Matthew Wormington - Academia.edu (original) (raw)
Papers by Matthew Wormington
Acta Crystallographica Section A Foundations of Crystallography, 1996
Physica B: Condensed Matter, 1998
Grazing incidence diffuse X-ray scattering data from a Co-Cu multilayer with stepped interfaces g... more Grazing incidence diffuse X-ray scattering data from a Co-Cu multilayer with stepped interfaces grown by molecular beam epitaxy on a copper silicide buffer on a silicon substrate has been analysed using a computer code based on a fractal interface within the distorted wave Born approximation. We have extended the theory to include the scattering from a stepped interface and have shown that a single set of structural parameters can be used to obtain an excellent agreement between simulation and experimental data taken under very different X-ray optical conditions. The symmetry of the diffuse scatter on rotation about the surface normal can be explained if it arises from step bunching at the ends of extensive flat terraces. These steps have a self-affine nature, enabling the fractal model to be used successfully. 1998 Elsevier Science B.V. All rights reserved.
Journal of Non-Crystalline Solids, 1999
ABSTRACT
Metrology, Inspection, and Process Control XXXVII
Journal of micro/nanopatterning, materials, and metrology, Mar 22, 2023
MRS Proceedings, 1994
ABSTRACTGrazing incidence X-ray reflectivity may be used to measure surface topography including ... more ABSTRACTGrazing incidence X-ray reflectivity may be used to measure surface topography including roughness and correlation lengths to sub-nanometre precision. A study is made of a technically important surface, a carefully-polished specimen of Zerodur glass-ceramic, which has been measured by diffuse scatter of CuKα X-radiation and atomic-force profilometry methods. The data have been analysed in terms of a fractal representation of the surface correlation function. Results from the two methods agreed within their estimated errors, with the X-ray data showing roughnesses of 1.3 nm, correlation length of 1 μm and fractal parameter (bandwidth) of 0.35. The X-ray methods have a lower cut-off length, are much more rapid for averaged information and are both non-contacting and non-destructive. They also show potential for the study of interface roughness in thin films.
MRS Proceedings, 1991
ABSTRACTWe demonstrate the use of x-ray diffraction to provide accurate compositional information... more ABSTRACTWe demonstrate the use of x-ray diffraction to provide accurate compositional information, together with grazing incidence reflectivity to provide information on layer thicknesses and surface and interface roughnesses, on Si/Si1-xGex superlattice structures of less than 200nm total thickness.The quality of SiGe interfaces has been investigated in superlattices where x varies from 0.1 to 0.5. At low Ge compositions the interfaces are shown to be smooth to a few angstroms. However, as the Ge composition in the SiGe layer approaches 50%, severe roughness is observed at the SiGe to Si interfaces, although the Si to SiGe interfaces remain relatively smooth.Upon annealing for one hour at 850°C the Ge diffuses outwards from the SiGe layers and can be closely modelled by inclusion of a (2.4±0.3)nm linearly graded layer either side of the SiGe layer into a simulation program. The long range roughness at the SiGe to Si interface is lost upon annealing leaving only a short range roughn...
2016 27th Annual SEMI Advanced Semiconductor Manufacturing Conference (ASMC), 2016
This paper describes specific applications illustrating the use of High Resolution X-Ray Diffract... more This paper describes specific applications illustrating the use of High Resolution X-Ray Diffraction (HRXRD) for the inline control of advanced logic technology nodes. More specifically, an innovative strategy based on HRXRD rocking-curve analysis is described for the control of epitaxial SiGe layers on Fully Depleted Silicon On Insulator (FD-SOI) wafers including consideration of the strategy for managing the tilt between the SOI layer and the bulk silicon substrate. Furthermore, the quality of HRXRD Reciprocal Space Maps (RSMs) obtained in an industrial environment is demonstrated and the benefit of RSMs for inline control is discussed.
ECS Meeting Abstracts, 2018
High-Resolution X-ray Diffraction (HRXRD) is a well-established technique for the characterizatio... more High-Resolution X-ray Diffraction (HRXRD) is a well-established technique for the characterization and metrology of epitaxial materials encountered in a variety of important technologies such as nano, opto and power electronics. Traditionally the technique was mainly used for blanket films, and this is still a significant application. However, complex epitaxial nanostructures continue to grow in importance to enable advanced CMOS logic transistors that must combine high-performance with low power consumption and cost with scaled dimensions. Hence, the need to measure and analyze such structures becomes necessary. Several new transistor architectures being considered for logic nodes beyond 10 nm, including more sophisticated FinFETs, gate-all-around (GAA) FETs and the use of fully-depleted silicon-on-insulator (FDSOI) substrates. Equally varied is the range of epitaxial materials proposed, which include SiGe, SiP, Ge as well as III-V materials. Each of these innovations has specific ...
Journal of Applied Crystallography, 2020
Diffraction-based techniques, with either electrons or photons, are commonly used in materials sc... more Diffraction-based techniques, with either electrons or photons, are commonly used in materials science to measure elastic strain in crystalline specimens. In this paper, the focus is on two advanced techniques capable of accessing strain information at the nanoscale: high-resolution X-ray diffraction (HRXRD) and the transmission electron microscopy technique of dark-field electron holography (DFEH). Both experimentally record an image formed by a diffracted beam: a map of the intensity in the vicinity of a Bragg reflection spot in the former, and an interference pattern in the latter. The theory that governs these experiments will be described in a unified framework. The role of the geometric phase, which encodes the displacement field of a set of atomic planes in the resulting diffracted beam, is emphasized. A detailed comparison of experimental results acquired at a synchrotron and with a state-of-the-art transmission electron microscope is presented for the same test structure: a...
Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV, 2021
We have developed a novel in-line solution for the characterization and metrology of high-aspect ... more We have developed a novel in-line solution for the characterization and metrology of high-aspect ratio (HAR) semiconductor structures using transmission small-angle X-ray scattering (SAXS). The solution consists of the Sirius-XCD® tool, NanoDiffract for XCD (NDX) analysis software and high-performance computing infrastructure. The solution provides quantitative information on the orientation and shape of HAR structures, such as 3D NAND channel holes and DRAM capacitors, and can be used for development and control of the critical etch processes used in the formation of such structures. The tool has been designed to minimize expensive cleanroom space without sacrificing performance with typical measurements taking only a few minutes per site. The analysis is done using real-time regression in parallel to the measurements to maximize the throughput of the solution. We will illustrate the key features of the solution using data from a HAR reference wafer and provide results for hole shape and tilt across the wafer together with complimentary data from other techniques. We will also discuss future opportunities for both stand-alone XCD applications and possibilities of XCD-OCD synergies including hybrid metrology in solving complex high-aspect ratio (HAR) and other applications.
A giant magnetoresistance (GMR) multilayer spin-valve stack was investigated utilizing X-ray diff... more A giant magnetoresistance (GMR) multilayer spin-valve stack was investigated utilizing X-ray diffraction (XRD), reflectivity (XRR) and cross-section transmission electron microscopy (XTEM). X-ray reflectivity analysis indicated that layer thickness and density values were within 10% percent of the nominal values with the exception of CoFe and Cu layers, both of which possessed lower than nominal thickness and density. Interface roughness/interdiffusion increased progressively from the substrate (2 A) to the surface (20 A) of the samples, especially with the addition of the antiferromagnetic NiMn layer. The top Ta layer possessed a thin (20 A), low-density oxide and the buried Ta/NiFe interface was deemed to be associated with a thin (18 A) low density Ta layer at the interface. X-ray diffraction analysis showed that the NiFe/CoFe/Cu/CoFe layers possess a single, sharp ( 11 l}fcc/(OO2)hcp fiber texture. A complex structural evolution was found to be associated with deposition of the ...
A combination of specular and off-specular neutron reflectometries was used to measure the buried... more A combination of specular and off-specular neutron reflectometries was used to measure the buried lateral roughness of the reaction-diffusion front in a model extreme ultraviolet lithography photoresist. Compositional heterogeneities at the latent reaction-diffusion front has been proposed as a major cause of line edge roughness in photolithographic features. This work describes the experimental observation of the longitudinal and lateral compositional heterogeneities of a latent image, revealing the buried lateral length scale as well as the amplitude of inhomogeneity at the reaction-diffusion front. These measurements aid in determining the origins of line edge roughness formation, while exploring the material limits of the current chemically amplified photoresists.
ECS Transactions, 2016
With proceeding CMOS device scaling, process technologies become more and more challenging as the... more With proceeding CMOS device scaling, process technologies become more and more challenging as the allowable thermal budget for device processing continuously reduces. This is especially the case during epitaxial growth, where a reduction of the thermal budget is required for a number of potential reasons (e.g. to avoid uncontrolled layer relaxation of strained layers, surface reflow of narrow fin structures, as well as doping diffusion and material intermixing). Different aspects become even more challenging when Ge is used as a high-mobility channel material and when the device concept moves from a FinFET design to a nanowire FET design (also called Gate-All-Around FET). In this contribution we address some of the challenges involved with the integration of high mobility Group IV materials in these advanced device structures.
ECS Journal of Solid State Science and Technology, 2016
MRS Proceedings, 1990
ABSTRACTPC-based software for the rapid simulation of double-axis X-ray rocking curves from epita... more ABSTRACTPC-based software for the rapid simulation of double-axis X-ray rocking curves from epitaxial thin films by solution of the Takagi-Taupin equations is described. The principles of the mathematical model are discussed. Graded layers and interface roughness are treated by piece-wise approximation to linear or quadratic functions and fractional relaxation of each epilayer may be included. The reliability of the data-bases incororated are examined and the requirement for internal consistency demonstrated. Bench-mark tests are reported for various PC-compatible microcomputers. The shift in epilayer peak position, which occurs experimentally on reducing layer thickness at constant composition, is predicted in the simulations and compared with other simulated data in the literature. Detailed studies of generated data have been undertaken and compared with independent simulations and experimental data. Agreement is excellent.
Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2014
Measurement of periodicity and strain in arrays of single crystal silicon and pseudomorphic Si1-x... more Measurement of periodicity and strain in arrays of single crystal silicon and pseudomorphic Si1-xGex/Si fin structures using x-ray reciprocal space maps.
Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2014
Acta Crystallographica Section A Foundations of Crystallography, 1996
Physica B: Condensed Matter, 1998
Grazing incidence diffuse X-ray scattering data from a Co-Cu multilayer with stepped interfaces g... more Grazing incidence diffuse X-ray scattering data from a Co-Cu multilayer with stepped interfaces grown by molecular beam epitaxy on a copper silicide buffer on a silicon substrate has been analysed using a computer code based on a fractal interface within the distorted wave Born approximation. We have extended the theory to include the scattering from a stepped interface and have shown that a single set of structural parameters can be used to obtain an excellent agreement between simulation and experimental data taken under very different X-ray optical conditions. The symmetry of the diffuse scatter on rotation about the surface normal can be explained if it arises from step bunching at the ends of extensive flat terraces. These steps have a self-affine nature, enabling the fractal model to be used successfully. 1998 Elsevier Science B.V. All rights reserved.
Journal of Non-Crystalline Solids, 1999
ABSTRACT
Metrology, Inspection, and Process Control XXXVII
Journal of micro/nanopatterning, materials, and metrology, Mar 22, 2023
MRS Proceedings, 1994
ABSTRACTGrazing incidence X-ray reflectivity may be used to measure surface topography including ... more ABSTRACTGrazing incidence X-ray reflectivity may be used to measure surface topography including roughness and correlation lengths to sub-nanometre precision. A study is made of a technically important surface, a carefully-polished specimen of Zerodur glass-ceramic, which has been measured by diffuse scatter of CuKα X-radiation and atomic-force profilometry methods. The data have been analysed in terms of a fractal representation of the surface correlation function. Results from the two methods agreed within their estimated errors, with the X-ray data showing roughnesses of 1.3 nm, correlation length of 1 μm and fractal parameter (bandwidth) of 0.35. The X-ray methods have a lower cut-off length, are much more rapid for averaged information and are both non-contacting and non-destructive. They also show potential for the study of interface roughness in thin films.
MRS Proceedings, 1991
ABSTRACTWe demonstrate the use of x-ray diffraction to provide accurate compositional information... more ABSTRACTWe demonstrate the use of x-ray diffraction to provide accurate compositional information, together with grazing incidence reflectivity to provide information on layer thicknesses and surface and interface roughnesses, on Si/Si1-xGex superlattice structures of less than 200nm total thickness.The quality of SiGe interfaces has been investigated in superlattices where x varies from 0.1 to 0.5. At low Ge compositions the interfaces are shown to be smooth to a few angstroms. However, as the Ge composition in the SiGe layer approaches 50%, severe roughness is observed at the SiGe to Si interfaces, although the Si to SiGe interfaces remain relatively smooth.Upon annealing for one hour at 850°C the Ge diffuses outwards from the SiGe layers and can be closely modelled by inclusion of a (2.4±0.3)nm linearly graded layer either side of the SiGe layer into a simulation program. The long range roughness at the SiGe to Si interface is lost upon annealing leaving only a short range roughn...
2016 27th Annual SEMI Advanced Semiconductor Manufacturing Conference (ASMC), 2016
This paper describes specific applications illustrating the use of High Resolution X-Ray Diffract... more This paper describes specific applications illustrating the use of High Resolution X-Ray Diffraction (HRXRD) for the inline control of advanced logic technology nodes. More specifically, an innovative strategy based on HRXRD rocking-curve analysis is described for the control of epitaxial SiGe layers on Fully Depleted Silicon On Insulator (FD-SOI) wafers including consideration of the strategy for managing the tilt between the SOI layer and the bulk silicon substrate. Furthermore, the quality of HRXRD Reciprocal Space Maps (RSMs) obtained in an industrial environment is demonstrated and the benefit of RSMs for inline control is discussed.
ECS Meeting Abstracts, 2018
High-Resolution X-ray Diffraction (HRXRD) is a well-established technique for the characterizatio... more High-Resolution X-ray Diffraction (HRXRD) is a well-established technique for the characterization and metrology of epitaxial materials encountered in a variety of important technologies such as nano, opto and power electronics. Traditionally the technique was mainly used for blanket films, and this is still a significant application. However, complex epitaxial nanostructures continue to grow in importance to enable advanced CMOS logic transistors that must combine high-performance with low power consumption and cost with scaled dimensions. Hence, the need to measure and analyze such structures becomes necessary. Several new transistor architectures being considered for logic nodes beyond 10 nm, including more sophisticated FinFETs, gate-all-around (GAA) FETs and the use of fully-depleted silicon-on-insulator (FDSOI) substrates. Equally varied is the range of epitaxial materials proposed, which include SiGe, SiP, Ge as well as III-V materials. Each of these innovations has specific ...
Journal of Applied Crystallography, 2020
Diffraction-based techniques, with either electrons or photons, are commonly used in materials sc... more Diffraction-based techniques, with either electrons or photons, are commonly used in materials science to measure elastic strain in crystalline specimens. In this paper, the focus is on two advanced techniques capable of accessing strain information at the nanoscale: high-resolution X-ray diffraction (HRXRD) and the transmission electron microscopy technique of dark-field electron holography (DFEH). Both experimentally record an image formed by a diffracted beam: a map of the intensity in the vicinity of a Bragg reflection spot in the former, and an interference pattern in the latter. The theory that governs these experiments will be described in a unified framework. The role of the geometric phase, which encodes the displacement field of a set of atomic planes in the resulting diffracted beam, is emphasized. A detailed comparison of experimental results acquired at a synchrotron and with a state-of-the-art transmission electron microscope is presented for the same test structure: a...
Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV, 2021
We have developed a novel in-line solution for the characterization and metrology of high-aspect ... more We have developed a novel in-line solution for the characterization and metrology of high-aspect ratio (HAR) semiconductor structures using transmission small-angle X-ray scattering (SAXS). The solution consists of the Sirius-XCD® tool, NanoDiffract for XCD (NDX) analysis software and high-performance computing infrastructure. The solution provides quantitative information on the orientation and shape of HAR structures, such as 3D NAND channel holes and DRAM capacitors, and can be used for development and control of the critical etch processes used in the formation of such structures. The tool has been designed to minimize expensive cleanroom space without sacrificing performance with typical measurements taking only a few minutes per site. The analysis is done using real-time regression in parallel to the measurements to maximize the throughput of the solution. We will illustrate the key features of the solution using data from a HAR reference wafer and provide results for hole shape and tilt across the wafer together with complimentary data from other techniques. We will also discuss future opportunities for both stand-alone XCD applications and possibilities of XCD-OCD synergies including hybrid metrology in solving complex high-aspect ratio (HAR) and other applications.
A giant magnetoresistance (GMR) multilayer spin-valve stack was investigated utilizing X-ray diff... more A giant magnetoresistance (GMR) multilayer spin-valve stack was investigated utilizing X-ray diffraction (XRD), reflectivity (XRR) and cross-section transmission electron microscopy (XTEM). X-ray reflectivity analysis indicated that layer thickness and density values were within 10% percent of the nominal values with the exception of CoFe and Cu layers, both of which possessed lower than nominal thickness and density. Interface roughness/interdiffusion increased progressively from the substrate (2 A) to the surface (20 A) of the samples, especially with the addition of the antiferromagnetic NiMn layer. The top Ta layer possessed a thin (20 A), low-density oxide and the buried Ta/NiFe interface was deemed to be associated with a thin (18 A) low density Ta layer at the interface. X-ray diffraction analysis showed that the NiFe/CoFe/Cu/CoFe layers possess a single, sharp ( 11 l}fcc/(OO2)hcp fiber texture. A complex structural evolution was found to be associated with deposition of the ...
A combination of specular and off-specular neutron reflectometries was used to measure the buried... more A combination of specular and off-specular neutron reflectometries was used to measure the buried lateral roughness of the reaction-diffusion front in a model extreme ultraviolet lithography photoresist. Compositional heterogeneities at the latent reaction-diffusion front has been proposed as a major cause of line edge roughness in photolithographic features. This work describes the experimental observation of the longitudinal and lateral compositional heterogeneities of a latent image, revealing the buried lateral length scale as well as the amplitude of inhomogeneity at the reaction-diffusion front. These measurements aid in determining the origins of line edge roughness formation, while exploring the material limits of the current chemically amplified photoresists.
ECS Transactions, 2016
With proceeding CMOS device scaling, process technologies become more and more challenging as the... more With proceeding CMOS device scaling, process technologies become more and more challenging as the allowable thermal budget for device processing continuously reduces. This is especially the case during epitaxial growth, where a reduction of the thermal budget is required for a number of potential reasons (e.g. to avoid uncontrolled layer relaxation of strained layers, surface reflow of narrow fin structures, as well as doping diffusion and material intermixing). Different aspects become even more challenging when Ge is used as a high-mobility channel material and when the device concept moves from a FinFET design to a nanowire FET design (also called Gate-All-Around FET). In this contribution we address some of the challenges involved with the integration of high mobility Group IV materials in these advanced device structures.
ECS Journal of Solid State Science and Technology, 2016
MRS Proceedings, 1990
ABSTRACTPC-based software for the rapid simulation of double-axis X-ray rocking curves from epita... more ABSTRACTPC-based software for the rapid simulation of double-axis X-ray rocking curves from epitaxial thin films by solution of the Takagi-Taupin equations is described. The principles of the mathematical model are discussed. Graded layers and interface roughness are treated by piece-wise approximation to linear or quadratic functions and fractional relaxation of each epilayer may be included. The reliability of the data-bases incororated are examined and the requirement for internal consistency demonstrated. Bench-mark tests are reported for various PC-compatible microcomputers. The shift in epilayer peak position, which occurs experimentally on reducing layer thickness at constant composition, is predicted in the simulations and compared with other simulated data in the literature. Detailed studies of generated data have been undertaken and compared with independent simulations and experimental data. Agreement is excellent.
Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2014
Measurement of periodicity and strain in arrays of single crystal silicon and pseudomorphic Si1-x... more Measurement of periodicity and strain in arrays of single crystal silicon and pseudomorphic Si1-xGex/Si fin structures using x-ray reciprocal space maps.
Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2014