Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Of specified material other than unalloyed aluminum
Reexamination Certificate
2000-07-05
2003-11-11
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Of specified material other than unalloyed aluminum
C438S747000
Reexamination Certificate
active
06646348
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns chemical mechanical polishing compositions and slurries that are useful for polishing one or more features associated with a substrate. The polishing compositions of this invention include at least one silane composition that remains in solution as well as at least one abrasive. This invention also includes a method of applying a silane composition to an abrasive pad to form a silane modified abrasive pad. This invention also includes methods for using polishing compositions of this invention to polish substrate features.
DESCRIPTION OF THE ART
Integrated circuits are made up of millions of active devices formed in or on a silicon substrate. The active devices, which are initially isolated from one another, are interconnected to form functional circuits and components. The devices are interconnected through the use of multilevel interconnections. Interconnection structures normally have a first layer of metallization, an interconnection layer, a second level of metallization, and sometimes a third and subsequent level of metallization. Interlevel dielectrics such as doped and undoped silicon dioxide (SiO
2
), or low-k dielectrics tantalum nitride are used to electrically isolate the different levels of metallization in a silicon substrate or well. The electrical connections between different interconnection levels are made through the use of metallized vias. U.S. Pat. No. 5,741,626, which is incorporated herein by reference, describes a method for preparing dielectric tantalum nitride layers.
In a similar manner, metal contacts are used to form electrical connections between interconnection levels and devices formed in a well. The metal vias and contacts may be filled with various metals and alloys including titanium (Ti), titanium nitride (TiN), tantalum (Ta), aluminum copper (Al—Cu), aluminum silicon (Al—Si), copper (Cu), tungsten (W), and combinations thereof. The metal vias and contacts generally employ an adhesion layer comprising compounds such as titanium nitride (TiN), titanium (Ti), tantalum (Ta), tantalum nitride (TaN) or combinations thereof to adhere the metal layer to the SiO
2
substrate. At the contact level, the adhesion layer acts as a diffusion barrier to prevent the filled metal and SiO
2
from reacting.
In many semiconductor manufacturing processes, metallized vias or contacts are formed by a blanket metal deposition followed by a chemical mechanical polish (CMP) step. In a typical process, via holes are etched through an interlevel dielectric (ILD) to interconnection lines or to a semiconductor substrate. Next, a thin adhesion layer such as tantalum nitride and/or tantalum is generally formed over the ILD and is directed into the etched via hole. Then, a metal film is blanket deposited over the adhesion layer and into the via hole. Deposition is continued until the via hole is filled with the blanket deposited metal. Finally, the excess metal is removed by chemical mechanical polishing, (CMP) to form substrate surface features known as metal vias. Processes for manufacturing and/or CMP of vias are disclosed in U.S. Pat. Nos. 4,671,851, 4,910,155 and 4,944,836.
In a typical chemical mechanical polishing process, a substrate is placed in direct contact with a rotating polishing pad. A carrier applies pressure against the backside of the substrate. During the polishing process, the pad and table are rotated while a downward force is maintained against the substrate back. A chemically reactive polishing composition is applied to the pad during polishing. The polishing composition may contain an abrasive to form what is typically referred to as a “slurry”. Alternatively, the polishing pad can including abrasive. In either circumstance, the polishing composition initiates the polishing process by chemically reacting with the surface of the substrate feature being polished. The polishing process is facilitated by the rotational movement of the pad relative to the substrate all the while delivering polishing composition/slurry to the wafer/pad interface. Polishing is continued in this manner until the desired amount film on the feature is removed. Polishing composition formulation is an important factor in the CMP step. The polishing composition should be tailored to provide effective polishing to metal layers at desired polishing rates while minimizing surface imperfections, defects and corrosion and erosion. Furthermore, the polishing composition may be used to provide controlled polishing selectivities to other thin-film materials used in current integrated circuit technology such as titanium, titanium nitride, tantalum, tantalum nitride, and the like.
There are various mechanisms disclosed in the prior art by which substrate surface features can be polished with CMP. The compositions surface may be polished using a slurry in which a surface film is not formed in which case the process proceeds by mechanical removal of metal particles and their dissolution in the slurry. In such a mechanism, the chemical dissolution rate should be slow in order to avoid wet etching. A more preferred mechanism is, however, one where a thin abradable layer is continuously formed by reaction between the metal surface and one or more components in the slurry such as a complexing agent and/or a film forming layer. The thin abradable layer is then removed in a controlled manner by mechanical action. Once the mechanical polishing process has stopped a thin passive film remains on the surface and controls the wet etching process. Controlling the chemical mechanical polishing process is much easier when a CMP slurry polishes using this mechanism.
Current copper containing substrates that are polished using chemical mechanical polishing also use Ta and TaN adhesion layers. Ta and TaN are chemically very passive and mechanically very hard and thus difficult to remove by polishing. Thus, there remains a need for polishing compositions that are useful for polishing substrates including tantalum while having little detrimental effect on previously polished copper features.
SUMMARY OF THE INVENTION
It is an object of this invention to provide polishing compositions that are able to effectively polish surface features of a substrate such as an integrated circuit.
It is a further object of this invention to provide polishing compositions for integrated circuits that are able to polish surface features with acceptable defectivity.
In one embodiment, this invention includes chemical mechanical polishing solution comprising at least one silane compound in solution and at least one abrasive.
In another embodiment, this invention includes aqueous chemical mechanical polishing compositions comprising at least one abrasive and at least one soluble silane compound in solution wherein the soluble silane compound is present in the solution in an amount ranging from about 0.02 to about 5.0 wt %, wherein the silane compound in solution has the following formula
Y—Si—(X
1
X
2
R)
including dimers, trimers and oligomers thereof, wherein one substituent selected from R, X
1
, X
2
and Y is selected from hydroxy or a hydrolyzable moiety and wherein three substituents selected from R, X
1
, X
2
and Y are non-hydrolyzable moieties and wherein at least one of the non-hydrolyzable substituents is selected from the group consisting of alkyl or functionalized alkyl each having from 2 to 25 carbon atoms.
In still another embodiment, this invention includes a method for polishing a feature associated with a substrate surface. The method includes moving the substrate into contact with a polishing pad such that the substrate surface feature contacts the polishing pad. Next, the polishing pad is moved in relationship to the substrate surface. A polishing composition is applied to the polishing pad during polishing wherein the polishing composition is a solution comprising at least one silane compound in solution.
DESCRIPTION OF THE CURRENT EMBODIMENT
The present invention relates to chemical mechanical polishing compositions and to methods for using the compositions to
Grumbine Steven K.
Wang Shumin
Cabot Microelectronics Corporation
Hoang Quoc
Nelms David
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