JP2009176818A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device which includes a silicide film having excellent performance by suppressing damages to the silicide film during manufacture step. <P>SOLUTION: The method of manufacturing a semiconductor device includes: a step (a) to form an alloy film 13 on a substrate 11; a step (b) to form a silicide film 14 by heating the substrate 11; a step (c) to supply a first solution 15 to the substrate 11 and dissolve Ni included in such a part of the alloy film 13 that is not reacted and is left on the substrate 11; a step (d) to supply a second solution 18 to the substrate 11 and form a protective film 19 on the silicide film 14; and a step (e) to supply a third solution 16 containing hydrochloric acid to the substrate 11 and dissolve a metal 17 remaining on the substrate 11. In the step (c), Ni in the silicide film is reacted with the second solution 18, so as to form the protective film 19 made of complex. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device having a silicide film.

  In a CMOS (Complementary Metal Oxide Semiconductor) micro process, further higher performance and lower power consumption of a device are required. In the conventional CMOS process, for example, NiSi or CoSi using Ni or Co has been used as a silicide material in order to reduce the silicide resistance. However, in the fine process, it is necessary to suppress the silicide reaction between Ni and Co and Si in order to reduce the junction leakage current. Therefore, an alloy in which, for example, Pt or Pd is mixed with Ni or Co is used as a silicide material. In particular, when an alloy of Ni and Pt (NiPt) is used as a silicide material, effects such as improvement of heat resistance and suppression of junction leakage current are expected.

  In the silicidation step, an alloy is formed on a Si substrate and then subjected to a thermal oxidation treatment to react the alloy with Si to form silicide, but it is necessary to remove the unreacted alloy. Here, for example, when an alloy of Ni and Pt (NiPt) is used as the silicide material, an acid having an oxidizing power such as a mixed solution of sulfuric acid and hydrogen peroxide is used to remove unreacted NiPt after the formation of the silicide. Then, while Ni is dissolved, Pt which is a hardly soluble substance remains on the substrate without being dissolved. For this reason, it is necessary to dissolve Pt with a strong acid containing chlorine, which is a strong etchant component, such as a mixed acid solution of nitric acid and hydrochloric acid (see, for example, Patent Document 1).

  Here, a conventional silicidation process in which an alloy of Ni and Pt (NiPt) is used as a silicide material and unreacted Pt is dissolved with a strong acid will be described with reference to FIG. 7A and 7B are cross-sectional views showing a silicidation process of a conventional semiconductor device.

  First, as shown in FIG. 7A, an insulating film 72 is formed on a region (non-silicide region) excluding a silicide region, in which a silicide film is formed, of a semiconductor substrate 71 made of silicon. Next, a NiPt alloy film 73 is formed on the entire surface of the semiconductor substrate 71 as a silicide film material. Thereafter, a heat treatment is performed on the semiconductor substrate 71 to form a mixed crystal silicide film 74 made of NiSi and NiPtSi in the silicide region.

Next, as shown in FIG. 7B, the semiconductor substrate 71 is exposed to a mixed acid solution 75 of nitric acid and hydrochloric acid to dissolve the NiPt alloy film 73 remaining unreacted.
JP 2007-123527 A

  However, in the above prior art, when unreacted NiPt is dissolved by a mixed acid solution of nitric acid and hydrochloric acid, the surface of the silicide film 74 made of NiPtSi is corroded due to chlorine in the mixed acid solution. For this reason, in the silicide film 74, a minute unevenness (roughness) shape is generated on the surface, and variation in silicide resistance occurs.

  In view of the above problems, an object of the present invention is to provide a method of manufacturing a semiconductor device including a silicide film that is suppressed from being damaged during the manufacturing process and has good performance.

  In order to solve the above problems, a method of manufacturing a semiconductor device of the present invention includes a step (a) of forming an alloy film containing nickel and a metal having a smaller ionization tendency than nickel on a substrate made of silicon, (B) forming a silicide film by reacting the silicon and the alloy film by heat-treating the substrate; and supplying a first oxidizing solution to the substrate after the step (b). Then, after the step (c) of dissolving the nickel contained in the unreacted portion of the alloy film remaining on the substrate, a complex with the nickel is formed on the substrate after the step (c). And supplying a second solution containing the compound to be reacted and reacting the nickel contained in the silicide film with the compound to form a complex, thereby forming a protective film made of the complex on the silicide film. In step (d), by supplying a third solution containing hydrochloric acid to the substrate, the metal remaining on the substrate is dissolved in a state where the silicide film is covered with the protective film (e ).

  According to this method, after adding the first solution in step (c) to dissolve only nickel, the second solution and nickel contained in the silicide film react with each other in step (d) to form a complex. Thus, a protective film made of a complex is formed on the silicide film. Thereby, in the step (e), since the third solution containing chlorine is supplied in a state where the silicide film is covered with the protective film, the remaining metal is removed while suppressing the dissolution of nickel contained in the silicide film. Can be dissolved. As a result, unreacted metal can be removed while suppressing problems such as corrosion of the surface of the silicide film made of a nickel alloy by the third solution and generation of irregularities on the surface of the silicide film. Therefore, if the semiconductor device manufacturing method of the present invention is used, a silicide film made of a nickel alloy is not easily damaged during the manufacturing process, and even if it is miniaturized, a junction leakage current is suppressed, and a high performance having good heat resistance. A simple silicide film can be formed. Therefore, according to the method for manufacturing a semiconductor device of the present invention, a highly reliable semiconductor device including a silicide film made of a nickel alloy can be manufactured with a high yield.

  According to the method for manufacturing a semiconductor device of the present invention, since the silicide film is prevented from being damaged during the manufacturing process, it is possible to manufacture a highly reliable semiconductor device including a silicide film exhibiting good performance. it can.

(First embodiment)
A method for manufacturing a semiconductor device according to a first embodiment of the present invention will be described with reference to the drawings. 1A to 1D are cross-sectional views showing a method for manufacturing a semiconductor device of this embodiment.

  First, as shown in FIG. 1A, a silicon oxide film in which no impurity is introduced, for example, on a region (non-silicide region) excluding a silicide region for forming a silicide film in a semiconductor substrate 11 made of silicon. An insulating film 12 made of is formed with a film thickness of 20 nm to 70 nm. Thereafter, an alloy film 13 made of, for example, a NiPt alloy is formed to a thickness of 7 to 14 nm on the entire surface of the semiconductor substrate 11. Next, a thermal oxidation process is performed on the semiconductor substrate 11 at, for example, 200 ° C. to 400 ° C., thereby forming a silicide film 14 made of NiPtSi with a film thickness of, for example, 8.5 nm to 15.5 nm in the silicide region. In addition, the content of Pt in the NiPt alloy used for the alloy film 13 is, for example, 2 to 8 wt%.

Next, as shown in FIG. 1B, for example, a first solution 15 made of a mixed solution of sulfuric acid and hydrogen peroxide water and having oxidizing properties is applied to the semiconductor substrate 11 at a liquid temperature of 100 ° C. to 150 ° C. Supply. Thereby, Ni contained in the remaining part of the alloy film 13 without reacting with Si in the step of FIG. At this time, Pt contained in the unreacted portion of the alloy film 13 is not dissolved but remains as a residue 17 on the non-silicide region of the semiconductor substrate 11. The mixed solution of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide solution (H ₂ O ₂ ) has a concentration ratio in the range of H ₂ SO ₄ : H ₂ O ₂ = 1: 1 to 5: 1, for example. is there.

Next, as shown in FIG. 1C, diluted ammonia water is supplied to the semiconductor substrate 11 as the second solution 18 at a liquid temperature of 25 ° C. to 50 ° C. Thereby, the complex of [Ni (NH ₃ ) ₆ ] ²⁺ is selectively generated by the reaction between the amino group of the diluted ammonia water and Ni contained in the surface of the silicide film 14. As a result, a protective film 19 made of [Ni (NH ₃ ) ₆ ] (OH) ₂ is formed on the silicide film 14. At this time, the Pt residue 17 remains in the non-silicide region. The diluted ammonia water used as the second solution 18 has a pH of 7 or more and 9 or less, for example.

Next, as shown in FIG. 1D, as the third solution 16, for example, a mixed solution of nitric acid and hydrochloric acid is supplied to the semiconductor substrate 11 at a liquid temperature of 30 ° C. to 60 ° C. As a result, the Pt residue 17 remaining on the non-silicide region is dissolved. At this time, since the surface of the silicide film 14 is covered with the protective film 19, dissolution of Ni in the silicide film 14 by the third solution 16 containing hydrochloric acid is suppressed. The mixed solution of nitric acid and hydrochloric acid has a concentration ratio in the range of HNO ₃ : HCl = 1: 1 to 1: 3, for example.

  Subsequently, although not shown, the protective film 19 made of a complex is removed. As a method for removing the protective film 19, for example, a cleaning process is performed for 3 minutes or more using hot water having a temperature of 70 ° C. or higher and 90 ° C. or lower, or a range of 150 ° C. or higher and 250 ° C. or lower. A method of thermally oxidizing the semiconductor substrate 11 at a temperature of Note that this step is not necessarily performed. For example, when an interlayer insulating film is formed on the semiconductor substrate 11 in the following steps, the film is usually formed at a temperature of 300 ° C. or higher. It is possible to remove the protective film 19 made of a complex. Therefore, in the manufacturing method of the present embodiment, the protective film 19 is removed without providing a special processing step for removing the protective film 19, so that the device characteristics are deteriorated due to the influence of the remaining protective film 19. Can be prevented.

  The semiconductor device manufacturing method of the present embodiment is characterized in that, in the step shown in FIG. 1B, after supplying the first solution 15 for selectively dissolving Ni contained in the alloy film 13, FIG. The second solution 18 capable of reacting with Ni in the silicide film 14 to form a complex is supplied in the step shown in FIG. According to this method, after removing only Ni contained in the unreacted remaining portion of the alloy film 13 by the first solution 15, the second solution 18 reacts with Ni in the silicide film 14. A complex is generated, and a protective film 19 made of the complex is formed on the silicide film 14. Thereby, in the process shown in FIG. 1D, since the third solution 16 containing chlorine is supplied in a state where the silicide film 14 is covered with the protective film 19, the dissolution of Ni contained in the silicide film 14 is prevented. Pt remaining unreacted can be dissolved while being suppressed. As a result, the surface of the silicide film 14 made of a nickel alloy is corroded by the third solution 16 and unevenness is generated on the surface of the silicide film 14 while suppressing the unreacted alloy film 13. can do. Therefore, if the semiconductor device manufacturing method of the present embodiment is used, the silicide film made of a nickel alloy is not easily damaged during the manufacturing process, and even if the silicide film is miniaturized, the junction leakage current is suppressed and high heat resistance is obtained. A high performance silicide film can be formed. Therefore, in the semiconductor device manufacturing method of the present embodiment, a highly reliable semiconductor device including a silicide film made of a nickel alloy can be manufactured with a high yield.

Here, the reason why dissolution of Ni in the protective film 19 is suppressed in the step shown in FIG. 1D when the protective film 19 made of [Ni (NH ₃ ) ₆ ] (OH) ₂ is formed will be described below. Explained.

When nickel reacts with ammonia (NH ₃ ) water, a non-shared electron pair of NH ₃ is coordinated with Ni to form a covalent bond, thereby generating a complex [Ni (NH ₃ ) ₆ ] ²⁺ . On the other hand, when Ni reacts with hydrochloric acid, nickel ions (Ni ²⁺ ) and chloride ions (Cl ⁻ ) are ion-bonded by electrostatic attraction to produce NiCl ₂ . In general, covalent bonds are stronger and more stable than ionic bonds. Therefore, even when hydrochloric acid is supplied to the complex [Ni (NH ₃ ) ₆ ] ²⁺ having a strong covalent bond, the reaction between nickel and Cl ⁻ does not proceed easily. Accordingly, even if the third solution 16 containing hydrochloric acid is supplied in the step shown in FIG. 1D, the elution of nickel contained in the protective film 19 made of a complex is suppressed, and the silicide film 14 is sufficient for the protective film 19. Therefore, it is possible to prevent a problem such that nickel in the silicide film 14 is eluted and irregularities are formed on the surface of the silicide film 14.

  In the semiconductor device manufacturing method of the present embodiment, a mixed solution of sulfuric acid and hydrogen peroxide is used as the first solution 15, but the present invention is not limited to this, and any solution having oxidizing properties may be used. That's fine. In particular, a mixed solution of any one of sulfuric acid, nitric acid, acetic acid, or phosphoric acid and hydrogen peroxide is preferable because the metal (nickel) contained in the alloy film 13 remaining unreacted can be efficiently dissolved. .

As the second solution 18, a solution containing a compound that forms a complex with nickel is used. Here, it is preferable to use a solution having an amino group as the second solution 18 because it easily reacts with Ni to form a complex. In this case, the pH of the second solution 18 is preferably in the range of 7 or more and 9 or less. The solution having an amino group is not limited to ammonia water. For example, methylamine (CH ₃ NH ₂ ) water, ethylamine (CH ₃ CH ₂ NH ₂ ) water, hexamethylene diamine (H ₂ N— Even when a solution such as (CH ₂ ) ₆ -NH ₂ ) water, tetramethylethylenediamine ((CH ₃ ) ₂ NCH ₂ CH ₂ N (CH ₃ ) ₂ ) water is used, the same effect as the manufacturing method of the present embodiment is achieved. Is obtained.

  The third solution 16 is not limited to a mixed acid solution of hydrochloric acid and nitric acid, and may be any solution that can dissolve Pt. For example, even when a mixed solution of hydrochloric acid and hydrogen peroxide, or simply using hydrochloric acid, is used instead of the mixed acid solution of hydrochloric acid and nitric acid, the same effect as the manufacturing method of the present embodiment can be obtained. In addition, when using only hydrochloric acid, you may use what added water to concentrated hydrochloric acid, for example.

  Below, the effect of the manufacturing method of the semiconductor device of this embodiment is demonstrated. FIG. 2 is a diagram showing the evaluation results of the thickness of the silicide film according to the method for manufacturing the semiconductor device of the present embodiment. FIG. 3 shows the evaluation results of the resistance value of the silicide film according to the method for manufacturing the semiconductor device of this embodiment.

  FIG. 2A shows a conventional method in which a step of forming a silicide film (silicide film formation) and a step of removing an unreacted alloy film using a mixed acid solution of nitric acid and hydrochloric acid (mixed acid solution treatment) are performed. These are the results of measuring the thickness of the silicide film after each step. 2B shows a step of forming the silicide film shown in FIG. 1A (silicide film formation) and the sulfuric acid and hydrogen peroxide shown in FIG. 1B according to the method for manufacturing the semiconductor device of the present embodiment. In the step of supplying the mixed solution (mixed solution treatment) and the step of supplying the mixed acid solution of nitric acid and hydrochloric acid (mixed acid solution treatment) shown in FIG. 1C, the thickness of the silicide film was measured after each step. It is a result.

As shown in FIG. 2, in the conventional method A, when the treatment is performed with a mixed acid solution of nitric acid and hydrochloric acid, the thickness of the silicide film is reduced by about 2.5 nm compared to the thickness after the silicide film is formed. This decrease in film thickness is thought to be because Ni contained in the silicide film reacted with hydrochloric acid to be dissolved as Ni ²⁺ . On the other hand, in the semiconductor device manufacturing method B of the present embodiment, even after the mixed acid solution treatment, the thickness of the silicide film is hardly changed compared to the thickness after the silicide film is formed. This is thought to be because, unlike the conventional method, the nickel elution phenomenon in which Ni on the surface of the silicide film reacts with hydrochloric acid to become Ni ²⁺ is suppressed.

  FIG. 3 shows the results of evaluating the variation in the sheet resistance value of the silicide film according to the method for manufacturing the semiconductor device of the present embodiment. A shown in FIG. 3 is a result of preparing a plurality of silicide films formed by using the conventional method and measuring the sheet resistance values of the plurality of samples in the same manner as A shown in FIG. B shown in FIG. 3 is a result of preparing a plurality of silicide film samples formed by using the manufacturing method of the present embodiment and measuring the sheet resistance values of the plurality of samples. As shown in FIG. 3, the sheet resistance value of the silicide film manufactured by the conventional method A varies greatly, but the sheet resistance value of the silicide film manufactured by the manufacturing method B of the present embodiment hardly varies. Specifically, in the manufacturing method B of the present embodiment compared to the conventional method A, the uniformity of the variation in the sheet resistance value of the silicide film is improved by 86%. Here, a detailed calculation method of the uniformity X (%) of the variation will be described below.

The variation uniformity X (%) is calculated by Equation 1 using the maximum value, the minimum value, and the average value among the measurement results of the sheet resistance values of a plurality of samples.
X (%) = 1/2 × (maximum value−minimum value) / average value × 100 (Expression 1)
This equation 1, the conventional methods uniformity of dispersion of the sheet resistance value in _A X A _(%), the uniformity X _{B (%)} of the variation in the sheet resistance value in the production method B of the present embodiment the the respectively obtained , X _A (%) = 1/2 × (270000-20000) /84000×100=148.8 (%), X _B (%) = 1/2 × (30000−2000) / 24000 × 100 = 20. 8 (%). Therefore, the improvement rate (%) of variation uniformity in the manufacturing method B of this embodiment with respect to the conventional method A is [(X _A −X _B ) / X _A ] × 100 = [(148.8-20. 8) /148.8] × 100 = 86 (%).

  In the manufacturing method B of the present embodiment, a silicide film having a lower resistance than that of the conventional manufacturing method A can be obtained. From the above results, by using the semiconductor device manufacturing method of this embodiment, it is possible to stably form a silicide film having a relatively low resistance and good performance, and to improve a highly reliable semiconductor device with a high yield. it can.

(Second Embodiment)
A method of manufacturing a semiconductor device according to the second embodiment of the present invention will be described with reference to the drawings. 4A to 4D are cross-sectional views showing a method for manufacturing the semiconductor device of this embodiment.

  First, as shown in FIG. 4A, an insulating film 42 made of, for example, a silicon oxide film into which no impurity is introduced is formed on a non-silicide region in which no silicide film is formed in a semiconductor substrate 41 made of silicon. The film is formed with a thickness of 20 to 70 nm. Thereafter, an alloy film 43 made of, for example, a NiPt alloy is formed on the entire surface of the semiconductor substrate 41 with a film thickness of 7 to 14 nm. Next, the semiconductor substrate 41 is subjected to, for example, a thermal oxidation process at 200 ° C. to 400 ° C. to form a silicide film 44 made of NiPtSi with a film thickness of 8.5 nm to 15.5 nm, for example, in the silicide region. Note that the content of Pt in the NiPt alloy used for the alloy film 43 is, for example, 2 to 8 wt%.

Next, as shown in FIG. 4B, the first solution 45 made of, for example, a mixed solution of sulfuric acid and hydrogen peroxide solution and having an oxidizing property is transferred to the semiconductor substrate 41 at a liquid temperature of 100 ° C. to 150 ° C. Supply. Thereby, Ni contained in the remaining part of the alloy film 13 without reacting with Si in the step of FIG. 4A is dissolved. At this time, Pt contained in the unreacted portion of the alloy film 43 remains undissolved and remains as a residue 47 on the non-silicide region of the semiconductor substrate 41. The mixed solution of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide solution (H ₂ O ₂ ) has a concentration ratio in the range of H ₂ SO ₄ : H ₂ O ₂ = 1: 1 to 5: 1, for example. is there.

Next, as shown in FIG. 4C, as the second solution 46, for example, NaCN (sodium cyanide) is used in a diluted solution of a mixed acid solution of hydrochloric acid and nitric acid, for example, so that the concentration is in the range of 1 ppm to 100 ppm. The mixed solution is supplied to the semiconductor substrate 41. At this time, the mixed acid solution of hydrochloric acid and nitric acid has, for example, a liquid temperature of 30 to 60 ° C. and a concentration ratio of HNO ₃ : HCl = 1: 1 to 1: 3. In this step, a mixed solution obtained by adding NaCN to a mixed acid solution of hydrochloric acid and nitric acid is used as the second solution 46, whereby the cyano group (CN ⁻ ) reacts with Ni contained in the silicide film 44, thereby [ A complex composed of Ni (CN) ₄ ] ²⁻ is selectively formed. As a result, a protective film 48 made of H ₂ [Ni (CN) ₄ ] and Na ₂ [Ni (CN) ₄ ] is formed on the silicide film 44. At this time, since the second solution 46 contains a mixed acid solution of hydrochloric acid and nitric acid, the protective film 48 is formed and the Pt residue 47 remaining in the non-silicide region is also dissolved. The reason why the formation of the protective film 48 and the dissolution of the residue 47 occur simultaneously in this step will be described later.

  Subsequently, although not shown, the protective film 48 made of a complex is removed. As a method for removing the protective film 48, for example, a cleaning process is performed for 3 minutes or more using hot water having a temperature of 70 ° C. or higher and 90 ° C. or lower, or a range of 150 ° C. or higher and 250 ° C. or lower. A method of thermally oxidizing the semiconductor substrate 41 at a temperature of Note that this step is not necessarily performed. For example, when an interlayer insulating film is formed on the semiconductor substrate 41 in the subsequent steps, the film formation is usually performed at a temperature of 300 ° C. or higher. Thus, the protective film 48 can be removed. Therefore, in the manufacturing method of the semiconductor device of this embodiment, the protective film 48 is removed without providing a special processing step for removing the protective film 48, so that the device characteristics are affected by the influence of the remaining protective film 48. Deterioration can be prevented.

  The semiconductor device manufacturing method of the present embodiment is characterized in that, in the step shown in FIG. 4B, after supplying the first solution 45 that selectively dissolves Ni contained in the alloy film 43, FIG. The second solution 46 capable of forming a complex by reacting with Ni in the silicide film 44 is supplied in the step shown in FIG. According to this method, similarly to the manufacturing method of the first embodiment, the first solution 45 removes only Ni contained in the unreacted portion of the alloy film 43 and then the second solution. 46 and Ni in the silicide film 44 react to form a complex, and a protective film 48 made of the complex is formed on the silicide film 44. Further, in the manufacturing method of the present embodiment, the second solution 46 includes a mixed acid solution of hydrochloric acid and nitric acid. Thereby, in the step shown in FIG. 4C, the unreacted Pt can be dissolved by the mixed acid solution of hydrochloric acid and nitric acid while forming the protective film 48 on the silicide film 44. As a result, it is possible to efficiently remove the unreacted alloy film 43 while suppressing problems such as corrosion of the surface of the silicide film 44 made of a nickel alloy by the mixed acid solution and unevenness on the surface of the silicide film 44. be able to. Therefore, if the semiconductor device manufacturing method of this embodiment is used, a silicide film made of a nickel alloy is not easily damaged during the manufacturing process, and even if it is miniaturized, junction leakage is suppressed, and high performance with good heat resistance. A simple silicide film can be formed. Therefore, in the semiconductor device manufacturing method of the present embodiment, a highly reliable semiconductor device including a silicide film made of a nickel alloy can be manufactured with a high yield.

  Furthermore, in the manufacturing method of the present embodiment, unlike the manufacturing method of the first embodiment, the second solution 46 is a complex acid protection solution in which a mixed acid solution is mixed with a salt containing a cyano group. The film 48 can be formed and the residue 47 Pt can be dissolved. As a result, the same effect as that of the manufacturing method of the first embodiment can be obtained without separately providing a step of forming a complex on the silicide film 44, so that the throughput of the semiconductor process is improved and the reliability is improved efficiently. A high semiconductor device can be manufactured.

  Hereinafter, the reason why the formation of the protective film 48 and the dissolution of the residue 47 occur simultaneously in the step shown in FIG. 4C will be described from the viewpoint of the mechanism in which Pt and Ni are dissolved.

First, in the dissolution of Pt by a mixed acid solution of nitric acid and hydrochloric acid, nitrosyl chloride (NOCl) is generated by the reaction of Formula 2.
HNO ₃ + 3HCl → NOCl + Cl ₂ + 2H ₂ O (Formula 2)

Next, the generated NOCl reacts with Pt to form chloroplatinate ions ([PtCl ₆ ] ²⁻ ), and Pt dissolves. Thereby, in the step shown in FIG. 4C, the residue 47 made of Pt is removed. Here, as in the manufacturing method of the present embodiment, when a mixed solution in which a salt (NaCN) containing a cyano group is added to the mixed acid solution is used as the second solution 46, the CN group is a cyanide ion (CN ⁻ ) And becomes an anion in the mixed solution. Since the cyanide ion having a negative charge repels the chloroplatinate ion ([PtCl ₆ ] ²⁻ ) having a negative charge, a complex is not formed.

On the other hand, Ni contained in the silicide film 44 reacts with Cl ^{− of} hydrochloric acid to become Ni ^{2+ and} dissolves. This Ni ²⁺ having a positive charge is electrically attracted to CN ⁻ having a negative charge to form a complex composed of [Ni (CN) ₄ ] ²⁻ . As a result, a protective film 48 made of H ₂ [Ni (CN) ₄ ] and Na ₂ [Ni (CN) ₄ ] is formed on the silicide film 44. Here, even if the protective film 48 is formed, Ni contained in the protective film 48 is not easily affected by Cl ⁻ . As described in the first embodiment, NiCl ₂ which is a reaction product of Ni and hydrochloric acid has an ionic bond, whereas [Ni (CN) ₄ ] ²⁻ has a covalent bond. Because. In general, a covalent bond is stronger and more stable than an ionic bond. Therefore, even when hydrochloric acid is supplied to the complex [Ni (CN) ₄ ] ^2- having a strong covalent bond, the reaction between nickel and Cl ⁻ does not easily proceed, and H ₂ [Ni (CN) ₄ ] And dissolution of nickel contained in the protective film 48 made of Na ₂ [Ni (CN) ₄ ] is suppressed.

As described above, in the step shown in FIG. 4C, when the second solution 46 is supplied, Pt is dissolved as chloroplatinate ions ([PtCl ₆ ] ²⁻ ), and silicide A protective film 48 made of H ₂ [Ni (CN) ₄ ] and Na ₂ [Ni (CN) ₄ ] is formed on the film 44.

Here, in the manufacturing method of the semiconductor device of this embodiment, a cyano group (CN ⁻ ) is used as a ligand coordinated to nickel. The cyano group has a negative charge and is the same charge for the metal (Pt) to be dissolved, while it is a different charge for the metal (Ni) to be protected. By using such a ligand, the selectivity of complex formation is enhanced, and Pt removal and Ni protection can be performed in the same step.

Further, the complex constituting the protective film 48 formed on the silicide film 44 preferably has high adsorptivity to the silicide film 44 in order to sufficiently protect the surface of the silicide film 44. Here, since the cyano group has N having a high electronegativity, it has a strong polarity between CN. In the complex [Ni (CN) ₄ ] ²⁻ having a CN group as a ligand, a cyano group is bonded to Ni in a planar shape, and thus the complex [Ni (CN) ₄ ] ²⁻ has a planar structure. Become. That is, the complex [Ni (CN) ₄ ] ²⁻ is a complex having polarity and a planar structure. As a result, when the complex [Ni (CN) ₄ ] ²⁻ is formed on the silicide film, electrostatic induction occurs on the silicide film 44 due to the polarity of the complex [Ni (CN) ₄ ] ²⁻ , and the complex [Ni (CN) ₄ ] ^2- is easily adsorbed on the silicide film. As a result, the surface of the silicide film 44 is sufficiently protected by the protective film 48 made of a complex, so that nickel contained in the silicide film 44 can be prevented from excessively reacting with Cl ⁻ or CN ⁻ .

In the manufacturing method of the present embodiment, a mixed solution in which NaCN is added to a mixed acid solution of hydrochloric acid and nitric acid is used as the second solution 46. However, the present invention is not limited to this, and at least forms a complex with nickel. Any solution containing the compound to be prepared and hydrochloric acid may be used. Thereby, the residue 47 remaining in the non-silicide region can be removed while forming the protective film 48 made of a complex on the silicide film 44. In particular, as a compound that forms a complex with nickel, a salt containing a cyano group is preferable because it forms a complex selectively with nickel as described above. As specific materials, besides sodium cyanide (NaCN), cesium cyanide (CeCN), potassium cyanide (KCN), potassium ferrocyanide (K ₄ [Fe (CN) ₆ ]), potassium ferricyanide (K ₃ [Fe] Even if (CN) ₆ ]) is used, the same effect as the manufacturing method of the present embodiment can be obtained. On the other hand, the solution for removing the remaining residue 47 (Pt) is not limited to a mixed acid solution of hydrochloric acid and nitric acid. For example, a mixed solution of hydrochloric acid and hydrogen peroxide, or simply hydrochloric acid is used. However, the same effect as the manufacturing method of this embodiment can be obtained. In addition, when using only hydrochloric acid, you may use what added water to concentrated hydrochloric acid, for example.

  In the method for manufacturing a semiconductor device of the present embodiment, a mixed solution of sulfuric acid and hydrogen peroxide is used as the first solution 45, but the present invention is not limited to this, and any solution having oxidizing properties may be used. Good. In particular, a mixed solution of any one of sulfuric acid, nitric acid, acetic acid, or phosphoric acid and hydrogen peroxide is preferable because nickel contained in the alloy film 43 remaining unreacted can be efficiently dissolved.

  Below, the effect of the manufacturing method of the semiconductor device of this embodiment is demonstrated. FIG. 5 is a diagram showing the evaluation results of the thickness of the silicide film according to the method for manufacturing the semiconductor device of the present embodiment. FIG. 6 shows the evaluation results of the resistance value of the silicide film according to the method for manufacturing the semiconductor device of this embodiment.

  FIG. 5A shows a conventional method in which a step of forming a silicide film (silicide film formation) and a step of removing an unreacted alloy film using a mixed acid solution of nitric acid and hydrochloric acid (mixed acid solution treatment) are performed. These are the results of measuring the thickness of the silicide film after each step. FIG. 5B shows a step of forming a silicide film (silicide film formation) shown in FIG. 4A and a sulfuric acid and peroxidation shown in FIG. 4B according to the method for manufacturing the semiconductor device of this embodiment. In the step of supplying a mixed solution of hydrogen (mixed solution treatment) and the step of supplying a mixed acid solution in which NaCN is mixed with the mixed acid solution of nitric acid and hydrochloric acid (mixed acid solution treatment) shown in FIG. It is the result of having measured the film thickness of each film | membrane.

As shown in FIG. 5, in the conventional method A, when the treatment is performed with a mixed acid solution of hydrochloric acid and nitric acid, the thickness of the silicide film is reduced by about 2.7 nm compared to the thickness after the silicide film is formed. This decrease in film thickness is thought to be because Ni contained in the silicide film reacted with hydrochloric acid to be dissolved as Ni ²⁺ . On the other hand, in the manufacturing method B of the present embodiment, even after the mixed acid solution treatment, the thickness of the silicide film is hardly changed compared to the thickness after the silicide film is formed. This is thought to be because, unlike the conventional method, the nickel elution phenomenon in which Ni on the surface of the silicide film reacts with hydrochloric acid to become Ni ²⁺ is suppressed.

  FIG. 6 shows the results of evaluating the variation in the sheet resistance value of the silicide film according to the method for manufacturing the semiconductor device of the present embodiment. A shown in FIG. 6 is the result of preparing a plurality of silicide films formed using a conventional method and measuring the sheet resistance values of the plurality of samples in the same manner as A shown in FIG. B shown in FIG. 6 is a result of preparing a plurality of silicide film samples formed by using the manufacturing method of the present embodiment and measuring the sheet resistance values of the plurality of samples. As shown in FIG. 6, the sheet resistance value of the sample manufactured by the conventional method A has a large variation, but the sheet resistance value of the silicide film manufactured by the manufacturing method B of this embodiment hardly varies. Specifically, the uniformity of the sheet resistance variation of the silicide film is improved by 83% in the manufacturing method B of the present embodiment compared to the conventional method A.

Here, a detailed calculation method of the uniformity X (%) of the variation will be described below. As described above, the variation uniformity X (%) is calculated by Equation 1 (see the first embodiment) using the maximum value, the minimum value, and the average value of the measured values of the sheet resistance value. Using Equation 1, determine the conventional methods uniformity of dispersion of the sheet resistance value in A X _{A (%),} the uniformity X _B of variation of the sheet resistance value in the production method B of the present embodiment _(%) of each And X _A (%) = 1/2 × (230000-20000) /85000×100=13.5 (%), X _B (%) = 1/2 × (29000−2000) / 22000 × 100 = 20 .5 (%). Therefore, the improvement rate (%) of the uniformity of the variation in the manufacturing method B of this embodiment with respect to the conventional method A is [(X _A −X _B ) / X _A ] × 100 = [(123.5-20. 5) /123.5] × 100 = 83 (%).

  In the manufacturing method B of the present embodiment, a silicide film having a lower resistance than that of the conventional method A can be obtained. From the above results, when the semiconductor device manufacturing method of the present embodiment is used, a silicide film having a relatively low resistance and good performance can be stably formed, and a highly reliable semiconductor device can be manufactured with high yield. .

  In the first embodiment and the second embodiment of the present invention, a nickel alloy containing platinum (Pt) in nickel is used as the alloy film. However, the present invention is not limited to this. For example, even when an alloy film containing a metal having a smaller ionization tendency than nickel such as palladium (Pd) is used, the same effect as the present invention can be obtained.

  The method for manufacturing a semiconductor device of the present invention is useful for improving the performance of a semiconductor device having a silicide film made of an alloy film.

(A)-(d) is sectional drawing which shows the manufacturing method of the semiconductor device of the 1st Embodiment of this invention. These are figures which show the film thickness of the silicide film | membrane which concerns on the manufacturing method of the semiconductor device of 1st Embodiment. These are figures which show the sheet resistance of the silicide film | membrane which concerns on the manufacturing method of the semiconductor device of 1st Embodiment. (A)-(c) is sectional drawing which shows the manufacturing method of the semiconductor device of the 2nd Embodiment of this invention. These are the graphs which show the evaluation result of the film thickness of the silicide film which concerns on the manufacturing method of the semiconductor device of 2nd Embodiment. These are the results showing the sheet resistance of the silicide film according to the manufacturing method of the semiconductor device of the second embodiment. (A), (b) is sectional drawing which shows the silicide process of the conventional semiconductor device.

Explanation of symbols

11 Semiconductor substrate
12 Insulating film
13 Alloy film
14 Silicide film
15 First solution
16 Third solution
17 residue
18 Second solution
19 Protective film
41 Semiconductor substrate
42 Insulating film
43 Alloy film
44 Silicide film
45 First solution
46 Second solution
47 residue
48 Protective film

Claims (13)

A step (a) of forming an alloy film containing nickel and a metal having a smaller ionization tendency than nickel on a substrate made of silicon;
(B) forming a silicide film by reacting the silicon and the alloy film by heat-treating the substrate;
After the step (b), a step (c) of supplying an oxidizing first solution to the substrate and dissolving the nickel contained in the unreacted portion of the alloy film remaining on the substrate (c) )When,
After the step (c), a second solution containing a compound that forms a complex with nickel is supplied to the substrate, and the nickel contained in the silicide film reacts with the compound to generate a complex. A step (d) of forming a protective film made of the complex on the silicide film;
And (e) dissolving the metal remaining on the substrate in a state where the silicide film is covered with the protective film by supplying a third solution containing hydrochloric acid to the substrate. A method for manufacturing a semiconductor device.   The method of manufacturing a semiconductor device according to claim 1, wherein the metal is platinum or palladium. The step (e) is performed after the step (d),
The method for manufacturing a semiconductor device according to claim 1, wherein the compound contained in the second solution is a compound having an amino group.   The method of manufacturing a semiconductor device according to claim 3, wherein the second solution has a pH in a range of 7 or more and 9 or less.   5. The semiconductor device according to claim 3, wherein the second solution is one selected from ammonia water, methylamine water, ethylamine water, hexamethylenediamine water, and tetramethylethylenediamine water. Manufacturing method.   The method for manufacturing a semiconductor device according to claim 1, wherein the compound contained in the second solution is a salt having a cyano group.   The method of manufacturing a semiconductor device according to claim 6, wherein the compound is one selected from sodium cyanide, cesium cyanide, potassium cyanide, potassium ferrocyanide, and potassium ferricyanide.   The step (d) and the step (e) are performed at the same time, and consist of a complex containing the cyano group and the nickel on the silicide film using a mixed solution of the second solution and the third solution. 8. The method of manufacturing a semiconductor device according to claim 6, wherein the protective film is formed and the metal remaining on the substrate is dissolved. The mixed solution is a solution containing the salt having the cyano group and the hydrochloric acid,
The method for manufacturing a semiconductor device according to claim 8, wherein the concentration of the salt having a cyano group is 1 ppm or more and 100 ppm or less.   The method for manufacturing a semiconductor device according to claim 1, further comprising a step (f) of removing the protective film after the step (e).   In the step (f), the substrate is cleaned using hot water of 70 ° C. or more and 90 ° C. or less, or is thermally oxidized at 150 ° C. or more and 250 ° C. or less. A method for manufacturing a semiconductor device according to claim 10.   The first solution according to any one of claims 1 to 11, wherein the first solution is a mixed solution of any one of sulfuric acid, nitric acid, acetic acid, and phosphoric acid and hydrogen peroxide. A method for manufacturing a semiconductor device.   The third solution according to any one of claims 1 to 12, wherein the third solution is a mixed solution of hydrochloric acid and nitric acid, a mixed solution of hydrochloric acid and hydrogen peroxide, or a mixed solution of concentrated hydrochloric acid and water. The manufacturing method of the semiconductor device of description.

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