JPH0382210A - Method of adding weight to crystal resonator - Google Patents

Abstract

PURPOSE:To improve the accuracy of a position with a weight added thereto by adopting the dry method for the addition of the weight, and limiting the range of the addition according to a resist pattern having the plasma resistant characteristic by the photolithography. CONSTITUTION:A metallic film 15 is formed with sputtering on the surface of a protection film comprising a photo resist 13 with high plasma resistance performance while a crystal wafer 10, an electrode film 11 and the resist 13 are laminated. Then the metallic film 15 is lifted off together with the photo resist 13 to leave the metallic film only in the center 15 in figure. Thus, the metallic film 15 as the added weight formed in such a ray is uniform and placed with high accuracy. Thus, the accuracy of the position for adding a weight is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for adding heavy objects to crystal resonators used in microcomputers, information devices such as cordless telephones, communication devices, watches, and the like.

[Summary of the invention]

An object of the present invention is to improve the accuracy of adjusting frequency and frequency-temperature characteristics by limiting the range of a heavy object added for frequency adjustment in a crystal resonator and uniformly depositing it.

[Conventional technology]

FIG. 1 shows a perspective view of the shape of a tuning fork type crystal resonator. In FIG. 1, 1 and 2 are vibrating parts. Numerals 3 and 4 are frequency adjustment sections, which are made of metal such as Au to add weight. Conventionally, this metal such as Au was attached by wet plating.

For this reason, a negative resist was used to protect the parts other than the attachment surface 3.4.

Further, FIG. 2 shows a perspective view of the shape of the GT-cut crystal resonator. In FIG. 2, reference numeral 5.6 indicates a support portion, and this portion is glued to the pedestal. 7 is a vibrating section. Also, 8
．． Reference numeral 9 denotes a frequency adjustment section and a temperature characteristic adjustment section, and weight is added to this section to adjust the above two characteristics. In the case of the GT Kaft crystal resonator, the adjusting section 8.9 is connected to the vibrating section 7.
The position of must be determined with high precision. Conventional 89
Weight was added to the area by vapor deposition of Ag, and other areas were protected by a non-contact metal mask.

In the above method, in the case of a tuning fork type crystal resonator, the frequency variation due to the variation in the added weight within one or 10 pieces, and in the case of a GT cut crystal resonator, the frequency and The problem was the variation in the amount of change in temperature characteristics.

[Problem to be solved by the invention]

An object of the present invention is to make it possible to add weight by sputtering and to make the added weight uniform, thereby suppressing variations in frequency and further improving the positional accuracy of weight addition.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a method for adding a heavy object to the frequency adjustment section of a crystal resonator formed by photolithography, in which the addition of the heavy object is performed by a dry method such as sputtering or vapor deposition, and By limiting the range of weight addition using a photolithographic resist pattern having plasma resistance, the positional accuracy of weight addition can be improved.

[Effect]

The method of limiting the range of weight addition using a photoresist pattern using photolithography was also carried out by adding weight using the conventional wet plating method, but in the present invention, by using a photoresist with high plasma resistance, it is possible to limit the range of weight addition using a photoresist pattern using photolithography. A method was used in which metal was deposited and the metal film other than the limited portions was removed by lift-off of the photoresist.

〔Example〕

First, weight addition applied to the present invention will be explained.

FIG. 3 is a first example of weight addition in the present invention.

10 is a crystal wafer, 11 is an electrode film, and 13 is a protective film made of photoresist. If sputtering is performed on the surface in this state, a metal film as shown in 15 can be formed. Thereafter, by lifting off the metal film 15 along with the photoresist 13, the metal film can be left only in the portion 15 in the center of the drawing. These remaining 15 parts are 3 in Figure 1.
．． 4 and corresponds to the 8°9 part in FIG. The metal film 15 as an additional weight thus formed was extremely uniform and had good positional accuracy.

There are two methods for forming such a metal film on a tuning fork type crystal resonator. The first method is to add weight to the wafer before forming the external shape of the vibrator. The other method is to form the external shape of the vibrator by etching the crystal, measure the frequency on the wafer, and then coat the entire vibrator with photoresist 13 to form a pattern, as shown in the cross-sectional view of Figure 4. After that, a second example of the method of adding weight by sputtering is shown in FIG. 4, where 18 is a crystal vibrating part, 11 is an electrode film, 13 is a photoresist, and 15 is a metal film attached as an additional weight. It is. This metal Wj
415 can be formed using a vapor deposition method if necessary. Here, if the metal film is lifted off together with the photoresist, only a predetermined portion of the metal film remains. Due to the nature of crystal oscillators, as the added weight increases, the frequency decreases.
Using the method described above, a weight is added to a predetermined position of a vibrator on a wafer whose frequency is known, and the frequencies of all the vibrators are set to be equal to or lower than the target value.

After that, the frequency is increased by laser trimming,
The frequency is adjusted for each individual vibrator.

This method can also be applied to long-side longitudinal oscillators.

In the GT-cut crystal resonator as well, frequency adjustment is performed by laser trimming instead of frequency adjustment using the conventional vapor deposition method. Adjustments are made while the metal added in the present invention is evaporated by laser trimming.

This method greatly improved the accuracy of the adjusted position.

〔Effect of the invention〕

In addition, the present invention brings about the following effects.

■Additional weight for trimming the frequency adjustment section can be made uniform.

A desired weight can be added to a vibrator with a known zero frequency.

■Can reduce the use of harmful chemical solutions such as Metsuki liquid.

■By accurately determining the position of the added weight, trigging accuracy has been improved, and frequency and temperature characteristic adjustment accuracy has been improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the external shape and frequency adjustment section of a tuning fork type crystal resonator to which the present invention is applied, and FIG. 2 is a perspective view showing the external shape and frequency adjustment section of a CT-cut crystal resonator to which the present invention is applied. 3 are sectional views showing a first example of Ii amount addition according to the present invention, and FIG. 4 is a sectional view showing an example of a weight adding brush 2 according to the present invention. ... Vibrating section... Frequency adjusting section... Supporting section... Vibrating section... Frequency and temperature characteristic adjusting section... Crystal wafer... Electrode film 13... Resist 15... Metal film 18...・More than vibrating part

Claims (1)

[Claims] In a method of adding a heavy object to the frequency adjustment section of a crystal resonator formed by photolithography, the addition of the heavy object is performed by a dry method such as sputtering or vapor deposition, and the range of the addition is determined by plasma resistance using photolithography. 1. A method for adding a heavy object to a crystal resonator, characterized in that the method is limited by a resist pattern having a resist pattern.