Photoforming Intricate Articles in Thickened High Definition Pho

Spring 1988

Photoforming Intricate Articles in Thickened High Definition Photoresist

The well established process of photoforming1 can be used to make metal components with intricate plan-view detail in the range of a few micrometres. Such articles include transmission electron microscope specimen grids. Fig 1. aperture discs for use in electron optics, evaporation masks2 and micro-Fresnel zone plates 5.

The ratio (thickness/resolvable line width) of features. eg bars and gaps. in photoformed articles is defined as the aspect ratioJ . Established production [echnology has been used [0 produce articles approximately 10J1m thick with an aspect ratio of approximately 1.0, eg Fig 1(c). There is. however. a requirement for components with features in the range 5 11m. or less. with an aspect ratio of about 2.0, ie a thickness of about 10Jim, tor adequate mechanical strength. There is also a requirement for thicker components, up to 50 11m. which retain as much fine detail as possible,

The present work shows that photoforming can be used to produce components from 10 10 30/lm thick with an aspect ratio of 2.0, or higher in some cases.

Dr. David Allen and P.J. Hampson, Cranfield Institute of Technology