KR100366304B1 - Composition for chemical mechanical polishing of insulating layer in semiconductor wafer - Google Patents

Abstract

The present invention relates to a composition for chemical mechanical polishing (hereinafter referred to as CMP) prepared by adding a pyridine-based compound to an abrasive composed mainly of deionized water and a metal oxide, and more specifically,

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

(B) 50-99.9 wt% of deionized water,

(C) 0.001-10 parts by weight based on 100 parts by weight of the pyridine compound (A) + (B)

It relates to a composition for chemical mechanical polishing of a semiconductor wafer insulating layer comprising a.

The composition according to the present invention is useful for use as a semiconductor wafer abrasive because it reduces the occurrence of μ-scratch, which is a surface defect that can occur after polishing.

Description

COMPOSITION FOR CHEMICAL MECHANICAL POLISHING OF INSULATING LAYER IN SEMICONDUCTOR WAFER}

The present invention relates to a composition for chemical mechanical polishing (hereinafter referred to as CMP). More specifically, the present invention minimizes the surface defects that can occur in the polished material after polishing by adding a pyridine-based compound to the abrasive mainly composed of deionized water and a metal oxide, thereby reducing the occurrence of surface defects, ie, scratches. And a chemical mechanical polishing composition of a semiconductor wafer insulating layer which improves the flatness of the material to be polished after polishing.

The Chemical Mechanical Polishing Process (hereinafter referred to as CMP Process), developed and introduced by IBM in the late 1980s, is used to planarize or pattern semiconductor wafers using both chemical and mechanical interactions. . This CMP is a polishing process in which mechanical and chemical actions simultaneously interact. Highly integrated semiconductor devices are fabricated by forming a pattern while repeatedly depositing a conductor material and an insulator material. If the wafer surface is not planarized during pattern formation, many problems arise in forming a new pattern layer in a lithography process. For example, in the third generation version of 64M DRAM, metal layers are formed in three layers. If each layer is not uniform, it is diffusely reflected and the photoresist pattern is not formed accurately. In the deposition of metal or oxide of each layer, the deposition state is not uniform, causing problems such as disconnection. In particular, as the thin trench isolation process (STI) is expanded and applied, the importance of full area planarization is increasing in the lithography process. The most efficient process known to date is CMP. Conventional wafer planarization process (SOG Etch Back / ECR Depo Etch, etc.) is complicated and requires two to five steps, whereas CMP process can be finished by only one polishing and cleaning process. However, there is a disadvantage that it is not suitable if the size of the wafer is increased or the metal is replaced with copper.

In the CMP process, the wafer is polished by the polishing pad and the polishing liquid slurry. In other words, the wafer is polished by rotating in a polishing table attached to a pad, and the wafer mounted on the head is pressed at a constant pressure while rotating and oscillating at the same time by surface tension or vacuum. The head portion applies a predetermined pressure to the polishing table to contact the wafer surface with the pad, and the slurry of the polishing liquid flows through the minute gaps (pores of the pad) between the contact surfaces, so that the surface of the polishing liquid particles and the pad inside the slurry. Mechanical polishing is performed by the projections and chemical polishing is performed by the chemical component in the slurry. That is, when the contact is made from the upper part of the protrusion of the polishing apparatus by the pressure applied to the pad and the wafer in the CMP process, and the pressure is concentrated on this part, and the surface polishing speed is relatively increased, the uneven portion is the front of the wafer as the processing proceeds. Flattening is achieved by uniformly polishing over.

In general, the polishing composition used in the semiconductor CMP process is composed of deionized water, metal oxides and other additives, and the polishing liquid slurry is classified into three types according to the material to be polished. In other words,

1) Monocrystalline Silicon Polishing Slurry

2) Insulation layer polishing slurry

3) Slurry for polishing metal wires and plugs

Metal oxides used as abrasives in these compositions include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), cerium oxide (CeO ₂ ), and zirconium oxide (ZrO) prepared by fuming or sol-gel. ₂ ), titanium oxide (TiO ₂ ), etc. are mainly used, and also include a base or acid for adjusting pH, an oxidizing agent for improving polishing rate, and a stabilizer for stabilizing slurry. 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), Silicon Nitride / Dicarboxylic Acid (EP Patent No. 786,504) and slurry consisting of metal oxide / oxidant / fluorine ions (WO Patent No. 9,743,070). 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.

The micro-scratch on the wafer surface after wafer polishing is also caused by factors such as platen or quill speed and pressure of the polishing machine, but most of the micro-scratches (1-10 μm) contained in the slurry It is known to be caused by "large particles" of size, which can also cause the settling of the slurry. There exist the following as a cause of generation of such a big particle.

1) Aggregation or Agglomerization

2) partial drying in container

3) sudden changes in temperature and pH

4) Clogging or crusting in transportation and piping systems

The generation of large particles produced by the aggregation or agglomeration of 1) depends on the dispersion method and the degree of dispersion during slurry preparation. The large particles produced by the above 2) to 4) are generated due to environmental changes during handling, such as transportation and storage, regardless of the dispersion method and the degree of dispersion, so there are many problems in handling the CMP slurry. CMP slurries have a direct impact on the polishing rate, the flatness of the material to be polished and the occurrence of scratches in the CMP process. Therefore, there is an urgent need to improve the problems caused by the conventional slurry for CMP polishing liquids.

An object of the present invention is to minimize the size of the slurry particles in order to solve the above problems, the semiconductor wafer insulating layer to reduce the occurrence of surface defects, that is, micro-scratches that can occur after polishing and to improve the flatness of the polishing material after polishing It is to provide a chemical mechanical polishing composition.

That is, the present invention

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

(B) 50-99.9 wt% of deionized water,

(C) 0.001-10 parts by weight based on 100 parts by weight of the pyridine compound (A) + (B)

It provides a chemical mechanical polishing composition for a semiconductor wafer insulating layer comprising a.

Hereinafter, the present invention will be described in detail.

The metal oxide (hereinafter referred to as component (A)) used in the present invention is the main component of the composition for CMP along with deionized water. Examples of the component (A) 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 gel (Sol-Gel) method. Although the particle size of the primary particle of the said component (A) is 10-100 nm, Preferably it is 20-60 nm (BET measurement result). If the particle size of the primary particles is less than 10nm, the polishing rate is slow and the productivity is not good, and if the particle size exceeds 100nm, the polishing rate is faster, which is advantageous in terms of productivity but difficult to disperse large Since large particles are present in a large amount, it is not good to increase the incidence of μ-scratch.

The preferred particle size of the secondary particles of the component (A), that is, particles in an aqueous solution dispersion state, is 50 to 250 nm. If the particle size is less than 50 nm, the polishing rate is slow, which is not good in terms of productivity. If the particle size is larger than 250 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 one week. Since this happens, a pretreatment step (stirring step) is additionally required in the CMP process, which is not good.

The content of component (A) is 0.1-50% by weight based on the total composition, and the preferred content is 1-25% by weight. Usually, when a polishing liquid slurry using silica as an abrasive is used for polishing a semiconductor wafer insulating layer, the content is 9-15% by weight.

In the present invention, deionized water (hereinafter referred to as component (B)) is used in an amount of 50 to 99.9% by weight based on the total composition.

The pyridine-based compound (hereinafter referred to as component (C)) used in the present invention is pyridine-4-methanol, pyridine-N-oxide, pyridine-3-sulfonic acid, pyridine-2-carboxaldehyde, pyridine-3- It may be a compound selected from the group consisting of carboxaldehyde, pyridine-3-carboxylic acid, pyridine-4-carboxylic acid. The content of the component (C) is preferably 0.001-10 parts by weight based on 100 parts by weight of the component (A) + (B). If the content is less than 0.001 parts by weight can not achieve the object of the present invention, if the content is more than 10 parts by weight does not improve the effect due to the addition of the pyridine-based compound is uneconomical Not good. The said component (C) can also be used individually or in mixture. It is difficult to explain in detail about the fact that the incidence of µ-scratch is reduced by adding the component (C), but it is generally considered to be due to the following reasons. That is, since the component (C) has a moisturizing property, it is possible to prevent agglomeration and agglomeration of the metal oxide in the CMP composition components of the present invention to generate large particles. It is thought to be because it prevents clogging or crusting in transportation and storage, transportation and piping systems.

The order of addition of the additives is not particularly limited and is possible at any time before or after dispersing the metal oxide, and the effect is the same even if further added to a commercially available polishing liquid slurry composition.

Conventional semiconductor wafer polishing liquid slurry tends to generate a large amount of mu-scratch especially when used after long-term storage, whereas the polishing slurry using the additive has a high mu-scratch incidence even when stored for 6 months or more. The polishing performance remains constant regardless of the storage period, such as no increase. In addition, since the dispersion stability is increased when using the additive, it is possible to obtain a side effect of increasing the sedimentation stability than when not used.

The polishing composition may be used by additionally adding a second additive. For example, a basic substance such as KOH or an amine salt may be added and used.

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

A mixture of 130 g of commercially available Aerosil 200 (Degussa), 18 g of 20% -KOH solution and 860 g of deionized water was premixed in a 2-liter polyethylene flask at 1000 rpm for 2 hours and then 1 g of pyridine-4-methanol. (0.1 parts by weight) was added and then dispersed at 1500 rpm for 1 hour using a batch-type dynomill containing 500 g of 2 mm glass beads. The pH of the resulting slurry was adjusted to pH 11 with 13 wt% KOH solution, filtered using a filter having a thickness of 1 μm, and then ground for 2 minutes under the following conditions. Then, the polishing performance, that is, the polishing rate, the flatness and the number of micro-scratches were measured through the thickness change of the polished material formed as a result of polishing, and the results are shown in Table 1.

Examples 2-7

Except for using pyridine-4-methanol other pyridine-based compounds shown in Table 1 was carried out in the same manner as in Example 1, the results of the evaluation of the polishing performance is shown in Table 1.

Examples 8-11

Except for fumed silica (metal oxide) as shown in Table 1 was used in the same manner as in Example 1 except that the pH was changed after dispersion, the results of the evaluation of the polishing performance is shown in Table 1 It was.

Examples 12-14

In order to determine whether the polishing performance (μ-scratch incidence) changes after long-term storage, the polishing performance of the slurry prepared in the same manner as in Example 1 was evaluated after 1 day, 7 days, and 30 days, and the results were evaluated. Shown in

Comparative Example 1

Except that pyridine-4-methanol was not added, it was carried out in the same manner as in Example 1, and the evaluation results for the polishing performance are shown in Table 2.

Comparative Example 2

Except not adding pyridine-4-methanol, the same process as in Example 8 was carried out, and the results of the evaluation on the polishing performance are shown in Table 2.

Comparative Example 3

Except not adding pyridine-4-methanol, the same process as in Example 9 was carried out, and the results of the evaluation on the polishing performance are shown in Table 2.

Comparative Example 4

Except that pyridine-4-methanol was not added, it was carried out in the same manner as in Example 10, and the evaluation results on the polishing performance are shown in Table 2.

Comparative Example 5

Except that pyridine-4-methanol was not added, it was carried out in the same manner as in Example 11, and the results of evaluation on the polishing performance are shown in Table 2.

Comparative Example 6-8

Except not adding pyridine-4-methanol, each was carried out in the same manner as in Example 12-14, and the evaluation results on the polishing performance are shown in Table 3.

[Polishing condition]

* Pad Type: IC1000 / SubaIV Stack Type (Rodel)

* Platen and quill speed: 120rpm

* Pressure: 6psi

* Back pressure: 0psi

* Temperature: 25 ℃

* Slurry Flow Rate: 150ml / min

* Grinding Machine Model: 6EC (STRASBAUGH)

[Property evaluation method]

* KLA (TENCOR Co., Ltd.) was used to measure the number of μ-scratch occurrences.

As confirmed through the results of Table 1 and Table 2, the composition for CMP of the present invention has a particle size is reduced compared to the conventional polishing composition, which is a surface defect that can occur on the polishing material after polishing and The flatness of the material to be polished has the advantage of being improved.

Claims (4)

(A) 0.1-50% by weight of a metal oxide, (B) 50-99.9 wt% of deionized water, (C) 0.001-10 parts by weight based on 100 parts by weight of the pyridine compound (A) + (B) Chemical mechanical polishing composition of a semiconductor wafer insulating layer comprising a. The method 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 ), titanium oxide (TiO ₂ ). A chemical mechanical polishing composition of a semiconductor wafer insulating layer, characterized in that. 2. The chemical mechanical polishing composition of claim 1, wherein the particle size of the primary particles of the metal oxide is 10-100 nm, and the particle size of the secondary particles is 50-250 nm. The pyridine-based compound according to claim 1, wherein the pyridine-based compound is pyridine-4-methanol, pyridine-N-oxide, pyridine-3-sulfonic acid, pyridine-2-carboxaldehyde, pyridine-3-carboxaldehyde, pyridine-3 -A composition for chemical mechanical polishing of a semiconductor wafer insulation layer, characterized in that a compound selected from the group consisting of carboxylic acid, pyridine-4-carboxylic acid is used.