Chromatic Confocal Wafer Stress Scanning With Temperature Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wafer stress measurement methods in semiconductor manufacturing are ex-situ, which disrupt the vacuum environment, causing contamination and slowing down production, and lack precision due to sensitivity to surface optical properties and low resolution.
Innovation Solution
A system using a chromatic confocal sensor and temperature sensor, integrated with a robot arm, measures wafer stress in-situ by compensating for temperature variations and vibrations, enabling precise bow and stress profile generation during thin film deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ex-situ measurement methods are used to measure wafer stress, then measurement can be performed, but the vacuum environment is disrupted causing contamination and production slowdown
Solution Approach 1:
A transparent window is introduced as an intermediary component that allows optical measurement signals to pass through while maintaining the vacuum seal. The window enables the chromatic confocal sensor to measure wafer stress without breaking vacuum, thus preventing contamination and maintaining production continuity
Solution Approach 2:
The patent replaces mechanical contact-based ex-situ measurement systems with an optical-based in-situ measurement system. The chromatic confocal sensor uses light to measure wafer bow and stress without physical contact, eliminating the need to break vacuum for measurement
2Measurement precision
If ex-situ measurement methods are used, then wafer stress can be measured, but the measurement process is slow and disrupts the manufacturing flow
Solution Approach 1:
The measurement system is pre-configured and ready to operate within the vacuum chamber. The chromatic confocal sensor and illumination system are positioned in advance, allowing immediate measurement without interrupting the deposition process or requiring wafer removal
Solution Approach 2:
The measurement process continues uninterrupted during wafer handling and between deposition steps. The system performs real-time stress measurements without stopping the manufacturing flow, maintaining continuous productive action
3Measurement precision
If traditional optical measurement methods are used, then wafer bow can be measured, but the measurements are sensitive to surface optical parameters and angles of incidence
Solution Approach 1:
The patent replaces traditional optical interferometry methods with chromatic confocal sensing. This optical-to-optical substitution uses wavelength-dependent focus rather than interference patterns, eliminating sensitivity to surface reflectivity, optical parameters, and angle variations
Solution Approach 2:
The measurement approach changes from measuring interference patterns to measuring the wavelength of reflected light at different focal positions. This parameter change from phase measurement to wavelength measurement makes the system insensitive to surface optical properties
4Speed
If fast profiling systems are used, then measurement speed is improved, but lateral resolution is low
Solution Approach 1:
The measurement is segmented into multiple sequential one-dimensional scans across the wafer surface. By combining multiple high-resolution linear measurements, the system achieves both fast data acquisition and high lateral resolution without requiring a complex two-dimensional sensor array
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, real-time stress measurement without disrupting the vacuum environment, improving production efficiency and yield by providing precise stress profiles for process control.
Implementation Method 1
a chromatic confocal sensor configured to measure a wavelength of light reflected by the workpiece as the robot arm moves the workpiece along the movement path
Implementation Method 2
a temperature sensor configured to measure a surface temperature of the workpiece as the robot arm moves the workpiece along the movement path
Implementation Method 3
The processor may be further configured to filter the first scanning signal to produce a first filtered signal that compensates for temperature variations of the workpiece according to the first temperature signal
Data Source
AI summary
A system includes a process chamber, a transport chamber connected to the process chamber, a robot arm that supports a workpiece, a chromatic confocal sensor, a temperature sensor, and a processor. The robot arm is configured to move the workpiece along a movement path between the process chamber and the transport chamber, and as the robot arm moves the workpiece along the movement path, the chromatic confocal sensor is configured to measure a wavelength of light reflected by the workpiece and the temperature sensor is configured to measure a surface temperature of the workpiece. The processor is configured to filter a first scanning signal received from the chromatic confocal sensor to produce a first filtered signal that compensates for temperature variations of the workpiece according to a first temperature signal received from the temperature sensor, and generate a first bow profile of the workpiece based on the first filtered signal.