Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
2002-01-11
2003-09-02
Morgan, Eileen P. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C451S036000, C451S287000, C051S295000, C051S308000
Reexamination Certificate
active
06612911
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention pertains to polishing systems and methods for polishing substrates.
BACKGROUND OF THE INVENTION
The trend in the semiconductor industry continues to concentrate on reducing the size of semiconductor devices while improving the planarity of their surfaces. More specifically, it is desirable to achieve a surface of even topography by decreasing the number and allowable size of surface imperfections. A smooth topography is sought-after because it is difficult to lithographically image and pattern layers applied to rough surfaces. A conventional way of planarizing the surfaces of these devices is to polish them with a polishing system.
During polishing, it is often useful to polish one wafer surface material faster than another. For example, in shallow-trench isolation (STI), it is important to polish away an overlayer of silicon dioxide, until a silicon nitride layer is exposed, and then to remove as little of the exposed silicon nitride layer as possible. This can be accomplished by a polishing system that polishes away silicon dioxide at a faster rate than silicon nitride. The difference in the rate of polishing between two materials, such as silicon dioxide and silicon nitride, is called selectivity. Increased silicon dioxide-silicon nitride selectivity is a highly desirable property in STI polishing systems.
An accepted method of polishing (e.g., planarizing) semiconductor devices involves polishing the surface of the semiconductor with a polishing composition and/or a polishing pad, such as is accomplished by chemical-mechanical polishing (CMP). In a typical CMP process, a wafer is pressed against a polishing pad in the presence of a slurry under controlled chemical, pressure, velocity, and temperature conditions. The slurry generally contains small, abrasive particles that abrade the surface of the wafer in a mixture with chemicals that etch and/or oxidize the newly formed surface of the wafer. The polishing pad generally is a planar pad made from a continuous phase matrix material such as polyurethane. Thus, when the polishing pad and/or the wafer moves with respect to the other, material is removed from the surface of the wafer mechanically by the abrasive particles and chemically by the etchants and/or oxidants in the slurry.
While the aqueous chemicals desirably react chemically with the substrate, they also are reactive with the abrasive particles. This reaction can “soften” the abrasive particle surfaces, rendering the abrasive less abrasive. Moreover, the reaction of the chemical component with the abrasive particle surface lowers the concentration of that component available for reaction with the substrate surface during polishing. As a result, the polishing performance of premixed CMP slurries may not be optimal for the polishing of solid surfaces, including IC wafer surfaces, rigid disk surfaces, glass surfaces, magnetic media, etc. Furthermore, because CMP slurries must be stable for the extended periods over which they arc typically stored before use, the chemical additives available for use in slurries is limited by their reactivity with other components in the slurry. This consideration also limits the concentration of additives that can be incorporated into slurries.
Thus, there remains a need for improved polishing systems and methods. The invention provides such a polishing system and method These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
BRIEF SUMMARY OF THE INVENTION
The invention provides polishing systems that comprise a liquid carrier, an alkali metal ion, a compound comprising an amine group and at least one polar moiety, wherein the polar moiety contains at least one oxygen atom (hereinafter referred to as an “amine-containing, compound”), and a polishing pad and/or an abrasive. The abrasive can be dispersed in the liquid carrier of the polishing system or bound to the polishing pad. In a first embodiment, the alkali metal ion and the amine-containing compound desirably are present in a concentration such that the total ion concentration of the polishing system is above the critical coagulation concentration. In a second embodiment, the polishing system comprises about 0.05 wt. % to about 0.15 wt. % KOH and about 0.4 M to about 0.8 M of the amine-containing compound. The invention further provides polishing a portion of a substrate with a polishing system of the invention, preferably beginning about 6 hours or less after the polishing system is prepared.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides polishing systems and methods for polishing a substrate. Generally, the polishing systems comprise, consist essentially of, or consist of (a) a liquid carrier, (b) an alkali metal ion, (c) a compound comprising an amine group and at least one polar moiety, wherein the polar moiety contains at least one oxygen atom, and (d) a polishing pad and/or an abrasive. In a first embodiment, the polishing system has a total ion concentration, which is above the critical coagulation concentration. In a second embodiment, the polishing system comprises about 0.05 wt. % to about 0. 5 wt. % KOH and about 0.4 M to about 0.8 M of the compound comprising an amine group and at least one polar moiety, wherein the polar moiety contains at least one oxygen atom. The polishing methods generally comprise contacting a surface of a substrate with a polishing system and polishing at least a portion of the substrate. In a first embodiment, the polishing system used in the polishing method is one of the aforementioned polishing systems. In a second embodiment, the polishing system used in the polishing method comprises (a) a liquid carrier, (b) an alkali metal ion, (c) a compound comprising an amine group and at least one polar moiety, wherein the polar moiety contains at least one oxygen atom, and (d) a polishing pad and/or an abrasive, and a portion of the substrate is polished with the polishing system before the polishing system components reach a chemical equilibrium after the system is prepared.
Typically, each polishing system is used about 6 hours or less after the polishing system is prepared, which generally will be before the polishing system reaches a chemical equilibrium. Preferably, the polishing system is used about 4 hours or less (e.g., about 2 hours or less, about 1 hour or less, about 30 minutes or less, about 10 minutes or less, about 5 minutes or less, or even about 1 minute or less) after the polishing system is prepared. Indeed, the polishing system can be used seconds (e.g., about 30 seconds, or less or about 10 seconds or less) after the polishing system is prepared, such as when the polishing system components are mixed very near or at the point-of-use of the polishing system (e.g., on the polishing pad and/or substrate being polished).
The term “component” as used herein includes individual ingredients (e.g., acids, bases, oxidizers, water, etc.) as well as any combination of ingredients (e.g., aqueous compositions, abrasive slurries, mixtures and solutions of oxidizers, acids, bases, complexing agents, etc.) that are stored separately and combined to form a polishing system.
The polishing systems and methods of the invention can be used to polish any suitable substrate. Suitable substrates are typically wafers used in the semiconductor industry that are in need of polishing or planarizing. They comprise, for example, a metal, metal oxide, metal composite, metal alloy, or mixtures thereof. The substrate can comprise metals such as copper, aluminum, titanium, tungsten, gold, and combinations (e.g., alloys or mixtures) thereof. The substrate also can comprise metal oxides such as, alumina, silica, titania, ceria, zirconia, germania, magnesia, and co-formed products thereof, and mixtures thereof. In addition, the substrate can comprise metal composites and/or alloys such as metal nitrides (e.g., silicon nitride, tantalum nitride, titanium nitride, and tungsten nitride), metal carbides (e.
Bogush Gregory H.
Carter Phillip
Chamberlain Jeffrey P.
De Rege Francesco M.
Mueller Brian L.
Cabot Microelectronics Corporation
Morgan Eileen P.
LandOfFree
Alkali metal-containing polishing system and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Alkali metal-containing polishing system and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Alkali metal-containing polishing system and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3099936