Method for forming capacitor element of DRAM

• US 5,508,221 A
• Filed: 12/01/1994
• Issued: 04/16/1996
• Est. Priority Date: 12/02/1993
• Status: Expired due to Fees

• Current Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Original Assignee: NEC Corporation
• Inventors: Kamiyama, Satoshi
• Primary Examiner(s): Nguyen, Tuan H.
• Application Number:
  US08/353,204
• Time in Patent Office: 502 Days
• Field of Search: 437/48, 437/52, 437/60, 437/919, 437/235
• US Class Current: 438/396
• CPC Class Codes: H01L 28/40 Capacitors

Abstract

A stacked capacitor element for a DRAM cell is formed as follows. After a naturally oxidized film on a surface of a polycrystalline silicon film is removed, the polycrystalline silicon film is subjected to a rapid thermal nitriding treatment using lamp annealing so that a capacitor lower electrode of the capacitor element is formed. A tantalum oxide film is deposited on the polycrystalline silicon film and then densified so that a dielectric film of the stacked capacitor element is formed. A conductive film is formed on the tantalum oxide film and patterned. The conductive film is nittided so that a capacitor upper electrode is formed. The capacitor element thus formed enables the suppression of reduction in the capacitance value of the capacitor element of a DRAM and deterioration of the leakage current characteristics.

Claims

1. A method for fabricating a stacked capacitor element of a semiconductor device, said stacked capacitor element having a capacitor lower electrode and a capacitor upper electrode with a dielectric film being interposed therebetween, said method comprising the steps of:

removing a naturally oxidized film on a surface of a polycrystalline silicon film constituting said capacitor lower electrode, and nitriding said surface of the polycrystalline silicon film by a rapid thermal nitriding treatment using lamp annealing;

forming a tantalum oxide film on said polycrystalline silicon film and densifying said tantalum oxide film to form said dielectric film;

forming a conductive film, on said tantalum oxide film, constituting said capacitor upper electrode; and

nitriding said conductive film after having been patterned.

2. The method for fabricating a stacked capacitor element according to claim 1, in which said step of removing the naturally oxidized film is a treatment using one of hydrofluoric anhydride and a diluted hydrofluoric acid.

3. The method for fabricating a stacked capacitor element according to claim 1, in which the step of forming said tantalum oxide film is a chemical vapor deposition using an organic tantalum material.

4. The method for fabricating a stacked capacitor element according to claim 1, in which said densifying treatment of said tantalum oxide film is a treatment carried out in one of an oxygen atmosphere and a nitrous oxide atmosphere using at least one of an electric furnace heat treatment, a rapid thermal treatment using lamp heating, and a plasma assisted heat treatment.

5. The method for fabricating a stacked capacitor element according to claim 1, in which said conductive film constituting said capacitor upper electrode contains at least one of a titanium nitride film, a tungsten nitride film, and a molybden nitride film.

6. The method for fabricating a stacked capacitor element according to claim 1, in which said nitriding treatment of said conductive film is a plasma treatment in one of an ammonium atmosphere, a nitride atmosphere and a nitrous oxide atmosphere.