Cylindrical Roller for Location-Specific Wafer Polishing

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Solution Overview

Problem

Chemical mechanical polishing (CMP) processes face challenges in achieving uniformity, particularly at the substrate edges due to 'check mark' non-uniformities and asymmetries, which existing technologies struggle to correct effectively, leading to stringent film thickness non-uniformity thresholds that are difficult to meet.

Innovation Solution

A location-specific polishing method using a cylindrical roller with a polishing pad affixed to its surface, where the roller's parameters (diameter, pad grit) are tailored to the substrate shape and thickness profile, allowing for precise material removal by optimizing substrate and roller rotational speeds, and pressure distribution to compensate for angular asymmetries and edge non-uniformities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional CMP process with a rotating polishing pad is used, then the substrate surface can be planarized, but within-wafer and wafer-to-wafer non-uniformity occur due to check mark patterns and edge non-uniformities

Engineering Contradiction:

Improvefilm thickness uniformityVSAvoidcheck mark non-uniformity and edge non-uniformity

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent inverts the conventional CMP approach by using a stationary substrate instead of a rotating polishing pad. The substrate is held stationary on the carrier head while polishing material is delivered to specific locations through a programmable array of nozzles, reversing the traditional motion-based polishing mechanism and enabling location-specific material removal without rotational non-uniformities

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies local quality by using a programmable array of nozzles that can independently control polishing material delivery to different locations on the substrate. This allows different regions of the substrate to receive customized polishing treatment, correcting local non-uniformities such as check mark patterns and edge effects while maintaining overall planarization

Inventive Principle:

Principle #3Local quality

2Stress or pressure

If pressure is applied through the wafer backside in conventional CMP, then the substrate can be pressed against the polishing pad, but location specificity is reduced and substrate flex increases

Engineering Contradiction:

Improvepressure distributionVSAvoidlocation specificity and substrate stability

Core Design Contradiction:

Stress or pressureVSManufacturing precision

Solution Approach 1:

The patent introduces an intermediary mechanism - a programmable array of nozzles that deliver polishing material and apply pressure locally at the substrate surface. This intermediary system replaces direct backside pressure application, enabling precise location-specific polishing while minimizing substrate flex and maintaining positional accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent substitutes the conventional mechanical pressure application system (carrier head pressing uniformly on substrate backside) with a material-delivery-based system where polishing slurry is programmably dispensed to specific locations. This replacement of mechanical pressure with controlled material delivery achieves location specificity without inducing substrate flex

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If a polishing method that removes material from the entire front face is used, then non-uniform regions can be corrected, but material is unnecessarily removed from already planar areas

Engineering Contradiction:

Improvenon-uniformity correctionVSAvoidmaterial removal from planar regions

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs partial action by activating only the specific nozzles corresponding to regions that require polishing correction. Instead of applying polishing material uniformly across the entire substrate, the system selectively targets only the non-uniform areas, thereby avoiding unnecessary material removal from already planar regions

Inventive Principle:

Principle #16Partial or excessive action

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 reduces within-wafer and wafer-to-wafer non-uniformity, enables precise correction of edge thickness profiles, and increases location specificity, thereby improving polishing efficiency and throughput while maintaining substrate flexibility and reducing maintenance costs.

Implementation Method 1

Chemical mechanical polishing (CMP) is one accepted method of planarization

Methodology Applied

Scientific EffectChemical mechanical polishing:

Implementation Method 2

A polishing liquid, such as slurry with abrasive particles, is supplied to the surface of the polishing pad during material removal

Methodology Applied

Scientific EffectChemical mechanical polishing:

Data Source

PatentUS12194591B2Roller for location-specific wafer polishing

Publication Date: 2025.01.14 APPLIED MATERIALS INC

AI summary

A polishing apparatus includes a support configured to receive and hold a substrate in a plane, a polishing pad affixed to a cylindrical surface of a rotary drum, a first actuator to rotate the drum about a first axis parallel to the plane, a second actuator to bring the polishing pad on the rotary drum into contact with the substrate, and a port for dispensing a polishing liquid to an interface between the polishing pad and the substrate.