JP5196106B2 - Method for manufacturing piezoelectric element - Google Patents

Description

  The present invention relates to a piezoelectric element manufacturing method, an ink jet recording head, and an ink jet printer.

Inkjet printers are known as printers that enable high image quality and high-speed printing. The ink jet printer includes an ink jet recording head having a cavity whose internal volume changes, and performs printing by ejecting ink droplets from the nozzle while scanning the head. As a head actuator in an ink jet recording head for such an ink jet printer, a piezoelectric element using a piezoelectric layer represented by PZT (Pb (Zr, Ti) O ₃ ) has been conventionally used (for example, (See Patent Document 1). In addition to inkjet printers, piezoelectric elements are also used in devices such as piezoelectric pumps, surface acoustic wave elements, thin film piezoelectric resonators, frequency filters, oscillators, electronic circuits, and electronic equipment. Since such a piezoelectric element has a crystal structure, there is a problem in that the uniformity and reliability of the displacement amount are lost due to various damages in the manufacturing process.
JP 2001-223404 A

  An object of the present invention is to provide a piezoelectric element that recovers damage received in the manufacturing process and has excellent uniformity of displacement and reliability, an ink jet recording head including the piezoelectric element, and an ink jet printer. .

The method for manufacturing a piezoelectric element according to the present invention includes:
(A) forming a first electrode above the substrate side;
(B) forming a piezoelectric layer above the first electrode;
(C) forming a second electrode above the piezoelectric layer;
(D) patterning at least a part of the second electrode and the piezoelectric layer to form a capacitor structure having the first electrode, the piezoelectric layer, and the second electrode;
(E) forming a protective film covering at least a part of the capacitor structure;
(F) performing a first annealing;
(G) forming a wiring film electrically connected to the upper electrode;
including.

  In the present invention, when a specific B member (hereinafter referred to as “B member”) provided above a specific A member (hereinafter referred to as “A member”), the B member directly on the A member. The meaning includes the case where it is provided and the case where the B member is provided on the A member via another member.

In the method for manufacturing a piezoelectric element according to the present invention,
The step (e)
(E1) forming a protective film;
(E2) patterning the protective film;
Can have.

In the method for manufacturing a piezoelectric element according to the present invention,
The step (b)
Applying a precursor solution of the piezoelectric layer above the first electrode;
Performing crystallization annealing of the precursor solution;
Have
The temperature of the first annealing in the step (f) can be lower than the temperature of the crystallization annealing.

In the method for manufacturing a piezoelectric element according to the present invention,
Between the steps (e1) and (e2),
The method may further include performing a second annealing.

In the method for manufacturing a piezoelectric element according to the present invention,
The step (b)
Applying a precursor solution of the piezoelectric layer above the first electrode;
Performing crystallization annealing of the precursor solution;
Have
The temperature of the second annealing may be lower than the temperature of the crystallization annealing.

In the method for manufacturing a piezoelectric element according to the present invention,
Between the steps (c) and (d),
The method may further include performing a third annealing.

In the method for manufacturing a piezoelectric element according to the present invention,
The step (b)
Applying a precursor solution of the piezoelectric layer above the first electrode;
Performing crystallization annealing of the precursor solution;
Have
The temperature of the third annealing may be lower than the temperature of the crystallization annealing.

In the method for manufacturing a piezoelectric element according to the present invention,
The step (b)
Applying a precursor solution of the piezoelectric layer above the first electrode;
Performing crystallization annealing of the precursor solution;
Have
Between the steps (b) and (c),
The method may further include performing a fourth annealing.

In the method for manufacturing a piezoelectric element according to the present invention,
The step (b)
Applying a precursor solution of the piezoelectric layer above the first electrode;
Performing crystallization annealing of the precursor solution;
Have
The temperature of the fourth annealing may be lower than the temperature of the crystallization annealing.

In the method for manufacturing a piezoelectric element according to the present invention,
The first annealing may be performed in an oxygen atmosphere.

  An ink jet recording head according to the present invention includes a piezoelectric element manufactured by the manufacturing method described above.

  An ink jet printer according to the present invention includes the ink jet recording head described above.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

1. Method for Manufacturing Piezoelectric Element A method for manufacturing the piezoelectric element 100 according to the present embodiment will be described. The piezoelectric element 100 according to the present embodiment is applied to an ink jet recording head 1000. FIG. 1 is a flowchart showing a method for manufacturing the piezoelectric element 100. 2 to 14 are cross-sectional views schematically showing a method for manufacturing the piezoelectric element 100 and the ink jet recording head 1000 according to the embodiment of the present invention. The illustrated structure is drawn around a portion that is deformed by a piezoelectric operation, which is a main part of the ink jet recording head 1000, that is, the piezoelectric element 100 (see FIGS. 13 and 14). Here, for convenience of explanation, a simple example is shown, and the structure of the present embodiment is not limited to the structure shown here.

  (1) First, as shown in FIG. 2, a substrate 10 as a part of a base is prepared (step S100). The substrate 10 has, for example, a silicon layer 12 and an oxide layer 14. The oxide layer 14 may be silicon oxide provided by oxidizing the upper portion of the silicon layer 12, or silicon oxide or other oxidation newly provided on the upper surface of the silicon layer 12 by a known method. It may be a thing. The oxide layer 14 can be provided by thermal oxidation treatment or the like. Alternatively, when the oxide layer 14 is separately provided on the upper portion of the substrate 10, a known method such as vapor deposition or sputtering can be used.

  (2) Next, as shown in FIG. 3, the elastic body layer 20 is formed on the substrate 10 (step S100). The elastic layer 20 can be formed by a known method such as a sputtering method, vacuum deposition, or a chemical vapor deposition method (CVD method). As a material of the elastic layer 20, for example, zirconium oxide, silicon nitride, silicon oxide, or aluminum oxide is suitable. When the oxide layer 14 is provided on the upper surface of the substrate 10, the material of the elastic body layer 20 may be the same as or different from the material of the oxide layer 14. For example, the elastic body layer 20 can be formed to a thickness of, for example, 500 nm by sputtering using a material of zirconium oxide.

(3) Next, as shown in FIG. 4, the lower electrode layer 30 (first electrode) is formed on the elastic body layer 20 (step S102). The lower electrode layer 30 can be formed by a known method such as sputtering, vacuum deposition, or CVD. As the material of the lower electrode layer 30, various metals such as nickel, iridium, and platinum, conductive oxides thereof (for example, iridium oxide), composite oxides such as SrRuO ₃ and LaNiO ₃ , and the like can be used. Further, the lower electrode layer 30 may be a single layer of the exemplified materials or a structure in which a plurality of materials are stacked. For example, the lower electrode layer 30 is made of platinum and can be formed to a thickness of, for example, 100 nm by sputtering.

  (4) Next, as shown in FIG. 5, the piezoelectric layer 40 is formed on the lower electrode layer 30 (step S104). The piezoelectric layer 40 is formed using a liquid phase method such as a sol-gel method or a metal organic thermal coating decomposition method (MOD method) or a CVD method. The material of the piezoelectric layer 40 can be an oxide containing lead, zirconium, and titanium as constituent elements. That is, lead zirconate titanate (hereinafter referred to as PZT) is suitable as a material for the piezoelectric layer 40 because of its good piezoelectric performance. For example, when using the sol-gel method, a solution in which an organometallic compound containing Pb, Zr, and Ti is dissolved in a solvent is applied on the lower electrode layer 30, and then a drying step and a degreasing step, Then, the piezoelectric layer 40 can be formed through the crystallization annealing process. A drying process can be performed at about 100 to 200 degreeC, for example. A degreasing process can be performed at about 300 to 400 degreeC, for example. Crystallization annealing can be performed at about 600 ° C. to 800 ° C., for example. By repeating the above series of steps, the piezoelectric layer 40 having a desired film thickness can be obtained. The film thickness of the piezoelectric layer 40 can be, for example, 50 nm to 1500 nm.

(5) Next, as shown in FIG. 6, the upper electrode layer 50 (second electrode) is formed on the piezoelectric layer 40 (step S106). The upper electrode layer 50 can be formed by a known method such as sputtering, vacuum deposition, or CVD. As the material of the upper electrode layer 50, various metals such as nickel, iridium and platinum, conductive oxides thereof (for example, iridium oxide, etc.), composite oxides such as SrRuO ₃ and LaNiO ₃ , and the like can be used. Further, the upper electrode layer 50 may be a single layer of the exemplified materials or a structure in which a plurality of materials are stacked. For example, the upper electrode layer 50 is made of platinum and can be formed to a thickness of, for example, 100 nm by sputtering. In this way, the capacitor structure 60 including the lower electrode layer 30, the piezoelectric layer 40, and the upper electrode layer 50 can be formed.

  (6) Next, as shown in FIG. 7, by patterning the ferroelectric layer 40 and the upper electrode layer 50, the ferroelectric layer 42, the upper electrode layer 52, and the lower electrode layer 30 having predetermined shapes are formed. The capacitor structure part 62 including it is formed (step S108). The patterning can be performed by a known photolithography technique and dry etching or ion milling.

  (7) Next, as shown in FIG. 8, a protective film 70 is formed on the upper surface and side surfaces of the capacitor structure 62 (step S110). As a method for forming the protective film 70, a known sputtering method, CVD method, or the like can be used. As a material of the protective film 70, for example, aluminum oxide or silicon oxide can be used.

  (8) Next, as shown in FIG. 9, the protective film 70 is patterned (step S112). The patterning is performed to expose the upper surface of the upper electrode layer 52, for example. By patterning the protective film 70, the wiring film 80 formed above the protective film 70 and the upper electrode layer 52 can be electrically connected. The patterning can be performed by a known photolithography technique and dry etching or ion milling.

  (9) Next, annealing (first annealing) is performed (step S114). Annealing can be performed using, for example, a diffusion furnace or an RTA apparatus. By using the diffusion furnace, the surface of the substrate 10 can be heated uniformly. The annealing temperature can be 450 ° C. to 600 ° C., for example, and is preferably lower than the crystallization annealing temperature when forming the piezoelectric layer 40 described above. Further, annealing is performed in an oxygen atmosphere. By heating in an oxygen atmosphere, oxygen vacancies in the piezoelectric layer 42 are compensated, and the crystallinity can be recovered satisfactorily. Also, the annealing may be performed in an inert gas atmosphere such as a nitrogen atmosphere. Annealing is performed, for example, for about 30 to 60 minutes when a diffusion furnace is used.

  (10) Next, as shown in FIG. 10, a wiring film 80 is formed (step S116). The formation of the wiring film 80 can be performed by a known method such as sputtering, vacuum deposition, or CVD. As the material of the wiring film 80, various metals such as nickel, chromium, gold, or a compound thereof can be used. Further, the wiring film 80 may be a single layer of the exemplified materials or a structure in which a plurality of materials are stacked. For example, the wiring film 80 can be made of nickel chrome and gold laminated thereon.

  (11) Next, as shown in FIG. 11, the wiring film 80 is patterned (step S <b> 116) to form the wiring film 82. The patterning can be performed by a known photolithography technique and dry etching or ion milling. By patterning the wiring film 80, the plurality of capacitor structure portions 62 can be disconnected from each other, and different operations can be performed for each capacitor structure portion 62.

  (12) Next, as shown in FIG. 12, the sealing plate 90 is fixed above the base 10 (step S118). The sealing plate 90 can seal the capacitor structure 62 and can support the substrate 10, the elastic body layer 20, and the capacitor structure 62. The sealing plate 90 can be made of a material such as silicon. The sealing plate 90 may be fixed so as to be in contact with the capacitor structure portion 62 or may be fixed so as not to be in contact.

  (13) Next, as shown in FIG. 13, the pressure generating chamber 16 is formed in the substrate 10 (step S120). The pressure generating chamber 16 is obtained by forming a concave hole from the lower surface of the substrate 10 using a known anisotropic etching technique.

  Thereafter, as shown in FIG. 14, the nozzle plate 18 is bonded under the substrate 10. As the nozzle plate 18, a stainless plate having an opening can be used. The pressure generation chamber 16 is formed below the substrate 10 corresponding to the capacitor structure 62. The pressure generating chamber 16 is filled with liquid when the ink jet recording head 1000 is driven. The liquid filled in the pressure generating chamber 16 is pressurized by the operation of the piezoelectric element 100. The pressure generating chamber 16 has a function of discharging the liquid through the opening of the nozzle plate 18 by the pressure.

  Through the above steps, the ink jet recording head 1000 having the piezoelectric element 100 can be manufactured. According to the method of manufacturing the ink jet recording head 1000 according to the present embodiment, annealing is performed after the formation of the protective film 72 (step S114). Therefore, when the upper electrode layer 50 and the piezoelectric layer 40 are etched, The damage received by the capacitor structure 62 during the formation and etching of the protective film 70 can be recovered. Furthermore, in this embodiment, since annealing is performed after the protective film 70 is patterned, heat is easily transferred to the capacitor structure 62 inside the protective film 72, and damage can be efficiently recovered.

2. Modified Example Next, a method for manufacturing an ink jet recording head according to a modified example will be described.

2.1. First Modification FIG. 15 is a flowchart showing a manufacturing process of an ink jet recording head according to a first modification. The manufacturing method of the ink jet recording head according to the first modification is different from the manufacturing method of the ink jet recording head described above in that it further includes a step of annealing before patterning of the protective film 70. The specific manufacturing process is as follows.

  First, the above-described 1. Steps (1) to (7) are performed (steps S200 to S210). Next, annealing (second annealing) is performed (step S211). Annealing can be performed using, for example, a diffusion furnace or an RTA apparatus. Annealing is performed, for example, for about 30 to 60 minutes when a diffusion furnace is used. By using the diffusion furnace, the surface of the substrate 10 can be heated uniformly. The annealing temperature can be 450 ° C. to 600 ° C., for example, and is preferably lower than the crystallization annealing temperature when forming the piezoelectric layer 40 described above. Further, annealing is performed in an oxygen atmosphere. By heating in an oxygen atmosphere, oxygen vacancies in the piezoelectric layer 42 are compensated, and the crystallinity can be recovered satisfactorily. Also, the annealing may be performed in an inert gas atmosphere such as a nitrogen atmosphere.

  Next, the above-described 1. By performing the steps (8) to (13) (steps S212 to S220), an ink jet recording head can be manufactured.

  By performing the annealing in step S211, damage received by the capacitor structure 62 when the upper electrode layer 50 and the piezoelectric layer 40 are etched and when the protective film 70 is formed can be recovered.

2.2. Second Modification FIG. 16 is a flowchart showing a manufacturing process of an ink jet recording head according to a second modification. The method for manufacturing the ink jet recording head according to the second modification example is further described above in that it further includes a step of annealing before patterning the protective film 70 and a step of performing annealing after the upper electrode layer 50 is formed. This is different from the manufacturing method of the ink jet recording head. The specific manufacturing process is as follows.

  First, the above-described 1. Steps (1) to (5) are performed (steps S300 to S306).

  Next, annealing (third annealing) is performed (step S307). Annealing can be performed using, for example, a diffusion furnace or an RTA apparatus. Annealing is performed, for example, for about 60 to 180 minutes when a diffusion furnace is used. By using the diffusion furnace, the surface of the substrate 10 can be heated uniformly. The annealing temperature can be, for example, 300 ° C. to 800 ° C., and is preferably lower than the crystallization annealing temperature when forming the piezoelectric layer 40 described above. By performing annealing at such a temperature, the crystallinity of the piezoelectric layer 40 can be more reliably recovered to a good state. Further, the annealing may be performed in an oxygen atmosphere or in an inert gas atmosphere such as a nitrogen atmosphere.

  Next, the above-described 1. Steps (6) and (7) are performed (steps S308 to S310). Next, annealing (second annealing) is performed (step S311). Annealing can be performed using, for example, a diffusion furnace or an RTA apparatus. Annealing is performed, for example, for about 30 to 60 minutes when a diffusion furnace is used. By using the diffusion furnace, the surface of the substrate 10 can be heated uniformly. The annealing temperature can be 450 ° C. to 600 ° C., for example, and is preferably lower than the crystallization annealing temperature when forming the piezoelectric layer 40 described above. Further, annealing is performed in an oxygen atmosphere. By heating in an oxygen atmosphere, oxygen vacancies in the piezoelectric layer 42 are compensated, and the crystallinity can be recovered to a good state. Also, the annealing may be performed in an inert gas atmosphere such as a nitrogen atmosphere.

  Next, the above-described 1. By performing the steps (8) to (13) (steps S312 to S320), an ink jet recording head can be manufactured.

  By performing the annealing in step S311, damage received by the capacitor structure 62 when the upper electrode layer 50 and the piezoelectric layer 40 are etched and when the protective film 70 is formed can be recovered. Moreover, the oxygen deficiency of the piezoelectric layer 40 can be compensated by performing the annealing in step S307.

2.3. Third Modification FIG. 17 is a flowchart showing a manufacturing process of an ink jet recording head according to a third modification. The manufacturing method of the ink jet recording head according to the third modification includes a step of annealing before patterning of the protective film 70, a step of annealing after film formation of the upper electrode layer 50, and a film formation of the piezoelectric layer 40. It differs from the above-described method for manufacturing an ink jet recording head in that it further includes a step of performing annealing later. The specific manufacturing process is as follows.

  First, the above-described 1. Steps (1) to (4) are performed (steps S400 to S404).

  Next, annealing (fourth annealing) is performed (step S405). Annealing can be performed using, for example, a diffusion furnace or an RTA apparatus. Annealing is performed, for example, for about 60 to 180 minutes when a diffusion furnace is used. By using the diffusion furnace, the surface of the substrate 10 can be heated uniformly. The annealing temperature can be, for example, 300 ° C. to 800 ° C., and is preferably lower than the crystallization annealing temperature when forming the piezoelectric layer 40 described above. By performing annealing at such a temperature, the crystallinity of the piezoelectric layer 40 can be more reliably recovered to a good state. Further, the annealing may be performed in an oxygen atmosphere or in an inert gas atmosphere such as a nitrogen atmosphere.

  Next, the above-described 1. Step (5) is performed (step S406). Next, annealing (third annealing) is performed (step S407). Annealing can be performed using, for example, a diffusion furnace or an RTA apparatus. Annealing is performed, for example, for about 60 to 180 minutes when a diffusion furnace is used. By using the diffusion furnace, the surface of the substrate 10 can be heated uniformly. The annealing temperature can be, for example, 300 ° C. to 800 ° C., and is preferably lower than the crystallization annealing temperature when forming the piezoelectric layer 40 described above. By performing annealing at such a temperature, the crystallinity of the piezoelectric layer 40 can be more reliably recovered to a good state. Further, the annealing may be performed in an oxygen atmosphere or in an inert gas atmosphere such as a nitrogen atmosphere.

  Next, the above-described 1. Steps (6) and (7) are performed (steps S308 to S310). Next, annealing (second annealing) is performed (step S411). Annealing can be performed using, for example, a diffusion furnace or an RTA apparatus. Annealing is performed, for example, for about 30 to 60 minutes when a diffusion furnace is used. By using the diffusion furnace, the surface of the substrate 10 can be heated uniformly. The annealing temperature can be 450 ° C. to 600 ° C., for example, and is preferably lower than the crystallization annealing temperature when forming the piezoelectric layer 40 described above. Further, annealing is performed in an oxygen atmosphere. By heating in an oxygen atmosphere, oxygen vacancies in the piezoelectric layer 42 are compensated, and the crystallinity can be recovered to a good state. Also, the annealing may be performed in an inert gas atmosphere such as a nitrogen atmosphere.

  Next, the above-described 1. By performing the steps (8) to (13) (steps S412 to S420), an ink jet recording head can be manufactured.

  By performing the annealing in step S411, it is possible to recover the damage received by the capacitor structure 62 when the upper electrode layer 50 and the piezoelectric layer 40 are etched and when the protective film 70 is formed. Further, the oxygen deficiency in the piezoelectric layer 40 can be compensated by performing the annealing in step S407 and the annealing in step S405.

3. Experimental Example 3.1. Displacement distribution of piezoelectric element and rate of decrease of displacement The displacement distribution of piezoelectric element and the rate of decrease of displacement were investigated. A sample for measuring the amount of displacement was prepared as follows.

3.1.1. Preparation of Sample 1 First, a silicon substrate was prepared, and zirconium oxide as an elastic layer was formed on the silicon substrate by sputtering. Next, a lower electrode layer made of platinum was formed on the elastic layer by sputtering. Next, a piezoelectric layer made of PZT was formed on the lower electrode layer by a sol-gel method. Here, the crystallization annealing was performed at about 700 ° C.

  Next, an upper electrode layer made of platinum was formed on the piezoelectric layer by sputtering. Next, a photoresist having a predetermined shape was formed on the upper electrode layer, dry etching was performed using the photoresist as a mask, and the upper electrode layer and the piezoelectric layer were patterned. Next, a protective film made of aluminum oxide was formed, a photoresist having a predetermined shape was formed thereon, and dry etching was performed using the photoresist as a mask.

  Next, the silicon substrate was placed in a diffusion furnace and annealed (first anneal). Annealing was performed at 550 ° C. for 1 hour. Next, a wiring film was formed by sputtering and patterned to prepare Sample 1.

3.1.2. Preparation of Sample 2 First, a silicon substrate was prepared, and zirconium oxide as an elastic layer was formed on the silicon substrate by sputtering. Next, a lower electrode layer made of platinum was formed on the elastic layer by sputtering. Next, a piezoelectric layer made of PZT was formed on the lower electrode layer by a sol-gel method. Here, the crystallization annealing was performed at about 700 ° C.

  Next, an upper electrode layer made of platinum was formed on the piezoelectric layer by sputtering. Next, a photoresist having a predetermined shape was formed on the upper electrode layer, dry etching was performed using the photoresist as a mask, and the upper electrode layer and the piezoelectric layer were patterned. Next, a protective film made of aluminum oxide was formed. Next, the silicon substrate was placed in a diffusion furnace and annealed (second anneal). Annealing was performed at 550 ° C. for 1 hour. Next, a photoresist having a predetermined shape was formed on the protective film, and dry etching was performed using the photoresist as a mask.

  Next, a wiring film was formed by sputtering and patterned to prepare Sample 2.

3.1.3. Preparation of Sample 3 First, a silicon substrate was prepared, and zirconium oxide was formed as an elastic layer on the silicon substrate by sputtering. Next, a lower electrode layer made of platinum was formed on the elastic layer by sputtering. Next, a piezoelectric layer made of PZT was formed on the lower electrode layer by a sol-gel method. Here, the crystallization annealing was performed at about 700 ° C.

  Next, the silicon substrate was placed in a diffusion furnace and annealed (fourth anneal). Annealing was performed at 700 ° C. for 3 hours.

  Next, an upper electrode layer made of platinum was formed on the piezoelectric layer by sputtering. Next, a photoresist having a predetermined shape was formed on the upper electrode layer, dry etching was performed using the photoresist as a mask, and the upper electrode layer and the piezoelectric layer were patterned. Next, a protective film made of aluminum oxide was formed. Next, a photoresist having a predetermined shape was formed on the protective film, and dry etching was performed using the photoresist as a mask.

  Next, a wiring film was formed by sputtering and patterned to prepare Sample 3.

3.1.4. Preparation of Sample 4 First, a silicon substrate was prepared, and zirconium oxide was formed as an elastic layer on the silicon substrate by sputtering. Next, a lower electrode layer made of platinum was formed on the elastic layer by sputtering. Next, a piezoelectric layer made of PZT was formed on the lower electrode layer by a sol-gel method. Here, the crystallization annealing was performed at about 700 ° C.

  Next, an upper electrode layer made of platinum was formed on the piezoelectric layer by sputtering. Next, a photoresist having a predetermined shape was formed on the upper electrode layer, dry etching was performed using the photoresist as a mask, and the upper electrode layer and the piezoelectric layer were patterned. Next, a protective film made of aluminum oxide was formed. Next, a photoresist having a predetermined shape was formed on the protective film, and dry etching was performed using the photoresist as a mask.

  Next, a wiring film was formed by sputtering and patterned to prepare Sample 4.

3.1.5. Displacement amount distribution About the sample 1-the sample 4 produced as mentioned above, the displacement amount was measured for every position in the in-plane direction of a silicon substrate. The result is shown in FIG. In FIG. 18, the vertical axis indicates a value normalized by setting the maximum displacement amount of each sample as 1, and the horizontal axis indicates a measurement position on the substrate.

  According to FIG. 18, the displacement amount distribution of sample 1 has the highest in-plane uniformity, then the displacement amount distributions of sample 2 and sample 3 have the best in-plane uniformity, and the displacement amount distribution of sample 4 has the highest surface displacement. It was confirmed that the internal uniformity was low. According to this, it was confirmed that the in-plane uniformity of the displacement amount was most improved by performing annealing after patterning of the protective film. It was also confirmed that the in-plane uniformity of the displacement amount was improved by performing annealing after forming the protective film and after forming the piezoelectric film.

3.1.6. Decreasing rate of displacement amount With respect to Sample 1 to Sample 4, the decreasing rate of the displacement amount was measured by performing a reliability test (pulse durability test). In the reliability test, a pulse bias of + 15.5V → −2V → + 33V → + 8V → + 15.5V was applied to each sample at a frequency of 50 kHz, and the number of pulses was 5 billion, 10 billion, and 19 billion. The amount of displacement was measured at the time. From the measurement results, the rate of decrease with respect to the amount of displacement before voltage application was calculated. The result is shown in FIG.

  According to FIG. 19, the displacement rate reduction rate of sample 4 was about 6.8%, but in all of samples 1 to 3, the displacement rate reduction rate was suppressed to within 3%. Therefore, it was confirmed that by performing the annealing, the rate of decrease in the displacement amount of the piezoelectric element was suppressed and the reliability was improved.

3.2. Hysteresis characteristics for each sample 3.1. The hysteresis characteristics were measured for Sample 1, Sample 2, and Sample 4 produced in the above. TVS curves showing the measurement results are shown in FIGS. FIG. 20 shows the TVS curve of Sample 1. FIG. 21 shows the TVS curve of Sample 2. 22 to 24 show the TVS curves of Sample 4, FIG. 22 shows the measurement results after etching the upper electrode, FIG. 23 shows the measurement results after forming the protective film, and FIG. 24 shows the results after etching the protective film. It is a measurement result.

  22 to 24, it can be seen that a double peak occurs due to the subsequent process after the etching of the upper electrode, and the characteristics are gradually deteriorated. On the other hand, according to FIG. 20 and FIG. 21, it was confirmed that the double peak was eliminated in the TVS curves of sample 1 and sample 2 that were annealed, and the characteristics were recovered.

3.3. Annealing Temperature Dependence of Hysteresis Characteristics Sample 5 was prepared and annealed at a plurality of temperatures as follows, and the hysteresis characteristics were examined.

  First, a silicon substrate was prepared, and zirconium oxide as an elastic layer was formed on the silicon substrate by sputtering. Next, a lower electrode layer made of platinum was formed on the elastic layer by sputtering. Next, a piezoelectric layer made of PZT was formed on the lower electrode layer by a sol-gel method. Here, the crystallization annealing was performed at about 700 ° C.

  Next, an upper electrode layer made of platinum was formed on the piezoelectric layer by sputtering. Next, a photoresist having a predetermined shape was formed on the upper electrode layer, dry etching was performed using the photoresist as a mask, and the upper electrode layer and the piezoelectric layer were patterned.

  Next, the silicon substrate was placed in a diffusion furnace and annealed (third anneal). Annealing was performed at 550 ° C., 600 ° C., 650 ° C., 700 ° C., and 750 ° C. for 5 minutes, respectively. Samples 5 to 9 are shown, and hysteresis characteristics before and after each annealing are shown in FIGS.

  According to FIG. 25 to FIG. 29, it was confirmed that the hysteresis characteristics of sample 5 annealed at 550 ° C. were improved by annealing. On the other hand, at the annealing temperature of 650 ° C. or higher, no improvement in hysteresis characteristics was observed. Therefore, in order to improve the characteristics, it was confirmed that an annealing temperature of 600 ° C. or lower is preferable, and about 550 ° C. is more preferable.

4). Next, the overall structure of an ink jet recording head using the piezoelectric element 100 will be described. 30 is a side sectional view showing a schematic configuration of the ink jet recording head, and FIG. 31 is an exploded perspective view of the ink jet recording head. In addition, FIG. 31 is shown upside down from the state normally used.

  As shown in FIG. 30, the ink jet recording head (hereinafter also referred to as “head”) 500 includes a head main body 542 and a piezoelectric portion 540 provided on the head main body 542. 30 corresponds to the lower electrode layer 30, the piezoelectric layer 42, and the upper electrode layer 52 in the piezoelectric element 100. The piezoelectric unit 540 illustrated in FIG. In the ink jet recording head according to the present embodiment, the piezoelectric element 100 can function as a piezoelectric actuator. A piezoelectric actuator is an element having a function of moving a certain substance, that is, an element that generates a mechanical strain by applying a voltage.

  Further, the oxide layer 14 and the elastic body layer 20 in the piezoelectric element 100 correspond to the elastic film 550 in FIG. The substrate 10 constitutes a main part of the head main body 542.

  That is, the head 500 includes a nozzle plate 510, an ink chamber substrate 520, an elastic film 550, and a piezoelectric part (vibration source) 540 bonded to the elastic film 550, as shown in FIG. It is housed and configured. The head 500 constitutes an on-demand piezo jet head.

  The nozzle plate 510 is made of, for example, a stainless steel rolling plate or the like, and has a large number of nozzles 511 for discharging ink droplets formed in a line. The pitch between these nozzles 511 is appropriately set according to the printing accuracy.

  An ink chamber substrate 520 is fixed (fixed) to the nozzle plate 510. The ink chamber substrate 520 is formed by the silicon substrate 12 described above. The ink chamber substrate 520 includes a plurality of cavities (ink cavities) 521, a reservoir 523, and supply ports 524 formed by a nozzle plate 510, side walls (partition walls) 522, and an elastic film 550 described later. It is. The reservoir 523 temporarily stores ink supplied from the ink cartridge 631 (see FIG. 23). Ink is supplied from the reservoir 523 to each cavity 521 through the supply port 524.

  As shown in FIGS. 30 and 31, the cavity 521 is disposed corresponding to each nozzle 511. The cavities 521 each have a variable volume due to vibration of an elastic film 550 described later. The cavity 521 is configured to eject ink by this volume change.

  An elastic film 550 is disposed on the side of the ink chamber substrate 520 opposite to the nozzle plate 510. Further, a plurality of piezoelectric portions 540 are provided on the side of the elastic film 550 opposite to the ink chamber substrate 520. As shown in FIG. 31, a communication hole 531 is formed at a predetermined position of the elastic film 550 so as to penetrate in the thickness direction of the elastic film 550. Ink is supplied from an ink cartridge 631 to be described later to the reservoir 523 through the communication hole 531.

  Each piezoelectric unit 540 is electrically connected to a piezoelectric element driving circuit described later, and is configured to operate (vibrate, deform) based on a signal from the piezoelectric element driving circuit. That is, each piezoelectric unit 540 functions as a vibration source (head actuator). The elastic film 550 vibrates (deflection) by the vibration (deflection) of the piezoelectric part 540 and functions to instantaneously increase the internal pressure of the cavity 521.

  The base 560 is made of, for example, various resin materials, various metal materials, or the like. As shown in FIG. 31, the ink chamber substrate 520 is fixed and supported on the base 560.

  According to the ink jet recording head 500 according to the present embodiment, as described above, since cracks are unlikely to occur in the piezoelectric portion 540, the reliability is high, the piezoelectric characteristics are good, and efficient ink ejection is achieved. It is possible. Therefore, it is possible to increase the density of the nozzles 511, thereby enabling high-density printing and high-speed printing. Furthermore, the entire head can be reduced in size.

5. Inkjet Printer Next, an inkjet printer equipped with the above-described inkjet recording head 500 will be described. FIG. 32 is a schematic configuration diagram showing an embodiment in which the inkjet printer 600 of the present invention is applied to a general printer that prints on paper or the like. In the following description, the upper side in FIG. 32 is referred to as “upper part” and the lower side is referred to as “lower part”.

  The ink jet printer 600 includes an apparatus main body 620, has a tray 621 for placing the recording paper P on the upper rear side, has a discharge port 622 for discharging the recording paper P on the lower front, and has an operation panel 670 on the upper surface. Have

  Inside the apparatus main body 620, there are mainly a printing apparatus 640 provided with a reciprocating head unit 630, a paper feeding apparatus 650 for feeding the recording paper P one by one to the printing apparatus 640, the printing apparatus 640 and the paper feeding apparatus. A control unit 660 for controlling the 650 is provided.

  The printing apparatus 640 includes a head unit 630, a carriage motor 641 serving as a drive source for the head unit 630, and a reciprocating mechanism 642 that receives the rotation of the carriage motor 641 to reciprocate the head unit 630.

  The head unit 630 includes an ink jet recording head 500 provided with the above-described many nozzles 511, an ink cartridge 631 that supplies ink to the ink jet recording head 500, an ink jet recording head 500, and an ink cartridge 631 at a lower portion thereof. And a carriage 632 mounted thereon.

  The reciprocating mechanism 642 includes a carriage guide shaft 643 whose both ends are supported by a frame (not shown), and a timing belt 644 extending in parallel with the carriage guide shaft 643. The carriage 632 is supported by the carriage guide shaft 643 so as to reciprocate and is fixed to a part of the timing belt 644. When the timing belt 644 travels forward and backward through a pulley by the operation of the carriage motor 641, the head unit 630 reciprocates while being guided by the carriage guide shaft 643. During this reciprocation, ink is appropriately discharged from the ink jet recording head 500 and printing on the recording paper P is performed.

  The sheet feeding device 650 includes a sheet feeding motor 651 serving as a driving source thereof, and a sheet feeding roller 652 that rotates by the operation of the sheet feeding motor 651. The paper feed roller 652 includes a driven roller 652 a and a drive roller 652 b that are opposed to each other across the feeding path (recording paper P) of the recording paper P, and the driving roller 652 b is connected to the paper feeding motor 651. Has been.

  The ink jet printer 600 according to the present embodiment includes the ink jet recording head 500 that is highly reliable, has high performance, and can increase the density of the nozzles. Therefore, high density printing and high speed printing are possible.

  The ink jet printer 600 of the present invention can also be used as a droplet discharge device used industrially. In that case, as the ink to be ejected (liquid material), various functional materials can be used by adjusting them to an appropriate viscosity with a solvent or a dispersion medium.

  6). Although the embodiments of the present invention have been described in detail as described above, those skilled in the art will readily understand that many modifications are possible without substantially departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention.

  In addition to the actuator, the ink jet recording head, and the ink jet printer, the piezoelectric element according to the above-described embodiment includes, for example, a gyro element such as a gyro sensor, an FBAR (film bulk acoustic resonator) type, an SMR (solid mounted resonator) type, and the like. The present invention can be applied to a BAW (bulk acoustic wave) filter, an ultrasonic motor, and the like. Since the piezoelectric element according to the embodiment of the present invention has good piezoelectric characteristics and high reliability as described above, it can be suitably applied to various applications.

It is a flowchart which shows the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is sectional drawing which shows typically the manufacturing method of the piezoelectric element concerning this Embodiment. It is a flowchart which shows the manufacturing method of the piezoelectric element concerning a 1st modification. It is a flowchart which shows the manufacturing method of the piezoelectric element concerning a 2nd modification. It is a flowchart which shows the manufacturing method of the piezoelectric element concerning a 3rd modification. It is a figure which shows the displacement distribution of the piezoelectric element concerning an experiment example. It is a figure which shows the displacement amount fall rate of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. It is a figure which shows the hysteresis characteristic of the piezoelectric element concerning an experiment example. 1 is a schematic configuration diagram of an ink jet recording head according to an embodiment. 1 is an exploded perspective view of an ink jet recording head according to an embodiment. It is a schematic block diagram of the inkjet printer concerning this Embodiment.

Explanation of symbols

10 substrate, 12 silicon layer, 14 oxide layer, 20 elastic layer, 30 lower electrode layer, 32 lower electrode layer, 40 piezoelectric layer, 42 piezoelectric layer, 50 upper electrode layer, 52 upper electrode layer, 62 capacitor structure Part, 70 protective film, 72 protective film, 80 wiring film, 82 wiring film, 90 sealing plate, 100 piezoelectric element, 500 inkjet recording head, 510 nozzle plate, 511 nozzle, 520 ink chamber substrate, 521 cavity, 522 Side wall, 523 reservoir, 524 supply port, 531 communication hole, 540 piezoelectric actuator, 542 head main body, 550 elastic plate, 560 substrate, 600 ink jet printer, 620 apparatus main body, 621 tray, 622 discharge port, 630 head unit, 631 ink cartridge 632 carriage, 40 printing apparatus, 641 a carriage motor 642 reciprocating mechanism, 643 a carriage guide shaft, 644 a timing belt, 650 sheet feeding apparatus, 651 a sheet feeding motor, 652 feed roller, 660 control unit, 670 operation panel

Claims (6)

(A) forming a first electrode above the substrate side;
(B) forming a piezoelectric layer above the first electrode;
(C) forming a second electrode above the piezoelectric layer;
(D) patterning at least a part of the second electrode and the piezoelectric layer to form a capacitor structure having the first electrode, the piezoelectric layer, and the second electrode;
(E) after the step (d), forming a protective film that covers at least a part of the capacitor structure;
(F) a step of performing a first annealing after the step (e);
(G) forming a wiring film electrically connected to the upper electrode;
Only including,
The step (e)
(E1) forming a protective film;
(E2) patterning the protective film;
Between the steps (e1) and (e2),
Further comprising performing a second anneal,
Between the steps (c) and (d),
Further comprising performing a third anneal,
The step (b)
Applying a precursor solution of the piezoelectric layer above the first electrode;
Performing crystallization annealing of the precursor solution;
Have
Between the steps (b) and (c),
Further comprising performing a fourth anneal,
The method of manufacturing a piezoelectric element, wherein the first annealing, the second annealing, the third annealing, and the fourth annealing are performed in an oxygen atmosphere using a diffusion furnace . In claim 1 ,
The temperature of the first annealing before Symbol step (f) is lower than the temperature of the crystallization annealing, the method for manufacturing a piezoelectric element. In claim 1 ,
Before SL temperature of the second annealing is lower than the temperature of the crystallization annealing, the method for manufacturing a piezoelectric element. In any one of Claims 1 thru | or 3,
The method of manufacturing a piezoelectric element, wherein a temperature of the fourth annealing is 300 ° C. to 800 ° C. In any one of Claims 1 thru | or 4,
The method for manufacturing a piezoelectric element, wherein a temperature of the third annealing is 300 ° C. to 800 ° C. In any one of Claims 1 thru | or 5,
The method of manufacturing a piezoelectric element, wherein a temperature of the second annealing is 450 ° C. to 600 ° C.