Karl Suss MJB4 Mask Aligner Tool Manager: Yong Sun ( yongs@princeton.edu; Office 8-8234; Cell 609-917-5076 ) Backup: George Watson ( gwatson@princeton.edu; Office 8-4626; Cell 732-996-2713 ) ****************************************************************************** Introduction The MJB4 mask aligner is a compact, flexible and high-precision alignment tool. It can print features in the submicron range, with alignment accuracy around 1 m or better. MJB4 can handle substrates up to 100 mm in diameter. The combined thickness of mask/substrate can be up to 9 mm. There are 5 different printing modes currently available on the MJB4: 1). Soft Contact: Variable mechanic pressure 2). Hard Contact: Variable mechanic pressure + additional nitrogen pressure 3). Vacuum Contact: Evacuate the gap between mask/substrate + Hard Contact 4). Low Vacuum Contact: Evacuate the gap between mask/substrate + Soft Contact 5). Gap Printing: Exposure with variable gaps between mask/substrate The optical system is equipped with 400nm exposure optics, utilizes an Hg Arc lamp as its light source. The best resolution achievable by different modes is: (i). Vacuum Contact 0.8 µm; (ii). Hard Contact ~1 m; (iii). Soft contact ~2 m; (iv). Gap Printing 3 m. Our MJB4 has one top side alignment (TSA) microscope, can do singlefield alignment. It can also do back side alignment (BSA) for IR-transparent substrates, such as GaAs, InP, Si, etc. Relative UV Intensity UV400 Spectrum Optical System of Suss MJB4 Mask Aligner
Warning: (1). Keep a safe distance from the aligner prior to the microscope movement (2). UV light can lead to permanent eye damage and skin burns (3). Never open the lamp house when the lamp is still hot (it may explode!) Remember to LOG IN online @ https://prz-mnfl-l.princeton.edu/ Step 1. Check the initial condition of the mask aligner Check the lamp house, make sure you can see the UV light. Otherwise ask the staff or superusers to switch on the lamp. Do not operate CIC1200 unless you are authorized to do so. If the lamp is just switched ON from cold (initially OFF), wait 20 minutes before it stabilizes. Verify Pneumatic Settings: 1). Compressed Air (CDA): 5.5 bar 2). Nitrogen Pressure: 1.5 bar 3). Vacuum Pressure: -0.8 bar 4). WEC Pressure: 0.2 bar An error message will appear on the touch screen if the pressure settings deviate by -20%. If the error message keeps on popping up, stop using the tool and notify the staff. Move the sample stage to its Home position. Home is where Stage-X Motion is set to 10 mm, Stage-Y Motion to 10 mm, Theta to 0. The travel range for stage-x & -Y motion is ±5 mm, the range for Theta is ±5. Typical MJB4 Mask Aligner (with two TSP microscopes) 1. Lamp house 2. TSA microscope manipulator 3. Microscope focus setting 4. TSA microscope 5. TSA/IR illumination 6. Electronics ON/OFF key 7. Main switch 8. Alignment stage 9. Monitor for microscope 10. Pneumatic settings 11. Display/touch screen 12. Pneumatic gaugues
Step 2. Load the mask The adapter frame for 5 masks is different from the one for 4 masks. Depending on the size of your masks, and the adapter frame may need to be changed first. Place your mask on the mask holder, with its Cr side facing up. In the main menu, press Mask vacuum is off on the touch screen, when it changes to Mask vacuum is on, the mask is fixed by vacuum. Manually check the mask to confirm. Flip the mask holder. With the Cr side facing down, slide it into the adapter frame. Fasten the mask holder by tightening the two knurled screws on the right-hand side of the frame. Step 3. Load the substrate Turn the thickness setting knob clockwise, lower the stage to a safe distance from the fixed mask (one turn of the thickness setting knob = 150 m; standard mask thickness ~2.3 mm; standard 4 Si wafer thickness ~500 m; maximum mask/substrate thickness allowed 9 mm). Pull out the transport slide as far as possible, insert a suitable substrate chuck on the slide. Reminder: some chucks were designed for MJB3, which fit well on the transport slide, but have no vacuum through-hole the substrate is not fixed by vacuum during loading. Place your substrate on the stage chuck, with the resist side facing up. Fix the substrate with vacuum by pressing the hand valve on the front right side of the transport slide. Carefully insert the slide until it reaches the end stop. Stage coordinate system MJB4 Alignment Stage 1. Stage-Y motion 2. Separation lever 3. Alignment gap setting 4. Contact lever 5. Variable thickness setting (with locking lever) 6. Stage-Theta motion 7. Stage-X motion
Step 4. Wedge Error Compensation (WEC) Verify the separation lever is pushed to the far back end (contact position), adjust the alignment gap setting knob (max alignment gap = 50 µm, to the front end), tighten the knob until it is snug. In the main menu, press WEC setting on touch screen. When Close contact lever appears, push the contact lever to the far end. Then follow the instructions on the touch screen, turn the thickness setting knob counterclockwise, slowly move stage up until it says WEC setting OK. Lock the thickness setting knob with the locking lever (on the side of the thickness setting knob). Then pull back the contact lever. Note: During WEC, the substrate is pushed against the mask by a defined amount of force. When setting the WEC pressure, remember it should compensate the weight of the stage chuck, and should also be proportional to the substrate surface. Step 5. Select the correct parameters In the main menu, press Parameters on the touch screen, select the correct exposure parameters and load them. 1. Exposure Type: Align + Exp. With mask, may need alignment Flood Exp. No mask, no alignment Test Exp. 2. Exposure Mode: Soft Contact Less damage to mask/wafer Hard Contact Vacuum Contact Best resolution Low Vacuum Contact Gap Exposure Worst resolution 3. Illumination: IR trans. light Back side alignment (BSA) Reflected light Top side alignment (TSA) 4. Time: Exposure time Hard contact time Default 5s Pre-vacuum time Default 5s Full vacuum time Default 5s Exposure cycles Default 1 To save the settings, press Recipes in the main menu, store the settings under a specific name using the Recipe Editor. Step 6. Perform initial alignment Push the contact lever to the far end, the microscope will move down automatically. Adjust the separation lever to create an appropriate gap between the mask & substrate. Turn on the illumination (Never set the illumination to its full power, the camera will saturate and you will see nothing on the monitor). Look through the microscope, or use the camera/ monitor to adjust the focus and find your alignment marks. Perform initial top side alignment by moving the substrate with the stage motion knobs for X, Y and Theta, carefully align the marks on the mask/substrate. To do back side alignment, please contact the staff for further instructions.
Step 7. Alignment check and exposure Carefully push the separation lever back to its contact position, press Alignment check. If the alignment shifts slightly, you may pull back the separation lever, adjust the substrate slightly, then push the separation lever to its contact position, check the alignment again. Repeat the above steps until the alignment between the mask/substrate is satisfactory to you. Press Exposure, the microscope will move up, the mirror house will move to the front, and the shutter will open for the programmed UV exposure. During the exposure, check the light intensity (the intensity will show on the Constant Intensity Controller CIC1200, which is under the aligner table, default value ~31.5 mw/cm 2 for λ = 365 nm, i-line) Step 8. Unload the substrate/mask When the UV exposure is done, the tool will beep, the microscope will move up by itself. Open the contact lever, pull out the transport slide, unload your substrate, then push the transport slide back in. Loosen both knurled screws on the right-hand side of the adapter frame. Carefully slide the mask holder out, and place it on a tray upside down. Press Mask vacuum is on in the main menu, hold it for 2 seconds, until it changes to Mask vacuum is off. Then unload your mask. Remember to switch off the microscope illumination, and move the stage back to Home. Before you leave, remember to LOG OUT of MJB4 online ************************************************************************************* Instruction of CIC1200 To be operated by Authorized Users ONLY 1. To Reset the Lamp Life If the lamp is on, turn it off first, wait ~20min until the lamp is cold Actuate the key SET LAMP, press and hold it for 2 seconds Press the key + or - to choose the right LAMP TYPE (we use 350W Hg) Validate by pressing SET LAMP for another 2 seconds The display will show Stored, then L: RESET? i) To reset the lamp life, press +, the? will disappear from the display Press SET LAMP again, the display will show STORED, then STAND BY ii) To leave the stored lamp life in memory, press SET LAMP right after L:RESET? 2. To switch on the lamp Verify the lamp house is cold, press the key ON, the display will show Ready Press CP (constant power), and START, it will show IGNITION then LAMP COLD The LAMP LIFE/POWER error will flash until the lamp reach its operating conditions After CIC1200 displays LIGHT INTENSITY, press CH1 (constant light intensity)