Orthogonal Experimental Research on Dielectrophoresis Polishing (DEPP) of Silicon Wafer.

Tianchen Zhao,Kaiping Feng,Julong Yuan,Qianfa Deng,Zhaozhong Zhou,Cheng Zhang

doi:10.3390/mi11060544

Abstract

Silicon wafer with high surface quality is widely used as substrate materials in the fields of micromachines and microelectronics, so a high-efficiency and high-quality polishing method is urgently needed to meet its large demand. In this paper, a dielectrophoresis polishing (DEPP) method was proposed, which applied a non-uniform electric field to the polishing area to slow down the throw-out effect of centrifugal force, thereby achieving high-efficiency and high-quality polishing of silicon wafers. The principle of DEPP was described. Orthogonal experiments on important polishing process parameters were carried out. Contrast polishing experiments of silicon wafer were conducted. The orthogonal experimental results showed that the influence ratio of electric field intensity and rotation speed on material removal rate (MRR) and surface roughness was more than 80%. The optimal combination of process parameters was electric field intensity 450 V/mm, rotation speed 90 rpm, abrasive concentration 30 wt%, size of abrasive particle 80 nm. Contrast polishing experiments indicated that the MRR and material removal uniformity of DEPP were significantly better than traditional chemical mechanical polishing (CMP). Compared with the traditional CMP, the MRR of DEPP was increased by 17.6%, and the final surface roughness of silicon wafer reached Ra 0.31 nm. DEPP can achieve high-efficiency and high-quality processing of silicon wafer.

Highlights

Silicon has become the most mainstream basic material in micromachines, microelectronics, and microelectromechanical systems (MEMS) because of its unique physical and chemical properties and rich mineral resources [1–4]
Broer found that poor surface quality has a detrimental effect on the availability of stable equilibria of MEMS [10]
Micromachines 2020, 11, 544 i is the experiment number, w is the number of different detection points, Hij and Rij are respectively the measurement values of material removal rate (MRR) and surface roughness in the No i experiment

Summary

Introduction

Silicon has become the most mainstream basic material in micromachines, microelectronics, and microelectromechanical systems (MEMS) because of its unique physical and chemical properties and rich mineral resources (about 26% of the earth’s crust weight, second only to oxygen) [1–4]. Broer found that poor surface quality has a detrimental effect on the availability of stable equilibria of MEMS [10]. Quality is very important for silicon wafer used in micromachines. DDEEPPPP uuttiilliizzeess tthhee DDEEPP eeffffeecctt ooff aabbrraassiivveess iinn aannoonn--uunniiffoorrmmeelleeccttrriiccfifieellddttooaassssiissttppoolliisshhiinngg. AAss aa nnoovveell ppoolliisshhiinngg mmeetthhoodd,, DDEEPPPP nneeeeddss ttoo ffuurrtthheerr rreesseeaarrcchh tthhee iimmppaacctt ooff vvaarriioouuss pprroocceessss ppaarraammeetteerrss oonn ppoolliisshhiinngg rreessuullttss,, aanndd tthhrroouugghh ssyysstteemmaattiicc ppoolliisshhiinngg eexxppeerriimmeennttss ttoo ddeetteerrmmiinnee aanndd ooppttiimmiizzeeDDEEPPPPpprroocceessssppaarraammeetteerrss. ABsaesdedoonnththeepprirninccipipleleaannddmmeecchhaanniissmmooff DDEEPPPP,,tthhee mmoosstt iimmppoorrttaanntt pprroocceessss ppaarraammeetteerrss tthhaatt aaffffeecctt tthhee ssuurrffaaccee rroouugghhnneessss aanndd MMRRRR ooff DDEEPPPP aarree eelleeccttrriicc fifieelldd iinntteennssiittyy,, aabbrraassiivvee ccoonncceennttrraattiioonn,,ssiizzeeooffaabbrraassiivveeppaarrttiiccllee,,aannddrroottaattiioonnssppeeeeddooffppoolilsishhininggpplalatete. The last two columns in45t0he table are the M9R0R and the final sur3f0ace roughness, respect1iv10ely, which are the indexes examined of the experiment. A total of 13 points need to be measured on each silicon wafer surface.

Results and Discussion

Contrast Experiment of Polishing

CMP Method