Prebake (Soft bake): After spinning the photo resist still contains solvents up to 15% and there could be built in stresses. The wafers are prebaked at ~80°C for about 20 minutes to densify the resist and remove the stress. The thickness of the resist is usually decreased by ~25% after this step. The prebake also promotes the adhesion of resist to wafer. Less prebake can increase the development time (rate).

Alignment and exposure:

Let us say that already there is a pattern available on the wafer and the new mask is to be aligned with respect to this pattern. Usually with each mask alignment markers as shown in figure will be available this marks will greatly help operator to align. Usually three degrees of freedom is available on the alignment bench to achieve proper alignment.