SiC Device Compensation for Wafer Position Variations
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Solution Overview
Problem
Devices fabricated on silicon carbide (SiC) wafers exhibit property variations due to lateral inhomogeneities, leading to inconsistent device performance and manufacturing challenges, as epitaxial layer growth and doping can differ across the wafer, affecting threshold voltages and drain currents.
Innovation Solution
A method is developed to compensate for these variations by determining the output differences between devices at different wafer positions, altering the first device's voltage input or adding a current source to match the output of a second device, thereby addressing differences in chemical and threshold voltage properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If devices are fabricated on different portions of the wafer, then manufacturing productivity is improved, but device property uniformity deteriorates due to lateral inhomogeneities in epitaxial layer growth and doping
Solution Approach 1:
The patent applies local quality by implementing position-dependent compensation parameters tailored to specific regions of the wafer. Different compensation values are applied to devices at different radial positions, accounting for the lateral inhomogeneities in epitaxial layer growth and doping that occur at different wafer locations. This regional customization allows each device to be compensated according to its specific position-related characteristics.
Solution Approach 2:
The patent employs parameter changes by systematically varying compensation parameters based on device position. The compensation mechanism adjusts electrical parameters (such as threshold voltage or bias conditions) according to the radial distance from the wafer center, thereby counteracting the position-dependent property variations introduced during fabrication.
2Productivity
If epitaxial layer growth is performed across the entire wafer, then manufacturing efficiency is improved, but device performance consistency deteriorates due to variations in layer doping and thickness
Solution Approach 1:
The patent uses parameter changes by implementing position-dependent compensation that adjusts device operating parameters based on their location on the wafer. This compensation accounts for the variations in epitaxial layer doping and thickness that occur during single-wafer processing, thereby maintaining performance consistency across all devices fabricated in the same batch.
Solution Approach 2:
The patent implements feedback mechanisms that use measured or characterized position-dependent property variations to adjust compensation parameters. By incorporating feedback from wafer position information and property measurements, the system can dynamically adjust compensation to maintain consistent device performance despite variations in epitaxial layer characteristics.
3Productivity
If devices are processed in batches across the wafer, then manufacturing throughput is improved, but control over individual device properties deteriorates
Solution Approach 1:
The patent applies local quality by implementing position-specific compensation parameters that are assigned to devices based on their coordinates on the wafer. This allows each device to receive customized compensation tailored to its local environment during batch processing, thereby maintaining precise control over individual device properties even when processed together in batches.
Data Source
AI summary
Methods and devices are disclosed for compensating for device property variations across a wafer. The method comprises determining an output of a first device based on an input and determining an output of a second device based on the input. The second device is located at a different position with respect to a center of the wafer than a position of the first device with respect to the center of the wafer. The method further comprises determining a difference between the output of the first device and the output of the second device, the difference arising at least in part from the difference in position of the first and second devices. The method further comprises altering the first device such that the output of the first device based on the input substantially matches the output of the second device based on the input.