WO2004074902A1 - Variable-focus lens comprising a silicon or gallium arsenide substrate - Google Patents

Variable-focus lens comprising a silicon or gallium arsenide substrate Download PDF

Info

Publication number
WO2004074902A1
WO2004074902A1 PCT/FR2004/000286 FR2004000286W WO2004074902A1 WO 2004074902 A1 WO2004074902 A1 WO 2004074902A1 FR 2004000286 W FR2004000286 W FR 2004000286W WO 2004074902 A1 WO2004074902 A1 WO 2004074902A1
Authority
WO
WIPO (PCT)
Prior art keywords
silicon
lens according
insulating layer
titanium
substrate
Prior art date
Application number
PCT/FR2004/000286
Other languages
French (fr)
Inventor
Frédéric GAILLARD
Marc Plissonnier
Pierre Juliet
Original Assignee
Commissariat A L'energie Atomique
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Commissariat A L'energie Atomique filed Critical Commissariat A L'energie Atomique
Publication of WO2004074902A1 publication Critical patent/WO2004074902A1/en

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/004—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/12—Fluid-filled or evacuated lenses
    • G02B3/14—Fluid-filled or evacuated lenses of variable focal length

Definitions

  • Variable focal length lens comprising a silicon or gallium arsenide substrate.
  • the invention relates to a lens with variable focal length comprising an electrically insulating layer formed on at least part of a support, means for forming on the insulating layer a hydrophobic surface and a drop of an electrically insulating liquid arranged on the hydrophobic surface. .
  • Varifocal lenses are more and more used in imaging devices and in particular in cameras, photographic devices or microscopes.
  • the principle consists in immersing a microlens consisting of a drop of an electrically insulating liquid in a cell filled with a conductive organic liquid and immiscible with the insulating liquid.
  • the application of a potential difference across the cell makes it possible to obtain a lens with variable focal length, by varying the shape of the drop.
  • the document JP-A-2001013306 describes a variable focal lens device comprising a cell filled with a conductive liquid.
  • An insulating layer is arranged on the lower surface of the cell.
  • a circular part of the insulating layer is exposed so as to come into contact with a drop of insulating liquid while the complementary part of the insulating layer is covered by a surface layer whose affinity with the drop of insulating liquid is less than the one with the insulating layer.
  • Means application of a potential difference make it possible to modify the shape of the drop.
  • the known substrates for producing such lenses with variable focal length are generally made of stainless steel, alumina, plastic material or glass.
  • a cavity generally conical in shape and intended to center the drop of insulating liquid, is produced in the substrate.
  • a layer serving as electrical insulator made of fluoropolymers such as Teflon® sold by the company Tetrachim, is deposited on this substrate by heat-bonding, then it is machined to obtain a thickness of approximately 2 microns.
  • These substrates do not, however, allow a good surface appearance or reproducible shapes to be obtained. Indeed, the machining of Teflon® and the formation of the cavity, for example by EDM for a stainless steel substrate, generate a variation in the thickness of the insulating layer and significant surface roughness in the substrate.
  • the object of the invention is to make a variable focal length lens easy to produce and comprising a support having a satisfactory surface appearance and on which thin layers of controlled thickness can be deposited. According to the invention, this object is achieved by the fact that the support consists of a silicon or gallium arsenide substrate.
  • the support comprises a conical cavity intended to contain the drop.
  • the silicon or gallium arsenide substrate is covered by an electrically conductive layer.
  • the conductive layer consists of a material chosen from the group comprising polycrystalline silicon, tungsten, platinum, copper, titanium, cobalt, tantalum, germanium, molybdenum, ruthenium, silicides of tungsten, titanium, cobalt or germanium and nitrides of titanium or tantalum.
  • the insulating layer consists of a dielectric material having a permittivity greater than 3.9.
  • Figure 1 is a sectional view of a first embodiment of a part of a variable focal lens according to the invention.
  • Figure 2 is a sectional view of a second embodiment of part of a lens according to the invention.
  • Figure 3 is a sectional view of a third embodiment of part of a lens according to the invention.
  • a variable focal length lens according to the invention comprises an electrically insulating layer formed on at least part of a support, means for forming on the insulating layer a hydrophobic surface and a drop of an electrically insulating liquid disposed on the hydrophobic surface.
  • the support consists of a silicon or gallium arsenide substrate.
  • a drop 1 of an electrically insulating liquid is placed on a hydrophobic surface 1 a of an electrically insulating layer 2, preferably in an enclosure filled with a conductive liquid (not shown ).
  • the drop 1 corresponds to a microlens whose focal length can vary continuously using the electrowetting phenomenon.
  • the wettability of the drop 1 increases appreciably in the presence of an electric field due to an electric voltage applied between a first electrode disposed under the drop 1 and a second electrode or the conductive liquid.
  • the two respectively insulating and conducting liquids are transparent, immiscible, and they have different refractive indices.
  • the hydrophobic surface 1a has a low wettability vis-à-vis the conductive liquid and a high wettability vis-à-vis the insulating liquid.
  • the insulating layer 2 is preferably made of silicon oxide doped with carbon (SiOCH) or of carbofluorinated compounds (CF X with x between 1 and 4), so as to make its surface hydrophobic.
  • the insulating layer 2 is arranged on at least part of a support intended to form the first electrode making it possible to apply an electrical voltage with the conductive liquid.
  • the support consists of a substrate 4 made of silicon or gallium arsenide, said substrate preferably having a thickness of less than 1 mm.
  • the electrical conductivity of the substrate 4 made of silicon or gallium arsenide can be reinforced by an electrically conductive layer covering it or else by doping. The doping of the support thus prevents the deposition of an additional electrically conductive thin layer and it optionally allows the first electrode to be produced intrinsically in the support.
  • the support consists of a substrate 4 of silicon or of gallium arsenide covered by an electrically conductive layer 5.
  • the electrically conductive layer is a first embodiment shown in FIG. 2, the support consists of a substrate 4 of silicon or of gallium arsenide covered by an electrically conductive layer 5.
  • the electrically conductive layer 5 is preferably made of a material chosen from the group comprising polycrystalline silicon, tungsten, platinum, copper, titanium, cobalt, tantalum, germanium, molybdenum, ruthenium, tungsten silicides , titanium, cobalt or germanium and nitrides of titanium or tantalum.
  • the electrically conductive layer 5 preferably has a thickness of between 50 nm and 1000 nm while the substrate 4 preferably has a thickness of less than 1 mm.
  • An insulating layer 2 is disposed on the electrically conductive layer 5 of the support. It preferably has a thickness less than or equal to 2 micrometers and it is preferably made of a dielectric material having a permittivity greater than 3.9.
  • the dielectric material is, for example, chosen from the group comprising silicon nitride, an amorphous silicon doped with carbon, an amorphous silicon doped with carbon and nitrogen, oxides of silicon, tantalum, titanium, hafnium, zirconium, alumina, titanium oxide and strontium, titanium oxide and barium, titanium oxide, zirconium and lead, better known as PZT, and titanium oxide, barium and strontium, also known as SBT.
  • a hydrophobic layer 3 is disposed on the insulating layer 2 so as to form the hydrophobic surface 1 a which is preferably made of carbofluorinated compounds, that is to say in CFx, with x between 1 and 4, or in amorphous carbons, that is to say CHx, with x comprised between 1 and 4.
  • the hydrophobic layer 3 makes it possible to obtain a drop angle greater than 90 °, possibly even reaching 140 °.
  • the insulating layer 2 has a permittivity greater than 3.9 makes it possible, in particular, to reduce the electric voltage applied to the drop 1 by a factor of 100 compared to an insulating layer according to the prior art and more particularly compared with an insulating layer of Teflon®.
  • a substrate 4 of silicon or of gallium arsenide has the advantage of being able to use the techniques of microelectronics, in particular the methods of depositing thin layers and of etching.
  • silicon and gallium arsenide have cleavage planes which allow to maintain a very low surface roughness, which facilitates deposits of thin layers with controlled thickness and better quality etchings.
  • the deposition of the electrically conductive layer 5 on the substrate 4 can be carried out by a vapor phase deposition of the PVD, CVD, PECVD or MOCVD type, respectively known by the English name of "Physical
  • Vapor Deposition "," Chemical Vapor Deposition “, Plasma Enhanced Chemical Vapor Desposition”, and Metal-Organic Chemical Vapor Deposition ". This allows deposits to be made whose thickness varies by less than 2% over a diameter of 200mm. The uniformity of the thickness of the deposit thus makes it possible to obtain a support having a stable electrical conductivity.
  • the substrate 4 comprises a conical cavity 6 in which the drop 1 is arranged.
  • the conical cavity 6 keeps the drop 1 at a given location on the support.
  • the slope of the cavity 6 is preferably determined according to a centering method described in the document WO-A1 -0058763.
  • the fact of using a silicon or gallium arsenide substrate makes it possible to form the cavity 6, by virtue of a process resulting from microelectronics, such as plasma etching.
  • a resin deposit and a photolithography of 365 nm are carried out on a silicon substrate 4, so as to produce the conical cavity 6 by dry etching with bromide and chlorine (HBr and Cl 2 ) or with hexafluoride of sulfur (SF 6 ), in a high or medium density plasma reactor, of the plasma type by inductive coupling (Inductive Coupling Plasma or ICP), ion etching
  • this etching technique on a substrate makes it possible to very precisely control the slope of the cone of the cavity 6, within ⁇ 1 °, while generating a low surface roughness.
  • the roughness is preferably less than 50nm.
  • the insulating layer 2 is deposited uniformly inside the cone.
  • a silicon substrate also makes it possible to simplify the method of manufacturing a lens with variable focal length, to reduce the manufacturing costs and to ensure a reproducible production of lenses with variable focal length.
  • a variable focal lens according to the invention can, for example, be used in cameras, photographic cameras, microscopes.

Abstract

The invention relates to a variable-focus lens comprising an electrically-insulating layer (2) which is formed on at least one part of a support, means for forming a hydrophobic surface (1a) on the aforementioned insulating layer (2) and a drop (1) of an electrically-insulating liquid which is disposed on the hydrophobic surface (1a). The support comprises a substrate (4) which is made of silicon or gallium arsenide. Moreover, the insulating layer (2) can be covered with a hydrophobic layer (3), preferably of fluorocarbon compounds or amorphous carbons, such as to form the hydrophobic surface (1a).

Description

Lentille à focale variable comprenant un substrat en silicium ou en arséniure de gallium.Variable focal length lens comprising a silicon or gallium arsenide substrate.
Domaine technique de l'inventionTechnical field of the invention
L'invention concerne une lentille à focale variable comprenant une couche électriquement isolante formée sur au moins une partie d'un support, des moyens de former sur la couche isolante une surface hydrophobe et une goutte d'un liquide électriquement isolant disposée sur la surface hydrophobe.The invention relates to a lens with variable focal length comprising an electrically insulating layer formed on at least part of a support, means for forming on the insulating layer a hydrophobic surface and a drop of an electrically insulating liquid arranged on the hydrophobic surface. .
État de la techniqueState of the art
Les lentilles à focale variable sont de plus en plus utilisées dans des dispositifs d'imagerie et notamment dans les caméras, les appareils photographiques ou les microscopes. Le principe consiste à immerger une micro-lentille constituée par une goutte d'un liquide électriquement isolant dans une cellule remplie d'un liquide organique conducteur et non miscible avec le liquide isolant. L'application d'une différence de potentiel à travers la cellule permet d'obtenir une lentille à focale variable, en faisant varier la forme de la goutte. A titre d'exemple, le document JP-A-2001013306 décrit un dispositif de lentille à focale variable comportant une cellule remplie d'un liquide conducteur. Une couche isolante est disposée sur la surface inférieure de la cellule. Une partie circulaire de la couche isolante est exposée de manière à venir en contact avec une goutte en liquide isolant tandis que la partie complémentaire de la couche isolante est recouverte par une couche de surface dont l'affinité avec la goutte en liquide isolant est inférieure à celle avec la couche isolante. Des moyens d'application d'une différence de potentiel permettent de modifier la forme de la goutte.Varifocal lenses are more and more used in imaging devices and in particular in cameras, photographic devices or microscopes. The principle consists in immersing a microlens consisting of a drop of an electrically insulating liquid in a cell filled with a conductive organic liquid and immiscible with the insulating liquid. The application of a potential difference across the cell makes it possible to obtain a lens with variable focal length, by varying the shape of the drop. By way of example, the document JP-A-2001013306 describes a variable focal lens device comprising a cell filled with a conductive liquid. An insulating layer is arranged on the lower surface of the cell. A circular part of the insulating layer is exposed so as to come into contact with a drop of insulating liquid while the complementary part of the insulating layer is covered by a surface layer whose affinity with the drop of insulating liquid is less than the one with the insulating layer. Means application of a potential difference make it possible to modify the shape of the drop.
Des moyens de centrage ont été proposés pour contrôler la forme de la goutte, une fois la tension appliquée. Ainsi, le document EP-A1 -1 166157 décrit un procédé de centrage consistant à former, à un emplacement donné d'une surface, un évidement évasé dans lequel est maintenue la goutte.Centering means have been proposed to control the shape of the drop, once the tension has been applied. Thus, document EP-A1-1 166157 describes a centering process consisting in forming, at a given location on a surface, a flared recess in which the drop is kept.
Les substrats connus pour réaliser de telles lentilles à focale variable, sont généralement en acier inoxydable, en alumine, en matériau plastique ou en verre. Une cavité, généralement de forme conique et destinée à centrer la goutte de liquide isolant, est réalisée dans le substrat. Une couche servant d'isolant électrique, en polymères fluorés tels que le Téflon® commercialisé par la société Tetrachim, est déposée sur ce substrat par thermocollage, puis elle est usinée pour obtenir une épaisseur de 2 microns environ. Ces substrats ne permettent, cependant, pas d'obtenir un bon aspect de surface, ni des formes reproductibles. En effet, l'usinage du Téflon® et la formation de la cavité, par exemple par électroérosion pour un substrat en acier inoxydable, génèrent une variation de l'épaisseur de la couche isolante et des rugosités de surface importantes dans le substrat.The known substrates for producing such lenses with variable focal length are generally made of stainless steel, alumina, plastic material or glass. A cavity, generally conical in shape and intended to center the drop of insulating liquid, is produced in the substrate. A layer serving as electrical insulator, made of fluoropolymers such as Teflon® sold by the company Tetrachim, is deposited on this substrate by heat-bonding, then it is machined to obtain a thickness of approximately 2 microns. These substrates do not, however, allow a good surface appearance or reproducible shapes to be obtained. Indeed, the machining of Teflon® and the formation of the cavity, for example by EDM for a stainless steel substrate, generate a variation in the thickness of the insulating layer and significant surface roughness in the substrate.
Objet de l'inventionSubject of the invention
L'invention a pour but une lentille à focale variable facile à réaliser et comportant un support ayant un aspect de surface satisfaisant et sur lequel peuvent être déposées des couches minces d'épaisseur contrôlée. Selon l'invention, ce but est atteint par le fait que le support est constitué par un substrat en silicium ou en arséniure de gallium.The object of the invention is to make a variable focal length lens easy to produce and comprising a support having a satisfactory surface appearance and on which thin layers of controlled thickness can be deposited. According to the invention, this object is achieved by the fact that the support consists of a silicon or gallium arsenide substrate.
Selon un développement de l'invention, le support comporte une cavité conique destinée à contenir la goutte.According to a development of the invention, the support comprises a conical cavity intended to contain the drop.
Selon une autre caractéristique de l'invention, le substrat en silicium ou en arséniure de gallium est recouvert par une couche conductrice électriquement.According to another characteristic of the invention, the silicon or gallium arsenide substrate is covered by an electrically conductive layer.
Selon une autre caractéristique, la couche conductrice est constituée par un matériau choisi parmi le groupe comprenant le silicium polycristallin, le tungstène, le platine, le cuivre, le titane, le cobalt, le tantale, le germanium, le molybdène, le ruthénium, les siliciures de tungstène, de titane, de cobalt ou de germanium et les nitrures de titane ou de tantale.According to another characteristic, the conductive layer consists of a material chosen from the group comprising polycrystalline silicon, tungsten, platinum, copper, titanium, cobalt, tantalum, germanium, molybdenum, ruthenium, silicides of tungsten, titanium, cobalt or germanium and nitrides of titanium or tantalum.
Selon un mode de réalisation préférentiel, la couche isolante est constituée par un matériau diélectrique ayant une permittivité supérieure à 3,9.According to a preferred embodiment, the insulating layer consists of a dielectric material having a permittivity greater than 3.9.
Description sommaire des dessinsBrief description of the drawings
D'autres avantages et caractéristiques ressortiront plus clairement de la description qui va suivre de modes particuliers de réalisation de l'invention donnés à titre d'exemples non limitatifs et représentés aux dessins annexés, dans lesquels :Other advantages and characteristics will emerge more clearly from the description which follows of particular embodiments of the invention given by way of nonlimiting examples and represented in the appended drawings, in which:
La figure 1 est une vue en coupe d'un premier mode de réalisation d'une partie d'une lentille à focale variable selon l'invention. La figure 2 est une vue en coupe d'un second mode de réalisation d'une partie d'une lentille selon l'invention.Figure 1 is a sectional view of a first embodiment of a part of a variable focal lens according to the invention. Figure 2 is a sectional view of a second embodiment of part of a lens according to the invention.
La figure 3 est une vue en coupe d'un troisième mode de réalisation d'une partie d'une lentille selon l'invention.Figure 3 is a sectional view of a third embodiment of part of a lens according to the invention.
Description de modes particuliers de réalisation.Description of particular embodiments.
Une lentille à focale variable, selon l'invention, comporte une couche électriquement isolante formée sur au moins une partie d'un support, des moyens de former sur la couche isolante une surface hydrophobe et une goutte d'un liquide électriquement isolant disposée sur la surface hydrophobe. Le support est constitué par un substrat en silicium ou en arséniure de gallium.A variable focal length lens according to the invention comprises an electrically insulating layer formed on at least part of a support, means for forming on the insulating layer a hydrophobic surface and a drop of an electrically insulating liquid disposed on the hydrophobic surface. The support consists of a silicon or gallium arsenide substrate.
Selon un premier mode de réalisation représenté à la figure 1 , une goutte 1 d'un liquide électriquement isolant est disposée sur une surface hydrophobe 1 a d'une couche électriquement isolante 2, de préférence dans une enceinte remplie par un liquide conducteur (non représentés). La goutte 1 correspond à une microlentille dont la focale peut varier continûment en utilisant le phénomène d'électromouillage. Ainsi, la mouillabilité de la goutte 1 augmente sensiblement en présence d'un champ électrique dû à une tension électrique appliquée entre une première électrode disposée sous la goutte 1 et une seconde électrode ou le liquide conducteur. Les deux liquides respectivement isolant et conducteur sont transparents, non miscibles, et ils ont des indices de réfraction différents. La surface hydrophobe 1a présente une faible mouillabilité vis-à-vis du liquide conducteur et une forte mouillabilité vis-à-vis du liquide isolant.According to a first embodiment shown in FIG. 1, a drop 1 of an electrically insulating liquid is placed on a hydrophobic surface 1 a of an electrically insulating layer 2, preferably in an enclosure filled with a conductive liquid (not shown ). The drop 1 corresponds to a microlens whose focal length can vary continuously using the electrowetting phenomenon. Thus, the wettability of the drop 1 increases appreciably in the presence of an electric field due to an electric voltage applied between a first electrode disposed under the drop 1 and a second electrode or the conductive liquid. The two respectively insulating and conducting liquids are transparent, immiscible, and they have different refractive indices. The hydrophobic surface 1a has a low wettability vis-à-vis the conductive liquid and a high wettability vis-à-vis the insulating liquid.
La couche isolante 2 est, de préférence, en oxyde de silicium dopé avec du carbone (SiOCH) ou en composés carbofluorés (CFX avec x compris entre 1 et 4), de manière à rendre sa surface hydrophobe. La couche isolante 2 est disposée sur au moins une partie d'un support destiné à former la première électrode permettant d'appliquer une tension électrique avec le liquide conducteur. Le support est constitué par un substrat 4 en silicium ou en arséniure de gallium, ledit substrat ayant, de préférence, une épaisseur inférieure à 1 mm. La conductivité électrique du substrat 4 en silicium ou en arséniure de gallium peut être renforcée par une couche électriquement conductrice le recouvrant ou bien par dopage. Le dopage du support évite ainsi le dépôt d'une couche mince supplémentaire électriquement conductrice et il permet éventuellement de fabriquer de manière intrinsèque, dans le support, la première électrode.The insulating layer 2 is preferably made of silicon oxide doped with carbon (SiOCH) or of carbofluorinated compounds (CF X with x between 1 and 4), so as to make its surface hydrophobic. The insulating layer 2 is arranged on at least part of a support intended to form the first electrode making it possible to apply an electrical voltage with the conductive liquid. The support consists of a substrate 4 made of silicon or gallium arsenide, said substrate preferably having a thickness of less than 1 mm. The electrical conductivity of the substrate 4 made of silicon or gallium arsenide can be reinforced by an electrically conductive layer covering it or else by doping. The doping of the support thus prevents the deposition of an additional electrically conductive thin layer and it optionally allows the first electrode to be produced intrinsically in the support.
Dans un second mode de réalisation représenté à la figure 2, le support est constitué par un substrat 4 en silicium ou en arséniure de gallium recouvert par une couche électriquement conductrice 5. La couche électriquement conductriceIn a second embodiment shown in FIG. 2, the support consists of a substrate 4 of silicon or of gallium arsenide covered by an electrically conductive layer 5. The electrically conductive layer
5 est, de préférence, constituée par un matériau choisi parmi le groupe comprenant le silicium polycristallin, le tungstène, le platine, le cuivre, le titane, le cobalt, le tantale, le germanium, le molybdène, le ruthénium, les siliciures de tungstène, de titane, de cobalt ou de germanium et les nitrures de titane ou de tantale. La couche électriquement conductrice 5 a, de préférence, une épaisseur comprise entre 50nm et 1000nm tandis que le substrat 4 a, de préférence, une épaisseur inférieure à 1 mm.5 is preferably made of a material chosen from the group comprising polycrystalline silicon, tungsten, platinum, copper, titanium, cobalt, tantalum, germanium, molybdenum, ruthenium, tungsten silicides , titanium, cobalt or germanium and nitrides of titanium or tantalum. The electrically conductive layer 5 preferably has a thickness of between 50 nm and 1000 nm while the substrate 4 preferably has a thickness of less than 1 mm.
Une couche isolante 2 est disposée sur la couche électriquement conductrice 5 du support. Elle a, de préférence, une épaisseur inférieure ou égale à 2 micromètres et elle est, de préférence, constituée par un matériau diélectrique ayant une permittivité supérieure à 3,9. Le matériau diélectrique est, par exemple, choisi parmi le groupe comprenant le nitrure de silicium, un silicium amorphe dopé avec du carbone, un silicium amorphe dopé avec du carbone et de l'azote, les oxydes de silicium, de tantale, de titane, de hafnium, de zirconium, l'alumine, l'oxyde de titane et de strontium, l'oxyde de titane et de baryum, l'oxyde de titane, de zirconium et de plomb, plus connu sous le nom de PZT, et l'oxyde de titane, de baryum et de strontium, connu également sous le nom de SBT. Une couche hydrophobe 3 est disposée sur la couche isolante 2 de manière à former la surface hydrophobe 1 a qui est, de préférence, en composés carbofluorés, c'est-à-dire en CFx, avec x compris entre 1 et 4, ou en carbones amorphes, c'est-à-dire CHx, avec x compris entre 1 et 4. La couche hydrophobe 3 permet d'obtenir un angle de goutte supérieur à 90°, pouvant même atteindre 140°.An insulating layer 2 is disposed on the electrically conductive layer 5 of the support. It preferably has a thickness less than or equal to 2 micrometers and it is preferably made of a dielectric material having a permittivity greater than 3.9. The dielectric material is, for example, chosen from the group comprising silicon nitride, an amorphous silicon doped with carbon, an amorphous silicon doped with carbon and nitrogen, oxides of silicon, tantalum, titanium, hafnium, zirconium, alumina, titanium oxide and strontium, titanium oxide and barium, titanium oxide, zirconium and lead, better known as PZT, and titanium oxide, barium and strontium, also known as SBT. A hydrophobic layer 3 is disposed on the insulating layer 2 so as to form the hydrophobic surface 1 a which is preferably made of carbofluorinated compounds, that is to say in CFx, with x between 1 and 4, or in amorphous carbons, that is to say CHx, with x comprised between 1 and 4. The hydrophobic layer 3 makes it possible to obtain a drop angle greater than 90 °, possibly even reaching 140 °.
Le fait que la couche isolante 2 ait une permittivité supérieure à 3,9 permet, notamment, de diminuer la tension électrique appliquée sur la goutte 1 d'un facteur 100 par rapport à une couche isolante selon l'art antérieur et plus particulièrement par rapport à une couche isolante en Téflon®.The fact that the insulating layer 2 has a permittivity greater than 3.9 makes it possible, in particular, to reduce the electric voltage applied to the drop 1 by a factor of 100 compared to an insulating layer according to the prior art and more particularly compared with an insulating layer of Teflon®.
L'utilisation d'un substrat 4 en silicium ou en arséniure de gallium présente l'avantage de pouvoir utiliser les techniques de la microélectronique, en particulier les méthodes de dépôt de couches minces et de gravure. En effet, le silicium et l'arséniure de gallium présentent des plans de clivage qui permettent de conserver une rugosité de surface très faible, ce qui facilite des dépôts de couches minces à épaisseur contrôlée et des gravures de meilleure qualité. Ainsi le dépôt de la couche électriquement conductrice 5 sur le substrat 4 (figure 2) peut être réalisé par un dépôt en phase vapeur de type PVD, CVD, PECVD ou MOCVD, respectivement connus sous le nom anglo-saxon de «PhysicalThe use of a substrate 4 of silicon or of gallium arsenide has the advantage of being able to use the techniques of microelectronics, in particular the methods of depositing thin layers and of etching. Indeed, silicon and gallium arsenide have cleavage planes which allow to maintain a very low surface roughness, which facilitates deposits of thin layers with controlled thickness and better quality etchings. Thus, the deposition of the electrically conductive layer 5 on the substrate 4 (FIG. 2) can be carried out by a vapor phase deposition of the PVD, CVD, PECVD or MOCVD type, respectively known by the English name of "Physical
Vapor Déposition », «Chemical Vapor Déposition », Plasma Enhanced Chemical Vapor Desposition », et Metal-Organic Chemical Vapor Déposition ». Ceci permet de réaliser des dépôts dont l'épaisseur varie de moins de 2% sur un diamètre de 200mm. L'uniformité de l'épaisseur du dépôt permet ainsi d'obtenir un support ayant une conductivité électrique stable.Vapor Deposition "," Chemical Vapor Deposition ", Plasma Enhanced Chemical Vapor Desposition", and Metal-Organic Chemical Vapor Deposition ". This allows deposits to be made whose thickness varies by less than 2% over a diameter of 200mm. The uniformity of the thickness of the deposit thus makes it possible to obtain a support having a stable electrical conductivity.
Selon une variante de réalisation représentée à la figure 3, le substrat 4 comporte une cavité conique 6 dans laquelle est disposée la goutte 1 . La cavité conique 6 permet de maintenir la goutte 1 à un emplacement donné du support. La pente de la cavité 6 est, de préférence, déterminée selon un procédé de centrage décrit dans le document WO-A1 -0058763. Le fait d'utiliser un substrat en silicium ou en arséniure de gallium permet de former la cavité 6, grâce à un procédé issu de la microélectronique, telle que la gravure par plasma. A titre d'exemple, un dépôt de résine et une photolithographie de 365 nm sont réalisés sur un substrat 4 en silicium, de manière à réaliser la cavité conique 6 par une gravure sèche par bromure et chlore (HBr et Cl2) ou par hexafluorure de soufre (SF6), dans un réacteur plasma à haute ou moyenne densité, de type plasma par couplage inductif (Inductive Coupling Plasma ou ICP), gravure ioniqueAccording to an alternative embodiment shown in FIG. 3, the substrate 4 comprises a conical cavity 6 in which the drop 1 is arranged. The conical cavity 6 keeps the drop 1 at a given location on the support. The slope of the cavity 6 is preferably determined according to a centering method described in the document WO-A1 -0058763. The fact of using a silicon or gallium arsenide substrate makes it possible to form the cavity 6, by virtue of a process resulting from microelectronics, such as plasma etching. By way of example, a resin deposit and a photolithography of 365 nm are carried out on a silicon substrate 4, so as to produce the conical cavity 6 by dry etching with bromide and chlorine (HBr and Cl 2 ) or with hexafluoride of sulfur (SF 6 ), in a high or medium density plasma reactor, of the plasma type by inductive coupling (Inductive Coupling Plasma or ICP), ion etching
(Reactive Ion Etchning ou RIE) ou Electro-Cylco-Résonance (ECR), RIE, ECR, ou ICP. La polymérisation de la résine est contrôlée de sorte que la pente de cavité 6 est de 45°. Une couche électriquement conductrice 5 de 50 nm peut être déposée sur le substrat 4 pour renforcer sa conductibilité puis la couche électriquement isolante 2, d'une épaisseur de 2 microns et la couche hydrophobe 3 sont successivement déposées sur le substrat 4.(Reactive Ion Etchning or RIE) or Electro-Cylco-Resonance (ECR), RIE, ECR, or ICP. The polymerization of the resin is controlled so that the cavity slope 6 is 45 °. An electrically conductive layer 5 of 50 nm can be deposited on the substrate 4 to reinforce its conductivity, then the electrically insulating layer 2, with a thickness of 2 microns and the hydrophobic layer 3 are successively deposited on the substrate 4.
Ainsi, cette technique de gravure sur un substrat, par exemple en silicium, permet de contrôler très précisément la pente du cône de la cavité 6, à ± 1 °, tout en engendrant une faible rugosité de surface. La rugosité est, de préférence, inférieure à 50nm. De plus, la couche isolante 2 est déposée de manière uniforme à l'intérieur du cône. Un substrat en silicium permet également de simplifier le procédé de fabrication d'une lentille à focale variable, de réduire les coûts de fabrication et d'assurer une production reproductible de lentilles à focale variable. Une lentille à focale variable selon l'invention peut, par exemple, être utilisée dans des caméras, des appareils photographiques, des microscope. Thus, this etching technique on a substrate, for example made of silicon, makes it possible to very precisely control the slope of the cone of the cavity 6, within ± 1 °, while generating a low surface roughness. The roughness is preferably less than 50nm. In addition, the insulating layer 2 is deposited uniformly inside the cone. A silicon substrate also makes it possible to simplify the method of manufacturing a lens with variable focal length, to reduce the manufacturing costs and to ensure a reproducible production of lenses with variable focal length. A variable focal lens according to the invention can, for example, be used in cameras, photographic cameras, microscopes.

Claims

Revendications claims
1. Lentille à focale variable comprenant une couche électriquement isolante (2) formée sur au moins une partie d'un support, des moyens de former sur la couche isolante une surface hydrophobe (1 a) et une goutte (1) d'un liquide électriquement isolant disposée sur la surface hydrophobe, lentille caractérisée en ce que le support est constitué par un substrat (4) en silicium ou en arséniure de gallium.1. Lens with variable focal length comprising an electrically insulating layer (2) formed on at least part of a support, means for forming on the insulating layer a hydrophobic surface (1 a) and a drop (1) of a liquid electrically insulating disposed on the hydrophobic surface, lens characterized in that the support consists of a substrate (4) of silicon or gallium arsenide.
2. Lentille selon la revendication 1 , caractérisée en ce que le support comporte une cavité (6) conique destinée à contenir la goutte.2. Lens according to claim 1, characterized in that the support comprises a conical cavity (6) intended to contain the drop.
3. Lentille selon l'une des revendications 1 et 2, caractérisée en ce que le substrat (4) a une épaisseur inférieure à 1 mm.3. Lens according to one of claims 1 and 2, characterized in that the substrate (4) has a thickness less than 1 mm.
4. Lentille selon l'une quelconque des revendications 1 à 3, caractérisée en ce que le substrat (4) en silicium ou en arséniure de gallium est recouvert par une couche conductrice (5) électriquement.4. Lens according to any one of claims 1 to 3, characterized in that the substrate (4) of silicon or gallium arsenide is covered by an electrically conductive layer (5).
5. Lentille selon la revendication 4, caractérisée en ce que la couche conductrice (5) est constituée par un matériau choisi parmi le groupe comprenant le silicium polycristallin, le tungstène, le platine, le cuivre, le titane, le cobalt, le tantale, le germanium, le molybdène, le ruthénium, les siliciures de tungstène, de titane, de cobalt ou de germanium et les nitrures de titane ou de tantale.5. Lens according to claim 4, characterized in that the conductive layer (5) consists of a material chosen from the group comprising polycrystalline silicon, tungsten, platinum, copper, titanium, cobalt, tantalum, germanium, molybdenum, ruthenium, silicas of tungsten, titanium, cobalt or germanium and nitrides of titanium or tantalum.
6. Lentille selon l'une des revendications 4 et 5, caractérisée en ce que la couche conductrice (5) a une épaisseur comprise entre 50 et 1000nm. 6. Lens according to one of claims 4 and 5, characterized in that the conductive layer (5) has a thickness between 50 and 1000nm.
7. Lentille selon l'une quelconque des revendications 1 à 6, caractérisée en ce que la couche isolante (2) a une épaisseur inférieure ou égale à 2 micromètres.7. Lens according to any one of claims 1 to 6, characterized in that the insulating layer (2) has a thickness less than or equal to 2 micrometers.
8. Lentille selon l'une quelconque des revendications 1 à 7, caractérisée en ce que la couche isolante (2) est constituée par un matériau diélectrique ayant une permittivité supérieure à 3,9.8. Lens according to any one of claims 1 to 7, characterized in that the insulating layer (2) consists of a dielectric material having a permittivity greater than 3.9.
9. Lentille selon la revendication 8, caractérisée en ce que le matériau diélectrique est choisi parmi le groupe comprenant le nitrure de silicium, un silicium amorphe dopé avec du carbone, un silicium amorphe dopé avec du carbone et de l'azote, les oxydes de silicium, de tantale, de titane, de hafnium, de zirconium, l'alumine, l'oxyde de titane et de strontium, l'oxyde de titane et de baryum, l'oxyde de titane, de zirconium et de plomb, et l'oxyde de titane, de baryum et de strontium.9. Lens according to claim 8, characterized in that the dielectric material is chosen from the group comprising silicon nitride, an amorphous silicon doped with carbon, an amorphous silicon doped with carbon and nitrogen, the oxides of silicon, tantalum, titanium, hafnium, zirconium, alumina, titanium oxide and strontium, titanium oxide and barium, titanium oxide, zirconium and lead, and l of titanium, barium and strontium.
10. Lentille selon l'une quelconque des revendications 1 à 9, caractérisée en ce qu'une couche hydrophobe (3) est disposée sur la couche isolante (2) de manière à former la surface hydrophobe (1a).10. Lens according to any one of claims 1 to 9, characterized in that a hydrophobic layer (3) is disposed on the insulating layer (2) so as to form the hydrophobic surface (1a).
11. Lentille selon la revendication 10, caractérisée en ce que la couche hydrophobe (3) est en composés carbofluorés ou en carbones amorphes.11. Lens according to claim 10, characterized in that the hydrophobic layer (3) is made of carbofluorinated compounds or amorphous carbons.
12. Lentille selon l'une quelconque des revendications 1 à 6, caractérisée en ce que la couche isolante (2) est en oxyde de silicium dopé avec du carbone ou en composés carbofluorés, de manière à rendre sa surface (1a) hydrophobe. 12. Lens according to any one of claims 1 to 6, characterized in that the insulating layer (2) is made of silicon oxide doped with carbon or of carbofluorinated compounds, so as to make its surface (1a) hydrophobic.
PCT/FR2004/000286 2003-02-12 2004-02-09 Variable-focus lens comprising a silicon or gallium arsenide substrate WO2004074902A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0301687A FR2851052B1 (en) 2003-02-12 2003-02-12 VARIABLE FOCAL LENS COMPRISING A SILICON, GALLIUM OR QUARTZ ARSENIURE SUBSTRATE
FR03/01687 2003-02-12

Publications (1)

Publication Number Publication Date
WO2004074902A1 true WO2004074902A1 (en) 2004-09-02

Family

ID=32731985

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FR2004/000286 WO2004074902A1 (en) 2003-02-12 2004-02-09 Variable-focus lens comprising a silicon or gallium arsenide substrate

Country Status (2)

Country Link
FR (1) FR2851052B1 (en)
WO (1) WO2004074902A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2880135B1 (en) * 2004-12-23 2007-03-16 Varioptic Sa VARIABLE FOCAL LENS WITH WIDE RANGE OF VARIATION
DE102005025722A1 (en) * 2005-06-04 2006-07-13 Landesstiftung Baden-Württemberg gGmbH Optical lens with electrically variable focal length, has lens body formed substrate made of silicon or silicon material

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3670130A (en) * 1969-03-07 1972-06-13 Int Standard Electric Corp Improvements in electrostatic relays
US4030813A (en) * 1974-12-20 1977-06-21 Matsushita Electric Industrial Co., Ltd. Control element having liquid layer attainable to geometrically uneven state in response to electrical signal
WO2000058763A1 (en) * 1999-03-26 2000-10-05 Universite Joseph Fourier Drop centering device
JP2001013306A (en) * 1999-06-28 2001-01-19 Canon Inc Variable focus lens device
US20020154380A1 (en) * 2001-04-19 2002-10-24 Daniel Gelbart Method for controlling light beam using adaptive micro-lens

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2769375B1 (en) * 1997-10-08 2001-01-19 Univ Joseph Fourier VARIABLE FOCAL LENS
JP2000347005A (en) * 1999-06-02 2000-12-15 Canon Inc Variable-focus lens device
US6449081B1 (en) * 1999-06-16 2002-09-10 Canon Kabushiki Kaisha Optical element and optical device having it
US6538823B2 (en) * 2001-06-19 2003-03-25 Lucent Technologies Inc. Tunable liquid microlens

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3670130A (en) * 1969-03-07 1972-06-13 Int Standard Electric Corp Improvements in electrostatic relays
US4030813A (en) * 1974-12-20 1977-06-21 Matsushita Electric Industrial Co., Ltd. Control element having liquid layer attainable to geometrically uneven state in response to electrical signal
WO2000058763A1 (en) * 1999-03-26 2000-10-05 Universite Joseph Fourier Drop centering device
EP1166157A1 (en) * 1999-03-26 2002-01-02 Universite Joseph Fourier Drop centering device
JP2001013306A (en) * 1999-06-28 2001-01-19 Canon Inc Variable focus lens device
US20020154380A1 (en) * 2001-04-19 2002-10-24 Daniel Gelbart Method for controlling light beam using adaptive micro-lens

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
KRUPENKIN T ET AL: "TUNABLE LIQUID MICROLENS", APPLIED PHYSICS LETTERS, AMERICAN INSTITUTE OF PHYSICS. NEW YORK, US, vol. 82, no. 3, 20 January 2003 (2003-01-20), pages 316 - 318, XP001159542, ISSN: 0003-6951 *
PATENT ABSTRACTS OF JAPAN vol. 2000, no. 16 8 May 2001 (2001-05-08) *
SUNGHOON KWON ET AL: "FOCAL LENGTH CONTROL BY MICROFABRICATED PLANAR ELECTRODES-BASED LIQUID LENS (MUPELL)", TRANSDUCERS '01 EUROSENSORS XV. 11TH INTERNATIONAL CONFERENCE ON SOLID-STATE SENSORS AND ACTUATORS. DIGEST OF TECHNICAL PAPERS. MUNICH, JUNE 10 - 14, 2001, INTERNATIONAL CONFERENCE ON SOLID-STATE SENSORS AND ACTUATORS. DIGEST OF TECHNICAL PAPERS, BER, vol. 2, 10 June 2001 (2001-06-10), pages 1348 - 1351, XP001153345, ISBN: 3-540-42150-5 *
WASHIZU M: "ELECTROSTATIC ACTUATION OF LIQUID DROPLETS FOR MICROREACTOR APPLICATIONS", IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, IEEE INC. NEW YORK, US, vol. 34, no. 4, July 1998 (1998-07-01), pages 732 - 737, XP000848012, ISSN: 0093-9994 *

Also Published As

Publication number Publication date
FR2851052A1 (en) 2004-08-13
FR2851052B1 (en) 2005-05-27

Similar Documents

Publication Publication Date Title
EP2203939B1 (en) Optoelectronic device including nanowires, and corresponding methods
EP2044474B1 (en) Optical filter matrix structure and associated image sensor
EP1801897A1 (en) Improved method of producing PMC type memory cells
LU84413A1 (en) CAPACITIVE PRESSURE TRANSDUCER WITH ELECTROSTATICALLY LINKED SILICON
EP0511096A1 (en) Process for local passivation of a substrate, by an hydrogenated amorphous carbon layer, and method for fabricating thin film transistors on this passivated substrate
EP2681776B1 (en) Method for metallizing textured surfaces
FR2907916A1 (en) Guide slot forming method for e.g. intra-optical connections of silicon chip, involves filling trenches with silicon, and carrying out annealing of silicon oxide layer after performing formation, graving or filling steps
EP0214033B1 (en) Process for making a light image sensor, and linear image sensor made by this process
FR2579775A1 (en) METHOD FOR PRODUCING NON-LINEAR CONTROL ELEMENTS FOR ELECTRO-OPTICAL VISUALIZATION DISPLAY SCREEN AND FLAT SCREEN CARRIED OUT ACCORDING TO THIS METHOD
EP2294464A1 (en) Micro/nanostructured optical waveguiding structure for monitoring birefringence
EP3000137B1 (en) Method for producing a photosensitive device
EP2599105A1 (en) Method for producing a capacitor including an array of nanocapacitors
EP2591506B1 (en) Method of forming a microelectronic device having metal interconnection levels connected by programmable vias
WO2019202250A1 (en) Optoelectronic device having a diode put under tensile stress by an inverse piezoelectric effect
WO2004074902A1 (en) Variable-focus lens comprising a silicon or gallium arsenide substrate
FR2759491A1 (en) Cold cathode
EP1836526A1 (en) Capacitive junction modulator, capacitive junction and method for making same
EP3968397B1 (en) Piezoelectric device with elongate piezoelectric nano-objects
FR2970812A1 (en) FIELD EFFECT DEVICE WITH LOW JUNCTION CAPACITY
EP3594997A1 (en) Method for manufacturing at least one semiconductor structure comprising a step of separation from the growth substrate
FR2634064A1 (en) Electronic component with layer of high thermal conductivity
EP4148919B1 (en) Method for manufacturing a semiconductor diode by dry and wet etching
FR2932013A1 (en) Manufacturing photovoltaic cells having nanowires, comprises uniformly depositing sub-layer of semi-conductor material, forming a nanowire having the same type of doping on a sub-layer, and forming emitter layer on sub-layer
EP1557665A1 (en) Electrode system for an electrochemical sensor
EP4136681A1 (en) Method for manufacturing a device for emitting radiation

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): BW GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase