Electrical properties of selectively deposited tungsten thin films

Abstract

Tungsten thin films were selectively deposited onto silicon surfaces by a low pressure chemical vapor deposition process utilizing, sequentially, silicon reduction and then hydrogen reduction of WF6. Surface selectivity and conformal coverage of microelectronic structures is demonstrated. X-ray diffraction and Auger analysis indicate the films are well crystallized, with the possibility of a fraction of a percent oxygen content. The room-temperature resistivity is ∼18 μΩ cm, composed of residual and intrinsic contributions of 12 and 6 μΩ cm, respectively. The Hall effect indicates the material is predominantly a hole conductor, with a relatively low Hall mobility that is consistent with the large residual resistivity. Difficulties with a simple interpretation of the Hall effect are discussed.

Control of Selective Tungsten Chemical Vapor Deposition by Monolayer Nitridation of Silicon Surface

“…Bevel etching can be achieved in different ways, but the most reproducible method is wet chemical etching of duplex layers, of which the top layer (T) etches faster than the bottom layer (B) that has to be bevel etched. 2 The slope of the bevel (a) is given by3 sin a = V8/V1 [1] in which V is the etch rate of the relevant layer in rn/s. The most commonly used etchant for ITO is an aqueous solution of HCI and FeCI3.4 As Mo can also be etched in these solutions and is compatible with our device technology, we investigated whether etching ITO with a Mo layer yielded beveled profiles.…”