scope:

This guideline aims to compile the existing expertise regarding the planning, construction, operation and monitoring of water-processing installations for the production of ultrapure water.

It applies to the quality requirements, the production and the supply of ultrapure water for processes with high cleanliness requirements such as those common in cleanroom technology. Similar processes and systems are used in conventional and nuclear power plants; these, however, are not within the scope of this guideline, being described elsewhere.

The ultrapure water is used in various applications:

• on the one hand, for cleaning processes, and
• on the other hand for diluting highly concentrated ultrapure chemicals to working concentrations, or
• as part of a product to be produced.

Contaminated surfaces, for instance, are cleaned using ultrapure water before sensitive processes are carried out.

Ultrapure water shall meet high requirements in terms of particulate, chemical and biological cleanliness when applied.

In the field of microelectronics/semiconductor technology, marked by the downsizing of the structures, the emphasis lies on the removal of all particulate, chemical and biological contaminants to the extent feasible.

The structure of the ultrapure-water systems used consists of:

• treatment including pretreatment
• storage and distribution
• use including quality monitoring

The process steps required in ultrapure-water treatment, and thus the system structure, depend on the raw-water analysis, affected by the prevailing local conditions, and on the ultrapure-water target analysis specified for the application in question. Basic environmental conditions such as the requirement of reduced use of chemicals and the site-specific cost of water and other operating costs also have an impact on the selection of the individual process steps.

Storage and distribution are determined by the local installation conditions and the consumer units to be connected.

Generally speaking, it is essential that an economic solution be developed from the multitude of possible approaches.