Patent ID: 7927973

Claim:
A method for dividing a semiconductor wafer, the method comprising: placing a mask on a mask placement-side surface of the semiconductor wafer which has a plurality of semiconductor devices formed in unit-device-formation-regions, respectively, with the unit-device-formation-regions being regions in rectangular form partitioned by imaginary-dividing-lines and being some of a plurality of imaginary-divided-regions which are partitioned by the imaginary-dividing-lines that are respectively arranged in a grid-like arrangement on the semiconductor wafer and a circumferential line that is an outer periphery outline of the semiconductor wafer, wherein the mask is placed so as to define dividing lines for dividing the semiconductor wafer into individual pieces of the semiconductor devices by arranging the dividing lines on the wafer while aligning with the imaginary-dividing-lines, and so as to cover an entirety of surfaces of the wafer corresponding to respective remaining-regions, with the remaining-regions being regions in approximately quadrangular form and/or pentagonal form partitioned by the circumferential line of the wafer and the imaginary-dividing-lines and being regions which are not included in the unit-device-formation-regions, and so as to expose an entirety of surfaces of the wafer corresponding to respective removal-regions, with the removal-regions being regions in approximately triangular form partitioned by the circumferential line of the wafer and the imaginary-dividing-lines and being some of the imaginary-divided-regions; and performing plasma etching on the mask placement-side surface of the wafer on which the mask is placed, by which the semiconductor wafer is divided into the individual semiconductor devices along the defined dividing lines while portions corresponding only to dividing lines and the removal-regions of the wafer are removed, and while portions corresponding to the remaining-regions of the wafer remain such that only the dividing lines and the triangular regions are removed.