Nanosheet Source/Drain Contact Layout to Prevent Gate Shorts
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Solution Overview
Problem
Semiconductor devices face challenges in preventing short circuits between source/drain contacts and gate electrodes, particularly due to the lack of effective etching techniques that ensure proper spacing and insulation in multi-gate transistors.
Innovation Solution
The semiconductor device employs a configuration where the source/drain contact penetrates an etching stop layer and interlayer insulating layer, with a silicide layer only on the bottom surface of the contact and no silicide on the sidewalls, and an etching stop layer and interlayer insulating layer are strategically placed between the source/drain contact and the nanosheets to prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If source/drain contact material is used to ensure good electrical connection, then electrical conductivity is improved, but short circuit between source/drain contact and gate electrode may occur
Solution Approach 1:
An etching stop layer is introduced as an intermediary between the source/drain contact and the gate electrode/nanosheets. This layer acts as a barrier that prevents direct contact and potential short circuits while allowing the contact to maintain its electrical connection function to the source/drain region.
Solution Approach 2:
The insulation structure is segmented into multiple layers: the etching stop layer positioned between the source/drain contact and the interlayer insulating layer, and the interlayer insulating layer positioned between the etching stop layer and the nanosheets. This segmentation creates multiple barriers against short circuits.
2Reliability
If etching stop layer and interlayer insulating layer are added to prevent short circuits, then short circuit prevention is improved, but device structure complexity increases
Solution Approach 1:
The etching stop layer serves multiple functions: it prevents short circuits between the source/drain contact and gate electrode, provides a planar surface for subsequent processing steps, and acts as a barrier to material diffusion. This multi-functionality reduces the need for additional separate structures.
3Reliability
If source/drain contact penetrates deep to connect with source/drain region, then electrical connection is improved, but risk of contacting gate electrode increases
Solution Approach 1:
The etching stop layer is formed beforehand before depositing the source/drain contact material. This preliminary action establishes a protective barrier in advance, allowing the contact to be etched deeply to reach the source/drain region without risking contact with the gate electrode or nanosheets.
Data Source
AI summary
A semiconductor device includes a substrate. An active pattern is on the substrate and extends in a first horizontal direction. First to third nanosheets are sequentially stacked on the active pattern and are spaced apart from each other in a vertical direction. A gate electrode is on the active pattern and extends in a second horizontal direction. The gate electrode surrounds each of the first to third nanosheets. A source/drain region is on the active pattern on at least one side of the gate electrode. An interlayer insulating layer covers the source/drain region. A source/drain contact penetrates the interlayer insulating layer in the vertical direction and is connected to the source/drain region. At least a portion of the interlayer insulating layer is disposed between sidewalls of the source/drain contact and the source/drain region in the first horizontal direction and overlaps sidewalls of the third nanosheet along the first horizontal direction.