Automating cleanroom wafer processing


ntil recently, robotics have been used in individual production steps. To

assist with transporting the highly sensitive wafers from station to station in semiconductor manufacturing, Kuka has created a mobile robot. On board the robot is an image processing system from Cognex that is high-performing, yet compact in size. KUKA offers a wide range of extremely

flexible robots that can also be quickly tailored to a whole variety of handling requirements, as the life cycle of semiconductors is short and the market correspondingly volatile. Using robotics, individual production

steps can be automated to a high standard. However, up until now, robotics have not been used to transport semiconductor substrates (wafers) from one workstation to the next. Ideally, semiconductor manufacturers would prefer end-to-end automation, to maintain cleanroom conditions, which can be much better achieved with “unmanned production.” Until now, however, this aspect of the process was untenable due to the lack of precision with which mobile robots move and grasp. KUKA has now developed a world first

single-source solution for the automated transport and handling of semiconductor cassettes: the “Semi Mobility Solution.” In this instance, a lightweight robot from the LBR iiwa series is mounted on a KMR 200 CR autonomous automated guided vehicle (AGV). The AGV can manoeuvre in the smallest of spaces and KUKA's engineers have developed a sophisticated gripper system for the handling.


SYSTEM SOLUTION: AGV PLUS ROBOT ARM PLUS GRIPPER The Semi Mobility Solution goes to a handover point where wafer transport boxes are located. When the AGV has reached its destination, the robot arm is in place to precisely determine its position with the help of an integrated image processing sensor and performs a fine calibration. This moves the robot into the position

to grasp the transport box with a high degree of accuracy and deposit the sensitive wafers without any vibrations in a storage space on the AGV platform. Using this approach, the robot can pick up and transport two different sizes of boxes for wafers with a diameter of 200 or 300mm. Once it has reached its destination, the

robot puts down the transport boxes on the respective processing line. The Semi Mobility Solution moves

around the room on the basis of stored destinations but chooses the route there itself. The navigational capacity of the LBR iiwa platform enables it to move autonomously in a safe and sensitive way. Environment tracking is supported by laser scanners. They perceive the environment in real time, thus preventing collisions. The gripping process itself is guided by image processing The safety-oriented environment

Figure 1:

Cognex In-Sight 2000 image processing is responsible for the referencing and millimetre-accurate

positioning of the gripper

Kuka mobile robot revolutionises semiconductor manufacturing process, using image processing, for transporting highly sensitive wafers, with support from Cognex

recognition also creates the preconditions for being able to use the platform as a cobot (collaborative robot) without a safety fence near the operators. The gripping process itself is guided by image processing. Extremely high precision and reliability are essential in this process, because the wafers are sensitive. Vibrations must be avoided. When selecting the image processing

system to guide the robot, KUKA's developers chose Cognex’s In-Sight 2000 sensors. These sensors combine the performance of image processing systems with the ease and low cost of an industrial sensor. They also offer maximum flexibility when mounting in space-constrained environments. This attribute was highly desired in this application because the IP sensor is located on the robot arm. Minimising wiring requirements was also a key criterion and the In-Sight 2000 provided easy integration via Ethernet and PoE connections, which was another factor behind the decision. The In-Sight 2000's integrated LED

lighting provides uniform illumination over the whole image, regardless of the prevailing lighting conditions. This is particularly important in mobile applications because there is not the same lighting everywhere and even the time of day or the season can affect the image quality. In practice: IP-controlled fine

When selecting the image processing system to guide the robot, KUKA's

developers chose Cognex’s In-Sight 2000 sensors. These sensors combine the

performance of image processing systems with the ease and low cost of an industrial sensor.”

positioning over the last few centimeters. The Semi Mobility Solution first drives the robot gripper up to the transport box. At this point, the image processing is activated. It recognises the offset from the destination point stored in the control system and on this basis references the position of the gripper, which can subsequently grasp the respective transport box with the required high degree of millimetric precision. An integrated calibration function guarantees consistently accurate positioning.



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