Method to prevent oxide peeling induced by sog etchback on the wafer edge

Abstract

A method for avoiding oxide peeling by removing polymer contaminants from the edge of a wafer is described. An interlevel dielectric sandwich layer is formed by depositing a first oxide layer overlying semiconductor device structures in and on a semiconductor substrate, coating a spin-on-glass layer overlying the first oxide layer and rinsing the spin-on-glass layer whereby an edge bead rinse hump is formed a first distance from the edge of the wafer, etching back the spin-on-glass layer wherein the wafer is held by a clamp a second distance from the edge of the wafer wherein the second distance is smaller than the first distance and wherein the etching back of the spin-on-glass layer forms the polymer on the surface of the first oxide layer under the clamp at a third distance between the first and second distances, and depositing a second oxide layer overlying the etched back spin-on-glass layer and the polymer at the edge of the wafer to complete the interlevel dielectric sandwich layer. A layer of photoresist is coated overlying the sandwich layer wherein the photoresist layer does not extend closer to the edge of the wafer than the third distance and patterned to form a photoresist mask. The interlevel dielectric sandwich layer is etched away where it is not covered by the mask to form via openings wherein the second oxide layer overlying the polymer is etched away. The photoresist mask is stripped whereby the polymer is also removed thereby avoiding oxide peeling at the edge of the wafer.