Nitrogen-Modified Silicon Substrate for Strained Transistor Integrity
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Solution Overview
Problem
As semiconductor devices are scaled down to increase packing density, reduced transistor dimensions lead to slower operations and performance issues due to reduced carrier mobility and potential plastic deformation of the substrate from strain-inducing layers.
Innovation Solution
Incorporating nitrogen into the substrate, particularly in source/drain regions, to enhance yield strength and form a strain-inducing layer that increases carrier mobility while preventing substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistor dimensions are reduced to increase packing density, then device density and effective yield are improved, but carrier mobility decreases leading to slower operation
Solution Approach 1:
The patent changes the physical state of the substrate by incorporating nitrogen to modify its elastic properties. This parameter change allows the substrate to withstand strain from strain-inducing layers even at reduced dimensions, maintaining carrier mobility while enabling higher device density
Solution Approach 2:
The patent creates a composite structure by incorporating nitrogen into the semiconductor substrate, forming a nitrogen-modified substrate that combines the electrical properties of silicon with the enhanced mechanical properties of nitrogen-strengthened lattice structure
2Speed
If strain-inducing layers are applied to enhance carrier mobility, then transistor operation speed is improved, but plastic deformation of the substrate occurs
Solution Approach 1:
The patent applies nitrogen incorporation beforehand to strengthen the substrate's elastic properties before applying strain-inducing layers. This preparatory measure cushions the substrate against plastic deformation when strain layers are subsequently applied to enhance carrier mobility
Solution Approach 2:
The patent changes the mechanical parameters of the substrate by incorporating nitrogen, which modifies the elastic properties and yield strength. This parameter change allows the substrate to tolerate the stress from strain-inducing layers without permanent deformation, maintaining both speed and reliability
3Reliability
If nitrogen is incorporated into the substrate to enhance yield strength, then substrate integrity is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent merges the nitrogen incorporation step with existing source/drain extension region formation or source/drain region formation processes. By combining these operations, the manufacturing process complexity is minimized while still achieving the desired substrate strengthening effect
Solution Approach 2:
The patent utilizes the existing manufacturing infrastructure and process steps to incorporate nitrogen, allowing the process to serve itself rather than requiring entirely new equipment or methods. The nitrogen is incorporated during routine fabrication steps already present in the manufacturing flow
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 allows for scaled-down transistor dimensions with improved carrier mobility and operational speed while maintaining substrate integrity, mitigating plastic deformation and enhancing transistor performance.
Implementation Method 1
incorporating nitrogen into the substrate, and more particularly into source/drain extension regions and/or source/drain regions of the transistor
Implementation Method 2
A strain inducing layer is formed over the transistor to apply a strain thereto to alter transistor operating characteristics, and more particularly to enhance the mobility of carriers within the transistor
Data Source
Figure 1~2
Figure 3~4
AI summary
A transistor (200) is fabricated upon a semiconductor substrate (202), where the yield strength or elasticity of the substrate is enhanced or otherwise adapted. A strain inducing layer (236) is formed over the transistor to apply a strain thereto to alter transistor operating characteristics, and more particularly to enhance the mobility of carriers within the transistor. Enhancing carrier mobility allows transistor dimensions to be reduced while also allowing the transistor to operate as desired. However, high strain and temperature associated with fabricating the transistor result in deleterious plastic deformation. The yield strength of the silicon substrate is therefore adapted by incorporating nitrogen into the substrate, and more particularly into source/drain extension regions (220,222) and/or source/drain regions (228,230) of the transistor. The nitrogen can be readily incorporated during transistor fabrication by adding it as part of source/drain extension region formation and/or source/drain region formation. The enhanced yield strength of the substrate mitigates plastic deformation of the transistor due to the strain inducing layer.