JP2009119699A - Mask substrate, its manufacturing method, liquid droplet ejection head, and manufacturing method of liquid droplet ejection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mask substrate and its manufacturing method which can control a surface defect caused by the contact of the surface to be worked, suppress the deformation of the mask substrate, form a micro pattern with high precision, and make productivity excellent. <P>SOLUTION: The mask substrate 1 is formed of silicon for protecting parts other than the worked part of the substrate. The surface side touching the substrate to be worked has a contact surface side orifice 2 which is formed in a configuration corresponded to a worked part configuration by an anisotropy dry etching, and a recess 4 which is formed independently of the contact surface side orifice and formed so as not to contact with the predetermined parts other than the worked part. In the surface side opposite to the surface contacting the substrate to be worked, a wall surface is formed of the silicon which is left behind along a predetermined crystal face bearing by anisotropy wet etching, and an exterior surface side orifice 3 communicating with the contact surface side orifice is for, and the sidewall thickness a of the contact surface side orifice 2 is made thicker than the depth b of the recess 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a mask for protecting a portion other than a predetermined portion when manufacturing a microfabricated element, and a mask obtained thereby. The present invention also relates to a method for manufacturing a droplet discharge head and a droplet discharge device manufactured using the mask substrate.

  For example, micro electro mechanical systems (MEMS) that process silicon or the like to form minute elements or the like have made rapid progress. Examples of microfabricated elements formed by microfabrication technology include, for example, a droplet discharge head (inkjet head), a micropump, and an optical variable filter used in a recording (printing) apparatus such as a droplet discharge type printer. There are electrostatic actuators such as motors, pressure sensors and the like.

  Here, a droplet discharge head that is an electrostatic actuator will be described as an example of a microfabricated element. A droplet discharge type recording (printing) apparatus is used for printing in all fields regardless of household use or industrial use. The droplet discharge method is, for example, a method in which a droplet discharge head having a plurality of nozzles is moved relative to an object (paper, etc.), and droplets are discharged to a predetermined position of the object for printing or the like. It is. This method uses a color filter for manufacturing a display device using liquid crystal, a display panel using an electroluminescence element such as an organic compound (OLED), a microarray of biomolecules such as DNA and protein, etc. Etc. are also used in the manufacture of

  In the droplet discharge head, a discharge chamber for storing a liquid is provided in a part of the flow path, and at least one wall of the discharge chamber (here, referred to as a bottom wall, hereinafter referred to as a diaphragm) There is a method in which the pressure in the discharge chamber is increased by changing the shape by bending (being operated), and droplets are discharged from the communicating nozzle. As a force for displacing the diaphragm that becomes the movable electrode, for example, an electrostatic force (often using an electrostatic attractive force) generated between the electrode (fixed electrode) facing the diaphragm at a distance is used. ing. When forming an electrostatic actuator using the electrostatic force as described above, a mask for protecting a portion other than the portion to be processed is used in processing in various processes such as etching (for example, Patent Documents). 1, see Patent Document 2). Although there is a mask formed by film formation, a mask substrate (hereinafter referred to as a mask substrate) is used here.

JP 2002-305079 A JP 2007-190730 A

  However, as shown in Patent Document 1, when a thin film pattern is formed using a mask made of silicon, the portion other than the opening is in direct contact with the surface of the substrate to be processed. In such a case, there is a problem that contact damage from the mask is received and surface defects remain on the substrate to be processed.

  On the other hand, in the mask shown in Patent Document 2, on the surface side in contact with the substrate to be processed, the contact surface side opening and the processed portion other than the processed portion (the processed effective pattern is formed by anisotropic dry etching). A concave portion for protecting the outer surface side, and an outer surface side opening portion comprising a tapered through hole communicating with the contact surface side opening portion by anisotropic wet etching is provided on the outer surface side. Since the protective film patterning on the surface side where the wet etching is performed is performed only once, a portion opened by the anisotropic wet etching (opening portion on the contact surface side) and the concave portion have to have the same etching depth. Therefore, as the area of the recess increases, the in-plane etching rate decreases, and when deep digging, a problem arises that the processing time becomes longer and the productivity becomes lower. Conversely, if the depth of anisotropic dry etching is reduced, the time required for anisotropic wet etching at the outer surface side opening becomes longer, and the side wall thickness of the contact surface side opening (here, so-called For example, when a substrate to be processed is processed by a sputtering method, there arises a problem that the flange is deflected by the stress of the sputtered film and the amount of spattering increases.

  In view of such a problem, the present invention makes it possible to suppress surface defects due to contact with the surface to be processed, suppress deformation of the mask substrate, process a fine pattern with high accuracy, and improve productivity. It is an object of the present invention to obtain a good mask substrate manufacturing method, and further to obtain a mask obtained by the method, a droplet discharge head manufactured using the mask, and a method of manufacturing a droplet discharge device.

  A mask substrate according to the present invention is a mask substrate made of silicon for protecting a portion other than a processed portion of a substrate to be processed, and anisotropic dry etching is performed on a side in contact with the substrate to be processed. The contact surface side opening formed in a shape corresponding to the shape of the processing portion, and the recess formed independently from the contact surface side opening and not in contact with a predetermined portion other than the processing portion A wall surface is formed by silicon left along a predetermined crystal plane orientation by anisotropic wet etching on the surface side opposite to the surface in contact with the substrate to be processed. The outer surface side opening part which communicates is provided, and the side wall thickness of the contact surface side opening part is formed thicker than the depth of the recess.

  According to the present invention, since the side wall thickness of the contact surface side opening is formed to be thicker than the depth of the recess, deformation such as warpage of the contact surface side opening can be suppressed, so that wraparound of processing materials such as sputtering is suppressed. Can be performed with high accuracy. Further, since the concave portion covers the effective pattern so as not to be in contact with the portion other than the processed portion, that is, the effective pattern, surface defects due to contact such as foreign object pinching can be suppressed.

The mask substrate according to the present invention is formed using single crystal silicon whose surface is a (100) orientation and the wall surface of the opening on the outer surface is left with the (111) orientation.
According to the present invention, since the surface of the (100) orientation single crystal silicon is used as a material and the wall surface of the outer surface side opening portion is left (111), it can be formed into a tapered shape, for example, a material to be deposited Etc. can easily enter the opening.

The concave portion of the mask substrate according to the present invention is formed in a range larger than a predetermined portion.
Therefore, the effective pattern can be protected more reliably.

  The mask substrate manufacturing method according to the present invention includes a first step of patterning at least a peripheral portion of a portion serving as a contact surface side opening on a surface side in contact with a substrate to be processed on one surface of a single crystal silicon substrate. A second step of patterning a concave portion for preventing contact with a predetermined portion other than a processed portion of the substrate to be processed on one surface of the single crystal silicon substrate; and a protective film after the first step. Removing the silicon by etching to expose the silicon, after the second step, a step of thinning the protective film by etching so as not to expose the silicon, and a portion to be the contact surface side opening where the silicon is exposed Etching to a predetermined depth by anisotropic dry etching to form a contact surface side opening, and removing the thinned protective film by anisotropic dry etching to form a recess Etching the part to a predetermined depth by anisotropic dry etching, forming a recess, patterning on the side opposite to one side, performing anisotropic wet etching, and opening on the outer side And forming the contact surface side opening and the outer surface side opening in communication with each other.

According to the present invention, since the patterning of the portion serving as the contact surface side opening and the patterning of the portion serving as the recess are performed separately at least twice, the side wall thickness of the contact surface side opening is set to the depth of the recess. It can be formed thicker. Further, since the depth of the concave portion may be the minimum necessary depth, the etching time can be shortened and the productivity of the mask substrate is improved.
Further, since at least the peripheral portion of the portion that becomes the contact surface side opening is patterned, the contact surface side opening is formed in a form in which the central portion falls off. Therefore, the anisotropic dry etching time can be shortened, and the productivity is improved.

The mask substrate manufacturing method according to the present invention performs anisotropic wet etching using an aqueous potassium hydroxide solution or an aqueous tetramethylammonium hydroxide solution.
According to the present invention, since an aqueous potassium hydroxide solution or an aqueous tetramethylammonium hydroxide solution is used for anisotropic wet etching, a mask substrate with little variation in etching and high dimensional accuracy in the planar direction is manufactured. be able to.

In the mask substrate manufacturing method according to the present invention, it is desirable to perform patterning in independent layers so that the first and second steps have different protective film thicknesses.
According to the present invention, it is possible to set the contact surface side opening and the recess independently at an arbitrary etching depth, and process the relationship between the side wall thickness of the contact surface side opening and the depth of the recess. It can be optimally adjusted according to the target.

A manufacturing method of a droplet discharge head according to the present invention includes at least a step of processing a substrate on which a flow path of liquid discharged from a nozzle is formed using the mask substrate.
According to the present invention, since the above-described mask substrate is used, it is possible to manufacture a droplet discharge head that can perform high-precision processing in a predetermined shape at a predetermined position.

Embodiment 1 FIG.
FIG. 1A is a view showing a part of a mask cross section according to the first embodiment of the present invention, and FIG. 1B is a plan view thereof.
This embodiment is composed of a mask substrate 1 and is formed by etching a silicon substrate (note that components are illustrated in the following drawings including FIG. May be different from the actual relationship, and the upper side of the figure is the upper side and the lower side is the lower side). Although not particularly limited, in this embodiment mode, a single crystal silicon substrate having a (100) plane orientation is used as the silicon substrate. The mask substrate 1 has a contact surface side opening 2, an outer surface side opening 3, and a recess 4. Here, the contact surface side opening 2 and the recess 4 are formed by a method by anisotropic dry etching (dry etching by plasma discharge) (hereinafter referred to as dry etching), and the outer surface side opening 3 is wet etched (liquid is removed). It is formed by a method (hereinafter referred to as wet etching) using wet etching. And the side wall thickness a of the contact surface side opening part 2 is formed thicker than the depth b of the recessed part 4 (a> b). In addition, there is no restriction | limiting in particular about the number of the contact surface side opening part 2, the outer surface side opening part 3, and the recessed part 4. FIG.

  The contact surface side opening 2 and the outer surface side opening 3 communicate with each other, and both surfaces of the mask substrate 1 pass therethrough. The shape of the contact surface side opening 2 is formed in accordance with the shape of the processed portion of the substrate to be processed. The recess 4 protects the mask substrate 1 without contacting any predetermined portion (hereinafter referred to as an effective pattern) formed on the surface of the processing target to be processed using the mask substrate 1. It is a cover part provided in the contact surface side. This is because, for example, when a foreign object (for example, a particle) that cannot be completely cleaned is present on the surface of the processing target when the substrate to be processed is cleaned, the foreign object is sandwiched by contact with the mask substrate 1 and an effective pattern is formed. This is to prevent damage. The recess 4 has a depth of at least 10 μm, more preferably several tens of μm (20 to 30 μm), depending on, for example, the size of foreign matter and the thickness of the mask substrate 1. Here, it is assumed that the contact surface side opening 2 (outer surface side opening 3) and the recess 4 are provided independently (not communicated). Here, if the recess 4 is formed larger than the effective pattern, more reliable protection can be achieved.

  FIG. 2 is a diagram showing a mask manufacturing process in the present embodiment. Next, a mask manufacturing method will be described.

(A) First, a silicon oxide film 12 serving as a film (resist) for protecting the silicon substrate 11 when etching is performed on the silicon substrate 11 having a desired thickness, for example, about 1.2 μm (FIG. 2). (A)). The film formation method is not particularly limited, but here, a method by thermal oxidation in which the silicon substrate 11 is exposed to an oxygen and water vapor atmosphere at a high temperature (about 1075 ° C.) is used.

(B) Next, in order to perform patterning by selectively etching the silicon oxide film 12, a photosensitizing agent is applied using a photolithography method, and exposure and development are performed to form the contact surface side opening 2. The resist film in the part to be removed is removed. Then, for example, immersed in a hydrofluoric acid aqueous solution, a buffered hydrofluoric acid aqueous solution (BHF: for example, a liquid in which a hydrofluoric acid aqueous solution and an ammonium fluoride aqueous solution are mixed at 1: 6), a diluted hydrofluoric acid aqueous solution, or the like, the contact surface side opening 2 Then, the silicon oxide film 12 in the portion 2a is removed by etching (FIG. 2B). Here, when the area of the opening portion to be formed is large for the contact surface side opening portion 2, only the boundary portion (peripheral portion) between the opening portion and the wall surface of the contact surface side opening portion 2 is exposed, and dry etching is performed. By doing so, when the substrate is penetrated through wet etching in the subsequent process, the central portion is also removed, which is convenient for shortening the etching time.

(C) Next, a second patterning is performed on the portion 4a to be the concave portion 4 by using a photolithography method (FIG. 2C). That is, in the first patterning of (b), the silicon in the portion 2a that becomes the contact surface side opening 2 is exposed, but in this second patterning, the contact surface side opening 2 and the recess are formed in the etching performed later. In order to make the depth of etching 4 different from that of the recess 4 and to make the depth of the recess 4 shallower than the opening 2 on the contact surface side, the silicon oxide film 12 of the portion 4a that becomes the recess 4 is left thin, and the half does not expose silicon. Etching is performed. Here, the portion 4a to be the recess 4 is formed in a wider range than the effective pattern.

(D) Next, the silicon oxide film 12 in the portion 4a to be the recess 4 is removed by dry etching to expose the silicon (FIG. 2D). In addition, the portion 2 a that becomes the contact surface side opening 2 is etched deeper than the portion 4 a that becomes the recess 4. Here, the type of dry etching is not particularly limited, but in this embodiment, for example, dry etching using ICP (Inductively Coupled Plasma) discharge or the like is performed. In the case of dry etching, since it is not restricted by the crystal plane orientation, for example, the wall surface can be formed in a direction perpendicular to the substrate. Therefore, the width and the like of the contact surface side opening 2 can be defined regardless of the thickness of the silicon substrate 11.

(E) Subsequently, dry etching is performed to etch the contact surface side opening 2 and the concave portion 4 by a predetermined depth (FIG. 2E). Here, the etching depth is not particularly limited because it varies depending on the width of the silicon substrate 11, the range of wet etching to be performed later, and the like, and may be any depth. Here, for example, as the depth of dry etching increases, wet etching from the outer surface side opening 3 becomes shallower, and the opening width of the surface of the silicon substrate 11 having the outer surface side opening 3 can be reduced. Therefore, when the distance between the outer surface side openings 3 is narrow, the depth of dry etching tends to be deep.

(F) When dry etching is completed, the silicon oxide film 12 formed as a protective film is removed (FIG. 2F).
(G) Then, a silicon oxide film 13 is formed on the entire surface as a protective film for further wet etching (FIG. 2G). There is no particular limitation on the method for forming the film, but here, a thermal oxidation method capable of forming a film regardless of unevenness is used.
(H) After the formation of the silicon oxide film 13, the portion 3 a that becomes the outer surface side opening 3 is patterned again by photolithography, and the silicon oxide film 13 of the portion 3 a that becomes the outer surface side opening 3 is wetted. The silicon is removed by etching (FIG. 2 (h)).

(I) Then, the substrate is immersed in an etching solution, and wet etching is performed until the contact surface side opening 2 and the outer surface side opening 3 communicate with each other (FIG. 2 (i)). Here, the liquid (etchant) used for the wet etching is not particularly limited, but in this embodiment, for example, a potassium hydroxide (KOH) aqueous solution, a 25 weight percent tetramethylammonium hydroxide (TMAH) aqueous solution (organic) Alkaline solution) shall be used. The KOH aqueous solution and the TMAH aqueous solution have a good selection ratio relationship with the silicon oxide film, there are few variations in etching, and the dimensional accuracy with respect to the plane is good. In particular, the TMAH aqueous solution is used as a developer. Here, silicon remains along the (111) crystal plane which is difficult to etch, and the wall surface of the opening is formed at an angle of about 55 ° with respect to the substrate. Thereby, since the opening portion is formed in a tapered shape, for example, a material for forming a film, a layer, or the like, gas, or the like easily enters the opening portion.

(J) Then, the silicon oxide film 13 formed as a protective film is removed to complete the mask (FIG. 2 (j)). For example, an insulating protective film for protecting the mask substrate 1 (silicon) from liquid, gas, or the like may be formed depending on the application to be used.
As described above, the side wall thickness a of the contact surface side opening 2 can be formed thicker than the depth b of the recess 4.

As described above, according to the first embodiment, the portion 2a that becomes the contact surface side opening 2 and the portion 4a that becomes the recess 4 are sequentially patterned at least twice in the front and rear directions. When the contact surface side opening 2 and the recess 4 are formed at a desired etching depth, the side wall thickness a of the contact surface side opening 2 can be made thicker than the depth b of the recess 4.
Therefore, it becomes possible to arbitrarily set the side wall thickness a of the contact surface side opening 2 without depending on the depth b of the concave portion 4, and by increasing the thickness of the flange portion of the contact surface side opening 2, Since deformation such as warpage can be suppressed, the adhesion of the mask substrate 1 to the substrate to be processed is improved. As a result, when this mask substrate 1 is used to form a desired fine pattern on the substrate to be processed, for example, by sputtering, it is possible to prevent spattering, so that highly accurate pattern formation is possible. It becomes possible.

  Also for the recess 4, the depth b of the recess 4 can be arbitrarily set, and the occurrence of contact damage in the effective pattern area due to foreign object pinching or the like can be suppressed. In addition, since the depth b of the recess 4 can be arbitrarily set, the recess 4 can have the minimum necessary depth without depending on the etching depth of the contact surface side opening 2, so that the dry etching time can be shortened. Can improve productivity.

  Further, the portion 2a to be the contact surface side opening 2 and the portion 4a to be the recess 4 may be patterned in independent layers so as to have different thicknesses of the silicon oxide films 12 and 13. In this way, by repeating the patterning a plurality of times, the contact surface side opening 2 and the recess 4 can be independently set at arbitrary etching depths, and the side wall thickness of the contact surface side opening 2 is increased. The relationship (a> b) between a and the depth b of the recess 4 can be optimally adjusted according to the object to be processed.

  Further, since the opening shape of the portion that becomes the contact surface side opening 2 is formed by dry etching, the etching shape is not limited by the crystal plane orientation in the dry etching. The degree of freedom can be increased, and the processing of a processing target having an arbitrary shape can be performed by the mask substrate 1 having the contact surface side opening 2 having a shape designed thereby. On the other hand, since the outer surface side opening 3 is formed by wet etching, a plurality of substrates can be processed at a time, and the time during manufacturing can be reduced. In addition, since an aqueous potassium hydroxide solution or an aqueous tetramethylammonium hydroxide solution is used for anisotropic wet etching, it is possible to obtain a mask substrate 1 with less variation in etching and more uniform in the planar direction.

Embodiment 2. FIG.
FIG. 3 is an exploded perspective view showing a droplet discharge head according to Embodiment 2 of the present invention. In the present embodiment, the substrate to be processed using the mask substrate 1 manufactured in the first embodiment, for example, a cavity substrate 30 of a droplet discharge head which is a device using an electrostatic actuator that is driven by an electrostatic method. The case will be described.

  As shown in FIG. 3, the droplet discharge head according to the present embodiment is configured by stacking four substrates in order from the bottom: an electrode substrate 20, a cavity substrate 30, a reservoir substrate 40, and a nozzle substrate 50. Here, in the present embodiment, the electrode substrate 20 and the cavity substrate 30 are bonded by anodic bonding. The cavity substrate 30 and the reservoir substrate 40, and the reservoir substrate 40 and the nozzle substrate 50 are bonded using an adhesive such as an epoxy resin.

The electrode substrate 20 is mainly made of a substrate such as borosilicate heat-resistant hard glass having a thickness of about 1 mm. In the present embodiment, the glass substrate is used, but single crystal silicon may be used as the substrate, for example. On the surface of the electrode substrate 20, a plurality of recesses 41 having a depth of, for example, about 0.3 μm are formed in accordance with a recess that becomes a discharge chamber 31 of the cavity substrate 30 described later. An individual electrode 22 serving as a fixed electrode is provided inside the recess 41 (particularly at the bottom) so as to face each discharge chamber 31 (vibrating plate 32) of the cavity substrate 30, and one end of the individual electrode 22 ( The end portion on the side extending to the center of the electrode substrate 20) is an IC output mounting portion 23 for mounting with the driver IC 60. Furthermore, a lead portion 24 for connection to a driver IC 60 and an FPC (Flexible Print Circuit) (not shown) is formed in the center portion of the electrode substrate 20 with an ITO (Indium Tin Oxide) pattern. The lead part 24 is composed of a plurality of leads (wirings). In the present embodiment, the lead part 24 refers to a plurality of leads connected to one driver IC 60. Further, the number and method of mounting the driver IC 60 are not particularly limited. The lead portion 24 is an FPC mounting portion 24a connected to an FPC IC input wiring (not shown) at the end portion of the electrode substrate 20, and an IC input connected to the input terminal of the driver IC 60 at two locations. The mounting parts 24b and 24c and the IC input signal wiring 24d wired under the driver IC 60 are configured. The output terminal of the driver IC 60 is connected to the individual electrode 22 in each column. Thus, since the wiring of the lead part 24 is formed in a state sandwiched between the electrode substrate 20 and the driver IC 60, it is possible to perform compact wiring without increasing the area of the droplet discharge head (increasing in the lateral direction). it can.
Between the diaphragm 32 and the individual electrode 22, a certain gap (gap) in which the diaphragm 32 can be bent (displaced) is formed by the concave portion 41. The individual electrode 22 is formed by depositing ITO with a thickness of 0.1 μm inside the recess 41 by, for example, sputtering. In addition, the electrode substrate 20 is provided with a through-hole serving as a liquid intake 25 serving as a flow path for taking in liquid supplied from an external tank (not shown).

  The cavity substrate 30 is mainly composed of a silicon single crystal substrate (hereinafter referred to as a silicon substrate). The cavity substrate 30 has a recess (the bottom wall is a vibrating plate 32 serving as a movable electrode) and a driver IC 60 serving as a discharge chamber 31 and an IC output mounting portion of each lead electrode 24 on the electrode substrate 20 and each individual electrode 22. IC mounting opening 34 composed of a through-groove hole for mounting on 23, and sealing material 35 as described later are deposited immediately above IC output mounting portion 23 to form sealing portion 35a. A sealing opening 36 made of a through groove is formed. The narrower the width of the opening 36 for sealing, the smaller the contribution, but here, in order to deposit the sealing material 35 well, the thickness is set to 10 μm to 20 μm. However, the present invention is not limited to this. Further, the deposited sealing material 35 has a thickness equal to or larger than the gap width (about 0.18 μm) even in a small portion. It is desirable that the thickness be about 2 to 3 μm or more as long as the bonding with the reservoir substrate 40 is not affected.

A TEOS (here, Tetraethylorthosilicate Tetraethoxysilane) is used on the lower surface of the cavity substrate 30 (the surface facing the electrode substrate 20) to electrically insulate between the diaphragm 32 and the individual electrodes 22. The insulating film 33, which is an SiO ₂ film made of ethyl), is formed to a thickness of 0.1 μm using a plasma CVD (Chemical Vapor Deposition: TEOS-pCVD) method. Although the insulating film 33 is a TEOS film here, for example, Al ₂ O ₃ (aluminum oxide (alumina)) may be used. Here, the cavity substrate 30 is also provided with a through hole 38 communicating with the liquid intake 25. Furthermore, a common electrode terminal 37 is provided which serves as a terminal for supplying a charge having a polarity opposite to that of the individual electrode 22 from an external power supply means (not shown) to the cavity substrate 30 (the diaphragm 32).

  The reservoir substrate 40 is mainly made of a silicon substrate, for example. The reservoir substrate 40 is formed with a recess serving as a reservoir (common liquid chamber) 41 for supplying a liquid to each discharge chamber 31. A through hole 44 that communicates with the liquid intake 25 through the through hole 38 is also provided on the bottom surface of the recess. A supply port 42 for supplying a liquid from the reservoir 41 to each discharge chamber 31 is formed in accordance with the position of each discharge chamber 31. Furthermore, a plurality of nozzle communication holes that serve as flow paths between the discharge chambers 31 and the nozzle holes 51 provided in the nozzle substrate 50 and serve as flow paths for transferring the liquid pressurized in the discharge chambers 31 to the nozzle holes 51. 43 is provided according to each nozzle hole 51 (each discharge chamber 31). A through-groove 45 having substantially the same shape is formed in the central portion of the reservoir substrate 40 so as to correspond to the IC mounting opening 34.

  For the nozzle substrate 50, for example, a silicon substrate is used as a main material. A plurality of nozzle holes 51 are formed in the nozzle substrate 50. Each nozzle hole 51 discharges the liquid transferred from each nozzle communication hole 43 to the outside as a droplet. If the nozzle holes 51 are formed in a plurality of stages, an improvement in straightness when discharging droplets can be expected. In the present embodiment, the nozzle holes 51 are formed in two stages. Here, a diaphragm for buffering the pressure applied to the liquid on the reservoir 41 side by the diaphragm 32 may be provided.

  FIG. 4 is a partial cross-sectional view of the droplet discharge head showing the assembled state. However, it is a cross-sectional view of one row of nozzle holes 51. In order to mount the driver IC 60 on the IC output mounting portion 23 that is the terminal portion of each individual electrode 22 of the electrode substrate 20 bonded to the cavity substrate 30, the electrode substrate 20 and the cavity substrate are opened by opening a part of the cavity substrate 30. 30 to form a space (hereinafter, this space is referred to as an IC mounting opening 34). The driver IC 60 serving as power (charge) supply means for the individual electrode 22 is electrically connected to the lead portion 24 and the IC output mounting portion 23 of each individual electrode 22 in the IC mounting opening 34, and the selected individual electrode is selected. A charge is supplied to 22.

  A voltage of about 40 V is applied to the individual electrode 22 selected by the driver IC 60 and is positively charged. At this time, the diaphragm 32 is relatively negatively charged (here, charge having a negative polarity is supplied to the cavity substrate 30 via the common electrode terminal 37 such as FPC (Flexible Print Circuit)). Therefore, an electrostatic force is generated between the selected individual electrode 22 and the diaphragm 32, and the diaphragm 32 is attracted to the individual electrode 22 and bent. As a result, the volume of the discharge chamber 31 increases. When the charge supply is stopped, the vibration plate 32 returns to the original state, but the volume of the discharge chamber 31 at that time also returns to the original state, and the liquid pressurized by the pressure is discharged from the nozzle hole 51 as a droplet. Printing or the like is performed when the droplets land on a recording sheet, for example.

FIG. 5 is an external view of the mask substrate 1 used for simultaneously processing the IC mounting opening 34 and the sealing opening 36 in the cavity substrate 30, and FIG. 6 is a cross-sectional view showing the usage state.
As shown in FIGS. 5 and 6, in the present embodiment, an IC mounting opening 34 for mounting the driver IC 60 on the electrode substrate 20, the individual electrode 22 and the diaphragm 32 constituting the electrostatic actuator, The opening 36 for sealing for sealing the open end part of the gap between them with the sealing material 35 is processed into the cavity substrate 30 simultaneously. Therefore, the mask substrate 1 includes a contact surface side opening 2A formed in a shape corresponding to the contour shape of the IC mounting opening 34 for processing the IC mounting opening 34, and a sealing opening. The contact surface side opening 2B formed in a shape corresponding to the contour shape of the sealing opening 36 for processing the portion 36, and the concave portion that becomes the effective pattern, that is, the discharge chamber 31 formed in the cavity substrate 30. A recess 4 that covers an area slightly wider than the effective pattern so as to protect the whole, and outer surface side openings 3A, 3B in which tapered through holes communicating with the respective contact surface side openings 2A, 2B are formed; Is provided. Furthermore, the side wall thickness of the contact surface side openings 2A and 2B is formed to be thicker than the depth of the recess 4.

  The sealing opening 36 is formed as an elongated slot so that the gap between the individual electrode 22 and the diaphragm 32 on one side can be sealed at a time. The smaller the width in the short side direction, the smaller the opening. Can contribute. However, since the sealing material 35 may not be deposited well if the width is too narrow, it is preferably 10 μm to 20 μm. In some cases, the thickness of the cavity substrate 30 may be limited during processing, and thus is not particularly limited to 10 μm to 20 μm. If reliable sealing is possible, the width may be 300 μm (0.3 mm), for example. Further, as the sealing material 35 to be deposited, here, silicon oxide (inorganic compound) having high insulation and hermetic sealing ability and having resistance to acidic and alkaline solutions used for cleaning and the like is used. The deposited sealing material 35 has a thickness equal to or larger than the gap width (about 0.18 μm) even in a small portion, for example. It is desirable that the thickness be about 2 to 3 μm or more as long as the bonding with the reservoir substrate 40 is not affected.

Then, IC output mounting of the individual electrodes 22 on the electrode substrate 20 is performed from the opening portion of the sealing opening 36 by a method such as CVD (Chemical Vapor Deposition), (ECR) sputtering, or vacuum deposition. In a space (part of the gap) from the portion 23 portion to the cavity substrate 30, silicon oxide (SiO ₂ ) as the sealing material 35 is deposited to form a sealing portion 35a, and the gap is blocked from outside air, Prevent intrusion of moisture and foreign matter. Here, the sealing material 35 is not limited to silicon oxide. For example, Al ₂ O ₃ (aluminum oxide (alumina)), silicon nitride (SiN), silicon oxynitride (SiON), Ta ₂ O ₅ (tantalum pentoxide), It may be DLC (Diamond Like Carbon), polypalaxylylene, PDMS (polydimethylsiloxane: a kind of silicone rubber), epoxy resin or the like. Moreover, you may make it laminate | stack not only one type but multiple types of sealing materials.

  Next, a method for manufacturing the droplet discharge head according to the first embodiment will be described with reference to FIGS. 7 and 8 are diagrams showing a manufacturing process of the droplet discharge head. Actually, a plurality of droplet discharge head members are simultaneously formed for each wafer, but only a part thereof is shown in FIGS.

(A) One side of the silicon substrate 71 (becomes the bonding surface side with the electrode substrate 20) is mirror-polished to produce, for example, a 220 μm thick substrate (becomes the cavity substrate 30). Next, the surface on which the boron doped layer 72 of the silicon substrate 71 is formed is set on a quartz boat so as to face a solid diffusion source mainly composed of B ₂ O ₃ . Further, a quartz boat is set in a vertical furnace, the inside of the furnace is put into a nitrogen atmosphere, the temperature is raised to 1050 ° C. and held for 7 hours, so that boron is diffused into the silicon substrate 71 and a boron doped layer 72 is formed. . A boron compound (SiB ₆ : 6 boron silicide) is formed on the surface of the boron doped layer 72 taken out (not shown), but when oxidized in an oxygen and water vapor atmosphere at 600 ° C. for 1 hour and 30 minutes. Further, it can be chemically changed to B ₂ O ₃ + SiO ₂ which can be etched with a hydrofluoric acid aqueous solution. B ₂ O ₃ + SiO ₂ is removed by etching with a hydrofluoric acid aqueous solution in a state where it is chemically changed to B ₂ O ₃ + SiO ₂ (FIG. 7A).

(B) On the surface on which the boron-doped layer 72 is formed, a plasma CVD method is used, the processing temperature during film formation is 360 ° C., the high-frequency output is 250 W, the pressure is 66.7 Pa (0.5 Torr), and the gas flow rate is TEOS flow rate 100 cm ^3. The insulating film 33 is formed to a thickness of 0.1 μm under the conditions of / min (100 sccm) and an oxygen flow rate of 1000 cm ³ / min (1000 sccm) (FIG. 7B).

(C) The electrode substrate 20 is fabricated in a separate process from the above-described FIGS. 7 (a) and (b). A recess 41 having a depth of about 0.3 μm is formed on one surface of a glass substrate of about 1 mm. After the formation of the recess 41, the individual electrodes 22 having a thickness of 0.1 μm are simultaneously formed by using, for example, a sputtering method. Finally, a hole to be the liquid intake port 25 is formed by a sandblast method or a cutting process. Thereby, the electrode substrate 20 is produced. Then, after heating the silicon substrate 71 and the electrode substrate 20 to 360 ° C., a negative electrode is connected to the electrode substrate 20 and a positive electrode is connected to the silicon substrate 71, and a voltage of 800 V is applied to perform anodic bonding (FIG. 7C). ).

(D) The surface of the silicon substrate 71 is ground until the thickness of the silicon substrate 71 reaches about 60 μm with respect to the bonded substrate after anodic bonding. Thereafter, in order to remove the work-affected layer, the silicon substrate 71 is subjected to about 10 μm anisotropic wet etching (hereinafter referred to as wet etching) with a potassium hydroxide solution having a concentration of 32 wt%. As a result, the thickness of the silicon substrate 71 is reduced to about 50 μm (FIG. 7D).

(E) Next, a silicon oxide hard mask (hereinafter referred to as TEOS hard mask) 73 by TEOS is formed on the wet-etched surface by plasma CVD. As film formation conditions, for example, the processing temperature during film formation is 360 ° C., the high-frequency output is 700 W, the pressure is 33.3 Pa (0.25 Torr), the gas flow rate is TEOS flow rate 100 cm ³ / min (100 sccm), and the oxygen flow rate is 1000 cm. ^A film having a thickness of 1.5 μm is formed under the condition of ³ / min (1000 sccm) (FIG. 7E). Film formation using TEOS can be performed at a relatively low temperature, which is advantageous in that heating of the substrate can be suppressed as much as possible.

(F) After the TEOS hard mask 73 is formed, resist patterning is performed in order to etch the TEOS hard mask 73 in the portions that become the discharge chamber 31, the IC mounting opening 34, and the sealing opening 36. Then, these portions are etched using a hydrofluoric acid solution until the TEOS hard mask 73 disappears, and the TEOS hard mask 73 is patterned to expose silicon in those portions. After the etching, the resist is peeled off (FIG. 7F).

(G) Next, the bonded substrate is immersed in a 35 wt% potassium hydroxide aqueous solution, and the thickness of the portion that becomes the discharge chamber 31, the sealing opening 36, and the IC mounting sealing opening 34 is about 10 μm. Anisotropic wet etching (hereinafter referred to as wet etching) is performed until Further, the wet-etching is continued until it is determined that the bonded substrate is dipped in a 3 wt% potassium hydroxide aqueous solution, the boron-doped layer 72 is exposed, and the etching stop at which the progress of etching is extremely slow has been effective (see FIG. 8 (g)). In this way, by performing etching using two types of potassium hydroxide aqueous solutions having different concentrations, the surface roughness of the diaphragm 32 formed in the portion serving as the discharge chamber 31 is suppressed, and the thickness accuracy is 0.80 ±. It can be 0.05 μm or less. As a result, the discharge performance of the droplet discharge head can be stabilized.

(H) When wet etching is finished, the bonded substrate is immersed in a hydrofluoric acid aqueous solution, and the TEOS hard mask 73 on the surface of the silicon substrate 71 is peeled off. Next, in order to remove the boron-doped layer 72 in the portions to be the IC mounting opening 34 and the sealing opening 36, as shown in FIGS. 5 and 6, the IC mounting opening 34 and the sealing opening The mask substrate 1 manufactured in the first embodiment in which the portion that becomes the portion 36 is opened is attached to the surface of the silicon substrate 71 of the bonded substrate. Then, for example, RIE dry etching (anisotropic dry etching) is performed for 30 minutes under the conditions of RF power 200 W, pressure 40 Pa (0.3 Torr), CF ₄ flow rate 30 cm ³ / min (30 sccm), and an IC mounting opening 34, plasma is applied only to the portion that becomes the sealing opening 36 to open the opening (FIG. 8H). Here, for example, in order to improve the alignment accuracy between the bonded substrate and the mask substrate 1, the mask substrate 1 may be mounted by pin alignment in which pins are passed between the bonded substrate and the mask substrate 1. Further, the side wall thickness of the positioning hole (not shown) for pin alignment can be formed to be equal to or greater than the side wall thickness of the contact surface side openings 2A and 2B, so that the positioning pin guide property is good. Thus, the alignment accuracy is improved. A protective film is formed on the surface of the mask substrate 1 so that the mask substrate 1 itself is not etched.

(I) Furthermore, the mask substrate 1A opened in accordance with the sealing opening 36 is attached to the surface of the bonded substrate on the silicon substrate 71 side. Also in this step, the mask substrate 1A may be mounted by pin alignment. Here, in consideration of the alignment accuracy and the like, the opening portion of the mask substrate 1 </ b> A is formed on the sealing opening portion 36 so that the sealing material 35 does not adhere to the surface of the cavity substrate 30 (bonding surface with the reservoir substrate 40). It is desirable to make it smaller than the opening. Then, for example, the sealing material 35 is deposited on the sealing opening 36 by plasma CVD using TEOS, vapor deposition, sputtering, or the like to form the sealing portion 35a (FIG. 8 (i)). The thickness of the sealing material 35 to be deposited is not particularly limited as described above. However, since the gap width is about 0.2 μm, the thinnest portion has a thickness of about 2 to 3 μm or more. It suffices if it can be deposited in a range that does not affect the bonding of the film.

(J) When the sealing is completed, for example, the mask substrate 1B having an opening that becomes the common electrode terminal 37 is attached to the surface of the bonded substrate on the silicon substrate 71 side by, for example, pin alignment. Then, for example, sputtering is performed using platinum (Pt) as a target to form the common electrode terminal 37 (FIG. 8J).

(K) The reservoir substrate 40 prepared in a separate process in advance is bonded and bonded from the cavity substrate 30 side of the bonded substrate, for example, with an epoxy adhesive. In addition, the driver IC 60 is connected to the IC output mounting portion 23 and the lead portion 24 of the individual electrode 22. Further, the nozzle substrate 50 manufactured in a separate process is similarly bonded from the bonded reservoir substrate 40 side with, for example, an epoxy adhesive. Then, dicing is performed along the dicing line, and individual droplet discharge heads are cut to complete the droplet discharge heads (FIG. 8 (k)).

  As described above, according to the second embodiment, since the mask substrate 1 of the first embodiment is used in manufacturing the droplet discharge head, the contact surface side openings 2A and 2B formed in an arbitrary shape High-precision processing can be performed on a predetermined position of the cavity substrate 30. Further, the concave portion 4 can protect the concave portion serving as the discharge chamber 31 of the cavity substrate 30 without contacting the mask substrate 1, and maintain quality without causing defects due to the mounting of the mask substrate 1. Can do. As described above, it is possible to obtain a liquid droplet ejection head with high processing accuracy and excellent ejection performance and durability.

Embodiment 3 FIG.
In the above-described embodiment, the droplet discharge head configured by stacking the four substrates of the electrode substrate 20, the cavity substrate 30, the reservoir substrate 40, and the nozzle substrate 50 has been described, but the present invention is not limited to this. For example, the present invention can also be applied to a droplet discharge head configured with a three-layer substrate in which the discharge chamber and the reservoir are formed on the same substrate. For example, in such a case, a mask substrate that matches the shape of the substrate is manufactured.

Embodiment 4 FIG.
FIG. 9 is an external view of a droplet discharge apparatus (printer 100) using the droplet discharge head manufactured in the above embodiment. FIG. 10 is a diagram showing an example of main constituent means of the droplet discharge device. 9 and 10 is intended for printing by a droplet discharge method (inkjet method). Further, it is a so-called serial type device. In FIG. 10, a drum 101 that supports a print paper 110 that is a substrate to be printed and a droplet discharge head 102 that discharges ink to the print paper 110 and performs recording are mainly configured. Although not shown, there is an ink supply means for supplying ink to the droplet discharge head 102. The print paper 110 is held by being pressed against the drum 101 by a paper press roller 103 provided parallel to the axial direction of the drum 101. A feed screw 104 is provided parallel to the axial direction of the drum 101, and the droplet discharge head 102 is held. As the feed screw 104 rotates, the droplet discharge head 102 moves in the axial direction of the drum 101.

  On the other hand, the drum 101 is rotationally driven by a motor 106 via a belt 105 or the like. Further, the print control unit 107 drives the feed screw 104 and the motor 106 based on the print data and the control signal, and although not shown here, drives the oscillation drive circuit to vibrate the diaphragm 32, Printing is performed on the print paper 110 while controlling.

  Here, the liquid is ejected onto the print paper 110 as ink, but the liquid ejected from the droplet ejection head is not limited to ink. For example, in an application to be discharged onto a substrate to be a color filter, a light emitting element is used in an application to be discharged onto a substrate of a display panel (OLED or the like) using an electroluminescent element such as a liquid containing a color filter pigment or an organic compound. For example, a liquid containing a conductive metal and a liquid containing a conductive metal may be discharged from a droplet discharge head provided in each device. In addition, when the droplet discharge head is used as a dispenser and used for discharging onto a substrate that is a microarray of biomolecules, DNA (Deoxyribo Nucleic Acids: deoxyribonucleic acid), other nucleic acids (for example, Ribo Nucleic Acid: ribonucleic acid, Peptide (Nucleic Acids: peptide nucleic acids, etc.) A liquid containing a probe such as a protein may be discharged. In addition, it can also be used for discharging dyes such as cloth.

Embodiment 5 FIG.
In the above-described second embodiment, the manufacturing of the droplet discharge head has been described as an example. However, an element that can use the mask substrate of the first embodiment is not limited to this. For example, the above-described mask substrate is also used for sensors, such as motors, sensors, vibrating elements (resonators) such as SAW filters, tunable optical filters, mirror devices, and other types of microfabricated actuators, pressure sensors, etc. Can be processed. It can also be applied to elements such as semiconductors.

(A) is a figure showing a part of mask cross section which concerns on Embodiment 1 of this invention, (b) is a top view. The figure showing the manufacturing process of the mask in this Embodiment. FIG. 4 is an exploded view of a droplet discharge head according to a second embodiment. FIG. 3 is a partial cross-sectional view of a droplet discharge head. FIG. 6 is an external view of a mask substrate used in Embodiment 2. The figure showing the use condition of a mask board | substrate. FIG. 6 is a diagram illustrating a manufacturing process (part 1) of the droplet discharge head according to the second embodiment. FIG. 6 illustrates a manufacturing process (No. 2) of the droplet discharge head according to the second embodiment. FIG. 3 is an external view of a droplet discharge device using a droplet discharge head. The figure showing an example of the main structural means of a droplet discharge apparatus.

Explanation of symbols

  1, 1A, 1B mask substrate, 2, 2A, 2B contact surface side opening, 3, 3A, 3B outer surface side opening, 4 recess, 11 silicon substrate, 12, 13 silicon oxide film, 20 electrode substrate, 21 recess, 22 Individual electrode, 23 IC output mounting part, 24 Lead part, 25 Liquid inlet, 30 Cavity substrate, 31 Discharge chamber, 32 Vibration plate, 33 Insulating film, 34 IC mounting opening, 35 Sealing material, 35a Sealing 36, opening for sealing, 37 common electrode terminal, 40 reservoir substrate, 41 reservoir, 42 supply port, 43 nozzle communication hole, 44 through hole, 45 through groove hole, 50 nozzle substrate, 51 nozzle hole, 60 driver IC 71 silicon substrate, 72 boron doped layer, 73 TEOS hard mask, 100 printer, 101 drum, 102 droplet discharge head, 03 paper pressure roller, 104 a feed screw, 105 belt, 106 motor, 107 print control means 110 print paper.

Claims (8)

A mask substrate made of silicon for protecting a portion other than a processed portion of a substrate to be processed,
A contact surface side opening formed in a shape corresponding to the shape of the processed portion by anisotropic dry etching is provided on the surface side in contact with the substrate to be processed, and the contact surface side opening is provided independently. A recess formed so as not to contact a predetermined part other than the processed part,
On the surface opposite to the surface in contact with the substrate to be processed, a wall surface is formed by silicon left along a predetermined crystal plane orientation by anisotropic wet etching, and communicates with the opening on the contact surface side. With an opening on the outer surface,
A mask substrate, wherein a side wall thickness of the contact surface side opening is formed thicker than a depth of the recess.   2. The mask substrate according to claim 1, wherein the surface is made of single crystal silicon having a (100) orientation, and the wall surface of the opening on the outer surface side is formed with the (111) orientation remaining.   The mask substrate according to claim 1, wherein the recess is formed in a range larger than the predetermined portion. A first step of patterning at least a peripheral portion of a portion serving as a contact surface side opening on a surface side in contact with the substrate to be processed on one surface of the single crystal silicon substrate;
A second step of patterning, on one surface of the single crystal silicon substrate, a portion to be a recess for preventing contact with a predetermined portion other than a processed portion of the substrate to be processed;
After the first step, removing the protective film by etching to expose the silicon;
After the second step, the step of thinning the protective film by etching so as not to expose the silicon,
Etching the portion that becomes the contact surface side opening where the silicon is exposed to a predetermined depth by anisotropic dry etching to form the contact surface side opening;
Removing the thinned protective film by anisotropic dry etching and then etching the portion to be the recess to a predetermined depth by anisotropic dry etching to form the recess; and
Patterning the surface opposite to the one surface, performing anisotropic wet etching, forming an outer surface side opening, and communicating the contact surface side opening and the outer surface side opening;
A method for manufacturing a mask substrate, comprising:   5. The method of manufacturing a mask substrate according to claim 4, wherein the anisotropic wet etching is performed using an aqueous potassium hydroxide solution or an aqueous tetramethylammonium hydroxide solution.   6. The method of manufacturing a mask substrate according to claim 4, wherein in the first step and the second step, patterning is performed in an independent layer so as to have different protective film thicknesses.   The flow path of the liquid discharged from a nozzle is formed using the mask substrate according to any one of claims 1 to 3 or the mask substrate manufactured by the mask substrate manufacturing method according to any one of claims 4 to 6. A method for manufacturing a droplet discharge head, comprising at least a step of processing a substrate to be processed.   A method for manufacturing a droplet discharge device, wherein the droplet discharge device is manufactured by applying the method for manufacturing a droplet discharge head according to claim 7.

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