PVD system and collimator

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;
• 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,
• wherein the first threshold angle is greater than the second threshold angle;
• a central portion of the collimator has a cross sectional shape defined by a rectangle from which a trapezoid has been subtracted to form a cutout, wherein the first plurality of passages are in the central portion and the second plurality of the passages are outside the central portion.

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 between the pedestal and the cover plate, wherein the collimator is configured to pass source material travelling from the cover plate toward the pedestal at an angle less than a threshold angle with respect to a line perpendicular to a surface of the pedestal facing the cover plate, wherein the collimator is configured to block source material travelling from the cover plate toward the pedestal at an angle greater than the threshold angle, wherein at least a portion of the collimator has a cross sectional shape defined by a first rectangle from which a central trapezoid portion of the first rectangle has been subtracted to form a cutout.