Implementation of long-channel thick-oxide devices in vertical transistor flow
A method for fabricating a semiconductor structure is provided that includes the steps of: forming a structure including a substrate, a counter-doped layer on the substrate, and a heavily doped source contact layer on a side of the counter-doped layer opposite the substrate; and forming an oxide layer on a side of the heavily doped source contact layer opposite the counter-doped layer, wherein the oxide layer has a vertical dimension that is a difference between a length of a long channel thick oxide device and a length of a short channel non-thick oxide device.
1. A semiconductor structure comprising:
a substrate;
a first vertical transistor device having a first region on a doped source contact layer of the substrate and having a first drain; and
a second vertical transistor device having a second region on the doped source contact layer of the substrate and having a second drain;
wherein the first vertical transistor device comprises a short vertical channel, and the second vertical transistor device comprises a long vertical channel having a vertical length greater than the short vertical channel.
2. The semiconductor structure of claim 1 , wherein the long vertical channel comprises an oxide having an equivalent oxide thickness of about 1 to about 5 nanometers.
3. The semiconductor structure of claim 1 , further comprising a metal gate in contact with sidewalls of a first epitaxially grown channel layer, a top surface of the first spacer layer, and a bottom surface of the second spacer layer:
wherein the first spacer layer and the second spacer layer are separate and do not touch.
4. A semiconductor structure comprising:
a source contact layer formed on a substrate, the source contact layer comprising a first thickness in a first region of the substrate and a second thickness in a second region of the substrate, the first thickness greater than the second thickness;
a short channel, non-thick oxide vertical transistor device formed on a surface of the source contact layer in the first region of the substrate; and
a long channel, thick oxide vertical transistor device formed on a surface of the source contact layer in the second region of the substrate.