Patent ID: 8419891

Claim:
A knife edge ring apparatus for manufacturing a semiconductor device comprising: a body positioned a predetermined distance from a bottom surface of a semiconductor wafer, said body defined by an inner side wall, an outer side wall, a top surface, and a bottom surface; a multi-stage inclined portion formed in the outer side wall and inclined from said top surface towards an outer edge of said bottom surface; and a plurality of discharge holes, each discharge hole in the plurality of discharge holes having an inlet facing the semiconductor wafer and positioned along said multi-stage inclined portion, and penetrating said body to terminate in an outlet, wherein an inside diameter of each discharge hole narrows towards the outlet, wherein the multi-stage inclined portion has a first inclined portion surrounding a central portion of the body and a second inclined portion connected to the first inclined portion, the inclination of the first inclined portion towards the second inclined portion being greater than the inclination of the second inclined portion towards the bottom surface, the plurality of discharge holes comprising: a first discharge hole disposed along the first inclined portion and having an inlet with an internal diameter corresponding to a width of a top surface of the first inclined portion, and a second discharge hole disposed along the second inclined portion and having an inlet formed by first and second inner side walls, wherein an inclination of the first inner side wall closer to the body is less than an inclination of the second inner side wall with respect to a central axis of the second discharge hole.