U.S. patent application number 13/791431 was filed with the patent office on 2014-09-11 for method of etching an etch layer.
This patent application is currently assigned to Lam Research Corporation. The applicant listed for this patent is LAM RESEARCH CORPORATION. Invention is credited to Yezdi N. DORDI.
Application Number | 20140256142 13/791431 |
Document ID | / |
Family ID | 51399937 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140256142 |
Kind Code |
A1 |
DORDI; Yezdi N. |
September 11, 2014 |
METHOD OF ETCHING AN ETCH LAYER
Abstract
A method for etching an etch layer is provided. A glue layer
having metallizable terminations is formed over the etch layer. The
glue layer is exposed to a patterned light, wherein the
metallizable terminations of the glue layer illuminated by the
patterned light become unmetallizable. A metal deposition layer is
formed on the glue layer, wherein the metal deposition layer only
deposits on areas of the glue layer with metallizable terminations
of the glue layer. The etch layer is etched through portions of the
glue layer without the metal deposition layer.
Inventors: |
DORDI; Yezdi N.; (Palo Alto,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LAM RESEARCH CORPORATION |
Fremont |
CA |
US |
|
|
Assignee: |
Lam Research Corporation
Fremont
CA
|
Family ID: |
51399937 |
Appl. No.: |
13/791431 |
Filed: |
March 8, 2013 |
Current U.S.
Class: |
438/703 |
Current CPC
Class: |
H01L 21/31144 20130101;
H01L 21/3105 20130101; H01L 21/0234 20130101; H01L 21/02115
20130101; H01L 21/02274 20130101; H01L 21/02359 20130101 |
Class at
Publication: |
438/703 |
International
Class: |
H01L 21/308 20060101
H01L021/308 |
Claims
1. A method for etching an etch layer, comprising: forming a glue
layer having metallizable terminations over the etch layer;
exposing the glue layer to a patterned light, wherein the
metallizable terminations of the glue layer illuminated by the
patterned light become unmetallizable; forming a metal deposition
layer on the glue layer, wherein the metal deposition layer only
deposits on areas of the glue layer with metallizable terminations
of the glue layer; and etching the etch layer through portions of
the glue layer without the metal deposition layer.
2. The method of claim 1, wherein the metal deposition layer
attaches to the metallizable terminations.
3. The method, as recited in claim 2, wherein the patterned light
is ultraviolet light.
4. The method, as recited in claim 2, wherein the patterned light
is extreme ultraviolet light.
5. The method of claim 4, wherein terminations become
unmetallizable when the patterned light breaks covalent bonds of
the metallizable terminations.
6. The method of claim 5, wherein the glue layer is
carbon-based.
7. The method of claim 5, wherein the glue layer is amorphous
carbon.
8. The method of claim 4, wherein the glue layer is
silicon-based.
9. The method of claim 5, further comprising removing the metal
deposition layer and the glue layer.
10. The method of claim 5, wherein the metallizable terminations
comprise at least one of an amine or an oxygen based metallizable
termination.
11. The method, as recited in claim 1, wherein the patterned light
is ultraviolet light.
12. The method, as recited in claim 1, wherein the patterned light
is extreme ultraviolet light.
13. The method of claim 1, wherein terminations become
unmetallizable when the patterned light breaks covalent bonds of
the metallizable terminations.
14. The method of claim 1, wherein the glue layer is
carbon-based.
15. The method of claim 1, wherein the glue layer is amorphous
carbon.
16. The method of claim 1, wherein the glue layer is
silicon-based.
17. The method of claim 1, further comprising removing the metal
deposition layer and the glue layer.
18. The method of claim 1, wherein the metallizable terminations
comprise at least one of an amine or an oxygen based metallizable
termination.
19. A method for etching an etch layer, comprising: forming an
amorphous carbon glue layer having metallizable terminations over
the etch layer; exposing the amorphous carbon glue layer to a
patterned ultraviolet light, wherein the metallizable terminations
of the amorphous carbon glue layer illuminated by the patterned
ultraviolet light become unmetallizable; forming a metal deposition
layer on the amorphous carbon glue layer, wherein the metal
deposition layer only deposits on areas of the amorphous carbon
glue layer with metallizable terminations of the amorphous carbon
glue layer, wherein the metal deposition layer attaches to the
metallizable terminations; and etching the etch layer through
portions of the amorphous carbon glue layer without the metal
deposition layer.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a method of manufacturing
semiconductor devices. More specifically, the invention relates to
etching an etch layer during the manufacture of semiconductor
devices.
SUMMARY OF THE INVENTION
[0002] To achieve the foregoing and in accordance with the purpose
of the present invention, a method for etching an etch layer is
provided. A glue layer having metallizable terminations is formed
over the etch layer. The glue layer is exposed to a patterned
light, wherein the metallizable terminations of the glue layer
illuminated by the patterned light become unmetallizable. A metal
deposition layer is formed on the glue layer, wherein the metal
deposition layer only deposits on areas of the glue layer with
metallizable terminations of the glue layer. The etch layer is
etched through portions of the glue layer without the metal
deposition layer.
[0003] In another manifestation of the invention, a method for
etching an etch layer is provided. An amorphous carbon glue layer
having metallizable terminations is formed over the etch layer. The
amorphous carbon glue layer is exposed to a patterned ultraviolet
light, wherein the metallizable terminations of the amorphous
carbon glue layer illuminated by the patterned ultraviolet light
become unmetallizable. A metal deposition layer is formed on the
amorphous carbon glue layer, wherein the metal deposition layer
only deposits on areas of the amorphous carbon glue layer with
metallizable terminations of the amorphous carbon glue layer. The
etch layer is etched through portions of the amorphous carbon glue
layer without the metal deposition layer.
[0004] These and other features of the present invention will be
described in more details below in the detailed description of the
invention and in conjunction with the following figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The present invention is illustrated by way of example, and
not by way of limitation, in the figures of the accompanying
drawings and in which like reference numerals refer to similar
elements and in which:
[0006] FIG. 1 is a flow chart of an embodiment of the
invention.
[0007] FIGS. 2A-2F are schematic views of the formation of
structures using the inventive process.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0008] The present invention will now be described in detail with
reference to a few preferred embodiments thereof as illustrated in
the accompanying drawings. In the following description, numerous
specific details are set forth in order to provide a thorough
understanding of the present invention. It will be apparent,
however, to one skilled in the art, that the present invention may
be practiced without some or all of these specific details. In
other instances, well known process steps and/or structures have
not been described in detail in order to not unnecessarily obscure
the present invention.
[0009] In the formation of semiconductor devices, a photoresist
mask using EUV (extreme ultraviolet) light would produce higher
resolution patterns than photoresists using lower frequencies of
light. Current EUV light sources generate 10 watts of power to the
wafer. However, 250 watts is currently needed for a viable process
that utilizes commercial EUV photoresists. In particular, the
commercial EUV photoresists are too thick for the 10 watt EUV light
sources to fully penetrate.
[0010] FIG. 1 is a high level flow chart of an embodiment of the
invention. In this embodiment, a glue layer having metallizable
termination is formed (step 104). The glue layer is formed over an
etch layer. The glue layer is exposed to a patterned light (step
108). In particular, the metallizable terminations of the glue
layer that are illuminated by the patterned light become
unmetallizable. A metal deposition layer is formed on the glue
layer (step 112). The metal deposition layer only deposits on areas
of the glue layer with metallizable terminations. The etch layer is
etched (step 116). In particular, the etch layer is etched through
unmetallizable portions of the glue layer without the metal
deposition layer. The glue layer and metal layer are removed (step
120).
EXAMPLE
[0011] In an embodiment of the invention, an exemplary method for
etching a etch layer is provided. Initially, a glue layer having
metallizable terminations is formed over the etch layer (step 104).
The etch layer may be a layer above a silicon wafer, or it may be
the silicon wafer itself. The etch layer may be a single layer or a
stack of different layers, such as a composite stack consisting of
a dielectric hardmask and an oxide layer. The etch layer may be one
or more of a dielectric layer and/or conductive layer. Accordingly,
FIG. 2A illustrates a glue layer 202, in accordance with
embodiments of the present invention. In particular, FIG. 2A
includes an etch layer 200, glue layer 202, and metallizable
terminations 204. In this embodiment, a two-step process is used to
form the glue layer 202. The glue layer 202 is formed by covering
the etch layer 200 with an amorphous carbon layer and then passing
the amorphous carbon layer through an ammonia plasma so as to form
amine terminations. The amine terminations of the glue layer 202
are metallizable terminations 204. The metallizable terminations
204 allow a metal layer to attach to the glue layer 202. In this
embodiment, the etch layer 200 is over a substrate 205. One or more
layers may be between the etch layer 200 and the substrate 205. In
other embodiments, the etch layer may be the substrate 205 without
an underlying layer. In this example, the etch layer is an oxide
layer. An example of a two step process would use a TCP chamber
built by Lam Research.RTM. of Fremont, Calif. The glue layer would
be provided by providing a glue layer gas of 350 sccm H.sub.2, 50
sccm CH.sub.4, and 200 sccm He. 500 watts of TCP power are provided
to form the glue layer gas into a plasma. The bias is provided at 0
volts. A pressure is maintained at 20 mTorr. The plasma is
maintained for 15 seconds. The metallizable terminations are formed
by providing a metallizable termination gas of 350 sccm H.sub.2 and
50 sccm NH.sub.3 from a gas source into the TCP chamber. 500 watts
of TCP power are provided to form the metallizable termination gas
into a plasma. The bias is provided at 0 volts. A pressure is
maintained at 20 mTorr. The plasma is maintained for 10
seconds.
[0012] As illustrated in FIG. 2B, the glue layer 202 is exposed to
a patterned light (step 108). In this example, the patterned light
comprises exposure of EUV. This is achieved by placing reticle 206
over the glue layer 202. Accordingly, portions 208 of the
metallizable terminations 204 of the glue layer 202 are exposed to
EUV. The portions 208 of the metallizable terminations 204 that are
exposed to the EUV become unmetallizable. The EUV source may
provide an intensity of about 10 Watts to the wafer.
[0013] In this example, covalent bonds within metallizable
terminations are broken by exposure to EUV. The metallizable
terminations 204 become unmetallizable when their covalent bonds
are broken. Accordingly, FIG. 2C illustrates portions 208 as being
unmetallizable terminations 210. For purposes of illustration, the
denaturing of the metallizable terminations 204 is shown as the
transformation of the portions 208 to unmetallizable terminations
210.
[0014] In FIG. 2D, a metal deposition layer 212 is formed on the
glue layer 202 (step 112). Portions of the glue layer 202 that are
metallizable are covered with the metal deposition layer 212. The
metal deposition layer 212 is attached to metallizable terminations
204 of the glue layer 202. Portions that have been transformed to
unmetallizable terminations 210 do not have a metal deposition
layer. In particular, the metals that may be deposited on a glue
layer, such as glue layer 202, are associated with particular
metallizable terminations. Some metals, such as cobalt and copper,
may attach to amine-based metallizable terminations. In this
embodiment, a cobalt metal deposition layer 212 is attached to glue
layer 202 by attaching to the amine metallizable terminations using
electroless deposition. Further, the unmetallizable terminations
210 are not covered with a metal deposition layer 212. In an
example of an electroless deposition, the glue layer is subjected
to a palladium (Pd) treatment of a solution of 0.1 g/L of
PdCl.sub.2 and 3.5 ml/L of 36% HCl for 1 minute. The glue layer is
then rinsed with deionized water. The glue layer is then exposed to
a solution of 0.05 M CoSO.sub.4, 0.2 M dimethylamine borane (DMAB),
and 0.01 M diethylenetriamine for 1 to 3 minutes. The glue layer is
then rinsed and dried.
[0015] The metal deposition layer 212 is used as a patterned mask
to etch the etch layer 200 (step 116). The portions of the mask
with the unmetallizable terminations 210 are etched through while
the portions of the mask with metallizable terminations 204 and
having a metal deposition layer 212 are protected. In this example,
a single etch step is used to etch both the portions of the mask
without a metal deposition layer 212 and the etch layer 200. In
other embodiments, different etch processes may be used to etch the
glue layer 202 and the etch layer 200. FIG. 2E illustrates the
etched portions 214 of etch layer 200. In this example, the
features have a CD width of less than 12 nm and a depth of at least
60 nm.
[0016] The glue layer 202 and metal deposition layer 212 are
removed (step 120). In this embodiment a wet etch may be use to
remove the glue layer 202 and the metal deposition layer 212 and to
provide a post etch wet clean. FIG. 2F illustrates the etch layer
200 after the glue layer and the metal deposition layer have been
removed.
[0017] This embodiment allows for the formation of etch features
using a mask that is exposed to EUV. Since EUV has a higher
frequency than deep ultraviolet (DUV), the resulting features have
a lower CD than features formed using DUV. The invention allows for
low intensity EUV, with an intensity of 10 Watts, to be used for
forming a patterned mask in an etching process. This embodiment
also allows for the formation of a metal patterned mask, which may
be used to increase etch selectivity.
[0018] In other embodiments, the glue layer may be formed using a
single step process, such as by using self-assembled monolayer
(SAM) process or a Post Etch Treatment (PET) process, which form
the glue layer and metallizable terminations in a single step. In a
preferred embodiment of the present invention a two step formation
of the glue layer, is used to reduce defects.
[0019] In another embodiment, the glue layer is formed using an
atomic deposition layer (ALD) process. During ALD, the glue layer
may be formed in a level-by-level process with desired materials
deposited during multiple steps.
[0020] In embodiments, glue layer may be other carbon-based
materials or may be silicon-based. A silicon-based glue layer may
be formed using a polysilicon or a silicon nitride. In some
embodiments, one or more layers may be disposed between the glue
layer and etch layer.
[0021] Various metals may be used as metal deposition layers in
accordance with embodiments of the present invention. In
particular, palladium, nickel, cobalt, and copper may be used in
association with amine metallizable terminations. In contrast,
aluminum, nickel, and titanium would more ideally attach to
oxygen-based metallizable terminations, such as --COOH. In other
embodiments, metallizable terminations may include amine, thiol,
and carboxylic acid. Other embodiments may use other deposited
metals, such as tantalum, which attaches to oxygen-based
metallizable terminations. Other metals that may be used as metal
deposition layers include ruthenium, palladium, iron, and
tungsten.
[0022] An above example provides electroless deposition in an
aqueous solution. In other embodiments, electroless deposition may
be provided in a nonaqueous solution.
[0023] In other embodiments in place of electroless deposition,
nanoparticles of metal are provided to the metallizable
terminations. Such nanoparticles attach to the metallizable
terminations. Nanoparticles of metal are particles that are between
1 nm to 100 nm in diameter. When the nanoparticles in a suspension
contact a metallizable termination, they coalesce to reach a lower
energy level combining with each other and attaching to the
metallizable termination. In another embodiment, atomic layer
deposition is used to form the metal layer on the metallizable
terminations. Other methods may be used to form the metal layer on
the metallizable terminations. Such methods would attach metal to
the metallizable terminations, but not to the unmetallizable
terminations, forming a layer without defect and with a thickness,
preferably between 1 nm to 100 nm in diameter. A layer without
defects preferably would not have holes in the metal layer where
there are metallizable terminations and would not deposit metal
where there are unmetallizable terminations.
[0024] While this invention has been described in terms of several
preferred embodiments, there are alterations, permutations, and
various substitute equivalents, which fall within the scope of this
invention. It should also be noted that there are many alternative
ways of implementing the methods and apparatuses of the present
invention. It is therefore intended that the following appended
claims be interpreted as including all such alterations,
permutations, and various substitute equivalents as fall within the
true spirit and scope of the present invention.
* * * * *