EP4634963A1

EP4634963A1 - Solution for post etch residue removal (perr)

Info

Publication number: EP4634963A1
Application number: EP23821681.6A
Authority: EP
Inventors: Haci Osman GUEVENC; Andreas Klipp
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2022-12-16
Filing date: 2023-12-13
Publication date: 2025-10-22
Also published as: WO2024126548A1; JP2026500331A; CN120345054A; TW202436608A; KR20250124121A

Abstract

The present invention relates to a composition for removing post etch residues from a substrate, the substrate comprising a surface of a molybdenum layer, the composition comprising: (a) 10 to 60 % by weight of a water-miscible organic solvent; (b) 4 to 15 % by weight of a C₁-C₁₂ amine; (c) 0.5 to 4 % by weight of a C₄ to C₁₆ quaternary ammonium hydroxide; (d) 0.1 to 5 % by weight of a C₂ to C₁₀ polyol; (e) 0.01 to 3 % by weight of a polyethyleneimine; and (f) water.

Description

Solution for post etch residue removal (PERR)

The present invention relates to a composition, its use and a process for post etch residue removal (PERR) of substrates, particularly semiconductor substrates, comprising molybdenum.

Background of the Invention

Resists such as deep UV photo resists or electron beam resists are used in the microlithographic technique for producing a wide range of electrical devices, e.g. semiconductor integrated circuits (ICs), liquid crystal panels, organic electroluminescent panels, printed circuit boards, micro machines, DNA chips and micro plants, in particular ICs with LSI (large-scale integration) or VLSI (very-large-scale integration).

Copper is customarily used as the low electrical resistance or wiring material in the electrical devices, in particular in the vias and interconnects contained in the ICs. The increasing use of copper and the ever decreasing dimensions of the electrical structures together with the ever increasing functionalities of the ICs require the use of low-k and ultra low-k materials in order to avoid problems with wiring resistance and wiring delay caused by high wiring capacities. These challenging developments have demanded and still demand the continuing optimization of the methods of manufacture and of the materials utilized therefore.

Although damascene patterning had to overcome many technical challenges, copper-based interconnects have been around for many consecutive technology nodes. As we are progressing toward local BEOL interconnect metal pitches of 20 nm and smaller (for technology nodes beyond N2), the resistance of Cu metal lines increases very fast at such small dimensions due to electron scattering at surfaces and at grain boundaries. Moreover, Cu metal lines require a liner to prevent Cu diffusion in the dielectric material. As this liner needs a fixed thickness to prevent diffusion, scaling Cu interconnects without being able to scale the liner thickness results in a significant relative increase in metal resistance as a function of reducing critical dimension.

Two interesting candidates, which are expected to have a lower resistance than Cu at very small dimensions, are ruthenium (Ru) and molybdenum (Mo). An important advantage for Ru and Mo is that both materials can be patterned by direct metal etch, as was the case with Al before the Cu-interconnect era. Moreover, as both Ru and Mo can be integrated barrierless, a reduction in resistance can be expected when integrating Ru or Mo at small dimensions.

Molybdenum may have many of the advantages sought in the art. For example, it may be useful as a conductor in back end of line (BEOL) or mid end of line (MEOL) applications, or in buried power rail or in work function layer in logic applications and in word or bit line in advanced memory applications. For copper, many so-called all-wet post-etch residue removal (PERR) processes have been developed and disclosed in the prior art.

WO 2010/127941 A discloses a post etch residue removal composition comprising a liquid composition being free from N-alkylpyrrolidones and hydroxyl amine and hydroxyl amine derivatives and comprising at least two polar organic solvents, selected from the group consisting of solvents exhibiting in the presence of from 0.06 to 4% by weight of dissolved tetramethylammonium hydroxide, the weight percentage being based on the complete weight of the respective test solution, a constant removal rate at 50°C for a 30 nm thick polymeric barrier anti-reflective layer containing deep UV absorbing chromophoric groups, and at least one quaternary ammonium hydroxide.

Patterning challenges for direct metal etch of ruthenium and molybdenum at 32 nm metal pitch and below are e.g. described in J. Vac. Sci. Technol. B 40, 032802 (2022). They expect to have approx 2 nm of MoO_x sidewalls on the Mo metal lines, patterned with their direct metal etch process and even more in larger lines which could be a major showstopper for integrating Mo in the future interconnects.

Therefore, there is a strong need for cleaning compositions that are capable of cleaning wafer structures comprising molybdenum which show, besides the removal of all other etch residues, particularly dry etch residues

(a) a low molybdenum static etch rate that avoids damaging the structures since molybdenum is less noble than copper;

(b) a good, preferably complete, removal of molybdenum etch residues, particularly etch residues that include molybdenum oxides.

It is therefore an object of the invention to provide a composition for post etch residue removal that allows good PERR efficiency, removal of the etch residues, particularly the molybdenum etch residues, most particularly the molybdenum oxide residues, and good compatibility with the substrate, particularly with molybdenum. It is a further object of the invention to provide a composition that shows essentially complete removal of molybdenum etch residues (essentially oxides) while essentially not attacking the molybdenum.

Summary of the Invention

One embodiment of the present invention is a composition for removing post etch residues from a substrate, the substrate comprising a surface of a molybdenum layer, the composition comprising:

(a) 10 to 60 % by weight of a water-miscible organic solvent

(b) 4 to 15 % by weight of a C1-C12 amine;

(c) 0.5 to 4 % by weight of a C4 to C16 quaternary ammonium hydroxide; (d) 0.1 to 5 % by weight of a C2 to C10 polyol;

(e) 0.01 to 3 % by weight of a polyethyleneimine; and

(f) water.

The composition is also capable of removing essentially all etch residues while effectively protecting the molybdenum conductor lines.

Another embodiment of the present invention is the use of a composition as described herein for removing post etch residues from a semiconductor substrate comprising a surface of a molybdenum layer.

Yet another embodiment of the present invention is a process of removing post etch residues from a substrate, the substrate comprising a surface of a molybdenum layer, the composition comprising:

(a) providing a microelectronic device surface that includes the surface of the molybdenum layer and post etch residues thereon;

(b) providing a composition as described herein;

(c) contacting the surface with the composition for a time and at a temperature effective to remove the post etch residues while not compromizing the molybdenum layer.

Brief description of the Figures

Fig. 1 shows a scheme of the substrate used in example 3;

Fig. 2 shows a substrate that was treated with composition C1.1 of example 3;

Fig. 3 shows a substrate that was treated with composition 1.4 of example 3.

Detailed Description of the Invention

The composition of the subject invention comprises:

(a) 10 to 60 % by weight of a water-miscible organic solvent

(b) 4 to 15 % by weight of a C1-C12 amine;

(c) 0.5 to 4 % by weight of a C4 to C16 quaternary ammonium hydroxide;

(d) 0.1 to 5 % by weight of a C2 to C10 polyol;

(e) 0.01 to 3 % by weight of a polyethyleneimine; and

(f) water.

Definitions

As used herein, “layer” means a part of a substrate that was separately disposed on the surface of a substrate and has a distinguishable composition with respect to adjacent layers. The term “C_x” means that the respective group comprises x numbers of C atoms. The term "C_x to C_y alkyl" means alkyl with a number x to y of carbon atoms and, unless explicitly specified, includes unsubstituted linear, branched and cyclic alkyl. As used herein, “alkanediyl” refers to a diradical of linear, branched or cyclic alkanes or a combination thereof.

All percent, ppm or comparable values refer to the weight with respect to the total weight of the respective composition except where otherwise indicated. The terms “wt%” and “% by weight” are used herein synonymously.

A “post-etch residue” refers to a material remaining following a gas-phase plasma etching process, e.g., back-end-of-line (“BEOL”) dual damascene processing, or wet etching processes. A post-etch residue may be organic, organometallic, organosilicic, or inorganic in nature, for example, silicon-containing material, carbon-based organic material, and etch gas residues such as oxygen and fluorine. When molybdenum layers are etched, molybdenum etch residues such as molybdenum oxides may be present and are usually present. Depending on the substrates and the method of etching such molybdenum oxides may also contain other non- oxidic compounds.

All cited documents are incorporated herein by reference.

Water-miscible organic solvent

The cleaning composition comprises one or more water-miscible organic solvents. These help dissolving other components in the composition and improving the efficiency and solubility of organic residue removal from the wafer surface.

The term “water-miscible organic solvent” in the context of the present invention preferably means that an organic solvent fulfilling this requirement is miscible with water at least in a 1 :1 (w/w) ratio at 20 °C and ambient pressure.

Examples of water-miscible organic solvents that can be employed are

(a) ethers, such as but not limited to tripropylene glycol methyl ether, propylene glycol propyl ether, diethylene gycol n-butyl ether (BDG), dipropylene glycol methyl ether (DPM);

(b) sulfur-containing solvents:

(i) sulfones, such as but not limited to sulfolane;

(ii) sulfoxides, such as but not limited to dimethylsulfoxide (DMSO);

(c) alcohols, such as but not limited to tetrahydrofurfuryl alcohol or linear or branched C2 to Ce alkanols like ethanol, n-propanol or isopropanol;

(d) 4-methylmorpholine-4-oxide, trimethylamine-N-oxide, triethylamine-N-oxide, triethanolamine-N-oxide, pyridine-N-oxide, N-formyl-morpholine, N-ethylmorpholine-N- oxide, N-ethylpyrrolidine-N-oxide; or (e) mixtures thereof.

The water-miscible organic solvent may be protic or aprotic. Preferably the water-miscible organic solvent is aprotic.

Preferred solvents are dimethylsulfoxide, diethylsulfoxide, methylethyl-sulfoxide, dipropyl sulfoxide, diphenylsulfoxide, methylphenylsulfoxide and 1 ,1’-dihydroxyphenyl sulfoxide, and sulfolane, or mixtures thereof. Most preferred solvents are dimethylsulfoxide, sulfolane, and a mixture thereof.

For most applications, the amount of water-miscible organic solvent in the composition may be in a range having start and end points selected from the following list of weight percents: 10, 12, 15, 20, 25, 29, 30, 33, 35, 40, 45, 50, 54, 59.9, and 60. Examples of such ranges of solvent include from about 10 to about 60 % by weight; or from about 12 to about 50 % by weight; or from about 15 to about 45 % by weight; or from about 0.5 % to about 30% by weight; or from about 1 to about 30 % by weight; or from about 12 to about 40 % by weight; or from about 20 to about 49.9 %, or from about 25 to about 55 % by weight; or from about 30 to about 40 % by weight of the composition.

In individual cases, a composition according to the invention as defined herein may further comprise as an optional additional component: One or more water-miscible organic solvents, preferably selected from the group consisting of tetra hydrofuran (THF), N-methylpyrrolidone (NMP), dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), ethanol, isopropanol, butyldiglycol, butylglycol, sulfolane (2,3,4,5-tetrahydrothiophene-1 ,1-dioxide) and mixtures thereof; more preferably selected from the group consisting of THF, NMP, DMF, DMSO, sulfolane and mixtures thereof.

In a preferred embodiment, the total amount of the one or more water-miscible organic solvents the cleaning composition is of from about 15 to about 55 % by weight, preferably of from about 20 to about 50 % by weight, more preferably of from about 25 to about 45 % by weight, even more preferably of from about 30 to about 40 % by weight, based on the total weight of the composition.

Amine

The cleaning composition comprises one or more amines. These help to remove the polymer residues from the wafer substrate.

Preferably the amine is different from any other components in the composition, particularly the water-miscible organic solvent and the polyol. More preferably the amine does not comprise any other substituents than amino and hydroxyl, particularly does not comprise any other substituents than amino and one single hydroxyl. In a preferred embodiment the amine is selected from a Ci to Cw alkylamine and a C2 to C10 alkanolamine. Most preferred are C2 to C10 alkanolamines.

Alkylamines are chemical compounds that include an amine group that is substituted by at least one alkyl. The alkylamine can be any alkylamine that will be effective as a cleaning compound as described, including primary, secondary, and tertiary amine compounds. Certain useful alkylamines are monoalkylamines such as ethylamine, ethylenediamine, diethylenetriamine, triethylenediamine, tetraethylenepentamine (TEPA), triethylenetetraamine, ethylenediamine, hexamethylenediamine, triethylamine, trimethylamine, diglycolamine, and morpholine.

Preferred alkylamines are those comprising one or two primary, secondary or tertiary amino groups. Even more preferred are alkylamines

(a) comprising one primary amino group;

(b) comprising one secondary or tertiary amino group.

Alkanol amines are chemical compounds that include an amine group that is substituted by at least one hydroxy group, preferably one single hydroxy group. The alkanol amine can be any alkanol amine that will be effective as a cleaning compound as described, including primary, secondary, and tertiary amine compounds. The alkanol amine compound will have at least one alkanol substituent (e.g., methanol, ethanol, etc.), and one, two, or three alkanol, alkyl, or alternate organic substituents. Certain useful alkanol amines are primary alkanol amines such as monoethanol amine (MEA), aminoethylethanolamine, N-methylaminoethanol, aminoethoxyethanol, aminoethoxyethoxyethanol, butoxypropylamine, methoxypropylamine, butoxyisopropylamine, 2-ethylhexylisopropoxyamine, ethanolpropylamine, ethylethanolamine, n-hydroxyethylmorpholine, aminopropyldiethanolamine, dimethylaminoethoxyethanol, diethanolamine, N-methyldiethanolamine, monoethanolamine, triethanolamine, 1-amino-2- propanol, 3-amino-1-propanol, diisopropylamine, aminomethylpropanediol, N,N- dimethylaminomethylpropanediol, aminoethylpropanediol, N,N-dimethylaminoethylpropanediol, isopropylamine, 2-amino-1-butanol, aminomethylpropanol, aminodimethylpropanol, N,N- dimethylaminomethylpropanol, isobutanolamine, diisopropanolamine, 3-amino,4-hydroxyoctane, 2-aminobutylanol, tris(hydroxymethyl)aminomethane (TRIS), N,N-dimethyltris(hydroxymethyl)- aminomethane, hydroxyproplyamine, hydroxyethyl amine, tris(hydroxyethyl)aminomethane, and combinations thereof.

Preferred alkonolamines are those comprising one or two hydroxy groups and one or two primary, secondary or tertiary amino groups. Even more preferred are alkonolamines

(a) comprising one or two hydroxy groups and one secondary or tertiary amino group;

(b) comprising one hydroxy group and one or two secondary or tertiary amino groups.

A particularly preferred alkanolamine is 2-(Methylamino)ethan-1-ol (N-methylaminoethanol). The one or more amines may be present in an amout of from about 4 to about 15 % by weight, preferably from about 5 to about 14 % by weight, more preferably from about 6 to about 11.5 % by weight, even more preferably from about 7 to about 13 % by weight, most preferably from about 8 to about 12 % by weight.

Quaternary ammonium hydroxide

The cleaning composition comprises one or more C4 to C16 quaternary ammonium hydroxide as pH adjuster to adjust the pH to an alkaline range.

The quaternary ammonium hydroxide may be present in the composition in an amount of from about 0.5 to about 4 % by weight. Preferably the composition of the invention comprises, of from 0.7 to 3,5 % by weight, more preferably of from 1 to 3 % by weight, and most preferably of from 1.5 to 2.5% by weight of at least one quaternary ammonium hydroxide.

Preferably, the quaternary ammonium hydroxide may be selected from the group consisting of tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, and (2-hydroxyethyl)triethylammonium hydroxide.

Preferably the quaternary ammonium hydroxide may be selected from a C4 to Cs alkyl quaternary ammonium hydroxide, particularly from tetramethylammonium hydroxide and tetraethylammonium hydroxide.

Polyol

The cleaning composition comprises one or more C2 to C10 polyols. These help to increase the surface wetting and to dissolve polymer residues from the wafer surface.

Preferably the polyol is different from any other components in the composition, particularly the water-miscible organic solvent and the amine. More preferably the polyol does not comprise any other substituents than hydroxyl.

In a preferred embodiment the C2 to C10 polyol is selected from a compound of formula HOCH2(CHOH)kCH2OH, wherein k is 0 or an integer of from 1 to 8.

In a preferred embodiment the C2 to C10 polyol is selected from ethylene glycol, glycerol, erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol, galactitol, fucitol, iditol, inositol, volemitol, propylene glycol, 1 ,4-butanediol, diethylene glycol, and combinations thereof.

Particularly preferred is a combination of a C4 to Cs polyol, preferably sorbitol, and a C2 or C3 polyol, preferably ethylene glycol. The polyol may be present in an amount of from about 0.1 to about 5 % by weight of a C2 to C10 polyol, preferably from about 0.2 to about 4.5 % by weight, more preferably from about 0.3 to about 4 % by weight, even more preferably from about 0.4 to about 3 % by weight, most preferably from about 0.5 to about 2.5 % by weight.

In a preferred embodiment the polyol comprises or essetially consists of from about 0.3 to 1 % by weight of a C4 to Cs polyol and of from about 0.5 to 1.5 % by weight of a C2 or C3 polyol.

Polyethyleneimine (PEI)

The cleaning composition comprises one or more polyethyleneimine type molybdenum corrosion inhibitors. The polyethyleneimine significantly reduces corrosion of molybdenum, particularly molybdenum metal lines, when removing post etch residues from the wafer surface.

It was found that the addition of polyethyleneimines lead to a low etching rate on blanket PVD Mo compared to the composition without polyethyleneimines but still allows a good, preferably a complete removal of etch residues.

Polyethyleneimine backbones are to be understood as meaning compounds which consist of a saturated hydrocarbon chain with terminal amino functions which is interrupted by secondary and tertiary amino group. Such backbones may be linear or branched. Different polyethyleneimine backbones can of course be used in a mixture with one another.

Said backbones on comprise primary, secondary and tertiary amine nitrogen atoms connected by "linking" units. The backbone comprises essentially three types of units, and it needs to be emphasized that these groups may be distributed along the backbone in any order.

The units which make up the polyalkyleneimine backbones are (a) primary units having the formula:

[H2N-C2H4]- and -NH₂ which terminate the main backbone and any branching chains;

(b) secondary amine units having the formula: and (c) tertiary amine units having the formula: which are the branching points of the main and secondary backbone chains, A^E1 representing a continuation of the chain structure by branching. Continuation of the chain structure by branching here means that A^E1 may contain all primary, secondary and tertiary amine units described above except termination group -NH2.

During the formation of the polyamine backbones cyclization may occur, therefore, an amount of cyclic polyamine may be present in the parent polyalkyleneimine backbone mixture. Each primary and secondary amine unit of the cyclic alkyleneimines undergoes modification by the addition of polyoxyalkylene units in the same manner as linear and branched polyalkyleneimines.

The polyalkyleneimines of the present invention can be prepared, for example, by polymerizing ethyleneimine in the presence of a catalyst such as carbon dioxide, sodium bisulfite, sulfuric acid, hydrogen peroxide, hydrochloric acid, acetic acid, etc. Specific methods for preparing these polyalkyleneimine backbones are disclosed in U.S. Patent 2,182,306, U.S. Patent 3,033,746, U.S. Patent 2,208,095, U.S Patent 2,806,839, and U.S Patent 2,553,696.

In addition, the polyalkyleneimine backbones may be partly substituted by alkylating agents. The substituents may be selected from a Ci to C12 alkyl, C2 to C12 alkenyl, C2 to C12 alkynyl, Ce to C20 alkylaryl, Ce to C20 arylalkyl, Ce to C20 aryl. Preferred substituents may be selected from a Ci to Ce alkyl, Ce to C12 alkylaryl, Ce to C12 arylalkyl, and Ce to C12 aryl. It is preferred that the aryl group is phenyl or naphthyl. Also the terminating groups [H2N-X¹-¹]- and -NH2 may be substituted by groups R^L3.

Suitable examples for alkylating agents are organic compounds which contain active halogen atoms, such as arylalkyl halides, alkyl, alkenyl and alkynyl halides, and the like. Additionally, compounds such as alkyl sulfates, alkyl sultones, epoxides, and the like may also be used. Nonlimiting examples of corresponding alkylating agents comprise benzyl chloride, propane sultone, dimethyl sulphate, (3-chloro-2-hydroxypropyl) trimethyl ammonium chloride, or the like. Preference is given to using dimethyl sulphate and/or benzyl chloride. In a preferred embodiment the polyethyleneimine is unsubstituted. Depending of the pH of the composition, the amino groups in the polyethyleneimine may be present in its protonated form.

The mass average molecular mass M_w of the polyalkyleneimine may be of from about 800 g/mol to about 50 000 g/mol. The lower limit of the weight average molecular mass M_w of the polyalkyleneimine backbones is generally about 800 g/mol, preferably about 1 200 g/mol, more preferably about 1 500 g/mol. The upper limit of the weight average molecular mass M_w is generally about 50 000 g/mol, preferably about 25 000 g/mol, more preferably about 20 000 g/mol, most preferably about 10 000 g/mol. A particularly preferred range is of from 800 to 25.000 g7mol, most particularly 1000 to 4000 g/mol. The molecular mass may be determined by size exclusion chromatography like GPC using polymethylmethacrylate (PMMA) as standard and hexafluorisopropanol + 0.05% potassium trifluoracetate as eluent.

The polyethyleneimine may be present in an amount of from about 0.01 to about 3 % by weight, preferably from about 0.015 to about 2 % by weight, more preferably from about 0.2 to about 1 .5 % by weight, even more preferably from about 0.2 to about 1 % by weight, most preferably from about 0.2 to about 0.5 % by weight. It was found that even low amounts of polyethyleneimine are sufficient to protect the molybdenum on the wafer surface. A further increase of the concentration is possible but does not significantly improve the corrosion inhibiting performance of the polyethyleneimine.

Water

The etching compositions of the present invention are aqueous-based and, thus, comprise water. Water has several functions such as, for example, to dissolve one or more components of the composition, as a carrier of the components, as an aid in the removal of residue, as a viscosity modifier of the composition, and as a diluent. Preferably, the water employed in the composition is de-ionized (DI) water. The ranges of water described in the next paragraph include all of the water in the composition from any source.

For most applications, the weight percent of water in the composition will be present in a range with start and end points selected from the following group of numbers: 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 92, 94, 96. Examples of the ranges of water that may be used in the composition include, for examples, from about 20 to about 80 % by weight, or about 25 to about 75% by weight of water; or from about 30 to about 72 % by weight, or from about 35 to about 70 % by weight, or from about 40 to about 65 % by weight, or from about 45 to about 55 % by weight. Still other preferred embodiments of the present invention may include water in an amount to achieve the desired weight percent of the other ingredients. Dispersing agent

The composition may further comprise a dispersing agent in the form of polyalkoxylated polyethyleneimines. “Polyalkoxylated polyethyleneimine” means a polyethyleneimine which N- hydrogen atoms are substituted by a polyoxyalkylene group comprising C2 to Ce oxyalkylene units, preferably C2 to C4 oxyalkylene repeat units, more preferably C2 to C3 oxyalkylene repeat units, most preferably C2 oxyalkylene repeat units. The polyalkoxylated polyethyleneimines in combination with the polyethyleneimine further supports the cleaning of the wafer surface.

Generally, the polyalkyleneimine backbones of the polyalkoxylated polyalkyleneimines can be prepared as described above. The polyalkoxylation then is performed by reacting the respective alkylene oxides with the polyalkyleneimines, particularly the polyethyleneimines. The synthesis of polyalkylene oxide groups is known to those skilled in the art. Comprehensive details are given, for example, in “Polyoxyalkylenes” in Ullmann’s Encyclopedia of Industrial Chemistry, 6^th Edition, Electronic Release. When two or more different alkylene oxides are used, the polyoxyalkylene groups formed may be random copolymers, gradient copolymers or block copolymers.

The modification of the N-H units in the polymer backbone with oxyalkylene units is carried out, for instance, by first reacting the polymer, preferably polyethyleneimine, with one or more alkylene oxides, preferably ethylene oxide, propylene oxide, or mixtures thereof, in the presence of up to 80 % by weight of water at a temperature of from about 25 to about 150 °C in an autoclave fitted with a stirrer. In the first step of the reaction alkylene oxide is added in such an amount that nearly all hydrogen atoms of the N-H-units of the polyalkyleneimine are converted into hydroxyalkyl groups to give monoalkoxylated polyalkyleneimines. The water is then removed from the autoclave. After the addition of a basic catalyst, for example sodium methylate, potassium tertiary butylate, potassium hydroxide, sodium hydroxide, sodium hydride, potassium hydride or an alkaline ion exchanger in an amount of 0.1 to 15 % by weight with reference to the addition product obtained in the first step of the alkoxylation, further amounts of alkylene oxide are added to the reaction product of the first step so that a polyalkoxylated polyalkyleneimine is obtained which contains the intended average number of alkylene oxide units per N-H unit of the polymer. A second step may be carried out for instance at temperatures of from about 60 to about 150 °C. The second step of the alkoxylation may be carried out in an organic solvent such as xylene or toluene. For the correct metered addition of the alkylene oxides, it is advisable, before the alkoxylation, to determine the number of primary and secondary amine groups of the polyalkyleneimine. Alternately, the polyal koxylation may also be achieved by graft-copolymerization of polyethyleneimine.

The polyal koxylated polyalkyleneimines may optionally be functionalized with functional groups different from H in a further reaction step. An additional functionalization can serve to modify the properties of the polyalkoxylated polyalkyleneimines. To this end, the hydroxyl groups present in the polyoxyalkylated polyalkyleneimines are converted by means of suitable agents, which are capable of reaction with hydroxyl groups.

The type of functionalization depends on the desired end use. According to the functionalizing agent, the chain end can be hydrophobized or more strongly hydrophilized. Esterification of the hydroxy groups with acids is one representative reaction.

In one embodiment the alkoxylated polyalkyleneimines are used without any further functionalization.

In another embodiment the carboxylic functionalized polyalkoxylated polyethyleneimines may be obtained by Michael addition reaction with suitable a, p-unsaturated species, such as acrylic acid, methacrylic acid, among others. Preferably, the polyalkoxylated polyethyleneimine is functionalized with carboxylic acid groups. The Michael addition or Michael 1 ,4 addition is a reaction between a Michael donor (an enolate or other nucleophile such as amines) and a Michael acceptor (usually an a, p-unsaturated carbonyl/carboxyl) to produce a Michael adduct by creating a carbon-carbon bond at the acceptor's p-carbon. Such reactions are also called aza-michael additions. Further description of the same is provided in- Additions to and substitutions at C-C TT-Bonds, M. Mauduit, A. Denicourt-Nowicki, in Comprehensive Organic Synthesis (Second Edition), 2014.

Furthermore, the polyalkoxylated polyethyleneimine may have a high degree of branching, preferably the polyalkoxylated polyethyleneimine is hyperbranched. As used herein, the term “hyperbranched” refers to highly branched polymers that typically exhibit a globular structure. Hyperbranched polymers typically exhibit substantial irregularity in terms of branching pattern and structure, which typically results in substantial variation in molecular weight (often referred to as polydispersity). One useful measure for assessing the amount of branching present in a polymer is the degree of branching. As used herein, the term “degree of branching” refers to the ratio of (a) the total number of branch repeat units included in a polymer to (b) the total number of repeat units included in the polymer. Hyperbranched polymers having any suitable degree of branching may be employed in compositions described herein. In certain embodiments, the hyperbranched polymers exhibit a degree of branching of at least about 4 to 20 monomer units per molecule. Care should generally be exercised in interpreting degree of branching information for hyperbranched polymers. For example, certain hyperbranched polymers may exhibit a degree of branching of less than about 0.2 yet include one or more hyperbranched polymer portions (or subunits) that exhibit a degree of branching of greater than about 0.2. This may be the case, for example, when a hyperbranched polymer core is chain extended using long chains of linear repeat units. If sufficiently chain extended, the overall degree of branching for such a polymer may be less than about 0.2.

The mass average molecular mass M_w of the polyal koxylated polyalkyleneimine may be of from about 500 g/mol to about 500 000 g/mol. The lower limit of the weight average molecular mass M_wof the polyalkoxylated polyalkyleneimine is generally about 1500 g/mol, preferably about 2500 g/mol, more preferably about 5000 g/mol. The upper limit of the weight average molecular mass M_w is generally about 500 000 g/mol, preferably about 150 000 g/mol, more preferably about 50 000 g/mol, most preferably about 25 000 g/mol. A particularly preferred range is of from 800 to 25000 g/mol, most particularly 5000 to 25000 g/mol. The molecular mass may be determined by size exclusion chromatography like GPC using polymethylmethacrylate (PMMA) as standard and hexafluorisopropanol + 0.05% potassium trifluoracetate as eluent.

The average number of oxyalkylene units in the polyoxyalkylene group may be of from 1 to about 30 per N-hydrogen atom in the polyalkyleneimine, preferably 2 to 25, more preferably 3 to 20, most preferably 5 to 15.

The polyalkoxylated polyalkyleneimine may be present in an amount of from about 0.01 to about 1 % by weight, preferably from about 0.012 to about 0.8 % by weight, more preferably from about 0.15 to about 0.6 % by weight, even more preferably from about 0.02 to about 0.5 % by weight, most preferably from about 0.02 to about 0.3 % by weight. It was found that amounts of polyalkoxylated polyalkyleneimine lower than 0.01 wt.% are insufficient to increase the cleaning performance of the composition. On the other hand, further increase of the concentration is beyond 1 wt.% is possible but does not improve the performance anymore. Additionally, since a number of components are involved to obtain the composition, a fine balance is typically needed to ensure colloidal stability. Here, the presence of a high amount (beyond 1 wt.%) of a (polymeric) component such as polyalkoxylated polyethyleneimine may be detrimental to the long-term stability of the multi-component system, especially in substantially aqueous medium. Chelating agents

The cleaning composition may optionally comprise one or more chelating agents.

Preferred chelating agents are of 1,2-cyclohexylenedinitrilotetraacetic acid, 1,1 , 1 ,5, 5, 5- hexafluoro-2,4-pentane-dione, acetylacetonate, 2,2’-azanediyldiacetic acid, ethylenediamine- tetra-acetic acid, etidronic acid, methanesulfonic acid, acetylacetone, 1 , 1 , 1 -trifluoro-2,4- pentanedione, 1,4-benzoquinone, 8-hydroxyquinoline, salicyli-dene aniline; tetrachloro-1,4- benzoquinone, 2-(2-hydroxyphenyl)-benzoxazol, 2-(2-hydroxyphenyl)-benzothiazole, hydroxyquinoline sulfonic acid, sulfosali-cylic acid, salicylic acid, pyridine, 2-ethylpyridine, 2- methoxypyridine, 3-methoxypyridine, 2-picoline, dimethylpyridine, piperidine, piperazine, ethylamine, methylamine, isobutylamine, tert-butylamine, tributylamine, dipropylamine, dimethylamine, diglycol amine, methyldiethanolamine, pyrrole, isoxazole, bipyridine, pyrimidine, pyrazine, pyridazine, quinoline, isoquinoline, indole, 1 -methylimidazole, diisopropylamine, diisobutylamine, aniline, pentamethyldi-ethylenetriamine, acetoacetamide, ammonium carbamate, ammonium pyrrolidinedithiocarbamate, dimethyl malonate, methyl acetoacetate, N-methyl acetoacetamide, tetramethylammonium thiobenzoate, 2, 2,6,6- tetramethyl-3,5-heptanedione, tetramethylthiuram disulfide, lactic acid, ammonium lactate, formic acid, propionic acid, gamma-butyrolactone, and mixtures thereof;

The chelating agent may be 1,2-cyclohexylenedinitrilotetraacetic acid (CDTA) or may comprise CDTA as well as one or more of the other chelating agents above.

A composition according to the invention as defined herein is also preferred wherein the amount of the one or more chelating agents present is of from about 0.01 to about 4 % by weight, preferably of from about 0.02 to about 1 % by weight, more preferably of from about 0.05 to about 0.8 % by weight, based on the total weight of the composition.

Surfactants

The composition may also further comprise one or more surfactants.

Preferred surfactants are selected from the group consisting of

(i) anionic surfactants, preferably selected from the group consisting of ammonium lauryl sulfate, fluorosurfactants, preferably selected from the group consisting of perfluorinated alkylsulfonamide salts (preferably perfluorinated, N-substituted alkylsulfonamide ammonium salts, PNAAS), perfluorooctanesulfonate, perfluorobutanesulfonate, perfluorononanoate and perfluorooctanoate; alkyl-aryl ether phosphates and alkyl ether phosphates; (ii) zwitterionic surfactants, preferably selected from the group consisting of (3-[(3- cholamidopropyl)dimethylammonio]-1 -propanesulfonate) (“CHAPS”), cocamidopropyl hydroxysultaine (CAS RN 68139-30-0), {[3-(dodecanoylamino)propyl](dimethyl)- ammoniojacetate, phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine; and

(iii) non-ionic surfactants, preferably selected from the group consisting of glucoside alkyl ethers, glycerol alkyl ethers, cocamide ethanolamines and lauryldimethylaminoxide.

More preferred surfactants in compositions according to the invention are or comprise perfluorinated, N-substituted alkylsulfonamide ammonium salts. Preferred surfactants (E) in compositions according to the invention do not comprise metals or metal ions.

A composition according to the invention as defined herein is also preferred wherein the amount of the one or more surfactants of the surfactant present is of from about 0.0001 to about 1 % by weight, preferably of from about 0.0005 to about 0.5 % by weight, more preferably in an amount of from about 0.001 to about 0.01 % by weight, based on the total weight of the composition.

Specific surfactants for use in the compositions described herein include, but not limited to, bis(2-ethylhexyl)phosphate, perfluoroheptanoic acid, prefluorodecanoic acid, trifluoromethanesulfonic acid, phosphonoacetic acid, dodecenylsuccinic acid, dioctadecyl hydrogen phosphate, octadecyl dihydrogen phosphate, dodecylamine, dodecenylsuccinic acid monodiethanol amide, lauric acid, palmitic acid, oleic acid, juniperic acid, 12 hydroxystearic acid and dodecyl phosphate; polyoxyethylene lauryl ether (Emalmin NL-100 (Sanyo), Brij 30, Brij 98, Brij 35), dodecenylsuccinic acid monodiethanol amide (DSDA, Sanyo), ethylenediamine tetrakis(ethoxylate-block-propoxylate) tetrol (Tetronic 90R4), polyethylene glycols (e.g., PEG 400), polypropylene glycols, polyethylene or polypropylene glycol ethers, block copolymers based on ethylene oxide and propylene oxide (Newpole PE-68 (Sanyo), Pluronic L31 , Pluronic 31 R1 , Pluronic L61 , Pluronic F-127) (Dynol 607), polyoxypropylene sucrose ether (SN008S, Sanyo), t-octylphenoxypolyethoxyethanol (Triton X100), 10-ethoxy-9,9-dimethyldecan-1 -amine (TRITON® CF-32), Polyoxyethylene (9) nonylphenylether, branched (IGEPAL CO-250), polyoxyethylene (40) nonylphenylether, branched (IGEPAL CO-890), polyoxyethylene sorbitol hexaoleate, polyoxyethylene sorbitol tetraoleate, polyethylene glycol sorbitan monooleate (Tween 80), sorbitan monooleate (Span 80), a combination of Tween 80 and Span 80, alcohol alkoxylates (e.g., Plurafac RA-20), alkyl-polyglucoside, ethyl perfluorobutyrate, 1, 1,3, 3,5,5- hexamethyl-1 ,5-bis[2-(5-norbornen-2-yl)ethyl]trisiloxane, monomeric octadecylsilane derivatives such as SIS6952.0 (Siliclad, Gelest), siloxane modified polysilazane such as PP1-SG10 Siliclad Glide 10 (Gelest), silicone-polyether copolymers such as Silwet L-77 (Setre Chemical Company), Silwet ECO Spreader Momentive), and ethoxylated fluorosurfactants (ZONYL® FSO-100, ZONYL® FSN-100); cetyl trimethylammonium bromide (CTAB), heptadecanefluorooctane sulfonic acid, tetraethylammonium, stearyl trimethylammonium chloride (Econol TMS-28, Sanyo), 4-(4-diethylaminophenylazo)-1-(4-nitrobenzyl)pyridium bromide, cetylpyridinium chloride monohydrate, benzalkonium chloride, benzethonium chloride benzyldimethyldodecylammonium chloride, benzyldimethylhexadecylammonium chloride, hexadecyltrimethyl- ammonium bromide, dimethyldioctadecylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium p-toluenesulfonate, didodecyldimethylammonium bromide, dehydrogenated tallow) dimethylammonium chloride, tetraheptylammonium bromide, tetrakis(decyl)ammonium bromide, Aliquat® 336 and oxyphenonium bromide, guanidine hydrochloride (C(NH2)3CI) or tritiate salts such as tetrabutylammonium trifluoromethanesulfonate, dimethyldioctadecylammonium chloride, dimethyldihexadecylammonium bromide and dehydrogenated tallow)dimethylammonium chloride (e.g., Arquad 2HT-75, Akzo Nobel), bromide-containing surfactants, such as, 1 -hexadecyltrimethylammonium bromide.

In some embodiments the compositions of this invention will be free of or substantially free of any or all of the above-listed surfactants.

Composition

Other commonly known components such as dyes, chemical modifiers, biocides, etc. can be included in the cleaning composition in conventional amounts, for example, amounts up to a total of about 1 or 5 or 10 % by weight of the composition to the extent that they do not adversely affect the performance of the composition.

Alternatively, the cleaning compositions may be free or substantially free of any or all of dyes, chemical modifiers, biocides.

The cleaning composition is typically prepared by mixing the components together in a vessel at room temperature until all solids have dissolved in the aqueous-based medium.

Generally, the pH of the composition may be in the range of from 8 to 14. In a preferred embodiment the pH of the etching composition is from about 9 to about 13, more preferably from about 10 to about 13, most preferably from about 11 to about 12.5.

A cleaning composition is specifically preferred wherein the composition comprises or essentially consists of:

(a) 10 to 60 % by weight of a water-miscible aprotic organic solvent, particularly a sulfoxide or a sulfone, most particularly dimethylsulfoxide or sulfolane;

(b) 4 to 15 % by weight of a C1-C12 amine, particularly an alkanolamine, most particularly 2- (methylamino)ethan-l-ol;,

(c) 0.5 to 4 % by weight of a C4 to C16 quaternary ammonium hydroxide, particularly a C4 to Cs quaternary ammonium hydroxide, most particularly tetramethyl ammonium hydroxide or tetraethyl ammonium hydroxide;

(d) 0.1 to 5 % by weight of a C2 to C10 polyol, particularly a compound of formula HOCH2(CHOH)kCH2OH, wherein k is 0 or an integer of from 1 to 8, most particularly sorbitol, ethylene glycol or a mixture thereof; (e) 0.01 to 3 % by weight of a polyethyleneimine, particularly an unsubstituted polyethyleneimine, most particularly a polyethyleneimine having a mass average molecular mass of from 600 to 50 000 g/mol;

(f) water;

(g) optionally 0.01 to 2 % by weight of a polyalkoxylated polyethyleneimine, particularly a polyethyleneimine that is polyalkoxylated, particularly polyethoxylated, with 5 to 15 per N- H group; and

Another cleaning composition is specifically preferred wherein the composition comprises or essentially consists of:

(a) 20 to 50 % by weight of a water-miscible aprotic organic solvent;

(b) 7 to 13 % by weight of an amine;

(c) 1 to 3 % by weight of a quaternary ammonium hydroxide;

(d) 1 to 3 % by weight of a C2 to C10 polyol;

(e) 0.02 to 3 % by weight of a polyethyleneimine;

(f) water; and

(g) optionally a polyalkoxylated polyethyleneimine.

It is preferred that the amine is different from the water-miscible organic solvent and the polyol and/or that the water-miscible organic solvent is different from the amine and the polyol and/or that the polyol is different from the amine and the water-miscible organic solvent. It is particularly preferred that all components of the composition are different compounds.

“Essentially” in this context means that the content of any other compounds except the specifically mentioned ones are below 1 % by weight, preferably below 0.1 % by weight, even more preferably below 0.01 % by weight, most preferably below the detection limit.

A composition according to the invention as defined herein is specifically preferred wherein the composition consists of the compounds as defined herein and to be defined based on the examples. All components in the compositions add up to 100 % by weight of the whole composition.

Application

In another aspect there is provided a process of removing post etch residues from a substrate, the substrate comprising a surface of a molybdenum layer, the process comprising:

(b) providing a composition as described herein;

(c) contacting the surface with the composition for a time and at a temperature effective to remove the post etch residues while not compromizing the molybdenum layer. Without limitation, such layers may be present conducting lines of semidamascene structures.

It will be appreciated that it is common practice to make concentrated forms of the compositions to be diluted prior to use. For example, the compositions may be manufactured in a more concentrated form and thereafter diluted with water or other components at the manufacturer, before use, and/or during use.

In the use of the compositions described herein, the composition typically is contacted with the device structure for a sufficient time of from about 1 minute to about 200 minutes, preferably about 1 minute to about 10 minutes, at temperature in a range of from about 30 °C to about 90 °C, preferably about 35 °C to about 60 °C. Such contacting times and temperatures are illustrative, and any other suitable time and temperature conditions may be employed that are efficacious to achieve the required removal selectivity.

Following the achievement of the desired etching action, the composition can be readily removed from the microelectronic device to which it has previously been applied, e.g., by rinse, wash, or other removal step(s), as may be desired and efficacious in a given end use application of the compositions of the present invention. For example, the device may be rinsed with a rinse solution including deionized water, an organic solvent, and/or dried (e.g., spin-dry, N2, vapor-dry etc.).

Preferably the Mo etch rates of the compositions are 7 A/min or below.

After the contacting step is an optional rinsing step. The rinsing step may be carried out by any suitable means, for example, rinsing the substrate with de-ionized water by immersion or spray techniques. In preferred embodiments, the rinsing step may be carried out employing a mixture of de-ionized water and an organic solvent such as, for example, isopropanol.

After the contacting step and the optional rinsing step is an optional drying step that is carried out by any suitable means, for example, isopropanol (I PA) vapor drying, heat, or by centripetal force.

The etching composition described herein may be advantagoulsy used in a process for the manufacture of a semiconductor device, comprising the step of selectively reving post etch residues from a surface of a microelectronic device comprising a molybdenum layer as described herein.

The following examples shall further illustrate the present invention without restricting the scope of this invention. Examples

Etching experiments were conducted on blanket and semi-damascene coupons comprising a PVD Mo layer with a thickness of 47.5 nm as follows.

100 ml of etching solution was placed into a 150 ml beaker and the beaker was placed into a temperature-controlled water bath. A 2.5 cm x 2.5 cm coupon of the respective substrate was then dipped into the test solution at desired temperature while the solutions was stirred with a 250-rpm speed. Both blanket and semi-damascene coupon etching were carried out 2 min followed by DIW rinsing for 30 seconds and then the coupons were dried with an N2 gun. The blanket coupon etching experiments were carried out at 40°C and 60°C whereas semidamascene etching experiments at 40°C.

The thickness of the blanket coupons was determined by XRF measurements. The semidamascene coupons were characterized with TEM.

The etching rates were calculated according to the following formula:

Example 1

100 g of the semi-aqueous solution with Mo inhibitor was prepared by adding the following components in the specified order:

1. 49.5 g of DIW

2. 34 g of DMSO (from BASF)

3. 10.3 g of 2-methylethanolamine (from ACROS)

4. 1 g of ethylene glycol (from BASF)

5. 4 g of 25 wt.% TMAH solution in DIW (from BASF)

6. 0.6 g of sorbitol (from BASF)

7. 0.025 g of an acrylic acid-functionalized polyethoxylated PEI (M_w=25 000 g/mol) with an average of 10 EO per N-H group (from BASF), further referred to as “polyethoxylated PEI”

8. 0.025 g of a PEI (M_w=2 000 g/mol) (from BASF)

The solution was stirred with a magnetic stirring bar with a speed of 100 rpm during the mixing. The solutions with different Mo inhibitor concentration and different M_w of PEI were prepared in the same order as above and the amount of DI W was be adapted to reach the desired Mo inhibitor concentration. The Mo etching rate (ER) of solutions with different concentrations of polyethyleneimine (PEI) with a mass averagage molar mass M_w of 2000 g/mol at 40 °C and 60 °C was determined on blanked coupons. The compositions and results are depicted in table 1.

Table 1

Comparative example C1.1 that does not comprise any Mo inhibitor results in a higher Mo etching rate than any formulation which comprises PEI at different concentrations. Comparative example C1.3 comprising 0.005 wt.% PEI has no Mo etch inhibiting effect compared to comparative example C1.1 without PEI indicating that the inhibitor concentration is not sufficient to protect Mo surface. PEI Concentrations of 1 % by weight may be used but show a slightly lower corrosion inhibiting effect. Example 2

The Mo etching rate (ER) of solutions with different molecular masses of polyethyleneimine (PEI) was determined at 40 °C and 60 °C on blanked coupons. The results are depicted in table 2.

Table 2

The results how that all solutions with PEI of different molecular masses all show a reduced etching of Mo.

Example 3

A 32 nm metal pitch semi-damascene dry-etched test structure (from IMEC) as schematically depicted in Fig. 1 were treated with the cleaning compositions C1.1 and 1.4. The post etch residues were on the surface of the respective layers.

The substrates were inspected by TEM. As can be derived from Figs. 2 and 3, in contrast to the composition C1.1 (Fig. 2) composition 1.4 (Fig. 3) leads to a much better removal of the post etch residues, particularly at the bottom of the lines while not attacking the Mo lines themselves.

Claims

1. A composition for removing post etch residues from a substrate, the substrate comprising a surface of a molybdenum layer, the composition comprising:

(a) 10 to 60 % by weight of a water-miscible organic solvent;

(b) 4 to 15 % by weight of a C1-C12 amine;

(c) 0.5 to 4 % by weight of a C4 to C16 quaternary ammonium hydroxide;

(d) 0.1 to 5 % by weight of a C2 to C10 polyol;

(e) 0.01 to 3 % by weight of a polyethyleneimine; and

(f) water.

2. The composition according to anyone of the preceding claims, wherein the organic solvent is a sulfur-containing aprotic organic solvent, particularly from a sulfoxide and a sulfone.

3. The composition according to claim 2, wherein organic solvent is selected from dimethylsulfoxide, diethylsulfoxide, methylethyl-sulfoxide, dipropyl sulfoxide, and sulfolane.

4. The composition according to anyone of the preceding claims, wherein the amine is selected from a Ci to C10 alkylamine and a C2 to C10 alkanolamine.

5. The composition according to claim 4, wherein the amine is selected from 2- methylethanolamine.

6. The composition according to anyone of the preceding claims, wherein the quaternary ammonium hydroxide is selected from a C4 to Cs alkyl quaternary ammonium hydroxide, particularly from tetramethylammonium hydroxide and tetraethylammonium hydroxide.

7. The composition according to anyone of the preceding claims, wherein the C2 to C10 polyol is selected from a compound of formula HOCH2(CHOH)kCH2OH, wherein k is 0 or an integer of from 1 to 8.

8. The composition according to anyone of claims 1 to 6, wherein the C2 to C10 polyol is selected from ethylene glycol, glycerol, erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol, galactitol, fucitol, iditol, inositol, volemitol, propylene glycol, 1,4-butanediol diethylene glycol, and a combination thereof.

9. The composition according to anyone of the preceding claims, wherein the polyethyleneimine has a mass average molecular mass of from 600 to 50 000 g/mol, preferably of from 800 to 25.000 g/mol.

10. The composition according to anyone of the preceding claims, wherein the polyethyleneimine is unsubstituted.

11. The composition according to anyone of the preceding claims, further comprising a polyalkoxylated polyethyleneimine.

12. The composition according to anyone of the preceding claims, having a pH of from 10 to 13, preferably of from 11 to 12.5.

13. The composition according to anyone of the preceding claims, essentially consisting of:

(a) 20 to 50 % by weight of a water-miscible organic solvent;

(b) 7 to 13 % by weight of an amine;

(c) 1 to 3 % by weight of a quaternary ammonium hydroxide;

(d) 1 to 3 % by weight of a C2 to C10 polyol;

(e) 0.02 to 3 % by weight of a polyethyleneimine;

(f) water; and

(g) optionally a polyalkoxylated polyethyleneimine.

14. Use of a composition according to anyone of the preceding claims for removing post etch residues from a semiconductor substrate comprising a surface of a molybdenum layer.

15. A process of removing post etch residues from a substrate, the substrate comprising a surface of a molybdenum layer, the composition comprising:

(b) providing a composition according to anyone of claim 1 to 13;