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 to relieve stress during epitaxial growth. [Background technology]

[0002] Epitaxial technology plays an important role in semiconductor manufacturing and optoelectronics. It primarily uses two materials: silicon carbide and gallium nitride. The silicon substrate structure formed by epitaxial growth of a gallium nitride layer is an essential base material for semiconductor devices. From a manufacturing cost perspective, the current mainstream gallium nitride substrate is silicon-based gallium nitride technology, in which gallium nitride epitaxial crystals are grown on a silicon substrate. This technology is a heteroepitaxial technology in the semiconductor industry. As the epitaxial crystal grows, the gallium nitride layer becomes thicker due to high-temperature expansion, and the silicon substrate also expands with increasing temperature. The deformation amount underneath the silicon substrate also increases with the thickness of the gallium nitride epitaxial layer, gradually increasing the tensile strain of the substrate. When the thickness of the gallium nitride film exceeds a certain threshold, the compressive stress underneath is transferred in other directions, and the compression phenomenon becomes more pronounced in the lower lattice. It should be noted that 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 central bowing of the silicon substrate, which adversely affects epitaxial uniformity.

[0003] However, due to the lattice mismatch and differences in thermal expansion coefficients between two dissimilar materials, strain easily accumulates between them. During epitaxial growth, deformation occurs as the temperature rises, and as the temperature drops, stress is released unevenly, adversely affecting the quality of the epitaxial film and causing cracks. Methods for improving epitaxial technology using dissimilar materials include patterning the surface of the epitaxial substrate, creating grooves on the surface of the epitaxial substrate and filling them with stress-compensating materials, and using a stress-absorbing cushion layer structure. All of these techniques require better epitaxial materials to improve substrate warpage at high temperatures, ensure a uniform heating process, and ensure uniform stress release 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] An object of the present invention is to provide a silicon substrate structure that enables stable epitaxial crystal growth. The present invention provides a substrate structure with grooves formed on the underside based on three specific lattice directions. As the temperature increases, the lower silicon lattice is compressed, allowing for stable growth of the epitaxial layer on the substrate. The groove spaces can compensate for deformation due to substrate warpage and relieve stress accumulated due to the deformation. Meanwhile, as the temperature decreases, the silicon lattice that was compressed at high temperatures gradually concentrates, and the cooled gallium nitride layer also causes strain in the silicon substrate. However, the grooves in the substrate can reduce the amount of deformation and uniformly release the strain. Therefore, the use of the silicon substrate structure according to the present invention can reduce cracking and improve uniformity during the epitaxial process, thereby improving the production yield of epitaxial films.

[0006] 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 the direction from the silicon (111) lattice plane to the silicon (1-1-1) lattice plane. The second direction is defined as the direction from the silicon (-11-1) lattice plane to the silicon (1-11) lattice plane. The third direction is defined as the crystallographic axis direction of silicon [1-10].

[0007] In an embodiment of the present 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 groove has a plurality of first trenches arranged in a row parallel to the first direction, the second groove has a plurality of second trenches arranged in a row parallel to the second direction, and the third groove has a plurality of third trenches arranged in a row 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 present 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 present 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 present invention, the substrate and the first trench define a first height, the substrate and the second trench define a second height, the substrate and the third trench define a third height, and 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 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 explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing a silicon substrate structure and a gallium nitride layer according to an embodiment of the present invention; [Figure 2] 1 is a top view showing a silicon substrate structure according to an embodiment of the present invention; [Figure 3] 1 is a 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; [Figure 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 INVENTION

[0018] The present invention will be described below through examples. Note that the examples of the present invention are merely 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 intended to explain the present invention, but does not limit the present invention. Note that components not directly related to the present invention are omitted and not shown in the embodiments and drawings. The dimensional relationships between the components in the drawings are intended to facilitate understanding and do not limit the actual dimensions.

[0019] The following description will be made with reference to FIGS. 1 and 2. FIG. 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. FIG. 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 secant 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 secant 14 are both outer edges of the substrate 1. The outer periphery 13 and the secant 14 are connected to each other, defining the substrate 1 as a non-circular substrate. Note that in this embodiment, the secant 14 is located at the bottom end of the substrate 1, but the position of the secant 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]. There is also a direction on the substrate 1 that is perpendicular to the third direction D3, 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. Specifically, 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 equal to the third width W3. Alternatively, 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 unequal. In this embodiment, the first width W1, the second width W2, and the third width W3 are each between 10 microns (μm) and 5 millimeters (mm).

[0024] Furthermore, 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. Specifically, 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 equal to the third height H3. Alternatively, 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 between 500 microns (μm) and 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 set to relieve stress caused by temperature changes in the substrate 1 during epitaxial growth.

[0025] Next, with reference to FIGS. 3 to 6, several embodiments of a silicon substrate structure 1000 according to the present invention will be described. As shown in FIG. 3, first trenches 21 formed in the second surface 12 of the substrate 1 are arranged parallel to a first direction D1. Second trenches 31 formed in the second surface 12 of the substrate 1 are arranged parallel to a second direction D2. Third trenches 41 formed in the second surface 12 of the substrate 1 are arranged parallel to a third direction D3. The first trench 21, the second trench 31, and the third trench 31 are continuous trenches that 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 trenches are 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 one another. 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 in the third direction D3. By forming the trenches in these three specific directions, 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 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, or the like, but the manufacturing method is not limited thereto. The trench density of the first trench 21, the second trench 31, and the third trench 41 located in the substrate 1 may be distributed according to the stress ratio of each portion of the substrate 1. For example, the trenches may form a global or local pattern on the second surface 12 of the substrate 1. The patterns may be of different sizes, and may overlap or intersect. Alternatively, trenches of different sizes may be alternately used.

[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. The design of the first trenches of the first groove, the second trenches of the second groove, and the third trenches of the third groove, as well as the trench width and substrate thickness after subtracting the trench depth, allows the silicon substrate structure to have a compression space for strain relief. This effectively prevents cracks from occurring in the epitaxial crystal, improving the uniformity of the epitaxial crystal and the manufacturing yield.

[0028] The above examples are intended to explain embodiments of the present invention and to explain the characteristic configurations 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 First Trench 3 2nd groove 31 Second Trench 4 Third groove 41 Third Trench 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 Third height

Claims

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 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]; 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; The silicon substrate structure, wherein the first angle and the second angle are 35.26±3 degrees.

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

3. 3. The silicon substrate structure according to claim 2, wherein any one of the first trench, the second trench, and the third trench is arranged continuously or discontinuously.

4. 3. The silicon substrate structure of claim 2, wherein 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.

5. 5. The silicon substrate structure of claim 4, wherein the first width, the second width, and the third width are each between 10 microns and 5 millimeters.

6. 3. The silicon substrate structure of claim 2, 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, and the first height, the second height, and the third height are equal.

7. 7. The silicon substrate structure of claim 6, wherein the first height, the second height, and the third height are each between 500 microns and 2000 microns.

8. 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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