Etching Endpoint Detection via Exhaust Flow Valve Control

Solution Overview

Problem

Chemical dry etching processes in semiconductor fabrication lack an effective method to determine the endpoint, leading to prolonged processing times and increased gas usage due to the inability to monitor and control the etching process efficiently.

Innovation Solution

A wafer fabricating system that utilizes a gas exhausting module with a valve having a variable open ratio, controlled by a control module, to regulate the exhaust flow and determine the etching endpoint based on the valve's open ratio, allowing for precise control of gas pressure and flow rates within the etching chamber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If chemical dry etching process is performed without endpoint monitoring, then the etching chamber can operate continuously, but the processing time is prolonged and gas usage increases due to inability to determine etching endpoint

Engineering Contradiction:

Improvegas usageVSAvoidprocess monitoring system

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The system implements feedback control by continuously monitoring the exhaust flow rate through a flow sensor and comparing it against reference values. When the measured exhaust flow rate deviates from the reference by more than a threshold, the system generates an endpoint alert, enabling real-time process adjustment and optimization of gas usage.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces traditional mechanical endpoint detection methods with a sensor-based monitoring system that measures exhaust flow rate electronically. This substitution enables more precise and automated endpoint detection, reducing reliance on manual intervention and mechanical measurement systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If chemical dry etching process is performed without endpoint monitoring, then the system structure remains simple, but the processing time is prolonged due to inability to determine etching endpoint

Engineering Contradiction:

Improveprocessing timeVSAvoidprocess monitoring system

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system implements feedback control by continuously monitoring the exhaust flow rate through a flow sensor and comparing it against reference values. When the measured exhaust flow rate deviates from the reference by more than a threshold, the system generates an endpoint alert, enabling real-time process adjustment and optimization of gas usage.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces traditional mechanical endpoint detection methods with a sensor-based monitoring system that measures exhaust flow rate electronically. This substitution enables more precise and automated endpoint detection, reducing reliance on manual intervention and mechanical measurement systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If variable open ratio valve is introduced to regulate exhaust flow, then the etching endpoint can be precisely determined, but the device complexity increases

Engineering Contradiction:

Improveendpoint determination precisionVSAvoidvalve control system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system employs a variable open ratio valve that can dynamically adjust the exhaust flow rate based on real-time process conditions. The valve's open ratio is modulated according to the measured exhaust flow rate and reference values, enabling precise control and endpoint detection through dynamic adjustment rather than fixed positioning.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements feedback control by continuously monitoring the exhaust flow rate through a flow sensor and comparing it against reference values. When the measured exhaust flow rate deviates from the reference by more than a threshold, the system generates an endpoint alert, enabling real-time process adjustment and optimization of gas usage.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11183391B2Method for real time monitoring semiconductor fabrication process

Publication Date: 2021.11.23 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method for processing semiconductor wafer is provided. The method includes supplying a processing gas into an etching chamber containing a semiconductor wafer. The method also includes detecting a pressure in the etching chamber. The method further includes regulating an exhaust flow from the etching chamber by adjusting an open ratio of a valve according to a data in relation to a pressure in the etching chamber produced by the pressure sensor. In addition, the method includes determining an etching endpoint based on the open ratio of the valve.