A kind of uniform glue device

Abstract

The application discloses a glue uniformizing device and belongs to the technical field of semiconductor manufacturing equipment. The glue uniformizing device comprises a glue uniformizing disc with a circular groove formed on a front surface; and a plurality of limiting rings with different inner diameters, which are detachably installed in the groove; wherein each limiting ring is used for fixing a wafer with an inner diameter corresponding to the limiting ring in the groove. Through the above mode, the limiting ring with a corresponding size can be selected according to the size of the wafer to be processed, the wafer is fixed in the groove of the glue uniformizing disc through the corresponding limiting ring, and the limiting ring and the groove are detachably connected, so that the cost of the glue uniformizing process is reduced, and the efficiency is also improved.

Description

Technical Field

[0001] This application belongs to the field of semiconductor manufacturing equipment technology, and in particular relates to a spin coating apparatus. Background Technology

[0002] In photolithography, the spin coating process is crucial for ensuring the uniformity of the photoresist film. Currently, rotary spin coating equipment is widely used. Its principle is to place the wafer on a carrier tray. During the coating process, the photoresist is sprayed onto the wafer from above, while the wafer rotates at an accelerated speed. Centrifugal force is used to spread the photoresist on the wafer surface and remove excess photoresist to form a photoresist film of uniform thickness.

[0003] After repeated use, it was found that the design of the spin coater has a major flaw: a spin coater can often only be used for wafers of a single size, which has a narrow range of applications. However, in actual production, it is often necessary to process wafers of multiple sizes, such as 6-inch, 8-inch, and 12-inch wafers. This leads to the need to frequently change spin coaters of different sizes, which not only results in high costs but also consumes a lot of time and effort, reducing production efficiency. Utility Model Content

[0004] The purpose of this application is to provide a spin coating device to solve the problem that a single spin coating device in the prior art cannot accommodate wafers of multiple sizes, resulting in high cost and low efficiency. By designing multiple limiting rings of different sizes, the device can select and replace the limiting ring of the corresponding size according to the size of the wafer to be processed, thereby improving industrial efficiency.

[0005] To solve the above-mentioned technical problems, this utility model provides a coating apparatus, comprising:

[0006] A uniform coating disc with circular grooves formed on its front surface;

[0007] Multiple limiting rings with different inner diameters are detachably installed in the groove;

[0008] Each limiting ring is used to fix the wafer corresponding to the inner diameter of the limiting ring in the groove.

[0009] Preferably, the bottom of the groove includes a circular first region and an annular second region surrounding the first region;

[0010] The first region is provided with a boss for supporting the wafer.

[0011] Preferably, in a direction perpendicular to the bottom of the groove, the first region is provided with a plurality of through holes penetrating the boss and the spin coater, the through holes being used to adsorb the wafer onto the surface of the boss through a vacuum source.

[0012] Preferably, the surface of the boss is further provided with a groove, and the bottom of the groove communicates with the through hole.

[0013] Preferably, the groove includes a plurality of concentric annular grooves and cross grooves, wherein the intersection of the cross grooves coincides with the center of the annular grooves.

[0014] Preferably, in the direction perpendicular to the groove, the difference between the height of the limiting ring and the height of the boss is less than 775 micrometers.

[0015] Preferably, the surface of the limiting ring opposite to the bottom of the groove is provided with a guide surface, and the guide surface is inclined radially downward.

[0016] Preferably, the outer side wall of the limiting ring is provided with an external thread, and the inner side wall of the groove is provided with an internal thread that mates with the external thread.

[0017] Preferably, the inner wall of the groove is provided with a buckle, and the outer wall of the limiting ring is provided with a slot, and the glue-equalizing disc and the limiting ring cooperate with the slot through the buckle.

[0018] Preferably, the limiting ring is made of plastic.

[0019] Compared with the prior art, this application designs multiple limiting rings with different inner diameters. Each limiting ring can fix a wafer of a specific size in the groove of the spin coater, and the limiting ring and the groove are detachably connected. This allows a spin coater to process wafers of various sizes, which not only reduces the cost of the spin coater process, but also improves efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the coating plate provided in the embodiments of this application;

[0021] Figure 2 A schematic diagram of a coating plate with a boss provided in an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of a grooved boss provided in an embodiment of this application.

[0023] Explanation of reference numerals in the attached drawings: 1-spreading plate, 11-groove, 2-limiting ring, 3-bore, 31-slot. Detailed Implementation

[0024] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0025] The specific embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0026] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] Spin coating is a core pre-process step in the photolithography stage of wafer fabrication. Essentially, it involves dispensing, high-speed rotation, and solvent evaporation to form a uniform, smooth, and defect-free functional thin film (primarily photoresist, but also including reflective coatings and protective layers) on the wafer surface. Its core function is to transfer the circuit pattern from the photomask to the photoresist on the wafer surface through exposure and development. The pattern is then etched onto the wafer. The quality of the photoresist film formed by the spin coating process directly determines the precision of the photolithographic pattern.

[0029] An exemplary method for preparing a photoresist film on a wafer surface includes: first, when the wafer substrate is stationary or rotating slowly, photoresist is dropped onto the wafer; then, the wafer is rotated rapidly, causing the photoresist to spread quickly across the entire wafer surface due to centrifugal force; then, excess photoresist is removed by continuing to rotate, ensuring that only a uniform photoresist coating layer remains on the wafer; finally, the coated wafer is rotated at a fixed speed until the photoresist solvent evaporates, forming a photoresist layer with uniform texture and thickness.

[0030] In the photoresist coating process described above, a photoresist coating device is indispensable. Its main function is to support the wafer and rotate the main body (the coating disk) to rotate the wafer around its axis of symmetry, thereby achieving photoresist coating. Currently, the problem of wafer fixation can be solved by creating grooves on the coating disk that match the wafer size. However, this design has a significant drawback: a groove of one size can only accommodate a single wafer size, resulting in a narrow range of applications. In actual production, it is often necessary to process wafers of various sizes, such as 6-inch, 8-inch, and 12-inch wafers. Therefore, processing these different sized wafers requires frequent changes of coating disks of different sizes, which is obviously costly and time-consuming, leading to low production efficiency.

[0031] To address the above issues, this application provides a spin coating device. A replaceable set of limiting rings is added within the groove of the spin coating tray. The limiting ring set includes multiple limiting rings with different inner diameters, and the limiting rings are detachably connected to the spin coating tray. This modular design allows wafers of different sizes to be fixed to the spin coating tray by limiting rings with corresponding inner diameters, thereby enabling a single device to be compatible with multiple wafer sizes.

[0032] refer to Figure 1 According to one embodiment of this application, the spin coating device includes a spin coating disk 1 with a circular groove 11 formed on its front surface; a plurality of limiting rings 2 with different inner diameters, the limiting rings 2 being detachably installed in the groove 11; wherein each limiting ring 2 is used to fix a wafer corresponding to the inner diameter of the limiting ring (2) in the groove 11.

[0033] The spin coater 1, as a whole, primarily serves to support the wafer to be processed, allowing the wafer to rotate around its own axis of symmetry to complete the spin coater process. Specifically, a circular groove 11 is provided on the surface of the spin coater 1 used to support the wafer. The groove 11 is recessed relative to the spin coater 1, designed to accommodate the largest wafer to be spin-coated, and its depth is greater than the wafer's thickness. After the wafer is placed in the groove 11, the groove 11 limits the lateral movement range of the wafer on the spin coater 1. However, when a smaller wafer (mainly where the wafer diameter is smaller than the groove 11's diameter) is placed in the groove 11 of the spin coater 1, because the groove 11 is larger than the wafer, the wafer may not be able to contact the inner wall of the groove 11, and thus may not be able to be fixed to the surface of the spin coater 1. This could lead to lateral displacement of the wafer during spin coater rotation, resulting in uneven surface coating, or even the wafer popping out of the groove 11.

[0034] Given the diversity of wafer sizes, this embodiment provides multiple retaining rings 2 with varying inner diameters to address the issue of securing wafers of different sizes. These retaining rings 2 can be replaced according to the different wafer sizes that need to be secured. Therefore, the retaining rings 2 are designed to be detachably installed within the grooves 11. Specifically, when a wafer of a certain size needs to be secured for a spin coating process, a retaining ring 2 with the corresponding inner diameter (the wafer's periphery is contact-surrounded by the inner wall of the retaining ring 2) is selected and installed into the groove 11 of the spin coating tray 1. When a wafer of another size needs to be secured for the spin coating process, a retaining ring 2 with the corresponding inner diameter is selected again, the previous retaining ring 2 is removed, and then reinstalled into the groove 11 of the spin coating tray 1, thus quickly enabling the replacement of the retaining rings 2. It is worth noting that each retaining ring 2 is used to secure the wafer with the corresponding inner diameter within the groove 11.

[0035] like Figure 2 As shown, the bottom of the groove 11 of the spin coater 1 is defined to include a circular first region and an annular second region surrounding the first region; the first region is provided with a boss 3 for supporting the wafer.

[0036] In a specific implementation, the wafer is placed into the groove 11, and the wafer will completely cover the boss 3, and the orthographic projection of the periphery of the wafer at the bottom of the groove 11 is located in the second region.

[0037] First, the upper surface of the boss 3 is higher than the bottom of the groove 11. This ensures that when the wafer is placed in the groove 11, only the boss 3 contacts the lower surface of the wafer. This prevents photoresist from leaking from the edge of the wafer to its sides and bottom during the spin coating process, thus preventing contamination of the non-processed areas of the wafer. The first and second regions completely cover the boss 3 with respect to the wafer, and the orthogonal projection of the wafer's periphery onto the bottom of the groove 11 lies within the second region. This ensures that when wafers of different sizes are placed in the groove 11, the central portion of the wafer can be supported by the boss 3. This further prevents wafer warping during the spin coating process and ensures stability in the spin coating process. Additionally, the boss 3 can be integrally formed with the bottom of the groove 11 of the spin coating disk 1 to provide a more stable support.

[0038] Furthermore, in a direction perpendicular to the bottom of the groove 11, the first region is provided with a plurality of through holes penetrating the boss 3 and the spin coater 1, the through holes being used to adsorb the wafer onto the surface of the boss 3 through a vacuum source.

[0039] In order to better fix the wafer during the spin coating process, in addition to the limiting ring 2, the wafer can also be adsorbed onto the surface of the boss 3 by vacuum means to restrict its vertical displacement in the groove 11.

[0040] The "protrusion" structure of the boss 3 first provides a closed cavity for vacuum adsorption: a slit layer with a thickness of only a few micrometers is formed between the back side of the wafer and the upper surface of the boss 3. The high vacuum area of ​​the through hole can instantly reach a uniform negative pressure, realizing synchronous adsorption of the entire wafer area. If the protrusion is removed and the wafer is directly attached to the bottom of the entire groove 11, the large-area planar contact will produce leakage channels due to micro-unevenness of the surface or particle inclusions, resulting in vacuum attenuation and uneven adsorption. When rotating, the wafer is prone to micro-slippage or local warping, directly introducing adhesive thickness error.

[0041] like Figure 3 As shown, specifically, the surface of the boss 3 is also provided with a groove 31, and the bottom of the groove 31 is connected to the through hole.

[0042] The groove 31 includes multiple concentric annular grooves and cross grooves, and the intersection of the cross grooves coincides with the center of the annular grooves.

[0043] The boss 3 is located at the bottom of the central groove 11 of the coating plate 1. Its surface can form multiple (multi-level) concentric annular grooves and cross grooves to form vacuum grooves 31. The bottom of the grooves 31 is connected to the external vacuum system through the aforementioned axial through hole. The surface of the boss 3 serves as the only contact support surface on the back of the wafer. Its flatness and levelness directly determine the orientation stability of the wafer during rotation. Through the vacuum adsorption path of the combination of grooves 31 and through holes, the boss 3 can provide uniform and adjustable negative pressure throughout the coating cycle, so that a rigid connection without slippage is formed between the wafer and the boss 3, thereby avoiding uneven coating thickness caused by wafer offset or warping.

[0044] In the direction perpendicular to the groove 11, the difference between the height of the limiting ring 2 and the height of the boss 3 is less than 775 micrometers.

[0045] Before spin coating, the wafer's thickness is its standard initial thickness, commonly known as the thickness of a "bare silicon wafer." This thickness is primarily determined by the wafer's diameter and is designed to ensure sufficient mechanical strength during various pre-manufacturing processes, preventing warping and cracking. For example, the typical thickness before spin coating for a 4-inch wafer is 525 micrometers, for a 6-inch wafer it is 150 micrometers, for an 8-inch wafer it is 725 micrometers, and for a 12-inch wafer it is 775 micrometers.

[0046] Therefore, when the difference between the height of the limiting ring 2 and the height of the boss 3 is less than 775 micrometers, the wafer to be processed can be fixed in the groove 11 of the spin coater by the limiting ring 2, and in the direction perpendicular to the bottom of the groove 11, the surface of the wafer is higher than the top surface of the limiting ring 2. This will allow the photoresist at the edge of the wafer to be thrown off the surface of the wafer due to centrifugal force during the spin coating process.

[0047] Due to the combined effects of hydrodynamic edge effects and the inherent properties of the photoresist, a thicker photoresist edge forms at the wafer periphery during the photoresist coating process. When photoresist is dropped onto the center of a rotating wafer, centrifugal force drives the photoresist to flow radially outward. However, when the photoresist reaches the wafer edge, the force system acting on it undergoes abrupt changes: on the one hand, centrifugal force causes it to continue moving outward; on the other hand, the surface tension of the liquid forces it to contract to minimize the surface area, while the substrate abruptly terminates at the edge, causing the photoresist to accumulate there. Furthermore, airflow disturbances and differences in evaporation rates at the edge also exacerbate the retention of the photoresist at the periphery.

[0048] From a physicochemical perspective, this phenomenon can be viewed as a macroscopic manifestation of the contact line pinning effect. The sharp edges of the wafer form an energy barrier, hindering the uniform detachment of the colloid from the substrate. The volume conservation of the colloid at the edges, its higher viscosity, and the rapid evaporation of volatile solvents at the edges collectively lead to increased local viscosity and decreased fluidity, resulting in an excess colloid layer that is significantly higher than that in the middle, the so-called "edge" or "colloid edge".

[0049] To avoid the problem described above, the height of the protrusion is precisely matched to the wafer thickness. When the wafer to be processed is placed and fixed in the groove 11, the upper surface of the wafer and the upper end face of the limiting ring 2 form a "zero-step" transition interface, which is a hydrodynamic prerequisite for suppressing the thick edge effect. If the wafer sinks to the bottom of the groove 11, a deep step will inevitably appear between the wafer surface and the upper end face of the limiting ring 2. This will cause the adhesive that has been centrifuged to the edge to undergo secondary backflow and capillary accumulation at the corner of the step due to surface tension and wall adhesion, which will exacerbate the thick edge. Therefore, the protrusion not only ensures vacuum reliability, but also creates a continuous and unobstructed flow channel at the edge of the wafer through the height difference design, allowing the adhesive to overflow smoothly and be thrown away, fundamentally achieving thick edge suppression and adhesive thickness uniformity.

[0050] Furthermore, the limiting ring 2 has a guide surface on its surface opposite to the bottom of the groove 11, and the guide surface is inclined radially downward.

[0051] In practice, the upper surface of the photoresist plate 1 is formed with an outward chamfer of 30° to 45° to serve as a guide surface for the photoresist and to prevent photoresist buildup. The upper surface of the limiting ring 2 is also milled with an outward chamfer of 30° to 45° to form a continuous slope with the guide surface, ensuring that there are no steps to obstruct the flow of the photoresist across the interface.

[0052] To obtain a photoresist film with the target thickness and high uniformity on a wafer, selecting the rotation speed is a crucial trade-off: the goal is to obtain a photoresist film with precise thickness and extremely high uniformity that meets the requirements of patterning processes by precisely controlling the rotation speed, the most easily adjustable parameter, under specific photoresist (fixed viscosity) conditions. This application also designs multiple limiting rings 2 with different inner diameters. It is necessary to ensure that during the rotation of the spin coater, the limiting rings 2 do not loosen or pop out due to the kinetic energy generated by the rotation. Therefore, the method of achieving a detachable connection between the limiting rings 2 and the spin coater 1 is also a key consideration.

[0053] In one embodiment of this application, the outer side wall of the limiting ring 2 is provided with an external thread, and the inner side wall of the groove 11 is provided with an internal thread that mates with the external thread.

[0054] When the limiting ring 2 needs to be installed in the groove 11, it can be installed in the groove 11 by rotating the limiting ring 2 in the corresponding direction of the thread. The connection between the two is relatively stable in this way, ensuring the stability of the two during the rotation and glue application process. When the limiting ring 2 needs to be removed from the groove 11, it can be removed by rotating the limiting ring 2 in the opposite direction of installation.

[0055] In another optional embodiment of this application, the inner sidewall of the groove 11 is provided with a buckle, and the outer sidewall of the limiting ring 2 is provided with a slot. The glue-spreading disc 1 and the limiting ring 2 can be assembled or disassembled by the buckle and the slot.

[0056] The combination of clips and slots not only enables the installation and removal of the limiting ring 2 and the groove 11, but more importantly, this installation and removal process is simple. During the process of applying epoxy resin to wafers of different sizes, this installation and removal method can save more time on changing the limiting ring 2, thus improving efficiency.

[0057] In one embodiment of this application, the limiting ring 2 is made of plastic. Specifically, it can be made of materials such as polyetheretherketone, polytetrafluoroethylene, polyphenylene sulfide, or polyvinylidene fluoride.

[0058] Engineering plastics have a much lower hardness than silicon wafers. When the limiting ring 2 contacts the wafer edge, even minor collisions or friction result in "soft contact," causing slight deformation or wear of the plastic, thus protecting the expensive wafer edges from chipping, cracking, or scratches. Furthermore, high-performance polymers such as polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE) exhibit excellent chemical resistance to photoresist solvents (such as acetone, PGMEA, and butyl acetate), preventing reactions or dissolution with the photoresist and avoiding the introduction of chemical contaminants. Additionally, these materials themselves have low volatile organic compound (VOC) and low precipitation characteristics, preventing the release of particles or gas molecules due to friction or slight heating during high-speed rotation, thus preventing contamination of the wafer surface.

[0059] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," or "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0060] The above description, based on the embodiments shown in the drawings, details the structure, features, and effects of this application. The above description is only a preferred embodiment of this application, but this application does not limit the scope of implementation to what is shown in the drawings. Any changes made in accordance with the concept of this application, or modifications to equivalent embodiments, that do not exceed the spirit covered by the specification and drawings, should be within the protection scope of this application.

Claims

1. An apparatus for spreading a glue, characterized in that include: A uniform coating disk (1) with a circular groove (11) formed on its front surface; Multiple limiting rings (2) with different inner diameters are detachably installed in the groove (11); Each limiting ring (2) is used to fix the wafer corresponding to the inner diameter of the limiting ring (2) in the groove (11).

2. The device of claim 1, wherein The bottom of the groove (11) includes a circular first region and an annular second region surrounding the first region; The first region is provided with a boss (3) for supporting the wafer.

3. The device of claim 2, wherein the first and second rollers are arranged to rotate in opposite directions. In a direction perpendicular to the bottom of the groove (11), the first region is provided with a plurality of through holes penetrating the boss (3) and the spin coater (1), the through holes being used to adsorb the wafer onto the surface of the boss (3) through a vacuum source.

4. The device of claim 3, wherein the first and second rollers are arranged to rotate in opposite directions. The surface of the boss (3) is also provided with a groove (31), the bottom of which is connected to the through hole.

5. The spin coating apparatus according to claim 4, characterized in that, The groove (31) includes multiple concentric annular grooves and cross grooves, the intersection of which coincides with the center of the annular groove.

6. The spin coating apparatus according to claim 3, characterized in that, In the direction perpendicular to the groove (11), the difference between the height of the limiting ring (2) and the height of the boss (3) is less than 775 micrometers.

7. The spin coating apparatus according to claim 6, characterized in that, The limiting ring (2) has a guide surface on its surface away from the bottom of the groove (11), and the guide surface is inclined radially downward.

8. The spin coating apparatus according to claim 1, characterized in that, The outer side wall of the limiting ring (2) is provided with an external thread, and the inner side wall of the groove (11) is provided with an internal thread that mates with the external thread.

9. The spin coating apparatus according to claim 1, characterized in that, The inner wall of the groove (11) is provided with a buckle, and the outer wall of the limiting ring (2) is provided with a slot. The glue-equalizing disc (1) and the limiting ring (2) cooperate with the slot through the buckle.

10. The spin coating apparatus according to any one of claims 1 to 9, characterized in that, The limiting ring (2) is made of plastic.

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