A Comparison of Wet Manual Cleaning Processes to Carbon

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A Comparison of Wet Manual Cleaning Processes to Carbon

Transcript Of A Comparison of Wet Manual Cleaning Processes to Carbon

A Comparison of Wet Manual Cleaning Processes to Carbon Dioxide Cleaning Processes in the Semiconductor Industry
By: Justin M. Tourdot A Research Paper Submitted in Partial Fulfillment of the Requirements
for the Masters of Science Degree in Risk Control
Approved: Three Semester Credits
The Graduate College University of Wisconsin Stout
May, 2001

The Graduate College University of Wisconsin Stout
Menomonie, WI 54751

Tourdot

ABSTRACT

Justin

M.

(Last Name)

(First)

(Initial)

A Comparison of Wet Manual Cleaning Processes to Carbon Dioxide Processes in the

Semiconductor Industry.

(Title)

Risk Control (Major)

John H. Olson Ph.D (Research Advisor)

May, 2001 30

(Date)

(Pages)

American Psychological Association

(Format Style)

The purpose of the study was to analyze the risk exposures and costs involved in cleaning parts, equipment, and tooling in the semiconductor industry using wet manual processes and compare carbon dioxide as an alternative cleaning process.
The research focuses on wet manual processes currently used by semiconductor manufacturers to clean parts, tools, and equipment and carbon dioxide cleaning processes as an alternative to these processes.
A current analysis of the chemicals used in the wet manual processes and the risks they pose to an organization compared to the risks associated with carbon dioxide processes. The research concludes that carbon dioxide blast cleaning processes reduce or eliminate employee health exposures, wastewater discharge, hazardous waste treatment costs, reduced environmental reporting requirements and liability issues, and clean at or better than current wet manual processes.

TABLE OF CONTENTS
Abstract………………………………………………………………………. i Acknowledgement……………………………………………………………. ii Table of Contents…………………………………………………………….. iii Chapter 1: Statement of the Problem……………………………………. 1
Purpose of the Study…………………………………………………. 1 Goals of the Study…………………………………………………… 2 Definition of Terms…………………………………………………. 4 Chapter II : Review of Literature………………………………………... 5 Introduction…………………………………………………………. 5 Wet Manual Cleaning Process……………………………………… 5 CO2 Blast Cleaning Process…………………………………………. 9 Supercritical CO2 Cleaning Process………………………………… 12 Chapter III : Methodology……………………………………………….. 20 Chapter IV – The Study…………………………………………………… 22 Introduction…………………………………………………………. 22 Process Assessments……..………………………………………….. 22 Financial Data……………………………………………………….. 24 Chapter V – Conclusions and Recommendations……………………….. 26
Conclusions…………………………………………………………………. 26 Recommendations…………………………………………………………… 28 Refererences…………………………………………………………………. 29
i

CHAPTER 1 STATEMENT OF THE PROBLEM
INTRODUCTION
Cleaning parts, machines and equipment is a function of the production process that focuses on removing contaminants from a surface. These surfaces need to be cleaned to maintain quality, productivity, and overall efficiency of the production process.
The semiconductor industry has traditionally cleaned parts using acids, chlorinated, fluorinated, and other halogenated solvents to remove contaminates because of their stability and ease of drying (SEMARNAP, 1996). Environmental regulations, adverse health effects and costs of disposing of these chemicals has led industries to search for technologies that can reduce or eliminate these issues.
Carbon dioxide blasting processes are an alternative to the traditional processes of cleaning parts, tools, and equipment.
PURPOSE OF THE STUDY
The purpose of the study is to analyze the risk exposures and costs involved in cleaning parts, equipment, and tooling in the semiconductor industry using wet manual processes and compare carbon dioxide as an alternative cleaning process.

GOALS OF THE STUDY
The goals of the study were to: 1. Analyze wet manual cleaning processes and the risks exposures that these
processes pose to an organization, specifically health exposures to employees, environmental impacts, facility exposures, and liability issues. 2. Examine using carbon dioxide as an alternative method to cleaning parts that reduce or eliminate the above-mentioned exposures. 3. Provide financial justification for the implementation of an alternative system to clean parts, tools, and equipment used in the manufacturing process.
BACKGROUND & SIGNIFICANCE
Dry cleaning processes are becoming the preferred method for cleaning parts and equipment in the semiconductor industry. The ultimate dream for the semiconductor industry is all dry cleaning processes (Van Zant, 97). The estimated global market for semiconductor equipment parts cleaning, based on 750 fabs worldwide will exceed one billion dollars annually (PRNewswire, 2000). This is a significant cost in the semiconductor manufacturing process. Reasons for utilizing dry cleaning processes include a significant reduction in hazardous waste accumulation and treatment costs, reduced employee health exposures and faster part cleaning times. There is evidence that significant savings can be achieved by the conversion to one of these alternative cleaning systems. Carbon dioxide cleaning processes are examples of these dry process methods.
Solvents and chemicals in use for parts cleaning in the semiconductor industry include methylene chloride, methyl ethylketone (MEK), glycol mixtures, hydrofluoric

and sulfuric acids, tolulene, xylene, and alcohols. These chemicals present health, facility, and process quality risks to a semiconductor manufacturer. Dry cleaning processes seek to reduce or eliminate these risks as a tool to minimize losses and increase profitability as part of the semiconductor manufacturing process.
The hidden costs associated with wet cleaning processes include improved employee health and safety, lower maintenance, efficient chemical and water usage, improved productivity, reduced regulatory costs, lower future liability.
LIMITATIONS OF THE STUDY
There is not a significant amount of research published on the implementation of carbon dioxide cleaning processes. The carbon dioxide blast cleaning process and supercritical carbon dioxide cleaning processes are relatively new to the semiconductor industry.

DEFINITION OF TERMS
Dry Cleaning Processes- Processes that do not use water as part of their cleaning medium. Enthalpy- The sum of the internal energy of a body and the product of its volume multiplied by the pressure. Glovebox- an enclosure designed to contain the gases and particulates being removed from the object during cleaning. Lipid- any of various substances that are soluble in nonpolar organic solvents that with protein and carbohydrates constitute the principal structural components of living cells. Semiconductor fabrication- The process of manufacturing semiconductor devices often referred to as mircoelectronic circuits, integrated circuits, components, microchips, or chips. Soluble- capable of being loosened or dissolved Sputum- expectorated matter made up of saliva and often discharges from the respiratory passages. Sublimation- To pass directly from the solid form to a vapor form Substrate- Underlying surface of which a layer is formed Wet cleaning processes- Those aqueous, semi-aqueous, and chemical processes using acids, solvents, surfactants, alkaline cleaners, builders, dispersants, corrosion inhibitors, chelating agents and defoamers to clean parts, tools, and equipment. Carpal Tunnel Syndrome- An affliction caused by compression of the median nerve in the carpal tunnel. Often associated with tingling, pain, or numbness in the thumb and first three fingers.

CHAPTER 2 REVIEW OF LITERATURE
INTRODUCTION
Included in this chapter is a review of wet manual cleaning systems and two types of carbon dioxide cleaning systems; carbon dioxide blast cleaning and supercritical carbon dioxide cleaning (SCCO2). The review is used to gain an understanding of the technical processes and risks each process pose to an organization.
Cleaning parts, tools and equipment is an essential function of a semiconductor manufacturer. Aqueous, CO2 blast, and supercritical CO2 cleaning processes have advantages in relation to the quality of cleaning, the adverse effects on human health, the environmental impacts, and facility exposures. Ultimately these adverse effects can impact an organizations ability to operate efficiently.
WET MANUAL CLEANING PROCESSES
Wet manual cleaning processes use solvents, acids, and other chemicals to remove contaminants from the substrate of the object to be cleaned. Mechanical agitation such as ultrasonic or scrubbing with an abrasive material to remove the contaminant is often necessary. Monitoring of the chemistry to a specific concentration is sometimes necessary to maintain the cleaning effectiveness of the solution.
Acids, solvents, alkaline cleaners, builders, surfactants, dispersants, corrosion inhibitors, chelating agents and defoamers are some of the following chemical components that can be added to the water to create the cleaning solution. Solvents and

acids will be the primary focus of this review due to their toxicity and environmental issues.
Hydrochloric, sulfuric, chromic, carboxylic, and nitric acids are commonly used acids in aqueous cleaning solutions. These acids are effective in the removal of metal oxides and organic metallics.
Organic solvents are used to dissolve and disperse fats, oils, waxes, pigments, varnishes, rubber, and many other contaminants. Organic solvents are classified into chemical groups dependent upon their chemical configuration and the absence or presence of functional groups. Cyclic hydrocarbons (eg. Cyclohexane and turpentine), Esters (eg. ethyl acetate, isopropyl acetate), aromatic hydrocarbons (eg. benzene, tolulene, xylene), alcohols (eg. ethanol, isopropanol), halogenated hydrocarbons (eg. carbon tetrachloride, chloroform), aldehydes (eg. acetylaldehyde, formaldehyde), ethers (eg. diethyl ether, isopropyl ether), and glycols (eg. ethylene glycol, hexylene glycol) (Queensland Health, 1999).
Most solvents aside from chlorinated solvents have the characteristic of a low flash point (<141 degrees Farenheit) giving them the characteristic of flammable. Organic solvents tend to be volatile and evaporate at room temperature and increasingly volatile as the temperature of the solvent solution increases. The lipid solubility of solvents allows the chemical to be absorbed through the skin. The toxicological properties of solvents are dependent upon their chemical grouping, but most have demonstrated adverse effects on the central nervous system, skin system, and the upper and lower respiratory tract. Some organic solvents have been classified as having carcinogenic effects with occupational exposure (Queensland Health, 1999).
SolventsCleaning ProcessesProcessesEquipmentSemiconductor Industry