Wafer coating method based on micro-channel structure

Abstract

The invention provides a wafer coating method based on a micro-channel structure. The method comprises the following steps: providing a micro-channel structure silicon wafer; tightly attaching the silicon wafer with the micro-channel structure to a wafer to be coated; dropwise adding a liquid coating material on the silicon wafer with the micro-channel structure, wherein the liquid coating material fills a micro-channel cavity unit on the silicon wafer with the micro-channel structure; after the micro-channel cavity unit is fully filled, the micro-channel structure silicon wafer is removed, and a uniform coating layer is formed; the micro-channel cavity unit is a regular polygon with not less than six sides, the thickness of the cavity wall is not more than 50 microns, the windowing gap is between 100 microns and 200 microns, and the inner angle of the cavity wall is more than 90 degrees. According to the invention, the liquid material is guided to flow through the micro-channel structure, uniform distribution is realized by utilizing capillary action and surface tension, the technical problems of non-uniform material distribution and inconsistent thickness in the existing wafer coating technology are solved, and the performance and reliability of the wafer are improved.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor packaging, and in particular to a wafer coating method based on a microchannel structure. Background Art

[0002] With the rapid development of integrated circuit technology, the continuous improvement of chip performance has put forward higher requirements for semiconductor manufacturing processes. In the semiconductor manufacturing process, wafer coating is a key process step, and its quality directly affects the performance and reliability of the chip.

[0003] Existing wafer coating technologies mainly include methods such as drop coating and spin coating.

[0004] The drip coating technology is to directly drip the coating material on the surface of the wafer. This method is simple to operate, but the material distribution is often uneven, and it is easy to form thickness differences in certain areas of the wafer, resulting in unstable product performance. The drip coating method is prone to overlapping height at the glue overlapping position, affecting the overall uniformity.

[0005] The spin coating technology spins glue on the wafer at high speed. The glue is first dropped in the center of the wafer and then spread to the entire wafer by rotating the wafer. However, due to the centrifugal force, the coating material tends to accumulate at the edge of the wafer or become thin in the center area, resulting in inconsistent thickness.

[0006] In addition, existing coating methods make it difficult to achieve good interface bonding between materials and wafers, especially when the viscosity of the coating material is high or there is a complex topological structure on the wafer surface. The interface bonding force between the coating material and the wafer is insufficient, which can easily lead to defects such as bubbles and delamination, thereby affecting the integrity and reliability of the packaging structure.

[0007] These deficiencies lead to problems such as uneven distribution of packaging materials, inconsistent thickness of packaging layers, and insufficient interface bonding between materials and wafers during the wafer packaging process, ultimately reducing the performance and reliability of the wafer. Summary of the invention

[0008] The object of the present invention is to provide a wafer coating method based on a microchannel structure to solve the problems of uneven distribution of packaging materials and inconsistent thickness of packaging layers.

[0009] In order to achieve the above technical objectives, the present invention provides a wafer coating method based on a microfluidic structure, comprising: Providing a microfluidic structure silicon wafer, wherein the microfluidic structure silicon wafer comprises a plurality of microfluidic cavity units distributed on the surface of the silicon wafer; Tightly attaching the microfluidic channel structure silicon wafer to the wafer to be coated; Dropping a liquid coating material on the microfluidic structure silicon wafer, the liquid coating material filling the microfluidic cavity unit; And when the microfluidic channel cavity unit is fully filled, the microfluidic channel structure silicon wafer is removed to form a coating layer.

[0010] Optionally, the total volume of the liquid coating material matches the total volume of the microfluidic channel cavity unit.

[0011] Optionally, the microfluidic channel cavity unit has a cavity wall, and the height of the cavity wall corresponds to the required coating material thickness.

[0012] Optionally, the cavity wall thickness of the microfluidic channel cavity unit is not greater than 50 μm.

[0013] Optionally, the inner angle of the cavity wall of the microfluidic cavity unit is greater than 90°.

[0014] Optionally, the shape of the microfluidic channel cavity unit is a regular polygon with no less than 6 sides.

[0015] Optionally, the number of sides of the regular polygon is an even number.

[0016] Optionally, the window gap of the microfluidic channel cavity unit is between 100 μm and 200 μm.

[0017] Optionally, the microfluidic channel cavity unit is formed by a silicon wafer etching process.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention achieves uniform distribution of liquid coating material on the wafer surface by designing a specific microchannel structure and utilizing physical effects such as capillary action and surface tension. The microchannel structure serves as a guide and control unit for the liquid coating material, accurately controlling the flow and distribution of the coating material, thereby solving the problems of uneven material distribution and inconsistent thickness in traditional coating methods. At the same time, due to the close fit between the microchannel structure and the wafer to be coated and the auxiliary filling of the capillary action, the interface bonding between the coating material and the wafer surface is strengthened, thereby improving the overall performance and reliability of the packaging structure.

[0019] In addition, the microfluidic cavity unit adopted in the present invention is a special structure with a regular polygon structure of no less than 6 sides, a controlled window gap between 100μm and 200μm, and a designed cavity wall inner angle greater than 90°, which further optimizes the filling process of the liquid coating material, reduces the impact force of the liquid on the inner wall, improves the filling uniformity and integrity, and ultimately achieves a higher quality wafer coating effect, providing important process support for high-performance chip packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flow chart of steps of a wafer coating method based on a microfluidic channel structure in an embodiment of the present invention; Figure 2 A schematic diagram of the steps of preparing a microfluidic channel structure silicon wafer and a wafer to be coated to be closely fitted together in an embodiment of the present invention; Figure 3 Schematic diagram of the steps of closely fitting a silicon wafer with a microfluidic structure to be coated in an embodiment of the present invention; Figure 4 Schematic diagram of the silicon chip structure of the microfluidic channel in the embodiment of the present invention; Figure 5 for Figure 4 A partial enlarged view of the microfluidic structure in the middle; Figure 6 Schematic diagram of the structure of the microfluidic chamber unit in an embodiment of the present invention.

[0021] In the figure, 1. Microfluidic structure silicon wafer; 11. Local microfluidic structure; 111. Cavity wall; 112. Window gap; 2. Wafer to be coated. DETAILED DESCRIPTION

[0022] A wafer coating method based on a microfluidic structure of the present invention will be described in more detail below in conjunction with the accompanying drawings, wherein preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation of the present invention.

[0023] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in illustrating the purpose of the embodiments of the present invention.

[0024] In this embodiment, a wafer coating method based on a microfluidic structure is provided. Please refer to Figure 1 - Figure 3 , including the following steps: S1: Provide a microfluidic structure silicon wafer 1, wherein the microfluidic structure silicon wafer 1 comprises a plurality of microfluidic cavity units distributed on the surface of the silicon wafer.

[0025] Wherein, the total volume of the liquid coating material matches the total volume of the microfluidic channel cavity unit.

[0026] In a specific example, a silicon wafer of the same size as the wafer to be coated with material is selected, and thinned and etched respectively according to the microchannel structure designed in the present invention. Taking a 12-inch wafer (300 mm in diameter) as an example, the microchannel structure silicon wafer 1 is designed with a flow channel structure that is evenly distributed over the entire wafer area, in order to ensure that the liquid material is guided by the microchannel structure and can evenly fill the entire bottom silicon wafer under the action of capillary action and liquid surface tension.

[0027] Please refer to Figure 4 - Figure 5 The microchannel structure silicon wafer 1 has a local microchannel structure 11, and the local microchannel structure 11 includes a plurality of microchannel cavity units. The microchannel cavity unit is used to guide the liquid coating material to be evenly distributed through capillary action after being bonded to the wafer 2 to be coated. Figure 4 The arrows in the figure schematically indicate the flow direction of the liquid coating material in the microfluidic channel cavity unit.

[0028] The microfluidic cavity unit has a cavity wall 111, and the height of the cavity wall 111 corresponds to the required coating material thickness. In practical applications, the microfluidic structure silicon wafer 1 is the same size as the wafer 2 to be coated, ensuring that the coating range can completely cover the wafer surface. For wafers of different specifications, microfluidic structure silicon wafers 1 of different sizes can be prepared accordingly.

[0029] The thickness of the cavity wall 111 of the microchannel cavity unit is not greater than 50 μm. In a specific example, the thickness of the cavity wall 111 can be appropriately adjusted according to the specific etching process capability, but the thickness should be kept small to maximize the effective coating area.

[0030] Please refer to Figure 6 The microfluidic cavity units on the microfluidic structure silicon wafer 1 are distributed in regular hexagons, forming a honeycomb-like structure.

[0031] In a specific example, the shape of the microfluidic channel cavity unit can be a regular polygon with no less than 6 sides, such as a regular hexagon, a regular octagon or a regular dodecagon.

[0032] The purpose of selecting a regular polygon with no less than 6 sides is to ensure that the inner angle of the unit cavity wall 111 is greater than 90°, so as to reduce the impact force of the liquid on the inner wall when the liquid material fills the cavity unit, so as to facilitate fuller filling of the cavity unit.

[0033] In a preferred embodiment, the number of sides of the regular polygon is an even number, such as 6, 8, 10, 12, etc. This design is to facilitate the splicing arrangement of the microfluidic cavity units on the surface of the silicon wafer, ensuring that the microfluidic structure can completely cover the entire silicon wafer surface without leaving any gaps.

[0034] The window gap 112 of the microfluidic cavity unit is between 100 μm and 200 μm. If the window gap 112 is too small, it will affect the effect of capillary action and cause incomplete filling; if the window gap 112 is too large, it may cause uneven flow of liquid material. Selecting an appropriate window gap 112 is crucial to achieve uniform coating.

[0035] The microfluidic channel cavity unit is formed by a silicon wafer etching process.

[0036] Specifically, deep reactive ion etching (DRIE), wet etching or other suitable micromachining processes may be used to process the silicon wafer to form a designed microfluidic channel structure.

[0037] In a specific example, a pattern of a microfluidic cavity unit may be first formed on a silicon wafer surface by photolithography technology, and then the pattern may be transferred to the silicon wafer by an etching process to form a desired three-dimensional microfluidic structure.

[0038] The microfluidic structure silicon wafer 1 for wafer coating provided in this embodiment can effectively guide the liquid material to be evenly distributed; by adjusting the cavity wall height, it can meet the coating application requirements of different thicknesses; it is manufactured using mature semiconductor processes such as silicon wafer etching, and has high precision and consistency. Under the conditions of proper cleaning and maintenance, the microfluidic structure silicon wafer 1 can be reused many times, reducing the coating cost; the microfluidic structure silicon wafer 1 can be used in conjunction with existing wafer processing equipment.

[0039] S2: The micro-channel structure silicon wafer 1 is tightly attached to the wafer 2 to be coated.

[0040] When applying the liquid material, the microfluidic structure silicon wafer 1 is first closely attached to the wafer to be coated. During the bonding process, it is necessary to ensure that there are no bubbles and impurities between the two to avoid affecting the uniformity of subsequent coating. The bonding can be performed by physical pressing or by using an appropriate temporary adhesive. The specific operation method belongs to the conventional means of those skilled in the art and will not be described in detail.

[0041] S3: dripping liquid coating material onto the microfluidic structure silicon wafer 1, wherein the liquid coating material fills the microfluidic cavity unit.

[0042] Use the drop coating method to drop an appropriate amount of liquid material on each area of ​​the wafer and let it stand. The liquid material will gradually fill the entire microchannel structure cavity under the force of capillary action. To ensure uniform filling, several injection points can be pre-designed on the silicon wafer so that the liquid material can be quickly distributed to the entire silicon wafer surface.

[0043] In a specific example, the total volume of the liquid coating material matches the total volume of the microfluidic cavity unit. This matching relationship can be established by calculating the total volume of the microfluidic cavity and then accurately controlling the volume of the liquid material added. In this way, it can be ensured that during the coating process, there will be neither incomplete filling due to insufficient material nor uneven thickness due to excessive material.

[0044] S4: When the microfluidic channel cavity unit is fully filled, the microfluidic channel structure silicon wafer 1 is removed, and the liquid coating material fills the microfluidic channel cavity unit.

[0045] After all the microchannel cavity unit structures are filled, the microchannel structure silicon wafer 1 is removed and allowed to stand. The material liquid will fill and level the gaps originally created by the cavity wall 111 of the microchannel cavity under the action of surface tension, and finally the entire surface of the wafer to be coated is evenly coated with the liquid material to form a uniform coating layer.

[0046] In the process of removing the microfluidic structure silicon wafer 1, care should be taken to control the peeling speed and angle to avoid disturbing the formed liquid coating layer. In a specific example, the microfluidic structure silicon wafer 1 can be removed by slowly vertically pulling to maximize the uniformity of the coating layer.

[0047] The inner angle of the cavity wall 111 of the microfluidic cavity unit is greater than 90°. This design helps to reduce the impact force when the liquid coating material is filled, and can reduce the adhesion of the liquid when removing the microfluidic structure silicon wafer 1, which is conducive to forming a uniform and flat coating layer.

[0048] The wafer coating method based on the microfluidic structure provided in this embodiment realizes uniform distribution and consistent thickness of the coating material on the wafer surface by designing a specific microfluidic structure silicon wafer 1 and utilizing physical phenomena such as capillary action and surface tension. Compared with the traditional drop coating and spin coating methods, this method has the following obvious advantages: The microfluidic structure design ensures that the liquid material can be evenly distributed on the wafer surface, avoiding local aggregation or missing phenomena that are prone to occur in traditional methods; thickness consistency is guaranteed, and high-precision control of the coating layer thickness is achieved by precisely controlling the height of the microfluidic cavity and the amount of liquid material used; the design of the microfluidic structure helps the liquid material to fully contact the wafer surface, thereby improving the interfacial bonding strength between the material and the wafer; the coating process relies on natural physical phenomena, reducing the influence of human factors and improving the stability and repeatability of the process.

[0049] In summary, the wafer coating method based on the microfluidic structure provided by the present invention realizes the control of the flow and uniform distribution of materials through the microfluidic structure silicon wafer composed of microfluidic cavity units, effectively solves the problems of uneven material distribution, inconsistent thickness and insufficient interface bonding force existing in the existing wafer coating technology, and provides a new solution for wafer coating technology, which helps to improve the performance and reliability of wafers.

[0050] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A wafer coating method based on a microfluidic channel structure, characterized in that: include: Providing a microfluidic structure silicon wafer, wherein the microfluidic structure silicon wafer comprises a plurality of microfluidic cavity units distributed on the surface of the silicon wafer; Tightly attaching the microfluidic channel structure silicon wafer to the wafer to be coated; Dropping a liquid coating material on the microfluidic structure silicon wafer, the liquid coating material filling the microfluidic cavity unit; And when the microfluidic channel cavity unit is fully filled, the microfluidic channel structure silicon wafer is removed to form a coating layer.

2. The method according to claim 1, characterized in that The total volume of the liquid coating material matches the total volume of the microfluidic channel chamber unit.

3. The method according to claim 2, characterized in that The microfluidic channel cavity unit has a cavity wall, and the height of the cavity wall corresponds to the required coating material thickness.

4. The method according to claim 3, characterized in that The cavity wall thickness of the microfluidic channel cavity unit is no more than 50 μm.

5. The method according to claim 3, characterized in that: The inner angle of the cavity wall of the microfluidic channel cavity unit is greater than 90°.

6. The method according to claim 1, characterized in that The shape of the microfluidic channel cavity unit is a regular polygon with no less than 6 sides.

7. The method according to claim 6, characterized in that The number of sides of the regular polygon is an even number.

8. The method according to claim 1, characterized in that The window gap of the microchannel cavity unit is between 100 μm and 200 μm.

9. The method according to claim 1, characterized in that: The microfluidic channel cavity unit is formed by a silicon wafer etching process.

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