ION-ASSISTED ETCHING OF SI WITH CL2 - THE EFFECT OF FLUX RATIO

The room-temperature ion-assisted etching of poly-Si with molecular ch lorine and 1 keV Ar+ ions has been studied for a wide range of the neu tral flux/ion flux ratio. In situ measurements of the etch rate made u sing quartz crystal microbalance methods are combined with modulated b eam mass spectrometric studies of the etch products and the unreacted molecular chlorine reflected from the Si surface. The reaction probabi lity for the incident chlorine is determined in two independent ways a nd good agreement is obtained. The products are determined to be prima rily SiCl2 and SiCl4 with significant amounts of sputtered SiCl at low flux ratios.