Patent ID: 7304721

Claim:
A method for dynamically monitoring a reticle, which is used for the photolithographic structuring of a semiconductor wafer in a projection apparatus, comprising: providing a reticle, the reticle having a pellicle, a reticle substrate, and an absorber layer, the absorber layer including absorbent elements designed in accordance with a circuit pattern; photolithographic structuring of layers of semiconductor wafers in a projection apparatus with the reticle using electromagnetic radiation at a predetermined wavelength; determining a number of reticle movements within and outside the projection apparatus; determining a time duration of reticle use; calculating a monitoring value from the number of reticle movements and from the time duration of reticle use; determining a dose value of the electromagnetic radiation at a location of the layer for each exposure; recording characteristics of a projection lens of the projection apparatus for the predetermined wavelength for each exposure; determining a clear field ratio of the reticle; determining an illuminated area of the semiconductor wafer; determining a radiant transmittance of the pellicle for the predetermined wavelength; determining a radiant transmittance of the absorber layer for the predetermined wavelength; determining a radiant transmittance of the reticle substrate for the predetermined wavelength; calculating a maximum number of wafer exposures from the monitoring value, from the dose value, from the characteristics of the projection lens, from the clear field ratio, from the illuminated area, from the radiant transmittance of the pellicle, from the radiant transmittance of the absorber layer, and from the radiant transmittance of the reticle substrate; and dynamically monitoring the reticle used in the photolithographic structuring of layers of the semiconductor wafers in accordance with the calculated maximum number of wafer exposures.