TY - JOUR
T1 - Characterization of CMP slurries using densitometry and refractive index measurements
AU - Bengochea, Leticia Vazquez
AU - Sampurno, Yasa
AU - Kavaljer, Marcus
AU - Johnston, Rob
AU - Philipossian, Ara
N1 - Funding Information:
This research received no external funding. The authors wish to acknowledge Reyes Sierra Alvarez for allowing us to use her Malvern Zetasizer Nano ZS instrument for dynamic light scattering measurements.
Publisher Copyright:
© 2018 by the authors.
PY - 2018/10/24
Y1 - 2018/10/24
N2 - We investigated the possibility of employing refractive index (RI) measurements for inline incoming slurry control at the point of use (POU), as an alternative to the widespread densitometry method. As such, it became necessary to determine if RI could detect smaller changes in slurry composition and, therefore, provide a tighter control. Three industrially-relevant silica-based slurries, namely, Fujimi PL-7106, Klebosol 1501-50, and CMC W7801, were characterized using both densitometry and RI measurements. Initial solutions of the three slurries were prepared and increasingly small amounts of ultrapurified water (UPW) were added to study the change in slurry properties. Results showed that both density and RI decreased linearly with the addition of water for all three slurries, with the 1501-50 being the most sensitive to water addition. A linear correlation between the two properties was found, with R2 values that exceeded 0.95 in all cases. Furthermore, the approximate limit of detection of both metrology tools was estimated based on the slope of the fitting line and resolution. When compared to densitometry, RI was found to be the far superior method for detecting smaller changes in water concentration.
AB - We investigated the possibility of employing refractive index (RI) measurements for inline incoming slurry control at the point of use (POU), as an alternative to the widespread densitometry method. As such, it became necessary to determine if RI could detect smaller changes in slurry composition and, therefore, provide a tighter control. Three industrially-relevant silica-based slurries, namely, Fujimi PL-7106, Klebosol 1501-50, and CMC W7801, were characterized using both densitometry and RI measurements. Initial solutions of the three slurries were prepared and increasingly small amounts of ultrapurified water (UPW) were added to study the change in slurry properties. Results showed that both density and RI decreased linearly with the addition of water for all three slurries, with the 1501-50 being the most sensitive to water addition. A linear correlation between the two properties was found, with R2 values that exceeded 0.95 in all cases. Furthermore, the approximate limit of detection of both metrology tools was estimated based on the slope of the fitting line and resolution. When compared to densitometry, RI was found to be the far superior method for detecting smaller changes in water concentration.
KW - Chemical mechanical planarization
KW - In-line monitoring and control
KW - Semiconductor technology
KW - Slurry characterization
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U2 - 10.3390/mi9110542
DO - 10.3390/mi9110542
M3 - Article
AN - SCOPUS:85055736887
SN - 2072-666X
VL - 9
JO - Micromachines
JF - Micromachines
IS - 11
M1 - 542
ER -