Microfabrication technologies

4.1

Discuss the effect of plasma parameters in a dry etching equipment on the etch results. Consider parameters such as gas composition, C/F ratio, bias power, etc.

4.2

Deep reactive ion etching (DRIE) is an important fabrication step for silicon etching. Why is that? One particular version is the so-called Bosch process? How does it work? Discuss the gases used, their purpose, and the scalloping effect.

4.3

Compare and contrast wet etching and dry etching techniques used in semiconductor fabrication (etch mechanism and rate, isotropy versus anisotropy, etch selectivity, precision, material compatibility, etc.).

4.4

Why is isotropic etching important in MEMS? Discuss the etch mechanism of the isotropic etching of silicon in an HNA bath.

4.5

How does anisotropic etching differ from isotropic etching? Discuss the etch mechanism of KOH etching of silicon. Why are some crystal planes less (or quasi not) etched?

4.6

What is an etch stop in silicon microfabrication? For what important device is it used? Compare boron implantation etch stops and electrochemical etch stops