Epitaxial growth susceptor and method for manufacturing epitaxial wafer

Abstract

The present invention is a susceptor for epitaxial growth of a wafer having a (110) main surface, the susceptor having a pocket on which the wafer is placed and an outer peripheral portion surrounding the pocket, the outer peripheral portion being provided with a flat portion and a raised portion, the raised portion being a portion adjacent to the pocket, and a pouch disposed on the upper surface of the flat portion and having a portion protruding more than the upper surface of the flat portion, and the pouch is designed such that the height of the upper surface of the wafer is higher than the height of the upper surface of the flat portion when the wafer is placed in the pouch. As a result, provided is a susceptor for epitaxial growth, with which it is possible to manufacture a (110) epitaxial wafer having high flatness using a wafer (substrate) having (110) a main surface.

Description

Technical Field

[0001] The invention relates to a susceptor for epitaxial growth and a method for manufacturing an epitaxial wafer. Background Art

[0002] With the recent miniaturization of circuit line widths of semiconductor devices, wafers for advanced devices are required to have high flatness even in the outermost peripheral region.

[0003] Up to now, epitaxial wafers with (100) as the main surface have been used, and a susceptor has been developed mainly for wafers with (100) planes as shown in Patent Document 1. However, in terms of device characteristics, large-diameter epitaxial wafers with main surfaces other than (100) planes as shown in Patent Document 2 are currently required. However, the local growth rate of the outermost peripheral area changes due to the influence of the adjacent orientation, so a susceptor design that matches the main surface is being sought.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-40534

[0007] Patent Document 2: Japanese Patent Application Publication No. 2021-34410 Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] In line with the most advanced devices, the demand for epitaxial wafers with a main surface of (110) is increasing, and high flatness is becoming increasingly important. However, the crystal plane orientation is different from that of (100) wafers, and even if a pedestal developed for (100) is used, it is still difficult to flatten multiple wafer flatness indicators such as ESFQR MAX and Front ZDD at the same time.

[0010] Patent document 1 proposes a susceptor characterized in that the concave portion (pocket) for accommodating the wafer is deeper than the thickness of the wafer and a protrusion is provided on the side wall. Generally speaking, if the side wall is set higher, it will become difficult to supply the processing gas to the outermost peripheral portion of the wafer, and the vapor phase growth will be suppressed, so that the thickness of the epitaxial film will become thinner at the periphery, and the Front ZDD, which is one of the indicators of flatness, will shift to the negative side. Here, compared with the (100) epitaxial wafer, the Front ZDD of the (110) wafer is more likely to change to the negative side, so when the above-mentioned proposed susceptor is used, the depression of the periphery will become larger, and even if the protrusion is used in conjunction with the (110) use, it is difficult to improve the Front ZDD.

[0011] Patent Document 2 particularly describes a susceptor whose main surface is a (111) plane. However, in such a case, the growth rate of the outermost portion still differs between the faster portion and the slower portion, making it difficult to flatten the ESFQR.

[0012] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a susceptor for epitaxial growth and a method for manufacturing an epitaxial wafer, which can manufacture a highly flat (110) epitaxial wafer using a wafer (substrate) whose main surface is (110).

[0013] (II) Technical solution

[0014] The present invention is made to achieve the above-mentioned purpose and provides a base for epitaxial growth, which is a base for performing epitaxial growth on a wafer whose main surface is a (110) plane, characterized in that it has a bag for mounting the wafer and a peripheral portion surrounding the bag, wherein a flat portion and a raised portion are provided in the peripheral portion, the raised portion is a portion adjacent to the bag and has a portion that protrudes more than the upper surface of the flat portion, and the bag is designed so that when the wafer is mounted in the bag, the height of the upper surface of the wafer is above the height of the upper surface of the flat portion.

[0015] According to such an epitaxial growth susceptor, a highly flat (110) epitaxial wafer can be manufactured using a wafer whose main surface is (110).

[0016] In this case, the outer peripheral portion may be provided with a recessed portion which is a portion adjacent to the bag and has a portion that is more recessed than an upper surface of the flat portion.

[0017] Thus, a (110) epitaxial wafer with high flatness can be manufactured more reliably using a wafer whose main surface is (110).

[0018] In this case, when the wafer is placed in the bag, the bag height from the position of the lower surface of the wafer to the upper surface of the flat portion may be equal to or greater than half the thickness of the wafer.

[0019] Thus, a (110) epitaxial wafer with high flatness can be manufactured more reliably using a wafer whose main surface is (110).

[0020] In this case, when the wafer is placed in the bag, a difference between a bag height from a position of a lower surface of the wafer to an upper surface of the flat portion and a thickness of the wafer may be within 0.30 mm.

[0021] Thus, a (110) epitaxial wafer with high flatness can be manufactured more reliably using a wafer whose main surface is (110).

[0022] In this case, when the wafer is placed in the bag, the bag height from the position of the lower surface of the wafer to the lower end of the recessed portion may be equal to or greater than half the thickness of the wafer.

[0023] Thus, a (110) epitaxial wafer with high flatness can be manufactured more reliably using a wafer whose main surface is (110).

[0024] At this time, when the wafer is placed in the bag, a difference between a bag height from a position of a lower surface of the wafer to a lower end of the recessed portion and a thickness of the wafer may be within 0.30 mm.

[0025] Thus, a (110) epitaxial wafer with high flatness can be manufactured more reliably using a wafer whose main surface is (110).

[0026] The present invention is made to achieve the above-mentioned purpose and provides a method for manufacturing an epitaxial wafer, which uses the above-mentioned epitaxial growth base to vapor-grow an epitaxial layer on the surface of a wafer whose main surface is a (110) plane. The manufacturing method is characterized in that it has the following steps: after the wafer is placed in a bag of the epitaxial growth base and configured so that the orientation of the {111} plane adjacent to the (110) plane of the surface of the wafer is opposite to the raised portion, vapor-growth is performed.

[0027] According to such an epitaxial wafer manufacturing method, a highly flat (110) epitaxial wafer can be manufactured using a wafer whose main surface is (110).

[0028] (III) Beneficial effects

[0029] As described above, according to the epitaxial growth susceptor of the present invention, a (110) epitaxial wafer with high flatness can be manufactured using a wafer whose main surface is (110).

[0030] According to the epitaxial wafer manufacturing method of the present invention, a highly flat (110) epitaxial wafer can be manufactured using a wafer whose main surface is (110). BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 and 2 . The epitaxial growth susceptor according to the embodiment of the present invention is shown in a plan view (a) and a cross-sectional view along the line AA (b).

[0032] Figure 2 It is a schematic diagram showing the height relationship between the susceptor and the wafer in Example 1.

[0033] Figure 3 This is a schematic diagram showing the raised portion of the base of Example 1 as viewed from the center side.

[0034] Figure 4 is a schematic diagram of a wafer for epitaxial growth, and is a schematic diagram of the case of an oriented (001) notch adjacent to the wafer surface.

[0035] Figure 5 Schematic diagram showing the height relationship between the susceptor and the wafer in Comparative Example 1.

[0036] Figure 6 This is a schematic diagram of the base of Comparative Example 1 viewed from the center side.

[0037] Figure 7 It is a schematic diagram showing the height relationship between the base and the wafer in Example 2. DETAILED DESCRIPTION

[0038] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0039] As described above, there is sought a method for manufacturing an epitaxial growth susceptor and an epitaxial wafer, which can manufacture a highly flat (110) epitaxial wafer using a wafer whose main surface is (110).

[0040] The inventors have conducted a careful study on the above-mentioned technical problem and found that a highly flat (110) epitaxial wafer can be manufactured using a wafer with a main surface of (110) by using a base for epitaxial growth, thereby completing the present invention. The base for epitaxial growth is a base for performing epitaxial growth on a wafer with a main surface of (110), and is characterized in that it has a bag for mounting the wafer and an outer peripheral portion surrounding the bag, a flat portion and a raised portion are provided in the outer peripheral portion, the raised portion is a portion adjacent to the bag and has a portion that protrudes more than the upper surface of the flat portion, and the bag is designed so that when the wafer is mounted in the bag, the height of the upper surface of the wafer is above the height of the upper surface of the flat portion.

[0041] Hereinafter, a susceptor for epitaxial growth and a method for manufacturing an epitaxial wafer according to an embodiment of the present invention will be described.

[0042] (Susceptor for epitaxial growth)

[0043] Figure 1 (a) shows a top view of an epitaxial growth susceptor according to an embodiment of the present invention. Figure 1 (b) is a cross-sectional view of a susceptor for epitaxial growth according to an embodiment of the present invention.

[0044] as Figure 1 As shown in (a) and (b) of FIG. 1 , the epitaxial growth susceptor 1 according to the embodiment of the present invention includes a bag 10 for mounting a wafer W thereon and an outer peripheral portion 12 surrounding the bag 10 .

[0045] The outer peripheral portion 12 is provided with a flat portion 14 and a raised portion 16 . The raised portion 16 is a portion adjacent to the bag 10 and has a portion protruding further than the upper surface of the flat portion 14 .

[0046] The concave bag 10 for placing the wafer W is provided with a raised portion 16 at least in a portion where the {111} plane orientation exists when the wafer W is placed.

[0047] The local growth rate of the {111} plane orientation is fast, and therefore the growth rate can be suppressed by the protruding portion.

[0048] The bag 10 is designed such that when the wafer W is placed in the bag 10 , the height of the upper surface of the wafer W is higher than the height of the upper surface of the flat portion 14 (the upper surface of the wafer W protrudes further than the flat portion 14 ).

[0049] At least a portion of the direction in which the {100} plane exists is designed so that, when the wafer W is mounted, the surface of the wafer W is higher than the side surface of the bag.

[0050] The growth rate of the {100} orientation is relatively slow, and depressions are likely to occur at the periphery, which has a stronger effect of shifting the Front ZDD to the negative side. Therefore, by setting the wafer surface to a height higher than the bag side, the displacement of the Front ZDD to the negative side caused by the peripheral depressions can be suppressed.

[0051] The epitaxial growth susceptor according to the embodiment of the present invention is provided with a bag 10 for placing the wafer W and a through hole (not shown) for installing lift pins for lifting the wafer W. The wafer W is placed on the bag 10 by lifting and lowering the lift pins through the conveying mechanism.

[0052] The bag 10 may be provided with a shape to suppress backside deposition (Japanese: デポ), a through hole to suppress autodoping, or the like.

[0053] Preferably, when the wafer W is placed in the bag 10, the bag height from the position of the lower surface of the wafer W to the upper surface of the flat portion 14 is more than half of the thickness of the wafer W. The upper limit of the bag height is not particularly limited, for example, it is less than the thickness of the wafer W. In addition, more preferably, when placed in the bag 10, the difference between the bag height from the position of the lower surface of the wafer W to the upper surface of the flat portion 14 and the thickness of the wafer W is within 0.30 mm. The lower limit of the thickness difference is not particularly limited, for example, it exceeds 0 mm. By setting such a height position relationship, the epitaxial wafer can be made into a wafer with higher flatness.

[0054] When the height of the bag side is too low, the process gas becomes prone to surround the back side of the wafer, causing the quality of the back side of the wafer to deteriorate.

[0055] Preferably, the outer peripheral portion 12 is provided with a recessed portion which is a portion adjacent to the bag 10 and has a portion recessed from the upper surface of the flat portion.

[0056] By providing a local depressed portion in the orientation corresponding to the {100} orientation of the bag 10, the growth rate of this portion is accelerated, and the displacement of the Front ZDD to the negative side can be more effectively suppressed.

[0057] Preferably, when the wafer W is placed in the bag 10, the bag height from the position of the lower surface of the wafer W to the lower end of the recessed portion is more than half of the thickness of the wafer W. The upper limit of the bag height is not particularly limited, for example, it is less than the thickness of the wafer W. In addition, more preferably, when the wafer W is placed in the bag 10, the difference between the bag height from the position of the lower surface of the wafer W to the lower end of the recessed portion and the thickness of the wafer W is within 0.30 mm. The lower limit of the thickness difference is not particularly limited, for example, it exceeds 0 mm.

[0058] When the height of the bag side is too low, the process gas becomes prone to surround the back side of the wafer, causing the quality of the back side of the wafer to deteriorate.

[0059] (Method for manufacturing epitaxial wafer)

[0060] Next, a method for manufacturing an epitaxial wafer according to an embodiment of the present invention will be described.

[0061] The epitaxial wafer manufacturing method according to the embodiment of the present invention uses the epitaxial growth susceptor 1 to vapor-phase grow an epitaxial layer on the surface of the wafer.

[0062] This epitaxial wafer manufacturing method includes the steps of placing a wafer W on the pocket 10 of the epitaxial growth susceptor 1 and arranging the wafer W so that the orientation of the {111} plane adjacent to the (110) plane of the surface of the wafer W faces the protrusion 16 , and then performing vapor phase growth.

[0063] The ridges can suppress the growth rate of the {111} orientation, and by setting the wafer surface higher than the height of the bag side, the peripheral depression caused by the slow growth rate of the {100} orientation can be suppressed, which in turn suppresses the displacement of the Front ZDD to the negative side. Therefore, a wafer with a (110) main surface can be used to manufacture a highly flat (110) epitaxial wafer.

[0064] Example

[0065] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

[0066] (Example 1)

[0067] Figure 2It is a schematic diagram showing the height relationship between the susceptor and the wafer in Example 1.

[0068] First, a base of Example 1 was prepared, which was designed so that the height of the flat portion was 0.647 mm and the maximum height of the raised portion was 0.812 mm.

[0069] Figure 3 This is a schematic diagram showing the raised portion of the base of Example 1 as viewed from the center side.

[0070] The raised portion is provided so as to become higher toward the highest imaginary position at the center in the circumferential direction, and is provided in a range of ±40° from the highest imaginary position at the center.

[0071] Figure 4 is a schematic diagram of a wafer for epitaxial growth, and is a schematic diagram of the case of an oriented (001) notch adjacent to the wafer surface.

[0072] The wafer used for epitaxial growth is set to have a main surface (110) and a thickness of 0.775±0.01 mm.

[0073] When the wafer is placed on the susceptor, the pocket portion of the flat portion becomes lower than the wafer surface, and the {111} plane orientation of the (110) wafer is arranged to face the raised portion of the susceptor.

[0074] In this manner, the susceptor of the present invention was installed in the chamber, and epitaxial growth was performed on a wafer that had been cleaned in advance and had a main surface of (110). After the sample of Example 1 was produced, the flatness was measured to evaluate the quality.

[0075] (Comparative Example 1)

[0076] Figure 5 Schematic diagram showing the height relationship between the susceptor and the wafer in Comparative Example 1.

[0077] Figure 6 This is a schematic diagram of the base of Comparative Example 1 viewed from the center side.

[0078] A susceptor of Comparative Example 1 was prepared which had no raised portion on the outer peripheral portion and was designed so that when the wafer was placed in the pocket, the pocket height in the entire circumferential direction was 0.830 mm.

[0079] The wafer to be reacted has a main surface (110) and a thickness of 0.775±0.01 mm. When the wafer is placed on a susceptor, the wafer surface is lower than the pocket portion over the entire circumference.

[0080] The susceptor was installed in a chamber, and epitaxial growth was performed on a wafer that had been cleaned in advance and had a main surface of (110). After producing a sample of Comparative Example 1, flatness measurement was performed to evaluate the quality.

[0081] The results of the quality evaluation showed that the average ESFQRMAX of the sample of Comparative Example 1 was 0.022 μm, which is an indicator of the flatness of the peripheral portion, while the sample of Example 1 was 0.018 μm, confirming an 18% improvement. In addition, the Front ZDD of the sample of Comparative Example 1 was -25.7 nm / mm. 2 In contrast, the sample of Example 1 is -14.9nm / mm 2 , and obtain about 10nm / mm 2 The effect of shifting left or right to the positive side.

[0082] (Example 2)

[0083] Figure 7 It is a schematic diagram showing the height relationship between the base and the wafer in Example 2.

[0084] First, a base of Example 2 is prepared, which is designed so that the height of the flat portion is 0.647 mm, the maximum height of the raised portion is 0.812 mm, and it also has a recessed portion, and the height of the lower end of the recessed portion is 0.497 mm.

[0085] The susceptor was installed in a growth chamber, and epitaxial growth was performed on a wafer that had been cleaned in advance and had a main surface of (110). After the sample of Example 2 was produced, flatness measurement was performed to evaluate the quality. At this time, the {111} plane orientation of the (110) wafer was placed opposite to the raised portion, and the {100} plane orientation of the (110) wafer was placed opposite to the depressed portion.

[0086] The results of the quality evaluation showed that the ESFQR MAX, which is an indicator of the flatness of the peripheral portion, was 0.016 μm for the sample of Example 2, confirming an improvement effect. In addition, the Front ZDD was -12.9 nm / mm for the sample of Example 2. 2 , to obtain the effect of displacement to the positive side.

[0087] This manual contains the following methods.

[0088] [1] A base for epitaxial growth, which is a base for performing epitaxial growth on a wafer whose main surface is a (110) plane, characterized in that it has a bag for mounting the wafer and an outer peripheral portion surrounding the bag, wherein the outer peripheral portion is provided with a flat portion and a raised portion, the raised portion being a portion adjacent to the bag and having a portion protruding further than the upper surface of the flat portion, and the bag is designed so that when the wafer is mounted in the bag, the height of the upper surface of the wafer is located above the height of the upper surface of the flat portion.

[0089] [2] The epitaxial growth susceptor described in [1] above is characterized in that a recessed portion is provided in the outer peripheral portion, the recessed portion is a portion adjacent to the bag and has a portion that is more recessed than the upper surface of the flat portion.

[0090] [3] The epitaxial growth susceptor as described in [1] or [2] above is characterized in that when the wafer is placed in the bag, the bag height from the position of the lower surface of the wafer to the upper surface of the flat portion is more than half the thickness of the wafer.

[0091] [4] A susceptor for epitaxial growth as described in any one of [1] to [3] above, characterized in that when the wafer is placed in the bag, the difference between the bag height from the position of the lower surface of the wafer to the upper surface of the flat portion and the thickness of the wafer is within 0.30 mm.

[0092] [5] The epitaxial growth susceptor as described in [2] above is characterized in that when the wafer is placed in the bag, the bag height from the position of the lower surface of the wafer to the lower end of the recessed portion is more than half the thickness of the wafer.

[0093] [6] The epitaxial growth susceptor as described in [2] above is characterized in that when the wafer is placed in the bag, the difference between the bag height from the position of the lower surface of the wafer to the lower end of the recessed portion and the thickness of the wafer is within 0.30 mm.

[0094] [7] A method for manufacturing an epitaxial wafer, which uses the epitaxial growth base described in any one of [1] to [6] above to vapor-grow an epitaxial layer on the surface of a wafer whose main surface is a (110) plane, the manufacturing method being characterized by comprising the following steps: after placing a wafer in a bag of the epitaxial growth base and configuring the wafer so that the orientation of the {111} plane adjacent to the (110) plane of the surface of the wafer is opposite to the raised portion, vapor-growth is performed.

[0095] The present invention is not limited to the above-described embodiments. The above-described embodiments are illustrative, and any scheme having substantially the same structure and achieving the same function and effect as the technical concept described in the claims of the present invention is included in the technical scope of the present invention.

Claims

1. A susceptor for epitaxial growth, which is a susceptor for epitaxial growth of a wafer whose main surface is a (110) plane, characterized in that: A bag for placing wafers and a peripheral portion surrounding the bag are provided. The outer peripheral portion is provided with a flat portion and a raised portion, the raised portion being a portion adjacent to the bag and having a portion protruding more than an upper surface of the flat portion, and The bag is designed so that when the wafer is placed in the bag, the height of the upper surface of the wafer is higher than the height of the upper surface of the flat portion.

2. The epitaxial growth susceptor according to claim 1, wherein: The outer peripheral portion is provided with a recessed portion which is a portion adjacent to the bag and has a portion that is more recessed than an upper surface of the flat portion.

3. The epitaxial growth susceptor according to claim 1, wherein: When the wafer is placed in the bag, the bag height from the position of the lower surface of the wafer to the upper surface of the flat portion is equal to or greater than half the thickness of the wafer.

4. The epitaxial growth susceptor according to claim 1, wherein: When the wafer is placed in the bag, a difference between a bag height from a position of a lower surface of the wafer to an upper surface of the flat portion and a thickness of the wafer is within 0.30 mm.

5. The epitaxial growth susceptor according to claim 2, wherein: When the wafer is placed in the bag, the bag height from the position of the lower surface of the wafer to the lower end of the recessed portion is equal to or greater than half the thickness of the wafer.

6. The epitaxial growth susceptor according to claim 2, wherein: When the wafer is placed in the bag, a difference between a bag height from a position of a lower surface of the wafer to a lower end of the recessed portion and a thickness of the wafer is within 0.30 mm.

7. A method for manufacturing an epitaxial wafer, using the epitaxial growth susceptor according to claim 1, to vapor-grow an epitaxial layer on a wafer surface whose main surface is a (110) plane, the method comprising the following steps: After placing a wafer in the pocket of the epitaxial growth susceptor and arranging the wafer so that the orientation of the {111} plane adjacent to the (110) plane on the surface of the wafer faces the protrusion, vapor phase growth is performed.

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