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Polishing pad and method of making the same

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Polishing pad and method of making the same


The disclosure is directed to polishing pads with porous polishing layers, methods of making such polishing pads, and methods of using such pads in a polishing process. The polishing pad includes a compliant layer having first and second opposing sides and a porous polishing layer disposed on the first side of the compliant layer. The porous polishing layer includes a crosslinked network comprising a thermally cured component and a radiation cured component, wherein the radiation cured component and the thermally cured component are covalently bonded in the crosslinked network. The porous polishing layer also includes polymer particles dispersed within the crosslinked network, wherein the polymer particles comprise at least one of thermoplastic polymers or thermoset polymers. The porous polishing layer typically also includes closed cell pores dispersed within the crosslinked network.
Related Terms: Covalent Polymer

Inventors: Naichao Li, William D. Joseph
USPTO Applicaton #: #20130012108 - Class: 451 59 (USPTO) - 01/10/13 - Class 451 
Abrading > Abrading Process >Utilizing Nonrigid Tool

Inventors:

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The Patent Description & Claims data below is from USPTO Patent Application 20130012108, Polishing pad and method of making the same.

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CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Nos. 61/288,982, filed Dec. 22, 2009, and 61/422,442, filed Dec. 13, 2010, the disclosures of which are incorporated by reference herein in their entirety.

BACKGROUND

During the manufacture of semiconductor devices and integrated circuits, silicon wafers are iteratively processed through a series of deposition and etching steps to form overlying material layers and device structures. A polishing technique known as chemical mechanical planarization (CMP) may be used to remove surface irregularities (such as bumps, areas of unequal elevation, troughs, and trenches) remaining after the deposition and etching steps, with the objective of obtaining a smooth wafer surface without scratches or depressions (known as dishing), with high uniformity across the wafer surface.

In a typical CMP polishing process, a substrate such as a wafer is pressed against and relatively moved with respect to a polishing pad in the presence of a working liquid that is typically a slurry of abrasive particles in water and/or an etching chemistry. Various CMP polishing pads for use with abrasive slurries have been disclosed, for example, U.S. Pat. Nos. 5,257,478 (Hyde et al.); 5,921,855 (Osterheld et al.); 6,126,532 (Sevilla et al.); 6,899,598 (Prasad); and 7,267,610 (Elmufdi et al.). Fixed abrasive polishing pads are also known, as exemplified by U.S. Pat. No. 6,908,366 (Gagliardi), in which the abrasive particles are generally fixed to the surface of the pad, often in the form of precisely shaped abrasive composites extending from the pad surface. Recently, a polishing pad having a multiplicity of polishing elements extending from a compressible underlayer was described in Int. App. Publ. No. WO/2006057714 (Bajaj). Although a wide variety of polishing pads are known and used, the art continues to seek new and improved polishing pads for CMP, particularly in CMP processes where larger die diameters are being used, or where higher levels of wafer surface flatness and polishing uniformity are required.

SUMMARY

The present disclosure provides porous polishing pads with a polishing layer having a thermally cured component and a radiation cured component and methods of making such polishing pads. Pores are incorporated into the polishing layer through the use of polymer particles. The pores in the porous polishing pads disclosed herein are closed cell pores that generally have lower pore size non-uniformity and smaller pore size than the pores of conventional thermally cured polishing pads. The control over pore size and distribution may be advantageous, for example, for the polishing performance of the polishing pad.

In one aspect, the present disclosure provides a polishing pad comprising:

a compliant layer having first and second opposing sides; and

a porous polishing layer disposed on the first side of the compliant layer, the porous polishing layer comprising: a crosslinked network comprising a thermally cured component and a radiation cured component, wherein the radiation cured component and the thermally cured component are covalently bonded in the crosslinked network; polymer particles dispersed within the crosslinked network; and closed cell pores dispersed within the crosslinked network. In some embodiments, the polishing pad further comprises a support layer interposed between the compliant layer and the porous polishing layer.

In another aspect, the present disclosure provides a method of making a polishing pad, the method comprising:

providing a composition comprising a thermally curable resin composition, a radiation curable resin composition, and polymer particles;

forming pores in the composition;

positioning the composition on a support layer; and

forming a porous polishing layer on the support layer by exposing the composition to radiation to at least partially cure the radiation curable resin composition and heating the composition to at least partially cure the thermally curable resin composition. In some embodiments, the method further comprises adhesively bonding a compliant layer to a surface of the support layer opposite the porous polishing layer.

In a further aspect, the present disclosure provides a method of polishing comprising:

contacting a surface of a substrate with the porous polishing layer of the polishing pad according to the present disclosure; and

relatively moving the polishing pad with respect to the substrate to abrade the surface of the substrate.

Exemplary embodiments of polishing pads according to the present disclosure have various features and characteristics that enable their use in a variety of polishing applications. In some embodiments, polishing pads of the present disclosure may be particularly well suited for chemical mechanical planarization (CMP) of wafers used in manufacturing integrated circuits and semiconductor devices. In some embodiments, the polishing pad described in this disclosure may provide some or all of the following advantages.

For example, in some embodiments, a polishing pad according to the present disclosure may act to better retain a working liquid used in the CMP process at the interface between the polishing surface of the pad and the substrate surface being polished, thereby improving the effectiveness of the working liquid in augmenting polishing. In other exemplary embodiments, a polishing pad according to the present disclosure may reduce or eliminate dishing and/or edge erosion of the wafer surface during polishing. In some exemplary embodiments, use of a polishing pad according to the present disclosure in a CMP process may result in improved within wafer polishing uniformity, a flatter polished wafer surface, an increase in edge die yield from the wafer, and improved CMP process operating conditions and consistency. In further embodiments, use of a polishing pad according to the present disclosure may permit processing of larger diameter wafers while maintaining the required degree of surface uniformity to obtain high chip yield, processing of more wafers before conditioning of the pad surface is needed in order to maintain polishing uniformity of the wafer surfaces, or reducing process time and wear on the pad conditioner.

In this disclosure:

“Pore size non-uniformity” refers to the standard deviation of the pore size mean divided by the mean pore size multiplied by 100.

The term “polyurethane” refers to a polymer having more than one urethane linkage (—NH—C(O)—O—), urea linkage (—NH—C(O)—NH— or —NH—C(O)—N(R)—, wherein R can be hydrogen, an aliphatic, cycloaliphatic or aromatic group), biuret, allophanate, uretdione, or isocyanurate linkage in any combination.

The term “(meth)acrylate” refers to acrylates and methacrylates, which can include urethane acrylates, methacrylates and combinations of acrylates and methacrylates.

The term “polymeric” refers to a molecule having a structure that includes the multiple repetition of units derived from molecules of low relative molecule mass. The term “polymeric” includes “oligomeric”.

Terms such as “a”, “an” and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terms “a”, “an”, and “the” are used interchangeably with the term “at least one”.

The phrases “at least one of” and “comprises at least one of” followed by a list refers to any one of the items in the list and any combination of two or more items in the list.

All numerical ranges are inclusive of their endpoints and non-integral values between the endpoints unless otherwise stated.

Various aspects and advantages of exemplary embodiments of the disclosure have been summarized. The above Summary is not intended to describe each illustrated embodiment or every implementation of the present disclosure. The Drawings and the Detailed Description that follow more particularly exemplify some embodiments of the disclosure.

BRIEF DESCRIPTION OF DRAWINGS

Exemplary embodiments of the present disclosure are further described with reference to the appended figures, wherein:

FIGS. 1A and 1B are micrographs of a cross-section and top view, respectively, of a porous polishing pad in the prior art;

FIG. 2 is a schematic side view of one embodiment of a polishing pad according to the present disclosure;

FIG. 3 is a side view of a polishing pad having projecting polishing elements according to another embodiment of the present disclosure;

FIG. 4 is a side view of a polishing pad having projecting polishing elements according to yet another embodiment of the present disclosure;

FIGS. 5A and 5B are micrographs of a cross-section and top view, respectively, of the cured composition of Example 2 useful for forming polishing layers according to the present disclosure;

FIGS. 6A and 6B are micrographs of a cross-section and a top view, respectively, of the cured composition of Comparative Example 3;

FIGS. 7A and 7B are micrographs of a cross-section and top view, respectively, of the cured composition of Example 15 useful for forming polishing layers according to the present disclosure; and

FIG. 8 is a micrograph of a cross-section view of the cured composition of Example 11 useful for forming polishing layers according to the present disclosure.

Like reference numerals in the drawings indicate like elements. The drawings herein as not to scale, and in the drawings the components of the polishing pads are sized to emphasize selected features.



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Polishing pad and production method therefor, and production method for semiconductor device
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stats Patent Info
Application #
US 20130012108 A1
Publish Date
01/10/2013
Document #
13518475
File Date
12/20/2010
USPTO Class
451 59
Other USPTO Classes
451539, 451532, 451529, 51296
International Class
/
Drawings
6


Covalent
Polymer


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