What is photomask for ?
Photomask is an essential semiconductor manufacturing component that contains the detailed blue print of circuit or device design. Using the photomask, specific images of detailed device design are transferred onto the surface of semiconductor Silicon wafers by means of photolithography.
The principle of photomask is similar to photography in many ways. Photomask is used just like negatives of photography films that capture specific images which could be reproduced later.
In photography, multiple copies of photos could be reproduced using the original images captured on the negative photo films. Likewise, photomask is used just like the negatives of photographic films to produce duplicate images or patterns on to the Silicon wafers. As in the case with photography, a single photomask plate can be used to produce identical images on, thousands of wafers. As the quality of finished photographs would be determined by the quality and the properties of the original films, it is also true that the quality of the photomask will also determine the ultimate quality of semiconductor chips and LCD panels.
In other words, photomask plays the role of photographic negative film in the manufacturing of semiconductor chips or LCD panels. Quartz plates are commonly used as the choice of substrates on which detailed images or patterns are formed. The patterns or images are, then, transferred onto the wafer surfaces by shining lights through the quartz plates, just like the negative films that are used to project certain images on to the photographic papers. Since the precision and accuracy of the pattern geometry on the photomask affects device quality and the degree of device integration on the wafers, photomask is considered as a key integral part of overall semiconductor technologies.