Electrochemically actuatable electronic component and process for producing the actuatable electronic component

Abstract

An electrochemically actuatable electronic component comprises: a substrate; at least one first and one second actuating electrodes; at least one first and one second measuring electrodes; at least one storing electrode configured to free ions under the action of the actuating electrodes; at least one ionic conductor able to conduct the ions and that is located in a region placed between the measuring electrodes; a device suitable for: applying a voltage or a current between the first and second actuating electrodes to allow the migration of ions from the storing electrode to the first actuating electrode forming thereon an electrochemical deposition through the ionic conductor and for measuring, between the first and second measuring electrodes, a modification of at least one characteristic of the region placed between the first and second measuring electrodes, to determine at least one characteristic of the electronic component.

Claims

1. An electrochemically actuatable electronic component comprising: a substrate; at least one first and one second actuating electrodes; at least one first and one second measuring electrodes that are electrically independent from the first and second actuating electrodes; at least one storing electrode configured to free ions under the action of the actuating electrodes; at least one ionic conductor that is able to conduct said ions and that is located in a region placed between said measuring electrodes; said measuring electrodes being configured to measure at least one characteristic of said region placed between the first and second measuring electrodes; a device suitable for: applying a voltage or a current between the first and second actuating electrodes in order to allow either the migration of ions from the storing electrode to the first actuating electrode forming thereon an electrochemical deposition through the ionic conductor or the at least partial dissolution of the electrochemical deposition and for measuring, between the first and second measuring electrodes, a modification of at least one characteristic of the region placed between the first and second measuring electrodes, induced by the formation of the electrochemical deposition or by the at least partial dissolution thereof, so as to determine at least one characteristic of said electronic component.

2. The electronic component according to claim 1, wherein the ionic conductor makes contact with the storing electrode and with said first actuating electrode.

3. The electronic component according to claim 1, wherein at least said first actuating electrode is made of a material unable to form a compound with said ions.

4. The electronic component, according to claim 1, wherein the storing electrode makes contact with said second actuating electrode.

5. The electronic component according to claim 1, further comprising an electrode that is insertionally saturatable with said ions making contact with said ionic conductor and contact with said first actuating electrode.

6. The electronic component according to claim 5, wherein the storing electrode is an electrode for storing Li or Ag or Cu or Na or Mg or Al or Ca metal ions, and wherein the electrode for inserting ions is made of Si or Ge or Al, the storing electrode including Li ions.

7. The electronic component according to claim 1, wherein the actuating electrodes are positioned one with respect to the other parallelly to the substrate so as to ensure the formation of an electrodeposit in a plane orthogonal to said substrate, the measuring electrodes being positioned one with respect to the other orthogonally to the substrate.

8. The electronic component according to claim 1, wherein the actuating electrodes are positioned one with respect to the other orthogonally to the substrate so as to ensure the formation of an electrodeposit in a plane parallel to said substrate, the measuring electrodes being positioned one with respect to the other parallelly to the substrate.

9. The electronic component according to claim 1, further comprising at least one third measuring electrode and one fourth measuring electrode that are separated by said storing electrode so as to modulate the insertion and deinsertion of ions into/from said storing electrode and to measure a modification of at least one characteristic of the storing electrode.

10. The electronic component according to claim 1, further comprising an internal first passivating dielectric and/or an external second passivating dielectric, wherein any of the internal first passivating dielectric and the external second passivating dielectric comprises SiO.sub.2 or Si.sub.3N.sub.4 or Al.sub.2O.sub.3.

11. The electronic component according to claim 1, wherein the storing electrode is an electrode for storing Li or Ag or Cu or Na or Mg or Al or Ca metal ions.

12. The electronic component according to claim 11, wherein the storing electrode is made of LiCoO.sub.2.

13. The electronic component according to claim 1, wherein the storing electrode consists of a metal allowing metal ions to be freed under the action of the actuating electrodes.

14. The electronic component according to claim 1 wherein, the ionic conductor is a lithium phosphorous nitride.

15. The electronic component according to claim 1, wherein one or both of the actuating electrodes is (are) made of Cu or Pt.

16. The electronic component according to claim 1, wherein one or both of the measuring electrodes is (are) made of Ni or Cu or Mo or W or Pt or ITO conductive oxide.

17. A process for manufacturing a component according to claim 1, including the following steps: depositing and structuring at least one actuating electrode on the surface of a substrate; depositing and structuring at least one measuring electrode on the surface of said substrate; depositing and structuring a storing electrode; depositing and structuring an ionic conductor; depositing and structuring an internal passivating dielectric.

18. The process for manufacturing a tuneable component according to claim 17, wherein the storing electrode is deposited by reactive sputtering of a target, the structuring being carried out by photolithography and plasma etching.

19. The process for manufacturing a tuneable component according to claim 17, wherein the ionic conductor is deposited by reactive sputtering, the structuring being carried out by photolithography and plasma etching.

20. An assembly, including on a substrate a plurality of elementary blocks, each elementary block being independently controllable and comprising: at least one first and one second actuating electrodes; at least one first and one second measuring electrodes that are electrically independent from the first and second actuating electrodes; at least one storing electrode configured to free ions; at least one ionic conductor that is able to conduct said ions and that is located in a region placed between said measuring electrodes; said measuring electrodes being configured to measure at least one characteristic of said region placed between the first and second measuring electrodes, said assembly comprising a device suitable for: applying in each block, a voltage or a current between the first and second actuating electrodes in order to allow either the migration of ions from the storing electrode to the first actuating electrode forming thereon an electrochemical deposition through the ionic conductor or the at least partial dissolution of the electrochemical deposition and for measuring in each elementary block, between the first and second measuring electrodes, a modification of at least one characteristic of the region placed between the first and a second measuring electrodes, induced by the formation of the electrochemical deposition or by the at least partial dissolution thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood and other advantages will become apparent on reading the following nonlimiting description, which is given with reference to the appended figures, in which:

(2) FIG. 1 illustrates the variation in the thermal conductivity of an Li.sub.xCoO.sub.2 material as a function of the degree of insertion of lithium x, according to the prior art;

(3) FIG. 2 illustrates the variation in the electronic conductivity caused by creating a Cu filament through a Cu ionic conductor according to the prior art;

(4) FIGS. 3a and 3b schematically show in cross section a first exemplary component of the invention without actuating voltage and in the presence of an actuating voltage;

(5) FIGS. 4a and 4b illustrate top views of a tuneable component according to the invention (for the component in the state without and with electrodeposit in the intermediate zone between the measuring electrodes, respectively);

(6) FIGS. 5a and 5b illustrate a variant of the invention in which the tuneable electronic component furthermore includes an additional electrode called an insertion electrode that is saturatable with the ion (for the component in the state without and with electrodeposit in the intermediate zone between the measuring electrodes, respectively);

(7) FIGS. 6a and 6b illustrate a variant of the invention in which the tuneable electronic component takes advantage of the possible variation associated with the insertion/deinsertion into/from the storing electrode with the addition of a pair of electrodes separated by the storing electrode (for the component in the state without and with electrodeposit in the intermediate zone between the measuring electrodes, respectively);

(8) FIGS. 7a and 7b illustrate a variant of the invention in which the tuneable electronic component has a configuration allowing the formation of the electrodeposit in a plane parallel to the substrate (for the component in the state without and with electrodeposit in the intermediate zone between the measuring electrodes, respectively);

(9) FIGS. 8a and 8b illustrate an assembly of tuneable electronic functions according to the invention (for the component in the state without and with electrodeposit in the intermediate zone between the measuring electrodes, respectively).

DETAILED DESCRIPTION

(10) Generally, the subject of the present invention is an electronic component that is tuneable via a new electrochemical actuating mode based on electrodeposition of a metallic layer.

(11) FIG. 3a schematically illustrates in cross section an exemplary component architecture according to the invention. The component comprises a first pair of actuating electrodes 11 and 12, a second pair of measuring electrodes 21 and 22, an electrode 3 for storing ions, an ionic conductor 4 and passivating layers 5 and 6, all of which are deposited on a substrate 7.

(12) The operating principle of such a tuneable component is explained below.

(13) The application of a voltage U.sub.actuation between the electrodes 11 and 12 (actuating electrodes) for a time t.sub.actuation leads to the migration of ions from the electrode 3 for storing ions through the ionic conductor 4, the ions then accumulating on the surface of the electrode 11 in the form of a continuous deposit. The electrodeposition layer 8 is thus formed in at least one portion of the zone located between the two electrodes 21 and 22 (measuring electrodes), as shown in FIG. 3b. The presence of the electrodeposit induces a modification of at least one of the characteristics of the zone between the measuring electrodes 21 and 22. This characteristic may for example be an electronic conductivity, a permittivity, a thermal conductivity, a refractive index, etc.

(14) The response of the component between the two measuring electrodes 21 and 22 is thus modified because of the modification of the characteristic of the zone between the measuring electrodes 21 and 22, which is associated with the formation of the electrodeposit. The actuating electrodes 11-12 and measuring electrodes 21-22 are separate, contrary to the case of actuation by filament formation.

(15) The application of a voltage U.sub.actuation between the electrodes 11 and 12 leads to the migration of ions in the opposite direction to above, i.e. from the zone of electrodeposition on the surface of the electrode 11 to the storing electrode, and to the insertion therein once more. This operation induces a variation in the response of the component in the opposite direction to the variation induced by the application of the voltage U.sub.actuation.

(16) The tuneable component such as described has a plurality of possible states of variation in its response:

(17) a state without electrodeposit between the electrodes 21 and 22: the response of the component is directly related to the characteristics of the ionic conductor, present alone in the intermediate zone 21/22;

(18) a state with a complete electrodeposit between the electrodes 21 and 22: in this state all the ions initially present in the storing electrode 3 have migrated to the electrode 11 and formed an electrodeposit thereon;

(19) states with intermediate electrodeposits: in these various states some of the ions initially present in the storing electrode 3 have migrated to the electrode 11 and formed an electrodeposit thereon.

(20) FIGS. 4a and 4b illustrate top views of a tuneable component according to the invention (FIG. 4a and FIG. 4b: for the component in the state without and with electrodeposit in the intermediate zone 21/22, respectively). FIG. 4b shows the presence of the electrodeposit, which is characterized by a width denoted x. This width x varies depending on the actuation conditions of the component; more particularly, this width x is directly correlated to the time t.sub.actuation of application of the voltage U.sub.actuation. The variation in this width x allows the properties of the intermediate zone 21/22 to be changed and therefore intermediate responses (between that without electrodeposit and that with a complete electrodeposit) to be obtained from the tuneable component. It will be noted that the width x extends from the edge of the electrode 11 to a limit that is necessarily beyond the edge of the electrode 22 (FIG. 4b); in other words, the thickness of the electrodeposit (equal to the width x) is necessarily larger than the distance between the electrodes 11 and 21 in FIG. 4b.

(21) According to one particular operating mode, the application of a current I.sub.actuation (instead of a voltage as above) between the electrodes 11 and 12 for a time t.sub.actuation is used to make the ions migrate to the electrode 11 (formation of the electrodeposit), and a current I.sub.actuation is applied for a time t.sub.actuation and is used to ensure the migration in the opposite direction (reinsertion into the storing electrode 3).

(22) According to another particular operating mode, the application of a current I.sub.actuation between the electrodes 11 and 12 for a time t.sub.actuation is used to make the ions migrate to the electrode 11 (formation of the electrodeposit), and a voltage U.sub.actuation is applied for a time t.sub.actuation and is used to ensure the migration in the opposite direction (reinsertion into the storing electrode 3).

(23) According to another particular operating mode, the application of a voltage U.sub.actuation between the electrodes 11 and 12 for a time t.sub.actuation is used to make the ions migrate to the electrode 11 (formation of the electrodeposit), and a current I.sub.actuation is applied for a time t.sub.actuation and is used to ensure the migration in the opposite direction (reinsertion into the storing electrode 3).

(24) The various aforementioned modes allow the electrodeposit to be formed in various ways to meet constraints that may be different from one application to the next. For example, the use of a high actuation current allows the electrodeposit to be formed in a very short space of time, whereas the use of a voltage allows the thickness of the formed electrodeposit to be precisely controlled.

(25) According to another variant of the invention illustrated in FIGS. 5a and 5b, the tuneable electronic component furthermore includes an additional electrode 9, called the insertion electrode, that is saturatable with the ion in question, thereby making it possible to make use of intermediate states. Specifically, a saturatable electrode (for example of Si, Ge or Al in the case where the ion is Li.sup.+) is capable of absorbing an amount of ions until saturation, from which point ions reaching the electrode start to form a layer of the metal of the ion in question and a phase of electrodeposition commences. In this way, the response of the intermediate zone defined between the electrodes 21/22 is influenced by the various states of insertion of the layer 9, and the number of possible intermediate states of the component is increased.

(26) According to another variant of the invention illustrated in FIGS. 6a and 6b, the tuneable electronic component takes advantage of the possible variation associated with insertion/deinsertion into/from the storing electrode. This approach implies the addition of a pair of electrodes 31/32 separated by the storing electrode 3, and allowing, by virtue of this architecture, the response of the tuneable component to be modulated (the response modulated being the same as that between 21/22 or a different response). According to this variant, the contacts of the electrodes 21 and 31 are redistributed to the bottom side (in the figures) by way of vias through the substrate 7.

(27) According to another variant of the invention illustrated in FIGS. 7a and 7b, the tuneable electronic component may also have a configuration allowing a formation of the electrodeposit in a plane parallel to the substrate (in the variants of the invention described above, the electrodeposit is formed in a plane orthogonal to the substrate). The electrodes 12/3/11 are placed in planes parallel to the plane of the substrate.

(28) Advantageously it is possible to produce, according to the present invention, an assembly of tuneable electronic functions on a given substrate is illustrated in FIGS. 8a and 8b and comprising a plurality of types of tuneable blocks according to the architecture of the invention, each block being independently controllable. All the blocks may be identical, or have certain differences.

(29) On a common substrate 7, the various blocks comprise:

(30) a pair of actuating electrodes 11i/12i;

(31) a pair of measuring electrodes 21i/22i;

(32) a storing electrode 3i;

(33) an ionic conductor 4i;

(34) an internal insulator 5i;

(35) a common external insulator 6 encapsulating all of the aforementioned elements.

(36) According to the present invention, it is thus possible to vary a number of properties that are, for example: electronic (non-volatile memories NVMs, switches, RF switch), thermal (thermal switch), optical (filters, waveguides), ferro/magneto (capacitor), etc.

(37) Exemplary Process for Producing a Tuneable Component According to the Invention:

(38) Step 1:

(39) A substrate, for example made of silicon, or of glass, or of another semiconductor, is cleaned. The cleaning may comprise a heat treating step (200 C., 15 min), followed by an RCA chemical treatment (for example based on NH.sub.4OH:H.sub.2O.sub.2 and HCl:H.sub.2O.sub.2).

(40) Step 2:

(41) Two 0.25 m-thick actuating electrodes, which are for example made of Cu or Pt, are deposited and structured. A layer of Pt deposited by PVD sputtering may be structured by photolithography and etched in an aqua regia type chemical solution (mix of HCl+HNO.sub.3).

(42) Step 3:

(43) A 0.25 m-thick measuring electrode, which is for example made of Ni, Cu, Mo, W, Pt or a transparent conductive oxide of ITO composition, is deposited and structured. A layer of Pt deposited by PVD sputtering may be structured by photolithography and etched in an aqua regia type chemical solution (mix of HCl+HNO.sub.3). The layer of the first measuring electrode may be obtained simultaneously with those of the actuating electrodes if the selected material is the same.

(44) Step 4:

(45) A 1 m-thick electrode for storing ions, which is for example an LiCoO.sub.2 oxide composition (in this precise case it is a question of storing lithium ions Li.sup.+), is deposited and structured. The LiCoO.sub.2 layer may be obtained by sputtering an LiCoO.sub.2 target under Ar and may be etched in an Ar inductively coupled plasma.

(46) Step 5:

(47) A 1.5 m-thick ionic conductor, which is for example made of LiPON (Li.sup.+ ion conduction), is deposited and structured. The LiPON layer may be deposited by reactive sputtering of a Li.sub.3PO.sub.4 target under nitrogen N.sub.2, structured by photolithography and etched in an Ar inductively coupled plasma.

(48) Step 6:

(49) A 1 m-thick passivating dielectric, which is for example made of SiO.sub.2, Si.sub.3N.sub.4, Al.sub.2O.sub.3 or a polymer, is deposited and structured. For example, a layer of Si.sub.3N.sub.4 may be deposited by PECVD, structured by photolithography and etched in an Ar inductively coupled plasma.

(50) Step 7:

(51) A 0.25 m-thick second measuring electrode, which is for example made of Ni, Cu, Mo, W, Pt or a transparent conductive oxide of ITO composition, is deposited and structured. A layer of Pt deposited by physical vapour phase (PVD) sputtering may be structured by photolithography and etched in an aqua regia type chemical solution (mix of HCl+HNO.sub.3).

(52) Step 8:

(53) A 2 m-thick passivating dielectric, which is for example made of SiO.sub.2, Si.sub.3N.sub.4, Al.sub.2O.sub.3 or a polymer, is deposited and structured. For example, a layer of Si.sub.3N.sub.4 may be deposited by plasma-enhanced chemical vapour deposition (PECVD), structured by photolithography and etched in an Ar inductively coupled plasma.

(54) The advantages of the present invention are outlined in Table 2 below and their benefit is especially seen:

(55) in terms of geometry, which is: volumic (thin layer), continuous and able to ensure a contact over a large area and/or height;

(56) in terms of modulation ratio, which is: high insofar as the two extreme states are associated with two intrinsically different materials (the ionic conductor and the electrodeposit);

(57) in terms of intermediate states: possible states corresponding to a certain thickness of the formed electrodeposition layer, said thickness theoretically being controllable on the nanoscale;

(58) in terms of response time, which is: shorter than in the case of an electrochemical actuation by insertion, because the diffusion occurs only within a single electrode contrary to systems comprising two electrodes.

(59) TABLE-US-00002 TABLE 2 Comparison of the performance of tuneable components (prior art vs. invention) with respect to the actuating mode implemented. Electrochemical Electrochemical actuation by actuation by insertion filament formation Invention Geometry 2D/3D (+) 1D () 2D/3D (+) Modulation Average () High (+) High (+) ratio Intermediate Yes (+) No () Yes (+) states Response >100 s () <1 s (+) 1-100 s time Actuation low (1-2 V) (+) low (1-2 V) (+) low (1-2 V) (+) voltage Energy low (0.1-1 J) (+) low (0.1-1 J) (+) low (0.1-1 J) (+) consumption

(60) By virtue of the present invention, it is thus possible to design tuneable electronic components that may especially be resistive, or capacitive or inductive.

(61) They may also be electrical microswitches (switches), radiofrequency electrical microswitches (RF switches), thermal valves or microswitches, non-volatile memory, non-volatile multiple valued logic memories (multiple valued logic memories).