JPH03185818A - Heat treatment method and equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to heat treatment technology, particularly g1 in heat treatment equipment.
＠It relates to cooling technology, and is effective for use in the diffusion treatment of dull materials in, for example, the molding process of semiconductor iIN.

[Conventional technology]

In the manufacturing process of semiconductor devices, a method of depositing, stretching and diffusing impurities on semiconductor wafers is performed by applying lI! to multiple wafers. After carrying the placed boat into the process tube at a relatively low temperature (e.g. 800 to 900°C), the furnace temperature is raised to a predetermined temperature (e.g. cL 1000 to 1200"C) and processing is carried out for a predetermined time, and then There is a method called a so-called furnace-heat-furnace-cool process, in which the furnace temperature is lowered to a low temperature and then a boat on which wafers are mounted is taken out from a process tube.

An example of such a furnace heating/furnace cooling process is disclosed in Japanese Patent Application Laid-Open No. 58-33083.

A diffusion device used in such a furnace heating/furnace cooling process consists of a heating heater, a heat insulating material to which the heater is fixed, a process tube, and a soaking tube (
S i C) etc. have a large heat capacity (, the rate of temperature reduction (furnace cooling) in the furnace heating and furnace cooling process is low, especially at relatively low temperatures (below 1000°C), and therefore,
Processing cycle time becomes longer, and work efficiency and furnace efficiency become lower.

Further, in a relatively short-time process (for example, 20 minutes or less), it is difficult to apply the furnace-heat-furnace-cool process itself.

If the wafer diameter is further increased, wafer deformation, cracking, thermal stress dislocation, etc. are likely to occur, so the low temperature in the furnace-heating and furnace-cooling process method is further lowered (for example, from 900°C to 800°C). ), and as the process tube becomes larger, its heat capacity also increases, making the problem even more serious.

Therefore, as described in Japanese Patent Application Laid-Open No. 58-33083, a cooling fluid is introduced into the space between the heater and the heat insulating material as a technique to increase the rate of temperature reduction in the furnace cooling process. A technology has been proposed in which a blowing pipe is inserted in the axial direction, and the blowing pipe allows cooling fluid to flow through the space between the heater and the heat insulating material, thereby forcibly cooling the process tube. There is.

In addition to this, an example of technology for forcibly cooling a process tube is disclosed in Japanese Utility Model Application Publication No. 53-9870.
Publication No. 1, Publication No. 131282 of 1982, Publication of Utility Model Application No. 54-131282, Publication No. 1982
Publication No. 7-54122, Publication of Japanese Utility Model Application No. 55-14791, Publication No. 49500 of Utility Model Publication No. 1987, Publication of Japanese Utility Model Application No. 58-158
There is public mold No. 442.

[Invention tries to solve! 1111 However, in the heat treatment apparatus described in JP-A-58-33083, the space between the heater and the heat insulating material is cooled, so the cooling rate is low, and the cooling rate is low, and the heat treatment only occurs near the outlet of the blow pipe. The inventors have revealed that there is a point B where the temperature variation within the process tube increases because the process tube is locally cooled.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat treatment apparatus that can increase the rate of temperature drop in a furnace-heat-furnace-cool process while preventing variations in temperature within a process tube.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

An overview of typical inventions disclosed in this application is as follows.

That is, the heat treatment includes a process tube including a processing chamber into which a group of semiconductor wafers is carried in and out, and a heater that is mounted on the process tube and heats the inside of the processing chamber with or without a soaking tube. In the device,
A flow path is provided inside at least one wall of the process tube, the soaking tube, and the jig carried into the processing chamber, and a cooling fluid is allowed to flow through the flow path. It is characterized by being configured.

[Effect]

According to the above-mentioned means, in the furnace cooling process, the cooling fluid is caused to flow through the flow passages established in the process tube, soaking tube, and jig at the same time as the furnace cooling starts, thereby directly cooling the process tube, etc. Since forced cooling can be performed, the rate of temperature drop can be increased, and as a result, the time required for the entire process can be shortened.

At this time, the cooling fluid is passed through the entire length of the process tube, soaking tube, or jig.
Cooling will be uniform and the cooling effect will be carried out very efficiently.

〔Example〕

Fig. 1 is a cross-sectional view of a diffusion device according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view taken along line T in Fig. 1, and Fig. 3 is an exploded view showing the flow path. 4rA is a diagram showing the sequence of the furnace heating and cooling process; FIG. 5 is a vertical cross-sectional view showing the wafer loading process; FIG. 6 is a partial cross-sectional view for explaining the operation; FIG. FIG. 8 is a vertical cross-sectional view showing a heat treatment process, and FIG.

In this embodiment, a diffusion device as a heat treatment device according to the present invention is equipped with a process tube 1 formed in a substantially cylindrical shape using quartz glass or the like, and this process tube 1 includes a furnace opening 1a and a process gas. Supply Btb is arranged and opened at both ends, and a processing chamber 2 is substantially formed in the hollow part of the cylinder. A heater 3 is disposed outside the process tube 1 so as to surround it, and the heater 3 uniformly heats the process chamber 2 through a soaking tube 6 and a process tube 1, which will be described later. There is. The heater 3 is constructed by winding a heater element 114 into a cylindrical coil having a predetermined pitch, and the heater element 114 is comprised of an electric resistor that generates heat when energized.

The outside of the heater 3 is covered with a heat insulating material 5 made of quartz wool or the like, and the heater 3 is supported by this heat insulating material 5.

A soaking tube 6 made of silicon carbide (S i C) or the like and formed into a cylindrical shape with a larger diameter than the process tube l is disposed outside the process tube l between it and the heater 3. , a process tube 1 is placed on the inner bottom surface of the hollow part of this soaking tube 6! Further, the soaking tube 6 is placed on the inner bottom surface of the hollow portion of the heater 3.

A pair of guide rails 11% 12 are disposed at the inner bottom of the processing chamber 2 of the process tube l so as to extend in the axial direction at mutually symmetrical positions spaced apart in the circumferential direction.
An upstream flow &W13 and a downstream flow 'll114 are respectively established in the axial direction from the processing gas supply path 1b side of the process tube 1 inside both guide rails 11.12.

Upstream distribution! An air supply pipe 15 is connected to s13,
A blower 1117 is connected to the air supply pipe 15 as an air supply source for supplying air 16 as a cooling fluid. On the other hand, an exhaust pipe 18 is connected to the downstream flow path 14, and a cooling bag 219 for cooling the air 16 is connected to the exhaust pipe 18.

Also, is there a connecting hole 20 on both guide rails 11% 12? 3. ISi are arranged in a row at a predetermined pitch in the axial direction so that the upper surfaces of both guide rails communicate with the flow passages 13 and 14, respectively. Furthermore, a pair of stop flange 21.21 is provided on the processing gas supply path on both guide rails 11.12] bf11@.
are protruding from each.

A cooling jig 22 is slidably installed between the tops of both idle rails 1112, and this jig 22 is made of quartz glass or the like, and has a cross-sectional shape that is approximately s mist-shaped. It is formed so that it can surround a group of wafers, which will be described later. 20 There is an intermediate flow passage 2 inside the wall of the jig 22.
3 are arranged parallel to each other at a predetermined pitch in the center direction, and are each opened in an S-hoof shape, and both ends of each intermediate flow passage 230 are opened at both lower surfaces of the jig 22. A pair of communication ports 24.
24 respectively. This communication hole 24 is the communication hole 2 of the guide rail 13.14.
The intermediate road 23 group is aligned and opened on the jig 22 so as to match the 0 group.

The cooling jig 22 configured in this way is
From the furnace opening 1a of the process tube 1 to the guide rail 11.
12 and pushed into the processing gas supply path 1bll, and carried into the processing chamber 2 of the process tube 1. Jig 2
2 is positioned when its real end abuts against the stopper 21, 21 on the guide rails 11, 12. In this state, each communication port 2 of the intermediate flow road 23 in the jig 22
Since the 4 groups are aligned with the guide rails 11 and 120 communication holes 20M#, the upstream communication path 13 and the intermediate communication path 2
3 and the downstream communication path 14 are fluidly connected, and thereby substantially constitute a communication path 25 that spans the process tube 1 and the jig 22.

Next, the action will be explained.

When performing diffusion processing on wafers 7 as objects to be processed, a boat 8 on which a plurality of wafers 7 are erected is carried into the process tube 1 from the furnace mouth 1a to approximately the center, and the sequence for the furnace heating furnace cooling process @Il ffi is carried out. (not shown), the processing is executed in a processing sequence as shown in FIG.

That is, the wafers 7 and the boat 8 are carried in through the furnace opening 1a of the process tube 1 when the temperature is low.

At this time, as shown in FIG. 5, the boat 8 on which a plurality of wafers 7 are placed is placed in the center of the cooling jig 22. In this state, the wafers 7 and the boat 8 are carried into the processing chamber 2 together with the cooling jig 22.

When the wafers 7 and the boat 8 are carried into the processing chamber 2 from the furnace mouth 1a while being covered by the cooling jig 22, the process tube 1 is heated by the radiant heat from the heater 3.
1 heat or the entire cooling jig 22 is heated through this heat. Then, after the cooling jig 22 is heated entirely and uniformly, the entire wafer 7 and boat 8 are heated uniformly.

Here, when the group of wafers 7 and the boat 8 are carried into the process tube 1, a temperature difference occurs between the group of wafers 7 in the front region of the boat 8 in the advancing direction and the wafers 18 in the rear region wi. In order to prevent this, the boat 8 is gradually moved at a gentle speed. Furthermore, for the same reason, the heating temperature of the process tube l by the heater 3 at the time of delivery is temporarily lowered below the predetermined processing temperature.For example, the processing temperature is approximately 1200°C.
In this case, the temperature will drop to about 800°C during loading and unloading.

In this way, during loading, the heating temperature by the heater 3 is lowered and the boat 8 is gradually moved, thereby suppressing the occurrence of a temperature difference between the front and rear of the group of wafers 7 on the boat B. Ru. As a result, the difference in heat treatment rate (degree) within the 7 groups of wafers (within 1 batch) on boat B is tfII@.

By the way, in the case of the conventional example in which the wafer 7# and the boat 8 holding it are carried into the process tube 1 without being surrounded by the cooling jig 22, as shown in FIG. ] The radiant heat is applied to the group of wafers 7 obliquely from the front, and a thermal shadow (see the shaded area in Fig. 6) is formed by the adjacent wafer within the wafer 7. However, there is a problem in that dislocation defects and wafer deformation occur due to thermal stress at the periphery, middle, and center of the wafer.

However, in this embodiment, the group of wafers 7 and the boat 8 holding them are carried in while being surrounded by the cooling jig 22, so the radiant heat of the process tube l casts a shadow on the wafers 7. does not occur.

That is, the group of wafers 7 and the boat 8 are placed in the cooling jig 22.
When the process tube 1, surrounded by First, the cooling jig 22 is heated by the radiant heat of the tube 1 . Therefore, the group of wafers 7 surrounded by the cooling jig 22 are blocked from the radiant heat from diagonally in front of the process tube 1, so a thermal shadow is generated inside the wafers 7 due to the radiant heat irradiated from diagonally in front. It is possible to avoid this.

Then, while the group of wafers 7 and the boat B are being gradually carried into the process tube l at a slow speed while being surrounded by the cooling jig 22, the cooling jig 22
is heated entirely and uniformly by the radiant heat of the process tube l. At this time, since the cooling jig 22 is set to thick, the local temperature difference that occurs due to the difference in heating time between the front and rear parts of the cooling jig 22 is suppressed, and the cooling jig 22 is heated as a whole. The temperature distribution becomes approximately uniform.

In this way, when the cooling jig 22 is heated entirely and uniformly, the wafers 7 group and the boat 8 are heated to the cooling jig 22.
2 and the radiant heat of the process tube I through the cooling jig 22. At this time, since the radiant heat is irradiated to the group of wafers 7 in the radial direction from the outer periphery thereof, no thermal shadow is generated between the adjacent wafers 7.

Therefore, there is no temperature difference between the periphery and the center of the wafer 7, and the temperature distribution is uniform, suppressing the generation of thermal stress due to the temperature difference.As a result, dislocation defects and wafer damage due to thermal stress are suppressed. This will prevent deformation from occurring.

When the boat 8 holding the 7 groups of wafers is carried into the processing chamber 2 of the process tube L, the cooling jig 22 is pulled out from the furnace opening 1a of the process tube L, as shown in FIG. As shown in the figure, the furnace opening Ia is closed by the cap 26, and the furnace temperature is heated by the heater 3 to increase the temperature at 8°C/min. Along with
A predetermined processing gas is supplied from the processing gas supply port tb, and heat treatment is performed under predetermined processing conditions.

After the prescribed processing is completed, the furnace cooling step begins, but during this time -
The cooling jig 22 that has been carried out is again carried into the processing chamber 2 of the process tube 1, which is at a high temperature, so that the processing chamber 2 of the process tube 1 is forcibly cooled.

That is, when the cap 26 is removed from the furnace mouth 1a, the cooling jig 22 is placed between the guide rails 12 and the process tube 1 is removed, as shown in FIG.
The cooling jig 22 is carried into the back of the processing chamber 2 from the furnace opening 1a until the end of the wafer 11J hits the stopper 21. When the end of the back end 11J hits the stopper 21, the cooling jig 22 cools the wafer 7 on the boat 8. The group is surrounded, and as described above, the communication port 24 of each intermediate flow passage 23 is connected to the upstream flow 813 and the downstream flow! 14 communication holes 20 .

When the cooling jig 22 is carried into the processing chamber 2, since the cooling jig 22 has a large heat capacity, the heat of the processing chamber 2 is taken away by the cooling jig 22, and the processing chamber 2 is heated. It will be forced to cool down. Therefore, forced cooling is started at the same time as entering the furnace cooling step.

Next, the cooling jig 22 is stopped at a predetermined position, and at the same time, as shown in FIG. The air 16 as a fluid for use flows through the air supply pipe 15 → upstream passage 13 → communication hole 20 → intermediate flow passage 2.
3→communication hole 20→downstream distribution 1314→exhaust pipe 18→cooling device N19. The process tube 1 is forcibly cooled by the air 16 to a low temperature (for example, 800° C.).

By the way, when forced cooling is not performed, the cooling rate is 2-b and the furnace cooling time is 67-100 minutes. According to this example, the cooling rate is 5-b and the furnace cooling time is 20-40 minutes. It can be shortened to minutes.

The cooling rate can be freely set by the amount of air supplied from the blower based on the control by the sequence control device for the furnace cooling process.

In order to prevent thermal stress dislocation, the method in which the processing sequence is at a constant high temperature, that is, the method in which the boat 8 holding the wafer 7 R'll at high temperature is carried in and carried out, is changed to the processing sequence shown in FIG. 4. However, if the original processing conditions are relatively short-time processing (for example, processing at 1000°C for 5 to 20 minutes), when the cooling rate is slow as in the conventional case,
Since the heat treatment progresses in this furnace cooling step, the high temperature step shown in FIG. 4 cannot be taken sufficiently, making it difficult to set the furnace heating furnace cooling treatment sequence. This makes it possible to set the furnace heating and furnace cooling treatment sequences.

Here, the air 16 as a cooling fluid is directly sent and circulated in the processing chamber 2 of the process tube 1 through the communication path 25 extending between the process tube 1 and the cooling jig 22, so that the air 16 is circulated. The cooling effect of the air 16 is extremely high, and the temperature decrease rate is extremely fast.

Note that if the low temperature at the start of the process (e.g., 800°C) and the low temperature at the end of the process (e.g., 940°C) are different,
It is necessary to lower the temperature further before the next treatment, but
According to this embodiment, this preparation time can also be shortened.

In this way, when the processing chamber 2 of the process tube 1 is cooled to a predetermined low temperature (800° C.), the group of 7 wafers held in the boat 8 are together covered with the cooling jig 1422. It is transported from the processing chamber 2 to the furnace opening 1a.

When the 7 groups of wafers are carried out from the furnace opening 1a of the processing chamber 2 while being covered by the cooling jig 22, the wafers are removed after the cooling jig 22 has been completely and uniformly cooled. Group 7 is completely cooled. Also, during this export,
The 7 groups of wafers are surrounded by the cold W jig 22,
Since the wafer 7 moves through the furnace opening 1a, no thermal shadow is generated on the wafer 7 due to the radiant heat of the process tube 1. Therefore, as in the case of loading, no temperature difference occurs between the group of wafers 7 and within the wafer 7, the temperature distribution becomes uniform, and the generation of thermal stress due to the temperature difference is suppressed.
This will prevent dislocation defects and wafer deformation due to thermal stress.

According to the embodiment described above, the following effects can be obtained.

(1) By opening a cooling fluid flow path inside the wall of the process tube and the cooling jig and supplying the cooling fluid to this cooling fluid flow path, the cooling fluid is delivered to the processing chamber of the process tube. Since it can be supplied directly, the processing chamber of the process tube can be forced and directly cooled, and as a result, the temperature drop rate of the processing chamber of the process tube can be increased, reducing the processing time. The required time can be reduced.

C) By forming the cooling fluid flow path in the cooling jig, the cooling fluid can be appropriately supplied to a desired location, so the effect of (1) above can be further enhanced.

(3) By placing a cooling jig with a large heat capacity in the processing chamber of the process tube, the heat in the processing chamber of the process tube can be absorbed by the cooling jig.
The processing chamber of the process tube can be forcedly cooled very easily.

(4) Carrying in and out of the process tube with the wafer group surrounded by a cooling jig;
The cooling jig can block the diagonal radiant heat from the process tube on the group of wafers, suppressing the generation of thermal shadows between adjacent wafers and heating the wafers evenly from the radial direction. As a result, it is possible to prevent a temperature difference between the periphery and the center of the wafer.

(5) By making the temperature distribution within the wafer uniform, it is possible to suppress the generation of thermal stress, thereby preventing the occurrence of dislocation defects and wafer deformation due to the generation of excessive thermal stress. , the heat treatment rate can be made uniform throughout the wafer.

(ω By preventing the occurrence of wafer defects such as thermal stress dislocation defects and deformation of the wafer, and by making the heat treatment rate uniform throughout the wafer, it is possible to improve the product yield and the quality and reliability of the product. can.

(7) By avoiding uneven temperature distribution within the wafer due to oblique radiant heat irradiation from the process tube to the wafer group when loading and unloading the wafer group into and out of the process tube, the wafer group can be gradually advanced during loading and unloading. Therefore, it is possible to suppress the occurrence of a temperature difference between the front and the rear in the traveling direction of the wafer group, and as a result, it is possible to uniformize the heat treatment rate as a whole within the wafer group (within one buffet).

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, cooling fluid flow passages are not limited to those disposed in process tubes and cooling jigs;
Like the flow path 25A shown in Figure 0, the soaking tube 6A
It may be arranged in a spiral shape inside the wall.

Further, the cooling fluid flow path may be arranged inside the wall of the process tube, and can also be applied to heat treatment am without a soaking tube.

As the cooling fluid, not only air but also nitrogen gas etc. can be used, and Ii! may be configured for use.

Furthermore, the forced cooling of the processing chamber of the process tube is not limited to a configuration in which cooling fluid is circulated, but the cooling jig is carried into the processing chamber of the process tube. The heat capacity of the jig may be used to forcibly cool the process tube by absorbing heat in the processing chamber. In this case, the cooling jig section shown in FIG. 11 and FIG. Cooling jigs 22A and 22B may be configured to have a large heat capacity, and the cooling jigs may be taken in and out of the process tube processing chamber many times (the old and new ones may be replaced and taken in and out). You may also do so.

In the above explanation, the invention made by the present inventor was mainly applied to a diffusion device, which is the background field of application. It can be applied to general heat treatment equipment.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

By creating a cooling fluid flow path inside the walls of the process tube, cooling jig, and soaking tube, and by flowing the cooling fluid through the cooling fluid flow path, the process tube is forcibly moved by the cooling fluid. Since the process tube can be directly cooled, the temperature drop rate of the process tube can be increased, and the time required for processing can be shortened.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing a diffusion device which is an embodiment of the present invention, FIG. 2 is a partially omitted enlarged sectional view taken along line G in FIG. 1, and 3 &! 1 is an exploded perspective view showing the cooling fluid flow passage, FIG. 4 is a diagram showing the sequence of the furnace cooling process, FIG. FIG. 7 is a vertical cross-sectional view showing the heat treatment process, and FIG. 8 is a vertical cross-sectional view showing the cooling jig loading process for explaining the operation. Figure 9 shows a heat treatment apparatus which is another embodiment of the present invention.
IWi side view, FIG. 10 is a partial perspective view of the soaking tube showing the cooling fluid flow passage. FIG. 11 is a perspective view showing a cooling jig used in another embodiment of the present invention, and FIG. 12 is a perspective view showing the same (another cooling jig) l...process tube; 2-...processing room, 3...
Heater, 4... Heater wire, 5... Insulating material, 6.6
A-... soaking tube, 7... wafer (workpiece), 8...
... Boat (processing jig), 11.12... Guide rail, 13... Upstream flow path, 14...-Downstream flow path, 15... Air supply pipe, 16... Air (cooling) fluid),
17--Feeding 1R11, 18--Exhaust pipe, 19-Cooling i
t, 20-... Communication hole, 21... Stopper, 22.2
2A, 22B--Cooling treatment area 23--Intermediate flow passage,
24-...Connection port, 25.25A...Cooling fluid flow path, 26-...Cap.

Claims (1)

[Claims] 1. A group of semiconductor wafers is carried into a processing chamber of a process tube, the group of semiconductor wafers is heated by a heater mounted on the process tube, and after heat treatment, the group of semiconductor wafers is carried out from the processing chamber of a process tube. A heat treatment method characterized in that the process tube is forcibly cooled by carrying a cooling jig into the process chamber for the process tube. 2. A process tube equipped with a processing chamber into which a group of semiconductor wafers is carried in and carried out;
A heat treatment apparatus comprising a heater that heats the inside of the processing chamber with or without a heat soaking tube, the process tube, the heat soaking tube, and a jig carried into the processing chamber. A heat treatment apparatus characterized in that a flow passage is provided inside at least one wall body, and the cooling fluid is configured to flow through the flow passage. 3. The flow path is formed inside the wall of the process tube and inside the wall of the jig carried into the process tube processing chamber so as to surround the group of semiconductor wafers, and the cooling fluid 3. The heat treatment apparatus according to claim 2, wherein the heat treatment apparatus is configured to flow through the flow path of the process tube to the flow path of the jig. 4. The heat treatment apparatus according to claim 2, wherein the flow passage is arranged in an annular shape inside the wall of the soaking tube.