Multistage Wafer Polishing with Intermediate Cleaning

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Solution Overview

Problem

Existing multistage polishing methods for wafers often result in defects such as scratches due to polishing debris and slurry interference between processes.

Innovation Solution

A multistage polishing apparatus and method that includes separate units for polishing the flat surface and peripheral portions of wafers, with a cleaning unit after each polishing process to remove debris and slurry, and a transport system to facilitate the cleaning and drying of the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multistage polishing is performed without intermediate cleaning, then productivity is improved by reducing process steps, but manufacturing precision deteriorates due to scratches from polishing debris

Engineering Contradiction:

Improvepolishing process efficiencyVSAvoidsubstrate surface quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

A cleaning unit is introduced as an intermediary component between the peripheral-portion polishing unit and the CMP unit. This cleaning unit removes polishing debris from the substrate before it enters the next polishing stage, preventing scratches while maintaining continuous processing. The cleaning unit acts as a mediator that resolves the conflict between maintaining productivity and ensuring manufacturing precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cleaning unit performs preliminary cleaning action before the substrate enters the CMP unit. By removing polishing debris in advance, the system prevents contamination and scratches during subsequent polishing operations, ensuring high manufacturing precision without interrupting the overall multistage polishing workflow.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If polishing debris is not removed between stages, then device complexity is reduced by eliminating cleaning units, but reliability deteriorates due to defects in subsequent polishing processes

Engineering Contradiction:

Improveapparatus structureVSAvoidpolishing process consistency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The cleaning unit serves as a necessary intermediary that ensures reliable operation of subsequent polishing stages. By removing polishing debris between stages, it prevents defects and maintains consistent polishing quality, making the additional complexity worthwhile for achieving reliable results.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cleaning unit provides self-service functionality within the polishing apparatus, automatically cleaning the substrate between polishing stages without requiring external intervention. This integrated self-cleaning capability maintains reliability while minimizing the need for additional complex external cleaning systems.

Inventive Principle:

Principle #25Self-service

3Device complexity

If a single cleaning unit is used for both polishing stages, then device complexity is reduced, but manufacturing precision deteriorates due to cross-contamination between polishing types

Engineering Contradiction:

Improvecleaning system configurationVSAvoidsubstrate cleanliness

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The cleaning function is segmented into separate cleaning units corresponding to each polishing stage. The first cleaning unit cleans after peripheral-portion polishing, and the second cleaning unit cleans after CMP. This segmentation prevents cross-contamination between different polishing types and maintains high manufacturing precision for each stage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each cleaning unit is specifically designed and positioned to address the cleaning needs of its corresponding polishing stage. The first cleaning unit handles debris from peripheral polishing, while the second cleaning unit handles slurry from CMP processing. This localized cleaning approach ensures optimal cleanliness quality for each specific polishing process.

Inventive Principle:

Principle #3Local quality

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

Prevents defects like scratches by ensuring thorough cleaning after each polishing process, enhancing the quality of subsequent polishing stages.

Implementation Method 1

a cleaning unit configured to clean the polished substrate

Methodology Applied

Scientific EffectCleaning:

Implementation Method 2

a drying unit configured to dry the substrate that has been cleaned in the cleaning unit

Methodology Applied

Scientific EffectDrying:

Data Source

PatentUS9144881B2Polishing apparatus and polishing method

Publication Date: 2015.09.29 EBARA CORP

AI summary

A polishing apparatus includes a peripheral-portion polishing unit configured to polish a peripheral portion of the substrate, a CMP unit configured to polish a flat surface of the substrate W, a cleaning unit configured to clean the polished substrate, a transport system configured to transport the substrate. The transport system transports the substrate that has been polished in one of the peripheral-portion polishing unit and the CMP unit to the cleaning unit, and transports the substrate that has been cleaned in the cleaning unit to the other of the peripheral-portion polishing unit and the CMP unit.