Overhanging separator for self-defining stacked capacitor

• US 5,796,573 A
• Filed: 05/29/1997
• Issued: 08/18/1998
• Est. Priority Date: 05/29/1997
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ma, William H., Kotecki, David E.
• Primary Examiner(s): Ledynh, Bot L.
• Assistant Examiner(s): Dinkins, Anthony
• Application Number:
  US08/865,533
• Time in Patent Office: 446 Days
• Field of Search: 361/305, 361/303, 361/306.1, 361/301.4, 361/311, 361/312, 361/313, 361/321.1, 361/321.4, 361/321.5, 361/322, 361/512, 438/296, 438/295, 438/305, 438/306, 438/307, 438/240, 438/244, 438/247, 438/250, 438/251, 438/252, 438/253, 438/258, 438/239, 438/238, 257/295, 257/296, 257/301, 257/303, 257/306, 257/309, 257/310, 257/528, 257/532
• US Class Current: 361/321.5
• CPC Class Codes: H10B 12/03 Making the capacitor or connections thereto

Abstract

An overhanging separator structure with a post projecting from a surface which may be a substrate, an underlying layer on the surface, and a separator layer on the underlying layer, with the separator layer overhanging the underlying layer. A discontinuous film is then formed in a single process step having a first portion on the separator layer and a second portion on the post, the discontinuity caused by the overhanging separator layer. The structure is made into a stacked capacitor with the second (post) portion of the discontinuous film being the bottom electrode, by forming a continuous dielectric layer on the bottom electrode and a continuous top electrode layer on the dielectric layer.

Claims

1. An overhanging separator structure useful for creating a self-formed discontinuous film, comprising:

a post projecting from a surface;

an underlying layer on the surface, the underlying layer having a first opening formed therein such that the post is within the first opening and at least a first distance from the underlying layer; and

a separator layer on the underlying layer, the separator layer having a second opening formed therein such that the post is within the second opening and at least a second distance from the separator layer, the second distance greater than zero, and the underlying layer recessed with respect to the separator layer.

2. The structure of claim 1, further comprising a non-patterned discontinuous film having a first portion on the separator layer and a second portion on the post, the non-patterned discontinuous film having a discontinuity substantially in register with the second opening.

3. The structure of claim 2 wherein the structure is a capacitor, and the discontinuous film is a bottom electrode of the capacitor, further comprising:

a dielectric layer on the bottom electrode; and

a continuous top electrode layer on the dielectric layer.

4. The structure of claim 3 wherein the post is conductive.

5. The structure of claim 4 wherein the post is doped polysilicon.

6. The structure of claim 1 wherein the underlying layer is a material selected from the group consisting of oxide, nitride, polysilicon, and polyimide.

7. The structure of claim 1 wherein the underlying layer is an oxide.

8. The structure of claim 1 wherein the separator layer is a material selected from the group consisting of insulators and semiconductors.

9. The structure of claim 1 wherein the separator layer is an insulator.

10. The structure of claim 9 wherein the separator layer is an oxide.

11. The structure of claim 9 wherein the separator layer is a nitride.

12. The structure of claim 9 wherein the separator layer is a material selected from the group consisting of undoped SiO₂, doped SiO₂, SiN, and diamond-like carbon.

13. The structure of claim 3 wherein the bottom electrode is a material selected from the group consisting of noble metals and noble metal oxides.

14. The structure of claim 13 wherein the bottom electrode is platinum.

15. The structure of claim 3 wherein the dielectric layer is a high-dielectric constant material.

16. The structure of claim 15 wherein the dielectric layer is (Ba,Sr)TiO₃.

17. The structure of claim 2 wherein the first distance is at least equal to 2.5 times a thickness of the discontinuous film.

18. The structure of claim 17 wherein the first distance is at least equal to 5 times the thickness of the discontinuous film.

19. The structure of claim 2 wherein the underlying layer has a thickness at least equal to 1.5 times the thickness of the discontinuous film.

20. The structure of claim 19 wherein the underlying layer has a thickness at least equal to 3 times the thickness of the discontinuous film.

21. The structure of claim 2 wherein the second distance is at least equal to 1.5 times the thickness of the discontinuous film.

22. The structure of claim 21 wherein the second distance is at least equal to 3 times the thickness of the discontinuous film.