We present a novel test structure for the study of sidewall ohmic contacts to III–V fins for FinFETs. We apply it to the characterization of the impact of digital etch (DE), used to trim the fin width, and thermal annealing on the contact resistivity of Mo/ $\text{n}^{+}$ -InGaAs fin sidewall contacts. To obtain sidewall contacts, we leave in place the etch mask that is used to define the fins in a reactive ion etching process and deposit conformal Mo around them. We present a model that describes well the electrical characteristics of the test structure. In our results, we find that the specific acid that is used for DE or the number of DE cycles that are performed have a minor impact on contact resistivity. Thermal annealing is found to significantly improve the sidewall contact resistivity, with the best value of $3.7~ \pm ~0.2~ {\Omega } \cdot {\mu } \text{m}^{{2}}$ obtained after annealing at 400 °C. This is about three times higher than the reported contact resistivity for this contact technology with the contact wrapping around the top and the sidewall surfaces of fins, about $1.3~ {\Omega } \cdot {\mu }\text{m}^{{2}}$ . Also, we find that the width of the non-conductive region under the sidewall surface of Mo contact, which we term “deadzone,” can be significantly mitigated by thermal annealing. Our work highlights the importance of understanding sidewall ohmic contact formation for future high-performance InGaAs FinFETs.

中文翻译：

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对 InGaAs 鳍片的 Mo 侧壁欧姆接触的分析

我们提出了一种新的测试结构，用于研究 FinFET 的 III-V 鳍片的侧壁欧姆接触。我们将其应用于数字蚀刻 (DE) 影响的表征，用于修整鳍片宽度和热退火对 Mo/ $\text{n}^{+}$ -InGaAs 鳍片侧壁接触。为了获得侧壁接触，我们将用于在反应离子蚀刻工艺中定义鳍片的蚀刻掩模留在原位，并在它们周围沉积共形钼。我们提出了一个模型，可以很好地描述测试结构的电气特性。在我们的结果中，我们发现用于 DE 的特定酸或执行的 DE 循环次数对接触电阻率的影响很小。发现热退火可显着提高侧壁接触电阻率，最佳值为 $3.7~ \pm ~0.2~ {\Omega } \cdot {\mu } \text{m}^{{2}}$ 400℃退火后获得。这大约是该接触技术报告的接触电阻率的三倍，其中接触缠绕在鳍的顶部和侧壁表面，大约 $1.3~ {\Omega } \cdot {\mu }\text{m}^{{2}}$ . 此外，我们发现 Mo 触点侧壁表面下方的非导电区域的宽度，我们称之为“死区”，可以通过热退火显着减轻。我们的工作强调了理解侧壁欧姆接触形成对未来高性能 InGaAs FinFET 的重要性。