Photomasks are used to replicate their structure onto a light sensitive substrate, e.g. a wafer. This process is widely used in the electronics or micro device industry and has evolved over the years. There are two basic methods, one is when the mask is brought into contact or close contact (proximity) with a wafer. The mask is printed on a 1:1 scale. These systems are called "mask-aligners" and they are widely used for applications requiring 1-micron or more resolution.
The other method is to project the mask trough an optical system onto a wafer. A contact free exposure and the possibility of a size reduction are the main advantages.
Photomasks play a major role in enabling ever smaller structures and features in modern semiconductor electronics like DRAM technology. A $2 billion market is driving the development of new technologies, exposure equipment and mask technologies for the mainstream market. But these developments are hardly applied in emerging fields like micro-optics, micro-fluidics or large device (e.g. LCD display) development.
For those technologies, direct printing on mask aligners or 1:1 projection seems to be the most convenient way for pattern transfers.
