Overlapping IC Stressors for Package Stress Compensation
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Solution Overview
Problem
Integrated circuits face challenges in maintaining consistent transistor performance due to varying stress imparted by package structures, which can counter or add to the stress provided by stressors, leading to non-uniform carrier mobility and drive current variations across the circuit.
Innovation Solution
The use of overlapping compressive and tensile stressors directly over active transistor regions allows for adjustment of stress applied to the channel region, compensating for stress imparted by package structures without requiring additional masks or implantation steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single type of stressor (compressive or tensile) is used over the active region, then the manufacturing process is simpler, but the stress applied to the channel region cannot be precisely tuned to compensate for package structure stress
Solution Approach 1:
The patent combines both compressive and tensile stressors in a single integrated structure over the active region. The first stressor (e.g., compressive) and second stressor (e.g., tensile) are formed in overlapping regions, allowing their stress effects to combine and provide precise stress tuning capability while maintaining a relatively simple manufacturing process using standard semiconductor fabrication techniques
2Manufacturing precision
If overlapping compressive and tensile stressors are used, then stress tuning precision is improved, but the device structure becomes more complex
Solution Approach 1:
The patent applies different stressor types (compressive and tensile) to different local regions of the active area. By spatially distributing the first and second stressors across overlapping regions, each stressor type provides its specific stress effect locally, while the overall structure achieves precise stress tuning. This localized approach enables complex stress control without requiring the entire device structure to be complex
3Reliability
If stressors are added to compensate for package structure stress, then transistor performance consistency is improved, but the manufacturing process requires additional steps
Solution Approach 1:
The patent incorporates the compensatory stressors as integral parts of the transistor fabrication process itself, forming the first and second stressors during the same manufacturing steps that create the transistor structures. This preliminary integration means the stress compensation features are built in from the start rather than added as separate post-processing steps, maintaining reliability while avoiding additional manufacturing complexity
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 precise tuning of stress in channel regions to maintain consistent transistor performance across the integrated circuit, reducing variations in carrier mobility and drive current.
Implementation Method 1
A stressor is a dielectric structure that is formed to induce a stress (either compressive or tensile) on surrounding structures of an integrated circuit
Data Source
AI summary
An integrated circuit includes a compressive stressor and a tensile stressor, each located directly over an active region of a transistor, where a portion of the compressive stressor and a portion of the tensile stressor directly overlap with each other. In some embodiments, utilizing a compressive stressor and tensile stressor located directly over an active region with overlapping portions may allow for an adjustment of the stress applied to a channel region of a transistor to compensate for stress imparted by package structures.