However, this crisis has led to a flurry of innovation and revolutionary new approaches for semiconductor design and operating principles, enabling new ways to improve performance.¹

A key ingredient in this transformation involves the use of new materials, compounds, and control over material properties as part of the device design. The use of novel materials and their manipulation, raises the need for corresponding analytical and metrological techniques for process control. One such technique is Raman spectroscopy, which is already recognized as a high-end metrology solution in the petrochemical and pharmaceutical industry for both qualitative and quantitative analysis². Nonetheless, to date, its uptake by the semiconductor industry has been limited to laboratory applications. Thanks to technological improvements in all key components used in this approach – from ultra-stable laser sources, high-end filters and low-noise detectors, this 90-year-old technique is now becoming a promising and flexible metrology technique for use in high-volume semiconductor fabrication.  

Raman Spectroscopy

Raman spectroscopy (RS) can be used to investigate the vibrational structure of materials and molecules in a non-destructive manner. This is accomplished by measuring the energies of inelastically scattered light from the target of interest. Raman-active materials have a characteristic ‘fingerprint’ in their Raman spectrum, which can be used to identify them as well as study their physical properties. Furthermore, different molecular structures and crystal phases typically give rise to completely distinct Raman spectra, allowing easy identification and differentiation.

RS provides access to extremely diverse material characterization tasks, including stress/strain measurements, defectivity, residue detection, composition and activated doping levels. However, this technology cannot be trivially adapted for in-line, high-volume manufacturing (HVM): RS is typically slow, requires frequent calibrations and easily affected by environmental conditions such as acoustic and vibrational noise and temperature fluctuations. This is where NOVA Elipson™ makes the difference – offering fast, ultra-stable, self-calibrated and fully automatized RS-based metrology.

NOVA Elipson ™ for in-line Raman Measurements

The NOVA Elipson™⁴ is a high end in-line metrology tool, bridging the chasm between lab and fab metrology and bringing Raman Spectroscopy to high volume manufacturing. It combines several unique design features to provide accurate and flexible measurements that can be adapted to monitor a range of material properties – for R&D and HVM ⁵.

The platform allows a range of excitation wavelengths from the UV to visible and has diagnostics to continually monitor the laser output wavelength and power. The laser is coupled into the system via a high precision fiber-dock station, making on-site servicing straightforward.

Combination of multiple wavelengths allows Nova Elipson to create Z-sensitive profiles of various material properties – such vertical strain distribution or poly Si crystallinity and grain size along high aspect ratio geometries.

One of the challenges of Raman measurements is that the scattered signal is extremely weak. Furthermore, the wavelength of the Raman signal is often extremely close to the exciting laser line, causing a significant challenge of efficiently filtering out the laser line from reaching the detector. The entire design of the Nova Elipson^TM is built around these challenges, offering fast Raman detection at a very broad detection range for all excitation wavelengths. Finally, as stated, the tool is designed for seamless, automatic, ongoing calibration protocols, satisfying the stringent precision requirements of the fab environment.

Where spatially-resolved measurements are required, particularly for mapping local regions, the NOVA Elipson^TM can be used for Raman microscopy with a sub-micron spatial resolution. This way, localized properties within (e.g.) a single region of a memory cell can be identified and the spectral information used for process control.

The Future of Fab Material Metrology

Historically, fab in-line HVM metrology solutions have been predominantly focused on dimensionalcharacterization. With the increasing diversity and complexity of materials used in the fabrication process and the nuanced control over their properties, material metrology and process control are soon becoming prevalent. This new arena presents an extremely diverse set of metrology needs, to which the NOVA Elipson^TM offers a flexible, fast, non-destructive and fully-automatized solution.

NOVA Elipson^TM has demonstrated high-end characterization capabilities for a broad set of use cases. These include logic applications – e.g. characterizing stress\strain, composition, active doping and defectivity and material residue identification in the transistor module. A similarly broad set of applications exists in the memory market, characterizing crystal phases and distinguishing between amorphous, poly-crystalline or crystalline Si, phase in emerging memory materials and induced strain. As this tool proliferates into the market, additional use cases are continuously identified and developed, further extending the potential applicability of RS for fab metrology.

References and Further Reading 

1. Lambrechts, W., Sinha, S., Abdallah, J. A., & Prinsloo, J. (2018). Extending Moore’s Law through Advanced Semiconductor Design and Processing Techniques. CRC Press.
2. Paudel, A., Raijada, D., & Rantanen, J. (2015). Raman spectroscopy in pharmaceutical product design. Advanced Drug Delivery Reviews, 89, 3–20. https://doi.org/10.1016/j.addr.2015.04.003
3. Khatibi, S., Ostadhassan, M., & Aghjanpour, A. (2018). Raman spectroscopy : an analytical tool for evaluating organic matter Raman spectroscopy : an analytical tool for evaluating organic matter. Journal of Oil, Gas and Petrochemical Sciences, 2(1), 00007. https://doi.org/10.30881/jogps.00007
4. NOVA Elipson, Nova, (2021), https://www.novami.com/nova-product/nova-elipson/, accessed 20^th January 2021
5. Schmidt, D., Cepler, A., Oren, Y., & Fishman, D. (2021). In-line Raman spectroscopy for stacked nanosheet device manufacturing. Proceedings Volume 11611, Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV;116111T 2021) https://doi.org/10.1117/12.2582181

Despite her busy schedule, we managed to catch Dr. Daphna Peimer on a rare break from her daily race to talk about career, academia, success, and some words of wisdom for female students.

First, let’s talk about science! What is your field of study?

In 2001, I graduated with a bachelor’s degree in physics and computer science from Bar-Ilan University. I then went on to pursue a master’s degree in theoretical astrophysics at the Hebrew University, which I completed in 2005, and in 2015 I completed my doctorate at Tel Aviv University in the field of particle physics.
My Ph.D. focused on searching for a new long-lived elementary particle. Based on particle accelerator data from Stanford University, I was looking for proof of the existence of a particle that could make up the dark matter in the universe. The specific “signature” I was looking for is that of a particle that breaks down into material from the standard model after a relatively long time.

Out of left field- Who is your everyday hero?

During my PhD studies, I worked as a teaching assistant in a physics course for engineers in the Faculty of Engineering at Tel Aviv University. While I was solving an exercise on the whiteboard, a lizard suddenly fell from the air conditioner hatch above me- right next to me on the podium. I froze in place while the lizard ran to the corner. Out of 40 students in the room, there was only one female student, and she sat in the front row. She noticed my distress and asked if the lizard was interfering with my ability to continue the lesson. I replied in the affirmative, and in response, she got up, picked the lizard up with her bare hands, and released it outside the window. I’m still in shock- and she’s my hero!

Please introduce us to a day in the life of Nova

I arrive at the office around 8 a.m., look at the meeting schedule and plan my daily tasks accordingly. I work on designing, developing, and researching algorithms to help Nova customers accurately and efficiently measure the latest developments. In between, there are meetings with team members, with the algorithm group, Application engineers, software developers, etc. Twice a week I start the day with a Pilates or yoga class at Nova. Over the past year, we had those lessons online, plus cool mid-day Yoga breaks, which I love. There are often surprises and tasty treats waiting for us in the kitchen or on our desks, and of course, one of the challenging daily tasks is to choose what to order for lunch.

Tell us about a significant contribution you made to product development

When I joined Nova, a member of my team started developing a unique algorithm. Coincidentally, I had the technical tools to develop a model that made the algorithm accessible to any application engineer group. This accessibility has helped refine the algorithm and make it efficient and central to many Nova customers.

Do you feel that we have broken the glass ceiling or that there is still room for improvement?

When there is an adequate representation of all gender and ethnic groups in science, politics, economics, and all centers of power, and when the wage gaps between them are reduced, we will say that we have reached the goal. I am happy to live in a time when awareness of equality is growing, and the world is moving in a positive direction, but there is more to strive for.

Do you have any tips for young female students or those considering a career in engineering?

I taught at the Faculty of Engineering for 4 years. Throughout the period, I was delighted to see a large representation of female students in the faculty, all of them smart, dedicated, and full of promise. It is vital that students are aware of their abilities and the perseverance and ambition they demonstrate and be proud of their achievements.
I once read a study about how men dare to ask more questions than women during classes and that academic instructors tend to answer men first and prioritize men over women when granting speaking permission. I tested this out for myself, and to my surprise, I discovered that this is true for me. Since then, I have made a conscious effort to correct myself and permit female students to speak. Female students can also check if this dynamic is the same in their classes and try to consciously increase the frequency of their questions, making themselves heard to move ahead and understand the material even more.

After many years in academia and the industry – what is the importance of connecting the two worlds?

In industry, as in academia, there is an advantage to creativity and innovation. Sometimes we look for the next original idea, even when it seems like everything has already been tried and tested. That’s why at Nova, we like to bring in lectures by members of the academia – you never know what will ignite the inspiration for the next idea and collaboration.
The process of finding my first job towards the end of my studies was quite long and frustrating. Despite the directions and tools given to us in the workshop towards the end of my Ph.D. studies, I had no concrete proposals or connections in the industry world. Recruitment events and guest lectures at the university from companies like Nova can significantly help students transition from advanced degrees to industry and exposure to jobs where they can leverage the knowledge and tools they have acquired in their studies. It’s important to note that Nova has research teams in various fields such as Physics, Optics, algorithms, and other academic areas. Our work here is highly multi-disciplinary, and we value knowledge from a wide range of domains.

Give me 3 reasons why someone should join the Nova family? 

My first reason would be interesting work in a fascinating and evolving field that affects all of us’ daily lives.
Second, Nova has a pleasant and pampering work environment with high-quality, talented people who cheer you on. The general atmosphere allows for a healthy balance between work, family, volunteering, and sports. As a bonus, one can connect with co-workers in Taiwan, Japan, China, Korea, and the US and learn about the cultures, holidays, and mentality of many countries worldwide.
And Third? The sparkling water fountain.

If you were not an engineer, what would you choose to be, and what is the field of research that intrigues you?

If I were not a physicist, I would have been a dancer. It was my dream from a young age, but it didn’t materialize… Many research areas intrigue me, including genetic engineering, psychology, and astrophysics. So, the sky is the limit, and who knows? Maybe a second Ph.D. is in my future!

Zohar, let’s start with you. What magic is brewing in the semiconductor manufacturing industry that’s changing the way we talk about semiconductors?

“The fact that semiconductor manufacturing is enabling breakthrough technologies and powering various cutting-edge digital devices, is definitely changing things.  The industry’s growth trajectory holds immense potential because of emerging new technologies like autonomous driving, AI, 5G, IoT, and more. Though the shape and dynamic of the semiconductor industry have changed dramatically, driven by headlong growth demand for IC manufacturers across the globe, the journey is not an easy one.  These IC manufacturers operate in a highly challenging and competitive environment, where they need to provide their solutions to the cadence of Moore’s law—enhancing their technologies and bringing solutions with better performance to the market every two years.”

With things moving so fast and with so much competition, do you think it’s possible to keep up the magic?

“To keep up the momentum in this rapidly changing landscape, semiconductor manufacturers need to achieve shorter development cycles, faster time-to-market, and higher product yields that collectively contribute to rapid product launches. But that is easier said than done.

And that’s precisely where Nova is moving the needle. As an international company, Nova specializes in process control solutions for the semiconductor manufacturing industry. Deployed with the world’s largest integrated-circuit manufacturers, Nova’s novel technologies provide semiconductor manufacturers with the right process insight and clarity required to boost process performance, product yields, and time to market. Nova is delivering continuous innovation by providing advanced process control metrology solutions that present a unique combination of dimensional metrology (for measuring critical dimensions) and materials metrology (for measuring material properties).”

Shay, what would you say is Nova’s secret of innovation?

“I would say it’s that Nova provides customers with advanced modeling algorithms combining physical modeling with machine learning and big data within both integrated and stand-alone configurations. This enables them to gain deeper insight and faster time to solution, throughout the entire R&D and manufacturing processes.

Nova’s ingenious metrology solutions are based on numerous advanced technologies in various fields of expertise, including Optical Scatterometry, X-ray Photoelectron Spectroscopy (XPS), X-ray Fluorescence (XRF), Raman spectroscopy, scatterometry modeling software and high-performance computing.”

We have unique hardware solutions combined with an algorithmic suite which is both physically and mathematically based, using artificial intelligence and machine learning. 

Zohar, how do you determine what your customers want?

“Attaining a deep understanding of our customers’ challenges and processes is really important to us. That’s why our technology and product experts invest a significant amount of time collaborating with customers, at every phase, in order to understand what challenges face the customer. Once we understand the challenge, we can move on to developing the solution.  

During the manufacturing process, our solutions enable our customers to see critical parameters that influence the device performance. These have a high correlation to the yield at the end of the line. As a result, with our advanced process control, manufacturers can better control the process and eventually achieve high yield.”

They say belief informs action. Shay, what do you think is one of Nova’s core beliefs that inform action?

“We firmly believe in innovation and provide solutions that take the off-beat path of technology. We strive to create new channels of information and additional sources of data, challenging the preconceived standards in the industry. This is then combined with our unique modeling solutions, which include understanding the sample, structure, process, and more. Our strong mathematical modeling of machine learning and big data enables the customers to analyze and utilize the data, make use of multiple measurements, and implement it all in smart infrastructure.”

Zohar, Can you put your finger on what characterizes Nova’s innovators DNA?

 Nova’s unparalleled capabilities can be best explained through a customer success story that involved one of the largest manufacturers in the world. The client approached Nova for a solution that was not available before, both in terms of information content and output. With its unique approach, Nova introduced a completely new solution in terms of hardware and algorithms and offered the client a quick turnaround time to develop models and get insight into the process with a limited need for destructive measurements. This solution helped the client to accelerate its R&D cycle and solved various critical applications. Moreover, the solution provided the client with insights into their process development and faster response time.

Clearly, the uniqueness of Nova stems from its ability to innovate and execute anything in a channelized manner. Also, the company invests nearly 20 percent of its revenue back in the R&D to improve the existing solutions and develop unique technologies and solutions for its customers. Similarly, the collaborative approach and partnership with its clients in the semiconductor manufacturing space is something that has made Nova a global company that is trusted and appreciated.

Shay, what makes Nova so proud about success stories like this?

Success stories, like this one, are testament to the value and innovation Nova brings to the table. With team work firmly embedded in its DNA, and an understanding that complex problems require multilayered solutions, Nova develops future technologies in multidisciplinary teams, thinking outside the box. With increasing demand for semiconductor technology across many verticals ranging from 5G in automotive to smart manufacturing, Nova, with its unique set of technologies and solutions, looks forward to bringing next-generation solutions to the industry. We see a lot of progress in process control and metrology and we challenge ourselves to redefine the limits of what can be achieved in this domain.