Adsorption platform

Abstract

The invention discloses an adsorption platform. The adsorption platform is prepared through the following steps that a plane glass substrate is obtained; carrying out sand blasting treatment on the surface of the plain glass substrate to form a surface structure with microscopic roughness; and cold polishing treatment is conducted on the surface subjected to sand blasting treatment, so that the protruding tops of the surface are ground to the same height plane, and a plurality of supporting points and an air channel network communicating with the supporting points are formed. According to the adsorption platform, gas can be quickly discharged, so that the imaging quality and the production efficiency are both considered.

Description

Technical Field

[0001] This application generally relates to the field of optical detection technology. More specifically, this application relates to an adsorption platform. Background Technology

[0002] In AOI inspection after semiconductor wafer dicing and other vision devices employing backlit positioning, it is typically necessary to stably attach the wafer-bearing film material to a transparent platform. A backlight is placed below the platform, and an inspection or positioning camera is mounted above it. The backlight passes through the platform and the product before imaging by the camera. To ensure image quality, the platform must possess high transmittance, high uniformity, and extremely high flatness. Furthermore, to meet yield requirements, it must enable rapid and stable attachment of the film material.

[0003] Currently, there are two main solutions. One is to use flat glass and perform grinding and hardening treatment. Although this can meet the requirements of light transmission and flatness, when relying on double-ring vacuum adsorption, air bubbles are easily formed between the film material and the glass due to poor gas expulsion. This causes the image in the bubble area to be out of focus, and the long venting time affects the equipment's productivity. The other solution is to laser-groove the flat glass to guide the gas to escape quickly. However, the edge of the groove will form a dark line in the projection, interfering with the uniformity of visual imaging and affecting the detection accuracy.

[0004] In view of this, this application provides an adsorption platform that enables rapid gas discharge while ensuring excellent light transmittance and flatness, thereby balancing imaging quality and production efficiency. Summary of the Invention

[0005] In order to at least solve one or more of the technical problems mentioned above, this application provides an adsorption platform.

[0006] The adsorption platform provided in this application is prepared through the following operations:

[0007] Obtain a planar glass substrate; The surface of the planar glass substrate is sandblasted to form a surface structure with micro-roughness; The surface after sandblasting is cold polished to grind the raised tops of the surface to the same height plane, forming multiple support points and a network of interconnected air passages.

[0008] In some embodiments, the planar glass substrate is quartz glass, which is masked before sandblasting to control the surface flatness tolerance to 0.005mm and the thickness tolerance to within ±0.05mm, and the shape is cut by laser processing and then machined to form stepped chamfers.

[0009] In some embodiments, the quartz glass is annealed before sandblasting at a temperature of 1000°C to 1100°C for 10 to 14 hours.

[0010] In some embodiments, the sandblasting process uses sand particles with a Mohs hardness of not less than 6, a mesh size of 300 to 500 mesh, and a sandblasting pressure of 2.5 to 3.5 atmospheres.

[0011] In some embodiments, the bump height of the surface structure with micro-roughness is 1 μm to 10 μm, and the bump density is 100 to 1000 bumps per square millimeter.

[0012] In some embodiments, the airway network is randomly distributed on the surface and interconnected, forming microchannels for exhausting gas.

[0013] In some embodiments, the adsorption platform has uniform light transmittance, with a transmittance of not less than 90% in the visible light range and a transmittance uniformity deviation of not more than 5%.

[0014] In some embodiments, the adsorption platform further includes at least one vacuum adsorption hole, which is connected to the gas channel network.

[0015] In some embodiments, the diameter of the adsorption platform is 150 mm to 300 mm, and the overall flatness is no greater than 10 μm.

[0016] In some embodiments, the adsorption platform is used in semiconductor wafer inspection equipment as a backlight adsorption platform.

[0017] Using the adsorption platform provided above, this embodiment of the application forms a surface structure consisting of highly consistent support points and a network of interconnected microscopic air channels by sandblasting and cold polishing the surface of the planar glass substrate. This enables rapid gas extraction, with an exhaust efficiency comparable to that of slotted glass. Simultaneously, the surface, after cold polishing, possesses both a smooth support surface and uniform optical properties, ensuring high light transmittance and imaging uniformity in backlight transmission and avoiding shadow interference. Furthermore, the tops of the support points are ground to be coplanar, giving the adsorption platform extremely high overall flatness on a macroscopic scale, which meets the stringent requirements for platform flatness in high-precision visual inspection. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, and the same or corresponding reference numerals denote the same or corresponding parts, wherein: Figure 1An exemplary working scenario of the adsorption platform provided in this application is shown; Figure 2 The preparation process of the adsorption platform according to an embodiment of this application is shown. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] It should be understood that the terms "comprising" and "including" used in the specification and claims of this application indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this specification and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0022] As used in this specification and claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0023] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0024] In practical applications, the adsorption platform provided in this application is used in semiconductor wafer inspection equipment as a backlight adsorption platform. This platform is the core component of the backlight vision inspection system, and its performance directly determines image clarity, inspection stability, and equipment cycle time.

[0025] Figure 1 An exemplary working scenario 100 of the adsorption platform provided in this application is shown. For example... Figure 1 As shown, the adsorption platform 101, as the core carrier component, is located between the uniform backlight 102 and the industrial camera 103, with the blue film 104 laid flat on it for inspection. The adsorption platform 101 is connected to an external vacuum system 108 through vacuum adsorption holes 105 on its bottom or side. Its unique microscopic air channel network enables rapid degassing and stable adsorption. Simultaneously, the functional surface, treated with sandblasting and cold polishing, provides a uniform light-transmitting interface while ensuring extremely high flatness, avoiding imaging shadows or distortion. During operation, the light emitted from the backlight 102 passes sequentially through the adsorption platform 101, the blue film 104, and the wafer 106, reaching the industrial camera 103. The industrial camera 103 receives the light and forms a high-contrast transmitted image, which is ultimately transmitted to the image processing system 107 for positioning, defect identification, and contour detection. Thus, the adsorption platform 101 achieves a highly efficient balance between optical performance, adsorption efficiency, and flatness requirements in the semiconductor back-end inspection process.

[0026] Figure 2 An exemplary flowchart of the preparation process 200 of the adsorption platform according to an embodiment of this application is shown.

[0027] like Figure 2 As shown, in step S201, a planar glass substrate is obtained.

[0028] Specifically, the planar glass substrate is preferably optical-grade quartz glass, which possesses excellent thermal stability, chemical inertness, and high light transmittance. Before sandblasting, the substrate undergoes masking to precisely control its surface flatness tolerance to 0.005 mm and thickness tolerance to within ±0.05 mm. Masking is a process that uses a reference surface to selectively grind and correct the substrate, effectively eliminating any warping or thickness unevenness inherent in the substrate. Subsequently, laser processing technology is used to cut the platform's shape according to the design drawings. This process minimizes the heat-affected zone and ensures edge precision. Finally, precision machining creates a specified stepped chamfer on the platform's outer edge. This chamfer prevents stress concentration during installation, which could lead to edge chipping, and also helps form an effective sealing boundary during vacuum adsorption.

[0029] Furthermore, the quartz glass substrate, after its shape has been processed, must undergo annealing to eliminate internal stress. The annealing process is carried out in a high-temperature furnace, with the temperature strictly controlled within the range of 1000°C to 1100°C, for example, 1050°C, and held at this temperature for 10 to 14 hours, for example, 12 hours. Subsequently, it must be slowly cooled to room temperature according to a pre-set cooling curve. This process thoroughly releases the stress accumulated in the material during cutting and rough grinding, significantly improving the dimensional stability and mechanical uniformity of the glass substrate, laying a solid foundation for subsequent surface micro-processing requiring high consistency.

[0030] In step S202, the surface of the planar glass substrate is sandblasted to form a surface structure with micro-roughness.

[0031] Specifically, sandblasting is a crucial step in forming the initial microstructure. The abrasive grains used must possess sufficient hardness, typically a Mohs hardness of at least 6, such as alumina or silicon carbide, to ensure effective indentation on the hard quartz glass surface. The mesh size of the abrasive grains is chosen between 300 and 500 mesh, as this range directly affects the roughness scale. A coarser mesh (e.g., 300 mesh) results in more pronounced bumps and grooves; a finer mesh (e.g., 500 mesh) produces a more delicate structure. The sandblasting pressure must be simultaneously controlled between 2.5 and 3.5 atmospheres. Pressure and mesh size work synergistically to determine the contour depth and uniformity of the surface microstructure. In a preferred embodiment, using 400-mesh alumina abrasive grains at 3.0 atmospheres achieves a good balance between efficiency and effectiveness.

[0032] Furthermore, the aforementioned sandblasting process creates a micro-rough structure with specific statistical characteristics on the surface. Measurements show that the height of the bumps in this structure ranges from 1 μm to 10 μm, and the bump density is between 100 and 1000 per square millimeter. These bumps and pits are randomly distributed on the surface, forming a continuous, undulating micro-topography. This topography provides the physical basis for the subsequent formation of functional support points and venting channels; its parameter range ensures sufficient machining allowance for subsequent polishing processes and enables the formation of an effective interconnected network.

[0033] In step S203, the surface after sandblasting is cold polished so that the top of the surface protrusion is ground to the same height plane, forming a network of multiple support points and connected air passages.

[0034] Cold polishing is a high-precision surface correction process that relies on selective material removal. This process typically uses equipment equipped with precision polishing discs (such as tin discs or polyurethane pads) and specific polishing slurries (such as cerium dioxide or silica sol slurries). During polishing, stable pressure and a constant rotation speed are applied, causing the polishing media to interact physicochemically with the glass surface. Because the raised peaks experience greater pressure and have easier contact with the polishing media, the material removal rate is faster. By precisely controlling the polishing time and process parameters, all randomly raised peaks can be gradually polished to a common, ideal optical plane.

[0035] Meanwhile, because the valley areas between the ridges experience less pressure and may be partially protected by a denser layer formed by previous sandblasting or polishing debris, their material removal rate is much lower than that at the peaks. Therefore, most of the original groove structure is preserved, and because the upper peaks are removed, the degree to which these grooves are interconnected at the bottom may actually increase.

[0036] Ultimately, the surface develops two main microscopic features: first, a large number of highly consistent (usually within submicron coplanarity) smooth micro-supports that support the wafer or blue film and provide optical-grade flatness; and second, a network of crisscrossing, randomly connected, and unpolished trenches among these supports that form microscopic channels throughout the adsorption region.

[0037] This randomly interconnected network of air channels constitutes a highly efficient microchannel system for gas exhaust. When the platform is connected to an external vacuum source through vacuum adsorption orifices, a pressure gradient is formed between the center and edge of the adsorption area through these microchannels. Air beneath the adsorbed material (such as the blue film) can rapidly diffuse from the center to the edge through these ubiquitous channels and is eventually extracted, thus avoiding the problem of bubble formation caused by obstructed exhaust paths in traditional flat glass. This structure achieves a similar effect to slotted air ducting, but because the channels are microscopic and random, they do not produce any regular dark lines or shadows in macroscopic projection.

[0038] The adsorption platform obtained through steps S201 to S203, combined with its surface characteristics, offers comprehensive performance advantages. Firstly, it exhibits excellent and uniform light transmittance. Within the visible light range (e.g., 400-700nm), its overall transmittance is no less than 90%. This is because the top of the support point has been polished into a smooth mirror surface, where light primarily undergoes specular transmission with minimal loss. While the retained micro-grooves cause some light scattering, their size is much smaller than the pixel resolution of the detection camera, and their distribution is highly uniform. When this scattered light is superimposed macroscopically, it forms a very uniform and soft transmitted light field, without producing bright or dark spots. The transmittance uniformity deviation can be controlled within 5%, fully meeting the uniformity requirements of high-precision backlight imaging.

[0039] In practical applications, the diameter of the adsorption platform can be designed according to the size of the wafer it supports, typically ranging from 150mm to 300mm. Despite the presence of microstructures on the surface, thanks to the precise coplanarization control of the peaks achieved through cold polishing, the overall macroscopic flatness of the platform can reach a high level of no more than 10μm, or even lower. This is crucial for inspection cameras with extremely small depths of field, ensuring image clarity across the entire field of view. Furthermore, the adsorption platform must include at least one vacuum adsorption port. This port is typically located in the non-working area on the back of the platform and is physically connected to the surface's microscopic gas channel network through internal drilling or design, thereby transferring the suction effect of the external vacuum system to the entire adsorption surface.

[0040] To illustrate the effectiveness of the implementation methods and parameter ranges of this application, three specific embodiments differing in key process parameters are provided below. These embodiments are all based on the above-described combination. Figure 2Based on the described preparation process 200, by adjusting the sandblasting process parameters, an adsorption platform with high flatness, high light transmittance uniformity and excellent exhaust performance was obtained.

[0041] Example 1 This embodiment provides an adsorption platform for backlight detection of semiconductor wafers, and its preparation process is as follows: Substrate preparation: Quartz glass was selected as the substrate material, with an initial thickness of 10.00 mm. First, a mask was processed to control the surface flatness tolerance to 0.005 mm and ensure the thickness tolerance was within ±0.05 mm.

[0042] Shape processing: Using laser cutting technology, the substrate is processed into a circular platform with a diameter of 200mm. Subsequently, a stepped chamfer is made on the outer edge of the platform through precision machining to facilitate installation and sealing.

[0043] Annealing: The quartz glass substrate with the processed shape is placed in an annealing furnace and held at 1050℃ for 12 hours. Then, it is slowly cooled in strict accordance with the process specifications to eliminate internal stress and ensure material uniformity.

[0044] Sandblasting: An automated sandblasting system is used to uniformly sandblast the entire upper surface of the substrate with a Mohs hardness of 6.5 and a mesh size of 400. The sandblasting pressure is controlled at 3.0 atmospheres, and the processing time is 90 seconds, thereby forming a uniform micro-rough structure on the surface.

[0045] Cold polishing: The surface after sandblasting undergoes precision cold polishing. This process uses a precision grinding disc and polishing fluid to grind the randomly protruding peaks on the surface to a common reference plane, while preserving most of the peak and valley areas. Ultimately, the surface forms a large number of highly uniform, tiny, smooth support surfaces, which are interconnected by grooves that are not completely ground, forming an air-guiding network.

[0046] Post-processing and inspection: After cleaning the platform, testing was performed. The overall flatness of the platform was measured to be 8 μm, the height of the micro-bumps was approximately 5 μm, and the density was approximately 500 bumps / mm². Testing in the visible light range (550 nm) showed an average transmittance of 92% and a uniformity deviation of 3%. A vacuum adsorption hole was created on the back of the platform, connecting it to the micro-channel network on the surface.

[0047] The platform is installed in AOI equipment for testing. After the wafer is placed, a vacuum is activated, which ensures stable adsorption and no bubbles or shadows in the imaging area, meeting the requirements for fast and uniform backlight detection.

[0048] Example 2 This embodiment provides another adsorption platform, the main difference between its preparation process and that of Example 1 lies in the sandblasting process parameters, as follows: Substrate preparation, shaping and annealing: The steps are the same as in Example 1, and a circular quartz glass substrate with a diameter of 150 mm is prepared.

[0049] Sandblasting: To obtain deeper grooves and improve exhaust capacity, 300-mesh alumina abrasive particles with a coarser mesh are used for sandblasting. The sandblasting pressure is set to 2.5 atmospheres and the processing time is extended to 120 seconds to obtain a more significant roughness.

[0050] Cold polishing: The same cold polishing process as in Example 1 was performed. Due to the higher initial roughness, the support points and groove structures formed after polishing were more pronounced. The final measured height of the micro-bumps was approximately 8 μm, and the density was approximately 300 bumps / mm².

[0051] Final characteristics: The overall flatness of the platform meets the requirement of 9μm, the light transmittance is 90%, and the uniformity deviation is 4%. Vacuum adsorption holes are also provided.

[0052] This platform is suitable for rapid positioning scenarios where high exhaust speed is required but absolute light transmittance requirements are less stringent.

[0053] Implementation 3 This embodiment provides yet another adsorption platform, the preparation process of which is as follows: Substrate preparation, shaping and annealing: The steps are similar to those in Example 1, and a large quartz glass substrate with a diameter of 300 mm is prepared.

[0054] Sandblasting: To obtain a finer surface and optimize optical uniformity, sandblasting is performed using 500-mesh silicon carbide abrasive particles with a finer mesh size. The sandblasting pressure is set to 3.5 atmospheres and the processing time is 75 seconds, aiming to achieve a finer surface texture.

[0055] Cold polishing treatment: After cold polishing, the surface microstructure is more refined. The measured bump height is approximately 2μm, the density is approximately 800 bumps / mm², and the airway network is denser.

[0056] Final characteristics: The overall flatness of the platform reaches 7μm. Thanks to the finer surface treatment, the light transmittance is increased to 93%, and the uniformity deviation is 2%.

[0057] This platform is particularly suitable for precision optical inspection of large-size wafers that require high resolution and high uniformity.

[0058] All three embodiments described above fall under the above-mentioned combination. Figure 2Within the described numerical range, the morphology of the surface microstructure can be actively controlled by adjusting key process parameters such as the mesh size of the sandblasting particles (300 mesh, 400 mesh, 500 mesh) and the pressure (2.5, 3.0, 3.5 atmospheres). For example, coarser sand particles and appropriate pressure help form more pronounced grooves, facilitating rapid venting; finer sand particles help form a more delicate and uniform surface, improving optical performance. The obtained platforms have different microstructural characteristics (bump height 1-10 μm, density 100-1000 bumps / mm²), but all meet the requirements of high flatness (≤10 μm), high light transmittance (≥90%), and rapid venting, fully demonstrating the feasibility of the technical solution and the rationality of the parameter range in this application. Those skilled in the art can select and adjust the parameters within the above range according to different detection priorities.

[0059] While numerous embodiments of this application have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will arise for those skilled in the art without departing from the spirit and intent of this application. It should be understood that various alternatives to the embodiments of this application described herein may be employed in the practice of this application. The appended claims are intended to define the scope of protection of this application and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. An adsorption platform, characterized in that, The adsorption platform is prepared by the following operation: Obtain a planar glass substrate; The surface of the planar glass substrate is sandblasted to form a surface structure with micro-roughness; The surface after sandblasting is cold polished to grind the raised tops of the surface to the same height plane, forming multiple support points and a network of interconnected air passages.

2. The adsorption platform according to claim 1, characterized in that, The planar glass substrate is quartz glass. Before sandblasting, it is masked to control the surface flatness tolerance to 0.005mm and the thickness tolerance to within ±0.05mm. The shape is cut by laser processing and then machined to form a stepped chamfer.

3. The adsorption platform according to claim 2, characterized in that, The quartz glass is annealed before sandblasting at a temperature of 1000°C to 1100°C for 10 to 14 hours.

4. The adsorption platform according to claim 2, characterized in that, The sandblasting process uses sand particles with a Mohs hardness of not less than 6 and a mesh size of 300 to 500 mesh, and the sandblasting pressure is 2.5 to 3.5 atmospheres.

5. The adsorption platform according to claim 1, characterized in that, The surface structure with micro-roughness has a bump height of 1 μm to 10 μm and a bump density of 100 to 1000 bumps per square millimeter.

6. The adsorption platform according to claim 5, characterized in that, The airway network is randomly distributed on the surface and interconnected, forming microchannels for exhausting gas.

7. The adsorption platform according to claim 1, characterized in that, The adsorption platform has uniform light transmittance, with a transmittance of not less than 90% in the visible light range and a transmittance uniformity deviation of no more than 5%.

8. The adsorption platform according to claim 1, characterized in that, The adsorption platform also includes at least one vacuum adsorption hole, which is connected to the gas channel network.

9. The adsorption platform according to claim 1, characterized in that, The diameter of the adsorption platform is 150mm to 300mm, and the overall flatness is no more than 10μm.

10. The adsorption platform according to any one of claims 1 to 9, characterized in that, The adsorption platform is used in semiconductor wafer inspection equipment as a backlight adsorption platform.

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