SUSS MicroTec MJB4 mask aligner

Where the MJB4 fits

The SUSS MJB4 is the small sibling of the MA6: a manual, tabletop mask aligner built for pieces and wafers up to 100 mm. It replaced the long-running MJB3, and many labs that buy a used MJB4 do so because their research runs on diced pieces, small compound-semiconductor wafers or 2D-material flakes on chips, not on full wafers.

Physics and materials groups like it because it is quick to learn, takes little space and works well for contact lithography on fragments. Teaching labs use it as a second aligner beside a larger tool. Its limits are clear: no bottom-side alignment in standard form, nothing above 100 mm, and a manual stage that relies on the operator.

Typical wear points on a used MJB4

Because the MJB4 is often used by many students with little formal training, the wear we see is mostly from handling rather than hours:

• Micrometer stage: stiff or slipping X, Y and theta drives, and play in the separation mechanism.
• Chuck and mask holder vacuum: cracked tubing, worn O-rings and scratched chuck surfaces that stop small pieces from sealing.
• Exposure optics: dust and haze on the condenser and mirror, reducing uniformity.
• Lamp house: lamp hours, ignition reliability and the condition of the lamp power supply.
• Microscope: dirty or misaligned objectives and a worn illumination bulb.

We measure intensity and uniformity, check contact on a test mask and record which chucks and holders are included.

Refurbishment and service

Refurbishing an MJB4 is a focused job. We replace vacuum tubing and seals, clean and realign the exposure optics, adjust the stage for smooth travel, calibrate the intensity readout and fit a new lamp if needed. For tools already in your cleanroom, a preventive maintenance visit covers the same points on a regular schedule, so the aligner does not drift out of focus between semesters.

Upgrades

The most useful upgrade is replacing the mercury lamp with a UV-LED source through our UV-LED conversion. On a small aligner that is used for short sessions, removing the lamp warm-up makes a real difference to how many users can book the tool in a day. Other options are extra chucks for small fragments and a camera alignment view so an instructor can follow what a student sees.

Facilities

• Single-phase mains power for the aligner and lamp supply
• Vacuum for the chuck and mask holder
• Nitrogen or clean dry air, depending on configuration
• Local exhaust for the lamp house with a mercury lamp fitted
• Bench or table with low vibration, under yellow light

Buying advice

Check that the mask holder matches the masks you already have; a 5 in holder will not take 7 in plates. Confirm which optics set is fitted, because deep-UV exposure needs different optics and a lamp to match. On a visit, ask for a test exposure on a small piece: a piece that will not hold vacuum, or a pattern that blurs along one edge, points to the chuck, seals or contact setting. If most of your work is on full 100 mm wafers with double-sided alignment, compare it with the MA6. The lithography category lists the other aligners and coaters we supply.