JPH0575288B2 - - Google Patents

Description

[Detailed Description of the Invention] <Object of the Invention> [Industrial Field of Application] The present invention provides an etching method for a crystal resonator that reduces misalignment between the upper and lower surfaces of a protective film in the etching process of a rotating Y plate. Regarding.

[Prior Art] FIG. 2 is a cut-out diagram of an AT-cut crystal resonator, which is the most widely used type of crystal resonator.
The XYZ axes indicate the initial axial directions and are obtained by rotating the Y plate by θ° around the X axis. The Z′ axis and Y′ axis are new axial directions. FIG. 3 is a cross-sectional view of this AT-cut crystal resonator after being etched. As shown in the figure, a protective film 11 is applied to the upper and lower surfaces of the plate having a thickness t, respectively, to prevent etching from proceeding to unnecessary portions. The etching rate is fast in the Z-axis direction, just as the growth rate in the Z-axis direction is fast. Therefore, etching progresses in the Z-axis direction of the rotating Y plate, and from the relationship with the cutting angle θ°,
By shifting the distance between one upper end U1 and one lower end D1 of the opposing protective films 11 by t/tanθ, it is possible to obtain a straight etched slope.

The other upper surface end U2 and the other lower surface end D2 of the other opposing protective film 11 are used to determine the width dimension to be extracted by etching processing, and the one upper surface end U1 and the other lower surface end D2 are Bottom end D
They are arranged with a certain width from each other.

Incidentally, as a conventional example, there is a drawing such as FIG. 9b of Japanese Patent Laid-Open No. 57-157616.

[Problems to be Solved by the Invention] In this conventional etching method, the difference in level between the upper surface edge of the etched protective film and the mask edge is large, and the sloped portion of the etched surface becomes long, which deteriorates the characteristics of the crystal resonator. It was a factor that caused the deterioration of the

[Object of the present invention] An object of the present invention is to obtain a crystal resonator in which etching is performed by reducing the step difference between the upper end and the lower end, thereby shortening the slope of the etched surface and preventing deterioration of characteristics. The purpose is to

<Structure of the present invention> [Means for solving the problems] The present invention provides a crystal resonator which is produced by applying protective films to the upper and lower surfaces of a rotating Y plate obtained by rotating the Y plate by θ° around the X axis. In the etching method, the thickness of the rotary Y plate is t, the extension line connecting the upper and lower ends of the protective film is the Z-axis direction, and one upper end of the protective film is U1, the other is U2,
Etching processing of a crystal resonator characterized in that the upper surface end U1 and the lower surface end D2 are shifted by t/tanθ, where one lower surface end is D1 and the other lower surface end is D2. It's a method.

[Operations and Examples] FIG. 1 is a sectional view of a crystal resonator showing an example of the present invention. The crystal resonator is an AT cut crystal resonator cut out in the same way as the conventional example. The rotated Y plate is obtained by rotating the Y plate by θ° around the X axis with a plate thickness of t, and the Z' and Y' axes are new axial directions. As shown in the figure, each crystal resonator is provided with two protective films on its upper surface and two on its lower surface. A protective film is applied to areas where etching is not desired. The extension line connecting one upper surface end U1 and the other lower surface end D2 of the protective film 11 is arranged so that the interval between the protective films on the side that is approximately in the Z-axis direction is shifted by t/tan θ. The other upper surface end U2 and one lower surface end D1 of the other pair of protective films 11 are more suitable than the one upper surface end U1 and the other lower surface end D2 in order to have a width dimension for etching. There is a certain distance between them. In the embodiment, one upper surface end U1
and the other lower surface end U2, and the width dimensions of one lower surface end D1 and the other lower surface end D2 are set to be half the distance between one upper surface end U1 and the other lower surface end D2.

In this way, the etching progresses from both the upper and lower surfaces in the Z-axis direction, penetrating exactly at half the plate thickness t. INDUSTRIAL APPLICATION This invention is utilized when forming the external shape of a crystal resonator, and forming a frame by penetrating a crystal plate with a predetermined width in the thickness direction by etching. That is, compared to the conventional etching surface, the inclined part of the etching surface can be etched by about half the length, and the etching time is shortened. Since the level difference is small, the characteristics of the crystal resonator can also be improved.

In addition, although an example of an AT-cut crystal resonator was shown in the example, thickness-shear resonators such as BT cut
CT cut, DT cut, HT cut, SL cut,
It may be a contour vibrator such as a GT cut, or it may be a so-called rotating Y plate.

Further, the protective film can be formed by depositing a metal electrode, or by using an insulating film or a coating film.

[Effects of the present invention] When etching a rotary Y plate, the present invention etches the upper surface end and the lower surface end on the side where the extension line is approximately the Z axis to t/tanθ. Since the protective film was placed and etched at a different angle, etching progressed efficiently from both sides, and the difference in level between the upper and lower ends could be reduced. Therefore, the characteristics of the crystal resonator are not deteriorated. Additionally, the etching time was reduced by nearly half compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the rotary Y plate of the present invention after being etched. FIG. 2 is a diagram showing the axial relationship of the rotary Y plate used in the present invention, and FIG. 3 is a sectional view of the conventional rotary Y plate when etched. 11...Protective film, U1...One upper surface end, U
2...Another upper surface end, D1...One lower surface end, D2...Another lower surface end.

Claims (1)

[Claims] 1. In a crystal resonator etching method in which a protective film is applied to the upper and lower surfaces of the rotated Y plate obtained by rotating the Y plate by θ° around the X axis, the plate thickness of the rotated Y plate is t. The extension line connecting the upper and lower ends of the protective film is the Z-axis direction, and one upper end of the protective film is U1, the other upper end is U2, one lower end is D1, and the other When the lower surface end is D2, the upper surface end U1 and the lower surface end D2 are t/tanθ
A method for etching a crystal resonator, which comprises arranging the crystal resonator at a different angle and etching it through the crystal resonator.