U.S. patent application number 11/679179 was filed with the patent office on 2008-01-03 for fin mask and method for fabricating saddle type fin using the same.
This patent application is currently assigned to Hynix Semiconductor Inc.. Invention is credited to Kwang-Ok Kim.
Application Number | 20080003833 11/679179 |
Document ID | / |
Family ID | 38877251 |
Filed Date | 2008-01-03 |
United States Patent
Application |
20080003833 |
Kind Code |
A1 |
Kim; Kwang-Ok |
January 3, 2008 |
FIN MASK AND METHOD FOR FABRICATING SADDLE TYPE FIN USING THE
SAME
Abstract
A fin mask for forming saddle type fins in each of active
regions formed in an island shape having a certain size with a
major axis and a minor axis includes a first fin mask of a line
type, and a second fin mask of an island type, wherein the first
fin mask and the second fin mask in combination expose saddle type
fin regions and cover ends of the neighboring active regions along
the major axis.
Inventors: |
Kim; Kwang-Ok; (Ichon-shi,
KR) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER, EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Hynix Semiconductor Inc.
Icheon-si
KR
|
Family ID: |
38877251 |
Appl. No.: |
11/679179 |
Filed: |
February 26, 2007 |
Current U.S.
Class: |
438/703 ; 216/51;
257/E21.409; 257/E21.655; 257/E27.084 |
Current CPC
Class: |
H01L 27/0207 20130101;
H01L 29/7851 20130101; H01L 27/10879 20130101; H01L 27/10876
20130101; H01L 29/66795 20130101 |
Class at
Publication: |
438/703 ; 216/51;
257/E21.409; 257/E27.084 |
International
Class: |
H01L 21/336 20060101
H01L021/336; H01L 27/108 20060101 H01L027/108 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2006 |
KR |
10-2006-0061437 |
Dec 15, 2006 |
KR |
10-2006-0128839 |
Claims
1. A fin mask for forming saddle type fins in each of active
regions formed in an island shape having a certain size with a
major axis and a minor axis, the fin mask comprising: a first fin
mask of a line type; and a second fin mask of an island type,
wherein the first fin mask and the second fin mask in combination
expose saddle type fin regions and cover ends of the neighboring
active regions along the major axis.
2. The fin mask of claim 1, wherein the second fin mask has a
rectangular shape overlapping the first fin mask.
3. The fin mask of claim 1, wherein the second fin mask is formed
in a rectangular shape overlapping the first fin mask, wherein
portions of the second fin mask covering the ends of the active
regions along the major axis have a larger surface area than the
ends of the active regions.
4. The fin mask of claim 3, wherein the portions of the second fin
mask covering the ends of the active regions along the major axis
are formed in a ball or an ellipse shape.
5. A fin mask for forming saddle type fins in each of active
regions formed in an island shape having a certain size with a
major axis and a minor axis, the fin mask comprising: a first fin
mask of a line type; and a second fin mask having openings, wherein
the first fin mask and the second fin mask in combination expose
saddle type fin regions and cover ends of the neighboring active
regions along the major axis.
6. The fin mask of claim 5, wherein the openings of the second fin
mask are formed in an island shape, wherein the island shape
includes a jigsaw puzzle shape.
7. A fin mask for forming saddle type fins in each of active
regions formed in an island shape having a certain size with a
major axis and a minor axis, the fin mask comprising island-shaped
openings exposing saddle type fin regions and covering the rest of
the active regions.
8. The fin mask of claim 7, wherein the openings are formed in a
rectangular or an ellipse shape.
9. A method for fabricating a saddle type fin, the method
comprising: providing a substrate defining at least two active
regions that have neighboring ends in a major axis; forming an etch
barrier pattern over the substrate, the etch barrier pattern
exposing saddle type fin regions of the active regions and covering
the rest of the active regions; and etching the saddle type fin
regions to form saddle type fins in a local damascene structure,
wherein forming the etch barrier pattern comprises forming a first
fin mask and a second fin mask, and wherein the first fin mask
exposes the saddle type fin regions in a line pattern and the
second fin mask covers the neighboring ends of the active
regions.
10. The method of claim 9, wherein the first fin mask is a line
type and the second fin mask is an island type, the second fin mask
being formed after the first fin mask is removed.
11. The method of claim 10, wherein the second fin mask is formed
in an island pattern comprising a rectangular shape overlapping the
first fin mask, wherein portions of the second fin mask covering
the ends of the active regions have a larger surface area than the
ends of the active regions.
12. The method of claim 11, wherein the portions of the second fin
mask covering the ends of the active regions have a round
shape.
13. The method of claim 10, wherein the etch barrier pattern formed
by the first and second fin masks in combination comprises an
amorphous carbon pattern.
14. The method of claim 13, wherein forming the amorphous carbon
pattern comprises: forming an amorphous carbon layer; forming a
dielectric anti-reflective coating (DARC) layer over the amorphous
carbon layer; forming a polysilicon layer over the DARC layer;
etching the polysilicon layer using the first fin mask; etching the
DARC layer using the second fin mask; and etching the amorphous
carbon layer using the DARC layer.
15. The method of claim 13, wherein forming the amorphous carbon
pattern comprises: forming an amorphous carbon layer; forming a
dielectric anti-reflective coating (DARC) layer over the amorphous
carbon layer; forming a polysilicon layer over the DARC layer;
etching the polysilicon layer using the second fin mask; etching
the DARC layer using the first fin mask; and etching the amorphous
carbon layer using the DARC layer.
16. The method of claim 9, wherein forming the etch barrier pattern
comprises forming a first fin mask and a second fin mask in
combination, wherein the first fin mask exposes the saddle type fin
regions in a line shape and the second fin mask exposes the saddle
type fin regions in an island pattern comprising a jigsaw puzzle
shape and covers the neighboring ends of the active regions.
17. The method of claim 16, wherein the etch barrier pattern formed
by the first and second fin masks in combination comprises an
amorphous carbon pattern.
18. The method of claim 17, wherein forming the amorphous carbon
pattern comprises: forming an amorphous carbon layer; forming a
dielectric anti-reflective coating (DARC) layer over the amorphous
carbon layer; forming a polysilicon layer over the DARC layer;
etching the polysilicon layer using the first fin mask; etching the
DARC layer using the second fin mask; and etching the amorphous
carbon layer using the DARC layer.
19. The method of claim 17, wherein forming the amorphous carbon
pattern comprises: forming an amorphous carbon layer; forming a
dielectric anti-reflective coating (DARC) layer over the amorphous
carbon layer; forming a polysilicon layer over the DARC layer;
etching the polysilicon layer using the second fin mask; etching
the DARC layer using the first fin mask; and etching the amorphous
carbon layer using the DARC layer.
20. The method of claim 9, wherein forming the etch barrier pattern
comprises using a fin mask having openings exposing the saddle type
fins and covering the rest regions.
21. The method of claim 20, wherein the openings are formed in a
rectangular or an ellipse shape.
22. The method of claim 20, wherein the etch barrier pattern
comprises an amorphous carbon pattern or a polysilicon pattern.
23. The method of claim 22, wherein forming the amorphous carbon
pattern comprises: forming an amorphous carbon layer; forming a
dielectric anti-reflective coating (DARC) layer over the amorphous
carbon layer; etching the DARC layer using the fin mask; and
etching the amorphous carbon layer using the DARC layer.
24. The method of claim 22, wherein forming the polysilicon pattern
comprises: forming a polysilicon layer; forming a dielectric
anti-reflective coating (DARC) layer over the polysilicon layer;
etching the DARC layer using the fin mask; and etching the
polysilicon layer using the DARC layer.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present invention claims priority of Korean patent
application numbers 10-2006-0061437 and 10-2006-0128839, filed on
Jun. 30, 2006 and Dec. 15, 2006, respectively, which are
incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a method for fabricating a
semiconductor device, and more particularly, to a method for
fabricating a saddle type transistor having a saddle type fin.
[0003] A typical cell in a three-dimensional structure for use in a
dynamic random access memory (DRAM) cell includes a fin structure,
a recess channel structure, and a saddle type structure. The saddle
type structure includes the fin structure and the recess channel
structure in combination.
[0004] FIG. 1A illustrates a perspective view showing a method for
fabricating a typical saddle type transistor, and FIG. 1B
illustrates a plan view of a fin mask. Referring to FIGS. 1A and
1B, an isolation structure 12 is formed in a substrate 11 using a
shallow trench isolation (STI) process. Thus, an active region 11A
having a major axis and a minor axis is defined. A fin mask 13 is
formed over the substrate structure. Saddle type fins 14 are formed
by etching using the fin mask 13. The etching for forming the
saddle type fins 14 may include etching the isolation structure 12
using the fin mask 13 and then etching the active region 11A, or
etching the active region 11A and then etching the isolation
structure 12. The fin mask 13 is removed, and although not
illustrated, a gate oxide layer, a gate electrode, and source/drain
are formed to complete a saddle type transistor.
[0005] The typical method as described above uses the line type fin
mask 13 to form the saddle type fins 14. However, in the typical
method, the active region 11A is exposed by the line type fin mask
13 at regions predetermined for forming the saddle type fins 14 as
well as at the ends of the active region 11A along the major axis.
Thus, dummy saddle type fins 14A may be formed. The dummy saddle
type fins 14A may be formed in an active region that will be
connected to a storage node. Thus, leakage of the storage node and
capacitance of the gate may be increased, deteriorating performance
of the transistor.
SUMMARY OF THE INVENTION
[0006] Embodiments of the present invention are directed towards
providing a fin mask and a method for fabricating a saddle type fin
using the same, which can reduce formation of undesired dummy
saddle type fins at the end of an active region along a major
axis.
[0007] In accordance with an aspect of the present invention, there
is provided a fin mask for forming saddle type fins in each of
active regions formed in an island shape having a certain size with
a major axis and a minor axis, the fin mask including: a first fin
mask of a line type; and a second fin mask of an island type,
wherein the first fin mask and the second fin mask in combination
expose saddle type fin regions and cover ends of the neighboring
active regions along the major axis.
[0008] In accordance with another aspect of the present invention,
there is provided a fin mask for forming saddle type fins in each
of active regions formed in an island shape having a certain size
with a major axis and a minor axis, the fin mask including: a first
fin mask of a line type; and a second fin mask having openings,
wherein the first fin mask and the second fin mask in combination
expose saddle type fin regions and cover ends of the neighboring
active regions along the major axis.
[0009] In accordance with a still another aspect of the present
invention, there is provided a fin mask for forming saddle type
fins in each of active regions formed in an island shape having a
certain size with a major axis and a minor axis, the fin mask
including island-shaped openings exposing saddle type fin regions
and covering the rest of the active regions.
[0010] In accordance with a further aspect of the present
invention, there is provided a method for fabricating a saddle type
fin, including: providing a substrate defining at least two active
regions that have neighboring ends in a major axis; forming an etch
barrier pattern over the substrate, the etch barrier pattern
exposing saddle type fin regions of the active regions and covering
the rest of the active regions; and etching the saddle type fin
regions to form saddle type fins in a local damascene structure,
wherein forming the etch barrier pattern includes forming a first
fin mask and a second fin mask, and wherein the first fin mask
exposes the saddle type fin regions in a line pattern and the
second fin mask covers the neighboring ends of the active
regions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A illustrates a perspective view of a typical method
for fabricating a saddle type fin.
[0012] FIG. 1B illustrates a plan view of a typical fin mask.
[0013] FIG. 2 illustrates a plan view of a fin mask combination
used in fabricating a saddle type fin according to a first
embodiment of the present invention.
[0014] FIGS. 3A to 3E illustrate cross-sectional views of a method
for fabricating a saddle type fin according to the first embodiment
of the present invention.
[0015] FIG. 4 illustrates resultant saddle type fins according to
the first embodiment of the present invention.
[0016] FIG. 5A illustrates a plan view of a fin mask combination
used in fabricating a saddle type fin according to a second
embodiment of the present invention.
[0017] FIG. 5B illustrates a scanning electron microscopic (SEM)
view of a second fin mask according to the second embodiment of the
present invention.
[0018] FIG. 6A illustrates a plan view of a fin mask combination
used in fabricating a saddle type fin according to a third
embodiment of the present invention.
[0019] FIG. 6B illustrates a SEM view of a second fin mask shown in
FIG. 6A.
[0020] FIG. 7A illustrates a plan view of a fin mask used in
fabricating a saddle type fin according to a fourth embodiment of
the present invention.
[0021] FIG. 7B illustrates a SEM view of a fin mask shown in FIG.
7A.
[0022] FIG. 8 illustrates a SEM view of saddle type fins according
to embodiments of the present invention.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0023] The present invention relates to a fin mask and a method for
fabricating a saddle type fin using the same. Formation of dummy
saddle type fins at the ends of neighboring active regions along a
major axis may be reduced through using a fin mask combination that
locally opens saddle type fin regions. Thus, leakage of the storage
node and increased gate capacitance caused by the dummy saddle type
fins may be reduced.
[0024] FIG. 2 illustrates a plan view of a fin mask combination
used in fabricating a saddle type fin according to a first
embodiment of the present invention. A plurality of active regions
101 are formed in a substrate. The substrate has a flat surface
with an X axis and a Y axis. The active regions 101 are formed in a
certain size with a major axis and a minor axis. The active regions
101 are disposed in a manner that ends 104 along the major axis of
two neighboring active regions 101 along the X axis are adjacent to
each other, and an isolation structure 102 is formed between the
adjacent active regions 101. Hereinafter, only one set of elements
are described for convenience.
[0025] The active region 101 is defined by the isolation structure
102. Forming a fin mask according to the first embodiment includes
using a first fin mask FM1 and a second fin mask FM2 in combination
to form saddle type fins 103. The active region 101 and the
isolation structure 102 are selectively etched to form the saddle
type fins 103, that is, the active region 101 protruding in a
saddle type structure. In the present embodiment, the first fin
mask FM1 and the second fin mask FM2 may be sequentially used
according to a given order, and the given order may be changeable.
For instance, the first fin mask FM1 may be formed first and the
second fin mask FM2 may be formed after the first fin mask FM1 is
removed. On the other hand, the second fin mask FM2 may be formed
first and the first fin mask FM1 may be formed after the second fin
mask FM2 is removed. However, FIG. 2 illustrates both the first and
second fin masks FM1 and FM2 together to show the relative position
of the first and second fin masks FM1 and FM2.
[0026] The first fin mask FM1 is a line type mask that is formed
along a first direction, and the second fin mask FM2 is an island
type mask that is formed along a second direction that is
orthogonal to the first direction. Using the first fin mask FM1 and
the second fin mask FM2 in combination allows selectively etching
portions of the active region 101 and the isolation structure 102
predetermined for forming the saddle type fins 103. That is,
portions where dummy saddle type fins usually occur (i.e., the ends
104 along the major axis of two neighboring active regions 101
along the X axis) are not etched during an etching process for
forming the saddle type fins 103. This result may be obtained
because the island type second fin mask FM2 is applied.
[0027] For instance, the second fin mask FM2 may be an island type
mask of a rectangular shape formed to cover the ends 104 along the
major axis of the neighboring active regions 101 and cover the
isolation structure 102 between the two active regions 101. The
second fin mask FM2 is formed at least partly to intersect the
location where the first fin mask FM1 was formed. The first fin
mask FM1 and the second fin mask FM2 may be applied in a certain
order. A hard mask pattern transcribing the shape of the first fin
mask FM1 and the second fin mask FM2 in combination is used as an
etch barrier when forming the saddle type fins 103.
[0028] FIGS. 3A to 3E illustrate cross-sectional views of a method
for fabricating a saddle type fin according to the first embodiment
of the present invention.
[0029] Referring to FIG. 3A, an isolation structure 24 is formed in
a substrate 21 using a shallow trench isolation (STI) process. The
isolation structure 24 defines an active region 21A. A pad oxide
layer 22 and a pad nitride layer 23 are formed over the active
region 21A. In more detail, the STI process includes forming an
oxide-based layer and a nitride-based layer over the substrate 21
in sequential order when forming the isolation structure 24. An
etching process is performed to form trenches in the substrate 21
using an STI mask. The STI mask is removed. An insulation layer
(e.g., a high density plasma (HDP) oxide layer) is filled in the
trenches, and a chemical mechanical polishing (CMP) process is
performed. Consequently, the pad oxide layer 22 and the pad nitride
layer 23 are formed over the active region 21A after the CMP
process is performed. The active region 21A includes an island type
pattern having a major axis and a minor axis. In a plan view, the
active region 21A has substantially the same shape and layout as
the active regions 101 shown in FIG. 2.
[0030] An amorphous carbon layer 25, a dielectric anti-reflective
coating (DARC) layer 26, a polysilicon hard mask 27, and a first
patterned bottom anti-reflective coating (BARC) layer 28A are
formed over the resulting substrate structure. In more detail, the
amorphous carbon layer 25, the DARC layer 26, a polysilicon hard
mask layer, and a first BARC layer are formed over the substrate
structure. The selectivity between the DARC layer 26 and the
amorphous carbon layer 25 is approximately 10:1 or higher. Thus,
the DARC layer 26 functions as a hard mask when etching the
amorphous carbon layer 25. The polysilicon hard mask layer
functions as a hard mask when etching the DARC layer 26. Both the
DARC layer 26 and the polysilicon hard mask layer may have a
thickness of approximately 1,000 .ANG. or less. The amorphous
carbon layer 25 may be used as a hard mask for forming a subsequent
saddle type fin. The amorphous carbon layer 25 may have a thickness
of approximately 500 .ANG. or greater.
[0031] A first fin mask (FM1) 29 is formed over the first BARC
layer. The FM1 29 includes a photoresist layer patterned by a
photo-exposure and developing process. The FM1 29 includes line
type first openings 29A exposing saddle type fin regions. That is,
the FM1 29 is formed in a line mask shape, wherein the first
openings 29A are formed to intersect with the major axis of the
active region 21A. The active region 21A and the FM1 29 are
disposed in substantially the same manner as the active regions 101
and the first fin mask FM1 shown in FIG. 2.
[0032] An etching process is performed to etch the first BARC layer
and the polysilicon hard mask layer using the FM1 29 as an etch
mask. Consequently, the first patterned BARC layer 28A and the
polysilicon hard mask 27 are formed. Thus, the polysilicon hard
mask 27 is formed in a line type pattern, transcribing the shape of
the FM1 29.
[0033] Referring to FIG. 3B, the FM1 29 is removed. The first
patterned BARC layer 28A is also removed at this time. A second
BARC layer 28B is formed over the resultant substrate structure. A
second fin mask (FM2) 30 is formed over the second BARC layer 28B.
The FM2 30 includes a photoresist layer patterned by a
photo-exposure and developing process. In a plan view, the FM2 30
covers the ends of two neighboring active regions 21A along the
major axis. Thus, the FM2 30 exposes the saddle type fin regions
through a second opening 30A, and yet covers the ends of the active
regions 21A along the major axis where the dummy saddle type fins
may form and the isolation structure 24 formed between the ends.
The FM2 30 is formed in an island shape. Thus, the FM2 30 and the
FM1 29 are shaped differently.
[0034] Referring to FIG. 3C, an etching process is performed using
the FM2 30 as an etch mask. That is, the second BARC layer 28B and
the DARC layer 26 are etched to form a patterned second BARC layer
28C and a patterned DARC layer 26A. At this time, the polysilicon
hard mask 27 may not be etched. Thus, the DARC layer 26 below the
polysilicon hard mask 27 is etched in a manner such that the
patterned DARC layer 26A is self-aligned by the polysilicon hard
mask 27. Referring to FIG. 3D, the FM2 30 is removed. The patterned
second BARC layer 28C is also removed at this time.
[0035] Referring to FIG. 3E, the polysilicon hard mask 27 is
removed. The amorphous carbon layer 25 is etched to form an
amorphous carbon pattern 25A using the patterned DARC layer 26A as
a mask. A plan view of the amorphous carbon pattern 25A
transcribing the shape of the patterned DARC layer 26A is shown in
FIG. 4. The pad nitride layer 23 and the pad oxide layer 22 are
etched to form a patterned pad nitride layer 23A and a pad oxide
layer 22A. The isolation structure 24 and the active region 21A are
then selectively recessed to form saddle type fins 31. Reference
numeral 24A represents recessed portions of the isolation structure
24. The patterned DARC layer 26A is etched away when forming the
saddle type fins 31. The amorphous carbon pattern 25A functions as
an etch barrier.
[0036] The amorphous carbon pattern 25A prevents the etching of the
ends of two neighboring active regions 21A along the major axis
when forming the saddle type fins 31. Consequently, only the saddle
type fin regions (refer to line B-B') of the active region 21A and
the isolation structure 24 are etched. The active regions 21A and
the isolation structure 24 at the ends of the active regions 21A
along the major axis where the dummy saddle type fins often occur
may not be etched. The resultant saddle type fins 31 are described
in a plan view in FIG. 4.
[0037] FIG. 4 illustrates the resultant saddle type fins according
to the first embodiment of the present invention. The amorphous
carbon pattern 25A formed by the combination of the FM1 29 and the
FM2 30 exposes the saddle type fin regions (refer to line B-B') of
the active regions 21A with rectangular type openings 100A. The
amorphous carbon pattern 25A covers regions where dummy saddle type
fins often occur as denoted with reference numeral 100B.
[0038] Accordingly, forming the saddle type fins 31 by etching
using the amorphous carbon pattern 25A reduces the etching of the
ends of the active regions 21A along the major axis. Thus, the
dummy saddle type fins are not formed. The saddle type fin regions
to be etched are defined in a rectangular shape by the rectangular
type openings 100A and are locally etched. Thus, the saddle type
fins 31 according to the first embodiment may be referred to as
local damascene saddle type fins (LD-SF).
[0039] In the aforementioned first embodiment, the line type FM1 29
is used before using the island type FM2 30. However, an amorphous
carbon pattern having substantially the same shape as the one shown
in FIG. 4 may be obtained even when the island type FM2 30 is used
before using the line type FM1 29.
[0040] FIG. 5A illustrates a plan view of a fin mask combination
used in fabricating a saddle type fin according to a second
embodiment of the present invention. A second fin mask (FM21) of
the fin mask combination according to the second embodiment has a
shape different from the second fin mask (FM2) according to the
first embodiment.
[0041] A plurality of active regions 111 are formed in a substrate.
The substrate has a flat surface with an X axis and a Y axis. The
active regions 111 are formed in a particular size with a major
axis and a minor axis. The active regions 111 are disposed in a
manner that the ends 114 along the major axis of two neighboring
active regions 111 along the X axis are adjacent to each other, and
an isolation structure 112 is formed between the adjacent active
regions 111. Hereinafter, only one set of elements are described
for convenience.
[0042] The active region 111 is defined by the isolation structure
112. Forming a fin mask according to the second embodiment includes
using a first fin mask FM11 and a second fin mask FM21 in
combination to form saddle type fins 113. The active region 111 and
the isolation structure 112 are selectively etched to form the
saddle type fins 113, that is, the active region 111 protruding in
a saddle type structure. In the present embodiment, the first fin
mask FM11 and the second fin mask FM21 may be sequentially used
according to a given order, and the given order may be changeable.
For instance, the first fin mask FM11 may be formed first and the
second fin mask FM21 may be formed after the first fin mask FM11 is
removed. On the other hand, the second fin mask FM21 may be formed
first and the first fin mask FM11 may be formed after the second
fin mask FM21 is removed. However, FIG. 5A illustrates both the
first and second fin masks FM11 and FM21 together to show the
relative position of the first and second fin masks FM11 and
FM21.
[0043] The first fin mask FM11 is a line type mask that is formed
along a first direction, and the second fin mask FM21 is an island
type mask that is formed along a second direction that is
orthogonal to the first direction. The saddle type fin regions of
the active region 111 and the isolation structure 112, where the
saddle type fins 113 are to be formed, may be locally etched by
combining the two fin masks. That is, portions where dummy saddle
type fins usually occur (i.e., the ends 114 along the major axis of
two neighboring active regions 111 along the X axis) are not etched
during an etching process for forming the saddle type fins 113.
This result may be obtained because the island type second fin mask
FM21 is applied.
[0044] For instance, the second fin mask FM21 may be a
dumbbell-shaped island type mask formed to cover the ends 114 along
the major axis of the neighboring active regions 111 and cover the
isolation structure 112 between the two active regions 111. The
dumbbell-shaped island type mask includes a rectangular shape over
the isolation structure 112 between the neighboring active regions
111. The dumbbell-shaped island type mask also includes a ball or
an ellipse shape over the ends 114 of each active region 111 such
that the dumbbell-shaped island type mask covers the ends 114 with
an increased surface area. The second fin mask FM21 is formed to
intersect at least partly the location where the first fin mask
FM11 was formed.
[0045] The second fin mask FM21 is formed as the dumbbell-shaped
island type mask according to the second embodiment unlike the
second fin mask FM2 that is formed as a rectangular island type
mask according to the first embodiment. Using the second fin mask
FM21 of the dumbbell-shaped island type may increase the margin for
covering the ends 114 of the active region 111. That is, the margin
for reducing the chances of dummy saddle type fin generation at the
ends 114 of the active region 111 may increase.
[0046] The first fin mask FM11 and the second fin mask FM21 may be
applied in a certain order (i.e., FM11.fwdarw.FM21 or
FM21.fwdarw.FM11). A hard mask pattern transcribing the shape of
the first fin mask FM11 and the second fin mask FM21 in combination
is used as an etch barrier when forming the saddle type fins 113.
The etch barrier may include an amorphous carbon pattern. The
amorphous carbon pattern may be formed by employing the first fin
mask FM11, the second fin mask FM21, a DARC layer, and a
polysilicon hard mask. The amorphous carbon pattern may be formed
using the method shown in FIGS. 3A to 3E. FIG. 5B illustrates a
scanning electron microscopic (SEM) view of a second fin mask
according to the second embodiment of the present invention.
[0047] FIG. 6A illustrates a plan view of a fin mask combination
used in fabricating a saddle type fin according to a third
embodiment of the present invention. The fin mask combination
according to the third embodiment includes a first fin mask FM31 of
a line type and a second fin mask FM32 of a jigsaw puzzle type for
locally etching active regions 200 and an isolation structure to
form saddle type fins 201.
[0048] The first fin mask FM31 is a line type mask exposing only
the saddle type fin regions of the active regions 200, where the
saddle type fins 201 are to be formed. The first fin mask FM31 is
substantially the same as the first fin masks according to the
first and second embodiments. The second fin mask FM32 is a jigsaw
puzzle type mask. That is, the second fin mask FM32 having the
jigsaw puzzle shape covers ends of the active regions 200 along a
major axis as well as between the ends. Meanwhile, the second fin
mask FM32 exposes the rest of the substrate structure through
jigsaw puzzle openings 202. Regions exposed by the jigsaw puzzle
openings 202 are locally etched to form the saddle type fins
201.
[0049] Using the second fin mask FM32 of jigsaw puzzle type
according to the third embodiment may allow the selectivity of a
photoresist layer to be maintained, which may otherwise be
insufficient. Thus, the ends of the active regions 200 along the
major axis where dummy saddle type fins often occur may be
sufficiently covered.
[0050] The first fin mask FM31 and the second fin mask FM32 are
applied in a certain order (i.e., FM31.fwdarw.M32 or
FM32.fwdarw.FM31). A hard mask pattern transcribing the shape of
the first fin mask FM31 and the second fin mask FM32 in combination
is used as an etch barrier pattern when forming the saddle type
fins 201. The etch barrier pattern may include an amorphous carbon
pattern. The amorphous carbon pattern may be formed by employing
the first fin mask FM31, the second fin mask FM32, a DARC layer,
and a polysilicon hard mask. The amorphous carbon pattern may be
formed using the method shown in FIGS. 3A to 3E. FIG. 6B
illustrates a SEM view of the second fin mask shown in FIG. 6A.
[0051] FIG. 7A illustrates a plan view of a fin mask used in
fabricating a saddle type fin according to a fourth embodiment of
the present invention. FIG. 7B illustrates a SEM view of the fin
mask shown in FIG. 7A.
[0052] Referring to FIG. 7A, unlike the first to third embodiments,
a fin mask R-FM having island-shaped openings 302 is used
independently without using a line type first fin mask. That is,
the fin mask R-FM having the openings 302 locally exposes saddle
type fin regions of active regions 300, where saddle type fins 301
are to be formed. The rest of the substrate structure is covered by
the fin mask R-FM. The openings 302 may have a rectangular shape as
illustrated or an elliptical shape.
[0053] Using the fin mask R-FM having the island-shaped openings
302 independently may simplify the process when compared to using
two fin masks. Also, using the fin mask R-FM according to the
fourth embodiment generally does not require using a polysilicon
hard mask. The saddle type fins 301 may be formed using only
amorphous carbon. The saddle type fins 301 may include polysilicon
instead of amorphous carbon. Therefore, a hard mask stack may be
simply configured using the fin mask R-FM according to the fourth
embodiment. For instance, an etch barrier pattern transcribing the
shape of the fin mask R-FM is used as an etch barrier when forming
the saddle type fins 301 using the fin mask R-FM according to the
fourth embodiment. The etch barrier pattern may include an
amorphous carbon pattern or a polysilicon pattern. The etch barrier
pattern may be formed by employing the fin mask R-FM and a DARC
layer. The etch barrier pattern may be formed using the method
shown in FIGS. 3A to 3E. According to the fourth embodiment, the
DARC layer may be directly etched using the fin mask R-FM without
using the polysilicon hard mask, and the amorphous carbon may be
etched using the DARC layer. Also, polysilicon may be used as an
etch barrier when forming the saddle type fins by forming
polysilicon under the DARC layer instead of amorphous carbon.
[0054] Saddle type fins may be formed in a local damascene form
when the saddle type fins are formed using the fin mask combination
or the independent fin mask R-FM according to the first to the
fourth embodiments. Since the saddle type fin regions are limited
and locally etched, the saddle type fins become local damascene
saddle type fins (LD-SF). FIG. 8 illustrates a SEM view of saddle
type fins according to embodiments of the present invention. The
saddle type fins are formed as represented with `LD-SF.`
[0055] While the present invention has been described with respect
to specific embodiments, it will be apparent to those skilled in
the art that various changes and modifications may be made without
departing from the spirit and scope of the invention as defined in
the following claims.
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