	US 11,929,281 B2
	Reducing oxidation by etching sacrificial and protection layer separately
Chia Cheng Chou, Keelung (TW); Chung-Chi Ko, Nantou (TW); and Tze-Liang Lee, Hsinchu (TW)
Assigned to Taiwan Semiconductor Manufacturing Co., Ltd., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Co., Ltd., Hsinchu (TW)
Filed on Sep. 21, 2021, as Appl. No. 17/480,201.
Claims priority of provisional application 63/211,772, filed on Jun. 17, 2021.
Prior Publication US 2022/0406647 A1, Dec. 22, 2022
Int. Cl. H01L 21/768 (2006.01); H01L 23/532 (2006.01); H01L 23/535 (2006.01)

CPC H01L 21/7682 (2013.01) [H01L 21/76805 (2013.01); H01L 21/76846 (2013.01); H01L 21/76849 (2013.01); H01L 21/76895 (2013.01); H01L 23/5329 (2013.01); H01L 23/535 (2013.01)]

20 Claims

1. A method comprising:

etching a dielectric layer to form an opening, wherein a first conductive feature underlying the dielectric layer is exposed to the opening;

depositing a sacrificial spacer layer extending into the opening;

performing a first etching process to etch the sacrificial spacer layer, wherein a first bottom portion of the sacrificial spacer layer at a bottom of the opening is removed to reveal the first conductive feature, and a first vertical portion of the sacrificial spacer layer in the opening and on a sidewall of the dielectric layer is left to form a sacrificial ring;

depositing a protection layer extending into the opening and on the sacrificial ring;

performing a second etching process to etch the protection layer, wherein a second bottom portion of the protection layer is removed to reveal the first conductive feature, and a second vertical portion of the protection layer in the opening is left to form a protection ring;

forming a second conductive feature in the opening, wherein the second conductive feature is encircled by the sacrificial ring, and is over and electrically coupled to the first conductive feature; and

removing the sacrificial ring to form an air spacer.

13. A method comprising:

forming a first etch stop layer over a first conductive feature;

forming a dielectric layer over the first etch stop layer;

forming a structure comprising:

a second conductive feature in the dielectric layer and the first etch stop layer, wherein the second conductive feature is over and electrically coupling to the first conductive feature;

a protection ring encircling the second conductive feature; and

a sacrificial ring encircling the protection ring; and

removing the sacrificial ring to form an air spacer encircling the protection ring, wherein sidewalls of the dielectric layer are exposed to the air spacer.

18. A method comprising:

forming a first dielectric layer;

forming a first conductive feature in the first dielectric layer;

forming a second conductive feature over and electrically coupling to the first conductive feature, wherein the second conductive feature comprises:

a diffusion barrier; and

a metallic material encircled by the diffusion barrier;

forming a protection ring encircling and contacting the second conductive feature, wherein the protection ring contacts a top surface of at least one of the first dielectric layer and the first conductive feature; and

forming an air spacer encircling the protection ring, wherein the air spacer separates the protection ring from a second dielectric layer that encircles the air spacer.