Thermal field emission for low voltage scanning electron microscopy

Abstract

SUMMARY Low voltage scanning electron microscopy is a technique of great importance to the semiconductor industry, where inspection and testing of non‐conductive devices must be done at ∼ 1 keV beam energy. In order to perform scanning electron microscopy for inspection at high speed, improved cathodes are required in order to achieve good resolution at low energy with high beam current, the chromatic spread in the electron beam is shown to be the limiting factor in the SEM and a comparison of thermionic, field emission and Schottky cathodes is made to determine which can provide the best performance. It is concluded that a thermal field emission or Schottky, cathode is superior to either conventional field emission or thermionic cathodes.

Critical issues in scanning electron microscope metrology

“…For many applications, such as analytical microscopy and microfabrication, the CFE was not capable of producing the high currents and large spot sizes needed [ 59 , 75 ]. Work to develop a high current thermally assisted field emission cathode with relaxed vacuum and environment requirements was then begun [ 127 , 128 , 133 , 147 ].…”

Effects of fast secondary electrons to low-voltage electron beam lithography

“…A closely related quantity is the generalized oscillator strength (GOS) , f Gos (q) , defined 88 as: (3,36) where R y is the Rydberg energy.…”

Energy distribution measurement of a gallium liquid metal ion source modulated at high frequency by a focused laser beam

“…Since a temperature increase leads to an increase of the width of the energy distribution,4--7 and since the chromatic aberration of a FIB column is proportional to the energy spread of the beam, 8 an energy spread measurement of the LMIS with and without laser modulation is not only necessary but essential. Since a temperature increase leads to an increase of the width of the energy distribution,4--7 and since the chromatic aberration of a FIB column is proportional to the energy spread of the beam, 8 an energy spread measurement of the LMIS with and without laser modulation is not only necessary but essential.…”