MA8 Gen5 Mask Aligner

Top-side alignment (TSA)

Where lithographic processes require the alignment of structures on only one side of the device wafer (e.g. RDL, micro bumping, and similar techniques), top-side alignment is used to align the fiducials on the mask with those of the wafer. Depending on substrate properties, this can be achieved either using stored position data for the wafer or through live image alignment, as in the DirectAlign® system invented at SUSS.

Highlights

• Mask aligner for the highest level of alignment precision
• Clear and stable pattern recognition even under poor contrast conditions

A mask with a certain structure is aligned with the wafer in very close proximity (thus “proximity” lithography). During exposure, the shadow cast by the mask structure is transferred to the wafer. The resulting exposure quality depends on both the precision with which the mask and wafer are spaced apart and the optical system used for exposure.

Being fast and suited to flexible implementation, this method is regarded as the most cost-effective technique for producing microstructures down to 4 µm in size for 300 mm tools and down to 3.5 µm and 3 µm for 200 and 150 mm tools, respectively. With contact exposure, resolutions in the sub-micron range can be achieved. Typical areas of use include wafer-level chip-scale packaging, flip chip packaging, bumping, MEMS, LED, and power devices. The systems are deployed in high-volume production as well as in industrial research.

The mask aligners supplied by SUSS are based on proximity lithography.

Features & Benefits

• Superior resolution as a result of diffraction-reducing optics
• Process stability through the use of microlens optical systems

MO Exposure Optics® is a unique illumination optics specifically designed for SUSS mask aligners. It is based on micro-lens plates instead of macroscopic lens assemblies. A simple plug & play changeover allows for a quick and easy changeover between different angular settings including the functionality of both classical SUSS HR and LGO illumination optics.

The telecentric illumination which is provided by the MO Exposure Optics improves light uniformity and leads to a larger process window. In consequence, this causes yield enhancements. MO Exposure Optics also decouples the exposure light from the lamp source thus small misalignments of the lamp do not affect the light uniformity. A decoupled light source saves setup and maintenance time and guarantees uniform illumination conditions during the full life-time of the lamp.

Highlights

• Excellent light uniformity over full exposure field
• Stable light source
• Customizable illumination by means of illumination filter plate exchange
• "DUV-ready" process capabilities with fused silica micro optics
• Special "down-sizing kits" for light compression to smaller wafer sizes

Auto Alignment is based on a motorized alignment stage. The COGNEX® based pattern recognition software automatically recognizes wafer target locations and controls the movement of the alignment stage. Coupled with SUSS‘s DirectAlign® accuracies down to 0.25 μm can be achieved. Auto Alignment enables the highest repeatability of process results coupled with optimized throughput and minimum operator intervention.

Simulation of lithographic processes

A simulation of lithographic processes makes the selection of optimal settings for process parameters possible without long-winded trial-and-error sessions. The multi-functional simulation software of lithographic processes “Lab”, which SUSS distributes together with the supplier, GenISys, first and foremost allows the operator better process control. It offers all the required simulation functionality for an integrated design and process development, verification, and optimization. At the same time, it covers all the process steps, from illumination shaping and mask layout optimization up to photoresist processing. Additionally, modern 3D simulation functions improve the model visualizations.

The combination of MO Exposure Optics and the SUSS optics custom-developed optical models in the Lab facilitates customer-specific design optimization of the exposure filter plates, which in turn leads to an improvement in pattern fidelity.

Highlights

• Complete simulation of the mask aligner lithographic process
• Adjustable illumination parameters (collimation, spectral composition), custom-developed for all SUSS optics
• Fast and flexible visualization and quantitative predictions in 1, 2 and 3D

Imprint lithography represents a cost-effective and highly reliable means of transferring three-dimensional nano- or micro-scale patterns onto a wide variety of substrates.

For the imprint, a stamp is brought into contact with a photosensitive material on the substrate. The photoresist fills out the three-dimensional pattern of the stamp and then solidifies under UV light. Parameters such as pattern topography, structure resolution and aspect ratio have a considerable influence on the process quality.

Thanks to its compatibility to well-established semiconductor processes, imprint lithography plays a key role in the development and production of DFB lasers, HB LEDs, wafer-level cameras and MEMS.

SUSS solutions for imprint lithography are based on manual mask aligner platforms and support a wide range of materials and substrate with sizes up to 200 mm. Furthermore, SUSS platforms provide the capability of aligning and levelling stamps to substrates, as required by many imprint applications. Imprint equipment can also be retrofitted to SUSS mask aligners which are already in the field.

Depending on process requirements, SUSS offers different imprint technologies on its mask aligners.

• Imprint Lithography Brochure
• Imprint Lithography Webpage

Tooling for bonding of two substrates in the mask aligner.