JP2009289774A - Residual removing liquid after semiconductor dry process, and residual removing method using the same - Google Patents

Abstract

The present invention provides a residue removing solution capable of effectively removing residues after a dry process in a manufacturing process of a semiconductor device having NiSi (nickel silicide).
A solution for removing a residue present after dry etching and / or ashing a semiconductor substrate containing nickel silicide (NiSi) is selected from the group consisting of ammonium fluoride, amine fluoride, and tetraalkylammonium fluoride. At least one fluoride salt selected from the group consisting of ammonium salts other than fluoride salts, amine salts other than fluoride salts, and tetraalkylammonium salts other than fluoride salts. And containing water, the concentration of the fluoride salt is 5% by weight or more, the concentration of the salt other than the fluoride salt is 3% by weight or more, and the total concentration of the tetraalkylammonium fluoride and the tetraalkylammonium salt other than the fluoride salt is Residue removing liquid having a pH of less than 15 and less than 15% by weight.
[Selection figure] None

Description

  The present invention relates to a chemical solution (residue removing solution) for removing residues formed during dry etching and / or ashing (ashing) in a semiconductor device manufacturing process, and a semiconductor that removes these residues using the chemical solution. The present invention relates to a device manufacturing method. In particular, the present invention relates to a residue removing solution after a dry process used for manufacturing a semiconductor device having Ni / Si (nickel silicide) in a source / drain (S / D) or gate portion as a current terminal electrode material.

  As miniaturization of semiconductor devices progresses, the resistance of the gate, source and drain increases, and for the high-speed operation of MOS transistors, the surface of silicon constituting the gate, source and drain reacts with metal (silicidation). Therefore, it is necessary to increase the transistor current by reducing resistance components parasitic on the transistor such as electrodes and diffusion layer resistance.

The resistivity of NiSi is slightly lower than that of CoSi ₂ and TiSi ₂ used in the conventional production line. Therefore, when NiSi is used, it can be operated at higher speed than conventional cobalt silicide or the like. After the 65 nm process, a NiSi (nickel silicide) layer having a lower resistance is formed on the thin line portions such as the source / drain (S / D) and the gate contact portion.

  Recently, it has also been studied as a gate electrode, and a method of making the entire gate electrode silicide is proposed. This is because since only the materials used in the existing semiconductor process technology are used, the introduction is easy, and at the same time, the performance is expected to be improved as compared with the current gate electrode using polysilicon.

  Regarding the metalization of the gate electrode, there are a method of metalizing only the contact portion and a method of metalizing all of the gate insulating film. The FUSI (FUlly SIlicide) technology is a technology in which everything is metallized (nickel silicide) with nickel. FUSI becomes the mainstream after the 32 nm generation, and since the gate electrode is completely alloyed and formed of a metal compound (silicide) of silicon and nickel, its electrical properties are closer to that of a conductor than a polysilicon gate electrode. Therefore, it is said that a high-performance transistor exhibiting ideal characteristics can be obtained by optimally adjusting the work function of each of the nMOS and pMOS.

  When such a gate using NiSi is formed, a resist is applied to the formed film such as NiSi, lithography is performed, and then dry etching is performed. Further, in order to form a plug for connecting the gate or source / drain made of NiSi and the upper wiring, a contact hole is required. In order to form this contact hole, a resist is applied to the formed insulating film, lithography is performed, and then dry etching is performed.

  After gates and contact holes are formed by these dry etchings, unnecessary resist and the like are removed from the substrate by ashing or the like. However, unnecessary materials that cannot be completely removed (hereinafter referred to as “residues after the dry process”) remain on the substrate even after this process.

  If there is a residue after the dry process in the contact hole or gate for forming the gate, source / drain and plug formed by dry etching, it may cause a defect in the semiconductor device. Therefore, these residues are removed using a residue removing solution such as a polymer stripping solution.

  Conventionally, dilute hydrofluoric acid or APM (ammonia / hydrogen peroxide solution mixed solution) has been used to remove residues after these dry processes. However, when dilute hydrofluoric acid is used, NiSi is easily corroded. In addition, the multi-layered insulating film forming the contact hole is side-etched, so that it is impossible to perform processing as designed. Further, a step is likely to occur due to a difference in etching rate depending on the film, which hinders formation of a plug. In addition, APM has a weak residue removal effect, and in particular, after dry etching, the residue changes in quality and forms a substance that is difficult to remove with APM, which makes it impossible to remove the residue. For this reason, the allowable time from the dry etching to the cleaning process for removing the residue is small, and there is no allowance for the manufacturing process, which greatly affects the yield. Thus, an effective post-dry process residue removal liquid used in the manufacture of semiconductor devices having NiSi has not yet been developed.

In order to solve these problems, Patent Document 1 describes a cleaning solution used for cleaning a substrate containing a fluorine compound, a chelating agent, and an organic acid salt and having a nickel silicide layer formed thereon. . However, since the cleaning liquid of Patent Document 1 shows acidity, the nickel silicide layer is easily corroded, and the multilayer insulating film forming the contact hole is side-etched by HF generated in the liquid, There is a problem that a step due to the difference in etching amount occurs, and processing according to the design dimension cannot be performed.
JP 2005-317636 A

  An object of the present invention is to provide a residue removing liquid capable of effectively removing residues after a dry process in a manufacturing process of a semiconductor device having NiSi (nickel silicide).

  As a result of intensive studies to achieve the above object, the present inventors have at least selected from the group consisting of ammonium fluoride (A1), amine fluoride (A2), and tetraalkylammonium fluoride (A3). Selected from the group consisting of one fluoride salt (A), an ammonium salt (B1) other than a fluoride salt, an amine salt (B2) other than a fluoride salt, and a tetraalkylammonium salt (B3) other than a fluoride salt A chemical solution (residue removal solution) containing at least one salt other than fluoride salt (B) and water (C) effectively removes residues generated after the dry process of a semiconductor device having NiSi (nickel silicide). I found what I could do. Further, it was also confirmed that the residue removing solution has a low etching rate of the insulating film of the semiconductor device and hardly generates side etching. The present inventor has further studied and completed the present invention.

  That is, the present invention provides a removal solution for residues present after dry etching and / or ashing of a semiconductor substrate containing nickel silicide (NiSi), and a method for manufacturing a semiconductor device using the residue removal solution.

Item 1. A solution for removing residues present after dry etching and / or ashing a semiconductor substrate containing nickel silicide (NiSi),
(A) at least one fluoride salt selected from the group consisting of ammonium fluoride (A1), amine fluoride (A2), and tetraalkylammonium fluoride (A3);
(B) At least one fluoride salt selected from the group consisting of ammonium salts other than fluoride salts (B1), amine salts other than fluoride salts (B2), and tetraalkylammonium salts other than fluoride salts (B3) Including salt other than (C) water,
Concentration of fluoride salt (A) is 5% by weight or more, concentration of salt (B) other than fluoride salt is 3% by weight or more, tetraalkylammonium fluoride (A3) and tetraalkylammonium salt other than fluoride salt ( Residue removing liquid having a total concentration of B3) of less than 15% by weight and a pH of 7-9.

  Item 2. Item 2. The residue removing solution according to Item 1, wherein the fluorinated amine (A2) is at least one selected from the group consisting of fluorinated methylamine, fluorinated ethylamine, and fluorinated butylamine.

  Item 3. Item 3. The residue removing solution according to Item 1 or 2, wherein the tetraalkylammonium fluoride (A3) is at least one selected from the group consisting of tetramethylammonium fluoride, tetraethylammonium fluoride, and tetrabutylammonium fluoride.

  Item 4. Item 4. The residue removing solution according to any one of Items 1 to 3, wherein the salt (B) other than the fluoride salt is a salt of a weak acid having a pKa of 4 or more.

  Item 5. Item 5. The residue removing solution according to Item 4, wherein the salt of the weak acid is at least one selected from the group consisting of an ammonium salt of a monocarboxylic acid, an amine salt of a monocarboxylic acid, and a tetraalkylammonium salt of a monocarboxylic acid.

  Item 6. Item 6. The residue removing solution according to Item 4 or 5, wherein the salt of the weak acid is at least one selected from the group consisting of ammonium acetate, methyl acetate, ethylamine acetate, and tetramethylammonium acetate.

  Item 7. Item 4. The residue removing solution according to any one of Items 1 to 3, wherein the tetraalkylammonium salt (B3) other than the fluoride salt is at least one selected from the group consisting of tetraalkylammonium chloride and tetraalkylammonium acetate.

  Item 8. Item 8. The residue removing solution according to Items 1 to 7, wherein the salt (B) other than the fluoride salt is a salt composed of the same base as the fluoride salt (A).

  Item 9. The residue removal according to any one of Items 1 to 8, wherein the fluoride salt (A) is ammonium fluoride (A1), and the salt (B) other than the fluoride salt is an ammonium salt (B1) other than the fluoride salt. liquid.

  Item 10. The residue removal according to any one of Items 1 to 8, wherein the fluoride salt (A) is a fluorinated amine (A2), and the salt (B) other than the fluoride salt is an amine salt (B2) other than the fluoride salt. liquid.

  Item 11. Item 11. The residue removing liquid according to any one of Items 1 to 10, further comprising a surfactant.

  Item 12. Furthermore, the residue removal liquid in any one of claim | item 1 -11 containing an organic solvent.

Item 13. A method of removing residues present after dry etching and / or ashing a semiconductor substrate containing nickel silicide (NiSi),
13. A residue removing method comprising contacting the semiconductor substrate after the dry etching and / or ashing with the residue removing solution according to any one of Items 1 to 12.

  Item 14. The semiconductor substrate has a current terminal electrode containing nickel silicide (NiSi), and at least one interlayer insulating film selected from the group consisting of a silicon oxide film, a silicon nitride film, and a low dielectric constant film (Low-k film) Item 14. The method for removing a residue according to Item 13, comprising:

Item 15. (1) It has a current terminal electrode containing nickel silicide (NiSi) and has at least one interlayer insulating film selected from the group consisting of a silicon oxide film, a silicon nitride film, and a low dielectric constant film (Low-k film). A step of dry etching and / or ashing the semiconductor substrate, and (2) a step of bringing the semiconductor substrate treated in the above (1) into contact with the residue removing liquid according to any one of Items 1 to 12, A method for manufacturing a semiconductor device.

  By using the residue removing liquid of the present invention, residues after a dry process in the manufacture of a semiconductor substrate having NiSi (nickel silicide) can be removed over a long period of time. In particular, the residue is easily transformed into a substance that is difficult to remove over time, but the residue removing solution of the present invention can remove such a substance. For this reason, it becomes possible to extend the process margin, which has been several hours in the prior art, to one day or more, thereby stabilizing the manufacturing of the semiconductor process and reducing the manufacturing cost.

  Moreover, since NiSi is not corroded, a plug can be formed on a smooth NiSi surface. For this reason, it is possible to connect a strong plug with good adhesion, and the resistance is small due to contact.

  Furthermore, the residue removing solution of the present invention hardly suppresses etching of the insulating film, and therefore can suppress side etching of contact holes. In particular, even when the insulating film is weak in structure, side etching is difficult to cause, and steps of each layer are difficult to be formed. Therefore, plugs with no dimensional change can be formed, and defects in semiconductor devices can be reduced.

  Hereinafter, the present invention will be described in detail.

I. Residue Removal Solution After Semiconductor Dry Process The residue removal solution of the present invention is a removal solution for residues (residues after the dry process) that exist after dry etching and / or ashing of a semiconductor substrate containing nickel silicide (NiSi).

  The residue removal solution is at least one fluoride salt (A) selected from the group consisting of ammonium fluoride (A1), fluoride amine (A2), and tetraalkylammonium fluoride (A3). An ammonium salt (B1), an amine salt (B2) other than a fluoride salt, a salt (B) other than at least one fluoride salt selected from the group consisting of a tetraalkylammonium salt (B3) other than a fluoride salt, and It contains water (C).

  The residue after the dry process when the structure having NiSi (nickel silicide) is formed includes silicon (Si), nickel (Ni), and oxides and fluorides thereof.

<Fluoride salt (A)>
At least one fluoride salt (A) selected from the group consisting of ammonium fluoride (A1), fluoride amine (A2), and tetraalkylammonium fluoride (A3) is mainly composed of a silicon-containing component contained in the residue. Nickel-containing components can be removed.

  There is no restriction | limiting in particular as a fluorinated amine (A2), For example, branching, such as linear amines, such as fluorinated methylamine, fluorinated ethylamine, and fluorinated butylamine, fluorinated dimethylamine, fluorinated diethylamine, and fluorinated triethylamine An amine etc. are mentioned. Of these, linear fluorinated methylamine, fluorinated ethylamine, and fluorinated butylamine are most preferred.

The tetraalkylammonium fluoride (A3), is not particularly limited, for example, include fluoride tetra C _1-6 alkyl ammonium, etc., more specifically, for example, tetramethylammonium fluoride, tetraethylammonium fluoride And tetrabutylammonium fluoride. Of these, tetramethylammonium fluoride is most preferred.

  Commercially available crystals may be used as at least one fluoride salt (A) selected from the group consisting of ammonium fluoride (A1), amine fluoride (A2) and tetraalkylammonium fluoride (A3). Alternatively, an aqueous solution formed by mixing an acid and a base forming these salts in water, a crystal obtained by drying the acid, a hydrate crystal thereof, or the like may be used.

Side etching of the insulating film is performed by reacting a small amount of HF present in the residue removal solution having a pH of 7 to 9 containing these fluoride salts with F ⁻ to realize a composition containing more HF ²⁻ than HF. It can suppress and can improve residue removability.

The blending amount (concentration) of at least one fluoride salt (A) selected from the group consisting of ammonium fluoride (A1), fluoride amine (A2), and tetraalkylammonium fluoride (A3) is higher than HF. ^In terms of realizing a composition with a large amount of ^{2-, it} is generally 5% by weight or more in the residue removing solution. The amount is preferably 10 to 60% by weight, more preferably 15 to 40% by weight, and particularly preferably 15 to 25% by weight.

  The higher the compounding amount (concentration) of these fluoride salts (A), the higher the residue removal capability, and the less likely the etching of the insulating film occurs. In addition, the life of the residue removal solution is extended. On the other hand, if the concentration is too high, the viscosity of the residue removal solution increases and crystallization is likely to occur, so the upper limit is preferably set in the above range. If the content is less than 5% by weight, the residue removal property is poor, the insulating film is easily etched, and a step is formed in the laminated portion of the insulating film.

<Salts other than fluoride salts (B)>
At least selected from the group consisting of an ammonium salt (B1) other than a fluoride salt, an amine salt (B2) other than a fluoride salt, and a tetraalkylammonium salt (B3) other than a fluoride salt simultaneously with the fluoride salt (A) Inclusion of salt (B) other than one kind of fluoride salt increases the salt concentration, reduces the amount of water involved in the dissociation of fluoride salt (A), and controls dissociation, improving residue removability and insulating film The effect of suppressing side etching is obtained.

Salts other than at least one fluoride salt selected from the group consisting of ammonium salts (B1) other than fluoride salts, amine salts (B2) other than fluoride salts, and tetraalkylammonium salts (B3) other than fluoride salts Examples of (B) include halogen salts such as chloride salts and bromide salts; formate salts (formic acid: pKa3.55), acetate salts (acetic acid: pKa4.56), propionate salts (propionic acid: pKa4.67), etc. Monocarboxylate; oxalate (oxalic acid: pKa 3.82), polycarboxylates such as malonate (malonic acid: pKa 5.28), citrate (citric acid: pKa 5.69); carbonate (carbonic acid: pKa 6.35); phosphate (phosphoric acid) : PKa 7.2) and the like.

Among these salts, anions form complexes with Ni, so ammonium, amine, tetra C _1-6 alkyl ammonium chloride salts, acetates, oxalates, malonates, citrates, etc. preferable.

  Specifically, chloride salts such as ammonium chloride, amine chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride; ammonium acetate, methylamine acetate, ethylamine acetate, tetramethylammonium acetate, tetraethylammonium acetate, acetic acid Acetates such as tetrabutylammonium; oxalates such as ammonium oxalate, tetramethylammonium oxalate, tetraethylammonium oxalate, tetrabutylammonium oxalate; ammonium malonate, methylamine malonate, ethylamine malonate, tetramalonate malonate Malonates such as methylammonium, tetraethylammonium malonate, tetrabutylammonium malonate; ammonium citrate, methylamine citrate, que Acid ethylamine, tetramethylammonium citrate, citric acid tetraethylammonium, citrate salts such as citric acid tetrabutylammonium is preferably used.

  More preferably, it is a salt of a weak acid having a pKa of 4 or more, and particularly preferably ammonium acetate, methylamine acetate, ethylamine, tetramethylammonium acetate, ammonium malonate, methylamine malonate, ethylamine malonate, tetramalonate malonate. Methyl ammonium, tetraethyl ammonium malonate, and tetrabutyl ammonium malonate. Of these, ammonium salts of monocarboxylic acids, amine salts, and tetraalkylammonium salts such as ammonium acetate, methylamine, ethylamine acetate, and tetramethylammonium acetate are more preferable, methylamine acetate, ethylamine acetate, and tetramethylammonium acetate. Is most preferred.

When a tetraalkylammonium salt (B3) that does not generate protons (H ⁺ ), such as tetraalkylammonium chloride or tetraalkylammonium acetate, is added as a tetraalkylammonium salt (B3) other than a fluoride salt, a silicon oxide film The nickel-containing component can be removed without increasing the etching of the insulating film.

  Other than at least one fluoride salt selected from the group consisting of ammonium salts (B1) other than these fluoride salts, amine salts (B2) other than fluoride salts, and tetraalkylammonium salts (B3) other than fluoride salts As the salt (B), commercially available crystals may be used, an aqueous solution formed by mixing an acid and a base forming these salts in water, or a crystal obtained by drying the solution, or a hydrate thereof. Crystals or the like may be used.

Salts other than at least one fluoride salt selected from the group consisting of ammonium salts (B1) other than fluoride salts, amine salts (B2) other than fluoride salts, and tetraalkylammonium salts (B3) other than fluoride salts The blending amount (concentration) of (B) is generally 3% by weight or more in the residue removing solution from the viewpoint of improving the nickel-containing residue removing property and improving the efficiency of HF ²⁻ generation. The amount is preferably 4 to 50% by weight, more preferably 5 to 35% by weight, and particularly preferably 10 to 25% by weight.

  The total blending amount (total concentration) of tetraalkylammonium fluoride (A3) and tetraalkylammonium (B3) other than the fluoride salt is less than 15% by weight in the residue removal solution from the viewpoint of reducing the viscosity. . Preferably it is 3 to 14.9% by weight, more preferably 5 to 14.9% by weight, and particularly preferably 8 to 14.9% by weight.

<Combination of fluoride salt (A) and salt (B) other than fluoride salt>
As the salt (B) other than the fluoride salt (A) and the fluoride salt described above, the salt (B) other than the fluoride salt (A) and the fluoride salt made of the same base are used from the viewpoint of controlling dissociation equilibrium. It is preferable to use in combination. Among these, a combination of ammonium fluoride (A1) and an ammonium salt (B1) other than a fluoride salt, and a combination of a fluoride amine (A2) and an amine salt (B2) other than a fluoride salt are preferable.

In addition, in order to efficiently generate HF ²⁻ , suppress side etching of the insulating film, and improve residue removability, ammonium fluoride (A1), amine fluoride (A2), tetraalkylammonium fluoride At least one fluoride salt (A) selected from the group consisting of (A3), ammonium salt (B1) other than fluoride salt, amine salt (B2) other than fluoride salt, and tetraalkyl other than fluoride salt The mixing ratio with the salt (B) other than at least one fluoride salt selected from the group consisting of the ammonium salt (B3) is a molar ratio of (A) :( B) = 3: 1 to 1: 3. A range is preferred.

<PH of residue removing solution>
The pH of the residue removing solution after the dry process of the present invention needs to be adjusted so that the insulating film is etched and no step is generated in the multilayer portion. If the insulating film is structurally weak, if the pH is less than 7, a large amount of HF is generated in the residue removal solution, the insulating film is easily side-etched, and a structure as designed cannot be formed. Therefore, regardless of the type of insulating film, it is necessary to have a pH of 7 or higher in order to suppress etching. Preferably it is pH 7-9, More preferably, it is pH 7-8.5, Most preferably, it is pH 7.5-8.5. If the pH exceeds 9, the treatment time for removing the residue becomes long, and the back surface of the silicon wafer is likely to be etched, which is not preferable.
<Other ingredients>
Furthermore, it is possible to add a more excellent function by adding a surfactant, an organic solvent or the like as necessary.

  The surfactant increases wettability with respect to the hydrophobic interlayer insulating film and can be used to prevent the case where the residue removing liquid does not spread depending on the shape of the pattern. The kind is not specifically limited, such as a cation system, an anion system, and a nonionic system.

Specifically, examples of the cationic surfactant include a primary amine represented by RNH ₂ , a secondary amine represented by R ₂ NH, a tertiary amine represented by R ₃ N, [R ₄ N] A quaternary amine represented by _M (R represents a linear or branched alkyl group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom, a fluorine atom or an OH group, or a fluorine atom or an OH group. Phenyl group which may be substituted; M is a monovalent anion). Specifically, CH ₃ (CH ₂ ) _n NH ₂ , (CH ₃ (CH ₂ ) _n ) ₂ NH, (CH ₃ (CH ₂ ) _n ) ₃ N, (CH ₃ (CH ₂ ) _n ) ₄ NCl _{, CH 3 (CH 2) n} n ((CH 2) n OH) 2, CF 3 (CF 2) n NH 2, (CF 3 (CF 2) n) 2 NH, (CF 3 (CF 2) n) ₃ N, (CF ₃ (CF ₂ ) _n ) ₄ NCl, CF ₃ (CF ₂ ) _n N ((CH ₂ ) _n OH) ₂ , C ₆ H ₅ NH ₂ , (CH ₃ ) ₂ (CH ₂ ) _n NH ₂ (n is an integer of 1 to 30.), and the like.

Examples of the anionic surfactant include a carboxylic acid type, a sulfonic acid type, or a sulfate ester whose hydrophilic group is —COOM, —SO ₃ M, —OSO ₃ M (M is a hydrogen atom, a metal atom, or an ammonium group). A type of surfactant is preferred.

Specific examples of the carboxylic acid type surfactant include CF ₃ (CF ₂ ) _n COOH, (CF ₃ ) ₂ CF (CF ₂ ) _n COOH, HCF ₂ (CF ₂ ) _n COOH, CF ₃ (CF _{2 ) n (CH 2) m COOH} , CF 3 (CF 2) n CF = CH (CH 2) m COOH, Cl (CF 2 CFCl) p CF 2 COOH (n is 2 to 17, m is 1 to 2, p And an alkali metal salt, ammonium salt, primary amine salt, secondary amine salt, tertiary amine salt, and the like.

Examples of the sulfonic acid type surfactant and the sulfate ester type surfactant include C _n H _{2n + 1} SO ₃ M, C _n H _{2n + 1} O (CH ₂ CH ₂ O) _m SO ₃ M, and C _n H _{2n + 1} PhSO. ₃ M, C _n H _{2n + 1} PhO (CH ₂ CH ₂ O) _m SO ₃ M or C _n H _{2n + 1} Ph (SO ₃ H) OPhSO ₃ M (M is a hydrogen atom, metal atom or ammonium group; Ph is a phenylene group; n is an integer of 5-20; m is an integer of 0-20). Examples of _{these, C 12 H 25 O (CH} 2 CH 2 O) 2 SO 3 H, C 9 H 19 PhO (CH 2 CH 2 O) 4 SO 3 H, C 12 H 25 O (CH 2 CH ₂ O) ₄ SO ₃ H, C ₆ F ₁₁ PhSO ₃ H, C ₉ F ₁₇ OPhSO ₃ H, RCH═CH (CH ₂ ) _n SO ₃ H (R represents a hydrogen atom substituted with a fluorine atom. C ₁₂ H ₂₅ OSO ₃ H, C ₁₂ H ₂₅ Ph (SO ₃ H) OPhSO ₃ H, and their metal salts, ammonium salts, primary amine salts, Examples thereof include amine salts and tertiary amine salts.

As the nonionic surfactant, a hydrophilic group is —R ′ (CH ₂ CH ₂ O) _q R ″ or —R′O (CH ₂ CH ₂ O) _q R ″ (R ″ is a hydrogen atom having 1 carbon atom) -10 alkyl group; R ′ is a polyethylene glycol type interface represented by a hydrogen atom in which a hydrogen atom may be substituted with a fluorine atom; and q is an integer of 0-20) Activators are preferred, specifically C ₉ F ₁₇ O (CH ₂ CH ₂ O) _r CH ₃ (r is an integer from 2 to 30), C ₉ H ₁₉ Ph (CH ₂ CH ₂ O) ₁₀ H, C ₁₂ H ₂₅ O (CH ₂ CH ₂ O) ₉ H, C ₉ H ₁₉ PhO (CH ₂ CH ₂ O) ₁₀ H, C ₉ H ₁₉ PhO (CH ₂ CH ₂ O) ₅ H, C ₈ H _{17 PhO (CH 2 CH 2 O} ) 3 H, C 8 H 17 Ph (CH 2 C _{2 O)} 10 H (Ph can be mentioned a is) such as a phenylene group.

  The compounding amount (concentration) of the surfactant is generally 0.00001 to 5% by weight, preferably 0.0001 to 3% by weight in the residue removing solution. If the amount is less than 0.00001% by weight, the surfactant effect tends to be small, and even if the amount is more than 5% by weight, the change in the effect tends to be small.

An organic solvent can be used to facilitate removal of the organic component when it is present in the residue. The organic solvent is not particularly limited, but an organic solvent that does not dissociate H ⁺ (proton) and has a high donor number is preferable. Examples thereof include sulfoxides such as dimethyl sulfoxide (DMSO), amides such as dimethylformamide (DMF), dimethylacetamide (DMA), and N-methylpyrrolidone (NMP).

  The amount (concentration) of the organic solvent is generally about 1 to 40% by weight in the residue removing solution. Preferably it is 3 to 20 weight%, More preferably, it is 5 to 10 weight%.

  The ratio of water contained in the residue removing liquid of the present invention is usually about 30 to 95% by weight, preferably about 40 to 80% by weight in the residue removing liquid, and is determined according to the amount of components other than water. be able to.

<Preferred composition>
Below, a specific preferable residue removal liquid is illustrated.

  For example, at least one fluoride salt (A) selected from the group consisting of ammonium fluoride (A1), fluoride amine (A2), and tetraalkylammonium fluoride (A3) and an ammonium salt other than the fluoride salt (B1) ), An amine salt (B2) other than a fluoride salt, a salt (B) other than at least one fluoride salt selected from the group consisting of a tetraalkylammonium salt (B3) other than a fluoride salt, and water (C) In the case of a residue-removing solution containing a salt, the blending amount (concentration) of the fluoride salt (A) is about 6 to 60% by weight (preferably about 15 to 40% by weight), and the salt (B) other than the fluoride salt is 4 to 4%. About 50% by weight (preferably about 10-25% by weight), and the rest is water (C). The preferred pH of this residue removal solution is about 7-9 (preferably about 7-8).

  For example, at least one fluoride salt (A) selected from the group consisting of ammonium fluoride (A1), fluoride amine (A2), and tetraalkylammonium fluoride (A3) and an ammonium salt other than the fluoride salt (B1) ), An amine salt (B2) other than a fluoride salt, a salt (B) other than at least one fluoride salt selected from the group consisting of a tetraalkylammonium salt (B3) other than a fluoride salt, and water (C) In the case of a residue removing solution containing an organic solvent, the blending amount of the fluoride salt (A) is about 6 to 60% by weight (preferably about 15 to 40% by weight), and the salt (B) other than the fluoride salt is 4 to 4%. About 50% by weight (preferably about 10-25% by weight), the amount of the organic solvent is about 1-40% by weight (preferably about 3-20% by weight), and the rest is water (C). The pH of this residue removal solution is about 7-9 (preferably about 7-8). As the organic solvent, DMSO, DMF, DMA and the like are suitable.

For example, at least one fluoride salt (A) selected from the group consisting of ammonium fluoride (A1), fluoride amine (A2), and tetraalkylammonium fluoride (A3) and an ammonium salt other than the fluoride salt (B1) ), An amine salt (B2) other than a fluoride salt, a salt (B) other than at least one fluoride salt selected from the group consisting of a tetraalkylammonium salt (B3) other than a fluoride salt, and water (C) In the case of a residue removing solution containing a surfactant, the blending amount of the fluoride salt (A) is about 10 to 60% by weight (preferably about 15 to 40% by weight), and the salt (B) other than the fluoride salt is 4 ˜50% by weight (preferably about 5 to 35% by weight), the compounding amount of the surfactant is about 0.00001 to 5% by weight (preferably about 0.0001 to 3% by weight), and the rest is water (C) It is. The pH of this residue removal solution is about 7-9 (preferably about 7-8). As the surfactant, C ₁₂ H ₂₅ Ph (SO ₃ H) OPh (SO ₃ H) (Ph is a phenylene group), ammonium salts thereof, and the like are suitable.
II. Object to be processed in the residue-removing liquid to be removed residues present invention, the oxide film formed on the nickel silicide (NiSi) to be mainly removed, the residue after dry pro process, and NiSi surface to be protected is there.

  NiSi oxide film includes NiSi oxide formed during dry etching and / or ashing, or NiSi natural oxide film formed by natural oxidation of metal when exposed to the atmosphere due to movement between processes, etc. Is mentioned. These compositions contain a large amount of NiO, SiO and the like.

  Residues after dry pro-process are NiSi oxide film on NiSi surface of NiSi structure and / or NiSi oxide formed by dry etching and / or ashing on wafers formed using NiSi as conductive metal It consists of NiSi alteration material containing a thing. This residue adheres mainly to NiSi on which the pattern is formed, to the side wall of the pattern formed of an insulating film such as a silicon oxide film or a silicon nitride film, and to the surface of the interlayer insulating film substrate.

  Residue formed on NiSi is an altered residue composed of a mixture of NiSi oxide and NiSi that has been damaged and oxidized and / or fluorinated by dry etching and / or ashing, and its electrical resistance increases. It is a thing. Since this NiSi alteration is made of oxidized and / or fluorinated NiSi oxide and NiSi, the electric resistance is an insulating layer close to NiO and SiO.

  Residue adhering to the side wall of the pattern formed of an insulating film such as a silicon oxide film or a silicon nitride film may be obtained by sputtering NiSi itself by dry etching in addition to the NiSi alteration, and contains Si and Ni. There is a case. Residues on the surface of the interlayer insulating film substrate are not removed by ashing into residues in processes using organic substances such as resists, antireflection films and filling agents, and inorganic masks, which are not removed by ashing. It can be inferred that it contains some Si, Ni, and NiSi alterations flying from the bottom of the trench.

  In this specification, the insulating film is mainly a silicon oxide film (SiO) and this doped film, a silicon nitride film (SiN), a low-k film, a porous-low-k film, etc. Also included is a silicon oxide film (FSG film) containing. The silicon oxide film does not depend on its manufacturing method such as plasma, coating, or heat.

  The low-k film and the porous-low-k film are insulating films having a relative dielectric constant greater than 1 and about 4 or less, preferably about 3 or less, more preferably about 2.8 or less, and even more preferably about 2.6 or less. Means. The Low-k film is mainly generated by coating or plasma CVD.

Specifically, the LKD series (trade name, manufactured by JSR Corporation), the HSG series (trade name, manufactured by Hitachi Chemical Co., Ltd.), Nanoglass (trade name, manufactured by Honeywell), IPS (trade name, catalyst chemical conversion) Kogyo Co., Ltd.), Z ₃ M (trade name, manufactured by Dow Corning), XLK (trade name, manufactured by Dow Corning), FO _x (trade name, manufactured by Dow Corning), Orion (trade name, Tricon) Manufactured), NCS (trade name, manufactured by Catalyst Chemical Industry Co., Ltd.), SiLK, porous-SiLK (trade name, manufactured by Dow Corning), etc., inorganic SOG (HSG: hydrogenated silsesquioxane), organic SOG film ( MSQ film: methylsilsesquioxane film), coating film called organic polymer film mainly composed of polyallyl ether, etc. There are plasma CVD films represented by diamond (trade name, manufactured by Applied Materials), coral (trade name, manufactured by Novellus), aurora (trade name, manufactured by ASM), etc., but are not limited thereto. Absent.

Examples of the resist include, but are not limited to, KrF (krypton F), ArF, and F ₂ resist.
III. Removal of NiSi Oxide and / or Residue After Dry Process The residue removal method of the present invention is mainly a method for removing a residue present in a semiconductor substrate having NiSi. Specifically, a semiconductor having a current terminal electrode containing NiSi (nickel silicide) and having one or more interlayer insulating films of a silicon oxide film, a silicon nitride film, and a low dielectric constant film (Low-k film) The residue after the dry process existing on the substrate is removed by using the residue removing liquid.

  The present invention also provides a method for manufacturing a semiconductor device. The manufacturing method includes (1) a current terminal electrode containing nickel silicide (NiSi), and at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, and a low dielectric constant film (Low-k film). The method includes a step of dry etching and / or ashing a semiconductor substrate having an interlayer insulating film, and (2) a step of bringing the semiconductor substrate treated in the above (1) into contact with the above residue removing liquid.

  The residue removal process is performed by bringing a semiconductor substrate, which is an object to be processed, into contact with a residue removal solution. The method of contacting the residue removing liquid is not particularly limited as long as NiSi oxide and / or residues after the dry process can be removed, NiSi corrosion is suppressed, and the insulating film is not substantially damaged. However, it can be appropriately set according to conditions such as the target residue, the type of the residue removal liquid, and the temperature.

  As the contact method, for example, a batch type in which a large amount of processing object (wafer) contained in a cassette is immersed in a tank for storing the residue removal liquid, and a residue removal liquid is applied from above the rotated processing object (wafer). Various contact methods, such as a single wafer type that is washed over and a spray type in which a residue removing solution is continuously sprayed on the object to be processed (wafer) by spraying, are used.

  The temperature of the residue removing solution is, for example, about 10 to 60 ° C, preferably about 15 to 40 ° C. The contact time is not limited and can be appropriately selected. For example, the contact time is about 0.5 to 30 minutes, preferably about 1 to 15 minutes.

  Moreover, in the case of a batch type, you may immerse a wafer in the residue removal liquid under stirring as needed. The speed of stirring is not limited and can be appropriately selected. In the case where it is difficult to remove unnecessary substances, for example, the object to be treated may be immersed in a residue removing solution and subjected to ultrasonic cleaning. The ultrasonic wave should just be 80 kHz or more, Preferably it is 80 kHz-10 MHz, for example, 100 kHz-3 MHz.

  The NiSi oxide removal method of the present invention can be further performed by washing the wafer from which the NiSi oxide and / or the residue after the dry process has been removed with pure water. The residue removing solution of the present invention can be washed away by this washing step.

  The semiconductor substrate from which the NiSi oxide and / or the residue after the dry process has been removed using the residue removing solution of the present invention can be processed into various types of semiconductor devices (devices).

  Examples are given below to clarify the features of the invention. The present invention is not limited to these examples.

  A wafer with a test pattern having a NiSi structure in which contact holes were formed was used. The wafer has an insulating film in which an NSG (SiO film formed by atmospheric pressure CVD), a silicon nitride film SiN, and a P-SiO film (SiO film formed by plasma) are sequentially stacked on a NiSi substrate.

  The wafer with the test pattern was dry-etched with fluorocarbon plasma and then ashed with oxygen plasma. A large amount of residue after the dry process is present at the bottom of the via hole and is slightly observed on the side wall of the via hole and the surface of the low-k substrate.

  The wafer with the test pattern was immersed in the chemical solutions shown in the examples and comparative examples with stirring (about 600 rpm) for a predetermined time. Then, the residue removal process after a dry process was performed by rinsing and drying with running ultrapure water.

  After this residue removal treatment, the contact hole was observed for residue removal and cross-sectional shape with an electron microscope (SEM).

  Table 1 shows the determination criteria for the test results.

Examples 1-20
The residue removal liquid of Examples 1-20 was prepared with the composition and compounding ratio of Table 2. Table 2 also shows the immersion temperature and time of the wafer with the test pattern in the residue removal solution. The pH of all the residue removal solutions was adjusted to be in the range of 7.5 to 8.5.

  Table 3 shows the results of tests using the residue removal solutions of Examples 1-20.

  From Tables 2 and 3, when the experiment was performed using the residue removing solutions of Examples 1 to 20, both evaluations were excellent.

Example 21
When 500 ppm of C ₁₂ H ₂₅ Ph (SO ₃ NH ₄ ) OPh (SO ₃ NH ₄ ) was added to the residue removal solution of Example 15, the residue removal time could be shortened from 5 minutes to 4 minutes.

Comparative Examples 1-11
The chemical solutions of Comparative Examples 1 to 11 were prepared with the compositions and blending ratios shown in Table 4. Table 4 also shows the immersion temperature and time of the test pattern wafer in the chemical solution. The pH of all the chemicals was adjusted to be in the range of 7.5 to 8.5.

  Table 5 shows the results of testing using the chemical solutions of Comparative Examples 1 to 11.

In Comparative Examples 1 to 3, since there is little F ⁻ and HF ₂ ⁻ cannot be generated, residue removability is poor. Further, side etching is likely to occur in the insulating film due to the generated HF.

  In Comparative Examples 4-7, since there is no fluorine compound, residue removal property is bad.

In Comparative Examples 8 to 11, since a salt other than fluoride exists, side etching of the insulating film is suppressed. However, since the amount of fluoride ions (F ⁻ ) is insufficient, residue removability is poor.

Claims (15)

A solution for removing residues present after dry etching and / or ashing a semiconductor substrate containing nickel silicide (NiSi),
(A) at least one fluoride salt selected from the group consisting of ammonium fluoride (A1), amine fluoride (A2), and tetraalkylammonium fluoride (A3);
(B) At least one fluoride salt selected from the group consisting of ammonium salts other than fluoride salts (B1), amine salts other than fluoride salts (B2), and tetraalkylammonium salts other than fluoride salts (B3) Including salt other than (C) water,
Concentration of fluoride salt (A) is 5% by weight or more, concentration of salt (B) other than fluoride salt is 3% by weight or more, tetraalkylammonium fluoride (A3) and tetraalkylammonium salt other than fluoride salt ( Residue removing liquid having a total concentration of B3) of less than 15% by weight and a pH of 7-9. The residue removing liquid according to claim 1, wherein the fluorinated amine (A2) is at least one selected from the group consisting of fluorinated methylamine, fluorinated ethylamine, and fluorinated butylamine. The residue removing liquid according to claim 1 or 2, wherein the tetraalkylammonium fluoride (A3) is at least one selected from the group consisting of tetramethylammonium fluoride, tetraethylammonium fluoride, and tetrabutylammonium fluoride. The residue removing solution according to any one of claims 1 to 3, wherein the salt (B) other than the fluoride salt is a salt of a weak acid having a pKa of 4 or more. The residue removing solution according to claim 4, wherein the salt of the weak acid is at least one selected from the group consisting of an ammonium salt of a monocarboxylic acid, an amine salt of a monocarboxylic acid, and a tetraalkylammonium salt of a monocarboxylic acid. The residue removing solution according to claim 4 or 5, wherein the salt of the weak acid is at least one selected from the group consisting of ammonium acetate, methylamine acetate, ethylamine acetate and tetramethylammonium acetate. The residue removal liquid according to any one of claims 1 to 3, wherein the tetraalkylammonium salt (B3) other than the fluoride salt is at least one selected from the group consisting of tetraalkylammonium chloride and tetraalkylammonium acetate. The residue removing liquid according to claim 1, wherein the salt (B) other than the fluoride salt is a salt composed of the same base as the fluoride salt (A). The residue according to any one of claims 1 to 8, wherein the fluoride salt (A) is ammonium fluoride (A1), and the salt (B) other than the fluoride salt is an ammonium salt (B1) other than the fluoride salt. Remover. The residue according to any one of claims 1 to 8, wherein the fluoride salt (A) is a fluorinated amine (A2), and the salt (B) other than the fluoride salt is an amine salt (B2) other than the fluoride salt. Remover. Furthermore, the residue removal liquid in any one of Claims 1-10 containing surfactant. Furthermore, the residue removal liquid in any one of Claims 1-11 containing an organic solvent. A method of removing residues present after dry etching and / or ashing a semiconductor substrate containing nickel silicide (NiSi),
A method for removing a residue, comprising bringing the semiconductor substrate after the dry etching and / or ashing into contact with the residue removing solution according to claim 1. The semiconductor substrate has a current terminal electrode containing nickel silicide (NiSi), and at least one interlayer insulating film selected from the group consisting of a silicon oxide film, a silicon nitride film, and a low dielectric constant film (Low-k film) The residue removal method of Claim 13 which has these. (1) It has a current terminal electrode containing nickel silicide (NiSi) and has at least one interlayer insulating film selected from the group consisting of a silicon oxide film, a silicon nitride film, and a low dielectric constant film (Low-k film). A step of dry etching and / or ashing the semiconductor substrate, and (2) a step of bringing the semiconductor substrate treated in the above (1) into contact with the residue removing liquid according to any one of claims 1 to 12. A method for manufacturing a semiconductor device.