CMP Polishing Pad Mapping for Stable Material Removal

Solution Overview

Problem

The performance of chemical mechanical polishing (CMP) tools deteriorates over time due to changes in polishing pad roughness and uniformity, leading to unstable material removal rates, hot spots, and increased defect rates in semiconductor wafer processing, resulting in scrapped dies and wafers.

Innovation Solution

A piezoelectric pad monitoring device is integrated into the CMP tool to non-destructively analyze the polishing pad's condition, generating signals for processor-based mapping of pad contacts, allowing for real-time adjustment of process parameters and maintenance, thereby extending the polishing pad's useful life and maintaining quality and repeatability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If polishing pad is used continuously for extended periods, then productivity increases, but polishing pad roughness and uniformity deteriorate leading to unstable material removal rates

Engineering Contradiction:

Improvepolishing pad usage durationVSAvoidmaterial removal rate stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs preliminary mapping of the polishing pad surface using piezoelectric sensors before actual polishing operations. This advance characterization of pad roughness and uniformity allows the system to predict and compensate for performance degradation, enabling extended pad usage while maintaining stable material removal rates through proactive rather than reactive adjustments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements continuous feedback by monitoring polishing pad condition through piezoelectric sensor arrays that map surface characteristics in real-time. This feedback loop enables dynamic adjustment of polishing parameters and alerts operators to pad degradation trends, allowing the system to maintain reliable performance throughout the pad's extended service life.

Inventive Principle:

Principle #23Feedback

2Loss of time

If polishing pad is used longer, then loss of time for pad replacement is reduced, but defect rates increase due to hot spots and non-uniform polishing

Engineering Contradiction:

Improvepad replacement frequencyVSAvoiddefect rate

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary mapping of the polishing pad surface using piezoelectric sensors before actual polishing operations. This advance characterization of pad roughness and uniformity allows the system to predict and compensate for performance degradation, enabling extended pad usage while maintaining stable material removal rates through proactive rather than reactive adjustments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements continuous feedback by monitoring polishing pad condition through piezoelectric sensor arrays that map surface characteristics in real-time. This feedback loop enables dynamic adjustment of polishing parameters and alerts operators to pad degradation trends, allowing the system to maintain reliable performance throughout the pad's extended service life.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If traditional polishing monitoring is used, then simple operation is maintained, but early detection of pad degradation is not possible leading to scrapped wafers

Engineering Contradiction:

Improveoperational simplicityVSAvoidpad condition detection capability

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The polishing system performs self-diagnosis by using piezoelectric sensors to automatically map and characterize pad surface conditions during operation. This self-monitoring capability enables early detection of degradation without requiring manual inspection or complex external measurement equipment, maintaining ease of operation while significantly improving measurement precision for pad condition assessment.

Inventive Principle:

Principle #25Self-service

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 enables prolonged use of polishing pads, reduces scrap, and minimizes defects by maintaining pad roughness and uniformity, ensuring consistent and reliable planarization operations.

Implementation Method 1

A piezoelectric pad monitoring device is integrated into the CMP tool to non-destructively analyze the polishing pad's condition, generating signals for processor-based mapping of pad contacts

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS20240391049A1Semiconductor processing tool and methods of operation

Publication Date: 2024.11.28 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A planarization tool is configured to monitor and analyze the condition of a polishing pad over the life of the polishing pad. A piezoelectric pad monitoring device may be mounted to a polishing head of the planarization tool in place of a semiconductor wafer. The piezoelectric pad monitoring device may be pressed against the polishing pad. When pressed against the polishing pad, the piezoelectric pad monitoring device may generate a signal based on a quantity of pad contacts, on the polishing pad, that are in contact with the piezoelectric pad monitoring device. The signal may be provided to a processor of the planarization tool so that the processor may generate, based on the signal, a map of the pad contacts on the polishing pad. The processor may use the map of the pad contacts to determine properties of the polishing pad such as roughness and/or uniformity, among other examples.