Recovery of electronic properties in process-damaged ferroelectrics by voltage-cycling

US6171934A · kind A · utility

Assignees

• Symetrix, Inc. · US
• Siemens Aktiengesellschaft · DE

Inventors

• Vikram Joshi · Los Gatos, US
• Narayan Solayappan · Colorado Springs, US
• Walter Hartner · Munich, DE
• Gunther Schindler · Hersbruck, DE

Key dates

• Filing date: Aug 31, 1998
• Grant date: Jan 9, 2001
• Expiry date: Aug 31, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D1/682

Abstract

An integrated circuit is formed containing a metal-oxide ferroelectric thin film. An voltage-cycling recovery process is conducted to reverse the degradation of ferroelectric properties caused by hydrogen. The voltage-cycling recovery process is conducted by applying from 10.sup.4 to 10.sup.11 voltage cycles with a voltage amplitude of from 1 to 15 volts. Conducting voltage-cycling at a higher temperature in the range 30-200.degree. C. enhances recovery. Preferably the metal oxide thin film comprises layered superlattice material. Preferably the layered superlattice material comprises strontium bismuth tantalate or strontium bismuth tantalum niobate. If the integrated circuit manufacture includes a forming-gas anneal, then the voltage-cycling recovery process is performed after the forming-gas anneal. The voltage-cycling recovery process obviates oxygen-recovery annealing, and it allows continued use of conventional hydrogen-rich plasma processes and forming-gas anneals without the risk of permanent damage to the ferroelectric thin film.