Physical and Chemical Characterization of Reused Oxide Chemical Mechanical Planarization Slurry

Abstract

The recycle of Chemical Mechanical Planarization (CMP) slurries has been actively considered in the industry to reduce the cost-of-consumables (COC) because of the sharp increase of the consumption of slurry in CMP. The main purpose of this study was to characterize the used oxide slurry physically and chemically to establish a means of reprocessing it. The characteristics of slurry were determined according to pH, solid content, specific gravity and particle size. These characteristics were affected and varied by deionized water inflow during the CMP process. The tetraethylorthosilicate removal rate was strongly dependent on the solid content and pH of slurry solutions. The solid content played a major role in determining the removal rates. Regardless of the number of polishings, the removal rate was almost the same at a solid content when it was modified by adding new slurry. The mean particle size of slurries did not change at all even in the five times recycled slurry. Even though there was a slight increase in the fraction of large particles in the range of 20 to 120 µm in the recycled slurries, no changes in thickness uniformity or defect density were observed when polishing was performed in either new or recycled slurry.

Effect of Slurry Flow Rate on Pad Life during Interlayer Dielectric CMP

“…For instance, a threefold increase in slurry flow rate coupled with a comparable increase in pad life can reduce overall cost of ownership of the CMP module by as much as 45% if 50% of the slurry is reused. Several researchers have been able to successfully demonstrate the feasibility of ILD slurry reuse [8][9][10] and in a matter of a few years, slurry recycling is expected to become mainstream in high-volume manufacturing. The choice of system tribology is another critical consideration in process development.…”

Generation of Pad Debris during Oxide CMP Process and Its Role in Scratch Formation

“…The absence of large abnormal sized particles in the polishing residue, which were observed in Fig. 20 It should be noted that the method of gathering slurry also played a decisive role resulting in these discrepancies in delivering the different results for particle size after the CMP process. Of course, some pad debris of 0.2 lm might be present, but this possibility is unlikely since the pad would be fully covered by the slurry and wafer residues.…”

“…11,[16][17][18][19][20][21]31 In all these cases, slurry was collected only after the CMP process, and the characterization was performed with the bulk slurries. 11,[16][17][18][19][20][21]31 In all these cases, slurry was collected only after the CMP process, and the characterization was performed with the bulk slurries.…”

“…[13][14][15] Several studies have been performed in analyzing the polishing residue after polishing. 16,18,20,21 Han et al studied the effect of polishing by products on copper CMP behavior. 17 Other researchers have studied the use of polishing residue to reuse the slurry in the CMP process by analyzing the variation in particle size after polishing.…”

Effect of Slurry Injection Position on Slurry Mixing, Friction, Removal Rate, and Temperature in Copper CMP

“…The recovery and reuse of spent oxide CMP slurry has been previously investigated. 3,4 For copper, it is more difficult to reclaim spent slurry due to the nature of the chemical constituents and the presence of complex reaction products. Therefore, optimizing CMP slurry process parameters to reduce slurry usage is the best solution to achieve a more cost effective and environmentally benign process.…”