Electrical endpoint detection of VLSI contact plasma etching

A precise, in situ monitor of plasma contact etching is described. This method of electrical endpoint detection provides a dc electrical current which is proportional to the total open contacts and gives more than an order of magnitude improvement in signal-to-noise ratio over optical techniques. Endpoint detection is clearly deserved for total contact areas of less than 0.3 percent of a 3-in wafer. Using this method, contact resistances and leakage currents for both p+-n and n+-p junctions, are compatible to that of wet-etched or dry-etched contacts.