develop

Development is the chemical process that removes soluble photoresist areas to reveal the patterned image after exposure. **Positive resist**: Developer removes exposed (soluble) areas. Pattern matches mask bright areas. **Negative resist**: Developer removes unexposed areas. Pattern is inverse of mask. **Developer chemistry**: TMAH (tetramethylammonium hydroxide) solution is standard for positive resists. 2.38% concentration common. **Mechanism**: Basic developer solution dissolves deprotected polymer (positive) or unreacted polymer (negative). **Process**: Puddle or spray developer on wafer, allow develop time (30-90 seconds typical), rinse with DI water. **Develop time**: Controls how much resist removed. Related to exposure dose. Under/over develop affects CD. **Puddle develop**: Developer puddle on wafer surface. Uniform develop across wafer. **Spray develop**: Continuous spray of fresh developer. Better uniformity for some processes. **Rinse**: DI water rinse stops development. Thorough rinse required. **Post-develop inspection**: ADI (after develop inspection) for CD, defects before etch.