公开(公告)号：US09755396B1

公开(公告)日：2017-09-05

申请号：US15363570

申请日：2016-11-29

Applicant: ASML Netherlands B.V.

Inventor： Paul Frihauf ,  Andrew Liu ,  Spencer Rich ,  Matthew R. Graham ,  Steven Chang ,  Wayne J. Dunstan ,  Daniel Jason Riggs

IPC: H01S3/10 ,  H05G2/00 ,  H01S3/102 ,  H01S3/106 ,  H01S3/107

CPC classification number: H01S3/102 ,  H01S3/005 ,  H01S3/10038 ,  H01S3/1068 ,  H01S3/107 ,  H01S3/2232 ,  H05G2/003 ,  H05G2/008

Abstract: A method and apparatus for control of a dose of extreme ultraviolet (EUV) radiation generated by a laser produced plasma (LPP) EUV light source that combines pulse control mode and pulse modulation. The EUV energy created by each pulse is measured and total EUV energy created by the fired pulses determined, a desired energy for the next pulse is determined based upon whether the total EUV energy is greater or less than a desired average EUV energy times the number of pulses. If the desired pulse energy for the next droplet is within the range of one or more pulse modulation actuators, the pulse is modulated; otherwise, the pulse is fired to miss the droplet. This provides greater control of the accumulated dose as well as uniformity of the EUV energy over time, greater ability to compensate for pulses that generate EUV energy that is higher or lower than nominal expected values, and ability to provide an average EUV energy per pulse that is less than the nominal minimum EUV energy per pulse of the system.