KR100561568B1 - Composition for chemical mechanical polishing - Google Patents

Abstract

The present invention relates to a composition for CMP improved polishing uniformity, more specifically

(1) 0.1-50% by weight of a metal oxide,

(2) deionized water 50-99.9 wt%,

(3) a benzoquinone compound of formula (1) and

   0.001-3 parts by weight with respect to 100 parts by weight of one or more additives (1) + (2) selected from the group consisting of a quebrakititol-based compound of formula (2)

The present invention relates to a composition for CMP, comprising a planarization of a semiconductor wafer, because the composition for CMP of the present invention reduces the incidence of large particles in the slurry for CMP, thereby preventing or minimizing the generation of micro-scratches, thereby improving polishing uniformity. Useful for

[Formula 1]

[Formula 2]

Wherein n is an integer of 0-5.

Metal Oxide, Deionized Water, Benzoquinone Compound, Quebrachitol Compound, μ-Scratch

Description

Composition for CPM {COMPOSITION FOR CHEMICAL MECHANICAL POLISHING}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for chemical mechanical polishing (hereinafter referred to as CMP), and more particularly, to a benzoquinone compound or a quebraquitol compound in an abrasive composed mainly of deionized water and a metal oxide. It relates to a composition for CMP by adding a (quebrachitol compound) to prevent the formation of large particles of the slurry during the CMP process to prevent or minimize the formation of μ-scratch.

In recent years, as semiconductor devices have become higher performance and higher integration, they have entered the era of ultra large scale integration (hereinafter referred to as ULSI) represented by 256M byte and 1G byte DRAM. With the trend toward miniaturization, next-generation devices will require 0.18-0.12nm lines. In order to obtain a desired resolution in such a highly integrated photo process, it is necessary to increase the stepper performance, increase the lens numerical aperture, and shorten the wavelength of light. However, if these conditions are met, the depth of focus (DOF) is shallow and the resolution of the device surface is insufficient due to the step difference of the device surface.

On the other hand, when the wiring structure is miniaturized and a high density integrated circuit is to be obtained, the number of wiring layers needs to be multilayered. In the case of a logic element array (Logic), the number of layers is increased to 6-7 layers, and in the case of DRAM, the number of layers is 2-2. It will increase to the third floor. As the number of wiring layers increases, the surface structure of the device becomes more complicated, and the degree of surface irregularities also increases.

Planarization technology has emerged as an important technology to solve the problems caused by the reduction of the depth of focus margin and the multilayer structure of the wiring structure during lithography. This is because the surface planarized is not only easy to lithography and wiring but also these processes can be ideally performed. Conventional wafer planarization processes (such as Reflow / SOG Etch Back / ECR Depo & Etch) are mostly partial planarization techniques and are insufficient to realize wide area planarization. Among these, CMP is the planarization technique that has attracted attention as the most efficient technique that can realize wide area planarization.

The principle of the CMP technique is to supply a slurry of polishing liquid while the polishing material is brought into contact with the polishing pad surface to chemically react the surface of the polishing material and to physically move the polishing pad and the polishing material relative to each other. It is to flatten the uneven portion of the material to be polished.

The main components of the composition for CMP include deionized water, metal oxides, pH or bases for pH adjustment, and oxidizing agents for improving the polishing rate. Among them, metal oxides include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), cerium oxide (CeO ₂ ), zirconium oxide (ZrO ₂ ), and titanium oxide (TiO ₂ ), which are fumed or sol-gel. It is manufactured by the (Sol-Gel) method. Known matters about these slurry compositions are classified according to types and additives of metal oxides, for example, slurry composed of silica / amine as slurry for polishing an insulating layer (US Pat. No. 4,169,337), slurry composed of silica quaternary ammonium salt (US Patent No. 5,139,571), Alumina / H202 (US Patent No. 5,244,523), Silica / K ₂ Fe (CN) ₆ (US Patent No. 5,340,370), Slurry for Polishing Metal Wires and Plugs (European) Patent No. 786,504), slurry consisting of metal oxide / oxidant / fluorine ions (WO Patent No. 9,743,070) and the like. The slurries are slurries that are actually used for semiconductor production according to the material to be polished and the CMP process, and the polishing rate, flatness, and selectivity of the polishing performance evaluation items are somewhat satisfactory. Has a problem that a large amount is generated. Defects such as μ-scratches on the material to be polished after CMP are mostly caused by some large abrasive particles contained in the slurry. The size of such large particles is about several micrometers (1-10 micrometers), which may be caused by aggregation due to a change in the dispersion state of the abrasive in the slurry or drying as the slurry is exposed to the outside air. In addition, a compound capable of minimizing the number of large particles generated by agglomeration by preventing a change in dispersion state of the abrasive and buffering the generated large particles in contact with the material to be polished is required. In particular, in the case of thin trench isolation (hereinafter referred to as STI) process, the occurrence of μ-scratch is fatal because it causes the device to fail, and the structure forming the trench is thin and fine at about 200 nm, causing the μ-scratch to occur. This is because the STI structure itself is destroyed and affects trenches or capacitors formed on the upper layer. Therefore, in the CMP process, it is very important to remove the micro-scratch.

In order to solve the above problems, an object of the present invention is to add a benzoquinone compound or a quracrachitol compound to an abrasive containing deionized water and a metal oxide as a main component. It is to provide a composition for CMP which prevents the formation of μ-scratches by preventing the formation of large particles of the CMP slurry during the polishing (hereinafter referred to as CMP) process.

That is, the object of the present invention

(1) 0.1-50% by weight of a metal oxide,

(2) 50 to 99.9% by weight of deionized water,

(3) a benzoquinone compound of formula (1) and

   0.001-3 parts by weight with respect to 100 parts by weight of one or more additives (1) + (2) selected from the group consisting of a quebrakititol-based compound of formula (2)

It is to provide a composition for CMP comprising a.                         

Wherein n is an integer of 0-5.

Hereinafter, the present invention will be described in detail.

Metal oxides used in the present invention include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), cerium oxide (CeO ₂ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), and the like. It is manufactured by the Sol-Gel method. The particle size of the metal oxide particles is 10-100 nm, preferably 20-60 nm. If the particle size of the metal oxide particles is less than 10nm, the polishing rate is lowered and the productivity is not good.If the particle size exceeds 100nm, the polishing rate is faster, which is advantageous in terms of productivity, but the dispersion becomes difficult due to large Since large particles are present in a large amount, it is not good to increase the incidence of μ-scratch.

The preferable particle size in the aqueous solution dispersion state of the said metal oxide particle is 50-250 nm. If the particle size is less than 50 nm, the polishing rate is slow and not good in terms of productivity. If the particle size is more than 500 nm, the micro-scratch increases not only rapidly but also the sedimentation stability is lowered, so that it is settled at room temperature for more than 30 days. Since this happens, a pretreatment step (stirring step) is additionally required in the CMP process, which is not good.

The content of the metal oxide is 0.1 to 50% by weight based on the whole composition, preferably 1 to 25% by weight. Usually, when the slurry using silica as an abrasive is used for polishing a semiconductor wafer insulating layer, the content is 9-15% by weight, and the content is 1-15% by weight for polishing metal wires and plugs.

In the present invention, at least one of the benzoquinone compound of formula (1) and the quebraquitol compound of formula (2) may be used as an essential additive in the polishing composition.

[Formula 1]

[Formula 2]

Wherein n is an integer of 0-5.

The content of the compounds is 0.001 to 3 parts by weight, preferably 0.01 to 1 part by weight based on 100 parts by weight of the metal oxide and deionized water. If the content is less than 0.001 part by weight, the effect of the present invention cannot be expected. If the content is more than 3 parts by weight, the additive effect is neither improved nor economically good. In the benzoquinone compound, a carbonyl substituent may be substituted at the positions (1, 4), (1, 3) and (1, 2), and the compound at the position (1, 4) is preferable. It is preferable that n is 0-1 for a quebrakititol type compound.

Since the benzoquinone compound or the quercapitol compound have moisture and dispersibility

1) Prevents the formation and aggregation of metal oxides to prevent the formation of large particles that cause μ-scratches,

2) Reduces μ-scratches because it prevents clogging or crusting in transportation and storage, transportation / pipe transportation / pipe systems, etc.

3) It makes the abrasive to be uniformly distributed, thereby reducing the particle size dispersion width and improving the flatness of the material to be polished.

4) improves the flatness of the material to be polished by improving the fluidity of the polishing liquid slurry during polishing to make uniform contact with the wafer surface,

5) It facilitates electron transfer, stabilizes OH ^- ions in the slurry, and at the same time quickly transfers the slurry's chemical properties to the wafer during polishing.

The addition order thereof is not particularly limited, and may be any case before or after the dispersion of the metal oxide, and further addition to the commercially available slurry composition has the same effect. Conventional CMP slurries tend to induce a large amount of μ-scratches, especially when used after long-term storage, whereas CMP slurries of the present invention to which the additive compound is added have been stored for 6 months or more, and then they generate μ-scratches. Polishing performance remains constant regardless of storage period, such as no increase in degree. In addition, since the dispersion stability is increased when the additive compound is used, a side effect of increasing sedimentation stability is obtained.

The CMP composition may additionally add a second additive depending on the type of material to be polished. For example, when polishing an insulating layer of a wafer, a base such as KOH or an amine salt may be added to the metal wire and the plug. In the case of polishing and the like, an oxidizing agent and the like can be used together with an acid such as H ₂ SO ₄ , HNO ₃ , and CH ₃ COOH.

The composition for CMP of the present invention is 0.001-3 parts by weight of benzoquinone or quebraquitol based on 0.1-0.5% by weight of the metal oxide and 50-99.9% by weight of deionized water with respect to 100 parts by weight of the metal oxide and deionized water. It is prepared by adding a compound.

The present invention will be described with reference to the following examples, and the following examples are only described for the purpose of illustrating the present invention and are not intended to limit the protection scope of the present invention.

Example 1

(1,4) -benzoquinone After addition of 1 g (0.1 parts by weight), it was counter-impacted and dispersed at 13,000 psi. A 13 wt% KOH solution was added so that the pH of the slurry thus obtained was 11, filtered using a filter having a depth of 1 μm, and polished for 2 minutes under the following conditions to remove the polishing rate from the change in thickness removed by polishing. And flatness was measured, and the number of μ-scratches was measured using a KLA (TENTON Corporation) instrument. The results are shown in Table 1.

* Grinding Machine Model: 6EC (STRASBAUGH)

* Polishing target: 6 "wafer coated with PE-TEOS

* Polishing condition:

-Pad type; IC1000 / SubaIV Stack type (Rodel)

Platen speed; 120 rpm

Quill speed; 120 rpm

- pressure ; 6 psi

Back pressure; 0psi

- Temperature ; 25 ℃

-Slurry flow rate; 150ml / min

Example 2

Polishing performance was evaluated after preparing the slurry in the same manner as in Example 1, except that Quebraquitol was used instead of (1,4) -benzoquinone, and the results are shown in Table 1.

Examples 3-5

Instead of fumed silica, other metal oxides shown in Table 1 were used, and the polishing performance was evaluated in the same manner as in Example 1 except that 1 part by weight of (1,4) -benzoquinone was added. Is shown in Table 1.

Examples 6-8

Instead of fumed silica, other metal oxides shown in Table 1 were used, and the polishing performance was evaluated in the same manner as in Example 1, except that 1 part by weight of Quebrachitol was added, and the results are shown in Table 1. It was.

Examples 9-11

After storing the slurry composition prepared in the same manner as in Example 1 for 1 day, 60 days and 120 days, the polishing performance in each case was compared to determine whether the polishing performance (μ-scratch) changed after long term storage. The results are shown in Table 2.

Comparative Example 1-7

In Examples 1 and 2, the slurry was prepared in the same manner as in Example 1 using the metal oxides shown in Table 3 without adding (1,4) -benzoquinone or quebrachitol, and the polishing performance was evaluated. In Table 3, Comparative Examples 5 to 7 evaluated the polishing performance after storage for 1 day, 60 days, and 120 days, respectively.

* 실시예 9 내지 실시예 11 : 각각 1일, 6일, 120일 보관

Examples 9-11: 1 day, 6 days, 120 days storage, respectively

* 비교예 5 내지 비교예 7 : 각각 1일, 60일, 120일 보관

Comparative Examples 5 to 7: 1 day, 60 days, 120 days storage, respectively

As can be seen from the results of the above examples, the composition for CMP of the present invention has a significant reduction in the number of μ-scratches and the improved polishing uniformity.

Claims (4)

(1) 0.1-50% by weight of a metal oxide, (2) 50 to 99.9% by weight of deionized water, (3) A composition for CMP comprising 0.001-3 parts by weight of a quebrakititol compound of formula (2) based on 100 parts by weight of (1) + (2). [Formula 2]

Wherein n is an integer of 0-5. The metal oxide of claim 1, wherein the metal oxide is selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), cerium oxide (CeO ₂ ), zirconium oxide (ZrO ₂ ), and titanium oxide (TiO ₂ ). CMP composition, characterized in that. The composition for CMP according to claim 1, wherein the metal oxide has a particle size of 10-100 nm. The composition for CMP according to claim 1, wherein the average particle size of the secondary particles of the metal oxide is 50 to 500 nm.