A series of controlled experiments were performed to achieve sub-1% total thickness variation across 300 mm silicon wafers using a Cee® 300X (Apogee™) spin coater platform.
Multiple process variables were evaluated, including dispense method (static vs dynamic), ramp-to-spin rates, exhaust control, pre-wet conditions, and spread spin behavior. The results identified exhaust control and ramp-to-spin as the most significant contributors to coating uniformity.
For Shipley 1813 photoresist, an optimized process using static dispense, 1750 rpm spin speed, and a ramp rate of 1750 rpm/s achieved an average thickness of 1.28 µm with a total thickness variation of 0.61%. :contentReference[oaicite:0]{index=0}
For AZ4620 thick photoresist, a multi-step process including static dispense, 500 rpm spread spin, and 2000 rpm final spin resulted in an average thickness of 9.11 µm with 0.63% total thickness variation. :contentReference[oaicite:1]{index=1}
SU-8 3025 processing utilized a static dispense followed by spread and final spin steps, producing thick films with an average thickness of 39.49 µm and a total thickness variation of 1.81%. :contentReference[oaicite:2]{index=2}
For AZ5214 image reversal photoresist, a similar structured process with static dispense, spread spin, and final spin achieved an average thickness of 1.64 µm with 0.84% total thickness variation. :contentReference[oaicite:3]{index=3}
Across all materials tested, sealing the process bowl to maintain a solvent-rich environment significantly improved coating uniformity by reducing premature solvent evaporation.
These results demonstrate that with proper optimization of dispense strategy, exhaust control, and spin profiles, sub-1% coating uniformity is achievable across a wide range of materials and film thicknesses on 300 mm substrates.
