JP2015005652A - Thermal treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal treatment technology which conducts high temperature thermal treatment to a heated body having a large diameter in a clean atmosphere.SOLUTION: A thermal treatment device of the invention includes: a device body 2; a reaction tube 3 into which a reaction gas may be introduced, the reaction tube 3 which is formed into an elongated shape in the device body 2, houses a planar heated body 21, and has light permeability; and light radiation heating means disposed at a position in the device body 2 which is located outside the reaction tube 3 and including lamps which radiates light to the heated body 21 to heat the heated body 21. The reaction tube 3 is made of quartz, and a longitudinal cross sectional shape of the reaction tube 3 is formed into an elliptical shape.

Description

  The present invention relates to a heat treatment technique such as thermal oxidation of a silicon carbide substrate.

Conventionally, as this type of heat treatment apparatus, an apparatus for heating an object to be heated by light irradiation using a lamp is known.
In general, in a heat treatment apparatus using light irradiation, the distance between a lamp and an object to be heated greatly affects the heating efficiency, and the efficiency decreases as the distance increases.

  In the case of conventional light irradiation type heat treatment equipment, a quartz tube having a perfect cross-sectional shape is used as a reaction furnace, so the distance between the lamp and the object to be heated increases as the diameter of the object to be heated increases, and the heating efficiency There is a problem that the remarkably decreases. For this reason, it has been difficult to heat-treat a large-diameter semiconductor substrate at a high temperature of 1200 ° C. or higher in a reaction tube.

  Further, as this type of heat treatment apparatus, one that heats by a hot wall furnace (diffusion furnace) is also known. However, in such a conventional technique, the reaction tube itself is heated to generate impurity gas, so that light transmission is performed. There is a problem that regular use at 1200 ° C. or higher using a reaction tube is difficult.

  In recent years, silicon carbide (SiC), which has been attracting attention as a next-generation power semiconductor material, is expected to be used in MOS power devices because it can form a thermal oxide film. Therefore, a technique for performing heat treatment on a silicon carbide substrate at a high temperature is demanded.

JP 2009-231341 A JP 2010-27757 A

  The present invention has been made in view of the above-described problems of the conventional technology, and an object of the present invention is to provide a heat treatment technology capable of heat-treating a heated object having a large diameter at a high temperature in a clean atmosphere. There is.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. An apparatus main body, and a light-transmitting reaction tube which is formed in an elongated shape capable of introducing a reaction gas in the apparatus main body and accommodates a flat body to be heated. And a light irradiation heating means disposed outside the reaction tube in the apparatus main body and having a lamp for irradiating and heating the object to be heated, the reaction tube having a longitudinal direction thereof Is a heat treatment apparatus in which the cross-sectional shape is formed in an oval shape.
In the present invention, the light irradiation heating means has a plurality of rod-shaped lamps extending in the longitudinal direction of the reaction tube, and among the plurality of lamps, the upper side and the lower side of the heated body so as to sandwich the heated body. It is also effective when the upper lamp group and the lower lamp group, which are arranged on the side and are composed of a plurality of lamps, are arranged at positions where the lamps do not overlap in the vertical direction.
The present invention is also effective when a susceptor for supporting the object to be heated is provided and at least a surface layer portion of the susceptor is made of a silicon carbide light absorber.
The present invention is also effective when the reaction tube is made of quartz.
The present invention is also effective when a gas detector for detecting residual gas in the reaction tube is provided.
The present invention is also effective when the reaction tube and the light irradiation heating means have cooling means for cooling with a cooling medium.

According to the present invention, for example, by making the longitudinal cross-sectional shape of an elongated reaction tube made of quartz into an oval shape, even when the object to be heated is large, it is directed toward the long axis direction of the reaction tube. The distance between the lamp of the heating means and the heated body can be kept shorter than that of the prior art with respect to the placed heated body, thereby reducing the heating efficiency when heating the heated body having a large diameter. Therefore, high temperature heat treatment can be performed on the object to be heated.
According to the present invention, since the reaction tube is not directly heated, the generation of impurity gas can be extremely reduced, whereby heat treatment can be performed in a clean atmosphere.

  On the other hand, in the case of so-called cold wall type lamp heating, it is difficult to maintain in-plane temperature uniformity at a high temperature as compared with a normal hot wall furnace. Among them, an upper lamp group and a lower lamp group made up of a plurality of lamps arranged above and below the heated body so as to sandwich the heated body are arranged at positions where the lamps do not overlap in the vertical direction. In this case, since the light to be heated can be uniformly irradiated to the object to be heated, the in-plane uniformity of the temperature of the object to be heated can be maintained.

  Further, in the present invention, when at least the surface layer portion of the susceptor for supporting the object to be heated is made of a silicon carbide light absorber, the object to be heated that is difficult to be directly heated by light irradiation is also interposed through the susceptor. It is possible to perform heat treatment by heating.

  Furthermore, in the present invention, when a gas detector for detecting the residual gas in the reaction tube is provided, the heat treatment is always performed in a clean atmosphere by exhausting based on the result obtained by the gas detector. It becomes possible to do.

  In addition, in the present invention, when the cooling means for cooling the reaction tube and the heating lamp with a cooling medium is provided, the temperature of the reaction tube can be kept low, so that quartz that could not be conventionally used as a material for the reaction tube is used. Can be used.

Schematic which shows the whole structure of the heat processing apparatus of embodiment of this invention Sectional view showing the internal configuration of the heat treatment apparatus Explanatory drawing showing the reaction tube of the heat treatment equipment Explanatory drawing which shows arrangement | positioning of the upper side lamp group and the lower side lamp group in the heat processing apparatus

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the overall configuration of the heat treatment apparatus of the present embodiment.
As shown in FIG. 1, the heat treatment apparatus 1 according to the present embodiment is of a so-called cold wall type, and is configured by providing a light-transmissive reaction tube 3 in an apparatus main body 2 made of, for example, a metal material. Yes.

The apparatus main body 2 and the reaction tube 3 of the present embodiment are each formed in an elongated shape, and the longitudinal direction (X-axis direction in the figure) is directed in the horizontal direction. The reaction tube 3 is arranged and configured so as to penetrate the apparatus main body 2.
A heating unit 4 having a plurality of lamps is provided around the reaction tube 3 in the apparatus main body 2 as described later.

On the other hand, for example, an upper portion of the apparatus main body 2 is provided with gas introduction means 5 for introducing a cooling medium (for example, air) made of, for example, gas, and for example, a lower portion of the apparatus main body 2 is used to discharge the cooling medium. The gas discharge means 6 is provided.
The gas introduction means 5 and the gas discharge means 6 constitute a cooling means 7 for circulating the inside of the apparatus main body 2 with a cooling medium to cool the reaction tube 3 and the heating means 4.

A gas supply source 8 for introducing a reaction gas is provided at one end of the reaction tube 3.
A susceptor 20 supported by a support member 23 is provided in the reaction tube 3, and a heated object 21 such as a silicon carbide substrate is supported on the susceptor 20. The support member 23 supports the susceptor 20 via, for example, a pin-shaped member 24.
Further, a gas detector 22 for detecting the concentration of residual gas such as impurity gas is provided at the rear stage of the gas discharge valve 9 at the other end of the reaction tube 3.

FIG. 2 is a cross-sectional view showing the internal configuration of the heat treatment apparatus of the present embodiment, and FIG. 3 is an explanatory view showing a reaction tube of the heat treatment apparatus.
In the present invention, the cross-sectional shape in the longitudinal direction of the reaction tube 3 is formed in an oval shape.

In the present invention, the “oval shape” has two focal points in addition to the shape having the arc surface portions 32 and 33 at both ends of the opposing horizontal surface portions 30 and 31 as in the embodiment shown in FIG. An elliptical shape is also included.
On the other hand, in the case of the present invention, the material of the reaction tube 3 is not particularly limited, but from the viewpoint of high light transmittance for light in the infrared region and easy availability of a high-purity quartz tube, It is preferable to use what consists of.

As shown in FIG. 2, for example, a flat plate-shaped susceptor 20 is provided in the reaction tube 3 in a horizontal direction that is the major axis direction of the reaction tube 3.
On the susceptor 20, the heated object 21 is supported in the horizontal direction, which is the long axis direction of the reaction tube 3. In this case, the heated body 21 is configured to be disposed in the central portion of the reaction tube 3.

  In the case of the present invention, the material of the susceptor 20 is not particularly limited, but at least the surface layer portion is made of silicon carbide from the viewpoint of enabling heating of the heated object 21 that is difficult to heat by light irradiation. It is preferable to use a light absorber. The susceptor 20 and the heated object 21 are preferably in surface contact.

  Such a susceptor 20 itself is made of a silicon carbide high-purity single crystal, polycrystal or crystalline light absorber, and is made of such a light absorber on the surface of a flat plate member made of carbon. What formed the film can also be used.

On the other hand, the heating means 4 of the present embodiment has a plurality of lamps provided in the vicinity of the periphery of the reaction tube 3.
The lamps of the heating means 4 are each formed in the shape of an elongated bar and are arranged so as to be parallel to the longitudinal direction of the reaction tube 3.

  Here, an upper lamp group 40 composed of, for example, six lamps arranged in the horizontal direction (Y-axis direction in the figure) is provided in the vicinity of the upper horizontal surface portion 30 of the reaction tube 3. In the vicinity of the horizontal surface portion 31 on the side, a lower lamp group 41 composed of, for example, seven lamps arranged in the horizontal direction (Y-axis direction in the figure) is provided.

  Further, in the vicinity of the left arc surface portion 32 of the reaction tube 3, a left lamp group 42 composed of, for example, six lamps arranged along the arc surface portion 32 is provided. In the vicinity of the surface portion 33, a right lamp group 43 including, for example, six lamps arranged along the circular arc surface portion 33 is provided.

In the case of the present invention, the lamp used for the heating means 4 is not particularly limited. However, from the viewpoint of efficient heating, a lamp that includes light having a wavelength of 200 nm to a far infrared region is used. It is preferable to use it.
Around the upper lamp group 40, the lower lamp group 41, the left lamp group 42, and the right lamp group 43, a reflector 10 for reflecting each light is provided.

FIG. 4 is an explanatory diagram showing the arrangement of the upper lamp group and the lower lamp group in the present embodiment.
As shown in FIG. 4, in the present embodiment, the six lamps in the upper lamp group 40 are arranged at the same pitch P.
The seven lamps in the lower lamp group 41 are also arranged at the same pitch P.

The upper lamp group 40 and the lower lamp group 41 are arranged at positions where the lamps do not overlap in the vertical direction (Z-axis direction in the figure).
In the present embodiment, for example, as indicated by reference lines M and N in FIG. 4, the upper lamp group 40 and the lower lamp group 41 are arranged in a horizontal direction (in the figure, a direction orthogonal to the longitudinal direction of the reaction tube 3). In the (Y-axis direction), it is arranged to be displaced by half the pitch P, that is, P / 2.

In the present embodiment having such a configuration, when the object to be heated 21 is heat-treated, the object to be heated 21 is carried into the reaction tube 3 and placed on the susceptor 20.
Then, the reaction gas is introduced into the reaction tube 3 from the gas supply source 8 and the heating means 4 is operated to irradiate the object to be heated 21 with light. In this case, light irradiation is performed so that the temperature of the heated body 21 becomes 1200 ° C. or higher.

On the other hand, the cooling means 7 is operated, the cooling medium is introduced and exhausted, and the reaction tube 3 and the heating means 4 are cooled. Thereby, the temperature of the reaction tube 3 is maintained at about 500 degreeC.
During the heat treatment, the gas detector 22 is operated to detect the concentration of residual gas such as impurity gas in the reaction tube 3. Then, the exhaust amount is controlled based on the result obtained in the gas detector 22.

According to the embodiment described above, even if the heated object 21 is large, the reaction tube 3 is formed by making the cross-sectional shape in the longitudinal direction of the elongated reaction tube 3 made of quartz into an oval shape. The distance between the lamp of the heating means 4 and the object to be heated 21 can be kept shorter than that of the prior art with respect to the object to be heated 21 arranged in the long axis direction. Since heating efficiency is not lowered when heating, high-temperature heat treatment can be performed on the object 21 to be heated.
And according to this Embodiment, since the reaction tube 3 is not heated directly, generation | occurrence | production of impurity gas can be decreased very much and, thereby, heat processing can be performed in a clean atmosphere.

  On the other hand, in the cold wall type lamp heating, it is difficult to maintain in-plane temperature uniformity at a high temperature as compared with a normal hot wall furnace. Among the lamps, an upper lamp group 40 and a lower lamp group 41, which are arranged on the upper side and the lower side of the heated body 21 so as to sandwich the heated body 21, are vertically related. Since it is arranged at a position where it does not overlap, it is possible to uniformly irradiate the heated body 21 with light, so that it is possible to maintain the in-plane uniformity of the temperature of the heated body 21.

  Further, in the present embodiment, since at least the surface layer portion of the susceptor 20 for supporting the heated object 21 is made of a silicon carbide light absorber, the heated object 21 having a shape that is difficult to directly heat by light irradiation. Also, the heat treatment can be performed by heating through the susceptor 20.

  Furthermore, in the present embodiment, since the gas detector 22 for detecting the residual gas in the reaction tube 3 is provided, the exhaust gas is exhausted based on the result obtained by the gas detector 22 so that it is always clean. It becomes possible to perform heat treatment in a simple atmosphere.

  In addition, in the present embodiment, when the reaction tube 3 and the heating unit 4 are provided with the cooling unit 7 that cools the reaction tube 3 and the heating unit 4 with a cooling medium, the temperature of the reaction tube 3 can be kept low. Quartz that could not be used conventionally can be used.

The present invention is not limited to the above-described embodiment, and various changes can be made.
For example, in the above embodiment, the case where a silicon carbide substrate is heated as an object to be heated has been described as an example. However, the present invention is not limited to this, and can be applied to a case where heat treatment is performed on a Si substrate or the like.
However, the present invention is most effective when the silicon carbide substrate is heat-treated at a high temperature of 1200 ° C. or higher to form an oxide film.

Moreover, in the said embodiment, although the to-be-heated body was arrange | positioned in the horizontal surface direction, this invention is not limited to this, For example, it can apply also when arrange | positioning a to-be-heated body in the perpendicular direction.
In this case, for example, the relative positional relationship between the lamps of the heating means is the same as that in the above embodiment, so that the object of the present invention can be achieved.

DESCRIPTION OF SYMBOLS 1 ... Heat processing apparatus 2 ... Apparatus main body 3 ... Reaction tube 4 ... Heating means 7 ... Cooling means 20 ... Susceptor 21 ... Heated object 22 ... Gas detector 30, 31 ... Horizontal surface part 32, 33 ... Arc surface part 40 ... Upper lamp Group 41 ... Lower lamp group

Claims (6)

The device body;
In the apparatus main body, a reaction gas can be introduced and formed into an elongated shape, and a light-transmitting reaction tube that accommodates a plate-shaped object to be heated;
A light irradiation heating means disposed outside the reaction tube in the apparatus main body, and having a lamp for irradiating and heating the object to be heated;
The reaction tube is a heat treatment apparatus in which a cross-sectional shape in the longitudinal direction is formed in an oval shape.   The light irradiation heating means has a plurality of rod-shaped lamps extending in the longitudinal direction of the reaction tube, and is disposed above and below the heated body so as to sandwich the heated body among the plurality of lamps. The heat treatment apparatus according to claim 1, wherein the upper lamp group and the lower lamp group made up of a plurality of lamps are arranged at positions where the lamps do not overlap with each other in the vertical direction.   The heat treatment apparatus according to claim 1, further comprising a susceptor for supporting the object to be heated, wherein at least a surface layer portion of the susceptor is made of a silicon carbide light absorber.   The heat treatment apparatus according to claim 1, wherein the reaction tube is made of quartz.   The heat processing apparatus of any one of Claims 1 thru | or 4 which has a gas detector which detects the residual gas in the said reaction tube.   The heat treatment apparatus according to claim 1, further comprising a cooling unit that cools the reaction tube and the light irradiation heating unit with a cooling medium.

Images