Plasma Ignition Sequence Reduces Surface Particle Contamination

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Solution Overview

Problem

Plasma processing systems in semiconductor fabrication face challenges with particle contamination during plasma etch processes, leading to yield loss in integrated circuit manufacturing due to the introduction of surface particles during plasma ignition.

Innovation Solution

A discharge ignition sequence using a secondary RF power source to ignite the process gas before clamping the microelectronic workpiece, reducing electrical and physical perturbations, which minimizes the number of particles introduced into the plasma and subsequently reduces defects on the workpiece surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional plasma ignition sequence is used, then plasma is successfully ignited for processing, but surface particles are introduced onto the workpiece causing contamination

Engineering Contradiction:

Improveplasma ignition reliabilityVSAvoidsurface particle contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The workpiece is clamped to the holder before plasma ignition occurs. This preliminary clamping action ensures that the workpiece is securely positioned and electrically connected to the holder before the high-energy plasma discharge begins, preventing particle generation and contamination during the critical ignition phase

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If the workpiece is clamped before plasma ignition, then particle contamination is reduced, but the electrical connection and clamping force may be insufficient during the high-current ignition phase

Engineering Contradiction:

Improvesurface particle contaminationVSAvoidclamping force

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The system dynamically adjusts the clamping force during the plasma ignition sequence. The holder provides enhanced electrical connection and increased clamping force during the high-current ignition phase, then maintains adequate clamping during plasma maintenance. This dynamic adjustment ensures both sufficient clamping strength during ignition and particle contamination prevention throughout the process

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If a secondary RF power source is used for ignition, then particle density in plasma is reduced, but the system complexity increases

Engineering Contradiction:

Improveparticle density in plasmaVSAvoidpower source configuration

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The holder serves multiple functions: it provides mechanical support for the workpiece, electrical connection for RF power delivery, and electrostatic clamping capability. By making the holder multi-functional, the system reduces the need for separate dedicated components for each function, thereby reducing overall system complexity while achieving the benefit of reduced particle density through the secondary RF power source ignition sequence

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively decreases surface particle contamination and improves yields in integrated circuit manufacturing by reducing the density of particles in the plasma, thereby minimizing defects on the microelectronic workpieces.

Implementation Method 1

a second RF power source configured to couple RF power to the holder, and ignite the process gas to form plasma by activating the second RF power source such that sufficient RF power is coupled to the holder for plasma ignition

Methodology Applied

Scientific EffectRF power coupling: Electromagnetic Induction

Implementation Method 2

a direct current (DC) power supply configured to couple a positive voltage to the holder. Subsequent to igniting the process gas to form plasma, the method further includes clamping the microelectronic workpiece to the holder by applying the positive voltage to the holder with the DC power supply

Methodology Applied

Scientific EffectElectrostatic clamping: Electrostatics

Data Source

PatentUS10818502B2System and method of plasma discharge ignition to reduce surface particles

Publication Date: 2020.10.27 TOKYO ELECTRON LTD

AI summary

Systems and methods are disclosed for plasma discharge ignition to reduce surface particles and thereby decrease defects introduced during plasma processing. A microelectronic workpiece is positioned on a holder within a process chamber that includes a first radio frequency (RF) power source configured to couple RF power to a top portion of the process chamber, a second RF power source configured to couple RF power to the holder, and a direct current (DC) power supply. Initially, a process gas for plasma process is flowed into the process chamber. The process gas is ignited to form plasma by activating the second RF power source to apply RF power to the holder. Subsequently, the microelectronic workpiece is clamped to the holder by applying the positive voltage to the holder with the DC power supply, and the first RF power source is activated to maintain the plasma within the process chamber.