JP3565214B2 - Millimeter wave module - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-frequency module using millimeter waves or microwaves and a wireless device using the module.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a millimeter-wave waveguide using a silicon substrate by anisotropic etching, a waveguide described in IEEE MTT-S Digest, pp. 797 to 800, 1996 is known.
[0003]
FIG. 9 shows a structure of a conventional millimeter wave waveguide. Silicon dioxide 902 (SiO 2) is laminated on a silicon substrate 901, and a microstrip line 903 is formed thereon. A shielded microstrip line is formed with a structure sandwiching the silicon substrate 901 by using a carrier substrate 904 on which a metal is stacked and a micromachined silicon substrate 905 to obtain a shield structure.
[0004]
[Problems to be solved by the invention]
In this millimeter-wave waveguide, since the microstrip line is supported by silicon dioxide and floated in a hollow state, it is difficult to make a module in which other millimeter-wave components such as an MMIC are mounted. There is also a problem in strength. In addition, there is a problem that a processing process is complicated because it is necessary to perform processing by a micromachine on two silicon substrates and form a considerably thick silicon dioxide film in order to obtain strength.
[0005]
An object of the present invention is to solve the above-mentioned problem, to realize a millimeter-wave module in which a low-loss filter, an MMIC, and the like are mixed by simple processing, and to provide an inexpensive wireless device using millimeter waves and microwaves. With the goal.
[0006]
[Means for Solving the Problems]
In order to solve this problem, the present invention provides a first silicon single crystal substrate, in which rectangular first and second depressions are provided by anisotropic etching, and bottom and side surfaces of the first and second depressions. A second dielectric substrate having a conductor laminated as a ground plane, first and second coplanar lines provided as input / output lines, and a conductor laminated as a ground plane, and the first silicon substrate, First and second cavity resonators formed by joining to cover the second hollow are provided on a part of a ground surface provided on the second dielectric substrate. A third coplanar line for coupling the coplanar line with the first cavity resonator, a fourth coplanar line coupling between the first and second cavity resonators, and the second coplanar line; Fifth coplanar for coupling with the second cavity resonator Is obtained by the millimeter wave module, characterized in that a and road.
[0007]
As a result, a millimeter-wave module in which a low-loss filter and an MMIC are mounted together can be obtained by a simple processing method.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
According to the first aspect of the present invention, first and second depressions having a rectangular shape are provided on a first silicon single crystal substrate by anisotropic etching, and bottom surfaces of the first and second depressions are provided. A second dielectric substrate having the conductor laminated as a ground surface on the side surface, first and second coplanar lines provided as input / output lines, and a conductor laminated as a ground surface is formed by the first silicon substrate and the first dielectric substrate. , Having first and second cavity resonators formed by bonding so as to cover the second depressions, wherein the first and second cavity resonators are provided on a part of a ground surface provided on the second dielectric substrate. , A third coplanar line for coupling with the first cavity resonator, a fourth coplanar line for coupling between the first and second cavity resonators, and the second coplanar line. And a fifth coplanar line for coupling with the second cavity resonator A millimeter wave module, characterized in that a preparative, an effect that a high Q characteristic of the cavity resonator, with a low-loss filter can be realized, connected to other MMIC or the like can be facilitated.
[0009]
According to a second aspect of the present invention, there is provided a wireless device using the millimeter-wave module according to the first aspect, and an inexpensive wireless device is realized by using a millimeter-wave module formed by a simple processing method. Has the effect of being able to.
[0010]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0011]
(Embodiment 1)
FIG. 1 is a conceptual diagram showing the structure of a millimeter wave module according to the present embodiment, in which FIG. 1A is a sectional view and FIG. 1B is a perspective view. In FIG. 1, 101 is a silicon substrate, 102 is a recess formed by anisotropic etching, 103 is a ground metal layer laminated in the recess, 104 is air, 105 is a gold microbump for mounting, 106 is a millimeter-wave MMIC, 107 Is a glass substrate, 108 is a coplanar line, 109 is a metal wiring of a microstrip filter, and 110 is a bias pad for supplying a bias to the MMIC.
[0012]
With such a structure, most of the electric field of the microstrip filter is concentrated on the air layer 104a having no dielectric loss, so that the filter can be reduced in loss.
[0013]
In addition, the recess 102b is provided in the silicon substrate 101 immediately below the millimeter-wave MMIC to be flip-chip mounted, and the air layer 104b is provided near the active element. Therefore, it is possible to suppress the characteristic deterioration due to the flip-chip mounting.
[0014]
Further, by using a coplanar line for the connection between the glass substrate 107 and the MMIC 106, the process steps for the silicon substrate 101 can be simplified.
[0015]
By using the millimeter-wave module manufactured by such a simple method, an inexpensive wireless device can be realized.
[0016]
Although the configuration of the filter and the MMIC has been described as the present embodiment, a plurality of filters and the MMIC may be variously combined. Further, in the present embodiment, the recess is formed by anisotropic etching, but it is needless to say that a similar shape can be obtained by a dry etching method.
[0017]
(Embodiment 2)
2A and 2B are conceptual diagrams showing the structure of the millimeter-wave module according to the present embodiment. FIG. 2A is a sectional view, and FIG. 2 is different from the first embodiment in that a ground surface 111 is provided on the back surface of a glass substrate 107, and the ground surface is connected to the ground of the silicon substrate 101 via a through hole 112. Symbols other than the above are the same as those in FIG.
[0018]
With such a structure, the electric field generated in the vicinity of the microstrip filter 109 is shielded by being surrounded by the upper and lower grounds 103a and 111, so that the loss deterioration due to the radiation of the electric field can be suppressed. In addition, when the millimeter wave module of the present invention is mounted on a housing, it is possible to prevent the housing from affecting filter characteristics.
[0019]
By using the millimeter-wave module manufactured by such a simple method, an inexpensive wireless device can be realized.
[0020]
(Embodiment 3)
FIG. 3 shows a conceptual diagram of a cross-sectional structure of the millimeter wave module according to the present embodiment. FIG. 3 differs from the first embodiment in that instead of a silicon substrate, first ceramic substrates 201b and 201c having square holes and a second ceramic substrate 201a having no holes are bonded. The point is that the third ceramic substrate was formed, and the hollow shape similar to that of the silicon substrate was formed. 203a and 203b are respectively laminated as ground layers on the bottom surface of the depression, and an air layer 204 is formed by the depression. Other symbols are the same as those in FIG.
[0021]
With such a structure, the same effect as that of the first embodiment can be realized using an inexpensive ceramic substrate.
[0022]
Further, in the present embodiment, a two-layer structure of 201b and 201c is shown as the first ceramic substrate, and with such a structure, the thickness of the air layer is two for 204a and one for 204b. Layering can be easily performed, and the thickness of the air layer can be changed as necessary.
[0023]
Although the third ceramic substrate 201 has a three-layer structure in the present embodiment, it goes without saying that a similar effect can be obtained with a configuration having four or more layers.
[0024]
By using the millimeter-wave module manufactured by such a simple method, an inexpensive wireless device can be realized.
[0025]
(Embodiment 4)
FIG. 4 is a conceptual diagram of a cross-sectional structure of the millimeter wave module according to the present embodiment. 4 is different from the third embodiment in that a ground surface 205 is provided on a joint surface between a first ceramic substrate 201a having no holes and a second ceramic substrate 201b having holes, and a ground surface is provided on the bottom surface of the recess. The ground plane 203b and the ground plane 205 are connected by through holes 210, and the glass substrate 107 and the MMIC 106 can be connected by a microstrip line instead of a coplanar line. Other symbols are the same as in FIG.
[0026]
With such a structure, there is no converter between the coplanar line and the microstrip line, and the design is improved.
[0027]
By using the millimeter-wave module manufactured by such a simple method, an inexpensive wireless device can be realized.
[0028]
(Embodiment 5)
FIG. 5 shows a conceptual diagram of a cross-sectional structure of the millimeter wave module according to the present embodiment. FIG. 5 differs from the fourth embodiment in that a conductive metal 206 such as aluminum or brass is used instead of a ceramic substrate having no holes. Other symbols are the same as in FIG.
[0029]
With such a structure, the same effect as in the fourth embodiment can be obtained with a simple structure.
[0030]
By using the millimeter-wave module manufactured by such a simple method, an inexpensive wireless device can be realized.
[0031]
(Embodiment 6)
FIGS. 6A and 6B are conceptual views showing the structure of the millimeter-wave module according to the present embodiment. FIG. 6A is a sectional view and FIG. 6B is a perspective view. In FIG. 6, 301 is a glass substrate, 302 is a silicon substrate, 303 is a recess provided by anisotropic etching, 304 is a ground metal layer laminated in the recess, 305 is air, 306 is a gold microbump for mounting, 307 is a millimeter-wave MMIC, 308 is a coplanar line, 309 is a metal wiring of a microstrip filter, and 310 is a bias pad for supplying a bias to the MMIC.
[0032]
With such a structure, a microstrip filter using the air layer 305 as an insulating layer can be realized as in the first embodiment, and low loss of the filter can be realized.
[0033]
Further, if a rectangular hole 311 is provided in the glass substrate 301 immediately below the millimeter-wave MMIC 307 to be flip-chip mounted, air is provided close to the active element, so that deterioration in characteristics due to flip-chip mounting can be suppressed.
[0034]
By using the millimeter-wave module manufactured by such a simple method, an inexpensive wireless device can be realized.
[0035]
(Embodiment 7)
FIGS. 7A and 7B are conceptual views of the structure of the millimeter-wave module according to the present embodiment. FIG. 7A is a sectional view, and FIG. 7B is a perspective view. FIG. 8 is a conceptual diagram showing a surface structure of a glass substrate used in the millimeter wave module of FIG. In FIG. 7, 401 is a silicon substrate, 402 is a recess provided by anisotropic etching, 403 is a ground metal layer laminated in the recess, 404 is air, 407 is a glass substrate, 408a and 408b are provided on the silicon substrate 401. The first and second coplanar lines 409a and 409b are third and fourth coplanar lines provided on a glass substrate, respectively, and 410 is a fifth coplanar line provided on a glass substrate 407. Reference numeral 411 denotes a window on the silicon substrate 401 and the glass substrate 407 from which ground metal has been removed.
[0036]
The space confined by the recess 404 and the ground metal formed on the glass substrate acts as a cavity resonator that resonates one side of the recess 404 at a frequency near half the wavelength of free space. The cavity resonators are coupled by a fifth coplanar line wiring 410 provided on a glass substrate, and the input and output are coupled to the cavity resonators by third and fourth coplanar lines 409. By connecting to the first and second coplanar lines 408a and 408b serving as input / output lines, a cavity resonator filter having input and output coplanar line structures is realized.
[0037]
Since the cavity resonator has a high Q value, a low-loss filter can be realized. In addition, since the silicon substrate 401 and the glass substrate 407 are realized by anodically bonding the windows 411 provided on the respective ground wirings, the accuracy in the height direction of the air layer 404 is high, and the desired resonance frequency Can be realized with high accuracy.
[0038]
Further, since the input and output have a coplanar structure, connection with other components such as an MMIC can be easily realized.
[0039]
By using the millimeter-wave module manufactured by such a simple method, an inexpensive wireless device can be realized.
[0040]
In this embodiment, the bonding method between the silicon substrate 401 and the glass substrate 407 is anodic bonding, but it goes without saying that the mounting method using gold microbumps described in other embodiments may be used.
[0041]
【The invention's effect】
As described above, according to the present invention, a low-loss filter can be realized on a quasi-planar structure by a simple processing method, connection with an MMIC or the like can be simplified, and both miniaturization and high performance are satisfied. An advantageous effect is obtained that a reduced millimeter-wave module and a wireless device using the same can be manufactured at low cost.
[Brief description of the drawings]
FIG. 1A is a sectional structural view of a millimeter wave module according to an embodiment of the present invention; FIG. 2B is a conceptual perspective view of a millimeter wave module according to an embodiment of the present invention; FIG. FIG. 3B is a cross-sectional structural view of a millimeter wave module according to one embodiment; FIG. 3B is a structural diagram of the front and back surfaces of a glass substrate used in the millimeter wave module according to one embodiment of the present invention; FIG. 4 is a cross-sectional view of a millimeter-wave module according to an embodiment of the present invention. FIG. 5 is a cross-sectional view of a millimeter-wave module according to an embodiment of the present invention. a) Cross-sectional structural view of a millimeter wave module according to an embodiment of the present invention (b) Conceptual perspective view of a millimeter wave module according to an embodiment of the present invention [FIG. 7] (a) According to an embodiment of the present invention Cross-sectional structure of millimeter wave module (B) Conceptual perspective view of a silicon substrate used for a millimeter wave module according to one embodiment of the present invention. FIG. 8 is a structural diagram of a surface of a glass substrate used for a millimeter wave module according to one embodiment of the present invention. 9 Cross-sectional structure diagram of conventional millimeter-wave waveguide
101, 302, 401 Silicon substrate 102, 303, 402 Recess 103, 111, 203, 205, 304, 403 Ground plane 104, 204, 305, 404 Air layer 105, 306 Micro bump 106, 307 MMIC
107, 301, 401, 407 Glass substrate 108, 208, 308, 408, 409, 410 Coplanar line 109, 309 Microstrip type filter pattern 110, 310 Bias pad 112, 210 Through hole 201a Ceramic substrate having no square hole 201b, 201c Ceramic substrate 206 having square hole Conductive metal 311 Hole 411 Window

Claims (2)

First and second rectangular recesses are provided on a first silicon single crystal substrate by anisotropic etching, and conductors are stacked as ground planes on the bottom and side surfaces of the first and second recesses. First and second coplanar lines are provided as lines, and a second dielectric substrate on which a conductor is stacked as a ground surface and the first silicon substrate are joined so as to cover the first and second depressions. And the first coplanar line and the first cavity resonator are provided on a part of a ground plane provided on the second dielectric substrate. A third coplanar line for coupling, a fourth coplanar line for coupling between the first and second cavity resonators, and a coupling for coupling the second coplanar line with the second cavity resonator Characterized in that a fifth coplanar line is provided. Module. A wireless device using the millimeter-wave module according to claim 1.

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