JP6215798B2 - Susceptor - Google Patents

Description

  The present invention relates to a susceptor having a wafer pocket on a top surface side for placing a wafer.

  Since various members such as semiconductor device jigs (wafer boats, susceptors, holders) for semiconductor heat treatment furnaces used when manufacturing semiconductors require characteristics such as high heat resistance, high durability, and high strength, A silicon carbide substrate using high-purity silicon carbide (SiC) or a carbon (C) substrate coated with a SiC film or the like is widely used. In the conventional susceptor, a CVD-SiC coating is often performed on a graphite base material to provide a susceptor with improved corrosion resistance.

JP 2000-332096 A JP 2010-239020 A

  However, when a susceptor is used for a certain period (several months), the CVD-SiC film is peeled off and impurities are generated from the graphite of the base material. Therefore, it is necessary to replace in a short period of time, and the replacement cost is increased because the life of the susceptor is short.

  In addition, as the diameter of the wafer increases, the size of the wafer mounting surface of the susceptor is also increasing, and the susceptor is increasingly required to have high thermal uniformity.

  For this reason, there is an increasing demand for a susceptor made of high-purity all-SiC, that is, a susceptor composed entirely of high-purity SiC. However, because SiC is poor in workability, it takes time to manufacture the susceptor, and SiC Is a high-cost susceptor due to its high material price.

  Therefore, the present invention has been made to solve the above-described problems, and provides a susceptor capable of extending the life compared to the conventional case even if not all are made of high-purity SiC. Purpose.

  A susceptor according to a first aspect of the present invention is a susceptor having a wafer pocket on which a wafer is placed. The susceptor has the wafer pocket on the upper surface side, and projects downward from a position on the inner peripheral side with respect to the outer peripheral part. An upper member made of silicon carbide having a fitting convex portion on the lower surface side, and a lower member made of silicon carbide having a fitting concave portion in surface contact with the lower surface of the fitting convex portion on the upper surface side to support the upper member. And when the upper member is set on the lower member by inserting the fitting convex portion into the fitting concave portion, the lower member is entirely covered by the upper member in plan view. The outer peripheral portion is covered and is not in contact with the lower member.

  A susceptor according to a second feature of the present invention is a susceptor having a wafer pocket on which a wafer is placed. The susceptor has the wafer pocket on the upper surface side and is recessed upward from a position on the inner peripheral side with respect to the outer peripheral portion. An upper member made of silicon carbide having a fitting concave portion on the lower surface side, and a lower side made of silicon carbide having a fitting convex portion in surface contact with the bottom surface of the fitting concave portion on the upper surface side to support the upper member When the upper member is set on the lower member by inserting the fitting convex portion into the fitting concave portion, the lower member is covered over the entire surface by the upper member in a plan view. And the outer peripheral portion is not in contact with the lower member.

  According to the present invention, it is possible to provide a susceptor capable of extending the life compared to the prior art even if not entirely composed of high-purity SiC.

(A) is a top view which shows the susceptor which concerns on 1st Embodiment, (b) is side sectional drawing of arrow 1b-1b of (a). It is the elements on larger scale of FIG.1 (b). FIG. 3 is a partially enlarged view of FIG. 2. It is side surface sectional drawing which shows the principal part of the susceptor which concerns on 2nd Embodiment.

  Hereinafter, a susceptor according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[First Embodiment]
First, the first embodiment will be described. 1A is a plan view showing a susceptor according to the present embodiment, and FIG. 1B is a side sectional view taken along line 1b-1b in FIG. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a partially enlarged view of FIG.

  As shown in FIGS. 1 to 3, the susceptor 10 of this embodiment includes an upper member 12 and a lower member 14. Each of the upper member 12 and the lower member 14 has a disk shape when viewed from a projection plane parallel to the wafer arrangement surface (that is, in plan view). Upper member 12 is made of high-purity silicon carbide. Lower member 14 is made of silicon carbide having a lower purity than upper member 12.

  The upper member 12 has a wafer pocket 16 for placing a wafer on the upper surface side. In the present embodiment, the upper flange 20 is formed as the outer peripheral portion of the upper member 12. And the upper member 12 has the fitting convex part 22 which protrudes below from the position of the inner peripheral side rather than the upper side collar part 20 on the lower surface side. The lower member 14 is configured to support the upper member 12 by having a fitting concave portion 32 in surface contact with the lower surface 22 b of the fitting convex portion 22 on the upper surface side.

  And when the upper member 12 is set to the lower member 14 by the fitting convex portion 22 being put in the fitting concave portion 32, the lower member 14 is covered over the entire surface by the upper member 12 in a plan view, and The outer peripheral portion of the upper member 12 is not in contact with the lower member 14.

  Further, the lower member 14 is formed with a lower outer peripheral portion 30 (lower heel portion) so as to face the upper heel portion 20 when the upper member 12 is set on the lower member 14. Therefore, when the upper member 12 is set on the lower member 14, a gap G is formed between the upper flange portion 20 and the lower outer peripheral portion 30.

  Further, in the present embodiment, when the upper member 12 is set on the lower member 14, the horizontal position of the wafer pocket 16 is set to the position on the inner peripheral side with respect to the inner peripheral end P of the space forming the gap G. Thus, the formation position of the wafer pocket 16 is determined in advance.

  In the present embodiment, the lower outer peripheral portion 30 projects from the lower member main body 14m constituting the lower member 14 to the outer peripheral side. And the horizontal direction position of the outer peripheral side end 16e of the wafer pocket 16 is located in the inner peripheral side rather than the outer peripheral wall 14e of the lower member main body 14m.

  The upper member 10 is made of high-purity silicon carbide, for example, silicon carbide having a purity of 6N or higher. Here, N represents purity. 3N means a purity of 99.9% and 6N means a purity of 99.9999%. The purity means the purity of the main metal material, which is a value obtained by subtracting metal impurities from 100, and is represented by “100% −metal impurities (%) = purity (%)”.

As a specific detailed example, the upper member 12 is obtained by processing a mixture containing silicon carbide by hot pressing under a temperature condition of 2000 to 2400 ° C. and a pressure condition of 300 to 700 kg / cm ² . When the purity of the silicon carbide of the upper member 12 is 6N or more, a decrease in the heating rate and heat utilization efficiency of the susceptor 10 is suppressed.

  The lower member 14 is stacked on the upper member 12 in a direction orthogonal to the wafer arrangement surface, and supports the upper member 12. That is, the lower member 14 is disposed on the heating source (heater) side with respect to the upper member 12.

The lower member 14 is made of silicon carbide having a purity of 99 to 99.9%, for example. As a specific detailed example, the lower member 14 is obtained by sintering a mixture containing silicon carbide under a temperature condition of 2000 to 2200 ° C. using a sintering aid such as yttria (Y ₂ O ₃ ). can get. Thus, when the lower member 14 is made of silicon carbide, the purity of the silicon carbide constituting the lower member 14 is lower than the purity of the silicon carbide constituting the upper member 12, and is 2N to 3N. A range is preferable. When the purity of the silicon carbide constituting the lower member 14 is 3N or less, the heater pattern is suppressed from being directly transferred to the wafer. On the other hand, when the purity of the silicon carbide constituting the lower member 14 is 2N or more, the temperature increase rate and the heat utilization efficiency of the susceptor 10 are suppressed from decreasing.

  In the present embodiment, the thermal conductivity of the upper member 12 is higher than the thermal conductivity of the lower member 14. For example, the thermal conductivity of the upper member 12 is 200 W / m · K (RT) or more, and the thermal conductivity of the lower member 14 is in the range of 140 to 170 W / m · K (RT). In this case, the reason why the thermal conductivity of the upper member 12 is 200 W / m · K (RT) or higher is the same as the reason that the purity of silicon carbide constituting the upper member 10 is 6 N or higher. The reason why the thermal conductivity of the lower member 14 is in the range of 140 to 170 W / m · K (RT) is the same as the reason that the purity of silicon carbide constituting the lower member 14 is in the range of 2N to 3N. is there.

Further, the thermal resistance value of the upper member 12 is lower than the thermal resistance value of the lower member 14. The thermal resistance value of the upper member 12 is 5.0 × 10 ⁻³ m · K (RT) / W or less, and the thermal resistance value of the lower member 14 is 5.8 × 10 ^{−3 to} 7.1 ×. The range is 10 ⁻³ m · K (RT) / W. When the thermal resistance value of the upper member 12 is 5.0 × 10 ⁻³ m · K (RT) / W or less, a decrease in the temperature increase rate and heat utilization efficiency of the susceptor 10 is suppressed. When the thermal resistance value of the lower member 14 is 5.8 × 10 ⁻³ m · K (RT) / W or more, the transfer of the heater pattern directly to the wafer is suppressed. On the other hand, when the thermal resistance value of the lower member 14 is 7.1 × 10 ⁻³ m · K (RT) / W or less, the temperature increase rate and the heat utilization efficiency of the susceptor 10 are suppressed.

(Function, effect)
Hereinafter, the operation and effect of the present embodiment will be described.

  In the present embodiment, when the upper member 12 is set on the lower member 14 by inserting the fitting convex portion 22 into the fitting concave portion 32, the lower member 14 is covered over the entire surface by the upper member 12 in plan view. . Therefore, the heat of the lower member 14 is prevented from escaping upward from the lower outer peripheral portion 30 and the temperature is partially lowered.

  And when the upper member 12 is set to the lower member 14 by the fitting convex part 22 being put in the fitting concave part 32, the upper flange part 20, which is the outer peripheral part of the upper member 12, It is not in contact with the lower outer peripheral portion 30 that is the outer peripheral portion. Therefore, the downward movement of the upper flange portion 20 is not hindered by the lower outer peripheral portion 30, so that the bottom surface of the fitting convex portion 22 can be reliably brought into surface contact with the bottom surface 32 s of the fitting concave portion 32. Therefore, since the temperature of the upper member 12 can be made uniform, the temperature of the wafer placed in the wafer pocket 16 can be made uniform, and the yield is improved. This effect is particularly significant when the wafer is placed in the wafer pocket 16 because the space in which the susceptor 10 is accommodated is in a vacuum state.

  Further, since the upper flange 20 is not in contact with the lower outer peripheral portion 30, the temperature of the upper flange 20 is likely to be different from that of the fitting protrusion 22 in surface contact with the fitting recess 32. However, in the present embodiment, in the upper member 12, all the wafer pockets 16 are formed on the inner peripheral side with respect to the upper flange portion 20. Therefore, since the temperature of the wafer pocket 16 can be made more uniform, the temperature of the wafer to be placed can be more easily maintained.

  Further, the thermal conductivity of the plate-like upper member 12 having the wafer placement surface is higher than the thermal conductivity of the lower member 14. Accordingly, a decrease in the temperature increase rate and heat utilization efficiency of the susceptor 10 is suppressed. On the other hand, the thermal conductivity of the lower member 14 disposed closer to the heater than the upper member 12 is lower than the thermal conductivity of the upper member 12. Therefore, it is possible to suppress the heater pattern from being directly transferred to the wafer, and to improve the thermal uniformity on the wafer placement surface.

  Further, by disposing the lower member 14 on the heater side with respect to the upper member 12, it becomes difficult for the heat of the susceptor 10 to escape through the support body that supports the susceptor 10.

  In the present embodiment, when the upper member 12 is set on the lower member 14, the gap G formed between the upper flange portion 20 and the lower outer peripheral portion 30 is preferably 0.1 mm or less. . Thereby, it is easy to sufficiently prevent the upper member 12 from coming out of the lower member 14 and jumping out during use of the susceptor 10, and the upper flange portion 20 is reinforced by the lower outer peripheral portion 30. Moreover, it is preferable that the clearance gap G is 1 micrometer or more from a viewpoint of performing degassing reliably.

  Moreover, it is preferable that the clearance gap G is formed over W = 1 mm or more from the outer periphery E of the upper member 12, ie, the outer periphery E of the upper collar 20, to the inner periphery. Thereby, it is easy to surely perform gas venting between the fitting convex portion 22 and the fitting concave portion 32. From the viewpoint of heat uniformity of the susceptor, W is preferably 50 mm or less.

  Moreover, it is preferable that the thickness T of the upper collar part 20 is 1 mm or more. Thereby, the effect of the strength reinforcement of the upper collar part 20 is acquired. In addition, the thickness T is preferably 5 mm or less from the viewpoint of heat uniformity of the susceptor.

  Further, the horizontal distance D between the outer peripheral end 16e of the wafer pocket 16 and the outer peripheral wall 14e of the lower member main body 14m is 2 mm or more, so that the heat uniformity of the wafer pocket 16, that is, the wafer pocket 16 is placed. This is preferable from the viewpoint of the thermal uniformity of the wafer.

  Further, the lower member 14 may be constituted by a carbon (C) base material coated with a SiC film or the like. This further reduces the weight.

[Second Embodiment]
Next, a second embodiment will be described. FIG. 4 is a side sectional view showing the main part of the susceptor according to this embodiment.

  Compared with the first embodiment, the susceptor 40 of the present embodiment has a fitting convex portion and a fitting concave portion formed upside down. That is, the susceptor 40 of this embodiment includes an upper member 42 and a lower member 44. The upper member 42 has an upper outer peripheral portion 50 instead of the upper flange portion 20 as compared with the first embodiment. The size of the lower outer peripheral portion 60 constituting the lower member 44 is determined so as to form a predetermined gap G between the lower outer peripheral portion 60 and the upper outer peripheral portion 50.

  With this structure, the upper member 42 has a fitting concave portion 54 that is recessed upward from a position on the inner peripheral side with respect to the upper outer peripheral portion 50 on the lower surface side. The lower member 44 is configured to support the upper member 42 by having a fitting convex portion 56 in surface contact with the bottom surface (upper surface) 54 b of the fitting concave portion 54 on the upper surface side.

  When the upper member 42 is set on the lower member 44 by inserting the fitting convex portion 56 into the fitting concave portion 54, the lower member 44 is covered by the upper member 42 over the entire surface in a plan view, and The upper outer peripheral portion 50 is not in contact with the lower outer peripheral portion 60. That is, when the upper member 42 is set on the lower member 44, a gap G is formed between the upper outer peripheral portion 50 and the lower outer peripheral portion 60.

  Further, in the present embodiment, when the upper member 42 is set on the lower member 44, the horizontal position of the wafer pocket 16 is all positioned on the inner peripheral side with respect to the upper outer peripheral portion 50. The formation position is predetermined.

  The upper member 42 is made of high-purity silicon carbide. The lower member 44 is made of silicon carbide having a lower purity than the upper member 42. According to the present embodiment, the same effects as those of the first embodiment are exhibited.

DESCRIPTION OF SYMBOLS 10 ... Susceptor, 12 ... Upper member, 14 ... Lower member, 16 ... Wafer pocket, 22 ... Fitting convex part, 22b ... Lower surface, 32 ... Fitting concave part, 40 ... Susceptor, 42 ... Upper member, 44 ... Lower side 54, fitting concave portion, 54b, bottom surface, 56, fitting convex portion, G, gap, E, outer peripheral edge, T, thickness, P, inner peripheral end

Claims (6)

A susceptor having a wafer pocket for placing a wafer,
An upper member made of high-purity silicon carbide having the wafer pocket on the upper surface side, and having a fitting convex portion projecting downward from a position on the inner peripheral side with respect to the outer peripheral portion on the lower surface side;
A lower member that supports the upper member by having a fitting concave portion in surface contact with the lower surface of the fitting convex portion on the upper surface side;
With
When the upper member is set on the lower member by inserting the fitting convex portion into the fitting concave portion, the lower member is covered over the entire surface by the upper member in plan view, and the outer periphery The susceptor is characterized in that a portion is not in contact with the lower member. A susceptor having a wafer pocket for placing a wafer,
An upper member made of high-purity silicon carbide having the wafer pocket on the upper surface side, and having a fitting recess recessed on the lower surface side from the position on the inner peripheral side than the outer peripheral portion,
A lower member for supporting the upper member by having a fitting convex portion in surface contact with the bottom surface of the fitting concave portion on the upper surface side;
With
When the upper member is set on the lower member by inserting the fitting convex portion into the fitting concave portion, the lower member is covered over the entire surface by the upper member in plan view, and the outer periphery The susceptor is characterized in that a portion is not in contact with the lower member.   The susceptor according to claim 1 or 2, wherein when the upper member is set on the lower member, a gap formed between the outer peripheral portion and the lower member is 0.1 mm or less. .   4. The susceptor according to claim 3, wherein the gap is formed from an outer peripheral edge of the upper member to an inner peripheral side of 1 mm or more.   The susceptor according to claim 4, wherein the outer peripheral portion has a thickness of 1 mm or more.   When the upper member is set on the lower member, the formation position of the wafer pocket is determined in advance so that the horizontal position of the wafer pocket is entirely on the inner peripheral side of the inner peripheral end of the gap. The susceptor according to claim 3, wherein the susceptor is provided.

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