Manufacturing Bits: April 26

Multi-beam inspection; photonic pressure sensors; inside LCDs.

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Multi-beam inspection
For some time, Singaporean startup Maglen has been developing a multi-beam e-beam inspection tool technology.

Now, Maglen has reached two milestones. First, it has devised a full column test stand. The test stand includes a mechanical column and software.

The second milestone is also significant. “We also dropped our beam and obtained our very first images,” said Tony Luo, founder of Maglen.

The multi-column technology has a 1nA beam current and a 1kV landing energy. “The current structure contains 4 lenses, 1 column and 1 source. However, we tested 2 different lenses with the same column and source,” Luo said.

With the technology, the company is able to obtain images at 2nm pixel sizes. “We proved that there are no interactions in the lens array,” he said.

Maglen is able to image a silicon structure with a 200nm gap size and 1um pitch size. It has also imaged tin on carbon with 20nm diameter tin particles. The company will continue to develop its technology. “We are looking for funding to commercialize the idea,” he added.

Photonic pressure sensors
In 2014, the National Institute of Standards and Technology (NIST) developed what the agency claimed is the world’s first photonic pressure sensor.

The sensor, dubbed the fixed-length optical cavity (FLOC), could one day replace traditional mercury pressure sensors. Traditional sensors, sometimes called manometers, are used to calibrate today’s commercial equipment. It is based on a technique invented almost 400 years ago.

Now, after testing the FLOC for some time, the photonic sensor outperforms the mercury system at low pressure ranges, according to new research from NIST.

The FLOC could potentially solve several problems. A mercury manometer is about 10 feet tall and extends through the ceiling of a laboratory. It uses a toxin called mercury.

NIST researcher with the two FLOCs (copper boxes, center) and the mercury manometer (blue column, right). (Source: NIST)

NIST researcher with the two FLOCs (copper boxes, center) and the mercury manometer (blue column, right).
(Source: NIST)

The FLOC is mercury-free. Measuring 15.5cm long and 5cm square, the system consists of a temperature-controlled optical cavity, which consists of two channels. One channel is flooded with nitrogen gas and the other is a vacuum. A beam of low-power red laser light is locked to each channel. Some of the light from each channel is allowed to exit the FLOC, where the beams combine to form an interference pattern.

“This is the biggest fundamental change to pressure measurement since the invention of the mercury manometer in 1643,” said Jay Hendricks, the thermodynamic metrology group leader within NIST’s Physical Measurement Laboratory (PML). “This breakthrough will enable development of smaller and smaller standards and possibly chip-scale primary pressure standards in the future. Additionally, this technique can cover up to nine decades of pressure, a task that currently requires six different primary standards.”

Inside LCDs
The U.S. Department of Energy’s Lawrence Berkeley National Laboratory may have unraveled the mystery of liquid-crystal displays (LCDs).

Using an X-ray metrology, Berkeley Lab recorded the measurements of the tightly wound spiral molecular arrangement in LCDs. This, in turn, could give researchers insights into twist-bend molecular arrangement in LCDs.

Researchers examined the spiral “twist-bend” structure (right) formed by boomerang-shaped liquid crystal molecules (left and center) (Credit: Zosia Rostomian/Berkeley Lab)

Researchers examined the spiral “twist-bend” structure (right) formed by boomerang-shaped liquid crystal molecules (left and center) (Credit: Zosia Rostomian/Berkeley Lab)

For this experiment, researchers used the Advanced Light Source (ALS), a third-generation synchrotron at the lab. More specifically, researchers used soft X-ray scattering to examine carbon atoms in the liquid crystal molecules.

The measurements show that the crystals complete a 360-degree twist-bend over a distance of 8 nanometers at room temperature. “This newly discovered ‘twist-bend’ phase of liquid crystals is one of the hottest topics in liquid crystal research,” said Chenhui Zhu, a research scientist at Berkeley Lab.

“Now, we have provided the first definitive evidence for the twist-bend structure,” Zhu said. “The determination of this structure will without question advance our understanding of its properties, such as its response to temperature and to stress, which may help improve how we operate the current generation of LCDs.”