WaferSense™ Auto Teaching System (ATS) FAQ
CyberOptics Semiconductor provides answers to the most commonly asked questions about WaferSense ATS.
We are constantly adding questions and answers to our product FAQ section. If you don't find your product question/answer, please contact us.
Principles of Operation
- How is teaching achieved by the ATS teaching wafer?
- What is a target?
- Why do I need a target inside my equipment?
- What is a good target?
- What advantages does ATS provide over existing teaching methodologies?
Product Uses and Features
- What ATS form factors are available?
- What materials are used in the construction of ATS teaching wafers?
- How do I receive offset measurements from my ATS teaching wafer?
- What is the ATS working distance range?
- Can I use my ATS wafer for teaching robot arms?
- Can I use my ATS wafer to teach wafer transfers inside my equipment?
- Can I use my ATS wafer to teach the z coordinate for a robot move?
- Can I use the ATS teaching wafer at elevated temperatures?
- Can I use the ATS teaching wafer at low pressures (vacuum)?
- How do I charge the ATS teaching wafer?
Maintenance and Repairs
- How can I check that my wafer is providing correct offset data?
- What is offered as part of the ATS calibration service?
TeachView™ and Software
Interference, Contamination and Safety
- How does the ATS communicate with the TeachView application?
- How do I safely handle the ATS teaching wafer?
- Will my ATS teaching wafer outgas when subjected to high temperatures?
- Will my ATS teaching wafer contribute to particulate contamination?
- How do I maintain the cleanliness of the ATS teaching wafer?
Principles of Operation
How is teaching achieved by the ATS wafer?
Ideally wafers sit centered inside semiconductor equipment stations and robot end effectors. The ATS teaching wafer emulates a silicon wafer and measures the distance between its center and visible features of the equipment stations and/or end effectors.
The downward looking camera inside the ATS first acquires images of the station. ATS then uses pattern recognition software to detect and locate circular features, called targets. Finally ATS uses onboard calibration data to calculate the x, y, and z offsets from the ATS sensor wafer’s geometric center to the target’s center. The offsets are displayed via the TeachView software both numerically and graphically. A technician can adjust the automation system so that wafers are accurately and reproducibly centered at each station.
What is a target?
Targets are visible circular features of a semiconductor equipment station. For example, a target may be a support pin, a vent hole or an alignment hole. Targets are permanent and do not change size, appearance or location over time.
Why do I need a target inside my equipment?
Pattern recognition software used by the ATS sensor wafer “expects” to encounter targets as part of the image data collected by the on-board camera. Targets are essential to determining where a certain equipment station is in relation to the ATS sensor wafer. When the target is located at the center of an equipment station, the technician can conveniently move the robot until the x-y offset is close enough to zero. If your targets are not centrally located, you can still teach your equipment using ATS. Please contact technical support for additional information.
What is a good target feature?
ATS is designed to find circular targets as most targets on equipment stations are circular. Circular targets look the same regardless of the orientation or the ATS. Circular targets can be accurately found even when only a portion of the target is present in the image. The optimum target diameter depends on the distance from the bottom of the ATS sensor. Target diameters typically range in size from 3 mm to 10 mm.
Back to the Top
What advantages does ATS provide over existing teaching methodologies?
Legacy teaching methodologies include mechanical jigs that use dowel pins and wired “camera-on-wafer” systems. Legacy methods require the equipment be cooled down and partially dismantled. These methods have many drawbacks, such as wires that break, time-consuming setup and lack of digital output.
Wafer-like and wireless, the ATS eliminates the need to interrupt equipment from its production-ready state, thus significantly reducing the time it takes to verify correct teaching or make adjustments. Additionally it provides offset data that can improve your process reproducibility and yield.
Product Uses and Features
What ATS form factors are available?
The WaferSense ATS teaching wafers are available in two sizes: 200 mm (8") and 300 mm (12").
What materials are used in the construction of ATS teaching wafers?
The ATS teaching wafers are made of carbon fiber substrate that is coated with an epoxy film. The top of the wafer is covered with a polycarbonate label.
How do I receive offset measurements from my ATS teaching wafer?
Offset data is transmitted to a computer via the wireless link connected to a USB port. Each ATS wafer is paired and will communicate with a wireless link via the Bluetooth communication protocol. This protocol employs radio frequency energy in a frequency band centered around 2.4 GHz.
What is the ATS working distance range?
ATS measures offsets to targets 6.5 mm – 45 mm below the teaching wafer.
Can I use my ATS wafer for teaching robot arms?
Yes. The wafer-like form factor and edge profile allow the ATS device to be handled as a wafer by a variety of robot arms.
Can I use my ATS wafer to teach wafer transfers inside my equipment?
Yes. The wafer-like form factor allows the ATS device to be picked up from a carrier with a robot arm, placed on an aligning station, and then circulated inside the semiconductor equipment as a wafer. Most load locks, slit valves and process chambers easily accommodate the ATS teaching wafer. ATS provides the objective feedback technicians need to verify or adjust wafer transfer robot coordinates.
Can I use my ATS wafer to teach the z coordinate for a robot move?
Yes. The ATS reports x, y and z offsets. When a robot end effector holds the ATS teaching wafer above a target the reported z offset represents the distance from the ATS wafer to the target plane. When resting on elevated pins, the reported z offset represents the distance from the ATS wafer to the pedestal/plate. Measurement accuracy: ±0.1 mm (±0.004") for x-y and ±0.5 mm (±0.02") for z.
Can I use the ATS teaching wafer at elevated temperatures?
Yes. The ATS wafer provides the most accurate offset measurements when its internal temperature is between 20°C and 50°C. However, the ATS sensor wafer will operate safely for short periods of time (typically less than five minutes) when exposed to air at temperatures of up to 120°C. (ATS sensor wafers should not be placed on surfaces whose temperature exceeds 75°C.) Exposing ATS to environments which cause its internal temperature to exceed 80°C will irreversibly damage the electronics within the device enclosure.
Can I use the ATS teaching wafer at low pressures (vacuum)?
Yes. The ATS teaching wafer can be safely used under pressures ranging from atmospheric to ultra-high vacuum.
How do I charge the ATS teaching wafer?
A specially adapted individual wafer carrier is provided with each ATS wafer to protect it in transit and to aid in charging the battery. Simply return the wafer to its carrier then connect it to an electrical outlet via the charging adaptor provided. Although the battery takes a total of two hours to fully charge, 80% of the charge will be available within the first hour.
Maintenance and Repairs
How can I check that my ATS teaching wafer is providing correct offset data?
Your teaching wafer provides accurate offset data for at least 12 months from factory calibration. Your wafer's last calibration date is imprinted on a label affixed to the top of the electronics enclosure. Also accessing the “About your ATS Wafer" option under the "Help" menu while TeachView software is running will provide you this information. ATS, like any measuring instrument, should be checked regularly to verify that its measurements are accurate. If more than 12 months have passed since your sensor was last calibrated, we recommend you contact technical support to make arrangements to return your ATS device for factory calibration verification.
What is offered as part of the ATS calibration service?
CyberOptics Semiconductor is the only facility authorized to perform verification of ATS calibration, replacement of ATS batteries, and repairs for product and parts. The calibration service offered for ATS includes replacing the batteries, verifying measurement accuracy, and issuing calibration certificates to users. When appropriate, recommendations are made for remedial actions for teaching wafers that do not perform as specified.
TeachView™ and Software
How do I log offset data I measure with the ATS teaching wafer?
The TeachView software (provided with ATS) offers users an easy way to log offsets (x, y and z) associated with a wafer location. The prominent “Log a Reading” button may be pressed at any time to log the offsets displayed.
What can I do with logged data?
Data logged with TeachView can be retrieved from the default CSV (comma-separated values) file. Microsoft Excel (and other applications that can import CSV files) can be used to display the data in a table or graph format. You may then employ statistical processing tools (i.e., trend analysis, statistical process control, etc.) to characterize your equipment’s behaviors and improve yield.
Interference, Contamination and Safety
How does ATS communicate with the TeachView application?
The ATS wafer employs Bluetooth communication technology to relay offset data to a PC via the link box. Bluetooth communications use the 2.4 GHz frequency band.
How do I safely handle the ATS teaching wafer?
The ATS teaching wafer is much more durable than a silicon wafer. It is a sensitive electronic measurement instrument that should be handled gently. For example, please avoid impact with hard objects, especially those that could scratch the lens or break the illuminator on the wafer’s bottom surface.
Will my ATS teaching wafer outgas when subjected to high temperatures?
No. Please contact technical support to request a copy of our outgas test report.
Will my ATS teaching wafer contribute to particulate contamination?
No. Please contact technical support to request a copy of our particulate test report.
How do I maintain the cleanliness of the ATS teaching wafer?
CyberOptics Semiconductor cleans each component of the ATS to semiconductor industry standards prior to assembling each ATS in a clean environment. To maintain this level of cleanliness, we recommend wiping the exterior of the device and the interior and exterior of the charging case with semiconductor-grade isopropyl alcohol.