SWITCHES BASED ON PHASE CHANGE MATERIAL

Description

Domaine technique

[0001] This description relates generally to electronic devices. This description relates more particularly to switches based on a phase-change material, capable of alternating between a crystalline, electrically conductive phase and an amorphous, electrically insulating phase. Technique antérieure

[0002] Various applications benefit from switches, or interrupters, based on a phase-change material to allow or prevent the flow of an electric current in a circuit. Such switches can be implemented in particular in radiofrequency communication applications, for example to switch an antenna between transmission and reception modes, activate a filter corresponding to a frequency band, etc.

[0003] Existing phase change material switches, however, suffer from various drawbacks. An example of prior art is found in document US2010012916. The document discloses a phase change material switch. Summary of the invention

[0004] There is a need to improve existing phase change material based switches.

[0005] For this, one embodiment provides a switch comprising: first, second and third electrodes; a region of phase change material connecting the first, second and third electrodes; and first, second and third heating elements connected between a first face of the region of phase change material and the first, second and third electrodes, respectively, the second and third heating elements being adapted to modify the state of the phase change material in first and second zones within said region.

[0006] According to one embodiment, the first heating element is intended to modify the state of the phase change material in a third zone, different from the first and second zones, within the phase change material region.

[0007] According to one embodiment, the switch further comprises a fourth electrode and a fourth heating element connected between the first face of the phase change material region and the fourth electrode, the fourth heating element being intended to modify the state of the phase change material in a fourth zone, different from the first and second zones, within said region.

[0008] According to one embodiment, the first, second and third electrodes are respectively connected to first, second and third conductive regions each corresponding to a conduction electrode of a MOS transistor formed in a substrate.

[0009] According to one embodiment, the first, second and third electrodes are respectively connected to first, second and third control circuits each comprising a node for applying a control potential.

[0010] According to one embodiment, the first and second zones interpenetrate.

[0011] According to one embodiment, the first and second zones are separate.

[0012] According to one embodiment, the first and second electrodes are intended to be connected to a radiofrequency communication circuit and the third electrode is intended to be brought to a reference potential.

[0013] According to one embodiment, the switch further comprises at least one third additional heating element connected between the first face of the phase change material region and the third electrode, each third additional heating element being intended to modify the state of the phase change material in a second additional zone within said region.

[0014] According to one embodiment, the switch further comprises at least one second additional heating element connected between the first face of the phase change material region and the second electrode, each second additional heating element being intended to modify the state of the phase change material in a first additional zone within said region.

[0015] According to one embodiment, a second face of the phase change material region, opposite the first face, is coated with a conductive layer.

[0016] According to one embodiment, the phase change material region is made of a chalcogenide material. Brève description des dessins

[0017] These and other features and advantages will be set forth in detail in the following description of particular embodiments given without limitation in relation to the attached figures, among which: there figure 1A , there figure 1B and the figure 1C are schematic and partial views, respectively from above and in section according to planes BB and CC of the figure 1A , of an example of a switch based on a phase change material according to one embodiment; figure 2A , there figure 2B and the figure 2C are top views, schematic and partial, illustrating different states of the switch of the figures 1A à 1C ; there figure 3A , there figure 3B and the figure 3C illustrate, schematically and partially, differences in operation between an example of phase change memory and the switch of figures 1A à 1C ; there figure 4A and the figure 4C are schematic and partial views, respectively from above and in section according to the plane CC of the figure 4A , of an example of a switch based on a phase change material according to one embodiment; figure 5A and the figure 5B are schematic and partial views, respectively from above and in section along plane BB of the figure 5A , of an example of a switch based on a phase change material according to one embodiment; figure 6 is a top view, schematic and partial, of an example of a switch based on a phase change material according to an embodiment; figure 7 is a top view, schematic and partial, of an example of a switch based on a phase change material according to an embodiment; and the figure 8 is a top view, schematic and partial, of an example of a switch based on a phase change material according to one embodiment. Description des modes de réalisation

[0018] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0019] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the control circuits for switches based on a phase-change material and the applications in which such switches may be provided have not been detailed, the described embodiments and variants being compatible with the control circuits for switches based on a conventional phase-change material and with the usual applications implementing switches based on a phase-change material.

[0020] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0021] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0022] Unless otherwise specified, the expressions “about”, “approximately”, “substantially”, and “in the order of” mean to within 10%, preferably to within 5%.

[0023] There figure 1A is a top view, schematic and partial, of an example of a switch 100 based on a phase change material according to one embodiment. figure 1B and the figure 1C are sectional views of the switch 100 along planes BB and CC, respectively, of the figure 1A .

[0024] In the example shown, the switch 100 comprises a substrate 101. The substrate 101 is for example a wafer or a piece of wafer made of a semiconductor material, for example silicon. By way of example, the substrate 101 is of the CMOS (Complementary Metal-Oxide-Semiconductor) type and comprises a plurality of MOS (Metal-Oxide-Semiconductor) transistors not detailed in figures 1A à 1C so as not to overload the drawing.

[0025] In the illustrated example, a region 103 of a phase change material extends laterally over and in contact with a face of the substrate 101 (the upper face of the substrate 101, in the orientation of the figures 1B et 1C ). The region 103 has, for example, in top view, a rectangular or, as in the example shown, substantially square shape. This example is however not limiting, the region 103 being able, as a variant, to have any shape.

[0026] For example, the region 103 of the switch 100 is made of a so-called "chalcogenide" material, i.e. a material or alloy comprising at least one chalcogen element, for example a material from the family of germanium telluride (GeTe), antimony telluride (SbTe), germanium-antimony-tellurium (GeSbTe), more commonly referred to by the acronym "GST", or nitrogen-doped germanium telluride (GeTeN). The region 103 is for example made of GeTe, SbTe, GeSbTe or GeTeN. The region 103 is for example made of a continuous layer of phase change material.

[0027] In the example shown, the face of the region 103 made of phase change material opposite the substrate 101 (the upper face of the region 103, in the orientation of the figures 1B et 1C ) is coated with an electrically conductive layer 105. The conductive layer 105 is for example deposited on the upper face of the region 103 made of phase change material. In the example shown, the conductive layer 105 is continuous and completely covers the face of the region 103 opposite the substrate 101. The conductive layer 105 constitutes for example an upper electrode of the switch 100 and is for example intended to be brought to a reference potential, for example ground. The layer 105 is for example based on a metal or a metal alloy. For example, the layer 105 is made of titanium nitride (TiN). The layer 105 has for example a thickness of between 25 and 100 nm, for example of the order of 50 nm. The layer 105 has not been shown in figure 1A so as not to overload the drawing. Alternatively, layer 105 may be omitted.

[0028] In the illustrated example, the switch 100 further comprises electrodes 107, more precisely four electrodes 107a, 107b, 107c and 107d, in this example. The electrodes 107 of the switch 100 are insulated from each other. In the example shown, each electrode 107 has, in side view, an L-shape, a horizontal part of which extends laterally in the substrate 101 directly above the layer 103, the horizontal part of each electrode 107 being separated from the layer 103 by a non-zero distance, and a vertical part of which extends vertically in the thickness of the substrate 101 from a zone of the upper face of the substrate 101 not coated with the region 103. The vertical part of each electrode 107 may, as in the example shown, protrude from the upper face of the substrate 101. This example is however not limiting, the electrodes 107 being able, as a variant, to be flush with the upper face of the substrate 101.

[0029] The electrodes 107 of the switch 100 are for example made of a conductive material, for example a metal or a metal alloy. For example, the electrodes 107 are made of copper. In order to simplify the production of the switch 100, the electrodes 107 have for example substantially identical structures and compositions, apart from manufacturing variations.

[0030] The electrodes 107a and 107b are for example intended to be connected to a radiofrequency communication circuit and the electrodes 107c and 107d are for example intended to be brought to a reference potential, for example ground. For example, the electrodes 107c and 107d may be interconnected. In the example shown, the electrode 107a is an input electrode of the switch 100 to which a radiofrequency signal RF_IN is applied, the electrode 107b is an output electrode of the switch 100 transmitting a radiofrequency signal RF_OUT, and the electrodes 107c and 107d are connected to ground.

[0031] In the example shown, the switch 100 further comprises heating elements 109 (“heater”, in English), more precisely four heating elements 109a, 109b, 109c and 109d, in this example. The heating elements 109 of the switch 100 are insulated from each other. The heating elements 109a, 109b, 109c and 109d are connected between the face of the region 103 coating the substrate 101 (the lower face of the region 103, in the orientation of the figures 1B et 1C ) and the electrodes 107a, 107b, 107c and 107d, respectively. In the illustrated example, each heating element 109a, 109b, 109c, 109d has an L shape, a horizontal part of which extends laterally over and in contact with the horizontal part of the L formed by the corresponding electrode 107a, 107b, 107c, 107d, and a vertical part of which, located directly above the region 103 made of phase-change material, extends vertically in the thickness of the substrate 101 from the upper face of the substrate 101 to the corresponding electrode 107a, 107b, 107c, 107d. In the orientation of the figures 1B et 1C , the upper end of the vertical part of each heating element 109 is flush with an area of ​​the upper face of the substrate 101 coated with the region 103 and is in mechanical contact with the lower face of the region 103. The heating elements 109 contact the region 103 in different locations, for example spaced from each other by a few tens of nanometers. figures 1A à 1C illustrate an example in which the switch 100 comprises a single continuous conductive layer 105. However, this example is not limiting and the switch 100 may, as a variant, comprise several disjoint conductive layers, for example four disjoint conductive layers located respectively in line with contact zones of the heating elements 109 with the lower face of the region 103.

[0032] In the illustrated example, the switch 100 further comprises conductive regions 111, more precisely four regions 111a, 111b, 111c and 111d, in the example shown. The conductive regions 111 of the switch 100 are for example insulated from each other, and correspond for example to conduction electrodes (source or drain) of MOS transistors formed in the substrate 101. In the orientation of the figures 1B et 1C , each conductive region 111a, 111b, 111c, 111d is in mechanical contact, by its upper face, with the lower face of the horizontal part of the L formed by the electrode 107a, 107b, 107c, 107d, respectively.

[0033] There figure 2A , there figure 2B and the figure 2C are top views, schematic and partial, illustrating different states of the switch of the figures 1A à 1C .

[0034] Phase change materials are, generally speaking, materials capable of alternating, under the effect of a variation in temperature, between a crystalline phase and an amorphous phase, the amorphous phase having a higher electrical resistance than that of the crystalline phase. In the case of the switch 100, this phenomenon is taken advantage of to obtain: a first state ( figure 2A ), called the “on state”, allowing the transmission of a radiofrequency signal between the electrodes 107a and 107b, when the material of two zones 113a and 113b of the region 103, located respectively in line with the vertical parts of the heating elements 109a and 109b, is in the crystalline phase and when at least part of the material of two other zones 113c and 113d of the region 103, located respectively in line with the vertical parts of the heating elements 109c and 109d, is in the amorphous phase; a second state ( figure 2B ), called a "reflective off-state", preventing the transmission of a radiofrequency signal between the electrodes 107a and 107b, when at least part of the material of the areas 113a and 113b of the region 103 is in the amorphous phase and when the material of the areas 113c and 113d of the region 103 is in the crystalline phase; and a third state ( figure 2C ), called the “absorbing blocked state”, allowing partial transmission of a radiofrequency signal between the electrodes 107a and 107b, and possibly between the electrode 107a and the electrodes 107c and 107d, when the material of the zones 113a, 113b, 113c and 113d of the region 103 is in the crystalline phase.

[0035] In the example shown, each zone 113a, 113b, 113c, 113d of the region 103 has the shape of a spherical cap substantially centered, in top view, relative to the place where the vertical part of the heating element 109a, 109b, 109c, 109d, intended to modify the state of the phase change material in the corresponding zone, is in mechanical contact with the lower face of the region 103. In the example illustrated, the zones 113a, 113b, 113c and 113d interpenetrate, each zone 113a, 113b, 113c, 113d being in contact with all the other zones. For example, each zone 113a, 113b, 113c, 113d has, in top view, a maximum lateral dimension (corresponding, in this example, to the diameter of the base circle of the spherical cap formed by the zone 113a, 113b, 113c, 113d considered) of the order of a few tens of nanometers, for example equal to approximately 40 nm.

[0036] When switching the switch 100 between the on and off reflective states, control voltages are for example applied simultaneously between the regions 111a, 111b, 111c and 111d, on the one hand, and the layer 105, on the other hand, in order to cause a flow of current through the heating elements 109a, 109b, 109c and 109d, respectively. This current causes, by Joule effect then by radiation and / or conduction inside the structure of the switch 100, in particular through the layer 103, a rise in temperature inside the zones 113a, 113b, 113c and 113d from the lower face of the region 103.

[0037] More specifically, to switch the switch 100 from the reflective off state to the on state, the zones 113a and 113b of the region 103 made of phase change material are heated, by means of the heating elements 109a and 109b, for example to a temperature T1 and for a duration d1. The temperature T1 and the duration d1 are chosen so as to cause a phase change of the material of the zones 113a and 113b from the amorphous phase to the crystalline phase. The temperature T1 is for example higher than a crystallization temperature and lower than a melting temperature of the material of the region 103. For example, the temperature T1 is between 150 and 350°C and the duration d1 is less than 1 µs. In the case where region 103 is made of germanium telluride, the temperature T1 is for example equal to approximately 300°C and the duration d1 is for example between 100 ns and 1 µs.

[0038] Furthermore, the zones 113c and 113d of the region 103 made of phase change material are heated, by means of the heating elements 109c and 109d, for example to a temperature T2 higher than the temperature T1, and for a duration d2 lower than the duration d1. The temperature T2 and the duration d2 are chosen so as to cause a phase change of the material of the zones 113c and 113d from the crystalline phase to the amorphous phase. The temperature T2 is for example higher than the melting temperature of the phase change material. For example, the temperature T2 is between 600 and 1000°C and the duration d2 is less than 500 ns. In the case where the region 103 is made of germanium telluride, the temperature T2 is for example equal to approximately 700°C and the duration d2 is for example equal to approximately 100 ns.

[0039] When switching the switch 100 between the reflective off state and the on state, the heating elements 109a, 109b, 109c and 109d are, for example, controlled simultaneously. This advantageously reduces the switching time.

[0040] Conversely, to switch the switch 100 from the on state to the reflective off state, the areas 113a and 113b are heated, by means of the heating elements 109a and 109b, for example to the temperature T2 and for the duration d2. Furthermore, the areas 113c and 113d are heated, by means of the heating elements 109c and 109d, for example to the temperature T1 and for the duration d1.

[0041] Thus, during switching between the on state and the reflective off state, the heating elements 109a and 109b, on the one hand, and the heating elements 109c and 109d, on the other hand, are for example controlled simultaneously and in opposition. For example, the heating elements 109c and 109d are intended to be controlled so as to change the zones 113c and 113d of phase change material from a first state to a second state (for example from the crystalline state to the amorphous state) when the heating elements 109a and 109b are controlled so as to change the zones 113a and 113b of phase change material from the second to the first state (from the amorphous state to the crystalline state, in this example).

[0042] The switching between the reflective off state and the absorbing off state is for example analogous to the switching between the conducting and reflective off state described above, with the difference that only the heating elements 109a and 109b are implemented for the switching between the reflective off state and the absorbing off state, the material of the regions 113c and 113d remaining in the crystalline phase during this switching. For example, to switch the switch 100 from the reflective off state to the absorbing off state, the regions 113a and 113b of the region 103 are heated to the temperature T1 and for the duration d1. Conversely, to switch the switch 100 from the absorbing off state to the reflective off state, the regions 113a and 113b are for example heated to the temperature T2 and for the duration d2.

[0043] Furthermore, the switching between the on and off absorbing states is for example analogous to the switching between the on and off reflecting states described above, with the difference that only the heating elements 109c and 109d are implemented for the switching between the on state and the off absorbing state, the material of the areas 113a and 113b remaining in the crystalline phase during this switching. For example, to switch the switch 100 from the on state to the off absorbing state, the areas 113c and 113d of the region 103 are heated to the temperature T1 and for the duration d1. Conversely, to switch the switch 100 from the off absorbing state to the on state, the areas 113c and 113d are for example heated to the temperature T2 and for the duration d2.

[0044] The values ​​of the temperatures T1 and T2 and of the heating durations d1 and d2 may be substantially identical for each of the zones 113a, 113b, 113c, 113d.

[0045] Alternatively or additionally, the heating elements 109a, 109b, 109c and 109d of the switch 100 may be controlled by control circuits 115, more precisely by four control circuits 115a, 115b, 115c and 115d, respectively, in this example. Each circuit 115a, 115b, 115c, 115d comprises: a node 117 intended to be connected to the corresponding electrode 107a, 107b, 107c, 107d; an inductive element 119 connected between the node 117 and another node 121 for applying a control potential, for example a direct current (DC) potential; a capacitive element 123 connected between the node 121 and another node for applying a reference potential, for example ground; and another capacitive element 125 connected between the node 117 and, in the case of the circuits 115a and 115b, another node 127 for applying a radiofrequency signal corresponding for example to the signal RF_IN for the circuit 115a and to the signal RF_OUT for the circuit 115b or, in the case of the circuits 115c and 115d, another node for applying a reference potential, for example ground.

[0046] For example, circuits 115a, 115b, 115c, and 115d may be formed in substrate 101 or another substrate superimposed on substrate 101, in the orientation of the figures 1B et 1C .

[0047] When switching the switch 100 between the on, off reflective and off absorbing states, the control circuits 115a, 115b, 115c and 115d may, in conjunction with the regions 111 or in place of the regions 111, be implemented to apply to the heating elements 109a, 109b, 109c and 109d the appropriate voltage allowing the corresponding regions 113a, 113b, 113c and 113d to alternate between the amorphous and crystalline phases as previously explained. In other words, the bias voltage of each heating element 109 of the switch 100 may be applied either by means of the regions 111 alone, or by means of the circuits 115 alone, or jointly by means of the regions 111 and the circuits 115.

[0048] The switch 100 advantageously uses the operating principle of a PCRAM (Phase-Change Random Access Memory) type memory but with four memory areas, in the example shown, unlike a cell of a PCRAM memory which only uses one. The switch 100 is further distinguished from existing phase-change material-based radiofrequency switches in that it does not require switching the entire volume of phase-change material in the region 103. In the switch 100, the four memory areas are obtained thanks to the presence of five terminals, in this case the heating elements 109 and the conductive region 105, arranged so as to modify the phase of the material in the areas 113.The presence of these four memory areas allows the structure to meet the requirements of a radio frequency switch, particularly in terms of R off / R on ratio, unlike existing PCRAM memory cells which have lower R off / R on ratios. For example, the R off / R on ratio of switch 100 is greater than one thousand, or even greater than ten thousand, while a PCRAM memory cell has an R off / R on ratio of the order of one hundred.

[0049] An advantage of the switch 100 is that the reflective off-state provides better isolation, for example improved by about -20 dB, between the electrodes 107a and 107b compared to the case of a similar switch but lacking for example the electrodes 107c and 107d, the heating elements 109c and 109d, and the regions 111c and 111d. Another advantage of the switch 100 is that it is possible to take advantage of the absorbing off-state to attenuate the signal transmitted between the conduction electrodes 107a and 107b.

[0050] There figure 3A , there figure 3B and the figure 3C illustrate, schematically and partially, differences in operation between an example of phase change memory and the switch of figures 1A à 1C .

[0051] There figure 3A schematically represents a zone 350 in phase change material decomposed into columns each comprising one hundred elementary square meshes 351. In the left part of the figure 3A , the material of the elementary meshes 351 of each column is in the crystalline state. For example, each elementary mesh 351 has an elementary resistance substantially equal to 1 Ω, in the crystalline state, and substantially equal to 1 kΩ, in the amorphous state. On the left, in the example illustrated, the zone 350 has a resistance in the on state R on substantially equal to 100 Ω (one hundred elementary meshes of 1 Ω in series). The resistance R on corresponds for example to a resistance in the on state between a lower input finger 353 and an upper electrode 355. In the right part of the figure 3A , the elementary mesh 351 in contact with the finger 353 switches from the crystalline state to the amorphous state. The zone 350 then has a resistance in the blocked state R off substantially equal to 10,099 Ω (99 elementary meshes of 1 Ω and one elementary mesh of 10 kΩ in series). The resistance R off corresponds to a resistance in the blocked state between the finger 353 and the electrode 355. In the configuration illustrated in figure 3A , the R off / R on ratio is substantially equal to one hundred (10,099 / 100). This configuration typically corresponds to a PCRAM memory comprising a lower electrode (lower finger 353) and an upper electrode 355. Such an R off / R on ratio is not compatible with a radio frequency switch application.

[0052] There figure 3B schematically represents a zone 360 ​​in phase change material decomposed into columns each comprising one hundred elementary square meshes 361. In the left part of the figure 3B , the material of the elementary meshes 361 of each column is in the crystalline state. For example, each elementary mesh 361 has an elementary resistance substantially equal to 1 Ω, in the crystalline state, and substantially equal to 1 kΩ, in the amorphous state. On the left, in the illustrated example, the zone 360 ​​has, between a lower input finger 353i and a lower output finger 353o, a resistance in the on state R on substantially equal to 7 Ω (two half-squares of 0.5 Ω and six full squares of 1 Ω in series between the fingers 353i and 353o). In the right part of the figure 3B , the elementary meshes 361 in contact respectively with the fingers 363i and 363o switch from the crystalline state to the amorphous state. The zone 360 ​​then has, between the fingers 363i and 363o, a resistance in the blocked state R off substantially equal to 10,006 Ω (two half-squares of 5 kΩ and six full squares of 1 Ω in series between the fingers 353i and 353o). In the configuration illustrated in figure 3B , the R off / R on ratio is approximately equal to 1,429 (10,006 / 7). Compared to the configuration of the figure 3A , the configuration of the figure 3B advantageously allows the R off / R on ratio to be increased by a factor greater than 10. The switching of the elementary zones 361 in contact with the fingers 363i and 363o is carried out for example by respectively applying a first control signal between the input finger 363i and an upper electrode 365, and a second control signal, different from the first control signal, between the output finger 363o and the electrode 365. The input fingers 363i and output fingers 363o are for example analogous or identical to two of the heating elements 109 of the switch 100, for example the heating elements 109b and 109d, and the upper electrode 365 is for example analogous or identical to the conductive layer 105 of the switch 100.

[0053] The R off / R on ratio can be further increased by bringing the input 363i and output 363o fingers closer together as shown in figure 3C . In this case, the resistance R on is equal to about 1 Ω (two half-squares of 1 Ω in series between fingers 353i and 353o) and the resistance R off is equal to about 10 kΩ (two half-squares of 5 kΩ in series). In this case, the ratio R off / R on is equal to about 10,000. Compared to the configuration of the figure 3A , the configuration of the figure 3C allows the R off / R on ratio to be increased by a factor of around one hundred.

[0054] The switch 100 takes advantage of a PCRAM-type structure comprising at least two lower electrodes making it possible to create two memory areas using a third upper electrode, this configuration making it possible to retain the advantages of a PCRAM memory in terms of switching time while gaining a factor of ten, one hundred, or more on the R off / R on ratio.

[0055] There figure 4A is a top view, schematic and partial, of an example of a switch 200 based on a phase change material according to an embodiment. figure 4C is a sectional view, according to plane CC of the figure 4A , of the switch 200. The switch 200 presents, in sectional view along the plane BB of the figure 4A , a structure similar or identical to that of the switch 100 illustrated in figure 1B .

[0056] The 200 switch of the figures 4A et 4C includes common elements with the 100 switch of the figures 1A à 1C . These common elements will not be detailed again below. The switch 200 of the figures 4A et 4C differs from the 100 switch of the figures 1A à 1C in that the switch 200 is devoid of the electrode 107c, the heating element 109c and the conductive region 111c. The operation of the switch 200 is for example analogous to that of the switch 100 previously explained in relation to the figures 1A à 1C The operation of switch 200 differs from that of switch 100 in that, in switch 200, only heating elements 109a, 109b and 109d are controlled to achieve the on, reflective off and absorbent off states.

[0057] Although this has not been illustrated in figure 4C , the electrode 107d of the switch 200 can be connected to the control circuit 115d previously described in relation to the figure 1C .

[0058] An advantage of the switch 200 is that it has a structure comprising fewer elements than the switch 100. This makes it possible to simplify the production and control of the switch 200 compared to the switch 100.

[0059] There figure 5A is a top view, schematic and partial, of an example of a switch 300 based on a phase change material according to one embodiment. figure 5B is a sectional view, according to plane BB of the figure 5A , of the switch 300. The switch 300 presents, in sectional view along the plane CC of the figure 5A , a structure similar or identical to that of the switch 200 illustrated in figure 4C .

[0060] The 300 switch of the figures 5A And 5B includes common elements with the 200 switch of the figures 4A et 4C . These common elements will not be detailed again below. The switch 300 of the figures 5A And 5B differs from the 200 switch of the figures 4A et 4C in that the heating element 109a of the switch 300 is not intended to modify the state of the phase change material in the area 113a of the region 103, the material remaining for example in the crystalline phase within this area regardless of the state of the switch 300. For example, the control circuit 115a and / or the conductive region 111a may be omitted.

[0061] The operation of the switch 300 is for example analogous to that of the switch 100 described previously in relation to the figures 1A à 1C . The operation of switch 300 differs from that of switch 100 in that, in switch 300, heating element 109a is not subject to any control potential intended to change the phase of zone 113a. Although this has not been illustrated in figure 5B , the electrode 107b of the switch 300 can be connected to the control circuit 115b previously described in relation to the figure 1B .

[0062] An advantage of the switch 300 is that it has a structure comprising fewer elements than the switch 100. This makes it possible to simplify the production and control of the switch 300 compared to the switch 100.

[0063] There figure 6 is a schematic and partial top view of an example of a switch 400 based on a phase change material according to one embodiment. The switch 400 presents, in sectional view along planes BB and CC of the figure 6 , a structure analogous to that of the switch 100 illustrated in Figures 1B and 1C , respectively.

[0064] The 400 switch of the Figure 6 includes common elements with the 100 switch of the Figures 1A to 1C . These common elements will not be detailed again below. The switch 400 of the Figure 6 differs from the 100 switch of the Figures 1A to 1Cin that the areas 113a, 113b, 113c and 113d of the switch 400 are disjoint. In the example shown, each area 113a, 113b, 113c, 113d is separated from the other areas by parts of the region 103 which remain in the crystalline phase regardless of the state of the switch 400, the region 103 being for example in the crystalline phase at the end of the manufacture of the switch 400. The switch 400 corresponds for example to a case in which the heating elements 109 are further apart from each other than in the case of the switch 100, for example due to manufacturing dispersions.

[0065] Although the Figure 6 illustrates an example in which all of the zones 113a, 113b, 113c and 113d are disjoint, the switch 400 could, alternatively, comprise at least two contiguous, or interpenetrating, zones among the zones 113a, 113b, 113c and 113d.

[0066] The operation of the switch 400 is for example identical to that of the switch 100 explained previously in relation to the Figures 1A to 1C .

[0067] There Figure 7 is a top view, schematic and partial, of an example of a switch 500 based on a phase change material according to one embodiment.

[0068] The 500 switch of the Figure 7 includes common elements with the 100 switch of the Figures 1A to 1C . These common elements will not be detailed again below. The 500 switch of the Figure 7 differs from the 100 switch of the Figures 1A to 1C in that the switch 500 includes a plurality of heating elements 109c connected to the electrode 107c, and a plurality of heating elements 109d connected to the electrode 107d. The heating elements 109c and 109d have not been shown in Figure 7in order not to overload the drawing. The heating elements 109c and 109d of the switch 500 are capable of forming, in the region 103 of phase change material, several contiguous zones 113c and several contiguous zones 113d, each zone 113c, 113d being substantially centered on the place where the heating element 109c, 109d is in mechanical contact with the region 103. The heating elements 109c and 109d are for example connected to the region 103, on the one hand, and to the electrode 107c or 107d, on the other hand. The operation of the switch 500 is for example identical to that of the switch 100 previously explained in relation to the Figures 1A to 1C . The switching of zones 113c and 113d of the switch 500 between the crystalline and amorphous phases is for example controlled simultaneously.

[0069] There Figure 7illustrates an example in which the switch 500 comprises two rows of zones 113c and two rows of zones 113d, for example each associated with a row of heating elements 109c or 109d. This example is however not limiting, the switch 500 being able to comprise any number, greater than or equal to one, for example between one and five, of rows of zones 113c and rows of zones 113d. The zones 113c and 113d can, as a variant, be organized in a manner other than in the form of rows. Furthermore, although the Figure 7illustrates an example in which the rows comprise identical numbers of zones 113c or 113d, this example is not limiting, the switch 500 being able, as a variant, to have any number, greater than or equal to one, of zones 113c or 113d per row. In other words, the switch 500 can comprise any number, greater than or equal to one, of heating elements 109c and any number, greater than or equal to one, of heating elements 109d, these heating elements being able to be organized in the form of any number of rows each comprising any number, greater than or equal to one, of heating elements.

[0070] An advantage of the 500 switch is that paralleling areas 113c and 113d allows for a reduced series resistance of the ground connections and increased isolation when the switch is in the reflective off state.

[0071] There figure 8is a top view, schematic and partial, of an example of a switch 600 based on a phase change material according to one embodiment.

[0072] The 600 switch of the figure 8 includes common elements with the 500 switch of the Figure 7 . These common elements will not be detailed again below. The 600 switch of the figure 8 differs from the 500 switch of the Figure 7 in that the switch 600 comprises a plurality of heating elements 109a and a plurality of heating elements 109b. The heating elements 109a and 109b have not been shown in figure 8 so as not to overload the drawing. The heating elements 109a and 109b of the switch 600 are capable of forming, in the region 103 of phase change material, several pairs of contiguous zones 113a 113b, each zone 113a, 113b being substantially centered on the location where the heating element 109a, 109b is in mechanical contact with the region 103.

[0073] In the example shown, the heating elements 109a, 109b, 109c and 109d of the switch 600 are capable of forming several assemblies 601 each comprising zones 113a and 113b interposed laterally between a row of zones 113c and a row of zones 113d. More precisely, in the example shown, the switch 600 comprises three assemblies 601-1, 601-2 and 601-3 interposed laterally between the electrodes 107c and 107d. In the example shown, areas 113c of set 601-1 and adjacent areas 113d of set 601-2 interpenetrate, and areas 113c of set 601-2 and adjacent areas 113d of set 601-3 interpenetrate.

[0074] In the example illustrated in figure 8, the electrodes 107a of the assemblies 601-1, 601-2 and 601-3 are connected to the same electrode 607a, and the electrodes 107b of the assemblies 601-1, 601-2 and 601-3 are connected to the same electrode 607b. Furthermore, although this has not been detailed in figure 8 , the zones 113c of the assemblies 601-1, 601-2 and 601-3 are for example connected to the electrode 107c, and the zones 113d of the assemblies 601-1, 601-2 and 601-3 are for example connected to the electrode 107d.

[0075] Although the figure 8illustrates an example in which the switch 600 comprises three sets 601 each comprising a row of zones 113c and a row of zones 113d, the switch 600 may alternatively comprise any number, greater than or equal to one, of sets 601, each set 601 may further comprise any number, greater than or equal to zero, of rows of zones 113c and rows of zones 113d. Each row of zones 113c and each row of zones 113d may further comprise any number, greater than or equal to zero, of zones 113c and 113d, respectively. In other words, the switch 600 may comprise any number, greater than or equal to one, of heating elements 109a and any number, greater than or equal to one, of heating elements 109b, the switch 600 may further comprise any number of heating elements 109c and / or 109d.

[0076] The switch 600 has operation and advantages similar or identical to those of the switch 500. The switch 600 further has the advantage, due to the paralleling of several zones 113a and 113b, of reducing the resistance between the electrodes 607a and 607b. This reduces insertion losses when the switch is in the on state, i.e., transmission in the on state is improved.

[0077] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art. In particular, those skilled in the art are able to combine: the embodiment of the switch 300 with that of the switch 100, for example so as to obtain a structure similar to that of the switch 100 but in which the heating element 109a is not controlled so as to modify the phase of the zone 113a; the embodiment of the switch 400 with that of the switch 200 or 300, for example so as to obtain a structure similar to that of the switch 200 or 300 but in which at least one of the zones 113a, 113b, 113c and 113d is disjointed from at least one of the other zones adjacent to the zone considered; the embodiment of the switch 200 with that of the switch 500 or 600, for example so as to obtain a structure similar to that of the switch 500 or 600 but devoid of the electrode 107c and the zones 113c;and the embodiment of the switch 300 with that of the switch 500 or 600, for example so as to obtain a structure similar to that of the switch 500 or 600 but in which the heating element 109a is not controlled so as to modify the phase of the zone(s) 113a.;

[0078] Finally, the practical implementation of the described embodiments and variants is within the reach of the person skilled in the art from the functional indications given above. In particular, the person skilled in the art is able to integrate the switches 100, 200, 300, 400, 500 and 600 previously described in various radio frequency devices such as a microstrip line, a coplanar waveguide (CPW), etc.

[0079] Furthermore, the described embodiments are not limited to the particular examples of materials and dimensions mentioned in this description.

Claims

1. Switch (100; 200; 300; 400; 500; 600) comprising: - first, second and third electrodes (107a, 107b, 107d; 607a, 607b, 107d); - a region (103) made of a phase-change material coupling the first, second, and third electrodes; and - first, second, and third heater elements (109a, 109b, 109d) connected between a first surface of the region of phase-change material and the first, second, and third electrodes, respectively; and - a continuous conductive layer (105) integrally coating a second surface of the region of phase-change material opposite to the first surface, the second and third heater elements (109b, 109d) being intended to modify the state of the phase-change material in first and second areas (113b, 113d) within said region by application respectively of a first control signal between the conductive layer and the second heater element, and of a second control signal between the conductive layer and the third heater element, wherein the first and second electrodes (107a, 107b; 607a, 607b) are intended to be connected to a radio frequency communication circuit and the third electrode (107d) is intended to be taken to a reference potential.

2. Switch (100; 200; 400; 500; 600) according to claim 1, wherein the first heater element (109a) is intended to modify the state of the phase-change material in a third area (113a), different from the first and second areas (113b, 113d), within the region (103) of phase-change material.

3. Switch (100; 400; 500; 600) according to claim 1 or 2, further comprising a fourth electrode (107c) and a fourth heater element (109c) connected between the first surface of the region (103) of phase-change material and the fourth electrode, the fourth heater element being intended to modify the state of the phase-change material in a fourth area (113c), different from the first and second areas (113b, 113d), within said region.

4. Switch according to claim 3, wherein the third and fourth heater elements (109d, 109c) are intended to be controlled so as to have the third and fourth zones (113a, 113c) of phase-change material change from a first state to a second state when the first and second heater elements (109a, 109b) are controlled so as to have the first and second areas (113b, 113d) of phase-change material change from the second to the first state.

5. Switch (100; 200; 300; 400; 500; 600) according to any of claims 1 to 4, wherein the first, second, and third electrodes (107a, 107b, 107d; 607a, 607b, 107d) are respectively connected to first, second, and third conductive regions (111a, 111b, 111d), each corresponding to a conduction electrode of a MOS transistor formed in a substrate (101).

6. Switch (100; 200; 300; 400; 500; 600) according to any of claims 1 to 5, wherein the first, second, and third electrodes (107a, 107b, 107d; 607a, 607b, 107d) are respectively connected to first, second, and third control circuits (115a, 115b, 115d), each comprising a node (121) of application of a control potential.

7. Switch (100; 200; 300; 500; 600) according to any of claims 1 to 6, wherein the first and second areas (113b, 113d) interpenetrate.

8. Switch (400) according to any of claims 1 to 6, wherein the first and second areas (113b, 113d) are separate.

9. Switch (500; 600) according to any of claims 1 to 8, further comprising at least one additional third heater element (109d) connected between the first surface of the region (103) of phase-change material and the third electrode (107d), each additional third heater element being intended to modify the state of the phase-change material in an additional second area (113d) within said region.

10. Switch (600) according to any of claims 1 to 9, further comprising at least one additional second heater element (109b) connected between the first surface of the region (103) of phase-change material and the second electrode (607b), each additional second heater element being intended to modify the state of the phase-change material in an additional first area (113b) within said region.

11. Switch according to any of claims 1 to 10, wherein the region of phase-change material (103) is made of at least one chalcogenide material, preferably selected from among GeTe, GeSbTe, SbTe, and GeTeN.