High Temperature Thermal Conductivity of Amorphous Al₂<scp>O</scp>₃ Thin Films Grown by Low Temperature ALD

Abstract

Al 2 O 3 grown by atomic layer deposition could be proposed as a nonactive layer for back end processes in view of the integration of scaled phase change memory devices. In this paper we report on thermal characterization from 50 to 600 °C of amorphous Al 2 O 3 thin films grown on thermally oxidized silicon substrate at a temperature of 100 °C and capped with a 30 nm thick Pt layer. The effects of low temperature deposition and of a post‐deposition rapid thermal annealing process (RTP) on the thermal properties of the films are investigated using a modulated photo‐thermal radiometry technique coupled with post‐annealing morphological characterizations. Degassing process occurring at high temperature greatly affects the film surface quality, though measurements of the films after RTP show that the thermal conductivity of amorphous Al 2 O 3 increases as a function of temperature from 1.8 W K −1 m −1 at 50 °C to 3.3 W K −1 m −1 at 600 °C. At the same time, the value of the thermal boundary resistance at the Pt‐Al 2 O 3 interface decreases from 1.02 × 10 −7 K m 2 W −1 at 50°C to 4.8 × 10 −8 K m 2 W −1 at 600 °C.