Figure 4From: Nanofabrication on monocrystalline silicon through friction-induced selective etching of Si3N4 maskCorrelation of crack formation and selective etching of Si 3 N 4 mask. (a) Scratching under normal load Fn = 2.5, 3, 4 and 5 mN. (b) Crack formation after HF etching for 20 min. (c) Further etching in HF solution for 10 min and KOH solution for 35 min.Back to article page