JPH07326593A - Method and device for heat treatment - Google Patents

Abstract

PURPOSE:To realize uniform in-plane temperature distribution of a heat treatment substrate simultaneously without lowering the number of heat treatment substrates to be treated at a time and without increasing a delay time. CONSTITUTION:The device is constituted of a heating chamber whereto specified gas is introduced, a heater which is installed in a periphery of the heating chamber and enables temperature rise and temperature lowering and a jig 30 for supporting a plurality of heat treatment substrates 12 arranged inside the heating chamber parallel mutually, and the jig 30 is positioned in a peripheral part of the thermal treatment substrate 12 and is provided with a reflection means 34 for reflecting radiant heat injected thereto or radiant heat emitted therefrom.

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 semiconductor wafers, glass substrates and the like.

[0002]

2. Description of the Related Art Conventionally, various heat treatment apparatuses have been used for forming a diffusion layer, a silicon oxide film, a silicon nitride film, etc. on a semiconductor wafer or a glass substrate. In these apparatuses, a predetermined heat treatment is generally performed by heating a substrate to be heat-treated contained in a reaction vessel (heating chamber) and introducing an inert gas or a reactive gas into the vessel.

The performance required as a heat treatment apparatus is (1) the resistance and depth of the diffusion layer to be formed, the silicon oxide film,
The film thickness of the silicon nitride film, etc. is uniform within the wafer surface and between wafers, and has high reproducibility. (2) The wafer should not slip or warp due to thermal strain due to temperature difference. (3) A large number of wafers can be processed per operation. (4) The processing time per operation is short. (5) Air is mixed in at the same time when the substrate to be heat treated is taken in and out of the container, and an oxide film does not grow on the surface of the substrate to be heat treated due to the air. Etc.

[0004] Conventionally, as compared with the semiconductor integrated circuit, 1000
In the process of heat treatment such as oxidation at a high temperature near ℃, a heat insulating material is provided around the heater to improve the temperature uniformity,
A soaking tube made of silicon carbide or the like is provided between the heater and the process tube. When performing high-temperature heat treatment using such a semiconductor heat treatment apparatus, air is simultaneously mixed when a semiconductor wafer is taken in and out of a container, an oxide film is formed in an uncontrolled atmosphere, and the oxide film is formed by high-temperature heat treatment. The uniformity of the film or the diffusion layer deteriorates, or the quality of the film deteriorates. To prevent these, lower the temperature when inserting the semiconductor wafer into the container, expel the mixed air with a high-purity gas such as nitrogen, argon, or oxygen, and then raise the temperature, and after the heat treatment, lower the temperature. The method of taking out is taken.

Therefore, if a heat treatment apparatus having a large heat capacity of a heat source is used, it takes time to raise and lower the temperature before and after the oxidation and heat treatment at a desired temperature, resulting in lower productivity.
There is a problem that the depth of the impurity diffusion layer cannot be kept shallow. In addition, if the semiconductor wafer is rapidly taken out from the container and then cooled after being subjected to oxidation or heat treatment, a large temperature difference occurs in the surface of the semiconductor wafer, causing slippage or warping and deformation. This is often due to a radial temperature difference in the plane of the semiconductor wafer.

In addition, when a plurality of substrates to be heat treated are installed vertically to the heater, if the heating rate of the heater is increased in order to raise the temperature rise, heating is radiated from the heater in principle. The heat is absorbed by the substrate to be treated, but because the multiple substrates to be treated that are placed in parallel with each other cast shadows on each other, the temperature difference around this substrate during heating and cooling becomes faster than at the center. It was difficult to make the radial temperature distribution of the substrate to be treated uniform.

As described above, conventionally, in order to heat a large number of semiconductor wafers once (batch type), it is desirable to install the wafers in the reaction vessel perpendicular to the heater and parallel to each other. When the temperature of the wafer is suddenly raised or lowered, or when loading / unloading (wafer loading / unloading) is performed, a temperature difference occurs in the radial direction of the wafer, and thermal distortion causes slipping, crystal defects, or warpage of the wafer. There was a problem such as occurrence of. Also,
Especially for 8-inch wafers or more, since a large temperature distribution is generated in the wafer surface, it is impossible to increase the temperature raising / lowering rate too much. Two solutions are proposed to solve this problem. There is.

One is to increase the distance between the wafers. When the distance between the wafers is increased, the non-uniformity in the wafer surface is slightly solved. However, this is not sufficient, and there is a problem that the number of wafers that can be processed at one time is significantly reduced.

The other is to use a "ring" as disclosed in JP-A-5-6894. That is, "when a plurality of substrates to be heat-treated are arranged in parallel to each other in a region surrounded by a heater, a jig for supporting the substrates is formed into a ring shape, and the heat capacity of the substrate including the jig is set at a central portion. The peripheral area is made larger than that of ". This is shown in FIG. Jig 1 for arranging semiconductor wafers 12 in parallel
A ring 17 having a relatively large heat capacity is connected to 3, and the heat capacity of the semiconductor wafer 12 including the jig 13 is set to be larger in the peripheral portion than in the central portion. As a result, in-plane non-uniformity of the wafer is significantly reduced. However, since the heat capacity of the peripheral portion of the wafer is set to be large, there arises a problem that the time (delay time) for the wafer temperature to follow the heater temperature at the time of raising and lowering the temperature increases. Therefore, the temperature raising / lowering rate cannot be increased sufficiently.

[0010]

As described above, the conventional heat treatment apparatus has a problem that the in-plane temperature distribution of the substrate to be heat treated becomes uneven when the temperature of the heater is raised or lowered. In the conventional solution for solving this problem, there are problems such as a decrease in the substrate to be heat-treated at one time and an increase in delay time.

The present invention eliminates the above-mentioned drawbacks, reduces the number of substrates to be heat treated at one time, does not increase the delay time, and at the same time makes the in-plane temperature distribution of the substrates to be heat treated uniform. It is an object of the present invention to provide a heat treatment device that enables the heat treatment.

[0012]

In order to achieve the above object, in the present invention, a heating chamber into which a predetermined gas is introduced, a heating heater installed around the heating chamber and capable of raising and lowering the temperature, And a jig for supporting a plurality of substrates to be heat-treated arranged in a heating chamber in parallel with each other.
An apparatus for heat treatment, comprising: a reflection unit that is located in the peripheral portion of a substrate to be heat treated and that reflects radiant heat incident on the substrate to be heat treated or radiant heat emitted from the substrate to be heat treated.

Further, this jig includes a ring-shaped member containing gold, platinum, silicon carbide or tungsten as a main component by quartz, and has a ring tray for supporting the peripheral portion of the substrate to be heat treated. It is characterized by doing.

Further, a step of arranging a plurality of reflecting means for reflecting the radiant heat incident on the heat-treated substrate or the radiant heat emitted from the heat-treated substrate on the peripheral portions of the plurality of heat-treated substrates, respectively, and And a step of raising or lowering the temperature of the heater arranged in the peripheral portion.

[0015]

When the means provided by the present invention is used, for example, when the temperature is raised, the radiant heat incident on the peripheral portion of the substrate to be heat-treated is reflected from the heater disposed in the peripheral portion of the substrate to be heat-treated,
Since this is irradiated to the central portion of the adjacent heat-treated substrate, the temperature increase in the peripheral portion of the heat-treated substrate is suppressed and the temperature increase in the central portion is accelerated. As a result, it is possible to raise the temperature at high speed while maintaining the uniformity of the processing temperature of the heat-treated substrate. On the contrary, when the temperature is lowered, the radiant heat radiated from the peripheral portion of the heat-treated substrate is reflected, so that it is possible to maintain the uniformity of the heat-treated temperature.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall structure of a heat treatment apparatus using the present invention. This heat treatment apparatus includes a vertical cylindrical outer tube 23 and an inner tube 24 that define a heating chamber 22 into which a predetermined gas is introduced,
A heater 21 installed around the heating chamber 22 and capable of raising and lowering the temperature, and a boat (a jig for supporting a plurality of semiconductor wafers (substrates to be heat treated) 12 arranged in the heating chamber 22 in parallel to each other. ) 32, a gas introduction pipe 28, and a gas discharge pipe 29.

Further, the boat 32 includes a ring-shaped member containing gold, platinum, silicon carbide, or tungsten as a main component with quartz, and a ring tray for supporting the peripheral portion of the semiconductor wafer 12. Equipped with 30. The ring-shaped member has a relatively high reflectance (0.
97 or more is preferable).

FIG. 2 is a perspective view showing the details of the boat 32. That is, the boat 32 includes four support rods 31,
The ring tray 30 is arranged in parallel with the ring tray 30. The ring tray 30 is composed of a ring-shaped reflection plate 34 that acts as a reflection means and an inclusion member 33 that includes the reflection plate 34. The inclusion member is made of the same member as the rod 31 or the like, for example, quartz or the like, which has a relatively small emissivity and absorptance with respect to heat radiation.

The specific dimensions of the ring tray 30 are shown in FIG.
This will be described with reference to (a). For 8-inch wafers, the ring has an inner radius of 60 to 80 mm and a width of 20.
It has a ring shape of -40 mm and a thickness of 2 mm. A gold reflector is included inside, and the specific dimensions of this reflector are 18 to 38 mm in width and 10 μm in thickness. The surface of the ring tray 30 and the reflection plate are separated by quartz of at least about 1 mm at any part. As a result, during the heat treatment, the semiconductor wafer
2 can be prevented from being contaminated. The distance between the semiconductor wafers 12 is 11 mm.

With this structure, when the temperature is raised, the radiant heat incident on the peripheral portion of the semiconductor wafer 12 is reflected from the heaters 21 arranged in the peripheral portion of the semiconductor wafer 12, and this is reflected. Since the central portion of the semiconductor wafer 12 is irradiated, the temperature rise in the peripheral portion of the semiconductor wafer 12 is suppressed and the temperature rise in the central portion is accelerated. As a result, it is possible to raise the temperature at high speed while maintaining the uniformity of the processing temperature of the semiconductor wafer. On the contrary, since the radiant heat radiated from the peripheral portion of the semiconductor wafer is reflected when the temperature is lowered, it becomes possible to maintain the uniformity of the temperature to be heat treated. Further, it becomes possible to set the wafer interval necessary to maintain the uniformity in the plane of the semiconductor wafer to be narrow.

FIG. 3 is a diagram comparing the characteristics of the present invention at the time of temperature rise with the conventional example. Reference numeral 55 is a set temperature of the heater 21, and shows how the temperature is raised from 600 ° C. to 1000 ° C. in 4 minutes. Reference numeral 511 indicates the temperature of the peripheral portion of the semiconductor wafer and 512 indicates the temperature of the central portion when a conventional boat (without a ring) is used. Reference numeral 521 indicates the temperature of the peripheral portion of the semiconductor wafer and 522 indicates the temperature of the central portion when a conventional boat (with a ring, the shape is optimized) is used. Reference numeral 501 indicates the temperature of the peripheral portion of the semiconductor wafer when the boat using the ring tray of the present invention is heated, and 502 indicates the temperature of the central portion. In both cases, the semiconductor wafer is heated from the peripheral portion, so that the peripheral portion has a higher temperature at any time. Reference numeral 51 is a temperature difference between the peripheral portion and the central portion at a certain time when the conventional boat (without the ring) is used. Reference numeral 52 is a temperature difference when using the conventional ring boat, and 50 is a temperature difference between the peripheral portion and the central portion when the ring boat of the present invention is used. From this figure, it is understood that when the boat with a ring is used, the temperature difference between the central portion and the peripheral portion is reduced and the uniformity is maintained. This is because the increase in heat capacity due to the conventional ring or the shielding effect due to the reflector of the present invention suppresses the temperature rise in the peripheral portion. Further, in the present invention, it can be seen that the follow-up time (delay time) of the substrate temperature with respect to the set temperature is significantly shortened as compared with the conventional ring. This is because in the conventional ring boat, the heat capacity of the peripheral portion of the semiconductor wafer is increased, so that there is a loss in the temperature rising time. However, in the ring of the present invention, the temperature difference is compensated by the reflector, so the heat capacity is reduced. Is almost never increased. Further, the radiant heat from the heater, which is reflected by the reflecting plate, is incident on the central portion of the semiconductor wafer, which also causes a rise in the temperature of the central portion of the wafer. As described above, the ring time of the present invention makes it possible to reduce the delay time while maintaining the temperature uniformity.

Although the above description has been made only when the temperature is raised,
The same applies to the case of cooling the temperature, and thus the description thereof will be omitted. Next, a modified example of the ring tray of the present invention will be described. FIG. 4B is a diagram showing specific dimensions of a modified example of the ring tray 30. The ring has an inner radius of 60-
It has a ring shape with a width of 80 mm and a width of 20 to 40 mm, a thickness of 2 mm, and a gold reflection plate is included inside. The specific dimensions of this reflection plate are a width of 18 to 38 mm and a thickness of 10 μm.
Is the same as the above-mentioned example. In this embodiment, a ring-shaped protrusion 35 having a height of 1 mm and a width of 1 mm is formed on the tray. Since the protrusion 35 supports the semiconductor wafer 12 at the center of the tray, it also contributes to uniform temperature. Similar to the example described above, the surface of the ring tray 30 and the reflection plate are separated by quartz of at least about 1 mm at any position. As a result, it is possible to prevent the semiconductor wafer 12 from being contaminated with gold or the like during the heat treatment.

FIG. 5 shows an example in which a disc tray 40 is used instead of the ring tray. According to FIG. 5A, in the disk-shaped tray 40, a portion of the disk-shaped tray 40 immediately below the peripheral portion of the semiconductor wafer has a ring-shaped reflector 44 having a thickness of 10 μm.
Are formed. This reflector is made of gold, platinum, tungsten or the like. The thickness of the tray is 2 mm. Further, a protrusion 45 is formed on the peripheral portion. Figure 5 (b)
Is a modification of the disc-shaped tray 40. That is, a ring-shaped reflector 44 having a thickness of 10 μm is formed inside the disc-shaped tray 40 immediately below the peripheral portion of the semiconductor wafer, and a disc-shaped reflector 44 is formed directly below the central portion of the semiconductor wafer. The radiation member 47 is formed. Radiant member 4
7 is made of a material such as silicon carbide or silicon, which has a higher emissivity and higher absorptivity than quartz in terms of heat radiation.
When the temperature is raised, the central portion of the semiconductor wafer is heated by the radiant heat from the radiant member, and when the temperature is lowered, the radiant member absorbs the heat in the central portion of the semiconductor wafer. As a result, the temperature can be raised and lowered at a higher speed than in the first embodiment of the present invention.

FIG. 6A shows a ring tray shown in FIG. 4B, which is provided with a lower protrusion 36 made of quartz or the like. Placing a semiconductor wafer on this tray adds substantial heat capacity to the periphery of the wafer,
By adjusting the height of the protrusions and the like, it is possible to further increase the uniformity of temperature during temperature increase and decrease. Figure 6
FIG. 5B shows a lower projection 36 added to FIG. Similarly, it is possible to further increase the uniformity of temperature during temperature increase and decrease.

[0025]

As described above, according to the present invention, the number of substrates to be heat-treated at one time does not decrease, the delay time does not increase, and at the same time, the in-plane temperature distribution of the substrates to be heat-treated is made uniform. It is possible to provide a heat treatment apparatus capable of performing the above.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing details of the boat according to the embodiment of the present invention.

FIG. 3 is a diagram showing temperature characteristics during temperature rise of the present invention and a conventional example.

FIG. 4 is a cross-sectional view showing details of the tray in the embodiment of the present invention.

FIG. 5 is a sectional view showing details of a tray according to another embodiment of the present invention.

FIG. 6 is a sectional view showing details of a tray according to still another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a conventional example.

[Explanation of symbols] 30 ring tray 31 support rod 32 boat 33 inclusion member (quartz) 34 reflector (gold)

Claims (3)

[Claims] 1. A heating chamber into which a predetermined gas is introduced, a heater installed around the heating chamber and capable of raising and lowering the temperature, and a plurality of substrates to be heat-treated arranged in the heating chamber are mutually connected. The jig is configured to support in parallel, and the jig is provided in the peripheral portion of the heat-treated substrate and has a reflection means for reflecting radiant heat incident on the heat-treated substrate or radiant heat emitted from the heat-treated substrate. A heat treatment apparatus comprising. 2. The jig includes a ring-shaped member containing quartz, a ring-shaped member containing gold, platinum, silicon carbide, or tungsten as a main component, and a tray for supporting a peripheral portion of the substrate to be heat-treated. The heat treatment apparatus according to claim 1, wherein 3. A step of arranging a plurality of reflecting means for reflecting radiant heat incident on the heat-treated base body or radiant heat radiated from the heat-treated base body on the peripheral portions of the plurality of heat-treated base bodies, respectively. And a step of raising or lowering the temperature of a heater arranged in the peripheral portion of the base body.