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written 8.3 years ago by gravatar for hetalgosavi hetalgosavi • 1.7k modified 8.3 years ago by gravatar for juilee juilee • 100

Mumbai University > Electronics Engineering > Sem 8 > MEMS Technology

Marks: 5M
mems technology
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written 8.3 years ago by gravatar for hetalgosavi hetalgosavi • 1.7k
  • Recent developments have substantially improved the performance of DRIE with better sidewall protecting matrials.
  • Silicon substracts with A/P over 100 was with θ = ±20 at a depth of up to 300 µm was achieved. The etching rate, however was reduced to 2-3 µm/min.

Popular sidewall protecting materials:

Sidewall protection materials Selectivity ratio Aspect ratio A/P
Polymer   30:1
Photoresists 50:1 100:1
Silicon dioxide 120:1 200:1

Wet Vs. Dry Etching

Parameters Dry etching Wet etching
Directionality Good for most materials Only with single crystal materials (aspect ratio up to 100)
Production-automation Good Poor
Environmental impact Low High
Masking film adherence Not as critical Very critical
Selectivity Poor Very good
Materials to be etched Only certain materials All
Process scale up Difficult Easy
Cleanliness Conditionally clean Good to very good
Critical dimensional control Very good (< 0.1µm) Poor
Equipment cost Expensive Less expensive
Typical etch rate Slow (0.1 µm/min) to fast (6µm/min) Fast (1µm/min and up)
Operational parameters Many Few
Control of each rate Good in case of slow etch Difficult
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