AlN介质层对GaN表面生长金刚石钝化膜的影响研究

doi:10.16553/j.cnki.issn1000-985x.2025.0030

摘要/Abstract

摘要： GaN表面生长金刚石钝化膜可用于改善器件传热能力，提升器件功率特性及可靠性。在GaN和金刚石层中间的介质层，对于实现高质量的GaN表面金刚石（Diamond-on-GaN）至关重要。本研究采用原子层沉积（ALD）技术在GaN表面预先沉积了10 nm的晶态/非晶态混合的AlN介质层，并通过氧终端金刚石悬浮液在AlN层上实现了高密度静电自组装播种；随后通过优化的微波等离子体化学气相沉积（MPCVD）工艺再生长约120 nm厚的纳米晶金刚石（NCD）薄膜。表面氧终端调控的纳米金刚石悬浮液可以在AlN介质层表面实现高密度播种，结合梯度甲烷的MPCVD金刚石生长工艺，制备出了具有高结晶度、低粗糙度（Ra=15.2 nm）和低残余应力（0.84 GPa）的NCD薄膜。时域热反射（TDTR）测量表明，NCD薄膜的热导率约为123.85 W·m^-1·K^-1，GaN与NCD之间的有效界面热阻（TBR_eff）为（9.78±0.27） m²·K·GW^-1。透射电子显微镜（TEM）分析表明，AlN介质层有效保护了GaN免受等离子体刻蚀，并实现了金刚石和GaN之间的光滑界面。本研究表明，采用薄的ALD AlN作为在GaN表面生长金刚石的介质层可以与氧终端金刚石籽晶实现静电自组装，从而提高金刚石形核密度，再通过梯度甲烷金刚石沉积工艺，能够在GaN上沉积出高质量的NCD薄膜并降低金刚石与GaN的界面热阻。

关键词: 纳米晶金刚石; GaN; AlN介质层; 热导率; 界面热阻; 原子层沉积; 静电自组装播种

Abstract: The growth of diamond passivation film on GaN surface can be used to improve the heat transfer ability of devices， and enhance the power characteristics and reliability of devices. The dielectric layer between GaN and diamond layers is crucial for achieving high-quality diamond on GaN surface. This study used atomic layer deposition （ALD） technology to pre-deposit a 10 nm crystalline/amorphous mixed AlN dielectric layer on the surface of GaN， and achieved high-density electrostatic self-assembly seeding on the AlN layer through surface terminal controlled diamond suspension； subsequently， an optimized microwave plasma chemical vapor deposition （MPCVD） process was used to grow nanocrystalline diamond（NCD）films with a thickness of approximately 120 nm. The surface oxygen terminal regulated nanodiamond suspension can achieve high-density seeding on the surface of AlN dielectric layer. Combined with gradient methane MPCVD diamond growth process， NCD thin films with high crystallinity， low roughness （Ra=15.2 nm）， and low residual stress （0.84 GPa） were prepared. Time domain thermal reflection（TDTR）measurements indicate that the thermal conductivity of NCD film is approximately 123.85 W·m^-1·K^-1. The effective thermal boundary resistance （TBR_eff） between GaN and NCD is （9.78±0.27） m²·K·GW^-1. Transmission electron microscopy （TEM） analysis shows that， AlN dielectric layer effectively protects GaN from plasma etching and achieves a smooth interface between diamond and GaN. This study shows that using thin ALD AlN as the dielectric layer for growing diamond on GaN surface can achieve electrostatic self-assembly with oxygen terminated diamond seeds， thereby increasing diamond nucleation density. Then， through gradient methane diamond deposition process， high-quality NCD films can be deposited on GaN and the thermal boundary resistance between diamond and GaN can be reduced.

Key words: nanocrystalline diamond; GaN; AlN dielectric layer; thermal conductivity; thermal boundary resistance; atomic layer deposition; electrostatic self-assembly seeding

中图分类号:

TN386

梁礼峰, 郁鑫鑫, 李忠辉, 刘金龙, 李成明, 王鑫华, 魏俊俊. AlN介质层对GaN表面生长金刚石钝化膜的影响研究[J]. 人工晶体学报, 2025, 54(8): 1417-1425.

LIANG Lifeng, YU Xinxin, LI Zhonghui, LIU Jinlong, LI Chengming, WANG Xinhua, WEI Junjun. Effect of AlN Dielectric Layer on Growth of Diamond Passivation Film on GaN Surface[J]. Journal of Synthetic Crystals, 2025, 54(8): 1417-1425.

图/表 8

图1 纳米金刚石钝化层制备流程示意图

Fig.1 Schematic diagram of the preparation process for the passivation layer of nanocrystalline diamond

图2 Un-NDs、O-NDs、AlN的Zeta电位及NDs空气退火前、后FTIR测试结果对比。（a）Un-NDs、O-NDs和AlN的Zeta电位测试结果；（b）NDs在空气退火前、后的FTIR

Fig.2 Comparison of Zeta potentials of Un-NDs， O-NDs， AlN and FTIR test results before and after air annealing of NDs. （a） Zeta potential test results of Un-NDs， O-NDs and AlN；（b） FTIR of NDs before and after air annealing

图3 AlN表面与O-NDs相互吸引并发生静电自组装过程的示意图

Fig.3 Schematic diagram of electrostatic self-assembly process between AlN surface and O-NDs due to mutual attraction

图4 金刚石钝化层表面形貌与成分结构多维度表征（含沉积前AlN表面形貌对比）。（a）金刚石钝化层表面形貌SEM照片；（b）金刚石钝化层表面AFM照片；（c）金刚石沉积前AlN表面形貌SEM照片；（d）金刚石钝化层拉曼光谱

Fig.4 Multi-dimensional characterization of surface morphology and composition structure of diamond passivation layer （including comparison with AlN surface morphology before deposition）. （a） SEM image of the surface morphology of the diamond passivation layer；（b） AFM image of diamond passivation layer surface；（c） SEM image of AlN surface morphology before diamond deposition；（d） Raman spectroscopy of diamond passivation layer

图5 Diamond/GaN界面热导的TDTR表征及层厚依赖性灵敏度分析。（a）TDTR测试数据拟合曲线；（b）Diamond/GaN ITC和各层厚度的灵敏度

Fig.5 TDTR characterization and layer thickness dependent sensitivity analysis of thermal conductivity at Diamond/GaN interface. （a） TDTR test data fitting curve；（b） sensitivity of Diamond/GaN ITC and layer thickness

表1 TDTR测试结果

Table 1 TDTR test results

Layer	Thickness	TC/（W·m^-1·K^-1）	TBR_eff/（m²·K·GW^-1）
Aluminum	100 nm	237	—
Al/Diamond	—	—	21.17
NCD	120 nm	123.85	—
Diamond/GaN	—	—	9.78±0.27
GaN	2 μm	205	—
SiC	500 μm	400	—

图6 衬底表面AlN的HRTEM照片

Fig.6 HRTEM image of AlN on the substrate surface

图7 基于TEM与EDS的Diamond/AlN/GaN复合结构界面微观形貌与元素分布表征。（a）NCD膜断口TEM照片；（b）Diamond/AlN/GaN界面处的TEM照片；（c）Diamond/AlN/GaN界面处的EDS

Fig.7 Characterization of interface microstructure and element distribution of Diamond/AlN/GaN composite structure based on TEM and EDS. （a） TEM image of NCD membrane fracture；（b） TEM image at the Diamond/AlN/GaN interface；（c） EDS at Diamond/AlN/GaN interface

参考文献 28

[1]	CAO L N， WANG J S， HARDEN G， et al. Experimental characterization of impact ionization coefficients for electrons and holes in GaN grown on bulk GaN substrates［J］. Applied Physics Letters， 2018， 112（26）： 262103.
[2]	PENGELLY R S， WOOD S M， MILLIGAN J W， et al. A review of GaN on SiC high electron-mobility power transistors and MMICs［J］. IEEE Transactions on Microwave Theory and Techniques， 2012， 60（6）： 1764-1783.
[3]	BAR-COHEN A， MAURER J J， ALTMAN D H. Embedded cooling for wide bandgap power amplifiers： a review［J］. Journal of Electronic Packaging， 2019， 141（4）： 040803.
[4]	POMEROY J W， UREN M J， LAMBERT B， et al. Operating channel temperature in GaN HEMTs： DC versus RF accelerated life testing［J］. Microelectronics Reliability， 2015， 55（12）： 2505-2510.
[5]	CHU K K， CHAO P C， DIAZ J A， et al. S2-T4： low-temperature substrate bonding technology for high power GaN-on-diamond HEMTs［C］// 2014 Lester Eastman Conference on High Performance Devices （LEC）. August 5-7， 2014， Ithaca， NY， USA. IEEE， 2014： 1-4.
[6]	JESSEN G H， GILLESPIE J K， VIA G D， et al. AlGaN/GaN HEMT on diamond technology demonstration［C］// 2006 IEEE Compound Semiconductor Integrated Circuit Symposium. November 12-15， 2006， San Antonio， TX， USA. IEEE， 2006： 271-274.
[7]	HIRAMA K， KASU M， TANIYASU Y. RF high-power operation of AlGaN/GaN HEMTs epitaxially grown on diamond［J］. IEEE Electron Device Letters， 2012， 33（4）： 513-515.
[8]	ARIVAZHAGAN L， JARNDAL A， NIRMAL D. GaN HEMT on Si substrate with diamond heat spreader for high power applications［J］. Journal of Computational Electronics， 2021， 20（2）： 873-882.
[9]	ZHANG H， GUO Z X， LU Y F. Enhancement of hot spot cooling by capped diamond layer deposition for multifinger AlGaN/GaN HEMTs［J］. IEEE Transactions on Electron Devices， 2020， 67（1）： 47-52.
[10]	SEELMANN E M， MEISEN P， SCHAUDEL F， et al. Heat-spreading diamond films for GaN-based high-power transistor devices［J］. Diamond and Related Materials， 2001， 10（3/4/5/6/7）： 744-749.
[11]	MIRMIRA S R， FLETCHER L S. Review of the thermal conductivity of thin films［J］. Journal of Thermophysics and Heat Transfer， 1998， 12（2）： 121-131.
[12]	SLACK G A， TANZILLI R A， POHL R O， et al. The intrinsic thermal conductivity of AlN［J］. Journal of Physics and Chemistry of Solids， 1987， 48（7）： 641-647.
[13]	YATES L， ANDERSON J， GU X， et al. Low thermal boundary resistance interfaces for GaN-on-diamond devices［J］. ACS Applied Materials & Interfaces， 2018， 10（28）： 24302-24309.
[14]	JIA X， WEI J J， KONG Y C， et al. The influence of dielectric layer on the thermal boundary resistance of GaN-on-diamond substrate［J］. Surface and Interface Analysis， 2019， 51（7）： 783-790.
[15]	ONN D G， WITEK A， QIU Y Z， et al. Some aspects of the thermal conductivity of isotopically enriched diamond single crystals［J］. Physical Review Letters， 1992， 68（18）： 2806-2809. PMID
[16]	ZHU R H， MIAO J Y， LIU J L， et al. High temperature thermal conductivity of free-standing diamond films prepared by DC arc plasma jet CVD［J］. Diamond and Related Materials， 2014， 50： 55-59.
[17]	CHO J， LI Z J， BOZORG G E， et al. Improved thermal interfaces of GaN-diamond composite substrates for HEMT applications［J］. IEEE Transactions on Components， Packaging and Manufacturing Technology， 2013， 3（1）： 79-85.
[18]	BOPPART H， VAN-STRAATEN J， SILVERA I F. Raman spectra of diamond at high pressures［J］. Physical Review B， 1985， 32（2）： 1423-1425. PMID
[19]	MALAKOUTIAN M， FIELD D E， HINES N J， et al. Record-low thermal boundary resistance between diamond and GaN-on-SiC for enabling radiofrequency device cooling［J］. ACS Applied Materials & Interfaces， 2021， 13（50）： 60553-60560.
[20]	MALAKOUTIAN M， LAURENT M A， CHOWDHURY S. A study on the growth window of polycrystalline diamond on Si₃N₄-coated n-polar GaN［J］. Crystals， 2019， 9（10）： 498-498.
[21]	FERRARI A C， ROBERTSON J. Raman spectroscopy of amorphous， nanostructured， diamond-like carbon， and nanodiamond［J］. Philosophical Transactions Series A， Mathematical， Physical， and Engineering Sciences， 2004， 362（1824）： 2477-2512.
[22]	ZENG L Y， PENG H Y， WANG W B， et al. Nanocrystalline diamond films deposited by the hot cathode direct current plasma chemical vapor deposition method with different compositions of CH₄/Ar/H₂ gas mixture［J］. The Journal of Physical Chemistry C， 2008， 112（5）： 1401-1406.
[23]	YANG Q， CHEN W， XIAO C， et al. Low temperature synthesis of diamond thin films through graphite etching in a microwave hydrogen plasma［J］. Carbon， 2005， 43（12）： 2635-2638.
[24]	AJIKUMAR P K， GANESAN K， KUMAR N， et al. Role of microstructure and structural disorder on tribological properties of polycrystalline diamond films［J］. Applied Surface Science， 2019， 469： 10-17.
[25]	KOREPANOV V I， HAMAGUCHI H O， OSAWA E， et al. Carbon structure in nanodiamonds elucidated from Raman spectroscopy［J］. Carbon， 2017， 121： 322-329.
[26]	YOSHIKAWA M， MORI Y， OBATA H， et al. Raman scattering from nanometer-sized diamond［J］. Applied Physics Letters， 1995， 67（5）： 694-696.
[27]	YUAN C， HANUS R， GRAHAM S. A review of thermoreflectance techniques for characterizing wide bandgap semiconductors' thermal properties and devices’ temperatures［J］. Journal of Applied Physics， 2022， 132（22）： 220701.
[28]	SATURDAY L， WILSON L， RETTERER S， et al. Thermal conductivity of nano- and micro-crystalline diamond films studied by photothermal excitation of cantilever structures［J］. Diamond and Related Materials， 2021， 113： 108279.