綠能功率電子元件複層多晶片模組構裝設計與熱管理研究

Abstract

氮化鋁鎵/氮化鎵高電子遷移率電晶體（AlGaN/GaN HEMT）具有寬能隙（約3.4 eV）、高崩潰電壓、高臨界崩潰電場以及高電子飽和漂移速率、高峰值電子速率、高電子飽和速率等優點，因此適用於功率電子方面及高頻通訊方面的應用。氮化鎵(GaN)與碳化矽(SiC)為目前市場上主要產品。其中氮化鎵之熱傳導係數(130W/mk)低於碳化矽(490W/mk)，因此在元件構裝設計須具備良好之熱管理。 為滿足氮化鎵高功率電晶體元件之散熱需求，本文設計了氮化鎵複層基板模組，藉由各材料的熱膨脹係數(Coefficient of thermal expansion)跟氮化鎵接近 ，使得其各層材料之間的側向剪應力降至最低，並藉由多向的散熱途徑，讓氮化鎵功率元件上的熱能可以快速散出，以達到降低晶片溫度的目的。之後進行熱模擬（Ansys Icepak）分析元件探討其熱分佈之情形，再藉由紅外線熱顯影（IR）來跟模擬作對照。

Emerging wide band gap semiconductor gallium nitride (GaN)-based high electron mobility transistor (HEMT) technology has the potential to make lower loss and higher power switching characteristics than those made using traditional silicon (Si) components. Heteroepitaxial Lateral GaN on Si device does not have the high thermal conductivity where high temperature power drive operation is the primary parameter of interest. GaN on Si has difference in the coefficient of thermal expansion (CTE) at the epi interface, which can be an issue during high power cycling. Thus, the packaging design of the component must have good thermal management. Since thermal management is extremely important for GaN high power applications, a hybrid integration of the GaN HEMTs onto a multi-layer AlN/Mo/AlN carrier substrate is proposed. The coefficient of thermal expansion of Mo material is closed to GaN, lateral shear stress can be minimized between the multi-layer GaN module. Effective control over the device temperatures with multi-directional heat dissipate path is necessary to guarantee component performance and reliability. This research uses thermal simulation (Ansys Icepak) to investigate the multi-layer GaN module heat distribution, and in combination with experimental results using Infrared thermography (IR) to verify thermal simulation results.