Apparatus of Plural Charged Particle Beams with Multi-axis Magnetic Lenses

摘要

A new apparatus of plural charged particle beams with multi-axis magnetic lenses is provided, which comprises a plurality of sub-columns The apparatus employs two modified multi-axis magnetic lenses, and magnetic sub-lenses thereof therefore function as the objective lenses and the condenser lenses of all the sub-columns respectively. The plurality of sub-columns can perform the same function or different functions required for observing a surface of a specimen, such as high-throughput inspection and high-resolution review of interested features thereon. Accordingly, the apparatus can be used as a yield management tool in semiconductor manufacturing industry.

主权项

1. An apparatus of plural charged particle beams, comprising:
a specimen stage for sustaining a specimen thereon; and multiple sub-columns above said specimen stage, wherein each of said multiple sub-columns performs a function for observing an observed surface of said specimen and comprises:
a charged particle source unit for providing a primary charged particle beam propagating along an optical axis of said each sub-column;a magnetic condenser lens under said charged particle source unit and aligned with said optical axis;a beam-limit aperture plate having at least one first opening and under said magnetic condenser lens, wherein one of said at least one first opening is aligned with said optical axis and therefore functions as a beam-limit aperture;a signal-charged-particle detector under said beam-limit aperture plate; anda deflection scanning unit and a magnetic objective lens both under said signal-charged-particle detector and aligned with said optical axis,wherein said magnetic condenser lens focuses said primary charged particle beam to get a desired current thereof after passing through said beam-limit aperture, said magnetic objective lens focuses said primary charged particle beam onto said observed surface, said signal-charged-particle detector detects secondary charged particle beam emanated from said observed surface where said primary charged particle beam impinges, and said deflection scanning unit deflects said primary charged particle beam to scan said observed surface so that an image thereof can be obtained, wherein each of said magnetic objective lenses of said multiple sub-columns is one magnetic objective sub-lens of a multi-axis magnetic objective lens, wherein said multi-axis magnetic objective lens comprises:
a pair of parallel first magnetic conductor plates with a plurality of first through holes in pairs therein, wherein each pair of said first through holes comprises a first upper hole and a first lower hole which are respectively inside a first upper plate and a first lower plate of said pair of parallel first magnetic conductor plates and aligned with said optical axis of said each sub-column;a plurality of first magnetic round rings in pairs, wherein each pair of said first magnetic round rings comprises a first upper ring and a first lower ring which are inside, aligned and form a first upper radial gap and a first lower radial gap with said first upper and lower holes of one pair of said first through holes respectively, and said first upper and lower radial gaps are vacuum or filled of non-magnetic or weakly-magnetic material; anda first annular magnetic-flux excitation unit which is between said first upper and lower plates and has an inner outline which encloses said plurality of first through holes in pairs in radial dimensions,wherein one pair of said first through holes, one pair of said first magnetic round rings therein and a first magnetic-circuit gap between said first upper and lower rings thereof therefore forms one magnetic objective sub-lens module, and said first annular magnetic-flux excitation unit provides a first magnetic flux to each magnetic objective sub-lens module which therefore becomes said one magnetic objective sub-lens, wherein each of said magnetic condenser lenses of said multiple sub-columns is one magnetic condenser sub-lens of a multi-axis magnetic condenser lens, wherein said multi-axis magnetic condenser lens comprises:
a pair of parallel second magnetic conductor plates with a plurality of second through holes in pairs therein, wherein each pair of said second through holes comprises a second upper hole and a second lower hole which are respectively inside a second upper plate and a second lower plate of said pair of parallel second magnetic conductor plates and aligned with said optical axis of said each sub-column;a plurality of second magnetic round rings in pairs, wherein each pair of said second magnetic round rings comprises a second upper ring and a second lower ring which are inside, aligned and form a second upper radial gap and a second lower radial gap with said second upper and lower holes of one pair of said second through holes respectively, and said second upper and lower radial gaps are vacuum or filled of non-magnetic or weakly-magnetic material; anda second annular magnetic-flux excitation unit which is between said second upper and lower plates and has an inner outline which encloses said plurality of second through holes in pairs in radial dimensions,wherein one pair of said second through holes, one pair of said second magnetic round rings therein and a second magnetic-circuit gap between said second upper and lower rings thereof therefore forms one magnetic condenser sub-lens module, and said second annular magnetic-flux excitation unit provides a second magnetic flux to each magnetic condenser sub-lens module which therefore becomes said one magnetic condenser sub-lens.