Patent ID: 8305557

Claim:
A method for calculating a transmission utility factor value of photo energy of an exposure device, the method comprising the steps of: dividing a wafer into a plurality of cells; calculating an area of one of the cells by multiplying horizontal and vertical values of the cell; exposing the cell with a laser; calculating an energy value used to expose the cell by multiplying the area of the cell by an energy value to expose a unit exposure area; calculating a total number of laser pulses generated from a laser generator in order to expose the cell; calculating an energy value of each pulse; multiplying the total number of laser pulses by the energy value of each pulse to determine an energy value generated by the laser to expose the cell; calculating a photo energy transmission utility factor value by comparing the energy value used to expose the cell with the energy value generated by the laser to expose the cell; comparing the photo energy transmission utility factor value with a preset value; and determining that the optical system is contaminated when the photo energy transmission utility factor value decreases from the preset value by more than a preset amount.