Pad Conditioner and Chemical Mechanical Planarization Apparatus

This application claims priority to Chinese Patent Application No. 202421293222.2, filed on Jun. 6, 2024, which is hereby incorporated by reference in its entirety.

The present application relates to the field of chemical mechanical planarization apparatus, and in particular to a pad conditioner and a chemical mechanical planarization apparatus.

Chemical Mechanical Planarization (CMP) is a critical process in integrated circuit manufacturing for achieving wafer surface planarization. The primary working principle of CMP is that under a certain pressure and in the presence of a polishing liquid, the wafer makes a relative motion against the polishing pad. With the aid of highly integrated combination between the mechanical polishing action of nano-abrasives and the chemical action of various types of chemical reagents, the surface of the wafer may achieve requirements of a high planarization, low surface roughness and low defects. After CMP, by-products such as particles solidified by the polishing liquid are left on the polishing pad, and these residual by-products may affect the subsequent wafer polishing process, thus affecting the yield of wafer. Therefore, it is necessary to use a pad conditioner (PC) to condition the surface of the polishing pad regularly. The pad conditioner is typically integrated into the CMP apparatus. When conditioning of the polishing pad is not required, there is a certain distance between the conditioning disk, which is used to condition the surface of the grinding pad in the PC, and the polishing pad. When conditioning of the polishing pad is required, the conditioning disk is lowered to bring the conditioning disk into contact with the polishing pad, and the conditioning disk is driven to rotate so as to clean the polishing pad.

However, in the process of conditioning the polishing pad by the pad conditioner, the pressure of the conditioning disk against the polishing pad is difficult to be detected in time. And if the pressure deviates, it may affect the conditioning effect of the polishing pad, which may in turn affect the polishing rate of the wafer in the subsequent polishing process, further affecting the yield of wafer. Therefore, there is an urgent need for an optimized pad conditioner that can detect the pressure of the conditioning disk against the polishing pad in time during the conditioning process to avoid damage to the polishing pad.

According to various embodiments of the present application, one aspect of the present application provides a pad conditioner, comprising: a swing arm; an adjusting assembly, disposed at one end of the swing arm and comprising an airtight chamber; a conditioning disk, disposed on one side of the adjusting assembly that is away from the swing arm, wherein the adjusting assembly is configured to drive the conditioning disk to move in a direction towards or away from the adjusting assembly by deformation of the airtight chamber; a pressure detecting unit, embedded in the airtight chamber and configured to detect an internal gas pressure within the airtight chamber; and a control unit, configured to receive the internal gas pressure and determine a working state of the pad conditioner based on the internal gas pressure.

Another aspect of the present application provides a chemical mechanical planarization apparatus comprising a pad conditioner and a polishing pad, wherein the pad conditioner is configure to condition the polishing pad, and the pad conditioner comprises: a swing arm; an adjusting assembly, disposed at one end of the swing arm and comprising an airtight chamber; a conditioning disk, disposed on one side of the adjusting assembly that is away from the swing arm, wherein the adjusting assembly is configured to drive the conditioning disk to move in a direction towards or away from the adjusting assembly by deformation of the airtight chamber; a pressure detecting unit, embedded in the airtight chamber and configured to detect an internal gas pressure within the airtight chamber; and a control unit, configured to receive the internal gas pressure and determine a working state of the pad conditioner based on the internal gas pressure.

In order to facilitate an understanding of the present application, the present application will be described more fully below with reference to the relevant accompanying drawings. Embodiments of the present application are given in the accompanying drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the content of the present application more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the field to which the present application belongs. Terms used herein in the specification of the present application are used only for the purpose of describing specific embodiments and are not intended to limit the present application.

In the case of using “including,” “having,” and “comprising” as described herein, unless explicitly limited by terms such as “only” or “consisting of,” additional components may be added. Unless otherwise stated, singular forms of terms may include plural forms and should not be interpreted as being limited to a single item.

In the description of the present application, it should be noted that unless otherwise explicitly defined and limited, the terms “connect to” or “connect with” should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can refer to internal communication between two components. For those skilled in the art, the specific meaning of the aforementioned terms in the present application can be understood based on the context.

When used herein, the singular forms “a,” “an,” and “the” may also include plural forms unless the context clearly dictates otherwise. It should also be understood that terms such as “include”/“comprise,” or “have” specify the presence of the stated features, entirety, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, entireties, steps, operations, components, parts, or combinations thereof. Additionally, the term “and/or” as used in this specification includes any and all combinations of the listed related items.

Chemical mechanical planarization (CMP) is important in modern semiconductor manufacturing. Chemical mechanical planarization combines both chemical etching and mechanical polishing to remove uneven materials on the wafer surface structure and flatten the wafer surface structure on an atomic-level. The polishing pad in chemical mechanical planarization apparatus needs to be replaced in time and maintained regularly, and the newly replaced polishing pad, due to its high hardness, also needs to go through a period of running-in to achieve the ideal surface texture, thereby realizing the polishing efficiency and uniformity. There are numerous factors that affect polishing effect, such as composition of polishing liquid, etching rate, a type of abrasive particulate material, material, hardness, elasticity modulus, and surface wear of polishing pad, temperature, pressure, rotation speed, and nonlinear hydrodynamics in the polishing process.

As shown in, as an example, during chemical mechanical planarization, the wafer being polished (not shown) is forced to move relative to the grinding pad, while the polishing liquid is continually dripped onto the polishing padto remove the material on the wafer surface that needs to be removed after reacting mildly with the chemical components in the polishing liquid. During the polishing process, byproducts, such as particles solidified from the polishing liquid, may remain in the grooves on the surface of the polishing pad. These residual byproducts can affect subsequent wafer polishing processes, thereby impacting the yield of wafer. Therefore, a pad conditionercan be used periodically to condition the surface of the polishing pad, preventing the polishing byproducts from filling the grooves of the polishing pad. The pad conditioneris generally integrated into the CMP apparatus, and includes a swing armand a conditioning disk. When there is no need to condition the polishing pad, the conditioning diskis kept from the surface of the polishing padby a certain distance; and when the polishing padneeds to be conditioned, the conditioning diskis lowered to allow the conditioning diskto come into contact with the surface of the polishing pad. A pressure can be applied by the pad conditioner, causing relative motion between the conditioning diskand the polishing padfor removing the byproducts on the polishing pad, thereby conditioning the polishing pad.

As shown in, the pad conditionerin the chemical mechanical planarization apparatus is used to condition and adjust the polishing pad, to roughen the surface of the polishing padand to flatten the polishing pad, so as to polish the wafer uniformly. The pad conditionercan condition the surface of the polishing padby the conditioning diskof the pad conditioner. During the process of conditioning the surface of the polishing padby the conditioning disk, the conditioning pressure of the conditioning diskonto the polishing pad(i.e., the interaction force between the conditioning diskand the polishing padduring the conditioning process) is a critical factor influencing the conditioning effect on the surface of the polishing pad. Maintaining a stable and controllable conditioning pressure of the conditioning diskcan benefit the conditioning effect.

Currently, the conditioning pressure fed back by the chemical mechanical planarization apparatus is provided by a cleaning system integrated within the planarization apparatus. The conditioning pressure is not a true conditioning pressure and the CMP apparatus is not capable of detecting the true conditioning pressure in time and accurately. Additionally, as shown in, a conventional method for detecting the conditioning pressure is: usually, during maintenance of the CMP apparatus, a maintenance engineer uses a pressure measuring instrument, and connects a handleof the pressure measuring instrument to a pressure meter, the pressure meteris used to sense a downward pressure exerted by the conditioning diskof the pad conditionerduring operation and transmit a pressure result to the handleof the pressure measuring instrument, thereby achieving the measurement and calibration of the conditioning pressure of the conditioning disk. However, the pressure detected by this measurement method is not the actual conditioning pressure exerted by the conditioning disconto the polishing padduring the conditioning process, and also the detecting method increases labor costs. Therefore, when the conditioning pressure of the conditioning diskonto the polishing paddeviates during the conditioning process, it is difficult for conventional technologies to identify the abnormal pressure timely. This often results in scratcheson the polishing padas shown in), causing wafer damage and further affecting the yield of wafer.

Based on this, it is necessary to provide a pad conditioner and a chemical mechanical planarization apparatus to solve the problems mentioned above, which can detect the pressure change of the polishing conditioner against the polishing pad in time in the process of conditioning the polishing pad, identify abnormal pressure in time, reduce the probability of damage to the polishing pad, and avoid the damage to the wafer product.

As shown in, embodiments of the present application provide a pad conditioner. The pad conditionermay include a swing arm, an adjusting assembly, a conditioning disk, a pressure detecting unit, and a control unit. The adjusting assemblymay be disposed at one end of the swing arm, and the adjusting assemblyincludes an airtight chamber. The conditioning diskmay be disposed on one side of the adjusting assemblythat is away from the swing arm, and the adjusting assemblyis configured to drive the conditioning diskto move in a direction towards or away from the adjusting assemblyby deformation of the airtight chamber. The pressure detecting unitmay be embedded in the airtight chamberand is configured to detect an internal gas pressure within the airtight chamber. The control unitmay be configured to receive the internal gas pressure and to determine a working state of the pad conditioner.

In some embodiments, the adjusting assemblydrives the conditioning diskto move in a direction towards or away from the adjusting assemblyby the deformation of the airtight chamber. In other words, a change in displacement of the conditioning diskin the direction towards or away from the adjusting assemblyalso results in the deformation of the airtight chamber, and thus changes the internal gas pressure within the airtight chamber. Thus, by detecting the internal gas pressure within the airtight chamberthrough the pressure detecting unitembedded in the airtight chamberof the pad conditioner, the control unitmay be configured to receive the internal gas pressure within the airtight chamberand determine the working state of the pad conditionerbased on the internal gas pressure. The accurate measurement and timely adjustment of the conditioning pressure of the conditioning diskonto the pad conditionermay be realized, avoiding the interference of human factors in the measurement, realizing in-time detection and accurate measurement, avoiding abnormal conditioning pressure leading to damage to the polishing pad, thereby avoiding damage to the wafer product and reducing the labor cost of detection.

In some embodiments, as shown in, the adjusting assemblymay further include a cylinder, a supporting component, a central shaftand a gas film. The cylindermay be connected to the swing arm. The supporting componentmay be disposed within the cylinder, extending along an axial direction of the adjusting assembly(e.g., extension direction of axis x in). One endof the central shaftthat is close to the swing armis slidably connected to the supporting component, and the other endof the central shaftthat is away from the swing armmay extend out of the cylinderand may be connected to the conditioning disk. The central shaftis configured to drive the conditioning diskto move in a direction towards or away from the adjusting assembly(e.g., z direction in). The gas filmmay be annular in shape and disposed within the cylinder. The gas filmincludes an outer edgeand an inner edge. The outer edgeof the gas filmmay be fixedly connected to an inner wall of the cylinder, and the inner edgeof the gas filmmay be fixedly connected to an outer wall of the central shaft. In some embodiments, the airtight chambermay be formed by the gas film, together with the cylinder, the central shaftand the supporting component.

In some embodiments, please continue to refer to, one end of the cylinderthat is close to the swing armmay be provided with an opening, and a rotating componentmay be arranged at the opening. The rotating componentcan drive the supporting componentto rotate around the axis of the adjusting assembly(e.g., extension direction of axis x in). The outer edgeof the gas filmmay be fixedly connected to the rotating component. In these embodiments, the airtight chambermay be formed by the gas film, tighter with the rotating component, the central shaftand the supporting component.

Please continue to refer to, a motor (not shown) may be provided on the swing arm, and the rotation of the motor may drive the rotating componentto rotate synchronously, thereby reducing the wiring complexity of the pressure detecting unit.

In some embodiments, please continue to refer to, the rotating componentmay be provided with an inlet. The inletis configured to introduce a gas into the airtight chamberor extract gas from the airtight chamberso as to drive the gas filmto deform, which in turn drives the central shaftto move in a direction towards or away from the swing arm(e.g., z-direction in).

In some embodiments, please continue to refer to, the pad conditionermay be further provided with a gas pipe. One end of the gas pipethat is close to the adjusting assemblymay be communicated with the inlet, and the other end of the gas pipemay be communicated with an external gas source (not shown).

In some embodiments, as shown in, the pad conditioner may include a pressure detecting unitand a converter. The pressure detecting unitmay be embedded within the airtight chamberof the pad conditionerand is configured to detect the internal gas pressure within the airtight chamber. As described above, the expansion or contraction of the gas filmdrives the central shaftto move in the direction towards or away from the swing arm, and thus drives the conditioning diskto move in the direction towards or away from the swing arm, thereby changing a distance of the conditioning diskwith respect to the polishing pad(as shown in). During the conditioning process of the polishing padby the conditioning disk, the conditioning pressure of the conditioning diskgenerally remains constant. Once the conditioning pressure changes, the conditioning diskmay be displaced in a direction towards or away from the swing arm, which in turn causes the gas filmto expand or contract, thereby affecting the internal gas pressure within the airtight chamber. The pressure detecting unitmay be sealed within the airtight chamberand connected to the converter. There is a relationship between the conditioning pressure of the conditioning diskand the internal gas pressure within the airtight chamber. The relationship may be, for example, linear. The pressure detecting unitmay use this relationship to convert the internal gas pressure within the airtight chamberinto a detection pressure value corresponding to the conditioning pressure of the conditioning disk. In this way, embodiments of the present application may obtain a more accurate detection pressure value corresponding to the actual conditioning pressure compared to traditional detection methods, and may achieve in-time monitoring of the conditioning pressure, avoiding human interference in the measurement, reducing the likelihood of damage to the polishing pad, and lowering the labor costs associated with detection.

Please continue to refer to, the pad conditioner may further include a control unitand an alarm. The control unitmay be connected to the converterand used to generate an alarm command when the detection pressure value falls out of a preset pressure range. For instance, the preset pressure range may be a target pressure value±0.3 pounds-force, wherein the target pressure value may be a conditioning pressure of the conditioning diskunder normal working condition. When the detection pressure value obtained by the converterexceeds the preset pressure range, an alarm command may be automatically generated. The alarmmay be connected to the control unitand is configured to receive the alarm command and execute a corresponding alarm action. For example, the alarm action can be set to shut down the CMP apparatus. In this way, any abnormality in the conditioning pressure of the conditioning diskcan be timely detected, and the chemical mechanical planarization apparatus can be stopped and thus reduces the likelihood of damage to the polishing pador the wafer product.

In some embodiments, please continue to refer to, the detection pressure value outputted by the convertercan be transmitted to the control unit, to generate a pressure graph. The pressure graph can be a line graph, a dot graph or a chart, making the detection results visualized. Furthermore, the pad conditioner can further include a display. The displaycan be connected to the converterand used to receive and display the detection pressure value and/or the pressure graph formed by the converter. Therefore, an operator of the pad conditioner can monitor the conditioning pressure of the conditioning diskin time and identify the abnormal pressure condition promptly.

As an example, please continue to refer to, the alarmmay include a switch. The switchmay be connected to the control unit. The switchmay be connected in series with the pad conditioner and a power supply, so that the switchcan receive the alarm command and disconnect an electrical connection between the pad conditioner and the power supply, thereby preventing damage to the polishing pad and enabling timely inspection of the pad conditioner.

As an example, please continue to refer to, the convertermay include a proportional valve, and the proportional valvemay be connected to the pressure detecting unit. The proportional valveis used to generate the detection pressure value by the received internal gas pressure within the airtight chamber. The proportional valvemay be an electro-pneumatic proportional valve.

As an example, the pressure detecting unitmay include a gas pressure sensor, and the gas pressure sensor may be embedded in the airtight chamber of the pad conditioner and used to detect the internal gas pressure within the airtight chamber.

In some embodiments, the gas pressure sensor may include a housing, a pressure chip, and a diaphragm. The housing may be internally provided with a cavity and externally provided with a mounting portion. The mounting portion is used to attach the housing to the airtight chamber. The pressure chip may be encapsulated within the cavity. The diaphragm may be located on one side of the pressure chip that is away from the mounting portion of the housing, and the diaphragm is used to seal the pressure chip and transmit the internal gas pressure within the airtight chamber to the pressure chip, thereby achieving the precise measurement of the conditioning pressure.

In some embodiments, the pressure chip may include a diffused silicon pressure-sensitive chip. Agas pressure sensor equipped with a diffused silicon pressure-sensitive chip could measure a small-range pressure and have high sensitivity and high measurement accuracy.

In some embodiments, the connection between the gas pressure sensor and the airtight chamber may be sealed with a sealing ring to ensure the accuracy of pressure measurement.

In some embodiments, the cavity of the housing may be filled with a buffer fluid sealed within the cavity and located between the diffused silicon pressure-sensitive chip and the diaphragm. The buffer fluid is configured to transmit, to the pressure chip, the internal gas pressure within the airtight chamber formed on the diaphragm.

In some embodiments, the housing of the gas pressure sensor may be made by 316L stainless steel. The diaphragm is made by stainless steel or ceramic. The buffer fluid may include silicone oil. By encapsulating the diffused silicon pressure-sensitive chip into a 316L stainless steel housing and sealing the silicone oil into the cavity by the stainless steel diaphragm, the applied external pressure can be transmitted to the pressure-sensitive chip through the stainless steel diaphragm and the internally sealed silicone oil, and a fully solid-state structure for pressure measurement is formed. The pressure-sensitive chip may not come into direct contact with the measured medium, which may help the pressure-sensitive chip to achieve a precise pressure measurement.

Another aspect of embodiments of the present application provides a chemical mechanical planarization apparatus, which includes a pad conditioner and a polishing pad. The pad conditioner is configured to condition the polishing pad, and the pad conditioner is as described in any one of the aforementioned embodiments.

Exemplarily, when the pad conditioner in the chemical mechanical planarization apparatus conditions the polishing pad of the chemical mechanical planarization apparatus, a gas pressure within the airtight chamber can be detected by the pressure detecting unit which embedded in the airtight chamber. The converter that connected to the pressure detecting unit receives the gas pressure within the airtight chamber and converts it into a detection pressure value corresponding to the conditioning pressure of the conditioning disk to the polishing pad. When the detection pressure value exceeds a preset pressure range, an alarm command is automatically generated. The alarm of the pad conditioner receives the alarm command and executes a corresponding alarm action, so as to detect any abnormality in the conditioning pressure in time and shut down the chemical mechanical planarization apparatus. The display of the pad conditioner receives and displays the detection pressure value. Additionally, the in-time monitoring of the conditioning pressure is achieved, which may ensure timely detection of abnormal conditioning pressure, achieve precise measurement, eliminating human interference in the measurement, preventing damage to the polishing pad due to abnormal pressure, and thus avoiding damage to wafer products while reducing labor costs of detection.

In the description of this specification, references to terms such as “some embodiments” or “other embodiments” mean that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the illustrative descriptions of these terms do not necessarily refer to the same embodiment or example.

The technical features of the embodiments described above can be combined in any manner. To keep the description concise, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combinations of these technical features do not contradict each other, they should all be considered within the scope of this specification.

The embodiments described above illustrate only several implementation modes of the present application, and their descriptions are relatively specific and detailed. Nevertheless, this should not be interpreted as a limitation on the scope of the present application. It should be noted that for those skilled in the art, various modifications and improvements can be made without departing from the concept of the present application, and all of them fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.