Antenna device 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 generally relates to antennas, and more specifically to an antenna device with a radiation shield for a radio frequency (RF) circuit integrated with an antenna element.

Background Art

[0002] In space, military, and some industrial environments, antenna elements and RF circuits coupled thereto can be exposed to radiation such as ionizing radiation, solar radiation, cosmic background radiation, wave radiation, particle radiation, and / or electromagnetic radiation. Without a proper shield, the RF circuit can be particularly vulnerable to radiation. For example, a thin, generally planar structure for an antenna device can have a sandwich-type configuration including an antenna element disposed in an outermost facing component layer and integrated circuits (ICs) dispersed across a parallel component layer behind the antenna element layer. The ICs can include RFICs with front-end circuits such as an RF power amplifier (PA) for transmission operations, a low noise amplifier (LNA) for reception operations, 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 can 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 can provide some radiation tolerance to the IC. However, certain types of high-intensity radiation can still penetrate the ground plane and degrade the IC, resulting in a reduction in the reliability of the antenna system.

Summary of the Invention

[0004] In one aspect of the present invention, the 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 for forming a ground plane. At least one antenna element is mounted on the first surface. The base substrate includes at least one 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 opposite second side attached to the first metallization layer for forming a radiation shield. The first and second metallization layers are aligned with each other and have first and second openings beneath the antenna element. At least one RFIC is positioned adjacent to the fourth surface of the base substrate and RF-coupled to 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 between them. In an alternative embodiment, the first and second metallization layers are attached by a filler layer having a thickness greater than the thickness of each of the first and second metallization layers.

[0006] In another embodiment, a method for 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 a second surface that forms 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 mounted on the first surface of the antenna substrate. A base substrate is formed, which includes 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 to the third surface to form at least a portion of a radiation shield together with the first metallization layer. The second metallization layer has a second opening aligned with the first opening. At least one signal via having a first end is formed extending through the second dielectric layer within the second opening. The antenna substrate is mounted to the base substrate by connecting at least coupling elements in the first and second openings between the signal via and the antenna substrate. The 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 at least one signal via. [Brief explanation of the drawing]

[0007] The above and other aspects and features of the disclosed technology will become more apparent from the following detailed description, together with the accompanying drawings in which similar reference letters indicate similar elements or features. Different elements of the same or similar kind may be distinguished by adding a reference label with an underline / dash and a second label that distinguishes them within the same / similar elements (e.g., _1, _2), or by directly adding a reference label with a 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] Figure 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 the IC of the antenna device. [Figure 2] Figure 2 is a cross-sectional view of the antenna apparatus in Figure 1, taken along line 2-2. [Figure 3] Figure 3 is a cross-sectional view of an antenna device having a multilayer base substrate according to one embodiment. [Figure 4] Figure 4 is a cross-sectional view of an antenna device, according to one embodiment, which includes a filler material that forms part of a radiation shield. [Figure 5] Figure 5 is a cross-sectional view of the antenna device shown in Figure 4, taken along line 5-5. [Figure 6] Figure 6 is a cross-sectional view of an alternative coaxial structure in which a coupling element is incorporated into the antenna device of Figure 4. [Figure 7] Figure 7 is a cross-sectional view of another alternative coaxial structure incorporating a coupling element within the antenna device of Figure 4. [Figure 8] Figure 8 is a perspective view of a further alternative coaxial structure incorporating a coupling element within the antenna device of Figure 4. [Figure 9] Figure 9 is a cross-sectional view of an antenna device including a filler and an additional shielding structure that form part of a radiation shield according to one embodiment. [Figure 10] Figure 10 is a plan view showing an example layout of a phased array antenna device according to one embodiment. [Figure 11] Figure 11 is a flowchart illustrating an exemplary method for manufacturing an antenna device according to another embodiment. [Modes for carrying out the invention]

[0009] For explanatory purposes, 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. The description includes various specific details to help those skilled in the art understand the technology, but these details should be considered merely illustrative. For the purposes of simplification and clarification, descriptions of well-known functions and structures may be omitted where their inclusion would obscure the understanding of the technology by those skilled in the art.

[0010] Figure 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 referred to as "RFIC 30"), such as a monolithic microwave IC (MMIC). Although one antenna element 20 and one RFIC 30 are shown, in various embodiments the antenna device 100 is configured as an active antenna array, such as a phased array, where multiple antenna elements 20 are arranged across the upper surface of the antenna substrate 40 (the xy plane in Figure 1) and multiple RFICs 30 are arranged across the lower surface of the base substrate 50. (In this specification, "upper" and "lower" are used as relative terms for ease of explanation and understanding. The upper surface of the antenna substrate 40 is the outer surface that connects to free space.) Each RFIC 30 is RF-coupled to at least one antenna element 20 through coupling structures in the base substrate 50 and the antenna substrate 40. In a typical embodiment, the antenna device 100 has a thin, plate-like profile whose maximum thickness (in the Z direction) is at least one 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 on which the antenna element 20 is attached, and a first metallization layer 44 adjacent to the lower surface of the dielectric layer 42. The first metallization layer 44 forms a ground plane for the antenna element 20 and may hereafter be referred to as the "ground plane 44". The base substrate 50 may include a second dielectric layer 52 with an upper and lower surface, and a second metallization layer 54 adjacent to its upper surface. The RFIC 30 is adjacent to the lower surface of the second dielectric layer 52. In some examples, the dielectric layers 42 and 52 are made 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 upper surface of the first dielectric layer 42. Such radiation R may take the form of ionizing radiation, wave radiation, particle radiation, solar radiation, cosmic microwave 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 and travels toward the RFIC 30.

[0013] In one example, the metallization layers 44 and 54 are formed by a metal column (or metal "bump") formation process, such as a copper column, gold column, or platinum column formation process. The adhesive 60 may be a solder cap layer and is typically thinner than each of the metallization layers 44 and 54. In one embodiment, each of the metallization layers 44 and 54 is at least 50 μm thick (thickness is in the z direction in Figure 1). In another embodiment, each of the layers 44 and 54 is at least 100 μm thick. For example, in space applications, it is desirable to protect from total ionization dose (TID) caused by radiation-induced charge generation / trapping. When the metallization layers 44 and 54 are each composed of a thick, dense material such as a pure metal such as copper, tantalum, or platinum, or a metal alloy, sufficient shielding can be provided to protect from this type of radiation. One way to design a suitable thickness for a given material is to consider the required lifespan of the antenna device 100 in its operating environment. When deployed on an orbiting satellite, a radiation dose depth curve correlated with the thickness of a given material required to attenuate the annual radiation level to a specific amount may be referenced. Specifications for the expected or minimum lifetime of the RFIC30 in a given radiation environment may also be considered. Based on this information, the thicknesses of the metallization layers 44 and 54, as well as the thickness and composition of the dielectric layer 52 of the base layer 50, can be designed.

[0014] As an example, in a conventional antenna device that does not utilize the attached metallization layers 44 and 54, the MMIC behind the antenna substrate 40 (e.g., directly mounted on the underside of the antenna substrate 40) can receive approximately 500 krad of radiation per year. In an antenna device 100 that incorporates a radiation shield 64 with a thickness of 100 μm containing copper and a dielectric layer 522 made of fused silica, the RFIC 30 can 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 can receive approximately 75 krad of radiation per year. Thus, in these examples, the total incident radiation over time is significantly reduced, thereby increasing the lifespan of the RFIC 30. In other examples, 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 will be further reduced. It should also be noted that fused silica is an example of a material that also provides considerable shielding against radiation. Therefore, when the dielectric layer 52 of the base substrate 50 is composed of fused silica or a similar material, it provides part of the radiation shield. For example, 250 μm fused silica has a density equivalent to copper of about 60 μm and can provide almost the same attenuation in radiation.

[0015] Generally, the thicknesses of the metallization layers 44 and 54 may be at least an order of magnitude greater than the thickness of the antenna element 20 (this thickness is exaggerated in Figure 1 relative to layers 44 and 54). In a typical embodiment, the antenna element 20 may be a printed element formed by a thin-film process. The antenna device 100 may also include a peripheral shield 104 (Schematically shown in Figure 1) surrounding the entire structure to reduce radiation incident from the periphery. The peripheral shield 104 may take 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 openings 81a and 81b located beneath the antenna element 20. A coupling element 85 may be formed in the center of the coaxial structure in the region of openings 81a and 81b. The coupling element 85 may include an upper metal column 44a, a lower metal column 54a, and a conductive adhesive 60a for conductively attaching the metal columns 44a and 54a. The metal columns 44a and 54a are parts of the metal column 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 can be understood as the internal conductor of a short coaxial transmission line ("coaxial line") 80, which will be described further below. The "signal via" 70 extends vertically through the base substrate 52 and at its lower end may be electrically connected to the "signal contact" 93s of the RFIC 30 through a conductive junction 91 such as a solder cap. The probe feed 47 may be a via formed through the first dielectric layer 42, with its lower end connected to the upper end of the metal column 44a and its upper end connected to the antenna element 20. Thus, the RFIC 30 can 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 lower 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 the coaxial wire 80 formed by the metal column process at the opposite end and attaching that end with conductive epoxy 60a, a pre-formed coaxial coupling structure in the form of an insertable coaxial wire section may be used as a substitute. This approach will be described below in reference to Figure 8. The insertable section may have the opposite end appropriately attached to the dielectric layers 42 and 52.

[0019] One or more ground contacts 93g of the RFIC 30 may be coupled to the second metallization layer 54 and the ground plane 44 (through the adhesive 60). Such coupling is performed 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 that include two or more ground vias 72a and 72b, 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 where 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] Figure 2 is a cross-sectional view of the antenna device 100 taken along line 2-2 in Figure 1. In Figure 2, exemplary profiles of the antenna element 20, RFIC chip 30, and first and second ground vias 72a and 72b are shown in phantom form. Referring collectively to Figures 1 and 2, an annular isolation region 81 surrounds the coupling element 85 and extends to the periphery 87 of the first and second metallization layers 44 and 54. The periphery 87 defines openings 81a and 81b in the first and second metallization layers 44 and 54. The isolation region 81 may be an air-filled region or it may be filled with dielectric material. The isolation region 81 can 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 between them (with the thickness of the adhesive 60). The coupling element 85, together with the separation region 81 and the circumferential edges 87 of the metallization layers 44 and 54, forms a coaxial line 80, where the coupling element 85 is the inner conductor, the circumferential edges 87 are the outer conductors, and the separation region 81 is a dielectric spacer or air-filled spacer for the coaxial line 80. There, radiation R can penetrate the separation region 81, but it should be noted that the diameter of the region 81 is small compared to the dimensions of the antenna device 100 in the xy plane, and therefore, penetrating radiation is likely to have little effect on the RFIC 30 and other circuits beneath the base substrate 50.

[0021] The above-described GSG transition between the RFIC 30 and the ground plane 44 can be understood as a GSG transition between the RFIC 30 and the coaxial line 80. The separation region 81 of the coaxial line 80 can be vertically aligned with the annular separation region 73 between the signal via 70 and the ground vias 72a and 72b. Thus, RF signal energy can flow through an RF feed surrounding the GSG transition, the coaxial coupling structure, and the antenna feed (probe feed 47 or EM coupling antenna feed) within the dielectric substrate 42. In other words, the signal energy flows from the RFIC 30 through the separation region 73, and the separation region 81, and the dielectric layer 42 to excite the antenna element 20. Note that additional ground vias (not shown) can be arranged at other circumferential positions adjacent to the outside of the edge 87 (viewed from points separated along the z-axis) to reduce signal leakage / noise.

[0022] The antenna element 20 can be a microstrip patch antenna element with a circular profile and can be offset-fed by the probe feed 47 as shown in FIG. 2. In other examples, the antenna element 20 has a rectangular, square, or other polygonal shape, or has a rectangular or irregular shape, or is a dipole or other type of antenna element. The patch antenna element can be formed by a thin film process and can have a thickness in the range of 1 to 5 μm. The RFIC 30 and its contact 93 are preferably arranged directly below 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 can include other circuits such as a coupler / distributor, an upconverter, a downconverter, etc.

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

[0024] The antenna device 100 may be configured as a transmitting antenna system, a receiving antenna system, or 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 embodiments where the RF circuit 32 includes a phase shifter for dynamic phase shifting of 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 directivity angle set primarily according to the phase shift of the phase shifter. Additional amplitude adjustment capability within the RFIC 30 may also be included to adjust the antenna pattern.

[0025] The RFIC chip 30 can 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 mounted on the underside 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 underside of the dielectric layer 52 (or formed in an additional thin dielectric layer on the underside of the dielectric layer 52) and connected to the RFIC chip 30 through an interconnect 58 (figuratively shown). These control IC chips may also be protected from incident radiation R by radiation shielding of the metallization layers 44 and 54. When multiple RFICs 30 are distributed across the entire underside of the dielectric layer 52, they may each be coupled to a coupler / divider network (not shown) for combining signals received by the antenna element 20 to form a received beam and / or splitting signals transmitted through the antenna element 20 to form a transmitted beam. The coupler / distributor network may be located within the transmission line substrate(s) between or beneath the RFIC30, or it may be formed by a patterned metal layer within the dielectric layer 52.

[0026] Figure 3 is a cross-sectional view of an antenna device 200 having a multilayer 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 the base substrate 50' includes a plurality of dielectric layers 52a and 52b, and a patterned metallization layer 98 between them. 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 coupler / distributor network for routing RF signals to / from the RFIC 30. The metallization layer 98 may, alternatively or additionally, be coupled to one or more control IC chips (not shown) that may be mounted on the underside of the dielectric layer 52b and provide bias / control signals.

[0027] Figure 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. Figure 5 is a cross-sectional view of the antenna device 300 taken along line 5-5 in Figure 4. Referring to Figures 4 and 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 cable) including a coupling element 85. To avoid redundancy, descriptions 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 the lower surface of the dielectric layer 42, the first metallization layer 367 functioning as the ground plane of the antenna element 20. The first metallization layer 367 may be thinner than the first metallization layer 44 in Figure 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 in Figure 1 and may be formed on the upper surface of the dielectric layer 52 by a process similar to that of the first metallization layer 367. The filler layer 365 may consist of a compliant material 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 has been integrated with the antenna substrate 340 and the base substrate 350. Therefore, the first and second metallization layers 367 and 369 can be attached to each other by the filler material layer 365.

[0029] Collectively, the first and second metallization layers 367 and 369 and the filler layer 365 form a radiation shield 364, reducing the effect of incident radiation R on the RFIC 30 and any other circuits beneath the base substrate 350. The filler layer 365 may also be a compliant material layer that reduces the possibility of cracking in the dielectric layers 42 and / or 52 during manufacturing. This allows the filler layer 365 to improve the manufacturing yield for the antenna device 100. For example, in the absence of the filler 365, a mismatch in the coefficient of thermal expansion (CTE) between the metal and the dielectric material could cause the thicker metal between the dielectric layers 42 and 52 to expand and contract at a higher rate than the dielectric layers 42 and 52. This CTE mismatch could lead to cracking if the antenna device is exposed to high temperatures. In contrast, the filler layer 365 may have a CTE close to that of the dielectric layers 42 and 52, thus preventing such cracking. Some examples of the composition of the filler layer 365 include conductive epoxy, a mixture of tantalum and conductive epoxy, microwave absorbers, and underfill materials. The selection of the material and thickness of the filler layer 365 may be made considering the desired radiation attenuation, as previously mentioned in relation to the metallization layers 44 and 54. For example, a radiation dose depth curve that correlates with the thickness of the material of the filler layer 365 required to attenuate the annual radiation level to a certain amount may be referenced. Due to its suitability, the filler layer 365 can also prevent cracking in the region surrounding the coaxial coupling structure 380, even when a thick metal is used for the surrounding outer conductor 382 (in the shape of a hollow tube or ring) that connects the coupling element 85 and the filler layer 365.

[0030] Vertically aligned openings 381a and 381b may be formed in the first and second metallization layers 367 and 369, respectively. The coaxial coupling structure 380, having portions inside and between the openings 381a and 381b, may include a coupling element 85, an outer conductor 382, ​​and an annular separation region 381. As previously stated, the coupling element 85 may include an upper metal column 44a, a lower metal column 54a, and a conductive adhesive 60a for electrically attaching the metal columns 44a and 54a.

[0031] The outer conductor 382 has the same thickness (in the z direction) as the coupling element 85 and can be formed simultaneously with the coupling element 85 using the same processing operation. Therefore, the outer conductor 382 may include an upper ring portion 44b formed by a metal column 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 column build-up process on the upper surface of the dielectric layer 52, and a conductive adhesive layer 60b to which the upper and lower ring portions 44b and 54b are attached. This structure allows the coaxial coupling structure 380 to 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 portions of the openings 381a and 381b, and a volume region 381c between them. The separation region 381 may be filled with a low-loss dielectric material and may be perpendicularly aligned with an annular separation region 73 between the signal vias 70 and ground vias 72a and 72b. In another example described below in relation to Figure 8, instead of constructing the coaxial coupling structure 380 at the opposite end using a metal column process and attaching that end with conductive epoxy 60a, the coaxial coupling structure takes the form of an insertable coaxial plug having the opposite end attached to dielectric layers 42 and 52.

[0032] The upper end of the outer conductor 382 is connected to the first metallization layer 367, and the lower end of the outer conductor 382 is connected to the second metallization layer 369 and to the ground vias 72a and 72b, respectively. (The ground vias 72a and 72b are shown as phantoms in Figure 5.) The coupling to the first and second metallization layers 367 and 369 can be done in any suitable manner. For example, although shown adjacent to layers 367 and 369 in Figure 4, parts of the first and second metallization layers 367 and 369 may be located above and below the outer conductor 382, ​​and the ring portions 44b and 54b may be constructed on these portions of layers 367 and 369 by a metal column process. It should be noted here that, in order to further reduce the possibility of stress cracking above and below the region of the coaxial structure 380, underbump metallization (UBM) may be present between the upper ring portion 44b and the dielectric layer 42, and between the lower ring portion 54b and the dielectric layer 52. Similarly, the UBM may be present between the upper and lower ends of the coupling element 85 and the adjacent dielectric layer.

[0033] Other components of the antenna device 300, such as the 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 device 100. The dielectric layer 52 may be replaced with a multilayer dielectric (comprising layers 52a and 52b) as shown in Figure 3, to which RF signals may be routed to and from the RFIC 30.

[0034] Figure 6 is a cross-sectional view showing an alternative coaxial coupling structure 380' that may be used in place of the coaxial structure 380 in the antenna device 300. (Figure 6 is a diagram of the coaxial coupling structure 380' obtained along line 5-5 in Figure 4.) This embodiment may further reduce the occurrence of cracks in the internal and nearby regions of 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 an outer conductor 382. The height (in the z direction) of the coaxial structure 380' may be the same as that of the coaxial structure 380. The outer conductor 393 has a general shape of a slotted hollow tube, with multiple slots 391 alternately arranged circumferentially with conductive wall sections 392. The wall sections 392 may be formed between the dielectric layers 42 and 52, respectively, using the same metal column forming process used for the inner conductor 85. Thus, each wall section 392 may have upper and lower metal column forming sections that are joined together by a conductive adhesive layer portion (similar to layer portion 60a) between them. 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 preferably 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 can be done before inserting the liquid filler layer 365 into the space surrounding the outer conductor 393. In another example, the slot 391 is filled with the filler layer 365. Either approach may result in fewer cracks occurring during the manufacture of the antenna device 300. This is because the outer conductor 393 may be more compatible than the outer conductor 383, which is made entirely of continuous metal, and has a better CTE match with the surrounding structure.

[0036] Figure 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 device 300 (Figure 7 is a diagram of the coaxial coupling structure 380'' obtained along line 5-5 in Figure 4). This embodiment, like the embodiment of coupling structure 380', may reduce the occurrence of cracks compared to the embodiment with the coaxial coupling structure 380.

[0037] The coaxial coupling structure 380' includes several N cylindrical ground rods 396_1 to 396_N instead of the continuous outer conductor 382 of the coupling structure 380. In the example in Figure 7, N=8, but in other examples, N is greater than 8 or only 2. The length of the coaxial structure 380' (in the z direction) may be the same as the length of the coaxial structure 380. The rods 396 may be arranged at uniform circumferential intervals just outside the isolation region 381. The rods 396 may be formed between the dielectric layers 42 and 52, respectively, using the same metal pillar formation process used for the inner conductor 85. Thus, each rod 396 may have upper and lower metal pillar formation sections that are joined together by a conductive adhesive layer portion (similar to layer portion 60a) between them. 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 preferably filled with a low-loss dielectric material. The space 371 between adjacent rods 396 may be filled with the filler material of the filler layer 365. This approach may reduce the occurrence of cracks during the manufacture of the antenna device 300, as the scattered structure of rods 396_1 to 396_N with compliant filler material in between is more conformable than the outer conductor 383 and can result in a better CTE match with the surrounding structure.

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

[0039] Figure 8 is a perspective view showing a coaxial cable section 380''' that replaces the coaxial coupling element 380 of the antenna device 300. The coaxial cable 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 between them. When integrated into the antenna device 300 (before the formation of the filler material layer 365), the upper and lower surfaces of the inner conductor 485 may be electrically connected to the probe feed 47 and the signal via 70, respectively. The upper surface of the outer conductor 482 may be connected to the first metallization layer 367. The lower surface of the outer conductor 482 may be connected to the second metallization layer 369 and to the ground vias 72a and / or 72b, respectively. The dielectric filler layer 365 may surround the outer conductor 482 in the same manner as in the coaxial coupling structure 380.

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

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

[0042] Figure 10 is a bottom view of antenna device 1000 showing an example layout of antenna elements and RFICs in a phased array antenna device according to one embodiment. The layout of antenna device 1000 is one example layout of antenna devices 100, 200, 300, and 300' embodied as a phased array. In this example, 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 / distributor network 181 with sections scattered among the RFICs 30. The coupler / distributor network 181 may be formed in a substrate 180 such as alumina bonded to the underside of the dielectric layer 52.

[0043] As shown in Figure 10, in the xy plane, the radiation shield 1064 (e.g., radiation shield 64, 364, or 364') may have a profile with substantially the same extent as the profile of the antenna device 100. This allows the radiation shield 64 to shield all circuits that are connected to or located below the surface of the dielectric layer 52. In addition to the RFIC 30, such circuits may further include one or more control IC chips 160, which are mounted on the dielectric layer 52 and may provide control / bias signals from RFIC 30_1 to 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 example shown, each RFIC, such as 30_1, is coupled to multiple (N / K) antenna elements (e.g., 20_1 and 20_2) through an (N / K):1 RF circuit 32. The RFIC 30 may further include an (N / K):1 coupler / distributor section 153 (e.g., a 2:1 coupler / distributor) appropriately coupled to a coupler / distributor 181. For example, the coupler / distributor 181 may be formed of a coplanar waveguide coupled to the coupler / distributor section 153 using wire bonds 141. In other examples, the coupler / distributor 181 or an alternative coupler / distributor is coupled to the coupler / distributor section 153 through vias and signal paths formed in a microstrip and / or another layer, e.g., a layer in the dielectric layer 52, or a layer adjacent to the underside of the RFIC 30. In the transmitting antenna system, the coupler / distributor 181 can divide the input signal received by the connector 170 into K divided signals, each of which is provided to one of the RFICs 30, where it is further divided for adjustment (e.g., amplification and phase shift) and transmission through the antenna element 120. In the receiving antenna system, mutual coupling operation may occur.

[0045] Figure 11 is a flowchart illustrating an exemplary method, 1100, for manufacturing an antenna device according to an embodiment. Method 1100 may be used to manufacture any one of the antenna devices 100, 200, 300, or 300'. The order of operations shown in Figure 11 is not critical and may be changed as needed.

[0046] In 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 first openings (181a / 381a), and probe feed vias (47) if directly connected to an antenna element. In the case of antenna device 100, if the coupling element 85 is formed by a metal column build-up process, the upper metal column 44a may be formed layer by layer as part of the same process as forming the first metallization layer 44. Alternatively, to manufacture 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 step of a metal column build-up process. In the latter case, the initial metal build-up step may also be the first step for manufacturing the upper metal column (44a) and upper ring portion (44b) of the coaxial line section (80 / 380). In other examples, the coupling element 85 is part of a pre-formed coaxial structure, and the upper metal column portion and the upper ring portion may not be formed when the antenna substrate 40 / 340 is formed.

[0047] A base substrate (50 / 50' / 350) is formed (S1104), which 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). Considerations similar to those just described for the antenna substrate are applied to the formation of the optional lower metal column 54a and lower ring portion 54b in conjunction with the formation of the second metallization layer.

[0048] In embodiments where the first and second metallization layers (and, where applicable, the coaxial coupling element layer portion) are formed by a metal column build-up process, the process operations for forming the first and second metallization layers may be as follows, in the example of copper, as described for antenna device 100: (i) forming a copper seed layer on the surface of each dielectric layer (42 / 52) layer; (ii) using photoresist to define the periphery of each metallization layer / pillar to be formed; (iii) electroplating copper onto the copper seed layer; (iv) forming a nickel diffusion barrier on the electroplated copper; and (v) forming a solder cap on the nickel diffusion barrier. In the case of metal layers composed of alternative metals, such as platinum or gold, the alternative metal may be used instead of copper in the above operations.

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

[0050] At least one antenna element (20) is mounted on the upper surface of the antenna substrate and connected to the second end of a probe feed via (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 antenna device 100, the antenna substrate and the base substrate may be attached simultaneously with the attachment of the first and second metallization layers by a conductive adhesive layer (60) between the first and second metallization layers, for example, a conductive epoxy or solder cap layer, and also by using a conductive adhesive portion (60a) between the upper metal column and the lower metal column. In the case of antenna device 300 / 300', the antenna substrate and the base substrate can be attached to each other by attaching the upper and lower metal columns (44a, 54a) to each other through the conductive adhesive portion before the first and second metallization layers are bonded to each other.

[0052] When a separate outer conductor 382 is to be formed, the upper and lower metal column portions (44a, 54a) are attached, and at the same time, the upper and lower portions (44b, 54b) can be attached to each other by a conductive adhesive portion (60b). If a dielectric-filled isolation region (381) is to be provided in the coaxial structure, it should be further noted that the dielectric may be grown on the first / second dielectric substrate or placed within the opening 381 before the antenna substrate and the base substrate are connected to each other.

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

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

[0055] While the technologies described herein are shown and explained with reference to exemplary embodiments, those skilled in the art will understand that various modifications of form and detail may be made therein without departing from the scope of the subject matter of the claims as defined below.

Claims

1. Antenna devices (100, 200, 300, 300', 1000), Antenna substrate (40, 340), A first dielectric layer (42) having opposing first and second surfaces, An antenna substrate comprising a first metallization layer (44, 367) adjacent to the second surface for forming a ground plane, At least one antenna element (20, 320) attached to the first surface, The base substrate (50, 50') A second dielectric layer (52) having opposing third and fourth surfaces, The base substrate (50, 50') includes a first side surface adjacent to the third surface and a second metallization layer (54, 369) having a second side surface that is attached to the first metallization layer to form at least a portion of the radiation shield, wherein the first and second metallization layers are aligned with each other and have first (81a, 381a) and second (81b, 381b) openings, respectively, located beneath the at least one antenna element. The system comprises at least one radio frequency integrated circuit (RFIC) (32) adjacent to the fourth surface of the base substrate, which is 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, The first and second metallization layers are attached to each other and electrically connected using conductive filler material layers (60, 365) between the first and second metallization layers. The conductive filler material layer has a thickness greater than the thickness of each of the first and second metallization layers. The conductive filler layer comprises conductive epoxy, a mixture of conductive epoxy and tantalum, an underfill material, a microwave absorber, or any combination thereof. An antenna device wherein the conductive filling material layer further comprises a plurality of metal pillars (344, 354).

2. The antenna device (100, 200, 300, 300', 1000) according to claim 1, wherein the conductive filling material layer has a lower melting point than each of the first and second metallization layers.

3. The antenna device (100, 200, 1000) according to claim 1, wherein the conductive filling material layer is a solder cap layer.

4. The antenna device (100, 200, 1000) according to claim 1, wherein the first metallization layer is a layer formed by a metal column build-up process.

5. The antenna device (100, 200, 1000) according to claim 4, wherein the second metallization layer is a layer formed by a metal column build-up process.

6. The antenna device (100, 200, 1000) according to any one of claims 4 or 5, wherein the metal column build-up process is a copper column build-up process, a platinum column build-up process, or a gold column build-up process.

7. The antenna device (300', 1000) according to claim 1, wherein at least some of the metal columns (344_1, 344_2) are aligned perpendicularly with the others of the metal columns (354_1, 354_2).

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

9. The antenna device (100, 200, 300, 300', 1000) according to claim 8, 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 a part of the second surface of the antenna substrate and connected to the first end of the second metal column.

10. The antenna device (100, 200, 1000) according to claim 1, wherein each of the first metallization layer and the second metallization layer has a thickness of at least 50 μm.

11. The antenna device (100, 200, 1000) according to claim 1, wherein each of the first metallization layer and the second metallization layer has a thickness of at least 100 μm.

12. The antenna device according to claim 1 (100, 200, 300, 300', 1000), wherein each of the at least one antenna elements is a microstrip patch antenna element having a thickness in the range of 1 to 5 μm.

13. The antenna device (100, 200, 300, 300', 1000) according to claim 1, further comprising a radiation shield (104) extending around the antenna substrate and the base substrate.

14. The antenna device (100, 200, 300, 300', 1000) according to claim 13, wherein the radiation shield is part of a metal housing.

15. The antenna device (100, 200, 300, 300', 1000) according to claim 1, wherein the at least one RFIC (30) is an RFIC chip or an RFIC wafer.

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

17. The at least one antenna element is a plurality of antenna elements (20_1 to 20_N) that form an antenna array (120), The at least one RFIC is a plurality of RFICs (30_1 to 30_K), each mounted on the fourth surface of the second dielectric layer. The antenna device (100, 200, 300, 300', 1000) according to claim 1, wherein each of the plurality of RFICs is RF coupled to the plurality of antenna elements through an RF feed (70, 72a, 72b, 80, 380, 47) which includes 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.

18. The antenna device (200, 300, 300', 1000) according to claim 17, 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, and the base substrate further comprises a patterned conductive layer (98) configured to route RF signals to and from the RFIC between the first and second dielectric sublayers.

19. Each of the RF feeds is a ground-signal (GS) connection or a ground-signal-ground (GSG) connection, One of the vias (70) that form a signal via between the metal column (54a) on the third surface within the second opening and the signal contact (93s) of one of the RFICs, Antenna device (100, 200, 300, 300', 1000) according to claim 17, comprising a ground-signal (GS) connection or a ground-signal-ground (GSG) connection, the ground-signal (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.

20. The antenna device (100, 200, 300, 300', 1000) according to claim 1, wherein the coupling elements (85, 485) form the internal conductors of the coaxial transmission line sections (80, 380, 380', 380'', 380'''').

21. The antenna device (100, 200, 300, 300', 1000) according to claim 20, wherein the coaxial transmission line section includes isolation regions (81, 381, 481) filled with dielectric material.

22. The antenna device (300, 300', 1000) according to claim 20, wherein the coaxial transmission line section includes outer conductors (382, 393) each having an upper and lower portion formed by a metal column forming process, and the upper and lower portions are connected by a conductive adhesive (60b).

23. The antenna device (300, 300', 1000) according to claim 20, wherein the coaxial transmission line section (380') includes an outer conductor (393) divided into a plurality of conductive wall sections (392).

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

25. The antenna device (300, 300', 1000) according to claim 24, wherein the plurality of ground rods comprises at least three ground rods (396_1 to 396_N) arranged in the circumferential direction surrounding the coupling element (85).

26. The antenna device (300, 300', 1000) according to claim 20, wherein the coaxial transmission line section (380''') includes an inner conductor (485) made of a single metal material and an outer conductor (482) made of a single metal material.

27. A method (1100) for forming an antenna device (100, 200, 300, 300'), An antenna substrate is formed comprising a first dielectric layer having opposing first and second surfaces, and a first metallization layer adjacent to the second surface for forming a ground plane for at least one antenna element, wherein a first opening is formed in the first metallization layer (S1102), At least one antenna element is attached to the first surface of the antenna substrate (S1108), A base substrate is formed 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 to the third surface for forming at least a portion of a radiation shield together with the first metallization layer, wherein the second metallization layer has a second opening aligned with the first opening, and at least one signal via having a first end extending through the second dielectric layer into the second opening (S1104). The antenna substrate is attached to the base substrate by connecting at least the coupling elements in the first and second openings between the signal via and the antenna substrate, and the first metallization layer is attached to the second metallization layer (S1110), This includes mounting at least one radio frequency integrated circuit (RFIC) to the fourth surface of the base substrate and electrically connecting it to at least one signal via (S1112), The attachment of the first metallization layer to the second metallization layer is performed by bonding the first metallization layer to the second metallization layer using a conductive adhesive filler material layer (60, 365). The conductive adhesive filler layer has a thickness greater than the thickness of each of the first and second metallization layers. The conductive adhesive filler layer comprises conductive epoxy, a mixture of conductive epoxy and tantalum, an underfill material, a microwave absorber, or any combination thereof. The method (1100) further comprises a plurality of metal pillars (344, 354) in the conductive adhesive filling material layer.

28. The method according to claim 27, wherein the first metallization layer, the second metallization layer, and the layer between them formed by the conductive adhesive filler layer form a radiation shield to the at least one RFIC.

29. The method according to claim 28, wherein the conductive adhesive filling material layer is a solder cap.

30. The method according to claim 27, further comprising forming each of the first and second metallization layers by a metal column build-up process.

31. The aforementioned metal column build-up process, Forming a copper seed layer on the surface of the first or second dielectric layer, Using a photoresist to define the area around the copper column and the first or second metallization layer, Electroplating copper onto the aforementioned copper seed layer, Forming a nickel diffusion barrier on the electroplated copper, The method according to claim 30, comprising forming a solder cap on the nickel diffusion barrier.

32. The method according to claim 27, 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.

33. The method according to claim 27, wherein after the antenna substrate is attached to the base substrate, a liquid filler is inserted into the region between the first and second metallization layers and the filler is cured, thereby attaching the first and second metallization layers to each other using a conductive adhesive filler layer.

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