Patent Publication Number: US-6910272-B2

Title: Method of manufacturing an ink jet recording head

Description:
This application is a Divisional of U.S. application Ser. No. 10/073,367, filed Feb. 13, 2002 now is U.S. Pat. No. 6,692,114. The above noted prior application is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to an ink jet recording head in which a part of each pressure generating chamber communicating with nozzle orifices for ejecting ink droplets is formed with a vibration plate, a piezoelectric element is provided on the vibration plate interposed, and an ink droplet is ejected by a displacement of the piezoelectric element and a method of manufacturing the recording head, and an ink jet recording apparatus. 
   The ink jet recording head in which a part of each pressure generating chamber communicating with nozzle orifices for ejecting ink droplets is formed with a vibration plate, and the vibration plate by the piezoelectric element is deformed to pressurize ink in the pressure generating chamber to eject an ink droplet through the nozzle orifice, is known. This type of recording head is categorized into two types of recording heads; one uses the piezoelectric actuators of the longitudinal vibration mode in which the piezoelectric element axially expands and shrinks, and the other uses the piezoelectric actuators of the flexural vibration mode. Those types of recording heads have been put into practice. 
   The former recording head is advantageous in that the recording head suitable for the high density printing may be manufactured since the volume of the pressure generating chamber is varied by bringing the end face of the piezoelectric element into contact with the vibration plate. However, it has a difficult step of cutting the piezoelectric elements in a comb shape in alignment with the pitches of the nozzle orifice array, and needs another step of positioning and fixing the cut piezoelectric elements to the pressure generating chambers. In this respect, the manufacturing process is complex. 
   The latter recording head is advantageous in that the piezoelectric elements may be formed on the vibration plates in a relatively simple manner that a green sheet of piezoelectric material is bonded onto the vibration plates in conformity with a shape of the pressure generating chambers, and then baked. However, this recording head is disadvantageous in that since the flexural vibration is utilized, an area of some extent must be secured for each the piezoelectric element. Accordingly, it is difficult to array the piezoelectric elements at high density. 
   To solve the disadvantage of the latter recording head, there is proposed a technique in which a piezoelectric layer is uniformly formed over the entire surface of the vibration plate, and the piezoelectric layer is cut by a lithography process to form individual piezoelectric elements for each pressure generating chamber in accordance with arrangements of the pressure generating chambers (see JP-A-5-286131). 
   This technique enables to eliminate the work of bonding the piezoelectric elements to the vibration plates. Accordingly, the piezoelectric elements may be manufactured by a precise and simple process, using the lithography process. Additionally, the piezoelectric element is thinned and hence driven at high speed. 
   In such an ink jet recording head, the pressure generating chambers are formed penetrating the passage forming substrate in a manner that the passage forming substrate is selectively etched by anisotropic etching process from a surface of the passage forming substrate opposite to the piezoelectric-elements to the vibration plate. 
   When the anisotropic etching process is carried out in the form of a wet etching process using an alkaline aqueous solution, the alkaline aqueous solution or etching reaction products penetrate through the vibration plate to damage the piezoelectric elements, at the end of the etching process. 
   In the dry etching process, the etching is terminated indefinitely, therefore it is difficult to control the width of the vibration plate side of the pressure generating chamber. Accordingly, the pressure generating chambers cannot be formed with high accuracy by the dry etching process. 
   Further, in such an ink jet recording head, the pressure generating chambers are formed by the etching after the piezoelectric elements are formed. Accordingly, a position of the vibration plate side of the pressure generating chamber is instable by the dispersion in verticality of the pressure generating chambers. An accuracy of a relative position shift of the piezoelectric element to the pressure generating chambers is low, so that the ink ejecting characteristic and stability are low. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide an ink jet recording head having highly reliable piezoelectric elements and the improved ink ejecting characteristic and stability and a method of manufacturing the same, and an ink jet recording apparatus. 
   In one broad aspect of the invention, there is provided a first ink jet recording head having a passage forming substrate made of a silicon monocrystalline substrate including at least one pressure generating chamber communicating with a nozzle orifice; a vibration plate provided on a surface of the passage forming substrate; a piezoelectric element provided on the vibration plate having a lower electrode film, a piezoelectric layer and an upper electrode; a wide portion provided in the pressure generating chamber on a side of the vibration plate, extending in a longitudinal direction of the pressure generating chamber, a groove formed on a side of the wide portion, extending in a longitudinal direction of the wide portion; and an etching stop layer provided in the groove, defining a side wall of the wide portion as viewed in the width direction thereof to restrict the spread of the etching in the width direction. 
   In the first ink jet recording head, the width of the wide portion of the pressure generating chamber is restricted easily and reliably by the etching stop layer. As a result, the pressure generating chamber is manufactured highly accurately. 
   In a second ink jet recording head, the etching stop layer has each an insulating property. 
   In the second ink jet recording head, since the etching stop layer has an insulating property, no current leaks to the ink in the pressure generating chamber. 
   In a third ink jet recording head, the etching stop layer is made of the same material as that of a part of the vibration plate. 
   In the third ink jet recording head, the etching stop layer is made of the same material as that of a part of the vibration plate. Accordingly, the manufacturing process is simplified. 
   In a fourth ink jet recording head, the etching stop layer is made of silicon oxide. 
   In the fourth ink jet recording head, the etching stop layer is formed easily and reliably. 
   In a fifth ink jet recording head, the width of each groove is selected to be smaller in value than a value which is two times as large as the thickness of the etching stop layer. 
   In the fifth ink jet recording head, the etching stop layer is reliably formed within the groove. 
   In a sixth ink jet recording head, at least the vibration plate side of the pressure generating chambers are formed by anisotropic dry etching process. 
   In the sixth ink jet recording head, the piezoelectric element is reliably prevented from being damaged by an etching solution or etching reaction product, and the pressure generating chamber is manufactured highly accurately. 
   In another broad aspect, there is provided an ink jet recording apparatus being provided with the first to sixth ink jet recording head as described above. 
   The thus constructed ink jet recording apparatus is improved in the ink ejecting characteristics. 
   In yet another broad aspect, there is provided a method of manufacturing an ink jet recording head having a passage forming substrate consisting of a silicon monocrystalline substrate in which pressure generating chambers communicating with nozzle orifices are formed, and piezoelectric elements being formed on one of surfaces of the passage forming substrate with vibration plates interposed therebetween, each piezoelectric element including a lower electrode film, a piezoelectric layer and an upper electrode, which are formed with thin films formed by film forming and lithography processes. The method preferably comprises the steps of: forming grooves on both sides of each region at which the pressure generating chamber is to be formed in one of surfaces of the passage forming substrate, the grooves extending in the longitudinal direction; forming, in the grooves, etching stop layers which restrict the etching of the passage forming substrate; forming the piezoelectric elements by successively laminating the lower electrodes, the piezoelectric layers and the upper electrodes on one of the surfaces of the passage forming substrate with vibration plates being interposed therebetween, and by patterning the resultant structure; and forming the pressure generating chamber by etching out at least the vibration plate side of the passage forming substrate by the anisotropic dry etching process till the etching stop layers are exposed. 
   In the method of manufacturing the ink jet recording head, the spread of the etching in the width direction of the vibration plate side of the pressure generating chamber is easily controlled, so that the pressure generating chambers are manufactured highly accurately. 
   In another ink jet recording head manufacturing method, in the pressure generating chamber forming step, the passage forming substrate is subjected to anisotropic wet etching, and then anisotropic dry etching, thereby forming the pressure generating chambers. 
   In this method of manufacturing the ink jet recording head, the pressure generating chambers are formed by anisotropic wet etching and anisotropic dry etching. Accordingly, the time taken for etching may be reduced, and its manufacturing cost is reduced. 
   In yet another ink jet recording head manufacturing method, the etching stop layers have each an insulating property. 
   In the method of manufacturing the ink jet recording head, since the etching stop layers have each an insulating property, no current leaks to the ink in the pressure generating chambers. 
   In yet another ink jet recording head manufacturing method, the etching stop layers are made of the same material as that of a part of the vibration plate. 
   In the method of manufacturing the ink jet recording head, the etching stop layers are made of the same material as that of a part of the vibration plate. Accordingly, the manufacturing process is simplified. 
   In another ink jet recording head manufacturing method, the etching stop layers are made of silicon oxide. 
   In the method of manufacturing the ink jet recording head, the etching stop layers are formed easily and reliably. 
   In a further ink jet recording head manufacturing method, in the step of forming the grooves, the width of each groove is selected to be smaller in value than a value which is two times as large as the thickness of the etching stop layer. 
   In the method of manufacturing the ink jet recording head, the etching stop layers are reliably formed within the grooves. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing an ink jet recording head according to an embodiment 1 of the present invention; 
       FIGS. 2A and 2B  are cross sectional views showing the ink jet recording head according to the embodiment 1 of the invention;  FIG. 1A  is a cross sectional view showing a pressure generating chamber, the illustration being viewed in the longitudinal direction, and  FIG. 2B  is a cross sectional view showing taken on line A-A′ in  FIG. 2A ; 
       FIGS. 3A-3D  are cross sectional views showing a method of manufacturing the ink jet recording head according to the embodiment 1 of the invention, the illustration being as viewed in a direction in which pressure generating chambers are arranged side by side; 
       FIGS. 4A-4C  are cross sectional views showing a method of manufacturing the ink jet recording head according to the embodiment 1 of the invention, the illustration being as viewed in a direction in which pressure generating chambers are arranged side by side; 
       FIGS. 5A-5C  are cross sectional views showing a method of manufacturing the ink jet recording head according to the embodiment 1 of the invention, the illustration being as viewed in a direction in which pressure generating chambers are arranged side by side; and 
       FIG. 6  is a perspective view showing the ink jet recording head according to the embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The preferred embodiments of the present invention will be described with reference to the accompanying drawings. 
   (Embodiment 1) 
     FIG. 1  is an exploded view showing an ink jet recording head according to an embodiment 1 of the present invention.  FIG. 2A  is a cross sectional view showing a pressure generating chamber, the illustration being viewed in a direction in which the pressure generating chambers are arranged side by side in the ink jet recording head.  FIG. 2B  is a cross sectional view showing taken on line A-A′ in FIG.  2 A. 
   As shown, a passage forming substrate  10  consists of a silicon monocrystalline substrate having a face ( 110 ) in the embodiment. One of the surfaces of the passage forming substrate  10  is an opened surface, and an elastic film  50  forming one of the surfaces of the pressure generating chamber  12  is formed on the other surface. 
   In the embodiment, the elastic film  50  is formed with a first elastic film  51  which is made of silicon dioxide (SiO 2 ) and formed on the passage forming substrate  10 , and a second elastic film  52  which is zirconium dioxide (ZrO 2 ) and formed on the first elastic film  51 . It is not essential that the elastic film  50  is made up of a plurality of layers. 
   Pressure generating chambers  12 , which are formed by an anisotropic etching process and partitioned by a plurality of partitioning walls  11 , are arranged side by side in the widthwise direction. A wide portion  15  is formed, by an anisotropic dry etching process, on the elastic film  50  side of each pressure generating chamber  12 . The wide portions, each extending in the widthwise direction of the pressure generating chamber  12 , and are arranged in the longitudinal direction of the pressure generating chamber  12 . 
   Grooves  16 , while extending in the longitudinal direction of the pressure generating chamber  12 , are each formed on both sides of each wide portion  15 . An etching stop layer  110  is put in the groove  16 . The side faces of each wide portion  15  are defined by the etching stop layers  110 . 
   The pressure generating chambers  12  having the wide portions  15  are formed in the following manner. Part of the pressure generating chambers are formed by applying anisotropic wet etching to the passage forming substrate  10  from one of the surfaces of the passage forming substrate to a region thereof near the elastic film  50 . Thereafter, anisotropic dry etching is applied thereto till the etching stop layers  110  are exposed. 
   The etching stop layers  110  are provided for restricting the spread of the etching in the width direction of the wide portions  15  of the pressure generating chambers  12  when the pressure generating chambers  12  are formed in the passage forming substrate  10  by anisotropic dry etching. The etching substantially stops when the etching of the passage forming substrate  10  progresses till the etching stop layer  110  is exposed. A material of the etching stop layer  110  may be any material if it has an insulating property and is not etched by the anisotropic dry etching. For example, in the embodiment, a part of the first elastic film  51  is used as the etching stop layer  110  in a manner that the first elastic film  51  made of silicon dioxide, provided on the passage forming substrate  10 , is filled into the grooves  16 . 
   Thus, the etching stop layer  110  is provided on the passage forming substrate  10 , thereby restricting the width of each wide portions  15  of the pressure generating chambers  12 . With this feature, even if a position of the elastic film  50  side of the pressure generating chamber  12  is made instable by the dispersion in verticality of the pressure generating chambers  12 , a tolerance of a relative position shift of the piezoelectric element may be made large. 
   A protecting film  55  formed with a silicon dioxide layer is formed on the surface of the opened surface of the passage forming substrate  10 , by thermally oxidizing the surface of the passage forming substrate  10 . A nozzle plate  20  with nozzle orifices  21  formed therein is bonded onto the protecting film  55  with adhesive, a thermal deposition film or the like being interposed therebetween. The nozzle plate  20  has a thickness of 0.1 to 1 mm, and is made of glass, monocrystalline silicon, stainless steel (SUS) or the like, whose expansion coefficient is 2.5 to 4.5[×10 −6 /° C.] at 3000° C. The nozzle plate  20  entirely covers one of the surfaces of the passage forming substrate  10 , and also serves as a reinforcing plate for protecting the passage forming substrate  10  consisting of a silicon monocrystalline substrate against impact and external force applied thereto. 
   Additionally, the pressure generating chambers  12  is connected to a common ink chamber  31  via ink supply ports  22 , which are formed at positions corresponding to the first ends of the pressure generating chambers  12  of the nozzle plate  20 . Ink is supplied from the common ink chamber  31  to the pressure generating chambers  12 , through the ink supply ports  22 . 
   An ink introducing port  23  through which ink is supplied from exterior to the common ink chamber  31  is formed in a part protruded from an end of the passage forming substrate  10  of the nozzle plate  20 . 
   An ink-chamber forming plate  30  and an ink chamber side plate  40 , which cooperatively form the common ink chamber  31 , are joined to a part of the nozzle plate  20  which contains the ink supply ports  22  and the ink introducing port  23 . 
   The ink-chamber forming plate  30  forms the periphery wall of the common ink chamber  31 , and is formed by punching a stainless plate having a thickness, which is appropriately determined depending on the number of nozzle orifices and the ink ejection frequency. In the embodiment, a thickness of the ink-chamber forming plate  30  is 0.2 mm. 
   The ink chamber side plate  40  is formed with a stainless plate, and one of its surfaces forms one side wall of the common ink chamber  31 . The ink chamber side plate  40  is half-etched to form a recess  40   a  in a part of the other surface, whereby a thin wall  41  is formed. The thin wall  41  is provided for absorbing a pressure, which is generated at the time of ejecting the ink droplet and acts toward the side opposite to the nozzle orifices  21 . And it prevents an unnecessary positive or negative pressure from acting on the other pressure generating chamber  12  by way of the common ink chamber  31 . 
   The size of the pressure generating chamber  12  for applying the pressure to the ink for ejection and the size of the nozzle orifices  21  for ejecting ink droplets are optimized in accordance with the amount of ink droplet ejected, ejecting speed, and ejection frequency. In the recording of 360 ink droplets per inch, it is necessary to accurately form the nozzle orifices  21  each having a diameter of several tens μm. 
   A lower electrode film  60  of about 0.2 μm thick, a piezoelectric layer  70  of about 1 μm thick , and an upper electrode  80  of about 0.1 μm are laminated on the elastic film  50  of the passage forming substrate  10  by a process to be described later, whereby a piezoelectric element  300  is formed. Here, the piezoelectric element  300  indicates a portion including the lower electrode film  60 , piezoelectric layer  70  and upper electrode  80 . Generally, the piezoelectric element  300  is formed such that either of the electrodes is used as a common electrode, and the other electrode and the piezoelectric layer  70  are patterned every pressure generating chamber  12 . In the specification, a portion which includes the electrode and piezoelectric layer  70  as patterned, and will be piezoelectrically distorted when voltage is applied to between both the electrodes, will be referred to as a piezoelectric-material active part. In the present embodiment, the lower electrode film  60  is used as a common electrode of the piezoelectric element  300 , the upper electrodes  80  are individual electrodes of the piezoelectric element  300 . However, the former may be used as the individual electrodes and the latter may be used as the common electrode at the convenience of designing the drive circuit and wiring require. If so done, no problem arises. In either case, the piezoelectric-material active part is formed every pressure generating chamber. In the specification, a combination of the piezoelectric element  300  and the vibration plate in which a displacement is caused wen the piezoelectric element  300  is driven, will referred to as a piezoelectric actuator. In the embodiment mentioned above, the elastic film  50  and the lower electrode film  60  serve as the vibration plate, and the lower electrode film may additionally have a function of the elastic film. 
   The upper electrodes  80  as the individual electrodes of the piezoelectric element  300  are connected to an external wiring through lead electrodes  90 , which extend on the elastic film  50  from one end of the piezoelectric element  300  as viewed in the longitudinal direction. 
   The thus constructed ink jet recording head of the embodiment operates in the following way. Ink is introduced into the head through the ink introducing port  23  connecting to an external ink supplying device (not shown). After the ink flow structure ranging from the common ink chamber  31  to the nozzle orifices  21  is filled with the ink. Voltage is applied to between the lower electrode film  60  and the upper electrode  80  of each pressure generating chamber  12  in accordance with a recording signal derived from an external drive circuit (not shown). The elastic film  50 , lower electrode film  60  and piezoelectric layer  70  are flexurally deformed. As a result, a pressure within each pressure generating chamber  12  increases, then an ink droplet is ejected from the nozzle orifice  21  associated therewith. 
   A method of manufacturing an ink jet recording head thus constructed will be described in detail.  FIGS. 3  to  5  show, in cross sectional views in a direction in which pressure generating chambers are arranged side by side, the method of manufacturing the ink jet recording head. 
   As shown in  FIG. 3A , a wafer of a silicon monocrystalline substrate, which will be a passage forming substrate  10 , is thermally oxidized in a diffusion being set at about 1100° C. A mask  51 A made of silicon oxide is formed on one of the surfaces of the passage forming substrate  10 , and is patterned to form openings  16   a  therein. At the same time, a protecting film  55  made of silicon dioxide is formed on the other surface of the passage forming substrate. 
   Subsequently, as shown in  FIG. 3B , grooves  16  are formed in the passage forming substrate  10  by anisotropic etching, by using the mask  51 A having he openings  16   a  formed therein as a mask pattern. 
   In this case, the anisotropic etching may be anisotropic wet etching or anisotropic dry etching, and the etching is not limited to the anisotropic etching. 
   As shown in  FIG. 3C , the passage forming substrate  10  is thermally oxidized again, and another first elastic film  51  made of silicon oxide is formed on the one surface of the passage forming substrate  10 . At this time, the first elastic film  51  is formed entirely covering the inner surfaces of the grooves  16 , so that etching stop layers  110  made of silicon oxide are formed in the grooves  16 . 
   The first elastic film  51  is formed on the surface of the passage forming substrate  10 , while being substantially uniform in thickness. To fill the first elastic film  51  in the grooves  16 , it is preferable that the width of each groove  16  is selected to be smaller in value than a value which is two times as large as the thickness of the first elastic film  51 . By so selected, the first elastic film  51  reliably fills the grooves  16 . 
   In the embodiment, the first elastic film  51  and the protecting film  55  are formed by thermally oxidizing the passage forming substrate. Instead, it may be formed at a relatively low temperature, 350° C.˜500° C., by a TEOS-CVD method. In the embodiment, the etching stop layers  110  are formed in the grooves  16  in a manner that the first elastic film  51  is formed covering the inner surfaces of the grooves  16 . In an alternative, the etching stop layers are formed in the grooves  16  by a material other than the first elastic film  51 , and then the first elastic film  51  is formed on the surface of the passage forming substrate  10  and the etching stop layers. The etching stop layers whose material is the same as that of the first elastic film  51  may be formed in a process step, which is different from the step of forming the first elastic film  51 , as a matter of course. 
   Next, as shown in  FIG. 3D , a second elastic film  52  is formed over the first elastic film  51 . In the present embodiment, a zirconium layer is formed on the first elastic film  51 , and is thermally oxidized in a diffusion being set at 500˜1200° C., thereby forming a second elastic film  52  of zirconium dioxide. And the first elastic film  51  and the second elastic film  52  cooperate to form an elastic film  50 . 
   In the embodiment, the first elastic film  51  fills the grooves  16  such that it reaches the surface of the passage forming substrate  10  by using part of the first elastic film  51  for the etching stop layers  110 . Accordingly, the surface of the second elastic film  52  is substantially flat. 
   Subsequently, as shown in  FIG. 4A , a lower electrode film  60  is entirely formed on the elastic film  50  side of the passage forming substrate  10  by sputtering and is patterned into a predetermined shape. Platinum, iridium or the like is preferable as a material of the lower electrode film  60 . The reason for this is that a piezoelectric layer  70 , which will be described later and formed by a sputtering method or sol-gel method must be baked and crystallized at about 600 to 1000° C. in an air or oxygen atmosphere after the film formation. A material of the lower electrode film  60  must maintain its conductivity at such a high temperature and oxidizing atmosphere. In particular, in a case where lead zirconium titanate (PZT) is used for the piezoelectric layer  70 , it is preferable that the conductivity of the lower electrode film material is less varied by diffusion of the lead oxide. For those reasons, platinum or iridium is preferable for the lower electrode film material. 
   Subsequently, as shown in  FIG. 4B , a piezoelectric layer  70  and an upper electrode film  80  are formed, and a piezoelectric element  300  is patterned by etching only of the piezoelectric layer  70  and the upper electrode film  80 . 
   In the embodiment, the piezoelectric layer  70  is formed by called sol-gel process, viz., in a manner that a sol which is formed by dissolving and dispersing metal organic into a catalyst is coated and dried into a gel, and the gel is baked at high temperature, whereby a piezoelectric layer  70  made of metal oxide is formed. PZT-based materials are preferable for the material of the piezoelectric layer  70  which it is used for an ink jet recording head. A film formation method is not limited for forming the piezoelectric layer  70 . Spin coating process such as sputtering method or metal organic deposition process (MOD) may be employed. 
   The following method may be employed. In the method, a percursor film of lead zirconium titanate is formed by a sol-gel process, sputtering or MOD process, and then is crystallized at low temperature by high pressure process in an alkaline solution. 
   High electrical conductivity materials such as aluminum, gold, nickel, platinum, or other metals and a conductive oxide may be used as a material of the upper electrode film  80 . In the embodiment, platinum is used for film formation by sputtering. 
   Next, lead electrodes  90  are formed entirely on the passage forming substrate  10  and patterned every piezoelectric element  300 , as shown in FIG.  4 C. 
   The film formation process is as mentioned above. Following the film formation, pressure generating chambers  12  are formed by anisotropic etching process. 
   As shown in  FIG. 5A , openings  55   a  are formed in a region of a protecting film  55  which is formed on the side of the passage forming substrate  10  opposite to the side thereof by patterning the region of the protecting film in which pressure generating chambers  12  are to be formed. 
   Subsequently, as shown in  FIG. 5B , recesses  12   a  which will be parts of the pressure generating chambers  12  are formed by anisotropic wet etching process by use of the protecting film  55  having openings  55   a  as a mask pattern. 
   Where the anisotropic wet etching is used, recesses  12   a  may be formed to have a predetermined depth without forming through holes in the passage forming substrate  10  by etching, if the half etching is used. Accordingly, there is no case that an alkaline aqueous solution used in the anisotropic wet etching or etching reaction products penetrate through the elastic film  50  to damage the piezoelectric elements  30 . 
   Then, as shown in  FIG. 5C , the recesses  12   a  as formed by anisotropic wet etching are continuously subjected to anisotropic dry etching process, to thereby form pressure generating chambers  12 . 
   In the anisotropic dry etching process, the etching is continued till the etching reaches the first elastic film  51 . In the anisotropic dry etching process, the etching indefinitely ends, so that the pressure generating chambers  12  spread in width along the first elastic film  51  to form wide portions  15 . At the time, the etching substantially stops in the width direction at a time point where the etching stop layers  110  formed in the grooves  16  are exposed. As a result, the wide portions  15  are formed on the elastic film  50  side of each pressure generating chamber  12  in a state that it extends in the widthwise direction of the pressure generating chamber  12  and has predetermined width. 
   It is satisfactory that the depth of each groove  16  is selected to be such a depth value, i.e., about 0.5 μm or larger, as to prevent that when the pressure generating chambers are formed by the anisotropic dry etching process, the wide portions  15  formed on the elastic film  50  side exceed each beyond the etching stop layer  110  formed in the groove  16  and spread. 
   With this feature, even if a position of the vibration plate side of the pressure generating chamber  12  is made instable by the dispersion in verticality of the pressure generating chambers, a tolerance of a relative position shift between the piezoelectric element  300  and the pressure generating chambers  12  may be made large by providing the etching stop layers  110  to restrict the width of the wide portions  15  of the pressure generating chambers  12 . 
   Thus, in the embodiment, the first elastic film  51  fills the grooves  16  such that it reaches the surface of the passage forming substrate  10  by using the etching stop layer  110  made of the same material as of the first elastic film  51 , i.e., a part of the first elastic film  51 , and the surface of the second elastic film  52  is substantially flat. With this feature, there is eliminated the stress concentration by deformation of the piezoelectric element  300 , and hence the elastic film  50  is prevented from being broken. 
   The elastic film  50  side of the pressure generating chamber  12  is formed by the anisotropic dry etching process, and the opening side of the pressure generating chambers is formed by the anisotropic wet etching process. Accordingly, the piezoelectric element  300  is reliably prevented from being damaged. It is satisfactory that at least the elastic film  50  side of the pressure generating chambers  12  are formed by the anisotropic dry etching process. Accordingly, the pressure generating chambers  12  may be formed by the anisotropic dry etching process. 
   In this way, a number of chips are simultaneously formed on a single wafer by the sequential film forming steps and the anisotropic etching processes, and after the process ends, the wafer is divided into passage forming substrates  10  each of one chip size as shown in FIG.  1 . Then, a nozzle plate  20 , an ink-chamber forming plate  30  and an ink chamber side plate  40  are successively bonded to each of those passage forming substrates  10 , whereby a unit body or an ink jet recording head is formed. 
   Another Embodiment 
   While the ink jet recording head and the method of manufacturing the same, which are believed to be the preferred embodiments of the invention, have been described, it should be understood that the invention is not limited to such. 
   The ink jet recording head of the embodiment 1 forms a part of a recording head unit provided with ink passages communicating with the ink cartridges or the like, and is mounted on an ink jet recording apparatus.  FIG. 6  shows an example of the ink jet recording head. 
   As shown in  FIG. 6 , ink cartridges  2 A and  2 B, which form an ink supplying device, are detachably mounted on recording head units  1 A and  1 B provided with recording heads, respectively. A carriage  3  on which the recording head units  1 A and  1 B are mounted is axially movable along a carriage shaft  5  mounted on an apparatus body  4 . The recording head units  1 A and  1 B eject a black ink composition and color ink compositions, respectively. 
   A driving force by a drive motor  6  is transmitted to the carriage  3  by a way of a plurality of gears (not shown) and a timing belt  7 , so that the carriage  3  having the recording head units  1 A and  1 B mounted thereon is moved along the carriage shaft  5 . The head body  4  includes a platen  8  extending along the carriage  3 . The platen  8  is driven to rotate by a driving force of a paper feed motor (not shown). In this case, a recording sheet S as a recording medium of paper, which is fed by the feeding roller or the like, is wound on the platen  8 , and transported. 
   As seen from the foregoing description, wide portions are provided on the vibration plate side of the pressure generating chambers, and the etching stop layers for restricting the spread of the etching in the width direction of the wide portions, are formed in the passage forming substrate. With such a technical feature, the width of the wide portions of the vibration plate side of the pressure generating chambers are restricted by the etching stop layers. As a result, the pressure generating chambers are manufactured highly accurately, and the ink ejecting characteristic and stability are improved. In such a method of manufacturing pressure generating chambers, at least the vibration plate side of the pressure generating chambers are formed by the anisotropic dry etching process. Accordingly, the piezoelectric elements are not damaged, and hence piezoelectric elements improved in reliability may be manufactured.