Antenna arrangement employing radiation shielding for integrated circuits

Abstract

The antenna device includes a radiation shield between an antenna element and at least one radio frequency integrated circuit (RFIC) coupled to the antenna element. The antenna substrate includes a first dielectric layer having opposing first and second surfaces, and a first metallization layer attached to the second surface to form a ground plane. The base substrate includes at least a second dielectric layer having opposing third and fourth surfaces, and a second metallization layer having a first side attached to the third surface and a second side attached to the first metallization layer to form a radiation shield. The RFIC is RF coupled to the antenna element through at least one via extending through the base substrate and coupling elements in aligned openings in the first and second metallization layers.

Description

[Technical field]

[0001] The present disclosure relates generally to antennas, and more particularly to an antenna arrangement with a radiation shield for radio frequency (RF) circuitry integrated with the antenna element. [Background technology]

[0002] In space, military, and some industrial environments, antenna elements and associated RF circuits may be exposed to radiation, such as ionizing radiation, solar radiation, cosmic background radiation, wave radiation, particle radiation, and / or electromagnetic radiation. Without proper shielding, RF circuits may be particularly vulnerable to radiation. For example, a thin, generally planar structure for an antenna device may have a sandwich-type configuration with antenna elements disposed in an outwardly facing component layer, and integrated circuits (ICs) distributed across parallel component layers behind the antenna element layer. The ICs may include an RFIC with front-end circuits such as an RF power amplifier (PA) for transmit operation, a low noise amplifier (LNA) for receive operation, and a phase shifter for beam steering. For optimal performance, it is desirable for the RFIC to be close to the antenna element. Other ICs may include circuits that provide bias and control signals to the RFIC, or baseband / digital signal processing circuits.

[0003] The antenna element may be a microstrip patch element printed on an antenna substrate with an antenna ground plane printed on the opposite side. The antenna ground plane may provide some radiation resistance to the IC. However, certain types of high intensity radiation may still penetrate the ground plane and degrade the IC, resulting in a reduced reliability of the antenna system. Summary of the Invention

[0004] In one aspect of the invention, an antenna device includes an antenna substrate and a base substrate. The antenna substrate includes a first dielectric layer having opposing first and second surfaces, and a first metallization layer adjacent to the second surface to form a ground plane. At least one antenna element is attached to the first surface. The base substrate includes at least a second dielectric layer having opposing third and fourth surfaces, and a second metallization layer having a first side adjacent to the third surface and an opposing second side attached to the first metallization layer to form a radiation shield. The first and second metallization layers are aligned with each other, respectively, and have first and second openings underlying the antenna element. At least one RFIC is disposed adjacent to the fourth surface of the base substrate and RF-coupled to the at least one antenna element via at least one via extending through the base substrate and coupling elements in the first and second openings.

[0005] In one embodiment, the first and second metallization layers are attached and electrically connected through a conductive adhesive therebetween, In an alternative embodiment, the first and second metallization layers are attached by a fill material layer having a thickness greater than the thickness of each of the first and second metallization layers.

[0006] In another aspect, a method of manufacturing an antenna device includes forming an antenna substrate including a first dielectric layer having opposing first and second surfaces and a first metallization layer adjacent to the second surface forming a ground plane for at least one antenna element. A first opening is formed in the first metallization layer. At least one antenna element is attached to the first surface of the antenna substrate. A base substrate is formed including at least a second dielectric layer having opposing third and fourth surfaces, at least one via extending through the second dielectric layer, and a second metallization layer adjacent to the third surface to form at least a portion of a radiation shield in conjunction with the first metallization layer. The second metallization layer has a second opening aligned with the first opening. At least one signal via is formed extending through the second dielectric layer having a first end in the second opening. The antenna substrate is attached to the base substrate by at least connecting coupling elements in the first and second openings between the signal via and the antenna substrate. A first metallization layer is attached to the second metallization layer, and at least one RFIC is attached to the fourth surface of the base substrate and electrically connected to the at least one signal via. [Brief description of the drawings]

[0007] The above and other aspects and features of the disclosed technology will become more apparent from the following detailed description in conjunction with the accompanying drawings in which like reference characters indicate like elements or features. Various elements of the same or similar type may be distinguished by adding a reference label with an underline / dash and a second label that distinguishes among the same / similar elements (e.g., _1, _2), or by directly adding the reference label with the second label. However, if a given description uses only a first reference label, this label is applicable to any of the same / similar elements having the same first reference label, regardless of the second label. Elements and features may not be drawn to scale in the drawings.

[0008] [Figure 1] FIG. 1 is a cross-sectional view of an antenna device according to one embodiment showing a first example of an interlayer structure for radiation shielding of an IC of the antenna device. [Diagram 2] FIG. 2 is a cross-sectional view of the antenna apparatus of FIG. 1 taken along line 2-2. [Diagram 3] FIG. 3 is a cross-sectional view of an antenna device having a multi-layer base substrate according to an embodiment. [Figure 4] FIG. 4 is a cross-sectional view of an antenna arrangement including a filler that forms part of a radiation shield, according to one embodiment. [Diagram 5] FIG. 5 is a cross-sectional view of the antenna arrangement of FIG. 4 taken along line 5-5. [Figure 6] FIG. 6 is a cross-sectional view of an alternative coaxial structure incorporating a coupling element within the antenna apparatus of FIG. [Figure 7] FIG. 7 is a cross-sectional view of another alternative coaxial structure incorporating a coupling element within the antenna apparatus of FIG. [Figure 8] FIG. 8 is a perspective view of a further alternative coaxial structure incorporating a coupling element within the antenna arrangement of FIG. [Figure 9] FIG. 9 is a cross-sectional view of an antenna arrangement including a filler and additional shielding structure forming part of a radiation shield according to one embodiment. [Figure 10] FIG. 10 is a plan view showing an example of the layout of a phased array antenna apparatus according to an embodiment. [Figure 11] FIG. 11 is a flow diagram illustrating an exemplary method for manufacturing an antenna device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] For the purpose of explanation, the following description is provided with reference to the accompanying drawings to assist in a comprehensive understanding of certain exemplary embodiments of the technology disclosed herein. Although the description includes various specific details to assist those skilled in the art in understanding the technology, these details should be considered as merely exemplary. For the purpose of simplicity and clarity, descriptions of well-known functions and structures may be omitted if their inclusion may obscure the understanding of the technology by those skilled in the art.

[0010] FIG. 1 is a cross-sectional view of an antenna device 100 according to one embodiment. The antenna device 100 may include an antenna substrate 40, a base substrate 50, an antenna element 20, and an RFIC chip or wafer 30 (hereinafter simply "RFIC 30"), e.g., a monolithic microwave integrated circuit (MMIC). Although one antenna element 20 and one RFIC 30 are illustrated, in various embodiments, the antenna device 100 is configured as an active antenna array, e.g., a phased array, in which multiple antenna elements 20 are arranged across a top surface of the antenna substrate 40 (the xy plane in FIG. 1) and multiple RFICs 30 are arranged across a bottom surface of the base substrate 50. (In this specification, for ease of explanation and understanding, "top" and "bottom" are used as relative terms. The top surface of the antenna substrate 40 is an outer surface that interfaces with free space.) Each RFIC 30 is RF coupled to at least one antenna element 20 through a coupling structure in the base substrate 50 and the antenna substrate 40. In a typical embodiment, the antenna arrangement 100 has a thin, plate-like profile with a maximum thickness (in the Z direction) that is at least an order of magnitude smaller than the maximum orthogonal direction (in the xy plane).

[0011] The antenna substrate 40 may include a first dielectric layer 42 to which the antenna element 20 is attached and a first metallization layer 44 adjacent a bottom surface of the dielectric layer 42. The first metallization layer 44 forms a ground plane for the antenna element 20 and may hereafter also be referred to as the "ground plane 44." The base substrate 50 may include a second dielectric layer 52 with top and bottom surfaces, and a second metallization layer 54 adjacent the top surface. The RFIC 30 is adjacent a bottom surface of the second dielectric layer 52. In some examples, the dielectric layers 42 and 52 are comprised of glass (e.g., fused silica) or quartz.

[0012] The first metallization layer 44 may be attached to the second metallization layer 54 by a conductive adhesive 60. Collectively, the first metallization layer 44, the adhesive 60, and the second metallization layer 54 form a radiation shield 64 that protects the RFIC 30 from radiation R that penetrates the top surface of the first dielectric layer 42. Such radiation R may be in the form of ionizing radiation, wave radiation, particle radiation, solar radiation, cosmic background radiation, and / or electromagnetic radiation. The thickness and composition of the first and second metallization layers 44 and 54 are designed to reduce the level of harmful radiation that penetrates the second dielectric layer 52 toward the RFIC 30.

[0013] In one example, the metallization layers 44 and 54 are each formed by a metal pillar (or metal "bump") formation process, such as a copper pillar, gold pillar, or platinum pillar formation process. The adhesive 60 may be a solder cap layer and will typically be thinner than each of the metallization layers 44 and 54. In one embodiment, the metallization layers 44 and 54 are each at least 50 μm thick (thickness is in the z-direction in FIG. 1). In another embodiment, the layers 44 and 54 are each at least 100 μm thick. For example, in space applications, it is desirable to protect against total ionizing dose (TID) caused by radiation induced charge generation / capture. When the metallization layers 44 and 54 are each constructed from a thick, dense material, such as a pure metal, such as copper, tantalum, platinum, or a metal alloy, sufficient shielding can be provided to protect against this type of radiation. One way to design an appropriate thickness for a given material is to consider the required lifetime of the antenna device 100 in the operating environment. When installed on board a satellite in orbit, radiation dose depth curves may be referenced that correlate the thickness of a given material required to attenuate annual radiation levels to a certain amount. Specifications for the expected or minimum lifetime of RFIC 30 in a given radiation environment may also be considered. With such information, the thicknesses of metallization layers 44 and 54, as well as the thickness and composition of dielectric layer 52 of base layer 50 may be designed.

[0014] As an example, for a conventional antenna arrangement that does not utilize attached metallization layers 44 and 54, the MMIC behind the antenna substrate 40 (e.g., attached directly to the underside of the antenna substrate 40) may receive approximately 500 krad of radiation per year. For an antenna arrangement 100 incorporating a radiation shield 64 having a thickness that includes 100 μm of copper, and a dielectric layer 522 constructed of fused silica, the RFIC 30 may receive approximately 150 krad of radiation per year. If the thickness of the radiation shield 64 is increased to include 200 μm of copper, the RFIC 30 may receive approximately 75 krad of radiation per year. Thus, in these examples, the total incident radiation over time is significantly reduced, thereby increasing the life of the RFIC 30. In another example, if the copper in the metallization layers 44 and 54 is replaced with a denser material such as tantalum or platinum of the same thickness, the radiation incident on the RFIC 30 is reduced even further. It should also be noted that fused silica is an example of a material that also provides significant shielding against radiation. Thus, the dielectric layer 52 of the base substrate 50 provides a portion of the radiation shield when constructed from fused silica or a similar material. For example, 250 μm of fused silica has a density equivalent to about 60 μm of copper and may provide approximately the same attenuation in radiation.

[0015] In general, the thickness of metallization layers 44 and 54 may be at least an order of magnitude greater than the thickness of antenna element 20 (which is shown exaggerated in FIG. 1 relative to layers 44 and 54). In an exemplary embodiment, antenna element 20 may be a printed element formed by a thin film process. Antenna device 100 may also include a peripheral shield 104 (shown diagrammatically in FIG. 1) surrounding the entire structure to reduce radiation incident from peripheral directions. Peripheral shield 104 may be in the form of a continuous metal housing.

[0016] The first metallization layer 44 may have an opening 81a aligned with an opening 81b in the second metallization layer 54, with the openings 81a and 81b underlying the antenna element 20. A coupling element 85 may be formed centrally within the coaxial structure in the region of the openings 81a and 81b. The coupling element 85 may include an upper metal post 44a, a lower metal post 54a, and a conductive adhesive 60a that conductively attaches the metal posts 44a and 54a. The metal posts 44a and 54a are part of the metal post layers 44 and 54, respectively, and may be formed as part of the same process that formed the respective layers 44 and 54. The conductive adhesive 60a may be part of the adhesive 60.

[0017] The coupling element 85 may be understood as the inner conductor of a short coaxial transmission line ("coax") 80, which is described further below. The "signal via" 70 may extend vertically through the base substrate 52 and electrically connect at its bottom end to a "signal contact" 93s of the RFIC 30 through a conductive joint 91, such as a solder cap. The probe feed 47 may be a via formed through the first dielectric layer 42, with its bottom end connected to the top end of the metal post 44a and its top end connected to the antenna element 20. Thus, the RFIC 30 may be RF coupled to the antenna element 20 through the via 70, the coupling element 85, and the probe feed 47. In other embodiments, the probe feed 47 is omitted or only partially penetrates the dielectric layer 42 from the bottom surface of the dielectric layer 42. In this case, the coupling element 85 is electromagnetically (EM) coupled to the antenna element 20 (i.e., the antenna element 20 is EM excited through the via 70 and the coupling element 85).

[0018] It should be noted that instead of providing a coaxial line 80 formed in a metal post process at the opposite end and attaching the ends with conductive epoxy 60a, a preformed coaxial coupling structure in the form of an insertable coaxial line section may be substituted. This approach is described below in connection with Figure 8. The insertable section may have opposite ends suitably attached to the dielectric layers 42 and 52.

[0019] One or more ground contacts 93g of the RFIC 30 may be coupled (through adhesive 60) to the second metallization layer 54 and ground plane 44. Such coupling is made through one or more “ground vias” 72a and / or 72b that extend through the second dielectric layer 52 on one or more sides of the signal via 70. In embodiments in which more than one ground via 72a and 72b is included, a “ground-signal-ground (GSG)” transition or “GSG connection” between the RFIC 30 and the ground plane 44 includes the ground vias 72a and 72b and the signal via 70. In other embodiments in which only a single ground via is included, the connection between the RFIC 30 and the ground plane 44 may be described as a “ground-signal (GS) transition” or “GS connection,” which includes one ground via 72a or 72b and the signal via 70.

[0020] FIG. 2 is a cross-sectional view of the antenna device 100 taken along line 2-2 of FIG. 1. In FIG. 2, exemplary profiles of the antenna element 20, the RFIC chip 30, the first and second ground vias 72a and 72b are shown in phantom. With collective reference to FIGS. 1 and 2, an annular separation region 81 surrounds the coupling element 85 and extends to a peripheral edge 87 of the first and second metallization layers 44 and 54. The peripheral edge 87 defines openings 81a and 81b in the first and second metallization layers 44 and 54. The separation region 81 may be an air-filled region or may be filled with a dielectric material. The separation region 81 may be understood as the space surrounding the outer annular portions of the openings 81a and 81b (excluding the coupling element 85) and the vertical space (with the thickness of the adhesive 60) between them. The coupling element 85 together with the isolation region 81 and the peripheral edge 87 of the metallization layers 44 and 54 form the coaxial line 80, where the coupling element 85 is the inner conductor, the peripheral edge 87 is the outer conductor, and the isolation region 81 is a dielectric or air-filled spacer for the coaxial line 80. It should be noted, then, that although radiation R may penetrate the isolation region 81, the diameter of the region 81 is small compared to the dimensions of the antenna apparatus 100 in the xy plane, and therefore the penetrating radiation may have little effect on the RFIC 30 and other circuitry below the base substrate 50.

[0021] The above-mentioned GSG transition between the RFIC 30 and the ground plane 44 may be understood as a GSG transition between the RFIC 30 and the coaxial line 80. The isolation region 81 of the coaxial line 80 may be vertically aligned with the annular isolation region 73 between the signal via 70 and the ground vias 72a and 72b. Thus, RF signal energy may flow through the GSG transition, the coaxial coupling structure, and the RF feed surrounding the antenna feed (probe feed 47 or EM coupled antenna feed) in the dielectric substrate 42. In other words, the signal energy flows from the RFIC 30 through the isolation region 73 and isolation region 81 and the dielectric layer 42 to excite the antenna element 20. It is noted that additional ground vias (not shown) may be placed at other circumferential locations adjacent outside the edge 87 (as viewed from a distant point along the z-axis) to reduce signal leakage / noise.

[0022] The antenna element 20 may be a microstrip patch antenna element with a circular profile and may be offset fed by a probe feed 47 as shown in FIG. 2. In other examples, the antenna element 20 may have a rectangular, square, or other polygonal shape, or may have a rectangular or irregular shape, or may be a dipole or other type of antenna element. The patch antenna element may be formed by a thin film process and may have a thickness in the range of 1-5 μm. The RFIC 30 and its contacts 93 are preferably located directly under the antenna element 20 to provide a short overall connection between the RFIC 309 and the antenna element 20. The RFIC 30 includes at least one RF front-end circuit path 32 (hereinafter "RF circuit 32"). The RF circuit 32 includes at least one RF front-end circuit component such as an amplifier 33, a phase shifter 37, an active or passive filter, a transmit / receive (T / R) switch, an impedance matching circuit, an attenuator, an isolator, etc. The RFIC 30 may include other circuits such as a combiner / splitter, an upconverter, a downconverter, etc.

[0023] The type and configuration of antenna elements 20, their spacing from ground plane 44, and polarization may vary depending on the frequency band required for operation. Similar design considerations are applicable to the RFIC 30 and RF circuitry 32 circuitry. In an exemplary embodiment, the antenna apparatus 100 is configured for operation in the microwave or millimeter wave (mm) band, with microwave frequencies generally considered to be between 300 MHz and 30 GHz, and mm wave frequencies generally considered to be between 30 GHz and 300 GHz. However, the techniques herein may also be applied to antennas designed for sub-microwave frequencies, such as the UHF or VHF bands.

[0024] The antenna arrangement 100 may be configured as a transmitting antenna system, a receiving antenna system, or both a transmitting and receiving antenna system. In an active array embodiment, each RF circuit 32 includes an amplifier 33 and / or a phase shifter 37 for adjusting the transmit and / or receive signals provided to and / or from the antenna elements 20. Multiple RFICs 30 may be distributed behind the effective aperture of the antenna 100, each coupled to one or more antenna elements 20, in which case the antenna 100 may be understood as an active antenna array. In an embodiment in which the RF circuit 32 includes a phase shifter for dynamic phase shifting of the signals, the antenna 100 functions as a phased array. In such a phased array embodiment, the beam formed by the antenna 100 is steered to a desired beam pointing angle set primarily according to the phase shift of the phase shifter. Additional amplitude adjustment capability within the RFICs 30 may also be included to adjust the antenna pattern.

[0025] The RFIC chip 30 may receive bias voltages and control signals for controlling amplification, phase shifting, T / R switching, etc., by any suitable connection mechanism. For example, one or more control IC chips (not shown) may be attached to the bottom surface of the dielectric layer 52 and electrically connected to the RFIC 30 to provide bias / control signals. The bias / control signals may be routed through signal lines 59 formed by a patterned metallization layer in the bottom of the dielectric layer 52 (or formed in an additional thin dielectric layer on the bottom surface of the dielectric layer 52) and connected to the RFIC chip 30 through interconnects 58 (shown diagrammatically). These control IC chips may likewise be protected from incident radiation R by radiation shielding of the metallization layers 44 and 54. When multiple RFICs 30 are distributed across the bottom surface of the dielectric layer 52, they may each be coupled to a combiner / splitter network (not shown) for combining signals received by the antenna elements 20 to form receive beams and / or splitting signals transmitted through the antenna elements 20 to form transmit beams. The combiner / divider network may be located in a transmission line substrate(s) located between or beneath the RFICs 30, or may be formed by a patterned metal layer in the dielectric layer 52.

[0026] 3 is a cross-sectional view of an antenna device 200 having a multi-layer base substrate according to one embodiment. The antenna device 200 may have the same configuration and function as the antenna device 100 described above, but includes a base substrate 50' with multiple dielectric layers 52a and 52b and a patterned metallization layer 98 therebetween. The metallization layer 98 may be coupled to the RFIC 30 through one or more blind vias 95 and one or more contacts 93a of the RFIC 30. The metallization layer 98 may be patterned to form part of a combiner / splitter network for routing RF signals to / from the RFIC 30. The metallization layer 98 may alternatively or additionally be attached to a lower surface of the dielectric layer 52b and coupled to one or more control IC chips (not shown) that may provide bias / control signals.

[0027] FIG. 4 is a cross-sectional view of an antenna device 300 according to another embodiment. The antenna device 300 includes a filler layer 365 for improving manufacturing yield and structural integrity over a wide range of environmental conditions. FIG. 5 is a cross-sectional view of the antenna device 300 taken along line 5-5 of FIG. 4. With reference to FIG. 4 and FIG. 5, the antenna device 300 may include an antenna substrate 340, a base substrate 350, a filler layer 365, at least one antenna element 20, at least one RFIC chip 30 (or wafer) including an RFIC 32, and a coaxial coupling structure 380 (e.g., a short coaxial line) including a coupling element 85. To avoid redundancy, the description of elements with the same legend as above may be omitted.

[0028] The antenna substrate 340 may include a first dielectric layer 42 and a first metallization layer 367 adjacent to a lower surface of the dielectric layer 42, the first metallization layer 367 serving as a ground plane for the antenna element 20. The first metallization layer 367 may be thinner than the first metallization layer 44 of FIG. 1 and may be formed on the lower surface of the dielectric layer 42 by a thin film deposition process or the like. The base substrate 350 may include a second dielectric layer 52 and a second metallization layer 369. The second metallization layer 369 may be thinner than the second metallization layer 54 of FIG. 1 and may be formed on the upper surface of the dielectric layer 52 by a process similar to the first metallization layer 367. The filler layer 365 may be comprised of a compliant material that is inserted between the metallization layers 367 and 369 to completely fill the space around the coaxial coupling structure 380 after the coaxial coupling structure 380 is integrated with the antenna substrate 340 and the base substrate 350. Thus, the first and second metallization layers 367 and 369 may be attached to one another by the fill material layer 365 .

[0029] Collectively, the first and second metallization layers 367 and 369 and the filler material layer 365 form a radiation shield 364 to reduce the effect of incident radiation R on the RFIC 30 and any other circuitry below the base substrate 350. The filler material layer 365 may be a compliant material layer that reduces the likelihood of cracking of the dielectric layers 42 and / or 52 during manufacturing. The filler material layer 365 may thereby improve manufacturing yields for the antenna device 100. For example, without the filler material 365, the thick metal between the dielectric layers 42 and 52 may expand and contract at a higher rate than the dielectric layers 42 and 52 due to a mismatch in coefficient of thermal expansion (CTE) between the metal and the dielectric material. The CTE mismatch may result in cracking when the antenna device is exposed to high temperatures. In contrast, the filler material layer 365 may have a CTE close to the CTE of the dielectric layers 42 and 52, which may prevent such cracking. Some examples of the composition of the filler layer 365 include conductive epoxy, a mixture of tantalum and conductive epoxy, microwave absorbing materials, and underfill materials. The material of the filler layer 365 and its thickness may be selected based on the desired radiation attenuation, as described above in connection with the metallization layers 44 and 54. For example, a radiation dose depth curve may be referenced that correlates the thickness of the filler layer 365 material required to attenuate the annual radiation level to a certain amount. Due to its compatibility, the filler layer 365 may also prevent cracking in the area surrounding the coaxial coupling structure 380, even if a thick metal is used for the coupling element 85 and the surrounding outer conductor 382 (in the form of a hollow tube or ring) that connects the filler layer 365.

[0030] Vertically aligned openings 381a and 381b may be formed in first and second metallization layers 367 and 369, respectively. A coaxial bonding structure 380 having portions within and between openings 381a and 381b may include bonding element 85, an outer conductor 382, ​​and annular isolation region 381. As previously described, bonding element 85 may include upper metal post 44a, lower metal post 54a, and conductive adhesive 60a that conductively attaches metal posts 44a and 54a.

[0031] The outer conductor 382 may be of the same thickness (z-direction) as the coupling element 85 and formed simultaneously with the coupling element 85 using the same processing operations. Thus, the outer conductor 382 may include an upper ring portion 44b formed by a metal pillar build-up process on the surface of the dielectric layer 42 opposite the antenna element 20, a lower ring portion 54b formed by a metal pillar build-up process on the top surface of the dielectric layer 52, and a conductive adhesive layer 60b attaching the upper and lower ring portions 44b and 54b. With this structure, the coaxial coupling structure 380 may be formed as a short coaxial line section with the coupling element 85 as the inner conductor, the outer conductor 382, ​​and a separation region 381 separating the inner and outer conductors. The separation region 381 may include a portion of the openings 381a and 381b, as well as a volume region 381c therebetween. The separation region 381 may be filled with a low-loss dielectric material and may be vertically aligned with the annular separation region 73 between the signal via 70 and the ground vias 72a and 72b. In another example, described below in connection with FIG. 8, instead of constructing the coaxial coupling structure 380 at opposite ends with a metal post process and attaching the ends with conductive epoxy 60a, the coaxial coupling structure is in the form of an insertable coaxial plug having opposite ends attached to dielectric layers 42 and 52.

[0032] The top end of the outer conductor 382 is connected to the first metallization layer 367, and the bottom end of the outer conductor 382 is connected to the second metallization layer 369 and to each of the ground vias 72a and 72b. (The ground vias 72a and 72b are shown in phantom in FIG. 5.) The bonding to the first and second metallization layers 367 and 369 may be made in any suitable manner. For example, although shown adjacent to layers 367 and 369 in FIG. 4, portions of the first and second metallization layers 367 and 369 may be above and below the outer conductor 382, ​​and the ring portions 44b and 54b may be built with a metal pillar process on these portions of layers 367 and 369. It is noted here that there may be under bump metallization (UBM) between the top ring portion 44b and the dielectric layer 42, and between the bottom ring portion 54b and the dielectric layer 52 to further reduce the possibility of stress cracking above and below the region of the coaxial structure 380. Similarly, UBMs may be present between the top and bottom ends of coupling element 85 and adjacent dielectric layers.

[0033] Other components of the antenna apparatus 300, such as RF circuit(s) 32, RFIC(s) 30, antenna element(s) 20, probe feed 47, etc., may be the same as those described herein for the antenna apparatus 100. The dielectric layer 52 may be replaced with a multi-layer dielectric (comprising layers 52a, 52b) as shown in FIG. 3 to route RF signals to / from the RFIC 30.

[0034] 6 is a cross-sectional view illustrating an alternative coaxial coupling structure 380' that may be used in place of coaxial structure 380 in antenna apparatus 300. (FIG. 6 is a view of coaxial coupling structure 380' taken along line 5-5 of FIG. 4.) This embodiment may further reduce the occurrence of cracks in and near the coaxial coupling structure.

[0035] The coaxial coupling structure 380' differs from the coupling structure 380 by using a slotted outer conductor 393 instead of the outer conductor 382. The height (in the z-direction) of the coaxial structure 380' may be the same as the height of the coaxial structure 380. The outer conductor 393 has the general shape of a slotted hollow tube with a plurality of slots 391 circumferentially alternating with conductive wall sections 392. The wall sections 392 may each be formed between the dielectric layers 42 and 52 using the same metal post forming process used for the inner conductor 85. Thus, each wall section 392 may have upper and lower metal post forming sections attached together by a conductive adhesive layer portion (similar to layer portion 60a) therebetween. The upper and lower surfaces of each wall section 392 may be electrically connected to the first and second metallization layers 367 and 369, respectively. The isolation region 381 is desirably filled with a low-loss dielectric material. In one example, the slots 391 are filled with the same dielectric material as the dielectric material in the isolation region 381. This may be done prior to the insertion of the filler of the liquid filler layer 365 into the space surrounding the outer conductor 393. In another example, the slots 391 are filled with the filler of the filler layer 365. Either approach may result in fewer cracks during fabrication of the antenna device 300 because the outer conductor 393 may be more compliant and have a better CTE match with the surrounding structure than the outer conductor 383 which is constructed entirely of continuous metal.

[0036] 7 is a cross-sectional view of another alternative coaxial coupling structure 380'' that may be used in place of the coaxial coupling structure 380 in the antenna apparatus 300 (FIG. 7 is a view of the coaxial coupling structure 380'' taken along line 5-5 of FIG. 4). This embodiment, like the embodiment of the coupling structure 380', may reduce the occurrence of cracks compared to the embodiment involving the coaxial coupling structure 380.

[0037] The coaxial coupling structure 380' includes a plurality N of cylindrical ground rods 396_1 to 396_N as a replacement for the continuous outer conductor 382 of the coupling structure 380. In the example of FIG. 7, N=8, but in other examples, N is greater than 8 or is only 2. The length (in the z-direction) of the coaxial structure 380' may be the same as the length of the coaxial structure 380. The rods 396 may be uniformly spaced circumferentially just outside the periphery of the isolation region 381. The rods 396 may each be formed between the dielectric layers 42 and 52 using the same metal post forming process used for the inner conductor 85. Thus, each rod 396 may have upper and lower metal post forming sections attached together by a conductive adhesive layer portion (similar to layer portion 60a) therebetween. The upper and lower surfaces of each rod 396 may be electrically connected to the first and second metallization layers 367 and 369, respectively. The isolation region 381 is desirably filled with a low-loss dielectric material. Spaces 371 between adjacent rods 396 may be filled with the filler material of filler layer 365. This approach may result in fewer cracks occurring during fabrication of antenna apparatus 300, in that the interspersed structure of rods 396_1 through 396_N with compliant filler material therebetween may be more compliant than outer conductor 383 and a better CTE match with the surrounding structure.

[0038] In the minimum case of N=2, rod 396_1 is opposite rod 396_2 and forms a GSG connection extending from a lower GSG connection formed by ground vias 72a and 72b and signal via 70. In yet another example, coaxial coupling structure 380 is replaced with a GS connection including coupling element 85 and only one rod 396.

[0039] FIG. 8 is a perspective view of an alternative coaxial line section 380''' of the coaxial coupling element 380 of the antenna device 300. The coaxial line section 380''' may have an inner conductor 485 made of a continuous metal such as copper, an outer conductor 482 made of a continuous metal, and a dielectric spacer region 481 therebetween. When integrated into the antenna device 300 (prior to formation of the fill material layer 365), the top and bottom surfaces of the inner conductor 485 may be electrically connected to the probe feed 47 and the signal via 70, respectively. The top surface of the outer conductor 482 may be connected to the first metallization layer 367. The bottom surface of the outer conductor 482 may be connected to the second metallization layer 369 and each of the ground vias 72a and / or 72b. The dielectric fill layer 365 may surround the outer conductor 482 in the same manner as in the coaxial coupling structure 380.

[0040] FIG. 9 is a cross-sectional view of an antenna device 300′ including a filler with additional shielding structure according to one embodiment. The antenna device 300′ differs from the antenna device 300 by including multiple metal posts such as 344 and 354 formed on the first and second metallization layers 367 and 369, respectively. The metal posts 344 and 354 may be surrounded by the filler of layer 365 and may provide additional radiation shielding from radiation R for the circuitry below the base substrate 350. Thus, the improved radiation shield 364′ may include the first and second metallization layers 367 and 369, the filler material layer 365, and the metal posts 344 and / or 354. The metal posts 344 and 354 may have similar dimensions as the metal posts 44a and 54a. In some examples, such as shown in FIG. 9, the metal posts 344 are not electrically bonded to any vertically aligned metal posts 354 using a conductive adhesive such as 60a. In another example, vertically aligned metal pillars such as 344_1 and 354_1 are electrically bonded.

[0041] In some examples, the metal pillars are uniformly arranged in the xy plane and aligned vertically (in the z direction). For example, metal pillars 344_1 and 344_2 are vertically aligned with metal pillars 354_1 and 354_2, and each may be part of a uniform metal pillar grid distributed across metallization layers 367 and 369, respectively, in the xy plane. In other examples, the upper metal pillars 344 are staggered with respect to the lower metal pillars 354. For example, metal pillars 344_3 and 344_4 are staggered with respect to metal pillars 354_3 and 354_4. The layout of the metal pillars 344 and 354 may be optimized to achieve desired shielding performance based on the layout of the antenna element 120, the RFIC 30, other ICs (if present) under the base substrate 350, etc.

[0042] 10 is a bottom view of an antenna device 1000 showing an example layout of antenna elements and RFICs of a phased array antenna device according to an embodiment. The layout of the antenna device 1000 is an example layout of any one of the antenna devices 100, 200, 300, and 300' embodied as a phased array. In this example, the antenna device 1000 includes a plurality of N antenna elements 20_1 to 20_N forming an antenna array 120, a plurality of K RFICs 30_1 to 30_K (K≦N), and a coupler / divider network 181 with sections interspersed among the RFICs 30. The coupler / divider network 181 may be formed in a substrate 180, such as alumina, bonded to the bottom surface of the dielectric layer 52.

[0043] As shown in FIG. 10, in the xy plane, the radiation shield 1064 (e.g., radiation shield 64, 364, or 364′) may have a profile that is approximately coextensive with the profile of the antenna device 100. This allows the radiation shield 64 to shield all circuitry connected to or located below the surface of the dielectric layer 52. In addition to the RFIC 30, such circuitry may further include one or more control IC chips 160, which may be attached to the dielectric layer 52 and provide control / bias signals to the RFICs 30_1 through 30_K via signal lines 59. The control IC chip 160 may be composed of a different type of semiconductor material than the RFIC 30. For example, the control IC chip 160 may be composed of silicon (Si) or silicon germanium (SiGe), while the RFIC 30 may be composed of indium phosphate (InP), gallium arsenide (GaAs), or other types of III-V semiconductor materials. The peripheral shield 104 may surround the dielectric layers 52 and 42 and provide additional protection from incident radiation.

[0044] In the illustrated example, each RFIC, such as 30_1, is coupled to a plurality (N / K) of antenna elements (e.g., 20_1 and 20_2) through (N / K) RF circuits 32. RFIC 30 may further include (N / K):1 combiner / divider section 153 (e.g., a 2:1 combiner / divider) suitably coupled to combiner / divider 181. For example, combiner / divider 181 may be formed of a coplanar waveguide coupled to combiner / divider section 153 using wire bonds 141. In other examples, combiner / divider 181 or an alternative combiner / divider is formed in microstrip and / or coupled to combiner / divider section 153 through vias and signal paths formed in another layer, for example, a layer within dielectric layer 52 or a layer adjacent to the underside of RFIC 30. In a transmit antenna system, the combiner / splitter 181 may split an input signal received by the connector 170 into K split signals, each of which is provided to one of the RFICs 30 where it is further split for conditioning (e.g., amplification and phase shifting) and transmission through the antenna elements 120. Mutual coupling activities may occur in a receive antenna system.

[0045] 11 is a flow diagram illustrating an exemplary method 1100 of manufacturing an antenna device according to an embodiment. The method 1100 may be utilized to manufacture any one of the antenna devices 100, 200, 300, or 300'. The order of operations illustrated in FIG. 11 is not critical and may be changed as desired.

[0046] In the method 1100, an antenna substrate (e.g., 40 / 340) is formed (S1102). The antenna substrate may include a first dielectric layer (42), a first metallization layer (44 / 367) with a first opening (181a / 381a), and a probe feed via (47) if directly connecting to the antenna element. For the antenna device 100, if the coupling element 85 is formed in a metal post build-up process, the top metal post 44a may be formed layer-by-layer as part of the same process that forms the first metallization layer 44. On the other hand, to manufacture the antenna device 300 or 300', the first metallization layer 367 may be formed on the underside of the dielectric layer 42 by thin film deposition or by an initial metal build-up stage of a metal post build-up process. In the latter case, the initial metal build-up stage may also be the initial stage for manufacturing the top metal post (44a) and top ring portion (44b) of the coaxial line section (80 / 380). In other instances, the coupling element 85 may be part of a pre-formed coaxial structure, and the top metal post portion and the top ring portion may not be formed when the antenna substrate 40 / 340 is formed.

[0047] A base substrate (50 / 50' / 350) is formed (S1104) that includes a second dielectric layer (52, 52'), a second metallization layer (54 / 369) with a second opening (81b / 381b) aligned with the first opening, a signal via (70) in the dielectric layer, and at least one ground via (72a and / or 72b). Similar considerations as just described for the antenna substrate apply to the optional formation of the lower metal post 54a and lower ring portion 54b in conjunction with the formation of the second metallization layer.

[0048] For embodiments in which the first and second metallization layers (and coaxial coupling element layer portions, if applicable) are formed in a metal post build-up process, as described, for example, for antenna device 100, the process operations for forming the first and second metallization layers may be as follows, for a copper example: (i) form a copper seed layer on the surface of the respective dielectric layer (42 / 52) layers, (ii) use photoresist to define the perimeter of each of the metallization layers / posts to be formed, (iii) electroplate copper onto the copper seed layer, (iv) form a nickel diffusion barrier onto the electroplated copper, and (v) form a solder cap onto the nickel diffusion barrier. For metal layers comprised of alternative metals, such as platinum or gold, the alternative metals may be used in place of copper in the above operations.

[0049] In embodiments utilizing a pre-formed coaxial coupling structure (380'''), one end of the coupling structure may be attached, for example soldered, to the first or second dielectric layer (S1106).

[0050] At least one antenna element (20) is attached to the top surface of the antenna substrate and connected to the second ends of the probe feed vias (if included) (S1108). If the antenna element is a microstrip patch element, it may be formed on the antenna substrate by a thin film metal deposition process.

[0051] The antenna substrate is attached to the base substrate and the first metallization layer is attached to the second metallization layer (S1110). In the case of the antenna device 100, the antenna substrate and the base substrate may be attached simultaneously with the attachment of the first and second metallization layers using a conductive adhesive layer (60), e.g., a conductive epoxy or solder cap layer, between the first and second metallization layers, and further using a conductive adhesive (60a) between the upper and lower metal posts. In the case of the antenna device 300 / 300', the antenna substrate and the base substrate may be attached to each other by attaching the upper and lower metal posts (44a, 54a) to each other through a conductive adhesive before bonding the first and second metallization layers to each other.

[0052] When a separate outer conductor 382 is to be formed, the upper and lower metal post portions (44a, 54a) are attached at the same time that the upper and lower portions (44b, 54b) are attached to one another with the conductive adhesive portion (60b). It is further noted that if the coaxial structure is to be provided with a dielectric filled isolation region (381), the dielectric may be grown on the first / second dielectric substrate or placed in the opening 381 before connecting the antenna substrate and the base substrate to one another.

[0053] In embodiments where a pre-formed coaxial structure (380''') is used instead of a metal post-based structure, the antenna substrate and base substrate may become connected by connecting the unconnected end of the coaxial structure to the other of the base substrate and antenna substrate (S1110). In either of these cases (whether the coaxial coupling structure is metal post-based or a pre-formed structure), for antenna device 300 or 300', the metal post layer 365 may be formed after attaching the base substrate to the antenna substrate by inserting a filler material in liquid form into the space surrounding the coaxial coupling structure between the upper and lower metallization layers, and then heating the resulting structure to harden the filler material. Once the filler material has hardened, the first and second metallization layers may also be attached to each other.

[0054] At least one RFIC (30) is attached to the underside of the base substrate, for example, by electrically connecting signal and ground contacts (93s, 93g) to the signal and ground vias through respective heated and cooled solder caps (91). Additionally, this attachment may also include attaching additional contacts to the interconnects on the second dielectric layer for connecting signal lines (59) for carrying control / bias signals from a control IC.

[0055] While the technology described herein has been particularly shown and described with reference to exemplary embodiments thereof, those skilled in the art will understand that various changes in form and details may be made therein without departing from the scope of the claimed subject matter, as defined by the following claims.

Claims

1. An antenna device (100, 200, 300, 300', 1000), An antenna substrate (40, 340), a first dielectric layer (42) having opposing first and second surfaces; an antenna substrate including a first metallization layer (44, 367) adjacent said second surface to form a ground plane; At least one antenna element (20, 320) attached to the first surface; A base substrate (50, 50'), at least one second dielectric layer (52) having opposing third and fourth surfaces; a second metallization layer (54, 369) having a first side adjacent said third surface and an opposing, second side attached to said first metallization layer to form at least a portion of a radiation shield, said first and second metallization layers being aligned with one another and having first (81 a, 381 a) and second (81 b, 381 b) openings, respectively, underlying said at least one antenna element; and at least one radio frequency integrated circuit (RFIC) (32) adjacent the fourth surface of the base substrate, the radio frequency integrated circuit (RFIC) (32) being RF coupled to the at least one antenna element through at least one via (70) extending through the base substrate and coupling elements (85, 485) in the first and second openings.

2. 2. The antenna apparatus (100, 200, 300, 300', 1000) of claim 1, wherein the first and second metallization layers are attached and electrically connected through a conductive adhesive (60, 365) between the first and second metallization layers.

3. The antenna arrangement (100, 200, 300, 300', 1000) of claim 2, wherein the conductive adhesive is a material having a lower melting point than each of the first and second metallization layers.

4. The antenna arrangement (100, 200, 1000) of claim 2, wherein the conductive adhesive is a solder cap layer.

5. The antenna arrangement (100, 200, 1000) of claim 1, wherein the first metallization layer is a layer formed by a metal pillar build-up process.

6. The antenna arrangement (100, 200, 1000) of claim 5, wherein the second metallization layer is a layer formed by a metal pillar build-up process.

7. 7. The antenna arrangement (100, 200, 1000) according to any one of claims 5 or 6, wherein the metal pillar build-up process is a copper pillar build-up process, a platinum pillar build-up process or a gold pillar build-up process.

8. 2. The antenna arrangement (300, 300', 1000) of claim 1, wherein the first and second metallization layers are attached by a filler material layer (365) having a thickness greater than a thickness of each of the first and second metallization layers.

9. The antenna arrangement (300, 300', 1000) of claim 8, wherein the filler layer comprises a conductive epoxy, a conductive epoxy and tantalum mixture, an underfill material, a microwave absorbing material, or any combination thereof.

10. The antenna arrangement (300', 1000) of claim 9, wherein the filler layer further comprises a plurality of metal posts (344, 354).

11. The antenna arrangement (300', 1000) of claim 10, wherein at least some of the metal pillars (344_1, 344_2) are vertically aligned with others of the metal pillars (354_1, 354_2).

12. 2. The antenna device (100, 200, 300, 300', 1000) of claim 1, wherein the coupling element (85) includes a first metal post (54a) having one end attached to the via, a second metal post (44a) of a via having one end attached to the second surface of the first dielectric layer (42), and a conductive adhesive (60a) connecting a second end of the first metal post to a second end of the second metal post.

13. The antenna device (100, 200, 300, 300', 1000) of claim 12, further comprising a probe feed via (47) extending through the antenna substrate and having a first end connected to the antenna element, and a second end forming part of the second surface of the antenna substrate and connected to the first end of the second metal post.

14. The antenna arrangement (100, 200, 1000) of claim 1, wherein each of the first and second metallization layers is at least 50 μm thick.

15. The antenna arrangement (100, 200, 1000) of claim 1, wherein each of the first and second metallization layers is at least 100 μm thick.

16. The antenna arrangement (100, 200, 300, 300', 1000) of claim 1, wherein each of said at least one antenna element is a microstrip patch antenna element with a thickness in the range of 1 to 5 μm.

17. The antenna arrangement (100, 200, 300, 300', 1000) of claim 1, further comprising a radiation shield (104) extending around the antenna substrate and the base substrate.

18. The antenna arrangement (100, 200, 300, 300', 1000) according to claim 17, wherein the radiation shield is part of a metal housing.

19. The antenna arrangement (100, 200, 300, 300', 1000) of claim 1, wherein the at least one RFIC (30) is in the form of an RFIC chip or an RFIC wafer.

20. The antenna apparatus (100, 200, 300, 300', 1000) of claim 1, further comprising at least one further IC (160) attached to the fourth surface of the base substrate and configured to output control signals to the at least one RFIC.

21. the at least one antenna element being a plurality of antenna elements (20_1 to 20_N) forming an antenna array (120); the at least one RFIC being a plurality of RFICs (30_1 through 30_K) each attached to the fourth surface of the second dielectric layer; 2. The antenna apparatus (100, 200, 300, 300', 1000) of claim 1, wherein the plurality of RFICs are RF coupled to the plurality of antenna elements through respective RF feeds (70, 72a, 72b, 80, 380, 47) each including one of a plurality of vias (70) in the base substrate and one of a plurality of antenna feeds (47) formed in the antenna substrate.

22. 22. The antenna apparatus (200, 300, 300', 1000) of claim 21, wherein the at least one second dielectric layer of the base substrate comprises a first dielectric sublayer (52a) adjacent to the second metallization layer and a second dielectric sublayer (52b) adjacent to the RFIC, the base substrate further comprising a patterned conductive layer (98) between the first and second dielectric sublayers configured for routing RF signals to / from the RFIC.

23. each of the RF feeds is a ground-to-signal (GS) connection or a ground-to-signal-ground (GSG) connection; one of the vias (70) forming a signal via between the metal post (54a) of the third surface in the second opening and a signal contact (93s) of one of the RFICs; 22. The antenna arrangement (100, 200, 300, 300', 1000) of claim 21, comprising a ground-signal (GS) connection or a ground-signal-ground (GSG) connection comprising at least one ground via (72as, 72b) spaced apart from the signal via and extending between the third surface and at least one ground contact (93g) of the RFIC.

24. The antenna arrangement (100, 200, 300, 300', 1000) of claim 1, wherein the coupling element (85, 485) forms an inner conductor of a coaxial transmission line section (80, 380, 380', 380'', 380''').

25. 25. The antenna arrangement (100, 200, 300, 300', 1000) of claim 24, wherein the coaxial transmission line section includes an isolation region (81, 381, 481) filled with a dielectric material.

26. 25. The antenna apparatus (300, 300', 1000) of claim 24, wherein the coaxial transmission line section includes outer conductors (382, 393) each having an upper and lower portion formed by a metal post forming process, the upper and lower portions being connected by a conductive adhesive (60b).

27. 25. The antenna apparatus (300, 300', 1000) of claim 24, wherein the coaxial transmission line section (380') comprises an outer conductor (393) divided into a plurality of conductive wall sections (392).

28. The antenna arrangement (300, 300', 1000) according to claim 1, wherein the coupling element is disposed between a plurality of ground rods (396_1, 396_2).

29. 29. The antenna arrangement (300, 300', 1000) of claim 28, wherein the plurality of ground rods comprises at least three circumferentially disposed ground rods (396_1 to 396_N) surrounding the coupling element (85).

30. 25. The antenna apparatus (300, 300', 1000) of claim 24, wherein the coaxial transmission line section (380''') includes an inner conductor (485) comprised exclusively of a single metallic material and an outer conductor (482) comprised exclusively of a single metallic material.

31. A method (1100) for forming an antenna device (100, 200, 300, 300'), comprising the steps of: forming an antenna substrate (S1102) comprising a first dielectric layer having opposing first and second surfaces and a first metallization layer adjacent the second surface to form a ground plane for at least one antenna element, the first metallization layer having a first opening formed therein; Attaching at least one antenna element to the first surface of the antenna substrate (S1108); forming a base substrate (S1104) comprising at least one second dielectric layer having opposing third and fourth surfaces, at least one via extending through the second dielectric layer, and a second metallization layer adjacent the third surface for forming at least a portion of a radiation shield in conjunction with the first metallization layer, the second metallization layer having a second opening aligned with the first opening, at least one signal via having a first end in the second opening and extending through the second dielectric layer; Attaching the antenna substrate to the base substrate by at least connecting coupling elements in the first and second openings between the signal vias and the antenna substrate, and attaching the first metallization layer to the second metallization layer (S1110); and attaching (S1112) at least one radio frequency integrated circuit (RFIC) to the fourth surface of the base substrate and electrically connecting to the at least one signal via.

32. 32. The method (1100) of claim 31 , wherein the attaching of the first metallization layer to the second metallization layer is performed by adhering the first metallization layer to the second metallization layer with a conductive adhesive, the first metallization layer, the second metallization layer, and a layer therebetween formed by the conductive adhesive forming a radiation shield for the at least one RFIC.

33. 33. The method (1100) of claim 32, wherein the conductive adhesive is a solder cap.

34. 32. The method of claim 31, further comprising forming each of the first and second metallization layers by a metal pillar build-up process.

35. The metal pillar build-up process comprises: forming a copper seed layer on a surface of the first or second dielectric layer; defining a periphery of the copper pillar and the first or second metallization layer using photoresist; electroplating copper onto the copper seed layer; forming a nickel diffusion barrier on the electroplated copper; 35. The method of claim 34, including forming a solder cap on the nickel diffusion barrier.

36. 32. The method of claim 31, wherein each of the first and second metallization layers is formed to a thickness of at least 50 μm using a copper build-up process.

37. 32. The method of claim 31 , wherein after the antenna substrate is attached to the base substrate, the first and second metallization layers are attached to one another by inserting a liquid filler material into the area between the first and second metallization layers and allowing the filler material to harden.

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