JPH06320730A - Thermal ink jet head - Google Patents

Abstract

PURPOSE:To improve a method of forming a flow groove and a common liquid chamber area on a flow path base side and further, an ink inflow orifice, in a head structure which constitutes a thermal element substrate with a thermal layer and a flow path base with a flow groove in a laminated fashion. CONSTITUTION:Flow grooves 6 running in parallel and a common liquid chamber area 7 are formed using anisotropic etching with a monocrystal silicone wafer which is cut out on the crystal azimuthal facet of a plane in a flow path base 3 laminated on a thermal element substrate 2 with a thermal layer. Thus high accuracy processing is achieved. In this case, it is ensured by making the common liquid chamber area 7 deeper than the flow groove 6 that an ink supply shortage from the common liquid chamber does not occur, if a head drive frequency becomes higher. In addition, the flow groove 6 and the common liquid chamber area 7 on a different level are formed in a single processing step, using the characteristics of anisotropic etching against the plane.

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, since the groove for the flow path and the groove for the ink chamber generally have different depths, it is necessary to perform the etching in two steps, which is a troublesome manufacturing process. Become. Although the method of etching the photosensitive glass is more accurate than the cutting method, it is still insufficient in terms of surface roughness for use as an ink jet flow channel, and is not very convenient. It's not good.

[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 parallel flow channel grooves having a V-shaped cross section formed by anisotropic etching on the single crystal silicon wafer cut out in the crystal orientation plane of the (0) plane, and communicating with these flow channel grooves. It comprises a common liquid chamber region deeper in the <100> axis direction than the flow channel groove, and a flow channel substrate having an ink inlet for flowing ink into the common liquid chamber region. The flow path substrate was laminated such that the heat generating surface and the groove surface face each other.

In this case, according to the second 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, regarding the ink inlet, in the invention described in claim 3, the opening is formed by anisotropic etching from the back surface side with respect to the ceiling surface of the common liquid chamber region of the flow path substrate. In the invention according to claim 4, 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 according to claim 5, 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.

[0015]

According to the first aspect of the invention, a plurality of parallel channel grooves and the common liquid chamber region are formed in the channel substrate (1
Since it is formed by anisotropic etching using a single crystal silicon wafer cut out in the crystal orientation plane of the (00) plane, it can be produced with high precision by utilizing the characteristics of anisotropic etching, and Both side surfaces are also very smooth, which is convenient for the flow path of the inkjet head. In addition, even if the number of grooves for the flow path is large or the head drive frequency is high, the depth of the common liquid chamber area is set to the flow path in order to improve the followability without causing insufficient ink supply from the common liquid chamber. By making it deeper than the groove, the ceiling surface of the common liquid chamber is raised. However, even if the depths of the flow path groove and the common liquid chamber region are different from each other, when anisotropic etching is performed, a V-shaped flow is obtained. The (111) faces forming the both side surfaces of the road groove are temporarily
By utilizing the property that, when exposed, the etching in that region hardly progresses any more, and the common liquid chamber region can be formed by simply continuing anisotropic etching. The etching process is enough and it can be manufactured in a short time and at low cost.

In addition, in the invention described in claim 2,
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.

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

According to the fourth aspect of the invention, since the ink inlet for the common liquid chamber region is formed as an opening formed by laser processing on the ceiling surface having the smallest wall thickness, 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 fifth 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.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claims 1 to 3 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. 9G, the ink 14 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 ,
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 for forming the electrodes 9 and 10, many of the commonly used electrode materials 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, a cavitation resistant protective layer 24 is formed on the protective 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, as shown in FIG. 5, a Si wafer cut out to the crystal orientation plane of the (100) plane 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.
It will intersect at an angle of °. The flow channel groove 6 formed on the flow channel substrate 3 has a V-shaped groove shape, and each of the two inclined surfaces of the V-shaped groove is constituted by a (111) plane.
The (111) plane has an extremely low etching rate with an alkaline solution such as sodium hydroxide, potassium hydroxide, or humanazine as compared to other crystal planes. When the (100) plane is etched with an alkaline solution, the (111) plane becomes A restricted V-shaped groove can be obtained as the channel groove 6. The width of the upper portion of such a V-shaped groove is determined by the distance between the photoresists during photoetching and is extremely accurate. The depth of the V-shaped groove is (100) plane and (111) plane.
Since it is determined by the angle formed by the surface (about 54.7 °) and the width of the upper surface, this is also extremely accurate. Moreover,
The (111) plane that appears by etching becomes extremely smooth and has good linearity.

A method of forming the channel groove 6 by the 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, for example, 8
The thermal oxide film 26 is formed on the entire surface by placing in a water vapor atmosphere at about 00 to 1200 ° C. It is sufficient that the thermal oxide film 26 has a film thickness of 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 dry plate and developed to obtain a photoresist pattern 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 the photoresist is removed. The pattern 27 is removed. The substrate 3 in such a state is etched in a potassium hydroxide solution at 5 to 40% and 80 ° C., for example. As a result, the etching of the exposed portion 3a proceeds, but the etching progress rate of the (111) plane is (1
Of the etching progress rate in the (00) plane of 0.3 to 0.4
%, The anisotropic etching results in exposed portion 3
From each groove portion of a, the upper surface of the substrate 3 (as described above, (1
(00) surface), tan ~ ¹ √2 (about 54.7 °)
The (111) plane forming the angle of appears. Eventually, the groove shape of the flow path groove 6 formed by etching becomes a trapezoidal shape as shown in FIG. Further etching,
The channel groove 6 has two (11)
1) The V-shaped groove is regulated by the surface.

Considering the accuracy of such a V-shaped groove, first, so-called undercut in the lower groove at the end of the thermal oxide film 26 is extremely small, and when using high-purity sodium hydroxide, the (100) plane It is only about 0.2% of the etching depth. Therefore, the width of the V-shaped groove (W)
Can have an accuracy of about ± 1 μm even if the error of the photomask is taken into consideration. The angle formed by the bottom of the V-shaped groove is determined by the angle formed by the (111) planes (about 70.6 °). The V-shaped depth (d) is W / √2.

Finally, as shown in FIG. 6F, the thermal oxide film 26 used as the etching mask is removed by an aqueous solution of hydrofluoric acid or the like to form the channel groove 6 having a V-shaped groove. The flow path substrate 3 is made of only crystalline 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 grooves 6 formed in the V-shaped groove shape by the anisotropic etching is formed on the heating element substrate 2 on which the heater 8 and the like are formed as described above. They are joined or pressure-welded to form 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 for forming the nozzles 5 for ejecting ink, as described above, the surface cut by the dicing saw is directly used as the nozzle surface for ejecting ink.
For example, as shown in FIG. 8, a triangular discharge nozzle 28.
It is also possible to separately prepare the nozzle plate 28 on which a is formed and to join this to the end surface of the head chip 1. Such a nozzle plate 28 is, for example, a resin plate made of polysulfone, polyether sulfone, polyphenylene oxide, polypropylene or the like (thickness is about 10 to 50 μm).
In addition, 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 triangular mask pattern for the ejection 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. The size of 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 flow path in the cut surface of the head chip 1. In any case, according to the head structure in which the nozzle plate 28 is provided separately as described above, the stability of ink ejection is higher than that shown in FIG.

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 the present embodiment, a single crystal Si cut out in the crystal orientation plane of the (100) plane is used.
With respect to the flow path substrate 3 according to FIG.
At the same time, the common liquid chamber region 7 is particularly characterized in that it is formed by anisotropic etching. That is, in the flow channel substrate 3, the flow channel groove 6 is (100) as described above.
It is formed into a V-shaped cross section by anisotropic etching of the surface. At this time, the common liquid chamber region 7 for forming the common liquid chamber is formed.
The depression for use is also formed simultaneously by continuing this anisotropic etching. At this time, the depth of the recess of the common liquid chamber region 7 (the depth in the <100> axial direction) is at least deeper than the depth of the flow channel groove 6 so as to prevent insufficient ink supply to the ink flow channel portion. Therefore, the ceiling surface of the common liquid chamber is set to be higher.

That is, when the head chip is constructed by using the flow channel substrate in which the depth of the common liquid chamber is equal to the depth of the flow channel groove (about 20 to 40 μm), the ceiling surface of the common liquid chamber is low. Insufficient supply of ink is likely to occur, and when the head is driven at a particularly high driving frequency, the ink is not ejected (idle ejection state) and unprintable portions occur, resulting in poor print quality. In this respect, as described above, by forming the depth of the common liquid chamber region 7 deeper than the flow channel groove 6, it is possible to always supply sufficient ink.

According to such a flow channel substrate structure, the flow channel groove 6 and the common liquid chamber region 7 have different steps, but because of the anisotropic etching of the (100) plane,
Only one anisotropic etching step is required. That is, if there is a difference between the depth of the flow channel groove 6 and the depth of the common liquid chamber region 7, there is a concern that the difference in etching time will be a problem. Almost no problem. The reason will be explained. As described above, the etching rate of the (111) plane of the single crystal Si cut out to the crystal orientation plane of the (100) plane is about 0.3 to 0.4% with respect to the etching rate of the (100) plane. It has an extremely slow property. Therefore, as in the present embodiment, when the flow channel groove 6 portion and the common liquid chamber region 7 portion are simultaneously patterned (photolithography) with one photomask and anisotropic etching is performed, etching is performed. Up to the stage shown in FIG. 6 (d), the depths of the channel groove 6 portion and the common liquid chamber region 7 portion are almost the same. However, the channel groove 6 is
Once the etching progresses to the stage where it becomes a complete V-shape as shown in (e), the channel groove 6 has two (11
It becomes a groove formed by the (1) plane, the (100) plane is no longer exposed at all, and thereafter, in the depth direction (<
This is because the etching hardly progresses in the direction of 100> axis direction). On the other hand, in the common liquid chamber region 7, even if etching in the depth direction hardly progresses in the V-shaped channel groove 6, the (100) plane is still exposed because the opening width is very large. <100>
Etching in the axial direction, and thus in the depth direction, will proceed at the same rate. In this way, even if the desired depth is reached on the channel groove 6 side and etching is almost stopped, the etching can be continued on the common liquid chamber region 7 side, so that the etching is easily continued to the desired depth. Only by doing so, the common liquid chamber region 7 having a deeper desired depth can be formed.
Specifically, for example, the depth of the channel groove 6 is 20 to 40 μm.
While the depth of the common liquid chamber region 7 is about 50 m
Approximately 300 μm.

A concrete example 1 based on such a viewpoint will be shown in comparison with a comparative example 1. (Specific Example 1) As a specific example 1, first, 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, a cross section V of 128 lines at 400 dpi is used.
A flow channel substrate 3 having a V-shaped flow channel groove 6 and a common liquid chamber region 7 communicating with these flow channel grooves 6 was produced. The outer dimensions of the flow path substrate 3 were 7 mm × 10 mm, and 144 pieces were taken. The depth of the flow channel groove 6 was 28 μm and the length was 2 mm (although, after being finally joined to the heating element substrate 2 and the nozzle portion was cut out by dicing, 0.8 mm was used.
Will be the length of). On the other hand, the size of the common liquid chamber area 7 is 3 mm.
The depth was 8 mm and the depth was 0.15 mm.

Such a flow path substrate 3 is formed by the photolithography-etching steps as described above, and the experimental conditions (anisotropic etching conditions) as the specific example 1 of this time are as follows. First, a 22% tetramethylammonium hydroxide aqueous solution was used as an etching solution, and the solution temperature was maintained at 90 ° C. to perform dip etching. The channel groove 6 was formed in a V shape after about 10 minutes, but the etching was continued after that for about 1 hour. As a result, the channel groove 6 has a depth of 28 μm, and the common liquid chamber region 7 has a depth of 0.15 mm. When etching is performed with such an etching solution, the bottom surface (ceiling surface) of the common liquid chamber region 7 is also (111).
The surface roughness similar to that of the surface was obtained.

On the other hand, in addition to such a flow path substrate 3, again, a Si wafer cut out in the crystal orientation plane of the (100) plane is used, and 128 rectangular heating elements of 28 μm × 120 μm size at 400 dpi are formed. A heating element substrate 2 in which elements were arranged was produced. Here, the longitudinal direction and the lateral direction of the heating element are patterned so as to be orthogonal to the <110> axial direction, and the direction in which 128 heating elements are arranged in one row (arrangement direction) is also the <110> axial direction. Is set to be

The heating element substrate 2 and the flow path substrate 3 manufactured in this way are laminated so that the heating surface and the groove surface face each other, and adhesively bonded to manufacture the head chip 1, and an ink ejection experiment is carried out. Drive frequency of one heating element to nozzle is 8k
When the entire surface was printed by driving at a frequency of Hz, ink ejection was stably performed for all, and a clear solid image was obtained. By the way, in this ink ejection experiment, not all 128 heating elements were driven simultaneously,
It is assumed that 32 blocks are divided into 4 blocks and driven separately.

(Comparative Example 1) In the process of manufacturing the flow path substrate described in the specific example 1, all anisotropic etching is completed in 10 minutes, and the depths of the flow path groove and the common liquid chamber region are both set. An ink ejection experiment was conducted under the same driving conditions using a head chip in which a flow path substrate having a thickness of approximately 28 μm was produced and the heating element substrate produced as described in Example 1 was used. Occurs, and a clear solid image cannot be obtained. However, if you drastically reduce the drive frequency to 1.6 kHz and experiment again,
A beautiful solid image was obtained.

Also from these results, if the depth of the common liquid chamber region 7 is made deeper than the depth of the flow channel groove 6 as in the present embodiment, the ink supply is not insufficient and the frequency is high (high). It can be seen that the head can be driven at the driving frequency).

Further, a 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 the present invention will be described.
In the present invention, as described above, using the Si wafer cut out in the crystal orientation plane of the (100) plane, the plurality of parallel channel grooves 6 and the channel grooves 6 are connected to each other. The flow path substrate 3 in which the deeper common liquid chamber region 7 is formed by anisotropic etching is produced, and the nozzle portion is cut out by dicing after being laminated with the heating element substrate 2 on the other side. 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, as the substrate material for the heating element substrate 2, the single crystal Si wafer cut out to the (100) crystal orientation plane is used as in the flow path substrate 3 side. It was done like this.

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 1) A Si wafer having a diameter of 5 inches and having a thickness of 0.5 mm and having a crystal orientation plane on a (100) plane was used.
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 2) The same dicing saw as in Experiment 1,
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 above experimental results, Si
It can be seen that when dicing the 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 the present embodiment, both the heating element substrate 2 and the flow path substrate 3 use Si wafers cut out in the same azimuth plane,
Moreover, the head chip 1 is completed by dicing both substrates 2 and 3 in the same crystal axis direction, and the yield is improved.

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 2) As a specific example 2, first, a Si wafer cut out with a diameter of 5 inches and a thickness of 0.5 mm and having a (100) plane as a crystal orientation plane is used, and heat generated by arranging 128 elements at 400 dpi. The body substrate 2 was produced. The tip is 7 mm x 10
The size of mm was 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 1 described above to form a chip. 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, 128 channels of the channel grooves 6 were formed as V-shaped grooves by anisotropic etching, and the channel substrate 3 having the common liquid chamber region 7 formed by the anisotropic etching was prepared. 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 1 described above to form a chip. 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 dicing was performed at a position of 100 μm downstream from the heater 8 in the <110> axial 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, the cutting depth was 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 2) 20 same laminates as those produced in Example 2 were prepared, and in the region of the flow channel, the direction not perpendicular to the flow channel groove 6 (here, about from the vertical direction) When dicing was performed in the same cutting depth as in the case of Example 2 in the direction shifted by 20 °), all 20 laminates were damaged.

Further, the ink inlet 4 in the flow path substrate 3 which is one of the features of the present invention will be described. In the present embodiment, considering that the (100) plane Si wafer is used as the substrate material of the flow path substrate 3, the ink inlet port 4 for supplying ink to the common liquid chamber region 7 is also considered. , (100) surface, that is, the ceiling surface 7a of the common liquid chamber region 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 4 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. Also,
Since such a ceiling surface 7a is thinned by performing the anisotropic etching process for a long time, it can be easily opened in a short time by a laser processing method.
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 5 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) in the 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.

[0057]

According to the first aspect of the present invention, a plurality of parallel flow channel grooves and a common liquid chamber region are formed on the flow channel substrate.
Since it is formed by anisotropic etching using a single crystal silicon wafer cut out in the crystal orientation plane of the (100) plane, it can be manufactured with high accuracy by utilizing the characteristics of anisotropic etching, and the flow Both sides of the channel groove can be made very smooth to make it convenient for the flow channel of the inkjet head, and the common liquid chamber area should be deeper than the channel groove. Since the ceiling surface of the common liquid chamber is raised, it is possible to improve the followability without causing a shortage of ink supply from the common liquid chamber even if the number of channels for the flow passage is increased or the head drive frequency is increased. Even if the depths of the channel groove and the common liquid chamber region are different as described above, when anisotropic etching is performed, the (111) planes forming both side surfaces of the V-shaped channel groove are once exposed. Once formed, etching of that area By utilizing the property that it hardly progresses any more, the common liquid chamber region can be formed by simply continuing the anisotropic etching, and only one anisotropic etching step is required, which can shorten the time and cost. It can be produced by

In addition, according to the second 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 third 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 to the ceiling surface, sufficient ink supply is possible. The large-diameter ink inlet can be formed with high accuracy.

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 laser processing on the ceiling surface having the smallest wall thickness, a short laser processing method is used. It is possible to form a large-diameter ink inflow port capable of supplying sufficient ink in time.

According to the fifth aspect of the present invention, since the ink inlet for the common liquid chamber region is formed as a recess 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 3.

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 4;

FIG. 10 is a perspective view of a flow path substrate showing an embodiment of the invention as set forth in claim 5;

[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 sidewall 9 and 10 electrode 21 heat storage layer 22 heat generating layer 23 protective layer 29 and 30 ink inlet

Claims (5)

[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 flow channel grooves having a V-shaped cross section formed by anisotropic etching on a silicon wafer, and a common that communicates with these flow channel grooves and is deeper than these flow channel grooves in the <100> axial direction. The flow path substrate is formed with a liquid chamber region and an ink inlet for flowing ink into the common liquid chamber region, and the heat generating substrate and the flow channel substrate are opposed to each other by a heat generating surface and a groove surface. The thermal inkjet head is characterized by being laminated in this manner. 2. A 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, wherein the thermal inkjet head is formed in the axial direction. 3. The thermal ink according to claim 1, wherein the ink inflow port is an opening formed by anisotropic etching from the back surface side with respect to the ceiling surface of the common liquid chamber region of the flow path substrate. Inkjet head. 4. 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. 5. 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.