U.S. patent application number 10/319256 was filed with the patent office on 2004-06-17 for abrasive with a modified surface and a method for making it.
Invention is credited to Buehler, Mark F..
Application Number | 20040111976 10/319256 |
Document ID | / |
Family ID | 32325993 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040111976 |
Kind Code |
A1 |
Buehler, Mark F. |
June 17, 2004 |
ABRASIVE WITH A MODIFIED SURFACE AND A METHOD FOR MAKING IT
Abstract
A composition is described that comprises an abrasive, and a
hydrocarbon containing component that is coupled to the abrasive.
Such a composition may be included in a slurry that is used to
polish a substrate, when forming a semiconductor device. Also
described is a method for modifying a surface of an abrasive that
comprises coupling a hydrocarbon containing component to the
surface of the abrasive.
Inventors: |
Buehler, Mark F.; (Portland,
OR) |
Correspondence
Address: |
INTEL CORPORATION
P.O. BOX 5326
SANTA CLARA
CA
95056-5326
US
|
Family ID: |
32325993 |
Appl. No.: |
10/319256 |
Filed: |
December 12, 2002 |
Current U.S.
Class: |
51/308 ; 106/3;
438/691; 438/692; 438/693 |
Current CPC
Class: |
C09K 3/1454 20130101;
C09K 3/1436 20130101; B24D 18/00 20130101 |
Class at
Publication: |
051/308 ;
106/003; 438/691; 438/692; 438/693 |
International
Class: |
B24B 001/00 |
Claims
What is claimed is:
1. A method of modifying a surface of an abrasive comprising:
coupling a hydrocarbon containing component to the surface of the
abrasive.
2. The method of claim 1 wherein the abrasive is an oxide
abrasive.
3. The method of claim 2 wherein the abrasive is a silica abrasive
or an alumina abrasive.
4. The method of claim 3 wherein the abrasive is a fumed silica or
a colloidal silica.
5. The method of claim 1 wherein the hydrocarbon containing
component comprises a hydrocarbon ligand and a coupling agent for
coupling the hydrocarbon ligand to the surface of the abrasive.
6. The method of claim 5 wherein the coupling agent comprises a
hydroxyl or alkoxy group.
7. The method of claim 6 wherein the hydrocarbon containing
component has the molecular formula (OX).sub.yMA.sub.bR, wherein X
is hydrogen or an alkyl group, y is between 1 and 3, M is a metal
element, A comprises a constituent bonded to the metal element, b
is between 0 and 2, and R is a hydrocarbon ligand.
8. The method of claim 7 wherein M is silicon.
9. The method of claim 6 wherein the hydrocarbon containing
component is coupled to the surface of the abrasive by reacting the
hydrocarbon containing component's hydroxyl or alkoxy group with a
hydroxyl group located on the abrasive's surface.
10. A method of forming a semiconductor device comprising:
polishing a substrate with a slurry that comprises a hydrocarbon
containing component that is coupled to the surface of an
abrasive.
11. The method of claim 10 wherein the substrate comprises a
metal.
12. The method of claim 10 wherein the substrate comprises a
dielectric layer.
13. The method of claim 10 wherein the hydrocarbon containing
component has the molecular formula (OX).sub.yMOA.sub.bR, wherein X
is hydrogen or an alkyl group, y is between 0 and 2, M is a metal
element, A comprises a constituent bonded to the metal element, b
is between 0 and 2, and R is a hydrocarbon ligand, and wherein the
abrasive is a silica abrasive or an alumina abrasive.
14. A composition comprising: an abrasive; and a hydrocarbon
containing component that is coupled to the abrasive.
15. The method of claim 14 wherein the abrasive is an oxide
abrasive.
16. The composition of claim 15 wherein the abrasive is a silica
abrasive or an alumina abrasive.
17. The composition of claim 16 wherein the abrasive is a fumed
silica or a colloidal silica.
18. The composition of claim 15 wherein the hydrocarbon containing
component comprises a hydrocarbon ligand that is coupled to the
oxide abrasive.
19. The composition of claim 18 wherein the hydrocarbon containing
component has the molecular formula (OX).sub.yMOA.sub.bR, wherein X
is hydrogen or an alkyl group, y is between 0 and 2, M is a metal
element, A comprises a constituent bonded to the metal element, b
is between 0 and 2, and R is a hydrocarbon ligand.
20. The composition of claim 19 wherein M is silicon.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to abrasives for use in
chemical mechanical polishing, in particular, the polishing of
metal or dielectric layers that may be formed when making
semiconductor devices.
BACKGROUND OF THE INVENTION
[0002] Semiconductor devices may include a shallow trench isolation
region and several metal layers that are separated by dielectric
layers. As that region and those layers are formed, it may be
necessary to remove from the device excess metal or dielectric
material. A chemical mechanical polishing process is commonly used
to perform that function. In such a process, a slurry may be
dispensed onto a polishing pad to facilitate removal of the excess
material.
[0003] Although a slurry's composition may differ depending upon
the type of material that is removed during the polishing
operation, it generally will include an abrasive. For the chemical
mechanical polishing of metal or dielectric material, two forms of
silica abrasive are commonly used--i.e., fumed silica and colloidal
silica. Fumed silica may, for example, be used when polishing the
dielectric material that forms the device's shallow trench
isolation region. Colloidal silica may be used when polishing
barrier layers, e.g., those comprising tantalum. In general, fumed
silica enables a high polish rate, but exhibits poor defect
performance, while using colloidal silica may limit defects, but
may also reduce the polishing rate.
[0004] In many applications, however, both a high polish rate and
good defect performance are desired. Accordingly, there is a need
for an abrasive that facilitates a high polish rate while providing
satisfactory defect performance. The composition of the present
invention provides such an abrasive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIGS. 1a-1b represent embodiments of the composition of the
present invention.
[0006] FIG. 2 illustrates a mechanism believed to cause a
hydrocarbon containing component to attach to the surface of an
abrasive.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0007] A composition is described that comprises an abrasive, and a
hydrocarbon containing component that is coupled to the abrasive.
The composition may be included in a slurry that is used to polish
a substrate. Also described is a method for modifying a surface of
an abrasive that comprises coupling a hydrocarbon containing
component to the surface of the abrasive.
[0008] In the following description, a number of details are set
forth to provide a thorough understanding of the present invention.
It will be apparent to those skilled in the art, however, that the
invention may be practiced in many ways other than those expressly
described here. The invention is thus not limited by the specific
details disclosed below.
[0009] In one embodiment of the composition of the present
invention, the abrasive is an oxide abrasive, e.g., a silica
abrasive or an alumina abrasive, and the hydrocarbon containing
component comprises a hydrocarbon ligand that is coupled to the
oxide abrasive. The hydrocarbon containing component may have the
molecular formula (OX).sub.yMOA.sub.bR, in which X is hydrogen or
an alkyl group, y is between 0 and 2, M is a metal element, A
comprises a constituent bonded to the metal element, b is between 0
and 2, and R is the hydrocarbon ligand. In a preferred embodiment,
M is silicon. The hydrocarbon ligand may comprise alkyl chains of
varying length to which one or more functional groups may be
attached. Functional groups, which may be coupled to such an alkyl
chain, may have oxidizing or reducing properties. Examples of such
functional groups include carboxylic acid, aldehydic, phosphoric,
sulfuric, nitrate or amino groups.
[0010] FIGS. 1a and 1b represent examples of compositions that
include such a hydrocarbon containing component. The figure 1a
composition represents an abrasive derived from a fumed silica or a
colloidal silica. Surface 100 of the silica component is coupled to
hydrocarbon containing component 101 via a chemical bond. In this
embodiment, silicon atom 102 is bonded to the hydrocarbon ligand R
and to a pair of hydroxyl groups. FIG. 1b represents a similar
composition in which the abrasive is derived from an alumina
abrasive instead of a silica abrasive. In this embodiment, surface
103 of the alumina component is coupled to hydrocarbon containing
component 104 via the bonds between oxygen atom 105 and silicon
atom 106 and between oxygen atom 105 and aluminum atom 107.
[0011] To make the composition of the present invention, the
surface of an abrasive is modified by coupling to it a hydrocarbon
containing component. The hydrocarbon containing component may
comprise a hydrocarbon ligand and a coupling agent for coupling the
hydrocarbon ligand to the surface of the abrasive. When the
coupling agent comprises a hydroxyl or alkoxy group, the
hydrocarbon containing component may have the molecular formula
(OX).sub.yMA.sub.bR, in which X is hydrogen or an alkyl group, y is
between 1 and 3, M is a metal element (e.g., silicon), A comprises
a constituent bonded to the metal element, b is between 0 and 2,
and R is a hydrocarbon ligand. Preferably, the hydrocarbon ligand
comprises an alkyl chain with no more than about 20 carbon
atoms.
[0012] Such a hydrocarbon containing component may be coupled to
the abrasive's surface by exposing the abrasive to a solution that
contains that component. The hydrocarbon containing component and
the abrasive should be allowed to react for a sufficient time to
enable that component to bond to the abrasive's surface. The
reaction rate, and the extent to which the hydrocarbon containing
component covers the abrasive's surface, may depend upon the
concentration of that component, and the solution's
temperature.
[0013] FIG. 2 illustrates a mechanism believed responsible for
causing a hydrocarbon containing component, with at least one
hydroxyl group, to attach to an abrasive's surface. In the
illustrated embodiment, hydrocarbon containing component 200 is a
silicon based compound (which may be referred to as a silane
coupling agent) that includes hydrocarbon ligand R and hydroxyl
groups 201. Surface 210 of the abrasive includes hydroxyl group
211. (Hydroxyl groups 201 and 211 may be part of silanol groups.)
It is believed that hydrogen bonds initially join hydrocarbon
containing component (a.k.a. silane coupling agent) 200 to surface
210 of the abrasive. A subsequent hydrolysis reaction between a
hydroxyl group of component 200 and hydroxyl group 211 of surface
210 may then take place. Such a reaction may release water while
component 200 is chemically bonded to surface 210 of the
abrasive--generating structure 220.
[0014] The composition of the present invention may be added to
slurries that are used to polish substrates. When making
semiconductor devices, a substrate may be polished with such a
slurry that comprises a hydrocarbon containing component that is
coupled to the surface of an abrasive. In one embodiment, the
substrate may comprise a metal. In another embodiment, the
substrate may comprise a dielectric layer.
[0015] The composition of the present invention may be added to
slurries that are used in different applications. Different
polishing operations may require different polish rates and may
tolerate defects to varying degree. Modifying the abrasive surface
with different hydrocarbon containing components (e.g., hydrocarbon
ligands with different lengths and functional groups) may give the
abrasive different properties--enabling one to create abrasives
that are suitable for slurries that are used in a variety of
applications.
[0016] In one example, a slurry that enables a relatively "soft"
polish may be desired, when polishing a relatively soft ultra low-k
dielectric layer, which traditional abrasives may damage.
Permanently modifying the surface of a colloidal silica abrasive,
by coupling to it a hydrocarbon ligand (e.g., a hydrocarbon chain)
of controlled length and functionality, may yield an abrasive that
enables a satisfactory soft polish. Such a ligand may provide a
soft stop for the abrasive, which may decrease the polish rate and
reduce the surface damage that may generate defects. In another
example, an abrasive's surface may be modified with a hydrocarbon
ligand that includes an oxidizing or reducing functional group. A
slurry that contains an abrasive, which is modified with a
hydrocarbon ligand that includes an oxidizing functional group, may
be particularly effective for the chemical mechanical polishing of
metal, e.g., copper.
[0017] These examples, which demonstrate how certain abrasive's
surfaces may be modified with hydrocarbon containing components
that are tailored for different polishing applications, are not
intended to be limiting. In this regard, the present invention
contemplates any composition that includes any abrasive to which a
hydrocarbon containing component is coupled.
[0018] The composition of the present invention enables the
development of slurries for use in chemical mechanical polishing
processes that remove metal or dielectric material at different
rates and that exhibit varying defect performance. Such a
composition may be generated in a relatively simple and inexpensive
way using a method that may be easily controlled. Note that the
method described above may enable slurry recycling, because the
modified abrasive can be regenerated, if the hydrocarbon containing
component is damaged or detached from the abrasive (e.g., during
the polishing process).
[0019] Although a few examples of components that may be used to
create the composition of the present invention are given here,
those skilled in the art will appreciate that others may be used
instead. In this regard, the composition is not limited to modified
silica abrasives, but instead includes any abrasive that may be
contained in slurries used in chemical mechanical polishing, e.g.,
alumina abrasives or any other oxide based abrasive. Moreover, the
composition is not limited to including the above described silane
based components, but may include a variety of other hydrocarbon
containing components that may be used to modify the surface of an
abrasive.
[0020] In addition to using the composition of the present
invention to enhance certain processes for making semiconductor
devices, it may be used in many other contexts. Although the
foregoing description has specified certain components that may be
included in the above described composition and has specified
certain steps and materials that may be used to make it, those
skilled in the art will appreciate that many modifications and
substitutions may be made. Accordingly, it is intended that all
such modifications, alterations, substitutions and additions be
considered to fall within the spirit and scope of the invention as
defined by the appended claims.
* * * * *