Electrochemical capacitance-voltage characterization of plasma-doped ultra-shallow junctions

Abstract

Ultra-shallow Si p⁺n junctions formed by plasma doping are characterized by electrochemical capacitance-voltage (ECV). By comparing ECV results with those of secondary ion mass spectroscopy (SIMS), it is found that the dopant concentration profiles in heavily-doped p⁺ layer as well as junction depths measured by ECV are in good agreement with those measured by SIMS. However, the ECV measurement of dopant concentration in the underlying lightly doped n-type substrate is significantly influenced by the upper heavily-doped layer. The ECV technique is also easy to control and reproduce. The ECV results of ultra-shallow junctions (USJ) formed by plasma doping followed by different annealing processes show that ECV is capable of reliably characterizing a Si USJ with junction depth as low as 10 nm, and dopant concentration up to 10²¹ cm^-3. Also, its depth resolution can be as fine as 1 nm. Therefore, it shows great potential in application for characterizing USJ in the sub-65 nm technology node CMOS devices.

Keywords

electrochemical capacitance-voltage, ultra-shallow junction, dopant concentration