JPS63200607A - Manufacture of surface acoustic wave device - Google Patents

Abstract

PURPOSE:To improve the yield and to prevent characteristic deterioration due to open conductor wire end short-circuit by coating an organic resin to a face subjected to coarse face processing or slot processing so as to form an organic resin film so as to prevent the mixture of chips of a piezoelectric substrate onto the metallic vapor deposition film. CONSTITUTION:The surface 11a of a piezoelectric substrate 11 made of a material such as LiTaO3 is subjected to mirror polishment and coarse face processing or slot processing is applied to a rear face 11b of the piezoelectric substrate 11. Then an organic resin such as a silicon group is applied to the rear face 11b of the piezoelectric substrate 11 applied with coarse surface processing or slot processing to form an organic resin film 12. After the metallic vapor- deposition film 13 is formed onto the surface 11a of the piezoelectric substrate 11 subjected to mirror surface polishment, the part of the exposed metallic vapor deposited film 13 is etched and many conductor patterns 14 are formed on the piezoelectric substrate 11. Then the piezoelectric substrate 11 formed with many conductor patterns 14 is split into each conductor pattern 14a and the piezoelectric chip substrate 15 split in this way is exfoliated from the organic resin film 12.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a surface acoustic wave device used for, for example, a filter, a resonator, a delay line, or the like.

(Prior Art) Conventionally, as a method for manufacturing surface acoustic wave devices applied to filters, resonators, delay lines, etc., photolithography has been used to form a conductor pattern having comb-shaped electrodes on a piezoelectric substrate. This is generally done using technology.

A conventional method for manufacturing a surface acoustic wave device using such photolithography technology will be explained based on FIG. 2.

As shown in the figure, first, the surface 1a of the rectangular piezoelectric substrate 1 on which the conductive pattern is formed is mirror-polished (FIG. 2-A), and then the back surface 1b of the piezoelectric substrate 1 is roughened. Machining or grooving is performed (Figure 2-B). Next, a metal vapor deposition film 2 is formed on the mirror-polished surface 1a of the piezoelectric substrate 1 (FIG. 2-C), and a resist film (not shown) is further formed thereon. Thereafter, an unexposed portion corresponding to the pattern is formed on the resist film by exposure using a mask (not shown) having a large number of patterns almost identical to the desired conductor pattern, and the exposed portion of the resist film is exposed to light. Dissolve and remove. Then, the metal vapor deposited film 2 exposed by this
, and then remove the unexposed portions of the resist film to form a large number of conductor patterns 3 having comb-like electrodes (not shown) on the piezoelectric substrate 1 (second
Figure-D). After this, this large number of conductor patterns 3 are formed on the surface l.
The piezoelectric substrate 1 formed on a is connected to the individual conductive patterns 3a.
Figure 2-E)
The surface acoustic wave device is taken out and the manufacturing process of the surface acoustic wave device is completed (FIG. 2-F).

(Problem to be Solved by the Invention) However, in such conventional manufacturing methods, fragments of the piezoelectric substrate that are generated as a result of surface roughening or groove processing on the back surface of the piezoelectric substrate are removed during metal film deposition. The problem is that these fragments may get mixed into the film, or even after vapor deposition, they may adhere to the evaporated crotch, causing disconnection or short circuits in the comb-like electrodes of surface acoustic wave devices and other harmful electrode fingers. There was a point.

The present invention is intended to solve these problems, and prevents pieces of the piezoelectric substrate generated by surface roughening or groove processing on the back side of the piezoelectric substrate from being mixed into the metal deposited film, and prevents disconnection of conductor wiring, It is an object of the present invention to provide a method for manufacturing a surface acoustic wave device that can prevent characteristic deterioration due to short circuits and the like and improve yield, thereby manufacturing a highly reliable surface acoustic wave device.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention includes a step of mirror-polishing one surface of a piezoelectric substrate, and a step of mirror-polishing the other surface of the piezoelectric substrate that has been mirror-polished. a step of roughening or grooving a surface; a step of applying an organic resin to the surface with the roughening or grooving to form an organic resin film; and a mirror-polished piezoelectric substrate. A step in which a metal vapor deposited film and a resist film are sequentially formed on one surface of the conductor, and exposed using a mask having a plurality of patterns approximately equal to the desired conductor pattern to dissolve and remove the resist film corresponding to the exposed portion; A step of removing the metal vapor deposited film corresponding to the resist film portion by etching to form a plurality of conductor patterns and removing the remaining resist film, and a step of removing the piezoelectric substrate on which the plurality of conductor patterns are formed into individual conductor patterns. The method is characterized by comprising a step of cutting the piezoelectric substrate into individual conductor patterns, and a step of peeling off the piezoelectric substrate cut into individual conductor patterns from the organic resin film.

(Function) In the method for manufacturing a surface acoustic wave device of the present invention, since an organic resin is applied to the surface that has been roughened or grooved to form an organic resin film, the back surface of the piezoelectric substrate can be roughened. Alternatively, it is possible to prevent pieces of the piezoelectric substrate generated by groove processing from getting into the metal evaporated film, prevent property deterioration due to conductor wiring disconnections, short circuits, etc., and improve yields, thereby producing highly reliable surface acoustic wave devices. be able to manufacture.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing the manufacturing process of a surface acoustic wave device according to an embodiment of the present invention.

As shown in the figure, in the manufacturing method of this embodiment, first, the surface 11a of the rectangular piezoelectric substrate 11 made of, for example, LiTaO3 is mirror polished.
), and further surface roughening or groove processing is performed on the back surface 11b of this piezoelectric substrate 11 (FIG. 1-B). Thereafter, an organic resin, such as a silicon-based resin, is applied to the back surface 11b of the piezoelectric substrate 11, which has been roughened or grooved, to form an organic resin film 12 (FIG. 1--). Next, a metal evaporated film 13 made of, for example, AJ2 is formed on the surface 11a of the mirror-polished piezoelectric substrate 11 (FIG. 1-D), and a positive resist is applied thereon to form a resist wA (FIG. 1-D). (not shown). Thereafter, an unexposed portion corresponding to the pattern is formed on the resist film by exposure using a mask (not shown) having a large number of patterns almost identical to the desired conductor pattern, and this is removed using a developer. Dissolve and remove.

Then, the exposed portion of the metal vapor deposited film 13 is etched using an etching solution such as a mixed solution of acetic acid, nitric acid, and phosphoric acid, and then the unexposed portion of the resist film is exposed and a developer is used. Then, a large number of conductive patterns 14 having comb-like electrodes (not shown) are formed on the piezoelectric substrate 11 (FIG. 1-E). After that, the piezoelectric substrate 11 on which a large number of conductor patterns 14 are formed is cut into pieces into individual conductor patterns 14a.
), the piezoelectric chip substrate 15 thus divided and cut is peeled off from the organic resin film 12 described above (FIG. 1-G). Then, this peeled-off piezoelectric chip substrate 15 is fixed to a stem (not shown), and the manufacturing process of the surface acoustic wave device is completed through a bonding and ink connection process and a hermetic process.

According to the method for manufacturing a surface acoustic wave device of this embodiment, after roughening or semi-processing is performed on the back surface 11b of the piezoelectric substrate 11, an organic resin is applied to the back surface 11b to form an organic resin film 12. Therefore, it is possible to prevent fragments of the piezoelectric substrate 11 generated from the back surface 11b of the piezoelectric substrate 11 from invading and adhering to the metal vapor deposited film 13, thereby preventing property deterioration due to disconnection or short circuit of conductor wiring, and improving yield. It becomes possible to aim for.

Furthermore, FIGS. 3 and 4 show the effects of the method of manufacturing the surface acoustic wave device of this embodiment.

FIG. 3 is a diagram showing the frequency of occurrence of electrode defects in the surface acoustic wave device manufactured by the M method of this embodiment and the surface acoustic wave device manufactured by the conventional manufacturing method. As shown in this figure, in surface acoustic wave devices manufactured using conventional manufacturing methods, electrode defects of 10 or more force points frequently occur in one device, but with the manufacturing method of this example, None of the manufactured surface acoustic wave devices had electrode defects in more than 10 locations, and most of them were concentrated in devices with electrode defects in 1 to 5 locations. From this, it can be seen that the number of electrode defects in the piezoelectric substrate 11 can be reduced by the manufacturing method of this embodiment.

Further, FIG. 4 is a diagram showing the effect of the manufacturing method of this embodiment from the relationship between the center frequency (horizontal axis) of the surface acoustic wave device and the average value of the number of electrode defects (vertical axis).

In the same figure, in the conventional surface acoustic wave device shown by the solid line, as the center frequency increases, the width of the conductor wiring increases, so the average number of electrode defects also tends to increase. This tendency becomes noticeable from a center frequency of 50 MHz or above, but by manufacturing using the method of this example, the number of electrode defects can be effectively reduced as shown by the dotted line in the figure. .

[Effects of the Invention] According to the method for manufacturing a surface acoustic wave device of the present invention, it is possible to prevent pieces of the piezoelectric substrate, etc., generated by surface roughening or groove processing on the back surface of the piezoelectric substrate from being mixed into the metal vapor deposited film. It becomes possible to manufacture highly reliable surface acoustic wave devices by preventing property deterioration due to conductor wiring breaks, short circuits, etc. and improving yield.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of each process for explaining the manufacturing method of a surface acoustic wave device according to an embodiment of the present invention, and FIG. 2 is a sectional view of each process for explaining the manufacturing method of a conventional surface acoustic wave device. FIG. 3 is a diagram for detailed explanation of the present invention,
FIG. 4 is a diagram for explaining the effect in terms of the relationship with the center frequency. 11... Piezoelectric substrate 12... Organic resin film 13... Metal vapor deposited film

Claims (1)

[Claims] (1) A step of mirror-polishing one surface of the piezoelectric substrate, a step of performing surface roughening or groove processing on the other surface of the mirror-polished piezoelectric substrate, and this surface roughening or groove processing. a step of applying an organic resin to the applied surface to form an organic resin film; and a step of sequentially forming a metal vapor deposition film and a resist film on one surface of the mirror-polished piezoelectric substrate in a pattern substantially equal to the desired conductor pattern. A step of dissolving and removing the resist film corresponding to the exposed portion by exposing using a mask having a plurality of resist films, and removing the metal vapor deposited film corresponding to the portion of the resist film that has been dissolved and removed by etching to form a plurality of conductor patterns. a step of removing the remaining resist film; a step of cutting the piezoelectric substrate on which a plurality of conductor patterns are formed into individual conductor patterns; and a step of cutting the piezoelectric substrate into individual conductor patterns into A method for manufacturing a surface acoustic wave device, comprising the step of peeling off a resin film.