Lamp-mask patterning

A SU8-100 photoresist solution (PRS) was used in all of the procedures. In order to make the three-layer photoresist patterns for the top master, the first layer was coated as 50 pm thick on a 100 mm diameter silicon wafer 2mL PRS was spun at 500 rpm for 10 s following at 5000 rpm for 30 s with a spin coater. The spin-coated wafer was baked at 60 °C for 10 min, and then at 95 °C for 30 min. After baking, the photomask image (Figure 4.5A) was patterned on the first layer using a UV lamp (370 nm) in a mask aligner for 30 s. On the exposed first layer without a developing step, the second layer for the profile of the ESI emitter was coated as 200 pm thick 4mF PRS was spun at 500 rpm for 20 s followed by 2000 rpm for 30 s. The wafer coated with two layers was baked at 60 °C for 20 min, and then at 95 °C for 60 min. The baked wafer was exposed with a second... 

Furthermore, we widened the scope and potential application fields using different activation methods. Low-pressure and atmospheric-pressure plasma sources as well as vacuum UV lamps were used for large area exposures and, in combination with shadow masks, to produce patterns in the micrometer to millimeter range. Exposures at LIGA beamlines were used to produce bulk structures and electron beam writers to generate arbitrary high-resolution structures. 

The mask image is transferred to the wafer using a computer-controlled machine known as a stepper. It has a sophisticated lens system to reduce the pattern on the mask (millimetres-centimetres diameter) to the microscopic dimensions of the chips circuitry. The wafer is held in place on a positioning table below the lens system. UV light from an arc lamp or a laser (or X-ray irradiation or electron beam radiation) shines through the clear spaces of the mask s intricate pattern on to the photoresist layer of a single chip. The stepper table then moves the wafer the precise distance required to position another chip under the light. 

The term hiding powef as used in this report refers to the ability of light-diffusing films to mask the light and dark pattern produced by, for example, a Unear array of fluorescent lamps (e.g., cold cathode fluorescent lamps). Quantitatively, Figure 1 and the foUowing equation can mathematically describe hiding power ... 

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