Dielectric isolation layer between a nanowire transistor and a substrate
Gate all around semiconductor devices, such as nanowire or nanoribbon devices, are described that include a low dielectric constant (“low-κ”) material disposed between a first nanowire closest to the substrate and the substrate. This configuration enables gate control over all surfaces of the nanowires in a channel region of a semiconductor device via the high-k dielectric material, while also preventing leakage current from the first nanowire into the substrate.
1. An integrated circuit device comprising:
a body over a substrate, the body comprising a first semiconductor material;
a first dielectric layer between the substrate and the body, the first dielectric layer comprising a first dielectric material having a first dielectric constant, and the first dielectric layer having an uppermost surface;
a second dielectric layer having a first portion between the first dielectric layer and the body and a second portion over the body, the second dielectric layer comprising a second dielectric material having a dielectric constant greater than the first dielectric constant;
a gate electrode around the body and in contact with the second dielectric layer;
a source region and a drain region comprising a second semiconductor material having a different chemical composition from the first semiconductor material, the source region and the drain region on opposing sides of the body, and the source region and the drain region directly on the uppermost surface of the first dielectric layer; and
first and second gate spacers, wherein the first gate spacer is between the second dielectric material and one of the source region or drain region, and the second gate spacer is between the second dielectric material and the other of the source region or drain region, and wherein the first and second gate spacers are directly on the uppermost surface of the first dielectric layer.
2. The integrated circuit device of claim 1 , wherein the first dielectric layer is between the substrate and a bottom surface of both the source region and the drain region.
3. The integrated circuit device of claim 1 , wherein first portions of the source region and the drain region are in direct contact with the substrate, and the first dielectric layer is on the substrate between second portions of the source region and the drain region.
4. The integrated circuit device of claim 1 , wherein the body comprises a first body and a second body over the first body.
5. The integrated circuit device of claim 4 , further comprising an additional dielectric layer on and around the second body, the additional dielectric layer comprising the second dielectric material.
6. The integrated circuit device of claim 5 , further comprising a portion of the gate electrode between the additional dielectric layer on the second body and the second dielectric layer on the first body.
7. The integrated circuit device of claim 1 , wherein the first dielectric material comprises silicon and at least one of oxygen and nitrogen.
8. The integrated circuit device of claim 1 , wherein the second dielectric material comprises hafnium and oxygen.
9. The integrated circuit device of claim 1 , wherein the first and second gate spacers each includes multiple portions that are discontinuous from one another.
10. The integrated circuit device of claim 1 , wherein the source region and the drain region comprise at least one source region nanowire and at least one drain region nanowire, respectively.
11. The integrated circuit device of claim 1 , wherein the body comprises one of a nanowire or a nanoribbon.
12. A computing device comprising the integrated circuit device of claim 1 .
13. A method for forming a gate all around semiconductor device comprising:
forming a first sacrificial layer of a first material on a substrate;
forming a second sacrificial layer on the first sacrificial layer, the second sacrificial layer formed from a second material compositionally having a different chemical composition from the first material;
forming a first semiconductor layer on the second sacrificial layer;
forming a dummy gate structure over the first sacrificial layer, the second sacrificial layer, and the first semiconductor layer;
selectively removing the first sacrificial layer while leaving the second sacrificial layer and the first semiconductor layer, the removing forming a first gap defined between the substrate and the second sacrificial layer;
forming a first dielectric layer of a first dielectric material in the first gap, the first dielectric layer having an uppermost surface;
selectively removing the second sacrificial layer to form a second gap defined by the first dielectric layer and the first semiconductor layer;
forming a second dielectric layer of a second dielectric material on a surface of the first semiconductor layer exposed by the second gap; and
forming a source region and a drain region comprising a second semiconductor material having a different chemical composition from the first semiconductor material, the source region and the drain region on opposing sides of the body, and the source and the drain region directly on the uppermost surface of the first dielectric layer.
14. The method of claim 13 , wherein the first dielectric material has a first dielectric constant and the second dielectric material has a second dielectric constant greater than the first dielectric constant.
15. The method of claim 13 , wherein forming the first sacrificial layer, the second sacrificial layer, and the first semiconductor layer comprises epitaxial forming.
16. The method of claim 13 , wherein the first dielectric material prevents leakage current between the first semiconductor layer and the substrate.
17. The method of claim 13 , further comprising:
removing the dummy gate structure; and forming a gate electrode around the first semiconductor layer.
18. The method of claim 13 , further comprising:
forming gate spacers on the dummy gate structure after selectively removing the first sacrificial layer; and
forming the first dielectric material in the first gap during formation of the gate spacers, wherein the gate spacers and the first dielectric layer are both formed from a first dielectric material having a first dielectric constant.