High performance TaYOx-based MIM capacitors
TaYOx-based metalinsulatormetal (MIM) capacitors with excellent electrical properties have been fabricated. Ultra-thin TaYOx films in the thickness range of 1530nm (EOT?2.44.7nm) were deposited on Au/SiO2 (100nm)/Si (100) structures by rf-magnetron co-sputtering of Ta2O5 and Y2O3 targets. TaYOx layers were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) to examine the composition and crystallinity. An atomic percentage of Ta:Y=58.32:41.67 was confirmed from the EDX analysis while XRD revealed an amorphous phase (up to 500C) during rapid thermal annealing. Besides, a high capacitance density of ?3.75.4fF/?m2 at 10kHz (?r?21), a low value of VCC (voltage coefficients of capacitance, ? and ?) have been achieved. Also, a highly stable temperature coefficient of capacitance, TCC has been obtained. Capacitance degradation phenomena in TaYOx-based MIM capacitors under constant current stressing (CCS at 20nA) have been studied. It is observed that degradation depends strongly on the dielectric thickness and a dielectric breakdown voltage of 35MV/cm was found for TaYOx films. The maximum energy storage density was estimated to be ?5.69J/cm3. Post deposition annealing (PDA) in O2 ambient at 400C has been performed and further improvement in device reliability and electrical performances has been achieved.
tayox mim capacitor high-k dielectric rf sputter deposition