Polishing Apparatus and Polishing Method

The present application claims priority to Chinese Application No. 202410341620.5, filed on Mar. 22, 2024, which is hereby incorporated by reference in its entirety.

The present application relates to the technical field of semiconductors and, in particular, to a polishing apparatus and a polishing method.

With the rapid development of semiconductor integrated circuit manufacturing technology, chemical-mechanical polishing (CMP) technology is more and more widely used. Chemical-mechanical polishing technology can perform a planarization treatment on a surface of a wafer, avoiding fluctuation of the surface of the wafer, and providing a flat interface for the subsequent process. Thus, a polishing apparatus used in the chemical-mechanical polishing has become one of the important pieces of the apparatus in semiconductor processes.

The polishing apparatus includes a polishing table, a polishing pad disposed on the polishing table, a polishing head disposed above the polishing pad and a pad conditioner (PC). Where, the polishing head sucks and fixes the wafer, and the surface of the wafer is in contact with the polishing surface of the polishing pad and moves relative to the polishing pad at a certain pressure and rotation speed for polishing. Meanwhile, polishing liquid continuously drops on the polishing pad, and the polishing effect is achieved under the dual effects of physical mechanical and chemical actions. The pad conditioner regularly polishes and tunes the surface of the polishing pad to adjust the flatness of the polishing pad, thereby maintaining the polishing performance of the polishing pad to control the surface morphology of the wafer.

However, the existing pad conditioner has a poor tuning effect on the polishing pad, and it is easy to damage the polishing pad, for example, the polishing pad could be worn out, and the wafer is thereby scratched or damaged.

In view of the above problems, embodiments of the present application provide a polishing apparatus and a polishing method to improve the tuning effect of a pad conditioner on a polishing pad.

In order to achieve the above object, a first aspect of the embodiments of the present application provides a polishing apparatus, including: a polishing pad, a movable pad conditioner, a cleaning nozzle, a pressure detecting unit provided on the cleaning nozzle, and a control unit; the pad conditioner is movable on the pressure detecting unit and in contact with the pressure detecting unit, and the pad conditioner is configured to tune the polishing pad; the pressure detecting unit is configured to measure pressure data of the pad conditioner; the cleaning nozzle is configured to clean the pad conditioner; and the control unit is electrically coupled with both the pad conditioner and the pressure detecting unit, and sets a working state of the pad conditioner according to the pressure data; where the control unit is configured to acquire the pressure data of the pad conditioner when the cleaning nozzle cleans the pad conditioner.

In some possible embodiments, the pressure detecting unit further includes: a hollow base, provided on the cleaning nozzle; and a pressure sensing element, disposed at one end of the hollow base away from the cleaning nozzle, the pressure sensing element being configured to sense the pressure data.

In some possible embodiments, the pressure sensing element further includes a pressure sensing ring, and a shape of the pressure sensing ring is the same as that of one end of the hollow base away from the cleaning nozzle.

In some possible embodiments, the pressure sensing ring further includes a conductive material layer, a spacer layer and a pressure-sensitive material layer disposed in a stacked manner, where a material of the spacer layer includes a polyester material.

In some possible embodiments, where the pressure sensing element further includes a plurality of supporting legs which are disposed at intervals and are all disposed between the pressure sensing ring and the hollow base.

In some possible embodiments, where the plurality of supporting legs and the pressure sensing ring are an integral structure, and a material of the plurality of supporting legs includes a flexible material.

In some possible embodiments, the pad conditioner further includes: a tuning base, a surface of which has a central area and an edge area surrounding the central area, a shape of the edge area corresponding to a shape of the pressure sensing ring; and tuning particles, disposed in the central area.

In some possible embodiments, where the hollow base further includes a tubular structure, a plurality of cleaning nozzles are provided, and the tubular structure is provided outside at least one cleaning nozzle.

In some possible embodiments, where the hollow base further includes an outer edge, the outer edge is disposed on a radial side wall of one end of the tubular structure facing the pad conditioner, and a surface of the outer edge facing the pad conditioner is on a same level with a surface of the tubular structure facing the pad conditioner.

In some possible embodiments, the control unit is configured to: in response to the pressure data being out of a preset pressure range, set the pad conditioner in an idle state; and in response to the pressure data being within the preset pressure range, set the pad conditioner in a polishing state; and where in response to the pad conditioner being in a polishing state, the pad conditioner performs at least one tuning on the polishing pad.

The polishing apparatus provided in the embodiments of the present application includes a polishing pad, a pad conditioner, a cleaning nozzle, a pressure detecting unit and a control unit, where the pad conditioner can be moved onto the pressure detecting unit and contact with the pressure detecting unit, the pressure detecting unit is used to measure a pressure data of the pad conditioner, the cleaning nozzle is used to clean the pad conditioner, and the control unit is electrically connected with both the pad conditioner and the pressure detecting unit, and controls a working state of the pad conditioner according to the pressure data. Use of the pressure detecting unit to monitor the pressure of the pad conditioner prevents the polishing pad from being damaged by an excessively large pressure of the pad conditioner or a by-product on the polishing pad from being difficult to be removed due to an excessively small pressure of the pad conditioner, thus ensuring the tuning effect. Compared with manual measurement and calibration, it can ensure the accuracy of measurement, reduce interference of human factors, reduce the occupation of labor hours and reduce labor costs.

A second aspect of the embodiments of the present application provides a polishing method, which is applied to the polishing apparatus as mentioned above, and the polishing method includes: step a, moving a pad conditioner of the polishing apparatus towards a pressure detecting unit and to contact with the pressure detecting unit, wherein the pressure detecting unit is provided on a cleaning nozzle of the polishing apparatus, and in response to the cleaning nozzle cleaning the pad conditioner, obtaining pressure data of the pad conditioner; step b, setting a working state of the pad conditioner according to the pressure data and a preset pressure range; and sequentially repeating the step a and step b until the pad conditioner finishes tuning for a polishing pad of the polishing apparatus or the pad conditioner is in an idle state.

In some possible embodiments, where setting the working state of the pad conditioner according to the pressure data and the preset pressure range includes: in response to the pressure data being out of the preset pressure range, setting the pad conditioner in an idle state; and in a response to the pressure data being within the preset pressure range, setting the pad conditioner in a polishing state; and in response to the pad conditioner being in a polishing state, performing, by the pad conditioner, at least one tuning on the polishing pad.

In the polishing method in the embodiments of the present application, the pressure data of the pad conditioner is obtained by controlling the pad conditioner to reach the pressure detecting unit and contact with the pressure detecting unit, and the working state of the pad conditioner is controlled according to the pressure data and the preset pressure range. The pressure data measurement of the pad conditioner and the control process of the working state of the pad conditioner are sequentially repeated until the pad conditioner finishes tuning of the polishing pads or the pad conditioner is in an idle state, so as to ensure that the pressure of the pad conditioner during tuning is within a normal range, avoiding damage to the polishing pad due to excessively large pressure of the pad conditioner or difficulty in removal of by-products on the polishing pad due to an excessively small pressure of the pad conditioner, thereby ensuring the tuning effect. In addition, by using the pressure detecting unit to obtain the pressure data of the pad conditioner, the cleaning nozzle can simultaneously clean the pad conditioner, thereby reducing the movement of the pad conditioner and reducing the complexity of the operation.

A third aspect of the embodiments of the present application provides a wafer processing system including a polishing pad, a movable pad conditioner, a cleaning nozzle, a pressure detecting unit provided on the cleaning nozzle, and a control unit; where the polishing pad is configured to polish the wafer; the pad conditioner is movable on the pressure detecting unit and in contact with the pressure detecting unit; the pressure detecting unit is configured to measure pressure data of the pad conditioner; the cleaning nozzle is configured to clean the pad conditioner; and the control unit is electrically coupled with both the pad conditioner and the pressure detecting unit, and sets a working state of the pad conditioner according to the pressure data; where the control unit is configured to acquire the pressure data of the pad conditioner when the cleaning nozzle cleans the pad conditioner.

In some possible embodiments, the pressure detecting unit further includes: a hollow base, provided on the cleaning nozzle; and a pressure sensing element, disposed at one end of the hollow base away from the cleaning nozzle, the pressure sensing element being configured to sense the pressure data.

In some possible embodiments, the pressure sensing element further includes a pressure sensing ring, and a shape of the pressure sensing ring is same as that of one end of the hollow base away from the cleaning nozzle.

In some possible embodiments, the pressure sensing ring further includes a conductive material layer, a spacer layer and a pressure-sensitive material layer disposed in a stacked manner, where a material of the spacer layer comprises a polyester material.

In some possible embodiments, the pressure sensing element further includes a plurality of supporting legs, which are disposed at intervals and are all disposed between the pressure sensing ring and the hollow base.

In some possible embodiments, the plurality of supporting legs and the pressure sensing ring are an integral structure, and a material of the plurality of supporting legs includes a flexible material.

In some possible embodiments, the pad conditioner further includes: a tuning base, a surface of which has a central area and an edge area surrounding the central area, a shape of the edge area corresponding to a shape of the pressure sensing ring; and tuning particles, disposed in the central area.

In some possible embodiments, the control unit is configured to: in response to the pressure data being out of a preset pressure range, set the pad conditioner in an idle state; and in response to the pressure data being within the preset pressure range, set the pad conditioner in a polishing state; where in response to the pad conditioner being in the polishing state, the pad conditioner performs at least one tuning on the polishing pad.

In addition to the technical problems solved by the embodiment of the present application, the technical features constituting the technical solution and the beneficial effects brought by the technical features of these technical solutions described above, other technical problems solved by the polishing apparatus and the polishing method provided in the embodiments of the present application, other technical features included in the technical solutions and the beneficial effects brought by these technical features will be further explained in detail in specific embodiments.

In the related art, there exists a problem that the pad conditioner has poor tuning effect of the polishing pad. The inventor found after research that the reason is that the pad conditioner will exert a certain pressure on the polishing pad when tuning the polishing pad, and this pressure data is provided by a factory's compressor dry air (CDA). Where, the CDA is used to supply a power gas source for a pneumatic apparatus in FAB (Fabrication, FAB) and is for the purpose of purge, and the pressure data reflect the pressure of compressed air on the pad conditioner, not the real pressure of the pad conditioner, and it is difficult to monitor the pressure of the pad conditioner in real time, which makes the pad conditioner has poor tuning effect on the polishing pad. If the pressure of the pad conditioner deviates, it will cause the polishing pad to be abnormal, for example, the polishing pad will be worn out, and then the profile of the wafer will be abnormal, broken or scratched, and even the wafer will be scrapped. In addition, the pad conditioner requires manual measurement and calibration of pressure, which is labor-consuming.

Therefore, an embodiment of the present application provides a polishing apparatus, which includes a polishing pad, a pad conditioner, a cleaning nozzle, a pressure detecting unit and a control unit. The pad conditioner can be moved to the pressure detecting unit and come into contact with the pressure detecting unit. The pressure detecting unit measures the pressure data of the pad conditioner. The cleaning nozzle is used for cleaning the pad conditioner, and the control unit controls the working state of the pad conditioner according to the pressure data. Use of the pressure detecting unit to monitor the pad conditioner may prevent the polishing pad from damage due to an excessively large pressure of the pad conditioner or by-products on the polishing pad from being difficult to be removed due to an excessively small pressure of the pad conditioner, and ensure the tuning effect.

In order to make the above objectives, features and advantages of the embodiments of the present application more obvious and easy to be understood, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

Referring toto, an embodiment of the present application provides a polishing apparatus, which includes a polishing pad, a pad conditioner, a cleaning nozzle, a pressure detecting unitand a control unit. The polishing pad may polish, for example, a wafer, and the pad conditioner is movable, for example, the pad conditioner may be moved onto the polishing pad to polish and tune the polishing pad. The pressure detecting unitis used to measure the pressure of the pad conditioner, and the cleaning nozzleis used to clean the pad conditioner and clean a by-product adhered to the pad conditioner. The control unit is electrically connected with the pad conditioner and the pressure detecting unit, to control the working state of the pad conditioner according to the pressure data.

In some further embodiments, the polishing pad is disposed on a polishing disk, and the polishing pad is supported and fixed by the polishing disk. The polishing surface of the polishing pad is opposite to the surface of the wafer. The polishing pad can be a round pad, and the polishing surface of the polishing pad is provided with a plurality of protrusions, which are used for rubbing against the wafer when the polishing pad is rotating, and the material of the protrusions can be polyurethane fiber, and so on.

The pad conditioner polishes the polishing surface of the polishing pad and takes away by-products (such as polishing products and polishing liquid crystals) to keep the polishing surface of the polishing pad active and ensure the stability of the polishing speed rate. The pad conditioner includes a tuning baseand tuning particlesdisposed on a surface of the tuning base, and the tuning baseand the tuning particlesform a tuning disk.

Referring to, the tuning particlescan be diamond particles, which are disposed on a surface (e.g., lower surface) of the tuning basefacing the polishing pad, that is, the diamond particles are disposed at one end of the tuning baseclose to the polishing pad, and the tuning disk rubs against the polishing pad by the rotation and reciprocating motion of the pad conditioner, thus tuning the polishing surface of the polishing pad.

The surface of the tuning basehas a central areaand an edge areasurrounding the central area. The edge areais the edge of the tuning baseas shown by the black ring in. The surface of the tuning baserefers to the surface of the tuning basefacing the polishing pad. The central areais provided with tuning particles, which are shown as the black dots in, while the edge areais not provided with the tuning particles. When detecting the pressure data of the pad conditioner, the edge areais in contact with the pressure detecting unit.

In some possible embodiments, referring toand, the pad conditioner further includes a baseand an adjusting arm, where the baseis disposed at a side of the polishing disk, and one end of the adjusting armis rotatably connected to the base, and the other end thereof is connected to the tuning base. The adjusting armcan swing back and forth around the basewithin a preset angle range, so as to drive the pad conditioner to swing back and forth within a preset angle range. A driving unit can be disposed in the base, and the driving unit is electrically connected with the adjusting armand the control unit to control the pressure of the adjusting armand the rotating speed of the tuning base.

The pad conditioner has a variety of working states. For example, the working states of the pad conditioner include a polishing state and an idle state. When the pad conditioner is in the polishing state, the pad conditioner performs at least one tuning on the polishing pad. When the pad conditioner is in the idle state, it is stationary to achieve shutdown, and does not tune the polishing pad. At this time, the pad conditioner may still be in contact with the polishing pad, or the pad conditioner may be away from the polishing pad for a certain distance.

The working states of the pad conditioner may also include a cleaning state. When the pad conditioner is in the cleaning state, the pad conditioner is cleaned to clean off the polishing product and polishing liquid crystal adhered to the pad conditioner.

With continued reference to, the pressure detecting unitmeasures the pressure data of the pad conditioner to prevent the pressure of the pad conditioner from being too large or too small. When the pressure of the pad conditioner is too large, the pad conditioner may damage the polishing pad or even wear it out when tuning the polishing pad. When the pressure of the pad conditioner is too small, it is difficult to remove the by-products on the polishing pad when the pad conditioner polishes and tunes the polishing pad, and the tuning effect is poor.

In some possible embodiments, referring toand, the pressure detecting unitincludes a hollow baseand a pressure sensing elementdisposed on the hollow base. The hollow baseis provided on the cleaning nozzle, and the cleaning nozzlecan clean the pad conditioner through the hollow base. The pressure sensing elementis disposed on the hollow base, and the pressure sensing elementis used for sensing pressure data. When the pressure detecting unitmeasures the pressure data of the pad conditioner, the pressure sensing elementabuts against the edge areaof the tuning base.

As shown inand, the hollow baseis provided with a pressure sensing elementat one end away from the cleaning nozzleso that the hollow basesupports the pressure sensing element, and the hollow baseand the pressure sensing elementcan be detachably connected, such as clamping, bonding and the like. The pressure sensing elementfaces the pad conditioner, and is closer to the pad conditioner, and thus is convenient to perform pressure measurement on the pad conditioner.

When the pressure detecting unitmeasures the pressure data of the pad conditioner, the pressure sensing elementabuts against the edge of the tuning base, i.e., contacting with the edge areaof the tuning base. In this way, the pressure sensing elementis not in contact with the tuning particles, avoiding the tuning particlesbeing damaged or falling due to friction.

In some possible embodiments, the pressure sensing elementincludes a pressure sensing ring, which has the same shape as an end of the hollow baseaway from the cleaning nozzle. When the pressure detecting unitmeasures the pressure data of the pad conditioner, the pressure sensing ringabuts against the edge areaof the tuning base, and the tuning particlesare located in an area surrounded by the pressure sensing ring.

As shown inand, the pressure sensing ringis in a shape of ring, for example, annular or elliptical, and may be the same shape as the shape of the edge areaof the tuning base, so as to abut against the edge areaof the tuning baseto measure the pressure data of the pad conditioner. Where, the edge areacan be larger than the pressure sensing ring, so as to prevent the central areafrom contacting with the pressure sensing ringduring operation, which would otherwise affect the cleaning effect.

The pressure sensing ringis enclosed to form a first accommodating spaceto accommodate the tuning particlesand to ensure a certain space between the tuning particlesand the hollow base. With this arrangement, the contact between the pressure sensing ringand the tuning particlescan be avoided, and also the contact between the hollow baseand the tuning particlescan be avoided, thus reducing damage to the tuning particles.

The pressure sensing ringconverts a pressure signal into an electrical signal for transmission. In some possible embodiments, the pressure sensing ringincludes a conductive material layer, a spacer layer and a pressure-sensitive material layer, which are disposed in a stacked manner. A material of the spacer layer include a polyester material, so as to make the pressure sensing ringflexible and avoid damage to the tuning base. The spacer layer has a gap. When the pressure sensing ringis pressed, the conductive material layer and the pressure-sensitive material layer are bonded to establish electrical conduction, causing change in resistance of the pressure sensing ring. According to the change in resistance of the pressure sensing ring, the pressure data of the polishing pad can be obtained.

In order to further avoid the contact between the hollow baseand the tuning particles, in some possible embodiments, referring to, the pressure sensing elementfurther includes a plurality of supporting legs, which are disposed at intervals and are all disposed between the pressure sensing ringand the hollow base. By arranging a plurality of supporting legsbetween the pressure sensing ringand the hollow base, the distance between the pressure sensing ringand the hollow baseis increased, and thus the distance between the tuning particlesand the hollow baseis increased, thereby avoiding the contact between the hollow baseand the tuning particles.