JPH08130192A - Thermal treatment equipment - Google Patents

Abstract

PURPOSE: To inhibit the extension of in-plane temperature difference while maintaining a temperature-rise rate at high speed, and to prevent the generation of a slip by optimally setting loading pitches in a loading jig, on which a plurality of semiconductor wafers are loaded in parallel in the vertical direction, in response to the temperatures of heat treatment. CONSTITUTION: A fixed number of semiconductor wafers W having a diameter of 250mm or more (such as 300mm) are loaded on a ladder board 10 as a loading jig arranged to the lower section of a thermal treatment equipment 1 at loading pitches of 10-40mm, the ladder board 10 is loaded in a reaction vessel 3 in a vertical type oven 2 for the thermal treatment equipment 1, and the semiconductor wafers W is heat-treated as specified. A fixed temperature in the heat treatment extends over 800 deg.C from 600 deg.C, and a temperature-rise process of 20 deg.C or higher at every minute is set in a temperature-rise process up to a temperature rise in the fixed-temperature atmosphere. Accordingly, the extension of the in-plane temperature difference of the wafers W is inhibited while maintaining a temperature-rise rate at a high temperature, so that the generation of a slip can be prevented.

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 manufacturing process of a semiconductor wafer (hereinafter referred to as "wafer") having a semiconductor device such as an LSI formed on its surface, an oxidation treatment for forming a silicon oxide film (SiO ₂ ) on the surface thereof. Alternatively, diffusion processing for diffusing impurities is performed, and when performing each of these treatments, a heat treatment apparatus has been often used conventionally. Conventionally, this type of heat treatment apparatus generally has a tubular furnace for heating, which is arranged vertically, and has a substantially tubular reaction vessel in which a reaction space is formed. A wafer to be processed is a ladder boat. A predetermined number (for example, 100) of quartz wafers are mounted on a quartz mounting jig in a horizontal state at intervals vertically, and the wafer boat is loaded / unloaded into the reaction vessel by an appropriate elevating mechanism. Is configured.

For example, in the case of a process for forming a silicon oxide film on the surface of a wafer, after the mounting jig having the wafer mounted thereon is loaded into a reaction container, the temperature inside the reaction container is required for a predetermined process. For example, O ₂ (oxygen) gas was introduced into the reaction vessel while being heated to 1000 ° C. to form an oxide film (SiO ₂ ) on the wafer surface.

By the way, the conventional mounting jig has a diameter of 200.
mm (8 inch) wafer
The mounting pitch was also set between about 6 and 10 mm.
As described above, this pitch is used to improve the throughput by collectively processing a large number of wafers, and in the process of raising the temperature inside the reaction vessel by the tubular furnace, the temperature difference (surface The internal temperature difference) is suppressed to prevent the occurrence of crystal defects called slip, and is mainly defined. That is, since the temperature of the wafer in the reaction vessel surrounded by the tubular furnace rises more rapidly at the peripheral edge than at the center when the temperature is raised, an in-plane temperature difference occurs during the temperature rise process. .

[0005]

The 200 mm diameter wafer described above is produced for use in, for example, a 16 M DRAM, but the integration will be further increased in the future, and a 256 M DRAM will be produced.
In order to efficiently manufacture (for example, the number of chips per chip is about the same as the present), the wafer diameter is inevitably increased to 250 mm (10 inches), 300 mm (12 inches).
The diameter of the wafer is needed.

However, when such a large-diameter wafer is heat-treated by the batch method, if the size of the above-mentioned conventional mounting jig is enlarged as it is and the mounting pitch is also set as it is, the in-plane temperature difference becomes large. The wafer may slip. In this case, if the rate of temperature rise in the reaction vessel is lowered, the expansion of the in-plane temperature difference can be suppressed to some extent, but this is not preferable because the throughput is reduced. Therefore, it is necessary to provide a means for maintaining a certain temperature rise rate and enabling batch processing.

The present invention has been made in view of the above points, and in heat-treating the above-mentioned wafers having a diameter of 250 mm or more by a batch method, while maintaining a high temperature rising rate, the in-plane temperature difference is enlarged. It is an object of the present invention to provide a heat treatment apparatus capable of suppressing the occurrence of slip and suppressing the occurrence of slip to solve the above problem.

[0008]

In order to achieve the above object, according to the present invention, the mounting pitch of a mounting jig for mounting a plurality of semiconductor wafers in parallel in the vertical direction is optimally set according to the temperature of heat treatment. A heat treatment apparatus is provided.

That is, according to the first aspect of the present invention, there is provided a substantially tubular reaction container located in the tubular furnace, and a mounting jig for mounting a plurality of semiconductor wafers in parallel in the vertical direction. In a heat treatment apparatus configured to deliver the mounting jig in this state into the reaction vessel and heat-treat the semiconductor wafer in a predetermined temperature atmosphere, the semiconductor wafer has a diameter of 250 mm or more, The predetermined temperature is 600 ° C. or more and less than 800 ° C., and the temperature rising process until the temperature is raised to the predetermined temperature atmosphere by the tubular furnace has a temperature rising process of 20 ° C. or more per minute. The heat treatment apparatus is provided in which the mounting pitch of the semiconductor wafer mounting jig is set to 10 to 40 mm.

Further, according to a second aspect of the present invention, a heat treatment apparatus which can cope with a case where the treatment temperature is higher than that of the first aspect is provided, and a substantially tubular reaction container located in a tubular furnace and a plurality of semiconductor wafers vertically are provided. A mounting jig that is mounted in parallel is provided, and a mounting jig in which a plurality of semiconductor wafers are mounted is delivered into the reaction container, and heat treatment is performed on the semiconductor wafer in a predetermined temperature atmosphere. In the heat treatment apparatus, the semiconductor wafer has a diameter of 250 mm or more, and the predetermined temperature is 800 ° C. or more and 1000 ° C.
The temperature is less than 20 ° C. per minute in the temperature rising process until the temperature is raised to the predetermined temperature atmosphere by the tubular furnace. Is set to 20 to 80 mm.

According to a third aspect of the present invention, there is provided an apparatus structure suitable for high-temperature processing, wherein a substantially tubular reaction vessel located in a tubular furnace and a mounting jig for vertically mounting a plurality of semiconductor wafers in parallel. In a heat treatment apparatus configured to deliver a mounting jig in a state in which a plurality of semiconductor wafers are mounted to the reaction container, and heat-treat the semiconductor wafers in a predetermined temperature atmosphere, The semiconductor wafer has a diameter of 250 mm or more, the predetermined temperature is 1000 ° C. or higher and less than 1100 ° C., and the temperature is raised to the predetermined temperature atmosphere by the tubular furnace, the temperature is increased to 20 minutes per minute. The semiconductor wafer is configured to have a temperature rising process of not less than ° C.
It is characterized by being set to 160 mm.

[0012]

According to the knowledge of the inventors, the occurrence of slip on the wafer is largely related to the yield value of the shear stress of silicon, which is the material of the wafer. It is also known that the yield shear stress greatly depends on the temperature of silicon. Figure 1 shows the IEEE "TRANSACTION ON S
EMICONDUCTOR MANUFACTURING '' Vol.1 No.3 (August 198
8) Research on yield stress of silicon, which was cited and introduced in “Macroscopic plastic properties of dislocation-f
ree germanium and other semiconductor crystals.I.
It is a graph which was created based on the conclusion described in "yield behavior" and which shows the relationship between the temperature and the yield shear stress of silicon.

According to this, the yield shear stress value sharply decreases from around 500 ° C, slightly decreases from 600 ° C to 800 ° C, and thereafter gradually decreases further gradually. Therefore, in view of such characteristics, it is understood that the yield stress value decreases as the treatment temperature increases, and therefore the allowable in-plane temperature difference in which slip does not occur is correspondingly small.

In the method of heating by the radiant heat from the tubular furnace, it is considered that the in-plane temperature difference can be reduced as the distance between the upper and lower wafers is increased, and as described above, the higher the temperature rising rate is, The in-plane temperature difference becomes large.
Further, in terms of productivity, the batch system has no merit unless the wafers can be processed efficiently as compared with the single-wafer system.

According to the heat treatment apparatus of claim 1, claim 2, and claim 3, which are constructed by the inventors under the above-mentioned background, the in-plane temperature difference does not cause a slip depending on the processing temperature. The wafer mounting pitch is given within the allowable temperature difference. The mounting pitch as referred to in the present invention is
The distance between the centers of the thicknesses of the upper and lower wafers, that is, in the wafer mounted in parallel in the vertical direction, between the upper end surface of a wafer and the upper end surface of the wafer mounted immediately above it. Say the distance.

That is, according to claim 1, the processing temperature is 60.
At 0 ° C or more and less than 800 ° C, the mounting pitch is such that slip does not occur. According to claim 2,
When the treatment temperature is 800 ° C. or higher and lower than 1000 ° C., slip does not occur, and in the case of the third aspect, the slip does not occur when the treatment temperature is 1000 ° C. or higher and lower than 1100 ° C. Moreover, the heat treatment apparatus according to any one of claims 1 to 3 has a heating rate of 2 per minute.
It allows the existence of a fast heating process above 0 ° C.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 2 shows an outline of a heat treatment apparatus 1 according to this embodiment, and FIG. 300mm silicon semiconductor wafer (hereinafter
"Wafers" W are mounted in a predetermined number, for example, 10 on a ladder boat 10 as a mounting jig arranged below the heat treatment apparatus 1, and a reaction container in the vertical furnace 2 of the heat treatment apparatus 1 is loaded. It is configured to be loaded into the inner part 3 and to be subjected to a predetermined heat treatment, for example, a silicon oxide film forming treatment.

The ladder boat 10 has a circular top plate 11 and a bottom plate 12 which are vertically opposed to each other, and three columns 13, 1 are provided between the top plate 11 and the bottom plate 12.
4 and 15 are provided. Then, the wafer W transferred by a transfer means (not shown) such as a transfer arm is mounted on the mounting members 16, 17, 18 fixed between the insides of the columns 13, 14, 15. Is mounted on the ladder boat 10.

The mounting members 16, 17, and 18 have the same shape and the same size. For example, the mounting member 16 will be described in detail. As shown in FIG.
It is fixed to the inside of the column 13 in the radial direction, and its tip portion projects toward the center. The tip of the tip is raised to form a mounting portion 16a. Therefore, the wafer W is mounted on the mounting portion 16a. In addition, this mounting portion 16
The distance a is set so as to support the inner portion of the wafer W between 40 mm and 50 mm, for example, preferably 44 mm. That is, L in FIG. 4 is set to 44 mm. As for the other mounting members 17 and 18, similarly to the mounting member 16, the mounting portion raised by one step at the tip thereof supports a portion 44 mm inside from the peripheral portion of the wafer W.

The mounting members 16, 17 and 18 are fixed at equal intervals in the vertical direction of the columns 13, 14 and 15, and the intervals are such that the wafer W to be mounted is mounted as shown in FIG. The pitch P is set to be 40 mm.

Regarding the mounting member for supporting the wafer W in this manner, as shown in FIG.
A ring-shaped support member 19 is fixed to the inside of the support members 14 and 15, and the mounting portions 19a and 19 are mounted on the upper surface of the support member 19.
b and 19c may be formed.

The ladder boat 10 constructed as described above
Is detachably mounted on a quartz heat insulating cylinder 21 having a flange portion 20 made of, for example, stainless steel via a support member 22, and the heat insulating cylinder 21 is mounted on a boat elevator 23 that can be raised and lowered. The wafer W is loaded on the ladder boat 10 in the reaction vessel 3 in the vertical furnace 2 by the boat elevator 23 being lifted up.

Next, the structure in the vertical furnace 2 for subjecting the wafer W as the object to be processed to the formation of a predetermined silicon oxide film will be described with reference to FIG. The casing 4 has its lower end fixed to the upper surface of the base plate 5 and is erected vertically. The casing 4 has a substantially cylindrical shape with a closed upper surface, the inner surface of which is covered with a heat insulating material 6, and the inner peripheral surface of the heat insulating material 6 has, for example, molybdenum disilicide (MoS).
The heating element 7 formed of a resistance heating element such as i ₂ ) is provided in a spiral shape, for example.

A soaking tube 8 made of, for example, SiC is arranged between the heating body 7 and the reaction vessel 3 so as to surround the reaction vessel 3. The heating body 7 is provided with an appropriate temperature control device ( (Not shown) is configured so that the inside of the reaction vessel 3 can be uniformly heated to and maintained at a predetermined temperature, for example, an arbitrary temperature between 600 ° C and 1100 ° C. There is. The temperature control device is configured so that the reaction container 3 can be divided into a plurality of zones in the vertical direction and finely adjusted for each zone.

The reaction vessel 3 having a processing region formed therein
Has a substantially tubular shape with an upper surface closed, and is erected in the vertical direction via a base plate (not shown) different from the base plate 5 via the flange portion 31 at the lower end. A gas discharge plate 33 located parallel to the top plate 32 of the reaction container 3 is provided in the upper portion of the reaction container 3, and the gas discharge plate 33 has a large number of discharge holes 3
4 are formed. Therefore, the space S surrounded by the gas discharge plate 33 and the top plate 32 and the like forms a kind of processing gas preliminary chamber, and the processing gas supplied into the space S is loaded into the reaction vessel 3. The wafer W is evenly ejected through the ejection holes 34.

A processing gas for forming a silicon oxide film, such as O ₂ (oxygen) gas, is introduced into the space above the reaction vessel 3 by a processing gas introduction pipe 41 rising along the outside of the reaction vessel 3. It is introduced into S, then discharged into the reaction container 3 through the discharge hole 34, and thereafter, is exhausted to the outside by an exhaust pipe 42 provided in the lower part of the reaction container 3.

The heat treatment apparatus 1 according to the present embodiment is constructed as described above. Next, the operation and the like will be described. First, the heating body 7 is caused to generate heat and the temperature in the reaction vessel 3 is
For example, while heating to about 600 ° C., N ₂ gas is introduced from the processing gas introducing pipe 41 to keep the inside of the reaction vessel 3 in an N ₂ gas atmosphere. Next, after mounting the wafer W which is the object to be processed on the ladder boat 10, the boat elevator 22 is raised, and as shown in FIG. 3, the flange portion 20 of the heat insulating cylinder 21 becomes the flange 31 of the lower end portion of the reaction container 3 and the flange portion 20. The ladder boat 10 is lifted to the position where the wafer W is closely attached and the wafer W is loaded into the reaction container 3.

Next, the inside of the reaction vessel 3 is heated to a predetermined processing temperature, for example, 1000 ° C., and the processing gas introducing pipe 4 is used.
When the O ₂ (oxygen) gas from 1 is introduced into the reaction container 3 and exhausted from the exhaust pipe 42, the inside of the reaction container 3 is maintained at a normal pressure, for example, and heat treatment is performed for a predetermined time as it is. A silicon oxide film (Si
O ₂ ) is formed.

By the way, in the case of raising the preheating temperature from 600 ° C. to the processing temperature of 1000 ° C., in order to improve the throughput and enhance the productivity utilizing the advantages of the batch processing, the temperature rising rate is set high. Should be done in. In this case, the wafer W having a diameter of 300 mm, which is an object to be processed,
Since it is considerably larger than a conventional wafer having a diameter of 200 mm, the difference in the amount of heat incident from the heating body 7 between the peripheral portion and the central portion becomes extremely large with the conventional mounting pitch. As a result, the in-plane temperature difference becomes large and slip occurs.

In this respect, since the mounting pitch of the ladder boat 10 used in this embodiment is set to 40 mm as described above, it is possible to reduce the in-plane temperature difference and prevent the occurrence of slip. Is.

The inventors of the present invention have actually verified by simulation and found that when raising the temperature from 600 ° C. to 1000 ° C. according to the present embodiment, the temperature was raised at a high rate of 100 ° C./min. The in-plane temperature difference of the wafer when passing through 950 ° C could be suppressed to 10 ° C. It is expected that slip will not occur with such a small in-plane temperature difference. To compare this point with the conventional one, when the mounting pitch is 10 mm and the temperature is raised at the same temperature rising rate,
The difference in in-plane temperature of the wafer after passing 950 ° C is 30
It reached to ° C. Therefore, it was confirmed that the present embodiment can suppress the in-plane temperature difference that causes the slip to be small even in the above-described high-speed temperature rising process.

Further, in comparison with the single wafer method, even in the case of short-time oxidation (10 minutes), even if the general throughput of the single wafer method is assumed to be 5 minutes / 1 sheet, in this embodiment It was confirmed that when eight wafers were mounted on the ladder boat 10, the productivity of this example was superior to that of the single wafer method. As a matter of course, in the case of long-time oxidation, the difference is further increased, and the productivity of this embodiment is much higher. Therefore, it is possible to heat-treat a large-diameter wafer of 300 mm with higher productivity than the single-wafer method and without causing slip.

Although the above-mentioned embodiment is an example in which the present invention is applied to the atmospheric pressure type heat treatment apparatus for performing the oxidation treatment and the diffusion treatment on the wafer, the present invention is applied to the reduced pressure type heat treatment apparatus, for example, the reduced pressure CVD apparatus. It can also be applied.

[0034]

According to the first, second, and third aspects, when heat-treating a wafer having a large diameter of 250 mm or more, slip is generated while adopting batch processing using a mounting jig for mounting a plurality of wafers. A heat treatment that does not occur is possible. In addition, as for the rate of temperature rise, no slippage occurs even if there is a temperature rise process of 20 ° C. per minute or more, so that the throughput is good and the productivity is better than that of the single wafer method.

[Brief description of drawings]

FIG. 1 is a graph showing changes in yield shear stress with changes in temperature of silicon.

FIG. 2 is a perspective view showing an overview of a heat treatment apparatus according to an embodiment of the present invention.

FIG. 3 is a cross-sectional explanatory diagram of a heat treatment apparatus according to an embodiment of the present invention.

4 is an enlarged side view of a mounting member of a ladder boat in the heat treatment apparatus of FIG.

FIG. 5 is a perspective view showing an outline of another mounting member usable for the ladder boat.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat treatment apparatus 2 Vertical furnace 3 Reaction vessel 7 Heating body 10 Ladder boat 13, 14, 15 Supports 16, 17, 18 Mounting member 41 Processing gas introduction pipe 42 Exhaust pipe W Wafer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomohisa Shimazu 1-24-141, Machiya, Shiroyama-cho, Tsukui-gun, Kanagawa Tokyo Electron Tohoku Co., Ltd. Sagami Business Office

Claims (3)

[Claims] 1. A mounting jig having a substantially tubular reaction container located in a tubular furnace, and a mounting jig for mounting a plurality of semiconductor wafers in parallel in a vertical direction, and mounting a plurality of semiconductor wafers. In a heat treatment apparatus configured to perform heat treatment on the semiconductor wafer in a predetermined temperature atmosphere in the reaction container.
0 mm or more, the predetermined temperature is 600 ° C or more 8
If the temperature is less than 00 ° C and the temperature is raised to the predetermined temperature atmosphere by the tubular furnace, 20 ° C per minute
A heat treatment apparatus configured to have the above temperature rising process, wherein the mounting pitch of the semiconductor wafer mounting jig is set to 10 to 40 mm. 2. A mounting jig having a substantially tubular reaction container located in a tubular furnace and a mounting jig for mounting a plurality of semiconductor wafers in parallel in a vertical direction, and mounting a plurality of semiconductor wafers. In a heat treatment apparatus configured to perform heat treatment on the semiconductor wafer in a predetermined temperature atmosphere in the reaction container.
Size of 0 mm or more, the predetermined temperature is 800 ° C or more 1
The semiconductor wafer mounting jig is configured to have a temperature raising process of 20 ° C. or more per minute during the temperature raising process of less than 000 ° C. until the temperature is raised to the predetermined temperature atmosphere by the tubular furnace. The heat treatment apparatus is characterized in that the mounting pitch in is set to 20 to 80 mm. 3. A mounting jig having a substantially tubular reaction container located in a tubular furnace and a mounting jig for mounting a plurality of semiconductor wafers in parallel in a vertical direction, and mounting a plurality of semiconductor wafers. In a heat treatment apparatus configured to perform heat treatment on the semiconductor wafer in a predetermined temperature atmosphere in the reaction container.
The size is 0 mm or more, the predetermined temperature is 1000 ° C. or more and less than 1100 ° C., and the temperature is raised to the predetermined temperature atmosphere by the tubular furnace, the temperature is increased to 20 minutes per minute.
The mounting pitch of the semiconductor wafer mounting jig is 30 to 160.
A heat treatment device characterized by being set to mm.