TWI665333B - Method of manufacturing substrate for epitaxy - Google Patents

Abstract

A method for manufacturing a substrate for epitaxy includes: providing a buffer layer on a substrate. The buffer layer is formed by using an atomic layer deposition process to form a plurality of stacked nitride layers. The buffer layer may also be composed of at least one first buffer layer and at least one second buffer layer. The first buffer layer is formed by using an atomic layer deposition process to form a plurality of stacked first nitride layers. The second buffer layer is formed by using an atomic layer deposition process to form a plurality of stacked second nitride layers. In the step of fabricating the buffer layer, after forming each nitride layer, the first nitride layer, or the second nitride layer, ion bombardment is continued. Thereby, the substrate and the buffer layer form a substrate for epitaxy, and the degree of crystallization of the buffer layer is effectively improved.

Description

Manufacturing method of substrate for epitaxy

The invention relates to a substrate for epitaxy; in particular, it relates to a method for manufacturing a substrate for epitaxy.

Existing semiconductor devices, such as semiconductor light-emitting devices, high-electron-mobility transistor (HEMT), laser diodes, etc., mostly grow a buffer layer on a substrate, and then An epitaxial layer is grown on the buffer layer, and then a device structure is fabricated on the epitaxial layer. The purpose of the buffer layer is to reduce the lattice mismatch, reduce the defect density, or reduce the difference in thermal expansion coefficient between the substrate and the epitaxial layer, so as to improve the quality of the epitaxial layer and thus the efficiency of the device.

Existing technologies for making buffer layers mostly use a metal-organic chemical vapor deposition (MOCVD) process to make a buffer layer (such as an aluminum nitride or gallium nitride buffer layer) on a substrate, usually an organic metal The process temperature of the chemical vapor deposition process needs to be at a high temperature to allow the buffer layer to crystallize to improve the quality of the buffer layer. Because the process temperature is high, the power consumed by the process machine is relatively high, and the thermal stability of the substrate is also high.

In view of this, an object of the present invention is to provide a method for manufacturing a substrate for epitaxy, which can produce a buffer layer having a good degree of crystallinity at a lower process temperature.

In order to achieve the above object, the present invention provides a method for manufacturing a substrate for epitaxy, the substrate includes a substrate and a buffer layer; the manufacturing method includes the following steps: A, providing the substrate; B, on the substrate The buffer layer is disposed on one surface, and the steps of setting the buffer layer include: B-1, forming a nitride layer using an atomic layer deposition process; B-2, ion bombarding the nitride layer; and B-3, heavy Steps B-1 and B-2 are repeated several times, so that the plurality of stacked nitride layers constitute the buffer layer having a predetermined thickness.

The invention further provides a method for manufacturing a substrate for epitaxy, the substrate comprising a substrate and a buffer layer; the manufacturing method includes the following steps: A. providing the substrate; B. setting the buffer on a surface of the substrate Layer, the buffer layer includes at least one first buffer layer and at least one second buffer layer that are stacked; wherein the step of forming the first buffer layer includes: B-1, forming a first buffer layer using an atomic layer deposition process; A nitride layer; B-2, performing ion bombardment on the first nitride layer; and B-3, repeating steps B-1 and B-2 a plurality of times so that a plurality of stacked first nitride layers are formed The first buffer layer having a first predetermined thickness; wherein the step of forming the second buffer layer includes forming a plurality of stacked second nitride layers using an atomic layer deposition process until the second nitrides The thickness of the layer reaches a second predetermined thickness to constitute the second buffer layer.

The effect of the present invention is that each layer of the nitride layer or the first nitride layer in the buffer layer is produced by an atomic layer deposition process with a lower process temperature requirement, and each layer of the nitride layer or the first nitride layer is formed by a plasma. The ion bombardment can effectively improve the crystallization degree of the buffer layer, effectively improve the crystallization quality of the epitaxial layer formed above the buffer layer, and make the epitaxial layer have a better crystallization degree.

〔this invention〕

1, 1’‧‧‧ substrate

10, 10’‧‧‧ substrate

102‧‧‧ surface

12, 12’‧‧‧ buffer layer

2‧‧‧ substrate

20‧‧‧ substrate

202‧‧‧ surface

22‧‧‧ buffer layer

222‧‧‧First buffer layer

224‧‧‧Second buffer layer

3‧‧‧ substrate

30‧‧‧ substrate

302‧‧‧ surface

32‧‧‧ buffer layer

322‧‧‧First buffer layer

324‧‧‧Second buffer layer

FIG. 1 is a schematic diagram of a substrate manufactured by a manufacturing method according to a first preferred embodiment of the present invention.

FIG. 2 is a flowchart of a manufacturing method according to a first preferred embodiment of the present invention.

FIG. 3 shows the results of X-ray diffraction (θ-2θ mode) detection of the substrate of the first preferred implementation and other control substrates.

FIG. 4 shows the results of the first preferred substrates with different ion bombardment time and the control group substrates under X-ray diffraction (θ-2θ mode).

FIG. 5 is a result of a first preferred implementation of a manufacturing method using a silicon substrate and a control substrate in X-ray diffraction (θ-2θ mode) detection.

FIG. 6 is a flowchart of a manufacturing method of a second preferred embodiment of the present invention.

FIG. 7 is a schematic diagram of a substrate manufactured by a manufacturing method of a second preferred embodiment of the present invention.

FIG. 8 shows the results of X-ray diffraction (θ-2θ mode) detection of the substrate and the control substrate of the second preferred embodiment.

FIG. 9 is a result of detecting the X-ray diffraction rocking curve (omega mode) of the substrate of sample 1 in FIG. 8.

FIG. 10 is a result of detecting the X-ray diffraction (θ-2θ mode) of the substrate in the second preferred embodiment under different ion bombardment time and different plasma power.

FIG. 11 is a result of detecting the X-ray diffraction (θ-2θ mode) of the substrate in the second preferred embodiment at different delay times.

FIG. 12 is a graph showing the relationship between the X-ray diffraction intensity and the delay time of samples 1 to 4 in FIG. 11.

FIG. 13 is an image of a cross section near the interface between the buffer layer 12 and the substrate of the present embodiment observed with a high-resolution transmission electron microscope.

14 is a schematic diagram of a substrate manufactured by a manufacturing method according to a third preferred embodiment of the present invention.

15 is a flowchart of a manufacturing method according to a third preferred embodiment of the present invention.

FIG. 16 shows the results of detection on the X-ray diffraction rocking curve (omega mode) after growing GaN epitaxial layers on the substrates of the first and third preferred embodiments, respectively.

FIG. 17 is a schematic diagram of a substrate according to a fourth preferred embodiment of the present invention.

FIG. 18 is a result of detecting the X-ray diffraction rocking curve (omega mode) of the substrate and its semi-finished product in the fourth preferred embodiment.

In order to explain the present invention more clearly, preferred embodiments are described in detail below with reference to the drawings. Please refer to FIG. 1, a substrate 1 manufactured by using a method for manufacturing a substrate for epitaxy according to a first preferred embodiment of the present invention. The substrate 1 includes a substrate 10 and a buffer layer 12. The substrate 10 It is a sapphire substrate, but it is not limited to this. It can also be a silicon, gallium nitride, silicon carbide, or gallium arsenide substrate. The buffer layer 12 is disposed on a surface 102 of the substrate 10. The surface 102 of the buffer layer 12 is provided with an epitaxial layer (not shown) such as a gallium nitride epitaxial layer.

The manufacturing method of this embodiment includes the following steps shown in FIG. 2: providing the substrate 10, and disposing the buffer layer 12 having a predetermined thickness on the surface 102 of the substrate 10. The steps of disposing the buffer layer 12 include: using An atomic layer deposition (ALD) process (Atomic Layer Deposition, ALD) grows a nitride layer on the surface 102 of the substrate 10 with an aluminum nitride (AlN) layer (ie, an aluminum nitride atomic layer) as an example. The process parameters of the atomic layer deposition process are a process temperature of 500 ° C; trimethylaluminum (TMA): 0.06 seconds; NH ₃ plasma: 40 seconds; the thickness of the aluminum nitride layer is between 0.1 and 3 Å.

Then, the aluminum nitride layer is ion bombarded with a plasma. In this embodiment, when the process temperature is 500 ° C., the aluminum nitride layer is ion bombarded with an argon (Ar) plasma, and the plasma power is 300W. So that the aluminum nitride layer is crystallized, and the ion bombardment time is more than 10 seconds. Considering the trade-off between the overall process time and the crystallinity of the aluminum nitride layer, the preferred ion bombardment time is between 20 seconds and 40 seconds. The effect of different ion bombardment time on the degree of crystallization will be described later. In practice, other gases can also be used to generate plasma, for example, N ₂ , H ₂ , He, Ne, NH ₃ , N ₂ / H ₂ , N ₂ O, CF ₄ and other gases.

Then, on the aluminum nitride layer after ion bombardment, a new aluminum nitride layer is grown by using the atomic layer deposition process, and the newly formed aluminum nitride layer is subjected to ion bombardment with argon plasma in the same manner as above; This step is repeated several times to form a laminated aluminum nitride layer on the substrate 10 until the total thickness of the aluminum nitride layers on the substrate 10 reaches the predetermined thickness and then stops. The predetermined thickness ranges from 5 nm to 200 nm. In this embodiment, the predetermined thickness ranges from 20 nm to 50 nm.

Please refer to FIG. 3, which shows the results of X-ray diffraction (θ-2θ mode) for different substrates. The curve of sample one is substrate 1 of this example, and the argon ion bombardment time is 10 seconds. The plasma power is 300W; the curve of sample two is the control group, and the buffer layer is also made by the atomic layer deposition process. The difference is that only argon is passed for 10 seconds without generating plasma. It is obvious from FIG. 3 that in the manufacturing process of the substrate 1 of this embodiment, the use of argon ion bombardment each time the aluminum nitride layer is formed has the effect of significantly increasing the crystallinity of the buffer layer 12.

Please refer to FIG. 4, which is the result of X-ray diffraction (θ-2θ mode) detection of the substrate 1 produced by the manufacturing method of this embodiment. The curve of sample one is 40 seconds per argon ion bombardment time. The plasma power is 300W; the curve of sample two is 20 seconds for each argon ion bombardment time, and the plasma power is 300W; the curve of sample three is 10 seconds for each argon ion bombardment time, and the plasma power is 300W; sample four The curve is the control group, and the buffer layer is also made by the atomic layer deposition process, the difference is that no argon ion bombardment step is performed. It is apparent from FIG. 4 that the longer the argon ion bombardment time, the better the crystallinity of the buffer layer 12 is. From the ion bombardment time between 20 seconds and 40 seconds, it can be known that the degree of crystallization is not much different after more than 20 seconds. Therefore, considering the overall process time and the crystallinity of the buffer layer 12, the ion bombardment is preferred. The time can be set between 20 seconds and 40 seconds.

In practice, a silicon substrate can also be used as the substrate in the manufacturing method of this embodiment, and its crystal orientation is 111. Please refer to FIG. 5 for the results of X-ray diffraction (θ-2θ mode) detection of the substrate using the silicon substrate. Among them, the curve of sample one is 40 seconds for each argon ion bombardment time and the plasma power is 300W; the curve of sample two is 20 seconds for each argon ion bombardment time and the plasma power is 300W; the curve for sample three is Each argon ion bombardment time is 10 seconds, and the plasma power is 300W. The curve of sample four is the control group, and the buffer layer is also made by the atomic layer deposition process. The difference is that the argon ion bombardment step is not performed. It is obvious from FIG. 5 that the longer the argon ion bombardment time of the buffer layer fabricated on the silicon substrate, the better the crystallinity of the buffer layer is. From the ion bombardment time between 20 seconds and 40 seconds, it can be known that the degree of crystallization has not changed much after 20 seconds. Therefore, considering the trade-off between the overall process time and the crystallinity of the buffer layer, the preferred ion bombardment time is Can be set between 20 and 40 seconds.

In the foregoing first embodiment, the nitride layer constituting the buffer layer 12 is based on an aluminum nitride (AlN) layer. In practice, GaN, Al _x Ga _1-x N, and In _x Ga _1-x N may also be used. , InN, Al _x In _y Ga _1-xy N and other nitrides.

FIG. 6 is a flowchart of a method for manufacturing a substrate for epitaxy according to a second preferred embodiment of the present invention, for manufacturing the substrate 1 ′ shown in FIG. 7. The substrate 10 is a sapphire substrate, but is not limited thereto, and may be a silicon, gallium nitride, silicon carbide, or gallium arsenide substrate. The method has substantially the same steps as the first embodiment, wherein the process parameters of the atomic layer deposition process are a process temperature of 300 ° C; trimethylaluminum: 0.06 seconds; N ₂ / H ₂ plasma: 40 seconds; the nitriding The thickness of the aluminum layer is between 0.1 and 3 Å. The difference from the first embodiment is that, in this embodiment, after each ion bombardment of the aluminum nitride layer with an argon plasma, the plasma generation is stopped first, and within a delay time after the plasma generation is stopped, The atomic layer deposition process continued to grow a new aluminum nitride layer, that is, the time difference between stopping the argon plasma and re-injecting trimethyl aluminum was the delay time. Thereby, the aluminum nitride layer laminated on the substrate 10 'constitutes the buffer layer 12'.

Please refer to FIG. 8, which shows the results of X-ray diffraction (θ-2θ mode) of different substrates. The curve of sample 1 is the substrate 1 ′ of this embodiment, and the argon ion bombardment time is 20 Second, the plasma power is 300W; the curve of sample two is the control group, and the buffer layer is also made by the atomic layer deposition process. The difference is that each layer of aluminum nitride is not bombarded with argon ions, but the buffer layer is formed. Then, the buffer layer was subjected to argon ion bombardment. Among them, the plasma power was 300W and the bombardment time was 4000 seconds. The curve of sample three is another control group. The difference is that argon gas is not separately applied to each aluminum nitride layer. Ion bombardment was also performed without argon ion bombardment after the buffer layer was formed. It is obvious from FIG. 8 that in the manufacturing process of the substrate 1 'of this embodiment, the use of argon ion bombardment each time the aluminum nitride layer is formed has the effect of significantly increasing the crystallinity of the buffer layer 12'.

Please refer to FIG. 9, which shows the results of the detection of the substrate 1 ′ of the sample 1 of FIG. 8 on the X-ray diffraction rocking curve (omega mode); it can be seen from FIG. 9 that the sample 1 is observed in the omega detection mode. To the peak, and sample two and sample three in Figure 8 are omega No peak was observed in the detection mode, so it is not listed in FIG. 9. From this, it can be proved that in the manufacturing method of this embodiment, the buffer layer 12 'can have a high degree of crystallinity by argon ion bombardment.

FIG. 10 is a result of the X-ray diffraction (θ-2θ mode) detection of the substrate 1 'of this embodiment under different argon ion bombardment times and different plasma powers. Among them, the electricity on the left (a) will be 100W, and the argon ion bombardment time will be 10 seconds, 20 seconds, and 40 seconds; the electricity on the right (b) will be 300W and the argon ion bombardment time will be 10 respectively. Seconds, 20 seconds, 40 seconds. It can be seen from FIG. 10 that the longer the argon ion bombardment time for each aluminum nitride layer, the higher the crystallinity of the buffer layer 12 '; and the higher the plasma power of the argon ion bombardment, the more the crystallinity of the buffer layer 12' high. When the plasma power is 300W, the ion bombardment time is 20 seconds and 40 seconds, and the degree of crystallization of the buffer layer 12 'is quite close. Therefore, it can be concluded that the better plasma power is 300W and the ion bombardment time is more than 20 seconds. . Figure 8 and Figure 10 are different because of different measuring machines, so the X-ray diffraction intensity is slightly different.

FIG. 11 shows the continuity of the argon plasma after stopping the argon plasma after the argon ion bombardment at a plasma power of 300 W for 20 seconds each time, and before the next growth of a new aluminum nitride layer by the atomic layer deposition process. Results of detection of X-ray diffraction (θ-2θ mode) of substrate 1 'with different delay times. Among them, sample one has a delay time of 0 seconds, that is, a new aluminum nitride layer is grown immediately after stopping the plasma; sample two has a delay time of 5 seconds, that is, waits for 5 seconds after stopping the plasma to continue to grow new nitrogen. Aluminium layer; Sample 3 is a delay time of 10 seconds; Sample 4 is a delay time of 20 seconds; Sample 5 is not argon ion bombardment of each aluminum nitride layer separately, nor is argon applied to the buffer layer after forming the buffer layer Gas ion bombardment. FIG. 12 is a graph showing the relationship between the X-ray diffraction intensity and the delay time of samples 1 to 4 in FIG. 11. As can be clearly seen from Figs. 11 and 12, the shorter the delay time before stopping the plasma until the next growth of the new aluminum nitride layer, the higher the degree of crystallization of the buffer layer 12 '. Preferably, the delay time is within 5 seconds.

FIG. 13 is an image of a cross section near the interface between the buffer layer 12 ′ and the substrate 10 ′ according to the present embodiment observed with a high-resolution transmission electron microscope. In FIG. 13, (b) and (c) are fast Fourier transform (FFT) diffraction patterns of the buffer layer 12 ′ and the substrate 10 ′, respectively. It can be observed from FIG. 13 (a) that the buffer layer 12 'exhibits an ordered atomic arrangement. From its fast Fourier transform diffraction pattern, it can be seen that the buffer layer 12' has a high-quality single crystal structure, and its crystal orientation is [0001 ]. In Figure 13, after comparing (b) and (c), the epitaxial relationship of the buffer layer 12 'with respect to the substrate 10' can be obtained: [0001] _{buffer layer} // [0001] _substrate , and [1010] _{buffer layer} // [1120] _substrate .

Please refer to FIG. 14, a substrate 2 manufactured by using a method for manufacturing a substrate for epitaxy according to a third preferred embodiment of the present invention. The substrate 2 includes a substrate 20 and a buffer layer 22. The substrate 20 It is a sapphire substrate, but it is not limited to this. It can also be a silicon, gallium nitride, silicon carbide, or gallium arsenide substrate. The buffer layer 22 includes a plurality of first buffer layers 222 and a plurality of second buffer layers stacked alternately. Buffer layer 224. In this embodiment, the first buffer layer 222 is located on the surface 202 of the substrate 20, and the second buffer layer 224 located at the top is provided with an epitaxial layer (not shown) such as gallium nitride epitaxial. Floor.

The manufacturing method of this embodiment includes the following steps shown in FIG. 15: providing the substrate 20 and fabricating the buffer layer 22 on the surface 202 of the substrate 20, wherein the steps of setting each of the first buffer layers 222 include: using An atomic layer deposition process grows a first nitride layer on the surface 202 of the substrate 20 with an aluminum nitride layer (ie, an aluminum nitride atomic layer) as an example. The process parameters of the atomic layer deposition process are: process temperature 500 ° C, TMA, 0.06 seconds; NH ₃ , 40 seconds. The thickness of the aluminum nitride layer is between 0.1 and 3 Å.

Then, the aluminum nitride layer is ion bombarded with a plasma. In this embodiment, the aluminum nitride layer is ion bombarded with an argon plasma at a process temperature of 500 ° C. The plasma power is 300 W so that The aluminum nitride layer is crystallized, and the ion bombardment time is 10 seconds or more. Considering the trade-off between the overall process time and the crystallinity of the aluminum nitride layer, the preferred ion bombardment time is between 20 seconds and 40 seconds, and the most preferred is 40 seconds. The plasma used may also be a plasma formed of one of N ₂ , H ₂ , He, Ne, NH ₃ , N ₂ / H ₂ , N ₂ O, and CF ₄ .

Then, on the aluminum nitride layer after ion bombardment, a new aluminum nitride layer is grown by using the atomic layer deposition process, and the newly formed aluminum nitride layer is subjected to ion bombardment with argon plasma in the same manner as above; This step is repeated several times to form a laminated aluminum nitride layer on the substrate 20 until the total thickness of the aluminum nitride layers of the substrate 20 reaches a first predetermined thickness and then stops. The first predetermined thickness is between 1 nm and 50 nm, and is 3.9 nm in this embodiment. Accordingly, the aluminum nitride layers constitute the first buffer layer.

Next, a second buffer layer 224 is fabricated on the first buffer layer 222. The steps include forming a plurality of stacked gallium nitride (GaN) layers (ie, gallium nitride atomic layers) using an atomic layer deposition process. The second nitride layer as an example, until the thickness of the gallium nitride layers reaches a second predetermined thickness, and the second predetermined thickness is between 1 nm and 50 nm to form a second buffer layer. The process parameters of each gallium nitride layer are the process temperature of 500 ° C; Triethylagallium (TEGa), 0.1 second; and the mixed gas plasma of NH ₃ and hydrogen, 20 seconds. The thickness of each gallium nitride layer is between 0.1 and 3 Å. In this embodiment, the step of ion bombarding the newly formed gallium nitride layer with an argon plasma is not applied.

After that, another first buffer layer 222 and another second buffer layer 224 that are stacked are repeatedly made several times. Thereby, a buffer layer 22 is formed on the substrate 20 by stacking the plurality of first buffer layers 222 and the plurality of second buffer layers 224 alternately. In this embodiment, the buffer layer is formed by stacking three pairs of the first buffer layer 222 and the second buffer layer 224. In this way, the production of the substrate 2 of this embodiment is completed. Since each gallium nitride layer of the second buffer layer 224 has not been bombarded by ions, its crystallinity is lower than that of the first buffer layer 222. The secondary buffer layer 224 can further serve as an absorption layer for defects and stresses, thereby reducing the chance of defects penetrating into the epitaxial layer after the epitaxial layer is additionally grown on the buffer layer 22.

In practice, as in the second embodiment, after the ion bombardment of each aluminum nitride layer, within a delay time after stopping the plasma, the atomic layer deposition process is continued to grow a new aluminum nitride layer. The better, the delay time is preferably within 5 seconds.

In addition, during the fabrication of each second buffer layer 224, after each gallium nitride layer is formed, the formed gallium nitride layer is subjected to ion bombardment with a plasma to make the second buffer The gallium nitride layers in the layer 224 are crystallized to obtain a buffer layer 222 with a higher degree of crystallinity. The plasma used is a plasma formed by one of Ar, N ₂ , H ₂ , He, Ne, NH ₃ , N ₂ / H ₂ , N ₂ O, and CF ₄ . In practice, as in the second embodiment, after the ion bombardment of each gallium nitride layer, within a delay time after stopping the plasma, the atomic layer deposition process is continued to grow a new gallium nitride layer. The better, the delay time is preferably within 5 seconds.

Please refer to FIG. 16, the substrate 2 produced by the manufacturing method of this embodiment and the substrate 1 of the first embodiment are grown on the gallium nitride epitaxial layer, and then the X-ray diffraction rocking curve (omega mode) ) Test results. The GaN epitaxial layer is grown by MOCVD technology. The process temperature is 1180 ° C. The substrates 1 and 2 are annealed in a MOCVD chamber in an ammonia atmosphere for five minutes, and then 1.5 μm of nitrogen is grown on the substrates 1 and 2. The gallium epitaxial layer, in which the curve of sample one is that the second predetermined thickness of each of the second buffer layers 224 of the substrate 2 is 3.5 nm, and each time the aluminum nitride layer is bombarded with argon ions for 40 seconds, The plasma power is 300W; the curve of sample two is that the second predetermined thickness of the second buffer layer 224 of the substrate 2 is 1.8nm, and the aluminum nitride layer is bombarded with argon ion for 40 seconds each time. The power is 300W; the sample 3 is the substrate 1 of the first embodiment, and the argon ion bombardment time of the aluminum nitride layer is 40 seconds, and the plasma power is 300W. It is obvious from FIG. 16 that the substrate 2 of this embodiment can more effectively improve the crystalline quality of the epitaxial layer above the buffer layer compared to the substrate 1 of the first embodiment, so that the epitaxial layer has a better quality. Degree of crystallinity.

In practice, the positions of each of the first buffer layers 222 and each of the second buffer layers 224 can also be reversed up and down. The manufacturing methods are substantially the same, except that a second buffer layer is provided before the surface of the substrate 20. 224, and then a first buffer layer 222 is provided and ion bombardment is performed. Since each gallium nitride layer of the second buffer layer 224 has not been bombarded by ions, its crystallinity is lower than that of the first buffer layer 222. Thus, the second buffer layer 224 can be further generated as a result of lattice mismatch. The defect and stress absorbing layer can reduce the chance of defects penetrating into the epitaxial layer after the epitaxial layer is grown on the buffer layer 22. In addition, the number of the first buffer layers 222 and the number of the second buffer layers 224 may be at least one layer respectively.

In the third embodiment described above, the first nitride layer constituting the first buffer layer 222 is an aluminum nitride (AlN) layer as an example. In practice, GaN, Al _x Ga _1-x N, In _x may also be used. Ga _1-x N, InN, Al _x In _y Ga _1-xy N and other nitrides. The second nitride layer constituting the second buffer layer 224 is based on a gallium nitride (GaN) layer. In practice, AlN, Al _x Ga _1-x N, In _x Ga _1-x N, InN can also be used. , Al _x In _y Ga _1-xy N and other nitrides. The materials of the first nitride layer and the second nitride layer may be different materials or the same material.

FIG. 17 shows a substrate 3 according to a fourth preferred embodiment of the present invention, which has a structure substantially the same as that of the third embodiment, and includes a substrate 30 and a buffer layer 32. The substrate 10 is a sapphire substrate, but not based on This is limited, and may also be a silicon, gallium nitride, silicon carbide, or gallium arsenide substrate; the difference is that the buffer layer 32 includes at least one first buffer layer 322 and at least one second buffer layer 324 that are stacked, The materials of the first buffer layer 322 and the second buffer layer 324 are the same, and the thicknesses of the two are taken as an example of 18 nm. The manufacturing method of the substrate 3 is substantially the same as that of the third embodiment. The difference is that the second buffer layer 324 is provided by an atomic layer deposition process before the surface 302 of the substrate 30. Each second nitride layer of the layer 324 uses aluminum nitride as an example, and each second nitride layer is not ion bombarded by a plasma. Then, the first buffer layer 322 is disposed on the second buffer layer 324 by an atomic layer deposition process. Each first nitride layer of the first buffer layer 322 also uses aluminum nitride as an example. After each first nitride layer is formed, the first nitride layer is ion bombarded with a plasma and stopped. A new first nitride layer continues to grow within the delay time after the plasma, wherein the delay time is within 5 seconds.

In practice, if the number of the first buffer layer 322 and the number of the second buffer layer 324 are plural layers, the buffer layer is the same structure as the third embodiment is staggered, the difference is only the second buffer The layer 324 is in contact with the surface 302 of the substrate 30.

Please refer to FIG. 18, which shows the results of X-ray diffraction rocking curve (omega mode) of different substrates. Among them, sample 1 is the substrate 3 of this embodiment, and the first buffer layer 322 and the first The growth temperature of the secondary buffer layer 324 is 400 ° C., and each of the first nitride layers of the first buffer layer 322 is subjected to ion bombardment with a 300 W argon plasma for 20 seconds; Sample 2 is a semi-finished product of the substrate 3, that is, the substrate Only the second buffer layer 324 without ion bombardment is provided on 30. It can be seen from FIG. 18 that the peak of the curve of the sample one is generated, which proves that the present invention can produce good crystals by ion bombarding the first nitride layers of the first buffer layer 322 with the plasma. The curve of sample two has no peaks, which means that the degree of crystallization of the second buffer layer 324 without ion bombardment is lower than that of the first buffer layer 322. Therefore, the second buffer layer 324 can be used as an absorption layer for stress and defects. Relieve the stress and defects caused by the lattice mismatch between the substrate 30 and the first buffer layer 322.

According to the above, the method for manufacturing a substrate for epitaxy of the present invention uses an atomic layer deposition process that requires a lower process temperature to produce an aluminum nitride layer, and uses ion bombardment for each aluminum nitride layer. Like the effect of annealing each aluminum nitride layer, the aluminum nitride layer can be made denser, and the aluminum nitride layers in the buffer layer can be crystallized, thereby obtaining a buffer layer with a high degree of crystallinity.

The above descriptions are only the preferred and feasible embodiments of the present invention, and any equivalent changes made by applying the description of the present invention and the scope of patent application should be included in the patent scope of the present invention.

Claims (16)

A manufacturing method of a substrate for epitaxy, the substrate includes a substrate and a buffer layer; the manufacturing method includes the following steps: A, providing the substrate; B, providing a buffer layer on a surface of the substrate, and providing the The steps of the buffer layer include: B-1, forming a nitride layer using an atomic layer deposition process, wherein the thickness of the nitride layer is between 0.1 and 3 Å; B-2, ion bombarding the nitride layer; and B-3. Repeat steps B-1 and B-2 a plurality of times so that a plurality of the nitride layers are stacked to form the buffer layer having a predetermined thickness. The method for manufacturing a substrate for epitaxy according to claim 1, wherein in step B-2, Ar, N ₂ , H ₂ , He, Ne, NH ₃ , N ₂ / H ₂ , N ₂ O, CF The plasma formed by one of ₄ performs ion bombardment on the nitride layer. The method for manufacturing a substrate for epitaxy according to claim 1, wherein in step B-2, the nitride layer is ion bombarded with a plasma, and the ion bombardment time is 10 seconds or more. The method for manufacturing a base material for epitaxy according to claim 1, wherein in step B-2, the nitride layer is crystallized. The method for manufacturing a substrate for epitaxy according to claim 1, wherein in step B-2, the nitride layer is ion bombarded with a plasma; in step B-3, steps B-1 and B- are repeatedly performed. Before step 2, it includes stopping generating plasma, and within a delay time after stopping generating plasma, step B-1 is executed, wherein the delay time is within 5 seconds. A manufacturing method of a substrate for epitaxy, the substrate includes a substrate and a buffer layer; the manufacturing method includes the following steps: A, providing the substrate; B, setting the buffer layer on a surface of the substrate, the buffer The layer includes at least one first buffer layer and at least one second buffer layer that are stacked; wherein the step of forming the first buffer layer includes: B-1, forming a first nitride layer using an atomic layer deposition process Wherein the thickness of the first nitride layer is between 0.1 and 3 Å; B-2. Ion bombardment of the first nitride layer; and B-3. Repeat steps B-1 and B-2 multiple times. , Making the stacked plurality of first nitride layers constitute a first buffer layer having a first predetermined thickness; wherein the step of forming the second buffer layer includes forming an stacked plurality of first buffer layers using an atomic layer deposition process. Di-nitride layers until the thickness of the second nitride layers reaches a second predetermined thickness to form the second buffer layer. The method for manufacturing a base material for epitaxy according to claim 6, wherein in step B-2, Ar, N ₂ , H ₂ , He, Ne, NH ₃ , N ₂ / H ₂ , N ₂ O, CF The plasma formed by one of ₄ performs ion bombardment on the first nitride layer. The method for manufacturing a substrate for epitaxy according to claim 6, wherein in step B-2, the first nitride layer is ion bombarded with a plasma, and the ion bombardment time is 10 seconds or more. The method for manufacturing a substrate for epitaxy according to claim 6, wherein the buffer layer provided in step B includes a plurality of the first buffer layers and a plurality of the second buffer layers which are alternately stacked. The method for manufacturing a base material for epitaxy according to claim 9, wherein the step of forming each of the second buffer layers further includes, after forming each of the second nitride layers, forming a second nitrogen layer. The compound layer undergoes ion bombardment, and the thickness of each of the second nitride layers is between 0.1 and 3 Å. The method for producing a base material for epitaxy according to claim 9, wherein one of Ar, N ₂ , H ₂ , He, Ne, NH ₃ , N ₂ / H ₂ , N ₂ O, and CF ₄ is used. The formed plasma is subjected to ion bombardment of the second nitride layer. The method for manufacturing a substrate for epitaxy according to claim 6, wherein a material of the first nitride layers is different from a material of the second nitride layers. The method for manufacturing a substrate for epitaxy according to claim 6, wherein the materials of the first nitride layers and the second nitride layers are the same. The method for manufacturing a base material for epitaxy according to claim 6, wherein in step B-2, the first nitride layer is crystallized. The method for manufacturing a substrate for epitaxy according to claim 6, wherein in step B-2, the first nitride layer is ion bombarded with a plasma; step B-3 is repeatedly performed in steps B-1, Before B-2, including stopping plasma generation, and within a delay time after stopping plasma generation, step B-1 is executed, wherein the delay time is within 5 seconds. The method for manufacturing a substrate for epitaxy according to claim 6, wherein in step B, the second buffer layer is provided before the surface of the substrate, and the second buffer layer is not subjected to ion bombardment.