JP3758528B2 - Group III nitride compound semiconductor manufacturing apparatus and group III nitride compound semiconductor manufacturing method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for manufacturing a group III nitride compound semiconductor. The present invention is particularly effective as a method or apparatus for producing a thick group III nitride compound semiconductor or a group III nitride compound semiconductor having a thickness that can be handled as an epitaxial growth substrate. The group III nitride compound semiconductor is, for example, a binary system such as AlN, GaN, InN, Al _x Ga _1-x N, Al _x In _1-x N, Ga _x In _1-x N (whichever Also includes ternary systems such as 0 <x <1) and quaternary systems of Al _x Ga _y In _1-xy N (0 <x <1, 0 <y <1, 0 <x + y <1) general formula is _{Al x Ga y in 1-xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) with those represented. In this specification, unless otherwise specified, the group III nitride compound semiconductor is simply referred to as a group III nitride compound semiconductor doped with an impurity for making the conductivity type p-type or n-type. An expression that also includes
[0002]
[Prior art]
For example the general formula _{Al x Ga y In 1-xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) III nitride compound semiconductors in order to obtain the epitaxial growth is the substrate Although necessary, a handleable group III-nitride compound semiconductor substrate is not commercially available. For this reason, inexpensive sapphire substrates, silicon carbide (SiC) substrates, silicon (Si) substrates and other dissimilar substrates are used.
[0003]
[Problems to be solved by the invention]
However, an inexpensive heterogeneous substrate has a lattice constant greatly different from that of a group III nitride compound semiconductor. Therefore, it is common to epitaxially grow a group III nitride compound semiconductor after forming a so-called buffer layer on these different substrates. However, even in such a case, when epitaxial growth is performed at an extremely high temperature of 1000 ° C. or higher and then the temperature is returned to room temperature, a great thermal stress is generated due to a difference in thermal expansion coefficient between the heterogeneous substrate and the group III nitride compound semiconductor. . In other words, even if good epitaxial growth is performed at a high temperature stage, the thermal expansion coefficient of the heterogeneous substrate differs from that of the group III nitride compound semiconductor when cooling to room temperature. Many crystal defects or cracks (cracks) are generated inside the physical compound semiconductor layer.
[0004]
In fact, the linear expansion coefficient is about 5.6 × 10 ^-6 / K for gallium nitride (GaN), about 4.2 × 10 ^-6 / K for aluminum nitride (AlN), and sapphire (α -SiO ₂ ) is about 7.5 × 10 ⁻⁶ / K, and silicon (Si) is about 3.6 × 10 ⁻⁶ / K. Then, if a thick GaN film is formed on a sapphire (α-SiO ₂ ) substrate or a silicon (Si) substrate and then cooled by 1000 K (or ° C.), a shrinkage difference of 0.2% occurs in the a-axis direction. This is to form a GaN having a thickness of several mm on a sapphire (α-SiO ₂₎ substrate or a silicon (Si) substrate, GaN in thermal stress caused by cooling and sapphire (α-SiO ₂₎ substrate or a silicon (Si) It is inevitable that a crack is generated in the substrate.
[0005]
On the other hand, in order to obtain an excellent single crystal group III nitride compound semiconductor, particularly gallium nitride (GaN), by epitaxial growth, it is considered to be almost essential to perform at a high temperature of 1000 ° C. or higher. Accordingly, an object of the present invention is to provide a group III nitride compound that does not cause cracks in the group III nitride compound semiconductor layer even after cooling at a temperature difference of about 1000 ° C. or higher after epitaxial growth. it is to provide a semiconductor manufacturing apparatus.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, according to the means of claim 1, in the group III nitride compound semiconductor manufacturing apparatus, dissimilar substrates for epitaxial growth of the group III nitride compound semiconductor are arranged. , a raw material supply system for epitaxial growth of group III nitride-based compound semiconductor has a structure in which a etchant supply system for separating, one or more group III nitride compound semiconductor on a surface of the heterogeneous substrate The other surface of the heterogeneous substrate can be etched during or after the epitaxial growth. According to a second aspect of the present invention, the heterogeneous substrate is mounted horizontally, and the raw material supply system is at the lower part and the etchant supply system is at the upper part.
[0007]
Further, according to the means of claim 3 , in the method for producing a group III nitride compound semiconductor, the group III nitride compound semiconductor which can be etched using the production apparatus according to claim 1 or claim 2. different substrates (heterogeneous substrate), so that the one surface is in contact with the III group nitride-based compound semiconductor epitaxial growth system, and to the manufacturing apparatus as the other surface is in contact with the etching system, which is separated from the epitaxial growth system and Place one or more Group III nitride compound semiconductors on one side of a heterogeneous substrate in the epitaxial growth system of Group III nitride compound semiconductors, or after etching, dissimilar in etching system The other surface of the substrate is etched to reduce the thickness of most of the different types of substrates . During this, it is also encompassed by the present invention by repeating the one or more Group III nitride compound semiconductor etching the other surface of it and the substrate different to be laminated on one surface of different substrates.
[0008]
According to a fourth aspect of the present invention, the heterogeneous substrate is a silicon (Si) substrate. According to the means described in claim 5 , a gas or a gaseous etchant is used in the etching system. Here, the gaseous state includes a sprayed state (sprayed state). According to a sixth aspect of the present invention, gaseous hydrogen halide is mainly used in the etching system. Here, mainly means that it may be diluted with a carrier gas or the like inert to the reaction system.
[0009]
Further, according to the means described in claim 7 , the epitaxial growth system includes at least one step of a chloride method for transporting gallium (Ga) or indium (In) to a different substrate surface by hydrogen chloride (HCl) gas. And In this method, for example, single gallium (Ga) or indium (In) is held at a high temperature, and hydrogen chloride (HCl) is blown to sublimate the chloride and lead to the epitaxial substrate.
[0010]
[0011]
[0012]
[Operation and effect of the invention]
When epitaxially growing a group III nitride compound semiconductor using a heterogeneous substrate, or after growth, etching from the back surface of the heterogeneous substrate makes it possible to reduce the thickness of most of the heterogeneous substrate. . Of these, when epitaxial growth and etching are performed at the same time, the epitaxial growth is performed in a state where a thin heterogeneous substrate is used after the epitaxial growth is sufficiently performed while using a thick heterogeneous substrate for the initial growth. Means you can exit. That is, even if epitaxial growth of a III-nitride compound semiconductor is started at a high temperature using a thick heterogeneous substrate that is easy to handle, the thin dissimilar substrate will be group III nitride when the epitaxial growth is terminated and the temperature is lowered to room temperature. It is bonded to a physical compound semiconductor. In the case where etching is simultaneously performed after epitaxial growth, the same effect can be obtained by starting etching at a high temperature after epitaxial growth. By using such a manufacturing method, it is possible to remove or completely remove most of the different substrates by etching. In the state where most of the different types of substrates are thinned by etching, it is possible to avoid the occurrence of cracks in the group III nitride compound semiconductor due to thermal stress. In addition, when the heterogeneous substrate is almost removed, the group III nitride compound semiconductor originally grown epitaxially on the heterogeneous substrate becomes a substrate for epitaxial growth, as if the group III nitride compound semiconductor was grown. No thermal stress is generated, and no crack is generated in the group III nitride compound semiconductor .
[0013]
Inexpensive yet was desirable to use easily obtained silicon (Si) substrate that constant quality as etchable foreign substrates. If the etchant with a gas or gaseous Ru readily der be introduced into the etching system. Especially, a hydrogen halide Ru easy der handle.
[0014]
As an epitaxial growth system, the chloride method for transporting gallium (Ga) or indium (In) to a heterogeneous substrate surface by hydrogen chloride (HCl) gas has a high growth rate, so that a thick film Ga _x In _1-x N (0 ≦ It was desired as a method for forming the x ≦ 1).
[0015]
A semiconductor manufacturing apparatus using vapor phase growth having a structure in which a material supply system and an etchant supply system are substantially separated by disposing different types of substrates is a manufacturing apparatus that can realize the above manufacturing method. ( Claim 1 ).
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to a following example.
[0017]
FIG. 1 is a cross-sectional view showing the structure of a semiconductor manufacturing apparatus 100 according to a specific embodiment of the present invention. In FIG. 1, the presence or absence of the connection portion and the details thereof are not shown, but only an outline is shown, and the details of the dissimilar substrate installation portion for epitaxial growth are given in FIG.
[0018]
The semiconductor manufacturing apparatus 100 of FIG. 1 is configured such that the epitaxial growth system 101 and the etching system 102 communicate with each other before the dissimilar substrate 10 is installed, and are isolated by the dissimilar substrate 10 being installed. Note that complete airtightness is not required between the two systems. The semiconductor manufacturing apparatus 100 includes a quartz reaction tube 110 having a structure of two upper and lower tanks, a heterogeneous substrate holder 120, an etching gas introduction tube 130, a group V element introduction tube 140, and a group III element chloride introduction unit 150. . The group III element chloride introduction part 150 includes a hydrogen chloride introduction pipe part 151, a group III element boat 152, and a group III chloride introduction pipe part 153.
[0019]
The lower tank epitaxial growth line 101 has a normal halide VPE configuration. That is, metal gallium or indium is put into the group III element boat 152, hydrogen chloride (HCl) is introduced from the hydrogen chloride introduction pipe part 151, and GaCl is supplied from the group III chloride introduction pipe part 153 toward the heterogeneous substrate 10. On the other hand, ammonia is supplied from the group V element introduction pipe 140. Note that both the group V element introduction pipe 140 and the group III element chloride introduction section 150 may be supplied in a state diluted with a carrier gas.
[0020]
In the etching system 102 of the upper tank, an etching gas introduction pipe 130 is connected to the hole 21 at the center of the soaking plate 20. The details are as shown in the sectional view of FIG. An annular heterogeneous substrate holder 120 having a step is disposed in a quartz reaction tube 110 having a circular heterogeneous substrate installation hole. The heterogeneous substrate 10 is installed on the annular heterogeneous substrate holder 120 from above. The quartz reaction tube 110 is separated into an epitaxial growth system 101 and an etching system 102 by the heterogeneous substrate 10 and the annular heterogeneous substrate holder 120. The annular dissimilar substrate holder 120 has a Z-shaped or S-shaped cross section in the diameter direction. The lower part with the narrower opening supports the heterogeneous substrate 10. At this time, the peripheral edge portion of the lower surface 10 a of the different substrate 10 contacts the annular different substrate holder 120. The upper part of the annular dissimilar substrate holder 120 is the portion with the largest radius, and is configured to hang over the circular dissimilar substrate mounting hole of the quartz reaction tube 110. Thus, one surface (lower surface) 10a of the heterogeneous substrate 10 faces the epitaxial growth system 101, and the other surface (upper surface) 10b of the heterogeneous substrate 10 faces the etching system 102. A pedestal-shaped heat equalizing plate 20 having a hole 21 at the center and four legs 22 at the bottom is installed on the upper surface 10 b of the different substrate 10. The heat equalizing plate 20 prevents the different substrate 10 and the different substrate holder 120 from deviating from the different substrate mounting hole of the quartz reaction tube 110 due to its weight, and stores heat from a heat source outside the quartz reaction tube 110 to store different types of heat. It has a function of keeping the substrate 10 at a desired reaction temperature.
[0021]
The soaking plate 20 is made of carbon and has resistance to an etching gas. In addition, the etching gas introduced from the hole 21 is released to the upper surface 10b of the foreign substrate 10, and the upper surface 10b of the foreign substrate 10 is etched. At this time, the gas generated by the etching reaction passes between the four legs 22 of the soaking plate 20 and is released into the etching system 102 of the quartz reaction tube 110, and then is discharged to the processing system as exhaust.
[0022]
The outline of epitaxial growth using the semiconductor manufacturing apparatus 100 while etching the back surface of a different substrate is as follows. Hereinafter, a state in which a silicon (Si) substrate is used as the heterogeneous substrate 10 and gallium nitride (GaN) is epitaxially grown while etching the back surface with hydrogen chloride will be described with reference to FIG.
[0023]
The silicon (Si) substrate 10 and the soaking plate 20 are held at 1000 ° C. by an external heat source ((a) of FIG. 3). Next, when ammonia (NH ₃ ) and gallium chloride (GaCl) are supplied to the epitaxial system 101, gallium nitride (GaN) 30 starts epitaxial growth on the surface 10a of the silicon (Si) substrate 10 (FIG. 3B). ). Next, hydrogen chloride (HCl) is supplied to the surface 10 b of the silicon (Si) substrate 10 through the hole 21 of the soaking plate 20. Then, the supplied hydrogen chloride (HCl) is reacted in the plane 10b of silicon (Si) substrate 10, chlorosilanes _{(H x SiCl 4-x,} H x Si 2 Cl 6-x, etc.) and hydrogen H ₂ Thus, it is discharged into the etching system 102 from between the four legs 22 of the soaking plate 20, and further discharged to an exhaust gas treatment device (not shown) outside the quartz reaction tube 110. In this way, the side of the silicon (Si) substrate 10 facing the etching system 102 is etched, and the silicon (Si) substrate 10 becomes thinner from the central portion 10c (FIG. 3C). Thus, if the epitaxial growth and etching are continued for a desired time, the silicon (Si) substrate 10 is almost thinned by etching except for the portion in contact with the four leg portions 22 of the soaking plate 20, or is completely removed and nitrided. The back surface of gallium (GaN) 30 is deposited ((d) in FIG. 3).
[0024]
In the above embodiment, the reaction tube is made of quartz, but the present invention can be applied to a manufacturing apparatus made of any material. In the above embodiment, the epitaxial growth by the so-called halide VPE is shown, but the epitaxial growth method is arbitrary. Although silicon (Si) is used as the heterogeneous substrate, the present invention can be applied to any heterogeneous substrate that can be etched. As the etching gas at that time, any gas can be used according to the material of the different substrate and the actual manufacturing apparatus.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the structure of a semiconductor manufacturing apparatus according to a specific embodiment of the present invention.
FIG. 2 is a cross-sectional view showing details of the structure of a dissimilar substrate installation portion of a semiconductor manufacturing apparatus according to a specific embodiment of the present invention.
FIG. 3 is a process chart showing a method for producing a group III nitride compound semiconductor according to a specific example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Semiconductor manufacturing apparatus 101 Epitaxial growth system 102 Etching system 110 Quartz reaction tube 120 Heterogeneous substrate holder 120
130 Etching gas introduction pipe 140 Group V element introduction pipe 150 Group III element chloride introduction section 151 Hydrogen chloride introduction pipe section 152 Group III element boat 153 Group III chloride introduction pipe section 10 Dissimilar substrate 20 Soaking plate 21 Hole 22 Leg Part 30 Gallium Nitride (GaN)

Claims (7)

In the group III nitride compound semiconductor manufacturing equipment,
By disposing a heterogeneous substrate for epitaxially growing a group III nitride compound semiconductor, a material supply system for epitaxially growing a group III nitride compound semiconductor and an etchant supply system are separated,
Group III nitride, wherein the while one or more Group III nitride compound semiconductor on a surface of the heterogeneous substrate is epitaxially grown, or after growing, and the other surface of the substrate different to allow etched ring Physical compound semiconductor manufacturing equipment. 2. The structure according to claim 1, wherein the heterogeneous substrate is placed horizontally, and the raw material supply system is in a lower part and the etchant supply system is in an upper part. III Group nitride compound semiconductor manufacturing equipment. In the method for producing a group III nitride compound semiconductor,
Using the manufacturing apparatus according to claim 1 or claim 2,
Etchable III nitride compound semiconductor different substrate (foreign substrate), one surface is in contact with the III group nitride-based compound semiconductor epitaxial growth system, it is and separated the other surface and the epitaxial growth system Placed on the manufacturing apparatus so as to contact the etching system,
During or after stacking one or a plurality of group III nitride compound semiconductors on one surface of the heterogeneous substrate in an epitaxial growth system of group III nitride compound semiconductor, the heterogeneous substrate is etched by the etching system. A method for producing a group III nitride compound semiconductor, comprising etching the other surface of the substrate to reduce a thickness of a large part of the heterogeneous substrate. 4. The method for producing a group III nitride compound semiconductor according to claim 3 , wherein the heterogeneous substrate is a silicon (Si) substrate. 5. The method for producing a group III nitride compound semiconductor according to claim 3 , wherein a gas or a gaseous etchant is used in the etching system. 5. The method for producing a group III nitride compound semiconductor according to claim 3 , wherein gaseous hydrogen halide is mainly used in the etching system. 7. The method according to claim 3 , wherein the epitaxial growth system includes at least one step of a chloride method for transporting gallium (Ga) or indium (In) to the surface of the heterogeneous substrate with hydrogen chloride (HCl) gas. A method for producing a group III nitride compound semiconductor according to claim 1.

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