Wafer Polishing End Point Detection Using Color Image Sensor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for detecting the end point of etching and polishing processes on semiconductor wafers are not precise and efficient in real-time, leading to potential damage to underlying layers and reduced production yield due to surface roughness and noise interference.
Innovation Solution
A wafer polishing apparatus equipped with a polishing tape, a color image sensor, and a controller that detects color changes on the polishing tape to determine the end point of the polishing process, reducing logical operation processing work and enhancing detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If emission spectroscopy analysis is used to detect etching end point, then detection can be performed, but real-time detection is difficult and over-etching damage occurs to underlying layers
Solution Approach 1:
The patent replaces the conventional emission spectroscopy analysis with a visual detection system using a camera to capture images of the wafer surface. This substitution enables real-time detection by directly observing color changes on the wafer surface during etching, eliminating the time delay and over-etching damage associated with conventional spectroscopic methods that cannot detect end points in real-time.
Solution Approach 2:
The patent utilizes color changes on the wafer surface as an indicator of etching end point. By capturing images with a camera and analyzing color variations, the system achieves real-time detection of when etching should stop, preventing over-etching damage while maintaining detection precision.
2Productivity
If conventional polishing methods are used, then polishing can be performed, but surface roughness and protrusions are generated reducing production yield
Solution Approach 1:
The patent implements a feedback mechanism by continuously capturing images of the wafer surface during polishing and analyzing color changes to detect when polishing end point is reached. This real-time feedback allows the polishing process to stop precisely when the surface is smooth, preventing the generation of protrusions and surface roughness that would reduce production yield.
3Measurement precision
If emission intensity variation is used to determine etching end point, then end point can be detected, but detection sensitivity is reduced in small areas due to noise
Solution Approach 1:
The patent replaces emission intensity measurement with direct visual imaging using a camera. This substitution eliminates noise interference that plagues conventional spectroscopic methods, particularly in small areas, by providing direct optical detection of color changes on the wafer surface without being affected by plasma noise or signal interference.
Solution Approach 2:
The patent uses color changes as a robust indicator for end point detection that is not susceptible to noise interference. By capturing images and analyzing color variations, the system achieves high detection sensitivity even in small areas where conventional emission intensity methods fail due to noise.
4Measurement precision
If refraction lattice is driven by motor for wavelength separation, then spectral analysis can be performed, but adjustment time is long reducing efficiency
Solution Approach 1:
The patent replaces the motor-driven refraction lattice system with a simple camera-based imaging system. This substitution eliminates the need for mechanical adjustment and wavelength separation, allowing immediate capture of color information without time-consuming motor adjustments, thereby significantly reducing loss of time while maintaining detection accuracy.
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 precise and real-time detection of the polishing end point, minimizing damage to underlying layers and improving production efficiency by accurately determining when the polishing is complete.
Implementation Method 1
a color image sensor adjacent to the polishing tape, the color image sensor being adapted to detect a color image of the polishing tape and to output a signal corresponding to the detected color image
Data Source
AI summary
A wafer polishing apparatus includes a polishing tape extending between two guide rollers, a first surface of the polishing tape contacting a surface of a wafer to be polished, a polishing head including a pusher pad, the pusher pad adapted to push the polishing tape against the surface of the wafer to be polished, a color image sensor adjacent to the polishing tape, the color image sensor being adapted to detect a color image of the polishing tape and to output a signal corresponding to the detected color image, and a controller connected to the color image sensor, the controller being adapted to receive the signal output from the color image sensor and to determine when a color of the color image detected by the color image sensor changes, a change in the color image indicating a polishing end point.