Consider a modern computer central processing unit or CPU. Many dozens, up to 60, highly purified chemical elements can come together to produce a CPU. The production of highly purified raw materials like chemical vapor deposition chemicals used in chip manufacture requires a stack of apex technologies to produce the purity and economics needed. The American Chemistry Council has an informative website articulating the role of chemistry in chip manufacture. To sustain the computer industry, mining companies need access to economical ore bodies for mineral extraction.
A few elements are particularly scarce. One such element is indium. Indium is 90 % available as a side stream of zinc refining. There is no US production. The main use is for the production of Indium-Tin-Oxide, ITO, as a transparent conductor for telephone touch screens. Indium market scarcity is based on the production rate of zinc, not the crustal abundance of indium. For this reason indium suffers from price inelasticity.
Why do I say a stack of apex technologies? The application of any given device or material depends the quality or purity as a specified input of each successive raw material. This goes all the way back to the mine. Purified intermediates from selective isolation of indium from the zinc process, selective isolation of indium oxide from an oxidation process, precise blending with tin oxide and coating on specialty glass. Oh yes, every manufacturer in the series must make a minimum profit too.
Every chemical manufacturing step requires careful processing to spec, satisfactory economics and the obligation to avoid patent infringement. Getting around a patent may carry economic penalties. A stable process means that process development is complete, yields maximized, purity optimized and attention to process drift is in place 24/7.
Below is a list of Indium, ITO or touch glass suppliers in the ITO market-
- American Elements, Indium Tin Oxide is a solid solution of indium(III) oxide (In2O3) and tin(IV) oxide (SnO2) with unique properties as a transparent semiconductor material.
- Umicore, Metals range from precious metals (Ag, Au, Pt, Pd, Rh, Ir, Ru) to base metals (Pb, Cu), minor metals (In, Te, Se, Sb, Sn, Bi)
- Indium Corporation, variety of products that include solders and fluxes; brazes; thermal interface materials; sputtering targets; indium, gallium, germanium, and tin metals and inorganic compounds; and NanoFoil.
- Keeling & Walker, Ltd. Keeling & Walker provides high purity tin oxides with a minimum purity of 99.99%. They also provide tin oxide with specific limits for individual trace elements. They offer high purity materials based on thermal oxidation, as well as from wet chemical processes.
- Mitsui Mining & Smelting Co., Ltd., Primary in Zinc production and indium byproduct.
- Samsung Corning Precision Material, The company includes products such as glass substrates for LCD
- Touch International, From heavy duty outdoor terminals to delicate handheld medical devices, unique applications have unique touch, display, and cover lens requirements.
The supply lines for each chemical input to semiconductor manufacture are built to yield highly purified intermediates and products. To do this, a manufacturer must utilize their best efforts consistently. Having to rework a chemical product will result in 5-50% losses and extra plant time and material costs. Rework is never a good thing.
Quality control at the ppm to ppb level or below is never trivial. Use of the customer’s analytical methods verbatim is highly preferable or even mandatory. A very clean lab with ultra purified air and packed with highly sensitive instruments (ICP) and spec or analytical grade chemicals mas well as a well educated and trained staff to do the work is essential. Pulling samples cleanly from the process is an art unto its own and you best be ready. There are many learning curves to climb here.
The suppliers who ship directly to a semiconductor plant, i.e., a FAB, face purity specifications up to nine nines purity based on each of multiple contaminants. There are likely no lot tests signaling approval for received lots. A lot approval would require the FAB to do full test run in the plant at a frightful cost so they will not do it. This is a very scary place to be for a supplier. Shutting a plant down for weeks could happen as they investigate the cause of a disqualifying event. Somebody will have to pay.









