Robert Mroczyński

Application of plasma enhanced chemical vapor deposition silicon oxynitride layers in nonvolatile semiconductor memory devices

In this paper, the authors present the new double gate dielectric structure for the nonvolatile semiconductor memory (NVSM) devices which is based of hafnium dioxide (HfO2). The novelty of this structure relays on the introduction of ultrathin silicon oxynitride (SiOxNy) formed by plasma enhanced chemical vapor deposition (PECVD). Fabricated test structures with the PECVD layers show repetitious behavior of the hysteresis characteristics in comparison to structure with silicon dioxide as the tunnel (bottom) dielectric, which the stability of hysteresis loop is observed after completing first stressing loop. Moreover, the memory window expressed as the flat-band voltage shift versus stress voltage is very wide (1.68V) and the maximum charge which can be stored by the double gate dielectric stack is of the order of 6×1012(cm−2). Comparison of current density versus gate voltage characteristics of investigated metal-insulator-semiconductor systems demonstrated significantly a decrease of the leakage current ...

Reliability issues of double gate dielectric stacks based on hafnium dioxide (HfO2) layers for non-volatile semiconductor memory (NVSM) applications

Abstract In this study, we present selected reliability issues of double gate dielectric stacks for non-volatile semiconductor memory (NVSM) applications. Fabricated gate structures were consisted of PECVD silicon oxynitride layer (SiO x N y ) as the pedestal layer and hafnium dioxide layer (HfO 2 ) as the top gate dielectric. In the course of this work, obtained MIS structures were investigated by means of current–voltage characteristics, as well as applying dc stresses in constant current (CCS) and voltage (CVS) mode. Presented results have shown that the application of ultra-thin PECVD silicon oxynitride layer results in significant increase of breakdown voltage value in comparison to MIS structure with only hafnia as the gate dielectric. Moreover, due to the high temperature annealing of deposited SiO x N y layers, MIS device demonstrates much lower leakage currents, as well as higher breakdown voltage values in comparison to device with ‘as-deposited’ SiO x N y bottom layer. The results also proved larger immunity to dc stresses and better retention characteristics of MIS devices with ‘annealed’ oxynitride, in comparison to ‘as-deposited’ pedestal layer.

Effect of Sample Elevation in Radio Frequency Plasma Enhanced Chemical Vapor Deposition (RF PECVD) Reactor on Optical Properties and Deposition Rate of Silicon Nitride Thin Films

In this paper we investigate influence of radio frequency plasma enhanced chemical vapor deposition (RF PECVD) process parameters, which include gas flows, pressure and temperature, as well as a way of sample placement in the reactor, on optical properties and deposition rate of silicon nitride (SiNx) thin films. The influence of the process parameters has been determined using Taguchi’s orthogonal tables approach. As a result of elevating samples above the electrode, it has been found that deposition rate strongly increases with distance between sample and the stage electrode, and reaches its maximum 7 mm above the electrode. Moreover, the refractive index of the films follows increase of the thickness. The effect can be observed when the thickness of the film is below 80 nm. It has been also found that when the deposition temperature is reduced down to 200 °C, as required for many temperature-sensitive substrate materials, the influence of the substrate material (Si or oxidized Si) can be neglected from the point of view of the properties of the films. We believe that the obtained results may help in designing novel complex in shape devices, where optical properties and thickness of thin plasma-deposited coatings need to be well defined.

Reactive magnetron sputtered hafnium oxide layers for nonvolatile semiconductor memory devices

The feasibility of the application of double-gate dielectric stacks with fabricated by r.f. reactive magnetron sputtering hafnium oxide layers in nonvolatile semiconductor memory (NVSM) devices was investigated. Significant retention time was demonstrated. A very broad memory window (extrapolated at 10 years) of flat-band voltage (UFB) value of the order of 2.6 V was obtained. Moreover, the stability of the electrical characteristics of metal–insulator–semiconductor structures after gamma and electron irradiation have been observed, which proved that the investigated double-gate dielectric stacks are promising for future applications in NVSM radiation-hard devices.

Silicon Oxynitride Layers Fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) for CMOS Devices

This work is devoted to the technology and characterization of silicon oxynitride layers (SiOxNy) formed by Plasma Enhanced Chemical Vapor Deposition (PECVD). In the course of this work thermal stability of deposited layers was also examined. Expected changes in structure, chemical composition and electro-physical properties of the obtained layers were investigated by means of spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and electrical characterization of manufactured test structures (metal-insulatorsemiconductor (MIS) capacitors and MISFETs). Selected process parameters were chosen to fabricate SiOxNy layers which were introduced into MIS devices with double gate dielectric stack (based of hafnium dioxide). Electrical characterization of such MIS structures with PECVD silicon oxynitride have shown a feasibility of application of obtained system in non-volatile semiconductor memory (NVSM) devices.

Silicon nitride (SiNx) plasma deposition on optical fiber sensors: coating symmetry perspective

This paper discusses the influence of coating long-period gratings with a silicon nitride thin overlay on the grating’s spectral response. The overlays have been obtained with a radio frequency plasma enhanced chemical vapor deposition method. During the experiment, the structures were positioned on various heights over the electrode using specially developed sample holder. The results of the experiment show that the investigated long period grating structures have increased their sensitivity to variations of external medium refractive index in the range of nD=1.33 to 1.43 RIU. The relation between the height at which the long period grating was placed over the electrode and the deposited overlay symmetry is discussed. The highest sensitivity of 2080 nm/RIU has been observed for the grating placed at the highest positions of the holder out of the examined range of 3 to 8 mm over the electrode. This overlay also shows the highest symmetry around the fiber.

Improvement of immunity on MeV electron radiation of MOS structures by means of ultra-shallow fluorine implantation

In this study, we present novel method for improvement of immunity on MeV electron radiation of MOS structures by means of ultra-shallow fluorine implantation from r.f. CF4 plasma. For the purposes of comparison of electrical behavior, MOS capacitors were manufactured. One MeV electron radiation on fabricated MOS devices, was adopted. Obtained results have shown that fluorination of silicon surface results in significant decrease of leakage current as well as uniform distribution of breakdown voltage values. Moreover, capacitance–voltage measurements of MOS structures after fluorine implantation exhibit no frequency dispersion in comparison to reference structures. Presented results demonstrated feasibility of application of ultra-shallow fluorine implantation from r.f. CF4 plasma in technology for radiation-hard silicon devices.

Ultra-shallow fluorine and nitrogen implantation from r.f. plasma and its effect on electro-physical parameters of Al/HfO2/Si MOS structures

This study described a novel and original method of ultra-shallow fluorine and nitrogen implantation from radio frequency (RF = 13,56MHz) CF4 and NH3 plasmas, performed in classical RIE / PECVD reactors. The performed experiments indicate that ultra-shallow implantation of high concentration of fluorine and nitrogen ions by using r.f. plasma reactors (PECVD ad RIE) is feasible. It is also possible to control the implantation process parameters, ie implantation depth and maximum concentration, by controlling the parameters of the plasma processes. Electrical characterization of MOS structures with HfO2 layer as a gate dielectric, shows that samples implanted with nitrogen, have the best insulating properties, better even the reference sample. Samples prepared by fluorine implantation, exhibit much worse I-V behavior for low, medium and high electric fields, than all samples studied in this article. This samples exhibit the highest leakage currents, too.

Characterization of thin Gd2O3 magnetron sputtered layers

Reactive magnetron sputtering technique using O2/Ar gas mixture was used to deposit Gd2O3 layers. Following metallization process of Al allowed to create MIS structures, which electrical parameters (κ, Dit, UFB, ρ, etc.) were measured using high frequency C-V equipment. Created layers exhibit high permittivity (κ≈12) at 100kHz. I-V measurements point out on maximum electric break down field Ebr≈0.4 MV/cm and maximum break down voltage Ubr ≈ 16V. Layers were morphologically tested using AFM technique (Ra ≈ 0.5÷2nm). Layer thicknesses as well as refractive indexes (RI ≈ 1.50÷2.05) were estimated using ellipsometry measurements.

Characterization of thin Gd2O3magnetron sputtered layers

Reactive magnetron sputtering technique using O2/Ar gas mixture was used to deposit Gd2O3 layers. Following metallization process of Al allowed to create MIS structures, which electrical parameters (κ, Dit, UFB, ρ, etc.) were measured using high frequency C-V equipment. Created layers exhibit high permittivity (κ≈12) at 100kHz. I-V measurements point out on maximum electric break down field Ebr≈0.4 MV/cm and maximum break down voltage Ubr ≈ 16V. Layers were morphologically tested using AFM technique (Ra ≈ 0.5÷2nm). Layer thicknesses as well as refractive indexes (RI ≈ 1.50÷2.05) were estimated using ellipsometry measurements.