U.S. patent application number 14/807417 was filed with the patent office on 2015-11-19 for packaged antenna and method for producing same.
The applicant listed for this patent is Infineon Technologies AG. Invention is credited to Johann P. Forstner, Rudolf Lachner, Gerhard Lohninger.
Application Number | 20150333395 14/807417 |
Document ID | / |
Family ID | 39969053 |
Filed Date | 2015-11-19 |
United States Patent
Application |
20150333395 |
Kind Code |
A1 |
Lohninger; Gerhard ; et
al. |
November 19, 2015 |
PACKAGED ANTENNA AND METHOD FOR PRODUCING SAME
Abstract
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.
Inventors: |
Lohninger; Gerhard; (Munich,
DE) ; Forstner; Johann P.; (Steinhoering, DE)
; Lachner; Rudolf; (Ingolstadt, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineon Technologies AG |
Neubiberg |
|
DE |
|
|
Family ID: |
39969053 |
Appl. No.: |
14/807417 |
Filed: |
July 23, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11746480 |
May 9, 2007 |
9103902 |
|
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14807417 |
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Current U.S.
Class: |
343/873 |
Current CPC
Class: |
G01S 7/03 20130101; H01L
2224/48091 20130101; H01Q 1/40 20130101; H01Q 1/38 20130101; Y10T
29/49016 20150115; H01Q 23/00 20130101; H01L 2224/48091 20130101;
H01L 2924/00014 20130101; H01Q 9/285 20130101 |
International
Class: |
H01Q 1/40 20060101
H01Q001/40 |
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 mm.sup.2.
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.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] 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.
BACKGROUND
[0002] The 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
BRIEF DESCRIPTION OF THE FIGURES
[0007] 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.
[0008] FIG. 1 shows a sectional view of a first embodiment of the
present invention;
[0009] FIG. 2 shows a sectional top view of a first embodiment of
the present invention.
[0010] FIG. 3 shows a sectional view of another embodiment of the
present invention comprising a circuit;
[0011] FIG. 4 shows a circuit diagram showing a part of a circuit
according to an embodiment of the present invention;
[0012] FIG. 5 shows a sectional view of another embodiment of the
present invention;
[0013] FIG. 6 shows a sectional view of another embodiment of the
present invention;
[0014] FIG. 7 shows a sectional view of further embodiment of the
present invention;
[0015] FIG. 8 shows a sectional view of still another embodiment of
the present invention;
[0016] FIG. 9 shows a typical, simplified block diagram of a
monostatic FMCW radar sensor used for the present invention;
[0017] FIG. 10 shows a typical, simplified block diagram of a data
transmitter used for the present invention;
[0018] FIG. 11 shows a typical, simplified block diagram of a data
receiver used for the present invention;
[0019] FIG. 12 shows a sectional view of further embodiment of the
present invention; and
[0020] FIG. 13 shows a sectional top view of the embodiment shown
in FIG. 12.
DETAILED DESCRIPTION OF THE INVENTION
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] FIG. 1 shows a first embodiment of the present invention.
FIG. 1 shows an electronic apparatus 10 having an antenna chip 20
with a substrate 25 and an antenna structure 30. The antenna chip
20 is integrated or packaged in a package 40 having a conducting
chip mounting surface 50 for mounting the antenna chip, and an
encapsulating material 60. The encapsulating material may be, but
is not limited to a typical plastic mold used in the industrial
packaging of integrated circuits. Between the antenna structure 30
and the chip mounting surface 50, a first void 100 is arranged in
the substrate 25 in the vicinity of the antenna structure 30. The
substrate height may be adjusted to the individual operating
wavelength. Preferably, substrate height is a quarter of the
operating wavelength to support radiation in the direction of the
front side of the antenna chip.
[0028] 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 (SiO.sub.2),
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.RTM. based materials, FR4 or similar
materials are also included.
[0029] FIG. 2 shows a top sectional view of the above described
embodiment of the present invention. The shape of the antenna
structure 30 should be regarded as an example and as non-limiting.
The antenna structure 30 may take the form of a variety of antenna
types like Patch, Folded Dipole, Butterfly, Leaky wave, etc.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] In a further embodiment of the invention shown in FIG. 5,
the electronic apparatus further comprises a second void 110
disposed between the antenna structure 30 and the encapsulating
material 60. The second void serves to improve the emission
characteristics of the antenna, as without a void the encapsulating
material or mold would be in direct contact with the antenna
structure, which might worsen the emission/receiving
characteristics.
[0034] 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 (FIG. 7) that is
not in direct contact with the antenna chip 30.
[0035] In another embodiment of the invention shown in FIG. 3, the
electronic apparatus further comprises a high frequency circuit
chip 120 mounted to the chip mounting surface 50 of the package 40.
The circuit serves to provide signals to the antenna structure 30
and to receive signals from it. It may comprise further electronic
parts and components necessary to realize a radar, radio or
wireless communication system in combination with the antenna
structure, i.e. oscillators, mixers, frequency dividers, etc.
[0036] In the embodiment shown in FIG. 3 the high frequency circuit
chip 120 and the antenna chip 30 are connected via wirebonds
interconnects 125. In a further embodiment of the present invention
the high frequency circuit chip 120 and the antenna chip 30 are
connected via bumps in a flip chip configuration. For example the
filter circuit chip 120 might be placed upside down on top of the
antenna chip 20 outside the area of the antenna structure 30. A
combination of the antenna structure with active circuit blocks on
one common chip shall be another embodiment.
[0037] FIG. 4 shows a circuit diagram of the receiver part of a
communication circuit according to an embodiment of the invention.
This circuit should be regarded as a non-limiting example. It
comprises a Low-Noise-Amlifier (LNA) 200, a first mixer 210, an
intermediate frequency amplifier 220, a voltage controlled
oscillator 230, amplifiers 240, 250, 260, 270, 280, a first
frequency divider 310, a second frequency divider 320, and two
second mixers 330, 340. The circuit is connected to an external
phase locked loop 350.
[0038] 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.
[0039] 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.
[0040] 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 mm.sup.2.
[0041] 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.
[0042] FIG. 9 shows a radar transmitting and receiving circuit
integrated with antenna within one common Si substrate. The height
and caps of the voids above and/or below the antenna can be
adjusted to allow for preferred radiation and/or reception to the
top surface or bottom surface of the structure (FIG. 12, 13). In
case of radiation/reception to the bottom openings in the chip
carrier can be provided.
[0043] 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.
[0044] FIG. 6 shows another embodiment of the present invention.
FIG. 6 shows an electronic apparatus 10 having an antenna chip 20
with a substrate 25 and an antenna structure 30. The antenna chip
20 is integrated or packaged in a package 40 having a chip mounting
surface 50 for mounting the antenna chip, and an encapsulating
material 60. The encapsulating material may be, but is not limited
to a typical plastic mold compound used in the industrial packaging
of integrated circuits. Suitable mold compounds are for example CEL
9240 HF, EME G770I, EME G760D-F, KMC 2520L.
[0045] As can be seen from FIG. 7 the encapsulating material may,
as an alternative, also take the form of a lid 65, preferably a
metal lid, having an opening 66 for radiating the signal power. As
a further alternative the lid 65 does not comprise an opening 66
but, instead, chip mounting surface 50 comprises an opening
adjacent to the void 100 in the antenna substrate 25 similar to the
embodiment of the present invention shown in FIG. 12. Thereby, the
distance between the antenna structure and the lid is preferably a
quarter of the operating wavelength to support radiation in the
direction of the back side of the antenna chip.
[0046] In case the encapsulating material is plastic mold compound
(FIG. 6) a cap 70 is covering the antenna structure 30. A second
void is disposed between the antenna structure 30 and the cap 70.
The second void serves to improve the emission characteristics of
the antenna, as without a void the mold material 60 would be in
direct contact with the antenna structure, which might worsen the
emission characteristics. This embodiment can be combined with
other features according to the present invention as hereinbefore
described with respect to other embodiments.
[0047] 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 mm.sup.3. 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.
[0048] 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.
[0049] FIG. 8 shows another embodiment of the present invention
using a Thin Small Leadless Package (TSLP). In order to connect the
package 40 to a printed circuit board (not shown) the package 40
comprises land interconnects 85. The antenna chip 20 is directly
connected to the contact lands 85 using wirebonds 125.
[0050] FIG. 9 shows a typical, simplified block diagram of a
monostatic FMCW radar sensor. A VCO 910, which can be connected to
an external PLL via a prescaler 920 and the tuning input 930,
generates the frequency ramps. A buffer amplifier 940 amplifies the
VCO output signal and isolates the VCO from the rest of the
circuit. The amplified signal is fed to a directional coupler 950
that feeds a part of the signal to the antenna 970 where it is
radiated and another part to the LO input of the mixer 960. The
incoming signal is fed from the antenna 970 to the coupler 950,
where a part is fed to the RF input of the mixer 960 where it is
demodulated. In a simpler implementation, the transmit receive
block 980 can also be a diode.
[0051] FIG. 10 shows a typical, simplified block diagram of a data
transmitter. A VCO 1010, which can be connected to an external PLL
via a prescaler 1020 and the tuning input 1030, generates the LO
signal. A buffer amplifier 1040 amplifies the VCO output signal and
isolates the VCO from the rest of the circuit. Via an optional
filter 1050, the LO signal is fed to the LO input to an
up-conversion mixer 1060, where the LO signal is modulated with a
data signal 1100. After filtering with a filter 1070 and
amplification 1080 the RF signal is fed to the antenna, where it is
radiated.
[0052] FIG. 11 shows a typical, simplified block diagram of a data
receiver. A VCO 1110, which can be connected to an external PLL via
a prescaler 1120 and the tuning input 1130, generates the LO
signal. A buffer amplifier 1140 amplifies the VCO output signal and
isolates the VCO from the rest of the circuit. Via an optional
filter 1150, the LO signal is fed to the LO input to a
down-conversion mixer 1160, where the via antenna 1190, filter 1180
and LNA 1170 incoming signal is demodulated.
[0053] A combination of FIG. 10 and FIG. 11 on one common chip is
also possible. This can be done with two individual antennas
located at opposite sides of the chip or by one common antenna
which is connected by a switch or a duplex filter to the transmit
and receive block.
[0054] FIG. 12 shows a further embodiment of the present invention.
FIG. 12 shows an electronic apparatus 10 having an antenna chip 20
with a substrate 25 and an antenna structure 30. The antenna chip
20 is integrated or packaged in a package 40 having a conducting
chip mounting surface 50 for mounting the antenna chip, and an
encapsulating material 60. Below the antenna structure 30 a first
void 100 is arranged in the substrate 25. In order to provide
additional mechanical stability to the antenna structure 30, the
antenna structure 30 is supported by a membrane 35 which separates
the antenna structure 30 from the first void 100 in the substrate
25. Preferably, the membrane is made of non-conducting material,
for example silicon oxide or silicon nitride. The membrane 35 may
also comprises several layers of the same or different
materials.
[0055] The electronic apparatus shown in FIG. 12 further comprises
a second void 110 disposed between the antenna structure 30 and the
encapsulating material 60. The second void 110 is provided by an
additional cap 70 that is placed on the antenna structure 30 before
the packaging of the apparatus, i.e. prior to the application of
the mold mass 60. A suitable cap for this purpose is for example a
SU8 frame that has been provided with conducting inner surface 75
to reflect the radiation emitted from the antenna structure 30. The
height of the cap 70 may be adjusted to the individual operating
wavelength. Preferably, height of the cap 70 is a quarter of the
operating wavelength to support radiation in the direction of the
back side of the antenna chip.
[0056] 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. FIG. 13 shows a corresponding sectional top
view of the embodiment shown in FIG. 12. Thereby, antenna opening
55a in lead frame is used to transmit radiation from the antenna
structure whereas antenna opening 55b in the lead frame is used to
receive radiation.
[0057] In the embodiment of the invention shown in FIG. 12, 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. Thereby, the circuit 120 is preferably a SiGe circuit.
[0058] The package shown in FIG. 12 is a Thin Small Leadless
Package (TSLP). In order to connect the package 40 to a printed
circuit board (not shown) the package 40 comprises land
interconnects 85. The antenna chip 20 is directly connected to the
contact lands 85 using wirebonds 125.
[0059] It is to be understood that the exemplary electronic
apparatus depicted in FIGS. 1-13 above can be constructed using
various types of chip fabrication and packaging technologies, and
that the invention is not limited to any specific chip fabrication
and packaging technologies discussed herein.
* * * * *