Improved adhesion between C-MEMS and substrate by micromechanical interlocking

This paper describes a new method to improve adhesion between high-aspect-ratio carbon micro/nano-structure and silicon substrate by micromechanical interlocking over conventional carbon micro-elecro-mechanical system (C-MEMS) process. Anisotropic wet chemical etching using potassium hydroxide (KOH) solution and aqueous tetramethyl ammonium hydroxide (TMAH) is applied to form various aspect-ratio and spacing pits in silicon substrate with and without a thin film layer of silicon dioxide, respectively. Great improvement on adhesion is demonstrated that the photoresist structure is found to remain robustly attached to substrate during the process of prolonged SU-8 photoresist development and immersion in heated 40% potassium hydroxide at 80degC. Furthermore, carbon MEMS after pyrolysis process is well bonded to silicon substrate without peeling off and high-aspect-ratio glassy-carbon MEMS remain upright.