Micro-etching technology of high aspect ratio frameworks for electronic devices

High aspect ratio glass frameworks for spacer applications in the vacuum electronic devices were fabricated by photolithography. The material for the framework was photoetchable glass which has good mechanical and electrical insulating properties. The photoetchable glass was exposed to ultraviolet light, with a wave length of 312 nm, through a chrome mask. After heat treatment, the glass was etched in 10% hydrofluoric acid using ultrasonic agitation. The final dimensions of the glass framework were greatly dependent on the mask patterns and ultraviolet light exposure conditions. The framework surface was affected by the tilting of the glass surface with respect to the ultraviolet light source during the exposure process. In this work, glass frameworks, having a surface step of about 300 μm, were obtained by tilting 11°. An aspect ratio of 30 was obtained using photoetchable glass of 1000 μm thickness.