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In a mask aligner, there is a one-to-one correspondence between the mask pattern and the wafer pattern. The mask covers the entire surface of the wafer which is exposed in its entirety in one shot. This was the standard for the 1:1 mask aligners that were succeeded by steppers and scanners with reduction optics. [4] There are several distinct ...
The first mask aligner, which enabled double-sided exposure, was invented in 1974. Suss MicroTec, whose name already stood for photolithography in the research and development sector, now also focused on customers from the manufacturing industry. In 1975, the first mask aligner for mass production was developed, the MJB55. [3]
This improved the life of the mask and allowed a more complex design, but had the downside that diffraction effects limited its use to relatively large features compared to the contact aligners. More annoying was the fact that the mask had to be aligned in three axes to make it perfectly flat relative to the wafer, which was a very slow process ...
Mask aligner may refer to: Clear aligners, transparent dental braces. Aligner (semiconductor), a system used to project photomasks in photolithography.
As each exposure takes as long as the entire mask in an aligner, steppers are inherently slower to use than aligners, so aligners remain in use for roles where higher resolutions are not required. Steppers increased the possible resolution many times over that of the aligners and were the first systems to allow features smaller than 1 micron.
In microlithography, typically UV radiation casts an image of a time constant mask onto a photosensitive emulsion (or photoresist). [2] Traditionally, mask aligners, steppers, scanners, and other kinds of non-optical techniques are used for high speed microfabrication of microstructures, but in case of MPL, some of these become redundant.
A proximity aligner puts a small gap of around 5 microns between the photomask and wafer. [38] In both cases, the mask covers the entire wafer, and simultaneously patterns every die. Contact printing/lithography is liable to damage both the mask and the wafer, [38] and this was the primary reason it was abandoned for high volume production ...
In the case of a photomask, there is a one-to-one correspondence between the mask pattern and the wafer pattern. The mask covered the entire surface of the wafer which was exposed in its entirety in one shot. This was the standard for the 1:1 mask aligners that were succeeded by steppers and scanners with reduction optics. [7]