Researchers Develop Monolithic 3D Silicon Stacking

Qing Cao and the Monolithic 3D Stacking of Silicon Layers

Monolithic 3D Stacking and the Future of Silicon

For decades, the computing industry has followed a formula of making transistors smaller and packing more of them onto a chip, a strategy that fueled the rise in computing power predicted by Moore’s law. However, as components approach atomic scales, engineers are increasingly running into the physical limits of silicon and the effects of quantum mechanics. A team led by University of Illinois Grainger College of Engineering materials science and engineering professor Qing Cao has demonstrated a new method for stacking multiple layers of silicon electronics directly on top of one another.

Cao explained the shift: “Take something as simple as static random-access memory, which is universal in CPUs and GPUs. Today it takes six microelectronic devices called transistors on a single plane to store one bit of information. With vertical integration, you can distribute them across multiple layers. It’s like replacing a sprawling suburb with high-rises: you get the same functionality, but the spatial footprint is reduced while making communication between layers faster and more efficient.”

The researchers report that their process achieves device yields of 98‒100% while using standard single-crystalline silicon. According to Cao, while vertical integration is beginning to appear in commercial devices, particularly in specialized AI hardware, “monolithic integration is what unlocks the full promise of 3D chips.” Cao noted, “For the first time, we have met the thermal budget of monolithic 3D integration using standard single-crystalline silicon and delivered unprecedented performance.”

Monash University Develops Integrated Valleytronics Circuits

Integrated Valleytronics

Scientists at Monash University have created a tiny new circuit that can generate, direct, and read information carried by light within a single chip. This advance marks a milestone for “valleytronics,” a field that could drive future breakthroughs in faster computing and lower energy consumption. Developed by researchers from the Monash School of Physics and Astronomy, the device uses a quantum property called the “valley degree of freedom.”

Lead author Dr. Chi Li, whose team’s findings were published in Nature Photonics, stated, “Until now, we could generate or detect these signals, but not do everything in one integrated device. What we’ve built is a complete on-chip system that can create, route and read this information with very high precision.” The device relies on ultra-thin materials only a few atoms thick paired with engineered nanostructures. Dr. Kaijian Xing, co-first author and Research Fellow at Monash University, explained that the team developed a practical way to combine these components: “We employ a straightforward stacking approach to integrate ultra-thin materials with metasurfaces, overcoming the technical challenges of direct material growth on photonic structures, and enabling further advances in valleytronics.”

Microsoft Utilizes Majorana 1 for Topological Quantum Computing

Microsoft’s Majorana 1

Microsoft has introduced Majorana 1, the world’s first quantum chip powered by a new Topological Core architecture. It leverages a topoconductor, a breakthrough material that can observe and control Majorana particles to produce reliable and scalable qubits. Chetan Nayak, Microsoft technical fellow, said, “We took a step back and said ‘OK, let’s invent the transistor for the quantum age. What properties does it need to have?’ And that’s really how we got here – it’s the particular combination, the quality and the important details in our new materials stack that have enabled a new kind of qubit and ultimately our entire architecture.”

This architecture offers a path to fit a million qubits on a single chip that can fit in the palm of one’s hand. Microsoft stated this threshold is necessary for real-world solutions, such as breaking down microplastics or inventing self-healing materials. As Microsoft noted, “Whatever you’re doing in the quantum space needs to have a path to a million qubits. If it doesn’t, you’re going to hit a wall before you get to the scale at which you can solve the really important problems.”

TU Delft Observes Quantum Spin Currents in Graphene

Quantum Spin Currents in Graphene

Scientists from TU Delft have observed quantum spin currents in graphene for the first time without using magnetic fields, a breakthrough published in Nature Communications. Quantum physicist Talieh Ghiasi explained, “Spin is a quantum mechanical property of electrons, which is like a tiny magnet carried by the electrons, pointing up or down. We can leverage the spin of electrons to transfer and process information in so-called spintronics devices.”

Previously, detecting these currents required large magnetic fields impossible to integrate on-chip. By layering graphene on a magnetic material, CrPS₄, the researchers bypassed this need. Ghiasi noted, “The fact that we are now achieving the quantum spin currents without the need for external magnetic fields opens the path for the future applications of these quantum spintronic devices.”

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