Glass substrate TGV blind groove processing method and glass substrate

Abstract

The invention discloses a glass substrate TGV blind groove processing method and a glass substrate, and the method comprises the steps: providing laser processing equipment which is integrated with a galvanometer scanning light path and a Bessel beam shaping light path; focusing laser focuses of the two light paths near the lower surface of the glass substrate to be processed; scanning the internal structure area forming the blind groove according to a preset filling path by utilizing a galvanometer scanning light path, and forming a first modified area in the glass substrate; a Bessel beam shaping light path is utilized, the edge contour area where the blind groove is formed is scanned according to a preset closed contour path, and a second modified area is formed in the glass substrate; and placing the glass substrate in an etching solution for wet etching to remove materials in the first modified area and the second modified area so as to form the blind groove. According to the glass substrate TGV blind groove processing method, the problems that in the prior art, the glass substrate blind groove processing efficiency and precision are difficult to consider at the same time, and the bottom morphology of the blind groove is poor are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of TGV hole fabrication technology, and in particular to a method for fabricating TGV blind grooves on a glass substrate and the glass substrate itself. Background Technology

[0002] Through Glass Via (TGV) technology, as an advanced three-dimensional interconnect technology, has broad application prospects in high-density microelectronic packaging, MEMS devices, and RF components due to the excellent high-frequency electrical properties, adjustable coefficient of thermal expansion, and low cost of glass materials. In the TGV process, the processing quality of the blind trench directly determines the effect of subsequent metallization and the reliability of the packaged components.

[0003] Currently, the main processing methods for TGV blind slots include sandblasting, plasma etching, photosensitive glass, and femtosecond laser processing.

[0004] Among them, sandblasting has low cost, but poor processing accuracy and severe edge chipping, and is only suitable for large-size blind trenches; plasma etching has an extremely low etching rate and can only produce blind trenches with specific conical structures, which is difficult to meet the needs of mass production; photosensitive glass is limited by expensive material costs and deformation problems caused by high-temperature processing, and its application scenarios are relatively limited.

[0005] With the application of the "cold processing" characteristics of femtosecond lasers, the technical route based on femtosecond laser-induced wet etching has become the mainstream high-precision TGV blind groove processing solution.

[0006] However, existing femtosecond laser TGV blind trench processing technologies generally employ a single beam-emission system architecture, which presents the following significant technical bottlenecks: First, existing single beam-emission systems mainly fall into two categories: one is a single Bezier cutting head system, which, while offering high processing precision and well-defined edges, suffers from extremely slow scanning speeds, making it inefficient for processing large-area blind trench internal structures and unsuitable for large-scale mass production at the board or wafer level; the other is a single focusing lens system, which, while possessing some continuous scanning capability, lacks the shaping characteristics of the Bezier beam, resulting in poor edge regularity and rough trench walls, failing to meet the requirements of high-density packaging for fine contours. Second, traditional processing techniques typically focus the laser on the upper surface or middle region of the glass substrate. This focus setting can easily lead to jagged unevenness at the bottom of the blind trench, over-etching forming through-grooves, or microcracks during subsequent wet etching, making it difficult to obtain a high-quality "flat-bottom" blind trench structure and severely affecting the reliability of subsequent metallization interconnects. Third, there is poor adaptability to irregular structures and insufficient process consistency. Existing technologies lack flexible path planning and optical path coordination mechanisms when processing irregularly shaped blind grooves such as triangles and ellipses. In addition, due to the lack of unified benchmark control, the processing parameters of different regions (such as the internal filling area and the edge contour area) often differ, resulting in poor uniformity of the morphology after etching, and the step-by-step processing by multiple devices is prone to cumulative errors.

[0007] In conclusion, overcoming the limitations of a single optical path system and improving the processing efficiency and quality of TGV blind slots has become an industry need. Summary of the Invention

[0008] The purpose of this invention is to provide a TGV blind groove processing method and glass substrate that can balance processing efficiency and precision, and solve the problem of flatness at the bottom of the blind groove.

[0009] To achieve the above objectives, the present invention provides a method for processing TGV blind grooves on a glass substrate, comprising: A laser processing device is provided, wherein the laser processing device integrates a galvanometer scanning optical path and a Bessel beam shaping optical path; The laser focal points of both the galvanometer scanning optical path and the Bessel beam shaping optical path are focused near the lower surface of the glass substrate to be processed; Using the galvanometer scanning optical path, the internal structural region forming the blind groove is scanned according to the preset filling path to form a first modified region in the glass substrate; Using the Bessel beam shaping optical path, the edge contour area forming the blind groove is scanned according to the preset closed contour path to form a second modified region in the glass substrate. The glass substrate, after being processed by the galvanometer scanning optical path and the Bessel beam shaping optical path, is placed in an etching solution for wet etching to remove the material from the first modified region and the second modified region, forming the blind trench.

[0010] Preferably, the scanning speed of the galvanometer scanning optical path is 1000-1500 mm / s, and the scanning speed of the Bessel beam shaping optical path is 150-250 mm / s.

[0011] Preferably, the laser focus is concentrated within a range of 0.05 mm to 0.1 mm above the lower surface of the glass substrate.

[0012] Preferably, the preset filling path is an equally spaced line scan path, and the light emission spacing of the line scan is 1-3 μm; the spacing between the edge contour area and the internal structure area is 2-4 μm.

[0013] Preferably, the galvanometer scanning optical path and the Bessel beam shaping optical path are connected to the same laser source through an electric beam splitter switching mechanism.

[0014] Preferably, before processing using the laser processing equipment, the method further includes identifying marker points on the surface of the glass substrate using a vision alignment system and establishing a global coordinate system to map preset filling paths and closed contour paths to the target processing position of the glass substrate.

[0015] Preferably, before or during processing using the laser processing equipment, the method further includes verifying the relative distance between the laser focus and the lower surface of the glass substrate using a vision system, and ensuring that the deviation of the relative distance between the laser focus and the lower surface of the glass substrate is less than or equal to a preset threshold.

[0016] Preferably, magnetic stirring is used during the etching process.

[0017] The present invention also provides a glass substrate, which includes a substrate body, wherein a TGV blind groove is formed on the substrate body based on the above-described glass substrate TGV blind groove processing method.

[0018] Compared with existing technologies, the above-mentioned technical solution provides a TGV blind trench processing method for glass substrates. By integrating a dual-optical-path system of galvanometer scanning and Bessel beam shaping into the same equipment, and employing a processing strategy of focusing the laser focal point near the lower surface of the glass substrate, it effectively solves the problems of difficulty in balancing efficiency and accuracy, as well as poor bottom morphology of blind trenches, in existing technologies. The galvanometer system utilizes high scanning speed to quickly remove large areas of material inside the blind trench, significantly improving processing efficiency; the Bessel system utilizes its long depth of focus to precisely trim the edges, ensuring a regular and vertical contour. Simultaneously, lower surface focusing combined with high energy parameters eliminates bottom jaggedness, residual cone tips, and microcracks caused by traditional upper surface focusing, achieving high-quality flat-bottom blind trench forming. This method eliminates the need for multiple clamping operations, ensures good process consistency, and can flexibly adapt to board-level or wafer-level mass production of rectangular and various irregularly shaped blind trenches. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the laser processing equipment in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram illustrating the positioning principle of the laser focus in an embodiment of the present invention.

[0021] Figure 3 This is a plan view of the glass substrate after optical path processing by a galvanometer scanning in an embodiment of the present invention.

[0022] Figure 4 This is a plan view of the glass substrate after Bessel beam shaping optical path processing in an embodiment of the present invention.

[0023] Figure 5 These are separate diagrams of the blind grooves formed on the glass substrate in the embodiments of the present invention.

[0024] Figure 6 This is a flowchart of the blind groove processing method in an embodiment of the present invention. Detailed Implementation

[0025] To illustrate the technical content, structural features, objectives, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0026] This embodiment discloses a method for processing blind grooves in glass substrates using TGV (Through GlassVia) technology that balances processing efficiency and morphological accuracy. This method primarily addresses the technical challenge of existing single-optical-path technologies being unable to simultaneously achieve large-area rapid removal and high-precision edge shaping.

[0027] Please refer to the following: Figures 1 to 6 The method mainly includes the following steps: S1. Provides laser processing equipment with integrated dual optical paths. First, such as Figure 1 A laser processing device is provided, which integrates two independent optical path systems in the same machine: a galvanometer scanning optical path 10 and a Bessel beam shaping optical path 11.

[0028] S2. Laser Focus J Focusing Positioning The laser focus J of both the galvanometer scanning optical path 10 and the Bessel beam shaping optical path 11 is focused near the lower surface 20 of the glass substrate 2 to be processed, such as... Figure 2 Unlike existing technologies that focus on the upper surface or intermediate layer, the laser focus J in this embodiment is located near the lower surface 20. In this way, after being modified by laser energy, it can be quickly removed by etching solution, thus achieving high-quality flat-bottom blind groove forming.

[0029] S3. Rapid scanning of the internal structural region (formation of the first modified region) Using a galvanometer to scan optical path 10, such as Figure 3 The internal structural region forming the blind groove is scanned according to the preset filling path L1. The galvanometer system utilizes its high-speed deflection characteristics to rapidly cover a large area inside the blind groove with high-energy laser light. The laser acts on the interior of the glass substrate 2, inducing material modification and forming a first modified region with refractive index changes or chemical bond breakage. The main purpose of this step is to efficiently pre-treat the host material that needs to be removed.

[0030] S4. Precise scanning of the edge contour area (formation of the second modified region) Using the Bessel beam shaping optical path 11, the edge contour region forming the blind groove is scanned according to the preset closed contour path L2, such as... Figure 4 Bessel beams, with their long focal depth and non-diffraction characteristics, can form modified channels with high aspect ratios. This step trims the edges along the final contour of the blind groove, forming a second modified region within the glass substrate 2. The main purpose of this step is to ensure the perpendicularity and regularity of the blind groove edges and eliminate edge chipping.

[0031] S5. Wet etching molding The glass substrate 2, after undergoing the two laser modification steps described above, is placed in an etching solution for wet etching. Because the material structure of the first and second modified regions has changed (e.g., become more porous), their etching rate in the etching solution is significantly higher than that of the unmodified regions. By controlling the etching conditions, the material in these two regions is removed, ultimately forming a TGV blind trench with uniform internal cavities, straight edges, and a flat bottom, as shown below. Figure 5 .

[0032] The above processing method effectively solves the problems of difficulty in balancing efficiency and accuracy and poor bottom morphology of blind grooves by integrating a dual optical path system of galvanometer scanning and Bessel beam shaping in the same equipment and adopting a processing strategy of focusing the laser focus J near the lower surface 20 of the glass substrate 2.

[0033] The galvanometer system uses high scanning speed to quickly remove large areas of material inside the blind groove, greatly improving processing efficiency; the Bezier system uses long depth of focus to precisely trim the edges, ensuring a regular and vertical contour.

[0034] Meanwhile, the lower surface focusing combined with high energy parameters eliminates the bottom serrations, residual cone tips and microcracks caused by traditional upper surface focusing. It can effectively eliminate the serrated residue at the bottom of the blind groove, prevent the formation of cone tips, and avoid bottom penetration (forming through holes) or microcracks caused by excessive thermal stress, thereby achieving flat bottom blind groove forming.

[0035] On the other hand, the laser processing equipment uses a femtosecond laser with a pulse width of less than 600 fs as the light source. To achieve dual-path multiplexing, the equipment is equipped with an electric beam splitter switching mechanism. This mechanism connects the laser source, the galvanometer scanning optical path 10, and the Bessel beam shaping optical path 11. Under the command of the co-controller, the electric beam splitter can quickly switch optical paths within milliseconds, and maintain the coaxiality of the optical axis during the switching process without the need for secondary calibration.

[0036] Furthermore, the laser processing equipment is equipped with a vision alignment system, typically consisting of a high-definition CCD camera 12 and an image recognition module. Before processing, the vision system identifies the marked points on the surface of the glass substrate 2 and establishes a global coordinate system. The controller maps the preset blind groove processing drawing (including the internal filling path L1 and the edge closing contour path L2) into this global coordinate system, ensuring that the laser processing position is precisely matched with the actual position of the substrate, with the error controlled within the micrometer level.

[0037] Furthermore, to ensure the accuracy of laser focusing near the lower surface 20, the relative distance d between the laser focus J and the lower surface 20 of the glass substrate 2 is checked before or during processing using a vision system or a dedicated distance sensor. If d is detected to exceed a preset threshold (e.g., ±0.02mm), the controller will automatically adjust the Z-axis height or the optical focusing unit to ensure that the focus J is always locked in the set area near the lower surface 20.

[0038] In addition, the equipment uses a high-precision XY axis motion platform 13 to support the glass substrate 2, and works with a vacuum adsorption fixture 14 to flatten and adsorb the board-level or wafer-level glass substrate 2 through vacuum negative pressure, preventing the substrate from warping during processing and causing the laser focus J to shift.

[0039] In another embodiment, for the galvanometer scanning optical path 10, in order to achieve rapid modification of large-area materials, the galvanometer scanning speed is set to 1000-1500 mm / s. For example, it is set to 1200 mm / s. This speed is much higher than the traditional mechanical axis movement speed, which can significantly shorten the single-hole processing time.

[0040] For the Bessel beam shaping optical path 11, to ensure edge quality and trajectory following accuracy of the irregular contour, the scanning speed is set to 150-250 mm / s. For example, it can be set to 200 mm / s. The lower speed helps to deposit sufficient energy density to form a continuous, smooth Bessel-modified channel.

[0041] Furthermore, the Z-axis position of the laser focus J is crucial for forming the flat-bottomed blind groove. In this embodiment, the laser focus J is focused within a range of 0.05 mm to 0.1 mm above the lower surface 20 of the glass substrate 2, i.e., 0.05 mm ≤ d ≤ 0.1 mm.

[0042] For example, for a glass substrate 2 with a thickness of 0.7 mm, the laser focus J is positioned 0.08 mm above the lower surface 20. This position ensures that energy is effectively applied to the bottom material while avoiding penetration of the lower surface 20.

[0043] In another embodiment, the path planning strategy for laser scanning is as follows: For the internal structural region forming the blind slot, an equidistant line scanning path is used. The beam emission spacing X1 of the line scanning is set to 1-3 μm (e.g., ...). Figure 3 For example, X1 is set to 2 μm. This density of scan lines ensures that the internal material is adequately modified, leaving no residue after etching.

[0044] For the edge contour area that forms the blind groove, a closed contour path L2 is used (adapted to any shape such as rectangle, circle, ellipse, etc.).

[0045] A certain spacing X2, set at 2-4 μm, is reserved between the edge contour area and the internal structure area. Figure 4 For example, X2 is set to 3μm. This spacing ensures connectivity between the interior and the edge after etching, while also preventing excessive heat accumulation or edge chipping caused by overlapping energy in the two parts.

[0046] In another embodiment, the specific method for wet etching and post-processing is as follows: The etching solution uses a hydrofluoric acid-based mixed etching solution. Of course, an alkaline solution can also be used as the etching solution. In a specific formulation, the etching solution is made by mixing hydrofluoric acid (HF) and nitric acid (HNO3) in a volume ratio of 4:1, and 1% fluoroboric acid (HBF4) can be selectively added as an inhibitor to balance the etching rate and surface quality.

[0047] The etching conditions are as follows: Temperature: Controlled between 25-35℃. For example, a constant temperature of 30℃. Too high a temperature will cause the reaction to be too violent and difficult to control, while too low a temperature will result in insufficient efficiency.

[0048] Time: The etching time should be controlled between 40 and 50 minutes. The specific time should be adjusted according to the required depth of the blind groove.

[0049] Stirring: Magnetic stirring (e.g., 100 rpm) is used throughout the etching process. Stirring ensures that the etching products are discharged from the hole in a timely manner, and that fresh etching solution enters the hole, ensuring uniform etching.

[0050] In addition, after etching is completed, the product is rinsed with deionized water (to remove residual acid), ultrasonically cleaned with anhydrous ethanol (to remove impurities), and finally dried in an oven (e.g., at 80°C) to obtain the finished product.

[0051] In summary, this invention discloses a method for processing TGV blind grooves on a glass substrate. The following description uses a wafer-level borosilicate glass substrate 2 with a diameter of 300 mm and a thickness of 0.7 mm as an example.

[0052] Processing objective: To form several elliptical TGV blind grooves on glass substrate 2, with a major axis of 600μm, a minor axis of 400μm, and a depth of 0.3mm.

[0053] The specific process is as follows: Pretreatment: After cleaning and drying, the glass substrate 2 is fixed on the worktable of the equipment by vacuum adsorption.

[0054] Alignment and Calibration: The vision system identifies the Mark points and imports the CAD drawing of the elliptical blind groove layout. The system automatically generates the internal filling path L1 (line spacing 2μm) and the closed contour path L2 (internal spacing 3μm). The system detects and adjusts the Z-axis so that the laser focus J of both optical paths is located 0.08mm above the lower surface 20 of the substrate.

[0055] Internal processing: Start the galvanometer scanning optical path 10, set the laser energy to the high energy range, and the scanning speed to 1000 mm / s. Quickly modify the internal region of the ellipse along the path.

[0056] Edge trimming: Automatically switch to Bessel beam shaping optical path 11, maintain the same high energy parameters and laser focus J height, scan speed 200mm / s, and perform a precise scan along the outer contour of the ellipse.

[0057] Wet etching: Immerse the glass substrate 2 in a HF / HNO3 mixture at 30°C and etch for 45 minutes with magnetic stirring.

[0058] Results: After cleaning and drying, the obtained elliptical blind grooves were tested and found to have a flat bottom (close to flat) with no serrated residue; the verticality deviation of the groove walls was ≤0.5°, and there were no chipped edges; the depth of the blind grooves was precisely controlled at 0.3mm, and the dimensional error was ≤±5μm.

[0059] As can be seen from the above embodiments, the present invention has successfully achieved efficient, high-precision, and flat-bottom forming processing of TGV blind slots through dual-optical-path coordination and a specific focusing strategy.

[0060] In another preferred embodiment of the present invention, a glass substrate 2 is also disclosed, which includes a substrate body and a TGV blind groove formed based on the glass substrate TGV blind groove processing method in the above embodiment.

[0061] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for processing TGV blind grooves on a glass substrate, characterized in that, include: A laser processing device is provided, wherein the laser processing device integrates a galvanometer scanning optical path and a Bessel beam shaping optical path; The laser focal points of both the galvanometer scanning optical path and the Bessel beam shaping optical path are focused near the lower surface of the glass substrate to be processed; Using the galvanometer scanning optical path, the internal structural region forming the blind groove is scanned according to the preset filling path to form a first modified region in the glass substrate; Using the Bessel beam shaping optical path, the edge contour area forming the blind groove is scanned according to the preset closed contour path to form a second modified region in the glass substrate. The glass substrate, after being processed by the galvanometer scanning optical path and the Bessel beam shaping optical path, is placed in an etching solution for wet etching to remove the material from the first modified region and the second modified region, forming the blind trench.

2. The method for processing TGV blind grooves on a glass substrate according to claim 1, characterized in that, The scanning speed of the galvanometer scanning optical path is 1000-1500 mm / s, and the scanning speed of the Bessel beam shaping optical path is 150-250 mm / s.

3. The method for processing TGV blind grooves on a glass substrate according to claim 1, characterized in that, The laser focus is concentrated within a range of 0.05 mm to 0.1 mm above the lower surface of the glass substrate.

4. The method for processing TGV blind grooves on a glass substrate according to claim 1, characterized in that, The preset filling path is an equally spaced line scan path, and the light emission spacing of the line scan is 1-3 μm; the spacing between the edge contour area and the internal structure area is 2-4 μm.

5. The method for processing TGV blind grooves on a glass substrate according to claim 1, characterized in that, The galvanometer scanning optical path and the Bessel beam shaping optical path are connected to the same laser source through an electric beam splitter switching mechanism.

6. The method for processing TGV blind grooves on a glass substrate according to claim 1, characterized in that, Before processing using the laser processing equipment, the method further includes identifying marker points on the surface of the glass substrate using a vision alignment system and establishing a global coordinate system to map the preset filling path and closed contour path to the target processing position of the glass substrate.

7. The method for processing TGV blind grooves on a glass substrate according to claim 1, characterized in that, Before or during processing using the laser processing equipment, the method further includes verifying the relative distance between the laser focus and the lower surface of the glass substrate using a vision system, and ensuring that the deviation of the relative distance between the laser focus and the lower surface of the glass substrate is less than or equal to a preset threshold.

8. The method for processing TGV blind grooves on a glass substrate according to claim 1, characterized in that, Magnetic stirring is used during the etching process.

9. A glass substrate, characterized in that, It includes a substrate body, on which a TGV blind groove is formed based on the glass substrate TGV blind groove processing method according to any one of claims 1 to 8.

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