Yubo Jiao

Tribological, thermal, and kinetic characterization of 300-mm copper chemical mechanical planarization process

In this study, the tribological, thermal, and kinetic attributes of 300-mm copper chemical mechanical planarization were characterized for two different pads. The coefficient of friction (COF) ranged from 0.39 to 0.59 for the D100 pad, indicating that boundary lubrication was the dominant tribological mechanism. In comparison, COF decreased sharply from 0.55 to 0.03 for the IC1000 pad, indicating that the tribological mechanism transitioned rapidly from boundary lubrication to partial lubrication. Consequently, the D100 pad exhibited higher pad temperatures and removal rates than the IC1000 pad. A two-step modified Langmuir–Hinshelwood model was used to simulate copper removal rates as well as chemical and mechanical rate constants. The simulated copper removal rates agreed very well with experimental data and the model successfully captured the non-Prestonian behavior. The simulated chemical rate to mechanical rate constant ratios indicated that the IC1000 pad generally produced a more mechanically controlled removal mechanism than the D100 pad.

Analysis of A Novel Slurry Injection System in Chemical Mechanical Planarization

Slurry mean residence time (MRT), removal rate, and polishing defects were analyzed for a novel slurry injection system used in chemical mechanical planarization. The novel slurry injection system was placed adjacent to the wafer on the pad surface and slurry was injected towards the wafer through multiple holes in the trailing edge of the injector bottom. Results showed the novel slurry injection system provided more efficient slurry delivery to the pad–wafer interface and generated lower slurry MRT, higher removal rate, and lower polishing defects than the standard pad center area slurry application method currently used in the IC manufacturing industry.

Effect of temperature in titanium chemical mechanical planarization

The effect of temperature on the tribological and kinetic attributes of Ti chemical mechanical planarization (CMP) was investigated. Results indicated that processes at platen temperatures of 25 and 50 °C behaved similarly in terms of their tribological mechanism. At both temperatures, average coefficient of friction (COF) ranged from 0.19 to 0.41, indicating that boundary lubrication was the dominant tribological mechanism. Results also showed that average COF decreased with increasing platen temperature likely due to softening of pad asperities and lower slurry viscosity at the higher temperature. Due to exponentially accelerated chemical effects, Ti removal rate was higher when platen temperature was set at 50 °C. A two-step modified Langmuir–Hinshelwood model was used to simulate Ti removal rate and the chemical and mechanical rate constants under different polishing conditions. Simulated values of removal rate agreed well with experimental data. Simulated chemical rate to mechanical rate constant ratios suggested that the removal mechanism shifted from a more chemically-controlled to a more mechanically-controlled process as platen temperature was raised.

Tribological, thermal, and kinetic attributes of 300 vs. 450 mm chemical mechanical planarization processes

An existing 300 mm CMP tool has been modified to polish 450 mm wafers in order to demonstrate experimentally whether any differences exist in the tribological and thermal characteristics of the two processes, and from that, to infer whether one can expect any removal rate differences between the two systems. Results suggest that, within the ranges of parameter investigated, the two systems behave similarly in terms of their coefficients of friction and lubrication regimes. Additionally, it is shown that the 450 mm process, once adjusted for its platen velocity, runs only slightly warmer (by 1 to 2°C) than its 300 mm counterpart. Experimental data, coupled with copper removal rate simulations show that the wafer surface reaction temperatures of the 450 mm adjusted process are higher (by 2 to 3°C) than the 300 mm process. Consequently, simulated copper removal rates for the 450 mm adjusted process are higher (by 8 to 31%) than those of the 300 mm process.

Tribological and Kinetic Characterization of 300-mm Copper Chemical Mechanical Planarization Process

The tribological and kinetic attributes of 300-mm copper chemical mechanical planarization process were characterized in this study. Coefficient of friction (COF) ranged from 0.39 to 0.59 for the Cabot Microelectronics Corporation D100 concentrically grooved pad, indicating that boundary lubrication was the dominant tribological mechanism. In comparison, COF decreased sharply from 0.55 to 0.03 for the Dow Electronic Materials IC1000 Kgroove pad, indicating that the tribological mechanism transitioned from boundary lubrication to partial lubrication. For both pads, copper removal rate exhibited highly non-Prestonian behavior. A two-step modified Langmuir-Hinshelwood model was used to simulate copper removal rate, wafer surface reaction temperature, as well as chemical and mechanical rate constants. The simulated copper removal rates agreed very well with the experimental values. The simulated chemical rate constant to mechanical rate constant ratios indicated that the IC1000 pad generally produced a more mechanically controlled removal mechanism in this study.