Time of flight electron detector

A method for determining the material composition of a semiconductor device at an area of interest comprising:

• locating the area of interest on the semiconductor device;
• emitting a charged particle beam towards the area of interest such that electrons are caused to emanate from the area of interest;
• directing the electrons that emanate from the area of interest away from the path of the charged particle beam such that the electrons are directed toward a drift tube;
• receiving the electrons through an aperture of the drift tube;
• detecting the electrons arriving at a detector disposed opposite the aperture of the drift tube during specified time intervals;
• calculating a time of flight for each of the electrons arriving at the detector;
• generating an electron emission spectrum for the electrons from the time of flight calculations;
• identifying peaks in the electron emission spectrum;
• and
• identifying the materials associated with the area of interest by comparing the energies corresponding to the peaks in the electron emission spectrum with standard tables for known materials.

An apparatus for determining the energy of electrons emitted from a semiconductor device at an area of interest comprising:

• a charged particle device configured to emit a charged particle beam towards the area of interest such that electrons are caused to emanate from the area of interest;
• a spectrometer that receives the electrons that emanate from the area of interest;
• at least one detector that detects the electrons received by the spectrometer;
• an objective lens positioned between the semiconductor device and the spectrometer, the objective lens configured to attract and collimate the electrons that emanate from the area of interest and wherein the objective lens is configured to attract and collimate substantially all of the electrons that emanate from the area of interest;
• and
• a computing module coupled to the detector, wherein the computing module is configured to determine the energy and intensity of the electrons received by the spectrometer.

An apparatus for determining the energy of electrons emitted from a semiconductor device at an area of interest comprising:

• a charged particle device configured to emit a charged particle beam towards the area of interest such that electrons are caused to emanate from the area of interest and such that the charged particle beam forms a path;
• an objective lens disposed in the path of the charged particle beam, wherein the objective lens is configured to allow the charged particle beam to travel towards the area of interest, and wherein the objective lens is further configured to enable electrons emanating from the area of interest to be directed away from the area of interest and toward a redirecting lens as an electron beam;
• a redirecting lens disposed in the path of the charged particle beam and in the path of the electron beam, the lens configured to redirect the electron beam toward a focusing lens;
• the focusing lens configured to focus the redirected electron beam on a detector system;
• the detector system including an electron time-of-flight spectrometer arranged to receive the focused electron beam from the focusing lens;
• and
• a computing module coupled to the electron time-of-flight spectrometer for counting and determining the time of flight for each of the electrons received by the electron time-of-flight spectrometer.