What is Photolithography?
Many steps in the device fabrication process are intended to impact only certain areas of the wafer. To define the desired areas on the wafer (and block the remaining areas) a series of masking layers are used. This allows us to transfer shapes that are created using CAD software onto the surface of the wafer with sub-micron resolution. The process of photolithography involves the use of a material called photoresist to generate a specific pattern on the surface of the wafer. Photolithography is useful because it can transfer the pattern to the wafer surface very quickly. Photoresist is a light-sensitive material which can be processed into a specific pattern after being exposed to light energy in the shape of the desired pattern. The process is somewhat similar to photography where light energy forms a pattern on the film. Once the photoresist has been developed, only certain areas of the wafer are covered with photoresist. The subsequent process steps will only affect the areas where
