Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
2000-07-10
2003-11-11
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S109000, C510S110000, C510S363000, C510S439000, C510S477000, C510S488000, C428S320200, C210S501000, C210S924000, C210S925000, C134S042000, C134S006000
Reexamination Certificate
active
06645930
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to clean room wipes, and to methods for preparing and using such wipes, so as to reduce or eliminate the possible spontaneous combustion of wipes after contacting chemicals often found in clean rooms. Specifically, our invention relates to wipes used in a “clean room”, semiconductor fabrication plants, metal-plating plants and in other applications and environments to clean up alkaline (caustic) spills and contaminants.
BACKGROUND OF THE INVENTION
Clean rooms are being used in a growing variety of industrial processes, especially processes such as semiconductor fabrication processes, where there are very stringent requirements for maintaining cleanliness.
Contamination, even by bits of lint or dust, can bridge these circuits and cause such devices to be defective and is a major source of rejection. Particles and contaminants, even the smallest particles and contaminants, are frequently many times larger than feature sizes in the individual transistors and diodes in microelectronic devices. Any such particles and other contaminants present during the semiconductor fabrication can cause serious functionality and reliability problems in the final manufactured devices.
Therefore, there is a need to maintain all surfaces as free from such contamination as possible. This is usually accomplished in part by wiping these surfaces, and a number of specialized wipers have been developed for this purpose. However, the wiper itself, in addition to being able to wipe cleanly, should not contribute to the problem of dust.
Clean room products, for example wipes, gloves, gowns, tools, electronic components, filters, and reactants, must be designed and manufactured to avoid contamination. Clean room wipes used in sensitive areas, such as semiconductor fabrication clean rooms and pharmaceutical manufacturing facilities, must be carefully selected for characteristics such as particle emission levels, levels of ionic contaminants, adsorptiveness, resistance to attack or degradation by wear or exposure to cleaning materials, and lack of attack by or degradation by biocides, among other factors.
Stringent clean room requirements have been met by the provision of specially fabricated products. These products include “applicators” and “wipes”. These products are designed to emit very few loose particles or ions, while maintaining structural integrity when used. One example is a wipe described in EP0336 661 A2 to Paley et al. Other examples of such applicators or wipes and their method of manufacturing are described in U.S. Pat. No. 5,271,995 to Paley et al. and U.S. Pat. No. 5,227,844 to Bhattacharjee et al., the disclosures of which are incorporated herein by reference.
The contamination which is to be controlled is often called “microcontamination” because it consists of small physical contaminants, such as particulate matter of a size between that of bacteria and viruses, and chemical contaminants in very low quantities, typically expressed in parts per million or parts per billion. Clean room levels define acceptable levels of contaminants by size. Clean room levels are indicated in Table 1.
TABLE 1
Maximum Number of Particles per cubic foot of air greater than
or equal to various sizes in selected classes of clean rooms
0.1 micron
0.2 micron
0.3 micron
0.5 micron
5.0 micron
Class 1
35
7.5
3
1
NA
Class 10
350
75
30
10
NA
Class 100
NA
750
300
100
NA
Class 1000
NA
NA
NA
1000
7
During normal manufacturing and maintenance operations within the clean rooms used for integrated circuit manufacturing, pharmaceutical manufacturing, and metal plating operations, there are many situations when structural surfaces must be wiped clean with either dry or saturated wipes to remove particles, ions, or chemical contamination.
Like particulates, chemical spills within clean rooms and metal plating plants are also a major concern. These chemicals will release chemical vapors, droplets (particles), and can cause corrosive damage to equipment, personnel and integrated circuit products.
During the fabrication of semiconductor devices numerous corrosive and/or reactive chemicals must be used. Very often there are chemical spills during chemical transfers to the baths or automated equipment. Such spills can also take place during the transfer of wafer boats between different tanks. Many times there are also chemical spills down the side of the containers that must be removed. These chemicals can be very hazardous to personnel, equipment and the semiconductor devices if not properly controlled.
During the metal plating operations there can be spills of corrosive and strong oxidizing solutions. These solutions are hazardous to the personnel and can also be a significant fire hazard.
Normally these chemical spills are composed of mineral acids, aromatic solvents, ketones, alcohols, amines (NMP) and alkanolamines (monoethanol amine, diglycol amine, etc.). Metal plating operations may have caustic or organic solvent based chemistries with various metal ions in different oxidized states. Wipes that are dry or saturated with water or isopropyl alcohol have heretofore been used to clean up these chemical spills.
Recently a new class of chemicals has become very important in the manufacturing of the IC devices. This class of chemicals contains hydroxylamine and hydroxylamine compounds mixed in a variety of amine and alkanolamines. The pHs of these solutions are usually between 9 to 11.5. These chemistries have proved to be very effective because of the unique reductive power of the hydroxylamine compounds. Examples of such chemistries are in such patents as U.S. Pat. Nos. 5,279,771, 5,381,807, and 5,482,566.
Prudent practices when wiping up hydroxylamine should include quenching the wipe in water before disposal. However, clean room personnel can not always be relied upon to quench these wipes. One potential problem is that when these chemistries are spilled and need to be wiped up the hydroxylamine will react with various ions and oxygen and will undergo autocatalytic oxidation. There is also the potential for an exothermic reaction between the wipe materials and the contaminant, and resulting spontaneous combustion, especially from alkaline chemistries such as hydroxylamine-based formulas. These reactions can generate thermal energy and under certain conditions can generate enough heat to allow the wipes to smolder and generate smoke and steam.
Many times clean room personnel have not adequately quenched the wipes and the spontaneous combustion has taken place.
Metal plating solutions will also have chemicals in different oxidation states that need to be neutralized to reduce the possible spontaneous combustion problems.
It is an object of the present invention to solve or alleviate the foregoing problems. Accordingly, it is an object of the invention to produce clean room products, particularly clean room wipes that can neutralize chemical spills, particularly those spills containing hydroxylamine compounds. In particular, it is an object of the invention to provide clean room wipes which can also neutralize amines, hydroxylamine, and alkanolamine, without degradation of the clean room quality of the products. It is a further object of the present invention to provide such clean room products saturated with acids that can neutralize these amines, alkanolamines and hydroxylamine and which are relatively simple to use. This invention is not intended to neutralize caustic based cyanide plating solutions, since there may be a release of the deadly hydrogen cyanide gas if the wipes of this invention were to be used for that purpose. The foregoing and other objects and advantages of the invention will be set forth in or apparent from the following description.
SUMMARY OF THE INVENTION
The wipes of our invention have an absorbent substrate containing at least one organic acid. The acid is capable of reacting with and neutralizing caustic in spilled chemicals. The absorbent substrate can be of any type known in the art to be useful for clean rooms, that is, a s
Small Robert J.
Wallis Danny L.
Douyon Lorna M.
EKC Technology, Inc.
Pennie & Edmonds LLP
LandOfFree
Clean room wipes for neutralizing caustic chemicals does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Clean room wipes for neutralizing caustic chemicals, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Clean room wipes for neutralizing caustic chemicals will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3138666