We describe and compare the cutting and patterning of various “difficult” materials using pulsed UV Excimer, picosecond and femtosecond laser sources. Beam delivery using both fast galvanometer scanners and scanning mask imaging are described. Each laser source has its own particular strengths and weaknesses, and the optimum choice for an application is also decided by financial constraints. With some materials notable improvements in process quality have been observed using femtosecond lasers compared to picosecond lasers, which makes for an interesting choice now that cost effective reliable femtosecond systems are increasingly available. By contrast Pulsed UV Excimer lasers offer different imaging characteristics similar to mask based Lithographic systems and are particularly suited to the processing of polymers. We discuss optimized beam delivery techniques for these lasers.
In this paper, a technology and a machine tool is presented, which can be implemented in the production of Liquid Crystal Displays (LCDs), leading to a higher flexibility and reduced manufacturing costs. The developed technology focuses on the generation of transfer points by selective removal of polyimide on an Indium Tin Oxide layer with UV-laser radiation, thus replacing the conventional stamping method with cliches. With the combination of xy-stages and galvanometer scanner beam deflection, panels with dimensions of up to 400 by 500 mm<SUP>2</SUP> can be processed. On test panels, the required 2000 transfer points, distribute on the entire panel, can be processed in step and scan mode in about 30 s with an accuracy of better than 20 micrometers . The yield of the new technology in terms of working displays is comparable to the current technology. Besides LCD production, the developed machine tool has a high potential in the field of micro and precision engineering on large scale panels. The machine is highly versatile and can be used to perform a wide variety of processes in organic and inorganic materials for volume production as well as for research.
This paper presents recent results on the experimental testing of characterization methods for laser beam power and energy density distribution as described in draft ISO standards ISO 11146 and 13694. The tests were carried out using various laboratory and industrial laser sources. The accurate and repeatable measurement of distributions is of particular concern. Attention has been paid to background compensation and noise reduction methods. Tests were made to calculate beam uniformity, goodness of fit, beam size and the higher order moments of beam profile data derived from various CCD array detectors. These methods are evaluated in the context of their usefulness for on line monitoring, final laser test, and laser R&D.
The experimental testing of baseline clipping algorithms was carried out on a purposely constructed test bench. Three different lasers were used for the tests including HeNe and collimated laserdiode. The beam profile intensity distribution was measured using a CCD camera at various distances from a reference lens. Results were analyzed on an 486 PC running custom developed software written in Turbo Pascal. This allows very fast evaluation of the algorithms to be performed at rates of several times per second depending upon computational load. Tables of beam width data were created and then analyzed using Mathematica to see if the data confirmed ABCD propagation laws. Values for the beam waist location, size, and propagation constant were calculated.
Efficient line-narrowing at 308, 248 and 193 nm is reported using intracavity etalons in commercial excimer lasers. With a single etalon the linewidth is reduced by a factor of X10 - 20 at each wavelength. The line-narrowing efficiency can then be as high as 60 - 75% of the broadband output and single pulse energies in the range of 200 - 300 mJ can be produced within a linewidth of approximately 20 pm. With two intracavity etalons the linewidth is restricted a further factor of approximately X10 with line-narrowing efficiencies of 15 - 25%. At all wavelengths single pulse energies of 60 - 100 mJ could readily be produced within 2 - 3 pm. Using an laser spectrometer with a 1-D diode array readout and PC interface, the wavelength of such a line-narrowed KrF laser has been actively locked to the stable line output from a HeNe laser.