MODEL 1064

ChipMillA fully integrated solution for millimeter-scale delayeringof both logic and memory semiconductor devices. The
ChipMill integrates signals from multiple detectors via an
artificial intelligence feedback control algorithm to adjust
milling parameters in real time. The result is the precise
removal of device layers and a highly planar surface.
• Nanometer flatness of the prepared area
• Milling area up to 10 x 10 mm• Automated sample height detection• User-friendly interface for the setup of millingparameters and display of images and analyticaldata

ION MILLING ANDFISCHIONE INSTRUMENTS
For more than three decades, Fischione Instruments has
been a world leader in ion milling for electron microscopy
applications. The company’s initial ion milling systems
were dedicated to transmission electron microscopy(TEM) specimen preparation. Through the years, Fischione
Instruments has gained significant expertise in ion source
technology to effectively mill and polish samples withoutcausing damage.
Within the same time frame, significant advances inelectron optics have occurred. Scanning electron
microscopy (SEM) performance is greatly enhanced,
particularly high-resolution imaging at low acceleratingvoltages. This advancement has increased the importanceof sample surface characteristics; mechanical preparation
artifacts are no longer acceptable.
As the market for ion milling for SEM developed, Fischione
Instruments extended its product line of suitable tools.
Currently, Fischione Instruments’ ion milling systems servea multitude of applications, including cross-section sample
preparation and polishing to support the structural andchemical analysis of various materials for multiple imaging
and analytical techniques, such as electron backscatter
diffraction (EBSD).
The Model 1064 ChipMill is a natural extension of theFischione Instruments’ product line.

• On-device touchscreen for managing sample
insertion and removal• End-pointing by time, chip structure, or chemicalcomposition• Components:› Ion source› Optical camera› Electron beam column› Secondary electron detector (SED)› Backscattered electron (BSE) detector› Energy dispersive X-ray spectrometer (EDS)› Secondary ion mass spectrometer (SIMS)M O D E L 10 6 4 C h i p M i l l

The sample preparation
breakthrough of the century
The Model 1064 ChipMill is a fully integrated
solution for large-scale delayering – up to a
10 x 10 mm milling area – of both memory andlogic semiconductor devices. Compared to allother methods, the ChipMill produces the flattest
surface over the largest area. The ChipMill’s
artifical intelligence automatically adjusts millingparameters to yield nanometer flatness within theprepared area.
The ChipMill reduces time and costs associatedwith research and development, manufacturing,
quality assurance, and failure analysis byyielding unsurpassed results. As the demand forsemiconductor devices grows, device sizes decrease,and architecture becomes more complex, theability to perform controlled delayering during allphases of the product life cycle is essential.
ChipMill components
The ChipMill contains an ion source to mill thesample, an optical camera to monitor milling
progress, a scanning electron microscope (SEM)

column working in conjunction with a secondary
electron detector (SED) and a backscatteredelectron (BSE) detector for sample imaging.
The electron beam also generates X-rays thatare analyzed by theenergy dispersive X-ray
The ChipMill
spectrometer (EDS)
produces the flattest
detector. A secondary
ion mass spectrometersurface over the(SIMS) yields surface
largest area
information.
Detector technology
When the sample surface is excited by theelectron beam, corresponding secondary electrons
are collected by the SED. Electron images are
displayed on one of the ChipMill’s monitors.
Backscattered electrons are produced by the elastic
scattering of the primary electron beam withatomic nuclei. Because information is generated by
the nucleus of the atom, an indication of elemental
composition becomes known.
By varying the electron beam accelerating
voltage, the electron penetration depth changes.

ChipMill components
Detectors and additional
components are attachedto the ChipMill chamber.
Clockwise from the top:
electron beam column;
energy-dispersive X-ray
spectrometer (EDS);
secondary electrondetector (SED); secondary
ion mass spectrometer(SIMS); load lock; ion
source; and backscatteredelectron detector (BSE) andoptical camera.

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M O D E L 10 6 4 C h i p M i l l

The ChipMill alters electron beam operating
parameters to distinguish between the surface layer
and the layer below.

During:

EDS detects X-rays emitted from the sample
surface, providing the elemental composition of
the delayered device.

• manufacturing, processes are improved toenhance performance and yield;

A SIMS system identifies the elemental
composition of the top device layer.

The role of electron microscopy insemiconductors
Electron microscopy is used to support every
phase of the semiconductor life cycle: research anddevelopment, manufacturing, quality control, andfailure analysis.

• research and development, circuit designs aredeveloped and verified;• quality control, chip reliability is evaluated; and• failure analysis, defects are identified andanalyzed.
Chips are comprised of multiple layers, with eachlayer having a thickness ranging from a few atomic
planes to several microns and node sizes of 3 nm
or less. The need for precise, controlled delayering
has never been more critical in supporting electron
microscopy’s role of understanding material
properties and chemistry at the atomic scale.

alternative delayering techniques
Various techniques are used for delayering. Mechanical polishing involves particles of a micron- or submicron scale abrasive compound to abrade the surface of the sample. However, these particles create
artifacts or scratches that potentially destroy important chip characteristics. Mechanical methods also do
not offer the ability to either precisely control the amount of material removed or predict the process end
point.
Etching removes material by subjecting the chip to various chemicals, which causes a chemical reaction thatremoves material from the chip surface. Depending upon the etchant chemistry, different materials within
the chip react at different etching rates; therefore, preferential or non-uniform material removal occurs.
Plasma, or reactive ion etching (RIE), is another method to remove material from the chip surface. RIE uses
combinations of ionized reactive gases and non-reactive gases. Reactive ions produce both a chemical
reaction and a sputtering effect. Non-uniformities in elemental composition, material density, and etchspecies can adversely impact etching rates and surface uniformity.
Broad ion beam milling is often employed to delayer chips. In this process, the center of the ion beam
typically has increased energy density as compared with its periphery, or tail. As a result, the center of thechip is milled faster than the edges. This creates a concave milling spot in the center where the ion beamis the strongest and a shallower depth at the edges where the ion beam density is weaker. This concave
surface profile precludes the ability to image and analyze features located within a large area of a single
chip layer.
More recent developments in delayering technology are FIB and plasma FIB (PFIB) technologies; whereby,
the ion beam is intensely focused. The drawbacks of these methods are a slow milling rate, a relatively small
milled area, and in some cases, the implantation of chemically reactive elements, such as gallium.

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M O D E L 10 6 4 C h i p M i l l

Additional techniques enabled by precise
delayering are electrical probing to test individual
circuits; metrology to measure feature sizes toensure compliance with design specifications; postmortem, single-defect failure analysis to remove
material until the fault location is revealed; andreverse engineering to delayer a chip in a serial
manner for the subsequent analysis of individuallayers.

Delayering workflow
Depackaging
Prior to ChipMillingSM, standard depackaging
techniques apply. These methods typically employ
mechanical or chemical processes that are better
suited to removing significant amounts of material
as compared to the precise thinning afforded by an
ion beam.
ChipMilling
Once the depackaged chip is mounted onto astandard SEM stub, it is transferred through the
ChipMill’s load lock and positioned on the sample
stage within the vacuum chamber.
Following the initial set-up procedure, the chipis ion milled until the predefined end point isachieved. In many cases, the end point is anindividual metal layer. After ChipMilling, the chipcan be transferred to any one of several analyticaldevices.
Preparing TEM specimens
The ChipMilled sample can be placed into a
focused ion beam (FIB) system for the site-specificextraction of transmission electron microscopy(TEM) lamellae.
Following post-FIB polishing in either a Fischione
Instruments’ Model 1040 NanoMill® TEMspecimen preparation system or Model 1080PicoMill® TEM specimen preparation system, thespecimen’s atomic-level structural and chemical
information can be ascertained via aberrationcorrected TEM imaging and analysis.
E.A. FISCHIONE INSTRUMENTS, INC.

ion beam generation
The ChipMill has a cylindrical ion beam witha maximum accelerating voltage of 10 keV.
Advanced ion optics allow the beam to maintainits profile over a length of up to 10 cm. Through amomentum transfer/sputtering process, material isejected from the sample in a precisely controlledmanner that yields uniform delayering.
The ion source uses electron impact ionization
technology. The source contains a filament
cartridge that initiates the flow of electrons,directing them into an ionization chamber. In theionization chamber, electrons interact with theprocess gas to create ions. Ions are subsequently
extracted and directed through the focusing
component of the ion source.
The exit of the ion source contains a beamsteering mechanism that deflects the ions in the Xand Y directions.
Applying Y-deflection bends the ion beam toward
the sample surface, and in combination with
the Z-offset of the sample stage, establishes theincident milling angle. Milling at a glancing angleachieves consistent milling.
The X-X raster function scans the ion beam acrossthe sample surface in a variably controlledmanner.
To establish planarity within an individual
layer, the ion beam must uniformly remove
material in a manner that is independent ofdevice geometry and elemental composition.
To achieve this objective, an in situ feedback
control system employs the output data from thevarious detectors to adjust ion source operating
parameters.
Raster control is automatically varied to correspondwith the sample material, area of interest, ion beamenergy, and ion beam current. Adjustments to theparameters needed to achieve uniform delayering
are automatically controlled to adjust the raster
pattern, raster rate, and the effective current
density per point. Information obtained fromthe sample surface is used to modify the beam
control parameters. This is the determining factor inachieving optimal surface flatness.

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The ChipMilling process
All system components are included within achamber that is evacuated by an oil-free vacuum
system.
A dedicated sample stage featuring X, Y, Z,and rotational movements provides proper
sample positioning in relation to various systemcomponents. Automated sample height detection
places the sample surface at the optimal milling
plane.
The ChipMill chamber design allows the ion
beam to project across the sample surface at a
glancing angle. The milling angle is established by
the combination of sample height control and theamount of vertical deflection applied to the ion
beam. The milling angle range is 0 to 10°.
While milling, the sample is continuously rotatedto minimize non-uniform milling of various
elements within the chip that sputter at different
rates. Typically, harder materials mill more slowly,
while softer materials mill more rapidly. This
results in curtaining. Sample rotation normalizes
milling and results in a planar surface.
Feedback from the sample surface
controls ion beam scanning
During milling, the ion beam scanning patternis controlled by an advanced algorithm which
processes the output of various detectors:• An optical camera captures interference fringes
to determine the material removal pattern.
• Electron beam sample interaction yields
secondary electrons that are captured by theEverhart-Thornley SED.
• Backscattered electrons result from the elastic
scattering of electrons from the primarybeam interaction with the sample surface; thebackscattered electrons assist in distinguishingdifferent layers within the device.
• X-rays emitted from the sample during
bombardment by the incident electron beam
are detected by the EDS system, which yields
elemental composition information.

E.A. FISCHIONE INSTRUMENTS, INC.

• Ions emitted during the milling process areanalyzed by the SIMS, which is a surfacesensitive technique for determining which layer
is exposed. It is useful in establishing if a layer isa metal, an oxide, or a nitride.
ChipMill’s artificial intelligence process
The ChipMill features an artificial intelligence(AI) process that incorporates a feedback control
loop to adjust the ion beam milling parameters inreal time. The ChipMill receives and analyzes datafrom the various detectors to quantify both surface
flatness and chemical composition of individual
device layers.
Depth profiles are calculated by the ion beam
control algorithm, which automatically adjusts theion beam raster pattern in terms of both dwell timeand current density per point while moving acrossthe delayered area. This method of continuous
feedback yields a highly planar sample surface.

System programing
The ChipMill is programmable through a standard
computer interface. System operating conditions
are programmed and viewed on a dedicatedmonitor. An on-board touchscreen, positioned next
to the load lock, facilitates sample exchange.
User controls can beplaced either adjacentto the ChipMill or in a
separate room.

End-pointing

The ChipMill’s
pioneering endpointing techniquerelies upon theacquisition of images
and analytical datato yield precise endpoint control

There are various
methods of end-point
detection, one of which
is time-based. However,for time-based endpointing to be effective, both layer thickness andmilling rate need to be very well understood.

The ChipMill’s pioneering end-pointing techniquerelies upon the acquisition of images and analyticaldata:
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Uniformity of device surface after delayering process
Three areas (Area 1, Area 2, and Area 3) of a chip were selected for observation following ChipMilling(top row); the observation areas are spaced 2 mm apart. Backscatter electron contrast images (middlerow) of the sample surface for each observation area are shown. Corresponding scanning transmission
electron microscopy (STEM) images (bottom row) are also shown. The difference between the three areasof observation across 8 mm is within 50 nm.

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M O D E L 10 6 4 C h i p M i l l• Ion milling exposes hierarchical circuit
information from each layer.

Maintenance and service• The accelerating voltage of the SEM electron
beam is increased to yield information relative tothe layer below the surface.

The ChipMill is covered by one of Fischione
Instruments’ service contract options. To expedite
service, the ChipMill has the capability of remotediagnostics. When connected to the Internet, theChipMill can be accessed by Fischione Instruments
Service for rapid troubleshooting and diagnostics
support.

• The data is correlated with the chemicalcomposition generated by the EDS and SIMS
systems to yield precise end point control.

To learn more about Fischione Instruments’comprehensive service and preventive maintenanceprograms, contact service@fischione.com.

• The SEM is operated at a given accelerating
voltage to yield information about the surface ofthe layer being milled.

E.A. Fischione Instruments, Inc.
9003 Corporate Circle
Export, PA 15632 USA
Tel: +1 724.325.5444
Fax: +1 724.325.5443
info@fischione.com
www.fischione.com©2022 E.A. Fischione Instruments, Inc. All rights reserved.
Model 1064 ChipMill technology U.S. patent pending.
NanoMill and PicoMill are registered trademarks of E.A. Fischione
Instruments, Inc. ChipMilling is a service mark of E.A. Fischione
Instruments, Inc.
Document Number PB1064 Revision 00 05/2022