SCHOTT solutions no. 1/2011 > Machine Vision

Unlimited Possibilities

MORITEX, the company that belongs to SCHOTT Group, manufactures highly advanced inspection systems. One example is a machine vision inspection system, which allows for cutting edge research to be performed in the area of MEMS technology.

Yutaka SuzuKi & Takeshi Harada

MEMS, or Micro-Electro-Mechanical Systems, are used in all types of everyday devices, such as automobiles, mobile telephones and home game consoles. MEMS use a variety of micromachining technologies to place micron-scale parts on a single substrate. MEMS devices are tiny, highly precise, and offer superior energy-saving features. They make it possible to manufacture ultra-small actuators and many other types of sensors. They are key devices in next-generation manufacturing, with cooperative industry-university research proceeding as a national R & D project. The Japanese company MORITEX, a member of SCHOTT’s Lighting and Imaging Business Unit, uses its expertise in optics to manufacture and market a wide variety of specialized devices, including inspection equipment. One of these devices was selected by the BEANS G Device Center in Tsukuba that conducts MEMS research as a national R & D project: ”Our machine vision inspection system makes use of the fact that silicon transmits infrared light and can automatically check MEMS devices for defects. The unit we delivered to the BEANS G Device Center is customized to automatically perform surface inspection of a 200 mm wafer using visible light. If this equipment works out well, we anticipate a considerable up-tick in adoption of this machine vision inspection system in MEMS device manufacturing and by semiconductor makers,” says Junya Inoue, the sales representative in charge of the inspection system.

In 2010, the BEANS project added a new R & D topic on the development of an advanced sensor network system and environmentally friendly processes, and launched G device@ BEANS. This new research initiative is aimed at developing a system with a smart clean room and advanced 8-inch MEMS production lines. The system will allow for a large number of high-performance MEMS sensor modules to be used in the clean room and MEMS production line for real-time monitoring of energy usage conditions, controlling of the air conditioning system, etc. With respect to low environmental impact processing, R & D work is being pursued on technologies such as the use of an alternative gas for deep etching of the silicon substrates used as MEMS materials and low temperature wafer-level packaging. Furthermore, their research encompasses constructing high-quality processes for the 8-inch MEMS production lines, accumulating process recipes compatible with new materials and new structures, improving the level of design technology for controlling process margins, and investigating process technology based on environmentally friendly, biocompatible polymers. In December 2010, a smart clean room and 8-inch MEMS prototype station were completed at the Research Center for Ubiquitous MEMS and Microengineering, housed in the research base of the independent administrative agency National Institute of Advanced Industrial Science and Technology (AIST) in Tsukuba East. This 8-inch MEMS line consists of two lines. The front-end processing line includes wafer cleaning, lithography, oxidation and diffusion, deposition, and etching. The back-end processing and testing line covers everything from chip and wafer-to-wafer bonding and wire bonding up to testing, including evaluations of the processed wafer profiles and the electrical properties of devices, etc. Together, these comprise a fully integrated 8/12-inch MEMS line. This line supports fine-pitch processing down to 0.35 µm line widths as well as three-dimensional micromachining, and is capable of processing everything from sensors and other time-tested MEMS devices to advanced devices.

The optical microscope automatic inspection system is based on the machine vision technology at Moritex. This system is used to automatically inspect the MEMS devices at wafer level, and evaluate yield and manufacturing variation. Being able to acquire such equipment in an order of magnitude lower in cost than semiconductor equipment was very attractive. The center is convinced that this unit will play a major role in inspection on its 8-inch MEMS line. <|