Charge Neutralizing Device for Wafer Surface Cleaning

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Solution Overview

Problem

Wafer charging during semiconductor manufacturing leads to circuit defects and yield reduction, particularly evident in 32 nm Mx levels with increasing dendrite defects, which existing CMP processes fail to effectively address.

Innovation Solution

A wafer processing system incorporating a charge neutralizing device, such as a pulsed DC ionizing bar, that measures wafer surface characteristics and neutralizes surface charges by ejecting positive and negative ions to counteract electrical charges, thereby preventing dendrite defects and improving yield.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If Chemical Mechanical Polishing (CMP) process is used to process wafer surface, then manufacturing precision is improved, but wafer charging occurs causing circuit defects and yield reduction

Engineering Contradiction:

Improvewafer surface planarityVSAvoidcircuit yield

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A charge neutralizing device is introduced as an intermediary component between the CMP process and the wafer inspection/processing stages. This device emits ions (positive and negative) that neutralize the surface charge accumulated on the wafer during CMP, preventing charge-related defects without interfering with the CMP polishing action itself

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful effect of wafer charging into a beneficial process by deliberately introducing a charge neutralization step. The harmful electrostatic charge buildup is transformed into an opportunity to apply controlled ion bombardment that neutralizes the charge and even improves surface cleanliness, turning a process defect into a potential quality enhancement

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Productivity

If wafer charging is allowed to occur during CMP, then production throughput is maintained, but dendrite defects increase and yield decreases

Engineering Contradiction:

Improveproduction throughputVSAvoiddendrite defects

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The charge neutralization is performed as a preliminary action either before the wafer enters the CMP process or immediately after CMP but before subsequent processing steps. By neutralizing the charge in advance, the system prevents the formation of dendrite defects in subsequent processing stages without requiring interruption to the production flow

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The charge neutralization process is designed to operate continuously alongside the CMP process, with the ion source running concurrently with wafer processing. This ensures that charge accumulation is continuously counteracted without interrupting the CMP throughput, maintaining continuous useful action on both fronts

Inventive Principle:

Principle #20Continuity of useful 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

The system effectively neutralizes wafer surface charges, reducing dendrite defects and enhancing production yield by smoothing charge peak regions and inhibiting charging, thus improving the reliability of semiconductor manufacturing processes.

Implementation Method 1

Methodology Applied

Scientific EffectIon ejection: Ion Beam

Implementation Method 2

A wafer processing system incorporating a charge neutralizing device, such as a pulsed DC ionizing bar

Methodology Applied

Scientific EffectElectrical discharge: Electric Arc

Data Source

PatentUS8336148B2System and method for cleaning a charging wafer surface

Publication Date: 2012.12.25 STMICROELECTRONICS INT NV

AI summary

A system and method for processing a wafer includes a charge neutralization system. The wafer processing system includes a wafer measuring device that can measure characteristics of a surface of the semiconductor wafer. One or more wafer processing stations perform a chemical mechanical polish (CMP) process on the wafer surface. A desica cleaning station can clean and dry the semiconductor wafer. The wafer processing system further includes a charge neutralizing device that can alter a surface charge of the wafer surface.