## 4 Results and Discussion
### Particle Sources Verified through Chamber By-Product Deposition Analysis  
Figure 5a presents the chamber by-products deposited around the ESC and edge ring after 225 h in the RF chamber. The deposited chamber by-products were analyzed through scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), as displayed in Figure 5b. Surface deposition areas from 6 to 30 \(\upmu\)m could be detected through SEM. The EDX spectra were used to analyze the percentage concentration of each element in the deposition. In Figure 5, the \(y\)-axis indicates the number of X-rays, and the \(x\)-axis indicates the energy of the X-rays. The EDX spectra contained yellow peaks corresponding to all the elements in the deposited by-products. The positions of the peaks revealed that fluorine, aluminum, and oxygen were present in the deposited by-products, and the peak heights were used to determine the concentration of each element. The composition of the deposited by-products was similar to the edge particle composition. We determined that the particles originated from the deposition occurring at the ESC side wall and edge ring.  
Figure 4: Experimental process flow for powder spray positioning and process control factor design. (**a**) Powder collection from deposition by-products inside the turbopump exhaust line. (**b**) Experimental process flow for the spraying of powder separately on the (1) top electrode, (2) edge ring, (3) chamber wall, (4) exhaust plate. Wafer process check flow was performed under wafer transfer only, N2 flow rate of 200 sccm, Top RF power 500 W, and ESC voltage of 2500 V. (**c**) Verification of the process parameters affecting the experimental flow in the chamber for more than 200 RF hours.  
Figure 5: \(Cont.\)Particle Results for Each Wafer Test Condition in Which Powder Was Placed on the Surface of Each Part in the Chamber  
Figure 6 reveals that numerous wafer particles were formed under the wafer transfer only, an N\({}_{2}\) gas flow rate of 200 sccm, a maximum RF power of 500 W, and an ESC voltage of 2500 V when powder was sprayed on the top electrode's surface. Particles were suspended and fell onto the wafer because of the turbulence of the flow field caused by the gas, or the electric field generated by the RF plasma and ESC. For powder sprayed on the surface of any part in the chamber, the number of wafer particles produced when the ESC voltage was 2500 V was higher than that produced under any other condition. The particle and edge maps revealed a random particle distribution when the ESC voltage was 2500 V. The ESC voltage appeared to affect the movement of particles to the wafer surface. As presented in Figure 7, the maximum particle count on the wafer was 1205 when the ESC voltage was 2500 V.  
Figure 5: Chamber deposition position analysis for the ESC and edge ring. (**a**) By-product deposition positions around the (1) ESC side wall and related parts, (2) inner side of the edge ring, and (3) surface of the edge ring. (**b**) SEM images and EDX spectra for the deposited by-products. The most common elements in the deposited by-products were fluorine, aluminum, and oxygen. The composition of these by-products was similar to that of the edge particles.  
Figure 6: Wafer particle counts when powder was spread over the surfaces of four chamber parts.