Nanoscale mechanisms of surface stress and morphology evolution in FCC metals under noble-gas ion bombardments

Abstract

Here, we uncover three new nanoplasticity mechanisms, operating in highly stressed interstitial-rich regions in face-centred-cubic (FCC) metals, which are particularly important in understanding evolution of surface stress and morphology of a FCC metal under low-energy noble-gas ion bombardments. The first mechanism is the configurational motion of self-interstitials in subsonic scattering during ion bombardments. We have derived a stability criterion of self-interstitial scattering during ion embedding, which consistently predicts the possibility of vacancy-and interstitial-rich double-layer formation for various ion bombardments. The second mechanism is the growth by gliding of prismatic dislocation loops (PDLs) in a highly stressed interstitial-rich zone. This mechanism allows certain prismatic dislocations with their Burgers vectors parallel to the surface to grow in subway-glide mode (SGM) during ion bombardment. The SGM growth creates a large population of nanometre-sized prismatic dislocations beneath the surface. The third mechanism is the Burgers vector switching of a PDL that leads to unstable eruption of adatom islands during certain ion bombardments of FCC metals. We have also derived the driving force and kinetics for the growth by gliding of prismatic dislocations in an interstitial-rich environment as well as the criterion for Burgers vector switching, which consistently clarifies previously unexplainable experimental observations.

Molecular dynamics simulations of cumulative helium bombardments on tungsten surfaces

“…The incident energy of a noble-gas ion in ref. [28] is much higher than that of incident He in our work, thus, one ion can generate two or three AIEs. However, in our work, more He atoms with low energy are required to induce one AIE.…”

Determination of Stresses in Incrementally Deposited Films From Wafer-Curvature Measurements

“…A large stress gradient can lead to significant curvature in the film when it is removed from the substrate and hence deformation in the desired device [17]. It is also noted here that if the film is grown under intense ion beam bombardment in a sputtering deposition, the effects of subsurface microstructural rearrangement [18] have to be taken into account in evaluating the residual stress in Eq. (5b).…”

Влияние Низкоэнергетической Ионно-Плазменной Обработки На Остаточные Напряжения В Тонких Пленках Хрома

“…Одним из методов воздействия на механические напряжения является ионная бомбардировка [7][8][9][10][11][12][13][14][15][16]. Она может создавать как растягивающие [8][9][10]15], так и сжимающие напряжения [7,10,13], и поэтому предоставляет широкие возможности по их регулированию.…”

“…Для определения влияния ионной бомбардировки на механические напряжения обычно применяются два метода: метод кривизны [7][8][9][10][11][12][13][14][15], использующий формулу Стоуни [18], и метод рентгеновской дифрактометрии [16,19]. Оба метода дают информацию лишь о величине напряжений, усредненной по толщине пленки.…”