Apparatus and method for improving wettability of tsv ultra-deep hole surface

Abstract

This invention discloses a device and method for improving the surface wettability of TSV (Through-Vacuum Plated) ultra-deep holes, applied in the field of through-hole electroplating and metal filling technology. The key technical points are: a wetting chamber forming a liquid processing space for accommodating a wafer; a wetting chamber cover movably disposed at the upper end of the wetting chamber for sealing and forming a sealed cavity; a waterproof cylinder fixedly connected to the outside of the wetting chamber for opening and closing the wetting chamber cover; a vacuum pump tube connected to the wetting chamber for evacuating air from the sealed cavity to establish a negative pressure environment; a wafer clamping device disposed within the wetting chamber for fixing the wafer and rotating or lifting it to ensure uniform coverage of the electroplating solution on the wafer surface; and a wetting chamber nozzle fixedly disposed at the center of the wetting chamber cover for spraying the electroplating solution onto the wafer and within the sealed cavity. The technical effect is to ensure that the solution or liquid metal can fully penetrate the bottom of the TSV ultra-deep hole and spread evenly.

Description

Technical Field

[0001] This invention relates to the field of through-hole electroplating and metal filling technology, and in particular to an apparatus and method for improving the surface wettability of TSV ultra-deep holes. Background Technology

[0002] With the rapid development of three-dimensional integrated circuits (3D ICs) and advanced packaging technologies, through-silicon via (TSV) technology has become an important means of realizing vertical interconnection of chips. TSVs achieve electrical interconnection and heat conduction between different chips or chip layers by forming micro-vias with high aspect ratios in wafers. However, due to the characteristics of TSV structures such as large depth, small aperture and smooth hole walls, it is difficult to wet the liquid in subsequent wet processing, chemical plating, electroplating and metal filling processes. Problems such as bubble residue, local dry spots and uneven plating are easy to occur, which seriously affect the density and reliability of subsequent metal filling.

[0003] In the prior art, to improve the wettability of high aspect ratio structures, Chinese invention with publication number CN105047529A discloses a method for improving the wettability of small-sized high aspect ratio structures in wet processes. This method improves the wettability of deep hole surfaces by sequentially spraying a low surface tension solution, an immersion cleaning solution, and deionized water onto the wafer surface. However, this method is mainly aimed at the cleaning stage after etching and does not take into account the synergistic effect of gas discharge from the hole and subsequent electroplating processes. In TSV structures with high aspect ratios (>10:1), there may still be a phenomenon where the liquid cannot completely enter the bottom of the hole. Additionally, Chinese invention patent CN110791746B discloses a method for rapidly filling vertical through-silicon vias (TSVs) with liquid alloy. This method involves heating the solder alloy in a vacuum environment and pressurizing it with nitrogen to complete the filling, achieving void-free TSV filling in a short time and improving filling efficiency. However, this method relies on the spreadability of the liquid metal in its high-temperature molten state, requiring extremely high wettability of the TSV via walls. If an oxide layer or residual contaminants exist on the via wall surface, the liquid metal will struggle to fully wet the bottom of the via, easily leading to voids or discontinuous interfaces. Therefore, it is necessary to propose a method and apparatus to improve the surface wettability of TSV ultra-deep holes, so as to ensure that the solution or liquid metal can fully enter the bottom of the hole and spread evenly, thereby providing a reliable interface basis for subsequent electroplating, metal filling and bonding processes. Summary of the Invention

[0004] The first objective of this invention is to provide a device for improving the surface wettability of TSV ultra-deep holes, which has the advantage of ensuring that the solution or liquid metal can fully penetrate the bottom of the TSV ultra-deep hole and spread evenly.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: an apparatus for improving the surface wettability of TSV ultra-deep holes, comprising: The wetting chamber forms a liquid processing space to accommodate the wafer; A wetting chamber cover is movably disposed at the upper end of the wetting chamber and is used to seal with the wetting chamber to form a sealed cavity; A waterproof cylinder is fixedly connected to the outside of the wetting chamber and is used to drive the wetting chamber cover to open and close. A vacuum pump tube, connected to the wetting chamber, is used to evacuate the sealed cavity to create a negative pressure environment. A wafer clamping device is disposed in the wetting chamber to fix the wafer and drive the wafer to rotate or lift, so as to ensure the uniformity of the electroplating solution coverage on the wafer surface. The wetting chamber nozzle is fixedly installed at the center of the wetting chamber cover and is used to spray electroplating solution onto the wafer and the sealed chamber.

[0006] The present invention is further configured such that: a moving ring and a baffle plate with an annular structure are provided below the wafer clamping device, which are used to prevent the electroplating liquid in the wetting chamber from seeping into the bottom of the wafer and to adjust the fluid distribution when the wafer is rotated and sprayed.

[0007] A second objective of this invention is to provide a method for improving the surface wettability of TSV ultra-deep holes, which has the advantage of ensuring that the solution or liquid metal can fully penetrate the bottom of the TSV ultra-deep hole and spread evenly.

[0008] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for improving the surface wettability of TSV ultra-deep holes, using an apparatus for improving the surface wettability of TSV ultra-deep holes as described in any of the above technical solutions; comprising: S1. Fix a semiconductor wafer onto the wafer clamping device, and rotate the wafer by the wafer clamping device; S2. The waterproof cylinder drives the wetting chamber cover to descend, thereby forming a sealed cavity with the wetting chamber. The vacuum pump tube draws the sealed cavity into a negative pressure state and discharges the residual gas in the TSV deep hole. S3. The wetting chamber nozzle sprays the electroplating solution onto the wafer surface and continues spraying for the first time. After the electroplating solution completely submerges the wafer, the spraying stops, allowing the electroplating solution to enter the TSV deep hole under the action of pressure difference. S4. Stop spraying and let the wafer stand under negative pressure for the first standing time to allow the electroplating solution to diffuse along the walls of the TSV deep holes. S5. Continue spraying the electroplating solution onto the wafer surface under negative pressure and maintain the second spraying time until the electroplating solution fills the entire sealed cavity. Use the liquid pressure formed by the electroplating solution filling the sealed cavity to push the electroplating solution into the bottom of the TSV deep hole. S6. Drain the electroplating solution from the sealed cavity, open the wetting chamber cover, and let the wafer stand under normal pressure for a second standing time to allow the electroplating solution in the TSV deep hole to spread stably.

[0009] The present invention is further configured such that: in S2, after the wetting chamber is evacuated to negative pressure by a vacuum tube pump, the pressure inside the sealed chamber is between -5300 and -5616 Pa, so as to achieve the initial wetting of the TSV deep hole.

[0010] The present invention is further configured such that: in S3, the wafer rotation speed is maintained at 20-30 rpm, and the first spraying time is 5-8 minutes.

[0011] The present invention is further configured such that: in S4, the first settling time is 1-2 minutes.

[0012] The invention is further configured such that: in S5, the wafer rotates at a speed of 10-20 rpm, and the second spraying time is 2 to 3 minutes; and after the electroplating solution fills the entire wetting chamber, the solution continues to be supplied to form a fluid pressure in the sealed chamber, which pushes the electroplating solution to penetrate into the bottom of the TSV deep hole and makes the pressure in the chamber reach -5617 Pa to -6000 Pa.

[0013] The present invention is further configured such that, in step S6, the second settling time is 3-5 minutes.

[0014] In summary, the present invention has the following beneficial effects: 1. This invention first establishes a negative pressure environment within a sealed cavity to actively extract most of the residual gas within the deep holes of the TSV. Then, under negative pressure, a rotating spray is performed to drive the electroplating solution into the pores rapidly using the pressure difference for initial wetting. Subsequently, the solution is allowed to stand under negative pressure to allow it to fully diffuse along the pore walls. Then, the solution is continuously supplied until the sealed cavity is completely filled. The incompressibility of the liquid creates a stable fluid pressure within the sealed cavity, which in turn propels the electroplating solution to further penetrate into the bottom of the TSV deep holes, thereby completely expelling any trace amounts of gas remaining at the bottom of the TSV deep holes. Finally, the solution is allowed to stand under normal pressure to ensure that the electroplating solution that has entered the deep holes spreads more evenly. This significantly improves the entry speed, wetting depth, and spreading uniformity of the electroplating solution in the TSV deep holes, providing more reliable interface conditions for subsequent electroplating, metal filling, and other processes. 2. This invention controls the pressure within the sealed cavity during the negative pressure evacuation stage between -5300 and -5616 Pa, ensuring effective gas removal from the TSV deep hole while avoiding damage to the wafer from excessive vacuum. During the negative pressure spraying stage, the wafer is rotated at 20-30 rpm and sprayed for 5-8 minutes to ensure uniform coverage of the electroplating solution on the wafer surface. Simultaneously, during the pressurized liquid supply stage, the fluid pressure within the cavity is controlled between -5617 Pa and -6000 Pa to achieve enhanced wetting of the bottom of the TSV deep hole. Finally, the wafer is allowed to stand at normal pressure for 3-5 minutes to ensure uniform and sufficient wetting of the electroplating solution, ensuring that the solution or liquid metal can fully enter the bottom of the TSV ultra-deep hole and spread evenly. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of Example 1; Figure 2 This is a cross-sectional view of the overall structure of Embodiment 1; Figure 3 This is a schematic diagram of the moving coil and the baffle plate in Example 1; Figure 4 This is a schematic diagram showing the location and shape of the TSV deep via in the wafer of Example 1; Figure 5 This is a schematic diagram of the method flow in Example 2; Figure 6 This is a schematic diagram of the wetting effect of the TSV ultra-deep hole under different negative pressure conditions in Example 2.

[0016] Reference numerals: 1. Wetting chamber; 2. Wetting chamber cover; 3. Waterproof cylinder; 4. Vacuum pump tube; 5. Wafer clamping device; 6. Wetting chamber nozzle; 7. Moving coil; 8. Water baffle. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings.

[0018] Example 1: refer to Figures 1 to 4 An apparatus for improving the surface wettability of TSV ultra-deep holes, comprising: Wetting chamber 1 forms a liquid processing space for accommodating the wafer; The wetting chamber cover 2 is movably disposed at the upper end of the wetting chamber 1 and is used to seal with the wetting chamber 1 to form a closed cavity; A waterproof cylinder 3 is fixedly connected to the outside of the wetting chamber 1 and is used to drive the wetting chamber cover 2 to open and close. A sealing structure is provided between the wetting chamber 1 and the wetting chamber cover 2. The wetting chamber 1 is opened and closed by driving the wetting chamber cover 2 to rise and fall through the waterproof cylinder 3. The vacuum pump tube 4 is connected to the wetting chamber 1 and is used to evacuate the sealed cavity to establish a negative pressure environment. A high-precision barometer is provided on the vacuum pump tube 4 to detect the vacuum level in the sealed cavity. The wafer clamping device 5 is disposed in the wetting chamber 1 and is used to fix the wafer and drive the wafer to rotate or lift, so as to ensure the uniformity of the electroplating solution coverage on the wafer surface. The wafer clamping device 5 includes a rotary drive motor and a lifting structure, thereby realizing the adjustment of the wafer rotation speed and height according to the process requirements during the wafer processing. The wetting chamber 1 nozzle is fixedly installed at the center of the wetting chamber cover 2 and is used to spray electroplating solution onto the wafer and the sealed chamber. The wetting chamber 1 nozzle is connected to an external electroplating solution supply system through pipelines. The industrial system includes a storage tank, a supply pump and a flow control valve for quantitatively supplying electroplating solution into the sealed chamber.

[0019] refer to Figure 3 Below the wafer clamping device 5, there is also a ring-shaped moving ring 7 and a water baffle 8. The moving ring 7 is fixed below the wafer clamping device 5, and the water baffle 8 is arranged around the outer periphery of the moving ring 7. Together, they form an anti-splash structure, which is used to prevent the electroplating liquid in the wetting chamber 1 from seeping into the bottom of the wafer and to adjust the fluid distribution when the wafer is rotated and sprayed, thus ensuring the consistency and reliability of the process.

[0020] Example 2: refer to Figure 5 A method for improving the surface wettability of TSV ultra-deep holes, using an apparatus for improving the surface wettability of TSV ultra-deep holes as shown in Example 1, comprising: S1. Fix a semiconductor wafer onto the wafer clamping device 5, and rotate the wafer by the wafer clamping device 5; S2. The waterproof cylinder 3 drives the wetting chamber cover 2 to descend, thereby sealing and forming a closed cavity with the wetting chamber 1. The vacuum pump tube 4 draws the closed cavity into a negative pressure state and discharges the residual gas in the TSV deep hole. Under this negative pressure environment, the original gas in the TSV deep hole is drawn out of the TSV deep hole channel due to the pressure difference, which is conducive to the subsequent entry of the electroplating solution for wetting. If the pressure in the closed cavity is too high, it is easy to cause stress damage to the wafer structure. If the negative pressure is too low, it is difficult to effectively discharge the gas at the bottom of the hole. S3. The nozzle of the wetting chamber 1 sprays the electroplating solution onto the wafer surface and continues spraying for the first time. After the electroplating solution completely submerges the wafer, the spraying stops, allowing the electroplating solution to enter the TSV deep hole under the action of pressure difference. S4. Stop spraying and let the wafer stand under negative pressure for the first standing time to allow the electroplating solution to diffuse along the walls of the TSV deep holes. S5. Continue spraying the electroplating solution onto the wafer surface under negative pressure and maintain the second spraying time until the electroplating solution fills the entire sealed cavity. The liquid pressure formed by the electroplating solution filling the sealed cavity pushes the electroplating solution to penetrate into the bottom of the TSV deep hole. During this stage, as the electroplating solution is continuously supplied, the liquid level in the sealed cavity gradually rises until it completely fills the entire cavity. The incompressibility of the liquid is used to form a stable fluid pressure in the sealed cavity, thereby pushing the electroplating solution to further penetrate into the bottom of the TSV deep hole, thereby completely expelling or compressing the residual trace gas at the bottom of the hole, thus achieving complete wetting of the deep hole. S6. Drain the electroplating solution from the sealed cavity, open the wetting chamber cover 2, and let the wafer stand under normal pressure for a second standing time to allow the electroplating solution in the TSV deep hole to spread stably.

[0021] Specifically, in S2, after the wetting chamber 1 is evacuated to negative pressure by a vacuum tube pump, the pressure inside the sealed chamber is between -5300 and -5616 Pa, so as to achieve the initial wetting of the TSV deep hole.

[0022] Specifically, in S3, the wafer rotation speed is maintained at 20-30 rpm, and the first spray time is 5-8 minutes.

[0023] Specifically, in S4, the first settling time is 1-2 minutes.

[0024] Specifically, in S5, the wafer rotates at a speed of 10-20 revolutions per minute, and the second spraying time is 2 to 3 minutes; and after the electroplating solution fills the entire wetting chamber 1, the liquid supply continues to form a fluid pressure in the sealed chamber, which pushes the electroplating solution to penetrate into the bottom of the TSV deep hole and makes the pressure in the chamber reach -5617 Pa to -6000 Pa.

[0025] Specifically, in S6, the second settling time is 3-5 minutes.

[0026] refer to Figure 6 During the first impregnation, when the pressure of the sealed cavity is maintained between -5300 and -5616 Pa, the impregnation depth does not exceed 60 μm. After the second impregnation, the fluid pressure in the sealed cavity reaches -5617 Pa, achieving complete impregnation.

[0027] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make inventive modifications to this embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A device for improving the surface wettability of TSV ultra-deep holes, characterized in that, include: Wetting chamber (1) forms a liquid processing space for accommodating the wafer; A wetting chamber cover (2) is movably disposed on the upper end of the wetting chamber (1) for sealing and fitting with the wetting chamber (1) to form a sealed cavity; A waterproof cylinder (3) is fixedly connected to the outside of the wetting chamber (1) and is used to drive the wetting chamber cover (2) to open and close. The vacuum pump tube (4) is connected to the wetting chamber (1) and is used to evacuate the sealed chamber to establish a negative pressure environment; A wafer clamping device (5) is set in the wetting chamber (1) to fix the wafer and drive the wafer to rotate or lift, so as to ensure the uniformity of the electroplating solution on the wafer surface. The wetting chamber (1) nozzle is fixedly installed at the center of the wetting chamber cover (2) and is used to spray electroplating solution onto the wafer and the sealed chamber.

2. The device for improving the surface wettability of TSV ultra-deep holes according to claim 1, characterized in that, The wafer clamping device (5) is also provided with a moving ring (7) and a baffle plate (8) in an annular structure below it, which are used to prevent the electroplating liquid in the wetting chamber (1) from seeping into the bottom of the wafer and to adjust the fluid distribution when the wafer is rotated and sprayed.

3. A method for improving the surface wettability of TSV ultra-deep holes, comprising using an apparatus for improving the surface wettability of TSV ultra-deep holes as described in any one of claims 1-2; characterized in that, include: S1. Fix a semiconductor wafer onto the wafer clamping device (5) and rotate the wafer by the wafer clamping device (5); S2, the waterproof cylinder (3) drives the wetting chamber cover (2) to descend, thereby sealing and cooperating with the wetting chamber (1) to form a closed cavity. The vacuum pump pipe (4) draws the closed cavity into a negative pressure state and discharges the residual gas in the TSV deep hole. S3, Wetting chamber (1) The nozzle sprays electroplating solution onto the wafer surface and continues for the first spraying time. After the electroplating solution completely submerges the wafer, the spraying stops, allowing the electroplating solution to enter the TSV deep hole under the action of pressure difference. S4. Stop spraying and let the wafer stand under negative pressure for the first standing time to allow the electroplating solution to diffuse along the walls of the TSV deep holes. S5. Continue spraying the electroplating solution onto the wafer surface under negative pressure and maintain the second spraying time until the electroplating solution fills the entire sealed cavity. Use the liquid pressure formed by the electroplating solution filling the sealed cavity to push the electroplating solution into the bottom of the TSV deep hole. S6. Drain the electroplating solution from the sealed cavity, open the wetting chamber cover (2), and let the wafer stand under normal pressure for a second standing time to allow the electroplating solution in the TSV deep hole to spread stably.

4. A method for improving the surface wettability of TSV ultra-deep holes according to claim 3, characterized in that, In S2, after the wetting chamber (1) is evacuated to negative pressure by a vacuum tube pump, the pressure in the sealed chamber is between -5300 and -5616 Pa, so as to achieve the initial wetting of the TSV deep hole.

5. A method for improving the surface wettability of TSV ultra-deep holes according to claim 3, characterized in that, In S3, the wafer rotation speed is maintained at 20-30 rpm, and the first spray time is 5-8 minutes.

6. The method for improving the surface wettability of TSV ultra-deep holes according to claim 3, characterized in that, In S4, the first settling time is 1-2 minutes.

7. A method for improving the surface wettability of TSV ultra-deep holes according to claim 3, characterized in that, In S5, the wafer rotates at a speed of 10-20 rpm, and the second spraying time is 2 to 3 minutes; and after the electroplating solution fills the entire wetting chamber (1), the liquid continues to be supplied to form a fluid pressure in the sealed chamber. This fluid pressure pushes the electroplating solution to penetrate into the bottom of the TSV deep hole and makes the pressure in the chamber reach -5617 Pa to -6000 Pa.

8. A method for improving the surface wettability of TSV ultra-deep holes according to claim 3, characterized in that, In S6, the second settling time is 3-5 minutes.

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