Mechanical strengthening of Si cantilevers by chemical wet etching

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Improvement of the mechanical strength of Si structures by applying chemical wet etching was investigated. The cantilever specimens that have a sidewall surface of Si{110} were produced by a Bosch process with a resist mask. The typical height and pitch of the scalloping formed on the sidewall were 245 and 891 nm, respectively. To improve mechanical strength of the cantilever, 50 % KOH (40 °C) chemical wet etching was applied to reduce the scalloping. The cantilevers with and without chemical etching applied were bent laterally by using a manipulator under an optical microscope. The maximum stresses in the cantilever at the fracture were increased by applying chemical etching. The increment ratio of the stress in Si{110} specimens was 1.7–1.8 times. Cantilevers with and without chemical etching applied showed no big differences in terms of the fracture configurations.