Diode structure and method for wire-last nanomesh technologies
In one aspect, a method of fabricating an electronic device includes the following steps. An alternating series of device and sacrificial layers are formed in a stack on an SOI wafer. Nanowire bars are etched into the device/sacrificial layers such that each of the device layers in a first portion of the stack and each of the device layers in a second portion of the stack has a source region, a drain region and a plurality of nanowire channels connecting the source region and the drain region. The sacrificial layers are removed from between the nanowire bars. A conformal gate dielectric layer is selectively formed surrounding the nanowire channels in the first portion of the stack which serve as a channel region of a nanomesh FET transistor. Gates are formed surrounding the nanowire channels in the first and second portions of the stack.
1. An electronic device, comprising:
an alternating series of device layers and sacrificial layers in a stack on a semiconductor-on-insulator (SOI) wafer having a SOI layer over a buried oxide (BOX), wherein each of the device layers in at least one first portion and in at least one second portion of the stack has a source region, a drain region and nanowire channels connecting the source region and the drain region;
a conformal gate dielectric layer surrounding the nanowire channels in the at least one first portion of the stack which serve as a channel region of a nanomesh field-effect transistor (FET) transistor;
a first gate on the conformal gate dielectric layer surrounding the nanowire channels in the at least one first portion of the stack which serve as the channel region of the nanomesh FET transistor in a gate all around configuration; and
a second gate surrounding the nanowire channels in the at least one second portion of the stack which serve as a channel region of a nanomesh FET-diode in another gate all around configuration,
wherein the conformal gate dielectric is present only in the nanomesh FET transistor such that: i) the conformal gate dielectric separates the first gate from the nanowire channels in the at least one first portion of the stack which serve as the channel region of the nanomesh FET transistor, and ii) the second gate surrounds and is in direct contact with a portion of each of the nanowire channels in the at least one second portion of the stack which serve as the channel region of the nanomesh FET-diode.
2. The device of claim 1 , further comprising:
at least one shallow trench isolation region isolating the at least one first portion of the stack from the at least one second portion of the stack.
3. The device of claim 1 , wherein the source region and the drain region in each of the device layers in the at least one first portion of the stack is doped.
4. The device of claim 1 , wherein the nanowire channels in each of the device layers in the at least one first portion of the stack is undoped.
5. The device of claim 1 , wherein the source region, the drain region and the nanowire channels in each of the device layers in the at least one second portion of the stack is doped.
6. The device of claim 1 , wherein the conformal gate dielectric layer comprises a high-k material.
7. The device of claim 6 , wherein the conformal gate dielectric layer comprises hafnium oxide or hafnium silicon-oxynitride.
8. The device of claim 6 , wherein the conformal gate dielectric layer comprises hafnium silicon-oxynitride.