As of 8/1/23, this furnace is shut down and will be permanently removed from the cleanroom. It will be replaced by a new Tystar furnace in March 2024. Find the current project schedule and more information here.
Silicon dioxide (SiO2) is deposited at between 300 and 450C (depending on needs... ie metals 300C), low pressure (~350 mtorr), from silane and oxygen with or without phosphine doping. Doped LTO is also called PSG, or phosphosilicate glass). The refractive index of the film depends on the phosphorous content, lower deposition rate. The refractive index is also influenced by the temperature of the deposition. The oxide deposition rate is mostly dependent on the temperature and is ~ 175A/min at 400C for 4 inch wafers (~200A/min for 3 inch wafers).