New very high frequency plasma source using a TM01-mode patch antenna withshort pins

We evaluated the basic characteristics of a new very high frequency (VHF) p lasma source using a TM01-mode patch antenna with short pins. The antenna c omprises a round dielectric plate and a round metal plate which is grounded by short pins isotropically arranged. Electromagnetic field simulation has verified the isotropic distribution of both electric and magnetic fields. Ion-saturated current density measurements (Cl-2 = 100 seem, 1 Pa and VHF p ower = 1000 W) by placing the antenna in a cylindrical etching chamber 450 mm in diameter and 217 mm deep have revealed that uniform plasma is generat ed if a circular slit is positioned properly; that higher ion density is at tained with dielectric plate relative permittivity set at 20, than at 7; an d that increased VHF power causes proportional increase in ion density with out giving rise to mode jumping or hysteresis. Experiment has revealed that the plasma source subject to our study provides superior ignitability, bei ng capable of starting discharge even under 0.1 Pa. Experimental etching of polycrystalline silicon using this plasma source has yielded satisfactory results that etch rate is 183.5 nm/ min+/-3.68%, poly-Si selectivity agains t resist is 4.8, and that against oxide film is 280 in main etching. (C) 20 00 American Vacuum Society. [S0734-2101(00)02006-6].