Intel: Our fabs can mass produce silicon qubit devices

If conventional silicon manufacturing processes can be repurposed, it could help create practical quantum systems

Updated Intel and QuTech claim to have created the first silicon qubits for quantum logic gates to be made using the same manufacturing facilities that Intel employs to mass produce its processor chips.

The demonstration is described by the pair as a crucial step towards scaling to the thousands of qubits that are required for practical quantum computation.

According to Intel, its engineers working with scientists from QuTech have successfully created the first silicon qubits at scale at Intel's D1 manufacturing factory in Hillsboro, Oregon, using a 300mm wafer similar to those the company uses to mass produce processor chips.

QuTech is a partnership between Delft University of Technology (TU Delft) and the Netherlands Organisation for Applied Scientific Research (TNO) focused on quantum computing research.

The result is a process that could fabricate more than 10,000 arrays with several silicon-spin qubits on a single wafer with greater than 95 percent yield, Intel claims, stating that this is significantly higher in both qubit count and yield than current processes used to create qubits.

Quantum computing is still at a very early stage of development, but many of the architectures that researchers are experimenting with require a large number of qubits to ensure reliability. Also key is gate fidelity, a measure of how free from error individual qubits are.

Being able to manufacture qubits at scale is therefore a vital step, and if conventional silicon manufacturing processes that have been developed and tuned by chipmakers such as Intel over many years can be repurposed for this, it will be a stride towards scaling to the thousands of qubits that are needed for practical quantum systems. This is essentially what Intel and QuTech are claiming to have demonstrated.

"Our research proves that a full-scale quantum computer is not only achievable but also could be produced in a present-day chip factory. We look forward to continuing to work with QuTech to apply our expertise in silicon fabrication to unlock the full potential of quantum," said Intel's director of Quantum Hardware, James Clarke.

The research was published in the journal Nature Electronics. The abstract for the article states that the potential of using industrial semiconductor manufacturing for quantum gates has driven the development of quantum computing in silicon quantum dots, but that fabrication has so far relied on electron-beam lithography processes that suffer from low yield and poor uniformity.

Specifically, current semiconductor qubit chips are typically fabricated in cleanrooms using tools that are optimized for flexible design changes and fast turnaround, but compromise on reliability, according to QuTech, whereas industrial semiconductor manufacturing processes are optimized for reliability.

"Industrial manufacturing techniques are different from the techniques that are typically used to fabricate such quantum dot samples," said QuTech's Anne-Marije Zwerver, PhD researcher and first author of the report.

According to the report itself, a key question was whether the reliable but strict design rules of patterning in industrial semiconductor manufacturing could be used to produce suitable qubit device layouts, and whether the coherence properties of the qubits would survive the processing conditions, such as chemical mechanical polishing, which silicon wafers undergo during commercial manufacturing.

However, although this is regarded as a significant breakthrough by Intel and QuTech, it appears that much more research work needs to be done, and we shouldn't expect to see silicon qubit devices for anything other than development rolling off an Intel production line any time soon.

We contacted Intel and QuTech with regards to the next steps for this technology, and will update this article if we get a response.

The report states that although there are significant challenges to overcome to engineer out defects and improve qubit performance and scalability, the full 300mm device-integration line established by Intel and QuTech will allow them to run a high volume of experiments to accelerate development compared with conventional fabrication methods.

"The compatibility of silicon spin qubits with fully industrial processing demonstrated here highlights their potential for scaling and for creating a fault-tolerant full-stack quantum computer," the report concludes.

Intel last week disclosed that it is to deliver quantum computing testbed equipment to the US Department of Energy's Argonne National Laboratory (ANL) where it will slot into a real-world quantum system being constructed there. ®

Updated on April 20, 2022 at 1253 BST to add

In response to our queries, Ravi Pillarisetty, Quantum Device Engineer at Intel, told us that the ability to mass produce silicon qubits will be used for development by enabling a high volume of experiments and statistical data collection, but the expectation is that this will eventually lead to commercial products.

"We believe that for any commercial application we will need a chip with millions of qubits. We envision one day being able to build a system to such scale by integrating our qubit process together with the advanced interconnect and circuit design infrastructure associated with semiconductor manufacturing," Pillarisetty said.

Technological innovations in the semiconductor industry can "take a long time to bloom," according to Intel, indicating that quantum technologies are at least 10 years away from having an impact.