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US006855971B2
(12) United States Patent ao) Patent No.: us 6,855,971 B2
Basceri et al. (45) Date of Patent: Feb. 15,2005
(54) HAZE-FREE BST FILMS
(75) Inventors: Cem Basceri, Boise, ID (US); Gurtej Sandhu, Boise, ID (US)
(73) Assignee: Micron Technology, Inc., Boise, ID (US)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 210 days.
(21) Appl. No.: 09/971,955
(22) Filed: Oct. 4, 2001
(65) Prior Publication Data
US 2002/0033497 Al Mar. 21, 2002
Related U.S. Application Data
(62) Division of application No. 09/382,753, filed on Aug. 25, 1999, now Pat. No. 6,319,764.
(51) Int. CI.7 H01L 27/08; H01L 29/76;
H01L 29/94; H01L 31/119
(52) U.S. CI 257/295; 257/306
(58) Field of Search 257/295-310;
438/3, 241-254
(56) References Cited
U.S. PATENT DOCUMENTS
5,185,689 A 2/1993 Maniar
5,335,138 A 8/1994 Sandhu et al.
5,406,445 A 4/1995 Fujii et al.
5,506,166 A 4/1996 Sandhu et al.
5,581,436 A 12/1996 Summerfelt et al.
(List continued on next page.)
FOREIGN PATENT DOCUMENTS
Described herein is a method for producing a haze-lree (Ba, Sr)Ti03 (BST) film, and devices incorporating the same. In one embodiment, the BST film is made haze-lree by depositing the film with a substantially uniform desired crystal orientation, for example, (100), prelerably by forming the film by metal-organic chemical vapor deposition at a temperature greater than about 580° C. at a rate ol less than about 80 A/min, to result in a film having about 50 to 53.5 atomic percent titanium. In another embodiment, where the BST film serves as a capacitor for a DRAM memory cell, a desired {100} orientation is induced by depositing the bottom electrode over a nucleation layer ol NiO, which gives the bottom electrode a prelerential {100} orientation. BST is then grown over the {100} oriented bottom electrode also with a {100} orientation. A nucleation layer ol materials such as Ti, Nb and Mn can also be provided over the bottom electrode and beneath the BST film to induce smooth, haze-lree BST growth. Haze-lree BST film can also be lavored by forming the bottom electrode at high temperatures close to those used for BST deposition, and without a vacuum break between the bottom electrode and BST deposition.
