Thermal Chamber Zone Offset Tuning for Wafer Temperature Uniformity
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Solution Overview
Problem
Existing thermal processing systems face challenges in maintaining uniform temperature during rapid thermal processing of semiconductor wafers due to variations in temperature sensor measurements and differences in sensor positions, leading to inaccuracies in temperature control.
Innovation Solution
A method and apparatus that simulate and adjust lamp zone offset values to determine processing values, allowing for independent control of lamp power on a zone-by-zone basis to achieve predetermined temperature goals, thereby improving process uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical pyrometry is used to measure temperature in RTP systems, then temperature measurement capability is provided, but variations between individual temperature sensors and differences in positions of the individual temperature sensors with respect to a particular substrate in the chamber affect the accuracy of the temperature measurements
Solution Approach 1:
The patent applies parameter changes by introducing offset values that adjust the relationship between measured temperature and actual substrate temperature. The system determines offset values for different lamp zones and temperature sensors, then applies these offsets during processing to compensate for sensor variations and positioning differences, thereby improving measurement accuracy and consistency
Solution Approach 2:
The patent creates a virtual model of the thermal processing chamber that replicates the physical system's behavior. This virtual chamber includes virtual temperature sensors and lamp zones that mirror the physical configuration, allowing the system to simulate and determine offset values that can be applied to the actual system, effectively copying the physical system's characteristics into a controllable virtual environment
2Temperature
If lamps are divided into zones and controlled together to produce a desired temperature in the chamber, then temperature control capability is provided, but process uniformity across the substrate is difficult to achieve due to temperature variations
Solution Approach 1:
The patent segments the lamp control system into multiple independently controllable zones, each with its own offset value. Instead of controlling all lamps uniformly, the system divides the lamphead into radial zones and applies zone-specific offset adjustments, allowing independent optimization of temperature distribution across different regions of the substrate to achieve better process uniformity
Solution Approach 2:
The patent implements local quality by applying different offset values to different lamp zones based on their specific thermal characteristics and positions relative to the substrate. Each zone is optimized locally with its own offset parameter, allowing the system to account for radial temperature variations and achieve more uniform processing across the entire substrate surface
3Power
If lamp power is adjusted to achieve desired temperature, then heating capability is provided, but temperature deviations occur due to sensor variations and positioning differences
Solution Approach 1:
The patent implements feedback by continuously monitoring temperatures with multiple sensors, comparing measured temperatures against target values, and adjusting lamp power accordingly. The system uses offset values derived from sensor measurements to create feedback loops that compensate for sensor variations, ensuring that lamp power adjustments are based on accurate temperature information and resulting in more precise temperature control
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 enhances temperature uniformity across the substrate by precisely adjusting lamp power distribution, reducing temperature deviations and improving processing consistency, as demonstrated by reduced standard deviation and edge slope variations.
Implementation Method 1
heat energy radiates from radiation sources into the process chamber and to a semiconductor substrate in the processing chamber
Implementation Method 2
optical pyrometry is used to measure temperature in RTP systems. One or more pyrometers measure emitted radiation intensity from an object and perform an appropriate calculation to obtain a temperature
Data Source
AI summary
A method for controlling temperature in a thermal processing chamber includes determining temperature sensitivity profiles of one or more heating elements or zones for a substrate based on measurements of the substrate. The method also includes selecting a temperature offset value for each of the one or more heating elements or zones. The method also includes simulating the adjustment of each of the one or more zone offset values to a respective final adjusting value that achieves a predetermined goal. The method further includes adjusting the temperature offset values for each of the one or more heating elements to the respective final adjusted values.