Alkaline Electrolyte Planarization for Fast, Low-Roughness ECMP

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Solution Overview

Problem

Conventional electro-chemical mechanical polishing (ECMP) methods often result in scratches and increased surface roughness when attempting to increase processing speed, due to agglomerated sludge adhesion and high oxide film hardness, which distorts the processing surface.

Innovation Solution

The method involves using an alkaline electrolyte solution to control zeta potentials and reduce oxide film hardness, allowing for efficient removal of the oxide film at lower pressures and improving processing speed while maintaining suitable surface roughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional ECMP methods are used to increase processing speed, then productivity is improved, but surface roughness increases due to scratches and distortion

Engineering Contradiction:

Improveprocessing speedVSAvoidsurface roughness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical parameters of the electrolyte solution by using an alkaline electrolyte with controlled pH (9-13) and specific composition (containing hydroxide ions and carbonate ions). This parameter change modifies the anodic oxidation process to form softer oxide films that can be removed at lower pressures, thereby maintaining surface quality while improving processing speed

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces the alkaline electrolyte solution as an intermediary medium between the workpiece and the polishing wheel. This electrolyte mediates the electrochemical reaction to form oxide films with controlled properties (softer, more removable), enabling faster processing without compromising surface finish

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If pressure is increased to remove oxide film faster, then productivity is improved, but surface distortion and scratches increase

Engineering Contradiction:

Improveoxide film removal speedVSAvoidsurface flatness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the physical-chemical parameters of the oxide film by controlling the anodic oxidation process in alkaline electrolyte. This results in oxide films with modified hardness and adhesion properties that can be removed at lower pressures, thus improving removal speed without causing surface distortion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent partially replaces the mechanical removal mechanism with an electrochemical mechanism. The anodic oxidation process chemically forms and softens the oxide film, reducing the reliance on mechanical abrasion and enabling removal at lower pressures that preserve surface flatness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If conventional electrolyte is used, then processing is simpler, but sludge agglomeration occurs causing scratches

Engineering Contradiction:

Improveelectrolyte composition complexityVSAvoidsurface quality

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by using an alkaline electrolyte with specific pH range (9-13) and controlled ionic composition. This parameter change prevents sludge agglomeration by controlling the electrochemical reactions, thereby preventing scratches while maintaining manageable process complexity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful effect of sludge generation into a beneficial outcome by using alkaline electrolyte that controls sludge formation. The electrolyte chemistry transforms the sludge from an agglomerating, scratch-causing byproduct into a controlled, non-agglomerating residue that does not compromise surface quality

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 enables high processing speed with reduced surface roughness and improved manufacturing efficiency by suppressing sludge agglomeration and oxide film hardness, achieving effective planarization of semiconductor materials like SiC wafers.

Implementation Method 1

an oxide is formed on the processing surface of the workpiece by anodic oxidation by passing a current through the workpiece as an anode

Methodology Applied

Scientific EffectAnodic oxidation: Oxidation

Implementation Method 2

The method involves using an alkaline electrolyte solution to control zeta potentials and reduce oxide film hardness

Methodology Applied

Scientific EffectZeta potential control: Electrostatics

Data Source

PatentUS20250096002A1Surface processing method

Publication Date: 2025.03.20 DENSO CORP

AI summary

A surface processing method for planarizing a processing surface of a workpiece includes the following procedures, treatments, or processes. With a wheel layer and the processing surface of the workpiece facing each other with an alkaline electrolyte solution between them, an oxide is formed on the processing surface of the workpiece by anodic oxidation by passing a current through the workpiece as an anode. The oxide formed on the processing surface by the anodic oxidation is removed by using the wheel layer.