Substrate Heater Control for Critical Dimension Uniformity
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Solution Overview
Problem
In substrate processing, achieving uniform critical dimension control is challenging due to temperature variations near the boundaries of divided regions on the placement surface, leading to inaccuracies in controlling the critical dimension, especially at the outer edge and boundary areas.
Innovation Solution
A substrate processing apparatus with a placing table divided into regions, each equipped with a heater, uses a calculation unit and heater controller to adjust temperatures based on a prediction model that considers the influence of adjacent regions, ensuring the critical dimension at measurement points meets predetermined conditions by calculating target temperatures and controlling heaters to reach those temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the placement surface is divided into multiple regions with heaters for temperature control, then the temperature uniformity is improved, but the temperature control accuracy at boundary regions deteriorates due to thermal influence from adjacent regions
Solution Approach 1:
The invention changes the control parameters by introducing a prediction model that calculates the thermal influence from adjacent regions. The calculation unit computes the actual temperature at measurement points by combining the set temperatures of multiple heaters with their respective influence coefficients, then uses this predicted temperature to determine corrected heater set values that compensate for boundary thermal interference.
Solution Approach 2:
The invention implements a feedback mechanism where the actual temperature distribution (predicted through the calculation unit using measurement data) is fed back to adjust the heater control. The prediction model uses measured critical dimension data and temperature data to calculate influence coefficients, which are then used to adjust heater set values in subsequent processing cycles, continuously improving temperature control accuracy.
2Adaptability or versatility
If the heater temperature in each divided region is controlled independently, then the temperature adjustment flexibility is improved, but the critical dimension uniformity deteriorates due to unaccounted thermal influence from adjacent heaters
Solution Approach 1:
The invention transforms the independent heater control parameters into a coordinated system by introducing influence coefficients that quantify the thermal interaction between adjacent heaters. The calculation unit computes corrected set values for each heater by considering both its own set temperature and the temperatures of neighboring heaters, weighted by their respective influence coefficients, thereby maintaining flexibility while achieving uniformity.
Solution Approach 2:
The invention introduces a prediction model and calculation unit as intermediaries between the independent heater controls and the substrate temperature distribution. This intermediary system calculates the cumulative thermal influence from all heaters on each measurement point, enabling the independent heater controls to work together harmoniously to achieve uniform critical dimension across the substrate.
3Manufacturing precision
If a prediction model considering adjacent region influence is used, then the critical dimension control accuracy is improved, but the device complexity increases due to additional calculation and control mechanisms
Solution Approach 1:
The invention replaces complex physical temperature measurement and adjustment mechanisms with a computational prediction model. Instead of adding physical sensors and mechanical adjustment devices to each heater zone, the system uses software-based calculations to predict temperature distribution and compute corrected set values, significantly reducing hardware complexity while maintaining high control accuracy.
Solution Approach 2:
The invention creates a virtual model (prediction model) that replicates the thermal behavior of the physical heating system. The calculation unit computes a virtual temperature distribution based on heater set values and influence coefficients, then uses this virtual model to determine optimal control parameters without requiring complex physical measurement and adjustment infrastructure.
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 the critical dimension across the substrate, minimizing errors and ensuring uniformity by accounting for the temperature influence of adjacent regions, thereby improving the accuracy of substrate processing.
Implementation Method 1
a heater is provided for each divided region. Then, the temperature of each divided region is adjusted
Data Source
AI summary
A substrate processing apparatus includes: a placing table having a placement surface and provided with a heater in each divided region obtained by dividing the placement surface; a calculation unit that calculates a target temperature of the heater in each divided region in which a critical dimension at a predetermined measurement point satisfies a predetermined condition, using a prediction model that predicts the critical dimension of the measurement point by using a temperature of the heater in each divided region as a parameter and taking into consideration an influence of a temperature of a heater in a divided region other than a divided region including the measurement point in accordance with a distance between the measurement point and the other divided region; and a heater controller that controls the heater in each divided region to reach the target temperature when the substrate processing is performed on the substrate.