CMP Polishing Pad Planarity Detection Using Movable Pin Array

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Solution Overview

Problem

The formation of a bubble between the polishing pad and the platen during the chemical mechanical polishing (CMP) process can lead to an uneven surface, increasing the risk of wafer cracking due to improper planarization, which existing methods fail to adequately address.

Innovation Solution

A detecting module with movable pins is used to monitor the surface flatness of the polishing pad before the CMP process, allowing for adjustment and ensuring the pad's planarity, thereby preventing wafer cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bubble forms between the polishing pad and platen during CMP process, then the polishing pad surface becomes uneven, but this leads to improper planarization and increased risk of wafer cracking

Engineering Contradiction:

Improvewafer cracking preventionVSAvoidpolishing pad planarity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The detecting module with multiple pins is used to detect the polishing pad surface condition before the CMP process begins. This preliminary detection identifies bubbles or unevenness in the polishing pad, allowing operators to address these issues before they can cause wafer cracking during polishing, thus preventing reliability problems before they occur

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The detecting module acts as an intermediary between the polishing pad condition and the CMP process. The module's pins contact the polishing pad surface and transfer information about surface irregularities (bubbles, unevenness) to the control system, enabling indirect monitoring of pad condition without interfering with the actual polishing process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If existing methods are used to monitor polishing pad condition, then the monitoring capability is insufficient, but this fails to prevent wafer cracking due to improper planarization

Engineering Contradiction:

ImproveCMP process reliabilityVSAvoidpolishing pad surface detection accuracy

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The detecting module divides the detection function into multiple independent pins arranged in an array. Each pin independently contacts the polishing pad surface at different locations, providing segmented measurement points that collectively map the overall surface condition. This segmentation enables more comprehensive detection of bubbles and unevenness compared to single-point detection methods

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces insufficient existing monitoring methods with a mechanical detection system using an array of pins that physically contact the polishing pad surface. This mechanical system provides direct, tangible measurement of surface irregularities, substituting for inadequate optical or non-contact methods that fail to adequately detect sub-surface bubbles

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10265828B2Method and system for monitoring polishing pad before CMP process

Publication Date: 2019.04.23 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A chemical mechanical polish (CMP) system is provided. The CMP system includes a platen rotatable about a rotation axis. The CMP system further includes a polishing pad positioned on the platen. The CMP system also includes a detecting module having a base portion and a number of pins positioned over the polishing pad. The pins are movable relative to the platen and have their bottom end in direct contact with the polishing pad to detect the planarity of the polishing pad.