JP2006129126A - Device and method for forming film on spherical material and manufacturing method of surface acoustic wave element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film forming method and a film forming device which form a uniform film in a region to which photo lithography process is applied for the purpose of forming a propagation path or an electrode pattern, etc. of resist films, a sensitive film, etc. on a surface of spherical material to be coated in manufacturing process of a spherical surface acoustic wave element. <P>SOLUTION: The film forming device of the spherical material comprises a rotation means 30 which rotates a rotation supporter 31; and a means which mounts the spherical material 10 fixing in a position departed from the rotation axis of the center of the rotation supporter 31, and forms a uniform thickness film covering the transmission path region (a circular region) by fixing the spherical material 10 on a material supporter 41 which is installed departed position from a center of the rotation axis of the rotation supporter 31, and rotating the spherical material about a rotation axis center. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for forming a coating film such as a sensitive film and a resist on a spherical base material that is a base material for a spherical surface acoustic wave element, and a method for manufacturing a surface acoustic wave element having a sensitive film formed thereon.

  2. Description of the Related Art A surface acoustic wave element has been well known as a device that generates surface acoustic waves on a substrate and receives surface acoustic waves generated on the substrate.

  In a conventional surface acoustic wave device, a pair of interdigital electrodes are provided on a flat substrate. The substrate is formed of a piezoelectric material, or a piezoelectric film is provided between the interdigital electrode and the substrate, and a high frequency voltage is supplied to one interdigital electrode so that the electrodes are aligned. Excitation of surface acoustic waves. The other interdigital electrode is arranged in the propagation direction of the surface acoustic wave and receives the surface acoustic wave.

  The surface acoustic wave element is used for a delay line, an oscillation element or a resonance element for a transmitter, a filter for selecting a frequency, a chemical sensor, a biosensor, a remote tag, or the like.

As a method for increasing the accuracy of a surface acoustic wave element, a spherical surface acoustic wave element that propagates a surface acoustic wave to the surface of a spherical base material and makes the base material circulate many times is known (for example, see Patent Document 1). .
As shown in FIG. 11, a spherical surface acoustic wave element is prepared by preparing a base material made of a single crystal of a crystal having a spherical surface, and using, for example, a comb-like electrode or the like, whereby a surface acoustic wave is generated in a certain direction. The surface of the sphere is utilized by utilizing the fact that the energy of the elastic wave excited in the form of a beam on the surface of the sphere propagates in a ring shape due to the geometric characteristics of the surface of the sphere, making it less susceptible to diffraction. This is an element that circulates a surface acoustic wave in multiple layers.
The width of the annular path (beam width) when the surface acoustic wave circulates on the spherical surface can be controlled within a certain range, and when the diameter of the surface of the sphere and the wavelength of the surface acoustic wave have a predetermined relationship It is also possible to design so that it does not change at all.

  The precondition for using the surface acoustic wave circulation phenomenon on the surface of the sphere is the region on the surface of the sphere where the surface acoustic wave circulates (hereinafter referred to as the propagation path). If there is a change, the surface acoustic wave is reflected at the boundary, making it difficult to wrap around multiple times.

  This is because the sensitive film of the spherical surface acoustic wave element that evaluates the environment by changing the elastic physical properties according to the external environment or changing the propagation of elastic waves by adsorbing gas substances etc. on the surface of the propagation path. This also occurs when the thickness changes greatly along the propagation path.

  In addition, increasing the film thickness and absorbing surface acoustic waves greatly affects its performance. If the propagation attenuation is large at the time of propagation, a long-distance surface acoustic wave cannot be propagated, resulting in a decrease in measurement sensitivity when measuring the propagation speed from the required time for a predetermined orbit.

  Furthermore, it is possible to create a hydrogen sensor by forming a palladium metal film on the propagation path, but it takes time for hydrogen to reach the deep state of the palladium film and reach an equilibrium state, so as thin a sensitive film as possible is formed. It is requested to do. This also applies to the formation of a sensitive film made of an organic film.

Similar problems occur in the manufacturing process of the spherical surface acoustic wave device.
When a surface acoustic wave is circulated in its propagation path, it is generally desirable that the surface be provided with a substantially uniform thickness over the peripheral circuit when the surface has a film structure.
As a method of forming a film uniformly over the entire circumference of the circulation path, a film is formed on the surface of the spherical substrate while rotating the spherical substrate, for example, while dropping a film material with an inkjet nozzle. However, it takes time.

In addition, as shown in FIG. 12A, it is conceivable to form a film using a conventional spin coater several times along the propagation path of the spherical base material 10. From the viewpoint of uniformity on the propagation path because the A region is thin and the B region is formed in a thick annular shape by centrifugal force, as shown in FIG. 12 (b). Is a problem.
Also, the C region is formed very thick because the resist accumulates due to gravity and surface tension, and a process for removing this later is required.
In this example, there is only one center of rotation, and only one spherical base material can be formed by one spin coating, and there is a problem in mass productivity.

In a spherical surface acoustic wave device, interdigital electrodes are formed by forming a thin film of chromium and gold, for example, by vapor deposition on the surface of a spherical substrate, and then applying a resist to form a photosensitive layer, and then exposing, developing, and etching. However, as shown in FIG. 11, it is necessary to form the interdigital electrodes on both sides, that is, on both sides of the propagation path region.
In this case, as shown in FIG. 13, it is necessary to accurately form an electrode extraction pattern over a substantially semicircle or more of the spherical base material. In this case, a uniform resist film in a region of the semicircular or more of the spherical base material. It is clear that the formation of is difficult with a spin coater as described above.
JP 2003-115744 A

  The present invention has been made in view of the above problems, and in the process of manufacturing a spherical surface acoustic wave element, a coating such as a resist or a sensitive film is applied to the surface of a spherical base material that is an object to be coated. It is an object of the present invention to provide a film forming method and a film forming apparatus for forming a uniform film in a region to which a photolithography process intended to be formed is applied.

  In order to achieve the above object, according to the present invention, in claim 1, at least a spherical base material that is an object to be coated is fixedly mounted at a location separated from the rotation shaft of the rotary support, An apparatus for forming a coating film on a spherical base material is provided that includes a rotating means for dropping a chemical solution as a material onto the spherical base material and rotating a rotary support.

  According to a second aspect of the present invention, in the method of forming a film on the surface of the spherical substrate by moving the chemical solution along the spherical surface by centrifugal force, at least the spherical substrate that is the object to be coated is rotated by the rotating support. To a spherical base material comprising: a step of fixing and mounting at a location spaced from the shaft; a step of dripping a chemical solution as a coating material material onto the spherical base material; and a step of rotating the rotary support. This is a film forming method.

  According to a third aspect of the present invention, in the method for forming a film on a spherical base material according to the second aspect, the chemical solution is a photosensitive resist material used for forming a fine pattern.

  Further, in claim 4, the step of dropping the chemical solution onto the spherical base material is performed while rotating the spherical base material around the central axis of the maximum outer peripheral line of the spherical base material. The method for forming a film on the spherical base material described in 2 or 3 is used.

  Furthermore, in claim 5, the surface acoustic wave element in which electroacoustic conversion means for exciting / detecting surface acoustic waves is formed in an annular region including the maximum outer peripheral line of the spherical base material is used as the spherical base material. The center line of the maximum outer peripheral line is fixed in an arrangement perpendicularly intersecting the rotation axis of the rotating support, and a chemical solution that is a material of the sensitive film is dropped, and the rotating support is rotated, thereby rotating the rotating region, A surface acoustic wave element manufacturing method is characterized by forming a sensitive film that changes the propagation state of a surface acoustic wave in accordance with changes in the surrounding environment.

According to the method and apparatus for forming a film on a spherical substrate of the present invention, a film such as a resist or a sensitive film is uniformly formed in a region corresponding to the propagation path of the spherical substrate or the spherical surface acoustic wave element. Can do.
In addition, since the centrifugal force on the rotating shaft of the rotating means is used, a large number of spherical base materials can be mounted, and a coating device for forming a spherical base material with high mass productivity can be provided.
In addition, the propagation state of the surface acoustic wave is changed by forming a sensitive film on the surface of the spherical surface acoustic wave element by using the film forming apparatus for the spherical substrate and the method for forming the film on the spherical substrate of the present invention. It is possible to easily obtain a spherical surface acoustic wave element that can be used.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a schematic configuration diagram showing an embodiment of a film forming apparatus for a spherical base material according to claim 1. The apparatus for forming a coating film on a spherical base material of the present invention comprises a rotating means 30 for rotating the rotary support 31 and a means for fixing and mounting the spherical base material 10 at a location separated from the rotational axis of the rotary support 31. Have.
In the present invention, the spherical base material may be a base material having a spherical surface at least at a part thereof. For example, a part of the spherical shape may be missing or have a flat surface.

A method for forming a film on the spherical base material according to claim 2 using the film forming apparatus will be described.
The spherical base material 10 is fixed to a base material support base 41 installed at a location away from the rotation axis of the rotary support 31, and a chemical solution, which is a film forming material, is dropped onto the spherical base material 10. By rotating with a rotating means, a film can be formed on the surface of the spherical substrate 10 by centrifugal application (by forming a film by applying a centrifugal force to the chemical solution of the spherical substrate). FIG. 2 shows the arrangement of the coating formed in the propagation path region (annular region) of the spherical base material 10, which is in the normal direction of the maximum outer circumference line intersecting with the propagation path region of the spherical surface acoustic wave element. By rotating the spherical base material about the rotation axis center, a centrifugal force is applied to the surface that crosses the region equally over the propagation path region of the spherical surface acoustic wave element, so that the coating has a uniform thickness over the propagation path region. It is possible to form a film. Since the centrifugal force can generate the force that causes the most chemical liquid to flow in the propagation path region, a very thin and uniform film can be formed in the propagation path region.
In the present invention, the surface acoustic wave is a general term for an acoustic wave that propagates by concentrating elastic energy along the material surface, and includes a leaky surface acoustic wave, a pseudo surface acoustic wave, an SH wave, a love wave, a corridor wave, and the like. In addition, an element using them is also expressed as a surface acoustic wave element or a spherical surface acoustic wave element.

More specifically, the spherical base material 10 is fixed to the base material support base 41 installed at a position away from the central rotational axis of the rotary support 31 shown in FIG. 1, and the spherical base material is rotated about the rotational axis center. By doing so, a film having a uniform thickness is formed over the propagation path region.
In this arrangement, the propagation path region where the film is formed is in the vicinity of the equator with the Z axis of the spherical base material 10 of FIG.
Here, an example in which two spherical base materials 10 are arranged on the rotary support 31 is shown. However, a large number of spherical base materials 10 are arranged at concentric positions on the rotary support 31 and film formation is performed collectively. Can do. For fixing the spherical base material 10 to the base material support base 41, vacuum suction or a removable adhesive can be used.

FIGS. 3A to 3B are explanatory views showing the spread state of the chemical solution when the chemical solution is dropped onto the spherical base material 10.
When the chemical liquid is dripped from the chemical liquid supply nozzle 51 as shown in FIG. 3A, it thickens downward according to gravity, but as it rotates at a high speed, the chemical liquid 61 has a centrifugal force as shown in FIG. It is stretched thinly by receiving force in the working direction. Gravity is smaller than centrifugal force, and a uniform film is formed in the propagation path region.

In the method for forming a film, since a ring region that is not applied remains even if the chemical solution is applied over the annular region of the spherical base material 10 even if the chemical solution is moved by centrifugal force, a relatively large amount of the chemical solution needs to be dropped. There is.
As a method for preventing this, as shown in FIG. 4A, first, a chemical solution is dropped from the chemical solution supply nozzle 51 in a horizontal position, and then, as shown in FIG. Then, as shown in FIG. 4C, the chemical solution is spread by vibrating in a horizontal plane, and as shown in FIG. 4D, the chemical solution reservoir 62 is formed on the surface of the spherical base material 10. The chemical solution can be saved by performing centrifugal coating after forming the film.

Further, in the invention according to claim 4, as a method of dropping the chemical liquid from the chemical liquid supply nozzle 51 and forming the chemical liquid reservoir 62 on the surface of the spherical base material 10, the spherical base material 10 is rotated in advance as shown in FIG. However, by dropping the chemical solution from the chemical solution supply nozzle 51, a necessary amount of the chemical solution reservoir 62 can be formed at a necessary location.
In this method, the amount of chemical used can be set to the minimum and the chemical pool can be formed uniformly, so that the chemical fluid flow process in the subsequent centrifugal coating process is stabilized, and as a result, a more uniform film can be formed. . FIG. 6 shows a state in which a uniform film 64 is formed on the surface of the spherical substrate 10.

According to the above-described film forming method, a uniform film can be formed on the surface of the spherical base material 10 as shown in FIG. 6, but the chemical solution reservoir 63 is formed in the region where the base material support base 41 and the spherical base material 10 are fixed. A process that occurs and removes it is required.
Therefore, as shown in FIG. 7, a through hole 44 is formed in a region where the base material support base 41 and the spherical base material 10 are fixed, and the chemical liquid pushed out by centrifugal coating is passed through the through hole 44 to an auxiliary container or the like. By taking in, a chemical | medical solution reservoir can be eliminated in the area | region where the base-material support stand 41 and the spherical base material 10 were fixed.

FIG. 8 shows an example of a film forming apparatus for forming a film on the surface of many spherical base materials 10.
The coating film forming apparatus fixes a large number of spherical base materials 10 to a pendulum type support material 42 attached to the upper and lower rotary plates 32 with the central rotational axis of the rotary plate 32 as the center of rotation, and applies a chemical solution to the spherical base material 10. By dropping and rotating the rotating plate 32, a coating can be formed on the surface of many spherical base materials 10 at a time by centrifugal coating.
In this apparatus, for example, if a chemical solution is showered or sprayed by using a nozzle under a chemical droplet on the pendulum type support member 42 on the outer side from the center rotational axis position, the chemical solution is dropped onto the spherical base material 10 and centrifuged. It can be done very efficiently.

FIG. 9A shows another example of a film forming apparatus that forms a film on the surface of the spherical base material 10.
The coating film forming apparatus rotates the spherical base material 10 fixed on a pendulum type support member 43 connected to the rotary arm 33 in a pendulum shape by the rotary arm 33, so that the surface of the spherical base material 10 is obtained by centrifugal coating. A uniform coating 64 is to be formed. In this example, the rotary arm 33 and the pendulum type support material 43 form a rotary support.
FIGS. 9B to 9D show the state of film formation until the film is formed by dropping the chemical solution.
First, in a stationary state as shown in FIG. 9B, a chemical solution is dropped from the chemical solution supply nozzle 51 onto the spherical base material 10 fixed on the pendulum type support member 43, and a chemical solution reservoir 62 is formed on the spherical base material 10. Form.
Next, the chemical reservoir 62a is formed in a state where the chemical reservoir 62 is extended on the upper part of the spherical base material 10 in a low-speed rotation state as shown in FIG. 9C.
Further, a uniform coating 64 is formed on the surface of the spherical substrate 10 by performing centrifugal coating in a high-speed rotation state as shown in FIG.
The advantage of film formation using this apparatus is that a uniform film can be formed over the entire circumference of the annular region of the spherical substrate 10 simply by dropping the chemical solution onto the upper surface of the spherical substrate 10 in a stationary state.

Hereinafter, the manufacturing method of the spherical elastic wave element concerning Claim 5 is demonstrated using the film formation apparatus and film formation method of this invention.
Here, there are a case where the spherical substrate 10 is manufactured using a non-piezoelectric substrate and a case where the spherical substrate 10 is manufactured using a piezoelectric substrate. Here, a method for manufacturing a spherical surface acoustic wave element using a piezoelectric substrate is used. Will be described.
First, a piezoelectric crystal substrate such as quartz is prepared as the spherical substrate 10.
When creating a surface acoustic wave device with this configuration, there is a specific propagation path through which the surface acoustic wave defined by the crystal axis can be excited and circulated. It is necessary to manufacture according to the axis.

Next, a conductive film (usually a metal film) for forming interdigital electrodes is formed by vapor deposition or sputtering at a position corresponding to a predetermined crystal plane of the spherical substrate 10.
Next, a photoresist is formed on the surface of the spherical base material 10 on which the conductive film is formed using the film forming apparatus and the film forming method of the present invention.

  Next, a series of patterning processes such as pattern exposure and development are performed on the surface of the spherical base material 10 on which the photoresist has been formed using a photomask to form a resist pattern.

Next, the conductive film is etched with a dedicated etching solution using the resist pattern as a mask, the resist pattern is peeled off, and an elastic surface is formed on the propagation path region formed of the annular region including the maximum outer peripheral line of the spherical substrate 10. A spherical surface acoustic wave element in which electroacoustic conversion means for exciting / detecting waves is formed can be produced.
The most suitable electroacoustic transducer used for spherical surface acoustic waves is an interdigital electrode (or comb-shaped electrode), which is usually formed in contact with a piezoelectric substrate, and a voltage is applied to the electrode. Thus, an elastic field can be generated by applying an electric field to the surface of the piezoelectric film or the piezoelectric spherical base material.

  Unlike the above patterning method, a lift-off process in which a resist pattern is formed in advance on a spherical substrate, a metal film is formed, and then the resist pattern is peeled off to produce an interdigital electrode. A film forming apparatus and a film forming method can be developed.

Next, using the coating film forming apparatus and the coating film forming method of the present invention, on the propagation path around which the surface acoustic wave of the spherical surface acoustic wave element circulates, the surrounding environment changes (for example, temperature, humidity, pressure, gas components, and the like) A spherical surface acoustic wave device with a sensor that can change the propagation state of surface acoustic waves by forming a sensitive film that changes the surface acoustic wave propagation characteristics (circular velocity, attenuation rate, etc.) Can be made.

  On the other hand, various shapes of spherical surface acoustic wave elements using interdigital electrodes have been proposed, and the present invention does not describe them in detail, but even if they are directly formed on the surface of the spherical base material 10 having piezoelectricity, Alternatively, as shown in FIG. 10, by using the coating film forming apparatus and the coating film forming method of the present invention, the support base material 44 is brought close to the surface of the spherical base material 10 on which the sensitive film is formed (with a gap). The interdigital electrodes formed on each other are arranged to face each other, so that an electric field is exerted on the surface of the spherical base material 10 having piezoelectricity, and thus an electric field pattern similar to the interdigital electrode pattern is formed. It is also possible to excite an elastic wave.

  As described above, a uniform resist film and sensitive film can be obtained easily and efficiently by forming a film on the surface of the spherical substrate using the film forming apparatus and the film forming method of the present invention.

It is explanatory drawing which shows one Example of the film formation apparatus to the spherical base material of this invention. FIG. 3 is an explanatory diagram showing an arrangement of a film formed in a propagation path region (annular region) of a spherical base material 10. (A)-(b) is explanatory drawing which shows the spreading state of a chemical | medical solution when a chemical | medical solution is dripped at the spherical base material 10. FIG. (A)-(d) is explanatory drawing which dripped a chemical | medical solution to the spherical base material 10, and shows the formation state of a chemical | medical solution pool. 4 is an explanatory view showing a state in which a chemical liquid pool is formed on the spherical base material 10 by rotating the base material support base. FIG. 3 is an explanatory view showing an example of a state in which a film is formed on the spherical base material 10. FIG. FIG. 3 is an explanatory diagram illustrating an example of a state in which a through hole is formed in a base material support base and a film is formed on a spherical base material. It is explanatory drawing which shows the other Example of the film formation apparatus to a spherical base material. (A) is explanatory drawing which shows the other Example of the film formation apparatus to a spherical base material. (B)-(d) is explanatory drawing which shows the formation state of a chemical | medical solution reservoir and a film. It is explanatory drawing which shows an example of the spherical surface acoustic wave element produced using the film formation apparatus and film formation method of this invention. It is explanatory drawing which shows an example of a spherical surface acoustic wave element. (A) And (b) is explanatory drawing which shows an example of the film formation to the spherical base material using a spin coater. It is explanatory drawing which shows the positional relationship of the interdigital electrode and extraction electrode in a spherical surface acoustic wave element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Spherical base material 30 ... Rotating means 31 ... Rotating support body 32 ... Rotating plate 33 ... Rotating arm 41 ... Base material support base 42, 43 ... Pendulum type support material 44 ... Support material 51 ... ... Chemical solution supply nozzle 61 ... Chemical solution 62, 63 ... Chemical solution reservoir 64 ... Film

Claims (5)

  A means for fixing and mounting at least a spherical base material, which is an object to be coated, at a location spaced from the rotation axis of the rotary support, and a chemical solution as a coating material is dropped on the spherical base to rotate the rotary support. An apparatus for forming a coating on a spherical base material comprising a rotating means. In a method of forming a film on the surface of a spherical substrate by migrating a chemical solution along the spherical surface by centrifugal force,
Fixing and mounting at least a spherical base material, which is an object to be coated, at a position away from the rotation axis of the rotary support, dropping a chemical solution as a coating material onto the spherical base, and rotating the rotary support A method of forming a film on a spherical base material.   3. The method for forming a film on a spherical substrate according to claim 2, wherein the chemical solution is a photosensitive resist material used for forming a fine pattern.   4. The spherical base according to claim 2, wherein the step of dripping the chemical solution onto the spherical base material is performed while rotating the spherical base material about a central axis of a maximum outer peripheral line of the spherical base material. A method for forming a film on a material.   A surface acoustic wave element in which electroacoustic conversion means for exciting / detecting surface acoustic waves is formed in an annular region including the maximum outer peripheral line of the spherical base material, and the center line of the maximum outer peripheral line of the spherical base material rotates. Fixing the substrate perpendicularly to the rotation axis of the support, dropping the chemical solution, which is the material of the sensitive film, and rotating the rotation support, the surface area wave of the surface wave is applied to the annular region according to the surrounding environment change. A method of manufacturing a surface acoustic wave device, comprising forming a sensitive film that changes a propagation state.

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