Challenges for plasma etch integration of ferroelectric capacitors in FeRAM's and DRAM's

Abstract

The plasma etch process requirements are different for etching 2μm ferroelectric capacitor structures in FeRAM's (SRAM) vs. the smaller capacitor sizes (0.2–0.5 μm) of DRAM's. Plasma etch integration of ferroelectric capacitors presents three major differences between FeRAM's and DRAM's. The first difference is in the ferroelectric capacitor structure. FeRAM's use planar capacitors with top side metal contacts to vias while DRAM's use vertical capacitor structures with bottom side contact to a poly post structure. The second major difference is in material selected and thickness of layers. FeRAM's use thicker electrodes of Pt or Ir and a thicker PZT or Y1 dielectric layer. FeRAM's use a thick bottom electrode (and a thin top electrode) consisting of Pt, Ru or Ir and a thin BST dielectric layer. The third major difference is the plasma etch process requirements for the two devices. FeRAM's require a clean etch process and no corrosion. Profile is not critical but should be maintained at greater than 60° for 2μm bottom post electrode. An HRe^? (Highly Density Reflected Electron) etch system is used to develop process trends for ferroelectric capacitor applications.     

美国CDE公司表面安装(SMT)电容及其应用选型

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并联电容器装置保护用氧化锌避雷器的选型问题

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GFD—360型涂层钢板焊接设备及工艺的开发

本文介绍了本课题组研制、开发成功的GFD－360型涂层钢板，专用点焊机的机械部分、主回路电气、微机控制等原理及其焊接工艺规范。     

阳极铝箔交流腐蚀发孔对比容的影响

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Development of Ferroelectric Ceramics with High Dielectric Constant and Low Dissipation Factor for High-Voltage Capacitors

Both ferroelectric BaTiO₃-based and SrTiO₃-based dielectric ceramics with high dielectric constant and low dissipation factor have been successfully developed, and applied into mass production for high-voltage ceramic capacitors. Crystalline phases of the ceramics were identified by XRD. STEM study of the ceramics was also conducted. Based on the computer simulation of a shell-core and two-phase mixed structural model proposed, a novel processing method was employed to produce SrTiO₃-based ceramics with the following satisfactory dielectric properties: dielectric constant at room temperature _20C=2000, dissipation factor at room temperature D _20C=0.003, temperature coefficient of dielectric constant = –8% (–25°C to 85°C), and, breakdown electric field E _b=10kV/mm(dc). Optional composition of BaTiO₃-based ceramics has been obtained through the orthogonal design experimentation: BaTiO₃-xBaZrO₃-yBaSnO₃, where x = 8wt% and y = 6wt%, with minor additions of MnSiO₃, WO₃, CeO₂, Bi₂(SnO₃)₃ and ZnO. Its major properties are as follows: Curie temperature T _c = 21°C, _20C=18,000, D _20'C = 0.008, =–80% (–25°C+85°C) and E _b = 8kV/mm (dc).     

High pass filter with above IC integrated SrTiO3 high K MIM capacitors

This paper describes realization and characterization of SrTiO₃ (STO) high K MIM capacitors above BiCMOS integrated circuit (IC). These capacitances are connected to IC and are used as coupling capacitors in order to realize a high pass filter. Surface capacitance achieved is 10 nF/mm² with capacitance value of 1.2 nF. The process for STO MIM fabrication does not exceed 400 °C, which is compatible with interconnections. Typical K and dielectric losses values obtained are, respectively 110% and 2%. Yield obtained reaches 83% for capacitors. A functional high pass filter using these STO capacitors was realized in this study. It exhibits a cut-off frequency at 6.5 kHz and a constant gain at higher frequencies of −1.3 dB.     

并网风电机组补偿电容器投入过程研究

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Characterization of ferroresonant modes in HV substation with CB grading capacitors

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Matching ratio between positive and negative electrodes for double-layer capacitors

For double-layer capacitors in alkaline electrolyte, the specific capacitance of the positive electrode is not equal to that of the negative one. Thus, capacitor performance cannot be optimal with a positive/negative electrode matching ratio of 1. In this study nanoporous glassy carbons (NPGCs) were employed as the electrodes of capacitors, and the influence of matching ratio between positive and negative electrode on capacitor performance was systematically investigated. In aqueous KOH, the specific capacitance of the positive electrode is lower than that of the negative electrode. The matching ratio at which a maximum capacitance is obtained is dependent on the values of the positive and negative electrode capacitance. At low current rate, the highest specific capacitance is achieved at a matching ratio slightly higher than 1. At high current rate, a capacitor has the highest specific capacitance with the lowest resistance at a matching ratio of 1.5. This indicates that an optimum matching relationship between positive and negative electrodes is attained.