Paramagnetic Defects And Charge Trapping Behavior Of Zro_2 Films Deposited On Germanium By Plasma-enhanced Cvd

摘要

Internal photoemission and magnetic resonance studies have been performed to investigate the charge trapping behavior and chemical nature of defects in ultrathin (～14 nm) high-fc ZrO_2 dielectric films deposited on p-Ge (100) substrates at low temperature (<200 ℃) by plasma-enhanced chemical vapor deposition (PECVD) in a microwave (700 W, 2.45 GHz) plasma at a pressure of ～65 Pa. Both the band and defect-related electron states have been characterized using electron paramagnetic resonance, internal photoemission, capacitance-voltage and current-voltage measurements under UV illumination. Capacitance-voltage and photocurrent-voltage measurements were used to determine the centroid of oxide charge within the high-k gate stack. The observed shifts in photocurrent response of the Al/ZrO_2/GeO_2/p-Ge metal-insulator-semiconductor (MIS) capacitors indicate the location of the centroids to be within the ZrO_2 dielectric near to the gate electrode. Moreover, the measured flat band voltage and photocurrent shifts also indicate a large density of traps in the dielectric. The impact of plasma nitridation on the interfacial quality of the oxides has been investigated. Different N sources, such as NO and NH3, have been used for nitrogen engineering. Oxynitride samples show a lower defect density and trapping over the non-nitrided samples. The charge trapping and detrapping properties of MIS capacitors under stressing in constant current and voltage modes have been investigated in detail.