JP2001345658A - Manufacturing method of surface acoustic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an elastic wave device, which reduces damage to IDT electrodes on an elastic surface wave element when this element is cut and divided with laser beam radiation on a piezoelectric wafer. SOLUTION: The method of manufacturing an elastic wave device comprises a step of forming a piezoelectric wafer, an elastic surface wave element comprising at least one IDT for transmitting or receiving an elastic surface wave and at least one reflector on the piezoelectric wafer, and a dummy electrode along a scribe line between the elastic surface wave element and adjacent elastic surface wave element; a step of inspecting the elastic surface wave element on the piezoelectric wafer, using a wafer probe; and a step of radiating a laser beam from above the dummy electrode between the elastic surface wave elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention secures a laser scribe line for cutting (scribing) adjacent surface acoustic wave elements by laser irradiation,
The present invention relates to a method of manufacturing a surface acoustic wave device for cutting a surface acoustic wave element individually without damaging a DT electrode.

[0002]

2. Description of the Related Art Recently, a surface acoustic wave device used for a mobile communication device such as a cellular phone, which has been rapidly developing, is small, thin, highly reliable, and inexpensive. The surface acoustic wave device itself has been downsized to meet the demand for
They are being made thinner. By the way, a surface acoustic wave device is
A circuit element that performs signal processing by converting an electric signal into a surface wave, and is used for a filter, a resonator, a delay element, and the like. By providing a metal electrode called an IDT (interdigital transducer, comb-shaped electrode, or interdigital electrode) on an elastic substrate (piezoelectric substrate) having a piezoelectric effect, conversion from an electric signal to a surface wave and back conversion are performed. . It is also known that a metal electrode called a reflector is provided on the left and right sides of the IDT to confine surface wave energy between the reflectors to form a low-loss filter.

[0003] In general, the process of manufacturing a surface acoustic wave device is as follows.
A wafer process of forming a plurality of surface acoustic wave element electrodes on a piezoelectric substrate wafer, and dividing the piezoelectric substrate wafer having electrodes formed on the piezoelectric substrate wafer into individual surface acoustic wave element units, It is divided into an assembly process for packaging the wave element. In the wafer process,
A large number of electrodes (SAW electrodes: excitation electrodes and reflectors) of a surface acoustic wave device are simultaneously formed on a 6-inch diameter piezoelectric substrate wafer by photolithography.

Further, the above-described step of dividing the piezoelectric substrate wafer having electrodes formed on the piezoelectric substrate wafer into individual surface acoustic wave element units is performed by diamond cutting (rotating diamond) widely applied to scribing of semiconductor components. A plurality of surface acoustic wave elements on a piezoelectric substrate wafer are divided into individual surface acoustic wave element units and cut off.

[0005]

In order to cope with the recent cost reduction of a mobile communication device or a surface acoustic wave device mounted thereon, a surface acoustic wave element itself on a single piezoelectric substrate wafer is required. It is needless to say that the surface acoustic wave element is efficiently arranged and formed by reducing the size and shape of the surface acoustic wave element more than before, and the surface acoustic wave element is formed with high density on a limited area of the piezoelectric substrate wafer. For the IDT formed on the surface acoustic wave element, the electrode configuration (electrode width, electrode spacing) including the IDT is set to a design value based on a desired pass band characteristic of the surface acoustic wave device by a photolithography technique which is a manufacturing process. Therefore, miniaturization and high-density can be realized by making the electrodes on the surface acoustic wave element as close as possible.

However, in the current manufacturing process, so-called cutting (scribing) for dividing a plurality of surface acoustic wave elements on a piezoelectric substrate wafer into individual surface acoustic wave element units.
As for diamond, the method of diamond cutting (cutting using a rotating diamond disk) is adopted, so the physical thickness of the diamond disk (the thickness of the disk) is improved and the elastic surface formed on the piezoelectric substrate wafer In order to increase the number of wave elements, diamond cutting is no longer suitable.

Therefore, the cutting (scribing) step of dividing the surface acoustic wave element unit is replaced with the conventional diamond cutting, and a laser beam is applied between the surface acoustic wave elements formed on the piezoelectric substrate wafer, and a cutting method using a laser is performed. This greatly improves the division process for each surface acoustic wave element unit, and ensures that even if the surface acoustic wave elements formed on the piezoelectric substrate wafer are densely arranged, they can be cut and divided reliably. became.

However, when a surface acoustic wave element on a piezoelectric substrate wafer is divided by using a laser, a small gap between the surface acoustic wave elements is irradiated with the laser as shown in FIG. There is a problem that an IDT electrode on a surface acoustic wave element is damaged by inducing an action of guiding a laser beam to the electrode side by an electrode such as an IDT formed on the element.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a piezoelectric substrate wafer and at least one IC for transmitting or receiving a surface acoustic wave to or from the piezoelectric substrate wafer.
Forming a dummy electrode along a scribe line between the surface acoustic wave element and a surface acoustic wave element adjacent to the surface acoustic wave element including the DT and at least one reflector; A method of manufacturing a surface acoustic wave device, comprising the steps of: inspecting a surface acoustic wave element with a wafer probe; and irradiating a laser from above the dummy electrode between the surface acoustic wave elements.

In short, in order to prevent damage to the electrodes such as the IDT on the surface acoustic wave element, which is raised by the conventional laser irradiation cutting, an IDT electrode is formed on the piezoelectric substrate wafer and is adjacent to the surface acoustic wave element. By forming a dummy electrode along the scribe line between the surface acoustic wave elements, the laser irradiation for cutting is absorbed by the dummy electrode and used as a guideline for laser irradiation. The present invention realizes no damage to the electrodes of the wave element.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In each drawing, the same reference numeral indicates the same object. FIG. 1 shows a plan view of an embodiment of the present invention. Two pairs of at least one pair of crossed electrodes are provided on the piezoelectric substrate wafer 1, and one set of the crossed electrodes intersects the regular electrode 10 having a uniform crossing length and the other set of crossed electrode fingers. Apotized electrode 12 with varying length
A surface acoustic wave filter in which a shield electrode 11 is disposed between a regular electrode 10 and an apodized electrode 12, and is formed in a continuous state at an end face 13 of the surface acoustic wave element 3;
The end portions 13 are individually divided at the scribe lines 4 (cut portions).

FIG. 2 is a process chart of a method of manufacturing a surface acoustic wave device according to the present invention. As shown in the manufacturing flow of FIG. 2, a piezoelectric substrate wafer 1, a surface acoustic wave element 3 composed of at least one IDT 2 for transmitting or receiving a surface acoustic wave to or from the piezoelectric substrate wafer 1, Forming a dummy electrode 5 along a scribe line 4 between the acoustic wave element 3 and an adjacent surface acoustic wave element 3, and inspecting the surface acoustic wave element 3 on the piezoelectric substrate with a wafer probe;
A surface acoustic wave device is manufactured by a step of irradiating a laser from above the dummy electrode 5 between the surface acoustic wave elements 3.

In short, when the surface acoustic wave element 3 on the piezoelectric substrate wafer 1 is divided into individual surface acoustic wave elements 3 and cut by irradiating a laser, the laser irradiation is applied to the electrodes on the surface acoustic wave element 3. Is formed along the scribe line 4 between the surface acoustic wave element 3 and the adjacent surface acoustic wave element 3 so that the laser irradiation for cutting is absorbed by the dummy electrode 5. It is characterized by the following. The type of laser used here is suitable for general electronic components and there is no limitation, but examples thereof include a YAG laser and a carbon dioxide laser.

FIG. 3 shows a surface acoustic wave element 3 formed by the present invention.
1 shows a perspective view around the dummy electrode 5 and the concept of cutting. When the laser is irradiated from above the surface acoustic wave element 3, the laser is blocked by the dummy electrode 5 formed along the scribe line 4, thereby preventing the electrode forming the surface acoustic wave element 3 from being directly damaged. It is. In FIG. 3, the dummy electrodes 5 are formed on both sides of the scribe lines 4 along the scribe lines 4. However, it goes without saying that the same effect can be obtained even if the dummy electrodes 5 are formed over the scribe lines 4.

[0015]

According to the present invention, damage to electrodes on a surface acoustic wave element during laser cutting for dividing a surface acoustic wave element formed on a piezoelectric substrate wafer is greatly reduced, and a high density By arranging and forming the surface acoustic wave elements on the substrate, a large number of surface acoustic wave elements can be efficiently manufactured, and the yield can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state of the present invention.

FIG. 2 is a process chart of a method of manufacturing a surface acoustic wave device according to the present invention.

FIG. 3 is a perspective view of the periphery of a dummy electrode of the surface acoustic wave device showing the cutting concept of the present invention.

FIG. 4 is a perspective view showing the periphery of a dummy electrode of a surface acoustic wave device showing a conventional cutting concept.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric substrate wafer 2 IDT 3 Surface acoustic wave element 4 Scribe line 5 Dummy electrode

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // B23K 101: 40 H01L 21/78 L

Claims (4)

[Claims] 1. A surface acoustic wave element comprising a piezoelectric substrate wafer, at least one IDT for transmitting or receiving a surface acoustic wave to or from the piezoelectric substrate wafer, and a surface acoustic wave element adjacent to the surface acoustic wave element Forming a dummy electrode along the scribe line between; and inspecting the surface acoustic wave element on the piezoelectric substrate with a wafer probe; and applying a laser from above the dummy electrode between the surface acoustic wave elements. A method for manufacturing a surface acoustic wave device, comprising a step of irradiating. 2. A piezoelectric substrate wafer and at least one I / O for transmitting or receiving a surface acoustic wave to or from the piezoelectric substrate wafer.
Forming a dummy electrode along a scribe line between the surface acoustic wave element and a surface acoustic wave element adjacent to the surface acoustic wave element including the DT and at least one reflector; A method for manufacturing a surface acoustic wave device, comprising: inspecting a surface acoustic wave element with a wafer probe; and irradiating a laser from above the dummy electrode between the surface acoustic wave elements. 3. The method of manufacturing a surface acoustic wave device according to claim 1, wherein the same metal material as that of the IDT is used for a dummy electrode between the surface acoustic wave element and an adjacent surface acoustic wave element. A method for manufacturing a surface acoustic wave device. 4. The method for manufacturing a surface acoustic wave device according to claim 1, wherein said dummy electrode is arranged so as to avoid a scribe line.