Lithography Processes

Optical and e-beam lithography processes with both positive and negative-tone resists are available for substrates from 200-mm-diameter wafers down to samples below 10 mm in size and square mask plates up to 9 inches.

Direct-write lithography with a 405 nm laser writer for processing samples from 10 mm in size to wafers up to 200 mm and mask plates up to 9 inches, as well as exposure on flexible substrates.

With positive tone photoresists (AZ series):

• standard process thickness 600 nm, 1000 nm, 1200 nm, 2200 nm for wet and dry etch processes
• limited capabilities with 200 nm for highest resolution
• limited capabilities with 4 µm to 20 µm
• standard process with underlying LOR layer for lift-off process
• process with negative profile with 600 nm photoresist (for lift-off of metal deposition) 
• bilayer resist with lift-off resist
• grey-level lithography (60 levels available) for 2.5D fabricated structures

With positive tone photoresist series for greyscale lithography (ma-P 1200 series):

• film thickness up to 60 µm
• grey-level lithography (128 levels available) 

With negative tone photoresists (mr series):

• processes with 1 to 40 µm epoxy resin for direct-write for specific applications (microelectronics passivation, epoxy micromachines, microfluidics)

INL cleanroom is equipped two Mask Aligners dedicated for production. One uses a mercury lamp and 7-inch masks, using different UV bands with top and bottom alignment. The other uses 9-inch masks and an LED source; can perform automated alignments for an increased throughput and precision in aligned exposure from both top and bottom sides.

With positive tone photoresists (AZ series):

• standard process thickness 600 nm, 1000 nm, 1200 nm, 2200 nm for wet and dry etch processes
• standard process with underlying LOR layer for lift-off process

With special resists:

• UV-sensitive polyimide (e.g., for flexible devices)
• Photo sensitive ProTEK PSB (negative-working etch mask for KOH wet etch for silicon micromachining)
• UV-sensitive SU-8 (negative tone photoresist up to 150 um thickness)

Nanoimprint lithography is a recent addition to the capabilities of INL, enabling the patterning of a wide range of hard and soft materials and the fast fabrication of 3D micro- and nanostructures in a single step. The masters to be used for imprint can be produced using our DWL or EBL tools.

INL is equipped with e-beam lithography which has demonstrated resolution down to 7 nm.

A range of photoresist options has been validated

• positive tone PMMA 100 nm to 430 nm and bilayer PMMA processes for lift-off of nanostructures
• positive photoresists ZEP520 and AR-P 6200 for etching applications
• negative tone AR-N 7520 for etching of nanopillars, range 80 nm to 800 nm in thickness, achieving typically 50 nm lateral size for 200 nm photoresist thickness.
• Limited testing on HSQ negative tone resist for highest resolution and semiconductor applications
• Epocor/Epoclad epoxy resist for direct write of optical waveguides

The e-beam system accepts wafers of 3 inch and 200 mm in diameter, sample parts of irregular shapes fitting into a 76 mm circular holder, and glass masks 6 inch in diameter.

The e-beam exposure files are converted using Genisys Layout Beamer and can include proximity effect correction in dose factor and in shape

— Suss Microtec: High-throughput Coating & Development Process.

– Handling of round and square substrates up to 200mm.

– Thin, thick resists, polyimide.

– Precision edge bead removal.

– Process up to 25 wafers in one batch.

— Suss Microtec: Optical Exposure with Mask Aligner.

– Substrates up to 200 mm.

– Masks from 2″ to 9″ plates.

– Broadband wavelength: 365/405 nm.

– Modes of operation: Soft, Hard and Vacuum Contact, Proximity exposure and Flood exposure

– Automatic alignment and backside-alignment capability.

— Heidelberg: Exposure with Direct Write Laser.

– Substrates up to 200 mm.

– Minimum structure size: 700 nm.

– Autofocus: optically or pneumatically.

– Auto-measurement capability.

– Grey-level lithography with 128 levels.

— Obducat Eitre 8: Nanoimprint lithography system.

– Allows both thermal and UV nanoimprint lithography.

– Full area: 8-inch square.

— Vistec E-beam Lithography 

– Thermal Field Emission gun for operation at 50 and 100 kV and up to 100 nA beam current.

– Capability of writing on Si and other substrates (glass, metals, SiO2,) up to 200 mm size.

– Capability of writing 150-mm optical masks for contact and projection lithography.

– Write field up to 520 µm.

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