Polishing Apparatus Spectrum Classification for Substrate Monitoring
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Solution Overview
Problem
Existing substrate polishing technologies face challenges in accurately monitoring the progress of polishing and detecting the polishing end point due to variations in the spectrum of reflected light from regions with different structures on the substrate surface, leading to inconsistent film-thickness information and inaccurate polishing profiles.
Innovation Solution
A method and apparatus that classify the spectrum of reflected light from different regions on the substrate based on shape, intensity, or frequency components, allowing for separate monitoring of polishing progress and end-point detection using distinct algorithms tailored to each region's characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is applied to multiple measurement points on the substrate surface to obtain accurate polishing profile, then measurement precision is improved, but the spectrum variation from different structured regions causes loss of information and inaccurate results
Solution Approach 1:
The substrate surface is divided into multiple measurement zones (central zone, intermediate zone, edge zone) with different structural characteristics. Each zone is monitored separately using dedicated light sources and light receivers positioned at corresponding locations on the polishing table, allowing region-specific polishing progress tracking without spectrum confusion
Solution Approach 2:
Different measurement strategies are applied to different regions of the substrate based on their structural characteristics. Regions with regular structures use standard spectrum analysis, while regions with irregular structures use alternative monitoring approaches, optimizing measurement accuracy for each local area
2Adaptability or versatility
If multiple pressing mechanisms are used to independently press multiple zones of the substrate, then adaptability is improved, but device complexity increases
Solution Approach 1:
The top ring is divided into multiple independent pressing mechanisms (e.g., multiple air bags) that can be controlled separately. Each pressing mechanism corresponds to a specific zone of the substrate, enabling independent adjustment of pressing forces for central, intermediate, and edge zones to accommodate different polishing requirements
Solution Approach 2:
The top ring structure integrates multiple functions: substrate holding, rotation drive, and multi-zone independent pressing control. This universal design allows a single component to perform diverse functions, reducing the need for additional separate mechanisms
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 monitoring of substrate polishing progress and precise detection of the polishing end point by distinguishing between regions with regular and irregular structures, ensuring consistent film-thickness information and improved polishing profiles.
Implementation Method 1
a light source, which is embedded in the polishing tale, illuminates a plurality of measurement points on the surface of the substrate, and a light receiver, which is adjacent to the light source, receives reflected light from the substrate
Implementation Method 2
measuring a spectrum of the reflected light from measurement values of the intensity
Implementation Method 3
the light, directed to the substrate, is reflected off an interface between a medium and the film and an interface between the film and a layer beneath the film. The light waves reflected from these interfaces interfere with each other. The manner of interference between the light waves varies depending on the thickness of the film
Data Source
AI summary
A method of monitoring progress of polishing of a substrate having at least two regions including a first region and a second region with different structures is provided. The method includes: applying light to plural measurement points on the substrate during polishing of the substrate; receiving reflected light from each measurement point; measuring intensity of the reflected light; producing a spectrum of the reflected light from the intensity; classifying the spectrum as spectrum of the reflected light from the first region or as spectrum of the reflected light from the second region based on a shape of the spectrum or the intensity of the reflected light; and monitoring progress of polishing of the substrate based on a temporal change in the spectrum of the reflected light from the first region.