Mirror-polished Si Research Articles

Characterisation of mirror-polished Si wafers and advanced Si substrate structures using the magic mirror method

Makyoh, the magic mirror method, has proven to be one of only a few production-worthy surface characterisation tools. This technique, very simple and non-destructive, transforms latent damage, scratches, waviness and other flaws on mirror-like surfaces into visual images. It has recently been used to characterise highly finished, mirror-polished, large-diameter Si wafers for ultralarge-scale integration (ULSI) applications and III-V compound semiconductor wafers, replacing the laborious, unstable, naked-eye wafer inspection line. The authors studies have shown that the technique is also very useful for optimising various wafering processes and monitoring various process steps required to manufacture advanced substrate structures such as silicon-on-insulator, silicon-germanium alloy-on-silicon, etc for future devices. It has been successfully applied to characterise various Si wafers used in ULSI applications with the highest finish. This paper describes the recent development of the method, reviewing some of the results obtained in the evaluation of mirror-polished Si and compound semiconductor wafers and of complex substrate structures for ULSI device fabrication processes.

Characterization of polished surfaces by “Makyoh”

Characterization by “Makyoh”, the magic mirror metho, has been proven to be very effective in detecting various flaws on mirror surfaces and also in controling mirror fabrication processes: state-of-the-art processes. Makyoh, a many-centuries-old simple concept, offers a very simple and non-destructive surface analyzing method which transforms latent damages, scratches, waviness and other flaws on mirror-like surfaces into visual images. It has a sensitivity of picking up undulations of an order of a few nm over a half mm span and is the most suitable method to characterize highly finished mirror-like surfaces with the extreme perfection of large areas, i.e. mirror-polished Si wafers for ULSI, hard discs, liquid crystal display glasses and other substrates. The Makyoh method has replaced the laborious and unstable naked-eye wafer inspection lines. It has also been proved to be effective in monitoring wafer processes like thermal and epitaxial processes.

Characterization of polished mirror surfaces by the “Makyoh” principle

“Makyoh”, a holy wonder mirror in religious world for centuries from ancient ages specially in the Far East, has now been polished and brushed up to become a powerful scientific tool, the “Makyoh visualizer”. It is a very simple, non-destructive and no-contact surface analyzer which transforms latent damages, scratches, waviness, etc., on mirror-like surfaces into visual images. It is so sensitive that it can pick up the very slight undulations of some 10 Å over a distance of about 0.5 mm. It is thus very effective to check the quality of highly finished mirror-like surfaces which have to be perfectly flat over large areas, i.e. mirror-polished Si wafers, hard discs, etc., and also for monitoring the entire mirror processes. The visualizer has been actually introduced in the on-line monitoring of Si wafer production lines for several years now, and has proved itself worthwhile, replacing laborious and instable naked eye inspection lines.