Ball Semiconductor Inc says it has now fabricated a working transistor on the surface of a one-millimeter silicon sphere – a first, the company claims. Allen, Texas-based Ball began talking about its plans for spherical semiconductors back in June, saying that the technique offered a potential 90% cut in integrated circuit manufacturing costs (CI No 3,441). Most of that saving comes from the use of hermetically sealed tubes in place of clean rooms and from reducing processing times from months to days. Now the company has produced a five-micron NMOS transistor with electrical characteristics equal to those of a traditional wafer transistor. Ball says the move both proves its theories and establishes the fundamental processes it needs to embark on a full-scale pilot manufacturing line for producing diodes, transistors and select sensors. Ball created the spherical lithography processes needed for the part, a resist-coating process and chemical vapor deposition for depositing a thin aluminum surface onto the sphere. It is currently working on producing an electrically functioning IC on the sphere.
