Time dependent effects in photoresist outgassing

Ion implantation into photoresist wafers gives rise to large quantities of photoresist outgassing. The purpose of this undertaking was to determine the time dependence of the outgassing rate. Photoresist wafers begin outgassing when implantation begins, but how fast does the outgassing rate decay once a wafer passes the implanting beam? This question is relevant for designing implanter process chambers with rotating disks. The photoresist outgassing decay rate determines the geometry of the gas load, and can be used to determine pump placement and chamber design. The data indicate that an implant of 50 keV boron results in an outgassing rate that depends on time as t/sup -0.8/ where t is the time since a wafer was last implanted.