Patent ID: 8053036

Claim:
A method of designing and producing a shower plate for a plasma CVD apparatus wherein a wafer is placed on a susceptor, above which the shower plate is disposed substantially in parallel for discharging a gas therethrough and generating a plasma between the susceptor and the shower plate, comprising: (a) providing a shower plate having a convex surface configured by a convex equation L which is a function of a radius R; (b) obtaining uniformity data of thickness of a film formed on a wafer placed on the susceptor using the shower plate in the plasma CVD apparatus; (c) determining a distribution of thickness of the film formed on the wafer by dividing a diametrical cross section of the film into multiple regions including a concave region wherein the thickness of the film is smaller than an average thickness of the film, a convex region wherein the thickness of the film is greater than the average thickness of the film, and an even region wherein the thickness of the film is substantially even with the average thickness of the film, wherein boundaries between the multiple regions are disposed on a straight line representing the diametrical average thickness of the film as viewed on a graph on the diametrical cross section; (d) determining a secondary equation M 1 which has a highest vertex point aligned with a lowest point of the concave region as viewed on the graph in a direction perpendicular to the diametrical direction and which intercepts the straight line on the graph; (e) determining a secondary equation M 2 which has a lowest vertex point aligned with a highest point of the convex region as viewed on the graph in a direction perpendicular to the diametrical direction and which intercepts the straight line on the graph; (f) designing a surface configuration of the shower plate by (I) overlaying the secondary equation M 1 on the equation L in a region corresponding to the concave region as viewed on the graph on the diametrical cross section by moving the secondary equation M 1 in a direction perpendicular to the diametrical direction so that a point where the secondary equation M 1 intercepts the straight line is on the equation L on the graph; and (II) overlaying the secondary equation M 2 on the equation L in a region corresponding to the convex region as viewed on the graph on the diametrical cross section by moving the secondary equation M 2 in a direction perpendicular to the diametrical direction so that a point where the secondary equation M 2 intercepts the straight line is on the equation L on the graph; and (j) producing a shower plate having the surface configuration designed in step (f).