Though less visible, thin films of TiN are also used in microelectronics, where they serve as a conductive connection between the active device and the metal contacts used to operate the circuit, while acting as a diffusion barrier to block the diffusion of the metal into the silicon. In this context, TiN is classified as a "barrier metal" (electrical resistivity ~ 25 µΩ·cm), even though it is clearly a ceramic from the perspective of chemistry or mechanical behavior. Recent chip design in the 45 nm technology and beyond also makes use of TiN as a "metal" for improved transistor performance. In combination with gate dielectrics (e.g. HfSiO) that have a higher permittivity compared to standard SiO2 the gate length can be scaled down with low leakage, higher drive current and the same or better threshold voltage. Additionally, TiN thin films are currently under consideration for coating zirconium alloys for accident-tolerant nuclear fuels.