Effect of F doping on capacitance－voltage characteristics of SiCOH low-k films metal－insulator－semiconductor structure

This paper investigates the capacitance--voltage (C--V) characteristics of F doping SiCOH low dielectric constant films metal--insulator--semiconductor structure. The F doping SiCOH films are deposited by decamethylcyclopentasiloxane (DMCPS) and trifluromethane (CHF_3) electron cyclotron resonance plasmas. With the CHF_3/DMCPS flow rate ratio from 0 to 0.52, the positive excursion of C--V curves and the increase of flat-band voltage V_\rm FB from -6.1 V to 32.2 V are obtained. The excursion of C--V curves and the shift of V_\rm FB are related to the change of defects density and type at the Si/SiCOH interface due to the decrease of Si and O concentrations, and the increase of F concentration. At the CHF_3/DMCPS flow rate ratio is 0.12, the compensation of F-bonding dangling bond to Si dangling bond leads to a small V_\rm FB of 2.0 V.