JP2007190730A - Mask substrate, its manufacturing method, liquid droplet ejection head, and method for manufacturing liquid droplet ejection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for manufacturing a mask substrate enhancing a freedom degree of a design, a mask obtained by the method, a liquid ejection head manufactured by the mask, and a method for manufacturing a liquid droplet ejection device. <P>SOLUTION: The mask substrate 1 using silicon as a material for protecting a portion other than a working portion of the substrate to be worked is equipped with a contact surface side opening portion 2 formed into a shape, corresponding to the shape of the working portion by anisotropic dry etching, on the surface side in contact with the substrate to be worked, and with an outside opening portion 3 in which a wall surface is formed with the silicone remained along a specified crystal face orientation by anisotropic wet etching from a surface side opposite to the surface in contact with the substrate to be worked and a through-hole communicating with the contact surface side opening portion is formed. <P>COPYRIGHT: (C)2007,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 microelements and 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 various fields regardless of whether it is for home 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 a droplet is 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. are also used in the manufacture of

  In the droplet discharge head, a discharge chamber for storing 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 deforming (being operated) and discharging the droplets 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). Although there is a mask formed by film formation, a mask substrate (hereinafter referred to as a mask substrate) is used here.

JP 2005-349687 A

  At this time, with respect to a mask for performing processing with higher accuracy, for example, a substrate made of silicon that can be applied with MEMS and can perform high-accuracy opening, and has little change such as expansion due to heat during processing. It is considered desirable to use

  However, when manufacturing a mask substrate, it is usually performed by an anisotropic wet etching method (hereinafter referred to as wet etching), and wet etching depends on the crystal plane orientation. For this reason, when manufacturing a mask substrate, for example, the thickness of the mask substrate for obtaining a predetermined opening width is limited, the degree of freedom in design becomes low. In addition, it is necessary to determine the interval (pitch) between the openings in consideration of the crystal orientation.

  Therefore, in order to solve such problems, the present invention provides a mask substrate manufacturing method capable of increasing the degree of design freedom, a mask obtained by the method, a droplet discharge head manufactured by the mask, a liquid It aims at obtaining the manufacturing method of 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 is subjected to anisotropic dry etching on a surface side in contact with the substrate to be processed. It is left along the predetermined crystal plane orientation by anisotropic wet etching from the contact side opening formed in the shape corresponding to the shape of the processed part and the surface opposite to the surface in contact with the substrate to be processed. A wall surface is formed by the silicon, and an external opening that communicates to form a through hole.
According to the present invention, the contact surface side opening is formed by anisotropic dry etching so as to correspond to the shape corresponding to the shape of the processed portion without restriction of the crystal plane, so that highly accurate processing by an arbitrary shape can be performed. It can be carried out. Since the outer side opening is formed from the outer surface side by wet etching, the manufacturing time can be reduced.

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

In addition, the mask substrate according to the present invention further includes a counterbore portion formed of a concave portion for preventing contact with a predetermined portion other than the processed portion on the surface side in contact with the substrate to be processed.
According to the present invention, since the counterbore portion is further provided, it is possible to prevent the predetermined portion of the substrate to be processed from coming into contact with the mask substrate. .

Further, the counterbore part of the mask substrate according to the present invention is formed in a larger range than the predetermined part so as to cover the predetermined part to be protected on the object to be processed.
According to the present invention, since the counterbore part is provided so as to cover the predetermined part, the predetermined part can be reliably protected.

Further, the mask substrate manufacturing method according to the present invention performs anisotropic dry etching from one surface of the single crystal silicon substrate, and at least the peripheral portion of the contact surface side opening on the surface side in contact with the substrate to be processed. A step of forming, an anisotropic wet etching is performed from the side opposite to the one side to form an outer surface side opening, and a through hole is formed by the contact surface side opening and the outer surface side opening. Have
According to the present invention, the contact surface side opening is formed by anisotropic dry etching so as to correspond to the shape corresponding to the shape of the processed part without restriction of the crystal surface, and the contact surface side opening is arbitrarily The opening shape can be formed with high accuracy, and the opening on the outer surface side is formed by performing anisotropic wet etching, so that the time can be shortened. In addition, a high-quality mask substrate can be easily manufactured using a simple method using patterning by photolithography, wet etching, and dry etching.

In the mask substrate manufacturing method according to the present invention, anisotropic wet etching is performed using an aqueous potassium hydroxide solution and / or an aqueous tetramethylammonium hydroxide solution.
According to the present invention, a potassium hydroxide aqueous solution and / or a tetramethylammonium hydroxide aqueous solution is used for anisotropic wet etching, so that a mask substrate with little variation in etching and uniform dimensional accuracy in the planar direction is obtained. Can be manufactured.

In addition, the mask substrate manufacturing method according to the present invention forms, on one surface side of the silicon substrate, a concave portion that becomes a counterbore portion so as not to be in contact with a predetermined portion to be processed independently of the contact surface side opening.
According to the present invention, for example, the counterbore part is formed in the same process as the formation of the contact surface side opening part or in another process. Therefore, the predetermined part of the substrate to be processed is not brought into contact with the mask substrate. For example, the loss of a predetermined part can be prevented by, for example, the insertion of a foreign substance.

In addition, the method for manufacturing 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 to be 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.

The manufacturing method of the droplet discharge device according to the present invention applies the above-described manufacturing method of the droplet discharge head to manufacture the droplet discharge device.
According to the present invention, since the above-described mask substrate is used, it is possible to manufacture a droplet discharge device with high processing accuracy, good discharge performance, durability, and the like.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a part of a mask cross section according to the first embodiment of the present invention. 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 counterbore (counterbore) portion 4. Here, the contact surface side opening portion 2 and the counterbore portion 4 are formed by a method (hereinafter referred to as dry etching) by anisotropic dry etching (dry etching by plasma discharge), and the external opening portion 3 is wet etched (liquid is removed). It is formed by a method (hereinafter referred to as wet etching) using wet etching.

  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 counterbore 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 recessed 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. For example, although it depends on the size of the foreign matter, the thickness of the mask substrate 1, etc., it is desirable that the depth is at least 10 μm, more preferably several tens of μm (20 to 30 μm). Here, it is assumed that the contact surface side opening 2 (outer surface side opening 3) and the counterbore 4 are provided independently (not communicated). Here, if the counterbore part 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. 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. 2A). ). 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.

  In order to perform patterning by selectively etching the silicon oxide film 12, a photolithography method is used to apply a photosensitive agent that becomes a resist film, and by exposure and development, a portion that becomes the contact surface side opening 2 and a counterbore are formed. The resist film in the portion that becomes the portion 4 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 The portions of the silicon oxide film 12 that become the portions and the portions that become the counterbore portions 4 are removed by etching. (FIG. 2 (b)). Here, although silicon in the portion that becomes the contact surface side opening 2 is exposed, in etching performed later, the contact surface side opening 2 and the counterbore portion 4 are made to have different etching depths, and the counterbore portion 4 is made to contact the surface. In order to make it shallower than the side opening 2, the silicon oxide film in the portion that becomes the counterbore 4 is left thin, and half etching is performed without exposing the silicon. Further, when the area of the opening portion to be formed is large with respect to the contact surface side opening portion 2, only the boundary portion (peripheral portion: outer frame) between the opening portion and the wall surface of the contact surface side opening portion 2 is exposed and dried. If etching is performed, since the wet etching is performed in the subsequent process and the central portion is removed when the substrate penetrates, it is convenient for shortening the etching time. Here, the portion to be the counterbore 4 is formed in a wider range than the effective pattern.

  Next, dry etching is performed, and the exposed silicon is etched by a predetermined depth (FIG. 2C). 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 becomes deeper, 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 narrowed. Therefore, it tends to be deeper when the interval between the processed parts is narrow. 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 frame (such as the width of the opening) of the contact surface side opening 2 can be defined regardless of the thickness of the silicon substrate 11.

  When dry etching is completed, the silicon oxide film 12 formed as a protective film is removed (FIG. 2D). Then, a silicon oxide film 13 is formed on the entire surface as a protective film for further wet etching (FIG. 2E). 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. After the silicon oxide film 13 is formed, the silicon oxide film 13 is exposed by wet etching to remove the portion that becomes the outer surface side opening 3 in the silicon oxide film 13 (FIG. 2F).

  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. 2G). 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, have little variation in etching, and have a good dimensional accuracy with respect to the plane. 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.

  Then, the silicon oxide film 13 formed as a protective film is removed to complete the mask (FIG. 2 (h)). 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, according to the first embodiment, since the opening shape of the portion that becomes the contact surface side opening 2 is formed by dry etching, the etching shape is limited by the crystal plane orientation in dry etching. Therefore, the degree of freedom of the shape of the opening portion can be increased, and the mask substrate 1 having the contact surface side opening portion 2 of the shape designed thereby can perform processing of the processing target in an arbitrary shape. Can do. On the other hand, since the outer surface side opening 3 is formed by dry etching, a plurality of substrates can be processed at one time, and the time during manufacturing can be reduced. Further, since the counterbore part 4 is provided, the mask substrate 1 does not come into contact with the effective pattern formed on the surface of the processing target, and the effective pattern can be protected and the processing target can be prevented from being lost. In particular, if the counterbore part 4 is formed so as to cover the effective pattern, more reliable protection can be performed. When the mask substrate 1 is manufactured, a high-quality mask substrate can be easily manufactured by using a simple method using patterning by photolithography, wet etching, and dry etching.
In addition, since an aqueous potassium hydroxide solution and / or an aqueous tetramethylammonium hydroxide solution is used for anisotropic wet etching, a mask substrate with less variation in etching and more uniform in the planar direction can be obtained.

Embodiment 2. FIG.
FIG. 3 is an exploded view of the droplet discharge head according to Embodiment 2 of the present invention. FIG. 3 shows a part of the droplet discharge head. 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 21 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 21 (particularly at the bottom) so as to face each discharge chamber 31 (vibrating plate 32) of the cavity substrate 20, and further, a lead portion 23 and a terminal portion 24 are provided. They are provided integrally (hereinafter, these are collectively described as electrodes 22a unless otherwise required). Between the diaphragm 32 and the electrode 22a (particularly the individual electrode 22), a certain gap (gap) that allows the diaphragm 32 to bend (displace) is formed by the recess 21. The electrode 22a is formed by depositing ITO (Indium Tin Oxide) with a thickness of 0.1 μm inside the recess 21 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). On the cavity substrate 30, a recess (the bottom wall is a diaphragm 32 serving as a movable electrode) serving as the discharge chamber 31 and a sealing material 35 are deposited immediately above the lead portion 23 and sealed as described later. A through-slot hole 36 for forming the portion 36a is formed. The narrower the through-groove hole 36 contributes to the miniaturization, but here it is 10 μm to 20 μm in order to deposit the sealing material 35 well. 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 film (here, Tetraethyl orthosilicate Tetraethoxysilane: tetraethoxysilane) for electrically insulating the diaphragm 32 and the individual electrodes 22 is formed on the lower surface of the cavity substrate 30 (the surface facing the electrode substrate 20). An insulating film 33 (which is an SiO ₂ film made of ethyl silicate) 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 serving as the liquid inlet 25 (communication with the through-hole provided in the electrode substrate 20). 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 electrode 22a (particularly the individual electrode 22) from an external power supply means (not shown) to the substrate (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 (which communicates with a through-hole provided in the electrode substrate 20) is also provided on the bottom surface of the recess as a liquid intake 25. 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 for each nozzle (each discharge chamber 31).

  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 diagram illustrating a top view and a cross-sectional view of the droplet discharge head. FIG. 4 is a view of the droplet discharge head as viewed from above with the cavity substrate 30 as the center (FIG. 4A), and a diagram showing a cross section taken along the dashed line AA ′ (FIG. 4B). is there. In order to expose each terminal portion 24 of the electrode substrate 20 bonded to the cavity substrate 30, a part of the cavity substrate 30 is opened to form a space between the electrode substrate 20 and the cavity substrate 30 (this space is defined as Hereinafter, it is referred to as an electrode outlet 34). The driver IC 60 serving as power (charge) supply means for the electrodes 22a (particularly the individual electrodes 22) is electrically connected to the terminal portions 24 at the electrode outlets 34, and supplies charges to the selected individual electrodes 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 is attracted to the individual electrode 22 to bend. 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.

  Here, in the present embodiment, a through-groove hole 36 for exposing the lead portion 23 is provided in the cavity substrate 30. Here, the narrower the width in the longitudinal direction of the through-slot hole 36, the more the size can be reduced. 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, from the opening portion of the through-hole 36, the lead portion 23 portion of the electrode substrate 20 reaches the cavity substrate 30 by a method such as CVD (Chemical Vapor Deposition), (ECR) sputtering, or vacuum deposition. Silicon oxide (SiO ₂ ), which is a sealing material 35, is deposited in a space (a part of the gap) to form a sealing portion 36a, and the gap is blocked from outside air to prevent entry of moisture, foreign matter, and the like. 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.

  5 and 6 are views showing a manufacturing process of the droplet discharge head according to the first embodiment. The droplet discharge head manufacturing process will be described with reference to FIGS. Actually, a plurality of droplet discharge head members are simultaneously formed for each wafer, but only a part thereof is shown in FIGS.

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 (to be 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, whereby boron is diffused into the silicon substrate 61 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 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 an aqueous hydrofluoric acid solution in a state of being chemically changed to B ₂ O ₃ + SiO ₂ (FIG. 5A).

On the surface on which the boron doped layer 72 is formed, the 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 / min ( The insulating film 33 is formed to a thickness of 0.1 μm under the conditions of 100 sccm) and an oxygen flow rate of 1000 cm ³ / min (1000 sccm) (FIG. 5B).

  The electrode substrate 20 is manufactured in a separate process from the above-described FIGS. 5 (a) and 5 (b). A recess 21 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 21, an electrode 22 a having a thickness of 0.1 μm is 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. 5C). ).

  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 the 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 w%. As a result, the thickness of the silicon substrate 71 is reduced to about 50 μm (FIG. 5D).

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. 5E). 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 forming the TEOS hard mask 73, resist patterning is performed in order to etch the TEOS hard mask 73 in the portions that will become the discharge chamber 31, the through groove 36, and the electrode outlet 34. Then, the TEOS hard mask 73 is patterned by etching the portions until the TEOS hard mask 73 disappears using a hydrofluoric acid aqueous solution, and the silicon substrate 71 is exposed at those portions. After the etching, the resist is peeled off (FIG. 5F).

  Next, the bonded substrate is dipped in a 35 wt% potassium hydroxide aqueous solution, and anisotropic wet etching (hereinafter referred to as “etching”) is performed until the thickness of the portion that becomes the discharge chamber 32, the through groove 36, and the electrode outlet 34 is about 10 μm. , Referred to as wet etching). 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. 6 (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.

FIG. 7 is a diagram showing the relationship between the silicon substrate 71 and the mask substrate 1. When the wet etching is completed, 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 portion that becomes the through groove hole 36 and the electrode extraction port 34, the mask substrate 1 manufactured in Embodiment 1 in which the portion that becomes the through groove hole 36 and the electrode extraction port 34 is opened. Is attached to the surface of the bonded substrate on the silicon substrate 71 side. Then, for example, RIE dry etching (anisotropic dry etching) is performed for 30 minutes under the conditions of an RF power of 200 W, a pressure of 40 Pa (0.3 Torr), and a CF ₄ flow rate of 30 cm ³ / min (30 sccm). Plasma is applied only to the portion that becomes the electrode outlet 34 to open (FIG. 6 (h)). Here, for example, in order to increase the alignment accuracy between the bonded substrate and the silicon mask, the mask substrate 1 may be mounted by pin alignment in which pins are passed between the bonded substrate and the mask substrate 1. A protective film is formed on the surface of the mask substrate 1 so that the mask substrate 1 itself is not etched.

  Further, the mask substrate 1A opened in accordance with the through-groove hole 36 is attached to the surface of the bonded substrate on the silicon substrate 71 side. Also in this step, it is preferable to carry out by pin alignment. Here, in consideration of alignment accuracy and the like, the opening portion of the silicon mask is made to be closer to the opening portion of the through-slot hole 36 so that the sealing material 35 does not adhere to the surface of the cavity substrate 30 (the bonding surface with the reservoir substrate 40). It is desirable to keep it small. Then, for example, the sealing material 35 is deposited in the through groove hole 36 by plasma CVD using TEOS, vapor deposition, sputtering, or the like to form the sealing portion 36a (FIG. 6 (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.

  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. 6J).

  The reservoir substrate 40 prepared in a separate process is bonded and bonded from the cavity substrate 30 side of the bonded substrate with, for example, an epoxy adhesive. In addition, the driver IC 60 is connected to the terminal unit 24. Further, the nozzle substrate 40 manufactured in a separate process is similarly bonded from the bonded reservoir substrate 30 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. 6 (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 cavity substrate is formed by the contact surface side opening 2 formed in an arbitrary shape. High-precision processing can be performed at 30 predetermined positions. Further, the counterbore part 4 can protect the concave part to be the discharge chamber 31 of the cavity substrate 30 and the mask substrate 1 without making contact with each other, and maintain the quality without causing a defect due to the mounting of the mask substrate. 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. 8 is an external view of a droplet discharge apparatus (printer 100) using the droplet discharge head manufactured in the above embodiment. FIG. 9 is a diagram illustrating an example of main components of the droplet discharge device. 8 and 9 is intended for printing by a droplet discharge method (inkjet method). Further, it is a so-called serial type device. In FIG. 9, a drum 101 that supports a printing paper 110 that is a substrate to be printed and a droplet discharge head 102 that discharges ink to the printing 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 4, 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 is 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.

It is a figure showing a part of mask cross section which concerns on Embodiment 1 of this invention. It is a figure showing the manufacturing process of the mask in this Embodiment. 2 is an exploded view of a droplet discharge head according to Embodiment 1. FIG. It is sectional drawing of a droplet discharge head. FIG. 6 is a diagram illustrating a manufacturing process (No. 1) of the droplet discharge head according to the first embodiment. FIG. 6 is a diagram illustrating a manufacturing process (No. 2) of the droplet discharge head according to the first embodiment. It is a figure showing the relationship between the silicon substrate 71 and the mask substrate 1. FIG. It is an external view of a droplet discharge device using a droplet discharge head. It is a figure showing an example of the main structural means of a droplet discharge apparatus.

Explanation of symbols

1, 1A, 1B mask substrate, 2 contact surface side opening, 3 outer surface side opening, 4 counterbore, 11 silicon substrate, 12, 13 silicon oxide film, 20 electrode substrate, 21 recess, 22 individual electrode, 22a electrode, 23 Lead portion, 24 Terminal portion, 25 Liquid intake port, 30 Cavity substrate, 31 Discharge chamber, 32 Vibration plate, 33 Insulating film, 34 Electrode outlet port, 35 Sealing material, 36 Through groove, 36a Sealing portion, 37 Common electrode terminal, 40 reservoir substrate, 41 reservoir, 42 supply port, 43 nozzle communication 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, 103 Paper pressure roller, 104 Feed screw, 105 Belt, 106 Motor, 107 Lint control means, 110 print paper.

Claims (9)

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 on the surface side 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 from the surface side opposite to the surface in contact with the substrate to be processed, and communicated with the opening on the contact surface side. A mask substrate comprising an external opening for forming a through hole.   2. The mask substrate according to claim 1, wherein the surface is made of single crystal silicon having a (100) plane orientation, and the wall surface of the external opening is formed leaving the (111) plane orientation.   3. The mask substrate according to claim 1, further comprising a counterbore portion formed of a concave portion for preventing contact with a predetermined portion other than the processed portion on a surface side in contact with the substrate to be processed.   The counterbore part is formed in a larger range than the predetermined part so as to cover the predetermined part to be protected on the object to be processed. Mask substrate. Patterning one surface of the single crystal silicon substrate and performing anisotropic dry etching to form at least a peripheral portion of the contact surface side opening on the surface side in contact with the substrate to be processed;
Patterning is performed on the surface opposite to the one surface, anisotropic wet etching is performed to form an outer surface side opening, and a through hole is formed by the contact surface side opening and the outer surface side opening. A process for producing a mask substrate, comprising:   6. The method of manufacturing a mask substrate according to claim 5, wherein the anisotropic wet etching is performed using a potassium hydroxide aqueous solution and / or a tetramethylammonium hydroxide aqueous solution.   7. The concave portion that is a counterbore part that is independent of the opening on the contact surface side and is not brought into contact with the predetermined part to be processed is formed on one surface side of the silicon substrate. Manufacturing method of the mask substrate.   A method for manufacturing a droplet discharge head, comprising at least a step of processing a substrate on which a flow path of a liquid to be discharged from a nozzle is formed using the mask substrate according to claim 1. 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 8.

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