CMP Retainer Ring Groove Design for Slurry Drainage

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Solution Overview

Problem

Chemical mechanical polishing (CMP) retainer rings in semiconductor manufacturing are prone to contamination from slurry, leading to surface scratches and defects during the polishing process.

Innovation Solution

The design of retainer rings with a base portion having slurry inflowing portions featuring groove shapes and minute grooves, where the width and depth of the grooves are optimized to prevent slurry attachment, using engineering plastics like PPS, and manufacturing methods involving mechanical processing or photolithography to create these features.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional retainer ring without groove structures is used, then the structure is simple and easy to manufacture, but slurry contamination occurs leading to surface scratches and defects

Engineering Contradiction:

Improveprevention of slurry contaminationVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The retainer ring surface is segmented into multiple groove structures (radial grooves, circumferential grooves, and diagonal grooves) that divide the slurry flow path. This segmentation prevents slurry from accumulating and adhering to the retainer ring surface, effectively reducing contamination while maintaining a manageable structural complexity through systematic groove patterning.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The retainer ring incorporates groove structures that create a porous-like surface topology. These grooves allow slurry to pass through and drain away from the retainer ring surface rather than adhering to it, functioning similarly to porous materials that prevent liquid accumulation while maintaining structural integrity.

Inventive Principle:

Principle #31Porous materials

2Reliability

If groove structures are added to the retainer ring to prevent slurry attachment, then contamination is reduced, but manufacturing complexity increases

Engineering Contradiction:

Improveprevention of slurry contaminationVSAvoidmanufacturing ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces complex mechanical groove formation processes with chemical etching or mold-integrated groove formation. During molding, groove patterns are directly incorporated into the retainer ring mold cavities, allowing mass production of grooved retainer rings without additional mechanical machining steps, thus maintaining ease of manufacture while achieving contamination prevention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The groove dimensions (width, depth, spacing) are optimized within specific parameter ranges to achieve effective slurry drainage. By standardizing these parameters during mold design, the manufacturing process becomes more predictable and easier to control, reducing the impact of added complexity on ease of manufacture.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If the retainer ring surface is made smooth and flat, then manufacturing is easier, but slurry adheres to the surface causing scratches on substrates

Engineering Contradiction:

Improvemanufacturing easeVSAvoidsurface scratches from slurry

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

Instead of making the retainer ring surface smooth to facilitate manufacture, the invention inverts the approach by creating a grooved surface that actively directs slurry away from the substrate contact area. The grooves provide drainage pathways that prevent slurry from adhering to the retainer ring and being transferred to the substrate, thereby eliminating the harmful scratching effect while maintaining manufacturing feasibility through mold-integrated groove formation.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention converts the potentially harmful slurry adhesion issue into a beneficial drainage function. The groove structures, which add surface complexity, create controlled pathways that guide slurry flow away from critical areas, transforming what would be a contamination problem into an active cleaning and protection mechanism for the substrate.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS8858302B2Retainer rings of chemical mechanical polishing apparatus and methods of manufacturing the same

Publication Date: 2014.10.14 SAMSUNG ELECTRONICS CO LTD

AI summary

A retainer ring of a chemical mechanical polishing apparatus includes a base portion having a ring shape, the base portion including a pressurizing surface and a combining surface opposite the pressurizing surface, slurry inflowing portions on the pressurizing surface of the base portion, the slurry inflowing portions having groove shapes, and minute grooves at least on a surface portion of the slurry inflowing portions.