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

A chemical mechanical grinding (CMG) wheel was developed for planarization of silicon wafers, which consists of magnesium oxide (MgO) abrasives and calcium carbonate (CaCO3) additives, mixed with 25 % weight percentage of magnesium chloride (MgCl2) 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.