U.S. patent application number 15/893672 was filed with the patent office on 2019-08-15 for method for forming semiconductor structure.
The applicant listed for this patent is UNITED MICROELECTRONICS CORP.. Invention is credited to Chun-Lung Chen, Kai-Teng Cheng, Wei-Hao Huang, Kun-Yuan Liao, Chun-Hsien Lin, Chia-Lin Lu.
Application Number | 20190252259 15/893672 |
Document ID | / |
Family ID | 67542376 |
Filed Date | 2019-08-15 |
United States Patent
Application |
20190252259 |
Kind Code |
A1 |
Lu; Chia-Lin ; et
al. |
August 15, 2019 |
METHOD FOR FORMING SEMICONDUCTOR STRUCTURE
Abstract
The present invention provides a method for forming a
semiconductor structure. The method including: Firstly, a substrate
is provided, a first region and a second region are defined
thereon, next, a gate dielectric layer and a work function metal
layer are sequentially formed on the substrate within the first
region and within the second region. Afterwards, a dielectric layer
is formed on the work function metal layer within the second
region, a hydrogen gas treatment is then performed on the
substrate, and the work function metal layer is removed within the
first region.
Inventors: |
Lu; Chia-Lin; (Taoyuan City,
TW) ; Chen; Chun-Lung; (Tainan City, TW) ;
Liao; Kun-Yuan; (Hsin-Chu City, TW) ; Lin;
Chun-Hsien; (Tainan City, TW) ; Huang; Wei-Hao;
(New Taipei City, TW) ; Cheng; Kai-Teng;
(Kaohsiung City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNITED MICROELECTRONICS CORP. |
Hsin-Chu City |
|
TW |
|
|
Family ID: |
67542376 |
Appl. No.: |
15/893672 |
Filed: |
February 11, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/28185 20130101;
H01L 21/3212 20130101; H01L 21/28088 20130101; H01L 27/092
20130101; H01L 21/823462 20130101; H01L 21/82345 20130101; H01L
21/3003 20130101; H01L 21/28176 20130101; H01L 21/823842
20130101 |
International
Class: |
H01L 21/8234 20060101
H01L021/8234; H01L 21/30 20060101 H01L021/30; H01L 21/28 20060101
H01L021/28; H01L 21/321 20060101 H01L021/321 |
Claims
1. A method for forming a semiconductor structure, comprising:
providing a substrate, a first region and a second region are
defined thereon; forming a gate dielectric layer and a work
function metal layer sequentially on the substrate within the first
region and within the second region; performing a hydrogen gas
treatment on the substrate; and forming a dielectric layer on the
work function metal layer within the second region; removing the
work function metal layer within the first region.
2. The method of claim 1, wherein the hydrogen gas treatment is
performed before the dielectric layer is formed.
3. The method of claim 1, wherein the hydrogen gas treatment is
performed after the dielectric layer is formed.
4. The method of claim 1, wherein the hydrogen gas treatment is
performed with a nitrogen gas treatment simultaneously.
5. The method of claim 1, wherein a temperature in the hydrogen gas
treatment is between 25.degree. C.-500.degree. C.
6. The method of claim 1, wherein the step for removing the work
function metal layer within the first region does not remove the
work function metal layer within the second region.
7. The method of claim 1, further comprising forming at least two
trenches within the first region and within the second region
respectively, wherein the gate dielectric layer and the work
function metal layer are disposed in the trenches.
8. The method of claim 1, wherein when the hydrogen gas treatment
is performed, the work function metal layer still covers on the
gate dielectric layer.
9. The method of claim 1, wherein the gate dielectric layer
comprises hafnium oxide (HfO.sub.2), hafnium silicon oxide
(HfSiO.sub.4), hafnium silicon oxynitride (HfSiON), aluminum oxide
(Al.sub.2O.sub.3), lanthanum oxide (La.sub.2O.sub.3), tantalum
oxide (Ta.sub.2O.sub.5), yttrium oxide (Y.sub.2O.sub.3), zirconium
oxide (ZrO.sub.2), strontium titanate oxide (SrTiO.sub.3),
zirconium silicon oxide (ZrSiO.sub.4), hafnium zirconium oxide
(HfZrO.sub.4), strontium bismuth tantalate (SrBi.sub.2Ta2O.sub.9,
SBT), lead zirconate titanate (PbZrxTi.sub.1-xO.sub.3, PZT), barium
strontium titanate (BaxSr.sub.1-xTiO.sub.3, BST) and a combination
thereof.
10. The method of claim 1, wherein the work function metal layer
comprises titanium nitride (TiN) and tantalum nitride (TaN).
11. A method for forming a semiconductor structure, comprising:
providing a substrate having a first region and a second region
defined thereon; forming a gate dielectric layer on the substrate
within the first region and within the second region; forming a
first metal layer on the gate dielectric layer within the first
region and within the second region; forming a second metal layer
on the gate dielectric layer within the first region and within the
second region; performing a hydrogen gas treatment on the
substrate; forming a dielectric layer on the second metal layer
within the second region; and removing the second metal layer
within the first region.
12. The method of claim 11, further comprising removing the
dielectric layer from the substrate after the step of removing the
second metal layer within the first region.
13. The method of claim 12, further comprising forming a third
metal layer within the first region and within the second
region.
14. The method of claim 12, further comprising forming a filling
metal layer within the first region and within the second
region.
15. The method of claim 14, further comprising performing a
chemical mechanical polishing (CMP) process on the filling metal
layer.
16. The method of claim 11, wherein the hydrogen gas treatment is
performed after the step of forming a first metal layer on the gate
dielectric layer.
17. The method of claim 11, wherein the hydrogen gas treatment is
performed before the dielectric layer is formed.
18. The method of claim 11, wherein the hydrogen gas treatment is
performed after the dielectric layer is formed.
19. The method of claim 11, wherein the hydrogen gas treatment is
performed after removing the second metal layer within the first
region.
20. The method of claim 11, wherein the first metal layer is a
bottom barrier metal layer and the second metal layer is a work
function metal layer, and the first metal layer still covers on the
gate dielectric layer after removing the second metal layer within
the first region.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The invention relates to a manufacturing method for a
semiconductor structure, and more particularly, to a manufacturing
method for a semiconductor structure with performing an additional
gas treatment to improve the reliability the semiconductor
structure.
2. Description of the Prior Art
[0002] In the semiconductor industry, Moore's law states that the
number of transistors on a chip doubles approximately every two
years. These exponential performance gains present a challenge to
the semiconductor manufacturing industry, along with the dual
challenges of promoting power savings and providing cooling
efficiency. The industry addresses these challenges in multiple
ways. Selecting the gate dielectric and gate electrode are critical
choices in enabling device scaling, and compatibility with CMOS
technology. Two main approaches have emerged in high-k and metal
gate (HKMG) integration: gate-first and gate-last. Gate-last is
also called replacement metal gate (RMG) where the gate electrode
is deposited after S/D junctions are formed and the high-k gate
dielectric is deposited at the beginning of the process (high-k
first).
[0003] A high-k first gate-last process is when the high-k
dielectric is deposited first and the metal is deposited last
(gate-last method). Gate-last is often referred to as the
replacement gate option. "First" and "last" gale denotes whether
the metal gate electrode is deposited before or after the high
temperature anneal process. Typically, reliability of high-k gate
stacks improve as a result of dopant activation anneal at
temperatures around 1000.degree. C., which is built in for
gate-first or high-k first gate-last processes. The high-k last
gate-last (replacement gate) process, however, lacks such built--in
high temperature treatment, and thus reliability is a big
challenge.
SUMMARY OF THE INVENTION
[0004] The present invention provides a method for forming a
semiconductor structure. The method including: Firstly, a substrate
is provided, a first region and a second region are defined
thereon, next, a gate dielectric layer and a work function metal
layer are sequentially formed on the substrate within the first
region and within the second region. Afterwards, a dielectric layer
is formed on the work function metal layer within the second
region, a hydrogen gas treatment is then performed on the
substrate, and the work function metal layer is removed within the
first region.
[0005] The present invention provides a method for forming
semiconductor structure. A gas treatment is additional performed on
the substrate, such as a hydrogen gas treatment or a hydrogen and
nitrogen gas combining treatment, so as to increase the TDBB (time
dependent dielectric breakdown) and the reliability of the gate
dielectric layer (high-k layer) and the work function metal layer,
thereby improving the overall performance of the semiconductor
device.
[0006] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGS. 1-7 are drawings illustrating a manufacturing method
for semiconductor structure provided by a first preferred
embodiment of the present invention.
[0008] FIG. 8 is the drawing illustrating a manufacturing method
for semiconductor structure provided by a second preferred
embodiment of the present invention.
[0009] FIG. 9 shows a flowchart for forming a semiconductor
structure according to the first embodiment of the present
invention.
[0010] FIG. 10 shows a flow chart for forming a semiconductor
structure according to another embodiment of the present
invention.
DETAILED DESCRIPTION
[0011] To provide a better understanding of the present invention
to users skilled in the technology of the present invention,
preferred embodiments are detailed as follows. The preferred
embodiments of the present invention are illustrated in the
accompanying drawings with numbered elements to clarify the
contents and the effects to be achieved.
[0012] Please note that the figures are only for illustration and
the figures may not be to scale. The scale may be further modified
according to different design considerations. When referring to the
words "up" or "down" that describe the relationship between
components in the text, it is well known in the art and should be
clearly understood that these words refer to relative positions
that can be inverted to obtain a similar structure, and these
structures should therefore not be precluded from the scope of the
claims in the present invention.
[0013] Please refer to FIGS. 1-7, which are drawings illustrating a
manufacturing method for semiconductor structure provided by a
first preferred embodiment of the present invention. As shown in
FIG. 1, the preferred embodiment first provides a substrate 100
such as silicon substrate, silicon-containing substrate, or
silicon-on-insulator (SOI) substrate. The substrate 100 includes a
first semiconductor device 101 and a second semiconductor device
102 formed thereon. The first semiconductor device 101 is disposed
within a first region 110, and the second semiconductor device 102
is disposed within a second region 112. A shallow trench isolation
(STI) 113 is formed in the substrate 100 between the first
semiconductor device 101 and the second semiconductor device 102
for providing electrical isolation. The first semiconductor device
101 includes a first conductivity type, the second semiconductor
device 102 includes a second conductivity type, and the first
conductivity type and the second conductivity type are
complementary. In the preferred embodiment, the first conductivity
type is p-type and the second conductivity type is n-type.
[0014] Please refer to FIG. 1. The first semiconductor device 101
and the second semiconductor device 102 respectively include a
dielectric layer (not shown) and a dummy gate (not shown). The
dielectric layer can be a conventional silicon oxide (SiO.sub.2)
layer and the dummy gate can include a polysilicon layer.
Furthermore, the first semiconductor device 101 and the second
semiconductor device 102 respectively include first lightly doped
drains (LDDs) 120 and second LDDs 122, a spacer 124, a first
source/drain 130 and a second source/drain 132. Additionally,
salicides (not shown) may be respectively formed on the first
source/drain 130 and the second source/drain 132. After forming the
first semiconductor device 101 and the second semiconductor device
102, a contact etch stop layer (CESL) 140 and an inter-layer
dielectric (ILD) layer 142 are selectively formed in sequence.
Since the steps and material choices for the abovementioned
elements are well-known to those skilled in the art, those details
are omitted herein in the interest of brevity. Furthermore,
selective strain scheme (SSS) can be used in the preferred
embodiment. For example, a selective epitaxial growth (SEG) method
can be used to form the first source/drain 130 and the second
source/drain 132.
[0015] Please still refer to FIG. 1. After forming the CESL 140 and
the ILD layer 142, a planarization process is performed to remove a
portion of the ILD layer 142 and a portion of the CESL 140 to
expose the dummy gates of the first semiconductor device 101 and
the second semiconductor device 102. Then, a suitable etching
process is performed to remove the dummy gates of the first
semiconductor device 101 and the second semiconductor device 102,
and thus a first gate trench 150 and a second gate trench 152 are
simultaneously formed in the first semiconductor device 101 and the
second semiconductor device 102, respectively. The dielectric
layers or the substrate 100 are respectively exposed in bottoms of
the first gate trench 150 and the second gate trench 152.
[0016] Next, an interfacial layer 103 is optionally formed on the
substrate 10, and afterwards, a high-k dielectric layer 104 and a
first bottom barrier layer 105 are sequentially formed on the
substrate 100. The high-k dielectric layer 104 can include high-k
material such as rare earth metal oxide. The high-k dielectric
layer 104 can include material selected from the group consisting
of hafnium oxide (HfO.sub.2), hafnium silicon oxide (HfSiO.sub.4),
hafnium silicon oxynitride (HfSiON), aluminum oxide
(Al.sub.2O.sub.3), lanthanum oxide (La.sub.2O.sub.3), tantalum
oxide (Ta.sub.2O.sub.5), yttrium oxide (Y.sub.2O.sub.3), zirconium
oxide (ZrO.sub.2), strontium titanate oxide (SrTiO.sub.3),
zirconium silicon oxide (ZrSiO.sub.4), hafnium zirconium oxide
(HfZrO.sub.4), strontium bismuth tantalate,
(SrBi.sub.2Ta.sub.2O.sub.9, SBT), lead zirconate titanate
(PbZrxTi.sub.1-xO.sub.3, PZT), and barium strontium titanate
(BaxSr1-xTiO.sub.3, BST). In the preferred embodiment, the bottom
barrier layer may be a single layer structure or a multiple layer
structure, such as comprising the first bottom barrier layer 105
and the second bottom barrier layer 106, wherein the first bottom
barrier layer 105 can include titanium nitride (TiN) and the second
bottom barrier layer 106 can include tantalum nitride (TaN), but
not limited to this.
[0017] After the high-k dielectric layer 104, the first bottom
barrier layer 105 and the second bottom barrier layer 106 are
formed, a first work function metal layer 160 is formed in the
first gate trench 150 and the second gate trench 152. The first
work function metal layer 160 is a p-type work function metal layer
and exemplarily includes titanium nitride (TiN), tantalum nitride
(TaN), titanium carbide (TiC), tantalum carbide (TaC), tungsten
carbide (WC), or aluminum titanium nitride (TiAlN), but not limited
to this. Or the first work function metal layer 160 includes an
n-type work function metal layer such as titanium aluminide (TiAl),
zirconium aluminide (ZrAl), tungsten aluminide (WAl), tantalum
aluminide (TaAl), or hafnium aluminide (HfAl), but not limited to
this. In addition, the first work function metal layer 160 can be a
single-layered structure or a multi-layered structure.
[0018] Afterwards, as shown in FIG. 2, a gas treatment P1 is
performed on the substrate 100. In the present invention, the gas
treatment P1 includes a hydrogen gas treatment or a
hydrogen/nitrogen gas treatment, which is the gas treatment
combining the hydrogen gas and the nitrogen gas, in other words,
the hydrogen gas treatment and the nitrogen gas treatment are
performed simultaneously. Preferably, the temperature in the gas
treatment P1 of the present invention is between 25-500.degree. C.,
the pressure of the gas treatment P1 of the present invention is
between 0-1500 mtorr (millitorr), the flow rate of the hydrogen gas
in the gas treatment P1 of the present invention is between 5-10000
sccm (standard cubic centimeter per minute), and the flow rate of
the nitrogen gas in the gas treatment P1 of the present invention
is between 0-5000 sccm, but not limited thereto. The parameters
mentioned above can be adjusted according to actual requirements.
The purpose for performing the gas treatment P1 is to improve the
reliability of the semiconductor device. More precisely, the
applicant found that after the gas treatment P1 is performed, the
reliability of the high-k dielectric layer 104 and the first work
function metal layer 160 are increased, therefore the performance
of the overall device can be improved. For example, by the
applicant's experiment, compared with the process without
performing the gas treatment P1, the time dependent dielectric
breakdown (TDDB) of the completed semiconductor device of the
present invention is increased, and the maximum voltage of the hot
carrier injection (HCI) is about 60 mV.
[0019] Next, as shown in FIG. 3, a dielectric layer 170 and a
photoresist layer 172 are formed, the dielectric layer 170 is
formed in the first gate trench 150 and the second gate trench 152,
and the photoresist layer 172 is only disposed within the second
region 112. Afterwards, as shown in FIG. 4, an etching step P2 is
performed to remove parts of the dielectric layer 170 within the
first region 110, so as to expose the first work function metal
layer 160 in the first region 110. Next, as shown in FIG. 5, an
etching step P3 is performed to remove parts of the first work
function metal layer 160 within the first region 110. In other
words, after the etching step P3 is performed, the first work
function metal layer 160 is only disposed within the second region
112.
[0020] As shown in FIG. 6, after the first work function metal
layer 160 is partially removed, a CVD process or a PVD process is
then performed to form a second work function metal layer 162 on
the substrate 100. In this embodiment, the second work function
metal layer 162 includes an n-type work function metal layer such
as titanium aluminide (TiAl), zirconium aluminide (ZrAl), tungsten
aluminide (WAl), tantalum aluminide (TaAl), or hafnium aluminide
(HfAl), but not limited to this. Or the second work function metal
layer 162 is a p-type work function metal layer and exemplarily
includes TiN, TaN, titanium carbide (TiC), tantalum carbide (TaC),
tungsten carbide (WC), or aluminum titanium nitride (TiAlN), but
not limited to this. Additionally, the second work function metal
layer 162 can be a single-layered structure or a multi-layered
structure.
[0021] Thereafter, a filling metal layer 164 is formed in both of
the first gate trench 150 and the second gate trench 152.
Additionally, a top barrier layer 163 is preferably formed between
the second work function metal layer 162 and the filling metal
layer 164. The top barrier layer 163 can include TiN, but not
limited to this. The filling metal layer 164 is formed to fill up
the first gate trench 150 and the second gate trench 152. The
filling metal layer 164 includes materials with low resistance and
superior gap-filling characteristic, such as W, Al, TiAl, or
titanium aluminum oxide (TiAlO), but not limited to this.
[0022] It is noteworthy that in the present invention, the first
work function metal layer 160 and the first semiconductor device
101 preferably have the same conductivity type. Take the embodiment
mentioned above as an example. If the first semiconductor device
101 is p-type, and the second semiconductor device 102 is n-type,
the first work function metal layer 160 is a p-type work function
metal layer, and the second work function metal layer 162 is a
n-type work function metal layer. However, in another embodiment of
the present invention, if the first semiconductor device 101 is
n-type, and the second semiconductor device 102 is p-type, the
first work function metal layer 160 is a n-type work function metal
layer, and the second work function metal layer 162 is a p-type
work function metal layer. In this case, since the second work
function metal layer 162 is a p-type work function metal layer, and
the material of the second work function metal layer 162 may be the
same as the material of the top barrier layer 163, such as TiN, the
top barrier layer 163 is preferably omitted in that situation.
Preferably, in the present invention, the first semiconductor
device 101 is p-type, and the second semiconductor device 102 is
n-type.
[0023] Subsequently, as shown in FIG. 7, a planarization process,
such as a chemical mechanical polishing (CMP) process is performed
to remove the unnecessary filling metal layer 164 and even the
high-k dielectric layer 104 exposed on the ILD layer 142.
Consequently, a first metal gate and a second metal gate are
obtained. In addition, the ILD layer 140 and the CESL 142 can be
selectively removed and sequentially reformed on the substrate 100
for improving performance of the semiconductor devices 101/102 in
the preferred embodiment. Since the abovementioned CMP process is
well-known to those skilled in the art, those details are omitted
in the interest of brevity.
[0024] In another embodiment of the present invention, please refer
to FIG. 8, which is the drawing illustrating a manufacturing method
for semiconductor structure provided by a second preferred
embodiment of the present invention. In this embodiment, the
sequence for forming the gas treatment P1 is different from that of
the first preferred embodiment. More precisely, after the first
work function metal layer 160 is formed in the first gate trench
150 and a second gate trench 152 (please refer to FIG. 1 mentioned
above), the gas treatment P1 hadn't been performed yet, and as
shown in FIG. 8, the gas treatment P1 is performed after the
dielectric layer 170 within the first region 110 which is partially
removed. Afterwards, the first work function metal layer 160 within
the first region 110 is then removed (please refer to FIG. 5
mentioned above), the following steps are same as that of the first
preferred embodiment mentioned above. It should also be within the
scope of the present invention. Except for the feature mentioned
above, the other components, material properties, and manufacturing
method of this embodiment are similar to the first preferred
embodiment detailed above and will not be redundantly
described.
[0025] FIG. 9 shows a flow chart for forming a semiconductor
structure according to the first embodiment of the present
invention. As shown in FIG. 9, the method including: step 1001:
providing a substrate 100, a first region 110 and a second region
112 are defined thereon; step 1002:forming a gate dielectric layer
(high-k dielectric layer) 104 and a work function metal layer 160
sequentially on the substrate 100 within the first region 110 and
within the second region 112 (please refer to FIG. 1); step 1003:
performing a hydrogen gas treatment P1 on the substrate 100 (please
refer to FIG. 2); step 1004: forming a dielectric layer 170 on the
work function metal layer 160 within the second region 112 (please
refer to FIG. 4); and step 1005: removing the work function metal
layer 160 within the first region 110 (please refer to FIG. 5).
[0026] In another embodiment of the present invention, the gas
treatment P1 can be performed after the first work function metal
layer 160 and the second work function metal layer 162 are formed.
In other words, the step shown in FIG. 2 is skipped, and the gas
treatment P1 can be performed after the second work function metal
layer 162 is formed. FIG. 10 shows a flow chart for forming a
semiconductor structure according to another embodiment of the
present invention. As shown in FIG. 10, the method including: step
2001: providing a substrate 100, a first region 110 and a second
region 112 are defined thereon; step 2002:forming a gate dielectric
layer (high-k dielectric layer) 104 on the substrate 100 within the
first region 110 and within the second region 112 (please refer to
FIG. 1); step 2003: forming a first work function metal layer 160
on the gate dielectric layer 104 within the first region 110 and
within the second region 112; step 2004: forming a second work
function metal layer 162 on the gate dielectric layer 104 within
the first region 110 and within the second region 112; step 2005:
performing a gas treatment P1 on the substrate 100; step 2006:
forming a dielectric layer 170 on the second work function metal
layer 162 within the second region 112; and step 2007:removing the
second work function metal layer 162 within the first region 110.
Except for the features mentioned above, the other components,
material properties, and manufacturing method of this embodiment
are similar to the first preferred embodiment detailed above and
will not be redundantly described.
[0027] Besides, in another case, the gas treatment P1 can be
performed after the dielectric layer 170 within the second region
112 is formed (for example, the step 2005 shown in FIG. 10 can be
performed after the step 2006), or can be performed after the
second work function metal layer 162 within the first region 110 is
removed (for example, the step 2005 shown in FIG. 10 can be
performed after the step 2007). It should also be within the scope
of the present invention.
[0028] In summary, the present invention provides a method for
forming semiconductor structure. A gas treatment is additional
performed on the substrate, such as a hydrogen gas treatment or a
hydrogen and nitrogen gas combining treatment, so as to increase
the TDBB (time dependent dielectric breakdown) and the reliability
of the gate dielectric layer (high-k layer) and the work function
metal layer, thereby improving the overall performance of the
semiconductor device.
[0029] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *