Electrostatic Abrasive Removal in Fixed Pad Polishing

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Solution Overview

Problem

Conventional fixed abrasive polishing processes in semiconductor manufacturing lead to wafer damage and low efficiency due to abrasive particles generated during the polishing process, which cannot be effectively prevented by existing methods.

Innovation Solution

A polishing method and device that utilize an electrode with a polarity opposite to the abrasive particles to adsorb silica or ceria particles in the polishing slurry, preventing them from scratching the wafer by using an alkaline solution to charge the particles negatively and the electrode positively, allowing for their removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If fixed abrasive polishing is used to improve polishing precision and abrasive utilization ratio, then polishing precision is improved, but abrasive particles are generated that cause wafer damage and scratches

Engineering Contradiction:

Improvepolishing precisionVSAvoidwafer damage and scratches

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the harmful abrasive particles from the polishing system by introducing an electrostatic removal mechanism. The electrode generates an electric field that attracts and removes abrasive particles from the polishing pad surface, preventing them from causing wafer damage while maintaining the fixed abrasive polishing process.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an electrode as an intermediary element between the polishing pad and the wafer. This electrode serves as a mediator that electrostatically attracts and removes abrasive particles, acting as a protective barrier that prevents direct contact between harmful particles and the wafer surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional CMP process is used, then polishing can be performed, but polishing slurry distributes randomly causing uneven density and low utilization ratio

Engineering Contradiction:

Improveslurry utilization ratioVSAvoidslurry distribution uniformity

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent replaces the conventional mechanical slurry distribution system with an electrostatic field-based system. Instead of relying on mechanical application and random distribution of slurry, the invention uses electrostatic attraction to precisely control slurry and abrasive particle positioning, achieving uniform distribution and high utilization ratio.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If deionized water rinsing is used to remove solid particles, then some particles are removed, but wafer damage cannot be absolutely prevented

Engineering Contradiction:

Improvewafer damage preventionVSAvoidwafer yield

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies preliminary action by removing abrasive particles before the polishing process completes. The electrode continuously attracts and removes particles during polishing, preventing them from accumulating and causing damage, rather than attempting to remove them after damage may have already occurred.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful abrasive particles into a beneficial controlled process. By using electrostatic attraction, the harmful particles are transformed into controllable elements that can be precisely removed and managed, turning a damaging factor into a controlled parameter.

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 solution effectively prevents wafer damage and improves polishing efficiency by removing abrasive particles, thereby increasing wafer yield and reducing the risk of scratches during the polishing process.

Implementation Method 1

adsorbing abrasive particles generated during the polishing process with an electrode, wherein the electrode has a polarity opposite to a polarity of charges of the abrasive particles

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 2

delivering a polishing slurry to the fixed abrasive polishing pad to polish the wafer... the polishing slurry includes a PH value ranging from about 10 to about 11... abrasive particles include silica particles or ceria particles

Methodology Applied

Scientific EffectIon charging: Ionisation

Data Source

PatentUS8758090B2Polishing method and polishing device

Publication Date: 2014.06.24 SEMICON MFG INT (SHANGHAI) CORP

AI summary

A polishing method includes: mounting a wafer on a fixed abrasive polishing pad located on a polishing platen; delivering a polishing slurry to the fixed abrasive polishing pad to polish the wafer; and adsorbing abrasive particles generated during the polishing process with an electrode. The electrode has a polarity opposite to a polarity of charges of the abrasive particles. A polishing device includes a polishing platen, a fixed abrasive polishing pad, a slurry pipeline and a polarity changer having an electrode. Therefore, the abrasive particles generated during the polishing process are removed, which prevents the wafer from being scratched, thereby increasing wafer yield and improving efficiency.