Characteristics of MOSFET's Fabricated in SPE Grown Polysilicon

Currently various SOI and 3D schemes are being evaluated to enable novel 'MOS processes. Solid Phase Epitaxy (SPE) appears to be a potentially very valuable approach because of its simplicity. Amorphous silicon or polycrystalline silicon is deposited uniformly over selectively oxidized silicon substrate as shown in Fig. 1. Conventional furnace annealing first grows the film epitaxially in the seed area which would, under favorable conditions, extend laterally to produce SOI. W4hile lateral extension on oxide would permit a wide variety of applications, it must be pointed out that even a successful SPE growth in the seed area alone is useful for some select applications which can benefit from oxide isolation of passive circuit components. In such cases MIOSFETs can be built in a minimum geometry SPE grown polysilicon in the seed area and passive elements in polysilicon on the oxide. M1aterial studies of SPE silicon have previously been made [1,2,3] but no electrical data is available. It is the purpose of this paper to demonstrate that using conventional processing steps high quality MOSFETs can be built in SPE grown polysilicon in the seed area.