Focused ion beam induced optical emission spectroscopy

Abstract

We describe a focused ion beam system and a spectroscopic technique that utilize photons emitted from electronically excited sputtered neutrals for surface element identification and end-point detection. When a target is bombarded by a focused ion beam, some of the sputtered atoms (as much as 0.2%) leave the surface in electronically excited states and then quickly decay (10−6–10−8 s) by emitting photons of characteristic energies. A sputter-induced optical emission spectrometer and elemental imaging system were constructed using a focused ion beam in conjunction with a wavelength-selectable photon detector. Count rates as high as 104/s have been achieved for Al and Si with a 25-keV, 1.5-nA Ga+ beam. For these materials, an unambiguous elemental identification and/or end point can be determined by spectral analysis of the emitted photons. Details of the system and its performance will be discussed. In addition, the increase in yield of electronically excited neutrals from oxides or oxidized surfaces is discussed and the utility of a small gas jet to provide oxygen to the target surface is described. Effects of redeposition are considered as they relate to end-point detection.

Microelectric Discharge Plasma: Characterization and Applications

“…Elemental identification of materials are being carried out using methods such as energy dispersed analysis of X-rays (EDAX) [18], laser-induced plasma spectroscopy [19], laser ionization mass spectroscopy [20], ion beam analysis [21], etc. The above-mentioned methods have several disadvantages such as being expensive, or needing high vacuum, sophisticated operation, and time.…”

Elemental Identification of Materials Using Optical Emission Spectra during Electric Discharge Machining

“…Electric discharge plasma is also used to machine metals and semiconductors and even insulators [4]. Presently, elemental identification material are being carried out using following methods such as chemical analysis [5], x-ray fluorescence holography [6], laser induced plasma spectroscopy [7], laser ionization mass spectroscopy [8], ion beam analysis [9], etc. above said methods having three disadvantages (i) expensive, (ii) need high vaccum, (iii) sophisticated operation and time consuming.…”