A wafer cleaning device for controlling the posture of cleaning brushes

Abstract

This invention discloses a wafer cleaning device for controlling the posture of cleaning brushes, comprising: a wafer rotation assembly for supporting and driving the wafer to rotate; two cleaning brushes disposed on both sides of the wafer and rolling around their own axes to clean the wafer surface; a cleaning brush motion mechanism for driving the two cleaning brushes to move towards each other and clamp the wafer at a certain angle for cleaning; and a controller for controlling the cleaning brush motion mechanism to adjust the angle between the two cleaning brushes, such that the clamping force of the end of the cleaning brush in the same direction as the wafer rotation on the wafer is greater than the clamping force of the end of the cleaning brush in the opposite direction to the wafer rotation on the wafer.

Description

Technical Field

[0001] This invention belongs to the field of post-chemical mechanical polishing cleaning technology, and particularly relates to a wafer cleaning device for controlling the posture of the cleaning brush. Background Technology

[0002] Chemical Mechanical Polishing (CMP) is an ultra-precision surface finishing process that achieves global planarization. However, the large amounts of chemical reagents and abrasives used in CMP leave significant residues of abrasive particles and byproducts on the wafer surface after polishing. These contaminants can negatively impact subsequent processes and potentially lead to wafer yield losses. Therefore, multiple surface cleaning processes are required during wafer manufacturing to remove contaminants such as metal ions, atoms, organic matter, and particles adhering to the wafer surface.

[0003] Patent CN102768974B discloses a wafer cleaning equipment. The wafer cleaning equipment includes: a rack; a wafer cleaning device mounted on the rack; a wafer brushing device mounted on the rack and located downstream of the wafer cleaning device; a wafer drying device mounted on the rack and located downstream of the wafer brushing device; and a robotic arm movably mounted on the rack for vertically clamping and transporting wafers.

[0004] However, existing technologies have a problem where the brush holding the wafer during wafer washing affects the wafer rotation speed, causing the wafer rotation speed to slow down and ultimately affecting the cleaning effect. Summary of the Invention

[0005] This invention provides a wafer cleaning apparatus for controlling the posture of a cleaning brush, aiming to at least solve one of the technical problems existing in the prior art.

[0006] This invention provides a wafer cleaning apparatus for controlling the posture of a cleaning brush, comprising:

[0007] Wafer rotation assembly, used to support and drive the wafer to rotate;

[0008] Two cleaning brushes are positioned on both sides of the wafer and roll around their own axis to clean the wafer surface.

[0009] The cleaning brush motion mechanism is used to drive the two cleaning brushes to move towards each other and clamp the wafer at a certain angle for cleaning.

[0010] The controller is used to control the cleaning brush motion mechanism to adjust the included angle between the two cleaning brushes, so that the clamping force of the end of the cleaning brush that is in the same direction as the wafer rotation on the wafer is greater than the clamping force of the end of the cleaning brush that is in the opposite direction to the wafer rotation on the wafer.

[0011] In one embodiment, the first spacing between the two cleaning brushes at the end of the wafer that are in the same direction of rotation is less than the second spacing between the two cleaning brushes at the end of the wafer that are in the opposite direction of rotation.

[0012] In one embodiment, the difference between the second spacing and the first spacing is 0.1 to 0.5 mm.

[0013] In one embodiment, the wafer rotation assembly includes a rotation speed sensor for detecting the wafer rotation speed;

[0014] The controller acquires the wafer rotation speed detected by the rotation speed sensor and controls the cleaning brush motion mechanism to adjust the included angle when the wafer rotation speed is not within the normal range.

[0015] In one embodiment, the controller includes:

[0016] The first control module is used to increase the included angle between the two cleaning brushes to increase the frictional torque of the cleaning brushes on the wafer when the wafer rotation speed is too low.

[0017] The second control module is used to reduce the angle between the two cleaning brushes to reduce the frictional torque of the cleaning brushes on the wafer when the wafer rotation speed is too high.

[0018] In one embodiment, the normal range of the wafer rotation speed is 40 rpm to 60 rpm.

[0019] In one embodiment, the wafer rotation assembly includes an active roller and a driven roller, and the driven roller is provided with the speed sensor.

[0020] The beneficial effects of the embodiments of the present invention include: increasing the rotational driving force of the cleaning brush on the wafer, thereby improving the cleaning effect. Attached Figure Description

[0021] The advantages of the present invention will become clearer and easier to understand through the detailed description taken in conjunction with the following accompanying drawings, but these drawings are merely illustrative and do not limit the scope of protection of the present invention, wherein:

[0022] Figure 1 A schematic diagram of a wafer cleaning apparatus provided in one embodiment of the present invention;

[0023] Figure 2 A schematic flowchart of a wafer cleaning operation method provided in one embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of a cleaning process provided for one embodiment of the present invention. Detailed Implementation

[0025] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein. It should be understood that, unless specifically stated otherwise, for ease of understanding, the following description of specific embodiments of the present invention is based on the premise that the relevant equipment, devices, components, etc., are in their original static state and are not given external control signals or driving forces.

[0026] Furthermore, it should be noted that the terms used in this application to indicate orientation, such as front, back, up, down, left, right, top, bottom, front, back, horizontal, and vertical, are merely for ease of explanation and to aid in the understanding of relative position or direction, and are not intended to limit the orientation of any device or structure.

[0027] To illustrate the technical solution described in this invention, specific embodiments are described below.

[0028] In this application, chemical mechanical polishing is also referred to as chemical mechanical planarization. The substrate is also referred to as a wafer, with the same meaning and practical function.

[0029] Figure 1 This is a schematic diagram of the structure of a wafer cleaning device 1 for controlling the posture of the cleaning brush provided in an embodiment of the present invention. The wafer cleaning device 1 includes a base 10, a wafer rotation assembly 20, two cleaning brushes 30, a cleaning brush motion mechanism, and a controller (not shown).

[0030] like Figure 1 As shown, the wafer rotation assembly 20 is disposed on the upper part of the base 10, and the wafer W to be cleaned is supported by the wafer rotation assembly 20 and rotates around the axis of the wafer W.

[0031] The wafer rotation assembly 20 includes a fixed base, a pair of driving rollers and a driven roller. The driving and driven rollers are equipped with slots for supporting the wafer, and these slots are arranged around the outer periphery of the rollers. The driving and driven rollers are located on the fixed base, and the slots are in the same plane. The driven roller is located in the center of the fixed base, and the driving roller is symmetrically arranged on both sides of the driven roller. The pair of driving and driven rollers are arranged along the outer edge contour of the wafer. The wafer W placed in the wafer rotation assembly 20 is limited by the slots, and the outer edge of the wafer is tangent to the bottom surface of the slots. The driving rollers are equipped with drive motors, which drive the driving rollers to rotate. The friction between the outer edge of the wafer and the rollers causes the wafer to rotate around its axis.

[0032] In one embodiment, a speed sensor for detecting wafer rotation speed is provided on the driven roller. The speed sensor can be implemented by a Hall sensor or a photoelectric switch sensor.

[0033] like Figure 1 As shown, the cleaning brush 30 has a cylindrical structure and is made of a material with good water absorption, such as polyvinyl alcohol. The two cleaning brushes 30 are the first cleaning brush and the second cleaning brush, respectively, and are disposed on both sides of the wafer W to be cleaned. They can roll around their own axis to contact the surface of the wafer W to be cleaned.

[0034] like Figure 1 As shown, the cleaning brush motion mechanism is used to drive the two cleaning brushes to move towards each other and clamp the wafer at a certain angle for cleaning. The cleaning brush motion mechanism includes a cleaning brush support assembly 40 and a cleaning brush moving assembly 50.

[0035] The cleaning brush support assembly 40 is used to support two cleaning brushes 30 located on both sides of the wafer W to be cleaned.

[0036] A cleaning brush moving assembly 50 is connected to a cleaning brush support assembly 40 to drive the cleaning brush support assembly 40 and the cleaning brush 30 thereon to move as a whole. The cleaning brush moving assembly 50 includes a guide rail, a lead screw, and a driving component. The guide rail and lead screw are respectively connected to the cleaning brush support assembly 40 so that the cleaning brush support assembly 40 moves along the guide rail under the drive of the lead screw. The driving component is located at the end of the lead screw and drives the lead screw to move, thereby moving the cleaning brush support assembly 40 and the cleaning brush 30 as a whole, so that both ends of the cleaning brush 30 simultaneously contact or move away from the wafer. Furthermore, lead screws are respectively provided at both ends of the cleaning brush, thereby allowing for independent adjustment of the movement distance at each end of the cleaning brush.

[0037] One embodiment of the present invention provides a controller for controlling the cleaning brush motion mechanism to adjust the included angle between the two cleaning brushes 30, such that the clamping force of the end of the cleaning brush 30 in the same direction as the wafer rotation is greater than the clamping force of the end of the cleaning brush 30 in the opposite direction to the wafer rotation. In other words, referring to... Figure 1 , Figure 1 The clamping force of the right end of the cleaning brush 30 on the wafer is greater than that of the left end, thereby increasing the rotational driving force of the cleaning brush on the wafer.

[0038] In this embodiment, the two cleaning brushes 30 form an angle between them. This angle means that during the process of using the cleaning brushes 30 to clean the wafer, the two cleaning brushes 30 are not completely parallel, but form a very small angle.

[0039] See Figure 1 As the wafer rotates, the circumferential velocity of the right-hand wafer is downward, while that of the left-hand wafer is upward. The two cleaning brushes 30 rotate in the direction that provides downward friction to the wafer. Figure 1 As shown by the middle arrow, the linear velocity of the cleaning brush 30 at the contact point with the wafer is downward, regardless of whether it is on the right or left side. Therefore, the right end of the cleaning brush 30 rotates in the same direction as the wafer, providing a unidirectional rotational driving force to the wafer; the left end of the cleaning brush 30 rotates in the opposite direction to the wafer, and the relative velocity between the left end of the cleaning brush 30 and the wafer is greatest at the contact point, resulting in the best cleaning effect.

[0040] In one embodiment, the first spacing between the two cleaning brushes at the end where the cleaning brush is in the same direction as the wafer rotation is less than the second spacing between the two cleaning brushes at the end where the cleaning brush is in the opposite direction to the wafer rotation. See also Figure 1 The first spacing between the right ends of the two cleaning brushes is smaller than the second spacing between the left ends.

[0041] The difference between the second spacing and the first spacing is 0.1 to 0.5 mm, preferably 0.1 to 0.2 mm.

[0042] This embodiment limits the difference between the two spacings, which ensures that the cleaning brush provides the wafer with a rotational driving force in the same direction, while also ensuring that the spacing at the opposite end, where the relative speed is the greatest and the cleaning effect is the best, is not too large, thereby guaranteeing the cleaning effect.

[0043] In this embodiment of the invention, the cleaning brush 30 is positioned at the end that is in the same direction as the wafer rotation. Figure 1 The right-hand end, where the wafer is clamped more tightly (i.e., with a smaller gap), provides a rotational driving force for the wafer during cleaning. This increases the frictional torque to enhance the driving force when the wafer rotation speed is low. The cleaning brush is located at the end opposite to the wafer's rotation direction. Figure 1 The left-hand end, where the wafer is held more loosely (i.e., with a larger gap), applies resistance to the wafer during cleaning. Therefore, the frictional torque is reduced to increase resistance when the wafer rotation speed is high. The clamping end of the cleaning brush rotates in the same direction as the wafer, and the overall rotation of the wafer is driven by frictional torque.

[0044] In addition, the wafer should maintain a stable rotation speed during cleaning. However, currently, the angle between the two cleaning brushes 30 is usually set to a fixed value during the cleaning process. When the clamping distance of the cleaning brushes 30 reaches a certain value, it will cause the wafer to overspeed or slow down, making it impossible to maintain a constant wafer rotation speed. This will affect the consistency of chemical spraying and the reaction time of chemicals on the wafer surface, ultimately affecting the cleaning effect.

[0045] To address this issue, another embodiment of the present invention provides a controller for acquiring the wafer rotation speed detected by a rotation speed sensor and adjusting the angle between the two cleaning brushes when the wafer rotation speed is outside the normal range. The normal range for the wafer rotation speed is 40 rpm to 60 rpm, preferably 50 rpm ± 10%.

[0046] In one embodiment of the present invention, the controller includes:

[0047] The first control module is used to increase the included angle between the two cleaning brushes to increase the frictional torque of the cleaning brushes on the wafer when the wafer rotation speed is too low.

[0048] The second control module is used to reduce the angle between the two cleaning brushes to reduce the frictional torque of the cleaning brushes on the wafer when the wafer rotation speed is too high.

[0049] Furthermore, the first control module and the second control module can move independently or in combination to increase or decrease the included angle; it is not necessarily the case that one controls the increase while the other controls the decrease.

[0050] Due to factors such as wear and tear on the cleaning brush, the cleaning environment, and equipment usage, wafers may experience speed overruns or speed drops during cleaning, leading to inconsistent rotational speeds. Therefore, addressing the issue of stable wafer rotational speed is crucial. This invention achieves stable rotational speed during wafer brushing, improving the consistency of cleaning fluid spraying and the reaction time of the cleaning fluid on the wafer surface, thus enhancing the cleaning effect.

[0051] like Figure 2 As shown, combined with Figure 1 Briefly describe the wafer cleaning process.

[0052] The first step is for the robotic arm to place the wafer W to be cleaned onto the wafer rotation assembly 20. At this time, a certain distance is reserved between the cleaning brush 30 and the side of the wafer W to provide working space for the robotic arm.

[0053] In the second step, the wafer rotation assembly 20 drives the wafer W to rotate around its axis, and the fluid jetting device (not shown) sprays cleaning fluid, such as acidic or alkaline cleaning fluid, toward the rotating wafer W.

[0054] Third, the two cleaning brushes 30 roll around their axes and move toward the wafer W, so that the cleaning brushes 30 contact the surface of the wafer W, and the first and second cleaning brushes are not completely parallel, but have a certain angle between them. For example, the first end of the first cleaning brush and the first end of the second cleaning brush press against the wafer, and the second end of the first cleaning brush and the second end of the second cleaning brush slightly contact the wafer. In other words, the distance between the first end of the first cleaning brush and the first end of the second cleaning brush is smaller than the distance between the second end of the first cleaning brush and the second end of the second cleaning brush.

[0055] The fourth step is to use a 30-rolling cleaning brush to clean the surface of the wafer W, removing contaminants from the wafer surface and achieving surface cleaning of the wafer.

[0056] Fifth step: After the wafer is cleaned, the cleaning brush 30 moves toward the outside of the wafer W and separates from the surface of the wafer W.

[0057] In the sixth step, the fluid jetting device (not shown) continues to spray cleaning fluid toward the rotating wafer W. After rinsing for a period of time, the wafer rotation is stopped, and the robot arm transfers the cleaned wafer W to the next process.

[0058] As can be seen from the wafer cleaning operation method, the position of the cleaning brush 30 needs to be moved at the beginning and end of the wafer cleaning process. Since the distance between the cleaning brush 30 and the wafer W determines their contact state, and this contact state is directly related to the effectiveness of the wafer surface cleaning, it is necessary to precisely control the moving distance and angle of the two cleaning brushes 30.

[0059] Furthermore, as the cleaning brush wears down with repeated use, the friction between the brush and the wafer decreases for the same clamping stroke, resulting in poorer cleaning performance. Therefore, it is necessary to control the clamping stroke of the cleaning brush.

[0060] In one embodiment of the present invention, the controller further includes:

[0061] The storage module is used to record the cumulative number of cleaning brush runs, where the cumulative number of cleaning brush runs is the cumulative running time of the cleaning brush or the cumulative number of wafers cleaned by the cleaning brush.

[0062] The pre-control module is used to adjust the cleaning brush clamping stroke setting when the cumulative number of cleaning brush cycles reaches a preset amount. The cleaning brush clamping stroke setting is a preset distance that the cleaning brush moves from the starting position to the wafer clamping position. For example, the cleaning brush clamping stroke setting is adjusted every 100 wafers processed by the cleaning brush to reduce the distance between the two cleaning brushes while maintaining a stable frictional force on the wafer.

[0063] The controller moves the cleaning brush to the wafer clamping position according to the set value of the cleaning brush clamping stroke to perform the wafer cleaning process.

[0064] In this embodiment, the initial distance the cleaning brush moves to the wafer is adjusted based on the operating status of the cleaning brush, i.e., the cleaning brush clamping stroke setting value. Figure 2 The distance the cleaning brush moves in the third step shown is adjusted to maintain stable friction during brushing, ensuring that the cleaning effect does not deteriorate over time.

[0065] In this application, the distance of the clamping movement at both ends of each cleaning brush is controlled by the cleaning brush motion mechanism. For example, the initial setting of the cleaning brush clamping stroke is 10mm. When the cleaning brush cleans 100 wafers, due to the wear of the cleaning brush and other reasons, in order to maintain the consistent clamping force on the wafers, the setting is adjusted from 10mm to 10.1mm.

[0066] Preferably, in one embodiment, the preset amount can be determined by the type of consumables for the cleaning brush, and the preset amount varies depending on the type of consumables for different cleaning brushes.

[0067] In one embodiment, the wafer rotation speed of the cleaning brush is recorded at different operating levels, and when the wafer rotation speed reaches a critical value, the operating level of the cleaning brush at this time is set to a preset level.

[0068] For ease of understanding, such as Figure 3 As shown, the wafer cleaning solution provided by the embodiments of the present invention is illustrated using a specific application scenario as an example.

[0069] 1) After starting, determine whether the cumulative running volume of the cleaning brush has reached the preset amount;

[0070] 2) If so, adjust the cleaning brush clamping stroke setting, for example, by reducing the cleaning brush spacing;

[0071] 3) The wafer starts rotating, and the cleaning brush is controlled to rotate and clamp the wafer according to the adjusted stroke setting value;

[0072] 4) Determine if the washing is finished;

[0073] 5) If the washing end time has not been reached, check whether the wafer rotation speed is within the normal range;

[0074] 6) If yes, continue cleaning and continuously monitor the wafer rotation speed; if not, finely adjust the angle between the two cleaning brushes.

[0075] 7) If the cleaning end time is reached, drive the cleaning brush to open, and stop rotating after the wafer is rinsed to complete the cleaning.

[0076] In summary, the embodiments of the present invention can finely adjust the cleaning brush angle according to the changes in wafer rotation speed to maintain stable wafer rotation speed, and can actively adjust the clamping stroke according to the running time of consumables, thereby maintaining a good cleaning effect and improving the service life of the cleaning brush.

[0077] The accompanying drawings in this specification are schematic diagrams used to illustrate the concept of the invention and to schematically show the shapes of the various parts and their interrelationships. It should be understood that, in order to clearly show the structure of the various components of the embodiments of the invention, the drawings are not drawn to the same scale, and the same reference numerals are used to indicate the same parts in the drawings.

[0078] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0079] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A wafer cleaning apparatus for controlling the posture of a cleaning brush, characterized in that, include: Wafer rotation assembly, used to support and drive the wafer to rotate; Two cleaning brushes are positioned on both sides of the wafer and roll around their own axis to clean the wafer surface. The cleaning brush motion mechanism is used to drive the two cleaning brushes to move towards each other and clamp the wafer at a certain angle for cleaning. The cleaning brush motion mechanism can adjust the moving distance of the two ends of the cleaning brushes respectively. A controller is configured to acquire the wafer rotation speed detected by a speed sensor and adjust the angle between the two cleaning brushes when the wafer rotation speed is outside the normal range, such that the clamping force of the end of the cleaning brush in the same direction as the wafer rotation is greater than the clamping force of the end of the cleaning brush in the opposite direction of the wafer rotation, and a first distance between the two cleaning brushes at the end in the same direction as the wafer rotation is less than a second distance between the two cleaning brushes at the end in the opposite direction of the wafer rotation, wherein the difference between the second distance and the first distance is 0.1–0.5 mm; the controller includes: The first control module is used to increase the included angle between the two cleaning brushes to increase the frictional torque of the cleaning brushes on the wafer when the wafer rotation speed is too low. The second control module is used to reduce the angle between the two cleaning brushes to reduce the frictional torque of the cleaning brushes on the wafer when the wafer rotation speed is too high.

2. The wafer cleaning apparatus as described in claim 1, characterized in that, The normal range of the wafer rotation speed is 40 rpm to 60 rpm.

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