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The study presents the effects of nitrogen incorporated into hafnium silicate and the comparisons of several nitridation methods and processes.

Ferroelectric random access memory (FeRAM) is an attractive candidate technology for embedded nonvolatile memory, especially in applications where low power and high program speed are important. Market introduction of high-density FeRAM is, however, lagging behind standard complementary metal-oxide semiconductor (CMOS) because of the difficult integration technology. This paper discusses the major integration issues for high-density FeRAM, based on SrBi2Ta2O9 (strontium bismuth tantalate or SBT), in relation to the fabrication of our stacked cell structure. We have worked in the previous years on the development of SBT-FeRAM integration technology, based on a so-called pseudo-three-dimensional (3D) cell, with a capacitor that can be scaled from quasi two-dimensional towards a true three-dimensional capacitor where the sidewalls will importantly contribute to the signal. In the first phase of our integration development, we integrated our FeRAM cell in a 0.35 μm CMOS technology. In a second phase, then, possibility of scaling of our cell is demonstrated in 0.18 μm technology. The excellent electrical and reliability properties of the small integrated ferroelectric capacitors prove the feasibility of the technology, while the verification of the potential 3D effect confirms the basic scaling potential of our concept beyond that of the single-mask capacitor. The paper outlines the different material and technological challenges, and working solutions are demonstrated. While some issues are specific to our own cell, many are applicable to different stacked FeRAM cell concepts, or will become more general concerns when more developments are moving into 3D structures. [ABSTRACT FROM AUTHOR]

Different aspects of the integration of strontium bismuth tantalate (SBT)-based high-density ferroelectric random access memory (FeRAM) is discussed in relation to the fabrication of pseudo-three-dimensional (3D) cell structure. The excellent electrical and reliability properties of the small integrated FeCAP prove the feasibility of the technology, while the verification of the potential electrical 3D effect confirms the basic scaling potential of the concept beyond that of the single-mask capacitor.

Abstract: In this work we present an evaluation and understanding of corona charge measurements on decoupled plasma nitrided (DPN) HfSiOx. Typical corona charge parameters such as equivalent oxide thickness (EOT), density of interface states (D it) and saturated surface voltage (V sat) are evaluated. It is shown that especially D it and V sat are promising parameters for nitiridation monitoring as they show correlation to DPN parameters within good accuracy. Fundamental explanation is given for the observed behaviour of V sat by use of a direct tunneling model. [Copyright &y& Elsevier]

An instrumental method is proposed for the quantitative evaluation of cell/particle adhesion at solid/liquid interfaces. As a measure of adhesion, the retardation of convective transport in capillary flow tubes is determined. The flow tubes, for such purposes, have been internally coated with the substance under investigation. AC-operated electronic gating is applied, preferentially, for the determination of the elution rate. This technique, to some extent, is similar to that of high-pressure liquid chromatography (HPLC). However, the transport mechanism is different as in this case, where transport mainly takes place about halfway between the capillary axis and the wall (Segré-Silberberg effect). At specific flow rates of the carrier liquid, cells/particles repeatedly contact the wall, only to be released again as a consequence of increasing lift and drag. This phenomenon depends on the chemical nature of the capillary wall coating and causes measurable retardation of transport. A transport model is proposed that predicts flow conditions under which transport retardation and adhesive interaction are to be expected. Experiments prove that the Segré-Silberberg effect, i.e., the occurrence of a preferential pathway of transport, is fully established already at capillary lengths of a few decimeters, and that the occurring retardation of transport, if any, is governed by the chemical nature of the capillary wall coatings. The area ens closed between the cumulative elution curves of sample and reference materials offers a reproducible measure of adhesion. The technique is fast, sensitive, and reliable. [ABSTRACT FROM AUTHOR]

This paper reports on the integration of MOCVD SBT based stacked ferroelectric capacitors in a 0.35 μm CMOS technology for embedded FeRAM, using a ferroelectric capacitor (FeCap) that is scalable to a 3D configuration. The electrical parameters of the CMOS devices with and without FeCap integration are presented. No significant shifts of the CMOS characteristics are noticed after FeCap integration. Also the effects of the CMOS processing on the FeCaps are discussed. There is no degradation of the hysteresis loops of the FeCaps throughout the CMOS back-end-of-line processing, which proves that the integrated encapsulation layer effectively prevents any hydrogen induced damage. Another key element in the successful integration of stacked ferroelectric devices is the conductive oxygen barrier, which protects the plugs from oxidation. A low contact resistance and a high yield are obtained on plug contacts covered by the oxygen barrier. Also damage free etching is a critical issue in FeRAM integration. Excellent results are presented for the etch process to form the contacts to the electrodes. [ABSTRACT FROM AUTHOR]

A method is described to determine the mobility of inversion charge carriers on Si substrates with SiO2 and HfO2 gate dielectrics. It is a completely contactless method combining corona charge and charge spreading metrology. [Patent Application Nos. EP 07118673 and U.S. 60940594.] It is shown that from such measurements mobility of inversion charge carriers can be calculated as a function of the effective electric field. The resulting mobility curves are comparable to those found in transistors. [ABSTRACT FROM AUTHOR]