ABSTRACTPolycrystalline silicon films have been amorphized by implantation with 100keV Ga ions of doses 0.3 and 6×1015cm−2. These films were subsequently recrystallized using either a furnace for longer times lower temperature (∼30 mins, 600° C) or rapid thermal processing (RTP) for shorter times higher temperatures ( ≤ 30 sec, 800° C, 900° C) in an endeavour to suppress any long range movement of the Ga during the anneal phase. It is found that for both the furnace and RTP for temperatures ≤ 800°C no significant movement is observed and that the lower temperature anneal for the highest dose produces the highest electrical conductivity. By contrast however, annealing at 900° C, even though the initial conductivity is higher than for any other anneal we observe a significant reduction with time and extremely rapid movement of the dopant species throughout the original poly layer. An initial rationale for this behaviour is proposed in terms of a liquid phase transformation during annealing.
An electrothermal model of memory switching in vertical polycrystalline silicon structures