Sodium Contamination in SiO₂ Films Induced by Plasma Ashing

Abstract

The scattering of HeZ+ ions from molecular nitrogen has been studied in the angular range 0-20' and in the energy range 200-600eV. Elastic, simple inelastic, and single-charge-transfer scattering were observed using energy analysis of the scattered He ion to distinguish among the different processes at each observed scattering angle. The data are presented in the form of exit-channel spectra and cross section against reduced scattering angle. For scattering without electron capture, a binary collision model (in which one of the two nitrogen nuclei exchanges momentum with the projectile, the other acting as a 'spectator') is adequate up to a reduced scattering angle of approximately T = EO = 6000 eV deg for describing the average elastic energy transfer. Evidence for spin-selection rules in low energy ion-molecule collisions was observed. For He2+ + N z collisions the charge-transfer processes had the largest cross section throughout our range of energies and angles. particularly at the larger value of T. The exit-channel spectra for N, targets are compared to those taken for Ne and Ar targets and strong similarities are noted. Charge-transfer processes leaving the outgoing He' in its ground state produced very high excitation of the targets (about 45 eV above the ground state for N,), showing a preference for small values of IQI. where Q is the energy defect.

Mobile ion-induced data retention failure in NOR flash memory cell

“…The amount of sodium is found to be increased after photoresist removal by plasma ashing and subsequent strip. In fact, plasma ashing has been identified as a strong candidate for sodium contamination [6], [7]. In back-end processes, there is a plug implantation process, which fills photoresist into a bitline contact, so the sodium ions are more likely to be introduced through the contact during the photoresist filling process.…”

Resist stripping in an O2+H2O plasma downstream

“…6 However, the O 2 +-CF 4 plasma downstream also has a serious defect, in that some materials used in semiconductor devices such as poly Si, Si0 2 , and SiN, are etched slightly during the resist stripping. Most of the radiation damages are caused by the incidence of charged particles and imbalance of plasma potential in the vicinity of the sample wafer during in situ plasma processing.…”

Resist-related damage on ultrathin gate oxide during plasma ashing

“…Also in order to exclude possible contamination from photoresist, bias-temperature-stress (BTS) measurements were performed for those samples with resist overlayer. No flatband voltage shift is detected from the high frequencymeasurement (data not shown), suggesting that this damage is not caused by mobile ions in the resist [8]. Actually, the radial distribution of across the wafer shown in Fig.…”