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US006972430B2
(12) United States Patent ao) Patent No.: us 6,972,430 B2
Casagrande et al. (45) Date of Patent: Dec. 6,2005
Page 2
5,970,336 A 10/1999 Wolstenholme et al 438/238
6,031,287 A * 2/2000 Harshfield 257/734
6,238,946 Bl * 5/2001 Ziegler 438/50
6,512,241 Bl 1/2003 Lai 257/4
6,613,604 B2 9/2003 Maimon et al 438/95
(75) Inventors: Giulio Casagrande, Vignate (IT);
Roberto Bez, Milan (IT); Fabio
Pellizzer, Follina (IT)
(73) Assignees: STMicroelectronics S.r.l., Agrate
Brianza (IT); OVONYX Inc., Boise, ID
(US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 27 days.
(21) Appl. No.: 10/371,154
(22) Filed: Feb. 20, 2003
(65) Prior Publication Data
US 2004/0012009 Al Jan. 22, 2004
Related U.S. Application Data
(63) Continuation-in-part of application No. 10/313,991, filed on Dec. 5, 2002.
(30) Foreign Application Priority Data
Feb. 20, 2002 (EP) 02425088
(51) Int. CI.7 H01L 45/00
(52) U.S. CI 257/4; 257/2; 257/3
(58) Field of Search 257/2-5, 296,
257/314-316, E27.004; 365/148
(56) References Cited
U.S. PATENT DOCUMENTS
5,789,277 A 8/1998 Zahorik et al 438/95
5,814,527 A 9/1998 Wolstenholme et al 438/5
5,952,671 A 9/1999 Reinberg et al 257/3
An electronic semiconductor device has a sublithographic contact area between a first conductive region and a second conductive region. The first conductive region is cup-shaped and has vertical walls which extend, in top plan view, along a closed line of elongated shape. One of the walls of the first conductive region forms a first thin portion and has a first dimension in a first direction. The second conductive region has a second thin portion having a second sublithographic dimension in a second direction transverse to the first dimension. The first and the second conductive regions are in direct electrical contact at their thin portions and form the sublithographic contact area. The elongated shape is chosen between rectangular and oval elongated in the first direction. Thereby, the dimensions of the contact area remain approximately constant even in presence of a small misalignment between the masks defining the conductive regions.
16 Claims, 12 Drawing Sheets
