US 9,812,366 B2
Method of tuning work function for a semiconductor device
Yu-Lien Huang, Hsinchu County (TW); and Tung Ying Lee, Hsinchu (TW)
Assigned to Taiwan Semiconductor Manufacturing Company, Ltd., Hsin-Chu (TW)
Filed by Taiwan Semiconductor Manufacturing Company, Ltd., Hsin-Chu (TW)
Filed on Aug. 15, 2014, as Appl. No. 14/460,469.
Prior Publication US 2016/0049301 A1, Feb. 18, 2016
Int. Cl. H01L 21/8234 (2006.01); H01L 21/8238 (2006.01); H01L 21/28 (2006.01); H01L 29/49 (2006.01); H01L 29/66 (2006.01)
CPC H01L 21/82345 (2013.01) [H01L 21/28088 (2013.01); H01L 21/823828 (2013.01); H01L 21/823842 (2013.01); H01L 29/4966 (2013.01); H01L 29/66545 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A method for fabricating a semiconductor device, the method comprising:
forming a metal layer over a substrate;
determining a first distribution of injecting angles (DIA) for tuning a work function of the metal layer, wherein the first DIA is one of a band-type continuous probability distribution having a range from a first angle to a second angle and a multimodal probability distribution having at least a first peak at a third angle and a second peak at a fourth angle;
modifying the work function of the metal layer by applying a first multi-angle-doping (MAD) process to a first region of the metal layer, the first region defining a first work function, according to the first DIA that includes:
injecting, from an emission point of a doping species source, a first plurality of doping species beams towards the metal layer while the substrate remains at a first orientation, wherein a first plurality of injecting angles of the first plurality of doping species beams are in accordance with the first DIA;
determining a second DIA for tuning the work function of the metal layer, wherein the second DIA is the other of the band-type continuous probability distribution and the multimodal probability distribution; and
after applying the first MAD process, applying a second MAD process to the first region of the metal layer according to the second DIA, wherein the second MAD process includes:
injecting, from the emission point of the doping species source, a second plurality of doping species beams towards the metal layer while the substrate remains at the first orientation, wherein a second plurality of injecting angles of the second plurality of doping species beams are in accordance with the second DIA.