CMP Sensor Data Filtering for Accurate Wafer Polishing Measurement
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Solution Overview
Problem
In chemical-mechanical polishing processes, the variation in the position of the substrate relative to the sensor during polishing leads to inaccurate measurement of physical quantities such as film thickness, temperature, and vibration due to the oscillation of the polishing head and substrate, resulting in noise data.
Innovation Solution
A method and apparatus that determine effective data points by counting measurement data points within a defined search area and time range, using a sensor installed in the polishing table to accurately measure physical quantities, and calculate a representative value based on these points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the polishing head and substrate are oscillated during polishing, then the polishing uniformity is improved, but the sensor may be located outside the substrate in the predetermined measurement region, resulting in noise data
Solution Approach 1:
The patent applies preliminary action by pre-defining a search area larger than the substrate before oscillation occurs. This search area is established in advance to anticipate the substrate's movement during oscillation, ensuring that measurement data collection is prepared to capture valid data points even as the substrate moves out of the original predetermined measurement region.
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the data selection process based on substrate oscillation. Instead of using a fixed measurement region, the system adapts by searching within an expanded area and selecting data points based on their validity during oscillation, making the measurement system responsive to the dynamic movement of the substrate.
2Quantity of substance
If multiple measurement data points are collected during one revolution, then the measurement coverage is improved, but the data includes noise from measurements taken when the sensor is outside the substrate
Solution Approach 1:
The patent applies taking out by extracting only the valid measurement data points from the collected data set. The system identifies and separates effective data points (where the sensor was over the substrate) from noise data points (where the sensor was outside the substrate), keeping only the reliable measurements for determining the representative value.
Solution Approach 2:
The patent implements local quality by applying different evaluation criteria to different data points based on their validity. Instead of treating all measurement data points equally, the system assigns different weights or validity statuses to data points depending on whether they were collected when the sensor was positioned over the substrate or outside it, thereby improving overall data reliability.
Data Source
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AI summary
The present invention relates to a polishing method of polishing a substrate, such as a wafer or a panel. The polishing method includes: rotating a polishing pad (polishing tool) (1) having a polishing surface (1a); pressing a substrate (W) against the polishing surface (1a) to polish the substrate (W); during polishing of the substrate, determining whether each of multiple measurement data points measured by a sensor (30) is an effective data point; and determining a representative measurement value of physical quantity based on a measurement value of a measurement data point that has been determined to be the effective data point each time the polishing table (3) makes one revolution. Determining whether each of the multiple measurement data points is the effective data point comprises counting the number of measurement data points within a search area and determining that a determination-target measurement data point is the effective data point when the number of measurement data points within the search area is equal to or more than a threshold value.