Inductively Coupled Plasma Current Ratio Adjustment

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Solution Overview

Problem

Current plasma processing systems require multiple variable capacitors and step motors, leading to high manufacturing, maintenance, and operating costs, as well as reliability issues due to numerous mechanical moving parts, and offer limited current ratio adjustment, resulting in unstable plasma and potential production yield failures.

Innovation Solution

A plasma processing system utilizing a parallel inductor-capacitor circuit with a single variable capacitor to adjust the current ratio between coils, reducing mechanical parts and costs while enabling a wider current ratio range through resonance effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple variable capacitors and step motors are used to adjust current ratios, then current ratio adjustment capability is improved, but manufacturing cost, maintenance cost, and operating cost increase significantly

Engineering Contradiction:

Improvecurrent ratio adjustment capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple current adjustment functions into a single variable capacitor by using a current splitter circuit with adjustable tapping points. Instead of requiring separate variable capacitors for each coil, the invention uses one variable capacitor to control the current distribution to multiple coils simultaneously, thereby reducing component count and manufacturing cost while maintaining current ratio adjustment capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single variable capacitor in the invention performs multiple functions: it adjusts the current ratio for inner coil, outer coil, and can be extended to additional coils. The current splitter circuit provides universal current distribution control to multiple coils through adjustable tapping points, eliminating the need for dedicated adjustment components for each coil.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple variable capacitors and step motors are used to adjust current ratios, then current ratio adjustment capability is improved, but reliability deteriorates due to numerous mechanical moving parts

Engineering Contradiction:

Improvecurrent ratio adjustment capabilityVSAvoidsystem reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention replaces multiple step motors and mechanical variable capacitors with a single variable capacitor controlled by a digital-to-analog converter (DAC) and digital control logic. This substitution eliminates mechanical moving parts from the current adjustment mechanism, significantly improving reliability while maintaining the ability to adjust current ratios through electronic control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control system uses the existing plasma detection capabilities to automatically adjust the current ratios without requiring manual intervention or complex mechanical adjustment mechanisms. The system self-regulates the current distribution based on real-time plasma conditions, reducing the need for mechanical adjustment components.

Inventive Principle:

Principle #25Self-service

3Device complexity

If traditional power splitter with limited current ratio range is used, then system complexity is reduced, but plasma stability deteriorates due to limited adjustment range

Engineering Contradiction:

Improvepower splitter complexityVSAvoidplasma stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The invention implements dynamic current ratio adjustment by making the current splitter circuit configurable through software control. The adjustable tapping points on the current splitter allow the system to adapt the current distribution in real-time based on plasma conditions, providing a wide effective adjustment range that maintains plasma stability without requiring overly complex hardware.

Inventive Principle:

Principle #15Dynamics

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 solution significantly reduces costs and improves reliability by minimizing mechanical parts and expanding the current ratio range, ensuring stable plasma and meeting more stringent production yield and device feature requirements.

Implementation Method 1

enabling a wider current ratio range through resonance effects

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9305750B2Adjusting current ratios in inductively coupled plasma processing systems

Publication Date: 2016.04.05 LAM RES CORP

AI summary

A plasma processing system for generating plasma to process at least a wafer. The plasma processing system may include a first coil for conducting a first current for sustaining at least a first portion of the plasma. The plasma processing system may also include a second coil for conducting a second current for sustaining at least a second portion of the plasma. The plasma processing system may also include a power source for powering the first current and the second current. The plasma processing system may also include a parallel circuit for adjusting one of the amperage of the first current and the amperage of the second current. The parallel circuit may be electrically coupled between the power source and at least one of the first coil and the second coil. The parallel circuit may include an inductor and a variable capacitor electrically connected in parallel to each other.