Effects of annealing temperature on the characteristics of ALD-deposited HfO₂ in MIM capacitors

We have investigated the annealing effects of HfO₂ films deposited by an atomic layer deposition (ALD) method on the electrical and physical properties in the Si/SiO₂/Pt/ALD-HfO₂/Pd metal-insulator-metal (MIM) capacitors. If the annealing temperature for HfO₂ films was restricted below 500 °C, an annealing step using a rapid thermal processor (RTP) improves the electrical properties such as the dissipation factor and the dielectric constant. On the other hand, annealing at 700 °C degrades the electrical characteristics in general; the dissipation factor increases over the frequency range of 1∼4 MHz, and the leakage current increases up to 2 orders at the low electric field regions. We found that the degradation of electrical properties is due to the grain growth in the HfO₂ film (i.e., poly-crystallization of the film) by the high temperature annealing processing. We suggested that the annealing temperature must be restricted below 500 °C to obtain the high quality high-k film for the MIM capacitors.