Multi-Spacer Gate Structure for Etchant Protection
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Solution Overview
Problem
The semiconductor industry faces challenges in protecting gate dielectric layers during fabrication processes, as wet chemical etchants can damage these layers, leading to reduced device yield and potential device failure.
Innovation Solution
A multi-spacer structure is introduced, comprising a first spacer on the gate stack sidewall, a second spacer with a wedge-shaped lower portion, and a third spacer, which provides a protective seal to prevent wet etchants from reaching the gate dielectric layer, thereby reducing damage during etching and cleaning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet chemical etchants are used during fabrication processes, then etching and cleaning can be performed effectively, but gate dielectric layers can be damaged leading to reduced device yield
Solution Approach 1:
A multi-spacer structure comprising first, second, and third spacers is introduced as an intermediary protective barrier between the gate dielectric layer and the wet chemical etchants. The spacers are positioned around the gate stack to prevent direct contact between the etchants and the gate dielectric layer, thereby allowing effective etching and cleaning processes while protecting the gate dielectric layer from damage and maintaining device yield.
2Ease of operation
If gate dielectric layers are exposed during fabrication, then subsequent processing can be performed, but damage from etchants can occur
Solution Approach 1:
The protective structure is segmented into multiple spacers (first, second, and third spacers) positioned at different locations around the gate stack. This segmentation allows subsequent processing to be performed on exposed regions while the spacers strategically block etchants from reaching the gate dielectric layer, thus providing processing accessibility while preventing etchant damage.
3Reliability
If protective measures are added to gate structures, then gate dielectric layers are protected, but device complexity increases
Solution Approach 1:
The multi-spacer structure serves multiple functions simultaneously: it acts as a protective barrier against wet chemical etchants, provides a framework for subsequent processing steps, and maintains structural organization around the gate stack. By consolidating these functions into a single integrated structure, the increase in device complexity is minimized while achieving comprehensive gate dielectric protection.
Data Source
AI summary
The present disclosure relates to a semiconductor device including a substrate having a top surface and a gate stack. The gate stack includes a gate dielectric layer on the substrate and a gate electrode on the gate dielectric layer. The semiconductor device also includes a multi-spacer structure. The multi-spacer includes a first spacer formed on a sidewall of the gate stack, a second spacer, and a third spacer. The second spacer includes a first portion formed on a sidewall of the first spacer and a second portion formed on the top surface of the substrate. The second portion of the second spacer has a thickness in a first direction that gradually decreases. The third spacer is formed on the second portion of the second spacer and on the top surface of the substrate. The semiconductor device further includes a source/drain region formed in the substrate, and a portion of the third spacer abuts the source/drain region and the second portion of the second spacer.