Numerous flaked particles instantaneously generated by micro-arc discharge in mass-production plasma etching equipment

Abstract

The relationship between the instantaneous generation of flaked particles and micro-arc discharge is investigated in mass-production plasma etching equipment. To investigate the mechanism of such particle generation, we simultaneously detect particle generation from deposited films on a ground electrode and occurrence of micro-arc discharge under mass-production conditions. The results indicate that the deposited films are severely damaged and flake off as numerous particles when micro-arc discharge occurs. The rapid changes in floating potential on the films due to micro-arc discharge cause electric field stress, which works as an impulsive force. The particles are generated not from the melting of chamber parts by micro-arc discharge but from the flaking of deposited films by electric field stress acting as an impulsive force.

Increase in Size of Flaked Particles Suddenly Generated by Impulsive Force in Mass-production Plasma Etching Equipment

“…As the arcing is extinguished and the rf power returns, the probe signal then returns to the initial value before the arcing. As a consequence, these results indicate that the inner wall potential changing rapidly causes the electricˆeld stress which can work as impulsive force and many ‰aked particles [11][12][13][14] .…”

“…During plasma etching process, the etching reaction products adhere to the inner walls of the process chamber, and gradually deposit asˆlms as many wafers are processed. The particles are generated by ‰aking of the depositedˆlms caused by electricˆeld stress that acts at the boundary between the insulating inner wall and thê lm 6,[11][12][13][14][15] . The electricˆeld is formed between the inner wall surface at the ‰oating potential (inner wall potential) and the chamber at the ground potential.…”

“…In addition, a lot of particles sometimes suddenly ‰ake oŠ and give rise to many defective LSI devices. We have previously elucidated the mechanism that the number of particles instantaneously increases when the electricˆeld stress acts as impulsive force [11][12][13][14] . An impulsive force is known in classical mechanics as a force becoming much larger as the time to act becomes much shorter 16,17) .…”

“…We have also clariˆed that the depositedˆlm can largely deform and ‰ake oŠ as many particles owing to the impulsive force of electricˆled stress, from the calculated result using the forced oscillation model 12) . In addition, we have elucidated that micro-arc discharge is a cause of the sudden generation of many ‰aked particles 13) . The existence of the phenomenon of the impulsive force of electriĉ eld stress has been conˆrmed by using the standard particles 14) .…”

Monitoring of Condition of Deposited Film Causing Particles in Plasma Etching by Using Practical Load Impedance Monitoring Method

“…After that, the etching reaction products are attached and gradually deposited on the inner walls as more wafers are processed, and the products formˆlms. Particles are generated from theˆlms due to electricˆeld stress, which acts at the boundary between the insulating inner wall and thê lm during plasma processing and causes theˆlm to ‰ake oŠ 6,[11][12][13][14] . The electricˆeld is formed between the inner wall surface at a ‰oating potential and the chamber at a ground potential.…”