A comparison of gold and platinum sputtered coatings for scanning electron microscopy

Abstract

It is widely accepted that thin conducting films of noble metals have the desirable properties of high electron emission and high resistance to corrosion which fit them for use as specimen coatings for scanning electron microscopy. However, although Au and its alloys with Pd are regularly used for this purpose, deposited by either evaporation or sputtering, the use of Pt has apparently been ignored. The high evaporation temperature of this metal (2090°C against 1350°C for Au) makes its controlled evaporation inconvenient, but the recent commercial introduction of simple sputter coaters, coupled with developments in Pt plating technology, have made the sputtering of Pt on to SEM specimens a practical proposition. A comparison of the properties of sputtered coatings of Au and Pt has therefore been made; results given below show that satisfactory coatings may be made with Pt as conveniently as with Au, and that in some respects the Pt coatings are superior.