Excimer Laser Exposure Control via Parallel E-V Calibration
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Solution Overview
Problem
Existing exposure apparatuses face challenges in precisely controlling the exposure amount and minimizing uneven illuminance in semiconductor device manufacturing, particularly with excimer lasers, due to variations in the E-V characteristic, which can lead to inaccurate dose control and decreased throughput.
Innovation Solution
An exposure apparatus that includes a light source, a detector, and a controller capable of executing parallel calibration processes to determine the E-V characteristic by emitting multiple pulse lights with varying control inputs, allowing for precise control of pulse energy and applied voltage, thereby stabilizing the E-V characteristic and improving dose control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the E-V characteristic is determined using a small number of pulses to maintain throughput, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The system performs preliminary E-V characteristic measurements during idle periods or between production batches, storing the measured characteristics for later use during actual exposure operations. This allows comprehensive measurement using hundreds of pulses without impacting production throughput, as the measurement data is prepared in advance and applied during manufacturing.
2Ease of operation
If the applied voltage is kept constant during exposure to simplify control, then ease of operation is improved, but manufacturing precision deteriorates due to E-V characteristic variations
Solution Approach 1:
The system continuously monitors the actual pulse energy output and compares it against the expected E-V characteristic curve. Based on this feedback, the control system dynamically adjusts the applied voltage to compensate for E-V characteristic shifts caused by gas density changes, temperature variations, or electrode degradation. This maintains precise exposure control while keeping the operational interface simple for users.
Solution Approach 2:
The system changes the operating parameters (applied voltage) based on measured E-V characteristic variations. By storing multiple measurement results taken at different voltages and selecting or interpolating between them, the system adapts to changing laser chamber conditions without requiring manual intervention, thereby maintaining manufacturing precision while simplifying operation.
3Measurement precision
If E-V measurement is performed separately from the exposure process to ensure accuracy, then measurement precision is improved, but productivity deteriorates due to additional time required
Solution Approach 1:
The system merges the E-V measurement function with the exposure process by utilizing the same laser pulses for both measurement and production purposes. During exposure operations, a portion of the pulse data is simultaneously used to update and refine the E-V characteristic model. This integration allows the system to maintain accurate measurement data without requiring separate measurement time, thereby preserving both measurement precision and productivity.
4Measurement precision
If hundreds of pulses are used to average laser energy variation for precise E-V measurement, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system performs comprehensive E-V measurements using hundreds of pulses during idle periods, maintenance windows, or between production batches. These preliminary measurements establish accurate baseline characteristics that are then reused during actual production. This approach allows the system to gather sufficient statistical data for high-precision measurements without incurring time penalties during revenue-generating production operations.
Solution Approach 2:
The system continuously accumulates measurement data from every laser pulse during normal operation, rather than performing discrete batch measurements. By continuously updating the E-V characteristic model with each pulse while maintaining production, the system achieves high measurement precision over time without interrupting or slowing down the production flow, thereby eliminating the trade-off between measurement time and accuracy.
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 solution enables precise control of the exposure amount, minimizes uneven illuminance, and enhances throughput by accurately determining the E-V characteristic using hundreds of pulses and optional voltage adjustments, improving the yield in semiconductor device manufacturing.
Implementation Method 1
the exposure apparatus using an excimer laser as an exposure light adjusts an exposure amount by adjusting an applied voltage to a laser chamber in a light source and controlling pulse energy of the laser
Implementation Method 2
a detector configured to detect a light quantity of the pulse light
Data Source
AI summary
An exposure apparatus is provided with a light source for emitting pulse light and exposes a substrate via to the pulse light an original. Further, the exposure apparatus comprises a detection unit for detecting the light quantity of the pulse light and a controller for controlling the light source and the detection unit. Here, the controller is configured to execute a first calibration process for obtaining a relation between a control input to the light source and a light quantity of a pulse light from the light source, based on light quantities of a plurality of pulse lights detected by the detector by causing the light source to emit the plurality of the pulse lights with a plurality of the control input, in parallel with execution of a second calibration process which is different from the first calibration process and executed using the plurality of pulse lights.