Method for improving filiform pit defect of nano-pore of biological printing chip and nano-pore
By adding degluing treatment and combining wet dry etching in the preparation process of bioprinting chips, the problem of filamentous pit defects in nanopores is solved, and the defect-free nanopore structure is achieved, and the chip is improved performance and stability.
Patent Information
- Application Number
- CN202411423500.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-12
- Publication Date
- 2025-01-10
AI Technical Summary
In the preparation process of bioprinting chips, the by-product residue of chemical etchant during the formation of nanopores leads to filamentary pit defects, affecting the formation and performance of the structure.
By adding degluing treatment after the whole-side back-etching treatment, residues are removed, and a nanopore structure is formed by combining wet and dry etching to ensure defect removal and precise structure control.
The emergence of filamentous pit defects is effectively avoided, and a defect-free nanopore structure is obtained, which improves the performance and stability of the bioprinted chip.
Smart Images
Figure CN119284832A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of bioprinting technology and MEMS process, and in particular to a method for improving filamentous pit defects of nanopores in bioprinting chips and a nanopore. Background Art
[0002] Bioprinting technology is a multidisciplinary cross-integration technology that integrates biology, materials science, medicine, and computer science. It is a new technological means that uses computer three-dimensional models as "drawings" to assemble special "bio-inks" to ultimately create artificial organs and biomedical products. MEMS (Micro-Electro-Mechanical System) technology is a high-tech technology that combines microelectronics and micromachining technology. It is widely used in new sensors such as piezoelectric sensors, inertial sensors, and gas sensors. The micro-nanoscale characteristic dimensions of MEMS structures are not available in traditional machinery. Therefore, with the vigorous development of 3D bioprinting technology in recent years, MEMS technology has also been widely used in the fields of medicine, biology, etc.
[0003] In the preparation process of bioprinted chips, the formation of nanopores is involved. This preparation step involves a complex etching step, which includes the use of chemical etchants with organic components to etch the entire surface of silicon dioxide. These etchants will produce byproducts when reacting with the etched material. These byproducts will remain on the surface of silicon dioxide. When wet etching is performed to form a nanopore structure, the corrosive liquid will penetrate along the residues remaining on the surface and etch a thread-like pit at the edge of the nanopore, affecting the formation of the desired structure.
[0004] In order to improve the above problems, it is necessary to provide a method for improving the filamentous pit defects of the nanopores of bioprinting chips.
[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention
[0006] The object of the present invention is to provide a method and a nanopore for improving the filamentous pit defects of a bioprinting chip nanopore, so as to obtain a defect-free bioprinting chip nanopore structure.
[0007] In order to solve the above problems, in the first aspect, a method for improving the filamentous pit defects of the nanopores of a bioprinting chip is provided, comprising the following steps:
[0008] S1. providing a substrate, and performing an entire surface etching back process on the surface of the substrate;
[0009] S2, treating the surface of the substrate by a degumming process;
[0010] S3, forming a patterned photoresist on the surface of the substrate;
[0011] S4, using the patterned photoresist as an etching mask, sequentially performing wet etching and dry etching to form a nanopore structure.
[0012] By adding a desmearing process after the entire surface etching back process, the residues generated during the etching back can be removed, thereby avoiding the filamentary pit defects that may occur in the subsequent etching process.
[0013] In some embodiments, the substrate is made of silicon dioxide, and the whole-surface etching process is to remove a certain thickness of silicon dioxide layer by dry etching process. The whole-surface etching process can accurately control the thickness and shape of the dielectric layer, and prepare for subsequent processes.
[0014] In some embodiments, in step S2, the desmearing process is an oxygen plasma etching process. Oxygen plasma etching can effectively remove residues on the surface of the substrate.
[0015] In some embodiments, after step S2, the substrate is cleaned to reduce particle contamination and ensure the stability of subsequent processes.
[0016] In some embodiments, in step S4, the patterned photoresist is used as an etching mask, the wet etching is performed to form a first flow channel, and the dry etching is performed to form a second flow channel under the first flow channel to form the nanopore structure. Through the two-step etching process, a nanopore structure with a specific shape and size can be obtained.
[0017] In some embodiments, after step S4, a step of removing the photoresist is also included.
[0018] In some embodiments, the wet etching is performed using a hydrofluoric acid solution.
[0019] In some embodiments, the dry etching is plasma etching.
[0020] In a second aspect, the present invention further provides a bioprinting chip nanopore, wherein the nanopore is prepared according to a method for improving the filamentous pit defects of a bioprinting chip nanopore according to the first aspect.
[0021] The nanopore includes a first flow channel and a second flow channel, the second flow channel is located below the first flow channel and is interconnected; the first flow channel is an inverted cone structure, the opening size of the upper part is larger than the opening size of the lower part, and the width of the first flow channel decreases from the end farthest from the second flow channel to the end close to the second flow channel; the upper opening of the second flow channel is connected to the lower opening of the first flow channel and has the same size, and the width of the second flow channel is the same from top to bottom.
[0022] Compared with the prior art, the beneficial effects of the present invention mainly include: by adding a desizing process after the entire surface back-etching process, the residues generated during the back-etching can be removed, thereby avoiding the filamentary pit defects that may occur in the subsequent etching process and obtaining nanopores with abnormal defects. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0024] Figure 1 Schematic diagram of the generation of filamentary pit defects when preparing nanopores in the prior art.
[0025] Figure 2 A schematic diagram of the preparation process of a bioprinting chip nanopore provided by the present invention. DETAILED DESCRIPTION
[0026] The above and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention.
[0027] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.
[0028] Typically, a bioprinting chip is provided with a storage space for accommodating biological materials and a nanopore (i.e., a nozzle) connected to the space, and the biological materials can be discharged through the nozzle to achieve the corresponding bioprinting function.
[0029] like Figure 1 The figure shows a schematic diagram of the filamentary pit defects generated when preparing nanopores in the prior art. In the preparation process of bioprinting chips, before preparing the nanopore structure, the dielectric layer will be subjected to a full-surface back-etching process. The purpose of this step is mainly to accurately control the thickness and shape of the dielectric layer, remove excess materials, repair defects, improve the clarity of pattern definition, and prepare for subsequent etching processes. In addition, back-etching can also improve surface flatness and enhance the performance of the final device. Reference Figure 1 As shown in S101 in FIG. 1 , the substrate 1 is a silicon dioxide dielectric layer material. After the silicon dioxide dielectric layer is subjected to full-surface etching, residues 2 exist on its surface; Figure 1 As shown in S102 in FIG. 1 , when a patterned photoresist 3 is formed on the surface of the substrate 1 for preparing a subsequent nanopore structure, the residue 2 may be exposed on the side wall of the photoresist 3; then, as shown in FIG. Figure 1 As shown in S103, when the upper structure of the nanopore is wet-etched, since the corrosion rate of the residue 2 is much greater than the corrosion rate of the substrate 1, after the solution has completely corroded the residue 2, it will continue to corrode the substrate 1 along the hole under the photoresist 3, and a thread-like pit will be etched on the substrate 1, thereby causing a missing pattern and affecting the performance.
[0030] In fact, in the prior art, in order to carry out subsequent processes, the entire surface will be cleaned after etching back, but the residue cannot be effectively removed after the general cleaning process. We have tested by increasing the cleaning time and changing the cleaning solution, but found that simply increasing the cleaning time has no obvious effect; and the commonly used cleaning solutions are difficult to achieve effective removal, and it is difficult to find a cleaning solution that can effectively remove residue 2. It is difficult to achieve the removal of residue 2 by improving the cleaning process and it is costly. To this end, we provide a method and nanopore for improving the filamentous pit defects of the nanopores of a bioprinting chip.
[0031] The steps in the following embodiments do not correspond one to one with the summary of the invention.
[0032] Embodiment 1:
[0033] like Figure 2 Shown is a schematic diagram of the preparation process of a bioprinting chip nanopore provided in an embodiment of the present invention.
[0034] refer to Figure 2 The present invention provides a method for improving the filamentous pit defects of the nanopores of a bioprinting chip, and the preparation method comprises the following steps:
[0035] Step 1: Provide a substrate 1 and perform a full-surface etching process on the surface of the substrate 1.
[0036] refer to Figure 2 As shown in S201 in the present embodiment, the provided substrate 1 is a single-layer structure, which is made of silicon dioxide. The substrate 1 is then subjected to a full-surface etching process, that is, the entire upper surface of the substrate 1 is subjected to an unprotected dry etching process to etch away a certain thickness of the silicon dioxide dielectric layer, thereby preparing for subsequent processes. Figure 2 As shown in S201 in FIG. 1 , after the entire surface is etched back, residues 2 exist on the surface of the substrate 1 .
[0037] The provided substrate 1 is an operating platform for subsequent processes, and can be any substrate for forming or carrying semiconductor devices known to those skilled in the art. In other embodiments, the substrate 1 can be other materials, such as silicon nitride, silicon, germanium, etc.; in other embodiments, the substrate 1 can also be a multi-layer structure, for example, there are other layer structures on the other side of the substrate 1 that has not been subjected to the whole surface back etching process, and the other layer structures can be fixed or temporary, for example, it can be a silicon layer, other temporarily bonded substrates, formed etching stop layers or other functional structures, or bonded electrostatic films, etc.
[0038] It is understandable that when dry etching is performed on silicon dioxide material, various processes in the prior art may be used, such as plasma etching process, reactive ion etching process, etc., which will not be described in detail here.
[0039] Step 2: De-bonding the surface of substrate 1.
[0040] In the traditional process flow, a cleaning solution is generally used for cleaning after the entire surface is etched back, but the effect of this treatment step is limited, and a large amount of residue 2 is still not removed, which affects the stability of the subsequent process. In this embodiment, a step of degumming treatment is added before the traditional cleaning treatment, which can effectively solve the problem of residue 2. Figure 2 As shown in S202.
[0041] It is understood that the degumming process can adopt a wet degumming process or a dry degumming process. Specifically, in this embodiment, a dry degumming process (asher) is adopted to remove the residue 2. Compared with the traditional wet degumming process, the dry degumming process does not need to be soaked and dried with a chemical solvent, and the degumming process is easier to control, which is conducive to improving the yield rate.
[0042] In the application, there is no specific restriction on the reaction gas used in the dry stripping process, and it can be set according to the actual application requirements. As a feasible example, in this embodiment, the reaction gas of the dry stripping process can be oxygen, nitrogen, hydrogen, etc. For example, the oxygen ashing process (oxygen plasma etching process) is to remove the residue 2 by reacting oxygen atoms and residue 2 in a plasma environment. This is because the basic components of residue 2 are hydrocarbon organics, which are easy to react chemically with oxygen atoms ionized by oxygen to generate gases such as carbon monoxide, carbon dioxide and water.
[0043] In other embodiments, a wet stripping process may also be used, where a special chemical solvent is used to soak, clean and dry the substrate 1. The wet stripping process has the advantages of low cost and high efficiency.
[0044] Step 3: Cleaning the substrate 1.
[0045] The substrate 1 is cleaned, for example, with deionized water or a cleaning solution in the prior art. The main purpose of the cleaning process is to remove possible particle contamination to ensure the stability of subsequent processes.
[0046] Step 4: forming a patterned photoresist 3 on the surface of the substrate 1 .
[0047] refer to Figure 2 As shown in S203, the pattern on the mask is transferred to the photoresist 3 through a photolithography process (including steps such as coating, exposure, and development of the photoresist) to form a patterned photoresist 3; then, using the photoresist 3 as an etching barrier layer, the pattern can be transferred to the substrate 1 through an etching process to achieve the preparation of the desired structure.
[0048] Specifically, first, the photoresist is dropped onto the substrate 1 which is rotating at a high speed; then the substrate 1 is pre-baked so that the photoresist is firmly attached to the substrate 1, and then exposure and development are performed to dissolve and remove the photoresist in the unexposed area, thereby realizing the patterning of the photoresist 3. Then, after the post-baking treatment, subsequent etching and other processes can be performed.
[0049] Step 5: Using the patterned photoresist 3 as an etching mask, wet etching is performed to obtain the first flow channel 40 of the nanopore 4 .
[0050] In the present application, the nanopore 4 structure includes two parts. First, the upper structure of the nanopore 4, namely the first flow channel 40, is obtained by wet etching. Specifically, the surface of the substrate 1 is wet-etched with the patterned photoresist 3 as an etching mask to form the first flow channel 40. Figure 2As shown in S204 in . Here, the wet etching process is used to utilize the isotropic characteristics of wet etching, that is, the wet solution will not only etch silicon dioxide downward, but also have an etching effect on the surrounding silicon dioxide, and the etching rate in different directions can be adjusted to a certain extent. It can be understood that the wet etching here will produce undercutting below the photoresist 3, thereby causing the upper opening size of the first flow channel 40 to be larger (larger than the opening size of the patterned photoresist 3); and by utilizing the difference in etching rates in different directions, the first flow channel 40 can obtain a relatively gentle slope. Therefore, by reasonably controlling the process parameters of wet etching, such as the composition of the solution, the etching time, etc., a bowl-shaped first flow channel 40 can be formed. In this etching process, since the residue 2 has been removed by the degumming process in step 2, no filamentary pits will be formed at this time. In this embodiment, the wet etching process is carried out using a hydrofluoric acid solution.
[0051] Step 6: Using the patterned photoresist 3 as an etching mask, dry etching is performed to obtain the second flow channel 41 of the nanopore 4 .
[0052] In the present application, the nanopore 4 structure includes two parts. In step 5, the upper structure of the nanopore 4, i.e., the first flow channel 40, has been obtained by wet etching; here, the lower structure of the nanopore 4, i.e., the second flow channel 41, can be obtained by dry etching. Specifically, the surface of the substrate 1 is dry-etched with the patterned photoresist 3 as an etching mask until the substrate 1 is etched through to form the second flow channel 41, as shown in FIG. Figure 2 As shown in S205.
[0053] Due to the anisotropic characteristics of the dry etching process, the etching rate in the downward direction is much greater than that in the other directions, so the inner wall of the nanopore 4 can be well controlled, thereby obtaining a second flow channel 41 extending vertically downward, and the opening size of the second flow channel 41 is almost consistent with the opening size of the patterned photoresist 3, that is, the size control of the second flow channel 41 is more precise. Figure 2 As shown, it can be understood that the first flow channel 40 and the second flow channel 41 are interconnected, and the upper opening of the first flow channel 40 is larger than the lower opening of the first flow channel 40 , the lower opening of the first flow channel 40 is equal to the upper opening of the second flow channel 41 and the lower opening of the second flow channel 41 is equal to the lower opening of the second flow channel 41 .
[0054] It is understood that when dry etching is performed on silicon dioxide materials, various processes in the prior art can be used, such as plasma etching process, reactive ion etching process, etc., which will not be described in detail here. In this embodiment, the dry etching process used is a plasma etching process, and the etching process uses a fluorine-containing etching gas, specifically a mixed gas of CF4 gas and an inert gas (such as Ar and He); in other embodiments, the etching gas can use a chlorine-containing gas.
[0055] Step 6: remove the photoresist 3 on the surface of the substrate 1.
[0056] It can be understood that the desired nanopore 4 structure has been obtained in the above steps, and this step only requires removing the photoresist 3 mask on the surface of the substrate 1 .
[0057] Regarding the removal process of the photoresist 3, it belongs to the existing technology and can be independently selected according to actual needs or production conditions, and is not limited in this application.
[0058] Embodiment 2:
[0059] The present invention also provides a bioprinting chip nanopore, which is prepared by a method for improving the filamentous pit defects of a bioprinting chip nanopore as described in Example 1. The nanopore 4 includes a first flow channel 40 and a second flow channel 41, the second flow channel 41 is located below the first flow channel 40 and the first flow channel 40 and the second flow channel 41 are interconnected, wherein the first flow channel 40 is an inverted cone structure, the opening size of the upper part is larger than the opening size of the lower part, and the width of the first flow channel 40 decreases from the end away from the second flow channel 41 to the end close to the second flow channel 41; the upper opening of the second flow channel 41 is connected to the lower opening of the first flow channel 40 and has the same opening size, and the width of the second flow channel 41 is consistent from top to bottom.
[0060] In order to facilitate the description, some common English nouns or letters used in the present invention are only used for exemplary reference rather than restrictive interpretation or specific usage, and the protection scope of the present invention should not be limited by their possible Chinese translations or specific letters.
[0061] It should also be noted that, in this document, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.
Claims
1. A method for improving the filamentous pit defects of nanopores in a bioprinting chip, characterized in that: The steps include: S1. providing a substrate, and performing an entire surface etching back process on the surface of the substrate; S2, treating the surface of the substrate by a degumming process; S3, forming a patterned photoresist on the surface of the substrate; S4, using the patterned photoresist as an etching mask, sequentially performing wet etching and dry etching to form a nanopore structure.
2. A method for improving the filamentous pit defects of the nanopores of a bioprinting chip according to claim 1, characterized in that: The substrate is made of silicon dioxide, and the whole-surface etching process is to remove a silicon dioxide layer of a certain thickness through a dry etching process.
3. The method for improving the filamentous pit defects of the nanopores of a bioprinting chip according to claim 1, characterized in that: In step S2, the resist stripping process is an oxygen plasma etching process.
4. The method for improving the filamentous pit defects of the nanopores of a bioprinting chip according to claim 1, characterized in that: After step S2, the substrate is cleaned.
5. The method for improving the filamentous pit defects of the nanopores of a bioprinting chip according to claim 2, characterized in that: In step S4, the patterned photoresist is used as an etching mask, the wet etching is performed to form a first flow channel, and then the dry etching is performed to form a second flow channel under the first flow channel to form the nanopore structure.
6. The method for improving the filamentous pit defects of the nanopores of a bioprinting chip according to claim 1, characterized in that: After step S4, the method further includes a step of removing the photoresist.
7. The method for improving the filamentous pit defects of the nanopores of a bioprinting chip according to claim 5, characterized in that: The wet etching is performed using a hydrofluoric acid solution.
8. The method for improving the filamentous pit defects of the nanopores of a bioprinting chip according to claim 5, characterized in that: The dry etching is plasma etching.
9. A bioprinting chip nanopore, characterized in that: The nanopore is prepared according to a method for improving filamentous pit defects of nanopores in a bioprinting chip according to any one of claims 1 to 8.
10. The bioprinting chip nanopore according to claim 9, characterized in that: The nanopore comprises a first flow channel and a second flow channel, wherein the second flow channel is located below the first flow channel and is interconnected; The first flow channel is an inverted cone structure, the opening size of the upper part is larger than the opening size of the lower part, and the width of the first flow channel decreases from the end far away from the second flow channel to the end close to the second flow channel; The upper opening of the second flow channel is connected to the lower opening of the first flow channel and has the same size, and the width of the second flow channel is the same from top to bottom.