Abstract: Disclosed is an apparatus and a method in which off-droplet measurements instead of on-droplet measurements of prepulse energy are used for pulse energy control. Prepulse energy is measured during an off-droplet nonexposure period and controlled to a prepulse energy setpoint. The prepulse energy can then be controlled open-loop to the prepulse energy setpoint during on-droplet periods. This effectively decouples the EUV dose control loop from the prepulse energy control loop and avoids negative side effects of coupling such loops, for example, loss of the part of the dose adjustment range available to the dose controller.

Abstract: An optical lithography system is monitored. Information is received from the optical lithography system; a rule is accessed, the rule being associated with one or more of an event in the optical lithography system and an amount of time; a module stored in a library of modules is identified based on the accessed rule; whether a particular condition exists in the optical lithography system is determined using the identified module and the information received from the optical lithography system; and if the particular condition exists, a command signal is generated based on one or more characteristics of the particular condition and provided to an optical source of the optical lithography system. The command signal is based on the determined particular condition, and the command signal is sufficient to change one or more operating parameters of the optical source.

Abstract: An optical lithography system is monitored. Information is received from the optical lithography system; a rule is accessed, the rule being associated with one or more of an event in the optical lithography system and an amount of time; a module stored in a library of modules is identified based on the accessed rule; whether a particular condition exists in the optical lithography system is determined using the identified module and the information received from the optical lithography system; and if the particular condition exists, a command signal is generated based on one or more characteristics of the particular condition and provided to an optical source of the optical lithography system. The command signal is based on the determined particular condition, and the command signal is sufficient to change one or more operating parameters of the optical source.