Methods for reducing warpage of bowed semiconductor substrates, particularly saddle-shaped bowed semiconductor substrates, are provided herein. Methods involve depositing a bow compensation layer by plasma enhanced chemical vapor deposition on the backside of the bowed semiconductor substrate by region, such as by quadrants, to form a compressive film on a tensile substrate and a tensile film on a compressive substrate. Methods involve flowing different gases from different nozzles on a surface of a showerhead to deliver various gases by region in a one-step operation or flowing gases in a multi-step process by shielding regions of the showerhead during delivery of gases to deliver specific gases from non-shielded regions onto regions of the bowed semiconductor substrate by alternating between rotating the semiconductor substrate and flowing gases to the backside of the bowed semiconductor substrate.