Patent ID: 8679923
Filing Date: 2014-03-25
Classification: H01L

Abstract:
1. A method for forming metal gates, comprising: providing a substrate with a first region and a second region; forming a first dummy gate structure and a second dummy gate structure within the first region and the second region, respectively, wherein the first dummy gate structure includes a first dummy gate and the second dummy gate structure includes a second dummy gate; forming an interlayer dielectric layer on the substrate exposing the first dummy gate structure and the second dummy gate structure; removing the first dummy gate of the first dummy gate structure to form a first opening; forming a first work function layer within the first region over the interlayer dielectric layer and the first opening, and within the second region over the second dummy gate; forming a first sacrificial layer on the first work function layer; exposing the second region by removing a portion of the first sacrificial layer and a portion of the first work function layer from the second region to leave a remaining first sacrificial layer and a remaining of the first work function layer in the first region on top of the interlayer dielectric layer; removing the second dummy gate of the second dummy gate structure to form a second opening; forming a second work function layer within the second region overlaying the second opening, over the interlayer dielectric layer in the second region, and over the remaining first sacrificial layer in the first region comprising the first opening; forming a second sacrificial layer on the second work function layer; removing a portion of the second sacrificial layer and a portion of the second work function layer from the first region to expose the remaining first sacrificial layer in the first region on top of the interlayer dielectric layer and to leave a remaining second sacrificial layer on a remaining second working function layer in the second region on top of the interlayer dielectric layer; exposing the first opening comprising a portion of the remaining first work function layer and exposing the second opening comprising a portion of the remaining second work function layer by removing the remaining first sacrificial layer and the remaining second sacrificial layer; forming a metal layer on the first work function layer and the second work function layer; and performing a CMP process to the metal layer, the first work function layer and the second work function layer to form a first metal gate and a second metal gate.