Abstract: Contact holes through a dielectric are formed by forming a layer of polysilicon having a thickness between 0.02 um and 0.15 um inclusive on the dielectric, forming a layer of resist having a thickness between 0.4 um and 0.6 um inclusive on the layer of polysilicon, making a mask of the layer of resist, using it to form a mask in the layer of polysilicon and etching contact holes in the dielectric by exposing it to etching gasses through the apertures in the polysilicon mask. When the dielectric includes a layer of oxide adjacent the polysilicon mask and a layer of nitride between it and elements of the device, the resist mask is removed prior to etching the contact hole and a gas mixture of: C.sub.4 F.sub.8 ; one of Ar, H, F; CO; CF.sub.4 or C.sub.2 F.sub.6 is used.

Abstract: An etch chamber for anisotropic and selective etching of a semiconductor wafer contains a dielectric window and an externally located first electrode member adjacent to the dielectric window for generating a plasma within the chamber. A second electrode member is located within the chamber for exciting the plasma generated by the first electrode member. A third electrode is located between the first electrode member and the dielectric window for sputtering the dielectric window to provide sidewall passivation for anisotropic and selective etching of a semiconductor wafer located within said chamber. Each electrode member is powered by its own separate RF generator. This arrangement enables the independent control of each of the three electrode members to optimize the etching of the semiconductor wafer located within the chamber.