<title>Reactive Etching Of Semiconductor Surfaces By Laser-Generated Free Radicals</title>

Abstract

Reactive etching at silicon and silicon -oxide surfaces is customarily carried out in a fluorocarbon plasma. Under such conditions, a large variety of reactive species is generated, making it extremely difficult to elucidate details of the etching mechanism; in addition, the charged species present in the plasma frequently produce undesirable radiation damage in the finished devices. We have found that dissociation of the parent fluorocarbons by multiple-infrared -photon excitation produces reactive neutral fragments which are capable of etching these surfaces. Etch gases such as CF3Br, CPZHC1, CF300CP3, and SF may be used with poly -Si, Si02, Si3N4, and other substrates; SEM, ESCA, and Auger diagnostics are employed to characterie the reactions occurring at the surface. From these experiments we hope to develop a quantitative model for the reactive etching process.Possible commercial advantages of the laser -etching technique include reduction or elimination of radiation damage, increased etching rates, and improved Si02 /Si specificity.