JP2011105999A - Method for manufacturing heater, and film deposition system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a heater which is usable for the epitaxial growth of an SiC film. <P>SOLUTION: The heater includes a heating element heat-generated by energization. The heating element can be obtained, after the obtainment of an SiC sintered compact 1 having prescribed shape and electric specific resistance, by coating the surface of the SiC sintered compact 1 with a plurality layers of SiC thin films 2 to 5. The plurality of layers of the SiC thin films 2 to 5 are formed respectively at different film deposition temperatures, and the film deposition temperature is higher as it goes to the external side layer. Respective film deposition temperatures are preferably controlled to 1,400°C±50°C, 1,600±50°C, 1,800±50°C, and 2,000°C±50°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a heater and a film forming apparatus using the heater manufactured by this method.

  In manufacturing an epitaxial wafer in which a single crystal film such as silicon is formed on the surface of a wafer, a single wafer type film forming apparatus is often used.

  The film forming apparatus is configured to supply a reaction gas into a film forming chamber containing a susceptor on which a wafer is placed and to heat the back surface of the wafer to form an epitaxial film on the surface of the wafer. Such a backside heating method does not have a heating source above and can supply a reaction gas in the vertical direction, so that a uniform film formation process is possible.

  In addition, the film forming apparatus is connected to a support member for the susceptor at the upper end, and is provided for a rotating shaft extending downward through a through hole formed in the bottom wall portion of the film forming chamber and for a rotating shaft disposed below the film forming chamber. The rotation mechanism unit is arranged and the wafer is rotated during film formation, so that a film having a more uniform thickness is formed (for example, see Patent Document 1).

  A resistance heater is used as a heating source of the film forming apparatus. The heater is made of a material that does not deform at high temperatures and does not release contaminants. Specifically, SiC (silicon carbide) is used as a constituent material of the heater.

  For example, in the case of epitaxial growth of a Si (silicon) film, the wafer temperature is heated to about 1200 ° C. At this time, the temperature of the heater is higher than this. Therefore, it is required that there is no deformation or release of contaminants at this temperature. A heater that can be used for such applications includes a heater made of sintered SiC, but the usable temperature range is up to about 1400 ° C.

JP-A-5-152207

  In recent years, SiC has attracted attention as a material for power semiconductor devices having a high withstand voltage in place of Si. SiC is characterized by an energy gap that is two to three times larger than that of conventional semiconductor materials such as Si and GaAs (gallium arsenide), and a dielectric breakdown voltage that is about an order of magnitude higher.

For example, the SiC film is formed on a SiC wafer by using H ₂ (hydrogen) as a carrier gas and supplying SiH ₄ (monosilane) and C ₃ H ₈ (propane). Specifically, these gases supplied into the film formation chamber are circulated in a laminar flow around the surface area of the SiC wafer placed on the heated susceptor and exhausted until the SiC wafer is exhausted. Causes an epitaxial growth reaction on the surface. At this time, the epitaxial growth of the SiC film is performed at a higher temperature than in the case of the Si film. For this reason, the temperature of the heater becomes even higher, for example, about 2000 ° C. However, none of the conventional heaters can withstand such temperatures. This is because Si sublimation occurs due to the presence of H ₂ gas or the like.

  The present invention has been made in view of these problems. That is, an object of the present invention is to provide a method for manufacturing a heater that can be used for epitaxial growth of a SiC film.

  Another object of the present invention is to provide a film forming apparatus capable of forming a predetermined film on a substrate while heating the substrate at a high temperature.

  Other objects and advantages of the present invention will become apparent from the following description.

A first aspect of the present invention is a method for manufacturing a heater including a heating element that generates heat when energized.
Obtaining a SiC sintered body having a predetermined shape and electrical resistivity;
A step of coating the surface of the SiC sintered body with a plurality of layers of SiC thin film to obtain a heating element,
The plurality of layers of SiC thin films are formed at different film formation temperatures, and the outer layer has a higher film formation temperature.

  In the first aspect of the present invention, in the step of obtaining the heating element, it is preferable to form the first SiC thin film in contact with the SiC sintered body at 1400 ° C. ± 50 ° C.

In the first aspect of the present invention, the step of obtaining the heating element includes the step of forming a first SiC thin film at 1400 ° C. ± 50 ° C. on the surface of the SiC sintered body,
Forming a second SiC thin film at 1600 ° C. ± 50 ° C. on the surface of the first SiC thin film;
Forming a third SiC thin film at 1800 ° C. ± 50 ° C. on the surface of the second SiC thin film;
It is preferable to have a step of forming a fourth SiC thin film on the surface of the third SiC thin film at 2000 ° C. ± 50 ° C.

A second aspect of the present invention includes a film formation chamber,
In a film forming apparatus provided with a heater for heating a substrate placed in the film forming chamber,
The heater has a heating element that generates heat when energized.
The heating element is characterized in that the surface of the SiC sintered body is covered with a plurality of layers of SiC thin film, and the plurality of layers of SiC thin film are formed at higher film forming temperatures in the outer layers. It is.

In a second aspect of the present invention, a susceptor on which a substrate is placed;
A support part in which the susceptor is arranged at the top and the heater is arranged inside;
It is preferable that a rotation shaft provided at a lower portion of the film formation chamber to rotate the support portion is provided.

  According to the first aspect of the present invention, a plurality of layers of SiC thin films are formed at different film formation temperatures, and the outer layer has a higher film formation temperature, so that a heater that can be used for epitaxial growth of SiC films is manufactured. Is done.

  According to the second aspect of the present invention, the heater includes a heating element in which a surface of a SiC sintered body is coated with a plurality of layers of SiC thin film, and an electrode that energizes the heating element to raise the temperature of the heating element. The multiple layers of SiC thin films are formed at different film forming temperatures, and the outer layers have higher film forming temperatures. Therefore, a predetermined film is formed on the substrate while heating the substrate at a high temperature. It can be set as the film-forming apparatus which can do.

It is typical sectional drawing of the film-forming apparatus in this Embodiment. It is sectional drawing which showed a mode that SiC coating was performed to a SiC sintered compact. It is an example of the top view of the heater in this Embodiment.

  FIG. 1 is a schematic cross-sectional view of a single wafer deposition apparatus 100 according to the present embodiment. In the present embodiment, SiC wafer 101 is used as the substrate. However, the present invention is not limited to this, and a wafer made of another material may be used according to circumstances.

  The film formation apparatus 100 includes a chamber 103 as a film formation chamber.

  A gas supply unit 123 that supplies a source gas for forming a crystal film on the surface of the heated SiC wafer 101 is provided on the upper portion of the chamber 103. In addition, a shower plate 124 in which a large number of source gas discharge holes are formed is connected to the gas supply unit 123. By disposing the shower plate 124 so as to face the surface of the SiC wafer 101, the source gas can be supplied to the surface of the SiC wafer 101.

As source gases, SiH ₄ (monosilane) and C ₃ H ₈ (propane) can be used, and are introduced into the chamber 103 from the gas supply unit 123 in a state of being mixed with hydrogen gas as a carrier gas. In place of SiH ₄ , SiH ₆ (disilane), SiH ₃ Cl (monochlorosilane), SiH ₂ Cl ₂ (dichlorosilane), SiHCl ₃ (trichlorosilane), SiCl ₄ (tetrachlorosilane), or the like may be used. .

  A plurality of gas exhaust parts 125 for exhausting the source gas after the reaction are provided in the lower part of the chamber 103. The gas exhaust unit 125 is connected to an exhaust mechanism 128 including a regulating valve 126 and a vacuum pump 127. The exhaust mechanism 128 is controlled by a control mechanism (not shown) to adjust the inside of the chamber 103 to a predetermined pressure.

  A susceptor 102 is provided on the rotating unit 104 inside the chamber 103. The susceptor 102 includes a first susceptor portion 102a that supports the outer peripheral portion of the SiC wafer 101, and a second susceptor portion 102b that is closely fitted in an opening portion of the first susceptor portion 102a. Since the first susceptor portion 102a and the second susceptor portion 102b are exposed to a high temperature, they are configured using, for example, high-purity SiC.

  The susceptor 102 may be a combination of the first susceptor part 102a and the second susceptor part 102b. Further, the susceptor 102 may be configured by only the first susceptor part 102a without the second susceptor part 102b. However, in order to prevent the SiC wafer 101 from being contaminated by contaminants generated in the heater 120 and the rotating unit 104, the second susceptor unit 102b is preferably provided.

  The rotating unit 104 includes a rotating drum 104a, a rotating base 104b, and a rotating shaft 104c. The rotating drum 104a that supports the susceptor 102 is fixed on the rotating base 104b. The rotating drum 104a corresponds to the support portion of the present invention, and the susceptor 102 is disposed in the upper portion and the heater 120 is disposed in the upper portion. The rotation base 104b is connected to the rotation shaft 104c by a screw 106.

  The rotation shaft 104c extends to the outside of the chamber 103 and is connected to a rotation mechanism (not shown). By rotating the rotating shaft 104c, the susceptor 102 can be rotated via the rotating base 104b and the rotating drum 104a, and the SiC wafer 101 supported by the susceptor 102 can be rotated. By rotating the SiC wafer 101 during film formation, a film having a uniform thickness can be formed. The rotating drum 104a preferably rotates about a line passing through the center of the SiC wafer 101 and orthogonal to the SiC wafer 101.

In Figure 1, rotary cylinder 104a is a structure in which the upper is released, by the susceptor 102 is provided, the hollow region (hereinafter, referred to as P ₂ region.) Top covered to form a. Incidentally, if there is no second susceptor portion 102b is, _{P 2} region is formed by the SiC wafer 101 is supported by the first susceptor portion 102a. Here, if the inside of the chamber 103 is a P ₁ region, the P ₂ region is a region substantially separated from the P ₁ region by the susceptor 102.

The area P _2, a heater 120 for heating the SiC wafer 101 from the back surface is provided. The heater 120 is supported by an arm-shaped booth bar 121. Booth bar 121 is connected to electrode 122 at the end opposite to the side supporting heater 120.

  The heater 120 is manufactured by the method of the present embodiment described later. The booth bar 121 is made of a conductive high heat resistant member, for example, a C (carbon) material coated with SiC. The electrode 122 is made of Mo (molybdenum). Thus, power can be supplied from the electrode 122 to the heater 120 via the booth bar 121 which is a heater support portion. Specifically, electricity is supplied from the electrode 122 to a heating element of the heater 120 described later, and the heating element is heated.

  In the present embodiment, SiC wafer 101 may be heated by two types of heaters, an in-heater and an out-heater. In this case, the outheater can mainly heat the peripheral portion of the susceptor 102, and the inheater can be disposed below the outheater to mainly heat the portion other than the peripheral portion of the susceptor 102. By doing so, the SiC wafer 101 can be heated more uniformly, so that the uniformity of the temperature distribution of the SiC wafer 101 is improved.

  The surface temperature of the SiC wafer 101 that changes due to heating is measured by a radiation thermometer 140 provided in the upper part of the chamber 103. The radiation thermometer 140 constitutes a temperature measuring unit in the present invention. The shower plate 124 is made of transparent quartz, so that the temperature measurement by the radiation thermometer 140 can be prevented from being hindered by the shower plate 124. The measured temperature data is sent to a control mechanism (not shown) and then fed back to the output control of the heater 120. Thereby, SiC wafer 101 can be heated to a desired temperature.

  Next, the heater 120 of this embodiment will be described.

  The heater 120 is a SiC heater using a SiC sintered body as a heating element. The SiC sintered body has a fine and uniform structure with few impurities at the grain boundary, and has high conductivity. From the viewpoint of heat resistance, C (carbon) is better than SiC, but it is preferable to use SiC in consideration of the influence of impurities on the epitaxial film.

  The heater 120 has a heating element that generates heat when energized. This heating element is characterized in that the SiC sintered body is coated with SiC, and the SiC coating is composed of a plurality of SiC films sequentially formed at different temperatures.

  The SiC sintered body is obtained by sintering SiC powder. In this case, for example, a plurality of SiC powders having different average particle sizes can be mixed and sintered to form a SiC sintered body. By selecting the average particle diameter of each SiC and the mixing ratio thereof, it is possible to obtain SiC exhibiting a desired electrical specific resistance. The mixture is formed into a desired shape and then sintered at a predetermined temperature. Note that the sintering method and the atmosphere during sintering are not limited.

  SiC coating is performed on the SiC sintered body having the predetermined shape and electrical resistivity obtained as described above. At this time, the SiC sintered body is coated with a plurality of SiC films while gradually increasing the film formation temperature. That is, the surface of the SiC sintered body is covered with a plurality of layers of SiC thin films formed at different temperatures. In the multilayered SiC thin film, the outer layer has a higher film forming temperature.

FIG. 2 is a cross-sectional view showing a state in which the SiC sintered body is coated with SiC. As shown in this figure, first, the SiC sintered body 1 is heated to a temperature T ₁ , and a first layer SiC film 2 is formed on the surface of the SiC sintered body 1 by a CVD (Chemical Vapor Deposition) method (see FIG. 2 (a)). Next, the temperature of the SiC sintered body 1 is raised to a temperature T ₂ (T ₂ > T ₁ ), and a second-layer SiC film 3 is formed on the first-layer SiC film 2 in the same manner (FIG. 2). (B)). Next, the temperature of the SiC sintered body 1 is raised to a temperature T ₃ (T ₃ > T ₂ ), and a third-layer SiC film 4 is formed on the second-layer SiC film 3 (FIG. 2C). . Further, the SiC sintered body 1 is heated to a temperature T ₄ (T ₄ > T ₃ ), and a fourth SiC film 5 is formed on the third SiC film 4 (FIG. 2D). . Each film thickness of the SiC layers 2 to 5 is preferably about several tens of μm, for example, 50 μm.

When it is desired to set the usable temperature range of the heater up to about 2000 ° C., for example, T ₁ = 1400 ° C., T ₂ = 1600 ° C., T ₃ = 1800 ° C., and T ₄ = 2000 ° C. are preferable. Here, T ₁ = 1400 ° C. is because the heat resistance of SiC is about 1400 ° C. Further, T ₄ = 2000 ° C. takes into consideration the desired usable temperature range. In this case, each film forming temperature may be raised or lowered within a range of ± 50 ° C. By changing the film formation temperature stepwise, it is possible to prevent cracks from occurring in the SiC sintered body or the SiC film. This effect is more easily obtained when the film forming temperature is changed finely, but the actual number of steps is determined in consideration of the temperature controllability and productivity on the film forming apparatus side. Note that the temperature may be raised by energizing the SiC sintered body 1 and heating it with electric resistance.

  FIG. 3 is an example of a plan view of the heater 120. In this figure, the heater 120 is obtained by processing a SiC-coated SiC sintered body into a strip shape, and combining a plurality of them into a disk shape. Note that FIG. 2D corresponds to a cross-sectional view taken along the line A-A ′ of FIG. 3.

  As described above, when the SiC sintered body is coated with SiC while gradually increasing the film forming temperature, a heater having excellent heat resistance can be manufactured. In other words, when one layer of SiC coating is applied to the SiC sintered body, heat resistance can be improved as compared with the SiC sintered body alone, but further, by applying a plurality of layers of SiC coating while gradually changing the film forming temperature. , It can be made more excellent in heat resistance. For example, the usable temperature range of a heater made of sintered SiC is up to about 1400 ° C., but the usable temperature range of a heater in which an SiC coat is formed on one layer of a SiC sintered body is up to about 1600 ° C. And the usable temperature range of the heater manufactured by the method of this Embodiment improves to about 2000 degreeC.

  An example of a film forming method according to this embodiment will be described with reference to FIG.

First, the SiC wafer 101 is placed on the susceptor 102, and the SiC wafer 101 is rotated at about 50 rpm in association with the rotating unit 104 while flowing H ₂ (hydrogen) gas under a reduced pressure of several tens of torr, for example. .

  Next, the SiC wafer 101 is gradually heated to the film formation temperature by the heater 120. In the heater 120, the SiC sintered body is coated with SiC, and the SiC coat is composed of a plurality of SiC films sequentially formed at different temperatures. Therefore, the heater 120 has sufficient heat resistance even at a high temperature of about 2000 ° C. It is possible to have.

After confirming that the temperature of the SiC wafer 101 has reached the film formation temperature by measurement with the radiation thermometer 140, the rotational speed of the SiC wafer 101 is gradually increased. Then, the source gas is supplied from the gas supply unit 123 into the chamber 103 through the shower plate 124. In the present embodiment, SiH ₄ (monosilane) and C ₃ H ₈ (propane) can be used as source gases, and in a state mixed with H ₂ gas as a carrier gas, from the gas supply unit 123 to the chamber 103. Install inside. In place of SiH ₄ , SiH ₆ (disilane), SiH ₃ Cl (monochlorosilane), SiH ₂ Cl ₂ (dichlorosilane), SiHCl ₃ (trichlorosilane), SiCl ₄ (tetrachlorosilane), or the like may be used. .

  The source gas introduced into the chamber 103 flows down toward the SiC wafer 101. Then, while maintaining the temperature of the SiC wafer 101 at the film formation temperature, new source gases are successively supplied from the gas supply unit 123 to the SiC wafer 101 via the shower plate 124 while rotating the susceptor 102 at a high speed of 900 rpm or higher. To do. Thereby, an epitaxial film can be efficiently formed at a high film formation rate. For example, in a power semiconductor application, a thick film of about 10 μm or more, mostly about 10 μm to 100 μm, is formed on a 300 mm SiC wafer. In order to form a thick film, it is preferable to increase the number of rotations of the substrate during film formation. For example, the number of rotations is about 900 rpm as described above.

  After the film forming process is finished, the temperature of the heater 120 is lowered. When the temperature of SiC wafer 101 is sufficiently lowered, SiC wafer 101 is carried out of chamber 103.

  As described above, the heater manufactured by the method of the present invention has high heat resistance and can be sufficiently used for epitaxial growth of a SiC film. And the film-forming apparatus provided with this heater can form predetermined films, such as a SiC film, on a substrate, heating a substrate under high temperature.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  In the above embodiment, the example in which the film formation process is performed while rotating the wafer placed in the film formation chamber is described, but the present invention is not limited to this. The film forming apparatus of the present invention may form a film without rotating the wafer.

  Moreover, in the said embodiment, although the epitaxial growth apparatus was mentioned as an example of the film-forming apparatus, this invention is not limited to this. Any other film forming apparatus such as a CVD (Chemical Vapor Deposition) apparatus may be used as long as it supplies a reactive gas into the film forming chamber and forms a film on the surface while heating the wafer.

DESCRIPTION OF SYMBOLS 100 ... Film-forming apparatus 101 ... SiC wafer 102 ... Susceptor 103 ... Chamber 104 ... Rotating part 104a ... Rotating drum 104b ... Rotating base 104c ... Rotating shaft 106 ... Screw 120 ... Heater 121 ... Booth bar 122 ... Electrode 123 ... Gas supply part 124 ... Shower plate 125 ... gas exhaust part 126 ... regulating valve 127 ... vacuum pump 128 ... exhaust mechanism 140 ... radiation thermometer

Claims (5)

In the manufacturing method of a heater provided with a heating element that generates heat when energized,
Obtaining a SiC sintered body having a predetermined shape and electrical resistivity;
Covering the surface of the SiC sintered body with a plurality of layers of SiC thin film to obtain the heating element,
The method of manufacturing a heater, wherein the plurality of layers of SiC thin films are formed at different film forming temperatures, and the outer layer has a higher film forming temperature.   2. The method of manufacturing a heater according to claim 1, wherein the step of obtaining the heating element includes forming a first layer SiC thin film in contact with the SiC sintered body at 1400 ° C. ± 50 ° C. 3. The step of obtaining the heating element includes the step of forming a first SiC thin film at 1400 ° C. ± 50 ° C. on the surface of the SiC sintered body,
Forming a second SiC thin film at 1600 ° C. ± 50 ° C. on the surface of the first SiC thin film;
Forming a third SiC thin film at 1800 ° C. ± 50 ° C. on the surface of the second SiC thin film;
3. The method of manufacturing a heater according to claim 1, further comprising: forming a fourth SiC thin film on the surface of the third SiC thin film at 2000 ° C. ± 50 ° C. 3. A deposition chamber;
In a film forming apparatus including a heater for heating a substrate placed in the film forming chamber,
The heater includes a heating element that generates heat when energized,
The heating element is formed by coating a surface of a SiC sintered body with a plurality of layers of SiC thin film, and the plurality of layers of the SiC thin film are formed at a higher film forming temperature in the outer layer. A film forming apparatus. A susceptor on which the substrate is placed;
A support part for disposing the susceptor at the top and disposing the heater inside;
The film forming apparatus according to claim 4, further comprising: a rotating shaft provided at a lower portion of the film forming chamber for rotating the support portion.

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