Improved properties of MIM capacitors using ALD Al2O3 by multi-temperature technique

A different strategy to form dielectric thin films using atomic layer deposition is proposed, where the dielectric stack consists of three layers in which the middle layer is deposited at a higher temperature than the top and bottom layer. This multi-temperature dielectric stack in metal-insulator-metal capacitor offers improved electrical properties compared to a dielectric film deposited at a single temperature. A multilayer 40 nm thick Al₂O₃ deposited with temperature and thickness sequence of 80 °C - 10 nm, 150 °C - 20 nm, and 80 °C - 10 nm offers reduced leakage current density by more than one order of magnitude compared to that for a 40 nm Al₂O₃ deposited at 150°C, and offers higher capacitance density compared to that for 40 nm Al₂O₃ deposited at 80 °C, and low values of voltage coefficients of capacitance. The changes in the capacitance density and leakage current are found to be strongly dependent on the various roughness values in the devices.