Phase transformation during silica cluster impact on crystal silicon substrate studied by molecular dynamics simulation

Journal of Applied Physics

Guo

2008

Self Cite

Molecular dynamic simulation is applied in analyzing the deformation of silicon surface under the impact of large silica cluster. The mechanism of such a deformation is largely different from the cases of ion bombardment and indentation. With the impact of large silica cluster, the silicon surface is extruded due to the combinational effects of thermal spread, phase transformation, and crystallographic slip. It is found that thermal spread is the most significant one among these three effects. The extrusions on silicon surface will be in embryo during the impact unloading stage and will grow up during the cluster rebounding stage. Furthermore, the critical impact velocity to induce the formation of extrusions on silicon surface is associated with the incidence angle of the cluster, while it is independent from the size of the cluster. The findings are instructive in optimizing the process parameters for ultraprecision machining of silicon wafer.

Section: A Impact Loading Stagementioning

confidence: 93%

Extrusion formation mechanism on silicon surface under the silica cluster impact studied by molecular dynamics simulation

Journal of Applied Physics

Guo

2008

Self Cite

“…[10][11][12][13][14] The simulations showed that c-Si would transform into Si-II during indentation loading or a locally ordered transient structure during impact loading and then transform into amorphous phase during unloading. And the phase transformation from Si-II or the locally ordered structure to amorphous phase is a reversible process.…”

Section: Introductionmentioning

confidence: 99%

“…And the phase transformation from Si-II or the locally ordered structure to amorphous phase is a reversible process. [10][11][12] Reference 13 showed the Si-III and Si-XII would be formed under indentation loading. Reference 14 studied the change in conductivity of silicon during indentation by MD simulation.…”

Section: Introductionmentioning

confidence: 99%

Dynamic phase transformation of crystalline silicon under the dry and wet impact studied by molecular dynamics simulation

Journal of Applied Physics

Guo

Lei

2010

Self Cite

Molecular dynamics simulation is applied in analyzing quantitatively the dynamic phase transformation of crystalline silicon under the dry and wet impact, respectively. At the impact loading stage, the phase transformation between fourfold silicon atoms and fivefold or threefold silicon atoms is affected only by the local pressure. The influence of the local temperature or the contact area on the phase transformation will emerge from the impact unloading stage. And the dynamic process of phase transformation between fourfold atoms and fivefold or threefold atoms will obey the Boltzmann distribution law by stages. The variance of the number of fivefold or fourfold atoms at impact loading stage is almost the same as the impact unloading stage. Furthermore, the dynamic residence time of fivefold or threefold atoms formed during the impact process will be about 250 fs. The half-life of these atoms is about 50 fs.

“…The fundamental mechanisms of the micro-wear of the CMP process are not well understood even though there are so many published papers about CMP modeling. In the light of Jiang's research [6,7] , there are four types of approaches for CMP models: the purely fluid mechanical approach, the fluid dynamics lubrication approach, the contact mechanics approach, and the viscous flow approach. Using the results of the CMP modeling research of the Massachusetts Institute of Technology (MIT), Cadence developed a CMP predictor that can be used for technology below 65 nm.…”

Section: Introductionmentioning

confidence: 99%

Effects of pattern characteristics on copper CMP

Ruan

et al. 2009

J. Semicond.

Copper chemical mechanical polishing (CMP) is influenced by geometric characteristics such as line width and pattern density, as well as by the more obvious parameters such as slurry chemistry, pad type, polishing pressure and rotational speed. Variations in the copper thickness across each die and across the wafer can impact the circuit performance and reduce the yield. In this paper, we propose a modeling method to simulate the polishing behavior as a function of layout pattern factors. Under the same process conditions, the pattern density, the line width and the line spacing have a strong influence on copper dishing, dielectric erosion and topography. The test results showed: the wider the copper line or the spacing, the higher the copper dishing; the higher the density, the higher the dielectric erosion; the dishing and erosion increase slowly as a function of increasing density and go into saturation when the density is more than 0.7.