Improvement of Voltage Linearity and Leakage Current of MIM Capacitors With Atomic Layer Deposited Ti-Doped ZrO2 Insulators

MIM capacitors have been widely investigated as passive devices in integrated circuits. In this work, Ti-doped ZrO2 (ZTO) thin films prepared by plasma-enhanced atomic layer deposition (PEALD) are explored as the dielectrics of MIM capacitors. First, modulation of capacitance density and quadratic voltage coefficient of capacitance ( $\alpha {)}$ is achieved for the MIM capacitors by adjusting the ALD cycle ratio of TiO2/ZrO2 (Ti/Zr). The $\alpha $ -value exhibits a decreasing trend with increasing the content of Ti, even down to a negative value. In terms of Ti/Zr=1/2, the capacitor shows a minimum $\vert \alpha \vert $ value of 219 ppm/ $\text{V}^{{2}}$ , accompanied by a capacitance density of 11.64 fF/ $\mu \text{m}^{{2}}$ . Furthermore, an additional $\text{O}_{{2}}$ plasma treatment (5 min) of the ZTO dielectric significantly reduces the leakage current by three orders of magnitude; meanwhile, the $\alpha $ -value decreases by $\sim $ 42%. In a word, the optimized capacitor demonstrates good electrical properties including a capacitance density of 12.21 fF/ $\mu \text{m}^{{2}}$ , $\alpha $ of 128 ppm/ $\text{V}^{{2}}$ , leakage current of ${7}.{85} \times {10} ^{-{7}}$ A/cm2 at 1 V, and temperature coefficient of capacitance (TCC) of 194 ppm/ $\text{V}^{{2}}$ . This is related to the passivation of oxygen vacancies in ZTO caused by $\text{O}_{{2}}$ plasma treatment.