For the Ge nanowire formation in a gate-all-around (GAA) integration scheme, a selective etch of Si0.5Ge0.5 or Si0.3Ge0.7 selective to Ge is considered. Two wet process approaches were evaluated: a boiling TMAH as a commodity chemistry is compared with a formulated chemistry using a multi-stack SiGe/Ge layer as a test vehicle. The boiling TMAH exhibits an anisotropic etch of the SiGe whereas the formulated semi-aqueous chemistry removes the sacrificial SiGe by an isotropic etch which makes the process suitable for a Ge nanowire release process.

A selective wet etching process for fabricating SiGe and Ge nanowires for gate all around transistors is introduced in this paper. Two formulated proprietary chemical mixtures with highly selective etching properties (Si vs. SiGe and SiGe vs. Ge) can effectively dissolve the sacrificial layers with minimal damage to the interstitial nanowire materials. The Auger Electron Spectroscopy (AES) surface characterization indicates that no chemical contamination is left after the wet etching process.

Gate All-Around (GAA) is considered a key design feature for future CMOS technology. SiGe vs. Si selective etch is required for Si nanowire formation in GAA. It is confirmed the selective SiGe removal with commodity chemical (mixtures of hydrofluoric acid (HF), hydrogen peroxide (H2O2) and acetic acid (CH3COOH, HAc)), however the thick oxidized layer on Si NW was observed after commodity chemical process, which is indicated the significant Si NW loss. On the other hand, the formulated mixture ACT® SG-101, which is focusing on SiGe oxidizer, chemical pH, solvent polarity & corrosion inhibitor for chemical concept, was performed higher selectivity and lower Si loss than commodity chemical. The formulated mixture has also been used to form an inner spacer for cavity etch scheme and confirmed uniform cavity etch and inner spacer filling on topological test structure.

Ultrapure water contains dilute hydrogen peroxide as an impurity. In order to clarify an impact of the dilute hydrogen peroxide on cleaning processes, a SiGe epitaxial layer was deposited on a Si(100) wafer which surface was treated by HF last process with hydrogen peroxide contained UPW or hydrogen peroxide removed UPW. The defect in the SiGe epitaxial layer was reduced when the hydrogen peroxide removed UPW was used.

of these new materials have necessitated the evaluation of new chemicals and processing methods. The control of the Dissolved Oxygen (DO) concentration to suppress Cu corrosion is well established in BEOL processing and likewise in order to achieve a hydrophobic surface after pre-epi cleaning in FEOL surface preparation [2].