U.S. patent application number 10/617679 was filed with the patent office on 2004-12-23 for method of polishing semiconductor copper interconnect integrated with extremely low dielectric constant material.
This patent application is currently assigned to CHUNG SHAN INSTITUTE OF SCIENCE & TECHNOLOGY. Invention is credited to Chu, Chih-Wei, Chung, Hsing-Liao, Fann, Yang-Jiann, Hsu, Chaug-Liang, Jeng, Yeau-Ren, Lai, Jer-Shyong, Pan, Wen-Chueh, Tsai, Meng-Shiun, Tsay, Ming-Tseh, Wang, Yih-Hsing.
Application Number | 20040259481 10/617679 |
Document ID | / |
Family ID | 33516546 |
Filed Date | 2004-12-23 |
United States Patent
Application |
20040259481 |
Kind Code |
A1 |
Pan, Wen-Chueh ; et
al. |
December 23, 2004 |
Method of polishing semiconductor copper interconnect integrated
with extremely low dielectric constant material
Abstract
A method of polishing metal and barrier layer interconnect
integrated with an extremely low dielectric constant material
includes steps of (A) preparing a wafer composed of a copper layer
and the extremely low dielectric constant material, (B) treating
the copper layer chemically to produce a hard and brittle surface
residual formed on the surface of the copper layer, (C) keeping
polishing the surface residual by ultrasonic waves, (D) polishing a
barrier layer of wafer by the ultrasonic waves, thereby polishing
the wafer successfully.
Inventors: |
Pan, Wen-Chueh; (Taipei,
TW) ; Lai, Jer-Shyong; (Taipei, TW) ; Wang,
Yih-Hsing; (Taipei, TW) ; Fann, Yang-Jiann;
(Taoyuan, TW) ; Chu, Chih-Wei; (Kaohsiung City,
TW) ; Chung, Hsing-Liao; (Taipei City, TW) ;
Hsu, Chaug-Liang; (Taipei, TW) ; Tsay, Ming-Tseh;
(Chinmen, TW) ; Jeng, Yeau-Ren; (Tainan City,
TW) ; Tsai, Meng-Shiun; (Tainan County, TW) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE
FOURTH FLOOR
ALEXANDRIA
VA
22314
|
Assignee: |
CHUNG SHAN INSTITUTE OF SCIENCE
& TECHNOLOGY
TAOYUAN
TW
|
Family ID: |
33516546 |
Appl. No.: |
10/617679 |
Filed: |
July 14, 2003 |
Current U.S.
Class: |
451/41 ;
257/E21.304 |
Current CPC
Class: |
B24B 1/04 20130101; H01L
21/3212 20130101; B24B 37/042 20130101 |
Class at
Publication: |
451/041 |
International
Class: |
B24B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 17, 2003 |
TW |
92116479 |
Claims
What is claimed is:
1. A method of polishing metal and barrier layer interconnect
integrated with an extremely low dielectric constant material, said
method comprising the steps of: (a) preparing a wafer composed of a
copper layer and the extremely low dielectric constant material,
said copper layer being positioned over the low dielectric constant
material, a barrier layer being positioned between said copper
layer and said low dielectric constant material; (b) treating said
copper layer chemically to produce a hard and brittle surface
residue layer on the surface of said copper layer; (c) applying
ultrasonic abrasion to said surface residue layer to cause the
brittle fracturing of said surface residue layer, thereby rendering
effective polishing of said wafer; (d) applying the ultrasonic
abrasion to said barrier layer to render effective polishing of
said wafer.
2. The method as defined in claim 1, wherein said surface residue
layer in the step (b) is a cuprous compound.
3. The method as defined in claim 2, wherein said cuprous compound
is cuprous oxide.
4. The method as defined in claim 1, wherein said ultrasonic
abrasion is worked by that apply ultrasonic waves to a pad to
enable said pad to move and to drive abrasive of abrasive slurry to
abrade and polish said wafer.
5. The method as defined in claim 4, wherein said ultrasonic waves
applied to said pad are transversal traveling or standing
waves.
6. The method as defined in claim 1, wherein said ultrasonic
abrasion is worked by that apply cavitation generated by scanning
of the ultrasonic waves clustered by array-type structure to
proceed to abrasion and polish.
7. The method as defined in claim 1, wherein said ultrasonic
abrasion is worked by that apply the ultrasonic waves to a pad to
enable said pad to drive abrasive slurry with abrasive to flow on
the surface of said wafer, thereby generating and applying shearing
force to abrade and polish the surface of said wafer.
8. The method as defined in claim 7, wherein said ultrasonic waves
enable said abrasive slurry to generate hydrodynamic pressure via
said pad for reducing the increasing relative velocity and the
threshold pressure of the polishing process, and work as assistance
to enhance the chemical treatment to render uniform effect.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to technology of
polishing wafer, and more particularly, to a method of polishing
copper & Tantalum Nitride (Ta/TaN) interconnect integrated with
an extremely low dielectric constant material, which works on the
surface of wafer by means of ultrasonic waves.
[0003] 2. Description of the Related Art
[0004] A conventional chemical mechanical polish method (CMP) can
work on wafer with greater force. As to the wafer integrated with
low dielectric constant material, which is low in intensity,
durability, hardness, and stability, it needs extremely low down
and shear force to polish the wafer; otherwise, lead frame or
dielectric layer or interface of the film on wafer will be spoiled.
If the aforementioned extremely little force is made by decreasing
a down force by a precise control technique, it will be difficult
to manufacture such a particular machine, which performs the
precise control technique, and will cost a lot of money. In
addition, a barrier layer positioned on the wafer is made of the
chemically inert Ta/TaN, such that polishing the wafer with
extremely little force is hardly possible. Hence, the conventional
method of polishing wafer with great force will hardly meet the
future requirement of polishing copper & Ta/TaN, which are
integrated with extreme-low dielectric constant material.
[0005] Furthermore, though another conventional method of polishing
wafer without forces by chemical or electrochemical treatment,
relatively to the mechanical pressure used by a conventional method
of polishing wafer, applies no force on the surface of wafer, it
merely successfully works on a copper layer but ineffectively on
the barrier layer.
SUMMARY OF THE INVENTION
[0006] The primary objective of the present invention is to provide
a method of polishing metal and barrier layer interconnect
integrated with an extremely low dielectric constant material,
which improves the drawbacks of the mechanical great force and the
electrochemical non-force of the conventional polishing methods and
is adapted to work on semiconductor copper interconnect integrated
with the extremely low dielectric constant material.
[0007] The foregoing objective of the present invention is attained
by the method of polishing metal and barrier layer interconnect
integrated with an extremely low dielectric constant material,
which includes steps of (A) preparing a wafer composed of a copper
layer and the extremely low dielectric constant material, (B)
treating the copper layer chemically to produce a hard and brittle
surface residual formed on the surface of the copper layer, (C)
keeping polishing the surface residual by ultrasonic waves, and (D)
polishing a barrier layer of the wafer by the ultrasonic waves,
thereby polishing the wafer successful.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic view of wafer on which the present
invention constructed according to a first preferred embodiment is
working;
[0009] FIGS. 2A, 2B, and 2C show the variations of the surface of
the wafer during the polishing process constructed according to the
first preferred embodiment of the present invention;
[0010] FIG. 3 is a schematic view of the wafer on which the present
invention constructed according to a second preferred embodiment is
working;
[0011] FIG. 4 is a perspective view of the wafer on which the
present invention constructed according to a second preferred
embodiment is working by means of ultrasonic waves; and
[0012] FIG. 5 is a schematic view of the wafer on which the present
invention constructed according to a third preferred embodiment is
working.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Referring to FIGS. 1 and 2, a method of polishing metal and
barrier layer interconnect integrated with an extremely low
dielectric constant material, which is constructed according to a
first preferred embodiment of the present invention, includes steps
as follows.
[0014] A. Prepare a wafer 10 composed of a copper layer 11 and the
extremely low dielectric constant material 21; wherein, the copper
layer 11 is positioned over the low dielectric constant material
21, and a barrier layer 31 embodied as Tantalun Nitride which is a
chemically inert, hard, and brittle ceramic material is positioned
between the copper layer 11 and the low dielectric constant
material 21.
[0015] B. Treat the copper layer 11 chemically to produce a hard
and brittle surface residue layer 12 embodied as a cuprous compound
layer on the surface of the copper layer 11. For example, the
cuprous compound layer can be cuprous oxide, which is preferably
hard and brittle to be evenly polished by ultrasonic waves.
[0016] C. Apply the ultrasonic waves to a pad 51 to enable the pad
51 to move and to further enable abrasive of abrasive slurry to
polish the surface residue layer 12, as shown in FIG. 2A, thereby
removing the surface residue layer 12 uniformly, as shown in FIG.
2B.
[0017] D. Apply the ultrasonic waves to the tool with the pad 51 to
enable the pad 51 to move and to further enable the abrasive of the
abrasive slurry to polish the barrier layer 31, thereby causing the
polished barrier layer 31 successfully, as shown in FIG. 2C.
[0018] In the present embodiment, the ultrasonic waves 90 applied
to the pad 51 which contacts the surface of the wafer 10 can be
transversal or longitudinal waves; the transversal waves enable
transversal traveling waves or standing waves parallel to the
surface of the wafer 10 to drive the pad 51 to proceed elliptical
movement, and meanwhile, a rough surface of the pad 51 drives the
abrasive of the abrasive slurry to polish the wafer 10; the
longitudinal waves enable longitudinal traveling waves or standing
waves perpendicular to or crossed with the surface of the wafer 10
at any angle to drive the abrasive of the abrasive slurry to
reciprocate and impact on the wafer 10, and meanwhile, the surface
residue layer 12 of the wafer 10 is of brittle fracturing during
polishing process; In addition, the transversal waves can enable
longitudinal traveling waves or standing waves parallel to the
surface of the wafer 10 to drive the pad 51 to reciprocate, and
meanwhile, the rough surface of the pad 51 drives the abrasive of
the abrasive slurry to polish the wafer 10.
[0019] Referring to FIGS. 3 and 4, the method of polishing
semiconductor copper interconnect integrated with the extremely low
dielectric constant material, which is constructed according to a
second preferred embodiment of the present invention, is different
from the aforementioned embodiment only in steps C and D as
follows.
[0020] C. Apply extremely great cavitation damage of cavitation
generated by means of scanning of the ultrasonic waves 90 clustered
by array-type structure to the very surface and very micro area of
the surface residue layer 12' to cause the brittle fracturing of
the surface residue layer 12', thereby polishing the wafer 10
successfully.
[0021] D. Apply the extremely great cavitation damage of the
cavitation generated by means of scanning of the ultrasonic waves
90 clustered by array-type structure to the very surface and very
micro area of the barrier layer 31' to cause the brittle fracturing
of the barrier layer 12', thereby polishing the wafer 10
successfully.
[0022] In this embodiment, except the pad, only the cavitation
generated by the ultrasonic waves is applied to polish the surface
of the wafer.
[0023] Referring to FIG. 5, the method of polishing semiconductor
copper interconnect integrated with the extremely low dielectric
constant material, which is constructed according to a third
preferred embodiment of the present invention, is different from
the aforementioned embodiments only in steps C and D in which the
ultrasonic waves 90 are applied to a pad 51" to enable the pad 51"
to drive the abrasive slurry 52" to flow on the surface of the
wafer 10", thereby generating and applying shearing force to polish
the surface of the wafer 10". During the aforementioned process,
the pad 51" never touches the surface of the wafer 10". The
ultrasonic waves generate the hydrodynamic pressure for reducing
the threshold pressure of the polishing process by eliminating the
hydroplaning effect. Such kind of the ultrasonic polishing process
is also worked as assistance to enhance the chemical treatment to
render uniform effect.
[0024] In light of above three preferred embodiments of the present
invention, the polishing process of the copper layer can be done
not only by polishing the brittle and hard surface compound of the
copper layer by the ultrasonic waves, but also polishing the
surface residue layer of the soft material on the conventional
copper layer by extremely little force generated by various
applications of the ultrasonic waves, which causes uniform
polishing effect.
[0025] Please be noted that the brittle surface residue layer 12
generated by the chemical treatment is not only limited to a
cuprous compound layer but can be anything brittle generated by
other chemical treatment.
[0026] In conclusion, the present invention utilizes the ultrasonic
waves 90 to proceed to micro polishing not only on the surface of
the wafer 10 to avoid great mechanical force, but also effectively
on the copper layer 11 and the barrier layer 31. In addition, the
pulse force is generated during polishing process, such that the
damage owing to the extremely low dielectric material could be
avoided. Accordingly, the present invention effectively improves
the drawbacks of the conventional CMP and the conventional chemical
polish.
* * * * *