Flash Lamp Annealing Temperature Measurement for Multilayer Wafers
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Solution Overview
Problem
Recent advancements in semiconductor technology, particularly the stacking of multiple thin films, complicate accurate temperature measurement during flash lamp annealing due to changes in apparent emissivity, leading to potential inaccuracies in process control and yield deterioration.
Innovation Solution
A heat treatment method and apparatus that calculate and set the emissivity of a substrate based on film information, substrate information, and radiation thermometer installation angle, allowing for accurate temperature measurement using a weighted average efficiency, especially for substrates with multiple thin film layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radiation thermometer is used to measure temperature of a semiconductor wafer with multilayer thin films, then temperature measurement is enabled, but measurement precision deteriorates due to changes in apparent emissivity caused by multiple thin film layers
Solution Approach 1:
The invention changes the parameter of emissivity from a fixed value to a dynamically calculated value based on film information (type, thickness, refractive index) and measurement conditions (wavelength, angle). This allows the radiation thermometer to adapt to different multilayer film configurations and achieve accurate temperature measurement despite varying emissivity characteristics.
Solution Approach 2:
The invention implements a feedback mechanism where the measured temperature and film information are used to calculate the apparent emissivity, which then feeds back to correct the temperature measurement. This closed-loop approach compensates for emissivity variations caused by multilayer thin films and improves measurement precision.
2Measurement precision
If the installation angle of the radiation thermometer is decreased to measure substrates with thin films, then measurement is possible, but measurement precision deteriorates when multiple thin films are stacked due to apparent emissivity changes
Solution Approach 1:
The invention incorporates the installation angle as a variable parameter in the emissivity calculation model. By updating the optical path and interference conditions based on the measurement angle, the system accurately determines apparent emissivity for oblique measurements on multilayer films, maintaining precision without requiring normal incidence.
3Ease of operation
If conventional emissivity of silicon is used for temperature measurement, then measurement is simplified, but measurement precision deteriorates for substrates with multiple thin film layers
Solution Approach 1:
The invention enables the measurement system to self-determine the appropriate emissivity value by automatically calculating it from the provided film information and measurement conditions. This eliminates the need for manual emissivity selection or calibration, maintaining ease of operation while achieving high precision for multilayer film substrates.
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 temperature measurement of substrates with multiple thin film layers, ensuring correct process execution and improved yield by accounting for changes in emissivity.
Implementation Method 1
irradiating a thin-plated precision electronic substrate (hereinafter referred to as simply 'substrate') such as a semiconductor wafer with a flash of light to heat the substrate
Implementation Method 2
temperature of a semiconductor wafer to be typically measured by a non-contact radiation thermometer
Data Source
AI summary
Film information about a thin film formed on the front surface of a semiconductor wafer, substrate information about the semiconductor wafer, and an installation angle of an upper radiation thermometer are set and input. Emissivity of the front surface of the semiconductor wafer formed with a multilayer film is calculated based on the various kinds of information. Further, a weighted average efficiency of the emissivity of the front surface of the semiconductor wafer is determined based on a sensitivity distribution of the upper radiation thermometer. Front surface temperature of the semiconductor wafer at the time of heat treatment is measured using the determined weighted average efficiency of the emissivity. The emissivity is determined based on the film information and the like, so that the front surface temperature of the semiconductor wafer can be accurately measured even when thin films are formed in multiple layers.