KR20080093963A - Capping layer formation onto a dual damescene interconnect - Google Patents

Abstract

A process for the formation of a capping layer on a conducting interconnect for a semiconductor device is provided, the process comprising the steps of: (a)providing one or more conductors in a dielectric layer, and (b) depositing a capping layer on an upper surface of at least some of the one or more conductors, characterised in that the process further includes: (c) the step of, prior to depositing the capping layer, reacting the dielectric layer with an organic compound in a liquid phase, the said organic compound having the following general formula: (I) where X is a functional group, R is an organic group or a organosiloxane group, Y1 is either a functional group or an organic group or organosiloxane group, and Y2 is either a functional group or an organic group or organosiloxane group, and where the functional group(s) is / are independently selected from the following: NH2, a secondary amine, a tertiary amine, acetamide, trifluoroacetamide, imidazole, urea, OH, an alkyoxy, acryloxy, acetate, SH, an alkylthiol, sulfonate, methanosulfonate, and cyanide, and salts thereof.

Description

CAPPING LAYER FORMATION ONTO A DUAL DAMESCENE INTERCONNECT}

The present invention relates to a method of depositing a capping layer on a conductive interconnect in a dielectric layer in a semiconductor device. More specifically, the present invention relates to a method of treating a dielectric layer before deposition of a capping layer.

Semiconductor manufacturers have continually researched to produce faster and more complex integrated circuits. One way to accomplish this is to reduce the size of the semiconductor circuit to reduce the gate (transistor) delay. However, as the size of the circuit is reduced, the physical properties of the materials making up the circuit have become increasingly important. In particular, as the size of the conductive interconnects included in the circuit and more particularly their widths are reduced, the electrical resistance of the interconnects increases accordingly. This causes an increased interconnect time delay. Until recently, aluminum has traditionally been used to make such interconnects. However, to solve the problem associated with the reduction in circuit size, semiconductor manufacturers have found that copper, compared to aluminum in use with interconnects, provides better material properties due to its lower bulk resistance, higher thermal conductivity, and higher melting point, It has thus been found that this results in improved speed and reliability. In addition, copper also has a lower rate of grain boundary diffusion, and thus more electrophoretic resistance.

 Copper interconnects have a problem with themselves. Copper interconnects still tend to degrade by diffusion and electrophoresis. Passivated dielectric layers, typically having a thickness of 30 to 50 nanometers, are generally applied to the exposed top surface of the copper interconnect. An example of such a dielectric used in this role is SiCN. However, copper has poor adhesion to the dielectric and therefore has a dielectric / copper interface, one of the major limiting factors in the reliability of the final semiconductor device. In addition, since dielectrics such as SiCN have high dielectric constants (k values), their presence adds k values of the dielectric stack of the final semiconductor device. This is also undesirable.

To address this problem, a thin capping layer comprising a metal, typically a metal alloy, may be deposited on the copper interconnect instead of a more conventional dielectric such as SiCN. The capping layer is also known as the passivation layer.

Although the problems of inferior adhesion and electrophoresis are described in relation to copper, it will be appreciated that interconnects made from other materials having the same problem may also benefit from such capping layers for the same reasons.

Techniques used to deposit a capping layer comprising metal on the interconnect, such as electroless deposition, are generally selective in nature in that they deposit a capping layer on the interconnect but not on the dielectric surface. However, the selectivity and efficiency of this technique are limited because of the presence of defects on the dielectric surface. These defects can form bridges between two neighboring interconnects during deposition of the capping layer, resulting in unwanted electron exchange between the interconnects, shorting the device and ultimately causing device failure. Such defects include defects inherent in the dielectric surface. An example of an inherent defect is a fine scratch on a surface, which can initiate the deposition of a capping material on a dielectric surface. In addition, small areas of residues of metals or metal oxides on the surface may also be considered inherent defects. Such regions can be derived, for example, from the patterning and deposition of conductive materials to form interconnects on surfaces.

In the case where the capping layer is deposited from an electroless batch solution, such defects may additionally include contaminants deposited on the surface from the reaction solution.

Such defects can have additional causes when the surface is treated by polishing, such as chemical and mechanical polishing, after deposition of the interconnect, as is the usual case where copper is used in the interconnect. First, inherent defects may be formed on the surface from a small area of metal or metal oxide residue that has not been removed from the surface. Deposition of the capping material may be enhanced in this area. Such defects may also include particles remaining from the polishing slurry remaining on the surface.

One attempt to reduce the effect of the defect is described in US Pat. No. 5,478,436. The above describes a cleaning process after electroless deposition in which particles and contaminants remaining on the dielectric surface after the electroless deposition process are removed by a brushing process.

Conventional attempts to clean the dielectric and interconnect surfaces prior to deposition of the capping layer include cleaning using both inorganic acids and bases. However, the efficiency of this process is limited. Two other attempts are described in US Pat. No. 6,860,944 and US Pat. No. 2001/0018266.

US Pat. No. 5,358,743 describes the treatment of dielectric surfaces using ClSi (CH ₃ ) ₃ . The treatment is carried out prior to the deposition of the copper interconnect structure to increase the selectivity of copper deposition through chemical vapor deposition.

1 is a photograph of the surface of Comparative Example 1 after electroless deposition of a capping layer.

2 is a photograph of the surface of Example 1 after electroless deposition of a capping layer.

Accordingly, in a first aspect, the present invention relates to a method of forming a capping layer on a conductive interconnect for a semiconductor device, the method comprising:

(a) providing one or more conductors in the dielectric layer, and

(b) depositing a capping layer on the top surface of at least a portion of the one or more conductors,

The method additionally

(c) reacting the dielectric layer with an organic compound of formula I in a liquid phase before depositing the capping layer:

Wherein X is a functional group, R is an organic group or an organosiloxane group, Y ₁ is a functional group or an organic group or an organosiloxane group, and Y ₂ is a functional group or an organic group or an organosiloxane group, and the functional group NH ₂ , secondary amine, tertiary amine, acetamide, trifluoroacetamide, imidazole, urea, OH, alkyloxy, acryloxy, acetate, SH, alkylthiol, sulfonate, metanosulfonate, and cya Ide, and salts thereof.

As used herein, an organic group means a group which bonds to silicon in formula (I) via a carbon atom.

Organic compounds can be prepared in pure liquid form or in solution form. Although compounds of formula (I) may be provided for reaction with dielectric surfaces, it will be understood that hydrolysis at silicon atoms containing functional groups can often occur by reaction with water in solution. In this case, it will be understood that this is not the compound shown by formula I in which a substantial reaction with the surface is carried out. Instead, it may be a compound containing a Si—OH bond, or an oligomer of formula (I) in which molecules react to form a Si—O—Si bond. Therefore, the present invention also provides a reaction of the dielectric surface with the hydrolysis product of formula (I) after in situ reaction of the compound of formula (I) with water.

Functionalization of the dielectric surface by reaction of the dielectric surface with an organic compound may reduce the number and / or effect of defects on the dielectric surface. Thus, the functionalization can reduce the reactivity of the dielectric surface and the defects contained on the surface. The functionalization can three-dimensionally mask the surface and defects. These two effects can contribute to further reducing the deposition rate of the capping layer on the dielectric surface, thereby increasing the selectivity of the deposition process. The functionalization can also act to modify the surface properties of the dielectric surface. This not only results in steric shielding and responsiveness changes, but may also result in, for example, changes in the wettability of the surface. Thus, the functionalization can reduce the deposition rate of contaminants on the dielectric surface. Functionalization of the dielectric surface may also act as an initial cleaning process prior to the deposition of the capping layer to remove impurities on the dielectric surface in advance. For example, impurities remaining on the surface after deposition of the interconnect material may be removed. The impurities may include residues such as silica residues or carbon residues that remain on the surface, for example when the surface is polished prior to deposition of the capping layer.

Functionalization of the dielectric surface will typically involve depositing an organic compound on the dielectric surface while forming a chemical bond between the compound and the surface. In addition, physical interactions may occur, such as by hydrogen bonding, or electrostatic or even van der Waals interactions may be formed independent of or through any chemical bonds. It is also possible.

The functional groups in formula (I) can also be described as leaving groups. Without wishing to be bound by theory, the reaction of the surface with the organosilicon compound will generally proceed to nucleophilic substitution of the leaving group by water, a nucleophilic catalyst or by the hydroxyl group of the surface itself. Therefore, in this case, the leaving group is preferably defined as a group which can be substituted by nucleophiles under the reaction conditions.

In the present invention, the functional groups for X in Formula I, and optionally Y ₁ and optionally Y ₂ , are NH ₂ , secondary amines, tertiary amines, acetamides, trifluoroacetamides, imidazoles, ureas, Independently selected from OH, alkyloxy, acryloxy, acetate, SH, alkylthiol, sulfonate, metanosulfonate, and cyanide, and their salts.

In formula (I) it has been found that the selection of a functional group, for example NH ₂ , results in a sufficient rate in reaction with the dielectric surface in practical applications. Alternatively, some other functional groups such as halogens (eg chlorine) may exhibit relatively slow rates in reaction with the surface. Slow reaction rates are undesirable in practical applications because they increase treatment time and reduce the efficiency of the entire production process. Moreover, halogen functional groups such as chlorine may lead to the formation of undesirable byproducts and may require additional processing steps.

When certain preferred methods of applying the solution to the surface are considered, consideration of the reaction rate is particularly important. For example, particularly fast reaction times are required for applications in which the organosilicon compound is sprayed onto the dielectric surface in pure form or in solution. This is the case where the reaction solvent is expected to be able to evaporate rapidly on the dielectric surface.

Gas phase functionalization of the surface by organosilicon compounds requires complex equipment and very carefully controlled reaction conditions. However, the inventors have found that in a pretreatment step prior to deposition on the conductive interconnect of the capping layer, liquid phase treatment may be a much more practical technique for substrate processing. This is because it can be carried out with the same apparatus as the deposition of the capping layer, thereby eliminating the need for a special apparatus for surface functionalization.

Advantageously, functional group X, and optionally Y ₁ and / or optionally Y _2, is independently selected from primary amines, secondary amines, and tertiary amines, and salts thereof.

In a preferred embodiment, Y ₁ is a functional group and the functional group comprises an amino group or a protonated derivative thereof. In a preferred embodiment, the organic compound comprises a reactive organofunctional siloxane oligomer, which may be provided in water.

In another preferred embodiment, Y ₁ and Y ₂ are independently selected organic and / or organosiloxane groups, so all three independently selected organic and / or organosiloxane groups are attached to silicon. This may be advantageous because the shielding of the surface can be improved.

Preferably, the silicon in the organosilicon compound contains two independently selected functional groups and two independently selected organic and / or organosiloxane groups. In another embodiment, the silicon comprises one functional group and three independently selected organic groups and / or organosiloxane groups. The above embodiments are believed to be advantageous because they have two or more organic and / or organosiloxane groups attached to the silicon to better mask defects on the surface. In other words, the steric bulkability of the organic and / or organosiloxane groups may be advantageous, so that the incorporation of many organic and / or organosiloxane groups onto silicon may improve the steric shielding of the surface. This may protect and reduce the reactivity of any nucleophilic sites on the surface. Moreover, the introduction of two or more organic and / or organosiloxane groups on silicon allows the surface to be more protected from water than when only one organic group is used. Hydration and bulkability of the surface are kept to a minimum, so that the dielectric constant of the dielectric layer is also kept to a minimum, as described below.

In addition, the at least one organic group preferably contains a branching point as in the tertiary butyl group. These groups are believed to provide 'umbrella' on the dielectric surface to provide enhanced protection against defects on the surface. Additional protection of the dielectric surface may be provided by groups containing two or more branch points, such as 2,2,3-trimethylbutyl groups.

Preferably, the organosiloxane is an organosiloxane oligomer or organosiloxane polymer. More preferably, it has the structure of formula II:

Wherein Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ are independently selected from functional groups and / or organic groups as defined in claim 1 and n is a positive integer.

Preferably, n ranges from 1 to 20. More preferably, n is in the range of 1-5.

Examples of organosilicon compounds include hexamethyl-disilazane, trimethyldimethylaminosilane, dimethyl-t-butyldimethylaminosilane, and difunctional dimethylbis (dimethylamino) silane. . Examples of water soluble organosilanes include Dynasylan HS2627 and HS2909 supplied from Degussa. There is an organic amino-silane further comprising an organic group. A further example is Silicad supplied from Gelest having a chemical structure of C ₁₈ H ₃₇ Si (OH) ₃ .

Nucleophilic catalysts may also be added to the reaction solvent. Examples of additives include methanol, ethanol, ammonia and pyridine. In addition, these materials may be added to enhance the solubility of the organosilicon compound.

Advantageously, R and optionally one or both of Y ₁ and Y ₂ are independently selected from the following organic groups or organosiloxanes: organosiloxane oligomers, organosiloxane polymers, C ₁ To C ₂₅ alkyl, C ₂ to C ₂₅ alkenyl, C ₂ to C ₂₅ alkynyl, aryl, and C ₁ -C ₂₅ alkyl, C ₂ -C ₂₅ alkenyl and / or C ₂ -C ₂₅ alkynyl Aryl substituted by the above. Any of these groups may be partially or fully halogenated. Preferably, R and optionally one or both of Y ₁ and Y ₂ are methyl, ethyl, propyl, butyl, phenyl, pentafluorophenyl, 1,1,2-trimethylpropyl (thexyl) and Independently selected from allyl. In addition, any of these groups may be partially or fully halogenated.

The dielectric surface preferably contains hydroxyl groups or groups that hydrolyze under ambient aqueous environment to form hydroxyl groups. In this case, the functionalization of the dielectric surface preferably comprises the interaction of the surface groups, preferably the reaction.

Thus, the present invention may provide additional advantages. This is often the case when the surface dielectric constant is greater than the bulk dielectric constant. One reason for this is the presence of hydroxyl groups on the surface of the dielectric. Such hydroxyl groups can result in the absorption of favorable water on the surface. The absorbed water is believed to increase the dielectric constant at the surface. In addition, when the dielectric comprises a porous material, water molecules can be absorbed into the bulk material through the penetration of pores, thus increasing the bulk dielectric constant. Therefore, by functionalizing the surface through the interaction or reaction of hydroxyl groups, the uptake of water on the surface is less facilitated, thereby reducing the surface dielectric constant. If the dielectric layer is porous, functionalization can also keep the increase in bulk dielectric constant to a minimum due to water absorption.

In the case of silicon oxide-containing materials, surface hydroxyl groups are produced by the disruption or hydrolysis of Si—O—Si (siloxane) bonds at the surface of the material in reaction with moisture. Since these bonds are typically part of a 4 or 6 membered siloxane ring, these bonds are typically twisted. In addition, in other materials such as metal oxides, hydroxyl groups may also be formed at the surface by reaction with moisture.

In the case of porous dielectrics, the hydration of the surface and the hydration of the bulk material are particularly problematic. An advantage of the present invention is that it can solve certain problems related to hydration. First, when the surface is polished prior to the formation of the capping layer, this is usually done in the presence of an aqueous slurry. Therefore, treating the surface with an organic compound that interacts with or reacts with surface hydroxyl groups can simultaneously dehydrate the surface (by reaction with absorbed water), which can also lead to dehydration of the bulk material. In this way, the dielectric constant of the dielectric material can be advantageously reduced.

Secondly, when the capping layer is deposited from the aqueous solution onto the conductive interconnect, the presence of an organic layer on the dielectric surface can reduce or prevent the rate of water absorption on the dielectric surface during the deposition process. This, in turn, allows the dielectric constant of the dielectric surface and dielectric bulk to be kept to a minimum.

This may result in the added benefit of broadening the range of methods that can be used to process semiconductor devices, in particular semiconductor devices containing porous dielectrics. Therefore, chemical mechanical polishing and electroless deposition can now be used without requiring any steps to minimize hydration of the surface during this process.

Preferably, the process for forming the capping layer further comprises grinding the upper surface of the conductor so that the surface is substantially coplanar with the upper surface of the dielectric prior to functionalizing the upper surface of the dielectric layer. The polishing of the top surface of the one or more conductors preferably comprises conventional techniques of chemical mechanical polishing (CMP). In this case, pretreatment of the dielectric surface prior to deposition of the capping layer has the additional advantage of causing removal of residues remaining on the surface after polishing.

At least one conductor preferably comprises Cu or an alloy thereof. Alternatively, or in combination with the above, Ag or an alloy thereof may be used.

The dielectric layer preferably comprises an oxide of silicon or a carbonated oxide of silicon. Suitable examples include silicon dioxide or carbonated silicon dioxide. The dielectric layer may be a porous or nonporous layer.

The capping layer typically comprises a ternary alloy composition comprising a metal, typically an alloy of the metal, preferably one or more of Co, Ni, W, Mo, B, P and Sn. Suitable examples include CoP, CoB, CoWP, CoWB, CoMoB, CoWBP, NiP, NiB, NiMoP, and CoSnP.

The capping layer is preferably deposited by a process including electroless deposition. This process is optional so that the capping layer is essentially deposited only on the interconnect structure and not on the dielectric surface. This process involves placing the surface containing the interconnect in a salt solution of various metals to be incorporated into the alloy capping layer. The reducing agent is generally incorporated into the solution. It is believed that the reducing agent can promote the reduction of the metal salt to the metal. Acids or bases that change the pH of the solution may also be added to the solution. In addition, salts may be added to buffer the solution. Surfactants and / or complexing agents may also be incorporated into the plating solutions.

Solutions for electroless deposition of CoWPs include, for example, tungstate salts (WO ₄ ^2- ) such as sodium, ammonium salts or tetramethylammonium salts; Cobalt salts such as chlorides or sulfates; Hypophosphites such as sodium salts, ammonium salts or tetramethylammonium salts, EDTA may be added as a complexing agent, and tetramethyl-ammonium hydroxide may be added to change the pH. Citrate ions can be added to buffer the solution. Each of these components is added in solution at a rate ranging from 5 to 100 g per liter of water solvent. In addition, the surfactant may be added at a low concentration, such as in the range of 0.1 to 5 g per liter of solution. Preferably, the reaction solution is maintained in a temperature range of 40 to 90 ° C, more preferably in a temperature range of 45 to 60 ° C. The pH of the solution may be 8.5 to 13, preferably 8.5 to 9.5. Further details of the electroless deposition technique for metal cap layers can be found in Electrochim . Acta 44 , 3639-3649 (1999).

When the reaction of the dielectric surface with the organosilane is carried out in solution, care may be required to prevent excessive polymerization of the reactants. Excessive polymerization is characterized by clouding of the reaction solution. For example, polymerization is promoted by high concentrations of reactants. Therefore, the concentration of the compound of formula (I) or its hydrolysis product is preferably in the range of 10 ⁻⁴ to 10 ⁻² molcm ⁻³ .

Other advantageous reaction conditions include a reaction temperature of 20 to 85 ° C., preferably 20 to 50 ° C. The time for which the dielectric layer is left in the reaction solution is preferably 240 minutes or less, more preferably 30 minutes or less, more preferably 20 seconds to 5 minutes, further preferably 2 minutes or less.

The compounds of formula (I) can also be applied to the surface by spraying. More particularly, the compound may be dissolved in an organic solvent and sprayed onto the surface, or the compound may be applied onto the surface in pure form. Preferably, the compound may be sprayed on the surface under an inert atmosphere. Inert atmospheres should in principle contain very little or no moisture (eg, preferably less than 1% humidity). Inert atmospheres may also contain one or more gases of argon, nitrogen and / or carbon dioxide.

Functionalization can also be accomplished by the Langmuir-Blodgett technique.

The organosilicon compound may be added as a solution by itself or as a solution containing additives. In either case, treatment of the surface with a solution containing an organic component may occur before or after the cleaning of the surface, or after the cleaning of the surface occurs and treatment of the surface occurs again before cleaning. Can be. Such cleaning may comprise one or two of the following steps a) and b):

a) treatment with inorganic acids or inorganic bases such as ammonium persulfate, ammonium phosphate, ammonium fluoride or ammonium hydroxide;

b) treatment with organic acids or organic bases such as citric acid, oxalic acid, malic acid, acetic acid, tartaric acid, tetramethylammonium hydroxide, tetraethylammonium hydroxide, aminoethanol.

This step can be carried out in sequence (ie after step a), step b)) or in reverse order (ie step b) after step b), or one of the above steps is the treatment of the invention with organic components. May be carried out before the step, another step may be carried out after the treatment step of the present invention, or one or both of steps a) and b) may be carried out before the process of the present invention, or step a) One or both of b and b) may be carried out after the treatment of the present invention.

In a preferred embodiment, steps a) and b) are carried out prior to treating the surface with a solution containing only organic components, more preferably organosilicon compounds, such as compounds having the structure of formula I, in order to functionalize the dielectric surface. .

The pretreatment solution may comprise one or more of water and an organic solvent. Preferably, co-solvents are included, especially if the pretreatment solution is water-based. Co-solvents can enhance the solubility of solution components, such as surfactants. In addition, the co-solvent can make the distribution of the reaction solution and the components in the solution more uniform than in the absence of such co-solvent. Preferably, the co-solvent is an alcohol, more preferably ethanol and / or isopropyl alcohol (IPA).

In addition to the component having the structure of formula (I), the pretreatment solution may comprise a number of other additives.

For example, the solution may comprise a complexing agent such as EDTA (ethylenediaminetetraacetic acid) or a derivative or salt thereof. Complexing agents can assist in the removal of any metal species absorbed on the surface. Organic acids may also act as complexing agents.

The pretreatment solution may also include a surfactant to aid in the wetting of the pretreatment solution on the surface, to aid in the solubility of the various components in the solution, and / or to aid in cleaning the surface. Various surfactants can be used. It may be advantageous to use block copolymers of poly (ethyleneoxide) and poly (propylene) oxide. These two groups are effectively absorbed on the hydrophobic and hydrophilic surfaces, and the length and ratio of each group present in the block copolymer can be easily adjusted according to the application.

The pretreatment solution may be acidic or basic. If none of the steps a) and b) described above have been carried out before or after treating the surface with the pretreatment solution, the pretreatment solution preferably has a pH of less than 3. Thus, the pretreatment solution may comprise an acid, preferably an organic acid, for example citric acid and / or malic acid. The pretreatment solution may also comprise an inorganic acid, for example an ammonium salt such as ammonium persulfate.

As is apparent from the above, the present invention provides a precleaning step for selective electroless deposition in semiconductor configurations.

In a second aspect, the present invention relates to a method for forming a capping layer on a conductive interconnect for a semiconductor device, the method comprising

Providing at least one conductor comprising Cu or an alloy thereof to a dielectric layer comprising Si or an oxide thereof or a carbonated oxide thereof, and

Depositing a capping layer on the top surface of the one or more conductors,

Before depositing the capping layer, the method further comprises reacting the top surface of the dielectric layer with a reactive organofunctional organosiloxane oligomer.

Reactive organofunctional siloxane oligomers may be provided in the presence of water.

The features described above in connection with the first aspect may also be applied to the second aspect alone or in combination.

In a third aspect, the present invention relates to the provision of a conductive interconnect for a semiconductor device, which may be formed by a method as described herein.

In a fourth aspect, the present invention has (i) having at least one conductor provided on the top surface functionalized to reduce the number and / or effect of any defects on the dielectric surface or to modify the surface properties of the dielectric surface. A dielectric layer, and (ii) a capping layer provided on an upper surface of at least a portion of one or more conductors.

In a fifth aspect, the invention relates to a semiconductor device comprising a conductive interconnect as described above.

In a sixth aspect, the present invention relates to the use of an organic compound for functionalizing a dielectric layer having at least one conductor on its surface, wherein the use is a capping layer on at least a portion of at least a portion of the conductor. Reacting the dielectric layer with the organic compound prior to depositing the organic compound, wherein the organic compound has the structure of Formula I:

Formula I

Wherein X is a functional group, R is an organic group or an organosiloxane group, Y ₁ is a functional group or an organic group or an organosiloxane group, and Y ₂ is a functional group or an organic group or an organosiloxane group, and the functional group NH ₂ , secondary amine, tertiary amine, acetamide, trifluoroacetamide, imidazole, urea, OH, alkyloxy, acryloxy, acetate, SH, alkylthiol, sulfonate, metanosulfonate, and cya Ide, and salts thereof.

 The features described above in connection with the first aspect may be equally applied to the second, third, fourth, fifth and sixth aspects alone or in combination.

The invention will now be further described with reference to the following non-limiting examples.

Comparative Example 1

Conventional arrangements of copper interconnects on silicon dioxide surfaces were provided after chemical mechanical polishing. A solution containing 20 g citric acid, 20 g malic acid and 20 g ammonium persulfate was prepared in 1 liter of water. The pH of the solution was determined to be 2.8 to 2.9. The surface of the silicon dioxide / copper interconnect was immersed in the solution at 22 ° C. for 2 minutes in a beaker. The surface was then transferred to a solution for electroless deposition of capping layers, as described in US Patent Application 2005/0048773 (US Pat. No. 6,924,232) under the name of Freescale. The solution was treated at 55 ° C. for 50 seconds, after which the solution was removed and dried.

A photograph of the surface is shown in FIG. 1. The portions where the capping layer has been deposited on the dielectric surface can be clearly seen as dots of darker material on the brighter dielectric surface. This non-selective deposition of the capping layer is believed to be the result of the residue on the dielectric surface.

Example 1

Conventional arrangements of copper interconnects on silicon dioxide surfaces were provided after chemical mechanical polishing. A solution containing 20 g citric acid, 20 g malic acid and 20 g ammonium persulfate was prepared in 1 liter of water. 0.5 wt% Sivento Dynasylan HS2627 was added thereto. The civento dynasilane HS2627 is supplied by Degussa, which is known to be a soluble siloxane oligomer in water. The siloxane oligomers additionally comprise amino and organic groups attached to silicon. The pH of the solution was determined to be 2.9. The surface of the silicon dioxide / copper interconnect was immersed in the solution at 22 ° C. for 2 minutes in a beaker. The surface was then transferred to a solution for electroless deposition of a capping layer, as described in US Patent Application 2005/0048773 in the name of Freescale. The solution was treated at 55 ° C. for 50 seconds, after which the solution was removed and dried.

A photograph of the surface is shown in FIG. 2. Unlike Comparative Example 1, a clean surface was observed, which means that the selective deposition of the capping layer was larger than in the case of Comparative Example.

Claims (38)

A method of forming a capping layer on a conductive interconnect for a semiconductor device, the method comprising: (a) providing one or more conductors in the dielectric layer, and (b) depositing a capping layer on the top surface of at least a portion of the one or more conductors, (c) reacting the dielectric layer with an organic compound of formula (I) in a liquid phase before depositing the capping layer: Formula I

Where X is a functional group, R is an organic group or an organosiloxane group, Y ₁ is a functional group or an organic group or an organosiloxane group, Y ₂ is a functional group or an organic group or an organosiloxane group, and the functional group is NH ₂ , Secondary amines, tertiary amines, acetamide, trifluoroacetamide, imidazole, urea, OH, alkyloxy, acryloxy, acetate, SH, alkylthiol, sulfonate, metanosulfonate, and cyanide, and Independently from these salts. The method of claim 1, Prior to reacting the dielectric layer with the organic compound, the method further comprises polishing the top surface of the at least one conductor so that the surface is substantially flush with the top surface of the dielectric. The method of claim 2, Wherein the polishing of the top surface of the one or more conductors comprises chemical mechanical polishing (CMP). The method according to any one of claims 1 to 3, At least one conductor comprises Cu or an alloy thereof, or Ag or an alloy thereof. The method according to any one of claims 1 to 4, Wherein the dielectric layer comprises an oxide of silicon or a carbonated oxide of silicon. The method of claim 5, wherein Wherein the dielectric layer comprises silicon dioxide or carbonated silicon dioxide. The method according to any one of claims 1 to 6, The dielectric layer is a porous layer. The method according to any one of claims 1 to 7, And the capping layer comprises an alloy. The method of claim 8, And the capping layer comprises a ternary alloy composition. The method of claim 9, The ternary alloy composition comprises one or more of Co, Ni, W, Mo, B, P, and Sn. The method according to any one of claims 1 to 10, The capping layer comprises CoP, CoB, CoWP, CoWB, CoMoB, CoWBP, NiP, NiB, NiMoP, and CoSnP. The method according to any one of claims 1 to 11, The capping layer is deposited by electroless deposition. The method according to any one of claims 1 to 12, R, and optionally one or both of Y ₁ and Y ₂ is an organosiloxane oligomer, an organosiloxane polymer, C ₁ To C ₂₅ alkyl, C ₂ to C ₂₅ alkenyl, C ₂ to C ₂₅ alkynyl, aryl, and C ₁ -C ₂₅ alkyl, C ₂ -C ₂₅ alkenyl and / or C ₂ -C ₂₅ alkynyl Independently selected from organic groups and organosiloxane groups selected from the above substituted aryl. The method of claim 13, Wherein the organosiloxane oligomer or organosiloxane polymer has the structure of Formula II: Formula II

Wherein Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ are independently selected functional groups and / or organic groups as defined in claim 1 and n is a positive integer. The method of claim 14, n is in the range 1-20. The method of claim 15, n is in the range 1-5. The method according to any one of claims 1 to 16, Wherein the organic group contains at least one branch point. The method of claim 17, Wherein the organic group contains at least two branch points. The method according to any one of claims 1 to 18, A compound of formula I is hydrolyzed before reacting with the dielectric surface. The method according to any one of claims 1 to 19, Reacting the dielectric surface with an organic compound is carried out in a solvent comprising an organic solvent. The method according to any one of claims 1 to 20, Reacting the dielectric surface with an organic compound is carried out in a solvent comprising water. The method according to any one of claims 1 to 21, Reacting the dielectric surface with an organic compound is carried out in a solution comprising an acid and / or a surfactant. A method of forming a capping layer on a conductive interconnect for a semiconductor device, the method comprising: Providing at least one conductor comprising Cu or an alloy thereof to a dielectric layer comprising Si or an oxide thereof or a carbonated oxide thereof, and Depositing a capping layer on the top surface of the one or more conductors, Prior to depositing the capping layer, further comprising reacting the top surface of the dielectric layer with a reactive organofunctional organosiloxane oligomer. The method of claim 23, A reactive organofunctional siloxane oligomer is provided in the presence of water. 25. A conductive interconnect for a semiconductor device formed by the method as defined in any one of claims 1 to 24. (i) a dielectric layer having at least one conductor provided on a top surface functionalized by reacting an organic compound of formula (I) with a dielectric surface in a liquid phase, and (ii) a capping layer provided on the top surface of at least a portion of the at least one conductor. Conductive Interconnect for Semiconductor Devices Formula I

Wherein X is a functional group, R is an organic group or an organosiloxane group, Y ₁ is a functional group or an organic group or an organosiloxane group, and Y ₂ is a functional group or an organic group or an organosiloxane group, and the functional group NH ₂ , secondary amine, tertiary amine, acetamide, trifluoroacetamide, imidazole, urea, OH, alkyloxy, acryloxy, acetate, SH, alkylthiol, sulfonate, metanosulfonate, and cya Ide, and salts thereof. The method of claim 26, A conductive interconnect in which the organic compound is a reactive organofunctional siloxane oligomer. The method of claim 26 or 27, At least one conductor comprises Cu or an alloy thereof, or Ag or an alloy thereof. The method according to any one of claims 26 to 28, A conductive interconnect in which the dielectric layer comprises an oxide of silicon or a carbonated oxide of silicon. The method of claim 29, A conductive interconnect in which the dielectric layer comprises silicon dioxide or carbonated silicon dioxide. The method according to any one of claims 26 to 30, Conductive interconnect wherein the dielectric layer is a porous layer. The method according to any one of claims 26 to 31, A conductive interconnect in which the capping layer comprises an alloy. The method of claim 32, A conductive interconnect wherein the capping layer comprises a ternary alloy composition. The method of claim 33, wherein A conductive interconnect wherein the ternary alloy composition comprises at least one of Co, Ni, W, Mo, B, P, and Sn. The method according to any one of claims 26 to 34, wherein Wherein the capping layer comprises CoP, CoB, CoWP, CoWB, CoMoB, CoWBP, NiP, NiB, NiMoP, and CoSnP. The method according to any one of claims 26 to 35, A conductive interconnect in which the capping layer is an electroless deposited capping layer. 37. A semiconductor device comprising a conductive interconnect as defined in any of claims 25-36. As a use of an organic compound for functionalizing a dielectric layer having at least one conductor on its surface, A method comprising reacting an organic compound of formula (I) with a dielectric layer prior to depositing a capping layer on at least a portion of at least a portion of the conductor: Formula I

Wherein X is a functional group, R is an organic group or an organosiloxane group, Y ₁ is a functional group or an organic group or an organosiloxane group, and Y ₂ is a functional group or an organic group or an organosiloxane group, and the functional group NH ₂ , secondary amine, tertiary amine, acetamide, trifluoroacetamide, imidazole, urea, OH, alkyloxy, acryloxy, acetate, SH, alkylthiol, sulfonate, metanosulfonate, and cya Ide, and salts thereof.

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