An increasing number of devices require high-aspect-ratio etching to increase the effective surface area while maintaining a small 2D footprint—3D memory architectures are a prime example. In the case of 3D FeRAM or FeFET devices, it is often necessary to etch these deep structures directly into metals such as W or TiN; however, such etch processes are typically constrained by poor mask selectivity, low etch rates at small critical dimensions (CD), and distorted profiles. Cryogenic etch offers the potential for innovative improvements in these areas—as it was demonstrated for silicon and dielectrics like SiO2/SiN—and investigating new, low-GWP (global warming potential) chemistries (e.g., Cl2, BCl3, F2) that have rarely been explored for cryoetch presents a compelling scientific opportunity