US 11,855,192 B2
Semiconductor device and manufacturing method thereof
Han-Yu Lin, Nantou County (TW); Fang-Wei Lee, Hsinchu (TW); Kai-Tak Lam, Hsinchu (TW); Raghunath Putikam, Hsinchu (TW); Tzer-Min Shen, Hsinchu (TW); Li-Te Lin, Hsinchu (TW); Pinyen Lin, Rochester, NY (US); Cheng-Tzu Yang, Hsinchu County (TW); Tzu-Li Lee, Yunlin County (TW); and Tze-Chung Lin, Hsinchu (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD., Hsinchu (TW); and TSMC NANJING COMPANY LIMITED, Nanjing (CN)
Filed by TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD., Hsinchu (TW); and TSMC Nanjing Company Limited, Nanjing (CN)
Filed on Jan. 19, 2021, as Appl. No. 17/152,432.
Claims priority of application No. 202011392694.X (CN), filed on Dec. 2, 2020.
Prior Publication US 2022/0173224 A1, Jun. 2, 2022
Int. Cl. H01L 29/66 (2006.01); H01L 21/8234 (2006.01); H01L 29/78 (2006.01)
CPC H01L 29/6681 (2013.01) [H01L 21/823431 (2013.01); H01L 29/785 (2013.01); H01L 2029/7858 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method comprising:
forming a fin structure comprising a plurality of first semiconductor layers and a plurality of second semiconductor layers alternately stacked over a substrate;
forming a dummy gate structure across the fin structure such that the dummy gate structure covers a first portion of the fin structure while second portions of the fin structure are exposed;
removing the exposed second portions of the fin structure;
after removing the exposed second portions of the fin structure, performing a first oxygen-removal process, using hydrogen radicals, to remove oxv ens in the first semiconductor layers;
after removing the exposed second portions of the fin structure, performing a second oxygen-removal process, using a hydrogen-containing gas mixture, to remove a native oxide layer formed on sidewalls of the first semiconductor layers, wherein the hydrogen radicals used in the first oxygen-removal process has sizes smaller than the hydrogen-containing gas mixture used in the second oxygen-removal process;
after performing the first oxygen-removal process, performing a selective etching process, using an etching gas mixture comprising a hydrogen-containing gas and an F2 gas, to laterally recess the first semiconductor layers in the first portion of the fin structure, wherein the selective etching process etches the first semiconductor layers at a faster etching rate than etching the second semiconductor layers;
forming inner spacers on opposite end surfaces of the laterally recessed first semiconductor layers of the first portion of the fin structure;
forming source/drain epitaxial structures on opposite end surfaces of the second semiconductor layers in the first portion of the fin structure;
removing the dummy gate structure to expose the first portion of the fin structure;
removing the laterally recessed first semiconductor layers in the exposed first portion of the fin structure while leaving the second semiconductor layers in the exposed first portion of the fin structure suspended above the substrate; and
forming a gate structure to surround each of the suspended second semiconductor layers.