Wafer polishing method, polishing unit, and processing apparatus
By dividing the wafer into multiple partitions, independently controlling the polishing pressure, and adjusting the polishing fluid flow function, the problem that existing equipment cannot meet the processing of diverse wafer surface shapes is solved, and precise processing and consistency of wafers with specific surface shapes are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HWATSING TECHNOLOGY CO LTD
- Filing Date
- 2025-04-15
- Publication Date
- 2026-07-03
AI Technical Summary
Existing chemical mechanical polishing equipment cannot meet the processing requirements of different wafer surface types. Especially with the continuous improvement of integrated circuit process nodes, the wafer surface exhibits non-uniformity, which makes it impossible to meet processing requirements.
By dividing the wafer into multiple partitions, independently controlling the polishing pressure, and adjusting the polishing slurry flow rate function according to the initial and target thickness functions, precise removal of material from the wafer surface can be achieved. The supply of polishing slurry is controlled by the polishing slurry flow rate function, and surface correction is achieved by combining a detection device and a controller.
It enables precise machining of wafers with specific surface shapes, improves machining accuracy and consistency, and meets the machining requirements of different wafer surface shapes.
Smart Images
Figure CN120287204B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical mechanical polishing technology, and more specifically, relates to a wafer polishing method, polishing unit, and processing equipment. Background Technology
[0002] Chemical mechanical polishing (CMP) equipment is currently the only equipment that can achieve global planarization of the wafer surface. As the process nodes of integrated circuits continue to improve, the number of CMP steps in the entire manufacturing process is increasing, and the polishing requirements for different wafer surface types are also diverse. Existing processing methods cannot meet the processing needs of wafers with specific surface types. Summary of the Invention
[0003] In view of this, the present invention provides a wafer polishing method, polishing unit, and polishing equipment, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.
[0004] To achieve the aforementioned objective, a first aspect of the present invention provides a wafer polishing method, comprising:
[0005] The wafer dicing step involves a polishing head air film comprising N radially divided partitions with independently controllable polishing pressure. The wafer is diced in a manner that corresponds one-to-one with the partitions of the polishing head air film, where N≥1.
[0006] The thickness function determination step obtains the initial surface shape and target surface shape of the nth partition on the wafer surface. The initial surface shape and target surface shape are represented by the initial thickness function f(θ) and target thickness function g(θ) after wafer partitioning, where θ is the wafer rotation angle, and N≥n≥1;
[0007] The step of determining the polishing slurry flow rate function is to determine the material removal rate function of the nth partition on the wafer surface. The material removal rate function is a composite function of the polishing slurry flow rate function, which is a periodic function F(θ) with a period of 2π about the wafer rotation angle θ.
[0008] The calibration step involves supplying polishing slurry to the wafer according to the polishing slurry flow rate function, and then calibrating the polishing slurry flow rate function based on the test polishing results, the initial thickness function, and the target thickness function.
[0009] In the polishing step, polishing slurry is supplied according to the corrected polishing slurry flow function to continue polishing the wafer.
[0010] As described above in the wafer polishing method, optionally, the material removal rate function is a function RR(θ) = kF(θ)VP determined according to the Princeton equation, where k is a constant coefficient, P is the polishing pressure, and V is the relative velocity.
[0011] As described above in the wafer polishing method, optionally, the function for determining the material removal rate of the nth partition on the wafer surface includes: controlling the polishing pressure to be P0 and the polishing head rotation speed to be ω. h The polishing disc rotates at a speed of ω. p The polishing slurry flow rate is F0, and the polishing time for the wafer is T. t The amount of material removed from the nth partition on the wafer surface is measured, and the constant coefficient k is calculated based on the material removal rate function.
[0012] The wafer polishing method described above may optionally further include: expressing the polishing fluid flow rate function as a function of the wafer rotation time t. A and These are the amplitude parameter and the phase parameter, respectively.
[0013] As described above in the wafer polishing method, optionally, the step of supplying polishing fluid to test-polish the wafer according to the polishing fluid flow rate function includes:
[0014] Assign initial values A = A0 to the amplitude and phase parameters.
[0015] Control the nth partition Z n The polishing pressure is The polishing head rotation speed is ω h The polishing disc rotates at a speed of ω. p And according to the polishing fluid flow function Supply polishing fluid.
[0016] As described above in the wafer polishing method, optionally, the step of correcting the polishing fluid flow rate function based on the trial polishing results, the initial thickness function, and the target thickness function includes:
[0017] Measure the amount of material removed after the trial grinding of the nth zone, and obtain the location of the trial grinding feature point and the amount of material removed during the trial grinding.
[0018] The location of the target feature points and the amount of target removal are obtained based on the initial objective function and the target thickness function;
[0019] The amplitude parameter is corrected based on the location of the feature point after trial grinding and the location of the target feature point; the phase parameter is corrected based on the removal amount after trial grinding and the target removal amount; and / or,
[0020] The amplitude parameter is corrected based on the location of the feature point after the trial grinding and the location of the target feature point. The amplitude parameter is also corrected based on the amount removed during the trial grinding, the corrected phase parameter, and the trial grinding time.
[0021] In the wafer polishing method described above, optionally, the feature point is the point of minimum material removal and / or the point of maximum material removal.
[0022] The wafer polishing method described above may optionally include: detecting the angle of the wafer to rotate the wafer to a specific angle before the first polishing step.
[0023] The wafer polishing method described above may optionally include: detecting the wafer surface profile after the polishing step, and repeating the correction and polishing steps if it does not conform to the target thickness function.
[0024] A second aspect of the present invention provides a wafer polishing unit, comprising: a polishing head, a polishing disk, a detection device, a polishing slurry supply device, and a flow controller. The detection device includes a first detection module for measuring wafer thickness, and the flow controller is used to control the polishing slurry supply device to supply polishing slurry according to a polishing slurry flow rate function as described in the wafer polishing method of the first aspect.
[0025] The wafer polishing unit described above may optionally include a wafer interaction device, which is used to carry the wafer and interact with the polishing head.
[0026] The detection device further includes a second detection module, which is used to detect the angle of the wafer carried on the wafer interaction device;
[0027] The wafer interaction device includes a rotating component, and the rotating component and a second detection device are used to rotate the wafer to a predetermined angle.
[0028] A third aspect of the present invention provides a wafer processing apparatus, including a controller and a wafer polishing unit as described in the second aspect, wherein the controller is electrically connected to the wafer polishing unit and is used to control the wafer polishing unit to perform the wafer polishing method as described in the first aspect.
[0029] Compared with the prior art, the wafer polishing method of the present invention can realize wafer processing with specific surface shapes. Attached Figure Description
[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0031] Figure 1 This is a schematic diagram of a wafer polishing unit in the prior art.
[0032] Figure 2 This is a schematic flowchart of an embodiment of the wafer polishing method of the present invention.
[0033] Figure 3This is a schematic flowchart of Embodiment 2 of the wafer polishing method of the present invention.
[0034] Figure 4 This is a schematic flowchart of Embodiment 3 of the wafer polishing method of the present invention.
[0035] Figure 5 This is a schematic diagram of the wafer polishing unit of the present invention.
[0036] Figure 6 This is a schematic diagram of the wafer processing equipment of the present invention.
[0037] Reference numerals: Polishing head 10; Polishing fluid supply device 20; Polishing disc 30; Dressing device 40; Detection device 50; First detection module 51; Second detection module 52; Flow controller 60; Wafer interaction device 70; Wafer polishing unit 100. Detailed Implementation
[0038] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.
[0039] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0040] In addition, in the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.
[0041] Figure 1This is a schematic diagram of a wafer polishing unit in the prior art. As shown in the figure, the lower surface of the polishing head 10 is provided with an air film and a retaining ring surrounding the air film. The polishing head can adsorb the wafer to be polished through the air film and confine the wafer inside the retaining ring. The polishing slurry supply device 20 distributes the polishing slurry onto the surface of the polishing pad covering the polishing disk 30. The dressing device 40 includes a dressing arm and a dressing head. The dressing arm drives the rotating dressing head to swing and dress the surface of the polishing pad to a state suitable for polishing. During the polishing operation, the polishing head presses the surface of the wafer to be polished against the surface of the rotating polishing pad and rotates and moves. The polishing slurry is distributed between the polishing pad and the wafer. Under the action of chemical machinery, the material on the wafer surface is removed, achieving the purpose of global and local planarization.
[0042] However, with the continuous advancement of process nodes, various new materials and methods for deposition on wafer surfaces are emerging one after another, requiring wafer surfaces to exhibit non-uniformity, that is, requiring wafers to be processed with specific surface shapes. Existing equipment and methods can no longer meet the processing requirements.
[0043] This invention provides a wafer polishing method that achieves different material removal amounts along the circumference of the wafer by controlling the flow rate of the polishing slurry, thereby enabling the processing of specific wafer surface shapes.
[0044] Example 1
[0045] Figure 2 This is a schematic flowchart of an embodiment of the wafer polishing method of the present invention. Figure 2 As shown, the wafer polishing method includes the following steps:
[0046] S101. Wafer dicing step. In the wafer dicing step, the wafer surface is divided radially into N partitions in a manner that corresponds one-to-one with the gas film of the polishing head, where N is a positive integer.
[0047] The polishing head's gas film comprises N radially divided zones, with the central zone being circular and the others being annular. Each zone is connected to an independent gas flow path, allowing independent control of the pressure within the zone's gas film. This enables control of the polishing pressure applied to the wafer according to the gas film zones. By dividing the wafer into zones corresponding one-to-one with the polishing head's gas film zones, the polishing pressure in different radial regions of the wafer can be determined based on these zones. The method of dividing the polishing head can refer to other existing technologies and is not limited here. The polishing pressure of the nth zone from the inside out is denoted as...
[0048] S102. Determine the thickness function step. In the thickness function determination step, the initial surface shape and target surface shape of the nth partition on the wafer surface are obtained. The initial surface shape and target surface shape are represented by the initial thickness function f(θ) and target thickness function g(θ) after wafer partitioning, where θ is the wafer rotation angle.
[0049] The surface profile of a wafer can be represented by a wafer thickness function. The initial thickness function represents the thickness distribution of the wafer to be polished, i.e., the initial surface profile. The wafer thickness can be obtained using existing thickness measurement methods, such as optical measurement and acoustic measurement, which are not limited here. Typically, wafers in the same batch have the same initial surface profile, so the same initial thickness function can be used for wafers in the same batch.
[0050] The target thickness function represents the thickness distribution of the wafer after polishing, which is the desired surface shape to be processed. It is determined by the wafer processing requirements and can be generated directly according to the processing requirements or obtained by measuring the thickness of the finished product.
[0051] By defining an initial angle of 0 on the wafer, any point (d, θ) on the wafer surface can be determined using the distance d from the wafer center and the rotation angle θ relative to the initial angle. In other words, a thickness function f(d, θ) can be established with the wafer center as the origin and the radial direction pointing to the initial angle as the polar coordinate axis to represent the thickness at any position on the wafer surface.
[0052] As an example, after wafer partitioning, the distance between a point in the nth partition and the wafer center is considered a constant value Z. n The points within the nth partition can be represented by (Z). n ,θ) represents Z n Preferably, it is the average of the inner and outer diameters of the nth partition. Thus, the thickness function f(d,θ) is rewritten as the initial thickness function f(θ) and the target thickness function g(θ). S103. Determining the polishing slurry flow rate function. In this step, the material removal rate function and the polishing slurry flow rate function of the nth partition on the wafer surface are simultaneously determined. The material removal rate function is a composite function of the polishing slurry flow rate function, and the polishing slurry flow rate function is a periodic function F(θ) with a period of 2π about the wafer rotation angle θ.
[0053] Material Removal Rate (MRR) is typically expressed as volume divided by time, describing the volume of material removed per unit time. In chemical mechanical polishing (CMP), various models describe MRR to characterize the relationship between multiple factors influencing MRR and the material removal rate. This invention selects a model that incorporates the polishing slurry flow rate and can be expressed as a function, rewriting the function as a composite function of the polishing slurry flow rate: RR(θ) = α·F(θ), where α is a coefficient characterizing other factors affecting the material removal rate.
[0054] S104. First polishing step. In the first polishing step, polishing fluid is supplied to the polishing pad according to the polishing fluid flow rate function determined in S104, while other factors affecting the material removal rate are kept constant or fixed to ensure the solvability of the material removal rate function, and the wafer is polished for a predetermined time.
[0055] S105. Correction Step. In the correction step, the polishing slurry flow rate function F(θ) is corrected based on the wafer surface shape after polishing in S104, the initial thickness function f(θ), and the target thickness function g(θ).
[0056] As an example, the polishing fluid flow function F(θ) includes at least one parameter, and the polishing fluid flow function F(θ) is corrected by correcting the value of the parameter.
[0057] S106. Secondary polishing step. In the secondary polishing step, polishing fluid is supplied to the polishing pad according to the corrected polishing fluid flow function, while controlling other factors affecting the material removal rate in the same way as in S104, and the wafer is polished for a predetermined time.
[0058] Through steps S101-S106, the wafer polishing method of the present invention can process wafers with specific surface shapes, especially wafers with specific thickness distribution in the circumferential direction.
[0059] Optionally, before step S101, a step S100, a wafer angle detection and rotation step, is included. In the wafer angle detection and rotation step, the wafer orientation is detected to determine the initial angle of the wafer, so that the wafer before the first polishing step is rotated to a specific angle, preferably such that the initial phase difference between the initial thickness function, the target thickness function, and the polishing fluid flow rate function is 0.
[0060] As an example, the wafer edge is notched. Before polishing begins, the notch direction is adjusted to a fixed orientation, so that the polishing slurry flow function can be described as having a fixed initial phase relative to the initial thickness function and the target thickness function. Preferably, the notch direction is adjusted so that the wafer is directly opposite the polishing slurry supply position when polishing begins, thus the initial phase of the polishing slurry flow function is 0, simplifying control during the polishing process. Furthermore, when processing wafers in the same batch to a consistent specific target surface shape, all wafers have the same initial angle.
[0061] Optionally, after step S106, a wafer surface profile inspection step is also included. The wafer surface profile after the secondary polishing in step S106 is inspected. If the measured surface profile does not conform to the target thickness function, step S105 is repeated to recalibrate the polishing slurry flow rate function, and step S106 is followed by supplying polishing slurry according to the recalibrated polishing flow rate function to continue polishing the wafer.
[0062] Example 2
[0063] Figure 3 This is a schematic flowchart of another embodiment of the wafer polishing method of the present invention. The wafer polishing method of the present invention will be described in detail below with reference to Embodiment 2. Figure 3 As shown, the wafer polishing method includes the following steps:
[0064] S200. Detect wafer notches, with the wafer center as the origin and the radius pointing from the origin to the notch as the polar coordinate axis; rotate the wafer to align the notch direction with the polishing slurry supply device 20.
[0065] S201. Divide the wafer surface into N equal-width partitions along the radial direction, in a manner that corresponds one-to-one with the gas film of the polishing head, where N is a positive integer.
[0066] S202. The average value Z of the inner and outer diameters of the nth partition. n The polar coordinate functions for determining the nth partition of the wafer are: the initial thickness function f(θ) and the target thickness function g(θ), which are the distances from points within the partition to the origin.
[0067] S203. The Princeton equation is used as the basic model to describe the material removal rate. According to the Princeton equation, the material removal rate is expressed as:
[0068] MRR = K × P × V
[0069] Where K is the Princeton coefficient, which depends on the characteristics of the polishing pad, workpiece material, and abrasive particles; P is the applied pressure; and V is the relative velocity. The Princeton coefficient includes the polishing slurry flow rate. Keeping all other factors constant, the above equation can be further rewritten as a composite function of the polishing slurry flow rate function F(θ):
[0070] RR(θ)=k F(θ)VP,
[0071] Where k is a new constant coefficient, polishing pressure P and relative speed V are both set values, and the polishing slurry flow rate function F(θ) is a periodic function of the wafer rotation angle θ. By establishing a periodic function of the wafer rotation angle θ, the flow rate of the polishing slurry supplied to the polishing pad is periodically controlled according to the wafer rotation angle, that is, the supply of polishing slurry is synchronized with the wafer rotation and controlled according to the circumferential thickness of the wafer. Preferably, the period of the polishing slurry flow rate function is 2π, so that the wafer rotation period and the polishing slurry flow rate control period are completely consistent, making the control more convenient and the processed wafer surface shape more accurate. Since the wafer notch position has been aligned with the polishing slurry supply device 20, this direction can be considered as having a phase difference of 0.
[0072] The constant coefficient in the material removal rate function is determined by trial polishing of wafers. Wafers from the same batch are polished for a specific time t0 using a constant pressure P0, constant relative velocity V0, and constant polishing fluid flow rate F0. The thickness before and after polishing is obtained using a thickness measuring device, and the thickness difference is calculated to obtain the material removal amount Δ0. The constant coefficient k can then be calculated using the formula Δ0 = t0kV0P0F0. If V and / or P are constant values during actual polishing, the product of these constant values and k can also be used as the overall coefficient.
[0073] In actual polishing, the wafer rotation speed ω h The polishing disc rotation speed is typically set to a constant value, thus simplifying the control of the polishing process through the polishing time t. The polishing pressure of the nth partition is controlled as follows: The material removal rate function for this partition can be further expressed as: Furthermore, since the wafer rotation speed and polishing disk rotation speed are set to constant, that is, the relative speed V is a constant value, the constant value kV can be used as an overall coefficient to determine through trial polishing.
[0074] The polishing fluid flow function is further expressed as In this trial polishing, the polishing slurry flow rate F0 is used as the base flow rate, and the polishing time t is also the wafer rotation time. A and These are the amplitude parameter and the phase parameter, respectively. It can be seen that F(t) is a period of 2π / ω. h The periodic function, the wafer rotation period and the control period of the polishing slurry flow rate remain completely consistent.
[0075] The following is based on the removal rate function RR(t). n The polishing fluid flow rate function F(t) is described in detail, along with the polishing steps and correction steps.
[0076] S204. One-step polishing process:
[0077] S2041. Assign initial values to the parameters in the polishing fluid flow function, that is, assign initial values A = A0 and A0 to the amplitude parameter and phase parameter.
[0078] S2042. According to the polishing fluid flow function Control the supply of polishing slurry, and control the polishing pressure of the nth zone to be [value missing]. Polishing wafer scheduled time t1.
[0079] S205. Calibration Procedure:
[0080] S2051. Obtain the material removal amount, feature point position, and removal amount for the nth partition in a single polishing operation.
[0081] The amount of material removed from the wafer in a single polishing step is calculated by the difference in wafer thickness before and after the first polishing step. The wafer thickness after the first polishing step is measured using a measuring device and expressed as the first polishing thickness function h(θ) with respect to the wafer rotation angle. Then, based on the initial thickness function f(θ) of the nth partition and the first polishing thickness function h(θ), the amount of material removed in the trial polishing of the nth partition can be expressed as Δ(θ) = h(θ) - f(θ).
[0082] Finding at least one extreme point of the function Δ(θ) yields the primary polishing feature point, determining its location and material removal amount. Preferably, the primary polishing feature point is the point with the minimum and / or maximum material removal amount in the nth partition during primary polishing. The location of the primary polishing feature point is expressed in polar coordinates as (Z... n The amount of feature points removed in one polishing operation is denoted as Δ1.
[0083] S2052. Obtain the location of the target feature points and the target removal amount based on the initial thickness function and the target thickness function.
[0084] Based on the initial thickness function f(θ) and the target thickness function g(θ) of the nth partition, the target material removal amount function H(θ) = g(θ) - f(θ) of the nth partition can also be expressed. By finding at least one extreme point corresponding to the function H(θ), the target feature point can be obtained, and the position and removal amount of the target feature point can be determined. Here, "correspondence" means that the feature point types in S1051 and S1052 should be the same, i.e., both are maximum points, and / or both are minimum points. The position of the target feature point is represented in polar coordinates (Z... n The amount of target feature points removed is denoted as Δ0.
[0085] S2053. Correct the phase parameter based on the position of the polishing feature point and the target feature point, and correct the amplitude parameter based on the removal amount of the polishing feature point and the removal amount of the target feature point. The corrected phase parameter is: The corrected amplitude parameter is A = A1 = A0·Δ1 / Δ0, thus obtaining the corrected polishing fluid flow function.
[0086] Optionally, by selecting both the maximum and minimum points as feature points, two intermediate phase parameters and intermediate amplitude parameters can be obtained using the above correction method. The average of the two intermediate phase parameters and intermediate amplitude parameters is calculated, and the two averages are used as the corrected phase parameters and corrected amplitude parameters, respectively, thereby obtaining the corrected polishing fluid flow function.
[0087] Optionally, a time coefficient can also be considered when correcting the amplitude parameter to balance the impact of different polishing times on the amplitude parameter. In one embodiment, the average material removal amount Δ can be calculated first based on the wafer surface shape to be polished and the wafer surface shape after polishing, and then the desired polishing time T can be calculated using the formula Δ = TkV0P0F0. Let the time coefficient m = T / t1, then the corrected amplitude parameter is... This embodiment discloses a single calibration of the polishing fluid flow function. Those skilled in the art will readily realize that increasing the number of trial polishing and calibrations can improve wafer processing accuracy. Therefore, the time coefficient can also be set to the desired number of calibrations.
[0088] S206. Keeping other polishing conditions unchanged, proceed according to the corrected polishing slurry flow function. A polishing slurry is supplied to perform secondary polishing on the wafer.
[0089] S207. After the second polishing, the wafer thickness is measured and compared with the target thickness function g(θ) to determine if it meets the target surface profile requirements. If it meets the target surface profile requirements, the polishing slurry flow rate function used is used as the processing polishing slurry flow rate function, which can be used to polish wafers in the same batch with the same initial and target surface profiles. If it does not meet the requirements, the phase and amplitude parameters are repeatedly corrected until a wafer that meets the target surface profile requirements is processed. It can be understood that the polishing slurry flow rate function after the m-th correction... Phase parameter A in m and amplitude parameters It is achieved by adjusting the phase parameter A in the polishing fluid flow function after the (m-1)th correction. m-1 and amplitude parameters It was obtained by correction.
[0090] Example 3
[0091] Figure 4 This is a schematic flowchart of another embodiment of the wafer polishing method of the present invention. Figure 4 As shown, except for step S1053, the other steps in Embodiment 3 are the same as those in Embodiment 2.
[0092] S3053. Correct the phase parameter based on the position of the polishing feature point and the position of the target feature point, and correct the amplitude parameter based on the removal amount of the polishing feature point, the corrected phase parameter, and the trial polishing time.
[0093] The method for correcting the phase parameters is the same as in step S2053, and the corrected phase parameters are as follows:
[0094] According to the material removal rate formula, the amount of material removed can be expressed as: Among them, T t This refers to the polishing time. The amount of feature point removed in one polishing pass (Δ1) and the corrected phase parameters are also considered. Substituting the polishing time t1 into the material removal formula, the corrected amplitude parameter A = A1 can be obtained.
[0095] It is understandable that the corrected amplitude parameter can also be solved through steps S2053 and S3053 respectively, and the result of the two calculations can be used as the final amplitude parameter A = A1.
[0096] The present invention also provides a wafer polishing unit 100 for performing the wafer polishing method of the present invention, such as... Figure 5As shown, the device includes: a polishing head 10, a polishing slurry supply device 20, a polishing pad 30, a trimming device 40, a detection device 50, a flow controller 60, and a wafer interaction device 70. The detection device 50 includes a first detection module 51 for determining wafer thickness and a second detection module 52 for detecting wafer notches. The first detection module 51 is preferably an optical ranging module disposed in the polishing pad 30, which can detect the distance to the wafer surface in real time through a transparent window on the polishing pad, thereby calculating the wafer thickness. The second detection module 52 is preferably a camera disposed on the wafer interaction device 70, which determines the position of the wafer notch by capturing images of the wafer, thereby determining the initial position of the wafer. The wafer to be polished is placed on the wafer interaction device 70, and the polishing head 10 can move between the polishing pad 30 and the wafer interaction device 70 to pick up the wafer from the wafer interaction device 70 and move it onto the polishing pad 30. The second detection module 52 is positioned above the wafer interaction device 70 to detect the notch position before the polishing head 10 picks up the wafer. The polishing head does not rotate before polishing begins, so detecting the notch position allows the determination of the notch angle when the wafer begins to rotate. This angle is relative to a predetermined direction, thus enabling a unified description of the wafer's initial thickness function f(θ), target thickness function g(θ), and polishing fluid flow rate function F. (θ) The flow controller 60 is preferably a programmable logic controller (PLC), electrically connected to the polishing slurry supply device 20, and used to control the supply of polishing slurry according to the polishing slurry flow rate function. The dressing device 40 is used to dress the polishing pad.
[0097] Optionally, the wafer interaction device 70 is a loading cup, including a rotating component for rotating the wafer to rotate it to a specific angle so that the notch faces a predetermined direction, i.e., the angle between the wafer and the predetermined direction is 0 when the wafer begins to rotate, thereby simplifying function calculations and control. Preferably, the predetermined direction is the direction in which the notch of the wafer faces the polishing slurry supply device 20 when the wafer is on the polishing disk.
[0098] The present invention also provides a wafer processing apparatus, such as... Figure 6 As shown, it includes a controller 200 and a wafer polishing unit 100. The controller is electrically connected to the wafer polishing unit 100 and is used to control the wafer polishing unit 100 to execute the wafer polishing method of the present invention.
[0099] The above embodiments are only used to illustrate the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of the present invention, and the patent protection scope of the embodiments of the present invention should be defined by the claims.
Claims
1. A wafer polishing method characterized by, include: The wafer dicing step involves a polishing head air film comprising N radially divided partitions with independently controllable polishing pressure. The wafer surface is divided in a manner that corresponds one-to-one with the partitions of the polishing head air film, where N≥1. The thickness function determination step involves obtaining the initial and target surface shapes of the nth partition on the wafer surface. These initial and target surface shapes are then processed by the initial thickness function after wafer partitioning. and target thickness function It means that, among them, It is the wafer rotation angle, N≥n≥1; The steps for determining the polishing slurry flow rate function include determining the material removal rate function for the nth partition on the wafer surface, where the material removal rate function is a composite function of the polishing slurry flow rate function and the polishing slurry flow rate function is related to the wafer rotation angle. A periodic function with a period of 2π ; In one polishing step, polishing fluid is supplied according to the polishing fluid flow function to polish the wafer; The calibration step involves calibrating the polishing fluid flow rate function based on the wafer surface profile after the first polishing, the initial thickness function, and the target thickness function. In the secondary polishing step, polishing slurry is supplied according to the corrected polishing slurry flow function to continue polishing the wafer.
2. The wafer polishing method as described in claim 1, characterized in that, The material removal rate function is a function determined according to the Princeton equation. Where k is a constant coefficient, P is the polishing pressure, and V is the relative velocity.
3. The wafer polishing method as described in claim 2, characterized in that, The material removal rate function for determining the nth partition on the wafer surface includes: Test polishing of the wafer, controlling the polishing pressure during the test polishing process. The polishing head rotation speed is The polishing disc rotation speed is The flow rate of the polishing fluid is Polishing time is ; The amount of material removed from the nth partition on the wafer surface is measured, and the constant coefficient k is calculated based on the material removal rate function.
4. The wafer polishing method as described in claim 3, characterized in that, Also includes: The polishing fluid flow function is expressed as a function of wafer rotation time. function , These are the amplitude parameter and the phase parameter, respectively.
5. The wafer polishing method as described in claim 4, characterized in that, The first polishing step includes: Assign initial values to the amplitude and phase parameters. ; Polishing the wafer, during the polishing process, controlling the polishing pressure of the nth partition to be... The polishing head rotation speed is The polishing disc rotation speed is and according to the polishing fluid flow function Supply polishing fluid.
6. The wafer polishing method as described in claim 5, characterized in that, The step of correcting the polishing fluid flow function includes: Measure the amount of material removed during the first polishing of the nth partition on the wafer surface, and obtain the position and amount of material removed from the feature points of the first polishing. The location and removal amount of the target feature points are obtained based on the initial thickness function and the target thickness function; The amplitude parameter is corrected based on the position of the primary polishing feature point and the position of the target feature point; the phase parameter is corrected based on the removal amount of the primary polishing feature point and the removal amount of the target feature point; and / or The amplitude parameter is corrected based on the position of the polishing feature point and the position of the target feature point, and the amplitude parameter is also corrected based on the removal amount of the polishing feature point, the material removal rate function, the corrected phase parameter, and the polishing time.
7. The wafer polishing method according to any one of claims 1-6, characterized in that, Also includes: A wafer angle detection and rotation step is used to detect the angle of the wafer in order to rotate the wafer to a specific angle before the first polishing step.
8. The wafer polishing method as described in claim 7, characterized in that, Also includes: The wafer surface profile inspection step involves inspecting the wafer surface profile after the secondary polishing step. If the surface profile does not meet the target thickness function, the polishing slurry flow rate function correction step and the secondary polishing step are repeated.
9. A wafer polishing unit for performing the wafer polishing method as described in any one of claims 1-8, characterized in that, include: The wafer polishing method includes a polishing head, a polishing disc, a detection device, a polishing slurry supply device, and a flow controller. The detection device includes a first detection module for measuring wafer thickness, and the flow controller controls the polishing slurry supply device to supply polishing slurry according to the polishing slurry flow rate function in any one of claims 1-8.
10. The wafer polishing unit as described in claim 9, characterized in that, It also includes a wafer interaction device, which is used to carry the wafer and interact with the polishing head on the wafer; The detection device further includes a second detection module, which is used to detect the angle of the wafer carried on the wafer interaction device; The wafer interaction device includes a rotating component, and the rotating component and the second detection module are used to rotate the wafer to a predetermined angle.
11. A wafer processing apparatus, characterized in that, The device includes a controller and a wafer polishing unit as described in any one of claims 9-10, wherein the controller is electrically connected to the wafer polishing unit and is used to control the wafer polishing unit to perform the wafer polishing method as described in any one of claims 1-8.