cantilevers to the sloped <111> sidewall, the wet wafers will be gently sprayed with isopropyl acohol. The alcohol will then be allowed to dry in the air PRE-LAB QUESTIONS 1. What chemical is used to etch the silicon? Is this an isotropic or anisotropic etch? 2. Given that the density of water is l gram/ml, how much KOH should be mixed with 3 liters of de-ionized water to create a 20% by weight solution? 3. Referring to Figure 2.1, what is the KOh etch rate in the <100> direction for the given process parameters? 4. Using the mask shown below,( Figure 2.2), sketch how the cross-sections A-A and B-B would look after Step 2.1 <100> silicon etch rotes in [um/h)for various KOH concentrations and etch temperatures as calculated from Eq [A-1]by setting E。=0.595 ev and k。=2480μmh·(mol)-423 Temperature ['cI %KoH"203040506070°80°90100 10 1.493.26.713.32524682140233 151.56347.014.026.54986147245 20 157347.11402674986148246 1533369136259478 144239 144316.51282444579135225 35 132295911.82234172124206 1172.55.310.51993664110184 45050 101224.69017.1315595158 08418387.51422646 79131 066143059112213662104 0.50 22448415274778 Reference: H. Seidel et al., ""Anisotropic Etching of Crystalline Silicon in Alkaline Solutions, J Electrochem.Soc,137(11)3612-32,1990 Figure 2.1 2 of 3cantilevers to the sloped <111> sidewall, the wet wafers will be gently sprayed with isopropyl acohol. The alcohol will then be allowed to dry in the air. PRE-LAB QUESTIONS: 1. What chemical is used to etch the silicon? Is this an isotropic or anisotropic etch? 2. Given that the density of water is 1 gram/ml, how much KOH should be mixed with 3 liters of de-ionized water to create a 20% by weight solution? 3. Referring to Figure 2.1, what is the KOH etch rate in the <100> direction for the given process parameters? 4. Using the mask shown below, (Figure 2.2), sketch how the cross-sections A-A and B-B would look after Step 2.1. Reference: H. Seidel et al., “Anisotropic Etching of Crystalline Silicon in Alkaline Solutions”, J. Electrochem. Soc., 137(11):3612-32, 1990. Figure 2.1 Page 2 of 3