End point detection structure and end point detection device

Abstract

The application provides a polishing endpoint detection structure and a polishing endpoint detection device. The polishing endpoint detection structure comprises a magnetic structure arranged above a structure to be detected, and the magnetic structure is a single magnetic material layer or a composite magnetic material layer. A reflected signal formed by emitting linearly polarized light to the surface of the single magnetic material layer or the composite magnetic material layer and then reflecting the linearly polarized light by the magnetic structure is used to determine the polishing endpoint. The polishing endpoint detection structure can improve the accuracy of the polishing endpoint determination.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a grinding endpoint detection structure and a grinding endpoint detection device. Background Technology

[0002] With the development of semiconductor chip technology and the advancement of Moore's Law, the feature size of semiconductor devices has moved from the micrometer level to the nanometer level, and the number of film layers continues to increase. The formation and patterning of each film layer requires the surface of the previous film layer or wafer to achieve atomic-level flatness. In semiconductor chip manufacturing processes, chemical mechanical polishing (CMP) is a key surface planarization technology that runs through critical nodes of both the front end of line (FEOL) and back end of line (BEOL).

[0003] Chemical mechanical polishing (CMP) removes excess material through the synergistic action of a slurry and a polishing pad, enabling high-precision surface finishing. CMP requires precise control of the polishing endpoint to prevent under-polishing or over-polishing, ensuring device yield and performance. Existing methods for determining the polishing endpoint (e.g., conventional optical EPD (Endpoint Detection) curves) suffer from drawbacks such as unsatisfactory detection results and are not applicable to various testing scenarios.

[0004] Therefore, a new solution is needed to effectively determine the grinding endpoint of semiconductor devices. Summary of the Invention

[0005] This application provides a grinding endpoint detection structure and a grinding endpoint detection device to improve the accuracy of grinding endpoint determination.

[0006] In a first aspect, embodiments of this application provide a grinding endpoint detection structure, applied to a structure to be tested, the grinding endpoint detection structure comprising:

[0007] A magnetic structure is disposed at least above the structure to be tested, wherein the magnetic structure is a single magnetic material layer or a composite magnetic material layer;

[0008] The grinding endpoint is determined by the reflected signal formed after linearly polarized light is emitted onto the surface of the single magnetic material layer or the composite magnetic material layer and reflected by the magnetic structure.

[0009] In one possible implementation, the composite magnetic material layer includes a magnetic material layer and a protective layer located above the magnetic material layer.

[0010] In one possible implementation, the single magnetic material layer fills the via or trench and extends outside the via or trench, the via or trench being formed in a first dielectric layer above the structure under test;

[0011] The single magnetic material layer is subjected to chemical mechanical polishing, and the polishing ends when the reflected signal disappears. After polishing, the single magnetic material layer located in the through hole or trench is retained to form an interconnect structure.

[0012] In one possible implementation, the structure under test is a magnetic tunnel junction;

[0013] The composite magnetic material layer includes:

[0014] A first magnetic material layer is disposed above the magnetic tunnel junction;

[0015] A first protective layer is disposed above the first magnetic material layer, and a second dielectric layer is also formed above the first protective layer;

[0016] The first magnetic material layer, the first protective layer, and the magnetic tunnel junction are jointly etched together to form the structure.

[0017] The grinding process continues until the first magnetic material layer is exposed, and the grinding endpoint is reached when the reflected signal undergoes a sudden change. This process involves a first chemical mechanical grinding of the second dielectric layer and the first protective layer until the first magnetic material layer is exposed.

[0018] In one possible implementation, the composite magnetic material layer further includes:

[0019] A second magnetic material layer is disposed above the second dielectric layer;

[0020] A second protective layer is disposed above the second magnetic material layer. The second protective layer and the second magnetic material layer are jointly etched together, and a third dielectric layer is filled around the second protective layer and the second magnetic material layer.

[0021] The third dielectric layer and the second protective layer are subjected to a second chemical mechanical polishing until the second magnetic material layer is exposed. The polishing endpoint is reached when the reflected signal undergoes a sudden change.

[0022] In one possible implementation, the structure under test is a magnetic tunnel junction of the out-of-plane, field-free, vertical magnetization reversal type, and the magnetic material layer in the single magnetic material layer or the composite magnetic material layer assists the magnetic tunnel junction in achieving field-free reversal.

[0023] In one possible implementation, the structure under test is a magnetic tunnel junction, and the sides and top surface of the magnetic tunnel junction are covered with a fourth dielectric layer.

[0024] The single magnetic material layer covers the surface of the fourth dielectric layer, and the single magnetic material layer is covered with a fifth dielectric layer.

[0025] The grinding process ends when the reflected signal disappears after the first chemical mechanical grinding of the fourth dielectric layer, the fifth dielectric layer, and the single magnetic material layer.

[0026] In one possible implementation, it also includes:

[0027] A sixth dielectric layer covers the fourth dielectric layer, the fifth dielectric layer, and the single magnetic material layer, and a groove is formed in the sixth dielectric layer;

[0028] A first metal layer fills the groove and covers the top surface of the sixth dielectric layer;

[0029] The first metal layer is subjected to a second chemical mechanical polishing, and the end point of the polishing is determined by detecting eddy currents.

[0030] The single magnetic material layer shields the magnetic field generated by eddy current detection to protect the magnetic tunnel junction.

[0031] In one possible implementation, the magnetic field generated by the magnetic material layer in the single magnetic material layer or the composite magnetic material layer cancels out the stray magnetic field generated by the structure under test; and / or,

[0032] The grinding endpoint detection structure further includes a monitoring structure, which is disposed in the same layer as the structure under test and is correspondingly provided with the single magnetic material layer or the composite magnetic material layer. The critical dimension of the monitoring structure is larger than the critical dimension of the structure under test to ensure the intensity of the reflected signal.

[0033] The grinding endpoint detection structure provided in this application provides a magnetic structure above the structure to be tested. By emitting linearly polarized light into the magnetic structure and determining the grinding endpoint based on the reflected signal formed after reflection by the magnetic structure, the modulation effect of the magnetic structure on the reflected signal can enhance the recognizability of the endpoint detection signal. This reduces the adverse effects of weak signal caused by relying solely on reflectivity differences and susceptibility to surface state disturbances, thereby improving the sensitivity and accuracy of grinding endpoint determination and enhancing the stability of the chemical mechanical grinding process.

[0034] Secondly, embodiments of this application provide a grinding endpoint detection device, comprising:

[0035] Transmitter, emits a beam of light;

[0036] A reflector, opposite to the emitter, is used to reflect the light beam onto the grinding endpoint detection structure;

[0037] A polarizer polarizer is disposed between the reflector and the grinding endpoint detection structure to convert the light beam into linearly polarized light;

[0038] The analyzer polarizer is opposite to the grinding end point detection structure, allowing the reflected signal formed after reflection by the grinding end point detection structure to pass through. The polarization direction of the analyzer polarizer is orthogonal to that of the polarizer polarizer and has a deflection angle.

[0039] The detector, positioned opposite the polarizer of the analyzer, detects the reflected signal.

[0040] The grinding endpoint detection device provided in this application employs an optical path relationship formed by a transmitter, a reflector, a polarizer, a grinding endpoint detection structure, an analyzer, and a detector. The determination of the grinding endpoint no longer relies solely on differences in ordinary reflection strength, but instead utilizes the change in polarization response of the grinding endpoint detection structure as an indicator of the grinding endpoint. By keeping the analyzer polarizer orthogonal to the polarizer polarizer and setting a deflection angle, subtle polarization changes can be selectively identified, making the reflected signal more suitable for real-time output during chemical mechanical polishing, thereby achieving accurate determination of the grinding endpoint. Attached Figure Description

[0041] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0042] Figure 1 A schematic diagram of the first dielectric layer after its formation in one embodiment of this application is provided;

[0043] Figure 2 This is a schematic diagram of a through-hole formed in one embodiment of the present application.

[0044] Figure 3 This application provides a schematic diagram of an embodiment after forming a single magnetic material layer;

[0045] Figure 4 A schematic diagram of the interconnect structure formed in one embodiment of this application is provided;

[0046] Figure 5 This is a schematic diagram of the magnetic tunnel junction after formation in another embodiment of this application.

[0047] Figure 6 This is a schematic diagram of the first dielectric layer after its formation in another embodiment of this application.

[0048] Figure 7 This is a schematic diagram showing the through hole formed in another embodiment of this application.

[0049] Figure 8 A schematic diagram of another embodiment of this application after forming a single magnetic material layer is provided;

[0050] Figure 9 A schematic diagram of the interconnect structure formed in another embodiment provided in this application;

[0051] Figure 10 A schematic diagram showing the formation of the first magnetic material layer and the first protective layer in another embodiment provided for the present application;

[0052] Figure 11 This is a schematic diagram of the magnetic tunnel junction formed in another embodiment of the present application.

[0053] Figure 12 This is a schematic diagram of the second dielectric layer after its formation in another embodiment of the present application.

[0054] Figure 13 A schematic diagram of the first chemical mechanical grinding process in another embodiment provided in this application;

[0055] Figure 14 A schematic diagram of the second magnetic material layer and the second protective layer after formation in another embodiment provided for the present application;

[0056] Figure 15 A schematic diagram of the second magnetic material layer and the second protective layer after etching in another embodiment of this application;

[0057] Figure 16 A schematic diagram of the third dielectric layer after its formation in another embodiment provided in this application;

[0058] Figure 17 A schematic diagram of the second chemical mechanical grinding process in yet another embodiment provided in this application;

[0059] Figure 18 A schematic diagram showing the formation of the first magnetic material layer and the first protective layer in another embodiment provided for the present application;

[0060] Figure 19 This is a schematic diagram of the magnetic tunnel junction formed in another embodiment of the present application.

[0061] Figure 20 A schematic diagram of a single magnetic material layer after being formed in another embodiment provided in this application;

[0062] Figure 21 This is a schematic diagram showing the formation of the fourth dielectric layer in another embodiment provided in this application.

[0063] Figure 22 A schematic diagram of the first chemical mechanical grinding process in another embodiment provided in this application;

[0064] Figure 23 This is a schematic diagram showing the groove formed in another embodiment of the present application.

[0065] Figure 24 A schematic diagram of the first metal layer after its formation in another embodiment provided in this application;

[0066] Figure 25 A schematic diagram of the second chemical mechanical grinding process in another embodiment provided in this application;

[0067] Figure 26 This is a schematic diagram of the grinding endpoint detection device provided in an embodiment of this application.

[0068] Explanation of reference numerals in the attached figures:

[0069] 10-Substrate;

[0070] 20 - Single magnetic material layer; 21 - Interconnection structure;

[0071] 31-First magnetic material layer; 31a-First magnetic material; 32-First protective layer; 32a-First protective material; 33-Second magnetic material layer; 33a-Second magnetic material; 34-Second protective layer; 34a-Second protective material;

[0072] 41-First dielectric layer; 41a-Through hole; 42-Second dielectric layer; 43-Third dielectric layer; 44-Fourth dielectric layer; 45-Fifth dielectric layer; 46-Sixth dielectric layer; 46a-Groove;

[0073] 50-Magnetic tunnel junction; 51-Magnetic tunnel junction membrane stack;

[0074] 60 - Bottom electrode; 61 - Bottom electrode material;

[0075] 71-First metal layer; 72-Second metal layer; 73-Third metal layer; 73a-Third metal material; 74-Fourth metal layer; 74a-Fourth metal material; 75-Fifth metal layer; 75a-Fifth metal material;

[0076] 80-Monitoring Structure;

[0077] 91-Emitter; 92-Reflector; 93-Polarizer; 94-Polarizer; 95-Detector; 96-Grinding pad; 97-Wafer; 98-Grinding disc; 99-Optical window.

[0078] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0079] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0080] Chemical mechanical polishing (CMP) is a crucial process affecting the dimensional consistency and electrical and magnetic properties of devices. The endpoint of CMP can be determined using optical detection and eddy current detection. Optical detection involves emitting a light beam onto the film surface and analyzing the interference signal or reflectivity change of the reflected light to measure the remaining film thickness in real time. The endpoint is determined when the remaining film thickness reaches the target value. Eddy current detection uses coils to measure the change in eddy current induced in the film to calculate the remaining film thickness; the endpoint is also determined when the remaining film thickness reaches the target value.

[0081] However, when the difference in reflected light is small, the signal difference at the endpoint is not obvious, making it difficult to accurately determine the grinding endpoint. When the structure under test should not be exposed to a magnetic field, it is difficult to use eddy currents to determine the grinding endpoint. If grinding time is calculated and modified only through a large number of pilot runs without relying on real-time endpoint detection, or if optical detection is used to replace eddy current detection and control polishing time, process stability and productivity will be reduced, and costs and defects will increase.

[0082] Taking the magnetic tunnel junction (MTJ) structure as an example, magnetoresistive random access memory (MRAM) using MTJs is considered the future direction of memory development due to its high speed, low power consumption, and non-volatility. In the fabrication process of a MTJ, after the MTJ film is deposited, the MTJ structure needs to be formed through photolithography and etching. Then, dielectric material is deposited to form a dielectric layer, and the dielectric layer on top of the MTJ structure is smoothed using chemical mechanical polishing.

[0083] However, the difference in reflected light between the MTJ structure and the dielectric layer is small, and the device density is limited, making the ordinary optical EPD (Endpoint Detection) curve insufficiently clear, thus making it difficult to accurately determine the grinding endpoint using optical detection methods. Furthermore, the magnetic field generated by eddy currents affects the performance of the MTJ structure, making it unsuitable for exposure to magnetic fields and hindering the use of eddy current detection for grinding endpoint determination.

[0084] The grinding endpoint detection structure and device provided in this application no longer limit the determination of the grinding endpoint to the difference in material reflectivity, but are based on the magneto-optical Kerr effect. By introducing the optical response of the characteristic reflection signal generated when the magnetic material reflects linearly polarized light, the endpoint identification is based on the signal change of the magnetic structure. Specifically, a magnetic structure is set above the structure to be tested. The magnetic structure adopts a single magnetic material layer or a composite magnetic material layer. During the grinding process, linearly polarized light is emitted to its surface, and the endpoint is determined based on the change of the reflection signal formed after reflection by the magnetic structure.

[0085] By adopting the aforementioned identification path, the endpoint detection is separated from the slight reflectivity differences between the metal and dielectric layers, resulting in a more concentrated detection signal source. This improves the endpoint sensitivity and accuracy during the polishing process of the magnetic storage structure, and enhances processing stability. The magnetic structure can also serve as a magnetic shielding layer for subsequent top electrode CMP processes, enabling the CMP process to utilize eddy currents for grinding endpoint detection and automatic voltage adjustment. Furthermore, the magnetic structure can assist in field-free reversal and shield external magnetic fields.

[0086] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0087] See Figures 1 to 25This application provides a grinding endpoint detection structure, applied to the structure to be tested. The grinding endpoint detection structure includes: a magnetic structure, which is at least disposed above the structure to be tested. The magnetic structure is a single magnetic material layer or a composite magnetic material layer. The grinding endpoint is determined by the reflected signal formed after emitting linearly polarized light onto the surface of the single magnetic material layer or the composite magnetic material layer and reflecting it through the magnetic structure.

[0088] The structure under test is a semiconductor layer monomer or stack that carries the magnetic structure and provides mechanical support and process reference during chemical mechanical polishing. The structure under test can be substrate 10 or device structures on substrate 10 (such as magnetic tunnel junction 50, active structure, gate structure, etc.). Substrate 10 can be a silicon substrate, germanium substrate, silicon-germanium substrate, silicon-on-insulator (SOI) substrate, germanium-on-insulator (GOI) substrate, gallium nitride substrate, or III-V compound semiconductor substrate, etc.

[0089] The magnetic structure is a functional layer, at least above the structure under test, used to interact with linearly polarized light to generate a reflection signal for endpoint detection. It provides a reflective interface with magneto-optical response characteristics during chemical mechanical polishing, allowing the endpoint determination criterion to shift to changes in the reflected signal of the magnetic structure, thus achieving optical endpoint detection based on the magneto-optical Kerr effect. Specifically, when emitted linearly polarized light illuminates the magnetic structure and is reflected, its polarization state is directly affected by the magnetization state of the magnetic structure, changing in the reflected light and forming an interpretable reflection signal. In other words, the magnetic structure modulates the reflected signal, which carries information about the magnetization state of the magnetic structure.

[0090] The magnetic structure is disposed at least on the side of the structure under test facing away from the substrate 10, and can be irradiated by linearly polarized light and exposed or kept exposed during chemical mechanical polishing, so that the endpoint detection signal originates from the magnetic response rather than solely from the reflectivity difference between adjacent materials. For example, the magnetic structure is entirely located above the structure under test; another example is that the magnetic structure is located above the structure under test and extends to the side of the structure under test.

[0091] The magnetic structure can be a single magnetic material layer 20 or a composite magnetic material layer. The single magnetic material layer 20 refers to a continuous film layer formed of a single magnetic material, which can be any one of a cobalt layer, an iron layer, a nickel layer, a cobalt-iron layer, a cobalt-iron-boron layer, a nickel-iron layer (i.e., a permalloy layer), or a cobalt-platinum layer. For example, if the single magnetic material layer 20 is a cobalt layer, using cobalt with low resistivity results in a smaller size reduction effect compared to copper, making it a viable alternative to copper. Furthermore, cobalt has a higher melting point, which is more conducive to reducing electromigration failure caused by atomic diffusion.

[0092] Understandably, copper possesses excellent resistivity and conductivity, making it suitable as an interconnect structure in integrated circuits. However, as feature sizes continue to shrink, the cross-sectional area of ​​copper interconnect structures further decreases, leading to a sharp increase in resistivity and causing serious reliability issues, making it difficult to meet the miniaturization requirements of advanced integrated circuits. Cobalt, on the other hand, exhibits a smaller size reduction effect; that is, its physical and electrical properties do not change significantly as feature sizes continue to decrease. Using cobalt interconnect structures can improve device reliability.

[0093] The composite magnetic material layer may include a magnetic material layer and a protective layer situated on top of it. The magnetic material layer and the protective layer form a stacked structure. The protective layer, in conjunction with the magnetic material layer, creates a sudden change in the reflected signal, serving as the endpoint of the polishing process. The protective layer can also cover and isolate the magnetic material layer, preventing it from being over-removed during chemical mechanical polishing and maintaining stable surface magneto-optical properties. This makes the amplitude and phase changes of the reflected signal more readily correspond to actual layer changes, thereby reducing the interference of surface defects, residual particles, and localized roughness on the detection results and making the determination of the polishing endpoint more stable.

[0094] The magnetic material layer may include at least one of the following: a cobalt layer, an iron layer, a nickel layer, a cobalt-iron layer, a cobalt-iron-boron layer, a nickel-iron layer (i.e., a permalloy layer), or a cobalt-platinum layer. The protective layer may be at least one of the following: a silicon oxide layer, an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a silicon carbide nitride layer. The magnetic material layer and the protective layer may be single layers or stacked layers. For example, the magnetic material layer may be a single cobalt layer, and the protective layer may be a single silicon oxide layer. Another example is a cobalt / nickel-iron / cobalt stack, where the intensity and gradient of the reflected signal are enhanced through the superposition of the magneto-optical Kerr effect of different magnetic materials. The protective layer may be directly deposited on top of the magnetic material layer to form a planar capping layer, or it may be formed as a locally patterned capping layer on top of the magnetic material layer.

[0095] In a first possible embodiment, a single magnetic material layer 20 fills the via 41a or trench and extends to the outside of the via 41a or trench, the via 41a or trench being formed in the first dielectric layer 41 above the structure under test; the single magnetic material layer 20 is chemically and mechanically polished until the reflection signal disappears, and after polishing, the single magnetic material layer 20 located in the via 41a or trench is retained to form an interconnect structure 21.

[0096] like Figure 1 and Figure 2As shown, the first dielectric layer 41 is located on the structure under test, and its material can be an insulating material, such as a low dielectric constant material or a high dielectric constant material. Through-holes 41a or trenches are provided within the first dielectric layer 41, and both through-holes 41a and trenches can penetrate the first dielectric layer 41. Through-holes 41a or trenches can be interlayer vias 41a (such as contact holes) or local interconnect trenches. The shape and size (such as depth and width) of the through-holes 41a or trenches can be set as needed, and this embodiment is not limited in this respect.

[0097] like Figure 2 and Figure 3 As shown, a single magnetic material layer 20 fills the through-hole 41a or trench and extends onto the first dielectric layer 41. The single magnetic material layer 20 is in direct contact with the structure under test and the first dielectric layer 41 or through an interface layer. This portion of the single magnetic material layer 20 outside the through-hole 41a or trench (i.e., on the first dielectric layer 41) is removed during chemical mechanical polishing. When the polished surface approaches the first dielectric layer 41, due to the significant difference in optical reflection characteristics between the single magnetic material layer 20 and the underlying first dielectric layer 41, the reflection signal monitored online gradually weakens and disappears, indicating that the first dielectric layer 41 has been exposed, that is, polished to a position flush with or nearly flush with the first dielectric layer 41. This point can be determined as the polishing endpoint. Figures 2 to 4 As shown, after the chemical mechanical polishing stops, the single magnetic material layer 20 retained inside the through-hole 41a or trench forms an interconnect structure 21 that electrically connects the upper and lower layers. In this way, the endpoint detection and interconnect forming share the same material layer and can maintain process consistency, thereby reducing the impact of over-polishing on the underlying structure under test and improving the stability of interconnect height control.

[0098] In this process, a single magnetic material layer 20 fills the through-hole 41a or trench and extends onto the first dielectric layer 41 outside the through-hole 41a or trench. The single magnetic material layer 20 has a large area and a high intensity of reflected signal, ensuring the endpoint gripping ability without the need for other auxiliary structures, thereby ensuring control over the grinding endpoint. The single magnetic material layer 20 extending onto the first dielectric layer 41 outside the through-hole 41a or trench serves as the stop layer for chemical mechanical polishing.

[0099] In the above embodiments, the structure under test can be a substrate 10, and the interconnect structure 21 is a conductive via or conductive trench formed on the substrate 10 for interlayer metal connection or connection of magnetic tunnel junction 50; the structure under test can also be a magnetic tunnel junction 50, and the interconnect structure 21 is a conductive via or conductive trench formed above the magnetic tunnel junction 50 for external connection of the magnetic tunnel junction 50; the structure under test can also be a transistor, etc., and the interconnect structure 21 is a conductive via or conductive trench connecting interconnect layers for external connection of the active structure, gate structure, etc. of the transistor. The structure under test can also be an interconnect layer, and the interconnect structure 21 is a conductive via or conductive trench connecting adjacent interconnect layers for realizing connection of different interconnect layers.

[0100] As one possible implementation, such as Figures 1 to 4 As shown, the structure under test is substrate 10, which can be bulk silicon or silicon-on-insulator. The grinding process for detecting the end point of the grinding is as follows: a first dielectric layer 41 is formed on substrate 10, and a pattern is etched on the first dielectric layer 41 to form vias 41a or trenches; different functional layers are deposited as needed, including barrier layers, adhesion layers, etc. The barrier layer is used to prevent atomic diffusion, and the adhesion layer is used to enhance the bonding force; a single magnetic material layer 20 (such as a cobalt layer) is formed, which can be filled on the first dielectric layer 41 and in the vias 41a or trenches by chemical vapor deposition, atomic layer deposition, physical vapor deposition, electroplating, etc., and then subjected to high-temperature annealing and an external magnetic field to form magnetic domains in the single magnetic material layer 20, so as to reflect the linearly polarized light hitting the surface of the single magnetic material layer 20; the single magnetic material layer 20 outside the vias 41a or trenches is chemically mechanically ground, and the single magnetic material layer 20 outside the vias 41a or trenches becomes thinner, and the reflected signal gradually disappears, which is the end point of the grinding.

[0101] The polished single magnetic material layer 20 forms an interconnect structure 21. During the polishing process, the interconnect structure 21 is stopped using the magneto-optical Kerr effect during chemical mechanical polishing (CMP). The magneto-optical Kerr effect can be applied to any scenario involving magnetic material via filling. The via filling can refer to the damascus process for copper metal, where magnetic material (such as chemical deposition, physical deposition, or electroplating) is deposited in the via 41a. Subsequently, the magnetic material outside the via 41a is removed by CMP, and this CMP can be stopped using the magneto-optical Kerr effect.

[0102] As another possible implementation, such as Figures 5 to 9As shown, the structure under test is a magnetic tunnel junction 50. The magnetic tunnel junction 50 is a multi-layer stacked structure with a free layer, a barrier layer, and a reference layer. The magnetic tunnel junction 50 is formed on the substrate 10. Existing structures can be used for the magnetic tunnel junction 50, which will not be elaborated here. The grinding process for detecting the structure using the grinding endpoint is as follows: A bottom electrode material (such as tungsten, platinum, or other heavy metals), a magnetic tunnel junction film stack, and a second metal layer 72 (such as tantalum) are sequentially stacked on the substrate 10; the bottom electrode material, the magnetic tunnel junction film stack, and the second metal layer 72 are etched to correspondingly form the bottom electrode 60, the magnetic tunnel junction 50, and the patterned second metal layer 72; a first dielectric layer 41 is formed, covering the bottom electrode 60, the magnetic tunnel junction 50, and the second metal layer 72; the first dielectric layer 41 is thinned by chemical mechanical polishing, and the top surface of the first dielectric layer 41 after polishing is higher than the top surface of the second metal layer 72, without exposing the second metal layer 72. A via 41a or a trench is formed within the first dielectric layer 41, for example, by etching the first dielectric layer 41 to form a via 41a or a trench of a custom shape, exposing the second metal layer 72 within the via 41a or trench; a single magnetic material layer 20 (such as a cobalt layer) is formed, which can be filled on the first dielectric layer 41 and within the via 41a or trench by means of chemical vapor deposition, atomic layer deposition, physical vapor deposition, electroplating, etc.; the single magnetic material layer 20 outside the via 41a or trench is chemically and mechanically polished, and the single magnetic material layer 20 outside the via 41a or trench becomes thinner, and the reflected signal gradually disappears, which is the end point of the polishing.

[0103] The polished single magnetic material layer 20 forms an interconnect structure 21, which serves as the top electrode. During the polishing process, the interconnect structure 21 is held in place using the magneto-optical Kerr effect during chemical mechanical polishing. The single magnetic material layer 20 within the via 41a or trench can also assist in field-free flipping (Type-Z).

[0104] In the second possible embodiment, see Figures 10 to 13 The structure under test is a magnetic tunnel junction 50; the composite magnetic material layer includes: a first magnetic material layer 31, disposed above the magnetic tunnel junction 50; a first protective layer 32, disposed above the first magnetic material layer 31, and a second dielectric layer 42 is also formed above the first protective layer 32; the first magnetic material layer 31, the first protective layer 32 and the magnetic tunnel junction 50 are etched together; the second dielectric layer 42 and the first protective layer 32 are subjected to a first chemical mechanical polishing until the first magnetic material layer 31 is exposed, and the polishing ends when the reflected signal changes abruptly.

[0105] The magnetic tunnel junction 50 is a multilayer stacked structure having a free layer, a barrier layer, and a reference layer. A first magnetic material layer 31 is disposed on the magnetic tunnel junction 50, a first protective layer 32 covers the side of the first magnetic material layer 31 away from the magnetic tunnel junction 50, and a second dielectric layer 42 is formed above the first protective layer 32, covering the first protective layer 32, the first magnetic material layer 31, and the magnetic tunnel junction 50. The first magnetic material layer 31 may include at least one of a cobalt layer, an iron layer, a nickel layer, a cobalt-iron layer, a cobalt-iron-boron layer, a nickel-iron layer (i.e., a permalloy layer), or a cobalt-platinum layer. The first protective layer 32 may be at least one of a silicon oxide layer, an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a silicon carbide nitride layer. The second dielectric layer 42 may be made of an insulating material, such as a low dielectric constant material or a high dielectric constant material. The second dielectric layer 42 and the first protective layer 32 may be made of the same or different materials.

[0106] The first magnetic material layer 31, the first protective layer 32, and the magnetic tunnel junction 50 are etched together, and the three have basically the same shape and size. For example, the outer peripheral surfaces of the first magnetic material layer 31, the first protective layer 32, and the magnetic tunnel junction 50 are flush. The second dielectric layer 42 covers the top surface of the first protective layer 32 and the sides of the first protective layer 32, the first magnetic material layer 31, and the magnetic tunnel junction 50. The second dielectric layer 42 and the first protective layer 32 are removed by a first chemical mechanical polishing. When the polishing surface approaches the first magnetic material layer 31, due to the significant difference in optical reflection characteristics between the first magnetic material layer 31 and the upper first protective layer 32, the reflection signal monitored online changes abruptly, indicating that the first magnetic material layer 31 has been exposed. At this point, the polishing endpoint can be determined. Since the endpoint identification directly corresponds to the exposed interface of the first magnetic material layer 31, the endpoint determination can be correlated with the pattern boundary state above the magnetic tunnel junction 50, ensuring that subsequent processes maintain a consistent top morphology and interlayer alignment, thereby obtaining more stable polishing endpoint control and more consistent device planarization results.

[0107] As one possible implementation, the structure under test is a magnetic tunnel junction 50, the composite magnetic material layer includes a first magnetic material layer 31 and a first protective layer 32, and a second dielectric layer 42 is covered on the composite magnetic material layer. The grinding process for the grinding endpoint detection structure is as follows: A bottom electrode material 61 (such as tungsten, platinum, or other heavy metals), a magnetic tunnel junction film stack 51, a third metal material 73a (such as tantalum), a first magnetic material 31a (such as cobalt, nickel-iron, or other soft magnetic materials), and a first protective material 32a are sequentially stacked on a substrate 10. The bottom electrode material 61, the magnetic tunnel junction film stack 51, the third metal material 73a, the first magnetic material 31a, and the first protective material 32a are etched to form a bottom electrode 60, a magnetic tunnel junction 50, a third metal layer 73, a first magnetic material layer 31, and a first protective layer 32. A second dielectric layer 42 is formed, covering the bottom electrode 60, the magnetic tunnel junction 50, the third metal layer 73, the first magnetic material layer 31, and the first protective layer 32. The second dielectric layer 42 and the first protective layer 32 are subjected to a first chemical mechanical grinding. When grinding reaches the first magnetic material layer 31, due to the magneto-optical Kerr effect, the reflected signal suddenly increases, and this is taken as the grinding endpoint.

[0108] See some possible examples. Figures 14 to 17 The composite magnetic material layer further includes: a second magnetic material layer 33 disposed above the second dielectric layer 42; a second protective layer 34 disposed above the second magnetic material layer 33, wherein the second protective layer 34 and the second magnetic material layer 33 are etched together, and the second protective layer 34 and the second magnetic material layer 33 are surrounded by a third dielectric layer 43; the third dielectric layer 43 and the second protective layer 34 are subjected to a second chemical mechanical polishing until the second magnetic material layer 33 is exposed, and the polishing end point is when the reflected signal changes abruptly.

[0109] A second magnetic material layer 33 is disposed on the second dielectric layer 42. A second protective layer 34 covers the side of the second magnetic material layer 33 away from the magnetic tunnel junction 50. A third dielectric layer 43 is formed above the second protective layer 34 and covers the second protective layer 34, the second magnetic material layer 33, and the second dielectric layer 42. The second magnetic material layer 33 may include at least one of a cobalt layer, an iron layer, a nickel layer, a cobalt-iron layer, a cobalt-iron-boron layer, a nickel-iron layer (i.e., a permalloy layer), or a cobalt-platinum layer. The second protective layer 34 may be at least one of a silicon oxide layer, an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a silicon carbide nitride layer. The third dielectric layer 43 may be made of an insulating material, such as a low dielectric constant material or a high dielectric constant material. The third dielectric layer 43 and the second dielectric layer 42 may be made of the same or different materials, as may the third dielectric layer 43 and the second protective layer 34.

[0110] The second magnetic material layer 33 and the second protective layer 34 are etched together and have essentially the same shape and size. For example, the outer peripheral surfaces of the second magnetic material layer 33 and the second protective layer 34 are flush, forming a stacked pattern with aligned boundaries. The planar shape can be adapted to the shape of the magnetic tunnel junction 50. The outer peripheral surface of the second magnetic material layer 33 can protrude from the outer peripheral surface of the magnetic tunnel junction 50, that is, the orthogonal projection of the second magnetic material layer 33 on the substrate 10 covers the orthogonal projection of the magnetic tunnel junction 50 on the substrate 10.

[0111] The third dielectric layer 43 covers the top surface of the second protective layer 34 and also covers the top surface of the second dielectric layer 42, the sides of the second protective layer 34, and the second magnetic material layer 33. The third dielectric layer 43 and the second protective layer 34 are removed by a second chemical mechanical polishing process. When the polished surface approaches the second magnetic material layer 33, a significant difference in optical reflection characteristics between the second magnetic material layer 33 and the upper second protective layer 34 causes a sudden change in the online-monitored reflection signal, indicating that the second magnetic material layer 33 has been exposed. This is the endpoint of the polishing process. Chemical mechanical polishing can automatically detect the polishing endpoint using the magneto-optical Kerr effect, avoiding under-polishing and over-polishing. It eliminates the need for frequent preliminary batch experiments and fitting, enhancing process stability and reducing material costs.

[0112] As one possible implementation, after grinding the first protective layer 32 and the second dielectric layer 42 until the first magnetic material layer 31 is exposed, a fourth metal material 74a (such as tantalum), a second magnetic material 33a (such as soft magnetic materials like cobalt or nickel-iron), and a second protective material 34a are formed sequentially on the first magnetic material layer 31 and the second dielectric layer 42; the fourth metal material 74a, the second magnetic material 33a, and the second protective material 34a are etched to form a fourth metal layer 74, a second magnetic material layer 33, and a second protective layer 34; a third dielectric layer 43 is formed, which covers the fourth metal layer 74, the second magnetic material layer 33, the second protective layer 34, and the second dielectric layer 42; the third dielectric layer 43 and the second protective layer 34 are then subjected to a second chemical mechanical polishing. When polishing reaches the second magnetic material layer 33, the reflected signal will suddenly increase due to the magneto-optical Kerr effect, and this is taken as the end point of polishing.

[0113] In the first and second type embodiments described above, the structure under test is an out-of-plane magnetic tunnel junction 50 with vertical magnetization reversal without external field. A single magnetic material layer 20 or a magnetic material layer in a composite magnetic material layer assists the magnetic tunnel junction 50 in achieving field-free reversal. An out-of-plane magnetic tunnel junction 50 with vertical magnetization reversal without external field means that the magnetization direction of the free layer in the magnetic tunnel junction 50 is perpendicular to the thin film surface, and switching along the vertical direction can be completed solely by the torque generated by the write current itself. The magnetic material layer 20 or the magnetic material layer in the composite magnetic material layer is stacked perpendicularly to the magnetic tunnel junction 50. This magnetic material layer can adjust its magnetization direction without applying an external magnetic field, disrupting the symmetry of the spin Hall effect, thereby assisting the magnetic tunnel junction 50 in achieving reversal and increasing device density.

[0114] In the third possible embodiment, see Figures 18 to 22 The structure to be tested is a magnetic tunnel junction 50, with a fourth dielectric layer 44 covering the sides and top surface of the magnetic tunnel junction 50; a single magnetic material layer 20 covers the surface of the fourth dielectric layer 44, and a fifth dielectric layer 45 covers the single magnetic material layer 20; the grinding ends when the reflection signal disappears after the first chemical mechanical grinding of the fourth dielectric layer 44, the fifth dielectric layer 45 and the single magnetic material layer 20.

[0115] The magnetic tunnel junction 50 is a multilayer stacked structure with a free layer, a barrier layer, and a reference layer. The magnetic tunnel junction 50 is disposed on a substrate 10. A bottom electrode 60 may also be disposed between the magnetic tunnel junction 50 and the substrate 10. A fifth metal layer 75 is formed on the magnetic tunnel junction 50. A fourth dielectric layer 44 covers the sides and top surface of the magnetic tunnel junction 50. The fourth dielectric layer 44 can have good conformal properties, conformally covering the magnetic tunnel junction 50, the bottom electrode 60, and the substrate 10. A single magnetic material layer 20 covers the surface of the fourth dielectric layer 44, also having good conformal properties, conformally covering the fourth dielectric layer 44. A fifth dielectric layer 45 covers the surface of the single magnetic material layer 20 and fills the spaces between the magnetic tunnel junctions 50.

[0116] The single magnetic material layer 20 can be a cobalt layer, an iron layer, a nickel layer, a cobalt-iron layer, a cobalt-iron-boron layer, a nickel-iron layer (i.e., a permalloy layer), or a cobalt-platinum layer. The fourth dielectric layer 44 can be at least one of a silicon oxide layer, an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a silicon carbide nitride layer, to isolate the single magnetic material layer 20 from the magnetic tunnel junction 50. The fifth dielectric layer 45 can be at least one of a silicon oxide layer, an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a silicon carbide nitride layer, and the materials of the fifth dielectric layer 45 and the fourth dielectric layer 44 can be the same or different.

[0117] The fourth dielectric layer 44, the fifth dielectric layer 45, and the single magnetic material layer 20 are partially removed by the first chemical mechanical polishing. After the single magnetic material layer 20 is removed from the polished surface, the reflection signal monitored online gradually decreases and disappears due to the significant difference in optical reflection characteristics between the single magnetic material layer 20 and the underlying film. This point can be determined as the polishing endpoint. In this way, chemical mechanical polishing can automatically detect the polishing endpoint using the magneto-optical Kerr effect, avoiding under-polishing and over-polishing. It eliminates the need for frequent pre-batch processing, enhances process stability, and reduces material costs.

[0118] As one possible implementation, the structure under test is a magnetic tunnel junction 50, which is a multilayer stacked structure with a free layer, a barrier layer and a reference layer, etc., and the magnetic tunnel junction 50 is formed on the substrate 10. The grinding process for the grinding endpoint detection structure is as follows: A bottom electrode material 61 (such as tungsten, platinum, or other heavy metals), a magnetic tunnel junction film stack 51, and a fifth metal material 75a (such as tantalum) are sequentially stacked on a substrate 10. The bottom electrode material 61, the magnetic tunnel junction film stack 51, and the fifth metal material 75a are etched to form a bottom electrode 60, a magnetic tunnel junction 50, and a fifth metal layer 75. A fourth dielectric layer 44 is formed, covering the bottom electrode 60, the magnetic tunnel junction 50, and the fifth metal layer 75. A single magnetic material layer 20 is formed, covering the fourth dielectric layer 44 and surrounding the magnetic tunnel junction 50. A fifth dielectric layer 45 is formed, covering the single magnetic material layer 20. A first chemical mechanical grinding process is performed on the fourth dielectric layer 44, the fifth dielectric layer 45, and the single magnetic material layer 20. After grinding removes the single magnetic material layer 20 above the magnetic tunnel junction 50, the reflected signal gradually disappears due to the magneto-optical Kerr effect, marking this as the grinding endpoint.

[0119] See some possible examples. Figures 22 to 25 The grinding endpoint detection structure also includes: a sixth dielectric layer 46 and a first metal layer 71. The sixth dielectric layer 46 covers the fourth dielectric layer 44, the fifth dielectric layer 45 and the single magnetic material layer 20. A groove 46a is formed in the sixth dielectric layer 46. The first metal layer 71 fills the groove 46a and covers the top surface of the sixth dielectric layer 46. The first metal layer 71 is subjected to a second chemical mechanical grinding, and the grinding endpoint is determined by detecting the eddy current. The single magnetic material layer 20 shields the magnetic field generated by the eddy current detection to protect the magnetic tunnel junction 50.

[0120] The sixth dielectric layer 46 is a dielectric film layer disposed above the fourth dielectric layer 44, the fifth dielectric layer 45, and the single magnetic material layer 20. It serves as a carrier layer for the second chemical mechanical polishing (CMP) process and also covers the magnetic tunnel junction 50. The grooves 46a within the sixth dielectric layer 46 are partially open structures and can be etched. The planar shape of the grooves 46a can be circular, elliptical, rectangular, etc., and the depth of the grooves 46a can be greater than or equal to the thickness of the sixth dielectric layer 46 to achieve electrical connection with the magnetic tunnel junction 50. The material of the sixth dielectric layer 46 can be selected from silicon oxide, silicon oxynitride, silicon nitride, silicon carbide, other dielectric materials, or combinations thereof.

[0121] The first metal layer 71 fills the groove 46a and covers the sixth dielectric layer 46 outside the groove 46a. The material of the first metal layer 71 can be iron, cobalt, nickel, or their alloys. The first metal layer 71 undergoes a second chemical mechanical polishing process, and the pressure is automatically adjusted by eddy current, the polishing endpoint is detected, and the flatness is controlled. The polished first metal layer 71 can form a top electrode. By passing an alternating current through the coil, a magnetic field with a direction and magnitude that varies with time is generated around the coil. This magnetic field induces vortex-like currents (i.e., eddy currents) in the first metal layer 71. The single magnetic material layer 20 on the periphery of the magnetic tunnel junction 50 can shield this magnetic field, reducing its disturbance to the magnetization state and tunneling characteristics of the magnetic tunnel junction 50, so that the endpoint determination and the protection of the magnetic tunnel junction 50 are coordinated.

[0122] As one possible implementation, a sixth dielectric layer 46 is formed on the fourth dielectric layer 44, the fifth dielectric layer 45, and the single magnetic material layer 20 through a first chemical mechanical polishing process. The sixth dielectric layer 46 is then etched to form a groove 46a, which exposes the fifth metal layer 75. A first metal layer 71 is formed, which fills the groove 46a and extends onto the sixth dielectric layer 46. The first metal layer 71 is then chemically mechanically polished a second time, and the polishing endpoint is detected using eddy currents. As the first metal layer 71 thins, the eddy currents gradually weaken to determine whether the polishing endpoint has been reached.

[0123] In the above-described embodiments, the magnetic field generated by the magnetic material layer in the single magnetic material layer 20 or the composite magnetic material layer cancels out the stray magnetic field generated by the structure under test. The magnetic flux of the magnetic field generated by the magnetic material layer in the magnetic structure and the stray magnetic field generated by the structure under test is closed, forming a loop. The net magnetic flux is close to or equal to zero, avoiding magnetic leakage, thereby reducing magnetic crosstalk between adjacent structures under test, increasing integration density, and reducing write current, achieving low-power switching. For example, the structure under test is a magnetic tunnel junction 50. The magnetic field generated by the magnetic material layer in the single magnetic material layer 20 or the composite magnetic material layer cancels out the stray magnetic fields generated by the reference layer, fixing layer, antiferromagnetic structure (if any), and pinning layer (if any) in the magnetic tunnel junction 50.

[0124] In the above-described embodiments, the grinding endpoint detection structure further includes a monitoring structure 80. The monitoring structure 80 is disposed on the same layer as the structure under test and is correspondingly provided with a single magnetic material layer 20 or a composite magnetic material layer. The critical dimension of the monitoring structure 80 is larger than the critical dimension of the structure under test to ensure the strength of the reflected signal. The monitoring structure 80 is an enlarged pattern formed on the same layer as the structure under test, and a magnetic structure is formed synchronously thereon. The critical dimension (CD) refers to the smallest feature size, that is, the smallest pattern size in an integrated circuit that has the most critical impact on device performance. The monitoring structure 80 is positioned adjacent to or corresponding to the structure under test. The monitoring structure can use the same process material system as the structure under test and be formed simultaneously to ensure the consistency of the reflection characteristics. For example, the structure under test is a magnetic tunnel junction 50, and the monitoring structure is a dummy magnetic tunnel junction. With the help of a larger critical dimension, the monitoring structure 80 obtains stronger reflected light intensity and a higher signal-to-noise ratio under the same illumination conditions, and can output a more stable signal, making the grinding endpoint identification more stable.

[0125] It is understandable that, such as Figures 11 to 17 As shown, when the magnetic structure is a composite magnetic material layer, the composite magnetic material layer is simultaneously formed on the top surface of the magnetic tunnel junction 50 and the monitoring structure 80, and the composite magnetic material layer and the corresponding dielectric layer on the magnetic tunnel junction 50 and the monitoring structure 80 are processed simultaneously. When the magnetic structure is a single magnetic material layer 20, the single magnetic material layer 20 is simultaneously formed on the top and side surfaces of the magnetic tunnel junction 50, as well as the top and side surfaces of the monitoring structure 80. Figure 20As shown, before forming the single magnetic material layer 20, the fourth dielectric layer 44 on the monitoring structure 80 is removed. That is, there is no fourth dielectric layer 44 above the monitoring structure 80, but the fourth dielectric layer 44 exists above the magnetic tunnel junction 50, thereby reducing the top height of the single magnetic material layer 20 on the monitoring structure 80. Thus, during the first chemical mechanical polishing, when the reflection signal disappears, the fifth metal layer 75 on the monitoring structure 80 or on it is exposed, ensuring the exposure of the magnetic tunnel junction 50 or its fifth metal layer 75, thereby enabling subsequent electrical connections.

[0126] The grinding endpoint detection structure provided in this application provides a magnetic structure above the structure to be tested. By emitting linearly polarized light into the magnetic structure and determining the grinding endpoint based on the reflected signal formed after reflection by the magnetic structure, the modulation effect of the magnetic structure on the reflected signal can enhance the recognizability of the endpoint detection signal. This reduces the adverse effects of weak signal caused by relying solely on reflectivity differences and susceptibility to surface state disturbances, thereby improving the sensitivity and accuracy of grinding endpoint determination and enhancing the stability of the chemical mechanical grinding process.

[0127] See Figure 26 This application also provides a grinding endpoint detection device, including: a transmitter 91, a reflector 92, a polarizer polarizer 93, an analyzer polarizer 94, and a detector 95. The transmitter 91 emits a light beam; the reflector 92 is opposite to the transmitter 91 and is used to reflect the light beam onto the grinding endpoint detection structure; the polarizer polarizer 93 is disposed between the reflector 92 and the grinding endpoint detection structure and converts the light beam into linearly polarized light; the analyzer polarizer 94 is opposite to the grinding endpoint detection structure and allows the reflected signal formed after reflection by the grinding endpoint detection structure to pass through. The polarization directions of the analyzer polarizer 94 and the polarizer polarizer 93 are orthogonal and have a deflection angle; the detector 95 is opposite to the analyzer polarizer 94 and detects the reflected signal.

[0128] The polishing endpoint detection device can be disposed in the polishing pad 98 below the polishing pad 96. Both the polishing pad 96 and the polishing pad 98 have optical windows 99 to allow linearly polarized light and reflected signals to pass through. A polishing endpoint detection structure is disposed above the polishing pad 96, facing the polishing pad 96 and exposed within the optical window 99. The polishing endpoint detection structure is typically formed within the wafer 97, such as... Figure 26 As shown, wafer 97 is in contact with polishing pad 96 with its front side facing down, and relative motion occurs between the wafer and polishing pad 96. Combined with the chemical action of polishing slurry and mechanical friction, planarization is achieved by using the polishing endpoint detection structure.

[0129] Emitter 91 is a light source unit that outputs the initial beam, providing a stable incident light source and forming a recognizable optical signal link in conjunction with subsequent polarization and reflection. Emitter 91 emits light toward reflector 92, allowing the emitted beam to be deflected by reflector 92 and then illuminate the grinding endpoint detection structure. For example, emitter 91 can be an infrared laser emitter 91.

[0130] Reflector 92 is an optical path steering component positioned opposite to transmitter 91. It reflects the light beam output from transmitter 91 and guides it to the grinding endpoint detection structure, thereby changing the beam's propagation direction and allowing it to pass through the optical window 99 on the grinding pad 96. Reflector 92 is located between transmitter 91 and the grinding endpoint detection structure, with its reflective surface facing both transmitter 91 and the grinding endpoint detection structure, thus forming a folding detection optical path. For example, reflector 92 can be a distributed Bragg reflector (DBR), whose reflective surface can be set according to the incident angle of the light beam emitted by transmitter 91. The effective reflection area of ​​reflector 92 is slightly larger than the beam incident range to ensure that the beam edge is not truncated during reflection and to meet alignment requirements.

[0131] The polarizer polarizer 93 is a polarization modulation device disposed between the reflector 92 and the grinding endpoint detection structure. It converts the light beam, after being deflected by the reflector 92, into linearly polarized light, so that the reflected signal returned from the grinding endpoint detection structure can be identified using the polarization state change. The polarizer polarizer 93 is located between the reflector 92 and the grinding endpoint detection structure; the light beam passing through it forms a linearly polarized state with a defined polarization direction. The polarizer polarizer 93 can be a wire grid polarizer, a birefringent crystal polarizing prism, a polymer thin film polarizer, etc., and its polarization direction can be set according to requirements.

[0132] The analyzer polarizer 94 is an analytical polarization element positioned opposite the grinding endpoint detection structure. It selectively transmits the reflected signal generated after reflection from the grinding endpoint detection structure. The analyzer polarizer 94 is located between the grinding endpoint detection structure and the detector 95, and the reflected signal must pass through the analyzer polarizer 94 before entering the detector 95. The analyzer polarizer 94 can be a wire grid polarizer, a birefringent crystal polarizing prism, a polymer film polarizer, etc. The polarization direction of the analyzer polarizer 94 is orthogonal to the polarization direction of the polarizer polarizer 93 and has a deflection angle. This deflection angle is the deflection angle of the magneto-optical Kerr effect (i.e., the Kerr angle), which is affected by the magnetic field direction of the magnetic structure in the grinding endpoint detection structure.

[0133] Detector 95 is an optical signal receiving unit arranged opposite to the analyzer polarizer 94. It is used to detect the reflected signal after passing through the analyzer polarizer 94 and can further convert it into an electrical signal for subsequent use. Detector 95 can be a photodetector 95, a thermal detector 95, etc.

[0134] Emitter 91 emits a beam of light continuously or in a pulsed manner. After the beam's propagation direction is changed by reflector 92, it is guided to polarizer 93. Polarizer 93 selects the polarization of the incident light and forms linearly polarized light to match the longitudinal or polarimetric magneto-optical Kerr effect. This linearly polarized light then illuminates the surface of the grinding endpoint detection structure. When the grinding endpoint detection structure is in different removal states during the chemical mechanical polishing process, its magnetic structure causes changes in the polarization characteristics of the reflected light. The reflected signal passes through analyzer polarizer 94 and reaches detector 95. Detector 95 receives the intensity of the reflected signal and determines whether the grinding endpoint has been reached.

[0135] The grinding endpoint detection device provided in this application adopts an optical path relationship formed by a transmitter 91, a reflector 92, a polarizer 93, a grinding endpoint detection structure, an analyzer 94, and a detector 95. The determination of the grinding endpoint no longer relies solely on differences in ordinary reflection intensity, but instead utilizes the change in polarization response of the grinding endpoint detection structure as an indicator of the grinding endpoint. By keeping the analyzer polarizer 94 orthogonal to the polarizer polarizer 93 and setting a deflection angle, weak polarization changes can be selectively identified, making the reflected signal more suitable for real-time output during chemical mechanical polishing, thereby achieving stable determination of the grinding endpoint.

[0136] The embodiments or implementation methods described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between embodiments can be referred to accordingly. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this specification are only used to explain the relative positional relationships and motion relationships between components in a specific posture (as shown in the attached figure). If the specific posture changes, the directional indications will also change accordingly.

[0137] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0138] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection via an intermediate medium, or the internal connection or interaction between two components. Those skilled in the art can understand the specific meaning of these terms in the embodiments of this application based on the specific circumstances. The terms "first," "second," "third," etc. (if present) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0139] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A grinding endpoint detection structure, characterized in that, The grinding endpoint detection structure, applied to the structure under test, includes: A magnetic structure is disposed at least above the structure to be tested, wherein the magnetic structure is a single magnetic material layer or a composite magnetic material layer; The grinding endpoint is determined by the reflected signal formed after linearly polarized light is emitted onto the surface of the single magnetic material layer or the composite magnetic material layer and reflected by the magnetic structure. When the magnetic structure is a single magnetic material layer, the end of the grinding process is when the reflected signal disappears. When the magnetic structure is the composite magnetic material layer, the grinding endpoint occurs when the reflected signal undergoes a sudden change.

2. The grinding endpoint detection structure according to claim 1, characterized in that, The composite magnetic material layer includes a magnetic material layer and a protective layer located above the magnetic material layer.

3. The grinding endpoint detection structure according to claim 1, characterized in that, The single magnetic material layer fills the through-hole or trench and extends to the outside of the through-hole or trench, the through-hole or trench being formed in a first dielectric layer above the structure under test; The single magnetic material layer is subjected to chemical mechanical polishing, and the polishing ends when the reflected signal disappears. After polishing, the single magnetic material layer located in the through hole or trench is retained to form an interconnect structure.

4. The grinding endpoint detection structure according to claim 2, characterized in that, The structure under test is a magnetic tunnel junction; The composite magnetic material layer includes: A first magnetic material layer is disposed above the magnetic tunnel junction; A first protective layer is disposed above the first magnetic material layer, and a second dielectric layer is also formed above the first protective layer; The first magnetic material layer, the first protective layer, and the magnetic tunnel junction are jointly etched together to form the structure. The grinding process continues until the first magnetic material layer is exposed, and the grinding endpoint is reached when the reflected signal undergoes a sudden change. This process involves a first chemical mechanical grinding of the second dielectric layer and the first protective layer until the first magnetic material layer is exposed.

5. The grinding endpoint detection structure according to claim 4, characterized in that, The composite magnetic material layer further includes: A second magnetic material layer is disposed above the second dielectric layer; A second protective layer is disposed above the second magnetic material layer. The second protective layer and the second magnetic material layer are jointly etched together, and a third dielectric layer is filled around the second protective layer and the second magnetic material layer. The third dielectric layer and the second protective layer are subjected to a second chemical mechanical polishing until the second magnetic material layer is exposed. The polishing endpoint is reached when the reflected signal undergoes a sudden change.

6. The grinding endpoint detection structure according to any one of claims 3-5, characterized in that, The structure under test is a magnetic tunnel junction of the out-of-plane, field-free, vertical magnetization reversal type. The magnetic material layer in the single magnetic material layer or the magnetic material layer in the composite magnetic material layer assists the magnetic tunnel junction in achieving field-free reversal.

7. The grinding endpoint detection structure according to claim 1, characterized in that, The structure under test is a magnetic tunnel junction, and the sides and top of the magnetic tunnel junction are covered with a fourth dielectric layer. The single magnetic material layer covers the surface of the fourth dielectric layer, and the single magnetic material layer is covered with a fifth dielectric layer. The grinding process ends when the reflected signal disappears after the first chemical mechanical grinding of the fourth dielectric layer, the fifth dielectric layer, and the single magnetic material layer.

8. The grinding endpoint detection structure according to claim 7, characterized in that, Also includes: A sixth dielectric layer covers the fourth dielectric layer, the fifth dielectric layer, and the single magnetic material layer, and a groove is formed in the sixth dielectric layer; A first metal layer fills the groove and covers the top surface of the sixth dielectric layer; The first metal layer is subjected to a second chemical mechanical polishing, and the end point of the polishing is determined by detecting eddy currents. The single magnetic material layer shields the magnetic field generated by eddy current detection to protect the magnetic tunnel junction.

9. The grinding endpoint detection structure according to any one of claims 1-5 and 7-8, characterized in that, The magnetic field generated by the magnetic material layer in the single magnetic material layer or the composite magnetic material layer cancels out the stray magnetic field generated by the structure under test; And / or, The grinding endpoint detection structure further includes a monitoring structure, which is disposed on the same layer as the structure under test and is correspondingly provided with the single magnetic material layer or the composite magnetic material layer. The critical dimension of the monitoring structure is larger than the critical dimension of the structure under test to ensure the intensity of the reflected signal.

10. A grinding endpoint detection device, characterized in that, include: Transmitter, emits a beam of light; A reflector, opposite to the emitter, for reflecting the light beam onto the grinding endpoint detection structure as described in any one of claims 1-9; A polarizer polarizer is disposed between the reflector and the grinding endpoint detection structure to convert the light beam into linearly polarized light; The analyzer polarizer is opposite to the grinding end point detection structure, allowing the reflected signal formed after reflection by the grinding end point detection structure to pass through. The polarization direction of the analyzer polarizer is orthogonal to that of the polarizer polarizer and has a deflection angle. The detector, positioned opposite the polarizer of the analyzer, detects the reflected signal to determine the grinding endpoint.

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