Wafer polishing method, polishing unit and processing equipment

Abstract

The invention discloses a wafer polishing method, a polishing unit and processing equipment, and the wafer polishing method comprises the steps that a wafer is divided into N subareas in a one-to-one correspondence mode with the subareas of a polishing head gas film, and each subarea of the polishing head gas film independently controls the polishing pressure; obtaining an initial surface type and a target surface type of the nth partition of the wafer, wherein the initial surface type and the target surface type are represented by an initial thickness function and a target thickness function after partition; a material removal rate function of the nth partition of the wafer is determined, the material removal rate function is a composite function about a polishing solution flow function, and the polishing solution flow function is a periodic function about the rotation angle theta of the wafer; a polishing solution is supplied according to the polishing solution flow function for trial grinding of the wafer, and the polishing solution flow function is corrected according to the trial grinding result, the initial thickness function and the target thickness function; and the polishing liquid is supplied according to the corrected polishing liquid flow function so as to continue to polish the wafer. The wafer polishing method provided by the invention can realize the processing of the wafer with a specific surface type.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical mechanical polishing, and more particularly, relates to a wafer polishing method, a polishing unit and a processing device. Background Art

[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 process steps in the entire manufacturing process is increasing. Facing various polishing requirements for different wafer surface profiles, the existing processing methods cannot meet the processing needs of wafers with specific surface profiles. Summary of the Invention

[0003] In view of this, the present invention provides a wafer polishing method, a polishing unit and a polishing device, so as to solve or at least alleviate one or more of the above problems and other problems existing in the prior art.

[0004] To achieve the foregoing object, a first aspect of the present invention provides a wafer polishing method, including:

[0005] A wafer partitioning step, wherein the polishing head air film includes N partitions that are radially partitioned and can independently control the polishing pressure. The wafer is partitioned in a one-to-one correspondence with the partitions of the polishing head air film, and N≥1;

[0006] A step of determining the thickness function, obtaining the initial surface profile and the target surface profile of the nth partition on the wafer surface, and the initial surface profile and the target surface profile are represented by an initial thickness function f(θ) and a target thickness function g(θ) after wafer partitioning, where θ is the wafer rotation angle, and N≥n≥1;

[0007] A step of determining the polishing liquid flow rate function, determining the material removal rate function of the nth partition on the wafer surface, where the material removal rate function is a composite function of the polishing liquid flow rate function, and the polishing liquid flow rate function is a periodic function F(θ) with a period of 2π with respect to the wafer rotation angle θ;

[0008] A correction step, supplying the polishing liquid to polish the wafer according to the polishing liquid flow rate function, and correcting the polishing liquid flow rate function according to the trial polishing result, the initial thickness function and the target thickness function;

[0009] A polishing step, supplying the polishing liquid according to the corrected polishing liquid flow rate function to continue polishing the wafer.

[0010] For the wafer polishing method as described above, 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 speed.

[0011] The wafer polishing method as described above, optionally, the material removal rate function for determining the nth partition on the wafer surface includes: controlling the polishing pressure to be P0, the rotational speed of the polishing head to be ω h , the rotational speed of the polishing platen to be ω p , the flow rate of the polishing liquid to be F0, polishing the wafer for a specific time T t , measuring the material removal amount of the nth partition on the wafer surface, and calculating the constant coefficient k according to the material removal rate function.

[0012] The wafer polishing method as described above, optionally, further includes: expressing the polishing liquid flow rate function as a function of the wafer rotation time t A and are respectively the amplitude parameter and the phase parameter.

[0013] The wafer polishing method as described above, optionally, supplying the polishing liquid to grind the wafer according to the polishing liquid flow rate function includes:

[0014] Assigning initial values A = A0 and

[0015] Controlling the polishing pressure of the nth partition Z n to be the rotational speed of the polishing head to be ω h , the rotational speed of the polishing platen to be ω p , and supplying the polishing liquid according to the polishing liquid flow rate function .

[0016] The wafer polishing method as described above, optionally, correcting the polishing liquid flow rate function according to the grinding result, the initial thickness function, and the target thickness function includes:

[0017] Measuring the material removal amount after grinding the nth partition, and obtaining the position and the removal amount of the grinding characteristic point;

[0018] Obtaining the position and the target removal amount of the target characteristic point according to the initial target function and the target thickness function;

[0019] Correcting the amplitude parameter according to the position of the characteristic point after grinding and the position of the target characteristic point, and correcting the phase parameter according to the removal amount after grinding and the target removal amount; and / or,

[0020] Correcting the amplitude parameter according to the position of the characteristic point after grinding and the position of the target characteristic point, and correcting the amplitude parameter according to the removal amount after grinding, the corrected phase parameter, and the grinding time.

[0021] The wafer polishing method as described above, optionally, the characteristic point is the minimum point and / or the maximum point of the material removal amount.

[0022] The wafer polishing method as described above, optionally, further includes: detecting the angle of the wafer to rotate the wafer before the first polishing step to a specific angle.

[0023] The wafer polishing method as described above, optionally, further includes: detecting the surface profile of the wafer after the polishing step is completed, and if it does not conform to the target thickness function, repeating the correction step and the polishing step.

[0024] The second aspect of the present invention provides a wafer polishing unit, including: a polishing head, a polishing platen, a detection device, a polishing liquid supply device, and a flow controller. The detection device includes a first detection module for measuring the thickness of the wafer, and the flow controller is used to control the polishing liquid supply device to supply polishing liquid according to the polishing liquid flow function in the wafer polishing method as described in the first aspect.

[0025] The wafer polishing unit as described above, optionally, further includes a wafer interaction device, and the wafer interaction device is used to carry the wafer and interact with the polishing head for the wafer;

[0026] The detection device further includes a second detection module, and the second detection module is used to detect the angle of the wafer carried on the wafer interaction device;

[0027] The wafer interaction device includes a rotation component, and the rotation component and the second detection device are used to rotate the wafer to a predetermined angle.

[0028] The third aspect of the present invention provides a wafer processing device, including a controller and the wafer polishing unit as described in the second aspect. The controller is electrically connected to the wafer polishing unit and is used to control the wafer polishing unit to execute 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 achieve the processing of wafers with a specific surface profile. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings.

[0031] Figure 1 is a schematic diagram of a wafer polishing unit in the prior art.

[0032] Figure 2 is a schematic flow chart of the first embodiment of the wafer polishing method of the present invention.

[0033] Figure 3It is a schematic flow chart of the second embodiment of the wafer polishing method of the present invention.

[0034] Figure 4 It is a schematic flow chart of the third embodiment of the wafer polishing method of the present invention.

[0035] Figure 5 It is a schematic diagram of the wafer polishing unit of the present invention.

[0036] Figure 6 It is a schematic diagram of the wafer processing equipment of the present invention.

[0037] Reference numerals: polishing head 10; polishing liquid supply device 20; polishing pad 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 manners

[0038] In order 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 in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art shall fall within the protection scope of the embodiments of the present invention.

[0039] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0040] In addition, in the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it may be a mechanical connection or an electrical connection, or it may be the communication inside two elements. It may be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0041] Figure 1It is a schematic diagram of a wafer polishing unit in the prior art. As shown in the figure, an air film and a retaining ring surrounding the air film are provided on the lower surface of the polishing head 10. The polishing head can adsorb the wafer to be polished through the air film and confine the wafer inside the retaining ring. The polishing liquid supply device 20 disperses the polishing liquid on the surface of the polishing pad covering the polishing disc 30. The dressing device 40 includes a dressing arm and a dressing head. The dressing arm drives the rotating dressing head to swing to dress the surface of the polishing pad to a state suitable for polishing. During the polishing operation, the polishing head presses the surface to be polished of the wafer against the surface of the rotating polishing pad and rotates and moves. The polishing liquid is distributed between the polishing pad and the wafer, and the removal of the surface material of the wafer is completed under the action of chemical mechanics to achieve the purpose of global and local planarization.

[0042] However, with the continuous advancement of the process nodes, various new materials and methods of depositing on the wafer surface emerge in an endless stream, requiring the wafer surface to exhibit non-uniformity, that is, specific surface profiles need to be processed on the wafer. The existing equipment and methods can no longer meet the processing requirements.

[0043] The present invention provides a wafer polishing method, which realizes different material removal amounts in the circumferential direction of the wafer by controlling the flow rate of the polishing liquid, so as to realize the processing of a specific surface profile of the wafer.

[0044] Embodiment 1

[0045] Figure 2 It is a schematic flow diagram of an embodiment of the wafer polishing method of the present invention. As Figure 2 shown, the wafer polishing method includes the following steps:

[0046] S101. Wafer partitioning step. In the wafer partitioning step, the wafer surface is radially divided into N partitions in a one-to-one correspondence with the air film of the polishing head, where N is a positive integer.

[0047] The air film of the polishing head includes N partitions divided radially. The innermost partition is circular, and the other partitions are annular. Each partition communicates with an independent gas flow path, so that the pressure inside the partition air film can be independently controlled, and thus the polishing pressure applied to the wafer can be controlled according to the partitioning of the air film of the polishing head. The wafer is partitioned in a one-to-one correspondence with the partitions of the air film of the polishing head, so that the polishing pressure of different regions in the radial direction of the wafer can be determined according to the partitions. The partitioning method of the polishing head can refer to other current technologies and is not limited herein. The polishing pressure of the nth partition from the inside to the outside is expressed as

[0048] S102. Step of determining the thickness function. In the step of determining the thickness function, the initial surface profile and the target surface profile of the nth partition on the wafer surface are obtained. The initial surface profile and the target surface profile are represented by the initial thickness function f(θ) and the target thickness function g(θ) after wafer partitioning, where θ is the wafer rotation angle.

[0049] The surface profile of the wafer can be represented by the thickness function of the wafer. The initial thickness function represents the thickness distribution of the wafer to be polished, that is, the initial surface profile. The thickness of the wafer can be obtained by using existing thickness detection methods, such as optical detection, acoustic detection, etc., which are not limited here. Usually, 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, that is, the target surface profile expected to be processed, which is determined by the processing requirements of the wafer. It can be directly generated according to the processing requirements or obtained by measuring the thickness of the finished product.

[0051] An initial angle of 0 can be determined on the wafer. Any point (d, θ) on the wafer surface can be determined by the distance d from the center of the wafer and the rotation angle θ relative to the initial angle. That is, a thickness function f(d, θ) can be established with the center of the wafer 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 from the points in the nth partition to the center of the wafer is regarded as a fixed value Z n , and the points in the nth partition can be represented by (Z n , θ). Z n is preferably the average value of the inner diameter and the outer diameter 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. Step of determining the polishing liquid flow function. In the step of determining the polishing liquid flow function, the material removal rate function and the polishing liquid flow function of the nth partition on the wafer surface are determined simultaneously, where the material removal rate function is a composite function of the polishing liquid flow function, and the polishing liquid flow function is a periodic function F(θ) of the wafer rotation angle θ with a period of 2π.

[0053] The unit of the Material Removal Rate (MRR) is usually expressed as a volume unit divided by a time unit, which is used to describe the volume of material that can be removed per unit time. There are various models for describing the material removal rate in chemical mechanical polishing to characterize the relationship between various factors affecting the material removal rate and the material removal rate. Select one of the material removal rate models that includes the factor of polishing liquid flow rate and can be expressed by a function as the basic model of the present invention, and rewrite the function therein as a composite function RR(θ) = α·F(θ) of the polishing liquid flow rate function as the material removal rate function of the present invention, where α is a coefficient characterizing other factors affecting the material removal rate.

[0054] S104. Primary polishing step. In the primary polishing step, supply the polishing liquid to the polishing pad according to the polishing liquid flow rate function determined in S104, while controlling other factors affecting the material removal rate to be unchanged or at a fixed value to ensure the solvability of the material removal rate function, and polish the wafer for a predetermined time.

[0055] S105. Calibration step. In the calibration step, calibrate the polishing liquid flow rate function F(θ) according to the wafer surface profile after polishing in S104, the initial thickness function f(θ), and the target thickness function g(θ).

[0056] As an example, the polishing liquid flow rate function F(θ) includes at least one parameter, and the polishing liquid flow rate function F(θ) is calibrated by correcting the value of the parameter.

[0057] S106. Secondary polishing step. In the secondary polishing step, supply the polishing liquid to the polishing pad according to the calibrated polishing liquid flow rate function, while controlling other factors affecting the material removal rate to be the same as in S104, and continue to polish the wafer for a predetermined time.

[0058] Through steps S101 - S106, the wafer polishing method of the present invention can process wafers with a specific surface profile, especially wafers with a specific thickness distribution in the circumferential direction of the wafer.

[0059] Optionally, before step S101, there is also step S100, wafer angle detection and rotation step. In the wafer angle detection and rotation step, detect the attitude of the wafer to determine the initial angle of the wafer, so as to rotate the wafer before the primary polishing step to a specific angle, preferably such that the initial phase differences of the initial thickness function, the target thickness function, and the polishing liquid flow rate function are 0.

[0060] As an example, the edge of the wafer has a notch. Before starting the polishing, the notch direction of the wafer is adjusted to face a fixed direction, so that the polishing fluid 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 when the wafer starts polishing, it faces the supply position of the polishing fluid, so that the initial phase of the polishing fluid flow function is 0, simplifying the control during the polishing process. Further, when processing wafers of the same batch into a consistent specific target surface shape, the initial angles of all wafers are the same.

[0061] Optionally, after step S106, a wafer surface shape detection step is further included. The surface shape of the wafer that has completed secondary polishing in step S106 is detected. If the measured surface shape does not conform to the target thickness function, step S105 is repeated to correct the polishing fluid flow function again, and step S106 is performed to supply the polishing fluid according to the re-corrected polishing fluid flow function to continue polishing the wafer.

[0062] Embodiment 2

[0063] Figure 3 is a schematic flow chart 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 in conjunction with Embodiment 2. As Figure 3 shown, the wafer polishing method includes the following steps:

[0064] S200. Detect the wafer notch, use the center of the wafer as the origin, and the radius from the origin to the notch as the polar coordinate axis; rotate the wafer to rotate the notch direction of the wafer to align with the polishing fluid supply device 20.

[0065] S201. Divide the wafer into zones, and divide the wafer surface into N equal-width zones along the radial direction in a one-to-one correspondence with the air film of the polishing head, where N is a positive integer.

[0066] S202. Take the average value Z of the inner diameter and the outer diameter of the nth zone n as the distance from the points in this zone to the origin, and determine the polar coordinate functions of the nth zone of the wafer: the initial thickness function f(θ) and the target thickness function g(θ).

[0067] S203. Use the Preston equation as the basic model for describing the material removal rate. According to the Preston equation, the material removal rate is expressed as:

[0068] MRR = K × P × V

[0069] Among them, K is the Princeton coefficient, which depends on the characteristics of the polishing pad, the workpiece material, and the abrasive particles. P is the applied pressure, and V is the relative velocity. The Princeton coefficient includes the polishing liquid flow rate factor. By keeping other factors constant except the polishing liquid flow rate, the above formula can be further rewritten as a composite function of the polishing liquid flow rate function F(θ):

[0070] RR(θ) = kF(θ)VP,

[0071] where k is a new constant coefficient, the polishing pressure P and the relative velocity V are both set values, and the polishing liquid 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 liquid supplied to the polishing pad is controlled periodically according to the rotation angle of the wafer, that is, the supply of the polishing liquid is controlled according to the circumferential thickness of the wafer synchronously with the rotation of the wafer. Preferably, the period of the polishing liquid flow rate function is 2π, so that the rotation period of the wafer and the control period of the polishing liquid flow rate are exactly the same, making the control more convenient and the surface profile of the processed wafer more accurate. Since the position of the wafer notch has been aligned with the polishing liquid supply device 20, this direction can be considered to have a phase difference of 0.

[0072] The constant coefficient in the material removal rate function is determined by the method of trial polishing of wafers. Wafers of the same batch are polished for a specific time t0 with a constant pressure P0, a constant relative velocity V0, and a constant polishing liquid flow rate F0. The thickness before and after polishing is obtained by a thickness measuring device and the thickness difference is calculated to obtain the material removal amount Δ0. Then, according to the formula Δ0 = t0kV0P0F0, the constant coefficient k can be calculated. If V and / or P is a fixed value during actual polishing, the product of the fixed value and k can also be used as an overall coefficient.

[0073] During actual polishing, the wafer rotation speed ω h and the polishing platen rotation speed are usually set as fixed values, so as to simplify the control of the polishing process by the polishing time t. The polishing pressure of the nth partition is controlled to be The material removal rate function of this partition can be further expressed as In addition, since the wafer rotation speed and the polishing platen rotation speed are set to be constant, that is, the relative velocity V is a fixed value, the fixed value kV can be used as an overall coefficient and determined by trial polishing.

[0074] The polishing liquid flow rate function is also further expressed as where the polishing liquid flow rate F0 in the trial polishing is used as the basic polishing liquid flow rate, and the polishing time t is also the wafer rotation time. A and are the amplitude parameter and the phase parameter respectively. It can be seen that F(t) is a periodic function with a period of 2π / ω h The rotation period of the wafer and the control period of the polishing liquid flow rate still remain exactly the same.

[0075] Next, according to the removal rate function RR(t) n and the polishing slurry flow rate function F(t), the first polishing step and the correction step will be described in detail.

[0076] S204. First polishing step:

[0077] S2041. Assign initial values to the parameters in the polishing slurry flow rate function, that is, assign the initial values of the amplitude parameter and the phase parameter as A = A0 and

[0078] S2042. Control the supply amount of the polishing slurry according to the polishing slurry flow rate function and control the polishing pressure of the nth partition to be polish the wafer for a predetermined time t1.

[0079] S205. Correction step:

[0080] S2051. Obtain the material removal amount, the position and the removal amount of the characteristic point of the first polishing of the nth partition.

[0081] The material removal amount of the wafer in the first polishing step is calculated by the difference in the wafer thickness before and after the first polishing. Measure the thickness of the wafer after the first polishing using a measuring device and express it as a first polishing thickness function h(θ) with respect to the wafer rotation angle. Then, according to the initial thickness function f(θ) and the first polishing thickness function h(θ) of the nth partition, the trial grinding material removal amount of the nth partition can be expressed as Δ(θ) = h(θ) - f(θ).

[0082] Find at least one extreme point of the function Δ(θ), the first polishing characteristic point can be obtained, and the position and the removal amount of the first polishing characteristic point are determined. Preferably, the first polishing characteristic point is the minimum point and / or the maximum point of the material removal amount of the first polishing of the nth partition. The position of the first polishing characteristic point is represented in polar coordinates as (Z n , θ1), and the removal amount of the first polishing characteristic point is denoted as Δ1.

[0083] S2052. Obtain the position and the target removal amount of the target characteristic point according to the initial thickness function and the target thickness function.

[0084] According to 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 obtaining at least one extreme point corresponding to the function H(θ), the target feature points can be obtained, and the positions and removal amounts of the target feature points can be determined. The correspondence here means that the types of feature points in S1051 and S1052 should be the same, that is, both are maximum points, and / or both are minimum points. The position of the target feature point is represented in polar coordinates as (Z n , θ0), and the removal amount of the target feature point is denoted as Δ0.

[0085] S2053. Calibrate the phase parameter according to the positions of the primary polishing feature points and the target feature points, and calibrate the amplitude parameter according to the removal amounts of the primary polishing feature points and the target feature points. The calibrated phase parameter is The calibrated amplitude parameter is A = A1 = A0·Δ1 / Δ0, so as to obtain the calibrated polishing liquid flow function

[0086] Optionally, if both the maximum point and the minimum point are selected as feature points at the same time, two intermediate phase parameters and intermediate amplitude parameters can be obtained according to the above calibration method. The averages of the two intermediate phase parameters and intermediate amplitude parameters are calculated respectively, and the two averages are used as the calibrated phase parameter and the calibrated amplitude parameter respectively, so as to obtain the calibrated polishing liquid flow function.

[0087] Optionally, a time coefficient can also be considered when calibrating the amplitude parameter to balance the influence of different primary polishing times on the amplitude parameter. In one embodiment, the average material removal amount Δ can be calculated first according to the surface profile of the wafer to be polished and the surface profile of the polished wafer, and then the expected polishing time T can be calculated through the formula Δ = TkV0P0F0. Let the time coefficient m = T / t1, then the calibrated amplitude parameter is In this embodiment, the calibration of the polishing liquid flow function is disclosed once. Those skilled in the art can easily think of increasing the number of trial grinding and calibration to improve the wafer processing accuracy, and the time coefficient can also be set as the expected number of calibrations.

[0088] S206. Keep other polishing conditions unchanged, and supply the polishing liquid according to the calibrated polishing liquid flow function to perform secondary polishing on the wafer.

[0089] S207. After the secondary polishing is completed, the thickness of the wafer is measured and compared with the target thickness function g(θ) to determine whether the target surface profile requirements are met. If the target surface profile requirements are met, the polishing fluid flow rate function used can be used as the processing polishing fluid flow rate function for polishing wafers of the same batch with the same initial surface profile and target surface profile. If the requirements are not met, the phase parameter and amplitude parameter are corrected repeatedly until a wafer that meets the target surface profile requirements is processed. It can be understood that the phase parameter A in the m polishing fluid flow rate function after the m-th correction and the amplitude parameter m-1 are obtained by correcting the phase parameter A and the amplitude parameter in the polishing fluid flow rate function after the (m - 1)-th correction.

[0090] Embodiment III

[0091] Figure 4 is a schematic flow chart of another embodiment of the wafer polishing method of the present invention. As Figure 4 shown, the other steps of Embodiment III are the same as those of Embodiment II except for step S1053.

[0092] S3053. Correct the phase parameter according to the positions of the primary polishing feature points and the target feature points, and correct the amplitude parameter according to the removal amount of the primary polishing feature points, the corrected phase parameter, and the trial grinding time.

[0093] The method for correcting the phase parameter is the same as that in step S2053, and the corrected phase parameter is

[0094] According to the material removal rate formula, the material removal amount can be expressed as where T t is the polishing time. Substituting the removal amount Δ1 of the primary polishing feature points, the corrected phase parameter and the time t1 of the polished wafer into the material removal amount formula, the corrected amplitude parameter can be solved as A = A1.

[0095] It can be understood that the corrected amplitude parameter can also be solved through steps S2053 and S3053 respectively, and the operation results of the two are 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, as Figure 5As shown in the figure, it includes: a polishing head 10, a polishing liquid supply device 20, a polishing pad 30, a dressing 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 the thickness of the wafer and a second detection module 52 for detecting the notch of the wafer. The first detection module 51 is preferably an optical ranging module disposed in the polishing pad 30, and the distance from the wafer surface can be detected in real time through a transparent window on the polishing pad, so as to calculate the thickness of the wafer. The second detection module 52 is preferably a camera disposed on the wafer interaction device 70, and the position of the wafer notch is determined by capturing the image of the wafer, so as to determine 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 adsorb the wafer from the wafer interaction device 70 and move it to the polishing pad 30. The second detection module 52 is disposed above the wafer interaction device 70 to detect the notch position before the polishing head 10 adsorbs the wafer. The polishing head does not rotate before starting polishing, so that the angle of the notch when the wafer starts to rotate can be determined when the notch position is detected. The angle is the angle relative to a predetermined direction, so that the initial thickness function f(θ), the target thickness function g(θ), and the polishing liquid flow function F of the wafer can be uniformly described. (θ) . The flow controller 60 is preferably a programmable logic controller (PLC), electrically connected to the polishing liquid supply device 20, and is used to control the supply amount of the polishing liquid according to the polishing liquid flow 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 assembly for rotating the wafer to rotate the wafer to a specific angle so that the notch faces the predetermined direction, that is, the angle between the wafer and the predetermined direction when the wafer starts to rotate is 0, so as to simplify the function operation and control. Preferably, the predetermined direction is the direction in which the notch of the wafer faces the polishing liquid supply device 20 when the wafer is on the polishing pad.

[0098] The present invention also provides a wafer processing device, as Figure 6 shown, including 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, rather than to limit the embodiments of the present invention. Those of ordinary skill in the relevant technical field can also 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 belong to the scope of the embodiments of the present invention. The patent protection scope of the embodiments of the present invention shall be defined by the claims.

Claims

1. A wafer polishing method, characterized in that, Including: A wafer dividing step, where the air film of the polishing head includes N partitions that are divided radially and can independently control the polishing pressure. The wafer surface is divided in a one-to-one correspondence with the partitions of the air film of the polishing head, and N≥1; A step of determining the thickness function, obtaining the initial surface profile and the target surface profile of the nth partition on the wafer surface. The initial surface profile and the target surface profile are represented by the initial thickness function f(θ) and the target thickness function g(θ) after wafer partitioning, where θ is the wafer rotation angle, and N≥n≥1; A step of determining the polishing liquid flow rate function, determining 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 liquid flow rate function, and the polishing liquid flow rate function is a periodic function F(θ) with a period of 2π with respect to the wafer rotation angle θ; A primary polishing step of supplying polishing liquid according to the polishing liquid flow rate function to polish the wafer; A correction step of correcting the polishing liquid flow rate function according to the wafer surface profile after the primary polishing, the initial thickness function, and the target thickness function; A secondary polishing step of supplying polishing liquid according to the corrected polishing liquid flow rate function to continue polishing the wafer.

2. The wafer polishing method according to claim 1, wherein, 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 speed.

3. The wafer polishing method according to claim 2, wherein The step of determining the material removal rate function of the nth partition on the wafer surface includes: Test polishing of wafers. During the test polishing process, the polishing pressure is controlled to be P0 and the polishing head speed is controlled to be ω h , polishing disc speed is ω p , polishing liquid flow is F0, polishing time is T t ; Measuring the material removal amount of the nth partition on the wafer surface, and calculating the constant coefficient k according to the material removal rate function.

4. The wafer polishing method according to claim 3, wherein Also including: Express the polishing liquid flow rate function as a function of the wafer rotation time t A and are the amplitude parameter and the phase parameter respectively.

5. The wafer polishing method according to claim 4, wherein, The primary polishing step includes: Assign initial values A = A0 to the amplitude parameter and the phase parameter, and A polished wafer, controlling the polishing pressure of the nth partition during the polishing process to be The polishing head rotation speed is ω h , and the polishing pad rotation speed is ω p , and supplying the polishing liquid according to the polishing liquid flow rate function .

6. The wafer polishing method according to claim 5, wherein The step of correcting the polishing liquid flow rate function includes: Measuring the material removal amount of the nth partition on the wafer surface during the primary polishing, and obtaining the position and removal amount of the primary polishing characteristic points; Obtaining the position and removal amount of the target characteristic points according to the initial target function and the target thickness function; Correcting the amplitude parameter according to the position of the primary polishing characteristic points and the position of the target characteristic points, and correcting the phase parameter according to the removal amount of the primary polishing characteristic points and the removal amount of the target characteristic points; and / or, Correcting the amplitude parameter according to the position of the primary polishing characteristic points and the position of the target characteristic points, and correcting the amplitude parameter according to the removal amount of the primary polishing characteristic points, the material removal rate function, the corrected phase parameter, and the primary polishing time.

7. The wafer polishing method according to claim 5, characterized in that, The characteristic points are the minimum points and / or the maximum points of the material removal amount.

8. The wafer polishing method according to any one of claims 1-7, characterized in that, Also including: A wafer angle detection and rotation step for detecting the angle of the wafer to rotate the wafer before the primary polishing step to a specific angle.

9. The wafer polishing method according to claim 8, wherein, Also including: A wafer surface profile detection step of detecting the wafer surface profile after the secondary polishing step. If it does not meet the target thickness function, the steps of correcting the polishing liquid flow rate function and the secondary polishing step are repeated.

10. A wafer polishing unit for performing the wafer polishing method according to any one of claims 1-9, characterized in that, Including: A polishing head, a polishing pad, a detection device, a polishing liquid supply device, and a flow controller. The detection device includes a first detection module for measuring the thickness of a wafer, and the flow controller is configured to control the polishing liquid supply device to supply polishing liquid according to the polishing liquid flow function in the wafer polishing method according to any one of claims 1-9.

11. The wafer polishing unit according to claim 10, wherein, It further includes a wafer interaction device, which is configured to carry the wafer and interact with the polishing head for the wafer; The detection device further includes a second detection module, which is configured 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 configured to rotate the wafer to a predetermined angle.

12. A wafer processing apparatus, characterized in that, It includes a controller and a wafer polishing unit according to any one of claims 10-11, characterized in that the controller is electrically connected to the wafer polishing unit and is configured to control the wafer polishing unit to execute the wafer polishing method according to any one of claims 1-9.

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