JPH0745547A - Heat treatment device - Google Patents

Abstract

PURPOSE:To enable the total length of a treated body boat to be minimized or the process margin to be widened by mounting the treated bodies on the boat at uneqaul pitches. CONSTITUTION:Within the title heat treatment device wherein a treated body boat 10 wherein plural treated bodies W are arranged at a specific pitch as well as plural dummy treated bodies DW are also arranged at the specific pitch on both sides of the treated bodies W is contained in a treating vessel 8, for the heat treatment the pitch L1 of the dummy treated bodies DW is set up to be smaller than the pitch L2 of the treated bodies W thereby enabling the level of the treated body boat 10 to be cut down for making the title heat treatment device compact.

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 for heat treating a semiconductor wafer or the like.

[0002]

2. Description of the Related Art In general, a heat treatment apparatus is used as an apparatus for subjecting an object to be processed such as a semiconductor wafer to a predetermined heat treatment in a uniform temperature state to form a thin film on the surface or perform heat diffusion.

A heat treatment apparatus of this type will be described with reference to FIG. 5. This heat treatment apparatus 2 has a processing container 8 having an inner tube 4 made of quartz and an outer tube 6 concentrically arranged with the inner tube 4. In this, a large number of quartz wafer boats 10,
For example, about 100 or 150 stacked semiconductor wafers W as the objects to be processed are housed in the elevator 12 so that they can be inserted and removed.

A stainless steel manifold 18 having a processing gas supply pipe 14 and a gas exhaust pipe 16 is connected to the lower portion of the processing container 8, and a stainless steel cap portion 20 is hermetically sealed at the lower end opening. It is possible. The wafer boat 10 is mounted on the cap portion 20 via a heat insulating cylinder 22 made of quartz for heat insulation. A heater part 24 for heating the container 8 is wound around the outer periphery of the processing container 8 along the height direction thereof, and constitutes a heating furnace as a whole.

The temperature control and the flow of processing gas when heat-treating a wafer are very important factors for the quality of film formation, for example. Each wafer is heated under the same conditions and exposed to the processing gas under the same conditions. Is preferred. For this reason, in the wafer boat 10, dummy wafer zones 26A and 26B are provided at the upper and lower ends of the stacking zone of the semiconductor wafer W to be the final product, and the pitch is the same as the pitch of the previous product wafer W in this zone. A plurality of dummy wafers DW are stacked on the upper and lower sides, for example, about 10 sheets at a pitch. Therefore, the product wafer W and the dummy wafer DW are all stacked at an equal pitch. As a result, the dummy wafer D is processed against the process gas rising in the inner tube 4.
By first contacting W, the gas flow is rectified so that the gas contact conditions for each wafer located in the product wafer zone are made substantially the same, and at the same time, the heat capacity at the wafer portions located at both ends of the product wafer zone is set to the wafer zone center. By making the portions substantially the same, the thermal responsiveness and the like are also set to the same condition, and the heat treatment quality between wafers is made uniform.

[0006]

By the way, the larger the pitch L1 of the wafer W is, the better the wraparound of the processing gas is, the more uniform the contact state with the gas is between the wafer surfaces, and the increase in the process temperature. Even when the temperature is high, the temperature difference between the central portion and the peripheral portion of the wafer can be reduced due to the heat radiation, and the occurrence of slips and the like can be suppressed. However, if the pitch L1 is increased more than necessary, the wafer boat 10 can be prevented. Since it becomes longer and the height of the entire processing apparatus becomes too high, in the present situation, for example, the pitch L1 is set to about 4.76 mm in the case of a 6-inch wafer, and about 6.35 mm in the case of an 8-inch wafer. Is set to.

However, the height of the wafer boat 10 as described above is considerably large, and the height of the clean room in which this apparatus is installed is limited, so that more wafers can be processed by the wafer boat of the same length. It is strongly desired to further improve the throughput.

The present invention focuses on the above problems,
It was created to solve this effectively. It is an object of the present invention to provide a heat treatment apparatus in which the pitch of dummy processing objects that are not used in products is reduced.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention installs a plurality of objects to be processed at a predetermined pitch and a plurality of dummy objects on both sides of the installed objects to be processed. In the heat treatment apparatus for accommodating the object boat in which the object to be processed is installed at a predetermined pitch in the processing container and performing the heat treatment on the object to be processed, the pitch of the dummy object to be processed, The pitch is set smaller than the pitch of the object to be processed.

[0010]

Since the present invention is constructed as described above, the pitch of the portion for accommodating the dummy object to be treated is smaller than the pitch of the portion to accommodate the object to be treated as a product. For example, the pitch of the dummy object to be processed is set to the pitch of the minimum width that can be transferred by the transfer mechanism that transfers the dummy object, and thereby the height of the object boat and the height of the object boat can be maintained while maintaining the same throughput. It is possible to reduce the height of the entire device. Further, at the same boat height, the pitch of the dummy object to be processed is minimized, and the pitch of the product object to be processed is changed depending on the region (zone), whereby the process margin can be increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat treatment apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an embodiment of a heat treatment apparatus according to the present invention, FIG. 2 is a view showing a state in which a target object is transferred to a target object boat by using a transfer mechanism, and FIG. 3 is a target object. It is a front view showing a boat. The same parts as those of the conventional device are designated by the same reference numerals.

As shown in the figure, the heat treatment apparatus 26 has a processing container 8 which is made of, for example, quartz and is formed into a cylindrical shape, the upper end portion of which is closed and the lower end portion of which is open. An outer cylinder 6 made of quartz and having a ceiling with an open upper end, and a cylindrical inner cylinder 4 having a cylindrical upper end and being concentrically arranged inside, for example, having an open upper end. Then, in the inner tube 4, a plurality of processing target boats made of, for example, quartz, for example, semiconductor wafers W stacked on the wafer boat 10 in a vertical direction at a predetermined pitch are removably accommodated. Has been done.

A heater part 24 is provided on the outer periphery of the processing container 8 so as to be coaxially wound around the process container 8 in a spiral shape, and the outer periphery of the heater part 24 is made of, for example, stainless steel via a heat insulating material 28. A cylindrical outer shell 30 made of steel is provided, and constitutes a heating furnace 32 as a whole.

A cylindrical manifold 18 made of, for example, stainless steel is connected to the lower end of the processing container 8. An annular flange portion 18A is formed on the upper end portion of the manifold 18, and the lower end flange portion 6A of the outer tube 6 is airtightly supported on the flange portion 18A via an O-ring 40, for example.

The manifold 18 has its inner protruding portion 1
The lower end of the inner pipe 4 is supported by 8B, while a processing gas supply pipe 14 for introducing a processing gas is connected to the manifold 18 with its tip extending to the inner side of the inner pipe 4. A gas exhaust pipe 16 connected to a vacuum pump (not shown) is connected between the outer pipe 6 and the inner pipe 4 so as to communicate with each other.

The wafer boat 10 is mounted on a heat retaining cylinder 22 made of, for example, quartz, which exhibits a heat insulating function, and the heat retaining cylinder 22 is hermetically sealed at the lower end opening of the manifold 18 via an O-ring 36. It is rotatably supported by a cap portion 20 made of, for example, stainless steel that seals as much as possible. The cap portion 20 is held by an elevating mechanism, for example, an elevator 12, so that the wafer boat 10 can be loaded / unloaded into / from the inner pipe 4.

As shown in FIG. 2, the elevator 12 can be moved up and down with high accuracy by a ball screw 38, for example.
Guided by. The transfer of the wafer W to the wafer boat 10 that is moved up and down by the elevator 12 is performed by a transfer mechanism 42 arranged in parallel near the wafer W. The transfer mechanism 42 has an elevator 48 which can be vertically moved by a ball screw 46 while being guided by two guide rails 44, and a tip end of the elevator 48 can be turned by a turning motor 50. The turning arm 52 is provided, and the turning arm 52 is provided with a wafer holding arm 54 which is slidable in the longitudinal direction thereof, and holds the wafer W at its tip.

On the other hand, the wafer boat 1 characterized by the present invention
0 is provided with a plurality of support rods 58 made of quartz, for example, four quartz support rods 58, which are bridged between two disc-shaped end plates 56, 56 (for simplification in FIG. 3, 2), and a wafer holding groove 60 for holding a wafer at a predetermined pitch is formed on the support rod 58. The wafer boat 10 has dummy wafer regions 62 and 64 for holding and holding a plurality of dummy wafers DW as dummy processing objects at the upper and lower ends thereof, and is narrowed to these two dummy wafer regions 62 and 64. A product wafer area 66 for mounting and holding a wafer W to be a product in a curved shape is formed.

The pitch L1 of the wafer holding mechanism 60 in each dummy wafer area 62, 64 is determined by the product wafer area 66.
Is set smaller than the pitch L2 of, for example, the pitch L1
Is set to about 5 mm and the pitch L2 is 6.35.
It is set to about 13 mm. That is, in the product wafer area 66, the wafers W are stacked and mounted at an equal pitch of the pitch L2, and the upper and lower dummy wafer areas 62 and 64 are arranged.
In, the dummy wafers DW are stacked and mounted at an equal pitch of the pitch L1. In the illustrated example, several dummy wafers DW are described in each of the dummy wafer regions 62 and 64. However, in the case of an 8-inch wafer, the dummy wafer regions 62 and 64 have 10 to 10 dummy wafers, respectively. About 15 dummy wafers DW are placed on the product wafer area 66.
Since about 50 to 150 wafers W are stacked and placed on the wafer, the length of the wafer boat as a whole can be shortened.

In this case, the pitch L1 of the wafer holding groove 60 in the dummy wafer area 62 which is not used as a product.
Is set to have the minimum transferable pitch of the transfer mechanism 42 for transferring wafers (including dummy wafers). That is, in order to suppress the entire length of the wafer boat 10 as much as possible, it is preferable to make the pitch L1 as small as possible within a range in which the wafer can be transferred by the transfer mechanism 42. Further, the pitch L2 of the wafer holding grooves 60 in the product wafer area 66 does not cause a slip due to the temperature difference between the central portion and the peripheral portion of the wafer when the temperature of the wafer is raised, and adversely affects the processing gas within the wafer surface. As a limit value within the range not given, for example, 6.3 as described above.
It is set to about 5 mm.

Next, the operation of this embodiment configured as described above will be described. First, the transfer mechanism 42 transfers the unprocessed semiconductor wafer W and the dummy wafer DW to the corresponding regions of the wafer boat 10. That is, about 15 product wafers W are placed in the product wafer area 66.
About zero wafers are placed, and ten dummy wafers DW are placed on the upper and lower dummy wafer regions 62 and 64, respectively, for a total of about twenty wafers. In this way, the wafer boat 10 containing the wafers and the dummy wafers is loaded into the processing container 8 by the elevator 12, and the opening of the manifold 18 is sealed by the cap 20.

Next, the temperature of the processing container 8 which has been preheated to about 400 ° C. is raised to the process temperature, for example, about 850 ° C. by increasing the power of the heater section 24. Then, while supplying a predetermined amount of processing gas from the processing gas supply pipe 14, the gas exhaust pipe 16 is evacuated by a vacuum pump (not shown) to set the inside of the processing container 8 to a predetermined pressure, for example, about 0.5 Torr. In this case, since about 10 dummy wafers DW are stacked on the upper and lower ends of the product wafer W, the heat capacity and radiation conditions in the product wafer region 66 are substantially the same over the entire region 66, The product wafers W placed in this region have substantially the same temperature conditions across the surfaces.

Further, the processing gas introduced into the furnace through the processing gas supply pipe 14 rises in the gap between the heat insulating cylinder 22 and the inner wall 4, and the dummy wafer region 6 below the wafer boat 10 is reached.
The dummy wafer DW placed on the wafer No. 4 is brought into contact with the dummy wafer DW, and the rectified processing gas is brought into contact with the product wafer W provided in the product wafer region 66 to form a film by the reaction product. This processing gas further rises, changes its direction at the ceiling of the processing container 8, flows down between the inner tube 4 and the outer tube 6, and is evacuated from the gas exhaust tube 16. Here, in this embodiment, the pitch L1 of the wafer holding grooves 60 in the dummy wafer regions 62 and 64 located at the upper and lower ends of the wafer boat 10, that is, the pitch of the dummy wafer DW is made as small as possible, and the product wafer Since the wafer pitch L2 in the region 66 is set to an appropriate pitch corresponding to the heat treatment to be performed, the height of the wafer boat 10 itself can be shortened without adversely affecting the product wafer W. Therefore, the occupied volume of the entire apparatus can be reduced correspondingly, and the expensive clean room can be effectively used.

Further, when occupying the same volume as the conventional device, it is possible to improve the throughput by the amount of shrinking the dummy wafer regions 62 and 64. The wafer pitch is 6.35 in both the product wafer area and the dummy wafer area.
Although the conventional wafer boat has a total length of about 1113 mm when it is set to about 10 mm (in the case of 170 wafer holding grooves), according to the present embodiment, the total length of the wafer boat is about 10 mm.
It became about 92 mm, and it was possible to reduce the height considerably.

In the above embodiment, the groove pitch L2 of the product wafer area 66 is set to 6.35 using an 8-inch wafer.
Although the groove pitch L1 of the dummy wafer regions 62 and 64 is set to about 5.0 mm, the groove pitch L2 of the product wafer region 66 is optimally set depending on the type of heat treatment to be processed. The pitch is set, and is set to about 4.76 mm in the case of a 6-inch wafer, for example. Further, the groove pitch L1 of the dummy wafer regions 62 and 64
Is also defined by the minimum transfer pitch of the wafer transfer mechanism 42. Therefore, if the minimum transfer pitch of the transfer mechanism 42 becomes smaller, the dummy wafer area 6 is made to correspond to it.
The groove pitch L1 of 2 and 64 is also set small. For example, in the case of the current transfer mechanism, it can be set as small as about 4.8 mm.

The number of wafers accommodated in the product wafer area 66 is not limited to 150, but different numbers
For example, the present invention can be applied to a wafer boat accommodating 100 or 50 wafers. Further, in the above embodiment, the wafer pitches L2 in the product wafer area 66 are all set to the same value, for example, about 6.35 mm, but the present invention is not limited to this, and as shown in FIG. The wafer pitch L3 in some areas may be set to be slightly larger.
That is, since the lower portion of the wafer boat 10 is supported by the heat retaining cylinder 22 having a relatively large heat capacity, the heat capacity near the lower portion of the wafer boat 10 which comes into contact with the heat retaining cylinder 22 is lower than that of other wafer boat portions. It is getting bigger overall.

Therefore, the lower region of the wafer boat has a low thermal response, and therefore, especially when the wafer temperature is raised to the process temperature, a temperature difference of, for example, 60 ° C. between the peripheral portion of the wafer and the center thereof. May occur, and there is a risk that the wafer will undesirably slip due to the difference in thermal expansion at this time. In order to prevent this, as shown in FIG. 4, the pitch L3 of the wafer holding groove 60 in the region having a relatively large heat capacity, that is, the large heat capacity region 68, which is the lower part of the product wafer region 66, is set to the pitch L2 of the other part. It is set to a value slightly larger than, for example, about 8 to 9 mm. As a result, the wafer pitch in the large heat capacity region 68 is increased to increase the amount of radiant heat from the heater portion in the peripheral portion of the wafer to the central portion of the wafer. The difference is reduced and the occurrence of slip is suppressed. The number of wafers accommodated in the large heat capacity region 68 depends on the wafer size, but in the case of an 8-inch wafer, for example, about 20 to 25 wafers are stacked. Further, the groove pitch L1 of the dummy wafer region 64 below the wafer boat 10 is set as small as possible as in the case shown in FIG. 3 because the dummy wafer DW placed here is not related to the product. Reduce the height of the entire wafer boat.

In the above embodiments, the case where the pitch of the product wafer region is set to 6.35 mm or 8 to 9 mm has been described, but the present invention is not limited to this, and the process gas flow may vary depending on the process. Since the conditions such as squeeze and temperature difference within the wafer surface are tightened or alleviated, the values of the pitches L2 and L3 may be set larger or smaller correspondingly. Further, in the above-mentioned embodiments, the apparatus having the double pipe structure for performing the depressurization treatment has been described as an example, but the present invention is not limited to this, and the apparatus having the single pipe structure for performing the atmospheric pressure treatment or the vertical heat treatment apparatus. Not only it can be applied to a horizontal heat treatment apparatus.

[0029]

As described above, according to the heat treatment apparatus of the present invention, the following excellent operational effects can be exhibited. Since the pitch of the area for accommodating the dummy object to be processed is set smaller than the pitch of the other areas, the height of the entire object boat and the height of the entire apparatus can be reduced accordingly. Further, in the case of the same boat height, the process margin can be increased by minimizing the pitch of the dummy processing target area and changing the pitch of the product processing target area depending on the zone. Therefore, when the boats to be processed have the same height, the throughput can be improved by the reduction of the pitch.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a state in which a target object is transferred to a target object boat by using a transfer mechanism.

FIG. 3 is a front view showing a boat to be processed.

FIG. 4 is a front view showing another boat to be processed.

FIG. 5 is a sectional view showing a conventional heat treatment apparatus.

[Explanation of symbols]

 4 Inner Tube 6 Outer Tube 8 Processing Container 10 Wafer Boat (Processing Object Boat) 18 Manifold 22 Insulating Tube 26 Heat Treatment Device 42 Transfer Mechanism 58 Support Rod 60 Wafer Holding Groove 62, 64 Dummy Wafer Area 66 Product Wafer Area 68 Large Heat Capacity Area DW Dummy wafer (dummy processed object) W Semiconductor wafer (processed object) L1, L2 pitch

Claims (3)

[Claims] 1. A processing object boat in which a plurality of processing objects are installed at a predetermined pitch and a plurality of dummy processing objects are installed on both sides of the installed processing object at a predetermined pitch. In a heat treatment apparatus which is accommodated in a container and is configured to perform heat treatment on the object to be processed, the pitch of the dummy object to be processed is set to be smaller than the pitch of the object to be processed. Characterizing heat treatment equipment. 2. The object boat is placed on a heat retaining cylinder, and the pitch of a part of the object to be treated located on the heat retaining cylinder side is set to be larger than the pitch of the object to be treated in the other portion. The heat treatment apparatus according to claim 1, wherein: 3. The heat treatment according to claim 1, wherein the pitch of the dummy object is a length determined by a minimum transferable pitch of a transfer mechanism for transferring the dummy object. apparatus.