In-situ Wafer Temperature Control via Direct Thermal Monitoring
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Solution Overview
Problem
Conventional ion implantation systems rely on indirect temperature measurement of workpiece supports, leading to temperature errors during processing due to decoupling between the support and workpiece temperatures, especially during high-temperature implants where precise control is crucial.
Innovation Solution
A thermal chuck system with direct and non-contact thermal monitoring devices, such as thermocouples and pyrometers, is used to accurately measure and control the workpiece temperature by directly contacting or sensing the workpiece's surface, allowing for precise heating and cooling control through redundant temperature measurements and dynamic adjustment of heater output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If indirect temperature measurement of the workpiece support is used, then the measurement system is simple, but the temperature control accuracy deteriorates due to decoupling between support and workpiece temperatures
Solution Approach 1:
The patent introduces a thermal monitoring device as an intermediary element that directly contacts the workpiece to measure its temperature, rather than measuring the support temperature indirectly. This mediator (thermal monitoring device) bridges the gap between the support and the workpiece, providing accurate workpiece temperature data while maintaining system simplicity through direct measurement.
Solution Approach 2:
The patent replaces the indirect mechanical measurement approach (measuring support temperature) with a direct thermal sensing approach (measuring workpiece temperature through thermal contact or non-contact sensing). This substitution eliminates the decoupling error between support and workpiece temperatures while using well-established thermal measurement technologies.
2Manufacturing precision
If direct workpiece temperature measurement is implemented, then temperature control accuracy improves, but the device complexity increases due to additional monitoring equipment
Solution Approach 1:
The patent implements a feedback control system where the thermal monitoring device continuously measures workpiece temperature and feeds this information back to the controller, which adjusts the heater power accordingly. This closed-loop feedback mechanism ensures precise temperature control during implantation processes while integrating seamlessly with existing thermal chuck systems.
Solution Approach 2:
The thermal monitoring device serves multiple functions: it measures workpiece temperature, provides feedback for control, and can detect temperature uniformity across the workpiece surface. This multi-functionality justifies the added complexity by delivering comprehensive temperature management capabilities that improve overall process precision.
3Reliability
If redundant temperature measurements are used, then measurement reliability improves, but the device complexity and cost increase
Solution Approach 1:
The patent incorporates redundant thermal monitoring devices as a form of prior cushioning against measurement failure or error. By having multiple independent measurement channels, the system is protected against single-point failures, ensuring continuous reliable temperature data for critical implantation processes without requiring complex active redundancy management.
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 enables precise and accurate temperature control of the workpiece, independent of the thermal chuck's temperature, ensuring consistent implantation conditions and improving process accuracy and efficiency across various temperature regimes.
Implementation Method 1
A thermal monitoring device is configured to determine a temperature of a surface of the workpiece when the workpiece resides on the clamping surface
Implementation Method 2
a pyrometer...configured to sense the temperature of the workpiece without contacting the workpiece
Implementation Method 3
one or more heaters configured to selectively heat the clamping surface, thereby selectively heating the workpiece
Implementation Method 4
the chilled chuck is cooled to a chilled temperature, thereby cooling the workpiece. Cooling the chilled chuck provides for a removal of thermal energy imparted into the workpiece
Data Source
AI summary
A thermal chuck selectively retains a workpiece on a clamping surface. The thermal chuck has one or more heaters to selectively heat the clamping surface and the workpiece. A thermal monitoring device determines a temperature of a surface of the workpiece when the workpiece resides on the clamping surface, defining one or more measured temperatures. A controller selectively energizes the one or more heaters based on the one or more measured temperatures. The thermal monitoring device may be one or more of a thermocouple or RTD in selective contact with the surface of the workpiece and an emissivity sensor or pyrometer not in contact with the surface. The thermal chuck can be part of an ion implantation system configured to implant ions into the workpiece. The controller can be further configured to control the heaters based on the measured temperatures.