Application and further development of ion implantation for very large scale integration. Pt. 2

Ion implantation, used as a dopant technology, provides very well-controlled doping but is dependent on the usual masking techniques. For purposes of pattern generation, it would be desirable to utilize the digital controllability of a finely-focused ion beam. In this report, the suitability of a finely-focused ion beam for the purpose of direct writing implantation has been investigated. For this study, an ion accelerator was equipped with a computer-controlled fine-focusing system. Using this system it was possible to implant Van-der-Pauw test structures, resistors, and bipolar transistors, which were then electrically measured. The smallest line width was approx. 1 μm. A disadvantage is represented by the long implantation times resulting with present ion sources. Another VLSI-relevant area of application for this finely-focused ion-beam-writing system is photoresist exposure, as an alternative to electron-beam lithography, making possible the realization of very small structures without proximity effects and with a significantly higher resist sensitivity. (orig.)