Substrate Temperature Measurement via Gas Channel Pressure Drop
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Solution Overview
Problem
Conventional methods for measuring substrate temperature during processing, such as pyrometry and thermocouples, are impractical in floating wafer reactors due to the need for optical access or mechanical contact, which disrupt the thermal design and gas flow patterns essential for uniform heating.
Innovation Solution
A method utilizing a gas channel with a controlled wall temperature and gas flow to determine substrate temperature by measuring pressure drops, leveraging the thermal interaction between the wall and substrate through a pre-determined relation, allowing for non-contact and non-invasive temperature monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pyrometric temperature measurement is used, then temperature can be measured without mechanical contact, but optical access is required which disturbs the thermal design and gas flow pattern
Solution Approach 1:
The patent introduces gas flow as an intermediary medium to transfer thermal information from the substrate to the measurement system. Instead of direct optical or mechanical contact, the gas flow carries thermal energy that can be measured indirectly through pressure drop, eliminating the need for optical access while maintaining temperature measurement capability
Solution Approach 2:
The patent replaces optical measurement systems with a gas flow-based thermal conduction system. By substituting the optical field with a gas flow field, the system achieves temperature measurement without requiring optical access, thereby preserving the thermal design and gas flow pattern integrity
2Measurement precision
If thermocouples are used for temperature measurement, then temperature can be measured directly, but mechanical contact with the wafer is required which disrupts the gas bearing and flow pattern
Solution Approach 1:
The patent uses gas flow as an intermediary to transfer thermal information without mechanical contact. The gas flow acts as a mediator between the substrate and the measurement system, carrying thermal energy that can be detected through pressure drop changes, thereby avoiding disruption to the gas bearing and flow pattern
Solution Approach 2:
The patent replaces mechanical contact-based thermocouples with a non-contact gas flow-based measurement system. By substituting mechanical contact with gas flow conduction, the system maintains the integrity of the gas bearing while achieving accurate temperature measurement through indirect thermal sensing
3Ease of operation
If the gap between substrate and wall is increased, then easier substrate placement is achieved, but heat conduction efficiency decreases
Solution Approach 1:
The patent makes the gap width a dynamic parameter that can be adjusted during operation. By controlling the gap width to be small (enhancing heat conduction) during the heating phase, and allowing it to be larger during other phases, the system optimizes both heat transfer efficiency and operational ease through dynamic adjustment rather than fixed geometry
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
Enables accurate and continuous monitoring of substrate temperature without disturbing the gas flow or thermal design, improving process control and repeatability in substrate processing.
Implementation Method 1
the at least one channel wall and the substrate have a strong thermal interaction by means of heat conduction through the gas present in the narrow gap that separates them
Implementation Method 2
determining a pressure drop in the gas flow along the gas channel
Data Source
AI summary
The publication discloses a method for determining a temperature of a substrate, comprising: providing a gas channel that is confined by at least one wall having a certain wall temperature; providing a substrate in said gas channel, proximate to the at least one wall, such that a gap exists between a surface of the substrate and the at least one wall; providing a gas flow with a certain mass flow rate through said gas channel, which gas flow extends at least partially through said gap; determining a pressure drop in the gas flow along the gas channel; and deriving from said pressure drop the temperature of said substrate using a pre-determined relation between the pressure drop along the gas channel, the wall temperature and the temperature of the substrate, at said mass flow rate. Also disclosed is a device for implementing the disclosed method.