Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 04 processing: Difference between revisions
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Control of the exposure dose differs between the two available exposure modes. In Raster mode, the dose is directly controlled by the on-time of the DMD mirrors during exposure, and the dose process parameter is thus simply given in units of mJ/cm<sup>2</sup>. As the intensity of the exposure light at the substrate surface cannot easily be measured, this dose is indirectly calibrated at the factory, by adjusting the optimal dose to match the known dose of a particular resist. | Control of the exposure dose differs between the two available exposure modes. In Raster mode, the dose is directly controlled by the on-time of the DMD mirrors during exposure, and the dose process parameter is thus simply given in units of mJ/cm<sup>2</sup>. As the intensity of the exposure light at the substrate surface cannot easily be measured, this dose is indirectly calibrated at the factory, by adjusting the optimal dose to match the known dose of a particular resist. | ||
<br>In Vector mode, however, the exposure dose is determined by combination of four different process parameters: | <br>In Vector mode, however, the exposure dose is determined by combination of four different process parameters: | ||
*Pen [1, 2, 5, 10, or 25 µm] | *Pen [1, 2, 5, 10, or 25 µm]; the size of pinhole projected onto the substrate surface | ||
*Transmission [30, or 100 %] | *Transmission [30, or 100 %]; the transparency of the filter in front of the pinhole | ||
*Laser Power [0-120 mW] | *Laser Power [0-120 mW]; the output power of the diode laser | ||
*Exposure Velocity [0-200 mm/s] | *Exposure Velocity [0-200 mm/s]; the movement speed of the stage during exposure | ||
The Pen determines the size of the spot on the substrate surface and thus the ultimate resolution. It may also affect the intensity available at the substrate. For highly sensitive resists, the Transmission can be used to | The Pen determines the size of the spot on the substrate surface and thus the ultimate resolution. It may also affect the intensity available at the substrate. For highly sensitive resists, the Transmission can be used to limit the available intensity at the substrate (lowering the required Exposure velocity in a more reasonable value). The Laser Power directly affects the intensity available at the substrate. The Exposure Velocity determines the dwell time at each point on the substrate, and thus the effective dose received by the resist at the intensity determined by the three other parameters. | ||
Aligner: Maskless 04 offers not only two exposure modes, but also two autofocus modes; optical or pneumatic. The defocus process parameter is used to compensate for offsets between the autofocus mechanism and the focal point of the exposure light, and simultaneously optimize print quality in different resists and varying thicknesses. The "defoc" parameter us a unitless value, representing ±100% of the available correction available above and below the initial focus point established during loading of the substrate. One defoc step is approximately 0.25µm. Positive defoc is into the resist, i.e. writehead moves down when defoc is increased. | Aligner: Maskless 04 offers not only two exposure modes, but also two autofocus modes; optical or pneumatic. The defocus process parameter is used to compensate for offsets between the autofocus mechanism and the focal point of the exposure light, and simultaneously optimize print quality in different resists and varying thicknesses. The "defoc" parameter us a unitless value, representing ±100% of the available correction available above and below the initial focus point established during loading of the substrate. One defoc step is approximately 0.25µm. Positive defoc is into the resist, i.e. writehead moves down when defoc is increased. | ||