CN117325082A

CN117325082A - Method for manufacturing integrated diamond conditioner of polishing pad

Info

Publication number: CN117325082A
Application number: CN202311521879.XA
Authority: CN
Inventors: 师超钰; 朱建辉; 郭泫洋; 徐钰淳; 赵延军; 邵俊永
Original assignee: Zhengzhou Research Institute for Abrasives and Grinding Co Ltd
Current assignee: Zhengzhou Research Institute for Abrasives and Grinding Co Ltd
Priority date: 2023-11-15
Filing date: 2023-11-15
Publication date: 2024-01-02

Abstract

The invention provides a manufacturing method of an integral diamond trimmer of a polishing pad, which comprises the following steps: s1: processing the disc matrix; s2: growing large-size CVD diamond chips; s3: flattening the two sides of the CVD diamond sheet by using laser to process the large-size CVD diamond sheet; s4: cutting a large-size CVD diamond piece in a customized manner by utilizing laser to obtain a diamond trimming unit; s5: removing the residual graphite layer on the surface of the diamond trimming unit; s6: diamond trimming units which are regularly distributed are fixed on the disc substrate; s7: carrying out precise planarization processing on the working surface of the trimming unit; s8: machining a micro-cone array structure which is regularly arranged on the working surface of the trimming unit; s9: the trimmer index parameter is detected. The integral diamond trimmer manufactured by the method overcomes all the defects and problems of the existing diamond particle trimmer, CVD film-coated trimmer and polycrystalline superhard material trimmer.

Description

Method for manufacturing integrated diamond conditioner of polishing pad

Technical Field

The invention relates to the technical fields of diamond machining and semiconductor polishing, in particular to a manufacturing method of an integral diamond trimmer of a polishing pad.

Background

Chemical Mechanical Polishing (CMP) technology is one of the key processes for surface processing of semiconductor materials, and is widely used in surface planarization processes at various stages in Integrated Circuit (IC) manufacturing processes and surface polishing processes for whole wafers. Chemical mechanical polishing is primarily accomplished by the action of polishing pads, polishing fluids and other chemical agents, which are the primary consumables in the chemical mechanical polishing process, to effect material removal of the surface of a semiconductor wafer substrate.

The polishing pad has the functions of storing and transporting polishing liquid, removing processing scraps, transmitting mechanical load and the like, and the structure and the surface roughness of the polishing pad directly determine the material removal rate and the surface flatness of the semiconductor wafer in the chemical mechanical polishing process. However, after the polishing pad is used for a period of time, abrasive particles in the polishing solution, scraps and byproducts generated in the polishing process can block micropores on the surface of the polishing pad, so that the volume of the micropores is reduced, the number of the micropores is reduced, the surface roughness of the polishing pad is reduced, and a glazed layer with a certain thickness is gradually formed, so that the polishing rate and the polishing quality are reduced, even a wafer is scratched, and the serious consequence of increasing the scrap rate is caused. Therefore, it is necessary to perform proper conditioning (also referred to as "conditioning" or "dressing") of the polishing pad, i.e., the conditioner physically penetrates the porous layer of the conditioning pad surface, removes the passivated glazing layer and plugs within the pores of the polishing pad surface, regenerates the surface to expose new pores, and creates a slightly convex topography on the polishing pad surface, thereby restoring the polishing pad performance. Although no-dressing polishing pads are currently available, a number of technical bottlenecks exist that are difficult to overcome, and cannot be widely used, and most polishing pads need to be dressed in good time.

Dressing of the polishing pad can be performed by both a dresser and a brush. The trimmer grinds and cuts off the surface material of the polishing pad, and increases the surface roughness of the polishing pad, so that the surface glazing layer and the plugs in the micropores are completely removed, but the polishing pad is inevitably worn to a certain extent. Although the brush does not grind and cut off the polishing pad surface material, there is a problem that clogging accumulated in the micropores cannot be removed reliably and the dressing efficiency is extremely low. To meet the high standard processing requirements of semiconductor wafers, most polishing pads are currently dressed by a dressing machine.

Typical pad conditioners are generally diamond particle conditioners, i.e., diamond abrasive particles are regularly fixed to a disc-shaped substrate by electroplating, brazing, sintering, etc. using an orderly arrangement technique. The patent of application number CN202111270275.3 discloses a process for preparing a brazed diamond conditioner based on clustered units, wherein a specific process is adopted to weld each clustered conditioning unit with single diamond abrasive particles at the top end on a conditioner substrate through a brazing process by using a template. However, diamond particle-type trimmers, particularly electroplating-type trimmers, have the risk of degranulation during trimming, which can easily cause serious consequences of damaging the polishing pad and even scratching the semiconductor wafer; although the brazing type and the sintering type have higher holding force on diamond, the high temperature generated in the manufacturing process can damage the strength of the diamond, the diamond is easy to break during the trimming, the fallen diamond fragments can also cause wafer scratch, the high temperature can easily cause matrix deformation, the size and the shape of diamond particles are different, the equal height of the top ends of the diamond particles is poor (the height difference can reach 100 mu m), the number of effective abrasive particles involved in grinding during the trimming is less, the stability of the trimming process is influenced, even the abrasive particles which are excessively high in individual protrusion penetrate into the deep part of a polishing pad, the abrasion of the polishing pad is accelerated, and the wafer polishing yield is reduced; in addition, the metal plating layer, the brazing filler metal and the bonding agent may rub or react with the polishing solution in the finishing process, so that adverse effects are generated on the holding force of diamond abrasive particles, metal pollution is introduced to the IC wafer, and the yield is reduced. Therefore, although diamond particle-type trimmers occupy the mainstream in the current market, difficulties which are difficult to overcome in the aspects of high abrasive particle vertex and the like, threshing, metal pollution, consistency of abrasive particle cutting edges and the like exist, and along with the rapid development of the semiconductor industry, the diamond particle-type trimmers are more and more difficult to adapt to the requirements of cost reduction, synergy and quality improvement.

In recent years, a novel trimmer of CVD coating film type has appeared, that is, a regular rectangular pyramid structure is processed on a substrate by means of forming grinding, etching, laser engraving, etc., and then a diamond film is deposited on the surface of the rectangular pyramid structure. The patent of application number CN201611242132.0 discloses a method and apparatus for manufacturing a polishing pad conditioner, wherein the top of a ceramic ingot is ground to form a regular rectangular pyramid array with an equal-height sharp angle, and the surface of the tip of the ground ceramic ingot is coated with a diamond film, thereby obtaining the polishing pad conditioner. The novel trimmer solves the problems of threshing, metal pollution and inconsistent abrasive particle shapes well, and has obvious advantages compared with a typical traditional trimmer. However, the diamond film is coated on the surface of the pyramid structure of the matrix in a chemical vapor deposition mode, the coating interface has no bonding bond, if the deposited film is too thick, the coating interface is easy to peel off, the pyramid blunt tip is caused, the sharpness of the trimmer is weakened, and meanwhile, the non-uniformity influence of the energy field in the cavity of the deposition equipment causes the non-uniformity of the deposited film thickness of different pyramid surfaces to influence the contour; therefore, the deposited diamond film is generally thinner (about 10-20 μm), but the thinner film inevitably increases the area of the pyramid peak, which has adverse effects on the sharpness and dressing and polishing rate of the dresser, and the fragile film is also easily worn, shortening the service life of the dresser.

In addition, there are very few polycrystalline superhard material-type trimmers, that is, integrated trimmers obtained by machining pyramid shapes on polycrystalline diamond (PCD) or Polycrystalline Cubic Boron Nitride (PCBN) sintered compact by means of electric discharge machining or diamond grinding wheel machining. As in the patent application No. CN201811025287.8, a polishing pad conditioner and a chemical mechanical planarization method are disclosed, in which a non-diamond superhard material PCBN is used as an abrasive material, and individual small pieces with a tapered structure are directly processed and assembled into a CMP polishing pad. The trimmer also solves the problems of threshing, metal pollution and inconsistent abrasive particle shape, and has no problems of film stripping, blunt tip, poor equal height and the like. However, PCD and PCBN contain sintering agents or binders, are heterogeneous, and are easy to generate air holes or pits during electric discharge machining or laser machining, so that not only is the cone structure not ideal in precision, but also the structural strength and wear resistance of the trimmer are reduced, the trimmer is easier to adhere to scraps during trimming of a polishing pad, and the performance of the trimmer is deteriorated, therefore, only a diamond grinding wheel machining mode can be adopted, time and labor are wasted, and the machining cost is too high. Meanwhile, the mechanical property of the polycrystalline superhard material is inferior to that of diamond, the precision and the service life of the trimmer are lower than those of the diamond trimmer, and the overall cost performance of the polycrystalline superhard material trimmer is low.

In view of the above, there is a need to develop an integrated diamond conditioner for polishing pads that overcomes all of the above problems and meets the performance requirements of zero threshing, zero crushing, zero peeling, zero contamination, good shape consistency, good isoheight, high sharpness, high wear resistance, and long service life.

Disclosure of Invention

Aiming at the technical problem that the prior diamond trimmer manufacturing method is difficult to reach the actual requirement, the invention provides a manufacturing method of an integral diamond trimmer of a polishing pad, and the manufactured integral diamond trimmer overcomes the defects and problems of the prior diamond grain trimmer, the CVD film-coated trimmer and the polycrystalline superhard material trimmer and meets the performance requirements of zero threshing, zero crushing, zero stripping, zero pollution, good shape consistency, good isoaltitude, high sharpness, high wear resistance and long service life.

In order to achieve the above purpose, the technical scheme of the invention is realized as follows: a method of manufacturing a unitary diamond conditioner for a polishing pad, comprising the steps of:

s1: processing the disc matrix;

s2: cultivating and growing a whole CVD diamond sheet;

s3: flattening both sides of the CVD diamond piece with a laser, and processing the entire CVD diamond piece;

S4: cutting the whole CVD diamond piece by using laser to obtain a diamond trimming unit;

s5: removing the residual graphite layer on the surface of the diamond trimming unit;

s6: regularly distributed diamond trimming units are fixedly arranged on the disc substrate;

s7: carrying out precise planarization processing on the working surface of the trimming unit;

s8: machining cone array structures with the grain diameters of 100-500 mu m, which are regularly distributed on the working surface of the trimming unit;

s9: and detecting index parameters of the trimmer, and returning to continue processing until the index accuracy is reached if the index requirements are not met.

The specific method for processing the disc substrate in the step S1 is as follows: a disc made of stainless steel is selected as a matrix, and then the disc surface is processed by double-end-face grinding or double-end-face grinding equipment, so that the planeness of two surfaces is not more than 5 mu m, and the parallelism of the two surfaces is less than 5 mu m.

The method for cultivating and growing the whole CVD diamond piece in the step S2 comprises the following steps: placing a silicon substrate in a chemical vapor deposition equipment cavity, introducing a mixed atmosphere of hydrogen and methane into the chemical vapor deposition equipment cavity as a reactant, heating a filament to generate plasma generated by high temperature of 1800-2300 ℃ or direct current arc and microwave, and reacting the gas in the chemical vapor deposition equipment cavity, so that a diamond film is deposited and grown on the surface of the silicon substrate in the chemical vapor deposition equipment cavity, and stripping the diamond self-supporting film from the silicon substrate after deposition and growth are finished, namely the pure CVD diamond sheet.

The method for flattening the two sides of the CVD diamond sheet by laser in the step S3 is as follows:

s31: using an infrared nanosecond laser generator to enable laser to be inclined at a fixed incidence angle of 75 degrees to irradiate the surface of a horizontally placed CVD diamond sheet, adjusting the height of a laser spot emitting head, and enabling the laser to be focused at the highest point area of the surface of the CVD diamond sheet;

s32: adjusting an infrared nanosecond laser generator, under the action of a two-dimensional galvanometer, enabling a laser spot to perform circular motion scanning irradiation along a straight line or an arc line in the horizontal direction, controlling a CVD diamond sheet to perform reciprocating linear motion in the horizontal direction, enabling the reciprocating motion direction to be perpendicular to the laser spot motion scanning direction, and enabling the laser spot to be uniformly distributed on a half area, far away from a laser spot emitting head, of the surface of the CVD diamond sheet through circular motion scanning of the laser spot and reciprocating motion of the CVD diamond sheet;

s33: after one reciprocating rectilinear motion in the horizontal direction is completed, the CVD diamond piece horizontally rotates by an angle θ from its own center until the cumulative rotation is 360 °, θ is 10 ° if the CVD diamond piece is circular in shape, and is 90 ° if the CVD diamond piece is square in shape.

The method for cutting the whole CVD diamond piece by using the laser in the step S4 comprises the following steps:

S41: using an infrared nanosecond laser generator to enable laser to be irradiated on the surfaces of the CVD diamond sheet subjected to flattening processing on the front side and the back side which are vertically and horizontally placed, forming laser spots, adjusting the height of a laser spot emitting head, and enabling the laser to be focused on the upper surface of the horizontally placed CVD diamond sheet;

s42: controlling an infrared nanosecond laser generator, under the action of a two-dimensional galvanometer of the infrared nanosecond laser generator, enabling laser spots to perform cyclic motion scanning irradiation of zigzag multi-section parallel linear tracks in the horizontal direction within the length-width range of a set kerf shape, wherein the kerf width is set to be 200 mu m, and the laser spots are uniformly distributed within the set kerf range for horizontally placing the CVD diamond sheet;

s43: along with the increasing depth of the kerf, the height of a laser spot emitting head of the infrared nanosecond laser generator is adjusted to ensure that laser is always focused on the surface of a material in the kerf, and the height of the laser spot emitting head is fixed and does not change any more until the adjustment height of the laser spot emitting head is accumulated to half of the thickness of the flattened CVD diamond sheet;

s44: laser emitted by an infrared nanosecond laser generator is used for continuously irradiating the kerf region until a straight kerf penetrating through the front surface and the back surface of the CVD diamond sheet is formed;

S45: performing laser cutting on the CVD diamond piece subjected to the flattening processing on the front surface and the back surface according to the set kerf positions to obtain a plurality of CVD diamond pieces, wherein the CVD diamond pieces are used as diamond trimming units, and the diamond trimming units comprise any one or more of the following trimming units: round trimming unit, annular trimming unit, square trimming unit, sector trimming unit, banana trimming unit.

The specific method for removing the residual graphite layer on the surface of the diamond trimming unit in the step S5 is as follows: and etching the residual graphite layers on the flattened surface and the cutting side surface of each diamond trimming unit by adopting atomic hydrogen or atomic oxygen with extremely high reactivity, so as to completely remove graphite components.

The specific method for removing the residual graphite layer on the surface of the diamond trimming unit in the step S5 is as follows: the graphite layer can also be selectively removed by adopting a free abrasive grinding or grinding wheel grinding mode.

The specific method for diamond trimming units distributed on the disc substrate in a fixed and regular manner in the step S6 is as follows: fixing more than one diamond trimming unit on the same disc surface of the disc substrate in an adhesive mode, wherein the flattened surface of the diamond trimming unit is attached to the disc surface of the substrate, and when only a single trimming unit is used, the center of the trimming unit is concentric with the disc substrate; when the trimming units are arranged, the trimming units are distributed on the disc surface of the disc base body in a circular array with central symmetry; when the plurality of trimming units are not in the same shape, the trimming units in different shapes are arranged in a circular array which is symmetrical in the center on the disc surface of the disc substrate in a non-adjacent mode.

The specific method for performing the precise planarization processing on the working surface of the trimming unit in step S7 is as follows:

s71: the disc substrate fixed with the trimming unit is horizontally placed, the back surface of the bonding surface of the trimming unit is a working surface of the trimming unit, the working surface of the trimming unit faces upwards, a picosecond laser generator is adopted, laser beams are vertically irradiated to the working surface of the trimming unit to form laser spots, and the height of a laser spot emitting head is adjusted to enable the laser to be focused at the highest area position of the working surfaces of all the trimming units;

s72: according to the position, the spacing and the shape and the size of each trimming unit, setting a processing pattern consistent with the size, the shape and the distribution of the trimming units, controlling a picosecond laser generator to enable laser spots to sequentially perform zigzag multi-section parallel linear track movement scanning irradiation on the working surface of each trimming unit along the horizontal direction under the action of a two-dimensional vibrating mirror, and enabling the laser spots to be uniformly distributed on the working surfaces of all the trimming units;

s73: and (3) adjusting the height of the laser spot emitting head to ensure that the laser spot is always focused on the highest area of all the working surfaces of the trimming units, repeating the step (S72) until the flatness of the working surfaces of the trimming units is less than 5 mu m and the height difference of the trimming units is less than 5 mu m.

The method for manufacturing a unitary diamond conditioner for polishing pad as set forth in claim 9, wherein the specific method for machining the regular micro-cone array structure on the working surface of the conditioning unit in step S8 is as follows:

s81: the method comprises the steps that a disc substrate with a fixed trimming unit and a working surface subjected to planarization processing is integrally arranged on a positioning fixture, the disc substrate is horizontally placed, and the working surface of the trimming unit faces upwards;

s82: the laser beam is vertically irradiated to the working surface of the trimming unit by adopting an ultrafast pulsed femtosecond laser generator to form a laser spot, and the height of a laser spot emitting head is adjusted to focus the laser on the working surface of the trimming unit;

s83: setting basic processing patterns consistent with the sizes, shapes and distribution of the trimming units according to the positions, the spacing and the shape sizes of each trimming unit, and delineating the working surfaces of all the trimming units as laser irradiation processing areas;

s84: setting more than one structure processing graph for processing the micro cone in the basic processing graph, wherein the shape of the structure processing graph gradually changes from small to large in constant amplitude; the processing patterns of each group of structures are compared, each group of processing patterns comprises circular or polygonal arrays with the same quantity, the same shape, the same central position, the same regular arrangement mode and different sizes, each group of processing areas covers all the trimming units at the same time, and each group of processing areas is sequenced according to the sequence;

S85: the method comprises the steps that a femtosecond laser generator is utilized to enable laser spots to sequentially perform zigzag multi-section parallel linear track movement scanning irradiation on each set of enclosed processing areas along the horizontal direction, so that the laser spots are uniformly distributed in all the enclosed processing areas, and meanwhile, equidistant gradual stepping processing is performed on all the working surfaces of the trimming units from top to bottom, so that trimming units of an integral micro-cone array structure are obtained;

s86: after the steps are completed, the moving scanning direction of the laser light spots is increased by 90 degrees, the scanning direction angles are switched in an accumulated mode, and the steps S82-S85 are repeated until the micro cone array structure on the working face of all the trimming units meets the actual index requirement.

The beneficial effects of the invention are as follows: (1) The invention provides a manufacturing method of an integral diamond trimmer of a polishing pad, which creatively manufactures a novel trimmer different from the existing diamond particle trimmer, CVD film plating trimmer and polycrystalline super-hard material trimmer, overcomes all the defects and problems of threshing, crushing, stripping, pollution, low equal altitude, low service life and the like of the existing trimmer, and achieves excellent service performance.

(2) The integral diamond trimmer comprises integral diamond trimming units with pure components and uniform plastids, does not damage the diamond structure during manufacturing and processing, has excellent physical and mechanical properties and chemical stability, and can meet the use requirements of zero threshing, zero crushing, zero stripping and zero pollution of the trimmer.

(3) The trimming unit and the micro-cone structure of the integral diamond trimmer can achieve extremely high processing precision, have the characteristics of extremely consistent and regular shape, arrangement, height, sharp angle and the like, can realize adjustable and controllable customized and personalized manufacturing, and can meet the use requirements of good height, good shape consistency and high sharpness of convex parts and the like of the trimmer.

(4) The trimming unit of the integral diamond trimmer is made of diamond, has extremely strong wear resistance, can return to processing and repairing after being passivated for repeated use, and can meet the use requirements of high wear resistance and long service life of the trimmer.

(5) Aiming at CVD diamond innovatively, the invention develops complete sets of technologies such as laser planarization processing, laser cutting, laser processing of micro-cone structures and the like, and provides a new thought and a new method for diamond trimmers and other novel diamond tools.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic flow chart of the method of the present invention.

Fig. 2 is a schematic diagram of a laser planarization method according to the present invention.

Fig. 3 is a schematic view showing the effects before and after the laser planarization process of the present invention.

FIG. 4 is a schematic view of the laser spot scanning trajectory in the kerf location and kerf range of the present invention.

Fig. 5 is a schematic diagram of a laser spot scanning trace of the finishing unit precision planarization process of the present invention.

Fig. 6 is a schematic diagram of a scanning track of a laser spot in a first machining region according to the present invention.

FIG. 7 is a schematic view of the laser spot scanning trajectories of the middle set of processing regions of the present invention.

Fig. 8 is a schematic diagram of a scanning track of a laser spot in a final machining area according to the present invention.

Fig. 9 shows a pyramid microstructure machined on a finishing unit according to the present invention.

In the figure, 1 is a whole CVD diamond sheet, 2 is a laser spot emitting head, 3 is a laser spot moving track of double-sided flattening processing, 4 is a laser beam, 5 is a cutting joint and laser spot moving track in the cutting joint, 6 is a diamond trimming unit obtained by cutting, 7 is a disc substrate, 8 is a trimming unit and the laser spot moving track of precise flattening processing thereof, 9 is a laser spot moving track of a first group processing area, 10 is a laser spot moving track of a middle group processing area, and 11 is a laser spot moving track of a last group processing area.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1, a method for manufacturing a unitary diamond conditioner for a polishing pad, comprising the steps of:

s1: a disc made of a corrosion-resistant high-hardness alloy material or a ceramic material is selected as a matrix, and the diameter of the disc is 120mm and the thickness of the disc is 10mm. And then the disc surface is processed by using double-end surface grinding or double-end surface grinding equipment, so that the planeness of both surfaces is not more than 5 mu m, and the parallelism of both surfaces is less than 5 mu m.

S2: cultivating and growing a whole CVD diamond sheet 1, wherein the specific method comprises the following steps:

the mixed atmosphere of hydrogen and methane is introduced into the cavity of the chemical vapor deposition equipment as a reactant, and the reaction gas is activated by using high temperature of 1800-2300 ℃ generated by a heating filament or plasma generated by direct current arc and microwave as an energy mode, so that a vapor phase chemical reaction occurs in the cavity of the equipment, and a diamond film is deposited and grown on the surface of the silicon substrate. Wherein the silicon substrate is circular in shape and has an area not smaller than that of the disk substrate. The thickness of the deposited diamond film is more than 300 mu m, and the difference of deposition rates of different areas can lead to poor surface type precision and large thickness deviation of the deposited diamond film, so that the thickness of the thinnest area of the deposited diamond film is more than 300 mu m. After deposition growth is completed, the silicon substrate is dissolved by strong acid, and the self-supporting diamond film stripped from the substrate is obtained, namely the pure CVD diamond wafer.

S3: the whole CVD diamond piece 1 is processed by flattening both sides of the CVD diamond piece with laser, as shown in fig. 2, specifically by:

s31: the method comprises the steps of utilizing an infrared nanosecond laser generator to enable an emitted laser beam to pass through a beam expander and a reflecting prism, then enabling the emitted laser beam to pass through a two-dimensional galvanometer and a focusing lens and then to be irradiated on the surface of a horizontally placed CVD diamond sheet at a fixed incident angle of 75 degrees, forming a laser spot, adjusting the height of a laser spot emitting head 2, and focusing the laser on the highest point area of the surface of the CVD diamond sheet;

S32: adjusting an infrared nanosecond laser generator, under the action of a two-dimensional galvanometer, enabling a laser spot to perform circular motion scanning irradiation along a straight line or an arc line in the horizontal direction, controlling a CVD diamond sheet to perform reciprocating linear motion in the horizontal direction, enabling the reciprocating motion direction to be perpendicular to the laser spot motion scanning direction, and enabling the laser spot to be uniformly distributed on a half area, far away from the laser spot emitting head 2, of the surface of the CVD diamond sheet through circular motion scanning of the laser spot and reciprocating motion of the CVD diamond sheet;

s33: after one reciprocating linear motion is completed in the horizontal direction, the CVD diamond sheet automatically rotates by an angle of 10 degrees until the cumulative rotation of 360 degrees, so that laser spots are uniformly distributed on the whole upper surface global area of the horizontally placed CVD diamond sheet and only distributed on the upper surface.

The laser light spots are uniformly distributed and irradiated, the laser defocus difference between the high-point area and the low-point area on the surface of the CVD diamond sheet is increased, the high-point defocus is small, the focusing energy is strong, the low-point defocus is large, and the focusing energy is weak, so that the laser energy is automatically distributed on the surface of the CVD diamond sheet, the high-point removal and the low-point removal are realized, and finally the laser planarization processing of the whole global surface of the CVD diamond sheet is realized. The CVD diamond piece is automatically rotated and accumulated for 360 degrees to be processed, the number of times of laser planarization processing can be adjusted according to the real-time surface type result in the processing process of the CVD diamond piece, and the height of the laser spot emitting head 2 is adjusted along with the removal amount of high-point materials on the surface of the CVD diamond piece, so that the laser always keeps the strongest focusing energy in the highest area of the surface of the CVD diamond piece.

And respectively processing the front surface and the back surface of the CVD diamond piece by adopting the same laser planarization processing method until the overall surface global flatness of the two surfaces is less than 10 mu m, and the overall thickness deviation of the CVD diamond piece is less than 5 mu m. A schematic diagram of the effects before and after the laser planarization process is shown in fig. 3.

S4: the whole CVD diamond piece 1 is cut by laser customization to obtain a diamond trimming unit, which comprises the following specific steps:

s41: the laser beam emitted by an infrared nanosecond laser generator is utilized, passes through a beam expander and a reflecting prism, and then is vertically irradiated to the surfaces of the horizontally placed front and back side flattened CVD diamond plates at an incident angle of 0 DEG after passing through a two-dimensional galvanometer and a focusing lens, so as to form laser spots, and the height of a laser spot emitting head 2 is regulated, so that the laser is focused on the upper surface of the horizontally placed CVD diamond plates;

s42: controlling an infrared nanosecond laser generator, under the action of a two-dimensional galvanometer, making laser spots perform cyclic motion scanning irradiation of zigzag multi-section parallel linear tracks along the horizontal direction in the length-width range of a set kerf shape, setting the kerf width to be 200 mu m, and uniformly distributing the laser spots in the set kerf range for horizontally placing the CVD diamond sheet;

S43: along with the increasing depth of the kerf, the height of the laser spot emitting head is adjusted to ensure that the laser is always focused on the surface of the material in the kerf, and the height of the laser spot emitting head 2 is fixed and does not change any more when the adjustment height of the laser spot emitting head is accumulated to half the thickness of the flattened CVD diamond sheet, namely, a focal plane for keeping the laser focusing is positioned at the middle position of the thickness of the CVD diamond sheet;

s44: continuously irradiating the kerf region by using laser emitted by an infrared nanosecond laser generator until forming a straight kerf penetrating through the front surface and the back surface of the CVD diamond sheet;

s45: and carrying out laser cutting on the CVD diamond piece subjected to the flattening processing on the front surface and the back surface according to the set kerf positions to obtain a plurality of CVD diamond pieces, wherein the CVD diamond pieces are used as diamond trimming units, and the diamond trimming units comprise round trimming units and square trimming units.

As shown in fig. 4, the cutting positions of two adjacent diamond trimming units on the CVD diamond sheet should be as close as possible, so as to improve the utilization rate of diamond material, avoid the edge area of the CVD diamond sheet, and eliminate crystal growth or processing defects possibly existing in the edge area. 6 diamond trimming units are cut on one CVD diamond sheet, 3 diamond trimming units are round trimming units, 3 diamond trimming units are square trimming units, and the diameter and the side length are not more than half of the diameter of the disc substrate 7.

S5: the residual graphite layer on the surface of the diamond trimming unit is removed, the infrared nanosecond laser has high power and strong energy, and is suitable for planarization processing and cutting processing for efficiently removing a large amount of materials, but heat can be generated in the diamond processing process to cause diamond graphitization and the residual graphite layer. Specifically, atomic hydrogen or atomic oxygen with extremely high reactivity can be adopted to selectively etch the residual graphite layers on the flattened surface and the cutting side surface of each diamond trimming unit, so that the graphite components are completely removed, and the diamond components are not damaged. The free abrasive grinding or the grinding wheel grinding mode can be selected to selectively remove the graphite layer free abrasive, the fine-grained common abrasive or the super-hard CBN abrasive can be selected, the grinding wheel can be selected to be a fine-grained common abrasive grinding wheel or a super-hard CBN grinding wheel, and the abrasive grain size is generally W40 to be fine.

S6: regularly distributed diamond dressing units are fixed on the disc substrate 7. The diamond trimming units are fixed on the same disc surface of the disc substrate 7 in an adhering mode, the flattened surfaces of the diamond trimming units are attached to the disc surface of the substrate, and the 3 circular trimming units and the 3 square trimming units are regularly and alternately arranged on the disc surface of the disc substrate 7 in a circular array with central symmetry.

S7: the working surface of the trimming unit is precisely flattened, and tiny unevenness introduced when the trimming unit is adhered and fixed is eliminated, and the specific method is as follows:

s71: the disc substrate 7 fixed with the trimming unit is horizontally placed, the back surface of the bonding surface of the trimming unit is the working surface of the trimming unit, the working surface of the trimming unit faces upwards, a picosecond laser generator is adopted to irradiate the working surface of the trimming unit vertically at an incidence angle of 0 DEG to form a laser spot, and the height of the laser spot emitting head 2 is adjusted to enable the laser to be focused at the highest area position of the working surfaces of all the trimming units. The picosecond laser with short wavelength generates little heat during processing, belongs to cold processing, is suitable for precision processing, has small Rayleigh length and short focal depth, and shows obvious focusing energy difference due to small height difference between a high point area and a low point area on a working surface of a trimming unit, and has strong focusing energy in the high point area and weak focusing energy in the low point area, thereby realizing high point more removal and low point less removal.

S72: according to the position, the spacing and the shape and the size of each trimming unit, a processing pattern consistent with the size, the shape and the distribution of the trimming units is set, and the picosecond laser generator is controlled to enable laser spots to sequentially perform zigzag multi-section parallel linear track movement scanning irradiation on the working surface of each trimming unit along the horizontal direction under the action of the two-dimensional galvanometer, the areas outside the working surface of the trimming unit are not irradiated, and the laser spots are uniformly distributed on the working surfaces of all the trimming units.

S73: as shown in fig. 5, the working surfaces of all the trimming units are completely scanned and covered by the laser spots once for one processing pass, the number of processing passes can be adjusted according to the real-time surface shape result in the processing process of the working surfaces of the trimming units, and the height of the laser spot emitting head 2 is adjusted along with the removal amount of the high-point material of the working surfaces of the trimming units, so that the laser always keeps the strongest focusing energy in the highest area of the working surfaces of all the trimming units, and the step S72 is repeated, thereby finally achieving the goal that the working surfaces of all the trimming units are flat and equal in height. The flatness of the working face of each trimming unit is less than 5 mu m; the height difference of all trimming units is less than 5 μm by taking the blank disc surface of the disc substrate 7 as a reference surface.

S8: the method for processing the regular micro-cone array structure on the working surface of the trimming unit comprises the following steps:

s81: the disc base 7 with the finishing unit fixed thereon and the working face subjected to the precision planarization processing is integrally mounted on a precision positioning jig, the disc base 7 is placed horizontally and the working face of the finishing unit is directed upward. The precision positioning fixture is not limited in structure, can adopt claw jogged type, clamping groove jogged type and the like, and ensures repeated positioning precision when the disc substrate 7 is secondarily installed, so that the integral diamond trimmer can be used for processing the working face micro-cone structure again after passivation, and repair and repeated use of the trimmer are realized.

S82: the laser beam emitted by the ultra-fast pulse femtosecond laser generator passes through the beam expander and the reflecting prism, then is perpendicularly irradiated to the working surface of the trimming unit at an incidence angle of 0 DEG after passing through the two-dimensional galvanometer and the focusing lens to form a laser spot, and the height of the laser spot emitting head 2 is adjusted to focus the laser on the working surface of the trimming unit. The working surfaces of the trimming units subjected to precise planarization processing are not only flat but also excellent in contour, and are all positioned on a focal plane after laser focusing.

s86: after the steps are completed, the moving scanning direction of the laser light spots is increased by 90 degrees, the scanning direction angles are switched in an accumulated mode, and the steps S82-S85 are repeated until the micro cone array structure on the working face of all the trimming units meets the actual index requirement. The first group of processing area laser spot scanning tracks are shown in fig. 6, the middle group of processing area laser spot scanning tracks are shown in fig. 7, and the last group of processing area laser spot scanning tracks are shown in fig. 8.

The ultra-fast pulse femtosecond laser processing does not generate heat, and the diamond surface has no damage layer, thereby being suitable for high-precision micro-structure processing. The types of the micro cones are regulated and controlled through the circular or polygonal arrays regularly distributed in the structure processing graph, the circular arrays are processed into conical microstructures without edges, the square arrays are processed into pyramid microstructures with four edges, the triangular arrays are processed into triangular pyramid microstructures with three edges, and the custom micro cone structures corresponding to multiple edges can be customized by other polygonal arrays. As shown in FIG. 9, the top surface size of the micro cone is regulated and controlled through a first group of structure processing patterns with the smallest size, and the side length or the diameter is generally 10-50 μm; setting the bottom surface size of the micro cone through the final group structure processing graph with the largest size, wherein the side length or the diameter is generally 400-800 mu m; the micro cone height is regulated and controlled by the processing times, and is generally 100-300 mu m.

S9: and after finishing the micro-cone array structure processing on all the working surfaces of the trimming units, obtaining the integral diamond trimmer. And observing index parameters such as the height, the top surface size, the bottom surface size, the spacing and the like of each cone on the trimmer by using a laser microscope, evaluating the height consistency, the shape consistency and the arrangement consistency of all cones with the same specification on the trimmer, and if the index requirements are not met, returning to the process for a specific time, and continuing the process until the index precision is reached.

The invention takes the laser processing technology of CVD diamond as the main material, fully considers the extreme equal height, absolute zero threshing and zero pollution, stable and high-efficiency material removal rate and excellent service life of the top end of the convex part on the surface of the trimmer, and aims at carrying out the whole surface flattening processing, the specific shape cutting processing, the regular cone microstructure processing and the like on the whole CVD diamond sheet to manufacture the whole diamond trimmer with a trimming unit which is a single component and uniform mass and made of the whole diamond material, thereby meeting the performance requirements of zero threshing, zero crushing, zero stripping, zero pollution, good shape consistency, good equal height, high sharpness, high wear resistance and long service life.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims

1. A method of manufacturing a unitary diamond conditioner for a polishing pad, comprising the steps of:

s1: processing the disc substrate (7);

s2: cultivating and growing a whole CVD diamond piece (1);

s3: flattening both sides of the CVD diamond piece by using laser, and processing the whole piece of CVD diamond piece (1);

s4: cutting the whole CVD diamond piece (1) by using laser to obtain a diamond trimming unit;

s6: regularly distributed diamond trimming units are fixedly arranged on the disc substrate (7);

2. The method for manufacturing a unitary diamond conditioner for polishing pad according to claim 1, wherein the specific method for processing the disc substrate (7) in step S1 is as follows: a disc made of stainless steel is selected as a matrix, and then the disc surface is processed by double-end-face grinding or double-end-face grinding equipment, so that the planeness of two surfaces is not more than 5 mu m, and the parallelism of the two surfaces is less than 5 mu m.

3. The method of manufacturing a monolithic diamond conditioner for polishing pad according to claim 2, wherein the method of growing a monolithic CVD diamond piece (1) in step S2 is: placing a silicon substrate in a chemical vapor deposition equipment cavity, introducing a mixed atmosphere of hydrogen and methane into the chemical vapor deposition equipment cavity as a reactant, heating a filament to generate plasma generated by high temperature of 1800-2300 ℃ or direct current arc and microwave, and reacting the gas in the chemical vapor deposition equipment cavity, so that a diamond film is deposited and grown on the surface of the silicon substrate in the chemical vapor deposition equipment cavity, and stripping the diamond self-supporting film from the silicon substrate after deposition and growth are finished, namely the pure CVD diamond sheet.

4. The method for manufacturing a monolithic diamond conditioner for a polishing pad according to claim 3, wherein the method for planarizing both sides of the CVD diamond piece using a laser in step S3 is:

s31: using an infrared nanosecond laser generator to enable laser to be inclined at a fixed incidence angle of 75 degrees to irradiate the surface of a horizontally placed CVD diamond sheet, adjusting the height of a laser spot emitting head (2) and enabling the laser to be focused at the highest point area of the surface of the CVD diamond sheet;

S32: adjusting an infrared nanosecond laser generator, under the action of a two-dimensional galvanometer, enabling a laser spot to perform circular motion scanning irradiation along a straight line or an arc line in the horizontal direction, controlling a CVD diamond sheet to perform reciprocating linear motion in the horizontal direction, enabling the reciprocating motion direction to be perpendicular to the laser spot motion scanning direction, and enabling the laser spot to be uniformly distributed on a half area, far away from a laser spot emitting head (2), of the surface of the CVD diamond sheet through circular motion scanning of the laser spot and reciprocating motion of the CVD diamond sheet;

5. A method of manufacturing a monolithic diamond conditioner for polishing pad according to any one of claims 2 to 4, wherein the method of cutting the monolithic CVD diamond piece (1) with laser light in step S4 is:

s41: using an infrared nanosecond laser generator to enable laser to be irradiated on the surfaces of the CVD diamond sheet subjected to flattening processing on the front side and the back side which are vertically and horizontally placed, forming laser spots, and adjusting the height of a laser spot emitting head (2) to enable the laser to be focused on the upper surface of the horizontally placed CVD diamond sheet;

s43: along with the increasing depth of the kerf, the height of a laser spot emitting head of the infrared nanosecond laser generator is adjusted to ensure that laser is always focused on the surface of a material in the kerf, and the height of the laser spot emitting head (2) is fixed and does not change any more when the adjustment height of the laser spot emitting head is accumulated to half the thickness of the flattened CVD diamond sheet;

6. The method for manufacturing a unitary diamond conditioner for a polishing pad according to claim 5, wherein the specific method for removing the residual graphite layer on the surface of the diamond conditioning unit in step S5 is as follows: and etching the residual graphite layers on the flattened surface and the cutting side surface of each diamond trimming unit by adopting atomic hydrogen or atomic oxygen with extremely high reactivity, so as to completely remove graphite components.

7. The method for manufacturing a unitary diamond conditioner for a polishing pad according to claim 5, wherein the specific method for removing the residual graphite layer on the surface of the diamond conditioning unit in step S5 is as follows: the graphite layer can also be selectively removed by adopting a free abrasive grinding or grinding wheel grinding mode.

8. The method for manufacturing a monolithic diamond conditioner for polishing pad according to claim 6 or 7, wherein the specific method for forming diamond conditioning units on the disc substrate (7) in a fixed regular distribution in step S6 is as follows: fixing more than one diamond trimming unit on the same disc surface of a disc substrate (7) in an adhesive mode, wherein the flattened surface of the diamond trimming unit is attached to the disc surface of the substrate, and when only a single trimming unit is used, the center of the trimming unit is concentric with the disc substrate; when the trimming units are arranged, the trimming units are distributed on the disc surface of the disc base body in a circular array with central symmetry; when the plurality of trimming units are not in the same shape, the trimming units in different shapes are arranged in a circular array which is symmetrical in the center on the disc surface of the disc substrate in a non-adjacent mode.

9. The method for manufacturing a unitary diamond conditioner for polishing pad as set forth in claim 8, wherein the specific method for performing the precision planarization process on the working surface of the conditioning unit in step S7 is as follows:

s71: the disc substrate (7) fixed with the trimming unit is horizontally placed, the back surface of the bonding surface of the trimming unit is a working surface of the trimming unit, the working surface of the trimming unit faces upwards, a picosecond laser generator is adopted, a laser beam is vertically irradiated to the working surface of the trimming unit to form a laser spot, and the height of a laser spot emitting head (2) is adjusted to enable the laser to be focused at the highest area position of the working surfaces of all the trimming units;

10. The method for manufacturing a unitary diamond conditioner for polishing pad as set forth in claim 9, wherein the specific method for machining the regular micro-cone array structure on the working surface of the conditioning unit in step S8 is as follows:

s81: the disc substrate (7) with the fixed trimming unit and the working surface subjected to planarization processing is integrally arranged on a positioning fixture, the disc substrate (7) is horizontally arranged, and the working surface of the trimming unit faces upwards;

s82: the laser beam is vertically irradiated to the working surface of the trimming unit by adopting an ultrafast pulse femtosecond laser generator to form a laser spot, and the height of a laser spot emitting head (2) is adjusted to focus the laser on the working surface of the trimming unit;