JP2024053476A - Semiconductor wafer manufacturing equipment - Google Patents

Abstract

The present invention aims to suppress the occurrence of epicrowns.
[Solution] The present invention includes a cylindrical growth vessel 100 into which a reaction gas is introduced and into which an epitaxial layer 11 is grown in a hollow portion 101a constituting a reaction chamber, a wafer heating susceptor 130 that is disposed in the hollow portion 100a of the growth vessel 100 and has a seed substrate 10 on one surface 130a on which the epitaxial layer 11 is grown, and supply pipes 210-230 that are provided on the growth vessel 100 and supply a reaction gas for growing an epitaxial layer to the growth vessel 100 along a normal direction to the one surface 130a. The wafer heating susceptor 130 is configured so that a dilution gas for diluting the reaction gas is supplied to the growth vessel 100 from around a portion of the one surface 130a on which the seed substrate 10 is disposed.
[Selected Figure] Figure 1

Description

The present invention relates to a semiconductor wafer manufacturing device that grows an epitaxial layer on a seed substrate to produce a semiconductor wafer.

Conventionally, semiconductor wafer manufacturing apparatuses have been proposed that manufacture semiconductor wafers by growing an epitaxial layer on a seed substrate in a reaction chamber into which a reaction gas is introduced (see, for example, Patent Document 1).

Specifically, in this semiconductor wafer manufacturing device, a recess is formed in the pedestal and the seed substrate is placed in this recess. This makes it difficult for the reaction gas to get around the outer periphery of the seed substrate, and prevents the occurrence of an epicrown, a condition in which the epitaxial layer rises on the outer periphery of the seed substrate.

JP 2019-7045 A

However, this configuration requires strict control of the depth of the recess, for example by making the depth of the recess thicker than the thickness of the seed substrate. Furthermore, the inventors' studies have confirmed that this structure may not be able to sufficiently suppress epicrowns.

In view of the above, the present invention aims to provide a semiconductor wafer manufacturing device that can suppress the occurrence of epicrowns.

In claim 1 to achieve the above object, a semiconductor wafer manufacturing apparatus is provided, which comprises a cylindrical growth vessel (100) into which a reaction gas is introduced and into which an epitaxial layer (11) is grown in a hollow portion (101a) constituting a reaction chamber, a wafer heating susceptor (130) disposed in the hollow portion of the growth vessel and having a seed substrate (10) on one surface (130a) on which an epitaxial layer is grown, and a supply pipe (210-230) provided in the growth vessel for supplying a reaction gas for growing an epitaxial layer to the growth vessel along a normal direction to the one surface, and the wafer heating susceptor is configured to supply a dilution gas for diluting the reaction gas to the growth vessel from around the portion of the one surface (130a) where the seed substrate is disposed.

With this, when growing an epitaxial layer on a seed substrate, the reaction gas supplied onto the outer edge of the seed substrate is diluted with the dilution gas, so that the epitaxial layer can be prevented from growing too fast on the outer edge of the seed substrate. This makes it possible to prevent the occurrence of an epicrown, and improve the in-plane uniformity of the epitaxial layer.

The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below.

1 is a schematic cross-sectional view showing a semiconductor wafer manufacturing apparatus according to a first embodiment. FIG. 2 is a schematic diagram of the vicinity of a seed substrate when an epitaxial layer is grown. FIG. 11 is a schematic cross-sectional view showing a semiconductor wafer manufacturing apparatus according to a second embodiment.

The following describes embodiments of the present invention with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals.

First Embodiment
A first embodiment will be described with reference to the drawings. In this embodiment, a GaN wafer manufacturing apparatus (hereinafter, also simply referred to as a manufacturing apparatus) 1 will be described as a semiconductor wafer manufacturing apparatus that grows an epitaxial layer 11 made of gallium nitride (hereinafter, also simply referred to as GaN) on a seed substrate 10 to manufacture a GaN wafer 12.

As shown in FIG. 1, the manufacturing apparatus 1 includes a growth vessel 100, a raw material supply chamber 110, a rotation device 120, a rotation displacement mechanism 160, a heating device 170, and the like. The manufacturing apparatus 1 also includes first to fifth supply pipes 210 to 250 that supply various gases to the growth vessel 100 for growing an epitaxial layer 11 made of GaN.

The growth vessel 100 has a cylindrical tube portion 101 with a hollow portion 101a that constitutes a reaction chamber, and a first lid portion 102 and a second lid portion 103 that are provided on the tube portion 101 and close the hollow portion 101a. The tube portion 101 is made of quartz glass, boron nitride, or the like, and is cylindrical in this embodiment. The first lid portion 102 and the second lid portion 103 are made of SUS or the like, and the first lid portion 102 is provided at the top end of the tube portion 101, and the second lid portion 103 is provided at the bottom end of the tube portion 101. The growth vessel 100 has a structure in which other components for growing the epitaxial layer 11 are arranged in the hollow portion 101a, and the pressure in the hollow portion 101a can be maintained at a predetermined pressure by evacuating it.

The raw material supply chamber 110 is configured by providing a base material made of graphite, silicon carbide (SiC), boron nitride (BN), etc. with a coating film made of a material that is difficult to thermally etch, a high-melting point metal material, and a material to which a GaN layer that becomes the epitaxial layer 11 is difficult to adhere, or a coating film made of boron nitride. The raw material supply chamber 110 has one end attached to the first lid 102 so that the other end faces the second lid 103. Examples of materials that are difficult to thermally etch, a high-melting point metal material, and a material to which a GaN layer is difficult to adhere include tantalum carbide (TaC), tungsten (W), tungsten carbide (WC), niobium carbide, etc. The coating film is configured with at least one of these materials as the main component.

The first to fifth supply pipes 210 to 250 are provided on the first lid 102. Specifically, the first supply pipe 210 is a pipe that supplies gallium trichloride gas into the growth vessel 100 as a gallium-based gas for growing the epitaxial layer 11 made of GaN. The second supply pipe 220 is a pipe that supplies ammonia gas into the growth vessel 100 as an ammonia-based gas for growing the epitaxial layer 11 together with the gallium-based gas. The third supply pipe 230 is a pipe that supplies hydrogen gas for reacting with the gallium trichloride gas to generate gallium monochloride gas. The first to third supply pipes 210 to 230 are provided on the first lid 102 so that one end side is located in the raw material supply chamber 110.

In this embodiment, the first to third supply pipes 210 to 230 are supplied with nitrogen gas as a carrier gas together with the above gases. In this embodiment, in order to prevent clogging of the first supply pipe 210, chlorine gas is periodically supplied to the first supply pipe 210 as an etching gas. In this embodiment, a gas containing gallium trichloride gas and ammonia gas corresponds to the reactive gas. In addition, the manufacturing apparatus 1 of this embodiment is provided with the first to third supply pipes 210 to 230 on the first lid portion 102, and as described later, the wafer heating susceptor 130 on which the seed substrate 10 is placed is disposed below the first to third supply pipes 210 to 230. Therefore, the reactive gas supplied from the first to third supply pipes 210 to 230 is supplied along the normal direction to one surface 130a of the wafer heating susceptor 130 described later. Therefore, the manufacturing apparatus 1 of this embodiment can be said to have a downflow type gas supply structure that blows the reactive gas down toward the seed substrate 10.

The fourth supply pipe 240 and the fifth supply pipe 250 are pipes that supply carrier gas into the growth vessel 100 to prevent the reaction gas from flowing around to the first lid 102 side. For example, nitrogen gas is used as the carrier gas supplied to the fourth and fifth supply pipes 240 and 250. The fourth supply pipe 240 and the fifth supply pipe 250 are provided on the first lid 102 so that one end side is located outside the raw material supply chamber 110. In this embodiment, an example in which the fourth supply pipe 240 and the fifth supply pipe 250 are each provided will be described, but only one of the pipes may be provided, or the fourth supply pipe 240 and the fifth supply pipe 250 may be integrated. In addition, the fourth supply pipe 240 and the fifth supply pipe 250 may be provided in a plurality on the circumference.

The rotating device 120 is disposed below the raw material supply chamber 110 (i.e., on the second lid portion 103 side). In this embodiment, the rotating device 120 has a wafer heating susceptor 130 on which a seed substrate 10 made of GaN for growing an epitaxial layer 11 is disposed, and a shaft 140 (i.e., a rotating shaft) connected to the wafer heating susceptor 130.

The wafer heating susceptor 130, like the raw material supply chamber 110, is configured by providing a base material made of graphite or the like with a coating film made of a material that is difficult to thermally etch, a high melting point metal material, and a material to which a GaN layer is difficult to adhere, or a coating film made of boron nitride. The seed substrate 10 is attached to one surface 130a of the wafer heating susceptor 130 located on the first to third supply pipes 210 to 230 side. In this embodiment, the wafer heating susceptor 130 has a recess 131 formed on one surface 130a in which the seed substrate 10 is placed. The seed substrate 10 is placed in the recess 131.

The shaft 140 is connected to the surface of the wafer heating susceptor 130 opposite to the surface 130a on which the seed substrate 10 is placed. The wafer heating susceptor 130 is rotated with the rotation of the shaft 140, and is displaced together with the wafer heating susceptor 130 as the shaft 140 displaces along the axial direction of the growth vessel 100 (i.e., the vertical direction of the paper in FIG. 1). The shaft 140, like the raw material supply chamber 110, is configured to be provided with a coating film made of a material that is difficult to thermally etch, a high-melting point metal material, and a material to which a GaN layer is difficult to adhere, or a coating film made of boron nitride, on a base material made of graphite or the like.

The rotating device 120 of this embodiment is formed with a dilution gas passage 150 for supplying dilution gas into the growth vessel 100 from around the recess 131 on one surface 130a of the wafer heating susceptor 130. The dilution gas passage 150 is formed, for example, by arranging piping or the like that constitutes the dilution gas passage 150 inside the rotating device 120. The dilution gas may be, for example, argon gas, helium gas, nitrogen gas, chlorine gas, hydrogen chloride gas, ammonia gas, or the like.

Here, the raw material supply chamber 110 of this embodiment is configured with a tapered portion 111 having a tapered shape at one end located on the second lid portion 103 side. Specifically, the tapered portion 111 passes through one end located on the second lid portion 103 side, and the distance between the opposing side surfaces is adjusted so that a virtual line K along the normal direction (i.e., the axial direction of the growth vessel 100) to the surface direction of the seed substrate 10 intersects with the seed substrate 10. In other words, the raw material supply chamber 110 is configured with a tapered portion 111 on one end side so that the reaction gas is unlikely to directly reach the outer edge of the seed substrate 10. For example, since the GaN wafer 12 to be manufactured usually has multiple chip formation regions in the surface direction of the GaN wafer 12, the tapered portion 111 is configured so that the virtual line K intersects with the part located at the outermost edge of the multiple chip formations.

The rotation displacement mechanism 160 is a member that includes gears, a motor, and the like, and is connected to the shaft 140 to rotate and displace the shaft 140. When displacing the shaft 140, the rotation displacement mechanism 160 displaces the shaft 140 (i.e., the seed substrate 10) so that the temperature of the growth surface of the epitaxial layer 11 becomes a temperature suitable for growth as the epitaxial layer 11 grows. In addition, when growing the epitaxial layer 11, the rotation displacement mechanism 160 of this embodiment rotates the shaft 140 so that the wafer heating susceptor 130 rotates at 200 or more revolutions per minute, although this is not particularly limited.

The heating device 170 heats the raw material supply chamber 110 and the inside of the growth vessel 100, and is composed of a heating coil such as an induction heating coil or a direct heating coil, and is arranged to surround the periphery of the growth vessel 100.

The above is the configuration of the manufacturing apparatus 1 in this embodiment. Next, we will explain the method for manufacturing the epitaxial layer 11 (i.e., the GaN wafer 12) using the manufacturing apparatus 1.

First, the above-mentioned manufacturing apparatus 1 is prepared, and the seed substrate 10 is placed in the recess 131 formed on one surface 130a of the wafer heating susceptor 130. Then, the rotation displacement mechanism 160 rotates the wafer heating susceptor 130 via the shaft 140 and adjusts the position of the wafer heating susceptor 130. When the epitaxial layer 11 is being grown, the height of the wafer heating susceptor 130 is adjusted in accordance with the growth rate of the epitaxial layer 11. This keeps the height of the growth surface of the epitaxial layer 11 almost constant, making it possible to effectively control the temperature distribution of the growth surface temperature.

Next, while supplying nitrogen gas from the first to fifth supply pipes 210 to 250, the pressure inside the growth vessel 100 is maintained at approximately atmospheric pressure by adjusting the opening and closing rate of the exhaust valve. Note that nitrogen gas is supplied from the first to fifth supply pipes 210 to 250 at approximately 5 slm, for example.

Then, the heating device 170 is driven so that the temperature of the seed substrate 10 is first set to about 500°C. Then, ammonia gas is supplied from the second supply pipe 220 into the growth vessel 100. This makes it possible to prevent nitrogen from escaping from the seed substrate 10 when the temperature of the seed substrate 10 is increased.

Then, the heating device 170 is adjusted so that the temperature of the seed substrate 10 becomes about 1050°C, which is the growth temperature of the epitaxial layer 11. Then, gallium trichloride gas is supplied to the growth vessel 100 from the first supply pipe 210, and hydrogen gas is supplied to the growth vessel 100 from the second supply pipe 240.

As a result, gallium monochloride is produced in the growth vessel 100 by the reaction of the following chemical formula 1.

(Chemical formula 1) _GaCl3 + _H2- >GaCl+2HCl
Then, the ammonia gas and the gallium monochloride gas react on the seed substrate 10, and an epitaxial layer 11 made of GaN grows as shown in Chemical Formula 2 below.

(Chemical formula 2) GaCl + _NH3 → GaN + HCl + _H2
In order to grow the epitaxial layer 11 of the GaN layer on the seed substrate 10, gallium monochloride gas may be introduced directly into the growth vessel 100 from the first supply pipe 210. However, gallium monochloride gas is a gas that is difficult to flow because of its lower vapor pressure at low temperatures such as in the pipe than gallium trichloride gas. For this reason, in this embodiment, since it is difficult to supply gallium monochloride gas to the first supply pipe 210, gallium trichloride gas is supplied to the growth vessel 100 and then changed to gallium monochloride gas to grow the epitaxial layer 11 of the GaN layer.

In addition, immediately before or at the same time that gallium trichloride gas is supplied from the first supply pipe 210 into the growth vessel 100, a dilution gas is supplied from the dilution gas passage 150. As a result, as shown in FIG. 2, the reaction gas supplied onto the outer edge side of the seed substrate 10 is diluted, and excessive growth of the epitaxial layer 11 on the outer edge of the seed substrate 10 can be suppressed. The flow rate of the dilution gas is, for example, about several tens to several hundreds of sccm.

When a gas containing at least one of argon gas, helium gas, and nitrogen gas is supplied as the dilution gas, these gases are gases that do not easily react with the seed substrate 10 or the reaction gas. Therefore, the reaction gas supplied to the outer edge side of the seed substrate 10 can be diluted without affecting the quality of the epitaxial layer 11, and the occurrence of an epicrown can be suppressed.

When a gas containing at least one of chlorine gas and hydrogen chloride gas is supplied as a dilution gas, these gases are etching gases. Therefore, the reaction gas supplied onto the outer edge side of the seed substrate 10 can be diluted while suppressing the precipitation of gallium in the seed substrate 10 and the grown epitaxial layer 11. Therefore, it is possible to grow a higher quality epitaxial layer 11 while suppressing the occurrence of an epicrown.

When ammonia gas is supplied as the dilution gas, the ammonia gas reacts with gallium monochloride gas to form GaN. Here, according to the study by the inventors, it has been confirmed that the crystallinity of the outer edge of the epitaxial layer 11 grown on the seed substrate 10 may be lower than that of the inner edge. Although the exact reason for this phenomenon is not clear, the inventors presume that the crystallinity is lowered because the supply of ammonia gas is reduced, although the epicrown is more likely to occur toward the outer edge of the seed substrate 10. And, according to the study by the inventors, it has been confirmed that the crystallinity of the outer edge of the epitaxial layer 11 can be improved by supplying ammonia gas as the dilution gas. Therefore, by supplying ammonia gas as the dilution gas, it is possible to improve the crystallinity of the epitaxial layer 11 grown on the outer edge of the seed substrate 10 while suppressing the occurrence of the epicrown.

After the epitaxial layer 11 is grown on the seed substrate 10 to produce the GaN wafer 12, the supply of gallium trichloride gas, hydrogen gas, and ammonia gas is stopped. Then, the operation of the heating device 170 is stopped, the growth vessel 100 is filled with nitrogen gas, and the GaN wafer 12 is removed.

According to the embodiment described above, when the epitaxial layer 11 is grown on the seed substrate 10, the reaction gas supplied to the outer edge of the seed substrate 10 is diluted with a dilution gas. This makes it possible to prevent the epitaxial layer 11 from growing too fast at the outer edge of the seed substrate 10. This makes it possible to prevent the epicrown from occurring, and improves the in-plane uniformity of the epitaxial layer 11.

(1) In this embodiment, by using a gas containing at least one of argon gas, helium gas, and nitrogen gas as the dilution gas, it is possible to suppress the occurrence of epicrown without affecting the quality of the epitaxial layer 11.

(2) In this embodiment, by using a gas containing at least one of chlorine gas and hydrogen chloride gas as the dilution gas, it is possible to grow a high-quality epitaxial layer 11 while suppressing the occurrence of epicrowns.

(3) In this embodiment, by using a gas containing ammonia gas as the dilution gas, it is possible to improve the crystallinity of the epitaxial layer 11 growing on the outer edge of the seed substrate 10 while suppressing the generation of an epicrown.

(4) In this embodiment, one end of the raw material supply chamber 110 is formed so that the imaginary line K intersects with the seed substrate 10. This makes it difficult for the reaction gas supplied into the raw material supply chamber 110 to directly reach the outer edge of the seed substrate 10, further suppressing the occurrence of an epicrown.

Second Embodiment
A second embodiment will be described. This embodiment is different from the first embodiment in that the configuration of the raw material supply chamber 110 is changed. As the rest is similar to the first embodiment, the description will be omitted here.

In the manufacturing apparatus 1 of this embodiment, the raw material supply chamber 110 is provided with a gas convection suppression plate 181, a shower head 182, and a gas partition plate 183. Specifically, the gas convection suppression plate 181 is provided between one end and the other end of the raw material supply chamber 110, and is provided to separate a lower space S1 on the one end side from an upper space S2 on the other end side.

The shower head 182 is configured by forming multiple through holes 182a in a plate member, and is provided at the opening on one end side of the raw material supply chamber 110 (i.e., the tapered portion 111).

The gas partition plate 183 is arranged to divide the lower space S1 into a first space S1a and a second space S1b. One ends of the first and third supply pipes 210, 230 are arranged to be located in the first space S1a. One end of the second supply pipe 220 is arranged to be located in the second space S1b.

In the present embodiment described above, the reactive gas supplied to the outer edge of the seed substrate 10 is diluted with a dilution gas, so that the same effect as in the first embodiment can be obtained.

(1) In this embodiment, the lower space S1 is divided into a first space S1a and a second space S1b, one end of the first and third supply pipes 210 and 230 is provided in the first space S1a, and one end of the second supply pipe 220 is provided in the second space S1b. Therefore, first, it is possible to suppress the reaction between gallium trichloride gas and ammonia gas in the raw material supply chamber 110. In addition, since one end of the first and third supply pipes 210 and 230 is provided in the first space S1a, it is possible to change the gallium trichloride gas into gallium monochloride gas in the first space S1a. Therefore, it is possible to suppress the retention of unreacted gallium trichloride gas on the seed substrate 10, and it is possible to facilitate the growth of the epitaxial layer 11.

Other Embodiments
Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also encompasses various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure.

For example, in each of the above embodiments, an example is described in which a rotation displacement mechanism 160 is provided to rotate and displace the wafer heating susceptor 130, but the wafer heating susceptor 130 may be rotated without being displaced. Also, the exhaust port 104 may be disposed on the first lid 102 side of the growth vessel 100.

In addition, in each of the above embodiments, a manufacturing apparatus 1 that grows an epitaxial layer 11 made of GaN has been described. However, in each of the above embodiments, for example, the manufacturing apparatus 1 may grow an epitaxial layer 11 made of silicon carbide on a seed substrate 10 made of silicon carbide. In this case, the reaction gas may be appropriately changed to a gas required for epitaxial growth of silicon carbide.

10 seed substrate 11 epitaxial layer 100 growth vessel 101a hollow portion 130 wafer heating susceptor 130a one surface 210 to 230 supply pipes

Claims (8)

A semiconductor wafer manufacturing apparatus comprising:
a cylindrical growth vessel (100) into which a reaction gas is introduced and into which an epitaxial layer (11) is grown in a hollow portion (101a) constituting a reaction chamber;
a wafer heating susceptor (130) disposed within the hollow portion of the growth chamber and having a surface (130a) on which a seed substrate (10) on which the epitaxial layer is to be grown is disposed;
a supply pipe (210-230) provided in the growth vessel and supplying a reaction gas for growing the epitaxial layer to the growth vessel along a normal direction to the one surface;
The wafer heating susceptor is a semiconductor wafer manufacturing apparatus configured such that a dilution gas for diluting the reaction gas is supplied to the growth chamber from around the portion of the one surface (130a) on which the seed substrate is placed. The semiconductor wafer manufacturing apparatus according to claim 1, wherein the dilution gas is a gas containing at least one of argon gas, helium gas, and nitrogen gas. The semiconductor wafer manufacturing apparatus according to claim 1, wherein the dilution gas is a gas containing at least one of chlorine gas and hydrogen chloride gas. the reactive gas includes a gallium-based gas and an ammonia-based gas;
2. The semiconductor wafer manufacturing apparatus according to claim 1, wherein the dilution gas is a gas containing an ammonia-based gas. a cylindrical source supply chamber (110) provided in a portion of the growth vessel located above the seed substrate, the source supply chamber having an opening at one end on the seed substrate side;
a supply pipe through which the reaction gas is supplied, one end of which is disposed within the raw material supply chamber;
2. The semiconductor wafer manufacturing apparatus according to claim 1, wherein the raw material supply chamber is shaped so that a virtual line (K) passing through the opening and aligned along a normal direction to one surface of the wafer heating susceptor intersects with the seed substrate. a cylindrical source supply chamber (110) provided in a portion of the growth vessel located above the seed substrate, the source supply chamber having an opening at one end on the seed substrate side;
The raw material supply chamber is provided at one end with a shower head (182) having a through hole (182a) formed in a plate member, and is provided with a gas convection suppression plate (181) between the one end and the other end opposite thereto, which separates a lower space (S1) on the one end side from an upper space (S2) on the other end side, and further includes a gas partition plate (183) between the shower head and the gas convection suppression plate, which separates the lower space into a first space (S1a) and a second space (S1b);
The supply pipe includes a first supply pipe (210) for supplying a gallium-based gas and a second supply pipe (220) for supplying an ammonia-based gas;
the first supply pipe is disposed to supply the gallium-based gas to the first space;
2 . The semiconductor wafer manufacturing apparatus according to claim 1 , wherein the second supply pipe is disposed so as to supply the ammonia-based gas to the second space. The semiconductor wafer manufacturing apparatus according to claim 5 or 6, wherein the raw material supply chamber is configured by coating a base material with a coating film mainly composed of at least one of tantalum carbide, tungsten, tungsten carbide, and niobium carbide, or a coating film composed of boron nitride. The semiconductor wafer manufacturing apparatus according to claim 1, wherein the wafer heating susceptor is configured such that the base material is coated with a coating film mainly composed of at least one of tantalum carbide, tungsten, tungsten carbide, and niobium carbide, or a coating film composed of boron nitride.

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