Analog Circuit Hotspot Detection and Layout Correction
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Solution Overview
Problem
Current DFM solutions lack tools for detecting and correcting electrical hotspots in analog and mixed-signal designs, which are critical for improving manufacturing yield due to their sensitivity to physical layout effects and variations in manufacturing processes, especially at technology nodes below 65 nm.
Innovation Solution
An electrical hotspot detection and correction method that extracts layout parameters, computes electrical parameter variations, and performs sensitivity analysis to generate repair hints, adjusting the layout design using a smart cost-function technique to address mechanical stress, lithography, and proximity effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional trial-and-error design cycles are used to verify circuit performance against process variations, then circuit reliability can be improved, but design productivity deteriorates due to high computational expense and multiple design corners
Solution Approach 1:
The patent performs preliminary extraction of layout parameters and computation of electrical parameter variations before final circuit verification. By calculating stress parameters, lithography parameters, and proximity effect parameters in advance, the system prepares data structures that enable faster subsequent verification across multiple design corners, reducing the computational burden during iterative design cycles
Solution Approach 2:
The patent replaces conventional SPICE-based electrical simulation with a physics-based computational model that directly calculates electrical parameter variations from layout geometry. This substitution uses analytical models for stress effects, lithography variations, and proximity effects instead of time-consuming circuit simulation, dramatically reducing computational expense while maintaining accuracy
2Manufacturing precision
If extensive simulation runs are performed to check schematics against potential process variations, then manufacturing precision can be improved, but loss of time increases due to computational complexity
Solution Approach 1:
The patent extracts and analyzes only the critical layout parameters that influence electrical performance under process variations. By identifying and focusing on stress parameters, lithography parameters, and proximity effect parameters rather than simulating all circuit behaviors, the system achieves manufacturing precision analysis with significantly reduced computational time
Solution Approach 2:
The patent changes the approach from simulating circuit electrical behavior to directly computing electrical parameter variations (such as threshold voltage, mobility, and capacitance) from layout geometry and process parameters. This parameter-based computation method maintains manufacturing precision while reducing simulation time by avoiding full circuit analysis
3Reliability
If layout parameters are extracted and electrical parameter variations are computed to identify hotspots, then reliability can be improved, but device complexity increases due to multiple parameter extraction and sensitivity analysis
Solution Approach 1:
The patent segments the electrical parameter analysis into distinct components: stress effect parameters, lithography effect parameters, and proximity effect parameters. Each segment is computed independently using specialized formulas, making the complex analysis manageable and systematic while improving reliability through comprehensive coverage of all variation sources
4Manufacturing precision
If sensitivity analysis is performed to generate repair hints and adjust layout design, then manufacturing yield can be improved, but ease of operation deteriorates due to automated correction complexity
Solution Approach 1:
The patent implements an automated system that performs sensitivity analysis, generates repair hints, and adjusts layout design without manual intervention. The system self-corrects electrical hotspots by automatically modifying layout parameters based on computed sensitivity data, improving manufacturing yield while maintaining ease of operation through full automation of the correction process
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 automatically identifies and corrects electrical hotspots, improving manufacturing yield by ensuring that circuit designs meet electrical constraints, reducing computational complexity and trial-and-error cycles in the design process.
Implementation Method 1
Shallow trench isolation (STI) in the CMOS process may induce mechanical stresses on the transistor channel. These mechanical stresses alter the transistor channel mobility (μ) and voltage threshold (Vth).
Implementation Method 2
Lithography variations, for example, can have a significant impact on device dimensions such as length (L), width (W), area drain capacitance (AD), and area source capacitance (AS).
Implementation Method 3
In technology nodes at 65 nm and below, geometrical and electrical parameters of a transistor are also affected by its neighboring devices in the layout design. This is sometimes referred to as proximity effects.
Data Source
AI summary
Aspects of the invention relate to techniques for detecting and correcting electrical hotspots in a layout design for a circuit design comprising an analog circuit. Layout parameters for device instances associated with electrical constraints are first extracted. Based on the extracted layout parameters, electrical parameter variations for the device instances may be computed to identify one or more electrical hotspots in the layout design. A sensitivity analysis of the one or more electrical hotspots is performed to generate repair hints. Based on the repair hints, the layout design is adjusted.