Series: "Japan's Vision for Becoming a New Resource Superpower Through Process Innovation" — Part 3 ← Previous: [The Future Diamond Semiconductors Will Change]

"If diamond semiconductors are so amazing, why aren't they widespread yet?" The answer is simple: the fact that diamond is the world's strongest material is itself the biggest barrier.

The standards required for gem-grade diamonds and semiconductor-grade diamonds are worlds apart. In this installment, we'll look at the three walls blocking mass production, the Japanese ingenuity trying to break through them, and some surprising applications beyond semiconductors.

The "Three Walls" Blocking Mass Production

Wall ① Size: Wafers Won't Grow Large Enough

To manufacture semiconductor chips cheaply and in large quantities, you need to pattern thousands of chips at once on a large disk (wafer) 15–30 cm (6–12 inches) in diameter. That's standard practice with silicon, but with diamond it's an enormous challenge.

  • Current state: The largest single-crystal diamond that can be grown at one time is limited to just a few millimeters to about 1 cm square
  • Mosaic bonding: A technique of arranging small diamond tiles and joining them is under development — but crystal misalignment at the "seams" makes them prone to cracking
  • Target: Practical use requires high-quality wafers of at least 2 inches (about 5 cm), ideally 6 inches or more

Wall ② Hardness: Processing Is Nightmarishly Difficult

Diamond is the hardest substance in the world. That's ideal as a material, but for anyone trying to machine it, it's a pure nightmare.

  • Can't be sliced easily: To make a semiconductor, the crystal must be sliced thin and polished to atomic-level flatness — but there's a physical law that says "only diamond can cut diamond"
  • Solutions: Laser machining and plasma polishing are being researched, but they're still far from matching silicon's speed and cost

Wall ③ Electrical Control: N-Type Is Hard to Make

To function as a semiconductor, two types must be combined: "P-type (positive)" and "N-type (negative)."

  • The N-type problem: Diamond's crystal lattice (imagine a jungle gym made of carbon atoms) is packed extremely tightly, and trying to force in phosphorus atoms — which are slightly larger than carbon — distorts and damages the crystal
  • Current state: Japanese research teams are making progress in producing clean N-type diamond, but stable mass production in a factory setting still faces a high hurdle

And looming over everything at the end is cost. Current diamond semiconductor wafers are priced at thousands to tens of thousands of times the cost of silicon wafers. Whether that price can be brought down from satellites and military radar to something usable in smartphones and EVs is the key to becoming a resource superpower.

A Shift in Thinking: Making Diamond That Doesn't Need to Be Machined

Here's where an interesting idea emerges. "If it's too hard to cut, just grow it as a thin film from the start — no cutting needed."

Manufacturing methods that involve "no cutting, no grinding" are being developed at a furious pace, led primarily by Japanese research institutions.

① The "Crêpe Method": Heteroepitaxial Growth

Instead of growing a bulk crystal and then slicing it, this approach grows a thin layer of diamond on top of a different base material — like spreading crêpe batter.

  • How it works: A sapphire or iridium disk is used as the base, and diamond film is grown on it by blowing in gas
  • Advantage: The result is already a "thin disk" from the start, eliminating the slicing step (and the kerf loss that comes with it)
  • Japan's achievement: Saga University and Orbray, among others, have succeeded in producing 2-inch (approx. 5 cm) diameter wafers using this method

② The "Peeling a Sticker" Method: Smart Cut / Lift-Off

This technique involves "peeling off" just a thin film from a diamond base that has already been grown.

  • How it works: Ions are implanted into the surface to create a "easy-to-peel layer," new diamond is grown on top, and then the film is peeled away like a sticker
  • Advantage: The expensive base (seed crystal) is not consumed and can be reused (copied) many times, dramatically reducing costs

③ The "Mold-Casting" Method: Selective Growth

Diamond is grown only where it's needed.

  • How it works: A mask is placed on the substrate to block growth in unwanted areas, and crystal growth occurs only where circuitry is required
  • Advantage: The result is already close to the final device shape from the start

That said, one final step — atomic-level planarization (polishing) — simply cannot be avoided. Here, a new technology is emerging: instead of conventional abrasive polishing, plasma (reactive gas) is used to chemically dissolve and flatten the surface.

The weakness of "too hard to machine" is rapidly approaching the point where Japanese technology may consign it to history — and we're genuinely at that stage now.

Not Just Semiconductors: The Four Major Domains of Diamond Applications

If diamond is set to transform the "brain of industry" (semiconductors), its other applications will dramatically evolve the "body of industry" — infrastructure, medicine, the environment, and manufacturing. Beyond being "hard," properties like "harmless to the human body," "resistant to chemicals," and "transparent to virtually all light" come into play.

① Environment & Water Treatment: The Ultimate Electrode for Turning Contaminated Water into Clean Water

This is seen as the next biggest market after semiconductors. When boron is mixed into diamond and an electric current is applied (BDD electrodes), powerful oxidizing agents are generated that break down contaminants in water.

  • PFAS decomposition: The "forever chemicals" currently causing problems worldwide can be completely broken down and rendered harmless
  • Chemical-free water purification: Industrial wastewater and river water can be powerfully sterilized and purified without chlorine or other chemicals

If Japan can package this technology, it could become an environmental powerhouse by exporting "diamond water purification infrastructure" to countries suffering from water scarcity and contamination.

② Medicine & Biotech: Cancer Treatment and Artificial Organs

Because diamond is carbon, it has the rare property of not being recognized as a foreign substance by the human body (high biocompatibility).

  • Nanodiamond: Anticancer drugs are attached to ultra-tiny particles and introduced into the body. Normal cells are bypassed, and the drug is delivered only to cancer cells — a drug delivery system with enormous promise
  • Artificial joints & dental implants: Harder than titanium or ceramic and more compatible with bone. Implants that are virtually wear-free for a lifetime become possible

③ Machining & Manufacturing: A Revolution in "Cutting Edge" Performance

What if diamond tools — currently expensive and limited to specialized uses — could be mass-produced to the price of ordinary steel tools?

  • Every tool goes diamond: From factory lathes to home DIY
  • A dramatic shift in production efficiency: Chipping and tool replacement drop sharply, and the speed of machining aircraft and automotive parts increases several to tens of times over. The entire cost structure of manufacturing changes

④ Space & Optics: The Ultimate Window and Laser

Diamond transmits virtually all light, from ultraviolet to infrared.

  • High-power laser cutting machines: Glass lenses shatter under powerful lasers, but diamond lenses can withstand them. Devices capable of cutting through thick steel plates in an instant become reality
  • Windows for spacecraft and deep-sea submersibles: Withstands extreme pressure and radiation while maintaining a clear view. Usable in extreme environments like Venus exploration or 10,000 meters below the ocean surface

The "Diamond Age" That Mass Production Will Bring

If artificial diamonds can be mass-produced cheaply, here's how life will change.

Field Today (expensive and limited) Future after mass production
Water Purified with chemicals Harmful substances completely eliminated with diamond electrodes
Medicine Anticancer drugs with side effects Nanodiamonds strike only the affected area
Tools Cemented carbide that wears out quickly Permanent tools that never need replacing
Smartphones Glass cover (shatters) Diamond cover (absolutely unbreakable)

If semiconductors handle "computational power," these applications raise the floor of "physical quality of life." Japan would hold "diamond as a common platform" not just in electronics, but across medicine, the environment, and manufacturing alike.

Coming Up Next

However, this grand vision has one critical bottleneck.

Both titanium smelting and diamond synthesis consume enormous amounts of electricity. As long as Japan remains a country with high electricity costs, no amount of technological prowess will make the economics work — and factories will simply be taken to countries with cheaper power.

In Part 4, we'll look at the "Four Domestic Energy Revolutions" that could solve this most critical vulnerability.

→ Next: [Four Energy Revolutions to Power a Resource Superpower]