CMP Carrier Head Membrane Assembly for Uniform Pressure Distribution

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Solution Overview

Problem

Existing chemical-mechanical polishing (CMP) apparatuses face issues with uneven pressure distribution, leading to reduced polishing efficiency and increased wafer damage due to sharp inflection points and non-uniform pressure application, resulting in reduced semiconductor production yield and frequent membrane replacement.

Innovation Solution

A dual-layer membrane assembly with a dividing membrane and a main membrane, where the dividing membrane receives air pressure and applies it to the main membrane, and a circular ring with an inclined surface directs pressure to the wafer edge, ensuring uniform pressure distribution and secure contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a ring-shaped membrane supporting stem is used to divide the membrane into inner and outer chambers, then multiple-region division polishing can be achieved, but a sharp circular inflection point is formed causing unstable pressure distribution and reduced polishing speed at the boundary

Engineering Contradiction:

Improvemultiple-region division polishing capabilityVSAvoidpressure uniformity and polishing quality at chamber boundary

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The membrane is divided into multiple independent chambers (first, second, and third chambers) separated by partition walls. This segmentation allows different pressure levels to be applied to different regions of the wafer, enabling multiple-region division polishing while avoiding the inflection point problem by using flat partition walls instead of ring-shaped supporting stems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different pressure levels are applied to different chambers to achieve localized polishing control. The first chamber applies a first pressure level, while the second and third chambers apply a second pressure level, allowing optimized polishing for different wafer regions (center vs. edge) without creating sharp pressure transitions.

Inventive Principle:

Principle #3Local quality

2Reliability

If indirect suctioning method is used to fix the wafer on the membrane, then the wafer can be held during polishing, but the suctioning error causes wafer separation and damage

Engineering Contradiction:

Improvewafer holding capabilityVSAvoidwafer separation and damage due to suctioning error

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A separate suction plate is introduced as an intermediary component between the carrier head and the wafer. The suction plate directly contacts the wafer bottom surface and applies vacuum suction, while the membrane contacts the wafer polishing surface. This intermediary structure eliminates the suctioning error problem by decoupling the holding function from the polishing function.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If pressure is applied uniformly across the membrane, then the membrane structure is simple, but the edge region of the wafer is not sufficiently polished reducing production yield

Engineering Contradiction:

Improvemembrane structure simplicityVSAvoidproduction yield due to insufficient edge polishing

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The membrane structure is designed with different chamber configurations to apply different pressure levels to different regions. The first chamber applies higher pressure for effective edge polishing, while the second and third chambers apply lower pressure for center region polishing, optimizing both edge and center polishing quality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The membrane is segmented into multiple chambers with different pressure characteristics. This segmentation allows the system to achieve non-uniform pressure distribution (higher at edges, lower at center) without requiring a complex single-chamber design, balancing structural simplicity with polishing effectiveness.

Inventive Principle:

Principle #1Segmentation

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 solution enhances polishing efficiency by maintaining stable pressure across the wafer surface, reducing wafer damage, and allowing for easy membrane replacement, thereby improving production yield and extending the lifespan of the carrier head.

Implementation Method 1

a circular ring disposed at an edge portion of the main membrane and receiving an air pressure to downwardly apply the air pressure to the main membrane

Methodology Applied

Scientific EffectAir pressure: Pressure Increase

Implementation Method 2

a carrier head holds or receives a wafer by directly and indirectly vacuum-suctioning the wafer

Methodology Applied

Scientific EffectVacuum suctioning: Suction

Data Source

PatentUS8939817B2Membrane assembly and carrier head having the membrane assembly

Publication Date: 2015.01.27 KC LTD

AI summary

Provided is a membrane assembly of a carrier head in a chemical-mechanical polishing apparatus. The membrane assembly includes a main membrane and a circular ring. The main membrane has a wafer contacting surface in contact with a wafer while a chemical-mechanical polishing process is being performed. The circular ring is disposed at an edge portion of the main membrane and receives an air pressure to downwardly apply the air pressure to the main membrane at the edge portion.