SYSTEM AND METHOD FOR CONTROLLING CHEMICAL MECHANICAL PLANARIZATION

A chemical mechanical planarization system includes a chemical mechanical planarization head configured to hold a semiconductor wafer during a chemical mechanical planarization process. The system includes a camera positioned to capture an image of the chemical mechanical planarization after chemical mechanical planarization has unloaded the semiconductor wafer. A control system analyzes the image to determine if the chemical mechanical planarization head is damaged. If the chemical mechanical planarization head is damaged, the control system prevents further chemical mechanical planarization operations until the chemical mechanical planarization head is repaired. If the control system does not detect any damage, then the control system permits the chemical mechanical planarization head to receive a next semiconductor wafer for chemical mechanical planarization.

BACKGROUND

Technical Field

The present disclosure relates to the field of chemical mechanical planarization.

Description of the Related Art

There has been a continuous demand for increasing computing power in electronic devices including smart phones, tablets, desktop computers, laptop computers and many other kinds of electronic devices. Integrated circuits provide the computing power for these electronic devices. One way to increase computing power in integrated circuits is to increase the number of transistors and other integrated circuit features that can be included for a given area of semiconductor substrate. Accordingly, many semiconductor processes and techniques have been developed to decrease the size of features in integrated circuits.

Chemical mechanical planarization is a process that has enabled the use of thin film materials that enable features of relatively small size. Chemical mechanical planarization can planarize the surface of a semiconductor wafer after thin film deposition and patterning processes. Chemical mechanical planarization utilizes chemical and mechanical processes to planarize the semiconductor wafer. While highly beneficial, chemical mechanical planarization can also be susceptible to equipment failure resulting in damaged semiconductor wafers.

DETAILED DESCRIPTION

In the following description, many thicknesses and materials are described for various layers and structures within an integrated circuit die. Specific dimensions and materials are given by way of example for various embodiments. Those of skill in the art will recognize, in light of the present disclosure, that other dimensions and materials can be used in many cases without departing from the scope of the present disclosure.

Embodiments of the present disclosure provide many benefits over traditional chemical mechanical planarization systems. Embodiments of the present disclosure utilize an image capturing system and machine learning techniques to detect damage or other flaws in chemical mechanical planarization equipment before the equipment can damage a semiconductor wafer. Embodiments of the present disclosure reduce the need for technicians or experts to stop operation of the chemical mechanical planarization equipment in order to manually inspect chemical mechanical planarization equipment. Instead, the image capture system and machine learning modules can detect damaged equipment during operation and can automatically stop operation if damage is detected. The result is that fewer resources are utilized in inspecting and operating chemical mechanical planarization equipment. Furthermore, fewer expensive semiconductor wafers will need to be scrapped due to damaged chemical mechanical planarization equipment.

FIG. 1is an illustration of a chemical mechanical planarization (CMP) system100, according to one embodiment. The CMP system100includes one or more planarization stations, one or more CMP heads, a wafer load and unload unit106, a control system108, and a camera110. The components of the CMP system100cooperate to provide an efficient CMP process that detects equipment damage before a semiconductor wafer can be damaged by the equipment.

In one embodiment, during a CMP process, a semiconductor wafer (not shown inFIG. 1) is transferred to the wafer load and unload unit106by a transfer system. The wafer load and unload unit106receives the semiconductor wafer and ensures that the semiconductor wafer is positioned for pickup. Typically, the wafer load and unload unit106receives the semiconductor wafer face down such that a surface to be planarized is facing downward.

In one embodiment, after the wafer load and unload unit106has received and positioned the semiconductor wafer for pickup, a CMP head104picks up the wafer from the wafer load and unload unit106. The CMP head104typically holds the semiconductor wafer face down such that the surface to be planarized is facing downward and is exposed. The CMP head104may hold the semiconductor wafer by a pressure differential that prevents the semiconductor wafer from falling downward.

In one embodiment, the CMP head104includes a retaining ring, not shown inFIG. 1. The retaining ring laterally surrounds the circumference of the semiconductor wafer when the semiconductor wafer is held by the CMP head104. The retaining ring prevents the semiconductor wafer from moving laterally during planarization.

After the semiconductor wafer has been loaded into the CMP head104, the CMP head104moves to a planarization station102. The planarization station102performs a planarization processes on the semiconductor wafer in conjunction with the CMP head104. The planarization station102includes a circular horizontal surface covered by a CMP pad. The planarization station102also includes a slurry delivery system and a pad conditioning system. During the planarization process, the horizontal surface and the CMP pad are rotated. The CMP head104also rotates. The slurry delivery system delivers a liquid slurry material onto the rotating pad. The rotating CMP head104presses the downward facing surface of the semiconductor wafer onto the rotating pad. The rotating pad and the slurry material planarized the surface of the semiconductor wafer by mechanically and chemically removing protruding features from the surface of the semiconductor wafer. In this way, the CMP system100planarized is a surface of a semiconductor wafer.

In practice, the CMP head104may travel between multiple planarization stations102. A planarization processes performed on the semiconductor wafer at each planarization station102. After the CMP head104has carried the semiconductor wafer to each planarization station102, the CMP process is complete for that semiconductor wafer.

In one embodiment, after the CMP process is complete, the CMP head104carries the semiconductor wafer to the wafer load and unload unit106. The CMP head104positions the semiconductor wafer directly over the wafer load and unload unit106and lowers the semiconductor wafer onto the wafer load and unload unit106. The CMP head104then releases the semiconductor wafer into the wafer load and unload unit106. The transfer system then retrieves the semiconductor wafer from the wafer load and unload unit106. The transfer system then transfers a new semiconductor wafer to the wafer load and unload unit106, the CMP head104retrieves the semiconductor wafer, and the CMP process is performed again.

It is possible that during the previous CMP process, the CMP head104has become damaged. The damage can include cracks, scratches, or even more substantial breakage in the CMP head104. If the CMP head104takes part in another CMP process, then it is possible that the semiconductor wafer can become damaged. If the semiconductor wafer is damaged, is possible that the semiconductor wafer will have to be scrapped. In some cases, individual integrated circuit die diced from the semiconductor wafer will be nonfunctional, resulting in problems for users of the integrated circuit. In any of these cases, scrapping, fixing, or replacing damaged wafers or integrated circuits can be extremely costly in terms of human, computing, and monetary resources.

In some cases, the restraining ring of the CMP head104becomes damaged. The damage to the restraining ring can result from debris from a CMP pad during the CMP process, from crystallization of slurry materials on the restraining ring, or from scratches from diamond components of the CMP pad.

One approach to addressing the damage is to manually stop the CMP system100so that a human technician, expert, or engineer can visually examine the restraining ring or other parts of the CMP head104. Typically the individual enters the CMP load and unload area and examines the CMP head104with a flashlight in order to detect any damage. If a human checks the CMP head104after each CMP process, then this results in a large delay in the CMP processes. If a human checks the CMP head104only periodically after a selected number of CMP processes, then it is possible that a damaged CMP head104will go undetected for a large number of CMP processes. In this case, a large number of semiconductor wafers may be damaged in between checks. One additional problem is that even very minor damage to the CMP head104can result in damage to semiconductor wafers. Such minor damage is often difficult or impossible to detect by mere observation by a human. Accordingly, even very frequent inspection of the CMP head104may not be able to prevent damage to semiconductor wafers during CMP processes.

The CMP system100overcomes these problems by utilizing the camera110and the control system108. The camera110is positioned to capture images of the CMP head104after the CMP head104has deposited the semiconductor wafer on the wafer load and unload unit106and before the CMP head104has received a new semiconductor wafer from the wafer load and unload unit106. The camera110captures pictures of the CMP head104from a position below the CMP head104. Accordingly, the camera110captures images of the bottom of the CMP head104.

In one embodiment, the CMP system100utilizes multiple cameras110. Each of the cameras110can capture images of the CMP head104from various angles. There can be one or more cameras110positioned to capture images of the CMP head104from various angles below the CMP head104. There can be one or more cameras positioned to capture images of the CMP head104from positions substantially lateral to the CMP head104. There can be one or more cameras110positioned to capture images of the CMP head104from various angles above the CMP head104.

In one embodiment, one or more of the cameras110are positioned to capture images of the restraining ring of the CMP head104. One or more cameras110can capture images of a bottom surface of the restraining ring. One or more cameras110can capture images of an interior restraining surface of the restraining ring. The interior restraining surface can be the surface that laterally surrounds the lateral edges of the semiconductor wafer during the CMP process.

The camera110passes the images to the control system108. The control system108analyzes the images in order to detect damage to the CMP head104. The control system108can utilize image processing techniques to compare the CMP head104, or components of the CMP head104, to reference images of an undamaged CMP head, or components of an undamaged CMP head. If there are differences between images of the CMP head104and the reference images, then the control system108can determine that the CMP head104is damaged.

In one embodiment, the CMP head104includes an analysis model that has been trained with one or more machine learning processes to detect damage to the CMP head104. The machine learning process can train the analysis model to accurately identify when the CMP head104, or particular components of the CMP head104, are damaged. Further details regarding the machine learning process are provided in relation toFIG. 4.

In one embodiment, the control system108controls the function of the CMP system100. The control system108can be communicatively coupled to the CMP head104, the wafer load and unload unit106, and to the planarization stations102. The control system108can control the function of these components. The control system108can activate or deactivate the components of the CMP system100.

In one embodiment, if the control system108detects damage to the CMP head104, then the control system108can stop the CMP processes before another semiconductor wafer is loaded into the wafer load and unload unit106. Accordingly, upon detecting damage to the CMP head104based on images captured by the camera110, the control system108can prevent a next CMP process from happening. Thus, the damaged CMP head104will not be used in another CMP process until the damage component has been replaced or repaired. In this way, no semiconductor wafers will be damaged in CMP processes outside of the CMP process that initially damage the CMP head104.

It is possible that a semiconductor wafer that was loaded in the CMP head104during the process that damaged the CMP head104will have sustained damage during the CMP process. However, no further semiconductor wafers will be damaged by the CMP head104because the camera110and the control system108cooperate to detect damage to the CMP104the real time before another CMP process can be performed. Accordingly, the CMP system100, in accordance with principles of the present disclosure, greatly reduces the number of semiconductor wafers that may be damaged.

FIG. 2is a top view of a CMP system200, according to one embodiment. The CMP system200includes a frame114, a wafer load and unload unit106, and three planarization stations102. The CMP system200also includes a camera110and a control system108.

In the example ofFIG. 2, the frame114is coupled to four CMP heads104. The CMP heads104are each connected to the frame114by a respective shaft (not visible in the top view ofFIG. 2). The shaft can enable and drive rotation of the CMP head104. The shaft can also raise and lower the CMP head104relative to the frame of114. Alternatively, the frame114itself can be raised and lowered. The frame114can rotate in order to move the CMP heads104between the wafer load and unload unit106and the various planarization stations102.

In one embodiment, each planarization station102includes a CMP pad116positioned on a circular platen (not visible in the top view ofFIG. 2). Each planarization station102includes a respective slurry supply arm118and a respective pad conditioner120.

The three planarization stations102facilitate simultaneous processing of multiple wafers in a short time. During operation of the CMP system200, the platens rotate, thereby rotating the CMP pads116. During operation, the slurry supply arms118are positioned over the CMP pads116. The slurry supply arms118supply a slurry onto the CMP pads116. During operation, the pad conditioners120are swept over the respective CMP pads116for conditioning of the CMP pads116. In particular, the pad conditioners120includes a rotating head that rotates while in contact with the rotating CMP pad116. The head conditions the rotating CMP pad116.

In one embodiment, a robot arm122delivers a wafer124to the wafer load and unload unit106. A CMP head104is lowered onto the wafer load and unload unit106in order to retrieve the wafer from the wafer load and unload unit106. As described previously in relation toFIG. 1, the CMP head104can hold the semiconductor wafer124via a combination of pressure and a lateral retaining ring. Further details of the lateral retaining ring will be shown in relation toFIGS. 3A and 3B.

After the CMP head104retrieves a semiconductor wafer from the wafer load and unload unit106, the frame114rotates clockwise to position the CMP head104over a first planarization station102. The CMP head104presses the exposed surface of the semiconductor wafer124downward onto the rotating pad116. The CMP head104may itself rotate the semiconductor wafer124. The pad conditioner120conditions the CMP pad116. The slurry supply arm118supply slurry onto the rotating pad116. After this process is complete, the frame114again rotates counterclockwise to position the CMP head104over the next planarization station102and the planarization process is repeated. The frame114again rotates clockwise to position the CMP head104over the next planarization station102and the planarization process is repeated.

After the CMP head104has carried the semiconductor wafer124to each planarization station102, the frame114is rotated clockwise again to position the CMP head104over the wafer load and unload unit106. The CMP head104delivers the planarized semiconductor wafer124to the wafer load and unload unit106. The robot arm122retrieves the planarized semiconductor wafer124from the wafer load and unload unit106.

The CMP system200includes a camera110. The camera110is positioned adjacent to the wafer load and unload station106. After the CMP head104has delivered the planarized semiconductor wafer124to the wafer load and unload station106, the camera110captures one or more images of the CMP head104. As described in relation toFIG. 1, the camera110may be positioned to capture an image from below the CMP head104. There may be multiple cameras110positioned in various locations to capture images of various aspects of the CMP head104.

The control system108analyzes the images of the CMP head104in order to determine if the CMP head104has been damaged. The control system108can include image processing nodules or systems configured to analyze the images of the CMP head104. If the control system108detects damaged to a component of the CMP head104, then the control system108stops operation of the CMP system200until the CMP head104can be replaced or repaired. Further details regarding the control system108are provided in relation toFIG. 4.

FIG. 2illustrates one example of a CMP system200. A CMP system200can include different components, different arrangements of components, and different functions without departing from the scope of the present disclosure.

FIG. 3Ais a simplified side sectional view of a CMP head104positioned above a wafer load and unload unit106. A semiconductor wafer124is not shown inFIG. 3A. The CMP head104includes a retainer ring132coupled to a bottom portion of the CMP head104. The CMP head104is coupled to the frame114(seeFIG. 2) by a shaft130.

The CMP head104includes air passages140and the flexible membrane142. An air passage140extensor the shaft130and branches into a plurality of air passages140that extends to the flexible membrane142. Though not shown inFIG. 3A, the flexible membrane142includes a plurality of smaller air passages or pores. A vacuum system in the frame114or elsewhere can pump they are through the air passages140after the shaft130in order to generate a vacuum in the air passages140and in the course of the flexible membrane142.

When the CMP head104is ready to receive a waiver from the wafer load and unload unit106, the CMP head104is lowered to the wafer bad and unload unit106which holds a wafer (not shown inFIG. 3A). When the flexible membrane142is positioned near and directly above the wafer, the vacuum system activates a generative vacuum in the air passages140and in the pores of the flexible membrane142. The result is that the wafer is held by the flexible membrane142by vacuum suction. Likewise, when the CMP head104is ready to deliver a wafer to the wafer bad and unload unit106after a CMP process, the vacuum system removes a vacuum condition in the wafer is no longer held against the flexible membrane142. The wafer is released onto the wafer load and unload unit106.

In one embodiment, the retainer ring132includes an interior surface133and a bottom surface135. The interior surface133defines a gap134. When the CMP head104retrieves a semiconductor wafer from the wafer load and unload unit106, the semiconductor wafer124is held in the gap134defined by the interior surface133of the retaining ring132. The CMP head104holds the semiconductor wafer124and the vertical direction via an air pressure differential, as described above. The CMP head104holds the semiconductor wafer124in the lateral direction via the retainer ring132. In particular, the interior surface133of the retainer ring132laterally surrounds and restrains the semiconductor wafer124when the semiconductor wafer124is positioned in the gap134.

In one embodiment, the wafer load and unload unit includes a shelf136. When a semiconductor wafer124is loaded into the wafer load and unload unit106, the semiconductor wafer124rests on the shelf136. The CMP head104can be lowered to retrieve a semiconductor wafer124from the wafer load and unload unit106.

In one embodiment, the wafer load and unload unit106includes gaps or channels138. Cleaning fluids can be output from the gaps138to dean the CMP head104. Accordingly, the wafer load and unload unit106can include fluid nozzles positioned in the gaps138. The fluid nozzles can output a cleaning fluid to dean the CMP head104before the robot arm122(seeFIG. 2) delivers the next semiconductor wafer124to the wafer load and unload unit106. Accordingly, in one embodiment, the wafer load and unload unit106is a Head Clean Load/Unload (HCLU) unit.

The retainer ring132defines an inner diameter D1. The inner diameter D1corresponds to the diameter of the interior surface133of the retainer ring132. In one embodiment, the inner diameter is between 302 mm and 305 mm. In this case, the CMP head104may be configured to hold a 300 mm wafer. The inner diameter D1of the retainer ring132can be based on the size of wafer that the CMP head104is designed to hold. Furthermore, the inner diameter D1can have values other than that described above without departing from the scope of the present disclosure.

The retainer ring132defines an outer diameter D2. The outer diameter D2corresponds to the diameter of the outer surface139. In one embodiment, the outer diameter D2is between 329 mm and 335 mm, in the case of a CMP head104designed to hold 300 mm wafers. The outer diameter D2can have different values without departing from the scope of the present disclosure. Furthermore, the outer diameter D2may vary based on the size of wafer that the CMP head104is designed to hold.

The retainer ring132has a thickness T. The thickness T corresponds to the distance between the bottom surface135and the surface of the CMP head104to which the retainer ring132is attached. In one example, the retainer ring132has a thickness T between 31 mm and 35 mm. The retainer ring132can have other thicknesses without departing from the scope of the present disclosure

During CMP operations, the bottom surface135of the retainer ring132contacts the CMP pad116at a planarization station102(seeFIG. 2). If either the bottom surface135or the interior surface133is damaged during operation, then the semiconductor wafer124may be damaged in subsequent CMP operations. In order to detect damage to the bottom surface135or the interior surface133of the retainer ring132, a camera110is positioned adjacent to the wafer load and unload unit106below the CMP head104. The camera110is configured to capture images of the CMP head104from an angle below the CMP head104. The camera110is configured to pass the images to the control unit110(seeFIG. 2).

Typically, an area of the retainer ring132that is susceptible to damage is near a corner where the interior surface133meets the bottom surface135. If this area of the retainer ring132is damaged, it is likely that a semiconductor wafer held by the retainer ring132will be damaged during a CMP process. Damage to the retainer ring132may be difficult to detect with the human eye.

FIG. 3Aillustrates a damaged area137of the retainer ring132. The damaged area137is at a location where the interior surface133meets the bottom surface135. In practice, the damaged area137may occur at the junction of the interior surface133and the bottom surface135, on the interior surface133, on the bottom surface135, or on both the interior surface133and the bottom surface135depending on the extent of the damage.

In one embodiment, the camera110is configured to capture images of the area of the retainer ring132at which the interior surface133meets the bottom surface135. Because the retainer ring132is circular, the camera110can capture images along the inner circumference of the retainer ring132to detect if any portion of the retainer ring132has sustained damage.

In one embodiment, the camera110is positioned with an angle Θ relative to vertical. The angle Θ can be selected so that the camera110can capture images of a selected portion of the retainer ring132. Because, in one example, it is desirable to obtain images of both the interior surface133and the bottom surface135, the camera110can be positioned to capture images of the interior surface133a bottom surface135and a portion of the interior surface133and bottom surface135opposite to the lateral position of the camera110. In one example, the angle Θ is selected to be between 45° and 70° relative to vertical, though other angles can be selected based on the position of the camera110and the portion of the retainer ring132to be photographed. When there are multiple cameras110, the cameras can out the same angle Θ or different angles Θ in accordance with their position and the desired portions of the retainer ring132can be captured.

In one embodiment, the control system108can cause the CMP head104to rotate so that the camera110can capture images along the entire inner circumference of the retainer ring132. The control system108can cause the CMP head104to rotate in a stepwise manner such that the CMP head104periodically stops so that the camera110can capture an image. The CMP head104can make a full rotation in this manner until the camera110is captured images along the entire inner circumference of the retainer ring132. Capturing images of the entire inner circumference of the retainer ring132can include capturing images of the interior surface133, the bottom surface135, the area where the interior surface133meets the bottom surface135, or both the interior surface133and the bottom surface135. In one embodiment, the CMP head104can rotate in a continuous manner while the camera110captures images until the CMP head104has made a full rotation and the camera110is captured images along the entire interior surface133and bottom surface135of the retainer ring132.

In one embodiment, the camera110can pivot or otherwise move to capture images all along the desired surface or surfaces of the retainer ring132. For example, the camera110can capture an image of the retainer ring at one location, then rotate or move to capture images of another location of the retainer ring132. The camera110can move until images have been captured of all desired locations. In this case, the camera110may be positioned at a location directly below the CMP head104so that the camera110can capture images of the entire inner surface133, bottom surface135, or the area where the inner surface133meets the bottom surface135.

In one embodiment, there may be multiple cameras110positioned below the CMP head. The cameras110can be configured to capture images of the CMP head from a plurality of angles from below the CMP head104. The various images can be utilized by the control system108to detect damage to the CMP head104.

In one embodiment, the camera110is configured to capture images of the retainer ring132. The purpose of this is to enable the control system108to determine if the retainer ring132has been damaged during a planarization process. If the control system108detects damage to the retainer ring132, the control system108can stop operation of the CMP system until the retainer ring132has been replaced.

In one embodiment, the camera110may be positioned within the wafer load and unload unit106. For example, the camera110may be positioned in a gap138in the wafer load and unload unit106. While the camera110shown inFIG. 3Ais much larger than the gaps138, in practice, the camera110can be small enough to be positioned within the wafer load and unload unit106.

A CMP head104can include other components, arrangements of components, or structure other than not shown inFIG. 3Awithout departing from the scope of the present disclosure. In particular, a CMP head104may include various components for generating the pressure differential that holds a semiconductor wafer124within the gap134during CMP operations. Additionally, a wafer load and unload unit106may include other components, arrangements of components, or structure than shown inFIG. 3Awithout departing from the scope of the present disclosure.

FIG. 3Bis a bottom perspective view of the CMP head104ofFIG. 3A, according to one embodiment. The CMP head104includes a retaining ring132. The interior surface133of the retaining ring132laterally bounds the semiconductor wafer124(not shown inFIG. 3B) when the semiconductor wafer124is held by the CMP head104. The bottom surface135contacts the CMP pad116of a planarization station102(seeFIG. 2) during a CMP operation. The camera110may be positioned to capture images of the bottom surface135and the interior surface133of the retaining ring132.

The view ofFIG. 3Billustrates a damage location137on the interior surface133near where the interior surface133meets the bottom surface135. This is a common location for damage to occur to the retainer ring132. Accordingly, the camera110, or cameras110are able to capture images that focus on the interior surface133, the bottom surface135, or where the interior surface133meets the bottom surface135.

FIG. 4is a block diagram of a control system108, according to one embodiment. The control system108is part of a CMP system. The control system108can control components of the CMP system110to activate or deactivate CMP processes. The control system108is coupled to a camera108(seeFIGS. 1-3B) and this configured to receive images from the camera108. The control system108analyzes the images and controls the CMP system based on analysis of the images.

The control system108includes an image analyzer150and a control module156. The image analyzer receives input images152from the camera110. The image analyzer150analyzes the input images152and generates image classification data154based on analysis of the input images152. The control module156receives the image classification data154. If the image classification data indicates a problem with the CMP head104or component of the CMP head104such as the retainer ring132, then the control module156can cause the CMP system to pause or stop operation until repairs or replacements can be made.

As described previously, it can be difficult to detect damage to the retainer ring132with the human eye. The image analyzer150is capable of analyzing input images152of the retainer ring132with a much higher degree of detail than can the human eye. Due to the machine learning process, which is described in more detail below, the image analyzer150is able to detect very small differences between an image of a damaged retainer ring132and that image of a non-damaged retainer ring132. The image analyzer150can focus on the areas of the retainer ring132where damage is most likely to occur. For example, the image analyzer150can analyze images of the interior surface133of the retainer ring132, the area where the interior surface133meets the bottom surface135, the bottom surface135, or both the interior surface133and the bottom surface135. The image analyzer150can be trained to detect damage in any or all of these locations.

In one embodiment, the camera110captures images and the image analyzer150analyzes the images after each time the CMP head106unloads a wafer to the wafer load and unload unit106. In alternative embodiments, the process of capturing images in analyzing the images is performed only after the retainer ring132has surpassed a certain number of CMP processes. Damage is much more likely to occur later in a lifetime of the retainer ring132than at the beginning of the lifetime of the retainer ring132. Accordingly, the control system108can conserve processing resources by operating the camera110in the image analyzer150only after the retainer ring is been used enough times that damage is more likely to occur.

In one embodiment, the image analyzer150analyzes the input images152by comparing them to reference images158. The reference images158can include images of an undamaged CMP head. The reference images158can also include images of a damaged CMP head. The image analyzer150can compare the input images152to the reference images158to determine whether or not the input images152represents a damaged CMP head104. In one embodiment, the image classification data154indicates whether the input images152correspond to a damaged CMP head104. In other words, the classification data154classifies the input images as either “damaged” or “not damaged”.

In one embodiment, the image analyzer150is an analysis model trained with a machine learning process. The machine learning process trains the analysis model to correctly classify images of a CMP head (or retainer ring) as being damaged or not damaged. Accordingly, the image analyzer150can include a classifier model. The classifier model classifies input images in accordance with a machine learning process.

In one embodiment, the machine learning process is a supervised machine learning process. During the supervised machine learning process, the reference images158are used as a training set. The reference images158can be labeled as either “damaged” or “not damaged”. During the machine learning process, the reference images158are fed through the image analyzer150. The image analyzer150classifies the reference images158as either “damaged” or “not damaged”. The classifications are compared to the labels. After comparison to the labels, parameters of an internal algorithm or function are adjusted and the reference images150are again passed through the image analyzer150. This process is repeated in iterations until the image classifier150can reliably generate image classification data154that matches the labels on the reference images158.

In one embodiment, the image analyzer150includes a neural network. The neural network includes a plurality of neural layers. The neuron layers correspond to a weighted function. The input images152are passed to a first neural layer. The first neural layer processes the input images152in accordance with a series of weighted values. The weighted values are determined in iterations during the machine learning process, as described above. The process data is passed to the next neural layer which again processes the data. This process proceeds until a final neural layer outputs classification data154. The classification data154indicates whether the input images correspond to a “damaged” or “not damaged” CMP head.

In one embodiment, the image analyzer150includes a convolutional neural network. The convolutional neural network is a deep learning neural network. The convolutional neural network is configured to analyze the input images152and classify them as either “damaged” or “non-damaged”. The convolutional neural network includes a plurality of convolutional layers, a plurality of rectifier layers, a plurality of pooling layers, and one or more fully connected layers. During operation of the convolutional neural network, a first convolutional layer receives data corresponding to the input image. The input image may be formatted for processing by the convolutional layer prior to reaching the convolutional layer. The first convolutional layer then performs a convolution operation on the input image. The rectifier layer may perform rectifying operations on the data from the first convolution layer. A pooling layer then performs pooling operations on the (rectified) data from the convolution operation. After the pooling operation, the data is passed to a next convolutional layer in the process of convolution, rectification, and pooling operations repeats. This process continues until the data is provided to one or more fully connected layers. Fully connected layers indicate that the layer has the same number of neurons as the previous layer such that each neuron in the fully connected layer is fully connected to a neuron from the previous layer. A final fully connected layer generates image classification data154. The image classification data154classifies the input image as “damaged” or “not damaged”.

While some examples of machine learning models and processes have been described above, an image analyzer150can include other types of machine learning models, training processes, or other image analysis techniques without departing from the scope of the present disclosure.

The control system108can include one or more memories that store software instructions or image analysis algorithms or processing data. The control system108can include one or more processors configured to execute instructions or to process input images in accordance with the processing data stored in the memories.

FIG. 5is a flow diagram of a process500for training an analysis model, such as the image analyzer150ofFIG. 4, to accurately predict future VOC removal efficiency, according to one embodiment. The various steps of the process500can utilize components, processes, and techniques described in relation toFIGS. 1-4. Accordingly,FIG. 5is described with reference toFIGS. 1-4.

At502, the process500gathers training set data including and historical retainer ring images and historical classification data. This can be accomplished by using a data mining system or process. The data mining system or process can gather training set data by accessing one or more databases associated with the CMP system and collecting images of damaged and undamaged retainer rings. The data mining system or process, or another system or process, can process and format the collected data in order to generate a training set data.

At504, the process500inputs historical retainer ring images to the analysis model of the image analyzer150. In one example, this can include inputting historical retainer ring images into the analysis model. The historical retainer ring images can be provided in consecutive discrete sets to the analysis model of the image analyzer150.

At506, the process500generates predicted classification data based on historical retainer ring images. In particular, the analysis model generates, for each set of historical retainer ring images, predicted classification data. The predicted classification data classifies each image as representing either a damaged retainer ring or an undamaged retainer ring.

At508, the predicted classification data is compared to the historical classification data. In particular, the predicted classification data for each set of historical retainer ring images is compared to the historical classification data associated with that set of historical retainer ring images. The comparison can result in an error function indicating how closely the predicted classification data matches the historical classification data. This comparison is performed for each set of predicted classification data. In one embodiment, this process can include generating an aggregated error function or indication indicating how the totality of the predicted classification data compares to the historical classification data. The comparisons can include other types of functions or data than those described above without departing from the scope of the present disclosure.

At510, the process500determines whether the predicted classification data matches the historical classification data based on the comparisons generated at step508. In one example, if the aggregate error function is greater than an error tolerance, then the process500determines that the predicted classification data does not match the historical classification data. In one example, if the aggregate error function is less than an error tolerance, then the process500determines that the predicted classification data does match the historical classification data.

In one embodiment, if the predicted classification data does not match the historical classification data at step510, then the process proceeds to step512. At step512, the process500adjusts the internal functions associated with the analysis model. From step512, the process returns to step504. At step504, the historical retainer ring images are again provided to the analysis model. Because the internal functions of the analysis model of the image analyzer150have been adjusted, the analysis model will generate different predicted classification data than in the previous cycle. The process proceeds to steps506,508and510and the aggregate error is calculated. If the predicted classification data does not match the historical classification data, then the process returns to step512and the internal functions of the analysis model of the image analyzer150are adjusted again. This process proceeds in iterations until the analysis model of the image analyzer150generates predicted classification data that matches the historical classification data.

In one embodiment, if the predicted classification data matches the historical classification data at process step510, then the process500, proceeds to514. At step514training is complete. The analysis model of the image analyzer150of the analysis model is now ready to be utilized to detect whether a retainer ring is damaged after a CMP process. Steps502-514correspond to a machine learning process for the analysis model.

After the analysis model is trained, the process500proceeds to516. At516, a wafer is loaded into the CMP head104. The wafer can be loaded into the CMP head one or from a wafer load and unload unit106, as described previously in relation toFIGS. 1-4. At518, a CMP system performs a CMP process on the wafer with the CMP head. The CMP process can be performed substantially as described in relation toFIGS. 1 and 2.

At520, after the CMP process has been performed, the wafer is unloaded from the CMP head104into the wafer load and unload unit106. The wafer can be loaded from the CMP head104into the wafer load and unload unit106substantially as described in relation toFIGS. 1-4.

At522, the camera110captures images of the retainer ring132of the CMP head104. The camera110can capture images of the retainer ring132substantially as described in relation toFIGS. 1 to 4.

At524, the analysis model analyzes the images captured by the camera110. The analysis model classifies the retainer ring is damaged or not damaged based on the analysis of the images. Because the analysis model has been trained with a machine learning process as described in relation to steps502-514, the analysis model can reliably determine whether the retainer ring is damaged or not damaged.

At526, if the retainer ring132is damaged, then the control module156of the control system108outputs an alert indicating that the retainer ring132is damaged. The control system102also shuts down the CMP process until the retainer ring132can be replaced.

The process500can include other steps or arrangements of steps than shown and described herein without departing from the scope of the present disclosure.

FIG. 6is a flow diagram of a method600for operating a chemical mechanical planarization system, according to one embodiment. At602, the method600includes receiving a first semiconductor wafer with a chemical mechanical planarization head of a chemical mechanical planarization system. One example of a chemical mechanical planarization head is the chemical mechanical planarization head104ofFIG. 1. At604, the method600includes performing a chemical mechanical planarization process on the first semiconductor wafer. At606, the method600includes passing the first semiconductor wafer from the chemical mechanical planarization head to a wafer load and unload unit after the chemical mechanical planarization process. One example of a wafer load and unload unit is the wafer load and unload unit106ofFIG. 1. At608, the method600includes capturing an image of the chemical mechanical planarization head after passing the first wafer to the wafer load and unload unit. At610, the method600includes analyzing the image with a control system. One example of a control system is the control system108ofFIG. 1. At612, the method600includes determining whether to provide a second semiconductor wafer to the chemical mechanical planarization head based on the image.

FIG. 7is a flow diagram of a method700for operating a CMP system, according to one embodiment. At702, the method700includes performing a chemical mechanical planarization process on a first semiconductor wafer held by a chemical mechanical planarization head. One example of a chemical mechanical planarization head is the chemical mechanical planarization head104ofFIG. 1. At704, the method700includes unloading the first semiconductor wafer from the chemical mechanical planarization head to a wafer load and unload unit. One example of a wafer load and unload unit is the wafer load and unload unit106ofFIG. 1. At706, the method700includes capturing an image of a retainer ring of the chemical mechanical planarization head after unloading the first semiconductor wafer. One example of a retainer ring is the retainer ring132ofFIGS. 3A and 3B. At708, the method700includes detecting, with a control system, that the retainer ring is damaged based on the image. One example of a control system is the control system108ofFIG. 1. At710, the method700includes stopping, with the control system, operation of the chemical mechanical planarization head responsive to detecting that the retainer ring is damaged.

One embodiment is a method including receiving a first semiconductor wafer with a chemical mechanical planarization head of a chemical mechanical planarization system and performing a chemical mechanical planarization process on the first semiconductor wafer. The method includes passing the first semiconductor wafer from the chemical mechanical planarization head to a wafer load and unload unit after the chemical mechanical planarization process and capturing an image of the chemical mechanical planarization head after passing the first wafer to the wafer load and unload unit. The method includes analyzing the image with a control system and determining whether to provide a second semiconductor wafer to the chemical mechanical planarization head based on the image.

One embodiment is a method including performing a chemical mechanical planarization process on a first semiconductor wafer held by a chemical mechanical planarization head and unloading the first semiconductor wafer from the chemical mechanical planarization head to a wafer load and unload unit. The method includes capturing an image of a retainer ring of the chemical mechanical planarization head after unloading the first semiconductor wafer and detecting, with a control system, that the retainer ring is damaged based on the image. The method includes stopping, with the control system, operation of the chemical mechanical planarization head responsive to detecting that the retainer ring is damaged.

One embodiment is a chemical mechanical planarization system including a chemical mechanical planarization station configured to perform a chemical mechanical planarization process. The system includes a wafer load and unload unit configured to receive a semiconductor wafer. The system includes a chemical mechanical planarization head configured to receive the semiconductor wafer from the wafer load and unload unit, to carry the semiconductor wafer to the chemical mechanical planarization station for the chemical mechanical planarization process, and to return the semiconductor wafer to the wafer load and unload unit. The system includes a camera configured to capture an image of the chemical mechanical planarization head after the chemical mechanical planarization head has returned the semiconductor wafer to the wafer load and unload unit. The system includes a control system configured to receive the image, to analyze the image with an image analysis process, to generate a classification of the image, and to control the chemical mechanical planarization head responsive to the classification.

Embodiments of the present disclosure provide many benefits over traditional chemical mechanical planarization systems. Embodiments of the present disclosure utilize an image capturing system and machine learning techniques to detect damage or other flaws in chemical mechanical planarization equipment before the equipment can damage a semiconductor wafer. Embodiments of the present disclosure reduce the need for technicians or experts to stop operation of the chemical mechanical planarization equipment in order to manually inspect chemical mechanical planarization equipment. Instead, the image capture system and machine learning modules can detect damaged equipment during operation and can automatically stop operation if damage is detected. The result is that fewer resources are utilized in inspecting and operating chemical mechanical planarization equipment. Furthermore, fewer expensive semiconductor wafers will need to be scrapped due to damaged chemical mechanical planarization equipment.