Validity and Application of the TCR Method to MOL contactS
As structure size decreases, electron scattering and liner conduction effects may lead to inaccuracy in the TCR method. To investigate these potential issues for tungsten systems, resistivity, grain size, and temperature derivatives of sheet resistance are measured as a function of thickness for CVD deposited films. Liner conduction was found to impact the apparent temperature dependence of sheet resistance for thin W films. W films exhibit a dp/dT value 39% higher than reported in literature for bulk. The effect of electron scattering at surfaces and grain boundaries on the temperature derivative of sheet resistance is predicted from common classical scattering models and it is concluded that these mechanisms do not play a significant role. It was also found that TCR accuracy is improved in W contact structures by using the derivative of resistivity determined from the W blanket film analysis. In addition, we also calculated TCR values from first principles which are in good agreement to our experimental results.