Semiconductor Chamber Temperature Calibration via Layer Emissivity
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Solution Overview
Problem
Existing temperature control systems in semiconductor processing chambers face inaccuracies due to thermocouple drift, varying heat lamp power, reflective surface degradation, and emissivity changes, leading to non-uniform substrate temperature control, which is often calibrated using costly and time-consuming methods like thickness monitor wafers or visual interpretation of color variations.
Innovation Solution
A method and apparatus that utilize cyclical properties of deposited layers, such as emissivity or color, to measure and adjust the temperature control system by determining the cycle time period of these properties, allowing for precise calibration without the need for thickness monitor wafers or boron-implanted wafers, using sensors to measure and adjust the heating apparatus based on empirical models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thickness monitor wafers or boron-implanted wafers are used for calibration, then measurement precision is improved, but loss of time and loss of substance increase
Solution Approach 1:
The patent replaces physical wafer-based calibration methods with an optical detection system. A pyrometer measures the thermal radiation emitted by the susceptor, and a camera captures images of the susceptor at different temperatures. The system processes these images to determine temperature-based color variations, eliminating the need for thickness monitor wafers or boron-implanted wafers and their associated time-consuming manual measurement and analysis steps
Solution Approach 2:
The patent creates a visual copy of the susceptor's thermal state through camera imaging. Instead of using physical test wafers, the system captures optical images that represent the temperature distribution, then analyzes these image copies to extract temperature information through color variation analysis, providing a non-contact calibration method
2Speed
If pyrometers are used for temperature measurement, then speed of measurement is improved, but measurement precision deteriorates due to interference from other light sources
Solution Approach 1:
The patent introduces an intermediary filtering mechanism through image processing algorithms. The camera captures images that may contain interference from heating lamps and other light sources, then the system processes these images to isolate the thermal radiation signal from the susceptor, effectively filtering out unwanted light interference while maintaining the non-contact measurement advantage
Solution Approach 2:
The patent focuses the measurement on specific local characteristics of the susceptor - the color variations at different temperatures and positions. By analyzing localized color changes in specific regions of the susceptor rather than relying on total radiation measurement, the system can distinguish thermal signal from interference light more effectively
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 quick and accurate calibration of temperature control systems, reducing reactor downtime and improving substrate throughput by automatically adjusting for temperature sensor inaccuracies and other factors affecting temperature control, thereby enhancing device yield and reducing the risk of process deviations.
Implementation Method 1
A heating apparatus, a temperature sensor, and a temperature control system are provided. The heating apparatus is configured to heat a processing chamber.
Implementation Method 2
The temperature sensors typically comprise thermocouples mounted around and below the substrate, or optical pyrometers that allow temperature to be determined by measuring the substrate's thermal radiation.
Implementation Method 3
The temperature control system is configured to control the heating apparatus based on the signal from the temperature sensor.
Implementation Method 4
A thickness of a layer of material in the processing chamber is varied. While varying the layer thickness, a variation of a property of the layer is measured, the property having a cyclical variation as a thickness of the layer varies.
Data Source
AI summary
Methods and systems for calibrating a temperature control system in a vapor deposition chamber. A temperature sensor senses temperature within a semiconductor processing chamber and generates an output signal. A temperature control system controls a chamber temperature by controlling a heating apparatus based on the output signal. A method includes instructing the control system to target a setpoint temperature, and depositing a layer of material onto a surface in the chamber by a vapor deposition process. A variation of a property of the layer is measured while depositing the layer, the property known to vary cyclically as a thickness of the layer increases. The measured property is allowed to vary cyclically for one or more cycles. If there is a difference between a time period of one or more of the cycles and an expected time period associated with the setpoint temperature, the temperature control system is adjusted based on the difference.