Silicon doped hafnium oxide (HSO) and hafnium zirconium oxide (HZO) based FeFET: A material relation to device physics

Abstract

The recent discovery of ferroelectricity in thin film HfO2 materials renewed the interest in ferroelectric FET (FeFET) as an emerging nonvolatile memory providing a potential high speed and low power Flash alternative. Here, we report more insight into FeFET performance by integrating two types of ferroelectric (FE) materials and varying their properties. By varying the material type [HfO2 (HSO) versus hafnium zirconium oxide (HZO)], optimum content (Si doping/mixture ratio), and film thickness, a material relation to FeFET device physics is concluded. As for the material type, an improved FeFET performance is observed for HZO integration with memory window (MW) comparable to theoretical values. For different Si contents, the HSO based FeFET exhibited a MW trend with different stabilized phases. Similarly, the HZO FeFET shows MW dependence on the Hf:Zr mixture ratio. A maximized MW is obtained with cycle ratios of 16:1 (HfO2:Si) and 1:1 (Hf:Zr) as measured on HSO and HZO based FeFETs, respectively. The thickness variation shows a trend of increasing MW with the increased FE layer thickness confirming early theoretical predictions. The FeFET material aspects and stack physics are discussed with insight into the interplay factors, while optimum FE material parameters are outlined in relation to performance.

Area-Scalable 109-Cycle-High-Endurance FeFET of Strontium Bismuth Tantalate Using a Dummy-Gate Process

“…The gate stack of MFIS should be regarded as MFI(IL)S, as shown in in Figure 2a, where F, I, IL, S are connected in series. The IL is an interfacial layer between I and S which is formed during the ferroelectric crystallization annealing process of FeFETs [8,39,[55][56][57]. The main component of IL is silicon dioxide with an electric permittivity (ε IL ) of ε IL = 3.9.…”

Ferroelectric Field Effect Transistors Based on PZT and IGZO

“…CMOS compatible FeFET employing silicon (Si) transistors and Al doped HfO 2 as ferroelectric material were recently reported [3]- [5]. Ferroelectric gate thin film transistors (FeTFT) were developed using different ferroelectrics such as PZT [6]- [10], poly(vinylidene fluoridetrifluoroethylene) [P(VDF-TrFE)] [11]- [14], (Bi,La) 4 Ti 3 O 12 (BLT) [15] or HfO 2 -based materials (e.g., Si-doped or Zr-doped HfO 2 ) [16]- [19]. In terms of architecture, the [P(VDF-TrFE)] based FeTFT devices are generally top-gate, whilst the fully inorganic structures are bottom-gate.…”

“…Since the breakthrough of Böscke et al [20], which reported in 2011 the ferroelectricity of Si-doped HfO 2 , incremental focused researches have been performed in order to asses if HfO 2 based-materials can overcome some of the limitations of conventional ferroelectrics (such as PZT), markedly their (i) reduced compatibility with metaloxide-semiconductor (CMOS) technologies or (ii) limited scalability. The ferroelectricity of HfO 2 films manifests when the layer thickness is reduced to few nm (e.g., 10 nm) [16], [21]. However, this could generate an important technological hindrance, since a non-uniformity of only 1 nm will correspond to a thickness variation of 10%, with a negative impact on the overall performance reproducibility.…”

ToF-SIMS 3D Analysis of Thin Films Deposited in High Aspect Ratio Structures via Atomic Layer Deposition and Chemical Vapor Deposition

“…Various dopants influence the stabilization of the ferroelectric phase in hafnia thin films, for example, silicon (Si) [17,31,32], and such influence becomes more decisive in deep trench structures while the dopants concentration may change inside the HAR structure. Remarkably, it is more critical in low-doped materials, where such a low Si content is necessary, while a small deviation results in strong change in the stabilized phase [33]. As compared to planar film deposition, effects on the layer composition and crystal structure are expected to be different for HAR structures.…”