1.0 The angle between the {100} and {111} crystal planes in a silicon wafer is 54.74 degrees, but...2.0 Draw a cross-section of the following process flow. Assume a bare {100} silicon starting subs...3.0 Draw a cross-section of the same process as in question 2, but assume that positive resist is...4.0 Draw a cross-section of the same process as in question 2, but use a plasma oxide etch and a ...5.0 Draw a cross-section of the following process flow. Assume a bare {100} silicon starting subs...6.0 A (100) wafer with a nitride mask with the following openings is etched in a KOH solution wit...EE245 Homework 2 September 21, 1999 1EE245 Homework 2Due Tuesday 10/27/991.0 The angle between the {100} and {111} crystal planes in a silicon wafer is 54.74 degrees, but a real etchant will not give perfect anisotropy. Calculate the actual angle of the sidewall of a pit etched with KOH (assume anisotropy 400) and EDP (assume anisotropy 20).2.0 Draw a cross-section of the following process flow. Assume a bare {100} silicon starting substrate. If I release this cantilever, how will it curl?1. LPCVD PSG, 2micron2. spin negative resist, expose using mask1, develop3. timed HF etch with 50% overetch (how long will this take?)4. strip resist in acetone5. LPCVD polysilicon, 2 microns, anneal at 900 C for 30 minutes6. spin positive resist, expose using mask 2, develop7. plasma poly etch, 50% overetch (what machine should I use? how long will this take?)3.0 Draw a cross-section of the same process as in question 2, but assume that positive resist is used for both lithography steps.4.0 Draw a cross-section of the same process as in question 2, but use a plasma oxide etch and a wet silicon etch. Compare the cross-sections. How mask2mask14 micronsEE245 Homework 2 September 21, 1999 2does plasma etching affect the minimum line and space that I can use in a process?5.0 Draw a cross-section of the following process flow. Assume a bare {100} silicon starting substrate.1. LPCVD oxide, 2micron2. LPCVD polysilicon/mask1 (this is short-hand for spin, expose, develop, etch, and strip)3. anneal at 1000C for 30 minutes4. 10 minute HF etch5. thermal oxidation, 0.1 microns, dry O2 (how long will this take?)6. LPCVD polysilicon/mask26.0 A (100) wafer with a nitride mask with the following openings is etched in a KOH solution with an etch rate of 1 micron/minute, and a selectivity of 400. Draw the cross-section after 10 minutes and 100 minutes of etching.How will the cross-sections change if we use EDP instead of KOH?5
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