Etching semiconductor materials in low-pressure RF discharge

Summary form only given, as follows. Low-pressure RF discharge (p=0.01-1 Torr) in CF/sub 4/, CCl/sub 4/ and SF/sub 6/ is widely applied for etching technological materials. This paper has discovered a link between the pressure range optimal for etching semiconductor materials and the corresponding part of the RF discharge breakdown curve in technology-relevant gases. The discharge has been ignited between plane stainless steel electrodes of 100 mm in diameter. In the pressure range p to the left of the breakdown curve minimum a polymer film grows on substrates, electrodes and discharge vessel´s walls in the process of RF discharge burning, its rate of growth decreasing with the increase of pressure. The polymer film formed is rather resistant to the action of plasma components and acids and it is weakly soluble in alkalis. Obviously, one should not use this pressure range for etching silicon. With pressure increasing, the breakdown curve starting from the minimum passes through the inflection point. It is expedient to perform etching just in the pressure range between the minimum and the inflection point because under these conditions RF discharge occupies the total area of electrodes, polymer films do not form and to achieve the rate of etching Si in SF/sub 6/ /spl nu/=1/spl divide/2 microns/min it is sufficient to have 100 W of active power. We have obtained the approximate formula for the optimal pressure at which etching should be performed.