Wafer Positioning via Processing Gas Pressure
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Solution Overview
Problem
Accurate positioning and distance control between a semiconductor wafer and processing body in semiconductor processing systems are challenging due to variable reflectivity of wafers with dielectric and conductive films, and mechanical measurements are difficult to implement, especially in complex equipment where contact is not desirable.
Innovation Solution
A method involving the measurement of processing gas pressure within a flow extending through a gap between a processing body and a wafer, allowing for the detection of changes in gap width and wafer alignment, using pressure sensors and vertical position measurements to determine the relative positions and thickness variations without mechanical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical measurements are used to determine distance, then measurement capability is provided, but measurement precision deteriorates due to variable reflectivity of wafer films
Solution Approach 1:
The patent replaces optical measurement systems with a pneumatic measurement system. Instead of using light to measure the distance between the wafer and processing body, the invention uses processing gas pressure as a mechanical proxy. The pressure of the processing gas in the gap between the wafer and processing body directly indicates the gap width, eliminating the problems associated with optical reflectivity variations.
Solution Approach 2:
The patent introduces processing gas as an intermediary medium to transfer information about wafer position. The processing gas fills the gap between the wafer and processing body, and its pressure serves as an indirect but reliable indicator of the gap width. This intermediary approach allows measurement without direct contact with the wafer and without being affected by wafer surface properties.
2Measurement precision
If mechanical measurements are used to determine position, then measurement capability is provided, but device complexity increases and contact is required
Solution Approach 1:
The patent makes the processing gas serve a dual function: it performs the intended processing function and simultaneously serves as the measurement medium. The same gas that is used for semiconductor processing also provides the pressure signal that indicates wafer position. This self-service approach eliminates the need for separate measurement systems, reducing device complexity while maintaining measurement capability.
Solution Approach 2:
The processing gas is given multiple functions: it performs the semiconductor processing function and simultaneously serves as the measurement medium for determining wafer position. This multi-functionality reduces the overall system complexity by eliminating the need for separate mechanical measurement systems, sensors, or actuators.
3Manufacturing precision
If mechanical contact with wafer is used for positioning, then positioning control is achieved, but wafer integrity deteriorates due to potential damage
Solution Approach 1:
The patent uses pneumatic pressure of the processing gas to control and indicate wafer position without mechanical contact. The gas pressure provides a contactless means to sense and control the gap between the wafer and processing body, eliminating the risk of mechanical damage while maintaining positioning accuracy. The processing gas acts as a cushion that supports the wafer without physical contact.
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 non-contact monitoring of wafer positioning and thickness measurements, ensuring reliable system performance and high-quality processing results by correlating pressure changes with gap width and alignment variations.
Implementation Method 1
repeatedly measuring a pressure of the processing gas within the gas flow; and determining from the pressure measurements the occurrence of an event that is related to a variation in the position of the wafer's first main surface relative to the surface of the first processing body
Implementation Method 2
effecting a flow of processing gas that extends through the at least one gas conduit and through the gap between the first processing body's surface and the wafer's first main surface
Data Source
AI summary
Disclosed is a method involving repeatedly measuring a pressure within a flow of processing gas that is provided in a semiconductor processing apparatus for treatment of a semiconductor substrate, such as a semiconductor wafer. The flow of processing gas is made to extend between a surface of the substrate and a surface of a processing body. From the pressure measurements the occurrence of an event that is related to a variation in the position of the substrate's surface relative to the surface of the processing body is determined.