Substrate Processing Apparatus RF Power Control

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Solution Overview

Problem

In substrate processing, maintaining a balance between RF power supply for plasma generation and bias power supply is challenging, leading to abnormal discharge and potential damage to RF matching units due to excessive amplitude of bias RF power, and heat generation from DC voltage applications.

Innovation Solution

A substrate processing method and apparatus that intermittently control the output of RF power applying units and DC voltage applying units based on predetermined timings to prevent excessive amplitude and heat generation, ensuring stable operations by adjusting the ON/OFF states and power levels of these units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RF power supply for plasma generation and bias power supply are operated simultaneously without timing control, then plasma generation and ion bombardment can proceed, but the amplitude of bias RF power becomes excessively large causing abnormal discharge and damage to RF matching units

Engineering Contradiction:

Improvestability of substrate processVSAvoidabnormal discharge and damage to RF matching unit

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies periodic pulsing control to both the excitation RF power supply and bias RF power supply, making them operate in synchronized cycles. The excitation power is pulsed at a first frequency while the bias power is pulsed at a second frequency, ensuring that bias power is never applied when excitation power is off. This periodic action prevents excessive amplitude buildup and abnormal discharge while maintaining reliable substrate processing.

Inventive Principle:

Principle #19Periodic action

2Power

If DC voltage is continuously applied to the lower electrode, then ion bombardment energy can be maintained, but excessive heat is generated causing potential damage to the electrode and matching unit

Engineering Contradiction:

Improveion bombardment energyVSAvoidheat generation from DC voltage

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The patent implements periodic pulsing of the DC voltage applying unit in synchronization with the RF power supplies. The DC voltage is applied only during specific phases when both RF powers are active, and is turned off during other phases. This periodic application maintains necessary ion bombardment energy while providing cooling intervals that prevent excessive heat accumulation and potential damage to the electrode and matching unit.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If independent ON/OFF control is applied to excitation and bias RF power supplies, then flexible process control can be achieved, but timing imbalance causes excessive bias RF power amplitude

Engineering Contradiction:

Improveprocess control flexibilityVSAvoidamplitude control of bias RF power

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs a control unit that monitors and coordinates the operating states of both RF power supplies. The control unit receives feedback on the timing and amplitude of excitation RF power and adjusts the bias RF power supply accordingly, ensuring that bias power amplitude remains within safe limits. This feedback mechanism maintains process control flexibility while preventing amplitude-related reliability issues.

Inventive Principle:

Principle #23Feedback

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

Prevents abnormal discharge and damage to RF matching units by controlling RF power amplitude and reduces heat generation from DC voltage applications, optimizing the processing time for reaction products and ensuring efficient plasma generation.

Implementation Method 1

a first RF power applying unit for applying an RF power for plasma generation into the chamber

Methodology Applied

Scientific EffectPlasma generation through RF excitation: Plasma

Implementation Method 2

a plasma-generating gas is prevented from being dissociated by performing a pulse control of RF power for plasma generation

Methodology Applied

Scientific EffectGas dissociation through RF power: Photodissociation

Implementation Method 3

a second RF power applying unit for applying an RF power for bias to the lower electrode

Methodology Applied

Scientific EffectIon acceleration through RF bias: Lorentz Force

Implementation Method 4

a DC voltage applying unit for applying a DC voltage for bias to the lower electrode

Methodology Applied

Scientific EffectIon energy control through DC bias: Electric Field

Data Source

PatentUS9564287B2Substrate processing apparatus and substrate processing method using same

Publication Date: 2017.02.07 TOKYO ELECTRON LTD

AI summary

A substrate processing method uses a substrate processing apparatus including a chamber for accommodating a substrate, a lower electrode to mount the substrate, a first RF power applying unit for applying an RF power for plasma generation into the chamber, and a second RF power applying unit for applying an RF power for bias to the lower electrode. The RF power for plasma generation is controlled to be intermittently changed by changing an output of the first RF power applying unit at a predetermined timing. If no plasma state or an afterglow state exists in the chamber by a control of the first RF power applying unit, an output of the second RF power applying unit is controlled to be in an OFF state or decreased below an output of the second RF power applying unit when the output of the first RF power applying unit is a set output.