Abstract: A silicon wafer grinding apparatus, a retaining assembly used for the same, and a silicon wafer flatness correcting method are provided More particularly, a silicon wafer grinding apparatus, a retaining assembly used for the same, and a silicon wafer flatness correcting method for correcting a wafer flatness in a final grinding process are provided The silicon wafer grinding apparatus includes a grinding surface plate having a grinding pad attached thereon; a grinding head arranged opposite to the grinding surface plate and rotated in the same direction as that of the grinding surface plate; a backing film attached at a lower portion of the grinding head for supporting a wafer; and a retainer ring having an inner diameter (a wafer diameter +?) greater than a diameter of the wafer by as much as a and disposed on the backing film. By forming a diameter or physical properties of a part of the backing film of the wafer retaining assembly, the wafer flatness of the final grinding may be corrected.