Patent ID: 11996258

Abstract:
A planar filament 11f can include multiple materials to increase electron emission in desired directions and to suppress electron emission in undesired directions. The filament 11f can include a core-material CM between a top-material TM and a bottom-material BM. The top-material TM can have a lowest work function WFt; the bottom-material BM can have a highest work function WFb; and the core-material CM can have an intermediate work function WFc (WFt<WFc<WFb). A width Wt of the filament 11f at a top-side 31t can be greater than its width Wb at a bottom-side 31b (Wt>Wb). This shape makes it easier to coat the edges 31e with the bottom-material BM, because the edges 31e tilt toward and partially face the sputter target. This shape also helps direct more electrons to a center of the target 14, and reduce electron emission in undesired directions.