摘要:

The electrical properties of ultra thin dielectrics are highly important since they are a critical element of Metal-Oxide-Semiconductor Transistors (MOSTs) in ULSI technology. The determination of critical properties such as voltage-to-breakdown(VBD)and charge-to-breakdown(QBD)requires the use of either voltage or current stress measurements. It is known that if gate oxide thickness shrinks to approximately 5.5 nm the so-called soft or electrical breakdown may take place instead of hard or dielectric breakdown. In this paper soft breakdown (SBD) during Constant Voltage Stress (CVS) measurements is modelled using PSpice circuit simulator. The influence of elements such as oxide capacitance, tunnelling resistance, percolation path resistance, substrate resistance etc. is treated. The simulation results suggest that SBD characteristics are dependent not only on the physical processes in the oxide but also on the equivalent circuit used in the electrical test. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354381

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

A new metrology method has been developed for the monitoring of advanced gate dielectric processes associated with 0.1 &mgr;m technology. Unlike previous techniques that involved corona or Hg gate based methods, this technique measures all gate dielectric parameters on product as well as monitor wafers. This is accomplished with a specially designed small area elastic pressure probe contacting the gate oxide within the scribe lines of 200 or 300 mm wafers. The elastic probe method utilizes a semiconductor compatible material, which is specially conditioned to produce a nondamaging, highly repeatable contact. Extensive damage evaluations have been performed and indicate that no observable physical or electrical damage is introduced into the silicon by these pressure contacts. Critical parameters such as equivalent oxide thickness (EOT), threshold voltage, channel doping profile, oxide and interface trap charge, and leakage current can be determined with high precision and accuracy. For example, EOT repeatabilities of less than 0.3&percent; (one sigma) have been obtained. The technique is also highly useful for process development, especially in the area of ultra-thin gate oxides and advanced gate dielectrics. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354382

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

In this study, we performed HRTEM image simulations of a MOSFET device to determine the ability of HRTEM to detect gate oxide defects. The gate oxide was modeled as an amorphous silicon oxide 16.3 Å-thick, sandwiched between a gate and substrate. Both the gate and substrate were modeled as (100) silicon viewed along the [110] direction. Crystalline silicon defects were embedded in the model gate oxide and simulated images were calculated using a multi-slice approach with varying defect morphology, composition, size and orientation. Simulations predict that defects should be observable for very small specimen thickness (<100 Å) and large defect sizes (>40 Å), but not for specimen thickness and defect sizes typical of advanced CMOS devices analyzed in routine laboratory electron microscopy. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354383

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

In this study, we performed HRTEM image simulations of a MOSFET device to evaluate the accuracy of HRTEM in measuring gate oxide thickness. Gate oxide thickness measurements extracted from simulated images were compared to actual dimensions in the model structure to assess TEM accuracy. Results reveal no consistent trends in measurement accuracy as a function of specimen thickness, specimen tilt, or objective lens defocus. In general, thickness measurements performed with a conventional TEM could not be determined reliably with precision better than 10&percent;. However, thickness measurements could be made with no error using a spherical aberration corrected TEM. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354384

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We will describe a fundamental difference between the interpretation of optical and electrical measurements of gate dielectric thickness. This difference has major ramifications on the characterization of, and metrology for, advanced, alternate gate dielectrics and gate dielectric stacks. The purpose of this paper is to clear up possible misunderstandings that arise when comparing the thickness of gate dielectrics derived from optical and electrical measurements. Oxynitride data will be used to illustrate the divergence between optical and electrical measurements of thickness for films with a permittivity near and slightly above that ofSiO2.Experimental characterization ofTa2O5dielectrics will demonstrate the complementary nature of electrical and optical measurements. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354385

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We have examined a small group of tantalum pentoxide(Ta2O5)wafers with grazing incidence x-ray reflectivity (GIXR) and powder diffraction. GIXR gives accurate measurements of layer thickness, layer interface widths, and densities for single and multilayer samples. Powder diffraction allows detection of crystallinity, identification of specific phases or verification of amorphous structure. The combination of these two methods permits fairly detailed characterization of polycrystalline thin films. The densities obtained by GIXR vary over a considerable range from 5.08 g/cm3to 9.10 g/cm3. The theoretical densities for the hexagonal form and the orthorhombic form ofTa2O5are 8.316 g/cm3and 8.2 g/cm3respectively. The large variation in density suggests that other oxides may have formed or that other polymorphs ofTa2O5with lower densities may be present in some samples. The powder diffraction results indicate crystallinity in at least some of the samples. While this work has demonstrated good structural characterization, more useful conclusions await study of a well-structured sample matrix. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354386

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Silicon oxynitride blanket films approximately 2 nm in thickness were characterized in cross section using a 300 keV TEM/STEM. High resolution imaging was used to investigate the accuracy and precision of TEM film thickness measurements and their comparability to other techniques such as spectroscopic ellipsometry, secondary ion mass spectrometry, x-ray reflectivity, x-ray photoelectron spectroscopy, and medium energy ion scattering. Silicon oxynitride films were grown by SEMATECH and were characterized by several techniques in a SEMATECH-sponsored round robin. Cross sectional TEM samples were prepared by dimpling/ion milling and HRTEM micrographs were acquired at 297 keV using an imaging energy filter and a multiscan CCD camera. Thickness measurements were performed after calibrating the magnification using a phase contrast image of the silicon substrate. Approximately 10 measurements were performed for each film, including measurements on both sides of the cross section glue line and both sides of the dimple/ion mill perforation. Statistical analysis of the HRTEM thickness measurements reveals that the expanded uncertainty of the technique (with coverage factork=2,designed to estimate a 95&percent; confidence interval) can be larger than 0.33 nm. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354387

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Based on the bond-ionicity definition of Pauling, gate dielectric materials are grouped into three categories with increasing bond ionicity, continuous random networks, crn’s, modified crn’s with ionic components, mcrn’s, and random closed packed ionic structures, rcpis’s. Using this classification scheme, fully oxidizedTa2O5films prepared at low temperature, ∼300&hthinsp;°C, have mcrn’s, and are expected to have similar bonding arrangements and thermal stability to non-crystallineAl2O3andSiO2-rich, Zr silicate alloys. This is verified by combining previously published Raman data with more recent FTIR and EXAFS results. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354388

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

This paper identifies fundamental aspects of Si-dielectric and internal dielectric interfaces that limit the ultimate performance of Si field effect transistor, FET, devices for scaled complementary metal oxide semiconductor, CMOS, integrated circuits. Three different interface limitations are discussed: i) residual suboxide bonding atSi-SiO2interfaces, ii) bond induced mechanical strain atSi-Si3N4andSiO2-Si3N4interfaces, and iii) charged defects associated with heterovalent bonding at Si-high-k oxide and silicate dielectric interfaces. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354389

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

To achieve the future goals for logic device dielectric film thickness and composition metrology, a set of well-characterized calibration reference material standards are needed for validating real-time diagnostic techniques used during production. However, there are only a finite number of techniques capable of providing the desired information within this thickness range. Furthermore, the techniques available can disagree on the absolute measured film thickness by an amount that is greater than their respective measurement uncertainty. It is evident that more information is needed to establish a measurement technique capable of satisfying this requirement for the ULSI semiconductor manufacturing industry. A promising technique for characterizing ultrathin films is grazing incidence x-ray photoelectron spectroscopy (GIXPS). GIXPS utilizes the dependence on the material properties of the film, along with the incident angle of the x-rays to control the electric field penetration into the sample. By varying the angle of incidence from zero to some value slightly greater than the angle for total x-ray external reflection, it is possible to nondestructively probe the nature of the film depth profile. The desired physical properties, such as film profile, density and thickness, are extracted by constructing a model of the film structure and comparing the measured angle-dependent photoemission spectrum to the calculated spectrum. The measured dielectric thin film thickness and the film depth profile from a diverse group of silicon oxynitride samples in the range of 2 nm to 5 nm will be discussed. In addition, challenges associated with the dependence of the technique upon various fundamental materials parameters will be addressed. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1354390

出版商:AIP    

年代:1901

数据来源: AIP