JP2005295042A - Method of manufacturing high-frequency crystal vibration plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a high-frequency crystal vibration plate having a vibration characteristic in an exciting vibration region because it has no difference in processing shape due to a crystal axis direction generated in etching processing and an etching portion (especially, wall surface portion in a reinforced portion between an excitation vibration region and a reinforcing portion) can be formed into a desired form. <P>SOLUTION: The method of manufacturing a high-frequency crystal vibration plate comprises a process of forming a buffer layer on a substrate and epitaxially growing a first crystal thin film thereon; a process of forming a resist film or the like on the entire surface of the first crystal thin film and forming the resist film into a desired shape by a photolithography method; a process of epitaxially growing a second crystal thin film on the resist film; a process of removing the resist film together with the second crystal thin film; and a process of forming each type of electrode film suitable for each crystal blank plate on the first and second crystal thin films, after that, cutting the thin films at desired positions to form a plurality of high-frequency crystal vibration plates. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a crystal diaphragm, and more particularly to a method for manufacturing a high-frequency crystal diaphragm that excites at a high frequency.

  Conventionally, a quartz plate, a quartz oscillator, and the like generally use a quartz plate called a quartz plate and a thin plate made of various electrode films. With regard to the crystal base plate made of this crystal, the recent trend is demanding extremely rapid miniaturization, thinning, and high frequency of the mounted components with the transmission system device in the communication field as the core.

  Conventionally, the quartz plate is a growth method called a hydrothermal growth method in which a pressure-resistant vessel called an autoclave is filled with an alkaline aqueous solution such as sodium carbonate or sodium hydroxide, and the state in the previous autoclave is set to a high temperature and high pressure state. In general, the artificial quartz grown by the above method is cut into a plate shape and further polished to a desired thickness to finally form a small thin quartz base plate.

  Further, the quartz base plate has a characteristic that in the thickness shear vibration mode, the excitation frequency increases as the thickness of the quartz base plate decreases. However, as the quartz base plate becomes thinner, the strength of the base plate becomes weaker, and due to the thin processing limit by the polishing means, the reinforcement part of the quartz base plate is formed by polishing, and the excitation vibration region of the quartz base plate is etched. A quartz crystal diaphragm as shown in FIG. 4 is used which is formed to have a thickness (several μm or less) for exciting a desired frequency and on which various electrode films are formed.

  The following literature is disclosed about the manufacturing method of the above-mentioned crystal diaphragm.

Shotaro Okano "Crystal Frequency Control Device" Techno Inc. 1995 JP-A-10-145179

  In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

  However, in the hydrothermal growth method described above, a period of at least 2 to 3 months is required for the growth of the artificial quartz crystal, and in the course of the cutting and polishing process until a quartz base plate having a desired shape is produced from the artificial quartz crystal. Has a problem that it is very inefficient because a quantity of quartz that reaches approximately 90% or more of the weight of the original artificial quartz is discarded as cutting scraps.

  In addition, the reinforcing part of the quartz base plate is formed by polishing, the excitation vibration region of the quartz base plate is formed to a thickness that excites a desired high frequency by etching, and various electrodes are provided on the surface. In the quartz crystal diaphragm as shown in FIG. 4 produced by the method, as disclosed in FIG. 4B, the etching location (particularly the excitation vibration region 41 and the reinforcement) due to the etching anisotropy for each crystal axis of the quartz crystal. It is difficult to process the reinforcing portion inner wall surface portion between the portion 42 and a desired shape, and the problem of excitation characteristics resulting from the failure to obtain the desired shape is also a problem. In particular, as the shape of the quartz base plate becomes smaller, the influence on the characteristics due to the difference in the processing shape depending on the crystal axis direction generated during the etching processing increases.

  Furthermore, even in the thickness processing of the excitation vibration region by etching processing, there is a limit to the thinness that can be processed, which may hinder further high frequency.

The present invention has been made to solve the above-described problems, and includes a rectangular excitation vibration region for exciting a desired frequency, and a reinforcement thicker than the thickness of the excitation vibration region around the excitation vibration region. And an excitation electrode on the front and back main surfaces of the excitation vibration region, an extraction electrode extending from the excitation electrode to the reinforcement portion, and an extraction on the main surface of the reinforcement portion. In the method for manufacturing a high-frequency crystal diaphragm, comprising an electrode film for external connection conducted with an electrode,
Using a manufacturing apparatus that epitaxially grows a crystal thin film that becomes a plurality of crystal base plates on a substrate by vapor phase growth,
Forming a buffer layer on the substrate, and epitaxially growing the first crystal thin film on the buffer layer with a thickness that excites at a desired frequency;
Forming a resist film on the entire upper surface of the first crystal thin film, and forming a transparent protective film on the entire upper surface of the resist film;
The resist film is processed by a photolithography method, and the resist film and the protective film are formed into a film pattern in which the resist film and the protective film remain in a plurality of locations that serve as excitation vibration regions of the individual crystal base plates in the first crystal thin film. And the process of
The second crystal thin film is epitaxially grown to a thickness that produces a desired strength on the film pattern in which the resist film and the protective film remain in the excitation vibration region, and on the first crystal thin film not coated with the film pattern. A process of nurturing,
Removing the resist film from the first crystal thin film together with the protective film and the second crystal thin film grown on the protective film;
Peeling the substrate and the buffer layer from the first quartz thin film to form a quartz thin film sheet composed of the first quartz thin film and the second quartz thin film;
Forming an excitation electrode film, an extraction electrode film, and an external connection electrode film on the crystal thin film sheet so as to match each crystal element plate, and then cutting at a desired cutting position to form a plurality of crystal diaphragms And a method of manufacturing a high-frequency crystal diaphragm.

  By using the manufacturing method of the high-frequency crystal diaphragm disclosed in the present invention, it is possible to obtain a high-frequency crystal base plate having a desired shape without processing by polishing and etching, and the cutting process is a minimum man-hour. It is possible to remarkably reduce the generation of processing waste that has occurred during the processing, and the production efficiency is significantly increased.

  In addition, when manufacturing a crystal diaphragm having an outer shape corresponding to high-frequency vibration, the present invention does not use etching processing as a means for creating an excitation vibration region. Since there is no difference and the desired shape can be formed with high accuracy, the vibration characteristics in the excitation vibration region are good. Further, the deterioration of the vibration characteristics due to the miniaturization of the quartz diaphragm can be extremely reduced.

  Therefore, the present invention has an effect of providing a quartz diaphragm that is high in production efficiency and excellent in excitation characteristics and suitable for high frequency operation.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram illustrating a part of a method for manufacturing a high-frequency crystal diaphragm according to the present invention using a partial cross-sectional view of the crystal diaphragm. FIG. 2A is a plan view showing an embodiment of a quartz crystal plate manufactured by the process disclosed in FIG. FIG. 2B is a cross-sectional view taken along the cutting line A1-A2 shown in FIG. FIG. 3 shows an epitaxial growth of a crystal thin film used in a part of the method for manufacturing a crystal diaphragm according to the present invention on a substrate 11 made of sapphire, silicon, gallium arsenide (GaAs) or the like. It is a schematic schematic diagram of the apparatus for this.

  In each figure, a part of the structure is not shown for the sake of clarity. Each dimension is also partially exaggerated, and in particular, the thickness of a crystal epitaxial thin film, an electrode film, etc. is remarkably exaggerated. Furthermore, the same reference numerals in the drawings indicate the same objects.

  In the step of FIG. 1A, a buffer layer 12 is first formed on a substrate 11 such as sapphire, silicon, or gallium arsenide (GaAs). This buffer layer 12 is formed in order to easily peel the first crystal thin film from the substrate 11 in a later step.

  In the next step shown in FIG. 1B, the first crystal thin film 13 is epitaxially grown on the buffer layer 12 to a thickness that excites a desired fundamental frequency using the apparatus disclosed in FIG. For example, in the case of a quartz thin film grown in the same crystal direction as a conventional quartz base plate cut out by so-called AT-cut, in order to excite a high frequency fundamental wave vibration of 600 MHz in a thickness shear vibration mode, the thickness of the quartz thin film is about 2 μm.

  In the next step of FIG. 1C, a resist film 14 is formed on the first crystal thin film 13 formed to have a desired thickness, and a transparent protective film 15 is further formed on the resist film 14.

  In the next step of FIG. 1D, a mask (not shown) for exposing the resist film 14 in a desired pattern is disposed on the protective film 15 formed on the resist film 14, and above the mask. More exposure. After the exposure, development is performed to remove unnecessary resist film and protective film. FIG. 1D illustrates a state in which the resist film and the protective film remain in the portion that becomes the excitation vibration region of the quartz plate after the removal.

  In the next step of FIG. 1E, a second crystal thin film 16 is formed on the remaining protective film 15 and on the first crystal thin film 13 exposed by removing the resist film 14 and the protective film 15. Epitaxial growth is performed using the apparatus disclosed in FIG. The thickness of the second crystal thin film 16 is necessary for holding the excitation vibration region formed by the first crystal thin film 13 and cutting the crystal diaphragm alone when it is cut into individual crystal diaphragms in a later process. The thickness is sufficient to produce the required strength.

  In the next step of FIG. 1 (f), the resist film 14 remaining on the first crystal thin film 13, the protective film 15, and the second crystal thin film 16 formed on the protective film are formed on the first crystal thin film 13. Remove from. After the removal, the first crystal thin film 13 and the second crystal thin film 16 formed on the portion other than the excitation vibration region of the first crystal thin film 13 remain on the substrate 11 and the buffer layer 12.

  In the next step of FIG. 1G, the substrate 11 and the buffer layer 12 are peeled from the first crystal thin film 13 to form a crystal thin film sheet composed of the first crystal thin film 13 and the second crystal thin film 16. To do. In the present invention, since the first crystal thin film is not directly formed on the substrate, the substrate 11 and the like can be easily peeled off. The substrate 11 is reused and used for growing another crystal thin film. The crystal thin film sheet includes an excitation electrode film 17 and a lead on the excitation vibration region front and back main surfaces of the first crystal thin film 13, the back surface of the first crystal thin film 13, and the surface of the second crystal thin film 16. An external connection electrode film 19 that is electrically connected to the electrode connection pads on the container side on which the electrodes 18 and the crystal diaphragm are mounted is formed in a desired shape at a position corresponding to each crystal diaphragm.

  Next, in the step of FIG. 1 (h), the crystal thin film sheet composed of the first crystal thin film 13 and the second crystal thin film 16 is cut along the cutting line C shown in FIG. A crystal diaphragm 10 having a high frequency fundamental wave is formed. A dicing saw or the like is used for cutting.

  FIG. 2 shows an embodiment of a high-frequency fundamental crystal resonator 10 manufactured in the above-described steps. FIG. 2B is a cross-sectional view taken along the cutting line A1-A2 shown in FIG. 2A. The excitation vibration region 21 formed of the first crystal thin film and the first crystal The boundary portion between the part of the thin film and the reinforcing part 22 formed of the second crystal thin film has a symmetrical shape, and the side shape of the reinforcing part 22 on the side of the excitation vibration region is flat and is in the excitation vibration region 21. On the other hand, since it is formed vertically, it is difficult to adversely affect the vibration characteristics of the excitation vibration region 21.

  In the above-described embodiment, the example in which the vibration order of the thickness shear vibration excited by the excitation vibration region of the crystal plate 10 is the fundamental wave (first order) is disclosed, but other orders (for example, third order, fifth order, etc.) are disclosed. The so-called overtone vibration in the method for manufacturing a crystal diaphragm that excites the excitation vibration region in the excitation vibration region can provide the same effects as the embodiment.

FIG. 1 is a process diagram illustrating a part of the method for manufacturing a high-frequency crystal diaphragm according to the present invention using a partial cross-sectional view of the crystal diaphragm. 2 illustrates the form of the high-frequency crystal diaphragm manufactured in the process disclosed in FIG. 1, FIG. 2 (a) is a plan view from above, and FIG. 2 (b) is illustrated in FIG. 2 (a). It is sectional drawing at the time of cut | disconnecting by cutting line A1-A2. FIG. 3 shows an apparatus for a process of performing epitaxial growth of a crystal thin film on a substrate of sapphire, silicon, gallium arsenide (GaAs) or the like mounted therein, in the method for manufacturing a high-frequency crystal diaphragm according to the present invention. FIG. FIG. 4 shows the form of a high-frequency crystal diaphragm manufactured using a conventional manufacturing method. FIG. 4 (a) is a plan view from above, and FIG. 4 (b) is shown in FIG. 4 (a). It is sectional drawing at the time of cut | disconnecting by cutting line B1-B2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, Quartz diaphragm 11, Substrate 12, Buffer layer 13, 1st quartz thin film 14, Resist film 15, Protective film 16, 2nd quartz thin film 17, Excitation electrode film 18, Extraction electrode film 19, For external connection Electrode film 21, excitation vibration region 22, reinforcement

Claims (1)

A rectangular excitation vibration region for exciting a desired frequency, and a reinforcing portion thicker than the excitation vibration region around the excitation vibration region are formed of a single crystal material, and the front and back sides of the excitation vibration region A high frequency comprising: an excitation electrode on a surface; an extraction electrode extending from the excitation electrode to the reinforcement portion; and an external connection electrode film electrically connected to the extraction electrode on a main surface of the reinforcement portion. In the manufacturing method of the crystal diaphragm,
Using a manufacturing apparatus that grows a crystal thin film that becomes a plurality of quartz base plates on a substrate by vapor phase growth,
Forming a buffer layer on the substrate, and epitaxially growing a first crystal thin film on the buffer layer to a thickness that excites at a desired frequency;
Forming a resist film on the entire upper surface of the first crystal thin film, and forming a transparent protective film on the entire upper surface of the resist film;
The resist film is processed by a photolithography method, and the resist film and the protective film remain at a plurality of locations serving as excitation vibration regions of the individual crystal element plates in the first crystal thin film. Forming a film pattern;
The second crystal thin film has a desired strength on the film pattern in which the resist film and the protective film remain in the excitation vibration region and on the first crystal thin film not coated with the film pattern. A process of epitaxial growth to a thickness at which
Removing the resist film from the first crystal thin film together with the protective film and the second crystal thin film grown on the protective film;
Peeling the substrate and the buffer layer from the first quartz thin film to form a quartz thin film sheet comprising the first quartz thin film and the second quartz thin film;
Forming an excitation electrode film, an extraction electrode film, and an external connection electrode film on the crystal thin film sheet so as to match each crystal element plate, and then cutting at a desired cutting position to form a plurality of crystal vibration plates A method for manufacturing a high-frequency crystal diaphragm, comprising:

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