Substrate Alignment via Thickness-Based Process Center Offset Correction
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Solution Overview
Problem
In plasma processing for semiconductor manufacturing, aligning substrates to the process center is challenging due to discrepancies between the hardware center and the process center, leading to misalignment and defects, which existing methods fail to address effectively.
Innovation Solution
A method is developed to determine the process center by measuring substrate thickness at various orientations and radial distances, creating an off-centered plot, and applying a curve-fitting equation to calculate the substrate offset, allowing robotic arms to accurately position substrates over the process center for improved uniformity and reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If substrates are aligned to the hardware center (center of substrate chuck), then alignment precision is improved, but process uniformity deteriorates due to misalignment with the process center
Solution Approach 1:
The patent replaces mechanical alignment methods (physical centering on hardware center) with a computational approach. Sensors measure substrate position and thickness, a controller calculates the process center based on measured data, and the system computationally determines alignment corrections. This substitution of mechanical centering with measurement-based computational centering resolves the contradiction by achieving both precise alignment and process uniformity.
Solution Approach 2:
The patent implements a feedback loop where sensors continuously measure substrate position and thickness at multiple locations, the controller processes this data to determine the process center, and the system adjusts substrate alignment accordingly. This closed-loop feedback enables dynamic correction of alignment errors, maintaining both alignment precision and process uniformity despite variations in substrate placement.
2Measurement precision
If alignment fixtures or guided robotic arms are used to position substrates, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The patent enables the substrate processing system to self-align by using sensors to measure substrate position and thickness, automatically calculating the process center, and determining alignment corrections without requiring external alignment fixtures or complex mechanical guidance systems. The system serves its own alignment needs through measurement and computation, reducing device complexity while maintaining precision.
3Manufacturing precision
If substrates are misaligned from the process center, then manufacturing precision deteriorates, but device complexity remains low with simple hardware centering
Solution Approach 1:
The patent changes the alignment parameter from fixed hardware center coordinates to a dynamically calculated process center based on measured substrate thickness and position data. By transforming the alignment reference from a static mechanical point to a computed parameter derived from sensor measurements, the system achieves improved process uniformity without requiring complex mechanical alignment hardware.
Data Source
AI summary
A method for aligning a substrate to a process center of a support mechanism is provided. The method includes determining substrate thickness after substrate processing at a plurality of orientations and at a plurality of radial distances from a geometric center of the substrate. The method also includes deriving a set of process rate values from substrate thickness and process duration. The method further includes creating for a process rate an off-centered plot, which represents a substantially concentric circle whose points are a circumference of the off-centered plot having substantially the first process rate. The method yet also includes applying a curve-fitting equation to the off-centered plot to determine a set of parameters. The method yet further includes teaching a set of robot arms the set of parameters, thereby enabling the set of robot arms to align another substrate that is supported by the support mechanism with the process center.