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Establishing proper safety systems is imperative in sophisticated industries such as the manufacture of semiconductors. Some of the most stringent requirements known in manufacturing are found in the laboratories and cleanroom areas in the field of semiconductors.
To eliminate dust, control vibration, humidity and temperature, the lab environment must be controlled. However, another area is also important. To etch and process the silicon wafers for the production of semiconductors, several highly corrosive and toxic chemicals are required. The use of these chemicals results in toxic gases and vapors and these require a sophisticated gas detector system to ensure laboratory safety. Gas detectors are crucial to safety systems and can also detect Asphyxiants, toxic and flammable gases. Usually, detectors are integrated into a sophisticated control/monitoring system. These can:
- Pinpoint the area of the gas emission
- Interface control systems to automatically shut down a process or area to contain the gas outflow
- Use an alarm to alert personnel to the area of gas concentration
Examples of Gases Used in Semiconductor Production
The cleanroom laboratories contain equipment for etching, photolithography, doping and cleaning. These processes require the use of toxic and corrosive chemicals. For example, the toxic gas hydrogen sulfide is used in gallium arsenide (GaAs) doping, to incorporate sulfur into the gallium arsenide. The toxic liquid carbon tetrachloride is used in plasma etching of silicon as a source of chlorine gas. Other examples of toxic chemicals used for etching and doping include diborane gas, phosphine gas, dichlorosilane and sulfur hexafluoride.
A Gas Detection System for Fab Production
Established in 1917, International Gas Detectors Ltd is a UK-based company. The company provides a broad range of products with detectors suitable for all environments and the widest range of approximately 400 gases. Recently, IGD was asked to provide a comprehensive gas detection system for a new UK-based fab manufacturing plant. The fab company needed a very specific system for gas detection. Specifications included:
- The ability to detect an exotic range of toxic vapors and gases
- All gas detection as a single system for improved safety, end-user training, expansion and service data
- Being able to establish individual areas with cause and effect feedback systems with a 2-Wire safe area addressable gas detection system. This allows a centralized system to provide the necessary local alarm and control.
- The capacity to control third-party equipment and solenoid valves without additional control systems and wiring. Integrated safety systems providing a more secure solution.
- The ability to integrate the system using an HMI controller with data logging, trending and remote GSM alerts.
Using the full range of safe area, ATEX gas zone and sampler units, IGD was able to offer the fab manufacturer fully flexible detection cost-effectively. The specific setup means that the system can control and monitor multiple areas. Although the system was fully implemented by the client, IGD provided full training and design support at every step. For the fab manufacturer, being able to detect a broad range of vapors and gases was very important to the overall success of the detection project implementation.
Advantages of the IGD System
The system was purchased from IGD for several reasons. Firstly, IGD has a long history of technology and systems expertise, with a global reputation. Secondly, the 2-Wire addressable system from IGD provided the fab manufacturer with a cost saving of 70% on installation, compared to less sophisticated analog systems on the market. The system could be purchased from one supplier, with no integration problems. The final reason was the quality of the equipment.
IGD provided long-life (more than five years) ‘Pellistor’ (catalytic) sensors and long-life O2 sensors (more than five years) as well as reliable NO (nitric oxide) and N2O sampler/detectors.
Oxygen sensors from IGD have a unique polymer construction to provide long-life. Pellistor-based detectors are used to detect combustible gases and are an excellent ‘first responder’ for potentially flammable gases.
IGD Pellistor offers a reliable long-life detector solution and has experience in the design of Pellistor-based detectors spanning over 60 years. Generally, the conventional Pellistor and oxygen sensors available from other suppliers only have a lifetime of 18 months to three years. Therefore, the IGD detectors that have a longer life make the system less expensive to install and operate. The same 2-Wire network as was used to install the conventional detectors was used to install the IGD sampler technology into the cleanroom areas.
The samplers offer minimum impact in a cleanroom and only need a small bulkhead sample point, rather than a bulky detector that can trap dirt or bugs. The sample module is then conveniently located for service use outside the cleanroom area. The sampler communicates the data back the same way as any other detector on the network, but it also continuously monitors the sample flow rate.
The Future of the System
The second phase of the system implementation for the fab manufacturer will aim to use the 2-Wire addressable system from IGD in conjunction with a cloud-based data acquisition system. This will mean that the system can be integrated remotely from anywhere straight to the cloud. There is also the requirement to add GSM to the system to allow remote alarm calls and texts and also weekly incident reports. To provide personnel with a comprehensive overview, additional training is planned for the system expansion.
As a technology pioneer, IGD has both the expertise and equipment to provide state-of-the-art fully networked gas detection systems. The addressable gas detection systems use Sentinel+ 2-Wire protocols to provide the best security and operation for integrated gas detection networks. The 2-Wire system requires minimal cabling, which means that it is quick and easy to install, running control devices and detectors off the same network cabling.
Room status monitors provide an indication of the room status from outside, based on the output of up to eight different detectors. These can integrate with room alarms and room entry control. IGD has the ability and knowledge to provide custom system solutions.
This information has been sourced, reviewed and adapted from materials provided by International Gas Detectors Ltd.
For more information on this source, please visit International Gas Detectors Ltd.