U.S. patent application number 14/507182 was filed with the patent office on 2015-02-26 for late in-situ doped sige junctions for pmos devices on 28 nm low power/high performance technologies using a silicon oxide encapsulation, early halo and extension implantations.
The applicant listed for this patent is GLOBALFOUNDRIES Singapore Pte. Ltd.. Invention is credited to Stefan FLACHOWSKY, Jan HOENTSCHEL, Shiang Yang ONG, Thilo SCHEIPER.
Application Number | 20150054072 14/507182 |
Document ID | / |
Family ID | 49669184 |
Filed Date | 2015-02-26 |
United States Patent
Application |
20150054072 |
Kind Code |
A1 |
HOENTSCHEL; Jan ; et
al. |
February 26, 2015 |
LATE IN-SITU DOPED SIGE JUNCTIONS FOR PMOS DEVICES ON 28 NM LOW
POWER/HIGH PERFORMANCE TECHNOLOGIES USING A SILICON OXIDE
ENCAPSULATION, EARLY HALO AND EXTENSION IMPLANTATIONS
Abstract
A HKMG device with PMOS eSiGe source/drain regions is provided.
Embodiments include forming first and second HKMG gate stacks on a
substrate, forming a nitride liner and oxide spacers on each side
of each HKMG gate stack, performing halo/extension implants at each
side of each HKMG gate stack, forming an oxide liner and nitride
spacers on the oxide spacers of each HKMG gate stack, forming deep
source/drain regions at opposite sides of the second HKMG gate
stack, forming an oxide hardmask over the second HKMG gate stack,
forming embedded silicon germanium (eSiGe) at opposite sides of the
first HKMG gate stack, and removing the oxide hardmask.
Inventors: |
HOENTSCHEL; Jan; (Dresden,
DE) ; ONG; Shiang Yang; (Dresden, DE) ;
FLACHOWSKY; Stefan; (Dresden, DE) ; SCHEIPER;
Thilo; (Dresden, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GLOBALFOUNDRIES Singapore Pte. Ltd. |
Singapore |
|
SG |
|
|
Family ID: |
49669184 |
Appl. No.: |
14/507182 |
Filed: |
October 6, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13482393 |
May 29, 2012 |
|
|
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14507182 |
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Current U.S.
Class: |
257/338 ;
257/337 |
Current CPC
Class: |
H01L 27/0922 20130101;
H01L 29/7848 20130101; H01L 21/26513 20130101; H01L 29/1054
20130101; H01L 29/4925 20130101; H01L 29/7834 20130101; H01L
21/823864 20130101; H01L 21/2658 20130101; H01L 29/7833 20130101;
H01L 29/66636 20130101; H01L 29/6656 20130101; H01L 21/823807
20130101; H01L 29/458 20130101; H01L 29/6659 20130101; H01L
21/823814 20130101; H01L 29/0847 20130101; H01L 27/088
20130101 |
Class at
Publication: |
257/338 ;
257/337 |
International
Class: |
H01L 27/092 20060101
H01L027/092; H01L 29/49 20060101 H01L029/49; H01L 29/45 20060101
H01L029/45; H01L 29/10 20060101 H01L029/10; H01L 27/088 20060101
H01L027/088; H01L 29/78 20060101 H01L029/78 |
Claims
1. A device comprising: first and second high-k dielectric metal
gate (HKMG) gate stacks; a nitride liner in direct contact with
first and second oxide spacers on each side of each of the first
and second HKMG gate stacks; halo and extension regions at opposite
sides of each of the first and second HKMG gate stacks; deep
source/drain regions at opposite sides of the second gate HKMG gate
stack; and embedded silicon germanium (eSiGe) at opposite sides of
the first HKMG gate stack.
2. The device according to claim 1, wherein nitride spacers are
formed over the second oxide spacers, and the deep source/drain
regions at opposite sides of the second gate HKMG gate stack formed
using the nitride spacers as a soft mask.
3. The device according to claim 2, wherein the nitride liner and
nitride spacers comprise silicon nitride (SiN).
4. The device according to claim 3, wherein the oxide spacers
comprise silicon dioxide (SiO.sub.2).
5. The device according to claim 1, wherein the eSiGe is doped
in-situ with boron having a graded doping profile.
6. The device according to claim 1, further comprising a silicide
on the eSiGe, the deep source/drain regions, and the first and
second HKMG gate stacks.
7. The device according to claim 1, further comprising a channel
SiGe region below the first HKMG gate stack.
8. The device according to claim 1, wherein each of the first and
second HKMG gate stacks comprises a high-k dielectric, a work
function metal, and polysilicon (poly-Si).
9. The device according to claim 1, wherein the embedded eSiGe is
embedded by forming a cavity and epitaxially growing SiGe in the
cavity.
10. The device according to claim 9, wherein the cavity is formed
by wet etching with tetramethylammonium hydroxide (TMAH).
11. A device comprising: PMOS and NMOS high-k metal gate (HKMG)
gate stacks on a substrate; a first L-shaped liner and first
spacers on each side of each of the PMOS and NMOS HKMG gate stacks,
such that the first L-shaped liner is in direct contact with the
PMOS and NMOS HKMG gate stacks; halo/extension implants at each
side of each of the PMOS and NMOS HKMG gate stacks; a second
L-shaped liner and second spacers on the first spacers of each of
the PMOS and NMOS HKMG gate stacks; deep source/drain regions at
opposite sides of the NMOS HKMG gate stack; embedded silicon
germanium (eSiGe) at opposite sides of the PMOS HKMG gate stack;
and a silicide on the source/drain regions, the eSiGe, and the PMOS
and NMOS HKMG gate stacks.
12. The device according to claim 11, wherein the first L-shaped
liner comprises silicon nitride (SiN).
13. The device according to claim 11, wherein the first spacers
comprise silicon dioxide (SiO2).
14. The device according to claim 11, wherein the second L-shaped
liner comprises silicon dioxide (SiO2).
15. The device according to claim 11, wherein the second spacers
comprise silicon nitride (SiN).
16. The device according to claim 11, wherein the embedded eSiGe is
embedded by forming a cavity and epitaxially growing SiGe in the
cavity.
17. The device according to claim 16, wherein a boron dopant, with
a graded doping profile, is implanted in-situ into the eSiGe
concurrently with the epitaxial growth.
18. The device according to claim 16, wherein the cavity is formed
by wet etching with tetramethylammonium hydroxide (TMAH).
19. The device according to claim 18, wherein the cavity is sigma
shaped.
20. The device according to claim 11, wherein each of the PMOS and
NMOS HKMG gate stacks comprises a high-k dielectric, a work
function metal, and polysilicon (poly-Si).
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This Application is a Divisional of U.S. application Ser.
No. 13/482,393, filed May 29, 2012, the content of which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to high-k metal gate (HKMG)
semiconductor device with embedded silicon germanium (SiGe)
source/drain regions. The present disclosure is particularly
applicable to 28 nanometer (nm) super-low-power (28SLP)
technologies.
BACKGROUND
[0003] In the current mobile/multimedia market, there is a great
need for long standby time, or rather, low leakage products. The
28SLP process was originally designed to meet that need. However,
there is also a demand for higher performance with low power
consumption. The drive for high performance requires high speed
operation of microelectronic components requiring high drive
currents. Typically, the structural and doping parameters tending
to provide a desired increase in drive current adversely impact
leakage current. High-k metal gate (HKMG) electrodes have evolved
for improving the drive current by reducing polysilicon
depletion.
[0004] In modern CMOS technologies, embedded silicon germanium
(SiGe) source/drain areas are standard in PFET devices as they
improve performance by introducing uniaxial strain into the
channel. However, to date the 28SLP process does not include an
embedded source/drain stressor such as SiGe in the p-active
source/drain regions and therefore is lacking in performance due to
lower hole mobility.
[0005] A need therefore exists for methodology enabling fabrication
of an SLP device with high performance by incorporating SiGe into
an HKMG process, and the resulting device.
SUMMARY
[0006] An aspect of the present disclosure is an in-situ-doped late
SiGe (after all implants in the process flow) process flow for
forming a HKMG CMOS device with embedded SiGe (eSiGe) in the
PMOS.
[0007] Another aspect of the present disclosure is a HKMG CMOS
device with embedded SiGe in the PMOS formed by a late SiGe process
flow.
[0008] Additional aspects and other features of the present
disclosure will be set forth in the description which follows and
in part will be apparent to those having ordinary skill in the art
upon examination of the following or may be learned from the
practice of the present disclosure. The advantages of the present
disclosure may be realized and obtained as particularly pointed out
in the appended claims.
[0009] According to the present disclosure, some technical effects
may be achieved in part by a method including: forming first and
second high-k metal gate (HKMG) gate stacks on a substrate; forming
a nitride liner and oxide spacers on each side of each of the first
and second HKMG gate stacks; performing halo/extension implants at
each side of each of the first and second HKMG gate stacks; forming
an oxide liner and nitride spacers on the oxide spacers of each of
the first and second HKMG gate stacks; forming deep source/drain
regions at opposite sides of the second HKMG gate stack; forming an
oxide hardmask over the second HKMG gate stack; forming embedded
silicon germanium (eSiGe) at opposite sides of the first HKMG gate
stack; and removing the hardmask.
[0010] Aspects of the present disclosure include forming the
nitride liner of silicon nitride (SiN); forming the oxide spacers
of SiO.sub.2; and forming the nitride spacers of SiN. Further
aspects include the first and second HKMG gate stacks each
including a high-k dielectric, a work function metal, polysilicon
(poly-Si), and a SiN cap. Other aspects include precleaning prior
to forming the eSiGe; and optimizing the precleaning to protect the
SiO.sub.2 spacers. Another aspect includes forming eSiGe at each
side of the first HKMG gate stack by: forming a cavity by wet
etching with tetramethylammonium hydroxide (TMAH); and epitaxially
growing SiGe in the cavity. Additional aspects include implanting a
boron dopant in-situ into the eSiGe, for example with a graded
doping profile. Further aspects include annealing to activate
implanted dopants after forming the oxide hardmask. Another aspect
includes removing oxide hardmask by wet etching with diluted
hydrofluoric acid (dHF). Other aspects include removing the SiN cap
and nitride spacers after removing the oxide hardmask. Additional
aspects include removing the SiN cap and nitride spacer by a dry or
wet etch process. Further aspects include forming a silicide on the
source/drain regions, the eSiGe, and the first and second HKMG gate
stacks. Another aspect includes forming a channel SiGe region below
the first HKMG gate stack.
[0011] Another aspect of the present disclosure is a device
comprising: first and second high-k dielectric metal gate (HKMG)
gate stacks, each comprising a high-k dielectric, a work function
metal, and polysilicon (poly-Si); a nitride liner and first and
second oxide spacers successively formed on each side of each of
the first and second HKMG gate stacks; halo and extension regions
at opposite sides of each of the first and second HKMG gate stacks
formed prior to the second oxide spacers; deep source/drain regions
at opposite sides of the second gate HKMG gate stack formed after
the second oxide spacers; and embedded silicon germanium (eSiGe) at
opposite sides of the first HKMG gate stack, formed after the deep
source/drain regions using a hardmask over the second gate
stack.
[0012] Aspects include first and second high-k dielectric metal
gate (HKMG) gate stacks, each comprising a high-k dielectric, a
work function metal, and polysilicon (poly-Si); a nitride liner and
first and second oxide spacers successively formed on each side of
each of the first and second HKMG gate stacks; halo and extension
regions at opposite sides of each of the first and second HKMG gate
stacks formed prior to the second oxide spacers; deep source/drain
regions at opposite sides of the second gate HKMG gate stack formed
after the second oxide spacers; and embedded silicon germanium
(eSiGe) at opposite sides of the first HKMG gate stack, formed
after the deep source/drain regions using a hardmask over the
second gate stack. Further aspects include nitride spacers being
formed over the second oxide spacers, and the deep source/drain
regions at opposite sides of the second gate HKMG gate stack being
formed using the nitride spacers as a soft mask. Another aspect
includes the nitride liner and nitride spacers being silicon
nitride (SiN) and the oxide spacers being silicon dioxide
(SiO.sub.2). Additional aspects include the eSiGe being doped
in-situ with boron having a graded doping profile. Other aspects
include a silicide on the eSiGe, the deep source/drain regions, and
the first and second HKMG gate stacks. Another aspect includes a
channel SiGe region below the first HKMG gate stack.
[0013] Another aspect of the present disclosure is a method
including: forming PMOS and NMOS high-k metal gate (HKMG) gate
stacks on a substrate; forming an L-shaped silicon nitride (SiN)
liner and silicon dioxide (SiO.sub.2) spacers on each side of each
of the PMOS and NMOS HKMG gate stacks; performing halo/extension
implants at each side of each of the PMOS and NMOS HKMG gate
stacks; forming an L-shaped SiO.sub.2 liner and SiN spacers on the
SiO.sub.2 spacers of each of the PMOS and NMOS HKMG gate stacks;
implanting deep source/drain regions at opposite sides of the NMOS
HKMG gate stack; forming an SiO.sub.2 hardmask over the NMOS HKMG
gate stack; forming embedded silicon germanium (eSiGe) at opposite
sides of the PMOS HKMG gate stack by: forming a cavity at each side
of the PMOS HKMG gate stack by wet etching with TMAH, epitaxially
growing SiGe in the cavity, and implanting a boron dopant, with a
graded doping profile, in-situ into the eSiGe concurrently with the
epitaxial growth; wet etching the SiO.sub.2 hardmask with diluted
hydrofluoric acid (dHF); dry or wet etching the SiN cap and SiN
spacers; and forming a silicide on the source/drain regions, the
eSiGe, and the PMOS and NMOS HKMG gate stacks.
[0014] Additional aspects and technical effects of the present
disclosure will become readily apparent to those skilled in the art
from the following detailed description wherein embodiments of the
present disclosure are described simply by way of illustration of
the best mode contemplated to carry out the present disclosure. As
will be realized, the present disclosure is capable of other and
different embodiments, and its several details are capable of
modifications in various obvious respects, all without departing
from the present disclosure. Accordingly, the drawings and
description are to be regarded as illustrative in nature, and not
as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present disclosure is illustrated by way of example, and
not by way of limitation, in the figures of the accompanying
drawing and in which like reference numerals refer to similar
elements and in which:
[0016] FIGS. 1A through 1I schematically illustrate a process flow
for forming a semiconductor device with PMOS embedded SiGe
source/drain regions, in accordance with an exemplary
embodiment.
DETAILED DESCRIPTION
[0017] In the following description, for the purposes of
explanation, numerous specific details are set forth in order to
provide a thorough understanding of exemplary embodiments. It
should be apparent, however, that exemplary embodiments may be
practiced without these specific details or with an equivalent
arrangement. In other instances, well-known structures and devices
are shown in block diagram form in order to avoid unnecessarily
obscuring exemplary embodiments. In addition, unless otherwise
indicated, all numbers expressing quantities, ratios, and numerical
properties of ingredients, reaction conditions, and so forth used
in the specification and claims are to be understood as being
modified in all instances by the term "about."
[0018] The present disclosure addresses and solves the current
problem of insufficient encapsulation of the gate first HKMG,
attendant upon forming eSiGe source/drain regions in PMOS devices.
In accordance with embodiments of the present disclosure, a late
SiGe approach is incorporated into an HKMG process, improving
yield, with higher PFET performance. More specifically, a nitride
liner, oxide spacers, an oxide liner, and nitride spacers are
formed to encapsulate the gate during various implantations, an
oxide hardmask is formed over the NMOS gate stack after all
implantations are complete, and eSiGe is epitaxially grown in
cavities formed on opposite sides of the PMOS.
[0019] Methodology in accordance with embodiments of the present
disclosure includes forming first and second high-k metal gate
(HKMG) gate stacks on a substrate, forming a nitride liner and
oxide spacers on each side of each of the first and second HKMG
gate stacks, performing halo/extension implants at each side of
each of the first and second HKMG gate stacks, forming an oxide
liner and nitride spacers on the oxide spacers of each of the first
and second HKMG gate stacks, forming deep source/drain regions at
opposite sides of the second HKMG gate stack, forming an oxide
hardmask over the second HKMG gate stack, forming embedded silicon
germanium (eSiGe) at opposite sides of the first HKMG gate stack,
and removing the hardmask.
[0020] Still other aspects, features, and technical effects will be
readily apparent to those skilled in this art from the following
detailed description, wherein preferred embodiments are shown and
described, simply by way of illustration of the best mode
contemplated. The disclosure is capable of other and different
embodiments, and its several details are capable of modifications
in various obvious respects. Accordingly, the drawings and
description are to be regarded as illustrative in nature, and not
as restrictive.
[0021] FIGS. 1A through 1I illustrate a process flow incorporating
embedded SiGe in the PMOS, in accordance with an exemplary
embodiment of the present disclosure. Adverting to FIG. 1A, a gate
first HKMG stack 101, including high-k dielectric 103, for example
hafnium oxide (HfO.sub.2) or hafnium silicon oxynitride (HfSiON),
work function metal 105, such as titanium nitride (TiN),
poly-silicon (poly-Si) 107, and nitride cap 109, is shown on
silicon substrate 111 for each of NMOS 113 and PMOS 115. PMOS 115
further includes channel SiGe (cSiGe) 117 to a thickness of 5 to 10
nm into substrate 111, below high-k dielectric 103, to adjust the
threshold voltage due to the gate first approach. Using the gate
first approach further requires an encapsulation layer around the
gate stack to protect the HKMG from later process steps such as
cleans and etches. For this purpose, a multilayer deposition (MLD)
silicon nitride (Si.sub.3N.sub.4) layer 119 is blanket deposited
over the entire substrate to a thickness of 3 nm to 6 nm. A low
pressure tetra ethyl ortho silicate (LPTEOS)/high temperature oxide
(HTO) oxide layer 121 is formed over Si.sub.3N.sub.4 MLD layer 119
to a thickness of 5 nm to 10 nm, for forming a spacer zero on each
side of each gate stack.
[0022] As illustrated in FIG. 1B, oxide layer 121 is
anisotropically etched to form SiO.sub.2 spacers (SPO) 123. MLD
Si.sub.3N.sub.4 layer 119 is also etched from the open active
areas. The spacers are used to offset and adjust halo/extension
implants (125/127) in forming halo regions 129 and extension
regions 131, shown in FIG. 1C, for both the NMOS and PMOS, using an
implant mask for each (not shown for illustrative convenience).
Halo regions are formed by implanting a low to medium dose (e.g.,
3.5E13 to 7E13) of arsenic (As), boron (B), or boron fluoride
(BF.sub.2) at a medium energy (for example 35 keV to 50 keV).
Extension regions are formed by implanting a high dose (e.g.
1.1E15) of AS, B, or BF.sub.2 at a low energy (for example 0.7 keV
for B or 4 keV for As).
[0023] Adverting to FIG. 1D, a nitride spacer 133, for example SiN,
is formed on both the NMOS and the PMOS, with an oxide liner 135
underneath to act as an etch stop. Nitride spacers 133 are used as
a soft mask for deep source/drain implants in the NMOS, for forming
deep source/drain regions 137. For example, As, B, or BF.sub.2 may
be implanted at a high dose (e.g., 2E15) and high energy (e.g., 6
keV for B or 20 keV for As).
[0024] Subsequently, as illustrated in FIG. 1E, an oxide layer 139
is deposited to a thickness of 10 nm to 25 nm over NMOS 113. Oxide
layer 139 may be formed over NMOS 113 and PMOS 115, and then
cleared from PMOS 115. The oxide layer acts as a hardmask over NMOS
113. Next a rapid thermal anneal (RTA) is performed to activate the
dopants and anneal all implant damages. The RTA simultaneously
hardens hardmask 139 through trough densification. Alternatively,
the RTA may be performed directly after the n-type deep
source/drain implant, and thus before formation of the oxide
hardmask 139.
[0025] As illustrated in FIG. 1F, a sigma shaped cavity 141 is
formed using tetramethylammonium hydroxide (TMAH) in the substrate
on each side of the PMOS 115 gate stack. Although other shapes are
possible, the sigma shaped cavity 141 allows very close proximities
and therefore maximum stress inside the transistor channel region.
Before further processing, a preclean is performed for, that is
optimized (i.e., not very aggressive) to protect the oxide hardmask
139.
[0026] After the preclean, as illustrated in FIG. 1G, SiGe 143 is
grown in the cavities 141, for example by a low-pressure chemical
vapor deposition (LPCVD) process as an in-situ graded boron doped
deposition for the deep source/drain areas of the PMOS device.
In-situ doping is employed to allow high and uniform doping levels,
which in turn reduces parasitic resistance and contact resistance,
thereby allowing higher drive currents. In addition, the boron
allow the germanium content to be increased, e.g. to greater than
35%, as opposed to 25% for undoped SiGe, which induces higher
stresses and further improves hole mobility enhancement. By doping
the source/drain regions of the PMOS during the epitaxy, a
dedicated source/drain implantation is eliminated, thereby saving
process costs for masks and implantation, reducing cycle time, and
reducing stress relaxation from implant damage. Further, the boron
dopants are activated by the epitaxy, thereby eliminating the need
for an additional anneal. A slight overgrowth helps to form a more
solid encapsulation and margin for subsequent cleans that attack
the active open silicon area. The overgrowth further provides extra
margin for forming a solid salicide, for example nickel silicide
(NiSi), and has better contact resistance.
[0027] As illustrated in FIG. 1H, another cleaning step, e.g. using
a wet etch, for example with diluted hydrofluoric acid (dHF), will
remove oxide hardmask 139 from NMOS 113. Adverting to FIG. 1I, the
wet etch is followed by a dry etch or by an additional wet etch,
for example employing hot phosphoric acid (H.sub.3PO.sub.4), to
remove the nitride caps 109 and nitride spacers 133. As shown, this
leaves an L-shaped oxide spacers 135 exposed.
[0028] Metal, for example nickel (Ni), nickel titanium (NiTi), or
cobalt (Co), may then be deposited over the entire device and
annealed to form a silicide 145 over source/drain regions 137 and
poly-Si 107 (i.e., NiSi, NiTiSi, or CoSi) and over SiGe 143 (i.e.,
NiSiGe, NiTiSiGe, or CoSiGe), to form low resistance areas. The
silicide combined with the SiGe lowers the sheet and contact
resistance, thereby improving performance behavior. The process
flow then continues with conventional middle-of-line (MOL)
processes and contact formation. Alternatively, if L-shaped oxide
spacer 135 is too thin at the time of salicidation, e.g. less than
10 nm, for example because of thinning during a preclean prior to
depositing the nickel, an additional nitride spacer (SiN salicide
protection spacer, not shown for illustrative convenience) must be
formed prior to forming the silicide, to increase the silicide
distance from the channel region. Then the process may continue
with the salicidation as disclosed, and MOL processes and contact
formation.
[0029] The embodiments of the present disclosure can achieve
several technical effects, including improved gate first HKMG
encapsulation, thereby improving yield, lower contact resistance,
lower serial resistance in the PMOS devices, increased carrier
mobility and drive current with lower power in the PMOS devices,
increased performance, and lower manufacturing costs. Devices
formed in accordance with embodiments of the present disclosure
enjoy utility in various industrial applications, e.g.,
microprocessors, smart phones, mobile phones, cellular handsets,
set-top boxes, DVD recorders and players, automotive navigation,
printers and peripherals, networking and telecom equipment, gaming
systems, and digital cameras. The present disclosure therefore
enjoys industrial applicability in any of various types of highly
integrated semiconductor devices, particularly for 32 nm and 28 nm
technologies and beyond.
[0030] In the preceding description, the present disclosure is
described with reference to specifically exemplary embodiments
thereof. It will, however, be evident that various modifications
and changes may be made thereto without departing from the broader
spirit and scope of the present disclosure, as set forth in the
claims. The specification and drawings are, accordingly, to be
regarded as illustrative and not as restrictive. It is understood
that the present disclosure is capable of using various other
combinations and embodiments and is capable of any changes or
modifications within the scope of the inventive concept as
expressed herein.
* * * * *