3D Printed Polishing Pad with Controlled Void Distribution

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Solution Overview

Problem

Conventional polishing pads face challenges in achieving uniform hardness distribution due to variations in porosity, leading to secondary scratches and non-uniform polishing rates across substrates, which are difficult to control with traditional machining methods.

Innovation Solution

3D printing is used to precisely control the distribution of voids and grooves in polishing pads, allowing for customized porosity and hardness profiles that compensate for differences in linear velocity and other sources of non-uniformity, enabling improved slurry transport and reduced fiber residue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional machining methods (milling, lathing) are used to create grooves in polishing pads, then grooves can be formed to transport slurry, but machining fibers remain on groove surfaces causing local resistance to slurry flow and non-uniform polishing rates

Engineering Contradiction:

Improvegroove formationVSAvoidgroove surface quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces conventional mechanical machining methods (milling, lathing) with a laser-based system. The laser ablates the polishing pad material to create grooves without mechanical contact, eliminating the generation of machining fibers that cause slurry flow resistance. This substitution of mechanical processing with optical/thermal processing resolves the contradiction between ease of manufacture and manufacturing precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Quantity of substance

If gas bubbles are injected into liquid precursor to create voids for porosity, then porosity can be introduced into polishing layers, but uniform local distribution of gas bubbles is difficult to achieve leading to variations in pad hardness

Engineering Contradiction:

ImproveporosityVSAvoiduniformity of void distribution

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

Instead of injecting gas bubbles into the liquid precursor (which creates uniformity problems), the patent extracts the porosity creation step and performs it after the pad is formed. The laser ablation process directly removes material to create voids with precise control over their size, shape, and distribution. This extraction of the porosity creation mechanism from the material formation process resolves the contradiction between introducing porosity and achieving uniform distribution.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses laser parameters (power, speed, pulse duration, wavelength) to precisely control the ablation process and resulting void characteristics. By changing these parameters, the system can create uniform void distributions with controlled size and spacing, eliminating the hardness variations that result from non-uniform gas bubble distribution in conventional methods.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If different materials are included in the polishing pad to introduce porosity, then porosity can be achieved, but differences in hardness at material interfaces cause secondary scratches on substrates

Engineering Contradiction:

ImproveporosityVSAvoidsecondary scratches

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating porosity through laser ablation at specific locations within the polishing pad rather than mixing different materials throughout. The laser can selectively remove material to create voids where needed while maintaining the uniformity of the base polymer matrix material. This eliminates the hardness mismatches at material interfaces that cause secondary scratches, while still achieving the desired porosity distribution for slurry transport.

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

This approach results in enhanced within-wafer uniformity and extended pad lifetime by ensuring consistent polishing rates and reducing secondary scratches, while allowing for tailored material properties and groove profiles that optimize slurry flow.

Implementation Method 1

3D printing allows better control of the distribution of pores in the polishing layer

Methodology Applied

Scientific Effect3D Printing: 3D Printing

Implementation Method 2

The polymer matrix precursor is solidified to form a solidified polymer matrix

Methodology Applied

Scientific EffectSolidification: Freezing

Data Source

PatentUS11007618B2Printing chemical mechanical polishing pad having window or controlled porosity

Publication Date: 2021.05.18 APPLIED MATERIALS INC

AI summary

A method of fabricating a polishing pad includes determining a desired distribution of voids to be introduced within a polymer matrix of a polishing layer of the polishing pad. Electronic control signals configured to be read by a 3D printer are generated which specify the locations where a polymer matrix precursor is to be deposited, and specify the locations of the desired distribution of voids where no material is to be deposited. A plurality of layers of the polymer matrix corresponding to the plurality of the first locations is successfully deposited with the 3D printer. Each layer of the plurality of layers of polymer matrix is deposited by ejecting a polymer matrix precursor from a nozzle. The polymer matrix precursor is solidified to form a solidified polymer matrix having the desired distribution of voids.