ASML 4022.455.1103 Rotator Beam OR BS Assembly

The ASML 4022.455.1103 is a rotator beam assembly designated OR BS (optical rotator / beam splitter) used in the illumination path of ASML steppers. This assembly provides precise rotation of the beam polarization or wavefront orientation, enabling advanced illumination modes such as dipole, quadrupole, and annular shaping. It also incorporates a beam splitter for sampling the beam power.

Optical and Mechanical Specifications

• Part Number: 4022.455.1103

• Type: Rotator beam with beamsplitter (OR BS Assy)

• Wavelength Range: 248 nm and 193 nm

• Rotation Range: 0°–360° continuous

• Rotation Resolution: 0.1° (stepper motor driven)

• Beam Splitter Ratio: 90/10 (transmission/reflection) for sampling

• Material: Fused silica with multilayer dielectric coatings

• Clear Aperture: 50 mm diameter

• Wavefront Distortion: < λ/20 at 193 nm

• Actuator: Piezoelectric rotary stage with encoder

Functional Description

The assembly rotates the incoming beam’s polarization or phase profile under computer control. The rotation is achieved via a precision air-bearing stage driven by a piezo motor. An integrated rotary encoder provides closed-loop positional feedback. The beamsplitter diverts a small fraction of the beam to a power monitor, enabling real-time dose control. The entire assembly is housed in a sealed enclosure with purge ports to maintain optical cleanliness.

Installation and Alignment

Mount the assembly on the optical bench using the four M6 mounting holes. Align the input aperture to the incoming beam using a HeNe alignment laser. The output beam must be centered on the subsequent optics. Connect the motor driver and encoder cables to the stepper’s control cabinet. After mechanical alignment, perform a calibration routine that sets the zero position and compensates for any eccentricity.

Performance Verification

Verification includes checking the rotation accuracy using an autocollimator and verifying the beam splitter ratio using a power meter. The wavefront error is measured with an interferometer. Any deviation beyond the specified tolerance may require readjustment or recoating of the optical elements.

Maintenance and Reliability

The air-bearing stage requires a constant supply of clean, dry air at 5 bar. The purge gas must be maintained to prevent contamination of the coatings. The motor and encoder have a lifespan of 10,000 hours; replacement kits are available. Routine inspection of the optical surfaces is recommended every 6 months.

Integration with Stepper Illumination

This rotator assembly works in conjunction with the illumination control software, which selects the rotation angle based on the desired illumination mode. It is fully compatible with PAS 5000/2500 and TWINSCAN illumination systems. The beam splitter output is used for dose feedback, ensuring exposure consistency.

Environmental and Safety

RoHS compliant and designed for cleanroom use. The assembly is class 1 laser product when enclosed. Operating temperature 20°C–24°C, humidity < 60%.

Technical Support and Documentation

ASML provides a detailed installation manual, optical alignment procedure, and maintenance schedule. Spare parts including the beamsplitter and encoder are available. On-site alignment service can be arranged.

Conclusion

The ASML 4022.455.1103 Rotator Beam OR BS Assembly is a precision optical component that enables flexible illumination patterning for advanced lithography. Its reliable actuation and stable optical performance contribute to achieving optimal exposure results.