Effect of reactive magnetron sputtering parameters on structural and electrical properties of hafnium oxide thin films
Introduction
Ongoing development of the microelectronics, starting from the early 1960s of the 20th century, involves an increase in the integration degree of emerging semiconductor devices, as well as the increase of speed and functionality of integrated circuits (ICs). The scaling of complementary metal-oxide-semiconductor (CMOS) feature size has also caused a decrease of silicon dioxide (SiO2) gate oxide thickness into few nanometer regime. Semiconductor devices with such an ultra-thin SiO2 layer are characterized by unacceptably high leakage current resulting from tunneling current which leads to increased power consumption [1], [2]. In order to reduce the leakage current and capacitance of devices high-κ dielectric layers include HfO2, Al2O3TiO2, ZrO, CeO2 can be used as a substitution of ultra-thin silicon dioxide films [3]. From the point of view of applications in advanced microelectronic devices, hafnium oxide can be characterized by many important properties, such as: high dielectric constant (20–25), large band-gap (5.6 eV), amorphous or polycrystalline structure (depending on process temperature and fabrication method), compatibility with poly-silicon gate process, large conduction band offsets with Si and solid-sate thermodynamic stability on Si [3], [4], [5]. Hafnium oxide is one of the alternative dielectrics with high dielectric permittivity value that already has found applications in commercially available CMOS devices, i.e. as a gate dielectric in MOSFET devices [6], RRAM memories (Resistive Random Access Memory) [7] and for improvement of NVSM devices properties (Non-Volatile Semiconductor Memory) [8], [9]. Hafnium oxide is also used as a passivation layer in devices dedicated for special applications such as high temperature and high power electronics based on silicon carbide (SiC) [10], [11] or InGaAs/InP heterostructure bipolar transistors (HBT) [12]. HfOx is also one of the functional layers in gas sensors, in particular CO2 [13] or field-effect-transistor (FET) based sensors for the detection of deoxyribonucleic acid (DNA) hybridization [14]. Moreover, ISFET (Ion Selective Field Effect Transistors) sensor dedicated to pH, Na+, K, H+ is based on a silicon micromechanical transducers and in those application HfO2 acts as an sensitive layer [15]. HfOx is also an excellent layer from the point of view of applications as an antireflection coating. This is because of its superior properties such as thermal stability, relatively wide band-gap and transparent spectra range from the infrared to the ultraviolet [16]. The fabrication of HfOx films can be achieved using one of the well established for standard silicon-integrated-circuit deposition methods, i.e.: atomic layer deposition [9], reactive magnetron sputtering [17], plasma ion assisted deposition [18] or laser ablation [19]. Reactive magnetron sputtering is a low temperature deposition method which can be used for obtaining high quality thin films even on large area substrates. The method has also a number of other advantages including low cost manufacturing, capability for fabrication of thin oxide or nitride films from metallic target and easily controlled deposition process. In this work, the Taguchi design method was used to perform the series of technological experiments of hafnium oxide thin films deposition by means of reactive magnetron sputtering (RMS) method. Orthogonal experiment scheme (L934) [20] was designed and four critical parameters were taken into account: pressure in reactor chamber, sputtering power, oxygen partial pressure and deposition time. We also report on effects of post-deposition annealing on electrical characteristics of metal–insulator–semiconductor (MIS) structures with HfOx and HfOxNy gate dielectric and its structural properties.
Section snippets
Experimental
The hafnia films were deposited on 2-inch silicon 〈1 0 0〉 “p” substrates (1–10 Ω cm resistivity) cleaned just prior to the processing by Radio Corporation of America (RCA) method [21]. HfOx and HfOxNy thin films were fabricated in Plasmalab System 400 (Oxford Instruments Plasma Technology) at various process parameters: pressure in the reactor chamber, Ar and O2 flow rate, power applied to the reactive chamber and time (Table 1). Deposition temperature was 20 °C and argon flow was set at 25 ml/min.
Range analysis of sputtering parameters
The values of basic electro-physical properties evaluated from electrical characteristics (C–V, J–V) of studied MIS structures and ellipsometry measurements are presented in Table 2. Implementation of Taguchi's orthogonal arrays to optimize the RMS deposition of HfOx and to minimize the number of expensive technological experiments allowed us to achieve a number of trends of the influence of particular process parameter on various electro-physical properties of HfOx and MIS structures. In the
Conclusions
In this study the comparison of structural and electrical properties of magnetron sputtered hafnium dioxide and oxynitride thin films has been shown. A careful analysis of the influence of deposition process parameters (among them: pressure in the reactor chamber, Ar and O2 flow rates, power applied to the reactor chamber and deposition time) on properties of HfOx layers has been also performed. Presented results have shown that in the case of HfOx as well as HfOxNy gate dielectric, the most
References (28)
Chemical structure and electrical properties of sputtered HfO2 films on Si substrates annealed by rapid thermal annealing
Vacuum
(2009)Structure and optical properties of HfO2 thin films on silicon after rapid thermal annealing
Opt. Mater.
(2010)- et al.
On the scaling issues and high-k replacement of ultrathin gate dielectrics for nanoscale MOS transistors
Microelectron. Eng.
(2006) - et al.
Application of deposited by ALD HfO2 and Al2O3 layers in double-gate dielectric stacks for non-volatile semiconductor memory (NVSM) devices
Appl. Surf. Sci.
(2012) - et al.
Surface photovoltage and Auger electron spectromicroscopy studies of HfO2/SiO2/4H-SiC and HfO2/Al2O3/4H-SiC structures
Appl. Surf. Sci.
(2012) - et al.
Amorphous hafnium oxide thin films for antireflection optical coatings
Surf. Coat. Technol.
(2008) Influence of O2/Ar flow ratio on the structure and optical properties of sputtered hafnium dioxide thin films
Surf. Coat. Technol.
(2010)- et al.
Development of hafnium based high-k materials—a review
Mater. Sci. Eng. R
(2011) - et al.
A technical formula for determining the insulator capacitance in a MOS structure
Solid-State Electron.
(1992) - et al.
Structural and electrical characteristics of RF-sputtered HfO2 high-k based MOS capacitors
Solid-State Electron.
(2011)
Effect of the post-deposition annealing on electrical characteristics of MIS structures with HfO2/SiO2 gate dielectric stacks
Mater. Sci. Eng. B-Solid
Study of the effect of thermal annealing on high k hafnium oxide thin film structure and electrical properties of MOS and MIM devices
J. Mater. Sci. Mater. Electron.
Reliability issues of double gate dielectric stacks based of hafnium dioxide (HfO2) for applications in non-volatile semiconductor memory (NVSM) devices
Microelectron. Reliab.
Advancement of MOSFET with the application of hafnium
Cited by (24)
Technology and optimization of hafnium oxynitride (HfO<inf>x</inf>N<inf>y</inf>) thin-films formed by pulsed-DC reactive magnetron sputtering for MIS devices
2020, Microelectronic EngineeringCitation Excerpt :By the analysis of the results shown in Fig. 2, it can be assumed that the annealing at 300 °C results in the improvement of electrical parameters of fabricated hafnium oxynitride films. Similar results were obtained in our previous work, which was concentrated on hafnium oxide (HfOx) layers [32]. In all cases presented in Fig. 2, the annealed material can be characterized by reasonably lower effective charge density and higher relative permittivity, as compared to as-deposited films.
Electrical and chemical characterizations of hafnium (IV) oxide films for biological lab-on-a-chip devices
2018, Thin Solid FilmsCitation Excerpt :While leakage current is desired in some LOC applications, aqueous electrolyte solutions required for many biological applications can cause alkali ion contamination in the SiO2 leading to undesirable device instability [20]. Common SiO2 replacements include HfO2, Si3N4, La2O3, Al2O3, ZrO2, TiO2, HfSiO, CeO2, and LaAlO3 [19–21]. Dielectric constants for these materials range from 3.9 for SiO2 to 80 for TiO2; the material explored here, HfO2, is 20–25 [22].
Control of interfacial layer growth during deposition of high-κ oxide thin films in reactive RF-sputtering system
2017, Applied Surface ScienceCorrosion behavior of hafnium in anhydrous isopropanol and acetonitrile solutions containing bromide ions
2017, Transactions of Nonferrous Metals Society of China (English Edition)