Diffusion Furnace Dopant Activation Matching Through a Ramped Temperature Idle

摘要

Significant non-uniform 'time at temperature' or Dt variation is observed across a horizontal furnace load in diffusion batch processes. Non uniform activation of dopants is observed in 800°C, short duration processes with high mobility dopant species. Dt matching across the furnace is obtained by changing the temperature zone set points at furnace idle prior to pushing and processing a full wafer batch. A ramped idle temperature ranging 120°C across the furnace improves activation uniformity. Boron implanted test wafers show an 85% reduction in activation non uniformity' across the furnace when using a ramped idle.