KARL SUSS MJB3 MASK ALIGNER STANDARD OPERATING PROCEDURE

Transcription

1 KARL SUSS MJB3 MASK ALIGNER STANDARD OPERATING PROCEDURE Purpose of this Instrument: This instrument is for patterning photosensitive polymers with UV light. Location: White Hall 410 Cleanroom Primary Staff Contact: Harley Hart (412) (M) (304) (O) Office: White Hall 409 Secondary Staff Contact: The Shared Research Facilities are operated for the benefit of all researchers. If you encounter any problems with this piece of equipment, please contact the staff member listed above immediately. There is never a penalty for asking questions. If the equipment is not behaving exactly the way it should, contact a staff member. WARNING: The Mask Aligner emits UV light. Exposure of UV light on unprotected skin can cause severe burns. Looking directly into the UV light source can cause temporary or permanent blindness. WARNING: If at any time during operation, there is a sound of shattering glass and the voltage led display on the lamp power supply drops to zero or displays fail turn off the lamp controller and the Mask Aligner, evacuate all users from the room, and notify a Shared Research Facilities staff member. Do not attempt to open the system or inspect the arc lamp! Mercury vapor may be released if the arc lamp breaks. Opening the lamp housing will expose you to this vapor. ATTENTION: Users are required to wear UV protective glasses when operating the Mask Aligner. These glasses are located on top of the Mask Aligner.

2 INSTRUMENT START UP 1. Reserve the equipment in CORES and login using the CORES kiosk in the cleanroom entry lab. 2. Sign into the logbook at the instrument. 3. Check the compressed air pressure gauge behind the instrument and before the nitrogen generator. Record this value in the logbook. The pressure reading should be between psi see Figure 1. If it is not within this range, contact a Shared Research Facilities staff member. Figure 1: Pressure before the nitrogen generator 4. Check the compressed air pressure gauge after the nitrogen generator behind the instrument that is attached to the optical table. Record this value in the logbook. The pressure reading should be between psi see Figure 2. If it is not within this range, contact a Shared Research Facilities staff member. 5. Turn on the vacuum pump behind the instrument by pressing the black toggle switch to the ON position and listen for the pump to start see Figure 3. This is required for vacuum to occur at the sample holder and at the mask holder. Figure 2: Pressure regulator after the nitrogen generator 1

3 Figure 3: Image of the vacuum pump 6. Make sure the Mask Aligner is powered OFF. Power up the lamp controller by turning on the power switch on the right hand side of the panel. A picture of the lamp controller is shown in Figure 4 and it is located to the right of the Mask Aligner. Once turned on, the lamp controller led panel will cycle through a warm-up procedure and then the display will read rdy for ready. NOTE: The lamp power supply is interlocked with the Mask Aligner. The lamp cannot ignite if the Mask Aligner is on. Figure 4: Lamp Controller in idle state 7. Start the arc lamp by pressing, and holding for a few seconds, the start button. If the arc lamp ignites successfully, the led display on the lamp power supply will show cold. If the lamp does not ignite immediately, it will attempt ignition five times. If the lamp controller does not display the cold message but displays fail or continues to display rdy, then try again. If the lamp does not ignite after the third attempt, please contact a Shared Research Facilities staff member for assistance. 8. Wait 15 minutes for the lamp to warm up. The led display on the lamp power supply should read 275 Watts. WARNING: If the power does not read 275 W do not proceed. Attempting to run the lamp at a higher idle power may cause the lamp to fail or crack. Contact a Shared Research Facilities staff member for assistance. 2

4 9. Power on the Mask Aligner by pressing the red POWER button on the control panel and verify the following system nitrogen pressures on the front of the instrument see Figure 5: Exposure: 4 Bar White Hall Mask Aligner Parallelity: 2 Bar Pressure/Wafer: 1 Bar Figure 5: Nitrogen Pressures on Mask Aligner 10. Turn the microscope power supply toggle switch to the ON position as shown in Figure 6. The microscope lamp will turn ON. Figure 6: Microscope Power Supply MEASURING THE LAMP INTENSITY 1. The output UV intensity should be measured and recorded in the log book when the lamp has been turned on. Make sure that the lamp has warmed up before taking the UV measurement by waiting 15 minutes. 2. Turn on the power to the Karl Suss 1000 UV intensity meter and probe, shown in Figure 7. The probe should have a label on the side marking it as a 365nm probe. Figure 7: Karl Suss 1000 UV Intensity meter with probe 3

5 3. Place the UV probe on the stage and move the stage into contact position by moving the contact lever on the left-hand side of the instrument counterclockwise to the CONTACT position. The CONTACT light will illuminate. Then press the HP/ST button and the VACUUM chamber button both buttons should illuminate - to apply vacuum to the back of the probe. This will hold the sensor in place during exposure see Figure 8. Figure 8: Probe on Stage 4. Set the exposure time to 10 seconds and press the EXPOSURE Button. The mirror housing will move forward and expose the sensor as shown in Figure 9. Figure 9: UV measurement in progress 5. Record the UV meter value and record it in the logbook. Units are in mw/cm This process should be repeated with the photo-mask placed over the 365nm UV probe for experimental calculations to determine the through mask intensity. NOTE: Make sure that the silver disc is not covered by any darkened area of the mask. If any part of the mask covers the silver disc area, then the measured value will be lower than the actual UV intensity. 7. Calculate the exposure time by dividing the desired exposure dosage, which should be in mj/cm 2 by the UV intensity measured through the mask in mw/cm 2. Exposure time (s) = Exposure Energy (mj/cm2 ) UV Intensity (mw/cm 2 ) NOTE: Make sure to record both the measured intensity and calculated time in your lab notebook. The measured intensity will change over time, resulting in a change in exposure time. 4

6 LOADING A MASK 1. Mount the photo-mask on one of the mask holders shown in Figure 10a & 10b. The photo-mask should be positioned so that the chrome side of the photo-mask is facing up and manually centered over the mask holder opening. NOTE: If the 3 sample holder is to be used, the mask holder will need to be changed by disconnecting the vacuum line from the photo mask holder for 2 samples and connecting it to the photo mask holder for 3 samples. Figure 10a: Photo-mask holder for 3 sample holders Figure 10b: Photo-mask holder for small pieces and 2 sample holders 2. Press the VACUUM MASK button on the control panel of the Mask Aligner and check that the photo-mask is securely attached to the holder by trying to gently move the mask. NOTE: The mask should be centered in the mask holder. If the mask is placed too close to the front or back edge of the holder, it will interfere with mask holder insertion and potentially damage the mask. 3. Rotate the microscope objective turret so that the 10x objective is over the stage. 5

7 4. Pick up the mask holder, and flip it over. Insert the mask holder into the mask holder grooves on the Mask Aligner see Figure 11. Figure 11: Grooves for mask holder 5. Fully insert the mask holder, and make sure that the holder is flush and level with the Mask Aligner. Tighten the mask holder knobs on the front of the instrument see Figure 12. Figure 12: Mask holder with photomask installed LOADING A WAFER 1. Insert the desired sample holder into the transport slide and verify that the sample holder is secured and that the transport slide post is properly inserted into the notch of the sample holder see Figures 13a & 13b. Figure 13a: 3 Sample Holder Figure 13b: 2 Sample Holder Figure 13c: Small pieces Sample Holder 6

8 2. Place the sample on the sample holder and verify that all vacuum holes are covered see Figure 14 below. Failure to completely cover all holes will lead to loss of sample vacuum during processing. Figure 14: Sample properly loaded onto the small piece sample holder 3. Squeeze the button on the front of the finger grip located at the right-hand side of the transport slide. This will hold the substrate in place. Then gently move the transport slide completely to the left under the mask. ALIGNING A WAFER TO THE MASK 1. The idle position of the variable thickness adjustment knob is 10. The thickness of each user s wafers is different, so this position will need to be adjusted by each user to achieve the proper alignment gap. While viewing through the microscope, gently move the contact lever, which controls the z-axis of the stage, on the left-hand side of the instrument counter-clockwise while watching for the shadow between the sample and the photo-mask to disappear and while feeling for resistance in the contact lever. The preferred variable thickness adjustment knob position is for the shadow to disappear when the contact lever has reached the black line on the side of the instrument see Figure 15 below. If your sample begins to make contact with the photo-mask before reaching the CONTACT position, then increase the value of the variable thickness adjustment knob. If your sample does not make contact with the photo-mask before reaching the CONTACT position, then decrease the value of the variable thickness adjustment knob and repeat. NOTE: Each revolution of variable thickness adjustment knob is equal to 150 microns. 7

9 Figure 15: Contact Lever WARNING: Always be aware of the microscope objectives position in relation to the photo-mask as it is possible to collide the objectives with the photo-mask and/or mask holder. This can result in damage to the objectives and/photo-mask. NOTE: To change the variable thickness adjustment knob value, first unlock the position of the adjustment knob by moving the locking tab counter-clockwise. Once the value is changed, be sure to lock the position by moving the locking tab clockwise as shown in Figure 16. Figure 16: Variable thickness adjustment knob WARNING: Only adjust the variable thickness adjustment knob whenever the CONTACT lever is in the retracted position. Failure to do so can result in damage to the instrument. Users are responsible for resetting the variable thickness adjustment knob back to 10 when their process is completed. 8

10 2. Select an exposure mode by pressing the appropriate buttons. The possible Exposure modes are as follows: Standard Mode (ST): SOFT CONTACT: The ST button and the SOFT CONTACT buttons are illuminated. This brings the substrate into contact with the mask using the only pressure applied from the contact lever. NOTE: Sample carriers without vacuum gaskets are required to use this mode of operation. HARD CONTACT: ST mode button is illuminated on the control panel and the SOFT CONTACT button is not. Prior to exposure vacuum will be removed and nitrogen pressure will press the substrate against the mask. Once exposure is complete the nitrogen pressure will be removed and vacuum will be reapplied to the substrate HP Mode: High Precision is used to achieve the highest possible resolution as this method creates the smallest gap possible between the photo-mask and the substrate. Prior to exposure the vacuum under the substrate is switched OFF and vacuum between the substrate and mask is switched ON. Then after exposure the vacuum between the substrate and mask is switched OFF and vacuum under the substrate is switched back ON. 3. Move the CONTACT LEVER counterclockwise to bring the substrate into contact position. The SEPARATION LEVER cannot be used unless the CONTACT LEVER has the sample in the contact position. 4. Move the SEPARATION LEVER to the front of the instrument. A small flow of nitrogen will be introduced into the vacuum chamber to ensure that the substrate separates from the photo-mask. The SEPARATION indicator light on the control panel will illuminate and the CONTACT light will power off - see Figure 17. Figure 17: Separation Lever in the sample separated position 9

11 NOTE: If the substrate continues to adhere to the photo-mask during SEPARATION, then the nitrogen throttle pressure can be increased. If the substrate shifts during SEPARATION, then the nitrogen throttle pressure needs to be decreased. Please contact a Shared Research Facilities staff member. 5. Focus the microscope using the focus adjustments knobs shown in Figure 18. NOTE: The microscope focusing knob has combined coarse/fine focus adjustment. If the focus knob is turned in only one direction, then coarse adjustment will occur. Fine focus adjustment is automatically selected whenever the slightest turn is made in the opposite direction. The adjustment will switch back to coarse adjustment whenever the fine focus adjustment limits are exceeded. Figure 18: Microscope adjustment knobs 6. Using the X position, Y position, and θ position micrometers shown in Figure 19a, as well as the microscope manipulator shown in Figure 19b, adjust the position of the substrate features to line up with the mask patterns. For best results, use the θ position micrometer to align the substrate rotation first, before adjusting the X and Y positions. 7. Then move the SEPARATION LEVER backwards to move the sample into the contact position. The SEPARATION indicator light will go out and the CONTACT light will illuminate. Figure 19a: X, Y, and Theta Alignment knobs Figure 19b: Microscope Manipulator 10

12 NOTE: The microscope manipulator moves on X-Y slides which are equipped with pneumatic brakes. The two buttons located on the manipulator unlocks either or both the X and Y brakes. This allows the microscope to be scanned in either the X or Y directions exclusively or in both directions simultaneously. 8. Once the substrate is in contact with the photo-mask, set the timer to the desired setpoint for exposure on the exposure time see Figure 20. Verify that the proper units have been selected. Figure 20: Exposure timer 9. Check that the sample is in desired EXPOSURE mode by checking that the proper CONTROL PANEL lights are illuminated from Step # Say EXPOSE to inform all lab users about the UV hazard. Press the EXPOSURE button on the control panel, the vacuum light will turn off and the mirror will move forward and expose the sample. Turn your eyes away from the instrument until the exposure is complete. 11. Once the exposure is complete, the mirror will retract to its original position. 12. Move the CONTACT LEVER clockwise to the retracted position. This will bring your sample away from the photo-mask. 13. Squeeze the button on the front of the finger grip located at the right-hand side of the transport slide. This will hold the substrate in place. Then gently move the transport slide completely to the right. Then using tweezers remove your sample. 14. If a second sample is to be processed, refer back to step# 1 of this section. 11

13 TURNING OFF THE SYSTEM 1. Before shutting down the system, the user must first remove the mask from the aligner. To remove the mask, loosen the two mask holder knobs and slide holder to the left. Place the holder upside down on the table to the left of the instrument. Press the VACUUM MASK button to OFF on the front of the instrument and then remove the mask and place the mask in the storage container. WARNING: Do not turn off the VACUUM MASK button unless the holder is upside on the table. Failure to do so can lead to mask damage or breakage. 2. Set the variable thickness adjustment knob is set to 10 and ensure the tab on the micrometer is in the lock position. 3. Rotate the microscope objective turret until the 10x objective is over the sample stage. 4. Center the aligner stage by setting the X micrometer to ~5 and the Y micrometer to ~10. The θ micrometer can be adjusted to center the rotational indicator. 5. Turn the microscope power supply toggle switch to the OFF position. The microscope lamp will turn off. 6. Power off the Mask Aligner by pressing the red POWER on the front control panel. 7. Power off the lamp controller by turning off the POWER switch. 8. Turn off the system vacuum pump at the back of the instrument by moving the black toggle switch to the OFF position. 9. Clean up the work area and make sure that all requested parameters have been entered into the log book. 10. Sign out of the CORES system using the barcode scanner in the entry lab. NOTE: If any issues with the instrument were observed, the user must send an to the SRF staff with PROBLEM REPORT in the subject and enter a detailed summation of the issue observed. 12

14 EMERGENCY SHUT-DOWN PROCEDURES If, at any time, the user needs to contact someone for help, call or locate the following staff of the Shared Research Facilities (SRF): Primary Staff Contact: Harley Hart (412) (M) (304) (O) Office: White Hall 409 Secondary Staff Contact: Dr. Kolin Brown (304) (304) (O) Office: ESB G75D If no one is available and the instrument is not acting as expected, the user should do the following: Turn OFF the system power Turn OFF the lamp power supply Turn OFF the vacuum pump Then, if possible, the user should stay by the instrument while trying to contact a Shared Research Facilities staff member. If it becomes necessary to leave the instrument then the user should leave a large, legible note on the MASK ALIGNER stating: The problem (describe what happened and steps taken) When it occurred (date and time) User name and phone number If it becomes necessary to leave the instrument then the user should leave a large, legible note at the MASK ALIGNER stating the instrument is DOWN. If a dangerous situation is evident (smoke, fire, sparks, etc.), or if the sound of shattering glass is heard emitting from the lamp housing, ONLY if it is safe to do so, the user should turn off system, lamp controller, and vacuum pump or unplug the instrument and leave the cleanroom immediately. The user should notify all other cleanroom persons within the cleanroom to evacuate. The user should then contact proper emergency personnel. The contact numbers can be found posted outside of the cleanroom or on the cover of the instrument log book. 13