JP2007134690A - Manufacturing method of semiconductor device and chemical used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device, along with a chemical solution used therefor, which suppresses excessive etching of the side wall of an insulating film which is damaged by etching, and also suppresses moisture absorption from the side wall. <P>SOLUTION: The manufacturing method includes: a first process in which an insulating film 30 is provided on a base material 20 on which a mask material 40 is provided, wherein the insulating film is etched using the mask material, and a metal residue generated by the etching is removed. It also includes: a second process for hydrophobing the side wall of the insulating film formed by the etching, and a third process for removing a silicon residue generated by the etching of the insulating film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device and a chemical solution used for manufacturing the semiconductor device.

  In manufacturing a semiconductor device, if an interlayer insulating film is etched to form a VIA in an interlayer insulating film on a wiring, the side wall of the interlayer insulating film may be damaged. Since the damaged sidewall is easily etched, the sidewall of the interlayer insulating film may be etched together with the etching product when the etching product is removed with a chemical solution. When the sidewall of the interlayer insulating film is excessively etched, there arises a problem that the diameter of the VIA becomes excessively large.

In addition, the damaged sidewall of the interlayer insulating film easily absorbs moisture, which may affect the electrical characteristics of the completed semiconductor device. In particular, a low dielectric constant material (hereinafter referred to as a low-k film) such as MSQ (Methyl Silses Quioxane) employed as an interlayer insulating film is easily damaged, and the damaged portion is highly hygroscopic.
JP 2001-110899 A International Publication No. 2005 / 034194A2 Pamphlet

  Provided are a method for manufacturing a semiconductor device capable of suppressing excessive etching of a sidewall of an insulating film damaged by etching and suppressing moisture absorption from the sidewall, and a chemical used in the method.

  A method of manufacturing a semiconductor device according to an embodiment of the present invention includes: providing an insulating film on a base material; providing a mask material on the insulating film; etching the insulating film using the mask material; A first process for removing metal residues generated by etching the insulating film; a second process for hydrophobizing the sidewalls of the insulating film formed by etching; and removing silicon residues generated by etching the insulating film. And a third process.

  A method of manufacturing a semiconductor device according to an embodiment of the present invention includes: providing an insulating film on a base material; providing a mask material on the insulating film; etching the insulating film using the mask material; Removing metal residues generated by etching the insulating film, hydrophobizing the side walls of the insulating film formed by etching, and removing silicon residues generated by etching the insulating film.

  A method of manufacturing a semiconductor device according to an embodiment of the present invention includes: providing an insulating film on a base material; providing a mask material on the insulating film; etching the insulating film using the mask material; Removing a metal residue generated by etching the insulating film, hydrophobizing a side wall of the insulating film formed by etching, and removing a silicon residue generated by etching the insulating film.

  A chemical used for manufacturing a semiconductor device according to an embodiment of the present invention is a chemical used for manufacturing a semiconductor device, and includes a silylating agent for hydrophobizing the material to be etched, and the material to be etched. It contains at least a fluorine compound that dissolves a silicon residue generated by etching.

  The manufacturing method of a semiconductor device and the chemical used in the method can suppress excessive etching of the sidewall of the insulating film damaged by etching, and can suppress moisture absorption from the sidewall.

  Embodiments according to the present invention will be described below with reference to the drawings. This embodiment does not limit the present invention.

(First embodiment)
1 to 3 are sectional views showing a flow of a method for manufacturing a semiconductor device according to the first embodiment of the present invention. In the first embodiment, the wiring 20 embedded in the insulating material 10 by the damascene method is used as a base material. The wiring 20 is made of, for example, copper, tungsten, aluminum, or the like. At that time, it is preferable to form a barrier metal between the wiring 20 and the insulating material 10. The barrier metal is, for example, titanium, tantalum, titanium nitride, or tantalum nitride. In the first embodiment, the wiring 20 is almost composed of copper. Usually, a semiconductor substrate (not shown) and a semiconductor element (not shown) formed on the semiconductor substrate are formed under the insulating material 10. At least a part of the wiring 20 is formed so as to be electrically connected to an electrode or the like of the semiconductor element.

First, as shown in FIG. 1, an interlayer insulating film 30 is deposited on the insulating material 10 and the wiring 20. The interlayer insulating film 30 is a low-k film, and is a film made of a material in which an organic functional group such as a methyl (CH ₃ ) group is added to a Si—O bond, such as MSQ. The interlayer insulating film 30 may be a single layer or a laminated film deposited by combining a plurality of types of films. At least one kind of the laminated film is a film made of a material in which an organic functional group is added to a Si—O bond. When depositing a laminated film, a stopper film may be deposited under the laminated film. For example, a SiC film or a SiCN film is preferably used as the stopper film.

  Next, a mask material 40 is provided on the interlayer insulating film 30. The mask material 40 may be either a photoresist or a hard mask. Preferably, the mask material 40 is a hard mask made of a silicon nitride film or the like. The hard mask may be used by stacking a plurality of materials.

  Next, as shown in FIG. 2, the mask material 40 is patterned by using a lithography technique and RIE (Reactive Ion Etching).

Next, as shown in FIG. 3, the interlayer insulating film 30 is etched using the mask material 40 as a mask to form a VIA hole 50 reaching the wiring 20. The etching product 60 is generated by etching the interlayer insulating film 30. The etching product 60 is a reaction product of the material of the wiring 20 (copper) and an etching gas, for example, copper oxide such as CuO, Cu ₂ O, CuF ₂ , CuCO ₃ , copper fluoride, copper These include carbonates (hereinafter also referred to as metal residues) and silicon compounds such as SiO 2 _X (hereinafter also referred to as silicon residues). Further, in this etching process, the sidewall of the interlayer insulating film 30 is damaged, thereby forming the damaged layer 32. As described above, the damage layer 32 is easily etched and is in a highly hygroscopic state.

  Next, in order to remove the etching product 60, a chemical treatment is performed as a first treatment using a chemical containing at least one of an inorganic acid, an organic acid, a salt of an inorganic acid, or a salt of an organic acid. Thereby, the etching product 60 can be removed while suppressing the etching of the damaged layer 32. Examples of inorganic acids include hydrochloric acid (HCl), dilute sulfuric acid, dilute sulfurous acid, hydrocyanic acid, carbonic acid, nitrous acid, phosphoric acid, hydrobromic acid (HBr), hydroiodic acid (HI), hydrosulfuric acid, and the like. is there. Examples of organic acids include citric acid, oxalic acid, acetic acid, maleic acid, fumaric acid, formic acid, benzoic acid, phthalic acid, terephthalic acid, salicylic acid, lactic acid, malic acid, tartaric acid, carboxylic acids such as propionic acid, benzene There are sulfonic acids such as sulfonic acid and toluenesulfonic acid, and amino acids such as glycine, alanine, serine, cysteine, lysine, phenylalanine, tyrosine, and glutamic acid. Examples of inorganic acid salts or organic acid salts include ammonium salts and organic amine salts. At this time, since the possibility of etching the base material (copper) increases when the oxidation-reduction potential of the chemical solution is higher than 0.5 V, the oxidation-reduction potential is preferably 0.5 V or less.

  After the first treatment, rinsing is performed with pure water. At this time, rinsing may be performed with an alcohol such as IPA (Isopropyl Alcohol), methanol, ethanol, or propanol. Thereafter, rinsing with pure water may be performed. After rinsing with alcohol, the semiconductor substrate may be once dried.

  Next, in order to make the damaged layer 32 hydrophobic, as a second treatment, the semiconductor substrate is exposed to a chemical solution containing a silylating agent. Thereby, the damage layer 32 is hydrophobized.

  In order to promote the reaction in both the first treatment and the second treatment, the treatment may be performed with a chemical solution at an elevated temperature.

4 to 6 are views showing a state in which the damage layer 32 is formed in the interlayer insulating film 30 made of MSQ, and the damage layer 32 is hydrophobized. FIG. 4 is a diagram showing the structure of the terminal portion of the MSQ film. The MSQ film is a film in which functional groups such as O and CH ₃ are bonded to silicon atoms. When the interlayer insulating film 30 is processed by RIE or the like, its side walls are hydrolyzed. That is, as shown in FIG. 5, the hydrophobic CH ₃ group is detached from the MSQ film, and the hydrophilic OH group (silanol group: —Si—OH) is bonded. Thereby, the damage layer 32 is formed. As indicated by a wavy circle C1 in FIG. 5, a hydrophilic OH group is bonded to the end of the damage layer 32. When OH groups come into contact with water present in the atmosphere, OH groups hydrogen bond with water. Thereby, the damage layer 32 absorbs moisture.

On the other hand, after execution of the second treatment, the damage layer 32 is silylated (—Si—O—Si—R) and hydrophobized. Silylation is a process in which a silylating agent reacts with an OH group of silanol to replace the OH group with a hydrophobic group. In this embodiment, a methyl group (CH ₃ group) is used as the hydrophobic group. Thereby, as shown by a broken-line circle C2 in FIG. 6, the side wall of the interlayer insulating film 30 is terminated with a CH ₃ group. As a result, the damage layer 32 is eliminated and the side wall of the interlayer insulating film 30 becomes hydrophobic.

  This hydrophobic group is not limited to a methyl group, and can be replaced with various functional groups depending on the type of silylating agent. Examples of silylating agents include chlorosilanes (including dichlorosilanes and trichlorosilanes), alkoxysilanes, cyclosiloxanes, polysiloxanes, silylamines, silylamides, HMDS (hexamethyldisilazane), and trimethylchlorosilane. Or there is octylchlorosilane.

Note that a silylating agent containing a halogen (Cl, F, Br, I, etc.), a sulfone group (SO ₃ H), a nitro group (NOx) or the like as a functional group may erode the metal wiring 20. . Therefore, when a metal is used for the wiring 20, it is preferable to use a silylating agent that does not contain a halogen, a sulfone group, or a nitro group.

  It is preferable to heat-treat the semiconductor substrate after the second treatment. This is because the silylation of the damage layer 32 is further promoted. At this time, it is preferable that the heat treatment is performed in an atmosphere in which almost no oxidizing substance is removed in order to suppress oxidation of the base material.

Further, in order to remove silicon residues such as SiOx, as a third treatment, the semiconductor substrate is exposed to a chemical solution in which a fluorine compound such as HF, NH ₄ F, a fluorine compound of an organic amine, or a fluorine compound of an organic amide is mixed. When the base material is a material containing silicon (for example, a silicon nitride film, a silicon carbonitride film, etc.), a silicon residue is generated. Silicon residue is one of the etching products. At this time, since the side wall of the interlayer insulating film 30 has already been silylated by the second treatment, the etching of the side wall of the interlayer insulating film 30 is suppressed. Therefore, the silicon residue can be effectively removed by the third treatment. This third treatment may be performed after or before the treatment with at least one of an inorganic acid, an organic acid, an inorganic acid salt, or an organic acid salt in the first treatment.

Although the etching of the sidewall of the interlayer insulating film 30 is suppressed by silylation, the amount of water and the amount of fluorine compound such as hydrofluoric acid is used for the chemical solution used for the third treatment so as not to etch the damaged layer 32. It is preferable to control the pH by controlling the pH. More specifically, it is preferable to change the pH from a weakly acidic to 4 or higher alkaline solution by controlling dissociation into F ⁻ ions and generation of HF ₂ ⁻ ions. By using such a chemical solution, it is possible to control the etching of SiO ₂ so as not to etch the damaged layer 32 excessively in the third treatment.

  The first process and the second process according to the first embodiment were performed by exposing the semiconductor substrate to a chemical solution. However, the first process and the second process can also be performed by performing a heat treatment in an atmosphere of a gas containing a desired drug. For example, the second treatment may be a heat treatment performed in steam containing a silylating agent.

  In the first embodiment, the second process may be executed after the first process, or the first process may be executed after the second process. When the second process is performed after the first process, the damage layer 32 is hydrophobized after removing the etching product, so that the entire damage layer 32 is surely hydrophobic without being disturbed by the etching product. Can be When the first process is executed after the second process, the damage layer 32 is hydrophobized and then the etching product is removed, so that the damage layer 32 is further prevented from being etched in the first process. Can do.

  In the first embodiment, the first process and the second process may be performed discontinuously. However, the first process and the second process are preferably executed sequentially (sequentially) in the same apparatus. More preferably, the first process and the second process are continuously performed in an atmosphere in which almost no oxidizing substances and moisture are excluded in the same apparatus. When the first process and the second process are performed discontinuously, even if the etching product 60 is removed by the first process, the damaged layer 32 may absorb moisture during standby. The moisture that has absorbed moisture may affect the electrical characteristics of the semiconductor device after completion of the semiconductor device. Therefore, moisture absorption to the interlayer insulating film 30 is not preferable.

  When the first process and the second process are continuously performed in the same apparatus, the damage layer 32 has little opportunity to come into contact with moisture in the atmosphere, so that it hardly absorbs moisture and thus is silylated (hydrophobized). ) Therefore, the electrical characteristics are not affected after the completion of the semiconductor device.

  The third process may be performed discontinuously after the first and second processes. At this time, since the side wall of the interlayer insulating film 30 is silylated, moisture absorption on the side wall can be suppressed. However, of course, the third process may be executed continuously after the first and second processes. Thereby, the manufacturing process by this embodiment is shortened.

  In the first embodiment, the first process and the second process are executed using different chemical solutions. However, the semiconductor substrate may be exposed to a mixed chemical solution obtained by mixing the chemical solution used for the first treatment and the chemical solution used for the second treatment. In this case, the etching product 60 can be removed and the side wall of the interlayer insulating film 30 can be made hydrophobic by executing the chemical treatment once. Thereafter, it is preferable to further heat-treat the semiconductor substrate. At this time, the heat treatment is preferably performed in an atmosphere from which almost all oxidizing substances are excluded.

(Second Embodiment)
In the second embodiment, the etching product 60 is removed and the side wall of the interlayer insulating film 30 is hydrophobized by a single chemical treatment. Since the manufacturing method of the semiconductor device according to the second embodiment is the same as the manufacturing method shown in FIGS. 1 to 3, the illustration of the second embodiment is omitted.

In 2nd Embodiment, the chemical | medical solution containing a silylating agent is used as a chemical | medical solution which hydrophobizes. At this time, it is preferable to use a mixed solution (hereinafter referred to as a first mixed solution) of a silylating agent, water, and a basic compound (ammonia, organic amines, organic amide, etc.). Ammonia easily forms a water-soluble complex with copper and dissolves copper. Therefore, when the wiring 20 is copper, copper complexes make difficult organic amines _{([R 1 R 2 R 3} R 4 N] + OH-: R1~4 functional groups) basified and organic amides It is preferable to use it as a compound. Examples of such a compound include TMAH (tetramethylammonium hydroxide), TEAH (tetraethylammonium hydroxide), TEMAH (triethylmonomethylammonium hydroxide), and choline (Choline).

  In addition, since the possibility of etching the base material (copper) increases when the oxidation-reduction potential of the first mixed solution is higher than 0.5 V, the oxidation-reduction potential is preferably 0.5 V or less.

  In order to remove etching products, at least one of carboxylic acids, amino acids, or salts thereof is further mixed with the first mixed solution. Hereinafter, this mixed solution is referred to as a second mixed solution. Examples of carboxylic acids include citric acid, oxalic acid, acetic acid, maleic acid, fumaric acid, formic acid, benzoic acid, phthalic acid, terephthalic acid, salicylic acid, lactic acid, malic acid, tartaric acid, propionic acid, and the like. Examples of amino acids include glycine, alanine, serine, cysteine, lysine, phenylalanine, tyrosine, and glutamic acid. By exposing the semiconductor substrate to the second liquid mixture, etching products can be removed and the side walls of the interlayer insulating film 30 can be hydrophobized by a single chemical treatment.

  In addition, some carboxylic acids, amino acids, or salts thereof form a complex such as a chelate with copper. Therefore, it is desirable to select organic amines, carboxylic acids, amino acids and the like so as to selectively etch a copper compound such as CuOx with respect to copper. In particular, it is preferable to select a carboxylic acid having only one carboxyl group that does not form a chelate, one that does not form a complex with Cu due to steric hindrance or the like, or that does not easily form a complex with Cu. However, when it is difficult to dissolve CuOx as in the case where the pH of the chemical solution is higher than 4, it is preferable to select one that forms a complex such as a chelate.

  In order to remove a silicon residue made of a silicon compound, HF, NH 4 F, a fluorine compound of organic amine, or a fluorine compound of organic amide may be mixed with the second mixed solution. This mixed solution is referred to as a third mixed solution. By exposing the semiconductor substrate to the third liquid mixture, etching products (copper compound and silicon compound) can be removed and the side walls of the interlayer insulating film 30 can be hydrophobized by a single chemical treatment.

The pH of the third mixed solution is preferably controlled by controlling the amount of water and the amount of a fluorine compound such as hydrofluoric acid so that the damaged layer 32 is not etched. More specifically, it is preferable to change the pH from a weakly acidic to 4 or higher alkaline solution by controlling dissociation into F ⁻ ions and generation of HF ₂ ⁻ ions. By using such a chemical solution, it is possible to control the etching of SiO ₂ so as not to etch the damaged layer 32 excessively in the third treatment.

  When the etching solution used in the first treatment does not contain hydrofluoric acid, the metal residue may be removed, but the silicon residue may remain without being removed. At this time, if the second treatment is performed after the first treatment, the silicon residue is hydrophobized, which makes it difficult to remove the silicon residue. Further, there is a problem that silicon residue is further generated by the second treatment. By exposing the semiconductor substrate to the third mixed solution, removal of metal residues, removal of silicon residues, and hydrophobization treatment can be performed by a single chemical treatment, thus avoiding such problems. Can do.

  It is preferable to heat-treat the semiconductor substrate after this one chemical treatment. This is because the silylation of the damage layer 32 is further promoted. In order to suppress the oxidation of the base material (copper), it is preferable to perform the heat treatment in an environment in which almost no oxidizing atmosphere is excluded.

  The second embodiment has the same effect as the first embodiment.

(Third embodiment)
In the third embodiment, after the first process is performed, the removal of silicon residues and the hydrophobicization of the sidewalls of the interlayer insulating film 30 are performed simultaneously in the same process step. Since the manufacturing method of the semiconductor device according to the third embodiment is the same as the manufacturing method shown in FIGS. 1 to 3, the illustration of the third embodiment is omitted. Moreover, since the first process is the same as that in the first embodiment, the description thereof is omitted. In addition, since the possibility that the base material (copper) is etched increases when the oxidation-reduction potential of the chemical used for the first treatment is higher than 0.5 V, the oxidation-reduction potential is preferably 0.5 V or less. .

In the third embodiment, as a chemical solution for removing and hydrophobizing silicon residues, a chemical solution in which a silylating agent is mixed with a fluorine compound such as HF, NH ₄ F, a fluorine compound of an organic amine, a fluorine compound of an organic amide ( Hereinafter, the semiconductor substrate is exposed to a fourth mixed solution).

  By exposing the semiconductor substrate to the fourth liquid mixture, the silicon residue can be removed and the side walls of the interlayer insulating film 30 can be hydrophobized by a single chemical treatment.

  Further, since the removal of the silicon residue and the hydrophobization are performed at the same time, the above problem that the silicon residue remains due to etching or the second treatment does not occur.

Although the etching of the sidewall of the interlayer insulating film 30 is suppressed by silylation, the amount of water and the amount of fluorine compound such as hydrofluoric acid are controlled for the fourth mixed solution so as not to etch the damaged layer 32. It is preferable to control the pH. More specifically, it is preferable to change the pH from a weakly acidic to 4 or higher alkaline solution by controlling dissociation into F ⁻ ions and generation of HF ₂ ⁻ ions. By using such a chemical solution, it is possible to control the etching of SiO ₂ so that the damaged layer 32 is not excessively etched in the removal of the silicon residue and the hydrophobic treatment.

  It is preferable to heat-treat the semiconductor substrate after removing the silicon residue and making it hydrophobic. This is because the silylation of the damage layer 32 is further promoted. In order to suppress the oxidation of the base material (copper), it is preferable to perform the heat treatment in an environment in which almost no oxidizing atmosphere is excluded. The third embodiment further has the same effect as that of the first embodiment.

In the first to third embodiments, the wiring 20 mainly made of copper is used. However, instead of copper, a metal or metal compound such as tungsten, titanium, or aluminum may be used as the wiring. In this case, H ₂ O ₂ , O ₃ , peroxosulfuric acid, nitric acid, nitrate, sulfuric acid, sulfate, chlorous acid, chlorite, hypochlorous acid are used to form a passive state on the metal surface such as titanium or aluminum. An oxidizing agent such as chloric acid or hypochlorite may be added to the chemical solution.

  FIG. 7 is an example of a graph showing the relationship between the molar ratio of hydrofluoric acid to the organic amine in the chemical solution used in the first to third embodiments and the pH of the chemical solution. When the molar ratio of hydrofluoric acid is 1 or more, the etching rate of the silicon oxide film becomes high, so that not only the silicon residue but also the damaged layer 32 is etched. Accordingly, the molar ratio of hydrofluoric acid is preferably less than 1. When the molar ratio of hydrofluoric acid is less than 1, the pH of the chemical solution changes from weakly acidic 4 or higher to alkaline. That is, the chemical solution for removing the etching compound in the first to third embodiments is preferably pH 4 or higher.

Sectional drawing which shows the manufacturing method of the semiconductor device according to 1st Embodiment concerning this invention. Sectional drawing which shows the manufacturing method of the semiconductor device following FIG. Sectional drawing which shows the manufacturing method of the semiconductor device following FIG. The figure which shows the basic structure of a MSQ film | membrane. FIG. 6 is a structural diagram of the interlayer insulating film 30 when a damaged layer 32 is formed. FIG. 6 is a structural diagram of the interlayer insulating film 30 when the damaged layer 32 is hydrophobized. The graph which shows the relationship between the molar ratio of the hydrofluoric acid and organic amine in the chemical | medical solution used in the 1st-3rd embodiment, and the pH of the chemical | medical solution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Insulating material 20 ... Base material 30 ... Insulating material 40 ... Mask material 50 ... VIA
60 ... Etching product

Claims (5)

An insulating film is provided on the base material,
A mask material is provided on the insulating film,
Etching the insulating film using the mask material,
A first treatment for removing a metal residue generated by etching the insulating film;
A second treatment for hydrophobizing the side wall of the insulating film formed by etching;
A third treatment for removing silicon residues generated by etching the insulating film;
A method for manufacturing a semiconductor device comprising: An insulating film is provided on the base material,
A mask material is provided on the insulating film,
Etching the insulating film using the mask material,
Removing metal residues generated by etching the insulating film;
A method of manufacturing a semiconductor device, comprising hydrophobizing a sidewall of the insulating film formed by etching and removing a silicon residue generated by etching the insulating film. An insulating film is provided on the base material,
A mask material is provided on the insulating film,
Etching the insulating film using the mask material,
A semiconductor comprising: removing metal residues generated by etching the insulating film; hydrophobizing sidewalls of the insulating film formed by etching; and removing silicon residues generated by etching the insulating film Device manufacturing method. A chemical used for manufacturing a semiconductor device,
A chemical solution containing at least a silylating agent for hydrophobizing a material to be etched and a fluorine compound that dissolves a silicon residue generated by etching the material to be etched.   5. The method according to claim 4, further comprising at least one of an inorganic acid, an organic acid, a salt of an inorganic acid, or a salt of an organic acid for dissolving a metal residue generated by etching the material to be etched. Chemical solution.

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