Methods of forming multi-Vt III-V TFET devices
The disclosure generally relates to a method for forming multiple III-V Tunnel Field-Effect Transistors (III-V TFETs) microchips in which each TFET has a different threshold voltage (Vt) or work-function. In one embodiment of the disclosure, four TFETs are formed on a substrate. Each TFET has a source, drain and a gate electrode. Each gate electrode is then processed independently to provide a substantially different threshold voltage. Each TFET will have an intrinsic channel.
1. A method to form a device having multiple tunnel field-effect transistors (TFETs) with each TFET having a different work-function, the method comprising:
forming a first, second, third and fourth TFET device, each TFET device having a source electrode, a drain electrode and a gate electrode and each gate electrode having a dipole formation layer and a first gate oxide layer;
forming a first barrier metal layer over the first gate oxide layer for each of the first, second, third and fourth III-V TFET devices;
removing the first barrier metal layer from each of the first III-V TFET device and the second III-V TFET device;
removing the first gate oxide layer from the first III-V TFET device and the second III-V TFET device;
removing the first barrier metal layer from the third III-V TFET device and the fourth III-V TFET device;
depositing a second dielectric layer over each of the first, second, third and fourth III-V TFET devices, the second dielectric layer comprising HFO 2 ;
depositing a second barrier metal layer over each of the first, second, third and fourth III-V TFET devices;
removing the second barrier metal layers from each of the second III-V TFET device and third III-V TFET device;
depositing a third dielectric layer over each of the first, second, third and fourth III-V TFET devices, the third dielectric layer comprising La 2 O 3 ;
annealing each of the first, second, third and fourth III-V TFET devices to diffuse the third dielectric layer into one or more adjacent layers;
removing the third dielectric layer from each of the first, second, third and fourth III-V TFET devices; and
depositing a final metal layer over each of the first, second, third and fourth III-V TFET devices layers to form four TFETs with each TFET having a different threshold voltage.