JP5754702B2 - Method for searching for barrier material for semiconductor integrated circuit device and barrier material for semiconductor integrated circuit device searched by the searching method - Google Patents

Description

  According to the present invention, in a semiconductor integrated circuit device having a copper wiring layer, as a substitute for a conventional ruthenium barrier material, a novel barrier material searching method for a semiconductor integrated circuit device having an excellent copper diffusion suppressing effect and the searching method are provided. The present invention relates to a barrier material for a semiconductor integrated circuit device to be searched.

  Semiconductor integrated circuit devices (LSIs) are being integrated at a high speed, with the integration density quadrupling in three years, which is said to be Moore's Law, and the International Semiconductor Technology Roadmap (International Technology Roadmap for Taking the MPU (Micro Processing Unit) wiring of the 2009 edition (ITRS 2009 Edition) as an example, the wiring width target value is 45 nm in 2010, 32 nm in 2013, and 2015 in order to improve the degree of integration. The year is 25 nm and the year 2017 is 20 nm. In order to ensure high-speed operation, the target values of resistivity are 4.08 μΩcm, 4.83 μΩcm, 5.44 μΩcm, and 5.99 μΩcm, respectively.

  With such demands for higher integration, higher density, and higher speed of LSI, miniaturization and multilayering of wiring are progressing, and conventionally used aluminum (Al) and its wiring are also used for LSI wiring. Instead of alloys, the practical application of copper (Cu) wiring has been studied. The Cu wiring has advantages such as (1) low resistance, (2) high electromigration, and (3) high melting point, and is advantageous in miniaturization compared to Al wiring. In addition, technologies required for practical use of Cu wiring, for example, wiring forming method by plating method and flattening technology of multilayer wiring layer by mechanical polishing CMP etc. have been developed at the same time. Semiconductor devices having the above occupy an increasingly important position in the field of LSI.

  In Cu multilayer wiring of a semiconductor integrated circuit device, a low dielectric constant material (so-called low-K material) or Si-O is used for an interlayer insulating film in order to suppress signal delay as the wiring is further miniaturized. A material containing the structure is used. However, Cu, which is a wiring material, has a problem that it does not only easily diffuse in the insulating films made of these materials, but also has poor adhesion to these insulating films. Therefore, in general, a barrier metal film such as Ta, Ti, TaN, TiN or the like is formed as the base of the Cu wiring to prevent Cu diffusion and improve the adhesion between the Cu wiring and the insulating film. ing. These metals and metal alloys are effective in solving such problems. However, since the resistance is higher than that of Cu, the resistance of the barrier film is also reduced in order to achieve higher speed operation of LSI. Is strongly demanded. Also, since the conventional barrier film has a high resistance, when a Cu wiring is formed by plating or the like, a seed film such as a low resistance Cu or Cu-Al alloy is newly provided on the barrier film. Therefore, it is necessary to form a composite film composed of a barrier film and a seed film, and the manufacturing process of the semiconductor integrated circuit device is complicated.

In order to solve such a problem, formation of a barrier metal film using a low-resistance metal has been studied. For example, Patent Documents 1 to 5 propose ruthenium barrier films. Ruthenium has specific resistance values of 9 × 10 ⁻⁶ Ω · cm and 7 × 10 ⁻⁶ Ω · cm in amorphous and polycrystalline, respectively, and 15 × 10 ⁻⁶ Ω · cm of conventional Ta and Ti. This is because it is lower than 80 × 10 ⁻⁶ Ω · cm, and even when applied as a barrier film of a Cu wiring layer, a certain degree of suppression effect on Cu diffusion can be obtained. In addition, since the ruthenium barrier film has a low resistance, a copper wiring can be formed directly on the barrier layer by a direct plating method or the like without providing a seed layer. Patent Documents 1 to 5 disclose a sputtering method, a chemical vapor deposition (CVD) method, an atomic layer deposition (ALD) method, a plating method, or the like as a method for forming a ruthenium barrier film.

  However, since ruthenium described in Patent Documents 1 to 5 described above as a barrier material is a rare metal, there is a problem that the cost is high even in the present situation and it may not be used in the future.

  On the other hand, in Patent Document 6, in order to suppress the diffusion of copper constituting the wiring layer, focusing on the short side and the long side length of the unit crystal lattice of ruthenium and copper, the difference and ratio thereof are defined. It has been proposed to do. Further, it is described that rhodium, iridium, osmium or platinum having a crystal lattice similar to ruthenium can be used as the barrier material for the short side and the long side of the unit crystal lattice.

JP 2009-206322 A JP 2009-117633 A JP 2010-177538 A Special table 2010-536159 gazette JP 2002-75994 A JP 2004-48066 A

  However, rhodium, iridium, osmium, or platinum described in Patent Document 6 is a rare metal or a very expensive metal, and like ruthenium, the cost is high even at present and cannot be used in the future. There is. Therefore, in a semiconductor integrated circuit device having a Cu wiring layer, development of a new barrier material having no problem in terms of supply and having a relatively low cost while having an effect equivalent to or better than that of ruthenium for suppressing the diffusion of Cu. It has been demanded.

  In addition, the search for a new barrier material is generally performed by a conventional method in which a number of various metals or intermetallic compounds are searched by trial and error by trial production or experimentation, but this method is efficient. It is not a thing and requires a great deal of cost and time. In Patent Document 6 described above, in order to search for a barrier material that suppresses diffusion of Cu as a wiring layer, attention is paid to the lengths of the short side and the long side of the unit crystal lattice of ruthenium and Cu, and the difference therebetween. In addition to ruthenium, rhodium, iridium, osmium or platinum, there is no problem in terms of supply, and a cheaper metal or an intermetallic compound containing the metal is used as a barrier material. It has not yet reached the knowledge that it can be applied. Therefore, a new method for efficiently searching for a new barrier material to replace ruthenium in a shorter time needs to be studied.

  The present invention has been made in view of the above-described conventional problems, and has an effect equal to or higher than that of a conventional ruthenium barrier material for suppressing copper diffusion, has no problem in terms of supply, and is relatively Provided is a method for searching a barrier material for a semiconductor integrated circuit device comprising a low-cost metal or an intermetallic compound containing the metal, and a novel barrier material for a semiconductor integrated circuit device comprising a metal or a metal compound selected by the searching method. There is.

  The present invention relates to a combination of ruthenium, which has been conventionally used as a barrier material, and copper, which is a wiring layer metal, so that each crystal lattice and physical property value maximizes the copper diffusion suppression. As a result of diligently examining whether or not they are related, a barrier material having excellent copper barrier properties can be obtained by finding a new method for searching for a substitute for ruthenium that can significantly reduce the diffusion of copper as a wiring layer metal. As a result, the present invention has been achieved.

That is, the configuration of the present invention is as follows.
(1) A crystal structure of a face-centered cubic lattice or a hexagonal close-packed lattice as a barrier material constituting the barrier film of a semiconductor integrated circuit device having a copper wiring layer on a barrier film or a composite film composed of a barrier film and a seed film respect has, nearest interatomic distance in packed planes of the unit crystal lattice _{(D M)} is nearest interatomic distance in packed planes of the unit crystal lattice of ruthenium _{(D Ru),} -0.125 angstrom (Å ) ≦ (D _M −D _Ru ) ≦ 0.0641 angstrom (Å) and a metal other than ruthenium or an intermetallic compound having a melting point or transformation point of 853-1873 Kelvin (K) is selected. Provided is a method for searching a barrier material for an integrated circuit.
(2) The closest interatomic distance (D _M ) on the dense surface of the unit crystal lattice of the barrier material constituting the barrier film is further equal to the closest interatomic distance (D _Cu ) on the dense surface of the copper unit crystal lattice. In contrast, the barrier material for a semiconductor integrated circuit according to the above (1) satisfying the relationship of | [(D _M −D _Cu ) / D _Cu ] | × 100> 3.0 as an absolute value Provide a search method.
(3) The method for searching a barrier material for a semiconductor integrated circuit as described in (2) above, wherein the barrier material constituting the barrier film has a melting point or transformation point of 1000 to 1873 Kelvin (K).
(4) gold Shokumata to be searched by a method according to any one of (1) to (3) is to provide a semiconductor integrated circuit device for a barrier material made of intermetallic compound.
(5) The metal or intermetallic compound is any one selected from the group consisting of IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, Pd ₃ Fe, NiPt, FePd, and Ni ₃ Pt. The barrier material for a semiconductor integrated circuit device according to (4) above is provided.
(6) The metal or intermetallic compound is any one selected from the group consisting of IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, Pd ₃ Fe, NiPt, and FeP d The barrier material for a semiconductor integrated circuit device according to (4) is provided.
(7) The metal or intermetallic compound is any one selected from the group consisting of IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, and Pd ₃ Fe (4) The barrier material for semiconductor integrated circuit devices described in 1. is provided.
(8) The barrier material for a semiconductor integrated circuit device according to (4) , wherein the metal or intermetallic compound is IrMo.

  According to the search method of the present invention, it is not necessary to search for a large number of various metals or intermetallic compounds by trial and error by trial production or experiment, and after narrowing candidate materials by simulation, the characteristics are confirmed and the optimum material is selected. Can be selected. Therefore, it becomes possible to search for a ruthenium substitute barrier material having an excellent barrier property against copper diffusion suppression efficiently and in a short time.

According to the present invention, since the closest interatomic distance (D _M ) of the unit crystal lattice of the material constituting the barrier film is in a region close to the closest interatomic distance (D _Ru ) of the ruthenium unit crystal lattice, As with ruthenium, which has been used as a material for barrier films, a ruthenium alternative barrier material for semiconductor integrated circuits that can be expected to have an excellent effect on copper diffusion suppression and has no problem in terms of supply performance is obtained. be able to. Further, the barrier material according to the present invention has a resistance value higher than that of conventional barrier materials such as Ta, Ti, TaN, and TiN because the distance between nearest atoms (D _M ) of the unit crystal lattice is close to that of ruthenium having a low resistance. Therefore, it can be used as a barrier material for a semiconductor integrated circuit device that is required to have high integration, high density, and high speed in the future. In addition, the barrier material according to the present invention not only has a unit crystal lattice close to a ruthenium single crystal lattice having a high cohesive energy, but also has a melting point or transformation temperature generally adopted as a temperature for crystallization annealing of copper wiring 250. Since it is higher than ˜400 ° C. (523 to 673 Kelvin (K)), it has an effect of sufficiently suppressing copper diffusion without melting or deformation during the manufacturing process.

It is a schematic sectional drawing of the semiconductor integrated circuit device which formed the copper wiring layer on the barrier film. It is a schematic sectional drawing of the semiconductor integrated circuit device which formed the copper wiring layer on the composite film which consists of a barrier film and a seed film. It is a figure which shows the relationship between the distance between nearest atoms of various barrier materials of this invention, and melting | fusing point or transformation temperature. It is a figure which shows the area | region of A and B in the relationship between the distance between nearest atoms of various barrier materials of this invention, and melting | fusing point or transformation temperature. It is an enlarged view which shows the area | region of C in the relationship between the distance between nearest atoms of various barrier materials of this invention, and melting | fusing point or transformation temperature.

  FIG. 1 is a schematic cross-sectional view of a semiconductor integrated circuit device in which a copper wiring layer is formed on a barrier film, and an actual semiconductor integrated circuit device has eight, nine, or more wiring layers. In order to simplify the above, a two-layer wiring structure is illustrated. In the figure, 1 is a semiconductor substrate on which a large number of circuit elements (not shown) are formed adjacent to one main surface 1a, and 2 is, for example, a silicon oxide formed on one main surface 1a of the semiconductor substrate 1. A first insulating layer made of a material layer, 2a is a through hole formed in the first insulating layer 2, 3 is a plug made of, for example, tungsten formed in the through hole 2a, and 3a is between the through hole 2a and the plug 3. A barrier film 4 is formed on the first insulating layer 2 and the plug 3 via a silicon nitride layer 41, for example, and is formed of a second insulating layer made of, for example, a silicon oxide layer 42. 4a is a second insulating layer 4 The first trench 5 formed in the first trench 5 is a first copper wiring formed in the first trench 4a, 5a is a barrier film formed between the first trench 4a and the first copper wiring 5, 6 is the second On the insulating layer 4 and the first copper wiring 5 For example, a third insulating layer formed by sequentially laminating, for example, a silicon oxide layer 62, a silicon nitride layer 63, and a silicon oxide layer 64 with a silicon nitride layer 61 interposed therebetween, and 6a is a cross section T formed on the second insulating layer 6. A second trench having a letter shape, 7 is a second copper wiring formed in the second trench 6 a, and 7 a is a barrier film formed between the second trench 6 a and the second copper wiring 7. The first copper wiring 5 and / or the second copper wiring 7 is usually annealed at a temperature of 250 to 400 ° C. (523 to 673 Kelvin (K)) to adjust the crystal state of the copper wiring.

  In FIG. 2, seed films 5 b and 7 b made of, for example, low resistance copper or copper-aluminum alloy are provided on the barrier films 5 a and 7 a to form a composite film made of a barrier film and a seed film. This is a semiconductor integrated circuit in which a copper wiring layer is formed by plating or the like. The seed films 5b and 7b are used for performing copper plating when the barrier film has high resistance.

In order to apply the present invention to at least one of the barrier layers 3a, 5a, and 7a shown in FIGS. 1 and 2, a novel barrier film material is selected as an alternative to the conventionally used ruthenium barrier film. This search method is based on the following search guidelines.
<1> The crystal structure has a close-packed surface close to a ruthenium film,
<2> Increasing the cohesive energy, that is, the melting point or the transformation temperature as close as possible to the ruthenium film,
<3> The crystal lattice is close to the Cu lattice, and the mismatch rate with the Cu lattice is appropriate.

  <1> to <3> above are models of the laminated state of a copper (Cu) film with respect to a ruthenium (Ru) film and a silicon (Si) film and a titanium (Ti) film that have been conventionally used as a barrier film. This is the knowledge obtained from the result of calculation simulation of the diffusion state of Cu into the Ru film by the molecular dynamics method. Here, the crystal orientation planes of the Ru film, Si film, and Ti film were calculated as (100) and (0001), and the crystal orientation plane of the Cu film was calculated as (111). The molecular dynamics method (MD) used as a calculation method is a calculation method that considers a material as an aggregate of atoms / molecules and tracks the movement of individual atoms / molecules to clarify the correlation between the atomic structure and material properties. Yes, it is the best tool for virtual experiments for nanoscale material control and development. MD calculation is a repetition of time integration calculation and interaction calculation. In other words, the force received by the atom is calculated from the interatomic potential, and the position and velocity of the atom are obtained by integrating the Newton equation of motion for a very short time. By repeating this series of flows, it is possible to calculate how the atoms constituting the material change with time.

  From the simulation results of each model of Cu—Ru, Cu—Si, and Cu—Ti, it was found that the Ru film tends to suppress Cu diffusion more than the Si film or Ti film. The degree of Cu diffusion suppression is not determined only by the crystal structure of the barrier film, but at least a metal or an intermetallic compound having a crystal structure close to Ru can be applied as a barrier material having a Cu diffusion suppression effect. Conceivable. It is known that the diffusion of Cu is more effectively suppressed as the barrier material has a smaller difference in length between the sides of Cu and the unit crystal lattice (see paragraph [0005] of Patent Document 6). In the present invention, for a compound having a face-centered cubic lattice (fcc) or hexagonal close-packed lattice (hcp) crystal structure having a surface structure similar to Ru, the closest interatomic distance is Cu in each unit crystal lattice. We focused on the physical quantity that has the most influence on the barrier property against diffusion. This closest interatomic distance is a physical quantity determined by an X-ray crystal structure analysis (X-ray diffraction) method, and is described in, for example, a metal data book (2nd edition, edited by the Japan Institute of Metals, pp. 49-50). It can be obtained by examining the lattice constant of the compound and calculating from the value and crystal structure. As described above, the closest interatomic distance defined in the present invention focuses on the Ru crystal lattice, and the present invention is not directly related to the side of the Cu crystal lattice. This is different from the invention described in Document 6.

In view of the above, the present invention provides a unit of ruthenium in which the closest interatomic distance (D _M ) of the unit crystal lattice of the material constituting the barrier film is a guideline for the above <1> to search for an alternative material for the Ru barrier film. Those in the region close to the nearest interatomic distance (D _Ru ) of the crystal lattice are selected. Here, the D _Ru is 2.7059 mm.

  Further, as one of the factors that suppress the diffusion of Cu, as shown in paragraph [0024] of Patent Document 4, it is known that the melting point of the barrier film is increased. Therefore, in the present invention, attention is paid to the melting point of the barrier film. However, when selecting a material having the closest interatomic distance to the Ru film, if the candidate material is limited to a metal composed of a single element, the selection range of the material Is to narrow. For this reason, intermetallic compounds (including alloys) that do not exhibit a single melting point are searched for by defining the thermophysical properties of the Ru substitute material according to the transformation temperature. Here, the transformation temperature is a temperature at which a phase change occurs. When the transformation occurs over a temperature range, it means a temperature at which transformation starts and ends. Further, in the present invention, if the search for materials is limited to only metals or intermetallic compounds whose melting point or transformation temperature is higher than Ru, the range of selection of materials becomes extremely narrow. For this reason, the present invention uses the <2> cohesive energy, that is, the melting point or the transformation temperature as high as possible to bring it closer to the ruthenium film as a search guideline. The melting point or transformation temperature is usually measured from the temperature change of the linear expansion coefficient or the endothermic or suggestive temperature change of the suggested scanning calorimeter (DSC). For example, the metal data book (2nd edition, The Japan Institute of Metals) Pp. 523-555), the present invention uses data obtained therefrom.

  In the present invention, the material of the barrier film instead of the Ru film needs to have a melting point or transformation temperature of 650 Kelvin (K). If it is higher than this temperature, it is higher than 250 to 400 ° C. (523 to 673 Kelvin (K)), which is generally adopted as the crystallization annealing temperature of the copper wiring, so that it does not greatly affect the diffusion of Cu. . Furthermore, if the melting point or transformation temperature is 1000 Kelvin (K), the effect of suppressing the diffusion of Cu is enhanced. However, even if the melting point or transformation temperature exceeds 2000 Kelvin (K), the effect of suppressing the diffusion of Cu is not significantly improved. preferable. For example, when the barrier film is formed by a sputtering method, the upper limit value of the melting point or transformation temperature is set to 2000 Kelvin (K) because the sputtering temperature can be made lower than before or the power consumption can be reduced. It is preferable.

In the present invention, in addition to the above guidelines <1> to <2>, a metal having a crystal lattice close to the Cu lattice and having a suitable mismatch rate with the Cu lattice, as indicated by the above guide <3> It is more preferable to search for intermetallic compounds. As described in Patent Document 6 described above, it is known that a material having a small difference in side length of the unit crystal lattice between Cu and the barrier film has a higher effect of suppressing the diffusion of Cu. . However, the effect of suppressing Cu nucleation does not increase as the mismatch rate of the closest interatomic distance with the Cu crystal is reduced. For example, nickel (Ni) having a mismatch rate of -2.56% with the lattice constant of Cu is very good in lattice matching, but is likely to cause mutual diffusion and forms a solid solution with a total rate. Accordingly, Cu as a wiring metal easily diffuses to the substrate, and it is inappropriate to use Ni as a barrier film. Based on this finding, the present invention is based on the fact that the closest interatomic distance (D _M ) of the unit crystal lattice of the material constituting the barrier film is smaller than the closest interatomic distance (D _Cu ) of the copper unit crystal lattice. It is necessary to search for a metal or an intermetallic compound that satisfies the relationship of | [(D _M −D _Cu ) / D _Cu ] | × 100> 3.0 as an absolute value. That is, a material in which the mismatch rate of the distance between the closest atoms of the barrier film and the Cu film exceeds 3% in absolute value can improve the barrier property against Cu diffusion. Here, the D _Cu is 2.5562%. The present invention is based on such a technical idea, and is obtained by adding a new technical idea to the invention described in Patent Document 6.

  Next, the present invention will be described by specific embodiments.

<First Embodiment>
FIG. 3 shows the relationship between the closest interatomic distance (Å) at the thin film interface between the film formed from the material constituting the barrier film and the Cu film and the melting point or transformation temperature of the material constituting the barrier film. . FIG. 3 shows the closest interatomic distance (Å) and the melting point or transformation temperature of Ru, Si and Ti conventionally used as barrier film materials. Other plots are metals or intermetallic compounds with a clear crystal structure and a clear interatomic distance and melting point or transformation temperature of the unit crystal lattice. In FIG. 3, the closest interatomic distance (D _M ) is close to the closest interatomic distance (D _Ru ) of the ruthenium unit crystal lattice, specifically, −0.125Å ≦ (D _M −D _Ru ) ≦ 0.0641 Å , and the melting point or transformation point range of 853-1873 Kelvin (K) is surrounded by a solid line as the region A. The closest interatomic distance surrounded by the region A is specifically in the range of 2.5809 to 2.7700 mm .

4 and 5 are enlarged views of FIG. The range surrounded by the dotted line as the region B shown in FIG. 4 is such that the closest interatomic distance (D _M ) of the unit crystal lattice is more than the closest interatomic distance (D _Cu ) of the copper unit crystal lattice. It is a metal or an intermetallic compound that satisfies the relationship of | [(D _M −D _Cu ) / D _Cu ] | × 100> 3.0 as an absolute value. The closest interatomic distance surrounded by B is specifically in the range of 2.6328 to 2.7700 mm . Further, the range surrounded by the one-dot chain line as the region C shown in FIG. 5 has a melting point or transformation point of 1000 to 1873 Kelvin (K) .

Table 1 shows the metals or intermetallic compounds (1) to (12) included in the ranges A, B, and C shown in FIGS. 4 and 5. Table 1, Ru conventionally used as a barrier film material, Si, nearest interatomic distance between Ti及beauty C u and (Å) are shown together melting or transformation temperature. Moreover, in Table 1, the metal or intermetallic compound contained in each area | region of A, B, or C is shown by (circle), and what is not contained in those area | regions is shown by x.

From FIG. 1, FIG. 2, FIG. 3 and Table 1, the metals or intermetallic compounds contained in region A are IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, Pd ₃ Fe, NiPt, FePd, and Ni it is a ₃ P t. The metal or intermetallic compound contained in the region B is IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, Pd ₃ Fe, NiPt, and FeP d . Furthermore, the metal or intermetallic compound contained in the region C is IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, and Pd ₃ Fe. As described above, according to the barrier material searching method of the present invention, it is not necessary to repeat trial and error by trial production or experiment, and a new barrier candidate material that can replace the ruthenium barrier film can be easily searched.

  Next, a simple evaluation was performed as to how much the metal or intermetallic compound shown in Table 1 shows the suppression of diffusion of Cu as a barrier material.

<Embodiment 2>
No. in Table 1 Sputtering was performed on a silicon substrate having an SiO ₂ film having a thickness of 200 nm on the surface, using an alloy ingot made of an IrMo intermetallic compound shown in FIG. The sputtering process was performed for 5 minutes at a direct current power of 200 W under a reduced pressure of 4 × 10 ⁻⁹ Torr, using argon as a sputtering gas and setting the temperature of the silicon substrate to 200 ° C., for example. Thereafter, hydrogen annealing was performed at 300 ° C. for 5 minutes. The thickness of the produced IrMo barrier film was 25 nm. In addition, in order to compare the Cu diffusion suppression effect with the Ru barrier film, a Ru film having a thickness of 25 nm was prepared by performing a sputtering process on a silicon substrate having the same structure as described above.

  Next, a Cu film (thickness 22 nm) was formed on each of the IrMo film and the Ru film by electroplating to prepare a sample for evaluating Cu diffusion. Electroplating was performed using a plating solution consisting of copper sulfate and sulfuric acid.

  The sample of the IrMo film and the Ru film after Cu plating thus obtained was subjected to 1000 temperature cycle tests with a cycle of -40 ° C / 30 minutes and 125 ° C / 30 minutes, and 150 ° C for 1000 hours. The test of leaving at a high temperature or 1000 hours under a high temperature and high humidity at 85 ° C. and 85% was conducted. After the test, a cross-section of the sample was observed, and the Cu element was subjected to surface analysis measurement (SEM-EDX measurement) of the Cu element using a scanning electron microscope (SEM). As a result, in the IrMo film, no Cu element was observed near the interface of the silicon substrate under any conditions. Also, almost no Cu intrusion into the IrMo film was observed at the boundary with the Cu film, and it was confirmed that the Cu diffusion suppressing effect was high. On the other hand, as a result of performing the same SEM-EDX measurement on the Ru film, similarly, no penetration of Cu into the Ru film was observed at the boundary with the Cu film. As described above, it was confirmed that the IrMo film has a Cu diffusion suppressing effect close to that of the Ru film under the above-described various conditions employed when evaluating the reliability of the semiconductor integrated circuit device. Whether the IrMo film has a higher Cu diffusion suppressing effect than the Ru film has not been grasped at present.

<Embodiment 3>
No. in Table 1 Sputtering was performed on a silicon substrate having an SiO ₂ film having a thickness of 200 nm on the surface, using a NiPt intermetallic compound shown in FIG. For example, the sputtering treatment was performed with 200 W DC power under a reduced pressure of 4 × 10 ⁻⁹ Torr, using argon as a sputtering gas, and setting the temperature of the silicon substrate to 200 ° C. The sputtering time was adjusted so that the NiPt film thickness after fabrication was 25 nm. Thereafter, hydrogen annealing was performed at 300 ° C. for 5 minutes.

  Next, a Cu film (thickness 22 nm) was formed on the NiPt film by electroplating in the same manner as in the first embodiment to prepare a sample for evaluating Cu diffusion.

  A sample of the NiPt film after Cu plating obtained in this way was subjected to 1000 temperature cycle tests with a cycle of -40 ° C./30 minutes and 125 ° C./30 minutes left as in the first embodiment. , 150 ° C. for 1000 hours, or 85 ° C. for 85 hours at 85% high temperature and humidity. After the test, the cross section of the sample was observed, and the Cu element was subjected to surface analysis measurement (SEM-EDX measurement) of Cu element using SEM. As a result, in the NiPt film, no Cu element was observed near the interface of the silicon substrate under any conditions. On the other hand, a slight intrusion of Cu into the NiPt film was observed at the boundary with the Cu film, and the Cu diffusion suppression effect tended to be slightly lower than that of the IrMo film of the first embodiment. .

<Embodiment 4>
No. in Table 1 Sputtering was performed on a silicon substrate having a SiO ₂ film having a thickness of 200 nm on the surface, using an alloy ingot made of an intermetallic compound of Ni ₃ Pt shown in FIG. For example, the sputtering treatment was performed with 200 W DC power under a reduced pressure of 4 × 10 ⁻⁹ Torr, using argon as a sputtering gas, and setting the temperature of the silicon substrate to 200 ° C. The sputtering time was adjusted so that the thickness of the Ni ₃ Pt film after fabrication was 25 nm. Thereafter, hydrogen annealing was performed at 300 ° C. for 5 minutes.

Next, a Cu film (thickness: 22 nm) was formed on the Ni ₃ Pt film by electroplating by the same method as in the first embodiment to prepare a sample for evaluating Cu diffusion.

A sample of the Ni ₃ Pt film after Cu plating thus obtained was subjected to a temperature cycle test in which, as in the first embodiment, a cycle of -40 ° C./30 minutes and 125 ° C./30 minutes was set as one cycle. The test was conducted 1000 times, left at a high temperature of 150 ° C. for 1000 hours, or left at 85 ° C. for 85 hours at 85% high temperature and high humidity. After the test, the cross section of the sample was observed, and the Cu element was subjected to surface analysis measurement (SEM-EDX measurement) of Cu element using SEM. As a result, in the Ni ₃ Pt film, no Cu element was observed near the interface of the silicon substrate under any conditions. However, Cu intrusion into the NiPt film was observed deeper toward the silicon substrate, and the Cu diffusion suppression effect tended to be slightly lower than that of the NiPt film of the second embodiment.

  As described above, the barrier material selected by the search method of the present invention can be expected to have a Cu diffusion suppressing effect close to that of the Ru barrier film. In addition, the barrier material of the present invention is not limited to Ru, and may be replaced with rhodium, iridium, osmium, platinum, or the like, which may be restricted in the future, or the amount of use thereof may be reduced. Therefore, it is extremely useful as a barrier film for a semiconductor integrated circuit device. Furthermore, since the barrier material of the present invention is likely to be used not only as a memory semiconductor device such as a DRAM but also as a barrier film for a low-cost semiconductor device such as a logic semiconductor device, a low-cost barrier material is provided. A wide range of uses can be expected.

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... 1st insulating layer, 3 ... Plug, 4 ... 2nd insulating layer, 4a ... 1st trench, 41 ... Silicon nitride layer, 42 ... Silicon oxide layer, 5 ... 1st copper wiring, 5a ... barrier film, 5b ... seed film, 6 ... third insulating layer, 6a ... trench layer, 61 ... silicon nitride layer, 62 ... silicon oxide layer, 63 ... silicon nitride layer, 64 ... silicon oxide layer, 7 ... first 2 copper wirings, 7a ... barrier film, 7b ... seed film.

Claims (8)

As a barrier material constituting the barrier film of a semiconductor integrated circuit device having a copper wiring layer on a barrier film or a composite film composed of a barrier film and a seed film, it has a crystal structure of a face-centered cubic lattice or a hexagonal close-packed lattice. , The closest interatomic distance (D _M ) in the dense plane of the unit crystal lattice is −0.125 angstrom (≦) ≦ ( ) with respect to the closest interatomic distance (D _Ru ) in the dense plane of the unit crystal lattice of ruthenium. D _M −D _Ru ) ≦ 0.0641 angstrom (Å) and a metal or intermetallic compound other than ruthenium having a melting point or transformation point of 853-1873 Kelvin (K) is selected. Barrier material search method. The closest interatomic distance (D _M ) in the dense surface of the unit crystal lattice of the barrier material constituting the barrier film is further compared to the closest interatomic distance (D _Cu ) in the dense surface of the copper unit crystal lattice. 2. The method for searching for a barrier material for a semiconductor integrated circuit according to claim 1 , wherein a relationship of | [(D _M −D _Cu ) / D _Cu ] | × 100> 3.0 is satisfied as an absolute value. The method for searching for a barrier material for a semiconductor integrated circuit according to claim 2 , wherein the melting point or transformation point of the barrier material constituting the barrier film is 1000 to 1873 Kelvin (K). Gold Shokumata to be searched by a method according to any one of claims 1 to 3 is composed of the intermetallic compound semiconductor integrated circuit device for a barrier material. The metal or intermetallic compound is any one selected from the group consisting of IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, Pd ₃ Fe, NiPt, FePd, and Ni ₃ Pt. The barrier material for a semiconductor integrated circuit device according to claim 4 . The metal or intermetallic compound is any one selected from the group consisting of IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, Pd ₃ Fe, NiPt, and FeP d. 5. The barrier material for a semiconductor integrated circuit device according to 4 . 5. The semiconductor according to claim 4 , wherein the metal or intermetallic compound is any one selected from the group consisting of IrMo, FePt, Mn ₃ Pt, Pt ₃ Mn, CoPt, and Pd ₃ Fe. Barrier material for integrated circuit devices. 5. The barrier material for a semiconductor integrated circuit device according to claim 4 , wherein the metal or intermetallic compound is IrMo.

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