Edge Ring DC Voltage Control for Plasma Etching

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Solution Overview

Problem

Existing plasma processing methods face challenges in applying a DC voltage to an edge ring without causing a shift in plasma characteristics across the entire substrate, leading to inconsistent etching rates and product quality.

Innovation Solution

A plasma processing method that involves generating plasma, applying a DC voltage to an edge ring, measuring initial and subsequent voltages, and calculating a parameter to control the DC voltage based on the sheath thickness variation, thereby minimizing plasma characteristic shifts and maintaining accurate control over the peripheral edge region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a DC voltage is applied to the edge ring, then the tilting angle control is improved, but plasma characteristics shift across the entire substrate

Engineering Contradiction:

Improvetilting angle controlVSAvoidplasma characteristics

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent applies a DC voltage to the edge ring to change the electric field distribution and control the tilting angle. By adjusting the voltage parameter, the plasma sheath thickness at the edge is modified, enabling precise control of the etching profile while maintaining plasma stability through controlled parameter variation.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If plasma is generated inside the chamber, then the processing capability is enabled, but voltage measurement accuracy is reduced due to plasma interference

Engineering Contradiction:

Improveprocessing capabilityVSAvoidvoltage measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent measures the open circuit voltage of the edge ring before applying the DC voltage during plasma processing. By performing the voltage measurement preliminarily, before the plasma is fully generated and before the DC voltage is applied, the measurement is taken under conditions with minimal plasma interference, ensuring accurate baseline voltage data for subsequent processing.

Inventive Principle:

Principle #10Preliminary action

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

This method allows for uniform control of the DC voltage applied to the edge ring, minimizing shifts in plasma characteristics and etching rates across the substrate, ensuring consistent product quality and precise control of the tilting angle.

Implementation Method 1

generating plasma inside a chamber

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 2

applying a DC voltage to an edge ring disposed to surround a substrate while generating the plasma

Methodology Applied

Scientific EffectElectric Field: Electric Field

Data Source

PatentUS11682543B2Plasma processing method and plasma processing apparatus

Publication Date: 2023.06.20 TOKYO ELECTRON LTD

AI summary

A plasma processing method is provided. In the plasma processing method, plasma is generated inside a chamber. A DC voltage is applied to an edge ring disposed to surround a substrate while generating the plasma. A first voltage of the edge ring is acquired while applying the DC voltage. Then, the application of the DC voltage is stopped. A second voltage of the edge ring is acquired while stopping the application of the DC voltage. Then, a parameter for controlling the DC voltage is calculated based on the first voltage and the second voltage.