Patent ID: 7989342

Claim:
A method for fabricating a diffusion-barrier cap ( 138 ) on a Cu-containing interconnect element ( 102 ) that has crystallites ( 116 to 122 ) of at least two different crystal orientations in an interconnect stack ( 100 ) of a semiconductor device, comprising: selectively incorporating Si into only a first set of crystallites ( 116 , 120 ) with at least one first crystal orientation, employing first process conditions, and subsequently selectively forming a first adhesion-layer portion ( 128 ) comprising CuSi and a first diffusion-barrier-layer portion ( 132 ) only on the first set of crystallites, thus forming a first barrier-cap portion ( 138 . 1 ) and leaving a second set of crystallites ( 118 , 122 ) of the interconnect element ( 102 ) with at least one second crystal orientation exposed, and subsequently selectively incorporating Si into only the second set of crystallites ( 118 , 122 ), employing second process conditions that differ from the first process conditions, and forming a second barrier-cap portion ( 138 . 2 ) comprising a Si-containing second diffusion-barrier layer portion ( 136 ) on the second set of crystallites ( 118 , 122 ) of the interconnect element.