GAA Source/Drain Contact Isolation Structure With CESL Sidewall Removal
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Solution Overview
Problem
The challenge in advanced technology nodes is forming isolated contacts to semiconductor device features, particularly in gate all around (GAA) transistors, due to sidewall merging during deposition, which leads to voids in isolation structures.
Innovation Solution
The contact etch stop layer (CESL) is partially or fully removed from sidewalls before depositing isolation structure material, increasing spacing and reducing sidewall merging during deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the contact etch stop layer is removed from sidewalls before depositing isolation structure material, then sidewall merging is reduced and void formation is minimized, but the manufacturing process complexity increases
Solution Approach 1:
The contact etch stop layer is removed from sidewalls before depositing isolation structure material. This preliminary action prevents sidewall merging during deposition, ensuring proper isolation structure formation and eliminating voids that would compromise manufacturing precision.
Solution Approach 2:
The contact etch stop layer is selectively removed from sidewall regions while being retained in other areas. This extraction of the layer from specific locations enables precise control over isolation structure formation without affecting the entire device structure.
2Manufacturing precision
If the contact etch stop layer is partially or fully removed from sidewalls, then spacing between structures is increased and sidewall merging is reduced, but material is lost
Solution Approach 1:
The contact etch stop layer is selectively removed only from sidewall regions where isolation structures need to be formed, while being retained in other areas. This local quality approach increases spacing and prevents merging only where necessary, minimizing overall material loss.
Solution Approach 2:
The contact etch stop layer is partially removed from sidewalls rather than completely removed from the entire device. This partial action provides sufficient spacing control to prevent sidewall merging while conserving material by maintaining the layer in non-critical regions.
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
This method enhances yield by minimizing void formation in isolation structures, improving the manufacturing process of GAA transistors.
Implementation Method 1
The contact etch stop layer (CESL) is partially or fully removed from sidewalls before depositing isolation structure material
Implementation Method 2
before depositing isolation structure material
Data Source
AI summary
A device includes a substrate and a gate structure wrapping around at least one vertical stack of nanostructure channels. The device includes a source/drain region abutting the gate structure, and a source/drain contact over the source/drain region. The device includes an etch stop layer laterally between the source/drain contact and the gate structure and having a first sidewall in contact with the source/drain contact, and a second sidewall opposite the first sidewall. The device includes a source/drain contact isolation structure embedded in the source/drain contact and having a third sidewall substantially coplanar with the second sidewall of the etch stop layer.