CF4 RIE Pre-Etch During Etchback of Sidewall Formation
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
In the manufacture of semiconductor devices sidewall uniformity is desirable. During the RIE (reactive ion etch) step, polymer formation can produce non-uniformities. This article suggests the use of a RIE pre-etch to improve etchback uniformity. In sidewall formation processing, a RIE etchback in CHF3/Ar takes place with etch uniformity varying as much as 13%. Even though CHF3/Ar is valued for a high etch ratio of oxide to nitride during RIE, a prolonged etch is undesirable. This is because the prolonged etch may produce non-uniformities within a wafer and within a wafer batch. Sidewall uniformity is essential to control and to insure reproducibility of electrical parameters BVebo and BVces . There is also a lengthening of turnaround time since the tool must be cleaned of polymer formed when processing each run in CHF3/Ar.