Joining of Oxidized Aluminum Nitride with Copper and Their Thermal Characteristics

• Main Authors: Chun-Ting Yeh, 葉俊廷
• Other Authors: Wei-Hsing Tuan
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/ffs374

博士 === 國立臺灣大學 === 材料科學與工程學研究所 === 105 === The oxidation behavior of aluminum nitride has been investigated intensively for many years. The oxidation mechanisms that have been proposed are reaction at lower temperatures and diffusion at higher temperatures. In the present study, both the weight gain and the thickness of the oxide layer formed during oxidation were monitored. Detailed microstructure analysis of the oxide surface was also conducted. The analysis indicates that the oxide layer was full of small pores. The formation of pores generates additional surface area to induce further reaction. The reaction mechanism thus controls oxidation at lower temperatures for a long time and at higher temperatures for a short time. The diffusion process takes place simultaneously and becomes dominant when the oxide layer is so thick that the pore channels are fully blocked. To introduce a surface oxide layer onto aluminum nitride substrate helps its subsequent metallization. The pre-oxidized AlN substrate is then bonded to a copper plate. The oxide layer of the substrate is porous, and its presence degrades thermal diffusivity and flexural strength at thicknesses greater than 6 μm. An AlN substrate with a thin oxide layer can bond directly to copper plate at 1070°C. The thin oxide layer remains stable after bonding with copper plate; however, it acts as a barrier to thermal conduction. After joining with copper plates, Cu/AlN bilayers exhibit a thermal conductivity around 120 W/mK at 25°C.