CMP Film-Thickness Measurement With Synchronized Notch Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor manufacturing, achieving accurate film-thickness distribution and notch portion detection on substrates during chemical mechanical polishing (CMP) is challenging due to variations in film thickness and difficulty in determining corresponding positions, leading to suboptimal surface planarization and interconnect formation.
Innovation Solution
A film-thickness measuring method and polishing apparatus that synchronizes the position of a film-thickness measuring device with the polishing head, using oscillating and rotating motors to control the device's position relative to the substrate, allowing for precise measurement and correction of film thickness variations, including detecting notch portions by tracing specific paths on the substrate's periphery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a film-thickness sensor traverses the substrate to measure film thickness at multiple measurement points, then film-thickness distribution can be measured, but measurement accuracy deteriorates because measurement points depend on rotation speed, installation position, and polishing time
Solution Approach 1:
The patent uses a camera to capture an image of the substrate surface, creating a visual copy of the film thickness distribution. This optical copying method replaces the traditional physical sensor traversal, allowing measurement of film thickness at multiple points simultaneously without the accuracy problems associated with sensor position dependency on rotation speed and installation position.
Solution Approach 2:
The patent replaces the mechanical film-thickness sensor traversal system with an optical imaging system. Instead of physically moving a sensor across the rotating substrate, a camera captures the entire substrate surface image, eliminating the mechanical complexity and position dependency issues of the sensor traversal method.
2Measurement precision
If a film-thickness measuring device is installed separately from the polishing apparatus, then film-thickness distribution can be measured before polishing, but it becomes difficult to determine positions on the substrate corresponding to measured values during polishing
Solution Approach 1:
The patent merges the film-thickness measuring function with the polishing apparatus by integrating a camera into the polishing system. The camera is positioned to capture substrate images during polishing, and the obtained images are stored together with polishing condition information, maintaining position correspondence between measured film thickness values and substrate locations throughout the polishing process.
3Manufacturing precision
If the substrate is polished to eliminate film thickness variation, then surface planarization is achieved, but measurement accuracy deteriorates without accurate position determination of notch portions
Solution Approach 1:
The patent utilizes the visual appearance changes of the substrate surface, including notch portions, captured by the camera. By analyzing the image data obtained during polishing, the system can identify and locate notch portions based on their distinct visual characteristics in the captured images, maintaining accurate position detection throughout the polishing process.
Data Source
AI summary
A polishing method capable of accurately determining a polishing end point of a substrate is disclosed. The method is a film-thickness measuring method for a substrate W using a film-thickness measuring device, at least a part of which being mounted in a polishing table configured to support the polishing pad. The method includes measuring film thicknesses of the substrate W, while rotating the substrate W on a polishing surface of the polishing pad by a polishing head and controlling a position of the film-thickness measuring device relative to the polishing head.