Aln Coatings with High Thermal Conductivity and Excellent Electrical Insulation Properties for Thermal Management Devices

Thermal conductive materials with low dielectric constant under high current frequencies and good electrical insulation properties play an important role in large-scale integrated circuits. The application of high thermal conductivity Cu in the field of integrated circuit packaging is limited due to the lack of insulation performance. In this paper, the AlN coatings were prepared on the Cu substrates (AlN/Cu system) using multi-arc ion plating to maintain the high thermal conductivity and obtain excellent insulation performance for the first time. The microstructure, thermal conductivity and electrical performances of the AlN/Cu systems were adjusted by changing the duty cycle of the coatings. The results show that the (002) preferred orientation of hcp-AlN phase appeared in all the coatings. High duty cycle reduced the (002) preferred orientation degree. With the increase of duty cycle, the growth structure of the coatings was changed (layer-columnar-layer), which induced the grain and particles size of the coatings first increasing and then decreasing. AlN/Cu systems under different duty cycles significantly improved the thermal conductivity of Cu substrate due to the surface defects of Cu filled by AlN coatings. All the coatings showed high electrical resistivity (higher than (2.44±0.01)×10 10 Ω·cm) and low dielectric loss (0.006~0.24). At high current frequencies (100 kHz~2000 kHz), with the increase of duty cycle, the dielectric constant of the AlN coatings first reduced and then improved. The minimum dielectric constant (5.8) of the coating was obtained at 50% duty cycle. The AlN/Cu systems in this paper have high thermal conductivity, excellently electrical insulation and dielectric properties, meeting the application requirements in large-scale integrated circuit packaging.