Patent Number: 
Section: claims

1. A method of regulating a dose of energy produced during continuous burst mode of an EUV light source comprising:(a) beginning a burst having a predetermined energy dose target;(b) timing by the laser controller a trigger to pulse a laser beam to irradiate a droplet during the burst;(c) sensing EUV energy generated by the droplet;(d) calculating by the laser controller a current dose error for the droplet based on the sensed EUV energy and the energy dose target;(e) accumulating by the laser controller a burst error based on the current dose error and a running burst error calculated for one or more preceding droplet during the burst;(f) repeating steps (b)-(e) for a next droplet when the burst is not finished and the accumulated burst error does not meet or exceed a threshold burst error;(g) mistiming by the laser controller the trigger to pulse the laser beam to not irradiate the next droplet when the burst is not finished and the accumulated burst error meets or exceeds the threshold burst error; and(h) repeating steps (c)-(g) until the burst is finished. 2. The method of claim 1 wherein the current dose error equals the sensed EUV energy minus the energy dose target. 3. The method of claim 2 wherein the accumulated burst error equalsrunning burst error+(gain*dose error). 4. The method of claim 3 wherein the gain is 1. 5. The method of claim 1 wherein the current dose error equals the energy dose target minus the sensed EUV energy. 6. The method of claim 5 wherein the accumulated burst error equalsrunning burst error+(gain*dose error). 7. The method of claim 6 wherein the gain is −1. 8. A system for regulating a dose of energy produced during continuous burst firing of an EUV light source configured to generate an energy dose target comprising:a drive laser configured to pulse a laser beam when a trigger is received;a sensor configured to sense EUV energy generated by irradiation of a droplet; anda controller configured to:(a) time the trigger to pulse a laser beam to irradiate a droplet during the burst;(b) calculate a current dose error for the droplet based on the sensed EUV energy and the energy dose target;(c) accumulate a burst error based on the current dose error and a running burst error calculated for one or more preceding droplet during the burst;(d) repeat steps (a)-(c) for a next droplet when the burst is not finished and the accumulated burst error does not meet or exceed a threshold burst error;(e) mistime the trigger to pulse the laser beam to not irradiate the next droplet when the burst is not finished and the accumulated burst error meets or exceeds a threshold burst error; and(f) repeat steps (b)-(e) until the burst is finished. 9. The system of claim 8 wherein the current dose error equals the sensed EUV energy minus the energy dose target. 10. The system of claim 9 wherein the accumulated burst error equalsrunning burst error+(gain*dose error). 11. The system of claim 10 wherein the gain is equal to 1. 12. The system of claim 8 wherein the current dose error equals the energy dose target minus the sensed EUV energy. 13. The system of claim 12 wherein the accumulated burst error equalsrunning burst error+(gain*dose error). 14. The system of claim 13 wherein the gain is −1.