JPH10139594A - Piezoelectric thin film, its production and ink jet recording head using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the piezoelectric thin film whose piezoelectric strain constant value is not reduced even at the time of increasing the thickness of the thin film and also to provide the production of the thin film. SOLUTION: This piezoelectric thin film 21 consists of a base layer(s) 14 formed from a three-component system piezoelectric material and a member layer(s) 13 formed from a two-component system piezoelectric material having a lower crystallization temp. than that of the base layer's) 14. Therefore, the crystal properties of the piezoelectric thin film 21 as a whole at the time of increasing the film thickness, are improved and the reduction in piezoelectric constant value of the thin film 21 having an increased thickness is inhibited from occurring. Further, the piezoelectric film 21 having an increased thickness is produced by many times forming coating layers of the above piezoelectric materials with a sol-gel method and annealing/crystallizing these piezoelectric material coating layers all together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric thin film element used as an actuator in an ink jet recording apparatus or the like.

[0002]

2. Description of the Related Art Piezoelectric and ferroelectric thin films represented by PZT can be formed by a sputtering method, a sol-gel method, a CVD method, a laser ablation method, or the like. In order to increase the film thickness, the deposition time for forming the film is increased or the film formation is repeated a plurality of times. In order to obtain a perovskite structure, annealing is usually performed in an oxygen atmosphere at 500 to 700 ° C.

In particular, the sol-gel method has excellent composition controllability, and a thin film can be easily obtained by repeating spin coating and baking. Patterning using a photo-etching process is possible, and device formation is easy. Further, an ink jet recording head using the piezoelectric thin film element manufactured as described above has been proposed. (Tokuhei 5-504740)
When the thickness of the two-component piezoelectric thin film is increased by the sol-gel method, there is a problem that the piezoelectric strain constant tends to decrease due to the deterioration of crystallinity. Therefore, for the purpose of improving the piezoelectric strain constant at the time of a thick film, a method of manufacturing a piezoelectric thin film having a structure having a partial layer made of PT having a lower crystallization temperature has been implemented for a two-component piezoelectric material.

[0004]

However, in increasing the thickness of a three-component piezoelectric thin film by the sol-gel method, a partial layer made of a material having a low crystallization temperature, which is performed in the case of a two-component piezoelectric thin film, is used. No method has been implemented to produce a piezoelectric thin film having a structure having Therefore, the problem regarding the reduction of the piezoelectric strain constant has not been solved yet.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a three-component piezoelectric element having a partial layer made of a two-component piezoelectric material having a lower crystallization temperature. It is an object of the present invention to provide a three-component piezoelectric thin-film element which manufactures a body thin film and suppresses a decrease in piezoelectric strain constant when the film is thick, and a method for manufacturing the same. In addition, an ink jet recording head using the piezoelectric thin film manufactured as described above as a vibrator is proposed.

[0006]

Means for Solving the Problems To solve the above problems, the piezoelectric thin film of the present invention has the following features.
A structure composed of a three-component piezoelectric material formed of Z and PT and having a two-component material formed of PZ and PT in a partial layer; and (2) a plurality of partial layers formed in the piezoelectric thin film. And (3) the composition ratio of PZ and PT forming the partial layer is 0.3 or more and 0.7 or less.

Further, the method of manufacturing a piezoelectric thin film of the present invention
(1) In the cross-sectional view of the piezoelectric thin film shown in FIGS.
A platinum electrode 12 is formed on a silicon substrate 11, a multilayer thin film formed from a partial layer 13 and a mother layer 14 is formed thereon by using a sol-gel method, and annealed and crystallized collectively to form a piezoelectric film. FIG. 1 shows a case where the mother layer 14 is formed on the lowermost partial layer 13.
FIG. 2 shows a case where the partial layer 13 is formed in the middle of the mother layer 14, and FIG. 3 shows a case where the partial layer 13 is formed on the uppermost layer of the mother layer 14. (3) FIG. 4 shows the piezoelectric thin film 21.
Forming a plurality of partial layers at arbitrary layer positions in the
(4) Repeating the above manufacturing process, laminating the piezoelectric material a plurality of times to increase the thickness, and (5) annealing at 600 ° C.
The crystallization is performed in a temperature range of up to 900 ° C.

Furthermore, an ink jet recording head of the present invention is characterized in that the piezoelectric thin film of the present invention is used as a vibrator.

[0009]

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

(Example 1) 0.105 mol of lead acetate, 0.045 mol of zirconium acetylacetonate, 0.005 mol of magnesium acetate and 30 ml of acetic acid were dissolved by heating to 100 ° C. Cool to room temperature,
0.040 mol of titanium tetraisopropoxide and 0.010 mol of pentaethoxyniobium
Dissolved in milliliter and added. After stabilizing by adding 30 ml of acetylacetone, polyethylene glycol was added in an amount of 30% by weight to the metal oxide in the sol.
The mixture was added and stirred well to obtain a homogeneous three-component mother layer sol of PMN, PT and PZ.

Separately, 0.105 mol of lead acetate, 0.050 mol of zirconium acetylacetonate and 30 mol of
Milliliter of acetic acid was dissolved by heating to 100 ° C. After cooling to room temperature, 0.050 mol of titanium tetraisopropoxide was dissolved in 50 ml of ethyl cerasolve and added. After 30 ml of acetylacetone was added to stabilize, 30% by weight of polyethylene glycol was added to the metal oxide in the sol, and the mixture was thoroughly stirred to obtain a homogeneous PZT binary partial layer sol.

FIG. 1 is a sectional view schematically showing a piezoelectric thin film. Twelve platinum electrodes were formed on the eleventh silicon substrate by a sputtering method, and the prepared partial layer sol was applied thereon by spin coating and calcined at 400 ° C. An amorphous partial layer 13 having a thickness of 0.3 μm without cracking
Could be formed. Further, the application of the sol of the mother layer and the preliminary baking at 400 ° C. were repeated five times to form the mother layer 14 having a thickness of 1.5 μm. Next, the substrate was heated to 850 ° C. in an oxygen atmosphere using RTA (Rapid Thermal Annealing) and held for 1 minute for annealing. A 1.2 μm thick piezoelectric thin film 21 was obtained.
An aluminum electrode was formed by a vapor deposition method on the piezoelectric thin film 21 where a sharp and strong peak of perovskite type crystal was detected by X-ray analysis, and after polarization, the physical properties were measured. The relative dielectric constant was 2000 and the piezoelectric strain constant was 200 pC / N. Characteristics. Although the dielectric constant was not extremely high, a large piezoelectric strain constant was obtained because of the high electromechanical coupling coefficient.

FIG. 6 is a sectional view schematically showing a concept when the piezoelectric thin film element produced by this manufacturing method is used in an ink jet recording apparatus. A vibration plate 32 of silicon nitride was formed on a silicon wafer 31 by a sputtering method, and a lower electrode 33 and a piezoelectric thin film 34 were formed by the above-described method. The piezoelectric thin film was patterned into a width of 0.2 mm and a length of 4 mm by photoetching, and a groove having a width of 0.3 mm was formed in the silicon wafer by anisotropic etching. After forming the gold upper electrode 35, it was joined to a glass second substrate 36 to form an ink channel 37. When the ink jet head was assembled by cutting the entire substrate and the ink was ejected, a sufficient ejection force was obtained. When printing was performed by incorporating the ink jet recording apparatus in an ink jet recording apparatus, good printing quality was obtained. High definition can be achieved by using photoetching, and cost can be reduced because a large number of elements can be obtained from one substrate. The production stability and the reproducibility of the characteristics were also very excellent.

(Examples 2 to 9) In the same manner as in Example 1,
A sol of a ternary base layer of PMN, PT and PZ was prepared.

Separately, the addition ratios of zirconium acetylacetonate and titanium tetraisopropoxide were adjusted to prepare eight kinds of PZT binary partial layer sols having different PT / PZ composition ratios.

A piezoelectric thin film having the structure shown in FIG. 1 was manufactured in the same manner as in Example 1. First, 12 platinum electrodes were formed on a 11 silicon substrate by a sputtering method, and the sol of a partial layer adjusted to each composition ratio was applied thereon by spin coating.
Was calcined. 0.3μm without crack
Thus, an amorphous partial layer 13 having a film thickness of 5 mm was formed. Further, the application of the mother layer sol and the temporary baking at 400 ° C. were repeated 5 times,
A mother layer 14 having a thickness of μm was formed. Next, the substrate was heated to 850 ° C. in an oxygen atmosphere using RTA, held for 1 minute, and annealed. A 1.2 μm thick piezoelectric thin film 21 was obtained. An aluminum electrode is formed on the piezoelectric thin film 21 by a vapor deposition method,
Table 1 shows the results of measuring the electrical characteristics after the polarization.

[0017]

[Table 1]

As is clear from Table 1, the composition ratio P of the partial layer
When Z / PT was 0.3 or more and 0.7 or less, high piezoelectric characteristics were obtained.

Comparative Example 1 In the same manner as in Example 1, PM
A sol of a three-component base layer of N, PT, and PZ was prepared.

Separately, a PT single-component partial layer sol was prepared as a partial layer.

A piezoelectric thin film having the structure shown in FIG. 1 was manufactured in the same manner as in Example 1. First, 12 platinum electrodes were formed on a 11 silicon substrate by a sputtering method, and the sol of a partial layer adjusted to each composition ratio was applied thereon by spin coating.
Was calcined. 0.3μm without crack
Thus, an amorphous partial layer 13 having a film thickness of 5 mm was formed. Further, the application of the mother layer sol and the temporary baking at 400 ° C. were repeated 5 times,
A mother layer 14 having a thickness of μm was formed. Next, the substrate was heated to 850 ° C. in an oxygen atmosphere using RTA, held for 1 minute, and annealed. A 1.2 μm thick piezoelectric thin film 21 was obtained.

An aluminum electrode was formed on the piezoelectric thin film 21 by vapor deposition, and after polarization, the electrical characteristics were measured. The results were a relative dielectric constant of 300 and a piezoelectric strain constant of 10 pC / N. As a result, no higher piezoelectric characteristics were obtained in the case of the PT one-component partial layer than in the case of the PZT two-component partial layer.

(Comparative Example 2) In the same manner as in Example 1, PM
A sol of a three-component base layer of N, PT, and PZ was prepared.

First, a platinum electrode was formed on a silicon substrate by sputtering, and the application of the sol of the mother layer and the preliminary baking at 400 ° C. were repeated six times to form a mother layer having a thickness of 1.8 μm. Next, the substrate was heated to 850 ° C. in an oxygen atmosphere using RTA, held for 1 minute, and annealed. A 1.2 μm thick piezoelectric thin film was obtained. An aluminum electrode was formed on the piezoelectric thin film by a vapor deposition method, and after polarization, the electrical characteristics were measured. As a result, the relative dielectric constant was 1500 and the piezoelectric strain constant was 60 pC.
/ N was obtained. This result shows the effect of forming a PZT binary partial layer.

(Embodiment 10) In the same manner as in Embodiment 1, P
A sol of a three-component base layer of MN, PT, and PZ and a sol of a partial layer of a two-component PZT were prepared.

FIG. 2 is a sectional view schematically showing a piezoelectric thin film. Twelve platinum electrodes were formed on the eleventh silicon substrate by sputtering, and the application of the sol of the mother layer and the preliminary baking at 400 ° C. were repeated three times to form the mother layer 14 having a thickness of 0.9 μm. Further, the sol of the partial layer was applied and calcined at 400 ° C. to form a partial layer 13 having a thickness of 0.3 μm. Further, the application of the sol of the mother layer and the preliminary baking at 400 ° C. were repeated three times to form the mother layer 14 having a thickness of 0.9 μm. Then RTA
Was heated to 850 ° C. in an oxygen atmosphere, and kept for 1 minute for annealing. A piezoelectric thin film 21 having a thickness of 1.4 μm was obtained.

An aluminum electrode was formed on the piezoelectric thin film 21 by vapor deposition, and after polarization, the electrical characteristics were measured. The relative dielectric constant was 1800 and the piezoelectric strain constant was 180 pC / N.
And showed excellent characteristics.

(Embodiment 11) In the same manner as in Embodiment 1, P
A sol of a three-component base layer of MN, PT, and PZ and a sol of a partial layer of a two-component PZT were prepared.

FIG. 3 is a sectional view schematically showing a piezoelectric thin film. Twelve platinum electrodes were formed on the eleventh silicon substrate by sputtering, and the application of the sol of the mother layer and the preliminary baking at 400 ° C. were repeated five times to form the mother layer 14 having a thickness of 1.5 μm. Further, a partial layer 13 having a thickness of 0.3 μm was formed thereon by applying a sol of the partial layer and performing preliminary baking at 400 ° C.
Next, it is heated to 850 ° C. in an oxygen atmosphere using RTA,
Hold for 10 minutes and anneal. A 1.2 μm thick piezoelectric thin film 21 was obtained.

An aluminum electrode was formed on the piezoelectric thin film 21 by vapor deposition, and after polarization, the electrical characteristics were measured. As a result, the relative dielectric constant was 1800, and the piezoelectric strain constant was 160 pC / N.
And showed excellent characteristics.

(Embodiment 12) As in Embodiment 1, P
A sol of a three-component base layer of MN, PT, and PZ and a sol of a partial layer of a two-component PZT were prepared.

FIG. 4 is a sectional view schematically showing a piezoelectric thin film. 12 platinum electrodes are formed by sputtering on 11 silicon substrates, and a partial layer sol is applied thereon and 400 ° C.
And forming a partial layer 13 having a thickness of 0.3 μm,
Further, sol application of the mother layer and preliminary baking at 400 ° C.
Each time, a mother layer 14 having a thickness of 0.9 μm was formed. Similarly, a 0.3 μm thick partial layer 13 and 0.9 μm
An m-thick mother layer 14 was formed. Next, the substrate was heated to 850 ° C. in an oxygen atmosphere using RTA, held for 1 minute, and annealed. A 1.6 μm thick piezoelectric thin film 21 was obtained.

An aluminum electrode was formed on the piezoelectric thin film 21 by vapor deposition, and after polarization, the electrical characteristics were measured. The relative dielectric constant was 1700, and the piezoelectric strain constant was 190 pC / N.
And showed excellent characteristics.

(Embodiment 13) In the same manner as in Embodiment 1, P
A sol of a three-component base layer of MN, PT, and PZ and a sol of a partial layer of a two-component PZT were prepared.

A platinum electrode was formed on a silicon substrate by a sputtering method.
A 2 μm thick piezoelectric thin film was formed. Further, the same manufacturing method was repeated twice thereon, and a 2.4 μm-thick piezoelectric thin film was laminated to form a total 3.6 μm-thick piezoelectric thin film.

An aluminum electrode was formed on the piezoelectric thin film by vapor deposition, and after polarization, the electrical characteristics were measured. The relative dielectric constant was 1600 and the piezoelectric strain constant was 180 pC / N.
And showed excellent characteristics.

(Examples 14 to 24) 0.105 mol of lead acetate, 0.042 mol of zirconium acetylacetonate, 0.007 mol of magnesium acetate and 30 ml of acetic acid were dissolved by heating to 100 ° C. After cooling to room temperature, 0.038 mol of titanium tetraisopropoxide and 0.013 mol of pentaethoxyniobium were dissolved in 50 ml of ethyl cerasolve and added. After 30 ml of acetylacetone was added to stabilize, 30% by weight of polyethylene glycol was added to the metal oxide in the sol, and the mixture was thoroughly stirred to obtain homogeneous PMN and P.
The sol was a ternary base layer of T and PZ.

In the same manner as in Example 1, a PZT binary partial layer sol was prepared.

A platinum electrode was formed on a silicon substrate by sputtering, and one partial layer and five mother layers were laminated by calcination at 400 ° C. in the same manner as described in Example 1. Next, only the annealing process temperature was changed in 11 steps to form a 1.2 μm thick piezoelectric thin film.

An aluminum electrode was formed on the piezoelectric thin film by vapor deposition, and after polarization, the electrical characteristics were measured.
Shown in

[0041]

[Table 2]

As is clear from Table 2, the annealing temperature of 60
High piezoelectric characteristics were obtained at 0 ° C to 900 ° C.

[0043]

As described above, the piezoelectric thin film of the present invention has a high dielectric constant and a high piezoelectric strain constant which can be widely applied. Further, the method of manufacturing a piezoelectric thin film of the present invention prevents a decrease in the piezoelectric constant that occurs when the film is thickened by the sol-gel method, and has a high dielectric constant and a high piezoelectric strain constant even in the case of a thick film. Could be provided. In addition, it was easy to miniaturize by photoetching, and it was possible to provide an ink jet recording head capable of performing high-definition printing using the piezoelectric thin film of the present invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a method for manufacturing a piezoelectric thin film of the present invention.

FIG. 2 is a cross-sectional view schematically illustrating a method for manufacturing a piezoelectric thin film of the present invention.

FIG. 3 is a cross-sectional view schematically illustrating a method for manufacturing a piezoelectric thin film according to the present invention.

FIG. 4 is a cross-sectional view schematically illustrating a method for manufacturing a piezoelectric thin film of the present invention.

FIG. 5 is a three-component composition diagram showing a preferred composition of a piezoelectric thin film according to the present invention.

FIG. 6 is a cross-sectional view schematically illustrating a concept of an ink jet recording head used in the ink jet recording apparatus according to the first embodiment of the present invention.

[Explanation of symbols]

 11 Silicon substrate 12 シ リ コ ン Platinum electrode 13 部分 Partial layer 14 ‥‥‥ Base layer 21 ‥‥‥ Piezoelectric thin film 31 シ リ コ ン Silicon substrate 32 振動 Vibrating plate 33 ３４ Lower electrode 34 ‥‥‥ Piezoelectric thin film 35 ‥‥‥ Upper electrode 36 第二 Second substrate 37 イ ン ク Ink flow path

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 41/187 H01L 41/22 Z 41/22

Claims (8)

[Claims] 1. A base layer comprising lead magnesium niobate (hereinafter referred to as “PMN”) and lead zirconate (hereinafter referred to as “PN”).
Z ") and lead titanate (hereinafter, referred to as" PT "), and is made of a ternary piezoelectric material. PZ and PT are used for partial layers such as a base layer, an intermediate layer, and a surface layer of a mother layer. The lead zirconate titanate (hereinafter referred to as “P
ZT)), a piezoelectric thin film having a structure having a binary material. 2. A piezoelectric thin film, wherein a plurality of partial layers according to claim 1 are formed in the piezoelectric thin film. 3. The ternary piezoelectric material according to claim 1, wherein the composition is xPb (Mg _1/3 N).
b _2/3 ) -yPbZrO ₃ -zPbTiO ₃ (x, y, z
Represents a molar ratio, is composed of a ternary piezoelectric material represented by x + y + z = 1), and is within a composition range of A, B, C, and D4 points shown below in the ternary composition diagram of this equation. A piezoelectric thin film, characterized in that: A (x = 0.05, y = 0.40, z = 0.55) B (x = 0.05, y = 0.55, z = 0.40) C (x = 0.25, y = 0.30, z = 0.30) D (x = 0.25, y = 0.45, z = 0.30) 4. The partial layer according to claim 1, wherein the composition ratio (PZ / PT) of PZ and PT forming the two-component piezoelectric material is 0.3 or more and 0.7 or less. Piezoelectric thin film. 5. In the process of producing the piezoelectric thin film according to claim 1 by a sol-gel method, a base layer made of a three-component piezoelectric material and a partial layer made of a two-component piezoelectric material are used. Anneal the formed multilayer film at once,
A method for producing a piezoelectric thin film, characterized by crystallizing. 6. A method of manufacturing a piezoelectric thin film, comprising laminating the piezoelectric thin film manufactured by the method of claim 5 a plurality of times. 7. The method for manufacturing a piezoelectric thin film according to claim 5, wherein the annealing is performed in a temperature range of 600 ° C. to 900 ° C. 8. An ink jet recording head using the piezoelectric thin film according to claim 1 as a vibrator.