Background
Clemson University launched a diffractive optics Ph.D. program in 2011 within the Clemson College of Engineering, Computing, and Applied Sciences (CECAS). They brought on board Dr. Eric Johnson, Comporium and PalmettoNet Endowed Chair in Optoelectronics; Professor of Electrical and Computer Engineering and a fabrication expert in diffractive optics; Mr. William Delaney, Research Associate Electrical and Computer Engineering, Manager of the Micro-Photonics Fabrication Facility.
One of CECAS’s primary objectives is to produce diffractive optical elements. This innovative technology was discovered in the mid-eighties and patented in the late-eighties at MIT Lincoln Lab.
First and foremost, CECAS focuses on students pursuing their Ph.D. in optics, electrical engineering, and other disciplines. Mr. Delaney is responsible for guiding them on how to use the equipment and tailor device processes in fabricating devices. Once they achieve their degrees, graduates work in industry, national research labs, and education.
They bring cutting-edge innovations to some of the most renowned organizations in the world, such as Intel, Texas Instruments, Sandia National Labs, MIT Lincoln Labs, Micron Technologies, and Samsung. Clemson University provides excellent value to those building their careers who want to contribute to industry and research. CECAS students receive the necessary skills to make an impact in these areas.
Over the last ten years, the program has graduated more than 15 Ph.D. students, with approximately five currently enrolled.
Casebook Situation
The Clemson College of Engineering, Computing, and Applied Sciences is a research organization for optical, electronic & software devices & systems. These devices and systems are fabricated for private industry and the U.S. Gov’t.
To support project success, process engineers often act like detectives. Gathering as much information as possible is crucial in solving issues. It doesn’t matter if they’re unsure where the problems lie; they’re confident that solid information will lead them in the right direction.
The facility faced some challenges early on. At that time, there was a shortage of experienced microfabrication process engineers, and knowledge of the fabrication industry was limited. Mr. Delaney was hired by CECAS, in part, to oversee the rebuilding of the clean room completely. The room needed to be properly controlled for temperature, humidity, and cleanliness. Clemson hired an experienced contractor from Michigan to work on the clean room, which was certified in July 2014. Over the next few months, the equipment from the previous laboratory was moved to the new one.
Clemson also realized it was vital to consider operational efficiencies relative to non-core production activities. Stage micrometers could have been fabricated onsite because CECAS has the equipment to do so. But the time it would have taken and their inability to certify was a non-starter.
“I would have to send it out to be measured and certified. So, I purchased the certified component off-the-shelf from Applied Image at a fraction of the cost and time of producing it myself. So that’s the real value of Applied Image to organizations like mine.”
“We could do a lot of things. But just because you can do something doesn’t mean you should. For CECAS, even producing simple non-standard components would mean a lengthy process development effort involving reworks, design improvements, and restarts until the process was optimized.”
Instead, CECAS wants to concentrate on its design and fabrication capabilities in making optical devices & systems rather than making metrology pieces for measurement equipment. “Focusing our resources on our core competencies is key to building a sustainable organization.”
About Clemson University
Clemson University is among the nation’s most accomplished public universities. Its students, faculty, staff, alums, and stakeholders hold the highest standards in the world’s classrooms, boardrooms, and beyond. CECAS has fully equipped labs, including the state-of-the-art Fluor Daniel Engineering Innovation Building. Clemson: focused on student experience, research, and transforming lives.
Resolution
CECAS microfabrication lab covers approximately 3500 sq. ft. The lab has full wafer cleaning, wet chemistry equipment, and full fabrication capabilities focused on diffractive elements and simple microelectronics. The lab also has full e-beam & optical lithography capabilities, two dedicated plasma systems for chlorine and fluorine etching used in dielectric & metal ICP plasma etching, and an e-beam evaporator & ALD dielectric coating tools.
Clemson’s metal evaporator is used to put down any metal required for device fabrication. They use the ALD tool to deposit dielectric coatings to insulate electronics or for antireflection coatings for optical devices. Additionally, the team uses dicing saws to cut wafers into any size required for the application after fabrication.
All this equipment variety is a competitive advantage but also creates challenges as it requires advanced metrology. Additionally, their optical microscope needed an upgrade to quickly measure CDs (critical dimensions) for all lithographic, deposited & etched structures. Using the scanning electron microscopes was time-consuming and only worthwhile when the geometries were too small to be measured with the optical microscope.
To overcome these challenges, the team purchased standards from Applied Image to calibrate the optical microscope. These standards helped calibrate their microscopes quickly and train their technicians. As a result, the engineers could measure and get precise numbers for alignment and placement, which was crucial in maintaining process control. It is crucial for Clemson to keep these tools calibrated to ensure their accuracy and efficiency.
sm-6 sm-6p-cg-seccal
Implementation
CECAS aimed to attain accurate and objective measurements based on a standard rather than subjective ones. They turned to Applied Images for the NIST traceable components needed to calibrate its systems. Their micrometers come with NIST traceable calibration standards and are available on multiple substrates. Applied Image has the Chrome-on-glass stage micrometer that meets CECAS’s requirements readily available and in stock.
The college required a part with 10 microns per division to calibrate the reticle on the microscope outfitted with a digital camera. Since the part is readily available off-the-shelf from Applied Image, ordering was fast and easy.
Results
Within the CECAS labs, measuring and identifying any issues is crucial to ensure proper alignment. If the alignment falls below a certain threshold, rework may be necessary. When attempting to position two structures close together, there is a risk of a short circuit (with electrical devices) or (lower diffraction efficiency with optical devices if poorly aligned). Therefore, it is essential to ensure that the alignment meets specifications.
CECAS uses well-established tolerances to maintain process control. While Clemson may have a more traditional approach, with some extra training and thorough inspection, they accomplish the task with great effectiveness.
CECAS can measure device location, alignment quality, defect size, and placement on a sub-micron scale. They can inspect incoming materials to a certain extent using a reticle. However, CECAS lacked reticles in their scope, and much of their work was repetitive from years ago.
Nevertheless, they had the necessary processes and equipment. Mr. Delaney aimed to recreate the mindset he had developed during his previous work in manufacturing, where all components on the wafers had to meet strict quality standards.
“The ultimate objective is not what we currently have but what we aspire to achieve,” said Mr. Delaney. He planned to implement this vision at CECAS, and the college has made remarkable progress. CECAS has overcome many of the challenges and obstacles it had in the past. As a result, Clemson’s yield rate has significantly improved, with proper measurement being a crucial factor in facilitating this progress.
Would You Recommend Applied Image Products and Services To Others?
“I decided to purchase from Applied Image online as they have been a trusted supplier of mine for over 30 years. I have bought numerous products from them, including stage micrometers, and have always been pleased with the quality of their materials. In addition, their customer support is top-notch. When I needed to return a product, the process was hassle-free, and I received a replacement quickly. Applied Image is well-known for its excellent reputation, and its parts are readily available, eliminating the need for fabrication. I highly recommend doing business with them.”
– Mr. William Delaney, Research Associate Clemson University.
Applied Image’s unique manufacturing processes and industry expertise allow us to create custom components and standards that meet the specific needs of our customers.