Manufacturing cleaning process

CFCs have been widely used as cleaning solvents, as they are nonflammable and their toxicity is low. Now, flammable solvents are coming back into favor. A news item from a manufacturer described "a new ozone-friendly cleaning process for the electronics industry, which "uses a unique hydrocarbon-alcohol formulation. It did not remind readers that the mixture is flammable and that they should check that their equipment and procedures are suitable. 

All standard cleaning processes for silicon wafers are performed in water-based solutions, with the exception of acetone or (isopropyl alcohol, IPA) treatments, which are mainly used to remove resist or other organic contaminants. The most common cleaning procedure for silicon wafers in electronic device manufacturing is the deionized (DI) water rinse. This and other common cleaning solutions for silicon, such as the SCI, the SC2 [Kel], the SPM [Ko7] and the HF dip do remove silicon from the wafer surface, but at very low rates. The etch rate of a cleaning solution is usually well below 1 nm min-1. 

CIP systems are commonly used to eliminate environmental and personnel exposure to the contaminant. They are effective when the shutdown and disassembly of equipment in production would impact manufacturing efficiency. They are also used to improve the consistency and reproducibility of the cleaning process. 

Vahdation procedures must be applicable to computer systems cleaning processes manufacturing processes heating, ventilation, and air-conditioning systems water systems and analytical methods and equipment. 

New products, particularly potent drug products, can present cleaning problems in existing equipment. Manufacturers must validate their cleaning processes for the new drug/dosage form. 

Eventually the point will be reached at which the development of a product is complete the formulation is finalized, the equipment has been selected, the analytical methods are validated, the development transfer report has been issued, and the Preapproval Inspection (PAI) is anticipated. Now is the time to consider validation of both the manufacturing and cleaning processes. Although some process validation may have also been completed or a process validation protocol may have been prepared and approved, it is likely that very little has been finished that would enable us to state that the cleaning process is fully validated. 

As one of its Guides to Inspections, the FDA introduced Guide to Inspections. Validation of Cleaning Processes in 1993 [9], This broadened the area of validation considerably by focusing on fields other than the manufacturing process itself. As time showed, further additions, such as Test Method Validation and Computerized Systems Validation, developed as validation topics on their own. The regulations and literature for these specialized fields will not be discussed here. The reader is invited to consult the relevant chapters of this book where the information is available. 

U.S. Food and Drug Administration. Guide to Inspections Validation of Cleaning Processes. Rockville, MD Division of Manufacturing and Product Quality, Office of Compliance (1993). 

The FDA does not intend to set acceptance specifications or methods for determining whether a cleaning process is validated. The user s rationale for the residue limits established should be logical, based on the manufacturer s knowledge of the materials and the practical, achievable and verifiable data. The objective of the inspection is to ensure that the basis for any limits is scientifically justifiable. However, unlike product residues, it is expected that no (or for ultra-sensitive analytical test methods, very low) detergent levels remain after cleaning ... 

Once the stage has been reached at which the product has been developed and the formulation and batch size determined, it is time for validation of the manufacturing process and the cleaning process. By that... 

Cleaning processes are considered as critical manufacturing steps, and as such, must be validated. 

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