A Glass Magnetron Sputtering Coating Method with Target Surface Magnetic Field Directional Enhancement and Confinement

Abstract

This invention discloses a glass magnetron sputtering coating method with target-surface magnetic field-oriented enhancement and confinement. The target-surface magnetic field is formed near the target surface of the target tube. The target surface within the working area is the first target surface, and the target surface outside the working area is the second target surface. The portion of the target-surface magnetic field corresponding to the first target surface is the working magnetic field, which penetrates the first target surface from the inside out, and the portion passing through the target surface is located within the working area, confining secondary electrons within the working area. The portion corresponding to the second target surface is the non-working magnetic field. When the particle sputtering rate on the first target surface is lower than the particle deposition rate, the working magnetic field is enhanced, and during this enhancement, the working magnetic field is confined within the working area, while the non-working magnetic field is confined inside the second target surface. This invention, by adjusting and confining the target-surface magnetic field, forms a fixed period where the sputtering rate is dominant at any point on the target surface during a single rotation cycle, and eliminates the period where the deposition rate is dominant, thereby suppressing target-surface nodule formation.

Description

Technical Field

[0001] This invention relates to the field of magnetron sputtering technology, and in particular to a glass magnetron sputtering coating method with target surface magnetic field orientation enhancement constraint. Background Technology

[0002] Magnetron sputtering is commonly used in vacuum glass coating, and target surface nodule formation is a key factor affecting the coating quality and process stability. Existing solutions are mostly reactive, such as removing the target tube for polishing during equipment maintenance, which is time-consuming, labor-intensive, and wasteful of target material. Furthermore, while rotating targets are often used to improve target utilization, their physical structure limits the effective etching area to a narrow arc. Moreover, based on existing negative magnetic field confinement methods, the target tube may still be affected by stray magnetic fields after rotating away from the effective etching area, leading to unexpected abnormal discharges and particle redeposition in the non-working area, further exacerbating the risk of nodule formation. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the prior art, the present invention provides a glass magnetron sputtering coating method with target surface magnetic field orientation enhancement constraint. By adjusting and constraining the target surface magnetic field, a fixed period in which the sputtering rate is dominant is formed at any point on the target tube surface during a single rotation cycle, and the period in which the deposition rate is dominant is eliminated, so as to suppress the target surface nodule phenomenon.

[0004] Technical solution: To achieve the above objectives, the present invention provides a glass magnetron sputtering coating method with target surface magnetic field orientation enhancement constraint, which is applied to a glass magnetron sputtering coating system. The coating system includes a target tube and a glass substrate located on one side of the target tube. The area between the glass substrate and the target tube is a working area. The target surface of the target tube located within the working area is a first target surface, and the target surface located outside the working area is a second target surface.

[0005] A target surface magnetic field is formed near the target surface of the target tube. The portion of the target surface magnetic field corresponding to the first target surface is the working magnetic field, and the portion corresponding to the second target surface is the non-working magnetic field. The working magnetic field penetrates the first target surface from the inside out, and the portion passing through the target surface is located within the working area, constraining secondary electrons within the working area. The constraining force of the working magnetic field on electrons is greater than that of the non-working magnetic field. When the particle sputtering rate on the first target surface is lower than the particle deposition rate, the target surface magnetic field increases its magnetic field strength. The magnetic field strengths of the working magnetic field and the non-working magnetic field are adjusted synchronously. When the magnetic field strength of the working magnetic field increases, the working magnetic field is constrained within the working area, and the non-working magnetic field is constrained inside the second target surface.

[0006] Furthermore, an active magnetic field is generated inside the target tube, and the local magnetic field lines of the source magnetic field penetrate the first target surface to form the target surface magnetic field.

[0007] Furthermore, the source magnetic field is an asymmetric magnetic field, with the magnetic field strength on the side closer to the working area being higher than that on the side away from the working area.

[0008] Furthermore, the magnetic circuit excitation substrate of the source magnetic field is located close to the working area.

[0009] Furthermore, along the length of the target tube, the distance between the magnetic circuit excitation substrate and the first target surface is matched with the sputtering consumption rate of the first target surface.

[0010] Furthermore, during the enhancement of the working magnetic field, the magnetic field lines of the source magnetic field near the working area converge into the narrow working area.

[0011] Furthermore, after the working magnetic field is enhanced, its magnetic field energy is concentrated in the effective sputtering area, which is located within the working area and in the direction of the target surface normal.

[0012] Furthermore, during operation, the working magnetic field as a whole reciprocates to scan the first target surface along the length of the target tube.

[0013] Furthermore, during the enhancement of the working magnetic field, the path of the source magnetic field diffusing outward at both ends of the target tube is cut off, and the leakage magnetic field escaping from the second target surface is absorbed.

[0014] Furthermore, during the enhancement process of the working magnetic field, a dynamic scanning enhancement is formed in the axial direction of the target tube or in the circumferential direction of the first target surface.

[0015] Beneficial Effects: This invention provides a glass magnetron sputtering coating method with targeted magnetic field enhancement and controllable constraint. By directionally enhancing and controlling the magnetic field on the target surface, it achieves precise constraint on the effective sputtering area of ​​the target surface while maintaining high utilization of the rotating target material. This ensures that regardless of the magnetic field enhancement, the effective sputtering area remains within the working area, while simultaneously suppressing stray magnetic field interference in non-working areas, thus preventing target surface nodule formation at its source. This comprehensively improves both target material utilization and glass coating quality. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the target magnetic field directional enhancement constraint method for inhibiting nodule formation according to the present invention. Detailed Implementation

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] As attached Figure 1The aforementioned target-surface magnetic field-oriented enhanced confinement glass magnetron sputtering coating method is applied to a glass magnetron sputtering coating system. The coating system includes a target tube 1 and a glass substrate 2 located on one side of the target tube 1. Both the target tube 1 and the glass substrate 2 are located in a vacuum working gas environment and a working electric field to realize the basic magnetron sputtering coating function.

[0019] The target surface magnetic field is formed near the target surface to confine more secondary electrons in the vicinity of the target surface, thereby improving the ionization efficiency of argon gas near the target surface. + The density is used to maintain the continuous sputtering process and ensure the successful completion of the coating.

[0020] In practical applications of glass vacuum coating, rotating targets are often used to overcome the defects of low utilization and uneven etching of planar targets. These rotating targets utilize their circumferential surfaces to alternately enter the effective sputtering area, achieving high-efficiency target utilization. However, due to the cylindrical geometry of the target tube, the effective sputtering area between it and the flat glass substrate is significantly narrower than that of a planar target. At any given time, only the tangential region of the target surface closest to the glass substrate is in an effective sputtering coating state, while the remaining circumferential surfaces deviate from the direct sputtering direction. Furthermore, since the particles sputtered from the rotating target follow a cosine distribution law, if a uniform magnetic field is formed near the entire target surface, a large number of particles will fly towards the cavity walls and other non-glass substrate areas of the vacuum chamber, reducing the effective deposition rate of the material.

[0021] In this embodiment, the effective face-to-face sputtering region between the glass substrate 2 and the target tube 1 is defined as the working region 3; the target surface of the target tube 1 located within the working region is the first target surface 11, and the target surface located outside the working region is the second target surface 12. By constraining the target surface magnetic field, effective sputtering is performed only on the first target surface 11, ensuring that all particles sputtered from the first target surface 11 can effectively act on the surface of the glass substrate. At the same time, abnormal discharge near the second target surface 12 is suppressed.

[0022] The principle is that when the target tube surface leaves the working area 3, if a magnetic field still exists, the particle redeposition rate on the target surface will continue to be higher than the sputtering removal rate. Since the working area 3 is narrow, the target tube surface is outside of it most of the time. Redeposited particles repeatedly accumulate on the target tube surface. If they are not completely removed by sputtering when passing through the working area 3, they will sinter into nodules after repeated rotational heating, easily causing nodule formation on the target tube surface. Therefore, by directionally enhancing the magnetic field near the first target surface 11 and suppressing diffusion near the second target surface 12, efficient sputtering deposition can be achieved within the working area 3 while simultaneously achieving self-cleaning, reducing the risk of particles re-depositing back onto the target tube surface outside the working area 3.

[0023] Since the narrow width d of the working area 3 described in this scheme is an inherent defect caused by the structure, this scheme considers defining the effective range of the target surface magnetic field as the working magnetic field and confining it within the narrow working area 3, while defining the other magnetic field parts as the non-working magnetic field and confining them inside the second target surface 12.

[0024] Typically, the target surface magnetic field is generated by a magnetron located inside the target tube. The magnetron is usually formed by arranging magnet components or direct-current electromagnets. Theoretically, the magnetic field can extend to infinity. Therefore, magnetic field lines will inevitably pass through the second target surface 12, causing the aforementioned defects and resulting in nodules on the target tube surface.

[0025] In actual production, it was found that increasing the magnetic field strength generated by the magnetron can enhance the confinement force on secondary electrons on the target surface, thereby increasing the plasma density. By increasing the sputtering rate, redeposited particles can be re-sputtered before nodulation, thus suppressing the nodulation rate. However, since the working and non-working magnetic fields are generated by the same magnetron and are enhanced synchronously, the sputtering rate of the first target surface 11 increases while the deposition rate of the second target surface 12 also increases, resulting in limited effectiveness in suppressing nodulation.

[0026] Therefore, this scheme considers constructing an asymmetric spatial magnetic field distribution to achieve a strong confinement effect on secondary electrons only near the target surface within the working region 3, thereby improving the ionization efficiency within the working region 3 and increasing the plasma density within the working region 3. This enhances the sputtering rate of the first target surface 11. High-frequency sputtering also increases the flux of sputtered target particles, allowing particles that were initially prone to redeposition due to insufficient power or orbital deviation to regain power and flow towards the glass substrate under the impetus of a high-density directional particle flow pointing towards the glass substrate. This reduces the particle deposition rate on the first target surface 11, thus helping to ensure that the particle sputtering rate within the working region 3 is higher than the particle deposition rate. In other areas outside the working region 3, the ionization of argon gas is suppressed as much as possible.

[0027] Specifically, the magnetic field generated by the magnetron is defined as the source magnetic field. First, the magnetron or the magnet assembly within the magnetron is positioned close to the glass substrate inside the target tube 1. This ensures that only the effective magnetic field lines near the working area 3 pass through the first target surface 11 to form the working magnetic field. Within a certain range of magnetic field strength adjustment, the effective magnetic field lines away from the working area 3 are insufficient to pass through the second target surface 12, forming a magnetic field with side effects. However, this method still has limitations. When the magnetic field strength needs to be further increased, the source magnetic field will still pass through the second target surface 12, causing interference.

[0028] Therefore, it is further considered to design the magnetic circuit of the source magnetic field asymmetrically, so that the magnetic field strength on the side closer to the working area 3 is higher than that on the side away from the working area 3. Optionally, a magnetic assembly can be formed by arranging permanent magnets with specific magnetization directions, so that the magnetic field lines are superimposed and enhanced on the side closer to the working area 3, while canceling each other out and attenuating on the side away from the working area 3; or a single permanent magnet or electromagnet with a specific cross-sectional structure can be used directly, such as a mountain-shaped cross-section, in which the middle peak is the S pole and the two symmetrical peaks on both sides are N poles, so that most of the magnetic field lines are concentrated on the open side, and in actual installation, the open side can be set to face the working area 3.

[0029] Based on the above structure, although most of the magnetic field lines are concentrated on one side of the working area 3, as the magnetic field strength continuously increases, the effective range of the working magnetic field may expand beyond the working area 3. Therefore, during the process of increasing the working magnetic field strength, it is necessary to gather the magnetic field lines of the source magnetic field near the working area 3 into the narrow working area 3. For example, irregularly shaped magnetic conductive structures can be added to both sides of the magnet that generates the source magnetic field. By changing the magnetic resistance of the magnetic circuit, the magnetic field lines can be squeezed and gathered into the working area 3. This ensures that when the magnetic field strength of the working magnetic field increases, the working magnetic field remains confined within the working area 3.

[0030] Based on the asymmetric magnetic field design and the eccentric setting of the magnet, the enhancement range of the working magnetic field has been significantly improved without the influence of non-working magnetic field leakage. However, there is still a risk of non-working magnetic field leakage when further enhancing the field. Therefore, the path of the source magnetic field spreading outward at both ends of the target tube 1 is further cut off. For example, by adding a short-circuit structure made of high-permeability material to the non-working areas at both ends of the target tube, this structure can directly guide the magnetic lines of force leaking to the ends of the target tube back into the magnetic circuit, thereby cutting off the path of stray field spreading outward at both ends and avoiding the nodulation problem induced by abnormal discharge in the non-working areas at both ends.

[0031] Simultaneously, the leakage magnetic field escaping from the source magnetic field out of the second target surface 12 is absorbed or shielded to prevent it from leaking through the second target surface 12, thus ensuring that even when the magnetic field strength of the working magnetic field increases, the non-working magnetic field remains confined inside the second target surface 12. For example, a shielding shell structure made of a high-permeability material is fixedly installed on the side of the magnet away from the working area 3.

[0032] Based on the above constraints, the source magnetic field's magnetic field lines penetrate only partially through the first target surface 11 to form the target surface magnetic field. This ensures that after the working magnetic field is enhanced, its magnetic field energy is concentrated in the effective sputtering region 31, which is located within the working area 3 and along the normal direction of the target surface.

[0033] Preferably, the distance between the magnetic circuit excitation substrate and the first target surface 11 along the length of the target tube is matched with the sputtering consumption rate of the first target surface 11. For example, the spacing between regions with faster consumption is adjusted to be larger, and the spacing between regions with slower consumption is adjusted to be smaller, thereby eliminating the phenomenon of uneven etching of the first target surface 11 along its entire length and delaying the formation of nodules caused by uneven etching.

[0034] Preferably, during operation, the working magnetic field reciprocates along the length of the target tube 1, scanning the first target surface 11. For example, it drives the entire magnetron to move back and forth or oscillate slightly along the axis of the target tube. Based on the uniform etching rate along the overall length, this further improves the uniformity of the etching groove depth along the length, preventing local protrusions from becoming nodule growth points and inhibiting the formation of nodules from the root. At the same time, the concentration of magnetic field energy in the effective sputtering area 31 helps to make the etching groove narrower and deeper, making it less likely for redeposited particles to fall into the groove and form nodules.

[0035] Preferably, during the enhancement of the working magnetic field, a dynamic scanning enhancement is formed along the axial direction of the target tube 1 or around the first target surface 11. For example, multiple independent electromagnets are used, and the dynamic scanning enhancement is achieved by adjusting the timing of switching on and off or adjusting the current magnitude, so as to avoid local target material depletion and nodule formation caused by the fixed position of the effective sputtering area 31 and excessive etching.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the above principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A glass magnetron sputtering coating method with target surface magnetic field orientation enhancement confinement, applied to a glass magnetron sputtering coating system, the coating system including a target tube (1) and a glass substrate (2) located on one side of the target tube (1), the glass substrate (2) and the target tube (1) being a working area (3); the target surface of the target tube (1) located within the working area is a first target surface (11), and the target surface located outside the working area is a second target surface (12). Its features are: A target surface magnetic field is formed near the target surface of the target tube (1). The part of the target surface magnetic field corresponding to the first target surface (11) is the working magnetic field, and the part corresponding to the second target surface (12) is the non-working magnetic field. The working magnetic field penetrates the first target surface (11) from the inside out, and the part that passes through the target surface is located in the working area (3), and constrains the secondary electrons in the working area; the constraining force of the working magnetic field on the electrons is greater than the constraining force of the non-working magnetic field on the electrons. When the particle sputtering rate on the first target surface (11) is lower than the particle deposition rate, the target surface magnetic field enhances the magnetic field strength; wherein, the magnetic field strength of the working magnetic field and the non-working magnetic field are adjusted synchronously. When the magnetic field strength of the working magnetic field increases, the working magnetic field is confined within the working area (3), and the non-working magnetic field is confined inside the second target surface (12).

2. The glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 1, characterized in that: An active magnetic field is generated inside the target tube (1), and the local magnetic field lines of the source magnetic field penetrate the first target surface (11) to form the target surface magnetic field.

3. The glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 2, characterized in that: The source magnetic field is an asymmetric magnetic field, with the magnetic field strength on the side closer to the working area (3) being higher than that on the side away from the working area (3).

4. A glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 2 or 3, characterized in that: The magnetic circuit excitation substrate of the source magnetic field is close to the working region (3).

5. The glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 4, characterized in that: The distance between the magnetic circuit excitation substrate and the first target surface (11) along the length of the target tube is matched with the sputtering consumption rate of the first target surface (11).

6. The glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 2, characterized in that: During the enhancement of the working magnetic field, the magnetic field lines of the source magnetic field near the working area (3) converge into the narrow working area (3).

7. The glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 6, characterized in that: After the working magnetic field is enhanced, its magnetic field energy is concentrated in the effective sputtering area (31), which is located in the working area (3) and in the direction of the target surface normal.

8. The glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 7, characterized in that: During operation, the working magnetic field as a whole scans the first target surface (11) along the length of the target tube (1).

9. The glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 6, characterized in that: During the enhancement of the working magnetic field, the path of the source magnetic field to diffuse outward at both ends of the target tube (1) is cut off, and the leakage magnetic field of the source magnetic field escaping from the second target surface (12) is absorbed.

10. The glass magnetron sputtering coating method with target surface magnetic field orientation enhancement and confinement according to claim 1, characterized in that: During the enhancement process of the working magnetic field, a dynamic scanning enhancement is formed in the axial direction of the target tube (1) or in the circumferential direction of the first target surface (11).

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