post-exposure bake (peb)

Post-Exposure Bake (PEB) is a heating step after lithography exposure that completes chemical reactions in chemically amplified resists. **Purpose**: In chemically amplified resists, PEB drives acid-catalyzed reactions that change solubility. Completes exposure effect. **Temperature**: Typically 90-130 degrees C. Critical parameter. **Time**: 60-90 seconds typical. Must be uniform. **Chemical amplification**: Photoacid generated during exposure catalyzes polymer deblocking during PEB. Amplifies exposure signal. **CD sensitivity**: CD is very sensitive to PEB temperature. Tight control required. **Acid diffusion**: During PEB, acid diffuses through resist. Affects resolution and line edge roughness. **Cross-wafer uniformity**: Hot plate uniformity directly impacts CD uniformity. **Delay effects**: Time between exposure and PEB must be controlled. Some resists sensitive to delay. **Track integration**: PEB performed in lithography track, immediately after exposure. **Temperature accuracy**: +/- 0.1 C or better specification. **Troubleshooting**: CD shifts often traced to PEB issues.