Compound semiconductor micromechanical structures offer enormous potential for convergence of photonics and microelectromechanical systems (MEMS). This manuscript lays out the fundamental fabrication process principles and postfabrication processing of micromechanical structures of photonic MEMS based on InP platform. For prevention of adhesive failures in these microstructures from “in-use” stiction, hydrophobicity of microstructure surfaces is a benign property. Unlike Si which has a hydrophyllic surface, InP is fortunately relatively hydrophobic, as confirmed by contact angle measurements. However, this hydrophobicity in InP is lost in the course of processing, as confirmed by contact angle measurements and detection of hydroxyl functional groups on surface by investigations using X-ray photoelectron spectroscopy. Vapor phase surface treatment with hexamethyldisilazane helps to restore the surface hydrophobicity of InP, as evidenced in post-treatment elevated contact angles. Additionally, the microstructures have been observed to show out-of-plane deformation, which has been characterized with white light interferometry. The stress gradient has been calculated to be 16.32MPa∕μm from bending in cantilever arrays. The source of this stress gradient in InP layers was investigated through depth profiling using secondary ion mass spectrometry, which revealed arsenic gradient through the thickness of InP layers.

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