Methods of forming semiconductor switching devices having silicide

Abstract

Methods of forming semiconductor switching devices include the steps of separating refractory or group VIII metals to be used on electrodes and contact regions from each other, so that subsequent conversion of these metal layers to metal silicide layers will not result in the formation of silicide bridge defects ('shorts'). In particular, a method of forming a semiconductor switching device is provided that includes the steps of forming an electrode on a semiconductor substrate and then forming a first metal layer having a first thickness on the electrode. A contact region of first conductivity type is also formed in the semiconductor substrate and then a second metal layer having a second thickness, less than the first thickness, is formed on the contact region. The first and second metal layers are then simultaneously converted to first and second metal silicide layers using a thermal treatment step. Moreover, prior to performing the conversion step, the first and second metal layers are electrically insulated from each other to prevent the likelihood of formation of bridge defects which may result when residues of metal silicide are formed on the substrate. In addition, the thicknesses of each of the metal layers is preferably chosen so that careful control of the final thicknesses of the metal silicide layers can be obtained to optimize the electrical characteristics of the switching device.