Lithography

Lithographic techniques enable precise structuring of coatings on optical substrates. This allows different coating systems to be combined on a single surface or specific areas to be selectively coated. All lithography steps are performed entirely in a cleanroom under controlled conditions to prevent particle formation.

Fig.1:Lithographically structured coating

a)Lithographically structured coating

b)Measured height profile of a lift-off edge

Process Principle

Lift-Off Process

Etching Process

Production Capabilities

Additional Processing Options

Application Areas

Process Principle

Lithography is based on the local masking or exposure of substrate regions using photoresist. After exposure and development, defined structures are formed in which coatings are either deposited or removed. For combining different coatings, we use the lift-off process.

Fig.2:SEM image of a coating edge produced by lift-off

a)Top view

b)In FIB cross-section (with residues from sample preparation)

Lift-Off Process

A photosensitive resist is applied to the substrate and exposed through a mask. After development, the resist remains only in the intended areas. The subsequent coating is deposited over the entire surface. When the resist is removed, the unwanted coating regions lift off together with it.

This method enables fine structures with sharp coating edges and is well suited for dielectric coating systems used in laser optics. The resulting structures are precisely defined and laser-resistant, making them suitable for high-power applications.

Fig.3:Lift-off process

Etching Process

In the etching process, the substrate is first coated over the entire surface. A photoresist pattern is then applied, exposed, and developed. The unprotected areas are selectively etched. This method is particularly suitable for metallic layers such as chromium or aluminum.

Fig.4:Etching process

Production Capabilities

Standard material: fused silica; other materials on request
Substrates up to 8" (200 mm) diameter
Thickness down to approx. 0.5 mm
Preferred fabrication on full plates; subsequent singulation possible
Structure sizes from approx. 5 µm
Layer types: structuring of metallic and dielectric coatings
Cleanroom manufacturing: ISO class 7 for high reproducibility

Fig.5:LAYERTEC employee

Fig.6:LAYERTEC lithography cleanroom

Additional Processing Options

Double-sided structuring
Combination with laser or ultrasonic drilling, sawing, or beveling
Adaptation to customer-specific geometries
Coating quality inspection (microscopy, reflection/transmission measurement, thickness analysis)

Application Areas

Optical components with locally differentiated functionality (e.g., AR/HR combinations, polarization zones)
Structured filters and masks for high-power lasers
Prototypes and small series for research, industry, and metrology

Examples of lithographically structured optics can be found on our product page: Lithographically Structured Coatings.