiconductor manufacturing apparatus, a substrate to be processed such as a semiconductor wafer or a glass substrate is subjected to a thin film forming process by a CVD method (chemical vapor deposition method) or the like. There are various types such as those that perform diffusion processing. In such a semiconductor manufacturing apparatus, in order to improve manufacturing efficiency, a large number of substrates to be processed are collectively held in a boat, the boat is loaded into the device, and a predetermined process is performed on a large number of substrates at one time. Has been done.

FIG. 4 shows a vertical CV as a semiconductor manufacturing apparatus.
An example of the D device is shown. This CVD apparatus includes a cylindrical heater 2 having a heating element 1, a soaking tube 3 housed inside the heater 2, and a reaction tube 4 housed inside the soaking tube 3.
And a vertical boat 5 that holds a large number of wafers 6 to be processed in the reaction tube 4. A gas introduction pipe 7 is connected to the upper end of the reaction pipe 4, and a reaction gas supply pipe 8 from a reaction gas supply source (not shown) is connected to the gas introduction pipe 7. An exhaust port 9 is provided at the lower end of the reaction tube 4, and an exhaust pipe 10 is connected to the exhaust port 9.

The boat 5 can be loaded with the wafers 6 in a horizontal state in multiple stages with gaps. In this state, a large number of wafers 6 can be loaded.
Are held in the reaction tube 4. Boat 5 is boat cap 1
It is mounted on the elevator cap 12 via the 1 and can be moved up and down by an elevator (not shown). Therefore, the loading of the wafer 6 into the reaction chamber 4 and the removal from the reaction chamber 4 are performed by moving the boat 5 up and down by the operation of the elevator.

The formation of a thin film on the wafer 6 loaded in the reaction tube 4 is carried out by heating the heating element 1 to heat the reaction tube 4 via the soaking tube 3, and to supply the reaction gas supply tube 8 and the reaction gas introduction tube. The reaction gas is introduced into the reaction tube 4 via the gas 7, and is exhausted from the reaction tube 4 via the exhaust port 9 and the exhaust tube 10 to form a thin film on the surface of the wafer 6. Then, when taking out the film-formed wafer 6, the heating by the heater 2 is stopped and the exhaust port 9 is removed.
The exhaust is continuously performed, the temperature in the reaction tube 4 is lowered to a predetermined temperature, and then the elevator is operated to pull out the boat 5 from the reaction tube 4.

Here, the uniformity of the thin film formed on the wafer 6 greatly affects the performance of the semiconductor device manufactured from the wafer 6, and one of the factors that greatly affects the uniformity of this thin film is the reaction. There is a flow of reaction gas in the tube 4. In order to improve the flow of the reaction gas, it has been conventionally practiced to use a cover boat 21 having a cover 20 as the boat 5 as shown in FIG. The cover boat 21 has a boat portion and a cover portion that cover the boat portion integrated with each other.
On the inner surface of 0, a plurality of racks 22 forming a boat portion are provided extending in the vertical direction. Therefore, in the cover boat 21, the wafer 6 is engaged with the step portion of the rack 22 to hold a large number of wafers 6, and the periphery of the held wafer 6 is covered with the cover 20.

A large number of through holes 23 extending in the vertical direction are formed in the cover 20, and the reaction gas is allowed to flow through the through holes 23 into the cover 20. Therefore, when the wafer 6 is held by the cover boat 21 and loaded into the reaction tube 4, the reaction gas is passed through the through hole 2
Flowing through the cover boat 21 through 3, the flow of the reaction gas is relaxed, and the uniformity of the thin film formed on the surface of the wafer 6 is enhanced.

[0008]

Here, as a mode in which the uniformity of the thin film is impaired, the film thickness at the peripheral portion of the wafer 6 becomes significantly larger than that at the central portion in many cases. Against this, although the cover boat 21 is effective to some extent, it is recognized that the closer the cover 20 is to the peripheral edge of the wafer 6, the more the tendency that the film thickness at the peripheral edge of the wafer becomes large is alleviated. Therefore, it is desirable to bring the cover 20 close to the peripheral edge of the wafer 6.

However, if the cover 20 is too close to the peripheral edge of the wafer 6, the wafer 6 may come into contact with the cover 20 during transport of the cover boat 21 or during processing in the reaction tube 4, causing damage to the wafer 6 or reaction. Accidents such as disturbing the gas flow and excessively depositing reaction products will occur. Therefore, in the conventional cover boat 21, there is a problem that the cover 20 cannot be brought close to the peripheral edge of the wafer 6 and the countermeasure for reducing the film thickness on the peripheral edge portion of the wafer 6 cannot be sufficiently performed.

The present invention has been made in view of the above conventional circumstances, and provides a semiconductor manufacturing apparatus capable of effectively preventing the uniformity of a thin film formed on a substrate (wafer), particularly the increase of the film thickness at the peripheral portion of the substrate. Intended to provide boat covers.

[0011]

According to the boat cover of the present invention, the effect of reducing the film thickness with respect to the peripheral portion of the substrate (wafer) is that the reaction product (thin film) is deposited on the inner surface of the cover facing the wafer. In order to achieve the above object, in order to achieve the above-mentioned object, the reaction gas is supplied to the boat holding the substrate processed by the semiconductor manufacturing apparatus. In a boat cover provided with a through hole for circulation and covering the boat, an inner surface of the boat cover facing the boat is formed with an uneven surface. The boat cover of the present invention may be integrally formed with the boat like the above-described cover boat, or may be attached to the boat when used as a separate body from the boat.

[0012]

When the boat cover of the present invention is used to cover the boat, the inner side surface of the boat cover, which is the uneven surface, faces the peripheral edge of the substrate held by the boat. That is, the inner surface of the boat cover has an uneven surface, so that the surface area is enlarged as compared with the case where it is a flat surface.
A large amount of reaction products (thin films) are deposited. Since more reaction products are deposited on the boat cover side in this way, the amount of deposition on the peripheral portion of the substrate is reduced, the thin film on the peripheral portion is thinned, and the uniformity of the film thickness with the central portion of the substrate is reduced. Is increased.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A boat cover according to an embodiment of the present invention will be described below with reference to the drawings. The boat cover of this embodiment is integrated with the boat to form a cover boat as shown in FIG. 5, and the vertical CVD as shown in FIG.
Used by being loaded into the device. The cover boat 31 includes a cylindrical boat cover 30 and a plurality of racks 3 that form a boat portion extending in the vertical direction on the inner surface of the cover 30.
2 is provided. The cover 30 is vertically divided into halves, and when these are combined and fastened with fasteners (not shown), a cylindrical integral boat cover 30 whose ends are surrounded by a top plate 30a and a bottom plate 30b is formed. The boat cover 30
A stand portion 33 is attached to the bottom plate 30b of the above, and the stand portion 33 mounts the stand portion 33 on the boat cap 11.

A large number of through holes 34 extending in the vertical direction are formed in the side plate 30c of the boat cover 30, and the reaction gas is allowed to flow into the cover 30 through these through holes 34. The rack 32 is a side plate 30c between the through holes 34.
Is attached to the inner side surface of the wafer, and a large number of stepped portions for engagingly holding the wafer 6 are arranged in the vertical direction. Therefore, the cover boat 31 holds a large number of wafers 6 by engaging the wafer 6 with the step portion of the rack 32, covers the held wafers 6 with the cover 30, and passes through the through holes 34 in the cover 30. The reaction gas is distributed.

A large number of protrusions 35 are formed on the inner surface of the side plate 30c of the boat cover, and the inner surface of the boat cover 30 facing the boat (that is, the peripheral portion of the wafer 6) is an uneven surface. ing. In this embodiment, as shown in FIG. 3, the protrusions 35 are formed in a hemispherical shape, and the fine protrusions 35 are spread over the side plate 30c.
It increases the surface area of the inner surface. That is, considering a surface having four sides of length L, the area of this surface is (L × L) when it is a flat surface. On the other hand, when (n × n) pieces of hemispherical projections 35 having a diameter R are spread, the area of this surface becomes (L × L) + (n2 × π × R2) / 4, which is smaller than that of a flat surface. , (N 2 × π × R 2) / 4 surface area increases.

Although the cover boat 31 is generally made of quartz having high heat resistance, the side plate 3 made of this quartz is used.
If the inner surface of 0c is sandblasted or the like, it is possible to easily form a large number of fine projections 35 as described above. In addition, the material of the cover boat 31 is silicon carbide (S
If iC) is used, the surface becomes uneven due to the property of silicon carbide, so that the inner surface of the side plate 30c can be made uneven without any special processing.

The wafer 6 is placed on the cover boat 31 having the above structure.
In order to hold the wafer, the cover 30 is divided into halves, the wafers 6 are sequentially engaged with the stepped portions of the rack 34, and then the halved covers 30 are combined and fixed. Further, when the wafer 6 is taken out from the cover boat 31, the reverse operation may be performed. Then, in order to form a thin film on the wafer 6, the wafer 6 is held in the cover boat 31 and loaded into the reaction tube 4, the reaction tube 4 is heated, and the reaction gas is circulated through the through hole 34 into the cover 30. To do. At this time, as in the conventional example, the cover 30 reduces the flow of the reaction gas and enhances the uniformity of the thin film formed on the surface of the wafer 6.

Further, since the inner surface of the boat cover 30 facing the peripheral edge of the wafer 6 is enlarged by the projection 35, a relatively large amount of reaction product (thin film) is deposited on this inner surface. For this reason, the concentration of the reaction gas in the vicinity of the peripheral portion of the wafer 6 relatively decreases, and the amount of the reaction product deposited on the peripheral portion of the wafer 6 decreases. As a result,
The increase in the film thickness at the peripheral portion of the wafer, which tends to be larger than that at the central portion of the wafer 6, is reduced, and the difference in the film thickness between the central portion and the peripheral portion of the wafer 6 is reduced, resulting in uniform film thickness. A high thin film is produced.

In the above embodiment, the boat cover 30
Although the cover boat 31 in which the boat cover (rack 32) is integrally formed is shown, the boat cover of the present invention may be separately provided from the boat, and may be assembled to the boat at the time of use. Further, in the above-mentioned embodiment, the example applied to the vertical type semiconductor manufacturing apparatus has been shown, but the present invention is not limited to this, and can also be applied to the horizontal type semiconductor manufacturing apparatus.

The present invention can be applied not only to a boat that holds a large number of substrates but also to a boat that holds one substrate at a time. The shape of the boat cover of the present invention is not particularly limited, and various shapes other than the cylindrical shape are set according to the shape of the boat. Further, the number, shape, and position of the reaction gas passage holes formed in the boat cover are not particularly limited, and the point is that a necessary and sufficient reaction gas can be passed through the boat cover.

Further, in the above embodiment, the inner surface of the boat cover is provided with a hemispherical projection to form an uneven surface. However, the shape and size of the projection, or the method of forming the uneven surface is not limited to this and various changes are made. It is possible to increase the surface area as an uneven surface. It should be noted that when the protrusions or concavities are formed on the concavo-convex surface, the protrusions or concavities preferably have a curved surface such as a spherical surface. By doing so, cleaning can be performed during maintenance work. When carrying out, the reaction product deposited on the inner surface of the boat cover can be easily peeled off.

[0022]

As described above, according to the boat cover of the present invention, since the inner surface of the boat cover facing the boat is formed by the uneven surface, the reaction product is formed on the inner surface of the boat cover facing the substrate. The amount of the reaction product that is deposited and relatively deposited on the peripheral portion of the substrate is reduced. Therefore, even if the boat cover is not very close to the substrate, the thin film on the peripheral portion of the substrate, which tends to increase the amount of reaction products deposited, becomes thin, and the difference in film thickness between the central portion and the peripheral portion of the substrate becomes small. ,
A highly uniform thin film can be formed on the substrate as a whole.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a cover boat according to an embodiment of the present invention.

FIG. 2 is a cross-sectional plan view of a cover boat according to an embodiment of the present invention.

FIG. 3 is a perspective view illustrating an effect of an uneven surface.

FIG. 4 is a cross-sectional view showing an example of a vertical semiconductor device.

FIG. 5 is an exploded perspective view of a cover boat according to a conventional example.

[Explanation of symbols]

 5 Boat 6 Wafer 30 Boat Cover 31 Cover Boat 32 Rack 34 Through Hole 35 Protrusion (Uneven Surface)

Claims (1)

[Claims] 1. A boat cover provided with a through hole for allowing a reaction gas to flow therethrough and covering the boat for holding a substrate to be processed by a semiconductor manufacturing apparatus, the boat cover being opposed to the boat. A boat cover for a semiconductor manufacturing apparatus, wherein an inner surface is formed as an uneven surface.