金刚石衬底上GaN HEMT沟道温度建模:各向异性且非均匀热导率的影响  

Analysis of Channel Temperature in GaN on Diamond HEMT: Effect of Anisotropic and Inhomogeneous Thermal Conductivity

作　　者：李姚 郑子轩[1,3] 蒲红斌 LI Yao;ZHENG Zixuan;PU Hongbin(Department of Electronic Engineering,Xi’an University of Technology,Xi’an 710048,China;Key Laboratory of Wide Band-gap Semiconductor Materials,Ministry of Education,Xidian University,Xi’an 710071,China;Xi’an Key Laboratory of Power Electronic Devices and High Efficiency Power Conversion,Xi’an 710048,China)

机构地区：[1]西安理工大学电子工程系,西安710048 [2]西安电子科技大学宽带隙半导体材料教育部重点实验室,西安710071 [3]西安市电力电子器件与高效电能变换重点实验室,西安710048

出　　处：《人工晶体学报》2022年第2期222-228,共7页Journal of Synthetic Crystals

基　　金：宽禁带半导体材料教育部重点实验室开放基金(Kdxkf2019-01);陕西省教育厅科研计划(21JK0809)。

摘　　要：为了改善GaN HEMT的自热效应,集成高热导率的金刚石衬底有助于增强器件有源区的热量耗散。然而,化学气相淀积(CVD)生长的多晶金刚石(PCD)具有柱状晶粒结构,导致了各向异性的材料热导率,且其热导率值与生长厚度有关。为此,通过建模金刚石生长过程中晶粒尺寸的演变过程,计算了金刚石沿面内和截面方向的热导率。基于该PCD热导率模型,利用计入材料非线性热导率的GaN器件热阻解析模型,计算得到了GaN HEMT沟道温度的波动范围,并分析了其与器件结构(栅长、栅宽、栅间距、衬底厚度)和功耗的依赖关系。最后,通过与有限元(FEM)仿真结果对比,分区域提取了GaN HEMT器件中PCD衬底的有效热导率,分别为260~310 W/(m·K)和1250~1450 W/(m·K)。本文的计算为预测金刚石衬底上GaN HEMT器件的沟道温度提供了快速、有效的方法。To improve the self-heating effect in GaN HEMT, integrating diamond substrate with high thermal conductivity is an effective way for heat dissipation in active region of device. However, columnar grain structures in polycrystalline diamond(PCD) grown by chemical vapor deposition(CVD) cause anisotropic and thickness dependence thermal conductivity of PCD. Therefore, the evolution of diamond grain size during growth was modeled to compute the PCD thermal conductivity along the in-plane and cross-plane directions. Based on the above PCD thermal conductivity model, the limitations of channel temperature in GaN HEMT were derived by computing the analytical model of GaN thermal resistance incorporating the nonlinear thermal conductivity, whose variations were studied with the device structure(gate length, gate width, gate spacing and substrate thickness) and power dissipation. Finally, by comparing with the verified finite element model(FEM) simulation results, two effective thermal conductivities of PCD were extracted, which are 260~310 W/(m·K) and 1 250~1 450 W/(m·K). This calculations provide a fast and effective way to estimate the channel temperature in GaN HEMT on diamond substrate.

关 键 词：GaN HEMT 沟道温度 各向异性 热导率 解析模型 器件热阻 

分 类 号：TN386[电子电信—物理电子学]