Electrokinetic Particle Removal from Semiconductor Substrates

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Solution Overview

Problem

Conventional methods for removing particles from semiconductor substrates, especially those smaller than 100 nanometers, are inefficient and can cause turbulence or redeposition, leading to prolonged cleaning cycles and potential damage to sensitive structures.

Innovation Solution

The use of electrokinetic forces, including electrophoresis and electroosmosis, to assist in transferring particles into a flowing liquid, reducing the need for aggressive mechanical cleaning and enhancing the removal of particles by applying voltage differentials and modifying the liquid's pH, ionic strength, and temperature to overcome Van der Waals forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional mechanical cleaning methods (rinses, megasonic agitation) are used to remove particles, then particle removal capability is improved, but cleaning time increases and mechanical stress on substrates increases

Engineering Contradiction:

Improveparticle removal capabilityVSAvoidcleaning cycle duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces aggressive mechanical cleaning methods with electrostatic field-based particle removal. By applying voltage differentials between electrodes, particles are removed through electrostatic forces rather than mechanical agitation, thereby reducing cleaning time while maintaining effective particle removal capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent modifies the physical-chemical parameters of the cleaning environment by controlling pH, ionic strength, and temperature of the liquid medium. These parameter changes optimize particle removal efficiency while reducing the need for prolonged mechanical cleaning cycles.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If aggressive mechanical cleaning methods are used to remove particles, then particle removal capability is improved, but damage to sensitive structures increases

Engineering Contradiction:

Improveparticle removal capabilityVSAvoidmechanical stress on substrates

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent substitutes mechanical cleaning forces with electrostatic field forces. By using voltage differentials to generate electrostatic attraction and repulsion between electrodes and particles, the method achieves effective particle removal without the mechanical stress and turbulence associated with conventional megasonic agitation and rinsing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an electrostatic field as an intermediary mechanism between the cleaning system and particles. This field-mediated approach allows particle removal through non-contact electrostatic forces, eliminating direct mechanical contact and reducing damage to sensitive semiconductor structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If conventional rinsing and agitation methods are used, then particle removal is achieved, but turbulence and redeposition occur

Engineering Contradiction:

Improveparticle removalVSAvoidturbulence and redeposition

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces mechanical agitation and rinsing with electrostatic field-based particle manipulation. By applying controlled voltage differentials, particles are removed through electrostatic forces without generating turbulence in the liquid medium, thereby preventing redeposition and improving overall particle removal effectiveness.

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 reduces cleaning time, minimizes mechanical stress on semiconductor substrates, and effectively removes particles of various sizes, including those smaller than 100 nanometers, by utilizing electrokinetic forces to dislodge and transport particles through the boundary layer into the bulk flow region.

Implementation Method 1

The electrokinetic forces may utilize one or both of electrophoresis (i.e., movement of charged particles in an electric field) and electroosmosis

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Implementation Method 2

The electrokinetic forces may utilize one or both of electrophoresis (i.e., movement of charged particles in an electric field) and electroosmosis

Methodology Applied

Scientific EffectElectroosmosis: Electro-Osmosis

Implementation Method 3

The utilization of electrokinetic forces may reduce cleaning times. Further, in conventional methods that utilize hydrodynamic forces there is often an aggressive mechanical aspect of the cleaning. Such aggressive aspect is utilized to enhance dislodgment of particles from a semiconductor substrate surface

Methodology Applied

Scientific EffectVan der Waals forces: Van der Waals Force

Data Source

PatentUS11139159B2Methods of removing particles from over semiconductor substrates

Publication Date: 2021.10.05 MICRON TECHNOLOGY INC

AI summary

Some embodiments include methods of removing particles from over surfaces of semiconductor substrates. Liquid may be flowed across the surfaces and the particles. While the liquid is flowing, electrophoresis and/or electroosmosis may be utilized to enhance transport of the particles from the surfaces and into the liquid. In some embodiments, temperature, pH and/or ionic strength within the liquid may be altered to assist in the removal of the particles from over the surfaces of the substrates.