Nanosheet channel-to-source and drain isolation

摘要

A method and structures are used to fabricate a nanosheet semiconductor device. Nanosheet fins including nanosheet stacks including alternating silicon (Si) layers and silicon germanium (SiGe) layers are formed on a substrate and etched to define a first end and a second end along a first axis between which each nanosheet fin extends parallel to every other nanosheet fin. The SiGe layers are undercut in the nanosheet stacks at the first end and the second end to form divots, and a dielectric is deposited in the divots. The SiGe layers between the Si layers are removed before forming source and drain regions of the nanosheet semiconductor device such that there are gaps between the Si layers of each nanosheet stack, and the dielectric anchors the Si layers. The gaps are filled with an oxide that is removed after removing the dummy gate and prior to forming the replacement gate.

主权项

1. A method of fabricating a nanosheet semiconductor device, the method comprising:
forming nanosheet fins including nanosheet stacks comprising alternating silicon (Si) layers and silicon germanium (SiGe) layers on a substrate; etching each nanosheet fin to define a first end and a second end along a first axis between which each nanosheet fin extends parallel to every other nanosheet fin; undercutting the SiGe layers in the nanosheet stacks at the first end and the second end to form divots at the first end and the second end; depositing a dielectric at the first end and the second end, wherein the depositing includes depositing the dielectric in the divots at the first end and the second end; removing the SiGe layers between the Si layers such that there are gaps between the Si layers of each nanosheet stack and the dielectric anchors the Si layers at the first end and the second end, wherein the removing the SiGe layers precedes forming source and drain regions of the nanosheet semiconductor device; filling the gaps with an oxide to form second nanosheet stacks comprising alternating layers of the Si and the oxide prior to forming a dummy gate above the nanosheet stacks; and removing the oxide after removal of the dummy gate and prior to replacement with a replacement gate.