CORAL Name: | ev1 |
Model Number: | Electronic Visions Model EV620 Mask Aligner |
Location: | TRL |
What it does: | mask aligner |
Introduction: | The EV620 aligner is a precision mask alignment and expose system, incorporating conventional as well as back-to-front alignment capabilities. The optical system employs a splitfield revolving microscope with 5x, 10x, and 20x top-side objectives, and 10x bottom-side objectives, with joystick position and focus control. The exposure system uses a 350-watt high pressure mercury lamp and has an exposure controller with 3 channels (constant power, or constant intensity(CI) 1 or 2); the wavelengths are 365-405 nm. We always use CI 1, set at 10mW/cm2/sec. Mask sizes, including 7" masks for 6" wafers, 5" masks for 4" wafers, and a small pieces chuck are provided, and the chucks are available in both MTL's "Au" and "CMOS" contamination control standards. Multiple mask-wafer contact modes are supported, and alignment
accuracy on smooth wafers with a good mask design should
be about 1u on the frontside, and 2u's on the backside. For
backside alignment, we recommend you confirm alignment accuracy
with a tool like the TBM-8. |
Safety: | The system employs a high-pressure mercury lamp. This lamp is to be changed only by an MTL staff member. If a catastrophic failure of the lamp should occur, avoid touching glass debris or inhaling mercury vapor fumes. Notify a staff member at once. The UV light produced by the lamp can cause erythema of the skin (similar to sunburn), conjunctivitis and possible retinal burn that could result in blindness. Though the operator is protected from direct exposure to UV light it is recommended that the operator does not look at the mask/wafer assembly at the time of the exposure; indirect UV light may also harm the eye retina. Broken wafers also represent a potential eye hazard. Wear safety goggles/glasses when Using the aligner and when removing wafer pieces from the equipment.
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Procedure: |
At this point you can set the process parameters in the
recipe window.
After you have set the process parameters click on "Run", and follow screen prompts. Alternate masks and chucks are kept in slotted holders by the machine. Leave the tooling used in place at the end of a run. Note the joystick has multiple functions, including focus, by rotating the knob, and of x and y mask alignment for both the left and right optic, by choosing L or R. The joystick has a two-stage sensor, for slow movement, angle 2-5 degrees, and fast at 5-10 degrees; if you "tap" the joystick, you will go immediately to the fast setting and get large, irregular movements. Note: the joystick in the frontside y-direction moves both left and right optics together, so you will need to correct for "theta" with the micrometer. Wafer stage movement, for alignment of the wafer to the mask, is controlled by mechanical micrometers, in x, y and theta, and is done after the mask has been loaded, and aligned. When you have finished exposing your wafers click "Undo" to
unload your mask. After you unload your mask, click "Exit" to
return to the main window. "Park" the tray when you are done
Using the machine to protect it from being bumped. Leave
the machine "on" and do not exit the program.
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Author: | Kurt Broderick; John Mathias , 2/01 <kurt@mtl.mit.edu> |