Silicide-Blocking Layer for Leakage Control in Semiconductor Devices
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Solution Overview
Problem
In semiconductor IC device fabrication, the silicide layer can extend beyond the field oxide layer during spacer etching, leading to leakage current paths and device degradation due to exposure of source/drain regions.
Innovation Solution
A silicide-blocking layer, made of silicon oxide or silicon nitride, is formed over the border between the field oxide layer and source/drain regions to prevent the extension of the silicide layer, ensuring the edges of the source/drain regions remain higher than the field oxide layer and blocking the formation of silicide on exposed edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a blanket etching process is used to form spacers, then the field oxide layer edges are damaged and source/drain regions are exposed, but this leads to silicide layer extension onto source/drain regions causing leakage current
Solution Approach 1:
A silicide-blocking layer is introduced as an intermediary between the field oxide layer and the source/drain regions. This blocking layer prevents the silicide layer from extending onto the source/drain regions during the annealing process, thereby eliminating the leakage current path while allowing the blanket etching process to proceed for spacer formation.
Solution Approach 2:
The silicide-blocking layer is formed in advance before the metal layer deposition and annealing steps. This preliminary action ensures that even if the field oxide layer edges are damaged during spacer formation, the source/drain regions remain protected from silicide extension, preventing leakage current before it can occur.
2Manufacturing precision
If the field oxide layer edges are lowered due to damage, then source/drain regions become exposed, but this causes unwanted silicide formation and leakage current paths
Solution Approach 1:
The silicide-blocking layer serves as a protective intermediary that covers the exposed source/drain region edges. Even when the field oxide layer edges are lowered and source/drain regions are exposed, the blocking layer prevents direct contact between the metal layer and silicon, thereby preventing silicide formation and eliminating the leakage current harmful effect.
3Reliability
If silicide layer is formed on exposed source/drain regions, then contact resistance is reduced, but leakage current paths are created degrading device performance
Solution Approach 1:
The silicide-blocking layer is selectively positioned only at the critical locations where source/drain regions are exposed at the field oxide layer edges. This local application allows silicide formation to proceed normally on the gate electrode and main source/drain regions (maintaining good contact resistance) while preventing silicide extension only where it would create leakage current paths.
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 silicide-blocking layer effectively prevents the silicide layer from extending onto the source/drain regions, reducing leakage current and enhancing the electrical characteristics of the semiconductor device by maintaining the integrity of the field oxide layer during the fabrication process.
Implementation Method 1
a silicide-blocking layer formed over the border between the field oxide layer and the source/drain regions. The silicide-blocking layer covers edges of the source/drain regions, obstructing the extension of the silicide layer.
Data Source
AI summary
A semiconductor device having a silicide-blocking layer is provided. The device includes a field oxide layer defining an active region, source/drain regions in the active region of a substrate, a gate oxide layer and a gate electrode on the substrate between the source/drain regions, dielectric spacers on sidewalls of the gate electrode, and a silicide layer on both the gate electrode and the source/drain regions. The device also includes the silicide-blocking layer formed over the border between the field oxide layer and the source/drain regions. The silicide-blocking layer covers edges of the source/drain regions, obstructing the extension of the silicide layer.