TWI399426B - Removal of Residue Removal from Semiconductor Dry Process and Residue Removal Method - Google Patents

Description

Residue removal liquid after semiconductor dry process and residue removal method using same

The present invention relates to a chemical liquid for removing a residue formed during dry etching and/or ashing in a semiconductor element manufacturing step, and a semiconductor element manufacturing method for removing the residue using the chemical liquid. In particular, it relates to a residue removing liquid used in the production of a Cu/low-k multilayer wiring structure.

In the past, a semiconductor element having an Al/SiO ₂ multilayer wiring structure in which an SiO ₂ film is an interlayer insulating film is used as a wiring material, such as Al or an Al alloy. In recent years, with the miniaturization of semiconductor elements to reduce the wiring delay, Cu/low- is used to fabricate a low-resistance wiring material Cu and an interlayer insulating film low-k film (low dielectric film) having a small capacitance between wirings. k multilayer wiring structure.

In the Cu/low-k multilayer wiring structure, processing is performed in a method called a damascene structure. According to this processing method, grooves (grooves) and holes (via holes) can be processed on the interlayer insulating film substrate, and a wiring material such as Cu is buried in the processed portion to form a wiring structure.

Further, in a method called a dual damascene structure, a trench for wiring and a via hole are formed by connecting an interlayer insulating film substrate formed of a low-k film or the like, and then a wiring material such as Cu is buried. In the case of forming a dual damascene structure, there is a process of first etching a via hole after forming a via hole and then forming a trench for wiring, and a Trench First process for forming a via hole after forming a trench for wiring in the reverse order described above. , and other Middle First processes and Dual Hard-Mask.

For example, in the process of etching the via hole first, the via hole is formed by dry etching on the interlayer insulating film substrate, and then the buried agent is buried and planarized. Dry etching of the lithography technique is performed to form the trench. Thereafter, the waste residue and the embedding agent are removed by ashing or the like from the substrate on which the grooves and the via holes are formed.

However, even after the process, waste which cannot be completely removed remains on the substrate (hereinafter referred to as "residue after dry process").

According to a dry process using dry etching, ashing, etc., Cu which is a wiring material and a low-k film which is an interlayer insulating film are damaged. Further, when the substrate is exposed to the atmosphere due to movement between processes or the like, a Cu oxide film is formed on the surface of the Cu metal wiring.

When a TaN which is a barrier metal and a metal such as Cu which is a wiring material are buried in the groove and the via hole of the damascene structure, if there is a residue after the dry process and a Cu oxide film, etc., it becomes a semiconductor element. Bad cause. Therefore, in general, the residues are removed using a polymer stripper. Further, the damaged low-k film is likely to cause a change in the size of the resist pattern when it is etched with a chemical liquid or the like because it is structurally weaker than originally. Therefore, when the residues are removed, it is necessary to use a chemical solution instead of causing corrosion of Cu, and to suppress etching of the low-k film.

When the residue after the dry process and the Cu oxide film are desirably removed by the conventional polymer stripping liquid and etching liquid which are currently commercially available, there is a problem in processing. For example, hydrochloric acid and hydrofluoric acid diluted with water can be used to remove the residue, but Cu is liable to cause corrosion due to a large amount of dissociated H ⁺ . Further, the interlayer insulating film (especially a gas-permeable low-k interlayer insulating film) which is damaged by the dry process may be deteriorated or may not be processed in accordance with the designed size.

Dry processes are also diversifying due to the miniaturization of component structures and the variety of low-k films. For example, a dry process is also used not only for the dry etching used in the conventional photoresist mask and the ashing used for the oxygen plasma, the dry etching of the hard mask, and the ashing used for the He/H ₂ plasma. Among these changes, it is sought not to cause damage to the Cu and low-k films, but to selectively remove the residue after the dry process and the Cu oxide film.

However, the low-k film is often damaged by the dry process, and is washed with a polymer stripping solution, which causes a change in the size of the photoresist pattern during etching. Further, the cleaning device for the semiconductor element is constantly changing from the batch type to the leaf type. Therefore, it is difficult to remove the residue after the dry process which strongly adheres to the Cu/low-k structure in a short time by using the method of the past stripping liquid. In addition, although corrosion of the Cu alloy due to washing was not observed, it was observed that cracks along the grain boundary of the Cu surface were often observed. Such cracks on the surface of the Cu surface have a great possibility of adversely affecting the performance of the component. Further, since the processed wafer is exposed to the atmosphere after the cleaning process, the Cu oxide film is also a cause of component defects.

When a conventional chemical solution such as hydrochloric acid or hydrofluoric acid is used in the formation of a Cu/low-k multilayer wiring structure, it is difficult to suppress corrosion of Cu and etching of a low-k film, and it is difficult to selectively remove residual residue and Cu after dry process. Oxide film.

In recent years, many polymer stripping solutions suitable for Cu/low-k multilayer wiring structures have been developed (for example, Patent Documents 1 to 4). However, with such polymer stripping liquids, it is difficult to prevent damage to the low-k film, and corrosion of Cu is suppressed, and the residue after the dry process can be completely removed in a short time. Further, it is difficult to suppress cracking of the Cu surface.

In view of the above circumstances, the present invention has an object of providing a chemical solution which can prevent cracking of Cu surface and which can suppress cracking of Cu surface, and can remove the residue after dry process in a short time. In addition, it is intended to provide a method of manufacturing a semiconductor device using the same.

Patent Document 1: Japanese Laid-Open Patent Publication No. Hei No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei.

The inventors of the present invention have found that by using an aqueous solution containing a strong acid, a polycarboxylate and water which form a complex or a chelating agent with Cu, the Cu and low-k film can be prevented from being damaged. Moreover, the crack on the Cu surface can be suppressed, and the residue strongly adhered after the dry process can be removed in a short time. Based on the relevant knowledge, and then added to the review, the present invention was completed.

That is, the present invention provides the following removal liquid of the residue on the semiconductor substrate after dry etching and/or ashing, and a method of manufacturing a semiconductor element using the residue removal liquid.

Item 1. A residue removing liquid which is a residue of a residue remaining on a semiconductor substrate after dry etching and/or ashing, and characterized in that it contains a strong acid or a polycarboxylic acid which forms a complex or a chelating agent with Cu. Salt and water.

Item 2. The residue removal liquid according to Item 1, wherein the strong acid which forms a complex or a chelating agent with Cu is Bronsted acid having a pKa of 3 or less at 25 °C.

Item 3. The residue removal solution according to Item 1 or 2, wherein the strong acid which forms a complex or a chelating agent with Cu is selected from the group consisting of trifluoroacetic acid, hydrobromic acid, perchloric acid, sulfuric acid, oxalic acid, and C. At least one of a group consisting of diacid and citric acid.

The residue removal liquid according to any one of items 1 to 3, wherein the polycarboxylate is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, malic acid, a base of at least one selected from the group consisting of tartaric acid, ammonium hydrogen citrate, and citric acid, and at least one selected from the group consisting of ammonia, hydroxylamine, primary, secondary, and tertiary amines, quaternary ammonium, and polyamine The salt formed.

The residue removal liquid according to any one of items 1 to 4, wherein the concentration of the strong acid which forms a complex or a chelating agent with Cu in the residue removal liquid is 0.1 to 5% by weight, and the concentration of the polycarboxylic acid It is 0.1 to 20% by weight.

Item 6. The residue removal solution according to any one of items 1 to 5, wherein the pH is from 4 to 6.5.

Item 7. The residue removal liquid according to any one of items 1 to 5, which further contains an organic compound.

Item 8. The residue removal liquid according to Item 7, wherein the organic compound is selected from the group consisting of polycarbonyls, hydroxyketones, esters, alcohols of C3 or higher, aldehydes of C3 or higher, polyethers and anthraquinones. At least one of the groups.

Item 9. The residue removal solution according to item 7 or 8, wherein the pH is 4-7.

The residue removal liquid according to any one of items 7 to 9, wherein the concentration of the strong acid which forms a complex or a chelating agent with Cu in the residue removal liquid is 0.1 to 5% by weight, and the polycarboxylate The concentration is 0.1 to 20% by weight, and the concentration of the organic compound is 0.5 to 60% by weight.

Item 11. The residue removal liquid according to any one of items 1 to 10, which further contains a fluorine compound.

Item 12. The residue removal solution according to Item 11, wherein the fluorine compound is hydrogen fluoride, or a fluoride salt of ammonia, hydroxylamine, primary, secondary or tertiary amine, quaternary ammonium or polyamine.

The residue removal liquid according to any one of items 1 to 12, which further contains a crack inhibitor of Cu and/or an oxidation inhibitor of Cu.

Item 14. A method for removing a residue, which is a method for removing a residue existing on a semiconductor substrate after dry etching and/or ashing, characterized by dry etching and/or ashing of a semiconductor substrate and items 1 to 13 The residue removal liquid of any of them is in contact.

Item 15. The method for removing a residue according to Item 14, which comprises copper as a wiring material and a semiconductor substrate having a low dielectric film (low-k film) as an interlayer insulating material.

Item 16. A method of manufacturing a semiconductor device, comprising: (1) having copper as a wiring material and having a low dielectric film (low-k film) as an interlayer insulating material; The step of dry etching and/or ashing the semiconductor substrate and (2) the step of bringing the semiconductor substrate after the above (1) treatment into contact with the residue removing liquid according to any one of items 1 to 13.

The invention is described in detail below.

Residue removal liquid after semiconductor dry process

The residue removing liquid of the present invention is characterized by containing a strong acid (hereinafter also referred to as "strong acid"), a polycarboxylate and water as a basic component which forms a complex or a chelating agent with Cu. Further, by adding an organic compound, a surfactant, a fluoride, a crack preventing agent, and an oxidizing agent, it is possible to add more excellent functions.

The object of the residue removal liquid of the present invention is mainly a Cu oxide film and a residue after a dry process.

The Cu oxide film may, for example, be a Cu oxide formed during dry etching and/or ashing, or a Cu natural oxide film which is naturally oxidized when exposed to the atmosphere due to movement between processes or the like. Most of its composition contains CuO, Cu ₂ O, Cu(OH) ₂ and the like.

The residue after the dry process is formed by using Cu as a conductive metal to form a film, which is a Cu oxide film on a Cu surface containing a Cu/low-k multilayer wiring structure, and/or dry etching and/or ash. It is composed of a Cu-deposited material of Cu oxide formed during the formation. The residue adheres to the side wall of the spectral pattern formed on the Cu wiring mainly forming the spectral pattern and the interlayer insulating film such as the low-k film, and the surface of the interlayer insulating film substrate. The residue formed on Cu is a spoiler residue composed of a mixture of oxidized and/or fluorinated Cu oxide and the Cu due to dry etching and/or ashing. Since the residue has a large electric resistance, an insulating layer is formed in the vicinity of the Cu oxide.

a residue attached to a side wall of a spectral pattern formed by an interlayer insulating film such as a low-k film, in addition to a Cu-deteriorated substance, and an insulating sensing film such as SiN and a low-k film, a buried agent, etc., are dry-etched. The latter may contain Si and organic matter. Further, it is presumed that the residue of the interlayer insulating film contains a photoresist which cannot be completely removed by ashing, and an organic substance such as an antireflection film and an embedding agent, and a residue obtained in the process using an inorganic mask. And some dry Si and Cu metamorphisms from the bottom of the trench and the via hole during dry etching.

In order to remove the residue after the dry etching process in a short time, the aforementioned strong acid, polycarboxylate and water are required. This reduces damage to the low-k film and also suppresses cracking of the minute Cu surface. Further, in order to prevent the cracking effect, it is preferred to use an ammonium salt of a polycarboxylic acid. When it is difficult to remove the residue adhering to the side wall of the spectral pattern formed by the interlayer insulating film such as a low-k film, the addition of an organic compound (particularly, a water-soluble organic compound) and a plurality of fluorine compounds can increase the removal effect. Further, in order to further increase the effect of causing cracks on the Cu surface, a crack preventing agent may be added. After removing the residue, if the oxide film on the surface of Cu is not increased, an oxidizing agent may be further added.

In the present specification, the interlayer insulating film mainly means a low-k film (low dielectric film), and also contains, for example, a fluorine-containing cerium oxide film (FSG film). The dielectric constant of the interlayer insulating film is generally more than 1,4 or less, preferably 3 or less, more preferably 2.8 or less, and most preferably 2.6 or less. The low-k film is mainly formed by coating or plasma CVD.

Specifically, the low-k film is made of LKD series (trade name, manufactured by JSR Corporation), HSG series (product name, manufactured by Hitachi Chemical Co., Ltd.), Nanoglass (product name, manufactured by Honeywell Co., Ltd.), and IPS (trade name, catalytic polymerization). Company system), Z ₃ M (trade name, manufactured by Dow Corning Co., Ltd.), XLK (trade name, manufactured by Dow Corning Co., Ltd.), FOx (trade name, manufactured by Dow Corning Co., Ltd.), Orion (trade name, manufactured by Tricon Co., Ltd.), NCS (trade name, manufactured by Catalyst Chemical Co., Ltd.), inorganic SOG film (HSG: hydrogenated silicate), and organic SOG film (MSQ: methyl-containing silicate) such as SiLK (trade name, manufactured by Dow Corning Co., Ltd.) A coating film (organic polymer film) containing a main component such as polyarylene ether, and Black Diamond (trade name, manufactured by Applied Materials Co., Ltd.), Coraru (trade name, manufactured by Novellus Co., Ltd.), and Ooraru (trade name, ASM) The plasma CVD film represented by the company) is not limited to these materials.

The spectral pattern may, for example, be a KrF, ArF or F ₂ spectral pattern, but is not limited to these. As the burying agent, an organic compound having both functions of an antireflection film can be used.

A strong acid which forms a complex or a chelating agent with Cu is a Brookfield acid having a pKa of 3 or less (more preferably 2 or less, preferably 0 to 2) having a hydrogen ion H ⁺ and Cu and a chelating agent or a mismatch. The structure (part) of the material also has the function of removing the residue after the dry process.

Specific examples thereof include halogenated carboxylic acid and hydrogen such as chloroacetic acid, dichloroacetic acid, trichloroacetic acid, α-chlorobutyric acid, β-chlorobutyric acid, γ-chlorobutyric acid, fluoroacetic acid, difluoroacetic acid, and trifluoroacetic acid. A mineral acid such as bromic acid, perchloric acid or sulfuric acid, a polycarboxylic acid such as oxalic acid, malonic acid, tartaric acid or citric acid. Among them, oxalic acid, malonic acid, citric acid, trifluoroacetic acid, hydrobromic acid, and perchloric acid are preferred, and oxalic acid, malonic acid, citric acid, and trifluoroacetic acid are more preferred.

The concentration of the strong acid in the residue removal liquid can be suitably selected in accordance with the quality and amount of the residue after the dry process to be removed. The concentration of the strong acid is generally 0.1 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight. The lower the concentration, the easier it is to remove the residue after the dry process, and the higher the concentration, the easier it is to remove. From the viewpoint of the cost effect, it is preferably 5% by weight or less.

The polycarboxylate can reduce the damage to the low-k film while preventing the corrosion of Cu by reacting with a strong acid, and has the effect of removing the residue after the dry process containing Cu. Particularly, the amine salt of polycarboxylic acid has an efficient inhibition of Cu surface cracking.

Examples of the polycarboxylate include a carboxylic acid such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, malic acid, tartaric acid, diammonium hydrogen citrate, ammonium dihydrogen citrate, and citric acid. A salt formed from a base such as an acid, an ammonium salt, a hydroxylamine, a primary, a secondary, a tertiary amine, a quaternary ammonium or a polyamine. Examples thereof include a polycarboxylic acid such as malonic acid, diammonium hydrogen citrate, ammonium dihydrogen citrate, and citric acid, and an alkali, a primary, a secondary, a tertiary amine, a quaternary ammonium, and a polyamine. The salt formed is preferred.

More specifically, an ammonium salt such as malonic acid, diammonium hydrogen citrate, ammonium dihydrogen citrate or polycarboxylic acid such as citric acid, a methylamine salt, an ethylamine salt, a propylamine salt or a butyl group may be mentioned. Amine salt, dimethylamine salt, diethylamine salt, trimethylamine salt, triethylamine salt, propylenediamine salt, triethylenetetramine salt, tetramethylammonium hydroxide salt, choline salt, etc. .

Among them, ammonium salt of malonic acid, methylamine salt, ethylamine salt, tetramethylammonium hydroxide or choline salt; methylamine salt of diammonium hydrogen citrate, ethylamine salt, and hydrogen hydroxide a methylammonium salt or a choline salt; a methylamine salt of an ammonium dihydrogen citrate, an ethylamine salt, a tetramethylammonium hydroxide salt or a choline salt; and a tetramethylammonium hydroxide salt or a choline salt For the best.

The polycarboxylate can be used in the form of a crystal, and an aqueous solution obtained by mixing and neutralizing the above-mentioned acid and base in water can also be used. In the residue removal liquid, the concentration of the polycarboxylate is generally 0.1 to 20% by weight, preferably 0.5 to 10% by weight, and most preferably 1 to 5% by weight.

It is preferable that the molar ratio of the strong acid which can form a complex or a chelating agent to Cu is 0.3 to 1 with respect to the polycarboxylate contained in the residue removing liquid, and 0.35 to 0.8 is more preferable. . When the ratio is less than 0.3, Cu is liable to cause corrosion. When it exceeds 1, the ability to remove the residue after the dry process tends to be reduced.

In the residue removal liquid of the present invention, an organic compound (particularly a water-soluble organic compound) may be further added. The organic compound can reduce the corrosion of Cu caused by a strong acid, and the residue adhered to the side wall of the spectral pattern formed by the interlayer insulating film such as a low-k film, and the surface residue of the interlayer insulating film substrate, and the like after the dry process. Gives removal effect.

The organic compound may, for example, be a hydrophilic or water-soluble neutral organic compound, such as a polycarbonyl group, a hydroxyketone, an ester, an alcohol having C3 or higher, an aldehyde having a C3 or higher, a polyether or an anthracene.

Examples of the polycarbonyl group include 2,3-butanedione, 2,4-pentanedione, methylglyoxal, and ethylacetone. It is preferred to use 2,3-butanedione or 2,4-pentanedione.

Examples of the hydroxyketones include acetamethanol, acetol, diacetone alcohol and the like. Ethyl acetate and acetol are preferred.

Examples of the esters include monocarboxylic acid esters such as methyl acetate, ethyl acetate, methyl propionate, and ethyl propionate; dimethyl oxalate, diethyl oxalate, dimethyl malonate, and C. a polycarboxylate such as diethyl diacrylate or dimethyl succinate; a carbonate such as dimethyl carbonate or diethyl carbonate; a cyclic ester such as propylene carbonate, ethylene carbonate or γ-butyrolactone; Ketone esters such as ethyl acetate, ethyl acetate and ethyl acetate; oxyesters such as methyl lactate, ethyl lactate and butyl lactate; ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol Mono-n-butyl ether acetate, diethylene glycol methyl ether acetate, diethylene glycol diethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, ethylene glycol diacetate (ethylene diacetate), propylene glycol methyl ether An alkoxylate such as acetate (PGMEA) or propylene glycol diethyl ether acetate. Examples thereof include propylene carbonate, γ-butyrolactone, ethanediacetic acid, PGMEA, methyl acetacetate, ethyl acetate, ethyl lactate, and the like.

Examples of the aldehyde of C3 or higher include a hydrophobic group-containing alcohol such as a long-chain (for example, C3-6) alkyl group such as isopropyl alcohol, 1-butanol, tert-butanol or isobutanol; Glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, poly(propylene glycol), glycerin, 2-amino-2-ethyl-1,3-propanediol, 2-amino group -2-methyl-1,3-propanediol, 1,2-cyclohexanol, 2,2-dimethyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanol , 2,3-naphthalenediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-butyl-1,4-diol, 2-butene- 1,4-diol, 1,3-propanediol, 1,2-propanediol, DL-1,2-hexylhexaol, 2,5-hexahexaol, 1,2-benzenediol, 2,4-pentyl Polyols such as diol and 2-methyl-2,4-pentanediol; ethylene glycol methyl ether, ethylene glycol ether, ethylene glycol mono-n-butyl ether, ethylene glycol phenyl ether, diethylene glycol methyl ether , diethylene glycol ether, diethylene glycol isobutyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol benzyl ether, diethylene glycol hexyl ether, diethylene glycol benzyl ether, triethylene glycol Ether, triethylene glycol butyl ether, three Glycol methyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol mono-n-dodecyl ether, heptaethylene glycol mono-n-dodecyl ether, polyethylene glycol ether, alkyl alcohol. The isopropyl alcohol, 1-butanol, isobutanol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol or the like is preferably used.

Examples of the aldehyde of C3 or higher include propionaldehyde, butyraldehyde, valeraldehyde and the like.

Examples of the polyether include dimethoxymethane, diethoxymethane, dimethoxyethane, dimethoxypropane, ethylene glycol dimethyl ether, and ethylene glycol dimethyl ethyl ether. Ethylene glycol diethyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol n-Butyl ether, triethylene glycol dimethyl ether, triethylene glycol ethyl methyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether , polyethylene glycol dimethyl ether and the like. Among them, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether are preferred.

Examples of the oxime include, for example, cyclobutyl hydrazine, dimethyl hydrazine, and the like.

Among the above organic compounds, 2,3-butanedione, 2,4-pentanedione, acetamyl methylmethanol, propylene carbonate, γ-butyrolactone, ethylene glycol diacetate (ethylene diacetate) ), propylene glycol methyl ether acetate (PGMEA), isopropanol, n-butanol, isobutanol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, ethylene glycol monobutyl ether, ethylene Alcohol methyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, B Methyl hydrazine acetate, ethyl acetate ethyl acetate, ethyl lactate are suitable.

The concentration of the organic compound in the residue removing liquid is generally 60% by weight or less, preferably 0.5 to 60% by weight, more preferably 2 to 40% by weight, and most preferably 3 to 30% by weight.

Further, a fluorine compound may be added to the residue removing liquid, thereby improving the effect of removing the residue adhering to the side wall of the spectral pattern formed by the interlayer insulating film such as the low-k film. In addition to the Cu-degraded material, the residue may have an insulating sensing film such as SiN or a low-k film, and the underfill may be sputter-plated by dry etching, and may contain Si and an organic substance. However, even if the residue contains Si and an organic substance, when the Cu oxide is a main constituent, it is generally removed without adding a fluorine compound. An interlayer insulating film such as a low-k film which is subjected to plasma damage in a dry process cannot be easily etched by a fluorine compound, and processing such as design size cannot be performed. Therefore, when the residue cannot be sufficiently removed, and it is not possible to determine whether or not to remove the residue, a higher removal effect is given, and it is preferable to add a small amount of a fluorine compound.

The fluorine compound may, for example, be a fluoride salt such as hydrogen fluoride or ammonia, a hydroxylamine, a primary, secondary or tertiary amine, a quaternary ammonium or a polyamine. Specifically, hydrogen fluoride, ammonium fluoride, ammonium monohydrogen difluoride, methyl fluoride, fluorinated ethylamine, diethylamine fluoride, triethylenetetramine fluoride, tetramethylammonium fluoride, etc. It is better. One type or two or more types of fluorine compounds can be used. One embodiment of the present invention can be used, for example, as an aqueous solution of ammonium fluoride or a dilute hydrofluoric acid (50% by weight aqueous solution).

The concentration of the fluorine compound in the residue removal liquid can be appropriately selected in accordance with the type of the interlayer insulating film containing the ruthenium dioxide film, the low-k film, and the interlayer insulating film which is subjected to the plasma damage in the dry process. The concentration of the fluorine compound is preferably 5% by weight or less, more preferably 0.001 to 5% by weight, and most preferably 0.01 to 3% by weight.

When it is necessary to suppress etching of the interlayer insulating film from the plasma damage portion, it is preferred that the residue removing liquid contain no fluorine-containing compound or a small amount (1% by weight or less). When the concentration is less than 0.001% by weight, the effect of removing the residue is reduced.

Further, a surfactant may be added to the residue removing liquid of the present invention. The surfactant can increase the wettability of the hydrophobic interlayer insulating film, and can uniformly distribute the chemical solution according to the shape of the spectral pattern. The type thereof is not particularly limited to a cationic system, an anionic system, or a neutral system. The concentration of the surfactant in the residue removing liquid is preferably 0.00001 to 5% by weight, more preferably 0.0001 to 3% by weight. When the amount is less than 0.00001% by weight, the effect of the surfactant is too small, and when it is more than 5% by weight, there is no effect change.

Further, a crack preventing agent may be added to the residue removing liquid of the present invention. The crack preventing agent may be a sulfur-containing compound having an unrecognized electron oxygen atom and/or a nitrogen atom having a non-shared electron, and having a non-shared electron, and may be exemplified by a sulfide, a mercaptan, a sulfuric acid, or a sulfur. At least one of a group of acetaminophens, thioureas, thiadiazolines, tetrazoles, triazines, thiazoles, thiophenes, pyrimidines, anthraquinones, thiazolines, and tetrahydroazoles Contains sulfur compounds. Specifically, a compound as described below can be exemplified.

The sulfide may, for example, be thiodiglycol, 2,2'-thioacetic acid or 3,3'-dithiopropionic acid.

The mercaptan may, for example, be thiohydroacetic acid, thiomalic acid, thiolactic acid, 3-thiohydropropionic acid, thiophenol, 2-thiolethanol, 3-sulfhydryl-1,2-propane. Glycol and the like.

Examples of the sulfur carboxylic acid include mercaptan acetate, 3-ethylsulfonyl-2-methylpropionic acid, and the like.

Examples of the thioacetamides include thioacetamide and the like.

Examples of the thiourea include thiourea, dithiosemicarbazide, thiol thiourea, ethylene thiourea, and malonic acid thiourea.

Examples of the thiadiazolines include 2,5-dithiohydrogen-1,3,4-thiadiazole, 2-thioacetic acid-5-sulfato-1,3,4-thiadiazole, 2,5-dithioacetic acid-1,3,4-thiadiazole and the like.

Examples of the tetrazole include 1-methyl-5-sulfato-1H-tetrazole.

Examples of the triazines include 2,4,6-trisulhydro-s-triazine and the like.

Examples of the thiazoles include 4-azolecarboxylic acid and 2-aminoazole.

Examples of the thiophene include 2,5-thiophene dicarboxylic acid, 3-thiophene malonic acid, 2-thiophenecarboxylic acid, and the like.

Examples of the pyrimidines include 2-thiobarbituric acid, 2-thiopyrimidine, thiouracil, 4-amino-6-hydroxy-2-thiolpyrimidine, and the like.

Examples of the oxime include 2,5-dithioanthracene, 6-sulfatohydrazine and the like.

Examples of the thiazoline include 2-amino-2-thiazoline and 2-thiazolin-2-thiol.

Examples of the tetrahydroazoles include 2,4-sulfazinedione, 2-thio-4-tetrazole, 2-imino-4-thiazolidine and the like.

In the present invention, the crack preventing agent can be used for supplementation, and the concentration thereof is preferably, for example, 0.00001 to 3% by weight, more preferably 0.00005 to 1% by weight.

In the residue removing liquid of the present invention, an oxidizing agent may be further added. The antioxidant may, for example, be benzotriazole or the like. The concentration is preferably, for example, 0.00001 to 3% by weight, more preferably 0.0005 to 1% by weight.

The proportion of the water contained in the residue removing liquid of the present invention is generally 40 to 99.5% by weight, preferably 70 to 99% by weight, based on the amount (concentration) of the components other than water. .

The pH of the removal liquid of the present invention is 4-7. The surface of the low-k film damaged in the dry process is prone to deterioration when it is less than 4. When it exceeds 7, Cu is easily corroded. The pH is preferably 4 to 6.5. The pH can be adjusted depending on the amount of the strong acid and the carboxylic acid and the amount of the organic compound required.

For example, it contains a strong acid which can form a complex or a chelating agent with Cu, a polycarboxylate and a residue of water, and the concentration of the strong acid is 0.1 to 5% by weight (preferably 0.3 to 3% by weight), and the polycarboxylate The concentration is 0.1 to 20% by weight (0.5 to 10% by weight is preferred). The pH is 4 to 6.5 (pH is preferably 4 to 6). The strong acid molar ratio relative to the polycarboxylate is 0.3 to 1 (0.35 to 0.8 is preferred).

In addition, it contains a strong acid, a polycarboxylate, an organic compound and a water residue removing solution which can form a complex or a chelating agent with Cu, and the concentration of the strong acid is 0.1 to 5% by weight (0.3 to 3% by weight is preferred). The concentration of the carboxylate is from 0.5 to 20% by weight (0.75 to 10% by weight is preferred). The concentration of the organic compound is 0.5 to 60% by weight (2 to 40% by weight is preferred, and 3 to 30 is more preferred). The pH is 4 to 7 (pH is preferably 4 to 6). The strong acid molar ratio relative to the polycarboxylate is 0.3 to 1 (0.35 to 0.8 is preferred).

Removal of Cu oxide and/or residue after dry process

The residue removing method of the present invention is mainly a method of removing a residue existing in a semiconductor substrate after a dry process (dry etching and/or ashing) in a process of forming a capacitor structure, a double damascene structure, and the like. Specifically, the residue which is present on the semiconductor substrate having the Cu/low-k multilayer wiring structure after the dry process is removed by using the residue removal liquid described above.

The present invention also provides a method of fabricating a semiconductor device. The manufacturing method is characterized in that: (1) a step of dry etching and/or ashing a semiconductor substrate having a low dielectric film (low-k film) having copper as a wiring material as an interlayer insulating material, and (2) a step of bringing the semiconductor substrate after the above (1) treatment into contact with the residue removal liquid described above.

After the low-k film is formed on the substrate, an insulating film panel such as a SiN, SiC, or TaN film can be formed on the low-k film according to the demand, and the SiN, SiC, and TaN film can be etched together with the low-k film.

The process of removing the residue is performed by bringing the semiconductor substrate as the object to be treated into contact with the residue removing liquid. The method of contacting the residue removal liquid can be appropriately set depending on the type and temperature of the residue removal liquid. The method of contacting may be, for example, by immersing a large amount of the object to be processed (wafer) contained in the cartridge in a batch in which the solution is placed, and adding the liquid above the spin-processed object (wafer). The leaf type to be washed, the spray type in which the chemical liquid is continuously sprayed on the object to be processed (wafer), and the like.

The temperature of the residue removal liquid is, for example, 10 to 60 ° C, and preferably 15 to 40 ° C. The time of contact is not particularly limited, and may be appropriately selected, but it is preferably from 0.5 minutes to 60 minutes, and more preferably from 1 minute to 40 minutes.

When the batch type is used, the wafer can be immersed in the residue removal liquid under stirring according to the demand. The stirring speed is not particularly limited and can be appropriately selected. When the waste is not easily peeled off, for example, the object to be treated may be immersed in the residue removing liquid and then washed with ultrasonic waves.

The Cu oxide removal method of the present invention can be further washed with pure water by removing the wafer of the Cu oxide and/or the residue after the dry process. The residue removal liquid can be washed away by the washing step.

The semiconductor substrate for removing the Cu oxide and/or the residue after the dry process can be used in accordance with the residue removal liquid of the present invention, and can be followed by a conventional method such as Cu wiring (for example, as described in "Detailed Semiconductor CMP Technology", edited by Toshihiro Junji , 2001 method), processing various semiconductor devices (components).

The residue removing liquid of the present invention can suppress the etching of the cerium oxide-containing film and the low-k film without causing corrosion of Cu, and can remove the residue and the Cu oxide film after the dry process which is strongly adhered in a short time. . In particular, it is possible to reduce the damage to the low-k film, and it has an inhibitory effect on minute cracks on the surface of Cu which cannot be solved by the conventional polymer stripping solution.

Example

The invention is more clearly illustrated by the following examples. However, the invention is not limited to these embodiments.

In order to study the change of the shape of the residue and the resist pattern after the dry process, a test pattern wafer with a Cu/low-k dual damascene structure formed by the Via-First process was used. The low-k film of the Cu/low-k dual damascene structure is a SiOC film formed by plasma CVD, and the insulating film screen is a SiN film. The residue after the dry process is strong and does not easily remove. Most of the residue is present at the bottom of the via hole, and a small portion is found on the sidewall of the via hole and the surface of the low-k substrate.

The test pattern wafer was immersed in the chemical solution shown in the examples and the comparative examples at 25 ° C for 1 to 3 minutes while stirring (about 600 rpm), and then rinsed with flowing ultrapure water, dried and then dried. The residue removal treatment after the dry process is performed.

After the residue was treated, the residue removal state and the cross-sectional shape after the dry process were observed by electron microscopy (SEM) for 12 via holes. Further, in order to determine whether or not a minute crack was formed on the surface of Cu, it was observed from above the 60 via holes by an electron microscope (SEM). The profile can also be observed by SEM as needed.

In addition, in order to investigate the damage to Cu and low-k film which are not easily noticeable when the test pattern wafer is attached, the original wafer after film formation is immersed in the examples and comparative examples. After 10 minutes of the drug solution, the etching rate of the substances was calculated. For the low-k film, in order to study the change in the surface state, the contact angles before and after immersion in the drug solution were measured and compared. When the contact angle changes greatly, when the temperature rise and fall analysis (TDS) is obtained, the correlation between the increase in the adsorption amount of water can be obtained. That is, the change in contact angle reflects the change in the outermost surface of the low-k film. The contact angle was measured using a contact angle meter.

Table 2 shows the examples, and Tables 4 and 6 are comparative examples. The test results using these chemical solutions are shown in Table 3, Table 5 and Table 7. The criteria for judging the test results are shown in Table 1.

Examples 1 to 25 Examples 1 to 21 are residue removal liquids composed of a strong acid and a polycarboxylate, and Examples 22 to 25 are added with NH ₄ F and an organic compound residue in addition to a strong acid and a polycarboxylate. Removal of liquid.

It is difficult to remove the residue on the Cu surface by using only the residue removal liquid composed of a strong acid and a polycarboxylate, and the addition of an organic compound and NH ₄ F can contribute to the removal of the residue. When NH ₄ F is added when the residue of the side wall of the pattern is not easily removed, it is difficult to remove the residue on the surface of the substrate, and the addition of the organic compound can increase the effect of removing the residue.

The results of the test using the chemical solutions of Examples 1 to 25 are shown in Table 3.

The results of the evaluation using the patterned wafer shown in Table 3, the residue removal liquids of Examples 1 to 25 not only did not change the spectral pattern, but also did not cause minute cracks on the Cu surface. It has excellent residue removal performance. As a result of the evaluation using the original wafer, since the etching speed of the Cu and low-k film becomes small, the contact angle of the low-k film does not change, and it is known that there is no Cu corrosion caused by the residue removing liquid and Low-k membrane damage.

In Examples 1 and 21, the use of oxalic acid, malonic acid, and citric acid in place of trifluoroacetic acid also showed the same effect.

In Examples 3 to 13 and Examples 17 to 25, oxalic acid, malonic acid, and citric acid were used in place of trifluoroacetic acid, and the same effects were also exhibited.

In Examples 1 and 2, the use of diammonium hydrogen citrate, dihydrogen ammonium citrate, and citrate instead of oxalate showed the same effect.

In Examples 3 to 7 and Examples 14 to 25, the same effect was also exhibited by using diammonium hydrogen citrate, dihydrogen ammonium citrate, and citrate instead of oxalate.

In Examples 14 to 25, it is used as an ammonium salt of a polycarboxylate, and a methylamine salt, an ethylamine salt, a diethylamine salt, a triethylenetetramine salt, a hydrogenated tetramethylammonium salt, and a gallium are used. Substituting an alkali salt also shows the same effect.

In Example 22, monoethyl ether propylene glycol acetate was used, and ethyl hydrazine methyl methanol, ethylene glycol diacetate (ethylene diacetate), diethylene glycol, triethylene glycol dimethyl ether, and B were used. Substitution with methyl hydrazine acetate and monoethyl ether diethylene glycol showed the same effect.

In Examples 23 to 25, monoethyl ether propylene glycol acetate, propylene carbonate, ethyl lactate, and propionaldehyde were used, and ethyl hydrazine methyl methanol, ethylene glycol diacetate (ethylene diacetate), and diethyl ether were used. The same effect was obtained by substituting diol, triethylene glycol dimethyl ether, ethyl acetoacetate, and monoethyl ether diethylene glycol.

When the concentration is increased in Examples 1 to 25, the effect is increased, and the effect can be sufficiently exerted when the concentration is halved.

With respect to the chemical solutions shown in Examples 1, 6, and 7, respectively, when adding 1 ppm of 3-sulfatopropionic acid as a Cu cracking agent, the Cu surface crack evaluation of Table 3 was "B" improved to "A". The same effect was also exhibited when 1 ppm of thiolactic acid, 2-amino-2-thiazoline or 2,4,6-trithiohydrogen-s-triazine was added instead of 3-thiohydropropionic acid.

When 5 ppm of benzotriazole as Cu oxidizing agent was added to each of the chemical solutions shown in Examples 1 to 7, the oxidation of Cu was prevented as compared with the case where it was not added.

When the Cu oxidation state is determined, the original wafer of Cu immersed in the chemical solution is kept at 27 ° C and the humidity is 80% or more for 24 hours or more, and then the Cu peak from CuO is observed by XPS (photoelectron spectroscopy). And proceed.

As described above, by adding a Cu crack preventing agent and preventing the Cu oxidizing agent, it is possible to impart a crack preventing effect and an oxidation preventing effect. It can be seen that the same effect is obtained for other embodiments.

The composition of the residue removal liquid of Comparative Examples 1 to 9 Comparative Examples 1 to 9 is shown in Table 4. The pH of the residue removal liquid of Comparative Examples 1 to 9 was adjusted to about pH 2.

Comparative Examples 1 to 9 all showed insufficient prevention of Cu cracking. Among the other items in Table 5, those with the following evaluation C also showed poor performance. Therefore, the liquid solutions shown in Table 4 are not suitable as the residue removing liquid.

Specifically, as shown in Comparative Examples 1 to 3, only a strong acid was contained, which caused strong corrosion of Cu. As shown in Comparative Examples 4 to 9, even if a strong acid and an organic compound were contained, and NH ₄ F was required, the crack on the Cu surface could not be suppressed in the state where the polycarboxylate was not contained.

The composition of the residue removal liquid of Comparative Examples 10 to 17 and Comparative Examples 10 to 17 is shown in Table 6.

When only the strong acid was contained as shown in Comparative Examples 10 to 13, the Cu surface was severely cracked. When a strong acid and a polycarboxylic acid were contained as shown in Comparative Example 14, and a strong acid and a monocarboxylic acid salt (ammonium acetate) as shown in Comparative Example 15, the surface of Cu was severely cracked. When Comparative Example 16, 17 contains only a salt of a polycarboxylic acid, it causes intense corrosion of Cu.

Therefore, the chemical solutions of Comparative Examples 10 to 17 are not suitable as the residue removing liquid.

From the above results, it is understood that the chemical solution of the embodiment can control the corrosion of Cu by the interaction of a strong acid and a polycarboxylate, and in particular, can suppress cracking of the Cu surface. Therefore, it is suitable as a residue removing liquid.

Claims (15)

A residue removing liquid for removing a residue of a semiconductor substrate having a Cu/low-k multilayer wiring structure after a dry process, characterized by containing a strong acid or a polycarboxylic acid capable of forming a complex or a chelating agent with Cu Salt and water, and the concentration of the strong acid capable of forming a complex or chelate with Cu is 0.1 to 10% by weight, the concentration of the polycarboxylate is 0.1 to 20% by weight, and the pH is 4 to 7. The semiconductor substrate is A copper substrate having a low dielectric film (low-k film) as an interlayer insulating material. The residue removal liquid according to claim 1, wherein the strong acid capable of forming a complex or a chelating agent with Cu is a Bronsted acid having a pKa of 3 or less at 25 °C. The residue removal liquid of claim 1, wherein the strong acid capable of forming a complex or a chelating agent with Cu is selected from the group consisting of trifluoroacetic acid, hydrobromic acid, perchloric acid, sulfuric acid, oxalic acid, malonic acid and At least one of the groups of citric acid. The residue removal liquid according to claim 1 or 2, wherein the polycarboxylate is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, malic acid, tartaric acid, hydrogen citrate a polycarboxylic acid composed of at least one of ammonium and citric acid and a base selected from the group consisting of ammonia, hydroxylamine, primary amine, secondary amine, and tertiary amine, quaternary ammonium, and polyamine. salt. The residue removal liquid according to claim 1 or 2, wherein the concentration of the strong acid which forms a complex or a chelating agent with Cu in the residue removal liquid is 0.1 to 5% by weight. For example, the residue removal liquid of claim 1 or 2, wherein The pH is 4 to 6.5. The residue removal liquid of claim 1 or 2, which still contains an organic compound. The residue removal liquid according to the seventh aspect of the patent application, wherein the organic compound is selected from the group consisting of polycarbonyls, hydroxyketones, esters, alcohols of C3 or higher, aldehydes of C3 or higher, polyethers and anthraquinones. At least one of them. The residue removal liquid according to the seventh aspect of the patent application, wherein the concentration of the strong acid which forms a complex or a chelating agent with Cu in the residue removal liquid is 0.1 to 5% by weight, and the concentration of the organic compound is 0.5 to 60% by weight. The residue removal liquid of claim 1 or 2, which still contains a fluorine compound. A residue removal liquid according to claim 10, wherein the fluorine compound is hydrogen fluoride, or a fluoride salt of ammonia, hydroxylamine, primary amine, secondary amine or tertiary amine, quaternary ammonium or polyamine. The residue removal liquid according to claim 1 or 2 further contains a crack inhibitor for Cu and/or an oxidation inhibitor for Cu. A method for removing a residue, which is a method for removing a residue existing on a semiconductor substrate after dry etching and/or ashing, characterized by dry etching and/or ashing of a semiconductor substrate and claims 1 to 12 of the patent application Any one of the residue removing liquid contacts for removing a residue of a semiconductor substrate having a Cu/low-k multilayer wiring structure which is provided as a wiring material and having an interlayer insulating material, which is present in a dry process. A low dielectric film (low-k film) semiconductor substrate. A method for removing a residue according to claim 13 which has copper as a wiring material and a semiconductor substrate having a low dielectric film (low-k film) as an interlayer insulating material. A manufacturing method comprising a method of manufacturing a semiconductor device, comprising: (1) drying a semiconductor substrate having a low dielectric film (low-k film) as a wiring material and having a low dielectric film (low-k film) as an interlayer insulating material; a step of etching and/or ashing and (2) using the semiconductor substrate after the above (1) treatment and any one of claims 1 to 12 for removing the presence of a dry process having Cu/low- The step of contacting the residue removal liquid of the residue of the semiconductor substrate of the k multilayer wiring structure.