Correlation between the macroscopic ferroelectric material properties of Si:HfO2 and the statistics of 28 nm FeFET memory arrays. Issue 1 (20th June 2016)

• Record Type: Journal Article
• Authors: Mueller, S.; Slesazeck, S.; Henker, S.; Flachowsky, S.; Polakowski, P.; Paul, J.; Smith, E.; Müller, J.; Mikolajick, T.
• Is Part Of: Ferroelectrics. Volume 497:Issue 1(2016)
• Page Start: 42
• Page End: 51
• Publication Date: 2016-06-20
• Subjects: FeFET -- Si:HfO2 -- FE-HfO2 -- FRAM -- hafnium oxide; Ferroelectricity -- Periodicals; Ferroelectric crystals -- Periodicals; 537
• DOI: 10.1080/00150193.2016.1162021
• Languages: English
• ISSNs: 0015-0193

Abstract

ABSTRACT: With the discovery of ferroelectric hafnium oxide (FE-HfO2 ), the ferroelectric field effect transistor (FeFET), a long-term contender for non-volatile data storage, has finally managed to scale to the 2× nm technology node. Here for the first time, we correlate the thickness dependent ferroelectric properties of Si:HfO2 with the memory characteristics of small (56 bit) FeFET arrays. First, an electrical and structural analysis of metal-ferroelectric-metal capacitors is given. Even though possessing room-temperature deposited top electrodes, TiN / Si:HfO2 (20 nm) / TiN capacitors are showing deteriorated polarization characteristics as compared to their 10 nm Si:HfO2 counterparts. This could be attributed to an increased monoclinic phase fraction, as indicated by small-signal capacitance voltage and grazing incidence X-ray diffraction measurements. Identical Si:HfO2 thin films with thicknesses of 10 nm and 20 nm respectively, were utilized in a 28 nm high-k metal-gate CMOS flow to form small FeFET memory arrays of AND architecture. After extracting the most suitable operating conditions from erase matrix, single cell evaluation was performed by standard VP /3 program and a novel VP /3 positive-source drain erase scheme. Array cells incorporating 10 nm Si:HfO2 films showed a maximum memory window of 1.03 V whereas cells incorporating 20 nm Si:HfO2 films could reach up to 1.57 V. Moreover, in accordance to the basic material properties, the previously observed increased monoclinic phase fraction in 20 nm Si:HfO2 thin films correlate well with a reduced number of functional FeFET cells.