Multi-Spacer Gate Structure Against Wet Etchant Penetration
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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 for enhanced protection, and a third spacer, which collectively 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 is introduced as an intermediary protective element between the wet chemical etchants and the gate dielectric layer. The spacers act as a physical barrier that mediates the interaction, allowing etching processes to proceed while preventing direct contact between etchants and the gate dielectric, thus resolving the contradiction between effective etching and device yield protection
Solution Approach 2:
The multi-spacer structure is formed prior to the wet chemical etching process, establishing protective barriers in advance. This preliminary action ensures that when etchants are applied, the gate dielectric layer is already shielded, preventing damage before it can occur and maintaining both manufacturing effectiveness and device reliability
2Device complexity
If single spacer structures are used, then device structure is simpler, but protection against etchant penetration is insufficient
Solution Approach 1:
The protective function is segmented into multiple discrete spacer structures rather than relying on a single spacer. This segmentation creates multiple barriers that collectively provide superior protection against etchant penetration, with each spacer contributing to the overall protective capability while maintaining manageable individual structures
Solution Approach 2:
The multi-spacer structure employs a nested arrangement where spacers are positioned in hierarchical layers, with inner spacers providing protection closer to the gate dielectric and outer spacers providing additional shielding. This nesting strategy creates a graduated defense system that effectively blocks etchant penetration while organizing complexity in a structured manner
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.