Substrate Plasma Processing with Intermittent High-Frequency Power

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Solution Overview

Problem

Conventional substrate plasma processing apparatuses face challenges in controlling ion energy distribution, leading to inefficient processing shapes and plasma instability due to wide ion energy bands and electron temperature fluctuations, especially when using DC negative pulses and high-frequency RF superposition.

Innovation Solution

A substrate plasma processing apparatus and method that employs intermittent high-frequency power and synchronized DC negative pulse application to control ion energy distribution, maintaining plasma stability and optimizing processing conditions by ensuring the DC negative pulses are applied only during high-frequency power cycles, preventing afterglow states and charge-up issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If DC negative pulse voltage is applied continuously to control ion energy, then processing precision is improved, but plasma instability occurs due to electron temperature fluctuations

Engineering Contradiction:

Improveprocessing precisionVSAvoidplasma stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent applies periodic pulsed DC negative voltage instead of continuous voltage to control ion energy. The pulsed nature of the voltage allows plasma to stabilize between pulses while still achieving the desired ion energy control during the pulse periods, thereby resolving the contradiction between processing precision and plasma stability.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent dynamically adjusts the DC negative pulse voltage parameters (amplitude, width, frequency) based on plasma conditions and processing requirements. This dynamic control enables optimization of both ion energy for processing precision and pulse timing for plasma stability, resolving the contradiction between these two parameters.

Inventive Principle:

Principle #15Dynamics

2Quantity of substance

If high frequency RF power is applied to generate plasma, then plasma density is improved, but ion energy distribution becomes too wide causing processing shape deterioration

Engineering Contradiction:

Improveplasma densityVSAvoidprocessing shape

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent changes the energy distribution parameters by applying DC negative pulse voltage superimposed on the high frequency RF power. This parameter change narrows the ion energy distribution while maintaining the plasma density generated by the RF power, thereby resolving the contradiction between plasma density and processing shape quality.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If DC negative pulse voltage is applied during high frequency power cycles, then ion energy control is improved, but charge-up issues occur in insulator regions

Engineering Contradiction:

Improveion energy controlVSAvoidcharge-up

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent uses periodic pul DC negative voltage with controlled pulse width and frequency to limit the total charge deposited on insulator regions. The periodic nature allows charge to dissipate between pulses, preventing excessive charge-up while still achieving effective ion energy control during the pulse periods.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent maintains continuous plasma generation through high frequency RF power while applying intermittent DC negative pulses for ion energy control. This continuous plasma action ensures that charge can be neutralized between pulses, preventing charge-up issues while maintaining effective ion energy control.

Inventive Principle:

Principle #20Continuity of useful 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 approach narrows the ion energy band, stabilizes plasma, enhances processing accuracy, and reduces plasma damage, achieving improved etching performance and film formation quality by maintaining stable electron temperature and radical species density.

Implementation Method 1

a high frequency power supply configured to apply a high frequency power to an electrode

Methodology Applied

Scientific EffectHigh frequency power: Electromagnetic Induction

Implementation Method 2

a DC negative pulse voltage is superimposed on the high frequency power applied to the electrode

Methodology Applied

Scientific EffectIon acceleration by electric field: Electric Field

Implementation Method 3

plasma generated between the electrodes

Methodology Applied

Scientific EffectPlasma generation: Ionisation

Data Source

PatentUS8821684B2Substrate plasma processing apparatus and plasma processing method

Publication Date: 2014.09.02 KIOXIA CORP

AI summary

A substrate plasma processing apparatus includes a substrate holding electrode and a counter electrode which are arranged in a chamber, a high frequency generating device which applies a high frequency of 50 MHZ or higher to the substrate holding electrode, a DC negative pulse generating device which applies a DC negative pulse voltage in a manner of superimposing on the high frequency, and a controller controlling to cause intermittent application of the high frequency and cause intermittent application of the DC negative pulse voltage according to the timing of on or off of the high frequency.