公开(公告)号：US09666411B1

公开(公告)日：2017-05-30

申请号：US14929812

申请日：2015-11-02

Applicant: KLA-Tencor Corporation

Inventor： Mark A. McCord ,  Gabor D. Toth

IPC: G21K5/04 ,  H01J37/26 ,  H01J37/285 ,  H01J37/20

CPC classification number: H01J37/265 ,  H01J37/026 ,  H01J37/20 ,  H01J37/285 ,  H01J2237/0044 ,  H01J2237/28

Abstract: One embodiment relates to an apparatus for virtual grounding of a target substrate in a charged-particle beam apparatus. A primary gun generates charged particles for a process beam that is focused on a frontside surface of the target substrate, and the target substrate is held by a stage. An electrostatic voltmeter measures a voltage potential of the target substrate, and a charge-control gun impinges a beam of charged particles to the target substrate. A feedback control loop is used to control the flood gun depending on the voltage potential measured by the electrostatic voltmeter. Other embodiments, aspects and features are also disclosed.