Edge Ring Voltage Control for Plasma Sheath Uniformity

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Solution Overview

Problem

Existing plasma processing chambers face challenges with edge ring erosion, leading to distorted plasma sheaths and reduced process uniformity at the substrate edge, which decreases yield and requires frequent replacement of the edge ring, causing downtime and increased costs.

Innovation Solution

The solution involves manipulating the voltage at the edge ring using an electrostatic chuck with a chucking electrode, a baseplate, and an edge ring electrode coupled to a variable capacitor and RF power source, allowing for adjustment of the plasma sheath to maintain process uniformity and compensate for edge ring erosion without moving parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the edge ring is used to surround the substrate during plasma processing, then the plasma processing can be performed, but the edge ring erodes and requires replacement after a predetermined interval

Engineering Contradiction:

Improveplasma processing capabilityVSAvoidedge ring service life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent applies parameter changes by controlling the voltage at the edge ring through a circuit with a variable capacitor. By adjusting the voltage parameter, the plasma sheath is manipulated to compensate for edge ring erosion, maintaining processing quality and extending the edge ring's service life without requiring frequent replacement.

Inventive Principle:

Principle #35Parameter changes

2Shape

If the edge ring is severely eroded, then the plasma sheath shape distorts, but this causes undesirable processing effects at the substrate edge

Engineering Contradiction:

Improveplasma sheath shapeVSAvoidprocess uniformity at substrate edge

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The patent implements preliminary anti-action by proactively controlling the edge ring voltage to prevent plasma sheath distortion before it occurs. The circuit with variable capacitor allows adjustment of voltage to counteract the erosive effects on the edge ring, maintaining proper plasma sheath geometry and preventing undesirable processing effects at the substrate edge.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent employs feedback control by monitoring the edge ring voltage and plasma sheath characteristics, then adjusting the voltage through the variable capacitor circuit to maintain optimal plasma sheath shape. This closed-loop control ensures process uniformity at the substrate edge even as the edge ring erodes over time.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If movable edge rings are used to control plasma sheath, then the plasma sheath can be adjusted, but moving parts are undesirable for electronic device manufacturing processes with stringent particle requirements

Engineering Contradiction:

Improveplasma sheath control capabilityVSAvoidparticle contamination risk

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the mechanical movable edge ring system with an electrical control system. Instead of physically moving the edge ring to adjust the plasma sheath, the invention uses a circuit with variable capacitor to control the voltage at the stationary edge ring, thereby manipulating the plasma sheath shape. This eliminates moving parts and associated particle contamination risks while maintaining plasma sheath control capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 extends the life of the edge ring by adjusting the plasma sheath to maintain process uniformity, reducing downtime and replacement costs, while ensuring consistent plasma processing characteristics across the substrate.

Implementation Method 1

a circuit including a first variable capacitor coupled to the edge ring electrode

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

an electrostatic chuck having a chucking electrode embedded therein for chucking a substrate to the electrostatic chuck

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 3

a baseplate underneath the substrate to feed radio frequency (RF) power to the substrate

Methodology Applied

Scientific EffectRadio frequency heating: Dielectric Heating

Data Source

PatentUS11908661B2Apparatus and methods for manipulating power at an edge ring in plasma process device

Publication Date: 2024.02.20 APPLIED MATERIALS INC

AI summary

The present disclosure relates to apparatus and methods that manipulate the amplitude and phase of the voltage or current of an edge ring. The apparatus includes an electrostatic chuck having a chucking electrode embedded therein for chucking a substrate to the electrostatic chuck. The apparatus further includes a baseplate underneath the substrate to feed power to the substrate. The apparatus further includes an edge ring disposed over the electrostatic chuck. The apparatus further includes an edge ring electrode located underneath the edge ring. The apparatus further includes a circuit including a first variable capacitor coupled to the edge ring electrode.