Method for uniformly polishing large scale plate
Disclosed is a substrate polishing method capable of minimizing a difference of polishing amounts between a center portion and a rim portion of a large scale plate during a plate polishing process.
1. A method for polishing a substrate by moving an upper plate having a polishing pad installed thereto,
wherein the upper plate performs a polishing process on an upper portion of the substrate with respect to a surface portion of the substrate along a quadrangular path,
wherein a travel range (S 1 ) by which the upper plate moves in the longitudinal direction of the substrate and a travel range (S 2 ) by which the upper plate moves in the transverse direction of the substrate are respectively 90% to 100% of a diameter (D) of the polishing pad installed to the upper plate; and
wherein S 1 and S 2 have a smallest value among values calculated by Formulas 1 and 2 below:
D
-
d
[
Formula
1
]
D
′
+
D
-
D
′
2
-
(
P
end
P
eff
)
[
Formula
2
]
where
d: double a radial length of a rim portion of the polishing pad, which does not contact the substrate;
D′: diameter of a portion of the polishing pad where the pressure applied to the substrate by the polishing pad is equal to or greater than an effective pressure (P eff ) which is capable of wearing the surface portion of the substrate;
P end : pressure applied to the substrate by the polishing pad at each outermost point in all portions of the polishing pad other than worn portions which do not contact the substrate; and
P eff : pressure applied to the substrate by the polishing pad, which is capable of wearing the surface portion of the substrate.
2. The method for polishing a substrate according to claim 1 , wherein the path forms a rectangle.
3. The method for polishing a substrate according to claim 1 , wherein the path forms a square.