A semiconductor material polishing method based on photothermal coupling catalysis and its application

Abstract

The present invention discloses a semiconductor material polishing method and application based on photothermal coupling catalysis, which belongs to the field of chemical mechanical polishing methods. Black titanium dioxide is used as a photothermal catalyst, mixed with a dispersant, an electron capture agent, and an abrasive to obtain a photothermal coupling polishing liquid, and a visible light source is used to irradiate the photothermal coupling polishing liquid, and polishing parameters are adjusted to perform polishing. The present invention uses photothermal coupling polishing technology, uses black titanium dioxide as a photothermal catalyst, expands the ultraviolet light source of traditional photocatalytic polishing technology to visible light sources and near-infrared light sources for photothermal coupling catalytic polishing, and based on the precise regulation of polishing liquid formula and polishing process parameters, the material removal rate can reach 142.9 nm / min, and the average surface roughness can reach 0.420 nm, achieving efficient and high-precision mirror polishing, and reducing energy loss in transmission and conversion, ensuring the stability and consistency of polishing quality, and can flexibly adapt to various non-oxide semiconductor materials.

Description

Technical Field

[0001] The present invention relates to the field of chemical mechanical polishing methods, and in particular to a semiconductor material polishing method based on photothermal coupling catalysis and an application thereof. Background Art

[0002] Semiconductors refer to materials with electrical conductivity between conductors and insulators at room temperature. Semiconductors are used in integrated circuits, consumer electronics, communication systems, photovoltaic power generation, lighting, high-power power conversion and other fields. For example, diodes are devices made of semiconductors. Common semiconductor materials include silicon, germanium, gallium arsenide, etc. Silicon is the most influential one in various semiconductor material applications. The above application fields require silicon to have an ultra-smooth, damage-free surface, so polishing technology is needed to effectively treat the surface.

[0003] Traditional polishing methods have problems such as low material removal rate and abrasive agglomeration. Photocatalytic polishing is a new polishing technology that can effectively improve polishing rate and efficiency. It usually uses ultraviolet light to excite photocatalytic materials such as titanium dioxide to form highly active oxidizing species, forming a softening layer on the surface of the silicon wafer and decomposing organic matter, which helps to remove abrasives in the polishing liquid during chemical mechanical polishing. However, the light source of traditional photocatalytic polishing is limited to ultraviolet cold light, and the catalyst used in the polishing liquid formula is also a catalyst that can only absorb ultraviolet light to produce catalytically active species. The photocatalytic efficiency and rate are still limited, so the research on synergistic technology based on traditional chemical mechanical polishing technology is the main research direction.

[0004] Photothermal catalysis is an emerging catalytic technology in recent years. It combines photochemical reactions and thermal effects, so it is often called photothermal coupled catalysis or photothermal synergistic catalysis. In addition to using ultraviolet light, photothermal catalysis can also use a wide range of visible and near-infrared light to generate carriers that enable the system to cross the reaction energy barrier and start related reaction processes, or generate heat energy through the photothermal effect, causing the local temperature to rise sharply, accelerating the thermal motion rate of atoms and molecules, and enhancing the activity of chemical reactions. Therefore, photothermal catalysis is a new type of high-efficiency catalytic technology that is different from traditional photocatalysis. It has received widespread attention in environmental and energy catalysis such as the decomposition of harmful gases, carbon dioxide reduction, and water decomposition to produce hydrogen. However, the application of photothermal catalysis in the polishing process has not yet been reported.

[0005] In order to achieve catalytic polishing, in addition to the conventional polishing liquid components, efficient catalytic materials are required. For example, in traditional photocatalytic polishing, TiO 2 It was found that it can produce highly oxidizing ·OH at room temperature, causing the surface of the silicon wafer to decompose into SiO 2 and CO 2 , and finally a nanoscale surface can be obtained, but the decomposition rate is very low. As the research progresses, it is found that ultraviolet light can promote the decomposition of TiO 2Rapidly generate a large amount of ·OH, so ultraviolet light began to be widely used in photocatalytic polishing of single crystal silicon. With the development of the field of photocatalysis, more efficient titanium dioxide materials gradually replaced traditional crystalline titanium dioxide. For example, P25 is a mixed crystalline titanium dioxide, which can be excited under ultraviolet light to generate electrons and holes that can be separated more effectively, promoting photocatalytic reactions. However, its light utilization range is narrow and is only suitable for traditional photocatalysis.

[0006] At present, although photocatalytic polishing is a popular method in chemical mechanical semiconductor polishing technology, its photocatalytic efficiency and polishing rate are still limited. And although the polishing process is driven by photocatalytic reaction, it still consumes a lot of chemical reagents, causing pollution and damage to the environment. Therefore, combining photothermal coupling catalytic technology to solve the problems existing in the existing chemical mechanical polishing technology and improve polishing efficiency is an urgent problem to be solved in the current semiconductor polishing field. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a semiconductor material polishing method and application based on photothermal coupling catalysis. Based on the photothermal coupling catalysis technology, by regulating the photothermal coupling polishing liquid, light source parameters and polishing parameters, a layer-by-layer, uniform and fine material removal process is achieved, while improving the polishing efficiency. At the same time, it is flexibly adapted to the polishing requirements of various non-oxide semiconductor materials, breaking through the limitations of existing polishing technology in material applicability.

[0008] A semiconductor material polishing method based on photothermal coupled catalysis comprises the following steps:

[0009] (1) adding a photothermal catalyst, a dispersant, an electron capture agent, and an abrasive into deionized water, stirring and ultrasonicating, to obtain a photothermal coupled polishing liquid, wherein the photothermal catalyst is black titanium dioxide;

[0010] (2) Fix the semiconductor material to be polished on the polishing disk of the polishing machine, use a visible light source to irradiate the photothermal coupling polishing liquid, and make the photothermal coupling polishing liquid drop and contact the semiconductor material to be polished, adjust the light source parameters or polishing parameters to polish the semiconductor material to be polished.

[0011] The present invention prepares a photothermal coupling polishing liquid for polishing based on black titanium dioxide as a photothermal catalyst. The wide-spectrum property of black titanium dioxide is utilized to expand the ultraviolet light source of traditional photocatalytic polishing technology to the visible and near-infrared light regions of photothermal coupling catalysis. At the same time, the characteristics of light and heat are combined to drive the catalytic reaction under elevated temperature with a wide spectrum to generate more photogenerated electron holes. The temperature of the reaction operation will also be significantly increased, thereby achieving high catalytic efficiency. After the wide-spectrum light is irradiated onto the polishing liquid, photothermal conversion is carried out, and the heat is accurately utilized by the photothermal catalyst and the surface of the semiconductor material. At the same time, the additional catalytic effect of photochemistry is superimposed, thereby improving the polishing efficiency and polishing accuracy.

[0012] Preferably, the preparation method of black titanium dioxide comprises: mixing and grinding P25 titanium dioxide and sodium borohydride, followed by calcining, cooling to room temperature after calcination, ultrasonically cleaning and drying to obtain black titanium dioxide, wherein the mass ratio of P25 titanium dioxide to sodium borohydride is 0.3~3:1.

[0013] Further preferably, the mass ratio of P25 titanium dioxide to sodium borohydride is 2:1.

[0014] Preferably, the mixing and grinding time is 10 min to 30 min.

[0015] Grinding P25 titanium dioxide and sodium borohydride within the above-mentioned mixing and grinding time can make the mixing and grinding sufficient, so as to facilitate the subsequent annealing treatment to be more sufficient.

[0016] More preferably, the mixing and grinding time is 10 min to 20 min.

[0017] Preferably, the calcination temperature is 300°C to 360°C.

[0018] By selecting the appropriate range of calcination temperature and calcination time, P25 titanium dioxide is completely reduced by sodium borohydride without producing other impurities such as titanium trioxide, thereby ensuring the purity of the photothermal catalyst.

[0019] More preferably, the calcination temperature is 330° C. and the calcination time is 1 h.

[0020] Under the same conditions, the black nano-titanium dioxide prepared at a calcination temperature of 330 °C has the highest heating rate under the irradiation of visible light source and the best photothermal catalytic efficiency.

[0021] Preferably, the calcination atmosphere is argon gas, and the flow rate of argon gas is 150 mL / min.

[0022] Preferably, the concentration of the photothermal catalyst in the photothermal coupled polishing liquid is 0.25 g / L to 2.0 g / L.

[0023] The photothermal catalyst within the above concentration range produces more reducing hydroxyl radicals and superoxide radicals for polishing under light conditions, which helps to improve the photothermal polishing efficiency, and also improves the surface polishing quality and reduces scratches and pits.

[0024] Further preferably, the concentration of the photothermal catalyst in the photothermal coupling polishing liquid is 1.0 g / L.

[0025] Preferably, the dispersant is one or more of alkali metal phosphates, silicates, low molecular weight polycarboxylates, and anionic surfactants.

[0026] Selecting a suitable dispersant can significantly improve the uniformity of the polishing process, disperse the particles well, and promote a more uniform distribution of the polishing liquid on the workpiece surface, thereby avoiding over-polishing or under-polishing caused by excessive local concentration, and effectively reducing scratches and surface defects generated during the polishing process, improving polishing efficiency and greatly reducing the defective rate.

[0027] More preferably, the dispersant is sodium hexametaphosphate.

[0028] Preferably, the concentration of the dispersant is 0.5 g / L to 3.0 g / L.

[0029] More preferably, the concentration of the dispersant is 2.0 g / L.

[0030] Preferably, the electron capture agent is one or more of hydrogen peroxide, potassium permanganate, and persulfate.

[0031] Selecting a suitable electron capture agent can regulate the recombination rate of photogenerated carriers and form an oxide film on the surface of the polished workpiece. The oxide film on the raised part of the polished workpiece is ground off by mechanical action, and the oxide film on the pits is prevented from further corrosion, which is beneficial to subsequent mechanical polishing, thereby improving polishing efficiency and surface flatness.

[0032] More preferably, the electron capture agent is hydrogen peroxide.

[0033] Preferably, the volume percentage of the electron capture agent in the photothermal coupling polishing liquid is 5% to 30%.

[0034] The appropriate concentration of electron-trapping agent helps to maintain the efficient progress of the photothermal catalytic reaction and promote the synergistic effect of photothermal coupled catalysis, thereby improving the polishing accuracy, efficiency and final surface quality.

[0035] Further preferably, the volume percentage of the electron capture agent in the photothermal coupling polishing liquid is 10%.

[0036] Preferably, the abrasive is silica sol, Al 2 O 3 Particles, SiO 2 One or more of the particles; the particle size of the abrasive is 40 nm~150 nm.

[0037] Selecting the right abrasive can make it possible to remove the products of the chemical reaction layer with weaker bonding force with only a small mechanical action during the polishing process, thereby reducing or avoiding polishing surface defects; in addition, abrasives with appropriate particle size can obtain better polishing surface quality.

[0038] Preferably, the semiconductor material may be selected from existing single crystal silicon wafers, silicon carbide, gallium nitride or diamond.

[0039] Preferably, the visible light source is sunlight, concentrated sunlight, a xenon lamp, a halogen tungsten lamp, a mercury lamp or an LED lamp.

[0040] During the photothermal polishing process, due to its own wide-spectrum characteristics, the light source of the photothermal catalyst can be expanded from the previous ultraviolet light to the visible light region. Under the irradiation of the visible light source, the photothermal catalyst black titanium dioxide can produce more photogenerated electrons and holes, which is beneficial to photochemical reactions. At the same time, it has a more significant photothermal effect, thereby increasing the temperature and the reaction rate, realizing the full utilization of solar energy and saving energy.

[0041] Further preferably, the visible light source is a xenon lamp.

[0042] Preferably, the light source parameters include light source current, and the light intensity is indirectly controlled by controlling the xenon lamp current.

[0043] The light source current is 13 A~21 A, and the corresponding light source intensity is 750 W / m 2 ~1400 W / m 2 .

[0044] The light source is controlled by electric current, and the current is adjusted to obtain the appropriate light intensity. The appropriate light intensity can ensure that the photothermal catalyst black titanium dioxide fully absorbs photon energy and produces sufficient thermal effect to promote photothermal catalysis, thereby ensuring excellent polishing rate and effect without causing local overheating of the polished workpiece, destroying the uniformity of the microstructure of the material surface, and consuming energy.

[0045] Further preferably, the light source current is 21 A, and the corresponding light intensity is 1375.8 W / m 2 Polishing is performed at the light source intensity corresponding to this light source current, and the polishing efficiency is the highest, and mirror polishing can be achieved.

[0046] Preferably, the polishing parameters include polishing pressure, polishing machine rotation speed and polishing time.

[0047] The polishing pressure is 200 g / cm 2 ~400 g / cm 2 .

[0048] Appropriate polishing pressure helps to maintain good contact between the polishing tool and the surface of the semiconductor material to be polished, promotes the full removal of the semiconductor material under the action of photothermal catalysis, and forms an ideal chemical mechanical polishing state of "polishing pad-substrate surface-abrasive particles" three-body contact, so that the flow of the polishing liquid on the substrate surface is unrestricted, and the mass transfer effect and wetting ability of the polishing liquid are maintained, so that impurities on the surface of the semiconductor material can be removed without causing damage to the material surface or increasing the wear of the polishing tool, thereby obtaining excellent surface roughness.

[0049] Further preferably, the polishing pressure is 300 g / cm 2 .

[0050] The polishing machine has a rotation speed of 35 r / min to 75 r / min.

[0051] The speed of the polishing machine affects the uniformity and efficiency of polishing. A reasonable speed can make the polishing liquid evenly distributed on the surface of the polishing material and participate in the reaction without causing waste of the polishing liquid, thereby increasing the polishing rate and material removal rate while reducing energy consumption.

[0052] Further preferably, the polishing machine has a rotation speed of 55 r / min.

[0053] The polishing time is at least 30 min.

[0054] The polishing time directly determines the length of time the abrasive interacts with the workpiece surface, which in turn affects the amount of material removed, surface roughness, and polishing quality. Appropriate polishing time helps to further remove surface defects, improve surface finish, avoid unnecessary over-polishing, save processing costs, and reduce production cycles.

[0055] The present invention also provides application of the semiconductor material polishing method based on photothermal coupling catalysis in semiconductor material polishing.

[0056] Compared with the prior art, the beneficial effects of the present invention are at least:

[0057] (1) Through the precise control of the polishing liquid formula based on black titanium dioxide and the polishing process parameters, the light energy can be efficiently converted into heat energy and directly act on the material surface during the polishing process, greatly improving the polishing efficiency. The material removal rate can reach 142.9 nm / min, and the average surface roughness can reach 0.420 nm, achieving efficient and high-precision mirror polishing. At the same time, it reduces energy consumption and pollution during the polishing process, opening up a new path for efficient, green and high-precision surface treatment.

[0058] (2) By preparing black titanium dioxide as a photothermal catalyst, more electrons and holes can be generated, and the ultraviolet light source of traditional photocatalytic polishing technology can be expanded to the visible light source and near-infrared light source of photothermal coupled catalytic polishing, providing a precise and controllable energy input method, broadening the application scenarios of the polishing process, and being able to adapt to the polishing needs of workpieces of different materials, shapes and sizes, improving the flexibility and reliability of the process, and ensuring the stability and consistency of the polishing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a heating rate curve of black titanium dioxide and P25 type titanium dioxide solution synthesized at different temperatures under xenon light.

[0060] Figure 2 This is a diagram of the temperature change of the black titanium dioxide-based photothermal coupled polishing liquid during the polishing process under different xenon lamp current conditions.

[0061] Figure 3 This is a diagram of the temperature change of the P25 titanium dioxide based polishing liquid during the polishing process under different xenon lamp current conditions.

[0062] Figure 4 The figure is a comparison chart of the polishing rates of the polishing liquids prepared in Example 1 and Comparative Example 1 under different xenon lamp current conditions. DETAILED DESCRIPTION

[0063] The specific implementation of the present invention is further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are any processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art.

[0064] Example 1

[0065] (1) Preparation of black titanium dioxide with photothermal catalytic properties

[0066] Weigh 4.0 g of white titanium dioxide P25 and 2.0 g of sodium borohydride respectively and place them in a mortar for mixing and grinding for 15 min. After grinding, take them out and place them in a tube furnace at a heating rate of 10 °C / min. Figure 1As shown, the temperature is raised from 30 ℃ for 33 minutes to 360 ℃, then kept warm for 1 hour and cooled with the furnace. During this period, argon gas is introduced into the tubular furnace with an argon flow rate of 150 mL / min. After cooling to room temperature, it is taken out from the burning boat and placed in a centrifuge tube. Deionized water is added to 40 mL of the centrifuge tube, and it is placed in an ultrasonic machine for ultrasonication for 10 minutes. The centrifuge is taken out and placed in a centrifuge with a speed set at 10000 r / min for centrifugation for 5 minutes. Subsequently, it is washed with deionized water and anhydrous ethanol respectively, and finally stored in a vacuum drying oven for 24 hours to obtain black titanium dioxide with photothermal catalytic properties as a photothermal catalyst.

[0067] (2) Configure photothermal coupling polishing liquid

[0068] Weigh 2.0 g of sodium hexametaphosphate and 1.0 g of Al with a particle size of 400 nm. 2 O 3 The particles and 1.0 g of the black titanium dioxide synthesized in step (1) are mixed and placed in a beaker. 700 mL of deionized water, 200 mL of silica sol with a particle size of 100 nm and 100 mL of hydrogen peroxide are added to the beaker. After stirring evenly, the mixture is placed in an ultrasonic machine for 15 min to obtain a uniform photothermal coupling polishing liquid.

[0069] (3) Polishing silicon wafers using photothermal coupled polishing fluid

[0070] The UNIPOL-1502 polishing machine produced by Shenyang Kejing was used to stick the silicon wafer on the polishing disc of the polishing machine with wax, and then the polishing disc was fixed on the polishing head of the polishing machine. The polishing pad was a non-woven polishing pad with a fluff structure. The xenon lamp light source (simulated sunlight) was turned on to irradiate the photothermal coupling polishing liquid. The xenon lamp was used as a simulated sunlight light source to irradiate the photothermal coupling polishing liquid to generate hydroxyl radicals for chemical reaction, so that the photothermal coupling polishing liquid slowly dripped and contacted the surface of the silicon wafer for grinding. The polishing pressure was 300 g / cm 2 , the polishing machine speed is 55 r / min, and the xenon lamp current is 21 A ( Figure 2 ), corresponding to a light intensity of 1375.8 W / m 2 The polishing time is 30 min. A precision balance is used to record the quality of silicon wafers before and after polishing to calculate the material removal rate, and a NewView 8200 white light interferometer is used to measure the surface roughness of silicon wafers.

[0071] The material removal rate of the silicon wafer after photothermal coupling polishing is 148.9 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.420 nm, and the highest temperature during the polishing process is 30.5 ℃.

[0072] Example 2

[0073] The steps of Example 2 are the same as those of Example 1, except that: in step (1), black titanium dioxide ( Figure 1 ).

[0074] The material removal rate of the silicon wafer after photothermal coupling polishing is 102.8 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.392 nm, and the highest temperature during the polishing process is 30.0 ℃.

[0075] Example 3

[0076] The steps of Example 3 are the same as those of Example 1, except that: in step (1), black titanium dioxide ( Figure 1 ).

[0077] The material removal rate of the silicon wafer after photothermal coupling polishing is 121.7 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.424 nm, and the highest temperature during the polishing process is 30.1 ℃.

[0078] Example 4

[0079] The steps of Example 4 are the same as those of Example 1, except that: in step (1), black titanium dioxide ( Figure 1 ).

[0080] The material removal rate of the silicon wafer after photothermal coupling polishing is 115.9 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.462 nm, and the highest temperature during the polishing process is 29.2 ℃.

[0081] Example 5

[0082] The steps of Example 5 are the same as those of Example 1, except that: in step (1), black titanium dioxide ( Figure 1 ).

[0083] The material removal rate of the silicon wafer after photothermal coupling polishing is 147.3 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.438 nm, and the highest temperature during the polishing process is 30.0 ℃.

[0084] Example 6

[0085] The steps of Example 6 are the same as those of Example 1, except that the weight of black titanium dioxide added in step (2) is 0.25 g, and the concentration of the corresponding polishing liquid is 0.25 g / L.

[0086] The material removal rate of the silicon wafer after photothermal coupling polishing is 81.6 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.425 nm, and the highest temperature during the polishing process is 29.1℃.

[0087] Example 7

[0088] The steps of Example 7 are the same as those of Example 1, except that the weight of black titanium dioxide added in step (2) is 2.0 g, and the concentration of the corresponding polishing liquid is 2.0 g / L.

[0089] The material removal rate of the silicon wafer after photothermal coupling polishing is 103.5 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.398 nm, and the highest temperature during the polishing process is 30.7℃.

[0090] Example 8

[0091] The steps of Example 8 are the same as those of Example 1, except that in step (3), the xenon lamp current is 13 A, corresponding to a light intensity of 789.8 W / m 2 .

[0092] like Figure 2 and Figure 4 As shown in the figure, the material removal rate of the silicon wafer after photothermal coupling polishing is 91.85 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.465 nm, and the highest temperature during the polishing process is 29.0 ℃.

[0093] Example 9

[0094] The steps of Example 9 are the same as those of Example 1, except that in step (3), the xenon lamp current is 15 A, corresponding to a light intensity of 891.7 W / m 2 .

[0095] like Figure 2 and Figure 4 As shown in the figure, the material removal rate of the silicon wafer after photothermal coupling polishing is 112.0 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.428 nm, and the highest temperature during the polishing process is 29.2 ℃.

[0096] Example 10

[0097] The steps of Example 10 are the same as those of Example 1, except that in step (3), the xenon lamp current is 17 A, corresponding to a light intensity of 1006.4 W / m 2 .

[0098] like Figure 2 and Figure 4 As shown in the figure, the material removal rate of the silicon wafer after photothermal coupling polishing is 116.6 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.422 nm, and the highest temperature during the polishing process is 30.2 ℃.

[0099] Embodiment 11

[0100] The steps of Example 11 are the same as those of Example 1, except that in step (3), the xenon lamp current is 19 A, corresponding to a light intensity of 1172.0 W / m 2 .

[0101] like Figure 2 and Figure 4 As shown in the figure, the material removal rate of the silicon wafer after photothermal coupling polishing is 127.3 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.374 nm, and the highest temperature during the polishing process is 30.2 ℃.

[0102] Example 12

[0103] The steps of Example 12 are the same as those of Example 1, except that the polishing pressure in step (3) is 200 g / cm 2 .

[0104] The material removal rate of the silicon wafer after photothermal coupling polishing is 104.3 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.514 nm, and the highest temperature during the polishing process is 30.3 ℃.

[0105] Example 13

[0106] The steps of Example 13 are the same as those of Example 1, except that the polishing pressure in step (3) is 400 g / cm 2 .

[0107] The material removal rate of the silicon wafer after photothermal coupling polishing is 135.7 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.414 nm, and the highest temperature during the polishing process is 29.8 ℃.

[0108] Embodiment 14

[0109] The steps of Example 14 are the same as those of Example 1, except that the polishing machine speed in step (3) is 35 r / min.

[0110] The material removal rate of the silicon wafer after photothermal coupling polishing is 95.0 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.519 nm, and the highest temperature during the polishing process is 31.2 ℃.

[0111] Embodiment 15

[0112] The steps of Example 15 are the same as those of Example 1, except that the polishing machine speed in step (3) is 75 r / min.

[0113] The material removal rate of the silicon wafer after photothermal coupling polishing is 112.8 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.479 nm, and the highest temperature during the polishing process is 28.8 ℃.

[0114] Comparative Example 1

[0115] (1) Preparation of P25 titanium dioxide based polishing liquid

[0116] Weigh 2.0 g of sodium hexametaphosphate and 1.0 g of Al with a particle size of 400 nm. 2 O 3 The particles and 1.0 g of P25 titanium dioxide were mixed and put into a beaker. 700 mL of deionized water, 200 mL of silica sol with a particle size of 100 nm and 100 mL of hydrogen peroxide were added into the beaker. After stirring evenly, the mixture was put into an ultrasonic machine for 15 min to obtain a uniform polishing liquid.

[0117] (2) Polishing silicon wafers using P25 titanium dioxide polishing liquid

[0118] Use Shenyang Kejing's UNIPOL-1502 polishing machine, stick the silicon wafer on the polishing disc of the polishing machine with wax, and then fix the polishing disc on the polishing head of the polishing machine. The polishing pad is a non-woven polishing pad with a fluff structure. Turn on the xenon lamp light source (simulating sunlight) to irradiate the polishing liquid. Use the xenon lamp as a simulated sunlight light source to irradiate the polishing liquid to generate hydroxyl radicals for chemical reaction, so that the polishing liquid slowly drips and contacts the surface of the silicon wafer for grinding. The polishing pressure is 300 g / cm 2 , the polishing machine speed is 55 r / min, and the xenon lamp current is 21 A ( Figure 3 ), corresponding to a light intensity of 1375.8 W / m 2 The polishing time is 30 min. A precision balance is used to record the quality of silicon wafers before and after polishing to calculate the material removal rate, and a NewView 8200 white light interferometer is used to measure the surface roughness of silicon wafers.

[0119] like Figure 3 and Figure 4As shown, the results show that after polishing the silicon wafer with the P25 titanium dioxide-based polishing liquid, the material removal rate is 94.5 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.403 nm, and the highest temperature during the polishing process is 22.9 ℃.

[0120] Comparative Example 2

[0121] The steps of Comparative Example 2 are the same as those of Comparative Example 1, except that in step (2), the xenon lamp current is 13 A, corresponding to a light intensity of 789.8 W / m 2 .

[0122] like Figure 3 and Figure 4 As shown in the figure, the material removal rate of the silicon wafer after photothermal coupling polishing is 81.6 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.388 nm, and the highest temperature during the polishing process is 22.0 ℃.

[0123] Comparative Example 3

[0124] The steps of comparative example 3 are the same as those of comparative example 1, except that in step (2), the xenon lamp current is 15 A, corresponding to a light intensity of 891.7 W / m 2 .

[0125] like Figure 3 and Figure 4 As shown in the figure, the material removal rate of the silicon wafer after photothermal coupling polishing is 79.7 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.378 nm, and the highest temperature during the polishing process is 22.9 ℃.

[0126] Comparative Example 4

[0127] The steps of Comparative Example 4 are the same as those of Comparative Example 1, except that in step (2), the xenon lamp current is 17 A, corresponding to a light intensity of 1006.4 W / m 2 .

[0128] like Figure 3 and Figure 4 As shown in the figure, the material removal rate of the silicon wafer after photothermal coupling polishing is 90.2 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.363 nm, and the highest temperature during the polishing process is 21.1 ℃.

[0129] Comparative Example 5

[0130] The steps of Comparative Example 5 are the same as those of Comparative Example 1, except that in step (2), the xenon lamp current is 19 A, corresponding to a light intensity of 1172.0 W / m 2.

[0131] like Figure 3 and Figure 4 As shown in the figure, the material removal rate of the silicon wafer after photothermal coupling polishing is 95.0 nm / min, the average surface roughness Sa of the selected area 100 μm*100 μm is 0.425 nm, and the highest temperature during the polishing process is 23.8 ℃.

Claims

1. A semiconductor material polishing method based on photothermal coupled catalysis, characterized in that: The following steps are involved: (1) adding a photothermal catalyst, a dispersant, an electron capture agent, and an abrasive into deionized water, stirring and ultrasonicating, to obtain a photothermal coupled polishing liquid, wherein the photothermal catalyst is black titanium dioxide; (2) Fixing the semiconductor material to be polished on the polishing disk of the polishing machine, irradiating the photothermal coupling polishing liquid with a visible light source, and making the photothermal coupling polishing liquid drop and contact the semiconductor material to be polished, and adjusting the light source parameters or polishing parameters to polish the semiconductor material to be polished; The light source parameters include light source current and light source intensity, and the polishing parameters include polishing pressure, polishing machine speed and polishing time; The light source current is 13 A~21 A, and the light source intensity is 750 W / m 2 ~1400 W / m 2 ; Or the polishing pressure is 200 g / cm 2 ~400 g / cm 2 The polishing machine speed is 35 r / min~75 r / min, and the polishing time is at least 30 min.

2. The semiconductor material polishing method based on photothermal coupling catalysis according to claim 1, characterized in that: The preparation method of black titanium dioxide comprises: mixing and grinding P25 titanium dioxide and sodium borohydride, calcining, cooling to room temperature after calcination, ultrasonically cleaning and drying to obtain black titanium dioxide, wherein the mass ratio of P25 titanium dioxide to sodium borohydride is 0.3-3:

1.

3. The semiconductor material polishing method based on photothermal coupled catalysis according to claim 2, characterized in that: The calcination temperature is 300°C to 360°C.

4. The semiconductor material polishing method based on photothermal coupled catalysis according to claim 1, characterized in that: The concentration of the photothermal catalyst in the photothermal coupled polishing liquid is 0.25 g / L~2.0 g / L.

5. The semiconductor material polishing method based on photothermal coupled catalysis according to claim 1, characterized in that: The dispersant is one or more of alkali metal phosphates, silicates, low molecular weight polycarboxylates, and anionic surfactants; The concentration of the dispersant is 0.5 g / L to 3.0 g / L.

6. The semiconductor material polishing method based on photothermal coupled catalysis according to claim 1, characterized in that: The electron capture agent is one or more of hydrogen peroxide, potassium permanganate, and persulfate; The volume percentage of the electron capture agent in the photothermal coupling polishing liquid is 5% to 30%.

7. The semiconductor material polishing method based on photothermal coupled catalysis according to claim 1, characterized in that: The abrasive is one or more of silica sol, Al2O3 particles, and SiO2 particles; The particle size of the abrasive is 40 nm to 150 nm.

8. The semiconductor material polishing method based on photothermal coupled catalysis according to claim 1, characterized in that: The visible light source is sunlight, concentrated sunlight, a xenon lamp, a halogen tungsten lamp, a mercury lamp or an LED lamp.

9. Application of the semiconductor material polishing method based on photothermal coupling catalysis according to any one of claims 1 to 8 in semiconductor material polishing.

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