ZrON/GeON 双钝化层改善Ge MOS器件的界面特性和电特性

本文研究了利用等离子体氮化形成ZrON/GeON双钝化层制备Ge MOS器件的界面特性和电特性。结果发现，相比于N2等离子处理，NH3等离子处理制备的双钝化层显著改善了器件的界面和电特性，获得了低的界面态密度 (Dit = 1.64×1011 cm-2 eV-1)和栅极漏电流(Jg = 9.32×10-5 A cm-2@Vfb +1 V)，小的电容等效厚度 (CET = 1.11 nm)以及高的k值 (32). XPS分析表明，由NH3等离子体分解出的H原子和NH基团可以有效促进Ge表面不稳定低k GeOx的挥发，从而形成了高质量的GeON钝化层；且NH3等离子体氮化导致更多氮在ZrON/GeON中结合，能更有效阻止O、Ti、Ge等元素间的相互扩散，从而获得好的界面质量和电特性。

Improved interfacial and electrical properties of Ge MOS devices with ZrON/GeON dual passivation layer

The interfacial and electrical characteristics of Ge metal-oxide-semiconductor (MOS) devices with a dual passivation layer of ZrON/GeON formed by NH₃- or N₂-plasma treatment are investigated. The experimental results show that the NH₃-plasma treated sample exhibits significantly improved interfacial and electrical properties as compared to the samples with N₂-plasma treatment and no treatment: a lower interface-state density at the midgap (1.64 × 10¹¹ cm^-2·eV^-1) and gate leakage current (9.32 × 10^-5 A/cm² at V_fb+ 1 V), a small capacitance equivalent thickness (1.11 nm) and a high k value (32). X-ray photoelectron spectroscopy is used to analyze the involved mechanisms. It is indicated that more GeON and less GeO_x (x < 2) are formed on the Ge surface during NH₃-plasma treatment than the N₂-plasma treatment, resulting in a high-quality high-k/Ge interface, because H atoms and NH radicals in NH₃-plasma can enhance volatilization of the unstable low-k GeO_x, creating high-quality GeON passivation layer. Moreover, more nitrogen incorporation in ZrON/GeON induced by NH₃-plasma treatment can build a stronger N barrier and thus more effectively inhibit in-diffusion of O and Ti from high-k gate dielectric and out-diffusion of Ge.