Silicon substrate structure

Abstract

To provide a silicon substrate structure capable of stably growing an epitaxial crystal.SOLUTION: A substrate 1 has a first surface and a second surface 12. The first surface is formed on one side of a silicon (111) lattice plane; the second surface 12 is formed on an opposite side of the silicon (111) lattice plane; a first groove 2 is provided in a first direction D1 on the second surface 12 of the substrate 1; a second groove 3 is provided in a second direction D2 on the second surface 12 of the substrate 1; a third groove 4 is provided in a third direction D3 on the second surface 12 of the substrate 1; the first direction D1 is defined as a direction to a silicon (1-1-1) lattice plane from the silicon (111) lattice plane; the second direction D2 is defined as a direction to a silicon (1-11) lattice plane from a silicon (-11-1) lattice plane; and the third direction D3 is defined as a crystal axis direction of a silicon [1-10].SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a silicon substrate structure, and more particularly to a silicon substrate structure having a plurality of grooves formed along a specific lattice direction in order to relieve stress during epitaxial growth. [Background technology]

[0002] Epitaxial technology plays an important role in semiconductor manufacturing and optoelectronics. Two types of materials are mainly used in epitaxial technology: silicon carbide and gallium nitride. The silicon substrate structure formed by the epitaxial growth of the gallium nitride layer is an essential base material for semiconductor devices. From the perspective of manufacturing costs, the current mainstream of gallium nitride substrates is silicon-based gallium nitride technology, which grows gallium nitride epitaxial crystals on silicon substrates. This technology is a heteroepitaxial technology in the semiconductor industry. As the epitaxial crystal grows, the gallium nitride layer becomes thicker and thicker due to high temperature expansion, and the silicon substrate also expands with the increase in temperature. The deformation amount below the silicon substrate also increases with the thickness of the gallium nitride epitaxial layer, and the tensile strain of the substrate gradually increases. When the thickness of the gallium nitride film exceeds a certain threshold, the compressive stress below is transferred to the other direction, and the compression phenomenon becomes more pronounced in the lower lattices. Furthermore, as the temperature increases during epitaxial growth, the thermal expansion of the gallium nitride layer becomes more pronounced, resulting in increased tensile stress and greater bowing in the center of the silicon substrate, adversely affecting epitaxial uniformity.

[0003] By the way, due to the lattice mismatch and the difference in thermal expansion coefficient between two different materials, it is easy for strain to accumulate between different materials. During epitaxial growth, deformation occurs due to the increase in temperature, and when the temperature decreases, the stress is released unevenly, which adversely affects the quality of the epitaxial film or even causes cracks. The methods for improving epitaxial technology using different materials include providing a pattern on the surface of the epitaxial substrate, providing grooves on the surface of the epitaxial substrate and filling them with stress compensation materials, and using a cushion layer structure to absorb stress. All of the above technologies require better epitaxial materials to improve the warping of the substrate at high temperatures, make the heating process uniform, and release the stress uniformly after cooling.

[0004] In view of the above circumstances, the present invention proposes a silicon substrate structure for solving the problems of the prior art, such as poor uniformity of epitaxial growth and susceptibility to cracking. Summary of the Invention

[0005] The object of the present invention is to provide a silicon substrate structure capable of stably growing epitaxial crystals. In the present invention, grooves are formed on the lower surface of the substrate structure based on three specific lattice directions. When the temperature rises, there is room for the lower silicon lattice to be compressed, and the epitaxial layer on the substrate can grow stably. The space of the groove can compensate for the deformation caused by the warping of the substrate and relieve the stress accumulated by the deformation. On the other hand, when the temperature drops, the silicon lattice compressed at a high temperature gradually concentrates, and the cooled gallium nitride layer also brings distortion to the silicon substrate, but the grooves provided in the substrate can reduce the amount of deformation and uniformly release the distortion. Therefore, when the silicon substrate structure according to the present invention is used, the occurrence of cracks can be reduced and uniformity can be improved in the epitaxial process, and the manufacturing yield of the epitaxial film can be improved.

[0006] In order to achieve the above object, the present invention discloses a silicon substrate structure comprising a substrate, a first groove, a second groove, and a third groove. The substrate has a first surface and a second surface. The first surface is formed on one side of a silicon (111) lattice plane. The second surface is formed on the opposite side of the silicon (111) lattice plane. The first groove is provided on the second surface of the substrate along a first direction. The second groove is provided on the second surface of the substrate along a second direction. The third groove is provided on the second surface of the substrate along a third direction. The first direction is defined as a direction from a silicon (111) lattice plane to a silicon (1-1-1) lattice plane. The second direction is defined as a direction from a silicon (-11-1) lattice plane to a silicon (1-11) lattice plane. The third direction is defined as a crystal axis direction of silicon [1-10].

[0007] In an embodiment of the invention, the first direction forms a first angle with a fourth direction of a silicon (111) lattice plane, the second direction forms a second angle with the fourth direction of the silicon (111) lattice plane, the fourth direction is perpendicular to the third direction, and the first angle is substantially equal to the second angle.

[0008] In an embodiment of the present invention, the first angle and the second angle are 35.26±3 degrees.

[0009] In an embodiment of the present invention, the first trench has a plurality of first trenches arranged in parallel to the first direction, the second trench has a plurality of second trenches arranged in parallel to the second direction, and the third trench has a plurality of third trenches arranged in parallel to the third direction.

[0010] In an embodiment of the present invention, any one of the first trench, the second trench, and the third trench is arranged continuously or discontinuously.

[0011] In an embodiment of the invention, the first trench has a first width, the second trench has a second width, and the third trench has a third width, and the first width, the second width, and the third width are equal.

[0012] In an embodiment of the invention, the first width, the second width, and the third width are each between 10 microns and 5 millimeters.

[0013] In an embodiment of the invention, the substrate and the first trench define a first height, the substrate and the second trench define a second height, and the substrate and the third trench define a third height, wherein the first height, the second height, and the third height are equal.

[0014] In an embodiment of the present invention, the first height, the second height, and the third height are each between 500 microns and 2000 microns.

[0015] In an embodiment of the invention, the substrates have a periphery and a secant line that are connected to each other and define the substrate as a non-circular substrate.

[0016] Those skilled in the art can understand other objects of the present invention, as well as the technical means and embodiments of the present invention, by referring to the drawings and the embodiments described below. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing a silicon substrate structure and a gallium nitride layer according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a top view showing a silicon substrate structure according to an embodiment of the present invention; [Diagram 3] Schematic diagram showing a silicon substrate structure according to an embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram showing a silicon substrate structure according to another embodiment of the present invention; [Diagram 5] FIG. 1 is a schematic diagram showing a silicon substrate structure according to another embodiment of the present invention; [Figure 6] FIG. 1 is a schematic diagram showing a silicon substrate structure according to another embodiment of the present invention; [Figure 7] 1 is a side view showing a silicon substrate structure according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The contents of the present invention will be described below through examples. The examples of the present invention are examples of embodiments, and are not intended to limit the present invention to the environments, applications, or specific aspects described in the examples. Therefore, the explanation of the examples is for explaining the present invention, but does not limit the present invention. In the embodiments and drawings, components that are not directly related to the present invention are omitted and not shown. The dimensional relationship between the components in the drawings is for ease of understanding, and does not limit the actual dimensions.

[0019] The following description will be given with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing a silicon substrate structure 1000 and a gallium nitride layer 2000 according to an embodiment of the present invention. Figure 2 is a top view showing the silicon substrate structure 1000 according to an embodiment of the present invention. Gallium nitride 2000 is disposed on the silicon substrate structure 1000. An epitaxial crystal is grown based on the silicon substrate structure 1000 of the present invention. The silicon substrate structure 1000 includes a substrate 1, a first groove 2, a second groove 3, and a third groove 4. The first groove 2, the second groove 3, and the third groove 4 are formed on the same surface of the substrate 1.

[0020] In detail, the substrate 1 is <111> The substrate 1 is a silicon substrate aligned along a crystal orientation. The substrate 1 has a first surface 11, a second surface 12, an outer periphery 13, and a cleavage line 14. The first surface 11 is formed on one side of the silicon (111) lattice plane. In other words, the first surface 11 is the upper surface of the silicon (111) lattice plane of the substrate 1. The second surface 12 is formed on the opposite side of the silicon (111) lattice plane. In other words, the second surface 12 is the lower surface of the silicon (111) lattice plane of the substrate 1. The outer periphery 13 and the cleavage line 14 are both outer edges of the substrate 1. The outer periphery 13 and the cleavage line 14 are connected to each other to define the substrate 1 as a non-circular substrate. In this embodiment, an example is given in which the cleavage line 14 is located at the lower end of the substrate 1, but the position of the cleavage line can be changed according to actual needs and is not limited to this.

[0021] The first groove 2, the second groove 3, and the third groove 4 will be described in detail. The first groove 2 is provided on the second surface 12 of the substrate 1 along a first direction D1. The first groove 2 has a plurality of first trenches 21 arranged parallel to the first direction D1. The second groove 3 is provided on the second surface 12 of the substrate 1 along a second direction D2. The second groove 3 has a plurality of second trenches 31 arranged parallel to the second direction D2. The third groove 4 is provided on the second surface 12 of the substrate 1 along a third direction D3. The third groove 4 has a plurality of third trenches 41 arranged parallel to the third direction D3. The first groove 2, the second groove 3, and the third groove 4 are arranged in the same direction as the crystal lattice. The first direction D1 is defined as the direction from the silicon (111) lattice plane to the silicon (1-1-1) lattice plane. The second direction D2 is defined as the direction from the silicon (-11-1) lattice plane to the silicon (1-11) lattice plane. The third direction D3 is defined as the crystal axis direction of silicon [1-10]. In addition, there is a direction perpendicular to the third direction D3 on the substrate 1, which is defined as the fourth direction D4 on the silicon (111) lattice plane.

[0022] The first direction D1 forms a first angle θ1 with the fourth direction D4. The second direction D2 forms a second angle θ2 with the fourth direction D4. The first angle θ1 is substantially equal to the second angle θ2. In this embodiment, the first angle θ1 and the second angle θ2 are 35.26±3 degrees. In other words, the angle between the first trench 21 and the second trench 31 is the sum of the first angle θ1 and the second angle θ2.

[0023] Next, the first trench 21, the second trench 31, and the third trench 41 will be described. As shown in FIG. 7, the first trench 21 has a first width W1. The second trench 31 has a second width W2. The third trench 41 has a third width W3. In detail, the first trench 21, the second trench 31, and the third trench 41 are trenches of the same width. The first width W1 is equal to the second width W2 and is also equal to the third width W3. On the other hand, the first trench 21, the second trench 31, and the third trench 41 may be trenches of different widths. That is, at least two of the first width W1, the second width W2, and the third width W3 are not equal. In this embodiment, the first width W1, the second width W2, and the third width W3 are each 10 microns (μm) to 5 millimeters (mm).

[0024] Moreover, the first surface 11 of the substrate 1 and the first trench 21 define a first height H1. The first surface 11 of the substrate 1 and the second trench 31 define a second height H2. The first surface 11 of the substrate 1 and the third trench 31 define a third height H3. In particular, the first trench 21, the second trench 31, and the third trench 41 are trenches of the same height. The first height H1 is equal to the second height H2 and is also equal to the third height H3. On the other hand, the first trench 21, the second trench 31, and the third trench 41 may be trenches of different heights. That is, at least two of the first height H1, the second height H2, and the third height H3 are not equal. In this embodiment, the first height H1, the second height H2, and the third height H3 are each 500 microns (μm) to 2000 microns (μm). In other words, the first height H1, the second height H2, and the third height H3 are the distances between the deepest points of the first trench 21, the second trench 31, and the third trench 41, respectively, and the first surface 11 of the substrate 1. The width distance of each trench and the height distance from the surface of the substrate 1 are intended to relieve stress against temperature changes in the substrate 1 during epitaxial growth.

[0025] Next, with reference to Fig. 3 to Fig. 6, several embodiments of the silicon substrate structure 1000 according to the present invention will be described. As shown in Fig. 3, the first trenches 21 formed on the second surface 12 of the substrate 1 are arranged in parallel to the first direction D1. The second trenches 31 formed on the second surface 12 of the substrate 1 are arranged in parallel to the second direction D2. The third trenches 41 formed on the second surface 12 of the substrate 1 are arranged in parallel to the third direction D3. The first trench 21, the second trench 31, and the third trench 31 are continuous trenches and extend to the outer periphery 13 and the secant line 14 of the substrate 1. The first trench 21, the second trench 31, and the third trench 41 form a triangular pattern that is interconnected. In another embodiment of the present invention, as shown in FIG. 4, the first trench 21, the second trench 31, and the third trench 31 are similarly arranged in the substrate 1 along the first direction D1, the second direction D2, and the third direction D3, respectively. The first trench 21, the second trench 31, and the third trench 31 are discontinuous and intermittent trenches, and are provided only near the periphery of the second surface 12 of the substrate 1. No trench is formed in the central region of the substrate 1. Note that, in another embodiment of the present invention, as shown in FIG. 5, the first trench 21, the second trench 31, and the third trench 31 are also discontinuous and intermittent trenches. The first trench 21, the second trench 31, and the third trench 31 are uniformly arranged in the substrate 1 along the first direction D1, the second direction D2, and the third direction D3, respectively. The first trench 21, the second trench 31, and the third trench 41 form a triangular pattern that is not connected to each other. In addition, in another embodiment of the present invention, as shown in FIG. 6, the first trench 21, the second trench 31, and the third trench 31 are also discontinuous and intermittent trenches. The intermittent first trench 21, the second trench 31, and the third trench 41 are connected to each other to form a closed triangular pattern. Triangular patterns of different sizes may overlap each other. Note that the first trench 21, the second trench 31, and the third trench 41 of the silicon substrate structure 1000 according to the present invention are formed based on corresponding lattice directions. The first trench 21 is formed based on a first direction D1. The second trench 31 is formed based on a second direction D2.The third trench 41 is formed based on the third direction D3. By forming the trenches in these three specific directions, the stress generated on the bottom surface of the substrate warped due to high temperature can be alleviated or eliminated. As shown in the embodiments of Figures 3 to 6, the position and number of the trenches can be changed according to actual needs, and are not limited thereto.

[0026] In this embodiment, the user may form the first trench 21, the second trench 31, and the third trench 41 by etching, laser cutting, scraping, etc., but the manufacturing method is not limited thereto. It should be noted that the trench density of the first trench 21, the second trench 31, and the third trench 41 located on the substrate 1 can be distributed according to the stress ratio of each part of the substrate 1. For example, the trenches may form a comprehensive or local pattern on the second surface 12 of the substrate 1. The patterns may be different in size, and may overlap or intersect. Also, trenches of different sizes may be used alternately.

[0027] As described above, the silicon substrate structure according to the present invention includes a substrate, a first groove, a second groove, and a third groove. The grooves are formed along the corresponding lattice directions. By designing the first trenches of the first groove, the second trenches of the second groove, and the third trenches of the third groove, the width of the trenches, and the thickness of the substrate after subtracting the depth of the trenches, the silicon substrate structure has a compression space for relaxing distortion. This suppresses the occurrence of cracks in the epitaxial crystal, and improves the uniformity of the epitaxial crystal and the manufacturing yield.

[0028] The above examples are for explaining the embodiments of the present invention and for explaining the characteristic configuration of the present invention. The present invention is not limited to the above examples. Modifications or equivalent arrangements that can be easily made by those skilled in the art are also within the scope of the present invention. The scope of protection of the rights of the present invention is based on the claims. [Explanation of symbols]

[0029] 1000 Silicon substrate structure 2000 Gallium nitride layer 1 Board 11 1st surface 12 Second surface 13 Outer surface 14 secant line section 2 First groove 21 Trench No. 1 3 2nd groove 31 Second Trench 4 Third groove 41 Trench No. 3 D1 1st direction D2 2nd direction D3 Third direction D4 4th direction θ1 1st angle θ2 2nd angle W1 1st width W2 Second width W3 3rd width H1 First height H2 Second height H3 3rd height

Claims

1. 1. A silicon substrate structure, comprising: a substrate having a first surface formed on one side of a silicon (111) lattice plane and a second surface formed on an opposite side of the silicon (111) lattice plane; a first groove provided on the second surface of the substrate along a first direction; A second groove is provided on the second surface of the substrate along a second direction; a third groove provided on the second surface of the substrate along a third direction; The first direction is defined as a direction from a silicon (111) lattice plane to a silicon (1-1-1) lattice plane, the second direction is defined as a direction from a silicon (-11-1) lattice plane to a silicon (1-11) lattice plane, and the third direction is defined as a crystal axis direction of silicon [1-10].

2. 2. The silicon substrate structure of claim 1, wherein the first direction forms a first angle with a fourth direction of a silicon (111) lattice plane, the second direction forms a second angle with the fourth direction of a silicon (111) lattice plane, the fourth direction is perpendicular to the third direction, and the first angle is substantially equal to the second angle.

3. 3. The silicon substrate structure of claim 2, wherein the first angle and the second angle are 35.26±3 degrees.

4. 2. The silicon substrate structure according to claim 1, wherein the first trench has a plurality of first trenches arranged in parallel to the first direction, the second trench has a plurality of second trenches arranged in parallel to the second direction, and the third trench has a plurality of third trenches arranged in parallel to the third direction.

5. 5. The silicon substrate structure according to claim 4, wherein any one of the first trench, the second trench, and the third trench is arranged continuously or discontinuously.

6. 5. The silicon substrate structure of claim 4, wherein the first trench has a first width, the second trench has a second width, and the third trench has a third width, the first width, the second width, and the third width being equal.

7. 7. The silicon substrate structure of claim 6, wherein the first width, the second width, and the third width are each between 10 microns and 5 millimeters.

8. 5. The silicon substrate structure of claim 4, wherein the substrate and the first trench define a first height, the substrate and the second trench define a second height, and the substrate and the third trench define a third height, the first height, the second height, and the third height being equal.

9. 9. The silicon substrate structure of claim 8, wherein the first height, the second height, and the third height are each between 500 microns and 2000 microns.

10. 2. The silicon substrate structure of claim 1, wherein the substrate has a perimeter and a secant that are connected together and define the substrate as a non-circular substrate.

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