This tool is a one-to-one projection aligner for 6" wafers. A high intensity Mercury lamp is used to expose the 6" wafer, loaded onto a metal chuck, through a 7" mask plate and a series of mirrors.The wafer scans horizontally through an arc of light at a specified scan speed to expose the light-sensitive positive photoresist that was coated onto the wafer.
The wafers are loaded one by one onto the chuck by a pre-aligner and a load arm, then manually aligned to the mask using alignment aids designed on the mask. Auto alignment or semi-auto align is also possible using a He-Ne gas laser which reads the peaks and valleys on the mask and wafer.
A mask set made of quartz glass with the desired pattern must be designed and ordered in order to use this tool, or use a pre-existing mask set.
Specifications:
Wafer size: 5 or 6 inches
Mask size: 6 or 7 inches square
Projection System: Projection mirror, Magnification 1X, Wavelength used Exposure UV; 365 nm (i-line), 405 nm (h-line), and 436 nm (g-line)
Illuminator: 2kW super high pressure mercury lamp, Ushio USH-2002
Resolution: 2.5 um over entire 6 inch surface
Depth of Focus: more than +/- 6 um at linewidth 1.5 um
Alignment accuracy: 3 sigma, < or = 0.6 um
Pre-alignment accuracy: Within 100 um
Distance between the objective lenses: 30-109.6 mm travel right and left simultaneously from the center.
- Photolithography
