KR100565425B1 - Slurry Composition for Chemical Mechanical Polishing of Copper - Google Patents

Abstract

The present invention relates to a chemical mechanical polishing (CMP) slurry composition for copper wiring, in which the selectivity between the oxide layer and the metal layer is improved and there are no defects such as dishing and erosion of the oxide film during polishing, and more particularly, fine powder and peroxide of the metal oxide. The present invention relates to a CMP slurry composition for copper wiring comprising a compound, a carboxylic acid compound having at least one carboxyl group, polyethylene glycol, an organic compound additive, and deionized water. The composition according to the present invention can significantly reduce the polishing defects such as oxide erosion, corrosion, pits, dishing, scratches, etc. generated during the CMP process due to the large selectivity between the copper wiring layer and the oxide layer.

Description

CMP slurry composition for copper wiring {Slurry Composition for Chemical Mechanical Polishing of Copper}

The present invention relates to a chemical mechanical polishing (CMP) slurry composition for copper wiring, in which the selectivity between the oxide layer and the metal layer is improved and free from defects such as dishing and erosion of the oxide layer during polishing, and more particularly, metal oxides, peroxide compounds, The present invention relates to a slurry composition for copper wiring CMP containing a carboxylic acid compound having at least one carboxyl group, polyethylene glycol, an organic compound additive, and deionized water.

In the multi-layer polishing process or the double damascene process of the integrated circuit developed to increase the integration degree of the IC circuit, the CMP process is mainly used for the planarization of the wafer surface. The CMP process is a polishing method for flattening the wafer surface using a polishing pad and a slurry during semiconductor manufacturing. An orbital motion in which a slurry composition is dropped on a polishing pad made of polyurethane and is in contact with a wafer is mixed with rotational and linear motion. And a process for polishing the wafer mechanically and chemically, wherein the slurry is generally an abrasive with physical polishing and an active component with chemical polishing, such as an etchant. Or an oxidant, thereby physically and chemically etching the protruding portions on the wafer surface to provide a flat surface. To describe the CMP process in detail, first, a low dielectric film such as SOG or BPSG, O3-TEOS, USG, P-TEOS, low-k, FOX, etc. is deposited on a wafer or a metal layer, and a photolithography process is performed. A trench is formed in the low dielectric layer using a dry etch process, and then titanium, titanium nitride, and tantalum are used to improve the adhesion between the metal layer and the low dielectric layer. a barrier layer such as tantalum) and tantalum nitride is deposited. Then, the metal wire or plug is filled with a conductive material such as tungsten, aluminum, or copper and deposited. 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.

CMP slurry can be divided into insulating layer polishing slurry and metal polishing CMP slurry according to the polishing object. Metal wire polishing slurry should have difference in polishing speed between metal layer and insulating layer, and high polishing speed is required for metal wiring. In the insulating layer, a low polishing rate is required. This is because when the speed difference is small, only a portion having a high pattern density may have a high polishing rate, and defects such as erosion may occur at a high pattern density. Therefore, the polishing rate of the insulating layer should be lowered to prevent the partial polishing rate increase phenomenon.                         

On the other hand, as for the interlayer insulating film in the Cu wiring, SiO ₂ or FSG (SiOF, k = 3.4 to 3.6) was initially used. In this case, the SiN film (k was used as an etching stopper film in the double damascene process. = 7) you need to insert it in the middle. In addition, when the end point endpoint of CMP is difficult, a SiN film is also set as a CMP stopper film. In the second generation process of Cu, a low-k film around k = 2.5 is employed. In particular, by employing an organic low-k film, SiO ₂ can be used as an etch stopper film. Organic low-k membranes before and after k = 2.5 are roughly divided into three groups: non-F polymers (SiLK, BCB, FLARE, PAE, etc.), F polymers (aC: F, Parylene-F, etc.), and organic SOG. Among them, non-F polymers such as SiLK and FLARE, which are excellent in heat resistance and degassing, are being considered. On the other hand, since Cu wiring is adopting a double damascene process from the viewpoint of process cost, it is likely that a weak point of a CMP process such as dishing or erosion may appear, and is a soft metal compared to W wiring. There is a disadvantage that a lot of surface scratches can occur when polishing.

The CMP process has achieved some of the elements required to form copper wires and plugs or vias. However, as mentioned above, problems such as polishing rate and corrosion still remain. Manufacturing costs due to degradation are high. Accordingly, there is a need in the art for a CMP slurry having excellent selectivity according to the quality of the abrasive film and less occurrence of defects and dishing during metal polishing.

The present inventors have diligently studied to solve the above problems, and as a result, the selection ratio of the CMP slurry composition for copper wiring including a metal oxide, a peroxide compound, a carboxylic acid compound having one or more carboxyl groups, polyethylene glycol, an organic compound additive, and deionized water is It has been found to be greatly improved and that the defects in polishing are significantly reduced, thus completing the present invention.

After all, the present invention is to provide a metal CMP slurry that can greatly improve the problem of the selectivity ratio and greatly reduce the incidence of defects during polishing.

One aspect of the present invention for achieving the above object relates to a CMP slurry composition for copper wiring comprising a metal oxide, a peroxide compound, a carboxylic acid compound having at least one carboxyl group, polyethylene glycol, an organic compound additive and deionized water.

Another aspect of the invention relates to a method of polishing a metal using the composition.

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

The metal oxide used as the abrasive in the present invention is one or more selected from the group consisting of silica, alumina, ceria, zirconia, and titania, and any one produced by any of the fume method and the sol-gel method may be used. The use of silica is most preferred in view of economics and wafer contamination. these The primary particle size (TEM measurement result) of the metal oxide is 10 to 70 nm, preferably 20 to 40 nm, and the specific surface area is preferably 100 to 300 m ² / g. If the primary particles are too small, less than 10 nm, the removal rate is low, which is undesirable in terms of throughput. On the contrary, when the primary particles are larger than 70 nm, the removal rate is increased, which is advantageous in terms of productivity, but difficult to disperse and large. It is not preferable because a large amount of particles are present to cause a large amount of μ-scratches. These metal oxides are preferably dispersed such that secondary particles in an aqueous dispersion have an average size of 100 to 200 nm, and in order to maintain dispersion stability for a long time, the hydroxyl group concentration on the surface of the metal oxide is 0.5 to 4 ea / nm 2. desirable. The content of the metal oxide in the slurry is 0.1 to 50% by weight, preferably 1 to 50% by weight of the total weight of the slurry.

The polishing mechanism in metal CMP has a polishing mechanism by a continuous and repeated process of oxidizing the metal surface to form an oxide film and removing the oxide film by chemical and physical action of the CMP slurry. Oxidizing agents that oxidize surfaces include hydrogen peroxide, potassium ferricyanide, potassium dichromate, potassium iodate, potassium bromate, and vanadium trioxide. (vanadium trioxide), hypochlorous acid, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, magnesium hypochlorite, ferric nitrate , KMgO ₄ and the like. Preferably, hydrogen peroxide is used, wherein the addition amount is 0.1 to 5% by weight of the total weight of the slurry, more preferably 0.1 to 1.0% by weight. If more than 5% by weight is added, the polishing rate is increased, but line recess or pitting due to corrosion may occur, which may cause problems in the operation of the semiconductor circuit. At the time of addition, the polishing rate may be reduced to have the above-mentioned problems.

The composition according to the present invention chelates or complexes Cu ⁺ and Cu ²⁺ ions, which are copper oxide ions generated when forming an oxide layer using a carboxylic acid compound as a complexing agent, to strengthen the oxide layer. By preventing the infiltration of foreign substances and maintaining a high polishing rate to solve problems such as dishing or erosion by overpolishing, examples of the carboxylic acid compounds that can be used include citric acid, lactic acid, lactic acid, Malonic acid, tartaric acid, succinic acid, acetic acid, oxalic acid, amino acid, amino sulfuric acid, phosphoric acid acid), phosphonic acids and salts thereof. Preferably ammonium tartrate is used, and the addition amount is in the range of 0.1 to 5% by weight, more preferably 0.1 to 1% by weight of the total weight of the slurry.

The slurry according to the present invention contains polyethylene glycol, which is intended to improve the dispersion stability of the metal oxide, which is an abrasive. Preferably, polyethylene glycol having a molecular weight of 15,000 to 25,000 is used. The amount of the polyethylene glycol added is 0.01 to 0.1% by weight based on the total weight of the composition.

The slurry according to the invention comprises an amine compound (ie ammonium or amine series and their salts), which prevents the abrasive particles from adsorbing on the metal surface. As polishing of the Cu wiring proceeds and the barrier layer begins to be exposed to the surface, an additive is needed so that the polishing does not proceed rapidly any further. In the present invention, TMAH (Tetramethylammoniumhydroxide), nA, which is adsorbed on nitride / oxide surfaces such as TaN and SiO ₂ and does not react with metal surfaces such as Cu and inhibits the progress of polishing, n -Butylamine, or trimethanolamine. The amount of each of these additives added is suitably about 0.01 wt% to 0.5 wt% of the total weight of the slurry.

The slurry composition according to the present invention can be usefully used in the CMP process for metal polishing in the semiconductor process, preferably can be used for polishing of copper metal.                     

Hereinafter, the structure and effect of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention, and are not intended to limit the scope of the present invention.

EXAMPLE

Example 1

A mixture of 400 g of silica, 3526 g of deionized water, 40 g of ammonium tartrate, 2.0 g of polyethylene glycol (PEG: 15,000 molecular weight), 12 g of hydrogen peroxide, and 20 g of TMAH was added to a mixture at high speed of stirring at 2,000 rpm for 2 hours in a 5 L polyethylene flask. Dispersion was performed once at 1,200 psi using a high pressure dispersion method. The slurry thus obtained was filtered using a 1 μm depth filter, and then polished for 1 minute under the following conditions, and then the polishing rate was measured from the thickness change removed by polishing. The results are shown in Table 1.

   o Grinder Model: 6EC (STRASBAUGH)

   o Polishing condition:

    Pad type: IC1400 / SubaIV Stacked (Rodel)

    Platen Speed: 80 rpm

    Quill Speed: 80 rpm

    Pressure: 8 psi

    Back Pressure: 0 psi

    -Temperature: 25 ℃                     

    Slurry flow: 150 ml / min

   o Polishing target:

6-inch wafer with copper

Examples 2 to 3

A polishing slurry was prepared in the same manner as in Example 1 except that the amount of TMAH added in Example 1 was as shown in Table 1 below, and the polishing performance was evaluated. The results are shown in Table 1.

Example 4

Except that n-butylamine was added instead of TMAH in Example 1 to prepare a polishing slurry in the same manner as in Example 1 and evaluated the polishing performance.

The results are shown in Table 1.

Example 5

A polishing slurry was prepared in the same manner as in Example 1 except that triethanol amine was added instead of TMAH in Example 1, and the polishing performance was evaluated. The results are shown in Table 1.

Comparative Example 1

Except that TMAH was not added in Example 1 to prepare a polishing slurry in the same manner as in Example 1 and evaluated the polishing performance.

The results are shown in Table 1.

division Organic compound additive Addition amount (g) Cu layer polishing rate (Å / min) barrier layer (TaN) polishing rate (Å / min) Oxide layer polishing rate (Å / min) Example 1 Example 2 Example 3 Example 4 Example 5                                                  Comparative Example 1 TMAH TMAH TMAH n-butylamine triethanolamine                                                  - 20g 12g 4g 20g 20g                                                  - 4,410 4,340 4,250 4,350 4,300                                                  4,120 30 260 380 69 70                                                  265 77 110 150 88 98                                                  325

From the table, it can be seen that in the case of the composition according to the present invention, the selectivity is excellent.

As described in detail above, in the slurry composition of the present invention, the selectivity of the metal layer such as Cu, the TaN layer, and the oxide layer is greatly improved, thereby preventing problems such as dishing and erosion of the copper oxide layer during the CMP process of copper wiring. At the same time, it is possible to achieve a high polishing rate.

Claims (5)

Selected from 0.1 to 50% by weight of metal oxide, 0.1 to 5% by weight of peroxide compound, 0.1 to 5% by weight of carboxylic acid compound having at least one carboxyl group, 0.01 to 0.1% by weight of polyethylene glycol, TMAH, n-butylamine, trimethanolamine Slurry composition for metal CMP comprising 0.01 to 0.5% by weight of at least one organic compound additive and deionized water. The method of claim 1, wherein the metal oxide is selected from the group consisting of silica, alumina, ceria, zirconia, titania and mixtures thereof, the primary particle size is 10 ~ 70nm, the specific surface area is 100 ~ 300m ² / g, The size of the secondary particles is 100 to 200nm, the composition characterized in that the hydroxyl concentration of the surface is 0.5 to 4 ea / nm ² . The method of claim 1, wherein the peroxide compound is hydrogen peroxide (hydrogen peroxide), potassium ferricyanide (potassium ferricyanide), potassium dichromate (potassium chromium), potassium iodate (potassium iodate), potassium bromate (potassium bromate), Vanadium trioxide, hypochlorous acid, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, magnesium hypochlorite, iron nitrate (ferric nitrate), or KMgO ₄ , the carboxylic acid compound is citric acid, lactic acid, malonic acid, tartaric acid, succinic acid, acetic acid, Oxalic acid, amino acid, amino sulfuric acid, phosphoric acid, phosphonic acids or salts thereof Characterized in that the composition. The composition of claim 1, wherein the polyethylene glycol has a molecular weight of 15,000 to 25,000. A metal polishing method using the composition according to any one of claims 1 to 4.