Finding 10 coins in a 600-km area within 60 minutes

nspectingFrom cosmetics to semiconductors, all sorts of products must
undergo inspection prior to shipment.
Different inspection methods are required with different sorts ofproducts.
Examining and detecting in the micro-world.
This is also a job for Ushio light.

The use of light in inspecting electronic circuit lines that have been drawn with lightrequires that the object being inspected be illuminated with light of an even shorter
wavelength than that used for drawing, and then light that is reflected from the object’ssurface must be captured with high precision and the resulting image must beprocessed and analyzed using high-speed image processing technology. The precisionand speed demanded of such inspection is said to be equivalent to that of finding ten
coins scattered within a 600-km circle extending from Tokyo to Aomori with 60 minutes.
Ushio technology makes effective use of light properties such as reflection,transmission, absorption and projection to in inspection of things that cannot be seen,such as detecting scratches and defects in semiconductor circuit lines and television
LCD screens or in spectroscopy to quantitatively analyze substances in solutions.

Photo courtesy of JAXA

Solar simulator
Solar simulator completed in 1975 for theNational Space Development Agency ofJapan (NASDA, currently JAXA). For thetime, this was a large-scale system, using
an array of 19 of the world’s largest
30-kilowatt water-cooled high output
Xenon short-arc lamps in a horizontal
irradiation configuration.

Replicating the light of the sun
On the other hand, “artificial sunlight” is the light that is used for inspecting thequality of products such as solar cells and cosmetics. Such products are inspected byusing Xenon and metal halide lamps to illuminate them with light of constant intensitythat is made up of wavelengths that mimic sunlight, and then evaluating characteristics
such as UV discoloration and deterioration of strength.
Ushio’s history of virtual sunlight technology goes all the way back to the 1970s,
when it developed a large-scale solar simulator system for the National Space
Development Agency of Japan (NASDA, currently JAXA) as part of the Sunshine Project.
From nano-level semiconductors to the limitless possibilities of space development,
wherever confidence and safety depend on inspection, Ushio takes charge with light.

“Inspecting with light” The Mechanism
Semiconductor device circuit pattern inspection(inspection by image processing)Spectral comparisonof Xenon lamp andsunlightImage① Irradiation with deep UV, UV, or visible
light is used in detecting circuit shorts,opens, and thickened leads, as well as
surface contaminants and pattern
breaks.
② The surface to be inspected isilluminated and the reflected light isenlarged with lenses. Light is focused
onto an imaging element, and then theimage is enlarged to allow inspection.

■ Light fastness testing
1000W Xenon lamp
Natural light
3000K incandescent bulb

Relative strength (%)

I

During semiconductor production, the creation of 10-micron electronic circuit lines on
the surface of a 30-cm (12-inch) silicon wafer could be compared to taking the entire
Japanese archipelago, dropping it into a circle with a diameter of 3,000 km, and thendrawing an uncountable number of 1-cm lines all across that surface. Inspection is anindispensable step in determining whether those lines have been drawn correctly.

Imaging elementLens②②
Reflected light① Light

Surface profile
Wafer
Stage

Wavelength (nm)With a spectral composition close tothat of sunlight, the light produced
by Xenon lamps allows indoor UV
degradation inspection regardless ofweather.
Xenon lamp