Manufacturing method of inkjet head chip
By using a wafer-to-wafer bonding method of polymer thin films and siloxane photoresist, the high wafer-level technical barriers and poor reworkability in traditional inkjet head chip manufacturing have been solved, enabling high-capacity and high-yield inkjet head chip manufacturing while reducing losses.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- MICROJET TECH
- Filing Date
- 2022-09-08
- Publication Date
- 2026-07-03
AI Technical Summary
Traditional inkjet head chip manufacturing methods have high technical barriers at the wafer level, as well as problems such as thermal stress and bubbles. These problems cause misalignment of polymers during the bonding process, making rework difficult and resulting in high losses.
By employing a wafer-to-wafer approach to combine polymer films and siloxane photoresist, and through steps such as photomask alignment, etching, and hot pressing, a nozzle sheet is formed and cross-linked, avoiding wafer-level bonding, simplifying the process, and retaining reworkability.
It achieves a combination of high wafer-level throughput and high grain-level yield, reduces losses, avoids thermal stress and bubble problems, and improves process flexibility and yield.
Smart Images
Figure CN115972774B_ABST
Abstract
Description
[Technical Field]
[0001] This case concerns a method for manufacturing inkjet head chips, specifically a method that integrates the advantages of high wafer-level throughput and high die-level yield, while also being reworkable to further reduce losses. [Background Technology]
[0002] Traditional inkjet head chips are manufactured using a die-level method, where a single inkjet head die is aligned and bonded to a single nozzle plate. While this method yields high yields, it is extremely time-consuming.
[0003] With the development of inkjet head manufacturing technology, high-throughput wafer-level manufacturing methods have emerged, such as bonding inkjet head wafers to nozzle wafers and directly defining nozzles on the inkjet head wafer. However, these large-area manufacturing techniques have high technical barriers, especially prone to poor-bond problems such as thermal stress and voids. Furthermore, during wafer-level bonding of polymers, alignment shift can occur due to shear stress, uneven pressure, and deformation. Moreover, rework is difficult after thermal processing, often resulting in losses due to poor yield. [Summary of the Invention]
[0004] This invention provides a method for manufacturing inkjet head chips that integrates the advantages of high wafer-level throughput and high die-level yield. It eliminates the need for wafer-level bonding machines, thus simplifying the process and allowing for rework, thereby further reducing losses.
[0005] To achieve the above objectives, one embodiment of this invention provides a method for manufacturing an inkjet head chip, comprising: 1) providing an inkjet head wafer, wherein a first surface of the inkjet head wafer has at least one polymer thick film; 2) providing a polymer thin film, wherein a second surface of the polymer thin film is coated with an adhesion promoter; 3) rolling the polymer thin film onto the polymer thick film of the inkjet head wafer in a wafer-to-wafer manner; 4) spin-coating a siloxane photoresist onto a third surface of the polymer thin film, and performing photomask alignment of the inkjet head wafer by examining the siloxane photoresist and the polymer thin film; 5) exposing the siloxane photoresist. 6) Develop the polymer film; 7) Etch the polymer film at the wafer level to form multiple nozzle plates and at least one protective rib; 8) Remove the protective rib; 9) Cut the inkjet head wafer to form multiple independent inkjet head dies with the multiple nozzle plates; 10) Hot press or bake the multiple inkjet head dies at high temperature, so that the adhesion promoter on the second surface of the multiple nozzle plates crosslinks with the polymer thick film of the multiple inkjet head dies to form a strong adhesion; 11) Remove the siloxane photoresist, wherein the polymer thick film of the multiple inkjet head dies is strengthened by high temperature baking to enhance the internal polymer polymerization and will not be eroded by the photoresist remover. [Attached Image Description]
[0006] Figure 1 This is a schematic diagram illustrating the steps of a method for manufacturing an inkjet head chip.
[0007] Figures 2A to 2N This is a schematic diagram illustrating a manufacturing process for an inkjet head chip.
[0008] [Symbol Explanation]
[0009] 10: Inkjet head wafer
[0010] 11: Polymer Thick Film
[0011] 12: Heating plate
[0012] 13: Electrode
[0013] 14: Test button
[0014] 15: Ink supply hole
[0015] 16: Thick film flow channel
[0016] 17: Thick film pad
[0017] 101: First Surface
[0018] 20: Polymer films
[0019] 21: Next, the accelerator
[0020] 22: Siloxane photoresist
[0021] 23: Thickened layer
[0022] 201: Second Surface
[0023] 202: Third Surface
[0024] 30: Spray nozzle plate
[0025] 31: Protective Rib
[0026] 4: Inkjet head crystals
[0027] S1~S10: Steps in the manufacturing method of wafer-level inkjet head chips
Detailed Implementation Methods
[0028] The implementation schemes that embody the characteristics and advantages of this case will be described in detail in the following section. It should be understood that this case can have various variations in different schemes, all of which do not depart from the scope of this case, and the descriptions and illustrations therein are essentially for illustrative purposes, not for limiting this case.
[0029] Please see Figure 1A method for manufacturing an inkjet head chip includes: 1. providing an inkjet head wafer 10, wherein a first surface 101 of the inkjet head wafer 10 has at least one polymer thick film 11; 2. providing a polymer thin film 20, wherein a second surface 201 of the polymer thin film 20 is coated with an adhesion promoter 21; 3. rolling the polymer thin film 20 onto the polymer thick film 11 of the inkjet head wafer 10 in a wafer-to-wafer manner; 4. spin-coating a siloxane photoresist 22 onto a third surface 202 of the polymer thin film 20, and performing photomask alignment of the inkjet head wafer 10 by examining the siloxane photoresist 22 and the polymer thin film 20; 5. exposing and developing the siloxane photoresist 22; 6. performing wafer-level etching on the polymer thin film 20 to form a plurality of nozzle plates 30 and at least one protective rib 31; 7. removing the protective rib. Rib 31; 8. Cut the inkjet head wafer 10 to form multiple inkjet head dies 4 with multiple nozzle plates 30; 9. Hot press or high temperature bake the multiple inkjet head dies 4, so that the adhesion promoter 21 on the second surface 201 of the multiple nozzle plates 30 cross-links with the polymer thick film 11 of the multiple inkjet head dies 4 to form a strong bond; 10. Remove the siloxane photoresist 22, wherein the polymer thick film 11 of the multiple inkjet head dies 4 is strengthened by high temperature baking and will not be corroded by the photoresist removal liquid.
[0030] Please refer to the accompanying text. Figure 2A In this embodiment, step 1 involves providing an inkjet head wafer 10, with at least one polymer thick film 11 on its first surface 101. It is noteworthy that the inkjet head wafer 10 is 6 inches, 8 inches, or 12 inches in size, but is not limited thereto; the size of the inkjet head wafer 10 can be adjusted according to actual needs. It is also noteworthy that the inkjet head wafer 10 has multiple heating plates 12, multiple electrodes 13, multiple test keys 14, multiple ink supply holes 15, and at least one polymer thick film 11, which includes multiple thick film channels 16 and multiple thick film pads 17. It is also noteworthy that the polymer thick film 11 can be made of epoxy, such as SU-8, but is not limited thereto; the material of the polymer thick film 11 can be adjusted according to actual needs.
[0031] Next, step 2 involves providing a polymer film 20, with an adhesion promoter 21 coated on its second surface 201. It is worth noting that the polymer film 20 can be made of polyimide (PI), but is not limited to this; the material can be adjusted according to actual needs. It is also worth noting that the thickness of the polymer film 20 is one of 12.5 μm, 25 μm, or 50 μm, but is not limited to this; the thickness can be adjusted according to actual needs. Furthermore, the adhesion promoter 21 can be applied only to the second surface 201 of the polymer film 20, or it can be applied to all surfaces of the polymer film 20; the application area can be adjusted according to process requirements. It is important to note that the adhesion promoter 21 is a medium for tightly bonding the polymer film 20 to the thick polymer film 11 of the inkjet head wafer 10; its thickness is very thin, therefore it does not affect the overall structure.
[0032] Please refer to the accompanying text. Figure 2B In this embodiment, step 3 involves rolling the polymer film 20 onto the polymer thick film 11 (including multiple thick film channels 16 and multiple thick film pads 17) of the inkjet head wafer 10 in a wafer-to-wafer manner. It is worth noting that the polymer film 20 has good rigidity and will not collapse or sag even when the ink supply hole 15 of the inkjet head wafer 10 is suspended.
[0033] Please refer to the accompanying text. Figure 2C In this embodiment, step 4 involves spin-coating a siloxane photoresist 22 onto the third surface 202 of the polymer film 20, allowing the siloxane photoresist 22 and the polymer film 20 to be transparent, and then aligning the inkjet head wafer 10 with the photomask. It is noteworthy that the siloxane photoresist 22 has excellent affinity for both organic and inorganic materials, allowing it to adhere well to the polymer film 20. Furthermore, both the siloxane photoresist 22 and the polymer film 20 are transparent, facilitating photomask alignment.
[0034] Please refer to the accompanying text. Figure 2D In this embodiment, step 5 involves exposing and developing the siloxane photoresist 22. It is worth noting that due to poor heat dissipation at the suspended area of the inkjet head wafer 10, plasma bombardment can be intensified; therefore, a single layer of siloxane photoresist 22 may occasionally be insufficient in blocking power. Please refer to the accompanying documentation. Figure 2E In another embodiment of this case, a thickening layer 23 is added to the siloxane photoresist 22 to enhance the etching resistance. The material of the thickening layer 23 is one of siloxane photoresist, aluminum oxide (Al2O3), aluminum (Al), titanium (Ti) or silicon dioxide (SiO2), but is not limited thereto. The material of the thickening layer 23 can be adjusted according to actual needs.
[0035] Please refer to the accompanying text. Figure 2F and Figure 2I In this embodiment, step 6 involves wafer-level etching of the polymer film 20 to form multiple nozzle plates 30 and at least one protective rib 31. It is noteworthy that the polymer film 20 is etched using anisotropic inductively coupled plasma (ICP) etching. The etching gases include oxygen (O2), carbon tetrafluoride (CF4), and sulfur hexafluoride (SF6), but are not limited to these. The type of gas, gas flow rate, process chamber pressure, temperature, and time during etching can be adjusted according to process requirements.
[0036] Please refer to the accompanying text. Figure 2G In this embodiment, the method further includes altering the cavity pressure and temperature during anisotropic inductively coupled plasma (ICP) etching of the polymer film 20 to increase the lateral etching of the bottom of the polymer film 20, resulting in a cone angle of 2° to 4°. Simultaneously, using only pure O2 plasma etching reduces the risk of over-etching of the plating layer such as tantalum (Ta) on the surface of the heating plate 12 by fluorine ions. Furthermore, the electrodes 13 and the thick film pad 17 of the inkjet head wafer 10 are covered and protected by the polymer film 20 to prevent etching damage and reduce the adhesion of etching residues.
[0037] Please refer to the accompanying text. Figure 2H and Figure 2I In this embodiment, step 7 involves removing the protective rib 31 to expose the electrode 13. It is noteworthy that the contact area between the polymer film 20 and the thick film pad 17 of the inkjet head wafer 10 is extremely small. Therefore, removing the protective rib 31 will not damage the thick film pad 17. In particular, the protective ribs 31 can be connected in series and removed in one go without any tools. A schematic diagram after removing the protective rib 31 is shown below. Figure 2J As shown.
[0038] Please refer to the accompanying text. Figure 2J and Figure 2I In the embodiment of this case, step 8 involves cutting the inkjet head wafer 10 to form multiple independent inkjet head dies 4 with nozzle plates 30. Subsequently, the nozzle plates 30 of each inkjet head die 4 are inspected.
[0039] Please refer to the accompanying text. Figure 2KIn this embodiment, step 9 involves hot-pressing or high-temperature baking the inkjet head die 4. The adhesion promoter 21 on the second surface 201 of the nozzle plate 30 cross-links with the polymer thick film 11 of the inkjet head die 4, achieving a tight bond without the need for an additional adhesive layer. It is noteworthy that bonding is performed only after the inkjet head dies 4 are cut into individual pieces, reducing the likelihood of poor-bond issues such as thermal stress and voids. It also avoids alignment shift caused by uneven shear stress or pressure and deformation during wafer-level bonding of the polymer. Furthermore, each inkjet head die 4's nozzle plate 30 is inspected before the thermal process. Therefore, nozzle plates 30 that fail inspection can be peeled off, and the inkjet head die 4 can be reassembled and aligned with another single nozzle plate 30 using conventional die-level manufacturing methods. Finally, hot-pressing or high-temperature baking completes the bonding process. This process design is reworkable, which further reduces losses.
[0040] Please refer to the accompanying text. Figure 2L In the implementation of this case, step 10 is to remove the siloxane photoresist 22, wherein the polymer thick film 11 of the inkjet head grain 4 is strengthened by high temperature baking to enhance the internal polymer polymerization and will not be corroded by the photoresist removal liquid.
[0041] Please refer to the accompanying text. Figure 2M and Figure 2N In this embodiment, the inkjet head die 4 is wire-bonded using inner lead bonding (ILB). It is worth noting that the electrode layout generally has two forms: one is placed on the short side of the inkjet head die 4, and the other is placed on the long side of the inkjet head die 4. There is often a test key 14 on the outside of the electrode. This test key 14 is mainly used to monitor the wafer process, and there will inevitably be exposed metal (such as the electrode of the test key 14). Therefore, adding a thick film pad 17 can effectively prevent short circuits in the ILB wire bonding.
[0042] In summary, this invention provides a method for manufacturing an inkjet head chip that integrates the advantages of high wafer-level throughput and high die-level yield. It eliminates the need for a wafer-level bonding machine, thus simplifying the process. Furthermore, rework can further reduce losses.
[0043] This case can be modified in various ways by a person skilled in this technology, but all of them are subject to the protection sought by the attached patent application.
Claims
1. A method for manufacturing an inkjet head chip, comprising: 1) Provide an inkjet head wafer, wherein a first surface of the inkjet head wafer has at least a polymer thick film; 2) A polymer film is provided, wherein a second surface of the polymer film is coated with an adhesion promoter; 3) The polymer film is rolled onto at least one polymer thick film on the inkjet head wafer in a wafer-to-wafer manner; 4) A siloxane photoresist is spin-coated on a third surface of the polymer film, and the siloxane photoresist and the polymer film are viewed to perform photomask alignment on the inkjet head wafer. 5) Expose and develop the siloxane photoresist; 6) The polymer film is etched at the wafer level to form multiple nozzle plates and at least one protective rib; 7) Remove at least one of the protective ribs; 8) The inkjet head wafer is cut to form multiple independent inkjet head grains with the multiple nozzle plates; as well as 9) The plurality of inkjet head dies are hot-pressed or baked at high temperature, and the adhesion promoter on the second surface of the plurality of nozzle plates cross-links with the at least one polymer thick film of the plurality of inkjet head dies to form a strong adhesion.
2. The method for manufacturing an inkjet head chip according to claim 1, wherein The inkjet head wafer size is 6 inches, 8 inches, or 12 inches.
3. The method for manufacturing an inkjet head chip according to claim 1, wherein The inkjet head wafer has multiple heating plates, multiple electrodes, multiple test keys, multiple ink supply holes, and at least one polymer thick film, and the at least one polymer thick film includes multiple thick film channels and multiple thick film pads.
4. The method for manufacturing an inkjet head chip as described in claim 1, characterized in that, The polymer film has a thickness of 12.5 μm, 25 μm, or 50 μm.
5. The method for manufacturing an inkjet head chip as described in claim 1, characterized in that, Step 5) further includes adding a thickening layer to the siloxane photoresist to enhance the etching resistance. The thickening layer material is one of siloxane photoresist, aluminum oxide, aluminum, titanium or silicon dioxide.
6. The method for manufacturing an inkjet head chip as described in claim 1, characterized in that, The polymer film in step 6) is etched by anisotropic inductively coupled plasma etching, and the etching gas includes oxygen, carbon tetrafluoride and sulfur hexafluoride.
7. The method for manufacturing an inkjet head chip as described in claim 1, characterized in that, Step 6) further includes increasing the lateral etching of the bottom of the polymer film by changing the cavity pressure and temperature of the etching process during anisotropic inductively coupled plasma etching of the polymer film, thereby generating a cone angle of 2°~4°.
8. The method for manufacturing an inkjet head chip as described in claim 1, characterized in that, It also includes: 10) Remove the siloxane photoresist, wherein the at least one polymer thick film of the plurality of inkjet head crystals is baked at high temperature to strengthen the internal polymer polymerization and will not be corroded by the photoresist removal liquid.
9. The method for manufacturing an inkjet head chip as described in claim 8, characterized in that, The inkjet head is cut into multiple inkjet head crystals before being joined together.
10. The method for manufacturing an inkjet head chip as described in claim 8, characterized in that, Step 8) If the multiple nozzle plates containing the multiple inkjet head dies are found to be abnormal during inspection, the multiple nozzle plates can be peeled off, and the multiple inkjet head dies can be re-aligned and reworked with another nozzle plate in a die-to-die manner.
11. The method for manufacturing an inkjet head chip as described in claim 8, characterized in that, Step 10) further includes internal pin bonding wire bonding of the plurality of inkjet head dies.