This disclosure relates to a substrate handling, and more particularly to an apparatus and a method of handling a substrate.
An electronic device may result from a substrate that has undergone various processes. One of the processes may include introducing impurities or dopants to alter one or more of electrical, optical, and mechanical properties of the original substrate. For example, charged ions, as impurities or dopants, may be introduced to a substrate, such as a silicon wafer, to alter electrical properties of the substrate. One of the processes that introduces impurities to the substrate may be an ion implantation process.
Among other tools, an ion implanter is used to perform ion implantation. A block diagram of a conventional ion implanter is shown in
In operation, a substrate handling robot (not shown) disposes the substrate 114 on the platen 116 that can be moved in one or more dimensions (e.g., translate, rotate, and tilt) by an apparatus, sometimes referred to as a “roplat” (not shown). Meanwhile, ions are generated in the ion source 102 and extracted by the extraction electrodes 104. The extracted ions 10 travel in a beam-like state along the beam-line components and implanted on the substrate 114. After implanting ions is completed, the substrate handling robot may remove the substrate 114 from the platen 116 and from the ion implanter 100.
Referring to
Initially, the lift pins 208 are in a lowered position. The substrate handling robot 210 then moves a substrate to a position above the platen 116. The lift pins 208 may then be actuated to an elevated position (as shown ion
One of the deficiencies of the conventional ion implanter 100 may be found in the process of removing the substrate 114 from the platen 116. During implantation, a portion of the substrate 114 may be in contact with the edge 202 of the platen 116. As the substrate 114 is elevated, the contacted portion may remain attached to the edge 202 of the platen 116, while other portions of the substrate may be elevated. The substrate handling robot 210 attempting to retrieve the substrate 114 may collide with the partially elevated substrate 114, and the substrate 114 may either break from the collision or fall to another portion of the implanter 100.
Since these collisions may decrease the efficiency of the implanter 100, the cost of processing the substrate 114, and ultimately the cost of the manufactured semiconductor devices, may increase. As such, a new apparatus and method for removing the implanted substrate 114 from the platen 116 is needed.
The problems of the prior art are overcome by the apparatus and method of this disclosure. An apparatus having a detecting system and controller and a substrate robot is used to handle processed substrates. The detecting system, capable of determining whether a substrate is tilted, is positioned proximate to the substrate. The detecting system is adapted to measure the tilt of the substrate relative to the platen. The detecting system is in communication with a controller, which, in turn, is in communication with a substrate handling robot.
In some embodiments, the detecting system is a distance measuring system. In this embodiment, the detecting system measures the distance to the substrate after the robot has placed the substrate on the platen. It then measures the distance to the substrate after the substrate is processed. If the difference between these two distances is too great, the controller determines that the substrate is tilted.
In other embodiments, the detecting system is an angle sensor. In this embodiment, the detecting system measures the difference in direction between the transmitted wave and the wave reflected off the substrate. If this difference is too great, the controller determines that the substrate is tilted.
If the controller, based on date received from the detecting system, determines that the substrate is tilted beyond an acceptable range, it is assumed that the substrate has remained attached to the platen. In such a scenario, the substrate handling robot does not attempt to remove it from the platen. By preventing the substrate handling robot from attempting to remove the substrate, the substrate is not damaged.
In order to facilitate a fuller understanding of the present disclosure, reference is now made to the accompanying drawings, in which like elements are referenced with like numerals. These drawings should not be construed as limiting the present disclosure, but are intended to be exemplary only.
In the present disclosure, several embodiments of an apparatus and a method for handling a processed substrate are introduced. For purpose of clarity and simplicity, the present disclosure will focus on an apparatus and a method for handling a substrate that is processed by a beam-line ion implanter. Those skilled in the art, however, may recognize that the present disclosure is equally applicable to other types of processing systems including, for example, a plasma immersion ion implantation (“PIII”) system, a plasma doping (“PLAD”) system, an etching system, an optical based processing system, and a chemical vapor deposition (CVD) system. As such, the present disclosure is not to be limited in scope by the specific embodiments described herein.
Referring to
In one embodiment, the detecting system 220 is a distance measurement system, capable of determining the distance between the detecting system 220 and the substrate 114 or a specific portion of the substrate 114. In this embodiment, the detecting system 220 may preferably be an optical light based system, such as a laser based system comprising a light source and one or more light detectors, located proximate to the light source. The light source is used to illuminate the object to be measured. Once illuminated, the object reflects a portion of the light back toward the detecting system. The light detectors determine the angle of incidence of the reflected beam, using various techniques, including but not limited to cameras and focusing lenses. Based on the angle of incidence of the reflected beam, the detecting system can determine the distance to the object. Alternatively, the detecting system may utilize induction or ultrasonic waves to determine the distance to the object. The system may also be an electromagnetic wave based system.
Time of Flight systems determine the distance to an object based on the time required for light to travel to the object and back to the detecting system. In some embodiments, a periodic waveform, such as a sinusoidal wave is emitted from a laser. The phase difference between the emitted wave and reflected wave is used to determine the distance from the detecting system to the object. Other techniques capable of measuring the distance to an object are also within the scope of the disclosure.
The detecting system 220 may be configured to observe at least a portion of the substrate. Preferably, the observed portion may be near the center of the substrate 114 or near an outer edge of the substrate 114. However, it is also within the scope of the present disclosure that the detecting system may be configured to observe other portions of the substrate. Furthermore, the detecting system 220 may also be configured to observe, for example, platen or lift pins. In other embodiments, a plurality of detecting systems 220 is utilized to observe a plurality of locations. For example, detecting systems 220 may be used to measure a plurality of locations along the outer edge of the substrate 114. In this way, the detecting systems are able to reliably ascertain substrate adhesion issues.
Hereinafter, operation of the distance based method for determining the orientation of the substrate 114 will be described. Initially, the substrate 114 is received by the lift pins 208, as shown in
Prior to being retrieved, however, the distance between the same portion of the substrate 114 and the detecting system 220 is measured for the second time (the “second distance”). Thereafter, the first and second distances are compared by the controller 230. If the difference of the first and second distances is unacceptably high (e.g. 1-10 mm), a determination can be made that at least a portion of the substrate 114 is attached to the platen 116 and the substrate 114 is oriented in an excessively tilted state. Thus, the controller 230 compares the difference between the first and second distances to an acceptable range. For example, the controller 230 may be configured such that the difference between the two distances must be in the range between −1 and +1 mm. If such a determination is made, the substrate handling robot 210 may be prevented from retrieving the substrate 114. Otherwise, the robot 210 may retrieve the substrate 114.
Alternatively, the detecting system 210 may be capable of determining the orientation of the object based on angle of the orientation. Preferably, a triangular based detecting system is used in this mode. As described above, the detecting system 220 is preferably an optical light based system. However, those of the art will recognize that the detecting system 220 may also be other types of systems capable of determining the orientation of the substrate. Although the disclosure refers to a light beam being used, those skilled in the art will recognize that any suitable emitted wave (such as ultrasonic, electromagnetic, of light) can be utilized. Processed wafers are generally highly optically reflective, similar to a mirror. This property is conductive to implementing an angle sensor.
Hereinafter, operation of the angle based method for determining orientation of the substrate 114 will be described. Initially, the substrate 114 is received by the lift pins 208 of the platen 116, as shown
Prior to being retrieved, an electromagnetic wave, such as an optical beam, from the detecting system 220 may be directed to the substrate. In many cases, the substrate surface 114 may be highly reflective to the optical beam.
An advantage of the angle based method may be that the method may compensate the detecting system 220 having difficulty in accurately measuring distance between the substrate 114 and the detecting system 220. Such a difficulty may arise due to the highly reflective nature of the substrate surface. In the present disclosure, the angle based method may preferably be implemented with a “line” beam rather than a spot beam, as the line beam may accurately determine the tilt state even if angular variation is in one direction.
In the present disclosure, the detecting system 220 may be oriented such that the line beam has a parallel relationship with any two lift pins. Such an orientation may allow the determination of the substrate's tilt about a line between the two lift pins.
In another embodiment, a camera, such as a CCD camera is positioned next to the platen. When the substrate is lifted by the lift pins, the camera is used to capture an image of the substrate configuration. If the image shows that the substrate is flat, and at the proper elevation relative to the platen, the substrate-handling robot is used to remove the substrate. However, if the substrate is tilted, or if the elevation relative to the platen is not within an acceptable range, the robot is prohibited from removing the substrate.
Thus, the detecting system 220 is adapted to detect a parameter related to the orientation of the substrate. In some embodiments, this parameter is the distance from the detecting system 220 to the substrate 114. In other embodiments, this parameter is the angle of substrate 114 relative to a fixed surface, such as the platen 116. Furthermore, as described above, in certain embodiments, multiple detecting systems are utilized to detect these parameters for a plurality of portions of the substrate.
Although embodiments described herein are directed to a specific apparatus and method for detecting the substrate orientation and for handling the substrate processed by ion implanter, the present disclosure may be applicable to other processing system such as, for example, PIII system, PLAD system, laser processing system. As such, the present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Further, although the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes.
This application claims priority of U.S. Provisional Patent Application Ser. No. 61/025,142, filed Jan. 31, 2008, the disclosure of which is hereby incorporated by reference.
Number | Date | Country | |
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61025142 | Jan 2008 | US |