Chamfering device and method for gallium oxide wafer

Abstract

The invention discloses a chamfering device and method for a gallium oxide wafer, and relates to the technical field of gallium oxide wafer machining. The device comprises a driving mechanism, a chamfering and grinding mechanism and a liquid spraying nozzle; the chamfer grinding mechanism comprises a grinding wheel, a floating table, a compression spring and a base which are sequentially arranged from top to bottom, the bottom end of the grinding wheel is fixedly connected with the floating table, the top end of the compression spring abuts against the floating table, and the bottom end of the compression spring abuts against the base; the top face of the grinding wheel is provided with a concave arc face, the arc face is provided with an arc-shaped groove distributed in the arc length direction of the arc face, and the cross section of the arc-shaped groove is in an inverted trapezoid shape. And the arc-shaped groove is positioned right below the gallium oxide wafer adsorbed by the vacuum chuck. The method comprises the steps that when the edge of the gallium oxide wafer needing to be chamfered abuts against the arc-shaped groove, the gallium oxide wafer needing to be chamfered is driven by the driving motor to rotate at the rotating speed of 30-100 rpm. The gallium oxide wafer can be effectively prevented from being scrapped in the chamfering process.

Description

Technical Field

[0001] The present invention relates to the technical field of gallium oxide wafer processing, and in particular to a device and method for chamfering a gallium oxide wafer. Background Art

[0002] As an important semiconductor material, gallium oxide has broad application prospects in the field of electronics. However, gallium oxide has some special properties that bring challenges to its processing.

[0003] Gallium oxide is a monoclinic single crystal. Its main characteristics are that the crystal orientations vary greatly and the interplanar spacings vary greatly, resulting in inconsistent mechanical processing strength. When processing gallium oxide crystal faces, different crystal orientations have inconsistent surface characteristics after being processed under the same mechanical pressure. In severe cases, it can lead to surface cleavage and delamination, making the wafer scrapped.

[0004] During the production, transportation, storage, and subsequent processing and use of wafers, the edges are easily affected by external forces such as collision and friction. Wafers are usually fragile, especially gallium oxide wafers, which have easy-to-cleave properties. Sharp edges that have not been chamfered are more likely to break. The inclined step surface formed after chamfering can effectively disperse the external force on the edge and reduce the risk of wafer edge breakage; it can also prevent the concentration of thermal stress and increase the flatness of the epitaxial layer and photoresist layer at the edge of the wafer.

[0005] Chamfer grinding is a process performed on the angle between two crystal orientation surfaces. Due to the differences in the crystal orientation surfaces of gallium oxide, the grinding speeds of the two surfaces are inconsistent under the same mechanical force, resulting in unilateral pressure deviation, causing chip surface collapse and scrapping.

[0006] Traditional wafer chamfering generally uses a concave diamond grinding wheel to grind the edge of the wafer in a point-contact cylindrical grinding process. The wafer and grinding wheel rotate at high speed, the linear speed difference is used to form a grinding force, and the screw drive is used to ensure grinding uniformity, so that the outer circle of the wafer matches the groove of the grinding wheel to achieve wafer chamfering.

[0007] However, for gallium oxide wafers, traditional grinding wheels use grooves on the outside of a rigid base and are electroplated with diamond particles. The grinding groove surface is rough and has high friction. When acting on the chamfer of gallium oxide wafers, during the high-friction lateral reduction process, when the force is greater than the strength of the crystal surface, the wafer surface will peel off and cleave layer by layer along the cleavage direction, resulting in product scrapping. At the same time, traditional chamfering uses a step-feed grinding method, which has a large instantaneous mechanical force when feeding. Acting on fragile and easily cleaved gallium oxide wafers, it will cause the wafer to cleave instantly along the edge cleavage direction.

[0008] In summary, the traditional chamfering process cannot meet the processing requirements of gallium oxide wafers. How to design processing tooling and processes based on the crystal structure of gallium oxide wafers to achieve the chamfering purpose has become a technical problem that needs to be solved urgently. Summary of the invention

[0009] The object of the present invention is to provide a device and method for chamfering a gallium oxide wafer, so as to solve the problems existing in the above-mentioned prior art and avoid cleavage of the gallium oxide wafer during the chamfering process.

[0010] To achieve the above object, the present invention provides the following solutions:

[0011] The present invention provides a chamfering device for a gallium oxide wafer, comprising:

[0012] A driving mechanism, the driving mechanism comprising a driving motor, a connecting rod and a vacuum suction cup, one end of the connecting rod is fixedly connected to the output shaft of the driving motor, the connecting rod is coaxial with the output shaft, the vacuum suction cup is fixedly connected to the other end of the connecting rod, and the vacuum suction cup is connected to a vacuum source through a rotary joint; the vacuum suction cup is used to absorb the gallium oxide wafer that needs to be chamfered;

[0013] A chamfer grinding mechanism, the chamfer grinding mechanism comprises a grinding wheel, a floating platform, a compression spring and a base arranged in sequence from top to bottom, the bottom end of the grinding wheel is fixedly connected to the floating platform, the top end of the compression spring abuts against the floating platform, and the bottom end of the compression spring abuts against the base; the chamfer grinding mechanism also comprises a plurality of vertical guide rods, the bottom ends of the guide rods are fixedly connected to the base, and the floating platform is slidably sleeved on each of the guide rods; a concave arc surface is provided on the top surface of the grinding wheel, an arc-shaped groove distributed along the arc length direction of the arc surface is provided on the arc surface, and the cross section of the arc-shaped groove is an inverted trapezoid; the arc-shaped groove is located directly below the gallium oxide wafer adsorbed by the vacuum suction cup, and the edge of the gallium oxide wafer adsorbed by the vacuum suction cup can abut against the arc-shaped groove;

[0014] A liquid spray nozzle is used to spray grinding liquid into the arc-shaped groove.

[0015] Preferably, the material of the grinding wheel is glass, tin, resin or copper.

[0016] Preferably, the arc-shaped groove has an opening angle of 6.5°-24.5°.

[0017] Preferably, all the guide rods are evenly distributed along the circumference of the floating platform.

[0018] Preferably, the abrasive in the grinding liquid is a spherical ultrafine powder material.

[0019] Preferably, the spherical ultrafine powder material is silicon carbide, aluminum oxide or boron carbide.

[0020] Preferably, the guide rod and the floating platform are in clearance sliding fit.

[0021] Preferably, the central angles of the arc surface and the arc-shaped groove are both 120°.

[0022] Preferably, the radius of the arc-surface groove is equal to the radius to which the gallium oxide wafer needs to be processed.

[0023] The present invention also provides a gallium oxide wafer chamfering method, based on the above gallium oxide wafer chamfering device, comprising the following steps:

[0024] S1, turning on the vacuum source, and using the vacuum suction cup to absorb the gallium oxide wafer that needs to be chamfered, so that the edge of the gallium oxide wafer that needs to be chamfered abuts against the arc-shaped groove;

[0025] S2, driving the gallium oxide wafer to be chamfered to rotate at a speed of 30 rpm-100 rpm by the driving motor, and at the same time, spraying the grinding liquid into the arc-shaped groove by the liquid spray nozzle;

[0026] S3. As the edge of the gallium oxide wafer is gradually ground, the edge of the gallium oxide wafer will gradually match the groove shape of the arc-shaped groove. After all the edges of the gallium oxide wafer match the groove shape of the arc-shaped groove, turn off the drive motor and then remove the chamfered gallium oxide wafer.

[0027] Compared with the prior art, the present invention has achieved the following technical effects:

[0028] The chamfering device and method of the gallium oxide wafer of the present invention can effectively prevent the gallium oxide wafer from being scrapped during the chamfering process. The present invention aims at the problem that the large differences in the crystal orientations of gallium oxide easily lead to surface cleavage and delamination. By selecting a suitable grinding wheel material, groove design and optimizing grinding process parameters, the risk of cleavage and delamination of the gallium oxide wafer during the processing is greatly reduced, thereby effectively reducing the scrapping of the gallium oxide wafer.

[0029] Furthermore, the present invention achieves the ultimate control of the roundness of the wafer within 0.2 mm through optimized processing methods and precise process control, thereby improving the geometric accuracy of the wafer and meeting higher application requirements.

[0030] Furthermore, the present invention takes into account the anisotropy of the gallium oxide single crystal and the crystal plane angle characteristics, and through reasonable design of the grinding wheel groove and grinding process, effectively reduces the generation of crystal plane cracks caused by large friction during the chamfering and lateral cutting process.

[0031] Furthermore, the present invention solves the problems of easy cleavage and easy collapse of gallium oxide wafers during the chamfering process, improves the quality and reliability of the product, and provides a strong guarantee for the wide application of gallium oxide materials in semiconductors and other fields. Since the scrap rate of gallium oxide wafers is reduced, the production cost of gallium oxide wafers can be reduced. At the same time, the use of grinding wheel materials that can be repeatedly trimmed, such as glass, tin, resin copper, etc., further reduces the material cost in the production process. High-quality gallium oxide wafers can meet the needs of more high-end fields, such as high-power electronic devices, deep ultraviolet optoelectronic devices, etc., and expand a broader space for the application of gallium oxide materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 Schematic diagram of the structure of a gallium oxide single crystal;

[0034] Figure 2 It is a structural schematic diagram of the grinding wheel in the present invention;

[0035] Figure 3 It is a schematic diagram of the forces acting when a gallium oxide single crystal contacts the friction surface of a grinding wheel;

[0036] Figure 4 It is a schematic structural diagram of a chamfering device for a gallium oxide wafer of the present invention;

[0037] In the figure: 1. Vacuum suction cup; 2. Gallium oxide wafer; 3. Liquid spray nozzle; 4. Grinding wheel; 5. Floating table; 6. Compression spring; 7. Guide rod; 8. Base; 9. A side; 10. B side; 11. C side; 12. Arc surface; 13. Arc groove. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The object of the present invention is to provide a device and method for chamfering a gallium oxide wafer, so as to solve the problems existing in the above-mentioned prior art and avoid cleavage of the gallium oxide wafer during the chamfering process.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Embodiment 1

[0042] like Figure 1 and Figure 4 As shown, this embodiment provides a chamfering device for a gallium oxide wafer, comprising:

[0043] The driving mechanism includes a driving motor, a connecting rod and a vacuum suction cup 1, one end of the connecting rod is fixedly connected to the output shaft of the driving motor, the connecting rod is coaxial with the output shaft, the vacuum suction cup 1 is fixedly connected to the other end of the connecting rod, and the vacuum suction cup 1 is connected to the vacuum source through a rotary joint; the vacuum suction cup 1 is used to absorb the gallium oxide wafer 2 that needs to be chamfered;

[0044] The chamfer grinding mechanism includes a grinding wheel 4, a floating platform 5, a compression spring 6 and a base 8 which are arranged in sequence from top to bottom. The bottom end of the grinding wheel 4 is fixedly connected to the floating platform 5, the top end of the compression spring 6 abuts against the floating platform 5, and the bottom end of the compression spring 6 abuts against the base 8. The chamfer grinding mechanism also includes a plurality of vertical guide rods 7, the bottom ends of the guide rods 7 are fixedly connected to the base 8, and the floating platform 5 is slidably sleeved on each guide rod 7. The top surface of the grinding wheel 4 is provided with a concave arc surface 12, and the arc surface 12 is provided with an arc groove 13 distributed along the arc length direction of the arc surface 12, and the cross section of the arc groove 13 is an inverted trapezoid. The arc groove 13 is located directly below the gallium oxide wafer 2 adsorbed by the vacuum suction cup 1, and the edge of the gallium oxide wafer 2 adsorbed by the vacuum suction cup 1 can abut against the arc groove 13.

[0045] The liquid spray nozzle 3 is used to spray the grinding liquid into the arc-shaped groove 13.

[0046] It is worth noting that the compression spring 6 is used to support the floating table 5. On the one hand, it realizes light pressure feeding to replace traditional wire feeding, and at the same time is used for shock absorption to avoid mechanical vibration during operation, which causes instantaneous pressure fluctuations on the wafer and causes chip damage.

[0047] In the optional scheme of this embodiment, it is more preferred that the material of the grinding wheel 4 is softer material such as glass, tin, resin copper powder, etc., replacing the traditional electroplated diamond grinding wheel 4, which can ensure that the chip will not be damaged during the operation and can be repeatedly dressed and applied.

[0048] In the optional solution of this embodiment, it is more preferred that the groove opening angle of the arc-shaped groove 13 is 6.5°-24.5°, because:

[0049] Reference Figure 1The main reason for the anisotropy of gallium oxide single crystals is the large difference in the interplanar spacing of each crystal direction. From the perspective of crystal structure, it is mainly divided into three crystal directions: A, B, and C. Among them, the interplanar spacing of A surface 9 is the largest, with a spacing of 12.45 angstroms; the second largest interplanar spacing is C surface 11, with a spacing of 5.87 angstroms; and finally, the interplanar spacing of B surface 10 is 3.08 angstroms. Due to the large difference in the interplanar spacing of each crystal plane, the maximum mechanical pressure borne by the crystal plane is also very different. As a monoclinic crystal, the angle between A surface 9 and C surface 11 is 76.2°, and the angle between B surface 10 and C surface 11 is 90°. When A surface 9 is used as the main processing surface, one side is 13.8° off from C surface 11; during the chamfering and lateral reduction process, a 13.8° crack will appear on this surface due to the large friction, and the crack surface is C surface 11;

[0050] like Figure 3 As shown, the direction of the force is calculated according to the lattice plane spacing, thereby calculating the groove opening angle of the arc groove 13; the angle between the grinding wheel 4 and the A surface 9 is β, and the pressure of the grinding wheel 4 is F, thereby calculating:

[0051] Pressure on surface A = F*cos(β) / distance between surface A and surface 9 (14.45)

[0052] B surface 10 pressure = F*sin(β) / B surface 10 spacing (3.45)

[0053] Through data simulation calculation, when β=12.9°, the pressure of surface A 9 is consistent with that of surface B 10. At this angle, the stability of surfaces A and B 10 is the best during mechanical grinding. When β<6.5°, the pressure of surface A 9 is more than twice that of surface B 10. If surface A 9 is ground more and surface B 10 is ground less, the support surface of surface B 10 will become smaller and smaller, and the unit pressure will become larger and larger, resulting in cleavage of surface B 10. On the contrary, when β>24.5°, cleavage of surface A 9 will occur. Therefore, the optimal cutting angle of the grinding wheel 4 with surface A 9 is between 6.5° and 24.5°, that is, the slot opening angle design of the arc groove 13 is optimally between 6.5° and 24.5°.

[0054] Regarding the distribution of the guide rods 7: all the guide rods 7 are evenly distributed along the circumference of the floating platform 5, and the guide rods 7 are used to ensure the stable up and down movement of the floating platform 5; and the floating platform 5 is horizontal to ensure the horizontality of the grinding wheel 4; the liquid spray nozzle 3 is connected to the storage tank storing the grinding liquid.

[0055] In the optional scheme of this embodiment, it is more preferred that the abrasive in the grinding liquid is selected from spherical ultrafine powder materials, including silicon carbide, aluminum oxide, boron carbide, etc.

[0056] In this embodiment, the guide rod 7 and the floating platform 5 are in clearance sliding cooperation.

[0057] In the optional solution of this embodiment, it is more preferred that the central angles of the arc surface 12 and the arc-shaped groove 13 are both 120°.

[0058] In the optional solution of this embodiment, it is more preferred that the radius of the groove of the arc surface 12 is equal to the radius that the gallium oxide wafer 2 needs to be processed.

[0059] This embodiment adopts a controlled pressure feeding method to replace the traditional wire feeding method to avoid the gallium oxide wafer 2 being squeezed by the grinding wheel 4 and thus damaged. At the same time, a compression spring 6 is used to play a buffering role during the chamfering process to avoid hard impact on the gallium oxide wafer 2.

[0060] Embodiment 2

[0061] This embodiment provides a method for chamfering a gallium oxide wafer, based on the chamfering device for gallium oxide wafer of the first embodiment, comprising the following steps:

[0062] S1, turning on the vacuum source, using the vacuum suction cup 1 to absorb the gallium oxide wafer 2 that needs to be chamfered, so that the edge of the gallium oxide wafer 2 that needs to be chamfered abuts against the arc-shaped groove 13;

[0063] S2, driving the gallium oxide wafer 2 to be chamfered to rotate at a speed of 30 rpm-100 rpm through a driving motor, and at the same time, spraying abrasive liquid into the arc-shaped groove 13 through a liquid spray nozzle 3;

[0064] S3. As the edge of the gallium oxide wafer 2 is gradually ground, the edge of the gallium oxide wafer 2 will gradually match the groove shape of the arc groove 13. After all the edges of the gallium oxide wafer 2 match the groove shape of the arc groove 13, turn off the drive motor and then remove the chamfered gallium oxide wafer 2.

[0065] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A chamfering device for gallium oxide wafers, characterized in that: include: A driving mechanism, the driving mechanism comprising a driving motor, a connecting rod and a vacuum suction cup, one end of the connecting rod is fixedly connected to the output shaft of the driving motor, the connecting rod is coaxial with the output shaft, the vacuum suction cup is fixedly connected to the other end of the connecting rod, and the vacuum suction cup is connected to a vacuum source through a rotary joint; the vacuum suction cup is used to absorb the gallium oxide wafer that needs to be chamfered; A chamfer grinding mechanism, the chamfer grinding mechanism comprises a grinding wheel, a floating platform, a compression spring and a base arranged in sequence from top to bottom, the bottom end of the grinding wheel is fixedly connected to the floating platform, the top end of the compression spring abuts against the floating platform, and the bottom end of the compression spring abuts against the base; the chamfer grinding mechanism also comprises a plurality of vertical guide rods, the bottom ends of the guide rods are fixedly connected to the base, and the floating platform is slidably sleeved on each of the guide rods; a concave arc surface is provided on the top surface of the grinding wheel, an arc-shaped groove distributed along the arc length direction of the arc surface is provided on the arc surface, and the cross section of the arc-shaped groove is an inverted trapezoid; the arc-shaped groove is located directly below the gallium oxide wafer adsorbed by the vacuum suction cup, and the edge of the gallium oxide wafer adsorbed by the vacuum suction cup can abut against the arc-shaped groove; A liquid spray nozzle is used to spray grinding liquid into the arc-shaped groove.

2. The chamfering device for gallium oxide wafer according to claim 1, characterized in that: The material of the grinding wheel is glass, tin, resin or copper.

3. The gallium oxide wafer chamfering device according to claim 1, characterized in that: The arc-shaped groove has an opening angle of 6.5°-24.5°.

4. The chamfering device for gallium oxide wafer according to claim 1, characterized in that: All the guide rods are evenly distributed along the circumference of the floating platform.

5. The chamfering device for gallium oxide wafer according to claim 1, characterized in that: The abrasive in the grinding liquid is selected from spherical ultrafine powder material.

6. The chamfering device for gallium oxide wafer according to claim 5, characterized in that: The spherical ultrafine powder material is silicon carbide, aluminum oxide or boron carbide.

7. The chamfering device for gallium oxide wafer according to claim 1, characterized in that: The guide rod is in clearance sliding cooperation with the floating platform.

8. The gallium oxide wafer chamfering device according to claim 1, characterized in that: The central angles of the arc surface and the arc-shaped groove are both 120°.

9. The gallium oxide wafer chamfering device according to claim 1, characterized in that: The radius of the arc surface groove is equal to the radius that the gallium oxide wafer needs to be processed to.

10. A method for chamfering a gallium oxide wafer, characterized in that: The chamfering device for a gallium oxide wafer according to any one of claims 1 to 9 comprises the following steps: S1, turning on the vacuum source, and using the vacuum suction cup to absorb the gallium oxide wafer that needs to be chamfered, so that the edge of the gallium oxide wafer that needs to be chamfered abuts against the arc-shaped groove; S2, driving the gallium oxide wafer to be chamfered to rotate at a speed of 30 rpm-100 rpm by the driving motor, and at the same time, spraying the grinding liquid into the arc-shaped groove by the liquid spray nozzle; S3. As the edge of the gallium oxide wafer is gradually ground, the edge of the gallium oxide wafer will gradually match the groove shape of the arc-shaped groove. After all the edges of the gallium oxide wafer match the groove shape of the arc-shaped groove, turn off the drive motor and then remove the chamfered gallium oxide wafer.

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