发明授权
- 专利标题: Use of calcium and strontium dopants to improve retention performance in a PZT ferroelectric film
- 专利标题(中): 使用钙和锶掺杂剂改善PZT铁电薄膜的保留性能
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申请号: US861674申请日: 1997-05-22
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公开(公告)号: US5800683A公开(公告)日: 1998-09-01
- 发明人: Lee Kammerdiner , Tom Davenport , Domokos Hadnagy
- 申请人: Lee Kammerdiner , Tom Davenport , Domokos Hadnagy
- 申请人地址: CO Colorado Springs
- 专利权人: Ramtron International Corporation
- 当前专利权人: Ramtron International Corporation
- 当前专利权人地址: CO Colorado Springs
- 主分类号: C23C14/08
- IPC分类号: C23C14/08 ; H01L21/316 ; C23C14/40
摘要:
A lead zirconate titanate ferroelectric film used as the dielectric layer in a ferroelectric capacitor is doped with calcium and/or strontium, and the lead composition selected to improve data retention performance. The chemical formula for the ferroelectric film is: (Pb.sub.v Ca.sub.w Sr.sub.x La.sub.y)(Zr.sub.z Ti.sub.(1-z))O.sub.3 ; wherein v is ideally between 0.9 and 1.3; w is ideally between 0 and 0.1; x is ideally between 0 and 0.1; y is ideally between 0 and 0.1, and z is ideally between 0 and 0.9. In addition, the chemical composition of the ferroelectric film is further specified in that the measured opposite state charge at a specific time and temperature of the ferroelectric capacitor is greater than eight micro-Coulombs per square centimeter, and the rate of imprint degradation is less than fifteen percent per decade. The method for making the ferroelectric film as the dielectric layer in a ferroelectric capacitor includes sputtering onto a bottom electrode from a target comprising lead zirconate titanate doped with the combination of or subcombinations of calcium, strontium, and lanthanum to a film thickness between 750 Angstroms and 5000 Angstroms. A top electrode is subsequently formed, wherein the top and bottom electrodes are typically noble metals such as platinum. The resultant ferroelectric capacitor is coupled to an integrated MOS transistor to form a ferroelectric memory cell with improved retention performance.
公开/授权文献
- US4140909A Radiation detector 公开/授权日:1979-02-20
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