Small Angle X-ray Scattering Metrology for Sidewall Angle and Cross Section of Nanometer Scale ...

48 Pages·2005·2.42 MB·English

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SSccaallee LLiinnee GGrraattiinnggss
Wen-Li Wu
Ronald L. Jones, Tengjiao Hu, Christopher L. Soles, Eric K. Lin,
Funding
•NIST Office of Microelectronics Programs
[email protected]
ULSI, Richardson, TX
March 18, 2005
• Introduction
•Measurement of pitch and line width
•Measurement of side wall angle & height
•Line roughness including both side walls & top surface
(on-going)
•Conclusions
ULSI, Richardson, TX
March 18, 2005
CCrriittiiccaall DDiimmeennssiioonn SSmmaallll AAnnggllee XX--rraayy
SSccaatttteerriinngg ((CCDD--SSAAXXSS))
Transmission SAXS
•Silicon transparent for E > 13 keV
•Developed using synchrotron technology
•Non-destructive / No sample prep
•Lab-scale device feasibility (in progress)
•Use scatterometry targets ω
•Beam spot size (40x40) µm
•Collection time: (1 to 5) seconds/sample
2θ
•Model fits simpler than scatterometry
•Measure “2-D” and Buried patterns of metals & dielectrics
•Via, post, pads, etc
•High Precision for small line width (10-300 nm)
•Sub-nm precision in pitch and linewidth
•Sidewall angle and Pattern Cross Section
•Technique “easier” with smaller structures
ULSI, Richardson, TX
March 18, 2005
Top down SEM of dense array of via pads
2-D and Buried Structures
•Structures can be buried (metrology of 3-
D circuits possible)
•Transmission measurement samples all
depths equally
•2-D detector allows single measurement
to characterize entire top-down shape.
•Additional measurements provide pattern
cross section (I.e. sidewall angle)
•Full 3-D characterization possible of
dense, high aspect ratio patterns
Resulting CD-SAXS detector image shows 2 axes of diffraction.
Entire top-down shape can be characterized in one measurement
ULSI, Richardson, TX
March 18, 2005
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Dense (1:1 spacing) 550 nm lines
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••PPhhoottoorreessiissttss ((224488 nnmm,, 119933 nnmm,, EEUUVV))
••EEnnggiinneeeerriinngg PPoollyymmeerrss ((PPMMMMAA,, PPSS))
••OOxxiiddeess ((SSiiOO22))
••NNaannooppoorroouuss MMaattrriicceess
••BBaarrrriieerr llaayyeerrss ((SSiiNN,, SSiiCCNN))
••MMeettaall IInntteerrccoonnnneeccttss ((CCuu))
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••LLiinnee//SSppaaccee ppaatttteerrnnss ((ggrraattiinnggss))
••AArrrraayyss ooff ccoolluummnnss
••AArrrraayyss ooff hhoolleess ((vviiaass))
Sparse (1:10 spacing) 15nm lines
Hexagonal Close Packed 60 nm vias
Line/Space Patterns in Oxide
FILE: ISMT_S103_R_046.dat Model Name: Rectangle
Period (nm): 173
Line Width (nm): 15
3 Line Height (nm): 370
Dev. in Period (nm): 4
Pattern SLD (cm^-2): 1e+10
Scale Factor: 6
Background: 600
2
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0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
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qU (nLmS) I, Richardson, TX
x
March 18, 2005
CCrriittiiccaall DDiimmeennssiioonn SSmmaallll AAnnggllee XX--rraayy
SSccaatttteerriinngg ((CCDD--SSAAXXSS))
• Probing wavelength < 1 Å → measurement
becomes easier as feature size gets smaller
• Weak interaction between materials ( Cu,
Ta, Si, C, O, H, etc.) → penetration power
& Fourier transform (real objects)
• Absorption edge exists for heavy elements
including Ta
ULSI, Richardson, TX
March 18, 2005
challenges
• Quantify imperfections of nano-pattern
from X-ray data
• Availability of intense x-ray source other
than synchrotron
ULSI, Richardson, TX
March 18, 2005
• Introduction
•Measurement of pitch and line width
•Measurement of side wall angle and height
•Line roughness including both side walls & top surface
(on-going)
•Conclusions
ULSI, Richardson, TX
March 18, 2005
SAXS characterization technique
• Pitch Measurement
0.030
0.025
0.020
)
1
0.015
-
A
(

q 0.010
0.005
0.000
-10 -5 0 5 10
D Peak order
D = 237.1 ± 0.5 nm
ULSI, Richardson, TX
March 18, 2005
3
2
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n
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1000
9
8
7
6
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
-1
q (nm )
x
ULSI, Richardson, TX
March 18, 2005