Reducing or eliminating the presence of particle contaminants is an important step in tool qualification. While surface scanning is currently the industry standard for particle detection, bench top and hand held airborne particle counters are also used because of their relatively low cost and easy operations. However, these technologies offer limited reach inside equipment and provide little or no information about the location of contamination in the tool. Also, these traditional particle counting technologies offer no or limited real-time output or the capability to record data for future comparisons.
Addressing these issues, CyberOptics Semiconductor developed the WaferSense® Airborne Particle Sensor (APS) that can detect particles down to 0.1 Micron without opening the tool and automatically report the presence of airborne particles. With real-time views of particle conditions, process engineers can address specific trouble spots and be better prepared to prequalify tools for final particle qualifications on the very first attempt.
Below is a quick comparison of the most popular particle counting technologies available on the market today:
| Monitor Wafers & Surface Scanning | Bench Top | Hand Held | WaferSense® Airborne Particle Sensor |
Particle detection | 0.05 Micron
| 0.1 Micron
| 0.3 Micron
| 0.1 Micron and larger
|
Set up | Requires partitioning | Requires long hoses to reach into the tool | Only accessible by hand | Wafer like shape compatible to existing automation |
Follows wafer path
| Monitor wafers follow the path of the wafer but provide little information about the location of contamination in the tool | Only easily accessible by hand locations
| Only easily accessible by hand locations | Moves through equipment and automated material handling systems to monitor airborne particles inside the systems and provide real-time feedback |
Records data | No | ? | ? | Particle data can be recorded to compare past to present as well as tool to tool |
Real-time surface scanning | No | Yes but only in easily accessible areas | Yes but only in easily accessible areas | Yes |
Operations | Sometimes long delays waiting for results; Partitioning with multiple monitor wafers is often required to locate the source of particle contamination | Engineers sometimes must crawl through equipment to make measurements; measurements not possible under production conditions | Difficult to reach all places in equipment; measurements not possible under production conditions | Moves through semiconductor process equipment and automated material handling systems to monitor airborne particles inside the systems under actual production conditions (limited by same conditions) |
Software | No | No | No | Companion software collects and display particle data wirelessly to see the effect of adjustments in real time, speeding equipment qualification and setup |
For more about WaferSense Airborne Particle Sensor, please refer to http://www.cyberopticssemi.com/products/wafersense/aps.
Filed Under: Industrial automation
