Mechanical engineering students aim to make wafer inspections more efficient

The device uses two cameras to capture the edge of the wafer. Credit: University of Colorado at Boulder

Shortages of semiconductors – the computer chips that power products like smartphones, laptops, cars and even washing machines – continue to impact industries around the world.

Current supply chain issues are driving engineers to make inspections of the silicon wafers from which semiconductors are made more efficient. It’s a goal the industry would focus on even without the global shortage. To achieve this, mechanical engineering students at the University of Colorado have developed a device that improves the inspection process.

Mechanical engineering department seniors built a silicon wafer center search enhancement device for KLA, a semiconductor manufacturing company. The senior design team’s prototype uses two cameras to capture the edge of the circular wafer, along with computer software to calculate the radius and find the center of the wafer.

“The reason it’s important is that the KLA has to inspect those wafers for defects, and when they find one they have to know where it is on the wafer with a high level of precision,” said Marty LaRocque, the team’s electrical technician. mechanical engineer. “They have to establish a coordinate system on the wafer and the hardest part is finding the center.”

Currently, KLA detects the center of the wafer with ten different images around the edge. The student team designed their device to find the center just as efficiently with just two images.

“On one of KLA’s inspection tools, it currently takes them eight seconds to align a wafer, and we’re trying to reduce that time to two seconds,” said project manager Jack Carver. “A 75% reduction is going to get much higher throughput. With the global shortage of silicon wafer supply, any improvement in this area would be of great benefit to them.”

The real impact the students’ device could have on the industry is part of why this project appealed to them.

“It’s interesting because KLA explained to us the real meaning of our prototype,” said Prem Griddalur, the team’s system engineer. “About every two years, the size of the semiconductor gets smaller, and at the same time the scale at which they manufacture them gets bigger due to the increase in demand. KLA has done a great job in explaining why his equipment is important and how our project plays a part in the larger scheme of the industry.”

The team captured its first position from the center of the pad in early March. They are now performing statistical tests and taking measurements to verify the accuracy of the device. They need the coordinates to be within 10 microns of the true center, which is the width of a human red blood cell.

Since the team’s device is a prototype, KLA’s system may not look exactly like the students’ design. However, their prototype and testing will still provide the company with critical information to guide decisions about future designs.

The students said that this aspect is related to real-world scenarios. Typically, engineers are tasked with improving current systems, rather than creating new designs from scratch.

“That’s what our prototype is about: improving the KLA system,” said CAD engineer Hank Kussin-Bordo. “We were given the requirement that our design must work with the company’s current system because they can’t change their whole process. The challenge of being an engineer is finding ways to improve systems, while being cost-effective and not too much – complicate things.”

Designing, assembling and testing the device also allowed students to work at the intersection of engineering and electronics, a collaboration the team says is the future of the modern engineering.

“When the images from our two cameras show the tiny little patterns printed on the wafer that you can’t see with the naked eye, we all get a feeling of wow, this is real engineering here,” said Carving. .

The senior design team will showcase their silicon wafer center research enhancement device at the 2022 College of Engineering and Applied Science Engineering Projects Expo on April 22.

Engineers present the oreometer

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Provided by the University of Colorado at Boulder

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