JP4534622B2 - Functional element and manufacturing method thereof, fluid discharge head, and printing apparatus - Google Patents

Description

  The present invention relates to a functional element having a hollow structure portion, a manufacturing method thereof, and a fluid discharge head and a printing apparatus configured using the functional element.

  In recent years, functional elements having a hollow structure formed by a thin film forming technique are being used. The “thin film formation technique” refers to a technique for forming a thin film by performing vapor deposition, sputtering, etching, or the like, for example, as used when performing fine processing on a silicon semiconductor substrate in a semiconductor manufacturing process. The “functional element having a hollow structure part” means an element in which the internal element of the hollow structure part or the inner surface or surface of the structure part shows some response to an input signal. In addition, a case where any gas, liquid, or solid is injected into the hollow structure portion is included. The hollow structure portion may be completely sealed or may be partially opened. Examples of such functional elements are fluid ejection devices such as inkjet heads, micropumps, μTAS (Micro Total Analysis Systems), DNA chips, frequency filters, switches such as various sensors and relays, etc. So-called MEMS (Micro Electro Mechanical Systems) are known. However, the functional element here is not only a MEMS but also a semiconductor element, a resonator, a vibrator, an FBAR (Film Bulk Acoustic Resonator), a SAW (surface acoustic wave) filter, Gyro sensor, liquid crystal element, organic electroluminescence element, resistance element, relay element, LED (Light Emitting Diode), laser element, FED (Field Emission Display) and other light source elements, speaker element, diaphragm type sensor (eg, microphone, pressure) Sensor), flow path, tube, imaging device, and the like.

  By the way, in the functional element described above, the hollow structure portion is generally formed by sealing the opening used for the removal after removing the sacrificial layer. Specifically, for example, when a diaphragm type semiconductor device is taken as an example, it is known to form in the following procedure (for example, see Patent Document 1). That is, a first etching resistant layer is laminated on the surface of the silicon substrate, and an etching layer that becomes a sacrificial layer is laminated in a predetermined region on the surface of the first etching resistant layer. And after laminating | stacking the 2nd etching-resistant layer which has many fine openings on the surface of the etching layer, an etching layer is etched from the opening group of a 2nd etching-resistant layer. As a result, a space is formed between the first etching resistant layer and the second etching resistant layer. After the formation of the space, a sealing film is laminated on the surface of the second etching resistant layer to seal a small opening group of the second etching resistant layer. Through the above procedure, a diaphragm structure is realized in which a diaphragm is formed by the second etching resistant layer and the sealing film, and a sealed space serving as a hollow structure portion is formed inside the diaphragm.

Japanese Patent Laid-Open No. 2002-343979

  However, in the conventional functional element, there is a possibility that voids (bubbles) are generated when the opening is sealed to form the hollow structure portion. This is because, for example, the residue at the time of opening formation that remains on the side wall of the opening generates gas due to the temperature rise during the formation of the sealing film, or a shadow is created and a void remains (shadowing effect) This is because the sealing film is not easily formed in the vicinity of the opening (the film forming material is difficult to deposit on the side wall of the opening). The generation of such voids should be avoided because it makes the sealing of the opening incomplete, makes it difficult to form the hollow structure part, and leads to the functional deterioration of the functional element. .

  Therefore, the present invention makes it possible to reliably seal the opening even when the opening is sealed after the sacrificial layer is removed to form a hollow structure, and the function can be reliably realized by the hollow structure. It is an object of the present invention to provide a functional element that can be realized, a manufacturing method thereof, an ink jet head, and an ink jet printer apparatus.

The present invention is a functional device devised to achieve the above object. That is, in a functional element having a hollow structure portion formed by sealing an opening, a cross-sectional shape of the opening is formed in a tapered shape in which the diameter of the opening narrows toward the hollow structure portion, and at least The hollow structure portion facing the opening from the opening by forming a protective layer on the tapered inclined surface portion of the opening, forming a sealing film in the protective layer of the tapered inclined surface and the region of the opening A part of the hollow structure portion is sealed by laminating the sealing film on the surface .

Moreover, this invention is the manufacturing method of the functional element devised in order to achieve the said objective. That is, in a method of manufacturing a functional element having a hollow structure portion formed by sealing an opening, the cross-sectional shape of the opening is formed in a tapered shape in which the diameter of the opening becomes narrower toward the hollow structure portion. A step of laminating a protective layer on at least the tapered inclined surface in the opening, forming a sealing film on the protective layer of the tapered inclined surface and the opening, and from the opening to the opening A step of sealing a part of the hollow structure part by laminating the sealing film on the surface of the opposing hollow structure part .

The present invention is also a fluid ejection head devised to achieve the above object. That is, in a fluid discharge head configured using a functional element having a hollow structure portion formed by sealing the opening, the cross-sectional shape of the opening has a diameter of the opening toward the hollow structure portion. Formed into a tapered shape that becomes narrower , a protective layer is laminated at least on the tapered inclined surface in the opening, and a sealing film is formed in a region of the protective layer on the tapered inclined surface and the opening, from the opening. A part of the hollow structure portion is sealed by laminating the sealing film on the surface of the hollow structure portion facing the opening .

The present invention is also a printing apparatus devised to achieve the above object. That is, in a printing apparatus configured using a functional element having a hollow structure portion formed by sealing the opening as a fluid discharge head, the cross-sectional shape of the opening is directed toward the hollow structure portion. Forming a sealing layer in the region of the opening and the protective layer of the tapered inclined surface, the protective layer is laminated at least in the tapered inclined surface of the opening, A part of the hollow structure part is sealed by laminating the sealing film on the surface of the hollow structure part facing the opening from the opening .

  According to the functional element having the above configuration, the method for manufacturing the functional element having the above procedure, the fluid ejection head having the above configuration, and the printing apparatus having the above configuration, the cross-sectional shape of the opening is formed in a tapered shape. That is, the opening is formed so that the diameter of the opening becomes narrower toward the hollow structure portion. Here, the “diameter” of the opening means the diameter of the opening if the opening is circular, but is not necessarily limited to this, and includes, for example, the length of one side of the rectangular opening. It is. If the opening is formed in such a tapered shape, even if there is a residue at the time of forming the opening on the tapered inclined surface, the residue is easier than in the case where the side wall portion of the opening is a vertical surface. Can be removed. Also, when the opening is sealed by forming a sealing film, it is easier to deposit the film forming material for the sealing film than when the side wall portion of the opening is a vertical surface. Therefore, generation of voids when sealing the opening can be avoided, and the opening can be reliably sealed.

  In the present invention, even when the opening is sealed after the sacrificial layer is removed to form the hollow structure portion, void formation is avoided and the opening can be reliably sealed. As a result, it is possible to ensure the function realization. This can be said to lead to improvement in performance (function) and reliability of the functional element. In addition, in a device such as a filter that requires airtightness, the sealing (package) cost often accounts for more than half of the product price. There is a great need for level packaging technology, and it can be said that the technical value of the present invention that can realize this is high. In addition, by realizing wafer level packaging, it can be expected that device miniaturization (high integration) can be easily realized.

  Hereinafter, a functional element and a manufacturing method thereof, a fluid discharge head, and a printing apparatus according to the present invention will be described with reference to the drawings.

[Description of functional elements]
First, a schematic configuration of the functional element will be described. As described above, the functional element includes all of the elements having the hollow structure portion, and an example thereof is shown in FIG. FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a functional element according to the present invention.

  As shown in the figure, the functional element 1 described here has a hollow structure portion 2. By having the hollow structure portion 2, in the functional element 1, the layer covering the hollow structure portion 2 constitutes a diaphragm, and a voltage can be applied to an electrode (not shown) so that the diaphragm can be vibrated. It becomes.

  The hollow structure portion 2 is formed by so-called sacrificial layer etching. That is, an etching layer serving as a sacrificial layer is laminated at a place where the hollow structure portion 2 is formed, and further an etching resistant layer 4 having an opening 3 is laminated on the surface of the etching layer, and the etching layer is etched from the opening 3. After the removal, the opening 3 used for the removal is sealed.

  The opening 3 is sealed by forming a sealing film 5 at the formation location. It is conceivable that the opening 3 is sealed by the sealing film 5 by vapor deposition, sputtering, or PECVD (plasma-enhanced chemical vapor deposition). In particular, it is desirable to carry out by metal sputtering. If there is a film formation on the hollow structure portion 2 during the sealing process, the device characteristics of the functional element 1 may be changed, but this problem is lessened by sputtering. However, not only in the case of sputtering, but also in the case of vapor deposition or PECVD, sealing can be performed by a series of film forming processes. Therefore, for example, compared with the case where the opening 3 is sealed by bonding members. In this case, the sealing is very easy and reliable. Moreover, since vapor deposition, sputtering, and PECVD are all performed in a vacuum chamber, they are very effective in favorably maintaining the internal environment of the hollow structure portion 2.

  A cover layer 6 may be formed on the sealing film 5 to prevent intrusion of outside air or fluid. This is because if the sealing film 5 is covered with the cover layer 6, the sealing of the opening 3 by the sealing film 5 becomes even more reliable. As such a cover layer 6, a plasma silicon nitride (PE-SiN) film that has excellent moisture resistance and is effective in preventing intrusion of fluid or the like can be considered. However, the cover layer 6 is not necessarily a single layer, and may be a multiple layer.

  By the way, if the opening 3 is simply sealed by sputtering, voids are generated due to the shadowing effect as described above, and there is a possibility that an air path that passes between the hollow structure portion 2 and the outside may remain. . From this, in the functional element 1 described here, the cross-sectional shape of the opening 3 is formed in a tapered shape in which the opening diameter becomes narrower toward the hollow structure portion 2. That is, the opening 3 has a tapered inclined surface on the side wall portion. The tapered inclined surface preferably has an angle with respect to the vertical direction (inclination angle) of 30 ° or more. Moreover, the opening diameter here means the diameter of the opening 3 if it is circular, but is not necessarily limited to this. For example, when the opening 3 is rectangular, the length of one side corresponds to the opening diameter here. In that case, it is desirable that all the side wall portions of the opening 3 are tapered inclined surfaces. However, if the opening 3 has the tapered inclined surface, the tapered inclined surface and the vertical surface are mixed. It doesn't matter.

  As described above, in the functional element 1 described here, the opening 3 has a tapered cross-sectional shape. Therefore, even if there is a residue on the tapered inclined surface when the opening is formed, the side wall portion of the opening 3 is formed. Compared with the case where is a vertical surface, the residue can be easily removed. That is, when a by-product remains as a residue on the side wall, a gas is generated due to a temperature rise during the formation of the sealing film 5 and a void is generated, but even when the residue cannot be removed by ashing or cleaning, A tapered inclined surface can be easily removed by etchback, reverse sputtering, or the like. In addition, it is possible to suppress the shadowing effect, that is, the absence of a tapered inclined surface and the formation of a shadow portion and a void remaining. In addition, when the opening 3 is sealed by forming the sealing film 5, the film forming material for the sealing film 5 is deposited as compared with the case where the side wall portion of the opening 3 is a vertical surface. It becomes easy. The sealing film 5 formed on the tapered inclined surface naturally grows in a direction to fill the opening 3. These are particularly noticeable when the inclination angle of the tapered inclined surface is 30 ° or more. Therefore, if the cross-sectional shape of the opening 3 is formed in a tapered shape, generation of voids when the opening 3 is sealed can be avoided, and the opening 3 can be reliably sealed without leaving an air path. It becomes.

  However, as described above, even if the sectional shape of the opening 3 is simply formed in a tapered shape, the size (hereinafter referred to as “gap height”) of the hollow structure portion 2 in the height direction (stacking direction of each layer) is referred to. ) Is small, the opening 3 can be reliably sealed as shown in FIG. 2A, but when the gap height is increased, the opening 3 is sealed as shown in FIG. 2B. May become difficult. This point may be dealt with by narrowing the gap height by selective oxidation, but this method of increasing the film pressure by thermal oxidation causes the process temperature to exceed 800 ° C., and the device characteristics of the functional element 1 are improved. Since it changes with this temperature, it is not preferable. In addition, if such a high temperature process is performed after the formation process of transistors, wirings, and the like, transistor characteristics deteriorate, and heat locks are generated in aluminum (Al) and copper (Cu), thereby reducing the reliability of the functional element 1. Therefore, the high temperature process is not preferable in this respect as well. On the other hand, it is conceivable to grow the oxide film at a low temperature. However, in this case, a very long time is required, which is difficult in terms of process efficiency.

  Therefore, in the functional element 1 described here, as shown in FIG. 1, the protective layer 7 is laminated on the tapered inclined surface portion in the opening 3, and the protective layer 7 is overetched with respect to the sacrificial layer. It is also laminated on the part 8. The protective layer 7 is desirably formed of an insulating material that is a forming material that takes the sealing film 5 into account (for example, a material having high affinity with the sealing film 5). In order to satisfy such conditions, the protective layer 7 does not necessarily need to be a single layer, and may be a multilayer. The protective layer 7 only needs to be stacked on at least the tapered inclined surface, but it is needless to say that the protective layer 7 may be stacked on other than the tapered inclined surface. The over-etched portion 8 with respect to the sacrificial layer refers to a portion where not only the etching resistant layer 4 but also the etching layer serving as the sacrificial layer is removed by etching when the opening 3 is formed.

  In this way, if the single-layer or multi-layer protective layer 7 is laminated, the protective layer 7 covers a portion of the tapered inclined surface in the opening 3, so that the tapered inclined surface is removed. Even if there is a residue that cannot be removed, it can be suppressed as much as possible that the residue causes a void when the opening 3 is sealed. In addition, if the protective layer 7 is formed of a forming material that takes the sealing film 5 into account, the film forming material of the sealing film 5 formed by, for example, metal sputtering can be easily deposited on the protective layer 7. As a result, the sealing of the opening 3 with the sealing film 5 can be realized. At the same time, unnecessary etching is less likely to occur.

  Further, if the single-layer or multi-layer protective layer 7 is laminated, it is possible to form the sealing film 5 after forming the over-etched portion 8, that is, over-etching the sacrificial layer. If the over-etched portion 8 is formed, the gap height when the sealing film 5 is formed and the opening 3 is sealed is controlled as shown in FIG. Control), and even if the gap height of the hollow structure portion 2 is large, the opening 3 can be reliably sealed. That is, even if the gap height of the hollow structure portion 2 is large, the substantial gap height when sealing the opening 3 is sealed by forming the over-etched portion 8. The film 5 can be reduced to a size that can be sealed. Therefore, although the gap height of the hollow structure portion 2 is determined by the function realized by the functional element 1, device characteristics, and the like, it is possible to realize reliable sealing of the opening 3 regardless of the gap height. It is.

[Description of Method for Manufacturing Functional Element]
Next, a method for manufacturing the functional element 1 configured as described above will be described. However, here, the formation of the opening 3 and the sealing procedure will be mainly described. 3-4 is explanatory drawing which shows the outline | summary of the manufacturing method of the functional element based on this invention.

For example, the opening 3 is formed on a stacked body in which a polysilicon film 12 serving as a sacrificial layer (etching layer) is stacked on a semiconductor silicon substrate 11 and a silicon nitride film 13 serving as an etching resistant layer is stacked. Then, after forming the resist film 14 patterned according to the opening formation position, isotropic etching is used. In this isotropic etching, ashing is performed by introducing oxygen (O ₂ ) in addition to an etching gas such as carbon tetrafluoride (CF ₄ ), and etching is performed while the resist film 14 is retracted. As a result, as shown in FIG. 3A, the silicon nitride film 13 can be etched with a wider opening angle than in the case of simple isotropic etching.

  Thereafter, reactive ion etching (hereinafter referred to as “RIE”) is performed, and as shown in FIG. 3B, the side wall surface of the etched portion in the silicon nitride film 13 is an inverted R curved surface (concave shape). The curved surface of the polysilicon film 12 is changed to a tapered inclined surface (tapered inclined surface narrowing toward the polysilicon film 12 side), and the remaining film thickness of the polysilicon film 12 is high enough to be sealed. The polysilicon film 12 is sufficiently over-etched to a thickness corresponding to the thickness.

  The inclination angle of the tapered inclined surface and the depth of overetching can be controlled to a desired angle and depth by appropriately adjusting processing parameters (processing time, processing conditions, etc.) during isotropic etching or RIE. Is possible.

  After overetching the polysilicon film 12, thereafter, as shown in FIG. 3C, the resist film 14 is removed and a silicon oxide film 15 serving as a protective layer is formed. Then, a new resist film 16 is stacked, and after patterning the resist film 16 corresponding to the opening formation position, so-called sacrificial layer etching is performed to remove the polysilicon film 12.

  After that, after removing the resist film 16, the sealing film 17 is formed by performing vapor deposition, sputtering or PECVD as shown in FIG. 4A in order to seal the opening used for the sacrifice layer etching. Film. At this time, since the opening has a tapered inclined surface, generation of voids when sealing with the sealing film 17 can be avoided, and reliable sealing without leaving an air path is possible. Become. In addition, the protective layer 15 is laminated on the tapered inclined surface portion, and the protective layer 15 is also laminated on the portion where the polysilicon film 12 is over-etched to the sealable gap height. Therefore, the sealing can be performed regardless of the gap height of the hollow structure portion.

  By the way, since the film thickness of the sealing film 17 is inevitably increased with the opening sealing, as shown in FIG. 4B, portions other than the opening sealing part are removed by patterning. It doesn't matter. However, in that case, it is conceivable that the interface with the base layer is exposed by the removal of the sealing film 17, and the outside air enters the gap of the hollow structure portion through the interface. Therefore, when the sealing film 17 is removed by patterning, the thinnest possible film (for example, the silicon oxide film 15) is left on the entire exposed surface, or the cover layer is removed after the etching of the sealing film 17 is removed. It is desirable to form a film and overcoat. In the former (in the case of leaving the film), even if there is a difference in the thickness of the sealed film, the entire surface is covered and no interface is generated. However, the remaining film is preferably an insulating film. On the other hand, in the latter case (when overcoating), the sealing film 17 is left only in the vicinity of the opening by patterning, and the sealing film 17 is removed in other places to form an interface, so that this is covered with a separate cover layer. It is. In this case, the cover layer is preferably an insulating film having a thickness of 100 nm or more.

  If the opening is formed and sealed in the above-described procedure, a high-temperature process is unnecessary, and manufacturing is possible at 300 ° C. or lower. Therefore, even after the formation process of transistors, wirings, etc. In such a case, the reliability of the functional element due to the high-temperature process is not reduced.

  In the above-described series of procedures, the case where the tapered inclined surface is formed by using isotropic etching and RIE is taken as an example. In addition, the resist film opening is formed by a halftone mask, three-dimensional lithography, or the like. It is conceivable to form a tapered inclined surface by making the wall tapered in advance and appropriately setting the etching rate ratio with the resist film. Further, even if the opening is performed only by RIE without performing isotropic etching, it is possible to form a tapered inclined surface by proceeding with etching while forming a by-product on the side wall.

  In the above-described series of procedures, the case where taper etching is performed when forming an opening in the silicon nitride film 13 is taken as an example, but an opening for sacrificial layer etching is formed in the silicon oxide film 15 serving as a protective layer. Also in this case, if the silicon oxide film 15 is thick, a taper-like inclined surface is formed by taper etching, so that the sealing with the sealing film 17 is easy and reliable.

[Description of fluid ejection head and printing apparatus]
Next, a fluid ejection head and a printing apparatus configured using the functional element 1 as described above will be described.

  First, the printing apparatus will be described. As an example of the printing apparatus, an ink jet printer apparatus is known. FIG. 5 is an explanatory diagram showing an outline of the ink jet printer apparatus. The ink jet printer device prints and outputs a photo-quality printed matter at a high speed by discharging ink onto a sheet in a fine granular form. Such an ink jet printer apparatus is roughly classified into a serial head type and a line head type.

In the case of the serial head type, as shown in FIG. 5A, a paper 22 as a printing object is mounted on a roller 22 that feeds the paper 21 in the main scanning direction, and a carriage 23 that can move in the sub-scanning direction of the paper 21. The inkjet head 24 is provided. The inkjet head 24 ejects ink onto the paper 21 while moving the paper 21 and the carriage 23, thereby performing print output.
On the other hand, in the line head type, as shown in FIG. 5B, the roller 22 for feeding the paper 21 in the main scanning direction and the ink discharge ports in a line shape along the sub-scanning direction of the paper 21. The inkjet head 25 is provided. Then, printing is performed by ejecting ink from each ejection port of the inkjet head 25 onto the paper 21 while moving the paper 21.
Note that the above-described configuration of the ink jet printer apparatus is an example of a printing apparatus, and the configuration is not particularly limited as long as printing can be performed by changing the relative positions of a head unit that ejects fluid and a printing object.

  By the way, in order to meet the need to print even higher image quality at high speed, whether it is a serial head or a line head system, the inkjet printer device does not increase power consumption, but reduces the ejection performance. In addition, it is required to further increase the number of pixels. In order to meet such a demand, some inkjet printer apparatuses are configured using inkjet heads 24 and 25 based on electrostatic MEMS. In the electrostatic MEMS system, the inkjet heads 24 and 25 are configured using the functional elements as described above, and the vibration of the functional elements is used as pressure application means, so that the ink on the paper 21 can be applied. The discharge is performed. It should be noted that constituent elements other than the ink jet heads 24 and 25 in the ink jet printer apparatus may be realized by a publicly known technique, and the description thereof is omitted here.

  Next, an ink jet head used in an ink jet printer apparatus, that is, an ink jet head which is an example of a fluid discharge head configured using the functional elements described above will be described. However, here, only the main part of an ink jet head as a fluid ejection head configured using the above-described functional elements will be described regardless of whether the serial head method or the line head method is used. 6 to 8 are schematic views showing an example of the configuration of the main part of the fluid discharge head according to the present invention. FIG. 6 is a perspective view thereof, FIG. 7 is a plan view thereof, and FIG.

  As shown in FIG. 6, the inkjet head described here includes a microfluidic drive unit 30 and a fluid supply unit 40. The microfluidic drive unit 30 is formed by arranging a plurality of diaphragms 31 driven (vibrated) by electrostatic force in parallel at high density. On the other hand, the fluid supply unit 40 is disposed at a corresponding position on each diaphragm 31 and serves as a pressure chamber (so-called cavity) 42 in which ink 41 as fluid is stored, and an outer wall for forming the pressure chamber 42. The partition structure 43 and a discharge portion (so-called nozzle) 44 for discharging the ink 41 in the pressure chamber 42 to the outside are provided.

  7 and 8, the microfluidic drive unit 30 has a common substrate side electrode 33 made of a conductive material thin film formed on a substrate 32, and an insulating film on the surface of the substrate side electrode 33. A plurality of diaphragm-side electrodes 35 and diaphragms 31 that are independently driven with a hollow structure space (hereinafter referred to as “hollow structure portion”) 34 interposed therebetween so as to face the substrate-side electrode 33 are integrally formed. In addition, the support column 36 is formed on the substrate 32 so as to be arranged in parallel and further to support each diaphragm 31 with a doubly supported beam.

  Of these, the substrate 32 may be, for example, a substrate in which an insulating film 32b made of a silicon oxide film or the like is formed on a silicon substrate 32a. In addition, an insulating film may be formed on a semiconductor substrate such as gallium arsenide (GaAs). It is also possible to use an insulating material such as a glass substrate including a quartz substrate or a glass substrate including a quartz substrate.

  The substrate side electrode 33 may be formed of, for example, a polycrystalline silicon film doped with impurities, but may be a metal film (for example, a deposited film of Pt, Ti, Al, Au, Cr, Ni, Cu, etc.) or ITO (Indium). (Tin Oxide) film or the like may be used. Similarly, the diaphragm side electrode 35 may be formed of an impurity-doped polycrystalline silicon film, a metal film, an ITO film, or the like.

  The diaphragm 31 is formed of an insulating film, but is preferably formed of a silicon nitride film (SiN film) that can obtain a particularly high repulsive force. However, the diaphragm 31 is formed by laminating these respective films, with silicon oxide films formed on the upper and lower surfaces of the SiN film. The diaphragm 31 is formed in, for example, a strip shape, and is supported by a plurality of support columns 36 formed on the both sides thereof at predetermined intervals (pitch between support columns) along the longitudinal direction. The predetermined interval is preferably 2 μm or more and 10 μm or less, and most preferably about 5 μm. The adjacent diaphragms 31 arranged in parallel are continuously formed through the support pillars 36, and the support pillars 36 are also integrally formed of the same material as the diaphragm 31. Therefore, the hollow structure portion 35 constituting the space between the diaphragm 31 and the substrate side electrode 33 is communicated between the plurality of diaphragms 31 arranged in parallel, and is formed to be a sealed space. It will be a thing.

  Further, when performing sacrificial layer etching for forming the hollow structure portion 35 in the vicinity of the struts 36 of each diaphragm 31, specifically, for example, between the struts 36 along the longitudinal direction of one diaphragm 31. An opening 37 to be used is formed. The opening 37 is closed by the sealing film 38 after the sacrifice layer etching. Since the smaller the size of the opening 37 is, the smaller the opening 37 is, the more likely it is to close, □ 2 μm or less may be considered. However, if sacrificial layer etching is dry etching, □ 0.5 μm is sufficient.

  A diaphragm side electrode 35 is bonded to the diaphragm 31 via an insulating film, and the diaphragm side electrode 35 is arranged so as to be inserted into the bent lower surface recess of the diaphragm 31. It shall be installed. Further, below the diaphragm 31, in order to increase the repulsive force when the diaphragm 31 is thinly formed, an auxiliary strut (so-called post) 39 is provided in the vicinity of the center portion together with the strut (so-called anchor) 36. May be formed (see, for example, FIG. 6).

  With respect to such a microfluidic drive unit 30, a fluid supply unit 40 is disposed so that a partition wall 43a in the partition wall structure 43 is formed at a position corresponding to the support column 36 of the diaphragm 31, and an ink jet head is configured. It is. Note that a fluid supply path (not shown) communicates with the pressure chamber 42 of the fluid supply unit 40 disposed on the microfluidic drive unit 30 in order to supply the fluid 41 to be discharged into the pressure chamber 42. Suppose you are.

  Here, the processing operation in the ink jet head having the above configuration will be described. In the ink jet head, when a required voltage is applied between the substrate side electrode 33 and the diaphragm side electrode 35 in the microfluidic drive unit 30, an electrostatic attractive force is generated between the electrodes as shown in FIG. Thus, the diaphragm 31 integrated with the diaphragm side electrode 35 is bent toward the substrate side electrode 33. On the other hand, when the voltage application between the substrate side electrode 33 and the diaphragm side electrode 35 is released, the diaphragm 31 is released from the electrostatic attractive force as shown in FIG. Damping vibration. Due to the volume fluctuation of the pressure chamber 42 in the fluid supply unit 40 due to the vertical vibration of the vibration plate 31, in the ink jet head, the fluid 41 to be discharged in the pressure chamber 42 is discharged from the nozzle 44 to the outside and into the pressure chamber 42. The discharged fluid 41 is supplied through the fluid supply path.

  At this time, when the vibration plate 31 bends toward the substrate side electrode 33, the hollow structure portion 35 is a closed space, so that the air in the hollow structure portion 35 is compressed and attempts to inhibit the deformation of the vibration plate 31. To do. However, if the vibration plate 31 is a support structure by the support column 36, the auxiliary support column 39, etc., the compressed air can be released into the hollow structure portion 35 below the adjacent vibration plate 31, resulting in sufficient vibration plate. 31 can be bent.

  Next, a method for manufacturing the ink jet head having the above configuration will be described. 10-12 is explanatory drawing which shows the outline | summary of the manufacturing method of an inkjet head.

  In manufacturing the ink jet head, particularly in manufacturing the microfluidic drive unit 30 and the fluid supply unit 40, first, a substrate 51 is prepared as shown in FIG. As already described, the substrate 51 may be a substrate in which an insulating film 51b made of a silicon oxide film or the like is formed on a silicon substrate 51a, for example.

Then, as shown in FIG. 10B, for example, an impurity-doped polysilicon film 52 to be the substrate-side electrode 33 is selectively formed on the substrate 51, and an insulating film 53 is further formed on the surface thereof. The insulating film 53 is a protective film for the substrate-side electrode 33 and is formed of a film that is resistant to sacrificial layer etching described later. Specifically, for example, when the sacrificial layer etching uses an etching gas such as SF ₆ , CF ₄ , or XeF _2, it is formed of a silicon oxide film, and when an etching gas of hydrofluoric acid is used, it is formed of a silicon nitride film. Good.

  After that, as shown in FIG. 10C, the sacrificial layer 54 is selectively formed in the region where the microfluidic drive unit 30 by the electrostatic MEMS element is to be formed, except for the support portion by the support column 36 and the auxiliary support column 39. Form. The film type of the sacrificial layer 54 is determined by the etchant. As described above, the interval between the support columns 36 is preferably 2 μm or more and 10 μm or less, and most preferably about 5 μm.

  Then, as shown in FIGS. 10D to 10F, on the sacrificial layer 54, for example, a silicon oxide film 55, which is an insulating film, and a diaphragm-side electrode 35, for example, having a film thickness of about 300 nm. A polysilicon film 56, a silicon oxide film 57 having a film thickness of about 70 nm, which is an insulating film, a silicon nitride film 58 having a film thickness of about 300 nm by, for example, low pressure CVD (film formation temperature is 700 ° C. to 900 ° C.) having a tensile stress, and A silicon oxide film 59 having a thickness of about 70 nm, for example, formed by CVD, which becomes an insulating protective film, is sequentially formed and laminated. The silicon oxide film 59 can be omitted. It is also conceivable that the polysilicon film 56 is subjected to ion implantation of a predetermined impurity after the film formation and annealed to lower its resistance value and then patterned. Further, phosphorus-doped amorphous silicon may be used in place of the polysilicon film 56, and it is also conceivable to form a silicon nitride film 58 and a silicon oxide film 59 thereafter.

  The laminated film in which the films 55 to 59 are laminated in this way is then selectively so that a portion corresponding to the side wall of the fluid supply path is exposed (opened) as shown in FIGS. The opening 61 is formed by patterning. The opening 61 is for selectively removing the sacrificial layer 54 by sacrificial layer etching.

Here, the formation of the opening 61 will be described in detail. In forming the opening 61, first, isotropic etching is performed as shown in FIG. At this time, since the angle of the mouth of the opening 61 is determined, the isotropic etching is performed shallowly. Then, as shown in FIG. 11B, the opening 61 is dug down by RIE using a gas such as CF ₄ or C ₄ F ₈ . Thereby, the opening 61 has a tapered inclined surface of approximately 45 °. Thereafter, the opening 61 is further dug down until the opening 61 can be sealed, and the sacrificial layer 54 having a thickness of about 100 nm, which is a gap height that does not hinder sacrificial layer etching, remains. Over-etching is performed on the sacrificial layer 54.

  After the opening 61 is formed in this way, then, as shown in FIG. 11C, a silicon oxide film 62 as a sidewall protective layer of the opening 61 is formed by CVD with a film thickness of about 100 nm. Then, as shown in FIG. 11D, the tapered inclined surface is used again by using the exposure mask used when patterning the opening 61 or by using an exposure mask different from the exposure mask. A hole 63 having a diameter of about 0.5 μm is formed by patterning on the bottom of the opening 61 formed in a mortar shape. The hole 63 can be filled with about φ10 μm, but it is desirable that the hole 63 is about φ0.5 μm in consideration of the interval between the columns 36 and the like.

  In each step shown in FIGS. 11A to 11D, it is conceivable that a contact hole with an electrode for connection to the outside is formed at the same time as the opening 61 is formed. Then, in order to form an electrode for connection to the outside, metal sputtering and patterning are performed. At this time, Al is optimal for metal sputtering.

After that, as shown in FIG. 11E, sacrificial layer etching is performed using the opening 61 and the hole 63 formed in the opening 61 to selectively remove the sacrificial layer 54. When the sacrificial layer 54 is made of a polysilicon film, a gas such as XeF ₂ , SF ₆ , or CF ₄ may be used for the etchant. When the insulating films 53 and 55 are made of a silicon nitride film and the sacrificial layer 54 is made of a silicon oxide film, a hydrofluoric acid solution may be used as an etchant. By removing the sacrificial layer 54, the microfluidic drive unit 30 having an electrostatic MEMS structure including the substrate side electrode 33, the hollow structure portion 34, the diaphragm side electrode 35, and the diaphragm 31 is formed. It is.

  However, the opening 61 and the hole 63 are not sealed only by performing the sacrifice layer etching. Therefore, after the sacrificial layer etching, as shown in FIG. 12A, the opening 61 and the hole 63 that are still open are sealed by metal sputtering. In this case, aluminum is suitable for the sputtering material. In addition, a film thickness of 1 μm or less is sufficient at this time. Then, patterning is performed on the film formation result by metal sputtering, and only the opening 61 is left and removed. As a result, the sealing film 64 is formed in the portion of the opening 61. The hollow structure portion 34 is vacuum sealed. Thereby, the so-called crosstalk and squeezed dump effect due to the movement of air in the hollow structure portion 34 can be ignored.

  Thereafter, in order to prevent intrusion of outside air, fluid, and the like from the interface between the sealing film 64 and the silicon oxide film of the outermost layer of the microfluidic drive unit 30, as shown in FIG. The resulting plasma silicon nitride film 65 is laminated with a film thickness of, for example, 30 nm or more. The cover layer may be a plasma oxide film.

  After the microfluidic drive unit 30 is configured in this way, thereafter, as shown in FIG. 12C, a thick film negative resist 66 that forms the partition wall 43a constituting the fluid supply unit 40 is formed to a height of 50 μm or more. Further, as shown in FIG. 12 (d), a nozzle sheet 67 having nozzles 67a is adhered thereon. As a result, the fluid supply unit 40 is formed on the microfluidic drive unit 30, and as a result, an ink jet head including the microfluidic drive unit 30 and the fluid supply unit 40 is configured. The partition wall 43a may be formed by, for example, patterning glass by etching or sand blasting and bonding. Moreover, it is also possible to form the partition wall 43a and the nozzle sheet 67 by integral molding, for example with resin.

  According to the ink jet head configured as described above and the ink jet printer apparatus using the ink jet head, the functional element having the hollow structure portion 35, that is, the functional element that vibrates the diaphragm 31 by electrostatic attraction is used. Therefore, the ink 41 that is a micro fluid can be accurately controlled and ejected. Furthermore, since it is formed by the thin film formation technique as described above, it is very easy to cope with high density while ensuring the driving force for the ink 41. Therefore, it is possible to increase the number of pixels without increasing power consumption and without reducing ejection performance, so that it can sufficiently meet the need for high-quality printing at high speed. Become.

  In addition, in the ink jet head and the ink jet printer apparatus described above, the openings 37 and 61 for forming the hollow structure portion 35 are formed in a taper shape, so that the voids are prevented from being generated and the openings 37 and 61 are reliably sealed. It becomes possible to do. Furthermore, if a protective layer is laminated on the tapered inclined surfaces of the openings 37 and 61 and overetching is performed on the sacrificial layer, it is more preferable for ensuring the sealing of the openings 37 and 61. It will be something. Even when applied to an ink jet head that handles ink 41, which is a microfluidic, these things ensure that the ink 41 penetrates into a location where the ink 41 should not enter, particularly in the hollow structure portion 35. Since it can be prevented, it becomes very effective.

In the present embodiment, an ink jet head has been described as an example of a representative fluid ejection head, but the present invention is not limited to this. As fluid ejection heads, in addition to inkjet heads, for example, polymer or low molecular organic material coating devices such as organic EL, printed circuit board wiring printing devices, solder bump printing devices, three-dimensional modeling devices, μTAS (Micro Total Analysis Systems) Examples include supply heads that control and supply chemical liquids and other liquids in minute units of pl (picoliters) or less, and supply heads that control and supply gases in minute amounts with high precision. It is possible to apply the present invention in exactly the same way.
The same applies to the printing apparatus. That is, the printing apparatus according to the present invention is not limited to the ink jet printer apparatus as long as it uses a fluid ejection head.
Further, the same applies to the functional elements constituting the fluid ejection head, and the present invention can be applied to any functional element having a hollow structure. As such functional elements, in addition to those constituting the fluid ejection head, for example, MEMS, semiconductor elements, resonators, vibrator frequency filters, FBARs, SAW filters, gyro sensors, liquid crystal elements, organic electroluminescent elements, resistors Element, relay element, LED, laser element, light source element such as FED, speaker element, diaphragm type sensor (for example, microphone, pressure sensor), flow path, tube, imaging element, optical switch, other various sensors and relays, etc. The present invention can be easily applied to any of these, and in that case, it contributes to miniaturization, cost reduction, high performance, and the like. In addition, for these functional elements, there are a hollow structure part that is completely sealed and a part that is partially open, but the present invention can be applied to any of these functional elements. is there.

Further, in the present embodiment, the case where the hollow structure portion 35 is formed by sacrificial layer etching and the openings 37 and 61 for this purpose are tapered has been described as an example. However, the hollow structure portion is not necessarily limited to that formed by sacrificial layer etching. For example, a functional element is formed on a silicon substrate, and the functional element is formed or a protective film of the functional element is opened. It is also possible to form a hollow structure portion in the silicon substrate by etching the silicon substrate through the tapered hole and then seal the tapered hole.
For this reason, the present invention may be applied to an opening for forming a fluid supply path, for example. That is, as shown in FIG. 13, like the hollow structure portion 35, the fluid supply path 71 also has a sacrificial layer or a part 71 of the silicon substrate 71 by etching from the slit-like groove 72 that reaches the sacrificial layer or the silicon substrate. If the groove 72 used for the removal is sealed after the removal of the substrate, the groove 72 can be formed into a taper shape so that reliable sealing is possible. Matching is not required, and a flow path that can prevent fluid leakage at low cost can be formed. The fluid supply path formed in this way supplies the fluid 41 to the fluid supply path of the ink jet head, which is a typical example of the fluid discharge head, specifically to the fluid supply unit 40 shown in FIG. Therefore, it can be used as a fluid supply path.

  That is, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

It is explanatory drawing which shows an example of schematic structure of the functional element which concerns on this invention. It is explanatory drawing which shows the specific example of the relationship between sealing and gap height in opening. It is explanatory drawing (the 1) which shows the outline | summary of the manufacturing method of the functional element which concerns on this invention. It is explanatory drawing (the 2) which shows the outline | summary of the manufacturing method of the functional element which concerns on this invention. It is explanatory drawing which shows the outline | summary of an inkjet printer apparatus. It is a perspective view showing typically an example of the principal part composition of the fluid discharge head concerning the present invention. It is a top view which shows typically an example of a principal part structure of the fluid discharge head which concerns on this invention. It is a sectional side view showing typically an example of the principal part composition of the fluid discharge head concerning the present invention. It is explanatory drawing which shows typically the outline | summary of the processing operation in the fluid discharge head which concerns on this invention. It is explanatory drawing (the 1) which shows the outline | summary of the manufacturing method of the fluid discharge head which concerns on this invention. It is explanatory drawing (the 2) which shows the outline | summary of the manufacturing method of the fluid discharge head which concerns on this invention. It is explanatory drawing (the 3) which shows the outline | summary of the manufacturing method of the fluid discharge head which concerns on this invention. It is explanatory drawing which shows an example of schematic structure of the functional element which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Functional element, 2 ... Hollow structure part, 3 ... Opening, 4 ... Etching-resistant layer, 5 ... Sealing film, 6 ... Cover layer, 7 ... Protective layer, 8 ... Over-etching part, 11 ... Semiconductor silicon substrate, 12 ... polysilicon film, 13 ... silicon nitride film, 14, 16 ... resist film, 15 ... silicon oxide film, 17 ... sealing film, 21 ... paper, 22 ... roller, 23 ... carriage, 24,25 ... inkjet head, 30 DESCRIPTION OF SYMBOLS ... Micro fluid drive part, 31 ... Diaphragm, 32 ... Substrate, 33 Substrate side electrode, 34 ... Hollow structure part, 35 ... Diaphragm side electrode, 36 ... Post, 37 ... Opening, 38 ... Sealing film, 39 ... Auxiliary Column (post), 40 ... Fluid supply unit, 41 ... Ink, 42 ... Pressure chamber (cavity), 43 ... Partition structure, 43a ... Partition, 44 ... Discharge unit (nozzle), 51 ... Substrate, 52 ... Polysilicon film, 53. Insulating film, 5 ... sacrificial layer, 55 ... silicon oxide film, 56 ... polysilicon film, 57 ... silicon oxide film, 58 ... silicon nitride film, 59 ... silicon oxide film, 61 ... opening, 62 ... silicon oxide film, 63 ... hole, 64 ... Sealing film, 65 ... plasma silicon nitride film, 66 ... thick film negative resist, 67 ... nozzle sheet, 67a ... nozzle, 71 ... fluid supply path, 72 ... opening

Claims (24)

In the functional element having a hollow structure portion formed by sealing the opening,
The cross-sectional shape of the opening is formed in a tapered shape in which the diameter of the opening becomes narrower toward the hollow structure portion ,
A protective layer is laminated at least on the tapered inclined surface portion in the opening ,
A sealing film is laminated on the protective layer of the tapered inclined surface and the region of the opening, and the sealing film is formed on the surface of the hollow structure portion that faces the opening from the opening. A functional element that is partially sealed . The protective layer functional device according to claim 1, wherein the protective layer of the single layer or multiple layers in a portion of the tapered inclined surfaces prior Symbol opening and wherein the stacked. The protective layer is also laminated on an over-etched portion with respect to the sacrificial layer when the hollow structure portion is formed by removing the sacrificial layer from the opening. The functional element described. The functional element according to claim 1, wherein the opening is sealed with a sealing film made of any one of a deposited film, a sputtered film, and a PECVD film. The functional element according to claim 4, wherein the sealing film is covered with a single-layer or multi-layer cover layer. The functional element according to claim 5, wherein the cover layer is a plasma silicon nitride film. In the method for manufacturing a functional element having a hollow structure portion formed by sealing the opening,
Forming a cross-sectional shape of the opening into a tapered shape in which the diameter of the opening becomes narrower toward the hollow structure portion ;
Laminating a protective layer on at least the tapered inclined surface in the opening ;
The hollow structure portion is formed by forming a sealing film in a region of the protective layer of the tapered inclined surface and the opening, and laminating the sealing film on the surface of the hollow structure portion facing the opening from the opening. And a step of sealing a part of the functional element. The method for manufacturing a functional element according to claim 7, wherein the step of laminating the protective layer includes a step of laminating a single layer or a multi-layer protective layer at least on a portion of the tapered inclined surface in the opening. In the case where the hollow structure portion is formed by removing the sacrificial layer from the opening, in the step of forming the tapered shape prior to the step of laminating the protective layer, the sacrificial layer is overcoated. Etching is performed. The manufacturing method of the functional element of Claim 8 characterized by the above-mentioned. The method for manufacturing a functional element according to claim 7, wherein the opening is sealed with a sealing film made of any one of a deposited film, a sputtered film, and a PECVD film. The method for manufacturing a functional element according to claim 10, wherein the sealing film is covered with a single-layer or multi-layer cover layer. The method for manufacturing a functional element according to claim 11, wherein the cover layer is a plasma silicon nitride film. In a fluid discharge head configured using a functional element having a hollow structure portion formed by sealing an opening,
The cross-sectional shape of the opening is formed in a tapered shape in which the diameter of the opening becomes narrower toward the hollow structure portion ,
A protective layer is laminated on at least the tapered inclined surface in the opening ,
The hollow structure is formed by forming a sealing film in a region of the opening and the protective layer of the tapered inclined surface, and laminating the sealing film on the surface of the hollow structure portion facing the opening from the opening. A fluid discharge head, wherein a part of the portion is sealed . 14. The fluid discharge head according to claim 13, wherein a protective layer having a single layer or a plurality of layers is laminated at least on a portion of the tapered inclined surface in the opening. When the hollow structure portion is formed by removing the sacrificial layer from the opening, the protective layer is also laminated on an over-etched portion with respect to the sacrificial layer. The fluid discharge head described. The fluid discharge head according to claim 13, wherein the opening is sealed with a sealing film made of any one of a vapor deposition film, a sputtered film, and a PECVD film. The fluid ejection head according to claim 16, wherein the sealing film is covered with a single layer or a multilayer cover layer. The fluid discharge head according to claim 17, wherein the cover layer is a plasma silicon nitride film. In a printing apparatus configured using a functional element having a hollow structure portion formed by sealing an opening as a fluid discharge head,
The cross-sectional shape of the opening is formed in a tapered shape in which the diameter of the opening becomes narrower toward the hollow structure portion ,
A protective layer is laminated on at least the tapered inclined surface in the opening ,
The hollow structure is formed by forming a sealing film in a region of the opening and the protective layer of the tapered inclined surface, and laminating the sealing film on the surface of the hollow structure portion facing the opening from the opening. A printing apparatus, wherein a part of the part is sealed . The printing apparatus according to claim 19, wherein a protective layer is laminated at least on a portion of the tapered inclined surface in the opening. 21. When the hollow structure portion is formed by removing a sacrificial layer from the opening, the protective layer is also laminated on an over-etched portion with respect to the sacrificial layer. The printing apparatus as described. The printing apparatus according to claim 19, wherein the opening is sealed with a sealing film made of any one of a vapor deposition film, a sputtered film, and a PECVD film. The printing apparatus according to claim 22, wherein the sealing film is covered with a single-layer or multi-layer cover layer. The printing apparatus according to claim 23, wherein the cover layer is a plasma silicon nitride film.

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