In-laid metallization patterns, e.g., of copper or copper alloy, are formed in the surface of a dielectric layer with significantly improved reliability by voidlessly filling recesses formed in the dielectric layer surface by electroplating. Embodiments include preventing "pinching-off" of the recess opening due overhanging nucleation/seed layer deposits at the corners of the opening as a result of localized increased rates of deposition. Embodiments also include providing a dual-layered dielectric layer comprising different dielectric materials and performing a first, isotropic etching process of the upper (sacrificial) lamina of the dielectric layer for selectively tapering the width of the recess mouth opening to provide a wider opening at the substrate surface, followed by a second, anisotropic etching process for extending the recess at a substantially constant width for a predetermined depth into the lower lamina of the dielectric layer. The tapered width profile of the recess effectively prevents formation of overhanging deposits thereat which can result in occlusion and void formation during electroplating for filling the recesses. After electroplating, the recess-filled, plated surface is subjected to planarization processing, as by CMP, wherein the entire thickness of the second, upper lamina of the dielectric layer is removed.

A method is disclosed for forming openings in polyimide layers and for thereby forming semiconductor devices. The method allows for the forming of openings having tapered side walls and precise dimensional control. First and second layers of polyimide are sequentially formed on a surface. The first layer, in contact with the surface, is fully cured while the second layer is only partially cured. Overlying the second layer is a masking layer which can alternatively be an inorganic material or a resist material. A pattern is formed in the masking layer to expose portions of the upper polyimide layer. The pattern includes openings of predetermined size having a precise critical dimension. Using the patterned masking layer as an etch mask the upper layer of polyimide is isotropically etched in an etchent which etches the partially cured polyimide but which does not etch the fully cured underlying polyimide. The underlying polyimide layer is then anisotropically etched using the patterned masking layer as an etch mask to form openings in the cured polyimide layer having the same critical dimensions as in the masking layer pattern. The masking layer is then removed and the second polyimide layer is fully cured.

A method is provided for forming contact vias in an integrated circuit. Initially, a first buffer layer is formed over an insulating layer in an integrated circuit. The first buffer layer has a different etch rate from the insulating layer. A second buffer layer is then formed over the first buffer layer, with the second buffer layer having an etch rate which is faster than the first buffer layer. An isotropic etch is performed to create an opening through the second buffer layer and a portion of the first buffer layer. Because the second buffer layer etches faster than the first buffer layer, the slant of the sideswalls of the opening can be controlled. An anisotropic etch is then performed to complete formation of the contact via.

A method for forming a semiconductor device having a via by using a composite dielectric layer is disclosed. The method includes forming a first dielectric layer over a first conductive layer disposed on a substrate, where the first dielectric layer has a first etch rate. A second dielectric layer is then formed on the first dielectric layer, where the second dielectric layer has a second etch rate higher than the first etch rate. The second dielectric layer is isotropically removed by masking and etching to form a rounded contoured recess in the second dielectric layer using the first dielectric layer as an etch stop layer. The first dielectric layer is anisotropically removed by masking and etching to form the via in the first dielectric layer, where the bottom of the rounded contoured recess is aligned to the via.

The disclosure relates to techniques for etching layered materials to produce features with beveled edges, for example, wells in silicon oxide layers employed in integrated circuit fabrication. An anisotropic etch may be employed to form wells with vertical walls in the silicon oxide layer, and an isotropic etch may be employed to bevel peripheral corners of the walls. In preferred embodiments, a double mask of a photoresist layer on an underlying thin film may be used to define the limits of the anisotropic and isotropic etches, respectively.