JP2006311218A - Surface acoustic wave device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface acoustic wave device capable of suppressing the fluctuation of frequency characteristics due to the influence of stress after mounting. <P>SOLUTION: The surface acoustic wave device (1) is provided with surface acoustic wave elements (14, 16) provided on one surface side of a substrate (10), a groove (18) provided on at least one surface side of the substrate so as to surround the periphery of the surface acoustic wave elements, and a semiconductor circuit (24) having a function of controlling the operation of the surface acoustic wave elements and provided on the other surface side of the substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a device using a surface acoustic wave (SAW).

  A surface acoustic wave device (SAW device) is an element that utilizes a phenomenon in which a specific frequency is selected in the process of using a piezoelectric material, converting a high-frequency signal into a surface acoustic wave, and then converting it into a high-frequency signal again. Such SAW devices are used in various fields such as communication devices, sensors, touch panels, and the like, and are particularly essential in the field of mobile communication typified by mobile phones. Also, with the recent trend of integration of electronic components and reduction of mounting space, the combination of semiconductor circuits and SAW devices has been promoted. For example, in Japanese Patent Laid-Open No. 5-308163 (Patent Document 1), a piezoelectric substrate including a surface acoustic wave element and a semiconductor substrate including a semiconductor integrated circuit are stacked and integrated to achieve high integration and small size of the device. A SAW device (semiconductor surface acoustic wave composite device) is disclosed.

  However, when the composite SAW device is mounted on another circuit board or the like, stress is applied to each substrate constituting the SAW device, and the characteristics such as the resonance frequency of the surface acoustic wave element are affected by the stress. May cause fluctuations. Such inconvenience is particularly noticeable when the flip chip bonding method is adopted as the mounting method of the SAW device.

JP-A-5-308163

  Accordingly, an object of the present invention is to provide a surface acoustic wave device capable of suppressing fluctuations in frequency characteristics due to the influence of stress after mounting.

  According to the first aspect of the present invention, there is provided a surface acoustic wave element provided on one side of a substrate, a groove provided on at least one side of the substrate so as to surround the surface acoustic wave element, And a semiconductor circuit provided on the other surface side.

  According to this configuration, the stress applied to the substrate is relieved by the grooves provided around the surface acoustic wave element. Therefore, even after mounting the surface acoustic wave device, it is possible to suppress fluctuations in frequency characteristics (mainly resonance frequency) due to the influence of stress.

  Preferably, the groove is tapered.

  Thereby, even when an electrical wiring passing through the groove is required, the wiring is easily formed.

  Preferably, the substrate further includes an electrical wiring provided on one surface side of the substrate so as to be routed from a predetermined position of the surface acoustic wave element to an outer peripheral side of the groove, and the groove is provided at a position where the electrical wiring should be crossed. Do not provide.

  This eliminates the need to traverse the electrical wiring along the groove when the electrical wiring is routed to the outer peripheral side, thereby making it possible to more reliably avoid problems such as disconnection of the electrical wiring.

  Preferably, the plug is provided through the substrate and electrically connects the electrical wiring and the semiconductor circuit, and is provided in contact with the plug on the other surface side of the substrate. And a connection terminal for establishing electrical connection with the circuit.

  As a result, the semiconductor circuit can be easily connected to an external circuit by a mounting method such as a flip chip bonding method. In addition, since the surface acoustic wave element side is opposite to the mounting surface, it is possible to easily adjust the characteristics of the surface acoustic wave element (for example, repair of comb electrodes) even after the surface acoustic wave device is mounted. There is also.

  The second aspect of the present invention is an electronic device including the surface acoustic wave element according to the first aspect of the present invention. Here, “electronic device” refers to a device in general that realizes a certain function using an electronic circuit or the like, and its configuration is not particularly limited. For example, a personal computer, a PDA (portable information terminal), an electronic device, etc. Various devices such as notebooks are listed.

  Thereby, a high quality electronic device is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic plan view illustrating the structure of a surface acoustic wave device according to an embodiment to which the present invention is applied. 2 is a schematic cross-sectional view in the II-II line direction shown in FIG. 1, and FIG. 3 is a schematic cross-sectional view in the III-III line direction shown in FIG. The surface acoustic wave device 1 according to this embodiment shown in FIGS. 1 to 3 includes a surface acoustic wave element on one side of a substrate 10 and a semiconductor circuit on the other side. Specifically, the surface acoustic wave device 1 includes a substrate 10, an insulating film 12, a piezoelectric film 14, an electrode 16, a groove 18, an electrical wiring 20, a plug 22, a semiconductor circuit 24, and connection terminals (bumps) 26. It is configured.

  The substrate 10 supports each element and is provided with a semiconductor circuit 24 on the other surface side (the lower surface side in the drawing), and is made of a semiconductor substrate such as a silicon substrate, a GaAs substrate, a SiGe substrate, or an SOI substrate.

The insulating film 12 is a thin film made of an insulator such as SiO ₂ , SiN, Al ₂ O ₃ , and is provided on one side of the substrate 10.

  The piezoelectric film 14 is formed on one surface side of the substrate 10 using a piezoelectric material such as zinc oxide as a constituent material. The piezoelectric film 12 may be formed using a material other than zinc oxide as long as it is a constituent material having piezoelectricity. Examples of the constituent material include lithium tantalate, lithium niobate, potassium niobate, crystal, lead zirconate titanate, and the like.

  The electrode 16 is a surface acoustic wave generating electrode having a comb-like planar shape, and is provided on the upper side of the piezoelectric film 14 using a conductive material such as aluminum. In the example shown in FIG. 1, a general one-port resonator is shown as an example of the electrode 16, but other structures (for example, a two-port resonator, a ladder filter, etc.) may be used. A surface acoustic wave element is configured including the electrode 16 and the piezoelectric film 14 existing around the electrode 16.

  The groove 18 is provided on one side of the substrate 10 so as to surround the surface acoustic wave element. The groove 18 is formed using a photolithography technique and an etching technique. For example, in this embodiment, the entire thickness of the substrate 10, the insulating film 12, and the piezoelectric film 14 is about 100 μm, and the depth of the groove 18 is about 50 μm or less. Further, as shown in FIG. 2, in this embodiment, the groove 18 is formed so that the cross-sectional shape thereof is tapered. When the groove 18 is provided only on one side of the substrate 10 as in the present embodiment, there is an advantage that a larger area can be secured on the other side of the substrate 10 for use in forming the semiconductor circuit 24.

  The electrical wiring 20 is provided on one surface side of the substrate 10 so as to be routed from a predetermined position of the surface acoustic wave element (a predetermined position of the electrode 16) to the outer peripheral side of the groove 18. The electrical wiring 20 is for electrically connecting the electrode 16 and the plug 22 and is formed using a conductive material such as aluminum. Further, as shown in FIGS. 1 and 3, in the present embodiment, the groove 18 is not provided at a position where the electric wiring 20 should be crossed. Thereby, the formation surface of the electric wiring 20 becomes flat also in the said position, and it becomes difficult to produce malfunctions, such as a disconnection.

  The plug 22 is provided through the substrate 10 and has a function of electrically connecting the electrical wiring 20 and the semiconductor circuit 24. The plug 22 is formed by providing a through hole in the substrate 10 and filling the through hole with a conductive material such as tungsten.

  The semiconductor circuit 24 is provided near the surface on the other surface side of the substrate 10 made of a semiconductor substrate, and has a function of controlling the operation of the surface acoustic wave element. Although shown in a simplified manner in each figure, the semiconductor circuit 24 actually includes a plurality of transistor elements and other circuit elements (resistors, capacitors, etc.).

  The connection terminal 26 is provided in contact with the plug 22 on the other surface side of the substrate 10 and is used for electrical connection between the semiconductor circuit 24 and an external circuit. For example, the surface acoustic wave device 1 is mounted on the other circuit board or the like via the connection terminals 26 by a flip chip bonding method.

  As described above, according to the present embodiment, the stress applied to the substrate 10 is relieved by the grooves 18 provided around the surface acoustic wave element. Therefore, even after the surface acoustic wave device 1 is mounted, it is possible to suppress fluctuations in frequency characteristics (mainly resonance frequency) due to the influence of stress.

  The surface acoustic wave device according to this embodiment described above can be applied to various electronic devices. Next, an example of an electronic apparatus including the surface acoustic wave element according to this embodiment will be described.

  FIG. 4 is a perspective view illustrating an example of an electronic apparatus including the surface acoustic wave element. FIG. 4 shows a personal computer as an example of an electronic device. A notebook personal computer 100 shown in FIG. 4 includes a main body 102 having a keyboard 101 and a display panel 103. The surface acoustic wave device according to this embodiment is used as a component such as a filter, a resonator, and a reference clock included in the main body 102 of the personal computer 100. The surface acoustic wave device according to the present embodiment can be used for various electronic devices such as a mobile phone, a car navigation device, an electronic notebook, and an electronic game device in addition to the personal computer.

  In addition, this invention is not limited to the content of each embodiment mentioned above, A various deformation | transformation implementation is possible within the scope of the summary of this invention.

  For example, in the above-described embodiment, the case where a comb-shaped electrode is used as an example of an electrode that is a constituent element of a surface acoustic wave element has been described. However, the shape of the electrode is not limited to this, and other shapes ( For example, it may be a circle.

  In the above-described embodiment, the groove 18 is provided only on one side of the substrate 10. However, the groove 18 may be provided on the other side of the substrate 10. It may be provided in both.

  Further, in the above-described embodiment, the groove 18 is not provided at a position where the electric wiring 20 should be crossed. You may make it let. In this case, by forming the groove 18 in a tapered shape as shown in the above-described embodiment, it is easy to form an electrical wiring inside the groove 18.

1 is a schematic plan view illustrating a structure of a surface acoustic wave element according to an embodiment. It is a schematic cross section of the II-II line direction shown in FIG. It is a schematic cross section of the III-III line direction shown in FIG. It is a perspective view which shows an example of an electronic device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Surface acoustic wave device, 10 ... Board | substrate, 12 ... Insulating film, 14 ... Piezoelectric film, 16 ... Electrode, 18 ... Groove, 20 ... Electrical wiring, 22 ... Plug, 24 ... Semiconductor circuit, 26 ... Connection terminal (bump) )

Claims (5)

A surface acoustic wave element provided on one side of the substrate;
A groove provided on at least one side of the substrate so as to surround the surface acoustic wave element;
A semiconductor circuit having a function of controlling the operation of the surface acoustic wave element and provided on the other surface side of the substrate;
A surface acoustic wave device comprising:   The surface acoustic wave device according to claim 1, wherein the groove has a tapered shape.   The circuit board further includes electrical wiring provided on one surface side of the substrate so as to be routed from a predetermined position of the surface acoustic wave element to the outer peripheral side of the groove, and the groove is not provided at a position where the electrical wiring should be traversed. The surface acoustic wave device according to claim 1. A plug provided through the substrate and electrically connecting the electrical wiring and the semiconductor circuit;
Provided in contact with the plug on the other side of the substrate, a connection terminal for electrical connection between the semiconductor circuit and an external circuit,
The surface acoustic wave device according to claim 1, further comprising: An electronic apparatus comprising the surface acoustic wave device according to claim 1.

Images