Nanoscale composite grinding powder and grinding fluid for semiconductor double-sided grinding machine

Abstract

The invention relates to the technical field of semiconductor grinding processing, in particular to a semiconductor double-sided grinding machine nanoscale composite grinding powder which is composed of main grinding powder with the mass ratio being 70% and D50 being 150 nm and auxiliary grinding powder with the mass ratio being 30% and D50 being 50 nm, and coarse grinding and accurate grinding are integrated through particle size grading; the main grinding powder and the auxiliary grinding powder both have the following core-shell structures: a core layer: nanoscale silicon carbide particles with D50 of 80 nm and hardness of HV3200, and is used for providing a high material removal rate; the shell layer is a zirconium oxide coating layer with the thickness of 10-15nm and is used for reducing the agglomeration tendency of the grinding powder; and surface modification: grafting an organic functional group through a silane coupling agent to enhance the compatibility with a suspending agent.

Description

Technical Field

[0001] This invention relates to the field of semiconductor processing technology, and in particular to a nanoscale composite polishing powder and polishing fluid for a semiconductor double-sided polishing machine. Background Technology

[0002] Silicon single crystal grinding is an important process in the single crystal silicon wafer manufacturing line. Its main purposes are: to remove visually visible defects such as residual traces from the slicing process; to eliminate residual processing stress from the slicing process; to improve the surface uniformity, surface flatness, and local flatness of the edges of the ground product, thereby improving the surface accuracy of the silicon wafer; and to reduce the surface roughness of the silicon wafer. This lays the foundation for the final product to meet various testing indicators, thus ensuring the overall quality and yield of the finished product. Therefore, this places strict requirements on the grinding of 12-inch silicon wafers.

[0003] Existing double-sided polishing powders and slurries have the following defects: 1. Low grinding efficiency: Traditional alumina (Al2O3) grinding powder has a wide particle size distribution (D50=1-3μm), and the material removal rate (MRR) is <0.5μm / min; 2. Significant surface damage: Single-component grinding powder is prone to scratches and microcracks, resulting in a silicon wafer surface roughness Ra > 0.3 μm; 3. Poor suspension stability: The viscosity of the grinding slurry changes significantly with temperature, and the grinding powder is prone to sedimentation (sedimentation rate >30% after standing for 24 hours). 4. Environmental risks: Grinding fluids containing nitrites are prone to polluting water bodies, and the biodegradation rate is <50%.

[0004] Therefore, it is necessary to develop a new type of semiconductor double-sided polishing machine nanoscale composite polishing powder and polishing fluid to overcome the defects of traditional double-sided polishing powder. Summary of the Invention

[0005] This invention provides a nanoscale composite grinding powder and grinding fluid for a semiconductor double-sided polishing machine, which solves the technical bottlenecks of existing grinding powders in terms of processing efficiency, surface quality and cycle stability.

[0006] The technical solution of this invention is: a nanoscale composite grinding powder for a semiconductor double-sided polishing machine, comprising a main grinding powder (70% by mass, D50=150nm) and an auxiliary grinding powder (30% by mass, D50=50nm), achieving integrated coarse and fine grinding through particle size distribution; both the main grinding powder and the auxiliary grinding powder have the following core-shell structure: Core layer: Nanoscale silicon carbide particles, D50=80nm, hardness HV3200, used to provide high material removal rate; Shell: Zirconia coating, 10-15nm thick, used to reduce the tendency of grinding powder to agglomerate; Surface modification: Organic functional groups are grafted onto silane coupling agents to enhance compatibility with suspending agents.

[0007] Preferably, the silane coupling agent used is KH-570.

[0008] Preferably, the organic functional group is -CH3.

[0009] Another technical solution of the present invention is: a grinding fluid comprising the following components by mass percentage: The nano-scale composite grinding powder contains 50% of the following: The composite suspending agent comprises 48.5% of the following components: polyethylene glycol (PEG), used to adjust the viscosity of the grinding slurry to 15-25 mPa·s; sodium carboxymethyl cellulose (CMC), used to form a three-dimensional network structure and inhibit sedimentation; and sodium dodecylbenzene sulfonate (DMS), used to reduce the surface tension of the grinding slurry to 25 mN / m. The remainder is deionized water. The mass percentages of PEG, CMC, and DMS in the composite suspending agent are 40%, 15%, and 5%, respectively. Functional additives include: 0.5% nano-titanium dioxide with a particle size of 10nm, used for photocatalytic degradation of organic pollutants; and 1% biological buffer, used to stabilize the pH of the grinding slurry at 7.5±0.2.

[0010] The beneficial effects of this invention are: 1. Improved processing efficiency: The nano-scale composite grinding powder increases the material removal rate to 1.2μm / min, which is 140% higher than the traditional process; 2. Improved surface quality: The core-shell structure and gradation design reduce the surface roughness to Ra0.08μm and reduce the scratch density by 80%; 3. Improved cycle stability: The grinding slurry has a sedimentation rate of <5% after 7 days of standing, and can be recycled ≥15 times, reducing consumable costs by 60%; 4. Significant environmental performance: The biodegradability rate reaches 92%, and heavy metals are detected in zero, which meets the EHS standards of the semiconductor industry. Detailed Implementation

[0011] The technical solution of the invention will be further described in detail below through examples.

[0012] This embodiment provides a semiconductor double-sided polishing machine nanoscale composite polishing powder, composed of a main polishing powder and an auxiliary polishing powder. The main polishing powder has a D50 = 150 nm and accounts for 70% of the mass of the nanoscale composite polishing powder; the auxiliary polishing powder has a D50 = 50 nm and accounts for 30% of the mass of the nanoscale composite polishing powder. Through the particle size distribution of D50 = 150 nm and D50 = 50 nm, coarse grinding and fine grinding are integrated. Both the main polishing powder and the auxiliary polishing powder have the following core-shell structure: Core layer: Nanoscale silicon carbide (SiC) particles (D50=80nm), hardness HV3200, providing high material removal rate; Shell: Zirconia (ZrO2) coating (10-15nm thick) to reduce the tendency of grinding powder to agglomerate; Surface modification: Organic functional groups (-CH3) are grafted onto the silane coupling agent (KH-570) to enhance compatibility with the suspending agent.

[0013] This embodiment also provides a grinding fluid, the abrasive of which is the above-mentioned nano-scale composite grinding powder, wherein the main grinding powder has a mass percentage of 35% in the grinding fluid and the auxiliary grinding powder has a mass percentage of 15% in the grinding fluid.

[0014] The grinding fluid also contains the following environmentally friendly composite suspending agent, which accounts for 48.5% by mass in the grinding fluid, and its composition is as follows: Polyethylene glycol (PEG-400): 40% by mass in the suspending agent (adjust the viscosity of the grinding slurry to 15-25 mPa·s); Sodium carboxymethyl cellulose (CMC): 15% by mass in the suspending agent (used to form a three-dimensional network structure and inhibit sedimentation); Sodium dodecylbenzenesulfonate (SDBS): 5% by mass in the suspending agent (to reduce the surface tension of the grinding slurry to 25 mN / m); The remainder is deionized water.

[0015] The grinding fluid also contains the following functional additives, the composition of which is: Nano-titanium dioxide (TiO2, particle size 10nm): 0.5% by mass in the grinding slurry (its function is photocatalytic degradation of organic pollutants); Biological buffer (Tris-HCl): 1% by mass in the grinding slurry (to stabilize the pH of the grinding slurry at 7.5±0.2).

[0016] The synergistic mechanisms in the above-mentioned grinding fluids include: Mechanochemical composite action: The nano-SiC core layer removes material through mechanical friction; the zirconium oxide shell reacts with OH groups in the polishing slurry. - The reaction produces soluble zirconate, achieving chemical polishing; Suspension stability control: CMC and PEG-400 form a hydrogen bond network, and the sedimentation rate is <5% after standing for 7 days; SDBS reduces interfacial energy and improves the uniformity of powder dispersion (D90 / D10 < 1.5).

[0017] Example 1: Double-sided grinding of a 12-inch silicon wafer; 1. Preparation of grinding fluid: Weigh 200g of composite grinding powder (140g of main grinding powder + 60g of auxiliary grinding powder), add it to 194g of suspending agent, add 2g of nano titanium dioxide, and add 4g of biological buffer. Stir at 300 rpm for 30 minutes and ultrasonically disperse for 10 minutes to obtain a grinding slurry with pH=7.5 and solid content of 50.5%; 2. Grinding process parameters: Grinding pressure: 0.2 MPa; Grinding disc rotation speed: Upper disc 80 rpm / Lower disc 60 rpm; Grinding fluid flow rate: 1.5 L / min; Processing time: 20 minutes; 3. Test Results: Material removal rate (MRR): 1.2 μm / min (140% higher than traditional Al2O3 grinding powder); Surface roughness Ra: 0.08 μm (scratch density < 5 scratches / cm²); The grinding slurry can be recycled ≥15 times (COD removal rate >85%).

[0018] The environmental performance test results of the grinding fluid are shown in the table below:

[0019] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A nanoscale composite grinding powder for a semiconductor double-sided grinding machine, characterized in that: It consists of 70% main grinding powder (D50=150nm by mass) and 30% auxiliary grinding powder (D50=50nm by mass), achieving integrated coarse and fine grinding through particle size distribution; both the main and auxiliary grinding powders have the following core-shell structure: Core layer: Nanoscale silicon carbide particles, D50=80nm, hardness HV3200, used to provide high material removal rate; Shell: Zirconia coating, 10-15nm thick, used to reduce the tendency of grinding powder to agglomerate; Surface modification: Organic functional groups are grafted onto silane coupling agents to enhance compatibility with suspending agents.

2. The semiconductor double-sided polishing machine nanoscale composite polishing powder according to claim 1, characterized in that: The silane coupling agent used is KH-570.

3. The semiconductor double-sided polishing machine nanoscale composite polishing powder according to claim 1, characterized in that: The organic functional group is -CH3.

4. A grinding fluid, characterized in that, Includes the following ingredients by weight percentage: 50% of the nanoscale composite grinding powder according to any one of claims 1-3: The composite suspending agent comprises 48.5% of the following components: polyethylene glycol (PEG), used to adjust the viscosity of the grinding slurry to 15-25 mPa·s; sodium carboxymethyl cellulose (CMC), used to form a three-dimensional network structure and inhibit sedimentation; and sodium dodecylbenzene sulfonate (DMS), used to reduce the surface tension of the grinding slurry to 25 mN / m. The remainder is deionized water. The mass percentages of PEG, CMC, and DMS in the composite suspending agent are 40%, 15%, and 5%, respectively. Functional additives include: 0.5% nano-titanium dioxide with a particle size of 10nm, used for photocatalytic degradation of organic pollutants; and 1% biological buffer, used to stabilize the pH of the grinding slurry at 7.5±0.2.

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