Plasma cleaning device and cleaning system for metal strips

Abstract

The present invention provides a plasma cleaning device and a cleaning system for a metal strip, and relates to the technical field of chip manufacturing. The cleaning device comprises a frame, an insulating spacer and a plasma excitation structure. The plasma excitation structure comprises a high-frequency electrode and a ground electrode. The frame is provided with a chamber and an air inlet, and the high-frequency electrode and the ground electrode are fixed to the frame through an insulating spacer, and the spacing between the high-frequency electrode and the ground electrode is uniform. The high-frequency electrode is provided with a first air hole, and the ground electrode is evenly distributed with a second air hole, and a plurality of second air holes are used for uniform gas outlet. The cleaning system comprises a high-frequency controller, an air source and a cleaning device. The cleaning device and the cleaning system are provided with high-frequency electrodes and ground electrodes with equal spacing, and further designed with first air holes and second air holes for uniform gas outlet, so that the metal strip can be cleaned by uniform plasma gas, and the cleaning effect is not different due to different thicknesses, which is of great significance to the field of semiconductor bonding.

Description

Technical Field

[0001] The present invention relates to the technical field of chip manufacturing, and in particular to a plasma cleaning device and a cleaning system for a metal strip. Background Art

[0002] The chip and the lead frame need to be connected by bonding wires. With the development of power semiconductors, facing the application of high power and high current, bonding wires are increasingly unable to meet the application of high current. Therefore, the use of metal strips to connect the chip to the lead frame or substrate is becoming more and more common. Compared with wires, strips have greater current carrying capacity and a larger connection area, which effectively reduces impedance and is of great significance for power semiconductors.

[0003] The surface cleanliness of the bonding strip is closely related to the bonding quality, so the surface contaminants need to be removed during manufacturing; contaminants also need to be removed during bonding to avoid the adverse effects caused by the thickening of the oxide film during long-term storage. Compared with chemical cleaning, plasma cleaning, as an environmentally friendly and efficient cleaning method, is more in line with the needs of bonding materials.

[0004] Some existing plasma cleaning devices can clean some wires, but due to the changes in strip materials and thickness, the distance between the high-frequency electrode and the lead in the generating chamber will change. This change will cause the plasma to fluctuate, resulting in inconsistent cleaning effects. Summary of the invention

[0005] The object of the present invention is to provide a plasma cleaning device for metal strips, which can improve the problem that the existing plasma cleaning devices cannot meet the cleaning requirements of the strips.

[0006] Another object of the present invention is to provide a cleaning system, which includes the above-mentioned plasma cleaning device for metal strips and has all the characteristics of the plasma cleaning device for metal strips.

[0007] An embodiment of the present invention is implemented as follows: An embodiment of the present invention provides a plasma cleaning device for metal strips, comprising: a frame, an insulating spacer and a plasma excitation structure; the plasma excitation structure comprises a high-frequency electrode and a grounding electrode, the high-frequency electrode and the grounding electrode are used to connect a high-frequency controller; the frame is provided with a chamber and an air inlet, the chamber can be connected to an external gas source through the air inlet, the high-frequency electrode and the grounding electrode are fixed to the frame through the insulating spacer, and the spacing between the high-frequency electrode and the grounding electrode is uniform; the high-frequency electrode is provided with a first air hole, the grounding electrode is evenly distributed with a plurality of second air holes, the air inlet is connected with the chamber, the first air hole, and the second air hole in sequence to form a gas channel, and the plurality of second air holes are used for uniform gas outlet.

[0008] In addition, the plasma cleaning device for metal strips provided according to the embodiment of the present invention may also have the following additional technical features: in an optional embodiment of the present invention, the insulating spacer is made of plastic, ceramic or glass.

[0009] In an optional embodiment of the present invention, the plasma cleaning device for the metal strip includes a gas source, and the gas inlet is connected to the gas source; the gas of the gas source is nitrogen, argon, helium, hydrogen, CF4 or SF6; or, the gas of the gas source is a mixture of any two of nitrogen, argon, helium, hydrogen, CF4, SF6; or, the gas of the gas source is a mixture of any three of nitrogen, argon, helium, hydrogen, CF4, SF6.

[0010] In an optional embodiment of the present invention, the distance between the high-frequency electrode and the ground electrode is 0.1 mm-5 mm.

[0011] In an optional embodiment of the present invention, there is a distance between the ground electrode and the metal strip to be cleaned, and the distance between the ground electrode and the metal strip to be cleaned is 1-20 mm.

[0012] In an optional embodiment of the present invention, the high-frequency electrode and the grounding electrode are both flat-plate electrodes; or, the high-frequency electrode and the grounding electrode are both annular electrodes.

[0013] An embodiment of the present invention provides a cleaning system, comprising a high-frequency controller, a gas source and a plasma cleaning device for a metal strip as described in any one of the above items, wherein the high-frequency controller is electrically connected to the high-frequency electrode and the ground electrode, and the gas source is connected to the air inlet of the frame and can supply gas to the chamber.

[0014] In an optional embodiment of the present invention, the number of the plasma cleaning devices for the metal strip is two, and the two plasma cleaning devices for the metal strip are arranged on both sides of the metal strip to be cleaned.

[0015] In an optional embodiment of the present invention, when the high-frequency electrode and the grounding electrode are in an annular shape, the middle area of ​​the annular grounding electrode is a cleaning space, and the cleaning space is used to accommodate the metal strip to be cleaned.

[0016] In an optional embodiment of the present invention, the cleaning system further comprises a conveying device, and the conveying device is used to drive the metal strip to pass through the gas outlet area of ​​the second gas hole of the ground electrode.

[0017] The beneficial effects of the present invention are as follows: the plasma cleaning device for metal strips sets high-frequency electrodes and ground electrodes with equal spacing so that the plasma between the two is uniform, and further designs the first air hole and the second air hole for uniform gas outlet so that the metal strip can be cleaned by uniform plasma gas, and the cleaning effect is not different due to different thicknesses. It has good versatility and is of great significance to the field of semiconductor bonding. By cooperating with a high-frequency controller and a gas source to form a cleaning system, it can continuously perform plasma cleaning on strips of different thicknesses, and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic structural diagram of a plasma cleaning device for metal strips provided in Example 1 of the present invention;

[0020] Figure 2 It is a schematic diagram of the coordination between the high-frequency electrode, the grounding electrode, the high-frequency controller and the metal strip;

[0021] Figure 3 is a schematic diagram of a cleaning system;

[0022] Figure 4 A schematic diagram of another cleaning system.

[0023] Icon: 1000 - plasma cleaning device for metal strip; 1 - frame; 101 - chamber; 2 - insulating spacer; 3 - high-frequency electrode; 4 - grounding electrode; 5 - plasma gas; 6 - metal strip; 7 - first air hole; 8 - high-frequency controller; 9 - transmission roller; 11 - air inlet; 12 - second air hole; 13 - cleaning space. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0027] In the description of the present invention, it should be noted that the terms "upper", "lower", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the present invention, unless otherwise clearly specified and limited, a first feature being above or below a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, a first feature being above, above, and above a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being below, below, and below a second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature. Example

[0030] Please refer to Figure 1 and Figure 2The embodiment of the present invention provides a plasma cleaning device 1000 for metal strips, comprising: a frame 1, an insulating spacer 2 and a plasma excitation structure; the plasma excitation structure comprises a high-frequency electrode 3 and a grounding electrode 4, and the high-frequency electrode 3 and the grounding electrode 4 are used to connect a high-frequency controller 8; the frame 1 has a chamber 101 and an air inlet 11, the chamber 101 can be connected to an external gas source through the air inlet 11, the high-frequency electrode 3 and the grounding electrode 4 are fixed to the frame 1 through the insulating spacer 2, and the spacing between the high-frequency electrode 3 and the grounding electrode 4 is uniform; the high-frequency electrode 3 is provided with a first air hole 7, and the grounding electrode 4 is uniformly distributed with a plurality of second air holes 12, the air inlet 11 is sequentially connected with the chamber 101, the first air hole 7, and the second air hole 12 to form a gas channel, and the plurality of second air holes 12 are used for uniform gas discharge.

[0031] Please combine Figure 1 In this embodiment, the insulating spacer 2 is fixed on two opposite sides of the frame 1. Figure 1 In the viewing direction, the high-frequency electrode 3 is embedded in the insulating spacer 2, the space above the high-frequency electrode 3 is the above-mentioned chamber 101, and the grounding electrode 4 is embedded in the insulating spacer 2 and is located below the high-frequency electrode 3, with a distance between them. The arrow in the figure shows the direction of gas flow.

[0032] The high-frequency electrode 3 and the ground electrode 4 are made of metal or non-metal conductive materials such as copper, aluminum, steel, and graphite.

[0033] It can be understood that the plasma cleaning device 1000 for metal strip in the present embodiment is used to perform plasma cleaning on the metal strip 6. When the strip is of other types, the plasma cleaning device 1000 for metal strip in the present embodiment can also be considered to perform plasma cleaning. The present application is not limited to cleaning only the metal strip 6, nor should it be restrictively understood that using the plasma cleaning device 1000 for metal strip of the present application to clean other strips does not fall within the scope of use or protection scope of the present application.

[0034] Specifically, in this embodiment, the distance between the high-frequency electrode 3 and the ground electrode 4 is 0.1 mm-5 mm. The ground electrode 4 and the metal strip 6 to be cleaned have a distance, and the distance between the ground electrode 4 and the metal strip 6 to be cleaned is 1-20 mm.

[0035] It should be noted that the above-mentioned spacing between the high-frequency electrode 3 and the grounding electrode 4, and the spacing between the grounding electrode 4 and the metal strip 6 to be cleaned are examples of this embodiment. People skilled in the art can also select other spacing parameters based on this, as long as the final parameter selection can meet the cleaning requirements of the metal strip 6.

[0036] In addition, the above-mentioned spacing parameter selection between the high-frequency electrode 3 and the ground electrode 4 refers to a fixed value, for example, the spacing between the high-frequency electrode 3 and the ground electrode 4 is 0.1 mm everywhere, 1 mm everywhere, or 5 mm everywhere, etc. After a fixed parameter is selected, the spacing between the two is always the parameter, rather than the spacing between the two having multiple changes at the same time.

[0037] The spacing between the ground electrode 4 and the metal strip 6 to be cleaned is selected within the spacing range, and the metal strip 6 can obtain a good cleaning effect. This is because, for semiconductor products of different powers, some may use a 0.2mm thick strip, and some may use a 0.05mm thick strip. However, no matter what the thickness of the strip is, after being placed in the gas outlet range of the ground electrode 4, the distance from the ground electrode 4 generally meets the above requirements, and usually can ensure a good cleaning effect. In this way, even if the thickness of the metal strip 6 changes, it will not cause the plasma gas 5 coming out of the second air hole 12 to fluctuate, so as to avoid affecting the cleaning effect.

[0038] Please combine Figure 2 , it can be selected that the high-frequency electrode 3 and the ground electrode 4 are both flat-plate electrodes; Figure 4 Alternatively, the high-frequency electrode 3 and the ground electrode 4 are both annular electrodes.

[0039] When in use, if only one side of the strip needs to be cleaned, a single metal strip plasma cleaning device 1000 can be used, and if both sides of the strip need to be cleaned, two metal strip plasma cleaning devices 1000 can be used and arranged on the upper and lower sides of the strip. Of course, after cleaning one side of the strip, the other side of the strip can also be plasma cleaned.

[0040] Regardless of whether it is a flat electrode or a circular electrode, the distance between the high-frequency electrode 3 and the ground electrode 4 needs to be kept consistent everywhere to ensure that the generated plasma is uniform and ultimately ensure the cleaning effect for strips of different thicknesses.

[0041] Specifically, in this embodiment, there are multiple first air holes 7, and each first air hole 7 corresponds to the position of a second air hole 12. In this way, when external air enters the chamber 101 from the air inlet 11, it can enter the gap between the high-frequency electrode 3 and the ground electrode 4 from the multiple first air holes 7, and generate plasma gas 5, and then evenly penetrate from the multiple second air holes 12. Since the spacing between the high-frequency electrode 3 and the ground electrode 4 is consistent, the plasma is generated uniformly, and then sent out through the multiple uniformly distributed second air holes 12, so that the finally ejected plasma gas 5 can be uniform everywhere. When the plasma gas 5 flows to the metal strip 6, the surface of the metal strip 6 can be cleaned.

[0042] Among them, it is optional to set a swirl blade and an air distribution plate in the chamber 101. The swirl blade can disperse the gas entering the air inlet 11, and the dispersed gas can flow evenly after passing through the air holes evenly distributed on the air distribution plate. This allows the gas to flow more evenly to the first air holes 7 of the high-frequency electrode 3 after passing through the air distribution plate, and further to the second air holes 12.

[0043] Alternatively, the above-mentioned swirl blades and gas distribution plates may be arranged between the high-frequency electrode 3 and the ground electrode 4, so that the plasma gas 5 evenly reaches each second air hole 12 of the ground electrode 4. In this case, the number of the first air hole 7 may also be one, as long as it can ensure that the plasma gas 5 can be evenly delivered from the plurality of second air holes 12.

[0044] Alternatively, the positions of each first air hole 7 and the second air hole 12 may not be directly opposite or may not be completely opposite. After the gas enters from the air inlet 11, it can gradually diffuse to the first air hole 7 and diffuse between the high-frequency electrode 3 and the ground electrode 4, and then after contacting the ground electrode 4, it can reversely touch the high-frequency electrode 3 and finally fill the high-frequency electrode 3 and the ground electrode 4. The filled plasma gas 5 overflows from the second air hole 12 under the continuous supply. After ventilation for a period of time, the plasma gas 5 coming out of each second air hole 12 is uniform and can be used to clean the metal strip 6.

[0045] In this embodiment, the plasma cleaning device 1000 for metal strips includes a gas source, and the gas inlet 11 is connected to the gas source. The plasma cleaning device 1000 for metal strips can select a suitable gas source according to the condition of the metal strip 6 to be cleaned to obtain the desired cleaning effect.

[0046] It can be selected that the gas source of this embodiment is nitrogen, argon, helium, hydrogen, CF4 or SF6; or, the gas source gas is a mixture of any two of nitrogen, argon, helium, hydrogen, CF4, SF6; or, the gas source gas is a mixture of any three of nitrogen, argon, helium, hydrogen, CF4, SF6.

[0047] Optionally, in addition to the above-mentioned gas sources, other selections and mixtures may be made according to actual conditions to test out the desired gas source type.

[0048] As for the insulating spacer 2, in this embodiment, it is made of plastic, ceramic or glass. Of course, in addition to these materials, other insulating materials that can play an insulating role can also be used to make the insulating spacer 2 of this embodiment.

[0049] Please combine Figure 3 and Figure 4Based on the plasma cleaning device 1000 for metal strip, an embodiment of the present invention provides a cleaning system, including a high-frequency controller 8, a gas source and the above-mentioned plasma cleaning device 1000 for metal strip, the high-frequency controller 8 is electrically connected to the high-frequency electrode 3 and the ground electrode 4, the gas source is connected to the air inlet 11 of the frame 1 and can supply gas to the chamber 101.

[0050] The output frequency of the high frequency controller 8 of this embodiment is 1 MHz-100 MHz.

[0051] It should be noted that the present application does not show the gas source, which can supply gas to the chamber 101 through the gas inlet 11. Figure 4 The main figure shows the shape of the high-frequency electrode 3 and the grounding electrode 4 when they are in an annular shape, and other structures such as the frame 1 and the insulating spacer 2 are not shown. The frame 1 and the insulating spacer 2 only need to ensure that the high-frequency electrode 3 and the grounding electrode 4 are normally installed and work normally and can keep the spacing between them the same everywhere. Among them, the middle area of ​​the annular grounding electrode 4 is a cleaning space 13 for accommodating the metal strip 6 to be cleaned.

[0052] Please combine Figure 3 The number of the metal strip plasma cleaning devices 1000 used in the cleaning system in this embodiment is two, and the two metal strip plasma cleaning devices 1000 are arranged on both sides of the metal strip 6 to be cleaned.

[0053] The cleaning system further comprises a conveying device, which is used to drive the metal strip 6 to pass through the gas outlet area of ​​the second gas hole 12 of the ground electrode 4. The conveying device used in this embodiment is a transmission roller 9.

[0054] Whether Figure 3 still Figure 4 The cleaning system can continuously clean the metal strip 6. Since the plasma cleaning device 1000 for metal strip is adopted, the plasma between the high-frequency electrode 3 and the ground electrode 4 is uniform. When the plasma gas 5 is ejected through the second air holes 12, the plasma gas 5 of each second air hole 12 is uniformly sprayed onto the metal strip 6. Even if the thickness of the metal strip 6 is different, there is no need to worry about the fluctuation of the generated plasma due to the change in the distance between the high-frequency electrode 3.

[0055] In addition, according to the cleaning requirements, one metal strip plasma cleaning device 1000 may be turned on separately or two metal strip plasma cleaning devices 1000 may be turned on simultaneously to perform plasma cleaning on both surfaces of the metal strip 6 as required.

[0056] In summary, the plasma cleaning device 1000 of the metal strip of the present application sets the high-frequency electrode 3 and the ground electrode 4 with equal spacing, so that the plasma between the two is uniform, and further designs the first air hole 7 and the second air hole 12 for uniform gas outlet, so that the metal strip 6 can be cleaned by the uniform plasma gas 5, and the cleaning effect is not different due to different thicknesses. It has good versatility and is of great significance to the field of semiconductor bonding. By cooperating with the high-frequency controller 8 and the gas source to form a cleaning system, it is possible to continuously perform plasma cleaning on strips of different thicknesses, and has good practicality.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A plasma cleaning device for metal strips, characterized in that: include: A frame, an insulating spacer and a plasma excitation structure; the plasma excitation structure includes a high-frequency electrode and a ground electrode, the high-frequency electrode and the ground electrode are used to connect to a high-frequency controller; the frame has a chamber and an air inlet, the chamber can be connected to an external air source through the air inlet, the high-frequency electrode and the ground electrode are fixed to the frame through the insulating spacer, and the spacing between the high-frequency electrode and the ground electrode is uniform; The high-frequency electrode is provided with a first air hole, the ground electrode is evenly distributed with a plurality of second air holes, the air inlet is connected with the chamber, the first air hole, and the second air hole in sequence to form a gas channel, and the plurality of second air holes are used for uniform gas discharge.

2. The plasma cleaning device for metal strip according to claim 1, characterized in that: The insulating spacer is made of plastic, ceramic or glass.

3. The plasma cleaning device for metal strip according to claim 1, characterized in that: The plasma cleaning device for the metal strip includes a gas source, and the gas inlet is connected to the gas source; the gas of the gas source is nitrogen, argon, helium, hydrogen, CF4 or SF6; or, the gas of the gas source is a mixed gas of any two of nitrogen, argon, helium, hydrogen, CF4, and SF6; or, the gas of the gas source is a mixed gas of any three of nitrogen, argon, helium, hydrogen, CF4, and SF6.

4. The plasma cleaning device for metal strip according to claim 1, characterized in that: The distance between the high-frequency electrode and the ground electrode is 0.1 mm-5 mm.

5. The plasma cleaning device for metal strip according to claim 1, characterized in that: The ground electrode has a distance from the metal strip to be cleaned, and the distance between the ground electrode and the metal strip to be cleaned is 1-20 mm.

6. The plasma cleaning device for metal strip according to claim 1, characterized in that: The high-frequency electrode and the grounding electrode are both flat-plate electrodes; Alternatively, the high-frequency electrode and the ground electrode are both annular electrodes.

7. A cleaning system, characterized in that: A plasma cleaning device for metal strips comprising a high-frequency controller, a gas source and any one of claims 1 to 6, wherein the high-frequency controller is electrically connected to the high-frequency electrode and the ground electrode, and the gas source is connected to the gas inlet of the frame and can supply gas to the chamber.

8. The cleaning system according to claim 7, characterized in that: The number of the plasma cleaning devices for metal strips is two, and the two plasma cleaning devices for metal strips are arranged on both sides of the metal strip to be cleaned.

9. The cleaning system according to claim 8, characterized in that: When the high-frequency electrode and the grounding electrode are in an annular shape, the middle area of ​​the annular grounding electrode is a cleaning space, and the cleaning space is used to accommodate the metal strip to be cleaned.

10. The cleaning system according to claim 7, characterized in that: The cleaning system further comprises a conveying device, which is used to drive the metal strip to pass through the gas outlet area of ​​the second gas hole of the ground electrode.

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