Polishing head cleaning method and polishing head cleaning device

Abstract

A polishing head cleaning method, comprising the following steps: forming a conductive wafer bearing surface (2) on a polishing head (1), charged particle contaminants being attached to the wafer bearing surface (2); applying a voltage to the wafer bearing surface (2) of the polishing head; and delivering an electrolyte fluid (5) to the wafer bearing surface (2), the electrolyte fluid (5) flowing to drive the charged particle contaminants to be separated from the wafer bearing surface (2), so as to achieve cleaning of the polishing head. Also disclosed is a polishing head cleaning device. The voltage is applied to the polishing head to prompt the charged particle contaminants to be separated from the wafer bearing surface of the polishing head, in addition, the flowing electrolyte fluid continuously flushes the wafer bearing surface, such that the cleaning effect is better.

Description

Polishing head cleaning method and cleaning device Technical Field

[0001] The present invention belongs to the technical field of semiconductor integrated circuit chip manufacturing, and in particular relates to a polishing head cleaning method and a cleaning device. Background Art

[0002] Chemical mechanical polishing (CMP) is a key technology in integrated circuit manufacturing, widely used in front-end and back-end processes including transistor fabrication, metal wiring, and interconnect fabrication. The materials being polished range from Si, Cu, W, SiO2, and Si3N4, which are widely used in the integrated circuit field, to rapidly developing third-generation semiconductors such as SiC and GaN.

[0003] With the increasing variety of polishing materials, especially for polishing objects with good chemical stability and high hardness, it is necessary to add high-hardness abrasives to the polishing liquid, and even strong oxidants, and increase the polishing time. In these polishing conditions, the abrasives and additives in the polishing liquid can adhere to the polishing head due to electrostatic adsorption, which can easily cause abrasive accumulation on the polishing head. This is especially true for anionic and cationic surfactants (such as CTAB, SDS) and polymers with long carbon chains (such as PAA, PMMA). Traditional polishing head cleaning, mainly using deionized water (DIW), is difficult to completely remove the accumulated abrasives and other polishing liquid additives on the polishing head. Inadequate polishing head cleaning can leave abrasives on the back of the wafer during the polishing process, causing particle contamination and, in more serious cases, scratches on the back of the wafer. Extending the polishing head cleaning time after polishing to achieve better cleaning results increases the overall wafer transfer time and reduces the system's output per unit time.

[0004] Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention provides a polishing head cleaning method and cleaning device, which applies a voltage in the opposite direction to the direction when the polishing head is polishing the wafer, and cooperates with an electrolyte fluid to flush the wafer carrying surface, effectively removing charged particle contaminants attached to the wafer carrying surface, with good cleaning effect and short cleaning time.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a polishing head cleaning method, comprising the following steps:

[0007] The polishing head is formed with a conductive wafer carrying surface, and the wafer carrying surface has charged particle contaminants attached thereto;

[0008] applying a voltage to the wafer-carrying surface of the polishing head;

[0009] Electrolyte fluid is delivered to the wafer carrying surface, and the flow of the electrolyte fluid drives the charged particle contaminants to separate from the wafer carrying surface, thereby achieving cleaning of the polishing head.

[0010] Furthermore, when the wafer is polished, a positive voltage is applied to the wafer carrying surface, and when the polishing head is cleaned, a positive voltage or a negative voltage is applied to the wafer carrying surface; or, when the wafer is polished, a negative voltage is applied to the wafer carrying surface, and when the polishing head is cleaned, a negative voltage or a positive voltage is applied to the wafer carrying surface.

[0011] Furthermore, when the wafer is polished, the wafer carrying surface is connected to the positive pole of the power supply, and when the polishing head is cleaned, the wafer carrying surface is connected to the negative pole of the power supply; or, when the wafer is polished, the wafer carrying surface is connected to the positive pole of the power supply, and when the polishing head is cleaned, the wafer carrying surface is also connected to the positive pole of the power supply.

[0012] Furthermore, during wafer polishing, the wafer carrying surface is charged or uncharged.

[0013] Furthermore, in the step of applying voltage to the wafer carrying surface, the voltage is applied continuously, or intermittently, or the voltage is applied in a forward and reverse alternating manner.

[0014] Furthermore, the electrolyte fluid forms a continuous fluid column; the number of the fluid columns is one or two or more.

[0015] Further, the following steps are included:

[0016] The polishing head is formed with a conductive wafer carrying surface, and the wafer carrying surface has charged particle contaminants attached thereto;

[0017] The cleaning seat is formed with a conductive area;

[0018] Electrolyte fluid is transported to the wafer carrying surface and / or the conductive area, and voltage is applied between the polishing head and the cleaning seat so that the electrolyte fluid acts as a conductive medium between the wafer carrying surface and the conductive area. The flow of the electrolyte fluid drives the charged particle contaminants away from the wafer carrying surface, thereby achieving cleaning of the polishing head.

[0019] Furthermore, the method further comprises the step of bringing the polishing head and the cleaning seat closer to each other, with a distance between the two being 0 to 20 mm.

[0020] Furthermore, the polishing head and the cleaning seat can be connected to a power source respectively to form a conductive loop among the wafer supporting surface, the continuous electrolyte fluid, the conductive area, and the power source.

[0021] Furthermore, the electrolyte fluid forms a liquid film on the wafer carrying surface and / or the conductive area, or the electrolyte fluid forms a continuous fluid column between the wafer carrying surface and the conductive area.

[0022] Furthermore, the flow rate of the electrolyte fluid is 200 to 5000 mL / min.

[0023] Furthermore, during the polishing head cleaning step, the polishing head rotates.

[0024] Furthermore, the method further includes the following steps: superimposing ultrasound on the electrolyte fluid.

[0025] Furthermore, after the polishing head is cleaned, the method further includes the step of conveying liquid to the wafer carrying surface and / or the cleaning seat to rinse them.

[0026] Furthermore, the charged particle pollutants are non-metallic and are directionally transferred along with the electrolyte fluid under the action of the electric field; or, the charged particle pollutants are metal.

[0027] Furthermore, the cleaning seat is a polishing table, or the cleaning seat is a wafer carrier, or the cleaning seat is a cleaning table, or the cleaning seat is a cleaning nozzle.

[0028] The present invention also discloses a polishing head cleaning device, comprising:

[0029] A polishing head having a wafer carrying surface, the wafer carrying surface being electrically conductive;

[0030] an electrolyte fluid output unit, configured to output the electrolyte fluid;

[0031] a pressure applying unit, for applying voltage to the wafer bearing surface of the polishing head;

[0032] When charged particle contaminants are attached to the wafer carrying surface, the pressure unit applies voltage to the wafer carrying surface, and the electrolyte fluid output unit transports electrolyte fluid to the wafer carrying surface. The flow of the electrolyte fluid drives the charged particle contaminants away from the wafer carrying surface, thereby cleaning the polishing head.

[0033] Furthermore, when the wafer is polished, a positive voltage is applied to the wafer carrying surface, and when the polishing head is cleaned, a positive voltage or a negative voltage is applied to the wafer carrying surface; or, when the wafer is polished, a negative voltage is applied to the wafer carrying surface, and when the polishing head is cleaned, a negative voltage or a positive voltage is applied to the wafer carrying surface.

[0034] Furthermore, when the wafer is polished, the wafer carrying surface is connected to the positive pole of the power supply, and when the polishing head is cleaned, the wafer carrying surface is connected to the negative pole of the power supply; or, when the wafer is polished, the wafer carrying surface is connected to the positive pole of the power supply, and when the polishing head is cleaned, the wafer carrying surface is also connected to the positive pole of the power supply.

[0035] Furthermore, it also includes a cleaning seat, which is formed with a conductive area. When charged particle contaminants are attached to the wafer carrying surface, the pressure unit applies voltage to the wafer carrying surface and the conductive area. The direction of the voltage is opposite to the direction of the voltage applied to the wafer carrying surface during wafer polishing, and the electrolyte fluid output unit transports electrolyte fluid to the wafer carrying surface. The flow of the electrolyte fluid drives the charged particle contaminants to separate from the wafer carrying surface, thereby achieving cleaning of the polishing head.

[0036] Furthermore, the electrolyte fluid output unit is integrated with the cleaning seat.

[0037] Furthermore, the cleaning seat is a polishing table, or the cleaning seat is a wafer carrier, or the cleaning seat is a cleaning table, or the cleaning seat is a cleaning nozzle; the electrolyte fluid output unit is a cleaning nozzle, or a polishing liquid arm.

[0038] Furthermore, the pressure-applying unit is a power source, and the polishing head and the cleaning seat can be connected to the power source respectively to form a conductive loop between the wafer supporting surface, the continuous electrolyte fluid, the conductive area, and the power source.

[0039] The beneficial effects of the present invention are as follows: 1) voltage is applied to the polishing head to promote charged particle contaminants to separate from the wafer carrying surface of the polishing head, so that the cleaning efficiency of the polishing head is high and the cleaning effect is good; 2) while a negative voltage is applied to the polishing head, the flowing electrolyte fluid continuously rinses the wafer carrying surface, and the cleaning effect is better; 3) during cleaning, the flowing liquid is used for continuous flushing, so that the contaminants can be immediately discharged from the cleaning seat with the liquid, and no secondary pollution will be formed; 4) the entire cleaning process will not affect other components of the polishing device; 5) the polishing head cleaning process can be completed on the polishing pad, or on the wafer carrier, or a separate cleaning device, It can be determined according to needs, with a wide range of choices; 6) When the electrolyte fluid output unit and the cleaning seat are combined into a cleaning nozzle, it can output electrolyte fluid and have a conductive area / ultrasonic area. The electrolyte fluid and current / ultrasound can be simultaneously output to the polishing head. On the basis of the original equipment, no additional equipment will be added, which saves space and makes the cleaning device more controllable; 7) When the electrolyte fluid forms a fluid column, the number of fluid columns can be two or more, so that the polishing head can be cleaned more cleanly. Ultrasonic functions can also be superimposed for different fluid columns, which has higher adaptability. The polishing head can be rotated or not to rotate to complete the cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a simplified structural diagram of the polishing head cleaning device in the first and eighth embodiments of the present invention.

[0041] FIG2 is a simplified structural diagram of a polishing head cleaning device according to a first embodiment of the present invention.

[0042] FIG3 is a simplified structural diagram of a polishing head cleaning device in a third embodiment of the present invention.

[0043] FIG4 is a simplified structural diagram of a polishing head cleaning device according to a sixth embodiment of the present invention.

[0044] FIG5 is a diagram showing the cleaning effect of the present invention, which is represented by the change in resistance of the polishing head with cleaning time.

[0045] FIG6 is a simplified flowchart of the ninth embodiment of the present invention.

[0046] Among them, 1-polishing head, 2-wafer carrying surface, 3-pressure unit, 4-cleaning seat, 41-conductive area, 5-electrolyte fluid, 51-electrolyte fluid output unit, 6-ultrasonic generating device. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0048] A polishing head cleaning method comprises the following steps:

[0049] The polishing head is formed with a conductive wafer carrying surface, and the wafer carrying surface has charged particle contaminants attached thereto;

[0050] applying a voltage to the wafer-carrying surface of the polishing head;

[0051] Electrolyte fluid is delivered to the wafer carrying surface, and the flow of the electrolyte fluid drives the charged particle contaminants to separate from the wafer carrying surface, thereby achieving cleaning of the polishing head.

[0052] Example 1

[0053] A polishing head cleaning method comprises the following steps:

[0054] The polishing head 1 is formed with a conductive wafer carrying surface 2, to which charged particle contaminants are attached. The charged particle contaminants are non-metallic. The wafer carrying surface 2 is made of a conductive material, including metal, conductive polymer, carbon material, and a conductive metal and polymer composite material.

[0055] A voltage is applied to the wafer supporting surface 2 of the polishing head 1, and the direction of the voltage is opposite to the direction of the voltage applied to the wafer supporting surface 2 during wafer polishing. In other words, if the voltage applied to the wafer supporting surface 2 during wafer polishing is defined as a positive voltage, then when the polishing head 1 is cleaning, a negative voltage is applied to the wafer supporting surface 2. More specifically, during wafer polishing, the wafer supporting surface 2 is connected to the positive pole of the power supply, and during cleaning, the wafer supporting surface 2 is connected to the negative pole of the power supply. The voltage applied to the wafer supporting surface 2 can be applied continuously or intermittently, or can be applied in a forward and reverse alternating manner. It can be direct current or alternating current, without specific limitation, and its rated power is ≥50W.

[0056] Of course, in other embodiments, a negative voltage may be applied to the wafer bearing surface 2 during wafer polishing, and a positive voltage may be applied to the wafer bearing surface 2 during cleaning of the polishing head 1, without any specific limitation. As shown in FIG1 , the electrolyte fluid output unit 51 delivers electrolyte fluid 5 to the wafer bearing surface 2. The electrolyte fluid 5 forms a continuous fluid column. The spray angle of the electrolyte fluid 5 is not limited. Specifically, the flow rate of the electrolyte fluid 5 may be 200 to 5000 mL / min. The flow of the electrolyte fluid 5 drives the charged particle contaminants to separate from the wafer bearing surface 2. That is, when the charged particle contaminants are non-metallic, they move in a directional manner under the action of the electric field and move in a directional manner with the electrolyte fluid 5 to separate from the wafer bearing surface 2, thereby achieving cleaning of the polishing head 1. The cleaning duration is 30 to 120 seconds.

[0057] The number of the above-mentioned fluid columns can be one or two or more, without specific limitation;

[0058] Ultrasonic waves can also be superimposed on the electrolyte fluid to enhance the cleaning effect by utilizing ultrasonic oscillation, as shown in FIG2 , where an ultrasonic generating device 6 is provided;

[0059] Of course, the charged particle contaminants can also be metals, which are carried away from the wafer carrying surface by the flow of the electrolyte fluid;

[0060] In the above process, the polishing head can be stationary or rotating.

[0061] After the polishing head is cleaned, liquid can continue to be transported to the wafer carrying surface to rinse it. The liquid can be deionized water or cleaning liquid. The cleaning liquid can be an inorganic acid aqueous solution, an inorganic alkali aqueous solution, or an inorganic salt aqueous solution, so as to avoid the accumulation of impurities and secondary contamination of the polishing head during cleaning.

[0062] As shown in Figure 5, for a polishing head with a conductive wafer-carrying surface, the surface resistance is greater than 10 MΩ after a long period of polishing. Even after rinsing with deionized water alone for 60 seconds, the resistance of the wafer-carrying surface of the polishing head is still greater than 10 MΩ. However, after only 60 seconds of DC and ultrasonic cleaning, the resistance of the wafer-carrying surface of the polishing head is less than 10 Ω.

[0063] Example 2

[0064] The difference from Example 1 is that a voltage is applied to the wafer carrying surface 2 of the polishing head 1, and the direction of the voltage is the same as the direction of the voltage applied to the wafer carrying surface 2 during wafer polishing. In other words, if the voltage applied to the wafer carrying surface 2 during wafer polishing is defined as a forward voltage, then at this time the polishing head 1 is cleaned and a forward voltage is applied to the wafer carrying surface 2.

[0065] More specifically, when the wafer is polished, the wafer carrying surface 2 is connected to the positive pole of the power supply, and when the polishing head 1 is cleaned, the wafer carrying surface 2 is also connected to the positive pole of the power supply.

[0066] The rest is the same as that of the first embodiment and will not be described in detail.

[0067] Example 3

[0068] A polishing head cleaning method comprises the following steps:

[0069] The polishing head 1 is formed with a conductive wafer carrying surface 2, and the wafer carrying surface 2 is attached with charged particle contaminants, and the charged particle contaminants are non-metallic;

[0070] The cleaning seat 4 is formed with a conductive area 41; the cleaning seat can be a polishing table, or the cleaning seat is a wafer stage, or the cleaning seat is a cleaning table, or the cleaning seat is a cleaning nozzle, and there is no specific limitation, as long as the cleaning seat has a conductive area;

[0071] As shown in FIG3 , an electrolyte fluid 5 is transported to the wafer carrying surface 2 so that the electrolyte fluid 5 forms a liquid film on the wafer carrying surface 2 , and the polishing head 1 and the cleaning seat 4 are close to each other, with a distance between them ranging from 0 to 20 mm, that is, the polishing head 1 and the cleaning seat 4 may or may not be in contact. At this time, the conductive area 41 of the cleaning seat 4 is in contact with the liquid film formed by the electrolyte fluid 5, that is, the electrolyte fluid 5 fills the gap between the polishing head 1 and the cleaning seat 4. A voltage is applied between the polishing head 1 and the cleaning seat 4. In other words, a direct current or alternating current is applied between the polishing head 1 and the cleaning seat 4 so that the electrolyte fluid 5 serves as a conductive medium between the wafer carrying surface 2 and the conductive area 41. The flow of the electrolyte fluid 5 drives the charged particle contaminants to separate from the wafer carrying surface 2, thereby achieving cleaning of the polishing head 1. The cleaning duration is 30 to 120 seconds.

[0072] The voltage applied to the wafer supporting surface 2 during wafer polishing is defined as a positive voltage. The voltage applied at this time can be a positive voltage, a negative voltage, or a positive voltage and a negative voltage applied alternately.

[0073] More specifically, when cleaning impurities that have flowed into the gap between the wafer and the conductive cloth after the reaction, a positive voltage is applied. At this time, the impurities are usually positively charged. During cleaning, the positive voltage can be used to drive the impurities away from the polishing head and move them toward the cleaning seat to achieve cleaning. When cleaning impurities that are electrostatically adsorbed on the polishing head, these impurities are negatively charged. During cleaning, the polishing head needs to be switched to a negative voltage drive, and the cleaning seat is positively charged. At this time, the negatively charged impurities on the polishing head will move toward the cleaning seat to achieve cleaning. Of course, positive and negative voltages can be applied separately during the same cleaning process to clean different types of impurities, making the polishing head clean more thoroughly.

[0074] Ultrasonic waves can also be superimposed on the electrolyte fluid to enhance the cleaning effect by using ultrasonic vibrations;

[0075] In the above process, the polishing head can be stationary or rotating.

[0076] After the polishing head is cleaned, liquid can continue to be transported to the wafer carrying surface and the cleaning seat to rinse them. The liquid can be deionized water or a cleaning liquid. The cleaning liquid can be an inorganic acid aqueous solution, an inorganic alkali aqueous solution, or an inorganic salt aqueous solution, so as to avoid the accumulation of impurities and secondary contamination of the polishing head during cleaning.

[0077] Example 4

[0078] The difference from Example 3 is that the electrolyte fluid is transported in the conductive area, so that the electrolyte fluid forms a liquid film in the conductive area, and the polishing head and the cleaning seat are close to each other, with a distance between them between 0 and 20 mm. At this time, the wafer carrying surface of the polishing head is in contact with the liquid film formed by the electrolyte fluid, and a voltage is applied between the polishing head and the cleaning seat so that the electrolyte fluid serves as a conductive medium between the wafer carrying surface and the conductive area. The flow of the electrolyte fluid drives the charged particle contaminants to leave the wafer carrying surface, thereby achieving cleaning of the polishing head.

[0079] The rest is the same as that of the third embodiment and will not be described in detail.

[0080] Example 5

[0081] The difference from Example 3 is that electrolyte fluid is transported to both the wafer carrying surface and the conductive area, so that the electrolyte fluid forms a liquid film in the conductive area and a liquid film on the wafer carrying surface, and the polishing head and the cleaning seat are close to each other, with a distance between them between 0 and 20 mm. At this time, the liquid film on the wafer carrying surface contacts the liquid film in the conductive area, and a voltage is applied between the polishing head and the cleaning seat so that the electrolyte fluid serves as a conductive medium between the wafer carrying surface and the conductive area. The flow of the electrolyte fluid drives the charged particle contaminants away from the wafer carrying surface, thereby achieving cleaning of the polishing head.

[0082] The rest is the same as that of the second embodiment and will not be described in detail.

[0083] Example 6

[0084] The difference from the third embodiment is that the electrolyte fluid 5 forms a continuous fluid column between the wafer carrying surface 2 and the conductive area 41 , as shown in FIG4 , and the flow rate of the electrolyte fluid 5 can be 200 to 5000 mL / min.

[0085] Specifically, the electrolyte fluid 5 may be transported to the wafer carrying surface 2 , and the electrolyte fluid 5 continues to flow toward the conductive region 41 after passing through the wafer carrying surface 2 , thereby forming a continuous fluid column between the wafer carrying surface 2 and the conductive region 41 .

[0086] Alternatively, the electrolyte fluid 5 is transported to the conductive region 41 , and the electrolyte fluid 5 continues to flow toward the wafer carrying surface 2 after passing through the conductive region 41 , thereby forming a continuous fluid column between the conductive region 41 and the wafer carrying surface 2 .

[0087] Example 7

[0088] In Examples 3 to 6, the specific method of applying voltage between the polishing head and the cleaning seat is not limited. In this embodiment, the polishing head and the cleaning seat can be connected to the positive and negative poles of the power supply respectively to form a conductive circuit between the wafer supporting surface, the continuous electrolyte fluid, the conductive area, and the power supply.

[0089] Specifically, the cleaning seat has a wiring seat connected to a power supply, which can form a circuit with the polishing head which is also connected to the power supply.

[0090] Example 8

[0091] A polishing head cleaning device, comprising:

[0092] As shown in FIG1 , a polishing head 1 has a wafer carrying surface 2 , and the wafer carrying surface 2 is conductive;

[0093] The electrolyte fluid output unit 51 is used to output the electrolyte fluid 5; the electrolyte fluid output by the electrolyte fluid output unit 51 can be distributed on the wafer carrying surface 2 in the form of points, lines, or surfaces;

[0094] A pressure-applying unit 3 is used to apply voltage to the wafer-carrying surface 2 of the polishing head 1; in this embodiment, the pressure-applying unit 3 is a power source;

[0095] When charged particle contaminants are attached to the wafer carrying surface 2, the pressure unit 3 applies a voltage to the wafer carrying surface 2. The direction of the voltage is opposite to the direction of the voltage applied to the wafer carrying surface 2 during wafer polishing, and the electrolyte fluid output unit 51 transports the electrolyte fluid 5 to the wafer carrying surface 2. The flow of the electrolyte fluid 5 drives the charged particle contaminants to separate from the wafer carrying surface, thereby achieving cleaning of the polishing head.

[0096] Embodiment 9

[0097] The difference between this embodiment and the eighth embodiment is that the pressure applying unit 3 applies a voltage to the wafer carrying surface 2 , and the direction of the voltage is the same as the direction of the voltage applied to the wafer carrying surface 2 during wafer polishing.

[0098] Of course, the pressure applying unit 3 may first apply a positive voltage to the wafer supporting surface 2 and then apply a negative voltage; or first apply a negative voltage and then apply a positive voltage; or alternately apply a positive voltage and a negative voltage. The above description is based on the definition that the voltage applied to the wafer supporting surface 2 during wafer polishing is a positive voltage.

[0099] Example 10

[0100] In the eighth and ninth embodiments, the wafer supporting surface 2 is charged during wafer polishing. In this embodiment, the wafer supporting surface 2 is not charged, that is, the wafer is not charged during polishing. At this time, the pressure unit 3 applies a positive voltage or a negative voltage.

[0101] Example 11

[0102] A polishing head cleaning device, comprising:

[0103] The polishing head 1 has a wafer carrying surface 2, and the wafer carrying surface 2 is conductive;

[0104] The cleaning seat 4 is formed with a conductive area 41; the cleaning seat can be a polishing table, or the cleaning seat is a wafer carrier, or the cleaning seat is a cleaning table, or the cleaning seat is a cleaning nozzle, and there is no specific limitation, as long as the cleaning seat has a conductive area;

[0105] The cleaning seat may include an ultrasonic generator 6, through which ultrasonic waves are superimposed on the electrolyte fluid and then transmitted to the wafer supporting surface through the electrolyte fluid;

[0106] The electrolyte fluid output unit 51 is used to output the electrolyte fluid 5; the electrolyte fluid output unit 51 is a cleaning nozzle, or a polishing liquid arm; of course, the electrolyte fluid output unit and the cleaning seat can also be integrated;

[0107] A pressure-applying unit 3 is used to apply voltage to the wafer-carrying surface 2 of the polishing head 1. In this embodiment, the pressure-applying unit is a power supply, and the polishing head and the cleaning seat can be connected to the power supply respectively.

[0108] When charged particle contaminants are attached to the wafer carrying surface 2, the pressure unit 3 applies voltage to the wafer carrying surface 2 and the conductive area 41, thereby forming a conductive circuit between the wafer carrying surface 2, the continuous electrolyte fluid 5, the conductive area 41, and the power supply. The direction of the voltage is opposite to the direction of the voltage applied to the wafer carrying surface 2 during wafer polishing, and the electrolyte fluid output unit 51 transports the electrolyte fluid 5 to the wafer carrying surface 2. The flow of the electrolyte fluid 5 drives the charged particle contaminants to separate from the wafer carrying surface 2, thereby achieving the cleaning of the polishing head 1.

[0109] In this embodiment, the electrolyte fluid output unit and the cleaning seat can also be combined into one.

[0110] More specifically, as shown in FIG6 , the following steps are included:

[0111] S1. The polishing head stops right above the cleaning seat;

[0112] S2, the polishing head descends or the cleaning seat ascends, and the wafer loading surface of the polishing head approaches or contacts the conductive area of ​​the cleaning seat;

[0113] S3. When cleaning begins, the polishing head starts to rotate, and the cleaning seat (in this case, the electrolyte fluid output unit and the cleaning seat are integrated) sprays the electrolyte fluid. At the same time, a DC or AC voltage is applied between the polishing head and the cleaning seat to improve the cleaning efficiency. Of course, during this process, the polishing head may not rotate, and the cleaning seat may spray the electrolyte fluid over a sufficiently wide range, or its spraying direction may be changed by rotation.

[0114] S4. After the cleaning process is completed, the cleaning seat sprays deionized water to rinse the wafer loading surface of the polishing head and the cleaning seat;

[0115] S5. After the polishing head is cleaned, the polishing head moves away from the cleaning seat;

[0116] S6. Spray deionized water on the cleaning seat to rinse the conductive area of ​​the cleaning seat.

[0117] The above specific embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A polishing head cleaning method, characterized in that, Including the following steps: The polishing head is formed with a conductive wafer carrying surface, and charged particle contaminants are attached to the wafer carrying surface; Apply a voltage to the wafer carrying surface of the polishing head; Convey an electrolyte fluid to the wafer carrying surface, and the flowing electrolyte fluid drives the charged particle contaminants to break away from the wafer carrying surface, realizing the cleaning of the polishing head.

2. The polishing head cleaning method according to claim 1, characterized in that: When polishing the wafer, a positive voltage is applied to the wafer carrying surface. Then, when cleaning the polishing head, a positive voltage or a negative voltage is applied to the wafer carrying surface; or, when polishing the wafer, a negative voltage is applied to the wafer carrying surface. Then, when cleaning the polishing head, a negative voltage or a positive voltage is applied to the wafer carrying surface.

3. The polishing head cleaning method according to claim 1 or 2, characterized in that: When polishing the wafer, the wafer carrying surface is connected to the positive electrode of the power supply. When cleaning the polishing head, the wafer carrying surface is connected to the negative electrode of the power supply; or, when polishing the wafer, the wafer carrying surface is connected to the positive electrode of the power supply. When cleaning the polishing head, the wafer carrying surface is also connected to the positive electrode of the power supply.

4. The polishing head cleaning method according to claim 1, characterized in that: When polishing the wafer, the wafer carrying surface is charged or uncharged.

5. The polishing head cleaning method according to claim 1 or 2 or 4, characterized in that: In the step of applying a voltage to the wafer carrying surface, the voltage is applied continuously, or intermittently, or the voltage is applied with positive and negative alternations.

6. The polishing head cleaning method according to claim 1 or 2 or 4, characterized in that: The electrolyte fluid forms a continuous fluid column; the number of the fluid columns is one or two or more.

7. The polishing head cleaning method according to claim 1, wherein: Including the following steps, The polishing head is formed with a conductive wafer carrying surface, and charged particle contaminants are attached to the wafer carrying surface; The cleaning base is formed with a conductive area; Convey the electrolyte fluid on the wafer carrying surface or / and the conductive area, and apply a voltage between the polishing head and the cleaning base so that the electrolyte fluid serves as a conductive medium between the wafer carrying surface and the conductive area. The flowing electrolyte fluid drives the charged particle contaminants to break away from the wafer carrying surface, realizing the cleaning of the polishing head.

8. The polishing head cleaning method according to claim 7, characterized in that: It further includes the step of bringing the polishing head and the cleaning base closer to each other, and the distance between the two is 0 - 20 mm.

9. The polishing head cleaning method according to claim 7, characterized in that: The polishing head and the cleaning base can be respectively connected to the power supply to form a conductive loop among the wafer carrying surface, the continuous electrolyte fluid, the conductive area, and the power supply.

10. The polishing head cleaning method according to claim 7, characterized in that: The electrolyte fluid forms a liquid film on the wafer carrying surface or / and the conductive area, or the electrolyte fluid forms a continuous fluid column between the wafer carrying surface and the conductive area.

11. The polishing head cleaning method according to claim 1 or 10, characterized in that: The flow rate of the electrolyte fluid is 200 - 5000 mL / min.

12. The polishing head cleaning method according to claim 1 or 7, characterized in that: In the step of cleaning the polishing head, the polishing head rotates.

13. The polishing head cleaning method according to claim 1 or 7, characterized in that: It further includes the following step of superimposing ultrasonic waves on the electrolyte fluid.

14. The polishing head cleaning method according to claim 1 or 7, characterized in that: After the cleaning of the polishing head, it further includes the step of conveying a liquid to the wafer carrying surface and / or the cleaning base to rinse them.

15. The polishing head cleaning method according to claim 1 or 7, characterized in that: The charged particle contaminants are non-metallic and are directionally transferred with the electrolyte fluid under the action of an electric field; or, the charged particle contaminants are metallic.

16. The polishing head cleaning method according to claim 7, wherein: The cleaning base is a polishing table, or a wafer stage, or a cleaning table, or a cleaning nozzle.

17. A polishing head cleaning device, characterized in that, Including: A polishing head having a wafer carrying surface that is conductive; An electrolyte fluid output unit for outputting an electrolyte fluid; A pressure application unit for applying a voltage to the wafer carrying surface of the polishing head; When charged particle contaminants adhere to the wafer carrying surface, the pressure applying unit applies a voltage to the wafer carrying surface, and the electrolyte fluid output unit conveys an electrolyte fluid to the wafer carrying surface. The flow of the electrolyte fluid drives the charged particle contaminants away from the wafer carrying surface, achieving the cleaning of the polishing head.

18. The polishing head cleaning device according to claim 17, wherein: During wafer polishing, a positive voltage is applied to the wafer carrying surface. Then, during polishing head cleaning, a positive voltage or a negative voltage is applied to the wafer carrying surface; or, during wafer polishing, a negative voltage is applied to the wafer carrying surface. Then, during polishing head cleaning, a negative voltage or a positive voltage is applied to the wafer carrying surface.

19. The polishing head cleaning device according to claim 17 or 18, characterized in that: During wafer polishing, the wafer carrying surface is connected to the positive electrode of the power supply. During polishing head cleaning, the wafer carrying surface is connected to the negative electrode of the power supply; or, during wafer polishing, the wafer carrying surface is connected to the positive electrode of the power supply. During polishing head cleaning, the wafer carrying surface is also connected to the positive electrode of the power supply.

20. The polishing head cleaning device according to claim 17, wherein: It further includes a cleaning base which is formed with a conductive area. When charged particle contaminants adhere to the wafer carrying surface, the pressure applying unit applies a voltage to the wafer carrying surface and the conductive area. The direction of this voltage is opposite to the voltage direction applied to the wafer carrying surface during wafer polishing. And the electrolyte fluid output unit conveys an electrolyte fluid to the wafer carrying surface. The flow of the electrolyte fluid drives the charged particle contaminants away from the wafer carrying surface, achieving the cleaning of the polishing head.

21. The polishing head cleaning device according to claim 20, characterized in that: The electrolyte fluid output unit is integrally provided with the cleaning base.

22. The polishing head cleaning device according to claim 20, wherein: The cleaning base is a polishing table, or the cleaning base is a wafer stage, or the cleaning base is a cleaning table, or the cleaning base is a cleaning nozzle; The electrolyte fluid output unit is a cleaning nozzle or a polishing fluid arm.

23. The polishing head cleaning device according to claim 20, wherein: The pressure applying unit is a power supply. The polishing head and the cleaning base can be respectively connected to the power supply to form a conductive loop among the wafer carrying surface, the continuous electrolyte fluid, the conductive area, and the power supply.

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