CMP Notch-Finding Station With Liquid Column Optics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing chemical mechanical polishing (CMP) systems face inaccuracies in detecting substrate notches due to light scattering from liquid droplets with different refractive indices in wet environments, leading to inconsistent substrate orientation and increased manufacturing costs.
Innovation Solution
A polishing apparatus with a notch-finding station that uses a liquid column to direct a light beam through a uniform medium towards the substrate, enabling precise notch detection without removing the substrate from the carrier, and incorporating a controller to manage liquid flow rates for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light beam is used to detect substrate notch in a wet environment, then notch detection can be performed, but light scattering from liquid droplets causes measurement inaccuracies
Solution Approach 1:
A liquid column is introduced as an intermediary medium between the light source and the substrate. This liquid column provides a uniform refractive index environment that eliminates light scattering from liquid droplets, thereby improving notch detection accuracy while maintaining the wet polishing environment
Solution Approach 2:
The refractive index of the medium through which light travels is changed from variable (liquid droplets in air) to uniform (continuous liquid column). This parameter change eliminates light scattering and improves measurement precision
2Measurement precision
If the substrate is removed from the carrier for notch detection, then detection accuracy may improve, but processing time increases and operational complexity increases
Solution Approach 1:
The liquid column-based detection system is designed to work with the substrate remaining on the carrier, making the detection process universal and compatible with the existing carrier-based polishing workflow. This eliminates the need for additional substrate handling steps
3Reliability
If liquid flow rate is increased to maintain liquid column stability, then detection reliability improves, but liquid consumption increases
Solution Approach 1:
The liquid flow rate is made dynamically adjustable rather than fixed. The system can optimize flow rate based on operational conditions, maintaining liquid column stability during detection while reducing liquid consumption during idle periods
Solution Approach 2:
The liquid flow rate parameter is optimized to the minimum value required to maintain liquid column stability. This reduces liquid consumption while preserving detection reliability
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
The solution provides high-precision notch detection in wet environments, reducing manufacturing costs by maintaining substrate orientation consistency and enhancing the reliability of polishing operations.
Implementation Method 1
an optical fiber extending through a floor of the housing and positioned to direct a light beam through the liquid column onto the substrate when held by the carrier at the notch finding station and to receive reflections of the light beam from the substrate
Implementation Method 2
light scattering from liquid droplets with different refractive indices in wet environments
Data Source
AI summary
A polishing apparatus has a polishing station, a notch finding station, and a substrate handling system to move a substrate therebetween. The notch finding station includes a housing having an internal volume that provides forms a reservoir with a floor, a ceiling, and first sidewalls that extend from the floor to the ceiling. An aperture extends through the ceiling of the reservoir and a side-passage extends laterally from a region of the reservoir below the aperture to an entry port such that a liquid injected through the entry port flows emerges from the aperture to form a liquid column. An optical fiber extends through a floor of the reservoir and is positioned to direct a light beam through the aperture and through the liquid column onto a substrate when held at the notch finding station and to receive reflections of the light beam from the substrate.