Grid assembly for ion beam sources and method therefor

Abstract

A grid assembly for ion beam sources includes grid structures that are etched from a semiconductor wafer using microelectronic fabrication techniques with the grid structures constrained in an aligned manner by a ceramic carrier having embedded electrically conductive pads for effecting electrical contact with the grid structures. The grid structures are fabricated by creating oxide and photoresist layers on a starting silicon wafer and exposing the photoresist through a mask carrying the aperture pattern. After the photoresist is developed, the oxide layer is etched to form openings therethrough and the silicon wafer is anisotropically etched from both sides with the etching proceeding anisotropically so that the {111} planes are etched to form the apertures in which the {111} planes face each other across the aperture with opposite {111} planes at a 90.degree. angle relative to one another to provide a plurality of apertures each defining a volume in the form of an inverted truncated 4-sided pyramid. The ceramic carrier is assembled as a preform from a flexible Al.sub.2 O.sub.3 /polymer dielectric tape and is initially fabricated by cutting the various laminae L.sub.1, L.sub.2, L.sub.n-1, . . . L.sub.n into the desired configuration and assembling the laminae in a stacked configuration for burnout and firing to form a unitary ceramic carrier. The etchant formed grids are cemented into place in the carrier with an electrically conductive high-temperature cement.