Reduction of Titanium Silicide Degradation During Borophosphosilicate Glass Reflow

The application of a self-aligned silicide (``salicide´´) process with Ti requires reduction of following excessive heat-treatment [1]. E.g. a commonly used borophosphosilicate glass (BPSG) reflow process (900 °C, 40 min, N2 has been found to cause severe morphological degradation of the TiSi2 layer [2] resulting in higher sheet resistance (RS). On the other hand the use of BPSG is advantageous because of its planarization capabilities and its gettering function of mobile alkali ions [3]. In this contribution the degradation mechanism and the influence of process parameters are investigated. As a result a Ti salicide process was established which was able to withstand following isolation oxide processes with temperatures of 900° C.