Mask blanks “Made in Germany”
Materials with particular optical properties play an outstanding role in the chip manufacturing process. SCHOTT LITHOTEC AG, which has its main base in Jena, has taken over the world’s leading position in the growth of calcium fluoride monocrystals for the 157-nm lithography of the future. In addition the company is active in the components field at its Meiningen (Thuringia) facility. “We supply mask blanks as a high-tech product used as the basis for mask manufacture”, explains Dr. Peter Rudakoff, Manager of SCHOTT LITHOTEC AG’s Components Business Group in Meiningen. The mask blanks consist of high-purity fused silica substrates coated with a very thin layer of chromium and a photoresist. The mask manufacturers structure the mask blanks by exposing and etching them to produce the masks required. These masks are then used as the pattern for “exposure” of the silicon wafers.
The “mask blanks” are products of the highest quality that have to comply with the extreme requirements of the chip industry. To date this lucrative business has been dominated almost exclusively by manufacturers from the Far East. There is currently only one supplier worldwide for the highest qualities. It is no wonder, therefore, that purchasers are urgently waiting for new suppliers. “With the setting up of our Advanced Quality Line, known as AQL for short, we want to enter the champions league of mask blank suppliers and at the same time create the prerequisites for supplying larger quantities on a continuous basis,” says Components Business Unit’s sales manager Dr. Schneider-Störmann.
The 16,000 square meter premises, where at one time Robotron manufactured electronic components, instruments and hard disks, are ideal. There is also a pool of specialist labor that speaks for the location. As with chip production itself, the manufacture of materials and components make the highest demands on cleanliness. This means that appropriate care has to be taken, says production manager Michael Dietz, not only with clothing regulations, but also over the technical equipment, which, for example, ensures that there is permanent positive pressure and looks after the air quality in the clean rooms. At SCHOTT Lithothec microclimate boxes are being used to further minimize the particle level.
Well ahead on the “roadmap”
In spite of the difficult economic situation worldwide, and its impact on the computer and semiconductor industries, technological development is continuing to push ahead. For example, work is already in progress on the implementation of 157-nm lithography, which is set to come into use in about 2004 and should make 70 nanometer chip structures possible (1 nanometer is one millionth of a millimeter). The next generation, extreme ultraviolet (EUV) technology, is also already in preparation and could become reality from 2008 onwards. These steps are following a timetable which US companies first drew up in 1991 and according to chip structures, should be reduced in size by 30 percent every three years. All the processes required are coordinated with this objective. Driven on by global competition, the manufacturers have surpassed their own guidelines. Over the past 10 years, miniaturization has occurred on the average of two-year intervals. In other words, the chip generation changed in this period.