Indium Phosphide Under RoHS
The MMTA recently coordinated industry input to the EU’s RoHS Consultation on indium phosphide (InP), which was included in the list of seven shortlisted substances. The full list of substances is:
- Diantimony trioxide (flame retardant)
- Tetrabromobisphenol A (TBBP-A, flame retardant)
- Indium phosphide (InP)
- Medium chain chlorinated paraffins (MCCPs) – Alkanes, 14-17, chloro
- Beryllium and its compounds
- Nickel sulphate and nickel sulfamate
- Cobalt dichloride and cobalt sulphate
The MMTA worked closely with industry associations representing the other affected substances. The information provided is based on input from a cross-section of InP industry experts, drawn together by the MMTA, acting in support of one of its constituent industry sectors.
The key points the industry wished to stress in this submission are that volumes are several decades lower than stated by the EU consultants, that the use of indium phosphide is critical and irreplaceable in its key applications, and that any inherent risks are well managed.
Applications in which indium phosphide is used
Compound semiconductors provide the core photonics technology behind the Internet of Everything and all Big Data systems. InP technology is key to the entire internet infrastructure.
Fiber optic communications are by far the most important and critical current use of InP. Indium phosphide is a III-V semiconductor with much higher electron mobility than silicon. InP is mainly used in high power and high frequency optoelectronic devices including laser diodes, LED, photo detectors, optical transceivers, which are operating in optical fiber communication systems. These devices, along with InP based transistors, are fabricated by the epitaxial growth of III -V ternary and quaternary compound semiconductors on InP substrates.
It should also be noted that InP-based tele- and data-communication systems offer unprecedented and several orders of magnitude higher energy efficiencies, and lower environmental impact, compared with legacy/incumbent systems e.g. copper. The ability to support the continued explosion of growth of data transmission and storage requirements over the coming years is becoming paramount.
Examples of other applications of InP include:
- Data centre communication systems RF/satellite communications
- Night vision/military applications wireless devices
- Power control systems
- Gas detection
- A wide range of sensors
- LIDAR (Light detection and ranging) for autonomous and assisted vehicles is a fast- growing market
Indium phosphide is critical to enabling high value supply chains in a range of sectors including:
- Energy Efficiency
- Internet of Things
It should also be noted that the application of InP in professional test and measurement equipment is critical for the continued development, qualification and manufacture of both current and next generation communications optical/photonic fibre network applications. Any potential restriction in the use of InP applicable to professional test and measurement equipment will therefore impact innovation of the next generation of such devices and limit any investigation into substitution possibilities across all EEE sectors.
Indium phosphide manufacture is a tightly controlled process and the materials used are valuable. Great care is taken to collect and recycle materials arising from the production process. The process materials which cannot be used are shipped under controlled regulations to a licensed recycling facility which recovers the metal and returns value to the indium phosphide wafer manufacturer.
Records are kept of each shipment, so full traceability is ensured. The recovered metal is then refined for use in this or other applications.
Quantities and ranges in which indium phosphide is in use
Usage estimates are far from accurate, including those conflating indium metal, ITO and InP. For the purpose of this submission, the focus was on the following applications and quantities placed on the EEA market annually:
- Fiber-optic networks, wireless base stations and satellite communications – annual EU/EEA consumption 9-10KG
- Other laser and sensor applications, LIDAR autonomous driving, vehicle emissions testing, spectroscopy analysis for food, chemical analysis – annual EU/EEA consumption 6KG
Electronic semiconductor applications:
- High speed (Terahertz) Hetero-junction Bipolar Transistors in measurement analysers and non-military radio frequency communications – annual EU/EEA consumption 8Kg
This gives a total annual EU/EEA consumption of approximately 24KG of InP contained. Working on the estimate that EU/EEA represents between 20-25% of the global market, this would mean a global total of between 96 and 120KG per year.
Military uses of InP in laser guidance systems including guided weapons and THz HBT transistor semiconductors in communications and decision-making applications are almost certainly far greater than uses in EEE products within the scope of RoHS.
The amount of InP used in an individual optoelectronic component is also very small, averaging between 0.23 and 1 mg.
During the manufacturing process a proportion of the InP wafer is ground away and the backgrind slurry is safely disposed of as hazardous chemical waste using a specialist chemical disposal company. Any whole, unused wafers are sent to a specialist company for re -use. Neither of these raw material process waste streams are within the scope of RoHS.
As amounts of indium phosphide in finished products are very small, compared to the amount purchased, it is considered to present a low risk to recycling workers handling the end of life electronic products.
Indium phosphide has unique properties and no viable substitutes are on the horizon. The Oeko Institut background documentation suggests several substances for which InP might itself be a substitute; it is, however, incorrect to state that gallium arsenide (GaAs) is a viable substitute for InP, except potentially in some minor applications. In fact, InP was introduced as a substitute for GaAs in the past, as it was found to have better performance. It should also be noted that GaAs has a comparable risk profile to InP.
Currently, InP is the only substance viable for its existing uses in semiconductors. InP is the unique material for substrates of III-V ternary and quaternary compound semiconductors which have a direct energy bandgap of 1.344 eV and can cover the wavelength range from 0.9 µm to 2 µm. There is no alternative available, as InP is the only material to make the laser at the required wavelengths.
In the photonics/optical communications field, silicon can perform some of the functions of InP, but as silicon does not emit light, InP is still needed, so this is not a solution. Indeed, the silicon and semiconductor industries work together and complement each other, providing increasing integration.
In the data centre applications, it should be noted that silicon germanium technology has some limited functions, however, it is unsuccessful where there are greater distances between individual data centres.
There is no substitute to InP with equivalent performance and, given its economic importance, indium has been classified a Critical Raw Material (CRM) to the EU.
Socio economic impact of a possible restriction
Industry representatives are confident that quite simply put, telecommunications networks delivering the global internet, would not survive without the use of InP, and that it is essential for the current and future digital landscape.
Global communications networks operate through the use of InP lasers that connect switches and routers within and between data centres and throughout the global Internet. European companies help support a global EUR 25 billion industry in optical networking equipment and components, which supports a nearly EUR 3 trillion global industry in telecommunications services. This does not include European jobs and revenues associated with e -commerce, social media, streaming entertainment, and other online businesses. It is even realistic to say that nearly the entire European economy of EUR 15 billion, and the entire EUR 67 trillion global economy, depends in some way on InP-based optical communications, because nearly every business today is somehow connected to cloud-based and other networking services.
Any socio-economic assessment would need to consider the viability, availability and reliability of parts and/or products employing substituted materials.
In summary, telecommunications, including the global internet data centres, the cloud, all data transfers, mobile 4G and 5G, all require fiber optic infrastructure, and there are no alternatives to indium phosphide. Without InP, the technological clock would need to be turned back 40 years. The global economy is completely reliant on digital communications, and its disappearance is impossible to imagine.
Indium phosphide presents an enormous economic benefit, and with such low volumes consumed globally, any risks from its use are minimal, not forgetting the risk factors of potential alternatives, however inadequate.
Maria Cox, MMTA
Image: Optical Fibre Network for the Internet Source: IMAT
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