RIE passivation layer removal by remote H-plasma and H ₂/SiH ₄ plasma processing

Remote H-plasma and H ₂/SiH ₄ plasma processes were studied as potential dry cleaning processes following reactive ion etching (RIE). The processes were compared to a process of UV/ozone followed by an HF dip. The native oxide from Si(100) substrates was removed with an RIE etch of CHF ₃/Ar. The RIE process produced approx. 150angstrom of a continuous fluorocarbon (CF _x) passivation layer on the Si surface. For the post-RIE-cleaning three approaches were studied and compared including (1) uv-ozone exposure followed by an HF dip, (2) remote H-plasma exposure, and (3) remote H ₂/SiH ₄ plasma exposure. Auger electron spectroscopy (AES) was used to investigate the surface chemical composition, and AFM was used to measure changes in surface roughness. All three processes showed substantial removal of the passivation layer. The CF _x polymer was completely removed in less than 1 min for samples exposed to a 100W remote H-plasma at 15mTorr and 450°C. With the addition of approx.0.1% of SiH ₄, the remote H ₂/SiH ₄ plasma also showed increased removal of residual oxygen contamination. The surface roughness of the plasma processed surfaces increased slightly.