JP2006225745A - Structure of thin film element and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the reliability of a process when a film deposited on a polysilicon or silicon nitride film is subjected to etching by CDE (Chemical Dry Etching), and to improve the reliability in the CDE process of a Ta cavitation resistant film on a protective film of BJ. <P>SOLUTION: Thin SiON or SiOx is deposited on the upper side of a polysilicon or silicon nitride film by plasma CVD (Chemical Vapor Deposition), so as to provide an etching stop layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a configuration of a thin film functional element on which a film containing silicon or silicon nitride as a main component, for example, various sensors, a thermal head, an ink jet recording head, a semiconductor element, and the like, and a manufacturing method thereof.

  When a thin film of another material is deposited on a film containing silicon or silicon nitride as a main component and is to be etched in the gas phase, generally reactive ion etching (RIE) or chemical dry etching is used. Etching was used to control the etching time by controlling the etching time.

Japanese Patent Application Laid-Open No. 5-129318 discloses an example in which an oxide film is deposited on polysilicon as an etching stop layer during wet etching of a nitride film in a bipolar transistor manufacturing process. Japanese Patent Laid-Open No. 9-134956 discloses an example in which a silicon nitride film is deposited as an etching stop layer on a silicon oxide film during dry etching of an antireflection film on a contact hole in a semiconductor substrate manufacturing process. Is disclosed.
Japanese Patent Laid-Open No. 5-129318 JP-A-9-13495

  In conventional RIE or CDE, if the etching film thickness is controlled by controlling the reaction time, the underlying film of silicon or silicon nitride as a main component may be removed due to overetching, or silicon or silicon nitride is mainly used. There was also a problem that the surface of the film as a component was roughened. Further, when the etching stop layer is thickened, the device characteristics may be changed due to the influence of the physical properties of the underlying film.

  In an ink jet recording head that heats ink with a heater, SiN is used as a protective film in order to protect the heater from alkaline ink. However, when the CDE of Ta of the anti-cavitation film thereon is damaged, SiN is damaged. There was sometimes. However, when SiON or the like is used instead of SiN, the ink resistance may be lowered. In addition, if a thick etching stop film is formed on SiN, the heat of the heater becomes difficult to be transmitted to the ink, which may reduce the response frequency.

  The above-mentioned problem is a thin film functional element in which a film mainly composed of silicon nitride is laminated in a constituent material according to the present invention, and a silicon nitride oxide thinner than the silicon nitride film on the surface of the silicon nitride film This is solved by a thin film functional element characterized in that a film or a silicon oxide film is laminated.

  In addition, as a heater protective film for an ink jet recording head, a film mainly composed of silicon nitride is deposited, and a silicon nitride oxide film or silicon oxide film thinner than the silicon nitride film is laminated on the surface, and cavitation resistance is further formed thereon. This is solved by an ink jet recording head characterized in that a film of Ta or an alloy containing Ta is formed as a film.

  Furthermore, a thin film made of another material is deposited on a film containing silicon or silicon nitride as a main component, and a thin film made of another material is formed by dry etching (chemical dry etching CDE) mainly containing fluorine radicals. Over-etching of a film containing silicon or silicon nitride as a main component by laminating a silicon nitride oxide film or silicon oxide film thinner than the silicon or silicon nitride film on the surface of the silicon or silicon nitride film in the patterning step This is solved by a method for manufacturing a thin film functional element, which is characterized by preventing the above.

(Function)
A film containing silicon or silicon nitride as a main component is etched by either RIE or CDE. Therefore, a silicon nitride oxide film or silicon oxide film that is difficult to be etched by CDE is formed on the surface of a film containing silicon or silicon nitride as a main component. By thinly depositing, it becomes possible to improve the controllability of the etching process and reduce the damage to the film while maintaining the physical properties of the film mainly composed of silicon nitride.

  As described above, according to the present invention, a silicon nitride oxide film or a silicon oxide film thinner than a silicon nitride film as an etching stop layer of CDE is applied to a thin film functional element in which a film containing silicon or silicon nitride as a main component is laminated. By using this, over-etching of a film containing silicon or silicon nitride as a main component is suppressed in the CDE process of the upper functional film, and the device yield and reliability are improved.

(Experiment 1)
Below, the experiment concerning this invention is described.

1 and 3 show the configuration of the sample used in this experiment. In FIG. 1, a 200 nm plasma CVD SiON film (composition Si 34%, O 59%, N 3%) 103 is deposited on a Si substrate 101 on the surface of a plasma CVD SiN102 film 3000A, and Ta and Ta are deposited thereon. In this configuration, a resist is placed. In FIG. 3, 3000 A of SiN film 102 by plasma CVD is deposited, 3000 A of Ta103 is deposited thereon, and a pattern 105 is formed thereon with a resist. These Ta were etched by CDE. Etching conditions were CF ₄ / O ₂ / N ₂ = 300/150/50 sccm, pressure 55 Pa, and RF = 0.8 KW.

  2 and 4 show the cross section after etching. In FIG. 2, the Ta underlayer film is only etched by about 50 A, whereas in FIG. 4, overetching by about 600 A was observed.

(Experiment 2)
Below, the experiment concerning this invention is described.

5 and 7 show the configuration of the sample used in this experiment. FIG. 5 shows that a plasma CVD SiON film (composition Si 35%, O 55%, N 8%) 203 is deposited on the surface of 3000A of the plasma CVD SiN film 202 by 300A, and Al205 is deposited by 2000A and patterned. On top of this, 4000 A of SiN 204 was deposited, and a pattern 206 was formed with a resist on the top. FIG. 7 shows a structure in which Al, SiN, and a resist are placed on the surface of a plasma CVD SiN film 3000A as in FIG. These upper SiN layers were etched by CDE. Etching conditions were CF ₄ / O ₂ / N ₂ = 300/250/50 sccm, pressure 60 Pa, and RF = 0.8 KW.

  6 and 8 show a cross section after etching. In FIG. 6, the Al underlayer film is only etched by about 100 A, whereas in FIG. 8, overetching by about 800 A was observed.

(Experiment 3)
Next, the etching rate for CDE was examined by changing the composition of the SiON film. The CDE conditions at this time were CF ₄ / O ₂ / N ₂ = 300/250/50 sccm, pressure 60 Pa, and RF = 0.8 KW.

  Table 1 shows the relationship between the composition ratio of Si, O, and N and the etching rate. It can be seen that when the concentration of O is 40% or more, the etching selectivity with SiN is increased.

(Example embodiment)
FIG. 1 is a schematic view of a base substrate of a thin film functional device showing an embodiment according to the present invention. Glass, ceramic, metal, Si, resin or the like is used as the substrate.

  The lower film 101 is a layer that requires Si or SiN as a main component in terms of dielectric constant, withstand voltage, etc., and there is no limitation on the composition or film thickness. The upper film 102 is a SiON film and has an O concentration of generally 35% or more, preferably 40% or more, and optimally 50% or more. This functions as a CDE stop layer. The film thickness is preferably as thin as possible so as not to affect the characteristics of the underlying Si or SiN film.

  On the other hand, another film 104 to be etched is deposited on the CDE stop layer. If this is a film etched by CDE, the film type is not particularly limited. When the film thickness is large, it is necessary to take a long over-etching time in consideration of the distribution in the substrate surface, so the CDE stop layer needs to be relatively thick.

  Therefore, if the thickness is not more than a certain level, there is no effect as a CDE stop layer. Although depending on the thickness of the layer to be etched, the thickness of the upper SiON layer is generally 2000 to 3000 mm, preferably 1000 to 2000 mm or more, and optimally 100 to 1000 mm.

  Next, a process example in which the laminated film of SiN and SiON according to the present invention is applied to the process of the ink jet recording nozzle will be described in order with reference to FIGS.

  (1) An insulating film 302 is formed on a silicon substrate 301 having a substrate surface orientation (110) of, for example, thermal oxidation or CVD, and an ink supply port is provided as shown in FIG. 9 (plan view FIG. 27) by photolithography. The desired pattern 303 is formed.

  (2) A metal having a low resistance such as Al or Cu and a high etching rate for an etchant for anisotropic etching such as TMAH (tetra-methyl-ammonium hydride) is deposited and patterned to form a lower wiring 304 and a sacrificial layer 305. Form. The etching sacrificial layer is an etching rate that is much faster than the Si wafer when etching proceeds from the back surface and the etchant reaches the sacrificial layer, so that etching can be performed in a short time and an opening corresponding to the sacrificial layer pattern can be opened. is there. The pattern at this time is a parallelogram with a narrow angle of 70.5 degrees so that an etching hole is perpendicular to the substrate, and the long side and the short side of the parallelogram are on a plane equivalent to (111). Arrange them so that they are parallel.

  (3) An SiN or SiON film is deposited as an etching stop layer 306 on the substrate surface by plasma CVD. As the etching stop layer, two or more kinds of films may be laminated in order to adjust the film stress.

The total thickness of the laminated etching stop film is preferably 2000 to 1 μm, more preferably 3000 to 9000 mm, and most preferably 4000 to 8000 mm. The total stress of the laminated etching stop film is preferably 2 × 10 exp-9 dyne / cm ² or less, more preferably 1.8 × 10 exp-9 dyne / cm ² or less, optimally 1 . Tensile stress of 5 × 10 exp-9 dyne / cm ² or less.

(4) A film such as SiN, SiON, or SiO ₂ is deposited by plasma CVD or the like to form an interlayer insulating film 307. Further, a contact hole 308 is formed in the interlayer insulating film.

  (5) A heater unit 309 is formed as an ink discharge pressure generating element in accordance with the ink supply port. As the heater material, a metal film such as Ta, TaN, TaNSi or the like is deposited and patterned by sputtering, vacuum evaporation or the like. Further, a metal film of Al, Mo, Ni, Cu or the like is formed in the same manner as the upper layer electrode 310 for supplying power.

  (6) A SiN film 311 is deposited on the heater by plasma CVD for the purpose of improving durability to form a protective film.

  (7) Further, SiON is deposited as a CDE stop layer 312 by plasma CVD. The composition at this time is 30 to 40% for Si, 40 to 65% for O, and 0 to 20% for N. The thickness of this film is generally 50 to 2000 mm, preferably 100 to 1000 mm, and optimally 150 to 500 mm.

  (8) Ta is deposited thereon as a cavitation resistant film 313 by sputtering or the like. The thickness of this film is preferably 1000 to 5000 mm, more preferably 2000 to 4000 mm, and most preferably 2500 to 3500 mm.

(9) A pattern is formed on this Ta with a resist and etched by the CDE method. For the etching, a fluorocarbon-based gas such as CF ₄ , C ₂ F ₆ , or CHF _3, or O ₂ or N ₂ is used. At this time, the CDE stop layer 312 functions to prevent the underlying heater protection film 311 from being over-etched.

  Needless to say, there is no particular limitation on the order of forming the wiring and the heater.

  (10) A resin film 314 having high corrosion resistance is formed in order to improve the adhesion of the resin nozzle and to protect the back surface from the alkali etchant. Then, the heater part and the ink supply port part are patterned.

  (11) In order to secure the ink flow path, the pattern 315 is formed of a resin that can be dissolved in a strong alkali or an organic solvent. This pattern is formed by a printing method or patterning with a photosensitive resin.

  (12) A coating resin layer 316 is formed on the ink flow path pattern. Since this coating resin layer forms a fine pattern, a photosensitive resist is desirable, and further, the coating resin layer must have a property of not being deformed and altered by an alkali, a solvent, or the like when the resin layer having the flow path is removed.

  (13) Next, the coating resin layer 316 of the flow path is patterned to form an ink discharge port 317 corresponding to the heater portion 309 and an external connection portion of the electrode. Thereafter, the coating resin layer is cured by light or heat.

  (14) A protective film 318 is formed with a resist to protect the nozzle forming surface side of the substrate.

(15) Using a photolithographic technique, the back surface of the ink supply port pattern portion 319 is removed from the back surface of SiN or SiO ₂ to expose the wafer surface. The pattern is formed so as to have a mirror image relationship with the sacrificial layer (plan view 28). The manufacturing method of the etching mask film on the back surface is not limited to plasma CVD, but may be LPCVD, atmospheric pressure CVD, thermal oxidation, or the like.

  (16) Next, an etching leading hole 320 is opened in the narrow-angle vicinity of the parallelogram on the back surface (plan view 28 on the back surface). Generally, laser machining or the like is used, but electric discharge machining, blasting, or the like may be used.

  This lead hole can be as close as possible to the etching stop layer. The depth of the leading hole is generally 60% or more of the substrate thickness, preferably 70% or more, and optimally 80% or more. Also, it must not penetrate the substrate. By this leading hole, the oblique (111) plane generated from the narrow angle of the parallelogram is suppressed.

  (17) When this substrate is immersed in an alkaline etchant (KOH, TMAH, hydrazine, etc.) and anisotropic etching is performed so that the (111) plane appears, the planar shape is a parallelogram (rectangular in the case of (100) substrate). A through hole is formed.

  (18) A film such as SiN of the etching stop layer 306 is partially removed by a chemical solution such as hydrofluoric acid or dry etching to open an ink supply port. Finally, the ink flow path forming material 315 is removed to secure the ink flow path 322.

  In the above process, the substrate processing procedure is not particularly limited, and can be arbitrarily selected.

  FIG. 2 shows a partial cross-sectional structure of a functional element having a CDE stop layer on a SiN film according to the present invention.

  A 6000 A SiN film 102 by LPCVD is deposited on a 5-inch Si wafer 101, and 200 A SiON film 103 by plasma CVD is formed thereon as a CDE stop layer. The composition of the SiON film was 38 for Si, 41% for O, and 21% for N.

  Further, 4000 nm of SiN film is deposited by plasma CVD, patterned by resist, and then etched by CDE method to leave the SiN film pattern 106.

  FIG. 29 shows a partial cross-sectional structure of a functional element having a CDE stop layer on a poly-Si film according to the present invention.

  A poly-Si film 402 by LPCVD is deposited on a 50 mm square alumina substrate 401 by 1 μm, and a 300 A SiON film 403 by plasma CVD is formed thereon as a CDE stop layer. The composition of the SiON film was 34 for Si, 58% for O, and 8% for N.

  On top of this, a 5000-SiN film is deposited by plasma CVD, a pattern is formed by a resist, and etching is performed by a CDE method to leave a SiN pattern 404.

  FIG. 26 shows a cross-sectional structure of an ink jet recording head as an example of a functional element having a CDE stop layer on a SiN film according to the present invention.

On a 5-inch Si wafer, a SiO ₂ heat storage layer 302 of 7000 mm, an Al lower layer wiring 304 of 2000 mm, an SiON film 307 of 4000 A by plasma CVD as an interlayer insulating film are deposited, a TaNSi heater film 309 of 500 A, an Al upper layer The wiring 310 is 3000 Å, the SiN film 3000 の of plasma CVD is formed as the heater protection film 311, and a 200 A SiON film is formed as the CDE stop layer 312 by the plasma CVD method. The composition of the SiON film was 35% for Si, 52% for O, and 13% for N. Further, a cavitation-resistant film 313 having a Ta film of 1000 mm, a polyetheramide resin (HIMAL Hitachi Chemical) of 2 μm as the adhesion improving resin film 314, and a photosensitive resist shown in Table 2 as the nozzle forming resin 316 of 16 μm are used immediately above the heater. A nozzle 317 was formed.

  The process flow of the embodiment of the ink jet recording nozzle according to the present invention will be described step by step with reference to FIGS.

(1) A silicon substrate 301 having 330 × 150 mm thickness 0.9 mm, substrate surface orientation (110), short side orientation (211), and long side orientation (111) is coated with SiO ₂ 302 by thermal oxidation. 14000 mm was formed, and a desired pattern 303 for providing an ink supply port was formed as shown in FIG. 9 (plan view FIG. 27) by photolithography.

  (2) 2000Å Al99.5Cu0.5 was deposited and patterned to form a lower layer wiring 304 and a sacrificial layer 305. The etching sacrificial layer is an etching rate that is much faster than the Si wafer when etching proceeds from the back surface and the etchant reaches the sacrificial layer, so that etching can be performed in a short time and an opening corresponding to the sacrificial layer pattern can be opened. is there. The pattern at this time is a parallelogram with a narrow angle of 70.5 degrees so that an etching hole is perpendicular to the substrate, and the long side and the short side of the parallelogram are on a plane equivalent to (111). Arrange them so that they are parallel.

  The long side of the sacrificial layer was 3 mm, and the width was 160 μm.

  (3) An etching stop layer 306 was obtained by depositing and patterning a 6000-SiN film on the substrate surface by plasma CVD.

  (4) Using plasma CVD, an SiN film was deposited by 7000 mm to form an interlayer insulating film 307. Further, a contact hole 308 is formed in the interlayer insulating film using dry etching.

  (5) An ink discharge pressure generating heater unit 309 was formed by depositing and patterning 600 μm of TaSiN in accordance with the ink supply port. Further, an AlCu film was formed as an electrode 310 for power supply.

  (6) Next, 3000 nm of plasma CVD SIN was deposited and patterned as the heater protective film 311.

  (7) Further, SiON is deposited as a CDE stop layer 312 by plasma CVD. The composition at this time was 35% for Si, 55% for O, and 8% for N. The film thickness was 150 mm.

  (8) In order to protect the heater from cavitation due to ink foaming, 3000 liters of Ta was deposited and patterned to form a cavitation-resistant film 313.

  (9) In order to increase the adhesion of the resin nozzle and to protect the back surface from the alkali etchant, a polyetheramide resin film (HIMAL manufactured by Hitachi Chemical Co., Ltd.) 314 having a high corrosion resistance is formed by applying and firing 2 μm. The heater part and the ink supply port part were exposed by patterning.

  (10) In order to secure the ink flow path, a resin polymethylisopropenyl ketone (Tokyo Ohka ODUR-1010) 315, which can be dissolved in a strong alkali or an organic solvent, was patterned using lithography.

  (11) An ink flow path covering resin layer 316 was formed on the ink flow path pattern using the photosensitive resin shown in Table 2.

  (12) Next, the coating resin layer of the flow path is patterned to form the ink discharge port 317 corresponding to the heater portion and the external connection portion of the electrode. Thereafter, the coating resin layer was cured by heat.

  (13) A protective film (OBC Tokyo Ohka) 318 is formed with a corrosion resistant resist to protect the nozzle forming surface side of the substrate.

  (14) The pattern portion 319 of the ink supply port is removed from the back surface of the resin protective film and the insulating film using a photolithographic technique to expose the wafer surface. The pattern is formed so as to have a mirror image relationship with the sacrificial layer as shown in FIG.

  (15) Next, an etching leading hole 320 was opened using a YAG laser in a narrow-angle vicinity portion of the parallelogram on the back surface (plan view 28 on the back surface).

  This lead hole can be as close as possible to the etching stop layer. By this leading hole, the oblique (111) plane generated from the narrow angle of the parallelogram is suppressed.

  (16) This substrate was immersed in TMAH (tetramethylammonium hydride) for 9 hours and anisotropically etched so that the (111) plane appeared.

  A through-hole having a parallelogram shape in plan view is formed.

  (17) As shown in FIG. 24, the SiN film of the etching stop layer 306 was partially removed by CDE (chemical dry etching) to open the ink supply port 321.

  (18) The protective film 318 is removed as shown in FIG. 25, and finally the ink flow path forming material is removed to secure the ink flow path 322.

  Using this ink jet recording head, a printing test was performed for 500 hours at an ejection frequency of 6 KHz. A high-quality printed matter free from printing blur, density unevenness, and non-ejection of ink was obtained over the entire 270 mm width.

(Comparative Example 1)
When the inkjet recording head was formed in the same process as in Example 4 except that the CDE stop layer 312 was not formed, overetching occurred in a part of the SiN protective film 311 during the CDE of the Ta film. A nozzle that cannot eject ink was generated in 20 hours.

(Comparative Example 2)
An ink jet recording head was formed in the same process as in Example 4 except that the SiC film 200 し た having the CDE stop layer 312 formed by sputtering. When an ink ejection experiment was conducted for 10 hours, the Ta film and the protective film 311 / Part of the film was peeled off between the CDE stop layers 312 and nozzles that could not eject ink were generated.

(Comparative Example 3)
An ink jet recording head was formed in the same process as in Example 4 except that the CDE stop layer 312 was formed by sputtering, and a Ta film and a protective film 311 / Part of the film was peeled off between the CDE stop layers 312 and nozzles that could not eject ink were generated.

  In the following, another embodiment of the present invention will be described.

The CDE stop layer 312 was made of a plasma CVD SiO ₂ film 100 mm, and an ink jet recording head was formed in the same process as in Example 4.

  Using this inkjet recording head, a printing test was conducted for 500 hours at an ejection frequency of 5 KHz. A high-quality printed matter free from printing blur, density unevenness, and non-ejection of ink was obtained over the entire width of 270 mm.

Schematic showing configuration and process of functional substrate according to the present invention Schematic showing configuration and process of functional substrate according to the present invention Schematic showing the configuration of the functional substrate of the comparative example Schematic showing the configuration of the functional substrate of the comparative example Schematic showing configuration and process of functional substrate according to the present invention Schematic showing configuration and process of functional substrate according to the present invention Schematic showing the configuration of the functional substrate of the comparative example Schematic showing the configuration of the functional substrate of the comparative example The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing-process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention The figure which shows the manufacturing process flow of the inkjet recording head by this invention Schematic showing configuration and process of functional substrate according to the present invention

Explanation of symbols

101 Substrate 102 SiN film 103 SiON film 104 Etched film 105 Resist 201 Substrate 202 SiN film 203 SiON film 204 SiN film 205 Al
206 Resist 301 Substrate 302 Insulating film 303 Ink supply port pattern 304 Lower electrode 305 Sacrificial layer 306 Etching stop layer 307 Interlayer insulating film 308 Contact hole 309 Heater 310 Upper layer electrode 311 SiN protective film 312 SiON film 313 Ta cavitation film 314 Resin film 315 Ink channel forming member 316 Nozzle forming resin 317 Ejection port 318 Etching protective film 319 Ink supply port 320 Laser processing leading hole 321 Ink supply port 322 Ink channel 401 Alumina substrate 402 Polysilicon film 403 SiON film 404 SiN film

Claims (17)

  A thin film functional element in which a film composed mainly of silicon nitride is laminated in a constituent material, and a silicon nitride oxide film or silicon oxide film thinner than the silicon nitride film is laminated on the surface of the silicon nitride film A thin film functional element characterized by   A thin film functional element in which a film containing silicon as a main component is laminated in a constituent material, wherein a thin silicon nitride oxide film or a silicon oxide film is laminated on the surface of the silicon film .   2. The thin film functional element according to claim 1, wherein the thin silicon nitride oxide film or silicon oxide film is 2000 A or less.   2. The thin film functional element according to claim 1, wherein the thin silicon nitride oxide film or silicon oxide film is 500 A or less.   2. The thin film functional element according to claim 1, wherein the thin silicon nitride oxide film or the silicon oxide film has an oxygen concentration of 40 atm% or more in the film.   2. The thin film functional element manufacturing method according to claim 1, wherein the thin silicon nitride oxide film or silicon oxide film is deposited by plasma CVD.   A film mainly composed of silicon nitride is deposited as a heater protective film for an ink jet recording head, a silicon nitride oxide film or a silicon oxide film thinner than the silicon nitride film is laminated on the surface, and a cavitation-resistant film is further formed thereon. An ink jet recording head, wherein a film of Ta or an alloy containing Ta is formed.   7. The ink jet recording head according to claim 6, wherein the thin silicon nitride oxide film or silicon oxide film is 2000 A or less.   7. The ink jet recording head according to claim 6, wherein the thin silicon nitride oxide film or silicon oxide film is 500 A or less.   7. The ink jet recording head according to claim 6, wherein the thin silicon nitride oxide film or the silicon oxide film has an oxygen concentration of 40 atm% or more in the film.   8. The method according to claim 7, wherein the thin silicon nitride oxide film or silicon oxide film is deposited by plasma CVD.   In the process of depositing a thin film of another material on a film mainly composed of silicon nitride, and patterning the thin film of another material by dry etching (chemical dry etching CDE) mainly including fluorine radicals. A thin film function characterized in that a silicon nitride oxide film or a silicon oxide film thinner than the silicon nitride film is laminated on the surface of the silicon nitride film to prevent over-etching of the film mainly composed of silicon nitride Device manufacturing method.   11. The method of manufacturing a thin film functional element according to claim 10, wherein the thin silicon nitride oxide film or silicon oxide film is 2000 A or less.   11. The method of manufacturing a thin film functional element according to claim 10, wherein the thin silicon nitride oxide film or silicon oxide film is 500 A or less.   In a series of steps for forming an ink ejection element on a silicon substrate, forming a film mainly composed of silicon nitride as an insulating layer and an etching stop layer, and forming another film on the film mainly composed of silicon nitride. And a step of selectively etching the silicon nitride film by chemical dry etching (CDE), wherein a silicon nitride oxide film or a silicon oxide film thinner than the film is formed on the surface of the film containing silicon nitride as a main component. A method of manufacturing an ink jet recording head, characterized in that over-etching of a film mainly composed of silicon nitride is prevented by laminating layers.   14. The method of manufacturing an ink jet recording head according to claim 13, wherein the film to be selectively etched is a heater protective film mainly composed of a silicon nitride film.   14. The method of manufacturing an ink jet recording head according to claim 13, wherein the film to be selectively etched is a cavitation resistant film having a Ta film as a main component.

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