Tylan5 and tylan6 are gas-phase doping furnaces. The furnaces are configured similarly to the oxidation furnaces with the addition of temperature controlled bubblers filled with BBr3 (as a boron source) and PoCl3 (a phosphorous source). N2 is ‘bubbled’ through the liquid sources and introduced into the quartz tube. Generally, the concentration of the dopant is solid solubility at the surfaces of the wafers. The labmember chooses both temperature and time of the pre-dep to determine the depth of the doping layer. Often times a separate ‘drive-in’ step is needed to achieve the depth desired. Between the pre-dep and drive-in furnace operations the glass that is formed during pre-dep must be removed by HF wet etching.