Method and apparatus for monitoring edge bevel removal area in semiconductor apparatus and electroplating system

A semiconductor apparatus includes a transfer chamber, an annealing station, a robot arm, and an edge detector. The transfer chamber is configured to interface with an electroplating apparatus. The annealing station is arranged to anneal a wafer. The robot arm is arranged to transfer the wafer from the transfer chamber to the annealing station. The edge detector is disposed over the robot arm for the purpose of monitoring at least one portion of an edge bevel removal area of the wafer carried by the robot arm.

BACKGROUND

During the fabrication process of a wafer, forming metal lines of the integrate circuits on the wafer is an important step in the process. The metal lines may be formed by an electroplating process or a physical vapor deposition (PVD) process. To increase the integration density of a wafer, the useable area of the wafer is expanded to reach the very near edge of the wafer. As a result, metal lines are also formed on the very near edge of the wafer. However, unwanted residual metal on the wafer edge should be removed by a so-called Edge Bevel Removal (EBR) process. Since the edge bevel area is adjacent to the useable area, the EBR process is controlled to ensure that an etchant etches the edge bevel area without harming the useable area. After the EBR process, wafers are monitored to determine if any abnormal wafer edge occurs. Thus, the quality of fabricated wafers is affected by the precision of the monitoring process. Moreover, the monitoring process may also affect the speed of the fabrication process. It may thus be desirable to provide a reliable and accurate monitoring method to increase the yield rate of semiconductor wafers.

DETAILED DESCRIPTION

FIG. 1is a diagram illustrating an electroplating system100in accordance with some embodiments. Referring toFIG. 1, the electroplating system100comprises a dosing apparatus12, an electroplating apparatus14, and a semiconductor apparatus16. The dosing apparatus102comprises a dosing device122, a central bath device124, a filtration and pumping device126, and a controlling device128. The dosing device122is arranged to store and deliver chemical additives for the plating solution. The central bath device124is arranged to hold the chemical solution used as the electroplating bath in the electroplating apparatus14. The filtration and pumping device126is arranged to filter the plating solution for the central bath device124and to pump the plating solution to the electroplating apparatus14. The controlling device128is arranged to provide electronic and interface controls required to operate the electroplating system100. The controlling device128may include a power supply for the electroplating system100.

The electroplating apparatus14comprises a first electrofill module141, a second electrofill module142, a third electrofill module143, a first post-electrofill module144, a second post-electrofill module145, a third post-electrofill module146, and a robot arm147. The first electrofill module141, the second electrofill module142, and the third electrofill module143are arranged to electrofill a metal (e.g. copper) on a wafer. A wafer is processed by either the first electrofill module141, the second electrofill module142, or the third electrofill module143. After a wafer is processed, either the first post-electrofill module144, the second post-electrofill module145, or the third post-electrofill module146is arranged to perform a desired operation, such as an EBR process, backside etching, and acid cleaning, upon the wafer. In the electroplating apparatus14, the robot arm147is arranged to deliver the wafer to either the first electrofill module141, the second electrofill module142, the third electrofill module143, the first post-electrofill module144, the second post-electrofill module145, or the third post-electrofill module146in order to perform a corresponding operation.

The semiconductor apparatus16is a semiconductor front-end apparatus of the electroplating system100. The semiconductor apparatus16may also be a factory interface (FI) of the electroplating system100. The semiconductor apparatus16comprises a transfer chamber161, an annealing station162, a robot arm163, and an edge detector165. A wafer cassette164is also shown inFIG. 1. The robot arm163may be a so-called front-end robot arm. The transfer chamber161is configured to interface with the electroplating apparatus14. The transfer chamber161comprises a transfer station161aand an aligner161b. The transfer station161ais a station where the robot arm147and the robot arm163may pass wafers without going through the aligner161b. The aligner161b, however, may be arranged to align a wafer to the robot arm147in order to precision deliver the wafer to either the first electrofill module141, the second electrofill module142, or the third electrofill module143by the robot arm147. Moreover, the aligner161bmay also be arranged to align a post-electrofill wafer to the robot arm163in order to precision deliver the post-electrofill wafer to the annealing station162by the robot arm163.

The annealing station162is arranged to anneal a post-electrofill wafer. After a wafer is processed by the electroplating apparatus14, the robot arm163is arranged to transfer the wafer, i.e. the post-electrofill wafer, from the transfer chamber161to the annealing station162. After the annealing process, the robot arm163is arranged to transfer the annealed wafer to the wafer cassette164from the annealing station162. The wafer cassette164is configured to be an interface between the semiconductor apparatus16and another semiconductor system external to the semiconductor apparatus16. In the embodiments, the wafer cassette164comprises a first cassette164aand a second cassette164b.

The edge detector165is disposed over or on top of the robot arm163for the purpose of monitoring at least one portion of an edge bevel removal (EBR) area of a wafer, e.g. the wafer166as shown inFIG. 1, carried by the robot arm163. The wafer166is the post-electrofill wafer. More specifically, after the EBR process, the robot arm163is controlled to transfer the wafer166to the annealing station162from the transfer chamber161, and the edge detector165is controlled to monitor the at least one portion of the EBR area of the wafer166when the robot arm163is still carrying the wafer166. According to the embodiment, the edge detector165is arranged to monitor the EBR area of the wafer166in real-time.

FIG. 2is a diagram illustrating the electroplating system100in which a processing flow of a wafer is included in accordance with some embodiments. The processing flow is illustrated by a series of arrow symbols indicated by201,202,203,204,205, and206respectively. When a wafer is loaded into one of the cassettes164aand164bin the wafer cassette164, the robot arm163is arranged to deliver the wafer to the transfer station161aof the transfer chamber161, i.e. the arrow201. The robot arm163may be configured to use a vacuum attachment technique to hold the wafer. It is noted that the robot arm163may also deliver the wafer to the aligner161bif the wafer needs to be aligned with the robot arm147.

According to the embodiments, the wafer is then delivered to the first electrofill module141by the robot arm147, i.e. the arrow202. It is noted that the wafer may be delivered to either the first electrofill module141, the second electrofill module142, or the third electrofill module143. In the first electrofill module141, the wafer may be electrofilled with a metal, such as copper. Electrolytes in the central bath device124may be used to perform the electrofill process.

After the electrofill process, the wafer is delivered to the second post-electrofill module145by the robot arm147in order to remove the unwanted copper layer on the edge bevel region of the wafer, as indicated by an arrow203. The unwanted copper layer may be etched away by an etchant solution. The second post-electrofill module145may also clean, rinse, and/or dry the wafer. It is noted that the wafer may be delivered to either the first post-electrofill module144, the second post-electrofill module145, or the third post-electrofill module146in order to perform the EBR process.

When the EBR process completes, the wafer is delivered to the aligner161bof in the transfer station161afrom the second post-electrofill module145by the robot arm147, as indicated by an arrow204. It is noted that the robot arm147may deliver the wafer to the transfer chamber161.

According to the embodiments, the wafer (i.e.166) in the aligner161bis then delivered to the annealing station162by the robot arm163, as indicated by an arrow205. During the delivery of the wafer166, the edge detector165captures an image of the at least one portion of the EBR area of the wafer166so as to monitor the wafer166in real time. More specifically, when the wafer166is positioned in the aligner161b, the robot arm163stretches out to reach the aligner161b. After holding the wafer166, the robot arm163pulls back. Then, the robot arm163stretches out again to deliver the wafer166to the annealing station162. As shown inFIG. 2, the dotted line arrow207is the transferring route of the wafer166delivered from the aligner161bto the annealing station162. The transferring route may be the predetermined route set by the manufacturer of the electroplating system100. The wafer166will pass through a predetermined location208under or near the edge detector165. When the wafer166reaches the predetermined location208, the edge detector165is triggered to capture the image of the at least one portion of the EBR area of the wafer166. It is noted that the predetermined location208can be any appropriate location between the robot arm163and the edge detector165.

The image is directly sent to a processing device, either internal or external, to the electroplating system100. The processing device is arranged to analyze the image for inspecting the EBR area of the wafer166in real time. Moreover, the edge detector165may be installed in anywhere above the robot arm163as long as the edge detector165can capture the image of the at least one portion of the EBR area of the wafer166. It is noted that the edge detector165is not installed in the transfer chamber161.

When the annealing process in the annealing station162completes, the robot arm163delivers the annealed wafer to one of the cassettes164aand164b, as indicated by a dotted arrow206. The annealing station162may include a furnace. The annealed wafer in the wafer cassette164is then delivered to other systems, such as a chemical mechanical polishing system for further processing.

According to the embodiments, the edge detector165comprises a charge-coupled device (CCD) camera301for capturing the image of the at least one portion of the EBR area of the wafer166by the charge-coupled technique. The edge detector165further comprises an illuminant device302for illuminating the at least one portion of the EBR area of the wafer166.FIG. 3is a simplified diagram illustrating a configuration of the CCD camera301, the illuminant device302, and the wafer166in accordance with some embodiments. The illuminant device302is controlled to illuminate the at least one portion of the EBR area of the wafer166with red light, for example, when the CCD camera301captures the image of the at least one portion of the EBR area of the wafer166. The illuminant device302may output oblique light to the at least one portion of the EBR area as shown inFIG. 3.

FIG. 4is a real picture illustrating a portion of the wafer166in accordance with some embodiments. The portion of the wafer166comprises the active area401and the EBR area402of the wafer166. The CCD camera301is arranged to capture the image of the area in the block403in which a portion of the active area401and a portion of the EBR area402are within the block403. Therefore, the illuminant device302is controlled to illuminate at least the area in the block403of the wafer166when the CCD camera301captures the image in the block403.

In addition, to precisely analyze the EBR area402of the wafer166, more than one portion (e.g. two or more different portions) on the EBR area402are monitored. According to the embodiments, the CCD camera301comprises a first CCD sensor and a second CCD sensor in order to capture images of a first portion and a second portion on the EBR area402respectively.FIG. 5is a simplified diagram illustrating the edge detector165in the semiconductor apparatus16in accordance with some embodiments. The edge detector165comprises a first CCD sensor501, a second CCD sensor502, and an illuminant device503. The first CCD sensor501is arranged to capture an image of a first portion504of an EBR area505of a wafer506. The second CCD sensor502is arranged to capture an image of a second portion507of the EBR area505of the wafer506. The first portion504and the second portion507are two different portions of the EBR area505. The first CCD sensor501and the second CCD sensor502are installed in two different positions above the robot arm (not shown inFIG. 5) for carrying the wafer506so as to clearly capture the images of first portion504and the second portion507. It is noted that the EBR area505is roughly the area near the outer boundary of the wafer506.

The illuminant device503is installed substantially above in the semiconductor apparatus16for the purpose of illuminating the first portion504and the second portion507of the EBR area505. More specifically, when the wafer506carried by the robot arm (not shown inFIG. 5) reaches the predetermined location, the illuminant device503is activated to illuminate the first portion504and the second portion507such that the first CCD sensor501and the second CCD sensor502can better capture the images of the first portion504and the second portion507, respectively. In the embodiments, the illuminant device503illuminates the first portion504and the second portion507with a red light. However, this is not a limitation of the embodiments. The illuminant device503may illuminate other suitable back light for the first portion504and the second portion507.

In addition, although only one illuminant device503is shown inFIG. 5, this is not a limitation of the embodiments. The illuminant device503may comprise two separate illuminant devices so as to illuminate the first portion504and the second portion507of the EBR area505, respectively. By doing so, the first CCD sensor501and the second CCD sensor502are more capable of capturing the images of the first portion504and the second portion507, respectively.

According to the embodiments, the first portion504and the second portion507are symmetrically located on the EBR area506. For example, when the first portion504is located on the rightmost area of the EBR area506, the second portion507may be located on the leftmost area of the EBR area506. However, this is not a limitation of the embodiments. The first portion504and the second portion507may be any two different portions on the EBR area505as long as the EBR area505of the wafer506can be successful inspected and analyzed by the above-mentioned processing device according to the captured images.

InFIG. 5, a controlling device508is also shown. The controlling device508is arranged to control the operation of the first CCD sensor501, the second CCD sensor502, and the illuminant device503. The controlling device508may be installed in a semiconductor apparatus (i.e. the semiconductor apparatus16) or incorporated with the above-mentioned controlling device128. Alternatively, the controlling device508may be externally set up to provide control signals to an electroplating system (i.e. the electroplating system100).

When the images of the first portion504and the second portion507of the EBR area505are captured by the first CCD sensor501and the second CCD sensor502, respectively, the image data is transmitted to a personal computer (PC)509in order to measure the widths of the EBR area505in the first portion504and the second portion507of the wafer506. The PC509may comprise a monitor or a screen in order to display, in real time, the images captured by the first CCD sensor501and the second CCD sensor502together with the measured widths of the EBR area505. The measured widths are then transmitted to a fault detection and classification (FDC) system510in order to determine if any abnormal etching edge occurs in the EBR area505. The PC509may transmit data in the form of SECS-II code to the FDC system510.

The FDC system510is a computer integrated manufacturing (CIM) FDC system capable of automatically detecting and classifying the errors found in the EBR area505. When an error is found in the EBR area505, the FDC system510may send an alarm signal to alert the manufacturer. Therefore, the embodiments inFIG. 5can monitor, in real time, the EBR area505of the wafer506in the semiconductor apparatus16. Moreover, the FDC system510may collect the width of the EBR area of each wafer processed by the electroplating apparatus (i.e. the electroplating apparatus14) so as to evaluate or track the performance of the electroplating system (i.e. the electroplating system100).

In an embodiment, the images of the first portion504and the second portion507of the EBR area505captured by the first CCD sensor501and the second CCD sensor502are in relatively high digital resolution, and thus the width of the EBR area505can be precisely determined. For example, the first CCD sensor501and the second CCD sensor502capture a full-color image of the first portion504and the second portion507in order to generate the image data. In that case, the first CCD sensor501and the second CCD sensor502are configured to not only sense the grayscale information of the first portion504and the second portion507.

In some embodiments, the PC509and the FDC system510may be externally set up. However, this is not a limitation of the embodiments. In other embodiments, some of the components of the PC509and the FDC system510may be installed in the semiconductor apparatus (i.e. the semiconductor apparatus16) or incorporated with the above-mentioned controlling device128.

FIG. 6is a real picture illustrating a first image601and a second image602of an EBR area in accordance with some embodiments. The first image601and the second image602are the real-time images of the wafer506captured by the first CCD sensor501(i.e. CCD1) and the second CCD sensor502(i.e. CCD2), respectively. The first image601and the second image602are displayed on the monitor of the PC509. The first image601shows the first portion504of the EBR area505while the second image602shows the second portion507of the EBR area505. Moreover, the first image601shows the measured position603and a measured width of approximately 2.23 mm of the EBR area505in the first portion504. The second image602shows the measured position604and a measured width of approximately 2.23 mm of the EBR area505in the second portion507. The PC509comprises a processing device used to automatically detect and measure the widths of the EBR area505in the first portion504and the second portion507. It is noted that the numerals605and606in the first image601and the second image602represent the useable areas (or active areas) of the wafer506.

FIG. 7is a real picture illustrating a semiconductor apparatus700in accordance with some embodiments. The semiconductor apparatus700comprises a robot arm701, a wafer702, a trigger device703, a first illuminant device704, a second illuminant device705, a first CCD sensor706, and a second CCD sensor707. It is noted that the robot arm701, the wafer702, the first and second illuminant devices704,705, the first CCD sensor706, and the second CCD sensor707are similar to the above-mentioned robot arm163, the wafer166, the illuminant device503, the first CCD sensor501, and the second CCD sensor502, respectively, thus the detailed description is omitted here for brevity. In comparison with the embodiments inFIG. 5, the semiconductor apparatus700further comprises the trigger device703. The trigger device703is arranged to activate the first CCD sensor706and the second CCD sensor707so as to capture the images of a first portion708and a second portion709on the wafer702when the trigger device703determines that a distance D between the trigger device703and the robot arm701reaches a predetermined distance Dp. Moreover, when the trigger device703determines that the distance D between the trigger device703and the robot arm701is substantially equal to the predetermined distance Dp, the trigger device703also activates the first illuminant device704and the second illuminant device705in order to illuminate the first portion708and the second portion709such that the first CCD sensor706and the second CCD sensor707can clearly capture the images of the first portion708and the second portion709, respectively. The trigger device703is configured to use a laser beam to determine the distance D between the trigger device703and the robot arm701. However, this is not a limitation of the embodiments.

According to the embodiments, when the robot arm701carries the wafer702to the annealing station (not shown inFIG. 7) from the aligner (not shown inFIG. 7), and when the wafer702reaches the predetermined position where the first CCD sensor706and the second CCD sensor707can clearly capture the images of the first portion708and the second portion709, respectively, the distance D between the trigger device703and the robot arm701is the predetermined distance Dp. For example, the predetermined position may be a position where the first portion708and the second portion709are right below the first CCD sensor706and the second CCD sensor707, respectively. Therefore, once the trigger device703detects that the distance D is the predetermined distance Dp, the trigger device703activates the first illuminant device704, the second illuminant device705, the first CCD sensor706, and the second CCD sensor707. It is noted that the first illuminant device704and the second illuminant device705may be activated slightly earlier than the first CCD sensor706and the second CCD sensor707. After the first CCD sensor706and the second CCD sensor707capture the images of the first portion708and the second portion709, respectively, the first illuminant device704and the second illuminant device705may be turned off until the next wafer reaches the predetermined position.

In some embodiments, the transferring route (e.g. the dotted line arrow207inFIG. 2) of the wafer702delivered from the aligner to the annealing station is the predetermined route set by the manufacturer of the semiconductor apparatus700. Moreover, the first CCD sensor706and the second CCD sensor707are installed above the predetermined route so as to capture the images of the first portion708and the second portion709, respectively, when the wafer702passes a predetermined position on the predetermined route. Therefore, the operation of capturing the images of the first portion708and the second portion709does not delay the preset speed of the robot arm701, and the present embodiments do not impact the wafer throughput of the electroplating system.

FIG. 8is a flow diagram illustrating a method800for inspecting a wafer in accordance with some embodiments. Referring toFIG. 8, in operation802, a wafer is transferred to an annealing station from a transfer chamber by a front-end robot arm.

In operation804, a distance between a trigger device and the front-end robot arm is detected. If the distance is a predetermined distance, meaning that the wafer reaches a predetermined location, then the method800goes to operation806. If the distance is not the predetermined distance, meaning that the wafer does not reach the predetermined location, then the method800goes back to operation804.

In operation806, a first illuminant device and a second illuminant device are activated to illuminate a first portion and a second portion of an EBR area of the wafer respectively.

In operation808, a first CCD sensor and a second CCD sensor are activated to capture the images of the illuminated first and second portions.

In operation810, the images of the first portions and the second portions together with the measured widths of the corresponding EBR areas are displayed on a PC in real time.

In operation812, the measured widths corresponding to the wafer are transmitted to an FDC system to determine if any abnormal etching edge occurs in the EBR area. The operation of method800can be referred to the operation of the embodiments as shown inFIG. 1,FIG. 2,FIG. 5, and/orFIG. 7, wherein the detailed description of the method800is omitted here for brevity.

Briefly, according to the embodiments, the edge detector is installed above a robot arm in the semiconductor apparatus in order to capture the images of the EBR area when the robot arm transfers the wafer to the annealing station from the transfer station. Thus, the edge detector does not impact the wafer throughput of the electroplating system. In addition, the edge detector uses a CCD camera(s) to capture the images of the EBR area illuminated by an illuminant device. The captured images are processed and analyzed by a computer to detect, in real-time, the abnormal width of the EBR area. Moreover, when the EBR area is captured by the CCD camera, the captured image can be in high digital resolution, and thus the width of the EBR area can be precisely determined to reduce the false alarm rate.

In some embodiments, a semiconductor apparatus includes a transfer chamber, an annealing station, a robot arm, and an edge detector. The transfer chamber is configured to interface with an electroplating apparatus. The annealing station is arranged to anneal a wafer. The robot arm is arranged to transfer the wafer from the transfer chamber to the annealing station. The edge detector is disposed over the robot arm for the purpose of monitoring at least one portion of an edge bevel removal area of the wafer carried by the robot arm.

In some embodiments, a method for inspecting a wafer includes: transferring the wafer from a transfer chamber to an annealing station by a robot arm; and monitoring at least one portion of an edge bevel removal area of the wafer over the robot arm when the wafer is transferred from the transfer chamber to the annealing station.

In some embodiments, an electroplating system includes an electroplating apparatus and a semiconductor apparatus. The electroplating apparatus is arranged to electroplate a wafer. The semiconductor apparatus includes a transfer chamber, an annealing station, a robot arm, and an edge detector. The transfer chamber is arranged to interface with the electroplating apparatus. The annealing station is arranged to anneal the wafer. The robot arm is arranged to transfer the wafer from the transfer chamber to the annealing station. The edge detector is disposed over the robot arm for the purpose of monitoring at least one portion of an edge bevel removal area of the wafer carried by the robot arm.