Wafer Emissivity Measurement for Thermal Process Control
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Solution Overview
Problem
Existing semiconductor device manufacturing methods struggle to accurately control film thickness and impurity concentration distribution due to changes in manufacturing apparatus conditions, leading to variations in semiconductor device production and reduced yield.
Innovation Solution
The method involves measuring the emissivity of a wafer, calculating the fluctuation rate of a physical quantity associated with thermal energy, and adjusting processing time based on this calculation to maintain desired film thickness or impurity concentration, even in changing apparatus conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing apparatus control methods are used, then the apparatus operation is simple, but the film thickness control precision deteriorates due to apparatus condition changes
Solution Approach 1:
The patent implements a feedback mechanism where the measured physical quantity (related to film thickness) is compared with the target value, and the processing time is adjusted based on the deviation. The process controller continuously monitors the physical quantity during thermal processing and modifies the processing time to compensate for apparatus condition changes, thereby maintaining precise film thickness control despite variations in apparatus performance.
Solution Approach 2:
The patent replaces direct mechanical measurement of film thickness with an indirect measurement approach using optical or other non-contact methods to measure a physical quantity that correlates with film thickness. This substitution allows for real-time monitoring without disrupting the thermal processing mechanism, enabling precise control while maintaining apparatus simplicity.
2Manufacturing precision
If processing time is extended to ensure sufficient film formation, then film thickness uniformity improves, but production productivity deteriorates
Solution Approach 1:
The patent makes the processing time dynamic rather than fixed. The process controller adjusts the processing time in real-time based on the measured physical quantity and the calculated deviation from the target value. This dynamic adjustment allows the system to achieve uniform film thickness with optimized processing times, preventing both under-processing and unnecessary over-processing that would reduce productivity.
Solution Approach 2:
The patent changes the processing time parameter based on measured conditions. By calculating the deviation between the measured physical quantity and the target value, and applying a proportional adjustment to the processing time, the system adapts the thermal processing duration to actual apparatus conditions, ensuring uniform film formation while minimizing cycle time.
3Manufacturing precision
If multiple measurement points are used to ensure comprehensive quality control, then manufacturing precision improves, but measurement complexity and time increase
Solution Approach 1:
The patent extracts and monitors a single key physical quantity that serves as an indicator of film formation status throughout the wafer. Instead of measuring multiple parameters or taking multiple measurements, the system focuses on one critical physical quantity that correlates with film thickness, enabling comprehensive quality control with minimal measurement time and complexity.
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
This approach allows for precise control of film thickness and impurity concentration distribution, reducing variations and improving production yield by continuously adapting to changes in manufacturing apparatus conditions.
Implementation Method 1
the latter, pyrometer, performs better than the thermo couple in measuring the wafer temperature. However, the pyrometer does not precisely measure the wafer temperature itself, either. The pyrometer converts incident heat emission to temperature.
Data Source
AI summary
In the semiconductor device manufacturing method of the present invention, first, the emissivity of a wafer placed in a chamber is measured. Then, the fluctuation rate of a wafer physical quantity that fluctuates in association with the given thermal energy is calculated based on an estimate expression, which are obtained in advance, presenting the relationship between the thermal energy quantity emitted from the heat source for heating the wafer, wafer emissivity and the wafer physical quantity fluctuation rate and on the measured emissivity. Subsequently, the processing time for the physical quantity to be a specific value is calculated based on the calculated fluctuation rate. Then, the thermal process is conducted for the calculated processing time.