Enhanced stress transfer in an interlayer dielectric by using an additional stress layer above a dual stress liner in a semiconductor device
By forming an additional stressed dielectric material after patterning dielectric liners of different intrinsic stress, a significant increase of performance in transistors may be obtained while substantially not contributing to patterning non-uniformities during the formation of respective contact openings in highly scaled semiconductor devices. The additional dielectric layer may be provided with any type of intrinsic stress, irrespective of the previously selected patterning sequence.
1. A method, comprising:
forming a first stress-inducing layer above a plurality of first transistors and a plurality of second transistors formed above a substrate, said first stress-inducing layer generating a first type of stress;
removing said first-stress-inducing layer from above said plurality of second transistors;
forming a second stress-inducing layer above said plurality of first transistors and said plurality of second transistors after removing said first-stress-inducing layer from above said plurality of second transistors, said second stress-inducing layer generating a second type of stress other than said first type of stress;
removing said first-stress-inducing layer from above said plurality of first transistors; and
forming a third stress-inducing layer above said portions of said first and second stress-inducing layers formed above said pluralities of first and second transistors, said third stress-inducing layer generating one of said first and second types of stress.
2. The method of claim 1 , wherein a thickness of said first stress-inducing layer is different from a thickness of said second stress-inducing layer.
3. The method of claim 1 , further comprising removing a portion of said third stress-inducing layer from above one of said pluralities of first and second transistors wherein a combined thickness of said third stress-inducing layer plus the one of the first and second stress-inducing layers over which the third stress-inducing layer remains is approximately equal to a thickness of the other of the first and second stress-inducing layers over which the third stress-inducing layer was removed.
4. The method of claim 1 , further comprising:
removing a portion of said third stress-inducing layer from above one of said pluralities of first and second transistors;
forming a fourth stress-inducing layer generating a different type of stress relative to said third stress-inducing layer above said third stress-inducing layer and said pluralities of first and second transistors after removing said portion of said third-stress-inducing layer.
5. The method of claim 4 , further comprising removing a portion of said fourth stress-inducing layer from above said third stress-inducing layer, wherein a combined thickness of said third stress-inducing layer plus the one of the first and second stress-inducing layers over which the third stress-inducing layer remains is approximately equal to a thickness of the other of the first and second stress-inducing layers over which the third stress-inducing layer was removed plus a thickness of said fourth stress-inducing layer.
6. The method of claim 1 , further comprising reducing said stress generated by said third stress-inducing layer selectively above said first stress-inducing layer when said third stress-inducing layer generates said second type of stress, and reducing said stress generated by said third stress-inducing layer selectively above said second stress-inducing layer when said third stress-inducing layer generates said first type of stress.
7. The method of claim 1 , wherein reducing said stress induced by said third stress-inducing layer comprises performing an ion implantation process while masking one of the first and second plurality of transistors.
8. The method of claim 5 , further comprising removing a portion of said fourth-stress-inducing layer from above said one of said pluralities of first and second transistors from above which said third stress-inducing layer was removed while removing said portion of said fourth stress-inducing layer from above said third stress-inducing layer.
9. A method, comprising:
forming a plurality of stress-inducing layers above a plurality of first transistors and a plurality of second transistors formed above a substrate;
selectively removing portions of said stress-inducing layers from above said plurality of first transistors or said plurality of second transistors, where at least two of said plurality of stress-inducing layers remain over at least one of said plurality of first transistors or said plurality of second transistors, and a combined thickness of said stress-inducing layers remaining above said first plurality of transistors is approximately equal to a combined thickness of said stress-inducing layers remaining above said plurality of second transistors;
forming an interlayer dielectric layer above said stress-inducing layers remaining above said pluralities of first and second transistors; and
forming a first contact opening in said interlayer dielectric layer above at least one of said plurality of first transistors and a second contact opening in said interlayer dielectric layer above at least one of said plurality of second transistors.