Silicide Layer Formation in Semiconductor Devices
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Solution Overview
Problem
Existing methods for forming a silicide layer in semiconductor devices, particularly in MOS image sensors, face challenges such as incomplete reaction, metal contamination, and characteristic degradation due to ion implantation through nitride blocking layers, which increase manufacturing steps and complexity.
Innovation Solution
A semiconductor device and manufacturing method where a silicide layer is formed only in the peripheral circuit region by forming a gate electrode on a substrate with a gate insulating layer, a first impurity region is created before forming a nitride blocking layer, and a sidewall including the nitride layer is formed to prevent ion implantation in the imaging region, reducing manufacturing steps and preventing characteristic degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a silicide layer is formed in the imaging region to improve transistor operation speed, then the operation speed of the peripheral transistor is improved, but metal contamination and white spots occur due to incomplete reaction and diffusion of unreacted refractory metal
Solution Approach 1:
The substrate is divided into two distinct regions: an imaging region where silicide layers are not formed, and a peripheral circuit region where silicide layers are formed. This spatial segmentation allows the peripheral transistor to achieve high-speed operation through silicide formation while preventing metal contamination and white spots in the imaging region by excluding silicide formation there.
Solution Approach 2:
Different regions of the substrate are given different properties: the imaging region is kept free of silicide layers to maintain high image quality and avoid contamination, while the peripheral circuit region is equipped with silicide layers to enhance transistor operation speed. This local differentiation resolves the contradiction by applying the silicide formation treatment only where it is beneficial.
2Object-affected harmful factors
If a blocking layer is formed to prevent refractory metal from contacting silicon substrate in the imaging region, then metal contamination is prevented, but the number of manufacturing steps increases
Solution Approach 1:
Instead of forming a blocking layer across the entire substrate, the substrate is segmented into imaging and peripheral circuit regions. The silicide formation process is selectively applied only to the peripheral circuit region, eliminating the need for additional blocking layers in the imaging region and reducing manufacturing steps while still preventing metal contamination.
Solution Approach 2:
The blocking layer function is extracted and replaced by spatial selective processing. Rather than adding a blocking layer to prevent contamination, the invention extracts the contamination risk by excluding the silicide formation process from the imaging region entirely, thereby preventing contamination without adding manufacturing steps.
3Manufacturing precision
If ion implantation is performed through a nitride blocking layer to form impurity regions, then source and drain regions are formed, but characteristic degradation occurs due to ion implantation through the blocking layer
Solution Approach 1:
Impurity regions are formed by ion implantation before the nitride blocking layer is deposited. This preliminary action allows complete ion implantation without the blocking layer interfering, preventing characteristic degradation while still enabling proper source and drain region formation. The nitride layer is then formed to serve as a blocking layer for subsequent silicide formation processes.
Solution Approach 2:
The conventional sequence is inverted: instead of forming the nitride blocking layer first and then performing ion implantation through it, the ion implantation is performed first to form impurity regions, and then the nitride blocking layer is formed. This inversion eliminates the harmful effect of ion implantation through the blocking layer while maintaining the beneficial blocking function for silicide formation.
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 approach enables the production of high-quality semiconductor devices and solid-state imaging apparatuses with improved operation speed and reduced manufacturing complexity by preventing characteristic degradation and metal contamination, while maintaining the stability of the silicide layer formation process.
Implementation Method 1
a first impurity region is created before forming a nitride blocking layer, and a sidewall including the nitride layer is formed to prevent ion implantation in the imaging region
Implementation Method 2
A silicide layer is formed by forming a layer of a refractory metal on the surface of a source region or a drain region and reacting silicon and the refractory metal
Data Source
AI summary
A semiconductor device includes a gate electrode formed on a substrate with a gate insulating layer in between, an insulating layer of property and thickness that allow for a silicide block formed in a first region of the substrate so as to cover the gate electrode, a sidewall formed to at least partly include the insulating layer at a side of the gate electrode, a first impurity region formed by implantation of a first impurity in a peripheral region of the gate electrode formed in the first region of the substrate before the insulating layer is formed, a second impurity region formed by implantation of a second impurity in a peripheral region of the sidewall of the gate electrode formed in a second region of the substrate after the sidewall is formed, and a silicide layer formed on a surface of the second impurity region of the substrate.