Investigation of Scaling Limits for PECVD SiN and ALD HfO2/Al2O3 Integrated MIM Capacitors

Abstract

Scalability of MIM capacitors to higher capacitance densities is commonly limited by increasing leakage current and dielectric breakdown as the dielectric film is being made thinner. MIM Capacitors using PECVD SiN with up to 4fF/μm2 capacitance density and high-k ALD HfO2/Al2O3 dielectrics with up 12 fF/μm2 capacitance density have been developed and characterized for VLSI RF-CMOS and BiCMOS technologies with up to 5.5 V power supply voltage. Linearity, matching, and reliability were found to be generally degraded with increased capacitance density. Improved linearity could be achieved with dielectric film optimization and stacking of capacitors. TDDB lifetime of PE-CVD SiN MIM capacitors with 2.7 fF/µm2 and of ALD high-k MIM capacitors with capacitance densities from 5 fF/µm2 to 7.4 fF/μm2 show suitability for applications up to 3.6V using a conservative reliability model.