Multi-gate device and method of fabrication thereof
First Claim
1. A method comprising:
- forming a first fin and a second fin in a first region and a second region, respectively, over a substrate, the first fin having a first source/drain region and a first channel region, the second fin having a second source/drain region and a second channel region, both of the first fin and the second fin are formed of a stack of epitaxial layers that includes first epitaxial layers having a first composition interposed by second epitaxial layers having a second composition;
forming dummy gate stacks over the first channel region and the second channel region;
removing the second epitaxial layers from a portion of the first fin to form first gaps in the first source/drain region;
after removing the second epitaxial layers from a portion of the first fin to form the first gaps in the first source/drain region, forming a spacer layer on sidewalls of the dummy gate stacks with a dielectric material while filling the first gaps with the dielectric material;
forming a third epitaxial layer on at least two surfaces of each of the first epitaxial layers in the first source/drain region to form a first source/drain feature while the dielectric material fills the first gaps;
forming a fourth epitaxial layer over the second fin in the second source/drain region to form a second source/drain feature;
forming a dielectric layer over the first source/drain feature and the second source/drain feature;
after the forming the dielectric layer over the first and second source/drain features, removing the second epitaxial layers from a portion of the first fin in the first channel region to form second gaps between two adjacent first epitaxial layer;
after removing the second epitaxial layers, forming a first gate stack over the first fin in the first channel region, wherein first gate stack fills in the second gaps in the first channel region; and
forming a second gate stack over the second fin in the second channel region, wherein the second gate stack is disposed on sidewalls of the first and second epitaxial layers of the second fin in the second channel region.
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Abstract
A semiconductor includes a first transistor and a second transistor. The first transistor includes a first and a second epitaxial layer, formed of a first semiconductor material. The second epitaxial layer is disposed over the first epitaxial layer. The first transistor also includes a first gate dielectric layer surrounds the first and second epitaxial layers and extends from a top surface of the first epitaxial layer to a bottom surface of the second epitaxial layer and a first metal gate layer surrounding the first gate dielectric layer. The second transistor includes a third epitaxial layer formed of the first semiconductor material and a fourth epitaxial layer disposed directly on the third epitaxial layer and formed of a second semiconductor. The second transistor also includes a second gate dielectric layer disposed over the third and fourth epitaxial layers and a second metal gate layer disposed over the second gate dielectric layer.
99 Citations
20 Claims
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1. A method comprising:
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forming a first fin and a second fin in a first region and a second region, respectively, over a substrate, the first fin having a first source/drain region and a first channel region, the second fin having a second source/drain region and a second channel region, both of the first fin and the second fin are formed of a stack of epitaxial layers that includes first epitaxial layers having a first composition interposed by second epitaxial layers having a second composition; forming dummy gate stacks over the first channel region and the second channel region; removing the second epitaxial layers from a portion of the first fin to form first gaps in the first source/drain region; after removing the second epitaxial layers from a portion of the first fin to form the first gaps in the first source/drain region, forming a spacer layer on sidewalls of the dummy gate stacks with a dielectric material while filling the first gaps with the dielectric material; forming a third epitaxial layer on at least two surfaces of each of the first epitaxial layers in the first source/drain region to form a first source/drain feature while the dielectric material fills the first gaps; forming a fourth epitaxial layer over the second fin in the second source/drain region to form a second source/drain feature; forming a dielectric layer over the first source/drain feature and the second source/drain feature; after the forming the dielectric layer over the first and second source/drain features, removing the second epitaxial layers from a portion of the first fin in the first channel region to form second gaps between two adjacent first epitaxial layer; after removing the second epitaxial layers, forming a first gate stack over the first fin in the first channel region, wherein first gate stack fills in the second gaps in the first channel region; and forming a second gate stack over the second fin in the second channel region, wherein the second gate stack is disposed on sidewalls of the first and second epitaxial layers of the second fin in the second channel region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method comprising:
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forming a fin in a device region over a substrate, the fin having a source/drain region and a channel region, the fin being formed of a stack of epitaxial layers that includes first epitaxial layers having a first composition interposed by second epitaxial layers having a second composition; forming a dummy gate stack over the channel region of the fin such that sidewalls of the fin are covered by the dummy gate stack; removing the second epitaxial layers from the source/drain region of the fin to form first gaps in the source/drain region; after removing the second epitaxial layers from the source/drain region of the fin to form the first gaps in the source/drain region, forming a spacer layer on sidewalls of the dummy gate stack with a dielectric material while filling the first gaps with the dielectric material; forming a third epitaxial layer on at least two surfaces of each of the first epitaxial layers in the source/drain region to form a source/drain feature while the dielectric material fills the first gaps; forming a dielectric layer over the source/drain feature; removing the dummy gate stack from the channel region; removing the second epitaxial layers from the channel region of the fin in the channel region to form second gaps; and forming a gate stack over the channel region of the fin with a gate material, wherein the gate material fills the second gaps in the channel region. - View Dependent Claims (14, 15, 16, 17)
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18. A method comprising:
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forming a fin in a device region over a substrate, the fin having a source/drain region and a channel region, the fin being formed of a stack of epitaxial layers that includes first epitaxial layers having a first composition interposed by second epitaxial layers having a second composition; forming a dummy gate stack over a top surface and sidewalls of the fin in the channel region; forming a third epitaxial layer on at least two surfaces of the stack of epitaxial layers in the source/drain region to form a source/drain; performing a planarization process to expose top surfaces of the dummy gate stack; removing the dummy gate stack from the channel region; selectively removing a topmost first epitaxial layer over the channel region of the fin to expose a topmost second epitaxial layer; and after selectively removing the topmost first epitaxial layer, forming a gate stack over the channel region of the fin, wherein the gate stack is disposed on sidewalls of the first and second epitaxial layers of the fin in the channel region and directly on the exposed topmost second epitaxial layer of the fin. - View Dependent Claims (19, 20)
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Specification