JP2012234924A - Manufacturing method of semiconductor epi wafer and gallium arsenic substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor epi wafer which eliminates non growth regions of semiconductor crystals and reduces the inhibition of the material supply to a substrate when the substrate is held in a face down manner and the semiconductor crystals are grown with Metal Organic Vapor Phase Epitaxy (MOVPE).SOLUTION: In a manufacturing method of a semiconductor epi wafer, a material gas is supplied to a heated substrate 11 to grow semiconductor crystals on the substrate 11. In the manufacturing method, the substrate 11 has chamfered parts 15 at peripheral parts 14 on the side of a growth surface 12 where the semiconductor crystals are grown, is arranged in a face down manner, and is held only at the chamfered parts 15. The semiconductor crystals are grown with the grow surface 12 of the substrate 11 facing downward.

Description

  The present invention relates to a method for manufacturing a semiconductor epi-wafer and a gallium arsenide substrate in which a semiconductor crystal is grown face-down in metal organic vapor phase epitaxy.

  MOVPE (Metal-Organic Vapor Phase Epitaxy) is a crystal growth method using an organic metal or gas as a raw material.

  This method is used to grow compound semiconductor crystals, and the film thickness can be controlled on the atomic layer order. Therefore, it is necessary to control the film thickness of several nanometers such as nanotechnology such as semiconductor laser diodes and light emitting diodes. Used in the field.

  Compared to MBE (Molecular Beam Epitaxy), which is a typical semiconductor crystal growth device, there is less in-plane film thickness deviation, high-speed growth is possible, and no ultra-high vacuum is required. Therefore, it is easy to increase the size of the apparatus, and as a crystal growth apparatus for mass production, it is widely used for crystal growth of optical devices such as semiconductor laser diodes and light emitting diodes and electronic devices such as power amplifiers.

  FIG. 5 shows an MOVPE apparatus 50 for producing a compound semiconductor crystal on a substrate by MOVPE.

  MOVPE is a TMI (Tri-Methyl-Indium) source material for group III elements In (indium), a TMG (Tri-Methyl-Gallium) source material for Al (aluminum), and a Ga (gallium) source material. An organometallic raw material 51 such as TMA (Tri-Methyl-Aluminum) is used as the raw material.

The group V source gas 52 includes AsH ₃ (arsine) which is a hydride of As (arsenic), PH ₃ (phosphine) which is a hydride of P (phosphorus), and NH ₃ which is a hydride of N (nitrogen). Use special high-pressure gas such as ammonia.

Although the organometallic raw material 51 is liquid or solid at normal temperature, it is bubbled using H ₂ or N ₂ as the carrier gas 53 in the raw material kept at a constant temperature in a thermostatic bath using the property of high saturated vapor pressure. Thus, a sufficient amount of growth raw material for crystal growth can be supplied to the growth substrate at a stable gas flow rate.

  When the source gas in which the organometallic source 51, the group V source gas 52, and the carrier gas 53 are mixed is ejected from the injector 54 and reaches the substrate (gallium arsenide substrate) 56 heated by the heater 55, decomposition and chemistry occur. A semiconductor crystal grows by reacting and taking over crystal information. Semiconductors with various compositions, physical properties, and structures can be made by changing the flow rate ratio, temperature, and pressure of the source gas.

  As shown in FIG. 6, chamfered portions 58 for preventing cracks and chips due to slight impacts during the polishing process and conveyance are provided at the peripheral portions 57 on both surfaces of the substrate 56, for example, with a taper angle of 15 °. The length is 120 to 180 μm.

  When such a substrate 56 is set on the susceptor 61 of the disk 60 together with the soaking plate 59, the direction of the surface of the substrate 56 is the case where the front surface (growth surface 62) is grown up (face up), There is a case of growing up face down (face down).

  In the case of growing face down, in the prior art, a claw portion 63 provided on the susceptor 61 is used to support the substrate 56 and prevent the substrate 56 from falling, and as shown in FIGS. The end face of the substrate 56 is designed to be hooked and supported by several (three in FIG. 7) claw portions 63 so that the growth surface 62 is hooked on the claw portion 63 at the end surface (peripheral portion 57).

JP 2007-42899 A JP 2007-266043 A

  In the prior art, the claw portion 63 used to support the substrate 56 is placed on the front surface, which is the growth surface 62 of the substrate, as shown in FIG. 6, so that the front surface applied to the claw portion 63 is not grown. There is a problem that becomes an area.

  In addition, the supply of the raw material is hindered even on the growth surface 62 around 1 to 5 mm around the claw portion 63, which causes the in-plane distribution (thickness distribution, etc.) of the semiconductor crystal to deteriorate, particularly in the 4-inch size. This is a problem when the above substrate 56 is used.

  The present invention has been made to solve the above-described problems. When a semiconductor crystal is grown by MOVPE while holding the substrate face-down, an ungrown region of the semiconductor crystal is eliminated and the supply of the raw material to the substrate is inhibited. The purpose is to reduce.

  In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor epi-wafer by supplying a source gas on a heated substrate and growing a semiconductor crystal on the substrate, wherein the substrate is grown by growing the semiconductor crystal. This is a method in which a chamfered portion is provided on the peripheral edge of the surface side, the face is down, and only the chamfered portion is held, and the semiconductor crystal is grown with the growth surface of the substrate facing downward. .

  The substrate has the chamfered portion formed by taper processing only at the peripheral portion on the growth surface side, the taper angle of the chamfered portion is 13 ° to 17 °, and the taper length is 900 μm to 1400 μm. Good to be.

  It is preferable that the entire circumference of the chamfered portion is held by a claw portion provided on the susceptor.

  Further, the present invention is a gallium arsenide substrate having a chamfered portion formed by taper processing only at a peripheral portion on a growth surface side on which a semiconductor crystal is grown.

  The gallium arsenide substrate may have a circular shape with a size of 4 inches or more, a taper angle of the chamfered portion of 13 ° to 17 °, and a taper length of 900 μm to 1400 μm.

  According to the present invention, when a semiconductor crystal is grown by MOVPE while holding the substrate face-down, an ungrown region of the semiconductor crystal can be eliminated and the inhibition of the supply of the raw material to the substrate can be reduced.

It is a fragmentary sectional view showing one embodiment of the present invention. It is a fragmentary sectional view which shows the example of a dimension of the gallium arsenide board | substrate which concerns on one embodiment of this invention. It is a fragmentary sectional view which shows the example of a dimension of the gallium arsenide board | substrate which concerns on one embodiment of this invention. It is a bottom view which shows one embodiment of this invention. It is a schematic sectional drawing explaining the manufacturing method of the semiconductor epiwafer by MOVPE. It is a fragmentary sectional view explaining the holding method of the conventional board | substrate. It is a bottom view explaining the conventional holding | maintenance method of a board | substrate.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a partial cross-sectional view showing the present embodiment, and is a diagram for explaining a method of holding a substrate face down by a susceptor of an MOVPE apparatus.

  As shown in FIG. 1, in the method for manufacturing a semiconductor epiwafer according to the present embodiment, a substrate 11 for crystal growth of a compound semiconductor is placed face down with a growth surface 12 on which a semiconductor crystal is grown facing downward. It is held by the claw portion 13 provided at 61. A soaking plate 59 is disposed above the substrate 11.

  The substrate 11 is a gallium arsenide substrate having a circular shape with a thickness of 450 μm and 4 inches, and a substrate having an orientation flat formed on a part of the peripheral edge portion 14 is used. In the present invention, a gallium arsenide substrate having a size of 4 inches or more can also be used.

  Further, the substrate 11 has a chamfered portion 15 formed by taper processing only at the peripheral edge portion 14 on the growth surface 12 side, and the claw portion 13 provided on the susceptor 61 holds only the chamfered portion 15. (That is, only the chamfered portion 15 is clawed) so that the semiconductor crystal is grown with the growth surface 12 facing downward. In the present invention, it is possible to use a substrate on which the surface opposite to the growth surface 12 (back surface) is tapered, but in the substrate 11 in which the chamfered portion 15 is formed only on the growth surface 12 side. It is preferable because the occurrence of chipping / cracking at the peripheral portion 14 can be reduced in the back lapping (back surface polishing) step after the semiconductor crystal is grown.

  2 and 3 show examples of the shape and dimensions of the chamfered portion 15 formed on the peripheral edge portion 14 of the substrate 11 by taper processing. In the present embodiment, as shown in FIG. 2, a surface of the substrate 11 having a taper length of 1000 μm, a taper height of 225 μm, and a taper angle of about 12.68 ° with respect to a substrate 11 having a thickness of 450 μm. A catch portion 15 is formed. However, more preferably, for example, as shown in FIG. 3, the chamfered portion 15 may be formed within a taper length of 900 μm to 1400 μm and a taper angle of 13 ° to 17 °. By doing so, it is possible to prevent the substrate 11 from falling even if the variation in the diameter of the substrate 11 is assumed to be ± 0.3 mm and the accuracy of machining of the claw portion 13 is assumed to be ± 0.5 mm. .

  A substrate 11 (gallium arsenide substrate) that satisfies the above conditions is suitable for use in the epiwafer manufacturing method of the present invention.

  In the present embodiment, as shown in FIG. 4, the shape of the claw portion 13 that holds the chamfered portion 15 does not hang on the front surface (growth surface 12) of the substrate 11 and does not drop the substrate 11. Make it as small as possible (thinner). On the other hand, in order to compensate for the strength that is reduced by reducing the thickness, the shape of the outer periphery of the substrate 11 is adjusted so that the entire periphery of the substrate 11 can be maintained.

  Such a substrate 11 is held by the claw portion 13 of the susceptor 61 and set in the MOVPE apparatus 50 as shown in FIG. 5, and the substrate 11 is heated by the heater 55 via the heat equalizing plate 59, and the organometallic raw material By supplying the source gas 51 and the group V source gas 52 and the carrier gas 53, the source gas is decomposed and chemically reacted on the substrate to grow a semiconductor crystal, and a semiconductor epi-wafer is manufactured.

  As described above, in the present invention, when a semiconductor epi-wafer is manufactured by MOVPE, a substrate in which a chamfered portion is formed at the peripheral portion on the growth surface side on which a semiconductor crystal is grown is used, face-down and only the chamfered portion. The semiconductor crystal is grown with the growth surface of the substrate facing downward.

  By doing so, it is possible to eliminate the portion which has become an ungrown region due to the claw portion of the susceptor in the conventional method, and to grow the semiconductor crystal over the entire growth surface of the substrate. In addition, since the growth surface of the substrate is positioned on the lower side, it is possible to suppress the supply of the source gas from being hindered by the claw portion.

  Furthermore, when the claw portion of the susceptor is shaped so as to hold the entire circumference of the chamfered portion of the substrate, the claw portion can be made as small as possible (thinner) while maintaining the strength of the claw portion. Inhibition of raw material supply can be further suppressed.

  Furthermore, when the chamfered portion is formed only on the growth surface side of the substrate, the end surface becomes dull and thick as compared with the conventional substrate in which the chamfered portion is formed on both sides. It is also possible to reduce chipping / cracking that is likely to occur at a sharp end face in the back surface polishing step (back wrap step) of the substrate.

  It goes without saying that the present invention is not limited to the above embodiment, and various modifications can be made.

11 Substrate 12 Growth surface 14 Edge 15 Chamfer

Claims (5)

In a method for manufacturing a semiconductor epi-wafer by supplying a source gas onto a heated substrate and growing a semiconductor crystal on the substrate,
The substrate has a chamfered portion at the peripheral portion on the growth surface side on which the semiconductor crystal is grown, face-down, and only the chamfered portion is held,
The method of manufacturing a semiconductor epi-wafer, wherein the semiconductor crystal is grown with a growth surface of the substrate facing downward.   The substrate has the chamfered portion formed by taper processing only at the peripheral portion on the growth surface side, the taper angle of the chamfered portion is 13 ° to 17 °, and the taper length is 900 μm to 1400 μm. The method for producing a semiconductor epi-wafer according to claim 1.   3. The method of manufacturing a semiconductor epi-wafer according to claim 1, wherein the entire periphery of the chamfered portion is held by a claw portion provided on the susceptor.   A gallium arsenide substrate comprising a chamfered portion formed by taper processing only at a peripheral portion on a growth surface side on which a semiconductor crystal is grown.   5. The gallium arsenide substrate according to claim 4, wherein the gallium arsenide substrate has a circular shape with a size of 4 inches or more, a taper angle of the chamfered portion of 13 ° to 17 °, and a taper length of 900 μm to 1400 μm.