CMOS compatible low-resistivity Al—Sc metal etch stop
| DWPI Title: Semiconductor device used in conjunction with overlying aluminum nitride or aluminum scandium nitride piezoelectric layer, has adhesion promoting layer on substrate, layer comprises aluminium-scandium adhesion promoting layer having crystallographic orientation due to adhesion promoting layer |
| Abstract: An aluminum-scandium (Al—Sc) etch stop that is both CMOS compatible and highly conductive, and a method for forming the same are disclosed. The low volatility of Sc in Cl and strong covalent bond between Al—Sc leads to an increase in resistance to NaCl corrosion and makes it difficult to dry etch in Cl-based chemistries, resulting in an excellent etch stop material, especially when used in conjunction with an overlying aluminum nitride (AlN) or aluminum scandium nitride (AlScN) piezoelectric layer. When deposited at high deposition temperatures or when subsequently annealed at >600° C., the Al—Sc has a low resistivity, enabling corresponding device operation at temperatures up to at least 500° C. While Al3Sc is the preferred composition, Al1-xScx with x between 5 and 100 atomic percent provides many of these same benefits but comes at the cost of increased electrical resistivity and etch resistance with increasing Sc content due to Sc oxidation. |
| Use: Semiconductor device used in conjunction with overlying aluminum nitride (AlN) or aluminum scandium nitride (AlScN) piezoelectric layer. |
| Advantage: The semiconductor device enables to achieve improvements in corrosion resistance to sodium chloride (NaCl) through a higher deposition temperature and/or a subsequent anneal. |
| Novelty: Semiconductor device (100) has a substrate (110), an adhesion promoting layer on the substrate, a layer comprises 80% aluminium-scandium (Al3Sc) on the adhesion promoting layer, which comprises 80% Al3Sc having a crystallographic orientation of 111, that is due to the adhesion promoting layer, and an active layer (130) on the layer comprises 80% Al3Sc. |
| Filed: 8/2/2021 |
| Application Number: US17391415A |
| Tech ID: SD 15233.1 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
| Data from Derwent World Patents Index, provided by Clarivate All rights reserved. Republication or redistribution of Clarivate content, including by framing or similar means, is prohibited without the prior written consent of Clarivate. Clarivate and its logo, as well as all other trademarks used herein are trademarks of their respective owners and used under license. |