Interdigitated Capacitive Gas Sensor for ppm Process Control
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Solution Overview
Problem
Current mass flow meters and valves lack the necessary resolution for precise control of gas concentrations in advanced nano-scale semiconductor manufacturing processes, and laser sensors are complex and difficult to integrate into high volume manufacturing environments.
Innovation Solution
The development of capacitive gas concentration sensors with interdigitated electrodes, which can be easily integrated into semiconductor processing tools to provide high precision gas concentration measurements down to parts per million levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass flow meters and valves are used to control gas concentration, then the system is simple and cost-effective, but the measurement precision and control resolution are insufficient for advanced nano-scale manufacturing
Solution Approach 1:
The patent replaces complex mechanical laser sensing systems with a simplified capacitive sensor system that uses electrical fields to detect gas concentration. The capacitive sensor measures changes in capacitance caused by gas molecules affecting the electrical field between interdigitated electrodes, eliminating the need for complex optical components while achieving parts-per-million measurement precision.
Solution Approach 2:
The patent changes the measurement parameter from optical properties (laser absorption) to electrical properties (capacitance). By measuring capacitance changes in response to gas concentration variations, the system achieves high precision measurement with simpler, more manufacturable components suitable for high volume manufacturing environments.
2Measurement precision
If laser sensors are used to achieve accurate gas concentration control, then measurement precision improves, but device complexity and integration difficulty increase significantly
Solution Approach 1:
The patent replaces mechanical laser sensing systems with a simplified capacitive sensor system that uses electrical fields to detect gas concentration. The capacitive sensor measures changes in capacitance caused by gas molecules affecting the electrical field between interdigitated electrodes, eliminating the need for complex optical components while achieving parts-per-million measurement precision.
Solution Approach 2:
The capacitive sensor uses inexpensive, easily fabricated interdigitated electrode structures that can be mass-produced using standard semiconductor fabrication techniques. These simple electrode patterns on substrates are far more cost-effective and easier to manufacture than laser sensors, enabling high volume manufacturing integration.
3Measurement precision
If mass flow meters and valves are used to set gas flow, then the system is easy to operate, but the control resolution is insufficient for precise gas concentration monitoring
Solution Approach 1:
The capacitive sensor provides direct real-time feedback on actual gas concentration levels by measuring capacitance changes. This enables closed-loop control where the sensor output can be fed back to adjust mass flow controllers, achieving precise concentration control with better resolution than open-loop flow control alone.
Solution Approach 2:
The patent replaces indirect mechanical flow control monitoring with direct electrical field-based concentration measurement. The capacitive sensor directly measures gas concentration through capacitance changes, providing superior resolution compared to inferring concentration from flow rate measurements.
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
The capacitive sensors enable precise control of gas concentrations, improving the accuracy and efficiency of semiconductor processing by providing a cost-effective and easily integratable solution for high volume manufacturing environments.
Implementation Method 1
capacitive sensor comprises a first electrode... the gas concentration sensor further comprises a second electrode... second fingers that are interdigitated with the first fingers
Data Source
AI summary
Embodiments disclosed herein include gas concentration sensors, and methods of using such gas concentration sensors. In an embodiment, a gas concentration sensor comprises a first electrode. In an embodiment the first electrode comprises first fingers. In an embodiment, the gas concentration sensor further comprises a second electrode. In an embodiment, the second electrode comprises second fingers that are interdigitated with the first fingers.