CMP Acoustic Monitoring for Precise Film Thickness Control
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Solution Overview
Problem
In semiconductor manufacturing, existing methods for controlling the thickness of films during polishing lack accuracy, especially for multi-layer structures and insulating films, due to complexity in apparatus structure and interference from abrasive grains or shavings, which affects measurement precision.
Innovation Solution
A semiconductor manufacturing apparatus that includes a rotatable top ring, a turntable with a polishing pad, a sound measuring unit, and a calculation unit to calculate polishing amount based on sound pressure differences, using FFT processing and regression models to predict sound pressure and correct for variations, allowing for precise control of polishing time and material-specific unit polishing amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical methods are used to measure polishing amount, then measurement can be performed, but measurement precision deteriorates due to interference from abrasive grains or shavings
Solution Approach 1:
The patent replaces optical measurement methods with acoustic measurement methods. A sound sensor detects sound pressure changes during polishing, and a calculation unit determines the polishing amount based on these acoustic signals. This substitution eliminates the interference problem caused by abrasive grains affecting optical measurements, as acoustic waves are not blocked or scattered by the same materials that interfere with light.
2Manufacturing precision
If predetermined methods are used to measure polishing amount, then measurement is possible, but accuracy is insufficient for high-precision film thickness control
Solution Approach 1:
The system continuously monitors sound pressure during polishing and uses this real-time data to calculate the polishing amount. The calculation unit processes the acoustic signals and provides feedback information about the actual polishing progress, enabling precise control of film thickness. This feedback mechanism allows for dynamic adjustment and ensures high manufacturing precision for multi-layer structures and insulating films.
Solution Approach 2:
The patent changes the measurement parameter from optical properties to acoustic properties. By measuring sound pressure changes instead of using optical methods, the system achieves more accurate polishing amount determination that is not affected by the optical interference problems encountered with traditional methods, thereby improving film thickness control accuracy.
3Measurement precision
If sound pressure measurement is used to calculate polishing amount, then measurement precision improves, but apparatus complexity increases due to FFT processing and regression models
Solution Approach 1:
The patent replaces complex optical measurement systems with a simpler acoustic measurement system. The sound sensor and calculation unit provide a more straightforward measurement approach that achieves high precision without the complex optical paths, interferometers, or sophisticated optical components required by traditional optical methods. The acoustic system inherently avoids many of the complexity issues associated with optical setups.
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
Enables accurate calculation of polishing amounts regardless of film type, simplifies apparatus structure, and maintains high measurement precision even with varying materials, avoiding complications from optical methods and abrasive interference.
Implementation Method 1
a sound measuring unit that measures a first sound generated during the polishing, and a first calculation unit that calculates a polishing amount of the film based on a first sound pressure of the first sound
Data Source
AI summary
A semiconductor manufacturing apparatus includes a first top ring that is rotatable and configured to hold a wafer, a first turntable that is rotatable and has a polishing pad for performing polishing of a film formed on the wafer, a sound measuring unit (sensor) that measures a first sound generated during the polishing, and a first calculation unit (controller) that calculates a polishing amount of the film based on a first sound pressure of the first sound, a polishing amount per unit time of the polishing, and a time of the polishing.