Crystal Microbalance Gas Flow Control for ALD Precision

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Solution Overview

Problem

Current advanced process control techniques in integrated circuit manufacturing, such as PID feedback control, are not sufficiently precise and cost-effective for maintaining consistent gas composition and concentration in atomic layer deposition (ALD) and etching (ALE) processes, leading to wafer-to-wafer variations and potential faults.

Innovation Solution

Incorporating a crystal microbalance (CM), like a quartz crystal microbalance (QCM), into gas flow lines entering and exiting processing chambers to accurately monitor mass flow rates of gases in real time, enabling precise adjustments and detection of contamination or system failures, thereby ensuring consistent gas flow and process control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If current APC techniques (PID feedback control) are used to control gas flow, then process control is implemented, but measurement precision and manufacturing precision are insufficient leading to wafer-to-wafer variations

Engineering Contradiction:

Improvegas flow measurement precisionVSAvoidwafer-to-wafer consistency

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent replaces conventional mechanical flow control systems with a crystal microbalance-based measurement system. The CM uses a piezoelectric crystal that changes resonance frequency in response to mass changes on its surface, providing highly precise mass flow measurements that substitute for less accurate mechanical flow meters and enable superior process control precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent monitors and controls the mass flow rate parameter of gases using the crystal microbalance. By measuring the resonance frequency shifts of the crystal in response to gas mass changes, the system detects precise variations in gas flow parameters, enabling real-time adjustments to maintain manufacturing precision and eliminate wafer-to-wafer variations.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If advanced process control is implemented to improve precision, then gas flow control is enhanced, but system cost increases

Engineering Contradiction:

Improvegas composition consistencyVSAvoidsystem cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent employs a crystal microbalance that provides high-precision measurement capabilities at a lower cost compared to conventional advanced process control systems. The CM is a relatively simple, cost-effective device that delivers superior measurement precision without requiring complex infrastructure, making precise gas flow control more economically accessible.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If real-time gas flow monitoring is implemented, then process control precision is improved, but device complexity increases

Engineering Contradiction:

Improvereal-time mass flow measurementVSAvoidcontrol system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the measurement function from complex flow control systems and isolates it in a dedicated crystal microbalance device. The CM specifically measures mass flow parameters through crystal resonance, separating the measurement task from the overall control system and providing precise data without requiring complex integrated control mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

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 CM-based system provides precise and cost-effective process monitoring, allowing for real-time adjustments to maintain desired gas flow rates and preventing faults by detecting deviations or contamination, thus enhancing the consistency and reliability of ALD and ALE processes.

Implementation Method 1

a CM can measure the resonance of a crystal sensor (e.g., a quartz crystal sensor) contained therein as gas flows over that crystal sensor and can, thereby be used to accurately monitor, in real time, the mass flow rate of the gas

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS10256126B2Gas flow process control system and method using crystal microbalance(s)

Publication Date: 2019.04.09 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Disclosed are process control systems and methods incorporating a crystal microbalance (CM) (e.g., a quartz crystal microbalance (QCM)) into gas flow line(s) entering and/or exiting a processing chamber. A CM measures the resonance of a quartz crystal sensor contained therein as gas flows over that crystal sensor and can, thereby be used to accurately monitor, in real time, the mass flow rate of the gas. The mass flow rate may indicate that gas contamination has occurred and, in response, a controller can cause the gas flow to stop. Additionally, the mass flow rate may indicate the desired result will not be achieved within the processing chamber and, in response, advanced process control (APC) can be performed (e.g., the controller can adjust the gas flow). CM(s) incorporated into gas flow lines entering and/or exiting a processing chamber can provide precise measurements for process monitoring at minimal cost.