Ink inlet cavity structure of MEMS (micro-electromechanical system) thermal bubble type ink-jet printing head and preparation method of ink inlet cavity structure

Abstract

The invention discloses an MEMS hot bubble type ink-jet printing head ink inlet cavity structure and a preparation method, and relates to the technical field of MEMS ink-jet printing head preparation, the cavity structure comprises a silicon substrate layer, a CMOS layer and a cavity structure layer, a heating resistance layer is located in an ink storage cavity and right faces an ink-jet port, ink enters the ink storage cavity from an ink inlet cavity, and after being heated by the heating resistance layer, the ink enters the cavity structure layer, and then enters the cavity structure layer; and the ink is jetted from the ink jet port. According to the invention, the CMOS driving circuit part of the thermal bubble type ink-jet printing head and the cavity structure part of the ink-jet printing head are integrated on one wafer, so that the thermal bubble type ink-jet printing head is manufactured by integrating CMOS and MEMS processes on a single wafer, and compared with a process for manufacturing the ink-jet printing head by bonding two wafers, the process is relatively short and the cost is relatively low.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS inkjet printhead fabrication, and particularly to a structure and fabrication method of an ink inlet cavity for a MEMS thermal bubble inkjet printhead. Background Art

[0002] Most of the existing thermal bubble inkjet printheads need to be fabricated by bonding two wafers. As Figure 1 shown, one wafer is used to fabricate the circuit driving part based on the CMOS process, and the other wafer is used to fabricate the printhead cavity part based on the MEMS process. The principle is that the CMOS circuit controls the heating resistor to heat. When the liquid in the ink storage cavity is heated, the solubility of the gas inside it decreases, resulting in the precipitation of gas from the liquid to form bubbles, and the formed bubbles push the liquid to eject from the inkjet orifice.

[0003] The existing technical process involves a relatively long process such as wafer bonding. It requires the use of two wafers, resulting in a high cost and low integration. At the same time, the heating resistor part of the printhead is far from the inkjet orifice, leading to a low inkjet efficiency.

[0004] The invention patent with the application number 201811425039.2 discloses a piezoelectric MEMS inkjet printhead and its fabrication method. In this application, compared with the existing fabrication method of MEMS inkjet printheads, the overall process steps of the fabrication method of the piezoelectric MEMS inkjet printhead are fewer, the types of processes involved are fewer, the dimensional accuracy is higher, and the efficiency is also higher. It solves the technical problems of the existing fabrication method of piezoelectric MEMS inkjet printheads, such as a large number of process types involved, difficulty in ensuring the quality of the vibration plate, and high potential risks caused by bonding. However, its structure also has the problem that the inkjet printhead driving circuit is independent, with low integration, which is not conducive to the miniaturization of the printhead. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a structure and fabrication method of an ink inlet cavity for a MEMS thermal bubble inkjet printhead, which integrates the CMOS drive and the cavity part of the thermal bubble inkjet printhead on one wafer, and at the same time, the heating resistor is directly opposite to the inkjet orifice to improve the inkjet efficiency.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A structure and fabrication method of an ink inlet cavity for a MEMS thermal bubble inkjet printhead, including:

[0007] A silicon substrate layer, on which a CMOS layer is formed;

[0008] The CMOS layer, on which a cavity structure layer is formed, and a thermal bubble inkjet printhead driving circuit is formed inside the CMOS layer;

[0009] The cavity structure layer is interconnected with the CMOS layer, and a cavity structure for a thermal bubble inkjet print head is formed within the cavity structure layer.

[0010] As a further aspect of the present invention, the cavity structure layer includes a TEOS medium, metal interconnects, an insulating layer, a heating resistance layer, a dry film laminate, and a cavity structure region.

[0011] As a further aspect of the present invention, the cavity structure region formed within the cavity structure layer includes: an ink inlet cavity, an ink storage cavity, and an ink jet port; wherein the heating resistance layer is located within the ink storage cavity opposite the ink jet port, and the ink liquid enters the ink storage cavity from the ink inlet cavity, and after being heated by the heating resistance layer, is ejected from the ink jet port.

[0012] A preparation method based on the above cavity structure includes the steps:

[0013] S1. Form a CMOS layer on a silicon substrate layer, form a metal interconnect region on the CMOS layer circuit, and form a TEOS dielectric layer on the CMOS layer;

[0014] S2. Pattern the TEOS dielectric layer, deposit metal interconnects, the metal interconnects connect the metal interconnect region, and pattern them;

[0015] S3. Deposit a heating insulating layer and a heating resistance layer, and pattern the heating resistance layer;

[0016] S4. Continue to deposit a TEOS dielectric layer, and pattern the TEOS dielectric layer;

[0017] S5. Deposit metal wires, achieve metal wire interconnection, and pattern the metal wires;

[0018] S6. Continue to deposit a TEOS dielectric layer, and pattern the TEOS dielectric layer to expose the metal wire interfaces, forming a heating resistance region;

[0019] S7. Continue to form an ink inlet cavity, an ink storage cavity, and an ink jet port, constituting a cavity structure for a thermal bubble inkjet print head.

[0020] As a further aspect of the present invention, after patterning the TEOS dielectric layer in S2, first deposit a TaAI metal layer, and then deposit metal interconnects.

[0021] As a further aspect of the present invention, the heating resistance material is a Ta thin film; the insulating layer material is SiN.

[0022] As a further aspect of the present invention, S7 includes the steps:

[0023] S71. Pattern and form an ink inlet cavity connection port on the TEOS dielectric layer;

[0024] S72. Coating and patterning the photoresist, followed by baking in an oven to form a photoresist film on the metal wire interfaces, ink storage cavities, and ink inlet cavity connections.

[0025] S73. Flip the wafer so that the bottom side faces up, and perform patterning to form the ink inlet cavity.

[0026] S74. Flip the wafer so that the front side faces up, and remove the protective photoresist film.

[0027] S75. Apply a dry film and perform patterning; apply another dry film and perform patterning to form the ink storage cavity and the ink jet orifice.

[0028] As a further embodiment of the present invention, before coating and patterning the photoresist in S72, flip the wafer so that the bottom side faces up and thin the silicon substrate.

[0029] Advantages of the present invention:

[0030] 1. In the present invention, the CMOS drive circuit part of the thermal bubble inkjet print head and the inkjet print head cavity structure part are integrated on a single wafer, realizing the fabrication of a thermal bubble inkjet print head by integrating CMOS and MEMS processes on a single wafer. Compared with the process of fabricating an inkjet print head by bonding two wafers, the process flow is shorter and the cost is lower.

[0031] 2. In the present invention, the heating resistor of the thermal bubble inkjet print head is directly opposite the ink jet orifice, improving the inkjet efficiency.

[0032] 3. When performing deep silicon etching on the backside silicon substrate of the wafer in the present invention, by coating, patterning, and baking in an oven on the front side of the wafer, a photoresist film is formed to protect the front metal interfaces, the heating resistor working areas, the ink inlet cavity connections, and the ink storage cavity channels, preventing the ink inlet cavity from communicating with the front side through the channels and damaging the chuck of the etching machine.

[0033] 4. After patterning the photoresist on the front side of the wafer in the present invention and baking in an oven, the covered area of the photoresist is relatively small, which is beneficial to reducing heat accumulation during deep silicon etching and preventing etching from stopping. Description of the Drawings

[0034] Figure 1 Schematic diagram of the structure of an existing MEMS thermal bubble inkjet print head;

[0035] Figure 2 Schematic diagram of the structure of an ink inlet cavity of a MEMS thermal bubble inkjet print head and its preparation method according to the present invention;

[0036] Figures 3 to 16 Schematic diagram of the steps of the preparation method of the cavity structure according to the present invention. Detailed Embodiments

[0037] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0038] The existing thermal bubble jet print head needs to be formed by bonding two wafers. One wafer is used to fabricate the circuit driving part based on the CMOS process, and the other wafer is used to fabricate the print head cavity part based on the MEMS process. As Figure 1 shown, the process flow involves wafer bonding and other process flows that are relatively long. Using two wafers incurs a relatively high cost and low integration. At the same time, the heating resistor part of the print head is relatively far from the ink jet orifice, resulting in low ink jet efficiency.

[0039] In view of the above problems, as Figure 2 shown, the present invention discloses an ink inlet cavity structure of a MEMS thermal bubble jet print head, including: a silicon substrate layer, a CMOS layer, a cavity structure layer, etc.

[0040] Among them, a CMOS layer is formed on the silicon substrate layer, a cavity structure layer is formed on the CMOS layer, a thermal bubble jet print head driving circuit is formed in the CMOS layer, the cavity structure layer is interconnected with the CMOS layer, and a cavity structure for the thermal bubble jet print head is formed in the cavity structure layer.

[0041] The cavity structure layer includes TEOS dielectric, metal interconnects, a heating resistor region, a dry film laminate, etc. The cavity structure region formed in the cavity structure layer includes: an ink inlet cavity, an ink storage cavity, and an ink jet orifice; wherein the heating resistor layer is located in the ink storage cavity, facing the ink jet orifice. The ink liquid enters the ink storage cavity from the ink inlet cavity, is heated by the heating resistor layer, and then is ejected from the ink jet orifice.

[0042] With the above structure, the present invention integrates the CMOS driving circuit part of the thermal bubble jet print head and the ink jet print head cavity structure part on one wafer. At the same time, the heating resistor faces the ink jet orifice, improving the ink jet efficiency.

[0043] Based on the above cavity structure, the present invention discloses a preparation method for the ink inlet cavity structure of a MEMS thermal bubble jet print head, as Figures 3 - 16 shown, including the steps of:

[0044] S1. Form a CMOS layer on the silicon substrate layer, form a metal interconnect region on the CMOS layer circuit, and form a TEOS dielectric layer on the CMOS layer, as Figure 3 shown.

[0045] S2. After the TEOS dielectric layer is patterned, the TaAI metal layer is deposited first, and then the metal wiring is deposited. The metal wiring connects the metal interconnection regions and is patterned, as Figure 4 shown.

[0046] S3. The heating insulation layer and the heating resistance layer are deposited, and the heating resistance layer is patterned; among them, the material of the heating resistance layer is Ta thin film; the material of the heating insulation layer is SiN, as Figure 5 , Figure 6 shown.

[0047] S4. Continue to deposit the TEOS dielectric layer and pattern the TEOS dielectric layer, as Figure 7 shown;

[0048] S5. The metal wires are deposited to achieve the interconnection of the metal wires and are patterned, as Figure 8 and Figure 9 shown.

[0049] S6. Continue to deposit the TEOS dielectric layer and pattern the TEOS dielectric layer to expose the metal wire interfaces and form the heating resistance region, as Figure 10 shown.

[0050] S7. Continue to form the ink inlet cavity, the ink storage cavity and the ink jet orifice to form the cavity structure for the thermal bubble jet print head.

[0051] Through the above solution, the CMOS layer is formed on the silicon substrate layer, the TEOS dielectric layer is formed on the CMOS layer, and the metal wiring interconnection regions are formed in the TEOS dielectric layer to realize the interconnection between the CMOS layer driving circuit and the outside; at the same time, by forming the heating insulation layer and the heating resistance layer, the heating resistance region is formed, and the heating resistance region is aligned with the ink jet orifice, so as to integrate the CMOS driving circuit of the thermal bubble jet print head and the cavity structure part of the print head on a single wafer, and at the same time the heating resistance is aligned with the ink jet orifice to improve the ink jet efficiency.

[0052] Further, forming the cavity structure for the thermal bubble jet print head includes the steps of:

[0053] S71. Pattern the ink inlet cavity connection orifice on the TEOS dielectric layer, as Figure 11 shown.

[0054] S72. First, flip the wafer so that the bottom surface faces up, and thin the silicon substrate, as Figure 12 shown; then coat and pattern the photoresist, and perform oven baking to form the photoresist film for the metal wire interfaces, the ink storage cavity and the ink inlet cavity connection orifice, as Figure 13 shown.

[0055] S73. Flip the wafer so that the bottom side faces upward, and pattern the silicon substrate to form an ink inlet cavity, as Figure 14 shown.

[0056] S74. Flip the wafer so that the front side faces upward, and remove the protective film, as Figure 15 shown.

[0057] S75. Apply a first dry film and pattern it; apply a second dry film and pattern it to form an ink storage cavity and an inkjet port, as Figure 16 shown.

[0058] Through the above solution, the protected part on the front side of the wafer is patterned with photoresist and baked in an oven to form a film; during the deep cavity etching of the silicon substrate on the back side, the front metal interface, the heating resistor working area, the ink inlet cavity and the ink storage cavity channels are protected to prevent the ink inlet cavity from communicating with the front side through the channels and damaging the chuck of the etching machine.

[0059] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

[0060] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or simply means that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature has a lower horizontal height than the second feature.

Claims

1. A MEMS thermal bubble jet print head ink inlet cavity structure, characterized in that, Comprising: A silicon substrate layer, on which a CMOS layer is formed; The CMOS layer, on which a cavity structure layer is formed, and a thermal bubble jet print head driving circuit is formed within the CMOS layer; The cavity structure layer, which is interconnected with the CMOS layer, and a cavity structure for a thermal bubble jet print head is formed within the cavity structure layer.

2. The cavity structure according to claim 1, wherein The cavity structure layer includes TEOS dielectric, metal interconnects, an insulating layer, a heating resistor layer, a dry film laminate, and a cavity structure region.

3. The cavity structure according to claim 2, wherein The cavity structure region formed within the cavity structure layer includes: an ink inlet cavity, an ink storage cavity, and an ink jet orifice; wherein the heating resistor layer is located within the ink storage cavity opposite the ink jet orifice, and the ink liquid enters the ink storage cavity from the ink inlet cavity, and after being heated by the heating resistor layer, is ejected from the ink jet orifice.

4. The preparation method of the cavity structure according to any one of claims 1 to 3, characterized in that, Including steps: S1. Form a CMOS layer on the silicon substrate layer, form a metal interconnect region on the CMOS layer circuit, and form a TEOS dielectric layer on the CMOS layer; S2. Pattern the TEOS dielectric layer, deposit metal interconnects, the metal interconnects connect the metal interconnect region, and pattern them; S3. Deposit a heating insulating layer and a heating resistor layer, and pattern the heating resistor layer; S4. Continue to deposit the TEOS dielectric layer, and pattern the TEOS dielectric layer; S5. Deposit metal wires, achieve metal wire interconnection, and pattern the metal wires; S6. Continue to deposit the TEOS dielectric layer, and pattern the TEOS dielectric layer to expose the metal wire interface, forming a heating resistor region; S7. Continue to form the ink inlet cavity, the ink storage cavity, and the ink jet orifice, constituting the cavity structure for a thermal bubble jet print head.

5. The preparation method according to claim 4, characterized in that, After patterning the TEOS dielectric layer in S2, first deposit a TaAI metal layer, and then deposit metal interconnects.

6. The preparation method according to claim 4, wherein The heating resistor is made of Ta thin film, and the insulating layer is made of SiN.

7. The preparation method according to claim 4, wherein The S7 includes steps: S71. Pattern and form an ink inlet cavity connection orifice on the TEOS dielectric layer; S72. Coating and patterning photoresist, baking in an oven, forming a photoresist film for the metal wire interface, the ink storage cavity, and the ink inlet cavity connection orifice; S73. Flip the wafer so that the bottom surface faces up, and pattern and form the ink inlet cavity; S74. Flip the wafer so that the front surface faces up, and remove the protective photoresist film; S75. Form a dry film laminate one, and pattern it; form a dry film laminate two, and pattern it, forming the ink storage cavity and the ink jet orifice.

8. The preparation method according to claim 7, characterized in that, Before coating and patterning photoresist in S72, first flip the wafer so that the bottom surface faces up, and thin the silicon substrate.

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