U.S. patent application number 11/215985 was filed with the patent office on 2006-01-05 for nano-structure and method of fabricating nano-structures.
Invention is credited to Pavel Kornilovich, Vincent C. Korthuis, Peter Mardilovich, Sriram Ramamoorthi.
Application Number | 20060003267 11/215985 |
Document ID | / |
Family ID | 35054750 |
Filed Date | 2006-01-05 |
United States Patent
Application |
20060003267 |
Kind Code |
A1 |
Ramamoorthi; Sriram ; et
al. |
January 5, 2006 |
Nano-structure and method of fabricating nano-structures
Abstract
In one embodiment, a method for fabricating a nano-structure
includes forming a feature on a substrate, depositing multiple
layers of material over the substrate and feature to form a
multi-layer stack, depositing a film over the multi-layer stack,
removing a portion of the film and the multi-layer stack to expose
edges of the layers of material, and removing portions of the
layers of material to form trenches at a surface of the
nano-structure.
Inventors: |
Ramamoorthi; Sriram;
(Corvallis, OR) ; Mardilovich; Peter; (Corvallis,
OR) ; Kornilovich; Pavel; (Corvallis, OR) ;
Korthuis; Vincent C.; (Corvallis, OR) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD
INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Family ID: |
35054750 |
Appl. No.: |
11/215985 |
Filed: |
August 31, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10817729 |
Apr 2, 2004 |
|
|
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11215985 |
Aug 31, 2005 |
|
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Current U.S.
Class: |
430/322 ;
257/E21.582 |
Current CPC
Class: |
H05K 2203/0117 20130101;
G03F 7/40 20130101; H01L 21/76838 20130101; H05K 3/205 20130101;
H05K 3/20 20130101; C30B 29/68 20130101; H05K 2203/025 20130101;
C23C 4/18 20130101; C23C 4/123 20160101; H01L 21/4846 20130101 |
Class at
Publication: |
430/322 |
International
Class: |
G03C 5/00 20060101
G03C005/00 |
Claims
1. A nano-structure, comprising: a substrate; a feature formed on
the substrate that extends upwardly from a surface of the
substrate; layers of material that overlie the substrate surface
and at least a portion of the feature; and an exposed surface
comprising a top surface of the feature and edges of the layers of
material; wherein portions of selected layers of material have been
etched away to form trenches adjacent the top surface of the top
surface of the feature.
2. The nano-structure of claim 1, wherein the feature has a
trapezoidal cross-section.
3. The nano-structure of claim 1, wherein the feature has a width
adjacent the substrate surface of approximately 250 nanometers to
approximately 100 microns.
4. The nano-structure of claim 1, wherein the layers of material
comprise at least two different types of material.
5. The nano-structure of claim 4, wherein layers of different
material are formed in an alternating arrangement.
6. The nano-structure of claim 5, wherein only the layers of one
type of material have been etched away to form the trenches.
7. The nano-structure of claim 1, wherein each layer of material
has a thickness of approximately 10 Angstroms to approximately 1000
Angstroms.
8. The nano-structure of claim 1, further comprising a
planarization film adjacent the edges that overlies a portion of
the layers of material.
9. The nano-structure of claim 8, wherein the planarization film is
composed of silicon oxide.
10. The nano-structure of claim 1, wherein the trenches comprise
opposed side walls and a base.
11. The nano-structure of claim 10, wherein the opposed side walls
are formed from a first material and the base is formed of a second
material.
12. The nano-structure of claim 1, wherein the trenches are
oriented in an oblique direction relative to the exposed
surface.
13. The nano-structure of claim 1, wherein the nano-structure is a
nano-imprint stamp.
14. A method for fabricating a nano-structure, the method
comprising: forming a feature on a substrate; depositing multiple
layers of material over the substrate and feature to form a
multi-layer stack; depositing a film over the multi-layer stack;
removing a portion of the film and the multi-layer stack to expose
edges of the layers of material; and removing portions of the
layers of material to form trenches at a surface of the
nano-structure.
15. The method of claim 14, wherein forming a feature comprises
forming a dielectric bump on the substrate.
16. The method of claim 15, wherein the dielectric bump has a
trapezoidal cross-section.
17. The method of claim 15, wherein the dielectric bump has a width
adjacent a surface of the substrate of approximately 250 nanometers
to approximately 100 microns.
18. The method of claim 14, wherein depositing multiple layers of
material comprises depositing at least two different materials in
an alternating arrangement such that the multi-layer stack
comprises alternating layers of material.
19. The method of claim 14, wherein depositing a film comprises
depositing a film over the multi-layer stack having a height that
exceeds the top of the multi-layer stack.
20. The method of claim 19, wherein removing a portion of the film
and the multi-layer stack comprises planarizing the film and the
multi-layer stack together to form the surface of the
nano-structure and the edges.
21. The method of claim 14, wherein removing portions of the layers
comprises etching away portions of selected layers to form the
trenches.
22. The method of claim 21, wherein etching away portions of
selected layers comprises etching away layers of a first type of
material without etching away layers of a second type of
material.
23. The method of claim 21, wherein the method comprises a method
for fabricating a nano-imprint stamp.
24. A method for fabricating a nano-structure, the method
comprising: forming a dielectric bump on a surface of a substrate,
the feature having opposed sides, at least one of the sides
extending in an oblique direction from the substrate surface;
depositing multiple layers of at least two different materials in
an alternating manner over the substrate surface and the dielectric
bump to form a multi-layer stack of alternating materials;
depositing a film over the multi-layer stack such that the
multi-layer stack is completely covered by the film; planarizing
the film and the multi-layer stack to form a surface that comprises
exposed edges of the layers of material; and etching away layers of
one of the materials to form trenches in the formed surface, the
trenches extending in an oblique direction relative to the formed
surface.
25. The method of claim 24, wherein the dielectric bump has a
trapezoidal cross-section.
26. The method of claim 24, wherein the dielectric bump has a width
adjacent a surface of the substrate of approximately 250 nanometers
to approximately 100 microns.
27. The method of claim 24, wherein the method comprises a method
for fabricating a nano-imprint stamp.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of copending U.S.
utility application entitled, "Fabrication and Use of
Superlattice," having Ser. No. 10/817,729, filed Apr. 2, 2004,
which is entirely incorporated herein by reference.
BACKGROUND
[0002] Although fabrication of structures on a "nano" scale has
been practiced for several years, there are still many challenges
that are to be overcome to enable manufacture of desired
structures.
[0003] For instance, problems can be encountered when a
nano-structure is formed that includes a plurality layers of
material that are to be planarized. Such problems may include, for
example, fraying, delamination, erosion, dishing, and rounding.
[0004] Desired is a method for forming nano-structures that
overcome or reduce such problems.
SUMMARY
[0005] In one embodiment, a nano-structure comprises a substrate, a
feature formed on the substrate that extends upwardly from a
surface of the substrate, layers of material that overlie the
substrate surface and at least a portion of the feature, and an
exposed surface comprising a top surface of the feature and edges
of the layers of material, wherein portions of selected layers of
material have been etched away to form trenches adjacent the top
surface of the top surface of the feature.
[0006] In one embodiment, a method for fabricating a nano-structure
comprises forming a feature on a substrate, depositing multiple
layers of material over the substrate and feature to form a
multi-layer stack, depositing a film over the multi-layer stack,
removing a portion of the film and the multi-layer stack to expose
edges of the layers of material, and removing portions of the
layers of material to form trenches at a surface of the
nano-structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The disclosed nano-structure and method can be better
understood with reference to the following drawings. The components
in the drawings are not necessarily to scale.
[0008] FIG. 1 is an end view of an embodiment of a nano-structure
in an initial stage of fabrication.
[0009] FIG. 2 is a top perspective view of the nano-structure shown
in FIG. 1.
[0010] FIG. 3 is an end view of the nano-structure of FIG. 1 in a
later stage of fabrication.
[0011] FIG. 4 is an end view of the nano-structure of FIG. 1 in yet
a later stage of fabrication.
[0012] FIG. 5 is an end view the nano-structure of FIG. 1 in yet
another later stage of fabrication.
[0013] FIG. 6 is an end view of an embodiment of a completed
nano-structure.
[0014] FIG. 7 is a detail view of trenches formed in the
nano-structure of FIG. 6.
[0015] FIG. 8 is a flow diagram of an embodiment of a method for
fabricating a nano-structure.
DETAILED DESCRIPTION
[0016] Disclosed is a nano-structure and a method for fabricating
nano-structures. According to at least one embodiment of the
method, multiple layers of material that overlie a feature that is
formed on the surface of a substrate are covered by a sacrificial
film that enables planarization of the multiple layers while
reducing or preventing one or more of fraying, delamination,
erosion, dishing, and rounding.
[0017] Referring now in more detail to the drawings, in which like
numerals indicate corresponding parts throughout the several views,
FIG. 1 illustrates an embodiment of a nano-structure 100 in an
initial stage of fabrication. As is indicated in FIG. 1, the
nano-structure 100 includes a substrate 102 that, for example,
comprises a silicon wafer. Formed on a surface 104 of the substrate
102 is a feature 106 that, in the embodiment shown in FIG. 1,
comprises a dielectric bump. The bump 106 can be composed of
silicon oxide and can be formed using any one of various
fabrication methods. For example, the bump 106 can be formed by
depositing a layer of silicon oxide (not shown), and etching the
silicon oxide away to leave a bump having the general shape and
configuration illustrated in FIG. 1.
[0018] In this embodiment, the bump 106 has a trapezoidal
cross-section that is defined by a base 108, opposed sides 110, and
a top 112. As is apparent from FIG. 1, the base 108 is larger than
the top 112, and the opposed sides 110 extend diagonally or
obliquely toward each other from the base to the top. As is shown
in FIG. 2, the bump 106 is elongated (as compared to the sides 110
and top 112) so as to extend a relatively long distance across the
surface 104 of the substrate 102. Although the feature 106 formed
on the substrate 102 is described and illustrated as comprising a
bump having a trapezoidal cross-section, other configurations and
shapes are possible.
[0019] As is described above, the nano-structure 100 is constructed
on a nano-scale. By way of example, the bump 106 has a height
dimension, h, that ranges from approximately 200 nanometers (nm) to
approximately 5000 nm, and a width dimension, w, that ranges from
approximately 250 nm to 100 microns (.mu.m). In one embodiment, the
bump 106 has a height of approximately 2500 nm and a width of
approximately 5000 nm.
[0020] It is noted that, although the feature has been illustrated
and described as a bump, the feature could take substantially any
other form including, for example, a step. Moreover, although
specific example dimensions have been described, those dimensions
are only examples, and the feature could have other dimensions,
which may only be limited by the size of the substrate.
[0021] Referring next to FIGS. 3-6, various other steps of the
fabrication of the nano-structure 100 will be described. Beginning
with FIG. 3, multiple overlapping layers 114 of material (e.g.,
metal) are deposited over the substrate 102 and the bump 106 to
form a multi-layered stack 116 of material having opposed comers
118. When more than one type of material is used to form the layers
114, such as two types of material, the layers can alternate
between the types of material. For instance, a first layer of gold
can be deposited, followed by a layer of tantalum, followed by a
further layer of gold, followed by a further layer of tantalum,
etc., until a desired number of alternating layers 114 of material
have been deposited. Depending on the material, such deposition can
be achieved using chemical vapor deposition (CVD), physical vapor
deposition (PVD), atomic layer deposition (ALD), or another
process. Notably, other types of materials can be used to form the
layers 114. Example alternative materials include titanium nitride,
silicon, silicon oxide, and metal oxides.
[0022] In the embodiment shown in the figures, nine layers 114 of
material have been deposited. By way of example, each layer 114 is
approximately 10 Angstoms (.ANG.) to approximately 1000 .ANG.
thick. For instance, in one embodiment, each layer 114 can be
approximately 500 .ANG. thick.
[0023] With the structure illustrated in FIG. 3, multiple trenches,
which are useful for nano-imprinting (for example), can be formed
by planarizing the layers 114 above the bump 106 to yield a bump
that has multiple layers of material along both sides of its
length. Assuming an alternating arrangement of materials such as
that described above, multiple trenches can be formed by etching
away one of the materials (i.e., multiple layers of that material),
leaving trenches defined by the layers of material that were not
etched away. Unfortunately, such planarization often results in one
or more of fraying, delamination, erosion, dishing, and rounding
using known techniques.
[0024] To avoid such problems, a sacrificial or planarizing film
120 of material is deposited over the multiple layers 114 prior to
planarization, as is shown in FIG. 4. By way of example, the
planarizing film 120 comprises a thick layer of silicon oxide.
Examples of other materials that can be used for the planarizing
film. 120 include amorphous silicon and spin-on-glass. Regardless
of the particular material that is used, the planarizing film 120
has a thickness that will result in a film height that equals or
exceeds the height of the multi-layered stack 116 (see FIG. 4).
With such a configuration, the low-topography points of the
structure 100 are brought above the bump 106 and the multi-layered
stack 116 that has been deposited thereon. This enables a non-zero
removal rate of the low points to be above the height of the
multi-layered stack 116. In some embodiments, the planarizing film
120 has a thickness of approximately 200 nm to approximately 10
.mu.m. For example, the film 120 can be approximately 2.5 micons
(.mu.m) thick.
[0025] At this point, the planarizing film 120 and the top of the
multi-layered stack 116 can be removed. Specifically, as is
indicated in FIG. 5, the film 120 and top of the stack 116 are
removed, for example using a chemical-mechanical planarization
(CMP) process, such that the top portion of the bump 106 is
exposed. Alternatively, mechanical or chemical-mechanical polishing
can be used to achieve this result. As is indicated in FIG. 5,
little or no fraying, delamination, erosion, or dishing has
occurred. In addition, the comers 118 of the multi-layered stack
116 are minimized due to the provision of the planarizing film
120.
[0026] At this point, multiple trenches can be formed in the new
surface 122, and the exposed edges of the stacked layers 114, that
results from the planarization process. Referring to FIG. 6,
trenches 124 can be formed by etching one or more of the layers 114
of material of the multi-layer stack 116. For instance, in cases in
which the stack 116 is composed of alternating materials, one of
the materials (and therefore multiple layers 114) can be
selectively etched away to produce trenches 124 that are defined by
the remaining layers. To cite a specific example, when alternating
layers of tantalum and gold are deposited, a portion of the gold
layers can be etched away to define the trenches 124. FIG. 7
illustrates such an embodiment in detail. As is shown in that
figure, the tantalum layers (Ta) remain intact and extend to the
surface 122, while the gold layers (Au) have been etched away to
define the trenches 124. As is further shown in the figure, the
trenches 124 are defined by side walls 126 (e.g., of tantalum) and
bases 128 (e.g., of gold). The trenches 124 have widths equal to
the thickness of the layers (in this example gold layers) that have
been etched away.
[0027] The structure that results from the above-described
fabrication is a comb-like structure in which diagonal or oblique
trenches 124 are formed in the surface of the nano-structure 100.
In particular, multiple parallel, oblique trenches 124 are formed
on both sides of the bump 106 such that the trenches are angled
toward each other as they are traversed upward from the bases 126
to the surface 122. By way of example, each trench 124 forms an
angle, .alpha., of approximately 30 to approximately 90 degrees
relative to the surface 122 (see FIG. 7). As is mentioned above,
the structure 100 can, for example, be used for nano-imprinting. In
such a case, the nano-structure 100 may be considered to be a
nano-imprinting structure.
[0028] An embodiment of a method for fabricating a nano-structure
can be summarized as provided in FIG. 8. Beginning with block 800,
a feature, such as a dielectric bump, is formed on a substrate. The
feature can be formed by, for instance, depositing a layer of
material on top of the substrate, and etching away a portion of the
deposited layer. Next, multiple layers of material are deposited
over the substrate and feature to form a multi-layer stack, as
indicated in block 802. By way of example, two or more different
types of materials are deposited in an alternating fashion.
[0029] Referring next to block 804, a sacrificial film is deposited
over the multi-layer stack such that the height of the film equals
or exceeds the height of the multi-layer stack, including the
portion of the stack that overlies the feature. Once the film has
been deposited, a portion of the film and the stack is removed, as
indicated in block 806, for example using a planarization
process.
[0030] Finally, as is indicated in block 808, portions of various
layers of the multi-layer stack are removed to form trenches in a
surface that results when the portion of the film and stack are
removed (in block 806). By way of example, the portions of the
layers can be removed using a selective etching process.
* * * * *