JP2009148941A - Inkjet recording head and method for production of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording head and an inkjet recording head manufacturing process for achieving a membrane thickness optimal to a heater protection membrane and a membrane thickness required for an anisotropic etching stopping layer in a heater board process (adaptive to monolayer wiring) of a BTJ. <P>SOLUTION: A p-SiNx is deposited up to the membrane thickness required for the heater protection membrane, thereafter, a cavitation-resistant layer composed of Ta is formed on the heater, then, the p-SiNx is deposited again up to the membrane thickness required as a membrane. Next, the p-SiNx layer as the second layer is shaved using the Ta as an etching stopping layer, then, the heater protection membrane can obtain the required membrane thickness in respective membranes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet recording head that discharges a desired liquid by applying energy to the liquid from the outside, and a method for manufacturing the inkjet recording head.

  Regarding the ink jet recording head, the ink jet recording head described in Japanese Patent Application Laid-Open No. 54-51837 applies thermal energy to a liquid, and the liquid receiving the thermal energy is heated to generate bubbles, and the bubbles A droplet is ejected from the orifice at the tip of the recording head by an acting force based on the generation, and the droplet adheres to a recording member to record information.

  A recording head applied to this recording method generally includes an orifice provided for discharging a liquid, and a heat acting portion that is a portion where heat energy for discharging a droplet communicated with the orifice acts on the liquid. A liquid discharge section having a liquid flow path as a part of the structure, a heat generation resistance layer as a heat conversion body that is a means for generating thermal energy, a heater protection layer that protects it from ink, and a resistance to protection from cavitation It has a cavitation layer and a heat storage layer (lower layer) for storing heat.

  Japanese Patent Application Laid-Open No. 9-11479 proposes a method of forming an ink supply port by anisotropic etching. Further, a method for forming an ink supply port with high precision by anisotropic etching has been proposed in Japanese Patent Laid-Open No. 10-181032.

Briefly describing the process:
1) A silicon dioxide film is formed on the surface of a silicon substrate by thermal oxidation.
2) Next, a heating resistor is formed on the silicon dioxide film,
3) Remove the silicon dioxide film in place,
4) A poly-Si film was formed and formed on the portion from which the silicon dioxide was removed to form a sacrificial layer.
5) Further, a passivation layer made of a silicon nitride film is formed on the heating resistor and the buried sacrificial layer.
6) Thereafter, the flow path forming layer and the nozzle forming layer are formed by a post process,
7) Perform anisotropic etching of silicon from the back surface with TMAH,
8) The silicon dioxide film is removed, and the sacrificial layer is removed with TMAH.
9) The ink jet recording head is formed by removing the passivation film at the ink supply port by RIE.
JP 54-51837 A Japanese Patent Laid-Open No. 9-11479 Japanese Patent Laid-Open No. 10-181032

  Conventionally, in the method of forming an ink jet recording head in Japanese Patent Laid-Open No. 10-181032, a sacrificial layer is etched away by TMAH to form a membrane made of a part of a passivation layer made of a silicon nitride film. . Since the passivation layer and the membrane are formed and formed in the same process, the film thickness is the same.

  However, the film thickness of the protective film formed on the heating resistor is not limited to a thickness that is more than necessary, as long as the film thickness is sufficient to ensure reliability from the relationship of ink ejection efficiency. In order to ensure reliability, at least 250 nm is sufficient.

  On the other hand, in the process of forming the ink supply port by anisotropic etching, the thickness of the passivation layer to be a membrane needs to be 500 nm or more in order to reduce membrane cracking defects in the process. It is necessary to secure a film thickness of 1000 nm or more.

  If priority is given to improving ink ejection efficiency, the membrane (passivation layer) will be thin, and the membrane will crack during anisotropic etching, resulting in poor yields. In order to prevent the membrane from cracking, increasing the thickness of the passivation layer will degrade the ink ejection efficiency compared to the power consumption of the heating resistor, and hinder the speeding up of the drive. There was a problem.

  FIG. 9 is a diagram showing a manufacturing process flow of an ink jet recording head according to a conventional example.

In order to solve the above problems, in the present invention, a heater protective film for protecting a plurality of heat generating resistors for discharging ink is formed, and further, a heat generating resistor having a cavitation-resistant film is provided, and etching is performed. In the inkjet recording head substrate forming the ink supply port, the heater protective film and the etching stop layer are made of the same material, and the thickness of the heater protective film is made thinner than the thickness of the etching stop layer, Since it is possible to set the optimum film thickness as the heater protection film and the optimum film thickness as the etching stop layer,
The problem is that the etching stop layer is thin and the membrane is cracked during anisotropic etching, resulting in poor yield, and the protective film formed on the heating resistor is thick, resulting in poor ink ejection efficiency. The problem can be solved.

  In the method of manufacturing an ink jet recording head of the present invention, the second etching stop layer formed on the upper layer portion of Ta, which is a cavitation resistant film formed on the heater, is removed by dry etching. By using as a dry etching stop layer, the second etching stop layer can be selectively removed.

By this step, it is possible to set an optimum film thickness as a heater protective film and an optimum film thickness as an etching stop layer.
"Experiment"
[Experiment 1]
Dependence of deposition conditions on silicon nitride film (p-SiNx) by plasma CVD as an etching stop layer and stress, alkali resistance, and BHF resistance Dependence on deposition conditions of silicon nitride film (p-SiNx) by plasma CVD And the relationship between stress, alkali resistance, and BHF resistance were investigated.

  The film stress was measured by changing the composition to a silicon wafer having a substrate surface orientation (100) of 5 inches Φ and a thickness of 625 μm with a film thickness of 5000 mm, measuring the film deformation using a ZYGO interference displacement meter, and measuring the stress. Calculated.

  In addition, the alkali resistance was determined by forming a film having a thickness of 5000 mm on a silicon wafer and changing the composition, immersing the film in a 20% aqueous TMAH solution (an etchant temperature of 83 ° C.), and measuring the etching rate.

  The etching rate of Si with a substrate orientation of 100 was 30 to 50 μm / hr.

For the BHF resistance, a sample similar to the alkali resistance test sample was prepared and immersed in BHF to measure the etching rate. BHF used was Daikin Industries BHF63U. HF: 6 mass%, NH ₄ F 30.1 mass%, and the remaining H ₂ O.

The etching rate of the thermally oxidized SiO ₂ film with BHF used in this experiment was 900 to 1000 Å / min.

  In the process, it is necessary that the etching rate of TMAH is 500 以下 / hr or less and the etching rate of BHF is 200 Å / min or less.

The silicon nitride film formed by plasma CVD uses SiH ₄ / NH ₃ / N ₂ as a source gas, SiH ₄ is 200 sccm, N ₂ is 2000 sccm, the substrate temperature is 300 ° C., the pressure is 1500 mTorr, and the NH ₃ gas flow rate is fixed. The film stress of p-SiNx was changed using RF power as a parameter.

(Table 1-1 shows the relationship between NH ₃ gas flow rate, stress, and etching rate at RF power of 1500 W.)
(Tables 1-2, 1-3, and 1-4 show the relationship between NH ₃ gas flow rate, stress, and etching rate at RF powers of 1000 W, 750 W, and 500 W.)
1) Although the film stress of the p-SiNx film deposited with RF power of 1500 W changes from compression to tension as the NH ₃ flow rate increases, the etching rates of TMAH and BHF also increase rapidly. The film stress of p-SiNx having a TMAH etching rate of 500 Å / hr or less and a BHF etching rate of 200 Å / min or less is −5 × 10 ⁹ dyne / cm ² or more of compression.

  2) Tables 1-2, 1-3, and 1-4 show the results of similar experiments with different RF powers.

It was possible to obtain a silicon nitride film by plasma CVD satisfying the required specifications of film stress, TMAH, and BHF etching rate in the low RF power and low NH3 flow rate region. (No. 2 in Table 1-2, No. 1 and No. 2 in Table 1-3, No. 1 in Table 1-4)
Therefore, it was found that a silicon nitride film (p-SiNx) satisfying the required specifications of the TMAH and BHF etching rates can be obtained with low film stress by controlling the film formation parameters of plasma CVD.

Table 1-1 (RF power 1500W)
SiH ₄ (200sccm), N ₂ (2000sccm), Press_1.5Torr, RFpower_1500w
No NH ₃ film stress TMAH etching rate BHF etching rate
Sccm dyne / cm ² Å / hr Å / min
1 0 -9 × 10 ⁹ 95 80
2 100 -8 × 10 ⁹ 110 160
3 300 -5 × 10 ⁹ 140 530
4 500 -2 × 10 ⁹ 150 650
5 700 -2 × 10 ⁹ 220 1000
6 1000 -0.5 × 10 ⁹ 300 1500
7 1200 + 2 × 10 ⁹ 650 3000
8 1500 + 5 × 10 ⁹ 1000 5000
Table 1-2 (RF power 1000W)
SiH ₄ (200sccm), N ₂ (2000sccm), Press_1.5Torr, RFpower_1000w
No NH ₃ film stress TMAH etching rate BHF etching rate
Sccm dyne / cm ² Å / hr Å / min
1 0 -5 × 10 ⁹ 120 80
2 50 -3 × 10 ⁹ 120 100
3 100 -2 × 10 ⁹ 130 190
4 300 + 3 × 10 ⁹ 190 1400
5 500 + 4 × 10 ⁹ 230 3100
Table 1-3 (RF power 750W)
SiH ₄ (200sccm), N ₂ (2000sccm), Press_1.5Torr, RFpower_500w
No NH ₃ film stress TMAH etching rate BHF etching rate
Sccm dyne / cm ² Å / hr Å / min
1 0 -1 × 10 ⁹ 125 105
2 50 + 3 × 10 ⁹ 130 190
3 100 + 4 × 10 ⁹ 250 220
4 300 + 7 × 10 ⁹ 720 5200
Table 1-4 (RF power 500W)
SiH ₄ (200sccm), N ₂ (2000sccm), Press_1.5Torr, RFpower_500w
No NH ₃ film stress TMAH etching rate BHF etching rate
Sccm dyne / cm ² Å / hr Å / min
1 0 + 1 × 10 ⁹ 150 100
2 50 + 3 × 10 ⁹ 200 300
3 100 + 5 × 10 ⁹ 450 920
4 300 + 7 × 10 ⁹ 720 7200
[Experiment 2]
FIG. 1B is a schematic cross-sectional view of an element in the middle of the manufacturing process of the ink jet recording head according to the present invention. FIG. 1C shows a case where a hole is drilled from the lower part of the Si substrate by anisotropic etching. Etching removes up to the sacrificial layer 103. The etchant for anisotropic etching is blocked by the etching stop layer 106, and the nozzle portion and the flow path forming material made of the upper resin are protected from the etchant. What is required for this etching stop layer is etchant resistance and strength as a membrane. Therefore, a sample was prepared by laminating 6000 mm of p-SiNx as an etching stop layer, and after anisotropic etching of the Si substrate, it was observed with a microscope whether the upper resin layer or the like was damaged by the intrusion of the etchant. .

The results are shown in Table 2. It was found that when the film stress is a compressive stress of −3 × 10 ⁻⁹ dyne / cm ² or more and a tensile stress of 3 × 10 ⁻⁹ dyne / cm ² or more, the etching stop layer may be broken.

That is, it was found that the etching stop layer was not cracked when the film stress was in the range of −3 × 10 ⁻⁹ dyne / cm ² to 3 × 10 ⁻⁹ dyne / cm ² .
Table 2
No Film stress of laminated film Breakage 1-5 x 10 ⁹ dyne / cm ² 100% Break 2-4 x 10 ⁹ dyne / cm ² 50% Break 3-3 x 10 ⁹ dyne / cm ² 0% Breaking 4 -0.5 × 10 ⁹ dyne / cm ² 0% Breaking 5 +3 × 10 ⁹ dyne / cm ² 0% Breaking 6 +4 × 10 ⁹ dyne / cm ² 30% Breaking 7 +5 × 109 dyne / cm ² 100% tearing [Experiment 3]
Using the # 3-5 p-SiNx film in which the tear in Experiment 2 did not occur, the film thickness was changed from 1000 to 2 μm, and the same evaluation as in Experiment 2 was performed. As a result, it was found that when the film thickness was 2000 mm, partial cracking occurred, and when the film thickness was 5000 mm or more, the etching layer did not break.
Table 3
Film thickness Crack occurrence
1000% 100%
2000% 20%
3000% 10%
5000kg 0%
6000Å 0%
8000Å 0%
10000Å 0%
20,000Å 0%
30000cm 0%
[Experiment 4]
Stress of Laminated Silicon Nitride Film A No. 3 (NH ₃ 100 sccm, RF power 1000 W, film stress −2 × 10 ⁹ dyne / cm ² ) film shown in Table 1-2 of Experiment 1 is used as the first silicon nitride film. Silicon nitride having a film stress of + 3 × 10 ⁹ dyne / cm ² was laminated as the silicon nitride film of the layer, and the film stress as the laminated film was measured.
No 1-layer film stress / thickness 2-layer film stress / thickness laminate film of the stress / thickness ^{1 -2E9dyne / cm 2, 3000Å +} 3E9dyne / cm 2, 3000Å + 0.6E9dyne / cm 2, 6000Å
^{2 -2E9dyne / cm 2, 3000Å +} 3E9dyne / cm 2, 5000Å + 1E9dyne / cm 2, 8000Å
^{3 -2E9dyne / cm 2, 2000Å +} 3E9dyne / cm 2, 4000Å + 1.5E9dyne / cm 2, 6000Å
As the first silicon nitride film, the No. 1 (NH ₃ 0 sccm, RF power 1000 W, film stress -5 × 10 ⁹ dyne / cm ² ) film in Table 1-2 of Experiment 1 was used, and the second silicon nitride film As the film stress, silicon nitride having a film stress of + 3 × 10 ⁹ dyne / cm ² and + 5 × 10 ⁹ dyne / cm ² was laminated, and the film stress as the laminated film was measured.

In the case of the laminated structure, even if the stress of the first silicon nitride film is large, the stress is controlled by the second silicon nitride film, and the film stress is reduced from the compressed film of −3 × 10 ⁹ dyne / cm ² as the laminated film. It is controlled to + 3 × 10 ⁹ dyne / cm ² .
No 1-layer film stress / thickness 2-layer film stress / thickness laminate film of the stress / thickness ^{1 -5E9dyne / cm 2, 3000Å +} 3E9dyne / cm 2, 7000Å + 0.6E9dyne / cm 2, 10000Å
^{2 -5E9dyne / cm 2, 3000Å +} 3E9dyne / cm 2, 9000Å + 1E9dyne / cm 2, 12000Å
^{3 -5E9dyne / cm 2, 3000Å +} 5E9dyne / cm 2, 5000Å + 1.25E9dyne / cm 2, 8000Å
Therefore, it was found that the film stress can be controlled as a laminated film.
[Experiment 5]
The film stress of the silicon nitride film by plasma CVD and the substrate temperature dependence of BHF resistance were investigated.

Plasma silicon nitride deposition conditions 1)
As the raw material gas, a _{SiH 4 / NH 3 / N 2} , the flow rate was _{SiH 4 / 200sccm, NH 3 /} 500sccm, N2 / 2000sccm, pressure 1500 mTorr, and RF power 1500 W, varying the substrate temperature from 200 ° C. to 500 ° C. Then, p-SiNx was deposited, and the film stress and the BHF etching rate were measured.
Table 5-1 Substrate temperature and film stress, BHF etching rate 1
_{SiH 4 (200sccm), NH 3} (500sccm), N 2 (2000sccm), Press_1.5Torr, RFpower_1500w
No Substrate temperature Film stress BHF etching rate ℃ dyne / cm ² Å / min
1 200 -1 × 10 ⁹ 8000
2 300 -2 × 10 ⁹ 650
3 400 -3 × 10 ⁹ 250
4 500 -4 × 10 ⁹ 100
Plasma silicon nitride deposition conditions 2)
As the raw material gas, a SiH ₄ / N _2, the flow rate of _{SiH 4 / 200sccm, N 2 /} 2000sccm, pressure 1500 mTorr, and RF power 1000W, depositing a p-SiNx by changing the substrate temperature from 200 ° C. to 500 ° C. The film stress and BHF etching rate were measured.
Table 5-2 Substrate temperature and film stress, BHF etching rate 1
SiH ₄ (200sccm), N ₂ (2000sccm), Press_1.5Torr, RFpower_1000w
No Substrate temperature Film stress BHF etching rate
℃ dyne / cm ² Å / min
1 200 -3 × 10 ⁹ 190
2 300 -5 × 10 ⁹ 80
3 400 -6 × 10 ⁹ 60
4 500 -7 x 10 ⁹ 50
As described above, by changing the deposition conditions of plasma silicon nitride, p-SiNx having film stress and BHF resistance satisfying required specifications could be obtained at a substrate temperature of 200 ° C. to 500 ° C.

In particular, even if the substrate temperature is lowered in a low NH ₃ flow rate region (including 0 sccm), the film stress can be controlled without increasing the BHF etching rate.
[Experiment 6]
When the silicon nitride film formed by plasma CVD was used as a heater protective film, the film thickness, the energy applied to the heater, and the efficiency of ink discharge were examined.

  Table 6 shows the relationship between the heater protective film thickness and the discharge start energy.

  The relationship between the film thickness of the heater protective film and the success or failure of the discharge is clear. When the p-SiNx film thickness is 5000 mm or more, the ink discharge is unstable, and the energy input to the heater is large. When the current is turned on, the heater breaks.

Therefore, the film thickness as the heater protective film needs to be 4000 mm or less.
Table 6 Relationship between heater protective film thickness and discharge start energy No p-SiNx film thickness Ink discharge 1 1000 OK
2 2000 OK
3 3000 OK
4 4000 OK
5 5000 NG
6 7000 NG
7 10000 NG
[Experiment 7]
The etching rate was examined by RIE using a plasma silicon nitride film (p-SiNx) and a cavitation-resistant Ta SF ₆ or O ₂ gas.

Table 7 shows the O ₂ concentration and the etching rates of p-SiNx and Ta.

The etching rate of Ta is drastically decreased by adding O _2, and the ratio of the etching rate of p-SiNx, that is, the selectivity is remarkably improved. By adding 10% or more, the selection ratio becomes 20 or more, and p-SiNx can be etched using Ta as an etching stop layer.
Table 7
No O ₂ addition concentration p-SiNx Ta selectivity 10% 1200% 1100% 1.1
2 5% 1100 Å 200 ５ 5.5
3 10% 1000 Å 50 ２０ 20
4 20% 900 Å 10 ９０ 90
5 30% 800 Å 10 ８０ 80
6 50% 600 Å 10 ６０ 60

The ink jet recording head of the present invention has the following effects by taking the configuration described above.
1) High reliability and high yield were achieved.
2) Since the heater protective film can be made thinner, the power use efficiency with respect to ink ejection is improved, so that power consumption is reduced and the life of the ink jet recording head is extended.
3) Since the stop layer at the time of the anisotropic etching can be formed sufficiently thick regardless of the thickness of the heater protective film, the yield at the time of anisotropic etching is improved, and a high-yield inkjet recording head can be manufactured.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  Hereinafter, another method for manufacturing the ink jet recording head according to the present invention will be described in order.

  FIG. 1A is a schematic view of a base substrate of an ink jet recording head showing an embodiment according to the present invention. As the substrate, a silicon wafer having a substrate surface orientation of (100) or (110) is used. A through-hole 115 for supplying ink from the back surface is formed in the center of the substrate.

  FIG. 1B shows a method of manufacturing an ink jet recording head according to the present invention, in which a heater 104 and a wiring electrode 103 for heating an ink are formed on a base substrate, and silicon nitride (p-SiN) is formed by plasma CVD as an etching stop layer (110). ) Is a schematic diagram of a cross section of the deposited layer. FIG. 1C is a cross-sectional view of an ink jet recording nozzle formed of resin or the like on a base substrate, and an ink flow path 115 formed on the Si substrate from the opposite side of the nozzle to the etching stop layer by anisotropic etching. .

  Next, the process of the ink jet recording nozzle according to the present invention will be described with reference to FIGS.

A silicon (Si) substrate 101 having a thickness of 625 μm and a substrate surface orientation (110) or (100) of 5 inches Φ (which will be described using the substrate orientation (100) substrate in this sectional view) is thermally oxidized as an insulating film. The thermal oxide film (SiO ₂ ) 102 was formed in 20000 mm (FIG. 2A), and the thermal oxide film in the supply port opening (the part where the etching stop layer is formed) was removed using photolithography. (Fig. 2-b)
In this embodiment, a description will be given using a 5-inch Φ silicon substrate, but the wafer shape and size are not limited, and a square or rectangular silicon substrate may be used, and the size is not limited.

As the insulating film, silicon nitride (SiN) or the like may be used in addition to the thermal oxide film (SiO ₂ ). Further, the production method is not limited to the thermal oxidation method, but may be an LPCVD method or an atmospheric pressure CVD method.

  A sacrificial layer 103 was formed by depositing 2000 liters of AlCu film by sputtering and patterning it as shown in FIG. The width of the sacrificial layer was 120 μm, and the long side direction was 15 mm.

  When the etching progresses from the back surface and the etchant reaches the sacrificial layer, the sacrificial layer is etched in a short time because the etching rate is much faster than that of the silicon wafer, and an opening corresponding to the sacrificial layer pattern can be opened. is there.

  In this embodiment, AlCu is used as the sacrificial layer. However, an alloy of Al, Cu, and Si, amorphous silicon by plasma CVD, polycrystalline silicon, porous silicon by anodization, and silicon dioxide obtained by oxidizing porous silicon. Etc. may be used.

  Next, by sputtering, a film of TaSiN of 500 mm and AlCu of 2500 mm was continuously formed, followed by patterning to form a heater portion 104 and an electrode 105 as ink discharge pressure generating elements (FIG. 2D).

As the heater material, in addition to TaSiN, a metal film such as Ta, TaN, HfB ₂ or the like may be deposited by sputtering, vacuum evaporation, or the like. Further, a metal film such as Mo or Ni may be formed in the same manner as the electrode 105 for power supply in addition to AlCu.

  Further, the thermal oxide film 102 has 20000 mm between the heater and the electrode and the silicon wafer, and functions as a heat storage layer.

  Next, for the purpose of improving the durability of the heater, 3000 nm of silicon nitride film was deposited by plasma CVD to form the heater protective film 106 (FIG. 3-a). This silicon nitride film functions not only as a heater protective film but also as a first etching stop layer 106A when forming the ink supply port.

  Since the silicon nitride film formed so as to cover the sacrificial layer functions as a stop layer when the silicon substrate is anisotropically etched by TMAH or the like as described later, it is described as an etching stop layer.

  The thickness of the heater protective layer is 1500 to 4000 mm, more preferably 2500 to 3500 mm.

Further, the film stress of the plasma CVD silicon nitride film as the heater protective layer and the first etching stop layer is more preferably from compressive stress −5 × 10 ⁹ dyne / cm ² to tensile stress + 3 × 10 ⁹ dyne / cm ^2. Is from a compressive stress of -5 × 10 ⁹ dyne / cm ² to a tensile stress of + 1 × 10 ⁹ dyne / cm ² , and optimally from a compressive stress of −3 × 10 ⁹ dyne / cm ² to a compressive stress of −1 × 10 ⁹ dyne. / Cm ² .

  In addition, a silicon nitride film having a film stress within the above range, an etching rate of TMAH (22%, 83 ° C.) of 500 Å / hr or less, and an etching rate of BHF of 200 Å / min or less is formed by plasma CVD. did.

  The conditions for forming a silicon nitride film by plasma CVD in this embodiment will be described.

SiH ₄ , NH ₃ , and N ₂ were used as source gases, the flow rates were 200, 100, and 2000 sccm, the discharge pressure was 1.5 Torr, the RF power was 1000 W, and the deposition temperature was 300 ° C.

The film stress of silicon nitride was compression −2 × 10 ⁹ dyne / cm ² , the etching rate of TMAH (22%, 83 ° C.) was 130） / hr, and the etching rate of BHF was 190 Å / min.

  In this embodiment, an example of the film formation condition of silicon nitride by plasma CVD is shown. However, if the film stress, the etching rate of TMAH (22%, 83 ° C.), and the etching rate of BHF satisfy the conditions described above. It ’s fine. Examples of other specific film forming conditions for the etching stop layer are described in the above-mentioned experimental items.

Furthermore, the deposition temperature is preferably 250-450 ° C, optimally 300-350 ° C. Further, the source gas of the silicon nitride film by plasma CVD is not limited to the combination of SiH ₄ , NH ₃ , and N ₂ described in this embodiment, but a combination of SiH ₄ , NH ₃ , N ₂ , and H ₂ . (SiH ₄ / NH ₃ / N ₂ / H ₂ , SiH ₄ / NH ₃ / N ₂ , SiH ₄ / NH ₃ / H ₂ , SiH ₄ / N ₂ , SiH ₄ / H ₂ / N ₂ , SiH ₄ / NH ₃ ) may be used.

  Next, Ta was formed into a film by sputtering, and the anti-cavitation film 107 was formed. Subsequently, patterning was performed by the photolithography technique so as to remain in the heater portion and the vicinity thereof as shown in FIG.

Next, 10,000 nm of silicon nitride film 108 was deposited by plasma CVD to form a second etching stop layer. (Fig. 3-c)
The film thickness of the second etching stop layer is from 2000 to 30000 mm, more preferably from 5000 to 17000 mm.

  The film thickness of the etching stop layer is a laminated film thickness of the first etching stop layer and the second etching stop layer, which is 13000 mm.

The film stress of the second etching stop layer is from compressive stress −3 × 10 ⁹ dyne / cm ² to tensile stress + 5 × 10 ⁹ dyne / cm ² , more preferably compressive stress −2 × 10 ⁹ dyne / cm 2. ^{From 2} to tensile stress + 2 × 10 ⁹ dyne / cm ² , optimally from compressive stress −1 × 10 ⁹ dyne / cm ² to tensile stress + 1 × 10 ⁹ dyne / cm ² .

The film stress of the etching stop layer is a compressive stress of −3 × 10 ⁹ dyne / cm ² to a tensile stress + 3 × 10 ⁹ dyne / cm ² as a total value of the two layers. Therefore, when the first layer is a compressive film with a strong etching stop, the total value of the film stresses of the two layers may be within the above range with the second etching stop layer as a tensile stress film.

Subsequently, patterning is performed so as to remove the second etching stop layer on the heater portion by photolithography technique and dry etching technique, and the second etching stop layer is removed 109 by etching. (Fig. 3-d)
For example, when an RIE (Reactive Ion Etching) apparatus is used, SF6 200 sccm and O ₂ 40 sccm are introduced as etching gases, and etching is performed at a gas pressure of 30 mTorr RF power of 800 W, p-SiNx corresponding to the etching rate of Ta (tantalum) is obtained. The etching rate ratio, so-called selection ratio, can be set to 90, and Ta of the anti-cavitation layer 107 can be used as an RIE / etching stop layer during RIE to remove the second p-SiNx layer.

In this embodiment, SF ₆ / O ₂ is used as an etching gas, but CHF ₃ / O ₂ gas may be used.

Next, the thermal oxide film 102 on the back surface of the silicon substrate was removed using a photolithographic technique, the wafer surface was exposed, and the ink supply portion 110 on the back surface was formed, whereby the heater board was completed. (Fig. 4-a)
Next, 20 μm of polymethylisopropenyl ketone (Tokyo Ohka ODUR-1010) as a photosensitive resin was applied and patterned to form an ink flow path mold 111. Further, as shown in FIG. 4B, the photosensitive resin layer 112 was applied by 10 μm and patterned to form the ink discharge port 113.

The photosensitive resin is 1) Epoxy resin (o-cresol type epoxy resin)
Yuka Shell Epicoat 180H65) 100 parts 2) Photocationic polymerization initiator (44 'di-butylphenyl iodonium)
Hexafluoroantimonate) 1 part 3) Silane coupling agent 10 parts by Nippon Unicar A187

In order to protect the nozzle forming surface side, a protective film 114 was formed with a rubber resist (OBC manufactured by Tokyo Ohka Kogyo Co., Ltd.). (Fig. 4-b)
This substrate was immersed in 20% TMAH aqueous solution and anisotropically etched. The etchant temperature was 83 ° C. and the etching time was 12 hours. This was an overetching time of 10% with respect to the time for just etching the thickness of the substrate of 625 μm.

  In this embodiment, TMAH is used as the anisotropic etching solution, but an etching solution such as an aqueous potassium hydroxide solution, EDP, or hydrazine may be used.

  Etching proceeds as shown in FIG. 4C, and stops in front of the first etching stop layer 106A. At this time, there was no crack in the etching stop layer, and no penetration of the etching solution into the flow path forming resin layer 111 and the nozzle portion 112 was observed.

The burrs of the thermal oxide film on the back surface of the silicon substrate were removed by etching with BHF (FIG. 5-a), and then the p-SiN as the etching stop layers 106A and 108 were removed by RIE. The etching conditions were SF ₆ / O ₂ 200/40 sccm RF 800 W, pressure 20 mTorr. Next, after being immersed in methyl isobutyl ketone, the protective film 114 was removed by applying ultrasonic waves in xylene.

Furthermore, the resin 111 was removed by applying ultrasonic waves in methyl lactate to form the ink flow path 115, and an ink jet recording head was completed. (Fig. 5-b)
In the case of this embodiment, the anisotropic etching stop layer is sufficiently thick so as not to cause cracks, and the heater protective film does not need to be thicker than necessary, so that a high-yield inkjet recording head can be manufactured. It was. In addition, since the electric power supplied to the heater is no longer necessary, the life of the heater is extended and the reliability is improved.

  Further, a printing test was performed using this ink jet recording head at an ejection frequency of 10 KHz. A high-quality printed matter free from printing blur, density unevenness, and non-ejection of ink was obtained over the entire 15 mm width.

  In the following, another embodiment of the present invention will be described.

On the Si wafer 201 having a thickness of 625 μm and a substrate orientation (110) plane of 5 inches Φ, thermal oxidation was performed to form 14000 mm of SiO ₂ layer 102. Next, SiO ₂ was patterned to form a supply port opening. 2000 liters of AlCu alloy film was deposited with a sputter. A sacrificial layer 103 was formed by patterning as shown in FIG. The width of the sacrificial layer was 120 μm, and the long side direction was 15 mm.

  As for the planar shape of the sacrificial layer, when a plane orientation (100) substrate of a silicon wafer is used, the pattern is arranged in a rectangle as shown in FIG. When using the substrate plane orientation (110) substrate, the pattern is a parallelogram with a narrow angle of 70.5 degrees as shown in FIG. The long side and the short side of the parallelogram are arranged so as to be parallel to a plane equivalent to (111).

  Next, by sputtering, 500 nm of TaSiN and 2000 mm of AlCu were continuously formed, followed by patterning to form a heater portion 104 and an electrode 105 as ink discharge pressure generating elements.

  Next, for the purpose of improving the durability of the heater, 2500 nm of silicon nitride film was deposited by plasma CVD to form the heater protective film 106 and the first etching stop layer 106A (FIG. 7B). This silicon nitride film functions not only as a heater protective film but also as a first etching stop layer 106A when forming the ink supply port.

The plasma CVD silicon nitride formed as the heater protection film 106 and the first etching stop layer 106A in this embodiment has a film stress of -5 × 10 ⁹ dyne / cm ² , an etching rate of TMAH of 120 Å / hr, and an etching of BHF. A film having a rate of 80 kg / min was used.

The silicon nitride film was formed by plasma CVD using SiH ₄ and N ₂ as source gases, flow rates of 200 and 2000 sccm, discharge pressure of 1.5 Torr, RF power of 1000 W, and deposition temperature of 300 ° C., respectively.

The film stress as the heater protective film and the first etching stop layer is from compressive stress −5 × 10 ⁹ dyne / cm ² to tensile stress + 3 × 10 ⁹ dyne / cm ² , more preferably compressive stress −5 × 10 6. ^{From 9} dyne / cm ² to tensile stress + 2 × 10 ⁹ dyne / cm ² , optimally from compressive stress −5 × 10 ⁹ dyne / cm ² to −1 × 10 ⁹ dyne / cm ² .

  Next, Ta was formed into a film by sputtering, and the anti-cavitation film 107 was formed. Subsequently, patterning was performed so as to leave the heater portion 104 and the vicinity thereof by photolithography.

Next, 17500 窒 化 of silicon nitride film was deposited by plasma CVD to form a second etching stop layer 108. (Fig. 7-c)
A tensile stress film was used as the plasma silicon nitride film formed in this example. A film having a film stress of + 3 × 10 ⁹ yne / cm ² was used.

The film stress as a laminated film of the first etching stop layer and the second etching stop layer was a tensile stress of + 2 × 10 ⁹ dyne / cm ² .

The film stress of the etching stop layer may be a compressive stress of −3 × 10 ⁹ dyne / cm ² to a tensile stress + 3 × 10 ⁹ dyne / cm ² as a total value of the two layers. Accordingly, when the first layer etching stop is a strong compression film, the total value of the two layers of film stress may be within the above range with the second etching stop layer as a tensile stress film.

Subsequently, patterning is performed so as to remove the second etching stop layer 108 on the heater portion by a photolithography technique and a dry etching technique, and the second etching stop layer 108 is removed by etching. (Fig. 7-d)
For example, SF ₆ or O ₂ gas is used as an etching gas, and Ta of the anti-cavitation layer 310 is used as an RIE / etching stop layer during RIE to remove the second layer of p-SiNx.

  Next, the thermal oxide film 102 on the back surface of the silicon substrate was removed using a photolithographic technique, the wafer surface was exposed, and the ink supply portion 110 on the back surface was formed, whereby the heater board was completed.

  Next, in the same manner as in Example 1, an ink flow path mold material 111 was formed, and a photosensitive resin layer was applied and patterned to form an ink discharge port 113.

In order to protect the nozzle forming surface side, a protective film 114 was formed with a rubber resist. (Fig. 8-a)
Next, a non-penetrating etching lead hole 202 was opened with a YAG laser as shown in FIG. 8B in the narrow-angle portion of the parallelogram window of the ink supply port pattern portion on the back surface. At this time, the diameter of the hole was 30 to 35 μm, and the depth was 550 to 600 μm.

  This substrate was immersed in 20% TMAH aqueous solution and anisotropically etched. The etchant temperature was 83 ° C. and the etching time was 8 hours. This was an overetching time of 10% with respect to the time for just etching the thickness of the substrate of 625 μm.

Etching proceeds as shown in FIG. 8C and stops in front of the etching stop layer 106A. At this time, there was no crack in the etching stop layer, and no intrusion of the etching solution into the flow path forming resin layer 111 or the nozzle portion 112 was observed. In this example, the anisotropic etching stop layer was not cracked. In addition, since it is not necessary to make the heater protective film thicker than necessary, a high-yield inkjet recording head can be manufactured. In addition, since the electric power supplied to the heater is no longer necessary, the life of the heater is extended and the reliability is improved.

  Further, a printing test was performed using this ink jet recording head at an ejection frequency of 10 KHz. A high-quality printed matter free from printing blur, density unevenness, and non-ejection of ink was obtained over the entire 15 mm width.

(A) The schematic which shows the board | substrate of the inkjet recording head by this invention, (b, c) The outline which shows the board | substrate cross section in the middle of the manufacturing process of the inkjet recording head by this invention. (Ad) The figure which shows the manufacturing-process flow of the inkjet recording head by this invention (Example 1). (Ad) The figure which shows the manufacturing-process flow of the inkjet recording head by this invention (Example 1). (Ac) The figure which shows the manufacturing process flow of the inkjet recording head by this invention (Example 1). (Ab) The figure which shows the manufacturing-process flow of the inkjet recording head by this invention (Example 1). (A, b) The top view explaining the sacrificial layer shape of the inkjet recording head of this invention. (Ad) The figure which shows the manufacturing-process flow of the inkjet recording head by this invention (Example 2). (Ac) The figure which shows the manufacturing-process flow of the inkjet recording head by this invention (Example 2). (Ad) The figure which shows the manufacturing process flow of the inkjet recording head by a prior art example.

Explanation of symbols

101 Silicon substrate 102 Insulating film, thermal oxide film (SiO ₂ )
103 Sacrificial layer (AlCu)
104 Heater (TaSiN)
105 Electrode (AlCu)
106 heater protective film, first etching stop layer (p-SiNx)
106A First etching stop layer (p-SiNx)
107 Anti-cavitation film (Ta)
108 Second etching stop layer (p-SiNx)
109 removed etching stop layer portion 110 back ink supply portion 111 ink flow path mold material 112 photosensitive resin layer 113 ink discharge port 114 protective film 115 ink flow channel 201 silicon substrate 202 leading hole 301 sacrificial layer shape 302 sacrificial layer shape 500 Silicon substrate 501 Silicon dioxide 503 Heating resistor 504 Channel forming layer 505 Nozzle forming layer 506 Ejection port 507 Channel 509 Ink supply port 511 Sacrificial layer 516 Opening

Claims (15)

A heater protective film for protecting a plurality of heat generating resistors for discharging ink is formed. The heater protective film includes a heat generating resistor formed with an anti-cavitation film on the heater protective film, and the size of the ink supply port is defined by etching. In an ink jet recording head comprising an ink jet recording head substrate in which a sacrificial layer is formed, an etching stop layer is further formed on the sacrificial layer, and an ink supply port is formed by etching.
An ink jet recording head, wherein the heater protective film and the etching stop layer are made of the same material, and the thickness of the heater protective film is smaller than that of the etching stop layer.   2. The ink jet recording head according to claim 1, wherein the etching stop layer is composed of two or more laminated films, and the first etching stop layer is the same as the heater protective film.   3. The ink jet recording head according to claim 1, wherein the heater protective film and the etching stop layer are a silicon nitride film formed by plasma CVD.   The inkjet recording head according to any one of claims 1 to 3, wherein the heater protective film has a thickness of 150 nm to 400 nm and the etching stop layer has a thickness of 500 nm or more. For said first silicon nitride film as an etching stop layer formed by plasma CVD is a membrane stress tensile from the compression ^{-5 × 10 9 dyne / cm 2} + 3 × 109dyne / cm 2, and an alkali etching solution The etching rate is 1/1000 or less of the etching rate of the Si wafer having the substrate orientation (100) plane, and the etching rate for BHF is 1/5 or less of the etching rate of thermally oxidized SiO _2. The inkjet recording head in any one of Claims 1-4. The film stress as an etching stop layer as a laminated film formed by the plasma CVD is from compression-3 × 10 ⁹ dyne / cm ² to tension + 3 × 10 ⁹ dyne / cm ² . The ink jet recording head according to claim 5.   7. The sacrificial layer is made of Al, AlCu alloy, amorphous silicon by plasma CVD, polycrystalline silicon, porous silicon by anodization, or silicon dioxide obtained by oxidizing porous silicon. The ink jet recording head according to any one of the above. A heater protective film for protecting a plurality of heat generating resistors for discharging ink is formed. The heater protective film includes a heat generating resistor formed with an anti-cavitation film on the heater protective film, and the size of the ink supply port is defined by etching. In the manufacturing method of the ink jet recording head, the sacrificial layer is formed, the etching stop layer is further formed on the sacrificial layer, and the ink jet recording head substrate includes the ink supply port formed by etching.
1) forming a silicon oxide film or a silicon nitride film on a silicon substrate;
2) a step of removing the silicon oxide film or the silicon nitride film in a portion where the ink supply port is formed;
3) forming a sacrificial layer in a portion where the silicon oxide film or silicon nitride film is removed;
4) forming an ink discharge pressure generating element on the silicon oxide film or silicon nitride film on the silicon substrate;
5) forming a heater protective film and a first etching stop layer on the ink discharge pressure generating element and the sacrificial layer;
6) a step of forming an anti-cavitation film thereon, a step of forming a pattern so as to leave the anti-cavitation film on at least the heat generating region of the ink discharge pressure generating element,
7) forming a second etching stop layer on the anti-cavitation film and the first etching stop layer;
8) A method for manufacturing an ink jet recording head, comprising a step of removing at least a second etching stop layer on the heat generating portion region by etching using an anti-cavitation film as an etching stop layer.   9. The method of manufacturing an ink jet recording head according to claim 8, wherein the heater protective film and the etching stop layer are a silicon nitride film formed by plasma CVD. In the step of removing at least the second silicon nitride film on the heat generating portion region by etching using the anti-cavitation film as an etching stop layer, etching is performed using a mixed gas of SF ₆ and O ₂ or a mixed gas of CHF ₃ and O _2. 10. The method of manufacturing an ink jet recording head according to claim 8, wherein the etching is performed by dry etching when the O ₂ mixing ratio is in the range of 10% to 50%. The silicon nitride film as the first etching stop layer by the plasma CVD has a film stress of compression −5 × 10 ⁹ dyne / cm ² to tension + 3 × 10 ⁹ dyne / cm ² and etching with respect to an alkaline etching solution. The rate is 1/1000 or less of the etching rate of the Si wafer on the substrate orientation (100) plane, and the etching rate for BHF is 1/5 or less of the etching rate of thermally oxidized SiO _2. Item 11. A method for manufacturing an ink jet recording head according to any one of Items 8 to 10. 9. The film stress as an etching stop layer as a laminated film formed by the plasma CVD is from tensile −3 × 10 ⁹ dyne / cm ² to tensile + 3 × 10 ⁹ dyne / cm ^2. The method for manufacturing an ink jet recording head according to claim 11. The silicon nitride film as an etching stop layer by plasma CVD has a gas composition of SiH ₄ : NH ₃ : N ₂ = 1: 0 to 1: 5 to 20, gas pressure 1 to 2 Torr, RF power density The method for manufacturing an ink jet recording head according to any one of claims 8 to 12, wherein the ink is deposited in a range of 0.2 to ² W / cm ² and a substrate temperature of 200 to 500 ° C.   The sacrificial layer is made of a metal film, and is made of Al, AlCu alloy, amorphous silicon by plasma CVD, polycrystalline silicon, porous silicon by anodization, or silicon dioxide obtained by oxidizing porous silicon. A method for manufacturing an ink jet recording head according to claim 13.   The method of manufacturing an ink jet recording head according to claim 8, wherein the alkaline etching solution is an etching solution that causes an etching rate difference due to a crystal plane of KOH, EDP, TMAH, or hydrazine. .

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