Crystal defects and junction properties in the evolution of device fabrication technology

Abstract

In this paper, the correlation between dislocation density and transistor leakage current is demonstrated. The stress evolution and the generation of defects are studied as a function of the process step, and experimental evidence is given of the role of structure geometry in determining the stress level and hence defect formation. Finally, the role of high-dose implantations and the related silicon amorphization and recrystallization is investigated.

Electrical and microscopy analysis of dislocations in present generation devices

“…However while in the transistor arrays the defects affect the N + areas, in the diodes the defects affect both the Pwell and Nwell areas. In a previous work we demonstrated the link between the dislocations and the channel leakage in the transistor [4]; now we show the link between the dislocations and the leakage in the diodes in the same manner. A statistical correlation was established between the measured junction leakage and Secco etch pits by a systematic inspection of the leaky diodes A very good correlation is obtained (Fig.…”

“…Vice versa, the narrow transistor arrays start to develop the first dislocation just after a few oxidations of the STI without any implantations. In fact these structures have a higher corner number than the diodes, and also the spacing and the width of the active area are smaller; so from our previous experience we know that they are more prone to develop dislocations [4]. Therefore, in these structures the mechanical stress piled up with the STI formation and the subsequent oxidations is enough to form dislocations.…”

A new built-in screening methodology to achieve zero defects in the automotive environment

“…The correlation between the presence of crystal defects and the increase of the transistor leakage current by various orders of magnitude is reported in the literature [2,3]. For this reason, screening for crystal defects is usually accomplished by measuring the drain leakage current when the device is biased under subthreshold conditions after applying a high voltage pulse to the drain terminal.…”

“…During the lifetime of a device, crystal defects can coalesce or act as a gettering site for dopant atoms and contaminations. This can result into the formation of local highly conductive paths, which under some circumstances can heavily affect the performance of the integrated circuit [2,3].…”

In situ screening techniques for defective oxides in devices for automotive applications

“…This can result into the formation of local highly conductive paths, which under some circumstances can heavily affect the performance of the integrated circuit. The correlation between the presence of such defects and the increase of the transistor leakage current by various orders of magnitude is reported in literature [9][10]. For this reason, screening for STI defects is usually accomplished by measuring the drain leakage current while biasing the device under sub-threshold conditions, after application of a high voltage pulse to the drain terminal.…”