Inter-Step Feedforward Control for Semiconductor Wafer Processing
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Solution Overview
Problem
Existing semiconductor manufacturing processes lack efficient methods for feedforward control between consecutive processing steps, leading to inefficiencies and inaccuracies in the formation of semiconductor devices.
Innovation Solution
A method and system for inter-step feedforward control involving metrology after a first processing step to generate correctables for a subsequent processing step, using imaging or scatterometry-based metrology tools to adjust processing tool settings, optimizing each step based on previous step measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional process control methods are used without feedforward control, then the manufacturing process is simpler, but the manufacturing precision and accuracy of semiconductor devices deteriorate
Solution Approach 1:
The patent performs metrology measurements after the first processing step to generate correctables before the second processing step is executed. This preliminary measurement and correction generation enables feedforward control that improves manufacturing precision by anticipating and correcting errors before they propagate to subsequent layers.
Solution Approach 2:
The patent implements a feedback loop where metrology measurements of misregistration are used to generate correctables that adjust processing tool settings for subsequent steps. This closed-loop feedback system continuously optimizes manufacturing precision by using actual measurement data to refine process parameters in real-time.
2Manufacturing precision
If feedforward control with metrology is implemented between processing steps, then the manufacturing precision improves, but the productivity decreases due to additional measurement time
Solution Approach 1:
Metrology measurements are performed immediately after the first processing step while wafers are still in the processing sequence, generating correctables before the second step begins. This preliminary action approach minimizes idle time and keeps the production flow continuous, reducing the impact on overall productivity.
Solution Approach 2:
The patent maintains continuous wafer processing by overlapping metrology measurements with processing operations. While some wafers undergo measurement and correction generation, other wafers continue through processing steps, ensuring the production line operates continuously without significant interruptions to throughput.
3Manufacturing precision
If metrology is performed on every wafer in a lot, then the manufacturing precision maximizes, but the loss of time increases due to extensive measurement requirements
Solution Approach 1:
The patent applies feedforward control selectively to specific wafers within a lot based on their individual metrology results. By identifying and correcting only the wafers that require adjustment rather than uniformly processing every wafer, the system achieves high manufacturing precision for affected wafers while minimizing the total time lost to measurements.
Solution Approach 2:
The patent performs metrology on representative samples or selected wafers within each lot rather than every single wafer. This partial measurement approach generates sufficient correctables to adjust processing parameters for the entire lot, achieving acceptable manufacturing precision while significantly reducing the time investment compared to measuring every wafer.
4Manufacturing precision
If correctables are generated and applied to adjust subsequent processing steps, then the manufacturing precision improves, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent introduces correctables as an intermediary element that bridges metrology measurements and processing tool adjustments. These correctables serve as a standardized data format that translates measurement results into actionable correction parameters, simplifying the control system architecture by providing a clear interface between measurement and execution subsystems.
Solution Approach 2:
The patent adjusts processing tool settings by modifying specific parameters based on generated correctables, such as alignment offsets, focus adjustments, or exposure dose changes. By changing only the necessary process parameters rather than reconfiguring entire processing sequences, the system achieves high manufacturing precision while keeping the control mechanism relatively simple and focused.
Data Source
AI summary
A method for process control in the manufacture of semiconductor devices including performing metrology on at least one semiconductor wafer included in a given lot of semiconductor wafers, following processing of the at least one semiconductor wafer by a first processing step, generating, based on the metrology, at least one correctable to a second processing step subsequent to the processing step and adjusting, based on the correctable, performance of the second processing step on at least some semiconductor waters of the given lot of semiconductor wafers.