Phase-shifting unit cell array for transmitter array antenna and manufacturing method therefor

Abstract

The invention relates to a transmitting and / or reflecting array antenna, intended to operate in sub-terahertz frequency bands. The present invention relates more particularly to a phase shift unit cell array 1 for a transmitting array antenna and its manufacturing method. The invention finds application, for example, in medical and industrial control imaging, Earth and deep space observation, as well as for radars and broadband telecommunications systems. The invention, according to each of its different aspects, may thus consist of, or result in, a first substrate 11 on which is fixed in pieces, or equivalently in blocks 12, a second substrate from which the pieces or blocks 12 have been cut. This relaxes the constraints of flatness of the assembly surfaces and / or reduces the risk of breakage of the substrates during their handling.

Description

DOMAINE TECHNIQUE

[0001] The present invention relates to a transmitting and / or reflecting array antenna, intended to operate in sub-terahertz frequency bands, for example of the order of one or several hundred gigahertz. The present invention relates more particularly to a phase shift unit cell array for a transmitting array antenna and its manufacturing method. The invention finds application, for example, in medical and industrial control imaging, Earth and deep space observation, as well as for radars and broadband telecommunications systems. ETAT DE LA TECHNIQUE

[0002] In reference to the figure 1 attached, a transmitting array antenna (or "transmit-array" in English) allows to focus or to form in the general case the radiation pattern of an excitation antenna called focal source. A phase law, and possibly amplitude, is generated on the surface of the transmitting array in order to transform the incident fields into a desired wavefront. Transmitting arrays are composed of several discrete elements called elementary or unit cells. They are generally square and allow by their number, their distribution and their phase and amplitude response to control the distribution of the radiated field. Each unit cell is composed of a receiving element or patch placed on the surface opposite the focal source and an emitting element or patch placed on the opposite surface.Phase shifts are applied to the unit cells, between the elements on the receiving and transmitting surfaces, to focus the incident wavefronts from the feed antenna. The primary focal source may be a horn (single source) or a compact antenna array. The transmitting array, in the form of a matrix of phase shift cells, is intended to form at least part of the antenna, or even a reconfigurable phased array antenna, with the associated primary feed.

[0003] Most antennas with a transmitting array at sub-THz frequencies are obtained today by implementing manufacturing processes that consist of transferring a first slice (or plate or wafer in English) of a substrate that can be made of glass, silicon or other materials used in microelectronics onto at least a second slice or plate or wafer of a substrate made of a material that can be identical or different from the first. Most of the time this assembly of substrates includes a metal layer on each of its 2 faces and at least one between the 2 substrates. Each of these layers can be etched to form patterns such as patches or radiating elements on the surfaces. The patches or radiating elements of one surface are considered as the receiving elements and those of the second surface as the transmitting elements.Each receiving element can optionally be connected to each emitting element by at least one metal via crossing the substrates to form an elementary phase shift cell.

[0004] For example, the following three scientific papers are based on this type of plate-to-plate assembly: S. Gharbieh, A. Clemente, J. Milbrandtand B. Reig, "Phase Change Material Based Reconfigurable Transmitarray: a Feasibility Study,"2022 16th European Conférence on Antennas and Propagation (EuCAP), Madrid, Spain, 2022, pp. 1-4, doi: 10.23919 / EuCAP53622.2022.9769642; H. -I. Kim, A. Wilcher, W. Lee, S. Nelson and Y. -K. Yoon, "Highly Energy Efficient 64-element Array Antenna Based on Cu / Co Metaconductor and Fused Silica," 2023 IEEE Wireless and Microwave Technology Conférence (WAMICON), Melbourne, FL, USA, 2023, pp. 137-139, doi: 10.1109 / WAMICON57636.2023.10124910; and R. Bowrothu, H. Kim, Y. K. Yoon and S. Schmidt, "3D Integrated Through Fused Silica Via (TFV) Based Array Antenna for mm Wave Communications," 2020 IEEE 70th Electronic Components and Technology Conférence (ECTC), Orlando, FL, USA, 2020, pp. 95-100, doi: 10.1109 / ECTC32862.2020.00028.

[0005] These solutions, like many other manufacturing methods, have the disadvantage of involving the handling of two relatively thin wafers with relatively large diameters, which leads to assembly difficulties and the risk of damaging at least one of the two wafers. Due to the very different thermal expansion coefficients of the materials used, it is difficult to use standard microelectronics manufacturing processes for bonding the substrates together; since the latter requires temperatures above 250°C, the mechanical stresses generated by the rise in temperature potentially lead to breakage of the wafers.

[0006] An objective of the present invention is to overcome at least one of the drawbacks of the prior art, preferably while retaining the advantages it presents. RESUME

[0007] To achieve this objective, according to a first aspect of the invention, there is provided a phase shift unit cell array for a transmitting array antenna, comprising: a first substrate based on one or other of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz, and comprising vias through the first substrate, at least two tiles, for example resulting from a cut in a second substrate based on one or other of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz, and each comprising at least one via through the tile, three metallization levels including a first metallization level located under the first substrate, a second metallization level located on each tile and a third metallization level located between each tile and the first substrate, each tile being fixed on the first substrate to form a phase shift unit cell of the phase shift unit cell array, at least one via through each tile being associated with one of the vias through the first substrate by being located in line with each other, and the vias associated with each other interconnecting the three metallization levels with each other and each tile being able to have a different thickness.

[0008] According to a second aspect, there is provided a transmitting array antenna comprising an array of phase shifting unit cells as introduced above and a primary source electromagnetically connected to said array of phase shifting unit cells.

[0009] According to a third aspect, there is provided a method of manufacturing a phase shift unit cell array for a transmitting array antenna, comprising: providing a first substrate based on one of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz, and comprising vias through the first substrate, providing a second substrate based on one of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz, and comprising vias through the second substrate, providing a first metallization level located under the first substrate and a first half of a third metallization level located on the first substrate, providing a second metallization level located on the second substrate and a second half of the third metallization level located under the second substrate, and then cutting at least one first tile in the second substrate, said at least one first tile comprising at least one of the vias of the second substrate,transferring said at least one first pad onto the first substrate, such that at least one via through each first pad is associated with one of the vias through the first substrate, being located in line with each other, and such that the vias associated with each other interconnect the three metallization levels with each other.

[0010] The invention according to each of its different aspects can thus consist of, or result in, a first substrate on which is fixed in pieces, or equivalently in blocks, a second substrate from which the pieces or blocks have been cut. This relaxes the flatness constraints of the assembly surfaces and / or reduces the risk of breakage of the substrates during their handling and / or their manufacture when they are subjected to thermomechanical constraints. BREVE DESCRIPTION DES FIGURES

[0011] The aims, objects, as well as the characteristics and advantages of the invention will emerge more clearly from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which: There figure 1 schematically represents a sectional side view of a transmitting array antenna according to an embodiment of the second aspect of the invention. The figure 2 schematically represents a perspective view of a transmitting array antenna according to an embodiment of the second aspect of the invention. The figure 3 schematically represents a sectional view of a portion of a phase shifting unit cell array according to an embodiment of the first aspect of the invention. The figure 4A represents a perspective and transparent view of an array of phase shift cells according to an embodiment of the first aspect of the invention. figure 4B schematically represents a profile and transparent view of the phase shift cell network illustrated in the figure 4A . THE figures 5 has 9 schematically represent steps of an embodiment of the method of manufacturing the part of the phase shift unit cell array which is illustrated in the figure 3 . There figure 10 schematically represents a sectional view of a part of an array of phase shifting unit cells according to another embodiment of the first aspect of the invention relative to that illustrated in the figure 3 . There figure 11 schematically represents a sectional view of a part of an array of phase shifting unit cells according to another embodiment of the first aspect of the invention relative to that illustrated in the figure 3 and the one illustrated on the figure 10 .

[0012] The drawings are given as examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily to the scale of practical applications. In particular, the relative thicknesses of the different layers illustrated in the drawings are not representative of reality. DESCRIPTION DÉTAILLÉE

[0013] Before beginning a detailed review of embodiments of the invention, optional characteristics which may possibly be used in combination or alternatively are set out below: According to an example of the first aspect of the invention, the first substrate has a characteristic transverse dimension greater than or equal to 100 mm, or even greater than or equal to 200 mm, and / or said at least one block has a characteristic transverse dimension greater than or equal to 200 µm and strictly less than 50 mm, preferably less than 5 mm.

[0014] According to an example of the first aspect of the invention, each tile is attached to the first substrate to form a single phase shifting unit cell of the phase shifting unit cell array.

[0015] According to an example of the first aspect of the invention, the vias associated with each other are in electrical conduction with each other.

[0016] According to an example of the first aspect of the invention, the vias are made from a good electrically conductive material, such as copper, or are made from at least one stack of good electrically conductive materials, such as copper, gold and nickel.

[0017] According to an example of the first aspect of the invention, at least four, preferably at least sixteen, tiles are attached to the first substrate so as to give the array of phase shifting unit cells the shape of a two-dimensional matrix of phase shifting unit cells.

[0018] According to an example of the first aspect of the invention, for at least one, preferably for each, phase shift unit cell, the third metallization level interconnects at least one pair of metal layers including a first metal layer extending from one of the vias through the pad of the phase shift unit cell in question and a second metal layer extending from one of the vias through the first substrate which is associated with the pad of the phase shift unit cell in question.

[0019] According to an example of the first aspect of the invention, the third metallization level interconnects at least two metal layers extending under two adjacent tiles with a metal layer extending on the first substrate. According to this example, it is possible to interconnect, for example in series, two adjacent tiles by interconnecting certain metal layers of said adjacent tiles via a metal layer extending on the first substrate.

[0020] According to an example of the first aspect of the invention, for at least one, preferably for each, phase shift unit cell, at least one, preferably each, metal layer extending under the pad of the cell in question is connected to one of the metal layers extending on the first substrate by means of at least one metal pillar, for example based on copper (and / or silver and / or tin).

[0021] According to the previous example, the third metallization level further comprises an underfill material arranged so as to consolidate the fixing of each paving stone to the first substrate, where appropriate the underfill material filling interstices between metal layers and / or interstices between metal pillars.

[0022] According to an example of the first aspect of the invention, alternative or complementary to the two previous ones, for at least one, preferably for each, phase shift unit cell, the third metallization level comprises a pair of two damascene levels, one extending on the first substrate and the other extending under the tile of the phase shift unit cell considered, the two damascene levels of each pair corresponding to each other, so that the fixing of the tile of the phase shift unit cell considered is carried out by direct bonding, silicon oxide being intercalated between the metal layers which are connected to each other.

[0023] According to an example of the first aspect of the invention, at least one, preferably each, phase shifting unit cell further comprises at least one phase change material switch formed at the third metallization level.

[0024] According to the preceding example, at least one, preferably each, phase change material switch extends under at least one pad. According to this example, it is possible to test the switch before transferring the pad with which it is associated onto the first substrate, so as to only transfer pads associated with functional switches, and thus increase manufacturing yield.

[0025] According to an example of the first aspect of the invention, the phase shifting unit cell array is silicon-free.

[0026] According to an example of the first aspect of the invention, said at least one block and the first substrate are made from the same material chosen from fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz. This avoids having materials with different thermal expansion coefficients.

[0027] According to an example of the third aspect of the invention, each of the first substrate and the second substrate has a characteristic transverse dimension greater than or equal to 100 mm, or even greater than or equal to 200 mm, and / or said at least one block has a characteristic transverse dimension greater than or equal to 200 µm and strictly less than 50 mm, preferably less than 5 mm.

[0028] According to an example of the third aspect of the invention, the first substrate and the second substrate are based on the same material.

[0029] According to an example of the third aspect of the invention, the cutting is carried out around a unit cell.

[0030] According to an example of the third aspect of the invention, at least four, preferably at least sixteen, tiles are cut and then transferred, so that the tiles form, with the parts of the first substrate on which they are transferred, an array of phase shift unit cells taking the form of a matrix of phase shift unit cells.

[0031] According to an example of the third aspect of the invention, the method further comprises: providing at least one third substrate based on one or other of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz, and comprising vias through the third substrate, and providing a second metallization level located on the third substrate and a second half of the third metallization level located under the third substrate, then, cutting at least one second tile in the third substrate, around a phase shift unit cell of the third substrate, transferring said at least one second tile onto the first substrate, such that at least one via through each second pad is associated with one of the vias through the first substrate, being located at right angles to each other, and such that the vias associated with each other interconnect the three metallization levels with each other. Thus, the pads may come from different substrates, and these may for example have different thicknesses with each other, such that the pads cut therein may be transferred to the same first substrate for a network of phase shift unit cells whose phase shift cells have different thicknesses with each other.

[0032] According to an example of the third aspect of the invention, the cutting of at least one, preferably each, paving stone comprises a cutting, for example by laser or by saw, in the thickness of the substrate concerned.

[0033] According to an example of the third aspect of the invention, for at least one, preferably for each, phase shift unit cell, the transfer of the first tile onto the first substrate is carried out by means of the metal pillars, and further comprises the filling with an underfilling material of the interstices between metal layers which constitute the three metallization levels and / or between interstices between metal pillars.

[0034] According to an example of the third aspect of the invention, alternative or complementary to the previous one, for at least one, preferably for each, phase shift unit cell, the transfer of the first tile onto the first substrate is carried out by direct bonding, the third metallization level comprising a pair of two damascene levels, one extending over the first substrate and the other extending under the tile of the phase shift unit cell considered.

[0035] A film or layer based on a material A means a film or layer comprising this material A and possibly other materials.

[0036] A parameter that is "substantially equal to / greater than / less than" a given value means that this parameter is equal to / greater than / less than the given value, within plus or minus 20% or even 10% of this value. A parameter that is "substantially between" two given values means that this parameter is at least equal to the smallest given value, within plus or minus 20% or even 10% of this value, and at most equal to the largest given value, within plus or minus 20% or even 10% of this value.

[0037] It is specified that, in the context of the present invention, the terms "on", "under", "overcomes", "covers", "underlying" and their equivalents do not necessarily mean "in contact with". Thus, for example, the transfer, application or deposition of a first layer on a second layer does not necessarily mean that the two layers are in direct contact with each other, but means that the first layer at least partially covers the second layer by being either directly in contact with it, or by being separated from it by at least one other layer or at least one other element.

[0038] In the following description, substrate, film or layer thicknesses are generally measured in directions perpendicular to the main plane of extension of the substrate, film or layer.

[0039] Generally speaking, phase change materials are 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 the crystalline phase.

[0040] In the following description, substrate, film or layer thicknesses are generally measured in directions perpendicular to the main plane of extension of the substrate, film or layer.

[0041] A first embodiment of the phase shift unit cell array 1 according to the first aspect of the invention is described below with reference to the figure 3 .

[0042] The phase shift unit cell array 1 for transmitting antenna 0, as shown in the figure 3 , but also as illustrated on the figures 10 And 11 , understand : a first substrate 11 based on either fused silica or quartz and comprising a matrix of vias 111 through the first substrate 11, at least one pad 12, preferably resulting from a cut in a second substrate 21 based on either fused silica and quartz, comprising at least one via 121 through the pad 12, and three metallization levels 13, 14, 15 including a first metallization level 13 located under the first substrate 11, a second metallization level 14 located on each pad 12 and a third metallization level 15 located between each pad 12 and the first substrate 11.

[0043] Each pad 12 is fixed on the first substrate 11 to form a phase shift unit cell 10 of the phase shift unit cell array 1, each via 121 through each pad 12 possibly being associated with one of the vias 111 through the first substrate 11 by being located in line with each other, and the vias 111 and 121 associated with each other interconnecting the three metallization levels 13, 14, 15 with each other.

[0044] As illustrated in the figure 11 , each phase shift unit cell 10 may comprise at least one phase change material switch 101 formed at the third metallization level 15.

[0045] Vias 111 and 121 may be made from a good electrically conductive material, such as copper. Alternatively, they may be made from at least one stack of good electrically conductive materials, such as copper, tin, silver, or gold, for example as described in Kim's scientific article. et al. which is referenced in the introduction.

[0046] More particularly, and as illustrated on the figures 3 , 10 And 11, for at least one, preferably for each, phase shift unit cell 10, the third metallization level 15 can make it possible to interconnect at least one pair of metal layers 152 including a first metal layer 1521 extending from the via 121 through the pad 12 of the phase shift cell 10 considered and a second metal layer 1522 extending from the via 111 through the first substrate 11 which is associated with the pad 12 of the phase shift cell 10 considered.

[0047] As an alternative or in addition, and always as illustrated on the figures 3 , 10 And 11, the third metallization level 15 can make it possible to interconnect with each other at least two metal layers 1523 extending under two adjacent blocks 12 with a metal layer 1524 extending on the first substrate 11. It is thus possible to interconnect with each other, for example in series, two adjacent blocks 12 by interconnecting certain metal layers 1523 of said adjacent blocks 12 with each other via a metal layer 1524 extending on the first substrate 11.

[0048] The schematic representation offered by the figure 3 is only partial. The entire phase shift unit cell network 1 is illustrated on the figures 4A et 4B which show an organization in matrix form of 4*4 unit cells of phase shift 10. The nature, for example square, of the two-dimensional matrix, as well as the number of phase shift cells 10 that it can comprise, are however not limited to the example illustrated on the figures 4A et 4B .

[0049] An embodiment of the manufacturing method according to the 2nd aspect of the invention is illustrated in the figures 5 has 9 which results in the embodiment of the phase shift unit cell array 1 which is illustrated in the figure 3 .

[0050] The manufacturing process according to the implementation method illustrated on the figures 5 has 9 is essentially such that it comprises: providing a first substrate 11 based on either fused silica or quartz and comprising an array of vias 111 through the first substrate 11 (Cf. figure 5 ), providing a second substrate 20 based on either fused silica and quartz and comprising an array of vias 121 through the second substrate 20 (Cf. figure 5 ), provide a first metallization level 13 located under the first substrate 11 and a first half 1501 of a third metallization level 15 located on the first substrate 11 (Cf. figure 5 ), provide a second metallization level 14 located on the second substrate 20 and a second half 1502 of the third metallization level 15 located under the second substrate 20 (Cf. figure 5 ), then cut at least a first block 12 in the second substrate 20, around one of the vias 121 or more generally around a phase shift unit cell of the second substrate 20 (Cf. figures 7 And 8 ), transfer said at least one first block 12 onto the first substrate 11 (Cf. figure 9 ).

[0051] In this way, the via(s) 121 through each first pad 12 are possibly associated with one or more vias 111 through the first substrate 11, being located in line with each other, and the vias 111 and 121 associated with each other interconnect the three metallization levels 13, 14, 15 with each other.

[0052] More particularly, the steps of providing the first substrate 11 and the second substrate 20 may be as described in the scientific article by R. Bowrothu et al., referenced in the introduction.

[0053] Note that the cutting is preferably carried out around a single phase shift unit cell of the second substrate 20. Alternatively, it is possible to transfer a plurality of blocks 12, for example forming a 2*2 or 4*4 matrix, or more, and not necessarily square, by cutting the second substrate 20 around this plurality. Each cutting is for example carried out using a laser or a saw. It preferably takes effect in the thickness of the second substrate 20, the laser being for example kept perpendicular to a main extension surface of the second substrate 20 during each cutting.

[0054] In reference to the figure 6 , the manufacturing method according to the illustrated embodiment may more particularly be such that, for at least one, preferably for each, phase shift unit cell 10, the transfer of the first block 12 onto the first substrate 11 is carried out by means of the metal pillars 151. The manufacturing method may then further comprise, from the illustration offered by the figure 9 , filling with an underfilling material the interstices between metallic layers 1521, 1522, 1523, 1524 which constitute the three metallization levels 13, 14, 15 and / or between interstices between metallic pillars 151, in the manner illustrated in the figure 3 .

[0055] So, as illustrated on the figure 3 , for at least one, preferably for each, phase shift unit cell 10, at least one, preferably each, metal layer 1521, 1523 extending under the pad 12 of the cell 10 considered can be connected to one of the metal layers 1522, 1524 extending on the first substrate 11 by means of at least one metal pillar 151, for example based on copper.

[0056] Furthermore, as always illustrated on the figure 3 , the third metallization level 15 may comprise an underfill material 153 arranged so as to consolidate the fixing of each block 12 to the first substrate 11, where appropriate the underfill material 153 filling interstices between the metal layers 1521, 1522, 1523, 1524 and / or interstices between metal pillars 151.

[0057] As an alternative to the embodiment illustrated in the figure 3 , the embodiment illustrated on the figure 10 is such that, for at least one, preferably for each, phase shift unit cell 10, the third metallization level 15 comprises a pair of two damascene levels. A first damascene level 1526 then extends over the first substrate 11 and a second damascene level 1527 then extends under the pad 12 of the phase shift unit cell 10 in question. Preferably, the two damascene levels 1526, 1527 of each pair correspond to each other. In this way, the fixing of the pad 12 of the phase shift unit cell 10 in question is carried out by direct bonding. Silicon oxide 1528 is then, if necessary, intercalated between the interstices of the metal layers 1521, 1522, 1523, 1524 which are connected to each other.

[0058] Preferably, at least one, or even each, block 12 and the first substrate 11 are made from the same material chosen from fused silica and quartz. This avoids having materials with different thermal expansion coefficients, which reduces the risks of breaks in the network, in particular during steps of integrating said network into a transmission antenna 0.

[0059] Such an antenna in transmission 0 is illustrated in the figures 1 et 2 . It comprises, in addition to the network of phase-shifting unit cells 1 according to the first aspect of the invention, at least one primary source 2 electromagnetically connected to said network of phase-shifting unit cells 1.

[0060] In a manner not illustrated in the figures, the person skilled in the art will understand that it is possible that certain blocks 12 to be transferred onto the first substrate 11 do not come from the second substrate 20, but from a third substrate having, for example, a thickness different from that of the second substrate 20, and more particularly a layer based on one of fused silica and quartz having a thickness different from that of the second substrate 20. Thus, the blocks 12 may come from different substrates, and the latter may, for example, have different thicknesses from one another, so that the blocks 12 which are cut therein may be transferred onto the same first substrate 11 for an array of phase-shifting unit cells 1 whose phase-shifting unit cells 10 have different thicknesses from one another.

[0061] The invention according to each of its different aspects can thus consist of, or result in, a first substrate 11 on which is fixed in pieces, or equivalently in blocks 12, a second substrate 20 from which the pieces or blocks 12 have been cut. This advantageously avoids having to transfer one substrate onto another substrate, thus relaxing the flatness constraints of the assembly surfaces and / or reducing the risk of breakage of the substrates during their handling and / or their manufacture when they are subjected to thermomechanical constraints.

[0062] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

Claims

1. Phase shift unit cell array (1) for a transmitting array antenna, comprising: • a first substrate (11) based on one or other of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz and comprising vias (111) through the first substrate (11), • at least two blocks (12) resulting from a cut in a second substrate (21) based on one or other of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz and each comprising at least one via (121) through the block (12), • three metallization levels (13, 14, 15) including a first metallization level (13) located under the first substrate (11), a second metallization level (14) located on each pad (12) and a third metallization level (15) located between each pad (12) and the first substrate (11),each pad (12) being fixed on the first substrate (11) to form a phase shift unit cell (10) of the phase shift unit cell array (1), at least one via (121) through each pad (12) being associated with one of the vias (111) through the first substrate (11) by being located in line with each other, and the vias (111 and 121) associated with each other interconnecting the three metallization levels (13, 14, 15) with each other and each pad being able to have a different thickness., 2. Phase shift unit cell array (1) according to the preceding claim, wherein at least four, preferably at least sixteen, tiles (12) are fixed on the first substrate (11) so as to give the phase shift unit cell array (1) the shape of a two-dimensional matrix of phase shift unit cells (10).

3. A phase shift unit cell array (1) according to any preceding claim, wherein, for at least one, preferably for each, phase shift unit cell (10), the third metallization level (15) interconnects at least one pair of metal layers (152) including a first metal layer (1521) extending from one of the vias (121) through the pad (12) of the phase shift unit cell (10) in question and a second metal layer (1522) extending from one of the vias (111) through the first substrate (11) which is associated with the pad (12) of the phase shift unit cell (10) in question.

4. Phase shift cell array (1) according to any one of the preceding claims, wherein the third metallization level (15) interconnects between them at least two metal layers (1523) extending under two adjacent tiles (12) with a metal layer (1524) extending on the first substrate (11).

5. Phase shift unit cell array (1) according to either of the two preceding claims, wherein, for at least one, preferably for each, phase shift unit cell (10), at least one, preferably each, metal layer (1521, 1523) extending under the pad (12) of the cell (10) in question is connected to one of the metal layers (1522, 1524) extending on the first substrate (11) via at least one metal pillar (151), for example copper-based.

6. Phase shift unit cell array (1) according to the preceding claim, wherein the third metallization level (15) further comprises an underfill material (153) arranged so as to consolidate the fixing of each tile (12) to the first substrate (11), where appropriate the underfill material (153) filling interstices between metal layers (1521, 1522, 1523, 1524) and / or interstices between metal pillars (151).

7. Phase shift unit cell array (1) according to any one of the four preceding claims, wherein, for at least one, preferably for each, phase shift unit cell (10), the third metallization level (15) comprises a pair of two damascene levels, one (1526) extending on the first substrate (11) and the other (1527) extending under the tile (12) of the phase shift unit cell (10) in question, the two damascene levels (1526, 1527) of each pair corresponding to each other, so that the fixing of the tile (12) of the phase shift unit cell (10) in question is carried out by direct bonding, silicon oxide (1528) being interposed between the metal layers (1521, 1522, 1523, 1524) which are connected to each other.

8. A phase shift unit cell array (1) according to any preceding claim, wherein at least one, preferably each, phase shift unit cell further comprises at least one phase change material switch (101) formed at the third metallization level (15).

9. Phase shift unit cell array (1) according to any one of the preceding claims, wherein said at least one tile (12) and the first substrate (11) are made from the same material chosen from fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz.

10. A transmitting array antenna (0) comprising a phase shift unit cell array (1) according to any preceding claim and a primary source (2) electromagnetically connected to said phase shift unit cell array (1).

11. A method of manufacturing a phase shift unit cell array (1) for a transmitting array antenna (0), comprising: • providing a first substrate (11) based on one of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz, and comprising vias (111) through the first substrate (11), • providing a second substrate (20) based on one of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz, and comprising vias (121) through the second substrate (20), • providing a first metallization level (13) located under the first substrate (11) and a first half (1501) of a third metallization level (15) located on the first substrate (11),• providing a second metallization level (14) located on the second substrate (20) and a second half (1502) of the third metallization level (15) located under the second substrate (20), then • cutting at least one first pad (12) in the second substrate (20), said at least one first pad (12) comprising at least one of the vias (121) of the second substrate (20), • transferring said at least one first pad (12) onto the first substrate (11), so that at least one via (121) through each first pad (12) is associated with one of the vias (111) through the first substrate (11), being located in line with each other, and so that the vias (111 and 121) associated with each other interconnect the three metallization levels (13, 14, 15) with each other., 12. Manufacturing method according to the preceding claim, in which at least four, preferably at least sixteen, blocks (12) are cut out and then transferred, so that the blocks (12) form, with the parts of the first substrate (11) on which they are transferred, a network of phase shift unit cells (1) taking the form of a matrix of phase shift unit cells (10).

13. Manufacturing method according to either of the two preceding claims, comprising: • providing at least one third substrate based on one or other of fused silica, quartz and a glass having a loss tangent of less than 0.005 at frequencies above 100 GHz, and comprising vias through the third substrate, and • providing a second metallization level located on the third substrate and a second half of the third metallization level located under the third substrate, then, • cutting at least one second tile in the third substrate, around a phase shift unit cell of the third substrate, • transferring said at least one second tile onto the first substrate, such that at least one via through each second tile is associated with one of the vias through the first substrate, being located in line with each other,and so that the vias associated with each other interconnect the three metallization levels between them., 14. Method according to any one of the three preceding claims, in which, for at least one, preferably for each, phase shift unit cell (10), the transfer of the first tile (12) onto the first substrate (11) is carried out by means of the metal pillars (151), and further comprises the filling with an underfilling material of the interstices between metal layers (1521, 1522, 1523, 1524) which constitute the three metallization levels (13, 14, 15) and / or between interstices between metal pillars (151).

15. Method according to any one of the four preceding claims, in which, for at least one, preferably for each, phase shift unit cell (10), the transfer of the first tile (12) onto the first substrate (11) is carried out by direct bonding, the third metallization level (15) comprising a pair of two damascene levels, one (1526) extending over the first substrate (11) and the other (1527) extending under the tile (12) of the phase shift unit cell (10) in question.

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