CN115816262A - III-V nitride wafer N-polar surface single-side polishing method and III-V nitride wafer - Google Patents

III-V nitride wafer N-polar surface single-side polishing method and III-V nitride wafer Download PDF

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CN115816262A
CN115816262A CN202211604892.7A CN202211604892A CN115816262A CN 115816262 A CN115816262 A CN 115816262A CN 202211604892 A CN202211604892 A CN 202211604892A CN 115816262 A CN115816262 A CN 115816262A
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nitride wafer
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陈吉湖
吉玉宁
尚娟
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Suzhou Nanowin Science And Technology Co ltd
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Abstract

The invention provides a single-side polishing method for an N-polar surface of a III-V group nitride wafer and the III-V group nitride wafer, wherein the single-side polishing method for the N-polar surface of the III-V group nitride wafer comprises the following steps: providing a III-V nitride wafer, wherein the III-V nitride wafer is oriented to a (0001) plane wafer, and the chamfer angle of the (0001) plane towards the direction of an M plane is 0.2-10 degrees; polishing the N-polar surface of the III-V nitride wafer by adopting nano-scale polishing solution with the pH value of 7-8,wherein, the polishing process parameters are as follows: the polishing pressure is 140-220g/cm 2 And the rotation speed of the polishing disk is 25-35rpm, so that the root mean square of the surface roughness of the N-polar surface of the III-V nitride wafer is smaller than a first preset threshold value. The invention has the advantages that the finally prepared III-V group nitride wafer has low surface roughness and few lattice defects.

Description

III-V nitride wafer N-polar surface single-side polishing method and III-V nitride wafer
Technical Field
The invention relates to the technical field of III-V nitride manufacturing, in particular to a single-side polishing method for an N-polar surface of a III-V nitride wafer and the III-V nitride wafer.
Background
GaN is a iii-v compound semiconductor material. Compared with the Ga polarity III-V nitride wafer, the N polarity III-V nitride wafer has different polarities, surface dangling bonds and surface reconstruction modes, can realize a plurality of novel device structures, and obtains performances which are not possessed by the Ga polarity wafer. The N-polar III-V nitride wafer has the characteristics of low contact resistance and high 2DEG threshold by virtue of the characteristic that the polarity of the N-polar III-V nitride wafer is opposite to that of the traditional Ga-polar III-V nitride wafer, and has great advantages in the aspects of high-frequency and high-power microwave wafer tubes, enhancement devices, sensors and the like.
However, the N-polar surface of the III-V nitride wafer has problems of poor chemical stability, susceptibility to corrosion, difficulty in polishing, susceptibility to defects on the epitaxial surface, large surface roughness, and the like, and most of the above problems are determined by the properties of the N-polar surface. The problem of grinding and polishing the N-polar surface of the III-V nitride wafer can be solved by controlling the pressure during grinding or selecting a neutral silicon dioxide polishing solution and controlling the polishing rate. The good polishing effect can ensure that the roughness of the surface of the III-V group nitride wafer is smaller, and the surface of the III-V group nitride wafer is flatter, so that the III-V group nitride wafer has great technical significance for eliminating heat effect and lattice defects. In the prior art, the polishing of the surface of the III-V nitride wafer comprises two process steps of mechanical polishing and Chemical Mechanical Polishing (CMP), the surface roughness root mean square (Ra) of the obtained III-V nitride wafer can only reach 0.6nm, and the adaptability to the beveling angle of the (0001) plane of the crystal plane of the III-V nitride wafer is poor.
In view of the above, there is a need for an improved method for polishing the N-polar side of a group III-V nitride wafer and a group III-V nitride wafer of the prior art to solve the above problems.
Disclosure of Invention
The invention aims to disclose a single-side polishing method for an N-polar surface of a III-V nitride wafer and a III-V nitride wafer, which are used for reducing the root mean square of the surface roughness of the N-polar surface of the III-V nitride wafer and obtaining the III-V nitride wafer with low surface roughness and less crystal lattice defects.
To achieve one of the above objects, the present invention provides a method for polishing an N-polar side single face of a group III-V nitride wafer, comprising:
providing a III-V nitride wafer, wherein the III-V nitride wafer is oriented to a (0001) plane wafer, and the chamfer angle of the (0001) plane towards the direction of an M plane is 0.2-10 degrees;
and polishing the N polar surface of the III-V group nitride wafer by adopting nano-scale polishing solution with the pH value of 7-8, wherein the polishing process parameters are as follows: the polishing pressure is 140-220g/cm 2 And the rotation speed of the polishing disk is 25-35rpm, so that the root mean square of the surface roughness of the N-polar surface of the III-V nitride wafer is smaller than a first preset threshold value.
As a further improvement of the invention, when the chamfer angle is changed within 0.2-10 DEG under the condition of constant polishing pressure, the polishing rate is increased by 16-20nm/min for every 1 DEG increment of the chamfer angle along with the increment of the chamfer angle.
As a further improvement of the invention, before polishing the N-polar surface of the III-V nitride wafer, the method further comprises the following steps: and carrying out multiple times of single-side thinning treatment on the III-V group nitride wafer by adopting an abrasive and a grinding device so as to enable the thickness of the III-V group nitride wafer to be smaller than a second preset threshold value.
As a further improvement of the present invention, the performing, with an abrasive and a polishing apparatus, a plurality of single-side thinning processes on the III-V nitride wafer to make the thickness of the III-V nitride wafer smaller than a second preset threshold value includes: carrying out primary single-side thinning treatment on the III-V group nitride wafer, and thinning the Ga polar surface of the III-V group nitride wafer by adopting a first grinding agent and a first grinding device, wherein the technological parameters of the primary single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotation speed of the grinding disc is 20-50rpm, and the total thickness deviation in the plane is<5 μm, and the second preset threshold value is 390 μm.
As a further improvement of the present invention, the performing, with an abrasive and a polishing device, a plurality of single-side thinning processes on the III-V nitride wafer to make the thickness of the III-V nitride wafer smaller than a second preset threshold value further comprises: and performing secondary single-side thinning treatment on the III-V group nitride wafer, and thinning the N-polar surface of the III-V group nitride wafer by adopting a first grinding agent and a first grinding device, wherein the technological parameters of the secondary single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotation speed of the grinding disc is 20-50rpm, and the total thickness deviation in the plane is<5 μm, and the second preset threshold is 380 μm.
As a further improvement of the invention, the first grinding agent is boron carbide powder or silicon oxide powder, and the particle size of the boron carbide powder or the silicon oxide powder is 15-25 μm.
As a further improvement of the present invention, the performing, with an abrasive and a polishing device, a plurality of single-side thinning processes on the III-V nitride wafer to make the thickness of the III-V nitride wafer smaller than a second preset threshold value further comprises: and carrying out third single-side thinning treatment on the III-V group nitride wafer, and thinning the N-polar surface of the III-V group nitride wafer by adopting a second grinding agent and a second grinding device, wherein the technological parameters of the third single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotating speed of the grinding disc is 20-50rpm,deviation of total thickness in plane<3 μm, and the second preset threshold is 370 μm.
As a further improvement of the invention, the second grinding agent is a diamond grinding fluid, and the particle size of the diamond grinding fluid is 5-10 μm; the second grinding device is a resin copper disc.
As a further improvement of the present invention, the performing, with an abrasive and a polishing device, a plurality of single-side thinning processes on the III-V nitride wafer to make the thickness of the III-V nitride wafer smaller than a second preset threshold value further comprises: performing fourth single-side thinning treatment on the III-V group nitride wafer, and thinning the N-polar surface of the III-V group nitride wafer by adopting a third grinding device, wherein the technological parameters of the fourth single-side thinning treatment are as follows: the grinding pressure is 40-200g/cm 2 The rotating speed of a grinding disc is 25-50rpm, and the total thickness deviation in the plane is<2 μm, root mean square of surface roughness of N-polar surface<2.0nm, and the second preset threshold is 360 μm.
As a further improvement of the invention, the third grinding device is embedded with diamond of 1-3 μm.
As a further improvement of the invention, the N-polar surface of the III-V nitride wafer is polished by adopting the nano-scale polishing solution with the pH value of 7-8 and combining a soft medium hair polishing pad, wherein the polishing process parameters are as follows: the polishing pressure was 200g/cm 2 The polishing disk rotating at 30rpm for total thickness deviation in plane<2 μm, the first preset threshold being 0.2nm.
As a further improvement of the invention, the nano-scale polishing solution with the pH value of 7-8 is prepared by adding oxalic acid into an alkaline solution with the pH value of 10-12 and mixing; wherein the alkaline solution is a solution containing 30% by mass of silica particles having a particle diameter of 80-99nm
Based on the same inventive concept, the present invention also discloses a group III-V nitride wafer,
the III-V nitride wafer is prepared by adopting the single-side polishing method for the N-polar surface of the III-V nitride wafer, the III-V nitride wafer is oriented to a (0001) surface wafer, the chamfer angle of the (0001) surface towards the M surface direction is 0.2-10 degrees, and the root mean square of the surface roughness of the N-polar surface of the III-V nitride wafer is smaller than a first preset threshold value.
As a further refinement of the present invention, the first predetermined threshold is 0.2nm and the III-V nitride wafer has a size of 2 inches to 8 inches.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a single-side polishing method for an N-polar surface of a III-V nitride wafer, which is characterized in that the N-polar surface of the III-V nitride wafer is polished by adopting nano-grade polishing solution with the pH value of 7-8, and the polishing pressure is 140-220g/cm 2 And the rotation speed of the polishing disk is 25-35rpm, so that the root mean square of the roughness of the N polar surface of the III-V nitride wafer is less than 0.2nm. The polishing method can obtain single-side polishing of the N-polar surface of the III-V group nitride wafer, and can further reduce the roughness compared with the gallium nitride wafer with the maximum obtainable roughness root mean square of more than 0.6nm in the prior art, wherein the roughness is less than 0.2nm. The polishing method is suitable for N polar surface III-V nitride wafers with (0001) plane wafer orientation, and the prepared III-V nitride wafers have the advantages of low surface roughness of the N polar surface, few lattice defects and the like.
Drawings
FIG. 1 is a schematic flow chart of a method for polishing an N-polar surface of a III-V nitride wafer according to the present invention;
FIG. 2 is a graph showing the effect of boron carbide powder having a particle size of 15 μm as the first abrasive on the surface roughness of the Ga polar surface of a group III-V nitride wafer in the present example at step S102;
FIG. 3 is a surface image of Ga-polar face of the group III-V nitride wafer obtained in step S102;
FIG. 4 is a surface image of the N-polar face of the group III-V nitride wafer obtained in step S105;
fig. 5 is a surface image of the N-polar face of the group III-V nitride wafer obtained in step S106.
Detailed Description
The present invention is described in detail with reference to the embodiments shown in the drawings, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should understand that functional, methodological, or structural equivalents or substitutions made by these embodiments are within the scope of the present invention.
Referring to fig. 1, there is shown a schematic view of a single-side polishing method (hereinafter, or simply "polishing method") for the N-polar side of a group III-V nitride wafer according to the present invention.
The method for polishing the N-polar surface of the III-V nitride wafer on one side comprises the following steps.
Step S101: a group III-V nitride wafer is provided, the group III-V nitride wafer being oriented with a (0001) plane wafer, the off-angle of the (0001) plane toward the direction of the M plane being 0.2 to 10 deg.
Illustratively, in the present embodiment, a group III-V nitride wafer having a crystal plane of (0001) plane oriented at 0.35 ° to M plane and a thickness of 450 μ M is provided. The group III-V nitride wafer is chamfered to have an R-shaped chamfer and a chamfer width of preferably 100 μm, and the Ga-polar surface of the group III-V nitride wafer is waxed by a waxing machine to control the wax layer thickness to 20 μm or less.
Step S102: carrying out primary single-side thinning treatment on the III-V group nitride wafer, and thinning the Ga polar surface of the III-V group nitride wafer by adopting a first grinding agent and a first grinding device, wherein the technological parameters of the primary single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotating speed of the grinding disc is 20-50rpm, and the total thickness deviation in the plane<5 μm and a second preset threshold of 390 μm. Specifically, the first abrasive is boron carbide powder or silicon oxide powder, and the particle size of the boron carbide powder or the silicon oxide powder is 15-25 μm.
As shown in FIG. 2, the surface roughness Ra of the obtained Ga-polar surface can be controlled to be 0.8 to 1.3 μm by using a fine boron carbide powder having a particle size of 15 μm as the first polishing agent. Specifically, in the step, the Ga polar surface of the III-V nitride wafer is subjected to first single-surface thinning treatment by adopting 15-micron boron carbide micro powder, a first grinding device adopts a cast iron disc, and the grinding pressure is 25g/cm 2 The rotational speed of the grinding disc is 20rpm, willThe thickness of the III-V nitride wafer is reduced to 390 mu m, the deviation of the total thickness in a plane is less than 5 mu m, and the deviation of the total thickness after dewaxing is less than 20 mu m.
After the first single-side thinning treatment was completed, the wax layer on the group III-V nitride wafer was cleaned, and after cleaning, the surface roughness Ra of the Ga-polar surface of the group III-V nitride wafer was measured with a Veeco profiler, and as shown in fig. 3, in this example, the root mean square of the surface roughness Ra of the Ga-polar surface of the group III-V nitride wafer was determined to be 729.77nm.
In other embodiments, the grinding pressure is 35g/cm 2 And the rotating speed of the grinding disc is 30rpm to carry out single-side thinning treatment on the III-V group nitride wafer and test the surface roughness Ra of the corresponding Ga polar surface, and the specific operation steps are the same as the above and are not described again.
After this step is completed, the thickness of the group III-V nitride wafer is tested, and the N-polar face of the group III-V nitride wafer is waxed by a waxing machine with the wax layer thickness controlled to be 15 μm or less.
Step S103: and performing secondary single-side thinning treatment on the III-V group nitride wafer, and thinning the N-polar surface of the III-V group nitride wafer by adopting a first grinding agent and a first grinding device, wherein the technological parameters of the secondary single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotating speed of the grinding disc is 20-50rpm, and the total thickness deviation in the plane<5 μm and a second preset threshold of 380 μm.
The operation method is the same as S102, 15 mu m boron carbide powder or silicon oxide powder is selected, the single-side thinning treatment is carried out on the N-polar surface of the III-V group nitride wafer, and the grinding pressure is 25g/cm 2 The thickness of the III-V nitride wafer was reduced to 380 μm at a polishing disk rotation speed of 20rpm, and the total thickness deviation in plane was<5μm。
Step S104: carrying out third single-side thinning treatment on the III-V group nitride wafer, and carrying out single-side thinning treatment on the N-polar surface of the III-V group nitride wafer by adopting a second grinding agent and a second grinding device, wherein the technological parameters of the third single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotating speed of the grinding disc is 20-50rpm, and the total thickness deviation in the plane<3 μm and a second preset threshold of 370 μm. The second grinding agent is diamond grinding liquid, and the grain diameter of diamond is 5-10 μm.
Specifically, in this example, the N-polar face of the group III-V nitride wafer was subjected to single-side thinning treatment using a 6 μm diamond polishing liquid at a polishing pressure of 50g/cm 2 The second polishing apparatus was a resin copper disk, the rotation speed of the polishing disk was 30rpm, and the thickness of the group III-V nitride wafer was reduced to 370 μm, with a total thickness variation in the plane of less than 3 μm.
Step S105: performing fourth single-side thinning treatment on the III-V group nitride wafer, and performing single-side thinning treatment on the N-polar surface of the III-V group nitride wafer by adopting a third grinding device, wherein the technological parameters of the fourth single-side thinning treatment are as follows: the grinding pressure is 40-200g/cm 2 The total thickness deviation in the plane at the rotating speed of the grinding disc of 25-50rpm<2 μm, root mean square surface roughness Ra of N-polar surface<2.0nm and a second predetermined threshold of 360 μm. In this example, the third polishing device was a 2 μm diamond-inlaid polishing pad, and the N-polar surface of the III-V nitride wafer was subjected to single-side thinning treatment at a polishing pressure of 40-200g/cm 2 The thickness of the III-V nitride wafer was reduced to 360 μm with a total thickness variation in plane of less than 2 μm at a disk rotation speed of 30 rpm.
In this step, applicants show the grinding pressure versus surface roughness Ra of the N-polar surface of the III-V nitride wafer, as shown in Table II below. As can be seen from Table I, when the grinding pressure is 40-200g/cm 2 The surface roughness Ra of the N-polar surface of the III-V nitride wafer can be controlled within 2.0nm at a polishing pressure of 80g/cm 2 The surface roughness Ra of the N-polar surface is the smallest. Therefore, in this embodiment, the polishing pressure is most preferably 80g/cm 2 . At this time, the surface roughness Ra of the N-polar surface of the III-V nitride wafer was measured by an AFM-D3100 apparatus, and the results of the measurement are shown in Table I, and the surface roughness Ra of the N-polar surface of the III-V nitride wafer was 1.56nm and the surface was free from deep scratches. In other embodiments, a grinding pressure of 50g/cm may be selected 2 . As can be seen from FIG. 4, under otherwise identical conditionsWhen the grinding pressure is 50g/cm 2 The surface roughness Ra of the N-polar surface of the III-V nitride wafer is about 1.8 nm.
Figure BDA0003998215190000081
Watch 1
Step S106: polishing the N-polar surface of the III-V nitride wafer by adopting nano-grade polishing solution with the pH value of 7-8 and combining a soft medium hair polishing pad, wherein the polishing process parameters are as follows: the polishing pressure was 200g/cm 2 The polishing disk rotates at 30rpm, and has an in-plane total thickness deviation<2 μm, the first predetermined threshold being 0.2nm.
In the process of grinding and polishing, because the surface layer of the III-V nitride wafer is removed under the dual action of a chemical reagent and mechanical force, a grinding die, a polishing support and the like can be corroded under the strong acid and strong alkali environment, the die and the polishing support are not used for a long time, so that the polishing treatment needs to be carried out under the weak acid or weak alkali environment, the nitride is difficult to react under the weak acid environment, the polishing is carried out purely by the mechanical force, the pressure can be increased, the polishing time can be prolonged, and when the alkalescent pH value is in the range of 7-8, the nitride (a V group element) can also weakly react with the III group metal under the weak alkali environment, the chemical bond of the IIIV group can be damaged, and the polishing time can be shortened. However, when the pH value of the nano-scale polishing solution is higher than 8, the alkalinity is increased, which is not favorable for long-term use of a grinding mold, a polishing bracket and the like; further, the reaction with the group III metal is accelerated after the increase in the basicity, and the polishing rate is increased to some extent, but the polished surface roughness Ra is easily increased. The pH value of the selected polishing solution is between 7 and 8, and the selected polishing solution is neutral or alkaline.
In this step, applicants show the polishing pressure versus surface roughness Ra of the N-polar surface of a III-V nitride wafer, as shown in Table II below. As can be seen from Table I, when the polishing pressure is 140-220g/cm 2 The Ra of the N-polar surface of the III-V nitride wafer can be controlled within 0.2nm at a polishing pressure of 200g/cm 2 On the other hand, the surface roughness Ra of the N-polar surface of the III-V nitride wafer is the smallest. Therefore, in this step, the polishing pressure is most preferably 200g/cm 2 。
Figure BDA0003998215190000091
Watch two
Specifically, in this embodiment, a nano-scale polishing solution with a pH of 7-8 is used in combination with a soft and medium-haired polishing pad to polish the N-polar surface of the III-V nitride wafer, wherein the polishing process parameters are as follows: the polishing pressure was 200g/cm 2 The polishing disk rotating at 30rpm for total thickness deviation in plane<2 μm. Wherein, the nano-scale polishing solution with the pH value of 7-8 is prepared by adding oxalic acid into an alkaline solution with the pH value of 10-12 and mixing, the alkaline solution is a solution containing 30 mass percent of silicon dioxide particles, and the particle size of the silicon dioxide particles is 80-99nm. At this time, the results of the Ra test of the surface roughness of the N-polar face of the III-V nitride wafer using the AFM-D3100 apparatus are shown in FIG. 5. The surface roughness Ra of the N-polar surface of the III-V nitride wafer was 0.126nm, and the surface of the III-V nitride wafer was free from scratches and had atomic step flows. The group III-V nitride wafer to which the above polishing method is applied includes, but is not limited to, group III-V nitride wafers having a crystal plane with a (0001) plane beveling angle of 0.35 ° toward the M plane, and group III-V nitride wafers having various crystal orientations, such as a (0001) plane beveling angle of 0.35 °, 0.5 °, or 2 °.
The applicant further elaborates the corresponding relationship between the beveling angle and the polishing pressure and rotation speed, and specifically shows the test data and refers to the table three below.
Figure BDA0003998215190000092
Figure BDA0003998215190000101
Watch III
In the polishing process, the pressure is kept unchanged, along with the change of the chamfer angle, the included angle between the III-V nitride wafer with the wafer oriented to be a (0001) plane and an M plane is increased, the stability of chemical bonds between III group elements and V group elements is weakened, the chemical stability of crystals is gradually weakened, the chemical bonds are more easily separated under the same polishing pressure, and the chemical mechanical polishing is more easily realized; however, as the chamfer angle increases to more than 6 °, the chemical bonds between the group III atoms and the group V atoms and the external polishing pressure reach a relative equilibrium, and the polishing rate does not increase all the time, thereby reaching a relatively stable range.
The surface roughness is affected by a change in polishing rate during polishing due to the chamfer angle. When the chamfer angle is increased, the chemical bond stability between atoms becomes weaker, the atoms are more easily corroded to separate from the unit cell to form vacancy defects, and the surface roughness is increased.
Based on the foregoing embodiments, the present invention also provides a group III-V nitride wafer produced by the above-described group III-V nitride wafer N-polar side single-side polishing method. Through carrying out single face thinning processing many times to III-V clan nitride wafer, can reduce the stress accumulation of III-V clan nitride wafer structure inside, reduce the cracked risk of wafer structure that leads to because the lattice mismatch defect, improve the production yield of wafer structure. And then, polishing the wafer after multiple single-side thinning treatments, so that the heat dissipation capability of the III-V nitride wafer during working can be effectively improved.
In this embodiment, the multiple thinning process is mainly for thinning the group III-V nitride wafer to a target thickness, and the first single-side thinning process is for thinning the Ga-polar surface, which can reduce the surface roughness Ra of the Ga-polar surface on the one hand and the Ga-polar surface on the other hand; the second single-face thinning is single-face thinning of the N-polar face, the first single-face thinning and the second single-face thinning are used for improving the thinning rate, the first grinding agent is boron carbide powder or silicon oxide powder, the particle size of the boron carbide powder or the silicon oxide powder is 15-25 mu m, and compared with the third single-face thinning, the grinding agent is larger in particle size and higher in thinning rate. The abrasive used in the third single-side thinning treatment has small particle size, can reduce the surface roughness Ra, and the third single-side thinning treatment also aims at the N-polar surface and achieves the target thickness through the third single-side thinning treatment; the fourth thinning further reduces roughness in preparation for subsequent polishing of the wafer to a low roughness.
The invention provides a single-side polishing method for an N-polar surface of a III-V nitride wafer, which is characterized in that the single-side polishing method for the N-polar surface of the III-V nitride wafer is realized by adopting nano-grade polishing solution with the pH value of 7-8 to polish the single side of the N-polar surface of the III-V nitride wafer, and the polishing pressure is 140-220g/cm 2 And the rotation speed of the polishing disk is 25-35rpm, so that the surface roughness Ra root mean square of the N-polar surface of the III-V nitride wafer is smaller than a first preset threshold value, for example, the surface roughness Ra root mean square is smaller than 0.2nm. The polishing method disclosed in this example was applied to group III-V nitride wafers having N-polar surfaces of various crystal orientations, and the group III-V nitride wafers produced by the polishing method had the advantages of low surface roughness Ra of the N-polar surface, few lattice defects, and good electrical properties.
The above-listed detailed description is only a specific description of a possible embodiment of the present invention, and they are not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included in the scope of the present invention.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (14)

1. A method of polishing a single surface of an N-polar side of a group III-V nitride wafer, comprising:
providing a III-V nitride wafer, wherein the III-V nitride wafer is oriented to a (0001) plane wafer, and the chamfer angle of the (0001) plane towards the direction of an M plane is 0.2-10 degrees;
and polishing the N polar surface of the III-V group nitride wafer by adopting nano-scale polishing solution with the pH value of 7-8, wherein the polishing process parameters are as follows: the polishing pressure is 140-220g/cm 2 And the rotation speed of the polishing disk is 25-35rpm, so that the root mean square of the surface roughness of the N-polar surface of the III-V nitride wafer is smaller than a first preset threshold value.
2. The method of polishing one side of an N-polar surface of a group III-V nitride wafer as set forth in claim 1, wherein when the chamfer angle is varied within 0.2 to 10 ° with the polishing pressure being constant, the polishing rate is increased by 16 to 20nm/min for every 1 ° increase of the chamfer angle.
3. The method of claim 1, wherein prior to polishing the N-polar side of the III-V nitride wafer, further comprising: and carrying out single-side thinning treatment on the III-V group nitride wafer for multiple times by adopting an abrasive and a grinding device so as to enable the thickness of the III-V group nitride wafer to be smaller than a second preset threshold value.
4. The method of claim 3, wherein said subjecting the group III-V nitride wafer to a plurality of single-side thinning processes using an abrasive and a grinding device to make the thickness of the group III-V nitride wafer less than a second predetermined threshold comprises: carrying out primary single-side thinning treatment on the III-V group nitride wafer, and thinning the Ga polar surface of the III-V group nitride wafer by adopting a first grinding agent and a first grinding device, wherein the technological parameters of the primary single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotating speed of the grinding disc is 20-50rpm, and the total thickness deviation in the plane<5 μm, and the second preset threshold value is 390 μm.
5. The method of claim 4, wherein said subjecting the group III-V nitride wafer to a plurality of single-side thinning processes using an abrasive and a grinding device to make the thickness of the group III-V nitride wafer less than a second predetermined threshold value further comprises: and performing secondary single-side thinning treatment on the III-V group nitride wafer, and thinning the N-polar surface of the III-V group nitride wafer by adopting a first grinding agent and a first grinding device, wherein the technological parameters of the secondary single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotating speed of the grinding disc is 20-50rpm, and the total thickness deviation in the plane<5 μm, and the second preset threshold is 380 μm.
6. The method for polishing one side of an N-polar surface of a III-V nitride wafer according to claim 4 or 5, wherein the first abrasive is boron carbide powder or silicon oxide powder, and the particle size of the boron carbide powder or silicon oxide powder is 15 to 25 μm.
7. The method of claim 6, wherein said polishing of said III-V nitride wafer with abrasive and grinding means is carried out on said III-V nitride wafer with a single side of N-polar facePerforming single-side thinning processing for a plurality of times to make the thickness of the III-V nitride wafer smaller than a second preset threshold value, further comprising: and carrying out third single-side thinning treatment on the III-V group nitride wafer, and thinning the N-polar surface of the III-V group nitride wafer by adopting a second grinding agent and a second grinding device, wherein the technological parameters of the third single-side thinning treatment are as follows: the grinding pressure is 15-55g/cm 2 The rotating speed of the grinding disc is 20-50rpm, and the total thickness deviation in the plane<3 μm, and the second preset threshold is 370 μm.
8. The method of polishing one side of an N-polar face of a group III-V nitride wafer according to claim 7, wherein the second abrasive is a diamond slurry having a particle diameter of 5 to 10 μm; the second grinding device is a resin copper disc.
9. The method of claim 7, wherein said subjecting the III-V nitride wafer to a plurality of single-side thinning processes using an abrasive and a grinding device to make the thickness of the III-V nitride wafer less than a second predetermined threshold value further comprises: performing fourth single-side thinning treatment on the III-V group nitride wafer, and thinning the N-polar surface of the III-V group nitride wafer by adopting a third grinding device, wherein the technological parameters of the fourth single-side thinning treatment are as follows: the grinding pressure is 40-200g/cm 2 The rotating speed of the grinding disc is 25-50rpm, and the total thickness deviation in the plane<2 μm, root mean square of surface roughness of N-polar surface<2.0nm, and the second preset threshold value is 360 mu m.
10. The N-polar side single-side polishing method of a group III-V nitride wafer according to claim 9, wherein said third grinding means is inlaid with 1 to 3 μm of diamond.
11. The method of claim 1, wherein the nano-polishing with pH of 7-8 is performed by the method of polishing the N-polar side of the III-V nitride waferAnd polishing the N-polar surface of the III-V nitride wafer by using the optical liquid in combination with a soft and medium-hair polishing pad, wherein the polishing process parameters are as follows: the polishing pressure was 200g/cm 2 The polishing disk rotating at 30rpm for total thickness deviation in plane<2 μm, the first preset threshold being 0.2nm.
12. The method of claim 1, wherein the nano-sized polishing slurry having a pH of 7 to 8 is prepared by adding oxalic acid to an alkaline solution having a pH of 10 to 12 and mixing; wherein the alkaline solution is a solution containing 30% by mass of silica particles, and the particle size of the silica particles is 80-99nm.
13. A group III-V nitride wafer is characterized in that,
the group III-V nitride wafer N-polar surface single-side polishing method according to any one of claims 1 to 12, which is produced by the group III-V nitride wafer N-polar surface single-side polishing method, wherein the group III-V nitride wafer is oriented in a (0001) plane, the chamfer angle of the (0001) plane toward the M plane direction is 0.2 to 10 °, and the group III-V nitride wafer has a root mean square of surface roughness of the N-polar surface thereof smaller than a first preset threshold value.
14. The group III-V nitride wafer of claim 13, wherein the first predetermined threshold is 0.2nm and the group III-V nitride wafer has a size of 2 inches to 8 inches.
CN202211604892.7A 2022-06-30 2022-12-14 III-V nitride wafer N-polar surface single-side polishing method and III-V nitride wafer Pending CN115816262A (en)

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