Image based substrate mapper

Methods and apparatus for detecting warpage in a substrate are provided herein. In some embodiments, a warpage detector for detecting warpage in substrates includes: one or more light sources to illuminate one or more substrates when present; a camera for capturing images of exposed portions of one or more substrates when present; a motion assembly having a mounting stage for supporting the camera; and a data acquisition interface (DAI) coupled to the camera to process substrate images and detect warpage of substrates based upon the processed substrate images.

FIELD

Embodiments of the present disclosure generally relate to substrate manufacturing processes.

BACKGROUND

With the persisting need for better, smaller, faster, and more reliable electronics' goods, substrate manufacturers must produce good quality and reliable substrates at increasing processing speeds. Substrate manufacturing typically involves substrate mapping for detecting substrate absence, substrate misplacement, substrate cross-slotting, substrate double-slotting, and other similar substrate placement errors common in cassettes and Front Opening Unified Substrate storage cassettes (FOUPs).

Current substrate mapping technologies, such as optical mapping sensors, are typically provided as stand-alone devices or as part of edge (or vacuum) grip end-effectors. The current substrate mapping devices and methods are typically used to map substrates that may have varying coatings, edge geometries, and thicknesses. However, the inventors have discovered that the current substrate mapping devices and methods are poor in detecting substrate warpage and thus fail to sustain acceptable process yields.

Therefore, the inventors have provided improved apparatus and methods for timely and accurately detecting substrate warping.

SUMMARY

Methods and apparatus for detecting warpage in a substrate are provided herein. In some embodiments, a warpage detector for detecting warpage in substrates includes: one or more light sources to illuminate one or more substrates when present; a camera for capturing images of exposed portions of one or more substrates when present; a motion assembly having a mounting stage for supporting the camera; and a data acquisition interface (DAI) coupled to the camera to process substrate images and detect warpage of substrates based upon the processed substrate images.

In some embodiments, a substrate processing system includes: one or more process chambers; a transfer chamber; a pair of load lock chambers; a plurality of substrate storage cassettes having a front opening and configured to receive and hold a plurality of substrates; a substrate storage cassette loader to shuttle cassettes of substrates between the load lock chambers and the plurality of substrate storage cassettes; and a warpage detector for detecting warpage of substrates in the plurality of substrate storage cassette. The warpage detector may be as in any of the embodiments described herein.

In some embodiments, a method for detecting warpage in a substrate for processing includes: (a) capturing an image of an edge of the substrate; (b) processing the image of the edge of the substrate; and (c) determining an extent of warpage in the substrate from the processed image.

DETAILED DESCRIPTION

Embodiments of the present disclosure include a system and method for detecting the warpage of substrates contained in substrate storage cassettes (e.g., FOUPs) prior to performing one or more processes on the substrates. The inventors have observed that current substrate mapping methods and apparatus are focused on mapping the planar principal surfaces of substrates (e.g., x-y plane of substrate) and fail to detect substrate warpage out of the x-y plane along the z axis. Such warpage may be due, for example, to deformities along the side edge of the substrate.

According to embodiments consistent with the present disclosure, a warpage detector is provided and used to measure and analyze the warpage of the substrate prior to performing one or more processes on the substrates. Accordingly, embodiments of the present disclosure improves substrate processing by saving processing time and materials that may be otherwise expended on unacceptably warped substrates.

FIG. 1is a schematic view of a warpage detector100in accordance with one or more embodiments of the present disclosure. The warpage detector100includes a high resolution camera102, one or more light sources104, a motion assembly106, and a data acquisition interface (DAI)108.

The high resolution camera102generally includes a focus lens110and a viewfinder112. The focus lens110is provided to resolve and capture side views of substrates having thicknesses between about 300 micrometers and about 3000 micrometers, or in some embodiments, between about 300 micrometers and about 800 micrometers. In some embodiments, the high resolution camera102may be configured to be advantageously smaller and lighter than the motion assembly106and components thereof. For example, the high resolution camera102may have a mass of less than about 300 grams.

The one or more light sources104are provided to illuminate a portion of one or more substrates (e.g., substrates208, discussed below) to be photographed with the high resolution camera102. The light sources104are configured to deliver diffuse light. For example, the light sources104may comprise light emitting diodes (LEDs) or the like. The light sources104are advantageously shaped to promote light diffusion. For example, the light sources104may be bar or ring shaped diffusive light bulbs. In some embodiments, the light sources104are disposed proximate the one or more substrates to be photographed (e.g., substrates208, discussed below). In some embodiments, the light sources104are disposed proximate the high resolution camera102. For example, as depicted inFIG. 1, the light sources104may be disposed above the viewfinder112.

The motion assembly106includes a vertical support114, a mounting stage116, and an actuator118. The vertical support114is a support and a pivot for the mounting stage116. The mounting stage116is configured to hold and support the high resolution camera102both when the resolution camera is in operation and when the mounting stage116moves the mounting stage116in one or more directions. The actuator118provides vertical motion to the mounting stage116, up and down the vertical support, as represented by directional arrow120. The actuator further provides laterally rotational motion to the mounting stage, as represented by the directional arrow122.

The data acquisition interface (DAI)108is communicatively coupled to the high resolution camera102. The DAI108includes an image processor124, a data storage device125, and a user interface126. The image processor124contains at least an image processing algorithm128and an image data analyzer130. The user interface126includes a user input shell132and an output reader134.

Upon execution, the image processing algorithm128processes substrate images captured with the high resolution camera102by converting the substrate images into image data that can be interpreted by the image data analyzer130. For example, the image processing algorithm128may convert a substrate image into pixels of binary data. For example, the image data may be in matrix or table form. In some embodiments, the image processing algorithm128may further include photograph improvement processes such as image noise filtering, or the like.

The image data analyzer130performs an analysis of the image data produced by the image processing algorithm128by comparing the image data to a warpage threshold standard. The warpage threshold standard includes lower and upper bound warpage values defined for a dimension of the photographed portion of the substrate (e.g., side photograph of substrate). In some embodiments, the warpage threshold standard may be input into the user input shell132by a user prior to beginning the mapping processes. In some embodiments, the warpage threshold standard may be pre-programmed as part of a recipe of the image processor. The warpage threshold standard is selected based on factors such as the tolerance of substrate inlets of processing chambers, and the application in which the substrates would be used.

FIG. 2shows the exemplary warpage detector100in relation to a substrate storage cassette202in accordance with one or more embodiments of the present disclosure.

The substrate storage cassette202(e.g., FOUP) has a bottom203, a front opening204, and a top205. The substrate storage cassette202further comprises an array of spaced apart slots206. Each slot206is configured to receive and support a substrate208. As illustrated in the exemplary embodiment ofFIG. 2, a total of N vertically arranged slots206may be labeled as slots206-1to206-N, from the bottom203to the top205, and configured to support substrates208, respectively labeled as substrates208-1to substrate208-N, from the bottom203to the top205. In the exemplary embodiment shown inFIG. 2, the substrate storage cassette202has N=25, vertically arranged slots206and stacked substrates208.

As illustrated by the x-y-z coordinate schematic shown on the side of the substrate storage cassette202, the edges of the substrates208exposed through the front opening204advantageously facilitates photography and analysis of the z-direction deformation, if any, for warpage detection. As discussed above, the light sources104are disposed in an area suitable to illuminate one or more substrates to be photographed by the high resolution camera. As shown inFIG. 2, the light sources104are disposed in along the front opening204, proximate the bottom203and proximate the top205, to illuminate the exposed edges of the substrates208.

Alternatively, or in combination with the actuator118, the motion assembly106may include a robotic arm.FIG. 2depicts an exemplary robotic arm210. As depicted inFIG. 2, the robotic arm210extends from a central pivot212. The central pivot includes a base213. In some embodiments, the central pivot212may be fixed to a sturdy support surface at height below the bottom203of the substrate storage cassette202, for example, a table top or a floor. The robotic arm210includes a rear end214and a blade216. The rear end214includes a mounting surface218. A mounting fixture220supports the high resolution camera102atop the mounting surface218. The mounting fixture220may be any suitable holder such as a bracket, or a clamp, or the like. The blade216can have an edge gripper222or other suitable mechanism to secure substrates thereto during transfer (e.g. during transfer of substrate208into and out of substrate storage cassette202, discussed below). In some embodiments, edge gripper222may be a vacuum gripper. The robotic arm210is configured to have vertical motion, up and down the central pivot212, as represented by directional arrow120. The robotic arm210is further configured to rotate laterally about the central pivot212and through the x-y direction facing the front opening204. For example, as depicted inFIG. 2, the robotic arm210is depicted rotated about 90 degrees clockwise from a neutral position where the camera faces a center of an exposed edge of a substrate208.

As shown inFIG. 2, the actuator118is coupled to the central pivot212to provide motion to the robotic arm210. In some embodiments, motion of the robotic arm210may include remotely controllable motion devices to allow vertical and rotational displacements of the robotic arm when the actuator is not provided.

In operation in accordance with the embodiment depicted inFIG. 2, the prior processing the substrates208, the high resolution camera102is, for example, lowered to the bottom of the substrate storage cassette202. Starting with the lowermost slot206(e.g. slot206-1), the high resolution camera102performs a continuous substrate presence scan from the bottommost slot206(e.g. slot206-1) to the topmost slot (e.g. slot206-25). When the topmost slot (e.g. slot206-25) has been scanned, the camera comes to a stop. The substrate presence scan is performed to verify if a substrate208is present in each slot206. The high resolution camera102relays the findings of the substrate presence scan to the DAI108. The substrate presence scan can also be performed in any other suitable order, such as top to bottom, or the like.

Subsequently and optionally, for example starting with a first slot—such as the topmost slot206(e.g. slot206-25)—the high resolution camera102begins capturing images of the planar principal surfaces of the substrates208(e.g., x-y planes of substrates208-25to208-1). The images may be obtained at an angle to the principal planar surface due to their location in the substrate carrier. The high resolution camera102comes to a stop after capturing the x-y plane image of the last substrate—such as the bottommost substrate (e.g. substrate208-1). Images of the planar principal surfaces of the substrates208(e.g., x-y planes of substrates208-25to208-1) are sent to the image processor124for substrate mapping. The output reader134displays and sends the x-y plane mapping results to the data storage device125. Alternatively, images of planar principal surfaces of the substrates208may be obtained in a different location (e.g., prior to loading into the cassette) and may be obtained using a different camera, with the x-y plane mapping results transmitted to the data storage device125.

Following mapping of the planar principal surfaces of each substrate208contained in the substrate storage cassette202, the height of the high resolution camera102is readjusted so that the viewfinder112is level and pointed to the center of the front facing edge of a first substrate, such as the bottommost substrate208(e.g. substrate208-1). In some embodiments, the user interface126prompts the operator to enter the warpage threshold standard parameters into user input shell132. The warpage threshold standard parameters may also be provided at an earlier stage or automatically.

Subsequently, the high resolution camera102captures an image of the facing edge of the first substrate208(e.g. substrate208-1). The high resolution camera102moves to next slot having a substrate208therein, and comes to a stop. The high resolution camera102stops at a height where the viewfinder112is level and pointed to a center of the front facing edge of a second substrate208to be photographed (e.g. substrate208-2). Subsequently, the high resolution camera102captures an image of the edge of the second substrate208(e.g. substrate208-2). Sequentially, the operation is performed for each substrate208contained in the substrate storage cassette202until an image of the front facing edge of the last substrate, such as the topmost substrate208(e.g. substrate208-25), is captured. The high resolution camera102sends the images of all the substrates (e.g. substrates208-1to208-25) present in the slots206(e.g. slots206-1to206-25) to the image processor124for processing.

In the image processor124, the image processing algorithm128processes and converts the substrate images into image data that is sent to the image data analyzer130. The image data analyzer130compares the image data to a warpage threshold standard. Following the warpage analysis, the substrate warpage results are read out and/or displayed by the output reader134in one or more forms, and sent to and stored in the data storage device125. For example, the output reader134may display a table notifying the user of acceptable (e.g., PASSED) and rejected (e.g., FAILED) substrates.

In some embodiments, the image processor124and image processing algorithm128are configured to provide two-dimensional mapping of the substrates208. In some embodiments, the image processor124and image processing algorithm128are configured to provide three-dimensional mapping of the substrates208. The two-dimensional or three-dimensional mapping data are stored in the data storage device125and may be used to reconstruct and display two-dimensional or three-dimensional figures of the substrates on the output reader134.

FIG. 3depicts a flow chart for a method300of detecting the warpage of substrates contained in substrate storage cassettes202in accordance with some embodiments of the present disclosure. The method300is described below with respect toFIG. 2. The method300may advantageously provide accurate and real-time detection of warpage of the substrates208disposed in substrate storage cassettes202.

The method300begins at302by identifying slots206having a substrate208disposed therein. Optionally, as shown at304, incorrectly slotted substrates208may be identified and subsequently corrected at306. At308, images of the exposed edges of substrates208in the slots206are captured. Optionally, in some embodiments, to improve the image quality, the edges of the substrates are illuminated with light, for example, diffusive light. At310, the captured images of the substrates308are processed. At312image analysis is performed to detect and assess the amount of warpage of the substrates. Warped substrates are rejected and satisfactory substrates are accepted. At314, the image analysis results are displayed and reported so that only the accepted substrates are processed in one or more processing chambers that may be provided in accordance with one or more embodiments of the present disclosure.

Method300may be performed on substrates disposed in substrate storage cassettes202. The method300can be performed using standalone equipment, as discussed above with respect toFIGS. 1 and 2. Alternatively, the method300can be performed at the interface of one or more cluster tools, for example, a cluster tool400described below with respect toFIG. 4. In some embodiments, the method300may be performed on substrates disposed in substrate storage cassettes202provided at the interface of a standalone process chamber.

Examples of the cluster tool400include the CENTURA® and ENDURA® integrated tools, available from Applied Materials, Inc., of Santa Clara, Calif. However, the methods described herein may be practiced using other cluster tools having suitable process chambers coupled thereto, or in other suitable process chambers. For example, in some embodiments the inventive methods discussed above may advantageously be performed in an integrated tool such that there are limited or no vacuum breaks between processing steps.

FIG. 4depicts a cluster tool suitable for performing portions of the present disclosure. Generally, the cluster tool is a modular system comprising multiple chambers (e.g., process chambers402A-D, service chambers404A-B, or the like) which perform various functions including substrate center-finding and orientation, degassing, annealing, deposition, and/or etching. According to embodiments of the present disclosure, the cluster tool may include chambers such as ion implantation chambers, etch chambers, and the like. The multiple chambers of the cluster tool are mounted to a central vacuum transfer chamber which houses a robot adapted to shuttle substrates between the chambers. The vacuum transfer chamber is typically maintained at a vacuum condition and provides an intermediate stage for shuttling substrates from one chamber to another and/or to a load lock chamber positioned at a front end of the cluster tool.

By way of illustration, a particular cluster tool400is shown in a plan view inFIG. 4. The cluster tool400generally comprises a plurality of chambers and robots and is equipped with a microprocessor controller406programmed to carry out the various processing methods performed in the cluster tool400. A front-end environment408is shown positioned in selective communication with a pair of load lock chambers (load locks410). A substrate storage cassette loader412disposed in the front-end environment408is capable of linear and rotational movement (arrows414) to shuttle cassettes of substrates between the load locks410and a plurality of substrate storage cassettes202which are mounted on the front-end environment408. The load locks410provide a first vacuum interface between the front-end environment408and a transfer chamber416(e.g., a vacuum transfer chamber). Two load locks410are provided to increase throughput by alternatively communicating with the transfer chamber416and the front-end environment408. Thus, while one load lock410communicates with the transfer chamber416, a second load lock410communicates with the front-end environment408. A robot418is centrally disposed in the transfer chamber416to transfer substrates from the load locks410to the various processing chambers402A-D and service chambers404A-B. The processing chambers402A-D may perform various processes such as physical vapor deposition, chemical vapor deposition, etching, cleaning, and the like, while the service chambers404A-B may be adapted for degassing, orientation, cool down, and the like.

For the purposes of practicing embodiments of the present disclosure, the high resolution camera102of the warpage detector100is mounted on the substrate storage cassette loader412and the DAI108is communicatively coupled to the microprocessor controller406.

Substrate warpage PASS/FAIL results send to the DAI108for storage in the data storage device125are further transmitted to the microprocessor controller406. The microprocessor controller406instructs the storage cassette loader412to select only PASSING substrates, for processing in the various processing chambers402A-D. Accordingly, resources are conserved and process quality is advantageously improved by detecting warped substrates prior to substrate processing.