Photolithography

With photolithography it is possible to transfer a desired structure into a thin film on a substrate or into a substrate directly with the help of a photosensitive (UV) polymers and a mask aligned to the substrate.
For example structures in metal or metal oxide layers on glass or Silicon substrates.

For realizing complex structures the above steps are repeated with care for a proper alignment of the structures.
In Device Processing several exposure tools are available: Karl-suss MA8 , ORC and an Ushio photo-aligner.

Karl-suss MA8

The MA 8 is a versatile exposure tool. It can handle rectangular, square and circular substrates up to 6 inch.
Two mask holders are available. Aligning is done with two joysticks, serving a motorised x, y, theta alignment stage with a wedge error compensation system. Programs are easily made and can be saved. Wedge error compensation is done automatic with or without contact between mask and substrates (with reference balls).
Alignment gap is programmable from 0 to 300 mm.
Aligning without microscope is done on a LCD display using EVS (Enhanced Video System).
These features, together with the CIC1200 lamp unit, are making 1 µm dimensions possible.

 

ORC

The ORC is a suitable exposure tool using a parallel beam of light. It can be used for bottom as well as top-side exposure and both in the contact mode or in the proximity mode.
Due to the high parelellism of the light it is very well suited for exposure of 3-dimensional objects.
Substrate size is very flexible. It can vary from very small to 21 inch square.
The smallest dimension of patterned structures that can be fabricated with this tool are about 1 µm.

 

Ushio photo aligner

An Ushio UX-1000 SM-AHG01 projection system is available in the cleanroom.
From now on the term photoaligner will be used for this equipment. The photoaligner is situated in a class 100 environment.
It can be used in several exposure modes and has a maximum exposure area of 6'' square. It is a system used in the LCD industy for aligning the polyimide layer on which liquid crystal molecules orient. Areas of application of the photoaligment technique include LCDs, polarisers and retarders.
The photoaligner is a versatile exposure tool. The wavelength regime is 200 nm to 400 nm. With the use of dedicated band pass filters (254, 313 or 365 nm) or a cut off filter (300nm) it is possible to use a small area of the whole wavelength area.
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