Fixed Charge Reduction and Tunneling in Stacked Dielectrics

aluminum oxide;stacked dielectrics;hafnium oxide;high-k;fixed charge;tunneling

Hinkle, Christopher ; Gerald Lucovsky, Committee Chair,Jon-Paul Maria, Committee Member,Robert Nemanich, Committee Member,Hans Hallen, Committee Member,Hinkle, Christopher ; Gerald Lucovsky ; Committee Chair ; Jon-Paul Maria ; Committee Member ; Robert Nemanich ; Committee Member ; Hans Hallen ; Committee Member

University:North Carolina State University

关键词: aluminum oxide;    stacked dielectrics;    hafnium oxide;    high-k;    fixed charge;    tunneling;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/5623/etd.pdf?sequence=1&isAllowed=y

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【 摘 要 】

Stacked gate dielectrics using high-k materials were deposited using a RPECVD method.Aluminum oxide, hafnium oxide, hafnium silicate, nitrided films of each of the above, and multi-layer stacks of the above as well as silicon dioxide were deposited.These films were analyzed using AES, XPS, NRA, RBS, SIMS, XAS, cathodoluminescence, spectroscopic ellipsometry, capacitance-voltage, and current-voltage techniques.Fixed charge was found to be present in all high-k films and was practically impossible to reduce in a significant way.Nitridation of the films was unsuccessful at reducing the charge, but was helpful in enhancing some electrical measurements.Sandwich stack structures showed enhanced tunneling which led to a novel approach of calculating the E[subscript b]-m[subscript eff] product in the transmission probability equation.This tunneling also gives some clues as to which types of gate stacks cannot be used in technology.Gate stacks containing an HfO₂ layer below an Al₂O₃ layer were studied and also showed enhanced tunneling.Analysis of this tunneling found two significant trapping sites in the HfO₂ layer, one located ~0.5 eV below the HfO₂ conduction band offset and the other located in the Si bandgap.Fixed charge reduction was again expected in these laminates, but again remained despite theoretical predictions.