| 摘要 |
Disclosed are methods and apparatus for reflecting, towards a sensor, extreme ultra-violet (EUV) light that is reflected from a target substrate. The system includes a first mirror arranged to receive and reflect the EUV light that is reflected from the target substrate, a second mirror arranged to receive and reflect the EUV light that is reflected by the first mirror, a third mirror arranged to receive and reflect the EUV light that is reflected by the second mirror, and a fourth mirror arranged to receive and reflect the EUV light that is reflected by the third mirror. The first mirror has an aspherical surface. The second, third, and fourth mirrors each have a spherical surface. |
