JPH07125210A - Thermal ink jet head - Google Patents

Abstract

PURPOSE:To improve a method for forming the passage grooves, common liquid chamber region and ink inflow orifices of a passage substrate in a head structure wherein a heating element substrate having a heat generating layer and the passage substrate having passage grooves are laminated. CONSTITUTION:In relation to the passage substrate 3 laminated on a heating element substrate 2 having a heat generating layer, a plurality of parallel passage grooves 6 having a trapezoidal cross-sectional shape and a common liquid chamber region 7 are simultaneously formed by one anisotropic etching process utilizing a single crystal silicon wafer cut out as the crystal azimuth surface of a (100) surface to enhance the accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal ink jet head having a head structure in which a heating element substrate and a flow path substrate which are one of non-impact recording heads are laminated.

[0002]

2. Description of the Related Art The non-impact recording method is a recording method of great interest in that noise generation during recording is so small that it can be ignored. Among them, the so-called inkjet recording method, which enables high-speed recording and can perform recording on so-called plain paper without requiring a special fixing process, is an extremely powerful recording method. Therefore, conventionally, various methods have been proposed for the inkjet recording method, various improvements have been added, and some have been commercialized, and some have been in the development stage for practical use.

In such an ink jet recording method, recording is carried out by ejecting droplets of a recording liquid, so-called ink, and adhering the droplets onto a recording medium such as plain paper. An example thereof is that disclosed in Japanese Patent Publication No. 56-9429, which is proposed by the present applicant. In summary, the ink in the liquid chamber is heated to generate bubbles, thereby causing a pressure increase in the ink, and ejecting the ink from a fine capillary nozzle to perform recording.

After that, many proposals have been made utilizing such an ink flying principle. One of these proposals is, for example, a head structure disclosed in Japanese Patent Publication No. 59-43315. The publication is characterized in that it defines the amount of weight reduction of the portion of the heat acting portion which comes into contact with the liquid. However, as shown in FIG. 3 of the publication, the heating element substrate and the flow path plate are laminated. A combined head structure is shown.
Here, in the flow path plate, the plurality of grooves and the groove forming the common ink chamber are formed by cutting using a micro cutter.

However, in the case of the head structure as shown in the above publication, when a plurality of grooves forming a flow path and a groove forming a common ink chamber are formed by cutting, chipping or cracking occurs, and the yield is increased. This is not preferable because it has a high probability of causing deterioration or deterioration of accuracy. In addition, it is insufficient from the viewpoint of the accuracy of the formation position of each groove and the dimensional accuracy,
You can't expect too high quality.

[0006] In consideration of such a point, Japanese Patent Publication No. 63-36950 proposes a glass material of a substrate to be used in order to form a groove with high precision by cutting. Of the conventional example).

According to Japanese Examined Patent Publication No. 63-44067, these grooves (for flow channels and ink chambers) are formed by a so-called photolithography technique instead of cutting. One has been proposed (referred to as a second conventional example).

Further, according to Japanese Patent Application Laid-Open No. 51-55237, there is proposed a photosensitive glass which is formed by an etching technique (referred to as a third conventional example).

[0009]

However, in the case of the first conventional example, as shown in FIG. 4 of the publication, the head is completed by separately manufacturing and assembling the relay chamber (liquid chamber) block. The construction cost is high. In addition, the glass materials used are limited, and although advances and improvements in accuracy are recognized over those before that, it is still the same as the cutting method, and it is possible to improve the prevention of chipping and cracking. Is limited and inadequate.

Further, in the case of the second conventional example, unlike the cutting method, there is no chipping or cracking, and the deterioration of the positional accuracy is small, but since the photoresist is a resin material, the pattern collapses and the dimensional accuracy is high. There is a possibility that it may decrease, and in extreme cases, the channel groove may be crushed and clogged,
It becomes unreliable as a head.

Further, in the case of the third conventional example, the method of etching the photosensitive glass is more accurate than the cutting method, but still, in terms of surface roughness,
It is not sufficient for use as an ink jet flow path and is not very convenient.

[0012]

According to a first aspect of the present invention, there is provided a heat generating substrate having a heat storage layer, a heat generating layer, an electrode for energizing the heat generating layer, and a protective layer formed on the substrate.
A plurality of trapezoidal cross-sections formed by two equivalent (111) planes and one (100) plane are formed by anisotropic etching on a single crystal silicon wafer cut out in the crystal orientation plane of the (0) plane. A common liquid chamber region having a parallel channel and a channel surface communicating with these channel grooves and having a ceiling surface of (100) plane and having a depth equivalent to that of the channel groove and the common liquid chamber region. The heat generating substrate and the flow channel substrate are laminated so that the heat generating surface and the groove surface face each other.

In this case, according to the second aspect of the invention, the (100) surface of the flow channel groove and the common liquid chamber region is mirror-finished.

According to the third aspect of the invention, the substrate of the heating element substrate is a single crystal silicon wafer cut out in the crystal orientation plane of the (100) plane, which can be independently driven and corresponds to each channel groove. A plurality of heating element rows were formed in the <110> axis direction.

In these inventions, with respect to the ink inlet, in the invention according to claim 4, the opening is formed by anisotropic etching from the back surface side to the ceiling surface of the common liquid chamber region of the flow path substrate, In the invention described in claim 5, the opening is formed by laser processing on the ceiling surface of the common liquid chamber region of the flow path substrate, and in the invention of claim 6, anisotropy with respect to the side wall portion of the common liquid chamber region of the flow path substrate. The recess was formed by etching.

[0016]

In the first aspect of the present invention, a plurality of parallel channel grooves each having a trapezoidal cross section and the common liquid chamber region are cut out in the crystal orientation plane of the (100) plane in the channel substrate. Since it is formed by anisotropic etching using a single crystal silicon wafer, the characteristics of anisotropic etching can be used to perform high-precision fabrication in a single etching step in a short time, at low cost, and in a groove. Both side surfaces are also very smooth, which is convenient for the flow path of the inkjet head.

In particular, according to the second aspect of the invention, since the (100) surface of the channel groove and the common liquid chamber region is mirror-finished by appropriately selecting the etching solution, the entire channel is formed. Becomes smooth, the ink flow becomes smooth, the jet speed can be improved to stabilize the jetting, and the upper limit of the continuous driving frequency of jetting can be made higher, which is suitable for high-speed printing. Become.

In addition, in the invention of claim 3,
Regarding the heating element substrate side as well as the flow path substrate side (10
Since the single crystal silicon wafer cut out in the crystal orientation plane of the (0) plane is used and the heating element rows are aligned and formed in the <110> axial direction, the nozzle portion is cut out at the time of manufacturing the head. The dicing direction of is the crystal axis direction, that is,
The <110> axis direction can be employed, so that the dicing can be performed in the direction in which the silicon wafer is easily cracked, damage during dicing is eliminated, and the yield is significantly improved.

According to the fourth aspect of the invention, since the ink inlet port for the common liquid chamber region is formed as an opening by anisotropic etching from the rear surface side with respect to the ceiling surface thereof, a large diameter that enables sufficient ink supply. The ink inflow port can be formed with high precision.

According to the fifth aspect of the invention, since the ink inlet port for the common liquid chamber region is formed as an opening formed by laser processing on the thinnest ceiling surface, a large diameter can be obtained in a short time by a simple laser processing method. The ink inflow port can be formed.

According to the sixth aspect of the present invention, since the ink inlet port for the common liquid chamber region is formed as a concave portion by anisotropic etching on the side wall portion thereof, the flow channel groove,
It can be manufactured together with the common liquid chamber region in one anisotropic etching step, and it is possible to manufacture the flow path substrate with high accuracy and efficiency in a short time.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claims 1 to 4 will be described with reference to FIGS. The configuration and operating principle of the thermal inkjet head of this embodiment will be described with reference to FIGS. As shown in FIG. 2, this head chip 1 has a flow path substrate 3 laminated on a heating element substrate 2. Here, an ink inflow port 4 penetrating the front and back is formed in the flow path substrate 3, and a plurality of flow path grooves 6 for forming nozzles 5 are formed in parallel.
The ink inlet port 4 communicates with a common liquid chamber region 7 that is connected to the flow channel grooves 6. In addition, as shown in FIG. 1, a plurality of heating elements (heaters) 8 forming an energy acting portion corresponding to each nozzle 5 (flow channel 6) are arranged on the heating element substrate 2 so as to form a heating element row. Individually formed, each is individually connected to the control electrode 9 and commonly connected to the common electrode 10. One end of each of these electrodes 9 and 10 is led out to the end of the heating element substrate 2 and serves as a bonding pad section 11 which serves as a drive signal introducing section. Here, the heating element substrate 2
By laminating and bonding the groove surface side of the flow path substrate 3 to the heat generating surface of the flow path substrate 3, the flow path groove 6 and the common liquid chamber region 7 are closed, and the ink flow path having the nozzle 5 at the tip is formed. And an ink supply chamber are formed.

In such a head chip 1, ink jetting by a thermal ink jet is performed by the process shown in FIG. First, in the steady state, the state is as shown in FIG. 7A, and the surface tension of the ink 14 and the external pressure are in equilibrium on the orifice surface at the tip of the nozzle 5. Next, when the heater 8 is heated and the surface temperature of the heater 8 rapidly increases until the boiling phenomenon occurs in the adjacent ink layer, minute bubbles 15 are scattered as shown in FIG. Further, the adjacent ink layer that is rapidly heated on the entire surface of the heater 8 is instantly vaporized to form a boiling film,
Bubbles 15 grow as shown in FIG. At this time, the pressure in the nozzle 5 rises as much as the bubble 15 grows, the balance with the external pressure on the orifice surface is lost, and the ink column 16 starts to grow from the orifice. FIG. 6D shows a state in which the bubble 15 has grown to the maximum, and the ink 14 corresponding to the volume of the bubble 15 is extruded from the orifice surface. At this time, the heater 8 is in a state in which no current is already flowing, and the surface temperature of the heater 8 is decreasing. The maximum value of the volume of the bubble 15 is slightly behind the timing of applying the electric pulse. Eventually, the bubbles 15 are cooled by the ink 14 or the like and start contracting as shown in FIG. Ink column 1
At the front end of 6, the ink 14 advances while maintaining the extruding speed, and at the rear end, the ink 14 flows backward from the orifice surface into the ink flow path due to the decrease of the internal pressure of the ink flow path due to the contraction of the bubbles 15, and the ink column 16 Necking occurs at the base. Thereafter, as shown in FIG. 6F, the bubbles 15 further contract, the ink 14 contacts the heater 8 surface, and the heater 8 surface is further cooled. Since the external pressure is higher than the internal pressure of the ink flow path on the orifice surface, a large meniscus enters the ink flow path. The tip of the ink column 16 becomes a droplet 17 and flies toward the recording paper (not shown) at a speed of 5 to 10 m / sec. Thereafter, as shown in FIG. 6G, the ink 15 is supplied (refilled) to the orifice again by the capillary phenomenon and returns to the steady state in FIG.

Next, the heating element substrate 2, the flow path substrate 3 and the like which compose the head chip 1 will be described in detail. First, the heating element substrate 2 will be described. Generally, as a heating element substrate for this type of thermal inkjet head, a Si wafer or alumina ceramics having high thermal conductivity is used, and a glass substrate or the like whose material is easily available is used. The heating element substrate 2 is a single crystal substrate, more preferably a single crystal Si wafer widely used in the semiconductor industry field, and optimally, a single crystal Si wafer cut out in the (100) crystal orientation plane is used. . The heater 8 and the like are formed on such a single crystal Si wafer.

This Si wafer is, for example, O _{2 in} a diffusion furnace,
While flowing a gas of H ₂ O, it is exposed to a high temperature of 800 to 1000 ° C. to grow a thermal oxide film SiO ₂ on the surface of 1 to ₂ μm. This thermal oxide film SiO ₂ functions as a heat storage layer 21 as shown in FIG. 4, and prevents the heat generated by the heating element from escaping to the substrate (Si wafer) side, so that the heat is efficiently transmitted in the ink direction. It is for A heat generating layer 22 serving as the heater 8 is formed on the heat storage layer 21. As a material for forming the heat generating layer 22, a mixture of tantalum-SiO ₂ , tantalum nitride, nichrome, silver-palladium alloy, silicon semiconductor, or hafnium,
Borides of metals such as lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium and vanadium are useful. Among the metal borides, the most excellent one is hafnium boride, followed by zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride in this order. The heat generating layer 22 is formed of such a material by a method such as an electron beam vapor deposition method or a sputtering method. As the film thickness of the heat generating layer 22,
The area, the material and the shape and size of the heat acting portion, and further, so that the heat generation amount per unit time is as desired.
Although it is determined by the actual power consumption, etc.,
0.001 to 0.5 μm, more preferably 0.01 to 1
μm. In this embodiment, as an example, HfB ₂
(Hafnium boride) is used as a material and is sputtered to a film thickness of 2000 liters.

As the material forming the electrodes 9 and 10, many of the electrode materials that are normally used can be used.
Specifically, for example, Al, Ag, Au, Pt, Cu or the like is used, and these are formed at a predetermined position on the heat generating layer 22 with a predetermined size, shape and film thickness by a method such as vapor deposition. It In this embodiment, for example, Al is used to form the electrodes 9 and 10 having a film thickness of 1.4 μm by a sputtering method.

Next, these heat generating layer 22 and electrodes 9, 1
A protective layer 23 is formed on the 0. The characteristic required for the protective layer 23 is that it does not prevent the heat generated in the heater 8 portion from being efficiently transferred to the ink and that the heater 8 can be protected from the ink. Therefore, this protective layer 23
As a material forming the above, for example, silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, or the like is preferable. Using these as materials, the protective layer 23 is formed by the electron beam evaporation method or the sputtering method. Alternatively, a ceramic material such as silicon carbide or aluminum oxide may be used. The thickness of the protective layer 23 is usually 0.01 to 10 μm, preferably 0.1 to 5 μm, and optimally 0.1 to 3 μm. In this embodiment, the SiO ₂ film is formed to a thickness of 1.2 μm by the sputtering method.

Further, an anti-cavitation protection layer 24 is formed on the protection layer 23. The protective layer 24 is for protecting the heating element region from cavitation destruction due to generation of bubbles, and is formed by sputtering Ta to a thickness of 4000 Å, for example. Further, the film thickness of 2 μm is formed on the upper part of the electrode at positions corresponding to the electrodes 9 and 10.
m resin layer is formed as the electrode protection layer 25.

Next, the flow path substrate 3 will be described. The flow path substrate 3 is a single crystal Si wafer like the heating element substrate 2,
More specifically, a Si wafer cut out in the crystal orientation of the (100) plane as shown in FIG. 5 is used. This single crystal Si wafer is selected so that the X axis and the Y axis in the drawing are <110> axes orthogonal to each other, and the XY axis plane (upper and lower planes) is the single crystal (100) plane. Has been selected. By doing so, the (111) plane of the single crystal is parallel to the Y axis and is about 54.7 ° with respect to the XY axis plane.
Will intersect at an angle of.

The flow channel groove 6 formed on the flow channel substrate 3 has a trapezoidal cross section when laminated with the heating element substrate 2. Each side surface is formed as an inclined surface by an equivalent (111) plane, and the bottom surface forming the ceiling surface in the ink flow path is (100).
Formed by the surface. Here, the (111) plane has an extremely slow etching rate with an alkaline solution such as sodium hydroxide, potassium hydroxide, and humanazine as compared with other crystal planes. When the (100) plane is etched with an alkaline solution, (100) The (111) plane forming about 54.7 ° with respect to the () plane appears, and as shown in FIG. 5, the flow channel groove 6 is formed so as to have a trapezoidal cross section. The width W of the upper portion of such a trapezoidal cross section is determined by the distance between the photoresists at the time of photoetching, and is extremely accurate. Further, the depth d of the trapezoidal cross section can be easily controlled by controlling the anisotropic etching time. Furthermore, the (111) plane that appears by such etching is in a mirror surface state, which is extremely smooth and has good linearity.

Here, a method of forming a channel groove 6 having a trapezoidal cross section by using an anisotropic photoetching method using such a single crystal Si wafer will be described with reference to FIG. First, the flow path substrate 3 made of Si single crystal having the crystal orientation as described in FIG. 5 is prepared. In the state shown in FIG. 6A, the <110> axis is in the direction perpendicular to the paper surface, and the upper and lower surfaces of the substrate 3 are the (100) surface. Such a substrate 3
Is placed in a water vapor atmosphere at, for example, about 800 to 1200 ° C., and the thermal oxide film 26 is formed on the entire surface. Thermal oxide film 2
It is sufficient that the film thickness of 6 is about 0.3% of the etching depth.

Then, as shown in FIG. 3B, a photoresist is applied to the entire upper surface of the thermal oxide film 26 by a known method, and the photoresist is exposed by using a photographic plate and developed to develop a photoresist pattern. Get 27.

Then, as shown in FIG. 3C, the thermal oxide film 26 in the portion exposed by the photoresist pattern 27 is removed by an aqueous solution of hydrofluoric acid or the like to obtain an exposed portion 3a of silicon, and then, , Photoresist pattern 2
Remove 7

The substrate 3 in such a state is, for example, 5
Etch in potassium hydroxide solution at -40%, 80 ° C. As a result, the etching of the exposed portion 3a proceeds, but the etching progress rate of the (111) plane is
0 to 0.3% of the etching progress rate in the plane
Since it is about the degree, anisotropic etching is performed, and the exposed portion 3a
From the respective groove portions of the upper surface of the substrate 3 (as described above, (10
To 0) plane), an angle of tan ~ ¹ √2 (about 54.7 °) (111) plane appears. Eventually, the groove shape of the channel groove 6 formed by etching has a trapezoidal cross section as shown in FIG.

Considering the accuracy of such a trapezoidal cross section, first, the so-called undercut in the lower groove at the end of the thermal oxide film 26 is extremely small, and is about 0.2% of the etching depth of the (100) plane. There is nothing. Therefore, the width (W) of the upper portion of the trapezoidal cross section can be set to an accuracy of about ± 1 μm even if the error of the photomask is taken into consideration.

Finally, as shown in FIG. 7E, the thermal oxidation film 26 used as the etching mask is removed by an aqueous solution of hydrofluoric acid or the like to form a single crystal in which the channel groove 6 having a trapezoidal cross section is formed. The flow path substrate 3 is made of only Si. In order to actually apply such a flow path substrate 3 to the head chip 1, in order to protect the Si wafer from the ink, S
It is preferable to protect with a protective film of iO ₂ , Si ₃ N _4, or the like.

The flow path substrate 3 having the flow path groove 6 formed in the trapezoidal cross section by the anisotropic etching as described above is bonded to the heating element substrate 2 on which the heater 8 and the like are formed as described above. Alternatively, they are pressed into a laminated state. These laminated substrates 2 and 3 are cut by a dicing saw in a region slightly downstream (about 100 to 200 μm) from the heater 8 in a direction substantially perpendicular to the flow channel (flow channel groove 6). By doing so, the nozzles 5 for ejecting ink are cut out and the head chip 1 is completed. FIG. 2 shows the head chip 1 completed in this way, and FIG. 7 is a front view showing a part of the nozzle 5 for ejecting ink in an enlarged manner.

As a method of forming the ink ejection nozzle 5, as described above, the surface cut by the dicing saw is directly used as the ink ejection nozzle surface.
For example, as shown in FIG. 8, a trapezoidal ejection nozzle 28a
It is also possible to separately prepare the nozzle plate 28 on which the above is formed and to join this to the end surface of the head chip 1. Such a nozzle plate 28 is made of, for example, a resin plate (having a thickness of about 10 to 50 μm) such as polysulfone, polyether sulfone, polyphenylene oxide, and polypropylene.
The discharge nozzle 28a may be formed by irradiating an excimer laser to remove and evaporate the resin.
According to such a manufacturing method, precise processing along the trapezoidal mask pattern for the discharge nozzle 28a can be easily performed, and the highly accurate nozzle plate 28 can be obtained. The nozzle plate 28 is bonded to the cut surface of the head chip 1 with an adhesive. Alternatively, the discharge nozzle 28a may be formed by irradiating an excimer laser after the resin plate as described above is bonded to the cut surface of the head chip 1. By doing so, the complexity of aligning the flow path (flow path groove 6) with the discharge nozzle 28a is released. In addition, the discharge nozzle 28a obtained by such a manufacturing method
Is preferably equal to or slightly smaller than the size of the cross section of the ink channel in the cut surface of the head chip 1. In any case, according to the head structure in which the nozzle plate 28 is separately provided as described above, compared with the structure shown in FIG.
The stability of ink ejection is high.

According to the basic configuration of this embodiment,
Since the ink flow path is very smooth, the ink ejection performance is excellent.

With this basic structure, in this embodiment, single crystal Si cut out in the crystal orientation plane of the (100) plane is used.
The channel substrate 3 according to 1 is particularly characterized in that the common liquid chamber region 7 is formed at the same depth at the same time by the same anisotropic etching process together with the channel groove 6 having a trapezoidal cross section. That is, in the flow channel substrate 3, the pattern for forming the flow channel groove 6 and the concave portion which becomes the common liquid chamber region 7 is formed on one photomask, and the pattern is formed by only one photolithography-etching process. The flow path substrate 3 as shown in 1 is formed (however, the ink inlet 4 is basically formed in a separate step as described later).

Here, one of the important points of this embodiment is to properly select the etching solution used for anisotropic etching. As described above, the etching liquid for anisotropically etching the channel groove 6 and the common liquid chamber region 7 is generally sodium hydroxide, potassium hydroxide,
An aqueous solution of hydrazine or a mixed solution of ethylenecyamine, pyrocatechol, and water is used, but when these etching solutions are used, the etching surface (that is, the (100) surface) is generally not smooth. , It has a rough surface. On the other hand, the equivalent (111) planes on both sides are formed as a very smooth surface which is a mirror surface. Here, the (100) surface that is the bottom surface of the flow channel groove 6 and the (100) surface that is the ceiling surface of the common liquid chamber region 7 are not rough surfaces, but may be mirror-like surfaces like the (111) surface. It is considered preferable for smoothing the ink flow. Then, as a result of studying various etching solutions, it was found that etching with an aqueous solution of tetramethylammonium hydroxide gives a mirror surface (100) surface for the channel groove 6 and the common liquid chamber region 7.

Therefore, in this embodiment, the flow path substrate 3 formed by using the above-mentioned sodium hydroxide aqueous solution and the tetramethylammonium hydroxide aqueous solution are formed as the etching liquid for anisotropic etching. Two types of head chips 1 were prototyped using the flow path substrate 3 and their ink ejection performances were compared as Experiment 1 below.

(Experiment 1) Prototype Head Chip: The head chip 1 as shown in FIG. 2 was used. The flow path substrate 3 was a 20% sodium hydroxide aqueous solution at 80 ° C. for 1 hour.
Two types were used: one that was etched for 0 minutes and one that was etched with a 22% tetramethylammonium hydroxide aqueous solution at 90 ° C. for 8 minutes. Regarding the surface roughness of the (100) surface of the flow channel groove 6 and the (100) surface of the common liquid chamber region 7, the former was rough and rough, whereas the latter was finished in a smooth mirror surface state. is there.・ Nozzle size: Upper bottom 24 μm, lower bottom 59 μm, depth 2
Trapezoid of 4.7 μm ・ Heater size: 35 μm × 160 μm (resistance value is 12
0.5Ω) ・ Nozzle array density: 300dpi ・ Number of nozzles: 64 Ink used ・ Glycerin 18%, Ethyl alcohol 4.8%, Water 7
5%, C.I. I. Direct Black 154 (dye) 2.
2% composition Head drive conditions-Drive voltage V _o = 28 V-Drive pulse width P _w = 6 μs According to this Experiment 1, a head chip using the flow path substrate 3 formed by etching with an aqueous solution of sodium hydroxide is used. In the case of 1, the jet velocity becomes V _j = 11.8 m / s, and the upper limit of the drive frequency that enables stable continuous injection is F
_{While o} = 4 kHz, in the case of the head chip 1 using the flow path substrate 3 formed by etching with an aqueous solution of tetramethylammonium hydroxide, the jet velocity becomes V _j = 15.2 m / s, The upper limit of the driving frequency that allows stable continuous injection is also F _o = 7 kHz.

According to these results, the channel groove 6 and the common liquid chamber area 7 (1
Like the (111) plane, the (00) plane has a smoother mirror finish, which results in a higher jet velocity, which stabilizes the jetting, and when continuous jetting is performed, continuous driving that enables stable jetting It can be seen that the upper limit of the frequency can be set to be high, which is suitable for high-speed injection.

Further, the point of using a single crystal Si wafer cut out in the crystal orientation plane of the (100) plane as the substrate of the heating element substrate 2 which is one of the features of this embodiment will be described. In the present invention, as described above, a plurality of parallel channel trapezoidal flow channel grooves 6 and these flow channel grooves 6 are used by using the Si wafer cut out in the crystal orientation plane of the (100) plane. The flow path substrate 3 is formed by anisotropically etching the common liquid chamber region 7 communicating with the above, and is laminated on the mating heating element substrate 2, and then the nozzle portion is cut out by dicing. . The dicing direction is a direction substantially orthogonal to the direction in which the ink in the flow channel 6 flows, that is, the <110> axis direction. Therefore, there is no particular problem regarding dicing of the flow path substrate 3, but since the heating element substrate 2 is also cut by dicing at the same time, in consideration of the yield improvement at this time, it is important to select the substrate material for the heating element substrate 2. Becomes Therefore, in the present embodiment, as described above, the substrate material for the heating element substrate 2 is (10
The single crystal Si wafer cut out in the crystal orientation plane of the (0) plane is used.

Although the anisotropic etching process is not performed on the heating element substrate 2 side, the substrate material for the heating element substrate 2 is also (10) for the following reason.
The Si wafer of (0) plane is used. The first reason is the thermal conductivity. That is, Si has a higher thermal conductivity than glass, alumina ceramics, or the like, and a head that utilizes heat such as a thermal inkjet head has excellent heat dissipation characteristics, which is preferable. The second reason is the use of the (100) plane for Si wafers.
This is the property of single crystal material called cleavage. That is, as described above, when cutting out the nozzle portion by dicing, it is desirable that the dicing direction be the crystal axis direction. That is, a single crystal material such as Si generally has a property called cleavage and is easily broken along the crystal axis direction. Specifically, (100)
When the flow path substrate 3 is manufactured using the Si wafer of the surface,
110> It is easy to crack in the axial direction, so when dicing <
It can be said that it is best to cut in the 110> axial direction. On the other hand, with respect to the heating element substrate 2 that is laminated and cut at the same time as the flow path substrate 3, the heating element array is patterned using the (100) plane Si wafer so that the dicing direction is the <110> axis direction. Is best done.

Here, an example of an experiment as to whether or not the chip is broken during chip formation is shown for the case where the dicing direction is the crystal axis direction and the case where the dicing direction is not the crystal axis direction. This experiment is an experiment in which a rectangular chip is cut out from one wafer. (Experiment 2) Using a Si wafer having a diameter of 5 inches and having a thickness of 0.5 mm and having a crystal orientation plane on the (100) plane,
An experiment was performed in which 144 rectangular chips each having a size of 7 mm × 10 mm were cut by a dicing method. The dicing saw used was a DAD-2H / 5 type manufactured by Disco Corporation, the blade rotation speed was 30,000 rpm, and the blade feed speed was 2 mm / s. The blade used is NBC-Z600 (= outer diameter 52 mm x thickness 0.1 mm x inner diameter 40 mm) manufactured by DISCO. A Si wafer was attached to a dicing film, vacuum chucked on a dicing saw, and dicing was performed in two <110> axis directions orthogonal to each other with a cutting depth of 0.5 mm. As a result, all 144 chips could be made into chips without damage.

(Experiment 3) The same dicing saw as in Experiment 2,
Using a Si wafer or the like, only dicing direction <110
> 144 chips are formed as a direction that is unrelated (random) to the axial direction. As a result, 113 chips out of 144 chips have a small chipping or
Cracks occurred on the entire surface, and only 31 chips were 7 mm x 10
It was obtained as a rectangular chip with a size of mm without damage. Observation of the chip that was damaged or the like revealed that a chip or a crack was generated in the <110> axis direction.

As can be seen from the results of Experiments 2 and 3 described above, when dicing a Si wafer into chips, it is important to perform dicing in the direction of the crystal axis. That is, when the heat-generating body substrate 2 and the flow path substrate 3 are made of a single crystal material and a laminate thereof is cut out by dicing, if the dicing is performed in a direction deviating from the crystal axis direction, no damage occurs. It is clear from these experimental results that it is difficult to obtain a laminated chip. Therefore, in this embodiment, the heating element substrate 2 and the flow path substrate 3 are used.
In both cases, a Si wafer cut out in the same azimuth plane is used, and both substrates 2 and 3 are diced in the same crystal axis direction to complete the head chip 1 and improve the yield. It was done like this.

Specifically, the heating element substrate 2 in which the heater 8 and the like are formed on the Si wafer cut out with the (100) plane as the crystal orientation plane is diced in two equivalent <110> axis directions orthogonal to each other. The flow path substrate 3 in which the flow path groove 6 and the common liquid chamber region 7 are formed by anisotropic etching on the Si wafer which is formed into chips and is cut out with the (100) plane as the crystal orientation plane is orthogonal to 2 Chips obtained by dicing two equivalent <110> axes are used, and these two chips are stacked. In the laminated state, by cutting the laminated body of both substrates 2 and 3 with a dicing saw in the <110> axial direction (in other words, the direction orthogonal to the flow channel 6) in a region slightly downstream of the heater 8. ,
The ink ejection nozzle surface is cut out and formed. That is, since the two substrates 2 and 3 are laminated with their crystal axis directions aligned and cut in the same crystal axis direction, the ink ejection nozzle surface is formed without causing damage such as chipping or cracking. You can do it.

A specific example regarding this point will be shown in comparison with a comparative example. (Specific example) As a specific example, first, a heating element substrate in which 128 elements are arranged at 400 dpi using a Si wafer cut out with a diameter of 5 inches and a thickness of 0.5 mm with a (100) plane as a crystal orientation plane. 2 was produced. The tip is 7 mm x 10 mm
The size was set to 144 pieces. This Si wafer was diced in the <110> axis direction orthogonal to each other by the same method and treatment as in Experiment 2 described above, and made into chips. Next, similarly, using a Si wafer having a diameter of 5 inches and a thickness of 0.5 mm and a (100) plane as a crystal orientation plane, 400 dpi
Then, a channel substrate 3 was prepared in which 128 channels having a trapezoidal cross section and a common liquid chamber region 7 were simultaneously formed by anisotropic etching. The tetramethylammonium hydroxide aqueous solution shown in Experiment 1 was used as the etching solution for anisotropic etching. The size of the chip was 7 mm x 10 mm, and 144 chips were taken. This Si wafer was diced in the <110> axis direction orthogonal to each other by the same method and treatment as in Experiment 2 described above, and made into chips. These two chips (heater substrate chip and flow path substrate chip) were laminated so that the heat generation surface and the groove surface faced each other, and adhesively bonded to each other to obtain a laminate. Fifty such laminates were produced and the heater 8
Dicing was performed at a position of 100 μm downstream from the portion in the <110> axis direction substantially orthogonal to the flow channel groove 6 to cut out the ink ejection nozzle surface. At this time, the dicing condition is that the blade thickness is 0.25 mm and the cutting depth is 1
mm and the blade feed rate was 0.3 mm / s. As a result, the ink ejection nozzle surface could be satisfactorily cut out for all 50 nozzles without causing damage.

(Comparative Example) Twenty laminates identical to those produced in the specific example were prepared, and in the region of the flow channel, the direction not perpendicular to the flow channel groove 6 (here, about 1 from the vertical direction).
When dicing was performed in the same cutting depth as in the case of the specific example in a direction shifted by 5 °), all 20 laminates were damaged.

Further, the ink inlet 4 in the flow path substrate 3 which is one of the features of this embodiment will be described. In this embodiment, the substrate material of the flow path substrate 3 is made of Si of (100) plane.
Considering the fact that a wafer is used, the ink inlet 4 for supplying ink to the common liquid chamber area 7 also has the (100) plane, that is, the ceiling surface 7a of the common liquid chamber area 7.
It is formed as an opening by anisotropic etching. This anisotropic etching is performed from the surface (that is, the outer surface) opposite to the etching for the channel 6 and the common liquid chamber region 7 as a separate process. As a result, when viewed externally, as shown in FIG. 2, the openings are formed in a pyramidal mortar shape on the outer surface side of the flow path substrate 3.

That is, as described above with respect to the flow path substrate 3, the flow path groove 6 and the common liquid chamber region 7 are formed by anisotropic etching.
After the formation of the ink, the ink inflow port 4 is formed by performing a photolithography-etching process on the ceiling surface 7a of the common liquid chamber region 7 from the back surface side. According to the method of forming the ink inflow port 4 by anisotropic etching from the back surface side as described above, it is possible to form with high accuracy an opening having a large diameter and a sufficient ink supply capability.

Next, an embodiment of the invention described in claim 5 will be described with reference to FIG. The same parts as those shown in the above-mentioned embodiments are designated by the same reference numerals (the same applies to the following embodiments). In this embodiment, in the flow channel substrate 3 in which the flow channel groove 6 and the common liquid chamber region 7 are formed by anisotropic etching,
An opening is formed in the ceiling surface 7a of the common liquid chamber region 7 by laser processing, and this is used as the ink inlet 29.

Also in the case of this embodiment, the ink inlet 29 is formed in the ceiling surface 7a of the common liquid chamber region 7 as in the case of the above-mentioned embodiment, so that a large diameter has a sufficient ink supply capability. It can be formed as an opening. Here, although the laser processing is slightly less accurate than the anisotropic etching, it is possible to easily open in a short time,
Low cost and suitable for mass production. The laser processing machine is preferably a carbon dioxide laser or the like.

Further, an embodiment of the invention described in claim 6 will be described with reference to FIG. In this embodiment, in the step of forming the channel groove 6 and the common liquid chamber region 7 by anisotropic etching, the side wall portions 7b and 7c on both sides of the common liquid chamber region 7 (see FIG. 7A), or , The side wall portion 7d on the back side ((b) of the same figure)
The reference portion) is also formed with a concave portion, and these are used as the ink inlet 30.

That is, in the case of this embodiment, the ink inlet 30 is formed by anisotropic etching as in the case shown in FIG. 1, but in the case of this embodiment, the channel groove 6 and the common liquid are used. It has the advantage that it can be formed together when the chamber region 7 is formed, and that the production of the flow path substrate 3 can be completed by one-time anisotropic etching. By utilizing it, it becomes possible to form a single crystal with high accuracy.

[0059]

According to the first aspect of the present invention, a plurality of parallel channel grooves each having a trapezoidal cross section with respect to the channel substrate and the common liquid chamber region are cut in the crystal orientation plane of the (100) plane. Since it is formed by anisotropic etching using the single crystal silicon wafer that has been taken out, the characteristics of anisotropic etching can be utilized to make highly accurate fabrication in a short time and at low cost in a single etching process. In addition, both side surfaces of the channel groove are made very smooth, which is convenient for the channel of the inkjet head.

In particular, according to the second aspect of the invention, since the groove for channel and the (100) surface of the common liquid chamber region are made to be mirror-finished by appropriately selecting the etching liquid, The whole can be made smooth, the flow of ink can be made smooth, the jet speed can be improved to stabilize the jetting, and the upper limit of the continuous drive frequency of jetting can be made higher, and high-speed printing can be performed. It can be suitable for copying.

In addition, according to the third aspect of the invention, the heating element substrate side (10) is the same as the flow path substrate side.
Since the single crystal silicon wafer cut out in the crystal orientation plane of the (0) plane is used and the heating element rows are aligned and formed in the <110> axial direction, the nozzle portion is cut out at the time of manufacturing the head. The dicing direction of is the crystal axis direction, that is,
Since the <110> axial directions can be aligned, dicing can be performed in a direction in which the silicon wafer is easily cracked, damage during dicing is eliminated, and yield can be significantly improved.

According to the fourth aspect of the invention, since the ink inlet to the common liquid chamber region is formed as an opening by anisotropic etching from the back surface side to the ceiling surface, sufficient ink supply is possible. The large-diameter ink inlet can be formed with high accuracy.

According to the fifth aspect of the present invention, since the ink inlet port for the common liquid chamber region is formed as the opening for the ceiling surface by laser processing, the ink can be sufficiently supplied in a short time by a simple laser processing method. A large-diameter ink inlet that can be supplied can be formed.

According to the sixth aspect of the present invention, since the ink inlet for the common liquid chamber region is formed as a concave portion by anisotropic etching on the side wall portion thereof, the flow path groove and the common liquid chamber region are formed together. It can be manufactured by one anisotropic etching step, and a highly accurate and efficient flow path substrate can be manufactured in a short time.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the invention described in claims 1 to 4.

FIG. 2 is a perspective view showing a head chip.

FIG. 3 is a vertical cross-sectional side view showing the recording principle of the thermal inkjet in order.

FIG. 4 is a vertical sectional side view showing a heater and its vicinity in an enlarged manner.

FIG. 5 is a perspective view showing a crystal plane and a crystal axis direction of a flow path substrate.

FIG. 6 is a vertical cross-sectional front view sequentially showing an anisotropic etching process for a flow path substrate.

FIG. 7 is a front view showing an enlarged part of the head chip.

FIG. 8 is an exploded perspective view showing a modified example.

FIG. 9 is a perspective view of a flow path substrate showing an embodiment of the invention according to claim 5;

FIG. 10 is a perspective view of a flow path substrate showing an embodiment of the invention according to claim 6;

[Explanation of symbols]

 2 heating element substrate 3 channel substrate 4 ink inlet 6 channel groove 7 common liquid chamber region 7a ceiling surface 7b to 7d side wall portion 9,10 electrode 21 heat storage layer 22 heat generation layer 23 protective layer 29, 30 ink inlet

Claims (6)

[Claims] 1. A heat generating substrate having a heat storage layer, a heat generating layer, electrodes for energizing the heat generating layer and a protective layer formed on the substrate, and a single crystal cut out in a crystal orientation plane of a (100) plane. A plurality of parallel channel grooves each having a trapezoidal cross section and formed by two equivalent (111) planes and one (100) plane by anisotropic etching on a silicon wafer; A flow having a common liquid chamber region which is in communication with a ceiling surface of (100) face and has a depth equivalent to that of the channel groove, and an ink inflow port for flowing ink into the common liquid chamber region. A thermal ink jet head comprising a path substrate, wherein the heat generating substrate and the flow channel substrate are laminated so that a heat generating surface and a groove surface face each other. 2. A flow path groove and a common liquid chamber region (100)
The thermal inkjet head according to claim 1, wherein the surface is finished to be a mirror surface. 3. A substrate of the heating element substrate is a single crystal silicon wafer cut out in a crystal orientation plane of (100) plane, and a plurality of heating element rows which can be independently driven and correspond to each channel groove are provided. 1
10> The thermal inkjet head according to claim 1 or 2, wherein the thermal inkjet head is formed in the axial direction. 4. The ink inflow port is an opening formed by anisotropic etching from the back surface side of the ceiling surface of the common liquid chamber region of the flow path substrate.
Alternatively, the thermal inkjet head described in 3. 5. The thermal inkjet head according to claim 1, wherein the ink inlet is an opening formed by laser processing on the ceiling surface of the common liquid chamber region of the flow path substrate. 6. The thermal ink jet head according to claim 1, wherein the ink inflow port is a recess formed by anisotropic etching on the side wall of the common liquid chamber region of the flow path substrate. .