Silica particles for polishing and a polishing agent

Details Silica particles for polishing and a polishing agent Silica particles for polishing and a polishing agent

2002-11-12

2003-11-25

Marcheschi, Michael (Department: 1755)

Abrasive tool making process, material, or composition

With inorganic material

Clay, silica, or silicate

C106S003000, C106S482000, C423S335000

Reexamination Certificate

active

06652612

ABSTRACT:

TECHNICAL FIELD
The present invention relates to silica particles for polishing usefully available in forming a metal wiring layer in a semiconductor integrated circuit for smoothing a surface of a substrate thereof and a polishing agent (or a polishing material) containing the particles for polishing.
BACKGROUND TECHNOLOGY
Various types of integrated circuits are used in computers and various types of electronic equipments, and a higher degree of integration is required in association with the tendency for higher performances of the circuits.
In the circumstances as described above, multi-layered wiring is used, for instance, in semiconductor integrated circuits to improve the integration degree of semiconductor integrated circuits, and the multi-layered wiring is usually manufactured by forming a thermally oxidized film as a first insulating film on a substrate comprising, for instance, silicon; then forming a first wiring layer comprising, for instance, an aluminum film; coating an inter-layer insulating film comprising, for instance, a silica film or a silicon nitride film by means of such methods as the CVD method or plasma CVD method; forming a silica insulating film for planarizing the inter-layer insulating film by means of the SOG method; coating a second insulating film on the silica insulating film, if required; and finally forming a second wiring layer.
In the wiring comprising an aluminum film is sometimes oxidized with the resistance value increased in spattering for forming the multi-layered wiring, which may in turn causes a conduction fault. Further as the wiring width can not be made smaller, there has been a limit in forming an integrated circuit with a higher integration degree. Further, recently in a long range wiring such as a clock line or a data bus line, the wiring resistance becomes larger in association with increase of the chip size, and an electric signal propagation delay time (RC delay time=resistance×capacity) disadvantageously increases. To cope with this problem, it is required to provide wiring with a material having a lower resistance value.
It has also been proposed to use Cu in place of Al or aluminum alloy used in the conventional technology for wiring, and for instance, there has been known a method, in which a wiring groove is previously prepared in an insulating film on a substrate and then a Cu wiring is formed by the electrolytic plating method or the CVD method.
In the wiring pattern formation using such material as Cu, machining by the dry etch method can hardly be performed, so that the Damascene process using a chemical and mechanical polishing method (described as CMP method hereinafter), and in this case, a wiring groove is previously formed in an insulating film on a substrate, and then a copper wire is buried in the wiring groove by means of the electrolytic plating method or the CVD method with an upper edge face polished by the CMP method for planarizing it to form the wiring. For instance, an inter-wiring layer film (an insulating film) is formed on a surface such as a silicon wafer with a groove pattern for metal wiring formed thereon, and further a barrier metal layer comprising, for instance, TaN is formed by the spattering method or the like, if necessary, and finally a copper wire for the metal wiring is provided by the CVD method or other appropriate method. When the barrier metal layer comprising such material as TaN is provided, such troubles as lowering of the insulating capability of the inter-layer insulating film caused by dispersion of or corrosion by copper or other impurities can be prevented, and further adhesiveness between the interlayer insulating film and copper can be enhanced.
Then the unnecessary copper metal film and barrier metal film (which may sometimes be called as a sacrifice layer) formed outside the groove are polished by the CMP method, and at the same time the upper surface of the substrate is planarized as much as possible to leave a metal film in the groove, and thus the copper wiring and circuit pattern being formed.
In the CMP method, generally a polishing pad is placed on a round platen having a rotating mechanism, a work to be polished is rotated in the state where a polishing material is being dripped from a position above a center of the polishing pad, the work is pressed and contacted to the polishing pad, and the copper and barrier metal layers on the common plane are polished away.
As irregularities due to a groove pattern for wiring formed on the under insulating film is present on a surface of the work to be polished, the surface is required to be polished down to the common plane by removing mainly the convex sections for obtaining a planarized surface.
The polishing material used in the CMP method generally comprises spherical particles for polishing comprising oxides of metals such as silica and alumina and having the average particle diameter of about 200 nm; an oxidizing agent for raising the rate of polishing the metals used for wiring and circuit patterns, and an additive such as an organic acid; and a solvent such as deionized water.
In the conventional technology of polishing with silica or alumina, there is the disadvantage that scratches such as flaws or stripes still remain, or are newly generated after the polishing process.
Japanese Patent Laid-Open Publication No. HEI 9-324174 discloses the composite particles comprising organic materials and inorganic materials usefully available for suppressing generation of scratches, and the composite particles contain an organic polymer skeletal structure and a polysiloxane skeletal structure containing in the molecular structure an organic silicon directly and chemically bonding to at least one carbon atom in the organic polymer skeletal structure, and a content of SiO
2
constituting the polysiloxane skeletal structure is 25 weight % and more.
Hardness of the composite particles comprising organic and inorganic materials described above varies according to a content of SiO
2
constituting the polysiloxane skeletal structure, and in a case where a content of organic polymer is large and a content of SiO
2
is small, scratches are generated little, but the required polishing rate is low. On the contrary, in a case where a content of organic polymer is small and a content of SiO
2
is large, the polishing rate is high, but starches will easily be generated. Even if the SiO
2
content is made large within the range where scratches are not generated, the sufficient polishing rate can not be achieved, which is a bottleneck in this technology.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide particles for polishing capable of suppressing generation of the so-called scratches and also polishing and planarizing a surface of a substrate at a sufficient polishing rate and also to provide a polishing agent or a polishing material containing the particles for polishing.
The silica particles for polishing according to the present invention are characterized in that the average particle diameter is in the range from 5 to 300 nm and the carbon content is in the range from 0.5 to 5 weight %.
The silica particles for polishing should preferably have the 10%-compressive elasticity modulus in the range from 500 to 3000 kgf/mm
2
. The Na content of silica particles for polishing should preferably be less than 100 ppm as converted to Na.
A polishing agent or a polishing material according the present invention contains the silica particles for polishing.
BEST MODE FOR CARRYING OUT THE INVENTION
[Particle for polishing]
The average particle diameter of the silica particles for polishing according to the present invention is preferably in the range from 5 to 300 nm, and more specifically in the range from 10 to 200 nm, although it depends on such factors as required polishing rate, and polishing precision. When the average particle diameter is less than 5 nm, stability of the dispersion liquid of silica particles is apt to become unstable, and the particle size is too small to realize the suf

Affiliated with

Also associated with

Rating

Silica particles for polishing and a polishing agent does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Silica particles for polishing and a polishing agent, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silica particles for polishing and a polishing agent will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3130452