Gate structures in transistors and method of forming same
In some embodiments, a method includes forming a plurality of nanostructures over a substrate; etching the plurality of nanostructures to form first recesses; forming source/drain regions in the first recesses; removing first nanostructures of the plurality of nanostructures leaving second nanostructures of the plurality of nanostructures; depositing a gate dielectric over and around the second nanostructures; performing an aluminum treatment on the gate dielectric; depositing a first conductive material over and around the gate dielectric; performing a fluorine treatment on the first conductive material; and depositing a second conductive material over and around the first conductive material.
1 . A device, comprising:
a first nanostructure extending between a source region and a drain region;
a second nanostructure over the first nanostructure;
a gate dielectric over and around the first nanostructure and the second nanostructure;
an aluminum residue over the gate dielectric, the aluminum residue being non-continuous;
a work function metal (WFM) layer over the gate dielectric and the aluminum residue, the WFM layer comprising fluorine, a first portion of the WFM layer being disposed around the first nanostructure, a second portion of the WFM layer being disposed around the second nanostructure; and
a conductive layer disposed over the WFM layer, a first portion of the conductive layer being disposed around the first nanostructure, a second portion of the conductive layer being disposed around the second nanostructure.
2 . The device of claim 1 further comprising a metal residue being directly interposed between the WFM layer and the conductive layer.
3 . The device of claim 2 , wherein each of the WFM layer and the gate dielectric comprises fluorine.
4 . The device of claim 1 , wherein the first portion of the conductive layer physically contacts the second portion of the conductive layer.
5 . The device of claim 1 , wherein the WFM layer is a p-type WFM layer.
6 . The device of claim 1 , wherein the gate dielectric comprises a first gate dielectric layer and a second gate dielectric layer.
7 . The device of claim 6 , wherein a region interposed between the second gate dielectric layer and the WFM layer comprises a concentration of aluminum in a range from about 0.3% to about 10%.
8 . A transistor, comprising:
a first dielectric material disposed over a first nanostructure;
a first metal residue disposed over the first dielectric material;
a first conductive material disposed over the first dielectric material, the first conductive material being in physical contact with the first dielectric material and the first metal residue;
a second conductive material disposed over the first conductive material;
a third conductive material disposed over the second conductive material, the third conductive material having the same composition as the first conductive material;
a second metal residue disposed over the third conductive material, the second metal residue having the same composition as the first metal residue;
a second dielectric material disposed over the second metal residue, the second dielectric material having the same composition as the first dielectric material; and
a second nanostructure disposed over the second dielectric material.
9 . The transistor of claim 8 further comprising:
a third metal residue interposed between the first conductive material and the second conductive material; and
a fourth metal residue interposed between the second conductive material and the third conductive material, the fourth metal residue having the same composition as the third metal residue.
10 . The transistor of claim 9 , wherein the third metal residue comprises tungsten.
11 . The transistor of claim 8 , wherein each of the first dielectric material, the first conductive material, the third conductive material, and the second dielectric material comprises fluorine.
12 . The transistor of claim 8 , wherein the first metal residue comprises aluminum.
13 . The transistor of claim 8 , wherein the first dielectric material comprises hafnium oxide.
14 . The transistor of claim 13 , wherein a ratio of fluorine to hafnium in the first dielectric material ranges from 0.07 to 0.4.
15 . A semiconductor device, comprising:
an interfacial oxide disposed over and around a first nanostructure;
a high-k gate dielectric over the interfacial oxide, the high-k gate dielectric comprising a first metal, oxygen, and fluorine;
a first metal layer over the high-k gate dielectric, the first metal layer having incomplete coverage over the high-k gate dielectric, the first metal layer comprising a second metal, the second metal being different from the first metal, the first metal layer being non-continuous;
a first conductive material over the first metal layer, the first conductive material comprising a third metal, the third metal being different from the first metal and the second metal;
a second metal layer over the first conductive material, the second metal layer having incomplete coverage over the first conductive material, the second metal layer comprising a fourth metal and fluorine, the fourth metal being different from the first metal, the second metal, and the third metal; and
a second conductive material over the second metal layer, the second conductive material comprising a fifth metal, the fifth metal being different from the first metal, the second metal, and the fourth metal.
16 . The semiconductor device of claim 15 , wherein the second metal layer is non-continuous.
17 . The semiconductor device of claim 15 , wherein the first metal is hafnium, wherein the second metal is aluminum, and wherein the third metal is titanium.
18 . The semiconductor device of claim 17 , wherein the fourth metal is tungsten, and wherein the fifth metal is either titanium or tantalum.
19 . The semiconductor device of claim 15 , wherein the first conductive material comprises a fluorine concentration ranging from 5% to 25%.
20 . The semiconductor device of claim 15 , wherein a plane at an interface between the high-k gate dielectric and the first conductive material comprises a concentration of aluminum in a range from about 0.3% to about 10%.