# Patent

## Title
Electronic device with microfilm antenna and related methods

## Abstract

An electronic device may include a first substrate, an electrically conductive feed line on the first substrate, an insulating layer on the first substrate and the electrically conductive feed line, a second substrate on the insulating layer, and an antenna on the second substrate and having nanofilm layers stacked on the second substrate. The antenna is coupled to the feed line through an aperture.

## Background
RELATED APPLICATIONS
This application is a divisional application which is based upon prior filed copending application Ser. No. 13/755,803, filed Jan. 31, 2013, which is based upon prior filed provisional application Ser. No. 61/592,891 filed Jan. 31, 2012, the entire subject matter of which is incorporated herein by reference in its entirety


FIELD OF THE INVENTION
The present invention relates to the field of electronic devices, and, more particularly, to electronic devices with integrated antennas and related methods.
SUMMARY OF THE INVENTION
In view of the foregoing background, it is therefore an object of the present invention to provide electronic device with an integrated antenna that is robust.
This and other objects, features, and advantages in accordance with the present invention are provided by an electronic device comprising a first substrate, an electrically conductive feed line on the first substrate, an insulating layer on the first substrate and the electrically conductive feed line, a second substrate on the insulating layer, and an antenna on the second substrate and comprising a plurality of nanofilm layers stacked on the second substrate. Advantageously, the antenna may be integrated with other components on the first substrate.
More specifically, the electronic device may comprise an electrically conductive ground plane layer between the insulating layer and the second substrate. The insulating layer and the second substrate may define an aperture extending from the first substrate to the antenna for coupling the electrically conductive feed line to the antenna.
In some embodiments, each of the plurality of nanofilm layers comprises a carbon nanotube film layer configured to be electrically conductive. The electronic device further may comprise at least one integrated circuit (IC) component on the first substrate and coupled to the electrically conductive feed line.
For example, the insulating layer may comprise at least one of a silicon dioxide layer and a dielectric laminate layer. The first substrate may comprise at least one of a silicon layer, and a Gallium Arsenide layer. The second substrate may comprise a silicon layer, and a silicon dioxide layer.
Another aspect is directed to a method of making an electronic device. The method may comprise forming a first substrate, forming an electrically conductive feed line on the first substrate, and forming an insulating layer on the first substrate and the electrically conductive feed line. The method may also include forming a second substrate on the insulating layer, and forming an antenna on the second substrate, the antenna comprising a plurality of nanofilm layers stacked on the second substrate.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a schematic diagram of an exploded view of an electronic device, according to the present invention.
FIG. 1B is a cross-sectional view of a portion of the electronic device of FIG. 1.
FIG. 2 is a flowchart illustrating a method of making the electronic device of FIG. 1.
FIGS. 3-4 are charts illustrating performance of an example embodiment of the electronic device of FIG. 1.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
Referring now to FIGS. 1A-2, an electronic device 10 according to the present invention is now described. Also, with reference to flowchart 30, a method for making the electronic device 10 is also described, which starts at Block 31. The electronic device 10 includes a first substrate 11, an electrically conductive feed line 12 on the first substrate, and an insulating layer 13 on the first substrate and the electrically conductive feed line.
The electronic device 10 includes a second substrate 15 on the insulating layer 13, and an antenna 16 on the second substrate and comprising a plurality of nanofilm layers 19a-19c stacked on the second substrate. The first substrate 11 may comprise a silicon layer, or another semiconductor, such as a Gallium Arsenide layer. That is to say, in some embodiments, the first substrate 11 could comprise solely silicon or solely Gallium Arsenide, while in others, the Gallium Arsenide could comprise a combination thereof. The second substrate 15 may comprise a silicon layer, and a silicon dioxide layer.
More specifically, the electronic device 10 includes an electrically conductive ground plane layer 14 between the insulating layer 13 and the second substrate 15. For example, the insulating layer 13 may comprise at least one of a silicon dioxide layer, and a dielectric laminate layer. In the electronic device 10, the insulating layer 13 and the second substrate 15 define an aperture 18 extending from the first substrate 11 to the antenna 16 for coupling the electrically conductive feed line 12 to the antenna. In particular, the aperture (or via) 18 comprises a hallow aperture (i.e. air) for channeling electromagnetic waves, thereby coupling the electrically conductive feed line 12 to the antenna 16.
In some embodiments, each of the plurality of nanofilm layers 19a-19c comprises a carbon nanotube film layer configured to be electrically conductive. In other embodiments, each of the plurality of nanofilm layers 19a-19c comprises a metallic film layer (e.g. copper, aluminum, iron). The electronic device further comprises an IC component 22 on the first substrate 11 and coupled to the electrically conductive feed line 12. For example, the IC component 22 may comprise transceiver circuitry, i.e. amplifier, processor, etc. Additionally, each of the plurality of nanofilm layers 19a-19c has a thickness of less than 15 nm, and in some embodiments, less than 10 nm. In other words, this thickness value is in the nanometer range, ranging from several tens of nanometers to a few nanometers.
Another aspect is directed to a method of making an electronic device 10. The method may comprise forming a first substrate 11 (Block 33), forming an electrically conductive feed line 12 on the first substrate (Block 35), and forming an insulating layer 13 on the first substrate and the electrically conductive feed line (Block 37). The method may also include forming a second substrate 15 on the insulating layer 13 (Block 39), and forming an antenna 16 on the second substrate, the antenna comprising a plurality of nanofilm layers 19a-19c stacked on the second substrate (Blocks 41, 43).
An exemplary embodiment of the electronic device 10 is now described. A reliable and efficient system-on-chip, or an inter-chip wireless microwave or higher frequency data transfer system may necessitate the internal integration of an antenna with the integrated circuit. One approach to the integrated technique is to fabricate an antenna comprising nanomaterials that are compatible with the materials and fabrication procedure being used to fabricate the integrated circuit chip.
An aperture coupled microstrip antenna, where the active patch is composed of ultra-thin metallic nanofilms, such as 10 nm thick iron and 15 nm thick aluminum film, as well as vertically grown carbon nanotubes, has been demonstrated to work effectively. Such an antenna structure also provides an approach to the problems associated with making reliable direct electrical contacts to nanomaterials.
The antenna structure disclosed herein can be directly integrated into an IC using the materials used to fabricate the integrated circuit. FIG. 1A depicts a sketch of the antenna structure 10. A silicon IC technology is used in this description for convenience. The same description can be applied for other fabrication technologies, such as Gallium Arsenide based ICs.
The feed line connects 12 the IC 22 to the antenna structure 16. Depending on the specific fabrication method, the feed line 12 can comprise highly doped polysilicon or a metal line, deposited using the traditional or non-traditional fabrication procedures. On top of the feed line 12 is a layer of SiO2 13, which can be either grown or deposited. The ground plane 14 can either comprise highly doped polysilicon or a metal line, deposited using traditional or non-traditional procedures. The “aperture” or hole in the ground plane 14 is fabricated by etching or pre-defined in the mask used to develop the ground plane. The ground plane 14 is electrically connected to the electrical ground of the IC 22. On top of the ground plane 14 is deposited a layer of silicon to form an insulating layer 15. Polysilicon, SiO2, or even a combination of Si and SiO2 can also be used in place. A discussion shortly follows on how a combination of Si and SiO2 for this layer provides an additional degree of freedom in selecting the frequency of operation for such an antenna.
The patch 16 is the active radiating part of the antenna device 10, and comprises an ultra-thin metallic nanofilm, deposited using traditional or non-traditional fabrication procedures. For example, an aluminum film, a few nanometers to a few 10's of nanometers can be deposited using an EvoVac Deposition System, as available from Angstrom Engineering, Inc. of Kitchener, Ontario, Canada, where aluminum is thermally evaporated. Of course, other conventional devices that deposit thin film layers could be used.
Herein follows the results from simulating the performance of an antenna structure 10 shown in FIG. 1A. For the simulations, the following dimensions were considered: patch 16: 4.3 mm×5.9 mm; silicon substrate 18: 10 mm×10 mm×0.38 mm; silicon dioxide 13: 25 mm×20 mm×0.508 mm; Conducting feeding line: 15 mm×0.972 mm; and through-hole diameter: 0.8 mm. For the patch 16, an aluminum thin-film with a thickness of 50 nm was considered, where a bulk conductivity value of 38 MS/m, relative permittivity (sr) of 1, and relative permeability (pr) of 1.000021 were used.
FIG. 3 shows a diagram 50 including a curve 51 for the return loss of the antenna 10 as a function of frequency. As can be seen, the antenna 10 shows a return loss of over −20 dB at a frequency of 9.2 GHz, which makes it an excellent antenna. The frequency of operation of such an antenna can also be changed using the same fabrication technology, without changing the overall dimensions of the antenna. This can be accomplished through the use of a combination of different silicon based materials for layer 15 in FIG. 1A.
The simulation results are based upon using a combination of Si and SiO2 for layer 15 in FIG. 1A, instead of only Si. In some embodiments, the layer 15 may comprise Si/SiO2, and the SiO2 in layer 13 may comprise RT Duroid (done to demonstrate the effectiveness and versatility of aperture coupled ultrathin nanofilm antennas). The other materials remain the same.
FIG. 4 shows a diagram 60 of the return loss as a function of frequency for three different scenarios:

    1. (curve with circle mark) Layer 15 comprises only of Si with a thickness of 0.19 mm. This is done for comparison.
    2. (curve with wave mark) Layer 15 comprises Si on top of SiO2. Each has a thickness of 0.19 mm (?).
    3. (curve with dash mark) Layer 15 is composed of SiO2 on top of Si. Each has a thickness of 0.19 mm


All other dimensions remain the same as used to obtain the results in FIG. 3. As can be seen, the combination of different Si based materials, instead of only Si, can be used to control the frequency at which the antenna resonates.
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.

## Claims

1. A method for making a system-on-chip electronic device, the method comprising:
forming a first substrate;
forming an electrically conductive feed line on the first substrate;
forming an insulating layer on the first substrate and the electrically conductive feed line;
forming an electrically conductive ground plane layer on the insulating layer and defining an aperture;
forming a second substrate on the electrically conductive ground plane layer and covering the aperture;
forming an antenna on the second substrate, the antenna comprising at least one nanofilm layer stacked on the second substrate, each of the at least one nanofilm layer comprising a carbon nanotube film layer configured to be electrically conductive;
the aperture being hollow and for electrically coupling the electrically conductive feed line to the antenna; and
positioning an integrated circuit (IC) component on the first substrate and coupled to the electrically conductive feed line.

2. The method of claim 1 wherein the at least one nanofilm layer comprises a plurality of nanofilm layers.

3. The method of claim 1 wherein the insulating layer comprises at least one of a silicon dioxide layer and a dielectric laminate layer.

4. The method of claim 1 wherein the first substrate comprises at least one of a silicon layer and a Gallium Arsenide layer.

5. The method of claim 1 wherein the electrically conductive feed line comprises doped polysilicon.

6. The method of claim 1 wherein the electrically conductive feed line comprises a metallic material.

7. The method of claim 1 wherein the second substrate comprises silicon and silicon dioxide.

8. The method of claim 1 wherein the second substrate comprises a plurality of different silicon based materials.

9. The method of claim 1 wherein the IC component has an operational frequency of 9.2 GHz; and wherein the aperture has a diameter of 0.8 mm.

10. The method of claim 1 wherein each of the at least one nanofilm layer has a thickness of less than 15 nm.

11. A method for making a system-on-chip electronic device, the method comprising:
forming a first substrate;
forming an electrically conductive feed line on the first substrate;
forming an insulating layer on the first substrate and the electrically conductive feed line;
forming an electrically conductive ground plane layer on the insulating layer and defining an aperture;
forming a second substrate on the electrically conductive ground plane layer and covering the aperture;
forming an antenna on the second substrate, the antenna comprising a plurality of nanofilm layers stacked on the second substrate;
the aperture being hollow and for electrically coupling the electrically conductive feed line to the antenna; and
positioning an integrated circuit (IC) component on the first substrate and coupled to the electrically conductive feed line.

12. The method of claim 11 wherein each of the plurality of nanofilm layers comprises a carbon nanotube film layer configured to be electrically conductive.

13. The method of claim 11 wherein each of the plurality of nanofilm layers comprises a metallic film layer.

14. The method of claim 11 wherein the insulating layer comprises at least one of a silicon dioxide layer and a dielectric laminate layer.

15. The method of claim 11 wherein the first substrate comprises at least one of a silicon layer and a Gallium Arsenide layer.

16. The method of claim 11 wherein each of the plurality of nanofilm layers has a thickness of less than 15 nm.