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MJB3 Staff Page (Restricted)

iLab Name: MJB3_1 and MJB3_2
iLab Kiosk: BRK Lithography Core
FIC: David Janes
Owner: Joon Park & Mihailo Bradash

Location: Cleanroom - N Bay
Maximum Wafer Size: 3"/75 mm

Overview

General Description

The Suss MJB 3 Mask Aligner is designed for high resolution photolithography in a cleanroom environment. The MJB3 offers unsurpassed flexibility in the handling of irregularly shaped substrates and pieces of differing thicknesses, as well as standard size wafers up to 3 inches in diameter.

Specifications

• Light source: 350 W Mercury Short-arc lamp
• Exposure wavelengths: 350-450 nm, covering the g-line (436 nm), h-line (405 nm), and i-line (365 nm)

• Output intensity: 

  CP	CI1	CI2
  300W	8.0 mW/cm2 at 365 nm (i-line)	14.0 mW/cm2 at 405 nm (h-line)

• Soft contact maximum resolution: ~2 μm (optimal conditions)
• Hard contact maximum resolution: ~1 μm (optimal conditions)
• Vacuum contact (HP) maximum resolution: <0.8 μm (optimal conditions, would require purchase of vacuum chuck)
• Alignment accuracy: 0.1 μm (optimal conditions).
• X and Y travel: ±3 mm
• Theta range: ±15°
• Thickness (height) adjustment knob: 150 μm/revolution [Note: Counter-clockwise rotation decreases separation distance (increases chuck height); Clockwise rotation increases separation distance (decreases chuck height)].
  
  

Sample Requirements and Preparation

Samples should be cleaned and prepared with further processing steps in mind, as well as conditions that enable good adhesion between the substrate and photoresist.

For the aligner itself, samples must be free of resist on the substrate backside. If any resist or residue is present, it should be removed with the following process:

1. Put on a clean, new pair of solvent gloves.
2. In a solvent hood (with appropriate PPE), squirt some acetone on either a cleanroom wipe, a cleanroom swab, or a polyester wipe.
3. Hold the sample firmly with tweezers, or if necessary, with clean, double gloved hands. Note that holding with hands is only recommended if the gloved hand has touched NOTHING since being put on.
4. Carefully wipe the wafer backside with the wipe/swab, making sure not to touch the substrate front side. Acetone can wick into resist, and so should only areas of resist to be removed.
5. Repeat as necessary to remove any residue.

Proper Alignment of Wafer Pieces

The MJB3 uses a self leveling stage to automatically planarize the substrate chuck against the photomask when contact mode is engaged. This works well for wafers, but this mechanism must be considered when using small substrate pieces. When exposing on a single piece, be sure to place it directly in the center of the chuck. To further assist in proper planarization, place 3 spare substrate pieces evenly separated towards the edges of the chuck.

Standard Operating Procedure

MJB3 splitfield microscope instruction

Questions & Troubleshooting

Why is the "Nitrogen Loss" light flashing when I turn on the machine?
The "Nitrogen Loss" light may flash when the machine is turned off in iLabs before the machine has been powered off. To fix, power off the machine, disable in iLab, re-enable in iLab, and then power the machine back on. After doing this, email core staff so your previous reservation can be removed to prevent a double charge.

Why am I having so much trouble aligning for a two step lithography?
Alignment issues are typically due either to sample placement or the WEC head being out of alignment.

1) When using small samples, be sure to place them in the center of the chuck if at all possible. If this is not possible, placing 3 "helper" pieces may level the sample. See Proper Alignment of Wafer Pieces for more info.

2 )The WEC (Wedge Error Correction) head of the MJB may have drifted out of alignment. This would cause a drift in location when trying to raise the sample into contact, and would likely only be noticeable for multistep lithography alignments. Please let BNC staff know if you suspect the WEC head is not level and it will be checked.

Why isn't the height adjustment working? Why won't the contact level raise my sample into contact even though everything else is set properly?
The height adjustment knob (Z control) has likely been run beyond the lower limit or upper limit. Just report it to the staff and leave as it is.

Why is the X or Y micrometer fine adjustment unable to rotate at all?

The fine knob has been moved far beyond the travel range. Contact core staff to fix.

How do I start the lamp power supply?
BNC standard procedure is to leave the lamp power supply "on" at all times. In the rare event that a previous user has turned off the lamp power supply, follow the instructions below to restart it:

1. Flip the lamp power supply power switch on ("I" will be level with the panel, "O" will be raised)
2. Wait for the power on self test to complete (<5 minutes) and "rdy" to be displayed.
3. Be sure the MJB3 power button is off (i.e. it is not pressed. If pressed, you will not be able to start the lamp).
4. On the lamp power supply, press the "START" button. This will start the mercury vapor lamp through an ignition arc automatically repeated up to 9 times.
5. Once the lamp is ignited, "cold" will be displayed for ~5 minutes while the lamp warms up.
6. Once warm up is complete, the "CI 2" LED should be red. If either the "CP" or "CI 1" LEDs is red instead, press the "CI 2" button to switch modes.
7. Please send an email to core staff letting us know the supply was off. We will contact the previous user to let them know to leave the supply on after they are finished.

The power supply shows "rdy", what do I do?
Starting from Step 3 in How do I start the power supply? follow the remainder of the steps. There is no need to power cycle the power supply.

Process Library

References

MJB3 Manual (Internal Resource)