Polishing Surface Shaping to Compensate for Non-Flat Chuck Tables

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Solution Overview

Problem

Existing polishing apparatuses fail to uniformly polish workpieces with in-plane thickness variations, leading to residual thickness variations in the polished workpieces due to irregular polishing pressure caused by non-flat chuck table holding surfaces.

Innovation Solution

A processing apparatus with a chuck table rotary actuator, polishing pad rotary actuator, and shaping mechanisms that measure and shape the polishing surface to be complementary to the chuck table's holding surface, ensuring uniform polishing pressure and reducing thickness variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the chuck table holding surface is non-flat, then the device can be manufactured with simpler structure, but the polishing pressure becomes irregular causing thickness variations

Engineering Contradiction:

Improvechuck table structureVSAvoidthickness uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The polishing pad surface is shaped with local variations corresponding to the chuck table's non-flat holding surface. By making the polishing pad's surface profile complementary to the chuck table's shape, uniform polishing pressure is achieved across the workpiece area, resolving the contradiction between simple chuck table structure and uniform polishing pressure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of making the chuck table flat (symmetric solution), the invention accepts the non-flat (asymmetric) chuck table structure and creates a corresponding asymmetric polishing pad surface that compensates for the irregularity, thereby achieving uniform polishing pressure despite the asymmetric chuck table geometry.

Inventive Principle:

Principle #4Asymmetry

2Ease of operation

If the polishing pad is pressed against the workpiece with constant force, then the polishing process is simple to control, but thickness variations remain due to non-flat holding surface

Engineering Contradiction:

Improvepolishing controlVSAvoidthickness uniformity

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The polishing pad surface is designed with local quality variations that match the chuck table's shape. This allows the polishing pad to maintain constant contact pressure with the workpiece across different regions, achieving uniform thickness removal while keeping the control system simple.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If the chuck table holding surface is made flat, then uniform polishing pressure is achieved, but the device complexity increases

Engineering Contradiction:

Improvethickness uniformityVSAvoidchuck table structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of modifying the chuck table to be flat (conventional approach), the invention inverts the solution by keeping the chuck table as-is and modifying the polishing pad surface to be complementary to the chuck table's shape. This achieves the same effect of uniform polishing pressure with less device complexity.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The polishing pad is designed with local surface variations that correspond to the chuck table's geometry. This localized adaptation allows the system to maintain uniform polishing pressure without requiring a complex flat chuck table structure.

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

The apparatus effectively reduces thickness variations in polished workpieces by shaping the polishing surface to match the chuck table's shape, ensuring uniform polishing pressure and improved surface quality.

Implementation Method 1

a shaping mechanism for shaping the polishing surface while in contact therewith

Methodology Applied

Scientific EffectMechanical contact shaping:

Implementation Method 2

the polishing pad is moved toward the workpiece, bringing its polishing surface into abrasive contact with a surface to be polished

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS20250262710A1Processing apparatus and polishing surface shaping method

Publication Date: 2025.08.21 DISCO CORP

AI summary

A processing apparatus includes a chuck table having a holding surface for holding a workpiece thereon, a chuck table rotary actuator for rotating the chuck table, a polishing unit on which a polishing pad having a polishing surface for polishing the workpiece is mounted, a polishing pad rotary actuator for rotating the polishing pad, a polishing moving mechanism for moving the chuck table and the polishing pad relatively to each other, a shape measuring instrument for measuring a shape of the holding surface, a shaping mechanism for shaping the polishing surface while in contact therewith, a shaping moving mechanism for moving the polishing pad and the shaping mechanism relatively to each other, and a controller for making the polishing surface complementary in shape to the holding surface.