Source/Drain Via Etch Profile Control to Prevent Leakage
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Solution Overview
Problem
The lateral etching during the liner removal (LRM) process in the formation of via openings leads to an increased risk of leakage current due to the bowing profile of the via openings, which can result in electrical leakage between the source/drain via and the gate contact.
Innovation Solution
An additional plasma treatment is applied to the MCESL sidewalls to create an oxidized region with different etch selectivity, slowing down lateral etching and reducing the risk of leakage current by inhibiting over-etching of the source/drain contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the LRM process is used to form via openings, then the via openings can be formed efficiently, but lateral etching causes bowing profile that increases leakage current risk
Solution Approach 1:
The patent applies plasma treatment selectively to the MCESL sidewalls to create an oxidized region with different etch selectivity. This local modification of material properties at the sidewall region inhibits lateral etching specifically where it causes bowing, while maintaining vertical etching progress through the via opening formation process.
Solution Approach 2:
The plasma treatment is applied before the LRM etching process to pre-oxidize the MCESL sidewalls. This preliminary action creates a protective oxidized layer that modifies the etch selectivity during subsequent LRM processing, preventing lateral etching and bowing profile formation before they can occur.
2Manufacturing precision
If lateral etching occurs during LRM process, then via openings can be formed, but over-etching of source/drain contacts occurs leading to electrical leakage
Solution Approach 1:
The oxidized region is created locally on the MCESL sidewalls through plasma treatment, creating a zone with modified etch selectivity. This local property change prevents lateral etching at the sidewall interface while allowing controlled vertical etching to proceed, maintaining precise via opening geometry without over-etching adjacent structures.
Solution Approach 2:
The oxidized region acts as an intermediary layer between the MCESL and the etchant during LRM processing. This intermediate oxidized layer modifies the interaction between the etchant and the MCESL sidewalls, reducing lateral etching rates and preventing direct over-etching of the source/drain contacts.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The plasma treatment on the MCESL sidewalls effectively reduces the risk of leakage current by controlling the etching process, ensuring precise via opening formation without excessive lateral expansion.
Implementation Method 1
An additional plasma treatment is applied to the MCESL sidewalls to create an oxidized region with different etch selectivity
Data Source
AI summary
A device comprises a source/drain contact over a source/drain region of a transistor, an etch stop layer above the source/drain contact, an interlayer dielectric (ILD) layer above the etch stop layer, and a source/drain via extending through the ILD layer and the etch stop layer to the source/drain contact. The etch stop layer has an oxidized region in contact with the source/drain via and separated from the source/drain contact.