Lithography, a new milestone

In Multibeam's view, today can be regarded as a milestone in the global semiconductor industry because they launched the MB Platform today, the world's first multi-column electron beam lithography (MEBL: Multicolumn E-Beam Lithography), which can make chip factories better.

According to reports, its new lithography system (essential for printing patterns on chips) is a system designed for mass production. The fully automatic precision patterning technology will be used for rapid prototyping, advanced packaging, high-mix production, chip ID, compound semiconductors and other applications. Multibeam said that the company's newly released platform will revolutionize electron beam lithography (EBL) with new productivity advantages, while achieving high resolution, fine features, wide field of view and large depth of field.

But in fact, Multibeam's technology seems to have been abandoned by the industry? Let's see what kind of waves they want to make.

Looking at current chip production, there are three main schools of thought to choose from, namely the now widely used ASML EUV type equipment, nanoimprinting and multi-beam direct writing.

Among them, we have already introduced EUV lithography technology extensively before, so we will not go into it in depth. But we need to understand that with the miniaturization of chip technology, the development and production costs of lithography machines, and even masks and photoresists will become obstacles to the continued advancement of lithography technology. However, after decades of research and development and advancement, this has become the mainstream production method.

Nanoimprint lithography (NIL) is an advanced imprinting process for creating tiny features on a device.

Since the 1990s, NIL has been in the R&D stage similar to the stamping process. Initially, the electron beam system forms a pattern on the template according to a predefined design. Then, a resist is applied to a separate substrate. The patterned template is pressed against the substrate to form a pattern on the substrate with feature sizes as low as 5nm or even smaller. In terms of application, NIL is divided into two camps: memory and others. Among them, Canon has been developing NIL systems designed for the production of NAND flash memory and other types of memory for some time.

However, NIL faces challenges such as overlay, defect rate and yield, which hinder NIL from becoming a mainstream technology. "Imprint lithography is a contact patterning method. Imprint lithography is used for applications that are tolerant to defects," analysts stressed.

Multi-beam direct writing is another option. Like nanoimprinting, this is not a new technology.

This direct-write lithography technology was developed by IBM as early as the 1980s. In principle, multi-beam direct writing uses an accelerated electron beam to create features smaller than 10 nanometers on a substrate coated with an electron-beam-sensitive photoresist. Exposure to the electron beam changes the solubility of the photoresist, making it possible to selectively remove exposed or unexposed areas of the photoresist by immersing the photoresist in a developer.

Direct-write technology is attractive because it does not require expensive photomasks. But the throughput of single-beam electron beam lithography is too slow and too costly for volume IC production. Analysts also bluntly say that the real problem with direct writing is throughput. Direct-write lithography, even with hundreds of thousands or even a million beams, is too slow for wafer lithography.

As a result, single-beam direct writing tools can only be used for niche applications such as compound semiconductors and photonics. Early players including KLA and Mapper have either exited or been acquired.

But Multibeam is still confident. With MEBL technology, they hope to revive this decades-old technology. Multibeam's founder said it is like having the speed of a printing press or 3D printer, but with the customized flexibility and adaptability of a pencil.

Multibeam can make some parts of chip manufacturing 100 times more productive than existing systems, David K. Lam, Multibeam’s chief executive and chairman, said in an interview.

In Multibeam's view, this is a game-changing device. According to reports, in order to solve the throughput problem in the production process, Multibeam uses multiple micro-columns that can run individually and in parallel and are equipped with advanced control systems.

According to reports, the company's team designed the platform from the beginning to achieve mass production, and there are more than 40 patents protecting these innovations. In addition to the multi-column vector writing architecture that improves productivity, accuracy and speed, the platform also provides automatic wafer loading and alignment from the wafer box to the exposure process in the system.

In addition, an automatic vacuum recovery system as well as a rapid column replacement process and calibration technology optimize uptime. Advanced automation features reduce operator requirements and further increase system cost of ownership.

As a maskless lithography solution, the platform also offers additional benefits. While developing an optical mask can take weeks, the MB platform can produce a design in just hours. This provides manufacturers with greater IC design freedom while reducing costs and accelerating time to market.

To further increase design flexibility, the platform leverages technology from EDA leader Synopsys to generate write recipes, enabling customers to achieve the most complex patterns. With a powerful built-in data preparation system developed jointly with Synopsys, the system can write the chip layout directly onto the wafer without a mask.

“We basically reinvented electron-beam lithography,” Lam said. “We were well aware that it had been ignored for decades. People thought it was too slow. I was lucky if I wasn’t laughed at. However, the team really put in a lot of effort on all fronts to develop capabilities that [competing] optical techniques just couldn’t achieve.”

Ken MacWilliams, president of Multibeam, said specialized silicon helps chip designers get products to market faster. Through packaging innovations, chip design companies such as Nvidia can put two chips in the same package and let them work together as if they were one chip. This helps improve performance.

Finally, due to its small footprint, the system has lower power requirements and requires less fab space. Its modular design allows modules to be easily added as new applications or higher volumes are needed. In addition, it is completely self-contained and does not require a special environment, further reducing costs. The system is available in 150mm, 200mm and 300mm configurations.

At present, Multibeam has not disclosed the highest resolution physical definition it can achieve, nor how many beams can be independently operated in the MB platform. However, they said that its single beam runs at 5kV. The company also claims that its MB platform has 10 times higher definition than optical lasers and 100 times higher depth of focus and field of view than optical lithography.

“We are excited to launch the MB Platform and proud to ship our first production system to SkyWater,” said Lam. “Growth in the semiconductor industry continues to be driven by exciting new applications, with advanced lithography enabling endless innovation. At the same time, markets such as AI and edge computing are growing rapidly, driven by specialized silicon and advanced packaging, and manufacturers’ priorities are fast learning cycles and cost-effective, seamless transitions to production to accelerate time to market. For these emerging markets, the MB Platform provides a complementary lithography solution and expands the range of lithography options available to IC leaders,” continued Lam.

While EBL is valued for its patterning capabilities, low throughput limits its ability to transition emerging applications from R&D to production. As MB platforms evolve, new applications emerge with technical, economic, and time-to-market requirements that can be addressed with non-mask-based lithography solutions.

“This development reinforces our belief that our EBL system, redesigned for increased productivity, can enable advanced-node applications for the first time,” said MacWilliams. “The performance benefits are particularly dramatic in advanced packaging, where our system can improve inter-die power as well as bandwidth and latency. This helps drive a new technology inflection point that the industry is beginning to call ‘advanced integration’ – where new inter-die interconnects can achieve performance comparable to on-chip interconnects.”

“We are proud to enable this transition with our production-proven lithography solutions and believe our systems will help chipmakers capture profitable new market opportunities,” added MacWilliams, further noting that specialized silicon helps chip designers get products to market faster. Through packaging innovations, chip design companies such as Nvidia can put two chips in the same package and have them work together as if they were one chip. This helps improve performance.

“We have to acknowledge that Moore’s Law is over,” Lam said. “ASML’s roadmap shows transistor density improving by a factor of 0.7 at best over the next 12 to 14 years. So the only way to really get gains is to stitch more chips together. So that puts a lot of pressure on advanced packaging. We have an interesting chart that says, to our credit, Moore’s Law has increased transistor density by a factor of 500 over the last 20 years. Advanced packaging has only increased it by a factor of 15.”

What do you think about the future of Multibeam?

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