A method and apparatus for cleaning a polishing pad

Abstract

This invention discloses a method and apparatus for cleaning a polishing pad. The method may include: when a high-pressure cleaning nozzle sprays deionized water at a set angle onto a target area on the polishing pad, a pressure sensor located at a set position above the polishing pad senses the pressure value of the reflected water flow; corresponding to a pressure value of the reflected water flow being greater than a set first pressure threshold, the duration of the high-pressure cleaning nozzle spraying deionized water onto the target area is extended; corresponding to a pressure value of the reflected water flow being less than a set second pressure threshold, the high-pressure cleaning nozzle is moved to spray deionized water onto the next area of ​​the target area.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method and apparatus for cleaning polishing pads. Background Technology

[0002] In semiconductor manufacturing technology, surface planarization is a crucial technique for high-density photolithography. A smooth, even surface prevents scattering during exposure, enabling precise pattern transfer. Chemical mechanical polishing (CMP) is a commonly used technique for achieving global planarization. This method involves bringing the wafer into contact with a rotating polishing pad and applying pressure, using a chemical polishing slurry to planarize the wafer. In other words, CMP is a mechanical polishing process primarily based on chemical reactions. Currently, CMP is the standard method for planarization in wafer fabrication.

[0003] It should be noted that polishing pads are typically porous polymer surfaces, such as foamed materials. Therefore, during polishing, powder removed from the wafer surface easily combines with the polishing slurry and is squeezed into the pores of the polishing pad. As the polishing process continues, a glaze layer gradually forms on the polishing pad surface. If not cleaned promptly, this glaze layer will expand, resulting in uneven surface roughness and hardness. This leads to variations in polishing results even under the same polishing procedure. Furthermore, if the accumulated glaze layer becomes increasingly hard, it can even scratch the wafer surface. Therefore, in current CMP processes, the polishing pad surface is typically rinsed with high-pressure deionized water after each batch of wafers has been polished to remove the glaze layer and restore the surface to its porous state. Therefore, improving the cleaning effectiveness of polishing pads is a problem that needs to be addressed. Summary of the Invention

[0004] In view of this, embodiments of the present invention aim to provide a method and apparatus for cleaning polishing pads; by reducing the cumulative effect of the glaze layer on the surface of the polishing pad, the cleaning effect of the polishing pad is improved, and ultimately the polishing flatness of the polishing pad in the CMP process is improved and the possibility of scratching the wafer surface in the CMP process is reduced.

[0005] The technical solution of this invention is implemented as follows:

[0006] In a first aspect, embodiments of the present invention provide a method for cleaning a polishing pad, the method comprising:

[0007] When the high-pressure cleaning nozzle sprays deionized water at a set angle onto the target area of ​​the polishing pad, a pressure sensor located at a set position above the polishing pad senses the pressure value of the reflected water flow; wherein, the reflected water flow is formed by the deionized water flow being reflected by the target area;

[0008] If the pressure value of the reflected water flow is greater than the set first pressure threshold, the duration for which the high-pressure cleaning nozzle sprays deionized water flow onto the target area is extended.

[0009] When the pressure value of the reflected water flow is less than a set second pressure threshold, the high-pressure cleaning nozzle is moved to spray deionized water into the next area of ​​the target area; wherein the second pressure threshold is less than the first pressure threshold.

[0010] Secondly, embodiments of the present invention provide an apparatus for cleaning polishing pads, the apparatus comprising:

[0011] High-pressure cleaning arm;

[0012] A high-pressure cleaning nozzle is provided at one end of the high-pressure cleaning arm. The spray direction of the high-pressure cleaning nozzle can be adjusted to spray deionized water into the target area on the polishing pad at a set angle.

[0013] A moving motor located at the other end of the high-pressure cleaning arm controls the movement of the high-pressure cleaning arm to drive the movement of the high-pressure cleaning nozzle.

[0014] A pressure sensor is positioned at a predetermined distance from the high-pressure cleaning nozzle and above the polishing pad to sense the pressure value of the reflected water flow; wherein the reflected water flow is formed by the deionized water flow reflecting off the target area;

[0015] The controller is used to extend the duration of the high-pressure cleaning nozzle spraying deionized water into the target area by controlling the working state of the moving motor when the pressure value of the reflected water flow is greater than a set first pressure threshold.

[0016] When the pressure value of the reflected water flow is less than a set second pressure threshold, the high-pressure cleaning nozzle is moved by controlling the working state of the moving motor to spray deionized water into the next area of ​​the target area; wherein the second pressure threshold is less than the first pressure threshold.

[0017] This invention provides a method and apparatus for cleaning a polishing pad. During the cleaning process, the pressure value of the reflected water flow is detected, and different degrees of cleaning operations are performed according to the degree of glazing corresponding to the pressure value, thereby achieving complete removal of the glaze layer, improving the cleaning effect of the polishing pad, and thus improving the polishing flatness of the polishing pad in the CMP process and reducing the possibility of scratching the wafer surface in the CMP process. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the original state of the surface of a polishing pad provided in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of a polishing pad surface after glazing, provided in an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the composition of a device for cleaning and polishing pads provided in an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of a polishing pad with a glazed layer on its surface, provided in an embodiment of the present invention, showing a reflected water flow.

[0022] Figure 5 This is a schematic diagram of reflected water flow on the surface of a polishing pad in its initial state, provided as an embodiment of the present invention.

[0023] Figure 6 A schematic diagram illustrating the composition of another device for cleaning and polishing pads provided in an embodiment of the present invention;

[0024] Figure 7 Top view of the apparatus for cleaning and polishing pads provided in an embodiment of the present invention.

[0025] Figure 8 This is a schematic flowchart of a method for cleaning a polishing pad provided in an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] See Figure 1 This diagram shows an enlarged cross-sectional view of the initial surface of a polishing pad in its unused state. Typically, the surface of a polishing pad is a porous polymer surface, such as a foamed material, designed to hold polishing slurry and deliver abrasive particles from the slurry to the wafer surface for planarization by rotating and removing micro-protrusions. Figure 1As shown, the surface 1 of the polishing pad is not flat, but rather undulating and rough. During use, as the polishing process continues, the powder removed from the wafer surface by polishing easily combines with the polishing fluid and is squeezed into the pores on the surface of the polishing pad, thus gradually forming a glaze layer 2 on the surface of the polishing pad, such as... Figure 2 As shown by the dotted line, this glaze layer causes the polishing pad surface to lose its original roughness, becoming smoother, thus worsening the polishing flatness of the pad. Therefore, it is necessary to periodically rinse the polishing pad surface with high-pressure deionized water to remove the glaze layer and restore the polishing pad surface to its porous state. It should be noted that... Figure 2 As shown by the dashed line, the degree of glazing is inconsistent in different areas of the polishing pad. If the current conventional rinsing method is followed, and the high-pressure cleaning nozzle is moved at a fixed speed and rinsed at a fixed water pressure, it will be impossible to thoroughly clean the glazing layer in different areas of the polishing pad, and thus it will be impossible to effectively restore the surface of the polishing pad to its initial state.

[0028] To avoid the above situation, please refer to Figure 3 This invention aims to provide a device 3 for cleaning polishing pads. The device 3 may include: a high-pressure cleaning arm 31; and a high-pressure cleaning nozzle 32 disposed at one end of the high-pressure cleaning arm 31, wherein the spray direction of the high-pressure cleaning nozzle 32 is adjustable. Figure 3 As indicated by the dashed arrow, a deionized water stream is sprayed onto the target area on the polishing pad 4 at a set angle. A moving motor 33, located at the other end of the high-pressure cleaning arm 31, controls the movement of the high-pressure cleaning arm 31 to drive the movement of the high-pressure cleaning nozzle 32. A pressure sensor 34, positioned at a set distance from the high-pressure cleaning nozzle 32 and above the polishing pad 4, senses the pressure value of the reflected water stream. The reflected water stream is formed by the deionized water stream reflecting off the target area. In some examples, the pressure sensor 34 can be located on the high-pressure cleaning arm 31, and can be positioned on the high-pressure cleaning arm 31 near the moving motor 33 or away from the moving motor 33, depending on the spray angle of the deionized water from the high-pressure cleaning nozzle 32. To clearly and concisely illustrate the technical solution, this embodiment of the invention uses... Figure 3 The example shown is an externally positioned component. Furthermore, it includes a controller 35, configured to extend the duration of the high-pressure cleaning nozzle 32 spraying deionized water onto the target area by controlling the operation of the moving motor 33 when the pressure value of the reflected water flow is greater than a set first pressure threshold; and to move the high-pressure cleaning nozzle 32 to spray deionized water onto the next area of ​​the target area by controlling the operation of the moving motor 33 when the pressure value of the reflected water flow is less than a set second pressure threshold; wherein the second pressure threshold is less than the first pressure threshold.

[0029] Specifically, the controller 35 can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly manifested as being executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor.

[0030] It is understood that the above components are only essential components for implementing the embodiments of the present invention. In specific implementation, the device 3 for cleaning the polishing pad may also include... Figure 3 Other components not shown, such as the support platform for the polishing pad 4, will not be described in detail in this embodiment of the invention. In addition, the controller 35 controls the moving motor 33 to move the high-pressure cleaning arm 31 along a set moving path, thereby causing the high-pressure cleaning nozzle 32 mounted on the high-pressure cleaning arm 31 to also move along the same moving path. This moving path can cover the entire area of ​​the polishing pad 4, thereby achieving complete cleaning of the entire area of ​​the polishing pad 4.

[0031] It should be noted that the deionized water sprayed through the high-pressure cleaning nozzle 32 will be reflected after passing over the surface of the polishing pad 4. The pressure value of the reflected water flow is related to the surface morphology of the polishing pad 4. For example, see... Figure 4 If an exemplary area on the surface of polishing pad 4 is in such a state Figure 2 In the fully glazed state shown, because the glazed layer 2 is relatively smooth, the sprayed deionized water, as indicated by the solid arrow, will produce a high-volume reflected water stream when passing through the glazed layer 2, such as... Figure 4 As indicated by the dashed arrow, this phenomenon shows that the higher the degree of glazing, the greater the pressure of the reflected water flow. Correspondingly, this area of ​​polishing pad 4 should be cleaned more thoroughly. (See also...) Figure 5 If an exemplary area on the surface of polishing pad 4 is in Figure 1 In the initial state shown, the solid arrow indicates that the sprayed deionized water passing through the porous foam material does not produce a highly reflected water flow, and the volume of the reflected water flow is small. Figure 5As shown by the dashed arrow, this phenomenon indicates that the lower the degree of glazing, the lower the pressure of the reflected water flow. Accordingly, this area of ​​the polishing pad 4 does not need to be thoroughly cleaned, or even cleaned at all.

[0032] exist Figure 3 In the technical solution shown, the first pressure threshold is used to characterize the degree of severe glazing on the surface of the polishing pad 4. When the pressure value of the reflected water flow is greater than the first pressure threshold, it indicates that the surface glazing of the polishing pad 4 in the target area is relatively high and needs to be cleaned thoroughly. At this time, the duration of the high-pressure cleaning nozzle 32 spraying deionized water flow into the target area can be extended to achieve thorough cleaning. In some examples, the controller 35 can reduce the moving speed of the high-pressure cleaning nozzle 32 in the space above the target area by reducing the power of the moving motor 33, thereby extending the duration of the high-pressure cleaning nozzle 32 spraying deionized water flow into the target area.

[0033] In addition, thorough cleaning of the target area can be achieved by increasing water pressure; based on this, see [link to relevant documentation]. Figure 6 In some examples, the device 3 further includes a deionized water supply section 36, which can be connected to the high-pressure cleaning nozzle 32 via a liquid transport pipe 37, thereby providing the high-pressure cleaning nozzle 32 with deionized water at a set pressure; for the deionized water supply section 36, when the pressure value of the reflected water flow is greater than a first pressure threshold, the controller 35 can also increase the water pressure of the deionized water supplied by the deionized water supply section 36 to the high-pressure cleaning nozzle 32 to increase the water pressure of the deionized water flow sprayed by the high-pressure cleaning nozzle 32 onto the target area.

[0034] exist Figure 3 In the illustrated technical solution, the second pressure threshold is used to characterize that the surface of the polishing pad 4 has no glaze layer and has recovered to a state similar to... Figure 1 The initial state is shown. Understandably, after being cleaned by the deionized water sprayed from the high-pressure cleaning nozzle 32, when the pressure of the reflected water flow is less than the second pressure threshold, it indicates that the surface of the polishing pad 4 in the target area has returned to its initial state, and there is no need to continue cleaning the target area. Therefore, the controller 35 can control the moving motor 33 to move the high-pressure cleaning arm 31, thereby driving the high-pressure cleaning nozzle 32 to move to the next area of ​​the target area for cleaning by spraying deionized water.

[0035] exist Figure 3In the technical solution shown, when the pressure value of the reflected water flow is between the first pressure threshold and the second pressure threshold, it indicates that the degree of glazing in the target area is not serious and can be cleaned according to the conventional method. In some examples, corresponding to the pressure value of the reflected water flow being less than the first pressure threshold and greater than the second pressure threshold, the controller 35 can change the power of the moving motor to make the high-pressure cleaning nozzle move in the space above the target area at the initial moving speed.

[0036] In addition, similar to the examples mentioned above, water pressure can also be controlled, as in some examples, such as Figure 6 As shown, the device 3 further includes a deionized water supply section 36, which can be connected to the high-pressure cleaning nozzle 32 via a liquid transport pipe 37, thereby providing the high-pressure cleaning nozzle 32 with deionized water at a set pressure. Regarding this deionized water supply section 36, when the pressure value of the reflected water flow is between a first pressure threshold and a second pressure threshold, the controller 35 can set the water pressure of the deionized water supplied by the deionized water supply section 36 to the high-pressure cleaning nozzle 32 according to a set water pressure range, so as to maintain the water pressure of the deionized water flow sprayed by the high-pressure cleaning nozzle 32 onto the target area within the set water pressure range. It can be understood that this water pressure range allows cleaning to be performed when the glaze on the polishing pad surface is not severely enamelized.

[0037] Furthermore, in the process of implementing the above technical solutions by those skilled in the art, multiple pressure thresholds can be set between the first pressure threshold and the second pressure threshold to characterize different degrees of glazing, thereby setting the corresponding spray deionized water flow duration and / or deionized water flow pressure for different degrees of glazing. The embodiments of the present invention will not elaborate further.

[0038] Based on the aforementioned device 3 for cleaning and polishing pads, the specific cleaning process of this device 3 is described below. (See attached document.) Figure 7 The top view of device 3 shown indicates that the specific cleaning process may include:

[0039] First, the moving motor 33 moves the high-pressure cleaning arm 31, which in turn drives the high-pressure cleaning nozzle 32 to move above the target area of ​​the polishing pad 4 shown in the dashed box.

[0040] Next, the high-pressure cleaning nozzle 32 sprays deionized water toward the target area at a certain angle. At this time, the pressure sensor 34, which is also set above the polishing pad and at a set distance from the high-pressure cleaning nozzle 32, senses the pressure value of the reflected water flow formed after the deionized water flow is reflected by the target area, and transmits the pressure value to the controller 35.

[0041] Then, the controller 35 compares the pressure value transmitted by the pressure sensor 34 with the first pressure threshold:

[0042] When the pressure of the reflected water flow is greater than the first pressure threshold, according to the relevant description of the aforementioned technical solution, the controller 35 can reduce the power of the moving motor 33 to reduce the moving speed of the high-pressure cleaning arm 31, thereby slowing down the moving speed of the high-pressure cleaning nozzle 32 and increasing the cleaning time of the target area. It should be noted that increasing the cleaning time can thoroughly clean the glaze layer. In addition, in this embodiment of the invention, the controller 35 can also achieve thorough cleaning of the glaze layer by increasing the water pressure of the deionized water sprayed by the high-pressure cleaning nozzle 32.

[0043] When the pressure of the reflected water flow is less than the second pressure threshold, according to the aforementioned technical solution, the glaze layer of the target area has been cleaned, and the polishing pad 4 has returned to its initial unused state on the surface of the target area. At this point, the target area does not need to be cleaned further. Therefore, the controller 35 can control the moving motor 33 to move the high-pressure cleaning arm 31 to drive the high-pressure cleaning nozzle 32 to move above the next area of ​​the target area shown in the dotted box, and continue cleaning the next area according to the above process.

[0044] The above technical solution detects the pressure value of the reflected water flow during the cleaning of the polishing pad, and performs different cleaning operations according to the degree of glazing corresponding to the pressure value, thereby achieving complete removal of the glaze layer, improving the cleaning effect of the polishing pad, and thus improving the polishing flatness of the polishing pad in the CMP process and reducing the possibility of scratching the wafer surface in the CMP process.

[0045] The device 3 for cleaning and polishing pads based on the above technical solution, see [link to device 3]. Figure 8 This invention illustrates a method for cleaning a polishing pad according to an embodiment of the present invention, the method comprising:

[0046] S81: When the high-pressure cleaning nozzle sprays deionized water at a set angle onto the target area on the polishing pad, the pressure value of the reflected water flow is sensed by a pressure sensor set at a set position above the polishing pad.

[0047] The reflected water flow is formed by the deionized water flow reflecting off the target area;

[0048] S82: When the pressure value of the reflected water flow is greater than the set first pressure threshold, extend the duration for which the high-pressure cleaning nozzle sprays deionized water flow toward the target area;

[0049] S83: When the pressure value of the reflected water flow is less than the set second pressure threshold, the high-pressure cleaning nozzle is moved to spray deionized water into the next area of ​​the target area; wherein the second pressure threshold is less than the first pressure threshold.

[0050] In some examples, where the pressure value corresponding to the reflected water flow is greater than a set first pressure threshold, the method further includes:

[0051] Increase the water pressure of the deionized water jet sprayed from the high-pressure cleaning nozzle onto the target area.

[0052] In some examples, extending the duration for which the high-pressure cleaning nozzle sprays deionized water onto the target area includes:

[0053] Reduce the moving speed of the high-pressure cleaning nozzle in the space above the target area.

[0054] In some examples, where the pressure value corresponding to the reflected water flow is less than the first pressure threshold and greater than the second pressure threshold, the method further includes:

[0055] The high-pressure cleaning nozzle moves within the space above the target area at an initial moving speed.

[0056] In some examples, the method further includes:

[0057] The water pressure of the deionized water jet sprayed from the high-pressure cleaning nozzle onto the target area is maintained within the set water pressure range.

[0058] It should be noted that, Figure 8 The steps in the technical solution shown, along with corresponding examples, can be derived from... Figure 3 The corresponding components in the device 3 shown are implemented, and the embodiments of the present invention will not be described in detail.

[0059] Understandably, in this embodiment, Figure 8 The method for cleaning and polishing pads shown can be implemented either in hardware or as a software functional module.

[0060] If implemented as a software functional module and not sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the method described in this embodiment. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0061] Therefore, this embodiment provides a computer storage medium storing a program for cleaning a polishing pad. When the program for cleaning the polishing pad is executed by at least one processor, it implements the method steps for cleaning the polishing pad described in the above technical solution.

[0062] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0063] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of cleaning a polishing pad, characterized by, The method includes: When the high-pressure cleaning nozzle sprays deionized water at a set angle onto the target area of ​​the polishing pad, a pressure sensor located at a set position above the polishing pad senses the pressure value of the reflected water flow; wherein, the reflected water flow is formed by the deionized water flow being reflected by the target area; If the pressure value of the reflected water flow is greater than the set first pressure threshold, the duration for which the high-pressure cleaning nozzle sprays deionized water flow onto the target area is extended. When the pressure value of the reflected water flow is less than a set second pressure threshold, the high-pressure cleaning nozzle is moved to spray deionized water into the next area of ​​the target area; wherein the second pressure threshold is less than the first pressure threshold. The method of extending the duration of the high-pressure cleaning nozzle spraying deionized water into the target area includes: Reduce the moving speed of the high-pressure cleaning nozzle in the space above the target area.

2. The method of claim 1, wherein, The method further includes the following steps when the pressure value of the reflected water flow is greater than a set first pressure threshold: Increase the water pressure of the deionized water jet sprayed from the high-pressure cleaning nozzle onto the target area.

3. The method of claim 1, wherein, Since the pressure value of the reflected water flow is less than the first pressure threshold and greater than the second pressure threshold, the method further includes: The high-pressure cleaning nozzle moves within the space above the target area at an initial moving speed.

4. The method of claim 3, wherein, The method further includes: The water pressure of the deionized water jet sprayed from the high-pressure cleaning nozzle onto the target area is maintained within the set water pressure range.

5. An apparatus for cleaning a polishing pad, comprising: The device includes: High-pressure cleaning arm; A high-pressure cleaning nozzle is provided at one end of the high-pressure cleaning arm. The spray direction of the high-pressure cleaning nozzle can be adjusted to spray deionized water into the target area on the polishing pad at a set angle. A moving motor located at the other end of the high-pressure cleaning arm controls the movement of the high-pressure cleaning arm to drive the movement of the high-pressure cleaning nozzle. A pressure sensor is positioned at a predetermined distance from the high-pressure cleaning nozzle and above the polishing pad to sense the pressure value of the reflected water flow; wherein the reflected water flow is formed by the deionized water flow reflecting off the target area; The controller is used to extend the duration of the high-pressure cleaning nozzle spraying deionized water into the target area by controlling the working state of the moving motor when the pressure value of the reflected water flow is greater than a set first pressure threshold. Corresponding to the fact that the pressure value of the reflected water flow is less than a set second pressure threshold, the high-pressure cleaning nozzle is moved by controlling the working state of the moving motor to spray deionized water into the next area of ​​the target area; wherein, the second pressure threshold is less than the first pressure threshold; and The movement speed of the high-pressure cleaning nozzle in the space above the target area is reduced by decreasing the power of the moving motor.

6. The apparatus of claim 5, wherein, The device further includes a deionized water supply section for providing deionized water at a set pressure to the high-pressure cleaning nozzle; The controller is further configured to increase the water pressure of the deionized water supplied by the deionized water supply section to the high-pressure cleaning nozzle when the pressure value of the reflected water flow is greater than a set first pressure threshold, so as to increase the water pressure of the deionized water flow sprayed by the high-pressure cleaning nozzle onto the target area.

7. The apparatus of claim 5, wherein, The controller is further configured to, in response to a pressure value of the reflected water flow being less than the first pressure threshold and greater than the second pressure threshold, change the power of the moving motor to cause the high-pressure cleaning nozzle to move within the space above the target area at an initial moving speed.

8. The apparatus of claim 7, wherein, The device further includes a deionized water supply section for providing deionized water at a set pressure to the high-pressure cleaning nozzle; The controller is also configured to set the water pressure of the deionized water supplied by the deionized water supply section to the high-pressure cleaning nozzle according to a set water pressure range, so as to maintain the water pressure of the deionized water jet sprayed by the high-pressure cleaning nozzle to the target area within the set water pressure range.

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