ASCENT Theme 1(B) Update on Ferroelectric Modeling

Theme1B Update on Ferroelectric Modeling

Presenters: Andrew Kummel (UCSD): Key Experimental Results on HZO MIM and MIS from ASCENT and Beyond – 10 min

KJ Cho (UT Dallas): DFT models of Scaling Limits for HZO MIM and MIS Structures – 20 min

Kisung Chae (UCSD):  DFT Modeling for Strain Determination in Real Space TEM Imaging – 20 min

Abstract: DFT models have been constructed for MIM structures such as TiN-HZO-TiN with and without dielectric interlayers as well as MIS structures such as Si-HZO-TiN with and without dielectric interlayers. When no dielectric interlayers are present, there are no internal fields in the HZO in the MIM structures so the HZO can be aggressively scaled.  Conversely, when dielectric interlayers are present or in any MIS structure, scaling of either the HZO or the dielectric results in internal fields exceeding the breakdown voltages because the charge from the HZO cannot be properly compensated.  The high internal fields will facilitate defect formation which will limit endurance.  The results are consistent with the need to eliminate dielectric interlayers as seen in several results experimental studies.  Strain/tension play a large role in stabilizing the ferroelectric phase of HZO and related materials; using a novel method of finding the center of atoms in TEM images combined with DFT modeling, the strain/tension/sheer in individual grains can be measured.

DFT models have been constructed for MIM structures such as TiN-HZO-TiN with and without dielectric interlayers as well as MIS structures such as Si-HZO-TiN with and without dielectric interlayers. When no dielectric interlayers are present, there are no internal fields in the HZO in the MIM structures so the HZO can be aggressively scaled.  Conversely, when dielectric interlayers are present or in any MIS structure, scaling of either the HZO or the dielectric results in internal fields exceeding the breakdown voltages because the charge from the HZO cannot be properly compensated.  The high internal fields will facilitate defect formation which will limit endurance.  The results are consistent with the need to eliminate dielectric interlayers as seen in several results experimental studies.  Strain/tension play a large role in stabilizing the ferroelectric phase of HZO and related materials; using a novel method of finding the center of atoms in TEM images combined with DFT modeling, the strain/tension/sheer in individual grains can be measured.

This meeting is only available to the JUMP research community, such as Principal Investigators, Postdoc researchers, Students, and Industry/Government liaisons.