Backside Wafer Polishing Layout Without Reversal or Edge Units

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Solution Overview

Problem

Conventional polishing units require reversing wafers to polish the back surface, leading to increased processing time, potential contamination from air impurities, and complex system construction due to the need for edge-polishing units and reversing machines.

Innovation Solution

A polishing apparatus with a substrate holder and polishing head configuration that allows for translational rotating motion, enabling the polishing of the entire back surface of a substrate, including the outermost area, without contact with the substrate holder, thus eliminating the need for reversing and edge-polishing units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If wafers are reversed to polish the back surface, then the back surface can be polished, but processing time increases and contamination risk increases

Engineering Contradiction:

Improveback surface polishing qualityVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

Instead of reversing the wafer to polish the back surface, the invention inverts the polishing approach by positioning the polishing head below the wafer and polishing the back surface while the wafer remains in its original orientation with the back surface facing downward, thus eliminating the time-consuming reversal step

Inventive Principle:

Principle #13The other way round (Inversion)

2Manufacturing precision

If wafers are reversed to polish the back surface, then the back surface can be polished, but contamination from air impurities occurs

Engineering Contradiction:

Improveback surface polishing qualityVSAvoidcontamination from air impurities

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The invention eliminates contamination risk by polishing the back surface without reversing the wafer, maintaining the back surface facing downward throughout the process, thus preventing exposure to air impurities that would occur during reversal and handling

Inventive Principle:

Principle #13The other way round (Inversion)

3Manufacturing precision

If conventional polishing units are used, then the polishing process can be performed, but the system construction becomes complex due to need for edge-polishing units

Engineering Contradiction:

Improvepolishing capabilityVSAvoidsystem construction

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The polishing head is designed to polish the entire back surface including the outermost area in a single operation, making the polishing unit universal and eliminating the need for separate edge-polishing units, thus simplifying the overall system construction

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If the polishing head is disposed inside the periphery of the wafer, then the polishing head will not contact the rotating chucks, but the outermost area of the wafer surface is not polished

Engineering Contradiction:

Improvepolishing process stabilityVSAvoidpolished area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

Instead of positioning the polishing head inside the wafer periphery and accepting the limitation of not polishing the outermost area, the invention inverts the approach by positioning the polishing head below the wafer to polish the back surface, including the outermost area, in the process

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention moves the polishing operation to another dimension by polishing the back surface of the wafer from below, rather than polishing the front surface from above, thus enabling coverage of the entire surface including outermost areas

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 reduces processing time, prevents contamination, simplifies the system construction, and enhances the efficiency of polishing the back surface of substrates by maintaining the back surface facing downward throughout the process.

Implementation Method 1

a polishing head configured to bring a polishing tape, having abrasive particles on one surface, into contact with a back surface of the substrate to polish the back surface

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS11865665B2Polishing apparatus

Publication Date: 2024.01.09 EBARA CORP

AI summary

A polishing apparatus which can efficiently polish an entirety of a back surface of a substrate, with the back surface facing downward, is disclosed. The polishing apparatus includes: a substrate holder configured to rotate the substrate; a polishing head configured to polish the back surface of the substrate; a tape advancing device; and a translational rotating mechanism configured to cause the polishing head to make a translational rotating motion. The substrate holder includes a plurality of rollers which are rotatable about their own axes. The plurality of rollers have substrate-holding surfaces capable of contacting a periphery of the substrate. The polishing head is disposed below the substrate-holding surfaces. The polishing head includes a polishing blade configured to press the polishing tape against the back surface of the substrate, and a pressing mechanism configured to push the polishing blade upward.