Embodiments herein present a method for a feed forward silicide control scheme based on spacer height controlling pre-clean time. The method forms field effect transistor gates over a substrate and then forms spacers on the gates. Next, the method measures the spacers using an atomic force microscope to determine a measured spacer height. The method then conducts a pre-cleaning etch, wherein a duration of the pre-cleaning is adjusted according to the measured spacer height. If the measured spacer height is below a predetermined amount, the duration of the pre-cleaning is reduced; and, if the measured spacer height is above a predetermined amount, the duration of the pre-cleaning is increased.