(12) United States Patent ao) Patent No.: us 7,008,828 B2
Ono et al. (45) Date of Patent: Mar. 7,2006
(54) METHOD OF MANUFACTURING SEMICONDUCTOR DEVICE
(75) Inventors: Koji Ono, Atsugi (JP); Hideomi
Suzawa, Atsugi (JP); Tatsuya Arao,
(73) Assignee: Semiconductor Energy Laboratory
Co., Ltd., Kanagawa-ken (JP)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 121 days.
(21) Appl. No.: 10/645,516
(22) Filed: Aug. 22, 2003
(65) Prior Publication Data
US 2004/0053451 Al Mar. 18, 2004
Related U.S. Application Data
(62) Division of application No. 09/714,891, filed on Nov. 17, 2000, now Pat. No. 6,646,287.
(30) Foreign Application Priority Data
Nov. 19, 1999 (JP) 11-330174
(51) Int. CI.
H01L 21/84 (2006.01)
(52) U.S. CI 438/149; 438/163; 438/301
(58) Field of Classification Search 438/149,
438/163,164, 514, 517 See application file for complete search history.
In a semiconductor device, typically an active matrix display device, the structure of TFTs arranged in the respective circuits are made suitable in accordance with the function of the circuit, and along with improving the operating characteristics and the reliability of the semiconductor device, the manufacturing cost is reduced and the yield is increased by reducing the number of process steps. A semiconductor device has a semiconductor layer, an insulating film formed contacting the semiconductor layer, and a gate electrode having a tapered portion on the insulating film, in the semiconductor device, the semiconductor layer has a channel forming region, a first impurity region for forming a source region or a drain region and containing a single conductivity type impurity element, and a second impurity region for forming an LDD region contacting the channel forming region, a portion of the second impurity region is formed overlapping a gate electrode, and the concentration of the single conductivity type impurity element contained in the second impurity region becomes larger with distance from the channel forming region.
13 Claims, 30 Drawing Sheets