The performance of semiconductors sets the pace for innovation. This is true for industrial automation as well as for communication via cell phones, laptops and the like, for smart building technology and for the automotive industry. And the market continues to grow. In 2018, the international semiconductor industry achieved a turnover of 481 billion US dollars; according to a study by PwC, this figure is expected to reach 525 billion US dollars by 2022.

The robotics industry is also benefiting from this development, for example because the latest generations of control systems and controllers offer additional functions. Conversely, the innovative strength of robot manufacturers is also accelerating the efficiency and productivity of microprocessor manufacturers.

One example: Kuka offers a wide range of extremely flexible robots that can be quickly adapted to a variety of handling requirements - after all, the life cycle of semiconductors is short and the market is correspondingly volatile.

Mobile handling system for the cleanroom

Individual production steps can be automated very well and to a high level of quality in this way. The transportation of semiconductor substrates (wafers) from one workstation to the next has been an exception to this rule. Complete automation is required here because the clean room conditions are much easier to guarantee in 'unmanned production'. Until now, however, this has been hampered by the lack of precision with which mobile robots move and grip.

Now Kuka has developed what it claims is the world's first solution from a single source that can automatically transport and handle semiconductor cassettes: the 'Semi Mobility Solution'. For this purpose, a lightweight robot from the 'LBR iiwa' series is mounted on an autonomous automated guided vehicle (AGV) of the type 'KMR 200 CR'. The AGV can maneuver in the tightest of spaces - and a special gripper system has been developed for handling it.

With mobile robots, the gripping process itself is guided by image processing.

© Kuka

The 'Semi Mobility Solution' travels to a transfer point where there are transport boxes for wafers. Once the AGV has reached its destination, the robot arm is able to determine its exact position and perform a fine calibration with the help of an integrated image processing sensor. This enables the robot to grip the transport box with a high degree of accuracy and place the sensitive wafers in a tray on the AGV platform without causing any vibrations. Boxes in two sizes for wafers with a diameter of 200 or 300 mm can be handled and transported. Once it reaches its destination, the robot places the transport boxes on the respective processing system.
In the room, the 'Semi Mobility Solution' moves on the basis of stored destinations, but chooses the route there itself. This is made possible by the navigation capability of the 'LBR iiwa' platform, which is sensitive and safe when traveling autonomously. Laser scanners support environment tracking by perceiving the surroundings in real time and thus avoiding collisions.

The safety-oriented environment detection also creates the conditions for the platform to be used as a cobot without a safety fence, in the immediate vicinity of the operating personnel. The gripping process itself is guided by image processing.

Image processing sensor guides the gripping process

When selecting the image processing system, the Kuka developers opted for 'In-Sight 2000' sensors from Cognex. These sensors combine the performance of image processing systems with the simplicity and low cost of an industrial sensor. They also offer a high degree of flexibility for installation in the smallest of spaces - a key feature, as the image processing sensor travels on the robot arm. The minimized cabling effort of the sensor - thanks to its integration via Ethernet and PoE - is another reason for the decision. In addition, the logic of the 'In-Sight 2000' is integrated into the device and image processing can be 'taught' very easily.

An In-Sight 2000 image processing system from Cognex takes care of referencing and positioning the gripper with millimeter precision. An integrated LED ring light ensures uniform illumination even in changing ambient conditions.

© Cognex

The integrated LED ring light of the vision sensor ensures uniform illumination across the entire image, regardless of the current lighting situation. This is particularly important for mobile applications, as the lighting is not the same everywhere and the quality of the image is also affected by the time of day and season.

In practical operation of the 'Semi Mobility Solution', the robot gripper first approaches the transport box. Image processing is then activated: it detects the offset to the target point stored in the control system and uses this to reference the position of the gripper, which can then grip the respective transport box with the required precision in the millimetre range. An integrated calibration function ensures permanently precise positioning.

Kuka has already delivered the first 'Semi Mobility Solutions' to international semiconductor manufacturers. The mobile robots work under cleanroom conditions and are certified to ISO Class 3 (IPA), UL 1740 and UL 1998. They can also be used in a fleet network.

Visit Cognex at the world & conference, the virtual trade fair of Computer&AUTOMATION, starting October 5. Register here free of charge.