Spin qubit electronic device

Abstract

Spin Qubit Electronic Device This description relates to an electronic device (100) comprising: - a support (102); - a semiconductor fin (104) disposed on the support (102), in which quantum dots are intended to be formed; - several disjoint first control grids (106), arranged on the side of a first lateral face of the fin, one above the other and defining different grid levels, each configured to control the electrostatic potential of one of the quantum dots; - at least one second control grid (114) disposed on the side of a second lateral face of the fin, and configured to control the electrostatic potential of a coupling region between the quantum dots; wherein the second control grid is offset, in a direction perpendicular to the upper face of the support, relative to the first control grids. Figure for the abstract: Fig. 1

Description

Title of the invention: Electronic device with spin qubits Technical field

[0001] The present description relates generally to the field of spintronics, quantum devices and quantum computing. Prior art

[0002] There are quantum devices comprising qubits based on the formation of quantum dots ensuring the confinement of elementary charges (electrons or holes). In these devices, the quantum information is, for example, coded on the spin of these particles. The quantum dots are formed by means of grids via which electrical confinement potentials are created in a semiconductor material. These grids make it possible to locally adjust the electrostatic potential of the quantum dots, i.e. the depth of the potential wells of the quantum dots. These devices may also comprise other grids electrically controlling the tunnel coupling, i.e. the height of the tunnel barriers, between neighboring quantum dots.

[0003] In practice, electrically charged defects are present in materials, for example at the Si-SiO2 interfaces of quantum dots, and locally disturb the electrostatic potential of the quantum dots and tunnel barriers. The electrostatic disorder generated by these defects is superimposed on the electrostatic potentials generated by the gates.

[0004] One way to reduce the impact of this electrostatic disorder is to reduce the pitch with which the grids are made, that is to say to reduce the length and the spacing between two neighboring grids, so that this pitch is lower than the characteristic length of the disorder to be able to compensate for it or to work on a smaller scale than this disorder. Nevertheless, the pitch achievable with the available lithography tools remains insufficient to correctly compensate for the impact of electrically charged defects.

[0005] Document WO 2019 / 125348 A1 describes a quantum device in which the network of qubits is vertically integrated. Such a configuration makes it possible to reduce the achievable pitch compared to devices in which the grids are all arranged in the same plane. Summary of the invention

[0006] An electronic device is proposed which does not have one or more of the drawbacks previously described, and which makes it possible to obtain pitch values ​​which cannot be achieved by the known structures described above.

[0007] One embodiment proposes a solution to all or part of the drawbacks of the known solutions and proposes an electronic device comprising:

[0008] - a support;

[0009] - a semiconductor fin arranged on an upper face of the support, in which quantum dots are intended to be formed, and comprising a first side face and a second side face opposite the first side face

[0010] - several first control grids separate from each other, arranged in the side of the first lateral face, one above the other in a direction perpendicular to the upper face of the support and defining different grid levels, configured to each control the electrostatic potential of one of the quantum dots, the first control grid closest to the support being arranged in a grid level N, and the first control grid furthest from the support being arranged in a grid level N+Z, with N corresponding to an integer greater than or equal to 1, and Z corresponding to an integer greater than or equal to 2;

[0011] - at least one second control grid arranged on the side of the second face lateral, and configured to control the electrostatic potential of a coupling region intended to be formed between the quantum dots;

[0012] wherein said at least one second control grid is offset, in the direction perpendicular to the upper face of the support, relative to the first control grids and defines a grid level interposed between two other grid levels each comprising one of the first control grids.

[0013] According to a particular embodiment, a first part of the upper face of the support on which the first control grids are arranged is offset, in the direction perpendicular to the upper face of the support, relative to a second part of the upper face of the support on which the second control grid is arranged.

[0014] According to a particular embodiment, the device further comprises at least one first dielectric portion arranged between the first control grids.

[0015] According to a particular embodiment, the device comprises several second control grids arranged on the side of the second lateral face one above the other in the direction perpendicular to the upper face of the support and defining different grid levels, each configured to control the electrostatic potential of a coupling region intended to be formed between two of the quantum boxes,

[0016] and the second control grids are offset, in the direction perpendicular to the upper face of the support, relative to the first control grids control, each of the second control grids being arranged in a grid level interposed between two other grid levels each comprising one of the first control grids.

[0017] According to a particular embodiment, the device further comprises several first dielectric portions arranged between the first control grids and several second dielectric portions arranged between the second control grids.

[0018] According to a particular embodiment, in a direction perpendicular to the lateral faces, each of the first control grids has a width different from those of the other first control grids and each of the second control grids has a width different from those of the other second control grids.

[0019] According to a particular embodiment, a dimension of the semiconductor fin perpendicular to the first and second lateral faces is such that a single plane or two planes of quantum dots parallel to the first and second lateral faces are intended to be formed in the semiconductor fin.

[0020] According to a particular embodiment, heights, in the direction perpendicular to the upper face of the support, of the first and second control grids are equal to each other.

[0021] According to a particular embodiment, in a plane perpendicular to the upper face of the support and perpendicular to the first and second lateral faces, the first and second control grids are aligned with respect to each other, or the first control grids are offset with respect to the second control grids.

[0022] According to a particular embodiment, the device comprises several distinct sets of first and second control gates arranged along a length of the semiconductor fin which corresponds to a dimension parallel to the first and second lateral faces and to the upper face of the support.

[0023] A method of producing an electronic device is also proposed, comprising:

[0024] - production of a semiconductor fin on an upper face of the support, in which quantum dots are intended to be formed, and comprising a first side face and a second side face opposite the first side face

[0025] - production of several first control grids separate from each other others, arranged on the side of the first lateral face, one above the other in a direction perpendicular to the upper face of the support and defining different grid levels, each configured to control the electro potential static of one of the quantum boxes, the first control grid closest to the support being arranged in a grid level N, and the first control grid furthest from the support being arranged in a grid level N+Z, with N corresponding to an integer greater than or equal to 1, and Z corresponding to an integer greater than or equal to 2;

[0026] - production of at least one second control grid arranged on the side of the second side face, and configured to control the electrostatic potential of a coupling region intended to be formed between the quantum dots;

[0027] wherein said at least one second control grid is offset, in the direction perpendicular to the upper face of the support, relative to the first control grids and defines a grid level interposed between two other grid levels each comprising one of the first control grids.

[0028] According to a particular embodiment, the production of the semiconductor fin comprises at least one etching of the support, and the first and second control gates are then produced on remaining parts of the support arranged on either side of the semiconductor fin.

[0029] According to a particular embodiment, the production of the semiconductor fin comprises at least one epitaxial growth from a region of the support forming a bottom wall of an opening formed through a stack of layers arranged on the support and from which the first and second control gates are produced.

[0030] According to a particular embodiment, the production of the first and second control grids comprises at least the implementation of the following steps:

[0031] - production of a stack of layers of a first semiconductor and layers of a second semiconductor arranged alternately above each other, the first and second semiconductors being capable of being selectively etched relative to each other;

[0032] - etching the stack such that at least two remaining portions of the stack are each arranged against one of the first and second side walls;

[0033] - selective removal of remaining parts of the layers of the second semiconductor present in the remaining portions of the stack;

[0034] - deposition of at least one dielectric material in spaces formed by the shrinkage selective of the remaining parts of the layers of the second semiconductor, forming first dielectric portions arranged between the first control gates and second dielectric portions arranged between several second control gates;

[0035] and the semiconductor fin is made before stacking.

[0036] According to a particular embodiment, the production of the first and second control grids comprises at least the implementation of the following steps:

[0037] - production of a stack of layers of an electrically conductive material and of layers of a dielectric material arranged alternately one above the other;

[0038] - etching the stack such that at least two remaining portions of the stack are each arranged against one of the first and second side walls;

[0039] and the stacking of layers is carried out after the semiconductor fin and by implementing successive steps of depositing the layers of electrically conductive material and the layers of dielectric material and, between the deposition steps, steps of removing parts of the layers of electrically conductive material and the layers of dielectric material deposited against the first and second lateral faces.

[0040] According to a particular embodiment, the production of the first and second control grids comprises at least the implementation of the following steps:

[0041] - production of a stack of layers of an electrically conductive material and of layers of a dielectric material arranged alternately one above the other;

[0042] - etching the stack such that at least two remaining portions of the stack of layers are each disposed against one of the first and second side walls;

[0043] and the semiconductor fin is made after stacking. Brief description of the drawings

[0044] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0045] - [Fig.l] represents an example of an electronic device according to a mode of realization particular lization;

[0046] - [Fig.2], [Fig.3], [Fig.4], [Fig.5], [Fig.6], [Fig.7], [Fig.8], [Fig.9], [Fig.10], [Fig.11], [Fig.12], [Fig.13], [Fig.14], [Fig.15], [Fig.16], [Fig.17], [Fig.18], [Fig.19], [Fig.20], [Fig.21], [Fig.22], [Fig.23] and [Fig.24] represent steps of a method of producing an electronic device according to a particular embodiment;

[0047] - [Fig.25], [Fig.26], [Fig.27] and [Fig.28] represent stages of a variant of a method of producing an electronic device according to a particular embodiment. Description of the embodiments

[0048] 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.

[0049] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed.

[0050] 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.

[0051] 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", "lateral", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made unless otherwise specified to the orientation of the figures. However, these terms do not presume the actual position and orientation of the device during its use.

[0052] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0053] An example of an electronic device 100 according to a particular embodiment is described below in connection with [Fig.l] which is a sectional view of the device 100.

[0054] In the exemplary embodiment described, the device 100 comprises at least one support 102 on which at least one semiconductor fin 104 (called a “fin” in English) is arranged. According to a particular embodiment of the device 100, the fin 104 may correspond to a portion of a surface semiconductor layer of a substrate of the semiconductor-on-insulator type, for example SOI (“Silicon On Insulator”). The support 102, in this case, may correspond to the stack comprising the buried dielectric layer arranged on the bulk semiconductor layer of the semiconductor-on-insulator type substrate. The buried dielectric layer corresponds for example to a layer of SiO2 and the bulk layer comprises for example silicon.

[0055] For example, the fin 104 may comprise silicon when the qubits intended to be used in the device 100 correspond to electron qubits. Alternatively, the fin 104 may comprise, for example, germanium when the qubits intended to be used in the device 100 correspond to hole qubits.

[0056] Alternatively, the fin 104 may not correspond to a portion of a surface layer of a semiconductor-on-insulator type substrate, and may be formed, for example by deposition or any other suitable technique, on or from another type of support. 102 corresponding for example to a bulk or solid substrate which may comprise a semiconductor such as a semiconductor wafer.

[0057] In the embodiment described, a width W of the fin 104, corresponding to the dimension parallel to the Y axis visible in [Fig.l], is for example between 10 nm and 50 nm. A thickness H of the fin 104, corresponding to the dimension parallel to the Z axis visible in [Fig.l], is for example between 100 nm and 1 pm. The value chosen for this thickness is in particular a function of the number of gate levels of the device 100 intended to be superimposed on top of each other, and therefore of the number of quantum dots and any charge detectors and carrier reservoirs intended to be formed in the fin 104. Finally, a length L of the fin 104, corresponding to the dimension parallel to the X axis visible in [Fig.l], is for example between 500 nm and 10 pm.

[0058] In this exemplary embodiment, the device 100 comprises at least two first control grids 106 separate from each other, arranged one above the other, and each covering a portion of a first lateral face 108 of the fin 104 (face parallel to the plane (X,Z) in [Fig.l]). The first grids 106 are configured to each control the electrostatic potential of one of the quantum dots intended to be formed in the fin 104 and to be subjected to the electrostatic control of the first grids 106, this electrostatic control being obtained via the electrical potential intended to be applied to each of these first grids 106. Each of the first grids 106 comprises at least one electrically conductive portion. The first grids 106 define different grid levels called first grid levels.The first grid 106 closest to the support 102 is arranged in a grid level N, and the first grid 106 furthest from the support 102 is arranged in a grid level N+Z, with N corresponding to an integer greater than or equal to 1, and Z corresponding to an integer greater than or equal to 2.

[0059] In the example of [Fig.l], the device 100 comprises more than two first grids 106. The device 100 however comprises a number of first grids 106 which is a function of the number of quantum boxes intended to be formed in the fin 104.

[0060] In a particular configuration of the device 100, each of the first grids 106 may comprise at least one electrically conductive material such as doped monocrystalline silicon and / or silicide, or polysilicon, or a stack of several materials.

[0061] In a particular configuration of the device 100, each of the first grids 106 has a length LGi (dimension parallel to the length L of the fin 104) for example between 15 nm and 50 nm, and a height HGi (dimension parallel to the height H of the fin 104) for example between 5 nm and 15 nm. The height H gi of the first grids 106 depends in particular on the material(s) used to form these first grids 106 as well as the technique(s) implemented to form these first grids 106.

[0062] In the exemplary embodiment of the device 100 described and shown in [Fig. 1], each of the first grids 106 comprises, along an axis perpendicular to the first lateral face 108, a width WGi different from those of the other first grids 106. As can be seen in [Fig. 1], the values ​​of the widths WGi of the first grids 106 decrease in the direction from the base of the fin 104 arranged against the support 102 to the top of the fin 104 (direction parallel to the axis Z visible in [Fig. 1]). Thus, the end of each of the first grids 106 is not arranged opposite one or more of the other first grids 106 located above this first grid 106. These ends can therefore serve as electrical access to each of the first grids 106. In the example of [Fig.l], these electrical accesses to the first grids 106 are made by first electrical contacts 110 each electrically coupled to the end of one of the first grids 106. The first electrical contacts 110 comprise for example at least one metallic material such as Ti, TiN or W.

[0063] In a particular configuration of the device 100, each of the first gates 106 is electrically insulated from the neighboring first gate(s) 106 (located above and / or below the first gate 106 in question) by first dielectric portions 112 interposed between them. Thus, two neighboring first gates 106 arranged one above the other are spaced apart from each other by a distance equal to the thickness (dimension parallel to the height H of the fin 104) of one of the first dielectric portions 112 which is for example between 5 nm and 15 nm. The first dielectric portions 112 comprise for example SiO2 or any other dielectric material suitable for electrically insulating the neighboring first gates 106 from each other.

[0064] In the exemplary embodiment described, the device 100 comprises at least one second control grid 114 covering a portion of a second lateral face 116, opposite the first lateral face 108, of the fin 104. In [Fig.l], this second lateral face 116 is parallel to the plane (X,Z). The second grid 114 is configured to control the electrostatic potential of a coupling region intended to be formed in the fin 104 between two quantum dots and to be subjected to the electrostatic control of the second grid 114, this electrostatic control being obtained via the electrical potential intended to be applied to the second grid 114. The second grid 114 comprises at least one electrically conductive portion. The second grid 114 defines a grid level called the second grid level and which is interposed between two other first grid levels each comprising one of the first grids 106.

[0065] In the example of [Fig.l], the device 100 comprises several second grids 114. The device 100 however comprises a number of second grids 114 which is a function of the number of coupling regions intended to be controlled in the fin 104. Each of the second grids 114 is arranged in a second grid level interposed between two other first grid levels each comprising one of the first grids 106.

[0066] In a particular configuration of the device 100, each of the second grids 114 may comprise at least one electrically conductive material such as doped monocrystalline silicon and / or silicide, or polysilicon, or a stack of several materials. In an advantageous configuration, the material(s) of the second grids 114 are similar to that(s) of the first grids 106.

[0067] In a particular configuration of the device 100, each of the second grids 114 has a length LG2 (dimension parallel to the length L of the fin 104) for example between 15 nm and 50 nm and which is for example equal to the length LGi. In addition, each of the second grids 114 may have a height HG2 (dimension parallel to the height H of the fin 104) for example between 5 nm and 15 nm and which is for example equal to the height HGi. The height HG2 of the second grids 114 depends in particular on the material(s) used to form these second grids 114 as well as the technique(s) implemented to form these second grids 114.

[0068] In the embodiment described, as for the first grids 106, each of the second grids 114 comprises, along an axis perpendicular to the second lateral face 116, a width WG2 different from those of the other second grids 114. As can be seen in [Fig. 1], the values ​​of the widths WG2 of the second grids 114 decrease in the direction from the base of the fin 104 arranged against the support 102 to the top of the fin 104 (direction parallel to the axis Z visible in [Fig. 1]). Thus, the end of each of the second grids 114 is not arranged opposite one or more of the other second grids 114 located above this second grid 114. These ends can therefore serve as electrical access to each of the second grids 114. In the example of [Fig.l], these electrical accesses to the second grids 114 are made by second electrical contacts 118 each electrically coupled to the end of one of the second grids 114. The second electrical contacts 118 comprise for example at least one metallic material such as Ti, TiN, or W, and comprise for example the same material(s) as those forming the first electrical contacts 110.

[0069] In a particular configuration of the device 100, each of the second grids 114 is electrically isolated from the neighboring second grid(s) 114 (located above and / or below the second grid 114 considered) by second dielectric portions 120 interposed between them. Thus, two second grids 114 neighboring and arranged one above the other are spaced from each other by a distance equal to the thickness (dimension parallel to the height H of the fin 104) of one of the second dielectric portions 120 which is for example between 5 nm and 15 nm and which is for example equal to the thickness of one of the first dielectric portions 112. The second dielectric portions 120 comprise for example SiO2 or any other dielectric material suitable for electrically insulating the second grids 114 neighboring one from the other. The second dielectric portions 120 advantageously comprise the same or the same dielectric materials as those forming the first dielectric portions 112.

[0070] In the device 100, the first grids 106 are not aligned, in a plane parallel to their width WGi and to their length LGi (plane parallel to the plane (X,Y) in [Fig.l]), with the second grids 114, that is to say are not arranged entirely, or totally, opposite the first grids 106. In other words, at least a part of the orthogonal projections of the parts of the second lateral face 116 covered by the second grids 114 on the first lateral face 108 are arranged between the parts of the first lateral face 108 covered by the first grids 106. Advantageously, the first and second grids 106, 114 are arranged alternately in different grid levels along the dimension parallel to the thickness H of the fin 104, that is to say along the axis Z.In other words, the first grid levels and the second grid levels are arranged alternately along the dimension parallel to the thickness H of the fin 104.

[0071] In the embodiment described, this offset between the first grids 106 and the second grids 114 is the consequence of the fact that a first part 122 of an upper face of the support 102 (on which the first grids 106 are arranged) is arranged in a plane different from that in which a second part 124 of the upper face of the support 102 is arranged (on which the second grids 114 are arranged). The difference in height (dimension parallel to the Z axis) between the first and second parts 122, 124 of the upper face of the support 102 is for example equal to the thickness of one of the first and second dielectric portions 112, 120 and which corresponds for example to the thickness HGi, HG2 of one of the first or second grids 106, 114. In the embodiment shown in [Fig.l], the thickness of the part of the support 102 including the first part 122 of its upper face is greater than that including the second part 124 of its upper face. Alternatively, it is possible that the thickness of the part of the support 102 including the first part 122 of its upper face is smaller than that including the second part 124 of its upper face.

[0072] Alternatively, it is possible that the offset between the first grids 106 and the second grids 114, parallel to their height, is due not to a difference in height between the first and second parts 122, 124 of the upper face of the support 102, but to a portion of additional material present only on one of these first and second parts 122, 124 of the upper face of the support 102 and on which the first grids 106 or the second grids 114 are produced.

[0073] In the embodiment shown in [Fig.l], the orthogonal projections of the parts of the second lateral face 116 covered by the second grids 114 on the first lateral face 108 are arranged between the parts of the first lateral face 108 covered by the first grids 106, without overlap between these projected parts of the second lateral face 116 and those of the first lateral face 108 covered by the first grids 106. As a variant, it is possible to have a partial overlap of the projected parts of the second lateral face 116 and those of the first lateral face 108 covered by the first grids 106.For example, this partial covering may be such that at most, half of the surface of each of the orthogonal projections of the parts of the second lateral face 116 covered by the second grids 114 on the first lateral face 108 covers one of the parts of the first lateral face 108 covered by the first grids 106.

[0074] In the embodiment of the device 100 described, the lateral faces 108, 116 of the fin 104 are covered with a dielectric layer 126 intended to serve in particular as gate oxide for the first gates 106 and the second gates 114. The dielectric layer 126 comprises for example SiO2 and / or Al2O3 and / or HfO2. The thickness of the dielectric layer 126 is for example between 2 nm and 20 nm.

[0075] In the remainder of the description, reference is made to several second control grids 114 of the device 100. Nevertheless, the various characteristics described in connection with the second control grids 114 would also apply to the single second control grid 114 of the device 100 if the device 100 only included a single second control grid 114.

[0076] During operation of the device 100, an electrical potential, for example between 50 mV and 150 mV, can be applied to the first grids 106 to create the quantum dots in the fin 104. The second grids 116 are used to couple or decouple the qubits from the quantum dots 114 as required, by applying electrical potentials to them, for example between - 3 V and + 3 V, generating an attractive or repulsive effect, of positive or negative value.

[0077] The device 100 may further comprise several third grids 128 separate from one another, arranged under the first and second grids 106, 114 and each covering a part of one of the first and second lateral faces 108, 116. In a particular configuration, it is possible to have several third disjointed grids 128, superimposed on one another and arranged under the first grids 106, as well as other third disjointed grids 128, superimposed on one another and arranged under the second grids 114. The third grids 128 comprise for example a length (dimension parallel to the length (dimension parallel to the length L of the fin 104) and a height (dimension parallel to the height H of the fin 104) for example similar to those of the first grids 106 and / or the second grids 114. The material(s) of these third grids 128 are for example similar to those of the first grids 106 and / or the second grids 114. The third grids 128 are here arranged in grid levels lower than, or below, those comprising the first and second grids 106, 114.

[0078] The device 100 may further comprise several fourth grids 130 disjointed from one another, arranged above the first and second grids 106, 114 and each covering a portion of one of the first and second lateral faces 108, 116. In a particular configuration, it is possible to have several fourth disjointed grids 130, superimposed on one another and arranged above the first grids 106, as well as other fourth disjointed grids 130, superimposed on one another and arranged above the second grids 114. The fourth grids 130 comprise for example a length (dimension parallel to the length (dimension parallel to the length L of the fin 104) and a height (dimension parallel to the height H of the fin 104) for example similar to those of the first grids 106 and / or second grids 114.The material(s) of these fourth grids 130 are for example similar to those of the first grids 106 and / or the second grids 114. The fourth grids 130 are here arranged in grid levels higher than, or above, those comprising the first and second grids 106, 114.

[0079] The third and fourth grids 128, 130 arranged on the same side as the first grids 106, that is to say those each covering a part of the first lateral face 108, can be used to control the electrostatic potentials of charge detectors formed in parts of the fin 104 between which the quantum dots are intended to be formed and / or serve as current feeds from carrier reservoirs to the charge detectors and / or quantum dots.

[0080] The third and fourth grids 128, 130 arranged on the same side as the second grids 114, i.e. those each covering a part of the second lateral face 116, can be used to control the coupling regions between the charge detectors and the quantum dots and / or the coupling regions between the current leads and the charge detectors or between the current leads and the boxes quantum.

[0081] The height offset previously described between the first grids 106 and the second grids 114 can also be found between the third grids 128 located on either side of the fin 104 and also between the fourth grids 130 located on either side of the fin 104. Furthermore, when the device 100 comprises the third grids 128 and the fourth grids 130, first dielectric portions 112 and second dielectric portions 120 are also arranged between the neighboring third grids 128, between the third grids 128 and the other grids neighboring them, between the neighboring fourth grids 130, and between the fourth grids 130 and the other grids neighboring them. The electrical contacts of the third and fourth grids 128, 130 can also be provided by electrical contacts similar to the first and second electrical contacts 110, 118.

[0082] In the exemplary embodiment described, the device 100 also comprises a dielectric encapsulation material 132 covering the stack of grids 106, 114, 128, 130, the fin 104 and the parts of the support 102 not covered by the grids. In the presence of such a dielectric encapsulation material 132, the electrical contacts 110, 118 can be made through this dielectric encapsulation material 132. This dielectric encapsulation material 132 corresponds for example to SiO2.

[0083] This particular pattern of the gates 106, 114 may be repeated, for example periodically, thus forming several distinct sets of first and second control gates 106, 114 arranged along the length of the fin 104 (dimension parallel to the X axis), thus multiplying the number of qubits that can be formed in the fin 104.

[0084] In the examples previously described, the first grids 106 and the second grids 114 are aligned with each other, considering a plane parallel to the plane (Y, Z), that is to say a plane which is both perpendicular to the upper face of the support 102 and to the first and second lateral faces 108, 116 of the fin 104. As a variant, it is possible to have an offset, along the axis X, of the first grids 106 relative to the second grids 114.

[0085] An example of a method for producing the electronic device 100 is described below in connection with figures 2 to 24. In each of figures 2 to 22, view a) corresponds to a perspective view of the structure produced, and view b) corresponds to a sectional view of the structure produced, this sectional view being taken along an axis (AA) for figures 2 to 15, 17 to 20 and 22, and along an axis (BB) for figures 16 and 21. Figures 23 and 24 correspond to sectional views taken along the axis AA.

[0086] In this example, the fin 104 is first produced. In the example described, the fin 104 is produced from the support 102 which corresponds to a solid substrate of semiconductor, for example silicon or germanium (see [Fig.2]).

[0087] To produce the fin 104, a hard mask layer 134, comprising for example SiN, is deposited on the support 102 (see [Fig. 3]). This layer 134 is then etched according to the desired pattern for the fin 104. In the example of [Fig. 3], a lithography resin 136 is formed on the layer 134 according to the desired pattern for the fin 104.

[0088] The hard mask obtained at the end of this etching is designated by the reference 138 and visible in [Fig. 4]. Optionally, an oxidation of the semiconductor surface of the support 102 can be implemented. In the example of [Fig. 4], this oxidation forms a layer 140 of semiconductor oxide, for example SiO2 when the support 102 comprises silicon.

[0089] The support 102 is then etched so that the first part 122 of the upper face of the support 102 is arranged in a plane different from that in which the second part 124 of the upper face of the support 102 is arranged. For this, lithography is carried out using a resin 142 masking the hard mask 138 and the part of the support 102 (and therefore also of the layer 140 if an oxidation of the support 102 has been previously carried out) intended to be thicker than the other, that is to say that intended to include the first part 122 of the upper face of the support 102 (see [Fig.5]).

[0090] The part of the support 102 (and possibly of the layer 140 if the latter is present) not covered by the resin 142 is then partially etched in order to obtain the desired height difference subsequently between the first and second parts 122, 124 of the upper face of the support 102. The resin 142 is then removed (see [Fig.6]).

[0091] The production of the fin 104 is then completed by implementing an etching of the support 102 (and possibly of the remaining part of the layer 140 previously covered by the resin 142 if the latter is present). The part of the support 102 covered by the hard mask 138 is protected from this etching and forms the fin 104. This etching is stopped when the desired height H of the fin 104 is obtained. This etching also forms the first and second parts 122, 124 of the upper face of the support 102 on which the first and second grids 106, 114 will be produced. The structure obtained at this stage of the process is shown in [Fig.7].

[0092] Alternatively, the fin 104 can be produced by etching the surface layer of a substrate SOL. Other variants can also be implemented to form the fin 104 on the support 102.

[0093] In the example described, carrier reservoirs are then produced, for example by masking the regions of the support 102 and the fin 104 in which the carrier reservoirs are not produced and by implementing an implantation of dopants. in the unmasked regions. In [Fig. 8], the regions of the upper face of the support 102 through which the dopants are implanted are designated by the reference 144, and the carrier reservoirs produced correspond to the regions of the fin 104 in which the dopants are implanted, these reservoirs being designated by the reference 146. In the example described, these carrier reservoirs 146 are produced in the ends of the fin 104. For simplification, the doped regions 144 of the support 102 and the carrier reservoirs 146 formed in the fin 104 are no longer shown in Figures 9 and following.

[0094] The dielectric layer 126 is then produced. The dielectric material can be formed on the entire structure produced, in the form of a conformal deposit (thickness substantially constant on all the walls against which the dielectric material is deposited) as can be seen in [Fig. 8]. Alternatively, it is possible to form this dielectric layer 126 by implementing thermal oxidation of the semiconductor of the fin 104 and the other accessible parts of the support 102, in particular the parts 122, 124 of the upper face of the support 102. When such thermal oxidation is implemented, the dielectric layer is not formed against the walls of the hard mask 138. The implementation of such thermal oxidation with a support 102 and a fin 104 comprising silicon forms a dielectric layer 126 comprising SiO2.

[0095] The parts of the dielectric layer 126 which do not cover the side walls 108, 116 of the fin 104 are then removed, in particular the parts of the dielectric layer 126 located on the parts 122, 124 of the upper face of the support 102 and possibly the part of the dielectric layer 126 located on the top of the fin 104 (see [Fig.9]). The removal of these parts of the dielectric layer 126 is for example obtained by implementing anisotropic etching of the dielectric layer 126.

[0096] The first and second grids 106, 114 are then produced such that each covers a portion of one of the lateral faces 108, 116 of the fin 104. To produce these grids, the following steps are for example implemented.

[0097] A stack of layers of a first semiconductor 148 and layers of a second semiconductor 150 arranged alternately one above the other is produced on the parts 122, 124 of the upper face of the support 102, that is to say on either side of the fin 104 and against the dielectric layer 126 formed against the lateral faces 108, 116 of the fin 104 (see [Fig. 10]). The first and second semiconductors are chosen such that they are capable of being selectively etched relative to each other. For example, the thickness of each of the layers 148, 150 may be between 5 nm and 15 nm. Such a stack of layers 148, 150 may be produced by implementing successive steps epitaxy. According to an advantageous embodiment, the layers 148 may comprise silicon and the layers 150 may comprise SiGe.

[0098] The stack produced is then etched according to the desired geometry for the first and second grids 106, 114.

[0099] For this, a hard mask layer 152 is deposited on the structure produced, i.e. on the stack of layers 148, 150 and on the hard mask 138. A chemical-mechanical planarization, or CMP, is then implemented with stopping on the hard mask 138 (see [Fig. 11]).

[0100] Lithography is then carried out so as to transfer the desired pattern of the first and second grids 106, 114 into the hard mask layer 152, then the hard mask layer 152 is etched according to this pattern, the remaining parts of the hard mask layer 152 covering the portions of the stack of layers 148, 150 intended for the production of the first and second grids 106, 114. As can be seen in [Fig. 12], the remaining parts of the hard mask layer 152 arranged on the side of the first lateral face 108 of the fin 104 and defining the pattern of the first grids 106 are arranged opposite those arranged on the side of the second lateral face 116 of the fin 104 and which define the pattern of the second grids 114.

[0101] The stack of layers is then etched according to the pattern defined by the remaining parts of the hard mask layer 152, this etching being stopped when the support 102 is reached. The hard mask 138 is also removed, for example by etching (see [Fig. 13]).

[0102] Optionally, an implantation step may be implemented in order to form one or more other carrier reservoirs 154 in an upper portion of the fin 104. According to a first example, a carrier reservoir 154 may be produced in an upper and central portion of the fin 104, as shown in [Fig. 14]. According to a second example, several distinct carrier reservoirs 154 may be produced in an upper portion of the fin 104, and aligned in a direction parallel to the length of the fin 104 (parallel to the X axis). This or these other carrier reservoirs 154 may be obtained by implementing a masking step then a dopant implantation step, as for the production of the carrier reservoirs 146 previously described. For simplification, this other carrier reservoir 154 is only shown in [Fig. 14] and not on the following figures.

[0103] An encapsulation layer 156 comprising for example oxide such as SiO2 is then deposited so as to encapsulate the unetched portions of the stack of layers 148, 150. The material of this encapsulation layer is in particular deposited around and between the unetched portions of the stack. A CMP can then be implemented until the desired thickness is reached for the layer. encapsulation 156 (see [Fig. 14]).

[0104] In the example described, the remaining portions of the hard mask layer 152 may be retained during the deposition of the encapsulation layer 156, for example when the materials of the hard mask layer 152 and the encapsulation layer 156 are identical. Alternatively, and in particular when the materials of the hard mask layer 152 and the encapsulation layer 156 are not identical, the remaining portions of the hard mask layer 152 may be removed before the deposition of the encapsulation layer 156.

[0105] In order to facilitate the removal of the layers of the second semiconductor 150, a mechanical holding structure can be produced on the stack of layers.

[0106] To produce this structure, another hard mask layer 158 is deposited on the structure produced at this stage (see [Fig. 15]). Lithography is then carried out and the hard mask layer 158 is etched according to the pattern defined by this lithography (see [Fig. 16]).

[0107] The encapsulation layer 156 is then etched according to the pattern of the hard mask layer 158 (see [Fig. 17]).

[0108] The layers of the second semiconductor 150 are then removed, for example by selective etching with respect to the other materials present, in particular with respect to the layers of the first semiconductor 148 (see [Fig. 18]). The presence of the remaining portions of the encapsulation layer 156 makes it possible to ensure the mechanical maintenance of the layers of the first semiconductor 148.

[0109] The hard mask layer 158 is then removed (see [Fig. 19]).

[0110] Views b) of Figures 17 to 19 are such that the cutting axis AA does not pass through the remaining portions of the layers of the first and second semiconductors 148, 150.

[0111] A conformal deposition of dielectric material on the entire structure is then implemented, forming in particular the first dielectric portions 112 and the second dielectric portions 120 between the layers of the first semiconductor 148 (see [Fig.20]). The deposited dielectric material corresponds for example to SiO2.

[0112] Partial etching of the deposited dielectric material is then carried out, in particular to remove the portions of this dielectric material covering the upper faces and the lateral sides of the stacks comprising the parts of the layer of the first semiconductor 148 and the first and second dielectric portions 112, 120. The structure obtained at this stage is shown in [Fig.21].

[0113] A siliciding of the layers of the first semiconductor 148 can then be implemented (see [Fig.22]).

[0114] An etching of the layers of the first semiconductor 148, of the first dielectric portions 112 and of the second dielectric portions 120 can then be implemented so that one of their ends is revealed and forms electrical accesses. to each of these elements. This engraving completes the production of the first and second 106, 114, as well as that of the third and fourth grids 128, 130 (see [Fig.23]).

[0115] The dielectric encapsulation material 132 can then be deposited so as to cover the entire structure produced (see [Fig.24]).

[0116] The device 100 can then be completed by making the first and second electrical contacts 110, 118 as well as those electrically connected to the third and fourth grids 128, 130, these contacts being able to be made through the dielectric encapsulation material 132, for example by etching the dielectric encapsulation material 132 then filling the holes etched in the dielectric encapsulation material 132 with one or more electrically conductive materials. The device 100 obtained corresponds to the outcome of this method corresponds to that previously described in connection with [Fig.l].

[0117] In the method described above, the different gates 106, 114, 128, 130 are produced by firstly forming a stack of alternating layers which can be selectively etched relative to each other (for example a stack of Si / SiGe type) then by selectively etching the layers of one of the two materials and by filling the spaces obtained with a dielectric material to form the first and second dielectric portions 112, 120.

[0118] Alternatively, it is possible to directly produce a stack comprising alternately layers of electrically conductive material(s), for example in-situ doped polysilicon (amorphous or not) and / or one or more metallic materials, and layers of dielectric material, for example SiO2. In this case, it is not necessary to produce the mechanical holding structure or the various steps previously described making it possible to replace the layers of the second semiconductor 150 with the first and second dielectric portions 112, 120. In this alternative, it is however appropriate to ensure that the successive deposits implemented do not leave residual layers against the lateral faces 108, 116 of the fin 104. If the deposits implemented leave such residual layers on the sides of the fin 104, steps of etching these residual layers can be implemented between the deposition steps.In this case, it is possible to deposit, after each deposition of layers of the stack, a planarizing layer of the SOC type, then to etch the residual layer present on the sides of the fin 104 and not covered by the planarizing layer. Alternatively to the use of a planarizing layer, it is possible to implement a CMP then to carry out a partial removal of the deposited material to remove the residual layer.

[0119] According to another alternative, in order to overcome the problems linked to the possible presence of residual layers against the side walls of the fin 104, it is possible to produce the stacking of layers of electrically conductive material and layers of dielectric material prior to the production of the fin 104. [Fig.25] represents such a stacking in which the reference 160 designates the layers of electrically conductive material and the reference 162 designates the layers of dielectric material.

[0120] An etching is then carried out through this stack of layers 160, 162, in order to form an opening 164 for the fin 104 ([Fig.26]). The etched opening corresponds for example to a trench.

[0121] The dielectric layer 126 can then be deposited against the sides of the opening 164 (see [Fig.27]).

[0122] The fin 104 can then be produced in the remaining space of the opening 164, for example by implementing epitaxy from the bottom wall of the opening 164 formed by the support 102 (see [Fig.28]).

[0123] In the various embodiments and variants of the device 100 described, the arrangement of the first and second grids 106, 114 in the form of a vertical stack with an offset between the first and second grids 106, 114 makes it possible to significantly reduce the value of the pitch achievable between the control grids of the quantum dots, and thus to obtain, in the semiconductor fin, a very high density of quantum dots while allowing good compensation for the impact of the electrically charged defects present in the materials of the device 100.

[0124] In the various embodiments and variants of the device 100 previously described, a dimension of the semiconductor fin 104 perpendicular to the first and second lateral faces 108, 116 (dimension parallel to the Y axis in the various figures) is such that a single plane or two planes of quantum dots parallel to the first and second lateral faces 108, 116 (i.e. parallel to the (X,Y) plane) are intended to be formed in the semiconductor fin 104.

[0125] 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.

[0126] Finally, the practical implementation of the embodiments and variants described is within the reach of the person skilled in the art from the indications given above. For example, the nature (wet, dry, etc.) of each of the engravings implemented can be chosen in particular depending on the material(s) to be engraved.

Claims

Claims

1. Electronic device (100) comprising: - a support (102); - a semiconductor fin (104) arranged on an upper face of the support (102), in which quantum dots are intended to be formed, and comprising a first lateral face (108) and a second lateral face (116) opposite the first lateral face (108); - several first control grids (106) disjointed from each other, arranged on the side of the first lateral face (108), one above the other in a direction perpendicular to the upper face of the support (102) and defining different grid levels, configured to each control the electrostatic potential of one of the quantum dots, the first control grid (106) closest to the support (102) being arranged in a grid level N, and the first control grid (106) furthest from the support (102) being arranged in a grid level N+Z, with N corresponding to an integer greater than or equal to 1, and Z corresponding to an integer greater than or equal to 2; - at least one second control grid (114) arranged on the side of the second lateral face (116), and configured to control the electrostatic potential of a coupling region intended to be formed between the quantum dots; wherein said at least one second control grid (114) is offset, in the direction perpendicular to the upper face of the support (102), relative to the first control grids (106) and defines a grid level interposed between two other grid levels each comprising one of the first control grids (106).

2. Electronic device (100) according to claim 1, wherein a first part (122) of the upper face of the support (102) on which the first control grids (106) are arranged is offset, in the direction perpendicular to the upper face of the support (102), relative to a second part (124) of the upper face of the support (102) on which the second control grid (114) is arranged.

3. Electronic device (100) according to one of the preceding claims, comprising several second control grids (114) arranged on the side of the second lateral face (116) one above the other in the direction perpendicular to the upper face of the support (102) and defining different grid levels, configured to each control the electrostatic potential of a coupling region intended to be formed between two of the quantum dots, in which the second control grids (114) are offset, in the direction perpendicular to the upper face of the support (102), relative to the first control grids (106), each of the second control grids (114) being arranged in a grid level interposed between two other grid levels each comprising one of the first control grids (106).

4. The electronic device (100) of claim 3, further comprising a plurality of first dielectric portions (112) disposed between the first control gates (106) and a plurality of second dielectric portions (120) disposed between the second control gates (114).

5. Electronic device (100) according to one of claims 3 or 4, wherein, in a direction perpendicular to the lateral faces (108, 116), each of the first control grids (106) has a width different from those of the other first control grids (106) and each of the second control grids (114) has a width different from those of the other second control grids (114).

6. An electronic device (100) according to one of the preceding claims, wherein a dimension of the semiconductor fin (104) perpendicular to the first and second side faces (108, 116) is such that a single plane or two planes of quantum dots parallel to the first and second side faces (108, 116) are intended to be formed in the semiconductor fin (104).

7. Electronic device (100) according to one of the preceding claims, wherein heights, in the direction perpendicular to the upper face of the support (102), of the first and second control grids (106, 114) are equal to each other.

8. Electronic device (100) according to one of the preceding claims, in which, in a plane perpendicular to the upper face of the support (102) and perpendicular to the first and second side faces (108, 116), the first and second control grids (106, 114) are aligned with each other, or the first control grids are offset with respect to the second control grids.

9. An electronic device (100) according to any preceding claim, comprising a plurality of distinct sets of first and second control gates (106, 114) disposed along a length of the semiconductor fin (104) that corresponds to a dimension parallel to the first and second side faces (108, 116) and the top face of the support (102).

10. Method for producing an electronic device (100), comprising: - producing a semiconductor fin (104) on an upper face of the support (102), in which quantum dots are intended to be formed, and comprising a first lateral face (108) and a second lateral face (116) opposite the first lateral face (108);- production of several first control grids (106) disjointed from each other, arranged on the side of the first lateral face (108), one above the other in a direction perpendicular to the upper face of the support (102) and defining different grid levels, configured to each control the electrostatic potential of one of the quantum dots, the first control grid (106) closest to the support (102) being arranged in a grid level N, and the first control grid (106) furthest from the support (102) being arranged in a grid level N+Z, with N corresponding to an integer greater than or equal to 1, and Z corresponding to an integer greater than or equal to 2;- production of at least one second control grid (114) arranged on the side of the second lateral face (116), and configured to control the electrostatic potential of a coupling region intended to be formed between the quantum boxes; wherein said at least one second control grid (114) is offset, in the direction perpendicular to the upper face of the support (102), relative to the first control grids (106) and defines a grid level interposed between two other grid levels each comprising one of the first control grids (106).

11. The method of claim 10, wherein the production of the semiconductor fin (104) comprises at least one etching of the support (102), and wherein the first and second control gates (106, 114) are then produced on remaining portions of the support (102) arranged on either side of the semiconductor fin (104).

12. The method of claim 10, wherein the production of the semiconductor fin (104) comprises at least one epitaxial growth from a region of the support (102) forming a bottom wall of an opening (164) formed through a stack of layers (160, 162) disposed on the support (102) and from which the first and second control gates (106, 114) are produced.

13. Method according to one of claims 10 or 11, wherein the production of the first and second control gates (106, 114) comprises at least the implementation of the following steps: - production of a stack of layers of a first semiconductor (148) and layers of a second semiconductor (150) arranged alternately one above the other, the first and second semiconductors being capable of being selectively etched relative to each other; - etching the stack such that at least two remaining portions of the stack are each arranged against one of the first and second side walls (108, 116); - selective removal of remaining parts of the layers of the second semiconductor (150) present in the remaining portions of the stack;- depositing at least one dielectric material in spaces formed by the selective removal of the remaining parts of the layers of the second semiconductor (150), forming first dielectric portions (112) arranged between the first control gates (106) and second dielectric portions (120) arranged between several second gates; control (114); and wherein the semiconductor fin (104) is made before stacking.

14. Method according to one of claims 10 or 11, in which the production of the first and second control grids (106, 114) comprises at least the implementation of the following steps: - production of a stack of layers of an electrically conductive material and layers of a dielectric material arranged alternately above each other; - etching the stack such that at least two remaining portions of the stack are each disposed against one of the first and second side walls (108, 116); wherein the stacking of layers is carried out after the semiconductor fin (104) and by implementing successive steps of depositing the layers of electrically conductive material and the layers of dielectric material and, between the deposition steps, steps of removing parts of the layers of electrically conductive material and the layers of dielectric material deposited against the first and second lateral faces (108, 116).

15. Method according to one of claims 10 or 11, in which the production of the first and second control grids (106, 114) comprises at least the implementation of the following steps: - production of a stack of layers of an electrically conductive material (160) and layers of a dielectric material (162) arranged alternately above each other; - etching the stack such that at least two remaining portions of the stack of layers are each arranged against one of the first and second side walls (108, 116); and wherein the semiconductor fin (104) is made after stacking.

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