Browsing by Author "Kim, Si Joon"
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Item Effect of Film Thickness on the Ferroelectric and Dielectric Properties of Low-Temperature (400 ⁰C) Hf₀.₅Zr₀.₅O₂ Films(American Institute of Physics) Kim, Si Joon; Mohan. Jaidah; Lee, Jaebeom; Lee, Joy S.; Lucero, Antonion T.; Young, Chandwin D.; Colombo, Luigi; Summerfelt, Scott R.; San, Tamer; Kim, Jiyoung; Kim, Si Joon; Mohan. Jaidah; Lee, Jaebeom; Lee, Joy S.; Lucero, Antonion T.; Young, Chandwin D.; Colombo, Luigi; Kim, JiyoungWe report on the effect of the Hf₀.₅Zr₀.₅O₂ (HZO) film thickness on the ferroelectric and dielectric properties using pulse write/read measurements. HZO films of thicknesses ranging from 5 to 20 nm were annealed at 400 ⁰C for 1min in a nitrogen ambient to be compatible with the back-end of the line thermal budget. As the HZO film thickness decreases, low-voltage operation (1.0V or less) can be achieved without the dead layer effect, although switching polarization (P_{sw}) tends to decrease due to the smaller grain size. Meanwhile, for 20-nm-thick HZO films prepared under the identical stress (similar TiN top electrode thickness and thermal budget), the P_{sw} and dielectric constant are reduced because of additional monoclinic phase formation.Item Ferroelectric Hf₀․₅Zr₀․₅O₂ Thin Films: A Review of Recent Advances(Springer, 2018-09-28) Kim, Si Joon; Mohan, Jaidah; Summerfelt, Scott R.; Kim, Jiyoung; 0000-0003-2781-5149 (Kim, J); 70133685 (Kim, J); Mohan, Jaidah; Kim, JiyoungFerroelectricity 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 (<10nm) 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.Item Ferroelectric TiN/Hf₀.₅Zr₀.₅O₂/Tin Capacitors with Low-Voltage Operation and High Reliability for Next-Generation FRAM Applications(Institute of Electrical and Electronics Engineers Inc.) Kim, Si Joon; Mohan, Jaidah; Young, Chadwin D.; Colombo, Luigi; Kim, Jiyoung; Summerfelt, S. R.; San, T.; 0000-0003-0690-7423 (Young, CD); 0000-0003-2781-5149 (Kim, J); 70133685 (Kim, J); Kim, Si Joon; Mohan, Jaidah; Young, Chadwin D.; Colombo, Luigi; Kim, JiyoungIn this study, we investigated the ferroelectric properties of Hf₀.₅Zr₀.₅O₂ (HZO) thin films with different thicknesses (5-20 nm) deposited by atomic layer deposition for the development of future ferroelectric random access memory cells. HZO-based capacitors with a thickness of 5 nm exhibited a switching polarization of ~13 μC/cm² and a ferroelectric saturation voltage of 1.0 V as extracted from the pulse write/read measurements. Furthermore, we performed fatigue measurements and we found no degradation up to 10¹⁰ switching cycles at 1.2 V.Item Large Ferroelectric Polarization of TiN/Hf₀․₅Zr₀․₅0₂ Capacitors Due to Stress-Induced Crystallization at Low Thermal Budget(Amer Inst Physics, 2018-10-22) Kim, Si Joon; Narayan, Dushyant; Lee, Jae-Gil; Mohan, Jaidah; Lee, Joy S.; Lee, Jaebeom; Kim, Harrison S.; Byun, Young-Chul; Lucero, Antonio T.; Young, Chadwin D.; Summerfelt, Scott R.; San, Tamer; Colombo, Luigi; Kim, Jiyoung; 0000-0001-7335-1053 (Lee, JS); 0000-0001-9477-5728 (Byun, Y-C); 0000-0003-0690-7423 (Young, CD); 0000-0003-2781-5149 (Kim, J); 70133685 (Kim, J); Kim, Si Joon; Narayan, Dushyant; Lee, Jae-Gil; Mohan, Jaidah; Lee, Joy S.; Lee, Jaebeom; Kim, Harrison S.; Byun, Young-Chul; Lucero, Antonio T.; Young, Chadwin D.; Kim, JiyoungWe report on atomic layer deposited Hf₀․₅Zr₀․₅0₂ (HZO)-based capacitors which exhibit excellent ferroelectric (FE) characteristics featuring a large switching polarization (45 μC/cm²) and a low FE saturation voltage (~1.5V) as extracted from pulse write/read measurements. The large FE polarization in HZO is achieved by the formation of a non-centrosymmetric orthorhombic phase, which is enabled by the TiN top electrode (TE) having a thickness of at least 90nm. The TiN films are deposited at room temperature and annealed at 400 ⁰C in an inert environment for at least 1 min in a rapid thermal annealing system. The room-temperature deposited TiN TE acts as a tensile stressor on the HZO film during the annealing process. The stress-inducing TiN TE is shown to inhibit the formation of the monoclinic phase during HZO crystallization, forming an orthorhombic phase that generates a large FE polarization, even at low process temperatures.