DIAGNOSTIC OF AR-BCL3 MICROWAVE DISCHARGES BY OPTICAL-EMISSION SPECTROSCOPY

In this report, Ar-BCl3 plasmas produced by a 2450 MHz microwave disch arge at 700 Pa are investigated by means of optical emission spectrosc opy (OES). The emission spectrum of such discharges with high dilution of BCl3 in argon is very rich in atomic lines (Ar, Cl, B+, Si) and mo lecular bands (BCl, B-2, BO). The recently identified (1) (1) Delta(u) --> b (1) Delta(g) and (2) (3) Pi(g)-->A (2) Pi(u) systems of B, are observed and two new transitions are attributed to this latter system. Weak BO bands corresponding to the A(2) Pi-->X-2 Sigma(+) transition are also observed. The excitation channels leading to the formation of these species are analysed by using data obtained by OES. Electron at tachment reactions involving BCl3 are found to be important in the kin etics of the microwave discharge, whereas reactions arising from metas table argon energy transfer must be negligible. Spatial analysis of th e microwave discharge by OES is also presented and processes leading t o excited B-2 states are discussed. Etching reactions are important th rough the observation of both Si and BO excited states at the end of t he discharge. (C) 1997 Elsevier Science S.A.