TWI784981B - Method of forming piezoelectric crystal film and tray for forming piezoelectric crystal film - Google Patents

Abstract

Provided is a method of forming the piezoelectric crystal film having a step of disposing a substrate on a tray which is formed of ceramic and the diameter of the outer edge portion of the portion of the tray where the base material on the side to be placed with the substrate is exposed is 1.05 times or more and 15 times or less of the diameter of the substrate, a step of disposing a substrate together with the tray so as to face a target containing materials of a piezoelectric material arranged in a film formation space, a step of heating the substrate from the tray side, a step of applying a voltage to the target, and a step of forming a piezoelectric crystal film on the substrate.

Description

Method for forming piezoelectric crystal film and disk for forming piezoelectric crystal film

The present invention relates to a method for forming a piezoelectric crystal film and a disk for forming a piezoelectric crystal film.

Conventionally, methods for forming a piezoelectric crystal film are widely known. A film-forming method of such a piezoelectric crystal film is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-060658 and Japanese Patent No. 5747041.

In the aforementioned Japanese Patent Application Laid-Open No. 10-060658, a film-forming method of a piezoelectric crystal film has been disclosed. The substrate is placed on a holder so as to face a target in the film-forming space. The heater heats the substrate mounted on the holder, and applies a voltage to the target to form a piezoelectric crystal film on the substrate. In the method for forming a piezoelectric crystal film described in Japanese Patent Application Laid-Open No. 10-060658, the substrate is directly placed on a holder fixed in a film-forming space.

In addition, the above-mentioned Japanese Patent No. 5747041 discloses a method for forming a piezoelectric crystal film, in which a substrate is placed on a substrate holder so as to face a target in the film formation space, The heating unit on the seat side heats the substrate placed on the substrate holding seat, applies a voltage to the target, and forms a piezoelectric crystal film on the substrate. In the method for forming a piezoelectric crystal film described in Japanese Patent No. 5747041, a substrate is directly placed on a substrate holder fixed in a film forming space.

However, in the method for forming a piezoelectric crystal film in the aforementioned Japanese Patent Laid-Open No. 10-060658 and Japanese Patent No. 5747041, since the substrate is directly placed on a holder (substrate holder) fixed in the film-forming space, , When the size of the substrate is larger than that of the holder, the heat transferred to the substrate is different between the part in contact with the holder and the part not in contact with the holder, and the temperature of the substrate is not stable. In addition, if the size of the substrate is smaller than that of the holder, the heat will be dissipated by radiation from the portion of the holder exposed to the substrate, resulting in loss of heat from the substrate through the holder. Therefore, temperature control of the substrate becomes difficult. As a result, the temperature of the substrate becomes uneven, resulting in uneven composition of the piezoelectric crystal film. Therefore, there is a problem that it is difficult to stably form a piezoelectric crystal film with good film quality on a substrate.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a method for forming a piezoelectric crystal film and a piezoelectric crystal film capable of stably forming a piezoelectric crystal film with good film quality on a substrate. Film-forming disk.

In order to solve the above-mentioned problems, the inventors of the present application made intensive research and found that the diameter of the outer edge of the exposed part of the base material on the side surface of the base material that is made of ceramics and carries the base plate is 1.05 times the diameter of the base plate. When the piezoelectric crystal film is formed on the substrate with a disk of 1.15 times or less, a piezoelectric crystal film with good film quality can be stably formed on the substrate. That is, the film-forming method of the piezoelectric crystal film according to the first aspect of the present invention comprises: disposing the substrate on the surface of the substrate on the side of the substrate which is made of ceramics and the diameter of the outer edge part is exposed. A step in which the diameter of the substrate is at least 1.05 times and not more than 1.15 times the disk; a step of arranging the substrate and the disk so as to face a target of a material including a piezoelectric body arranged in the film formation space; a step of heating the substrate from the disk side ; a step of applying a voltage to the target; and a step of forming a piezoelectric crystal film on the substrate.

In the film-forming method of the piezoelectric crystal film according to the first aspect of the present invention, with the above-mentioned configuration, the substrate and the disk can be arranged in the film-forming space, so the disk can be selected according to the size of the substrate, and the piezoelectric body can be formed The crystal film is formed on the substrate. That is, the substrate is disposed on a disc in which the diameter of the outer edge of the exposed portion of the base material on the side surface carrying the substrate is 1.05 to 1.15 times the diameter of the substrate, and the piezoelectric crystal film is formed on the substrate. . Thereby, the substrate can be heated while the entire back surface of the substrate is in contact with the disk, and the temperature of the substrate can be stabilized. Also, by forming the diameter of the outer edge of the exposed portion of the substrate on the side surface of the carrying substrate to be 1.15 times or less the diameter of the substrate, the exposed portion of the substrate of the disc can be suppressed from becoming too large. An increase in the amount of heat dissipation due to radiant heat from the exposed portion of the base material of the disk can be suppressed. Thereby, the heat loss of the substrate through the disk can be suppressed, and the temperature unevenness of the substrate can be reduced, so as to reduce the unevenness of the film quality in the surface of the substrate. In addition, since temperature control can be easily performed, a piezoelectric crystal film having good film quality can be stably formed on the substrate. In addition, the thermal capacity of the disk can keep the substrate warm, and the rapid cooling of the substrate after film formation can be suppressed, thereby suppressing the deterioration of the film quality of the piezoelectric crystal film. Thereby, the temperature unevenness of the substrate can also be reduced, thereby reducing the unevenness of the film quality in the substrate surface. In addition, by forming the diameter of the outer edge of the exposed portion of the substrate on the side surface of the carrying substrate to be at least 1.05 times the diameter of the substrate, the exposed portion of the substrate can be easily formed in accordance with the diameter of the substrate.

In the film-forming method of the piezoelectric crystal film according to the first aspect, preferably, in the step of arranging the substrate on the disk, the substrate is positioned by the convex positioning portion formed on the surface of the disk on the side where the substrate is placed. Position and place the substrate on the tray. According to the above configuration, since the entire back surface of the substrate can be easily disposed on the exposed portion of the disk base material, heat can be uniformly transferred to the substrate through the disk base material. In addition, when the disc on which the substrate is placed is moved, deviation of the substrate from the disc can be suppressed by the positioning portion.

In this case, the positioning portion of the disk is preferably formed along the outer periphery of the disk. According to the above configuration, since the convex positioning portion can be arranged on the outer periphery of the disk, it is possible to increase the heat capacity of the outer periphery of the disk. Thereby, the temperature on the outer peripheral side of the substrate can be suppressed from being lower than that on the central side, and the piezoelectric crystal film can be formed stably.

In the film-forming method of the piezoelectric crystal film according to the first aspect, preferably, in the disk, the diameter of the exposed portion of the base material on the side of the disk carrying the substrate is 1.05 times the diameter of the substrate. In a manner of 1.15 times or less, the portion of the carrier substrate other than the substrate mounting region of the carrier substrate side surface is covered with a metal. According to the above configuration, since heat radiation from the disk can be suppressed by the metal coating, the piezoelectric crystal film can be stably formed even on a substrate having a diameter less than 1/1.15 times the diameter of the disk.

In the film-forming method of the piezoelectric crystal film according to the first aspect, preferably, in the step of disposing the substrate and the disk in the film-forming space, the disk on which the substrate is placed is arranged in the film-forming space. An annular bearing seat, and the diameter of the outer peripheral portion of the bearing seat is larger than the diameter of the disc. According to the above configuration, since the outer circumference of the susceptor can be made larger than the outer circumference of the disk, the disk can be stably arranged on the susceptor. Also, since the portion of the susceptor exposed outside the radial direction of the disc can be placed close to the substrate, the material of the piezoelectric body adhering to the susceptor from the target can be evaporated and supplied to the substrate on the disc. Thereby, the piezoelectric crystal film can be more stably formed on the substrate.

In the film-forming method of the piezoelectric crystal film according to the first embodiment, preferably, in the step of heating the substrate, the substrate is heated to a temperature equal to or higher than the Curie point of the piezoelectric material, and further comprises: : After forming the piezoelectric crystal film on the substrate, further comprising a step of gradually cooling the substrate to a temperature below the Curie point of the piezoelectric material in the film formation space. According to the above configuration, since the orientation of the crystal can be reversed in a part of the piezoelectric crystal film, the piezoelectric constant d ₃₁ (the piezoelectric constant in the direction along the plane) of the piezoelectric can be increased.

In the film-forming method of the piezoelectric crystal film of the first aspect, preferably, the disk is formed of a base material containing silicon carbide, and the material of the piezoelectric body contains lead zirconate titanate. According to the above configuration, a high-quality piezoelectric crystal film containing lead zirconate titanate can be stably formed on the substrate by using the disk containing silicon carbide.

A disk system for forming a piezoelectric crystal film according to a second aspect of the present invention is disposed together with a substrate in a space for forming a piezoelectric film, and the disk system for forming a piezoelectric crystal film includes: a substrate mounting area for mounting a substrate and the disk body is made of ceramics, and the diameter of the outer edge of the exposed part of the base material on the side of the substrate carrying substrate is 1.05 to 1.15 times the diameter of the substrate carrying area.

In the disk for forming a piezoelectric crystal film according to the second aspect of the present invention, with the above configuration, since the substrate and the disk can be arranged in the film formation space, the disk can be selected according to the size of the substrate to crystallize the piezoelectric body. The film is formed on the substrate. That is, the substrate is disposed on a plate in which the diameter of the outer edge of the exposed portion of the base material on the side surface of the substrate carrying substrate is 1.05 to 1.15 times the diameter of the substrate carrying area, and the piezoelectric body is formed on the substrate. Crystalline film. Thereby, the substrate can be heated while the entire back surface of the substrate is in contact with the disk, and the temperature of the substrate can be stabilized. Also, by forming the diameter of the outer edge of the exposed portion of the substrate on the side surface of the substrate to be 1.15 times or less the diameter of the substrate mounting region, the exposed portion of the substrate of the disk can be prevented from becoming too large. Therefore, an increase in the amount of heat dissipation due to radiant heat from the exposed portion of the substrate of the disk can be suppressed. Thereby, the heat loss of the substrate through the disk can be suppressed, and the temperature unevenness of the substrate can be reduced, so as to reduce the unevenness of the film quality in the surface of the substrate. In addition, since the temperature can be easily controlled, it is possible to provide a disk for forming a piezoelectric crystal film capable of stably forming a piezoelectric crystal film with good film quality on a substrate. In addition, rapid cooling of the substrate after film formation can be suppressed by heat retention of the heat capacity of the disk, thereby suppressing deterioration of the film quality of the piezoelectric crystal film. Thereby, the temperature unevenness of the substrate can also be reduced, thereby reducing the unevenness of the film quality in the substrate surface. Also, by forming the diameter of the outer edge of the exposed portion of the substrate on the side surface of the substrate to be at least 1.05 times the diameter of the substrate mounting region, the exposed substrate of the disk can be easily formed in accordance with the diameter of the substrate. part.

1‧‧‧Piezoelectric crystal film film forming device

2, 2a‧‧‧Disk

3. 3a‧‧‧substrate

11‧‧‧Shell

12‧‧‧target

13‧‧‧bearing seat

14‧‧‧Heater

15‧‧‧Film-forming space

20‧‧‧Disk body

21, 21a‧‧‧recess

22, 22a‧‧‧positioning department

23. 23a‧‧‧Substrate carrying area

24‧‧‧Metallization layer

31, 31a‧‧‧body part

32‧‧‧Gap

32a‧‧‧Positioning plane

D1, D2‧‧‧diameter

D3‧‧‧inner diameter

D4‧‧‧outer diameter

D11, D12, D13‧‧‧diameter

T1, T2‧‧‧thickness

S1~S10‧‧‧Steps

Fig. 1 is a schematic diagram showing a piezoelectric crystal film forming apparatus for forming a piezoelectric crystal film according to an embodiment of the present invention.

Fig. 2 is a plan view showing a first example of a disk for forming a piezoelectric crystal film according to an embodiment of the present invention.

Fig. 3 is a sectional view along line III-III of Fig. 2 .

Fig. 4 is a plan view showing a second example of a disk for forming a piezoelectric crystal film according to an embodiment of the present invention.

Fig. 5 is a sequence diagram for explaining a method of forming a piezoelectric crystal film according to an embodiment of the present invention.

Fig. 6 is a table for explaining the film-forming states of Examples and Comparative Examples.

Hereinafter, embodiments of the present invention will be described based on the drawings.

(Structure of Piezoelectric Crystal Film Formation Device)

The structure of a piezoelectric crystal film forming apparatus for forming a piezoelectric crystal film according to an embodiment of the present invention will be described with reference to FIG. 1 .

A piezoelectric crystal film forming apparatus 1 for forming a piezoelectric crystal film according to an embodiment of the present invention includes a case 11, a target 12, a holder 13, a heater 14, and Film formation space 15 surrounded by casing 11 . In addition, the piezoelectric crystal film forming apparatus 1 is configured to form a piezoelectric crystal film on a substrate 3 arranged on a disk 2 . In addition, the disc 2 is an example of the "disk for forming a piezoelectric crystal film" described in the scope of the patent application.

The piezoelectric crystal film is configured to be deformed by applying a voltage. The piezoelectric crystal film system is formed of a ferroelectric material. For example, the piezoelectric crystal film is made of lead zirconate titanate (PZT(Pb(Zr,Ti)O ₃ )), bismuth titanate (BTO(Bi ₄ Ti ₃ O ₁₂ )), bismuth lanthanum titanate (BLT( (Bi,La) ₄ Ti ₃ O ₁₂ )), strontium bismuth tantalate (SBT(SrBi ₂ Ta ₂ O ₉ )), lead lanthanum zirconate titanate (PLZT((PbLa)(ZrTi)O ₃ )), in PZT Nb-doped PZNT and PZMT doped with Mn are formed.

The housing 11 is provided so as to surround the target 12, the mounting base 13, and the heater 14, and the film formation space 15 is configured to be sealable.

The target 12 is a material including a piezoelectric body. The material of the piezoelectric body includes, for example, at least one of PZT, BTO, BLT, SBT, and PLZT. In the film formation space 15, the target 12 is arrange|positioned so that it may oppose the mounting base 13. As shown in FIG. The target 12 is formed in a flat plate shape. The target 12 is connected to a power source for applying a voltage.

The carrier 13 is configured to support the disk 2 on which the substrate 3 is arranged. The bearing seat 13 is formed in an annular shape. Moreover, the bearing seat 13 is formed by ceramics. The bearing seat 13 is formed by, for example, silicon oxide (SiO ₂ ), silicon carbide (SiC) and the like. Also, the inner diameter D3 of the annular carrier 13 is formed to be smaller than the outer diameter of the disk 2 . Also, the annular carrier 13 has a diameter of the outer peripheral portion (outer diameter D4 ) larger than the diameter of the disk 2 . The material of the piezoelectric body is deposited on the part of the carrier seat 13 where the disk 2 is exposed. For example, when the piezoelectric material contains lead (Pb), the lead is evaporated from the piezoelectric material deposited on the susceptor 13 and supplied to the substrate 3 on the disk 2 . Thereby, the piezoelectric crystal film can be stably formed on the substrate 3 .

The heater 14 is configured to heat the substrate 3 . The heater 14 is configured to heat the substrate 3 by, for example, infrared rays. That is, the heater 14 is configured to heat the substrate 3 by radiant heat (radiation). The heater 14 is arranged on the side opposite to the target 12 with respect to the susceptor 13 . That is, the heater 14 is configured to be spaced apart from the disk 2 by a predetermined distance, and to heat the substrate 3 from the back surface (the surface opposite to the surface on which the piezoelectric crystal film is formed) of the substrate 3 .

In the present embodiment, the disk 2 is configured such that the substrate 3 is disposed on the upper surface thereof. That is, the substrate 3 is placed in a state of being in contact with the upper surface of the disk 2 . Disk 2 is formed by ceramics. The disk 2 is formed by, for example, a base material including silicon carbide (SiC). The disk 2 is configured to be inserted into and taken out from the piezoelectric crystal film forming apparatus 1 . That is, the disk 2 is configured to be placed in the piezoelectric crystal film forming apparatus 1 together with the substrate 3 and taken out from the piezoelectric crystal film forming apparatus 1 after film formation. In addition, the disc 2 has a thickness of about 2 mm to 5 mm when the diameter is about 210 mm to 230 mm, for example.

In addition, as shown in FIG. 2 , the disk 2 includes a disk body 20 , a concave portion 21 , a positioning portion 22 , and a substrate carrying area 23 . In the disk 2 (disk body 20 ), the diameter D2 of the exposed portion of the substrate 3 on the surface of the substrate 3 is 1.05 to 1.15 times the diameter D1 of the substrate 3 (substrate mounting region 23 ). Also, the disk 2 is in surface contact or line contact with the carrier 13 . That is, the disk 2 is in contact with the carrier 13 without play. This suppresses splashing of the material of the piezoelectric crystal film to the heater 14 side.

The concave portion 21 includes the substrate carrying area 23 to form the carrying substrate 3 . The concave portion 21 is formed in a circular shape. Also, the concave portion 21 is formed slightly larger than the diameter of the substrate 3 . Moreover, as shown in FIG. 3, the recessed part 21 has thickness T1. The thickness T1 of the concave portion 21 is, for example, about 2.5 mm.

As shown in FIG. 2 , the positioning unit 22 is configured to position the mounting position of the substrate 3 on the disk 2 . The positioning portion 22 is formed in a convex shape. In addition, the positioning portion 22 is formed on the surface of the disk 2 on the side of the carrier substrate 3 . Also, the positioning portion 22 is integrally provided on the disk 2 (disk body 20). The positioning portion 22 is formed along the outer periphery of the disc 2 . That is, the positioning portion 22 is provided on the periphery of the disk 2 . In addition, the positioning portion 22 has a thickness T2 as shown in FIG. 3 . The thickness T2 of the positioning portion 22 is, for example, about 5 mm.

The substrate carrier region 23 is formed as a carrier substrate 3 . The substrate mounting area 23 is formed in a flat shape.

As shown in FIG. 2 , the diameter of the disk 2 is larger than the inner diameter D3 of the bearing seat 13 . Moreover, the diameter of the disk 2 is smaller than the outer diameter D4 of the bearing base 13 .

The substrate 3 is formed of silicon, for example. Moreover, as shown in FIG. 2 , the substrate 3 has a main body portion 31 and a notch (notch) 32 . The substrate 3 has, for example, a diameter of 200 mm (a so-called 8-inch wafer). Also, the substrate 3 has a thickness of, for example, 725 μm. In addition, the diameter of the substrate 3 refers to the diameter of the circumferential portion excluding the notch 32 . In addition, as the substrate 3 , for example, a standard-standard wafer such as JEITA or ISO is used.

Here, referring to FIG. 4 , the disk 2 a and the substrate 3 a when the diameter of the substrate is less than 1/1.15 of the diameter of the disk will be described. In addition, the disc 2a is an example of the "disk for forming a piezoelectric crystal film" described in the claims.

The diameter D11 of the disk 2 a must be formed larger than the inner diameter D3 of the mounting seat 13 so that it can be mounted on the mounting seat 13 . For example, the diameter D11 of the disk 2 a is formed to be approximately equal to the diameter D2 of the disk 2 . The disc 2 a includes a recess 21 a, a positioning portion 22 a, a substrate carrying area 23 a, and a metallization layer 24 . In the disk 2a, the diameter D13 of the exposed portion of the substrate 3a on the surface of the substrate 3a is 1.05 to 1.15 times the diameter D12 of the substrate 3a (substrate mounting region 23a).

That is, the disc 2a is coated with a metallized layer 24 so that the diameter D13 of the exposed portion of the substrate on the surface of the disc 2a carrying the substrate 3a is 1.05 to 1.15 times the diameter D12 of the substrate 3a. The surface of the carrier substrate 3a of the disc 2a.

The metallization layer 24 is formed of, for example, platinum (Pt). Also, the metallization layer 24 is formed of, for example, zinc (Zr), titanium (Ti), iridium (Ir) or the like. Also, the metallization layer 24 is formed of, for example, tungsten (W), tantalum (Ta), molybdenum (Mo), niobium (Nb) or the like.

The metallization layer 24 is arranged on the side of the carrier substrate 3a of the disc 2a. That is, the metallization layer 24 is disposed on the opposite side of the heater 14 . Moreover, compared with the base material of the disc 2a, the metallization layer 24 is formed of a material that is not easy to radiate heat. Specifically, the metallization layer 24 is formed of a material with a lower emissivity than the substrate of the disk 2a. In addition, the metallization layer 24 is formed of a material that can withstand high temperature during film formation (does not dissolve). The metallization layer 24 is disposed on the surface of the positioning portion 22a.

In addition, the recessed portion 21a, the positioning portion 22a, and the substrate carrying area 23a have the same structures as the recessed portion 21, the positioning portion 22, and the substrate carrying area 23, respectively.

The base plate 3a has a main body portion 31a and a positioning plane 32a. The substrate 3 a has, for example, a diameter of 150 mm (a so-called 6-inch wafer). In addition, the substrate 3 a has a thickness of, for example, 625 μm. In addition, the diameter of the board|substrate 3a means the diameter of the circumferential part except the positioning plane 32a. In addition, as the substrate 3a, for example, a standard-standard wafer such as JEITA or ISO is used.

(Film formation method of piezoelectric crystal film)

Next, a method for forming a piezoelectric crystal film will be described.

The film-forming method of the piezoelectric crystal film includes: a step of arranging the substrate 3 on the disk 2; a step of arranging the substrate 3 and the disk 2 in the film-forming space 15; a step of heating the substrate 3 from the side of the disk 2; A step of supplying argon gas (inert gas) into the film formation space 15 ; a step of applying a voltage to the target 12 ; and a step of forming a piezoelectric crystal film on the substrate 3 .

Specifically, as shown in FIG. 5 , in step S1 , the substrate 3 is placed on the disk 2 . More specifically, the substrate 3 is placed on the disk 2 made of ceramics and the diameter of the exposed portion of the substrate on the surface carrying the substrate 3 is 1.05 times to 1.15 times the diameter of the substrate 3 . More preferably, the disc 2 in which the substrate 3 is placed on the surface of the carrier substrate 3 and the diameter of the exposed portion of the substrate is 1.05 to 1.125 times the diameter of the substrate 3 is preferred. At this time, the substrate 3 is positioned on the disk 2 by the convex positioning portion 22 formed on the surface of the disk 2 carrying the substrate 3 . In addition, a lower electrode is formed on the substrate 3 in advance. Furthermore, a piezoelectric crystal film is formed on the lower electrode of the substrate 3 .

In step S2 , the substrate 3 and the disk 2 are arranged in the film forming space 15 . Specifically, the substrate 3 is arranged together with the disk 2 so as to face the target 12 of a material including a piezoelectric body arranged in the film formation space 15 . At this time, the disc 2 on which the substrate 3 is placed is arranged in the film-forming space 15 on the annular carrier 13 , and the outer peripheral portion of the carrier 13 has a diameter larger than that of the disc 2 . In addition, since the inside of the film-forming space 15 is depressurized (approximately vacuum pressure), the substrate 3 and the disk 2 are arranged in the film-forming space 15 by a robot arm (not shown).

In step S3 , the substrate 3 is heated by the heater 14 . The substrate 3 is heated to a temperature equal to or higher than the Curie point of the piezoelectric material. For example, the substrate 3 is heated to 500-700°C. In step S4 , argon gas is supplied into the film formation space 15 . In step S5 , a voltage is applied to the target 12 . Thereby, the argon gas in the film formation space 15 is ionized to generate plasma. In addition, the ions in the film formation space 15 collide with the target 12, and the particles of the piezoelectric material (for example, PZT) are ejected. The particles of the ejected piezoelectric material reach the opposite substrate 3 to form a piezoelectric crystal film.

After a predetermined time elapses and the piezoelectric crystal film is formed on the substrate 3 , in step S6 , the voltage application to the target 12 is stopped. In step S7, the supply of argon gas into the film formation space 15 is stopped. In step S8, the heater 14 is turned off, and the heating of the substrate 3 is stopped.

In step S9, the substrate 3 is gradually cooled in the film formation space 15 (in the atmosphere of the piezoelectric material (for example, PZT)). At this time, the substrate 3 is gradually cooled from a temperature above the Curie point of the piezoelectric material to a temperature below the Curie point. For example, the substrate 3 is slowly cooled from about 550° C. to about 350° C. in about 1 minute to 30 minutes. Ideally, the substrate 3 is slowly cooled in such a manner that the substrate 3 is only lowered by about 200° C. in about 20 minutes. Thereby, for example, in the formed PZT film, part of the crystal orientation is reversed from the c-domain to the a-domain. Thereby, the piezoelectric constant d ₃₁ (the piezoelectric constant along the plane direction) can be increased. In addition, in the case of a piezoelectric crystal film of PZT, it is desirable that the orientation of the crystals is about 30% to 40% in the a domain. In addition, when gradually cooling in step S9, it is preferable to gradually cool after raising the temperature before cooling (in-situ annealing). When rapid cooling is performed without slow cooling, the amount of inversion from the c domain to the a domain is suppressed, and more than 80% of the crystal orientation is oriented to the c domain.

In step S10 , the substrate 3 and the disk 2 are taken out from the film formation space 15 . In addition, since the inside of the film-forming space 15 is decompressed (approximately vacuum pressure), the substrate 3 and the disk 2 are taken out from the film-forming space 15 by a robot arm (not shown). Through the above steps, the piezoelectric crystal film is formed on the substrate 3 .

(Effect of Embodiment)

In this embodiment, the following effects can be obtained.

In this embodiment, as described above, since the substrate 3 can be arranged in the film forming space 15 together with the disk 2 , the disk 2 can be selected according to the size of the substrate 3 to form a piezoelectric crystal film on the substrate 3 . That is, the substrate 3 is placed on the disk 2 in which the exposed portion of the substrate on the surface of the carrier substrate 3 has a diameter of 1.05 times to 1.15 times the diameter of the substrate, and a piezoelectric crystal film is formed on the substrate 3 . Thereby, the substrate 3 can be heated in a state where the entire back surface of the substrate 3 is in contact with the disk 2, and the temperature of the substrate 3 can be stabilized. On the other hand, when heating is performed without using the disk 2, the Pb content of the piezoelectric body is uneven due to temperature unevenness in the surface of the substrate 3 during temperature rise, so that the performance in the surface of the substrate 3 is unstable. Also, by forming the diameter of the exposed portion of the base material on the surface of the carrying substrate to be 1.15 times or less the diameter of the substrate 3, since the exposed portion of the base material of the disk 2 can be suppressed from becoming too large, it is possible to suppress the 2. The amount of heat dissipation due to the radiant heat of the exposed portion of the base material increases. Thereby, the heat loss of the substrate 3 can be suppressed through the disk 2, and the temperature unevenness of the substrate 3 can be reduced, so as to reduce the unevenness of the film quality in the substrate surface. In addition, since the temperature can be easily controlled, a piezoelectric crystal film with good film quality can be stably formed on the substrate 3 . In addition, the rapid cooling of the substrate 3 after film formation can be suppressed due to the heat retention of the heat capacity of the disk 2, thereby suppressing the deterioration of the film quality of the piezoelectric crystal film. Thereby, the temperature unevenness of the substrate 3 can also be reduced, thereby reducing the unevenness of the film quality in the substrate surface. On the other hand, when cooling is performed without using the disk 2, since the wafer (substrate 3) is thin, the in-plane temperature drops unevenly, resulting in uneven area ratio (orientation). Ideally, by disposing the substrate 3 on the disk 2 with a diameter of 1.05 to 1.15 times the diameter of the substrate 3, when the temperature of the substrate 3 rises and falls, the temperature control becomes easier and the film quality is improved, and since the substrate 3 is lowered, The uneven temperature further reduces the unevenness of the film quality in the substrate 3 surface. In addition, by making the diameter of the exposed portion of the substrate on the surface carrying the substrate 1.05 times or more the diameter of the substrate 3, the exposed portion of the substrate of the disc 2 can be easily formed in accordance with the diameter of the substrate 3.

In addition, in the present embodiment, in the step of placing the substrate 3 on the tray 2 , the substrate 3 is positioned on the tray 2 by the convex positioning portion 22 formed on the surface of the tray 2 carrying the substrate 3 . Thereby, since the entire back surface of the substrate 3 can be easily disposed on the exposed portion of the base material of the disc 2 , heat can be evenly transferred to the base plate 3 through the base material of the disc 2 . In addition, when the disk 2 on which the substrate 3 is arranged is moved, the positioning portion 22 can suppress deviation of the substrate 3 from the disk 2 .

Also, in the present embodiment, the positioning portion 22 of the disk 2 is formed along the outer periphery of the disk 2 . Thereby, since the convex positioning part 22 can be arrange|positioned on the outer periphery of the disk 2, the heat capacity of the outer periphery of the disk 2 can be increased. As a result, the temperature on the outer peripheral side of the substrate 3 can be suppressed from being lower than that on the central side, and the piezoelectric crystal film can be stably formed.

In addition, in this embodiment, the diameter of the exposed portion of the base material on the surface of the carrier substrate 3a of the disc 2a is 1.05 times to 1.15 times the diameter of the substrate 3a, and the carrier substrate of the disc 2a is covered with a metal. 3a face. Thereby, since heat radiation from the disk 2a can be suppressed by the coating of the metal, the piezoelectric crystal film can be formed stably even on the substrate 3a having a diameter less than 1/1.15 times the diameter of the disk 2a. membrane.

Also, in the present embodiment, in the step of arranging the substrate 3 together with the disk 2 in the film-forming space 15, the disk 2 on which the substrate 3 is placed is arranged on the annular carrier 13 in the film-forming space 15, The bearing seat 13 has a peripheral portion whose diameter is larger than that of the disk 2 . Thereby, since the outer circumference of the susceptor 13 can be made larger than the outer circumference of the disc 2, the disc 2 can be stably arranged on the susceptor 13. In addition, since the portion of the mounting base 13 exposed outside the diameter direction of the disk 2 can be placed close to the substrate 3, the material of the piezoelectric body attached to the mounting base 13 from the target 12 can be evaporated and supplied to the surface of the disk 2. substrate3. Thereby, the piezoelectric crystal film can be more stably formed on the substrate 3 .

In addition, in the present embodiment, in the step of heating the substrate 3, the substrate 3 is heated to a temperature equal to or higher than the Curie point of the piezoelectric material, and after the piezoelectric crystal film is formed on the substrate 3, the forming device is provided. A step of gradually cooling the substrate 3 in the membrane space 15 to a temperature equal to or lower than the Curie point of the piezoelectric material. Thereby, since the orientation of the crystal can be reversed in a part of the piezoelectric crystal film, the piezoelectric constant d ₃₁ (the piezoelectric constant in the direction along the plane) of the piezoelectric can be increased.

Also, in the present embodiment, the disk 2 is formed from a base material including silicon carbide (SiC), and the material of the piezoelectric body includes lead zirconate titanate (PZT). Thereby, using the disk 2 made of silicon carbide (SiC), a piezoelectric crystal film made of lead zirconate titanate (PZT) with good film quality can be stably formed on the substrate 3 .

(Description of Example)

Next, with reference to FIG. 6, the experimental results (example) for evaluating the film-forming state of the piezoelectric crystal film according to the present embodiment will be described.

As shown in FIG. 6, in Example 1, Example 2, Example 3 and Comparative Example, the diameter D1 of the substrate is 200 mm (so-called 8-inch wafer). In Example 1, the diameter D2 of the exposed portion of the base material on the surface of the disc carrying the substrate was 210 mm. That is, in Example 1, D2 was 1.05 times D1. In Example 2, the diameter D2 of the exposed portion of the base material on the surface of the disc carrying the substrate was 225 mm. That is, in Example 2, D2 was 1.125 times D1. In Example 3, the diameter D2 of the exposed portion of the base material on the surface of the disc carrying the substrate was 230 mm. That is, in Example 3, D2 was 1.15 times D1. In the comparative example, the diameter D2 of the portion where the base material was exposed on the surface of the disc carrying the substrate was 250 mm. That is, in the comparative example, D2 is 1.25 times of D1.

As described above, in Example 1, Example 2, Example 3, and Comparative Example, although the diameter D2 of the disk on which the substrate is placed is different, the piezoelectric crystal film is formed under the same conditions in other parts.

As shown in FIG. 3 , in Example 1, a piezoelectric crystal film with good film quality was stably formed. The piezoelectric crystal film is formed substantially uniformly (flatly) over the entire substrate.

In Example 2, a piezoelectric crystal film with good film quality was stably formed. In Example 2, the piezoelectric crystal film was formed substantially uniformly (flatly) over the entire substrate.

In Example 3, a piezoelectric crystal film with good film quality was formed. However, there are cases where a piezoelectric crystal film with unstable film quality is formed, but generally a piezoelectric crystal film with good film quality is formed.

In the comparative example, irregularities were formed on the surface of the piezoelectric crystal film to form a cloudy film. In the comparative example, the piezoelectric crystal film was formed unevenly on the center side and the outer peripheral side of the substrate.

As can be seen from the above, in Examples 1 to 3, the piezoelectric crystal film is formed on the substrate by using a disk having a diameter of 1.05 times to 1.15 times the diameter of the substrate at which the substrate is exposed on the surface of the substrate. For film formation, a piezoelectric crystal film with good film quality can be stably formed on the substrate.

(Modification)

In addition, the embodiment and the Example of this indication are an illustration in every respect, and are not restrictive. The scope of the present invention is based on what is shown in the claims rather than the description of the above-mentioned embodiments and examples, and also includes the meanings equivalent to the claims and various changes (modifications) within the scope.

For example, in the above-mentioned embodiments, an example in which the positioning portion of the disk is formed along the outer periphery of the disk was shown, but the present invention is not limited thereto. In the present invention, the positioning portion of the disk may be divided into a plurality of dots or lines and provided.

Also, in the above-mentioned embodiment, an example of the structure in which the disk positioning portion is provided on the periphery of the disk was shown, but the present invention is not limited thereto. In the present invention, the positioning portion of the disk may be provided at a center side portion separated from the periphery of the disk.

In addition, in the above-mentioned embodiment, an example of the structure in which the substrate is heated by heat radiation (radiant heat) of the heater was shown, but the present invention is not limited thereto. In the present invention, the heater can also be arranged in contact with the disk or the carrier to heat the substrate by heat conduction.

In addition, in the above embodiment, an example of the structure in which a metallization layer is provided on the surface of the positioning portion is shown, but the present invention is not limited thereto. In the present invention, the coated metal may also be provided in the concave portion or the like.

Also, in the above embodiments, an example in which the piezoelectric crystal film includes a ferroelectric film was shown, but the present invention is not limited thereto. In the present invention, the piezoelectric crystal film may be a piezoelectric crystal film other than the ferroelectric film.

2‧‧‧disk

3‧‧‧substrate

13‧‧‧bearing seat

20‧‧‧Disk body

21‧‧‧Concave

22‧‧‧Positioning Department

23‧‧‧Substrate carrying area

31‧‧‧Body Department

32‧‧‧Gap

D1‧‧‧diameter

D2‧‧‧diameter

D3‧‧‧inner diameter

D4‧‧‧outer diameter

Claims (12)

A method for forming a piezoelectric crystal film, comprising: a step of disposing a substrate on a disk, the disk being made of ceramics and the outer edge of the exposed part of the base material belonging to the ceramics on the surface of the side carrying the substrate The diameter of the portion is not less than 1.05 times and not more than 1.15 times the diameter of the aforementioned substrate; a step of arranging the aforementioned substrate and the aforementioned disk so as to face a target of a material including a piezoelectric body arranged in the film formation space; from the side of the aforementioned disk a step of heating the substrate; a step of applying a voltage to the target; and a step of forming a piezoelectric crystal film on the substrate. The method for forming a piezoelectric crystal film according to claim 1, wherein, in the step of arranging the substrate on the disk, the protrusions formed on the surface of the disk on which the substrate is placed The shape positioning part positions the substrate and arranges the substrate on the disk. The method for forming a piezoelectric crystal film according to claim 2, wherein the positioning portion of the disk is formed along the outer periphery of the disk. The method of forming a piezoelectric crystal film according to any one of claims 1 to 3 of the patent claims, wherein, in the tray, the exposed part of the base material on the side surface of the substrate is used The portion of the surface on the side on which the substrate is placed, other than the substrate mounting region on which the substrate is mounted, is covered with a metal so that the diameter is 1.05 times to 1.15 times the diameter of the substrate. Piezoelectric junction as described in any one of items 1 to 3 of the scope of application A method for forming a crystal film, wherein, in the step of arranging the substrate and the tray in the film-forming space, the tray on which the substrate is placed is placed on an annular carrier in the film-forming space. Seat, and the diameter of the peripheral part that this bearing seat has is larger than the diameter of aforementioned disk. The method for forming a piezoelectric crystal film according to any one of claims 1 to 3, wherein, in the step of heating the substrate, the substrate is heated to the Curie point of the piezoelectric material The above temperature further includes the step of gradually cooling the substrate to a temperature below the Curie point of the piezoelectric material in the film formation space after forming the piezoelectric crystal film on the substrate. The method for forming a piezoelectric crystal film according to any one of claims 1 to 3 of the patent claims, wherein, in the tray, the exposed portion of the base material on the side surface on which the substrate is placed is In such a manner that the diameter is not less than 1.05 times and not more than 1.15 times the diameter of the substrate, the portion of the surface on which the substrate is placed, other than the substrate-carrying area where the substrate is placed, is covered with a metal; in the step of heating the substrate, the substrate is heated to a temperature above the Curie point of the piezoelectric material; further comprising: after forming the piezoelectric crystal film on the substrate, slowly cooling the substrate to the Curie point of the piezoelectric material in the film-forming space. Point the steps below for the temperature. The method for forming a piezoelectric crystal film according to any one of claims 1 to 3 of the patent claims, wherein in the step of arranging the substrate and the disk in the film-forming space, the placed The aforementioned tray with the aforementioned substrate is disposed on a ring-shaped bearing seat in the aforementioned film forming space, and The diameter of the outer peripheral portion of the carrying seat is larger than the diameter of the aforementioned disk; in the step of heating the aforementioned substrate, the aforementioned substrate is heated to a temperature above the Curie point of the piezoelectric body material; After the piezoelectric crystal film is formed, the substrate is gradually cooled to a temperature below the Curie point of the piezoelectric material in the film formation space. The method for forming a piezoelectric crystal film according to any one of claims 1 to 3 of the patent application, wherein the disk is formed of a base material containing silicon carbide, and the material of the piezoelectric body contains zirconium titanic acid lead. The method for forming a piezoelectric crystal film according to claim 4, wherein the portion outside the exposed portion of the base material on the surface carrying the base plate in the tray is formed with the base material Covered by different materials. The method for forming a piezoelectric crystal film according to any one of claims 1 to 3, wherein the diameter of the disk is equal to the outer edge of the exposed portion of the substrate on the surface on which the substrate is placed. the diameter of the section. A disk for forming a piezoelectric crystal film is arranged together with a substrate in a space for forming a piezoelectric film. The disk system for forming a piezoelectric crystal film includes: a substrate carrying area for carrying the substrate; and a disk body. , is made of ceramics, and the diameter of the outer edge portion of the exposed part of the base material belonging to the ceramics on the surface of the side carrying the substrate is 1.05 to 1.15 times the diameter of the substrate carrying area.

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