功率電子元件封裝熱阻量測法改良及量測重複性分析

Abstract

AlGaN/GaN功率晶體，相較於傳統以矽為主體的功率元件，具有高的電子移動率、高崩潰電壓的特徵，適合操作在高功率、高頻率下。但是由於AlGaN/GaN功率晶體為水平結構且熱傳導特性差，需要良好的封裝熱管理。本研究使用電性參數估測法，藉由量測元件電性參數曲線來推估通道溫度，和傳統破壞性量測方法相比，電性參數估測法擁有易於量測、不受元件結構影響、重現性高、不會破壞元件等等優點，而且量測出來的溫度為元件通道溫度而非表面的溫度。現今對於功率元件散熱能力的主要評估標準為結殼熱阻(Rthjc)，藉由量測元件在定電流加熱下隨時間變化的電性參數推估出AlGaN/GaN功率晶體通道溫度變化，計算出暫態熱阻曲線，參考JESD 51-14 Transient Dual Interface Method(TDIM)方法求出元件結殼熱阻，其值越小代表元件散熱能力越佳。 本研究發展以加熱曲線取代傳統冷卻曲線的量測方法可以大幅降低量測所需時間。在任何實驗中，實驗結果的準確度以外重複性也是非常重要的，同樣的條件下能得出同樣的結果才能使人信服。本研究從實驗的環境、實驗儀器的架構和資料的處理等等盡可能的排除不確定的因素，使得量測多種不同封裝形式的功率元件皆可得到足夠好的重複性。 元件內部結構資訊對於元件開發和可靠度測試皆很重要，本研究使用new network identification by deconvolution(NNID)極大地提升結構函數解析度和準確度，可以觀察到元件內部各層結構個別的熱阻資訊，並在多種不同元件上進行測試皆有不錯的結果，未來在元件開發和可靠度分析上有很大的幫助。

The high power dissipation and poor thermal conductivity for AlGaN/GaN HEMT power device can result in a serious self-heating effect on the topside surface due to lateral topologies, which will need a well thermal management. This paper proposes a simple, non-invasive, high repeatability and no restricts by the device package method that can evaluate the static and transient thermal resistance constitution. This method is based on the transient thermal resistance by the measurement of the temperature sensitivity electrical parameter for the AlGaN/GaN HEMT. Nowadays, the most important evaluation criterion of the cooling capacity of the power device is the junction-to-case thermal resistance. This study developed a heating curve to replace the traditional cooling curve of the measurement method can significantly reduce the time required for measurement. Also improved the transient dual interface method (TDIM) from JESD 51-14 standard for less error and high measurement repeatability. The information of the internal structures of the power device is very important for the device development and reliability. This paper propose a new, higher resolution and more accurate method called new network identification by deconvolution(NNID). This method has the ability to evaluate the individual thermal resistance of all the internal structures of the power device, and it is illustrated by a number of examples