Short wavelength metrology imaging system
US7268945B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 10, 2003 |
| Grant date | Sep 11, 2007 |
| Priority date | — |
| Expiry date | Jun 29, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG21K2207/005
- WIPO fieldMicro-structural and nano-technology
- WIPO sectorChemistry
Abstract
An extreme ultraviolet (EUV) AIM tool for both the EUV actinic lithography and high-resolution imaging or inspection is described. This tool can be extended to lithography nodes beyond the 32 nanometer (nm) node covering other short wavelength radiation such as soft X-rays. The metrology tool is preferably based on an imaging optic referred to as an Achromatic Fresnel Optic (AFO). The AFO is a transmissive optic that includes a diffractive Fresnel zone plate lens component and a dispersion-correcting refractive lens component. It retains all of the imaging properties of a Fresnel zone plate lens, including a demonstrated resolution capability of better than 25 nanometers and freedom from image distortion. It overcomes the chromatic aberration of the Fresnel zone plate lens and has a larger usable spectral bandwidth. These optical properties and optical system designs enable the development of the AFO-based AIM tool with improved performance that has advantages compared with an AIM tool based on multilayer reflective mirror optics in both performance and cost.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.