US20230390882A1

US20230390882A1 - System, control method and apparatus for chemical mechanical polishing

Info

Publication number: US20230390882A1
Application number: US17/832,696
Authority: US
Inventors: Te-Chien Hou; Wen-Pin Liao; Chen-Chi Tang; Shich-Chang Suen; Kei-Wei Chen
Original assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
Current assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
Priority date: 2022-06-06
Filing date: 2022-06-06
Publication date: 2023-12-07

Abstract

Disclosed are a chemical mechanical polishing apparatus, a control method for the chemical mechanical polishing apparatus and a chemical mechanical polishing system. In one embodiment, the chemical mechanical polishing apparatus includes a polishing pad, a sensor, a polishing head and a conditioner. The sensor is configured to obtain surface roughness of the polishing pad. The polishing head is located above the polishing pad and configured to polish a wafer which is push against the polishing pad. The conditioner is located on the polishing pad and configured to recondition the polishing pad, wherein the conditioner is operated according to at least one polishing condition, and the polishing condition is tuned according to the surface roughness of the polishing pad.

Description

BACKGROUND

During semiconductor fabrication process, a substrate (e.g., semiconductor wafer) may be polished or planarized one or more times to remove a portion on a top surface of the wafer. A typical polishing process is a chemical mechanical polishing (CMP), where the wafer is polished by being placed on polishing head and pressed facedown onto the polishing pad. During the polishing process, the characteristic of the polishing pad may be changed (e.g., polishing pad may be worn out), thereby reducing the polishing rate and the quality of the polished wafer. Thus, pad conditioning is performed by a conditioner to recondition the surface of the polishing pad. However, the existing approaches do not provide an effective way to monitor conditions or profile of the polishing pad and make appropriate adjustments for the CMP apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 and FIG. 2 schematically illustrate a top view and a side view of a chemical-mechanical polishing (CMP) system in accordance with some embodiments of the present disclosure.

FIG. 3 schematically illustrates a block diagram of a closed loop control system for CMP process stability in accordance with some embodiments of the present disclosure.

FIG. 4A through FIG. 9 schematically illustrate various flowcharts of control methods for chemical mechanical polishing apparatus in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one component or feature's relationship to another component(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
Chemical-mechanical polishing (CMP) is one of the commonly used polishing solutions. Ideally, a wafer should be polished homogeneously and uniformly across the entire wafer. The removal rate should be identical on every measurement spot within a wafer. Unfortunately, in reality, the removal rate has regional variation, which results in a thickness variation within wafer (WiW), wafer to wafer (WtW) or lot to lot (LtL). The removal rate of the CMP process has a high correlation with surface roughness (e.g., Ra, Rpk, or Rvk) of a polishing pad. “Ra” stands for average, or arithmetic average of profile height deviations from the mean line. “Rpk” stands for average of peak height above the mean line. “Rvk” stands for average of valley depth below the mean line. If the surface roughness of the polishing pad is analyzed after the end of pad life time, the surface roughness of the polishing pad cannot be obtained in time when the removal rate and WiW/WtW/LtL thickness vary or continuously increase or decrease during polishing. In addition, un-optimized conditioning recipe can also lead to increasing or decreasing removal rate at some positions/regions of the polishing pad over the period of pad life, which may increase the out of control rate and rework rate of the volume production. In order to acquire a good conditioning recipe, lots of wafers (over 600 pcs) would be used for tuning (so-called marathon experiment), which could also take a large amount of time (normally one week) and resources (wafer/slurry/chemical).
The present disclosure is related to a chemical mechanical polishing apparatus, a control method for the chemical mechanical polishing apparatus and a chemical mechanical polishing system to form a planar top surface of the wafer (or other object). In some embodiments, a pad conditioning process is performed prior to or synchronously with the chemical mechanical polishing process to control surface roughness (e.g., at least one of Ra, Rpk and Rvk) of the polishing pad so that removal rate within the polishing pad is uniform, which helps improve WiW, WtW or LtL uniformity of the chemical mechanical polishing process.
FIG. 1 and FIG. 2 schematically illustrate a top view and a side view of a chemical-mechanical polishing system in accordance with some embodiments of the present disclosure. FIG. 3 schematically illustrates a block diagram of a closed loop control system for CMP process stability in accordance with some embodiments of the present disclosure. FIG. 4 through FIG. 9 schematically illustrate various flowcharts of control methods for chemical mechanical polishing apparatus in accordance with some embodiments of the present disclosure.
Referring to FIG. 1 and FIG. 2 , a chemical-mechanical polishing system 1 in accordance with some embodiments of the present disclosure is provided. The chemical-mechanical polishing system 1 includes a chemical mechanical polishing apparatus 10 and a controller CT, but the present disclosure is not limited thereto. The chemical-mechanical polishing system 1 may further include other elements or devices according to different requirements. For example, although not shown in the figures, the chemical-mechanical polishing system 1 may further include a memory connected to the controller CT, or other elements or devices.
The chemical mechanical polishing apparatus 10 in accordance with some embodiments of the present disclosure includes a polishing pad P, a sensor MS, a polishing head H and a conditioner CD, but the present disclosure is not limited thereto. The chemical mechanical polishing apparatus 10 may further include other elements according to different requirements. For example, the chemical mechanical polishing apparatus 10 may further include a platen PL, a robotic arm R and a slurry dispenser SD, but the present disclosure is not limited thereto.
The polishing pad P is disposed on or attached to the platen PL. When the platen PL rotates, the polishing pad P rotates accordingly. The polishing pad P may include a plurality of grooves (not shown) formed randomly or in any specific pattern as long as the grooves are able to provide the desired functions. For example, the patterns of the grooves may include concentric circular pattern, radial pattern, Cartesian grid pattern, spiral pattern, rotated Cartesian grid pattern, and any combination thereof.
The sensor MS is configured to obtain surface roughness of the polishing pad P. In some embodiments, the sensor MS is located above the polishing pad P, and the sensor MS obtains the surface roughness of the polishing pad P in a non-contact manner. In this way, damage to the polishing pad P caused by surface roughness measurement can be reduced. In some embodiments, the sensor MS is configured to capture images of the polishing pad P to obtain surface roughness of the polishing pad P. In some embodiments, the sensor MS includes confocal microscopy, a three-dimensional image sensor or other devices that are capable of obtaining three-dimensional images of the polishing pad P. The three-dimensional images of the polishing pad P can be used to confirm surface morphology of the polishing pad P, and the surface roughness information of the polishing pad P can be calculated or obtained from the surface morphology of the polishing pad P.
A field of view (FOV, i.e., the maximum region of the polishing pad P that the sensor MS can image) of the sensor MS may be larger than, equal to or smaller than an area of the polishing pad P. When the field of view of the sensor MS is smaller than the area of the polishing pad P, the sensor MS is unable to capture the image of the entire polishing pad P at one time (or with one shot). In the embodiments in which the field of view of the sensor MS is smaller than the area of the polishing pad P, the robot arm R is configured to move the sensor MS so that the sensor MS can capture images that cover the entire polishing pad P. For example, the robotic arm R is configured to move the sensor MS between a center and an edge of the polishing pad P (as indicated by the double arrow inside the outline of the polishing pad P in FIG. 1 ) so that the sensor MS is able to capture images correspond to regions between the center and the edge of the polishing pad P, and thus the surface roughness of the entire polishing pad P (from the center to the edge) can be obtained or calculated from the three-dimensional images obtained by the sensor MS.
In some embodiments, the sensor MS is fixed to an end portion of the robotic arm R or hold by the end portion of the robotic arm R, so that when the end portion of the robotic arm R moves between the center and the edge of the polishing pad P, the sensor MS moves with the robot arm R between the center and the edge of the polishing pad P. It should be noted that the relative position or connection manner of the robotic arm R and the sensor MS shown in FIG. 1 and FIG. 2 is for illustration purposes and the present disclosure is not limited thereto.
The polishing head H is located above the polishing pad P and configured to polish a wafer W which is push against the polishing pad P. Specifically, the polishing head H may provide a controllable load to the wafer W to push the wafer W against the polishing pad P. During polishing process, the polishing head H may rotate with a specific or adjustable downward force to polish the wafer W.
In some embodiments, the polishing head H includes a carrier head CH, a membrane MB and a retaining ring RR, but the present disclosure is not limited thereto. The membrane MB is located between the carrier head CH and the wafer W. A space (or a cavity or a chamber) between the carrier head CH and the membrane MB can be sealed. Sealing the cavity between the membrane MB and the carrier head CH allows the cavity to be positively or negatively pressurized as required.
The membrane MB may be flexible and includes an inner surface that forms the boundary of a pressurizable chamber (not labeled) and an outer surface that forms a mounting surface to receive a backside of the wafer W and to press a frontside of the wafer W against the polishing pad P. During polishing, the chamber is pressurized to cause the membrane MB to expand outwardly and apply the load to the wafer W, which presses the wafer W against the polishing pad P. After polishing, the wafer W is chucked to the outer surface, lifted off the polishing pad P, and moved to another location, such as a transfer station or another polishing pad.
The retaining ring RR surrounds the membrane MB, and the wafer W can be held by the retaining ring RR. Specifically, the retaining ring RR may have an inner surface and a lower surface, wherein the inner surface of the retaining ring RR can be configured to circumferentially surround the edge of the wafer W to retain the wafer W during polishing, and the lower surface of the retaining ring RR can be brought into contact with the polishing pad P.
The slurry dispenser SD is configured to supply polishing slurry S to the surface of the polishing pad P during polishing process. The polishing slurry S may include at least one chemically reactive agent and abrasive particles, but the present disclosure is not limited thereto. In some embodiments, the slurry dispenser SD may be further configured to control a flow rate of the polishing slurry S. In some embodiments, the flow rate of the polishing slurry S may be tuned during the polishing process according to the surface roughness of the polishing pad P.
The conditioner CD is located on the polishing pad P and configured to recondition the polishing pad P so as to recover the characteristics (e.g., surface roughness) of the polishing pad P. In some embodiments, the conditioner CD may be made from metal which is embedded with diamond particles, but the present disclosure is not limited thereto. In some embodiments, the conditioner CD is operated according to at least one polishing condition, and the polishing condition is tuned according to the surface roughness of the polishing pad P. In some embodiments, the at least one polishing condition includes at least one of a rotational speed of the conditioner CD, a downward force of the conditioner CD that pushes the wafer W against the polishing pad P and a polishing time of the conditioner CD, but the present disclosure is not limited thereto. For example, the at least one polishing condition may include at least one of a sweep range and a sweep frequency of the conditioner CD, but the present disclosure is also not limited thereto.
The conditioner CD generally rotates and moves between the center and the edge of the polishing pad P as indicated by the double arrow inside the outline of the polishing pad P in FIG. 1 . In some embodiments, the robotic arm R is further configured to move the conditioner CD between the center and the edge of the polishing pad P so that the conditioner CD is able to polish the polishing pad P from the center to the edge of the polishing pad P. For example, the conditioner CD may be fixed to the robotic arm R at a position near the sensor MS so that the conditioner CD may be moved synchronously with the sensor MS, and that the sensor MS is able to capture images of the polishing pad P near the conditioner CD, and thus the surface roughness of the polishing pad P near the conditioner CD can be obtained. In other embodiments, although not shown, the conditioner CD and the sensor MS may be fixed to different robotic arms, and the conditioner CD may be moved synchronously or asynchronously with the sensor MS.
In some embodiments, the conditioner CD and the sensor MS may be moved in parallel on the polishing pad P, and the sensor MS can capture images of the polishing pad P that is reconditioned by the conditioner CD, but the present disclosure is also not limited thereto. In other embodiments, although not shown, the sensor MS may be positioned upstream of the conditioner CD, and the sensor MS can capture images of the polishing pad P that is to be reconditioned by the conditioner CD; or the sensor MS may be positioned downstream of the conditioner CD, and the sensor MS can capture images of the polishing pad P already reconditioned by the conditioner CD; or two sensors MS may be provided upstream and downstream of the conditioner CD to capture images of the polishing pad P to be reconditioned and already reconditioned by the conditioner CD.
Once the surface roughness of the polishing pad P is obtained by the sensor MS, the at least one polishing condition (parameters) of the conditioner CD may be tuned according to the obtained/calculated surface roughness. In some embodiments, at least one of the rotational speed of the conditioner CD, the downward force of the conditioner CD, the polishing time of the conditioner CD, the sweep range of the conditioner CD and the sweep frequency of the conditioner CD are tuned according to the surface roughness of the polishing pad P. However, the present disclosure is not limited thereto and any other polishing conditions (or parameters) of the conditioner CD may be tuned according to the surface roughness of the polishing pad P.
The controller CT is coupled to the chemical mechanical polishing apparatus 10, and is configured to tune at least one polishing condition according to the surface roughness of the polishing pad P and control the conditioner CD according to the at least one polishing condition. For example, the controller CT is coupled to the sensor MS to receive data or obtained results from the sensor MS, and the controller CT is coupled to the conditioner CD to control the conditioner CD according to the at least one polishing condition.
Referring to FIG. 3 , a closed loop control system for a pad conditioning process in accordance with some embodiments of the present disclosure is provided. The closed loop control system for a pad conditioning process may include a filter F, the controller CT, the conditioner CD and the sensor MS, but the present disclosure is also not limited thereto.
A pad conditioning process may be activated when a start signal is input to the filter F. The filter F is configured to filter noises in the start signal or any other signal to be input to the controller CT. In some embodiments, the filter F can be hardware or software (e.g., programmable code or algorithm) stored in the controller CT. In other embodiments, the filter F may be hardware provided in a device (not shown) other than the controller CT or software stored in the cloud.
The controller CT receives the signal filtered by the filter F. The controller CT may be a micro-IC, a computing device or any other device that is capable of receiving, processing and transmitting signal(s), performing calculation and/or determination step(s) and controlling the conditioner CD or any other device based on the signal(s). In some embodiments, the surface roughness of the polishing pad P is calculated by the controller CT based on the signals produced from the sensor MS and filtered by the filter F; alternatively, the surface roughness of the polishing pad P may be calculated by the processor stored in the sensor MS or in other device or by the software stored in the cloud. The controller CT determines whether at least one of the polishing conditions (e.g., the rotational speed of the conditioner CD, the downward force of the conditioner CD, the polishing time of the conditioner CD, the sweep range of the conditioner CD and the sweep frequency of the conditioner CD) should be tuned according to the obtained surface roughness and instruct the conditioner CD to operate accordingly.
Take FIG. 2 as an example, the wafer W is positioned between the center and the edge of the polishing pad P, wherein the peripheral region of the wafer W corresponds to the center and edge regions of the polishing pad P, and the central region of the wafer W corresponds to an intermediate region of the polishing pad P between the center and the edge of the polishing pad P. If the surface roughness of the center and edge regions of the polishing pad P is lower than the surface roughness of the intermediate region of the polishing pad P, the removal rate in the central region of the wafer W will be greater than the removal rate in the peripheral region of the wafer W. Namely, the central region of the wafer W will be removed faster than the peripheral region of the wafer W. When the controller CT confirms the existence of surface roughness variation of the polishing pad P and the surface roughness variation is higher than an acceptable value, the controller CT determines that at least one of the polishing conditions should be adjusted and instructs the conditioner CD to act accordingly.
Since the above listed polishing conditions (parameters) of the conditioner CD is correlated with the removal rate, the surface roughness variation of the polishing pad P can be reduced by tuning at least one of the polishing conditions, thereby making the removal rate of the entire surface of the wafer W more uniform. For example, the rotational speed, the downward force and the polishing time of the conditioner CD are positively correlated with the removal rate, namely, the higher the rotational speed/the downward force/the polishing time, the higher the removal rate. Therefore, at least one of the rotational speed, the downward force and the polishing time of the conditioner CD may be increased when the conditioner CD reaches the center or the edge region of the polishing pad P, and at least one of the rotational speed, the downward force and the polishing time of the conditioner CD may be decreased or remain the same when the conditioner CD reaches the intermediate region of the polishing pad P, so that the reconditioned polishing pad P has a more uniform overall surface roughness.
Referring back to FIG. 3 , the sensor MS may capture images of the reconditioned or to-be-reconditioned polishing pad P and produce corresponding signals to the filter F. For example, the sensor MS includes confocal microscopy or a three-dimensional image sensor, but the present disclosure is not limited thereto. In some embodiments, a field of view of the sensor MS is smaller than an area of the polishing pad P, and capturing the images of the polishing pad P includes moving the sensor MS between a center and an edge of the polishing pad P so that the sensor MS is able to capture images correspond to regions between the center and the edge of the polishing pad P. The signals from the sensor MS are filtered by the filter F and then transmitted to the controller CT. The controller CT determines whether at least one of the polishing conditions should be tuned according to the obtained surface roughness and instruct the conditioner CD to operate accordingly.
By continuously and timely tuning at least one of the polishing conditions of the conditioner CD, the uniformity of the surface roughness of the polishing pad P can be improved, thereby improving WiW, WtW or LtL uniformity of the chemical mechanical polishing process. Since the surface roughness variation can be reduced and stability of the polished thickness can be controlled, higher yield can be achieved and wafer acceptance test (WAT) performance can be boosted. In addition, the pad life time may be extended, the time, cost and resources for acquiring a good conditioning recipe may be reduced.
Referring to FIG. 4A and FIG. 4B, a control method for a chemical mechanical polishing apparatus (e.g., the chemical mechanical polishing apparatus in FIG. 1 and FIG. 2 ) in accordance with some embodiments of the present disclosure is provided. The control method may include a pad conditioning process (step S1), a CMP process (step S2) and a cleaning process (step S3) performed in sequence, but the present disclosure is not limited thereto.
In some embodiments, the pad conditioning process (step S1) may include the following steps: capturing, by the sensor, images of the polishing pad to obtain surface roughness of the polishing pad (step S10); tuning at least one polishing condition according to the surface roughness of the polishing pad (step S11); and reconditioning, by the conditioner, the polishing pad according to the at least one polishing condition (step S12), as shown in FIG. 4B, but the present disclosure is not limited thereto.
In step S10, the sensor may include confocal microscopy, a three-dimensional image sensor or other devices that are capable of obtaining three-dimensional images of the polishing pad. When the field of view of the sensor MS is smaller than the area of the polishing pad P, capturing the images of the polishing pad includes moving the sensor between the center and the edge of the polishing pad so that the sensor is able to capture images correspond to regions between the center and the edge of the polishing pad, thereby the surface roughness of various regions of the polishing pad can be obtained.
In step S11, the at least one polishing condition of the conditioner may be tuned by the controller according to the surface roughness of the polishing pad, and the controller instructs the conditioner to operate according to the at least one of the polishing conditions. For example, when the existence of surface roughness variation of the polishing pad is confirmed by the controller and the surface roughness variation is determined to be higher than an acceptable value by the controller, the controller determines that at least one of the polishing conditions should be adjusted and instructs the conditioner to act accordingly. For example, at least one of the rotational speed of the conditioner CD, the downward force of the conditioner CD, the polishing time of the conditioner CD, the sweep range of the conditioner CD and the sweep frequency of the conditioner CD may be tuned according to the obtained surface roughness.
In step S12, reconditioning the polishing pad includes moving the conditioner between the center and the edge of the polishing pad so that the conditioner is able to polish the polishing pad from the center to the edge of the polishing pad. In some embodiments, the sensor and the conditioner are moved synchronously, but the present disclosure is not limited thereto.
In some embodiments, the step of reconditioning the polishing pad is performed prior to the step of polishing the wafer (step S2). In some embodiments, the CMP process (step S2) may include polishing a wafer which is push against the polishing pad by the polishing head. As described above, the polishing head may rotate with a specific or adjustable downward force to polish the wafer during the polishing process. For other related descriptions, please refer to the above, and will not be repeated here.
In some embodiments, the cleaning process (step S3) may include a post-CMP cleaning process to remove the residual slurry particles, organic residues, foreign materials, metallic impurities, etc., from the wafer surfaces. Various kinds of cleaning solutions, such as SC-1, SC-2, SPM and/or DHF, may be adopted to meet the requirements for the level of acceptable defects.
Referring to FIG. 5 , a control method for a chemical mechanical polishing apparatus (e.g., the chemical mechanical polishing apparatus in FIG. 1 and FIG. 2 ) in accordance with some embodiments of the present disclosure is provided. The main difference between the control method in FIG. 5 and the control method in FIG. 4A is that the control method in FIG. 5 further includes another pad reconditioning process (step S1) performed after the step S3. In other words, the step of reconditioning the polishing pad (step S1) is performed again after the step of polishing the wafer (step S2), or, as shown in FIG. 5 , after the cleaning process (step S3). For details of the two steps S1, step S2 and step S3, please refer to the related description of FIG. 4B, which will not be repeated here.
By performing the step of reconditioning the polishing pad (step S1) after the cleaning process (step S3), the polishing pad can have a uniform surface roughness before the next CMP process.
Referring to FIG. 6 , a control method for a chemical mechanical polishing apparatus (e.g., the chemical mechanical polishing apparatus in FIG. 1 and FIG. 2 ) in accordance with some embodiments of the present disclosure is provided. The control method in FIG. 6 may include a pad conditioning process and a CMP process performed synchronously (step S1′) and a cleaning process (step S3), wherein step S1′ and step S3 are performed in sequence, hut the present disclosure is not limited thereto.
In step S1′, the step of reconditioning the polishing pad is performed synchronously with the step of polishing the wafer. Namely, during the wafer polishing process, the pad conditioning process described in FIG. 3 and FIG. 4B is performed at the same time. During the wafer polishing process, by continuously and timely obtaining the surface roughness information and adjusting at least one polishing condition of the conditioner accordingly, the steps required for the control method can be simplified and the uniformity of the removal rate can be effectively controlled, thereby helping to improve the WiW thickness uniformity.
Referring to FIG. 7 , a control method for a chemical mechanical polishing apparatus (e.g., the chemical mechanical polishing apparatus in FIG. 1 and FIG. 2 ) in accordance with some embodiments of the present disclosure is provided. The main difference between the control method in FIG. 7 and the control method in FIG. 6 is that the control method in FIG. 7 further includes a pad reconditioning process (step S1) performed after the step S3. In other words, the step of reconditioning the polishing pad (step S1) is performed again after the step of polishing the wafer (e.g., step S1′), or, as shown in FIG. 7 , after the cleaning process (step S3). For details of the step S1′, step S3 and step S1, please refer to the related description above, which will not be repeated here.
Referring to FIG. 8 , a control method for a chemical mechanical polishing apparatus (e.g., the chemical mechanical polishing apparatus in FIG. 1 and FIG. 2 ) in accordance with some embodiments of the present disclosure is provided. The main difference between the control method in FIG. 8 and the control method in FIG. 7 is that the step of reconditioning the polishing pad (step S1) is performed prior to the step of polishing the wafer (e.g., step S1′), and the step of reconditioning the polishing pad is performed again synchronously with the step of polishing the wafer (e.g., step S1′).
By performing the step of reconditioning the polishing pad (step S1) before the step of polishing the wafer (e.g., step S1′), the polishing pad can have a uniform surface roughness before the CMP process.
Referring to FIG. 9 , a control method for a chemical mechanical polishing apparatus (e.g., the chemical mechanical polishing apparatus in FIG. 1 and FIG. 2 ) in accordance with some embodiments of the present disclosure is provided. The main difference between the control method in FIG. 9 and the control method in FIG. 8 is that the control method in FIG. 9 further includes a pad reconditioning process (step S1) performed after the step S3. In other words, the step of reconditioning the polishing pad (step S1) is performed for the third time after the step of polishing the wafer (e.g., step S1′), or, as shown in FIG. 9 , after the cleaning process (step S3). For details of the step S1′, step S3 and the two steps S1, please refer to the related description above, which will not be repeated here.
Based on the above discussions, it can be seen that the present disclosure offers various advantages. It is understood, however, that not all advantages are necessarily discussed herein, and other embodiments may offer different advantages, and that no particular advantage is required for all embodiments.
In accordance with some embodiments of the present disclosure, a chemical mechanical polishing apparatus includes a polishing pad, a sensor, a polishing head and a conditioner. The sensor is configured to obtain surface roughness of the polishing pad. The polishing head is located above the polishing pad and configured to polish a wafer which is push against the polishing pad. The conditioner is located on the polishing pad and configured to recondition the polishing pad, wherein the conditioner is operated according to at least one polishing condition, and the polishing condition is tuned according to the surface roughness of the polishing pad. In some embodiments, the sensor is configured to capture images of the polishing pad to obtain surface roughness of the polishing pad. In some embodiments, the sensor includes confocal microscopy or a three-dimensional image sensor. In some embodiments, a field of view of the sensor is smaller than an area of the polishing pad, and the chemical mechanical polishing apparatus further includes a robotic arm configured to move the sensor between a center and an edge of the polishing pad so that the sensor is able to capture images correspond to regions between the center and the edge of the polishing pad. In some embodiments, the robotic arm is further configured to move the conditioner between the center and the edge of the polishing pad so that the conditioner is able to polish the polishing pad from the center to the edge of the polishing pad. In some embodiments, the at least one polishing condition includes at least one of a rotational speed of the conditioner, a downward force of the conditioner that pushes the wafer against the polishing pad and a polishing time of the conditioner.
In accordance with some embodiments of the present disclosure, a control method for a chemical mechanical polishing apparatus having a polishing pad, a sensor, a polishing head and a conditioner includes the following steps: capturing, by the sensor, images of the polishing pad to obtain surface roughness of the polishing pad; tuning at least one polishing condition according to the surface roughness of the polishing pad; polishing a wafer which is push against the polishing pad by the polishing head; and reconditioning, by the conditioner, the polishing pad according to the at least one polishing condition. In some embodiments, the sensor includes confocal microscopy or a three-dimensional image sensor. In some embodiments, a field of view of the sensor is smaller than an area of the polishing pad, and capturing the images of the polishing pad includes moving the sensor between a center and an edge of the polishing pad so that the sensor is able to capture images correspond to regions between the center and the edge of the polishing pad. In some embodiments, reconditioning the polishing pad includes moving the conditioner between the center and the edge of the polishing pad so that the conditioner is able to polish the polishing pad from the center to the edge of the polishing pad. In some embodiments, the sensor and the conditioner are moved synchronously. In some embodiments, the at least one polishing condition includes at least one of a rotational speed of the conditioner, a downward force of the conditioner that pushes the wafer against the polishing pad and a polishing time of the conditioner. In some embodiments, the step of reconditioning the polishing pad is performed prior to the step of polishing the wafer. In some embodiments, the step of reconditioning the polishing pad is performed again after the step of polishing the wafer. In some embodiments, the step of reconditioning the polishing pad is performed again synchronously with the step of polishing the wafer. In some embodiments, the step of reconditioning the polishing pad is performed for the third time after the step of polishing the wafer. In some embodiments, the step of reconditioning the polishing pad is performed synchronously with the step of polishing the wafer. In some embodiments, the step of reconditioning the polishing pad is performed again after the step of polishing the wafer.
In accordance with alternative embodiments of the present disclosure, a chemical mechanical polishing system includes a chemical mechanical polishing apparatus and a controller. The chemical mechanical polishing apparatus includes a polishing pad, a sensor, a polishing head and a conditioner. The sensor is configured to obtain surface roughness of the polishing pad. The polishing head is located above the polishing pad and configured to polish a wafer which is push against the polishing pad. The conditioner is located on the polishing pad and configured to recondition the polishing pad. The controller is coupled to the chemical mechanical polishing apparatus, and is configured to tune at least one polishing condition according to the surface roughness of the polishing pad and control the conditioner according to the at least one polishing condition. In some embodiments, the sensor is configured to capture images of the polishing pad to obtain surface roughness of the polishing pad. In some embodiments, the sensor includes confocal microscopy or a three-dimensional image sensor.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

1. A chemical mechanical polishing apparatus, comprising:

a polishing pad;

a sensor configured to obtain surface roughness of the polishing pad;

a polishing head located above the polishing pad and configured to polish a wafer which is push against the polishing pad; and

a conditioner located on the polishing pad and configured to recondition the polishing pad, wherein the conditioner is operated according to at least one polishing condition, and the polishing condition is tuned according to the surface roughness of the polishing pad.

2. The chemical mechanical polishing apparatus according to claim 1, wherein the sensor is configured to capture images of the polishing pad to obtain surface roughness of the polishing pad.

3. The chemical mechanical polishing apparatus according to claim 2, wherein the sensor comprises confocal microscopy or a three-dimensional image sensor.

4. The chemical mechanical polishing apparatus according to claim 1, wherein a field of view of the sensor is smaller than an area of the polishing pad, and

wherein the chemical mechanical polishing apparatus further comprises:

a robotic arm configured to move the sensor between a center and an edge of the polishing pad so that the sensor is able to capture images correspond to regions between the center and the edge of the polishing pad.

5. The chemical mechanical polishing apparatus according to claim 4, wherein the robotic arm is further configured to move the conditioner between the center and the edge of the polishing pad so that the conditioner is able to polish the polishing pad from the center to the edge of the polishing pad.

6. The chemical mechanical polishing apparatus according to claim 1, wherein the at least one polishing condition comprises at least one of a rotational speed of the conditioner, a downward force of the conditioner that pushes the wafer against the polishing pad and a polishing time of the conditioner.

7. A control method for chemical mechanical polishing apparatus having a polishing pad, a sensor, a polishing head and a conditioner, the control method comprising:

capturing, by the sensor, images of the polishing pad to obtain surface roughness of the polishing pad;

tuning at least one polishing condition according to the surface roughness of the polishing pad;

polishing a wafer which is push against the polishing pad by the polishing head; and

reconditioning, by the conditioner, the polishing pad according to the at least one polishing condition.

8. The control method according to claim 7, wherein the sensor comprises confocal microscopy or a three-dimensional image sensor.

9. The control method according to claim 7, wherein a field of view of the sensor is smaller than an area of the polishing pad, and wherein capturing the images of the polishing pad comprises:

moving the sensor between a center and an edge of the polishing pad so that the sensor is able to capture images correspond to regions between the center and the edge of the polishing pad.

10. The control method according to claim 9, wherein reconditioning the polishing pad comprises:

moving the conditioner between the center and the edge of the polishing pad so that the conditioner is able to polish the polishing pad from the center to the edge of the polishing pad.

11. The control method according to claim 10, wherein the sensor and the conditioner are moved synchronously.

12. The control method according to claim 7, wherein the at least one polishing condition comprises at least one of a rotational speed of the conditioner, a downward force of the conditioner that pushes the wafer against the polishing pad and a polishing time of the conditioner.

13. The control method according to claim 7, wherein the step of reconditioning the polishing pad is performed prior to the step of polishing the wafer.

14. The control method according to claim 13, wherein the step of reconditioning the polishing pad is performed again after the step of polishing the wafer.

15. The control method according to claim 14, wherein the step of reconditioning the polishing pad is performed again synchronously with the step of polishing the wafer.

16. The control method according to claim 15, wherein the step of reconditioning the polishing pad is performed for the third time after the step of polishing the wafer.

17. The control method according to claim 7, wherein the step of reconditioning the polishing pad is performed synchronously with the step of polishing the wafer.

18. The control method according to claim 17, wherein the step of reconditioning the polishing pad is performed again after the step of polishing the wafer.

19. A chemical mechanical polishing system, comprising:

a chemical mechanical polishing apparatus, comprising:

a polishing pad;

a sensor configured to obtain surface roughness of the polishing pad;

a conditioner located on the polishing pad and configured to recondition the polishing pad; and

a controller coupled to the chemical mechanical polishing apparatus, and is configured to tune at least one polishing condition according to the surface roughness of the polishing pad and control the conditioner according to the at least one polishing condition.

20. The chemical mechanical polishing system according to claim 19, wherein the sensor comprises confocal microscopy or a three-dimensional image sensor.