Focused ion beam insulator deposition

Focused ion beam (FIB) induced deposition of insulating films from TEOS, a SiO2 precursor, is reported. Deposition was typically carried out using a 30 kV beam of Ga+ ions with a range of ion beam currents from 40 to 2000 pA. The deposition rate was measured as a function of beam current density into the scanned area and scan period, with a typical rate of 0.3 mu m(3)/nC being noted. An important application of the FIB is to repair integrated circuits enabling faster debugging and shorter design cycles. With the continuing trend toward devices containing more interconnect layers having narrower tracks and spaces, it is becoming increasingly difficult to access lower metal levels when they are completely covered by wide upper tracks. Localized FIB insulator deposition enables contact to lower level metal without first removing large areas of the upper metal layers which would otherwise be required. In such structures isolation resistances of more than 15 G Omega have been measured between the metal layers, corresponding to resistivities greater than 10(8) Omega cm, with a breakdown voltage for the material in the range of 20 to greater than 100 V/mu m. (C) 1995 American Vacuum Society.