CN1930664A - Polishing agent and polishing method - Google Patents

Abstract

To provide a polishing composition which has a high removal rate and enables to suppress occurrence of dishing and erosion, in polishing of a surface to be polished in the production of a semiconductor integrated circuit device. A chemical mechanical polishing composition for polishing a surface to be polished of semiconductor integrated circuit devices comprises (A) fine oxide particles, (B) pullulan, and (C) water. The polishing composition further contains (D) an oxidizing agent, and (E) a compound represented by the formula 1: wherein R is a hydrogen atom, a C 1-4 alkyl group, a C 1-4 alkoxy group or a carboxylic acid group.

Description

Abrasives and grinding methods

technical field

The present invention relates to abrasives used in the manufacturing process of semiconductor devices. In particular, it relates to an abrasive suitable for forming buried metal wiring using Cu-based metal as a wiring material and a tantalum-based metal as a barrier layer material, and a polishing method for a polished surface of a semiconductor integrated circuit device using the same.

Background technique

In recent years, along with the high integration and high functionality of semiconductor integrated circuits, the development of microfabrication technology that can achieve miniaturization and high density has been sought. In the semiconductor device manufacturing process, especially in the process of forming multilayer wiring, the planarization technology of the interlayer insulating film or buried wiring is very important. That is, due to the miniaturization and high density of the semiconductor manufacturing process, the multilayer wiring is formed, and the concavities and convexities on the surface of each layer tend to increase accordingly. High planarization technology in the multilayer wiring formation process is becoming more and more important.

As a wiring material, Cu has attracted attention because of its low specific resistance and excellent electromigration resistance compared with conventionally used Al alloys. Since the vapor pressure of the chloride gas of Cu is low, it is difficult to process into the wiring shape by the conventional reactive ion etching method (RIE: Reactive Ion Etching), so the embedded method is used for the formation of the wiring. In this method, recesses such as groove patterns or holes for wiring are formed in the insulating layer, and after forming a barrier layer, Cu is buried in the groove by sputtering or plating, and then excess Cu is deposited into the groove. The barrier layer and the barrier layer are removed by chemical mechanical polishing (CMP: Chemical Mechanical Polishing, hereinafter referred to as CMP) until the surface of the insulating layer other than the recess is exposed, so as to planarize the surface and form buried metal wiring. In recent years, the dual damascene method of simultaneously forming the Cu wiring in which Cu is embedded in the concave portion and the via hole portion has become mainstream.

To form such Cu buried wiring, in order to prevent Cu from diffusing into the insulating layer, a tantalum compound layer such as tantalum, tantalum alloy, or tantalum oxide is formed as a barrier layer. Therefore, it is necessary to remove the exposed barrier layer by CMP except for the wiring portion where Cu is buried. However, since the barrier layer is much harder than Cu, a sufficient polishing rate cannot often be obtained. Here, as shown in FIG. 1 , a two-stage polishing method comprising a first polishing step for removing an unnecessary wiring metal layer and a second polishing step for removing an unnecessary barrier layer has been proposed.

FIG. 1 is a cross-sectional view showing a method of forming buried wiring by CMP. (a) shows before polishing, (b) shows after the completion of the first polishing process for removing unnecessary wiring metal layer 4, (c) shows the process of second polishing process for removing unnecessary barrier layer 3, and (d) shows After the second grinding step is finished. First, grooves are formed in the insulating layer 2 as shown in FIG. 1( a ). This is a groove for forming buried wiring 6 in Si substrate 1 . A barrier layer 3 is formed thereon, and a wiring metal layer 4 (Cu film) is formed thereon, and excess wiring metal layer 4 is removed in a first polishing step. Next, the excess barrier layer 3 is removed in the second polishing step. Generally, after the first polishing step is completed, a loss of the wiring metal layer called a dimple 7 occurs. Therefore, in the second grinding process, it is necessary to completely remove the redundant barrier layer on the insulating layer as in (c), and at the same time, make the insulating layer become the same plane as the wiring metal layer as shown in (d), and reduce the The remaining depressions 7 achieve a high degree of planarization. In addition, when a material with a low dielectric constant is used for the insulating layer 2, a gap layer 5 may be formed between the insulating layer 2 and the barrier layer. In this case, the spacer layer may be left for planarization, or the spacer layer may be completely removed and polished until the low dielectric constant material is exposed. (d) shows the case where the remaining spacer layer is planarized.

In this way, planarization is performed by polishing, but in CMP using a conventional abrasive, there is a problem of increased dishing and abrasion of Cu embedded wiring 6 . Here, the dishing, as shown in FIG. 1(c) or 7 in FIG. 2, refers to a state in which the wiring metal layer 4 is excessively polished so that the central portion is sunken, and it is likely to occur in a wide wiring portion. Erosion is a phenomenon that tends to occur in fine wiring parts or dense wiring parts, that is, a phenomenon in which, as shown in FIG. The insulating layer 2, the phenomenon that the insulating layer 2 is partially thinned. That is, the abrasive portion 8 that is excessively ground compared with the polished portion 10 of the Global portion is generated. In addition, the barrier layer 3 is omitted in FIG. 2 .

When a conventional abrasive is used, since the polishing rate of the barrier layer 3 is lower than that of the wiring metal layer 4, Cu in the wiring portion is excessively polished during the removal of the barrier layer 3, resulting in large depressions. In addition, the polishing pressure applied to the barrier layer 3 and the underlying insulating layer 2 of the high-density wiring portion is relatively larger than that of the low-wiring density portion. Therefore, depending on the wiring density, the degree of polishing in the second polishing step also greatly differs, and as a result, the insulating layer 2 of the high-density wiring portion is excessively polished, resulting in large abrasion. If denting or abrasion occurs, an increase in wiring resistance or electromigration tends to occur, and there is a problem that the reliability of the device decreases.

Tantalum or a tantalum compound used as a barrier layer is difficult to chemically etch, and since it is harder than Cu, it is difficult to remove by mechanical polishing. If the hardness of the abrasive grains is increased in order to increase the grinding speed, scratches will be formed on the soft Cu wiring, and problems such as electrical failures will easily occur. In addition, if the concentration of abrasive grains in the abrasive is increased, it is difficult to maintain the dispersed state of the abrasive grains in the abrasive, and problems in dispersion stability such as sedimentation over time or gelation tend to occur.

In addition, in CMP, it is necessary to prevent abrasion of Cu during polishing. Among the corrosion inhibitors for Cu and copper alloys, benzotriazole (hereinafter referred to as BTA) and its derivatives are known as the most effective and widely used (for example, refer to "Benzotriazole Inhibitors" Erosion Inhibition Mechanism and Its Application" (Takeki Notoya, Japan Antirust Technology Association, 1986, P.1)). The BTA forms a dense protective film on the surface of Cu and copper alloys, inhibits oxidation-reduction reactions, and prevents abrasion. Therefore, it is effective as an additive for preventing sinking of the Cu wiring portion. BTA or its derivatives are contained in the abrasive to form a protective film on the surface of Cu to prevent dishing. (For example, refer to USP 5,770,095). However, if only the amount of BTA added is increased, the Cu polishing rate will decrease and the polishing time will increase. Therefore, there is a problem that pitting and abrasion defects will increase.

Conventionally, water-soluble polymers have also been studied as one of Cu protective film forming agents for suppressing dishing. All of them are abrasives having a large polishing rate ratio of the metal to the barrier layer (metal/barrier layer) and a large polishing rate ratio of the metal to the insulating layer (metal/insulating layer). That is, it aims at suppressing the polishing of the barrier layer and the insulating layer while removing Cu by high-speed polishing. (For example, refer to Japanese Patent Laid-Open No. 2001-144047, Japanese Patent Laid-Open No. 2001-144048, Japanese Patent Laid-Open No. 2001-144049, Japanese Patent Laid-Open No. 2001-1440451, Japanese Patent Laid-Open No. 2003- Bulletin No. 188120)

In addition, water-soluble polymers have also been studied in the abrasives used in the multilayer wiring manufacturing process using low dielectric constant insulating layers and copper wiring for the purpose of suppressing signal delay developed in recent years (for example, refer to Japanese Patent No. Publication No. 2003-68683).

However, these studies are all related to the first polishing step of removing Cu by polishing. That is, in the second polishing step of polishing the barrier layer at a high speed, polishing Cu at a moderate polishing speed, and achieving a high degree of planarization while reducing the insulating layer, no effective abrasive has been found so far.

This is because following reason, promptly, to the polishing agent of the 1st polishing step, mainly request to polish wiring metal with high polishing rate, on the other hand, to the polishing agent of the 2nd polishing step, require to polish barrier layer, The insulating layer is polished at a higher polishing rate than the wiring metal, and the required characteristics of the two are quite different.

As described above, the role of the second polishing step in CMP is to completely remove the excess barrier layer portion while reducing dishing produced in the first polishing step. In FIG. 1, when the size of the depression formed in the first polishing step is thinner than the film thickness of the barrier layer, only the barrier layer can be removed to remove the depression in the second polishing step, and polishing of the wiring metal or the insulating layer may not be necessary. However, the thickness of the barrier layer is small, typically 20 to 40 nm, and Cu is removed by high-speed polishing in the first polishing step, so it is extremely difficult to suppress dishing within a range thinner than the thickness of the barrier layer. In addition, in the first polishing step, when there is a difference in the Cu polishing rate, superpolishing for completely removing excess Cu residues in the surface is required, so it is more difficult to reduce dishing.

Therefore, in the second polishing step, it is required to repair the recesses larger than the thickness of the barrier layer, and to achieve a high level of planarization, the recesses formed in the first polishing step. In addition, generally as shown in FIG. 2, in ultra-fine wiring or high-density wiring, the insulating layer 2 of the wiring part is more polished than the insulating layer part (Global part) without a wiring pattern, and the insulating layer 2 is easily deformed. Thin. In recent years, reduction of this abrasion has become a major issue due to advancements in semiconductors and miniaturization of wiring portions.

disclosure of invention

Here, the object of the present invention is to provide a kind of polishing agent, in the polishing of the surface to be polished in the manufacture of semiconductor integrated circuit device, by having a high polishing rate, suppressing the preferential polishing of recessed parts and giving priority to polishing of convex parts, it can A buried wiring portion with high reliability and excellent electrical characteristics is formed. More specifically, an object of the present invention is to provide a polishing agent which has a high barrier layer polishing speed and can suppress dishing or Abrasion occurs, and can form a buried wiring part with less scratches, high reliability, and excellent electrical characteristics. It is formed from a slurry in which abrasive particles are dispersed, and the abrasive is difficult to precipitate or gel over time. , is a very stable abrasive. Other objects and advantages of the present invention are illustrated by the following description.

The 1st aspect of the present invention provides a kind of abrasive, and this abrasive is in the manufacture of semiconductor integrated circuit device, is used for the chemical mechanical polishing abrasive of grinding surface to be polished, wherein contains (A) oxide particle, ( B) Pullulan and (C) water.

A 2nd aspect provides the abrasive as described in the 1st aspect, wherein it also contains (D) an oxidizing agent, (E) a compound represented by formula (1) (wherein, R is a hydrogen atom, and the number of carbon atoms is 1 to 4 The alkyl group, the number of carbon atoms is

1 to 4 alkoxy or carboxyl).

A third aspect provides the polishing agent according to the first or second aspect, wherein the weight average molecular weight of the component (B) is within the range of 10,000 to 1,000,000.

A 4th aspect provides the abrasive as described in the 1st, 2nd or 3rd aspect, wherein, component (A) is selected from silicon dioxide, aluminum oxide, cerium oxide, zirconium oxide, titanium oxide, tin oxide, zinc oxide and one or more materials of manganese oxide.

A fifth aspect provides the abrasive according to any one of the first to fourth aspects, wherein the component (A) is silica fine particles.

A 6th aspect provides the abrasive as described in any one of the 1st to 5th aspects, wherein, with respect to the total mass of the abrasive, the content of the component (A) is in the range of 0.1 to 20% by mass, and the component ( The content of B) is 0.005-20 mass %, and the content of component (C) exists in the range of 40-98 mass %.

A 7th aspect provides the abrasive as described in any one of the 2nd to 6th aspects, wherein, relative to the total mass of the abrasive, the content of the component (D) is in the range of 0.01 to 50% by mass, and the component ( The content of E) is within the range of 0.001 to 5% by mass.

An eighth aspect provides the abrasive according to any one of the first to seventh aspects, wherein the abrasive is used for polishing a surface to be polished on which a wiring metal layer, a barrier layer, and an insulating layer are formed.

A ninth aspect provides the abrasive according to the eighth aspect, wherein the wiring metal layer is formed of copper, and the barrier layer is formed of one or more materials selected from tantalum, a tantalum alloy, and a tantalum compound.

A tenth aspect provides a method for polishing a surface to be polished of a semiconductor integrated circuit device, the method comprising: supplying a polishing agent to a polishing pad, bringing the surface to be polished into contact with the polishing pad, and polishing the surface to be polished by relative motion between the two. A polishing method for polishing a surface, wherein the polishing agent described in any one of aspects 1 to 9 is used in the polishing step after the barrier layer is formed to polish the wiring metal layer.

According to the present invention, in the polishing of the surface to be polished in the manufacture of a semiconductor integrated circuit device, by having a high polishing rate, suppressing the preferential polishing of the concave portion, and preferential polishing of the convex portion, the occurrence of dents or abrasion can be suppressed, and the formation of scratches is less , Embedded wiring part with high reliability and excellent electrical characteristics. The dispersion stability of the abrasive grains of this abrasive is also excellent.

A brief description of the drawings

[ Fig. 1 ] is a schematic cross-sectional view of a semiconductor integrated circuit device in a process showing a method of forming a buried wiring by CMP.

[ Fig. 2 ] is a schematic cross-sectional view of a semiconductor integrated circuit device for explaining definitions of dishing and erosion.

Explanation of symbols

1 Si substrate

2 insulating layer

3 barrier layer

4 wiring metal layer

5 spacers

6 Embedded wiring

7 concave part

8 Abrasive part

9 Maximum height difference

10 Grinding part of spherical part

The best way to practice the invention

Hereinafter, embodiments of the present invention will be described using figures, tables, formulas, examples, and the like. In addition, these figures, tables, formulas, examples, and descriptions are merely examples of the present invention, and do not limit the scope of the present invention. Other implementations as long as they conform to the inventive concept of the present invention also belong to the scope of the present invention.

The abrasive used in the present invention is a chemical-mechanical abrasive for grinding a surface to be polished in the manufacture of a semiconductor integrated circuit device, wherein it contains (A) oxide particles, (B) pullulan and (C )water. In addition, it is preferable to further contain (D) an oxidizing agent and (E) a compound represented by formula (1) (wherein, R is a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, an alkyl group with 1 to 4 carbon atoms alkoxy or carboxyl).

If these abrasives are used, in the manufacturing process of the semiconductor integrated circuit device, the surface thereof is polished,

It is easy to form a layer having a flat surface formed of an insulating layer or the like. More specifically, a high polishing rate can be realized, and the occurrence of dishing or abrasion can be suppressed by suppressing preferential polishing of concave portions while preferentially polishing convex portions. In addition, it is possible to form a buried wiring portion with less scratches, high reliability, and excellent electrical characteristics. The dispersion stability of the abrasive grains of this abrasive is also excellent.

The present invention is particularly useful for a polished surface of a semiconductor integrated circuit device in which a wiring metal layer, a barrier layer, and an insulating layer are formed. In addition, in the present invention, the "surface to be polished" refers to a surface at an intermediate stage in the process of manufacturing a semiconductor integrated circuit device. Therefore, there may be no surface where the wiring metal layer, the barrier layer, and the insulating layer coexist.

In the abrasive, the component (A) oxide fine particles are abrasive grains. Specifically, it is preferably at least one selected from the group consisting of silica, alumina, ceria, zirconia, titania, tin oxide, zinc oxide, germanium oxide, and manganese oxide. As silica, silica produced by various known methods can be used. For example, fumed silica synthesized by silicon tetrachloride in the gas phase in the flame of oxygen and hydrogen, colloidal silica formed by ion exchange of sodium silicate, or colloidal silica formed by hydrolyzing alkoxy silicon in liquid phase Silica particles such as silica.

Also, colloidal alumina is preferably used. Alternatively, cerium oxide, zirconium oxide, titanium oxide, tin oxide or zinc oxide produced by a liquid phase method or a gas phase method is preferably used. Among them, it is preferable to use colloidal silica that can obtain a high-purity product with a uniform particle diameter.

The average particle diameter of the component (A) is preferably from 5 to 500 nm, more preferably from 10 to 300 nm, from the viewpoint of grinding properties and dispersion stability. In addition, it is preferable to appropriately select the concentration of component (A) in the abrasive within the range of 0.1 to 20% by mass of the total mass of the abrasive in consideration of the polishing speed, uniformity, material selectivity, and dispersion stability. The above-mentioned concentration is more preferably in the range of 1 to 15% by mass of the total mass of the abrasive.

Component (B) is used to accelerate the polishing rate of the insulating layer. In general, when silicon dioxide is used for the insulating layer, the polishing speed of the portion (spherical portion) that is not patterned in the patterned wafer is significantly lower than the polishing speed of the blanket wafer (blanket wafer) that is not patterned. slowing trend. On the other hand, since the contact area between the insulating layer and the abrasive in the patterned portion is large, the polishing rate tends to be increased. Therefore, even in the same wafer, the polishing speeds of the insulating layer of the spherical portion and the wiring portion are greatly different, which leads to the expansion of abrasion in the second polishing step. As the width of the wiring becomes narrower with the progress of the times, this tendency becomes more and more prominent, so it is difficult to suppress abrasion in the thin line part.

In this case, adding the component (B) suppresses the concavity from being preferentially polished while giving priority to the convexity, thereby promoting the polishing of the spherical portion, thereby achieving flattening and reducing abrasion. The reason for this is not clear, but it is considered that the polishing rate is increased over a wide area because the hydroxyl groups on the surface of the abrasive grains interact with the hydroxyl groups on the component (B) and the hydroxyl groups on the surface of the insulating layer. Therefore, it is considered that if the abrasive grains are oxides and the surface to be polished is an oxide film, the interaction will work. When the abrasive grains are silica and the surface to be polished contains silica as the main component, the interaction mediated by the component (B) further contributes to the planarization characteristics.

Pullulan is a polysaccharide composed of three molecules of glucose α-1,4 combined with maltotriose, and then α-1,6 combined. When the weight-average molecular weight of the component (B) is in the range of 10,000 to 1,000,000, the effect is high. The presence of hydroxyl groups is considered to be an important factor. If the weight-average molecular weight is less than 10,000, the effect of increasing the polishing rate will decrease, and even if it exceeds 1 million, the effect will not increase significantly. Especially preferably in the range of 50,000 to 300,000. In addition, the weight average molecular weight can be measured by gel permeation chromatography (GPC).

From the point of view of obtaining a sufficient grinding-promoting effect, the concentration of the component (B) in the abrasive is within the range of 0.005 to 20% by mass, preferably in consideration of the grinding speed, the uniformity of the abrasive slurry, etc. Certainly.

Component (C) is a solvent for dispersing oxide fine particles and dissolving reagents. Pure water or deionized water is preferred. Since water has a function of controlling the fluidity of the present polishing agent, its content can be appropriately set according to the desired polishing characteristics such as polishing speed and flattening characteristics. It is preferable to contain 40-98 mass % in this abrasive. It is particularly preferably in the range of 60 to 90% by mass.

Component (D) is used to form an oxide film on the surface of the barrier layer, and remove the oxide film from the surface to be polished by mechanical force to promote polishing of the barrier layer.

As component (D), it is preferably a One or more types of salt. As iodate, periodate, hypochlorite, perchlorate, persulfate, percarbonate, perborate, and superphosphate, alkali metal salts such as ammonium salt and potassium salt can be used. Among them, it is preferable to use hydrogen peroxide which does not contain an alkali metal component and does not form harmful by-products.

Considering from the effect of obtaining sufficient grinding acceleration, the concentration of the component (D) in the abrasive is preferably in the range of 0.01 to 50% by mass in the abrasive, and considering the grinding speed, the uniformity of the abrasive slurry, etc. Set appropriately. More preferably, it exists in the range of 0.5-5 mass %.

Component (E) has a function of forming a protective film on the wiring metal surface in order to prevent sinking of the wiring metal portion. When the wiring metal is made of Cu, it is only necessary to form a protective film on the surface of Cu by physical adsorption or chemical adsorption to suppress the elution of Cu. In formula (1), R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a carboxyl group.

Specifically, for example, BTA, tolutriazole (TTA) in which one H atom in the 4 or 5 position of the benzene ring of BTA is substituted with a methyl group, benzotriazole-4-carboxylic acid substituted with a carboxyl group, etc. . These compounds may be used alone or in combination of two or more. From the viewpoint of polishing properties, the abrasive contains the component (E) preferably in an amount of 0.001 to 5% by mass, more preferably in a range of 0.01 to 0.5% by mass.

In this abrasive, it is preferable to contain an acid in addition to components (A) to (C) or components (A) to (E). The acid is preferably at least one selected from nitric acid, sulfuric acid, and carboxylic acid. Among them, an oxyacid having an oxidizing ability, or nitric acid not containing a halogen is preferred. In addition, the concentration of the acid in the grinding agent is preferably Within the range of 0.01 to 20% by mass. By adding acid, the polishing rate of the barrier layer or insulating film can be increased. In addition, the dispersion stability of the present abrasive can also be improved.

In addition, in order to adjust the present abrasive to a predetermined pH, a basic compound may be added to the present abrasive at the same time as the acid is added. As the basic compound, ammonia, potassium hydroxide, or a quaternary ammonium base such as tetramethylammonium hydroxide or tetraethylamine hydroxide (hereinafter referred to as TEAH), or the like can be used. When it is preferable not to contain an alkali metal, ammonia is preferable. In addition, when components (A) to (C) or components (A) to (E) are treated with acids or basic compounds and then used as abrasive components, the above-mentioned acids or bases are also appropriately added. Sexual compounds.

The pH of this abrasive can be used within a wide range of 2-10. Considering the grinding properties and dispersion stability of the abrasive, when silica is used for the oxide particles, the pH is preferably less than or equal to 5 or greater than or equal to 7, and the desired grinding speed of the corresponding wiring metal (such as Cu) can be obtained at Use in acidic range (pH2-5) and neutral range/alkaline range (pH7-10).

When the oxide fine particles are alumina or ceria, the pH is adjusted to be optimal in consideration of their isoelectric point and gelation range. Thus pH buffering agents may also be used. As the pH buffering agent, any substance can be used as long as it has a general pH buffering ability, but it is preferably selected from succinic acid, citric acid, oxalic acid, phthalic acid, tartaric acid, and adipic acid as polycarboxylic acids. One or more acids. Alternatively, glycylglycine or alkali metal carbonates may be used. In addition, the concentration of the pH buffering agent in the abrasive is preferably from 0.01 to 10% by mass of the total mass of the abrasive.

The abrasive according to the present invention does not necessarily have to be prepared by mixing all the abrasive materials to be used for grinding. It is also possible to mix the grinding materials to form the composition of the grinding agent when it is used for grinding.

This abrasive is suitable for polishing and planarizing the surface to be polished of a semiconductor integrated circuit device on which an insulating layer is formed. Since this polishing agent can also control the polishing speed of wiring metal (such as Cu), it is also more suitable for polishing the surface to be polished on which the wiring metal layer, barrier layer and insulating layer are formed. In this case, especially when the barrier layer is formed of one or more layers selected from tantalum, tantalum alloys, and tantalum compounds, a high effect can be obtained. However, it is also applicable to films made of other metals, and a sufficient effect can be obtained when a film made of metals or metal compounds other than tantalum, such as Ti, TiN, TiSiN, WN, etc., is used as a barrier layer.

That is, this abrasive has both functions of high-speed polishing of the barrier layer and planarization of the insulating layer. When only the latter function is used, it can also be effectively used in a so-called planarization process of an interlayer insulating layer, a formation process of a shallow trench isolation (STI), and the like.

In addition, this abrasive can be highly effective when the wiring metal layer is selected from one or more of Cu, copper alloy, and copper compound, but for metals other than Cu, such as Al, W, Ag, Pt, Au and other metal films Also applicable.

In addition, a silicon oxide film is known as the insulating layer. Such a silicon oxide film is generally formed by depositing tetraethoxysilane (TEOS) by CVD.

In addition, in recent years, in order to suppress signal delay, an insulating layer with a low dielectric constant is used instead of such a _SiO2 film more and more. As this material, in addition to a film formed of fluorine-added silicon oxide (SiOF), organic SOG (a film containing an organic component obtained by spin on glass), and a low dielectric constant material such as porous silicon dioxide, there are also known SiOC film formed by CVD method (chemical vapor phase method).

The SiOC film formed by the CVD method has developed conventional technology as a process technology, and can achieve a technology suitable for mass production in a wide range by appropriate process adjustment. Therefore, a technique for planarizing a film using this insulating layer is required.

As the silicone material of the low dielectric constant material, for example, trade name: Black Diamond (dielectric constant 2.7, technology of Applaid Materials Co., Ltd.), trade name Coral (dielectric constant 2.7, technology of Novellus Systems Co., Ltd.), Aurora2.7 (dielectric constant of 2.7, Japan ASM company technology) and so on. It is particularly preferred to use compounds having Si—CH ₃ bonds.

The abrasive according to the present invention can be suitably used in the case of employing these various insulating layers.

In addition, in recent years, when a low dielectric constant film of a silicone material is used, it has become mainstream to form a spacer layer thereon. The purpose of the spacer layer is to improve the adhesion between the barrier layer and the organic silicon material and to improve the abrasive properties of the organic silicon material. A silicon oxide film used as a spacer layer is generally formed of a cross-linked structure of Si and O, and the atomic ratio of Si and O is 1:2. However, a film containing atoms such as N and C may also contain Si ₃ N ₄ , SiC, etc. as subcomponents. The abrasive of the present invention can also be used well when such a spacer layer is used.

The polishing agent of the present invention is suitable for a polishing method in which the polishing agent is supplied to a polishing pad, brought into contact with a surface to be polished, and the surface to be polished and the polishing pad are relatively moved to perform polishing. If necessary, the pad conditioner may be brought into contact with the surface of the polishing pad to perform polishing while adjusting the surface of the polishing pad.

This abrasive is suitable for a method of forming a recess such as a groove pattern or a hole for wiring in an insulating layer on a substrate, and then forming a barrier layer, and then depositing, for example, Cu into a film by sputtering or plating. When the surface to be polished is formed by burying in the groove, Cu and the barrier layer are removed by CMP until the surface of the insulating layer other than the recess is exposed, thereby forming a buried metal wiring.

In the two-stage polishing process shown in FIG. 1 , the polishing agent according to the present invention can be used in any stage of polishing. In particular, if it is used in the second polishing step from the state of FIG. 1(b) to the state of FIG. 1(d) in the polishing stage after the barrier layer is developed, it is difficult to form pits or erosion, so it is suitable.

Example

Hereinafter, the present invention will be more specifically described by way of examples (Examples 1-3, 8-12) and comparative examples (Examples 4-7).

(1) Preparation of abrasive

Each abrasive of Examples 1 to 7 was prepared as follows. Add acid and basic compounds and pH buffering agent to water, stir for 10 minutes to obtain liquid a. Next, component (E) was dissolved in ethylene glycol until the concentration of solid content was 40% by mass, and this was added to liquid a, and then component (B) was added and stirred for 10 minutes to obtain liquid b.

Next, after gradually adding the aqueous dispersion of the component (A) to the liquid b, a basic compound was gradually added to adjust the pH to 3. Furthermore, the aqueous solution of the component (D) was added, and it stirred for 30 minutes, and the abrasive was obtained. The types of components (B), components (E) and components (A) used in each example and their concentrations (mass %) with respect to the total mass of the abrasive are shown in Table 1, respectively. The components (D), acid , alkaline compound and the kind of pH buffering agent and their concentration relative to the total mass of abrasive are shown in Table 2 respectively. Pure water was used as water. In addition, in the comparative example, the material in Table 1 was used instead of component (B).

(2) Grinding conditions

Grinding was performed with the following equipment and under the following conditions.

Grinder: Fully automatic CMP device MIRRA (manufactured by APPLIED MATERIALS)

Grinding pressure: 14kPa

Number of rotations: platen (platform) 123rpm, polishing head (substrate holding part) 117rpm

Abrasive supply speed: 200mL/min

Polishing pad: IC1000 (manufactured by Rodel Corporation).

(3) Grinding object

Use the wafer below.

(3-1) Cladding wafer

(a) Cu (wiring metal layer) polishing rate evaluation wafer

An 8-inch wafer having a Cu layer having a thickness of 1500 nm formed on a substrate by plating was used.

(b) Wafer for evaluation of polishing rate of tantalum (barrier layer)

An 8-inch wafer having a tantalum layer formed to a thickness of 200 nm on a substrate by sputtering was used.

(c) Wafer for evaluation of polishing rate of SiO ₂ (insulating layer)

An 8-inch wafer with an 800-nm-thick _SiO2 layer formed on a substrate by plasma CVD was used.

(d) SiOC (low dielectric constant insulating layer) wafer for polishing speed evaluation

An 8-inch wafer having a SiOC layer formed on a substrate with a thickness of 800 nm by plasma CVD was used.

(3-2) Pattern wafer

Using an 8-inch wafer (trade name: 831BDM000, manufactured by SEMATECH), a wiring pattern with a wiring width of 5 μm to 100 μm is formed at a wiring density of 50% with respect to the insulating layer formed on the board, and the wiring pattern is formed on the substrate. A tantalum layer with a thickness of 25 nm was formed on the insulating layer by sputtering, and a Cu layer with a thickness of 1500 nm was formed thereon by plating.

(4) Evaluation method of abrasive properties

The polishing rate was calculated from the film thickness before and after polishing. For the measurement of the film thickness, a sheet resistance measuring device RS75 (manufactured by KLA Tencor Co., Ltd.) calculated from the surface resistance obtained by the four-probe method was used for Cu and tantalum, and an optical interference type fully automatic film thickness was used for the insulating layer. The measuring device UV1280SE (manufactured by KLA Tencor Co., Ltd.). For the evaluation of the flattening characteristics of dishing and abrasion, a high-resolution sea bottom topographic precision measuring instrument (Profaira) HRP100 (manufactured by KLA Tencor Co., Ltd.), which measures a height difference by a stylus type, was used.

(5) Evaluation of cladding wafer polishing characteristics

The respective polishing rates of the wiring metal layer, the barrier layer, and the insulating layer were evaluated, and each of the above-mentioned clad wafers was used. In this evaluation, abrasives having the compositions of the above examples were used.

Table 3 shows the polishing rates (in nm/min) of Cu, tantalum, SiO ₂ , and SiOC films obtained using clad wafers. From this result, it can be seen that the polishing rate of tantalum is high and the polishing rate of Cu is relatively small in the polishing agent according to the present invention. By utilizing such properties, it can be seen that a polishing agent suitable for polishing in the second polishing step is obtained. In the second polishing step, it is required to polish the barrier layer at a high polishing rate and polish the insulating layer at a higher speed than that of the wiring metal.

(6) Evaluation of pattern grinding characteristics

A patterned wafer was used for the evaluation of dishing and erosion. The pattern wafer was polished using a two-stage polishing method consisting of a first polishing step for removing the wiring metal layer and a second polishing step for removing the barrier layer. The abrasive used in the first polishing step uses an abrasive having a composition such that alumina, hydrogen peroxide, citric acid, ammonium polyacrylate, and water are 3% by mass and 4% by mass, respectively, based on the total mass of the abrasive. , 0.1% by mass, 0.05% by mass, and 92.85% by mass. In the second polishing step, polishing agents having the compositions of the above examples were used.

For each example, in order to evaluate the ability of the polishing agent to eliminate the level difference of the insulating layer, a pattern wafer was prepared in which excess tantalum was completely removed in the first polishing step. In this level difference, since the dishing at the position where the wiring width is 5 μm is 10 nm, and the abrasion is 50 nm, the maximum level difference (corresponding to the portion indicated by 9 in FIG. 2 ) is 60 nm.

By performing the second polishing step, the insulating layer of the wafer was removed for 60 seconds, and the extent to which the maximum level difference in the wiring was eliminated was measured. The initial maximum height difference - the value obtained from the maximum height difference after grinding is used as the degree of height difference elimination (unit: nm). From the results in Table 4, it can be seen that the abrasives of the examples are effective in eliminating the level difference.

The dispersion stability of the abrasive was evaluated by observing changes in the average particle diameter immediately after preparation and one week after preparation. The average particle diameter was measured by microtrack UPA (manufactured by Nikkiso Co., Ltd.). An increase in the average particle diameter within 50% was rated as ◯ (good), and a larger one or gelling was rated as × (poor).

In addition, with the grinding agent of Example 1 as a benchmark, for the examples of the type of abrasive grains of the conversion component (A) (Example 8, 9), the example of the molecular weight of pullulan of the conversion component (B) (Example 10) and the BTA is changed to TTA, and the example (Example 11, 12) that maintains its low amount can also be prepared according to the composition shown in Table 1, 2, and Example 1-7 is the same as the preparation of polishing solution. The obtained polishing liquids (Examples 8-12) were evaluated similarly to Examples 1-7, and the results shown in Tables 3 and 4 were obtained.

In Examples 11 and 12, as shown in Table 3, the polishing speed of tantalum, SiO ₂ , and SiOC is high, while that of Cu is small. As shown in Table 4, the level difference is eliminated to a large extent.

In addition, as a result of microscopic observation, no scratches were generated in the Cu wiring of the example.

Table 1 Mw: Weight average molecular weight example ingredient (A) Ingredient (B) or substitute ingredient (E) Substance name Concentration (mass%) Substance name Concentration (mass%) Substance name Concentration (mass%) 1 silica 6 Pullulan (Mw: 200000) 0.05 BTA 1 2 silica 6 Pullulan (Mw: 200000) 0.1 BTA 1 3 silica 6 Pullulan (Mw: 200000) 1 BTA 1 4 silica 6 Polyvinyl alcohol (Mw: 24000) 0.1 BTA 1 5 silica 6 Trehalose 0.1 BTA 1 6 silica 6 Polyvinylpyrrolidone (Mw: 9000) 0.1 BTA 1 7 silica 6 none none BTA 1 8 Aluminum oxide 1 Pullulan (Mw: 200000) 0.05 TTA 1 9 Ceria 1 Pullulan (Mw: 200000) 0.05 TTA 1 10 silica 6 Pullulan (Mw: 100000) 0.1 BTA 1 11 silica 6 Pullulan (Mw: 200000) 0.05 TTA 0.5 12 silica 6 Pullulan (Mw: 200000) 0.05 TTA 0.2

Table 2 example ingredient (D) acid basic compound pH buffer Substance name Concentration (mass%) Substance name Concentration (mass%) Substance name Concentration (mass%) Substance name Concentration (mass%) 1 hydrogen peroxide 1 nitric acid 0.6 KOH 0.6 citric acid 0.2 2 hydrogen peroxide 1 nitric acid 0.6 KOH 0.6 citric acid 0.2 3 hydrogen peroxide 1 nitric acid 0.6 KOH 0.6 citric acid 0.2 4 hydrogen peroxide 1 nitric acid 0.6 KOH 0.6 citric acid 0.2 5 hydrogen peroxide 1 nitric acid 0.6 KOH 0.6 citric acid 0.2 6 hydrogen peroxide 1 nitric acid 0.6 KOH 0.6 citric acid 0.2 7 hydrogen peroxide 1 nitric acid 0.6 KOH 0.6 citric acid 0.2 8 hydrogen peroxide 3 nitric acid 0.1 ammonia 0.1 tartaric acid 0.1 9 hydrogen peroxide 0 nitric acid 0.1 ammonia 0.1 Succinic acid 0.1 10 hydrogen peroxide 1 nitric acid 0.6 KOH 0.6 citric acid 0.2 11 hydrogen peroxide 0.5 nitric acid 0.6 KOH 0.6 citric acid 0.2 12 hydrogen peroxide 0.2 nitric acid 0.6 KOH 0.6 citric acid 0.2

table 3 example Cu grinding speed (nm/min) Ta grinding speed (nm/min) SiO ₂ grinding speed (nm/min) SiO ₂ grinding speed (nm/min) 1 50 90 120 60 2 50 90 120 60 3 50 90 120 60 4 70 70 80 40 5 60 80 50 20 6 - - - - 7 40 100 100 60 8 40 100 100 60 9 40 100 100 60 10 50 90 120 60 11 40 120 80 80 12 40 100 80 80

Table 4 example The degree of height difference elimination (nm) dispersion stability 1 40 ○ 2 40 ○ 3 40 ○ 4 10 ○ 5 10 ○ 6 - x 7 5 ○ 8 35 ○ 9 35 ○ 10 35 ○ 11 40 ○ 12 40 ○

In addition, Japanese Patent Application No. 2004-063366 (applied to Japan Patent Office on March 8, 2004) and Japanese Patent Application No. 2004-305238 (applied to The contents of the entire specification of the application filed by the Japan Patent Office shall be regarded as the disclosure content of the specification of the present invention.

Claims (10)

1. grinding agent, it is the cmp grinding agent that is used to grind in the manufacturing of conductor integrated circuit device by abradant surface, it is characterized in that, contains (A) oxide fine particle, (B) pulullan polysaccharide and (C) water.

2. grinding agent as claimed in claim 1 is characterized in that, also contains (D) oxidant and (E) compound shown in the formula (1),

Wherein, R is the alkyl of hydrogen atom, carbon number 1～4, the alkoxyl or the carboxyl of carbon number 1～4.

3. grinding agent as claimed in claim 1 or 2 is characterized in that, the weight average molecular weight of composition (B) is in 10,000～1,000,000 scope.

4. as each described grinding agent in the claim 1～3, it is characterized in that composition (A) is formed by the material more than a kind that is selected from silicon dioxide, aluminium oxide, cerium oxide, zirconia, titanium oxide, tin oxide, zinc oxide and manganese oxide.

5. as each described grinding agent in the claim 1～4, it is characterized in that composition (A) is a silicon dioxide microparticle.

6. as each described grinding agent in the claim 1～5, it is characterized in that, gross mass with respect to grinding agent, the amount of composition (A) is in the scope of 0.1～20 quality %, the amount of composition (B) is at 0.005～20 quality %, and the amount of composition (C) is in the scope of 40～98 quality %.

7. as each described grinding agent in the claim 2～6, it is characterized in that with respect to the gross mass of grinding agent, the amount of composition (D) is in the scope of 0.01～50 quality %, the amount of composition (E) is in the scope of 0.001～5 quality %.

8. as each described grinding agent in the claim 1～7, it is characterized in that, it be used to grind be formed with wiring metal layer, barrier layer and insulating barrier by the grinding agent of abradant surface.

9. grinding agent as claimed in claim 8 is characterized in that the wiring metal layer is formed by copper, and the barrier layer is formed by the material more than a kind that is selected from tantalum, tantalum alloy and tantalum compound.

10. by the Ginding process of abradant surface, it is to supply with grinding agent to grinding pad, make by abradant surface and contact with grinding pad, by relative motion between the two grind by the Ginding process of abradant surface, it is characterized in that, grind the wiring metal level, in the grinding stage after manifesting the barrier layer, use each described grinding agent in the claim 1～9.

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