We present an access technology suitable for scaled gallium nitride (GaN) high electron mobility transistor (HEMT) in Ka-band. The comparison between OFF-state characteristics of a silicon implant-assisted contact and a conventional recessed Ti/Al-based Ohmic contact is presented. The transistor with source/drain extension by Si implantation has a low contact resistance with ${R}_{C}$ down to $0.4 ~\Omega \cdot {\mathrm {mm}}$ and a sheet resistance of the implanted layer of $67~ \Omega $ /sq. In addition to promising contact performance, transistors with source and drain extension sustain high breakdown voltage (BV) with short dimensions for high-frequency applications. The systematic study of gate–source, gate–drain, and gate length variations shows a new breakdown mechanism for implanted access technology with current flowing beneath the channel leading to an unusual correlation between source–drain spacing and BV. With a conventional titanium-alloyed contact, a punchthrough effect is responsible for the BV. Cross-sectional transmission electron microscopy and secondary ion mass spectroscopy (SIMS) characterizations on both wafers highlight a degradation of the AlGaN-based back-barrier and a high silicon concentration deep into the epitaxial stack on the implanted wafers indicating a way to improve BV with an adapted process flow.

中文翻译：

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具有硅注入辅助接触的 200 mm 硅衬底上的 AlGaN/GaN HEMT 击穿机制


我们提出了一种适用于 Ka 波段缩放氮化镓 (GaN) 高电子迁移率晶体管 (HEMT) 的接入技术。比较了硅注入辅助接触和传统凹进式钛/铝基欧姆接触的断态特性。通过Si注入源/漏延伸的晶体管具有低接触电阻${R}_{C}$下降到$0.4 ~\Omega \cdot {\mathrm {mm}}$以及注入层的薄层电阻$67~\欧米茄$ /平方。除了具有良好的接触性能外，具有源极和漏极扩展的晶体管还能以短尺寸维持高击穿电压 (BV)，适合高频应用。对栅极-源极、栅极-漏极和栅极长度变化的系统研究表明，注入存取技术存在一种新的击穿机制，电流在沟道下方流动，导致源极-漏极间距和 BV 之间存在异常相关性。对于传统的钛合金触点，BV 是由穿通效应造成的。两个晶圆上的横截面透射电子显微镜和二次离子质谱 (SIMS) 表征都突出显示了基于 AlGaN 的背势垒的退化以及注入晶圆上外延堆叠深处的高硅浓度，这表明了一种提高 BV 的方法适应的工艺流程。