INTEGRITY OF SHALLOW JUNCTION CMOS STRUCTURES WITH TI TIN/AL-SI-CU AND TI/TIN/AL-CU CONTACT METALLIZATION/

Shallow junction complementary metal oxide semiconductor (CMOS) struct ures (0.25 and 0.35 mu m depth) were studied using sputter deposited T i/TiN/AlSi-Cu and Ti/TiN/Al-Cu films for contact metallization. Single contact Van de Pauw patterns (to measure the breakdown voltage) as we ll as large junction area structures with multiple contact windows wer e used for electrical measurements. An increase in the RTA temperature used to silicide the contacts increased the Si consumption in the jun ctions and resulted in degradation of junctions yields. The thickness of the Ti layer had a larger influence on the stability of the junctio n than the thickness of the TiN layer (in the range of thicknesses stu died). Al-Si(0.75 wt%)-Cu(0.5 wt%) films are more stable than AI-Cu(0. 5 wt%) films for junction spiking. The AI-Cu films are more reactive, and the interdiffusion of Ti into the Al-Cu films makes the junctions less stable. The annealing temperature and post wafer fabrication is c ritical in maintaining stability of junctions. The junction depths, an d dopants (BF2-p- and As n-implanted) used in forming the junctions af fect the breakdown voltages and junction yields. The BF2 implanted jun ctions are more stable than arsenic implanted junctions.