#photolithography

I spent part of the day today spinning photoresist. Photoresists are light sensitive chemicals used in photolithography. They are spun onto the sample at high speeds, using a tool like the one in the picture, to ensure an even coat. Yellow lighting is used in rooms dedicated to resist application and processing to prevent it from getting exposed. Once the resist is applied, a pattern can be transferred to your sample by exposing only certain areas to light.

Patterned silicon wafers in the clean room.

Photolithography is a technique similar to photography used to make very small micron (~0.00004 inch) sized features.  Wafers are coated in light sensitive chemicals called photoresist and then certain areas are exposed to light to create a pattern. The processing room is lit with yellow light to avoid exposing the resist. Photolithography is commonly used to make integrated circuits in electronics, but it is also used in basic research in fields such as physics, material science, engineering, and even biology.