KR102152710B1 - Substrate for growing semiconductor - Google Patents

Abstract

The present invention relates to a growth substrate, and more particularly, to a substrate for semiconductor growth. The present invention provides a substrate for semiconductor growth, comprising: an upper surface including a growth surface of a semiconductor; A lower surface having an area larger than that of the upper surface; A crack prevention surface extending from an end of the upper surface to an end of the lower surface with a slope; And a contact portion included in the lower surface and in contact with the substrate support portion.

Description

Substrate for growing semiconductor

The present invention relates to a growth substrate, and more particularly, to a substrate for semiconductor growth.

Nitride Compound Semiconductor, represented by gallium nitride (GaN), has high thermal stability and a wide band gap (0.8 to 6.2 eV), attracting much attention in the field of high-power electronic component device development including LEDs. come.

One of the reasons for this is that GaN is combined with other elements (indium (In), aluminum (Al), etc.), so that semiconductor layers emitting ultraviolet, blue, and green light can be manufactured, as well as mixed with phosphors. This is because it can be used as a light source for lighting that emits white light.

The nitride-based semiconductor layer is generally manufactured using a method such as metal-organic chemical vapor deposition (MOCVD), and as a substrate for growing it, sapphire, silicon carbide, gallium nitride, silicon, etc. It is mainly used.

In particular, silicon substrates are inexpensive compared to other substrates, are easy to make a diameter larger than 6 inches, and have high compatibility with existing silicon semiconductor process technologies and equipment, and thus have attracted much attention recently.

However, since the difference in lattice constant and coefficient of thermal expansion with GaN is larger than that of other substrates, and the elastic modulus is relatively small, it is difficult to increase the diameter of the substrate and to grow a high-quality film.

In particular, plastic deformation occurs on the silicon substrate due to stress applied as the nitride semiconductor thin film, which is a heterogeneous thin film, is grown on a silicon substrate exhibiting ductile characteristics at high temperatures, which causes the silicon substrate to become more fragile at room temperature. This becomes easier, and cracks may easily occur in the edges of the silicon substrate and the semiconductor film during growth or during cooling to room temperature.

Cracking phenomena such as slip of the substrate and crack of the thin film generated from the edge portion can be a major cause of easily damaging the substrate when a thermal or mechanical shock is applied in the subsequent process.

In addition, this phenomenon is inevitably worse when the diameter is larger than 6 inches, so preventing this is one of the things that must be overcome in order to activate the technology to grow a compound semiconductor containing gallium nitride on a large diameter silicon substrate. .

An object of the present invention is to provide a substrate for semiconductor growth capable of preventing defects in a semiconductor thin film when a semiconductor is grown on the substrate.

As a first aspect for achieving the above technical problem, the present invention provides a substrate for semiconductor growth, comprising: an upper surface including a growth surface of a semiconductor; A lower surface having an area larger than that of the upper surface; A crack prevention surface extending from an end of the upper surface to an end of the lower surface with a slope; And a contact portion included in the lower surface and in contact with the substrate support portion.

Here, a side surface extending downward from the crack prevention surface; And a lower inclined surface that has an inclination and continues from the side to the lower surface.

In this case, the crack prevention surface may have an area larger than that of the lower inclined surface.

Here, the contact surface may be located outside the growth surface.

In this case, the contact surface may be located outside the point projected toward the lower surface of the end of the growth surface.

Here, the contact surface may be located within a width of the crack prevention surface.

Here, the end of the crack prevention surface may be curved to lead to the lower surface.

Here, the area of the lower surface may be larger than the upper surface by at least an area of the contact surface.

Here, the substrate may be a silicon substrate for compound semiconductor growth.

As a second point of view for achieving the above technical problem, the present invention provides a substrate for semiconductor growth, comprising: a top surface including a growth surface of a semiconductor; A lower surface having an area larger than that of the upper surface; A crack prevention surface extending from an end of the upper surface to an end of the lower surface with a slope; A side extending downward from the crack prevention surface; A lower inclined surface connected with a slope from the side to the lower surface; And a contact portion included on the lower surface and in contact with the substrate support portion and positioned outside the growth surface.

The present invention has the following effects.

The substrate of the present invention can effectively prevent the cracking phenomenon such as slip and crack of the semiconductor thin film grown on the edge portion, and is suitable for growing a high-quality semiconductor thin film.

In addition, it is possible to prevent damage to the substrate due to thermal or mechanical shock that may occur during the semiconductor growth process.

In addition, since it is possible to grow a high-quality semiconductor only by a conventional substrate manufacturing process without an additional process or cleaning process, it is possible to reduce the causes of contamination of the thin film that may additionally occur during the growth of the thin film.

As mentioned above, a silicon substrate can be used for such a substrate, and since it is possible to grow high-quality nitride semiconductors using this substrate, it is suitable for the activation and mass production of a technology for growing gallium nitride semiconductors on a large-diameter silicon substrate. Do.

1 is a schematic diagram showing an end of an example of a substrate for semiconductor growth.
2 is a schematic diagram showing an end of another example of a substrate for semiconductor growth.
3 is a schematic diagram showing a first example of a state in which a substrate is mounted on a susceptor.
4 is a schematic diagram showing a second example of a state in which a substrate is mounted on a susceptor.
5 is a schematic diagram showing a third example of a state in which a substrate is mounted on a susceptor.
6 is a graph showing the degree of warpage of a substrate in a semiconductor growth chamber.
7 is a photograph showing a slip phenomenon during semiconductor growth.
8 is a photograph showing a crack phenomenon during semiconductor growth.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

While the present invention allows various modifications and variations, specific embodiments thereof are illustrated and shown in the drawings, and will be described in detail below. However, it is not intended to limit the present invention to the particular form disclosed, but rather the present invention encompasses all modifications, equivalents and substitutions consistent with the spirit of the present invention as defined by the claims.

When an element such as a layer, region or substrate is referred to as being “on” another component, it will be understood that it may exist directly on another element or there may be intermediate elements between them. .

Although terms such as first, second, etc. may be used to describe various elements, components, regions, layers and/or regions, these elements, components, regions, layers and/or regions It will be understood that it should not be limited by these terms.

1 is a schematic diagram showing an end of an example of a substrate for semiconductor growth.

As shown in FIG. 1, the substrate 100 for semiconductor growth may have an upper surface 110 including a growth surface of a semiconductor and a lower surface 120 having a larger area than the upper surface 110. Here, the semiconductor growth surface may occupy at least a portion of the upper surface 110.

In addition, the substrate 100 may have a crack prevention surface 130 extending from an end (border) of the upper surface 110 to an end side of the lower surface 120 with an inclination.

Here, it may further have a side surface 160 extending downward from the crack prevention surface 130 and a lower side inclined surface 150 extending from the side surface 160 to the lower surface 120 with a slope.

At this time, at least a portion of the lower surface 120 may include a contact portion 140 that contacts the substrate support portion 200 that supports the substrate 100 in the growth equipment for semiconductor growth. The substrate support 200 may be a part of a susceptor 201 (see FIG. 3) for heating the substrate 100.

That is, since the contact part 140 is a part that directly contacts the substrate support part 200 which is a part of the semiconductor growth equipment, the temperature deviation may be much greater than that of other parts of the substrate 100.

The contact part 140 may be located outside the growth surface. That is, the contact part 140 may be located at the end side of the upper surface 110 more than the point projected by the lower surface 120. Accordingly, the contact portion 140 may be located within the width A of the crack prevention surface 130.

In this case, the area of the lower surface 120 of the substrate 100 may be larger than the upper surface 110 by at least the area of the contact portion 140. Referring to FIG. 1, the width of the lower surface 120 may be greater than the width of the upper surface 110 by at least the width C of the contact portion 140.

Here, the substrate 100 may be a silicon substrate 100 for growing a compound semiconductor such as a nitride-based semiconductor. However, it is not limited thereto.

The crack prevention surface 130 mentioned above may have a larger area than the lower inclined surface 150. A thin film may not be grown or growth may be suppressed on the crack prevention surface 130 by a semiconductor growth process.

Accordingly, due to the crack prevention surface 130, a phenomenon such as a slip phenomenon occurring from the end (rim) side of the substrate 100 or a crack in the thin film may be prevented.

The crack prevention surface 130 may be inclined to have a certain angle θ with respect to the upper surface 110.

Due to the angle θ of the crack prevention surface 130, the crack prevention surface 130 may have a different direction from the growth surface (hereinafter, described as the upper surface 110 for convenience), and the upper surface 110 is < In the case of a crystal plane in the 111> direction, it may be a <100> direction or a <110> direction that is a different crystal plane. It may have any other non-crystalline surface.

Since the growth rate of the semiconductor thin film through the crack prevention surface 130 is significantly slower than that of the upper surface 110 or growth may be completely blocked, the unevenness of the temperature distribution is the largest, and the semiconductor thin film and the substrate 100 It is possible to prevent the crack of the edge portion of the substrate 100, which is the most severely deformed by the stress therebetween.

In addition, the width (A) of the crack prevention surface 130 in a direction parallel to the upper surface 110 is sufficient to prevent cracks in the substrate 100 and the semiconductor thin film grown on the substrate 100 However, it is desirable to make it more than the minimum length.

The width A of the crack prevention surface 130 is preferably set to be approximately 1 mm or more and 30 mm or less. More specifically, it is advantageous that the width A of the crack prevention surface 130 is greater than the distance B between the end portion of the substrate 100 and the contact portion 140. The width C of the contact part 140 may be narrower than the width A of the crack prevention surface 130.

This is because the boundary between the upper surface 110 and the crack prevention surface 130 by the width (A) of the crack prevention surface 130 than the substrate 100 and the contact part 150 is located further inside from the end of the substrate 100 Means.

That is, at the end of the substrate 100, the temperature difference between the other portion of the substrate 100 and the contact portion 140 is locally very high, which may cause the uneven thickness of the grown thin film, which occurs during the growth of the semiconductor thin film. Since it becomes the starting point of most slips and cracks, it is possible to block the growth of the thin film on the upper part of the contact part 140 through the crack prevention surface 130.

In addition, the width A of the crack prevention surface 130 and the angle θ of the crack prevention surface 130 are determined in an appropriate range according to the thickness D of the substrate 100, as an approximate range, The width A of the crack prevention surface 130 is preferably set to 1 mm or more and 30 mm or less.

And the angle (θ) of the crack prevention surface 130 may be less than about 45° when the thickness (D) of the substrate 100 is 1 mm, and less than about 56° when the thickness (D) is 1.5 mm And, when the thickness (D) is 3 mm, it is preferably set to about 71° or less.

2 is a schematic diagram showing an end of another example of a substrate for semiconductor growth.

As shown in FIG. 2, the end of the crack prevention surface 130 may lead to the lower surface 120 through the curved surface 161.

Compared with the case of FIG. 1, the substrate 100 has a contact portion 141 having a larger width E, and accordingly, the area of the lower surface 120 may be wider than that of FIG. 1.

In addition, the width A'of the crack prevention surface 130 may also be larger, and an area corresponding thereto may also be wider.

Other parts that are not described may be equally applied to the items described with reference to FIG. 1.

The manufacturing process of growing a gallium nitride-based semiconductor thin film using a conventional silicon substrate as a growth substrate has many advantages. This is because a silicon substrate is much cheaper than a sapphire, silicon carbide, and gallium nitride substrate, and a silicon semiconductor-based technology that has already accumulated many technologies is applied, or it is highly compatible with these technologies and equipment for the same.

However, the difference between the lattice constant and the coefficient of thermal expansion between the gallium nitride and the silicon semiconductor is about 17% and 70%, respectively, which is larger than the difference with the substrate of other materials such as sapphire, silicon carbide, and gallium nitride substrate, and the elastic modulus is relatively small. Therefore, there is a greater possibility of cracking in the semiconductor thin film.

Such a crack phenomenon can be represented by a slip phenomenon of a substrate or a crack phenomenon of a thin film, and it is common to start mostly at the edge of the substrate and the thin film, and this may occur more often when the substrate is made large to 6 inches or more.

The slip phenomenon in the case of growing a semiconductor thin film on a silicon substrate refers to a phenomenon in which excessive thermal stress due to temperature variation within the substrate shifts the crystal plane of the silicon substrate, in other words, it can be seen as an example of plastic modification due to thermal stress. .

The root cause of this is the unevenness of severe temperature distribution in the process of heating the substrate in the high temperature chamber during growth, centrifugal force due to high speed rotation of the susceptor including the substrate, and mechanical strength related to the doping concentration of the substrate. to be.

In addition, the edge cracking phenomenon of the thin film may also be a form of deformation due to stress and elasticity limits between the grown semiconductor thin film and the silicon substrate. This can be prevented by controlling the stress between heterogeneous materials, but this may not be a fundamental solution because it is necessary to sacrifice the growth thickness or film quality of the thin film to some extent.

Temperature non-uniformity within the substrate, which is the largest cause of the cracking phenomenon, is strongly related to the structure of the susceptor 201 on which the substrate 100 is mounted, as shown in FIGS. 3 to 5.

The light emitting diode structure based on gallium nitride is formed by sequentially growing a buffer layer, an undoped gallium nitride layer, an n-type gallium nitride (n-GaN) layer, a light emitting layer, and a p-type gallium nitride layer on the silicon substrate 100 (Fig. Not).

In particular, in order to grow an n-type gallium nitride (n-GaN) layer, it is common to doping with silicon impurities, and the n-GaN layer grown in this process is subjected to excessive tensile stress, in this case, as shown in FIG. , The silicon substrate 100 is deformed into a convex shape in the high temperature chamber. At this time, the lower surface 202 of the susceptor 201 is a flat case.

Such a bending phenomenon of the substrate 100 may cause a non-uniform gap between the substrate 100 and the susceptor 201, which may cause a temperature deviation of the concentric distribution in the substrate 100, and the light emitting layer to be grown afterwards It can lead to an uneven composition distribution phenomenon.

Therefore, in order to reduce the temperature variation of the concentric distribution due to the bending of the substrate 100 during growth of the light emitting layer, as shown in FIG. 4, the lower surface 203 of the susceptor 201 may be processed and used in a convex shape.

For this reason, as shown in FIG. 5, when the buffer and the gallium nitride layer are grown at the initial stage of growth, the silicon substrate 100 may additionally bend in a convex downward direction.

In other words, in the process of heating the temperature in the chamber to 1,000°C or higher for initial semiconductor growth, the gap between the lower surface 204 of the susceptor 201 and the lower surface 204 in which the central portion of the silicon substrate 100 is convex compared to the edge is close.

This is because when the substrate 100 is mounted on the susceptor 201, the substrate 100 comes into contact with the substrate support part 200, so the rate of temperature increase in this part is inevitably fast. Therefore, the center of the substrate 100 The temperature distribution in the form of a concentric circle with high temperature is shown.

The temperature distribution in a concentric circle shape during the heating process of the substrate 100 may cause the deformation of the substrate 100 as shown in FIGS. 4 and 5, and this may cause the largest deformation at the edge of the substrate 100. There is.

6 is a graph showing the degree of warpage of the substrate in the semiconductor growth chamber, showing that it is deformed into a convex downward shape initially and a convex upward shape after the n-GaN growth process.

As shown in FIG. 6, it is shown that the degree of wafer warpage can vary from about -60 to +80 micrometers in the case of a 6-inch substrate, and from -120 to +150 micrometers in the case of an 8-inch substrate.

7 and 8 show micrographs of a slip phenomenon and a crack phenomenon that may occur during initial growth of a semiconductor, respectively.

As shown in FIG. 7, when a semiconductor is grown on a silicon substrate, a slip phenomenon, which is a phenomenon in which the silicon atomic planes slide with each other, may occur due to a shear force generated by bending of the silicon substrate and excessive temperature deviation within the substrate.

In addition, as shown in FIG. 8, a crack phenomenon may occur due to the same cause, which mainly occurs on the edge side.

In this way, when a gallium nitride-based semiconductor thin film is grown on the silicon semiconductor substrate 100, a phenomenon such as a crack phenomenon may continue to occur even when the slip phenomenon is overcome.

As described above, such a crack phenomenon may mainly occur at the edge (end) of the substrate.

Accordingly, as described with reference to FIGS. 1 and 2, the crack prevention surface 130 is configured on the edge side of the substrate 100, and further, in consideration of the contact portion 140 with the substrate support part 200 of the susceptor. By configuring the ends of the substrate 100 by controlling the areas of the upper and lower surfaces 110 and 120, the above-described cracking phenomenon can be prevented.

That is, such a substrate 100 can effectively prevent a crack phenomenon such as slip and crack of the semiconductor thin film grown on the edge portion, and is suitable for growing a high-quality semiconductor thin film.

In addition, it is possible to prevent damage to the substrate 100 due to thermal or mechanical shock that may occur during the semiconductor growth process.

In addition, since it is possible to grow a high-quality semiconductor only by a conventional substrate manufacturing process without an additional process or cleaning process, it is possible to reduce the causes of contamination of the thin film that may additionally occur during the growth of the thin film.

As mentioned above, the substrate 100 can use a silicon substrate, and since it is possible to grow a high-quality nitride semiconductor using the substrate 100, a nitride-based semiconductor is grown on the large-diameter silicon substrate 100. It is suitable for the activation and mass production of technology.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are only presented specific examples to aid understanding, and are not intended to limit the scope of the present invention. It is obvious to those of ordinary skill in the art that other modifications based on the technical idea of the present invention may be implemented in addition to the embodiments disclosed herein.

100: substrate 110: upper surface
120: lower surface 130: crack prevention surface
140: contact portion 150: lower slope
160: side 200: substrate support
201: susceptor

Claims (10)

In the substrate for semiconductor growth,
A top surface including a growth surface of a semiconductor;
A lower surface having an area larger than that of the upper surface;
A crack prevention surface extending from an end of the upper surface to an end of the lower surface with an inclination, and preventing at least one of a slip phenomenon or a crack of a thin film occurring from an end of the substrate; And
Included in the lower surface and including a contact portion in contact with the substrate support,
At least a portion of the upper portion of the contact portion is a substrate for semiconductor growth, characterized in that the crack prevention surface. The method of claim 1, further comprising: a side surface extending downward from the crack prevention surface; And a lower inclined surface extending from the side surface to the lower surface. The substrate for semiconductor growth according to claim 2, wherein the crack prevention surface has an area larger than that of the lower inclined surface. The substrate according to claim 1, wherein an end portion of the contact portion is located outside a point projected from a point where an end portion of the growth surface is projected toward the lower surface. delete The substrate according to claim 1, wherein the contact portion is located within a width of the crack prevention surface. The substrate for semiconductor growth according to claim 1, wherein an end portion of the crack prevention surface is curved to the lower surface. The substrate for semiconductor growth according to claim 1, wherein an area of the lower surface is larger than the upper surface by at least an area of the contact portion. The substrate for semiconductor growth according to claim 1, wherein the substrate is a silicon substrate for compound semiconductor growth. In the substrate for semiconductor growth,
A top surface including a growth surface of a semiconductor;
A lower surface having an area larger than that of the upper surface;
A crack prevention surface extending from an end of the upper surface to an end of the lower surface with a slope;
A side extending downward from the crack prevention surface;
A lower inclined surface connected with a slope from the side to the lower surface; And
Consisting of including a contact portion included in the lower surface and in contact with the substrate support,
The substrate for semiconductor growth, characterized in that the end of the contact portion is located outside a point where the end of the growth surface is projected toward the lower surface.

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