Abrading – Flexible-member tool – per se
Reexamination Certificate
2001-01-22
2002-05-07
Hail, III, Joseph J. (Department: 3723)
Abrading
Flexible-member tool, per se
C451S539000
Reexamination Certificate
active
06383065
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention concerns a polishing pad including a polishing pad substrate and catalyst having multiple oxidation states. This invention also concerns a method for using a catalyst containing polishing pad in conjunction with an oxidizing agent to chemically mechanically polish metal layers associated with integrated circuits and other electronic devices wherein the catalyst is a metal catalyst or a catalyst having multiple oxidation states.
(2) Description of the Art
A semiconductor wafer typically includes a substrate, such as a silicon or gallium arsenide wafer, on which a plurality of integrated circuits have been formed. Integrated circuits are chemically and physically integrated into a substrate by patterning regions in the substrate and layers on the substrate. The layers are formed of various materials having either a conductive, insulating or semiconducting nature. In order to produce devices in high yields, it is crucial to start with a flat semiconductor wafer. As a result, it is often necessary to polish semiconductor wafers to obtain flat surfaces. If the process steps of device fabrication are performed on a wafer surface that is not planar, various problems can occur which may result in a large number of inoperable devices. For example, in fabricating modern semiconductor integrated circuits, it is necessary to form conductive lines or similar structures above a previously formed structure. However, prior surface formation often leaves the top surface topography of a wafer highly irregular, with bumps, areas of unequal elevation, troughs, trenches and other similar types of surface irregularities. Global planarization of such surfaces is necessary to ensure adequate depth of focus during photolithography, as well as removing any irregularities and surface imperfections during the sequential stages of the fabrication process.
Although several techniques exist to ensure wafer surface planarity, processes employing chemical mechanical planarization or polishing techniques have achieved widespread usage. The polishing planarization techniques planarize the surface of wafers during the various stages of device fabrication and improve yield, performance and reliability. In general, chemical mechanical polishing (“CMP”) involves the circular motion of a wafer under a controlled downward pressure with a polishing pad saturated with a chemically-active polishing composition.
In order for CMP and other polishing techniques to provide effective planarization, the delivery of a polishing composition to the surface being polished becomes important. Chemical mechanical polishing compositions typically include a variety of ingredients including, oxidizing agents, film forming agents, corrosion inhibitors, abrasives, and so forth. Recently issued U.S. Pat. No. 5,958,288 discloses polishing compositions including catalysts having multiple oxidation states, the specification of which is incorporated herein by reference in it entirety.
The incorporation of abrasive particles into polishing pads is disclosed in several U.S. Patents including U.S. Pat. Nos. 5,849,051 and 5,849,052, the specifications of which are also incorporated herein by reference. In addition, solid metal catalysts have been incorporated into polishing pads as described in U.S. Pat. No. 5,948,697. The catalysts incorporated into polishing pads described in the '697 patent are used to catalyze semiconductor polishing upon application of an electrical bias to the semiconductor.
Despite these advances to chemical mechanical polishing compositions and polishing pads, there remains a need for polishing pads with improved polishing performance. There is also a need for new methods to polish integrated circuit layers and other electronic components that are reliable and reproducible.
SUMMARY OF THE INVENTION
This invention includes a polishing pad useful for chemical mechanical polishing comprising a polishing pad substrate and at least one catalyst having multiple oxidation states.
This invention also includes a polishing pad useful for chemical mechanical polishing comprising a polishing pad substrate, an abrasive, a soluble catalyst including a metal having multiple oxidization states selected from iron and copper that catalyzes the reaction of an oxidizing agent and the metal of a substrate metal feature being polished.
This invention further includes a method for polishing a metal feature on a substrate surface. The method includes the steps of preparing a polishing pad by combining a polishing pad substrate with at least one catalyst having multiple oxidation states. The catalyst containing polishing pad is then brought into contact with the metal feature of a substrate being polished. An oxidizing agent is applied to the catalyst containing polishing pad either before the pad is brought into contact with the metal feature being polished, or as the catalyst containing polishing pad is used to polish the substrate metal feature, or both. The catalyst containing polishing pad is moved in relationship to the substrate metal feature until a desired amount of metal is removed from the substrate metal feature.
DESCRIPTION OF THE CURRENT EMBODIMENT
The present invention relates to catalyst containing polishing pads that include a polishing pad substrate and at least one catalyst having multiple oxidation states. The catalyst containing polishing pads are useful for the chemical mechanical polishing (CMP) of one or more metal features associated with integrated circuits and other electronic devices.
The catalyst containing polishing pads of this invention include a polishing pad substrate and at least one catalyst. The polishing pad substrate may be any type of polishing pad substrate that are useful for CMP. Typical polishing pad substrates available for polishing applications, such as CMP, are manufactured using both soft and/or rigid materials and may be divided into at least four groups: (1) polymer-impregnated fabrics; (2) microporous films; (3) cellular polymer foams and (4) porous sintered-subtrates. For example, a pad substrate containing a polyurethane resin impregnated into a polyester non-woven fabric is illustrative of the first group. Polishing pad substrates of the second group consist of microporous urethane films coated onto a base material which is often an impregnated fabric of the first group. These porous films are is composed of a series of vertically oriented closed end cylindrical pores. Polishing pad substrates of the third group are closed cell polymer foams having a bulk porosity which is randomly and uniformly distributed in all three dimensions. Polishing pad substrates of the fourth group are opened-celled, porous substrates having sintered particles of synthetic resin. Representative examples of polishing pad substrates useful, in the present invention, are described in U.S. Pat. Nos. 4,728,552, 4,841,680, 4,927,432, 4,954,141, 5,020,283, 5,197,999, 5,212,910, 5,297,364, 5,394,655, 5,489,233 and 6,062,968, each of the specifications of which are incorporated herein in their entirety by reference.
The polishing pad substrates used in the present invention may be any one of the substrates described above. In addition, the polishing pad substrate may be made from a material other than a polymer such as cellulose fabric or any other materials that are known in the art to be useful for chemical mechanical polishing. What is important is that the polishing substrate chosen must be capable of being combined with at least one catalyst to form a catalyst containing polishing pad.
The polishing pads of this invention include at least one catalyst. The purpose of the catalyst is to transfer electrons from the metal of a substrate metal feature being oxidized to the oxidizing agent (or analogously to transfer electrochemical current from the oxidizer to the metal). The catalyst or catalysts chosen may be metallic, non-metallic, or a combination thereof and the catalyst must have multiple oxidation states. That is the catalyst must be able to
Grumbine Steven K.
Mueller Brian L.
Streinz Christopher C.
Cabot Microelectronics Corporation
Hail III Joseph J.
Thomas David B.
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