Wafer Temperature Control Using Response Waveform Matrix
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Solution Overview
Problem
Conventional temperature control methods for hot plates in semiconductor wafer processing systems fail to maintain uniform temperature across the wafer surface, leading to temperature variations during heat processes, especially during transient times, due to differences in heat release at the wafer's central and peripheral portions and individual variations among heat processing units.
Innovation Solution
A temperature control method that involves measuring stepped response waveforms at multiple points, composing pulsed and triangular response waveforms, and using these to acquire a matrix showing the relation between target temperatures and substrate temperatures, allowing for precise adjustment of target temperatures to achieve uniformity by calculating adjustment information based on temperature distribution data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the temperature of the hot plate is controlled to be uniform, then the temperature uniformity of the hot plate is improved, but the temperature uniformity of the substrate cannot be maintained due to heat release differences and transient time variations
Solution Approach 1:
The patent applies local quality by dividing the substrate into multiple measurement regions and assigning different target temperatures to each region based on its specific heat release characteristics. The central portion, peripheral portion, and other regions are treated differently with customized temperature adjustments to compensate for local heat release variations, thereby achieving uniform substrate temperature across the entire surface.
Solution Approach 2:
The patent changes the temperature parameter dynamically by calculating adjustment values for target temperatures based on measured temperature distributions and pre-acquired response waveforms. The control system modifies target temperatures for different regions and time points to account for transient time effects and individual differences among heat processing units, transforming a static uniform temperature control into a dynamic adaptive control system.
2Stability of the object's composition
If conventional temperature control is used, then the hot plate temperature can be maintained, but temperature variations occur on the substrate surface during heat processes
Solution Approach 1:
The patent implements feedback control by measuring the actual temperature distribution on the substrate surface during heat processing and using this information to calculate adjustment values for target temperatures. The system continuously monitors temperature variations and adjusts control parameters accordingly, creating a closed-loop control system that compensates for temperature deviations caused by heat release differences and transient effects.
Solution Approach 2:
The patent applies preliminary action by pre-acquiring response waveforms that characterize the thermal behavior of the substrate under different target temperature conditions. These pre-measured response waveforms are stored and used to predict and compensate for temperature variations before they occur, allowing the system to proactively adjust target temperatures rather than merely reacting to temperature deviations.
3Productivity
If individual heat processing units are used, then processing capacity is improved, but temperature variations increase due to individual differences among units
Solution Approach 1:
The patent addresses individual differences among heat processing units by acquiring response waveforms for each unit and calculating unit-specific adjustment values for target temperatures. Each heat processing unit is characterized individually through measurement, and the control system applies customized temperature adjustment parameters to compensate for unit-specific variations, thereby maintaining temperature consistency across multiple processing units while preserving processing capacity.
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 method effectively reduces temperature variations across the wafer surface, ensuring a uniform temperature state by adjusting target temperatures in real-time, thereby improving the precision and consistency of heat processes in semiconductor wafer processing.
Implementation Method 1
a heater (127) built in the hot plate (121)
Implementation Method 2
a temperature sensor built in the hot plate to control the temperature to be a target temperature
Implementation Method 3
the semiconductor wafer tends to release heat more at the peripheral portion than at the central portion on the surface
Data Source
AI summary
A temperature control method for a heat process on a resist film on a substrate includes first and second steps. The first step includes measuring a stepped response waveform of measured temperatures of a substrate at measurement points while changing stepwise each target temperature, then using this result to compose a pulsed response waveform with respect to a change of a pulsed target temperature, then using this result to compose a triangular response waveform with respect to a change of a triangular target temperature, and then using this result to acquire a matrix as relation information showing a relation between the target temperatures and temperatures of the substrate at measurement points. The second step includes acquiring temperature distribution information by use of measured temperatures of the substrate placed on the hot plate, measured at measurement points before adjustment of the target temperatures, and then calculating adjustment information by use of the relation information acquired in the first step and the temperature distribution information, thereby determining adjustment information.