Recent observations on „swirl defects” in dislocation-free silicon

Abstract

It is found that a small hillock arises in most cases prior to the appearance of an etch pit.There are various particular shapes of pits in the initial stage. Only on further etch attack these pits transform into the well-known flat-bottomed and triangular shapes. From this it is concluded that small stacking faults or related defects are responsible for the swirl-etch pit formation. Precipitation of oxygen or hydrogen around the defects may occur causing the initial hillock formation. Die Entwicklung von Swirl-Atzgruben auf versetzungsfreien Siliziumscheiben wurde genauer untersucht. Es zeigte sich, daD in den meisten Fallen dem Auftreten von Atzgruben eine Hugelbildung vorausgeht. Die Atzgruben selbst zeigen im Anfangszustand verschiedenartige Formen. Erst nach weiterer Atzung gehen sie in die bekannten dreieckigen Flachgruben u b x . Wir schlieBen daraus, daD kleine Stapelfehler oder damit verwandte Defekte die Swirl-Atzgruben hervorrufen. Eine eventuell an diesen Defekten vorliegende Sanerstoffoder Wasserstoffausscheidung konnte die anfangliche Hiigelbildung bewirken.

Impact of Research on Defects in Silicon on the Microelectronic Industry

“…This problem and its solution was an excellent first example of cross fertilization between investigations in the industry and academic research: The matter of unexplained leakage currents in dislocation-free materials was studied in parallel in several industrial laboratories at Siemens [2], Philips [3] and Bell Laboratories [4] and it became clear in all three cases that the root cause for the leakage currents were not single dislocations but so-called swirl defects which by high voltage TEM were identified to be complexes of extrinsic dislocation loops (Fig. 2).…”