US 12,087,616 B2
Air gap formation method
Chun-Chih Ho, Taichung (TW); Yu-Chung Su, Hsinchu (TW); Ching-Yu Chang, Yilang County (TW); and Chin-Hsiang Lin, Hsinchu (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD., Hsinchu (TW)
Filed by TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD., Hsinchu (TW)
Filed on Apr. 14, 2022, as Appl. No. 17/720,789.
Claims priority of provisional application 63/303,642, filed on Jan. 27, 2022.
Prior Publication US 2023/0238275 A1, Jul. 27, 2023
Int. Cl. H01L 21/762 (2006.01); H01L 21/768 (2006.01)
CPC H01L 21/76289 (2013.01) [H01L 21/76813 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of forming a semiconductor device, comprising:
forming a plurality of non-insulator structures on a substrate, the plurality of non-insulator structures being spaced apart by trenches;
forming a sacrificial layer overfilling the trenches;
reflowing the sacrificial layer at an elevated temperature, wherein a top surface of the sacrificial layer after the reflowing is lower than a top surface of the sacrificial layer before the reflowing, and a middle of a first segment of the top surface of the sacrificial layer between two of the plurality of non-insulator structures after the reflowing is at a same elevation as a second segment of the top surface of the sacrificial layer directly over one of the plurality of non-insulator structures after the reflowing;
etching back the sacrificial layer to lower the top surface of the sacrificial layer to fall below top surfaces of the plurality of non-insulator structures;
forming a dielectric layer on the sacrificial layer; and
removing the sacrificial layer to form air gaps below the dielectric layer.