Heidelberg MLA150 Maskless Aligner

Sample Requirement

Size and thickness variation

• Maximum expose area: 150mm x 150mm

• Wafer: up to 8inch wafer (200mm in diameter), t=725um (+/-20um)

• Mask: up to 9inch mask (228.6mm), t=3.05mm 

• Piece: bigger than 10mm x 10mm in any side ( quadrant with 10mm radius not acceptable), no cleaving, must be diced, 

• No sample mounted on the bigger carrier substrate is acceptable (mounted on pocket wafer, mounted with photoresist, crystal bond, or Santovac oil)

• Bowed sample or sample with large thickness variation is not acceptable (PCB board, glass slide from supply room or hood area, sample with solder ball, bowed sample after thermal process). Even if you can get the good vacuum pressure, it does not mean that it will be okay with write head focus.

Resist to be exposed

• AZ photoresist, Shipley photoresist, SPR resist
• LOR or resist for lift off with bilayer with the above resist
• HMDS, MCC-Primer, Surpass for adhesion promoter before the above resist
• No SU-8 or SU-8 like resist acceptable. No laminated dry film accepted
• All the resist other than the above resist, even if standard resist mixed with other chemical or partible, must be approved by staff
• All the resist must be baked properly to dry the resist top surface
• Heidelberg MLA150 system can only photoresist, not e-beam resist such as PMMA or ZED.

Sample handling on stage

• Wear new solvent protective gloves (yellow). Do not keep using solvent gloves from previous spin-coating and soft bake.
• Only touch the adjustment aid tool, stage, and vacuum switch button. Do not touch on mirror surface on the left side. Please follow the sign "Do not touch mirror surface"
• Do not give much force or lean on the stage. Otherwise, the stage will need to be initialized.
• Please use plastic tweezer on the desk or your own plastic tweezer. Metal tweezer has scratched the stage surface, which you can see the current stage surface.

Standard Operation Protocol (SOP)

Alignment Mark Design Guideline

Top surface alignment

• Top surface alignment needs to be done in High Resolution Camera. Alignment tolerance less than 500nm can be only achieved and adjusted regularly in High Resolution Camera
• Alignment mark shape and size: cross alignment mark bigger than 190um with 5-30um thickness
• Field of View in High Resolution Camera: 190um x 140um (Low Resolution Camera: 640um x 480um, Overview Camera: 12mm x 9mm (top 30% area is dead spot))
• If you like to find the alignment easily in bigger sample such as 4 inch wafer, you had better avoid Overview Camera dead spot described above.

Bottom surface alignment

• Bottom surface alignment needs to be done in Low Resolution Camera. There is no High Resolution Camera for Back surface alignment. Overview Camera is showing top surface, not much synchronized with Low Resolution Camera in back surface alignment
• Alignment tolerance achieved and adjusted regularly: less than 1um
• Alignment mark shape and size: cross alignment mark bigger than 640um with 15-100um thickness 
• Field of View in Low Resolution Camera: 640um x 480um
• Alignment mark needs to be located on the opening of the sample stage below.

Frequently Asked Questions

Error Messages

References