| AVS 62nd International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | Yuji Kasashima, National Institute of Advanced Industrial Science and Technology (AIST), Japan |
| Correspondent: | Click to Email |
The mechanism of instantaneous generation of many flaked particles is investigated in mass-production plasma etching equipment. The results indicate that the deposited films are severely damaged and flaked off as many particles when an inner wall potential (floating potential) changes instantaneously and the electric field stress works as an impulsive force.
Particle contamination in plasma etching equipment significantly lowers production yield and overall equipment efficiency. In plasma etching, etching reaction products adhere to the inner chamber walls, gradually forming films as wafers are processed. Particles are generated by flaking of the deposited films due to electric field stress. In mass-production line, serious contamination caused by many particles sometimes suddenly occurs.
The experimental apparatus is the mass-production reactive ion etching equipment which can generate capacitively coupled plasma discharge. The etching process sequence and equipment parameters are similar to those used in actual manufacturing facilities. This study uses a titanium etching process that often causes significant particle contamination in mass-production equipment.
Flaked particles are detected by the in situ particle monitoring system. A sheet-shaped laser beam is introduced in a plane parallel to the wafer in the processing chamber at a distance of 4 mm from the ground electrode. The light scattered by particles is measured using an image-intensified charge-coupled device camera. The viewing port style plasma probe (VP-Probe) can detect a transient change in the floating potential formed on the inner surface of the chamber.
In this experiment, electrostatic chuck voltage much higher than usual is supplied to induce micro-arc discharge at the back of wafer. Many particles are detected simultaneously with the abrupt increase in the amplitude of VP-Probe caused by the micro-arc discharge. The arcing at backside of the wafer and many particles from the ground electrode occur simultaneously. That is, these phenomena occur at the same time despite in different parts of the chamber. The large and rapid change in the inner wall potential due to the arcing can make the electric field stress acting on the deposited film work as an impulsive force, generating numerous flaked particles suddenly.
Accordingly, the results reveal that the floating potential on the inner chamber wall changing rapidly and markedly causes many flaked particles because the deposited films are strongly damaged by the impulsive force of electric field stress. This mechanism can occur on not only a ground electrode but also a chamber walls, and lead to serious contamination.