Metal filling groove structure and preparation method thereof

Abstract

According to the metal filling groove structure and the preparation method thereof, the insulating film layer is arranged between the first metal layer and the second metal layer, the second metal layer is ground firstly in the CMP technology process of the metal filling groove by adopting an eddy current sensor, and due to the insulating effect of the insulating film layer, the first metal layer is ground, and the second metal layer is ground; turbine current noise generated by the first metal layer in the groove can be shielded, and the Endpoint end point grabbing accuracy of grinding of the second metal layer is improved. Meanwhile, particularly, when the first metal layer on the surface of the wafer is ground, due to the insulation effect of the insulation film layer, the lowest point of the insulation film layer in the groove area is located at the position of-500 nm to 500 nm at the top of the groove, and therefore the grinding efficiency of the first metal layer on the surface of the wafer is improved. The influence of turbine current noise generated by the first metal layer in the groove on turbine current during grinding of the first metal layer on the surface of the wafer can be effectively shielded, and the Endpoint end point grabbing accuracy is improved; in addition, turbine current signals can be integrally improved, and the CLC and RTPC functions for automatically adjusting the uniformity of the surface of the wafer are enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a metal-filled groove structure and a preparation method thereof. Background Art

[0002] The integrated circuit (IC) industry is growing rapidly, and the materials and design technologies are constantly improving, making the circuits of each new generation of products increasingly miniaturized and complex. In the process of IC evolution, the functional density (i.e., the number of components connected per chip area) has generally increased gradually, while the geometric size (i.e., the smallest component or circuit size produced by the process) has gradually decreased. The reduction in size can bring the benefits of increased production efficiency and reduced costs, but it also increases the complexity of IC technology. The manufacturing process of semiconductor devices includes many processes, such as hundreds of processes that must be performed on a wafer to complete the production of integrated circuits. These processes include depositing dielectric and conductor materials on the wafer, forming circuit patterns through photolithography, etching and development, and usually also include grinding operations to make the surface flat. Commonly used grinding operations such as chemical mechanical planarization (CMP) process are a very important process in the planarization process. In the current semiconductor manufacturing process, CMP process is used in many cases, such as silicon oxide polishing in shallow trench isolation (STI), silicon oxide polishing in local interconnect (LI), silicon oxide polishing in interlayer dielectric (ILD) and metal interconnect line polishing in metal interconnect process.

[0003] The polishing device for performing the CMP process generally comprises: a polishing table supporting a polishing pad, and a wafer holding mechanism called a top ring or a polishing head for holding the wafer. The polishing device supplies polishing liquid to the polishing pad from a polishing liquid supply nozzle, and presses the wafer against the surface (polishing surface) of the polishing pad at a predetermined pressure. At this time, the polishing table and the wafer holding mechanism are rotated so that the wafer and the polishing surface are in sliding contact, thereby polishing the surface of the wafer into a flat and mirror-like surface.

[0004] Taking the copper metal chemical mechanical polishing process as an example, in the preparation process of copper metal connection through holes, a deep well type deep groove is generally formed in the oxide layer, and then metal copper is filled in the deep well type deep groove. During the filling process, the surface of the oxide layer will also be deposited with metal copper; at this time, the metal copper on the surface of the oxide layer needs to be removed through the metal copper chemical mechanical polishing process, and only the metal copper in the deep well type deep groove is retained as the metal connection. In the existing metal chemical polishing process, the eddy current sensor (Eddy Current Monitor of Resistance, RECM) is generally used to detect the eddy current capture end point (Endpoint) and adjust the uniformity (uniformity) of the wafer surface. However, the existing RECM detection has a large fluctuation in the Endpoint curve during the CMP process of trench metal filling, such as Figure 1 As shown, the accuracy of Endpoint detection, closed loop control (CLC) or real-time process control (RTPC) during the grinding process is affected, resulting in metal residues on the wafer surface, reducing the uniformity of wafer surface grinding, and this phenomenon is particularly evident in the CMP process of deep and wide grooves. Summary of the invention

[0005] In view of the shortcomings of the prior art mentioned above, the purpose of the present invention is to provide a metal-filled groove structure and a preparation method thereof, so as to solve the problem that in the prior art, the Endpoint curve fluctuates greatly during the CMP process of the metal-filled groove using an eddy current sensor, which affects the accuracy of Endpoint detection during the grinding process, closed loop control (CLC) or real time process control (RTPC), resulting in metal residues on the wafer surface and reducing the uniformity of wafer surface grinding.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a method for preparing a metal-filled trench structure, the preparation method comprising:

[0007] Providing a wafer, wherein a groove is formed on the wafer;

[0008] A stacked film structure is formed on the wafer and in the groove, and a part of the film layer of the stacked film structure fills the groove; wherein the stacked film structure comprises in sequence: a first metal layer, which fills the groove and the wafer, and is in a concave shape in the groove area and the wafer area adjacent thereto; an insulating film layer, which is deposited on the surface of the first metal layer, and the lowest point of the insulating film layer in the groove area is located at a position of -500nm to 500nm from the top of the groove; a second metal layer of the same nature as the first metal layer, which is deposited on the insulating film layer, and the first metal layer, the insulating film layer and the second metal layer are conformally nested in sequence;

[0009] causing an eddy current sensor disposed inside the grinding table to rotate together with the grinding table;

[0010] The wafer formed with the laminated film structure is pressed against the polishing pad on the rotating polishing table by a polishing head to polish the laminated film structure on the surface of the wafer, wherein the polishing process includes three steps: a first step, grinding the second metal layer, and performing a first polishing endpoint detection on the completion of polishing the second metal layer by the eddy current sensor; a second step, grinding the insulating film layer and the first metal layer, and performing a second polishing endpoint detection on the completion of polishing the first metal layer by the eddy current sensor; and a third step, grinding the wafer and the groove for a preset time so that the groove depth reaches a preset requirement.

[0011] Optionally, the groove has a depth of 150 nm to 5000 nm and a width of 150 nm to 5000 nm, both inclusive.

[0012] Optionally, the stacked film structure also includes: a first adhesion layer and a second adhesion layer; wherein the first adhesion layer is deposited on the groove surface and the wafer surface of the wafer and is located below the first metal layer, and the second adhesion layer is deposited on the insulating film layer surface and is located below the second metal layer.

[0013] Furthermore, the first metal layer and the second metal layer are formed by an electroplating process, the insulating film layer is formed by a chemical vapor deposition process, and the first adhesion layer and the second adhesion layer are formed by a physical vapor deposition process.

[0014] Furthermore, the material of the first adhesion layer and the second adhesion layer is at least one of tantalum and tantalum nitride, or at least one of titanium and titanium nitride.

[0015] Further, in the first step of the grinding process, the second adhesion layer serves as a grinding end point for grinding the second metal layer, and in the second step of the grinding process, the first adhesion layer serves as a grinding end point for grinding the first metal layer.

[0016] Optionally, the materials of the first metal layer and the second metal layer are metal materials used for semiconductor wiring.

[0017] Furthermore, the first metal layer and the second metal layer are made of copper, cobalt, tungsten or aluminum.

[0018] Furthermore, the material of the insulating film layer is at least one of SiCN, SiCO, SiN and SiO2, and the thickness of the insulating film layer is 5nm to 500nm, including end points.

[0019] The present invention also provides a metal-filled trench structure, which is prepared by using any one of the above methods for preparing a metal-filled trench structure.

[0020] As described above, the metal-filled groove structure and preparation method thereof of the present invention, by setting an insulating film layer between the first metal layer and the second metal layer, when the second metal layer is first ground in the CMP process of the metal-filled groove using an eddy current sensor, the insulating effect of the insulating film layer can shield the turbine current noise generated by the first metal layer in the groove, reduce the turbine current noise during the grinding of the second metal layer, and improve the accuracy of the Endpoint capture of the grinding of the second metal layer; at the same time, especially when the first metal layer on the surface of the wafer is ground, due to the insulating effect of the insulating film layer, and the lowest point of the insulating film layer in the groove area is located at a position of -500nm to 500nm from the top of the groove, the turbine current noise generated by the first metal layer in the groove can be effectively shielded from the turbine current when the first metal layer on the surface of the wafer is ground, effectively reducing the fluctuation of the Endpoint curve and improving the accuracy of the Endpoint capture; furthermore, by reducing the turbine current noise generated by the first metal layer in the groove, the turbine current signal can be improved as a whole, the CLC and RTPC functions of automatically adjusting the uniformity of the wafer surface can be enhanced, and the uniformity of the wafer surface grinding can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The diagram shows an endpoint detection curve during the CMP process of metal-filled trenches using an existing eddy current sensor.

[0022] Figure 2 It is a schematic cross-sectional structure diagram of a stacked film structure for filling a trench according to the present invention.

[0023] Figure 3 The diagram shows the positional relationship between the insulating film layer and the top of the trench in the stacked film structure for filling the trench of the present invention.

[0024] Figures 4 to 7The schematic diagram of the cross-sectional structure of each step of the grinding process in the CMP process method of the stacked film structure filling the groove of the present invention is shown.

[0025] Figure 8 It is a schematic diagram of an endpoint detection curve during a CMP process of a metal-filled trench after adopting the stacked film structure for filling the trench of the present invention.

[0026] Component number description

[0027] 10 Wafer

[0028] 11 Groove

[0029] 12 First Adhesion Layer

[0030] 13. First Metal Layer

[0031] 14 Insulation film layer

[0032] 15 Second adhesive layer

[0033] 16 Second Metal Layer DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] See also Figures 2 to 8 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0036] As described in the background technology, the existing RECM detection has a large fluctuation of the Endpoint curve during the CMP process of metal filling in the groove. The inventors have found through research that the reason for this problem may be that: during the CMP process of metal-filled grooves, the metal filled in the groove will also generate a turbine current, and the wider and / or deeper the groove is, the more metal is filled, and the greater the turbine current generated. This signal will affect the RECM signal, increase the noise of the turbine current signal, cause the Endpoint curve to fluctuate, and reduce the accuracy of the Endpoint endpoint capture. Moreover, when the groove is larger and / or deeper, the turbine current generated by the metal filled in the groove is also greater, thereby causing the noise of the turbine current signal to be greater. Therefore, this phenomenon is more obvious during the CMP process of deep and wide grooves.

[0037] Based on the above understanding, Figure 2 and Figure 7 As shown, this embodiment provides a method for preparing a metal-filled trench structure, the preparation method comprising:

[0038] S1, such as Figure 2 As shown, a wafer 10 is provided, and a groove 11 is formed on the wafer 10 .

[0039] S2. A laminated film structure is formed on the wafer 10 and in the groove 11, and a part of the film layer of the laminated film structure fills the groove 11; wherein the laminated film structure comprises in sequence: a first metal layer 13, which is filled in the groove 11 and on the wafer 10, and is in a concave shape in the groove area and the adjacent wafer area. It should be noted that the concave shape of the first metal layer 13 in the groove area and the adjacent wafer area is a natural form formed based on all existing slot filling processes. The depth of the concave shape and the size of the concave shape are determined by the specific slot filling process used and the corresponding process parameters, etc., and no excessive restrictions are made here; an insulating film layer 14, which is deposited on the surface of the first metal layer 13, such as Figure 3 As shown, the insulating film layer 14 is located at the lowest point of the groove area at a position of -500nm to 500nm from the top of the groove; the second metal layer 16, which is homogeneous with the first metal layer 13, is deposited on the insulating film layer 14, and the first metal layer 13, the insulating film layer 14 and the second metal layer 16 are conformally nested in sequence, that is, the surface morphology of the insulating film layer 14 and the second metal layer 16 is maintained consistent with the surface morphology of the first metal layer 13, which is also a natural form formed based on all existing deposition (including electroplating) processes.

[0040] S3. The eddy current sensor disposed inside the grinding table is rotated together with the grinding table.

[0041] S4, such as Figures 4 to 7 As shown, the wafer is pressed against the grinding pad on the rotating grinding table by a grinding head to grind the laminated film structure on the surface of the wafer, wherein the grinding process includes three steps: a first step, grinding the second metal layer 16, and performing a first grinding endpoint detection on the end of grinding the second metal layer 16 by the eddy current sensor; a second step, grinding the insulating film layer 14 and the first metal layer 13, and performing a second grinding endpoint detection on the end of grinding the first metal layer 13 by the eddy current sensor; a third step, grinding the wafer 10 and the groove 11 for a preset time so that the groove depth reaches a preset requirement.

[0042] The preparation method of the metal-filled groove structure of the present embodiment is to set an insulating film layer 14 between the first metal layer 13 and the second metal layer 16. In the process of grinding the metal-filled groove using an eddy current sensor (referred to as CMP), when the second metal layer 16 is first ground, due to the insulating effect of the insulating film layer 14, the turbine current noise generated by the first metal layer 13 in the groove can be shielded, the turbine current noise during the grinding of the second metal layer 16 can be reduced, and the accuracy of capturing the Endpoint of the grinding of the second metal layer 16 can be improved; at the same time, especially when the first metal layer 13 on the surface of the wafer is ground, due to the insulating effect of the insulating film layer 14, and the lowest point of the insulating film layer 14 in the groove area is located at a position of -500nm to 500nm from the top of the groove, the influence of the turbine current noise generated by the first metal layer 13 in the groove on the turbine current during the grinding of the first metal layer 13 on the surface of the wafer can be effectively shielded, the fluctuation of the Endpoint curve can be effectively reduced, and the accuracy of capturing the Endpoint can be improved, such as Figure 8 As shown; furthermore, by reducing the turbine current noise generated by the first metal layer 13 in the groove, the turbine current signal can be improved as a whole, the CLC and RTPC functions of automatically adjusting the uniformity of the wafer surface can be enhanced, and the uniformity of the wafer surface grinding can be improved.

[0043] As is known, the number of grooves 11 on the wafer 10 can be set according to actual needs, generally more than one. In the diagram of this embodiment, only one groove is shown for ease of understanding, but this number cannot be used as a limitation on the scope of protection of the present invention. In addition, the wafer 10 here refers to a wafer that needs to undergo a CMP process at any stage in the semiconductor process, and some other device structures may be formed therein, which is determined specifically according to the process stage and different semiconductor structures, and is not specifically limited here.

[0044] As described above, the stacked film structure of this embodiment has a better improvement effect in the CMP process for wider and deeper trenches. Based on the depth and width requirements of the existing semiconductor process for the trench, the depth of the trench 11 is selected to be 150nm to 5000nm, and the width is 150nm to 5000nm, including the end values, which has a significant improvement effect on the CMP process. However, based on the above principle, it can be seen that if the depth and width of the trench are required to be greater in the subsequent process, the stacked film structure of this embodiment can be better used for the CMP process.

[0045] Generally, in order to improve the adhesion between metal and insulating materials, an adhesion layer is formed between the two. Figure 2 As shown, a first adhesion layer 12 is deposited on the surface of the groove 11 of the wafer 10 and the surface of the wafer 10, and the first adhesion layer 12 is located below the first metal layer 13; a second adhesion layer 15 is deposited on the surface of the insulating layer 14, and the second adhesion layer 15 is located below the second metal layer 16. In addition, the first adhesion layer 12 and the second adhesion layer 15 are conformally nested in the laminated film structure with the first metal layer 13, the insulating film layer 14 and the second metal layer 16. Preferably, the first metal layer 13 and the second metal layer 16 are formed by electroplating, the insulating film layer 14 is formed by chemical vapor deposition, and the first adhesion layer 12 and the second adhesion layer 15 are formed by physical vapor deposition.

[0046] The materials of the first metal layer 13 and the second metal layer 16 are selected from metal materials suitable for filling the trenches. Currently, the function of trench filling is more to achieve electrical connection, that is, to form semiconductor electrical connection lines. Based on this function, the material suitable for semiconductor electrical connection lines can be selected from metal materials with good electrical conductivity and stable chemical properties, such as copper, cobalt, tungsten or aluminum, and the commonly used material is copper.

[0047] The first adhesion layer 12 and the second adhesion layer 15 mainly play an adhesion role, so that the metal material formed thereon can be firmly adhered. The material is generally selected as at least one of tantalum or tantalum nitride, or at least one of titanium or titanium nitride. In some specific cases, the selection of the adhesion layer material will also play a diffusion barrier role according to the properties of the metal layer material. For example, when the material of the first metal layer 13 and the second metal layer 16 is selected as copper material, the material of the first adhesion layer 12 and the second adhesion layer 15 is selected as a mixed material layer of tantalum and tantalum nitride, which can make the copper material adhere better and also play a certain barrier role to prevent the easily diffusible copper particles from diffusing into the wafer material where the groove is located and the insulating film layer 14. Based on this consideration, when the material of the first metal layer 13 and the second metal layer 16 is selected as tungsten material, the material of the first adhesion layer 12 and the second adhesion layer 15 is preferably selected as a mixed material layer of titanium and titanium nitride.

[0048] The material of the insulating film layer 14 is generally selected to be an insulating material with good insulating properties, such as at least one of SiCN, SiCO, SiN and SiO2, etc. When the material of the first metal layer 13 and the second metal layer 16 is selected to be a copper material that is easy to diffuse, preferably, the material of the insulating film layer 14 is selected to be SiCN, which can not only play an insulating role, but also further block the diffusion of copper particles, thereby avoiding the influence of the turbo current noise generated by the first metal layer 13 in the groove during the CMP grinding of the second metal layer 16 due to the diffusion of copper particles on the accuracy of the Endpoint capture.

[0049] As an example, the thickness of the insulating film layer 14 is generally selected to be 5 nm to 500 nm, including end points.

[0050] As another example, the thickness of the first adhesive layer 12 and the second adhesive layer 15 is generally several tens of

[0051] The grinding device for CMP process generally includes: a grinding table, a grinding pad, a grinding head, a driving device and a grinding liquid supply system; the grinding table supports the grinding pad, and a dresser is also provided on the grinding pad to dress the grinding pad, and the wafer is fixed on the grinding head; when in use, the driving device drives the grinding table to rotate, and presses the grinding head toward the grinding pad to achieve grinding of the wafer surface. During grinding, the grinding liquid supply system supplies grinding liquid or slurry to the grinding pad, and performs chemical grinding and / or physical and mechanical grinding on the wafer according to different requirements. At this time, the eddy current sensor is set inside the grinding table, and when the grinding table rotates, the eddy current sensor also rotates with the grinding table. Since the grinding table drives the grinding pad to rotate and the wafer is also rotating during the grinding process, the eddy current sensor can detect the current on the entire wafer surface and obtain the Endpoint detection signal accordingly.

[0052] Preferably, when the stacked film structure for filling the groove further includes the first adhesion layer 12 and the second adhesion layer 15, in S4, the grinding process includes three steps specifically:

[0053] The first step, such as Figure 4 As shown, the second metal layer 16 is ground, and the eddy current sensor is used to perform a first grinding endpoint detection on the end of grinding the second metal layer 16. Here, the eddy current sensor detects the second adhesion layer 15 as the grinding endpoint through the change of current. Since CMP grinding is a process of flattening the surface of the wafer, when performing this step, after the second metal layer 16 on the surface of the wafer is ground, the second metal layer 16 in the inner recess above the groove will be partially retained, as shown in FIG. Figure 4 As shown, in addition, the method generally used for grinding the second metal layer 16 is mainly chemical grinding, that is, by supplying abrasive particles that can react with the second metal layer 16 to the grinding pad, making it react with the second metal layer 16, and washing away the reactants by grinding.

[0054] The second step is to grind the second adhesion layer 15, the insulating film layer 14 and the first metal layer 13, and perform a second grinding endpoint detection on the grinding end of the first metal layer 13 through the eddy current sensor. Here, the eddy current sensor detects the first adhesion layer 12 as the grinding endpoint through the change of current. It should be noted that when performing this step, the second metal layer 16 left in the inner recessed part in the first step should also be ground and removed, and the grinding method is mainly chemical grinding, while the grinding of the second adhesion layer 15 and the insulating film layer 14 is mainly physical and mechanical grinding, and the grinding of the first metal layer 13 is mainly chemical grinding. The specific process is: adding particles that can chemically react with the first metal layer 13 and the second metal layer 16 to the grinding liquid, and adding grinding particles that play a physical and mechanical role at the same time, the chemically reactive particles can grind away the first metal layer 13 and the second metal layer 16 by chemical action, and the grinding particles that play a physical and mechanical role can grind away the second adhesion layer 15 and the insulating film layer 14, thereby obtaining a wafer with a smooth surface, such as Figure 5 and Figure 6 As shown, Figure 5 The structure in FIG. 1 is a structure obtained after the lowest point of the insulating film layer 14 is formed outside the groove and polished. Figure 6 The structure in is a structure obtained after the lowest point of the insulating film layer 14 is formed in the groove and polished;

[0055] The third step is to grind the first adhesion layer 12, the wafer and the groove for a preset time so that the groove depth reaches the preset requirement; in this step, it is necessary to first grind and remove the first adhesion layer 12 on the wafer surface, and on this basis, grind the wafer surface and the groove surface for a preset time so that the groove depth reaches the preset requirement, and the preset grinding time and the preset groove depth requirement are set according to actual needs; in addition, the principle for grinding the first adhesion layer 12, the wafer surface and the groove surface is that metal materials are mainly ground by chemical action, and insulating materials are mainly ground by physical and mechanical action. In this grinding process, the proportion parameters of different particles in the grinding liquid are adjusted to make the grinding rates of different areas of the wafer surface consistent, so as to achieve the effect of obtaining a smooth surface. This is a conventional adjustment method in this field, which is selected and set according to specific circumstances, and is not excessively restricted here.

[0056] Based on the above method for preparing a metal-filled trench structure, this embodiment further provides a metal-filled trench structure prepared by the above method.

[0057] In summary, the present invention provides a metal-filled groove structure and a preparation method thereof. By setting an insulating film layer between a first metal layer and a second metal layer, when the second metal layer is first ground using an eddy current sensor for a CMP process on the metal-filled groove, due to the insulating effect of the insulating film layer, the turbine current noise generated by the first metal layer in the groove can be shielded, the turbine current noise during the grinding of the second metal layer can be reduced, and the accuracy of capturing the Endpoint of the grinding of the second metal layer can be improved; at the same time, especially when the first metal layer on the surface of the wafer is ground, due to the insulating effect of the insulating film layer, and the lowest point of the insulating film layer in the groove area is located at a position of -500nm to 500nm from the top of the groove, the influence of the turbine current noise generated by the first metal layer in the groove on the turbine current during the grinding of the first metal layer on the surface of the wafer can be effectively shielded, the fluctuation of the Endpoint curve can be effectively reduced, and the accuracy of capturing the Endpoint can be improved; furthermore, by reducing the turbine current noise generated by the first metal layer in the groove, the turbine current signal can be improved as a whole, the CLC and RTPC functions of automatically adjusting the uniformity of the wafer surface can be enhanced, and the uniformity of the wafer surface grinding can be improved. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a metal-filled trench structure, characterized in that: The preparation method comprises: Providing a wafer, wherein a groove is formed on the wafer; A stacked film structure is formed on the wafer and in the groove, and a part of the film layer of the stacked film structure fills the groove; wherein the stacked film structure comprises in sequence: a first metal layer, which fills the groove and the wafer, and is in a concave shape in the groove area and the wafer area adjacent thereto; an insulating film layer, which is deposited on the surface of the first metal layer, and the lowest point of the insulating film layer in the groove area is located at a position of -500nm to 500nm from the top of the groove; a second metal layer of the same nature as the first metal layer, which is deposited on the insulating film layer, and the first metal layer, the insulating film layer and the second metal layer are conformally nested in sequence; causing an eddy current sensor disposed inside the grinding table to rotate together with the grinding table; The wafer formed with the laminated film structure is pressed against the polishing pad on the rotating polishing table by a polishing head to polish the laminated film structure on the surface of the wafer, wherein the polishing process includes three steps: a first step, grinding the second metal layer, and performing a first polishing endpoint detection on the completion of polishing the second metal layer by the eddy current sensor; a second step, grinding the insulating film layer and the first metal layer, and performing a second polishing endpoint detection on the completion of polishing the first metal layer by the eddy current sensor; and a third step, grinding the wafer and the groove for a preset time so that the groove depth reaches a preset requirement.

2. The method for preparing a metal-filled trench structure according to claim 1, characterized in that: The groove has a depth of 150nm to 5000nm and a width of 150nm to 5000nm, both inclusive.

3. The method for preparing a metal-filled trench structure according to claim 1, characterized in that: The stacked film structure also includes: a first adhesion layer and a second adhesion layer; wherein the first adhesion layer is deposited on the groove surface and the wafer surface of the wafer and is located below the first metal layer, and the second adhesion layer is deposited on the insulating film layer surface and is located below the second metal layer.

4. The method for preparing a metal-filled trench structure according to claim 3, characterized in that: The first metal layer and the second metal layer are formed by an electroplating process, the insulating film layer is formed by a chemical vapor deposition process, and the first adhesion layer and the second adhesion layer are formed by a physical vapor deposition process.

5. The method for preparing a metal-filled trench structure according to claim 3, characterized in that: The material of the first adhesion layer and the second adhesion layer is at least one of tantalum and tantalum nitride, or at least one of titanium and titanium nitride.

6. The method for preparing a metal-filled trench structure according to claim 3, characterized in that: In the first step of the grinding process, the second adhesion layer serves as a grinding end point for grinding the second metal layer, and in the second step of the grinding process, the first adhesion layer serves as a grinding end point for grinding the first metal layer.

7. The method for preparing a metal-filled trench structure according to claim 1, characterized in that: The materials of the first metal layer and the second metal layer are metal materials used for semiconductor wiring.

8. The method for preparing a metal-filled trench structure according to claim 7, characterized in that: The first metal layer and the second metal layer are made of copper, cobalt, tungsten or aluminum.

9. The method for preparing a metal-filled trench structure according to any one of claims 1 to 8, characterized in that: The material of the insulating film layer is at least one of SiCN, SiCO, SiN and SiO2, and the thickness of the insulating film layer is 5nm to 500nm, including end points.

10. A metal-filled trench structure, characterized in that: The metal-filled trench structure is prepared by the method for preparing the metal-filled trench structure as claimed in any one of claims 1 to 9.

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