	US 11,908,731 B2
	Via-first self-aligned interconnect formation process
Yu-Tse Lai, Zhubei (TW); and Ya Hui Chang, Hsinchu (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Co., Ltd., Hsinchu (TW)
Filed on Jul. 9, 2021, as Appl. No. 17/371,556.
Claims priority of provisional application 63/188,205, filed on May 13, 2021.
Prior Publication US 2022/0367252 A1, Nov. 17, 2022
Int. Cl. H01L 21/768 (2006.01); H01L 23/522 (2006.01)

CPC H01L 21/76816 (2013.01) [H01L 21/76897 (2013.01); H01L 23/5226 (2013.01)]

20 Claims

1. A method comprising:

forming a dielectric layer over a substrate;

forming a first hard mask over the dielectric layer;

forming a second hard mask over the first hard mask;

etching the second hard mask to form a first opening in the second hard mask, wherein the first opening has a first width;

forming a third hard mask over the second hard mask and filling the first opening;

etching the third hard mask and the first hard mask to form a trench in the third hard mask and a second opening in the first hard mask, wherein the trench comprises a portion directly above the first opening, wherein the first opening is directly above the second opening, and wherein the trench has a second width that is less than the first width of the first opening, and the second opening has a third width that is smaller than or equal to the second width of the trench;

performing a first etching process on the dielectric layer to extend the trench and the second opening into the dielectric layer; and

forming a metal line and a via in the trench and the second opening, respectively.

11. A method comprising:

etching a dielectric layer to form:

a trench, wherein the dielectric layer comprises a first edge and a second edge facing the trench and parallel to a lengthwise direction of the trench; and

a via opening underlying and connected to the trench, wherein the dielectric layer further comprises:

a third edge and a fourth edge facing the via opening, wherein the third edge and the fourth edge are vertically aligned to the first edge and the second edge, respectively; and

a first curved edge connecting the third edge to the fourth edge; and

filling the trench and the via opening to form a metal line and a via, respectively.

19. A method comprising:

forming a first metal line comprising a first straight edge parallel to a lengthwise direction of the first metal line; and

forming a first via overlapped by the first metal line, wherein an entirety of the first via is directly underlying the first metal line, and the first via comprises:

a first curved edge overlapped by the first metal line; and

a second straight edge vertically aligned to the first straight edge of the first metal line, wherein the second straight edge is joined to the first curved edge.