KINETICS OF BORON ATOMS IN AR-BCL3 FLOWING MICROWAVE DISCHARGES

Production of boron atoms has been investigated in Ar-BCl3 flowing mic rowave discharges (2450 MHz) for two different configurations at 700 P a. In the first one, an Ar-1.5% BCl3 gas mixture is introduced in the discharge condition, while the same gas mixture is introduced downstre am of a pure argon plasma in the second one. Optical emission spectros copy (OES) has been used to follow the spatial variations of line and band intensities for various excited species (Ar, B, B+, B-2, BO, Si, Cl and BCl). Variations of electron density along the plasma column, d educed from OES observations, are attributed to electron attachment re actions involving boron trichloride. Excitation processes leading to f ormation of excited species are discussed by analysing the OES results acquired in the two discharge configurations. For B, B+, B-2 and BCl species, excitation proceeds from electronic collisions with ground st ates, whereas a complex kinetic process is found for chlorine atom exc itation. It is also shown that information on boron atoms could be gai ned by using the chemiluminescent reaction produced between boron atom s and molecular oxygen. A boron atom lifetime of about 10(-3) s is obt ained by introducing an Ar-O-2 gas mixture in Ar-BCl3 post-discharges.