Patent ID: 9000403
Filing Date: 2015-04-07
Classification: G03F,H05G

Abstract:
1. A method of controlling the output of an EUV LLP system having seed lasers which produce pre-pulses and main pulses, comprising: operating the seed lasers to generate a pre-pulse and a main pulse, each of the pre-pulse and the main pulse having a respective pulse width; amplifying the main pulse with an amplifier having a duty cycle controlled RE pump rate and irradiating a target material with the amplified pukes to generate an EUV output having energy; adjusting the pulse width of the main pulse by shortening the pulse width of the main pulse if the generated EUV output energy is above a desired EUV output energy and lengthening the pulse width of the main pulse if the EUV energy is below the desired EUV output energy; adjusting the duty cycle by increasing the duty cycle if the pulse width of the main pulse is longer than a desired range and decreasing the duty cycle if the pulse width of the main pulse is shorter than the desired range.