KR20040040810A - CMP Slurry for Polishing of Cu Lines - Google Patents

Abstract

PURPOSE: A CMP(Chemical Mechanical Polishing) slurry for polishing a copper line is provided to be capable of protecting a porous layer formed at the surface of an oxidized copper line for preventing additional oxidation and conserving a high polishing speed. CONSTITUTION: A CMP slurry for polishing a copper line contains metal oxide micro powder, peroxide compound, benzene based compound, ammonium salt or amine based compound, carboxyl based compound, and deionized water. Preferably, the CMP slurry is made of the metal oxide micro powder of 1-15 weight%, the peroxide compound of 0.1-10 weight%, the benzene based compound of 0.01-0.5 weight%, the ammonium salt or amine based compound of 0.01-0.5 weight%, the carboxyl based compound of 0.001-0.5 weight% and the deionized water.

Description

CMP Slurry for Polishing of Cu Lines

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing slurry applied to a chemical mechanical polishing (CMP) process in the manufacture of a semiconductor device. It relates to the target CMP slurry.

The CMP process refers to a process of flattening a wafer surface by adding an slurry containing an abrasive to a semiconductor wafer surface during semiconductor manufacturing and then performing an orbital motion mixed with rotation and linear motion in contact with a polishing pad. The components of the slurry used in the CMP process are largely divided into abrasive particles, which are physically active, and compounds such as etchant, which are chemically active. Thus, the CMP process makes it possible to selectively etch exposed portions of the wafer surface by physical and chemical action to achieve more optimized and broader planarization.

In general, in the semiconductor process, the CMP process is widely used as a process for forming metal interconnections and plugs or vias of a highly integrated circuit. In such a process, a low dielectric film such as SOG or BPSG, O3-TEOS, USG, P-TEOS, LOW-K, FOX, etc. is first deposited on a wafer or a metal layer, and then photolithography is performed.

After forming a trench in the low dielectric film through a photolithography process and a dry etch process, titanium and titanium nitride are used to improve adhesion between the metal layer and the low dielectric film. A barrier layer of nitride, tantalum, tantalum nitride, or the like is deposited. Next, metal wires or plugs are deposited with a conductive material such as tungsten or aluminum, or copper or a copper alloy. Finally, in the CMP process using the slurry for metal polishing, all metal layers on the low dielectric film are removed to form metal wires, plugs, vias, and the like.

Since copper has many advantages in terms of efficiency such as high integration, it is often used as a metal material for semiconductor wafers. It is a noble metal and a dual damascene structure, which is not selectively etched, and thus has a CMP process. This is used essentially. Copper forms a porous oxide layer composed of CuO, CuO ₂ , Cu (OH) _2, etc., including Cu ⁺ or Cu ²⁺ , which is a copper oxide ion during the CMP process. However, since copper is relatively weak compared to other materials such as TEOS (tetraethoxysilane) or tungsten made of silicon, and electrochemically sensitive to corrosion compared to tungsten, the polishing rate may be high, but instead scratches, and Dicing or erosion due to over-polishing occurs easily, and foreign materials such as oxide of polishing slurry and oxides generated during the polishing process penetrate the copper oxide layer, especially through porous membrane holes. The phenomenon occurs. This phenomenon may cause problems in the next process, such as a photolithography process, and in particular, in the case of a highly integrated circuit composed of 6-7 layers or more depending on the design of the wiring, depending on the flatness of each layer, Given that performance depends, it can be a cause of fatal defects.

In order to solve the problems described above, at least one complexing agent or a chelating agent is added to the CMP slurry for polishing copper wire to chelate Cu ⁺ and Cu ²⁺ ions in the copper oxide layer. Efforts have been made to prevent problems caused by foreign substances penetrating during the CMP process by strengthening the copper oxide film by removing pores due to porous film quality by complexing. Examples of such additives

Imidazoles such as triazole, benzotriazole, etc.

(imidazole) compounds and compounds having carboxyl groups (see, US Pat. No. 6,096,652).

However, due to the strengthening of the copper oxide layer, the polishing rate of the CMP process is reduced, and as a result, erosion and dishing are caused by overpolishing due to the delay of polishing time.

problems such as (ishing) have arisen. This resulted in an increase in manufacturing cost due to lowered yield and lowered productivity in semiconductor manufacturing.

Accordingly, the present invention is to solve the problems of the prior art as described above, the copper wiring surface oxidized by using a benzene compound as an oxidation inhibitor, an ammonium salt or an amine compound as a chelating agent, and a carboxyl compound as a complexing agent at the same time It is an object of the present invention to provide a CMP slurry for polishing copper wire, which can maintain a high polishing rate while preventing further oxidation by protecting the porous membrane of the film.

That is, the present invention comprises (a) fine metal oxide powder, (b) peroxide compound, (c) benzene compound, (d) ammonium salt or amine compound, (e) carboxyl compound and (f) deionized water. It provides a CMP slurry for polishing copper wiring.

Hereinafter, the present invention will be described in more detail.

The CMP slurry for polishing copper wirings of the present invention comprises (a) fine metal oxide powder, (b) peroxide compound, (c) benzene compound, (d) ammonium salt or amine compound and (e) carboxyl compound in deionized water. Prepared by dispersion, preferably

(a) 1 to 15% by weight of fine metal oxide powder;

(b) 0.1 to 10% by weight of peroxide compound;

(c) 0.01 to 0.5 wt% of a benzene compound;

(d) 0.01-0.5 wt% of ammonium salts or amine compounds; And

(e) 0.001-0.5 wt% of carboxyl compound

It includes.

The metal oxide fine powder (hereinafter referred to as component (a)) used in the present invention serves as an abrasive, and may be used conventionally used in CMP slurry, but preferably silica, as long as the object of the present invention is not impaired. A fine powder of at least one metal oxide selected from the group consisting of (SiO ₂ ), alumina (Al ₂ O ₃ ), ceria (CeO ₂ ) and titania (TiO ₂ ) is used.

It is preferable that the average particle size of the said component (a) is 500 nm or less at maximum, More preferably, it is 200 nm or less. If the particle size of the component (a) is larger than 500 nm, it is not preferable to use it because it may cause a decrease in the yield of semiconductor manufacturing due to overpolishing, scratching and the like.

The content of component (a) is preferably 1 to 15% by weight relative to the total slurry in terms of polishing rate and flatness required in the CMP process, more preferably 3 to 10% by weight.

The peroxide compound (hereinafter referred to as component (b)) used in the present invention serves as an oxidizing agent for oxidizing the copper surface, and is not particularly limited to the kind so long as the object of the present invention is not impaired, but preferably At least one compound selected from the group consisting of hydrogen peroxide, potassium peroxoate (potassuim periodate), potassium persulfate and potassium ferricyanide is used.

The content of the component (b) is preferably 0.1 to 10% by weight based on the total slurry, more preferably 1.5 to 5% by weight is added. If the content of component (b) is less than 0.1% by weight, the polishing rate is lowered.

It is not preferable because a line recess or a fitting phenomenon due to a corrosion phenomenon may occur, which may cause problems in semiconductor circuit operation.

Benzene-based compounds (hereinafter referred to as component (c)) used in the present invention serves to prevent further oxidation by protecting the porous membrane of the oxidized copper surface, preferably benzotriazole, benzoquinone ( at least one compound selected from the group consisting of benzoquinone), benzyl butyl phthalate, benzyl-dioxolane and salts thereof.

The content of the component (c) is preferably 0.01 to 0.5% by weight based on the total slurry, more preferably 0.05 to 0.1% by weight is added.

In the present invention, in order to further strengthen the copper oxide film, in addition to the benzene compound, an ammonium salt or an amine compound is used in combination with a carboxyl compound. The required selectivity, Cu: TaN: TEOS = 50 ~ 10: 1: 1, is achieved.

In the present invention, the ammonium salt or amine compound (hereinafter referred to as component (d)) serves as a chelating agent (chelating agent), preferably ammonium acetate, ammonium oxalate, ammonium formate, ammonium tart One or more compounds selected from the group consisting of ammonium tartrate, ammonium lactate, ammonium tetrahydrate, aminobenzotriazole, aminobutyric acid, aminoethylaminoethanol, aminopyridine and salts thereof, It is preferable that content is 0.01 to 0.5 weight% with respect to the whole slurry, More preferably, it is added at 0.05 to 0.1 weight%.

Meanwhile, the carboxyl compound (hereinafter, referred to as component (e)) serves as a complexing agent (complexing agent), preferably using acetic acid, formamide, propionic acid or malonic acid, the content of the total It is preferable that it is 0.001-0.5 weight% with respect to a slurry.

The CMP slurry of the present invention comprising the above-described components is very suitable for polishing copper or copper alloy which is a semiconductor wiring material.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example 1

70 g of fine silica powder (Aerosil 90G, Degussa), 908.9 g of deionized water, 0.5 g of benzotriazole, 0.5 g of ammonium acetate, 20 g of 50% (v / v) hydrogen peroxide solution and 0.1 g of acetic acid were added to a 2-liter polyethylene flask, The mixture was stirred by high speed stirring for 2 hours at a speed of 2,000 rpm. The mixture was dispersed once at 1,200 psi by high pressure dispersion to make a slurry. The slurry thus obtained was filtered through a 1 μm depth filter to complete the polishing slurry.

The polishing rate of the polishing slurry thus prepared was measured from the thickness change of the copper layer removed by polishing after polishing the copper-deposited 6-inch wafer for 2 minutes under the following conditions. Copper dishing and dielectric layer erosion were evaluated by polishing patterned wafers with lines of 0.36 μm line width at 0.27 μm intervals under the same conditions using the same polishing slurry. Polishing performance evaluation results are shown in Table 1 below.

[Polishing condition]

Grinding machine model: 6EC (Strasbaugh)

o Polishing condition:

-Pad Type: IC1000 / SubaⅣ Stacked (Rodel)

-Platen speed: 80rpm

Quill speed: 80 rpm

Pressure: 8 psi

Background pressure: 0psi

Temperature: 25 ℃

Slurry flow: 150 ml / min

Example 2

A polishing slurry was prepared in the same manner as in Example 1 except that the amount of ammonium acetate was increased to 1.5 g, and the polishing performance was evaluated. The results are shown in Table 1 below.

Example 3

A polishing slurry was prepared in the same manner as in Example 1, except that 0.5 g of ammonium formate was added instead of ammonium acetate, and the polishing performance was evaluated. The results are shown in Table 1 below.

Example 4

Except that the addition amount of ammonium formate in Example 3 was increased to 1.5g to prepare a polishing slurry in the same manner and to evaluate the polishing performance. The results are shown in Table 1 below.

Example 5

A polishing slurry was prepared in the same manner as in Example 1, except that 0.5 g of ammonium tartrate was added instead of ammonium acetate, and the polishing performance was evaluated. The results are shown in Table 1 below.

Example 6

Except that the amount of the ammonium tartrate was added to 1.5g in Example 5 to prepare a polishing slurry in the same manner and to evaluate the polishing performance. The results are shown in Table 1 below.

Comparative Example 1

Except for omitting ammonium acetate in Example 1 to prepare a polishing slurry in the same manner and to evaluate the polishing performance. The results are shown in Table 1 below.

Comparative Example 2

Except that acetic acid was omitted in Example 1 to prepare a polishing slurry in the same manner and to evaluate the polishing performance. The results are shown in Table 1 below.

Comparative Example 3

Except that acetic acid was omitted in Example 3 to prepare a polishing slurry in the same manner and to evaluate the polishing performance. The results are shown in Table 1 below.

Comparative Example 4

Except that acetic acid was omitted in Example 5 to prepare a polishing slurry in the same manner and to evaluate the polishing performance. The results are shown in Table 1 below.

division Ammonium salt Addition amount (g) Acetic acid Polishing Speed (Å / min) Copper dishing Dielectric Layer Erosion Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Ammonium acetate ammonium acetate ammonium formate ammonium formate ammonium tartrate ammonium tartrate-ammonium acetate ammonium formate ammonium tartrate 0.51.50.51.50.51.5-0.50.50.5 Additive Additive Additive Additive Additive --- 4,2004,5404,0604,3504,2104,9803,2503,9603,7104,210 210230340560350840N.D.N.D.N.D.N.D. 520550760835620250N.D.N.D.N.D.N.D.

Note N.D .: not determined

As described in detail above, using the polishing slurry of the present invention can achieve a high polishing rate while preventing problems such as dishing and erosion due to the porosity and low strength of the copper oxide film during the CMP process of copper wiring. .

Claims (7)

CMP for polishing copper wiring containing (a) fine metal oxide powder, (b) peroxide compound, (c) benzene compound, (d) ammonium salt or amine compound, (e) carboxyl compound and (f) deionized water Slurry. The method of claim 1, 1 to 15% by weight of the fine metal oxide powder; 0.1 to 10% by weight of the peroxide compound; 0.01 to 0.5% by weight of the benzene compound; 0.01 to 0.5% by weight of the ammonium salt or the amine compound; And The carboxyl compound is contained 0.001 to 0.5% by weight, CMP slurry for polishing copper wiring, the remainder being deionized water. The method according to claim 1 or 2, CMP slurry for polishing a copper wire, characterized in that the metal oxide is at least one selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), ceria (CeO ₂ ) and titania (TiO ₂ ). The method according to claim 1 or 2, The peroxide compound is hydrogen peroxide (hydrogen peroxide), potassium peroxate (potassuim periodate), potassium persulfate (potassuim persulfate) and potassium ferricyanide CMP slurry for polishing copper wiring, characterized in that at least one member selected from the group consisting of (potassium ferricyanide). The method according to claim 1 or 2, The benzene-based compound is benzotriazole, benzoquinone (benzoquinone), benzyl butyl phthalate, benzyl-dioxolane (Benzyl-dioxolane) and CMP slurry for polishing copper wirings, characterized in that at least one selected from the group consisting of salts thereof. The method according to claim 1 or 2, The ammonium salt or amine compound is ammonium acetate, ammonium oxalate, ammonium formate, ammonium tartrate, ammonium lactate, ammonium tetrahydrate, aminobenzotriazole, aminobutyric acid, aminoethylaminoethanol, amino CMP slurry for polishing copper wirings, characterized in that at least one selected from the group consisting of pyridine and salts thereof. The method according to claim 1 or 2, CMP slurry for polishing copper wiring, characterized in that the carboxyl compound is acetic acid, formamide, propionic acid or malonic acid.