EFFECTS OF POSTETCHING TREATMENTS ON ELECTRICAL CHARACTERISTICS OF THERMAL OXIDES ON REACTIVE-ION-ETCHED SILICON SUBSTRATES

Thin oxides thermally grown on the reactive-ion-etched (RIE) silicon substrates in N2O and diluted O-2 ambients have been studied. The RIE will strongly affect the silicon surface microroughness and lead to poor oxides properties. Using the after-treatment-chamber (ATC) process, CF4 addition in the O-2 plasma can further improve the time-zero-to-dielectric-breakdown (TZDB) characteristics of the thin oxides as compared with pure O-2 plasma. This is because CF4 addition in the ATC can remove the damaged silicon layer and smooth the silicon surface since the (O)2 plasma can effectively only strip the polymeric layer. In addition, the N2O-grown oxides can enlarge the process window of the CF4/O-2 ATC treatments with respect to pure oxides.