Observation and electronic characterization of lsquo;lsquo;newrsquo;rsquo;Eprime; center defects in technologically relevant thermal SiO2on Si: An additional complexity in oxide charge trapping

摘要

Using electronhyphen;spin resonance (ESR), we demonstrate that severalErsquo;variant precursors exist in a variety of technologically significant thermally grown thin SiO2films on Si. TheErsquo;variants include two varieties with the ubiquitousEggr;rsquo;line shape (zerohyphen;crossingg=2.0005, O3equiv;Sisdot;) and a second very narrow line shape (zerohyphen;crossingg=2.0019, structure unknown). We tentatively label theg=2.0019 defect EP for provisionalErsquo;and distinguish theEggr;rsquo;variantsEggr;nrsquo;(neutral) andEggr;prsquo;(positive). We combine ESR, capacitance versus voltage electrical measurements, and charge injection sequences to compare the electronic properties of the defects. We find that paramagnetic EP defects are positively charged while paramagneticEggr;rsquo;centers can be either positively charged or, under some circumstances, neutral. We find that EP precursors have a very large capture cross section for holes (sgr;=10minus;13cm2) and that paramagnetic EP defects have an even larger capture cross section for electrons (sgr;=10minus;12cm2). Both EP capture cross sections are an order of magnitude greater than those of theEggr;prsquo;defects. We find that EP centers are distributed much more broadly throughout the oxide than either theEggr;prsquo;orEggr;nrsquo;defects. We also find a two order of magnitude variation in EP density dependent upon processing variations. In addition, EP centers, unlike theEggr;rsquo;variations, are not stable at room temperature. With their large capture cross section for holes and even larger capture cross section for electrons, EP defects may be relevant to device reliability and charge trapping under conditions of a low, relatively pure hole fluence such as in hot hole injection in shortnhyphen;channel metalhyphen;oxidehyphen;semiconductor fieldhyphen;effect transistors.