Improved Tunability of BEoL-integrated Hafnium Zirconium Oxide Varactors for mmWave Applications

The discovery of ferroelectricity in hafnium oxide has gained significant attention due to its detrimental role in modern microelectronics [1] . If doped with zirconium, Hf x Zr 1-x O 2 (HZO), it crystallizes into an orthorhombic ferroelectric phase at sufficiently lower temperatures [3] , which is important to meet the requirements on maximum anneal temperature for conventional Back-End-of-Line (BEoL) processes. This makes HZO an ideal candidate for use as a thin-film varactor with applications in RF and mmWave networks.