Serpentine Resistor Dummy Layer Resistance Calibration
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Solution Overview
Problem
Semiconductor resistors in integrated circuits often deviate from their desired resistance values due to manufacturing processes, affecting the accuracy of control circuits.
Innovation Solution
A method involving the use of a serpentine resistor layout with adjustable parameters, where a dummy layer is added to align the physical serpentine resistor's length with the target resistance, ensuring accurate resistance modeling by using equations to derive the serpentine layer's height and adding dummy layers for verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional resistor manufacturing process is used, then the manufacturing process is simple, but the resistance deviates from the desired value
Solution Approach 1:
The resistor is divided into multiple segments arranged in a serpentine pattern, allowing the total resistance to be controlled by adjusting the number and length of segments while maintaining a compact layout that fits within the chip area
Solution Approach 2:
The resistor layout transitions from a simple linear arrangement to a two-dimensional serpentine pattern, enabling the resistor to achieve the desired resistance value within a smaller footprint by utilizing both length and width dimensions of the chip area
2Manufacturing precision
If the serpentine layer height is increased to reduce resistance variation, then the resistance accuracy improves, but the chip area increases
Solution Approach 1:
The method involves calculating and adjusting the serpentine layer height as a critical parameter to compensate for manufacturing variations. By optimizing this geometric parameter, the resistor achieves target resistance values with minimal variation without requiring excessive chip area
Solution Approach 2:
The serpentine layer height is pre-calculated using specific equations that account for manufacturing process variations. This preliminary design adjustment ensures that the fabricated resistor will achieve the desired resistance accuracy without requiring post-manufacturing tuning or additional area
3Measurement precision
If dummy layers are added to verify resistance, then the resistance modeling accuracy improves, but the manufacturing process complexity increases
Solution Approach 1:
Dummy layers are introduced as intermediary structures that facilitate accurate resistance modeling and verification. These layers serve as test structures that allow designers to validate the resistance calculations and adjust the design before full production, ensuring accuracy without complicating the main resistor structure
Data Source
AI summary
A method of forming a serpentine resistor includes: setting a total length of a schematic resistor to make the schematic resistor to have a first resistance according to a sheet resistance; forming, by using a processor, a serpentine layer corresponding to the schematic resistor, forming, by using the processor, a dummy layer over a portion of the serpentine layer to form a modified serpentine layer, measuring, by using the processor, a modified length of the modified serpentine layer, and comparing, by using the processor, the total length and the modified length to generate a comparison result.