Scanning probe microscopy characterisation of masked low energy implanted nanometer structures (original) (raw)
Related papers
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2009
Nanopatterning of silicon surfaces by means of He + ion implantation through self-organized colloidal masks is reported for the first time. Nanosphere lithography (NSL) masks with mask openings of 46-230 nm width were deposited on Si(1 0 0) wafers. He + ions were implanted through these masks in order to induce a local cavity formation and Si surface swelling. The surface morphology and the subsurface structure were studied using atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (XTEM), respectively, as a function of mask and implantation parameters. It is demonstrated that regular arrays of both individual hillocks and trough-like circular rings can be generated.
Patterned microstructures formed with MeV Au implantation in Si(100)
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2006
Energetic (MeV) Au implantation in Si(1 0 0) (n-type) through masked micropatterns has been used to create layers resistant to KOH wet etching. Microscale patterns were produced in PMMA and SU(8) resist coatings on the silicon substrates using P-beam writing and developed. The silicon substrates were subsequently exposed using 1.5 MeV Au 3+ ions with fluences as high as 1 • 10 16 ions/cm 2 and additional patterns were exposed using copper scanning electron microscope calibration grids as masks on the silicon substrates. When wet etched with KOH microstructures were created in the silicon due to the resistance to KOH etching cause by the Au implantation. The process of combining the fabrication of masked patterns with P-beam writing with broad beam Au implantation through the masks can be a promising, cost-effective process for nanostructure engineering with Si.
physica status solidi (a), 2007
We propose an original approach called "stencil-masked ion implantation process" to perform a spatially localized synthesis of a limited number of Si nanoparticles (nps) within a thin SiO 2 layer. This process consists in implanting silicon ions at ultra-low energy through a stencil mask containing a periodic array of opened windows (from 50 nm to 2µm). After the stencil removal, a thermal annealing is used to synthesize small and spherical embedded nps. AFM observations show that the stencil windows are perfectly transferred into the substrate without any clogging or blurring effect. The samples exhibit a 3nm localized swelling of the regions rich in Si nps. Moreover, photoluminescence (PL) spectroscopy shows that due to the quantum confinement only the implanted regions containing the Si nps are emitting light.
Investigation of inhomogeneous structures of near-surface-layers in ion-implanted silicon
The ion implantation as a subject of investigations attracts increasing interest because of its technological applications. For example, the ion implantation and the adequate thermal treatment are the basic processes for fabrication of a new so-called delta-BSF solar cell. In this silicon solar cell, the continuous sub-structure of modified material _planar amorphous-like layer of nanometric thickness with very thin transition zones. is inserted into the single-crystal emitter. From earlier high resolution electron microscopy studies, it is evident that these two Si phases coexist in the form of well-defined layers separated by sharp heterointerfaces wZ.T. Kuznicki, J. Thibault, F. Chautain-Mathys, S. De Unamuno, Towards ion beam processed single-crystal Si solar cells with a very high efficiency, E-MRS Spring Meeting, Strasbourg, France, First Polish–Ukrainian Symposium, New Photovoltaic Materials for Solar Cells, October 21–22, Krakow, Poland, 1996.x. The aim of this paper is the further structural characterisation of silicon single crystal with buried ‘amorphous’ layer. The non-destructive X-ray diffraction methods as well as the transmission electron microscopy were used to investigate the quality of the a-Sirc-Si heterointerfaces, structural homogeneity of the layers and distribution of the stress field. The measurements were carried out on an initial, as-implanted and annealed material. The _100:-oriented Si single crystals were implanted with 180 keV energy P ions at room temperature.
Shape transition of nanostructures created on Si(1 0 0) surfaces after MeV implantation
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2006
We have studied the modification in the Surface morphology of the Si(100) surfaces after 1.5 MeV Sb implantation. Scanning Probe Microscopy has been utilized to investigate the ion implanted surfaces. We observe the formation of nano-sized defect features on the Si surfaces for the fluences of 1×10 13 ions/cm 2 and higher. These nanostructures are elliptical in shape and inflate in size for higher fluences. Furthermore, these nanostructures undergo a shape transition from an elliptical shape to a circular-like at a high fluence. We will also discuss the modification in surface roughness as a function of Sb fluence.
Nanotechnology, 2009
Potassium hydroxide (KOH) etching of a patterned 100 oriented silicon wafer produces V-shaped etch pits. We demonstrate that the remaining thickness of silicon at the tip of the etch pit can be reduced to ∼5 μm using an appropriately sized etch mask and optical feedback. Starting from such an etched chip, we have developed two different routes for fabricating 100 nm scale slits that penetrate through the macroscopic silicon chip (the slits are ∼850 μm wide at one face of the chip and gradually narrow to ∼100-200 nm wide at the opposite face of the chip). In the first process, the etched chips are sonicated to break the thin silicon at the tip of the etch pit and then further KOH etched to form a narrow slit. In the second process, focused ion beam milling is used to etch through the thin silicon at the tip of the etch pit. The first method has the advantage that it uses only low-resolution technology while the second method offers more control over the length and width of the slit. Our slits can be used for preparing mechanically stable, transmission electron microscopy samples compatible with electrical transport measurements or as nanostencils for depositing nanowires seamlessly connected to their contact pads.
Journal of Applied Physics, 2004
In silicon nanocrystal based metal-oxide-semiconductor memory structures, tuning of the electron tunneling distance between the Si substrate and Si nanocrystals located in the gate oxide is a crucial requirement for the pinpointing of optimal device architectures. In this work it is demonstrated that this tuning of the ''injection distance'' can be achieved by varying the Si ϩ ion energy or the oxide thickness during the fabrication of Si nanocrystals by ultralow-energy silicon implantation. Using an accurate cross-section transmission electron microscopy ͑XTEM͒ method, it is demonstrated that two-dimensional arrays of Si nanocrystals cannot be positioned closer than 5 nm to the channel by increasing the implantation energy. It is shown that injection distances down to much smaller values ͑2 nm͒ can be achieved only by decreasing the nominal thickness of the gate oxide. Depth profiles of excess silicon measured by time-of-flight secondary ion mass spectroscopy and Si nanocrystal locations determined by XTEM are compared with Monte-Carlo simulations of the implanted Si profiles taking into account dynamic target changes due to ion implantation, ion erosion, and ion beam mixing. This combination of experimental and theoretical studies gives a safe explanation regarding the unique technological route of obtaining Si nanocrystals at distances smaller than 5 nm from the channel: the formation of nanocrystals requires that the interface mixing due to collisional damage does not overlap with the range profile to the extent that there is no more a local maximum of Si excess buried in the SiO 2 layer.
Depth positioning of silicon nanoparticles created by Si ULE implants in ultrathin SiO/sub 2/
SCS 2003 International Symposium on Signals Circuits and Systems Proceedings (Cat No 03EX720) IIT-02, 2002
Silicon nanocrystals buried in a thin oxide can be used as charge storage elements and be integrated in standard CMOS technology to fabricate new non-volatile memory devices. In this geometry, the control of the distances between the nanocrystals layer and the two electrodes, the channel and the gate, of the MOS determines the final characteristics of the device (writeerase and retention times). In this work, we report on a systematic study of the effect of varying the beam energy (0.65 -2 keV) and the dose (10 15 -10 16 cm -2 ) on the positioning of 2Darrays of nanocrystals within 10 nm thick oxide after annealing at 950 and 1050°C. For this, different Transmission Electron Microscopy (TEM) methods have been used including High Resolution Electron Microscopy (HREM) for imaging isolated nanocrystals and Fresnel contrast imaging of populations of nanocrystals. Our results show that the "injection distance" can be precisely tuned in the 5-8 nm range by varying the beam energy. Moreover, very large swelling of the SiO 2 layer has been observed when increasing the implanted dose which could be the result of a partial oxidation of the Si ncs layer and/or of the SiO 2 /Si interface.
Journal of Applied Physics, 2004
In silicon nanocrystal based metal-oxide-semiconductor memory structures, tuning of the electron tunneling distance between the Si substrate and Si nanocrystals located in the gate oxide is a crucial requirement for the pinpointing of optimal device architectures. In this work it is demonstrated that this tuning of the ''injection distance'' can be achieved by varying the Si ϩ ion energy or the oxide thickness during the fabrication of Si nanocrystals by ultralow-energy silicon implantation. Using an accurate cross-section transmission electron microscopy ͑XTEM͒ method, it is demonstrated that two-dimensional arrays of Si nanocrystals cannot be positioned closer than 5 nm to the channel by increasing the implantation energy. It is shown that injection distances down to much smaller values ͑2 nm͒ can be achieved only by decreasing the nominal thickness of the gate oxide. Depth profiles of excess silicon measured by time-of-flight secondary ion mass spectroscopy and Si nanocrystal locations determined by XTEM are compared with Monte-Carlo simulations of the implanted Si profiles taking into account dynamic target changes due to ion implantation, ion erosion, and ion beam mixing. This combination of experimental and theoretical studies gives a safe explanation regarding the unique technological route of obtaining Si nanocrystals at distances smaller than 5 nm from the channel: the formation of nanocrystals requires that the interface mixing due to collisional damage does not overlap with the range profile to the extent that there is no more a local maximum of Si excess buried in the SiO 2 layer.
Crystallography Reports, 2013
The influence of the implantation of silicon single crystals by fluorine, nitrogen, oxygen, and neon ions on the distribution of strain and the static Debye-Waller factor in the crystal lattice over the implanted layer depth has been investigated by high resolution X ray diffraction. The density depth distribution in the surface layer of native oxide has been measured by X ray reflectometry. Room temperature implantation conditions have ensured the equality of the suggested ranges of ions of different masses and the energies trans ferred by them to the target. It is convincingly shown that the change in the structural parameters of the radi ation damaged silicon layer and the native oxide layer depend on the chemical activity of the implanted ions.