Laser annealed dielectric for dual dielectric capacitor

• US 4,437,139 A
• Filed: 12/17/1982
• Issued: 03/13/1984
• Est. Priority Date: 12/17/1982
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Howard, James K.
• Primary Examiner(s): GRIFFIN, DONALD
• Application Number:
  US06/450,629
• Time in Patent Office: 452 Days
• Field of Search: 148/1.5, 361/312, 361/313, 361/323, 29/25.42
• US Class Current: 361/313
• CPC Class Codes: H01G 4/20 using combinations of dielectrics from more than one of groups H01G4/02 - H01G4/06 H01G4/12 takes precedence
• CPC Class Codes: H01L 28/40 Capacitors
• CPC Class Codes: H10B 53/00 Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors
• CPC Class Codes: Y10T 29/435 Solid dielectric type

Abstract

A thin film capacitor having a high dielectric constant and low leakage current includes a dual dielectric structure. The dual dielectric comprises a leakage current blocking first dielectric layer and a high dielectric constant second dielectric layer. The high dielectric constant second dielectric layer is formed by laser annealing a ferroelectric forming titanate or zirconate into a ferroelectric. A leakage current blocking first dielectric layer may also serve as an antireflective coating for the titanate or zirconate layer so that better coupling of the laser energy to the titanate or zirconate layer is obtained.

Claims

1. A method of forming a capacitor on a substrate, comprising the steps of:

depositing a bottom electrode on the substrate;

depositing an amorphous thin film layer of a ferroelectric forming titanate or zirconate on said bottom electrode;

depositing a leakage current preventing dielectric layer on said amorphous thin film layer;

laser annealing said amorphous thin film layer to a crystalline ferroelectric; and

depositing a top electrode on said dielectric layer.

2. The method of claim 1 wherein said bottom electrode comprises a first layer of Zr, Hf or Ta and a second layer of Pt.

3. The method of claim 1 wherein said ferroelectric forming titanate or zirconate is PbTiO₃, BaTiO₃, CaTiO₃, SrTiO₃, PZT or PZLT.

4. The method of claim 1 wherein said leakage current preventing dielectric layer is SiO₂ or Si₃ N₄.

5. The method of claim 1 wherein the leakage current preventing layer depositing step includes the steps of:

depositing an SiO₂ layer on said amorphous thin film layer and depositing an Si₃ N₄ layer on said SiO₂ layer.

6. The method of claim 1 wherein said leakage current preventing dielectric layer is also an antireflective coating for coupling laser energy to said amorphous thin film layer.

7. A method of forming a capacitor on a substrate, comprising the steps of:

depositing a bottom electrode on the substrate;

depositing an amorphous thin film layer of a ferroelectric forming titanate or zirconate on said bottom electrode;

laser annealing said amorphous thin film layer to a crystalline ferroelectric;

depositing a leakage current preventing dielectric layer on said amorphous thin film layer; and

depositing a top electrode on said dielectric layer.

8. The method of claim 7 wherein said bottom electrode comprises a first layer of Zr, Hf or Ta and a second layer of Pt.

9. The method of claim 7 wherein said ferroelectric forming titanate or zirconate is PbTiO₃, BaTiO₃, CaTiO₃, SrTiO₃, PZT or PZLT.

10. The method of claim 7 wherein said leakage current preventing dielectric layer is SiO₂ or Si₃ N₄.

11. The method of claim 7 wherein the leakage current preventing layer depositing step includes the steps of:

depositing an SiO₂ layer on said amorphous thin film layer and depositing an Si₃ N₄ layer on said SiO₂ layer.

12. A method of forming a capacitor on a substrate, comprising the steps of:

depositing a bottom electrode on the substrate;

depositing a leakage current preventing dielectric layer on said bottom electrode;

depositing an amorphous thin film layer of a ferroelectric forming titanate or zirconate on said bottom electrode;

laser annealing said amorphous thin film layer to a crystalline ferroelectric; and

depositing a top electrode on said dielectric layer.

13. The method of claim 12 wherein said bottom electrode comprises a first layer of Zr, Hf or Ta and a second layer of Pt.

14. The method of claim 12 wherein said ferroelectric forming titanate or zirconate is PbTiO₃, BaTiO₃, CaTiO₃, SrTiO₃, PZT or PZLT.

15. The method of claim 12 wherein said leakage current preventing dielectric layer is SiO₂ or Si₃ N₄.

16. The method of claim 12 wherein said amorphous thin film depositing step is followed by the step of depositing an antireflective coating on said amorphous thin film layer for coupling laser energy to said amorphous thin film layer.

17. The method of claim 16 wherein said laser annealing step is followed by the step of removing said antireflective coating from said amorphous thin film layer.

18. A capacitor structure comprised of a dual dielectric between two electrodes wherein said dual dielectric comprises:

a first leakage current preventing dielectric layer adjacent a first one of said electrodes; and

a second dielectric layer between said first dielectric layer and a second one of said electrodes, said second dielectric layer being an amorphous thin film layer of a ferroelectric forming titanate or zirconate which is laser annealed to a crystalline ferroelectric.

19. The structure of claim 18 wherein said bottom electrode comprises a first layer of Zr, Hf or Ta and a second layer of Pt.

20. The structure of claim 18 wherein said ferroelectric forming titanate or zirconate is PbTiO₃, BaTiO₃, CaTiO₃, SrTiO₃, PZT or PZLT.

21. The structure of claim 18 wherein said leakage current preventing dielectric layer is SiO₂ or Si₃ N₄.

22. The structure of claim 18 wherein said leakage current preventing dielectric layer is a dual layer structure comprising an SiO₂ layer and an Si₃ N₄ layer.