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About Simax

Simax provides a complete portfolio of engineering services for semiconductor manufacturing equipment and helps customers to optimize their lithography equipment for new and emerging applications. Simax' services include pre-owned equipment, engineering services, field support and applications services as well as financial services.

We support steppers and scanners from ASML and Nikon as well as Canon and other manufacturers for wafer sizes of 200mm and below. Simax also provides parts, parts and module repair, system refurbishment, equipment audits and deinstallations.

Our engineering and applications services support long-term use and optimization of lithography equipment anywhere in the world. The combination of first-class support with a cost-efficient operation increases the lifetime value of equipment and production lines, providing exceptional customer value.

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Best Solutions

Full Field Dose to Clear Technique

A significant part of a process engineer’s job is to develop simple and effective monitors that employ minimal non-productive equipment time - Dose To Clear or DTC is one such test.

Innovative Sub-resolution Technique

Successful process development, using existing equipment, extended beyond its defined specification limits is a tribute to a process engineer’s innovative creativity.

News

MEMS Metrology Part 3: Front To Back Alignment - the final frontier

Front to Back Alignment (FTBA) lithography has evolved over the past 10 years from contact printers utilizing infrared (IR) alignment and dual sided optical microscopes, to the current state of the art, ASML's “3D align” system.

Historically, FTBA overlay specifications were typically 2 to 3 micron, which defined the “outer limits” for device designers. This has all changed with the introduction of ASML’s “3D align” option, a stepper/scanner based FTBA system that pushes beyond these limits by an order of magnitude. This new capability opens up opportunities to designers, who can now develop high volume, high density, MEMS products that were previously only possible in small R&D quantities. A short animation describing how the ASML “3D align” works is available at this link.


So, what are the challenges? The main challenge, besides keeping the front side of the wafer protected whilst printing patterns on the back, is the verification of FTBA overlay. In the past, optical verniers visible in IR, were used and although error prone were deemed adequate for 2-3 micron design rules. Unfortunately, this is not the case when FTBA overlay performances pushes below 500nm, especially when one considers measuring this over a 600 micron wafer thickness. Researchers have experimented with electrical test methods, but these have proved unsuitable for a production environment. Etching alignment targets through the wafer has also proved not to be error free due to asymmetry effects. So how does one measure the error?

front-to-back-alignment


The metrology building blocks discussed in the previous articles suggest that self metrology should be possible. This is the subject of a paper by the Delft University. The paper explores the use of glass wafers, chrome omnimarkers, and rotating the wafers 180 degrees to solve the alignment beam angle and refractive index errors that confound the metrology.

For more discussion about the “final frontier” and other possible solutions, please This e-mail address is being protected from spambots. You need JavaScript enabled to view it.