Lithography

Lithography has become a basic process in wafer processing. In the lithographic process, a photoresist is first uniformly applied to the substrate by spin coating or spraying. With the aid of a structured template, typically a chrome-coated glass mask, the open areas are exposed to UV light or particle irradiation, whereby the solubility of the resist changes. Depending on the resist and process control, a distinction is made between positive and negative resist. In the case of positive resist, exposed areas are released from the developer; in the case of negative resist, the unexposed areas are dissolved during development. After development, the further structuring of the substrate can be carried out by chemical or physical removal.

Litho 1

Process Steps

Resist coating

Spin and spray coating for structured 8 "wafers with low and high viscosity positive and negative resists (10 cSt to 5000 cSt) for coating thicknesses from 1.2μm to 60μm.

Exposure:

For exposure, a Maskaligner and a Widefield Stepper are available. Front and back adjustments are possible in the Maskaligner. Exposure can be at proximity distance or as contact exposure. In the Widefield Stepper, a resolution of 0.8μm is possible with a maximum field size of 50 x 50mm².

Litho 2

Development:

The development of the coatings can be carried out both by puddle as well as spray development.

Special resist applications:

Thick resist coatings
Lift-off processes

Equipments

Equipment Type  |  Producer
Stepper FPA-3000 iW | Canon
Mask Aligner MA200 Compact (FSA+BSA) | SUSS
Spin Coater ACS200 PLUS | SUSS
SVG90 S | SVG
Spray Coat   ACS200 PLUS | SUSS
Developer ACS200 PLUS | SUSS
SVG90 S | SVG
CDSEM CDSEM9260 | Hitachi