Method for Ultra Rapid Determination of the Lubrication Mechanism in Chemical Mechanical Planarization

Abstract

In chemical mechanical planarization (CMP), Stribeck curves are normally constructed by plotting average coefficient of frictions (COF) against the average Sommerfeld number. Consequently, traditional Stribeck curves fail to provide a full explanation of the lubrication phenomena simply because COF and polishing downforce can fluctuate significantly due to stick-slip phenomena and transient instabilities caused by polishing kinematics and consumables. This study introduces a new method for rapidly generating an "improved" Stribeck curve (i.e. Stribeck+ curve) that shows a more complete tribological picture of the process. The method significantly reduces the consumables and time required to obtain the curve compared to traditional means. Results of the Stribeck+ curve are consistent with individual tests using several different consumables combinations. All copper CMP Stribeck+ examples clearly indicate the lubrication mechanism and transitions thereof between different polishing conditions. Variability in COF as well as a much wider range in v/P are also explored.

Investigation of the Impact of Pad Surface Texture from Different Pad Conditioners on the CMP Performance

“…Stribeck curves are deployed to further understand the tribological mechanism of solid and porous pads conditioned with coarse and fine pad conditioning disk, as carried out by previous researchers. [49][50][51][52] There are three major types of contact depicted in Fig. 14 based on Ludema's definition.…”

“…Also, where "μ" is the viscosity of the slurry, "V" is the relative sliding velocity of the pad-wafer, P is the wafer pressure and "δ eff " is the effective film thickness. The work done by the group of Philipossian et al [49][50][51][52] explained that Stribeck curves are useful in understanding the tribological mechanisms involved during a CMP process.…”

Effect of Conditioning and Slurry Application Method on Silicon Dioxide Removal Rates Using a Ceria-Based Chemical Mechanical Planarization Slurry

“…Stribeck+ curves 27 for the in-situ and the ex-situ conditioning cases are shown in Figure 4 which help one gain a deeper understanding of the fluctuations and clusters seen in Figures 2 and 3. Different from traditional Stribeck curves (i.e.…”

Characterization of Cosmetic Dispersions Based on Friction Dynamics

“…This suggests that the viscosity of cosmetics was one of the dominant factors. In the Stribeck curve, a classical model for friction phenomena, the contact state between solid surfaces can be described using the Sommerfeld number S 21) , S＝η V/W (7) where η and W are the viscosity of the fluid and vertical force between solids. When S is sufficiently large, two solid surfaces are in a fluid-lubricated state where they are completely separated by a continuous liquid film.…”