The charge and behavior of flaked particles in tungsten dry etching equipment examined by using particle radar : Technologies supporting semiconductor scientific manufacturing : Process monitoring, testing, failure analysis and reliability

An in situ particle detection system (Particle Radar), which can measure the trajectory of a single flaked particle by using a laser light scattering method, is applied to tungsten etch-back equipment to study how to design particle-free equipment and the process. Reciprocating motion is used to trap particles near the anode, so that particles are not present near a wafer during etching. By shutting off the RF power, the particles trapped near the anode fly to the chamber wall, just as residual plasma potential. Next, the particles are attracted to the wafer by its residual self-bias voltage. Such a transport path of the particles suggests that they are charged positive. On the basis of this information, the bias electrodes were installed in the process chamber and a negative voltage was applied. The results show a capacity for the electrodes to attract particles.