U.S. patent application number 13/887766 was filed with the patent office on 2014-11-06 for method to make dual material finfet on same substrate.
This patent application is currently assigned to International Business Machines Corporation. The applicant listed for this patent is INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Effendi Leobandung.
Application Number | 20140327044 13/887766 |
Document ID | / |
Family ID | 51661070 |
Filed Date | 2014-11-06 |
United States Patent
Application |
20140327044 |
Kind Code |
A1 |
Leobandung; Effendi |
November 6, 2014 |
METHOD TO MAKE DUAL MATERIAL FINFET ON SAME SUBSTRATE
Abstract
A method of fabricating a semiconductor device including proving
a substrate having a germanium containing layer that is present on
a dielectric layer, and etching the germanium containing layer of
the substrate to provide a first region including a germanium
containing fin structure and a second region including a mandrel
structure. A first gate structure may be formed on the germanium
containing fin structures. A III-V fin structure may then be formed
on the sidewalls of the mandrel structure. The mandrel structure
may be removed. A second gate structure may be formed on the III-V
fin structure.
Inventors: |
Leobandung; Effendi;
(Wappingers Falls, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
Armonk |
NY |
US |
|
|
Assignee: |
International Business Machines
Corporation
Armonk
NY
|
Family ID: |
51661070 |
Appl. No.: |
13/887766 |
Filed: |
May 6, 2013 |
Current U.S.
Class: |
257/192 ;
438/157 |
Current CPC
Class: |
H01L 27/0886 20130101;
H01L 21/823807 20130101; H01L 27/1211 20130101; H01L 21/823821
20130101; H01L 29/201 20130101; H01L 27/0924 20130101; H01L
21/823431 20130101; H01L 27/10826 20130101; H01L 27/10879 20130101;
H01L 29/16 20130101; H01L 29/66795 20130101; H01L 21/845 20130101;
H01L 29/785 20130101; H01L 29/20 20130101; H01L 29/41791
20130101 |
Class at
Publication: |
257/192 ;
438/157 |
International
Class: |
H01L 29/66 20060101
H01L029/66; H01L 29/78 20060101 H01L029/78 |
Claims
1. A method of fabricating a semiconductor device comprising:
proving a substrate having a germanium containing layer that is
present on a dielectric layer; etching the germanium containing
layer of the substrate to provide a first region including a
germanium containing fin structure and a second region including a
mandrel structure; forming a first gate structure on the germanium
containing fin structure; forming a III-V fin structure on a
sidewall of the mandrel structure; removing the mandrel structure;
and forming a second gate structure on the III-V fin structure.
2. The method of claim 1, wherein the germanium containing fin
structure has a width ranging from 2 nm to 12 nm, and the mandrel
structure has a width ranging from 15 nm to 45 nm.
3. The method of claim 1, wherein the substrate includes a
semiconductor on insulator substrate, wherein the SOI substrate
includes a semiconductor on insulator (SOI) layer on the dielectric
layer, wherein the SOI layer provides the germanium containing
layer.
4. The method of claim 1, wherein the germanium containing layer is
silicon germanium or germanium.
5. The method of claim 1, wherein the etching of the substrate
comprises: forming a mask protecting portions of the germanium
containing layer that provide the germanium containing fin
structure and the mandrel structure; etching exposed portion of the
germanium containing layer with an anisotropic etch; and removing
the mask.
6. The method of claim 1, wherein forming the first gate structure
on the germanium containing fin structure comprises: depositing a
first gate dielectric layer on the first region and second region
of the substrate; depositing a first gate conductor layer on the
first region and second region of the substrate; forming first
block mask over the first region, wherein the first block mask is
not present over the second region; and removing a portion of the
first gate dielectric layer and the first gate conductor layer in
the second region.
7. The method of claim 1, wherein forming the III-V fin structure
on the sidewall of the mandrel structure comprises an epitaxial
growth process.
8. The method of claim 1, wherein the III-V fin structure has a
width ranging from 2 nm to 12 nm.
9. The method of claim 1, wherein removing the mandrel structure
comprises an etch process that is selective to the III-V fin
structures.
10. The method of claim 1, wherein forming the second gate
structure on the III-V fin structure comprises: depositing a second
gate dielectric layer on the first region and second region of the
substrate; depositing a second gate conductor layer on the first
region and second region of the substrate; forming a second block
mask over the second region, wherein the block mask is not present
over the first region; and removing the portion of the second gate
dielectric layer and the second gate conductor layer in the first
region.
11. The method of claim 1 further comprising forming a source
region and a drain region on the III-V fin structure and the
germanium containing fin structure.
12.-19. (canceled)
Description
BACKGROUND
[0001] The present disclosure relates generally to semiconductor
devices. More particularly, the present disclosure relates to
semiconductor devices having a fin structure.
[0002] In order to be able to make integrated circuits (ICs), such
as memory, logic, and other devices, of higher integration density
than currently feasible, one has to find ways to further downscale
the dimensions of field effect transistors (FETs), such as
metal-oxide-semiconductor field effect transistors (MOSFETs) and
complementary metal oxide semiconductors (CMOS). Scaling achieves
compactness and improves operating performance in devices by
shrinking the overall dimensions and operating voltages of the
device while maintaining the device's electrical properties. In
view of the possibility of scaling reaching its limits, other
semiconductor geometries, such as fin field effect transistors
(finFETs) have been considered.
SUMMARY
[0003] A method of fabricating a semiconductor device is provided
that includes providing a substrate having a germanium containing
layer that is present on a dielectric layer, and etching the
substrate to provide a first region including a germanium
containing fin structure and a second region including a mandrel
structure. A first gate structure may be formed on the germanium
containing fin structure. A III-V fin structures may then be formed
on the sidewall of the mandrel structure. The mandrel structure may
be removed. A second gate structure may be formed on the III-V fin
structure.
[0004] In another aspect, a semiconductor device is provided. In
one embodiment, the semiconductor device includes a substrate
having a first device region and a second device region. The first
device region may include a p-type fin field effect transistor
including a first fin structure comprised of a germanium containing
material. The second device region may include an n-type fin field
effect transistor including second fin structure comprised of a
III-V semiconductor material.
DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0005] The following detailed description, given by way of example
and not intended to limit the present disclosure solely thereto,
will best be appreciated in conjunction with the accompanying
drawings, wherein like reference numerals denote like elements and
parts, in which:
[0006] FIG. 1 is a side cross-sectional view of a semiconductor
substrate having a germanium containing layer that is present on a
dielectric layer, as used in accordance with one embodiment of the
present disclosure.
[0007] FIG. 2 is a side cross-sectional view depicting one
embodiment of etching the semiconductor substrate to provide a
first region including a germanium containing fin structure and a
second region including a mandrel structure, in accordance with one
embodiment of the present disclosure.
[0008] FIG. 3 is a side cross-sectional view depicting one
embodiment of forming a first gate structure on the germanium
containing fin structure, in accordance with the present
disclosure.
[0009] FIG. 4 is a side cross-sectional view depicting forming a
III-V fin structure on a sidewall of the mandrel structure, in
accordance with one embodiment of the present disclosure.
[0010] FIG. 5 is a side cross-sectional view depicting one
embodiment of removing the mandrel structure.
[0011] FIG. 6A is a side cross-sectional view depicting forming a
second gate structure on the III-V fin structure, in accordance
with the present disclosure.
[0012] FIG. 6B is a top down planar view of the structure depicted
in FIG. 6A.
DETAILED DESCRIPTION
[0013] Detailed embodiments of the methods and structures of the
present disclosure are described herein; however, it is to be
understood that the disclosed embodiments are merely illustrative
of the disclosed methods and structures that may be embodied in
various forms. In addition, each of the examples given in
connection with the various embodiments of the disclosure are
intended to be illustrative, and not restrictive. Further, the
figures are not necessarily to scale, some features may be
exaggerated to show details of particular components. Therefore,
specific structural and functional details disclosed herein are not
to be interpreted as limiting, but merely as a representative basis
for teaching one skilled in the art to variously employ the methods
and structures of the present disclosure. For the purposes of the
description hereinafter, the terms "upper", "lower", "top",
"bottom", and derivatives thereof shall relate to the disclosed
structures, as they are oriented in the drawing figures.
[0014] The methods and structures disclosed herein provide fin
structures, such as fin field effect transistors (finFETs). As used
herein, the term "fin structure" refers to a semiconductor
material, which is employed as the body of a semiconductor device,
in which the gate structure is positioned around the fin structure
such that charge flows down the channel on the two sidewalls of the
fin structure and optionally along the top surface of the fin
structure. In some embodiments, the methods and structures
disclosed herein provide a first conductivity finFET having a fin
structure composed of a germanium containing material and a second
conductivity finFET having a fin structure composed of a III-V
semiconductor material on the same substrate. By "same substrate"
it is meant that the first conductivity finFET, e.g., p-type
finFET, and the second conductivity finFET, e.g., n-type finFET,
are present simultaneously on the same substrate in different
regions of the same substrate. Typically, the first conductivity
finFET and the second conductivity finFET are present on a same
surface, e.g., upper surface, of the semiconductor substrate.
[0015] FIGS. 1-6 depict one embodiment of a method of fabricating a
first conductivity finFET 100a, e.g., p-type finFET, having a first
fin structure 10 composed of a germanium containing material and a
second conductivity finFET, e.g., n-type finFET 100b, having a
second fin structure 20 composed of a III-V semiconductor material
on the same substrate 5.
[0016] FIG. 1 depicts one embodiment of a semiconductor substrate 1
having a germanium containing layer 4 that is present on a
dielectric layer 3, e.g., buried dielectric layer 3. In some
embodiments, the semiconductor substrate 1 includes a germanium
containing layer 4 that is present on a buried dielectric layer 3,
wherein the buried dielectric layer 3 is present on a base
semiconductor layer 2. The semiconductor substrate 1 may be a
silicon germanium on insulator (SGOI) substrate or a germanium on
insulator (GOI) substrate.
[0017] The germanium containing layer 4 may be composed of silicon
germanium (SiGe). In some embodiments, the germanium containing
layer 4 may be composed of silicon germanium (SiGe) or germanium
(Ge). For example, the germanium containing layer 4 may be composed
of up to 99 wt. % germanium. In one embodiment, the germanium
containing layer 4 comprises from 1 wt. % germanium to 99 wt. %
germanium. In another embodiment, the germanium containing layer 4
is composed of 10 wt. % to 50 wt. % germanium. In yet another
embodiment, the germanium containing layer 4 is composed of 100 wt.
% germanium.
[0018] The germanium containing layer 4 may be a single layer
having a continuous distribution of germanium, or it may be a
graded layer having a varying content of germanium included within
different regions of the layer. The thickness of the germanium
containing layer 4 may range from 5 nm to 5000 nm. In another
embodiment, the germanium containing layer 4 may have a thickness
that ranges from 20 nm to 200 nm.
[0019] The germanium containing layer 4 is typically present on,
e.g., in direct contact with, a dielectric layer 3 (also referred
to as a buried dielectric layer). The term "direct contact" means
that a first element, such as a first structure, and a second
element, such as a second structure, are connected without any
intermediary conducting, insulating or semiconductor layers at the
interface of the two elements. The dielectric layer 3 may be
composed of an oxide, nitride or oxynitride material. For example,
when the dielectric layer 3 is composed of an oxide, the dielectric
layer 3 may be silicon oxide. In another example, when the
dielectric layer is composed of a nitride, the dielectric layer 3
may be silicon nitride. The base semiconductor layer 2 may be a
semiconducting material including, but not limited to Si, strained
Si, SiC, SiGe, SiGeC, Si alloys, Ge, Ge alloys, GaAs, InAs, InP as
well as other III/V and II/VI compound semiconductors.
[0020] In one embodiment, the semiconductor substrate 1 that is
depicted in FIG. 1 may be formed by depositing the buried
dielectric layer 3 on the base semiconductor layer 2 and then
depositing the germanium containing layer 4 on the buried
dielectric layer 3. The semiconductor substrate 1 depicted in FIG.
1 may also be formed by wafer bonding methods. In yet another
embodiment, a germanium layer may be formed on the silicon on
insulator (SOI) layer of a silicon on insulator (SOI) substrate.
Thereafter, the germanium layer and the SOI layer of the SOI
substrate may be annealed to thermally mix the germanium from the
germanium containing layer with the silicon of the SOI layer to
form the germanium containing layer 4 of the semiconductor
substrate 1 that is depicted in FIG. 1.
[0021] FIG. 2 is depicts one embodiment of etching the
semiconductor substrate 1 to provide a first region including
germanium containing fin structures 10 and a second region
including a mandrel structure 20. More specifically, the germanium
containing fin structures 10 and the mandrel structure 20 are
typically formed from the germanium containing layer 4 of the
semiconductor substrate 1. The term "mandrel" denotes a sacrificial
structure that provides the deposition surface of a later formed
fin structure for the second region of the substrate 5. The mandrel
structure 20 typically has a width W2 that is larger than the width
W1 of the germanium containing fin structures 10. For example, in
one embodiment, the width W2 of the mandrel structure 20 may range
from 15 nm to 45 nm, and the width W1 of each of the germanium
containing fin structures 10 may range from 2 nm to 12 nm. In
another embodiment, the width W2 of the mandrel structure 20 may
range from 20 nm to 40 nm, and the width W1 of the germanium
containing fin structures 10 may range from 5 nm to 10 nm.
[0022] In some embodiments, prior to etching the germanium
containing layer 4, a dielectric cap layer 30 may be formed atop
the germanium containing layer 4. The dielectric cap layer 30 may
be composed of an oxide, nitride or oxynitride layer. For example,
the dielectric cap layer 30 may be composed of silicon oxide or
silicon nitride. The dielectric cap layer 30 may have a thickness
ranging from 5 nm to 200 nm. In another embodiment, the dielectric
cap layer 30 may have a thickness ranging from 10 nm to 100 nm. The
dielectric cap layer 30 may be formed by a deposition or a forming
method that is selected from the group consisting of chemical vapor
deposition (CVD), chemical solution deposition, thermal growth,
spin on deposition or a combination thereof.
[0023] Following the formation of the dielectric cap layer 30, the
dielectric cap layer 30 and the germanium containing layer 4 of the
semiconductor substrate 1 may be etched. In one embodiment, etching
the dielectric cap layer 30 and the germanium containing layer 4
may include forming a patterned photoresist layer, i.e., photomask,
on the dielectric cap layer 30, and over the germanium containing
layer 4, and etching the dielectric cap layer 30 and the germanium
containing layer 4 selectively to the photomask and the buried
dielectric layer 3. In one embodiment, a pattern is produced by
applying a photoresist to the surface to be etched, exposing the
photoresist to a pattern of radiation, and then developing the
pattern into the photoresist utilizing a resist developer. Once the
patterning of the photoresist is completed, the sections of the
dielectric cap layer 30 and the germanium containing layer 4
covered by the photoresist are protected to provide the germanium
containing fin structures 10 and the mandrel structure 20, while
the exposed regions are removed using a selective etching process.
As used herein, the term "selective" in reference to a material
removal process denotes that the rate of material removal for a
first material is greater than the rate of removal for at least
another material of the structure to which the material removal
process is being applied. For example, in one embodiment, a
selective etch may include an etch chemistry that removes a first
material selectively to a second material by a ratio of 10:1 or
greater. In one embodiment, the etch chemistry is selected to
remove at least one of the germanium containing layer 4 and the
dielectric cap layer 30 selectively to the buried dielectric layer
3. The remaining portion of the semiconductor substrate 1 may now
be referred to as a substrate 5, which has a dielectric upper
surface provided by the buried dielectric layer 3.
[0024] In one embodiment, the etch process for forming the
germanium containing fin structures 10 and the mandrel structure 20
is an anisotropic etch. An anisotropic etch process is a material
removal process in which the etch rate in the direction normal to
the surface to be etched is greater than in the direction parallel
to the surface to be etched. The anisotropic etch may include
reactive-ion etching (RIE). Other examples of anisotropic etching
that can be used at this point of the present disclosure include
ion beam etching, plasma etching or laser ablation.
[0025] Each of the germanium containing fin structures 10 may have
a height ranging from 5 nm to 200 nm. In one embodiment, each of
the germanium containing fin structures 10 may have height ranging
from 10 nm to 100 nm. In another embodiment, each of the germanium
containing fin structures 10 may have a height ranging from 15 nm
to 50 nm. Each of the germanium containing fin structures 10 may
have a width W.sub.1 ranging from 5 nm to 50 nm. In another
embodiment, each of the germanium containing fin structures 10 may
have width W.sub.1 ranging from 8 nm to 20 nm. Adjacent germanium
containing fin structures 10 may be separated by a pitch P1 ranging
from 20 nm to 100 nm. In one embodiment, adjacent germanium
containing fin structures 10 may be separated by a pitch P1 ranging
from 30 nm to 50 nm.
[0026] FIG. 3 depicts one embodiment of forming a first gate
structure 15 on the germanium containing fin structures 10. In one
embodiment, the first gate structure 15 includes a first gate
dielectric layer 13 and a first gate conductor layer 14. The first
gate dielectric layer 13 is typically formed on the channel portion
of the germanium containing fin structure 10.
[0027] The at least one first gate dielectric layer 13 of the first
gate structure 15 may be composed of any dielectric material
including oxides, nitrides and oxynitrides. In one embodiment, the
at least one first gate dielectric layer 13 may be provided by a
high-k dielectric material. The term "high-k" as used to describe
the material of the at least one first gate dielectric layer 13
denotes a dielectric material having a dielectric constant greater
than silicon oxide (SiO.sub.2) at room temperature (20.degree. C.
to 25.degree. C.) and atmospheric pressure (1 atm). For example, a
high-k dielectric material may have a dielectric constant greater
than 4.0. In another example, the high-k gate dielectric material
has a dielectric constant greater than 7.0. In one embodiment, the
at least one first gate dielectric layer 13 is composed of a high-k
oxide, such as, for example, HfO.sub.2, ZrO.sub.2, Al.sub.2O.sub.3,
TiO.sub.2, La.sub.2O.sub.3, SrTiO.sub.3, LaAlO.sub.3,
Y.sub.2O.sub.3 and mixtures thereof. Other examples of high-k
dielectric materials for the at least one first gate dielectric
layer 13 include hafnium silicate, hafnium silicon oxynitride or
combinations thereof. In one embodiment, the at least one first
gate dielectric 13 may be deposited by chemical vapor deposition
(CVD). Variations of CVD processes suitable for depositing the at
least one first gate dielectric layer 13 include, but are not
limited to, APCVD, LPCVD, PECVD, MOCVD, ALD, and combinations
thereof. In one embodiment, the thickness of the at least one first
gate dielectric layer 13 is greater than 0.8 nm. More typically,
the at least one first gate dielectric layer 13 has a thickness
ranging from about 1.0 nm to about 6.0 nm.
[0028] The at least one first gate conductor layer 14 is formed on
the at least one first gate dielectric layer 13. The at least one
first gate conductor layer 14 may be formed by a deposition
process, such as CVD, plasma-assisted CVD, plating, and/or
sputtering, followed by planarization. In one embodiment, the at
least one first gate conductor layer 14 is composed of metal or a
doped semiconductor. Examples of metals that may be employed for
the at least one first gate conductor layer 14 may include, but is
not limited to, W, Ni, Ti, Mo, Ta, Cu, Pt, Ag, Au, Ru, Ir, Rh, and
Re, Al, TiN, WN, TaN, TiAlN, TaAlN, and alloys thereof. One example
of a doped semiconductor that is suitable for the at least one
first gate conductor layer 14 is doped polysilicon.
[0029] In some embodiments, in which the first conductivity finFET
that is formed in the first device region of the substrate 5 is a
p-type finFET, the at least one first gate conductor layer 14 may
include a metal that is a p-type work function metal layer. As used
herein, a "p-type work function metal layer" is a metal layer that
effectuates a p-type threshold voltage shift. In one embodiment,
the work function of the p-type work function metal layer ranges
from 4.9 eV to 5.2 eV. As used herein, "threshold voltage" is the
lowest attainable gate voltage that will turn on a semiconductor
device, e.g., transistor, by making the channel of the device
conductive. The term "p-type threshold voltage shift" as used
herein means a shift in the Fermi energy of a p-type semiconductor
device towards a valence band of silicon in the silicon containing
substrate of the p-type semiconductor device. A "valence band" is
the highest range of electron energies where electrons are normally
present at absolute zero.
[0030] In one embodiment, the p-type work function metal layer may
be composed of titanium and their nitrided/carbide. In one
embodiment, the p-type work function metal layer is composed of
titanium nitride (TiN). The p-type work function metal layer may
also be composed of TiAlN, Ru, Pt, Mo, Co and alloys and
combinations thereof. In one embodiment, the p-type work function
metal layer comprising titanium nitride (TiN) may be deposited by a
physical vapor deposition (PVD) method, such as sputtering.
Examples of sputtering apparatus that may be suitable for
depositing the p-type work function metal layer include DC diode
type systems, radio frequency (RF) sputtering, magnetron
sputtering, and ionized metal plasma (IMP) sputtering. In addition
to physical vapor deposition (PVD) techniques, the p-type work
function metal layer may also be formed using chemical vapor
deposition (CVD) and atomic layer deposition (ALD).
[0031] The at least one first gate structure 15 may be formed using
deposition, photolithography and etch processes. The at least one
first gate structure 15 is formed on a channel portion of the at
least one germanium containing fin structure 10. For example, the
material layers for the at least one first gate dielectric layer 13
and the at least one gate conductor layer 14 may be deposited onto
the silicon germanium fin structures 10 to provide a gate stack.
Thereafter, the gate stack may be patterned and etched to provide
the at least one first gate structure 15.
[0032] Specifically, and in one example, a pattern is produced by
applying a photoresist to the surface to be etched, exposing the
photoresist to a pattern of radiation, and then developing the
pattern into the photoresist utilizing a resist developer. Once the
patterning of the photoresist is completed, the sections of the
stack of the at least one gate dielectric layer 13 and the at least
one gate conductor layer 14 covered by the photoresist are
protected to provide the at least one first gate structures 15,
while the exposed regions are removed using a selective etching
process that removes the unprotected regions. For example, the
portion of the at least one first gate dielectric layer 13 and the
at least one first gate conductor layer 14 that is present over the
second region of the substrate 5 including the mandrel structure 20
may be removed. Following formation of the at least one first gate
structure 15, the photoresist may be removed.
[0033] FIG. 4 depicts one embodiment of forming III-V fin
structures 40 on the sidewalls of the mandrel structure 20. The
term "III-V semiconductor" denotes a semiconductor material that
includes at least one element from Group III of the Periodic Table
of Elements and at least one element from Group V of the Periodic
Table of Elements. Typically, the III-V compound semiconductors are
binary, ternary or quaternary alloys including III/V elements.
Examples of III-V compound semiconductors that can be used in the
present invention include, but are not limited to alloys of gallium
arsenic (GaAs), aluminum arsenic (AlAs), indium gallium arsenic
(InGaAs), indium aluminum arsenic (InAlAs), indium aluminum arsenic
antimony (InAlAsSb), indium aluminum arsenic phosphorus (InAlAsP),
indium gallium arsenic phosphorus (InGaAsP) and combinations
thereof.
[0034] In some embodiments, the III-V fin structures 40 may be
formed on the mandrel structure 20 using an epitaxial deposition
process. The terms "epitaxial growth and/or deposition" and
"epitaxially formed and/or grown" mean the growth of a
semiconductor material on a deposition surface of a semiconductor
material, in which the semiconductor material being grown has the
same crystalline characteristics as the semiconductor material of
the deposition surface. In an epitaxial deposition process, the
chemical reactants provided by the source gasses are controlled and
the system parameters are set so that the depositing atoms arrive
at the deposition surface of the semiconductor substrate with
sufficient energy to move around on the surface and orient
themselves to the crystal arrangement of the atoms of the
deposition surface. Therefore, an epitaxial semiconductor material
has the same crystalline characteristics as the deposition surface
on which it is formed. For example, an epitaxial semiconductor
material deposited on a {100} crystal surface will take on a {100}
orientation. In some embodiments, epitaxial growth and/or
deposition processes are selective to forming on semiconductor
surface, and do not deposit material on dielectric surfaces, such
as silicon oxide or silicon nitride surfaces. Therefore, in some
embodiments, because the epitaxially grown III-V fin structures 40
are not formed on dielectric structures, such as the dielectric cap
layer 30, or the dielectric layer that is present on the at least
one first gate structure 15, the epitaxially grown III-V fin
structures 40 are selectively deposited on the sidewalls of the
mandrel structure 20. The sidewalls of the mandrel structure 20 are
composed of a semiconductor material, such as germanium or silicon
germanium.
[0035] Examples of various epitaxial growth process apparatuses
that are suitable for use with the present disclosure include,
e.g., rapid thermal chemical vapor deposition (RTCVD), low-energy
plasma deposition (LEPD), ultra-high vacuum chemical vapor
deposition (UHVCVD), atmospheric pressure chemical vapor deposition
(APCVD) and molecular beam epitaxy (MBE). The temperature for
epitaxial deposition process for forming the III-V fin structures
40 typically range from 550.degree. C. to 900.degree. C. Although
higher temperature typically results in faster deposition, the
faster deposition may result in crystal defects and film
cracking.
[0036] In one embodiment, each of the III-V fin structures 40 may
have a width W3 ranging from 2 nm to 30 nm. In another embodiment,
each of the III-V fin structures 40 may have a width W3 ranging
from 5 nm to 15 nm.
[0037] FIG. 5 depicts one embodiment of removing the mandrel
structure 20. In one embodiment, the mandrel structure 20 is
removed by an etch that is selective to the III-V fin structures
40. The etch for removing the mandrel structure 20 may also be
selective to the at least one first gate structure 15. In some
examples, the dielectric cap layer 30 and the dielectric layer that
is present on the at least one first gate structure 15 can be
removed before removing the mandrel structure 20. In one
embodiment, the etch process for removing the mandrel structure 20
may be an anisotropic etch, such as reactive ion etch (RIE), or the
etch process may be an isotropic etch, such as a wet chemical etch.
In one example, a wet etch composed of H.sub.3PO.sub.4 may be used
to remove a dielectric cap layer 30 composed of silicon nitride,
and a wet etch composed of NH.sub.4/H.sub.2O.sub.2 may be used to
remove a mandrel structure 20 composed of germanium. In one
embodiment, the process of removing the mandrel structure 20 and
the dielectric cap layer 30 includes patterning a photoresist layer
to cover the region of the substrate 5 that corresponds to the
p-type semiconductor devices, and removing the dielectric cap layer
30 with a wet etch of hydrofluoric (HF) acid that is selective to
oxide or a reactive ion etch process. Thereafter, the patterned
photoresist layer is removed from the region of the substrate
corresponding to the p-type semiconductor devices and another
patterned photoresist layer is formed over the portion of the
substrate corresponding to the n-type semiconductor devices, in
which at least the mandrel structure 20 is exposed. The exposed
mandrel structure 20 is then removed using a selective wet etch or
plasma etch, such as XeF.sub.2.
[0038] FIG. 6 depicts forming a second gate structure 45 on the
III-V fin structures 40. In one embodiment, the second gate
structure 45 includes at least one second gate dielectric layer 43
and at least one second gate conductor layer 44. The at least one
second gate dielectric layer 43 is typically formed on the channel
portion of the III-V fin structure 40. The at least one second gate
dielectric layer 43 of the second gate structure 45 may be composed
of any dielectric material including oxides, nitrides and
oxynitrides. In one embodiment, the at least one second gate
dielectric layer 43 may be provided by a high-k dielectric
material. In one embodiment, the at least one second gate
dielectric layer 43 is composed of a high-k oxide such as, for
example, HfO.sub.2, ZrO.sub.2, Al.sub.2O.sub.3, TiO.sub.2,
La.sub.2O.sub.3, SrTiO.sub.3, LaAlO.sub.3, Y.sub.2O.sub.3 and
mixtures thereof. Other examples of high-k dielectric materials for
the at least one second gate dielectric layer 43 include hafnium
silicate, hafnium silicon oxynitride or combinations thereof. In
one embodiment, the at least one second gate dielectric layer 43
may be deposited by chemical vapor deposition (CVD). Variations of
CVD processes suitable for depositing the at least one second gate
dielectric layer 43 include, but are not limited to, APCVD, LPCVD,
PECVD, MOCVD, ALD, and combinations thereof. In one embodiment, the
thickness of the at least one second gate dielectric layer 43 is
greater than 0.8 nm. More typically, the at least one second gate
dielectric layer 43 has a thickness ranging from about 1.0 nm to
about 6.0 nm.
[0039] The at least one second gate conductor layer 44 is formed on
the at least one second gate dielectric layer 43. The at least one
second gate conductor layer 44 may be formed by a deposition
process, such as CVD, plasma-assisted CVD, plating, and/or
sputtering, followed by planarization. In one embodiment, the at
least one second gate conductor layer 44 is composed of metal or a
doped semiconductor. Examples of metals that may be employed for
the at least one second gate conductor layer 44 may include, but is
not limited to, W, Ni, Ti, Mo, Ta, Cu, Pt, Ag, Au, Ru, Ir, Rh, and
Re, Al, TiN, WN, TaN, TiAlN, TaAlN, and alloys thereof. One example
of a doped semiconductor that is suitable for the at least one
second gate conductor layer 44 is doped polysilicon.
[0040] In some embodiments, in which the first conductivity finFET
that is formed in the second device region of the substrate 5 is an
n-type finFET, the at least one second gate conductor layer 44 may
include a metal that is an n-type work function metal layer. As
used herein, an "n-type work function metal layer" is a metal layer
that effectuates an n-type threshold voltage shift. "N-type
threshold voltage shift" as used herein means a shift in the Fermi
energy of an n-type semiconductor device towards a conduction band
of silicon in a silicon-containing substrate of the n-type
semiconductor device. The "conduction band" is the lowest lying
electron energy band of the doped material that is not completely
filled with electrons. In one embodiment, the work function of the
n-type work function metal layer ranges from 4.1 eV to 4.3 eV. In
one embodiment, the n-type work function metal layer is composed of
at least one of TiAl, TanN, TiN, HfN, HfSi, or combinations
thereof. The n-type work function metal layer can be deposited
using chemical vapor deposition (CVD), atomic layer deposition
(ALD), sputtering or plating. In one embodiment, the n-type work
function metal layer is composed of titanium aluminum (TiAl) and is
deposited using sputtering. Examples of sputtering apparatus that
may be suitable for depositing the n-type work function metal layer
include DC diode type systems, radio frequency (RF) sputtering,
magnetron sputtering, and ionized metal plasma (IMP) sputtering. In
one example, an n-type work function metal layer composed of TiN is
sputtered from a solid titanium target, in which the nitrogen
content of the metal nitride layer is introduced by a nitrogen gas.
In another example, an n-type work function metal layer composed of
TiN is sputtered from a solid target comprised of titanium and
nitrogen. In addition to physical vapor deposition (PVD)
techniques, the n-type work function metal layer may also be formed
using chemical vapor deposition (CVD) and atomic layer deposition
(ALD). The at least one second gate structure 44 may be formed
using deposition, photolithography and etch processes.
[0041] Following the formation of the second gate structure 45,
source regions 50a, 50b and drain regions 55a, 55b may be formed on
the germanium containing fin structures 10 and the III-V fin
structures 40. In some embodiments, the process sequence for
forming the source regions 50a, 50b and drain regions 55a, 55b
includes forming a spacer 16 on a sidewall of the gate structure
15, 45, and forming the source regions 50a, 50b and drain regions
55a, 55b on opposing sides of the gate structure 15, 45. In some
examples, the exposed portions of the germanium containing fin
structures 20 and the exposed portions of the III-V fin structures
40 may be doped to provide source and drain extension regions. The
source and drain extension regions formed in the germanium
containing fin structures 10 may be p-type doped to provide a
p-type conductivity fin field effect transistor. The source and
drain extension regions to the III-V fin structures 40 may be
n-type doped to provide an n-type conductivity fin field effect
transistor.
[0042] Following the formation of the source and drain extension
regions, epitaxially formed source regions 50a, 50b and drain
regions 55a, 55b may be formed on the germanium containing fin
structures 10 and the III-V fin structures 40. The epitaxially
formed source regions 50a, 50b and drain regions 55a, 55b have a
conductivity that is typically similar to the conductivity of the
source and drain extension regions. For example, the epitaxially
formed source regions 50a and drain regions 55a that are formed on
the germanium containing fin structure 10 may be doped to a p-type
conductivity to provide a p-type finFET device. The epitaxially
formed source regions 50b and drain regions 55b that are formed on
the III-V fin structure 40 may be doped to an n-type conductivity
to provide an n-type finFET device.
[0043] FIGS. 1-6B depict a gate first process. In another
embodiment, the process sequence for forming finFET devices
including the germanium containing fin structures 10 and the III-V
fin structures 40 includes a gate last process sequence, which is
not depicted in the supplied figures. A gate last process includes
forming a replacement gate structure on the channel portion of the
fin structures, e.g., germanium containing fin structures 10 and
III-V fin structures 40, forming a spacer on the sidewall of the
replacement gate structure, forming source and drain regions on
opposing sides of the replacement gate structure, removing the
replacement gate structure, and forming a functional gate structure
in the space once occupied by the replacement gate structure. The
replacement gate structure can include sacrificial material that
defines the geometry of a later formed functional gate structure
that functions to switch the semiconductor device from an "on" to
"off" state, and vice versa. A process sequence employing a
replacement gate structure may be referred to as a "gate last"
process sequence. Both gate first and gate last process sequences
are applicable to the present disclosure.
[0044] In another aspect, the present disclosure provides a
semiconductor device that includes a substrate 5 having a first
device region and a second device region. In one embodiment, a
p-type fin field effect transistor 100a is present in the first
device region. The p-type fin field effect transistor 100a includes
a first fin structure comprised of a germanium containing material,
i.e., germanium containing fin structure 10. In one embodiment, an
n-type fin field effect transistor is simultaneously present in the
second device region. The n-type fin field effect transistor
includes a second fin structure comprised of III-V semiconductor
material, i.e., III-V fin structure 40.
[0045] While the present disclosure has been particularly shown and
described with respect to preferred embodiments thereof, it will be
understood by those skilled in the art that the foregoing and other
changes in forms and details may be made without departing from the
spirit and scope of the present invention. It is therefore intended
that the present invention not be limited to the exact forms and
details described and illustrated, but fall within the scope of the
appended claims.
* * * * *