A method of making a cell sieve structure and a cell sieve structure
By forming nanosieve structures on a substrate and etching to create cavities, the problems of clogging and airflow drive in microfluidic filtration devices have been solved, enabling a highly efficient cell screening process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-14
- Publication Date
- 2026-03-24
AI Technical Summary
Existing microfluidic filtration devices are prone to clogging during cell screening and require additional airflow-driven structures to facilitate cell flow, resulting in complex operation and low efficiency.
A nanosieve structure is formed on a substrate, including multiple nanowire grooves of target size. Cavities are formed by etching from the back of the substrate upwards, suspending the nanosieve structure to form a cell sieve structure. The width of the nanowire grooves is the diameter of the target cell, providing vertical and horizontal flow channels to avoid clogging.
It enables cell screening without additional airflow, avoiding clogging issues and improving operational efficiency and equipment reliability.
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Figure CN117180988B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of cell screening, in particular to a cell screening structure preparation method and a cell screening structure. BACKGROUND
[0002] For cell separation and classification, usually a complex process and multiple additional "signal tags" are needed to identify target cells. In recent years, many new methods have been developed to avoid the use of biochemical markers. Label-free cell sorting technology uses the inherent physical biomarkers of cells to separate and classify cells. This means that the separation force depends only on the intrinsic physical property differences of the cells. Microfluidic systems can integrate a variety of sorting methods according to the physical parameters of the cells. The micro size of the microfluidic system provides a perfect interface for single cell operation and can be adjusted and controlled in many ways. Microfluidic or microscale filtration devices are a simple method of separating cells based on cell size or deformability as biomarkers. However, these filters are prone to clogging and contamination and require additional air flow driving structures to facilitate cell flow for screening. SUMMARY
[0003] The purpose of the present application is to provide a cell screening structure preparation method and a cell screening structure, which can avoid clogging during cell screening and do not require additional driving air flow to facilitate cell flow.
[0004] To achieve the above purpose, the present application provides the following technical solutions:
[0005] In a first aspect, the present application provides a cell screening structure preparation method, comprising:
[0006] forming a nanoscreen structure on a substrate; the nanoscreen structure comprises a plurality of nanowire grooves of a target size; the target size comprises a target width and a target height; the target width is the diameter of a target cell;
[0007] etching the substrate upward from the back of the substrate to form a cavity, so that the nanoscreen structure of the target area is suspended, to obtain a cell screening structure; the cavity is used to accommodate target cells screened by the nanoscreen structure.
[0008] For the effect description of the first set of claims, a detailed analysis should be made. The writing method is as follows:
[0009] Compared with the prior art, the cell screen structure preparation method provided by the application comprises the following steps: forming a nano screen structure on a substrate; the nano screen structure comprises a plurality of nanowire grooves with a target size; the target size comprises a target width and a target height; the target width is the diameter of a target cell; etching the substrate upward from the back of the substrate to form a cavity, so that the nano screen structure in a target area is suspended, and a cell screen structure is obtained; the cavity is used for accommodating the target cells screened by the nano screen structure. The nanowire grooves in the cell screen structure prepared by the cell screen structure preparation method have a vertical height, and no additional airflow is needed to drive the flow of a cell mixed solution, the transverse direction of the nanowire grooves can provide a long flow channel, effectively avoiding the problem of blockage, the width of the nanowire grooves can be prepared according to the size of the target cells to be screened, and in addition, the target cells to be screened can directly enter the cavity position through the nanowire grooves for collection.
[0010] In a second aspect, the application further provides a cell screen structure, comprising:
[0011] a substrate;
[0012] a nano screen structure formed on the substrate; the nano screen structure comprises a plurality of nanowire grooves with a target size; the target size comprises a target width and a target height; the target width is the diameter of a target cell; and the nano screen structure in a target area is in a suspended state; the nano screen structure in the target area is suspended by etching the substrate upward from the back of the substrate to form a cavity.
[0013] Compared with the prior art, the cell screen structure provided by the application has the same beneficial effects as the cell screen structure preparation method described in the above technical solution, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS
[0014] The accompanying drawings, which are included to provide a further understanding of the application and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:
[0015] Figure 1 A cell screen structure preparation method flow chart provided by the application;
[0016] Figure 2 A structure schematic diagram of the substrate after depositing N-layer laminates provided by the application;
[0017] Figure 3 A structure schematic diagram after forming a sacrificial structure provided by the application;
[0018] Figure 4 A structure schematic diagram after growing a formation layer provided by the application;
[0019] Figure 5Structure schematic diagram of the structure after the first side wall structure is formed by etching the formation layer provided by the present application;
[0020] Figure 6 Structure schematic diagram of the structure after the sacrificial structure is removed provided by the present application;
[0021] Figure 7 Structure schematic diagram of the structure after the second side wall structure is formed provided by the present application;
[0022] Figure 8 Structure schematic diagram of the side wall structure corresponding to the N / 2 array units provided by the present application;
[0023] Figure 9 Structure schematic diagram of the 2N side wall structures corresponding to the N layer stacks provided by the present application;
[0024] Figure 10 Structure schematic diagram of the structure after the auxiliary layer is formed provided by the present application;
[0025] Figure 11 Structure schematic diagram of the nanometer sieve provided by the present application;
[0026] Figure 12 Structure schematic diagram of the structure after the silicon nitride layer and the silicon oxide layer are epitaxially grown on the back of the substrate provided by the present application;
[0027] Figure 13 Structure schematic diagram of the structure after the patterned mask layer is formed provided by the present application;
[0028] Figure 14 Structure schematic diagram of the structure after the first cavity is formed by etching the substrate provided by the present application;
[0029] Figure 15 Sectional view of the cell sieve structure provided by the present application;
[0030] Figure 16 Bottom view of the cell sieve structure provided by the present application.
[0031] Reference signs:
[0032] 1-substrate, 2-first stack, 3-second stack, 4-sacrificial structure, 5-formation layer, 6-first side wall structure, 7-second side wall structure, 8-side wall structure corresponding to the N / 2 array units, 9-2N side wall structures corresponding to the N layer stacks, 10-auxiliary layer, 11-nanometer wire groove, 12-oxide layer, 13-nitride layer, 14-patterned mask layer, 15-first cavity, 16-second cavity. DETAILED DESCRIPTION
[0033] In order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the terms of "first", "second", etc. are used to distinguish the same or similar items with basically the same function and role. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and the order is not limited. Those skilled in the art can understand that the terms of "first", "second", etc. do not limit the quantity and execution order, and the terms of "first", "second", etc. also do not necessarily mean different.
[0034] It should be noted that in the present application, the words "exemplary" or "for example" are used to mean serving as an example, instance, or illustration. Any embodiment or design presented as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or advantageous than other embodiments or designs. Rather, the use of the words "exemplary" or "for example" is intended to present concepts in a particular manner.
[0035] In the present application, "at least one" means one or more, and "multiple" means two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b or c can represent: a, b, c, a and b, a and c, b and c, or a, b and c, where a, b, and c can be single or multiple.
[0036] Before introducing the embodiments of the present application, the related terms involved in the embodiments of the present application are first explained as follows:
[0037] Spacer process: side wall dry etching process, which is a self-aligned double imaging technology, using micro-nano technology, which can act on the protective layer on the surface of the gate side wall, to prevent the surface of the gate side wall from being damaged during the semiconductor structure forming process, and to extend the service life of the gate side wall.
[0038] TSV is the abbreviation of Through-Silicon Via, which means vertical electrical interconnection through silicon substrate.
[0039] The micro size of the microfluidic system selected for cell separation and classification provides a perfect interface for single cell operation, can be adjusted and controlled in multiple ways, can reduce the volume and cost of reagents, and has potential portability. However, the existing weir type, column type, cross flow type and other microfluidic filtering devices need to increase additional air flow to drive the flow of cell mixed solution, and are prone to blockage.
[0040] To solve the above problems, the present application provides a cell screen structure preparation method and a cell screen structure. The top-down structure can avoid the need for additional air flow driving structure. In addition, the lateral direction of the cell screen structure can provide a long flow channel to effectively avoid the problem of blockage. Next, the description is combined with the drawings.
[0041] Figure 1 A flow chart of a cell screen structure preparation method provided by the present application is shown in Figure 1 The method comprises the following steps:
[0042] First, a nanosieve structure is formed on a substrate. The nanosieve structure includes a plurality of nanowire grooves of a target size. The target size includes a target width and a target height. The nanowire grooves in the nanosieve structure form flow channels of the cell screen structure for screening cells of the target size. The width of the nanowire grooves is the diameter of the target cells, which can achieve the screening of cells of the target size. Since the cell screen structure needs to have vertical characteristics, the target cells in the cell liquid to be screened are vertically dropped under the action of gravity and separated from the cells larger than the target size in the cell liquid to be screened, thereby completing the cell screening. Therefore, the nanowire grooves formed need to have a certain height in the vertical direction.
[0043] Specifically, the preparation method of the nanosieve structure comprises the following steps:
[0044] Step 101: depositing N layers of laminates on the substrate. As shown in Figure 2 The N layers of laminates include N / 2 array units, which are basic array units with the bottom layer array unit. From bottom to top, they are basic array unit, second array unit,..., and N / 2 array unit. Each array unit includes first laminate 2 and second laminate 3. Each laminate includes a sacrificial layer and a material layer. The material of the sacrificial layer can be polysilicon, and the material of the material layer can be silicon oxide. N is greater than or equal to 2. Each array unit can correspond to form two nanowire grooves. The number of N can be set as needed. The sacrificial layer in the second laminate in the basic array unit is the layer formed by the nanowire groove, so the thickness of this layer needs to be the same as the target height to ensure that the formed cell screen structure has vertical characteristics. Deposition can be physical vapor deposition or chemical vapor deposition.
[0045] Step 102: for any one array unit in the N-layer stack, a sacrificial structure is formed on the material layer of the first stack, a forming layer is grown on the material layer of the first stack and the sacrificial structure, the forming layer is etched to form a first sidewall structure on both sides of the sacrificial structure, the sacrificial structure is removed and the material layer and the sacrificial layer of the second stack are etched downward with the first sidewall structure as a mask to form a second sidewall structure corresponding to the array unit.
[0046] Specifically, if the array unit is the array unit of the top layer, as shown in FIG. 4, a sacrificial structure 4 is formed by etching the sacrificial layer of the first stack by lithography, as shown in FIG. 5, a forming layer 5 is grown on the material layer of the first stack and the sacrificial structure by a thin film deposition process such as PECVD, LPCVD, etc. Figure 3 Figure 4
[0047] As shown in FIG. 6, the forming layer is etched by Spacer process dry etching to form a first sidewall structure 6 on both sides of the sacrificial structure, as shown in FIG. 7, the sacrificial structure is removed and the material layer and the sacrificial layer of the second stack are etched downward with the first sidewall structure as a mask to form a second sidewall structure 7 corresponding to the array unit; the thickness of the forming layer is transferred to the material layer and the sacrificial layer connected thereto in the form of width by etching the forming layer, to obtain a second sidewall structure with a target width, and then to obtain a nanowire groove with a target width. The presence of the material layer can avoid changes in the morphology of the nanowire template caused by the loss of the forming layer, so that the width of the formed nanowire is more accurate. Figure 5 Figure 6
[0048] After the second sidewall structure corresponding to the N / 2th array unit is formed, as shown in FIG. 8, the SiN layer and the SiO layer in the second sidewall structure of the array unit are removed to obtain a sidewall structure 8 corresponding to the N / 2th array unit, which is used as a sacrificial structure corresponding to the next array unit, and the steps of forming the second sidewall structure are repeated to form a second sidewall structure corresponding to the next array unit. Figure 8
[0049] Step 103: repeat step 102 N times to form 2N second sidewall structures corresponding to the N-layer stack.
[0050] Step 104: remove the forming layer and the material layer in the 2N second sidewall structures corresponding to the N-layer stack to obtain 2N sidewall structures corresponding to the N-layer stack.
[0051] As shown in FIG. 9, the 2N sidewall structures corresponding to the N-layer stack are used as a nanowire template to form a nanowire array. Figure 9 As shown, in this step, the width of each of the 2N sidewall structures 9 corresponding to the N-layer stack formed on the substrate is the same, which is equal to the thickness of the forming layer. The 2N sidewall structures 9 corresponding to the N-layer stack are formed on the upper surface of the material layer in the second stack of the basic array unit.
[0052] Step 105: Grow an auxiliary layer on the material layers of the 2N sidewall structures and the bottommost stack. For example... Figure 10 As shown, the auxiliary layer 10 can be SiO, and the auxiliary layer and the sacrificial layer are made of different materials.
[0053] Step 106: Planarize the structure of the 2N sidewall structures, excluding the sacrificial layer, and remove the remaining sacrificial layer to form 2N nanowire grooves, thus obtaining a nanosieve structure. For example... Figure 11 As shown, the width of the nanowire groove 11 is equal to the thickness of the forming layer.
[0054] The method described above for preparing nanosieve structures is not limited by photolithography and can form nanowire grooves with a width greater than or equal to 10 nm. This allows the final cell sieve structure to be used for screening cells with a diameter greater than 10 nm, and the size of the target cells can be adjusted. Furthermore, because the nanowire grooves have a certain height in the vertical direction, target cells can be separated from cells larger than the target size under the influence of gravity, eliminating the need for additional airflow to drive the flow of the cell mixture. The nanowire grooves also provide long flow channels in the horizontal direction for the cell sieve structure, effectively preventing clogging problems.
[0055] Step 107: Etch the substrate upwards from the back side to form a cavity, suspending the nanosieve structure in the target area to obtain a cell sieve structure. The cavity is used to contain the target cells screened by the nanosieve structure.
[0056] As an alternative approach, the steps to suspend the nanowires in the target area are as follows: First, a patterned mask layer is formed on the back side of the substrate using a photolithography process;
[0057] Specifically, such as Figure 12 As shown, an oxide layer 12 is epitaxially grown on the back side of substrate 1; the oxide layer 12 can be a silicon oxide layer, and the oxide layer is a thick layer, while the substrate is a Si substrate. Then, a nitride layer 13 is epitaxially grown on the back side of the oxide layer 12; the nitride layer can be a silicon nitride layer, and the nitride layer is a thin layer. A photoresist layer is coated on the back side of the silicon nitride layer; the photoresist layer is patterned using photolithography; the pattern can be rectangular or square, and the four sides of the pattern are at a predetermined distance from the edge of the substrate, such as... Figure 16 As shown, the shape is set along the longitudinal direction, and the four sides of the rectangle are at a certain distance from the edge of the silicon nitride layer, so that the uncorroded part of the material layer in subsequent steps provides support for the nanosieve structure.
[0058] As shown in Figure 13 The photoresist layer is etched to form a patterned mask layer 14.
[0059] As shown in Figure 14 The TSV process is used to etch the substrate upward to form a first cavity 15 with an inclined sidewall, taking the patterned mask layer as a mask.
[0060] Since the TSV deep silicon etching process etches a very thick Si, the Si thickness to be etched in the present solution is greater than 700 μm, and there is not so thick photoresist to resist etching Si. Therefore, the photoresist needs to be transferred to the hard mask layer by photolithography. However, the selectivity of SiN is very low when etching Si, so SiN will be etched very quickly. Therefore, SiO is mainly used for blocking, and the thickness of SiO is greater than 20 μm. The photoresist is still not enough to block, so the photoresist pattern is transferred through SiN first, so that SiN and SiO form a patterned mask layer together, which can realize the patterned etching of the silicon substrate.
[0061] As shown in Figure 15 The liquid HF solution or gaseous HF is used to soak the nanosieve structure, the substrate, and the material layer connected to the substrate, so that the material layer in the target area is corroded and disappears, and the nanosieve structure in the target area is in a suspended state, thereby obtaining a second cavity 16. The thickness of the material layer connected to the substrate needs to be less than a preset thickness.
[0062] The cell sieve structure formed by the above method at least includes: a substrate;
[0063] A nanosieve structure formed on the substrate; the nanosieve structure includes a plurality of nanowire grooves of a target size; the target size includes a target width and a target height; the target width is the diameter of the target cell; and the nanosieve structure in the target area is in a suspended state; the nanosieve structure in the target area is suspended by etching the substrate upward from the back of the substrate to form a cavity.
[0064] The cell sieve structure prepared by the cell sieve structure preparation method is not limited by photolithography, can realize a flow channel size of 10 nm and above, can be processed in multiple sizes according to needs, and the nanowire grooves form horizontal flow channels of the cell sieve structure in the horizontal direction and vertical flow channels in the vertical direction. Since the cell sieve structure has vertical characteristics, it does not need to add an additional air flow to drive the flow of the mixed solution, and the transverse direction of the cell sieve structure provides a long flow channel, effectively avoiding the problem of blockage.
[0065] In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.
[0066] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A method for preparing a cell sieve structure, characterized in that, include: A nanosieve structure is formed on a substrate; the nanosieve structure includes multiple nanowire grooves of a target size; The target dimensions include the target width and the target height; The target width is the diameter of the target cell; The substrate is etched upwards from the back side to form a cavity, suspending the nanosieve structure in the target area to obtain a cell sieve structure. The cavity is used to contain the target cells after they have been screened by the nanosieve structure; The formation of the nanosieve structure on the substrate includes: N layers are deposited on a substrate; each layer of the stack includes a sacrificial layer and a material layer, the sacrificial layer being deposited on the material layer; N is greater than or equal to 2; This forms 2N sidewall structures corresponding to the N-layer stack; An auxiliary layer is grown on the material layers in the 2N sidewall structures and the bottommost stack; Planarize the structure of the 2N sidewall structures except for the sacrificial layer and remove the remaining sacrificial layer to form 2N nanowire grooves, thus obtaining a nanosieve structure. The N-layer stack comprises N / 2 array units, each array unit comprising a first stack and a second stack, and the 2N sidewall structures forming the N-layer stack comprise: For any one of the array cells in the N-layer stack, A sacrificial structure is formed on the material layer of the first stack; A forming layer is grown on the material layer of the first stack and the sacrificial structure; The forming layer is etched to form a first sidewall structure on both sides of the sacrificial structure; The sacrificial structure is removed, and the material layer and sacrificial layer of the second stack are etched downwards using the first sidewall structure as a mask to form the second sidewall structure corresponding to the array unit; the N-layer stack corresponds to 2N second sidewall structures; Remove the forming layer and material layer from the 2N second sidewall structures corresponding to the N-layer stack to obtain the 2N sidewall structures corresponding to the N-layer stack.
2. The method for preparing the cell sieve structure according to claim 1, characterized in that, The thickness of the material layer connected to the substrate is less than a preset thickness; the etching of the substrate and the material layer connected to the substrate from the back side upwards to form a cavity includes: A patterned mask layer is formed on the back side of the substrate using photolithography. Using the TSV process, the substrate is etched upwards using the patterned mask layer as a mask to form the first cavity; The material layer connected to the substrate is immersed in liquid HF solution or gaseous HF to make the nanosieve structure in the target area suspended, thus obtaining a second cavity.
3. The method for preparing the cell sieve structure according to claim 2, characterized in that, The process of forming a patterned mask layer on the back side of the substrate using photolithography includes: An oxide layer is epitaxially grown on the back side of the substrate; A nitride layer is epitaxially grown on the back side of the oxide layer; A photoresist layer is coated on the back of the nitride layer; The photoresist layer is patterned by photolithography; the pattern is rectangular or square, and the four sides of the pattern are at a predetermined distance from the edge of the substrate; The nitride layer and the oxide layer are sequentially etched according to the photoresist layer to form a patterned mask layer.
4. The method for preparing the cell sieve structure according to claim 1, characterized in that, After obtaining the cell sieve structure, the process further includes: Drop the cell solution to be screened onto the cell sieve; The cell fluid to be screened flows along the height and horizontal directions of the nanowire grooves; Cells of the target size flow through the nanowire grooves into the cavity for collection, thus completing the screening of the cell fluid.
5. The method for preparing the cell sieve structure according to claim 1, characterized in that, The etching of the formation layer to form a first sidewall structure on both sides of the sacrificial structure includes: The forming layer is etched using a sidewall dry etching process to form two first sidewall structures on both sides of the sacrificial structure.
6. The method for preparing the cell sieve structure according to claim 2, characterized in that, The first cavity has inclined sidewalls.
7. The method for preparing the cell sieve structure according to claim 1, characterized in that, The target width of the nanosieve structure is greater than or equal to 10 nm.
8. A cell sieve structure, prepared by the cell sieve structure preparation method according to any one of claims 1-7, characterized in that, include: Substrate; A nanosieve structure formed on a substrate; the nanosieve structure includes multiple nanowire grooves of a target size; Target dimensions include target width and target height; The target width is the diameter of the target cell; the nanosieve structure in the target region is suspended. The nano-screening structure in the target region is suspended by etching the substrate from the back side upwards to form a cavity.
Citation Information
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