Polishing control method, apparatus, and chemical mechanical polishing apparatus

Abstract

The application relates to a polishing control method, device and chemical mechanical polishing equipment. The method comprises the following steps: performing a first polishing stage chemical mechanical polishing operation on a target wafer; stopping the first polishing stage chemical mechanical polishing operation when it is detected that the surface thickness of the target wafer reaches a target endpoint thickness; and performing a second polishing stage chemical mechanical polishing operation on the target wafer, wherein the target endpoint thickness is determined based on the metal line density corresponding to the target wafer, and the down pressure of the first polishing stage is greater than that of the second polishing stage. The method can improve the surface thickness flatness of the target wafer after the whole chemical mechanical polishing process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, and in particular, to a polishing control method and device and a chemical mechanical polishing apparatus. BACKGROUND

[0002] Chemical mechanical polishing (CMP) is a process used to planarize wafer surfaces in semiconductor manufacturing. CMP combines the effects of chemical etching and mechanical polishing to remove excess material from the surface of a wafer, providing a flat surface for subsequent photolithography and etching processes.

[0003] In the related art, a wafer to be polished is sequentially subjected to high downward force (HDF) and low downward force (LDF) polishing on a first polishing platform to remove copper on the surface of the wafer, and then the wafer is transferred to a second polishing platform to polish off tantalum (Ta), tantalum nitride (TaN), titanium nitride (TiN), and a portion of buried dielectric film (BD Film) on the surface of the wafer.

[0004] However, the wafer after the above polishing process has a low surface flatness and is prone to metal residue, resulting in a low yield of the wafer. SUMMARY

[0005] Therefore, it is necessary to provide a polishing control method, device and chemical mechanical polishing apparatus capable of improving the surface flatness of a wafer after polishing to solve the above technical problems.

[0006] In a first aspect, the present application provides a polishing control method, comprising:

[0007] performing a first polishing stage of chemical mechanical polishing operation on a target wafer;

[0008] stopping the first polishing stage of chemical mechanical polishing operation when it is detected that the surface thickness of the target wafer reaches a target endpoint thickness, the target endpoint thickness being determined based on a metal line density corresponding to the target wafer;

[0009] performing a second polishing stage of chemical mechanical polishing operation on the target wafer, the downward force in the first polishing stage being greater than the downward force in the second polishing stage.

[0010] In one of the embodiments, the determination of the target endpoint thickness comprises:

[0011] obtaining a metal line density corresponding to the target wafer;

[0012] The target endpoint thickness corresponding to the target wafer is obtained based on the metal line density corresponding to the target wafer and the preset endpoint mapping relationship. The endpoint mapping relationship includes a mapping relationship between the metal line density and an endpoint thickness used to detect the end of the first polishing stage.

[0013] In one of the embodiments, the endpoint mapping relationship includes that an endpoint thickness corresponding to a first metal line density is less than an endpoint thickness corresponding to a second metal line density, and the first metal line density is greater than the second metal line density.

[0014] In one of the embodiments, the endpoint mapping relationship includes a linear negative correlation relationship between the endpoint thickness and the metal line density.

[0015] In one of the embodiments, the target endpoint thickness corresponding to the target wafer is obtained based on the metal line density corresponding to the target wafer and the preset endpoint mapping relationship, and includes:

[0016] The initial endpoint thickness is obtained based on the metal line density corresponding to the target wafer and the endpoint mapping relationship.

[0017] The first polishing stage of the chemical mechanical polishing operation is performed on the test wafer, and when it is detected that the surface thickness of the test wafer reaches the initial endpoint thickness, the first polishing stage of the chemical mechanical polishing operation is stopped, a first measured thickness corresponding to the test wafer is obtained, and the test wafer and the target wafer belong to the same batch of wafers.

[0018] The target endpoint thickness is obtained by compensating the initial endpoint thickness based on the first measured thickness.

[0019] In one of the embodiments, the polishing head includes a plurality of polishing areas, and the first measured thickness includes a first area measured thickness corresponding to each polishing area.

[0020] The target endpoint thickness is obtained by compensating the initial endpoint thickness based on the first measured thickness, and includes:

[0021] A first area deviation corresponding to each polishing area is obtained according to a difference between each first area measured thickness and the initial endpoint thickness.

[0022] The target endpoint thickness is obtained based on the first area deviation corresponding to each polishing area and the initial endpoint thickness, and the target endpoint thickness includes a target endpoint sub-thickness corresponding to each polishing area.

[0023] In one of the embodiments, after the polishing device replaces the polishing head or the polishing pad, the method further includes:

[0024] The first polishing stage of the chemical mechanical polishing operation is stopped when it is detected that the surface thickness of the updated wafer reaches the target endpoint thickness, and a second measured thickness corresponding to the updated wafer is obtained, the updated wafer being the first wafer after the updated polishing head or polishing pad, and the updated wafer and the target wafer belonging to the same batch;

[0025] The target endpoint thickness is updated based on the second measured thickness to obtain an updated target endpoint thickness.

[0026] In one embodiment, the polishing head includes a plurality of polishing areas, the second measured thickness includes a second area measured thickness corresponding to each polishing area, and the target endpoint thickness includes a target endpoint sub-thickness corresponding to each polishing area;

[0027] The target endpoint thickness is updated based on the second measured thickness to obtain an updated target endpoint thickness, including:

[0028] A second area deviation corresponding to each polishing area is obtained according to a difference between each second area measured thickness and the target endpoint thickness;

[0029] Each target endpoint sub-thickness is updated based on the second area deviation corresponding to each polishing area to obtain an updated target endpoint sub-thickness.

[0030] In a second aspect, the present application also provides a polishing control device, which includes:

[0031] A first polishing execution module is configured to perform a first polishing stage of a chemical mechanical polishing operation on a target wafer;

[0032] A polishing end detection module is configured to stop the first polishing stage of the chemical mechanical polishing operation when it is detected that the surface thickness of the target wafer reaches a target endpoint thickness, and the target endpoint thickness is determined based on a metal line density corresponding to the target wafer;

[0033] A second polishing execution module is configured to perform a second polishing stage of the chemical mechanical polishing operation on the target wafer, and a downforce of the first polishing stage is greater than a downforce of the second polishing stage.

[0034] In a third aspect, the present application also provides a chemical mechanical polishing device, which includes a polishing head, a polishing pad, and a controller, the controller including a memory and a processor, the memory storing a computer program, and the processor being configured to execute the computer program to perform the steps of the method of the first aspect.

[0035] The aforementioned grinding control method, apparatus, and chemical mechanical polishing (CMP) equipment perform a first-stage CMP operation on a target wafer. When the surface thickness of the target wafer is detected to have reached the target endpoint thickness, the first-stage CMP operation is stopped, and a second-stage CMP operation is performed. The target endpoint thickness is determined based on the metal line density corresponding to the target wafer, and the downward pressure in the first stage is greater than that in the second stage. Thus, during the first-stage CMP operation on the target wafer, the endpoint of the first stage is detected based on the target endpoint thickness determined by the metal line density corresponding to the target wafer. This improves the uniformity of the surface copper thickness of the target wafer after the first stage, improves the surface flatness of the target wafer after the entire CMP process, and increases the wafer yield. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a diagram illustrating the application environment of the grinding control method in one embodiment;

[0038] Figure 2 A schematic diagram of a chemical mechanical polishing process performed on a first polishing platform, provided as an embodiment;

[0039] Figure 3 Example of a graphical representation of a CP on a wafer surface free of metal residue;

[0040] Figure 4 for Figure 3 The wafer surface shown is a submicroscopic structure with a resolution of 50 nm under TEM.

[0041] Figure 5 CP Map for a wafer surface containing metal residue;

[0042] Figure 6 for Figure 5 The wafer surface shown is a submicroscopic structure with a resolution of 100 nm under TEM.

[0043] Figure 7 for Figure 5 The defect map shown is the wafer surface.

[0044] Figure 8A flowchart of a polishing control method provided for one embodiment;

[0045] Figure 9 A schematic diagram of surface thickness uniformity of a wafer before polishing in one embodiment;

[0046] Figure 10 A schematic diagram of surface thickness uniformity of a wafer before polishing in one embodiment; Figure 9 A schematic diagram of surface copper removal uniformity of a wafer after the end of the HDF polishing stage;

[0047] Figure 11 A schematic diagram of surface copper removal uniformity of a wafer after the end of the HDF polishing stage; Figure 10 A data analysis cake chart of a wafer;

[0048] Figure 12 A flowchart of obtaining a target endpoint thickness in one embodiment;

[0049] Figure 13 An exemplary linear regression curve of endpoint thickness and metal line density;

[0050] Figure 14 A flowchart of obtaining a target endpoint thickness in another embodiment;

[0051] Figure 15 A schematic diagram of a region structure of a polishing head in one embodiment;

[0052] Figure 16 A flowchart of obtaining a target endpoint thickness in another embodiment;

[0053] Figure 17 A flowchart of obtaining an updated target endpoint thickness in one embodiment;

[0054] Figure 18 A flowchart of obtaining updated target endpoint sub-thicknesses in one embodiment;

[0055] Figure 19 A cake chart obtained by data analysis of copper thickness on a wafer surface at the end of a first polishing stage in a polishing control method provided by one exemplary embodiment of the present application;

[0056] Figure 20 An internal structure diagram of a computer device in one embodiment. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0058] The grinding control method provided in this application embodiment can be applied to, for example... Figure 1 The controller in the grinding equipment shown Figure 1 In the (not shown) configuration, the controller is connected at least to the polishing head 102, the polishing slurry arm 104, the dresser 106, and the resistance eddy current monitor 108 (RECM). The polishing head 102, also called the polishing head or carrier head, serves as a wafer carrier during the polishing process. It serves two purposes: firstly, to fix the wafer 110, ensuring its stability and preventing slippage or movement during polishing; and secondly, to apply pressure to the wafer 110, ensuring close contact between the wafer surface and the polishing pad 112, promoting uniform material removal. The polishing pad 112, also called a pad, is sprayed and channeled by the polishing slurry arm 104 onto its surface. The corrosiveness of the polishing slurry 114 and the unevenness of the polishing pad 112 abrade the wafer surface, resulting in a flattened surface. The dresser 106 continuously or intermittently adjusts the polishing pad to extend its lifespan.

[0059] The resistance eddy current monitor 108 is mainly used for real-time detection of thickness changes and uniformity of the polished surface. Specifically, the resistance eddy current monitor 108 measures the thickness of the material being polished by measuring resistance changes. Through multi-point monitoring, the resistance eddy current monitor 108 can also detect the removal rate in different areas and adjust polishing parameters based on feedback. In the polishing control process of wafer 110, the resistance eddy current monitor 108 is used for end-point detection (EPD).

[0060] In related technologies, the wafer to be polished is first polished on a first polishing platform (also known as Table A, abbreviated as TA) using high down force (HDF) to quickly remove most of the copper (CU) on the wafer surface, and then polished using low down force (LDF) to remove the remaining copper on the wafer surface. For an example, please refer to... Figure 2 This is a schematic diagram of a chemical mechanical polishing process performed on a first polishing platform, as provided in one embodiment; Figure 2 As shown in (a), the copper thickness on the surface of the wafer to be polished is approximately 8000 Å. After the HDF polishing stage, as shown in (a), Figure 2 As shown in (b), the copper thickness remaining on the wafer surface is approximately 1400 angstroms. The copper on the wafer surface is removed through the LDF stage, as... Figure 2In addition, the LDF stage is performed for an additional 25 seconds (s) or other preset over polish (OP) time after the EPD monitoring of the surface copper removal. Then the wafer is transferred from the first polishing platform to a second polishing platform (also referred to as Table B, TB) to polish the surface Ta, TaN, TiN and a portion of the BD Film. However, the polished wafer surface obtained after the above polishing process is prone to copper residue.

[0061] Referring to Figure 3 , a CP (Chip Probing) map of a wafer surface without metal residue is shown, and the corresponding Figure 4 , a CP map of a wafer surface with metal residue is shown, and the corresponding Figure 3 , a sub-microstructure of the wafer surface shown in is 50 nm (nanometer) resolution under TEM (Transmission Electron Microscope), and the position indicated by the green arrow corresponds to a wafer surface without TiN residue; please refer to Figure 5 , a CP map of a wafer surface with metal residue is shown, and the corresponding Figure 6 , a sub-microstructure of the wafer surface shown in is 100 nm resolution under TEM, and the position indicated by the red arrow corresponds to a wafer surface with TiN residue, which is prone to cause circuit pattern short circuit; Figure 5 , a sub-microstructure of the wafer surface shown in is 100 nm resolution under TEM, and the position indicated by the red arrow corresponds to a wafer surface with TiN residue, which is prone to cause circuit pattern short circuit; Figure 7 , a Defect Map of the wafer surface shown in, that is Figure 5 , the black dot in Figure 7 represents the position of TiN residue, Figure 7 , the Defect Map and Figure 5 , the CP Map have 3 circles in common. At present, improving the flatness of the wafer after chemical mechanical polishing and thus improving the yield of the wafer is a problem to be solved in the field.

[0062] In an exemplary embodiment, referring to Figure 8 , a polishing control method is provided, and the method is applied to the controller in the application environment shown in Figure 1 . As shown in Figure 8 , the polishing control method provided includes steps 802 to 806, wherein:

[0063] Step 802, performing a first polishing stage of chemical mechanical polishing operation on a target wafer.

[0064] The target wafer refers to the wafer currently undergoing chemical mechanical polishing; the downward pressure in the first polishing stage is greater than the downward pressure in the second polishing stage in subsequent step 806, that is, the first polishing stage corresponds to the HDF polishing stage, and the second polishing stage corresponds to the LDF polishing stage.

[0065] Step 804: When the surface thickness of the target wafer is detected to have reached the target endpoint thickness, the chemical mechanical polishing operation of the first polishing stage is stopped.

[0066] The target endpoint thickness is determined based on the metal line density of the target wafer. Metal line density can also be called the copper fill rate of the wafer; the higher the metal line density, the more copper needs to be filled; conversely, the lower the metal line density, the less copper needs to be filled.

[0067] For example, since wafers in the same batch have the same product parameters, i.e., the corresponding metal line density is the same, it is sufficient to obtain the target endpoint thickness once for wafers in the same batch.

[0068] By dissecting each polishing step of the TA+TB polishing platform and analyzing the wafer surface flatness after each polishing step, it was found that wafers with poor final surface flatness already exhibited this problem after the HDF polishing step on the TA platform. Further investigation confirmed that the final defect location exhibited a low-rate phenomenon at the end of the HDF polishing stage, and the surface thickness uniformity deteriorated at the end of the HDF polishing stage. This deterioration corresponded to the location of the three-ring defect, and significant vibration was observed at the beginning and end of the cake pattern corresponding to the polishing endpoint. Please refer to [reference needed]. Figure 9 This refers to the thickness uniformity of a wafer before grinding. Figure 10 This diagram illustrates the uniformity of copper removal during the HDF polishing stage on the TA polishing platform for this wafer. The three vertical bars of different colors correspond to... Figure 7 The location of the 3rd ring of the defect; Figure 11 for Figure 10 The cake diagram shown corresponds to the wafer. The horizontal axis represents the wafer diameter position data in millimeters, and the vertical axis represents the induced voltage value of RECM in volts. The cake diagram is a visualization tool used in chemical mechanical polishing (CMP) processes to display the relative magnitude and distribution characteristics of various signals (such as vibration, pressure, and removal rate). Figure 9 The horizontal axis represents the position data along the wafer diameter, in millimeters, and the vertical axis represents the thickness data of the copper on the wafer surface, in angstroms. Figure 10 The horizontal axis represents the positional data along the wafer diameter, in millimeters, and the vertical axis represents the amount of copper removed during the HDF polishing stage, in angstroms.

[0069] Based on this, the applicant believes that the removal amount of the unevenly polished copper at the end of the HDF polishing stage is less, and the remaining copper leads to the decrease of the final wafer surface flatness. In the embodiments of the present application, the control process of the first polishing stage is adjusted to improve the uniformity of the wafer surface copper thickness at the end of the first polishing stage, thereby improving the uniformity of the wafer surface at the end of the overall polishing process.

[0070] It is found through analysis of the various control amounts of the first polishing stage that, in the process of end point detection, different end point thicknesses are set for the RECM, and the uniformity of the wafer surface copper thickness obtained after polishing is different. It is found through analysis of the polishing results of wafers with different metal line densities in the first polishing stage that, for different metal line densities, the end point detection thickness corresponding to the metal line density can improve the uniformity of the wafer surface copper thickness at the end of the first polishing stage.

[0071] In a possible implementation, as shown in Figure 12 the determination process of the target end point thickness includes:

[0072] In step 1202, the metal line density corresponding to the target wafer is obtained.

[0073] In step 1204, the target end point thickness corresponding to the target wafer is obtained based on the metal line density corresponding to the target wafer and the preset end point mapping relationship.

[0074] The end point mapping relationship includes the mapping relationship between the metal line density and the end point thickness used to detect the end of the first polishing stage.

[0075] In a possible implementation of the present embodiment, the end point mapping relationship includes that the end point thickness corresponding to the first metal line density is less than the end point thickness corresponding to the second metal line density, and the first metal line density is greater than the second metal line density. It can be understood that the relationship between the end point mapping relationship and the metal line density and the end point thickness is negatively correlated.

[0076] For example, as shown in Figure 13 the metal line density and the end point thickness are linearly and negatively correlated; Figure 13 is an exemplary linear regression curve of the end point thickness and the metal line density. The optimal end point thickness corresponding to multiple different metal line densities is obtained through experiments, and the linear regression curve equation of the end point thickness and the metal line density is y=-43.864x+4914, where the vertical coordinate y represents the end point thickness, the unit is angstrom, the horizontal coordinate x represents the metal line density, the unit is %, -43.864 represents the correlation slope of the end point thickness and the metal line density, and 4194 represents the correlation factor, Figure 13The linear correlation corresponding to the linear regression curve shown is 0.7362. In this example, the optimal end point thickness refers to setting the end point thickness in the end point detection algorithm corresponding to the first polishing stage to the optimal end point thickness for the case where the metal line density is A, and the uniformity of the copper on the wafer surface after the first polishing stage is improved compared to other end point thickness values.

[0077] In application, the embodiment can determine the corresponding end point mapping relationship in advance for specific polishing equipment test. When the polishing equipment is applied for chemical mechanical polishing, the target end point thickness of the target wafer corresponding batch is determined according to the metal line density of the target wafer and the preset end point mapping relationship, so as to improve the wafer surface uniformity of the first polishing stage.

[0078] In a possible implementation manner of the embodiment, the end point mapping relationship includes that the end point thickness corresponding to the first metal line density is less than or equal to the end point thickness corresponding to the second metal line density, and the first metal line density is greater than the second metal line density.

[0079] In the implementation manner, the end point mapping relationship can be in the form of a segmented function or a lookup table. The wafers with the metal line density belonging to the same density interval correspond to the same end point thickness.

[0080] Step 806, performing the second polishing stage of the chemical mechanical polishing operation on the target wafer.

[0081] The polishing control method provided by the above embodiment stops the chemical mechanical polishing operation of the first polishing stage when the surface thickness of the target wafer reaches the target end point thickness, and performs the second polishing stage of the chemical mechanical polishing operation on the target wafer, wherein the target end point thickness is determined based on the metal line density corresponding to the target wafer, and the down pressure of the first polishing stage is greater than the down pressure of the second polishing stage; in this way, during the first polishing stage of the chemical mechanical polishing operation on the target wafer, the first polishing stage of the target wafer is polished based on the target end point thickness determined by the metal line density corresponding to the target wafer, the uniformity of the surface copper thickness of the target wafer after the first polishing stage is improved, and the surface thickness uniformity of the target wafer after the entire chemical mechanical polishing process is improved, and the yield of the wafer is improved.

[0082] In an exemplary embodiment, the polishing control method provided is related to the process of obtaining the target end point thickness of the target wafer based on the metal line density corresponding to the target wafer and the preset end point mapping relationship. Please refer to Figure 14 The process includes steps 1402 to 1406, wherein:

[0083] At step 1402, the initial endpoint thickness is obtained based on the metal line density corresponding to the target wafer and the endpoint mapping relationship.

[0084] For example, the metal line density corresponding to the target wafer is directly brought into the linear regression curve equation shown in the figure to calculate the initial endpoint thickness. Figure 13

[0085] At step 1404, the first-stage chemical mechanical polishing operation is performed on the test wafer, and the first-stage chemical mechanical polishing operation is stopped when it is detected that the surface thickness of the test wafer reaches the initial endpoint thickness, so as to obtain the first measured thickness corresponding to the test wafer.

[0086] In the embodiment, the test wafer and the target wafer belong to the same batch of wafers, that is, the metal line densities corresponding to the test wafer and the target wafer are the same; and the test wafer can be a wafer in a test batch corresponding to the target wafer.

[0087] The applicant found in experiments and applications that when the endpoint thickness of the EPD algorithm is set to a numerical value B, the RECM performs endpoint detection based on the numerical value B during the chemical mechanical polishing, and after the completion of the first-stage polishing, the optical instrument is used to measure the copper thickness of the wafer surface, and it is found that there is a certain error between the actual measured thickness and the numerical value B. Please refer to Table 1. In the process of high downforce polishing, the RECM is used to detect the copper thickness of the wafer surface and the optical instrument is used to measure the surface copper thickness according to a plurality of preset polishing times; it can be seen from Table 1 that there is a deviation between the RECM detection value and the actual wafer surface copper thickness (i.e. the optical instrument measurement value). In Table 1, the units of the RECM detection value, the optical instrument measurement value and the deviation are Angstroms.

[0088] Table 1

[0089]

[0090] In the embodiment, the endpoint thickness in the RECM is set to the initial endpoint thickness obtained based on the metal line density corresponding to the target wafer and the endpoint mapping relationship, the initial endpoint thickness is used to polish the test wafer in the first-stage polishing, and the surface copper thickness of the polished test wafer is measured as the first measured thickness.

[0091] At step 1406, the initial endpoint thickness is compensated based on the first measured thickness to obtain the target endpoint thickness.

[0092] In a possible implementation, the process of compensating the initial endpoint thickness based on the first measured thickness to obtain the target endpoint thickness includes: subtracting the initial endpoint thickness from the first measured thickness to obtain an overall deviation value; and subtracting the overall deviation value from the initial endpoint thickness to obtain the target endpoint thickness. ​

[0093] For example, the initial endpoint thickness is 3500 angstroms, the first measured thickness is 3600 angstroms, the overall deviation value is 100 angstroms, and the target endpoint thickness is 3400 angstroms.

[0094] In another possible implementation, the process of compensating the initial endpoint thickness based on the first measured thickness to obtain the target endpoint thickness includes: subtracting the initial endpoint thickness from the first measured thickness to obtain an overall deviation value; multiplying the overall deviation value by a preset compensation weight to obtain a compensation deviation value; and subtracting the compensation deviation value from the initial endpoint thickness to obtain the target endpoint thickness.

[0095] For example, the initial endpoint thickness is 3500 angstroms, the first measured thickness is 3600 angstroms, the overall deviation value is 100 angstroms, and the target endpoint thickness is 3400 angstroms.

[0096] In another possible implementation, the polishing head includes a plurality of polishing regions. For example, referring to FIG. 6, the polishing head includes a polishing region C1 (Central 1 Region), a polishing region C2 (Central 2 Region), a polishing region RAP (Retaining Area Pad), a polishing region EAP (Edge Area Pad), and a polishing region OAP (Outer Area Pad). For example, in a polishing head with a radius of 150 mm, taking the center of the polishing head as the coordinate origin and the tangential direction with a radius from 0 mm to 150 mm, the region range of the polishing region C1 is 0 mm to 32.3 mm, the region range of the polishing region C2 is 32.3 mm to 91.7 mm, the region range of the polishing region RAP is 91.7 mm to 119.6 mm, the region range of the polishing region EAP is 119.6 mm to 137.5 mm, and the region range of the polishing region OAP is 137.5 mm to 150 mm. Figure 15 In this implementation, the first measured thickness includes a first region measured thickness corresponding to each polishing region. For example, referring to FIG. 6, the first measured thickness includes a first region measured thickness C1, a first region measured thickness C2, a first region measured thickness RAP, a first region measured thickness EAP, and a first region measured thickness OAP corresponding to the polishing region C1, the polishing region C2, the polishing region RAP, the polishing region EAP, and the polishing region OAP, respectively.

[0097] Figure 16 In this implementation, the process of compensating the initial endpoint thickness based on the first measured thickness to obtain the target endpoint thickness includes steps 1602 and 1604, wherein:

[0098] In step 1602, a first region deviation corresponding to each polishing region is obtained according to the difference between each first region measured thickness and the initial endpoint thickness. ​

[0099] Exemplarily, the first region thickness of each first region is subtracted by the initial endpoint thickness respectively to obtain a first region deviation of each polishing region respectively.

[0100] At step 1604, the target endpoint thickness is obtained based on the first region deviation of each polishing region and the initial endpoint thickness, wherein the target endpoint thickness includes a target endpoint sub-thickness corresponding to each polishing region respectively.

[0101] Exemplarily, the thickness of the test wafer before polishing is 8000 angstroms, and the initial endpoint thickness determined according to the metal line density is 1400 angstroms, that is, the RECM detection is stopped when the test wafer is polished to a surface copper thickness of 1400 angstroms; at this time, the surface copper thickness of the test wafer is measured, and it is found that the surface copper thickness corresponding to the polishing region RAP is 1600 angstroms, and then the target endpoint sub-thickness corresponding to the polishing region RAP is set to 1200 angstroms, and in the polishing process, the down pressure corresponding to the polishing region RAP is increased to 1200 angstroms, so that the entire wafer reaches 1400 angstroms after the first polishing stage is completed, thereby improving the surface uniformity of the wafer after polishing.

[0102] In the above embodiment, based on the first measurement thickness of the test wafer, the deviation value between the detection thickness of the RECM of each polishing region and the actual thickness of the wafer surface copper is obtained, the initial endpoint thickness obtained according to the preset endpoint mapping relationship is compensated, and the target endpoint thickness including the target endpoint sub-thickness corresponding to each polishing region is obtained; in this way, the initial endpoint thickness is compensated according to the polishing condition of each polishing region, thereby improving the uniformity of the wafer surface after polishing.

[0103] The polishing control method provided in the above embodiment compensates the initial endpoint thickness according to the first measurement thickness of the test wafer of the same batch as the target wafer to obtain the target endpoint thickness, thereby avoiding the influence of the detection accuracy of the RECM on the uniformity of the wafer surface after polishing.

[0104] In an exemplary embodiment, please refer to Figure 17 The polishing control method provided in the above embodiment further includes steps 1702 to 1704 after the polishing equipment replaces the polishing head or the polishing pad, wherein:

[0105] At step 1702, the first polishing stage of the chemical mechanical polishing operation is performed on the update wafer, and when the surface thickness of the update wafer reaches the target endpoint thickness, the first polishing stage of the chemical mechanical polishing operation is stopped to obtain a second measurement thickness corresponding to the update wafer.

[0106] The update wafer is the first wafer after the update of the polishing head or the polishing pad, and the update wafer and the target wafer belong to the same batch.

[0107] The embodiment measures the post-grinding surface thickness of the first wafer after the polishing equipment replaces the polishing head or the polishing pad, to confirm the influence of the new polishing head or the polishing pad on the RECM.

[0108] At step 1704, the target endpoint thickness is updated according to the second measured thickness, to obtain an updated target endpoint thickness.

[0109] After the influence of the new polishing head or the polishing pad on the endpoint detection of the RECM is quantified based on the second measured thickness, the target endpoint thickness is updated based on the second measured thickness, to avoid the influence of the new polishing head or the polishing pad on the accuracy of the endpoint detection of the polishing, and to improve the surface uniformity of the polishing result.

[0110] In one possible implementation, the process of updating the target endpoint thickness based on the second measured thickness to obtain an updated target endpoint thickness includes: subtracting the target endpoint thickness from the second measured thickness to obtain an update deviation value; and subtracting the update deviation value from the target endpoint thickness to update the target endpoint thickness, to obtain the updated target endpoint thickness.

[0111] In another possible implementation, the process of updating the target endpoint thickness based on the second measured thickness to obtain an updated target endpoint thickness includes: subtracting the target endpoint thickness from the second measured thickness to obtain an update deviation value; multiplying the update deviation value by a preset update weight to obtain a weighted deviation value; and subtracting the weighted deviation value from the target endpoint thickness to update the target endpoint thickness, to obtain the updated target endpoint thickness.

[0112] In another possible implementation, the polishing head includes a plurality of polishing zones, and the second measured thickness includes a plurality of second regional measured thicknesses respectively corresponding to the polishing zones, and the target endpoint thickness includes a plurality of target endpoint sub-thicknesses respectively corresponding to the polishing zones. In this implementation, please refer to Figure 18 The process of updating the target endpoint thickness based on the second measured thickness to obtain an updated target endpoint thickness includes steps 1802 to 1804, in which:

[0113] At step 1802, a second regional deviation corresponding to each polishing zone is obtained according to the difference between each second regional measured thickness and the target endpoint thickness.

[0114] At step 1804, each target endpoint sub-thickness is updated based on the second regional deviation corresponding to each polishing zone, to obtain an updated target endpoint sub-thickness.

[0115] In this embodiment, based on the second measured thickness of the update wafer, the deviation value between the detected thickness of the RECM of each polishing area and the actual thickness of the wafer surface copper is obtained, and the target endpoint sub-thickness of each polishing area is updated to improve the uniformity of the wafer surface after polishing.

[0116] In one exemplary embodiment, a polishing control method is provided, and the method is applied to Figure 1 The controller in the application environment shown is taken as an example for illustration. The method comprises steps S2 to S22, wherein:

[0117] In step S2, the metal line density corresponding to the target wafer is obtained.

[0118] In step S4, based on the metal line density corresponding to the target wafer and the endpoint mapping relationship, the initial endpoint thickness is obtained.

[0119] In step S6, the test wafer is subjected to the first polishing stage of the chemical mechanical polishing operation, and when the surface thickness of the test wafer reaches the initial endpoint thickness, the first polishing stage of the chemical mechanical polishing operation is stopped, the first measured thickness corresponding to the test wafer is obtained, and the test wafer and the target wafer belong to the same batch of wafers.

[0120] In step S8, according to the difference between each first area measured thickness and the initial endpoint thickness, the first area deviation corresponding to each polishing area is obtained.

[0121] In step S10, based on the first area deviation corresponding to each polishing area and the initial endpoint thickness, the target endpoint thickness is obtained, and the target endpoint thickness includes the target endpoint sub-thickness corresponding to each polishing area.

[0122] In step S12, the target wafer is subjected to the first polishing stage of the chemical mechanical polishing operation.

[0123] In step S14, when the surface thickness of the target wafer reaches the target endpoint thickness, the first polishing stage of the chemical mechanical polishing operation is stopped, and the target endpoint thickness is determined based on the metal line density corresponding to the target wafer.

[0124] In step S16, the target wafer is subjected to the second polishing stage of the chemical mechanical polishing operation, and the down pressure of the first polishing stage is greater than that of the second polishing stage.

[0125] In step S18, after the polishing device replaces the polishing head or the polishing pad, the update wafer is subjected to the first polishing stage of the chemical mechanical polishing operation, and when the surface thickness of the update wafer reaches the target endpoint thickness, the first polishing stage of the chemical mechanical polishing operation is stopped, the second measured thickness corresponding to the update wafer is obtained, the update wafer is the first wafer after the update of the polishing head or the polishing pad, and the update wafer and the target wafer belong to the same batch.

[0126] In step S20, the second area deviation corresponding to each polishing area is obtained according to the difference between the measured thickness of each second area and the target endpoint thickness.

[0127] In step S22, the target endpoint sub-thicknesses are updated based on the second area deviation corresponding to each polishing area, to obtain updated target endpoint sub-thicknesses.

[0128] Figure 19 For the application of the polishing control method provided in the embodiment, the cake diagram of the copper thickness of the wafer surface at the end of the first polishing stage is obtained by data analysis. Compared with the copper thickness uniformity of the wafer surface at the end of the first polishing stage shown in FIG. 6, the copper thickness uniformity of the wafer surface at the end of the first polishing stage is better. Figure 11 , Figure 19 Figure 19 In the cake diagram, the abscissa is the position data in the diameter direction of the wafer, and the unit is millimeter; and the ordinate is the induced voltage value of the RECM, and the unit is volt.

[0129] It should be understood that, although each step in the flowchart involved in the above embodiments is displayed in sequence according to the arrow, these steps are not necessarily executed in sequence according to the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other sequences. Moreover, at least part of the steps in the flowchart involved in the above embodiments can include multiple steps or stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least part of other steps or steps or stages in other steps.

[0130] It can be understood that the term "based on" used in the present application is used to describe one or more factors that affect the determination, and does not exclude other factors that can affect the determination. For example, the phrase "determining A based on B" means that the determination of A can be based entirely or at least partially on factor B, that is, B is one factor that affects the determination of A, but does not exclude that the determination of A is also based on C.

[0131] Based on the same inventive concept, the present application also provides a polishing control device for implementing the above-mentioned polishing control method. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme described in the above method, so the specific limitations in one or more polishing control device embodiments provided below can refer to the limitations of the polishing control method in the above text, which will not be repeated here.

[0132] ​In one example embodiment, a polishing control device is provided, comprising: a first polishing execution module, a polishing end detection module, and a second polishing execution module, wherein:

[0133] The first polishing execution module is configured to perform a first polishing stage of chemical mechanical polishing operation on a target wafer.

[0134] The polishing end detection module is configured to stop the first polishing stage of chemical mechanical polishing operation when detecting that a surface thickness of the target wafer reaches a target endpoint thickness, the target endpoint thickness being determined based on a metal line density corresponding to the target wafer.

[0135] The second polishing execution module is configured to perform a second polishing stage of chemical mechanical polishing operation on the target wafer, the down force of the first polishing stage being greater than the down force of the second polishing stage.

[0136] In one example embodiment, the polishing end detection module is configured to obtain the metal line density corresponding to the target wafer; determine the target endpoint thickness corresponding to the target wafer based on the metal line density corresponding to the target wafer and a preset endpoint mapping relationship; and the endpoint mapping relationship comprises a mapping relationship between the metal line density and an endpoint thickness used for detecting the end of the first polishing stage.

[0137] In one example embodiment, the endpoint mapping relationship comprises that an endpoint thickness corresponding to a first metal line density is less than an endpoint thickness corresponding to a second metal line density, the first metal line density being greater than the second metal line density.

[0138] In one example embodiment, the endpoint mapping relationship comprises a linear negative correlation between the endpoint thickness and the metal line density.

[0139] In one example embodiment, the polishing end detection module is configured to determine an initial endpoint thickness based on the metal line density corresponding to the target wafer and the endpoint mapping relationship; the first polishing execution module is configured to perform the first polishing stage of chemical mechanical polishing operation on a test wafer; the polishing end detection module is configured to stop the first polishing stage of chemical mechanical polishing operation when detecting that a surface thickness of the test wafer reaches the initial endpoint thickness, to obtain a first measured thickness corresponding to the test wafer, the test wafer and the target wafer belonging to the same batch of wafers, and to compensate the initial endpoint thickness based on the first measured thickness to obtain the target endpoint thickness.

[0140] In an example embodiment, the polishing head comprises a plurality of polishing areas, the first measured thickness comprises a first area measured thickness corresponding to each of the polishing areas respectively, the polishing end detection module is configured to obtain a first area deviation corresponding to each of the polishing areas according to a difference between the first area measured thickness and the initial end thickness, and obtain a target end thickness based on the first area deviation corresponding to each of the polishing areas and the initial end thickness, the target end thickness comprises a target end sub-thickness corresponding to each of the polishing areas respectively.

[0141] In an example embodiment, after the polishing device replaces the polishing head or the polishing pad, the first polishing execution module is configured to perform a first polishing stage of chemical mechanical polishing operation on an updated wafer, the polishing end detection module is configured to stop the first polishing stage of chemical mechanical polishing operation when detecting that a surface thickness of the updated wafer reaches the target end thickness, obtain a second measured thickness corresponding to the updated wafer, and update the target end thickness based on the second measured thickness to obtain an updated target end thickness, the updated wafer is the first wafer after the updated polishing head or the polishing pad, and the updated wafer and the target wafer belong to the same batch.

[0142] In an example embodiment, the polishing head comprises a plurality of polishing areas, the second measured thickness comprises a second area measured thickness corresponding to each of the polishing areas respectively, and the target end thickness comprises a target end sub-thickness corresponding to each of the polishing areas respectively, the polishing end detection module is configured to obtain a second area deviation corresponding to each of the polishing areas according to a difference between the second area measured thickness and the target end thickness, and update each of the target end sub-thickness based on the second area deviation corresponding to each of the polishing areas to obtain an updated target end sub-thickness.

[0143] Each of the above modules in the polishing control device can be realized by software, hardware, and a combination thereof in whole or in part. Each of the above modules can be embedded in or independent of a processor in a computer device in hardware form, or can be stored in a memory in a computer device in software form, so as to be called and executed by a processor to perform operations corresponding to each of the above modules.

[0144] In an example embodiment, a chemical mechanical polishing device is provided, please refer to Figure 1 The device comprises a polishing head, a polishing pad, and a controller (not shown in the figure), the controller comprises a memory and a processor, the memory stores a computer program, and the processor executes the computer program to perform the steps in each of the above method embodiments.

[0145] In an example embodiment, a computer device is provided, which can be a controller in a chemical mechanical polishing device, and its internal structure diagram can be as shown in Figure 20As shown in the figure. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through the system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capability. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store the data required to be called when the grinding control method is executed. The input / output interface of the computer device is used to exchange information between the processor and the external device. The communication interface of the computer device is used to communicate with the terminal outside through the network connection. The computer program is executed by the processor to realize a kind of grinding control method.

[0146] Those skilled in the art can understand that, Figure 20 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0147] In one embodiment, a computer readable storage medium is provided, which stores a computer program. The computer program is executed by a processor to realize the steps in each method embodiment described above.

[0148] In one embodiment, a computer program product is provided, which includes a computer program. The computer program is executed by a processor to realize the steps in each method embodiment described above.

[0149] It should be noted that the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or authorized by all parties, and the collection, use and processing of related data need to comply with relevant regulations.

[0150] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiments of the methods can be included. Any reference to memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0151] Any combination of the technical features of the above embodiments can be made. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist, it should be considered as the scope of the present application.

[0152] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A polishing control method characterized by, The method comprises: performing a first polishing stage of a chemical mechanical polishing operation on a target wafer; stopping the first polishing stage of the chemical mechanical polishing operation when detecting that a surface thickness of the target wafer reaches a target endpoint thickness, the target endpoint thickness being determined based on a metal line density corresponding to the target wafer; performing a second polishing stage of the chemical mechanical polishing operation on the target wafer, a downforce of the first polishing stage being greater than a downforce of the second polishing stage.

2. The method of claim 1, wherein, The determination process of the target endpoint thickness comprises: obtaining a metal line density corresponding to the target wafer; obtaining a target endpoint thickness corresponding to the target wafer based on the metal line density corresponding to the target wafer and a preset endpoint mapping relationship, the endpoint mapping relationship comprising a mapping relationship between a metal line density and an endpoint thickness used for detecting an endpoint of the first polishing stage.

3. The method of claim 2, wherein, The endpoint mapping relationship comprises that an endpoint thickness corresponding to a first metal line density is less than an endpoint thickness corresponding to a second metal line density, the first metal line density being greater than the second metal line density.

4. The method of claim 2, wherein, The endpoint mapping relationship comprises a linear negative correlation relationship between an endpoint thickness and a metal line density.

5. The method of claim 2, wherein, The obtaining of the target endpoint thickness based on the metal line density corresponding to the target wafer and the preset endpoint mapping relationship comprises: obtaining an initial endpoint thickness based on the metal line density corresponding to the target wafer and the endpoint mapping relationship; performing the first polishing stage of the chemical mechanical polishing operation on a test wafer, stopping the first polishing stage of the chemical mechanical polishing operation when detecting that a surface thickness of the test wafer reaches the initial endpoint thickness, obtaining a first measured thickness corresponding to the test wafer, the test wafer and the target wafer belonging to a same batch of wafers; compensating the initial endpoint thickness based on the first measured thickness to obtain the target endpoint thickness.

6. The method of claim 5, wherein, The first measured thickness comprises a first area measured thickness corresponding to each of a plurality of polishing areas of a polishing head; The compensating of the initial endpoint thickness based on the first measured thickness to obtain the target endpoint thickness comprises: obtaining a first area deviation corresponding to each of the polishing areas according to a difference between each of the first area measured thicknesses and the initial endpoint thickness; obtaining the target endpoint thickness based on the first area deviation corresponding to each of the polishing areas and the initial endpoint thickness, the target endpoint thickness comprising a target endpoint sub-thickness corresponding to each of the polishing areas.

7. The method of claim 1, wherein, After replacing a polishing head or a polishing pad of a polishing device, the method further comprises: performing the first polishing stage of the chemical mechanical polishing operation on an updated wafer, stopping the first polishing stage of the chemical mechanical polishing operation when detecting that a surface thickness of the updated wafer reaches the target endpoint thickness, obtaining a second measured thickness corresponding to the updated wafer, the updated wafer being a first wafer after updating the polishing head or the polishing pad, the updated wafer and the target wafer belonging to a same batch; updating the target endpoint thickness based on the second measured thickness to obtain an updated target endpoint thickness.

8. The method of claim 7, wherein, The polishing head comprises a plurality of polishing areas, the second measured thicknesses comprise second area measured thicknesses corresponding to the respective polishing areas, and the target endpoint thicknesses comprise target endpoint sub-thicknesses corresponding to the respective polishing areas; The updating of the target endpoint thicknesses based on the second measured thicknesses comprises: obtaining second area deviations corresponding to the respective polishing areas according to differences between the respective second area measured thicknesses and the target endpoint thicknesses; and updating the target endpoint sub-thicknesses based on the second area deviations corresponding to the respective polishing areas to obtain updated target endpoint sub-thicknesses.

9. A grinding control device characterized by comprising: The polishing control device comprises: a first polishing execution module configured to perform a first stage of chemical mechanical polishing on a target wafer; a polishing end detection module configured to stop the first stage of chemical mechanical polishing when a surface thickness of the target wafer reaches a target endpoint thickness, the target endpoint thickness being determined based on a metal line density corresponding to the target wafer; and a second polishing execution module configured to perform a second stage of chemical mechanical polishing on the target wafer, a downforce of the first stage being greater than a downforce of the second stage.

10. A chemical mechanical polishing apparatus characterized by comprising: The chemical mechanical polishing device comprises a polishing head, a polishing pad, and a controller, the controller comprising a memory and a processor, the memory storing a computer program, and the processor being configured to execute the computer program to perform the steps of the method according to any one of claims 1-8.

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