JP2011119391A - Susceptor for epitaxial growth, and epitaxial growth device using the susceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a susceptor for epitaxial growth that is prevented from anchoring to a wafer, and to provide an epitaxial growth device using the susceptor. <P>SOLUTION: The susceptor for epitaxial growth that is arranged horizontally in an epitaxial furnace and has a counterboring part for storing a wafer on an upper surface is characterized in having an isolating member, whose thermal conductivity is lower than that of a susceptor body, at least at a part of a side wall forming the counterboring part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an epitaxial growth susceptor and an epitaxial growth apparatus using the susceptor, and more particularly, to prevent adhesion between a wafer and a susceptor.

FIG. 1 is a diagram showing a conventional epitaxial growth apparatus. The epitaxial growth apparatus 1 includes a horizontally installed susceptor 3 for placing the wafer 2, a heating apparatus 4 for heating the inside of the furnace, a susceptor support 5 for supporting the susceptor, and a rotor 6 for rotating the susceptor. The upper liner 7 and the lower liner 8 for maintaining airtightness are provided, and the furnace 1 is defined by the upper dome 9 and the low wardome 10.
In general, silicon epitaxial growth using a single wafer type apparatus is performed by placing a wafer 2 on a susceptor 3 installed horizontally by a susceptor support 5 in the epitaxial growth apparatus 1 as shown in FIG. An epitaxial film is formed on the wafer 2 by supplying the source gas in the horizontal direction along the upper surface of the susceptor 3 while being rotated by the heating mechanism 4 and performing a heat treatment.
At this time, in order to bring only the upper surface of the wafer 2 into contact with the source gas, the wafer 2 is accommodated and placed in a counterbore portion 3a of the susceptor (a circular recess provided on the susceptor upper surface).
To place the wafer 2 on the counterbore 3a of the susceptor, move the wafer 2 while holding it by vacuum suction on the transfer arm of the transfer robot, release the vacuum suction above the counterbore 3a, and move from the transfer arm. It is common to drop it toward the counterbore part 3a.
When trying to place a wafer on the counterbore part 2a of the susceptor in such a manner, even if the center part of the counterbore part 2a is targeted, it may be placed at a position slightly shifted from the center part as a result. Many.

That is, as shown in FIG. 2, when the wafer 2 is placed on the counterbore portion 3a of the susceptor, the susceptor 3 and the wafer 2 are placed offset in the counterbore portion 3a of the susceptor, and the counterbore portion 2a is The partitioning side wall 3b and the wafer peripheral surface 2a are in partial contact with each other. Further, even if the wafer 2 is eliminated from being offset and placed in the counterbore portion 3a of the susceptor, the susceptor 3 rotates during the epitaxial growth, and the wafer 2 accommodated in the counterbore portion 3a moves, As a result, the side wall 3b partitioning the counterbore part 2a and the wafer peripheral surface 2a are partially in contact with each other.
When epitaxial growth is performed in such a state, precipitates may be generated across the counterbore side wall 3b and the wafer peripheral surface 2a, and the susceptor 3 and the wafer 2 may be fixed.
When this sticking occurs, there is a possibility that silicon peeled off when the wafer 2 is taken out from the epitaxial growth apparatus 1 after the end of the epitaxial growth becomes a burn-in defect or a crack.
The crack causes a wafer crack during the heat treatment in the subsequent device process, and the burn-in defect causes an exposure defect in the device process, causes a device defect and causes a decrease in yield.

  On the other hand, in Patent Document 1, by setting the diameter of the counterbore part and the diameter of the wafer to have a predetermined relationship, a gap between the edge of the wafer and the side wall of the counterbore part is secured, and the wafer A technique for preventing adhesion between the susceptor and the susceptor is disclosed.

Japanese Unexamined Patent Publication No. 2006-351865

  However, even if such a method is used, as described above, it is not possible to avoid the wafer being placed in the counterbore part of the susceptor, and the wafer and the susceptor can be completely prevented from sticking. There wasn't.

  An object of the present invention is to prevent the wafer and the susceptor from sticking and to prevent the occurrence of seizure defects and cracks.

As a result of diligent research on the method for preventing adhesion between the susceptor and the wafer, the present inventors have found that silicon adhesion occurs when the raw silicon atoms reach the growth point (kink) and grow from this point. Therefore, the present inventors have obtained new knowledge that the adhesion between the wafer and the susceptor can be prevented by preventing the temperature from reaching the growth point.
That is, the inventor prevents reaching a temperature at which silicon can be grown in a rapid heating furnace such as an epitaxial growth furnace by interposing a spacer having a low thermal conductivity in the side wall portion of the susceptor in contact with the wafer. As a result, the inventors have obtained new knowledge that the growth of the silicon on the side wall side can be prevented and the adhesion between the wafer and the susceptor can be prevented.

The gist configuration of the present invention for solving the above-described problems is as follows.
(1) A susceptor that is disposed in an epitaxial furnace and has a counterbore part that accommodates a wafer on its upper surface,
The susceptor is composed of carbon, silicon carbide, or a carbon base material coated with silicon carbide, and the thermal conductivity of at least a part of the side wall forming the counterbore part is higher than the thermal conductivity of the susceptor body. A susceptor for epitaxial growth, characterized by having a low spacing material.

  (2) The susceptor for epitaxial growth according to (1), wherein the spacer is made of quartz or silicon nitride.

  (3) The susceptor for epitaxial growth according to (1) or (2), wherein the spacer is made of opaque quartz.

  (4) The susceptor for epitaxial growth according to any one of (1) to (3), wherein the spacer is formed by coating the side wall.

  (5) The susceptor for epitaxial growth according to any one of (1) to (4), wherein the spacing member is provided at three or more locations on the entire side wall or at equal intervals.

(6) An epitaxial growth apparatus comprising a susceptor that accommodates a wafer, a support portion that supports the susceptor, a rotation mechanism that rotates the susceptor, and a heating mechanism.
An epitaxial growth apparatus, wherein the susceptor is the susceptor for epitaxial growth according to any one of (1) to (5).

  (7) The epitaxial growth apparatus according to (6), wherein the heating mechanism is an infrared lamp heating furnace.

  According to the present invention, the separation between the wafer and the susceptor can be prevented by interposing the spacing member having a low thermal conductivity at the portion of the susceptor that contacts the wafer.

It is a figure which shows the conventional epitaxial growth apparatus. It is a figure which shows a mode that the counterbore part side wall and wafer of a susceptor adhere. It is a figure which shows embodiment of this invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 3 (a) shows a susceptor according to one embodiment of the present invention.
As shown in FIG. 3 (a), the susceptor 3 is made of carbon, silicon carbide, or a carbon base material coated with silicon carbide, and comes into contact with the inner surface of the counterbore side wall 3b of the susceptor body 3c. An annular spacing material 3d is fitted to the base.
Here, it is important that the spacer 3d has a lower thermal conductivity than the susceptor body 3c.
Note that “low thermal conductivity” means that the thermal conductivity at 800 to 1200 ° C. that passes through the epitaxial growth process is low.
Hereinafter, the operation of the susceptor having the spacer 3d will be described in detail.

In the epitaxial growth apparatus shown in FIG. 1, the susceptor 3 shown in FIG. 3A is used, and the source gas is introduced while the susceptor is rotated by the rotor 12.
At this time, the wafer 2 is in contact with the part of the spacer 3d of the susceptor 3 as shown in the cross-sectional view (lower diagram) of FIG.
When the thermal conductivity of the spacer 3d is lower than the thermal conductivity of the main body 3c, the spacer 3d is in contact with the peripheral surface of the wafer 2 and the spacer 3d during rapid heating in the epitaxial furnace. The temperature at which silicon can be grown is not reached, and the growth of silicon across the peripheral surface of the wafer and the separating material 3d can be prevented, and the wafer and the susceptor can be prevented from sticking.
Note that the thickness of the spacer 3d is preferably 1 mm or more. This is because if the thickness is less than 1 mm, the heat of the susceptor is transmitted, and the effect of suppressing the adhesion between the wafer and the susceptor may be reduced.

When the spacer 3d is provided on a part of the side wall of the counterbored portion of the susceptor, the wafer 2 may be present at equal intervals at three or more points so that the wafer 2 may contact in any direction of the side wall of the counterbored portion of the susceptor. preferable.
Further, the spacing material 3d may be provided at four or more points, or may be provided continuously on the periphery of the side wall.

As another embodiment, as shown in FIG. 3 (b), the side wall of the counterbore part can be coated with a material whose thermal conductivity is lower than that of the susceptor body 3c.
Further, as in the case of the embodiment shown in FIG. 3 (a), as shown in the cross-sectional view (below) in FIG. 3 (b), the wafer 2 and the spacing material (coating portion) 3e having a low thermal conductivity. You will be in touch.
As a result, at the portion where the edge of the wafer 2 and the spacer (coating portion) 3e are in contact with each other during rapid heating, the spacer 3e does not reach a temperature at which silicon can grow, and the peripheral surface of the wafer and the spacer 3e It is possible to prevent the growth of silicon straddling and prevent the wafer and the susceptor from sticking to each other.
In this embodiment, as shown in FIG. 3 (b), the entire side wall of the counterbore part of the susceptor can be coated, or a part of the side wall of the counterbore part of the susceptor can be coated.
When coating a part of the side wall of the counterbore part of the susceptor, it is preferable to coat the wafer 2 at three or more locations at equal intervals so that the wafer 2 may contact in any direction of the side wall of the counterbore part of the susceptor. Further, as in the case of the susceptor of FIG. 3 (a) described above, the thickness of the coating is preferably 1 mm.

Furthermore, as another embodiment, as shown in FIG. 3 (c), a spacer 3f having a low thermal conductivity, for example, but not particularly limited, is formed in a pin shape, for example, and the side wall of the counterbore part of the susceptor and the wafer It can also be interposed between the two.
As shown in FIG. 3 (c), when the pin-shaped spacer 3f is prepared, the susceptor body 3c and the wafer peripheral surface are fixed by being partially embedded in the side wall or bottom surface of the counterbore portion 3f of the susceptor. And can not touch. Besides embedding the pin-shaped spacer 3f, for example, an arc-shaped spacer can be adhered along the side wall of the susceptor.
At this time, the wafer 2 is in contact with the spacing material 3f having a low thermal conductivity, as shown in the cross-sectional view of FIG. In the part where the material 3f comes into contact, the spacing material 3f does not reach a temperature at which silicon can grow, and prevents silicon from growing between the peripheral surface of the wafer and the spacing material 3f, thereby preventing adhesion between the wafer and the susceptor. Can do.
The spacing members 3f are preferably provided at equal intervals at three or more locations so that the wafer 2 may contact in any direction of the side wall of the counterbore portion of the susceptor. Also in this embodiment, the thickness of the spacer 3f is preferably 1 mm or more.

  As illustrated in these embodiments, according to the present invention, a spacer having a thermal conductivity lower than that of the susceptor body is interposed between the counterbore side wall of the susceptor and the wafer, thereby separating the spacer. The material does not reach a temperature at which silicon can be grown, so that the growth of silicon across the peripheral surface of the wafer and the spacing material can be prevented, and the wafer and the susceptor can be prevented from sticking.

It is preferable to use quartz (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ) as a material having a thermal conductivity lower than that of the susceptor body. This is because the thermal conductivities of SiO ₂ and Si ₃ N ₄ are lower than those of carbon and carbon base materials coated with silicon carbide and SiC. Further, SiO ₂ and Si ₃ N ₄ are high in purity and excellent in heat resistance.
Since SiO ₂ has particularly low thermal conductivity and high purity, it is more preferable as a spacing material used in the present invention.

Further, SiO ₂ is preferably opaque quartz. This is because the opaque quartz has pores, and the thermal conductivity is low due to the presence of the pores.

The susceptor according to the present invention is preferably used in an infrared lamp heating type epitaxial growth apparatus.
For example, SiO ₂ and carbon have different infrared absorbances, so when heated by an infrared lamp, the susceptor made of carbon instantaneously heats up, and SiO ₂ absorbs almost no heat and has a low temperature. This is because the effect of preventing adhesion between the susceptor and the susceptor is increased.

1 is used as an example of the present invention, and each susceptor shown in FIGS. 3 (a) to 3 (c) is used as an example of the present invention, and a conventional susceptor having no spacer is used as a comparative example. The epitaxial growth process was performed. Except for changing the susceptor, all were carried out under the same epitaxial conditions described below.
Using an n-type single crystal silicon wafer with a diameter of 300 mm, surface orientation (100), specific resistance of 20 mΩ · cm, and an oxide film for preventing auto-doping on the back surface, the susceptor on which the wafer was placed was rotated horizontally. After hydrogen baking in the state of the epitaxial apparatus, a mixed reaction gas obtained by diluting SiHCl _{3 as} a silicon source and PH ₃ as a dopant source with hydrogen gas is supplied into the chamber of the epitaxial growth apparatus at a growth temperature of 1150 ° C. A P-type epitaxial silicon film having a thickness of about 100 μm and a specific resistance of 15 Ω · cm was grown. The presence or absence of adhesion between the wafer and the susceptor was visually observed after the epitaxial growth treatment. In each susceptor, the number of epitaxial growth tests was 100, and the results of the sticking occurrence rate at that time are shown in Table 1.

  As is apparent from Table 1, in the example of the present invention in which a spacer having a low thermal conductivity was interposed in the portion of the susceptor that was in contact with the wafer, no adhesion between the wafer and the susceptor was observed.

  The epitaxial growth susceptor of the present invention can reliably prevent the wafer and the susceptor from sticking by interposing a spacer having a low thermal conductivity at the portion of the susceptor in contact with the wafer. In particular, its function is effectively exhibited in the manufacture of epitaxial silicon wafers having a large epitaxial film thickness, such as insulated gate bipolar transistors (IGBTs).

1 Epitaxial growth equipment
2 wafers
2a Wafer peripheral surface
3 Susceptor
3a Counterbore part of susceptor
3b Side wall of counterbore part of susceptor
3c susceptor body
3d spacing material (ring)
3e Spacer (Coating)
3f Spacing material (pin)
4 Heating mechanism
5 Susceptor support
6 Rotor
7 Upper liner
8 Lower liner
9 Upper dome
10 Lowwardome
A Sticking occurs
B Epitaxial film

Claims (7)

A susceptor having a counterbore portion disposed in an epitaxial furnace and containing a wafer on an upper surface thereof;
The susceptor is composed of carbon, silicon carbide, or a carbon base material coated with silicon carbide, and the thermal conductivity of at least a part of the side wall forming the counterbore part is higher than the thermal conductivity of the susceptor body. A susceptor for epitaxial growth, characterized by having a low spacing material.   The susceptor for epitaxial growth according to claim 1, wherein the spacer is made of quartz or silicon nitride.   The susceptor for epitaxial growth according to claim 1, wherein the spacer is made of opaque quartz.   The susceptor for epitaxial growth according to any one of claims 1 to 3, wherein the spacer is formed by coating the side wall.   The susceptor for epitaxial growth according to any one of claims 1 to 4, wherein the spacing member is provided at three or more locations on the entire surface of the side wall or at equal intervals. An epitaxial growth apparatus comprising: a susceptor that accommodates a wafer; a support that supports the susceptor; a rotation mechanism that rotates the susceptor; and a heating mechanism.
6. The epitaxial growth apparatus according to claim 1, wherein the susceptor is the susceptor for epitaxial growth according to any one of claims 1 to 5. 7. The epitaxial growth apparatus according to claim 6, wherein the heating mechanism is an infrared lamp heating furnace.

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