Dimensional Metrology for

Nanomanufacturing

POLYMERS

Our goal is to develop measurements that quantify pattern shape, size, 

and orientation as a tool to quantitatively evaluate nanofabrication 

and assembly processes. Our customers range from the semiconductor 

fabrication community, where the dimensional metrology needs are 

well-documented by industry roadmaps and critical to quality control, 

to emerging technology sectors, such as bit patterned magnetic data 

storage media, where quantitative feedback is critical to developing and 

optimizing nontraditional nanofabrication routes. Our unified approach 

is to develop nondestructive scattering and reflectivity measurements 

using X-rays and neutrons as a high-resolution and quantitative pattern 

shape metrology.

Objective

Impact and Customers

• Directly addressing the “Grand Challenges” of the International 

Technology Roadmap for Semiconductors, a document that articulates 

the lack of measurement solutions for pattern uniformity and placement 

in dense arrays of sub-50 nm structures which are the foundation of 

next generation electronics and data storage devices.

• Critical Dimension Small Angle X-ray Scattering (CD-SAXS) achieves 

the first example of 3D metrology for interconnects. Preliminary 

measurements on FINFET structures demonstrate the feasibility of application to these buried structures. Such 

measurements are not possible with current methods.

• A NIST collaboration with IBM and Hitachi Global Data Storage has provided the 

distribution of orientation of self-assembled structures, a key indicator of pattern 

quality necessary for technology development, using Rotational Small Angle Neutron 

Scattering (R-SANS).

• CD-SAXS is included on the 2007 ITRS Update as a candidate next generation critical 

dimension pattern metrology technology for the semiconductor industry.

• Customers include Intel, SEMATECH, IBM, and Hitachi Glabal Data Storage.

Approach

Materials Science and Engineering Laboratory

Scattering and reflectivity techniques, i.e., measurements in reciprocal 

space, are employed to measure, with sub-nm precision, pattern 

shape, physical dimensions, and orientation for periodic arrays of 

nanostructures. Critical Dimension Small Angle X-ray Scattering (CDSAXS) utilizes the transmission scattering from a small beam size (100 x 

100 μm) to provide detailed shape and dimensional data for 10 to 500 

nm structures placed with high uniformity in pitch. A lab scale prototype 

at NIST complements the current optical scatterometry, CD-AFM, and CD-SEM methods that are widely used in the 

nanofabrication community. CD-SAXS can easily quantify the pattern shape in arrays of nanostructures with periodicities 

in the range of 10 to 500 nm with sub-nm precision, is nondestructive, is capable of quantifying buried or free-standing 

patterns, and is straightforward to interpret via scattering theory. Rotational Small Angle Neutron Scattering (R-SANS) is a 

complementary technique capable of measuring the distribution in orientation for patterning methods based on directed 

self-assembly. These unique dimensional measurements are applied to evaluate emerging nanofabrication processes 

including extreme ultraviolet lithography, electron beam lithography, and block copolymer directed self-assembly.

854-02-01a
Non-Planar Electronics: In order to 

meet future challenges from thermal and 

power efficiency requirements of sub 32nm 

technology nodes, transistor architecture 

is migrating from planar to non-planar 

structures. These structures, such as the trigate and FinFET devices, feature increased 

complexity in pattern shape and nanoscale 

conformal coatings. Current measurement 

platforms are challenged by the small 

dimensions inherent in these structures, 

where diminishingly small variations in 

composition and dimensions will reduce 

or eliminate device functionality. Critical 

Dimension Small Angle X-ray Scattering 

(CD-SAXS) is a metrology platform with 

the potential capability to quantify 3-

dimensional non-planar structure with 

sub-nm precision. Specifically, CD-SAXS 

has the potential to non-destructively 

characterize the thickness and, to a limited 

extent the uniformity of the thickness, of 

the conformal high-k dielectric layer.

In FY08, we have demonstrated this 

capability of X-ray based scatterometry 

by measuring high-k dielectric layers 

deposited from 0 to10nm in thickness over 

grating patterns with a nominal critical 

dimension of 20 nm. For these patterns, 

CD-SAXS provides high precision data 

on average high-k dielectric thickness, 

line width (CD), and pitch. In addition, 

the measurement has the capability to 

measure the average top layer thickness 

and the dielectric thickness on the pattern 

sidewall independently, providing a 

measure of uniformity.

Orientation in Directed Assembly:

Di-block copolymers are polymeric chains 

composed of two covalently linked subchains that can assemble into nanoscale 

domains. Morphologies achieved to date 

include spherical, cylindrical, lamellar, 

and bicontinuous phases. The capability 

to assemble these polymers within a thin 

coating to achieve phases with narrow size 

disparity makes them attractive as sacrificial 

resists as well as functional materials. 

However, control over orientation requires 

external guides and control over processing 

conditions.

A wide array of strategies have been 

employed to date to create large area 

films with nearly single crystalline order 

including solvent annealing, chemical 

pattern templates, topological templates, 

and electric fields. Challenges still exist 

in the precise measurement of block 

copolymer orientation, particularly in 

thick films and during early stages of 

processing, where electron microscopy is 

frequently destructive and X-ray contrast 

is often low. To address this challenge 

for block copolymer (BCP) films and 

other nanoscale soft matter systems, we 

are developing Rotational Small Angle 

Neutron Scattering.

Rotation Small Angle Neutron Scattering, 

in conjunction with specular neutron 

reflectivity, can measure the relative 

fractions of perpendicular and parallel 

components. Shown are data from a 

“mixed” state film, where one phase is 

perdeuterated, measured along the Qx

-

Qz

 plane. The hexagonal diffraction 

spots are indicative of several layers of 

ordered cylinders parallel to the substrate. 

Neutron reflectivity reveals these cylinders 

as located near the bottom substrate. 

These data indicate the perpendicular 

cylinders become more dominant as film 

thickness increases, providing a detailed 

picture of coexisting orientations with the 

relative fractions varying with thickness 

and annealing temperature.

Materials Science and Engineering Laboratory

Accomplishments

Kevin Yager

Gus Bosse

Chengqing Wang

Derek Ho

Kwang Woo Choi (Intel assignee)

Sancheol Kim

Xiao-hua Zhang

Nathaniel Fredin

Wen-li Wu

Christopher Soles

Ronald Jones

(Polymers Division)

(301) 975-4624

rljones@nist.gov

www.nist.gov/polymers

Learn More Publications

y

Zhang X, Berry BC, Yager KG, Kim S, Jones RL, Satija S, Pickel DL, Douglas JF and Karim A Surface 

Morphology Diagram for Cylinder Forming Block Copolymer Films ACS Nano, 2: 2331 (2008)

Wang CW, Choi KW, Jones RL, Soles CL, Lin EK, Wu WL, Clarke JS, Villarrubia, JS and Bunday B 

Linewidth Roughness and Cross-sectional Measurements of Sub-50 nm Structures with CD-SAXS and 

CD-SEM SPIE Proceedings: Metrology, Inspection, and Process Control for Microlithography XXIII, 

6922: 69221Z (2008)

Wang CW, Choi KW, Fu WE, Ho DL, Jones RL, Soles CL, Lin EK, Wu WL, Clarke JS and Bunday 

B CD-SAXS Measurements Using Laboratory-based and Synchrotron-based Instruments SPIE 

Proceedings: Metrology, Inspection, and Process Control for Microlithography XXIII, 6922: 692212E 

(2008)

Yager KG, Berry BC, Page K, Patton D, Karim A and Amis EJ Disordered Nanoparticle Interfaces for 

Directed Self-Aseembly Soft Matter, 5: 622 (2009)

Block copolymer orientation as measured by 

top-down microscopy. The processing conditions, 

in this case the annealing temperature and film 

thickness, dictate the orientation of nanoscale 

cylindrical phases. However, microscopy does not 

reveal the structure below the top surface indicated 

in the cross section schematic.

R-SANS data collected for a block copolymer 

film during directed self-assembly. Shown is a 

Fourier space image of diffraction from nanoscale 

cylindrical phases, where two orientations co-exist.

CD-SAXS data from a model tri-gate structure 

patterned in a line/space array (top) and the 

resulting model used to fit the data (bottom). 

Dimensions resolved include the pitch, line width, 

line height, sidewall angle, and dielectric thickness.