Method of electrochemically fabricating multilayer structures having improved interlayer adhesion

摘要

Multi-layer microscale or mesoscale structures are fabricated with adhered layers (e.g. layers that are bonded together upon deposition of successive layers to previous layers) and are then subjected to a heat treatment operation that enhances the interlayer adhesion significantly. The heat treatment operation is believed to result in diffusion of material across the layer boundaries and associated enhancement in adhesion (i.e. diffusion bonding). Interlayer adhesion and maybe intra-layer cohesion may be enhanced by heat treating in the presence of a reducing atmosphere that may help remove weaker oxides from surfaces or even from internal portions of layers.

主权项

1. A fabrication process for forming a plurality of multi-layer three-dimensional structures, comprising:
(a) providing a substrate; (b) forming and adhering a first multi-material layer to a substrate, wherein the first multi-material layer comprises a desired pattern of at least one structural metal and at least one sacrificial metal; (c) forming and adhering a subsequent multi-material layer to a previously formed layer, wherein the forming and adhering of the subsequent multi-material layer comprises:
a. selectively depositing at least one first metal using an adhered photoresist mask and thereafter removing the mask;b. depositing at least one second metal after removal of the mask; andc. planarizing the at least one first metal and the at least one second metal of the subsequent multi-material layer to set a boundary level for the subsequent multi-material layer, wherein the at least one first metal and the at least one second metal comprise at least one structural material and at least one sacrificial material; (d) repeating the forming and adhering operations of (b) and (c) at least once to build up a plurality of three-dimensional structures from a plurality of adhered multi-material layers; (e) after the forming of the plurality of adhered layers, releasing the plurality of three-dimensional structures from the at least one sacrificial material; (f) after formation of the plurality of adhered layers, subjecting the multi-layer structure to a heat treatment, wherein a maximum effective temperature during heat treatment is less than a recrystallization temperature of a selected one of the at least one structural material and is in a range of 150° C.-350° C., and wherein the heat treatment is applied for a sufficient time, at a sufficient temperature, and in an environment that results in average interlayer adhesion strength of the selected one of the at least one structural material exceeding one half of the average intra-layer yield strength of the selected one structural material after heat treatment.