A Comparative Study between Total Thickness Variance and Site Flatness of Polished Silicon Wafer

Monocrytalline silicon wafers of wide range of total thickness variance (TTV) were produced and evaluated. Site total indicator readings (STIR) with different reference plane-site front least square focal plane range (SFQR) and site back ideal focal plane range (SBIR) were compared with TTV. SBIR was found to be correlated with TTV but not correlated with SFQR. This result indicates that process development procedure should be separately considered for SBIR and SFQR, respectively.