Apparatus and method for monitoring chemical mechanical planarization polishing endpoint detection anomalies
By monitoring the wafer full-scan topography signal through the endpoint detection module, the problem of false detection caused by full-scan signal offset during chemical mechanical planarization grinding is solved, enabling real-time alarm and rework of abnormal wafers and preventing wafer scrap.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUA HONG SEMICON WUXI LTD
- Filing Date
- 2024-01-17
- Publication Date
- 2026-07-31
AI Technical Summary
In the existing chemical mechanical planarization (CMP) polishing process, the endpoint detection system may experience a full scan signal shift due to abnormal events, leading to false detections, insufficient wafer polishing, and no alarm from the machine. The defective wafers then flow out to subsequent sites for scrapping.
An endpoint detection module monitors the full-scan morphology signal of the wafer. A laser is emitted by a laser generation module and the signal is acquired by a light intensity detection module. Combined with the morphology signal of the polishing retaining ring, polishing abnormalities and offsets are judged, and alarms are triggered in real time and abnormal wafers are marked.
It enables real-time monitoring and alarm of full-scan anomalies, preventing abnormal wafers from leaving the wafer, avoiding wafer scrap, and ensuring the normal operation of subsequent process flows.
Smart Images
Figure CN117885031B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, and in particular to an apparatus and method for monitoring abnormalities at the endpoints of chemical mechanical planarization (CMP) polishing. Background Technology
[0002] For CMP (Chemical Mechanical Planarization) of metal layers such as W / CU, the main inline control method is to detect the grinding endpoint through an Endpoint Detection System (EPD). The EPD curve shape changes according to the different light intensities reflected from the film, thus stopping the process at the endpoint and achieving different grinding effects. During the process, the Endpoint Detection System collects signals of the wafer morphology in real time.
[0003] However, in actual production, some abnormal events may occur that cause the Full scan signal to deviate. The signal strength collected by the endpoint detection system software will change, and the curve will show abnormalities, triggering alarms or even false captures. False captures will cause insufficient wafer polishing (with gold residue) and no alarm on the machine. Problematic wafers will flow to subsequent stations and be scrapped.
[0004] For example, Figure 2 This illustrates the signal strength and full-scan topography signal collected by a point detection system software under normal conditions. Figure 3 The diagram illustrates the signal strength and full-scan topography signal collected by a point detection system software under full-scan signal offset conditions.
[0005] To address the aforementioned issues, a novel device and method for monitoring and detecting anomalies at the endpoints of chemimechanical planarization (CMP) grinding processes are required. Summary of the Invention
[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a device and method for monitoring abnormalities in the endpoint detection of chemical mechanical planarization (CMP) grinding. This is to solve the problem that in the prior art, some abnormal events may cause Fullscan signal deviation, changes in the signal strength collected by the endpoint detection system software, abnormal curves that trigger alarms or even false captures, and false captures may lead to insufficient wafer grinding (with gold residue) and no alarm from the machine, resulting in the defective wafers flowing to subsequent stations and being scrapped.
[0007] To achieve the above and other related objectives, the present invention provides an apparatus for monitoring abnormalities at the endpoints of chemical mechanical planarization (CMP) grinding processes, comprising:
[0008] Endpoint detection module, which is used to monitor the full-scan morphology signal of at least one film layer on a wafer during chemical mechanical planarization polishing;
[0009] The first detection module is used to determine whether the grinding process is abnormal based on the signal intensity of the full-scan morphology signal.
[0010] If yes, the wafer is marked as an abnormal wafer; otherwise, the wafer proceeds to the next process flow.
[0011] The second detection module is used to detect whether a shift has occurred during the full scan.
[0012] If yes, and the first detection module determines that no abnormality occurred during grinding, then the wafer is re-detected for defects; if not, the wafer proceeds to the next process flow.
[0013] Preferably, the wafer comprises a bulk semiconductor wafer or a silicon-on-insulator (SOI) wafer.
[0014] Preferably, the endpoint detection module uses the difference in the reflected light intensity of the film layer to obtain the full-scan morphology signal.
[0015] Preferably, the endpoint detection module includes: a laser generating module and a light intensity detection module disposed on a wafer grinding stage. A grinding pad is disposed on the wafer grinding stage, and the wafer is fixed by a grinding retaining ring on a wafer carrier head. The wafer rotates with the wafer carrier head and forms grinding contact with the grinding pad. The laser generating module is used to emit laser light to the film layer, and the light intensity detection module obtains the full-scan topography signal based on the laser light reflected by the film layer.
[0016] Preferably, the film layer is a metal layer.
[0017] Preferably, the metal layer is made of copper, titanium, tantalum, tungsten, or titanium nitride.
[0018] Preferably, the film layer is a non-metallic layer.
[0019] Preferably, the full-scan topography signal also includes the topography signal of the grinding retaining ring.
[0020] Preferably, the method for the second detection module to detect whether a full scan has shifted includes: acquiring the morphology signal of the polishing holding ring after the wafer has rotated at least one revolution; selecting regions that are symmetrical to each other at both ends of the wafer's central axis as the first and second regions; acquiring the first and second average thickness values at the first and second regions respectively based on the morphology signal of the polishing holding ring; determining whether the difference between the first and second average thickness values is within the control specification of the optical zero-point offset: if yes, then it is determined that no full scan has shifted; if no, then it is determined that a full scan has shifted.
[0021] The present invention also provides a method for monitoring anomalies at the endpoints of chemical mechanical planarization (CMP) grinding, comprising:
[0022] Continuously acquire full-scan morphology signals of at least one film layer on a wafer during chemical mechanical planarization (CMP) polishing;
[0023] The grinding process is determined based on the signal intensity of the full-scan morphology signal.
[0024] If yes, the wafer is marked as an abnormal wafer; otherwise, the wafer proceeds to the next process flow.
[0025] Determine whether any offset has occurred during the full scan.
[0026] If yes, and it is determined that no abnormality occurred during grinding, then the wafer is re-inspected for defects; if not, the wafer proceeds to the next process flow.
[0027] As described above, the apparatus and method for monitoring and detecting abnormalities at the endpoints of chemical mechanical planarization (CMP) grinding processes of the present invention have the following beneficial effects:
[0028] This invention can monitor full-scan anomalies. If an anomaly occurs during full-scan, it can issue an alarm in real time. The abnormal wafer will not be shipped out and can be reworked at the station, preventing the wafer from being scrapped. Attached Figure Description
[0029] Figure 1 The diagram shown is a schematic diagram of the endpoint detection structure of the present invention;
[0030] Figure 2 This diagram illustrates the signal strength and full-scan topography signal collected by a point detection system software under normal conditions in the prior art.
[0031] Figure 3 This diagram illustrates the signal strength and full-scan topography signal collected by a point detection system software under the condition of full-scan signal offset in the prior art.
[0032] Figure 4 The diagram shows a method for determining whether a full scan has shifted according to the present invention. Detailed Implementation
[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0034] This invention provides a device for monitoring abnormalities at the endpoints of chemical mechanical planarization (CMP) grinding processes, comprising:
[0035] Endpoint detection module 20 is used to monitor the full-scan morphology signal of at least one film layer on wafer 105 during chemical mechanical planarization polishing.
[0036] In one alternative embodiment, wafer 105 includes a bulk semiconductor substrate or a silicon-on-insulator (SOI) substrate. The SOI substrate includes an insulating layer beneath a thin semiconductor layer serving as the active layer. The semiconductor in the active layer and the bulk semiconductor typically include the crystalline semiconductor material silicon, but may also include one or more other semiconductor materials, such as germanium, silicon-germanium alloys, compound semiconductors (e.g., GaAs, AlAs, InAs, GaN, AlN, etc.) or alloys thereof (e.g., GaxAl1-xAs, GaxAl1-xN, InxGa1-xAs, etc.), oxide semiconductors (e.g., ZnO, SnO2, TiO2, Ga2O3, etc.), or combinations thereof. The semiconductor material may be doped or undoped. Other substrates that may be used include multilayer substrates, gradient substrates, or mixed-orientation substrates.
[0037] In one alternative embodiment, the film layer is a metal layer.
[0038] In one alternative embodiment, the material of the metal layer includes, but is not limited to, metallic materials such as copper, titanium, tantalum, tungsten, or titanium nitride.
[0039] In one alternative embodiment, the film layer is a non-metallic layer, such as a silicon layer, an oxide layer, or a nitride layer.
[0040] In one alternative implementation, the endpoint detection module 20 uses the difference in the intensity of light reflected from the film layer to obtain a full-scan topography signal.
[0041] In one alternative implementation, please refer to Figure 1 The endpoint detection module 20 includes a laser generating module 201 and a light intensity detection module 202 disposed on the wafer polishing stage 101. A polishing pad 102 is disposed on the wafer polishing stage 101. The wafer 105 is fixed by a polishing retaining ring 103 on the wafer carrier head 104. The polishing retaining ring 103 is usually made of wear-resistant materials such as ceramics, and its thickness hardly changes during the polishing process. The wafer 105 rotates with the wafer carrier head 104 and forms polishing contact with the polishing pad 102. The laser generating module 201 is used to emit laser light to the film layer, and the light intensity detection module 202 obtains the full-scan morphology signal based on the laser light reflected by the film layer.
[0042] In an alternative embodiment, the full scan topography signal also includes the topography signal of the polishing retaining ring 103.
[0043] The first detection module is used to determine whether the grinding process is abnormal based on the signal intensity of the full-scan morphology signal.
[0044] If yes, then mark wafer 105 as abnormal wafer 105; if no, then wafer 105 will proceed with the subsequent process flow.
[0045] The second detection module is used to detect whether a shift has occurred during the full scan.
[0046] If yes, and the first detection module determines that no abnormality occurred during grinding, then the wafer 105 is re-detected for defects; if not, the wafer 105 proceeds to the subsequent process flow.
[0047] In one alternative implementation, please refer to Figure 4 The method for the second detection module to detect whether a full scan has been offset includes: acquiring the morphology signal of the polishing holding ring 103 after the wafer 105 has rotated at least one revolution; selecting regions that are symmetrical to each other at both ends of the central axis of the wafer 105 as the first and second regions; acquiring the first and second average thickness values at the first and second regions respectively based on the morphology signal of the polishing holding ring 103; determining whether the difference between the first and second average thickness values is within the control specification of the optical zero-point offset: if yes, then it is determined that no full scan has been offset; if no, then it is determined that a full scan has been offset.
[0048] This invention can monitor full-scan anomalies. If an anomaly occurs during full-scan, it can trigger an alarm in real time. The abnormal wafer 105 will not be shipped out and can be reworked at the station, preventing the wafer 105 from being scrapped.
[0049] The present invention also provides a method for monitoring anomalies at the endpoints of chemical mechanical planarization (CMP) grinding, comprising:
[0050] Continuously acquire full-scan morphology signals of at least one film layer on wafer 105 during chemical mechanical planarization polishing;
[0051] Determine whether grinding abnormalities have occurred based on the signal intensity of the full-scan morphology signal;
[0052] If yes, then mark wafer 105 as abnormal wafer 105; if no, then wafer 105 will proceed with the subsequent process flow.
[0053] Determine whether any offset has occurred during the full scan.
[0054] If yes, and it is determined that no abnormality occurred during grinding, then wafer 105 is re-inspected for defects; if not, wafer 105 proceeds to the next process flow.
[0055] This invention can monitor full-scan anomalies. If an anomaly occurs during full-scan, it can trigger an alarm in real time. The abnormal wafer 105 will not be shipped out and can be reworked at the station, preventing the wafer 105 from being scrapped.
[0056] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0057] In summary, this invention can monitor full-scan anomalies. If an anomaly occurs during full-scan, it can issue a real-time alarm, preventing the defective wafer from leaving the site and allowing for rework at the same station, thus preventing wafer scrap. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.
[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A device for monitoring and detecting abnormalities at the endpoints of a chemical mechanical planarization (CMP) grinding process, characterized in that, At least including: An endpoint detection module is used to monitor the full-scan morphology signal of at least one film layer on a wafer during chemical mechanical planarization (CMP) polishing, wherein the full-scan morphology signal also includes the morphology signal of the polishing retaining ring. The first detection module is used to determine whether the grinding process is abnormal based on the signal intensity of the full-scan morphology signal. If yes, the wafer is marked as an abnormal wafer; otherwise, the wafer proceeds to the next process flow. The second detection module is used to detect whether a shift has occurred during the full scan. If so, and the first detection module determines that no abnormality has occurred during grinding, then the wafer is re-detected for defects. If not, the wafer will proceed with subsequent process flows; The method for the second detection module to detect whether a full scan has been offset includes: acquiring the morphology signal of the polishing holding ring after the wafer has rotated at least one revolution; selecting regions that are symmetrical to each other at both ends of the wafer's central axis as the first and second regions; acquiring the first and second average thickness values at the first and second regions respectively based on the morphology signal of the polishing holding ring; determining whether the difference between the first and second average thickness values is within the control specification of the optical zero-point offset: if yes, then it is determined that no full scan has been offset; if no, then it is determined that a full scan has been offset.
2. The device for monitoring and detecting abnormalities at the endpoints of chemical mechanical planarization grinding according to claim 1, characterized in that: The wafer comprises a bulk semiconductor substrate or a silicon-on-insulator (SOI) substrate.
3. The device for monitoring and detecting abnormalities at the endpoints of chemical mechanical planarization grinding according to claim 1, characterized in that: The endpoint detection module uses the difference in the reflected light intensity of the film layer to obtain the full-scan morphology signal.
4. The device for monitoring and detecting abnormalities at the endpoints of chemical mechanical planarization grinding according to claim 3, characterized in that: The endpoint detection module includes a laser generating module and a light intensity detection module disposed on a wafer polishing table. A polishing pad is disposed on the wafer polishing table, and the wafer is fixed by a polishing retaining ring on a wafer carrier head. The wafer rotates with the wafer carrier head and forms polishing contact with the polishing pad. The laser generating module is used to emit laser light to the film layer, and the light intensity detection module obtains the full-scan topography signal based on the laser light reflected by the film layer.
5. The device for monitoring and detecting abnormalities at the endpoints of chemical mechanical planarization grinding according to claim 1, characterized in that: The film layer is a metal layer.
6. The device for monitoring and detecting abnormalities at the endpoints of chemical mechanical planarization grinding according to claim 5, characterized in that: The metal layer is made of copper, titanium, tantalum, tungsten, or titanium nitride.
7. The device for monitoring and detecting abnormalities at the endpoints of chemical mechanical planarization grinding according to claim 1, characterized in that: The film layer is a non-metallic layer.
8. A method for monitoring and detecting anomalies at the endpoints of a chemical mechanical planarization (CMP) grinding process, characterized in that, At least including: Continuously acquire full-scan morphology signals of at least one film layer on a wafer during chemical mechanical planarization (CMP) polishing, wherein the full-scan morphology signals also include the morphology signal of the polishing retaining ring; The grinding process is determined based on the signal intensity of the full-scan morphology signal. If yes, the wafer is marked as an abnormal wafer; otherwise, the wafer proceeds to the next process flow. Determine whether any offset has occurred during the full scan. If yes, and it is determined that no abnormality occurred during grinding, then the wafer is re-inspected for defects; if no, the wafer proceeds to the next process flow. The method for determining whether a full scan has been offset includes: acquiring the morphology signal of the polishing holding ring after the wafer has rotated at least one revolution; selecting regions that are symmetrical to each other at both ends of the wafer's central axis as the first and second regions; acquiring the first and second average thickness values at the first and second regions respectively based on the morphology signal of the polishing holding ring; determining whether the difference between the first and second average thickness values is within the control specification of the optical zero-point offset: if yes, then it is determined that no full scan has been offset; if no, then it is determined that a full scan has been offset.