Stable work function for narrow-pitch devices
View Patent ↗A work function setting metal stack includes a configuration of layers including a high dielectric constant layer and a diffusion prevention layer formed on the high dielectric constant layer. An aluminum doped TiC layer has a thickness greater than 5 nm wherein the configuration of layers is employed between two regions as a diffusion barrier to prevent mass diffusion between the two regions.
1. A work function setting metal stack, comprising:
a configuration of layers including
a high dielectric constant layer;
a diffusion prevention layer formed on the high dielectric constant layer; and
an aluminum doped TiC layer having a thickness greater than 5 nm, wherein the configuration of layers is employed between two regions as a diffusion barrier to prevent mass diffusion between the two regions.
2. The stack as recited in claim 1 , wherein the two regions include semiconductor regions.
3. The stack as recited in claim 2 , further comprising an interface layer formed on the semiconductor regions.
4. The stack as recited in claim 2 , wherein the semiconductor regions include adjacent fins for fin field effect transistors.
5. The stack as recited in claim 1 , wherein the diffusion barrier is formed as a gate structure for a field effect transistor.
6. The stack as recited in claim 1 , wherein the diffusion prevention layer includes a TiN layer.
7. The stack as recited in claim 1 , wherein the aluminum doped TiC layer is pinched off to merge with itself between the two regions.
8. The stack as recited in claim 1 , wherein the aluminum doped TiC layer includes an aluminum concentration of between about 20% and about 40%.