Wafer-to-Heater Gap Modulation for Temperature Uniformity
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Solution Overview
Problem
Existing wafer preheating methods in semiconductor processing suffer from poor wafer-to-wafer temperature uniformity due to variable residence time in preheat stations, leading to inconsistent deposition quality.
Innovation Solution
Implementing a closed-loop temperature control system that modulates the wafer-to-heater gap using a servo-controlled motor and real-time temperature sensing to maintain a consistent temperature, employing a heated pedestal or movable wafer support for efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed heated pedestal is used for wafer preheating, then the structure is simple and easy to manufacture, but wafer-to-wafer temperature uniformity deteriorates due to variable residence time
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed heated pedestal into a movable one. The pedestal can now adjust its position vertically to modulate the gap distance between the heated surface and the wafer. This dynamic adjustment capability allows the system to compensate for variable residence times and maintain consistent wafer temperatures, thereby improving temperature uniformity without requiring complex multi-component systems
Solution Approach 2:
The patent implements parameter changes by varying the gap distance parameter between the heated pedestal and the wafer. By controlling this geometric parameter dynamically, the heat transfer rate is adjusted in real-time to maintain target wafer temperatures despite variations in residence time. This single parameter control approach achieves improved temperature uniformity while avoiding excessive system complexity
2Temperature
If wafer residence time in preheat station is extended, then wafer temperature increases, but temperature consistency across different wafers deteriorates
Solution Approach 1:
The patent applies feedback control by implementing a closed-loop system that continuously monitors wafer temperature and adjusts the pedestal-gap distance accordingly. Temperature sensors provide real-time feedback to the control system, which then modulates the gap to maintain the desired temperature setpoint. This feedback mechanism decouples temperature control from residence time, ensuring consistent temperatures regardless of when wafers are processed
Solution Approach 2:
The dynamic gap modulation capability allows the system to adapt in real-time to each wafer's heating requirements. Rather than relying on fixed residence times, the system dynamically adjusts the heat transfer rate by changing the gap distance, enabling precise temperature control that maintains consistency across variable processing times
3Measurement precision
If the gap between wafer and heater is kept constant, then the control system is simple, but temperature control precision deteriorates under varying conditions
Solution Approach 1:
The patent implements dynamic gap modulation where the distance between the heated pedestal and wafer is continuously adjusted based on real-time temperature measurements. This dynamic control mechanism enables precise temperature regulation by modulating the heat transfer rate, achieving high temperature control precision while maintaining relatively simple system architecture through single-degree-of-freedom motion 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 ensures precise control of wafer temperature, improving uniformity and consistency across wafers, reducing thermal stress and enhancing deposition quality by decoupling temperature from residence time.
Implementation Method 1
a heated pedestal supplies the heat
Implementation Method 2
a servo controlled linear motor for moving the pedestal or wafer support
Data Source
AI summary
Methods and apparatuses that decouple wafer temperature from pre-heat station residence time, thereby improving wafer-to-wafer temperature uniformity, are provided. The methods involve maintaining a desired temperature by varying the distance between the wafer and a heater. In certain embodiments, the methods involve rapidly approaching a predetermined initial distance and then obtaining and maintaining a desired final temperature using closed loop temperature control. In certain embodiments, a heated pedestal supplies the heat. The wafer-pedestal gap may be modulated may be varied by moving the heated pedestal and/or moving the wafer, e.g., via a movable wafer support. Also in certain embodiments, the closed loop control system includes a real time wafer temperature sensor and a servo controlled linear motor for moving the pedestal or wafer support.