The "performance code" of advanced manufacturing processes: Rare earths make transistors "more energy-efficient and fast

When the manufacturing process enters the sub-7-nanometer range, the thickness of the gate dielectric layer of transistors is less than 5 nanometers - equivalent to 30 atoms lined up side by side. At this point, the traditional silicon dioxide (SiO₂) dielectric will leak due to the "tunneling effect", wasting power like a "leaky battery". The addition of rare earth elements has enabled semiconductors to break through this physical limit.

The high-k dielectric process is the core of the solution. Currently, the mainstream high-k material is hafnium oxide (HfO₂), but the dielectric constant (k value) of pure HfO₂ is about 25, which is still insufficient to support the 3-nanometer process. Therefore, two rare earth elements, lanthanum (La) and yttrium (Y), have been "invited" into the dielectric layer: a few angstroms thick layer of lanthanum oxide (La₂O₃) is deposited on the surface of HfO₂. After high-temperature annealing, lanthanum ions will diffuse to the interface between the dielectric and silicon, forming "interface dipoles", which is like installing a "voltage regulator" for the transistor, reducing the threshold voltage by more than 0.2V. This means that under the same performance, the power consumption of the chip can be reduced by 30%; under the same power consumption, the switching speed can be increased by 20%.

This "rare earth empowerment" is also extending to more cutting-edge fields. The thulium (Tm) laser developed by the Lawrence Livermore National Laboratory in the United States uses thulium ions to generate 2μm lasers, which is expected to increase the efficiency of EUV light sources from the current 0.02% to 0.2% - this means that the power consumption of lithography machines can be reduced by 90%, and the cost can be halved. In the 5G RF field, aluminum scandium nitride (AlScN) films, due to the addition of scandium (Sc), have a piezoelectric performance three times that of pure aluminum nitride (AlN), making them the "performance king" of BAW filters and directly determining whether mobile phones can achieve high-speed communication in the 5G high-frequency band.