Laser Induced Chemical Etching of Silicon with SF₆ Using a Copper Bromide Vapour Laser

Abstract

Over the last 15 years, a wide range of laser induced chemical etching systems have been investigated [1]. Typically these studies have been concerned with etching that is initiated with either a tightly focused, cw scanning laser beam, or with a large area pulsed laser beam. In general, laser induced gaseous etching may be either photolytic — the main mechanism is the photodissociation of precursor or adsorbed reactant molecules, or pyrolytic — the basic mechanism is thermal. We present here our initial results on direct write dry pyrolytic etching of silicon with SF₆ using Copper Bromide Vapour Laser (CBVL). To the best of our knowledge this the first results of dry etching of any materials using Copper Vapour Laser (CVL) or CBVL. The CVL and the CBVL have a group of characteristics — wavelength, repetition rate and pulsewith, which make it unique to application in laser induced surface chemical processes. Our previous experience in the field of Laser Chemical Vapour Deposition of Al and Si using CVL and CBVL shows quite different effects with comparison with cw Ar+ laser [2 – 10]. In the literature there is information only about etching of Si with SF₆ molecules vibrationaly excited by CO₂ laser via multiple photon absorbtion [11].