| 主权项 |
1. A shower plate adapted to be installed in a plasma deposition apparatus comprising a reaction chamber with a gate valve, a showerhead, and a susceptor, said shower plate being adapted to be attached to the showerhead and said shower plate comprising:
a front surface adapted to face the susceptor; and a rear surface opposite to the front surface, wherein the shower plate has multiple apertures each extending from the rear surface to the front surface for passing gas therethrough in this direction, and the shower plate has at least one quadrant section defined by radii, wherein the one quadrant section has an opening ratio of a total volume of openings of all the apertures distributed in the one quadrant section to a total volume of the one quadrant section, said opening ratio being substantially smaller than an opening ratio of any other quadrant section of the shower plate, wherein the at least one quadrant section includes a first, second and third regions, as viewed from the front, defined by lines each extending from the center of the shower plate to an outer periphery of the shower plate, the first region being disposed rotationally asymmetrically, the second and third regions being smaller than and disposed next to the first region, respectively, and the first, second, and third regions have a first, second, and third opening ratios of a total volume of openings of all the apertures distributed in the respective regions to a total volume of the respective regions, wherein the second and third opening ratios are each smaller than the opening ratio of the any other quadrant section but are each greater than the first opening ratio. |
