Device and method for chemically and mechanically polishing diamond substrate with assistance of double-modified multi-energy field

Abstract

The invention discloses a device and a method for chemically and mechanically polishing a diamond substrate under the assistance of double modified multi-energy fields. By means of energy application and ultrasonic cavitation of ultrasonic vibration to a polishing solution and dual modification of strong ultraviolet light to a polishing disc and a diamond substrate, on the premise that the surface quality of polished diamond is guaranteed, the removal rate of a diamond polishing material is increased by increasing the mechanical removal rate, and the surface quality of the polished diamond is guaranteed. The problem that the chemical mechanical polishing material removal rate of the diamond substrate is low is solved. In the machining process, a polishing solution circulating system keeps that a polishing solution infiltrates a diamond substrate, the surfaces of the diamond and a polishing disc are subjected to oxidation modification, and an oxidation layer on the surface of the diamond is removed under the coupling action of ultrasonic, photocatalytic oxidation, electrochemical corrosion and mechanical grinding and polishing removal. Double modification of the diamond substrate and the polishing disc is achieved, the oxidation rate and the mechanical removal rate of the diamond substrate are increased, and the material removal rate and the polishing quality are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of diamond polishing, and in particular to a device and method for double-modified multi-energy field assisted chemical mechanical polishing of a diamond substrate. Background Art

[0002] With the rapid development of science and technology, integrated circuits have been widely infiltrated into all walks of life. The demand for integrated circuit chips is constantly increasing. Power electronic devices are accelerating towards high power, easy to drive and high frequency. Due to the limitations of material properties, materials such as silicon are difficult to adapt to this work requirement. Diamond materials have become a new generation of semiconductor materials with great development potential due to their excellent physical, optical and mechanical properties such as high breakdown voltage, high thermal conductivity and wide energy band. In order to achieve global flatness and high surface quality, chemical mechanical polishing is currently the most widely used polishing method. However, due to the extremely strong chemical inertness and high hardness of diamond, the efficiency of chemical surface modification is extremely low, resulting in extremely low material removal rate of chemical mechanical polishing, which is difficult to adapt to large-scale application requirements.

[0003] The application of multi-energy field assisted chemical action to achieve material surface modification is a breakthrough in improving the polishing material removal rate. Ultraviolet irradiation can promote the formation of electron-hole pairs on the surface of diamond wafers. On this basis, applying an electric field can promote the separation of electron-hole pairs, so that the hole oxidation wafer surface forms an oxide layer with lower hardness. However, due to the extremely strong chemical inertness of diamond, the oxidation modification reaction rate is still slow. At the same time, processing diamond substrates by sapphire polishing discs can effectively improve the material removal rate, but the corresponding flatness and surface roughness are low. Ultrasonic action causes the abrasive particles in the polishing liquid to continuously impact the wafer surface, forming a local stress zone on the wafer surface, which promotes the oxidation process of the wafer surface under the action of stress. Ultraviolet irradiation of the sapphire polishing disc surface can form a modified surface with a hardness between the oxide layer and the diamond substrate, ensuring the roughness and flatness requirements of the wafer surface under the condition of high material removal rate. Based on this, it is of great significance to explore a device and method for double-modified multi-energy field assisted chemical mechanical polishing of diamond substrates for the polishing of diamond substrates. Summary of the invention

[0004] In view of the above-mentioned technical difficulties of low material removal rate in polishing of diamond substrates and difficulty in achieving a constant surface quality and material removal rate, a device and method for double-modified multi-energy field assisted chemical mechanical polishing of diamond substrates are provided.

[0005] The technical means adopted by the present invention are as follows:

[0006] A device for double-modified multi-energy field assisted chemical mechanical polishing of diamond substrates, comprising a mounting frame, an ultrasonic electric loading unit, a light-applying polishing disk unit and a strong ultraviolet light circumferential irradiation unit, wherein the light-applying polishing disk unit is mounted on the mounting frame, the ultrasonic electric loading unit and the strong ultraviolet light circumferential irradiation unit are mounted at a position of the frame higher than the light-applying polishing disk unit, the light-applying polishing disk unit comprises a liquid storage tank for containing polishing liquid and a polishing disk for completing wafer polishing, an ultraviolet light source is arranged below the light-applying polishing disk unit, and a photoelectrolysis cell is formed based on the ultraviolet light source, the ultrasonic electric loading unit and the polishing liquid; the ultrasonic electric loading unit is movably mounted on the mounting frame, and is used to realize that a relatively fixed wafer contacts the polishing disk under the action of ultrasound, and the strong ultraviolet light circumferential irradiation unit is movably mounted on the mounting frame, and is used to provide strong ultraviolet light irradiation of a preset path to modify the polishing disk.

[0007] Furthermore, the mounting frame is arranged in the machine tool, and comprises a base frame and a working frame for supporting the ultrasonic electric loading unit and the strong ultraviolet light circular irradiation unit, and the outside of the mounting frame is sleeved with a machine tool shell.

[0008] Furthermore, the ultrasonic electric loading unit includes a spindle motor, an ultrasonic application unit and a conductive adsorption plate connected in sequence, the conductive adsorption plate is used to complete the adsorption of the chip to be processed in a working state, the ultrasonic electric loading unit is movably mounted on the mounting frame through an ultrasonic electric loading unit position adjustment device, the ultrasonic electric loading unit position adjustment device includes an ultrasonic electric loading unit y-direction lead screw platform and an ultrasonic electric loading unit z-direction lead screw platform, the back side of the ultrasonic electric loading unit y-direction lead screw platform is mounted on the mounting frame, the ultrasonic electric loading unit z-direction lead screw platform is mounted on the ultrasonic electric loading unit y-direction lead screw platform, and the ultrasonic electric loading unit is mounted on the ultrasonic electric loading unit z-direction lead screw platform through the mounting frame.

[0009] Furthermore, the strong ultraviolet light circumferential irradiation unit comprises an L-shaped bracket, an ultraviolet light irradiation partition and a strong ultraviolet light source, the strong ultraviolet light source is mounted on the L-shaped bracket, the non-working surface of the strong ultraviolet light source is covered by the ultraviolet light irradiation partition, the strong ultraviolet light circumferential irradiation unit is movably mounted on the mounting frame through a strong ultraviolet light circumferential irradiation unit position adjustment device, the strong ultraviolet light circumferential irradiation unit adjustment device comprises a circumferential irradiation unit z forward lead screw platform, a circumferential irradiation unit z backward lead screw platform, ... backward lead screw platform, a The circumferential irradiation unit comprises a y-direction screw platform and an x-direction screw platform of the circumferential irradiation unit, the z-forward screw platform of the circumferential irradiation unit and the z-rearward screw platform of the circumferential irradiation unit are respectively installed on two vertical mounting frames, the x-direction screw platform of the circumferential irradiation unit is connected with the z-forward screw platform of the circumferential irradiation unit and the z-rearward screw platform of the circumferential irradiation unit through a U-shaped bracket, the y-direction screw platform of the circumferential irradiation unit is connected with the x-direction screw platform of the circumferential irradiation unit, and the L-shaped bracket is connected to the y-direction screw platform of the circumferential irradiation unit.

[0010] Furthermore, polishing liquid is injected into the liquid storage tank, and the wall of the polishing tank is higher than the plane where the polishing disk is located. In the working state, the polishing liquid infiltrates the polishing disk, and the output end of the polishing disk spindle motor is connected to the polishing disk.

[0011] The present invention also discloses a polishing method based on the double-modified multi-energy field assisted chemical mechanical polishing diamond substrate device, comprising the following steps:

[0012] S1. The diamond substrate is adsorbed on the polishing head of the two-axis ultrasonic electric loading unit by vacuum, the polishing liquid circulation system is turned on, and the polishing liquid is injected into the liquid reservoir. The wall of the polishing pool is higher than the plane where the polishing disc is located. The polishing liquid infiltrates the polishing disc to complete the polishing pretreatment;

[0013] S2, driving the strong ultraviolet light circular irradiation unit to operate, wherein the strong ultraviolet light circular irradiation unit moves in space along the x, y, and z axes in cooperation with three sets of lead screw modules and corresponding adapter motors, and moves in a circular motion near the surface of the polishing disk, and the strong ultraviolet light is irradiated on the polishing disk in a circular trajectory to modify the polishing disk;

[0014] S3, the polishing disc starts to rotate, and at the same time the ultraviolet light source below is turned on, and the two-axis ultrasonic electric loading unit moves to connect the electric loading device with the polishing pool, and the ultraviolet light source, the electric loading device and the polishing liquid form a photoelectrolytic cell;

[0015] S4. The ultrasonic transducer and amplitude transformer built into the two-axis ultrasonic electric loading unit come into contact with the polishing disk under the action of ultrasound. The polishing disk combines the photoelectrochemical modification, ultrasound and mechanical friction removal in the photoelectrolysis cell to jointly polish the surface of the diamond substrate.

[0016] Furthermore, the step S1 specifically includes the following steps:

[0017] The wafer is attached to a conductive metal plate by vacuum, and the back side of the metal plate is connected to the negative pole of the power supply through a conductive pin;

[0018] The end of the horn is connected to the wafer adsorption ring;

[0019] The polishing liquid circulation system is started, the polishing liquid is injected into the liquid storage tank, the sensor detects the liquid level of the polishing liquid in real time, and when the polishing liquid soaks the polishing disk, the circulation mode is enabled to maintain the liquid level position.

[0020] Furthermore, in the step S2, when the strong ultraviolet light circumferential irradiation unit is in working state, ultraviolet light with a wavelength less than 200 nm may be generated;

[0021] During the working process, the strong ultraviolet light source is first lowered along the z direction to the surface adjacent to the polishing disc, and then the strong ultraviolet light source is irradiated in a circular trajectory through the freedom of movement in the xy direction, where the movement trajectory is shown in the following formula:

[0022]

[0023] Where R1 is the maximum distance that the strong ultraviolet light source moves in the x direction, and R2 is the maximum distance that the strong ultraviolet light source moves in the y direction;

[0024] The diameter of the circular track is smaller than the radius of the polishing disc, and the polishing disc undergoes surface modification under strong ultraviolet light irradiation.

[0025] Furthermore, in step S3, forming a photoelectrolysis cell comprises the following steps:

[0026] The ultraviolet light source is activated, and the ultraviolet light is irradiated upward through the waterproof light-transmitting plate. The polishing disc has evenly distributed light-transmitting holes, and the ultraviolet light is irradiated onto the surface of the wafer adsorbed on the ultrasonic electric loading spindle through the light-transmitting holes on the polishing disc;

[0027] The polishing disk starts rotating motion, and after the motion stabilizes, the two-axis ultrasonic electric loading unit moves so that the ultrasonic electric loading main axis moves down along the z-axis to the surface of the wafer close to the surface of the polishing disk. At this time, the polishing liquid infiltrates the wafer, and the positive electrode of the power supply is connected to the polishing disk through a conductive sheet. The wafer is the cathode and the polishing disk is the anode. The ultraviolet light source, the electric loading device and the polishing liquid form a photoelectrolysis cell, and the wafer surface is oxidatively modified by the strong ultraviolet light.

[0028] Furthermore, the step S4 comprises the following steps:

[0029] Under the control of the two-axis motion system, the two-axis ultrasonic electric loading unit descends along the z-axis to the surface of the wafer and contacts the polishing disk. When powered on, the ultrasonic transducer and the amplitude transformer work, and the two-axis ultrasonic electric loading unit vibrates at high frequency along the z-axis direction. The abrasive particles in the polishing liquid continuously impact the surface of the wafer, and the surface of the wafer contacts the polishing disk intermittently at the ultrasonic frequency. The surface of the diamond substrate is polished under the combined action of photoelectrochemical modification, ultrasound and mechanical friction removal.

[0030] Compared with the prior art, the present invention has the following advantages: during the processing, the polishing liquid circulation system keeps the polishing liquid infiltrating the diamond substrate, the surfaces of the diamond and the polishing disk are both oxidatively modified, and the oxide layer on the diamond surface is removed under the coupling effects of ultrasound, photocatalytic oxidation, electrochemical corrosion, and mechanical grinding and polishing. The present invention realizes dual modification of the diamond substrate and the polishing disk, increases the oxidation rate and mechanical removal rate of the diamond substrate, and improves the material removal rate and polishing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 It is an overall schematic diagram of a double-modified multi-energy field assisted chemical mechanical polishing diamond substrate device of the present invention;

[0033] Figure 2 It is an internal schematic diagram of a double-modified multi-energy field assisted chemical mechanical polishing diamond substrate device of the present invention;

[0034] Figure 3 It is a schematic diagram of a two-axis ultrasonic electric loading unit in a specific embodiment of the present invention;

[0035] Figure 4 It is a schematic diagram of a strong ultraviolet light circumferential irradiation unit in a specific embodiment of the present invention;

[0036] Figure 5 It is a schematic structural diagram of a light-applying polishing disk unit from a first viewing angle in a specific embodiment of the present invention;

[0037] Figure 6 It is a schematic structural diagram of a light-applying polishing disk unit from a second viewing angle in a specific embodiment of the present invention;

[0038] Figure 7 It is a specific workflow diagram of the present invention;

[0039] In the figure: 1. Control room; 2. Transparent observation partition; 3. Polishing room; 4. Working frame; 5. Two-axis ultrasonic electric loading unit; 6. Strong ultraviolet light circumferential irradiation unit; 7. Light application polishing disc unit; 8. Ultrasonic electric loading unit y-direction servo motor; 9. Coupling; 10. Ultrasonic electric loading unit y-direction screw platform; 11. Ultrasonic electric loading unit z-direction servo motor; 12. Coupling; 13. Ultrasonic electric loading unit z-direction screw platform; 14. Conductive slip ring; 15. Spindle motor; 16. Ultrasonic application unit; 17. Conductive adsorption disk; 18. Circumferential irradiation unit z-forward screw platform; 19. U-shaped bracket; 20. Circumferential irradiation unit y-direction screw platform; 21. Circumferential irradiation unit x-direction screw platform; 22. Circumferential irradiation unit z-rearward screw platform; 23. L-shaped bracket; 24. Ultraviolet irradiation partition; 25. Strong ultraviolet light source; 26. Polishing disk; 27. Liquid storage tank; 28. Polishing disk spindle motor; 29. ​​Liquid storage disk; 30. Waterproof light-transmitting plate; 31. Ultraviolet light source. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. 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.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0043] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0044] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0045] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0046] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0047] like Figure 1 to Figure 6As shown, an embodiment of the present invention discloses a device for dual-modified multi-energy field assisted chemical mechanical polishing of a diamond substrate, comprising a mounting frame, an ultrasonic electric loading unit 5, a light-applying polishing disk unit 7 and a strong ultraviolet light circumferential irradiation unit 6, wherein the light-applying polishing disk unit is mounted on the mounting frame, and the ultrasonic electric loading unit and the strong ultraviolet light circumferential irradiation unit 6 are mounted at a position where the frame is higher than the light-applying polishing disk unit 7, and the light-applying polishing disk unit 7 comprises a liquid storage tank 27 for containing a polishing liquid and a polishing disk 26 for completing wafer polishing, and an ultraviolet light source 31 is arranged below the light-applying polishing disk unit 7, and a photoelectrolysis cell is formed based on the ultraviolet light source 31, the ultrasonic electric loading unit 5 and the polishing liquid; the ultrasonic electric loading unit 5 is movably mounted on the mounting frame, and is used to realize that a relatively fixed wafer contacts the polishing disk 26 under the action of ultrasound, and the strong ultraviolet light circumferential irradiation unit 6 is movably mounted on the mounting frame, and is used to provide strong ultraviolet light irradiation of a preset path to modify the polishing disk 26. The ultraviolet light source 31 is disposed below the liquid storage tank 27 , and a waterproof light-transmitting plate 30 is installed at the light opening.

[0048] The liquid storage tray 29 is installed under the polishing disk 26 and cooperates with the cylindrical tube wall of the liquid storage tank 27 to prevent the polishing liquid from penetrating into the working area of ​​the polishing disk spindle motor 28 during operation. At the same time, the bottom cooperates with the waterproof and transparent plate 30 so that the installation position of the ultraviolet light source can be as close to the chip processing surface as possible.

[0049] Based on the above device, the present invention utilizes the energy application of ultrasonic vibration to the polishing liquid and the ultrasonic cavitation effect, and the dual modification effect of strong ultraviolet light on the polishing disk 26 and the diamond substrate, to ensure the surface quality of the polished diamond as a prerequisite, and to increase the diamond polishing material removal rate by increasing the mechanical removal rate, thereby solving the problem of low chemical mechanical polishing material removal rate of the diamond substrate.

[0050] The mounting frame is arranged in the machine tool, including a bottom frame and a working frame 4 for supporting the ultrasonic electric loading unit 5 and the strong ultraviolet light circumferential irradiation unit 6, and the machine tool housing is sleeved on the outside of the mounting frame. The machine tool also includes a control room for controlling processing parameters and a polishing room 3 for installing the above-mentioned devices and mainly used for completing polishing work. A light-transmitting observation partition 2 for observing the polishing process is arranged on one side of the polishing room.

[0051] The ultrasonic electric loading unit 5 includes a spindle motor 15, an ultrasonic applying unit 16 and a conductive adsorption plate 17 which are connected in sequence. The conductive adsorption plate 17 is used to complete the adsorption of the wafer to be processed in a working state. The ultrasonic electric loading unit 5 is movably mounted on the mounting frame through an ultrasonic electric loading unit position adjustment device. The ultrasonic electric loading unit position adjustment device includes an ultrasonic electric loading unit y-direction lead screw platform 10 and an ultrasonic electric loading unit z-direction lead screw platform 13. The back of the ultrasonic electric loading unit y-direction lead screw platform is mounted on the mounting frame, the ultrasonic electric loading unit z-direction lead screw platform is mounted on the ultrasonic electric loading unit y-direction lead screw platform 10, and the ultrasonic applying unit 16 is mounted on the ultrasonic electric loading unit z-direction lead screw platform 13 through a mounting frame. The ultrasonic transducer is connected to the horn and built into the ultrasonic application unit 16. The end of the horn is connected to the wafer adsorption ring. When powered on, the wafer adsorbed on the suction cup can vibrate at an ultrasonic frequency. The ultrasonic electric loading unit y-direction servo motor 8 is connected to the lead screw through a coupling 9. The ultrasonic electric loading unit z-direction servo motor 11 is connected to the lead screw through a coupling 12. A conductive slip ring 14 for power supply is provided at the upper end of the ultrasonic transducer.

[0052] The wafer is mounted on the two-axis ultrasonic electric loading unit 5 and is vacuum-adsorbed on the conductive loading disk 17. The ultraviolet light is directly irradiated on the diamond substrate through the conductive polishing disk 17. At the same time, the strong ultraviolet light circumferential irradiation unit 6 irradiates the polishing disk 26 with strong ultraviolet light. The diamond substrate, polishing liquid and polishing disk 26 form an electrochemical system.

[0053] The center of the upper surface of the polishing disc 26 is taken as the origin of the machine coordinate system, the direction perpendicular to the light-transmitting observation partition 2 is the x-axis direction, the direction along the light-transmitting observation partition 2 is the y-axis direction, and the z-axis is vertically upward along the main axis direction of the polishing disc 26. The ultrasonic electric loading spindle is loaded on a two-axis motion platform that can move on the yz plane, and the two-axis motion platform is composed of a screw platform 10 along the y direction and a screw platform 11 along the z direction respectively;

[0054] Furthermore, the strong ultraviolet light circular irradiation unit comprises an L-shaped bracket 23, an ultraviolet light irradiation partition 24 and a strong ultraviolet light source 25, wherein the strong ultraviolet light source is mounted on the L-shaped bracket, and the non-working surface of the strong ultraviolet light source is covered by the ultraviolet light irradiation partition. The strong ultraviolet light circular irradiation unit is movably mounted on the mounting frame through a strong ultraviolet light circular irradiation unit position adjustment device, and the strong ultraviolet light circular irradiation unit adjustment device comprises a circumferential irradiation unit z forward lead screw platform 18, a circumferential irradiation unit z backward lead screw platform 22, a circular The circumferential irradiation unit y-direction screw platform 20 and the circumferential irradiation unit x-direction screw platform 21, the circumferential irradiation unit z-forward screw platform and the circumferential irradiation unit z-rearward screw platform are respectively installed on two vertical mounting frames, the circumferential irradiation unit x-direction screw platform is connected to the circumferential irradiation unit z-forward screw platform and the circumferential irradiation unit z-rearward screw platform through a U-shaped bracket 19, the circumferential irradiation unit y-direction screw platform is connected to the circumferential irradiation unit x-direction screw platform, and the L-shaped bracket is connected to the circumferential irradiation unit y-direction screw platform.

[0055] In this embodiment, the x-direction screw platform 21 of the circumferential irradiation unit can be adjusted to a certain height, but it cannot exceed the lowest point of the y-direction screw platform 10 of the ultrasonic electric loading unit to prevent interference between the two and affect the operation of the device.

[0056] Polishing liquid is injected into the liquid storage tank, and the wall of the polishing tank is higher than the plane where the polishing disk is located. In the working state, the polishing liquid infiltrates the polishing disk, and the output end of the polishing disk spindle motor 28 is connected to the polishing disk.

[0057] like Figure 7 As shown, the present invention also discloses a polishing method based on the above-mentioned double-modified multi-energy field assisted chemical mechanical polishing device for diamond substrates, comprising the following steps:

[0058] S1. The diamond substrate is adsorbed on the polishing head of the two-axis ultrasonic electric loading unit by vacuum, the polishing liquid circulation system is turned on, and the polishing liquid is injected into the liquid reservoir. The wall of the polishing pool is higher than the plane where the polishing disc is located. The polishing liquid infiltrates the polishing disc to complete the polishing pretreatment;

[0059] S2, driving the strong ultraviolet light circular irradiation unit to operate, wherein the strong ultraviolet light circular irradiation unit moves in space along the x, y, and z axes in cooperation with three sets of lead screw modules and corresponding adapter motors, and moves in a circular motion near the surface of the polishing disk, and the strong ultraviolet light is irradiated on the polishing disk in a circular trajectory to modify the polishing disk;

[0060] S3, the polishing disc starts to rotate, and at the same time the ultraviolet light source below is turned on, and the two-axis ultrasonic electric loading unit moves to connect the electric loading device with the polishing pool, and the ultraviolet light source, the electric loading device and the polishing liquid form a photoelectrolytic cell;

[0061] S4. The ultrasonic transducer and amplitude transformer built into the two-axis ultrasonic electric loading unit come into contact with the polishing disk under the action of ultrasound. The polishing disk combines the photoelectrochemical modification, ultrasound and mechanical friction removal in the photoelectrolysis cell to jointly polish the surface of the diamond substrate.

[0062] Furthermore, the step S1 specifically includes the following steps:

[0063] The wafer is adsorbed on a conductive metal plate by vacuum, and the back side of the metal plate is connected to the negative pole of the power supply through a conductive pin;

[0064] The end of the horn is connected to the wafer adsorption ring;

[0065] The polishing liquid circulation system is started, the polishing liquid is injected into the liquid storage tank, the sensor detects the liquid level of the polishing liquid in real time, and when the polishing liquid soaks the polishing disk, the circulation mode is enabled to maintain the liquid level position.

[0066] Furthermore, in the step S2, when the strong ultraviolet light circumferential irradiation unit is in working state, ultraviolet light with a wavelength less than 200 nm may be generated;

[0067] During the working process, the strong ultraviolet light source is first lowered along the z direction to the surface adjacent to the polishing disc, and then the strong ultraviolet light source is irradiated in a circular trajectory through the freedom of movement in the xy direction, where the movement trajectory is shown in the following formula:

[0068]

[0069] Where R1 is the maximum distance that the strong ultraviolet light source moves in the x direction, and R2 is the maximum distance that the strong ultraviolet light source moves in the y direction;

[0070] The diameter of the circular track is smaller than the radius of the polishing disc, and the polishing disc undergoes surface modification under strong ultraviolet light irradiation.

[0071] Furthermore, in step S3, forming a photoelectrolysis cell comprises the following steps:

[0072] The ultraviolet light source is activated, and the ultraviolet light is irradiated upward through the waterproof light-transmitting plate. The polishing disc has evenly distributed light-transmitting holes, and the ultraviolet light is irradiated onto the surface of the wafer adsorbed on the ultrasonic electric loading spindle through the light-transmitting holes on the polishing disc;

[0073] The polishing disk starts rotating motion, and after the motion stabilizes, the two-axis ultrasonic electric loading unit moves so that the ultrasonic electric loading main axis moves down along the z-axis to the surface of the wafer close to the surface of the polishing disk. At this time, the polishing liquid infiltrates the wafer, and the positive electrode of the power supply is connected to the polishing disk through a conductive sheet. The wafer is the cathode and the polishing disk is the anode. The ultraviolet light source, the electric loading device and the polishing liquid form a photoelectrolysis cell, and the wafer surface is oxidatively modified by the strong ultraviolet light.

[0074] Furthermore, the step S4 comprises the following steps:

[0075] Under the control of the two-axis motion system, the two-axis ultrasonic electric loading unit descends along the z-axis to the surface of the wafer and contacts the polishing disk. When powered on, the ultrasonic transducer and the amplitude transformer work, and the two-axis ultrasonic electric loading unit vibrates at high frequency along the z-axis direction. The abrasive particles in the polishing liquid continuously impact the surface of the wafer, and the surface of the wafer contacts the polishing disk intermittently at the ultrasonic frequency. The surface of the diamond substrate is polished under the combined action of photoelectrochemical modification, ultrasound and mechanical friction removal.

[0076] Example 1

[0077] The present invention provides a device and method for double-modified multi-energy field assisted chemical mechanical polishing of diamond substrates. The device uses a UV light source from USHIO Company to provide UV light with a wavelength between 172nm and 395nm.

[0078] In the process of establishing a device and method for dual-modified multi-energy field-assisted chemical mechanical polishing of diamond substrates in the present invention, first, the diamond substrate is vacuum-adsorbed on the polishing head of the two-axis ultrasonic electric loading unit 5, the polishing liquid circulation system is turned on, and the polishing liquid is injected into the liquid storage tank 27. The wall of the polishing tank is higher than the plane where the polishing disc 26 is located. The polishing liquid soaks the polishing disc and completes the polishing pretreatment. Then, the strong ultraviolet light circumferential irradiation unit 6 is driven to operate. The strong ultraviolet light circumferential irradiation unit 6 can move along the x, y, and z axes in space with the cooperation of three sets of lead screw modules and corresponding adapter motors, and move in a circle near the surface of the polishing disc. The strong ultraviolet light irradiation irradiates the polishing disc in a circular trajectory to modify the polishing disc. Furthermore, the polishing disc 26 starts to rotate, and the ultraviolet light source 31 below is turned on at the same time. The two-axis ultrasonic electric loading unit 5 moves to connect the electric loading device with the polishing pool. The ultraviolet light source 31, the electric loading device and the polishing liquid form a photoelectrolysis cell. Finally, the two-axis ultrasonic electric loading unit 5 has an ultrasonic transducer and a horn built in, and contacts the polishing disc under the action of ultrasound, and the polishing disc combines the photoelectrochemical modification, ultrasound and mechanical friction removal in the photoelectrolysis cell to jointly polish the surface of the diamond substrate. Specifically, the method has the following steps:

[0079] S1, take the center of the upper surface of the polishing disc 26 as the origin of the machine coordinate system, the direction perpendicular to the light-transmitting observation partition 2 is the x-axis direction, the direction along the light-transmitting observation partition 2 is the y-axis direction, and the z-axis is vertically upward along the main axis direction of the polishing disc 26. The ultrasonic electric loading spindle is loaded on a two-axis motion platform that can move in the yz plane, and the two-axis motion platform is composed of a screw platform 10 along the y direction and a screw platform 11 along the z direction respectively;

[0080] S2, the wafer is adsorbed on the conductive metal plate 17 by vacuum, and the back side of the metal plate is connected to the negative electrode of the power supply through a conductive pin;

[0081] S3, the ultrasonic transducer is connected to the horn, which is built into the ultrasonic application unit 16, and the end of the horn is connected to the wafer adsorption ring, which can make the wafer adsorbed on the suction cup vibrate at an ultrasonic frequency under power-on conditions;

[0082] S4, the polishing liquid circulation system is started, the polishing liquid is injected into the liquid storage tank 27, the sensor detects the polishing liquid water level in real time, and when the polishing liquid soaks the polishing plate, the circulation mode is enabled to maintain the liquid level position;

[0083] S5, the strong ultraviolet light source 25 is an ultraviolet light generating device that can generate a wavelength less than 200nm, with an ultraviolet irradiation spacer 24 on the outside, connected to the three-axis motion platform through an L-shaped bracket 23, and the three-axis motion platform is composed of a screw platform 21 along the x direction, a screw platform 19 along the y direction, and a screw platform 22 along the z direction and corresponding adapter motors;

[0084] S6, working process The strong ultraviolet light source 25 is first lowered along the z direction to the surface adjacent to the polishing plate 26, and then the strong ultraviolet light source is irradiated in a circular trajectory through the freedom of movement in the xy direction, wherein the movement trajectory is shown in the following formula:

[0085]

[0086] Where R1 is the maximum distance that the strong ultraviolet light source moves in the x direction, R2 is the maximum distance that the strong ultraviolet light source moves in the y direction, R1 = R2 = 55mm;

[0087] The diameter of the circular track is smaller than the radius of the polishing disc, and the polishing disc undergoes surface modification under strong ultraviolet light irradiation;

[0088] S7, the ultraviolet light source 31 is activated, and the ultraviolet light source 31 is placed below the liquid storage tank 27, and a waterproof light-transmitting plate 30 is installed at the light opening, and the ultraviolet light is irradiated upward through the waterproof light-transmitting plate 30, and the polishing plate 26 is provided with evenly distributed light-transmitting holes, and the diameter of the light-transmitting holes is d=10 mm, and the ultraviolet light is irradiated onto the surface of the wafer adsorbed on the ultrasonic electric loading spindle through the light-transmitting holes on the polishing plate 26;

[0089] S8, the polishing disc 26 starts rotating and waits for it to run for 15 minutes to complete preheating. After the movement is stable, the two-axis ultrasonic electric loading unit 5 moves so that the ultrasonic electric loading main axis moves down along the z-axis to the surface of the wafer close to the surface of the polishing disc 26. At this time, the polishing liquid infiltrates the wafer, and the positive electrode of the power supply is connected to the polishing disc through the conductive sheet. The wafer is the cathode and the polishing disc 26 is the anode. The ultraviolet light source 31, the electric loading device and the polishing liquid form a photoelectrolysis cell, and the wafer surface is oxidized and modified by the strong ultraviolet light.

[0090] S9. Under the control of the two-axis motion system, the two-axis ultrasonic electric loading unit 5 descends along the z-axis to the surface of the wafer and contacts the polishing disk. When powered on, the ultrasonic transducer and the horn work, and the two-axis ultrasonic electric loading unit 5 vibrates at high frequency along the z-axis direction. The abrasive particles in the polishing liquid continuously impact the surface of the wafer, and the surface of the wafer contacts the polishing disk 26 intermittently at the ultrasonic frequency. The surface of the diamond substrate is polished under the combined action of photoelectrochemical modification, ultrasound and mechanical friction removal. The material removal rate measured by the weighing method is significantly improved compared with the chemical mechanical polishing of diamond. The surface roughness and flatness of the diamond substrate after processing meet the requirements. It shows that the device and method for chemical mechanical polishing of diamond substrates assisted by double-modified multi-energy fields proposed in the present invention are reliable.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for chemical mechanical polishing of diamond substrates assisted by double-modified multi-energy fields, characterized in that: It includes a mounting frame, an ultrasonic electric loading unit, a light-applying polishing disk unit and a strong ultraviolet light circumferential irradiation unit, wherein the light-applying polishing disk unit is mounted on the mounting frame, and the ultrasonic electric loading unit and the strong ultraviolet light circumferential irradiation unit are mounted at a position of the frame higher than the light-applying polishing disk unit, the light-applying polishing disk unit includes a liquid storage tank for containing polishing liquid and a polishing disk for completing wafer polishing, an ultraviolet light source is arranged below the light-applying polishing disk unit, and a photoelectrolysis cell is formed based on the ultraviolet light source, the ultrasonic electric loading unit and the polishing liquid; the ultrasonic electric loading unit is movably mounted on the mounting frame, and is used to realize that a relatively fixed wafer contacts the polishing disk under the action of ultrasound, and the strong ultraviolet light circumferential irradiation unit is movably mounted on the mounting frame, and is used to provide strong ultraviolet light irradiation of a preset path to modify the polishing disk.

2. The device for double-modified multi-energy field assisted chemical mechanical polishing of diamond substrate according to claim 1, characterized in that: The mounting frame is arranged in the machine tool, and comprises a base frame and a working frame for supporting the ultrasonic electric loading unit and the strong ultraviolet light circumferential irradiation unit, and the machine tool shell is sleeved on the outside of the mounting frame.

3. The device for double-modified multi-energy field assisted chemical mechanical polishing of diamond substrate according to claim 1, characterized in that: The ultrasonic electric loading unit includes a spindle motor, an ultrasonic application unit and a conductive adsorption plate connected in sequence, the conductive adsorption plate is used to complete the adsorption of the wafer to be processed in a working state, the ultrasonic electric loading unit is movably mounted on the mounting frame through an ultrasonic electric loading unit position adjustment device, the ultrasonic electric loading unit position adjustment device includes an ultrasonic electric loading unit y-direction lead screw platform and an ultrasonic electric loading unit z-direction lead screw platform, the back side of the ultrasonic electric loading unit y-direction lead screw platform is mounted on the mounting frame, the ultrasonic electric loading unit z-direction lead screw platform is mounted on the ultrasonic electric loading unit y-direction lead screw platform, and the ultrasonic electric loading unit is mounted on the ultrasonic electric loading unit z-direction lead screw platform through the mounting frame.

4. The device for double-modified multi-energy field assisted chemical mechanical polishing of diamond substrate according to claim 1, characterized in that: The strong ultraviolet circular irradiation unit comprises an L-shaped bracket, an ultraviolet irradiation partition and a strong ultraviolet light source, wherein the strong ultraviolet light source is mounted on the L-shaped bracket, and the non-working surface of the strong ultraviolet light source is covered by the ultraviolet irradiation partition, and the strong ultraviolet circular irradiation unit is movably mounted on the mounting frame through a strong ultraviolet circular irradiation unit position adjustment device, and the strong ultraviolet circular irradiation unit adjustment device comprises a circumferential irradiation unit z forward lead screw platform, a circumferential irradiation unit z backward lead screw platform, and a circumferential irradiation unit The y-direction screw platform and the x-direction screw platform of the circumferential irradiation unit, the z-forward screw platform of the circumferential irradiation unit and the z-rearward screw platform of the circumferential irradiation unit are respectively installed on two vertical mounting frames, the x-direction screw platform of the circumferential irradiation unit is connected with the z-forward screw platform of the circumferential irradiation unit and the z-rearward screw platform of the circumferential irradiation unit through a U-shaped bracket, the y-direction screw platform of the circumferential irradiation unit is connected with the x-direction screw platform of the circumferential irradiation unit, and the L-shaped bracket is connected to the y-direction screw platform of the circumferential irradiation unit.

5. The device for double-modified multi-energy field assisted chemical mechanical polishing of diamond substrate according to claim 1, characterized in that: Polishing liquid is injected into the liquid storage tank, and the wall of the polishing tank is higher than the plane where the polishing disk is located. In the working state, the polishing liquid infiltrates the polishing disk, and the output end of the polishing disk spindle motor is connected to the polishing disk.

6. A polishing method for a double-modified multi-energy field assisted chemical mechanical polishing diamond substrate device according to any one of claims 1 to 5, characterized in that: The steps include: S1. The diamond substrate is adsorbed on the polishing head of the two-axis ultrasonic electric loading unit by vacuum, the polishing liquid circulation system is turned on, and the polishing liquid is injected into the liquid reservoir. The wall of the polishing pool is higher than the plane where the polishing disc is located. The polishing liquid infiltrates the polishing disc to complete the polishing pretreatment; S2, driving the strong ultraviolet light circular irradiation unit to operate, wherein the strong ultraviolet light circular irradiation unit moves in space along the x, y, and z axes in cooperation with three sets of lead screw modules and corresponding adapter motors, and moves in a circular motion near the surface of the polishing disk, and the strong ultraviolet light is irradiated on the polishing disk in a circular trajectory to modify the polishing disk; S3, the polishing disc starts to rotate, and at the same time the ultraviolet light source below is turned on, and the two-axis ultrasonic electric loading unit moves to connect the electric loading device with the polishing pool, and the ultraviolet light source, the electric loading device and the polishing liquid form a photoelectrolytic cell; S4. The ultrasonic transducer and amplitude transformer built into the two-axis ultrasonic electric loading unit come into contact with the polishing disk under the action of ultrasound. The polishing disk combines the photoelectrochemical modification, ultrasound and mechanical friction removal in the photoelectrolysis cell to jointly polish the surface of the diamond substrate.

7. The method according to claim 6, characterized in that The step S1 specifically includes the following steps: The wafer is adsorbed on a conductive metal plate by vacuum, and the back side of the metal plate is connected to the negative pole of the power supply through a conductive pin; The end of the horn is connected to the wafer adsorption ring; The polishing liquid circulation system is started, the polishing liquid is injected into the liquid storage tank, the sensor detects the liquid level of the polishing liquid in real time, and when the polishing liquid soaks the polishing disk, the circulation mode is enabled to maintain the liquid level position.

8. The method according to claim 6, characterized in that In the step S2, when the strong ultraviolet light circumferential irradiation unit is in working state, ultraviolet light with a wavelength less than 200nm can be generated; During the working process, the strong ultraviolet light source is first lowered along the z direction to the surface adjacent to the polishing disc, and then the strong ultraviolet light source is irradiated in a circular trajectory through the freedom of movement in the xy direction, where the movement trajectory is shown in the following formula: Where R1 is the maximum distance that the strong ultraviolet light source moves in the x direction, and R2 is the maximum distance that the strong ultraviolet light source moves in the y direction; The diameter of the circular track is smaller than the radius of the polishing disc, and the polishing disc undergoes surface modification under strong ultraviolet light irradiation.

9. The method according to claim 6, characterized in that In step S3, forming a photoelectrolytic cell comprises the following steps: The ultraviolet light source is activated, and the ultraviolet light is irradiated upward through the waterproof light-transmitting plate. The polishing disc has evenly distributed light-transmitting holes, and the ultraviolet light is irradiated onto the surface of the wafer adsorbed on the ultrasonic electric loading spindle through the light-transmitting holes on the polishing disc; The polishing disk starts rotating motion, and after the motion stabilizes, the two-axis ultrasonic electric loading unit moves so that the ultrasonic electric loading main axis moves down along the z-axis to the surface of the wafer close to the surface of the polishing disk. At this time, the polishing liquid infiltrates the wafer, and the positive electrode of the power supply is connected to the polishing disk through a conductive sheet. The wafer is the cathode and the polishing disk is the anode. The ultraviolet light source, the electric loading device and the polishing liquid form a photoelectrolysis cell, and the wafer surface is oxidatively modified by the strong ultraviolet light.

10. The method according to claim 6, characterized in that The step S4 has the following steps: Under the control of the two-axis motion system, the two-axis ultrasonic electric loading unit descends along the z-axis to the surface of the wafer and contacts the polishing disk. When powered on, the ultrasonic transducer and the amplitude transformer work, and the two-axis ultrasonic electric loading unit vibrates at high frequency along the z-axis direction. The abrasive particles in the polishing liquid continuously impact the surface of the wafer, and the surface of the wafer contacts the polishing disk intermittently at the ultrasonic frequency. The surface of the diamond substrate is polished under the combined action of photoelectrochemical modification, ultrasound and mechanical friction removal.

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