热源尺寸对AlGaN/GaN HEMT器件热阻的影响机理

Influence Mechanism of the Size of Heat Source on Thermal Resistance of AlGaN/GaN HEMTs

基于CREE公司生产的十条栅指AlGaN/GaN HEMT器件,利用热传导方程,研究了AlGaN/GaN HEMT器件热阻随热源尺寸的变化规律及影响机理,建立了GaN HEMT器件的热传播模型并通过红外测温法结合Sentaurus TCAD模拟仿真的方法验证了模型的准确性。研究发现:热阻随热源尺寸的减小以近似指数的规律增加,随栅宽的减小以反比的规律增加。另外,在芯片尺寸、散热条件、功率密度等条件不变的情况下,栅长从1μm减小到0.05μm时,热阻大约增加80%。对该变化规律从两个方面进行了解释:一方面,热源面积越小,微观尺寸上的散热面积越小,热阻越大;另外,热源尺寸的减小会引起热源处热容的减小,产生的热量是一定的,热阻与温升成正比,因此对应的热阻增加。

Based on the AlGaN/GaN high electron mobility transistor（ HEMT） device,which has ten fingers made by CREE company,the change law and influence mechanism between thermal resistance and the size of heat source by equation of heat conduction were studied.Thermal propagation model of the GaN HEMT devices was established.The validity of the model was verified by infrared image method and simulation using the Sentaurus TCAD.It is found that thermal resistance increases in the approximate exponent with the decrease in the size of heat source.Thermal resistance rises with the decrease in gate width by the tendency of the approximate exponential and inverse correlation respectively.With the chip size,heat emission condition and power density remain unchanged,the gate length reduces from 1 μm to 0.05 μm,the thermal resistance increases by about 80%.There are two explanations for this phenomenon： firstly,the smaller the heat source area,the smaller the cooling area in micro scale,and the greater the thermal resistance.In addition,the decrease of the heat source size will diminish the chip heat capacity,the heat generated by heat source is constant.Thermal resistance of chip in proportion to temperature rising,so thermal resistance increased.