Silicon Lithography Bay

Mask Aligner - K. Suss
Location: 1.720
*****
*****Description: Mask Aligner

****Features: Contact 1:1 lithography
xxxxxxxxxxxxxExposure light wavelenght 360 nm with an intensity of 7.5 mW/cm”
xxxxxxxxxxxxxMask holder sizes available, 4"x4‰, 5"x5‰, 7‰x7‰.
xxxxxxxxxxxxxWafer size is 6‰, 4", 3" and pieces.
xxxxxxxxxxxxxMaximum wafer thickness 4.3mm
xxxxxxxxxxxxxBest resolution = 1um.
xxxxxxxxxxxxxPositive Resists: AZ 5209E and others upon request

*****Compatible Materials: Si / SiGe

*****Incompatible Materials: III-V*****
1. Log on to the tool using the LabAccess terminal.
2. Turn the vacuum pump on.
3. Check to see if the filter is in (3rd slot from the right). If you are using a quartz mask, you need the filter in. If you are using a glass mask, you need the filter out. Remove or place the filter as necessary. When not in use, the filter is placed on a wipe inside a plastic container located on the table near the aligner.
4. Now, set the UV lamp setting to either the filter ‘in’ setting CI1 (7.5 mW/cm2), or the filter ‘out’ setting CI2 (10 mW/cm2) accordingly.
5. If you need a different size wafer chuck holder than is in the machine, disconnect the three air hoses attached to the front bottom right of the stage (labeled 4, 7, 9), and then loosen the small silver screw located on the left side of the wafer chuck holder and slide the small black metal piece towards you. Then remove the wafer chuck holder with the hoses attached. Put the ‘new’ wafer chuck into the aligner, attach the metal piece and tighten the small silver screw, and connect the three air hoses (4, 7, 9) accordingly.
6. Turn the mask aligner on.
7. The aligner will prompt you to press the ‘load’ button. Make sure that the air hoses are securely fastened (they can get caught when the stage moves), and press ‘load.’ This will cause the stage to move back towards the exposure area.
8. When the stage has stopped moving, the aligner will post the current exposure time. To alter the exposure time press ‘set exposure time’ and use the ‘_’ or ‘_’ arrows to set the correct time. When the correct time has been entered, press ‘set exposure time’ again to enter in the new setting.
9. Now, press ‘align’ – this will cause the stage to move towards the optics.
10. To load your mask:
"a. Loosen the two silver knobs on the left side of the mask holder – these knobs secure the mask holder into the slot.
b. Gently slide the mask holder out towards yourself and place it upside down.
c. If you need a different size mask holder, undo the vacuum line connected to the mask holder.
d. Get the correct size mask holder, and attach its vacuum line back to the mask holder.
e. Place your mask onto the holder using the pins to line you mask up.
f. Now, turn the vacuum to the mask on, and make sure that it is holding your mask securely.
g. Next, engage the metal clip that also holds the mask to the mask holder.
h. When you are satisfied that your mask is held securely, grab the mask holder and use your fingers to hold two corners of your mask, turn the holder over, and slide it back into the slot in the stage.
i. Tighten the two silver knobs on the left side of the mask holder to secure the holder’s position."
11. Turn on the TV monitor and the optics lights (small cream-colored box labeled Karl Suss on top of the UV light source).
12. To align and expose the wafer:
"a. Slide the wafer chuck all the way out (vacuum on the wafer chuck turns off when the chuck is all the way out), and place your wafer on it lining it up with the 3 pins on the chuck. Slide the chuck back under the mask.
b. To put your wafer in contact with the mask, move the metal lever (located on the left side of the stage) to the up position. You should see the WEC light turn on.
c. Now, pull the separation lever (located on the left side of the stage) towards you to separate the mask and wafer. This is VERY important – if you try to align your wafer before separating it from the mask, you could damage the mask as well as your sample!
d. To align the wafer to the mask, you will need to use 3 knobs located on the sides of the stage. The knob-in-knob on the right side of the stage controls the ‘X’ coordinates, the knob-in-knob on the left side controls the ‘Y’ coordinates, and the large silver knob on the right side controls the wafer rotation."
"e. To control/move your view, use the arrow keys (_ _ _ _) located on the aligner panel. The ‘fast’ key on the panel toggles to move faster/slower. Use the small toggle switch located on the small cream-colored panel with black knobs (located near the right side of the aligner) to control your view to the right optic, left optic, or split field (both optics).
f. To move one optic in relation to the other in the Y direction, use the smaller knob located above the optics. The metal knob above and to the right of the right optic can move it your right view in the ‘X’ direction independently of the left optic. Similarly, the metal knob above and to the left of the left optic can move your left view in the ‘X’ direction independently of the right optic.
g. To control the focus, the large silver knob above the optics can be turned. Additionally, the small cream-colored panel with black knobs (located near the right side of the aligner), can control the focus of each optic independently using the ‘Mask Focus’ or ‘Wafer Focus’ right/left knobs.
"h. When your wafer is aligned, push the separation lever away from you to the ‘0’ position so that the mask and wafer will be in contact. Press the ‘exposure’ button – this causes the stage to move away from you and expose the wafer.
i. After exposure, the stage will then move back out – WAIT – until the wafer chuck lowers to separate the wafer and mask. You will need to push the silver lever on the bottom left side of the stage down to completely lower the wafer chuck or an error will appear (Error reads ‘Cannot move chuck down. Adj. Regulator R5.1).
j. Wait until the WEC (wafer in contact) light turns off, and pull the wafer chuck all the way out and remove your wafer.
k. ** If at any time, you decide you need to pull your wafer out before exposure (to readjust its position, etc…), slide the separation lever back to 0 to put your wafer in contact with the mask. Then push the ‘chuck down’ button on the aligner, which will pull your wafer out of contact from the mask.
13. When you are finished using the aligner:
"a. Unload your mask.
i. Loosen the two silver knobs on the top left side of the stage.
ii. Gently slide the mask holder out, holding onto the corners of the mask from underneath.
iii. Flip the mask holder over so that you can remove the mask.
iv. Turn the mask vacuum off and push the silver clip back to free the mask from the holder.
v. Put your mask away.
vi. Slide the mask holder back into the aligner and tighten the silver knobs to secure it in place.
b. Turn the optics lights off (NOT the UV lamp power – the UV lamp power always stays on).
c. Turn off the vacuum pump.
d. Turn off the aligner."
14. Log off of the tool using the LabAccess terminal.