New interferometric measurement technique for small diameter TSV

Author

Timoney, Padraig ; Fisher, Daniel ; Yeong-Uk Ko ; Vaid, Alok ; Thangaraju, Sara ; Smith, D. ; Kamineni, Himani ; Dingyou Zhang ; Alapati, Ramakanth ; Wonwoo Kim ; Ke Xiao ; Edmundson, H. ; Smith, Nadia ; Peterson, Bela ; Amin, Hayder ; Peak, Joseph ; John

Author_Institution

GLOBALFOUNDRIES US Inc., Malta, NY, USA

fYear

2014

fDate

19-21 May 2014

Firstpage

37

Lastpage

41

Abstract

High aspect ratio through silicon vias (TSV) present a challenge for measurement of bottom critical dimension (BCD) and depth. TSVs smaller than 5 micron diameter with greater than 12:1 depth to BCD aspect ratio have particularly poor signal to noise ratio in the measured signal. This paper proposes a method for improving the interferometric measurement of these very small and high-aspect ratio TSVs with data showing the feasibility of measuring both BCD and depth of 19:1 aspect ratio TSVs. This work demonstrates the capability to analyze the scanning white-light interferometry (SWLI) signal for such high aspect ratio TSV BCD and depth measurements with >0.95 R² correlation to reference metrology obtained through cross section SEM. Precision of within 2.5% of nominal BCD and within 0.1% of nominal depth was demonstrated for 10x repeatability measurements.

Keywords

integrated circuit measurement; interferometers; light interferometry; scanning electron microscopy; spatial variables measurement; three-dimensional integrated circuits; BCD; SWLI signal; bottom critical dimension; cross section SEM; depth measurements; high aspect ratio through silicon vias; interferometric measurement technique; reference metrology; scanning white-light interferometry signal; signal to noise ratio; small diameter TSV; Correlation; Interference; Noise; Optical interferometry; Surface topography; Through-silicon vias; BCD; Interferometry; TCD; TSV; critical dimension; depth; high aspect ratio; small;

fLanguage

English

Publisher

ieee

Conference_Titel

Advanced Semiconductor Manufacturing Conference (ASMC), 2014 25th Annual SEMI

Conference_Location

Saratoga Springs, NY

Type

conf

DOI

10.1109/ASMC.2014.6846973

Filename

6846973