Finding coating damages by scanning coating surface with a reduced beam

摘要

In EUV lithography, EUV light (e.g., at or around 13.5nm wavelength) is generated by a laser-produced plasma (LPP) source. At its most basic, an LPP source functions by converting a droplet of a fuel (such as tin) into plasma by irradiating the droplet with a high-power laser beam of infrared (IR) light (at or around 10.6 μn wavelength) which is produced by a C0_2 drive laser. The plasma produces the EUV light. This EUV light is used to expose a pattern into photoresist on a wafer. LPP light source systems typically comprise three major subsystems: the C0_2 drive laser, a beam transport system (BTS) and a source vessel, wherein the laser beam converts the fuel droplet into plasma.