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The palladium nanocrystals self-organized growth and its charge storage effect

Author: HuangWanYi
Tutor: DingShiJin
School: Fudan University
Course: Microelectronics and Solid State Electronics
Keywords: Non - volatile memory Separate charge storage Magnetron sputtering Rapid thermal annealing Palladium nanocrystals
CLC: O614.823
Type: Master's thesis
Year: 2011
Downloads: 38
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Abstract

With the continuous development of semiconductor technology, more and more high integration density non-volatile flash memory, storage units feature size is decreasing, thus traditional polysilicon floating gate flash memory is facing serious challenges, such as tunneling thinning of the oxide layer causes the degradation of data retention capability. Based on the separation of the charge stored in non-volatile memory, thinner tunneling oxide layer while maintaining good data retention characteristics, which can bring lower programming / erasing voltage and faster programming / erasing speed, is one of the next-generation flash memory ideal solution. Based on this idea, this paper studies the the metallic Pd Nanocrystals method as well as the electrical properties of the charge storage center study. Specifically includes the following aspects: (1) using the method of the metal thin film, and after deposition of the magnetron sputtering rapid thermal annealing (RTA), palladium (Pd) grown on A1203 dielectric film Nanocrystals process. Firstly, the factors that affect the deposition rate of the palladium membrane, experimental studies to find a more satisfactory deposition rate. Subsequently, a more systematic study of the effects of annealing temperature and annealing time, RTA heating rate of growth of palladium nanocrystals. The results showed that the initial magnetron sputtering target power is 10W, an Ar gas flow of 45 sccm, the deposition conditions of the deposition time is 230s, the obtained film is more conducive to the growth of the nano-crystalline. Further, in the process of the RTA form palladium Nanocrystals, as the annealing temperature increases, the size of the palladium Nanocrystals becomes large, density decreases. Through process optimization, it is found that the ideal conditions of the RTA annealing temperature of 850 ° C annealing time of 15s, a heating rate of 20 ° C / s. Under this condition, the palladium Nanocrystals obtained an average diameter of 10nm, a density of 4 x 1011cm-2. This paper also, on the other hand, the study of the growth characteristics of the conventional SiO2 dielectric palladium on Nanocrystalline revealed in the sputtering power is 10W, an Ar gas flow of 45 sccm, the deposition conditions of the deposition time is 400s, and annealing temperature RTA under conditions of 750 ℃, the annealing time is 15s and a heating rate of 20 ° C / s, to obtain a mean diameter of 12nm, a density of 1.5 × 1011cm-2 of the palladium nanocrystalline. (2) by reactive co-sputtering annealing prepared Pd nanocrystals embedded in TiO2 high dielectric constant (High-k) dielectric films. First, by O2 and Ar mixed plasma environment of sputtering metal Pd and the Ti target to obtain PdTiO dielectric film The composite film was then after high temperature rapid thermal anneal in N2 atmosphere, thereby forming embedded Pd nanocrystalline TiO2 film. By means of X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analysis means, a systematic study of the different Pd / Ti sputtering power, different RTA conditions on Pd nanocrystals Characteristics of the forming process, the chemical composition and the material structure. The results showed that the relative TiPdO film Pd content is higher, the greater the annealing after the formation of Pd nanocrystalline particles. Moreover, with the rapid thermal annealing temperature, Pd nanocrystalline particles gradually becomes large. XPS data analysis showed that the initial film cosputtering PdTiO containing PdO2, the PdO, TiO2, Ti2O3 ingredients; after 600 ° C rapid thermal annealing, PdO2 completely decomposed, PdO partially decomposed, accompanied Ti2O3 to TiO2 The occurrence of the transformation processes. When the rapid thermal annealing temperature was increased to 900 ° C, PdO continued decomposition occurs, and the larger diameter of Pd nanoparticles. (3) Production of atomic layer deposition A1203 tunneling layer and barrier layer embedded Pd nanocrystalline Ti02 film as charge trapping layer MOS capacitor structure, and Pd metal electrode. The electrical test results show that the CV hysteresis window of the MOS structure is increasing with increasing the range of the scanning voltage, indicating that the embedded Pd nanocrystalline TiO2 film having a good charge trapping characteristics. When the scan range of ± 3V for Pd nanocrystals embedded MOS capacitor, the capacitor showed CV hysteresis the window (AVFB)-0.5V. Increasing with the increase of the scanning voltage hysteresis window. When the the scan voltage range of 9V, CV hysteresis window reached (ΔVFB) 8.2V. Interestingly, when scanning voltage range from ± 3V to ± 5V, the flat-band voltage offset mutation from 0.5V to 3.1V. Moreover, when the forward scan, with the increase of the voltage of the initial scan, the flat band voltage VFB of the MOS capacitor, a significant move to the negative voltage direction, and there is no saturation phenomenon appears. However, for negative scanning, with the initial scan voltage (positive bias) increases, and the resulting flat band voltage is shifted to the positive direction, but soon reach saturation. In other words, when the initial scan voltage ≤ 7V, the flat-band voltage VFB obtained with the increase in the voltage of the initial scan offset the obvious positive direction. However, when the initial scan voltage ≥ 9V, flat-band voltage VFB obtained basic positive direction again with increasing initial scan voltage offset electronic storage reached saturation. This is due to the charge tunneling mechanism under low pressure main is direct tunneling, as compared FN tunneling under high pressure; For the hole is concerned, since the valence band offset of metal Pd and the blocking layer medium (band offset) than large, so that the hole under high pressure is also unlikely to occur FN tunneling, while still mainly to the direct tunneling. Meanwhile, the experimental results show that when the constant voltage of 9V, the applied pulse width of 10ns can make the flat band voltage of the MOS capacitor to generate-2V offset;, the pulse voltage to 7V when the applied pulse width is constant 10ms will be able to make the MOS The flat-band voltage shift of the capacitance of-2V. By the calculation of the effective injection of charge density and the injection speed for different pulse voltage and pulse width, by calculating the maximum injection charge density of about 8 x 1011cm-2. The same time, the charge injection process substantially occurs at the initial stage, and the effective charge injection speed the initial 10ns within about 6 x 1012cm-2μs-1. Experiments show that the the nanocrystal memory of this structure will be great.

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CLC: > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Metal elements and their compounds > First Ⅷ group metal elements and their compounds > Platinum group metal element > Palladium Pa
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