Vertical stacked nanosheet cmos transistors with different work function metals

A semiconductor device comprising at least:

• a first nanosheet stack for a first device;
• a second nanosheet stack for a second device, wherein the second nanosheet stack is disposed on top of the first nanosheet stack;
• and
• a gate structure wrapping around the first nanosheet stack and the second nanosheet stack, wherein the gate structure comprises
• a gate dielectric layer;
• a first work function layer in contact with at least a first portion of the gate dielectric layer;
• a second work function layer in contact with at least second portion of the gate dielectric layer surrounding nanosheet layers of the second nanosheet stack;
• and
• a gate conductor layer formed in contact with the second work function layer.

A method for forming a semiconductor device, the method comprising at least:

• forming a structure comprising at least a first nanosheet stack including a first set of alternating nanosheet and sacrificial layers for a first device, a second nanosheet stack disposed over the first nanosheet stack and including a second set of alternating nanosheet and sacrificial layers for a second device, a disposable gate structure formed in contact with the second nanosheet stack, and a gate spacer wrapping the disposable gate structure;
• removing the disposable gate structure and sacrificial layers of the first and second nanosheet stacks thereby forming a plurality of cavities;
• forming a conformal gate dielectric layer in the plurality cavities and surrounding at least portions of each nanosheet layer of the first and second nanosheet stacks;
• forming a first conformal work function layer in contact with the gate dielectric layer;
• removing, without using a mask, portions of the first conformal work function layer from at least the second nanosheet stack and sidewalls of the first nanosheet stack;
• forming a second conformal work function layer on exposed portions of the gate dielectric layer;
• and
• forming a gate conductive layer in contact with the second conformal work function layer.