Germanium surface wet-etch-reconditioning for porous lift-off and substrate reuse

• DOI: 10.1016/j.mssp.2023.107851
• Publication Date: 2023-09-21T16:57:36Z
• Authors: Alexandre Chapotot; Bouraoui Ilahi; Javier Arias-Zapata; Tadeáš Hanuš; Ahmed Ayari; Gwenaëlle Hamon; Jinyoun Cho; Kristof Dessein; Maxime Darnon; Abderraouf Boucherif
• Keywords: Chemical Mechanical Planarization; Isotropic etching

International audience ; Reducing both the cost and weight of Germanium (Ge)-based devices is a key concern in extending these technologies to mainstream applications. In this framework, the porous Ge liftoff, based on a mesoporous Ge layer (PGe), shaped by bipolar electrochemical etching (BEE), constitutes an appealing strategy allowing the separation of lightweight, flexible, and low-cost devices and substrate reuse. However, after the device detachment, the broken pillar residues on the host substrate's surface prevent its reuse. Here, we report on the development and application of a reconditioning process based on an aqueous HF:H 2 O 2 :H 2 O (10:80:10, v-v-v) mixture without the need for Chemical Mechanical Polishing (CMP). We found that a mixed kinetic-and diffusion-controlled wet etching leads to surface polishing. Flat reconditioned substrates with