Method for manufacturing a semiconductor substrate

Abstract

The present invention provides a method for fabricating a semiconductor substrate. The method includes performing two laser cuts on the semiconductor substrate. The first laser cut produces a guide layer in the semiconductor substrate, the guide layer including a plurality of first holes arranged at intervals. The second laser cut produces a plurality of second holes at the depth of the guide layer, the second holes being smaller than the first holes. The plurality of second holes and the plurality of first holes form a continuous structure to form a peeling layer. The method then undergoes a process of spinning and cooling, and finally, the substrate is peeled off based on the peeling layer. The method utilizes non-physical contact laser cutting technology, generating less stress. The two-step laser cutting significantly reduces the number of large holes in the peeling layer, thereby avoiding the problem of semiconductor substrate cracking and scrapping. Furthermore, the method produces a thinner damaged layer during the substrate fabrication process, thereby reducing polishing time and improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a method for manufacturing a semiconductor substrate. Background Art

[0002] Currently, the processing of nitride substrates such as GaN and AlN generally requires a process of hydride vapor phase epitaxy (HVPE) crystal growth, wire cutting, thinning, annealing, and polishing, of which the main mechanism for the cutting, grinding, and polishing processes is mechanical processing. However, the residual stress of nitride crystals such as GaN and AlN grown by hydride vapor phase epitaxy is large, and traditional mechanical processing also produces large stress. The combination of the two makes the crystals extremely easy to break during the cutting process, resulting in a reduction in yield. In addition, the wire cutting process will produce a large cutting loss, the loss thickness can even exceed 100um, reaching 20% ​​of the crystal thickness. Finally, the damage layer produced by mechanical processing is thick, even reaching more than 30um. However, the polishing removal rate of nitrides such as GaN and AlN is very low, so the polishing process requires at least 30 hours, resulting in reduced production efficiency. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the present invention proposes a method for manufacturing a semiconductor substrate, wherein the semiconductor substrate is first laser cut, including a first laser cutting and a second laser cutting, wherein the first laser cutting obtains a guide layer in the semiconductor substrate, the guide layer including a plurality of first holes arranged at intervals, and the second laser cutting obtains a plurality of second holes at the depth of the guide layer, the size of the second holes being smaller than the first holes, and the plurality of second holes and the plurality of first holes forming a continuous structure to form a peeling layer, and then the substrate is peeled off based on the peeling layer through a spinning treatment and a cooling treatment. The present invention adopts non-physical contact laser cutting technology, which generates less stress; and the laser cutting is carried out in two steps, which greatly reduces the number of large-sized holes in the peeling layer, thereby avoiding the problem of semiconductor substrate cracking and scrapping; in addition, the damage layer generated in the substrate manufacturing process of the present invention is relatively thin, thereby reducing polishing time and improving production efficiency.

[0004] To achieve the above-mentioned and other related objectives, the present invention provides a method for manufacturing a semiconductor substrate, comprising the following steps:

[0005] S1: providing a substrate;

[0006] S2: performing a first laser cutting on the substrate to form a guide layer in the substrate, wherein the guide layer includes a plurality of first holes arranged at intervals;

[0007] S3: performing a second laser cutting on the substrate to form a peeling layer at a depth of the guide layer, wherein the peeling layer includes a plurality of second holes, wherein the second holes are smaller than the first holes, and the plurality of second holes and the plurality of first holes form a continuous structure to form the peeling layer;

[0008] S4: performing a spin-coating process on the substrate to form a flat adhesive film on the surface of the substrate;

[0009] S5: Cooling the substrate and performing a stripping process on the substrate based on the stripping layer.

[0010] Optionally, in step S1, the substrate is a nitride substrate.

[0011] Optionally, the nitride substrate is made by a hydride vapor phase epitaxy method.

[0012] Optionally, in step S2 and step S3, when laser cutting is performed, the substrate is laser scanned along grid-shaped scanning lines or concentric circular scanning lines.

[0013] Optionally, a thickness d1 of the first hole in the thickness direction of the substrate is between 1 μm and 100 μm.

[0014] Optionally, a thickness d2 of the second hole in the thickness direction of the substrate is between 0.1 μm and 10 μm.

[0015] Optionally, in step S4, the thermal expansion coefficient of the flat film is less than 10 6 / ℃.

[0016] Optionally, in step S5, the substrate is cooled at a cooling rate of 0.5°C / s to 20°C / s, and the substrate is cooled to -183°C to 100°C.

[0017] Optionally, the method further includes polishing the substrate after the stripping process.

[0018] Optionally, the thickness d3 removed from the substrate by the polishing process is half of the thickness d1 of the first hole in the thickness direction of the substrate.

[0019] The method for manufacturing a semiconductor substrate of the present invention has at least the following beneficial effects:

[0020] The present invention proposes a method for fabricating a semiconductor substrate. First, the semiconductor substrate is laser cut, including a first laser cut and a second laser cut. The first laser cut forms a guide layer in the semiconductor substrate, the guide layer including a plurality of first holes arranged at intervals. The second laser cut forms a plurality of second holes at the depth of the guide layer. The second holes are smaller than the first holes, and the plurality of second holes form a continuous structure with the plurality of first holes to form a peeling layer. The substrate is then subjected to a spinning treatment and a cooling treatment, and finally, the substrate is peeled based on the peeling layer. The present invention utilizes non-physical contact laser cutting technology, which generates less stress. The laser cutting is performed in two steps, significantly reducing the number of large holes in the peeling layer, thereby avoiding the problem of semiconductor substrate cracking and scrapping. In addition, the present invention produces a thinner damage layer during the substrate fabrication process, thereby reducing polishing time and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Shown is a flow chart of a method for manufacturing a semiconductor substrate provided by an embodiment.

[0022] Figure 2 Shown is a schematic structural diagram of the substrate provided in step S1 of the embodiment.

[0023] Figure 3 A schematic diagram showing a grid-shaped laser scanning pattern provided in an embodiment is shown.

[0024] Figure 4 A schematic diagram showing a concentric circular laser scanning pattern provided in an embodiment is shown.

[0025] Figure 5 Shown is a schematic structural diagram of the guide layer in step S2 of the embodiment.

[0026] Figure 6 It is a schematic structural diagram of the peeling layer in step S3 of the embodiment.

[0027] Figure 7 It is a schematic structural diagram of forming a flat film of liquid glue on the substrate surface in step S4 of the embodiment.

[0028] Figure 8 It is a schematic structural diagram of the peeling obtained in step S5 of the embodiment.

[0029] Component number description

[0030] 10 substrate

[0031] 20 scan lines

[0032] 11. Guide Layer

[0033] 12 Peeling Layer

[0034] 110 First Hole

[0035] 120 Second Hole

[0036] 30 flat film

[0037] 100 peeling DETAILED DESCRIPTION

[0038] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0039] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Although the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation, the form, quantity, positional relationship and proportion of each component in actual implementation can be changed at will under the premise of realizing the technical solution of this party, and the component layout form may also be more complicated.

[0040] Example

[0041] This embodiment provides a method for manufacturing a semiconductor substrate. Figure 1 As shown, the following steps are included:

[0042] S1: providing a substrate;

[0043] like Figure 2 As shown, a substrate 10 is provided. In this embodiment, substrate 10 is a nitride substrate, which is produced by hydride vapor phase epitaxy (HVPE). As an example, the nitride substrate can be a gallium nitride substrate, an aluminum nitride substrate, or an indium nitride substrate. In this embodiment, a gallium nitride substrate is used as an example for description.

[0044] In this embodiment, the hydride vapor phase epitaxial growth of a gallium nitride substrate includes the following steps: providing a substrate suitable for epitaxial layer growth, in this embodiment, a sapphire substrate is selected, cleaning and nitriding the surface of the sapphire substrate; growing a gallium nitride single crystal on the surface of the sapphire substrate; cooling and peeling, peeling the gallium nitride single crystal from the sapphire substrate to obtain a substrate 10.

[0045] S2: performing a first laser cutting on the substrate to form a guide layer in the substrate, wherein the guide layer includes a plurality of first holes arranged at intervals;

[0046] As an example, when the substrate 10 is laser cut for the first time, the scanning line of the laser scanning can be any one of a plurality of circular lines or a plurality of line segments or a combination of a plurality of circular lines and a plurality of line segments, for example, Figure 3 As shown, the substrate 10 is laser scanned along the grid-like scanning lines 20, or as shown in FIG. Figure 4 As shown, the laser scans the substrate 10 along concentric circular scan lines 20 .

[0047] As an example, a pulsed laser is used to perform intermittent laser scanning on the substrate 10 along the scanning line 20. During laser operation, the laser beam moves relative to the surface of the substrate 10 at a certain speed and in a specified direction, so that discontinuous laser points at different positions constitute a laser scanning line. Through high-power laser pulses and large scanning intervals, a guide layer 11 is formed inside the substrate 10 to provide directional induction for the second laser cutting in step S3.

[0048] like Figure 5 As shown, the guide layer 11 includes a plurality of first holes 110 arranged at intervals. Figure 5 The first holes 110 are shown as circular. It is understood that in actual operation, the first holes 110 can be any possible shape, such as an ellipse, a polygon, etc. In this embodiment, the thickness d1 of the first holes 110 in the substrate thickness direction is between 1 μm and 100 μm. In actual operation, the corresponding laser pulse energy can be selected according to the size requirements of the first holes 110 in the actual processing process. At the same time, the spacing between the first holes 110 can be adjusted according to the scanning speed and pulse frequency of the laser pulse. In this embodiment, the parameter range of the laser pulse is shown in Table 1 below:

[0049]

[0050] Table 1 Parameter range of laser pulse for the first laser cutting

[0051] Within the pulse parameter range shown in Table 1 above, appropriate pulse parameters are selected to perform the first laser scan on the substrate 10 according to actual needs.

[0052] S3: performing a second laser cutting on the substrate to form a peeling layer at a depth of the guide layer, wherein the peeling layer includes a plurality of second holes, wherein the second holes are smaller than the first holes, and the plurality of second holes and the plurality of first holes form a continuous structure to form the peeling layer;

[0053] As an example, the substrate 10 is laser cut for the second time, and the scanning line of the laser scanning can also be any one of a plurality of circular lines or a plurality of line segments or a combination of a plurality of circular lines and a plurality of line segments. For example, referring to Figure 3 and Figure 4 As shown, the substrate 10 is laser scanned along grid-shaped or concentric circular scanning lines 20 .

[0054] like Figure 6 As shown, a peeling layer 12 is formed at the depth of the guide layer 11 by low-power pulsed laser and dense scanning intervals. The peeling layer 12 includes a plurality of second holes 120. The size of the second holes 120 is smaller than the first holes 110, and the plurality of second holes 120 and the plurality of first holes 110 form a continuous structure to form the peeling layer 12. The second holes 120 can produce a weak connection area to enable the substrate 10 to be completely separated in the subsequent peeling process, which is crucial to the yield of the peeling.

[0055] like Figure 6 As shown, the peeling layer 12 includes a plurality of second holes 120 arranged at intervals. Figure 6 The second holes 120 are shown as circular. It is understood that in actual operation, the second holes 120 can be any possible shape, such as an ellipse, a polygon, etc. In this embodiment, the thickness d2 of the second holes 120 in the substrate thickness direction is between 0.1 μm and 10 μm. In actual operation, the corresponding laser pulse energy can be selected according to the size requirements of the second holes 120 in the actual processing process. At the same time, the spacing between the second holes 120 can be adjusted according to the scanning speed and pulse frequency of the laser pulse. In this embodiment, the parameter range of the laser pulse is shown in Table 2 below:

[0056]

[0057] Table 2 Parameter range of laser pulse for the second laser cutting

[0058] Within the pulse parameter range shown in Table 2 above, appropriate pulse parameters are selected to perform a second laser scan on the substrate 10 according to actual needs.

[0059] S4: performing a spin-coating process on the substrate to form a flat adhesive film on the surface of the substrate;

[0060] As an example, the glue-spinning process uses the centrifugal force generated by the rotating substrate to evenly spin the glue and spread it onto the surface of the substrate material. It can currently be used to prepare nano- or micron-level film layers. By adjusting the rotation speed of the glue-spinning machine, the glue can be spread to the edge of the base material and reach a predetermined thickness.

[0061] like Figure 7 As shown, by performing a spin-coating process on the substrate 10, a flat adhesive film 30 is formed on the surface of the substrate 10. As an example, the thermal expansion coefficient of the flat adhesive film 30 is less than 10 6Because the substrate 10 is peeled off to form multiple substrates in this embodiment, only one flat adhesive film 30 is required to be formed on the surface of the substrate 10 . In other optional embodiments, when the substrate 10 is peeled off to form two substrates, a flat adhesive film 30 needs to be formed on both the surface and back of the substrate 10 .

[0062] S5: Cooling the substrate and performing a stripping process on the substrate based on the stripping layer.

[0063] As an example, the substrate 10 is cooled at a cooling rate of 0.5°C / s to 20°C / s to a temperature of -183°C to 100°C, and the substrate 10 is subjected to a peeling process based on the peeling layer 12 to obtain a peeling 100, as shown in FIG. Figure 8 By utilizing the difference in thermal expansion between the liquid glue and the gallium nitride material and rapidly cooling the liquid glue, a large stress is generated between the liquid glue and the gallium nitride crystal. The stress is generally released in the weak connection area, that is, the substrate 10 is separated at the peeling layer 12.

[0064] Finally, the substrate 10 after the peeling process is polished, that is, the side of the peeling 100 containing the second hole 120 is polished. As an example, the polishing thickness is determined according to the thickness d1 of the first hole 110 in the thickness direction of the peeling 100. The thickness of the damaged layer on the surface of the peeling 100 is generally d1 / 2. Therefore, the thickness d3 removed by the polishing process is half of the thickness d1 of the first hole 110 in the thickness direction of the substrate. In other optional embodiments, it can also be greater than half of the thickness d1 of the first hole 110 in the thickness direction of the substrate, and is generally less than the thickness of the damaged layer in the traditional grinding process, thereby improving the polishing efficiency and reducing the polishing cost.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for manufacturing a semiconductor substrate, characterized in that: The steps include: S1: providing a substrate; S2: performing a first laser cutting on the substrate to form a guide layer in the substrate, wherein the guide layer includes a plurality of first holes arranged at intervals; S3: performing a second laser cutting on the substrate to form a peeling layer within the depth range of the guide layer, wherein the peeling layer includes a plurality of second holes, wherein the second holes are smaller than the first holes, and the plurality of second holes and the plurality of first holes form a continuous structure to form the peeling layer; S4: performing a spin-coating process on the substrate to form a flat adhesive film on the surface of the substrate; S5: Cooling the substrate and performing a stripping process on the substrate based on the stripping layer.

2. The method for manufacturing a semiconductor substrate according to claim 1, wherein: In step S1, the substrate is a nitride substrate.

3. The method for manufacturing a semiconductor substrate according to claim 2, wherein: The nitride substrate is manufactured by a hydride vapor phase epitaxy method.

4. The method for manufacturing a semiconductor substrate according to claim 1, wherein: In step S2 and step S3, when laser cutting is performed, the substrate is laser scanned along grid-shaped scanning lines or concentric circular scanning lines.

5. The method for manufacturing a semiconductor substrate according to claim 1, wherein: The thickness d1 of the first hole in the thickness direction of the substrate is between 1 μm and 100 μm.

6. The method for manufacturing a semiconductor substrate according to claim 1, wherein: The thickness d2 of the second hole in the thickness direction of the substrate is between 0.1 μm and 10 μm.

7. The method for manufacturing a semiconductor substrate according to claim 1, wherein: In step S4, the thermal expansion coefficient of the flat film is less than 10 6 / ℃.

8. The method for manufacturing a semiconductor substrate according to claim 1, wherein: In step S5, the substrate is cooled at a cooling rate of 0.5°C / s to 20°C / s, and the substrate is cooled to -183°C to 100°C.

9. The method for manufacturing a semiconductor substrate according to claim 5, wherein: The method further includes polishing the substrate after the stripping process.

10. The method for manufacturing a semiconductor substrate according to claim 9, wherein: The thickness d3 removed from the substrate by the polishing process is half of the thickness d1 of the first hole in the thickness direction of the substrate.

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