Processes for fabricating low-force wafer test probes and their structures

Abstract

Embodiments herein describe structures of low-force wafer test probes and formation thereof. Structures of low-force wafer test probes and their formation via gray scale etch or electroplating is described. Structures are described that include a lower base structure on top of a substrate and an upper blade structure on top of the lower base structure. In various embodiments, a crown of a C4 bump is accommodated by one or both of: i) a cavity present in the lower base structure; and ii) a height of the upper blade structure. Processes for fabricating probe structures are described that include forming lower base structures upon a substrate and forming upper blade structures on top of the lower base structures. The upper blade structures include at least one blade. Each of the blade(s) include a cutting edge that points toward a center point within the probe structure.

What is claimed is: 
     
         1 . A probe structure for cutting into an oxide layer of C4 bump comprising:
 a lower base structure on top of a substrate, wherein the lower base structure includes a toroid layer of conductive material that rests on top of a circular pad of conductive material; and   an upper blade structure on top of the lower base structure, wherein:
 (a) a crown of a C4 bump is accommodated by both of the following: (i) a cavity present in the lower base structure, wherein the cavity present in the lower base structure is bowl-shaped; and (ii) a height of the upper blade structure; 
 (b) the upper blade structure includes one or more blades, wherein (i) one or more cutting edges of the one or more blades point towards a center position of the probe structure and (ii) the one or more cutting edges of the one or more blades are between 0 μm and approximately 10 μm from an edge of the cavity present in the lower base structure; 
 (c) the upper blade structure includes a blade supporting wall; and 
 (d) the upper blade structure has a height of at least 35 μm.