Wafer Cleaning Process Preventing Pattern Collapse

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The challenge in semiconductor device manufacturing is the pattern collapse of wafers with high aspect ratios during the cleaning process, which reduces production yield, and existing solutions either require specialized equipment or are not applicable to mass production due to poor throughput.

Innovation Solution

A cleaning process involving a water-repellent liquid chemical is used to form a water-repellent film on the surfaces of recessed portions of the wafer, reducing capillary force and preventing pattern collapse, by substituting the cleaning liquid with a water-repellent liquid chemical after cleaning, and drying the wafer, where the cleaning liquid contains 80% or more of a solvent with a boiling point between 55°C and 200°C, and the water-repellent liquid chemical is supplied at a temperature between 40°C and the boiling point of the liquid chemical.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cleaning with water or ammonia-mixed cleaning agent is used, then cleaning effectiveness is achieved, but pattern collapse occurs due to capillary force in high aspect ratio structures

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidpattern collapse

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical-chemical parameters of the cleaning liquid by using a solvent with a boiling point of 55-200°C instead of conventional water or ammonia-based cleaners. This parameter change allows effective cleaning while reducing capillary force that causes pattern collapse in high aspect ratio structures.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical cleaning action with a chemical substitution approach, where the cleaning liquid is substituted with a water-repellent liquid chemical after cleaning. This substitution reduces capillary force without requiring additional mechanical intervention, preventing pattern collapse.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If water-repellent liquid chemical is used to prevent pattern collapse, then pattern stability is improved, but process complexity increases due to additional substitution step

Engineering Contradiction:

Improvepattern collapseVSAvoidprocess complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the cleaning step with the water-repellent treatment by using a solvent that serves both cleaning and water-repellent functions. The cleaning liquid itself is formulated to provide water-repellent properties, eliminating the need for a separate substitution step and reducing process complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If standard cleaning device is used for mass production, then throughput is maintained, but pattern collapse occurs without specialized equipment

Engineering Contradiction:

ImprovethroughputVSAvoidpattern collapse

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition and physical properties of the cleaning liquid to a solvent with specific boiling point (55-200°C) and water-repellent characteristics. This parameter change allows standard cleaning equipment to achieve both high throughput and pattern collapse prevention without requiring specialized devices.

Inventive Principle:

Principle #35Parameter changes

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 process effectively reduces capillary force, preventing pattern collapse and improving production yield while maintaining economic and efficient cleaning without impairing throughput, allowing for the use of a standard cleaning device and facilitating mass production.

Implementation Method 1

a water-repellent film is formed at least on surfaces of recessed portions of the wafer by a water-repellent liquid chemical

Methodology Applied

Scientific EffectWater-repellent film formation: Hydrophobe

Implementation Method 2

reducing capillary force and preventing pattern collapse

Methodology Applied

Scientific EffectCapillary force reduction: Capillary Pressure

Implementation Method 3

substituting the cleaning liquid with a water-repellent liquid chemical after cleaning

Methodology Applied

Scientific EffectLiquid substitution: Liquid-Liquid Extraction

Implementation Method 4

drying the wafer

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS8828144B2Process for cleaning wafers

Publication Date: 2014.09.09 CENT GLASS CO LTD

AI summary

A process for cleaning a wafer having an uneven pattern at its surface. The process includes at least the steps of: cleaning the wafer with a cleaning liquid; substituting the cleaning liquid retained in recessed portions of the wafer with a water-repellent liquid chemical after cleaning; and drying the wafer, wherein the cleaning liquid contains 80 mass % or greater of a solvent having a boiling point of 55 to 200° C., and wherein the water-repellent liquid chemical supplied in the substitution step has a temperature of not lower than 40° C. and lower than a boiling point of the water-repellent liquid chemical thereby imparting water repellency at least to surfaces of the recessed portions.