Raw Materials (Mined)
Semiconductors begin with raw materials extracted from the earth. These inputs—quartzite, rare metals, and byproducts of other mining industries—form the foundation for silicon wafers, compound semiconductors, and specialty devices. Unlike fab consumables, raw materials exist far upstream, and their availability is shaped by geology, mining economics, and geopolitics. Control over these resources has become a national security priority as countries seek to secure semiconductor supply chains.
Key Raw Materials
- Quartzite (SiO2): The primary feedstock for metallurgical-grade silicon, later refined into polysilicon for wafers.
- Gallium (Ga): Extracted as a byproduct of bauxite/aluminum refining, essential for GaAs and GaN compound semiconductors.
- Germanium (Ge): Recovered as a byproduct of zinc ore processing, used in solar cells and infrared optics.
- Indium (In): Byproduct of zinc and tin smelting, critical for InP and optoelectronic devices.
- Tantalum (Ta) & Tungsten (W): Conflict minerals mined in Africa and Asia, used in diffusion barriers and interconnects.
- Rare Earths: Neodymium, cerium, and lanthanum used in polishing powders, lasers, and magnets for semiconductor equipment.
Raw Materials Mapping
| Material | Source | Use in Semiconductors | Strategic Risk |
|---|---|---|---|
| Quartzite (SiO2) | Mined from high-purity silica deposits | Converted to MG-Si, precursor to polysilicon | Energy-intensive refining; concentrated supply |
| Gallium (Ga) | Byproduct of bauxite/aluminum refining | GaN, GaAs semiconductors for RF & power | China dominates global production |
| Germanium (Ge) | Byproduct of zinc ore processing | Solar cells, IR optics, substrates | Export restrictions; small global output |
| Indium (In) | Byproduct of tin and zinc smelting | InP semiconductors, optoelectronics | Supply limited to a few smelters worldwide |
| Tantalum (Ta) | Conflict minerals from Africa, Australia | Diffusion barriers, capacitors | Conflict mining issues; geopolitical risk |
| Tungsten (W) | Mined in China, Russia, Africa | Vias, contacts, interconnects | Concentrated in China; substitution limited |
| Rare Earths | China, U.S., Australia | CMP polishing powders, lasers, magnets | China controls >80% of refining |
From Quartzite to Metallurgical-Grade Silicon
Quartzite (SiO2) is reduced in large electric arc furnaces with carbon sources such as coke, coal, or charcoal. The process produces metallurgical-grade silicon (MG-Si) at ~98–99% purity. This intermediate step is energy-intensive, often requiring more than 11–13 MWh of electricity per metric ton of MG-Si produced. Carbon emissions are significant due to the use of reductants, making MG-Si production a major focus of decarbonization efforts.
- Inputs: Quartzite, carbon (coke, coal, charcoal).
- Process: High-temperature reduction in submerged arc furnaces.
- Outputs: Metallurgical-grade silicon (~98–99% pure), with impurities of Fe, Al, Ca.
- Applications: Aluminum alloys, silicones, and as the precursor to semiconductor-grade polysilicon.
- Strategic Notes: Production is concentrated in China, Brazil, and Norway; energy source determines carbon footprint (hydro vs coal).
Strategic Risks
- Geographic Concentration: Many critical raw materials (Ga, Ge, rare earths) are dominated by single-country supply chains.
- Byproduct Dependency: Elements like Ga, In, Ge are not mined directly but as byproducts, limiting flexibility in scaling production.
- Conflict Minerals: Tantalum, tungsten, and tin are tied to regions with conflict and poor labor practices, raising ethical sourcing challenges.
- Environmental Costs: Quartzite-to-MG-Si refining and rare earth mining have high carbon and ecological impacts.
FAQs
- What is the most important raw material? – Quartzite, since silicon is the base for most semiconductors.
- Why are Ga, In, and Ge considered high-risk? – They are produced only as byproducts, making supply inflexible and prone to bottlenecks.
- Do rare earths go into chips? – Not directly, but they are essential for polishing, lasers, and fab equipment magnets.
- Which country dominates raw material refining? – China, especially in gallium, germanium, and rare earths.
