Anisotropic Crystallographic Wet Chemical Etching of Silicon KOH

A number of commonly used masking layers are listed in Table 2.3. 

Waiting for the natural etch stop means that L , T or U -shaped V-troughs necessary for microreactors cannot be produced. To produce these troughs, therefore, etching is interrupted when the desired depth has been reached. These V-cross-sectional troughs have convex 90° comers at any bends, and at these points there is considerable undercutting of the mask. The remedy is the corner compensation. Sacrificial surfaces are created at the convex corners, calculated in such a way that the etch time in the direction of the convex 90° comer will produce the correct shape. 

2) isotropic wet chemical etching of silicon (HE + HNO3 + CH3COOH + H2O)  

3) isotropic dry chemical etching of silicon (reactive ion etching RIE)  

5) anisotropic dry etching with inductively coupled plasma for silicon and glass, the maximum for glass is 40-50 [xm, problem is the small etching rate [5]. 

---