Semiconductor device and manufacturing method thereof
View Patent ↗A semiconductor fabrication method includes: forming, on a substrate, an epitaxial stack comprising at least one sacrificial epitaxial layer and at least one channel epitaxial layer; forming a fin in the epitaxial stack; forming a sacrificial gate stack on channel regions of the fin; forming gate sidewall spacers on sidewalls of the sacrificial gate stack; performing pre-treatment operations to remove impurities from the at least one sacrificial epitaxial layer; recessing the at least one sacrificial epitaxial layer to form a cavity; forming inner spacer material in the cavity; forming source/drain features; removing the sacrificial gate stack and the at least one sacrificial epitaxial layer in the fins; and forming a metal gate to replace the sacrificial gate stack and the at least one sacrificial epitaxial layer, wherein the inner spacers have sufficient thickness to resist epi damage.
1 . A method, comprising:
forming, on a substrate, an epitaxial stack comprising at least one sacrificial epitaxial layer and at least one channel epitaxial layer;
forming a fin in the epitaxial stack;
forming a sacrificial gate stack on channel regions of the fin;
forming gate sidewall spacers on sidewalls of the sacrificial gate stack;
performing pre-treatment operations to remove impurities from the at least one sacrificial epitaxial layer, wherein performing pre-treatment operations comprise nitridation operations, carbon removal operations, and oxide removal operations;
recessing the at least one sacrificial epitaxial layer to form a cavity; and
forming inner spacer material in the cavity, wherein the inner spacer material has sufficient thickness to resist epi damage.
2 . The method of claim 1 , wherein the at least one sacrificial epitaxial layer has a line width roughness (LWR) that is less than 3 nanometers (nm) after recessing the at least one sacrificial epitaxial layer.
3 . The method of claim 2 , wherein the at least one sacrificial epitaxial layer has a critical dimension (CD) in a range of 5 to 20 nm, and the cavity has a recessed dimension of less than 6 nm.
4 . The method of claim 1 , wherein the impurities comprise one or more of SiO X wherein x is a value from 1 to 3, carbon (C), and GeO y wherein y is value from 1 to 3.
5 . The method of claim 1 , wherein the nitridation operations comprise applying N 2 radicals to the at least one sacrificial epitaxial layer and the at least one channel epitaxial layer.
6 . The method of claim 5 , wherein the carbon removal operations include applying N 2 and H 2 radicals to the at least one sacrificial epitaxial layer and the at least one channel epitaxial layer to remove carbon.
7 . The method of claim 6 , wherein the oxide removal operations include applying a hydrogen fluoride (HF) flush to the at least one sacrificial epitaxial layer and the at least one channel epitaxial layer to remove oxide.
8 . The method of claim 1 , further comprising:
forming source/drain features;
removing the sacrificial gate stack and the at least one sacrificial epitaxial layer in the fin; and
forming a metal gate to replace the sacrificial gate stack and the at least one sacrificial epitaxial layer.
9 . The method of claim 1 , wherein the at least one sacrificial epitaxial layer comprises silicon germanium (SiGe) and the at least one channel epitaxial layer comprises silicon (Si).
10 . A method, comprising:
providing a fin on an epitaxial stack formed over on a substrate and comprising at least one sacrificial epitaxial layer and at least one channel epitaxial layer;
forming a sacrificial gate stack on channel regions of the fin;
forming gate sidewall spacers on sidewalls of the sacrificial gate stack;
performing pre-treatment operations to remove impurities from the at least one sacrificial epitaxial layer, wherein performing pre-treatment operations comprise nitridation operations, carbon removal operations, and oxide removal operations;
recessing the at least one sacrificial epitaxial layer to form a cavity; and
forming inner spacer material in the cavity.
11 . The method of claim 1 , wherein the at least one sacrificial epitaxial layer has a line width roughness (LWR) that is less than 3 nanometers (nm) after recessing the at least one sacrificial epitaxial layer.
12 . The method of claim 2 , wherein the at least one sacrificial epitaxial layer has a critical dimension (CD) in a range of 5 to 20 nm, and the cavity has a recessed dimension of less than 6 nm.
13 . The method of claim 1 , wherein the impurities comprise one or more of SiO x wherein x is a value from 1 to 3, carbon (C), and GeO y wherein y is a value from 1 to 3.
14 . The method of claim 1 , wherein the nitridation operations comprise applying N 2 radicals to the at least one sacrificial epitaxial layer and the at least one channel epitaxial layer.
15 . The method of claim 1 , wherein the carbon removal operations include applying N 2 and H 2 radicals to the at least one sacrificial epitaxial layer and the at least one channel epitaxial layer to remove carbon.
16 . The method of claim 1 , wherein the oxide removal operations include applying a hydrogen fluoride (HF) flush to the at least one sacrificial epitaxial layer and the at least one channel epitaxial layer to remove oxide.
17 . A method, comprising:
forming, on a substrate, an epitaxial stack comprising a plurality of sacrificial epitaxial layers and a plurality of channel epitaxial layers;
forming a fin in the epitaxial stack;
forming a sacrificial gate stack on channel regions of the fin;
forming gate sidewall spacers on sidewalls of the sacrificial gate stack;
performing pre-treatment operations to remove impurities from the plurality of sacrificial epitaxial layers, wherein performing pre-treatment operations comprise nitridation operations, carbon removal operations, and oxide removal operations;
recessing the plurality of sacrificial epitaxial layers to form a plurality of cavities; and
forming inner spacer material in the plurality of cavities.
18 . The method of claim 17 , further comprising:
forming source/drain features;
removing the sacrificial gate stack and the plurality of sacrificial epitaxial layers in the fin; and
forming a metal gate to replace the sacrificial gate stack and the plurality of sacrificial epitaxial layers.
19 . The method of claim 18 , wherein:
the nitridation operations comprise applying N 2 radicals to the plurality of sacrificial epitaxial layers and the plurality of channel epitaxial layers;
the carbon removal operations include applying N 2 and H 2 radicals to the plurality of sacrificial epitaxial layers and the plurality of channel epitaxial layers to remove carbon; and
the oxide removal operations include applying a hydrogen fluoride (HF) flush to the plurality of sacrificial epitaxial layers and the plurality of channel epitaxial layers to remove oxide.
20 . The method of claim 19 , wherein at least one sacrificial epitaxial layer of the plurality of sacrificial epitaxial layers has a line width roughness (LWR) that is less than 3 nanometers (nm) after recessing the plurality of sacrificial epitaxial layers.