CMP Pad Cooling Control for Low-Temperature Metal Polishing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Chemical mechanical polishing (CMP) processes face challenges in temperature control, leading to variations in polishing rate, uniformity, dishing, erosion, and corrosion, which affect the quality of polished wafers and the lifespan of polishing pads.

Innovation Solution

A CMP system that includes a platen with a polishing pad, a coolant source, and a controller to direct coolant onto the polishing pad, using liquid or gas coolants like nitrogen or carbon dioxide, and a vortex tube to control temperature during different stages of the polishing process, such as metal clearing and over-polishing, to maintain optimal pad asperity and reduce galvanic reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If temperature control is not implemented during CMP, then the polishing process is simpler, but temperature-dependent issues like dishing, erosion, and corrosion increase

Engineering Contradiction:

Improvetemperature control systemVSAvoidpolishing uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by controlling the temperature of the polishing pad surface through coolant delivery. The system changes the thermal parameter of the polishing interface to minimize temperature-dependent issues such as dishing, erosion, and corrosion, thereby improving polishing uniformity and manufacturing precision

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses coolant as an intermediary substance to transfer heat away from the polishing pad surface. The coolant acts as a mediator between the polishing interface and the environment, absorbing excess heat and maintaining optimal temperature conditions for precise polishing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If coolant is delivered continuously, then temperature control is better, but polishing rate and productivity decrease

Engineering Contradiction:

Improvepolishing pad temperatureVSAvoidpolishing rate

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The patent implements periodic action by delivering coolant only during selected steps of the polishing operation, such as metal clearing, over-polishing, or conditioning steps. This intermittent cooling approach maintains temperature control when needed while preserving polishing rate during bulk removal phases, thus balancing temperature management with productivity

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies dynamics by making the coolant delivery dynamic and adaptive to the polishing process stage. The system adjusts coolant delivery based on real-time process requirements, increasing cooling during critical steps and reducing or stopping it during bulk polishing to optimize both temperature control and polishing efficiency

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If temperature varies spatially on the polishing pad, then the polishing process is more flexible, but polishing uniformity and wafer-to-wafer consistency deteriorate

Engineering Contradiction:

Improvepolishing process flexibilityVSAvoidwafer-to-wafer uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by delivering coolant to specific locations on the polishing pad surface through strategically positioned nozzles. This localized cooling approach addresses temperature variations at critical spots while maintaining overall process flexibility, ensuring uniform polishing results across different wafers

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 solution improves polishing uniformity, extends pad lifetime, reduces defects, and enhances wafer-to-wafer uniformity by tightly controlling the polishing pad temperature, thereby minimizing dishing and corrosion.

Implementation Method 1

A CMP system that includes a platen with a polishing pad, a coolant source, and a controller to direct coolant onto the polishing pad

Methodology Applied

Scientific EffectHeat absorption: Heat Sink

Implementation Method 2

The source of gas coolant medium can be connected to a vortex tube configured to direct a cold stream of gas onto the polishing pad

Methodology Applied

Scientific EffectVortex tube effect: Ranque-Hilsch Effect

Data Source

PatentUS11897079B2Low-temperature metal CMP for minimizing dishing and corrosion, and improving pad asperity

Publication Date: 2024.02.13 APPLIED MATERIALS INC

AI summary

A chemical mechanical polishing system includes a platen to support a polishing pad having a polishing surface, a source of coolant, a dispenser having one or more apertures suspended over the platen to direct coolant from the source of coolant onto the polishing surface of the polishing pad; and a controller coupled to the source of coolant and configured to cause the source of coolant to deliver the coolant through the nozzles onto the polishing surface during a selected step of a polishing operation.