Grinding end point detection device and method and chemical mechanical grinding equipment

Abstract

The invention provides a grinding end point detection device and method and chemical mechanical grinding equipment, the grinding end point detection device is used for detecting a grinding end point of the chemical mechanical grinding equipment, the chemical mechanical grinding equipment comprises a grinding disc, a grinding pad is arranged on the front face of the grinding disc, and a first driving shaft is arranged on the back face of the grinding disc; the first driving shaft is used for driving the grinding disc to drive the grinding pad to rotate so as to grind a substrate, when the first driving shaft drives the grinding disc to rotate, the first driving shaft drives the closed coil to rotate synchronously, the closed coil cuts magnetic induction lines of a magnetic field of the magnet part when rotating, and current is generated on the closed coil; the grinding end point detection device can obtain the change condition of the rotating speed of the closed coil according to the change condition of the current so as to obtain the change condition of the rotating speed of the grinding disc, that is, the rotating speed abrupt change point of the grinding disc can be obtained by obtaining the current abrupt change point so as to determine the grinding end point.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and more specifically, relates to a grinding end point detection device, method and chemical mechanical grinding equipment. Background Art

[0002] With the improvement of integrated circuit integration, the device density and connection density in the circuit are increasing, the characteristic size of semiconductor devices is decreasing, and the requirements for wafer surface flatness are getting higher and higher. Chemical mechanical polishing (CMP) mainly flattens the wafer surface through chemical and physical effects, providing a good foundation for achieving smaller line widths. How to make chemical mechanical polishing more accurately polish to the stop layer (i.e. polishing endpoint detection) is the key to chemical mechanical polishing.

[0003] The existing chemical mechanical polishing endpoint detection methods mainly include light intensity endpoint detection method and eddy current endpoint detection method. The principle of light intensity endpoint detection is to determine the endpoint by detecting the change in the intensity of reflected light from different materials. When the material on the surface of the silicon wafer changes during the CMP process, the intensity of the reflected light will also change, thereby determining the endpoint of CMP; the working principle of the eddy current endpoint detection method is to detect the endpoint through the eddy current formed by the change in the cutting magnetic flux line range caused by the change in the polishing film thickness.

[0004] The above-mentioned light intensity endpoint detection method requires a large difference in reflectivity between thin film layers, and a window needs to be left on the polishing pad for collecting reflected light, which limits the wafer polishing area. The above-mentioned eddy current endpoint detection method is only applicable to metal film layers, which has great limitations. Summary of the invention

[0005] The purpose of the present invention is to provide a grinding endpoint detection device, method and chemical mechanical grinding equipment. The grinding endpoint detection method has no requirements on the reflectivity of the film layer, does not need to open a window on the grinding pad, can maximize the use area of ​​the grinding pad, and has no restrictions on the requirements for the grinding layer material.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a tube polishing endpoint detection device, which is used to detect the polishing endpoint of a chemical mechanical polishing device, wherein the chemical mechanical polishing device comprises a polishing disc, a polishing pad is arranged on the front side of the polishing disc, and a first driving shaft is arranged on the back side of the polishing disc, wherein the first driving shaft is used to drive the polishing disc to drive the polishing pad to rotate so as to polish the substrate; The grinding endpoint detection device includes an electromagnetic sensor and a detection unit. The electromagnetic sensor includes a magnet for generating a constant magnetic field and a closed circuit located in the magnetic field. The closed circuit includes a closed coil and an ammeter. The closed coil is connected to the first drive shaft in a transmission manner. The ammeter is used to measure the current on the closed coil. The detection unit is used to determine whether the grinding endpoint is reached based on the current.

[0007] In one embodiment, the grinding endpoint detection device further includes a second driving shaft, the closed coil is fixed on the second driving shaft, and the second driving shaft is drivingly connected to the first driving shaft.

[0008] In one embodiment, the grinding endpoint detection device also includes a first switching part, a transmission member is arranged between the second drive shaft and the first drive shaft, the first drive shaft is a stepped shaft, and the first switching part is used to switch the transmission member to a different position of the first drive shaft.

[0009] In one embodiment, the grinding endpoint detection device further includes a second switching portion, the second drive shaft is a stepped shaft, and the second switching portion is used to switch the transmission member to a different position of the second drive shaft.

[0010] In one embodiment, the transmission member is a conveyor belt or a chain. When the transmission member is a chain, the first drive shaft and the second drive shaft are both gear shafts.

[0011] In one embodiment, the detection unit is used to obtain the current and the current change rate or current change amount between adjacent first preset times, and determine whether the grinding end point is reached based on whether the current change rate or current change amount changes from greater than or equal to a first preset value to less than a second preset value, and the first preset value is greater than the second preset value.

[0012] A second aspect of the present invention provides a chemical mechanical polishing device, comprising a grinding disc and a grinding endpoint detection device as described above, wherein a grinding pad is arranged on the front side of the grinding disc, and a first driving shaft is arranged on the back side of the grinding disc, and the first driving shaft is used to drive the grinding disc to drive the grinding pad to rotate so as to grind the substrate.

[0013] In one embodiment, it further includes a driving motor and a controller, wherein the output end of the driving motor is fixedly connected to the first driving shaft, and the controller is used to control the driving motor to rotate at a fixed power.

[0014] A third aspect of the present invention provides a grinding endpoint detection method for detecting the grinding endpoint of a chemical mechanical grinding device. The detection method uses the grinding endpoint detection device as described above. The detection method comprises: The grinding disc is driven to grind the substrate at a preset fixed power; The current on the ammeter is obtained, and whether the grinding end point is reached is determined based on the current.

[0015] In one embodiment, determining whether the grinding endpoint is reached according to the current comprises: Obtaining a current change rate or a current change amount of the current within a first adjacent preset time; It is determined whether the current change rate or the current change amount changes from greater than or equal to a first preset value to less than a second preset value to determine whether the grinding end point is reached, and the first preset value is greater than the second preset value.

[0016] In one embodiment, in the obtaining of the current change rate or current change amount of the current within the adjacent first preset time, the current change rate is the absolute value of the current change within the first preset time divided by the current before the change and then divided by the first preset time.

[0017] In one embodiment, the grinding endpoint detection device further includes a second driving shaft, a first switching portion and a second switching portion, the closing coil is fixed on the second driving shaft, and the second driving shaft is drivingly connected to the first driving shaft; The first driving shaft is a stepped shaft, the first switching part is used to switch the transmission member to a different position of the first driving shaft, the second driving shaft is a stepped shaft, and the second switching part is used to switch the transmission member to a different position of the second driving shaft; characterized in that before the grinding disc is driven to grind the substrate with a preset fixed power, the method further includes: Obtaining the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer; When the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer is less than or equal to a third preset value, the first switching part and the second switching part move the transmission member to a first position, wherein the diameter of the first driving shaft corresponding to the first position is greater than the diameter of the second driving shaft corresponding to the first position; When the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer is greater than or equal to a fourth preset value, the first switching part and the second switching part move the transmission member to a second position, wherein the diameter of the first drive shaft corresponding to the second position is smaller than the diameter of the second drive shaft corresponding to the second position.

[0018] In one embodiment, when the difference between the friction coefficient of the layer to be ground and the friction coefficient of the stop layer is between the third preset value and the fourth preset value, the diameter of the first drive shaft corresponding to the transmission member is equivalent to the diameter of the second drive shaft corresponding to the transmission member.

[0019] In one embodiment, after the grinding time is greater than or equal to the second preset time, it is started to determine whether the grinding endpoint is reached.

[0020] The grinding endpoint detection device provided by the present invention is used to detect the grinding endpoint of a chemical mechanical grinding device. The chemical mechanical grinding device includes a grinding disc, a grinding pad is arranged on the front of the grinding disc, and a first driving shaft is arranged on the back of the grinding disc. The first driving shaft is used to drive the grinding disc to drive the grinding pad to rotate to grind the substrate. When the first driving shaft drives the grinding disc to rotate, the first driving shaft drives the closed coil to rotate synchronously. When the closed coil rotates, it cuts the magnetic flux lines of the constant magnetic field, and a current is generated on the closed coil. The change of the current can be used to obtain the change of the speed of the closed coil, thereby obtaining the change of the speed of the first driving shaft, that is, the change of the speed of the grinding disc. Due to the different friction coefficients of the grinding layer and the grinding stop layer, the grinding disc has different speeds when the grinding pad contacts different grinding layers under a fixed driving power. The speed of the grinding disc is different. The speed mutation point of the closed coil can be obtained through the current mutation point on the ammeter, thereby obtaining the speed mutation point of the grinding disc, thereby determining the grinding endpoint. The grinding endpoint detection device has no requirements on the reflectivity of the grinding film layer when in use, and there is no need to open a window on the grinding pad. The use area of ​​the grinding pad can be maximized, and there is no limitation on the requirements for the material of the grinding layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a grinding endpoint detection device provided in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a grinding endpoint detection device provided in an embodiment of the present invention; Figure 3 A schematic diagram of a grinding process provided by an embodiment of the present invention; Figure 4 A schematic diagram of a curve of current during a grinding process provided by an embodiment of the present invention; Figure 5 A schematic diagram of a curve showing the rate of change of current during the grinding process of an embodiment of the present invention; Figure 6 is a flow chart of a grinding endpoint detection method provided by an embodiment of the present invention; Figure 7It is a flow chart of the grinding endpoint detection method provided by an embodiment of the present invention.

[0023] Among them, the reference numerals in the figure are: 1-grinding end point detection device; 2-chemical mechanical polishing equipment; 3-substrate; 11-magnetic member; 12-closed coil; 13-galvanometer; 14-second drive shaft; 15-conductive slip ring; 16-first switching part; 17-transmission member; 18-second switching part; 21-grinding disc; 22-grinding pad; 23-first drive shaft; 24-motor; 111-first magnet; 112-second magnet. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be understood that the terms "including" and "having" and any variations thereof used herein are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0026] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. It should be understood that the term "and / or" used in this article is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0028] Existing chemical mechanical polishing endpoint detection methods mainly include light intensity endpoint detection method and eddy current endpoint detection method. The principle of light intensity endpoint detection is to determine the endpoint by detecting the change in the intensity of reflected light from different materials. When the material on the surface of the silicon wafer changes during the CMP process, the intensity of the reflected light will also change, thereby determining the endpoint of CMP; the working principle of the eddy current endpoint detection method is to detect the endpoint through the eddy current formed by the change in the range of the cutting magnetic lines of flux caused by the change in the grinding film thickness. The above-mentioned light intensity endpoint detection method requires a large difference in reflectivity between thin film layers, and a window needs to be left on the grinding pad for collecting reflected light, limiting the wafer grinding area. The above-mentioned eddy current endpoint detection method is only applicable to metal film layers, and has great limitations. Based on the above-mentioned problems, the present application provides a grinding endpoint detection device, method and chemical mechanical polishing equipment.

[0029] The polishing endpoint detection device, method and chemical mechanical polishing equipment provided by the present invention are described in detail below in conjunction with specific embodiments.

[0030] Figure 1 For a schematic diagram of the structure of the grinding endpoint detection device provided in an embodiment of the present invention, please refer to Figure 1 In a first aspect of the present embodiment, a polishing endpoint detection device 1 is provided for detecting a polishing endpoint of a chemical mechanical polishing device 2. The present embodiment is described in conjunction with the chemical mechanical polishing device 2. The chemical mechanical polishing device 2 of the present embodiment comprises a polishing disc 21, a polishing pad 22 is disposed on the front of the polishing disc 21, and a first driving shaft 23 is disposed on the back of the polishing disc 21. The first driving shaft 23 is used to drive the polishing disc 21 to drive the polishing pad 22 to rotate so as to polish the substrate 3.

[0031] The grinding endpoint detection device 1 of this embodiment includes an electromagnetic sensor and a detection unit. The electromagnetic sensor includes a magnet 11 for generating a constant magnetic field and a closed circuit located in the magnetic field. The closed circuit includes a closed coil 12 and an ammeter 13. The closed coil 12 is transmission-connected to the first drive shaft 23. The ammeter 13 is used to measure the current on the closed coil 12. The detection unit is used to determine whether the grinding endpoint is reached based on the current.

[0032] The grinding disc 21 of the chemical mechanical polishing device 2 of this embodiment faces the substrate 3 as the front side, a polishing pad 22 is fixed on the front side of the grinding disc 21, and the side of the grinding disc 21 away from the substrate 3 is the back side. The center of the back side of the grinding disc 21 is connected to a first drive shaft 23 for driving it to rotate. The first drive shaft 23 of this embodiment connects the drive motor 24 and the back side of the grinding disc 21. In this embodiment, the motor 24 is connected to a drive controller so that the motor 14 always drives the grinding disc 21 to rotate at a fixed power. Exemplarily, the substrate 3 of this embodiment is a wafer, and a layer to be polished is arranged on the wafer. The grinding endpoint detection device 1 of this embodiment is used to detect the grinding endpoint of the chemical mechanical polishing device 2. In the manufacturing process of integrated circuits, CMP technology plays a vital role. It is not only an efficient polishing technology, but also ensures the global flatness of the wafer surface. By combining chemical corrosion and mechanical grinding, CMP can accurately remove excess materials on the wafer, so that each layer of the integrated circuit reaches nanometer-level flatness, which provides an important foundation for subsequent processes such as lithography, etching, and thin film deposition. A grinding pad 22 is provided on the grinding disc 21 of the chemical mechanical grinding equipment 2 of this embodiment. The grinding disc 21 drives the grinding pad 22 to rotate. The grinding pad 22 grinds the substrate 3 during the grinding process. The grinding pad 22 can also store and transport polishing liquid, effectively discharge waste, transfer processing load, and ensure the stability of the polishing process.

[0033] The electromagnetic sensor of this embodiment includes a magnet 11, a closed coil 12 and an ammeter 13. The magnet 11 is used to generate a constant magnetic field. The closed coil 12 is located in the constant magnetic field and is used to cut the magnetic flux lines of the magnet 11. The ammeter 13 is used to measure the current on the closed coil 12. The magnet 11 of this embodiment can be two magnets arranged opposite to each other. Exemplarily, the magnet 11 of this embodiment includes two first magnets 111 and second magnets 112 arranged opposite to each other. A stable magnetic field is formed between the N pole of the first magnet 111 and the S pole of the second magnet 112. According to the principle of electromagnetic induction, the closed coil 12 of this embodiment forms a closed loop. In the process of the closed coil 12 cutting the magnetic flux lines of the magnet 11, an induced current is generated in the closed circuit. The magnitude of the induced current is proportional to the rate of change of the magnetic flux. It can be seen that the magnitude of the current in the closed circuit is proportional to the rotation speed of the closed coil 12. When the rotation speed of the closed coil 12 increases, the current in the closed circuit increases. When the rotation speed of the closed coil 12 decreases, the current in the closed circuit decreases. Since the closed coil 12 is transmission-connected to the first drive shaft 23, the present embodiment can obtain the change of the rotation speed of the first drive shaft 23, that is, the change of the rotation speed of the grinding disc 21, by obtaining the change of the current in the closed circuit. Exemplarily, the first drive shaft 23 and the closed coil 12 of the present embodiment are connected by a transmission member 17, wherein the transmission member 17 can be a transmission belt.

[0034] Since the friction coefficients of the layer to be ground and the grinding stop layer are different during the chemical mechanical grinding process, the driving motor 24 in this embodiment drives the grinding disc 21 to rotate at a fixed power. When the grinding disc 21 is grinding the layer to be ground and the grinding stop layer, the rotation speed of the grinding disc 21 is different. The grinding end point can be detected by grabbing the mutation point of the rotation speed of the grinding disc 21. Since the rotation speed change of the first driving shaft 23 is positively correlated with the rotation speed change of the closed coil 12, and the rotation speed change of the closed coil 12 is positively correlated with the current change on the ammeter 13, the mutation point of the rotation speed of the first driving shaft 23, that is, the mutation point of the rotation speed of the grinding disc 21, can be obtained by grabbing the mutation point of the current value on the closed coil 12 in this embodiment.

[0035] The grinding endpoint detection device 1 of the present embodiment can realize grinding endpoint detection by capturing the mutation point of the current on the ammeter 13 of the electromagnetic sensor 1. Compared with the existing optical endpoint detection method, the grinding endpoint detection device 1 of the present embodiment has no requirements on the reflectivity of the film layer to be ground and the grinding stop layer when performing endpoint detection. There is no need to set a detection window on the grinding pad 22, and the grinding pad 22 can maximize the use area. There is no need to wait for the rotation cycle during the detection process, which improves the accuracy of grinding endpoint detection. Moreover, the grinding endpoint detection device has no limitations on the requirements for the material of the grinding layer.

[0036] The grinding endpoint detection device provided in the present embodiment is used to detect the grinding endpoint of a chemical mechanical grinding device. The chemical mechanical grinding device includes a grinding disk, a grinding pad is arranged on the front side of the grinding disk, and a first driving shaft is arranged on the back side of the grinding disk. The first driving shaft is used to drive the grinding disk to drive the grinding pad to rotate so as to grind the substrate. The grinding endpoint detection device of the present embodiment drives the closed coil to rotate synchronously when the first driving shaft drives the grinding disk to rotate. When the closed coil rotates, it cuts the magnetic flux lines of the constant magnetic field, and generates current on the closed coil. The change in the rotation speed of the closed coil can be obtained through the change in the current, thereby obtaining the change in the rotation speed of the first driving shaft, that is, the change in the rotation speed of the grinding disk. Since the friction coefficients of the layer to be ground and the grinding stop layer are different, the rotation speed of the grinding disk is different when the grinding pad contacts different grinding layers under a fixed driving power. The rotation speed mutation point of the closed coil can be obtained through the current mutation point on the ammeter, thereby obtaining the rotation speed mutation point of the grinding disk, thereby determining the grinding endpoint.

[0037] Figure 2 For a schematic diagram of the structure of the grinding endpoint detection device provided in an embodiment of the present invention, please refer to Figure 2 In a specific embodiment, the grinding endpoint detection device 1 further includes a second drive shaft 14, the closed coil 12 is fixed on the second drive shaft 14, and the second drive shaft 14 is connected to the first drive shaft 23 in a transmission manner. The closed coil 12 of this embodiment is fixedly mounted on the second drive shaft 14, and a conductive slip ring 15 is provided on the second drive shaft 14. The output end and the input end of the ammeter 13 are connected to the closed coil 12 through the conductive slip ring 15. The manufacturing method of the detection device is simple. The second drive shaft 14 of the grinding endpoint detection device of this embodiment is connected to the first drive shaft 23 in a transmission manner, and the second drive shaft 14 rotates synchronously with the first drive shaft 23. For example, when the diameter of the first drive shaft 23 is the same as the diameter of the second drive shaft 14, the rotation speed of the first drive shaft 23 is the same as the rotation speed of the second drive shaft 14. This embodiment does not impose any special restrictions on the transmission connection method of the second drive shaft 14 and the first drive shaft 23. For example, the second drive shaft 14 is connected to the first drive shaft 23 in a transmission manner through a conveyor belt or a chain.

[0038] Exemplarily, the detection unit is used to obtain the current and the current change rate or current change amount between adjacent first preset times, and determine whether the grinding end point is reached based on whether the current change rate or current change amount changes from greater than or equal to a first preset value to less than a second preset value, and the first preset value is greater than the second preset value.

[0039] Specifically, Figure 3 A schematic diagram of a grinding process provided by an embodiment of the present invention, Figure 4 A schematic diagram of a curve of current during the grinding process provided by an embodiment of the present invention, Figure 5Schematic diagram of the curve of the current change rate during the grinding process of the embodiment of the present invention. Figure 3 The substrate 3 may include a substrate 3a and a layer 3b to be ground disposed on the substrate 3a. Preferably, a grinding stop layer 3c is also disposed on the substrate 3a and the layer 3b to be ground. The grinding stop layer 3c is mainly used to control the grinding depth in semiconductor manufacturing to ensure that the key structure is not over-ground, such as Figure 3 The process is shown in Step 1, and combined with Figure 4 and Figure 5 During the grinding process, the driving motor 24 driving the grinding disc 21 rotates at a fixed power, and the friction coefficient between the grinding pad 22 and the layer to be ground 3b directly affects the rotation speed of the grinding disc 21. When the contact surface of the grinding pad 22 and the substrate 3 (current grinding surface) is far away from the grinding stop layer 3c, the friction coefficient between the grinding pad 22 and the layer to be ground 3b is basically consistent, so that the rotation speed of the grinding disc 21 remains basically stable, that is, the current change rate is small, which can be less than or equal to the second preset value; Figure 3 The process is shown in Step 2, and combined with Figure 4 and Figure 5 As the layer to be ground 3b approaches the grinding stop layer 3c, the friction coefficient between the grinding pad 22 and the current grinding layer gradually transitions to the friction coefficient between the grinding pad 22 and the grinding stop layer 3c (the current grinding layer is flatter), that is, the rotation speed of the grinding disc 21 gradually decreases, and the current change rate (for example, about 20% / min) is always greater than the first preset value (for example, 15% / min); Figure 3 The process is shown in Step 3, and combined with Figure 4 and Figure 5 When grinding to the grinding stop layer 3c, the friction coefficient between the grinding pad 22 and the current grinding layer (i.e., the grinding stop layer 3c) is basically stable, and the rotation speed of the grinding disc 21 is basically stable (e.g., stable at 100r / min), that is, the current change rate can be less than or equal to the second preset value (e.g., 5% / min). Therefore, by monitoring the change rate of the current on the ammeter, the Figure 4 and Figure 5 The rotation speed mutation point shown in the dotted box is taken as the grinding end point.

[0040] In one specific embodiment, see Figure 1-Figure 3 The grinding endpoint detection device 1 also includes a first switching part 16, a transmission member 17 is arranged between the second drive shaft 14 and the first drive shaft 23, the first drive shaft 23 is a stepped shaft, and the first switching part 16 is used to switch the transmission member 17 to different positions of the first drive shaft 23. The first drive shaft 23 of the present embodiment is a stepped shaft. Exemplarily, the first drive shaft 23 is a stepped shaft whose diameter increases from top to bottom. The first switching part 16 is used to switch the transmission member 17 to different positions of the first drive shaft 23. Exemplarily, when the difference in friction coefficient between the grinding stop layer and the layer to be ground is small, the driving motor 24 drives the grinding disc 21 to rotate with a fixed power, and the rotation speed of the grinding disc 21 is not much different when the grinding pad 22 grinds the layer to be ground 3b and the grinding stop layer 3c, that is, the rotation speed change rate of the grinding disc 21 is small when the grinding pad 22 grinds the layer to be ground 3b and the grinding stop layer 3c. In the present embodiment, when the difference in friction coefficient between the grinding stop layer 3c and the layer to be ground 3b is small, the transmission member 17 is switched to the position of the largest diameter of the first drive shaft 23 by the first switching part 16, that is, when the grinding pad 22 grinds the layer to be ground 3b and the grinding stop layer 3c, a large change current can be generated, and the current change rate or current change amount can be improved, that is, the accuracy of the grinding end point capture can be improved. When the friction coefficient difference between the grinding stop layer 3c and the layer to be ground 3b is large, the first switching unit 16 switches the transmission member 17 to the position where the diameter of the first drive shaft 23 is the smallest, and the combination of the first drive shaft 23 with a small diameter and the second drive shaft 14 with a large diameter can generate a reasonable variable current in the grinding stop layer 3c to prevent excessive fluctuations in the rotation speed from damaging the stability of the machine. After the transmission member 17 of this embodiment is switched, the extension direction of the transmission member 17 is perpendicular to both the first drive shaft 23 and the second drive shaft 14.

[0041] For further information, see Figure 2 , Figure 3 The grinding endpoint detection device further includes a second switching portion 18 , the second drive shaft 14 is a stepped shaft, and the second switching portion 18 is used to switch the transmission member 17 to a different position of the second drive shaft 14 .

[0042] The second drive shaft 14 of this embodiment is a stepped shaft, and the second switching part 18 is used to switch the transmission member 17 to different positions of the second drive shaft 14. Exemplarily, when the difference in friction coefficient between the grinding stop layer 3c and the layer to be ground 3b is small, the rotation speed change rate of the grinding disc 21 is small when the grinding pad 22 grinds the layer to be ground 3b and the grinding stop layer 3c, the first switching part 16 switches the transmission member 17 to the position of the maximum diameter of the first drive shaft 23, and the second switching part 18 switches the transmission member 17 to the position of the minimum diameter of the second drive shaft 14, further enabling the grinding pad 22 to generate a larger variable current when grinding the layer to be ground 3b and the grinding stop layer 3c, further improving the sensitivity of the current change, and improving the accuracy of the grinding end point capture. When the difference in friction coefficient between the grinding stop layer 3c and the layer to be ground 3b is large, the rotation speed change rate of the grinding disc 21 is large when the grinding pad 22 grinds the layer to be ground 3b and the grinding stop layer 3c. The first switching part 16 switches the transmission member to the position of the smallest diameter of the first drive shaft 23, and the second switching part 18 switches the transmission member 17 to the position of the largest diameter of the second drive shaft 14. The combination of the first drive shaft 23 with the smallest diameter and the second drive shaft 14 with the largest diameter is adopted to further prevent the phenomenon that excessive fluctuation of the rotation speed causes damage to the stability of the machine. The first switching part 16 in the above embodiment is used to switch the position of the transmission member 17 on the first drive shaft 23, and the second switching part 18 is used to switch the position of the transmission member 17 on the second drive shaft 14. This embodiment does not impose any special restrictions on the specific structure of the first switching part 16 and the second switching part 18, as long as the switching of the position of the transmission member 17 can be realized, for example, the first switching part 16 and the second switching part 18 are both linear drive structures. When the position of the transmission member 17 needs to be switched, the linear drive structure moves the transmission member 17 to different positions. In order to ensure that the transmission member 17 is tensioned on the first drive shaft 23 and the second drive shaft 14 after the transmission member 17 is moved, the grinding endpoint detection device can be placed as a whole on a track that can be moved, and the transmission member 17 can be tensioned on the first drive shaft 23 and the second drive shaft 14 by moving the position of the grinding endpoint detection device.

[0043] Furthermore, the transmission member 17 is a conveyor belt or a chain. When the transmission member 17 is a chain, the first drive shaft 23 and the second drive shaft 14 are both gear shafts.

[0044] The grinding endpoint detection device provided by the embodiment of the present invention is used to detect the grinding endpoint of a chemical mechanical grinding device. The chemical mechanical grinding device includes a grinding disc, a grinding pad is arranged on the front of the grinding disc, and a first driving shaft is arranged on the back of the grinding disc. The first driving shaft is used to drive the grinding disc to drive the grinding pad to rotate to grind the substrate. When the first driving shaft drives the grinding disc to rotate, the first driving shaft drives the closed coil to rotate synchronously. When the closed coil rotates, it cuts the magnetic flux lines of the constant magnetic field, and a current is generated on the closed coil. The change of the current can be used to obtain the change of the speed of the closed coil, thereby obtaining the change of the speed of the first driving shaft, that is, the change of the speed of the grinding disc. Due to the different friction coefficients of the grinding layer and the grinding stop layer, the grinding disc has different speeds when the grinding pad contacts different grinding layers under a fixed driving power. The speed of the grinding disc is different. The speed mutation point of the closed coil can be obtained through the current mutation point on the ammeter, thereby obtaining the speed mutation point of the grinding disc, thereby determining the grinding endpoint. The grinding endpoint detection device has no requirements on the reflectivity of the grinding film layer when in use, and there is no need to open a window on the grinding pad. The use area of ​​the grinding pad can be maximized, and there is no limitation on the requirements for the material of the grinding layer.

[0045] The second aspect of this embodiment provides a chemical mechanical polishing equipment, including a grinding disk and a grinding endpoint detection device as described in the above embodiment, wherein a grinding pad is arranged on the front side of the grinding disk, and a first driving shaft is arranged on the back side of the grinding disk, and the first driving shaft is used to drive the grinding disk to drive the grinding pad to rotate so as to grind the substrate.

[0046] For example, the grinding endpoint detection device includes an electromagnetic sensor and a detection unit, the electromagnetic sensor includes a magnet for generating a constant magnetic field and a closed circuit located in the magnetic field, the closed circuit includes a closed coil and an ammeter, the closed coil is transmission-connected to the first drive shaft, the ammeter is used to measure the current on the closed coil, and the detection unit is used to determine whether the grinding endpoint is reached based on the current.

[0047] The chemical mechanical polishing equipment of this embodiment further includes a driving motor and a controller. The output end of the driving motor is fixedly connected to the first driving shaft, and the controller is used to control the driving motor to rotate at a fixed power.

[0048] The chemical mechanical polishing equipment provided in this embodiment includes a grinding disc and a grinding endpoint detection device. A grinding pad is provided on the front of the grinding disc, and a first driving shaft is provided on the back of the grinding disc. The first driving shaft is used to drive the grinding disc to drive the grinding pad to rotate so as to grind the substrate. The grinding endpoint detection device is used to detect the grinding endpoint of the chemical mechanical polishing equipment. The grinding endpoint detection device of this embodiment drives the grinding disc to rotate when the first driving shaft drives the grinding disc to rotate, and the first driving shaft drives the closed coil to rotate synchronously. When the closed coil rotates, it cuts the magnetic flux lines of the constant magnetic field, and a current is generated on the closed coil. The change in the current can be used to obtain the change in the rotation speed of the closed coil, thereby obtaining the change in the rotation speed of the first driving shaft, that is, the change in the rotation speed of the grinding disc. Since the friction coefficients of the layer to be polished and the grinding stop layer are different, the rotation speed of the grinding disc is different when the grinding pad contacts different polishing layers under a fixed driving power. The detection device can obtain the rotation speed mutation point of the closed coil through the current mutation point on the ammeter, thereby obtaining the rotation speed mutation point of the grinding disc, thereby determining the grinding endpoint.

[0049] Figure 6 is a flow chart of the grinding endpoint detection method provided by an embodiment of the present invention, please refer to Figure 6 The third aspect of this embodiment provides a grinding endpoint detection method for detecting the grinding endpoint of a chemical mechanical grinding device. The detection method uses the grinding endpoint detection device described in the above embodiment. The detection method includes: S101, driving the grinding disc to grind the substrate with a preset fixed power; Specifically, see Figure 1-Figure 3 The friction coefficient between the grinding pad 22 and the layer to be ground 3b will directly affect the rotational resistance of the grinding disc 21 (grinding pad). When the grinding disc 21 is driven to rotate with a preset fixed power, for example, the driving motor 24 is rotated with a constant input voltage, the friction coefficient (friction force) between the grinding pad 22 and the layer to be ground 3b of the substrate 3, that is, the material of the grinding surface of the substrate 3 will directly affect the rotational speed of the grinding disc 21. The closed coil 12 of the grinding end point detection device of this embodiment is connected to the first driving shaft 23 in a transmission manner. The closed coil 12 rotates synchronously with the first driving shaft 23. When the closed coil 12 rotates, it cuts the magnetic flux lines of the magnetic field, and an induced current is generated on the closed coil 12. The magnitude of the induced current is proportional to the rate of change of the magnetic flux. It can be seen that the magnitude of the current on the ammeter 13 of the closed circuit is proportional to the rotational speed of the closed coil 12, that is, the change in the rotational speed of the closed coil 12 can be obtained through the change in the current, thereby obtaining the change in the rotational speed of the first driving shaft 23, that is, the change in the rotational speed of the grinding disc 21. Since the friction coefficient between the grinding pad 22 and the layer to be ground 3b and the friction coefficient between the grinding pad 22 and the grinding stop layer 3c are different, when the grinding pad 22 contacts different grinding layers under a fixed driving power, the rotation speed of the grinding disk 21 is different.

[0050] S102, obtaining the current on the ammeter, and determining whether the grinding end point has been reached according to the current.

[0051] When the grinding wheel 21 rotates, even if the material of the current grinding surface remains unchanged (grinding the same film layer), the rotation speed of the grinding wheel 21 is not absolutely constant and will generally stabilize within a certain rotation speed range. When the current grinding surface gradually approaches the grinding stop layer 3c, due to the uneven surface morphology of the grinding stop layer 3c, the current grinding layer is composed of at least two materials and the material proportion of the grinding stop layer 3c gradually increases. During this process, the rotation speed of the first drive shaft 23 changes greatly. Since the closed coil 12 rotates synchronously with the first drive shaft 23, the rotation speed of the closed coil 12 also changes greatly, which makes the current on the ammeter 13 change greatly. When the stop layer 3c is completely ground, the rotation speed of the first drive shaft 23 changes relatively little, the rotation speed of the closed coil 12 changes relatively little, and the current on the ammeter 13 changes relatively little. Therefore, the material change of the current grinding surface can be judged by the change rate or change amount of the current between adjacent first pre-times, thereby determining the grinding end point. In this embodiment, the change in the rotation speed of the closed coil 12 can be obtained through the change in the current on the ammeter 13, thereby obtaining the change in the rotation speed of the first drive shaft 23, that is, the change in the rotation speed of the grinding disk 21. That is, by obtaining the mutation point of the current, the mutation point of the rotation speed of the grinding disk 21 can be obtained, thereby determining the grinding end point.

[0052] Figure 7 is a flow chart of the grinding endpoint detection method provided by an embodiment of the present invention, please refer to Figure 7 Exemplarily, determining whether the grinding endpoint is reached according to the current includes: S1021, obtaining a current change rate or a current change amount of the current within a first adjacent preset time period; Exemplarily, the step of obtaining the current change rate within the first preset time may include: obtaining a first current at the beginning of the first preset time (the current at the beginning) and a second current at the end of the first preset time (the current at the end), and the current change rate within the first preset time is the absolute value of the difference between the first current and the second current divided by the first current and then divided by the first preset time.

[0053] S1022. Determine whether the current change rate or current change amount changes from greater than or equal to a first preset value to less than a second preset value to determine whether the grinding end point is reached, and the first preset value is greater than the second preset value.

[0054] When the current change rate or the current change amount is less than the second preset value, it is determined that the current grinding surface is far away from the grinding stop layer 3c. When the current change rate or the current change amount is greater than or equal to the first preset value, it is determined that the current grinding surface is gradually approaching the grinding stop layer 3c. When the current change rate or the current change amount changes from greater than or equal to the first preset value to less than or equal to the second preset value, it is determined that the grinding reaches its end point. Among them, the first preset value is greater than the second preset value, and the first preset value and the second preset value can be determined according to the friction coefficient of the layer to be ground 3b and the grinding stop layer 3c (or substrate) (for example, the difference in friction coefficient). Among them, the first preset time can be determined by the monitoring frequency, and the current change rate and the current change amount in this embodiment are both absolute values. Exemplarily, the first preset value of the current change rate can be greater than or equal to 15% / min (for example, 15% / min~18% / min), and the second preset value can be less than or equal to 5% / min (for example, 2% / min~5% / min).

[0055] For further information, see Figure 2 and Figure 3 The grinding endpoint detection device of this embodiment further includes a second driving shaft 14, a first switching part 16 and a second switching part 18, the closed coil 12 is fixed on the second driving shaft 14, and a transmission member 17 is provided between the second driving shaft 14 and the first driving shaft 23; the first driving shaft 23 is a stepped shaft, the first switching part 16 is used to switch the transmission member 17 to different positions of the first driving shaft 23, the second driving shaft 14 is a stepped shaft, and the second switching part 18 is used to switch the transmission member 17 to different positions of the second driving shaft 14; before the grinding disc is driven to grind the substrate with a preset fixed power, it also includes: Obtaining the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer; When the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer is less than or equal to a third preset value, the first switching part and the second switching part move the transmission member to a first position, wherein the diameter of the first driving shaft corresponding to the first position is greater than the diameter of the second driving shaft corresponding to the first position; When the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer is greater than or equal to a fourth preset value, the first switching part and the second switching part move the transmission member to a second position, wherein the diameter of the first drive shaft corresponding to the second position is smaller than the diameter of the second drive shaft corresponding to the second position.

[0056] Specifically, the second drive shaft 14 of the detection device of this embodiment is connected with the first drive shaft 23 in transmission, and the second drive shaft 14 moves synchronously with the first drive shaft 23. When the diameter of the second drive shaft 23 remains unchanged, the larger the diameter of the first drive shaft 23, the more obvious the change in the rotation speed of the closed coil 12, the greater the change rate of the cutting magnetic flux lines, and the greater the change in the current on the ammeter 13. In this embodiment, the first drive shaft 23 and the second drive shaft 14 are both stepped shafts. When the difference in friction coefficient between the grinding stop layer 3c and the layer to be ground 3b is small, the combination of the first drive shaft 23 with a large diameter and the second drive shaft 14 with a small diameter can generate a larger change current in the grinding stop layer, thereby improving the sensitivity of the grinding end point detection; when the difference in friction coefficient between the grinding stop layer 3c and the layer to be ground 3b is large, the combination of the first drive shaft 23 with a small diameter and the second drive shaft 14 with a large diameter can generate a reasonable change current in the grinding stop layer 3c, thereby preventing the grinding disc 21 from fluctuating too much in rotation speed and causing permanent damage to the stability of the machine.

[0057] Optionally, in a specific embodiment, when the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer is between the third preset value and the fourth preset value, the first switching part and the second switching part are controlled to move the transmission member to a third position, wherein the diameter of the first drive shaft corresponding to the third position is equivalent to the diameter of the second drive shaft. In this embodiment, when the difference between the friction coefficient of the layer to be ground 3b and the friction coefficient of the grinding stop layer 3c is between the third preset value and the fourth preset value, when the diameter of the first drive shaft 23 is equivalent to the diameter of the second drive shaft 14, during the grinding process, when approaching the grinding stop layer 3c, that is, approaching the grinding end point, the current generated on the ammeter 13 changes significantly, and the sensitivity of the grinding end point detection can be ensured without adjusting the position of the transmission member 17.

[0058] In the above embodiment, the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer refers to the absolute value of the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer. The third preset value and the fourth preset value in the above embodiment can be obtained by performing multiple tests to obtain the change of the current on the ammeter 13 when the friction coefficient of the layer to be ground 3b and the friction coefficient of the grinding stop layer 3c are known and the diameter of the first drive shaft 23 is the same as the diameter of the second drive shaft 14.

[0059] In the above embodiment, after the grinding time is greater than or equal to the second preset time, it starts to determine whether the grinding endpoint is reached.

[0060] Please combine Figure 2 and Figure 3, when the current grinding surface is far from the grinding stop layer 3c, the current on the ammeter 13 is large and the current change rate is less than or equal to the second preset value; as the current grinding layer approaches the grinding stop layer 3c, the current on the ammeter 13 gradually decreases and the current change rate is always greater than the first preset value; when grinding to the grinding stop layer 3c, the current on the ammeter 13 no longer decreases and the current change rate may be less than or equal to the second preset value, wherein, Figure 4 and Figure 5 The current mutation point shown in the dotted box is the grinding end point. Of course, in the actual grinding process, after the current drops to a stable state, it can be properly over-grinded for a few seconds, that is, the actual grinding end point can be slightly delayed from the above-mentioned current mutation point.

[0061] The grinding endpoint detection method of this embodiment is used to detect the grinding endpoint of a chemical mechanical grinding device. The detection method includes driving the grinding disc to grind the substrate with a preset fixed power, obtaining the current on the ammeter, and determining whether the grinding endpoint is reached according to the current. When the first drive shaft drives the grinding disc to rotate, the first drive shaft drives the closed coil to rotate synchronously. When the closed coil rotates, it cuts the magnetic flux lines of the constant magnetic field, and generates current on the closed coil. The change in the current can be used to obtain the change in the speed of the closed coil, thereby obtaining the change in the speed of the first drive shaft, that is, the change in the speed of the grinding disc. Due to the different friction coefficients of the grinding layer and the grinding stop layer, the grinding disc has different speeds when the grinding pad contacts different grinding layers under a fixed driving power. The speed mutation point of the closed coil can be obtained through the current mutation point on the ammeter, thereby obtaining the speed mutation point of the grinding disc, thereby determining the grinding endpoint. When using this grinding endpoint detection method, there is no requirement for the reflectivity of the grinding film layer, and there is no need to open a window on the grinding pad. The use area of ​​the grinding pad can be maximized, and there is no limitation on the requirements for the material of the grinding layer.

[0062] In the above description, the description with reference to the terms "an embodiment", "some embodiments", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0063] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A grinding endpoint detection device, used for detecting the grinding endpoint of a chemical mechanical grinding device, wherein the chemical mechanical grinding device comprises a grinding disc, a grinding pad is arranged on the front of the grinding disc, and a first driving shaft is arranged on the back of the grinding disc, wherein the first driving shaft is used for driving the grinding disc to drive the grinding pad to rotate so as to grind a substrate; characterized in that: The grinding endpoint detection device includes an electromagnetic sensor and a detection unit. The electromagnetic sensor includes a magnet for generating a constant magnetic field and a closed circuit located in the magnetic field. The closed circuit includes a closed coil and an ammeter. The closed coil is connected to the first drive shaft in a transmission manner. The ammeter is used to measure the current on the closed coil. The detection unit is used to determine whether the grinding endpoint is reached based on the current.

2. The grinding endpoint detection device according to claim 1, characterized in that: The grinding endpoint detection device also includes a second driving shaft, the closed coil is fixed on the second driving shaft, and the second driving shaft is drivingly connected to the first driving shaft.

3. The grinding endpoint detection device according to claim 2, characterized in that: The grinding endpoint detection device also includes a first switching part, a transmission member is provided between the second drive shaft and the first drive shaft, the first drive shaft is a stepped shaft, and the first switching part is used to switch the transmission member to a different position of the first drive shaft.

4. The grinding endpoint detection device according to claim 3, characterized in that: The grinding endpoint detection device further includes a second switching portion, the second drive shaft is a stepped shaft, and the second switching portion is used to switch the transmission member to a different position of the second drive shaft.

5. The grinding endpoint detection device according to claim 3, characterized in that: The transmission member is a conveyor belt or a chain. When the transmission member is a chain, both the first drive shaft and the second drive shaft are gear shafts.

6. The grinding endpoint detection device according to any one of claims 1 to 5, characterized in that: The detection unit is used to obtain the current and the current change rate or current change amount between adjacent first preset times, and determine whether the grinding end point is reached based on whether the current change rate or current change amount changes from greater than or equal to a first preset value to less than a second preset value, and the first preset value is greater than the second preset value.

7. A chemical mechanical polishing device, characterized in that: It comprises a grinding disc and the grinding endpoint detection device according to any one of claims 1 to 6, wherein a grinding pad is arranged on the front side of the grinding disc, and a first driving shaft is arranged on the back side of the grinding disc, and the first driving shaft is used to drive the grinding disc to drive the grinding pad to rotate so as to grind the substrate.

8. The chemical mechanical polishing equipment according to claim 7, characterized in that: It also includes a driving motor and a controller. The output end of the driving motor is fixedly connected to the first driving shaft, and the controller is used to control the driving motor to rotate at a fixed power.

9. A grinding endpoint detection method for detecting the grinding endpoint of a chemical mechanical grinding device, the detection method using the grinding endpoint detection device of claim 1, characterized in that: The detection method comprises: The grinding disc is driven to grind the substrate at a preset fixed power; The current on the ammeter is obtained, and whether the grinding end point is reached is determined based on the current.

10. The grinding endpoint detection method according to claim 9, characterized in that: Determining whether the grinding end point is reached according to the current comprises: Obtaining a current change rate or a current change amount of the current within a first adjacent preset time; It is determined whether the current change rate or the current change amount changes from greater than or equal to a first preset value to less than a second preset value to determine whether the grinding end point is reached, and the first preset value is greater than the second preset value.

11. The grinding endpoint detection method according to claim 10, characterized in that: In the obtaining of the current change rate of the current within the adjacent first preset time, the current change rate is the absolute value of the current change within the first preset time divided by the current before the change and then divided by the first preset time.

12. The grinding endpoint detection method according to claim 10, wherein the grinding endpoint detection device further comprises a second drive shaft, a first switching portion and a second switching portion, the closing coil is fixed on the second drive shaft, and the second drive shaft is drivingly connected to the first drive shaft; The first drive shaft is a stepped shaft, the first switching portion is used to switch the transmission member to a different position of the first drive shaft, the second drive shaft is a stepped shaft, and the second switching portion is used to switch the transmission member to a different position of the second drive shaft; characterized in that Before the grinding disc is driven to grind the substrate with a preset fixed power, the method further comprises: Obtaining the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer; When the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer is less than or equal to a third preset value, the first switching part and the second switching part move the transmission member to a first position, wherein the diameter of the first driving shaft corresponding to the first position is greater than the diameter of the second driving shaft corresponding to the first position; When the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer is greater than or equal to a fourth preset value, the first switching part and the second switching part move the transmission member to a second position, wherein the diameter of the first drive shaft corresponding to the second position is smaller than the diameter of the second drive shaft corresponding to the second position.

13. The grinding endpoint detection method according to claim 12, characterized in that: When the difference between the friction coefficient of the layer to be ground and the friction coefficient of the grinding stop layer is between the third preset value and the fourth preset value, the first switching part and the second switching part move the transmission member to a third position, wherein the diameter of the first drive shaft corresponding to the third position is equivalent to the diameter of the second drive shaft corresponding to the third position.

14. The grinding endpoint detection method according to any one of claims 10 to 13, characterized in that: After the grinding time is greater than or equal to the second preset time, it is started to determine whether the grinding end point is reached.

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