Canon PLA-501 Contact Aligners for 4-inch Wafers

Contact: Quinn Leonard (qleonard@wisc.edu, 608-890-3030)
Instrument Center:  NFC
Instrument Location: Engineering Centers Building 3rd Floor Cleanroom

Process Description:

Lithography is a process for optically projecting an image onto a wafer that has been coated with a thin layer of photosensitive material called photoresist. Contact or proximity printing is the simplest lithography method. When UV light passes through the patterned area of a chrome mask, it exposes the photoresist on the wafer and a chemical reaction occurs. After a developing solution bath and rinse, a pattern is transferred via the remaining photoresist on the wafer.  The next process step, such as etching or ion implanting, can then be performed.

Equipment Description:

The 3” Canon aligner automatically feeds 3-inch wafers into the wafer chuck.  A pre-alignment is performed by the system.  It uses a standard 4” mask.

The light source is a 250-watt high-pressure mercury lamp that is filtered to produce a combination of g-line, h-line and i-line wavelengths. A joystick movement is used while observing the wafer and mask with a microscope to perform alignment.  The microscope is scannable ± 10mm in both the x and y directions.

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