An overview of the state of art in ferroelectric thin films is presented. First, we review applications: microsystems' applications, applications in high frequency electronics, and memories based on ferroelectric materials. The second section deals with materials, structure (domains, in particular), and size effects. Properties of thin films that are important for applications are then addressed: polarization reversal and properties related to the reliability of ferroelectric memories, piezoelectric nonlinearity of ferroelectric films which is relevant to microsystems' applications, and permittivity and loss in ferroelectric films-important in all applications and essential in high frequency devices. In the context of properties we also discuss nanoscale probing of ferroelectrics. Finally, we comment on two important emerging topics: multiferroic materials and ferroelectric one-dimensional nanostructures. (c) 2006 American Institute of Physics.

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Ferroelectric thin films: Review of materials, properties, and applications

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

The silicon-based microelectronics industry is rapidly approaching a point where device fabrication can no longer be simply scaled to progressively smaller sizes. Technological decisions must now be made that will substantially alter the directions along which silicon devices continue to develop. One such challenge is the need for higher permittivity dielectrics to replace silicon dioxide, the properties of which have hitherto been instrumental to the industry's success. Considerable efforts have already been made to develop replacement dielectrics for dynamic random-access memories. These developments serve to illustrate the magnitude of the now urgent problem of identifying alternatives to silicon dioxide for the gate dielectric in logic devices, such as the ubiquitous field-effect transistor.

Alternative dielectrics to silicon dioxide for memory and logic devices

Imagine you are in the last stages of typing your thesis, the year is 1980, and it's a hot, hazy summer afternoon, a thunderstorm brews on the horizon. Tense and tired, you have forgotten to save the document on your hard disk. Suddenly, lightning strikes! Your computer shuts down. Your final chapter is lost.

The Physics of Ferroelectric Memories

A transistor having a gate electrode, a source electrode, a drain electrode, a dielectric material and a channel region disposed between the source electrode and drain electrode. The channel region includes a portion doped with an impurity to change the fixed charge density within the portion relative to a remainder of the channel region.

Transistor including a deposited channel region having a doped portion

A via etch to contact a capacitor with ferroelectric between electrodes together with dielectric on an insulating diffusion barrier includes two-step etch with F-based dielectric etch and Cl- and F-based barrier etch.

Integrated circuit and method

An embodiment of the instant invention is a ferroelectric capacitor formed over a semiconductor substrate, the ferroelectric capacitor comprising: a bottom electrode formed over the semiconductor substrate, the bottom electrode comprised of a bottom electrode material (304 of FIG. 4 a); a top electrode formed over the bottom electrode and comprised of a first electrode material (306 and 308 of FIG. 4a); a ferroelectric material (306 of FIG. 4 a) situated between the top electrode and the bottom electrode; and a hardmask formed on the top electrode and comprising a bottom hardmask layer (402 of FIG. 4 a) and a top hardmask layer (408 of FIG. 4 a) formed on the bottom hardmask layer, the top hardmask layer able to with stand etchants used to etch the bottom electrode, the top electrode, and the ferroelectric material to leave the bottom hardmask layer substantially unremoved during the etch and the bottom hardmask layer being comprised of a conductive material which substantially acts as a hydrogen diffusion barrier.

Hardmask designs for dry etching FeRAM capacitor stacks

An important application of ferroelectric films is their incorporation into dynamic random-access memories (DRAMs) as the storage node capacitor dielectric. Dynamic random-access memories represent a large market that is experiencing strong growth, but they are particularly significant as the technology leader for semiconductor devices. As products move to higher and higher integration density, new developments are first introduced in DRAMs. The steady trend toward higher density has placed severe demands on the device designs, particularly with respect to “squeezing” the capacitor into the available space.

High-Permittivity Perovskite Thin Films for Dynamic Random-Access Memories

Ferroelectricity in HfO2-based materials, especially Hf0.5Zr0.5O2 (HZO), is today one of the most attractive topics because of its wide range of applications in ferroelectric random-access memory, ferroelectric field-effect transistors, ferroelectric tunneling junctions, steep-slope devices, and synaptic devices. The main reason for this increasing interest is that, when compared with conventional ferroelectric materials, HZO is compatible with complementary metal–oxide–semiconductor flow [even back-end of the line thermal budget] and can exhibit robust ferroelectricity even at extremely thin (< 10 nm) thicknesses. In this report, recent advances in the ferroelectric properties of HZO thin films since the first report in 2011, including doping effects, mechanical stress effects, interface effects, and ferroelectric film thickness effects, are comprehensively reviewed.

Ferroelectric Hf 0.5 Zr 0.5 O 2 Thin Films: A Review of Recent Advances

A preferred embodiment of this invention comprises an oxidizable layer (e.g. TiN 50), a conductive exotic-nitride barrier layer (e.g. Ti-Al-N 34) overlying the oxidizable layer, an oxygen stable layer (e.g. platinum 36) overlying the exotic-nitride layer, and a high-dielectric-constant material layer (e.g. barium strontium titanate 38) overlying the oxygen stable layer. The exotic-nitride barrier layer substantially inhibits diffusion of oxygen to the oxidizable layer, thus minimizing deleterious oxidation of the oxidizable layer.

Scott R. Summerfelt

Papers

Integrated circuit and method

Hardmask designs for dry etching FeRAM capacitor stacks

High-Permittivity Perovskite Thin Films for Dynamic Random-Access Memories

Ferroelectric Hf 0.5 Zr 0.5 O 2 Thin Films: A Review of Recent Advances

A conductive amorphous-nitride barrier layer for high dielectric-constant material electrodes