Investigating the influence of fabrication process and crystal orientationon shear strength of silicon microcomponents

A summary of the influence of microfabrication processes (wet and dry etchi ng) and crystal orientation on the effective shear strength of microridges is addressed in this paper. Test results indicate that both crystal orienta tion and geometry plays an important role in determining the strength. The largest shear strengths obtained were for triangular and rectangular ridges fabricated with wet etching and deep RIE respectively. Both of these struc tures had similar crystal orientations. These strength values were approxim ately 3.5 times larger than the lowest strengths measured for wet etching s tructures. Using Chlorine RIE, we were able to demonstrate the influence of crystal orientation on strength, with microridges of {110} sidewall made o n a (100) wafer the largest. For wet etching, we found that the strength wa s concentration dependent. For example, a 45% KOH fabricated structure prod uced strength values 65% higher than 30% KOH fabricated ones (note crystal orientation the same). This was attributed to a geometric effect, that is t he 45% KOH solution had a "V" shaped bottom while the 30% KOH had a flat bo ttom. EDP and TMAH values had similar strengths to the 30% KOH solution (no te similar crystal orientation). Therefore, microcomponent strength is stro ngly dependent upon fabrication process as well as crystal orientation. (C) 2000 Kluwer Academic Publishers.