Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
Nanotechnology. 2010 Dec 17;21(50):505703. doi: 10.1088/0957-4484/21/50/505703. Epub 2010 Nov 22.
Gallium implantation of ZnO by a focused-ion beam is used to create a mask for ZnO dry etching with hydrogen. Effects of Ga(+) fluence on the etch stop properties and the associated mechanisms are investigated. The fluence of 2.8 × 10(16) cm(-2) is determined to be optimum to render the best mask quality. While lower fluences would cause less etching selectivity, higher fluences would cause erosion of the surface and particles to be precipitated on the surface after H(2) treatment at high temperature. In contrast to the commonly adopted gallium oxide formation on Si, transmission electron microscopy analysis reveals that, for the fluences ≤ 2.8 × 10(16) cm(-2), Ga(+) ions are incorporated as dopants into ZnO without any second phases or precipitates, indicating the Ga-doped ZnO layer behaves as a mask for H(2) etching due to the higher electronegativity of Ga(+) towards oxygen. However, for the fluences ≥ 4.6 × 10(16) cm(-2), the surface particles are responsible for the etch stop and are identified as ZnGa(2)O(4). We finally demonstrate a complicated pattern of 'NCKU' on ZnO by using this technique. The study not only helps clarify the related mechanisms, but also suggests a feasible extension of the etch stop process that can be applied to more functional material.
采用聚焦离子束将镓植入氧化锌中，以创建用于氧化锌干法刻蚀的掩模。研究了 Ga(+)注入剂量对蚀刻停止性能的影响及其相关机制。确定 2.8×10(16)cm(-2)的注入剂量为最佳值，可获得最佳的掩模质量。较低的注入剂量会导致蚀刻选择性降低，而较高的注入剂量会导致表面侵蚀和颗粒在高温下用 H(2)处理后沉淀在表面上。与通常在 Si 上形成氧化镓不同，透射电子显微镜分析表明，对于注入剂量≤2.8×10(16)cm(-2)，Ga(+)离子作为掺杂剂掺入 ZnO 中，没有任何第二相或沉淀物，表明 Ga 掺杂 ZnO 层由于 Ga(+)对氧的电负性更高，因此可作为 H(2)蚀刻的掩模。然而，对于注入剂量≥4.6×10(16)cm(-2)，表面颗粒是蚀刻停止的原因，被鉴定为 ZnGa(2)O(4)。我们最终通过这项技术在 ZnO 上展示了一个复杂的“NCKU”图案。该研究不仅有助于澄清相关机制，还为可应用于更多功能材料的蚀刻停止工艺提供了可行的扩展。
