HW_2 - ECE 432 Introduction to MEMS Homework 2(Due in class...

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ECE 432 Introduction to MEMS Sunil Bhave Homework 2 (Due in class on Monday, 9/10/2007) Fall 2007 1. Silicon Crystal a. Show that the angles between the {110} and {111} planes of a silicon (100) wafer are 35.26, 90 and 144.74º b. With KOH, the etch selectivity between the {100} and {111} planes is 400:1, not infinite.Therefore, the sidewalls of a pit etched in a (100) wafer will be very close to the {111} planes but not exactly parallel to them. (a) What angle do they really make? (b) What etch ratio would be needed to make 45° sidewalls? 2. Deep Reactive Ion Etching (DRIE) Explain what you see in the scanning electron micrographs (SEMs) below and why these effects occur: 3. Bulk Etching The Si {100} wafer shown below has a patterned silicon nitride mask on its top surface, and an unpatterned nitride layer on the bottom surface. With TMAH, the etch selectivity between the {100} and {111} planes is 35:1, and the {100} etch rate is 1 μm/min. Assuming that the nitride layer and all other Si crystal planes are not etched, sketch the
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This homework help was uploaded on 02/22/2008 for the course ECE 4320 taught by Professor Bhave during the Fall '07 term at Cornell.

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HW_2 - ECE 432 Introduction to MEMS Homework 2(Due in class...

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