CN113290501A

CN113290501A - Diamond wafer composite polishing processing method and device

Info

Publication number: CN113290501A
Application number: CN202110662117.6A
Authority: CN
Inventors: 路家斌; 王新汉; 熊强; 邓家云; 阎秋生; 刘文涛
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2021-06-15
Filing date: 2021-06-15
Publication date: 2021-08-24

Abstract

The invention relates to the technical field of chemical mechanical polishing processing, and discloses a composite polishing processing method of a diamond wafer, which comprises the following steps: the method comprises the following steps: preparing a Fenton reaction solution and a photocatalytic reaction solution; step two: irradiating the prepared Fenton reaction solution and photocatalytic reaction solution in the first step by adopting ultraviolet light; step three: mounting the diamond workpiece on a workpiece disc of a polishing device, enabling a polishing pad of the polishing device to be in contact with the diamond workpiece, and then conveying the Fenton reaction liquid and the photocatalytic reaction liquid subjected to ultraviolet irradiation in the second step onto the polishing pad; step four: the polishing pad and the diamond do relative rotation motion to polish, and a large amount of hydroxyl free radicals OH generated in the step two accelerate the removal of the abrasive particles to the surface material of the workpiece in the polishing process, so that the polishing efficiency of the diamond wafer can be effectively improved, and the surface quality can be improved. The invention also provides a polishing device for realizing the method.

Description

Diamond wafer composite polishing processing method and device

Technical Field

The invention relates to the technical field of chemical mechanical polishing, in particular to a composite polishing method and a composite polishing device for a diamond wafer.

Background

The development of semiconductor material technology has gone through the silicon, gallium arsenide, silicon carbide and gallium nitride third generation material systems, and is currently in the development stage of the third generation materials. The monocrystalline diamond is the development direction of upgrading and updating in the technical field of semiconductors, and is a strategic electronic information material for supporting the industrial upgrading with intellectualization as a characteristic and the development of high and new technology industries in the future. The monocrystalline diamond has good mechanical properties, extremely low friction coefficient (0.08-0.1), highest natural hardness (100GPa), good wear resistance, good chemical stability, high thermal conductivity (2 x 103W/(mK)), large resistance (1013 omega-cm), high transmittance and the like. The diamond not only has extremely low dielectric constant, but also has high forbidden bandwidth, carrier mobility, thermal conductivity and breakdown voltage, and the diamond can be semiconductorized by doping a proper amount of boron atoms, so that the diamond becomes an excellent semiconductor material, for example, the diamond semiconductor can work at a high temperature of 600 ℃, the working frequency can reach 81GHz, the diamond can be applied to the fields of microwave, millimeter wave band ultra-high-speed computer chips and the like, and the diamond is considered as an ideal semiconductor substrate material in the future.

Although diamond has excellent properties, diamond has characteristics of high hardness, high brittleness, high chemical stability and the like, so that diamond is a material which is extremely difficult to process. The anisotropy of single crystal diamond results in large differences in material removal and surface quality when polished in different directions. The traditional mechanical polishing has low processing efficiency and is easy to generate processing damage, the surface damage and the sub-surface damage of a diamond workpiece can be caused, and the mechanical impact in the polishing process can cause the formation of pits, sub-surface cracks and lattice damage on the polishing surface. The chemical mechanical polishing is widely and mature in semiconductor materials such as monocrystalline silicon and the like, so that the chemical mechanical polishing has a certain reference function in processing of the diamond. The chemical mechanical polishing method is a processing method of ultra-precision polishing, and utilizes an oxidizing agent to increase the polishing rate.

Chinese patent application CN112809458A (published as 2021, 05 and 18) discloses a silicon carbide wafer and a processing method thereof, wherein the processing method of the silicon carbide wafer comprises: carrying out double-sided coarse grinding on the cleaned and classified silicon carbide wafers; carrying out double-sided finish grinding on the silicon carbide wafer subjected to double-sided coarse grinding; carrying out catalyst-assisted chemical mechanical polishing on the silicon carbide wafer subjected to double-sided fine grinding; the polishing solution is an acidic colloid formed by first grinding particles, a first dispersing agent, an oxidant, a catalyst, a pH regulator and deionized water; the mass ratio of the grinding particles to the dispersing agent to the oxidizing agent to the catalyst to the pH regulator to the deionized water is 5-15; 2-5; 10-20; 3-5; 5-10; 45-75. The chemical mechanical polishing adopts the polishing solution which is an acidic colloid formed by adopting first grinding particles, first dispersing agent, oxidant, catalyst, pH regulator and deionized water, the catalyst is at least one of ferric oxide, ferroferric oxide and ferrous oxide, the surface of the silicon carbide wafer is oxidized by Fenton reaction, and the reagent is Fe²⁺And H₂O₂In combination of (1) in Fe²⁺Under the catalytic action of (A), H₂O₂The decomposition activation energy is low, a large amount of intermediate active species hydroxyl radicals OH are generated, and then the surface of the silicon carbide wafer is oxidized to generate a silicon oxide soft layer, so that the mechanical erosion of grinding particles is facilitated. However, the hardness of diamond is higher than that of silicon carbide, and the hydroxyl radical OH generated in the conventional fenton reaction solution is limited, so that the oxidation effect on the surface of the diamond wafer is limited, and the polishing efficiency is still low.

Disclosure of Invention

The invention aims to provide a diamond wafer composite polishing processing method and a diamond wafer composite polishing processing device for accelerating the removal of abrasive particles to the surface material of a workpiece in the polishing processing process.

In order to achieve the above object, the present invention provides a diamond wafer composite polishing method, comprising the steps of:

the method comprises the following steps: preparing a Fenton reaction solution;

step two: irradiating the prepared Fenton reaction solution in the first step by adopting ultraviolet light;

step three: mounting the diamond workpiece on a workpiece disc of a polishing device, enabling a polishing pad of the polishing device to be in contact with the diamond workpiece, and then conveying the Fenton reaction liquid subjected to ultraviolet irradiation in the second step onto the polishing pad;

step four: the polishing pad and the diamond are polished by relative rotation motion.

Preferably, in the step one, a photocatalytic reaction solution is further prepared; in the second step, ultraviolet light is adopted to irradiate the prepared Fenton reaction solution and photocatalytic reaction solution in the first step; (ii) a In the third step, the Fenton reaction solution and the photocatalytic reaction are both delivered to the polishing pad.

Preferably, the Fenton reaction solution is composed of a first base solution, first abrasive grains, a Fenton reaction catalyst, and H₂O₂And deionized water.

Preferably, the photocatalytic reaction solution is formed by mixing a second base solution, second abrasive particles, a photocatalyst, an electron capture agent, and a pH adjuster.

Preferably, in the second step, the illumination intensity of the ultraviolet light can be selected to be 500mW/cm²-1500mW/cm²。

The invention also provides a diamond wafer composite polishing processing device, comprising:

the workpiece disc moving assembly is used for loading a workpiece and driving the workpiece to rotate;

a polishing disk motion assembly comprising a polishing pad and a polishing disk, the polishing pad carried on the polishing disk;

the polishing solution supply system comprises a polishing solution preparation device and a conveying device for conveying the liquid in the polishing solution preparation device to the polishing disc;

and the ultraviolet light generating device is used for generating ultraviolet light and irradiating the ultraviolet light on the polishing solution preparation device.

Preferably, the workpiece disk motion assembly comprises a workpiece disk, a connecting flange, a workpiece disk drive spindle, a workpiece disk driver and a deflection mechanism, wherein the workpiece disk is used for loading a workpiece, the workpiece disk is connected with the workpiece disk drive spindle through the connecting flange, and the workpiece disk driver is connected with the workpiece disk drive spindle to drive the workpiece disk drive spindle to rotate;

the deflection mechanism comprises a deflection swing rod and a deflection sliding block, the deflection swing rod is parallel to the polishing disk, the workpiece disk driver is connected to the deflection sliding block, and the deflection sliding block is movably connected to the deflection swing rod.

Preferably, the workpiece disk motion assembly further comprises a pressure cylinder, the pressure cylinder is connected to the deflection slider, and the workpiece disk driver is connected to an output end of the pressure cylinder.

Preferably, the polishing solution supply system further comprises a stirrer, and the stirrer is arranged on the polishing solution preparation device.

Preferably, the ultraviolet light generating device comprises an ultraviolet light generator, an optical fiber, an ultraviolet light emitting head and a bracket, wherein the ultraviolet light generator is used for generating ultraviolet light, the ultraviolet light generator is connected with the ultraviolet light emitting head through the optical fiber, the ultraviolet light emitting head is provided with a fly eye lens, and the ultraviolet light emitting head can be movably connected to the bracket along a direction close to or far away from the container.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, the Fenton reaction liquid is irradiated by ultraviolet light, so that H can be accelerated under the irradiation of the ultraviolet light₂O₂The decomposition of the solution generates extra hydroxyl free radical OH, and the concentration of the hydroxyl free radical OH of the Fenton reaction system is increased; on the other hand, accelerate Fe³⁺Reduction to Fe²⁺The speed of (3) promotes the progress of the Fenton reaction, generates more hydroxyl radicals OH, and increases Fe in the Fenton reaction²⁺And Fe³⁺At a rate such that, when polished, the same amount is usedThe lower hydroxyl free radical OH has higher hydroxyl free radical OH to carry out oxidation reaction with the workpiece, thereby quickening the removal of the surface material of the workpiece by abrasive particles in the polishing process, effectively improving the polishing efficiency of the diamond wafer and improving the surface quality.

Drawings

Fig. 1 is a flowchart of a diamond wafer composite polishing method according to a first embodiment of the present invention.

FIG. 2 is a graph showing a comparison of OH formation concentrations in a light-irradiated Fenton reaction solution and a non-light-irradiated Fenton reaction solution according to a first embodiment of the present invention.

Fig. 3 is a flowchart of a diamond wafer composite polishing method according to a second embodiment of the present invention.

FIG. 4 is a comparison graph of OH formation concentrations in a Fenton reaction solution and a photocatalyst under light irradiation and in a Fenton reaction solution and a photocatalyst under no light irradiation in example two of the present invention.

FIG. 5 is H₂O₂Illumination (UV) + H₂O₂Fenton (Fenton), light (UV) + Fenton (Fenton), TiO₂+H₂O₂Illumination (UV) + TiO₂+H₂O₂、TiO₂+ Fenton (Fenton), light (UV) + TiO₂+ Fenton (Fenton) eight solutions-OH solubility as a function of reaction time.

FIG. 6 shows illumination + TiO₂+H₂O₂Total iron ion, Fe, of the solution²⁺Total iron ion and Fe of ion and Fenton reaction solution²⁺Graph of ion change with reaction time.

FIG. 7 shows a schematic representation of the case of H₂O₂Illumination (UV) + H₂O₂Fenton (Fenton), light (UV) + Fenton (Fenton), TiO₂+H₂O₂Illumination (UV) + TiO₂+H₂O₂、TiO₂+ Fenton (Fenton), light (UV) + TiO₂And a graph of material removal rates when eight solutions of + Fenton (Fenton) were used as polishing solutions.

FIG. 8 shows a schematic representation of the case of H₂O₂Illumination (UV) + H₂O₂Fenton (Fenton), light (UV) + Fenton (Fenton), TiO₂+H₂O₂Illumination (UV) + TiO₂+H₂O₂、TiO₂+ Fenton (Fenton), light (UV) + TiO₂+ Fenton (Fenton) eight solutions as polishing solutions.

Fig. 9 is a schematic structural view of a diamond wafer composite polishing apparatus according to a third embodiment of the present invention.

In the figure, 100-workpiece;

200-a frame;

300-an ultraviolet light generating device; 310-ultraviolet generator, 320-optical fiber; 330-ultraviolet light emitting head; 340-a bracket;

400-workpiece disk motion assembly; 410-yaw drive; 420-a deflection swing rod; 430-a yaw slider; 440-a pressure cylinder; 450-a workpiece disk drive; 460-a workpiece disk drive spindle; 470-connecting flange; 480-a workpiece tray;

500-a polishing disc motion assembly; 510-a polishing pad; 520-a polishing disk; 530-polishing disk drive spindle; 540-polishing disk drive spindle pulley; 550-a belt; 560-polishing disk drive pulley; 570-polishing disk drive;

600-a polishing liquid supply system; 610-polishing solution preparation device; 611-a photocatalytic reaction vessel; 612-photocatalytic reaction liquid; 613-Fenton reaction vessel; 614-Fenton reaction liquid; 620-stirrer; 630-a peristaltic pump; 640-a liquid conduit;

700-control panel.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example one

As shown in fig. 1, a diamond wafer composite polishing method according to a preferred embodiment of the present invention includes the steps of:

the method comprises the following steps: preparing a Fenton reaction solution;

The fenton reaction is a reaction system in which hydrogen peroxide is combined with ferrous ions to form a compound having a strong oxidizing property. Hydrogen peroxide, under the action of a ferrous salt catalyst, generates hydroxyl radicals (OH) which have a higher oxidizing electrode potential (E2.8V) than other oxidizing agents, second only to fluorine (E2.87V) among the common oxidizing agents. The chemical reaction process is as follows:

Fe²⁺+H₂O₂→Fe³⁺+OH^-+·OH

3C+4·OH+O₂→2CO↑+2H₂O+CO₂↑

Fe³⁺+H₂O₂→Fe²⁺+H⁺+·OOH

in this example, after the irradiation of ultraviolet light, the reaction process is as follows:

H₂O₂+hv→2·OH

Fe²⁺+H₂O₂→Fe³⁺+OH^-+·OH

Fe³⁺+H₂O₂→Fe(OH)²⁺+H⁺

Fe(OH)²⁺+hv→Fe²⁺+·OH

Fe³⁺+H₂O₂+hv→Fe²⁺+H⁺+·OH

Fe³⁺+H₂O₂→Fe²⁺+HO₂·+H⁺

therefore, in this example, the Fenton reaction solution is irradiated with ultraviolet light, so that the irradiation of ultraviolet light can accelerate H₂O₂The decomposition of the solution generates additional hydroxyl free radical OH, increases the concentration of the hydroxyl free radical OH in the Fenton reaction system, and accelerates the Fe³⁺Reduction to Fe²⁺The speed of (3) promotes the progress of the Fenton reaction, generates more hydroxyl radicals OH, and increases Fe in the Fenton reaction²⁺And Fe³⁺The conversion rate between the two is high, and more hydroxyl radicals OH are generated, so that the hydroxyl radicals OH with higher concentration are subjected to oxidation reaction with a workpiece under the same dosage during polishing, the hardness of the surface of the workpiece is reduced, the hydroxyl radicals OH are easier to remove when being rubbed by a polishing pad, the removal of abrasive particles to the surface material of the workpiece during polishing is accelerated, the polishing efficiency of the diamond wafer can be effectively improved, and the surface quality is improved.

In this example, methyl orange solutions were added to the non-irradiated fenton reaction solution and the irradiated fenton reaction solution, respectively, and it was confirmed that the transmittance of the methyl orange solution in the irradiated fenton reaction solution rose rapidly. Further, the OH formation concentrations of the Fenton reaction solution without irradiation of light and the Fenton reaction solution with irradiation of light were compared, as shown in FIG. 2. Therefore, OH generated from the fenton reaction solution subjected to light irradiation is more than that generated from the fenton reaction solution not subjected to light irradiation, and the material removal rate and polishing efficiency of polishing of the diamond wafer can be improved.

In this example, the Fenton reaction solution was composed of the first base solution, the first abrasive, the Fenton reaction catalyst, and H₂O₂And deionized water. Optionally, deionized water can be used as the first base liquid, and solvents such as silicone oil and mineral oil can also be used as the base liquid; the first abrasive particles are abrasive materials with the particle size of 1-5 mu m, and the abrasive materials can be diamond, silicon carbide, alumina, silicon dioxide, cerium oxide and other materials; the Fenton reaction catalyst adopts a reagent with the particle size of 1-5 mu m, and Fe can be selected₃O₄Catalysts such as FeO and the like which can ionize a large amount of ferrous ions can also be selected to replace ferrous salts with iron-containing catalysts or ferric ion-containing catalysts to form Fenton-like reaction, the Fenton-like catalysts can microelectrolyze the ferrous ions, and hydrogen peroxide can generate hydroxyl radicals (. OH) under the action of the ferrous ions of the catalysts. In this embodiment, the abrasive concentration is 10 wt%, H₂O₂5 wt% concentration of Fe₃O₄The concentration was 2 wt%.

The photocatalytic reaction solution of the present embodiment is formed by mixing the second base solution, the second abrasive, the photocatalyst, the electron capture agent, and the pH adjuster. Optionally, the second abrasive particles adopt abrasives with the particle size of 1-5 μm; the photocatalyst is prepared from 10-100 nm particle size reagent such as TiO₂Materials such as zinc oxide and cerium oxide; hydrochloric acid and sodium hydroxide are used as pH regulators. The electron scavenger is used to trap a free electron excited to transition to the conduction band in the photocatalytic reaction, and promote the generation of OH. In this example, the abrasive concentration was 10 wt%, H₂O₂TiO 5 wt% concentration₂The concentration was 4 g/L. In addition, under acidic conditions H₂O₂The solution is more stable, and the photocatalysis effect is better. The pH value is generally 2-5, and the best effect is 3.

And in the second step, starting the ultraviolet light generating device, setting the wavelength and the illumination intensity of ultraviolet light according to a preset value, guiding the ultraviolet light into the ultraviolet light emitting head through the optical fiber, and then emitting the ultraviolet light through the fly eye lens in the ultraviolet light emitting head to form ultraviolet light spots. The position of the ultraviolet light emitting head was adjusted so that a spot of ultraviolet light was irradiated on the Fenton reaction solution to generate a large amount (. OH). Can be with ultraviolet irradiation on the liquid level of the container that holds fenton reaction liquid through ultraviolet light emission head, also direct irradiation is watered on the polishing pad that drenches by fenton reaction liquid to the product after the reaction can directly take place the oxidation to diamond workpiece. In this embodiment, the Fenton reaction solution is delivered to the polishing pad, and the polishing solution can be uniformly dispersed on the surface of the workpiece by the dispersion action of the polishing pad.

In the second step, the illumination intensity of the ultraviolet light can be selected to be 500mW/cm²-1500 mW/cm². In addition, in the polishing parameters, the polishing pressure can be 0.01MPa-0.05MPa, when the polishing pressure is too small, the cutting depth of the abrasive to the surface of the wafer is too small, the removal rate of diamond workpiece materials is small, and the polishing efficiency is low; excessive polishing pressure can cause the surface quality of the diamond workpiece to be reduced and even cause the workpiece to be broken. The polishing pad is used mainly for dispersing a polishing liquid over the surface of a workpiece and removing reaction products after polishing. In addition, in order to reduce the damage of the surface in the polishing process, a felt pad can be selected as the polishing pad, and the felt pad can better absorb the polishing solution and provide a faster polishing solution updating rate. In addition, the rotation speed of the workpiece disc and the polishing pad can be set to be 40rpm-80rpm, the rotation speed of the workpiece disc and the polishing pad has an influence on the surface quality of the diamond workpiece, and the polishing quality is deteriorated if the rotation speed is too large or too small.

Example two

As shown in fig. 3, the present embodiment is different from the first embodiment in that, in the first step, a photocatalytic reaction solution is further disposed; in the second step, ultraviolet light is adopted to irradiate the prepared Fenton reaction solution and photocatalytic reaction solution in the first step; in the third step, the Fenton reaction solution and the photocatalytic reaction solution are both delivered to the polishing pad. Therefore, the polishing solution of this example uses both the fenton reaction solution and the photocatalytic reaction solution, and both are irradiated with the ultraviolet light.

In this embodiment, because the rates of generating hydroxyl radicals by the fenton reaction and the photocatalytic reaction are very fast, the fenton reaction solution and the photocatalytic reaction solution can be respectively conveyed to the polishing pad first, and then the polishing pad is irradiated by the ultraviolet light, so that the fenton reaction solution and the photocatalytic reaction solution on the polishing pad are irradiated by the ultraviolet light to react. In addition, it should be noted that the fenton reaction solution and the photocatalytic reaction solution can be respectively irradiated by ultraviolet light and then mixed to form a mixed solution to be delivered to the polishing pad; or, the Fenton reaction solution and the photocatalytic reaction solution are mixed firstly, and then are conveyed to the polishing pad after being irradiated by ultraviolet light.

The photocatalytic reaction refers to nano TiO₂After the particle is irradiated by ultraviolet light with the wavelength of less than 387.5nm, electrons in the valence band are excited to jump to the conduction band to form free electrons, and simultaneously positive holes are formed in the valence band, and the positive holes can be adsorbed on TiO₂H of the particle surface₂O₂Molecule and hydroxide ion (OH)^-) Oxidation reaction occurs to generate hydroxyl radical (. OH) with strong oxidizing property, the oxidation-reduction potential is (2.76eV), and free electrons can be reacted with H₂O₂、O₂Equimolecular reaction to generate OH and oxygen free radical O₂(redox potential 2.07 eV). The photocatalytic reaction process is as follows:

TiO₂+hv→h⁺+e^-

H₂O₂+e^-→2·OH

h⁺+H₂O→H⁺+·OH

H₂O₂+hv→H₂O+O₂

e^-+O₂→·O₂

H₂O₂+·O₂→H⁺+·OH+O₂

in this embodiment, the photocatalytic reaction solution and the fenton reagent are mixed to be used as the polishing solution, and the reaction process is as follows:

TiO₂+hv→e^－+h⁺

Fe³⁺+e^－→Fe²⁺

h⁺+H₂O→H⁺+·OH

Fe²⁺+H₂O₂→Fe³⁺+OH^-+·OH

H⁺+OH^-→H₂O

the reaction principle is illumination TiO₂The photocatalyst excites a large amount of e^－And Fe which is a product of the Fenton reaction³⁺Generation of Fe after obtaining electrons²⁺Further promote the Fenton reaction, and positively charge the hole h⁺Can generate a large amount of H by reacting with water⁺And OH, and H⁺Can also react with the product OH of Fenton reaction^-Reaction to form H₂And O. The progress of the above reaction can also promote the progress of the photocatalytic reaction according to the principle of chemical equilibrium shift. Therefore, the concentration of OH generated from the mixed solution is much higher than the sum of the photocatalytic reaction alone and the Fenton reaction alone, as shown in FIG. 4.

The faster the hydroxyl radical generation rate, the higher the OH concentration in the solution, so that the higher the oxidation of the reaction solution, the higher the oxidation-reduction potential ORP value. By measuring the. OH concentrations of the eight solutions, the experimental results shown in FIG. 5 were obtained. In FIG. 5, line a is the. OH solubility in H2O2 solution; line b is illumination (UV) + H₂O₂I.e. by UV irradiation H₂O₂OH solubility in solution; the c line is Fenton (Fenton), namely the OH solubility of the Fenton reaction solution without light irradiation; d line is illumination (UV) + Fenton (Fenton), namely the OH solubility of Fenton reaction solution subjected to illumination; e line is TiO₂+H₂O₂I.e. TiO without being illuminated₂And H₂O₂OH solubility of the mixed solution of (1); the f line is illumination (UV) + TiO₂+H₂O₂I.e. irradiated TiO₂And H₂O₂OH solubility of the mixed solution of (1); g line is TiO₂+ Fenton (Fenton), i.e. TiO without being illuminated₂OH solubility of a mixed solution of the solution and the fenton reaction solution; h lineIs illumination (UV) + TiO₂+ Fenton (Fenton), i.e. TiO illuminated₂OH solubility of the solution and the Fenton reaction solution. As can be seen in FIG. 5, the illumination (UV) + TiO of this example₂The + Fenton (Fenton) has the highest redox potential rise rate and the highest potential, so the OH concentration in the solution is the highest.

In addition, light (UV) + TiO₂+ Fenton (Fenton) solution, Fenton (Fenton) reaction solution and illumination (UV) + TiO₂+H₂O₂Adding the three solutions into methyl orange solution respectively, and after 30 minutes, irradiating by light (UV) + TiO₂The transmittance of the + Fenton (Fenton) solution was 5 times that of the Fenton (Fenton) reaction solution, and the light (UV) + TiO was irradiated₂+H₂O₂1.38 times of the solution, and the OH solubility is 11.4 percent higher than that of the two. On the basis of independent action of ultraviolet light and Fenton reaction, the ultraviolet light and the Fenton reaction are compounded, the reaction rate is not only simple superposition of the ultraviolet light and the Fenton reaction, and the ultraviolet light catalysis can also promote Fe in the Fenton reaction process³⁺To Fe²⁺Further increasing the chemical reaction rate and increasing the concentration of hydroxyl radicals in the solution.

And, after irradiating with light + TiO₂+H₂O₂Total iron ion, Fe of solution and Fenton reaction solution²⁺The ions were measured and the results shown in fig. 6 were obtained. Thus, Fenton and UV + TiO were in the same time₂The total iron ions of the + Fenton reaction system are almost the same, indicating that Fe is present under both conditions₃O₄Has the same dissolution ionization speed, namely the Fe ionized in the same time²⁺And Fe³⁺The total amount of (a) is the same. After the Fenton composite photocatalysis, the ferrous ions in each time period in the reaction process are increased by 15-25%, which shows that the ultraviolet photocatalysis can promote Fe in the Fenton reaction process³⁺To Fe²⁺Thereby increasing the rate of formation of hydroxyl radicals.

Will adopt H₂O₂Illumination (UV) + H₂O₂Fenton (Fenton), light (UV) + Fenton (Fenton), TiO₂+H₂O₂Illumination (UV) + TiO₂+H₂O₂、TiO₂+ Fenton (Fenton), light (UV) + TiO₂The eight solutions of + Fenton (Fenton) were used as polishing solutions to process the workpiece, and the material removal rate of the workpiece was as shown in fig. 7, and the surface roughness of the workpiece was as shown in fig. 8. It is understood that the polishing effect of the present embodiment using the mixed solution of the ultraviolet light irradiation fenton reaction solution and the photocatalytic reaction solution as the polishing solution is the best.

Other steps in this embodiment are the same as those in the first embodiment, and are not described herein again.

EXAMPLE III

As shown in fig. 9, the present embodiment also provides a diamond wafer composite polishing apparatus including:

the workpiece tray moving assembly 400, the workpiece tray moving assembly 400 is used for loading the workpiece 100 and driving the workpiece 100 to rotate; a polishing disk motion assembly 500, the polishing disk assembly 500 including a polishing pad 510 and a polishing disk 520, the polishing pad 510 rotatably coupled to the polishing disk 520; the polishing solution supply system 600, the polishing solution supply system 600 includes a polishing solution preparation device 610 and a delivery device for delivering the liquid in the polishing solution preparation device 610 to the polishing disk 520; the ultraviolet light generating device 300, the ultraviolet light generating device 300 is used for generating ultraviolet light and irradiating on the polishing solution preparation device 610. According to the embodiment, the polishing solution preparation device 610 is used for preparing the Fenton reaction solution, the ultraviolet light generating device 300 is used for generating ultraviolet light to irradiate the Fenton reaction solution, so that the Fenton reaction solution generates a large amount of hydroxyl radicals OH to perform oxidation reaction with a workpiece, the removal of the surface material of the workpiece by abrasive particles in the polishing process is accelerated, the polishing efficiency of the diamond wafer can be effectively improved, and the surface quality is improved. The workpiece tray motion assembly 400, the polishing tray motion assembly 500, the polishing liquid supply system 600, and the ultraviolet light generating device 300 of the present embodiment are disposed on the frame 100, which is advantageous to the integrity of the apparatus.

In this implementation, workpiece tray motion assembly 400 includes a workpiece tray 480, a connecting flange 470, a workpiece tray drive spindle 460, a workpiece tray drive 450, and a yaw mechanism, workpiece tray 480 is used to load workpiece 100, workpiece tray 480 is connected to workpiece tray drive spindle 460 through connecting flange 470, and workpiece tray drive 450 is connected to workpiece tray drive spindle 460 to drive workpiece tray drive spindle 460 to rotate; the deflection mechanism comprises a deflection rod 420 and a deflection slider 430, the deflection rod 420 is parallel to the polishing disk 520, the workpiece disk driver 450 is connected to the deflection slider 430, and the deflection slider 430 is movably connected to the deflection rod 420, so that the workpiece disk 480 can move left and right to realize deflection of the workpiece 100. In addition, the swing rod 420 of the present embodiment is a lead screw, the workpiece tray moving assembly 400 further includes a swing driver 400, the swing driver 400 is a motor, and the swing rod 420 is connected to the output end of the swing driver 400 to drive the swing rod 420 to rotate, so as to realize the movement of the swing slider 430 on the swing rod 420. The screw rod transmission device adopts a transmission mode of a rotary servo motor and a ball screw, has the characteristic of high precision, and can accurately control the horizontal movement of the workpiece disc. The linear motor and the guide rail can be matched with each other, and the method has better speed control capability and transmission precision. In addition, the workpiece disk motion assembly 400 further comprises a pressure cylinder 440, the pressure cylinder 440 is connected to the deflection slider 430, and the workpiece disk driver 450 is connected to an output end of the pressure cylinder 440, and drives the workpiece 100 to move up and down through the extension length of the output end of the pressure cylinder 440, so as to control the pressure between the polishing pad 510 and the workpiece 100.

The polishing disk motion assembly 500 comprises a polishing pad 510, a polishing disk 520, a polishing disk drive spindle 530, a polishing disk drive spindle pulley 540, a belt 550, a polishing disk drive pulley 560, and a polishing disk drive 570, wherein the polishing pad 510 is bonded to the polishing disk 520, is capable of carrying and storing a quantity of polishing fluid, and is in direct contact with the workpiece 100; one end of the polishing disk drive spindle 530 is connected to the polishing disk 520, and the other end is connected to the polishing disk drive spindle pulley 540; the polishing disk drive spindle pulley 540 is connected to the polishing disk drive pulley 560 by a belt 550; the polishing disk drive pulley 560 is mounted on the polishing disk drive 570 and driven by the polishing disk drive 570 to control the rotation of the polishing disk drive spindle pulley 540, and the polishing disk drive spindle pulley 540 is configured to drive the polishing disk drive spindle 530 to rotate, further driving the polishing disk 520 and the polishing pad 510 to rotate, so that the workpiece 100 and the abrasive on the polishing pad 510 move relatively to each other to remove the surface material of the workpiece. The polishing disk driver 570 is connected with the polishing disk driving spindle 530 through belt wheel transmission, and the belt wheel transmission has the advantages of high stability, simple structure, convenience in maintenance, overload slipping and the like. The rotation of the driving wheel can be controlled by using the transmission modes such as gear transmission, motor direct drive and the like to control the movement of the polishing disk. The gear transmission precision is high, the speed change range is wide, and the rotation of the polishing disc can be accurately controlled conveniently; the motor is directly driven without a transmission mode, the transmission is stable, the structure is simple, and the noise is low. The polishing pad 510 of the present embodiment is a polyurethane polishing pad or a felt pad.

The polishing solution supply system further comprises a stirrer 620, the stirrer 620 is arranged on the polishing solution preparation device 610, and the stirrer 620 can stir the solution to uniformly mix the solution, so that the abrasive particles in the solution are prevented from settling and agglomerating under the action of gravity. The stirrer 620 of the present embodiment employs an ultrasonic magnetic stirrer. The polishing solution preparing apparatus 610 includes a photocatalytic reaction container 611 and a fenton reaction container 613, the photocatalytic reaction container 611 is used for placing the photocatalytic reaction solution 612, the fenton reaction container 613 is used for placing the fenton reaction solution 614, and the photocatalytic reaction container 611 and the fenton reaction container 613 are respectively placed on a stirrer 620. The conveying device comprises two peristaltic pumps 630 and a liquid pipeline 640, one ends of the two peristaltic pumps 630 respectively extend into the photocatalytic reaction container 611 and the fenton reaction container 613 through pipelines, the other ends of the two peristaltic pumps are connected with the liquid pipeline 640, and the liquid pipeline 640 extends to the upper side of the polishing disc 520 and is used for conveying the photocatalytic reaction liquid 612 and the fenton reaction liquid 614 to the polishing disc 520. In this embodiment, the photocatalytic reaction solution 612 and the fenton reaction solution 614 are separately contained in two containers, and are respectively irradiated by ultraviolet light, and then are input to the polishing pad 520 together, which has the advantages of slower speed of hydroxyl radicals generated by chemical reaction, less loss in the liquid pipeline, capability of oxidizing more workpieces in the polishing pad 520, and higher utilization efficiency of the polishing solution. It should be noted that, alternatively, the polishing liquid supply system 600 may employ only one container, and the two reaction liquids may be mixed and placed in the same container, and the photocatalytic reaction may be directly performed using the ultraviolet irradiation device, which is advantageous in that the photocatalytic reaction may directly promote Fe³⁺To Fe²⁺Without a straight directionAdding Fe into Fenton reaction solution₃O₄And the chemical reaction efficiency of the mixed liquid is improved.

The ultraviolet light generating device 300 comprises an ultraviolet light generator 310, an optical fiber 320, an ultraviolet light emitting head 330 and a bracket 340, wherein the ultraviolet light generator 310 is used for generating ultraviolet light with the wavelength less than 365nm, the ultraviolet light generator 310 is connected with the ultraviolet light emitting head 330 through the optical fiber 320, the ultraviolet light emitting head 330 is provided with a fly eye lens, the ultraviolet light emitting head 330 can be movably connected to the bracket 340 along the direction close to or far away from the polishing solution preparation device 610, the ultraviolet light emitting head 330 of the embodiment can be connected to the bracket 340 in a manner of moving up and down and left and right, the distance between the ultraviolet light emitting head 330 and the liquid level of the polishing solution can be adjusted, and further the unit illumination intensity of a composite polishing solution and an ultraviolet light contact zone can be controlled. The size, shape and uniformity of light intensity in the light spot can be adjusted by the fly-eye lens.

Furthermore, the method is simple. The polishing device of the present embodiment further includes a control panel 700 for human-computer interaction, and setting and controlling related parameters such as ultraviolet intensity, polishing solution flow rate, polishing pressure, workpiece disk rotation speed, and polishing disk rotation speed.

In summary, embodiments of the present invention provide a composite polishing method for a diamond wafer, which can accelerate H under irradiation of ultraviolet light by irradiating a fenton reaction solution with ultraviolet light₂O₂The decomposition of the solution generates additional hydroxyl free radical OH, increases the concentration of the hydroxyl free radical OH in the Fenton reaction system, and accelerates the Fe³⁺Reduction to Fe²⁺The rate of (3) is higher than that of (3), more hydroxyl radicals OH are generated, and Fe in Fenton reaction is increased²⁺And Fe³⁺The conversion rate between the two is higher, so that the hydroxyl radical OH with the same dosage can carry out oxidation reaction with the workpiece, the removal of the surface material of the workpiece by abrasive particles in the polishing process is accelerated, the polishing efficiency of the diamond wafer can be effectively improved, and the surface quality is improved. In addition, a photocatalytic reaction liquid and the illuminated Fenton reaction liquid can be added to serve as a composite polishing liquid, so that the polishing effect is further improved. The embodiment also provides a polishing processing device for realizing the method.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A composite polishing processing method of a diamond wafer is characterized by comprising the following steps:

the method comprises the following steps: preparing a Fenton reaction solution;

2. The diamond wafer composite polishing processing method according to claim 1, further comprising, in the first step, preparing a photocatalytic reaction solution; in the second step, ultraviolet light is adopted to irradiate the prepared Fenton reaction solution and photocatalytic reaction solution in the first step; in the third step, the Fenton reaction solution and the photocatalytic reaction are both delivered to the polishing pad.

3. The composite polishing method for diamond wafers according to claim 1, wherein the Fenton reaction solution is composed of a first base solution, first abrasive grains, a Fenton reaction catalyst, and H₂O₂And deionized water.

4. The composite polishing method for diamond wafers according to claim 2, wherein the photocatalytic reaction solution is prepared by mixing a second base solution, second abrasive grains, a photocatalyst, an electron trapping agent, and a pH adjusting agent.

5. The composite polishing method for diamond wafer as set forth in claim 1, wherein in the second step, the intensity of the ultraviolet light is 500mW/cm²-1500mW/cm²。

6. A diamond wafer composite polishing processing device is characterized by comprising:

the workpiece disc moving assembly (400), the workpiece disc moving assembly (400) is used for loading the workpiece (100) and driving the workpiece (100) to rotate;

a polishing disk motion assembly (500), the polishing disk motion assembly (500) comprising a polishing pad (510) and a polishing disk (520), the polishing pad (510) being carried on the polishing disk (520);

a polishing liquid supply system (600), wherein the polishing liquid supply system (600) comprises a polishing liquid preparation device (610) and a conveying device for conveying liquid in the polishing liquid preparation device (610) to the polishing disc (520);

the ultraviolet light generating device (300), the ultraviolet light generating device (300) is used for generating ultraviolet light and irradiating on the polishing solution preparation device (610).

7. The diamond wafer composite polishing processing device according to claim 6, wherein the workpiece disk motion assembly (400) comprises a workpiece disk (480), an attachment flange (470), a workpiece disk drive spindle (460), a workpiece disk drive (450), and a yaw mechanism, the workpiece disk (480) being used for loading a workpiece (100), the workpiece disk (480) being connected to the workpiece disk drive spindle (460) through the attachment flange (470), the workpiece disk drive (450) being connected to the workpiece disk drive spindle (460) to rotate the workpiece disk drive spindle (460);

the deflection mechanism comprises a deflection swing rod (420) and a deflection slider (430), the deflection swing rod (420) is parallel to the polishing disk (520), the workpiece disk driver (450) is connected to the deflection slider (430), and the deflection slider (430) is movably connected to the deflection swing rod (420).

8. The diamond wafer composite polishing apparatus according to claim 7, wherein said workpiece disk motion assembly (400) further comprises a pressure cylinder (440), said pressure cylinder (440) being connected to said yaw slider (430), said workpiece disk drive (450) being connected to an output of said pressure cylinder (440).

9. The diamond wafer composite polishing processing device according to claim 6, wherein the polishing liquid supply system (600) further comprises an agitator (620), and the agitator (620) is provided on the polishing liquid preparation device (610).

10. The diamond wafer composite polishing processing device according to claim 6, wherein the ultraviolet light generating device (300) comprises an ultraviolet light generator (310), an optical fiber (320), an ultraviolet light emitting head (330), and a support (340), the ultraviolet light generator (310) is used for generating ultraviolet light, the ultraviolet light generator (310) is connected with the ultraviolet light emitting head (330) through the optical fiber (320), the ultraviolet light emitting head (330) is provided with a fly eye lens, and the ultraviolet light emitting head (330) is movably connected on the support (340) in a direction close to or far from the container.