JPH0768760A - Thermal ink jet head - Google Patents

Abstract

PURPOSE:To provide a head having high yield without damage at the time of cutting in a head structure in which a heat generator board having a heat generating layer, etc., and a channel board having channel grooves are laminated and cut to form a discharge nozzle. CONSTITUTION:A thermal ink jet head 1 is composed by a heat generator board 2 in which a heat storage layer, a heat generating layer, electrodes for energizing the generator layer and a protective layer are formed on a single crystalline board, and a channel board 3 in which channel grooves 6 are formed on the crystalline board cut in the same crystal azimuth surface as that of the crystalline board by anisotropically etching in such a manner that the boards 2 and 3 are aligned in a crystalline axial direction and the heat generating surface and the groove surface are so laminated as to be opposed to each other and a laminate is cut perpendicularly to the grooves 6 to form an ink channel opening.

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. Among these suggestions,
For example, JP-A-56-123869 and JP-A-57-
No. 43876, JP-A-57-212067,
JP-A-57-212068 and JP-A-57-212
In JP-A-069, JP-A-58-220754 and JP-A-58-220756, an ink flow path pattern is formed on a heating element substrate by a photolithography technique, and a glass plate is formed thereon. An ink flow path and nozzles are formed by mounting a top plate such as the above and covering it.

However, when the ink flow path pattern is formed by the photolithography technique, it is necessary to form a resist pattern having a thickness of several tens of μm. Therefore, unlike the case of forming a resist pattern having a thickness of about 1 μm, which is performed in the field of semiconductor industry, it is very difficult to form an accurate ink flow path pattern.
In addition, after forming such a pattern, there is a problem that the pattern collapses when the top plate is attached as a lid,
It is difficult to form a highly accurate ink flow path and nozzle.

In consideration of such a point, Japanese Patent Laid-Open No. 2-671
The applicant of the present invention has proposed a method of manufacturing a flow channel substrate as shown in Japanese Patent Laid-Open No. 40. This is single crystal silicon (S
The V-shaped groove using the anisotropic etching of i) is used as the flow path. In the ink flow path formed in this manner, the surfaces forming the two surfaces on both sides of the V-shaped groove are (111) surfaces, which can be formed with the accuracy of a single crystal, and the surfaces are also very smooth. When considered as a flow path of, it becomes very convenient. Further, the present applicant has proposed that the groove formed in the flow path substrate made of single crystal silicon has a trapezoidal shape formed by two equivalent (111) planes and one (100) plane. There is.

[0007]

However, even in the case of such a proposal example, in practice, how to take out the flow path substrate having the V-shaped groove or the trapezoidal groove, or how Assemble to
Whether or not the head can be completed efficiently has not been sufficiently studied, and the yield of the flow path substrate itself or the head in which the flow path substrate is assembled is not so high.

[0008]

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, electrodes for energizing the heat generating layer, and a protective layer formed on a single crystal substrate, A flow path substrate having grooves for flow paths formed by anisotropic etching on a single crystal substrate cut out in the same crystal orientation plane as the single crystal substrate. The thermal ink jet head was constructed by aligning the directions and stacking so that the heat generating surface and the groove surface faced each other, and cutting this laminate in a direction substantially perpendicular to the flow channel groove to form an ink flow channel opening.

In this case, according to the second aspect of the present invention, both the single crystal substrate forming the heating element substrate and the flow path substrate (10
A single crystal silicon wafer cut out in the crystal orientation plane of the (0) plane was laminated on both single crystal substrates with the <110> axis directions aligned.

Further, in the invention according to claim 3, the single crystal substrate is a single crystal silicon wafer cut out in the crystal orientation plane of (100) plane, and the channel groove is a V-shaped groove, The flow path substrate was made into chips by dicing in two orthogonal <110> axis directions.

On the other hand, in the invention according to claim 4, the single crystal substrate is a single crystal silicon wafer cut out in the crystal orientation plane of the (100) plane, and the channel groove is a trapezoidal groove. The flow path substrate was made into chips by dicing in two orthogonal <110> axis directions.

Further, according to the present invention, the flow path substrate is made into chips by the chip forming grooves formed deeper than the flow path grooves by anisotropic etching.

Further, in these inventions, claim 6
In the described invention, the flow path substrate has a recognition means for recognizing the mounting direction to the heating element substrate from the side opposite to the groove surface having the flow path groove.

On the other hand, according to the invention of claim 7, a positioning pattern formed by photofabrication on the heating element substrate and a penetrating formation on the flow path substrate at a position corresponding to the positioning pattern by anisotropic etching. The position alignment means is provided in combination with the positioned transparent see-through section.

[0015]

According to the invention of claim 1, the heating element substrate and the flow path substrate are formed of a single crystal substrate cut out in the same crystal orientation plane, and are laminated with their crystal axis directions aligned and laminated. Since the ink flow path opening is formed by cutting the liquid crystal substrate in a direction substantially perpendicular to the flow path groove on the flow path substrate, the head structure in which both are laminated and cut to form the discharge nozzle has the same crystal axis direction. The head becomes a high-yield head without being damaged during the cutting.

In particular, according to the second aspect of the present invention, both the heating element substrate and the flow path substrate are made of a single crystal silicon wafer, and the single crystal substrates are laminated so that the <110> axis direction is aligned. When forming the road opening,
110> A cut is made in the axial direction, no damage occurs at the time of cutting, and the yield is further improved.

Further, in the invention according to claim 3 or 4, the single crystal substrate is a silicon wafer cut out in the crystal orientation plane of the (100) plane, and the channel groove is V-shaped in the (100) plane. When a chip of a flow path substrate formed as a groove or a trapezoidal groove is taken out from a silicon wafer, it is made into chips by dicing in two orthogonal <110> axial directions. A flow path substrate can be obtained with a yield.

Further, in the invention according to claim 5,
Since the channel substrate was made into chips by the chipping groove formed deeper than the channel groove by anisotropic etching,
The process for forming the groove for the flow path is completed, and it is not necessary to perform dicing or the like later, and the process is shortened. Also, because the chips are made into chips by anisotropic etching,
The obtained flow path substrate chip has high dimensional accuracy.

On the other hand, according to the sixth aspect of the invention, when the flow path substrate is laminated and mounted on the heating element substrate, even if the flow path substrate is opaque, it can be visually recognized from the outside opposite to the groove surface. Since the surface to be obtained has a recognition means for recognizing the mounting direction of the channel groove or the like, it is possible to easily perform the stacked mounting on the heating element substrate.

Further, according to the invention of claim 7, since the position matching means is provided by the combination of the positioning pattern formed on the heating element substrate and the positioning see-through portion penetratingly formed on the flow channel substrate, the flow channel substrate is opaque. Even in this case, the heat generating portion and the flow path groove can be accurately aligned during assembly. In particular, since the positioning see-through portion on the side of the flow path substrate is formed by anisotropic etching, the positioning see-through portion has much higher precision than that obtained by simple through-hole machining such as laser machining, and highly accurate position alignment is possible.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. The configuration and operating principle of the thermal inkjet head of this embodiment will be described with reference to FIGS. This head chip 1 has a heating element substrate 2 as shown in FIG.
The flow path substrate 3 is laminated on top. Here, an ink inlet 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. The ink inlet port 4 communicates with an ink supply chamber region which is connected to the flow channel grooves 6. In addition, as shown in FIG. 2, a plurality of heating elements (heaters) 8 that form an energy acting portion are formed on the heating element substrate 2 corresponding to each nozzle 5 (flow channel groove 6), and each of them is individually formed. It is connected to the control electrode 9 and the common electrode 10 in common. 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. By laminating and bonding the groove surface side of the flow path substrate 3 on the heat generating surface of the heat generating substrate 2 so as to face each other, the flow path groove 6 and the ink supply chamber region are closed, and the nozzle is provided at the tip. An ink flow path having 5 and an ink supply chamber 7 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 by the amount of growth of the bubble 15, 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 leading end of 6, the ink 14 moves forward while maintaining the extruding speed, and at the trailing end, the ink 14 flows backward from the orifice surface into the ink flow path due to the decrease in 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 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 the heat generated by the heating element is applied to the heating element substrate 2
This is to prevent heat from escaping to the side so that heat can be efficiently transmitted in the ink direction. This heat storage layer 2
A heat generating layer 22 serving as the heater 8 is formed on the surface 1. As a material forming the heat generating layer 22, tantalum-SiO
Mixture of _two , tantalum nitride, nichrome, silver-palladium alloy, silicon semiconductor, or hafnium, lanthanum, zirconium, titanium, tantalum, tungsten,
Borides of metals such as 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. The film thickness of the heat generating layer 22 is determined by the area, the material and the shape and size of the heat acting portion, and the actual power consumption so that the heat generation amount per unit time is as desired. But usually 0.00
The thickness is 1 to 0.5 μm, and more preferably 0.01 to 1 μm. In this embodiment, as an example, HfB ₂ (hafnium boride) is used as a material and is formed into a film having a thickness of 2000 Å by sputtering.

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, 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 was selected so that <110> in which the X axis and the Y axis in the figure were orthogonal to each other, and the XY axis plane (upper and lower planes) was the (100) plane of the single crystal. 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 V-shaped groove shape.
Each of the two inclined surfaces is composed of a (111) surface. (1
The 11) plane has an extremely slow etching rate with an alkaline solution such as sodium hydroxide, potassium hydroxide, and humanazine as compared to other crystal planes. When the (100) plane is etched with an alkaline solution, it is regulated by the (111) plane. The V
A 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. Further, since the depth of the V-shaped groove is determined by the angle (about 54.7 °) formed by the (100) plane and the (111) plane and the width of the upper surface, this is also extremely accurate. Furthermore, 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. 3F, 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. At this time, the heating element substrate 2 and the flow path substrate 3 are formed of <110> of both substrates.
Laminated and bonded in the same axial direction. 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 ink flow path opening, here the nozzle 5 for ejecting ink, is cut out, and the head chip 1 is completed. FIG. 1A shows the head chip 1 completed in this way, and FIG. 1B is an enlarged front view showing a part of the nozzle 5 for ejecting ink.

As a method of forming the nozzles 5 for ejecting ink, as described above, the surface cut by the dicing saw (ink flow passage opening surface) is directly used as the nozzle surface for ink ejection. As shown in FIG. 7, a nozzle plate 28 having triangular discharge nozzles 28a may be separately prepared and joined to the end surface of the head chip 1 where the ink flow path opening is cut and formed. 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. Further, 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.

Next, a chip forming process according to the invention of claim 3 which is one of the features of this embodiment will be described. In this embodiment, both the heating element substrate 2 and the flow path substrate 3 are formed of a single crystal material, specifically, a Si wafer. Therefore, the property of the single crystal is mechanically brittle, and its removal (chip separation) requires careful attention. In this regard, in this embodiment, in particular, a method of separating the flow path substrate 3 from the Si wafer into the flow path substrate chips is devised.

First, the single crystal material generally has a property called cleavage and is easily cracked in the direction of the crystal axis. As in the present embodiment, S of the (100) plane
If the flow path substrate 3 is manufactured using an i-wafer, the Si wafer is easily broken in the <110> axis direction. Therefore, in the present embodiment, when forming a minute flow path substrate chip from a Si wafer, it is devised to form a dicing groove in the direction of the crystal axis, which is easily broken, to form a chip. That is, dicing grooves are formed in the two orthogonal <110> axis directions to form a rectangular channel substrate chip.

Correspondingly, dicing grooves are formed in the two <110> axial directions on the (100) plane Si wafer on the heating element substrate 2 side as well as on the flow path substrate 3 side. , So as to form a rectangular heating element substrate chip.

Here, an experimental example for chip formation is shown. (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
When chips are formed from a wafer, it is important to perform dicing in the crystal axis direction. Therefore, as in this example, Si cut out with the (100) plane as the crystal orientation plane
When the flow path substrate 3 having the flow path grooves 6 formed on the wafer is cut from a Si wafer to obtain chips, dicing in two orthogonal <110> axis directions yields a high yield. Becomes In addition, the heating element substrate 2 made of a Si wafer cut out with the (100) plane as the crystal orientation plane is
When cutting from an i-wafer to obtain chips, the
If dicing is performed in two equivalent <110> axis directions, the yield will be high.

The dicing process (cutting out of the ink discharge nozzle surface) of the head chip 1 according to the first aspect of the present invention, which is one of the features of this embodiment, will be described. In the present embodiment, both the heating element substrate 2 and the flow path substrate 3 are made of a single crystal material, and the substrates 2 and 3 are laminated and the ink ejection nozzle surface is cut out by dicing. At this time, as can be seen from the above experimental results, if dicing is performed in a direction deviating from the crystal axis direction during dicing, it becomes difficult to obtain a head chip (a laminate of two substrates) without damage. . In this respect, in the present embodiment, both the heating element substrate 2 and the flow path substrate 3 are Si cut out in the same azimuth plane.
A wafer is used as a base, and both substrates 2 and 3 are made into chips by performing dicing on the same crystal axis.

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 is formed into chips and is formed with the flow path groove 6 by anisotropic etching on the Si wafer cut out with the (100) plane as the crystal orientation plane.
Chips obtained by dicing two equivalent <110> axes are used, and these two chips are stacked. In the laminated state, in the region slightly downstream of the heater 8 portion, in the <110> axial direction (in other words, the flow path groove 6).
Both substrates 2, with a dicing saw in the direction orthogonal to
By cutting the laminate of No. 3, 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 relating to this point will be shown in comparison with a comparative example. (Specific Example 1) As a specific example, first, a heating element 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. Substrate 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 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, the flow path substrate 3 was formed by anisotropically etching the flow path grooves 6 corresponding to 128 V-shaped grooves. The tip is
The size of 7 mm x 10 mm was set to 144 pieces. This Si
The wafer is orthogonalized by the same method and processing as in Experiment 1 described above.
110> Dicing was performed in the axial direction to form chips. These two chips (heater substrate chip and flow path substrate chip) are laminated so that the heat generating surface and the groove surface face each other,
Adhesive bonding was performed 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 is 1 mm, and the blade feed speed is 0.3 mm.
Except for mm / s, it was the same as in Experiment 1. As a result, the ink ejection nozzle surface could be satisfactorily cut out for all 50 nozzles without causing damage.

(Comparative Example) Twenty pieces of the same laminate as that prepared in Example 1 were prepared, and the channel groove 6 was formed in the channel region.
When the dicing was performed in a direction not perpendicular to the above (here, a direction deviating from the vertical direction by about 20 °) with the same cutting depth as in the specific example 1, all 20 laminated bodies were damaged. It is a thing.

Further, the chipping process according to the invention of claim 5 which is one of the features of the present invention will be described. This is particularly related to chip formation of the flow path substrate 3,
Although the above-described chip forming process is made into chips by dicing, the anisotropic etching for forming the channel grooves 6 and the like is used here. As described above, the flow path substrate 3 of this embodiment having the flow path grooves 6 is formed by anisotropic etching. Therefore, here S
By utilizing this anisotropic etching even when the flow path substrate is made into chips from the i-wafer, it is possible to easily form chips with high precision without requiring a separate step.

FIG. 8 shows an example thereof. In the anisotropic etching process of forming the channel groove 6 as a V-shaped groove on the Si wafer, the channel groove 6 is formed at the size contour position of the channel substrate 3. A groove much deeper than the above, in this case, a V-shaped groove having a depth that reaches the bottom surface of the Si wafer is formed as the chip forming groove 30, and the chip forming groove 30 is separated into chips, and each channel substrate 3 is formed.

In order to form a deep and large groove such as the chip forming groove 30, the width of the exposed portion 3a of the Si wafer may be increased in the anisotropic etching process shown in FIG. Further, if there is a difference between the depth of the channel groove 6 and the depth of the chip forming groove 30, there is a concern that a difference in etching time will be a problem, but in reality, such a difference in etching time is almost eliminated. It doesn't matter. The reason is that once a V-shaped groove such as the channel groove 6 is formed (when anisotropic etching reaches the lower end of the V-shaped groove), that V-shaped groove is formed.
This is because the V-shaped groove is a groove formed by two (111) planes, so that the etching is almost stopped and the groove hardly progresses further. This is because the (111) plane has an extremely slow etching rate as compared with the other planes. Therefore, by dipping the Si wafer in the etching solution for a while even after the channel groove 6 is substantially formed, the chipped groove 30 can be treated with almost no etching of the channel groove 6. As long as the exposed portion 3a of the (100) plane is exposed, the etching proceeds. Thereafter, when the etching progresses until the lower end of the dicing groove 30 reaches the bottom surface of the Si wafer, the etching is finished, and the dicing of the flow path substrate 3 is finished.

By the way, if etching is performed up to the bottom surface of the Si wafer to form the dicing groove 30, all the chips will be scattered at the end of the etching. If the etching tank structure is such that it is possible to easily accommodate all the disjointed chips in the etching tank in this way, but when using an etching tank in which the disassembled chips are difficult to accommodate, for example, As shown in FIG.
The chip forming groove 31 may be formed by stopping the etching at a depth in the middle of the i-wafer. Such chip forming groove 3
In the case of No. 1, if a slight bending force is applied to the chip forming groove 31, it can be easily separated into chips by the cleavage characteristic of the single crystal.

Further, as a planar pattern for forming such a chipping groove 30, for example, as shown in FIG. 10, Si is formed by discontinuously forming a cross shape while leaving a slight holding portion 30a. Even if the etching for the chip forming groove 30 is performed up to the bottom surface of the wafer, it may be prevented from being separated. It is easy to chip-separate the holding portion 30a in a later step.

Further, it is one of the features of the present invention.
The efficiency of the stacking process for manufacturing the head chip 1 according to the described invention will be described. In this embodiment, since the flow path substrate 3 is formed of the Si wafer as described above, it is opaque unlike a glass plate or the like. When stacked on the substrate 2, it is inconvenient because the position where the channel groove 6 is formed cannot be recognized from the upper surface (back surface) side, and the assembly process takes more time than necessary. Therefore, here, for example, the position of the ink inflow port 4 is simply deviated from the central position (the position where the diagonal lines intersect) in the rectangular chip of the flow path substrate 3, specifically, the position opposite to the ink ejection port. By forming the ink inflow port 4 at the position shifted to the rear side, the ink inflow port 4 is used as a recognition means so that the directionality when the flow path substrate 3 is laminated and assembled can be understood. As a result, even if the flow path substrate 3 is opaque, the flow path substrate 3 can be stacked and mounted on the heating element substrate 2 in the correct direction, and work efficiency is improved.

In addition, as shown in FIGS. 11 (a) and 11 (b), for example, the notch 3 is formed at an appropriate portion such as a corner or a side of the flow path substrate 3.
By forming 2a and 32b as the recognition means, it is possible to easily recognize from the outside the mounting directionality such as at which position the channel groove 6 is located. Thus, the notches 32a and 32b can be formed as they are by using the anisotropic etching process, and no special process is required.

Further, the position alignment method in the assembly process according to the present invention, which is one of the features of the present invention, will be described. This is so that even if the flow path substrate 3 made of a Si wafer is opaque, the flow path groove 6 can be assembled with the heaters 8 being properly aligned. First, on the heating element substrate 2, four L-shaped positioning patterns 33 are formed by photofabrication at positions corresponding to the four corners of the flow path substrate 3. That is, these positioning patterns 33 have sides in the biaxial directions of the X axis and the Y axis. Further, the positions of these positioning patterns 33,
Corresponding to the shape, the four corners of the flow path substrate 3 are formed with four positioning see-through portions 34 which are notched (penetrated) in the shape of a corner by using anisotropic etching used in the forming process, and the corresponding positions are formed. Positioning pattern 33 and positioning see-through part 3
Four pairs of position aligning means 35 are formed by a pair of four. That is, the positioning see-through part 34 also includes the positioning pattern 3
It is formed so as to have sides that should correspond to the sides of the three X-axis and Y-axis in the biaxial direction.

With such a configuration, when the flow path substrate 3 is laminated on the heat generating substrate 2 as shown in FIG. 12 to be assembled, each position aligning means 35, as shown in FIG. It suffices to align the respective sides of the positioning see-through portion 34 so as to correspond to the positions of the respective sides of the positioning pattern 33 in the biaxial direction, so that the flow path groove 6 and the heater 8 can easily have a correct positional relationship. It can be aligned and assembled. Here, since the anisotropic etching process is used in the flow path substrate 3, a separate process is not required, and the positioning see-through part 34 having higher positional accuracy can be formed as compared with the case of laser processing or the like. Become.

The positioning see-through portion is not limited to the one formed at the four corners of the flow path substrate 3 as shown in FIGS. 12 and 13, and for example, the flow path groove 6 as shown in FIG. The positioning see-through portion 36 may be formed in a rectangular hole shape by anisotropic etching at four positions that do not hinder the positioning (the positioning pattern 33 shown in FIG. 12 and the like is formed at the corresponding positions of these positioning see-through portions 36). ).

In the above description, the flow channel groove 6 in the flow channel substrate 3 is formed as a V-shaped groove. However, as shown in FIG. 15 etc., the trapezoidal channel flow channel groove 6 is formed. The above-mentioned dicing process and the like can be similarly applied to the same (corresponding to the invention of claim 3). Here, a method of forming the channel groove 6 with such a trapezoidal groove will be described.

First, also in this case, as the flow path substrate 3, a single crystal Si wafer, more specifically, as shown in FIG.
As shown in FIG. 16 corresponding to, the Si wafer cut out in the crystal orientation of the (100) plane is used. This single crystal S
In the i-wafer, the X axis and the Y axis in the figure are orthogonal to each other.
110> axis, and the XY axis planes (upper and lower planes) are the single crystal (100) plane. 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 is shaped so as to have a trapezoidal cross section when laminated with the heating element substrate 2, but the two trapezoidal cross sections are formed. 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 etching rate of the (111) plane by the alkaline solution is extremely slower than that of the other crystal planes, and when the (100) plane is etched by the alkaline solution, it forms about 54.7 ° with respect to the (100) plane. (1
11) surface appears, and as shown in FIG. 16, the flow channel groove 6 is formed so as to have a trapezoidal cross section. The width W ₁ 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 for forming the channel groove 6 having a trapezoidal cross section by the anisotropic photoetching method using such a single crystal Si wafer will be described with reference to FIG. Basically, the formation method described with reference to FIG. 6 may be used, and the steps shown in FIGS.
The procedure is the same as in (d). However, as an etching solution for performing anisotropic etching, sodium hydroxide,
Instead of potassium hydroxide or the like, an aqueous solution of tetramethylammonium hydroxide is used. According to this, in addition to the (111) surface that is mirror-finished by anisotropic etching,
This is because it has been found that the (100) surface forming the channel ceiling surface can also be finished in a very smooth state. FIG. 17
Considering the accuracy of the trapezoidal groove as shown in (d), 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 ₁ 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.

After this, unlike the case of the V-shaped groove, as shown in FIG.
At the stage shown in (d), the etching is completed, and finally, as shown in (e) in the figure, the thermal oxide film 26 used as the etching mask is removed by an aqueous solution of hydrofluoric acid or the like to form a trapezoidal cross section. The flow path substrate 3 is made of only single crystal Si in which the groove 6 is formed. In addition, such a flow path substrate 3
In order to actually apply the above to the head chip 1, it is preferable to protect the Si wafer from the ink with a protective film of SiO ₂ , Si ₃ N _4, or the like.

The flow path substrate 3 having the flow path grooves 6 thus formed as trapezoidal grooves by anisotropic etching is
As in the case described above, the heating element substrate 2 is bonded or pressure-contacted to form a laminated state. At this time, the heating element substrate 2 and the flow path substrate 3 are laminated and joined so that the <110> axis directions of both substrates are aligned. These laminated substrates 2,
3 is slightly downstream from the heater 8 part (100 to 20
In a region of about 0 μm), the nozzle 5 for ejecting ink is cut out by cutting with a dicing saw in a direction substantially perpendicular to the flow path (groove 6 for flow path), and the head chip 1 is completed. FIG. 15A shows the head chip 1 completed in this way, and FIG. 15B is an enlarged front view showing a part of the nozzle 5 for ejecting ink.

As for the method of forming the nozzles 5 for ejecting ink, in this case as well, in accordance with the case shown in FIG. 7, as shown in FIG. 18, a nozzle plate 28 having trapezoidal ejection nozzles 28b is formed. Prepared separately, and this is head chip 1
You may make it join to an end surface.

Even when the flow path substrate 3 having the flow path groove 6 formed by such a trapezoidal groove is used, similar to the case of the V-shaped groove, anisotropic etching is performed on the (100) plane of the Si wafer. As it is formed, it is very accurate,
At the same time, the flow path surface becomes very smooth, which makes it ideal as an ink flow path. In particular, the trapezoidal groove has an advantage over the V-shaped groove in that traps of bubbles generated in the heater 8, that is, bubbles remaining in the vicinity of the flow passage ceiling surface are reduced.

[0063]

According to the first aspect of the present invention, 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 single crystal substrate, and the single crystal. It is composed of a flow channel substrate in which a channel groove is formed by anisotropic etching on a single crystal substrate cut out in the same crystal orientation plane as the substrate, and the heating element substrate and this flow channel substrate are arranged in the crystal axis direction. Align them and stack them so that the heating surface and the groove surface face each other.
By cutting this laminate in a direction substantially perpendicular to the flow channel groove to form an ink flow channel opening to form a thermal inkjet head, the heating element substrate and the flow channel substrate are cut out in the same crystal orientation plane. Since it is formed of a single crystal substrate, both substrates are cut in the same crystal axis direction in a head structure in which both substrates are stacked and cut to form a discharge nozzle,
It is possible to provide a head having a high yield without causing damage at the time of cutting.

In particular, according to the second aspect of the invention, since the single crystal substrates made of single crystal silicon wafers are laminated on the heating element substrate and the flow path substrate so that the <110> axis direction is aligned, the ink is cut by cutting. <1 when forming the channel opening
10> A cut is made in the axial direction, no damage occurs at the time of cutting, and the yield is further improved.

According to the third or fourth aspect of the present invention, the single crystal substrate is a silicon wafer cut out in the crystal orientation plane of the (100) plane, and the channel groove is V-shaped in the (100) plane. When the chip of the flow path substrate formed as the groove or trapezoidal groove is taken out from the silicon wafer, it is made into chips by dicing in two equivalent <110> axial directions which are orthogonal to each other. Without
The flow path substrate can be manufactured with a high yield.

According to the fifth aspect of the invention, since the flow path substrate is made into chips by the chip forming groove formed deeper than the flow path groove by anisotropic etching, the flow path groove is formed. The size of the obtained flow path substrate chip can be shortened by dicing etc. as a separate process later, the process can be shortened, and chips can be formed by chipping grooves by anisotropic etching. It can be highly accurate.

Further, in these inventions, claim 6
According to the described invention, when the flow path substrate is laminated and mounted on the heating element substrate, even if the flow path substrate is opaque, the flow path groove is formed on the surface opposite to the groove surface and visible from the outside. Since the recognizing means for recognizing the mounting direction such as the above is provided, it is possible to easily perform the laminated mounting on the heating element substrate.

On the other hand, according to the seventh aspect of the invention, since the position matching means is provided by the combination of the positioning pattern formed on the heating element substrate and the positioning see-through portion penetratingly formed on the flow path substrate, the flow path substrate is Even if it is opaque, the heat generating part and the groove for the flow path can be accurately aligned at the time of assembly, and since the positioning transparent part on the flow path substrate side is anisotropically etched, a separate step is not required. , Compared to the simple through-processing by laser processing,
The accuracy is extremely high, and highly accurate position alignment is possible.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, (a) is a perspective view of a head chip, and (b) is a partially enlarged front view thereof.

FIG. 2 is a perspective view showing a heating element substrate.

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 an exploded perspective view showing a modified example.

FIG. 8 is a front view showing the features of chipping processing.

FIG. 9 is a front view showing a modification thereof.

FIG. 10 is a plan view showing another modification.

FIG. 11 is a plan view showing a flow path substrate.

FIG. 12 is an exploded perspective view showing the features of the assembly process.

FIG. 13 is a plan view showing a part of the device in an enlarged manner.

FIG. 14 is a plan view showing a modification thereof.

15A and 15B show an embodiment with a trapezoidal groove, FIG. 15A is a perspective view of a head chip, and FIG. 15B is an enlarged front view of a part thereof.

FIG. 16 is a perspective view showing a crystal plane and a crystal axis direction of the channel substrate.

FIG. 17 is a vertical cross-sectional front view sequentially showing the anisotropic etching step for the flow path substrate.

FIG. 18 is an exploded perspective view showing a modification thereof.

[Explanation of symbols]

 2 heating element substrate 3 flow path substrate 4 recognition means 6 flow path groove 9,10 electrode 21 heat storage layer 22 heat generation layer 23 protective layer 30, 31 chip forming groove 32a, 32b recognition means 33 positioning pattern 34 positioning transparent portion 35 position alignment Means 36 Positioning see-through part

Claims (7)

[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 a single crystal substrate, and the same crystal orientation plane as that of the single crystal substrate. And a flow path substrate in which a flow path groove is formed by anisotropic etching on a single crystal substrate, the heating element substrate and the flow path substrate are aligned in the crystal axis direction, and the heat generation surface and the groove surface are opposed to each other. The thermal ink jet head is characterized in that an ink flow path opening is formed by cutting the stack in a direction substantially perpendicular to the flow path groove. 2. The single crystal substrates forming the heating element substrate and the flow path substrate are both single crystal silicon wafers cut out in the crystal orientation plane of the (100) plane, and <11 of both single crystal substrates.
The thermal ink jet head according to claim 1, wherein the thermal ink jet heads are laminated with the 0> axial direction aligned. 3. A single crystal substrate is a single crystal silicon wafer cut out in a crystal orientation plane of a (100) plane, and a groove for a flow path is V-shaped.
3. The thermal ink jet head according to claim 1, wherein the flow path substrate is formed into a groove and is formed into a chip by dicing two equivalent <110> axial directions of the silicon wafer which are orthogonal to each other. 4. A single crystal substrate is a single crystal silicon wafer cut in a crystal orientation plane of (100) plane, a channel groove is a trapezoidal groove, and two equivalent <110 perpendicular to the silicon wafer. A thermal ink jet head according to claim 1 or 2, wherein the flow path substrate is formed into chips by axial dicing. 5. The thermal ink jet head according to claim 1, wherein the channel substrate is made into chips by chipping grooves formed deeper than the channel grooves by anisotropic etching. 6. A flow channel substrate having a recognition means for recognizing the mounting direction with respect to the heating element substrate from the side opposite to the groove surface having the flow channel groove.
The thermal ink jet head described in 2, 3, 4 or 5. 7. A combination of a positioning pattern formed by photofabrication on a heating element substrate and a positioning see-through portion penetratingly formed by anisotropic etching at a position corresponding to the positioning pattern with respect to the flow path substrate. The thermal inkjet head according to claim 1, 2, 3, 4, or 5, further comprising: