Laser interference fringe control for higher euv light source and euv throughput

A method for generating extreme ultraviolet (EUV) radiation, comprising:

• generating two or more fringes by a first laser beam passing through a first pair of slits;
• irradiating two or more target droplets by the two or more fringes to produce EUV radiation, wherein each one of the two or more target droplets simultaneously pass one of the two or more fringes;
• and
• collecting and directing the EUV radiation produced from the two or more target droplets by an imaging mirror.

An extreme ultraviolet (EUV) radiation source, comprising:

• a first laser source configured to generate a first laser beam;
• a collector mirror comprising two or more slits;
• a droplet generator configured to simultaneously release two or more target droplets in first parallel lines in a first plane;
• an optical system configured to divide the first laser beam into two or more portions and to pass the two or more portions of the first laser beam through the two or more slits to generate two or more first fringes in parallel with a path of the two or more target droplets;
• and
• a controller coupled to and controlling the first laser source and the droplet generator, wherein the controller is configured to fire a laser pulse of the first laser source to irradiate the simultaneously released two or more target droplets by the two or more first fringes, wherein each first fringe irradiates one droplet.