MICROSTRUCTURAL AND ELECTRICAL CHARACTERIZATION OF ION-BEAM-SPUTTEREDPOLYSILICON FILMS FOR MICROELECTRONIC APPLICATIONS

Microcrystalline silicon films of grain size 50-80 nm have been deposi ted by ion beam sputtering from a crystalline silicon target and proce ssed by subsequent annealing. The X-ray diffraction analysis has shown the growth of [420], [200] and [331] principal crystal textures with annealing at temperatures up to 1050-degrees-C. Films of sheet resista nce ranging from tens of ohms to tens of kiloohms per square have been formed by the thermal diffusion of dopants. The electron mobility of phosphorus-doped films varied from 3 to 87 cm2 V-1 s-1 for carrier con centrations of 5 x 10(18) to 10(21) cm-3. A typical boron-doped film s howed a carrier mobility of 38 cm2 V-1 s-1 at a concentration of 3 x 1 0(19) cm-3. Compact resistors of different sizes and aspect ratios hav e been fabricated to test the suitability of the ion-beam-sputtered po lysilicon film as a microelectronic material. The measured current-vol tage characteristics over a wide range of electric field up to 7 kV cm -1 and current density up to 1.3 x 10(6) A cm-2 fit well with the theo retical plots obtained using an improved physical model of polysilicon conduction valid for large bias condition. A TCR of -4 x 10(4) p.p.m. -degrees-C-1 has been obtained for a typical n-type doped resistor wit h a concentration of 8 x 10(19) cm-3.