Metal microelectromechanical systems (MEMS) provide attractive properties such as high reflectivity and high conductivity. They are typically processed using an organic sacrificial layer that is removed by an oxygen ash. This enables low-temperature processing but presents other problems. For example, ashing is not applicable to metals that are susceptible to oxidation. However, if an inorganic sacrificial silicon dioxide is used, its removal commonly involves acids, exposure to which can be detrimental to metals. For example, metallic films are susceptible to hydrogen incorporation, resulting in large compressive stress. In recent work with structural tantalum and sacrificial silicon dioxide as a model system, we demonstrated that hydrogen injected during the release process can induce 1200 MPa compressive stress. This work explores AlN and Cu as alternative sacrificial materials in which release etching of structural Ta by AZ 400K developer and FeCl3 solution, respectively, is hydrogen free. Isotropic release etching is observed for Cu at room temperature and for AlN above 60 °C. In comparison with 1200 MPa, the uniaxial stress change after structure release is 80 MPa compressive with Cu and is unchanged after AlN sacrificial etch. [2021-0005]

中文翻译：

---

用于金属 MEMS 的牺牲材料和释放蚀刻剂，可减少或消除氢引起的残余应力变化


金属微机电系统 (MEMS) 具有高反射率和高导电率等极具吸引力的特性。它们通常使用有机牺牲层进行处理，并通过氧灰去除。这使得低温处理成为可能，但也带来了其他问题。例如，灰化不适用于易氧化的金属。然而，如果使用无机牺牲二氧化硅，其去除通常涉及酸，接触酸可能对金属有害。例如，金属薄膜容易掺入氢，从而产生较大的压应力。在最近以结构钽和牺牲二氧化硅作为模型系统的研究中，我们证明了在释放过程中注入的氢气可以引起 1200 MPa 的压应力。这项工作探索了 AlN 和 Cu 作为替代牺牲材料，其中 AZ 400K 显影剂和 FeCl3 溶液分别释放结构 Ta 的蚀刻是无氢的。 Cu 在室温下观察到各向同性释放蚀刻，而 AlN 在 60 °C 以上观察到各向同性释放蚀刻。与 1200 MPa 相比，结构释放后的单轴应力变化为 Cu 压缩后的 80 MPa，并且在 AlN 牺牲蚀刻后没有变化。 [2021-0005]