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Top spacer erosion reduction based on cleans and RIE.

IP.com Disclosure Number: IPCOM000253191D
Publication Date: 2018-Mar-13
Document File: 3 page(s) / 261K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to reduce the cleans and reactive ion etch (RIE)-caused erosion from the spacer top without changing the spacer structure. The core idea is to implant impurities on the top of the spacers to improve the quality of the spacer and mitigate erosion from cleans and RIE.

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Title Top spacer erosion reduction based on cleans and RIE Abstract Disclosed is a method to help reduce the cleans and reactive ion etch (RIE)-caused erosion from the spacer top without changing the spacer structure. The core idea is to implant impurities on the top of the spacers to improve the quality of the spacer and mitigate erosion from cleans and RIE. Problem At the replacement metal gate (RMG), many cleans occur to prep the gate oxide. These cleans improve the quality of the high k deposited, with few traps and defects; however, the cleans come with a cost and attack other exposed materials. Some of these cleans, such as self-aligned contact (SAC) removal (HF) and top off removal (HF + COR) can cause the spacer top to erode. Apart from cleans, some RIE also impacts the erosion of spacers such as thick topside (TT) stack RIE, which mitigates the trench silicide-gate (TS-PC) shorts issue. Existing mechanisms (e.g., tri layer spacer) can help mitigate the erosion; however, current mechanisms degrade the low k of the spacer. Spacer top erosion has caused many issues inline and end-of-line (EOL). Some of the issues include:

• Modulation of chamfer depth • Shallow chamfer depth mitigates TS-PC issue • Deep chamfer depth causes PC open and Vt instability • Non-uniformity of weak ferromagnetic (WFM) shape • New process trilayer has helped this issue, but degrades the k

Figure 1: Illustration of the problem

A method is needed to reduce erosion from the spacer top as it is caused by cleans and RIE.

Solution/Novel Contribution The...