Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 03 processing: Difference between revisions
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[[Category: Equipment|Lithography]] | [[Category: Equipment|Lithography]] | ||
[[Category: Lithography]] | [[Category: Lithography]] | ||
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=Exposure technology= | =Exposure technology= | ||
Aligner: Maskless 03 is ''not'' a direct writer. In the maskless aligner, the exposure light is passed through a spatial light modulator, much like in a video projector, and projected onto the substrate, exposing a small area of the design at a time. The substrate is fully exposed by scanning the exposure field across the substrate in a succession of exposure stripes. | Aligner: Maskless 03 is ''not'' a direct laser writer. In the maskless aligner, the exposure light is passed through a spatial light modulator, much like in a video projector, and projected onto the substrate, exposing a small area of the design at a time. The substrate is fully exposed by scanning the exposure field across the substrate in a succession of exposure stripes. | ||
The light source is a laser diode (array) with a wavelength of 405 nm (8 W). The spatial light modulator is a digital micro-mirror device. The individual mirrors of the DMD are switched on and off in order to represent the design, and the laser is flashed on and off, in order to give the desired exposure dose. The exposure image is projected onto the substrate through a lens-system. The projected image has a pixel size of 500x500 nm on the substrate surface. The image is scanned across the substrate in stripes in order to expose the entire design. Each stripe is overlapping 2 or 5 times, depending on the chosen [[Specific_Process_Knowledge/Lithography/Aligners/Aligner:_Maskless_03_processing#Exposure_mode|exposure mode]]), in order to reduce light-source non-uniformity effects and stitching errors. The address grid size is 250 nm or 100 nm for Fast and High Quality exposure mode, respectively. | The light source is a laser diode (array) with a wavelength of 405 nm (8 W). The spatial light modulator is a digital micro-mirror device. The individual mirrors of the DMD are switched on and off in order to represent the design, and the laser is flashed on and off, in order to give the desired exposure dose. The exposure image is projected onto the substrate through a lens-system. The projected image has a pixel size of 500x500 nm on the substrate surface. The image is scanned across the substrate in stripes in order to expose the entire design. Each stripe is overlapping 2 or 5 times, depending on the chosen [[Specific_Process_Knowledge/Lithography/Aligners/Aligner:_Maskless_03_processing#Exposure_mode|exposure mode]]), in order to reduce light-source non-uniformity effects and stitching errors. The address grid size is 250 nm or 100 nm for Fast and High Quality exposure mode, respectively. | ||
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The correct way to determine the best dose-defocus settings is to generate a so-called Bossung plot (known from projection lithography), which plots the printed linewidth as a function of dose and defocus. From this, the most stable region of parameter space is chosen, i.e. the region where the linewidth changes the least when dose and defocus changes. Any deviation from the design linewidth may be corrected using the CD bias parameter. This typically involves SEM imaging of resist cross-sections, and quickly becomes time consuming. However, in most cases, inspection of a dose-defocus matrix (easily generated using the series exposure function) in an optical microscope will get you most of the way. | The correct way to determine the best dose-defocus settings is to generate a so-called Bossung plot (known from projection lithography), which plots the printed linewidth as a function of dose and defocus. From this, the most stable region of parameter space is chosen, i.e. the region where the linewidth changes the least when dose and defocus changes. Any deviation from the design linewidth may be corrected using the CD bias parameter. This typically involves SEM imaging of resist cross-sections, and quickly becomes time consuming. However, in most cases, inspection of a dose-defocus matrix (easily generated using the series exposure function) in an optical microscope will get you most of the way. | ||
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==Exposure dose and defocus== | |||
[[Specific Process Knowledge/Lithography/Resist#Aligner:_Maskless_03|Information on UV exposure dose]] | |||
==Exposure mode== | ==Exposure mode== | ||