KR20170033118A - Method of manufacturing nitride semiconductor substrates for control bowing by using polishing technique of nitride semiconductor substrates - Google Patents

Method of manufacturing nitride semiconductor substrates for control bowing by using polishing technique of nitride semiconductor substrates Download PDF

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KR20170033118A
KR20170033118A KR1020150131036A KR20150131036A KR20170033118A KR 20170033118 A KR20170033118 A KR 20170033118A KR 1020150131036 A KR1020150131036 A KR 1020150131036A KR 20150131036 A KR20150131036 A KR 20150131036A KR 20170033118 A KR20170033118 A KR 20170033118A
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nitride semiconductor
semiconductor substrate
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이현재
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주식회사 루미스탈
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Abstract

The present invention relates to a method for manufacturing a nitride semiconductor substrate for controlling bending through surface processing. The present invention adjusts bending which is commonly generated on a nitride semiconductor substrate, in which the difference of defects occurs, through surface processing of the substrate, thereby minimizing bending.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a nitride semiconductor substrate,

The present invention relates to a method of manufacturing a nitride semiconductor substrate that controls warpage through surface processing, and more particularly, to a method of manufacturing a nitride semiconductor substrate by controlling a bow, which is often generated in a nitride semiconductor substrate with a large difference in defects, And a method of manufacturing the removed nitride semiconductor substrate.

Semiconductor materials such as group III nitride semiconductors such as aluminum nitride (AlN), gallium nitride (GaN), indium nitride (InN), indium gallium nitride (InGaN), and gallium aluminum nitride (GaAlN) may be used in light emitting diodes (LEDs) LD), and other electronic devices.

In general, a nitride semiconductor is grown on a different substrate by a method such as MOCVD (Metal Organic Chemical Vapor Deposition) or HVPE (Hydride Vapor Phase Epitaxy).

(GaN) wafers, which are the most commonly used nitride semiconductors, may be fabricated using a variety of materials including sapphire (Al 2 O 3 ), silicon carbide (SiC), gallium arsenide (GaAs) A gallium nitride (GaN) layer is grown on a substrate, and then the grown gallium nitride layer is separated to produce a gallium nitride wafer.

However, since the nitride semiconductor material such as gallium nitride grown in this way generates a large stress due to the difference in lattice constant and thermal expansion coefficient from the different substrate, cracks are generated on the nitride semiconductor layer Cracks or bowing are caused in the nitride semiconductor substrate, thereby deteriorating the quality of the substrate when the nitride semiconductor is separated into the base substrate.

In particular, warpage of the semiconductor substrate causes various problems. For the device manufacturing, the temperature difference between the bottom surface and the outer surface or the difference in the gas distribution during the growth of the device causes non-uniformity of the device, .

Various techniques have been proposed to minimize the internal stress of the grown nitride semiconductor by applying various buffer layer structures on the base substrate, which is a heterogeneous substrate for growth, in manufacturing the nitride semiconductor substrate.

As a currently proposed technique, there is a method of reducing the stress by inserting a large number of voids at the interface between the base substrate and the grown nitride semiconductor by inserting a metal layer such as silicon oxide (SiO 2 ) patterning or titanium (Ti) .

However, these methods have a disadvantage in that it is difficult to completely eliminate the warpage of the substrate because the nitride semiconductor grown at a high temperature can not completely relieve a large stress of about 600 MPa occurring at the interface while cooling the temperature to room temperature.

In addition, since a number of complicated processes are required to reduce the warpage of the substrate, the production cost of the product is increased.

Patent Registration No. 10-0680670

SUMMARY OF THE INVENTION The present invention is directed to solve the problems of the prior art as described above, and propose a bending control method for eliminating or minimizing bending generated in a substrate during a manufacturing process of a nitride semiconductor substrate through a simple process.

In particular, the present invention proposes a method for improving quality and manufacturing cost of a nitride semiconductor substrate by eliminating or minimizing warping of a nitride semiconductor substrate caused by stress due to a difference in defect density between a plurality of nitride semiconductor layers.

According to an aspect of the present invention, there is provided a method of fabricating a nitride semiconductor substrate, the method including: preparing a nitride semiconductor substrate having at least two or more nitride semiconductor layers sequentially stacked to form a bow, A substrate preparation step; Determining a bending direction and a bending magnitude of the nitride semiconductor substrate to determine a machining surface of the nitride semiconductor substrate along the bending direction and calculating a surface machining amount based on the bending direction and the bending magnitude, A machining condition setting step of setting a machining condition according to the surface machining amount; And a surface machining step of controlling the warpage of the nitride semiconductor substrate by processing the machined surface of the nitride semiconductor substrate according to the machining conditions.

Preferably, the machining condition setting step includes determining a bending direction of the concave or convex based on the upper surface of the nitride semiconductor substrate, measuring the size between the highest height and the lowest height on the surface of the nitride semiconductor substrate, It is possible to grasp the size of the image.

More preferably, in the machining condition setting step, the upper surface of the nitride semiconductor substrate is determined as the machined surface when the warping direction is concave, and when the warping direction is convex, the lower surface of the nitride semiconductor substrate is machined And the surface machining amount is calculated by the following formula 1,

[Formula 1]

Figure pat00001

Here, W is the surface machining amount, T is the thickness ratio between the uppermost layer and the lowermost layer in the nitride semiconductor layer, B is the bending amount, and? Can be a predetermined correction constant.

The semiconductor substrate preparation step may include: forming a buffer layer on the base substrate and sequentially stacking two or more nitride semiconductor layers on the buffer layer; Removing the base substrate; And removing the buffer layer to prepare a vias semiconductor substrate composed of two or more nitride semiconductor layers.

For example, the semiconductor substrate preparation step may include preparing a nitride semiconductor substrate in which a second GaN layer is stacked on the first GaN layer, and the processing condition setting step may include a step of, when the bending direction is concave, The upper surface of the layer is determined as a machined surface, and the surface machining amount is calculated by the following formula (2)

[Formula 2]

Figure pat00002

Here, W1 is a surface processing amount of the second GaN layer, T1 is a value obtained by dividing the thickness of the second GaN layer by the thickness of the first GaN layer, B1 is a maximum height on the upper surface of the second GaN layer And the minimum height, and α1 may be a correction constant set at the time of surface processing of the second GaN layer.

As another example, in the semiconductor substrate preparation step, a nitride semiconductor substrate in which a second GaN layer is stacked on the first GaN layer is prepared, and in the case where the bending direction is convex, 1 GaN layer is determined as a machined surface, and the surface machining amount is calculated by the following expression (3)

[Formula 3]

Figure pat00003

Wherein W2 is a surface machining amount of the first GaN layer, T2 is a thickness of the first GaN layer divided by a thickness of the second GaN layer, B2 is a height of a bottom surface of the first GaN layer And the minimum height, and the alpha 2 may be a correction constant set at the surface processing of the first GaN layer.

Further, in the surface machining step, the machined surface may be sequentially subjected to a grinding process and a polishing process in accordance with the machining conditions to control the bending magnitude of the nitride semiconductor substrate to 20 μm or less .

Further, the surface machining step may further include a lapping process after the grinding process, and a CMP (Chemical Mechanical Polishing) process after the polishing process.

According to the present invention, the residual warpage of the nitride semiconductor substrate manufactured using the heterojunction substrate as a substrate for growth can be removed or minimized through a simple surface processing process, thereby reducing quality and manufacturing cost of the nitride semiconductor substrate.

Particularly, the nitride semiconductor substrate having a defect difference of 10 times or more between the plurality of nitride semiconductor layers is surface-processed in accordance with the present invention under the processing conditions suitable for the bending characteristics, whereby the residual warpage of the nitride semiconductor substrate can be controlled to 20 μm or less.

1 shows a cross section of a nitride semiconductor substrate,
2 shows the principle of residual bending of the nitride semiconductor substrate,
Fig. 3 shows the principle of controlling warping of a nitride semiconductor substrate in which concave warpage remains in the present invention,
FIG. 4 shows the principle of controlling warpage of a nitride semiconductor substrate in which convex bending remains in the present invention,
Fig. 5 shows experimental results of warpage control using the surface processing according to the present invention for a gallium nitride semiconductor substrate in which concave warpage remains,
FIG. 6 shows experimental results of performing warpage control on the gallium nitride semiconductor substrate in which convex warpage remains by using the surface processing according to the present invention,
Figure 7 shows a flow diagram of an embodiment of a method of fabricating a nitride semiconductor substrate to control warping through surface processing according to the present invention,
8 shows a configuration diagram of an embodiment of a warpage control apparatus for performing a method of manufacturing a nitride semiconductor substrate for controlling deflection through surface processing according to the present invention,
9 shows a process diagram for a first embodiment of a method of manufacturing a nitride semiconductor substrate for controlling deflection through surface processing according to the present invention,
Fig. 10 shows a process diagram for a second embodiment of a method of manufacturing a nitride semiconductor substrate for controlling deflection through surface processing according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

First, the terminology used in the present application is used only to describe a specific embodiment, and is not intended to limit the present invention, and the singular expressions may include plural expressions unless the context clearly indicates otherwise. Also, in this application, the terms "comprise", "having", and the like are intended to specify that there are stated features, integers, steps, operations, elements, parts or combinations thereof, But do not preclude the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The present invention relates to a method of manufacturing a nitride semiconductor substrate that improves quality through surface processing of a nitride semiconductor substrate, wherein residual bending of the nitride semiconductor substrate manufactured by using the heterojunction substrate as a growth substrate is removed by using a surface processing technique after growth And reducing the manufacturing cost of the nitride semiconductor substrate.

1 shows a cross section of a nitride semiconductor substrate. In FIG. 1 (a), a buffer layer 50 is formed on a sapphire substrate 10, which is a growth substrate, by using a HVPE (Hydride Vapor Phase Epitaxy) The first gallium nitride layer 110 and the second gallium nitride layer 150 having a lower defect density than the first gallium nitride layer 110 are successively grown.

1 (b) shows a GaN layer grown to a thickness of 360 m with the structure shown in FIG. 1 (a), separating the sapphire substrate from the gallium nitride layer, and then measuring the SEM (electron microscope) and Cathod-Luminescence ). Fig.

In FIG. 1 (b), a clean cross section is observed in the SEM photograph, but in the CL image of the same position, not only various types of defects but also three different layers depending on growth conditions are observed.

First, a buffer layer having a thickness of about 10 탆 or less is grown in the lowest layer, and a first GaN layer having a 3D (3-Dimensional) structure is grown to have a thickness of 170 탆 in order to reduce the residual stress of the gallium nitride layer. And a high-quality second GaN layer having a 2D (2-Dimensional) structure is grown on the upper portion to a thickness of about 180 탆.

Such a nitride semiconductor layer structure is known to show a defect difference of about 10 to 100 times or more between the upper layer and the lower layer.

When a nitride semiconductor layer having a thickness of 200 탆 or more is grown using sapphire or a silicon substrate, which is a dissimilar substrate, the buffer layer, the first GaN layer, and the second GaN layer as shown in FIG. 1 (a) The crystal quality and the growth technique for stress relaxation cause some warpage to remain on the substrate after removing the growth substrate.

In the case of a substrate having an approximate size of 4 inches or less, the degree of warpage may remain in the range of 50 to 400 占 퐉. The presence of such a large warpage has a problem in that it becomes difficult to manufacture a device by utilizing a nitride semiconductor substrate .

The present invention proposes a method of eliminating or minimizing the residual warpage of the nitride semiconductor substrate. Hereinafter, the concept of the present invention will be described, and then the residual warpage of the nitride semiconductor substrate is controlled according to the present invention, Hereinafter, the method will be described with reference to the embodiments.

FIG. 2 shows the principle of residual bending of the nitride semiconductor substrate. The residual bending of the nitride semiconductor substrate will be described with reference to FIG.

When a first GaN layer having a relatively high defect density and a second GaN having a relatively low defect density are sequentially stacked and formed, deflection occurs due to a difference in defect density. When a first GaN layer having a relatively high defect density is formed, A compressive stress is generated in the first GaN layer and a tensile stress is generated in the second GaN layer having a relatively low defect density.

2 (a), when the tensile stress Ft generated in the second GaN layer 150a is larger than the compressive stress Fc generated in the first GaN layer 110a, the tensile stress Ft causes concave warpage And remains on the nitride semiconductor substrate.

2 (b), when the compressive stress Fc generated in the first GaN layer 110b is larger than the tensile stress Ft generated in the second GaN layer 150b, the convex bending due to the compressive stress Fc causes the nitride And remains on the semiconductor substrate.

Considering the principle of causing residual bending of the nitride semiconductor substrate, the present invention judges that it is possible to control the residual bending on the nitride semiconductor substrate by controlling the magnitude of the stress between the stresses causing the residual bending. A method of fabricating a nitride semiconductor substrate capable of removing or minimizing the residual warpage of the nitride semiconductor substrate has been derived based on the results of various experiments for controlling the nitride semiconductor substrate.

The residual bending direction of the nitride semiconductor substrate can be divided into a concave warping in which the upper surface of the nitride semiconductor substrate is concave and a convex warping in which the upper surface of the nitride semiconductor substrate is convexly bent.

First, with reference to the principle of control of the warping of the nitride semiconductor substrate in which the concave warping remains in the present invention shown in Fig. 3, with reference to the concave warping direction of the residual warping.

When the residual warpage of the nitride semiconductor substrate exists in the concave and bending direction, the tensile stress Ft of the second GaN layer 150a is relatively larger than the compressive stress Fc of the first GaN layer 110a, The concave warpage of the nitride semiconductor substrate is reduced or eliminated by processing the surface of the second GaN layer 150a in order to control the concave warp caused by the tensile stress Ft of the first GaN layer 150a.

That is, by reducing the tensile stress Ft of the second GaN layer 150a through surface processing of the second GaN layer 150a, the tensile stress Ft of the second GaN layer 150a and the compressive stress of the first GaN layer 110a Fc of the first GaN layer 250a and the second GaN layer 250a of the second GaN layer 250a can be obtained by balancing the forces of the first GaN layer 210a and the second GaN layer 250a.

Next, with reference to the convex bending direction of the residual bending, the principle of controlling the bending of the nitride semiconductor substrate in which the convex bending remains in the present invention shown in Fig. 4 will be described.

When the residual warpage of the nitride semiconductor substrate exists in the convex bending direction, since the compressive stress Fc of the first GaN layer 110b is relatively larger than the tensile stress Ft of the second GaN layer 150b, The convex bending of the nitride semiconductor substrate is reduced or removed by processing the surface of the first GaN layer 110b to control the convex bending caused by the compressive stress Fc of the first semiconductor substrate 110b.

That is, by reducing the compressive stress Fc of the first GaN layer 110b through surface processing of the first GaN layer 110b, the compressive stress Fc of the first GaN layer 110b and the tensile stress Fc of the second GaN layer 150b Ft of the first GaN layer 250a and the second GaN layer 250b with a similar balance in terms of force balance so as to obtain a nitride semiconductor substrate of a first GaN layer 210b and a second GaN layer 250b whose deflection is eliminated or minimized according to the stress balance.

3 and 4, in order to control the residual warpage of the nitride semiconductor substrate, the conditions of the surface processing are more specifically described. The magnitude of the stress causing the residual warpage of the nitride semiconductor substrate is related to the thickness of each nitride semiconductor layer As the thickness of the nitride semiconductor layer is relatively thicker than the thickness of the other nitride semiconductor layers, a larger stress is generated, and the degree of warpage is different depending on the thickness ratio of the first GaN layer and the second GaN layer.

Therefore, in the present invention, the conditions of the surface processing can be set so as to be proportional to the thickness ratio of the first GaN layer and the second GaN layer.

In addition, since the stress of either the first GaN layer or the second GaN layer is relatively large as the residual warpage degree of the nitride semiconductor substrate is larger, in the present invention, in accordance with the residual bending magnitude of the nitride semiconductor substrate, Can be set.

The following formula 1 can be derived by integrating the surface processing conditions for controlling the warpage of the nitride semiconductor substrate. By processing the surface in the bending direction with the surface processing amount calculated by applying the following formula 1, The warpage control of the semiconductor substrate becomes possible.

[Formula 1]

Figure pat00004

Wherein W is a surface machining amount, T is a thickness ratio between the first GaN layer and the second GaN layer, B is a bending magnitude, and? Is a predetermined correction constant.

Although the semiconductor layer of the GaN layer has been described above as an example for convenience of explanation, the present invention is not limited to the gallium nitride semiconductor substrate but may be applied to a nitride semiconductor substrate including various Group III nitride semiconductor layers such as aluminum nitride (AlN). Further, although the first and second GaN layers are described as two semiconductor layers, the present invention may be applied to control the warping of a plurality of sequentially stacked nitride semiconductor layers depending on circumstances.

That is, when the present invention is extended to a method of controlling the warpage of a nitride semiconductor substrate composed of a plurality of nitride semiconductor layers, in the above-mentioned formula 1, T may be a thickness ratio of the uppermost layer and the lowermost layer of the nitride semiconductor layer, The above may be set according to the direction of warping, the type of the nitride semiconductor layer, and the like.

According to the principle of the present invention as described above, the residual warpage is controlled on the nitride semiconductor substrate in which various deflections remain, and as a result, the experimental results shown in FIGS. 5 and 6 are obtained.

FIG. 5 shows the results of experiments in which warpage control is performed by applying the principle of surface processing according to the present invention to a gallium nitride semiconductor substrate in which concave and convex defects remain. As shown in FIG. 5 (a) 1 GaN layer 110a and the second GaN layer 150a was surface-processed according to the principle of the present invention. As a result, the bending magnitude of the gallium nitride semiconductor substrate shown in FIG. 5 (b) The experimental results were obtained.

First, a buffer layer is grown to a thickness of about 10 mu m on a sapphire base substrate, a first GaN layer 110a and a second GaN layer 150a are sequentially grown on the buffer layer, the base substrate is removed, A buffer layer was removed by an etching method or a surface processing to prepare a gallium nitride semiconductor substrate having residual bending for Experiments A, B, and C.

In the case of the gallium nitride semiconductor substrate for Experiment A, the GaN semiconductor substrate had a thickness of the first GaN layer of about 160 탆 and a thickness of the second GaN layer of about 185 탆, wherein the measured value of the warpage was about Lt; RTI ID = 0.0 > 105 < / RTI >

In the case of the gallium nitride semiconductor substrate for Experiment B, the GaN semiconductor substrate had a thickness of the first GaN layer of about 180 탆 and a thickness of the second GaN layer of about 180 탆, wherein the measured value of the warpage was about Lt; / RTI >

In the case of the gallium nitride semiconductor substrate for Experiment C, the GaN semiconductor substrate had a thickness of about 180 탆 for the first GaN layer and a thickness of about 160 탆 for the second GaN layer, and the measurement value of the warpage was about Lt; / RTI >

Each of the gallium nitride semiconductor substrates was surface-processed according to the bending magnitudes of the gallium nitride semiconductor substrates prepared for the Experiments A, B, and C and the ratio of the thicknesses of the first GaN layer and the second GaN layer. The upper surface of the second GaN layer was surface-processed.

In Experiment A, the ratio of the thickness of the second GaN layer to the thickness of the first GaN layer is about 1.5, and the second GaN layer is thicker than the first GaN layer by about 15% And the amount of change in warpage according to the amount of surface processing was measured. As a result, a graph of FIG. 5 (b) was obtained.

The amount of change in warping with respect to the amount of surface processing was found to be in the range of 1.3 to 1.4 when the surface machining amount of Experiment A was the result of the surface machining amount. When the surface processing amount of the second GaN layer reached about 70 탆, The size of which has dropped to about 10 탆.

Experiment B is a case where the ratio of the thickness of the second GaN layer to the thickness of the first GaN layer is approximately 1 and the thickness of the first GaN layer is similar to that of the second GaN layer, As a result of measuring the amount of change in warpage according to the amount of processing, a graph of FIG. 5 (b) was obtained.

In the graph (B), which is the surface machining amount of Experiment B, the change amount of the warpage with respect to the surface machining amount was in the range of 0.9 to 1. When the surface machining amount of the second GaN layer reached about 85 μm, Lt; RTI ID = 0.0 > 5m. ≪ / RTI >

In Experiment C, the ratio of the thickness of the second GaN layer to the thickness of the first GaN layer is about 0.9, and the second GaN layer is about 10% thinner than the first GaN layer. As a result of measuring the change amount of the warp depending on the amount of surface processing while processing, the graph of (b) to (C) in FIG. 5 was obtained.

In the graph (C), which is the surface machining amount of Experiment C, the amount of change in warping with respect to the amount of surface machining was in the range of 0.8 to 0.9. When the surface machining amount of the second GaN layer reached about 65 μm, Lt; RTI ID = 0.0 > 15 < / RTI >

In the case of a nitride semiconductor substrate having a concave deflection, the amount of change in warpage with respect to the amount of surface processing, that is, (amount of change in warpage / surface machining amount) (The thickness of the second GaN layer / the thickness of the first GaN layer) of the GaN layer, that is, the ratio of the thickness of the GaN layer.

As a result, for a gallium nitride semiconductor substrate having concave warpage, the amount of surface processing can be predicted in advance through the ratio of the warpage, the thickness of the second GaN layer, and the thickness of the first GaN layer. When the surface of the second GaN layer is processed, the warping of the gallium nitride semiconductor substrate can be controlled. However, an error of 5 to 10% may occur due to the difference in the initial surface state and uniformity of the sample, and the error range over a certain level can be corrected by applying a correction constant.

In the above-described present invention, the principles of the warp control according to FIG. 3 and the experimental results of the warp control according to FIG. 5 are explained with respect to the concave warp control of the gallium nitride semiconductor substrate of the first GaN layer and the second GaN layer Taken together, [Expression 2] can be derived.

[Formula 2]

Figure pat00005

Here, W1 is a surface machining amount of the second GaN layer, T1 is a value obtained by dividing the thickness of the second GaN layer by the thickness of the first GaN layer, and B1 is an upper surface of the second GaN layer And is a bending magnitude between the maximum height and the minimum height, and? 1 is a correction constant set at the surface processing of the second GaN layer. At this time,? 1 may be set reflecting the characteristic or the bending characteristic of the nitride semiconductor when it is extended to the nitride semiconductor substrate, and may be a correction constant set for correcting an error according to the surface state or uniformity of the nitride semiconductor substrate .

5, when the ratio of the thickness of the second GaN layer to the thickness of the first GaN layer is about 1.5 in the experiment A in the case of the gallium nitride semiconductor substrate having concave warpage, The change amount is in the range of 1.3 to 1.4. In Experiment B, when the ratio of the thickness of the second GaN layer to the thickness of the first GaN layer is about 1, the change amount of the warping with respect to the surface processing amount is in the range of 0.9 to 1, In the experiment C, when the ratio of the thickness of the second GaN layer to the thickness of the first GaN layer is about 0.9, the amount of change in warping with respect to the amount of surface processing is in the range of 0.8 to 0.9. The correction constant? 1 can be set to 1, since the semiconductor substrate exhibits a numerical tendency in which the variation in warpage with respect to the thickness ratio and the surface processing amount is almost the same. As described above, the correction constant can be set in advance in consideration of various factors such as the characteristics of the nitride semiconductor, the bending characteristics, and the like.

Next, FIG. 6 shows an experimental result of performing warpage control by applying the surface processing principle according to the present invention to a gallium nitride semiconductor substrate in which convex warpage remains. As shown in FIG. 6 (a) The gallium nitride semiconductor substrate of the first GaN layer 110b and the second GaN layer 150b was surface-processed according to the principle of the present invention. As a result, the bending magnitude of the gallium nitride semiconductor substrate shown in FIG. 6 (b) , Respectively.

First, a buffer layer is grown to a thickness of about 10 mu m on a sapphire base substrate, a first GaN layer 110b and a second GaN layer 150b are sequentially grown on the buffer layer, the base substrate is removed, A buffer layer was removed by etching or surface processing to prepare a gallium nitride semiconductor substrate having residual deflection for Experiment D and Experiment E.

In the case of Experiment D and Experiment E, warping in the convex direction is remained. Therefore, the lower surface of the first GaN layer 110b is subjected to the surface treatment by applying the warping control principle according to FIG. 4, A process of planarizing the upper surface of the second GaN layer 150b may be performed. In the case of performing the surface planarization process in the post-treatment process for the nitride semiconductor substrate whose warp is controlled according to the present invention, the balance of the controlled warpage may be destroyed by the present invention. Therefore, before performing the warp control process according to the present invention, It is desirable to perform the planarization process in advance.

In the case of the gallium nitride semiconductor substrate for Experiment D, the GaN semiconductor substrate had a thickness of about 180 탆 for the first GaN layer and a thickness of about 180 탆 for the second GaN layer, wherein the measured value of warpage was a convex bending direction And has a warping size of approximately 95 [mu] m.

 In the case of the gallium nitride semiconductor substrate for Experiment E, the GaN semiconductor substrate had a thickness of the first GaN layer of about 190 탆 and a thickness of the second GaN layer of about 160 탆, wherein the measured value of the warpage was about Lt; RTI ID = 0.0 > 110 < / RTI >

Each of the gallium nitride semiconductor substrates was surface-processed according to the bending magnitudes of the gallium nitride semiconductor substrates prepared for experiments D and E and the thickness ratio of the first GaN layer and the second GaN layer. At this time, Thus, the lower surface of the first GaN layer was surface-processed.

Experiment D shows a case where the thickness ratio of the first GaN layer to the thickness of the second GaN layer is approximately 1 and the thicknesses of the first GaN layer and the second GaN layer are similar. As a result of measuring the amount of change in warpage according to the amount of processing, a graph of FIG. 6 (b) was obtained.

As shown in the graph (A), which is the surface machining amount of Experiment D, the change amount of the deflection with respect to the surface machining amount was in the range of 1.3 to 1.5. When the surface machining amount of the first GaN layer reached about 55 μm, Lt; RTI ID = 0.0 > 15 < / RTI >

In Experiment E, the ratio of the thickness of the first GaN layer to the thickness of the second GaN layer is approximately 1.2, and the first GaN layer is thicker than the second GaN layer by approximately 20% And the amount of change in warpage according to the amount of surface processing was measured. As a result, a graph of FIG. 6 (b) was obtained.

The amount of change in warping with respect to the surface machining amount was found to be in the range of 1.8 to 1.9 when the surface machining amount of the experiment E was examined. When the surface machining amount of the first GaN layer reached about 55 占 퐉, The size of which has dropped to about 10 탆.

In the case of the nitride semiconductor substrate having the warp direction warping, it is preferable that the amount of change in warpage with respect to the amount of surface processing, that is, the amount of warpage / amount of surface processing, (The thickness of the first GaN layer / the thickness of the second GaN layer) of the thickness of the first GaN layer with respect to the thickness of the GaN layer.

As a result, for a gallium nitride semiconductor substrate having a convex bending, the amount of surface processing can be predicted in advance through the ratio of the bending magnitude, the first GaN layer thickness, and the second GaN layer thickness. When the surface of the first GaN layer is processed, warping of the gallium nitride semiconductor substrate can be controlled. However, an error of 5 to 10% may occur due to the difference in the initial surface state and uniformity of the sample, and the error range over a certain level can be corrected by applying a correction constant.

In the above-described present invention, with respect to the convex warpage control of the gallium nitride semiconductor substrate of the first GaN layer and the second GaN layer, the principles of the warp control according to FIG. 4 and the experimental results of the warp control according to FIG. Taken together, [Expression 3] can be derived.

[Formula 3]

Figure pat00006

Herein, W2 is a surface machining amount of the first GaN layer, T2 is a thickness of the first GaN layer divided by a thickness of the second GaN layer, B2 is a bottom surface of the first GaN layer And the angle? 2 is a correction constant set at the time of surface processing of the first GaN layer. At this time, when? 2 is extended to the nitride semiconductor substrate, the? 2 may be set reflecting the characteristic or the bending characteristic of the nitride semiconductor, or may be a correction constant set for correcting an error according to the surface state, uniformity, etc. of the nitride semiconductor substrate .

6, when the ratio of the thickness of the first GaN layer to the thickness of the second GaN layer is about 1 in the experiment D in the case of the convex bending of the gallium nitride semiconductor substrate, Is in the range of 1.3 to 1.5, and when the ratio of the thickness of the first GaN layer to the thickness of the second GaN layer at E is about 1.2, the amount of change in warpage with respect to the amount of surface processing is in the range of 1.8 to 1.9. , The correction constant? 1 can be set to 0.67, which is (1 / 1.5), since the gallium nitride semiconductor substrate in the convexly curved direction exhibits a numerical tendency that the change amount of the warp with respect to the surface processing amount is 1.5 times larger than the thickness ratio. As described above, the correction constant can be set in advance in consideration of various factors such as the characteristics of the nitride semiconductor, the bending characteristics, and the like.

The present invention has been described as an embodiment for controlling the residual warpage of a gallium nitride semiconductor substrate. However, the present invention can be applied to a nitride semiconductor substrate using various nitride semiconductors other than a gallium nitride semiconductor, Of a nitride semiconductor substrate.

The present invention proposes a method of fabricating a nitride semiconductor substrate that controls warpage through surface processing based on the principle of bending control and experimental results of the present invention. FIG. 7 is a view illustrating a method of manufacturing a nitride semiconductor substrate ≪ RTI ID = 0.0 > flowchart < / RTI >

A nitride semiconductor substrate having residual warpage is prepared (S110) through various well-known manufacturing processes of nitride semiconductor substrates. The buffer layer may be removed to form two or more nitride semiconductor layers on the buffer layer, and then the buffer layer may be removed to form the buffer layer. A nitride semiconductor substrate is prepared.

When the nitride semiconductor substrate having residual bending is prepared, the bending direction and the bending magnitude of the nitride semiconductor substrate are grasped (S120), wherein the bending direction is a direction in which the surface of the nitride semiconductor substrate is divided into a concave direction and a convex direction . And the deflection size can be grasped by measuring the size between the maximum height and the minimum height of the surface.

As described above, the upper surface of the uppermost layer of the nitride semiconductor substrate, that is, the uppermost surface of the uppermost layer of the nitride semiconductor substrate can be determined as the processed surface in the case of the concave and deflected directions, The lower surface of the nitride semiconductor substrate, that is, the lower surface of the nitride semiconductor layer, can be determined as the processed surface.

When the machining surface is determined according to the bending direction, the surface machining amount is calculated (S140). The surface machining amount can basically be determined by the above-mentioned [Equation 1], and more specifically, according to the concave bending direction, The surface machining amount can be calculated in accordance with the above-mentioned [Expression 2], and when the lower surface of the nitride semiconductor substrate along the convex bending direction is the machining surface, the surface machining amount can be calculated in accordance with the above [Expression 3] have.

When the machining surface is determined through such a process and the surface machining amount is calculated, the machining surface and the surface machining amount are set as machining conditions (S150).

Then, the surface of the nitride semiconductor substrate is processed (S160) according to the set processing conditions. The machining surface is subjected to a grinding process, followed by a polishing process, The size is controlled (S170). The bending magnitude can be controlled to be less than or equal to 20 占 퐉 through the bending control according to the present invention.

Further, a lapping process may be performed after the grinding process, or a CMP (Chemical Mechanical Polishing) process may be performed after the polishing process, when the surface of the nitride semiconductor substrate is processed. , Such a surface processing method can be selectively added or excluded as needed. In addition to the above-mentioned surface processing methods, various surface processing methods can be applied.

In the method of manufacturing a nitride semiconductor substrate in which the bending is controlled through the surface processing according to the present invention, all processes or selective processes from the bending direction and bending magnitude determination process (S120) to the bending control process (S170) are performed through the bending control device FIG. 8 shows a configuration diagram of an embodiment of a warpage control apparatus for performing a method of manufacturing a nitride semiconductor substrate that controls warpage through surface processing according to the present invention.

The warpage controlling apparatus 300 for performing the method of manufacturing a nitride semiconductor substrate for controlling warpage through surface processing according to the present invention includes a warpage measuring unit 310, a processing amount calculating unit 330, and a surface processing unit 350 And each of the configurations may be included in one device and each configuration may be configured in a separate device.

The bending measuring unit 310 measures the bending direction and the bending magnitude of the nitride semiconductor substrate having residual bending. For example, the bending measuring unit 310 includes a light emitting unit and a light receiving unit. The bending measuring unit 310 measures the surface shape of the nitride semiconductor substrate through light irradiation, It is also possible to grasp the warpage and also to grasp the highest height and the lowest height on the surface of the nitride semiconductor substrate through light irradiation and calculate the height difference to determine the warpage size.

The machining amount calculating unit 330 calculates the surface machining amount on the basis of the bending direction and the bending magnitude measured by the bending measuring unit 310. The surface machining amount can be calculated by applying the above-mentioned [Expression 1] The surface machining amount can be calculated by adding the above-mentioned [Equation 2] and the above-mentioned [Equation 3]. At this time, nitride semiconductor information, surface state information, correction constant information, and the like may be additionally input.

The machining amount calculating unit 330 also generates machining condition information by setting the machining conditions including the bending direction and the calculated surface machining amount.

The machining condition information generated by the machining amount calculating unit 330 is transmitted to the surface machining unit 350 and the surface machining unit 350 processes the surface of the nitride semiconductor substrate according to the machining conditions.

The surface machining unit 350 may optionally include a grinding means, a lapping means, a polishing means, a post-CMP (Chemical Mechanical Polishing) means, And the surface processing of the nitride semiconductor substrate is performed by using the respective surface processing means.

A method of fabricating a nitride semiconductor substrate for controlling warpage through surface processing according to the present invention will now be described in more detail with reference to process embodiments.

First, with reference to a process of controlling warpage of a gallium nitride semiconductor substrate having a concave deflection, FIG. 9 shows a process for a first embodiment of a method of manufacturing a nitride semiconductor substrate for controlling warpage through surface processing according to the present invention.

A buffer layer 50 is grown on a growth substrate 10 which is a heterogeneous substrate and a first GaN layer 110 and a second GaN layer 150 are successively grown thereon. At this time, the first GaN layer 110 is grown as a semiconductor layer having a high defect density and the second GaN layer 150 is grown as a semiconductor layer having a low defect density.

When the substrate 10 for growth is removed, the concave deflection remains due to the stress due to the stress. After removing the buffer layer 50 in the lowermost layer, the machined surface is determined by grasping the concave deflection direction by measuring the deflection direction . The thickness Dt1 of the first GaN layer 110a and the thickness Dt2 of the second GaN layer 150a are measured and the bending magnitude B1 is measured to calculate the surface machining amount.

The processing conditions for the surface processing of the gallium nitride semiconductor substrate are set based on the machining surface and the surface machining amount and the upper surface of the second GaN layer 150a which is the machining surface is processed by the surface machining amount in accordance with the set machining conditions . At this time, a grinding process, a lapping process, a polishing process, and a CMP (Chemical Mechanical Polishing) process are optionally performed.

As the upper surface of the second GaN layer 150a is surface-processed, the tensile stress of the second GaN layer 150a gradually decreases from Ft1 to Ft2 according to the degree of surface processing, and the tensile stress of the second GaN layer 150a It is possible to obtain a gallium nitride semiconductor substrate composed of a flat second GaN layer 250a and a first GaN layer 210a when reduced to a size similar to the compressive stress of the first GaN layer 110a.

As described above, according to the present invention, it is possible to manufacture a flat, high-quality nitride semiconductor substrate by controlling the warpage of the nitride semiconductor substrate in which the warping in the concave direction remains.

Next, with reference to a process for controlling warping of a gallium nitride semiconductor substrate having warp direction warpage, FIG. 10 shows a process diagram for a second embodiment of a method for manufacturing a nitride semiconductor substrate for controlling warp through surface processing according to the present invention.

10, the buffer layer 50, the first GaN layer 110, and the second GaN layer 150 are sequentially formed on the growth substrate 10 in the same manner as in the first embodiment of FIG. Growth.

When the substrate for growth 10 is removed, warping in the convex direction is left due to stress due to stress, and in the case of warping in the convex direction, the surface of the upper surface of the gallium nitride semiconductor substrate is first planarized.

The convex bending direction is determined by measuring the warp direction of the gallium nitride semiconductor substrate having residual warpage to determine the machined surface and the thickness Dc1 of the first GaN layer 110b and the thickness Dc2 of the second GaN layer 150b are measured Further, the bending magnitude B2 is measured, and the surface machining amount corresponding thereto is calculated.

Processing conditions are set based on the machining surface and the surface machining amount, and the lower surface of the first GaN layer 150b, which is the machining surface, is machined by the surface machining amount in accordance with the set machining conditions. At this time, a grinding process, a lapping process, a polishing process, a CMP (Chemical Mechanical Polishing) process, and the like can be selectively performed as necessary in the same manner as the first embodiment of FIG.

As the lower surface of the first GaN layer 110b is surface-processed, the compressive stress of the first GaN layer 110b gradually decreases from Fc1 to Fc2 according to the degree of surface processing, and the compressive stress of the first GaN layer 110a It is possible to obtain a gallium nitride semiconductor substrate composed of the first GaN layer 210b and the second GaN layer 250b which are flat and reduced in size to a size similar to the tensile stress of the second GaN layer 150b.

As described above, according to the present invention, it is possible to manufacture a flat, high-quality nitride semiconductor substrate by controlling the warping of the nitride semiconductor substrate in which the warping direction remains.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments of the present invention are not intended to limit the scope of the present invention but to limit the scope of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents thereof should be construed as being included in the scope of the present invention.

10: Growth base substrate,
50: buffer layer,
110, 110a, 110b, 210a, 210b: a first GaN layer,
150, 150a, 150b, 250a, 250b: a second GaN layer,
300: warpage control device of nitride semiconductor substrate,
310: warp measuring part,
330: processing amount calculating section,
350: Surface machining part.

Claims (8)

A method of manufacturing a nitride semiconductor substrate,
A semiconductor substrate preparation step of preparing a nitride semiconductor substrate in which at least two or more nitride semiconductor layers which are lowered in defect density toward the upper layer are successively stacked to generate a bow;
Determining a bending direction and a bending magnitude of the nitride semiconductor substrate to determine a machining surface of the nitride semiconductor substrate along the bending direction and calculating a surface machining amount based on the bending direction and the bending magnitude, A machining condition setting step of setting a machining condition according to the surface machining amount; And
And a surface processing step of processing the processed surface of the nitride semiconductor substrate according to the processing conditions to control the warping of the nitride semiconductor substrate. The method according to claim 1,
The machining condition setting step includes:
Characterized in that a warp direction of either the concave or the convex is determined based on the upper surface of the nitride semiconductor substrate and the magnitude between the highest height and the lowest height on the surface of the nitride semiconductor substrate is measured, A method of manufacturing a semiconductor substrate. The method according to claim 1,
The machining condition setting step includes:
The upper surface of the nitride semiconductor substrate is determined as a machining surface when the bending direction is concave and the lower surface of the nitride semiconductor substrate is determined as a machining surface when the bending direction is convex,
The surface machining amount is calculated by the following expression (1)
[Formula 1]
Figure pat00007

Wherein W is a surface machining amount, T is a thickness ratio between an uppermost layer and a lowermost layer in the nitride semiconductor layer, B is a bending magnitude, and? Is a predetermined correction constant. The method according to claim 1,
The semiconductor substrate preparation step may include:
Forming a buffer layer on the base substrate and sequentially stacking two or more nitride semiconductor layers on the buffer layer;
Removing the base substrate; And
And removing the buffer layer to prepare a nitride semiconductor substrate composed of two or more nitride semiconductor layers. The method according to claim 1,
The semiconductor substrate preparation step may include:
A nitride semiconductor substrate having a second GaN layer stacked on the first GaN layer is prepared,
The machining condition setting step includes:
The upper surface of the second GaN layer is determined as a machined surface when the warping direction is concave, and the surface machining amount is calculated by the following expression (2)
[Formula 2]
Figure pat00008

Here, W1 is a surface processing amount of the second GaN layer, T1 is a value obtained by dividing the thickness of the second GaN layer by the thickness of the first GaN layer, B1 is a maximum height on the upper surface of the second GaN layer And a minimum height of the second GaN layer, and the alpha 1 is a correction constant set at the time of surface processing of the second GaN layer. The method according to claim 1,
The semiconductor substrate preparation step may include:
A nitride semiconductor substrate having a second GaN layer stacked on the first GaN layer is prepared,
The machining condition setting step includes:
The lower surface of the first GaN layer is determined as a machined surface when the warping direction is convex, and the surface machining amount is calculated by the following expression (3)
[Formula 3]
Figure pat00009

Wherein W2 is a surface machining amount of the first GaN layer, T2 is a thickness of the first GaN layer divided by a thickness of the second GaN layer, B2 is a height of a bottom surface of the first GaN layer And a minimum height of the first GaN layer, and? 2 is a correction constant set at the time of surface processing of the first GaN layer. The method according to claim 1,
The surface processing step may include:
Wherein the nitride semiconductor substrate is controlled to have a warpage of 20 μm or less by sequentially performing a grinding process and a polishing process on the machined surface in accordance with the machining conditions, . 8. The method of claim 7,
The surface processing step may include:
Further comprising performing a lapping process after a grinding process, and further performing a CMP (Chemical Mechanical Polishing) process after a polishing process.
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KR101967716B1 (en) * 2018-02-05 2019-04-10 주식회사 루미스탈 MANUFACTURING METHOD FOR GaN WAFER

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KR100680670B1 (en) 2002-06-28 2007-02-09 히다치 덴센 가부시끼가이샤 POROUS SUBSTRATE AND ITS MANUFACTURING METHOD, AND GaN SEMICONDUCTOR MULTILAYER SUBSTRATE AND ITS MANUFACTURING METHOD

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100680670B1 (en) 2002-06-28 2007-02-09 히다치 덴센 가부시끼가이샤 POROUS SUBSTRATE AND ITS MANUFACTURING METHOD, AND GaN SEMICONDUCTOR MULTILAYER SUBSTRATE AND ITS MANUFACTURING METHOD

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101967716B1 (en) * 2018-02-05 2019-04-10 주식회사 루미스탈 MANUFACTURING METHOD FOR GaN WAFER

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