Polishing Pad Window Molding for CMP Endpoint Transmittance

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Solution Overview

Problem

Conventional polishing pad windows lack sufficient transmittance for optical beams, making it difficult to accurately detect the polishing end point in the CMP process.

Innovation Solution

A method involving mixing a polyurethane prepolymer with a curing agent at controlled temperatures, injecting the mixture into a heated mold, and processing the cured product to achieve a window with improved transmittance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a conventional polishing pad window is used, then the structure is simple and manufacturing is easy, but the transmittance for optical beam passage is insufficient

Engineering Contradiction:

ImprovetransmittanceVSAvoidmanufacturing complexity

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by controlling the temperature of the polyurethane prepolymer (50-100°C) and the mold (30-100°C) during the injection molding process. These temperature parameters directly affect the transmittance of the resulting window, with higher temperatures within this range producing windows with transmittance of 5% or more at 1.9mm thickness, thereby resolving the contradiction between maintaining ease of manufacture and improving optical transmittance.

Inventive Principle:

Principle #35Parameter changes

2Strength

If the window thickness is increased to improve structural strength, then the mechanical strength is improved, but the transmittance for optical beam detection is reduced

Engineering Contradiction:

Improvestructural strengthVSAvoidtransmittance

Core Design Contradiction:

StrengthVSIllumination intensity

Solution Approach 1:

The patent resolves this contradiction by changing the material parameters through temperature-controlled injection molding. By optimizing the prepolymer temperature (50-100°C) and mold temperature (30-100°C), the process produces windows with enhanced optical properties where transmittance reaches 5% or more at 1.9mm thickness, achieving a favorable balance between structural strength and optical transmittance that would not be possible with conventional manufacturing methods.

Inventive Principle:

Principle #35Parameter changes

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 method enables the production of a polishing pad window with transmittance of 5% or more, allowing accurate and reliable detection of the polishing end point.

Implementation Method 1

mixing a curing agent with a polyurethane prepolymer having a temperature of 50° C. or higher to less than 100° C. to prepare a mixture

Methodology Applied

Scientific EffectCuring reaction: Chemical Bonding

Implementation Method 2

injecting the mixture into a mold heated to a temperature of 30° C. or higher to less than 100° C.

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12570029B2Method for manufacturing polishing pad window, and polishing pad window manufactured thereby

Publication Date: 2026.03.10 KPX ELECTROCHEM CO LTD

AI summary

A method for manufacturing a window for a polishing pad is disclosed. The method includes: a) mixing a curing agent with a polyurethane prepolymer having a temperature of 50° C. or higher to less than 100° C. to prepare a mixture; b) injecting the mixture into a mold heated to a temperature of 30° C. or higher to less than 100° C. to a thickness of 5 mm or less; c) demolding a polyurethane cured product from the mold; and d) processing the polyurethane cured product to a thickness of the window of the polishing pad. A polishing pad including the window is also disclosed.