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Spherical semiconductor radio temperature sensor


Spherical LSI, a new technology that overthrows common sense

More than 40 years before in around 1960, the semiconductor integrated circuit, LSI was created, is made from flat silicone crystals, by electrically connecting many transistors on them. In order to form minute transistors accurately, it had been believed that the flat surface of the silicone crystals was necessary.

However, °»ball semiconductor°… a new technology that can overthrow the conventional idea has emerged and attracted much attention. The Ball Semiconductor Company founded in 1996 (Texas, the U.S.A., President ? Akira Ishikawa) invented a technology for forming spherical silicone crystals with a diameter of 1mm, and the basic technology enables us to form LSI on the surface of the crystals.

Figure 1 shows the pictures of the different structures of the ball semiconductors connected electrically and laid on the wiring base. Needless to say, experts couldn°«t believe their eyes when they saw these pictures. Even forming spherical silicone crystals with sufficient reproducibility was something hard to believe.

The silicone sphere is created by melting granular silicone materials in the air and crystallizing them when they fall for their own weight. In the conventional process of LSI formation, a thin film is first formed on the surface of silicone and the film is repeatedly made into minute pieces using the photographic technology called photolithography. The Ball Semiconductor Company invented this LSI-formation technology in order to apply it to the creation of silicone sphere, and succeeded in forming an integrated circuit on the surface of the ball semiconductor.

As a ball semiconductor is spherical, it has an advantage from having larger area for integrated circuits. Also, by taking the benefit of the spheres with a diameter of 1mm as a production unit, the ball semiconductor would be suitable for producing a little account of carious products small manufacturing facilities. Furthermore, it is expected that the shape of sphere will be utilized and applied to many different sensors.

Yamatake Corporation, which is the top manufacturer of sensors and control system, has progressed a project to develop wireless temperature sensor with a diameter of 1mm in collaboration with Ball Semiconductor Company by combining their own temperature sensor technology and the ball semiconductor technology (Refer to p.64 ? 65 °»Human Interview°… for Yamatake Corporation).

Figure 2 shows the appearance of a sample of the radio temperature. A coil made by golden thin film surrounds the sphere and is used as an antenna to exchange signals with detecting equipment in the distance by the electric wave. The energy required for integrated circuits is sent to this coil through the electric wave and turned into electric power. Therefore, the temperature sensor does not need batteries, which allows the system to take the earth°«s environment into consideration. It is implied a coil attached on the surface of a sphere has transceiver efficiency about 5 times higher than the one on a flat surface.

Figure 3 indicates a magnified photograph of a part of the integrated circuits. The transistor circuit is visible underneath the silver coil.

Yamatake Corporation is currently promoting the evaluation of new sensors in pursuit of utilizing the ball manufacturing and modeling technologies we have acquired in business through our study and development of the temperature sensor.

Have you all readers ever heard of the word °»ubiquitous°…? This is an English word which is adjective with a meaning of °»every time, everywhere°…. This word is often used these days, as people in the field of information communication are aiming at offering °»ubiquitous°… environment in the near future. The development of the radio temperature sensor system to which the engineers at Yamatake Corporation and Ball Semiconductor Company devote themselves, might realize the °»ubiquitous°… in the field of environmental measurement first. Looking at a mysterious picture of the earth-like ball semiconductor makes me have such expectation.

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