Abstract

As aggressive scaling of CMOS circuits continues, gate oxide thickness is reduced in order to maintain control of ever shrinking channel lengths. Current cutting edge transistors are using a gate oxide thickness below 20Å, approaching a regime where direct, or quantum, tunneling is the primary leakage mechanism. Below ~16Å, leakage becomes too great for use in MOS transistors. There are short-term fixes in place, however the industry road map indicates the need for an alternative to SiO2 within five years. Among the leading candidates is Zirconium Oxide (ZrO2).

ZrO2 was investigated as a possible replacement for Si02 in MOS devices. A statistically designed experiment was utilized to optimize processing parameters. MOS capacitors were used as a test vehicle. Leakage less than 200pA, breakdown strength greater than 8MV/cm, and relative permittivity greater than 7, have been demonstrated. ZrO2 gate dielectric, PMOS transistors have been fabricated with l-V characteristics comparable to transistors with a SiO2 gate dielectric, as shown in the l-V plot below. An initial investigation into a damascene Copper/Titanium gate stack, utilizing ZrO2 as a gate dielectric, was also been performed. Capacitors fabricated in this manner exhibited similar reliability results as capacitors fabricated using conventional processes.

Graph: lDS vs. VDS at different VGS, for a PMOS transistor with a ZrO2 gate dielectric. Graph is difficult to read.

Library of Congress Subject Headings

Metal oxide semiconductors, Complementary--Design and construction; Zirconium oxide--Electric properties

Publication Date

6-30-2006

Document Type

Thesis

Student Type

Graduate

Degree Name

Microelectronic Engineering (MS)

Department, Program, or Center

Microelectronic Engineering (KGCOE)

Advisor

Michael A. Jackson

Advisor/Committee Member

Santosh K. Kurinec

Advisor/Committee Member

Karl D. Hirschman

Comments

Physical copy available from RIT's Wallace Library at TK7871.99.M44 L43 2006

Campus

RIT – Main Campus

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