Surface integrity and removal mechanism of chemical mechanical grinding of silicon wafers using a newly developed wheel

Abstract

A chemical mechanical grinding (CMG) wheel was developed for planarization of silicon wafers, which consists of magnesium oxide (MgO) abrasives and calcium carbonate (CaCO 3 ) additives, mixed with 25 % weight percentage of magnesium chloride (MgCl 2 ) solution. It was shown that chemical reactions occurred during the grinding process, which formed a softened layer on the top of silicon substrate. The reactants could be much more easily removed by mechanical abrasion than the removal of Si phase itself. The newly developed wheel was able to produce a similar surface integrity to that obtained from chemical mechanical polishing (CMP), i.e., the CMG achieved a surface roughness of 0.5 nm in R a and a subsurface damage layer of 13 nm thick. The CMG process developed thus has great potential for back grinding or thinning of silicon wafers in order to replace CMP.

Mechanism analysis and modelling of surface roughness for CeO2 slurry assisted grinding of BK7 optics considering both particle size and mass fraction

“…It was found that there is still grinding traces on the surface of nano grinding, but the surface of CMG is smooth without grinding traces and surface damage. Dong et al [31] used a CMG wheel of magnesium oxide (MgO) abrasives to grind silicon wafers.…”