Method for monitoring abnormity of deposition machine

Abstract

The invention discloses a method for monitoring abnormity of a deposition machine. The method comprises: providing a monitoring wafer comprising a partial hierarchical structure for forming a metal-insulator-metal structure, at least a portion of the underlying structure of the monitoring wafer being formed by a deposition machine to be monitored; performing upper electrode metal deposition treatment on the monitoring wafer; detecting whether an arc defect exists in the monitoring wafer after the upper electrode metal deposition treatment; and judging whether the deposition machine to be monitored is abnormal or not based on the detection result. The monitoring wafer preferably has a positive warpage value and a bottom low conductive layer (such as silicon nitride), and is more sensitive to abnormal discharge caused by deformation of a deposition machine process kit shield or grounding of a heater. Compared with the prior art, the method has the advantages that the monitoring sensitivity and accuracy are improved by utilizing a monitoring wafer structure sensitive to specific abnormity and characteristic arc defect detection, early warning and timely maintenance of machine abnormity can be realized, and the product yield is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for monitoring abnormalities of a deposition machine. Background Art

[0002] In semiconductor device manufacturing, physical vapor deposition (PVD) is a widely used technique for depositing metal thin films such as aluminum, titanium, and titanium nitride. Aluminum deposition (Al DEP) tools are key equipment for this process. Maintaining stable operation of these tools is crucial to ensuring product yield and device performance.

[0003] The aluminum deposition machine contains complex components such as process kits, which include shields, cover rings, and heaters. During long-term operation, these components may be worn or deformed. For example, the shield in the process kit may be deformed due to thermal stress and other reasons, causing the gap between it and the cover ring to become smaller. During the deposition process, the high voltage in the plasma environment may cause arcing at the narrow gap. This breakdown may further cause the heater to be grounded (normally, the heater is insulated from the ground by a ceramic ring), thereby generating an abnormal potential difference between the wafer and the grounded heater.

[0004] In addition, the chamber shadow effect in the PVD deposition process may cause more atoms or ions to be deposited in the center area of ​​the wafer than in the edge area. For certain specific wafer structures, such as wafers with positive warpage values ​​(i.e., the wafer is bowl-shaped with a central bulge close to the heater) and the bottom layer is a material with poor conductivity (such as silicon nitride, SiN), charges are more likely to accumulate in the center area of ​​the wafer. When there is a potential difference between the wafer and the heater caused by anomalies such as the deformation of the shield, this central charge accumulation will significantly increase the risk of arc defects in the center of the wafer. Specifically, this phenomenon is particularly prominent in the process of depositing titanium nitride (TiN) films (for example, as the upper electrode of a metal-insulator-metal (MIM) capacitor).

[0005] In the prior art, an offline method is usually used to monitor the status of the aluminum deposition machine. A common method is to use a bare wafer or a monitor wafer with a simple dielectric layer deposited (such as silicon dioxide deposited using tetraethoxysilane (TEOS)). However, this conventional monitor wafer has a simple structure, and its physical properties (such as warpage, surface conductivity, etc.) are quite different from those of the product wafers (product wafers) that carry complex device structures in actual production. Therefore, this type of monitor wafer is not sensitive to the above-mentioned central arc defects caused by the combined effects of shield deformation, heater grounding, and specific wafer structure. Even with the assistance of macroscopic detection methods such as infrared and visual inspection, it is difficult to effectively and timely detect potential abnormalities such as early deformation of internal components of the aluminum deposition machine (such as process kit shields).

[0006] When such anomalies in aluminum deposition tools go undetected, they continue to operate despite the problem, leading to arc defects in inline wafers, impacting product yield and reliability. For example, in MIM manufacturing at certain technology nodes (such as 90BCD), if an aluminum deposition tool exhibits an anomaly, subsequent TiN deposition will result in a noticeable central arc defect observed in the defect scan results of the product wafers.

[0007] Therefore, there is an urgent need to develop a new monitoring method that can more sensitively and effectively monitor (aluminum) deposition tools, especially abnormal conditions related to the deformation of process kit shielding parts, so as to carry out maintenance in a timely manner and ensure stable production. Summary of the Invention

[0008] The present application aims to solve the technical problems existing in the prior art. In the prior art, abnormal monitoring of deposition tools, especially physical vapor deposition (PVD) aluminum (Al) deposition tools, usually uses bare wafers or monitoring wafers deposited with a simple dielectric layer (such as TEOS). However, this method is not sensitive enough to detect specific abnormalities caused by deformation of internal components of the tool (such as the shield in the process kit) due to long-term use (for example, arc breakdown caused by a small gap between the shield and the cover ring, abnormal grounding of the heater, etc.). These abnormalities will change the electric field distribution within the tool and, under certain conditions (such as in the center of a wafer with positive warpage and poor bottom conductivity), induce arcing defects in the product wafer, especially during the subsequent deposition of top electrode materials such as titanium nitride (TiN). Due to the insufficient effectiveness of traditional monitoring methods, such tool abnormalities are often not discovered in a timely manner, resulting in the problem persisting, affecting the yield and reliability of inline products, and delaying necessary equipment maintenance.

[0009] Therefore, there is an urgent need in the art for a more effective and sensitive method for monitoring the above-mentioned types of anomalies in deposition tools (especially tools for depositing underlying structures such as aluminum layers) so that problems can be discovered in a timely manner and corrective measures can be taken.

[0010] To solve the above technical problems, the present invention provides a method for monitoring abnormalities in a deposition machine. The method includes the following steps:

[0011] Step 1: providing a monitoring wafer, wherein the monitoring wafer includes a partial hierarchical structure for forming a metal-insulator-metal (MIM) structure, wherein at least a portion of a lower structure of the partial hierarchical structure is formed using a deposition tool to be monitored;

[0012] Step 2: Performing upper electrode metal deposition processing on the monitoring wafer;

[0013] Step 3: Detecting whether arcing defects exist on the monitoring wafer after the top electrode metal deposition process; and

[0014] Step 4: Based on the detection results, determine whether the deposition machine to be monitored has any abnormality.

[0015] Preferably, in step 1, the deposition tool to be monitored is used to form a layer containing aluminum (Al) as a part of the underlying structure, and the deposition tool to be monitored may be an aluminum (Al) deposition tool.

[0016] Preferably, in step 1, the monitoring wafer has a positive bow value and is in a bowl-shaped shape before the upper electrode metal deposition process is performed.

[0017] Preferably, in step 1, part of the hierarchical structure includes an insulating material layer such as a silicon nitride (SiN) layer, and the silicon nitride layer is located below a bottom electrode metal to be formed subsequently.

[0018] Preferably, in step 2, the upper electrode metal may be titanium nitride (TiN).

[0019] Preferably, in step three, arc defects are detected by a defect scanning device, and the arc defects are specifically manifested as arc defects with a special distribution map (Special Map).

[0020] Preferably, in step four, the abnormality of the deposition tool to be monitored includes deformation of the shield of its process kit, which may cause the gap between the shield and the cover ring to decrease and break down during operation, or cause the heater of the deposition tool to be grounded.

[0021] Preferably, the method is an offline monitoring method.

[0022] Preferably, the method further comprises: when it is determined in step 4 that the deposition machine to be monitored has an abnormality, performing maintenance on the deposition machine or replacing components.

[0023] As described above, the method for monitoring abnormalities of a deposition machine of the present invention has the following beneficial effects:

[0024] The monitoring method provided in the present application, by using a monitoring wafer with a specific structure (such as a MIM structure precursor, positive warpage, and a low-conductivity material such as SiN between the plates), combined with subsequent upper electrode deposition and targeted arc defect (especially special spectrum arc defect) detection, can significantly improve the monitoring sensitivity and accuracy of abnormalities such as deformation of internal components (such as process kit shielding) of deposition machines (especially aluminum deposition machines), achieve early warning and effective monitoring of machine abnormalities, thereby facilitating timely maintenance and ensuring the stability of semiconductor production and product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the method for monitoring abnormalities of a deposition machine according to the present invention. DETAILED DESCRIPTION

[0026] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0027] See also Figure 1 , an embodiment of the present application provides a method for monitoring abnormalities of a deposition machine.

[0028] Step 1: Provide a monitoring wafer. The monitoring wafer includes a portion of a hierarchical structure used to form a metal-insulator-metal (MIM) structure, wherein at least a portion of the underlying structure within the portion of the hierarchical structure was formed using the deposition tool to be monitored. This step aims to prepare a specialized monitoring tool whose structural features can amplify or more easily reveal anomalies that may have been introduced by the deposition tool to be monitored during the formation of the underlying structure.

[0029] In some embodiments, in step 1, the deposition tool to be monitored is used to form a layer containing aluminum (Al) as part of an underlying structure. By using a monitoring wafer containing an aluminum underlying structure, specific product structures in actual production that are sensitive to the state of the aluminum deposition tool can be more accurately simulated. For example, the aluminum layer serves as the bottom electrode or a critical conductive layer in a MIM structure, and its deposition quality is directly related to the subsequent arc risk, thereby improving the targetedness and effectiveness of monitoring.

[0030] In some embodiments, the deposition tool to be monitored is an aluminum (Al) deposition tool. This method is particularly suitable for monitoring physical vapor deposition (PVD) aluminum deposition tools, which are widely used in semiconductor manufacturing. Components in these tools, such as shields, are susceptible to deformation due to prolonged use, leading to abnormal discharges that are difficult to detect using conventional methods. This method aims to address the difficulty of effectively detecting abnormalities in these internal components using existing technologies.

[0031] In some embodiments, in step 1, a portion of the hierarchical structure on the monitoring wafer is suitable for forming a metal-insulator-metal structure using a 90BCD process platform. The inherent physical properties of MIM structures formed using specific process platforms (such as the 90BCD platform) (such as warpage and underlying materials) make the monitoring wafer more sensitive to specific tool anomalies (such as arcing). Selecting a process platform that can achieve this specific structure helps produce a highly sensitive monitoring wafer.

[0032] In some embodiments, in step one, the monitoring wafer has a positive bow value before the upper electrode metal deposition process, and is bowl-shaped. This bowl-shaped warp (Wafer Bow is positive) makes the center area of ​​the wafer relatively closest to the heater (Heater) or other components in the deposition equipment in the subsequent process. In the event that there is an abnormality in the machine to be monitored (for example, causing the heater to be grounded or generating an abnormal electric field), the charge is more likely to gather at the nearest center point and form a sufficiently high potential difference between it and the heater or other components, thereby preferentially inducing an arc in the center area. This phenomenon amplifies the characteristic signal of the machine abnormality, facilitating subsequent detection.

[0033] In some embodiments, in step one, part of the hierarchical structure includes an insulating material layer such as a silicon nitride (SiN) layer, and the silicon nitride layer is located below the lower electrode metal to be formed subsequently. The silicon nitride layer here can be, for example, a layer below or below the insulating layer in the MIM structure. The silicon nitride layer generally has poor electrical conductivity, and its presence hinders the rapid lateral dissipation of the wafer surface (especially the charge accumulated during the subsequent deposition process). This causes the charge to accumulate more easily in specific areas (especially the central area closest to the anomaly source due to warping). This charge accumulation effect is superimposed on the positive warping effect, which significantly increases the probability and severity of arc defects in the subsequent upper electrode deposition step, thereby greatly improving the detection sensitivity of machine anomalies (especially those that cause abnormal electric fields or discharges).

[0034] In some embodiments, in step 1, the monitored wafer is a 12-inch wafer. Of course, this method is also applicable to wafers of other sizes, such as 8 inches. The specific size of wafer is selected mainly to match the current mainstream semiconductor production line equipment.

[0035] Step 2: Deposit the top electrode metal on the monitoring wafer. This step utilizes a previously prepared monitoring wafer that is sensitive to specific anomalies and performs subsequent deposition on it. This process itself may be affected by anomalies introduced in the previous step of the monitored tool, or under specific deposition conditions (which may be on the same tool or a different tool), it may expose or trigger potential problems (such as arcing) caused by previous steps or tool conditions.

[0036] In some embodiments, in step 2, the upper electrode metal is titanium nitride (TiN). Titanium nitride is a commonly used upper electrode material in MIM structures. The titanium nitride deposition step is selected as the link for triggering or showing arc defects because, during the deposition process, if the machine to be monitored has problems such as abnormal discharge caused by deformation of the shield, these problems will directly interfere with the normal formation of the titanium nitride film and leave characteristic arc defect traces on the wafer. Therefore, by checking the arc defects after TiN deposition, the status of the machine to be monitored (the machine that forms the lower structure) can be inferred.

[0037] In some embodiments, in step 2, the upper electrode metal deposition process is performed using other deposition machines. This approach allows the abnormal monitoring of the lower electrode deposition machine and the upper electrode deposition process to be performed on different physical equipment. Even if the upper electrode deposition is performed on a machine in good condition, if the lower electrode deposition machine to be monitored introduces some structural defects, stress or surface state changes in step 1, these changes make the monitoring wafer itself become abnormally sensitive to the electric field or plasma environment in any subsequent standard deposition process (for example, it is more prone to charge accumulation or breakdown), then when other machines perform upper electrode deposition later, problems from the lower electrode deposition machine to be monitored can still be exposed.

[0038] Step 3: Check the monitor wafer for arcing defects after the top electrode metal deposition process. By detecting specific defect types (arcing defects), it can be directly linked to abnormal discharge or electric field problems within the tool.

[0039] In some embodiments, in step three, the detection is performed by a defect scanning device, and the arc defect is specifically manifested as an arc defect with a special distribution map (Special Map). By using an automated defect scanning device (Defect Scantool), the entire wafer surface can be inspected quickly, objectively and comprehensively. Arc defects, especially arcs caused by the combined action of the above-mentioned machine hardware anomalies (such as shield deformation, heater grounding) and specific wafer structures (positive warping, poor bottom layer insulation), usually have unique morphology and characteristic spatial distribution patterns, such as being highly concentrated in the center area of ​​the wafer or presenting a specific radial, point or patchy map (ie, a "special distribution map"). Identifying arc defects with this special map can greatly improve the accuracy of judgment, distinguish it from other types of defects generated randomly, and thus more reliably point to specific machine abnormalities. Compared with traditional macroscopic inspections or conventional defect detection that only relies on bare chips or simple structure monitoring wafers, this can significantly improve the sensitivity and accuracy of detection, and can capture early abnormal signals such as deformation of internal machine components that traditional methods cannot effectively monitor.

[0040] In some embodiments, the defect scanning equipment is a Puma CYDFIK* machine. Using specialized, industry-standard, high-precision defect inspection equipment, such as KLA's Puma series inspection equipment, ensures the reliability, accuracy, and repeatability of inspection results. Of course, other equipment with similar or sufficient defect inspection capabilities may also be used.

[0041] Step 4. Based on the detection results, determine whether the deposition machine to be monitored has any abnormality. This step is to make a final judgment based on the detection results of step 3. For example, a judgment criterion for the number, density or special spectrum of arc defects can be preset. If the detected arc defects exceed the preset threshold, or a predefined special distribution spectrum is observed, it can be determined that the deposition machine to be monitored used to form the lower structure in step 1 has an abnormality. This judgment method based on specific defect characteristics has a higher confidence level than the traditional method that relies on process parameter (such as DC voltage) monitoring or general monitoring film, and can detect potential problems earlier and more accurately.

[0042] In some embodiments, in step 4, the abnormality of the deposition tool to be monitored includes deformation of the shield of its process kit. As described in the background, shield deformation is a common root cause of abnormal discharge and arcing within the equipment. By detecting arc defects caused by this deformation on specific monitoring wafers, this method can effectively indicate this type of hidden tool hardware problem that is usually difficult to directly observe.

[0043] In some embodiments, deformation of the shield reduces the gap between the shield and the cover ring, and arcing occurs at this gap during operation. This is the specific physical mechanism by which shield deformation causes problems. Deformation shortens the safe distance between the originally well-designed shield and the cover ring. Under the high voltage or strong plasma environment required by the PVD process, the electric field intensity at this narrow gap increases dramatically, exceeding the breakdown threshold, resulting in local discharge or arcing. This method can indirectly but effectively reflect this discharge problem caused by microstructural changes and its consequences (i.e., arc defects on the wafer).

[0044] In some embodiments, an abnormality in the deposition machine to be monitored causes the heater of the deposition machine to be grounded. Under normal circumstances, the heater and the equipment ground should be well insulated through components such as ceramic rings. If an abnormality occurs and causes the heater to be grounded, it will seriously change the electric field distribution inside the equipment, especially forming an unexpected and possibly high potential difference between the wafer and the heater. Combined with the charge accumulation phenomenon in the center of the wafer, this grounding abnormality can easily cause an arc. This method can also indirectly reflect the heater grounding abnormality that may be caused by shielding component breakdown or other reasons by detecting arc defects on the wafer.

[0045] In some embodiments, the present method is an offline monitoring method for assisting in determining the status of a deposition machine used in online production. By adopting an offline monitoring method, the target deposition machine can be regularly (for example, between each batch of production or at a predetermined cycle) or as needed (for example, when a suspected defect occurs in an online product) for health checks without interfering with or interrupting the normal online production process. Compared with the traditional offline monitoring using bare wafers or TEOS wafers, the use of the monitoring wafer and method proposed in this application, which are more sensitive to specific anomalies, can detect potential problems of the machine earlier and more accurately, such as early signs of deformation of the process kit shield. This provides a timely and effective basis for implementing preventive maintenance (PM), thereby avoiding or reducing the impact of abnormal conditions on online products and effectively ensuring the yield and stability of online products.

[0046] In some embodiments, the method further includes the following steps: Step 5: If the monitored deposition tool is determined to be abnormal in Step 4, maintenance or component replacement is performed on the deposition tool. This is the ultimate goal and practical application value of this monitoring method. Once a tool abnormality is confirmed through this method, appropriate corrective measures should be taken immediately. For example, production of the determined abnormal deposition tool can be promptly stopped (down tool), and engineers can be assigned to conduct a detailed inspection. Based on the inspection results, targeted maintenance can be performed, such as replacing deformed shields, cover rings, or other related process kit components, or repairing a fault point that causes the heater to ground. This timely maintenance action can effectively eliminate the source of the abnormality, restore the tool to normal operation, and prevent the related defect from continuing to affect online production. After detecting arc defects with special patterns using this method and promptly shutting down the tool to replace the kit, the subsequent test run (pi-run) results show normal results, indicating that the tool abnormality has been significantly improved, verifying the effectiveness of this monitoring method and subsequent maintenance measures. However, tools not monitored using this method may continue to be affected by the abnormality.

[0047] In summary, the monitoring method provided in the present application, by using a monitoring wafer with a specific structure (such as a MIM structure precursor, positive warping, and a bottom layer of a low-conductivity material such as SiN), combined with subsequent upper electrode deposition and targeted arc defect (especially special spectrum arc defect) detection, can significantly improve the monitoring sensitivity and accuracy of abnormalities such as deformation of internal components (such as process kit shielding) of deposition machines (especially aluminum deposition machines), achieve early warning and effective monitoring of machine abnormalities, thereby facilitating timely maintenance and ensuring the stability of semiconductor production and product yield.

[0048] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0049] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for monitoring abnormalities of a deposition machine, characterized in that: At least: Step 1: providing a monitoring wafer, wherein the monitoring wafer comprises a partial hierarchical structure for forming a metal-insulator-metal structure, wherein at least a portion of a lower structure in the partial hierarchical structure is formed using the deposition tool to be monitored; Step 2: performing an upper electrode metal deposition process on the monitoring wafer; Step 3: detecting whether the monitoring wafer after the upper electrode metal deposition process has arc defects; and Step 4: Based on the detection results, determine whether the deposition machine to be monitored has any abnormality.

2. The method for monitoring abnormalities of a deposition machine according to claim 1, characterized in that: In step 1, the deposition tool to be monitored is used to form a layer comprising aluminum as a part of the underlying structure.

3. The method for monitoring abnormalities of a deposition machine according to claim 1 or 2, characterized in that: The deposition machine to be monitored is an aluminum (Al) deposition machine.

4. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: In step 1, the partial hierarchical structure on the monitoring wafer is suitable for forming the metal-insulator-metal structure through a 90nm technology node BCD process platform.

5. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: In step 1, the monitoring wafer has a positive warpage value and is in a bowl-shaped shape before the upper electrode metal deposition process.

6. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: In step 1, the partial hierarchical structure includes an insulating dielectric layer, and the insulating dielectric layer is located below the upper electrode metal.

7. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: In step 1, the monitoring wafer is a 12-inch wafer.

8. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: In step 2, the upper electrode metal is titanium nitride.

9. The method for monitoring abnormalities of a deposition machine according to claim 1, characterized in that: In step 2, the upper electrode metal deposition process is performed using other deposition machines.

10. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: In step three, the detection is performed by a defect scanning device, and the arc defect is specifically manifested as an arc defect with a special distribution pattern.

11. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: In step 4, the abnormality of the deposition tool to be monitored includes deformation of a shielding component of its process kit.

12. The method for monitoring abnormalities of a deposition machine according to claim 11, characterized in that: The deformation of the shielding member causes the gap between the shielding member and the cover ring to decrease, and breakdown occurs at the position of the gap during operation.

13. The method for monitoring abnormalities of a deposition machine according to claim 11, wherein: The abnormality of the deposition tool to be monitored causes the heater of the deposition tool to be grounded.

14. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: The method is an off-line monitoring method used to assist in determining the status of a deposition machine used in online production.

15. The method for monitoring abnormalities of a deposition machine according to claim 1, wherein: The method further includes step five: when it is determined in step four that the deposition machine to be monitored has an abnormality, maintaining the deposition machine or replacing parts of the deposition machine.

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