'The Only One in the World' The Future of Semiconductors Depends on Sand Collected from a Remote Village [Tech Talk]

Ultra-High Purity Silica Sand for Semiconductor Materials
Only Found in One Place Worldwide
The Rural American Town Where the Semiconductor Industry Began

It is already widely known that silicon, the raw material for modern semiconductor substrates (wafers), is made from sand. However, not all sand can be processed into wafers. Only a type of sand called 'silica sand' can be used to make semiconductors. This sand can only be found in a small town in North Carolina, USA.

A Rural American Town with a Population of 2,000 Becomes the Starting Point of the Semiconductor Industry

Spruce Pine Silica Sand Mine [Image Source=Sibelco]

In Mitchell County, North Carolina, there is a small town called Spruce Pine. According to Wikipedia, as of the 2020 census, it has a population of only 2,000 residents, making it a rural town. It is so small that not many people in the United States know about it.

However, this town produces sand with a silicon purity that can be used as a semiconductor raw material, unique in the world at present. The sand is characterized by its white and fine particles, reminiscent of a sandy beach or the sand on a golf course. This sand is the raw material for semiconductor wafers.

The sand business in Spruce Pine began as early as the early 1900s. At that time, Americans built railroads and residences in Spruce Pine and mined various minerals, including sand. Even then, the white sand of Spruce Pine attracted much attention, but at that time, the sand was only used for glass production.

The true value of Spruce Pine sand became known from the mid-1950s. It was the dawn of the early semiconductor industry in the United States. At that time, American semiconductor engineers were searching for high-purity sand that could be used as a raw material for substrates to make silicon-based semiconductors.

The only factory in the world that refines and supplies semiconductor substrate raw materials, Sibelco US Spruce Pine Plant [Image source=Sibelco]

However, semiconductors could not be made from ordinary sand. Even 'silica sands' rich in silicon particles were difficult to use as semiconductor materials. Most sands contain various impurities besides silicon, the elemental component of silicon. Silicon wafers can only be made from sand with a purity of 99.99999999999%. After testing thousands of sand samples, scientists discovered the ultra-high purity silica sand from Spruce Pine, and thus the 'computer chips' we use daily today were made.

If the Processing Facility Stops Even Once, the Global Semiconductor Industry Comes to a Halt

So, who mines this precious silica sand and turns it into silicon? A single company called 'Unimin' almost exclusively mines the sand in Spruce Pine. This company is currently part of 'Sibelco,' a Belgium-based multinational mineral company.

Having silica sand does not immediately produce wafers. The silica sand must be refined again to extract purer silicon. Sibelco extracts pure silicon from the sand through the 'Czochralski process,' which is kept strictly confidential in the industry, and then forms it into crucibles. These crucibles become ingots shaped like pillars, which are then sliced thinly and polished to create smooth surfaces, finally producing wafers?the starting point of all semiconductors.

Refined silica sand is made into silicon ingots, which are then thinly sliced to become semiconductor substrates. In other words, without silica sand, the entire semiconductor production process comes to a halt.
[Image source=Fujitsu, a Japanese semiconductor company website]

The ultra-high purity silica sand capable of making semiconductor wafers is called the 'IOTA' standard. So far, IOTA-standard silica sand has only been found in Spruce Pine. In other words, this small town with a population of about 2,000 is the starting point of the entire semiconductor industry.

What would happen to the global semiconductor supply chain if something were to happen at the Spruce Pine mining site? In fact, in 2008, a fire broke out at one of the ingot production facilities in Spruce Pine. This temporarily halted the supply of IOTA-standard sand, nearly paralyzing the global semiconductor industry.

Scholars are also actively searching for alternative silica sand candidates to replace Spruce Pine, but so far, there has been no significant success. Spruce Pine remains the only place on Earth where silica sand with 99.99999999999% purity is found.

The semiconductor industry is characterized by global-scale division of labor and supply chains extremely concentrated in a few companies. Taiwan's TSMC, the world's leading contract manufacturer, and the Netherlands' ASML, which virtually monopolizes advanced EUV lithography machines, are representative examples. Spruce Pine is another example that shows how fragile the production process of computer chips, which are most important to sustaining human civilization, actually is.