Beam-Lead Technology

This paper describes a process developed to batch-fabricate semiconductor devices and integrated circuits with electroformed electrodes cantilevered beyond the edges of the wafer -- hence, the name beam leads. 1 This type of structure simplifies the assembly and interconnection of individual units and integrated circuits, provides its own protective seal, and leads to a new class of integrated circuits 2 where the isolation is accomplished by etched trenches under the metal bridging connections. Fig. 1 is a drawing of a silicon high-frequency beam-lead transistor. The 0.5-mil thick leads are cantilevered beyond the edge of the silicon chip, and are used for structural support of the chip as well as electrical contact. The beam leads may be bonded to a metal-filmed substrate with a matching pattern, obviating the need for eutectic brazing to the substrate. This structure imposes no electrical penalty on the 233 234 T H E BELL SYSTEM TECHNICAL J O U R N A L , F E B R U A R Y 1966 COLLECTOR