Nondestructive inspection of patterns formed on inner surfaces of small diameter pipes
Inspection of patterns formed on inner surfaces of copper pipes with a small diameter of 2 mm was investigated. At first, space patterns with widths of 20-30 μm were lithographically formed using a handmade laser-scan exposure system. The exposure system was equipped with a monitoring system of a laser beam spot irradiated on the inner surface of pipe for the exposure. Pattern inspection was executed utilizing this monitoring system. In the case of exposure for patterning, the beam monitor was used for confirming the position and size of the laser beam. However, being prevented by the bright beam spot, background views were not clearly observed. For this reason, the pinhole that is initially inserted for reshaping the laser beam and making an appropriately small spot was removed, and the brightness of the beam spot was mitigated. In addition, inspected camera images were stored as video images in a personal computer using a video capture. As samples for the inspection, space patterns in resist films and groove patterns etched in copper pipes were used. As a result, resist space patterns were observed quite clearly, and pattern widths were measurable. In addition, the measured pattern widths almost agreed with the ones measured using a scanning electron microscope after cutting a half of the pipe off. On the other hand, etched groove patterns were not so clear as resist patterns. However, it was clarified that fatal pattern defects such as kinks, shifts, and breaks were detected, if the pattern images stored in the computer were carefully investigated. The new nondestructive inspection method is effective.
New Laser-Scan Exposure System for Delineating Precise Helical Patterns onto Sub-50-µm Wires
A new laser-scan exposure system for patterning onto fine wires and pipes with diameters as small as 40 µm was developed. New schemes for vertically holding specimens were adopted, and improved optics of imaging and in situ observation were used. In addition, specially contrived half-vacuum support guides were attached, and a short-wavelength violet laser with a wavelength of 408 nm was also attached. Because the laser beam spot was kept steady at a constant size by the improved half-vacuum support guide with triple narrow slits, patterns with homogeneous widths of approximately 20 µm were constantly delineated suppressing the width fluctuations to less than ±2 µm. In addition, owing to the short-wavelength laser, exposure time was greatly decreased to approximately 1/10 compared with the previous system. The new exposure system will be applicable to development of fine microcomponents such as microcoils useful for very fine probe pins of semiconductor device testers.
Real-time control of track etching and recent experiments relevant to micro and nano fabrication
Abstract Part (1) of the report sketches a computer controlled electrolytic cell system for track etching and electro replication. Track and bulk etch rates are determined in real-time. Processing can be stopped at a prescribed parameter, e.g. current, diameter, or charge. The system can be used to rapidly screen prospective track sensitive materials, selective etchants, and electro replication processes, and can thus reduce the number of necessary SEM observations. Part (2) of the report describes recent experiments relevant to micro and nano fabrication.