Patent ID: 6960767

Claim:
An apparatus for determining a dimension of a semiconductor device feature, comprising: first and second sources of electrons; a first lens positioned proximate to the first source of electrons to receive a first electron beam emitted therefrom; a second lens positioned proximate to the second source of electrons to receive a second electron beam emitted therefrom; a plate having a first port and a second port extending through a thickness thereof, the first port spaced apart from the first lens to receive the first electron beam passing through the first lens, the second port spaced apart from the first port and from the second lens to receive the second electron beam passing through the second lens; a third lens configured to focus the first electron beam on a first position surface and positioned to receive the first electron beam passing through the first port; a fourth lens configured to focus the second electron beam on a second position surface and positioned to receive the second electron beam passing through the second port; and a support configured to engage the semiconductor device and located to receive the first and the second electron beams, at least one of the support and the sources of electrons being movable relative to each other.