导体镶嵌型巨电流变抛光液及其对硅材料的抛光

邱昭晖, 江波, 陆坤权, 沈容, 熊小敏

表面技术 ›› 2023, Vol. 52 ›› Issue (5) : 218-225.

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表面技术 ›› 2023, Vol. 52 ›› Issue (5) : 218-225. DOI: 10.16490/j.cnki.issn.1001-3660.2023.05.021
精密与超精密加工

导体镶嵌型巨电流变抛光液及其对硅材料的抛光

  • 邱昭晖1, 熊小敏1, 江波2, 陆坤权3, 沈容3
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Nano-conductor Dominated Giant Electrorheological Polishing Fluid and Its Application to Silicon Materials

  • QIU Zhao-hui1, XIONG Xiao-min1, JIANG Bo2, LU Kun-quan3, SHEN Rong3
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摘要

目的 解决现有电流变抛光液在电场下强度低和使用寿命短等问题。方法 分析现有电流变抛光液的缺点及其原因,提出将新型巨电流变液——导体镶嵌型电流变液应用于抛光领域,并研制出以二氧化硅为磨料,以镶嵌了纳米碳的二氧化钛为电介质颗粒的硅油基电流变抛光液。测定添加了不同粒径磨料抛光液的剪切强度与电场强度、温度、使用时间的关系。搭建简易的旋转式电流变抛光装置,对不同粒径磨料的电流变抛光液在硅片表面的抛光效果进行试验。结果 碳镶嵌二氧化钛基电流变抛光液具有高剪切强度(>30 kPa)、低漏电流(<1 μA)、高温度稳定性(25~125 ℃)、长使用寿命和对少量磨料不敏感等优点。抛光实验结果表明,在电压2.5 kV下,硅片经过添加了2 μm磨料的电流变抛光液持续抛光3 h后,其表面粗糙度从206 nm降至6.4 nm。之后再采用添加200 nm磨料和20 nm磨料的抛光液先后继续精抛后,其粗糙度降至0.46 nm和0.36 nm。结论 碳镶嵌二氧化钛基巨电流变抛光液能有效降低表面粗糙度,改善表面质量,很好地应用于精密抛光领域,展示出良好的应用前景。

Abstract

The work aims to overcome the limitations of low intensity and short lifetime of existing electroheological (ER) polishing fluid under the electric field. The defects of the existing ER polishing fluid were analyzed to remedy them by putting forward the idea of applying a novel giant ER fluid based on dielectric particles inlaid with conductor clusters to the polishing field. The novel giant ER fluid consisted of dielectric particles inlaid with nano-conductor clusters and isolating oil, the effect of which was the result of the strong interaction generated by the conductor nanoclusters in the process of inducing dipole moments in the electric field. Due to the stable combination of dielectric particles and conductor nanoclusters, the fluid could withstand the long-lasting friction and temperature changes. Therefore, its advantages of larger shear strength and long lifetime, made it suitable for being an ER polishing fluid. This research developed a silicon-oil based ER polishing fluid using TiO2 inlaid with nano-carbon as dielectric particles and SiO2 as abrasive. The basic principle of the ER polishing was that the ER particles in the fluid formed a chain or column structure under the influence of electric field, enveloping abrasive particles and becoming a flexible polishing head. When the head moved, the abrasive exerted a micro cutting effect on the surface of workpiece so as to achieve the purpose of polishing. During the study, the dissertation determined the relationships between the shear strength of polishing fluid added with abrasives of different particle sizes (2 μm, 200 nm, 20 nm) and electric field that was under different strength and temperatures. A simple rotary electrostatic polishing device was set up to carry out trials on the polishing effect of ER fluids with abrasives of different particle sizes. The electrodes were made up of two paralleled copper sheets which were 3 mm thick and 10 mm in both length and width. The gap between the electrodes was 1 mm wide. By applying a high voltage on the copper sheets, the shear strength of ER polishing fluid which was between and at the top of the copper sheets increased and would form a flexible polishing head. When the tool rotated, the head performed the polishing work on the workpiece. During the polishing process, the gap between the copper electrode and workpiece was 0.3 mm in width and the voltage between electrodes was 2.5 kV. The study showed that the newly developed ER polishing fluid had advantages such as high shear strength (>30 kPa), small leakage current (<1 μA), stability under high temperature (25-125 ℃), a long service life and insensitivity to small amounts of abrasives. The polishing experiment result revealed that the roughness of the silicon wafer dropped from 206 nm to 6.4 nm after being ground by the ER polishing fluid added with a 2 μm abrasive. The roughness of the silicon wafer then dropped to 0.46 nm after being polished by the fluid with a 200 nm abrasive while the roughness dropped to 0.36 nm after being polished by the fluid with a 20 nm abrasive. It is shown in this thesis that the new novel giant ER fluid can effectively reduce the surface thickness, improve the surface quality, and can be well applied to precision polishing, showing a good application prospect.

关键词

导体镶嵌型电流变液;剪切强度;电流变抛光;硅片;表面粗糙度

Key words

nano-conductor dominated electrorheological fluid; shear strength; electrorheological polishing; silicon wafer; surface roughness

引用本文

导出引用
邱昭晖, 江波, 陆坤权, 沈容, 熊小敏. 导体镶嵌型巨电流变抛光液及其对硅材料的抛光[J]. 表面技术. 2023, 52(5): 218-225
QIU Zhao-hui, JIANG Bo, LU Kun-quan, SHEN Rong, XIONG Xiao-min. Nano-conductor Dominated Giant Electrorheological Polishing Fluid and Its Application to Silicon Materials[J]. Surface Technology. 2023, 52(5): 218-225

基金

国家自然科学基金(11874430)

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