U.S. patent application number 17/449951 was filed with the patent office on 2022-01-27 for semiconductor structure.
The applicant listed for this patent is NANYA TECHNOLOGY CORPORATION. Invention is credited to Shing-Yih Shih, Mao-Ying Wang, Hung-Mo Wu.
Application Number | 20220028734 17/449951 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-27 |
United States Patent
Application |
20220028734 |
Kind Code |
A1 |
Shih; Shing-Yih ; et
al. |
January 27, 2022 |
SEMICONDUCTOR STRUCTURE
Abstract
A semiconductor structure includes a semiconductor device, a
conductive line, a dielectric layer and a redistribution layer
(RDL). The conductive line is present over the semiconductor
device. The dielectric layer is present over the conductive line.
The RDL includes a conductive structure over the dielectric layer
and a conductive via extending downwards from the conductive
structure and through the dielectric layer. The conductive via
comprises a bottom portion, a top portion, and a tapered portion
between the bottom and top portions, wherein the tapered portion
has a width variation greater than that of the bottom and top
portions.
Inventors: |
Shih; Shing-Yih; (New Taipei
City, TW) ; Wang; Mao-Ying; (New Taipei City, TW)
; Wu; Hung-Mo; (New Taipei City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NANYA TECHNOLOGY CORPORATION |
New Taipei City |
|
TW |
|
|
Appl. No.: |
17/449951 |
Filed: |
October 5, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16439690 |
Jun 12, 2019 |
11189523 |
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17449951 |
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International
Class: |
H01L 21/768 20060101
H01L021/768; H01L 23/31 20060101 H01L023/31; H01L 23/522 20060101
H01L023/522 |
Claims
1. A semiconductor structure, comprising: a semiconductor device; a
conductive line over the semiconductor device; a dielectric layer
over the conductive line; and a redistribution layer (RDL)
comprising a conductive structure over the dielectric layer and a
conductive via extending downwards from the conductive structure
and through the dielectric layer, wherein the conductive via
comprises a bottom portion, a top portion, and a tapered portion
between the bottom and top portions, wherein the tapered portion
has a width variation greater than that of the bottom and top
portions.
2. The semiconductor structure of claim 1, wherein the tapered
portion tapers from the top portion to the bottom portion.
3. The semiconductor structure of claim 1, wherein the bottom
portion is in contact with the conductive line.
4. The semiconductor structure of claim 1, further comprising: a
protective layer over the RDL.
5. The semiconductor structure of claim 1, wherein a bottom surface
of the conductive via is below a top surface of the conductive
line.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a Divisional Application of the U.S.
application Ser. No. 16/439,690, filed on Jun. 12, 2019, the
entirety of which is incorporated by reference herein in their
entireties.
BACKGROUND
Technical Field
[0002] The present disclosure relates to a semiconductor structure.
More particularly, the present disclosure relates to a
semiconductor structure including a redistribution layer (RDL).
Description of Related Art
[0003] With the rapid growth of electronic industry, the
development of integrated circuits (ICs) has achieved high
performance and miniaturization. Technological advances in IC
materials and design have produced generations of ICs where each
generation has smaller and more complex circuits than the previous
generation. As a result, via holes for a redistribution layer (RDL)
of an IC are scaled down as well.
SUMMARY
[0004] According to some embodiments of the present disclosure, a
semiconductor structure includes a semiconductor device, a
conductive line, a dielectric layer and a redistribution layer
(RDL). The conductive line is present over the semiconductor
device. The dielectric layer is present over the conductive line.
The RDL includes a conductive structure over the dielectric layer
and a conductive via extending downwards from the conductive
structure and through the dielectric layer. The conductive via
comprises a bottom portion, a top portion, and a tapered portion
between the bottom and top portions, wherein the tapered portion
has a width variation greater than that of the bottom and top
portions.
[0005] According to some embodiments of the present disclosure, the
tapered portion tapers from the top portion to the bottom
portion.
[0006] According to some embodiments of the present disclosure, the
bottom portion is in contact with the conductive line.
[0007] According to some embodiments of the present disclosure, the
semiconductor structure further includes a protective layer. The
protective layer is present over the RDL.
[0008] According to some embodiments of the present disclosure, the
bottom surface of the conductive via is below the top surface of
the conductive line.
[0009] In summary, the disclosure provides a semiconductor
structure and fabrication method. The via hole includes the bottom
portion, the tapered portion, and the top portion. Since the
tapered portion and the top portion are wider than the bottom
portion, the tapered portion and the top portion can provide more
space for metal deposition, which in turn can mitigate any adverse
impact resulting from the overhang of following metal deposition.
Moreover, the bottom portion is more narrow than the tapered
portion and the top portion, in such a way, an improved via density
can be achieved.
[0010] It is to be understood that both the foregoing general
description and the following detailed description are by examples,
and are intended to provide further explanation of the disclosure
as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The disclosure can be more fully understood by reading the
following detailed description of the embodiment, with reference
made to the accompanying drawings as follows:
[0012] FIG. 1 is a schematic cross-section view showing a
semiconductor structure in accordance with some embodiments of the
present disclosure.
[0013] FIGS. 2-3 and 5-14 are schematic cross-sectional views of a
method of forming a semiconductor structure at various stages in
accordance with some embodiments of the present disclosure.
[0014] FIG. 4 is a schematic view of an embodiment of a photomask
which is used to pattern a photoresist layer.
DETAILED DESCRIPTION
[0015] Reference will now be made in detail to the present
embodiments of the disclosure, examples of which are illustrated in
the accompanying drawings. Wherever possible, the same reference
numbers are used in the drawings and the description to refer to
the same or like parts.
[0016] FIG. 1 is a schematic cross-section view showing a
semiconductor structure 10 in accordance with some embodiments of
the present disclosure. Referring to FIG. 1, a dielectric layer 300
is present over an interconnect structure 130 that is present over
a substrate 110. A redistribution layer 700a including a conductive
via 710 and a conductive structure 720a is present over the
substrate 110. The RDL 700a is in contact with the dielectric layer
300. A protective layer 900 is present over and covers the RDL
700a.
[0017] In some embodiments, the substrate 110 may be a silicon
substrate. Alternatively, the substrate 110 may include another
elementary semiconductor, such as germanium; a compound
semiconductor including silicon carbide, gallium arsenic, gallium
phosphide, indium phosphide, indium arsenide, and/or indium
antimonide; an alloy semiconductor including SiGe, GaAsP, AlInAs,
AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinations thereof. In
yet another alternative, the substrate 110 is a
semiconductor-on-insulator (SOI) such as having a buried layer.
[0018] In some embodiments, one or more active and/or passive
devices 120 are formed over the substrate 110. The one or more
active and/or passive devices 120 may include various N-type
metal-oxide semiconductor (NMOS) and/or P-type metal-oxide
semiconductor (PMOS) devices, such as transistors, capacitors,
resistors, diodes, photo-diodes, fuses, and the like.
[0019] The interconnect structure 130 is formed over the one or
more active and/or passive devices 120 and the substrate 110. The
interconnect structure 130 electrically interconnects the one or
more active and/or passive devices 120 to form functional
electrical circuits within the semiconductor structure 10. The
interconnect structure 130 may include one or more metallization
layers 140.sub.0 to 140.sub.n, wherein n+1 is the number of the one
or more metallization layers 140.sub.0 to 140.sub.n. In some
embodiments, the value of n may vary in response to design
specifications of the semiconductor structure 10. The metallization
layers 140.sub.1 to 140.sub.n may include dielectric layers
152.sub.1 to 152.sub.n, conductive plugs 160.sub.0, conductive
lines 170.sub.1 to 170.sub.n, and conductive vias 180.sub.1 to
180.sub.n. The dielectric layers 152.sub.1 to 152.sub.n are formed
over the corresponding dielectric layers 150.sub.1 to
150.sub.n.
[0020] In some embodiments, the metallization layer 140.sub.0 may
include conductive plugs 160.sub.0 through the dielectric layer
150.sub.0, and the metallization layers 140.sub.1 to 140.sub.n
comprise one or more conductive interconnects, such as conductive
lines 170.sub.1 to 170.sub.n respectively in dielectric layers
152.sub.1 to 152.sub.n and conductive vias 180.sub.1 to 180.sub.n
respectively in dielectric layers 150.sub.1 to 150.sub.n. The
conductive plugs 160.sub.0 electrically couple the one or more
active and/or passive devices 120 to the conductive lines 170.sub.1
to 170.sub.n and the conductive vias 180.sub.1 to 180.sub.n. In
some embodiments where a passive device 120 is a transistor, the
conductive plugs 160.sub.0 can be respectively land on a gate
electrode, and source/drain regions of the passive device
(transistor) 120 and thus respectively serve as a gate contact, and
source/drain contacts.
[0021] In some embodiments, the conductive plugs 160.sub.0, the
conductive lines 170.sub.1 to 170.sub.n and the conductive vias
180.sub.1 to 180.sub.n may be formed using any suitable method,
such as damascene, dual damascene, or the like. The conductive
plugs 160.sub.0, the conductive lines 170.sub.1 to 170.sub.n and
the conductive vias 180.sub.1 to 180.sub.n may comprise conductive
materials such as copper, aluminum, tungsten, combinations thereof,
or the like. In some embodiments, the conductive plugs 160.sub.0,
the conductive lines 170.sub.1 to 170.sub.n, and the conductive
vias 180.sub.1 to 180.sub.n may further comprise one or more
barrier/adhesion layers (not shown) to protect the respective
dielectric layers 150.sub.0 to 150.sub.n and 152.sub.0 to 152.sub.n
from metal diffusion and metallic poisoning. The one or more
barrier/adhesion layers may comprise titanium, titanium nitride,
tantalum, tantalum nitride, or the like, and may be formed using
physical vapor deposition (PVD), CVD, ALD, or the like.
[0022] FIGS. 2, 3 and 5-14 are schematic cross-sectional views of a
method of forming a semiconductor structure 10 at various stages in
accordance with some embodiments of the present disclosure. In
order to clearly illustrate the features in the present embodiment,
the substrate 110 and the interconnect structure 130 (as shown FIG.
1) are not shown in FIGS. 2, 3 and 5-14.
[0023] Referring to FIG. 2, a dielectric layer 300 is formed over
the conductive line 170.sub.n. The method of forming the dielectric
layer 300 may use, for example, PVD, CVD, ALD, or other suitable
technique. In some embodiments, the dielectric layer 300 may
include a single or multiple layers. The dielectric layer 300 may
include silicon oxide, silicon nitride, silicon oxynitride, or
other suitable materials. In some embodiments, a barrier layer (not
shown) is formed over the conductive line 170.sub.n before the
dielectric layer 300 is formed. The barrier layer may be beneficial
to the adhesion between the conductive line 170.sub.n and the
dielectric layer 300.
[0024] Referring to FIG. 3, a photoresist layer 400 is formed over
the dielectric layer 300. In some embodiments, the method of
forming the photoresist layer 400 may include forming a plasma
enhanced tetraethoxysilane (PETEOS) film over the dielectric layer
300. In some embodiments, the photoresist layer 400 may include an
organic material, such as a spin-on carbon (SOC) material, or the
like.
[0025] Referring to FIG. 4 and FIG. 5, FIG. 4 is a schematic view
of a photomask 410 which is used to pattern a photoresist layer 400
in FIG. 3. As shown in FIG. 4, the photomask 410 includes a light
transmissive portion 412, a light semi-transmissive portion 414,
and a light shielding portion 416. The density of light shielding
area of the light shielding portion 416 is larger than that of the
light semi-transmissive portion 414. The light semi-transmissive
portion 414 is present between the light transmissive portion 412
and the light shielding portion 416. In some embodiments, the
method of forming the photomask 410 with the light transmissive
portion 412, the light semi-transmissive portion 414, and the light
shielding portion 416 may use chrome on glass (COG), phase shift
mask, or other suitable methods.
[0026] As shown in FIG. 5, the photomask 410 (as shown FIG. 4) is
used to pattern the photoresist layer 400 (as shown FIG. 3) and
thus a mask feature 420 is formed. In other words, the photoresist
layer 400 (as shown FIG. 3) is patterned by using suitable
photolithography techniques to form a mask feature 420. The mask
feature 420 has an outer portion 422 and an inner portion 424. The
inner portion 424 is wider than the outer portion 422. The inner
portion 424 is in contact with the dielectric layer 300.
[0027] In the present embodiment, an opening 500 is defined by the
mask feature 420, and the opening 500 exposes the dielectric layer
300. The opening has a bottom portion 502 and a top portion 504,
and the top portion 504 is communicated to the bottom portion 502.
In greater detail, the bottom portion 502 has a width W1, while the
top portion 504 has a width W2. The width W2 is wider than the
width W1. Since the light transmissive portion 412,
semi-transmissive portion 414, and the shielding portion 416 of the
photomask 410 have different light transmission depths, the mask
feature 420 in FIG. 5 is caused to have the opening 500, and the
opening 500 has the bottom portion 502 with the width W1 and the
top portion 504 with the width W2.
[0028] Referring to FIG. 6, the dielectric layer 300 is etched
using the mask feature 420 as an etch mask. This etching process
results in a via hole 600 in the dielectric layer 300, and the via
hole 600 has substantially width W1 as the width W1 of the bottom
portion 502 of the opening 500 in the mask feature 420, because the
etching process is performed using the mask feature 420 as an etch
mask.
[0029] As shown in FIG. 6, a portion of the dielectric layer 300
remains below the via hole 600. The via hole 600 is present below
the opening 500. In other words, the portion of the dielectric
layer 300 remains between the via hole 600 and the underlying
conductive line 170.sub.n.
[0030] In some embodiments, the method of etching the dielectric
layer 300 may use dry etching. The dry etchant, e.g., H.sub.2 and
N.sub.2, may be selected for dry etching process to etch the
dielectric layer 300.
[0031] Referring to FIG. 7, the dielectric layer 300 is etched
using the mask feature 420 as an etch mask such that the via hole
600 is deepened and expanded. In greater details, the inner portion
424 of the mask feature 420 is consumed during the etching process,
and thickness of the outer portion 422 of the mask feature 420 is
reduced, such that the outer portion 422 of the mask feature 420 is
aligned with the inner portion 424 of the mask feature 420. In
other words, a portion of the dielectric layer 300 below the inner
portion 424 is etched after the inner portion 424 of the mask
feature 420 is consumed, thereby causing the via hole 600 having a
tapered profile. Stated differently, since the mask feature 420 (as
shown FIG. 6) has a stepped profile, e.g., the inner portion 424
and the outer portion 422, the via hole 600 has a tapered profile.
In some embodiments, the width of the top portion 504 of the
opening 500 is equal to that of the bottom portion 502 of the
opening 500. Since the mask feature 420 has an laterally expanded
bottom portion 502 of the opening 500, the etching process results
in laterally expanding the top portion 600t of the via hole 600 in
an interface of the dielectric layer 300 and the mask feature 420.
In greater detail, the top portion 600t of the via hole 600 is
expanded and has a width W2. For example, the width W2 of the top
portion 600t of the via hole 600 is equal to the width W2 of the
top portion 504 of the opening 500 in FIG. 5.
[0032] In some embodiments, etching the dielectric layer 300 to
expand the via hole 600 in FIG. 7 is in-situ performed with the
previous etching process in FIG. 6. Stated differently, the etching
process of expanding the via hole 600 and the etching process in
FIG. 6 can be performed without vacuum break. For example, the
etching process of expanding the via hole 600 and the etching
process in FIG. 6 can be performed in the same etching tool and
have substantially the same etching parameters.
[0033] Referring to FIG. 8, the dielectric layer 300 is etched
using the mask feature 420 as the etch mask. In greater detail, the
etching process deepens the via hole 600 until reaching the
conductive line 170.sub.n. In other words, the conductive line
170.sub.n is exposed. In some embodiments, etching the dielectric
layer 300 to deepen the via hole 600 in FIG. 8 is in-situ performed
with the previous etching process in FIG. 7. Stated differently,
the etching process of deepening the via hole 600 and the etching
process of expanding the via hole 600 (as shown in FIG. 7) can be
performed without vacuum break. For example, the etching process of
deepening the via hole 600 and the etching process of expanding the
via hole 600 can be performed in the same etching tool and have
substantially the same etching parameters.
[0034] Referring to FIG. 9, the dielectric layer 300 is etched
using the mask feature 420 as the etch mask. The etching process
deepens the via hole 600 such that a recess R is formed within the
conductive line 170.sub.n. In greater detail, the via hole 600 has
a bottom portion 602, a tapered portion 604 over the bottom portion
602, and a top portion 606 over the tapered portion 604. The
tapered portion 604 tapers from the top portion 606 to the bottom
portion 602. A width variation of the bottom portion 602 is less
than that of the tapered portion 604, and a width variation of the
top portion 606 is less than that of the tapered portion 604 as
well. The bottom portion 602 of the via hole 600 is in contact with
the conductive line 170.sub.n. In other words, the bottom portion
602 of the via hole 600 is in contact with the dielectric layer 300
and the conductive line 170.sub.n.
[0035] In some embodiments, the width of the bottom portion 602 is
substantially unchanged, and the width of the top portion 606 is
substantially unchanged as well. Since the tapered portion 604 and
the top portion 606 is wider than the bottom portion 602, the
tapered portion 604 and the top portion 606 can provide more space
for following metal deposition, which in turn can mitigate the
adverse impact resulting from overhang of following metal
deposition. Moreover, because the bottom portion 602 is narrower
than the tapered portion 604 and the top portion 606, an improved
via density can be achieved.
[0036] In some embodiments, deepening the via hole 600 within the
conductive line 170.sub.n is in-situ performed with the previous
etching process of deepening the via hole 600 in the dielectric
layer 300 (as shown in FIG. 8). In other words, the etching process
of deepening the via hole 600 within the conductive line 170.sub.n
and the etching process of deepening the via hole 600 in the
dielectric layer 300 can be performed without vacuum break. For
example, the etching process of deepening the via hole 600 within
the conductive line 170.sub.n and the etching process of deepening
the via hole 600 in the dielectric layer 300 can be performed in
the same etching tool and have substantially the same etching
parameters.
[0037] Referring to FIG. 10, the mask feature 420 is removed. In
some embodiments, removing the mask feature 420 may be performed by
using a photoresist strip process, such as an ashing process.
[0038] Referring to FIG. 11, a conductive material is filled in the
via hole 600. In other words, the conductive material is also
filled into the recess R (as shown FIG. 10). As shown in FIG. 11, a
conductive layer 700 is formed over the dielectric layer 300. In
the greater detail, the conductive layer 700 includes a conductive
via 710 and a conductive structure 720. The conductive layer 700
covers the dielectric layer 300 and is filled into the via hole 600
to form the conductive via 710 in the via hole 600. In some
embodiments, the conductive layer 700 includes a metal or a metal
alloy such as aluminum (Al), copper (Cu), other suitable conductive
material, or combinations thereof. The conductive layer 700 may be
formed by a PVD method such as sputtering method, or other suitable
methods.
[0039] In the present embodiment, the conductive via 710 extends
downwards from the conductive structure 720 and through the
dielectric layer 300. Because the conductive via 710 fills the via
hole 600, the conductive via 710 inherits the profile of the via
hole 600. In greater detail, the conductive via 710 includes a
bottom portion 712, a tapered portion 714, and a top portion 716.
The tapered portion 714 tapers from the top portion 716 to the
bottom portion 712. A width variation of the bottom portion 712 is
less than that of the tapered portion 714, and a width variation of
the top portion 716 is less than that of the tapered portion 714 as
well. For example, the width of the bottom portion 712 is
substantially unchanged, and the width of the top portion 716 is
substantially unchanged as well. In the present embodiment, the
bottom surface of the conductive via 710 is below the top surface
of the conductive line 170.sub.n.
[0040] Referring to FIG. 12, a patterned mask feature 800 is formed
over the conductive layer 700. The patterned mask feature 800
covers a portion of the conductive structure 720, while exposes the
other portion of the conductive structure 720. In the present
embodiment, the patterned mask feature 800 is a photoresist layer.
The method of forming the patterned mask feature 800 may include
first forming a photoresist layer and then patterning the
photoresist layer with a photolithography process.
[0041] Afterwards, the conductive layer 700 is patterned using the
patterned mask feature 800 as an etch mask. The resulting structure
is shown in FIG. 13. After patterning the conductive layer 700
using suitable etching techniques, the patterned mask feature 800
is removed by, for example, an ashing process. As shown in FIG. 13,
the redistribution layer (RDL) 700a includes a conductive structure
720a and the conductive via 710. The conductive structure 720a
covers the conductive via 710 and a portion of the dielectric layer
300, while exposes the other portion of the dielectric layer
300.
[0042] Referring to FIG. 14, a protective layer 900 is formed on
the substrate 110 to cover the RDL 700a and the dielectric layer
300. In some embodiments, the protective layer 900 is a single,
double, or multi-layer structure. The protective layer 900 may
include silicon oxide, silicon, silicon oxynitride, silicon
nitride, an organic material, a polymer or combinations thereof.
The organic material is, for example, benzocyclobutene (BCB), and
the polymer is, for example, polyimide (PI). The protective layer
900 may be formed by a CVD method, a coating method, or other
suitable method. In the present embodiment, the protective layer
900 includes a silicon oxide layer 910, a silicon nitride layer
920, and a polyimide layer 930.
[0043] In summary, the conductive via includes the bottom portion,
the tapered portion, and the top portion. Since the tapered portion
and the top portion are wider than the bottom portion, the tapered
portion and the top portion are beneficial to mitigating the
adverse impact, such as overhang of metal deposition. Moreover,
since the bottom portion is more narrow than the tapered portion
and the top portion, an improved via density can be achieved.
[0044] Although the present disclosure has been described in
considerable detail with reference to certain embodiments thereof,
other embodiments are possible. Therefore, the spirit and scope of
the appended claims should not be limited to the description of the
embodiments contained herein.
[0045] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
present disclosure without departing from the scope or spirit of
the disclosure. In view of the foregoing, it is intended that the
present disclosure cover modifications and variations of this
disclosure provided they fall within the scope of the following
claims.
* * * * *