Patent ID: 8023102

Claim:
A method of monitoring the state of a reticle comprising: providing a first reticle having a first device exposure region with opaque regions and transparent regions; providing said first reticle in a first imaging tool; defining one or more image fields across said first device exposure region; providing a second reticle having a second device exposure region, said first and second reticles being identical reticles; defining an allowable transmission variance threshold for said first and second reticles, said allowable transmission variance threshold identifying whether said first and second reticles will transfer substantially equivalent images; providing said second reticle in a second imaging tool; defining said one or more image fields across said second device exposure region of said second reticle; transmitting a first energy from a first energy source through said first device exposure region of said first reticle; transmitting a second energy from a second energy source through said second device exposure region of said second reticle; detecting in each of said first and second imaging tools said first and second transmitted energies within said one or more image fields across said first and second reticles at a testing interval; generating transmission profiles of each of said first and second detected energies for said one or more image fields across said first and second reticles; determining a state of each said first and second reticle based on said first and second transmission profiles; monitoring equivalence of said identical first and second reticles by comparing each of said first transmission profile of said first reticle and said second transmission profile of said second reticle with said allowable transmission variance threshold to determine whether said first and second reticles will transfer substantially equivalent images; and performing an action based on said state of each said reticle.