KR20170072524A - Chemical Mechanical Polishing Slurry and POLISHING METHOD USING THE SAME - Google Patents

Abstract

A chemical mechanical polishing slurry composition of a tungsten containing a cyclic monosaccharide and a solvent as an abrasive, an oxidizing agent, an additive, and a solvent. The composition can reduce abrasion resistance and minimize tungsten defects while preserving polishing selectivity for tungsten.

Description

TECHNICAL FIELD The present invention relates to a chemical mechanical polishing slurry composition and a polishing method using the same,

The present invention relates to a chemical mechanical polishing slurry composition applicable to a semiconductor manufacturing process and the like, and a polishing method using the same.

An integrated circuit refers to a functional device having a complete circuit function, in which a plurality of active elements and passive elements are integrated in a single semiconductor substrate so that they can not be separated. In the structure of such a device, the intermediate connection structure is generally composed of various kinds of metal layers, intermediate connection layers, and insulating films. Interlayer dielectrics such as double doped and undoped silicon dioxide (SiO ₂ ) are used to electrically isolate a silicon substrate or various metal layers. A metal layer is also used to form an electrical connection between the intermediate connection layer and the device formed in the well. Typically, the metal path is filled with tungsten and an adhesion layer such as titanium nitride (TiN) or titanium is used to attach a metal layer, such as a tungsten metal layer, to the silicon dioxide. In one semiconductor manufacturing process, the metallized path is formed by performing a chemical mechanical polishing (CMP) step after the overall tungsten deposition. In the chemical mechanical polishing process, the substrate surrounds the contact substrate with the rotating polishing pad, and the carrier presses against the surface of the substrate. During the polishing process, the pressure is held against the substrate surface while the pad and table are rotated. A polishing solution, designated as a slurry, is adsorbed between the pad and the substrate during the polishing process. This slurry chemically acts on the polishing film to perform the polishing process. The polishing process is accomplished by rotational movement of the pad relative to the substrate as the slurry is fed to the wafer and pad interface. Polishing continues in this manner until the desired film on the substrate is removed.

A variety of compositions are added to the slurry, which is an important factor in the polishing process. Depending on the choice of oxidizing agent, abrasive and other useful additives, the polishing slurry may be adjusted to provide effective polishing and polishing selectivity in tungsten and various other films.

However, in the case of conventional tungsten CMP slurries, surface defects such as dishing and erosion are generated in the tungsten pattern. The defectivity of the tungsten CMP slurry increases as the pattern density increases, As the layering of the structure is increased, the influence is accumulated and the yield of semiconductor manufacturing is lowered.

Accordingly, there is a need for an improved slurry composition capable of minimizing defects such as erosion while maintaining the polishing selectivity and polishing rate for the tungsten film.

Patent Registration No. 10-1359092 (2014.01.28) Patent Registration No. 10-1325409 (Oct. 29, 2013)

The present invention provides a chemical mechanical polishing slurry composition and a polishing method for reducing erosion defects which are problematic while preserving polishing selectivity during tungsten pattern polishing.

As a technical means for achieving the above-mentioned technical object, a chemical mechanical polishing slurry composition of tungsten according to one aspect of the present invention includes a polishing agent, an oxidizing agent, a cyclic monosaccharide as a additive, and a solvent.

Here, the cyclic monosaccharide may be furanose or pyranose.

The cyclic monosaccharide may have 6 carbon atoms.

The cyclic monosaccharide may be one or more selected from D-mannose, D-fructose, D-alanus, D-tartose and D-glucose.

The composition may further comprise a pH adjusting agent, and the pH of the composition may be 3 to 4.

The composition may comprise 0.1 to 5% by weight of the abrasive, 0.1 to 5% by weight of the oxidizing agent, 0.01 to 5% by weight of a cyclic monosaccharide as the additive, and the remainder.

The slurry composition may be a barrier metal slurry capable of simultaneously polishing a tungsten film and a silicon oxide film.

A polishing method for polishing an abrasive article comprising a tungsten film and a silicon oxide film according to another aspect of the present invention includes the steps of using a slurry composition comprising colloidal silica as an abrasive, hydrogen peroxide as an oxidizing agent, a cyclic monosaccharide as an additive, A tungsten film, and a silicon oxide film.

The chemical mechanical polishing slurry composition of tungsten according to the present invention can reduce the amount of etching and minimize tungsten defects during wafer polishing, while preserving the polishing selectivity for tungsten.

Hereinafter, the present invention will be described in more detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

Chemical-mechanical polishing (CMP) is a type of surface planarization technique for semiconductor devices. Generally, the CMP process is performed by mechanical polishing with a polishing pad and chemical action of the slurry for CMP. At this time, the polishing efficiency of the CMP slurry may greatly affect the productivity of the semiconductor.

When the CMP slurry composition is applied to a semiconductor wafer, the polishing rate of each component contained in the semiconductor wafer may vary depending on the physical properties of each component, the kind of abrasive, the content and the kind of components contained in the slurry composition, and the like.

The present invention provides a chemical mechanical polishing slurry composition that can reduce defects in tungsten patterns while preserving polishing selectivity for tungsten.

The chemical mechanical polishing slurry composition of tungsten according to one aspect of the present invention comprises a polishing agent, an oxidizing agent, a cyclic monosaccharide as a additive, and a solvent.

The cyclic monosaccharide included as the additive may facilitate the polishing by promoting the oxidation of the metal layer by binding the hydroxy group in the monosaccharide with electrons. In addition, since the cyclic monosaccharide is capable of binding to and removing impurities such as abrasives after polishing, it contributes to prevention of defects on the surface of tungsten. Therefore, the slurry composition according to an embodiment of the present invention can reduce the amount of the irregularities in the polishing of the patterned wafer and minimize the tungsten defects while maintaining the polishing amount and the etching removing power for tungsten.

The cyclic monosaccharide may be furanose having a ring pentagonal shape or pyranose having a hexagonal ring, and preferably has 6 carbon atoms. Specifically, the cyclic monosaccharide may be at least one selected from D-mannose, D-fructose, D-alanus, D-tartose and D-glucose. The cyclic monosaccharide may be represented by the following formulas (1) to (5).

[Chemical Formula 1]

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

The content of the cyclic monosaccharide may be 0.01 to 5% by weight based on the total composition. When the content of the cyclic monosaccharide is less than 0.01% by weight, the effect of reducing the amount of irregularities and defects may be insignificant. When the content of the cyclic monosaccharide is more than 5% by weight, the polishing rate of tungsten is lowered, There may be a limit to the effect. Therefore, the content of the cyclic monosaccharide can be controlled within the above-mentioned range. More specifically, the content of the cyclic monosaccharide may be 0.05 to 3% by weight.

The abrasive is included for the purpose of polishing tungsten and a silicon oxide film, and conventional metal oxide particles can be used. Preferably it may be ceria (CeO _2), silica (SiO _2), alumina (Al ₂ O _3), zirconia (ZrO _2), titania (TiO _2), germania (GeO ₂₎ or a mixture thereof, more preferably Colloidal silica can be used.

The colloidal silica is also referred to as silica sol and means that solid silica particles are stably dispersed in a liquid such as water or an organic solvent without being precipitated or agglomerated do. The colloidal silica can be prepared by various methods such as dialysis, electrodialysis, peptization, acid-neutralization, and ion exchange. The colloidal silica is advantageous because the polishing rate of the silicon oxide film is higher than that of an abrasive such as fumed silica or alumina.

The particle size of the colloidal silica used as the abrasive is preferably 30 nm to 150 nm and is spherical. It is also possible to use only colloidal silica of the same size as the abrasive, or to mix colloidal silica of different sizes.

When the particle size of the abrasive is less than 30 nm, there is a possibility that the polishing efficiency of the substrate is lowered and the possibility of causing defects on the metal film quality is increased. If it is more than 150 nm, the dispersion stability of the slurry may be adversely affected, and the occurrence frequency of scratches may be increased. It also requires a large amount of abrasive material to achieve the polishing rate. Therefore, colloidal silica having an average particle diameter in the above-mentioned range can be used. More specifically, the average particle size of the colloidal silica may be 60 to 130 nm.

The content of the colloidal silica may be 0.1 to 5% by weight of the total polishing composition. When the content of the colloidal silica is too small, the polishing rate may be lowered. If the content of colloidal silica is too large, problems may arise in terms of dispersion stability. Therefore, the content of the colloidal silica can be controlled within the above-mentioned range. More specifically, the content of the colloidal silica may be 1 to 3% by weight.

The polishing selectivity of the tungsten film and the silicon oxide film can be controlled by controlling the average particle size and content of the colloidal silica.

The oxidizing agent may be included for the purpose of oxidizing the surface of the tungsten film to a brittle oxide which is easily polished by an abrasive.

The oxidizing agent may be an inorganic peroxide or an organic peroxide containing at least one peroxide bond (-OO-). The oxidizing agent is preferably selected from the group consisting of hydrogen peroxide, urea hydrogen peroxide, monopersulfate (SO ₅ ^2- ), dipersulfate (S ₂ O ₈ ^{2 -} ), peracetic acid, percarbonate, benzoyl peroxide, periodic acid, And may be at least one selected from perbromic acid, perboric acid, perborate, perchloric acid and perchlorate, peranganate and peranganate salts and mixtures thereof, and more preferably hydrogen peroxide.

The oxidizing agent may be included in an amount of 0.1 to 5.0% by weight based on the total weight of the slurry composition. If the amount of the oxidizing agent is less than 0.1% by weight, the oxidation reaction may not occur sufficiently and the polishing rate of the metal film may be slowed. If the oxidizing agent is more than 5% by weight, the possibility of defects on the tungsten surface is increased, There may arise a problem that it becomes difficult to adjust the polishing selection ratio of the silicon oxide. More specifically, the content of the hydrogen peroxide solution may be 0.1 to 3% by weight.

On the other hand, the oxidizing agent may not be added to the slurry production process, and it may be added to the slurry composition except for the oxidizing agent in the step of actually using the slurry in the polishing process.

The above-described slurry composition may further include a polishing adjuster or an abrasive accelerator to adjust the polishing rate of the tungsten film.

As the polishing regulator, a compound having an amine group may be used. Specifically, at least one selected from amino acids or amino alcohols may be used. More specifically, the aminoalcohol is selected from the group consisting of 2-amino-2-methyl-1-propanol, 3-amino- At least one selected from 2- (2-aminoethylamino) ethanol, 2-dimethylamino-2-methyl-1-propanol, N, N-diethylethanolamine, monoethanolamine, diethanolamine and triethanolamine And examples of the amino acid include at least one selected from arginine, cysteine, aspartic acid, glutamic acid, glycine, histidine, phenylalanine, serine, valine, methionine, asparagine, lysine and alanine. The content of the abrasive modifier may be 0.01 to 10% by weight based on the total composition. If the content of the abrasive modifier is too small, the effect of addition may be insignificant. If the content of the abrasive modifier is too large, the dispersibility may be deteriorated. Therefore, an abrasive modifier can be added to the above-mentioned range. More specifically, the content of the abrasive modifier may be 1 to 7% by weight.

As the polishing accelerator, at least one selected from phosphoric acid, phosphorous acid, organic phosphoric acid and organic phosphorous acid can be used. In the case of phosphorous acid and organic phosphorous acid, it is particularly useful for promoting the polishing of a titanium-based film. Organic phosphonic acids include 2-aminoethylphosphonic acid, amino (trimethylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), hexamethylenediamine tetra (methylenephosphonic acid), or ethylenediaminetetra (Methylenephosphonic acid) (EDTMP), nitrilotris (methylene) triphosphonic acid (NTPA), and the like. The content of the polishing accelerator may be 0.01 to 10% by weight based on the total composition. When the content of the polishing accelerator is too small, a problem that the increase of the polishing rate is insignificant may occur. If the content of the abrasive accelerator is too high, corrosion of the tungsten film may be caused. Therefore, an abrasive accelerator can be added in the above-mentioned range. More specifically, the content of the polishing accelerator may be 1 to 3% by weight.

The above-described slurry composition may further comprise a pH adjusting agent to adjust the pH of the composition.

As the pH adjusting agent, at least one of sulfuric acid, hydrochloric acid, nitric acid, carbonic acid and acetic acid may be used as the acid, and at least one of potassium hydroxide, sodium hydroxide and ammonia may be used as a base. The pH of the composition can be adjusted to 3 to 4 using a pH adjusting agent. If the pH is too low, corrosion may occur on the surface of the tungsten film. If the pH is too high, the dispersion stability of the colloidal silica particles may deteriorate and the polishing rate of the tungsten film may be lowered. Thus, the pH can be adjusted to the above-mentioned range.

The solvent is not particularly limited as long as it is capable of easily dispersing the composition of the above-mentioned composition. Specifically, it may be at least one selected from water, methanol, ethanol, isopropanol and propylene glycol. When water is used as a solvent, it is preferable to use deionized water (DIW).

The chemical mechanical polishing slurry composition of tungsten according to one aspect of the present invention may be a barrier metal slurry capable of simultaneously polishing a tungsten film and a silicon oxide film.

In the chemical mechanical polishing process, most of the metal film is removed by using a primary polishing slurry (bulk slurry) having a high polishing amount for the metal film, and a plurality of films such as a metal wiring portion and an interlayer insulating film are simultaneously polished more finely A secondary polishing slurry (barrier metal slurry) can be used.

Chemical mechanical polishing of tungsten The bulk slurry includes an oxidizing agent and an iron catalyst in order to mainly polish tungsten, but it is preferable that the barrier metal slurry contains a small amount of an oxidizing agent and does not contain an iron catalyst. Further, it is preferable that the barrier metal slurry has a small difference in polishing rate between the tungsten film and the insulating film, and should be able to improve the surface defects generated in the primary polishing.

By performing secondary polishing using the barrier metal slurry according to an embodiment of the present invention, it is possible to eliminate the occurrence of dissociation and dishing occurring in the primary polishing step of tungsten.

According to an embodiment of the present invention, it is possible to minimize surface impurities such as metal particles and abrasive grains that remain as an effect of adding the monosaccharide described above. This may be the effect of multiple hydroxyl groups on the cyclic monosaccharide. Removal of such impurities may have an effect on reducing defects such as erosion of the polished film.

Meanwhile, the slurry composition according to an embodiment of the present invention can reduce defects in dishing and erosion that occur in a chemical mechanical polishing process, and in particular, can reduce edge over erosion (EOE) .

Dishing is a defect occurring only in one wiring at a wide width of metal wiring, and erosion is a defect occurring over various wiring in a region where pattern density of metal wiring is high. Edge over Erosion is a kind of erosion, which means erosion that occurs at high density areas of metal wiring and low area boundary.

According to another aspect of the present invention, there is provided a polishing method for polishing an object to be polished by using a slurry composition comprising colloidal silica as an abrasive, hydrogen peroxide as an oxidizing agent, a cyclic monosaccharide as an additive, and a solvent. Since the description of the slurry composition is the same as that described above, repeated description is omitted.

The object to be polished may include a tungsten film and a silicon oxide film, and may specifically include a tungsten film, a titanium-based film, and a silicon oxide film. More specifically, the titanium-based film may be made of titanium or titanium nitride.

The above polishing method is performed by performing primary polishing with a primary slurry (bulk slurry) containing an oxidizing agent and an iron catalyst, and then performing secondary polishing with a barrier metal slurry according to an embodiment of the present invention described above .

The barrier metal slurry may be first prepared in a composition excluding the oxidizing agent, and then polished by adding an oxidizing agent in the secondary polishing step.

The polishing method can reduce defects in the tungsten pattern being polished while preserving the polishing selectivity of the slurry.

On the other hand, in the present specification, it is to be noted that, when a component includes any component, it does not exclude other components, but may include other components, It will be appreciated that a variety of additional components may be included in the composition depending on the purpose and conditions in which the chemical mechanical polishing slurry composition described above is used.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Example  One

2% by weight of colloidal silica (average particle diameter of about 40 nm) as an abrasive, 1% by weight of hydrogen peroxide as an oxidizing agent, and 0.2% by weight of D-mannose as an additive were deionized water and pH was adjusted to 3 One slurry composition was prepared with a total weight of 1 kg.

Example  2

Fructose was prepared in the same manner as in Example 1, except that D-fructose was used as an additive.

Example  3

The procedure of Example 1 was repeated except that D-Alnose was used as an additive.

Example  4

The procedure of Example 1 was repeated except that D-maltose was used as an additive.

Example  5

The procedure of Example 1 was repeated except that D-glucose was used as an additive.

Comparative Example  One

A cyclic monosaccharide additive was prepared in the same manner as in Example 1 except that the cyclic monosaccharide additive was not used.

Experimental Example  1: Polishing rate and etching Removal power

Polishing equipment was POLI-400 equipment, and polishing pad was used for IC (Polishing equipment). Polishing equipment was PETEOS (Plasma Enhanced Tetra Ethyle Ortho Silicate) wafer (thickness 20000 Å) and W (tungsten) The polishing rate was 3.5 psi and the table / head speed was adjusted to 101/100 rpm. The feed rate was 100 ml and the polishing time was 60 seconds. Respectively.

Thickness of PETEOS wafers was measured with SpectraTick ST5000 (Spectra Thick ST5000 K-MAC), and thickness of wafers was measured with a 4-probe surface resistance meter. The surface of the pattern was measured with a profiler of XP-300 (AMBIOS), and the results are shown in Table 1 below. The etching removal force was evaluated at 65 ° C for 3 minutes, and the results are shown in Table 1 below.

PETEOS (OXIDE) Polishing speed (Å / min) W polishing rate
(Å / min) Selective burnout
(PETEOS (OXIDE) polishing speed / W polishing speed) Etching removal power
(Å / min) Example 1 822 233 3.5 83 Example 2 784 65 12.1 75 Example 3 806 131 6.2 93 Example 4 808 127 6.4 98 Example 5 805 123 6.5 99 Comparative Example 1 818 144 5.7 94

As shown in Table 1, it can be confirmed that the polishing rate and the etching removal power of Examples 1 to 6 are equivalent to those of Comparative Example 1.

Experimental Example  2: Erosion removal effect

Under the same conditions as in Experimental Example 1 described above, the effect of erosion removal by six patterns was confirmed using a wafer of SKW Company. The results are shown in Table 2 below.

Pattern 1 Pattern 2 Pattern 3 Pattern 4 Pattern 5 Pattern 6 Trench width (탆) 0.12 0.12 0.14 0.14 0.25 0.25 SiO ₂ Width (탆) 0.22 0.12 0.26 0.14 0.46 0.25 density 35% 50% 35% 50% 35% 50% Erosion (Å) Example 1 99 93 94 98 98 75 Example 2 56 46 84 45 24 54 Example 3 17 25 62 34 27 58 Example 4 34 26 21 34 24 62 Example 5 42 37 23 67 23 56 Comparative Example 1 150 156 122 173 164 153

As shown in Table 2, it can be seen that Examples 1 to 6 containing the cyclic monosaccharide additive showed less erosion than Comparative Example 1.

Experimental Example  3: Residual amount of abrasive

The composition of Example 3 and Comparative Example 1, in which the erosion removal effect was the best, was cleaned once to three times after the polishing evaluation. After the cleaning, the abrasive remaining amount in the size of 0.2 탆 and 0.13 탆 was measured and shown in Tables 3 and 4 below. The residual amount means the number of remaining particles on the whole wafer of 200 mm size.

(Unit: number) 0.2 탆 1 time cleaning 2 times cumulative cleaning 3 times cumulative cleaning Example 3 241 354 368 Comparative Example 1 345 567 733

(Unit: number) 0.13 탆 1 time cleaning 2 times cumulative cleaning 3 times cumulative cleaning Example 3 321 355 401 Comparative Example 1 457 670 799

As shown in Tables 3 and 4, when the cyclic monosaccharide additive is included, it can be confirmed that the amount of the abrasive remaining after the chemical mechanical polishing process is reduced.

As described above, according to the embodiment of the present invention, it is possible to reduce the amount of etching and reduce defects in the wafer, while maintaining a similar polishing amount and etching removal force when using the same abrasive, It can be confirmed that the tungsten barrier polishing composition improved from the existing product.

Referring to Table 2 above, Example 3 contains 10-90% of the substrate compared to Comparative Example 1, with a substrate having a 0.12 micrometer trench divided by a silicon dioxide 0.12 micrometer region and having a 35% and 50% pattern density, Erosion is reduced. These results can prove that the erosion of the tungsten-containing layer can be substantially reduced by the use of the polishing composition according to Embodiment 3 of the present invention. From the above data, it can be confirmed that the cyclic saccharides (alcohol saccharides), among the additives, contribute to erosion and prevention of defects.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

Claims (8)

Abrasives,
Oxidant,
The cyclic monosaccharide and /
A chemical mechanical polishing slurry composition of tungsten comprising a solvent. The method according to claim 1,
Wherein the cyclic monosaccharide is furanos or pyranose. ≪ RTI ID = 0.0 > 8. < / RTI > The method according to claim 1,
Wherein the cyclic monosaccharide has a carbon number of 6. The chemical mechanical polishing slurry composition of claim 1, The method according to claim 1,
Wherein the cyclic monosaccharide is at least one selected from D-mannose, D-fructose, D-alanus, D-maltose and D-glucose. The method according to claim 1,
The composition further comprises a pH adjusting agent,
A chemical mechanical polishing slurry composition of tungsten wherein the composition has a pH of from 3 to 4. The method according to claim 1,
0.1 to 5% by weight of the abrasive,
0.1 to 5% by weight of the oxidizing agent,
0.01 to 5% by weight of a cyclic monosaccharide as the additive and
Solvent
≪ / RTI > wherein the chemical mechanical polishing slurry composition comprises tungsten. The method according to claim 1,
Wherein the slurry composition is a barrier metal slurry capable of simultaneously polishing a tungsten film and a silicon oxide film. A polishing method for polishing an object to be polished comprising a tungsten film and a silicon oxide film by using a slurry composition comprising colloidal silica as an abrasive, hydrogen peroxide as an oxidizing agent, a cyclic monosaccharide as an additive, and a solvent.