Mechanisms of silicon damage during N2/H2 organic etching for fin field-effect-transistor CMOS

Abstract

The authors investigated the mechanisms of Si p+/n junction damage caused by N2/H2 plasma during organic implantation mask etching. The junction leakage current of a p+/n-well diode rose when the authors reduced the plasma-source power and increased the radio-frequency (RF) bias power, whereas it did not rise after they increased hydrogen ratio of the N2/H2 plasma gas. This indicates that ion energy and dose have a greater influence on junction damage than the density of hydrogen radicals does. Accordingly, the authors suggest that a high etching rate and low ion energy, which correspond to a high hydrogen ratio and low RF bias, are the best combination for low-damage organic block etching.

Characterization techniques of ion bombardment damage on electronic devices during plasma processing—plasma process-induced damage

“…The impact of remaining defects on the leakage in the pn junctions was experimentally clarified. 44,127) Another effect by PPD is an increase in the resistance due to the presence of defects in the channel region of a MOSFET. 128) These defects decrease the drain current of the damaged MOSFET device, i.e.…”

“…Current-voltage. Current-voltage (I-V ) measurement is usually conducted for PPD evaluation using the Schottky-contact metal-semiconductor (MS), 38,70,[86][87][88]171,172) pn junction, 44,127) and MOS structures. In I-V measurements, tunneling current or junction leakage is monitored.…”

“…16(b). Morimoto et al assigned 127) the presence of PPD defects after N 2 /H 2 plasma etching by monitoring the pn junction leakage current via the conduction process (1) in Fig. 16(b).…”

Improvement of the plasma‐induced defect generation model in Si substrates and the optimization design framework

“…The recessed depth from the original plane is defined as a Si recess d R . The remaining defects play a role as carrier trapping and detrapping sites, which degrade the electrical performance of MOSFETs.…”

“…Despite advancements in plasma processing, the degradation of material properties due to plasma exposure—plasma process‐induced damage (PID)—has become a key issue . In general, PID is classified on the basis of the mechanisms of its generation such as “physical damage,” “charging damage,” and “radiation damage.” Physical damage is induced by high‐energy ion bombardment on Si substrates or other material surfaces. Charging damage induced by the conduction current results in the degradation of the performance and reliability lifetime of MOSFETs .…”