JP2006333334A - Photo-mask for forming surface acoustic wave element, method of manufacturing surface acoustic wave element, and surface acoustic wave element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce fluctuations of frequency temperature characteristics between surface acoustic wave elements formed from the same wafer. <P>SOLUTION: The present invention relates to a photo-mask for exposing a photo-resist provided on a piezoelectric substrate, and a photo-mask 30 comprises, on a transparent substrate 32, the same electrode patterns 34 (34a-34c) of different directions corresponding to interdigital electrodes to be formed on the piezoelectric substrate. These electrode patterns 34 are to be selectively used when exposing the photo-resist in accordance with the fluctuations of frequency temperature characteristics of the surface acoustic wave elements caused by a position of the piezoelectric substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photomask for forming a surface acoustic wave element, and its characteristics change depending on a rotation angle (so-called in-plane rotation angle) along a surface of a piezoelectric substrate (piezoelectric wafer) cut out from a crystal block. The present invention relates to a photomask for forming a surface acoustic wave element suitable for manufacturing a surface acoustic wave element to be manufactured, a method for manufacturing the surface acoustic wave element, and the surface acoustic wave element.

  In recent years, electronic devices have been downsized, improved in performance, and increased in communication speed. In connection with this, high frequency of various electronic devices including communication devices has been achieved. Since these electronic devices are relatively easy to handle high frequencies, and are small and excellent in mass productivity, SAW resonators and SAW filters using surface acoustic wave elements are used. The surface acoustic wave device is widely used. In particular, since a surface acoustic wave element using quartz as a piezoelectric substrate has excellent temperature characteristics, a highly accurate surface acoustic wave device can be obtained. However, due to recent demands for higher frequency and higher accuracy of electronic equipment, development of surface acoustic wave devices with higher accuracy is desired. Therefore, the applicant of the present application has developed a surface acoustic wave device using a so-called in-plane rotating ST-cut quartz plate that is superior in frequency temperature characteristics to a surface acoustic wave device using an ST-cut quartz plate (for example, a patent). Reference 1). FIG. 4 is an explanatory diagram of a surface acoustic wave element using an in-plane rotating ST-cut quartz plate.

  In FIG. 4, an X axis, a Y axis, and a Z axis indicate crystal axes of quartz, respectively. The X axis is a so-called electric axis, the Y axis is a so-called mechanical axis, and the Z axis is a so-called optical axis. The ST-cut quartz plate 10 has a quartz Z-plate 12 with Euler angles (0 °, 0 °, 0 °) and an angle of (φ, θ, ψ) of θ = 113 ° around the X axis. It is obtained by cutting through 135 ° and cutting along the crystal axes (X, Y ′, Z ′) at this time. The in-plane rotated ST-cut quartz plate is a quartz plate obtained by rotating the ST-cut quartz plate 10 within the XY ′ plane that is the main surface of the ST-cut quartz plate 10.

  That is, the in-plane rotation ST-cut quartz plate rotates the ST-cut quartz plate 10 further about the Z ′ axis by ψ = ± (40 ° to 49 °), and the X axis is the X ′ axis and the Y ′ axis is the Y ″ axis. And a crystal plate cut out along the axis (X ′, Y ″, Z ′). The surface acoustic wave element 14 made of the in-plane rotating ST-cut quartz plate is manufactured so that the propagation direction of the surface acoustic wave is along the X ′ axis. The surface acoustic wave element 14 made of this in-plane rotated ST-cut quartz plate has a small frequency change rate with respect to a temperature change and extremely good temperature characteristics.

  However, the surface acoustic wave element 14 using this in-plane rotating ST-cut quartz plate is a case where the electrode thickness, inter-electrode pitch, electrode width, etc. of an IDT (Interdigital Transducer) 16 composed of interdigital electrodes are formed to be the same. Even in such a case, if the in-plane rotation angle ψ changes, the frequency, the frequency temperature characteristic, and the like differ. The surface acoustic wave element is not only formed from an in-plane rotating ST-cut quartz plate, but also made of an ST-cut quartz plate, or other piezoelectric material such as lithium tantalate or lithium niobate. However, it is known that the frequency and frequency temperature characteristics vary depending on the electrode film thickness, electrode width, electrode formation pitch, and the like of the IDT.

On the other hand, according to the research by the inventors, when a metal film (for example, an aluminum film) for an electrode is formed on a quartz wafer using a film forming apparatus such as a sputtering apparatus, the film thickness distribution is present in the wafer. The film thickness distribution varies depending on the film forming apparatus. For example, when a film is formed using a film forming apparatus (not shown), the film thickness distribution shown in FIG. 5 is shown. That is, the central portion 22 of the wafer 20 is a thick film region, the outer intermediate portion 24 is a thin film region, and the outer peripheral portion 26 of the wafer 20 is a medium film thickness region. This film thickness distribution shows the same tendency when the film forming conditions are constant. For this reason, the surface acoustic wave elements formed from the same wafer 20 vary in frequency and frequency temperature characteristics, making it difficult to form a highly accurate surface acoustic wave element. Patent Document 2 considers that the effective film thickness distribution becomes non-uniform by performing a process after film formation such as etching so that a predetermined film thickness distribution can be consciously obtained on the wafer. It is proposed to form a film. That is, in Patent Document 2, the film thickness is controlled by changing the distance between the wafer and the target.
JP 2003-258601 A JP 2002-275627 A

The method described in Patent Document 2 can control the film thickness distribution in the single wafer processing in which wafers are formed one by one. However, since the method described in Patent Document 2 is a single-wafer process, it takes a lot of time to form a film on a large number of wafers, resulting in high costs. Further, the method described in Patent Document 2 cannot be applied to batch processing in which a plurality of wafers are carried into a film forming apparatus and a plurality of wafers are simultaneously formed.
The present invention has been made in order to eliminate the drawbacks of the prior art, and aims to reduce the variation in frequency temperature characteristics between surface acoustic wave elements formed from the same wafer.

  To achieve the above object, a photomask for forming a surface acoustic wave device according to the present invention is a photomask for exposing a photoresist provided on a piezoelectric substrate, and the piezoelectric substrate is formed on a transparent substrate. A plurality of identical electrode patterns having different orientations corresponding to the interdigital electrodes are provided.

  In the surface acoustic wave element forming photomask according to the present invention, the temperature characteristics of the surface acoustic wave element to be formed differ depending on the position in the piezoelectric substrate. Then, electrode patterns having different directions are exposed. As a result, the effect of substantially changing the in-plane rotation angle of the piezoelectric substrate can be obtained, and variations in frequency temperature characteristics between surface acoustic wave elements formed from the same piezoelectric substrate can be reduced. An accurate surface acoustic wave element can be formed.

  The plurality of electrode patterns may have different directions by a predetermined angular pitch. If the orientations of the plurality of electrode patterns are varied by a predetermined angular pitch, it is possible to easily cope with the correction of the variation of the frequency temperature characteristics using the exposure of the photoresist. The angle pitch can be set arbitrarily, and can be changed by, for example, 0.03 ° or 0.05 °. The smaller the angular pitch, the finer the frequency temperature characteristic can be adjusted, and a more accurate surface acoustic wave element can be formed.

  The plurality of electrode patterns can be formed from a reference pattern and a plurality of inclined patterns inclined symmetrically with respect to the reference pattern. In general, the conductive film for electrodes (metal film) is formed such that the center value of the formed film thickness becomes a design value (target value). Therefore, when the plurality of electrode patterns are constituted by the reference pattern and the plurality of inclined patterns that are inclined symmetrically with respect to the reference pattern, it is possible to easily cope with variations in film thickness and Exposure in consideration of adjustment can be easily performed.

  The method for manufacturing a surface acoustic wave device according to the present invention includes the relationship between the in-plane rotation angle of the piezoelectric substrate and the frequency temperature characteristics of the surface acoustic wave device formed from the piezoelectric substrate, and the conductive film for the electrode. Corresponding to the film forming apparatus for forming a film, the relationship between the frequency temperature characteristic of the surface acoustic wave element formed on the piezoelectric substrate and the position of the piezoelectric substrate is obtained in advance, and a photoresist provided on the piezoelectric substrate is obtained. Based on the relationship between the frequency temperature characteristic obtained in advance and the position of the piezoelectric substrate and the relationship between the frequency temperature characteristic and the in-plane rotation angle of the piezoelectric substrate during exposure, the piezoelectric substrate It is characterized in that electrode patterns having different orientations are exposed in accordance with the positions of.

  In the present invention, the relationship between the frequency temperature characteristic and the position of the piezoelectric substrate and the relationship between the frequency temperature characteristic and the in-plane rotation angle of the piezoelectric substrate are obtained in advance, and the relationship is determined according to the position of the piezoelectric substrate. Thus, the effect of adjusting the in-plane rotation angle of the piezoelectric substrate can be obtained by changing the direction of the electrode pattern to be exposed. For this reason, the variation in the frequency temperature characteristics of the surface acoustic wave elements formed from the same piezoelectric substrate can be reduced, and a highly accurate surface acoustic wave element can be manufactured.

  The relationship between the frequency temperature characteristic and the position of the piezoelectric substrate may be obtained for each film forming condition. For example, the film thickness distribution in the piezoelectric substrate may change depending on the type and size of the target in sputtering, the energy of charged particles, the energy of the laser beam in laser ablation, etc. If the relationship with the position of the piezoelectric substrate is obtained, a surface acoustic wave element with higher accuracy can be obtained.

The relationship between the frequency temperature characteristic and the position of the piezoelectric substrate may be obtained for each photoetching condition for forming the interdigital electrode. According to the inventor's research, the same process is performed depending on the method of etching the conductive film for electrodes, for example, etching with the same etching gas from the beginning to the end, changing the etching gas in the middle, or combining dry etching and wet etching. Even when the film was formed by the film apparatus, it became clear that the distribution of the frequency temperature characteristics of the surface acoustic wave elements on the same piezoelectric substrate was different. Therefore, by obtaining the relationship between the frequency temperature characteristic and the position of the piezoelectric substrate according to the photoetching conditions, a surface acoustic wave element with higher accuracy can be manufactured. The exposure can be performed using any one of the above-described photomasks for forming surface acoustic wave elements. For exposure of electrode patterns with different orientations, a plurality of photomasks may be prepared and used properly. However, by using the above-described photomask for forming a surface acoustic wave element, the photoresist exposure process can be performed easily and quickly. be able to.
The surface acoustic wave device according to the present invention is manufactured by any one of the above-described methods for manufacturing a surface acoustic wave device. Thereby, a highly accurate surface acoustic wave element with small variation in frequency temperature characteristics can be obtained.

  A preferred embodiment of a photomask for forming a surface acoustic wave device, a method for manufacturing a surface acoustic wave device, and a surface acoustic wave device according to the present invention will be described in detail with reference to the accompanying drawings.

  As described in the background art, when a metal film, such as an aluminum film, for forming interdigital electrodes is formed on a disk-shaped quartz crystal wafer which is a piezoelectric substrate, a film thickness distribution is generated in the wafer. The state of the film thickness distribution varies depending on each film forming apparatus, that is, each vapor deposition apparatus and each sputtering apparatus. For this reason, when a surface acoustic wave element is formed from the same in-plane rotated ST-cut quartz wafer, the frequency temperature characteristics of the formed surface acoustic wave element differ depending on the position of the wafer, reflecting the difference in film thickness. come. Therefore, the inventor uses a wafer 20 having a thick film at the central portion 22, a thin film at the intermediate portion 24, and a medium film thickness at the outer peripheral portion 26, as shown in FIG. The relationship between the frequency temperature characteristic and the in-plane rotation angle of the wafer 20 was examined. FIG. 2 shows the result. 2 represents the relative value of the in-plane rotation angle of the wafer 20, and the vertical axis represents the difference (frequency fluctuation) between the maximum frequency and the minimum frequency in the temperature range of 25 ° C. to 85 ° C. as the frequency temperature characteristic. ing. In addition, the frequency fluctuation on the vertical axis is indicated by a relative value based on the minimum frequency fluctuation in each region.

  In the case of the wafer 20 having the film thickness distribution shown in FIG. 5, the surface acoustic wave element formed from the thick central portion 22 has another intermediate portion 24 and an outer peripheral portion as shown by the curve A in FIG. The frequency fluctuation is minimized when the in-plane rotation angle ψ is smaller than that of the surface acoustic wave element formed from H.26. Further, the surface acoustic wave element formed from the thin intermediate portion 24 has the smallest frequency fluctuation at the largest in-plane rotation angle ψ, as shown by the curve C. The surface acoustic wave element formed from the outer peripheral portion 26 having a film thickness intermediate between the two has an in-plane rotation angle ψ between the center portion 22 and the intermediate portion 24 as shown in the curve B. Minimal.

  Therefore, when forming a surface acoustic wave element from the same wafer, the rotation angle (in-plane rotation angle) within the wafer surface can be changed according to the thickness distribution of the electrode metal film formed on the wafer surface. Thus, variation in frequency temperature characteristics can be reduced, and a highly accurate surface acoustic wave element can be obtained. However, when exposing the electrode pattern corresponding to the interdigital electrode provided on the photomask (reticle) using the reduction projection exposure apparatus, the wafer set in the reduction projection exposure apparatus is rotated or the photomask is rotated. I can't. Therefore, as a result of various studies, the inventor forms a plurality of electrode patterns with different orientations on the photomask, and uses different electrode patterns with different orientations according to the position of the wafer when exposing the photoresist provided on the wafer. I thought that I should do it.

  FIG. 1 is an explanatory diagram of a surface acoustic wave element forming mask according to an embodiment of the present invention. In FIG. 1, a photomask 30 is provided with a plurality of (three in the embodiment) electrode patterns 34 (34a to 34c) corresponding to electrodes formed on a surface acoustic wave element on a rectangular transparent substrate 32 such as quartz glass. is there. In the embodiment, the photomask 30 is a photomask (reticle) for a reduction projection exposure apparatus, and each electrode pattern 34 is formed to have a size of about 5 times the original size, for example.

  Each electrode pattern 34 is provided side by side along the longitudinal direction of the transparent substrate 32. In the photomask 30, the electrode pattern 34 is formed from a light-shielding thin film such as chromium (Cr). That is, the photomask 30 of the embodiment is for a positive resist, but may be for a negative resist. Each electrode pattern 34 of the embodiment includes an IDT pattern 36 corresponding to an IDT composed of interdigital electrodes of a surface acoustic wave element, and a pair of reflector (reflecting electrode) patterns provided with the IDT pattern 36 interposed therebetween. 38. Each electrode pattern 34 is formed in a different direction with respect to the transparent substrate 32.

  That is, the electrode pattern 34 a is inclined at an angle α in the counterclockwise direction with respect to the line 44 whose center line 40 a along the longitudinal direction is orthogonal to the long side 42 of the transparent substrate 32. In the electrode pattern 34 b, the center line 40 b along the longitudinal direction is orthogonal to the long side 42. On the other hand, in the electrode pattern 34 c, the center line 40 c along the longitudinal direction is inclined by an angle β in the clockwise direction with respect to the line 44 orthogonal to the long side 42 of the transparent substrate 32. In the embodiment, the electrode pattern 34b is a reference pattern, and the electrode patterns 34a and 34c are inclined patterns that are symmetrically inclined with respect to the electrode pattern 34b. That is, the inclination angle α of the electrode pattern 34a and the inclination angle β of the electrode pattern 34c are the same, for example, 0.05 °. Thereby, the direction of each electrode pattern 34 is different by a predetermined angle pitch.

  However, the electrode patterns 34 are formed in the same direction except for the direction in which they are formed. That is, the electrode patterns 34a to 34c are formed in the same logarithm, formation pitch, width, and length of the electrode finger patterns 46 constituting the IDT pattern 36. Similarly, the reflector pattern 38 of each electrode pattern 34 is formed with the same number, conductor pitch, width, and length of the conductor strips 48.

  A method of manufacturing a surface acoustic wave device using the photomask 30 thus configured is performed as follows. First, a piezoelectric wafer, which is a piezoelectric substrate cut out at a predetermined cut angle (in the case of the embodiment, in-plane rotating ST-cut quartz wafer) is cleaned, and as shown in step 50 of FIG. A conductive film for an electrode for forming is formed. The conductive film for electrodes is a metal film such as aluminum (Al) or aluminum alloy. The conductive film is formed by vacuum deposition or sputtering using a deposition apparatus such as a vacuum deposition apparatus or a sputtering apparatus so that the average film thickness becomes a design value. If the conductive film is formed to a predetermined thickness, a photoresist is applied on the conductive film and solidified (step 52).

  Thereafter, the photoresist is exposed using the photomask 30 shown in FIG. 1 (step 54). This exposure process corresponds to the relationship between the in-plane rotation angle of the piezoelectric substrate and the frequency temperature characteristics of the surface acoustic wave element formed from the piezoelectric substrate, and the film forming apparatus for forming the electrode conductive film. The relationship between the frequency temperature characteristic of the surface acoustic wave element formed on the piezoelectric substrate and the position of the piezoelectric substrate is obtained in advance. Then, based on the frequency temperature characteristic data, the photoresist is exposed using the electrode patterns 34a to 34c of the photomask 30 properly.

  For example, the piezoelectric substrate is an in-plane rotated ST-cut quartz plate with Euler angle display (0 °, 123 °, 40 °), and the film thickness of the conductive film has a distribution as shown in FIG. If so, exposure is performed as follows. Note that the electrode conductive film of the wafer 20 is formed so that the outer peripheral portion 26 of the wafer 20 has a target film thickness (designed film thickness). In this case, as described above, the central portion 22 of the wafer 20 is thick. The central portion 22 has the smallest frequency fluctuation at 25 ° C. to 85 ° C., which is the frequency temperature characteristic, in the place where the in-plane rotation angle ψ is the smallest than other portions. Therefore, when exposing the central portion 22 of the wafer 20 with the photomask 30, the electrode pattern 34a is used. Thereby, the central portion 22 of the wafer 20 exposes the electrode pattern by rotating the wafer 20 clockwise by an angle α, that is, reducing the in-plane rotation ψ by an angle α (in the embodiment, 0.05 °). It will be done. In other words, in the case of the embodiment, the central portion 22 has the same effect as when an in-plane rotated ST-cut quartz plate with Euler angle display (0 °, 123 °, 39.95 °) is used.

  Further, the intermediate portion 24 of the wafer 20 with the thin conductive film is exposed using the electrode pattern 34 c of the photomask 30. Thus, the electrode 20 is exposed by rotating the wafer 20 counterclockwise by the angle β, that is, increasing the in-plane rotation angle ψ by the angle β (in the embodiment, 0.05 °). For this reason, the intermediate portion 24 of the wafer 20 can obtain the same effect as when the in-plane rotated ST-cut quartz plate of Euler angle display (0 °, 123 °, 40.05 °) is used. Then, the outer peripheral portion 26 of the wafer 20 having the target film thickness is exposed using an electrode pattern 34b which is a standard pattern of the photomask 30. Thereby, the outer peripheral part 26 exposed the electrode pattern to the in-plane rotation ST-cut quartz plate of (0 °, 123 °, 40.00 °). The order of exposure may be performed first in any part, or in the horizontal direction or the vertical direction of the wafer 20.

  After the exposure of the photoresist in this manner, as shown in step 56, the photoresist is developed and patterned to leave a portion of the photoresist corresponding to the electrode pattern 34. Thereafter, the electrode conductive film is etched using the patterned photoresist as a mask to form a surface acoustic wave element having an IDT and a reflector on the wafer 20 (step 58). Next, the frequency temperature characteristic (frequency fluctuation at 20 ° C. to 85 ° C.) of the surface acoustic wave element formed on the wafer 20 is measured (step 60). Further, based on the measured frequency temperature characteristic, the frequency temperature characteristic data used for the exposure of the photoresist at this time is corrected (step 62). Then, the next exposure of the photoresist is performed by properly using the electrode patterns 34a to 34c of the photomask 30 by using the data of the corrected frequency temperature characteristics reflecting the result of the current exposure. The wafer 20 on which the surface acoustic wave elements are formed is transferred to the next dicing step and divided into individual surface acoustic wave elements.

  As described above, in the embodiment, the relationship between the in-plane rotation angle of the piezoelectric substrate and the frequency temperature characteristic of the surface acoustic wave element formed from the piezoelectric substrate, and the film forming apparatus for forming the electrode conductive film Accordingly, the relationship between the frequency temperature characteristic of the surface acoustic wave element formed on the piezoelectric substrate and the position of the piezoelectric substrate is determined in advance, and the orientation is determined according to the position of the piezoelectric substrate based on these relationships. By performing exposure using different electrode patterns, it is possible to reduce the variation in the frequency temperature characteristics of the surface acoustic wave elements formed on the piezoelectric substrate, and it is possible to manufacture a highly accurate surface acoustic wave element.

  The photomask 30 according to the embodiment can easily expose the electrode patterns having different directions according to the position of the piezoelectric substrate by forming a plurality of electrode patterns having different directions on the transparent substrate 32. Moreover, since the orientation of the electrode patterns 34 is different at a predetermined angular pitch, the photomask 30 can be easily exposed to correct the variation in frequency temperature characteristics. Furthermore, since the photomask 30 of the embodiment includes the electrode pattern 34b serving as a reference pattern and the electrode patterns 34a and 34c that are inclined patterns inclined symmetrically with respect to the electrode pattern 34b, It is possible to easily cope with variations in thickness.

  In addition, the said embodiment is 1 aspect of this invention, and is not limited to this. For example, in the above-described embodiment, the case where three electrode patterns are formed on the transparent substrate 32 has been described. However, any number (for example, four, five, etc.) of electrode patterns having different directions may be formed. In the above embodiment, the case where the orientations of the electrode patterns 34a to 34c are different by 0.05 ° has been described. However, the angle pitch is arbitrarily set, such as 0.03 ° or 0.01 °. be able to. When the angular pitch is reduced, finer frequency temperature characteristics can be adjusted, and a surface acoustic wave element with higher accuracy can be manufactured. In the above embodiment, the case where the plurality of electrode patterns are formed in parallel in the longitudinal direction of the transparent substrate 32 has been described. However, these patterns may be formed in series in the longitudinal direction of the transparent substrate 32. However, they may be arranged in a matrix. Depending on the state of film thickness distribution, the direction of each electrode pattern 34 may be different from the equiangular pitch.

  In the above embodiment, the case where the relationship between the position of the piezoelectric substrate and the temperature characteristics of the surface acoustic wave element is simply determined corresponding to the film forming apparatus has been described. The relationship between the added position of the piezoelectric substrate and the frequency temperature characteristic may be obtained in advance. Furthermore, according to the inventor's research, even when the film is formed by the same film forming apparatus, the conductive film is etched from the beginning to the end by the same etching gas, for example, by the same etching gas, or the etching gas is stopped in the middle. It has been found that the film thickness distribution (frequency temperature characteristic distribution) differs depending on whether it is changed by (1) or by combining dry etching and wet etching. Therefore, it is desirable to obtain the relationship between the position of the piezoelectric substrate in consideration of the photoetching conditions and the frequency temperature characteristics of the surface acoustic wave. In the above-described embodiment, the case where the piezoelectric substrate is an in-plane rotation ST-cut quartz plate has been described. However, the piezoelectric substrate is not limited to this, and the in-plane rotation angle has a frequency-temperature characteristic of the surface acoustic wave. The present invention can be applied to all the piezoelectric substrates that have an influence. Furthermore, in the above-described embodiment, the surface acoustic wave element for a resonator in which one IDT is provided between a pair of reflectors has been described, but the elasticity for a filter in which a plurality of IDTs are provided between the reflectors. The present invention can also be applied to the manufacture of surface acoustic wave elements and transversal surface acoustic wave elements.

It is a top view of the photomask which concerns on embodiment of this invention. It is a figure which shows the relationship between the in-plane rotation angle and the frequency temperature characteristic in the position of the piezoelectric material board | substrate which formed the electrically conductive film. It is a flowchart explaining the principal part of the manufacturing process of the surface acoustic wave element concerning embodiment of this invention. It is a figure explaining the surface acoustic wave element which consists of an in-plane rotation ST cut quartz plate. It is a figure explaining an example of the film thickness distribution of the electrically conductive film for electrodes formed in the piezoelectric material board | substrate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ......... ST cut quartz plate, 14 ......... Surface acoustic wave element, 20 ..... Wafer (piezoelectric substrate), 30 ..... Photomask, 32 .... Transparent substrate, 34a-34c ..... Electrode Pattern, 36 ... IDT pattern, 38 ... Reflector pattern.

Claims (8)

A photomask for exposing a photoresist provided on a piezoelectric substrate,
A surface acoustic wave element forming photomask, wherein a plurality of identical electrode patterns having different orientations corresponding to interdigital electrodes formed on the piezoelectric substrate are provided on a transparent substrate. The photomask for forming a surface acoustic wave device according to claim 1,
The surface acoustic wave element forming photomask, wherein the plurality of electrode patterns have different directions by a predetermined angular pitch. The photomask for forming a surface acoustic wave element according to claim 1 or 2,
The surface acoustic wave element forming photomask, wherein the plurality of electrode patterns include a reference pattern and a plurality of inclined patterns inclined symmetrically with respect to the reference pattern. The relationship between the in-plane rotation angle of the piezoelectric substrate and the frequency temperature characteristics of the surface acoustic wave device formed from the piezoelectric substrate,
In correspondence with the film forming apparatus for forming the electrode conductive film, the relationship between the frequency temperature characteristics of the surface acoustic wave element formed on the piezoelectric substrate and the position of the piezoelectric substrate is obtained in advance.
When exposing the photoresist provided on the piezoelectric substrate, the relationship between the frequency temperature characteristic obtained in advance and the position of the piezoelectric substrate, and the frequency temperature characteristic and the in-plane rotation angle of the piezoelectric substrate, Based on the relationship, according to the position of the piezoelectric substrate, the electrode patterns having different orientations are exposed.
A method of manufacturing a surface acoustic wave device. In the manufacturing method of the surface acoustic wave device according to claim 4,
A method of manufacturing a surface acoustic wave device, wherein the relationship between the frequency temperature characteristic and the position of the piezoelectric substrate is obtained for each film forming condition. In the manufacturing method of the surface acoustic wave element according to claim 4 or 5,
A method of manufacturing a surface acoustic wave device, wherein the relationship between the frequency temperature characteristic and the position of the piezoelectric substrate is obtained for each photoetching condition for forming the interdigital electrode. The method for producing a surface acoustic wave according to any one of claims 4 to 6,
4. The method of manufacturing a surface acoustic wave device according to claim 1, wherein the exposure is performed using the photomask for forming a surface acoustic wave device according to claim 1.   A surface acoustic wave device manufactured by the method for manufacturing a surface acoustic wave device according to claim 4.

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