Patent ID: 8641913

Claim:
A method of forming an element having microcontacts, comprising: (a) providing a first etch-resistant material at selected locations on a top surface of a substrate, a first metal being exposed at the top surface, wherein the substrate includes a first metal layer including the first metal, a second metal layer exposed at a bottom surface of the substrate, and a third metal layer between the first and second metal layers, the third metal layer including a metal different from a metal of the first and second metal layers; (b) etching the first metal at the top surface of the substrate by applying processing to the substrate from a location above the top surface at locations not covered by the first etch-resistant material and thereby forming first microcontact portions projecting upwardly at the selected locations; (c) providing a second etch-resistant material on the first microcontact portions; (d) further etching the first metal of the substrate to form second microcontact portions below the first microcontact portions, the second etch-resistant material at least partially protecting the first microcontact portions from etching during the further etching step, thereby patterning the first metal layer selectively with respect to the third metal layer; (e) patterning the second metal layer by applying processing to the substrate from a location below the bottom surface of the substrate to form the second metal layer into electrically conductive traces extending in lateral directions defining a plane; and (f) removing portions of the third metal layer to leave the microcontacts and the traces, such that the second microcontact portions extend away from the traces in a vertical direction transverse to the plane, wherein the microcontacts are configured to be bonded by at least one of solder, eutectic, or diffusion bonding to corresponding contacts on a face of a microelectronic element, the microcontacts are arranged in an array having a plurality of rows of microcontacts and a plurality of columns of microcontacts, and each microcontact is generally in the form of a body of revolution about a central axis.