The 1970s


In 1972, Dr. Haldor Topsøe decides to divest Topsil from his other business activities which are related to catalysts. Two years later, Topsil engineers come up with a great idea. They intend to develop a new product.

The semiconductor industry is in the wake of introducing a new kind of components, thyristors, that are to play a key role in transforming high voltage alternate current to direct current. The development of thyristors requires silicon uniformity, precision and reliability up to unprecedented level in order to function. Theoretically speaking, several experts say, neutron transmutation doping of silicon might be a viable road to achieving these material properties.

In 1974 Topsil therefore convinces researchers at Risoe National Laboratory (DK) to conduct some reactor experiments. During the initial discussions, skeptics amongst scientists make a point that tests are likely to result in radioactive and therefore useless silicon crystals. Topsil, however, is true to the idea, backed by a customer, later known as ABB, which has a keen interest in pushing the limits of silicon.

The first test proves sceptics to be wrong. The neutron transmutation doped (NTD) test crystal is only slightly radioactive and displays exactly the material properties desired. After only five days, the wafer is no longer radioactive and can threfore be returned to Topsil.

One year later, this technique is widely accepted in the silicon industry for the manufacture of the most advanced high power semiconductor components. The diameters of Topsil's silicon wafers are now slightly bigger, from 2 to 2½ inch. End of the decade, Topsil silicon wafers pass the diameter of 3 inch.

Additional information: 
Four decades later Topsil has succeeded in maintaining its position as the global market leading supplier of NTD silicon, which constitutes the vast proportion of the company revenue.  The Czochralski manufacture, on the other hand, is closed down in the mid-1970s, as the manufacture proves not to be cost-effective.