A three-dimensional finite element model for phase change random access memory is established to simulate electric, thermal and phase state distribution during （SET） operation. The model is applied to simulate the SET behaviors of the heater addition structure （HS） and the ring-type contact in the bottom electrode （RIB） structure. The simulation results indicate that the small bottom electrode contactor （BEC） is beneficial for heat efficiency and reliability in the HS cell, and the bottom electrode contactor with size Fx=80 nm is a good choice for the RIB cell. Also shown is that the appropriate SET pulse time is lOOns for the low power consumption and fast operation.
GONG Yue-Feng SONG Zhi-Tang LING Yun LIU Yan LI Yi-Jin
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.
