Azimuthal critical dimension non-uniformity for double patterning process

A method for adjusting a position of a showerhead in a processing chamber, the method comprising:

• arranging a substrate on a substrate support in the processing chamber, wherein a plurality of mandrels are formed on the substrate;
• adjusting a position of the showerhead relative to the substrate support, wherein adjusting the position of the showerhead includes adjusting the showerhead to a tilted position based on data indicating a correlation between the position of the showerhead and azimuthal etching non-uniformities associated with etching the substrate, wherein the data indicates sensitivities of the azimuthal etching non-uniformities to respective positions of a plurality of different tilted positions of the showerhead and includes respective standard deviations of etch amounts across a surface of the substrate for each of the plurality of different tilted positions;
• and
• with the showerhead in the tilted position as adjusted based on the data, performing a trim step to etch the plurality of mandrels,
• wherein adjusting the position of the showerhead includes adjusting the position of the showerhead to a tilted position having a smallest standard deviation from among the respective standard deviations of the etch amounts across the surface of the substrate for each of the plurality of different tilted positions as indicated by the data.