PVD system and collimator

A physical vapor deposition (PVD) system, comprising:

• a pedestal configured to hold a semiconductor wafer;
• a cover plate configured to hold a target;
• and
• a collimator disposed between the pedestal and the cover plate, wherein:
• the collimator has an upper surface facing the cover plate and a lower surface facing the pedestal, wherein the lower surface is flat, and the upper surface is non-flat, and
• the collimator has a plurality of sidewall sheets defining a first plurality of passages in a peripheral portion of the collimator to each have a same width dimension between adjacent ones of the plurality of sidewall sheets and a same first vertical dimension, and defining a second plurality of passages in a central portion of the collimator to each have the same width dimension between adjacent ones of the plurality of sidewall sheets and a respective second vertical dimension, each respective second vertical dimension being smaller than the same first vertical dimension.

A method of using a physical vapor deposition (PVD) system, the method comprising:

• holding a semiconductor wafer with a pedestal;
• holding a target with a cover plate;
• with a first plurality of passages of a collimator, passing source material travelling from the target toward the pedestal at an angle less than a first threshold angle with respect to a line perpendicular to a surface of the pedestal facing the cover plate;
• with a second plurality of passages of the collimator, passing source material travelling from the target toward the pedestal at an angle less than a second threshold angle with respect to the line, wherein the first threshold angle is greater than the second threshold angle;
• with a first plurality of sidewall sheets of the collimator, blocking source material travelling from the target toward the pedestal at an angle greater than the first threshold angle with respect to the line;
• and
• with a second plurality of sidewall sheets of the collimator, blocking source material travelling from the target toward the pedestal at an angle greater than the second threshold angle with respect to the line;
• and
• wherein the collimator has an upper surface and a lower surface, the lower surface is flat, and the upper surface is non-flat, and
• wherein the collimator has a plurality of sidewall sheets defining a first plurality of passages in a peripheral portion of the collimator to each have a same width dimension between adjacent ones of the plurality of sidewall sheets and a same first vertical dimension, and defining a second plurality of passages in a central portion of the collimator to each have the same width dimension between adjacent ones of the plurality of sidewall sheets and a respective second vertical dimension, each respective second vertical dimension being smaller than the same first vertical dimension.