Analysis of the ohmic contacts of Ti/Al/Ni/Au to AlGaN/GaN HEMTs by the multi-step annealing process

Yan, Wei; Zhang, Renping; Yandong, Du; Han, Wei; Yang, Fuhua

doi:10.1088/1674-4926/33/6/064005

Cited by 12 publications

(10 citation statements)

References 9 publications

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“…То есть процессы взаимной диффузии и образования ин-терметаллидных соединений предваряют процессы роста дендритов. Эти эксперименты подтверждают идеи, заявленные в работах [9,17], о положительном влиянии предварительного отжига при температу-рах 400-600 °С на результаты окончательной стадии отжига при высоких температурах 800-900 °С. Та-ким образом, в двухслойной металлизации титан-алюминий при отжиге в течение 300 с образование дендритов начинается при 400 °С и практически за-канчивается при 500-700 °С, и последующий крат-ковременный отжиг в течение 30 с при 850 °С не ока-зывает существенного влияния.…”

Section: результаты эксперимента и их обсуждениеunclassified

“…В результате отжига эти два нижних слоя металлизации (Ti/Al) обеспечивают низкое контактное сопротивление, взаимодействуя с полупроводником с образова-нием тонких слоев нитридов TiN и Al-Ti-N. Работа выхода этих образовавшихся слоев близка к работе выхода нитрида галлия. Эти слои при своем формировании создают много азотных вакансий в полупроводнике, действующих как доноры [1,2,9].…”

Section: Introductionunclassified

“…Наиболее популярна много-слойная система Ti/Al/Ni/Au, в других вариантах этой металлиза-ции никель заменен на тугоплав-кие металлы или соединения [1][2][3][4][5][6]9]. За нанесением многослойной металлизации следует формиро-вание нужного рисунка металли-зации с помощью технологии lift− off, и далее быстрый термический отжиг при высоких температурах 800-900 °С, во время которого формируются омические контакты к структурам AlGaN/GaN.…”

Section: Introductionunclassified

See 2 more Smart Citations

Research of Structure and Surface Morphology of Two–layer Contact Ti/Al Metallization

Ванюхин¹,

Zakharchenko²,

Каргин³

et al. 2015

Izv. vysš. učebn. zaved., Mater. èlektron. teh.

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Section: результаты эксперимента и их обсуждениеunclassified

Section: Introductionunclassified

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Research of Structure and Surface Morphology of Two–layer Contact Ti/Al Metallization

Ванюхин¹,

Zakharchenko²,

Каргин³

et al. 2015

Izv. vysš. učebn. zaved., Mater. èlektron. teh.

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“…The detailed HEMT mode l was used to refine the structure to resemble more c lose ly an actua l GaN HEMT, and was based on high effic iency power HEMTs by Fujitsu (2) and the work of Lee, Yeh, and H uang ( 8), as shown in figure 14. The dra in and source ohmic contacts for AlGaN/GaN HEMTs in th is m ode l are made from Titanium, Aluminum, Nicke l, and Gold (Ti/Al/Ni/Au) as seen by Yang (9). Secondly, buffer/passivatio n and nuc leation layers were include d in the mode l. The passivation layers placed above the AlGaN include a 200 nm doped GaN layer and a 200 nm Silic on N itride layer.…”

Section: Comsol® Multiphys Ics -Simple Hemtmentioning

confidence: 99%

(Invited) The Effect of Thermally Induced Piezoelectricity on GaN HEMT Device Characteristics

2015

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GaN is increasingly be ing used in a wide variety of power electronic applications. The piezoelectric nature of GaN, however, can result in defect generation and can modify the electrical performance of power devices, especially AlGaN/GaN high electron mobility transistors (HEMTs). The cooling mechanisms used to cool the GaN can create thermal gradients that can exaggerate this piezoelectric effect. In this study, multiphys ics finite element mode ling was used to determine the thermal gradients, the resulting thermo-mechanical stresses, and the attendant changes in the electric fields resulting from piezoelectric interaction seen in the HEMT. Devices were then tested on a probe station to va lidate the results of the mode ling. Evident dra in and gate current and on-resistance degradation were observed after a 30 minute voltage and current stress was applied to the HEMT.

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“…8,9 However, it results in increased R C due to low metal diffusion beneath the metal contact. 11,12 In this work, we propose a fabrication process of ohmic contacts to reduce R C of AlGaN/GaN HEMTs with a high Al concentration, while avoiding implantations that cause HF-traps and gate leakage. This is essential for enhancing device DC and RF performance.…”

mentioning

confidence: 99%

Low Source/Drain Contact Resistance for AlGaN/GaN HEMTs with High Al Concentration and Si-HP [111] Substrate

Duffy

Benbakhti

Mattalah

et al. 2017

ECS J. Solid State Sci. Technol.

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An optimized fabrication process of ohmic contacts is proposed to reduce the source/drain access resistance (R C ) and enhance DC/RF performance of AlGaN/GaN HEMTs with a high Al concentration. We show that source/drain R C can be considerably lowered by (i) optimally etching into the barrier layer using Ar + ion beam, and by (ii) forming recessed contact metallization using an optimized Ti/Al/Ni/Au (12 nm/200 nm/40 nm/100 nm) multilayers. We found that a low R C of ∼0.3 .mm can be achieved by etching closer to the 2-Dimensional Electron Gas (2DEG) at an optimum etching depth, 75% of the barrier thickness, followed by a rapid thermal annealing at 850 • C. This is due to the very small distance between the alloy and the 2DEG (higher electric field) as shown by 2D AlGaN/GaN High Electron Mobility Transistors (HEMTs) are significantly beneficial to the semiconductor device industry. They have the potential to replace Si in a range of high-power and high-frequency applications due to the wide bandgap, high electron saturation velocity, good thermal conductivity and high piezoelectricity of III-Nitrides materials.1-4 To fully benefit from the aforementioned material properties, reduction of extrinsic source and drain access resistances (R C ) of AlGaN/GaN HEMTs is essential to enhance their DC/RF performance. To achieve this, several methodologies have been previously proposed.5-9 Firstly, implanting Si into the AlGaN barrier is known to reduce ohmic contact, R C . However, annealing contacts at high temperatures, to activate dopants, results in diffusion of the Si dopants away from the contacts. The result is increased high-frequency (HF) charge trapping and gate leakage current.10 Secondly, increasing the Al concentration in the barrier and/or using AlN exclusion layer is known to increase 2-Dimensional Electron Gas (2DEG) confinement and to enhance 2DEG density and mobility, which enhances performance. 8,9 However, it results in increased R C due to low metal diffusion beneath the metal contact. 11,12 In this work, we propose a fabrication process of ohmic contacts to reduce R C of AlGaN/GaN HEMTs with a high Al concentration, while avoiding implantations that cause HF-traps and gate leakage. This is essential for enhancing device DC and RF performance. For this new proposal, the outer edges of an AlGaN/GaN HEMT, where the source and drain ohmic contacts are to be placed, are etched from the surface of the device down into the AlGaN barrier layer. Contact metal is then evaporated onto the etched locations and rapidly annealed under high temperatures. During the annealing process, contact metal diffuses into the AlGaN barrier layer to form an alloy beneath the metal contact. The change in R C at different etching depths at various annealing conditions is investigated to identify the optimal etching depth given by the lowest R C .The epi-structure of the investigated devices is presented in Device structure section of this paper. The source and drain contact metallization multilayer scheme and ohmic contact formatio...

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Analysis of the ohmic contacts of Ti/Al/Ni/Au to AlGaN/GaN HEMTs by the multi-step annealing process

Cited by 12 publications

References 9 publications

Research of Structure and Surface Morphology of Two–layer Contact Ti/Al Metallization

Research of Structure and Surface Morphology of Two–layer Contact Ti/Al Metallization

(Invited) The Effect of Thermally Induced Piezoelectricity on GaN HEMT Device Characteristics

Low Source/Drain Contact Resistance for AlGaN/GaN HEMTs with High Al Concentration and Si-HP [111] Substrate

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