JP4514571B2 - Surface acoustic wave device, method of manufacturing the same, and communication device - Google Patents

Description

  The present invention relates to a surface acoustic wave device, a manufacturing method thereof, and a communication device. More specifically, it is a surface acoustic wave device having a face-down mounting structure used as a surface acoustic wave filter, and in particular, a surface acoustic wave device having improved out-of-passband attenuation, a manufacturing method thereof, and the surface acoustic wave device. The present invention relates to a communication device.

  In recent years, surface acoustic wave filters that can be miniaturized and non-adjusted have come to be used in various communication devices, and are used as band-pass filters, etc., as communication devices increase in frequency and functionality. There is an increasing demand for increasing the out-of-band attenuation of the surface acoustic wave filter. For example, as a 900 MHz band cellular phone filter, it is desired to improve the out-of-band attenuation in the vicinity of the pass band, and the high-performance high-attenuation filter that also improves the out-of-band attenuation in a high frequency band of several GHz. Is desired.

  FIG. 9 shows a schematic sectional view of a mounting structure in a conventional surface acoustic wave (hereinafter abbreviated as SAW) apparatus. In the surface acoustic wave device shown in FIG. 9, 51 is a piezoelectric substrate, 52 is a ground pad, 53 is an IDT (Inter Digital Transducer) electrode (excitation electrode) of an interdigital transducer formed on the piezoelectric substrate 51 for SAW elements, 54 Is a conductive pattern formed on the package 57, and 55 is a bump for connection. In the configuration shown in the figure, the ground pad 52 and the IDT electrode 53 are formed of, for example, an Al—Cu film, and the conductive pattern 54 and the ground pad 52 are electrically connected by a bump 55 made of, for example, Au. Further, the lid 56 is sealed from above the package 57 via the bonding layer 58 by seam welding or the like, and the airtightness inside the surface acoustic wave element is maintained.

The main causes of the deterioration of the out-of-band attenuation level in such a conventional surface-down surface acoustic wave device are, for example, electrodes such as the ground pad 52 of the surface acoustic wave element, the IDT electrode 53, and the conductive pattern 54 of the package 57. Electromagnetic coupling between input and output due to increase in electrical resistance, parasitic inductance and stray capacitance. In particular, a filter region having an input pad portion such as a ground pad 52 and an output pad portion together with an IDT electrode 53 is formed on one main surface of the piezoelectric substrate 51, and a conductor layer (not shown) is formed on the other main surface. In the case of a surface acoustic wave device having a structure in which a surface acoustic wave element is mounted face-down, a conductor layer is formed on the other main surface of the piezoelectric substrate 51 in a region facing the input pad portion and output pad portion of the filter region. Therefore, there is a problem that capacitive coupling occurs between the input pad portion and the output pad portion, thereby deteriorating the out-of-band attenuation.
JP-A-4-313906

  A surface acoustic wave element is an element using comb-like excitation electrodes (IDT electrodes) fabricated on a piezoelectric substrate. Usually, since a piezoelectric body exhibits pyroelectricity due to a rapid temperature change, when a device having an excitation electrode on a piezoelectric substrate is manufactured, a process with a rapid temperature change is performed due to the pyroelectricity of the piezoelectric substrate. Sparks are generated between the electrodes, and the element is destroyed. Therefore, in order to prevent electric charges from being accumulated in the piezoelectric substrate as much as possible, it is common to form a conductor layer over the entire back surface of the piezoelectric substrate. However, this backside conductor layer is effective in preventing pyroelectric breakdown during the device fabrication process, but is disadvantageous for improving out-of-band attenuation due to the configuration of the device itself for the reasons described above (for example, (See Patent Document 1).

  In addition, a surface acoustic wave element having a face-up mounting structure in which an excitation electrode, an input pad portion, and an output pad portion are formed on the surface (one main surface) of the piezoelectric substrate and a conductor layer is formed on the back surface (the other main surface). In the case of a structure in which the back side is placed on the top surface of the package and grounded, capacitive coupling between the input pad part on the front side and the output pad part through the conductor layer on the back side is not a problem, In the case of face-down mounting, since the back surface is not grounded, capacitive coupling between the input pad portion and the output pad portion through the conductor layer on the back surface becomes a problem, and the out-of-band attenuation of the filter by the surface acoustic wave element is reduced. There is a problem that it is difficult to secure enough.

  Accordingly, an object of the present invention is to provide a surface acoustic wave device that can improve the out-of-band attenuation of a filter and has excellent reliability in a surface acoustic wave device having a face-down mounting structure of surface acoustic wave elements. It is to provide a used communication device.

  The surface acoustic wave device of the present invention is a surface acoustic wave device in which a filter region including an excitation electrode, an input pad portion, and an output pad portion is formed on one main surface of a piezoelectric substrate, and a conductor layer is formed on the other main surface. Are mounted on the mounting substrate with the one main surface facing each other, and the conductor layer is formed by separating a region facing at least one of the input pad portion and the output pad portion from another region. It is characterized by being.

  Further, the surface acoustic wave device of the present invention is an elastic surface in which a filter region including an excitation electrode, an input pad portion, and an output pad portion is formed on one main surface of a piezoelectric substrate, and a conductor layer is formed on the other main surface. The wave element is mounted on the mounting substrate with the one main surface facing, and the conductor layer includes a portion connected from the input pad portion to the excitation electrode in a direct current and the output pad portion. A region facing at least one of the portions connected to the excitation electrode in a direct current manner is formed separately from the other regions.

  In the surface acoustic wave device according to the present invention, in each of the above configurations, the surface roughness of the other main surface of the portion where the conductor layer is removed for separation is a region where the conductor layer is formed. It is larger than the surface roughness of the other main surface.

  In the surface acoustic wave device according to the present invention, in each of the above configurations, an annular conductor is formed on the one main surface of the piezoelectric substrate so as to surround the filter region, and the annular conductor corresponds to the mounting substrate. It is characterized by being bonded to the base-side annular conductor formed in this way.

  The surface acoustic wave device according to the present invention is characterized in that, in the above configuration, the excitation electrode is electrically connected to the annular conductor through a resistor, and the annular conductor is set to a ground potential. To do.

  In the surface acoustic wave device according to the present invention, in each of the above structures, the piezoelectric substrate has a lithium tantalate single crystal, a lithium niobate single crystal, or a lithium tetraborate single crystal having an oxygen content less than the stoichiometric composition. It is characterized by comprising crystals.

  In the surface acoustic wave device according to the present invention, in each of the above-described configurations, the piezoelectric substrate may be configured such that the one principal surface side is made of a piezoelectric material and the other principal surface side is made of a material having a relative dielectric constant smaller than that of the piezoelectric material. It is a feature.

  A communication device of the present invention is characterized by including at least one of a reception circuit and a transmission circuit having any one of the surface acoustic wave devices of the present invention.

  A first method of manufacturing a surface acoustic wave device according to the present invention includes a step of forming a conductor layer on one main surface of a piezoelectric substrate, and patterning the conductor layer on the one main surface to output an excitation electrode, an input pad portion, and an output A step of forming a plurality of surface acoustic wave element regions having a filter region having a pad portion, a step of forming a conductor layer on the other main surface of the piezoelectric substrate, and Separating each element region to obtain a large number of surface acoustic wave elements, and then mounting the surface acoustic wave element on a mounting substrate with the one main surface facing, A step of forming a conductor layer on one principal surface of the piezoelectric substrate, a step of forming a plurality of surface acoustic wave element regions, a step of forming a conductor layer on the other principal surface of the piezoelectric substrate, and the plurality of surface acoustic waves. During the process of obtaining the element, Comprises, after the mounting step, a step of separating a region facing at least one of the input pad portion and the output pad portion of the conductor layer formed on the other main surface from another region. To do.

  According to a first method of manufacturing a surface acoustic wave device of the present invention, in the above configuration, a region facing at least one of the input pad portion and the output pad portion of the conductor layer formed on the other main surface is removed. In place of the step of, facing at least one of a portion of the conductor layer that is DC connected from the input pad portion to the excitation electrode and a portion of the conductor pad that is DC connected from the output pad portion to the excitation electrode The area to be separated is separated from other areas.

  The second manufacturing method of the surface acoustic wave device of the present invention includes a step of forming a conductor layer on one principal surface of the piezoelectric substrate, and patterning the conductor layer on the one principal surface to thereby form an excitation electrode and an input pad portion. Forming a plurality of surface acoustic wave element regions each having a filter region comprising an output pad portion, a step of forming a conductor layer on the other main surface of the piezoelectric substrate, and then the elasticity of the piezoelectric substrate. Mounting the surface wave element region on the mounting substrate with the one principal surface facing each other, and then separating the piezoelectric substrate and the mounting substrate for each surface acoustic wave element region. And a step of forming a conductor layer on one main surface of the piezoelectric substrate, a step of forming a plurality of surface acoustic wave element regions, a step of forming a conductor layer on the other main surface of the piezoelectric substrate, and the mounting step. During or After the mounting step, the method includes a step of separating a region facing at least one of the input pad portion and the output pad portion of the conductor layer formed on the other main surface from another region. Is.

  According to a second method of manufacturing a surface acoustic wave device of the present invention, in the above configuration, a region facing the at least one of the input pad portion and the output pad portion of the conductor layer formed on the other main surface is different. Instead of the step of separating from the region, a portion of the conductor layer that is connected in a direct current from the input pad portion to the excitation electrode and a portion that is connected in a direct current from the output pad portion to the excitation electrode The method includes a step of separating a region facing at least one from another region.

  Further, in the first and second manufacturing methods of the surface acoustic wave device of the present invention, in each of the above configurations, the conductor layer formed on the other main surface is removed when partially removed for separation. It is characterized in that the surface roughness of the other main surface of the region where the surface roughness of the other main surface of the part is not removed is made larger.

  According to the surface acoustic wave device of the present invention, the conductor layer formed on the other principal surface of the piezoelectric substrate is formed such that a region facing at least one of the input pad portion and the output pad portion is separated from other regions. As a result, the parasitic capacitance formed between the input pad portion and the output pad portion of the filter can be separated between the input / output pad portions. Since the amount of coupling due to the parasitic capacitance between the input and output pad portions can be greatly reduced compared to the case where it is formed, deterioration of the attenuation characteristic outside the passband due to the parasitic capacitance can be suppressed. The amount of external attenuation can be improved.

  Further, according to the surface acoustic wave device of the present invention, the conductor layer formed on the other main surface of the piezoelectric substrate is connected to the DC pad from the input pad portion to the excitation electrode and from the output pad portion to the excitation electrode. When the region facing at least one of the DC-connected portions is formed separately from the other regions, the DC-connected portion from the input pad portion to the excitation electrode and the output pad portion Since the coupling amount between the input and output pad parts due to the parasitic capacitance formed by the portion connected to the excitation electrode from the DC to the excitation electrode can be reduced, the attenuation characteristic outside the passband due to the parasitic capacitance is reduced. Therefore, the passband attenuation can be further improved.

  According to the surface acoustic wave device of the present invention, in each of the above configurations, the surface roughness of the other main surface of the portion where the conductor layer of the other main surface of the piezoelectric substrate is removed for separation is such that the conductor layer is If the surface roughness of the other main surface of the formed region is larger than the surface roughness of the out-of-pass band attenuation characteristic, it is possible to reduce the amount of deterioration due to the propagation of the bulk wave. The out-of-band attenuation characteristic can be further greatly improved. The attenuation outside the passband is deteriorated due to the capacitive coupling between the input and output pads, and the acoustic wave that is not converted into the surface acoustic wave by the excitation electrode of the resonator and becomes a bulk wave is generated by the piezoelectric substrate. It also deteriorates by propagating through the inside, being reflected by the surface of the other main surface of the piezoelectric substrate and the end surface of the surface acoustic wave element, and again being coupled to the excitation electrode of the resonator formed in the filter region. Although the deterioration due to the propagation of the bulk wave is small compared to the influence due to the parasitic capacitance, it is preferable to suppress the deterioration due to the bulk wave in order to completely satisfy the strict requirement required for the attenuation characteristic outside the passband. On the other hand, the surface roughness of the other main surface of the portion where the conductor layer of the other main surface of the piezoelectric substrate is removed for separation is greater than the surface roughness of the other main surface of the region where the conductor layer is formed. Since the bulk wave is scattered on the other main surface of the partially roughened piezoelectric substrate by making it large, the bulk wave generated from the excitation electrode in the filter region is excited again by the excitation electrode formed in the filter region. Therefore, the out-of-passband attenuation characteristic can be further improved.

  Further, according to the surface acoustic wave device of the present invention, the annular conductor is formed on one main surface of the piezoelectric substrate so as to surround the filter region, and the annular conductor is formed correspondingly on the mounting substrate. When bonded to the annular conductor, the surface acoustic wave element is firmly mounted on the mounting substrate by bonding the annular conductor and the substrate-side annular conductor, and the excitation electrode, the input pad portion, and the output pad portion are hermetically sealed. Since the surface acoustic wave element is mounted on the mounting substrate as will be described later, when the conductor layer on the other main surface of the piezoelectric substrate is processed, Processing can be performed without damaging the excitation electrode formed on the main surface.

  Further, according to the surface acoustic wave device of the present invention, when the excitation electrode is electrically connected to the annular conductor via the resistor, and the annular conductor is at the ground potential, the excitation electrode is a direct current. Although it is connected to ground potential, it can be isolated from the ground potential in the frequency band where the surface acoustic wave device is used, so it does not affect the band-pass characteristics of the filter. In addition, it is possible to prevent electric charges from being accumulated in the excitation electrode. Accordingly, pyroelectric breakdown of the surface acoustic wave device can be reliably prevented even when the conductor layer is not provided on the entire other main surface of the piezoelectric substrate.

  According to the surface acoustic wave device of the present invention, the piezoelectric substrate is made of a lithium tantalate single crystal, a lithium niobate single crystal, or a lithium tetraborate single crystal having an oxygen content less than the stoichiometric composition. The piezoelectric substrate, like the resistor that electrically connects the excitation electrode to the annular conductor, appears to be a conductor in terms of direct current but appears to be an insulator in the frequency band in which the surface acoustic wave device is used. Has properties. Therefore, by using this as the substrate of the surface acoustic wave device, it is possible to prevent charges from being accumulated on the excitation electrode without affecting the bandpass characteristics of the filter. Therefore, the pyroelectric breakdown of the surface acoustic wave device can be more reliably prevented even if there is no conductor layer on the entire other main surface of the piezoelectric substrate. In addition, the number of processes is not increased in the manufacturing process of the surface acoustic wave device in order to prevent pyroelectric breakdown.

  In the surface acoustic wave device of the present invention described above, the capacitance between the input and output pad portions of the filter is reduced by forming a predetermined region of the conductor layer on the other main surface of the piezoelectric substrate separately from the other regions. However, this corresponds to reducing the area of the electrode forming the parasitic capacitance. However, the piezoelectric substrate has one principal surface side made of a piezoelectric material, and the other principal surface side has a relative dielectric constant higher than that of the piezoelectric material. When made of a small material, the effective dielectric constant between the input pad portion and the output pad portion of the filter can be reduced, and this can also reduce the parasitic capacitance (this forms a parasitic capacitance). This corresponds to reducing the dielectric constant between the electrodes.) Therefore, the attenuation characteristic outside the passband can be further improved. In particular, when this piezoelectric material is a lithium tantalate single crystal, a lithium niobate single crystal or a lithium tetraborate single crystal whose oxygen content is less than the stoichiometric composition, the effect of preventing pyroelectric breakdown well And the effect of reducing the effective dielectric constant can be obtained.

  According to the communication device of the present invention, by using the surface acoustic wave device of the present invention as described above for at least one of the reception circuit and the transmission circuit of the communication device, severe out-of-band attenuation conventionally required. As a surface acoustic wave device having a good out-of-pass attenuation characteristic, it is small in size, so that it can take a larger mounting area for other components, Since the range of selection widens, a highly functional communication device can be realized.

  In order to produce the surface acoustic wave device of the present invention as described above, the following method for producing the surface acoustic wave device of the present invention is suitable.

  According to the first method of manufacturing a surface acoustic wave device of the present invention, the step of forming a conductor layer on one principal surface of a piezoelectric substrate and the patterning of the conductor layer on the one principal surface to respectively form an excitation electrode and an input pad portion Forming a plurality of surface acoustic wave element regions each having a filter region comprising an output pad portion, forming a conductor layer on the other main surface of the piezoelectric substrate, and obtaining the plurality of surface acoustic wave elements. When a region facing at least one of the input pad portion and the output pad portion of the conductor layer on the other main surface is separated from other regions, a plurality of surface acoustic wave elements are integrally formed. Since the process for the conductor layer on the other main surface can be performed collectively on the piezoelectric substrate, the efficiency is improved. In the case where a predetermined region of the conductor layer on the other main surface of the piezoelectric substrate is partially separated after the surface acoustic wave element is mounted on the mounting substrate with the one main surface facing the temperature, It is possible to reliably prevent pyroelectric breakdown of the surface acoustic wave element that may occur due to the history.

  According to the second manufacturing method of the surface acoustic wave device of the present invention, the step of forming the conductor layer on the one principal surface of the piezoelectric substrate and the patterning of the conductor layer on the one principal surface for the excitation electrode, the input pad portion, and the output pad Forming a plurality of surface acoustic wave element regions having a filter region having a portion, forming a conductor layer on the other main surface of the piezoelectric substrate, and forming the surface acoustic wave element region of the piezoelectric substrate on the mounting substrate. When the conductor layer on the other main surface is partially separated during the mounting process with the main surfaces facing each other, the other surface of the piezoelectric substrate integrally formed with a plurality of surface acoustic wave elements Since the process for the conductor layer on the main surface can be performed at once, the efficiency in the removal process is improved. In addition, when partially separating a predetermined region of the conductor layer on the other main surface of the piezoelectric substrate after the step of mounting the surface acoustic wave element region of the piezoelectric substrate with the one main surface facing the mounting substrate, It is possible to reliably prevent pyroelectric breakdown of the surface acoustic wave element that may occur due to a temperature history applied in the mounting process. Furthermore, since the process for the conductor layer on the other main surface can be performed in a state where the piezoelectric substrate on which a large number of surface acoustic wave element regions are fabricated is mounted on the mounting substrate, the efficiency in the separation process is improved. Of course, the separation process for the conductor layer on the other main surface may be performed after the step of separating the piezoelectric substrate and the mounting substrate for each surface acoustic wave element region. In the step of separating each surface acoustic wave element region, either the piezoelectric substrate or the mounting substrate may be separated first, or the piezoelectric substrate and the mounting substrate may be separated at the same time.

  By the way, the deterioration of the attenuation outside the passband due to the propagation of the bulk wave can be suppressed by using a piezoelectric substrate whose surface has been greatly roughened. However, while the excitation electrode that propagates the surface acoustic wave is formed, Since the surface needs to be a mirror surface, there is a problem in that the piezoelectric substrate with only the other main surface largely rough is warped greatly due to temperature change and is easily damaged during the manufacturing process of the surface acoustic wave element. On the other hand, the thickness of piezoelectric substrates for surface acoustic wave elements has been gradually reduced due to the recent demand for smaller and lower height electronic components. However, the probability of breakage increases as the thickness of piezoelectric substrates decreases. End up.

  On the other hand, according to the method for manufacturing a surface acoustic wave device of the present invention, when separating a predetermined region of the conductor layer formed on the other principal surface of the piezoelectric substrate, the other principal surface of the region from which the conductor layer is removed is separated. When the surface roughness is made larger than the surface roughness of the other main surface of the region where the conductor layer is formed, the bulk of the piezoelectric substrate that is being thinned is increased without increasing the risk of damage. It is possible to efficiently suppress deterioration of the attenuation characteristic outside the passband due to wave propagation. In addition, this is efficient because it can be performed simultaneously with countermeasures against deterioration of the attenuation characteristic outside the passband due to parasitic capacitance.

  As described above, according to the present invention, even when the mounting (flip chip mounting) is performed with the excitation electrode forming surface of the piezoelectric substrate facing the main surface of the mounting substrate, the input pad portion and the output pad portion of the filter Is not capacitively coupled through the conductor layer on the other main surface, so that the attenuation outside the passband is not deteriorated even though the surface acoustic wave device is small. In addition, pyroelectric breakdown of the surface acoustic wave element can be prevented even if there is no conductor layer on the entire other main surface of the piezoelectric substrate in the manufacturing process. Also, due to recent demands for miniaturization and low profile of parts, surface acoustic wave devices are also required to reduce the thickness of the piezoelectric substrate, but the electrodes on one main surface and the other main surface of the piezoelectric substrate are required. The capacitance between the conductive layer and the surface conductor layer increases, and therefore the deterioration of the attenuation outside the passband caused by the coupling of the parasitic capacitance between the input and output pad portions of the filter becomes more serious. By partially separating the conductor layer on the surface, it is possible to obtain a surface acoustic wave device that is thin and has good passband attenuation characteristics.

  Since the surface acoustic wave device of the present invention has a good out-of-pass band attenuation characteristic and is small in size, the receiving circuit having the surface acoustic wave device of the present invention and the surface acoustic wave device of the present invention According to the communication device of the present invention including at least one of the transmission circuits having high performance by realizing a large mounting area of other components while utilizing the good filter characteristics of the surface acoustic wave device of the present invention. A communication device that can be manufactured is manufactured.

  Hereinafter, an example of an embodiment of a surface acoustic wave device and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings. In the drawings described below, the same portions are denoted by the same reference numerals. Further, the size of each electrode, the distance between the electrodes, the number of electrode fingers, the interval, and the like are schematically illustrated for explanation, and are not limited to these.

<Example 1 of embodiment>
FIG. 4 is a top view showing one main surface of the surface acoustic wave element in Example 1 of the embodiment of the surface acoustic wave device of the present invention. A top view of the other main surface of the surface acoustic wave element in Example 1 is shown in FIG.

  As shown in FIG. 4, a filter region 9 is formed on the piezoelectric substrate 2 of the surface acoustic wave element 1. In the filter region 9, a plurality of excitation electrodes 3 constituting a resonator, a connection electrode 4 connecting them, and an excitation electrode 3 for connecting the surface acoustic wave element 1 and a mounting substrate (not shown) are connected. An electrically connected input pad portion 5 and an output pad portion 6 are formed.

  The annular conductor 7 is connected to the substrate-side annular conductor of the mounting substrate using solder or the like, functions as a ground electrode of the surface acoustic wave filter, and seals the space between the piezoelectric substrate 2 and the mounting substrate. Have a role. Reference numeral 8 denotes a ground electrode pad.

  Further, as shown in FIG. 1, a conductor layer 10 is formed on the other main surface of the piezoelectric substrate 2. Here, as shown in FIG. 1, the conductor layer 10 has a region 5 a facing the input pad portion 5 of the filter region 9 on one main surface of the piezoelectric substrate 2 and its periphery, and an output pad portion of the filter region 9. 6 and the surrounding area are separated from other regions, the input pad portion 5 of the filter region 9 and the output pad portion 6 of the filter region 9 are located between the conductor layers 10. Capacitive coupling can be prevented through the generated parasitic capacitance, and therefore the attenuation outside the passband can be greatly improved. In FIG. 1, 9 a indicates a region facing the filter region 9.

  In this example, both the region 5a facing the input pad portion 5 of the filter region 9 on the other main surface of the piezoelectric substrate 2 and the periphery thereof, and the region 6a facing the output pad portion 6 and the periphery thereof are both conductor layers 10. Although the pattern separated from the other regions is shown, if at least one of these regions 5a and 6a is separated from the other regions of the conductor layer 10, a certain amount of attenuation outside the passband is achieved. The effect of improvement is obtained.

  In this example, the annular conductor 7 is used as the ground electrode of the surface acoustic wave filter, but the ground conductor of the surface acoustic wave filter may be directly connected to the ground electrode of the mounting substrate without using the annular conductor 7 as the ground electrode. I do not care.

<Example 2 of embodiment>
FIG. 2 is a top view showing the other main surface of the surface acoustic wave element in Example 2 of the embodiment of the surface acoustic wave device of the invention. In this example, the configuration on the one main surface side of the piezoelectric substrate 2 is the same as in Example 1, but the pattern of the conductor layer 10 on the other main surface is different. In Example 1, the conductor layer 10 includes only the region 5a facing the input pad portion 5 of the filter region 9 on the other main surface of the piezoelectric substrate 2 and the periphery thereof, and the region 6a facing the output pad portion 6 of the filter region 9 and the periphery thereof. The pattern separated from the other regions was used, but in this example 2, the portion connected from the input pad portion 5 of the region filter 9 on one main surface of the piezoelectric substrate 2 to the excitation electrode 3 of the resonator was connected in a direct current manner. And at least one region of the region 5b facing the region 5b and the region 6b facing the portion connected to the resonator from the output pad portion 6 of the filter region 9 to the excitation electrode 3 of the resonator is separated from the other regions to form a conductor layer. 10 is formed. Thus, by separating the region 5b and the region 6b from other regions and forming the conductor layer 10, the parasitic capacitance can be further reduced, and capacitive coupling via the parasitic capacitance can be more reliably suppressed. Can do.

  Further, the pattern of the conductor layer 10 is connected in a direct current manner from the input pad portion 5 of the filter region 9 on one main surface of the piezoelectric substrate 2 to the excitation electrode 3 of the resonator, as shown in the same top view in FIG. The region 5c facing the entire portion and the region 6c facing the entire portion of the filter region 9 that is DC-connected from the output pad portion 6 of the filter region 9 to the excitation electrode 3 of the resonator are separated from other regions. It may be a simple pattern.

<Example 3 of embodiment>
FIG. 5 is a top view showing one main surface of the surface acoustic wave element in Example 3 of the embodiment of the surface acoustic wave device of the invention. In this example, the configuration on the other main surface side of the piezoelectric substrate 2 is the same as the example shown in FIG. 3, and all the excitation electrodes 3 are in direct current conduction with the annular conductor 7 on the one main surface side of the piezoelectric substrate 2. The excitation electrode 3 forming the resonator and the annular conductor 7 were connected via a resistor 11. Further, the annular electrode 7 is connected to the substrate-side annular conductor of the mounting substrate so as to have a ground potential. As described above, the excitation electrode 3 is electrically connected to the annular conductor 7 via the resistor 11, and the annular conductor 7 is set to the ground potential. Therefore, it is possible to effectively prevent the pyroelectric breakdown of the surface acoustic wave element 1.

  The resistor 11 is selected to have a sufficiently high resistance in the frequency band in which the filter is used and a resistance value that looks almost like an insulator. As the material of the resistor 11, a high resistance semiconductor such as silicon or titanium oxide is preferably used. These materials can control the resistance value to an appropriate value by adding a trace amount of an element such as boron or adjusting the composition ratio.

<Example 4 of embodiment>
In this example, as a configuration for preventing pyroelectric breakdown more simply, the piezoelectric substrate 2 includes a lithium tantalate single crystal, a lithium niobate single crystal, or a lithium tetraborate single crystal having an oxygen content lower than the stoichiometric composition. Crystals were used. Similar to the resistor 11 described above, these materials have the property that even though they look like conductors in terms of direct current, they have a sufficiently high resistance in the frequency band in which the filter is used and look almost like insulators. Therefore, by using these materials for the piezoelectric substrate 2, it is possible to prevent electric charges from accumulating on the excitation electrode 3 without affecting the bandpass characteristics of the filter, so that the entire surface of the other main surface of the piezoelectric substrate 2 can be prevented. Even without the conductor layer 10, pyroelectric breakdown of the surface acoustic wave element 1 can be satisfactorily prevented. Moreover, it is advantageous in that the number of steps is not increased in the manufacturing process of the surface acoustic wave device in order to prevent pyroelectric breakdown.

<Example 5 of embodiment>
In this example, the effective dielectric constant between each electrode (excitation electrode 3, connection electrode 4, input pad portion 5, output pad portion 6) on one main surface of the piezoelectric substrate 2 and the conductor layer 10 on the other main surface is reduced. By doing so, the parasitic capacitance was reduced. Specifically, the piezoelectric substrate 2 is made of a piezoelectric material such as a lithium tantalate single crystal or a lithium niobate single crystal on one main surface side, and a material having a lower relative dielectric constant on the other main surface side than the piezoelectric material on the one main surface. It can be realized while ensuring the necessary piezoelectric characteristics.

  As this piezoelectric material, various piezoelectric materials used for surface acoustic wave elements may be used. In particular, lithium tantalate single crystal or lithium niobate single crystal whose oxygen content is less than the stoichiometric composition. Alternatively, when lithium tetraborate single crystal is used, it is possible to obtain both the effect of preventing pyroelectric breakdown well and the effect of reducing the effective dielectric constant. Further, quartz, silicon, silicon carbide, glass or the like can be used as the dielectric material having a small relative dielectric constant. The piezoelectric substrate 2 made of such two kinds of materials can be obtained by laminating a substrate made of these piezoelectric materials and a substrate made of a dielectric material.

  The surface acoustic wave device of the present invention can be applied to a communication device. That is, the surface acoustic wave device of the present invention is used as a band-pass filter included in these circuits in a communication device including at least one of a receiving circuit and a transmitting circuit. For example, the transmission signal output from the transmission circuit is put on the carrier frequency by the mixer, the unnecessary signal is attenuated by the band pass filter, and then the transmission signal is amplified by the power amplifier and transmitted from the antenna through the duplexer. A communication device equipped with a transmission circuit that can perform reception, receives the received signal with an antenna, passes through a duplexer, amplifies the received signal with a low noise amplifier, attenuates unnecessary signals with a band-pass filter, and then uses a carrier frequency with a mixer Can be applied to a communication device including a receiving circuit that separates a signal from the signal and transmits the signal to a receiving circuit that extracts the signal. The surface acoustic wave device of the present invention is employed in at least one of the receiving circuit and the transmitting circuit. Thus, an excellent communication device of the present invention with improved transmission characteristics can be provided.

  Next, an example of an embodiment of a method for manufacturing a surface acoustic wave device according to the present invention will be described according to steps.

<Example 6 of embodiment>
FIGS. 6A to 6J are cross-sectional views for each process showing an example of an embodiment of the first manufacturing method of the surface acoustic wave device of the present invention.

  First, as shown in FIG. 6A, (1) a conductor layer is formed on one main surface of the piezoelectric substrate, and as shown in FIG. 6B, (2) a conductor layer on one main surface of the piezoelectric substrate. Are formed to form a plurality of surface acoustic wave element regions each having a filter region having an excitation electrode, an input pad portion, and an output pad portion, as shown in FIG. A conductor layer is formed on the other main surface. The steps so far may be performed in the order of (1), (3), (2) or (3), (1), (2) other than the above order.

  Here, as the piezoelectric substrate, a lithium tantalate single crystal, a lithium niobate single crystal, a lithium tetraborate single crystal, or the like can be used.

  On the other hand, the conductor layer on the main surface is made of aluminum, aluminum alloy, copper, copper alloy, gold, gold alloy, tantalum, tantalum alloy, or a laminated film of these materials, and these materials and titanium, chromium, etc. A laminated film with a layer made of the above material can be used. As a method for forming the conductor layer, a sputtering method or an electron beam evaporation method can be used.

  As a method for patterning the conductor layer, there is a method in which photolithography is performed after forming the conductor layer, and then RIE (Reactive Ion Etching) or wet etching is performed. Alternatively, a resist is formed on one main surface of the piezoelectric substrate before the conductor layer is formed and photolithography is performed to open a desired pattern, and then a conductor layer is formed, and then the resist is formed on an unnecessary portion. A lift-off process for removing the entire conductor layer may be performed.

  Moreover, aluminum etc. can be used as a material of the conductor layer of the other main surface of the piezoelectric substrate. As the film formation method, a sputtering method or an electron beam evaporation method can be used.

  Next, as shown in FIG. 6D, a protective film for protecting the excitation electrode is formed. Silicon, silica or the like can be used as the material for the protective film. As a film forming method, a sputtering method, a CVD (Chemical Vapor Deposition) method, an electron beam evaporation method, or the like can be used. In this protective film forming process, a temperature of about 50 to 300 ° C. may be necessary to obtain good film quality and adhesion. In such a case, the conductor layer on the other main surface is subjected to pyroelectric breakdown. Works effectively in prevention.

  Next, as shown in FIG. 6E, (4) a new conductor layer is laminated on the input pad portion and the output pad portion to form the input pad and the output pad. This new conductor layer has a structure for electrically and / or structurally connecting the surface acoustic wave element and the mounting substrate with high reliability. For example, if solder is used for connection, the solder is wet. In the case of using gold bumps for connection, it has a function of adjusting the hardness of the pad so that gold can be bonded using ultrasonic waves or the like. As a material and structure of such a new conductor layer, a laminated film of chromium / nickel / gold or chromium / silver / gold, or a thick film of gold or aluminum can be used. As a film forming method, a sputtering method or an electron beam evaporation method can be used. In addition, in order to obtain good film quality and adhesion even in this new conductor layer film forming step, a temperature of about 50 to 300 ° C. may be necessary, but even in such a case, the conductor layer on the other main surface is It functions effectively to prevent pyroelectric breakdown.

  The pattern of the excitation electrode, the input pad portion, the output pad portion, etc. on the one principal surface of the piezoelectric substrate manufactured through the steps up to here is the same as that shown in FIG. However, the protective film is not shown in FIG.

  Next, when the fabrication is performed by the so-called multi-cavity method in which a large number of surface acoustic wave element regions are formed on one piezoelectric substrate so far, as shown in FIG. The piezoelectric substrate is separated for each surface acoustic wave element region to obtain a large number of surface acoustic wave elements. As a separation method, for example, a dicing method using a dicing blade, a laser cutting method by laser processing, or the like can be used.

  Next, as shown in FIG. 6 (h), (6) the surface acoustic wave element is mounted on the mounting substrate with one main surface facing. Here, as shown in FIG. 6 (f), between the steps (1) to (3) and the step (5) of obtaining a large number of surface acoustic wave elements, or the step (6) of mounting. Thereafter, a region facing at least one of the input pad portion and the output pad portion of the filter region of the conductor layer formed on the other main surface of the piezoelectric substrate is separated from the other regions.

  As a method of separating this conductor layer from other regions, before the step (5), after protecting one main surface of the piezoelectric substrate with a resist or the like, a resist is formed on the other main surface of the piezoelectric substrate and photo Lithography is performed and a necessary portion of the resist is opened, and then the conductive layer in the opening is removed by wet etching, RIE (Reactive Ion Etching), sandblasting, or the like. At this time, if a method of etching and removing the conductor layer mainly by a chemical action is used, the conductor layer on the other main surface can be removed with certainty without damaging the piezoelectric substrate. Also, if a method of grinding and removing the conductor layer mainly by physical action is used, the conductor layer can be removed and at the same time the other main surface of the piezoelectric substrate in that portion can be made rougher than the original state. , Propagating through the inside of the piezoelectric substrate from one filter region, reflected by the other main surface of the piezoelectric substrate, and coupled to the excitation electrode formed in the other filter region, and deteriorated the attenuation characteristic outside the passband Bulk waves can be scattered at this portion of the other principal surface of the piezoelectric substrate, and the out-of-passband attenuation characteristics can be further improved.

  Thereafter, the resist on one main surface side and the resist on the other main surface side of the piezoelectric substrate are removed.

  In these steps, since each process can be performed on the piezoelectric substrate on which a plurality of surface acoustic wave elements are formed, the plurality of surface acoustic wave elements can be processed in a batch, which is efficient.

  Further, in the case where the predetermined region of the conductor layer is separated from the other regions after the step (6), since the one main surface of the piezoelectric substrate is already arranged to face the mounting substrate, The step of protecting can be omitted. In particular, when sealing is performed using an annular conductor, the surface acoustic wave element is firmly fixed to the mounting substrate, and the filter region is shielded from the outside air. By using a method such as etching, RIE (Reactive Ion Etching), sand blasting or the like, the conductor layer of the other main surface to be processed can be efficiently removed. Further, the conductor layer on the other main surface may be removed by grinding and polishing using a router or sandpaper.

  In this example, as shown in FIG. 6 (i), (7) the surface acoustic wave element mounted on the mounting substrate is resin-molded using a sealing resin, and then shown in FIG. 6 (j). (8) The mounting substrate is divided for each surface acoustic wave element together with the mold resin by dicing or the like to obtain the surface acoustic wave device of the present invention.

  In this example, the region facing the input pad portion of the filter region and the output pad portion of the filter region of the conductor layer formed on the other main surface of the piezoelectric substrate is separated from the other regions. This may be done for both areas or for both areas. Further, at least one of a portion of the conductor layer on the other main surface that is DC connected from the input pad portion of the filter region to the excitation electrode and a portion of the filter region that is DC connected from the output pad portion of the filter region to the excitation electrode The region opposite to may be separated from other regions. Furthermore, the region facing the filter region on the other main surface of the piezoelectric substrate may be separated from other regions.

<Example 7 of embodiment>
In Example 6 of the embodiment, after undergoing the step of obtaining a large number of surface acoustic wave elements by separating the piezoelectric substrate on which a large number of surface acoustic wave elements are formed in the step (5) for each surface acoustic wave element region. In this example, as shown in FIG. 7A to FIG. 7J with sectional views similar to FIG. 6A to FIG. In the step shown in FIG. 7 (g), mounting is carried out with one main surface of the piezoelectric substrate having a large number of surface acoustic wave element regions formed on the mounting substrate facing each other before separation for each surface acoustic wave element region. (This step is referred to as (7).) Then, as shown in FIG. 7 (h), the piezoelectric substrate integrated with the mounting base is divided into surface acoustic wave element regions by so-called half dicing, As shown in FIG. 7 (i), the surface acoustic wave element mounted on the mounting substrate is resin-molded using a sealing resin. And de, then separating the base for mounting with the molding resin for each surface acoustic wave element (for this step (8).) And may be. In the case of this example 7, the other main piezoelectric substrate is interposed between the steps (1) to (3) and the step (7) or after the step (7) as shown in FIG. A region facing at least one of the input pad portion and the output pad portion of the filter region formed on the surface is separated from other regions. This separation method and its region are the same as described above.

First, Ti / Al-1 mass% Cu / Ti / Al-1 is formed on one main surface of a piezoelectric substrate 2 (substrate thickness is 250 μm) made of a 38.7 ° Y-cut X-propagating lithium tantalate single crystal substrate from the substrate side by sputtering. Four conductor layers made of mass% Cu were formed. The film thicknesses are 6 nm / 209 nm / 6 nm / 209 nm, respectively. Next, this conductor layer is patterned by photolithography and RIE to form filter regions each including the excitation electrode 3, the input pad portion 5, and the output pad portion 6, and a plurality of surface acoustic wave element regions are formed. did. A mixed gas of BCl ₃ and Cl ₂ was used as an etching gas at this time. The line width of the comb-like electrode forming the excitation electrode 3 and the distance between adjacent comb-like electrodes are both about 1 μm.

  Next, a conductor layer 10 made of pure Al was formed on the other main surface of the piezoelectric substrate 2 by sputtering. The conductor layer 10 has a thickness of 200 nm.

  Next, a new conductor layer made of Cr / Ni / Au was laminated on the input pad portion 5 and the output pad portion 6 to form an input pad and an output pad. The thicknesses of the new conductor layers are 6 nm / 1000 nm / 100 nm, respectively.

  Next, one main surface of the piezoelectric substrate 2 is protected with a photoresist, and then the other main surface is coated with a photoresist and subjected to photolithography, and then subjected to piezoelectric etching by wet etching using a mixed acid of nitric acid, phosphoric acid, and acetic acid. The conductor layer 10 on the other main surface of the substrate 2 was patterned as shown in FIG.

  Next, after removing the photoresist, the piezoelectric substrate 2 was separated by dicing for each surface acoustic wave element region to obtain a large number of surface acoustic wave elements 1.

  Next, the surface acoustic wave element 1 was mounted on a mounting base made of a LTCC (Low Temperature Co-fired Ceramics) substrate with one main surface facing each other. Here, the LTCC substrate has a base-side annular conductor corresponding to the annular conductor 7 formed on one main surface of the piezoelectric substrate 2 and pad electrodes connected to the input / output pads of the surface acoustic wave element 1. Solder was printed on the base-side annular conductor and the pad electrode. When the surface acoustic wave element 1 is mounted thereon, the surface acoustic wave element 1 is disposed so as to coincide with these solder patterns, temporarily fixed by applying ultrasonic waves, and then heated to melt the solder. By doing so, the annular conductor 7 and the base-side annular conductor were connected, and the input / output pad and the pad electrode were connected. As a result, the filter region 9 of the surface acoustic wave element 1 is completely hermetically sealed by the base-side annular conductor of the LTCC substrate and the annular conductor 7 connected thereto. The mounting process of the surface acoustic wave element 1 was performed in a nitrogen atmosphere.

  Next, a resin mold is performed, the other main surface (back surface) of the surface acoustic wave element 1 is protected with a mold resin, and finally the mounting substrate is diced between the surface acoustic wave elements, whereby the elastic surface of the present invention is obtained. A wave device was obtained.

  As a comparative example, a surface acoustic wave in which a filter region including an excitation electrode, an input pad portion, and an output pad portion is formed on one main surface of a piezoelectric substrate as in the prior art, and a conductor layer is formed on the entire other main surface. A surface acoustic wave device was fabricated in which the element was mounted on the mounting substrate with one main surface facing. The top view of this comparative example is the same as FIG.

  About the Example and comparative example of this invention which were produced in this way, the frequency characteristic is shown with a diagram in FIG. In the diagram of FIG. 8, the horizontal axis represents frequency (unit: MHz), the vertical axis represents attenuation (unit: dB), and the characteristic curve indicated by a broken line has a conductor layer formed on the entire other main surface of the LT substrate. The result of the comparative example is shown, and the characteristic curve of the solid line shows the result of the example in which the conductor layer on the other main surface of the LT substrate is separated from the other regions in the region facing the input pad portion and the output pad portion of the filter region. ing. As can be seen from the results shown in FIG. 8, the surface acoustic wave device of the present invention of this example has a very good out-of-passband attenuation as compared with the comparative example. In particular, the amount of attenuation outside the pass band in the vicinity of the pass band is greatly improved as compared with the comparative example.

  Further, when the conductor layer 10 was patterned as shown in FIGS. 2 and 3 and the frequency characteristics were evaluated in the same manner as in the example, the attenuation outside the pass band in the vicinity of the pass band was greatly increased. It was confirmed that it was improved.

  In addition, this invention is not limited to the example of the above embodiment, A various change may be added in the range which does not deviate from the summary of this invention. For example, two or more filter regions may be provided on the same piezoelectric substrate. In that case, the area occupied by the whole can be reduced compared with the case where a plurality of surface acoustic wave elements are separately manufactured.

  4 and the like show the case where a ladder type filter is used, the present invention does not limit the structure of the filter, and a DMS type or an IDT type filter may be used. Further, the arrangement of the input / output terminals is not limited to that shown in FIG. 4 or the like, and may be located on the diagonal of the piezoelectric substrate.

  Further, the material of the excitation electrode is not limited to the materials mentioned in the embodiments, and a single layer of Al, Au, Ta, W, Mo, Ti, Cu or an alloy thereof may be used, or between these and the piezoelectric substrate. Alternatively, a structure in which an adhesion layer is inserted may be used.

  Furthermore, in the above example, the conductor layer is once formed on the other main surface of the piezoelectric substrate, and then the conductor layer around the desired region is removed to separate it from other regions. It is also possible to previously set a region where no film is formed and separate a desired region from other regions of the conductor layer by forming a conductor layer in other regions.

It is a top view which shows the other main surface (pattern of a conductor layer) of the piezoelectric substrate of the surface acoustic wave element in Example 1 of Embodiment of the surface acoustic wave apparatus of this invention. It is a top view which shows the other main surface (pattern of a conductor layer) of the piezoelectric substrate of the surface acoustic wave element in Example 2 of Embodiment of the surface acoustic wave apparatus of this invention. It is a top view which shows the other main surface (pattern of a conductor layer) of the piezoelectric substrate of the surface acoustic wave element in Example 2 of Embodiment of the surface acoustic wave apparatus of this invention. It is a top view which shows one main surface of the piezoelectric substrate of the surface acoustic wave element showing an example of the surface acoustic wave apparatus of this invention. It is a top view which shows one main surface of the piezoelectric substrate of the surface acoustic wave element showing an example of the surface acoustic wave apparatus of this invention. (A)-(j) is sectional drawing for every process which shows an example of embodiment of the 1st manufacturing method of the surface acoustic wave apparatus of this invention, respectively. (A)-(j) is sectional drawing for every process which shows an example of embodiment of the 2nd manufacturing method of the surface acoustic wave apparatus of this invention, respectively. It is a diagram which shows the bandpass characteristic of the surface acoustic wave apparatus produced in the Example of this invention. It is sectional drawing which shows the mounting structure of the conventional surface acoustic wave apparatus typically.

Explanation of symbols

1: Surface acoustic wave element 2: Piezoelectric substrate 3: Excitation electrode 4: Connection electrode 5: Input pad portion 6: Output pad portion 7: Ring conductor 8: Ground electrode pad 9: Filter region
10: Conductor layer
11: Resistor 5a: Region facing the input pad portion 5b, 5c: Region facing the DC-connected portion from the input pad portion to the excitation electrode 6a: Region facing the output pad portion 6b, 6c: Region 9a facing the portion connected to the excitation electrode from the output pad portion in direct current 9a: Region facing the filter region

Claims (13)

A surface acoustic wave device in which a filter region having an excitation electrode, an input pad portion, and an output pad portion is formed on one main surface of a piezoelectric substrate and a conductor layer is formed on the other main surface is formed on the mounting substrate. The surface acoustic wave is mounted with the main surfaces facing each other, and the conductor layer is formed by separating only a region facing the input pad portion and the output pad portion from other regions. apparatus. A surface acoustic wave device in which a filter region having an excitation electrode, an input pad portion, and an output pad portion is formed on one main surface of a piezoelectric substrate and a conductor layer is formed on the other main surface is formed on the mounting substrate. The conductor layers are mounted facing each other, and the conductor layer is connected in a direct current from the input pad portion to the excitation electrode and from the output pad portion to the excitation electrode. a surface acoustic wave device, characterized in that only the region facing the part amount is formed is separated from other regions. The surface roughness of the other principal surface of the portion where the conductor layer is removed for separation is larger than the surface roughness of the other principal surface of the region where the conductor layer is formed. The surface acoustic wave device according to claim 1 or 2. An annular conductor is formed on the one main surface of the piezoelectric substrate so as to surround the filter region, and the annular conductor is joined to a substrate-side annular conductor formed correspondingly on the mounting substrate. The surface acoustic wave device according to any one of claims 1 to 3, wherein the surface acoustic wave device is provided. 5. The surface acoustic wave device according to claim 4, wherein the excitation electrode is electrically connected to the annular conductor via a resistor, and the annular conductor is set to a ground potential. The piezoelectric substrate, surface acoustic wave device according to any one of claims 1 to 5, characterized in that it consists of tantalum single crystal of lithium or lithium niobate single crystal or lithium tetraborate single crystal. 7. The piezoelectric substrate according to claim 1, wherein the one main surface side is made of a piezoelectric material, and the other main surface side is made of a material having a relative dielectric constant smaller than that of the piezoelectric material. Surface acoustic wave device. A communication device comprising at least one of a reception circuit and a transmission circuit, comprising the surface acoustic wave device according to claim 1. Forming a conductor layer on one main surface of the piezoelectric substrate;
Patterning the conductor layer on the one main surface to form a plurality of surface acoustic wave element regions having a filter region comprising an excitation electrode, an input pad portion, and an output pad portion;
Forming a conductor layer on the other main surface of the piezoelectric substrate;
Next, separating the piezoelectric substrate for each surface acoustic wave element region to obtain a plurality of surface acoustic wave elements;
Next, the surface acoustic wave element is mounted on the mounting substrate with the one main surface facing, and
A step of forming a conductor layer on one principal surface of the piezoelectric substrate, a step of forming a plurality of surface acoustic wave element regions, a step of forming a conductor layer on the other principal surface of the piezoelectric substrate, and the plurality of surface acoustic waves. A step of separating only a region facing the input pad portion and the output pad portion of the conductor layer formed on the other main surface between the step of obtaining an element or after the mounting step, from the other region. A method of manufacturing a surface acoustic wave device, comprising: Instead of the step of removing only the region facing the input pad portion and the output pad portion of the conductor layer formed on the other main surface, a direct connection is made from the input pad portion of the conductor layer to the excitation electrode. has been the part and the output pad unit are of the surface acoustic wave device according to claim 9, wherein the separating only the other region region facing the part fractions are galvanically connected to the excitation electrode Production method. Forming a conductor layer on one main surface of the piezoelectric substrate;
Patterning the conductor layer on the one main surface to form a plurality of surface acoustic wave element regions having a filter region comprising an excitation electrode, an input pad portion, and an output pad portion;
Forming a conductor layer on the other main surface of the piezoelectric substrate;
Next, the step of mounting the surface acoustic wave element region of the piezoelectric substrate on the mounting substrate with the one main surface facing,
Next, the step of separating the piezoelectric substrate and the mounting substrate for each surface acoustic wave element region,
Between the step of forming a conductor layer on one main surface of the piezoelectric substrate, the step of forming the multiple surface acoustic wave element regions, the step of forming a conductor layer on the other main surface of the piezoelectric substrate, and the mounting step Or after the mounting step, the method further comprises a step of separating only the region facing the input pad portion and the output pad portion of the conductor layer formed on the other main surface from the other region. A method for manufacturing a surface acoustic wave device. Instead of the step of separating only the region facing the input pad portion and the output pad portion of the conductor layer formed on the other main surface from the other region, from the input pad portion of the conductor layer to the excitation electrode claims, characterized in that it comprises the step of separating the galvanically the attached portion and the output galvanically connected to opposite the part content and region only other areas from the pad portion to the excitation electrode 11. A method for producing a surface acoustic wave device according to 11. When the conductor layer formed on the other main surface is partially removed for separation, the surface roughness of the other main surface in a region where the surface roughness of the other main surface of the portion to be removed is not removed is larger. 13. The method for manufacturing a surface acoustic wave device according to claim 9, wherein the surface acoustic wave device is manufactured.

Images