CN102310366B - Chemical-mechanical polishing pads with low-defect monolithic windows - Google Patents

Abstract

The invention discloses a chemical mechanical polishing pad. The chemical mechanical polishing pad comprises a polishing layer, wherein the polishing layer comprises an overall window and a polishing surface; the polishing surface is suitable to be used for polishing a substrate selected from a magnetic substrate, an optical substrate and a semiconductor substrate; and the preparation of the overall window provides improved defect performance in a polishing process. The invention also provides a method for polishing the substrate by using the chemical mechanical polishing pad.

Description

Chemical-mechanical polishing pads with low-defect monolithic windows

technical field

The present invention generally relates to the field of chemical mechanical polishing. In particular, the invention relates to chemical mechanical polishing pads having low defect integral windows. The present invention also relates to a method of chemical mechanical polishing of a substrate using a chemical mechanical polishing pad having a low defect integral window.

Background technique

In the manufacture of integrated circuits and other electronic devices, layers of conductive, semiconducting, and dielectric materials need to be deposited on or removed from the surface of a semiconductor wafer. Thin layers of conductive, semiconducting, and dielectric materials can be deposited using a variety of deposition techniques. Conventional deposition techniques in modern wafer processing include physical vapor deposition (PVD) (also known as sputtering), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and electroplating (ECP).

As layers of material are sequentially deposited and removed, the uppermost surface of the wafer becomes uneven. Wafers require planarization because subsequent semiconductor processing, such as metallization, requires the wafer to have a flat surface. Planarization can be used to remove unwanted surface topography and surface defects such as rough surfaces, agglomerated material, lattice disruption, scratches and contaminated layers or materials.

Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a conventional technique used to planarize substrates such as semiconductor wafers. In conventional CMP, a wafer is mounted on a carrier assembly, positioned in contact with a polishing pad in the CMP apparatus. The support assembly provides a controlled pressure on the wafer against the polishing pad. The polishing pad is moved (eg, rotated) relative to the wafer by an external driving force. At the same time, a chemical composition ("slurry") or other polishing solution is provided between the wafer and the polishing pad. Thus, the surface of the wafer is polished to planarize by the chemical and mechanical action of the polishing pad surface and the slurry.

A problem in chemical mechanical polishing is determining when a substrate has been polished to the desired degree. Methods have been developed to determine the endpoint of polishing in situ. One such method uses a laser interferometer, which uses light generated by a laser to determine the dimensions of the substrate. Accordingly, chemical mechanical polishing pads have been developed that have features that facilitate the optical determination of dimensional characteristics of substrates. For example, US Patent No. 5,605,760 discloses a polishing pad in which at least a portion of the polishing pad is transmissive to a range of wavelengths of laser light. In one embodiment, the polishing pad includes a transparent window disposed within an otherwise partially opaque polishing pad. The windows may be rods or inserts of clear polymer material disposed within the molded polishing pad. The sticks or inserts can be inserts molded into the polishing pad (i.e., integral windows), or can fit into cutouts in the polishing pad (i.e., insert-in-place windows) after the molding operation. .

Conventional chemical mechanical polishing pads that include an insert seating window are prone to leakage of polishing media at the interface between the insert seating window and the remainder of the chemical mechanical polishing pad. This leaked polishing media can penetrate into the polishing layer, interlayer or sub-pad layer, causing, for example, regional differences in the compressibility of the polishing layer, leading to increased polishing defects. Leaked polishing media can also penetrate through the polishing pad and cause damage to the polishing equipment.

Conventional chemical mechanical polishing pads that include an integral window are prone to increased polishing defects relative to the insert seating window because as the pad ages, the window protrudes outward from the pad, causing polishing defects (e.g. scratches to polished substrates).

Accordingly, there is a need for an improved chemical mechanical polishing pad including a window that reduces the leakage problems typically associated with insert-in-place windows, as well as the polishing defect problems associated with conventional integral windows.

Contents of the invention

In one aspect of the present invention, a chemical mechanical polishing pad is provided, comprising: a polishing layer comprising a polishing surface and an integral window; the integral window is incorporated in the polishing layer; the integral window is a curing agent A polyurethane reaction product with an isocyanate-terminated prepolymer polyol; the curing agent comprises a curing agent amine moiety capable of interacting with unreacted NCO moieties contained in the isocyanate-terminated prepolymer polyol react to form a monolithic window; provide the curing agent and isocyanate-terminated prepolymer polyol with a stoichiometric ratio of amine moieties to unreacted NCO moieties of 1:1 to 1:1.25; the porosity of the monolithic window is < 0.1% by volume; the compression set of the integral window is 5-25%; wherein the polishing surface is suitable for polishing a substrate selected from magnetic substrates, optical substrates and semiconductor substrates.

In another aspect of the present invention, there is provided a method for performing chemical mechanical polishing on a substrate selected from a magnetic substrate, an optical substrate, and a semiconductor substrate, the method comprising: providing a chemical mechanical polishing apparatus, the The apparatus includes a platen; providing at least one substrate selected from a magnetic substrate, an optical substrate, and a semiconductor substrate; selecting a chemical mechanical polishing pad including a polishing layer including an integral window formed therein , the compression deformation of the integral window is 5-25%; the chemical mechanical polishing pad is installed on the platen; the polishing surface of the polishing layer is used to polish the at least one seed substrate.

In another aspect of the present invention, there is provided a method for performing chemical mechanical polishing on a substrate selected from a magnetic substrate, an optical substrate, and a semiconductor substrate, the method comprising: providing a chemical mechanical polishing apparatus, the The equipment comprises a platen; providing at least one substrate selected from a magnetic substrate, an optical substrate and a semiconductor substrate; selecting the chemical mechanical polishing pad according to claim 1; and installing the chemical mechanical polishing pad on the platen on; polishing the at least one substrate with the polishing surface of the polishing layer.

Detailed ways

As used herein and in the appended claims, the term "polishing media" includes particle-containing polishing fluids and non-particle-free polishing solutions, such as non-abrasive and reactive liquid polishing fluids.

As used herein and in the appended claims, the term "poly(urethane)" includes: (a) polyurethanes formed by the reaction of (i) isocyanates with (ii) polyols (including diols); Poly(ammonia) formed by reaction of (i) isocyanates with (ii) polyols (including diols) and (iii) water, amines (including diamines and polyamines), or a combination of water and amines (including diamines and polyamines) ester).

The chemical mechanical polishing pad of the present invention comprises a polishing layer comprising a polishing surface and an integral window; the integral window is incorporated in the polishing layer; the integral window is a combination of a curing agent and an isocyanate-terminated prepolymer polyol a polyurethane reaction product; the curing agent comprises a curing agent amine moiety capable of reacting with unreacted NCO moieties contained in the isocyanate-terminated prepolymer polyol to form an integral window; A stoichiometric ratio of unreacted NCO moieties of 1:1 to 1:1.25 provides the cured and isocyanate-terminated prepolymer polyol; the integral window has a porosity of <10.0 vol%, preferably <0.1 vol%, more Preferably 0.000001 to <0.1 vol%, more preferably 0.000001 to <0.9 vol%, most preferably 0.000001-0.05 vol%, the compression set of the integral window is 5-25%, preferably 5-20%, more preferably 5- 15%, more preferably 5-10%, most preferably 5-8%; wherein, the polishing surface is suitable for polishing a substrate selected from magnetic substrates, optical substrates and semiconductor substrates.

Preferably, the curing agent and isocyanate-terminated prepolymer polyol are provided in suitable ratios such that the stoichiometric ratio of _NH2 to unreacted NCO is 1:1 to 1:1.25, preferably 1:1 to 1:1 1.15, more preferably 1:1 to 1:1.10. The stoichiometric relationship can be obtained directly by providing the stoichiometric content of the raw material, or indirectly by reacting part of the NCO by intentionally reacting the NCO with water or exposing it to external moisture.

Isocyanate-terminated prepolymer polyols include, for example, reaction products of polyols and polyfunctional aromatic isocyanates. Suitable polyols include, for example, polyether polyols; polycarbonate polyols; polyester polyols; polycaprolactone polyols; ethylene glycol; 1,2-propanediol; 1,3-propanediol; 1,2-butane Diol; 1,3-butanediol; 2-methyl-1,3-propanediol; 1,4-butanediol; neopentyl glycol; 1,5-pentanediol; 3-methyl-1, 5-pentanediol; 1,6-hexanediol; diethylene glycol; dipropylene glycol; tripropylene glycol, and mixtures thereof. Preferred polyols include polytetramethylene ether glycol [PTMEG]; polypropylene ether glycol [PPG]; ester-based polyols (such as ethylene adipate or butylene adipate); copolymers and mixtures. Examples of suitable polyfunctional aromatic isocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, benzidine Diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate and mixtures thereof. Preferably, the polyfunctional aromatic isocyanate comprises less than 20% by weight, preferably less than 15% by weight, most preferably less than 12% by weight of an aliphatic isocyanate such as 4,4'-dicyclohexylmethane diisocyanate; isophorone diisocyanate and cyclohexane diisocyanate. Preferably, the isocyanate-terminated prepolymer polyol comprises 8.75-9.40% by weight, preferably 8.90-9.30% by weight, more preferably 9.00-9.25% by weight of unreacted NCO moieties. Preferably, the isocyanate-terminated prepolymer polyol comprises isocyanate-terminated polytetramethylene ether glycol. More preferably, the isocyanate-terminated prepolymer polyol comprises isocyanate-terminated polytetramethylene ether glycol; wherein the isocyanate-terminated prepolymer polytetramethylene ether glycol comprises 8.90-9.30% by weight unreacted NCO fraction. Most preferably, said isocyanate-terminated prepolymer polyol comprises isocyanate-terminated polytetramethylene ether glycol; wherein said isocyanate-terminated prepolymer polytetramethylene ether glycol comprises 9.00-9.25% by weight unreacted NCO fraction.

Curing agents include, for example, 4,4'-methylene-di-o-chloroaniline [MBCA], 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline) (MCDEA); Dimethylthiotoluenediamine; 1,3-propylene glycol di-p-aminobenzoate; Polytetrahydrofuran di-p-aminobenzoate; Polytetrahydrofuran mono-p-aminobenzoate; Polypropylene oxide di-p-aminobenzoate Ester; Polypropylene oxide mono-p-aminobenzoate; 1,2-bis(2-aminophenylthio)ethane; 4,4'-methylene-diphenylamine; Diethyltoluenediamine; 5-tert-butyl-2,4-toluenediamine and 3-tert-butyl-2,6-toluenediamine; 5-tert-amyl-2,4-toluenediamine and 3-tert-amyl-2, 6-Toluenediamine and chlorotoluenediamine, and mixtures thereof. Preferably the curing agent is MBCA.

When making integral windows, the raw materials and stoichiometry are preferably selected such that the resulting integral window material has a compression set of 5-25%, more preferably 5-20%, even more preferably 5-15%, still more It is preferably 5-10%, more preferably 5% to less than 10%, most preferably 5-8%. The above compression set is measured under the conditions of 70°C and 22 hours according to ASTM D395-03 method A. Optionally, a separate compounding step can be used to make integral windows based on urethane polymers, avoiding the use of prepolymers.

The light transmittance of the integral window to light with a wavelength of 670 nm is preferably selected from the ranges of 20-70%, 20-50% and 30-50%.

The chemical mechanical polishing pad of the present invention optionally further includes a base layer adjacent to the polishing layer. An adhesive may optionally be used to attach the polishing layer to the base layer. The adhesive may be selected from pressure sensitive adhesives, hot melt adhesives, contact adhesives, and combinations thereof. In some embodiments, the adhesive is a hot melt adhesive. In some embodiments, the adhesive is a contact adhesive. In some embodiments, the adhesive is a pressure sensitive adhesive.

The chemical mechanical polishing pad of the present invention optionally further includes a base layer, and at least one additional layer adjacent to and interposed between the polishing layer and the base layer. Adhesives may optionally be used to join the layers together. The adhesive may be selected from pressure sensitive adhesives, hot melt adhesives, contact adhesives, and combinations thereof. In some embodiments, the adhesive is a hot melt adhesive. In some embodiments, the adhesive is a contact adhesive. In some embodiments, the adhesive is a pressure sensitive adhesive.

The chemical mechanical polishing pad of the present invention is preferably adapted to abut the platen of a polishing machine. Optionally, the chemical mechanical polishing pad of the present invention is secured to the platen using at least one of a pressure sensitive adhesive and a vacuum.

The polishing surface of the polishing layer of the chemical mechanical polishing pad of the present invention optionally has at least one of macrotexture and microtexture to facilitate polishing of the substrate. Preferably, the polishing surface has a macrostructure that serves to mitigate at least one of: slipping, affecting polishing media flow, altering the rigidity of the polishing layer, reducing edge effects, and facilitating transfer of polishing debris away from the polishing surface and the area between the substrate.

The polishing surface of the polishing layer of the chemical mechanical polishing pad of the present invention optionally has a macrostructure of at least one selected from perforations and grooves. Optionally, the perforations may extend partially or fully through the thickness of the polishing layer from the polishing surface. Optionally, the grooves are arranged on the polishing surface such that at least one of the grooves sweeps over the substrate as the polishing pad rotates during polishing. Optionally, the grooves are selected from curved grooves, straight grooves, and combinations thereof. Optionally, the grooves have a depth > 10 mils; preferably 10-150 mils. Optionally, the grooves form a groove pattern comprising at least two grooves having a combination of the following characteristics: a depth selected from > 10 mils, > 15 mils and 15-150 mils; a width Selected from ≥10 mils and 10-100 mils; slot pitch selected from ≥30 mils, ≥50 mils, 50-200 mils, 70-200 mils, and 90-200 mils.

The method for carrying out chemical mechanical polishing to a substrate selected from magnetic substrates, optical substrates and semiconductor substrates of the present invention includes: providing chemical mechanical polishing equipment, which includes a platen; The substrate and at least one of the semiconductor substrates; selecting a chemical mechanical polishing pad comprising a polishing layer comprising an integral window formed therein, the integral window having a compression set of 5-25% , preferably 5-20%, more preferably 5-15%, more preferably 5-10%, still more preferably 5-8%; the chemical mechanical polishing pad is installed on the platen; with the polishing layer The polishing surface polishes the at least one substrate. Preferably, after the polishing pad of the present invention polishes the substrate at a polishing temperature of 40° C. for 10 hours, the integral window in the chemical mechanical polishing pad protrudes ≤ 50 microns from the polishing surface of the polishing layer, more preferably 0-50 microns, most preferably 0-40 microns.

Some embodiments of the invention will now be described in detail in the following examples.

Example

window block

Window blocks were prepared by the following procedure for incorporation into chemical mechanical polishing layers as integral windows. Various amounts of curing agent (ie, MBCA) shown in Table 1 and isocyanate-terminated prepolymer polyol (ie, L325 from Chemtura) were mixed and added to the mold. The contents of the mold were then allowed to cure in an oven for 18 hours. The temperature of the oven was set at 93°C and heated for 20 minutes; then set at 104°C and heated for 15 hours and 40 minutes; then cooled to 21°C and treated for the last 2 hours. The window block is then cut into inserts for incorporation into a polishing pad cake by conventional means.

Table 1

Example MBCA (weight%) L325(weight%) stoichiometric ratio (NH ₂ /NCO) Window Comparative Example 1 18.4 81.6 0.78:1.00 Window Comparative Example 2 21.5 78.5 0.95:1.00 window 3 23.2 76.8 1.00:1.05

Compression Set Test

Samples of window blocks were prepared as described above and tested according to ASTM Method D395-03, Procedure A, to determine compression set. The results of these experiments are listed in Table 2.

Table 2

Example Measured Compression Set (inch %) Window comparative example 1-1 1.9 Window comparative example 1-2 2.0 Window comparative example 1-3 2.3 Window comparative example 2-1 4.6 Window comparative example 2-2 4.3 window 3-1 6.1 window 3-2 5.8 window 3-3 7.4

Polishing experiment

polishing pad

The following samples were prepared using the same polishing layer formulation: (a) a control polishing pad comprising the conventional monolithic window composition shown above in Window Comparative Example 1 of Table 1 with a stoichiometric ratio of _NH2 to NCO of 0.78:1.00, (b ) a polishing pad comprising the integral window composition of the present invention shown above in Example 3 of Table 1, wherein the stoichiometric ratio of _NH2 to NCO is 1:1.05. The control polishing pad with the conventional window formulation and the polishing pad including the inventive window formulation were both 50 mil thick with circular grooves 15 mil deep. Both polishing layer formulations were laminated on Suba IV ^™ subpad material available from Rohm and Haas Electronic Materials CMP Inc.

Polishing conditions

毫米抛光机和上文所述的抛光垫，在20.7千帕的抛光向下作用力条件下对铜覆盖晶片进行抛光；使用的化学机械抛光组合物为购自爱普客材料有限公司(Epoch Material Co.，Ltd)的EPL2361，流速为200毫升/分钟；台板转速93rpm；支架转速87rpm；使用Kinik

AD3CG 181060修整器，以48.3千帕的向下修整作用力进行完全的原位修整20分钟后中止，然后在62.1千帕的向下作用力下修整10分钟后中止，然后以48.3千帕的向下作用力进行修整。使用KLA TencorSP-1检验器具，在没有图案的晶片表面在0小时、2.5小时、5小时、7.5小时和10小时抛光后，测定铜覆盖晶片上的划痕数。这些划痕数检测结果列于表3。Using Applied Materials

Millimeter polisher and polishing pad as described above, under the condition of 20.7 kPa polishing downward force, copper clad wafer is polished; The chemical mechanical polishing composition used is purchased from Epoch Material Co., Ltd. ., Ltd) EPL2361, the flow rate is 200 ml/min;

AD3CG 181060 Dresser, full in-situ dressing at 48.3 kPa down force for 20 minutes, then aborted after 10 minutes at 62.1 kPa down force, then 48.3 kPa down force The lower force is used for trimming. Using a KLA Tencor SP-1 inspection tool, the number of scratches on copper coated wafers was measured after polishing the unpatterned wafer surface at 0 hours, 2.5 hours, 5 hours, 7.5 hours and 10 hours. The results of these scratch count tests are listed in Table 3.

table 3

window protruding

Additionally, after 10 hours of continuous wafer polishing under the described polishing conditions, the overall window profile was measured on the polished surface to determine the extent to which the window protrudes arbitrarily outwardly from the polished surface. The average protrusion of the overall window material of Comparative Example Window 1 is greater than 100 microns, while the average protrusion of the overall window material of Example Window 3 is less than 40 microns.

Claims (8)

1. a chemical mechanical polishing pads, it comprises:

Polishing layer, it comprises polished surface and integral window;

Described integral window becomes one in described polishing layer;

Described integral window is the polyurethane reaction product of curing agent and isocyanate-terminated prepolymer polyalcohol;

Described curing agent is selected from 4,4 '-methylene-bis-o-chloraniline, 4,4 '-methylene-bis--(3-chloro-2,6-diethyl aniline); Dimethythiotoluene diamine; Two p-aminobenzoic acid-1,3-PD ester; PolyTHF two p-aminobenzoic acid esters; PolyTHF list p-aminobenzoic acid ester; PPOX two p-aminobenzoic acid esters; PPOX list p-aminobenzoic acid ester; 1,2-bis-(2-aminobenzene-thio) ethane; 4,4 '-methylene-diphenylamines; Diethyl toluene diamine; The 5-tert-butyl group-2,4-toluenediamine; The 3-tert-butyl group-2,6-toluenediamine; 5-tertiary pentyl-2,4-toluenediamine; 3-tertiary pentyl-2,6-toluenediamine; Chlorotoluene diamines, and their mixture;

Described isocyanate-terminated prepolymer polyalcohol is the product of polyalcohol and multifunctional aromatic isocyanate;

Described polyalcohol is selected from polytetramethylene ether diol; Polytrimethylene ether glycol; Ester group polyol; Their copolymer and mixture;

Described multifunctional aromatic isocyanate is selected from 2,4-toluene di-isocyanate(TDI), 2,6-toluene di-isocyanate(TDI), 4,4'-methyl diphenylene diisocyanate, naphthalene-1,5-vulcabond, tolidine vulcabond, PPDI, XDI and their mixture;

Described curing agent comprises curing agent amine moiety, this curing agent amine moiety can with contained unreacted NCO partial reaction in described isocyanate-terminated prepolymer polyalcohol, form described integral window;

The consumption that amine moiety and the unreacted NCO stoichiometric proportion partly of take is 1:1 to 1:1.25 provides described curing agent and described isocyanate-terminated prepolymer polyalcohol;

The porosity <0.1 volume % of described integral window;

The compressive deformation of described integral window is 5-25%;

Wherein, described polished surface is applicable to for carrying out polishing to being selected from the substrate of magnetic substrate, optical base-substrate and semiconductor chip.

2. chemical mechanical polishing pads as claimed in claim 1, is characterized in that, described integral window has elliptic cross-section within being parallel to the plane of described polished surface.

3. chemical mechanical polishing pads as claimed in claim 1, is characterized in that, described isocyanate-terminated prepolymer polyalcohol comprises isocyanate-terminated polytetramethylene ether diol.

4. chemical mechanical polishing pads as claimed in claim 1, is characterized in that, the unreacted NCO part that described isocyanate-terminated prepolymer polyalcohol comprises 8.75-9.40 % by weight.

5. chemical mechanical polishing pads as claimed in claim 3, is characterized in that, the unreacted NCO part that described isocyanate-terminated polytetramethylene ether diol comprises 9.00-9.25 % by weight.

6. chemical mechanical polishing pads as claimed in claim 1, is characterized in that, described integral window is 20-50% at the light transmittance of 670 nanometers.

7. be used for a method of carrying out chemically mechanical polishing to being selected from the substrate of magnetic substrate, optical base-substrate and semiconductor chip, the method comprises:

Chemical-mechanical polisher is provided, and this equipment comprises platen;

At least one substrate being selected from magnetic substrate, optical base-substrate and semiconductor chip is provided;

Select chemical mechanical polishing pads as claimed in claim 1;

Described chemical mechanical polishing pads is arranged on described platen;

With the polished surface of described polishing layer, described at least one substrate carried out to polishing.

8. method as claimed in claim 7, is characterized in that, after substrate being carried out to the polishing of 10 hours, integral window from the polished surface of polishing layer outwardly≤50 microns.