Papers by Author: Sumio Kamiya

Abstract: In recent semiconductor industry, production of ever flatter, thinner and larger Si wafer are required to fulfill the demands in high integration and cost reduction. A severe problem encountered in wafer thinning process is the warp and distortion of wafer induced by the residual stress and subsurface damage. Chemo-mechanical grinding (CMG) process is emerging process which combines the advantages of fixed abrasive machining and chemical mechanical polishing (CMP), offers a potential alternative for stress relief. This paper studies the influence of the wheel manufacturing process on the wheel physical properties. Three-factor two-level full factorial designs of experiment are employed to reveal the main effects and interacted effects of mixing method and filtration of raw materials on the bending strength and elastic modulus of CMG wheel. The difference in wheel properties is discussed by association with CMG performance including wheel wear, grinding force and surface roughness.

Abstract: Chemo-mechanical grinding (CMG) process is a promising process for large-sized Si substrate fabrication at low cost. An encountered issue in current CMG process of Silicon (Si) wafers is metallic contaminations on ground Si wafer surface, which is attributed to the existence of sodium carbonate in wheel compounds. In this paper, four different CMG wheels were developed and grinding experiments were conducted to study the effects of exclusion of sodium carbonate and concentration of ceria abrasive on grinding performance. The grinding characteristics of the four wheels were analysized and discussed to reveal the effects of different compositions.

Abstract: Silicon wafer thinning process is meeting great challenges to fulfill requirements of ultra-thin IGBT for automotive applications. Chemo-mechanical grinding (CMG) process is potentially emerging stress relief thinning process which combines the advantages of fixed abrasive machining and chemical mechanical polishing (CMP). A major issue in CMG of Si wafers is the relatively low material removal rate (MRR). This paper studies the influence of the wheel specifications and grinding conditions on the MRR of CMG. Two sets of three-factor two-level full factorial designs of experiment (DOE)[1] are employed to reveal the main effects and interacted effects of CMG wheel specifications and grinding parameters on MRR. The optimal combination scenarios for improving MRR of CMG are analysized and obtained. By use of the optimal CMG wheel and grinding parameters, the MRR of more than 60nm/min is achieved.

Abstract: The single crystal of Si is still one of the most important candidates among other materials including Single crystals of SiC, GaN, C(diamond) or compound semiconductors. The innovative process as called CMG(Chemo-Mechanical-Grinding) for Si wafer has been recently developed which is different from conventional CMP(Chemo-Mechanical-Polishing ) process. The CMG process can be done under dry conditions using CeO2 based solid bulk abrasives. The microstructures for surface and subsurface of Si single crystal after CMG process were analyzed using TEM/EDX, AFM, MFP-3D Microscope. The mechanism of CMG process was also investigated by X-ray diffraction and ICP chemical analysis using products by chemical reaction between Si and CeO2 abrasives. The results showed that Si single crystal after CMG had, 1) no defects even Si lattice revel or mechanical imperfections,2) better surface roughness as compared to CMP process. The CMG mechanism concluded that CeO2 reacted with Si producing Ce-Si-O amorphous phase.