JPH07183222A - Device and method for heat treatment - Google Patents

Abstract

PURPOSE:To obtain a heat-treating device which can improve the yield of semiconductor devices by carrying semiconductor wafers in and out of a boat with less amounts of dust adhering to the wafers and, at the same time, which can uniformly form films on the wafers by providing first to third boat covering bodies and a wafer carrying device to the heat-treating device. CONSTITUTION:A heat-treating device is provided with first boat covering bodies 25 and 27 which are installed to a boat 11 and cover the circumference of a wafer train at prescribed intervals and first opening 28 which are installed to the covering bodies 25 and 2 and have widths wider than the diameter of wafers 10. The heat-treating device is also provided with second openings 29 in the covering bodies 25 and 27 which have widths narrower than those of the sections 28. In addition, the heat-treating device is also provided with a wafer carrying device 17 having a projection which limits the movement of the wafers 10 to the front end side of an arm 16 at the front end section of the arm 16 which supports and carries the wafers 10 and second and third boat covering bodies 34 and 36 which respectively cover the first and second openings 28 and 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus.

[0002]

2. Description of the Related Art In a low pressure CVD apparatus, when a plurality of semiconductor wafers accommodated in a boat are subjected to a film forming process, the film thickness of the peripheral edge of the semiconductor wafer is thicker than that of the central part of the semiconductor wafer. As a process in which the in-plane film thickness uniformity cannot be processed satisfactorily, a film containing impurities is formed. For example, forming an oxide film by high temperature LP-CVD,
There is deposition of a doped polysilicon film. A so-called cage boat is widely used as one method for improving the film formation uniformity during the heat treatment. This basket boat covers the periphery of a boat containing semiconductor wafers with a quartz cylinder, which is provided with a large number of film formation gas flow holes and slits. When a film-forming process is performed using the basket boat, a gas component with a vigorous reaction is deposited on the surface of the quartz cylinder, but a gas component with a relatively mild reaction is discharged from the hole into the cylinder. It is possible to enter inside and form an in-plane uniform film on the surface of a semiconductor wafer.

In order to improve the uniformity of the film formation on the surface of the semiconductor wafer, it is desired to keep the distance between the semiconductor wafer and the quartz cylinder constant and to reduce the distance. Therefore, for example, as disclosed in Japanese Utility Model Laid-Open No. 2-131549, a part of the tubular portion is integrally attached to the boat. Also,
Regarding the transfer of semiconductor wafers, a hole is provided on the contact surface of the transfer arm that supports the semiconductor wafer, and this hole is evacuated by a vacuum pump to hold the semiconductor wafer by vacuum suction on the transfer arm. It is carried and transferred. On the other hand, in recent years, the degree of integration of semiconductor elements has been improved by microfabrication, and 4M is currently mass-produced in DRAM, and at the same time, development of mass-production technology for higher integration of 16M and 64M is underway. For that purpose, how to reduce the adhesion of dust to the semiconductor wafer has become an important issue.

[0004]

In the transfer of semiconductor wafers, vacuum suction has a function of accurately and reliably holding the semiconductor wafer on the transfer arm. However, due to the strength of the vacuum suction force, the semiconductor wafer becomes scratched, causing dust to be generated, or attracting dust floating around when vacuum suction is applied, causing the vacuum suction surface of the semiconductor wafer to A certain amount of dust adheres to the back side. An improvement point that the dust re-suspends in the subsequent process and re-attaches to the surface side of the semiconductor wafer, or re-attaches to the surface of another semiconductor wafer to reduce the yield of the finally completed semiconductor element. was there.

That is, in the basket type boat in which the quartz cylindrical portion is integrally attached to the boat described in the above document, when the semiconductor wafer is accommodated in the basket type boat by the transfer arm using vacuum adsorption, Although the film uniformity can be favorably processed, there is an improvement point that the yield of semiconductor elements with little dust adhesion cannot be improved. The present invention has been made in view of the above points, the semiconductor wafer has less dust adhesion, is carried in and out of a boat, improves the yield of semiconductor elements, and a heat treatment apparatus capable of uniformly forming a film on a semiconductor wafer, and It is intended to provide a heat treatment method.

[0006]

According to a first aspect of the present invention, in a heat treatment apparatus provided with a boat cover for covering a plurality of rows of semiconductor wafers accommodated in a boat at a predetermined interval, the heat treatment apparatus is provided in the boat, A first boat cover body that covers the periphery at a predetermined interval, and a width wider than the wafer diameter,
A first opening provided in the first boat cover body and a side opposite to the first opening provided over the entire wafer accommodation area of the boat and having a width narrower than that of the first opening. A second opening provided in the first boat cover body over the entire wafer accommodating region of the boat and a tip of an arm for mounting and transporting the wafer, the tip of the arm being the wafer. And a second boat cover body that covers the first opening portion and the second opening portion, respectively, and a third boat cover body that covers the first opening portion and the second opening portion, respectively. It is a heat treatment apparatus characterized by the above.

Further, the second and third boat cover bodies are mounted on the boat. Further, the second and third boat cover bodies are mounted on the heat treatment apparatus.

A second aspect of the present invention is a heat treatment method in which a plurality of wafers are accommodated in a boat whose periphery is covered with a boat cover at predetermined intervals and heat treated, and the wafers are placed on an arm of a transfer mechanism. The arm is inserted from a first opening having a width wider than the width of the wafer provided in the boat, and the second opening having a width narrower than the width of the wafer is provided at a position facing the first opening. Loading the wafer into the boat by projecting the tip of the wafer into the boat, and covering the first opening and the second opening with a boat cover, respectively.
And a step of subjecting the wafers accommodated in the boat to a predetermined heat treatment.

[0009]

According to the heat treatment apparatus and heat treatment method of the present invention,
Since the semiconductor wafer is placed on the arm of the transfer mechanism and transferred, and the semiconductor wafer is carried in and out of the boat, the adhesion of dust is significantly less than when using a vacuum chuck, and the defective element of the semiconductor wafer after heat treatment By the boat cover that covers the row of semiconductor wafers, a gas component that is active in the film forming process is formed on the surface of the boat cover, and a relatively gentle gas component of the reaction is generated in the semiconductor in the boat cover. Since the film is formed on the wafer surface, it is possible to perform a film forming process with good in-plane uniformity of the semiconductor wafer.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the apparatus of the present invention is applied to a vertical heat treatment apparatus will be specifically described below with reference to the drawings. As shown in FIG. 1, a reaction tube 1 made of a heat-resistant material such as quartz, which is cylindrical and has an upper end closed and an opening provided at the lower end to form a reaction vessel, is provided. An inner tube 2 made of a heat-resistant material, for example, quartz, having an open upper end and a lower end, is coaxially provided inside. An elastic seal member such as O
A manifold 4 made of a corrosion resistant metal, for example, stainless steel is provided via a ring 3, processing gas introducing pipes 5 and 6 are connected to a side surface of the manifold 4, and an exhaust pipe is provided to the side surface. 7 is connected,
The inside of the reaction tube 1 can be exhausted to a predetermined degree of vacuum by an exhaust pump (not shown).

A heating means, for example, a cylindrical resistance heater 8 having at least three zones is provided to cover the periphery of the reaction tube 1, and the inside of the reaction tube 1 is heated to a desired heat treatment temperature, for example, 500 to 1000. It is configured so that it can be appropriately set in the range of ° C. A plurality of objects to be processed, such as semiconductor wafers 1, which are subjected to a predetermined heat treatment in the reaction tube 1.
0 is stacked and accommodated in the boat 11 at a predetermined interval, and the boat 11 is placed on the heat retaining cylinder 12 and the heat retaining cylinder 1
2 is mounted on a rotating mechanism 14 provided on a lid 13 that covers the opening of the reaction tube 1, while rotating the semiconductor wafer 10 housed in the boat 11 at a predetermined speed, It is configured so that a predetermined heat treatment can be performed.

Further, an elevating mechanism 15 for elevating and lowering the row of semiconductor wafers 10 accommodated in the boat 11 together with the lid 13 and loading / unloading into / from the reaction tube 1 is provided. As shown in FIG. 2, a wafer transfer device 17 provided with an arm 16 for mounting and transporting the semiconductor wafer 10 is provided adjacent to the elevating mechanism 15, and the wafer transfer device 17 is configured as shown in FIG. As indicated by the arrow 2, the semiconductor wafer is moved in the up-down direction, the forward-backward direction, and rotated, and the semiconductor wafer is gravity-loaded from the semiconductor wafer storage container (not shown) on the arm 16 to store the predetermined semiconductor wafer in the boat 11. It is configured so that it can be transferred to another section.

The boat 11 is made of quartz, which is a heat-resistant and corrosion-resistant material, and as shown in FIG. 3, the semiconductor pillars 24 are provided on the four square pillars 20, 21, 22, and 23, respectively, so that the semiconductor pillars are made of quartz. The wafer 10 is configured to accommodate a plurality of wafers 10 in a substantially horizontal state, for example, 120 wafers, and the boat cover member 2 is provided on the outer periphery of the columns 20 and 21.
5 is a predetermined distance from the semiconductor wafer 10, for example, 10 mm
They are spaced apart and welded to the columns 20 and 21,
The boat cover member 25 is provided with a plurality of slits 26 each having a width of 8 mm in the vertical direction, and the reaction gas can enter and exit through the slits 26. Further, as shown in FIG. 3, the columns 22 and 23 are also integrally formed by welding the boat cover member 27.

An opening 28 is provided in the boat 11 over the entire area of the semiconductor wafer accommodating region of the boat 11 which is wider than the width of the semiconductor wafer, and the semiconductor wafer 10 is carried in and out of the boat 11 through the opening 28. The wafer transfer device 17 is arranged on the front side of the opening 28. Further, an opening 29 is provided in the boat 11 on the side facing the opening 28, and when the semiconductor wafer is placed on the arm 16 of the wafer transfer device 17 and loaded into the boat 11, the boat The cover members 25, 27 and the tip of the arm 16 do not interfere with each other.

FIG. 4 shows the semiconductor wafer 1 on the boat 11.
The figure shows a state in which the arm 16 on which 0 is placed is inserted. The arm 16 enters from the opening 28 side and the tip of the arm 16 projects to the opposite opening 29 side. FIG. 5 is a cross-sectional view of the arm 16. The arm 16 is, for example, a rectangular plate-like body, is provided with a recess 30 for housing the semiconductor wafer 10, and the arm 16 has a tip end portion. In this embodiment, a convex portion 31 having a guiding function is provided along the peripheral edge of the supported wafer so that the semiconductor wafer 10 is not displaced on the arm 16 in the forward direction of the arm 16. Therefore, the wafer transfer device 17 can store the semiconductor wafer 10 in the recess 30 of the arm 16 and transfer it accurately to the boat 11 without vacuum suction.

As shown in FIG. 6, in the opening 28 of the boat 11 accommodating the semiconductor wafer 10, a boat cover member 34 is formed by vertically dividing a cylinder provided with a half-moon shaped member 33 at the upper end thereof. However, the half-moon shaped member 33 is placed on the upper end of the boat 11, and the boat cover member 34 is configured to cover the opening 28.
The boat cover member 34 is configured to be mounted on the semiconductor wafer 10 at a predetermined distance, for example, 10 mm. In addition, in the opening 29, similar to the above,
A flat boat cover member 36 provided on the upper end portion of the half-moon shaped member 35 extends the half-moon shaped member 35 into the boat 1.
The boat cover member 36 is mounted on the upper end of the boat 1 to cover the opening 29 with the boat cover member 36. The boat cover member 36 and the orientation flat portion 37 of the semiconductor wafer 10 accommodated in the boat 11 are connected to each other. It is configured to face each other and be mounted at a predetermined interval, for example, an interval of 10 mm.

The boat cover member 34 is provided with a slit 38 for passing the processing gas in the vertical direction, and the boat cover member 36 may be appropriately provided with a slit as required. FIG. 7 shows a state in which the boat 11 is housed in the reaction tube 1, and the semiconductor 10
Is the boat cover member 2 provided on the boat 11.
5, 27 and the boat cover members 34 and 36 surround the periphery, and they are housed in the inner tube 2 in the reaction tube 1. At this time, the semiconductor wafer 10 including the orientation flat portion 37,
Boat cover members 25, 27, 3 around the periphery at equal intervals
Since it is covered with Nos. 4 and 36, a uniform film forming process can be performed.

Further, the rotating mechanism 14 can be used to perform the film forming process while rotating the boat 11 if necessary. The heat treatment apparatus is configured as described above. Next, the operation of the semiconductor wafer transfer and the film forming process will be described. By the wafer transfer device 17, the semiconductor wafer 10 is placed on the arm 16 and carried out from a wafer storage container (not shown) such as a wafer cassette. Next, the wafer transfer device 17 is driven in the vertical direction and the rotation direction to be positioned in front of a predetermined loading position of the boat 11 shown in FIG. 2, and the arm 16 is moved forward to move the semiconductor wafer accommodating position of the boat 11 by, for example, 2 mm. Bring it up and stop. Next, the wafer transfer device 17 is driven to drive the arm 16
Is lowered by, for example, about 4 mm, the semiconductor wafer 10 is placed on the four wafer supporting protrusions 24 of the boat 11, and the semiconductor wafer 10 is transferred from the arm 11 to the boat 11. Then, by retreating the arm 16, the transfer of one semiconductor wafer 10 is completed.

Thereafter, this operation is repeated until the boat 1
1 contains, for example, 120 semiconductor wafers. Next, the half moon members 33, 35 of the boat cover members 34, 36
Is mounted on the upper end portion of the boat 11, so that the boat cover members 34, 36 are inserted into the openings 28, 29 of the boat 11.
Put on. Then, the boat 11 is accommodated in a predetermined heat treatment area in the reaction tube 1 by raising the elevating mechanism 15.

A case of forming a silicon oxide film by heat treatment, for example, CVD at 820 ° C. will be described below. By appropriately controlling the electric power applied to each zone of the three-zone heater 8, the temperature of at least the region in which the semiconductor wafers 10 are arranged in the reaction tube 1 is constantly set within 820 ° C. ± 1 ° C.

From the gas introduction pipes 5 and 6, nitrous oxide (N
₂ O) 1000 SccM, Monomoran (SiH ₄ ) 12
5SccM was inserted into the reaction tube 1, and the inside of the exhaust pipe was set to a pressure of 0.8 Torr by an exhaust pump (not shown).
A film forming process is performed for a predetermined time. At this time, the periphery of the semiconductor wafer 10 is covered with the boat cover members 25, 27, 34, 36 at substantially equal intervals. Then, by rotating the rotating mechanism 14, the boat accommodating the semiconductor wafer 10 and the boat cover members 25, 27, 34, 36 are integrally rotated in the inner pipe 2, whereby the processing gas introducing pipe 5, 6
The processing gas discharged from the boat cover members 25, 2
It can be uniformly taken into 7, 34, 36 and the nonuniformity of the film forming process can be greatly improved.

Since the boat cover member 36 is arranged in a flat plate shape so as to face the row 37 of the orientation flat portion, the silicon oxide film is subjected to the CVD process in a batch process under the above conditions.
The film thickness uniformity of the semiconductor wafer after film formation is ±
It was good within 3%. As comparative data, in the case where the boat cover member 36 is not a flat plate shape but a cylinder is divided vertically and the distance between the orientation flat portion 37 and the boat cover member 36 changes from 10 mm to 15 mm, the same as above. When the film was formed under the conditions, the in-plane uniformity of the film thickness of the semiconductor wafer was deteriorated to ± 4 to ± 5%.

Since the so-called soft landing method, in which the semiconductor wafer is placed on the arm 11, is used for the adhesion of dust accompanying the transfer of the semiconductor wafer, 120 semiconductor wafers are transferred to the boat 11 and the original The number of attached dust particles per wafer when housed in a wafer cassette is 0.2 μφ
The above particles had a small value of 5 or less. As comparative data, when a semiconductor wafer was transferred by a vacuum suction type wafer transfer device, particles of 0.2 μφ or more were significantly increased to 30 to 50 under the same conditions as above.

The fork for transferring the semiconductor wafer is
Not only one, but one with five forks,
You may transfer five semiconductor wafers collectively. Alternatively, the pitch conversion mechanism may be provided on the five fork mechanisms to transfer the semiconductor wafer between the accommodation pitches of the wafer cassette and the accommodation pitch of the boat.

FIG. 8 shows another embodiment. A boat cover member 40 provided corresponding to the opening 28 of the boat 11 has a half-moon shaped member 41 at the upper end of the boat cover member 40. The boat cover member 40 is provided along the inner side of the inner pipe 2 by placing the half-moon shaped member 41 at a predetermined position on the upper end portion of the inner pipe 2. There is. Also, the boat 11
The boat cover member 42 provided so as to correspond to the opening 29 is provided with a half-moon shaped member 43 at the upper end of the boat cover member 42.
When the inner pipe 2 is placed at a predetermined position on the upper end of the
The boat cover member 40 is arranged along the inner side of the.

Then, the semiconductor wafers 10 accommodated in the boat 11 are carried into the inner pipe 2 by the elevating mechanism 15 so that the openings 28, 2 of the boat 11 are carried out.
The boat cover members 40 and 42 are arranged so as to correspond to item No. 9. In the case of this example, the boat 11 could not be rotated, but the film formation uniformity was good, within ± 3%, which was almost the same as when the boat 11 was rotated. In addition, the boat cover members 40 and 42 are attached to the inner pipe 2.
Assembling at the time of maintenance by welding
Workability such as removal and cleaning can be improved.

The same parts as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof is omitted. FIG. 9 shows still another embodiment, in which the boat 11 which is turned sideways is mounted on a mounting table 50, and an opening 51 is provided in the center of the mounting table 50. Below the opening 51, the semiconductor wafer is composed of a holding portion 52 having holding grooves for holding the semiconductor wafer vertically at a predetermined interval, and an elevating / lowering drive portion 53 for elevating the holding portion 52. A wafer push-up device 54 is arranged. Above the boat 11, a wafer gripping device including two wafer grips 55 and 56 and an opening / closing drive unit 57 that opens and closes the wafer grips 55 and 56 is arranged.

Next, the case of transferring the semiconductor wafer 10 to the boat will be described. The second opening 2 of the boat 11 will be described.
The holding unit 52 of the wafer thrusting apparatus is lifted from 9 to hold the semiconductor wafer 10 vertically in the holding groove of the holding unit 52 and receive the semiconductor wafer 10 from the boat 11. Then, by further raising the holding part 52, the raising of the holding part 52 is stopped at a predetermined wafer holding position of the wafer holding device 58. Next, the two wafer gripping portions of the wafer gripping device 58 are closed so as to hold the semiconductor wafer 10, and the semiconductor wafer 10 is received by the wafer gripping device. And
The transfer operation of the semiconductor wafer 10 is completed by lowering the holding portion 52 of the wafer thrusting device 54.

When the number of semiconductor wafers to be transferred is large,
Further, the above steps may be repeated. The same parts as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof is omitted. The present invention is not limited to the above-mentioned embodiments, and can be used for film formation processing by CVD, which is difficult to improve the in-plane uniformity of a semiconductor wafer such as a phosphorus-added polysilicon film and a boron-added silicate glass film. . Further, the film forming process is not limited to CVD, but may be an oxidation process or a diffusion process, and may be applied to any process as long as it is a process that handles a gas flow, such as an etching process.

[0030]

As described above, according to the present invention, the adhesion of dust to the semiconductor wafer is small, the semiconductor wafer can be transferred to the boat, and the in-plane uniformity of the semiconductor wafer is excellent. Film formation can be performed, and thus the yield of semiconductor elements can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view illustrating a heat treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating the wafer transfer device of FIG.

FIG. 3 is a partially enlarged perspective view of FIG. 2 seen from another angle.

FIG. 4 is a state diagram in which the semiconductor wafer of FIG. 3 is loaded into a boat.

5 is a cross-sectional view of FIG.

FIG. 6 is an explanatory view of the boat cover member of FIG. 1.

FIG. 7 is an explanatory view of the relationship between the semiconductor wafer of FIG. 1 and a boat cover member.

FIG. 8 is an explanatory view of a boat cover member according to another embodiment.

FIG. 9 is an explanatory diagram of semiconductor wafer transfer when a boat according to another embodiment is horizontally placed.

[Explanation of symbols]

 1 Reaction Tube 10 Semiconductor Wafer 11 Boat 16 Arm 17 Wafer Transfer Device 25, 27, 34, 36, 40, 42 Boat Cover Member 26 Slit

Claims (4)

[Claims] 1. A heat treatment apparatus provided with a boat cover for covering a plurality of rows of semiconductor wafers accommodated in a boat at predetermined intervals, the first heat treatment apparatus being provided on the boat and covering the periphery of the wafer rows at predetermined intervals. A boat cover body, a first opening provided in the first boat cover body, which is wider than the wafer diameter and covers the entire wafer accommodation area of the boat, and a side facing the first opening. Is provided in
A second opening having a width narrower than that of the first opening and provided on the first boat cover body over the entire wafer accommodating region of the boat, and a tip of an arm for mounting and transporting the wafer. A wafer transfer device provided with a convex portion that restricts the movement of the wafer in the direction of the tip of the arm;
A heat treatment apparatus comprising a second boat cover body and a third boat cover body that respectively cover the first opening portion and the second opening portion. 2. The second and third boat cover bodies,
The heat treatment apparatus according to claim 1, wherein the heat treatment apparatus is mounted on the boat. 3. The second and third boat cover bodies,
The device is mounted on the heat treatment apparatus.
The heat treatment apparatus described. 4. A heat treatment method in which a plurality of wafers are accommodated in a boat whose periphery is covered by a boat cover at predetermined intervals and heat treated, and the wafers are mounted on an arm of a transfer mechanism and provided on the boat. The first end of the arm is inserted into the first opening having a width wider than the width of the wafer, and the distal end of the arm is projected into the second opening having a width narrower than the width of the wafer provided at a position facing the first opening. And carrying the wafer into the boat, covering the first opening and the second opening with a boat cover, and subjecting the wafer accommodated in the boat to a predetermined heat treatment. Heat treatment method.