Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
  • G01Q60/00—Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
  • G01Q60/18—SNOM [Scanning Near-Field Optical Microscopy] or apparatus therefor, e.g. SNOM probes
  • G01Q60/22—Probes, their manufacture, or their related instrumentation, e.g. holders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/00009—Production of simple or compound lenses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/00009—Production of simple or compound lenses
  • B29D11/00317—Production of lenses with markings or patterns
  • B29D11/00346—Production of lenses with markings or patterns having nanosize structures or features, e.g. fillers
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
  • G01Q70/00—General aspects of SPM probes, their manufacture or their related instrumentation, insofar as they are not specially adapted to a single SPM technique covered by group G01Q60/00
  • G01Q70/08—Probe characteristics
  • G01Q70/10—Shape or taper
  • G01Q70/12—Nanotube tips
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
  • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
  • G11B7/1372—Lenses
  • G11B7/1374—Objective lenses
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
  • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
  • G11B7/1387—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector using the near-field effect

Definitions

• Solid immersion lens and method of making the same.
• the field of the invention is that of immersion lenses for writing or reading optical information to submicron sizes.
• the focusing of an electromagnetic wave by a conventional far-field optical system is normally limited by the Rayleigh criterion to a radius r equal to ⁇ / 2n.sin ⁇ , where r is the focus focus size, ⁇ the length wave of the electromagnetic wave, n the optical index of the material in which said wave propagates, and ⁇ the maximum opening angle of the focusing lens system.
• r is the focus focus size
• ⁇ the length wave of the electromagnetic wave
• n the optical index of the material in which said wave propagates
• ⁇ the maximum opening angle of the focusing lens system
• the first is to increase as much as possible the numerical aperture NA equal to n.sin ⁇ . This is done either by immersion in a liquid of high optical index, or by immersion in a solid material also of high index thanks to a hemispherical or super hemispherical lens. These lenses are said to be solid immersion and are still called "SIL", an acronym for "Solid Immersion Lens", their focal point located in the plane of the hemisphere or the super hemisphere. In practice, these techniques make it possible to focus the light on a smaller focus by a factor n or n 2 than a conventional system keeping a transmission close to 100%, the factor being a function of the shape of the lens. The limitation of this technique is related to the optical index of the material which does not exceed a few units.
• the second possible way is to concentrate this field by so-called optical near-field methods, which exploit the natural localization of the electromagnetic field in the immediate vicinity of a nano-object in the form of a non-propagative field due to the diffraction:
• nano-object means an object of which at least one dimension does not exceed a few tens of nanometers
• the geometry, the spatial distribution of this field and its amplitude are determined firstly by the nature, the geometry and the size of the nano-object, and on the other hand, the polarization and wavelength characteristics of the diffracted light.
• the operation is as follows: an incident wave is sent to a nano-object that diffracts this wave , its size is small in front of the wavelength
• the resulting field has a classical propagative component and a non propagative component which remains localized near the nano-object and called proc field
• This near field can then be modified by a second object, also of small size in front of the wavelength.
• the modification is either a diffraction, a diffusion or a modulation of the field.
• Many applications use the generation and detection of this localized field for the writing of memory points, the characterization, the excitation and the detection of objects, generally of nanometric dimensions located spatially in this near field created by the first nano- object, so-called near-field microscopy, ... Two types of nano-objects are used in practice to generate the localized field.
• the first is a nanometric hole in a generally metallic opaque screen. This can be achieved in planar geometry or in a metal coating on a dielectric support such as an optical fiber or a waveguide. In this geometry, the size of the hearth depends only on the size of the hole.
• the transmission-generated near-field is used by these holes so as to be free from the incident wave, which offers a good signal-to-noise ratio.
• the effect of exaltation by coupling to plasmon modes can also be used to further increase the signal-to-noise ratio between the local field and the propagative field.
• the second way is to use a single nano-object of geometry defined as a nano-sphere, a nano-disk or a paraboloid having at least one confined dimension to concentrate the field close to it.
• the skin effect is not a limitation and the field can potentially be confined to very small dimensions.
• transmission is generally no longer a problem when considering this approach.
• This geometry is widely used for the production of sensors or detectors and for near-field optical microscopy said without opening. The manipulation of the unique 0-dimensional nano-objects remains nevertheless difficult and in practice, nanometric objects having at least one macroscopic dimension are more often used.
• the transmission of the conventional "SNOM" optical tip remains weak as in the case of the previously mentioned aperture points.
• the nano-object which serves as an antenna is produced by etching the metal mask under focused ion beam.
• the idea of the present invention is to use a nano-object called 1D semiconductor material such as a nanowire, a carbon nanotube, a single nano-pillar home of a "SIL" as a high-factor tip on the one hand and as an antenna to increase the optical resolution on the other hand.
• the coupling of the nano-object with the macroscopic world is ensured by the solid immersion lens at the focus of which is positioned this nano-object 1 D.
• a nano-object is characterized inter alia by its form factor. This corresponds to the ratio between the height of the nano-object above its support divided by its diameter in the plane of the support.
• a high ratio allows easier servoing of the device relative to the facing surface along which the device moves and / or allows to relax the constraints of flatness on this surface.
• metallic nano-objects have relatively low form factors, limited to two or three, whereas nano-objects made of semiconductor material can have much higher form factors, of the order of ten.
• the subject of the invention is a solid immersion lens for optical applications, comprising a spherical sector limited by a flat surface, characterized in that a wire or a tube of cylindrical shape made of semiconductor material of which the generatrices are perpendicular to the planar surface and of which at least one dimension is nanometric is disposed on the flat surface, at the focus of said solid immersion lens.
• a light-opaque layer having a central opening of nanometric dimensions is disposed on the plane surface, said aperture being centered on the focus of the solid immersion lens.
• the wire may be silicon, may have at its free end a nanoparticle in gold. It can also be zinc oxide or gailium nitride or be a tubular fullerene.
• the spherical sector is made of material with a high refractive index.
• the invention also relates to an optical device comprising an optical lens according to the preceding provisions, the device then comprising either means for generating an electromagnetic wave arranged to excite the object of nanometric dimensions, or detection means for an electromagnetic wave located at the object of nanometric dimensions.
• the lenses are organized in a matrix comprising several rows of columns, each column comprising several lenses.
• the lens is made by lithography techniques and the method comprises at least a first embodiment which can be carried out in two different ways.
• a first embodiment there is deposited: on a substrate of a first material, a first layer of a second material different from the first material capable of being etched isotropically;
• a second layer of a third material having an opening of nanometric dimensions is deposited on a substrate of a first material capable of being isotropically etched, a second layer of a third material having an opening of nanometric dimensions.
• the method comprises at least the following steps:
• Step 2 production through the opening of the second layer of a cavity in the substrate or the first layer of substantially hemispherical shape by oxidation or isotropic etching;
• Step 3 making a deposit of a fourth material in the hemispherical cavity so as to form a spherical sector;
• Step 4 removing on the second face of the substrate the portion of the substrate covering the spherical sector so as to disengage it;
• Step 5 Making an object of nanometric dimensions in or on the first layer, in the center of the opening of the second layer.
• the first step is followed by a step 1a of producing a nano-pillar centered on the opening of the second layer and step 5 consists in producing the object of nanometric dimensions from this nano- pillar.
• step 5 is followed by a step 5a of growth of a layer of a fifth material on the object of nanometric dimensions.
• step 5 is followed by a step 6 of producing a light-opaque layer sparing the object of nanometric dimensions.
• the third material is an opaque material in the light.
• the first material is silicon
• the second material is silicon or silicon oxide
• the third material is silicon oxide or silicon nitride
• the fourth material is a material with a high refractive index. as silicon oxide or hafnium oxide.
• FIG. 1 represents a view of a lens according to the invention.
• Figures 2 to 7 show the different steps of a first method of producing a lens according to the invention.
• Figures 8a and 8b show the first step of a second method of producing a lens according to the invention.
• Figures 9 to 11 show the different stages of preparation for the realization of the nano-object.
• Figure 1 shows a sectional view of a solid immersion lens according to the invention. It basically includes:
• a sector spherical 1 limited by a flat surface 11.
• This sector is a focusing structure of the solid immersion lens type capable of focusing a light beam incident on an area of the structure, called focal zone or focus 12.
• This lens can be made of silica.
• This lens can be made in planar geometry by lithography techniques, allowing its integration in parallel;
• nano-object An object of nanometric dimensions 2 called nano-object and disposed on the flat surface 11, at the focus of said solid immersion lens.
• This nano-object can serve as a high-form factor tip for applications in which the set comprising the solid immersion lens and the nano-object is scanned in the near-field of a sample to conduct the analysis or to change its nature.
• These 1D nano-objects with high form factor, nanowires and nanotubes are used as high resolution "AFM” points, "AFM” being the acronym for "Atomic Force Microscopy”.
• the lens according to the invention can therefore be used as a multifunctional tip in AFM or "SNOM” applications and possibly “STM", an acronym for "Scanning Tunneling Microscopy".
• the nano-object 2 can:
• the nano-object 2 is chosen from one or more molecules, one or more aggregates, one or more nanowires, one or more nanotubes or fullerenes, whether organic or inorganic, or semiconductors or insulators that can be "functionalized” or not, doped or not, covered with an additional coating or not.
• This coating can be metallic.
• Functionalisation means the ability to modify the nano-object to give it a particular function. In the case of fulierenes, this functionalization can be done inside or outside the carbon cage.
• the metal catalyst nanoparticle at the end of the nanowire, necessary for the growth phase can serve as a nano-object, offset and positioned in the focus of the lens in a controlled manner during the growth step.
• the nature of the nano-object makes it possible to modify the nature of the exploitable signal as a function of the desired application.
• the nano-object is a silicon nanowire
• the presence of a gold catalyst nanoparticle at the end of the wire allows the generation of a plasmon that concentrates the field to a few nanometers only the nanoparticle.
• the control of the growth of the wire makes it possible to position and manipulate the plasmon resonator easily;
• nano-object is a ZnO or GaN nanowire, guided luminescence in the nanowire can be used;
• nano-object is a carbon nanotube or fullerene, the possibility of functionalizing the inside of the tube with a single molecule can be exploited.
• the iuminescence of the individual nanowire is exploited.
• the SIL system associated with the nanowire positioned in its focus makes it possible to effectively couple the light with the nanowire, in order, on the one hand, to excite the photoiuminescence of this individual nanowire, and on the other hand, to collect this luminescence reemitted in the lens. .
• the luminescence of an individual nanowire is further strongly modified by its immediate environment. For example, the presence of a metal surface a few tens of nanometers can "turn off” the luminescence of the nanowire.
• the luminescence of the re-coupled nanowire in the lens it is therefore possible to map the metal surface by scanning the surface with the nanowire used as a near-field optical probe.
• the "SIL" structure associated with the nanowire makes it possible to exploit both ends of the nanowire.
• the end coupled to the "SIL" serves as the point of entry and exit to the light and the free end is able to probe the environment in the near field of the wire.
• the probe makes it possible to map the optical index variation of a surface with a resolution of nanometer size of the probe corresponding to the diameter of the nanowire.
• the nano-object is a carbon nanotube or fullerene
• it can be used as a cage in which nanometric objects with interesting optical properties can be inserted.
• organic molecules such as ⁇ -carotene can be introduced into a carbon nanotube by chemical treatment and cleaning of the molecules in excess.
• the luminescence of this molecule can also be used to image molecular objects deposited on a surface. If the molecule in the nanotube is brought to a few nanometers from another molecule, it can de-energize either radiatively but by yielding its energy to the second molecule in a non-radiative manner by dipolar coupling. The luminescence of the probe molecule is then extinguished, which makes it possible to distinguish the presence of the second molecule and thus to image it or at least to map an optical property.
• the "molecular" size of the probe makes it possible to envisage mapping with a resolution of typically the size of the probe molecule.
• an opaque layer 3 to the light beam is disposed against the face of the structure having the focal zone. It is provided with a nanometer hole 31 of dimension smaller than that of the focal zone 12 of the lens in order to reduce the focal zone of the lens.
• the opening of the opaque layer is self-aligned with the focal zone.
• this layer is monolayer or multilayer depending on the intended applications.
• the "SIL" is used in this case to increase the transmission through the hole.
• the perforated metal mask also serves to align the electric field with the nanowire axis.
• the nano-object is located in the aperture of the opaque layer and on the focal zone of the focusing structure.
• the solid immersion lens according to the invention is connected to means for exciting and using the response of the nano-object. Its means are not shown in Figure 1. Its means of use can be:
• Processing means making it possible to use the response of the nano-object to characterize it, or to characterize the coupling of this response with another nearby object in a sensor-type function;
• Writing means making it possible to use the response of the nano-object to locally modify a particular recording or lithographic layer;
• Reading means making it possible to use the response of the nano-object to locally probe the state of a recording layer or to map a local response on a sample of interest or an exposed lithography layer.
• This type of head combines the advantages of aperture and non-aperture probes in terms of signal-to-noise ratio and resolution while ensuring significant transmission through the lens.
• These heads provide a variety of functions through the various nano-objects positioned at the focus of the "SIL".
• FIGS. 2 to 7 These figures represent sectional views of the lens at course of the different stages of its realization.
• a stack comprising: a first layer 101 of a second material capable of being etched isotropically is produced on a first face of a substrate 100 of a first material; It should be noted that this layer could have been the substrate 100 itself. a second layer 102 formed by at least one third material. This second layer must be both opaque to light and resistant to isotropic etching of the layer lower. Of course, this single layer can be replaced by a stack of layers to obtain the desired effects; This second layer is then made with an aperture of nanometric dimensions 103. The aperture has a diameter smaller than the size of the focusing structure to be produced;
• the first material may be silicon
• the second material may be silicon or silicon oxide
• the third material may be, depending on the sublayers, silicon nitride, silicon oxide and a metal like, for example, gold or platinum.
• a cavity 106 is made through the opening of the second layer in the substrate of substantially hemispherical shape by isotropic etching. This results in a self-alignment of the focal zone with respect to the opening 103;
• a first conformal deposition 107 of a fourth material which may be silicon nitride is produced and then a thick layer 108 of a material with a high optical index such as silicon or hafnium oxide in the hemispherical cavity so as to form the spherical sector of the immersion lens.
• a second "planarization" is then performed on this last deposit; •
• a fourth step illustrated in Figure 6 is removed by anisotropic etching on the rear face of the substrate, the portion of the substrate covering the spherical sector 108 so as to disengage it;
• an object 109 of nanometric dimensions is made in the center of the opening of the second layer.
• This step can be followed by a growth phase of a highly anisotropic nano-object such as a nanowire or a carbon nanotube in the opening on the focal zone.
• a highly anisotropic nano-object such as a nanowire or a carbon nanotube in the opening on the focal zone.
• the step of producing the nano-object can be carried out by a so-called “downward” approach, better known as “top-down” where the nano-object is derived from a transfer method of layers associated with a photo-lithography process.
• the nano-object is then produced in the reported layer by a sequence of standard steps typical of microelectronic technologies.
• This step consists in transferring a layer constituting the material to the deposit 107 by molecular bonding.
• This layer is successively shaped to give birth to the nano-object placed in the focus of the "SiL".
• the method of transferring a layer by molecular bonding to a planar surface composed of several materials is described in US2008 / 0079123. This method allows:
• nano-objects • To associate all types of materials constituting the future nano-object placed in the focus, even those which are not directly feasible in the form of nano-object by deposit and / or direct growth like nanowires, nanotubes, nano-rods still called “nanorods”, nano-dots still called “nanodots”;
• a variant of the "mixed top-down" type of the process described above is to use the added layer as a "pattern" layer, more known in the English terminology of "template” layer for the growth of the nano-object.
• This variant is described in Figures 9, 10 and 11.
• This variant is useful for nanowires where it is necessary to have a crystalline matrix to guide the growth of the wire in the desired direction.
• the orientation of the "template” layer is the same as the preferential direction of growth for the nanowire.
• the crystalline direction is along an axis ⁇ 111>. As indicated in FIG.
• the added layer may consist of a sandwich comprising the "template” layer 110 which may be made of silicon, a catalyst layer 111 which may be made of gold and a protective layer 112 which can oxidize it. of the lower layer.
• the nanowire is grown according to known procedures. This growth step can be preceded by a heat treatment step of the catalyst layer as shown in FIG. 11.
• the advantage of this variant is related to the diameter and the size of the nanowire that can be obtained.
• chemical vapor deposition techniques also called “CVD” meaning “Chemical Vapor Deposition” son are obtained whose diameter is a few tens of nanometers for sizes that can reach or exceed one micron.
• a third nano-pillar 104 is also made in the third material centered on the opening of the second layer as illustrated in FIGS. 8a and 8b.
• Figure 8a is a sectional view and Figure 8b is a perspective view.
• the opening has a smaller diameter than those of the focusing structure to be produced.
• a sacrificial layer is deposited on the second layer and "planarization" is carried out on this layer;
• Steps 2, 3 and 4 are substantially identical to the corresponding steps of the preceding method;
• a nano-object is produced in the opening on the focal zone from a growth phase using the nano-pillar made during the first step as a support.
• This variant can be made from an SOI type substrate or the oxide layer is thick enough to manufacture the "SIL". This thickness can be of the order of 2 or 3 microns.
• the manufacture of the "SIL” is then preceded by the production of a nanometric beam in the crystalline layer of the SOI, which is typically silicon, passing through the opening through which the isotropic etching is carried out.
• the catalyst is deposited in the "SlL” furnace according to one of the processes described.
• the catalyst can already be deposited on the semiconductor layer before etching of the beam, selective grafting can also be carried out, etc.
• the growth of the nanowire or nanotube is carried out.
• the process described above is well suited to obtaining a nano-object made of a mineral material having a given crystalline structure in the form of a nanowire or in the form of a nanobead.
• the manufacturing process can be simplified because the growth direction of the nanotube is controlled by the growth conditions and not by the orientation of the nanotube. the underlying layer. it is then sufficient to locate the appropriate catalyst according to one of the techniques already described.

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• 2007
  • 2007-09-17 FR FR0757641A patent/FR2921192B1/fr not_active Expired - Fee Related
• 2008
  • 2008-09-16 WO PCT/EP2008/062296 patent/WO2009037249A1/fr active Application Filing
  • 2008-09-16 EP EP08804254A patent/EP2210258A1/de not_active Withdrawn
  • 2008-09-16 US US12/678,730 patent/US7940477B2/en not_active Expired - Fee Related
  • 2008-09-16 JP JP2010525326A patent/JP2010539548A/ja active Pending

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