23.3.3. DRIE of Glasses

Silica (pure SiO2) and glass (SiO2 mixed with other metal oxides) are used as substrates when optical transparency, electrical insulation, low thermal conduction, and/or biocompatibility are required. Silica and glass also overcome many limitations of polymers because of their low auto-fluorescence, mechanical wear resistance, reusability, and smooth surfaces.

Plasma etching of glass requires ions with high energy and high directionality because the oxide bonds are strong. C4F8, C2F6, and CHF3 are used as etch gases because they exhibit high selectivity with standard masking materials [28, 29]. Alternatively CF4 or SF6 can be used [30–32], but silicon masking does not provide good selectivity. The glass horizontal surface ...

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