Scavenger with Protonated Phosphite Ions for Incredible Nanoscale ZrO2-Abrasive Dispersant Stability Enhancement and Related Tungsten-Film Surface Chemical-Mechanical Planarization.

Seong-In Kim,Jin-Hyung Park,Jea-Gun Park,Jong-Chan Lee,Jae-Young Bae,Jun-Myeong Lee,Seung-Jae Lee,Gi-Ppeum Jeong

doi:10.3390/nano11123296

Abstract

For scaling-down advanced nanoscale semiconductor devices, tungsten (W)-film surface chemical mechanical planarization (CMP) has rapidly evolved to increase the W-film surface polishing rate via Fenton-reaction acceleration and enhance nanoscale-abrasive (i.e., ZrO2) dispersant stability in the CMP slurry by adding a scavenger to suppress the Fenton reaction. To enhance the ZrO2 abrasive dispersant stability, a scavenger with protonate-phosphite ions was designed to suppress the time-dependent Fenton reaction. The ZrO2 abrasive dispersant stability (i.e., lower H2O2 decomposition rate and longer H2O2 pot lifetime) linearly and significantly increased with scavenger concentration. However, the corrosion magnitude on the W-film surface during CMP increased significantly with scavenger concentration. By adding a scavenger to the CMP slurry, the radical amount reduction via Fenton-reaction suppression in the CMP slurry and the corrosion enhancement on the W-film surface during CMP performed that the W-film surface polishing rate decreased linearly and notably with increasing scavenger concentration via a chemical-dominant CMP mechanism. Otherwise, the SiO2-film surface polishing rate peaked at a specific scavenger concentration via a chemical and mechanical-dominant CMP mechanism. The addition of a corrosion inhibitor with a protonate-amine functional group to the W-film surface CMP slurry completely suppressed the corrosion generation on the W-film surface during CMP without a decrease in the W- and SiO2-film surface polishing rate.

Highlights

Nanoscale semiconductor devices have been rapidly scaling down to achieve faster switching, lower power consumption, and lower bit cost; that is, less than a 14 nm design rule for dynamic random-access memory (DRAM), higher than 128-floor memorycells for three-dimensional (3D) NAND flash memory, and less than 5 nm design rule for application processors [1,2,3,4,5]
The normalized XPSpeak intensity at the W-metal increased almost linearly with the scavenger concentration. These results indicate that the addition of a scavenger to the W-film surface chemical mechanical planarization (CMP) slurry reduced the chemical oxidation magnitude (i.e., WO3 ) on the W-film surface; that is, the chemical oxidation magnitude on the W-film surface decreased clearly with increasing scavenger concentration
After CMP, the normalized X-ray photoelectron spectroscopy (XPS)-peak intensity of Si–OH on the SiO2 -film surface peaked at a scavenger concentration of 0.10 wt%, while that of SiO2 on the SiO2 -film surface was minimized at the same scavenger concentration. These results indicate that the normalized XPS-peak intensity of Si–OH on the SiO2 -film surface depending on the scavenger concentration was well correlated with the SiO2 -film polishing rate depending on the scavenger concentration

Summary

Introduction

Nanoscale semiconductor devices have been rapidly scaling down to achieve faster switching, lower power consumption, and lower bit cost; that is, less than a 14 nm design rule for dynamic random-access memory (DRAM), higher than 128-floor memorycells for three-dimensional (3D) NAND flash memory, and less than 5 nm design rule for application processors [1,2,3,4,5]. A nanoscale thick WO3 layer on the W-film surface. The produced radicals accelerate the Fenton reaction, which is called a cycling chemical reaction process [12,13]. To enhance the W-film polishing rate during CMP, the Fenton reaction between a ferric–ionic catalyst and oxidant (i.e., H2 O2 ) was essentially accelerated by designing ferric–ionic catalysts properly and increasing the oxidant concentration, which is a chemical-dominant CMP mechanism. The acceleration of the Fenton reaction in the W-film surface CMP slurry can induce a remarkable degradation of the nanoscale abrasive dispersant stability in the CMP slurry, resulting in fast sedimentation of the nanoscale abrasives in the CMP slurry during CMP [10]

Methods

Results

Conclusion