JP2702918B2 - Manufacturing method of surface acoustic wave device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a surface acoustic wave device, and in particular, each element of a surface acoustic wave device in which a plurality of surface acoustic wave devices are combined is mounted on a substrate. The present invention relates to a method for manufacturing a surface acoustic wave device to which a capacitance measuring method suitable for testing each element in an arrayed state is applied. [Prior Art] The present inventors have previously realized a new surface acoustic wave device having a structure in which a plurality of single-aperture resonators are connected in series. In this device, a combination of resonators constitutes a band-restriction filter with low power consumption. Also, The Acoustical Society of Japan 3-3-8 (5/1975)
As described in Japanese Patent Application Laid-Open No. H08-157, a one-band resonator and a capacitance are ladder-connected to form a bandpass filter. [Problems to be Solved by the Invention] The above-mentioned conventional surface acoustic wave device does not consider the element inspection, and has a problem in the element selection method at the time of mass production. The element inspection in question here is a non-defective judgment in the substrate state performed at the end of the photolithography step of the element formation process, and aims at improving the yield in the subsequent processes, particularly in the assembly step. In general, since a surface acoustic wave filter is capacitive, element inspection is performed by measuring capacitance between input and output terminals of the filter. If the electrode finger of the transducer that excites the surface wave is short-circuited, the capacitance approaches infinity, and it can be determined that a defect has occurred. However, in the case of a device in which a large number of elements are connected in series, the capacitance of each element is about 10 to 20 (pF). ~ 2 (pF). For this reason, the influence on the capacitance value due to the short circuit of one element is almost the same as the measurement error, and there is a disadvantage that the element inspection accuracy is poor. An object of the present invention is to provide a method for manufacturing a surface acoustic wave device which enables simple and accurate element inspection. [Means for Solving the Problems] In the case of one surface acoustic wave element, the element can be accurately inspected by the capacitance measuring method. It is possible by measuring one by one. However, this method is not suitable for mass production, and it is desirable that the inspection be completed by one measurement. Therefore, the object of the present invention is achieved by extracting a capacitance measuring electrode from an intermediate connection terminal that is electrically floating when viewed from the input / output end side, and externally configuring each element in parallel so as to be in parallel. The two terminals when all the elements are connected in parallel become the measurement common terminals. Note that the common terminal used in the present means is removed at the time of use as an element. The removal of the common terminal without changing the conventional process is possible by utilizing the cut grooves of the dicing blade in the substrate cutting process to separate the individual terminals. That is, the common terminal may be extended to the central portion between the elements. [Operation] When the common terminal in the means of the present invention is used as a capacitance measuring terminal, if any one of the plurality of elements is short-circuited, the corresponding equivalent capacitance approaches infinity, and a clear difference occurs in the measured value. . Thus, the present measurement method is an inspection method capable of accurately determining a non-defective element by a single measurement. Also, since the capacitance measuring terminals are removed in the substrate cutting process,
There is no effect on device characteristics. Embodiment An embodiment of the present invention will be described below with reference to FIG. The figure shows a band-restriction filter in which a plurality of pairs of interdigitated electrodes form a transducer and a single aperture resonator is connected in series in a plurality of stages. In the figure, 1 is a piezoelectric substrate, 2 and 3 are input / output terminals, 4-1 to 4 are single aperture resonators, and 5-1 to 6 are resonator connection terminals. For such device inspection of a device composed of a plurality of resonators, extraction electrodes 6 and 7 for capacitance measurement which are means of the present invention are provided, and common terminals 8 and 9 are used as capacitance measurement terminals. I have. FIG. 2 shows an equivalent circuit when each resonator is represented by capacitance. Both terminals of all the resonators are connected to the common terminals 8 and 9, respectively, and are connected in parallel. Therefore, even if any of the resonators is short-circuited, the capacitance value greatly changes, and element inspection can be easily performed. FIG. 3 shows an example in which the above-mentioned means is implemented on an electrode pattern of a surface acoustic wave device. The figure shows a part of a surface acoustic wave device two-dimensionally arranged on a piezoelectric substrate. Input terminal
2. The output terminal 3 is a pad for wire bonding when mounted on a package. It is necessary to provide a pad for bringing together the lead-out electrodes from the resonator connection terminals 5-1 to 6 to contact the short hand of the meter for measuring the capacitance between the common terminals. In the structure of this drawing, the same is true even if the input / output terminal is shared, and the pad can be omitted.
The cutting lines 11-1 to 11-3 are the edges of the chip after cutting the substrate in the chipping step. At the time of this cutting, a kerf 12 is formed, but it is usually about 100 μm with a commercial dicing blade. By this kerf, the central part between the elements,
That is, the extraction electrode provided on the dicing line can be removed simultaneously with the cutting allowance. As a result, the resonators are electrically opened, and a predetermined element characteristic can be obtained in a normal process. The width of the extraction electrode is suitably 3 to 10 μm, and the space width between the two electrodes 6 and 7 is only required to be several μm. Therefore, the width occupied by both electrodes is about 1/5 as compared with the kerf, and the misalignment of the dicing blade is ± 30%.
If it is less than μm, it is sufficient. This is an area where there is no problem in terms of the positioning accuracy of a commercially available cutter. In the above embodiment, the case where the sum of the number of the single aperture resonators is an odd number is described. However, when the sum of the number of the resonators is an even number, one of the input / output end pads used as a capacitance measuring terminal is used. Cannot be used. FIG. 4 shows an embodiment in which an even number of resonators are used, and a capacitance measuring pad 13 is separately provided. FIG. 5 shows an embodiment in the case of a single-pass resonator having a reflector of a surface acoustic wave by a striped electrode or a grating and a bandpass filter having a ladder-shaped capacitance, and FIG. It is shown in FIG. The one-aperture resonator is a combination of the transducer units 16-1 to 16-3 for exciting a surface wave and the reflectors 17-1 to 17-3, and the equivalent circuits 20-1 to 3 represent overall characteristics. In this embodiment, a pad 18-having a necessary and sufficient area to obtain a predetermined capacitance on the piezoelectric substrate is provided.
1 to 3 are provided. For the capacitance, a lead may be drawn out from the pad by a wire, and the capacitance may be connected externally. In this case, as in the above embodiment, the inspection can be performed by alternately extracting the extraction electrodes from each stage and measuring the capacitance between the common measurement terminals 19-1 and 19-2. The relationship between the resonator and the capacitance of the other example of the ladder type is opposite to that of the present embodiment. When the resonators are connected in parallel via the capacitance, one of the resonators is at the ground potential. The electrodes may be drawn out from the terminals on the capacitance side of all the resonators and used as common terminals. The same is true for a combination of an inductance and a resonator. FIG. 7 shows an embodiment in which an intermediate electrode exists in one transducer. An interdigital electrode connected to the input terminal 21 and the output terminal 22, and an electrically floating intermediate electrode 23
It consists of. When element inspection is performed between input and output terminals,
When the intermediate electrode is short-circuited to only one of the input / output terminals, it is difficult to determine a defect. Also in this case, the capacitance measuring terminals 24-1 to 24-2 are connected by the extraction electrode which is the means of the present invention.
Is provided, the element inspection can be easily performed.
The opening of each electrode in the chipping step after the measurement is the same as in the above embodiment. The present invention is not limited to the above-described embodiment, but is effective in element inspection of a surface acoustic wave element having electrically floating terminals. [Effects of the Invention] In the element inspection at the production site, primary screening of non-defective products and defective products is performed at a stage prior to the chipping process, and the defective products are marked to improve the yield in the assembly process. Therefore, according to the method of the present invention, the element inspection in the substrate state becomes accurate and simple, and there is an effect of improving the yield in mass production.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a band rejection filter according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of FIG. 1, and FIGS. FIG. 5 is a diagram showing a configuration of a bandpass filter according to an embodiment of the present invention, FIG. 6 is an equivalent circuit diagram of FIG. 5, and FIG. 7 is an embodiment of the present invention. FIG. 4 is a configuration diagram of a transducer having an intermediate electrode according to an example. 1 ... piezoelectric substrate, 2 ... input terminal, 3 ... output terminal,
4 ... Transducer, 5 ... Resonator connection terminal, 6,
7 ... Electrode, 8,9 ... Capacitance measuring terminal, 10 ... Equivalent capacitance, 11 ... Cutting line, 12 ... Cutting groove, 13 ... Capacitance measuring pad, 17 ... Reflector, 18 ... … Pad for capacitance, 20…
... Equivalent circuit of one aperture resonator, 23 ... Intermediate electrode.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Mitsutaka Hikita               1-280 Higashi Koigabo, Kokubunji-shi               Central Research Laboratory, Hitachi, Ltd. (72) Inventor Yoichi Saigo               Hitachi Bidet, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi               O Engineering Co., Ltd. (72) Inventor Kazuhito Kurosawa               1410 Inada, Katsuta, Hitachi Hitachi, Ltd.               Inside the factory Tokai factory                (56) References JP-A-58-1316 (JP, A)                 JP-A-62-204607 (JP, A)                 Shokai Sho 62-10520 (JP, U)

Claims (1)

(57) [Claims] The method for manufacturing a surface acoustic wave device, wherein n (n ≧ 2) single-aperture resonators provided on a piezoelectric substrate are connected in series between an input terminal and an output terminal by n + 1 connection terminals, A first step of forming a first electrode pattern connected to an odd-numbered connection terminal as viewed from the terminal and a second electrode pattern connected to an even-numbered connection terminal as viewed from the input terminal; A second step of measuring the capacitance between the first electrode pattern and the second electrode pattern; and the first electrode pattern and the first electrode pattern so as to open the connection between the connection terminals in the first step. And a third step of removing at least a part of the second electrode pattern. 2. In the first step, the first electrode pattern may be formed on one side and the second electrode pattern may be formed on the other side with a line segment connecting the input terminal and the output terminal interposed therebetween. 2. The method for manufacturing a surface acoustic wave device according to claim 1, wherein