A sputtering system based on coil inductive coupling assistance

Abstract

The application belongs to the technical field of semiconductor packaging, and particularly relates to a sputtering system based on coil inductive coupling assistance. The sputtering system comprises a vacuum chamber, a substrate arranged in the vacuum chamber, four inclined circumferential plane magnetron targets arranged on the substrate in the vacuum chamber, and two cylindrical magnetron targets arranged at the central axis of the cavity of the vacuum chamber, and four induction coils are arranged in the cavity of the vacuum chamber to form an inductive coupling electric field with the cylindrical magnetron targets. The application improves the uniformity of the plane film thickness.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor packaging technology, specifically relating to a sputtering system based on coil inductive coupling assistance. Background Technology

[0002] With the rapid advancement of high-density semiconductor packaging and 3D chip stacking technologies, through-glass vias (TGVs) are widely used in advanced packaging modules, optoelectronic sensing components, and high-frequency antennas. To achieve electrical conductivity within the via and support subsequent electroplating and via-filling processes, a continuous and low-resistance metal seed layer needs to be formed on the inner wall and bottom of the glass via.

[0003] Currently, the mainstream production line practice is to use magnetron sputtering, a technique within physical vapor deposition (PVD), to form a continuous film layer on the substrate surface using copper or tantalum as the target material. However, for TGV structures with high aspect ratios (>8:1), traditional sputtering systems face significant technical bottlenecks:

[0004] 1. Insufficient penetration into the hole (lower single-sided coating step coverage SC% and double-sided coating step coverage DSC%): Metal particles with a unidirectional incident angle have difficulty penetrating deep into the hole, resulting in the inability to form a continuous coating on the sidewalls and bottom.

[0005] 2. Poor uniformity of film thickness in planar areas (high U%): Uneven incident target particles can easily cause excessive differences in film thickness between the center and the edge, affecting the overall quality.

[0006] 3. Limited plasma density and low film formation efficiency: Especially under conditions of non-heated substrates or large-area substrates, ion activation is insufficient and the film is porous.

[0007] To overcome the above difficulties, it is crucial to develop a new sputtering system that can effectively improve deep-hole sputtering capability, thin film uniformity, and deposition efficiency.

[0008] Based on this motivation, the present invention proposes a new sputtering system. Summary of the Invention

[0009] To address the significant technical bottleneck of traditional sputtering systems—poor uniformity of planar film thickness (high U%)—this invention proposes a composite sputtering system based on coil inductive coupling, integrating a planar magnetron target, a cylindrical magnetron target, and coil-coupled assisted plasma.

[0010] This invention provides the following technical solution:

[0011] A sputtering system based on coil inductive coupling assistance includes a vacuum chamber, a substrate disposed in the vacuum chamber, four inclined surrounding planar magnetron targets disposed on the substrate in the vacuum chamber, and two cylindrical magnetron targets disposed at the central axis of the vacuum chamber cavity. Four induction coils are disposed in the cavity of the vacuum chamber to form an inductively coupled electric field with the cylindrical magnetron targets.

[0012] Furthermore, an induction coil is provided between adjacent planar magnetically controlled targets.

[0013] Furthermore, it also includes a high-frequency power supply located at the top of the vacuum chamber.

[0014] Furthermore, the high-frequency power supply employs a 13.56MHz high-frequency source.

[0015] Furthermore, it is equipped with four 8-12 inch planar magnetron sputtering targets.

[0016] Furthermore, four planar magnetron targets are arranged around the outer edge of the substrate.

[0017] Furthermore, the four planar magnetron targets are tilted inward at γ angles of 20° to 45°.

[0018] Furthermore, the cylindrical magnetron target adopts a 6-inch vertical layout.

[0019] Furthermore, the target-to-substrate distance (TSD) of the cylindrical magnetron target is set to 90~150 mm.

[0020] Furthermore, the substrate rotation speed is 20~30 RPM.

[0021] Furthermore, the air pressure inside the vacuum chamber is 2~30 mtorr.

[0022] Furthermore, the power of the planar magnetron target is 4~6 W / cm², the power of the cylindrical magnetron target is 6~10 KW / M, and the power of the induction coil is 400~800 W.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] Combined target source design: This composite sputtering system integrates four tilted planar magnetron targets and two vertical cylindrical magnetron targets, coupled with four induction coils to assist plasma, providing multi-angle sputtering sources. It can perform high-quality film deposition in different orientations within TGV holes, achieving a seed layer deposition process with high uniformity and high penetration, meeting the special needs of current packaging and advanced manufacturing.

[0025] Inductively coupled plasma-assisted deposition: High-frequency power supply is used to excite uniform high-density plasma, which improves particle energy and activation efficiency, enhances deposition rate and film density, and provides effective plasma support for in-hole coating.

[0026] High uniformity design: This system can achieve a film thickness distribution with a uniformity U% of less than 1.1% in a plane. Experiments have shown that the single-sided coating step coverage SC% and double-sided coating step coverage DSC% in the hole are significantly better than existing equipment, and no additional heating or long-term processing is required.

[0027] Dynamic scanning control: The target and magnetic field can be scanned and controlled. Combined with substrate rotation, a 360-degree isotropic deposition effect can be achieved.

[0028] In-hole coating optimization: The central cylindrical magnetron target is designed for deep holes, and the coil enhances the efficiency of particle entry into the hole, ensuring complete coating, especially for holes with a depth ratio greater than 8:1.

[0029] Easy to implement in production lines: This technology can be directly integrated into existing PVD equipment platforms. Both the target and plasma modules are modularly designed, making it easy to adjust and upgrade.

[0030] High application value: Possessing dual capabilities of large-area uniform deposition and deep-hole coating, it is particularly suitable for high-frequency, high-reliability TGV / TSV wafer structures and advanced packaging modules. This invention is the first to combine inductively coupled plasma (ICP)-assisted technology with cylindrical magnetron targets in a multi-target magnetron sputtering system, balancing planar and deep-hole coating performance to improve plasma density and reaction efficiency. With dynamic multi-target configuration, it has the potential to overcome the limitations of traditional PVD and achieve complete coating coverage of high aspect ratio TGV structures.

[0031] Significantly improved penetration performance: The double-sided coating has a step coverage rate (DSC%) of over 5%, which is significantly better than traditional systems, solving the problem that high aspect ratio TGV cannot be completely covered.

[0032] Modular and flexible adjustment: The angle of each target, the target-to-base distance (TSD), and the power can be adjusted independently, providing flexibility for mass production.

[0033] High process stability: The plasma is stable and the deposition rate is high, which can shorten the coating time and improve the yield.

[0034] This invention has wide applications and is suitable for the following scenarios:

[0035] 1) Through-hole metallization / seed layer: Adhesion / blocking / seed layer for through-holes of TGV / TSV, ceramic or packaging substrates (such as Cu, Ti, Cr, W, Ta / TaN, TiN, etc.), especially suitable for high aspect ratio (≥8:1) structures.

[0036] 2) Large-area glass and optoelectronics: deposition of ITO, reflective / blocking / conductive multilayers (including MAM, etc.), requiring small in-plane color difference / thickness U% and coverage of openings / micro-grooves.

[0037] 3) Microstructure / microchannel devices: Metallized or functional films with three-dimensional structures such as micropores, microgrooves, and microbump arrays require near-normal incident and sidewall compensation.

[0038] 4) Reactivity and composite films: Low-pressure, high-density deposition of oxide, nitride and metal / dielectric composite films reduces redeposition and compositional drift.

[0039] 5) Pre- and post-treatment aids: pre-sputtering desorption / water removal, ion cleaning; after film formation, a thin capping layer is added to resist roughening and stabilize electrical properties.

[0040] 6) Mass production integration: compatible with single-wafer / batch, linear or ring transport platforms; high utilization of cylindrical magnetron targets, suitable for long-cycle continuous production and low-temperature sensitive substrates; helps reduce unit area cost and improve the electrical continuity and consistency of vias. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the sputtering system structure of the present invention, with the induction coil omitted;

[0042] Figure 2 for Figure 1 The right view;

[0043] Figure 3 for Figure 1 Top view;

[0044] Figure 4 This is a schematic diagram of the target configuration of the present invention;

[0045] Figure 5 This is a simplified distribution diagram of the planar magnetron target, cylindrical magnetron target, and induction coil in the sputtering system of the present invention;

[0046] Figure 6 This is a single-sided film thickness distribution diagram inside the hole of the present invention (9:1 TGV hole, diameter 35 µm, depth 300 µm).

[0047] Figure 7 This is a single-sided film thickness distribution diagram inside the hole of the present invention (2:1 TGV hole, diameter 5 µm, depth 10 µm).

[0048] Figure 8 This is a planar film thickness distribution diagram of the present invention (9:1 TGV aperture, diameter 35 µm, depth 300 µm). Figure 9 This is a planar film thickness distribution diagram of the present invention (2:1 TGV hole, diameter 5 µm, depth 10 µm).

[0049] Figure label:

[0050] 1. Vacuum chamber; 11. Vacuum chamber entrance; 2. Substrate; 3. Planar magnetron target; 4. Cylindrical magnetron target; 5. High-frequency power supply. Detailed Implementation

[0051] The technical solution of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0052] It should be noted that the terms "center", "upper", "lower", "horizontal", "left", "right", "front", "rear", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0053] Example

[0054] Combination Figures 1-3 As shown, the present invention provides a sputtering system based on coil inductive coupling, including a vacuum chamber 1, a substrate 2 disposed in the vacuum chamber 1, four inclined surrounding planar magnetron targets 3 disposed on the substrate 2 in the vacuum chamber 1, and two cylindrical magnetron targets 4 disposed at the central axis of the cavity of the vacuum chamber 1. Figure 1 Four induction coils are omitted from the text.

[0055] Furthermore, a high-frequency power supply 5 is installed inside the cavity of vacuum chamber 1, and the high-frequency power supply 5 is located above the cavity of vacuum chamber 1.

[0056] Furthermore, four induction coils are disposed on the substrate 2 inside the vacuum chamber 1, such as... Figure 4 The diagram shows the target configuration of the sputtering system of the present invention. An induction coil is disposed between adjacent planar magnetron targets 3. Figure 4 In the diagram, ICP represents induction coils. Four induction coils and two central cylindrical magnetron targets 4 form an induced coupling electric field, which can excite high-density plasma-assisted deposition. The target center spacing between adjacent planar magnetron targets 3 is 800 mm.

[0057] The high-frequency power supply 5 uses a 13.56 MHz high-frequency source to excite the induction coil, and is paired with a matching network to ensure that the plasma uniformly fills the entire vacuum cavity and covers the area directly above the substrate 2 and the vacuum chamber entrance 11. The sputtering system has a structure that effectively improves the activation ratio of sputtered particles and ions, reduces the target shading effect, and improves the film density.

[0058] like Figure 3As shown, four 8-12 inch planar magnetron targets 3 are provided. The four planar magnetron targets 3 are arranged around the outer edge of the substrate 2. The four planar magnetron targets 3 are tilted inward at a γ angle of 20° to 45° to provide a wide-angle sputtering source.

[0059] like Figure 5 The diagram shown illustrates a simplified layout of the planar magnetron target 3, cylindrical magnetron target 4, and induction coil in the sputtering system of the present invention. P1, P2, P3, and P4 represent four planar magnetron targets 3, C1 represents the cylindrical magnetron target 4 at the center, and ICP represents the induction coil.

[0060] Two cylindrical magnetron targets 4 (C1) are arranged in a 6-inch vertical layout to directly perform plating on the central area of ​​the TGV.

[0061] The target-substrate distance (TSD) of the cylindrical magnetron target 4 is set to 90~150 mm. Here, the target-substrate distance (TSD) is the distance from the surface of the cylindrical magnetron target 4 to the surface of the substrate 2.

[0062] The rotation speed of substrate 2 is 20~30 RPM.

[0063] The sputtering system can be dynamically optimized through magnetic field scanning, substrate 2 rotation, and target-substrate distance (TSD) adjustment.

[0064] The air pressure inside vacuum chamber 1 is 2~30 mtorr.

[0065] The planar magnetron target 3 has a power of 4~6 W / cm², the cylindrical magnetron target 4 has a power of 6~10 KW / M, and the high-frequency power supply 5 has a power of 400~800 W, which can quickly complete the deposition of a complete seed layer on one side.

[0066] Figure 6 This is a single-sided film thickness distribution diagram inside the hole of the present invention (9:1 TGV hole, diameter 35 µm, depth 300 µm).

[0067] Figure 7 This is a single-sided film thickness distribution diagram inside the hole of the present invention (2:1 TGV hole, diameter 5 µm, depth 10 µm).

[0068] Figure 6 , Figure 7 The figure shows the single-sided film thickness distribution of the present invention in vias with different aspect ratios. It can be seen that, regardless of whether it is a high aspect ratio (9:1 TGV via, diameter 35 µm, depth 300 µm) or a medium aspect ratio (2:1 TGV via, diameter 5 µm, depth 10 µm), the film layer provides continuous coverage from the via opening to the via bottom, with no interruption on the sidewalls. The thickness at the via bottom is effectively compensated, proving that the present invention can achieve a stable step coverage rate under different structural conditions, which is beneficial to the conductivity reliability of subsequent electroplating or via filling processes.

[0069] Figure 8 , Figure 9 The image shown corresponds to Figure 6 , Figure 7 The film thickness distribution in the plane was observed. The results showed that the film thickness was uniformly distributed in the plane of the entire substrate 2 with small fluctuations. This indicates that by dynamically averaging the film thickness through the rotation of substrate 2 and the magnetic field / target scanning, the present invention can achieve low U% planar uniformity while ensuring through-hole coverage, making it suitable for large-area continuous production.

[0070] The sputtering system of the present invention was tested, and the experimental parameters were set as shown in Table 1. The target arrangement radius R was the distance between the center of the planar magnetron target 3 and the center of the set of cylindrical magnetron targets 4. The performance of the sputtering system of the present invention was tested and compared with the performance of a traditional sputtering system. The results are shown in Table 2.

[0071] Table 1

[0072]

[0073] Table 2

[0074]

[0075] The high-frequency power supply 5 is excited by a 13.56 MHz high-frequency source and matched with a matching network to make the plasma uniformly fill the entire cavity and cover the area directly above the substrate 2 and the entrance area of ​​the substrate 2.

[0076] The synergistic effect of a circumferentially tilted planar magnetron target 3, a central cylindrical magnetron target 4, and an induction coil is utilized to simultaneously improve the uniformity of planar film thickness and the coverage of deep holes. The induction coil is excited by a 13.56 MHz high-frequency power supply 5, and with the matching network, the plasma uniformly fills the entire vacuum cavity and covers the area directly above the substrate 2 and the entrance region of the substrate 2. An alternating magnetic field is generated in the vacuum cavity, which in turn induces a circumferential electric field in the plasma, inductively heating the free electrons. This results in an increase in plasma density and a more uniform distribution in the area above the substrate 2 and near the hole.

[0077] Under the above conditions (high-frequency power supply 5 + circumferentially tilted planar magnetron target 3 + central cylindrical magnetron target 4 + induction coil), on the one hand, stable discharge can be maintained under lower process pressure, which increases the mean free path of sputtered particles, reduces scattering, and enhances incident directionality; on the other hand, the increased plasma density near the substrate 2 causes some sputtered atoms to be ionized in front of the substrate 2, forming charged particles. These charged particles are incident near normal under the influence of the sheath potential of the substrate 2, effectively reducing the lateral shadowing effect and improving the film continuity between the bottom of the hole and the sidewall.

[0078] Meanwhile, the planar magnetron target 3 provides an oblique flux from the outside in, and the cylindrical magnetron target 4 provides an axial flux that can be dynamically averaged. The high-density plasma formed by the two and the induction coil is superimposed, and after the substrate 2 is rotated and the magnetic field / target is scanned, the particle flux is spatially averaged in the plane, thereby obtaining a low U% planar uniformity and a high step coverage. This mechanism also helps to improve the film density and deposition stability.

[0079] The above technical features constitute the preferred embodiment of the present invention, which has strong adaptability and optimal implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the needs of different situations.

[0080] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A sputtering system based on coil inductive coupling, comprising a vacuum chamber and a substrate disposed within the vacuum chamber, characterized in that, Four inclined, encircling planar magnetron targets are arranged on the substrate inside the vacuum chamber, and two cylindrical magnetron targets are arranged at the central axis of the vacuum chamber. Four induction coils are arranged inside the vacuum chamber to form an induced coupling electric field with the cylindrical magnetron targets. The inductively coupled electric field can excite high-density plasma-assisted deposition. An induction coil is placed between adjacent planar magnetron targets; It also includes a high-frequency power supply installed at the top of the vacuum chamber; Four planar magnetron targets are arranged around the outer edge of the substrate; Four planar magnetron targets are tilted inward at γ angles of 20° to 45°. The target-to-base distance (TSD) of the cylindrical magnetron target is set to 90~150mm; The planar magnetron target provides an oblique flux from the outside in, while the cylindrical magnetron target provides an axial flux that can be dynamically averaged. The two are superimposed on the high-density plasma formed by the induction coil.

2. The sputtering system based on coil inductive coupling assisted according to claim 1, characterized in that, The high-frequency power supply uses a 13.56MHz high-frequency source.

3. The sputtering system based on coil inductive coupling assisted according to claim 1, characterized in that, It is equipped with four 8-12 inch planar magnetron targets.

4. The sputtering system based on coil inductive coupling assisted according to claim 1, characterized in that, The cylindrical magnetron target adopts a 6-inch vertical layout.

5. A sputtering system based on coil inductive coupling assisted according to claim 1, characterized in that, The substrate rotation speed is 20~30 RPM.

6. The sputtering system based on coil inductive coupling assisted according to claim 1, characterized in that, The air pressure inside the vacuum chamber is 2~30 mtorr.

7. A sputtering system based on coil inductive coupling assisted according to claim 1, characterized in that, The power of the planar magnetron target is 4~6 W / cm², the power of the cylindrical magnetron target is 6~10 KW / M, and the power of the induction coil is 400~800 W.

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