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.