Fabrication and Characterization of Ohmic Contacts formed by Multi-layer Metal Stack on InGaAs

• Main Authors: Hsu, Chih-Lin, 許智晽
• Other Authors: Wu, Yew-chung
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/8kvbwv

碩士 === 國立交通大學 === 材料科學與工程學系所 === 107 === As the scale of device shrinking, the manufacturing technology of Si-based CMOS approaches its physical limit, which makes the devices encounter more non-ideal effects. Recently, searching alternative materials is the major research in semiconductor field. Among these novel materials, III-V compounds such as InGaAs, are considered to be one of the most promising candidate for n-channel materials due to its high electron mobility. In general, Ti/Pt/Au metal stack for ohmic contacts is fairly common. However, Au is quiet expensive. In this work, we introduced an Au-free ohmic contacts metal stack, which been developed in order to reduce the cost. Most research about III-V devices has focused on the electrical properties of the junctions, and thus, the reaction phases of metal and InGaAs remain unclear. Therefore, we focused on the identification of the reaction phase, and analyzed the relationship between reaction mechanisms and electrical properties. In this work, the reaction mechanisms and electrical properties of metal films contacts on n-InGaAs were characterized. Ti/Al and Ni/Al were used to be deposited on InGaAs. The metal-InGaAs alloys formed by rapid thermal annealing process (300oC~600oC/1min) have been characterized using TEM/EDS, XRD and AFM. The specific contact resistance of the contacts of metal films on n-InGaAs were extracted by circular transmission line model(CTLM). The results indicate, the contacts of Al/Ni/InGaAs and Al/Ti/InGaAs stack stayed stable after the samples subjected to 400oC annealing. In addition, the specific resistance of as-deposited Al/Ni/InGaAs and Al/Ti/InGaAs sample could attain 1.11x10-5 Ω·cm2 and 5.11x10-5 Ω·cm2, respectively. For Al/Ni/InGaAs, after annealing over 400oC, AlNi phase formed at the interface, which makes the specific resistance and the roughness increased dramatically. On the other hand, for Al/Ti/InGaAs, elements started to diffuse after 400oC annealing, and formed Al3Ti phase over 500oC. The formation of Al3Ti lead to the increasing of the specific resistance and the roughness as well. These results showed that in order to develop the Al/Ti/InGaAs and Al/Ni/InGaAs stack on InGaAs with low parasitic resistance, the processing temperature should be lower than 400oC.