Megasonic Pad Conditioner for CMP Polishing Pad Cleaning

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Solution Overview

Problem

Conventional chemical mechanical polishing (CMP) processes face challenges in maintaining the stability of polishing pads due to pore damage and blockage by slurry abrasives and foreign substances, leading to reduced polishing rates and potential scratches on wafers.

Innovation Solution

The implementation of a CMP device and method utilizing megasonic waves for pad conditioning, employing a pad conditioner assembly with a quartz rod that generates megasonic vibrations to effectively remove slurry abrasives and foreign substances from the polishing pad surface, reducing damage and extending pad lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pad conditioner with diamond particles is used to remove slurry abrasives and foreign substances from the polishing pad, then the polishing pad surface can be conditioned, but the diamond particles may separate and damage or pollute the polishing pad surface

Engineering Contradiction:

Improvepolishing pad surface integrityVSAvoiddiamond particle contamination

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical abrasion system (diamond particles physically scraping the pad) with an acoustic field system (megasonic waves). The megasonic vibration energy transmitted through the polishing pad selectively removes slurry abrasives and foreign substances from pores without requiring contact from abrasive particles, thereby eliminating diamond particle contamination while maintaining pad conditioning effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces megasonic waves as an intermediary energy form to transfer momentum and energy to the polishing pad and embedded contaminants. Instead of directly contacting the pad with diamond particles, the megasonic field acts as a mediator that penetrates the pad structure and selectively dislodges contaminants through cavitation and mechanical vibration effects.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If diamond particles are used to clean the polishing pad pores, then slurry abrasives can be removed, but the function may be ineffective depending on the size of the pores

Engineering Contradiction:

Improvepore cleaning effectivenessVSAvoidpore size compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent employs megasonic vibration (high-frequency acoustic waves) to clean polishing pad pores of various sizes. The vibration energy propagates through the pad matrix and creates cavitation effects and mechanical stress that effectively dislodge slurry abrasives from pores regardless of their size, overcoming the limitation of diamond particle methods where particle size must be carefully matched to pore dimensions.

Inventive Principle:

Principle #18Mechanical vibration

3Productivity

If the polishing pad is used continuously for wafer polishing, then productivity is maintained, but pores become damaged and blocked by foreign substances

Engineering Contradiction:

Improvecontinuous polishing operationVSAvoidpolishing pad performance stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements periodic pad conditioning using megasonic waves during or between polishing operations. This periodic acoustic treatment cleans and rejuvenates the polishing pad surface, removing accumulated slurry abrasives and foreign substances from pores, thereby maintaining consistent polishing performance over extended operational periods and extending pad life.

Inventive Principle:

Principle #19Periodic action

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 enhances the effectiveness of pad conditioning, reducing the likelihood of pad damage and extending its lifespan, thereby improving the stability and efficiency of the CMP process without the need for diamond particles.

Implementation Method 1

A megasonic vibration may be simultaneously transferred to the pad conditioning liquid in order to remove foreign substances from a surface of the polishing pad

Methodology Applied

Scientific EffectMegasonic vibration: Ultrasonic Vibration

Implementation Method 2

A megasonic vibration may be simultaneously transferred to the pad conditioning liquid in order to remove foreign substances from a surface of the polishing pad

Methodology Applied

Scientific EffectMegasonic vibration: Ultrasonic Vibration

Data Source

PatentUS7559824B2Chemical mechanical polishing devices, pad conditioner assembly and polishing pad conditioning method thereof

Publication Date: 2009.07.14 SAMSUNG ELECTRONICS CO LTD

AI summary

Chemical mechanical polishing (CMP) devices, a pad conditioner assembly and a polishing pad conditioning method thereof are provided. The CMP device planarizes a wafer by rotating a carrier, which has a wafer mounted on a lower surface of the carrier, over a rotating polishing table while supplying a slurry onto a polishing pad attached to an upper surface of the rotating polishing table. The CMP device may include a pad conditioner assembly that conditions the polishing pad by supplying a pad conditioning liquid onto the polishing pad and simultaneously transferring a megasonic vibration to the pad conditioning liquid to remove foreign substances from a surface of the polishing pad.