JP2006186105A - Epitaxial growth device and susceptor used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a susceptor for an epitaxial growth device which can reduce a thermal stress applied locally to a wafer and has less fault occurring in the wafer. <P>SOLUTION: The susceptor used for the epitaxial growth device 1 is provided with a recessed part 15 enough to place a wafer 14 with an orientation flat 16. In the epitaxial growth device 1, the plane shape of the recessed part 15 and that of the wafer 14 are homothetical to each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an epitaxial growth apparatus and a susceptor used therefor.

  Conventionally, when manufacturing a wafer, a technique for growing an epitaxial layer on the wafer by a vapor phase growth method (epitaxial growth method) is known in order to reduce micro defects on the wafer surface.

  The growth of the epitaxial layer is generally performed using, for example, a pancake type epitaxial growth apparatus. Specifically, the growth of the epitaxial layer is performed by placing the wafer on a susceptor in the epitaxial growth apparatus and heating the wafer.

As the susceptor, a susceptor 49 is shown in FIG. The susceptor 49 is formed of a circular flat plate as shown in FIG. The susceptor 49 is provided with a plurality of circular pocket portions 50 arranged concentrically at appropriate intervals. As shown in FIG. 6, an epitaxial layer grows on the wafer 51 by placing the wafer 51 in the pocket portion 50 and supplying the reaction gas to the wafer 51 and heating the wafer 51.
SMSze “Semicondutor Dvices Physics and Tecnology 2nd Edition” published by John Wiley & Sons, Inc 2002 Toshiba Ceramic Co., Ltd., special carbon and high purity graphite products, [Search on December 24, 2004], Internet <URL: http://tocera.co.jp/en/products/semidon/carbon.html>

  The planar shape of the pocket portion 50 is circular as shown in FIGS. On the other hand, the wafer 51 put in the pocket portion 50 has a linear notch (orientation flat portion; orientation flat portion) 52 in order to indicate the surface orientation of the wafer 51 and the like, as shown in FIG. Yes. That is, the planar shape of the wafer 51 is non-circular.

  As described above, when an epitaxial layer is grown on the wafer 51, the wafer 51 needs to be put in the pocket portion 50 and heated. However, since the wafer 51 has the orientation flat portion 52, how heat is transmitted from the pocket portion 50 varies depending on the position of the outer peripheral portion of the wafer 51. Specifically, as shown in FIG. 6, the way in which heat is transmitted differs between the boundary region P · Q between the orientation flat portion 52 and the curved surface portion 54 in the wafer 51 and the region other than the boundary region P · Q.

  More specifically, the boundary regions P and Q are subjected to a larger thermal stress than regions other than the boundary regions P and Q. Therefore, as shown in FIG. That is, a large number of linear crystal defects occur in the epitaxial layer on the wafer 51.

  For this reason, the element formed in the boundary region P / Q in which the crystal defect has occurred becomes an element defect and a characteristic defect, and thus has to be removed. When the elements are removed, the number of chips that can be taken in the wafer 51 is lowered, which causes a problem that the yield is lowered.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to make the way of heat transfer to the wafer uniform, reduce local thermal stress on the wafer, and generate crystals on the wafer. An object is to provide a susceptor for an epitaxial growth apparatus with very few defects.

  In order to solve the above problems, the susceptor for an epitaxial growth apparatus of the present invention is a susceptor for an epitaxial growth apparatus provided with a recess on which a wafer having an orientation flat portion can be placed, and the planar shape of the recess and the planar shape of the wafer Are characterized by having similar shapes to each other.

  Conventionally, the planar shapes of the susceptor and the wafer are different from each other. In other words, the wafer has an orientation flat portion that is a linear notch, while the concave portion of the susceptor is not provided with a configuration corresponding to the orientation flat portion. Therefore, when a wafer having an orientation flat part is placed in the recess of the susceptor and the wafer is heated, heat is transferred between the boundary area between the orientation flat part and the other part of the outer peripheral part of the wafer and other areas. Are different from each other. More specifically, greater thermal stress is applied in the boundary region than in regions other than the boundary region. Therefore, there is a problem that many crystal defects occur in the boundary region of the wafer.

  On the other hand, according to the above configuration, the planar shape of the wafer and the planar shape of the recess provided in the susceptor are similar to each other. Therefore, the wafer can be placed in the recess so that the planar shape of the recess and the planar shape of the wafer correspond to each other. When the wafer is placed in the recess as described above, the way in which heat is applied from the recess to the outer periphery of the wafer when the wafer is heated can be made substantially uniform. That is, a large thermal stress is not applied to any region, that is, locally, as in the past. Therefore, slip lines generated in the epitaxial layer on the wafer, that is, crystal defects following the linear shape can be greatly reduced. Therefore, the number of chips that can be taken in the wafer can be increased, and the yield can be improved.

  Moreover, in the susceptor for epitaxial growth apparatuses of this invention, it is preferable that the plane part of the said recessed part which has a shape corresponding to the said orientation flat part is located in the outer edge side of the said susceptor.

  As described above, the planar shape of the wafer and the planar shape of the recess are similar to each other. Therefore, the concave portion has a portion (planar portion) having a shape corresponding to the orientation flat portion of the wafer in the planar shape.

  The wafer is taken into and out of the concave portion from the orientation flat portion of the wafer, that is, the flat portion of the concave portion. According to the above configuration, since the flat portion of the concave portion is located on the outer edge side of the susceptor, the wafer can be easily put into and out of the concave portion.

  The epitaxial growth apparatus of the present invention preferably includes any one of the above susceptors.

  As described above, the susceptor for an epitaxial growth apparatus according to the present invention has the planar shape of the recess and the planar shape of the wafer similar to each other. For this reason, the way in which heat is transferred to the wafer can be made substantially uniform, local thermal stress on the wafer can be reduced, and crystal defects generated in the wafer can be greatly reduced. Therefore, there is an effect that the number of chips taken in the wafer can be increased and the yield can be improved.

[Embodiment 1]
One embodiment of the present invention will be described with reference to FIGS. 1 to 4 as follows.

FIG. 2 is a cross-sectional view of the epitaxial growth apparatus of the present embodiment. This epitaxial growth apparatus is an apparatus for heating to a temperature necessary for growing an epitaxial layer on a wafer for a Zener diode, for example. Further, the epitaxial growth apparatus of the present embodiment is a so-called pancake type apparatus. In addition, the inch size of a wafer on which an epitaxial layer is grown using the epitaxial growth apparatus of the present embodiment is, for example, 5 inches or 6 inches. However, the epitaxial growth apparatus of this embodiment does not prevent application to a wafer size of 4 inches or less. In addition, although the structure of the epitaxial growth apparatus of this Embodiment is demonstrated below, it is not necessarily limited to this structure.
[Configuration of epitaxial growth equipment]
As shown in FIG. 1, the epitaxial growth apparatus 1 includes a base plate 2 as a base, a quartz bell jar 4, a metal bell jar 5, a reflecting plate 6, a gas nozzle 7, a high frequency induction coil (hereinafter referred to as a coil) 8, and a coil cover 9. And a disk-shaped susceptor 10 for mounting a plurality of wafers 14, a susceptor support 11 for supporting the susceptor 10, a susceptor rotating unit 12, and a nozzle rotating unit 13. The susceptor 10 has a characteristic configuration according to the present invention, which will be described later.

  The quartz bell jar 4 has a bell shape and forms an airtight reaction chamber 3 on the base plate 2. Further, the metal bell jar 5 has the same bell shape and reinforces the outside of the quartz bell jar 4.

  The reflection plate 6 is disposed in a part between the metal bell jar 5 and the quartz bell jar 4 and has a function of returning the radiant energy emitted by the susceptor 10 to the surface of the wafer 14. Thereby, energy saving can be achieved, temperature difference between the front and back of the wafer 14 can be reduced, and crystal defects can be reduced.

  The gas nozzle 7 passes through the center of each of the susceptor 10, the susceptor support part 11, and the susceptor rotation part 12, is connected to the nozzle rotation part 13, and is driven to rotate by the nozzle rotation part 13. It is like that. Further, the gas nozzle 7 has a plurality of ejection holes 7 a for ejecting a reaction gas such as monosilane in the reaction chamber 3 in the horizontal direction. The reaction gas ejected into the reaction chamber 3 in this manner is supplied radially to the upper space of the wafer 14 placed on the susceptor 10.

  Further, the coil 8 has a role as a heating source for heating the susceptor 10. The coil cover 9 is disposed between the susceptor 10 and the coil 8 so as to cover the coil 8, and has a role of isolating the coil 8 from the reaction gas.

The susceptor rotating part 12 rotates the susceptor 10 together with the susceptor support part 11 by rotating itself. An exhaust path (not shown) is provided between the base plate 2 and the quartz bell jar 4. Thereby, the reaction gas etc. in the reaction chamber 3 can be exhausted.
[Operation of epitaxial growth system]
Next, the operation of the epitaxial growth apparatus 1 will be described.

  First, the wafer 14 is placed on the susceptor 10. At this time, the surface of the wafer 14 which is the base of the epitaxial growth is in an exposed state. Then, a high frequency current is applied to the coil 8 to cause an induced current to flow through the susceptor 10 to heat the susceptor 10. When the susceptor 10 is heated, the wafer 14 is heated to a high temperature in response to the heat. At this time, the susceptor 10 is rotated by the susceptor rotating unit 12 and a reactive gas such as monosilane is ejected from the ejection hole 7 a of the gas nozzle 7.

The reaction gas is deposited on the surface of the wafer 14 through a gas phase reaction such as thermal decomposition, whereby an epitaxial layer is formed. Note that the thickness and electrical resistivity of the epitaxial layer are controlled in a process according to the applied device. For example, the thickness of the epitaxial layer is controlled by the growth rate and growth time, while the electrical resistivity of the epitaxial layer is controlled by the amount of dopant (n-type impurity or p-type impurity) implanted. As the dopant, for example, phosphorus or arsenic can be used for growing an n-type epitaxial layer, while boron or the like can be used for a p-type epitaxial layer.
[Configuration of susceptor]
Next, the susceptor 10 which is the most important part of the present invention will be described.

  As shown in FIG. 3, the susceptor 10 is a disk-shaped flat plate and has a plurality of recesses (wafer pockets) 15 on the surface. The susceptor 10 has a plurality of wafer pockets 15 as described above, and a plurality of wafers 14 can be placed on one susceptor 10. In addition, by making the shape of the susceptor 10 into a disk shape, the gas flow in the reactor (quartz bell jar) of the epitaxial apparatus 1 can be made uniform, and the epitaxial layer can be grown uniformly on the wafer 14. be able to.

  Further, the number and arrangement of the wafer pockets 15 on the susceptor 10 in FIG. 3 is merely an example, and the present invention is not limited to this. Needless to say, it is not always necessary to place the wafers 14 in all the wafer pockets 15. Furthermore, the size of the wafer 14 relative to the size of the wafer pocket 15 is merely an example, and is not limited thereto.

As described above, when an epitaxial layer is grown on the wafer 14, it is necessary to place the wafer 14 on the susceptor 10 and rotate the susceptor 10. At this time, by providing the wafer pocket 15 in the susceptor 10, the wafer 14 falls from the susceptor 10 or the wafers 14 collide even when the susceptor 10 is rotated with the wafer 14 in the wafer pocket 15. Can be prevented.
[Planar configuration of wafer pocket]
As shown in FIGS. 1A and 1B, the wafer 14 placed in the wafer pocket 15 has a linear notch called an orientation flat portion (hereinafter referred to as an orientation flat portion) 16.

  The orientation flat portion 16 has a function as a mark for indicating the surface orientation and the like of the wafer 14. On the other hand, when the epitaxial layer is grown by putting the wafer 14 in the wafer pocket 15, it is necessary to heat the wafer 14 to a high temperature as described above.

  As shown in FIG. 1B, the wafer pocket 15 of the present embodiment has a flat plane portion 17 on the inner wall 19 thereof. Further, it should be noted that the planar shape of the wafer pocket 15 is similar to the planar shape of the wafer 14 as shown in FIGS.

  Thus, when the epitaxial layer is grown on the wafer 14 by making the planar shape of the wafer pocket 15 similar to the planar shape of the wafer 14, the outer peripheral portion of the wafer 14 from the inner wall 19 of the wafer pocket 15. It is possible to make the way of heat transfer with respect to 20 almost uniform in any part of the outer peripheral portion 20 of the wafer 14.

  Specifically, boundary regions A and B between the linear orientation flat portion 16 and the curved curved surface portion 21 on the outer peripheral portion 20 of the wafer 14, and regions other than the boundary regions A and B on the outer peripheral portion 20 of the wafer 14 The heat can be transmitted uniformly. Therefore, local thermal stress applied to the wafer 14 can be reduced.

Therefore, even when high-temperature heat is transmitted from the wafer pocket 15 to the wafer 14, the occurrence of slip lines during epitaxial layer growth, that is, the generation of crystal defects following a linear shape can be greatly reduced. Therefore, since the number of chips that can be taken from the wafer 14 can be increased, the yield can be improved.
[Cross sectional configuration of wafer pocket]
Further, as shown in FIG. 1C, the wafer pocket 15 may have a curved surface portion (also referred to as R) 18 on the bottom surface. As shown in the figure, the curved surface portion 18 has a shape that swells downward from the outer periphery toward the center, in other words, the depth of the wafer pocket 15 gradually increases.

  By providing the curved surface portion 18 on the bottom surface of the wafer pocket 15, when the epitaxial layer is grown on the wafer 14, the wafer 14 is warped, the epitaxial layer on the wafer 14 is uneven, or the epitaxial layer on the wafer 14 is epitaxially grown. It is possible to prevent the uniformity of the film (layer) thickness of the layers from being deteriorated. In addition, the shape of the curved surface portion 18 is not particularly limited as long as the function of preventing such harmful effects is not impaired. Further, the depth d of the wafer pocket 15 is about 500 μm, but this value is merely an example.

  Moreover, it is preferable that the said plane part 17 is attached to the outer peripheral side (outer edge side) of the susceptor 10, as shown in FIG. In other words, when the wafer 14 is placed in the wafer pocket 15 so that the planar shape of the wafer pocket 15 and the planar shape of the wafer 14 correspond to each other as shown in the figure, the orientation flat portion 16 of the wafer 14 becomes the susceptor. 10 is preferably located on the outer peripheral side. FIG. 3 shows a state in which the planar portion 17 is provided so as to have a positional relationship orthogonal to the radial direction of the susceptor 10.

  For example, vacuum tweezers (not shown) are used when the wafer 14 is taken in and out of the wafer pocket 15. Specifically, for example, when the wafer 14 is taken out from the wafer pocket 15, the vacuum tweezers are inserted into the lower surface of the wafer 14, and the wafer 14 is sucked into the vacuum tweezers in a vacuum state and taken out. At this time, the vacuum tweezers are inserted into the lower surface of the wafer 14 from the orientation flat portion 16 side of the wafer 14. That is, the wafer 14 is put in and out by inserting vacuum tweezers from the flat surface portion 17 side of the wafer pocket 15.

Accordingly, as described above, by attaching the flat portion 17 to the outer peripheral side of the susceptor 10, the wafer 14 can be easily put in and out of the wafer pocket 15. Further, by attaching the flat portion 17 to the outer periphery of the susceptor 10, it is not necessary for the operator to poke the head into the epitaxial growth apparatus (FIG. 2) when the wafer 14 is taken in and out of the wafer pocket 15, thereby ensuring the safety of the operator. can do.
[Embodiment 2]
In the first embodiment, the case where one orientation flat portion 16 is provided on the wafer 14 has been described. However, the present invention is not limited to this, and two or more orientation flat portions 16 may be provided on one wafer 14. In this embodiment, in order to explain the difference from the first embodiment, for the sake of convenience of explanation, members having the same functions as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Is omitted.

  As shown in FIG. 4, the wafer 22 may have two orientation flat portions 23, 24, a first orientation flat portion 23 and a second orientation flat portion 24 adjacent to the first orientation flat portion 23. In this case, the wafer pocket 25 into which the wafer 22 is placed has a first plane portion 26 and a second plane portion 27 adjacent to the first plane portion 26 as shown in FIG. In addition, the planar shape of the wafer 22 and the planar shape of the wafer pocket 25 are similar to each other.

  As described above, by providing the two orientation flat portions of the first orientation flat portion 23 and the second orientation flat portion 24, for example, the position of the wafer 22 is determined by the first orientation flat portion 23, while the surface orientation is determined by the second orientation flat portion 24. And / or conductivity type may be indicated.

  In the above description, the configuration in which the first orientation flat portion 23 and the second orientation flat portion 24 of the wafer 22 are adjacent to each other has been described. However, the configuration is not limited thereto, and the two orientation flat portions may be separated from each other.

  In this way, even when the first orientation flat portion 23 and the second orientation flat portion 24 have two or more orientation flat portions, the wafer pocket 25 having a planar shape similar to the planar shape of the wafer 22 is provided. By inserting the wafer 22 into the wafer pocket 25, the way of heat transfer to the outer peripheral portion of the wafer 22 can be made uniform as described above. Therefore, it is possible to reduce the thermal stress locally applied to the wafer 22 and to greatly reduce the occurrence of slip lines. Therefore, since the number of chips taken from the wafer 22 can be increased, the yield can be improved.

  Further, by adopting the above-described configuration, it is possible to reduce the occurrence of slip lines generated in the boundary region between the first orientation flat portion 23 and the second orientation flat portion 24.

  Also in the present embodiment, it is preferable that the first flat portion 26 in the wafer pocket 25 is attached to the outer peripheral portion (outer edge portion) of the susceptor 10.

  The shape from above of the wafer pockets 15 and 25 and the shape of the cross section are collectively called a counterbore shape. As described above, the epitaxial growth apparatus 1 of the present embodiment is a traditional pancake type, but is not limited to the pancake type, and may be, for example, a barrel type or a single wafer type epitaxial growth apparatus.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. Embodiments are also included in the technical scope of the present invention.

  The susceptor of the present invention can be used for a pancake type epitaxial growth apparatus, and can be particularly suitably used for producing a Zener diode wafer. Furthermore, it can be used for the production of a wafer used for the production of semiconductor devices.

(A) is a top view which shows the shape of the wafer pocket of the 1st Embodiment of this invention, (b) is a perspective view which shows the wafer pocket shown to (a), (c), It is a longitudinal cross-sectional view which shows the wafer pocket shown to (a). It is sectional drawing which shows the pancake type epitaxial growth apparatus of the 1st and 2nd embodiment of this invention. It is a top view which shows the susceptor of the 1st Embodiment of this invention. It is a top view which shows the wafer pocket which put the wafer which has two orientation flat parts in 2nd Embodiment. It is a top view which shows the conventional susceptor. It is a top view which shows the shape of the conventional wafer pocket.

Explanation of symbols

1 Epitaxial Growth Equipment 10 Susceptor 14 Wafer 15 Wafer Pocket (Recess)
16 Orientation flat part (orientation flat part)
17 plane part 23 1st orientation flat part (orientation flat part)
24 2nd orientation flat part (orientation flat part)
25 Wafer pocket (recess)

Claims (3)

In the susceptor for an epitaxial growth apparatus provided with a recess capable of mounting a wafer having an orientation flat part,
A susceptor for an epitaxial growth apparatus, wherein the planar shape of the recess and the planar shape of the wafer are similar to each other.   The susceptor for an epitaxial growth apparatus according to claim 1, wherein the flat portion of the concave portion having a shape corresponding to the orientation flat portion is located on the outer edge side of the susceptor.   An epitaxial growth apparatus comprising the susceptor according to claim 1.

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