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Multilayer ohmic contact system of gallium nitride device with composite metal barrier layer

A technology of ohmic contact and composite metal, applied in the direction of metal layered products, chemical instruments and methods, semiconductor/solid-state device manufacturing, etc., can solve the problems of low ohmic contact resistivity, device failure, reliability impact, etc., and achieve good surface The effects of flatness, small ohmic contact resistivity, and high reliability

Active Publication Date: 2012-10-10
NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The advantage of Ti / Al / Ti / Au, Ti / Al / Ni / Au, Ti / Al / Pt / Au as AlGaN / GaN HEMT ohmic contact metal system is that it can obtain lower ohmic contact resistivity, especially Ti / Al The ohmic contact resistivity formed by / Ni / Au can reach 0.2Ω·mm or even lower (Jacobs et al., J.Crys.Growth 241(15-18) 2002), but its disadvantage is that the surface roughness of the ohmic contact is relatively large , not smooth enough, which affects the photolithographic registration in the subsequent process on the one hand, and on the other hand, its reliability at high temperature will also be affected. The Au metal used will pass through the thinner ohmic contact metal layer The way of migration into the semiconductor, so as to form such as figure 1 Voids as shown (Mark J. Rosker, The DARPA Wide Band Gap Semiconductor for RF Applications (WBGS-RF) Program: Phase II Results, CSMANTECH 2009 presentation), leading to device failure
[0004] The advantage of Ti / Al / Mo / Au as AlGaN / GaN HEMT ohmic contact metal system is that it can obtain good surface flatness, which is mainly due to the high melting point of metal Mo (melting point 2623 ° C), and the mutual solubility of Au and Mo Low (the solubility of Au in Mo at 850 ° C is less than 1%), it will be able to prevent Au from entering the semiconductor through the Mo layer during the process of forming ohmic contacts and during high-temperature use of the device, thereby contributing to Improve the reliability of the device, but the disadvantage of Ti / Al / Mo / Au as AlGaN / GaN HEMT ohmic contact metal system is that its ohmic contact resistivity is larger than that of Ti / Al / Ni / Au

Method used

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  • Multilayer ohmic contact system of gallium nitride device with composite metal barrier layer
  • Multilayer ohmic contact system of gallium nitride device with composite metal barrier layer
  • Multilayer ohmic contact system of gallium nitride device with composite metal barrier layer

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Embodiment 1

[0021] Figure 3-Figure 6 Is the implementation steps of an embodiment of the present invention, first as image 3 As shown, a photoresist layer 14 is coated on the AlGaN barrier layer 13, and then exposed and developed to form a Figure 4 The graph shown, again as Figure 5 The shown metal layer 15 is placed on the AlGaN barrier layer 13 and the photoresist layer 14, and finally the photoresist 14 and the metal layer 15 thereon are removed through stripping to obtain the following Figure 6 Source electrode 16 and drain electrode 17 are shown.

[0022] Wherein the metal layer 15 such as Figure 11 It is composed of five metal layers, starting from the interface of AlGaN layer 13 and metal layer 15 , consisting of Ti metal layer 20 , Al metal layer 21 , Ni metal layer 22 , Mo metal layer 23 and Au metal layer 24 . The thickness of the Ti metal layer 20 is 15nm-30nm, the ratio of the Al metal layer 21 to the Ti metal layer is 3-10, the thickness of the Ni metal layer 22 is ...

Embodiment 2

[0027] control Figure 10 , first as image 3 As shown, a photoresist layer 14 is coated on the AlGaN barrier layer 13, and then exposed and developed to form a Figure 4 The graph shown, again as Figure 10 The metal layer 19 is deposited on the AlGaN barrier layer 13 and the photoresist layer 14 as shown, and finally the photoresist 14 and the metal layer 19 on it are removed through stripping to obtain the following Figure 6 Source electrode 16 and drain electrode 17 are shown.

[0028] Wherein the metal layer 19 such as Figure 12 As shown, it consists of six metal layers, starting from the interface between the AlGaN layer 13 and the metal layer 19, successively consisting of a Ti metal layer 25, an Al metal layer 26, a Ni metal layer 27, a Mo metal layer 28, a Ti metal layer 29 and an Au metal layer. Layer 30 composition. The thickness of the Ti metal layer 25 is 15nm-30nm, the ratio of the Al metal layer 26 to the Ti metal layer is 3-10, the thickness of the Ni me...

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Abstract

The invention discloses a multilayer ohmic contact system of a gallium nitride device with a composite metal barrier layer, which is characterized in that the ohmic contact system adopted by a source electrode 16 and a drain electrode 17 of an aluminum-gallium-nitrogen (AlGaN) / gallium nitride (GaN) high electron mobility transistor (HEMT) is Ti / Al / Ni / Mo / Au. The ohmic contact system has the advantage of simultaneously meeting the requirements on low ohmic contact resistivity, high surface evenness and high reliability required by the AlGaN / GaN HEMT. In the embodiment 1, good ohmic contact withan AlGaN layer 13 can only be formed after high-temperature thermal annealing under the protection of inert gas such as N2; and in the embodiment 2, the problem of poor adhesion between an Mo metal layer 28 and an Au metal layer 30 can be solved through a Ti metal layer 29, so that the requirement that the metal Au on the uppermost layer of ohmic contact is thick on some occasions is met.

Description

Technical field: [0001] The invention relates to a multilayer ohmic contact system of a gallium nitride device with a composite metal barrier layer, which is an ohmic contact system with a composite metal barrier layer suitable for aluminum gallium nitride compound / gallium nitride high electron mobility transistors. It belongs to the field of semiconductor technology. Background technique: [0002] At present, aluminum gallium nitride (AlGaN) / gallium nitride (GaN) high electron mobility transistor (HEMT) generally adopts Ti / Al-based multilayer metal ohmic contact system, such as Ti / Al / Ti / Au, Ti / Al / Ni / Au, Ti / Al / Pt / Au, Ti / Al / Mo / Au, etc., using evaporation or sputtering to sequentially deposit Ti, Al, Ti (Ni or Pt or Mo, etc.), Au on the surface of the AlGaN layer , and annealed at a high temperature of about 800°C to form an ohmic contact. The principle is generally believed to be that Ti reacts with Al to form Al at a lower temperature (200-300°C). 3 Ti, when the temperatu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L21/3205B32B15/01
Inventor 任春江陈堂胜
Owner NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD