Nitrogen Demand Increases for Semiconductor: How Safe Are You?

As users demand ever-smaller smartphones and better televisions, semiconductor manufacturing plants are tasked with developing new products faster and using new materials. Key to the continued success of the semiconductor industry are inert gases, which include nitrogen and argon. When used safely, both nitrogen and argon play a number of important roles within the semiconductor plant. Yet, these gases poses a health hazard for employees if a leak occurs. 

How and Why Nitrogen is used in Semiconductor Manufacturing Plants 

Nitrogen is used throughout the manufacturing process, from purging pumps to abatement. Nitrogen is also used in the process, especially now that fab size is growing. In a modern semiconductor manufacturing plant, as much as 50,000 cubic meters of nitrogen gas are used every hour. 

To meet this demand, semiconductor manufacturing plants are installing nitrogen generators onsite. Generators mean a cheap, efficient, and always-ready supply of nitrogen gas to supply production. 

As long as nitrogen gas is stored safely in the generator and used properly, there is no health risk. Yet if the generator or supply lines develop a leak, nitrogen gas can escape and deplete oxygen in the environment. Since nitrogen gas is both odorless and colorless, there is no way that staff can monitor their risk. 

Along with nitrogen, argon gas is used in semiconductor manufacturing, most notable as a sputtering gas. Like nitrogen, argon gas depletes oxygen from the environment. Like nitrogen, the gas has no color or odor. In a closed area, the gas can deplete oxygen and cause respiratory problems and eventual suffocation. 

How an Oxygen Analyzer Can Protect Staff Working in a Semiconductor Manufacturing Plant 

If either nitrogen or argon were to leak into the plant, these inert gases would begin to deplete the levels of oxygen in the air. OSHA sets the oxygen threshold at 19.5 percent or less oxygen in the air. If oxygen levels fall below this, staff could suffer. 

When oxygen levels fall to OSHA's threshold, staff may show signs of confusion or fatigue. Since there are no warning signs that something is wrong, staff can fall unconscious before they can escape the oxygen deficient environment. Once unconscious, they asphyxiate. 

It is critical for any workplace that uses these inert gases, including semiconductor plants, to monitor levels of oxygen in the air and alert workers if the ambient oxygen levels fall to the OSHA threshold. 

By installing an oxygen monitor and an oxygen analyzer anywhere inert gases are used, manufacturers can protect the safety of their workers through continual oxygen monitoring and fast alert if oxygen levels fall. A wall-mounted oxygen monitor scans the atmosphere and measures the amount of oxygen from 0 to 25 percent, well above the safety threshold. As long as there is enough oxygen in the air -- which there will be as long as there is no inert gas leak -- the oxygen monitor will remain silent. 

When oxygen levels fall to the OSHA threshold, the oxygen monitor will flash lights and sound an alarm, providing instant notification to workers. Staff can take notice and evacuate before negative health outcomes occur. 

An oxygen analyzer measures the level of oxygen present in gas produced via nitrogen generator to ensure the purity of the gas for use in manufacturing. Oxygen analyzers are ideal for low level analysis and can measure from 0 to 1,000 ppm. Workers can check oxygen levels at a glance and ensure the nitrogen generator is working properly. When combined with the oxygen monitor for safety, the oxygen analyzer streamlines and safeguards the semiconductor manufacturing process. 

PureAire offers industry leading oxygen monitors and oxygen analyzers that can last for up to 10 years after installation with no maintenance needed. These products offer worker protection and peace of mind for manufacturers who want to remain cutting edge in their industry. Learn more about PureAire's products at https://www.pureairemonitoring.com.

Oxygen Monitor for Foup's in Semiconductors and Cleanrooms

Over time, the contamination control requirements in the semiconductor industry have become more stringent. Employees now must spend more time adhering to cleaning protocols to preserve the sanitary nature of the environment and comply with regulations. The front-end unified pod (or FOUP) began appearing in semiconductors in the 1990s, serving as a transportation box to safely and securely hold silicon wafers and ensure easier compliance with the industry's  contamination control requirements.

FOUPs allow the wafers to remain in a sterile environment, while also remaining isolated from the cleanroom itself. Not only does this save time, this saves money by lowering the maintenance needs and investments needed to maintain a clean room. Widespread today, FOUPs must be properly cleaned and maintained in order to remain functional. Since a single FOUP can cost $1,000’s so this is not something to be taken lightly by staff. 

Why Cleanliness is Critical to the Semiconductor Industry

Maintaining a cleanroom is so important because air particles can get on equipment or tools and compromise them. During manufacturing processes such as etching, the wafers held inside FOUPs are removed from the isolated environment of the FOUP and then subject to different chemicals. After the etching process ends, trace amounts of these chemicals remain on the wafers. If these were to be returned to the FOUP, they would contaminate the closed atmosphere with chemical residue. This could wreak havoc on the remaining wafers stored in the clean environment of the FOUP. Were this to happen, FOUPs and the wafers inside would need to be cleaned - a very expensive and time consuming process. 

The average FOUP can last for roughly five years before it needs to be replaced. To extend its lifespan and keep all components clean and sanitary, it is necessary to clean FOUPs periodically and to maintain good laboratory habits to minimize mishandling of FOUPs.

Compressed dry air or an inert gas such as nitrogen are common choices for effective cleaning of FOUPs. Studies have shown that passing nitrogen gas over the lower ports and front-end environment of the FOUPs is a reliable way to clean the interior by removing debris and chemical residue stuck inside. While this is useful for reliable FOUP cleaning, introducing nitrogen into the laboratory environment can pose a safety hazard.

Safety Risks of FOUP Cleaning With Nitrogen

Nitrogen gas can displace oxygen if it is released in a closed environment. Were nitrogen to leak from the FOUP and into the clean room, it could reduce levels of oxygen in the air below safe breathing levels. In a worst-case scenario, staff could become sick or die from lack of oxygen. Since both oxygen and nitrogen are colorless and odorless gases, staff cannot tell how much oxygen is in the air, or whether nitrogen used to clean FOUPs has escaped through a leak.
An oxygen monitor can evaluate the levels of oxygen in the air to ensure that nitrogen used to clean FOUPs does not make its way into the clean room, to compromise the air quality and safety there. A wall-mounted O2 monitor takes periodic readings of the level of oxygen in the room. As long as oxygen levels remain in an acceptable range, the sensor will continue to operate as usual. 

If oxygen levels were to drop such that employee health and safety might be compromised, the oxygen deficiency monitor would set off an alarm that would tell staff to evacuate. Staff then have enough time to exit the clean room and avoid health problems associated with oxygen deficient environments. 

When looking for an oxygen monitor for FOUPs, it is vital that the O2 monitor be as hardy and long-lasting as the FOUPs themselves. At PureAire, we make oxygen sensors guaranteed to last for 10 years. Our O2 monitors do not need calibration or maintenance to perform, unlike other brands of oxygen monitors. To ensure a clean, safe environment, while protecting your investment, choose the best in oxygen deficiency monitoring. Learn more about our products at our website, www.pureairemonitoring.com.

Source

http://www.sdram-technology.info/FOUP.html
http://www.entegris.com/Resources/assets/1013-0667.pdf

http://micromagazine.fabtech.org/archive/04/08/keyhani.html