Glass through hole copper plating filling method and structure and application thereof

Abstract

The invention relates to the technical field of chip three-dimensional packaging, in particular to an efficient and void-free copper plating filling method for a glass through hole TGV, and is suitable for a metallization process of the glass through hole TGV in a high-density chip interconnection scene. According to the copper plating filling process for the glass through hole, the through hole cavity defect is overcome, the filling efficiency of the through hole is improved, meanwhile, the process compatibility is high, large-scale application is easy, the process can be adapted to filling of glass through holes of various specifications, and the copper plating filling quality and the production efficiency can be remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of chip 3D packaging technology. Specifically, it is a highly efficient, void-free copper plating filling method for glass through-hole (TGV) vias. This method is applicable to the metallization process of TGV vias in high-density chip interconnect scenarios and can significantly improve the quality of copper plating filling and production efficiency. Background Technology

[0002] With the continuous improvement of chip integration, 3D packaging technology has become a core technology direction for high-end chip packaging because it enables three-dimensional chip stacking, shortens interconnection paths, and increases packaging density. Among them, glass vias (TGV) have become an important choice for interconnection vias in 3D packaging due to the excellent electrical insulation, low dielectric loss, and matching coefficient of thermal expansion of glass with silicon wafers. The quality of copper plating in TGV directly determines the conductivity, reliability, and lifespan of chip interconnects.

[0003] Currently, copper plating filling of through-hole glass vias (TGV) mainly employs electrochemical electroplating. Its core principle is that copper ions in the plating solution migrate to the cathode within the TGV hole under the influence of an electric field, depositing a continuous copper layer on the hole wall and inside, ultimately achieving complete hole filling. However, due to the typically small pore size (mostly 5-50 μm) and large aspect ratio (generally ≥3:1) of TGVs, a significant "ion diffusion constraint" problem exists during electroplating: copper ions in the plating solution cannot diffuse quickly and uniformly to the bottom of the TGV hole, resulting in differences in copper ion concentration in different areas within the hole—the orifice area has an ample supply of copper ions, leading to rapid copper plating growth; while the bottom area experiences slow copper ion replenishment, resulting in slow copper plating growth.

[0004] To improve filling efficiency, using faster electroplating conditions, such as increasing current density, can lead to "over-deposition" in the orifice area due to rapid copper ion consumption. This can even create a "sealing" structure at the orifice, trapping unfilled voids and causing defects like voids. These voids increase interconnect resistance, cause unstable current transmission, and in severe cases, can lead to interface cracking due to differences in thermal expansion coefficients, reducing the reliability of the chip package. While using slower electroplating with lower current density can improve ion diffusion uniformity, it significantly extends the plating time, often exceeding two hours per filling cycle. This results in low production efficiency, increased costs, and difficulty in meeting the demands of large-scale mass production.

[0005] In summary, the existing glass through-hole TGV copper plating filling process faces the core bottleneck of "difficulty in balancing quality and efficiency"—fast electroplating is prone to producing voids, while slow electroplating is inefficient. There is an urgent need for a new technical solution to overcome this constraint and achieve efficient, void-free copper plating filling of glass through-hole TGV.

[0006] Therefore, it is clear that a solution is needed to address the technical problems existing in the current technology. Summary of the Invention

[0007] This invention provides a method for copper plating filling of glass through-holes and a method for three-dimensional chip packaging, which can at least solve some of the problems existing in the prior art.

[0008] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution: A method for copper plating filling of glass through-holes includes the following steps: (1) Chemically deposited copper seed layer A glass substrate with a through-hole structure is selected, and a copper seed layer is deposited on the hole wall and the surface of the glass substrate using a chemical copper plating process. (2) Pulsed laser-assisted electroplating deposition of copper filler layer S21: Immerse the glass substrate with the deposited copper seed layer in the electroplating solution, and slowly deposit the initial copper layer at the opening and bottom of the through hole under the first current density condition. S22: When the initial copper layer is deposited to the preset thickness and / or preset time, the pulsed laser is turned on to intermittently irradiate the through hole, and the electroplating current density and pulsed laser energy are dynamically adjusted until the through hole is completely filled with copper layer.

[0009] As a preferred embodiment of the copper plating filling method for glass through-holes according to the present invention, the method further includes a pretreatment step and an activation treatment step for the glass substrate before chemically depositing a copper seed layer.

[0010] As a preferred embodiment of the copper plating filling method for glass through holes according to the present invention, the pretreatment method is to immerse the glass substrate in a 5-10% dilute sulfuric acid solution for cleaning for 10-15 minutes, followed by ultrasonic cleaning with deionized water 3-5 times until the pH of the rinsing solution is neutral.

[0011] As a preferred embodiment of the copper plating filling method for glass through holes according to the present invention, the activation treatment step is to immerse the pretreated glass substrate in a 0.1-0.5 g / L palladium salt activation solution for 5-10 min.

[0012] As a preferred embodiment of the copper plating filling method for glass through holes according to the present invention, a surface smoothing treatment step is further included after pulsed laser-assisted electroplating deposition of the copper plating filling layer.

[0013] As a preferred embodiment of the copper plating filling method for glass through holes according to the present invention, the surface planarization step is to polish the excess copper layer on the surface of the glass substrate using a chemical mechanical polishing process.

[0014] As a preferred embodiment of the copper plating filling method for glass through holes described in this invention, the residual copper layer after polishing has a thickness of 5-10 μm and is flush with the surface of the glass substrate.

[0015] As a preferred embodiment of the copper plating filling method for glass through holes described in this invention, the method further includes rinsing the surface of residual electroplating solution with deionized water before surface leveling treatment, followed by placing the surface in a vacuum drying oven and drying it at a temperature of 60-80°C for 15-30 minutes with a vacuum degree of -0.08 to -0.09 MPa.

[0016] As a preferred embodiment of the copper plating filling method for glass through holes according to the present invention, the through hole diameter of the glass substrate is 5-50μm and the depth-to-diameter ratio is (3-10):1.

[0017] As a preferred embodiment of the copper plating filling method for glass through holes described in this invention, the thickness of the copper seed layer in step (1) is 0.5-3 μm.

[0018] As a preferred embodiment of the copper plating filling method for glass through holes described in this invention, the chemical copper plating process uses formaldehyde as a catalyst, the reaction temperature is 30-50℃, and the time is 15-30 min.

[0019] As a preferred embodiment of the copper plating filling method for glass through holes described in this invention, wherein: the electroplating deposition process in step (2) adopts an acidic copper plating system, and the composition of the electroplating solution is: 200-250 g / L copper sulfate, 5-8 g / L sulfuric acid, 5-10 mg / L chloride ions, 0.1-0.5 mL / L brightener, 0.5-2 mL / L leveling agent, the temperature of the electroplating solution is 25-30℃, and the stirring rate is 100-200 r / min.

[0020] As a preferred embodiment of the copper plating filling method for glass through holes according to the present invention, in step S21, the initial electroplating current density is 1-2 A / dm², the electroplating time is 10-15 min, and the initial copper layer thickness is 1-3 μm.

[0021] As a preferred embodiment of the copper plating filling method for glass through-holes according to the present invention, in step S22, the pulse width of the pulsed laser is 10-100 fs, the wavelength is 532-1064 nm, the diameter of the focused spot is 1 / 3-1 / 2 of the TGV aperture, and the initial laser parameters are: repetition frequency is 1-10 kHz, single pulse energy is 1-5 mJ, and the irradiation mode is intermittent irradiation with an interval of 2-8 seconds after irradiation for 1-5 seconds.

[0022] As a preferred embodiment of the copper plating filling method for glass through holes according to the present invention, the method of dynamically adjusting the electroplating current density and pulsed laser energy in step S22 is as follows: when the plating layer fills to 1 / 3-1 / 2 of the hole depth, the current density is increased to 2-4 A / dm², and when the plating layer fills to 3 / 5-3 / 4 of the hole depth, the laser single pulse energy is reduced to 0.5-2 mJ.

[0023] To address the aforementioned technical problems, according to another aspect of the present invention, the present invention provides the following technical solution: A TGV structure obtained by a copper plating filling method for glass through-holes, wherein the copper plating filling void ratio of the TGV is ≤0.1%, the interconnect resistance is ≤10mΩ, and the resistance change rate is ≤3% after 1000 thermal cycles in the range of -55℃ to 125℃.

[0024] Application of TGV structure obtained by a copper plating filling method for glass through-holes in chip 3D packaging.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The copper plating filling method for glass through-holes of the present invention solves the defect problem of voids in through-holes and improves the filling quality. The present invention uses selective focusing of pulsed laser to precisely apply energy to the region inside the TGV hole, using the photothermal effect to accelerate the diffusion of copper ions to the bottom of the hole, while activating the deposition activity inside the hole, avoiding the formation of a seal at the hole opening due to "over-deposition", fundamentally solving the void defect caused by rapid electroplating. Tests have shown that the void rate of TGV copper plating filling can be reduced to below 0.1%.

[0026] 2. The copper plating filling method for glass through-holes of the present invention improves the filling efficiency of TGV through-holes and reduces costs. With the assistance of pulsed laser, the electroplating current density can be increased to 1.5-2 times that of the traditional process, and the single TGV copper plating filling cycle is shortened from more than 2 hours to 40-60 minutes, increasing production efficiency by more than 60% and significantly reducing time and energy costs.

[0027] 3. The copper plating filling method for glass through holes of the present invention has strong process compatibility and is easy to scale up. The acidic copper plating system and pulsed laser device used are existing industrial equipment, which do not require large-scale modification of traditional electroplating production lines. Only the addition of a laser focusing and positioning module is needed to achieve compatibility with existing production lines, which facilitates large-scale mass production and promotion.

[0028] 4. The copper plating filling method for glass through-holes of the present invention has wide process applicability and is suitable for different TGV specifications. By adjusting the focused spot of the pulsed laser, the single pulse energy, and the electroplating parameters, it can be adapted to different specifications of TGV with apertures of 5-50μm and aspect ratios of 3-10:1, solving the problem that traditional processes require re-optimization of parameters for different specifications of TGV, and improving process flexibility. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0030] Figure 1 This is a flowchart of the copper plating filling process for glass through-holes in this invention. Detailed Implementation

[0031] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0033] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0034] This invention provides a copper plating filling method for glass through-holes and a chip three-dimensional packaging method. The copper plating filling process for glass through-holes solves the void defect of through-holes, improves the filling efficiency of through-holes, and has strong process compatibility, is easy to scale up and apply, and can be adapted to the filling of glass through-holes of various specifications, which can significantly improve the copper plating filling quality and production efficiency.

[0035] like Figure 1 As shown, a method for copper plating filling of glass through-holes includes the following steps: (1) Chemically deposited copper seed layer A glass substrate with a through-hole structure is selected, and a copper seed layer is deposited on the hole wall and the surface of the glass substrate using a chemical copper plating process. (2) Pulsed laser-assisted electroplating deposition of copper filler layer S21: Immerse the glass substrate with the deposited copper seed layer in the electroplating solution, and slowly deposit the initial copper layer at the opening and bottom of the through hole under the first current density condition. S22: When the initial copper layer is deposited to the preset thickness and / or preset time, the pulsed laser is turned on to intermittently irradiate the through hole, and the electroplating current density and pulsed laser energy are dynamically adjusted until the through hole is completely filled with copper layer.

[0036] Preferably, the process includes a pretreatment step and an activation step on the glass substrate before chemically depositing the copper seed layer.

[0037] Preferably, the pretreatment method involves immersing the glass substrate in a 5-10% dilute sulfuric acid solution for 10-15 minutes, followed by ultrasonic cleaning with deionized water 3-5 times until the pH of the rinsing solution is neutral. The purpose of cleaning is to remove oxide impurities from the inner surface of the pore walls, which can effectively improve the adhesion between the subsequent film layer and the substrate.

[0038] Preferably, the activation step involves immersing the pretreated glass substrate in a 0.1-0.5 g / L palladium salt activation solution for 5-10 minutes. The activation process adsorbs palladium particles onto the pore wall surface, achieving a catalytic activation effect.

[0039] Preferably, after pulsed laser-assisted electroplating to deposit the copper filler layer, a surface planarization step is also included.

[0040] Preferably, the surface planarization step involves polishing the excess copper layer on the glass substrate surface using a chemical mechanical polishing process.

[0041] Preferably, the residual copper layer after polishing is 5-10 μm thick and flush with the surface of the glass substrate.

[0042] Preferably, before surface smoothing treatment, the surface is rinsed with deionized water to remove residual electroplating solution, and then placed in a vacuum drying oven and dried at a temperature of 60-80°C for 15-30 minutes with a vacuum degree of -0.08 to -0.09 MPa.

[0043] Preferably, the aperture of the through hole in the glass substrate is 5-50 μm and the aspect ratio is (3-10):1.

[0044] Preferably, the thickness of the copper seed layer in step (1) is 0.5-3μm. The uniform copper seed layer can serve as a metal layer to ensure that the current is uniformly and stably conducted into the glass through hole during the subsequent electroplating process, thereby achieving uniform electroplating deposition in all parts of the inner wall of the through hole.

[0045] Preferably, the chemical copper plating process uses formaldehyde as a catalyst, the reaction temperature is 30-50℃, and the time is 15-30 min.

[0046] Preferably, in step (2), a glass substrate with a copper seed layer is used as the cathode in the electroplating process and connected to the negative electrode of the electroplating. A pure copper plate with a purity of not less than 99.99% is selected as the anode and connected to the positive electrode of the electroplating power supply. The relative positions of the cathode and anode are adjusted so that the through-hole area of ​​the glass substrate is completely immersed in the electroplating solution and is kept at a distance of 5-10 cm from the anode.

[0047] Preferably, the electroplating deposition process in step (2) adopts an acidic copper plating system, and the electroplating solution composition is: 200-250 g / L copper sulfate, 5-8 g / L sulfuric acid, 5-10 mg / L chloride ions, 0.1-0.5 mL / L brightener, 0.5-2 mL / L leveling agent, electroplating solution temperature 25-30℃, and stirring rate 100-200 r / min.

[0048] Preferably, in step S21, the initial electroplating current density is 1-2 A / dm², the electroplating time is 10-15 min, and the initial copper layer thickness is 1-3 μm.

[0049] Preferably, in step S22, the pulse width of the pulsed laser is 10-100 fs, the wavelength is 532-1064 nm, and the focal length is 50-200 mm; the diameter of the focused spot is 1 / 3-1 / 2 of the TGV aperture; the initial laser parameters are: repetition frequency of 1-10 kHz, single pulse energy of 1-5 mJ, and irradiation mode of intermittent irradiation with an interval of 2-8 seconds after irradiation for 1-5 seconds.

[0050] Preferably, when the initial copper layer thickness reaches 1-3 μm, the pulsed laser is turned on, and the through hole is intermittently irradiated according to preset parameters. During the laser irradiation process, the photothermal and photochemical effects of the pulsed laser can, on the one hand, locally increase the temperature of the electroplating solution in the through hole and accelerate the diffusion rate of copper ions; on the other hand, the laser irradiation can also activate the deposition activity of copper ions in the hole, promote the uniform deposition of copper ions at the bottom and sidewalls of the through hole, and improve the growth rate of copper plating in the through hole at specific points.

[0051] Preferably, the pulsed laser is aligned with the opening of the through hole by a visual positioning system, such as a CCD camera, and the optical focusing system is adjusted so that the laser beam is precisely focused on the surface of the copper seed layer inside the through hole, thereby ensuring that the laser beam energy can be concentrated on the area inside the hole.

[0052] Preferably, the dynamic adjustment of the electroplating current density and pulsed laser energy in step S22 is as follows: when the plating layer fills to 1 / 3-1 / 2 of the hole depth, the current density is increased to 2-4 A / dm², while maintaining intermittent pulsed laser irradiation; when the plating layer fills to 3 / 5-3 / 4 of the hole depth, the single-pulse laser energy is reduced to 0.5-2 mJ. Appropriately reducing the energy density of the pulsed laser can avoid excessive deposition at the hole opening, which could cause blockage. When the via is completely filled with copper, the power supply to the pulsed laser device and the electroplating device is turned off. The filling status of the copper layer can be detected by visual inspection or resistance detection.

[0053] A TGV structure obtained by a copper plating filling method for glass through-holes, wherein the copper plating filling void ratio of the TGV is ≤0.1%, the interconnect resistance is ≤10mΩ, and the resistance change rate is ≤3% after 1000 thermal cycles in the range of -55℃ to 125℃.

[0054] Application of TGV structure obtained by a copper plating filling method for glass through-holes in chip 3D packaging.

[0055] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0056] Example 1 1. Glass substrate pretreatment (1) Hole wall cleaning: Select a borosilicate glass substrate with a size of 100mm×100mm. The surface of the glass substrate has through holes with a diameter of 20μm, a hole density of 100 holes / mm², and a depth-to-diameter ratio of 8:1. Soak the glass substrate in a dilute sulfuric acid solution with a concentration of 8% for 12 minutes, and rinse it with deionized water 4 times until the pH of the rinsing water is neutral. (2) Activation and seed layer preparation: The glass substrate was immersed in 0.3 g / L palladium chloride activation solution for 7 min, and then chemical copper plating process was adopted. Formaldehyde was used as a reducing agent in the chemical copper plating solution. The deposition temperature was 35℃ and the time was 20 min. A 1 μm thick copper seed layer was deposited on the hole wall and surface. The seed layer was found to have good continuity and no breaks.

[0057] 2. Electroplating system setup and pulsed laser device debugging (1) Electroplating tank configuration: The electroplating solution consists of 220 g / L copper sulfate, 6 g / L sulfuric acid, 8 mg / L chloride ions, 0.3 mL / L sodium polydisulfide dipropane sulfonate, and 1 mL / L benzyl acetone. After being injected into the electroplating tank, the temperature is controlled at 28℃ and the stirring rate is 150 r / min. (2) Electrode connection: The glass substrate is used as the cathode and connected to the negative electrode of the electroplating power supply. Pure copper is used as the anode. The anode size is 120mm×120mm×5mm. The anode is connected to the positive electrode. The two electrodes are parallel and the distance between them is 8cm. The through-hole area is completely immersed in the electroplating solution. (3) Pulse laser device debugging: Select a femtosecond pulse laser (pulse width 15fs, wavelength 532nm) and a focusing lens with a focal length of 100mm; position the through hole of the glass substrate through the CCD camera, adjust the diameter of the focused spot to 8μm, and align it with the seed layer inside the hole; set the laser parameters: repetition frequency 5kHz, single pulse energy 3mJ, irradiation time 3s, and interval time 5s.

[0058] 3. Pulsed laser-assisted TGV copper plating filler (1) Initial electroplating start-up: Turn on the electroplating power supply, with an initial current density of 1.5A / dm², electroplat for 12 minutes to form an initial copper layer with a thickness of 2μm; (2) Pulsed laser point acceleration: Turn on the pulsed laser and intermittently irradiate the hole of the glass through hole according to the preset parameters; after 30 minutes, when the hole of the glass substrate is filled to 1 / 3 of the hole depth, increase the current density to 3A / dm² and continue electroplating; when it is filled to 3 / 5 of the hole depth, reduce the laser single pulse energy to 1.5mJ. (3) Filling completion test: When the total electroplating time is 50 min, observe with a metallographic microscope that the copper layer inside the through hole is completely filled and there are no obvious gaps. Then turn off the laser and power supply.

[0059] 4. Post-processing (1) Cleaning and drying: Take out the glass substrate, rinse with deionized water, and then vacuum dry at 70°C for 18 min; (2) Surface smoothing: CMP process is used for surface polishing. The polishing pressure is 10 kPa, the rotation speed is 60 r / min, the polishing liquid is silica slurry, and the copper layer thickness on the surface after polishing is 8 μm, which is flush with the glass surface.

[0060] Testing revealed that the void ratio of the TGV copper plating was 0.05%, the interconnect resistance was ≤5mΩ, and after 1000 cycles of thermal cycling (-55℃ to 125℃), the resistance change rate was ≤3%, meeting the reliability requirements of chip 3D packaging.

[0061] Example 2 1. Glass substrate pretreatment (1) Hole wall cleaning: Select a borosilicate glass substrate with a size of 100mm×100mm. The surface of the glass substrate has through holes with a diameter of 16μm, the hole density is 120 holes / mm², and the depth-to-diameter ratio of the through holes on the glass substrate is 10:1. Soak the glass substrate in a 9% dilute sulfuric acid solution for 12 minutes, and rinse it with deionized water 5 times until the pH of the rinsing water is neutral. (2) Activation and seed layer preparation: The glass substrate was immersed in 0.2 g / L palladium chloride activation solution for 10 min, and then chemical copper plating process was adopted. Formaldehyde was used as a reducing agent in the chemical copper plating solution. The deposition temperature was 35℃ and the time was 25 min. A copper seed layer with a thickness of 0.8 μm was deposited on the hole wall and surface. The seed layer was found to have good continuity and no breaks.

[0062] 2. Electroplating system setup and pulsed laser device debugging (1) Electroplating tank configuration: The electroplating solution consists of 200 g / L copper sulfate, 6 g / L sulfuric acid, 6 mg / L chloride ions, 0.2 mL / L sodium polydisulfide dipropane sulfonate, and 0.8 mL / L benzyl acetone. After being injected into the electroplating tank, the temperature is controlled at 30℃ and the stirring rate is 160 r / min. (2) Electrode connection: The glass substrate is used as the cathode and connected to the negative electrode of the electroplating power supply. Pure copper is used as the anode. The anode size is 120mm×120mm×5mm. The anode is connected to the positive electrode. The two electrodes are parallel and the distance between them is 8cm. The through-hole area is completely immersed in the electroplating solution. (3) Pulse laser device debugging: Select a femtosecond pulse laser (pulse width 15fs, wavelength 532nm) and a focusing lens with a focal length of 80mm; position the through hole of the glass substrate through the CCD camera, adjust the diameter of the focused spot to 8μm, and align it with the seed layer inside the hole; set the laser parameters: repetition frequency 3kHz, single pulse energy 2mJ, irradiation time 3s, and interval time 4s.

[0063] 3. Pulsed laser-assisted TGV copper plating filler (1) Initial electroplating start-up: Turn on the electroplating power supply, with an initial current density of 1.0 A / dm², electroplat for 15 min to form an initial copper layer with a thickness of 2 μm; (2) Pulsed laser point acceleration: Turn on the pulsed laser and intermittently irradiate the hole of the glass through hole according to the preset parameters; when the hole of the glass substrate is filled to 2 / 5 of the hole depth, increase the current density to 3.5A / dm² and continue electroplating; when it is filled to 3 / 4 of the hole depth, reduce the laser single pulse energy to 1.0mJ. (3) Filling completion test: When the total electroplating time is 45 min, observe with a metallographic microscope that the copper layer inside the through hole is completely filled and there are no obvious gaps. Then turn off the laser and power supply.

[0064] 4. Post-processing (1) Cleaning and drying: Take out the glass substrate, rinse with deionized water, and then vacuum dry at 70°C for 20 min; (2) Surface smoothing: CMP process is used for surface polishing. The polishing pressure is 10 kPa, the rotation speed is 60 r / min, the polishing liquid is silica slurry, and the copper layer thickness on the surface after polishing is 6 μm, which is flush with the glass surface.

[0065] Testing revealed that the void ratio of the TGV copper plating was 0.08%, the interconnect resistance was ≤6mΩ, and after 1000 cycles of thermal cycling (-55℃ to 125℃), the resistance change rate was ≤3%, meeting the reliability requirements of chip 3D packaging.

[0066] Example 3 1. Glass substrate pretreatment (1) Hole wall cleaning: Select a borosilicate glass substrate with a size of 100mm×100mm. The surface of the glass substrate has through holes with a diameter of 40μm, a hole density of 60 holes / mm², and a depth-to-diameter ratio of 4:1 for the through holes. Soak the glass substrate in a 10% dilute sulfuric acid solution for 10 minutes, and rinse it with deionized water 5 times until the pH of the rinsing water is neutral. (2) Activation and seed layer preparation: The glass substrate was immersed in 0.5 g / L palladium chloride activation solution for 9 min, and then chemical copper plating process was adopted. Formaldehyde was used as a reducing agent in the chemical copper plating solution. The deposition temperature was 45℃ and the time was 25 min. A copper seed layer with a thickness of 1.8 μm was deposited on the hole wall and surface. The seed layer was found to have good continuity and no breaks.

[0067] 2. Electroplating system setup and pulsed laser device debugging (1) Electroplating tank configuration: The electroplating solution consists of 250 g / L copper sulfate, 8 g / L sulfuric acid, 9 mg / L chloride ions, 0.4 mL / L sodium polydisulfide dipropane sulfonate, and 1.5 mL / L benzyl acetone. After being injected into the electroplating tank, the temperature is controlled at 30℃ and the stirring rate is 180 r / min. (2) Electrode connection: The glass substrate is used as the cathode and connected to the negative electrode of the electroplating power supply. Pure copper is used as the anode. The anode size is 120mm×120mm×5mm. The anode is connected to the positive electrode. The two electrodes are parallel and the distance between them is 10cm. The through-hole area is completely immersed in the electroplating solution. (3) Pulse laser device debugging: Select a femtosecond pulse laser (pulse width 15fs, wavelength 532nm) and a focusing lens with a focal length of 100mm; position the through hole of the glass substrate through the CCD camera, adjust the diameter of the focused spot to 8μm, and align it with the seed layer inside the hole; set the laser parameters: repetition frequency 8kHz, single pulse energy 5mJ, irradiation time 4s, and interval time 6s.

[0068] 3. Pulsed laser-assisted TGV copper plating filler (1) Initial electroplating start-up: Turn on the electroplating power supply, with an initial current density of 1.8A / dm², electroplat for 15 minutes to form an initial copper layer with a thickness of 2.4μm; (2) Pulsed laser point acceleration: Turn on the pulsed laser and intermittently irradiate the hole of the glass through hole according to the preset parameters; when the hole of the glass substrate is filled to 2 / 5 of the hole depth, the current density is increased to 3.6A / dm² and electroplating continues; when it is filled to 3 / 4 of the hole depth, the laser single pulse energy is reduced to 2.0mJ. (3) Filling completion test: When the total electroplating time is 45 min, observe with a metallographic microscope that the copper layer inside the through hole is completely filled and there are no obvious gaps. Then turn off the laser and power supply.

[0069] 4. Post-processing (1) Cleaning and drying: Take out the glass substrate, rinse with deionized water, and then vacuum dry at 70°C for 18 min; (2) Surface smoothing: CMP process is used for surface polishing. The polishing pressure is 10 kPa, the rotation speed is 60 r / min, the polishing liquid is silica slurry, and the copper layer thickness on the surface after polishing is 8 μm, which is flush with the glass surface.

[0070] Testing revealed that the void ratio of the TGV copper plating was 0.06%, the interconnect resistance was ≤5mΩ, and after 1000 cycles of thermal cycling (-55℃ to 125℃), the resistance change rate was ≤3%, meeting the reliability requirements of chip 3D packaging.

[0071] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

[0072] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for copper plating filling of glass through holes, characterized in that, The copper plating filling method for glass through-holes includes the following steps: (1) Chemically deposited copper seed layer A glass substrate with a through-hole structure is selected, and a copper seed layer is deposited on the hole wall and the surface of the glass substrate using a chemical copper plating process. (2) Pulsed laser-assisted electroplating deposition of copper filler layer S21: Immerse the glass substrate with the deposited copper seed layer in the electroplating solution, and slowly deposit the initial copper layer at the opening and bottom of the through hole under the first current density condition. S22: When the initial copper layer is deposited to the preset thickness and / or preset time, the pulsed laser is turned on to intermittently irradiate the through hole, and the electroplating current density and pulsed laser energy are dynamically adjusted until the through hole is completely filled with copper layer.

2. The method for copper plating filling of glass through holes according to claim 1, characterized in that, Before the chemical deposition of the copper seed layer, the process includes a pretreatment step and an activation step for the glass substrate. The process includes a surface smoothing step after the copper filler layer is deposited by pulsed laser-assisted electroplating and / or electroplating.

3. The method for copper plating filling of glass through holes according to claim 1, characterized in that, The aperture of the glass substrate is 5-50μm, and the depth-to-diameter ratio is (3-10):

1.

4. The method for copper plating filling of glass through holes according to claim 1, characterized in that, The thickness of the copper seed layer in step (1) is 0.5-3 μm; The copper plating process and / or chemical plating uses formaldehyde as a catalyst, with a reaction temperature of 30-50℃ and a reaction time of 15-30 min.

5. The method for copper plating filling of glass through holes according to claim 1, characterized in that, The electroplating deposition process in step (2) adopts an acidic copper plating system. The electroplating solution consists of: 200-250 g / L copper sulfate, 5-8 g / L sulfuric acid, 5-10 mg / L chloride ions, 0.1-0.5 mL / L brightener, and 0.5-2 mL / L leveling agent. The electroplating solution temperature is 25-30℃, and the stirring rate is 100-200 r / min.

6. The method for copper plating filling of glass through holes according to claim 1, characterized in that, In step S21, the initial electroplating current density is 1-2 A / dm², the electroplating time is 10-15 min, and the initial copper layer thickness is 1-3 μm.

7. The method for copper plating filling of glass through holes according to claim 1, characterized in that, In step S22, the pulse width of the pulsed laser is 10-100 fs, the wavelength is 532-1064 nm, and the focused spot diameter is 1 / 3-1 / 2 of the TGV aperture. The initial laser parameters are: repetition frequency of 1-10 kHz, single pulse energy of 1-5 mJ, and irradiation mode of irradiation for 1-5 s with an interval of 2-8 s.

8. The method for copper plating filling of glass through holes according to claim 7, characterized in that, The method for dynamically adjusting the electroplating current density and pulsed laser energy in step S22 is as follows: when the coating fills to 1 / 3-1 / 2 of the hole depth, the current density is increased to 2-4 A / dm², and when the coating fills to 3 / 5-3 / 4 of the hole depth, the laser single pulse energy is reduced to 0.5-2 mJ.

9. The TGV structure obtained by the copper plating filling method for glass through-holes according to any one of claims 1-8, characterized in that, The TGV has a copper plating filling void ratio of ≤0.1% and an interconnect resistance of ≤10mΩ; after 1000 cycles of thermal cycling in the range of -55℃ to 125℃, the resistance change rate is ≤3%.

10. The application of the TGV structure according to claim 9 in three-dimensional chip packaging.

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