KR20180069773A - Chemical mechanical polishing slurry composition - Google Patents

Abstract

Disclosed is a chemical mechanical polishing (CMP) slurry composition which is capable of remarkably improving polarization ratio when performing a CMP process for a semiconductor interlayer dielectric (ILD) film. The CMP slurry composition comprises: abrasive particles; a pH adjusting agent; a pH buffing agent; water; and an ionic liquid represented by chemical formula 1. In chemical formula 1, R_1 and R_2 are each independently a C_1-C_10 alkyl group, and X^- indicates a monovalent anion.

Description

[0001] Chemical-mechanical polishing slurry composition [0002]

The present invention relates to a chemical-mechanical polishing slurry composition, and more particularly, to a chemical-mechanical polishing slurry composition capable of remarkably improving a planarization rate when a chemical mechanical polishing (CMP) process for an interlayer dielectric (ILD) To a chemical-mechanical polishing slurry composition.

A chemical mechanical polishing (CMP) process for planarizing an insulating film is typically performed during the manufacture of semiconductor devices. Particularly, the chemical-mechanical polishing process for interlayer dielectric (ILD) of a semiconductor has a higher polishing speed than that of the lower portion (recess) of the pattern, which is the etch stop film in a single film having a height step, (Planarization). However, when a general polishing slurry is used for polishing, there is a problem in that the difference in polishing rate between the pattern and the lower portion is not large, and the step remains even after polishing.

As a conventional technique for solving such a problem, Patent Application No. 10-2005-0127065 discloses an aqueous slurry for chemical mechanical polishing using a relatively long amine-based additive having an alkyl chain. In Patent Document 10-2004-0016154, A chemical mechanical polishing slurry comprising oxide abrasive grains, a removal rate accelerator, and an anionic polymer passivating agent is disclosed, and Patent Application 10-2006-0117367 discloses a polishing slurry composition comprising a gemini surfactant .

However, even if the method of the above patent is used, there is a fear that the steps are not easily removed in a dense region or the upper structure formed on the semiconductor substrate is damaged due to no abrasive termination characteristic. In general chemical- Use may be limited since a longer polishing time is required.

Accordingly, an object of the present invention is to provide a chemical-mechanical polishing slurry composition having an excellent planarization ratio when a chemical mechanical polishing (CMP) process for an interlayer dielectric (ILD) is performed.

In order to achieve the above object, pH adjusting agents; pH buffering agents; water; And a chemical-mechanical polishing slurry composition comprising an ionic liquid represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, R ₁ and R ₂ are each independently an alkyl group having 1 to 10 carbon atoms, and X ^- represents a monovalent anion.

The chemical-mechanical polishing slurry composition according to the present invention includes an ionic liquid having an imidazole structure. When the chemical mechanical polishing (CMP) process for an interlayer dielectric (ILD) The ionic liquid is adsorbed on the recesses (lower portion of the pattern) of the interlayer insulating film having a relatively low polishing pressure to form a protective layer. Therefore, the polishing rate of the concave portion (lower portion of the pattern) of the interlayer insulating film can be significantly lowered compared with the polishing rate of the interlayer insulating film convex portion (upper portion of the pattern), and the planarization of the interlayer insulating film having a step difference can be achieved.

Hereinafter, the present invention will be described in detail.

The chemical-mechanical polishing slurry composition according to the present invention is used for performing a chemical mechanical polishing (CMP) process for a semiconductor interlayer dielectric (ILD), and includes abrasive particles, a pH adjuster, a pH buffer, And ionic liquids.

The ionic liquid used in the present invention is represented by the following formula (1), and the imidazolium cation of the ionic liquid is adsorbed on the wafer (particularly, the concave portion (pattern lower portion) of the interlayer insulating film) (Particularly, the recessed portion (lower portion of the pattern) of the interlayer insulating film).

등을 나타낸다.R ₁ and R ₂ are each independently an alkyl group having 1 to 10 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group or a pentyl group, X ^- is a monovalent anion, _{^{Cl -, Br -, BF 4}} -, PF 6 -, (CF 3 SO 2) 2 N - (trifluoromethylsulfonylamide anion: Tf 2 N -), CF 3 SO 2 - (trifluoromethylsulfonate anion: TfO -), CF 3 COO - ^{_{, (CN) 2 N -,}} SCN -, FeCl 4 -, (CH 3 O) 2 PO 2 -, NO 3 -, HSO 4 -,

And so on.

Non-limiting examples of the ionic liquid represented by the formula (1) include ionic liquids represented by the following formulas (1a) to (1u).

[Formula 1a]

[Chemical Formula 1b]

*

[Chemical Formula 1c]

≪ RTI ID = 0.0 &

[Formula 1e]

(1f)

[Formula 1g]

[Chemical Formula 1h]

[Formula 1i]

[Chemical Formula 1j]

[Chemical Formula 1k]

≪ EMI ID =

[Formula 1m]

[Formula 1n]

≪ EMI ID =

[Chemical Formula 1p]

[Chemical Formula 1q]

[Chemical Formula 1 r]

[Formula 1s]

[Formula 1t]

[Formula 1]

The content of the ionic liquid is 0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.1 to 3% by weight, based on the total chemical mechanical polishing slurry composition. If the content of the ionic liquid is less than 0.01% by weight, the protective layer may not be formed due to the inability to be adsorbed on the concave portion (lower portion of the pattern) of the interlayer insulating film. If the content exceeds 10% by weight, ), The protective layer is formed over the entire wafer, and the polishing may not proceed.

The abrasive grains used in the present invention perform mechanical polishing of a semiconductor interlayer dielectric (ILD), and can use abrasive grains (abrasives) used in conventional chemical-mechanical polishing slurry compositions without limitation, For example, colloidal silica, fumed silica, alumina, ceria, titania, zirconia, zenonia, etc. may be used alone or in combination. Preferably, ceria can be used and mixed with other additives in the form of a slurry dispersed in water such as ultrapure water and incorporated into the chemical-mechanical polishing slurry composition of the present invention. The content of the abrasive grains is 0.1 to 10% by weight, preferably 0.2 to 7% by weight, more preferably 0.2 to 5% by weight based on the total chemical-mechanical polishing slurry composition. When the content of the abrasive grains is less than 0.1 wt%, the convex portion (pattern upper portion) of the interlayer insulating film at the time of polishing is not sufficiently polished, and the polishing selectivity ratio of the convex portion and the concave portion of the interlayer insulating film is lowered, On the other hand, when the amount exceeds the above range, scratches such as scratches on the surface of the interlayer insulating film may be caused. In addition, the size of the abrasive grains is not particularly limited, but preferably has a particle size of, for example, 50 to 300 nm.

The pH adjusting agent used in the present invention is to adjust the pH of the chemical-mechanical polishing slurry composition to 4 to 10, preferably 5 to 8, more preferably 5.5 to 7, Examples of the pH adjuster (acid, base, etc.) used may include, but are not limited to, phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, ammonia, potassium hydroxide, tetramethylammonium hydroxide (TMAH) Tetraethylammonium hydroxide (TEAH), tetrabutylammonium hydroxide (TBAH), etc. may be used alone or in combination.

If the pH of the chemical-mechanical polishing slurry composition is out of the above-mentioned range, the dispersibility of the abrasive grains is deteriorated, and there is a fear that the abrasion can not occur sufficiently during the polishing step. The content of the pH adjusting agent may vary depending on the pH of the chemical-mechanical polishing slurry composition, but may be, for example, 0.05 to 10% by weight, preferably 0.1 to 5% by weight %, More preferably 0.3 to 2% by weight. If the content of the pH adjusting agent is out of the above range, the pH of the chemical-mechanical polishing slurry composition becomes difficult to control and may act as an impurity.

The pH buffer used in the present invention is used for preventing abrupt changes in pH occurring when a solution (slurry) in which abrasive grains are dispersed and an additive such as an ionic liquid and a pH adjuster are mixed, For example, a water-soluble polymer used also as a dispersing agent for abrasive particles, preferably a polymer of an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, an ammonium salt thereof, an amine salt thereof, acrylic acid, methacrylic acid, Unsaturated carboxylic acids such as maleic acid, and alkyl acrylates such as methyl acrylate and ethyl acrylate, hydroxyalkyl acrylates such as hydroxyethyl acrylate, alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, hydroxyethyl methacrylate , A copolymer of a copolymerizable monomer such as hydroxyalkyl methacrylate, vinyl acetate or vinyl alcohol, an ammonium salt thereof or Amine salts, mixtures thereof and the like can be used. Non-limiting examples of the water-soluble polymer such as the above polymer and copolymer include polyacrylic acid, polyacrylic maleic acid copolymer, polyacrylic methacrylic acid polymer, polyacrylamide, and polyacrylic acid ammonium salt.

The content of the pH buffer is 0.05 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.2 to 2% by weight based on the total chemical mechanical polishing slurry composition. If the content of the abrasive grains is less than 0.05% by weight, it may fail to serve as a pH buffering agent. If the content of the abrasive grains exceeds 10% by weight, the dispersibility of the abrasive grains may deteriorate and cause defects such as scratches on the surface of the interlayer insulating film. There is a concern. When the pH buffer is a water-soluble polymer, the weight-average molecular weight of the water-soluble polymer is 1,000 to 100,000, preferably 3,000 to 20,000, although it is not particularly limited. If the weight average molecular weight of the water-soluble polymer (pH buffer) is less than 1,000, it may fail to serve as a pH buffer. If the weight average molecular weight exceeds 100,000, the dispersibility of the abrasive particles may deteriorate.

The remaining components of the chemical-mechanical polishing slurry composition according to the present invention are water, preferably distilled water, deionized water, ultrapure water, and more preferably ultrapure water.

The polishing slurry composition according to the present invention may further contain conventional additives such as a dispersant for maintaining dispersion stability and various salts for lowering the viscosity of the dispersion liquid, if necessary.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples illustrate the present invention and are not intended to limit the scope of the present invention.

[Preparation Example] Preparation of ceria-containing slurry

23 kg of a water-soluble polyacrylic acid solution (40% by weight) as a pH buffering agent (dispersant) and 8,977 g of ultra pure water were mixed as abrasive grains, followed by ultrasonic dispersion for 10 minutes while stirring. The obtained slurry was filtered with a 1-micron filter, and ultrapure water was further added to obtain a ceria-containing slurry having a ceria content of 5% by weight. The slurry was diluted to an appropriate concentration and the particle size was measured using a laser scattering type particle size distribution meter (trade name: Master Sizer Microplus, manufactured by Malvern). The average particle size was 200 nm.

[Example 1] Preparation and evaluation of chemical-mechanical polishing slurry composition

2% by weight of polyacrylic acid (pH buffer) having a weight average molecular weight (Mw) of 10,000, 2% by weight of tetramethylammonium hydroxide (TMAH, pH adjusting agent) and 1% by weight of an ionic liquid (1-methyl- 3-butyl-imidazolium Chloride) was added to ultrapure water to prepare an additive. The ceria-containing slurry prepared in the above Preparation Example and the additive were mixed so as to have a ratio of 1:10, thereby preparing a chemical-mechanical polishing slurry composition .

Then, the above-described chemical-mechanical polishing slurry composition and polishing apparatus (equipment name: Mirra, manufacturer: AMAT), polishing pad (IC1000 / suba IV, Rohm & The polishing of the pattern wafer was performed under the conditions of a head rotational speed of 87 rpm, a platen rotational speed of 93 rpm, a wafer pressure of 4.0 psi, and a slurry composition flow rate of 200 ml / min. The thickness of the patterned wafer before and after polishing of the patterned wafer was measured using a thickness measuring device (Nanospec 2000, manufacturer: Nanometrics) to calculate the recessed portion polishing rate, the polishing rate of the recessed portion, and the selectivity of the recessed portion and the recessed portion, The results are shown in Table 1 below.

[Example 2] Preparation and evaluation of chemical-mechanical polishing slurry composition

Mechanical polishing slurry composition was prepared in the same manner as in Example 1 except that 1.0 wt% was used instead of 0.5 wt% of the ionic liquid (1-methyl-3-butyl-imidazolium chloride) Were prepared and evaluated. The results are shown in Table 1 below.

[Example 3] Preparation and evaluation of chemical-mechanical polishing slurry composition

0.5% by weight of an ionic liquid (1-ethyl-3-butyl-imidazolium chloride) represented by the above formula (1s) was used instead of 0.5% by weight of the ionic liquid (1-methyl- Was used to prepare and evaluate a chemical-mechanical polishing slurry composition in the same manner as in Example 1, and the results are shown in Table 1 below.

[Example 4] Preparation and evaluation of chemical-mechanical polishing slurry composition

0.5% by weight of 1-ethyl-3-methyl-imidazolium chloride represented by the formula 1n was used instead of 0.5% by weight of the ionic liquid (1-methyl-3-butyl-imidazolium chloride) Was used to prepare and evaluate a chemical-mechanical polishing slurry composition in the same manner as in Example 1, and the results are shown in Table 1 below.

[Example 5] Preparation and evaluation of chemical-mechanical polishing slurry composition

1.0% by weight of an ionic liquid (1-ethyl-3-methyl-imidazolium chloride) represented by the formula 1n was used instead of 0.5% by weight of the ionic liquid (1-methyl- Was used to prepare and evaluate a chemical-mechanical polishing slurry composition in the same manner as in Example 1, and the results are shown in Table 1 below.

[Example 6] Preparation and evaluation of chemical-mechanical polishing slurry composition

3.0 wt% of 1-ethyl-3-methyl-imidazolium chloride represented by the above formula (1n) was used instead of 0.5 wt% of the ionic liquid (1-methyl-3-butyl- imidazolium chloride) Was used to prepare and evaluate a chemical-mechanical polishing slurry composition in the same manner as in Example 1, and the results are shown in Table 1 below.

[Example 7] Preparation and evaluation of chemical-mechanical polishing slurry composition

5.0 wt% of the ionic liquid (1-ethyl-3-methyl-imidazolium chloride) represented by the above formula (1n) was used instead of 0.5 wt% of the ionic liquid represented by the formula (1r) Was used to prepare and evaluate a chemical-mechanical polishing slurry composition in the same manner as in Example 1, and the results are shown in Table 1 below.

[Example 8] Preparation and evaluation of chemical-mechanical polishing slurry composition

0.5 wt% of an ionic liquid (1-methyl-3-butyl-imidazolium tetrafluoroborate) represented by the formula (1t) was used instead of 0.5 wt% of the ionic liquid represented by the formula (1r) Was used to prepare and evaluate a chemical-mechanical polishing slurry composition in the same manner as in Example 1, and the results are shown in Table 1 below.

[Example 9] Preparation and evaluation of chemical-mechanical polishing slurry composition

0.5 wt% of the ionic liquid (1-methyl-3-octyl-imidazolium tetrafluoroborate) represented by the above formula (1u) was used instead of 0.5 wt% of the ionic liquid represented by the formula (1r) Was used to prepare and evaluate a chemical-mechanical polishing slurry composition in the same manner as in Example 1, and the results are shown in Table 1 below.

[Comparative Example] Preparation and evaluation of chemical-mechanical polishing slurry composition

A chemical-mechanical polishing slurry composition was prepared and evaluated in the same manner as in Example 1, except that the ionic liquid was not used, and the results are shown in Table 1 below.

Ionic liquid content waist
Polishing rate
(Å / min) Convex
Polishing rate
(Å / min) Yo
Selection ratio
(Iron / lumbar) Example 1 1-methyl-3-butyl-imidazolium chloride 0.5 wt% 2525 151 16.7 Example 2 1-methyl-3-butyl-imidazolium chloride 1.0 wt% 2037 50 40.7 Example 3 1-ethyl-3-butyl-imidazolium chloride 0.5 wt% 2321 132 17.6 Example 4 1-ethyl-3-methyl-imidazolium chloride 0.5 wt% 3052 130 23.5 Example 5 1-ethyl-3-methyl-imidazolium chloride 0.1 wt% 3325 171 19.4 Example 6 1-ethyl-3-methyl-imidazolium chloride 3.0wt% 1511 81 18.7 Example 7 1-ethyl-3-methyl-imidazolium chloride 5.0 wt% 651 77 8.5 Example 8 1-methyl-3-butyl-imidazolium tetrafluoroborate 0.5 wt% 2112 98 21.6 Example 9 1-methyl-3-octyl-imidazolium tetrafluoroborate 0.5 wt% 1822 43 42.4 Comparative Example - - 1515 522 2.9

It can be seen from the above results that the chemical mechanical polishing slurry composition (embodiment) according to the present invention can be used in a chemical mechanical polishing (CMP) process for a semiconductor interlayer dielectric (ILD) The polishing rate of the concave portion (lower portion of the pattern) of the interlayer insulating film can be remarkably lowered (polishing selectivity ratio (recessed portion / convex portion): 8.5 or more) compared with the polishing rate of the interlayer insulating film. .

Claims (8)

0.2 to 5 wt% abrasive particles;
pH adjusting agents;
pH buffering agents;
water; And
A chemical-mechanical polishing slurry composition comprising an ionic liquid represented by the following formula (1).
[Chemical Formula 1]

In Formula 1, R ₁ and R ₂ are each independently an alkyl group having 1 to 10 carbon atoms, and X ^- represents a monovalent anion. 2. The method of claim 1, wherein X ^- is _{^{Cl -, Br -, BF 4}} -, PF 6 -, CF 3 SO 2) 2 N -, CF 3 SO 2 -, CF 3 COO -, (CN) 2 N - , SCN ^- , FeCl ₄ ^- , (CH ₃ O) ₂ PO ₂ ^- , NO ₃ ^- , HSO ₄ ^- and

Lt; RTI ID = 0.0 > 1, < / RTI > The chemical-mechanical polishing slurry composition according to claim 1, wherein the ionic liquid represented by Formula 1 is selected from the group consisting of ionic liquids represented by the following Chemical Formulas 1a to 1u.
[Formula 1a]

[Chemical Formula 1b]

[Chemical Formula 1c]

≪ RTI ID = 0.0 &

[Formula 1e]

(1f)

[Formula 1g]

[Chemical Formula 1h]

[Formula 1i]

[Chemical Formula 1j]

[Chemical Formula 1k]

≪ EMI ID =

[Formula 1m]

[Formula 1n]

≪ EMI ID =

[Chemical Formula 1p]

[Chemical Formula 1q]

[Chemical Formula 1 r]

[Formula 1s]

[Formula 1t]

[Formula 1]

The polishing slurry composition of claim 1, wherein the pH adjuster is 0.05 to 10 wt%, the pH buffer is 0.05 to 10 wt%, the ionic liquid is 0.01 By weight to 10% by weight, and the balance being water. The chemical-mechanical polishing slurry composition of claim 1, wherein the abrasive particles are selected from the group consisting of colloidal silica, fumed silica, alumina, ceria, titania, zirconia, zenonia, and mixtures thereof. The method of claim 1, wherein the pH adjusting agent is selected from the group consisting of phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, ammonia, potassium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, ≪ / RTI > The pH buffer according to claim 1, wherein the pH buffer is selected from the group consisting of a polymer of an unsaturated carboxylic acid, an ammonium salt or amine salt thereof, a copolymer of an unsaturated carboxylic acid monomer and a copolymerizable monomer, an ammonium salt or an amine salt thereof, Wherein the water-soluble polymer is a water-soluble polymer selected from the group consisting of water-soluble polymers. The chemical-mechanical polishing slurry composition of claim 1, wherein the water is distilled water, deionized water, or ultrapure water.