Technology & Semiconductor

Semiconductor fabrication uses some of the most toxic gases in industry, at exposure limits far lower than anything a conventional four gas instrument is built to measure. It also protects equipment where a false suppression discharge can cost more than the fire would have.

Most of what follows comes from work our Technical Consultants have done on Australian facilities.

The Gases That Make Chips

Methane, carbon monoxide and phosphine are key ingredients in semiconductor fabrication rather than by-products of it. They appear throughout a facility, in gas cabinets, wafer dryers and wafer reactors.

The processes that use them are deposition, photolithography, doping and etching, where the gases act as catalysts driving reactions at the molecular level to produce diodes, transistors and the devices built from them. Acids including hydrogen chloride are used for similar purposes, and the fumes cause irritation and affect respiration.

What makes this different from other industries is not the number of gases, it is how little of them matters. The hydride gases used in doping, including phosphine, arsine and diborane, carry exposure limits among the lowest of any industrial gases, at fractions of a part per million. An instrument that resolves carbon monoxide adequately at 1 ppm is nowhere near sensitive enough for these.

That drives the detection design. Fixed detection in flameproof form covers gas cabinets, tool exhausts and storage, reporting to a controller with audible and visual alarms, since a facility this size cannot rely on somebody noticing a panel. Portable multi-gas and single gas instruments cover maintenance and cylinder handling.

The S-Guard electrochemical variant covers more than 50 target gases, including the specialty set: arsine, diborane, disilane, germane, boron trifluoride, boron trichloride, chlorine trifluoride and fluorine, alongside the common toxics. That range is unusual, and it’s the reason the S-Guard appears on this page rather than a general purpose transmitter.

AS/NZS 60079.29.1 governs the performance of flammable gas detectors used in these installations.

Flame Detection Goes Inside The Tool

This is where semiconductor departs from other industries entirely.

Elsewhere, flame detection watches a room, a bund or a process area. In a semiconductor facility the detector sits inside the process tool itself, as a critical component of that tool’s own fire suppression system. Detection distance is short, often only a couple of metres, and the placement question is where inside the tool rather than where in the building.

Which makes detector selection specific rather than general. Different fuels produce different flame signatures, so the detector has to be able to see the signature produced by the chemistry running in that particular tool. A detector correct for one process tool may be blind to a fire in the next one along.

The high risk positions are the wet bench, the solvent wet bench and the process tank, where flammable and combustible liquids are handled in quantity.

Response time matters more here than detection range. A 40 millisecond response reduces the risk of a volatile fluid explosion developing, which is the failure mode these systems exist to prevent.

The industry carries a set of fire hazards that do not appear together anywhere else: high contamination potential across both products and production tools, flammable and combustible liquids, clean rooms, exhaust systems, oxide layer faults from electrostatic discharge and high voltage transients, and corrosive materials.

That first one is the reason false alarm immunity is worth paying for. In a clean room, a suppression discharge contaminates product, tooling and the room itself. The cost of a false activation is measured in scrapped wafers and days of decontamination rather than in the price of the agent. The F-Guard UV/IR responds to a fireball in 5 milliseconds and requires both sensors to agree before alarming, which is the combination this application needs.

Certification for tool mounted detection typically covers Class I Division 2 Groups B, C and D, equivalent to Zone 2, along with Class II and III Division 2 Groups E, F and G, and SIL 2 to IEC 61508 where the detector forms part of a rated safety function.

Data Centres And Battery Rooms

For most Australian technology facilities this is the more likely application, and it is growing quickly.

Uninterruptible power supply rooms and battery installations bring their own detection requirement. Lead acid batteries generate hydrogen during charging through electrolysis, which is an accumulation problem solved with fixed detection tied to room ventilation. Lithium-ion batteries release electrolyte off-gas well before thermal runaway, which is a different problem with a different answer.

The Li-ion Tamer detects that off-gas, and the detail worth knowing is that ethylene released from the anode during cycling appears before venting, before smoke and well before runaway. Sensor placement matters as much as sensor choice, and detectors positioned in the path of a supply fan are being fed clean air regardless of what the room is doing.

There is also a certification trap on these projects. Where the client is an international operator, the engineering standard applied is often the parent company’s rather than the Australian one, and FM approval and IECEx are not interchangeable. Establishing which is required before equipment is ordered avoids discovering it at commissioning. This is covered further on our power generation and BESS page.

Who Regulates It

Semiconductor and technology facilities fall under general work health and safety law, so the regulator is WorkSafe WA, SafeWork NSW or Workplace Health and Safety Queensland depending on location. Safe Work Australia publishes the exposure standards these limits derive from, and does not itself regulate or inspect.

Facilities holding more than threshold quantities of scheduled chemicals may also be classified as major hazard facilities, which is regulated separately and in Western Australia sits under the Dangerous Goods Safety Act 2004 rather than the Work Health and Safety Act. Specialty gas storage brings dangerous goods obligations in its own right.

Standards relevant to detection include AS/NZS 60079.29.1 for flammable gas detector performance, AS/NZS 60079.29.2 for their selection, installation, use and maintenance, AS 2865:2009 for confined space entry, and IEC 61508 where a detector forms part of a rated safety function.

What Gastech Supplies

Fixed gas detection covering specialty and hydride gases as well as the common toxics, for gas cabinets, tool exhausts, storage and process areas.

Flame detection for process tools, wet benches and solvent handling, selected against the chemistry present rather than by range alone.

Portable multi-gas and single gas instruments for maintenance, cylinder handling and confined space entry.

Controllers with the relay capacity to drive suppression, isolation and ventilation, and sounders and beacons so an alarm reaches people rather than sitting on a panel.

Behind them sit project engineering, NATA calibration and service, field service, fleet management and hire, from WA, NSW and QLD.

If you are specifying detection for a process tool or a battery room, or need a sensor for a gas most suppliers do not stock, talk to our Technical Consultants.