Richard J. Matyi

Ion implantation synthesized copper oxide-based resistive memory devices

Copper oxide resistive memory layers have been synthesized by ion implantation. Devices fabricated from off-stoichiometric Cu2O exhibited unipolar switching in forward/reverse bias without a forming voltage. The on-state conduction of these devices is likely dominated by a metallic filament, which ruptures via Joule heating to transition the device to the high resistance off-state. Technology scaling was achieved by oxygen implanting copper filled vias. The resulting via-based memory devices exhibited unipolar resistive switching down to 48 nm in diameter.

Fabrication of 5-20 nm thick β-W films

A technique to fabricate 5 to 20 nm thick sputter deposited β W films on SiO2 and Si substrates is presented. This is achieved by growing tungsten on a 5 nm SiO2 layer or in an oxygen controlled environment by flowing 2 sccm of O2 during deposition. Resistivity, X-ray photoelectron spectroscopy, X-ray diffraction and reflectivity studies were performed to determine the phase and thickness of tungsten films. These results demonstrate a technique to grow this film on bare Si or a SiO2 substrate, which can enable growth on the bottom of a write unit in a non-volatile spin logic device.

Effect of crystallinity on endurance and switching behavior of HfO x -based resistive memory devices

This paper compares the resistive switching properties of crystalline and amorphous HfOx thin-film resistive memory devices (RMDs), which were fabricated by physical vapor deposition films using two different O2 partial pressures. The crystallinity of the two HfOx samples was verified by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Ni/HfOx/Cu devices fabricated from both 50 nm thick amorphous and crystalline HfOx films exhibited consistent bipolar switching. Average electroforming voltage for the crystalline and amorphous weare <;20 V and <;11 V, respectively. Both devices showed similar average set (Vset) and reset (Vreset) voltages of -2.25 V and 0.35 V, respectively, independent of electrode size and current compliance. Preliminary endurance data shows that the amorphous device shows the better endurance (14,300 cycles) compared to that of the crystalline device (102,000 cycles), which is at about an order of magnitude higher than the endurance of the crystalline device. Switching uniformity for both devices showeds similar trends with dispersions (standard deviation/mean ratio) of about 30% for Vset and Vreset.

Assessment of critical dimension small-angle x-ray scattering measurement approaches for FinFET fabrication process monitoring

Abstract. We have used synchrotron-based critical dimension small-angle x-ray scattering (CD-SAXS) to monitor the impact of hydrogen annealing on the structural characteristics of silicon FinFET structures fabricated using self-aligned double patterning on both bulk silicon and silicon-on-insulator (SOI) substrates. H2 annealing under different conditions of temperature and gas pressure allowed us to vary the sidewall roughness and observe the response in the two metrology approaches. In the case of the simpler bulk Si FinFET structures, the CD-SAXS measurements of the critical dimensions are in substantive agreement with the top–down critical dimension scanning electron microscopy metrology. Corresponding characterizations on SOI-based FinFET structures showed less agreement, which is attributed to the more complex structural model required for SOI FinFET CD-SAXS modeling. Because sidewall roughness is an important factor in the performance characteristics of Si FinFETs, we have compared the results of roughness measurements using both critical dimension atomic force microscopy (CD-AFM) and CD-SAXS. The measurements yield similar estimates of sidewall roughness, although the CD-AFM values were typically larger than those generated by CD-SAXS. The reasons for these differences will be discussed.

Coefficient of thermal expansion (CTE) in EUV lithography: LER and adhesion improvement

Spin-on underlayers are currently being employed by the lithographic industry to improve the imaging performance of EUV resists. In this work, multiple examples have shown improved line-edge roughness (LER) of an open-source resist using new open-source underlayers in comparison to a primed silicon substrate. Additionally, several experiments demonstrate better resist adhesion on underlayers that have lower coefficients of thermal expansion (CTE). Both organic and inorganic underlayers provide better resist LER when their CTE is lower.

Implementation of statistical dynamic diffraction theory for defective semiconductor heterostructure modelling

Statistical dynamic diffraction theory (SDDT) provides the ability to model defect-induced structures in high-resolution X-ray diffraction analyses by incorporating both coherent (dynamic) and incoherent (kinematic) scattering. Current treatments of SDDT are mathematically intensive and may not provide sufficient detail regarding the implementation of the theory in practice. This paper discusses the implementation of SDDT and the modifications that allow for successful SDDT analyses of fully relaxed SiGe on Si.

Advances in CD‐Metrology (CD‐SAXS, Mueller Matrix based Scatterometry, and SEM)

Scanning Electron Microscopy (SEM) has been a mainstay of critical dimension (CD) metrology since the inception of integrated microelectronics, due to its inherent high resolution capability and relative ease of interpretation. However, as device dimensions continue to shrink, and non‐planar devices become integrated into process flows (e.g., finFETs), the need to identify and develop successor technologies becomes essential. Here, we report progress on the development of two innovative technologies proposed for CD measurement, and assess their viability for high volume manufacturing applications. Finally, we describe recent efforts to extend the life of conventional CD‐SEM.Small Angle X‐ray Scattering (SAXS) also offers Angstrom‐level resolution, is non‐destructive, and requires no additional preparation steps. Performed in either transmission or reflection mode, this method is particularly suitable for arrayed structures and non‐planar devices. Whereas direct imaging methods provide a complete descripti...

X‐ray Scattering Methods for Porosity Metrology of Low‐k Thin Films

X‐ray scattering is a non‐destructive analytical technique capable of detecting electron density fluctuations in mesoporous and nanoporous structures. X‐ray methods have the potential to provide fully quantitative porosity analyses of open and closed pore structures. Specular x‐ray reflectivity (XRR) offers accurate measurement of thickness, density, and roughness of uniformly deposited thin films. Diffuse scattering techniques are also studied by manipulation of the scattering geometry and approximation of the average pore size and pore size distribution. Effects of refraction and reflection from the surface and buried interface are corrected via the Distorted Wave Born Approximation (DWBA). Distortion of the scattering profile due to slit smearing is also taken into account to obtain an accurate interpretation of diffuse scattering phenomena. Preliminary results for average pore size and pore size distribution of PECVD‐prepared SiCOH thin films with both open and closed pore structures are reported, and...

High mobility Ge-channel formation by localized/selective liquid phase epitaxy (LPE) using Ge+B plasma ion implantation and laser melt annealing

Localized Ge and SiGe high mobility channel material is needed for 10nm node and beyond CMOS technology. Thin direct >50% SiGe selective epi followed by oxidation for Ge condensation, 100% Ge selective epi or thermal mixing are methods that require a hard mask and epi interface defects with rough surfaces are always an issue. An alternative approach to epi is using photoresist masking as proposed by Borland et al [1] with Ge-infusion doping (dose controlled deposition), a very high dose implantation technique that leads to amorphous deposition followed by low temperature SPE of the amorphous Ge surface layer but residual interface defects remained.

Diffusion activation energy of cadmium in thin film CuInGaSe 2

Diffusivity and activation energy of cadmium in copper indium gallium diselenide (CuInGaSe2 or CIGS) thin films were investigated by annealing solar-grade SLG/Mo/CIGS/CdS samples of two different CIGS thicknesses at temperatures between 150° C and 325° C. Diffusion profiles of cadmium volume and grain boundary were investigated by dual-beam time-of-flight secondary ion mass spectroscopy. A relationship between the cadmiums volume and grain boundary diffusion coefficients and their activation energies at a given annealing temperature was established using LeClaires grain boundary diffusion model. The data also provide evidence that cadmium diffusion may be strongly modulated by a gallium gradient seen both laterally at the interface and in the bulk in solar-grade CIGS material.