JPH09298232A5 - Method for manufacturing a substrate holder - Google Patents

Description

[Claims]
1. A method for manufacturing a substrate holder for holding a semiconductor crystal growth substrate, comprising:
the substrate holder has a substrate holding portion which is an area for holding a substrate and a substrate non-holding portion which is an area for not holding a substrate,
A method for manufacturing a substrate holder, characterized in that recesses or protrusions having a diameter of 50 microns or more are formed on the upper surface of the non-substrate-holding portion by shot peening .

The present invention relates to a method for manufacturing a substrate holder .

[0012]
[Means for solving the problem]
To achieve the above-mentioned object , the present invention is a method for manufacturing a substrate holder for holding a substrate for semiconductor crystal growth, the substrate holder having a substrate holding portion which is an area for holding a substrate, and a non-substrate holding portion which is an area for not holding a substrate, and the method is characterized in that a recess or protrusion having a diameter of 50 microns or more is formed on the upper surface of the non-substrate holding portion by shot peening .

Since the upper surface of the non- substrate -holding portion has a recess or protrusion with a diameter of 50 microns or more, the surface area of the upper surface of the non-substrate-holding portion is large from the first crystal growth process during manufacturing, and therefore the surface area does not increase even if the semiconductor crystals deposited on the upper surface of the non-substrate-holding portion grow dendrites.

[0051]
[Embodiments of the Invention]
( First Reference Form )
A first embodiment of the present invention will be described with reference to the drawings.

1(a) and 1(b) are views showing a substrate holder according to a first embodiment of the present invention, where 1(a) is a plan view and 1(b) is a cross-sectional view taken along line I-I in 1(a). 1(c) is a cross-sectional view of a substrate holder according to a first modification of the first embodiment . The substrate holder 10A shown in 1(a) is made of a high-melting-point metal such as molybdenum and includes a substrate-holding portion 11 for holding a substrate for crystal growth of a semiconductor crystal, and a non-substrate-holding portion 12, the upper surface of which, excluding the substrate-holding portion 11, is covered with a polycrystalline substrate having a lattice mismatch rate of 10% or less with the crystal lattice of the substrate for crystal growth. The substrate holder 10A is intended to be used in place of the substrate holder 106 on the turntable 105 in the conventional semiconductor manufacturing apparatus shown in 10 or 12.

As described above, according to this embodiment , the upper surface of the non-substrate-holding portion 12 of the substrate holder 10A is covered with a polycrystalline substrate having a lattice mismatch rate of 10% or less with the crystal lattice of the crystal growth substrate. Therefore, the semiconductor crystal deposited on the upper surface of the non-substrate-holding portion 12 grows epitaxially, allowing nucleation to proceed smoothly and resulting in a flat surface without dendritic growth. As a result, the surface area of the non-substrate-holding portion 12 does not increase, and therefore, even if the crystal growth process is repeated multiple times during manufacturing, the amount of radiation from the non-substrate-holding portion 12 does not increase. This keeps the crystal growth temperature constant, ensuring consistently high-quality semiconductor crystals. The fact that lattice mismatch does not occur with a polycrystalline substrate having a lattice mismatch rate of 10% or less was empirically discovered through numerous trials.

( Second Reference Form )
A second embodiment of the present invention will be described below with reference to the drawings.

2(a) and 2(b) show a substrate holder according to a second embodiment of the present invention, with 2(a) being a plan view and 2(b) being a cross-sectional view taken along line II-II in 2(a). The substrate holder 20 shown in 2(a) is a substrate holder made of a high-melting-point metal such as molybdenum. It comprises a substrate-holding portion 21 for holding a substrate for crystal growth of a semiconductor crystal, and a non-substrate-holding portion 22, the upper surface of which, excluding the substrate-holding portion 21, is densely covered with a plurality of single-crystal substrates made of the same material as the crystal growth substrate. The substrate holder 20 is intended to be used in place of the substrate holder 106 on the turntable 105 in the conventional semiconductor manufacturing apparatus shown in 10 or 12.

In the first reference embodiment , the upper surface of the non-substrate holding portion 12 of the substrate holder 10A is covered with a large-diameter polycrystalline substrate, but in this reference embodiment , the upper surface of the non-substrate holding portion 22 of the substrate holder 20 is densely covered with a plurality of single-crystal substrates made of the exact same material as the crystal growth substrate.

Furthermore, since crystals of semiconductors made of Si (silicon) or compound semiconductors made of InP (indium phosphide), GaAs (gallium arsenide), etc. can be lattice-matched to the (1-10) plane of iron or cobalt, the non-substrate-holding portions of the substrate holder described in Figure 1 or Figure 2 may be covered with iron or cobalt having the (1-10) plane.

Furthermore, even if the non-substrate-holding portion is coated with a van der Waals material such as ammonium or sulfur, the van der Waals material does not have bonds on its surface, so the crystals of semiconductors made of Si or compound semiconductors made of InP or GaAs grow according to their own lattice constants, and no lattice mismatch occurs. Therefore, the same effects as those of the first and second embodiments can be obtained.

( First embodiment )
A first embodiment of the present invention will be described below with reference to the drawings.

3(a) and 3(b) are diagrams showing a substrate holder according to a first embodiment of the present invention, where 3(a) is a plan view and 3(b) is a cross-sectional view taken along line III-III in 3(a). The substrate holder 30 shown in 3(a) is a substrate holder made of a high-melting-point metal such as molybdenum, and is composed of a substrate-holding portion 31 for holding a substrate for crystal growth of a semiconductor crystal, and a non-substrate-holding portion 32 having a recess or protrusion with a diameter of 50 μm or more formed on the upper surface of the substrate holder 30 excluding the substrate-holding portion 31. The substrate holder 30 is intended to be used in place of the substrate holder 106 on the turntable 105 in the conventional semiconductor manufacturing apparatus shown in 10 or 12.

A feature of this embodiment is that the non-substrate-holding portion 32, made of a high-melting-point metal such as molybdenum, has recesses or protrusions with a diameter of 50 μm or more formed on its upper surface by shot peening or the like. Therefore, even during the initial crystal growth process during manufacturing, the surface area of the non-substrate-holding portion 32 is sufficiently large, so that the surface area of the non-substrate-holding portion 32 changes very little even after multiple crystal growth processes. As a result, the amount of radiation from the non-substrate-holding portion 32 does not change, so the crystal growth temperature remains constant and high-quality semiconductor crystals can be obtained.

( Third Reference Form )
A third embodiment of the present invention will be described below with reference to the drawings.

4(a) and 4(b) are diagrams showing a substrate holder according to a third embodiment of the present invention, with 4(a) being a plan view and 4(b) being a cross-sectional view taken along line IV-IV in 4(a). The substrate holder 40 shown in 4(a) is a substrate holder made of a high-melting-point metal such as molybdenum. It comprises a substrate-holding portion 41 for holding a substrate for crystal growth of a semiconductor crystal, and a non-substrate-holding portion 42, the upper surface of which, excluding the substrate-holding portion 41, is covered with a heat-equalizing plate made of stainless steel or molybdenum and attached with three screws 42a. The substrate holder 40 is intended to be used in place of the substrate holder 106 on the turntable 105 in the conventional semiconductor manufacturing apparatus shown in 10 or 12.

A feature of this embodiment is that the heat spreader plate covering the upper surface of the non-substrate-holding portion 42 of the substrate holder 40 is attached to the substrate holder 40 with only three screws 42a, and a space is formed between the heat spreader plate and the non-substrate-holding portion 42 of the substrate holder 40, which makes it difficult for heat from the substrate holder 40 to be directly transferred to the heat spreader plate, so the temperature of the heat spreader plate is lower than that of the crystal growth substrate in contact with the substrate-holding portion 41. As a result, the temperature of the heat spreader plate is lower than that of the crystal growth substrate, which makes it difficult for the source gas to thermally decompose, making it difficult for crystals to grow on the upper surface of the heat spreader plate and reducing the amount of radiation from the heat spreader plate. Therefore, even if the crystal growth process is repeated multiple times during manufacturing, the surface area of the non-substrate-holding portion 42 hardly changes, and the amount of radiation from the non-substrate-holding portion 42 does not change, so the crystal growth temperature remains constant and high-quality semiconductor crystals can be obtained.

( Fourth Reference Form )
A fourth embodiment of the present invention will be described below with reference to the drawings.

5(a) and (b) are views showing a substrate holder according to a fourth embodiment of the present invention, where (a) is a plan view and (b) is a cross-sectional view taken along line V-V in (a). The substrate holder 50 shown in (a), which is a substrate holder made of a high-melting-point metal such as molybdenum, comprises a substrate-holding portion 51 for holding a substrate for crystal growth of a semiconductor crystal, and a non-substrate-holding portion 52 formed so that the upper surface of the region of the substrate holder 50 excluding the substrate-holding portion 51 is lower than the upper surface of the substrate-holding portion 51. The substrate holder 50 is intended to be used in place of the substrate holder 106 on the turntable 105 in the conventional semiconductor manufacturing apparatus shown in FIG. 10 or 12.

A feature of this embodiment is that the upper surface of non-substrate-holding portion 52 of substrate holder 50 is formed to be lower than the upper surface of substrate-holding portion 51, and therefore is outside the boundary layer where thermal decomposition of the source gas progresses, which is set based on the upper surface of substrate-holding portion 51, making it difficult for thermal decomposition of the source gas to progress on the upper surface of non-substrate-holding portion 52, and therefore making it difficult for crystals to grow on the upper surface of non-substrate-holding portion 52. Therefore, even if the crystal growth process is repeated many times during manufacturing, the surface area of non-substrate-holding portion 52 hardly changes, and the amount of radiation from non-substrate-holding portion 52 does not change, so the crystal growth temperature remains constant and good quality semiconductor crystals can be obtained.

Furthermore, in each of the reference embodiments , when the non-substrate-holding portions of the substrate holder are made of a material different from that of the semiconductor crystal being grown, if the non-substrate-holding portions are made of a material having an emissivity equivalent to that of the semiconductor crystal, the emissivity of the non-substrate-holding portions during the initial crystal growth process during manufacture will not change from the emissivity of the non-substrate-holding portions after multiple growth processes have been performed. Therefore, when performing temperature correction by measuring the radiant light from the surface of the substrate holder as described with reference to Figure 11(a), the emissivity will not change, and the surface temperature of the substrate holder can be measured accurately.

Furthermore, the substrate holder according to each of the reference embodiments of the present invention can be applied to a substrate holder in a semiconductor manufacturing apparatus that includes a reaction chamber for thermally decomposing a gas that is a raw material for semiconductor crystals, a gas inlet that introduces the raw material gas from outside the reaction chamber into the reaction chamber, a turntable that is arranged directly below the gas inlet so as to block the flow of the raw material gas blown out from the gas inlet and that rotates at high speed by a turntable drive shaft, a substrate holder that is fixed to the turntable and holds a substrate for crystal growth, and a heater as heating means for heating the substrate for crystal growth; however, the overall configuration of the semiconductor device is similar to that of the conventional one described based on Figure 9, so description thereof will be omitted.

( Fifth embodiment )
A crystal growth method according to the fifth embodiment of the present invention will now be described.

In each of the reference embodiments and conventional substrate holders having a substrate-holding portion that holds a substrate for crystal growth and a substrate-non-holding portion excluding the substrate-holding portion, if the lattice mismatch rate between the components of the substrate-non-holding portion and the semiconductor crystal to be grown is not within 10%, dendrite-type crystals will accumulate on the substrate-non-holding portion, although the degree will vary depending on the component and the shape of the component.

( Sixth embodiment )
A method for measuring the substrate temperature in a semiconductor manufacturing method according to a sixth embodiment of the present invention will now be described with reference to the drawings.

In this embodiment , the substrate temperature is measured with the focus on the fact that the dopant incorporation efficiency varies greatly depending on the substrate temperature. For example, when adding Zn (zinc) as a p-type dopant to manufacture a semiconductor crystal made of InP, even if a source gas containing the same amount of Zn element is added, it can be seen that the hole concentration of the semiconductor crystal made of InP varies depending on the substrate temperature, as shown in Figure 6. This is because the concentration of Zn incorporated into the crystal differs depending on the substrate temperature.

As described above, according to this embodiment , in a heat treatment process including not only a semiconductor film formation process but also a diffusion process, a substrate temperature evaluation function that represents the relationship between the substrate temperature of a desired semiconductor and the ratio of the dopant addition amount to the carrier concentration of the semiconductor is calculated in advance as a preparation process, and the temperature of the film formation process or the diffusion process is controlled using the substrate temperature evaluation function, thereby making it possible to obtain high-quality semiconductor crystals.

( Seventh embodiment )
A method for measuring the substrate temperature in a semiconductor manufacturing method according to the seventh embodiment of the present invention will now be described.

As described above, according to the present embodiment , in the heat treatment process including not only the semiconductor film formation process but also the diffusion process, a substrate temperature evaluation function is obtained in advance as a preparation process, which represents the relationship between the desired semiconductor substrate temperature and the supply ratio of at least the first group V gas and the second group V gas, for example, arsine and phosphine, such that the energy band gap and the lattice constant of the semiconductor are both equal. The substrate temperature evaluation function is then used to control the temperature of the film formation process or the diffusion process, so that a high-quality III-V group semiconductor crystal consisting of a quaternary mixed crystal can be obtained.

Hereinafter, a semiconductor manufacturing method according to the sixth or seventh embodiment of the present invention will be specifically described with reference to the drawings.

First, a substrate temperature evaluation function is defined from the relationship between the carrier concentration and the substrate temperature shown in the sixth embodiment , or from the relationship between the supply ratio of at least the first group V gas and the second group V gas and the substrate temperature shown in the seventh embodiment .

( Eighth embodiment )
An eighth embodiment of the present invention will be described below with reference to the drawings.

9 is a front view of a semiconductor manufacturing apparatus according to an eighth embodiment of the present invention. As shown in Fig. 9, this semiconductor manufacturing apparatus comprises a reaction chamber 61 for thermally decomposing a source gas for semiconductor crystals, a gas inlet 62 for introducing the source gas from outside the reaction chamber 61 into the reaction chamber 61, a turntable 65 rotates at 500 rpm or more by a turntable drive shaft 64, and a substrate holder 66 made of a metal such as stainless steel or molybdenum. The turntable 65 is located directly below the turntable 65 so as to interrupt a flow 63 of source gas emitted from the gas inlet 62. The turntable 65 has a substrate holding portion for holding a substrate for crystal growth and a non-substrate holding portion other than the substrate holding portion. A monitor thermocouple 67 serves as a first temperature detector for detecting the temperature of the turntable 65, a heater 68 serves as a heating means for heating the substrate for crystal growth, and a control thermocouple 69 serves as a second temperature detector for detecting the temperature of the heater 68.

As described above, according to this embodiment , the temperature of the substrate holder 66 is measured by the monitor thermocouple 67 installed near the turntable, without measuring the radiant light on the surface of the substrate holder as shown in FIG. 12. Therefore, the measurement error of the substrate temperature does not increase with each crystal growth process, and the temperature of the substrate holder can be accurately controlled, thereby enabling the production of high-quality semiconductor crystals.

A manufacturing method using a manufacturing apparatus according to the eighth embodiment of the present invention will be described below.

[0104]
[Effects of the Invention]
With the substrate holder obtained by the present invention , the surface area of the non-substrate-holding portions of the substrate holder is large from the first crystal growth process during manufacturing, so even if the semiconductor crystals deposited on the non-substrate-holding portions of the substrate holder undergo dendritic growth, the surface area does not increase, and the amount of radiation from the substrate holder does not change regardless of the number of times the crystal growth process is performed.As a result, the temperature of the substrate holder does not change, and the crystal growth temperature of the crystal growth substrate held by the substrate holder can be maintained constant.

[Brief explanation of the drawings]
Figure 1
FIG. 1 is a diagram showing a substrate holder according to a first embodiment of the present invention;
(a) is a plan view;
(b) is a cross-sectional view taken along line I-I in (a);
1C is a cross-sectional view of a substrate holder according to a first modified example of the first embodiment .
Figure 2
FIG. 10 is a diagram showing a substrate holder according to a second embodiment of the present invention;
(a) is a plan view;
1B is a cross-sectional view taken along line II-II in FIG.
Figure 3
FIG. 1 is a diagram showing a substrate holder according to a first embodiment of the present invention;
(a) is a plan view;
1B is a cross-sectional view taken along line III-III in FIG.
Figure 4
FIG. 10 is a diagram showing a substrate holder according to a third embodiment of the present invention;
(a) is a plan view;
4B is a cross-sectional view taken along line IV-IV in FIG.
Figure 5
FIG. 10 is a diagram showing a substrate holder according to a fourth embodiment of the present invention;
(a) is a plan view;
1B is a cross-sectional view taken along line V-V in FIG.
Figure 6
FIG. 13 is a graph showing the correlation between the substrate temperature and the hole concentration of a semiconductor crystal in a semiconductor manufacturing method according to a sixth embodiment of the present invention.
Figure 7
FIG. 10 is a graph of an evaluation function showing the relationship between the grown film thickness of a crystal deposited on a substrate holder and the substrate temperature in the semiconductor manufacturing method according to the sixth or seventh embodiment of the present invention.
Figure 8
FIG. 10 is a graph showing the correlation between the set temperature and the grown film thickness of the crystal deposited on the substrate holder in the semiconductor manufacturing method according to the sixth or seventh embodiment of the present invention.
Figure 9
FIG. 13 is a front view of a semiconductor manufacturing apparatus according to an eighth embodiment of the present invention.
Figure 10
(a) is a front view of a conventional semiconductor manufacturing apparatus;
10(b) to 10(d) are cross-sectional views of a substrate holder at each conventional crystal growth step.
Figure 11
FIG. 1 is a graph showing the correlation between the grown film thickness of a crystal deposited on a conventional substrate holder and the substrate temperature.
Figure 12
1A is a front view of a semiconductor manufacturing apparatus having a conventional temperature compensation device;
FIG. 1B is a plan view of a conventional substrate holder.
[Explanation of symbols]
10A Substrate holder 10B Substrate holder 11 Substrate holding portion 12 Non-substrate holding portion 20 Substrate holder 21 Substrate holding portion 22 Non-substrate holding portion 30 Substrate holder 31 Substrate holding portion 32 Non-substrate holding portion 40 Substrate holder 41 Substrate holding portion 42 Non-substrate holding portion 42a Screw 50 Substrate holder 51 Substrate holding portion 52 Non-substrate holding portion 61 Reaction chamber 62 Gas inlet portion 63 Gas flow 64 Turntable drive shaft 65 Turntable 66 Substrate holder 67 Monitor thermocouple 68 Heater 69 Control thermocouple