Semiconductors impact our everyday life through every single electronic device we use. 

As the IoT applications continue to grow at an accelerated rate, the demand for ever-more efficient devices keeps rising.

Canatu CTO Ilkka Varjos spoke about how Canatu can help improve yield and throughput of high-volume semiconductor manufacturing with its CNB free-standing film membrane.

What is the key trend that is reshaping the semiconductor industry?

For half a decade, the semiconductor industry has been driven by Moore’s Law aimed at doubling the transistor density on a wafer every two years. 

A higher density of transistors on a wafer means more efficient processors and memory chips enabling better electronics devices for the consumers.

Keeping up with the pace of development has however become increasingly difficult.

Therefore, the industry has been developing extreme-ultraviolet lithography (EUV) technology, a wafer exposure technology that uses extreme ultraviolet wavelengths to improve resolution and enable the production of wafers with transistor node sizes of 7nm and below. 

Adoption of the EUV lithography is a key enabler of Moore’s Law continuity in the future.

What is the key challenge of the EUV lithography technology?

One of the key challenges in high-volume semiconductor manufacturing is to print ever smaller features without any defects. Very small particles on a photomask (reticle) can lead to errors on the wafer. To overcome this challenge, sophisticated protection for the patterned photomask that maintains EUV power is needed.

What is EUV pellicle?

A pellicle is a membrane used to protect the photomask from particle contamination during high-volume semiconductor manufacturing while permitting high EUV transmission. It is mounted a few millimeters above the surface of the photomask so that if particles land on the pellicle, they will be out of focus to minimize any printing impact.

What requirements are there for a EUV pellicle?

Fabricating a free-standing membrane that is thin enough to limit the imaging impact while robust enough to survive handling is very challenging.

First and foremost, the material must be highly transparent to the EUV wavelength of 13.5nm light that is absorbed by most materials. The higher the transmittance, the better the output and hence the lower the cost per unit. EUV pellicles based on Canatu CNB free-standing film membranes with 97%T at EUV can improve production efficiency by ~25%, which makes CNB pellicle a critical enabler of high yield and throughput in advanced semiconductor manufacturing.

High transmission requirement is further emphasized by the trend towards increasing source power resulting in higher temperatures. At 600W and above in the current scanner environment, existing options will begin to deteriorate.

In addition to high transmission and heat resistance, low flare is required to print features with extreme preciseness without pattern distortion. Finally, the EUV pellicle must meet stringent chemical and mechanical requirements to withstand the EUV scanner environment.

What kind of research have you done?

Since 2015, Canatu has collaborated with Imec, a world-leading research and innovation hub in nanoelectronics and digital technologies, to develop CNB -based EUV pellicles.

CNB -based pellicles have been mounted on reticles and exposed in the NXE:3300 EUV scanner at Imec, demonstrating the successful fabrication and scanner handling of full-field CNB -based pellicles. The tested CNB -based pellicles had a single-pass EUV transmission of up to 97%. The impact on imaging was found to be low and correctable.

Future work will focus on achieving acceptable lifetimes for high volume manufacturing of CNB pellicles in scanners.

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Are there any other applications that could benefit from the CNB freestanding films in the future?

We see great potential in EUV and X-Ray applications that require extremely high transparency combined with stringent mechanical, thermal and chemical properties.

There are many projects going on in this area, for instance, we are currently working with the European Space Agency (ESA) to develop X-Ray optical filter for a satellite.* Some more “down to earth” applications are in mass production development already.

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Will CNB be the next great breakthrough technology, the ‘new Moore’s Law’?

In my view, Carbon NanoBuds (CNBs) have huge potential to become the next great breakthrough technology that enables a whole new semiconductor industry and better electronics devices for all.

As the EUV lithography technology becomes the norm for producing ultra-high pitch patterning on wafers, CNB will make an impact, directly or indirectly, on every person’s life on this planet. For me, that is the true sign of a carbon age.

*The contract will be carried out under a program of and funded by the European Space Agency.