Abstract: Two methods for wet etch removing an etch stop layer without leaving an undesired undercut are disclosed. In the first method, a reactive ion etch is stopped on an etch stop layer. The exposed etch stop is wet etch removed, leaving an undesirable undercut. The undercut is filled by chemical vapor deposition of a fill material. The filler is then etched to leave a smooth aperture without undercuts. This last etch may be a sputter etch followed by a plasma etch. In the second method, a reactive ion etch is stopped on an etch stop layer as in the first method. Sacrificial sidewalls are then formed within the aperture. The exposed etch stop layer is then removed by wet etching, the positioning of the sidewalls serving to prevent undercutting of the etch stop layer. Finally, the sacrificial sidewalls are etched.

Abstract: A process for forming elongated solder terminals to connect a plurality of pads on a semiconductor device to a corresponding plurality of pads on a supporting substrate by,forming a means to maintain a predetermined vertical spacing between the semiconductor and the supporting substrate outside the area of the pads,forming and fixing solder extenders to each of the solder wettable pads on the substrate or the device to be joined,positioning the semiconductor device provided with solder mounds on the solder mountable pads over the supporting substrate with the solder mound in registry and with the pads on the substrate with the solder extenders positioned therebetween, the means to maintain vertical spacing located between and in abutting relation to the device and substrate, andheating the resulting assembly to reflow the solder mounds and the solder extenders while maintaining a predetermined spacing thus forming a plurality of hour-glass shaped elongated connections.