Abstract:
A method of forming a pattern of an inorganic material film, which method is more versatile, easy, and practical. The method includes the steps of: (a) forming a sacrifice layer having a pattern on a substrate by employing a material having a different thermal expansion coefficient from that of an inorganic material of the inorganic material film; (b) forming an inorganic material layer on the substrate, on which the sacrifice layer has been formed, at a predetermined deposition temperature by employing the inorganic material; (c) lowering a temperature of at least the inorganic material layer to produce cracks in the inorganic material layer formed on the sacrifice layer; and (d) removing the sacrifice layer and the inorganic material layer formed thereon.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method of forming a pattern of an inorganic material film, and specifically, to a method of forming a pattern of an inorganic material film having functionality such as piezoelectric ceramics to be used in micro devices so called micro electrical mechanical systems (MEMS). Further, the present invention relates to a structure containing a pattern of an inorganic material film formed by using such a method. 
         [0003]    2. Description of a Related Art 
         [0004]    In recent years, research and development of micro electro mechanical systems (MEMS) applying semiconductor manufacturing processes have been increasingly made. Among the systems, the piezoelectric MEMS using a piezoelectric film as a functional film attracts attention as a high-power actuator, and is employed for micropumps, micro-cantilevers, micro ultrasonic transducers, and so on. Here, the functional film refers to a main part (typically, a layer sandwiched between electrodes) that exerts a function of an element like a dielectric film in a multilayered capacitor and a piezoelectric film in a piezoelectric actuator. 
         [0005]    In the MEMS, it is important to finely pattern-forming the functional film. However, conventionally, for functional films having a thickness of about 5 μm or more, there are not many appropriate fine patterning methods and appropriate materials to be employed therein. For example, the etching method or the ion beam method has disadvantages that the substrate and surrounding elements are damaged, the process time is long, and the manufacturing cost is high, and therefore, the application to pattern-forming of the functional film is not so practical. Further, although the liftoff method is higher in general versatility because the material dependence is lower than that of the etching method, the photoresist generally used as a sacrifice layer in the liftoff method deforms or burns dry at about 150° C., and the method is not applicable to the case where the process temperature (deposition temperature) becomes higher then 150° C. 
         [0006]    In the liftoff method, not only the photoresist but also silicon oxide (SiO 2 ), polysilicon, aluminum (Al), and so on are used as the sacrifice layer, and in such a case, the constraint on the deposition temperature is eased. However, the hydrofluoric acid used when removing silicon oxide and the acid or alkali solution used when removing aluminum may cause damage to the functional film. Further, since the xenon fluoride (XeF 2 ) gas used when removing polysilicon is expensive, the manufacturing cost rises. Furthermore, when the functional film is thicker than the sacrifice layer, the etchant penetration is blocked by the functional film and hard to reach the sacrifice layer, and thus, the removal of the sacrifice layer is difficult. 
         [0007]    As a related technology, Japanese Patent Application Publication JP-P2001-347499A discloses a method of manufacturing a microdevice including the steps of forming a die by recessing a groove or pore pattern deeper than a desired functional material layer on a silicon layer, depositing a functional material in the grooves or pores of the pattern of the die in a thinner thickness than that of the silicon layer, obtaining a pattern of the functional material layer by removing the die. That is, in JP-P2001-347499A, the thickness of the sacrifice layer (Si layer) is slightly thicker than the functional film (PZT layer), and thus, the selective etching of the sacrifice layer with the etching gas is promoted through the space formed by the level difference between the films (paragraph 0027). 
         [0008]    However, when the sacrifice layer is made thicker, the functional film may be affected by the stress of the sacrifice layer. Further, the longer time is required for the deposition and removal processes of the sacrifice layer, and as a result, the manufacturing cost increases. Furthermore, JP-P2001-347499A is not so practical because the photoresist and the organic compound film with poor heat resistance and silicon requiring an expensive etching gas such as xenon fluoride are used for the sacrifice layer. 
         [0009]    On the other hand, Japanese Patent Application Publication JP-P2004-282514A discloses formation of a piezoelectric thin film resonator having an air-gap acoustic insulation structure on a semiconductor integrated circuit by using germanium (Ge) as a material of a sacrifice layer and etching the sacrifice layer to remove it by using a hydrogen peroxide (H 2 O 2 ) solution, in order to form the air-gap acoustic insulation structure without property degradation due to damage on a CMOS circuit. However, when germanium is used for the sacrifice layer, some design ideas of forming a level difference on the substrate or the like is required for ensuring that the etchant reaches the sacrifice layer. 
       SUMMARY OF THE INVENTION 
       [0010]    In view of the above-mentioned problems, a purpose of the present invention is to provide a simple and practical method of forming a pattern of an inorganic material film, and a structure containing a pattern of an inorganic material film formed by using such a method. 
         [0011]    In order to attain the above-mentioned purpose, a method of forming a pattern of an inorganic material film according to one aspect of the present invention includes the steps of: (a) forming a sacrifice layer having a pattern on a substrate by employing a material having a different thermal expansion coefficient from that of an inorganic material of the inorganic material film; (b) forming an inorganic material layer on the substrate, on which the sacrifice layer has been formed, at a predetermined deposition temperature by employing the inorganic material; (c) lowering a temperature of at least the inorganic material layer to produce cracks in the inorganic material layer formed on the sacrifice layer; and (d) removing the sacrifice layer and the inorganic material layer formed thereon. 
         [0012]    Further, a structure containing a pattern of an inorganic material film according to one aspect of the present invention includes: a substrate; and a pattern of an inorganic material film formed by forming a sacrifice layer having a pattern on the substrate by employing a material having a different thermal expansion coefficient from that of an inorganic material of the inorganic material film, forming an inorganic material layer thereon at a predetermined deposition temperature by employing the inorganic material, lowering a temperature of at least the inorganic material layer to produce cracks in the inorganic material layer formed on the sacrifice layer, and removing the sacrifice layer and the inorganic material layer formed thereon. 
         [0013]    According to the present invention, cracks are produced by utilizing a difference between the thermal expansion coefficients of the sacrifice layer and the inorganic material layer formed thereon when the temperature of the substrate on which the sacrifice layer and the inorganic material layer have been formed is lowered. Thereby, the etchant becomes easier to penetrate to the sacrifice layer through the cracks, and the unwanted inorganic material layer is easily and cleanly removed. Thus, the structure containing the pattern of the inorganic material film can be manufactured. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIGS. 1A-1D  are diagrams for explanation of a method of forming a pattern of an inorganic material film according to the first embodiment of the present invention; 
           [0015]      FIG. 2  is a SEM image showing a PZT film fabricated by the method of forming a pattern of an inorganic material film according to the first embodiment of the present invention; 
           [0016]      FIGS. 3A-3F  are diagrams for explanation of a method of forming a pattern of an inorganic material film according to the second embodiment of the present invention; 
           [0017]      FIGS. 4A-4H  are diagrams for explanation of a method of manufacturing a piezoelectric device as application of the method of forming a pattern of an inorganic material film according to the first embodiment of the present invention; and 
           [0018]      FIG. 5  is a sectional view showing a diaphragm type piezoelectric actuator manufactured by applying the method of forming a pattern of an inorganic material film according to the first embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    Hereinafter, preferred embodiments of the present invention will be explained in detail by referring to the drawings. The same reference numerals are assigned to the same component elements and the description thereof will be omitted. 
         [0020]    In this application, a material forming a main part, that exerts a function of an element (a multilayered capacitor, a piezoelectric element, etc.), such as a dielectric film, a piezoelectric film, and so on is referred to as a material having functionality or simply as a functional material. Further, a film formed of a functional material is referred to as a functional film. 
         [0021]      FIGS. 1A-1D  are diagrams for explanation of a method of forming a pattern of an inorganic material film according to the first embodiment of the present invention. 
         [0022]    First, as shown in  FIG. 1A , a substrate  11  is prepared, and a pattern of a sacrifice layer  12  is formed thereon. For the substrate  11 , a material containing at least one of silicon (Si), copper (Cu), titanium (Ti), molybdenum (Mo), tungsten (W), gallium arsenide (GaAS), sapphire, and stainless steel (SUS) is used. Further, for the sacrifice layer  12 , a material having a different thermal expansion coefficient from that of an inorganic material layer  13 , which will be described later, is used. Conditions and specific materials of the sacrifice layer  12  will be specifically explained as below. The pattern of the sacrifice layer  12  is formed by the general liftoff method using a resist or the like. 
         [0023]    Then, as shown in  FIG. 1B , the inorganic material layer  13  is formed on the substrate  11  on which the sacrifice layer  12  has been formed. The inorganic material layer  13  is a layer to be a final target patterned film (an inorganic material film). For the inorganic material layer  13 , a material having a particular functionality like a piezoelectric material such as PZT (Pb (lead) zirconate titanate), a magnetic material such as Fe 2 O 3  and CrO 2 , a dielectric material such as BaTiO 3 , a superconducting material such as MgB 2 , or a general ceramic material (Al 2 O 3  and so on) is used. It is preferable that the inorganic material layer  13  has brittleness as a property at at least one temperature within a range between the temperature, at which the inorganic material layer  13  is formed, and the room temperature. Here, the brittleness generally refers to a property of being hard, brittle, and hardly deformable. Therefore, a material having brittleness leads to rupture with little plastic deformation. Further, in view of crystal structure, it is especially preferable that the inorganic material layer  13  has a columnar crystal structure. 
         [0024]    The inorganic material layer  13  can be formed by the known methods such as sputtering, chemical vapor deposition (CVD), and physical vapor deposition (PVD). In this regard, the deposition temperature is set to a high temperature of about 200° C. or more, desirably about 500° C. or more. Generally, the deposition temperature in CVD is 300° C. or more, and the deposition temperature for the piezoelectric film or the like by sputtering is 500° C. or more. 
         [0025]    Then, the substrate after deposition and the structures thereon (the sacrifice layer  12  and the inorganic material layer  13 ) are held under an environment at the room temperature. Thereby, with the temperature fall of the inorganic material layer  13 , cracks are produced in the inorganic material layer  13  formed on the sacrifice layer  12  due to the difference between thermal expansion coefficients of the sacrifice layer  12  and the inorganic material layer  13  as shown in  FIG. 1C . 
         [0026]    Further, the inorganic material layer  13  is immersed in an etchant. Thereby, the etchant penetrates to the sacrifice layer  12  through the cracks produced in the inorganic material layer  13 , and the sacrifice layer  12  and the inorganic material layer  13  thereon are removed (lifted off) together. Consequently, as shown in  FIG. 1D , the patterned functional film (the inorganic material layer  13 ) is obtained. 
         [0027]    As described above, in the first embodiment of the present invention, cracks are produced in the inorganic material layer  13 , and the etchant is penetrated through the cracks to the sacrifice layer  12  covered by the inorganic material layer  13 . Accordingly, even when the upper surface and the side surfaces of the sacrifice layer  12  are covered by the inorganic material layer  13 , for example, the sacrifice layer  12  can be easily peeled. 
         [0028]    Here, in some cases, the inorganic material layer  13  formed on the sacrifice layer  12  can not be separated from the inorganic material layer  13  even when the sacrifice layer  12  is removed by etching. In such a case, physical acting force (external force) may be exerted on the inorganic material layer  13  by twisting the substrate  11  or tapping the inorganic material layer  13 . Since the cracks have been already produced in the inorganic material layer  13  on the sacrifice layer  12 , the inorganic material layer  13  can be easily separated by the external force. 
         [0029]    For the sacrifice layer  12 , materials that satisfy the following conditions are used. The conditions are: (i) there is a large difference in thermal expansion coefficients between the material and the inorganic material layer  13 ; (ii) the material has high heat resistance; and (iii) there is an etchant with high selectivity for the material. 
         [0030]    The above condition (i) is required for selectively producing cracks in the inorganic material layer  13  on the sacrifice layer  12 . Specifically, a material having a high thermal expansion coefficient such that a ratio of the thermal expansion coefficient of the inorganic material layer  13  to the thermal expansion coefficient of the sacrifice layer  12  is, for example, 2:1 or more is desirably used. This is because the larger the difference between the thermal expansion coefficients of them, the more the cracks can be produced when the temperature of the substrate  11  on which the sacrifice layer  12  and the inorganic material layer  13  are formed is lowered from the deposition temperature to the room temperature. 
         [0031]    Further, the condition (ii) is required for forming the inorganic material layer  13  at a high temperature of 200° C. or more, desirably 500° C. or more. Furthermore, the condition (iii) is required for not to cause damage to the substrate  11  and the inorganic material layer  13  when the sacrifice layer  12  is removed. 
         [0032]    As familiar materials that satisfy these conditions, gold (Au) and germanium (Ge) are cited. For example, in the case where a pattern of piezoelectric film is formed, the thermal expansion coefficient of PZT is about 5×10 −6  (/K), and the thermal expansion coefficient (coefficient of linear expansion) of gold is about 14×10 −6  (/K). That is, the thermal expansion coefficient of gold is much larger, more than twice the thermal expansion coefficient of PZT. Therefore, while the temperature of the piezoelectric film deposited at a high temperature (e.g., 200° C. or more, desirably 500° C. or more) is lowered, many cracks can be produced in the piezoelectric film on the sacrifice layer. 
         [0033]    Further, since the melting point of gold is about 1064° C., gold can sufficiently withstand most high-temperature processes for forming the inorganic material layer  13 . Furthermore, for gold, there is an etchant that is inactive to most inorganic materials (functional materials, general ceramics, and so on) and substrate materials, or an etchant having high etching selectivity (e.g., an etching selection ratio is 50:1 or more). Specifically, an etchant prepared by dissolving 5 wt % iodine (I 2 ) and 10 wt % potassium iodide (KI) in 85 wt % water (H 2 O) is inactive to PZT and silicon. 
         [0034]    As example 1, a pattern of PZT film is formed using the method of forming a pattern of an inorganic material film according to the first embodiment of the present invention. 
         [0035]    As the substrate  11  shown in  FIGS. 1A-1D , a silicon (Si) wafer is used. First, a resist pattern is formed on the silicon wafer by using general photolithography, and a gold film having a thickness of 0.5 μm is formed thereon as the sacrifice layer  12  by vapor deposition. Then, a pattern of gold film is formed by lifting off the resist and the gold film thereon by using acetone. Furthermore, a PZT film having a thickness of 1.5 μm is formed as the inorganic material layer  13  by sputtering. The deposition temperature is 500° C. While the temperature of the silicon wafer, on which the gold film and the PZT film had been formed, is lowered to the room temperature, many cracks are produced in the PZT film on the gold film. Furthermore, the silicon wafer is immersed in the etchant prepared by dissolving 5 wt % iodine (I 2 ) and 10 wt % potassium iodide (KI) in 85 wt % water (H 2 O), and then, the gold film and the PZT film formed thereon are removed and a patterned PZT film is left on the silicon wafer. 
         [0036]      FIG. 2  is a photograph of the PZT film fabricated in example 1 taken with a SEM (scan electron microscope). In example 1, although the PZT film (having a thickness of about 1.5 μm) is much thicker than the gold film (having a thickness of about 0.5 μm) as the sacrifice layer, the unwanted PZT film could be cleanly lifted off as shown in  FIG. 2 . As found in the example, the PZT fabricated by sputtering has a columnar crystal structure and the PZT film pattern having a sharp section can be obtained utilizing the nature of the columnar crystal. 
         [0037]    As example 2, a pattern of a superconducting material, magnesium diboride (MgB 2 ) film is formed by using the method of forming a pattern of an inorganic material film according to the first embodiment of the present invention. 
         [0038]    As the substrate  11  shown in  FIGS. 1A to 1D , a sapphire substrate is used. First, a resist pattern is formed on the sapphire substrate by using general photolithography, and a germanium (Ge) film having a thickness of 100 nm is formed thereon as the sacrifice layer  12  by sputtering. Then, a pattern of Ge film is formed by lifting off the resist and the Ge film thereon by using acetone. Furthermore, an MgB 2  film having a thickness of 1 μm is formed as the inorganic material layer  13  by sputtering. The deposition temperature is 250° C. When the temperature of the sapphire substrate, on which the Ge film and the MgB 2  film have been formed, is lowered to the room temperature, many cracks are produced in the MgB 2  film on the Ge film. Furthermore, the sapphire substrate is immersed in a hydrogen peroxide solution as the etchant, and then, the Ge film and the MgB 2  film formed thereon are removed and a patterned MgB 2  film is left on the sapphire substrate. 
         [0039]    Next, a method of forming a pattern of an inorganic material film according to the second embodiment of the present invention will be explained. The method of forming a pattern of an inorganic material film according to the embodiment is more suitable for the case where the inorganic material film is made thicker than that in the first embodiment. The materials of the substrate, the sacrifice layer, the inorganic material (the functional material, the general ceramics, or the like) layer are the same as those in the first embodiment. 
         [0040]    First, as shown in  FIG. 3A , a resist pattern  22  is formed on a substrate  21  by photolithography. Then, an isotropic dry etching is performed on the substrate  21 , and then, the resist pattern  22  is removed with acetone or the like. Thereby, as shown in  FIG. 3B , a pattern with projections and depressions is formed on the substrate  21 . In the embodiment, an inorganic material film is formed on depressions  21   a  of the pattern with projections and depressions. When the pattern with projections and depressions is formed on the substrate, not only the above-mentioned method but also a known method such as wet etching with an alkaline solution may be used. 
         [0041]    Then, as shown in  FIG. 3C , a sacrifice layer  23  is formed on the projections formed on the substrate  21  by the general liftoff method by using a resist. 
         [0042]    Then, as shown in  FIG. 3D , an inorganic material layer  24  is formed on the substrate  21 , on which the sacrifice layer  23  has been formed, at a high deposition temperature. Subsequently, the inorganic material layer  24  is held under the room temperature environment to the lower temperature, and thereby, cracks are produced in the inorganic material layer  24  on the sacrifice layer  23  as shown in  FIG. 3E . 
         [0043]    Further, the inorganic material layer  24  is immersed in an etchant so that the etchant penetrates to the sacrifice layer  23  through the cracks. Consequently, the sacrifice layer  23  and the inorganic material layer  24  formed thereon are removed, and, as shown in  FIG. 3F , the patterned inorganic material film (the inorganic material layer  24 ) is obtained. 
         [0044]    As described above, according to the embodiment, since the level differences (the pattern with projections and depressions) are provided on the substrate and the areas in which the inorganic material film is to be formed are separated in advance, the sacrifice layer and the inorganic material film thereon can be reliably peeled even when the inorganic material film is thicker. 
         [0045]    As example  3 , a pattern of PZT film is formed by using the method of forming a pattern of an inorganic material film according to the second embodiment of the present invention. 
         [0046]    As the substrate  21  shown in  FIGS. 3A-3F , a silicon wafer is used. Further, the depressions  21   a  on the substrate are formed to have a depth of about 15 μm by using the Bosch process. Here, the Bosch process is an anisotropic dry etching process of etching the bottom while coating the sidewall and advantageous to form a pattern at a high aspect ratio. 
         [0047]    Furthermore, the sacrifice layer  23  is formed by forming a resist pattern on the substrate  21  by photolithography, forming a gold film having a thickness of 200 nm thereon by electron beam evaporation, and lifting off the resist and the gold film thereon by using acetone. Further, a PZT film having a thickness of 10 μm is formed as the inorganic material layer  24  by sputtering. The deposition temperature is 500° C. When the temperature of the silicon wafer, on which the gold film and the PZT film had been formed, is lowered to the room temperature, many cracks are produced in the PZT film formed on the gold film. Furthermore, the silicon wafer is immersed in the etchant prepared by dissolving 5 wt % iodine (I 2 ) and 10 wt % potassium iodide (KI) in 85 wt % water (H 2 O), and then, the gold film and the PZT film formed thereon are removed and a patterned PZT film is left on the silicon wafer. 
         [0048]    As explained above, according to the first and second embodiments, since the sacrifice layer having high heat resistance is used, the inorganic material layer can be deposited at a high temperature (200° C. or more, desirably 500° C. or more), which is not applicable to the conventional case of using a resist. Further, since the cracks are produced in the inorganic material layer and the etchant is penetrated through the cracks to the sacrifice layer, even when the thickness of the inorganic material layer is larger than that of the sacrifice layer, the sacrifice layer and the inorganic material layer thereon can be easily and cleanly removed. 
         [0049]    Especially, it is practical to use gold as the sacrifice layer because the gold itself is a general material and various technologies are widely known as deposition methods and patterning methods for gold. Further, the etchant for removing gold causes less damage to most inorganic materials (functional materials, general ceramics, and so on) and substrate materials, and therefore, the deterioration in quality including the function of the inorganic material film can be suppressed. 
         [0050]    Next, a method of manufacturing a piezoelectric device as application of the method of forming a pattern of an inorganic material film according to the first embodiment of the present invention will be explained. 
         [0051]      FIGS. 4A-4H  are diagrams for explanation of a method of manufacturing an FBAR (Film Bulk Acoustic Resonator) having an aluminum nitride (AlN) thin film. Here, the FBAR is a resonator having a structure in which a cavity is provided in the lower part of the resonator for freely vibrating a piezoelectric film. 
         [0052]    First, as shown in  FIG. 4A , an SOI (Silicon on Insulator) substrate  31  is prepared. Here, the SOI substrate is a substrate having a structure in which a silicon oxide (SiO 2 ) layer  31   b  is inserted between a support layer (silicon substrate)  31   a  and an active layer (surface silicon layer)  31   c.  In the embodiment, an SOI wafer having a diameter of 4 inches and containing a support layer  31   a  having a thickness of 0.4 mm, a silicon oxide layer  31   b,  and an active layer  31   c  having a thickness of 5 μm is used. A thermally oxidized film  32  having a thickness of 0.3 μm is formed on the active layer  31   c  by heat-treating the SOI substrate  31  in an electric furnace. 
         [0053]    Then, as shown in  FIG. 4B , an opening  31   d  is formed in the support layer  31   a  by anisotropic dry etching of the Bosch process or the like. 
         [0054]    Then, as shown in  FIG. 4C , a lower electrode layer  33  is formed in a region corresponding to the opening  31   d.  The lower electrode layer  33  may be formed of one kind of metal or may have a two-layer structure containing an adhesive layer provided for improving the junction with an adjacent layer and a conductive layer. In the embodiment, the lower electrode layer  33  contains a titanium (Ti) layer having a thickness of 10 nm as the adhesive layer and a platinum (Pt) layer having a thickness of 100 nm as the conductive layer. Further, the pattern of the lower electrode layer  33  is formed by reactive ion etching (RIE), for example. 
         [0055]    Then, as shown in  FIG. 4D , a gold film having a thickness of 200 nm is formed by electron beam evaporation and a pattern is formed by the general liftoff method thereon, and thereby, a sacrifice layer  34  of gold film is formed in the region except the position corresponding to the opening  31   d.    
         [0056]    Then, as shown in  FIG. 4E , an aluminum nitride (AlN) layer  35  is formed on the substrate  31 , on which the sacrifice layer  34  has been formed, by magnetron sputtering at a deposition temperature of 250° C. The temperature of the SOI substrate  31 , on which the sacrifice layer  34  of gold film and the aluminum nitride layer  35  have been formed, is lowered to the room temperature, and thereby, cracks are produced in the aluminum nitride layer  35  on the sacrifice layer  34  as shown in  FIG. 4F . 
         [0057]    Then, the aluminum nitride layer  35  is immersed in an etchant prepared by dissolving 5 wt % iodine (I 2 ) and 10 wt % potassium iodide (KI) in 85 wt % water (H 2 O), and thereby, the sacrifice layer  34  and the aluminum nitride layer  35  thereon are removed. Thus, a patterned aluminum nitride layer  35  is obtained as shown in  FIG. 4G . 
         [0058]    Furthermore, as shown in  FIG. 4H , an upper electrode layer  36  is formed by forming a titanium layer having a thickness of 10 nm and a platinum layer having a thickness of 100 nm on the aluminum nitride layer  35  and forming a pattern in those layers by dry etching. Thereby, the FBAR having the AlN thin film is completed. 
         [0059]    Next, a method of manufacturing another piezoelectric device as application of the method of forming a pattern of an inorganic material film according to the first embodiment of the present invention will be explained. 
         [0060]      FIG. 5  is a sectional view showing a diaphragm type piezoelectric actuator. Here, the diaphragm type piezoelectric actuator is an actuator for displacing diaphragms  41   b  to  43  by applying a voltage between a lower electrode layer  42  and an upper electrode layer  45  to expand and contract a piezoelectric film  44 . Such an actuator is applied to micropumps, ultrasonic transducers, inkjet heads, and so on. 
         [0061]    The diaphragm type piezoelectric actuator is fabricated in the following manner. First, an SOI substrate  41  is prepared. In the embodiment, an SOI wafer having a diameter of 4 inches and containing a support layer  41   a  having a thickness of 0.4 mm, a silicon oxide layer  41   b,  and an active layer  41   c  having a thickness of 10 μm is used. A thermally oxidized film  42  having a thickness of 0.5 μm is formed on the active layer  41   c  by heat-treating the SOI substrate  41  in an electric furnace. 
         [0062]    Then, a lower electrode layer  43  containing a titanium (Ti) layer having a thickness of 20 nm and a platinum (Pt) layer having a thickness of 150 nm is formed on the thermally oxidized film  42 . 
         [0063]    Furthermore, a pattern of the piezoelectric film  44  having a thickness of 3 μm is formed in a position corresponding to an opening  41   d  by the method of forming a pattern of an inorganic material film according to the first embodiment. That is, a gold film having a thickness of 200 nm as a sacrifice layer is formed in the region except the position corresponding to the opening  41   d  on the lower electrode  43 . Then, PZT is deposited thereon by sputtering and the temperature of the PZT film is lowered, and thereby, cracks are produced in the PZT film on the gold film. Furthermore, the gold film and the PZT film thereon are removed by using an etchant for gold (5 wt % iodine, 10 wt % potassium iodide, and 85 wt % water). 
         [0064]    The upper electrode layer  45  is formed on thus formed pattern of the piezoelectric film  44 . That is, a resist pattern for the upper electrode layer  45  is formed by photolithography, a titanium layer having a thickness of 20 nm and a platinum layer having a thickness of 150 nm are formed by sputtering, and further, the resist pattern is removed with acetone. Thereby, the diaphragm type piezoelectric actuator is completed. 
         [0065]    In the above-explained examples 1-3 and various methods of manufacturing devices, a pattern of an inorganic material film having functionality is formed. However, a pattern of a film can be formed by using the same method with respect to inorganic materials having no specific function (so-called ceramics such as metal oxides including Al 2 O 3  and MgO and metal nitrides). For example, accurate channels (e.g., ink supply channels in an inkjet head), micro vibrators (e.g., vibratable walls as part of an ink chamber of an inkjet head), and so on can be formed with general ceramic materials by applying the first and second embodiments.