Nanoelectronics industry is the new name for what recently was called Microelectronics industry. It is a similar concept as Semiconductor industry but is a bit wider.
Ultrapure Water (UPW)
UPW is highly purified water, presently in three grades. The highest grade is for the semiconductor industry (Type 1), the second grade is for the pharmaceutical industry (Type 2) and the third grade is for the power industry, as boiler feed water (Type 3). Also other uses exist, i.e. lab water.
A nanoelectronics manufacturer may use several millions of liter per day as rinse water to clean the components after each stage in manufacture.
The semiconductors consist of transistors (switches) that are built into integrated circuits. A large number of distinct integrated circuits are manufactured on the basis of a wafer (generally a thin dish of silicon) where each distinct unit is called a die. After it has been cut out from the wafer it is often called a chip or microchip. The chips are provided with connections (interconnect) and packaged into functional devices such as processors, memories, application specific integrated circuits (ASICs), photovoltaic cells among many other.
With line width we mean the distance over the switches in an integrated circuit. The shorter the distance, the quicker and more compact will be the device. Although not entirely interchangeable, line width may also be called gate length or node. Present best commercial line widths are above 20 nm. Advanced production has started at 14 nm line widths and research is done on linewidths down to 5 nm.
Nanometer – nm One nanometer is one billionth of a meter which is also one millionth of a millimeter.
Yield rate is the percentage of approved products in the final testing. At first runs of a new semiconductor plant, the yield rate can be as low as 3-4%. After a while it can be 30 – 70 % and then go up in the 90ies when the process has been adjusted properly.
Defects are due to three major causes: a few percent from defects in materials, some 10 % from remaining processing errors, including photolithography and mask defects. The rest is from contamination by unwanted particles.
Particles that are large enough to cause short circuit at a certain line width. So, in general terms, a particle larger than 14 nm may cause short circuit at 14 nm line width. However, several smaller particles may also combine into causing a short circuit. A short circuit anywhere in the microchip will mean that the finished microchip will be discarded in the final test of the product. High failure rate causes a low yield rate which may influence the economy of the production considerably. To increase yield rates is always a target for nanoelectronics manufacturers.
Reuse of water
Recycle means to treat the waste water from a process in such a way that it can be reused in the same process (in a closed loop). Recover would then mean to treat the effluent in such a way that it can be used in other – less exacting – processes in the same plant. Reclaim would mean to clean the effluent in such a way that it can be beneficially used for other purposes outside of the plant. Without removal of nanoparticles, the semiconductor industry cannot recycle its water.
Recovery of materials
In the manufacture of semiconductors and other nano devices many expensive materials are used such as gold and silver and especially rare earth metals which are only found in specific locations and in limited quantities. To be able to recover these in a simple way will be extremely profitable.
Some other materials, such as arsenic and cadmium, must be recovered to avoid danger to the environment. This may not be profitable to the individual industry but nonetheless very desirable.
Xzero’s polygeneration system reuses local waste energy and tops up with renewable energy resources to supply all types of local energy demands, such as electricity, space heating and cooling, hot water, process cooling, and also recycling of process water and recovery of materials.
Zero liquid discharge
Zero Liquid Discharge (ZLD) means that no waste stream leaves the factory. All waste streams are processed into reusable water and solids. The solid residue can be recovered. In any water purification process, clean water is separated from contaminants. In ZLD the contaminants are concentrated until they become a sludge and then further into solids. In Xzero systems all the water extracted in the concentration process can not only be reused, but also recycled as UPW.