Dual-function wafer handling apparatus

A dual-function wafer handling apparatus for handling a wafer includes an aligner for rotating the wafer, an ID reader disposed corresponding to an edge of the wafer for reading an ID of the wafer, and an optical defect inspection unit for capturing images to analysis.

BACKGROUND

A conventional semiconductor fabrication plant typically includes multiple fabrication areas or stations interconnected by a bay. Each station generally includes the requisite fabrication tools to provide a particular semiconductor manufacturing process, such as photolithography, chemical-mechanical polishing, chemical vapor deposition, etc.

In the semiconductor manufacturing processes described above, defect inspection is carried out in some manufacturing processes. In the defect inspection, the surface of the semiconductor wafer is inspected to see if there are scratches, dust, cracks, stains or uneven portions manually. Defects such as cracks may result in the breaking of the wafer itself. Therefore, the presence or absence of defects at the wafer edge portion has to be detected as early a step as possible to determine whether the wafer is good or bad.

DETAILED DESCRIPTION

Conventionally, the wafer is manually inspected by an operator at an automated optical inspection (AOI) station, or set run-card for vis-edge tool offline check with a long time. Conventional wafer defect inspection not only spends lots of time, but also requires extra stations and operators. Furthermore, the conventional manual inspection only selects several wafers as samples among a wafer lot. The sampling rate of the conventional manual inspection is, for example, about 5%. Namely, only 5% of wafers have been edge-defect inspected during the semiconductor manufacturing processes.

In order to detect the defects at the wafer edge portion more efficiently, the present disclosure integrates a wafer defect detector with an inline apparatus for automatically detecting defects at the edge of the wafer at the same time of that the wafer is processed. Therefore, wafers need not be moved to an additional manual inspection station thereby reducing manual operations, and the sampling rate of the wafers is highly increased.

The inline apparatus is a regular apparatus, which processes almost every wafer. For example, in the manufacturing of a semiconductor device, the wafer or device is usually processed at many work stations or processing machines. The transporting or conveying system, such as an automatic material handling system (AMHS) has been used extensively in the semiconductor fabrication field. Therefore, the inline apparatus with wafer defect inspection function can be one of stations of the automatic material handling system.

The automatic material handling system includes a plurality of bays (rows) of storage areas. Each bay has a stocker, which includes bins for holding a plurality of containers or front opening unified pods (FOUPs). The stocker holds the containers or FOUPs in preparation for transporting a container or FOUP to the loadport of a processing tool. The automatic material handling system can divide wafers into lots that undergo different processing sequences.

FIG. 1is a schematic diagram of a dual-function wafer handling apparatus, in accordance with some embodiments. The dual-function wafer handling apparatus100is one of the stations in the automatic material handling system. The dual-function wafer handling apparatus100includes an aligner110, an ID-reader120, an optical defect inspection unit130, a frame140for fastening the aligner110, the ID-reader120and the optical defect inspection unit130, and a control unit150for controlling the aligner110and the ID reader120. The dual-function wafer handling apparatus100is arranged near a stocker for sorting and inspecting wafers200.

The wafers200fabricated in the semiconductor fabrication process each has their own IDs, which are located opposite a notch or an orientation flat at the wafers200. The IDs are data matrix codes which contain a lot number and a barcode, and are formed on the wafers200by a laser. The IDs of each wafer200are different from each other to allow easy recognition of the wafers200. The dual-function wafer handling apparatus100with the aligner110and the ID reader120can recognize automatically the ID of the wafer200. The aligner110includes a motor112, and a rotatable disk114driven by the motor112. The wafer200is transferred and placed on the rotatable disk114. For example, the wafer200is transferred from a FOUP to the aligner110by a robot arm. When the control unit150detects that the wafer200is positioned on the rotatable disk114, the control unit150sends a command to trigger the aligner110. The aligner110rotates the wafer200at a constant rotating speed and detects the center position of the wafer200and the direction in which the notch or the orientation flat is present. Therefore, the wafer200is aligned on the aligner110. The image of the ID of the wafer200, which is formed opposite to the notch or the orientation of the wafer200, is captured and identified by the ID reader120, then the ID information of the wafer200is sent to the control unit150for later sorting.

Also, after the wafer200is aligned on the aligner110, the control unit150sends a command to initial the optical defect inspection unit130. The optical defect inspection unit130includes an image sensor132and an automatic optical inspection processor134. The image sensor132is, for example, a charge-coupled device (CCD). The image sensor132is triggered by the optical inspection processor134to capture images of the edge of the wafer200while the wafer200is rotated by the rotatable disk114. The images captured by the image sensor132are sent to the optical inspection processor134for analysis. The rotating speed of the rotatable disk134can be controlled according the image capturing frequency of the image sensor132. If the analysis result of the images of the edge of the wafer200is normal, that means the wafer200passes the inspection, and the wafer200is conveyed to the next process from the aligner110. However, if the analysis result of the images of the edge of the wafer200is abnormal, that means the wafer200has defects and cannot pass the inspection, and the dual-function wafer handling apparatus100sends an alarm to tell operator the failed wafer200needs to be removed.

The frame140includes a platform142, a rod144standing next to the platform142, and a first holder146and a second holder148fastened on the rod144. The second holder148is arranged higher than the first holder146. The aligner110is placed on the platform142. The ID reader120is placed on the first holder146, and the image sensor132is placed on the second holder148. In some embodiments, the image sensor132is fastened at a side or a bottom of the second holder148. The ID reader120and the image sensor132are located corresponding to the edge of the wafer200for capturing images of the edge of the wafer200. In some embodiments, the ID reader120and the image sensor132are arranged at opposite sides of the wafer200. For example, the ID reader120is disposed under the wafer200, and the image sensor132is disposed above the wafer200. Namely, the wafer200is disposed between the ID reader120and the image sensor132. The ID reader120reads the ID from the bottom of the wafer200after the notch or orientation flat is found on the wafer200. The image sensor132captures images of the edge of the wafer200when the wafer200is rotated by the aligner110.

The dual-function wafer handling apparatus100provides functions of automated sorting and automated defect inspection. The dual-function wafer handling apparatus100is one of the stations in the automatic material handling system, which is widely used in the semiconductor fabrication plant. Therefore, each wafer200of the wafer lots can be inspected automatically while being sorted. The sampling rate of the wafers200becomes 100%, and no extra outline inspection station is needed.

By using the dual-function wafer handling apparatus100discussed above, during the observation of the edge of the wafer200, adjustment can be made to the wafer200position so that the edge of the wafer200can be located at the position under the image sensor132, and adjustment can be made to the rotating speed to adjust the observation speed. For example, in some embodiments, the time for one-round wafer rotation is about 1 second; the image capturing frequency of the image sensor132is about 65 frames per second; and the view of field is about 43*32 mm2. The image sensor132captures the images continuously while the wafer200is rotated by the aligner110. Because the ID reader120identifies the wafer200at the same time while the image sensor130captures the images, the wafer200rotates at least one round on the aligner110. Therefore, the image sensor132can capture images of complete circumference of the wafer200. The plurality of images have overlapping regions of the wafer200.

FIG. 2andFIG. 3are image and analysis result of an example of a normal wafer. The images of the edge of the wafer are captured by the image sensor and are sent to the optical inspection processor for analysis. The optical inspection processor captures the profile of the wafer and calculates the curvature of the wafer at each frame. The data of the curvatures of frames are collected, such that the analysis result shown inFIG. 3is provided. The normal wafer has a smooth and continuous curved profile. Namely, the curvature of the profile of the normal wafer (excluding the notch portion) can be regarded as constant inFIG. 3.

FIG. 4andFIG. 5are image and analysis result of an example of an abnormal wafer. The images of the edge of the wafer are captured by the image sensor and are sent to the optical inspection processor for analysis. However, the profile of the abnormal wafer is not smooth and continuous, thus the curvature of the abnormal wafer is not constant. For example, there are two concave areas and at the edge of the wafer, one is a notch A, and the other one is a chipping B. The notch A is arranged opposite to the ID of the wafer in order to identify the position of the ID more easily. The profile of the notch A is predetermined, thus the curvature A′ of the notch A is predetermined and regular inFIG. 5. However, the defects, such as the chipping B, at the wafer have various types and various shapes, thus the profile of the abnormal wafer is broken. For example, the curvature B′ of the abnormal wafer at the chipping B is irregular inFIG. 5.

As discussed fromFIG. 2toFIG. 5, the images of the complete circumference of the wafer are captured by the image sensor, and the profiles of the wafer in the images are calculated thereby obtaining the curvature of the wafer. The curvature of the wafer at the defect is irregular and can be distinguished from the curvature of the notch. When the optical inspection processor detects the irregular curvature, the wafer is determined abnormal and fails the inspection. Defects existing on the edge of the circumference of the wafer, such as wafer chipping, cracks, and a rinse cut amount, can be detected by this manner, and the abnormal wafer is early detected and is prevented from being made in the photolithography step executed after the application of photoresist.

Reference is made back toFIG. 1. In some embodiments, the dual-function wafer handling apparatus100is a sorter integrated with an automatic optical defect inspection unit. The sorter itself is an inline apparatus and is widely utilized in the semiconductor fabrication field. Almost each and every wafer200is processed by the sorter for being identified and conveyed to the predetermined station. By using the dual-function wafer handling apparatus100, the process of inspection defects on the wafer200is made automatically while the wafer200is sorted. Therefore, the wafer200needs not be moved to an outline apparatus, and the sampling rate of wafer inspection is raised to about 100%. Namely, the wafer defect inspection is made inline the fabricating process, and the inspection result can report to the operator.

The dual-function wafer handling apparatus100further includes a warning device160. The warning device160is electrically connected to the control unit150. The analysis result of the optical inspection processor134is sent to the control unit150. If the analysis result provided by the optical inspection processor134is normal, that means the wafer200on the aligner110passes the inspection, and the wafer200can go to next process according to the ID information provided by the ID reader120. For example, the wafer200is moved from the aligner110to the FOUP. If the analysis result provided by the optical inspection processor134is abnormal, that means the wafer200does not pass the inspection, and the control unit150sends a signal to trigger the warning device160in order to tell the operator to remove the wafer200with defects.

The warning device160can be, for example, a sound alarm and/or an optical alarm. The quantity of the sound and/or the light generated by the warning device160is great enough to warn the operator that the wafer200processed by the dual-function wafer handling apparatus100is with defects. The wafer200with defects would stay on the aligner110until the operator shuts down the warning device160and removes the wafer200with defects.

The dual-function wafer handling apparatus100optionally includes a light source170. The light source170is also disposed on the second holder148. The light source170is disposed close to the image sensor132in order to provide lights to the wafer200for improving the quality of images captures by the image sensor132. In some embodiments, the light source170is a co-axial light source providing co-axial lights with the image sensor132to the wafer200. The positions of the image sensor132and the light source170can be adjusted via the frame140. In some embodiments, the dual-function wafer handling apparatus100further includes an objective lens disposed in front of the image sensor132. The image sensor132captures images through the use of the objective lens. When the edge portion of the wafer200is inspected, the edge portion of the wafer200is adjusted for being under the objective lens. After the wafer edge portion is adjusted to the position under the objective lens in this manner, the image sensor132begins to capture images. The images of the wafer edge portion obtained with the image sensor132are sent to the optical inspection processor134for analysis as discussed previously.

FIG. 6is an oblique view of the frame of the dual-function wafer handling apparatus100, according to some embodiments. The frame140includes the platform142, the rod144, the first holder146, and the second holder148. The platform142is utilized for placing the aligner thereon. The rod144is disposed next to the platform142. The first holder146and the second holder148are fastened on the rod144. The second holder148is arranged higher than the first holder146. In some embodiments, the first holder146is utilized for placing the ID reader thereon, and the second holder148is utilized for placing the image sensor and the light source thereon. In some embodiments, the first holder146is utilized for placing the image sensor and the light source thereon, and the second holder148is utilized for placing the ID reader thereon. The heights of the first holder146and the second holder148can be adjusted, such that the first holder146and the second holder148are both disposed under the aligner, or the first holder146and the second holder148are both disposed above the aligner, or the first holder146and the second holder148are disposed at opposite sides of the aligner.

The position of the first holder146and the second holder148on the rod144can be adjusted. For instance, the rod144is a lead screw, and the first holder146and the second holder148are fastened on the rod144with the retaining nuts141and washers143, in which the retaining nuts141are screwed or clamped on the rod144and the washers143are arranged between the retaining nuts141and the first holder146or the second holder148. The first holder146and the second holder148are moved to the predetermined position and are supported by the retaining nuts141. The position of the first holder146and the second holder148can be adjusted by releasing the retaining nuts141, changing the position of the first holder146and the second holder148, and re-fastening the retaining nuts141.

The material of the rod144, the first holder146, the second holder148, the retaining nuts141and the washers143is metal. In some embodiments, the rod144is made of steel, and the first holder146, the second holder148, the retaining nuts141and the washers143are made of aluminum alloy.

In some embodiments, the frame140further includes plural bolts145for fastening the first holder146and the second holder148to the washers143. For example, the washer143has screw holes1432thereon, and the first holder146has plural through holes1462thereon. The bolts145pass through the through holes1462and screwed with the screw holes1432, such that the first holder146is fastened on the washer143. Similarly, the second holder148has plural through holes1482thereon, and the bolts145pass through the through holes1482and screwed with the screw holes1432, such that the second holder148is fastened on the washer143.

In some embodiments, the length of the first holder146and the second holder148can also be adjusted to fit the size of the image sensor and the ID reader. The first holder146includes a plate portion1464and a flange portion1466. The plate portion1464has the through holes1462and is supported by the retraining nuts141and washer143. The flange portion1466has flanges. Both the plate portion1464and the flange portions1466have slots1468thereon. The bolts and the nuts can be utilized for screwing the plate portion1464and the flange portion1466. The screwing position in the slots1468can be changed to change the relative position between the plate portion1464and the flange portion1466, such that the length of the first holder146can be adjusted. Similarly, the second holder148includes a plate portion1484and a flange portion1486. The plate portion1484has the through holes1482and is supported by the retraining nuts141and washer143. The flange portion1486has flanges, and the image sensor is fastened at the flange portion1486. Both the plate portion1484and the flange portions1486have slots1488thereon. The bolts and the nuts can be utilized for screwing the plate portion1484and the flange portion1486. The screwing position in the slots1488can be changed to change the relative position between the plate portion1484and the flange portion1486, such that the length of the second holder148can be adjusted.

The frame140provides horizontal adjusting function to the first holder146and the second holder148via changing the position of the retaining nuts141fastened at the rod144. The frame140also provides vertical adjusting function to the first holder146and the second holder148via changing the screwing position between the plate portions1464,1484and the flange portion1466,1486. Since the horizontal position and the vertical position of the first holder146and the second holder148can be adjusted, the arrangement of the first holder146and the second holder148is more flexible. Thus the image sensor and the ID reader on the first holder146and the second holder148can be arranged corresponding to the edge of the wafer.

FIG. 7is a flow chart of a method for handling a wafer, according to some embodiments. The method uses an inline apparatus to handle the wafer. The method includes step S10and step S20. In step S10, the wafer is sorted at a station of an automatic material handling system, for example, by an ID reader automatically. In step S20, the wafer is defect inspected at the same station by an image sensor automatically. Therefore, the station utilized in the method provides both functions of sorting and defect inspection. The steps S10and S20can be performed individually or simultaneously. In some embodiments, the wafer is inspected when sorting the wafer.

The present disclosure provides a dual-function wafer handling apparatus. The dual-function wafer handling apparatus is an apparatus with an aligner and provides the function of defect inspection. The defects of the wafer are inspected by capturing the profile of the wafer and analysis the curvature of the wafer. In some embodiments, the dual-function wafer handling apparatus provides both functions of sorting and defect inspection. The functions of sorting and the defect inspection are performed by the dual-function wafer handling apparatus automatically. Thus the sampling rate and accuracy of wafer defect inspection are highly improved. In some embodiments, the act of sorting is made when the defect inspection process is preformed. The dual-function wafer handling apparatus is an inline apparatus. Therefore, the wafer needs not be moved to an outline station for inspection. For example, the dual-function wafer handling apparatus can be a station of the automatic material handling system. The automatic material handling system is widely utilized in the semiconductor plant. Therefore, no extra station is required for wafer defect inspection. The frame for assembling the image sensor and the ID reader is adjustable. The position of the image sensor and the ID reader can be adjusted vertically and horizontally, such that the image sensor and the ID reader are positioned corresponding to the edge of the wafer.

According to some embodiments, an aspect of the disclosure provides a dual-function wafer handling apparatus for handling a wafer. The apparatus includes an aligner for rotating the wafer, an ID reader disposed corresponding to an edge of the wafer for reading an ID of the wafer, and an optical defect inspection unit for capturing images to analysis.

According to some embodiments, an aspect of the disclosure provides a dual-function wafer handling apparatus for handling a wafer. The apparatus includes an aligner for rotating the wafer, an ID reader for reading an ID of the wafer, an image sensor for capturing an image of an edge of the wafer, an optical inspection processor for capturing a profile of the edge of the wafer and calculating a curvature of the profile for analysis, and a frame for arranging the ID reader and the image sensor corresponding to the edge of the wafer.

According to some embodiments, an aspect of the disclosure provides method for handling a wafer. The method includes sorting the wafer at a station of an automatic material handling system automatically, and inspecting defects of the wafer at the same station automatically.