Method of forming self-aligned contacts using a replacement metal gate process in a semiconductor device

摘要

Techniques disclosed herein provide a gate pitch scaling solution for creating source/drain contacts in a replacement metal gate fabrication scheme. Such techniques provide a self-aligned contact process that protects gate electrodes from shorts due to etching from misaligned patterns. Techniques herein provide a dual layer cap formed by making a semi conformal material deposition over a non-planar topography of RMG formation structures, and using selective etching and planarization to yield a dual layer protective cap that does not excessively increase an aspect ratio.

主权项

1. A method of forming self-aligned contacts in a semiconductor device, the method comprising:
receiving a substrate having a first structure of a first material composition and a Second structure of a second material composition, the second structure being formed immediately adjacent to the first structure, the first structure and second structure being of different heights such that together the first structure and the second structure defining a first topography that is non-planar at an upper surface thereof; depositing a first layer on the first topography, the first layer being partially conformal resulting in the first layer defining a second topography, the first layer defining a valley over the first structure and forming a peak over the second structure; depositing a second layer on the first layer, the second layer being sufficiently thick to fill the defined valley and cover the peak of the second topography; planarizing the second layer down to the first layer above the second structure such that the peak in the first layer is exposed while the defined valley remains filled with the second layer; and etching exposed portions of the first layer down until reaching the second structure beneath the first layer, the second layer in the defined valley functioning as a hard mask that impedes etching of the first layer above the first structure relative to etching of the first layer above the second structure.