Characteristics and origin of emitter-collector shorts, or “pipes”, in multi-emitter power transistors

Quantified Conditions for Emitter‐Misfit Dislocation Formation in Silicon

“…The influence of dislocations on impurity diffusion and the electrical performance of Si devices has been reviewed extensively by Lawrence (11). Depending on the stability and electrical activity of induced dislocations and whether or not residual metal impurities and structural imperfections exist in the Si prior to emitter diffusion, the following effects have been correlated with misfit dislocations: (i) reduced transistor current gain (1,2,12,13), (it) emitter-collector shorts and excess leakage (1,12,(14)(15)(16)(17)(18)(19), (iii) high junction leakage currents (1,11,(20)(21)(22)(23), (iv) increased low frequency noise figure (21), and (v) variable temperature dependence of transistor current gain (21). Therefore, the detrimental effects of phosphorus emitter-induced misfit dislocations have been well documented.…”

SEM and TEM observations of emitter‐collector pipes in bipolar transistors

“…The white EBIC contrast at pipes was often accompanied by adjacent black contrast due to the recombination of electrons at parts of the dislocation in the base region.Emitter-collector pipes, defined as low resistance paths locally connecting the emitter to the collector have long been recognized as a cause of low yields in the fabrication of bipolar devices (Miller, 1960;Barson et al, 1969;Plantinga, 1969). Various techniques have been developed to investigate the formation of pipes, including bevelling and staining (Barson et al, 1969), Sirtl etching with and without applied bias (Plantinga, 1969;Juleff, 1973), anodic oxidation (Kulkarni et al, 1972;Tice et al, 1973; Set0 et al, 1973), electron-beam-induced conductivity (EBIC) studies in the SEM coupled with TEM observations (Varker & Ravi, 1977), and Sirtl etching coupled with high voltage electron microscopy (HVEM) (Foll & Kolbesen, 1977). The earlier techniques, although relatively non-destructive are indirect, that is the electrical behaviour of a particular pipe may not be obtained directly and correlated to a specific crystal defect.…”