Rotating Wafer Etching Thickness Control via Periodic Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor manufacturing methods fail to accurately detect etching progress on rotating wafers due to thickness non-uniformity, leading to significant differences between finished and target thickness values.
Innovation Solution
The semiconductor manufacturing equipment and method incorporate a rotation mechanism, etching mechanism, thickness measurement function, etching control function, and thickness calculation function to generate time-dependent thickness data and calculate representative values for each unit period, ensuring precise detection of etching progress and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If film thickness measurement is performed on a rotating substrate using a diffuser to stabilize measurement at each moment, then measurement stability at each time point is improved, but measurement precision of etching progress is worsened due to variation depending on when the rotating wafer is measured
Solution Approach 1:
The patent applies periodic action by defining a 'unit period' corresponding to one complete rotation cycle of the wafer and performing thickness calculations at regular intervals synchronized with the rotation. This ensures that measurements are taken systematically throughout each rotation cycle, capturing the thickness variation pattern and enabling accurate determination of average thickness and etching progress, thereby resolving the contradiction between momentary measurement stability and overall etching progress detection accuracy.
2Productivity
If the wafer is rotated during etching to enable continuous measurement, then productivity is improved, but measurement precision is worsened due to thickness non-uniformity across the wafer surface
Solution Approach 1:
The patent implements periodic action by synchronizing thickness measurements with the periodic rotation of the wafer. By calculating representative thickness values at regular intervals corresponding to complete rotation cycles, the system maintains continuous etching capability while accurately capturing thickness information despite the rotating motion and inherent non-uniformity, thus resolving the contradiction between productivity and measurement precision.
3Device complexity
If thickness measurement is performed at single time points during wafer rotation, then device complexity is reduced, but measurement precision of average thickness is worsened due to sampling variation
Solution Approach 1:
The patent applies periodic action by performing thickness measurements at multiple discrete time points synchronized with wafer rotation cycles and calculating representative values through systematic averaging. This approach maintains relatively simple measurement equipment while significantly improving average thickness accuracy by capturing the periodic variation pattern and computing mean values over complete rotation cycles, thereby resolving the contradiction between device simplicity and measurement precision.
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 approach allows for high-precision detection of etching progress and reduces the difference between finished and target thickness values by equalizing weighting values measured about the rotational axis, thereby improving etching accuracy.
Implementation Method 1
The light emitting unit irradiates the target film to be measured with light. The light receiving unit receives reflected light from the target film to be measured.
Implementation Method 2
The diffuser which is disposed on the light receiving path leading from the target film to be measured to the above light receiving unit, diffuses the reflected light from the target film to be measured and emits toward the light receiving unit after homogenization.
Data Source
AI summary
A rotation mechanism is configured to rotate a wafer including an etched region which is to be etched at least partially. An etching mechanism etches the etched region. A thickness measurement function is configured to generate time-dependent thickness data by measuring a thickness of the etched region. An etching control function is configured to stop the etching mechanism when a representative value of thickness of the etched region reaches a target thickness value. A thickness calculation function is configured to calculate the representative value of thickness for each unit period in which the wafer is rotated N times, where N is a natural number, based on measurement values of the time-dependent thickness data in a measurement section being a range measured during the unit period.