Along with a series of research works on the physical prototype and properties of the memory cell,an SPICE model for phase-change memory（PCM） simulations based on Verilog-A language is presented.By handling it with the heat distribution algorithm,threshold switching theory and the crystallization kinetic model,the proposed SPICE model can effectively reproduce the physical behaviors of the phase-change memory cell.In particular,it can emulate the cell＇s temperature curve and crystallinity profile during the programming process,which can enable us to clearly understand the PCM＇s working principle and program process.
It has been a challenge to fully understand the structural characteristics of laser-irradiation induced amorphous(L-a) Ge2Sb2Te5(GST) alloy due to the difficulties of collecting diffraction data from high purity specimens. In this paper,by fabricating GST thin films on different substrates,we exhibit an effective way of preparing L-a GST dots in submicron scale on various types of specially designed transmission electron microscope(TEM) grids. The structural characteristics of L-a GST in the form of pair distribution functions(PDF) can be achieved on single dots of L-a GST via selected area electron diffraction(SAED) . This general approach would be convenient for precisely producing laser-irradiation induced materials in submicron scale for structural investigation.
The effect of the ammonium molybdate concentration on the material removal rate（MRR） and surface quality in the preliminary chemical mechanical polishing（CMP） of a rough glass substrate was investigated using a silica-based slurry.Experimental results reveal that the ammonium molybdate concentration has a strong influence on the CMP behaviors of glass substrates.When the ammonium molybdate was added to the baseline slurry,polishing rates increased,and then decreased with a transition at 2 wt.%,and the root mean square（RMS） roughness decreased with increasing ammonium molybdate concentration up to 2 wt.%,after which it increased linearly up to 4 wt.%.The improvement in MRR and RMS roughness may be attributed to the complexation of hydrolysis products of the glass substrate with the ammonium molybdate so as to prevent their redeposition onto the substrate surface.It was found that there exists an optimal ammonium molybdate concentration at 2 wt.%for obtaining the highest MRR and the lowest RMS roughness within a particular polishing time.
