CMP Pad Elastic Modulus Feedback Control
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Solution Overview
Problem
Conventional CMP polishing methods fail to adjust polishing conditions based on the elastic modulus of the polishing pad, leading to uneven polishing results, such as rounded edges and erosion, due to the pad's varying stiffness influenced by thickness, liquid absorption, and temperature.
Innovation Solution
A polishing method and apparatus that measures the elastic modulus of the polishing pad in real-time and adjusts polishing conditions, including pressure and temperature, to maintain optimal polishing performance by using an elastic modulus measuring device and a polishing condition adjustor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing is performed without adjusting conditions based on elastic modulus, then the polishing process is simple, but polishing uniformity deteriorates due to pad softening
Solution Approach 1:
The patent implements a feedback mechanism where the elastic modulus of the polishing pad is measured in real-time during polishing operations. Based on these measurements, the polishing conditions (pressure, speed, liquid flow) are automatically adjusted to compensate for pad softening, thereby maintaining consistent polishing quality throughout the pad's service life
Solution Approach 2:
The patent dynamically changes polishing parameters (applied pressure, relative speed, polishing liquid flow rate) based on the measured elastic modulus of the polishing pad. As the pad softens (elastic modulus decreases), the system adjusts parameters to maintain optimal polishing performance, preventing rounded edges and erosion
2Productivity
If polishing pad is used for extended period, then productivity increases, but polishing quality deteriorates due to elastic modulus change
Solution Approach 1:
The system continuously monitors the elastic modulus of the polishing pad during extended use and provides real-time feedback to adjust polishing conditions. This allows the pad to be used for extended periods while maintaining consistent polishing quality by compensating for gradual softening through dynamic parameter adjustment
Solution Approach 2:
The patent transforms the static polishing process into a dynamic one where polishing parameters are continuously adjusted based on real-time elastic modulus measurements. This enables the system to adapt to changing pad properties during extended operation, maintaining polishing quality throughout the pad's entire service life
3Productivity
If polishing pressure is increased to compensate for pad softening, then polishing rate is maintained, but rounded edge and erosion worsen
Solution Approach 1:
The patent adjusts multiple polishing parameters simultaneously based on elastic modulus measurements, not just pressure. The system optimizes the combination of pressure, relative speed, and polishing liquid flow rate to maintain polishing rate while preventing rounded edge and erosion that would result from pressure increases alone
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 ensures a consistent and high-quality polishing process by accurately reflecting the pad's elastic modulus in adjustments, preventing rounded edges and erosion, and maintaining uniformity across the wafer surface.
Implementation Method 1
The elastic modulus of the polishing pad is a value of physical property representing a difficulty of being deformed when a force is applied to the polishing pad
Implementation Method 2
the polishing liquid gradually soaks into cells formed in the polishing pad
Implementation Method 3
as the temperature of the polishing pad increases, the polishing pad becomes soft
Data Source
AI summary
A polishing apparatus polishes a substrate by moving the substrate and a polishing pad relative to each other. The apparatus includes: an elastic modulus measuring device configured to measure an elastic modulus of the polishing pad, and a polishing condition adjustor configured to adjust polishing conditions of the substrate based on a measured value of the elastic modulus. The polishing conditions include pressure of a retaining ring, arranged around the substrate, exerted on the polishing pad and a temperature of the polishing pad.