Airborne Particle Sensor Monitors Slit Valves Without Chamber Cool Down in High Density Plasma (CVD) Tool

Semiconductor manufacturing processes require a contamination-free environment for process optimization and optimum yield.  Particles measuring just nanometers within process chambers can cause yield-reducing defects.

One highly sensitive area within semiconductor process equipment are slit valves through which in-process substrates squeeze through when transferred between process chambers.  During wafer contact, these slit valves can shed diffused particles that can slip in and out of the chambers, potentially causing wafer defects. 

Particle monitoring of slit valves can be challenging as some process chambers cannot be cooled down to 45°C  since the chamber wall is fixed at 50°C and cooling could cause particle generation. 

By using inert gases of N2 or argon, the WaferSense® Airborne Particle Sensorcan check slit valves without entering or cooling down process chambers, offering a faster monitoring method.  Shaped like a wafer and measuring just 8.5 mm tall, the Airborne Particle Sensor (APS) moves through semiconductor process equipment to monitor particle sources in toolas wafers are transferred and slit valves actuate.

 APS Monitors Slit Valve Contamination in High Density Plasma Tool

When used to monitor slit valves within the process chambers of a High Density Plasma (CVD) Tool, the APS wastransferred in front of the slit valve of a high temperature chamber by the blade of a buffer robot.  The air pressures of a buffer and HDP chamber were balanced while the HDP chamber temperature remained above 45°C.

Capable of detecting and counting particles as small as 100 nm, (0.1 micron), the APS providedreal-time views of particle conditions to address areas of concern instead of the whole tool to determine when and where contamination occurred.  During monitoring, the APS determined that the slit valve motions of Chamber A had many particles (as shown in graphic A) while other slit valves of chambers B, D and D did not.  By identifying the source of specific chamber shedding particles, engineers can take immediate corrective action, in this case replacing worn slit valves.

Through Bluetooth technology, the APS communicated particle data wirelessly to a dedicated Link Box that interfaces with the sensor’s companion application software that runs on a laptop or system console.  Here, the particle size and count information was processed, displayed and stored.With this information, engineers efficiently classified particles and their exact sources.

Because the APS application software replays log file data, engineers can review and analyze past to present operations as well as one chamber to another to conduct data comparisons among chambers and tools.