U.S. patent application number 13/226931 was filed with the patent office on 2011-12-29 for gas ion source with high mechanical stability.
Invention is credited to Thomas Jasinski, DIETER WINKLER.
Application Number | 20110315890 13/226931 |
Document ID | / |
Family ID | 38938538 |
Filed Date | 2011-12-29 |
![](/patent/app/20110315890/US20110315890A1-20111229-D00000.png)
![](/patent/app/20110315890/US20110315890A1-20111229-D00001.png)
![](/patent/app/20110315890/US20110315890A1-20111229-D00002.png)
![](/patent/app/20110315890/US20110315890A1-20111229-D00003.png)
![](/patent/app/20110315890/US20110315890A1-20111229-D00004.png)
![](/patent/app/20110315890/US20110315890A1-20111229-D00005.png)
United States Patent
Application |
20110315890 |
Kind Code |
A1 |
WINKLER; DIETER ; et
al. |
December 29, 2011 |
GAS ION SOURCE WITH HIGH MECHANICAL STABILITY
Abstract
A gas field ion source is described for a charged particle beam
device having a charged particle beam column. The gas field ion
source includes an emitter unit, a cooling unit, and a thermal
conductivity unit for thermal conductivity from the cooling unit to
the emitter unit, wherein the thermal conductivity unit is adapted
for reduction of vibration transfer from the cooling unit to the
emitter unit.
Inventors: |
WINKLER; DIETER; (Munich,
DE) ; Jasinski; Thomas; (Munich, DE) |
Family ID: |
38938538 |
Appl. No.: |
13/226931 |
Filed: |
September 7, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12199574 |
Aug 27, 2008 |
8044370 |
|
|
13226931 |
|
|
|
|
Current U.S.
Class: |
250/423F ;
29/428 |
Current CPC
Class: |
H01J 2237/0807 20130101;
H01J 2237/0216 20130101; F25B 2500/13 20130101; H01J 2237/002
20130101; Y10T 29/49826 20150115; H01J 27/26 20130101; H01J 37/28
20130101; H01J 2237/061 20130101; F25D 19/006 20130101; H01J 37/08
20130101 |
Class at
Publication: |
250/423.F ;
29/428 |
International
Class: |
H01J 27/02 20060101
H01J027/02; B23P 11/00 20060101 B23P011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 27, 2007 |
EP |
07016766.3 |
Claims
1. A gas field ion source for a charged particle beam device having
a charged particle beam column, comprising: an emitter unit; a
cooling unit; a thermal conductivity unit for thermal conductivity
from the cooling unit to the emitter unit, wherein the thermal
conductivity unit is adapted for reducing vibration transfer from
the cooling unit to the emitter unit; and an emitter unit support
for connecting the emitter unit with a portion of the charged
particle beam column, wherein the emitter unit is indirectly
connected to the cooling unit.
2. The gas field ion source according to claim 1, wherein the
cooling unit is mechanically decoupled from the emitter unit with
regards to vibrations from the emitter unit.
3. The gas field ion source according to claim 1, wherein the
emitter unit support is adapted for reducing vibration transfer
from the cooling unit to the charged particle column.
4. The gas field ion source according to claim 1, wherein the
thermal conductivity unit includes a flexible wire, stripe or
braid.
5. The gas field ion source according to claim 4, wherein the
flexible wire or braid consist of a material with a thermal
conductivity of 100 W/(mK) or higher.
6. The gas field ion source according to claim 4, wherein the
flexible wire or braid includes at least a material selected from
the group consisting of: copper, aluminum, brass, silver, and a
combination thereof.
7. The gas field ion source according to claim 4, wherein the wire
or braid of the thermal conductivity unit is extended between a
protruding portion of the cooling unit and a protruding portion of
the emitter unit.
8. The gas field ion source according to claim 7, wherein the
protruding portion of the cooling unit and the protruding portion
of the emitter unit overlap in a first direction, and wherein the
wire or braid extends in a plane perpendicular to the first
direction.
9. The gas field ion source according to claim 1, wherein the
thermal conductivity unit includes a gas filled space.
10. The gas field ion source according to claim 1, further
comprising: an emitter module, comprising: an emitter holder; an
emitter structure; a detachably connectable electrical connection
assembly of the emitter module; and a detachably connectable gas
supply connection assembly of the emitter module; and a supply
module, the supply module comprising: at least one electrical
conductor for providing voltage and/or current; a gas supply
conduit; a thermal conductor; a detachably connectable electrical
connection assembly of the supply module; and a detachably
connectable gas supply connection assembly of the supply module,
wherein the emitter module and the supply module are detachably
connectable by the detachably connectable connection assemblies of
the emitter module and the detachably connectable connection
assemblies of the supply module.
11. The gas field ion source according to claim 10, wherein the
emitter module further comprises a detachably connectable thermal
conductivity connection assembly of the emitter module, and wherein
the supply module further comprises a detachably connectable
thermal conductivity connection assembly of the supply module.
12. The gas field ion source according to claim 1, wherein the
emitter unit comprises: a base; a supporting wire connected to the
base; and an emitter tip connected to the supporting wire.
13. A charged particle beam device, comprising: a gas field ion
source for a charged particle beam device having a charged particle
beam column, the gas field ion source comprising: an emitter unit;
a cooling unit; a thermal conductivity unit for thermal
conductivity from the cooling unit to the emitter unit, wherein the
thermal conductivity unit is adapted for reduced vibration transfer
from the cooling unit to the emitter unit; and an emitter unit
support for connecting the emitter unit with a portion of the
charged particle beam column, wherein the emitter unit is
indirectly connected to the cooling unit.
14. A method of manufacturing a charged particle beam device having
a charged particle beam column and a gas field ion source with an
emitter unit and a cooling unit, comprising: mounting the emitter
unit and the cooling unit mechanically decoupled from each other to
the charge particle beam column; and providing a mechanically
decoupling thermal conductivity unit between the emitter unit and
the cooling unit.
15. The method of manufacturing a charged particle beam device
according to claim 14, further comprising: reducing vibration
transfer from the cooling unit to the charged particle beam
column.
16. The method of manufacturing a charged particle beam device
according to claim 14, further comprising: placing an emitter
structure having a base, a supporting wire and an emitter tip in an
emitter holder of the emitter unit.
17. The method of manufacturing a charged particle beam device
according to claim 14, further comprising: aligning the emitter
structure in the charged particle beam column.
18. The method of manufacturing a charged particle beam device
according to claim 14, wherein the cooling unit is mechanically
decoupled from the emitter unit with regards to vibrations from the
emitter unit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of co-pending
U.S. patent application Ser. No. 12/199,574 (Attorney docket No.
ZIMR/0109), filed on Aug. 27, 2008.
FIELD OF THE INVENTION
[0002] Embodiments described herein generally relate to a charged
particle beam device and a method of manufacturing and/or
maintaining charged particle beam devices. In particular,
embodiments relate to a gas field ion source of a charged particle
beam device. More particularly, it relates to mechanical stability
of gas field ion sources. Specifically, it relates to a gas field
ion source, a charged particle beam device and a method of
manufacturing a gas field ion source.
BACKGROUND OF THE INVENTION
[0003] Charged particle beam apparatuses have many functions in a
plurality of industrial fields, including, but not limited to,
inspection of semiconductor devices during manufacturing, exposure
systems for lithography, detecting devices and testing systems.
Thus, there is a high demand for structuring and inspecting
specimens within the micrometer and nanometer scale.
[0004] Micrometer and nanometer scale process control, inspection
or structuring is often done with charged particle beams which are
generated and focused in charged particle beam devices. Examples of
charged particle beam devices are electron microscopes, electron
beam pattern generators, ion microscopes as well as ion beam
pattern generators. Charged particle beams, in particular ion
beams, offer superior spatial resolution compared to photon beams,
due to their short wave lengths at comparable particle energy.
[0005] Besides electron microscopes, which include electron
sources, microscopes including gas field ion sources for charged
particle beam devices are considered. Thereby, for example, an
increase in resolution might be realized. Accordingly, gas field
ion sources are promising for use in very high resolution
applications. In order to enable very high resolutions, a variety
of system requirements have to be considered.
SUMMARY OF THE INVENTION
[0006] In light of the above, the present invention provides a gas
field ion source according to independent claim 1, a charged
particle device according to claim 13 and a method for
manufacturing of a gas field ion source according to independent
claim 14.
[0007] According to one embodiment, a gas field ion source is
provided. The gas field ion source includes an emitter unit, a
cooling unit, and a thermal conductivity unit for thermal
conductivity from the cooling unit to the emitter unit, wherein the
thermal conductivity unit is adapted for reducing vibration
transfer from the cooling unit to the emitter unit, and an emitter
unit support for connecting the emitter unit with a portion of the
charged particle beam column, wherein the emitter unit is
indirectly connected to the cooling unit.
[0008] According to another embodiment, a charged particle beam
device is provided. The charged particle beam device includes a gas
field ion source. The gas field ion source includes an emitter
unit, a cooling unit, and a thermal conductivity unit for thermal
conductivity from the cooling unit to the emitter unit, wherein the
thermal conductivity unit is adapted for reduction of vibration
transfer from the cooling unit to the emitter unit or for reducing
vibration transfer from the cooling unit to the emitter unit, and
an emitter unit support for connecting the emitter unit with a
portion of the charged particle beam column, wherein the emitter
unit is indirectly connected to the cooling unit and wherein the
emitter unit is indirectly connected to the cooling unit.
[0009] According to a further embodiment, a method of manufacturing
a charged particle beam device having a charged particle beam
column and a gas field ion source with an emitter unit and a
cooling unit. The method includes mounting the emitter unit and the
cooling unit mechanically decoupled from each other to the charge
particle beam column, and providing a mechanically decoupling
thermal conductivity unit between the emitter unit and the cooling
unit.
[0010] Further advantages, features, aspects and details that can
be combined with the above embodiments are evident from the
dependent claims, the description and the drawings.
[0011] Embodiments are also directed to apparatuses for carrying
out the disclosed methods and including apparatus parts for
performing each described method steps. These method steps may be
performed by way of hardware components, a computer programmed by
appropriate software, by any combination of the two or in any other
manner. Furthermore, embodiments are also directed to methods by
which the described apparatus operates, is manufacture or is
maintained. It includes method steps for carrying out every
function of the apparatus, manufacturing every part of the
apparatus, or maintaining the apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Some of the above indicated and other more detailed aspects
of the invention will be described in the following description and
partially illustrated with reference to the figures. Therein:
[0013] FIG. 1 shows a schematic view of a charged particle beam
device including an emitter and a cooling unit according to
embodiments described herein;
[0014] FIG. 2 shows a schematic view of a portion of a charged
particle beam device including an emitter and a cooling unit
according to embodiments described herein;
[0015] FIG. 3 shows a schematic view of a portion of another
charged particle beam device including an emitter and a cooling
unit according to embodiments described herein;
[0016] FIG. 4 shows a schematic view of a portion of an even
further charged particle beam device including an emitter and a
cooling unit according to embodiments described herein;
[0017] FIG. 5A shows a schematic side view of a portion of a
charged particle beam device including an emitter and a cooling
unit according to embodiments described herein;
[0018] FIG. 5B shows a schematic top view of FIG. 5A;
[0019] FIG. 6 shows a schematic side view of a portion of yet
another charged particle beam device including an emitter and a
cooling unit according to embodiments described herein;
[0020] FIG. 7 shows a schematic view of a charged particle beam
device including an emitter and a cooling unit according to
embodiments described herein; and
[0021] FIG. 8 shows a schematic view of a charged particle beam
device including an emitter and a cooling unit according to further
embodiments described herein.
DETAILED DESCRIPTION OF THE DRAWINGS
[0022] Without limiting the scope, in the following, the charged
particle beam device or components thereof will exemplarily be
referred to as an ion beam device or components thereof, which
detect secondary and/or backscattered electrons. Thereby, the
secondary and/or backscattered electrons might be especially
utilized during inspection or lithography. The present invention
can still be applied for apparatuses and components using other
secondary and/or backscattered charged particles to obtain a
specimen image, to control patterning of a specimen, for testing,
imaging, inspection applications or during specimen modification
applications like sputtering, milling or the like.
[0023] Within the following description of the drawings, the same
reference numbers refer to the same components. Generally, only the
differences with respect to the individual embodiments are
described.
[0024] FIG. 1 shows a charged particle beam device 100. According
to embodiments described herein, the charged particle beam device
includes a charged particle beam column. Therein, a gun chamber 21
and a further chamber 24 is provided. Within the gun chamber 21 an
emitter unit 150 is provided. According to some embodiments, the
emitter unit can includes an emitter, e.g., a sharpened single
crystal, which is for example made of tungsten, iridium, or the
like and which is welded to a supporting wire. Further, a base can
be provided. The supporting wire is fixed to the base. According to
further embodiments described herein, the base can include a
ceramic material.
[0025] The emitter unit emits an ion beam essentially along an
optical axis of the charged particle beam device. The ion beam can
be guided and shaped by beam shaping means like apertures, lenses,
deflectors and the like. An objective lens focuses the ion beam on
specimen 5, which is positioned on specimen holder 50. On
impingement of the primary ion beam on the specimen 5 secondary
and/or backscattered particles are released. The secondary and/or
backscattered particles can be used for inspection, testing, image
generation, or the like. This can be done for testing, imaging
and/or inspection applications or during specimen modification
applications like sputtering, milling or the like.
[0026] According to embodiments described herein, the emitter unit
150 is connected to the charged particle beam column with the
connection element acting as an emitter unit support 155. FIG. 1
refers to embodiments, wherein the emitter unit supports connects
the emitter unit to a structure between the gun chamber 21 and the
further chamber 24.
[0027] However, according to other embodiments, it is also possible
to connect the emitter unit 150 to other portions of the charged
particle beam column. According to different embodiments, the
emitter unit can be connected to the charged particle beam column,
a housing portion, or a structure portion of the column of the
charged particle beam device, directly or indirectly.
[0028] For the embodiments in which the emitter unit is directly
connected to charged particle beam column, the emitter unit support
155 is connected directly to a portion of the charged particle beam
column and directly to the emitter unit.
[0029] For the embodiments in which the emitter unit is indirectly
connected to the charged particle beam column, the emitter unit
support 155 is connected to other elements, which are in turn
connected to the charged particle beam column. However, according
to embodiments described herein, the emitter unit is connected to
the charged particle beam column not via the cooling unit 146. A
main source of vibration transfer from the cooling unit to the
emitter unit can be avoided by omitting this connection.
[0030] Nevertheless, the cooling unit for cooling the emitter unit
should still have a thermal conductivity path to the emitter
unit.
[0031] Therefore, the cooling unit 146 is connected to the column
of the charged particle beam device 100 via a vibration decoupling
unit 162. Thereby, in particular, the cooling unit 146 is
mechanically decoupled with regard to vibrations from the emitter
unit 150. The cooling unit and the emitter unit are mechanically
decoupled.
[0032] According to further embodiments, which can be combined with
any of the embodiments described herein, the cooling unit can
include any of the following systems: The cooling unit may be
cryo-cooler, e.g, open or closed cycle coolers, open or closed
cycle Helium coolers, open or closed cycle nitrogen coolers, a
combination thereof or another cooler. Particular examples can be
pulse tube coolers or GM cooler (Gifford McMahon cooler).
[0033] FIG. 1 further shows a thermal conductivity unit 164, which
cools the emitter unit and the emitter tip, respectively. According
to different embodiments, the thermal conductivity unit for thermal
conductivity from the cooling unit to the emitter unit is provided
to reduce or avoid transfer of vibrations or other mechanical
influences from the cooling unit 146 to the emitter unit 150.
[0034] Generally, a reduced transfer of vibrations can also be
considered an increased vibration isolation. According some
embodiments described herein, which can be combined with any of the
other embodiments, a reduced vibration transfer of the thermal
conductivity unit can be defined with regard to damping of the
vibrations of the cooling unit. According to different embodiments,
vibrations from the cooling unit should be damped by the thermal
conductivity unit by at least a factor of 10, a factor of 30 or
even a factor of 100.
[0035] According to one embodiment, as shown in FIGS. 1 and 2, the
thermal conductivity unit 164 is provided by a flexible, loosely
hanging heat conducting means. As an example, metal wires like
copper wires, an array of metal wires like an array of copper
wires, or flexible connection comprising a material with a thermal
conductivity 100 W/(mK) or higher can be used. Such materials could
be aluminum, graphite, silver, copper, brass or the like.
[0036] According to a further embodiment, as shown in FIG. 3, a
braid 364 of a metal, like copper braids or an array of metal
braids 364 like copper braids, braids of a material with a thermal
conductivity of 100 W/(mK) or higher can be used. Such materials
could be aluminum, graphite, silver, copper, brass or the like.
[0037] According to an even further embodiment, as shown in FIG. 4,
the cooling unit 146 and the emitter unit 150 are connected by a
spiral spring thermal conductivity means 464. The spiral heat
conducting means 464 can include a material with a thermal
conductivity 100 W/(mK) or higher. Such materials could be
aluminum, graphite, silver, copper, brass or the like.
[0038] According to even further embodiments, the thermal
conductivity unit can be provided by stripes of flexible material
with a thermal conductivity of, e.g., 100 W/(mK) or higher.
Generally, the thermal conductivity unit should provide the thermal
conductivity between the cooling unit and the emitter unit and
should provide a damping of vibrations to reduce vibration
transfer, as explained with regard to other embodiments.
[0039] According to the embodiment shown in FIG. 1, the cooling
unit 146 has a reduced vibration transfer to the emitter unit 150.
As shown in FIG. 1, further vibrational decoupling from the cooling
unit to the gun chamber is provided by vibration reducing means
162, for example a bellows or the like. According to further
embodiments, which can be combined with any of the embodiments
described herein, also other means for reducing vibrations transfer
from the cooling unit to the charged particle beam column can be
used. As an example, a spring support, rubber parts, or other means
for vibrations isolation can be used to provide a connection
between the cooling unit and the charged particle beam column.
However, according to other embodiments, the cooling unit 146 can
be directly mounted to the charged particle beam column. Thereby,
nevertheless, a transfer of vibrations is also reduced by a thermal
conductivity unit, which is decoupling with regard to vibrations
from the cooling unit to the emitter unit 150.
[0040] Generally, the high resolution gas field ion source charged
particle beam devices allow for an improvement in resolution.
However, the required cooling for gas field ion sources may
introduce vibrations that eliminate high resolution possibilities
of gas field ion sources. In light of the embodiments described
herein, since the necessity to cool the source to cryo-temperatures
is met without transferring the vibrations of the cooling unit to
the emitter unit, an improved gas field ion source can be provided.
According to embodiments described herein, the emitter unit is not
fixed to the cooling unit but rather to the column of the charged
particle beam device. The heat transfer between the emitter and the
cool head is provided by flexible heat conducting means, which
provide a decoupling with regard to vibrations. Thus, the emitter
is mechanically decoupled from the vibrating cooling head and the
mechanical stability of the emitter unit including the emitter tip
is increased.
[0041] FIGS. 5a and 5b show a further embodiment for mechanical
decoupling of a cooling unit 146 and an emitter unit 150. FIG. 5a
shows a side view of the cooling unit 146 and shows protruding
portion 546. According to one embodiment, as shown in FIG. 5a, the
protruding portion 546 of the cooling unit can be provided at the
outer region or the perimeter of the cooling unit 146. The emitter
unit 150 has a protruding portion 556. As shown in FIG. 5a, the
protruding portion 556 of the emitter unit 150 can be provided in
the center or an inner region of the emitter unit 150. The
protruding portion 546 of the cooling unit 146 and the protruding
portion 556 of the emitter unit 150 are thermally connected with
each other by the thermal conductivity unit 564. The thermal
conductivity unit 564 includes a plurality of wires or braids which
are horizontally provided between protruding portions of the
cooling unit and the emitter unit.
[0042] The thermal conductivity unit 564 can typically include one
or more wires or braids, which are provided in a spiral manner from
the outer protrusion to the inner protrusion. Thereby, as an
example, the wires or braids can extend along about 45.degree. to
135.degree..
[0043] According to some embodiments described herein, the
protruding portions of the cooling unit and the protruding portion
of the emitter unit overlap in a first direction. Thereby, the
braid/wire or the braids/wires can be provided to extend in a plane
perpendicular to the first direction. The protruding portions in
combination with the horizontally extending thermal conductivity
units allow reducing the required space in the height
direction.
[0044] As another example, as shown in FIG. 6, the gas field ion
source can optionally be provided as follows. The gas field ion
source 600 includes a cooling unit 146 and an emitter unit 110/140.
According to some embodiments, which can be combined with any of
the embodiments described herein, an emitter module 110 and the
supply module 140 are provided. FIG. 6 shows the supply module and
the emitter module separated by dashed line 10. Between the emitter
module 110 and the supply module 114 a plurality of connections are
provided, which are detachably connectable. Thus, the emitter
module 110 and the supply module 114 can be provided substantially
independent from each other the emitter module is easily
replaceable.
[0045] Cooling to cryo temperatures, high voltage, heating current
and gas can be supplied to the emitter module, whereby a
complicated and difficultly structures that are difficult to
maintain can be omitted. Thus, the replacement of the emitted tip
can be more easily conducted with the modular gas field ion source
100.
[0046] As shown in FIG. 6, an easily replaceable emitter module 110
for the gas field ion source 100 is provided according to
embodiments described herein. Thereby, an emitter structure
includes an emitter 13, e.g., a sharpened single crystal, which is
for example made of tungsten, iridium, or the like and which is
welded to a supporting wire 12. Further, a base 115 is provided.
The supporting wire is fixed to the base 115. According to further
embodiments described herein, the base can include a ceramic
material.
[0047] The emitter module 110 further includes an emitter holder.
According to one embodiment, the emitter holder has a cup-like
structure. For example, it has a circular shape when seen from the
top. The emitter holder 112 may, according to further embodiments,
surround the emitter tip 13 and has, for example, the purpose of
containing the gas for the gas field ion source and supporting the
extraction electrode 114. The extraction electrode 114 acts as a
counter electrode to the positively biased emitter during
operation.
[0048] According to an even further embodiment, the extraction
voltage can be supplied by conductor 116.
[0049] According to one embodiment, as shown in FIG. 6 conductors
122 are embedded in the base 115 and have connections 124, which
provide an electrical contact of the conductor 122 within the base
115 and the conductor 126 within the emitter holder 112. Thereby, a
high-voltage for the gas field ion source and a heating current can
be supplied via the supporting wire 12 to the emitter tip 13.
[0050] The emitter holder 12 further includes a gas conduit 113 for
providing the gas used for the gas field ion source.
[0051] The supply module 140 includes the main body 142. The main
body 142 has a first portion 143 and a second portion of 144.
Generally, high voltage supply conductors 137 and 136 and a gas
conduit 145 are provided.
[0052] According to some embodiments, which can be combined with
any of the embodiments described herein, the high voltage supply
conductors can also be used for providing a heating current to the
emitter. According to alternative embodiments, which can also be
yielded by a combination with any of the embodiments described
herein, heating current conductors can additionally be provided.
According to further embodiments, which can be combined with any of
the embodiments described herein, a thermal conductivity between
the supply module and the emitter module can be provided via any,
or all of the electrical conductors or thermal conduction means can
additionally or alternatively be provided.
[0053] Further, according to one embodiment, the thermal conductor
is provided by the second portion 144. According to an even further
embodiment, the thermal conductor includes an electrical insulator
with a high thermal conductivity, for example, sapphire or the
like.
[0054] According to embodiments described herein, the supply module
140 supplies the functions of cooling, high-voltage, heating
current, and gas supply.
[0055] According to further embodiments, two or more conduits, that
is gas inlets, can be provided. Thereby, a focused ion beam device
further can include an ion beam column including an emitter area
for generating ions, a first gas inlet adapted to introduce a first
gas to the emitter area, a second gas inlet adapted to introduce a
second gas different from the first gas to the emitter area, and a
switching unit adapted to switch between introducing the first gas
and introducing the second gas. According to other embodiments, a
focused ion beam device can be provided, wherein the focused ion
beam device includes an ion beam column including an emitter area
for generating ions, means for switching between introducing a
light gas into the emitter area for an observation mode and
introducing a heavy gas into the emitter area for a modification
mode, wherein the light gas is selected from the group consisting
of hydrogen and helium and the heavy gas has an atomic mass of 10
g/mol or higher. According to yet other embodiments, a method of
operating a focused ion beam device can be provided. The method
includes biasing an emitter within an emitter area wherein ions are
generated, switching between introducing a light gas to the emitter
area and a heavy gas to the emitter area, wherein the light gas is
selected from the group consisting of hydrogen and helium and the
heavy gas has an atomic mass of 10 g/mol or higher. These and other
modifications in order to yield further embodiments are for example
disclosed in commonly assigned and co-pending European application
No. 06026210.2, filed Dec. 18, 2006, entitled "Gas Field ion source
for multiple applications", which is incorporated herein by
reference in its entirety for the purpose of describing
modification to insert two or more gases, that is respective
apparatuses and/or methods.
[0056] In order to provide the modular concept and, additionally an
easy separation substantially along the line 10, both the emitter
module 110 and the supply module 140 include detachably connectable
connections for high-voltage, and gas supply. According to further
embodiments, additional connections for cooling and heating current
can be provided, particularly in the case that the connections for
high-voltage and gas supply do not provide a transfer means for
cooling and heating current. In FIG. 1, the electrical connections
are indicated by reference numbers 131, the thermal conductor
connection is indicated by reference number 133 and the gas supply
connection is indicated by reference number 132. According to other
embodiments, the thermal conductor connection can, additionally or
alternatively, be provided by the electrical connections.
[0057] According to embodiments described herein, the detachably
connectable connections are provided at the interface (see, e.g.,
line 10 in FIGS. 1-4) between the emitter module and the supply
module.
[0058] According to an even further embodiment, which can be
combined with any of the other embodiments described herein, the
emitter module and the supply module are adapted to allow a
separation between or connection of the modules during which the
detachably connectable connection assemblies of the emitter module
and the corresponding detachably connectable connection assemblies
of the supply module are separated or connected, respectively.
Accordingly, the gas field ion source allows for an easy separation
of the emitter module and the supply module. Thereby, maintenance
of the modular gas field ion source can be conducted more
easily.
[0059] According to one embodiment, the installation of the emitter
module, which is to be replaced during regular maintenance, can be
done by pressing the detachably connectable electrical connectors
of the emitter module into a bushing in the supply module. However,
according to further embodiments, connection methods like fixing
screws or a concentric screw-nut are also possible. Thereby, all
supplies for operating the gas field ion source are connected.
[0060] According to embodiments described herein, the emitter
structure including the ceramic base 115, the supporting wire 12
and the emitter tip 13 may advantageously be similar to emitters
structures used for cold field electron emission (CFE). Thereby,
easily available emitter structures, which have previously been
used, can be provided for the modular gas field ion source.
Maintenance of a modular gas field ion source microscope can,
therefore, be made even easier.
[0061] The emitter structure can, according to specific
embodiments, be fixed to the emitter holder 112 by screws, or the
like. Thereby, according to even further embodiments, an alignment
of the emitter structure (115, 12, 13) and the emitter holder 112
may optionally be provided.
[0062] The emitter module 110 which is formed thereby can be
connected to the supply module 140. Thereby, according to
embodiments described herein, within one step, electrical
connections, gas connections and cooling are provided.
[0063] According to an alternative embodiment, which can be
combined with other embodiments described herein, loosening of one
or more of the connection assemblies or opening of fasteners for
one or more of the connection assemblies can additionally be
conducted. However, the emitter module can be removed from or are
placed at the supply module such that the detachably connectable
connections assemblies are connected or at least in position for
fastening the connections.
[0064] As described above, during maintenance, an emitter module
can be removed from the gas field ion source in one piece and a new
emitter module can be placed in the gas field ion source in one
piece. Thereby, all connections are provided and/or ready for being
locked. Further, according to other embodiments, the emitter
structure may be placed in the emitter module before the emitter
module is placed in the gas field ion source. Thereby, an alignment
of the emitter structure and, thereby the emitter can optionally be
provided. According to an even further embodiment, the emitter
module is provided in an aligned position in the gas field ion
source, that is, adjacent to the supply module or can be aligned
after connecting the emitter module and the supply module.
[0065] The embodiments, which are described above with respect to
FIG. 6 allow an easy separation between the supply module and the
emitter module. As described with respect to FIGS. 1 to 5, a
cooling unit 146 may introduce vibrations to the emitter. This is
also true for the embodiments in which the emitter unit is divided
into a supply module and an emitter module. Thus, the cooling unit
should be mechanically decoupled from the emitter unit.
[0066] Accordingly, the cooling unit 146 and the emitter unit
110/140, which are shown in FIG. 6, are connected with each other
by an array of braids 664. The braids provide a thermal
conductivity without transfer of vibrations. According to further
embodiments, the modular emitter unit, which is described above,
con be combined with any of the other embodiments described
herein.
[0067] FIG. 7 shows a further embodiment of a charged particle beam
device 700. The charged particle beam device 700 includes a column
with a gun chamber 21 and a further chamber 24. Within the gun
chamber 21 the emitter unit 150 including the emitter 152 is
provided. The emitter unit 150 is connected to an upper portion of
the gun chamber 21 and, therefore the charged particle beam column
by a holder, which is an emitter unit support 155. The charged
particle beam device 100 further includes a cooling unit 146 which
is connected to the charged particle beam column with a
mechanically decoupling connection means 162.
[0068] According to one embodiment a bellows or the like can be
used for connecting the cooling unit 146 to the charged particle
beam column. FIG. 7 shows a thermal conductivity unit 764 which
provides thermal conductivity between the cooling unit 146 and the
emitter unit 150. The thermal conductivity unit 764 can be,
according to one embodiment, a space filled with a thermally
conductive gas such as helium or the like. Thereby, the vibrations
from the cooling unit 146 are decoupled from the emitter unit 150
and the thermal conductivity is still provided by the thermally
conductive gas. According to even further embodiments, the emitter
unit can be provided according to any of the embodiments described
above.
[0069] FIG. 8 shows a charged particle beam device 800. The ion
beam device includes a column 20. Therein a gas field ion source
810 according to any of the embodiments described herein can be
provided. The primary beam is emitted essentially along optical
axis 2. The gun chamber housing 21 is separated by aperture 33 from
the following chamber 22. The primary ion beam is formed and guided
by condenser lens 42.
[0070] The primary ion beam passes through the opening 12 in
detector 40 and is focused by objective lens 30 on the specimen 5,
which located on the specimen holder 50. Secondary and/or
backscattered particles, which are released on impingement of the
primary ion beam, can be detected by detector 40 for image
generation. The emitter unit 810 is connected to the gun chamber
housing and, thus, the column 20 via holder 55. The cooling unit is
connected to the column 20. Thereby, no direct vibration transfer
connection between the cooling unit 146 and the emitter unit 810 is
provided. The thermal conductivity between the cooling unit 146 and
the emitter is provided by thermal conductivity unit 864, which
transfers heat while mechanically decoupling the cooling unit and
the emitter unit in order to reduce transfer of vibrations from the
cooling unit to the emitter.
[0071] According to embodiments described herein a gas field ion
source for a charged particle beam device having a charged particle
beam column can be provided. The gas field ion source includes an
emitter unit, a cooling unit, and a thermal conductivity unit for
thermal conductivity from the cooling unit to the emitter unit,
wherein the thermal conductivity unit is adapted for reduction of
vibration transfer from the cooling unit to the emitter unit.
[0072] Generally, for embodiment described herein, a reduced
transfer of vibrations can also be considered an increased
vibration isolation. According to different embodiments, vibrations
from the cooling unit can be damped or reduced by a thermal
conductivity unit by at least a factor of 10, a factor of 30 or
even a factor of 100.
[0073] According to further embodiments, an emitter unit support
for connecting the emitter unit with a portion of the charged
particle beam column can be provided. Typically, the emitter unit
support connects the emitter unit to the portion of the charged
particle beam column such that the connecting means excludes a
connection with or via the cooling unit. According to yet further
embodiments, it is possible that the thermal conductivity unit
includes a flexible wire or braid. Optionally, the flexible wire or
braid can consist of a material with a thermal conductivity of 100
W/(mK) or higher. Additionally or alternatively the flexible wire
or braid includes at least one material selected from the group
consisting of: copper, aluminum, brass, silver, and a combination
thereof.
[0074] According to yet further embodiments, the wire or braid of
the thermal conductivity unit includes can extend between a
protruding portion of the cooling unit and a protruding portion of
the emitter unit. Thereby, it is typically possible that the wire
or braid extends horizontally. According to even further
embodiments, the thermal conductivity unit can include a gas filled
space.
[0075] According to even further embodiments, the gas field ion
source can include: an emitter module having an emitter holder, an
emitter structure, a detachably connectable electrical connection
assembly of the emitter module, and detachably connectable gas
supply connection assembly of the emitter module. The gas field ion
source can further include supply module having at least one
electrical conductor for providing voltage and/or current, a gas
supply conduit, a thermal conductor, a detachably connectable
electrical connection assembly of the supply module, and a
detachably connectable gas supply connection assembly of the supply
module, wherein the emitter module and the supply module are
detachably connectable by the detachably connectable connection
assemblies of the emitter module and the detachably connectable
connection assemblies of the supply module. Additionally, the
emitter module can further include a detachably connectable thermal
conductivity connection assembly of the emitter module and a
detachably connectable thermal conductivity connection assembly of
the supply module;
[0076] According to yet further embodiments, a charged particle
beam device can be provided, which includes a gas field ion source
according to any of the embodiments described herein.
[0077] According to yet further embodiments, methods of
manufacturing a charged particle beam device having a charged
particle beam column and a gas field ion source with an emitter
unit and a cooling unit are provided. The methods can include
mounting the emitter unit and the cooling unit mechanically
decoupled from each other to the charge particle beam column, and
providing a mechanically decoupling thermal conductivity unit
between the emitter unit and the cooling unit.
[0078] While the foregoing is directed to embodiments of the
invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
* * * * *