PACKAGED ANTENNA AND METHOD FOR PRODUCING SAME
Electronic apparatus having an antenna chip with a substrate and an antenna structure, and a method of producing the same. The antenna chip is integrated or packaged in a package having a chip mounting surface for mounting the antenna chip, and an encapsulating material. The encapsulating material typically is a plastic mold used in the industrial packaging of integrated circuits. Between the antenna structure and the chip mounting surface, a first void is disposed in the substrate.
This application is a continuation of U.S. patent application Ser. No. 11/746,480, which was filed May 9, 2007. This application is incorporated herein by reference in its entirety.
BACKGROUNDThe present invention generally relates to apparatus and methods for packaging antenna devices and, in particular, apparatus and methods for packaging antenna chips to thereby form compact integrated radar, radio or wireless communications systems for high frequency applications.
Antenna structures are used in a variety of applications. Communication devices are equipped with antennas to enable wireless communication between devices in network systems such as wireless PAN (personal area network), wireless LAN (local area network), wireless WAN (wide area network), cellular network systems, and other types of radio systems.
Further applications include radar sensors, for example in the frequency range between 76 GHz and 81 GHz, which have gained importance in a variety of technical fields like automotive technology (collision avoidance, pre crash safety, etc.), motion sensoring in households and the like.
With conventional radar, radio or wireless communications systems, discrete components are individually encapsulated or individually mounted with low integration levels on printed circuit boards, packages or substrates. This usually causes significant losses at those high operating frequencies. At the same time, the miniaturization of the systems becomes more important, as robustness and reliability are required in the respective environments. Accordingly, there is a desire to package these electronic devices more densely. This, however, poses a number of challenges to designers, as high frequency appliances have to be integrated in hermetically closed packages while at the same time minimizing degrading effects on the emission characteristics and efficiency of the applied antennas.
Hence, there is a need for a technology to integrate antenna structures into a package and to improve the emission behavior of a radar antenna structures which are encapsulated in a package.
Embodiments of the invention will be described below with reference to exemplary embodiments which are shown in the appended figures. However, the invention is not restricted to the specifically described exemplary embodiments but rather may be modified and varied in a suitable manner. It is within the scope of the invention to combine individual features and combinations of features of one exemplary embodiment with features and combinations of features of another exemplary embodiment.
A first aspect of the present invention provides an electronic apparatus which includes an antenna chip or a chip that accommodates an antenna as well as other active and passive circuitries. The chip includes a substrate and an antenna structure. The apparatus further includes a package having a chip mounting surface and an encapsulating material. A first void is arranged in the substrate in the vicinity of the antenna structure.
In a second aspect of the present invention, an electronic apparatus is provided, which includes an antenna chip having a substrate and an antenna structure with optional active/passive circuitries. The apparatus further includes a package which includes a chip mounting surface and an encapsulating material, and a cap covering the antenna structure. A second void is arranged between the antenna structure and the cap.
A third aspect of the present invention provides a method of producing an electronic apparatus comprising an antenna chip and a package. The method includes the steps of providing a substrate, producing an antenna structure on an upper face of the substrate, producing a first void in the substrate, disposing the substrate on a chip mounting surface of the package, and providing a encapsulating material to seal the package.
In a fourth aspect of the present invention, there is provided a method of producing an electronic apparatus comprising an antenna chip and a package. The method includes the steps of providing a substrate, producing an antenna structure on an upper face of the substrate, disposing a cap on the upper face of the substrate covering the antenna structure, disposing the substrate on a chip mounting surface of the package, and providing a encapsulating material to seal the package.
As a result of the use of an electronic apparatus with an antenna structure having one or more voids disposed in its vicinity, the emission characteristics of the antenna is improved.
In order to simplify understanding of the description, identical reference numbers are used below when identical elements which are used together in the figures are involved. Elements in one embodiment may also be used in another embodiment without this being individually mentioned in each case.
The antenna structure 30 may be formed of any suitable material or combination of materials including, for example, dielectric or isolative materials such as fused silica (SiO2), silicon nitride, imides, pcb as supporting and/or embedding material and conducting materials like aluminium, copper, gold, titanium, tantalum and others or alloys of those conductors as active antenna materials. The antenna substrate 25 may be formed of semiconductor materials such as silicon, GaAs, InP, or GaN, especially if further circuit components are to be integrated into the antenna chip 20. Other types of substrate like glass, polystyrene, ceramics, Teflon® based materials, FR4 or similar materials are also included.
The present invention thus relates to the practice of disposing at least one void adjacent to an antenna structure. This significantly improves the emission and/or receiving characteristics of the antenna and thus allows reducing the applied power to achieve a certain radiated power or in case of receiving allows for a improved signal to noise figure. At the same time, homogeneity of the field distant from the antenna is improved. Furthermore, the electronic apparatus 10 allows for a dense package of the antenna structure which leads to the further miniaturization of the overall systems which use the antenna structure. Despite the dense package the emission and/or receiving characteristics of the antenna is improved and the mechanical robustness and reliability of the antenna structure can be guaranteed.
In an embodiment of the invention, the first void 100 is produced by etching the substrate 25 under the antenna structure 30. In case of silicon substrates the first void is preferably formed by a bulk etching process from a bottom surface of the substrate opposite to the antenna structure. The silicon bulk etching process can be performed by using a TMAH of KOH wet etch process or a plasma etching to etch off the bulk silicon.
The first void 100 typically has a size similar or larger to that of the antenna structure 30. Preferably, when the shape of the first void is projected vertically on the antenna structure, it is about 1/10 larger than the largest dimension of the antenna. Voids which are significantly larger than the antenna structure may also be used. The void may also be segmented, e.g. to improve mechanical stability of the assembly.
In a further embodiment of the invention shown in
There are a variety of options to realize a second void. In an embodiment of the present invention, an additional cap 70 is placed on the antenna structure 30 before the packaging of the apparatus, i.e. prior to the application of the encapsulating material 60 or mold mass. A suitable cap for this purpose is for example a SU8 frame. In a further embodiment of the present invention, the second void is realized by using the encapsulation material in the form of an encapsulating lid 65 (
In another embodiment of the invention shown in
In the embodiment shown in
The circuit 120 may be accompanied by an additional resonator chip 130 to filter the received signals, which can for example be a bulk acoustic wave filter or a DR filter etc.
In order to achieve a high level of integration of the electronic components on circuit 120, it is preferably, but not necessarily realized in SiGe-technology.
Furthermore, the present invention may also be employed in connection with radar sensors. Due to the small wavelengths occurring in the target operation frequency range of about 76 to 81 GHz, very small antennas can be used in the present invention. A typical antenna area is smaller than 2 mm2.
In a further embodiment of the invention, the circuit 120 and the antenna chip 20 are integrated on a single chip using a single substrate, which can contribute to further miniaturize the electronic apparatus and to reduce production costs. However, depending on technical requirements, chosen operating parameters and the like, it can be advantageous to employ separate chips for the antenna and the circuit as described above.
The antenna structure 30 of the present invention can be used to work as a radar antenna according to a variety of principles, which are continuous wave, continuous wave/Doppler, Frequency Modulated Continuous Wave (FMCW), and pulsed mode. Of those, continuous wave and continuous wave/Doppler are most common. The FMCW mode is suitable to detect the distance to a target object, whereas pulsed mode may be preferred if energy consumption of the sensor should be minimized.
As can be seen from
In case the encapsulating material is plastic mold compound (
Due to the small size of the antenna structure 30, it is possible to design the electronic apparatus of the present invention with a very small volume of only a few mm3. A preferred package for small electronic systems is the Thin Small Leadless Package (TSLP). Accordingly, in an embodiment of the invention the apparatus of the present invention comprises a TSLP package. A suitable TSLP package is available from Infineon Technologies, Munich, Germany. The height of the package is 0.4 mm, width 1.5 mm and length 2.3 mm.
The electronic apparatus of the present invention may be used in other frequency ranges and is not limited to the range from about 76 to 81 GHz as described.
A combination of
The electronic apparatus shown in
In order to allow the radiation to be emitted in the direction of the back side of the antenna chip the chip mounting surface 50 comprises openings 55 adjacent to the void 100 in the antenna substrate 25.
In the embodiment of the invention shown in
The package shown in
It is to be understood that the exemplary electronic apparatus depicted in
Claims
1. An apparatus, comprising:
- a chip comprising a semiconductor substrate and an antenna structure provided at a front side of the chip;
- a chip package comprising an encapsulating material; and
- a void arranged in the semiconductor substrate below the antenna structure, wherein the apparatus is configured to provide radiation in the direction of the front side of the chip.
2. The apparatus of claim 1, wherein a vertical projection of the void onto the antenna structure has substantially the same largest diameter as the largest diameter of the antenna structure or a larger diameter than the largest diameter of the antenna structure.
3. The apparatus of claim 1, wherein the largest dimension of the shape of the first void, as projected vertically on the antenna structure, is approximately ten percent larger than the largest dimension of the antenna
4. The apparatus of claim 1, further comprising:
- a high frequency circuit that is integrated in the chip.
5. The apparatus of claim 1, wherein the antenna structure has a size smaller than 2 mm2.
6. The apparatus of claim 1, further comprising:
- a chip package comprising an encapsulating material and a chip mounting structure, wherein the chip is mounted with a backside to the chip mounting structure.
7. The apparatus of claim 6, further comprising:
- a high frequency circuit chip, which is mounted to the chip mounting structure.
8. The apparatus of claim 6, further comprising:
- a further void in the encapsulating material, wherein the antenna structure is arranged between the void and the further void.
9. The apparatus of claim 8, further comprising:
- a cap covering the antenna structure at the front side of the chip; and
- a further void disposed between the antenna structure and the cap; wherein the antenna structure is arranged between the void and the further void.
10. The apparatus of claim 8, wherein the encapsulation material has a form of an encapsulating lid that is not in direct contact with the antenna chip to form the further void is formed.
11. An apparatus comprising:
- a chip comprising a semiconductor substrate and an antenna structure provided on a front side of the chip;
- a chip package comprising an encapsulating material and a chip mounting structure, wherein the chip is mounted with a backside to the chip mounting structure;
- a void in the semiconductor substrate; and
- a further void in the encapsulating material, wherein the antenna structure is arranged between the void and the further void, wherein the apparatus is configured to provide radiation in the direction of the back side of the chip.
12. The apparatus of claim 11, further comprising:
- a cap that is placed on the antenna structure at the front side of the chip, the cap having a conducting inner surface to reflect radiation emitted from the antenna structure.
13. The apparatus of claim 12, wherein the cap has a height that is a quarter of an operating wavelength of the radiation emitted from the antenna structure.
14. The apparatus of claim 11, wherein the chip mounting structure comprises at least one opening adjacent to the void in the semiconductor substrate to allow radiation being emitted in the direction of the back side of the chip.
15. The apparatus of claim 11, wherein the chip package further comprising a lead frame, which forms the chip mounting structure.
16. The apparatus of claim 11, further comprising:
- a high frequency circuit that is integrated in the chip.
17. The apparatus of claim 11, further comprising:
- a high frequency circuit chip, which is mounted to the chip mounting structure.
Type: Application
Filed: Jul 23, 2015
Publication Date: Nov 19, 2015
Inventors: Gerhard Lohninger (Munich), Johann P. Forstner (Steinhoering), Rudolf Lachner (Ingolstadt)
Application Number: 14/807,417