Background

NXP Semiconductor is a major manufacturer of MEMS, microcontrollers, radio frequency transceivers and amplifiers. At their Austin, Texas, facility, the fab has a cooling tower in a central utility system, supporting the chillers that supply process cooling water to the fab. Like most semiconductor manufacturers, NXP has strong environmental and local community commitments.

The fab’s biggest challenge was finding a way to reduce water use and discharge without jeopardizing utility support functions.

One obvious option is to reclaim water from the fab’s processes for use in the utility centre’s cooling towers. However, this could only work with protections against contaminants in the fab’s reclaimed process water. Such contaminants include phosphates, fluorides, sulfates, chlorides, ammonia and silica, as well as naturally occurring hardness (calcium and magnesium), which can increase the risk of corrosion, microbio and scale in the cooling water system. An adaptable water treatment programme is key to managing these risks as well as optimizing the related mechanical, chemical and operational conditions.

Solution

Through in-depth discussion with NXP personnel, the Nalco Water team gained a solid understanding of the reclaimed water streams. In response, Nalco Water proposed a 3D TRASAR Technology for Cooling Water programme, which uses three major innovations to provide flexible control for microelectronics fabs:

• Real-time corrosion monitoring and control
• Chemistry that outperforms traditional polyphosphate scale and corrosion inhibitors
• Tagged and inert fluorescent polymers that enable the chemical programme to adapt in real time to changes in stress

In addition to the 3D TRASAR programme, NXP and Nalco Water implemented a process that included complete overhaul of automation systems.

Chemical delivery and storage systems

The Nalco Water PORTA-FEED™ system drastically reduced the number of chemical drums on site, thereby reducing drum handling for NXP staff.

New chemical treatment programme automation

The equipment associated with the 3D TRASAR Technology for Cooling Water programme occupied a much smaller physical footprint than NXP’s previous chemical control automation and feeding system. This space-saving design contributed to a much tidier appearance and less clutter in this area of the fab.

Results

After switching to the 3D TRASAR programme, corrosion rate was reduced by 93% and real-time corrosion data is now provided.

The 3D TRASAR programme includes support from the Ecolab Global Intelligence Centre (EGIC), which monitors performance trends, reviews alarms and troubleshoots systems 24/7. The EGIC can contact local Nalco Water personnel or fab staff to initiate corrective action before a small problem becomes a large incident.

The 3D TRASAR programme’s ability to tolerate variable water quality enabled the fab to increase the cycles of concentration in the cooling tower from 7 to 15. The programme also enabled NXP to use more reclaimed water.

Municipal water consumption was reduced by 7.2 million gallons (27,250 m3) annually, resulting in cost savings of $23,680.

Discharge flows were reduced by 8.5 million gallons (32,180 m3) annually, resulting in $47,185 of additional cost savings.

Labour to operate the programme was also optimised, saving $30,000 and allowing operations staff to focus on higher value tasks. Overall programme costs were reduced by $14,000 as well. Lastly, the project came in under budget, ahead of schedule and exceeded savings targets.

Taken together, the significant benefits of the 3D TRASAR Cooling Water programme are valued at $114,865 per year.