JP2002190715A - Apparatus for manufacturing surface acoustic wave device and method for manufacturing surface acoustic wave device - Google Patents

Abstract

(57) [Problem] To provide an apparatus for manufacturing a surface acoustic wave device in which the adhesion of an electrode film is good and the piezoelectric substrate does not crack. A vacuum chamber (7) and a vacuum chamber (7)
A stage 1 on which the piezoelectric substrate is placed, and an insulating guide ring 4 extending vertically from the surface of the stage 1 on which the piezoelectric substrate is placed and having an inner diameter larger than the diameter of the piezoelectric substrate; A surface acoustic wave device manufacturing apparatus including a target disposed above a stage, wherein a counterbore (step) having a diameter smaller than the diameter of the piezoelectric substrate is formed on the surface of the stage, and a counterbore is formed. One or more gas introduction holes 3 are formed in the surface 12 of the stage 1 inside the stage 2. While floating the piezoelectric substrate from the stage 1, the target 14 is sputtered to form an electrode film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a surface acoustic wave device and an apparatus for manufacturing a surface acoustic wave device.
The present invention relates to a method of manufacturing a highly reliable surface acoustic wave device having a high yield by forming a metal film on a piezoelectric substrate while floating and cooling the piezoelectric substrate, and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art A surface acoustic wave device (SAW (SuW) using a surface acoustic wave in which energy is concentrated only on the surface of a crystal substrate.
rface Acoustic Wave) devices) have a propagation speed of ^10-5 times slower than electromagnetic waves and can be miniaturized, so in recent years they have been applied to filters, vibrators, delay elements, etc. It has been used in a wide range of fields such as communication devices.

A surface acoustic wave device has a piezoelectric substrate and two interdigitated metal electrodes such as aluminum (Al) formed on the piezoelectric substrate. Conventionally, a surface acoustic wave device is manufactured by uniformly forming an electrode film on a piezoelectric substrate and patterning the electrode film into a predetermined shape using a lithography technique and an etching technique. In addition, a sputtering method is mainly used for forming an electrode film because the film formation is easy, the film thickness is easy to control, the apparatus itself is easy to handle, and the film can be formed at low cost. ing.

FIG. 4 is a sectional view showing the structure of a conventional sputtering apparatus. A support 6 is provided at the center of the inside of the vacuum vessel 57.
The stage 51 is fixed via the reference numeral 0, and a target 64 made of a metal such as Al is arranged above the stage 51. The vacuum vessel 57 is provided with a vacuum pump 58 for generating and maintaining a vacuum atmosphere necessary for sputtering, and a gas introduction hole 53 for introducing a sputtering gas.
By applying a high-frequency power and a predetermined static voltage between the target 64 and the stage 51, Al ions sputtered from the target 64 are deposited on the piezoelectric substrate 55 mounted on the stage 51, and the electrode film is formed. A film can be formed.

[0005]

However, many piezoelectric substrates used in a surface acoustic wave device have a strong pyroelectricity (a property of generating an electric charge when a temperature change is given). Therefore, when forming an electrode film on a piezoelectric substrate, it is necessary to maintain the temperature of the piezoelectric substrate in an appropriate temperature range.

That is, when an electrode film is formed on a piezoelectric substrate using a sputtering apparatus having no means for cooling the piezoelectric substrate, the temperature of the piezoelectric substrate rises as the film is formed, and static electricity is generated in the piezoelectric substrate. Discharge occurs. Due to the static electricity and electric discharge, cracks and chips in the piezoelectric substrate, cracks in the electrode film, and the like occur. On the other hand, when the electrode film is formed while cooling the piezoelectric substrate using a sputtering apparatus having a means for cooling the piezoelectric substrate, cracking, chipping, cracking of the electrode film and the like of the piezoelectric substrate no longer occur,
If the temperature of the piezoelectric substrate is excessively lowered, another problem such as peeling of the electrode film or reduction in the adhesion between the electrode film and the piezoelectric substrate occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and has as its object to provide an elastic surface which has good adhesion of an electrode film and does not cause cracking of a piezoelectric substrate. An object of the present invention is to provide a method for manufacturing a wave device and a device for manufacturing a surface acoustic wave device.

Another object of the present invention is to improve the yield,
An object of the present invention is to provide a method of manufacturing a surface acoustic wave device with high reliability and an apparatus for manufacturing a surface acoustic wave device.

[0009]

Means for Solving the Problems To achieve the above object, a first feature of the present invention is that a vacuum chamber, a stage disposed in the vacuum chamber, on which a piezoelectric substrate is mounted, and a piezoelectric substrate are provided. An apparatus for manufacturing a surface acoustic wave device, comprising: an insulating guide ring extending vertically from a surface of a stage to be mounted and having an inner diameter larger than a diameter of a piezoelectric substrate; and a target disposed above the stage. A counterbore (step) having a diameter smaller than the diameter of the piezoelectric substrate is formed on the surface of the stage, and one or two or more gas introduction holes are formed on the surface of the stage inside the counterbore. That is. Here, the target is made of the same material as the electrode film formed on the piezoelectric substrate, and can apply high-frequency power and a predetermined static voltage between the target and the stage.

The sputter gas introduced from the gas introduction hole is introduced into a recess (groove) of the stage formed by a counterbore (step). The sputter gas accumulated in the concave portions (grooves) applies a uniform pressure to the piezoelectric substrate and causes the piezoelectric substrate to float from the stage. The floating state of the piezoelectric substrate is maintained by the insulating guide ring disposed outside the piezoelectric substrate. In this floating state of the piezoelectric substrate, the electrode film is formed by sputtering the target.

According to the first aspect of the present invention, sputtering is performed by continuously blowing a sputtering gas on the back surface of the piezoelectric substrate to maintain the floating state of the piezoelectric substrate.
The sputtering gas cools the piezoelectric substrate, and the temperature rise of the piezoelectric substrate due to sputtering can be suppressed. At the same time, by causing the piezoelectric substrate to float sufficiently high that no discharge occurs between the piezoelectric substrate and the stage, it is possible to prevent the piezoelectric substrate from being discharged.

In order to float the piezoelectric substrate to a height at which discharge can be prevented and to sufficiently cool the piezoelectric substrate, the inner diameter of the insulating guide ring is 1 to 3 mm larger than the diameter of the piezoelectric substrate.
It is desirable only to be large.

A second feature of the present invention is that (a) a piezoelectric substrate is placed in a vacuum chamber and is mounted on the surface of a stage on which a counterbore (step) having a diameter smaller than the diameter of the piezoelectric substrate is formed. (B) evacuation of the vacuum chamber to form a predetermined vacuum atmosphere necessary for sputtering, and (c) a step formed on the surface of the stage inside the counterbore (step). A third step of continuously introducing a predetermined flow rate of a sputtering gas from one or more gas introduction holes into the vacuum chamber;
(D) A fourth step of forming an electrode film on the piezoelectric substrate by sputtering a target placed above the stage while continuously introducing a predetermined flow rate of a sputtering gas to float the piezoelectric substrate from the stage. And a step of manufacturing the surface acoustic wave device. Here, in the first step, an insulating guide ring that is extended in the vertical direction and has an inner diameter larger than the diameter of the piezoelectric substrate is disposed on the surface of the stage, and the piezoelectric substrate is disposed in the insulating guide ring. . In the fourth step, the floating state of the piezoelectric substrate is maintained by the insulating guide ring.

According to a second feature of the present invention, in a method of manufacturing a surface acoustic wave device comprising a piezoelectric substrate and electrodes formed on the piezoelectric substrate, an electrode film to be an electrode is formed by a sputtering method. In doing so, the piezoelectric substrate can be floated by ejecting a sputtering gas toward the back surface of the piezoelectric substrate, and the piezoelectric substrate can be cooled.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the dimensional relationships, ratios, and the like between the height and the width are different from actual ones.

FIG. 1A is a sectional view showing a configuration of a manufacturing apparatus (sputtering apparatus) for a surface acoustic wave device according to an embodiment of the present invention. As shown in FIG. 1A, a sputtering apparatus according to an embodiment of the present invention includes a vacuum chamber 7 capable of maintaining the inside in a vacuum atmosphere,
Vacuum evacuation means such as a vacuum pump 8 for evacuating the inside of the vacuum chamber 7 and maintaining a vacuum atmosphere necessary for performing sputtering, the stage 1 disposed inside the vacuum chamber 7, and above the stage 1 Placed in
At least a target 14 to which high-frequency power and a predetermined static voltage can be applied to the stage 1.

A counterbore (step) 2 having a diameter smaller than that of the piezoelectric substrate is formed on the surface of the stage 1 on which the wafer-shaped piezoelectric substrate is mounted. It is formed one step lower than the outside. Therefore, the stage 1 in FIG. 1A has a concave cross-sectional shape. An insulating guide ring 4 extending in a direction perpendicular to the upper surface 13 is arranged on a portion (hereinafter referred to as an “upper surface”) 13 of the surface of the stage 1 outside the counterbore 2. The insulating guide ring 4 is made of an insulating material such as Teflon (registered trademark), and has an inner diameter larger than the diameter of the piezoelectric substrate. A predetermined number of gas introduction holes 3 are formed in a portion (hereinafter referred to as a “bottom surface”) 12 of the surface of the stage 1 inside the counterbore 2. The diameter of the gas introduction hole 3 on the bottom surface 12 is about 1 mm, and the gas introduction hole 3 is integrated into one inside the stage 1, and is outside the vacuum chamber 7 via a gas pipe 11 arranged in a support 10. Has been drawn to. The gas pipe 11 is connected to gas flow adjusting means such as the gas introduction valve 9.

FIG. 1B is a plan view showing the arrangement of the surface of the stage 1 and the insulating guide ring 4 shown in FIG. 1A. An insulating guide ring 4 is disposed inside the outer periphery of the stage 1, and a counterbore 2 is formed inside the insulating guide ring 4. The outer periphery of the stage 1, the insulating guide ring 4, and the counterbore 2 have a concentric plane shape. Inside the counterbore 2, that is, on the bottom surface 12 of the stage 1, one at the center,
Eight gas introduction holes are formed at equal distances and equal intervals from the center, that is, a total of 9 gas introduction holes.

Next, the operation of the sputtering apparatus shown in FIGS. 1A and 1B will be described with reference to FIGS. 2A, 2B, and 3. FIG.

(A) First, in the first step, FIG.
As shown in (a), a wafer-shaped piezoelectric substrate 5 is placed in an insulating guide ring 4 on the surface of the stage 1. At this time,
Since the diameter of the piezoelectric substrate 5, the inner diameter of the insulating guide ring 4, and the diameter of the counterbore 2 have a relationship of “inner diameter of the insulating guide ring 4> diameter of the piezoelectric substrate 5> and diameter of the counterbore 2, Is placed with its outermost peripheral portion in contact with the upper surface 13 of the stage 1. In other words, the concave portion (groove) of the stage 1 is closed by the piezoelectric substrate 5. FIG. 2B is a plan view showing an arrangement relationship between the insulating guide ring 4 and the piezoelectric substrate 5 on the surface of the stage 1. The outer periphery of the piezoelectric substrate 5 is arranged inside the insulating guide ring 4, and the counterbore indicated by the dotted line 2 is arranged inside the outer periphery of the piezoelectric substrate 5.

(B) Next, in a second step, the vacuum pump 8 is operated to evacuate the vacuum chamber 7 to form a predetermined vacuum atmosphere required for sputtering.
Then, the gas introduction valve 9 is opened, and a predetermined flow rate of the sputtering gas is introduced into the vacuum chamber 7 from the gas introduction hole 3. FIG. 3 is a cross-sectional view showing a state where the sputtering gas is continuously introduced. Arrow 6 in FIG. 3 indicates the flow of the sputtering gas. The sputtering gas is introduced from the gas introduction hole 3 into the recess (groove) of the stage 1. The sputtering gas accumulated in the concave portion (groove) of the stage 1 in a vacuum atmosphere gives a uniform pressure to the piezoelectric substrate 5. When the pressure due to the sputtering gas increases and becomes larger than the weight of the piezoelectric substrate 5, the outermost peripheral portion of the piezoelectric substrate 5 moves away from the upper surface 13 of the stage 1, and the sputtering gas passes through the gap between the piezoelectric substrate 5 and the upper surface 13 of the stage 1. And escapes above the piezoelectric substrate 5 through the gap between the piezoelectric substrate 5 and the insulating guide ring 4. Since the insulating guide ring 4 is arranged outside the piezoelectric substrate 5, the piezoelectric substrate 5 does not largely move in the lateral direction. Therefore,
By continuously introducing a predetermined flow rate of sputtering gas,
The state where the outermost peripheral portion of the piezoelectric substrate 5 is separated from the upper surface 13 of the stage 1, that is, the state where the piezoelectric substrate 5 floats from the stage 1, can be maintained.

(C) Next, in a third step, a predetermined high-frequency power is applied between the stage 1 and the target 14 while maintaining the state in which the piezoelectric substrate 5 is floating. At the same time, a positive static voltage is applied to the target 14 with respect to the stage 1. Plasma is generated between the stage 1 and the target 14 by the sputter gas that has escaped above the piezoelectric substrate 5. Metal ions such as Al ions are sputtered from the surface of the target 14 by the plasma, and the metal ions adhere to the piezoelectric substrate 5 by an electrostatic field from the target 14 toward the stage 1. That is,
A sputtered film is deposited on the surface of the piezoelectric substrate 1. Through the steps described above, an electrode film can be formed on the piezoelectric substrate 5.

According to the embodiment of the present invention, the concave portion (groove)
By continuously introducing a sputtering gas into the substrate and performing sputtering (second step) while floating the wafer-shaped piezoelectric substrate from the stage 1 (second step).
The sputtering gas cools the piezoelectric substrate 5 and suppresses a temperature rise of the piezoelectric substrate 5 due to sputtering. Therefore, the temperature of the piezoelectric substrate during sputtering can be maintained at an appropriate temperature by an inexpensive and simple method. At the same time, by causing the piezoelectric substrate 5 to float sufficiently high that no discharge occurs between the piezoelectric substrate 5 and the stage 1, it is possible to prevent the piezoelectric substrate 5 from generating a discharge. Further, the sputtered film (electrode film) is prevented from adhering to the side and back surfaces of the piezoelectric substrate 5 and the side surfaces of the insulating guide ring 4 due to the pressure of the sputter gas passing through the gap between the insulating guide ring 4 and the piezoelectric substrate 5. be able to. That is, a sputtered film is formed only on the surface of the piezoelectric substrate 5 on which an electrode film is to be formed, and adhesion to other unnecessary portions can be prevented.

The cooling capacity of the piezoelectric substrate and the distance between the floating piezoelectric substrate 5 and the stage 1 can be adjusted by controlling the flow rate of the sputtering gas. Therefore,
The temperature of the piezoelectric substrate 5 can be maintained in a range suitable for the sputtering process, and at the same time, the piezoelectric substrate 5 can be floated to such a height that no discharge occurs. In the embodiment of the present invention, it was possible to prevent the occurrence of electric discharge by floating 2 mm or more.

Further, for each wafer size of the piezoelectric substrate 5,
By preparing different stages 1 such as the diameter of the counterbore 2, the inner diameter of the insulating guide ring 4, the number of the gas introduction holes 3, and the like, the structure is made detachable from the support 10 and the gas pipe 11.
A sputtering apparatus corresponding to each wafer size can be obtained. In the embodiment of the present invention, stage 1
In order to maintain the pressure of the sputtering gas in the concave portions (grooves), it is desirable that the inner diameter of the insulating guide ring 4 is 1 to 3 mm larger than the diameter of the piezoelectric substrate 5. When the difference between the inner diameter of the insulating guide ring 4 and the diameter of the piezoelectric substrate 5 is 1 mm or less, if a small amount of sputtering gas is introduced, the piezoelectric substrate 5 can be floated to a height at which discharge can be prevented. Sufficient cooling could not be performed. Therefore, the temperature of the piezoelectric substrate 5 was too high, and cracks occurred. On the other hand, when the difference between the inner diameter of the insulating guide ring 4 and the diameter of the piezoelectric substrate 5 is 3 mm or more, the pressure of the sputter gas in the concave portion (groove) of the stage 1 escapes, and the piezoelectric substrate 5 floats to a height where discharge can be prevented. I couldn't let it. Conversely, if the piezoelectric substrate 5 is floated to a height at which discharge can be prevented by introducing more sputter gas than necessary,
Is excessively cooled, and the electrode film is peeled off, or the adhesion between the electrode film and the piezoelectric substrate 5 is reduced.

[0026]

As described above, according to the present invention, a method for manufacturing a surface acoustic wave device and a device for manufacturing a surface acoustic wave device that have good adhesion of an electrode film and do not cause cracking of a piezoelectric substrate or the like are provided. Can be provided.

Further, according to the present invention, it is possible to provide a method for manufacturing a surface acoustic wave device and a device for manufacturing a surface acoustic wave device with high yield and high reliability.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a configuration of a sputtering apparatus according to an embodiment of the present invention. FIG. 1B is a plan view showing the arrangement of the surface of the stage 1 and the insulating guide ring 4 shown in FIG.

FIG. 2A is a cross-sectional view for explaining the operation of the sputtering apparatus shown in FIGS. 1A and 1B (part 1). FIG. 2B is a plan view showing the arrangement of the surface of the stage 1, the insulating guide ring 4, and the piezoelectric substrate 5 shown in FIG.

FIG. 3 is a cross-sectional view for explaining the operation of the sputtering apparatus shown in FIGS. 1A and 1B (part 2).

FIG. 4 is a cross-sectional view illustrating a configuration of a sputtering apparatus according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stage 2 Counterbore 3 Gas introduction hole 4 Insulation guide ring 5 Piezoelectric substrate 6 Gas flow 7 Vacuum chamber 8 Vacuum pump 9 Gas introduction valve 10 Prop 11 Gas pipe 12 Bottom 13 Top

Claims (3)

[Claims] A vacuum chamber; a stage disposed in the vacuum chamber, on which the piezoelectric substrate is mounted; and a stage extending vertically from a surface of the stage on which the piezoelectric substrate is mounted, and An insulating guide ring having an inner diameter larger than the diameter, and a target disposed above the stage, wherein a counterbore having a diameter smaller than the diameter of the piezoelectric substrate is formed on the surface of the stage, and An apparatus for manufacturing a surface acoustic wave device, wherein one or two or more gas introduction holes are formed on the surface of the stage inside. 2. The apparatus according to claim 1, wherein an inner diameter of the insulating guide ring is larger than a diameter of the piezoelectric substrate by 1 to 3 mm. 3. An insulation guide having a piezoelectric substrate disposed in a vacuum chamber and having an inner diameter larger than the diameter of the piezoelectric substrate on the surface of a stage on which a counterbore having a diameter smaller than the diameter of the piezoelectric substrate is formed. A first step of mounting in a ring, a second step of evacuating the vacuum chamber to form a predetermined vacuum atmosphere necessary for sputtering, and a step formed on the surface of the stage inside the counterbore. A third method for continuously introducing a predetermined flow rate of a sputtering gas into the vacuum chamber from one or more gas introduction holes;
Step, while continuously introducing the sputtering gas at the predetermined flow rate and floating the piezoelectric substrate from the stage, sputtering a target disposed above the stage to form an electrode film on the piezoelectric substrate. And a fourth step of forming a film.