JP2006073569A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the occurrence of resist poisoning due to unstable N flowing out of an SiCN film in a semiconductor apparatus having the SiCN film on an interconnection. <P>SOLUTION: In the manufacturing method of the semiconductor apparatus containing the SiCN film, a ratio of the flow rate of a material gas which contains an organic group in part to that of He is set to 1:4.2 or above at the time of formation of the SiCN film. Alternatively, the ratio of the flow rate of the material gas × the number of bonds of the material gas with the organic group to that of He is set to 1:1.4 or above. Consequently, an increase of SiNH groups in the SiCN film can be suppressed. In addition to that, a change in film stress and poisoning defects can also be suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to a wiring formation technique having a SiCN film.

  In a semiconductor device using a processing dimension of 0.25 μm or more, since the wiring interval has become narrower, the electric parasitic capacitance generated between the wirings has increased. The decrease in the current speed due to the increase in the electric parasitic capacitance, that is, the delay time due to the RC delay has become a value that cannot be ignored compared to the time required for turning on and off the transistor. For this reason, it is necessary to reduce the electric parasitic capacitance between the wirings in order to achieve miniaturization.

  In order to reduce the electric parasitic capacitance between the wirings, it is necessary to reduce the dielectric constant of the insulating film between the wirings in the same layer or between different wiring layers. From the 0.13 μm device, the wiring resistance value is reduced by changing the wiring metal from Al to Cu. Here, since Cu has the property of diffusing in the insulating film by thermal diffusion and electric field diffusion, it is necessary to cover the Cu wiring with a barrier film to prevent the diffusion of Cu in order to prevent the occurrence of leakage between wirings. is there. As a method for forming Cu wiring, a damascene process is generally used. Usually, a conductive barrier metal such as TaN or Ta is covered on the side wall and bottom of the Cu wiring, and the upper surface of the wiring layer is extremely low in conductivity. An insulating film made of SiN has been used as a barrier film.

  However, since the dielectric constant of the SiN film is relatively high as 7.0, the dielectric constant of the barrier film on the upper surface of the wiring layer is lowered after the next generation 0.09 μm device. Introduction of SiC films having a relative dielectric constant of about 4.5 to 5.0 and SiCN films is in progress.

  FIG. 6 shows a conventional method for manufacturing a semiconductor device, which has been studied as a multilayer wiring structure after a 0.09 μm device.

  First, as shown in FIG. 6A, a barrier metal 2 made of TaN and a depth made of Cu are formed in a first low dielectric constant film 1 having a thickness of, for example, 600 nm formed on a silicon substrate (not shown). A trench wiring 3 having a length of, for example, 300 nm is formed. A first SiCN film 4 having a film thickness of about 50 nm is formed on the upper surface of the trench wiring 3 in order to prevent Cu in the trench wiring 3 from diffusing into the second low dielectric constant film 5. On the first SiCN film 4, a second low dielectric constant film 5 having a thickness of, for example, 600 nm is formed in which an upper layer wiring and a via hole are formed. Here, for example, a C-containing silicon oxide film (SiOC film) is used for the first low dielectric constant film 1 and the second low dielectric constant film 5. Further, when a via hole pattern is formed in the second low dielectric constant film 5, an antireflection film 6 made of an organic material is used in order to prevent a pattern formation failure due to reflected light from the underlying wiring during photolithography. Is applied. Thereafter, a via hole pattern is formed in the second low dielectric constant film 5 using the photoresist 7 as a mask.

Subsequently, as shown in FIG. 6B, for example, the first SiCN is applied to the second low dielectric constant film 5 by using plasma formed by a mixed gas containing CF ₄ , Ar, and N _2. Dry etching is performed up to the top of the film 4 to open a via hole 8. The reason why the dry etching is stopped with the first SiCN film 4 is to prevent damage to the Cu film surface in the ashing for removing the resist and the polymer removing cleaning performed thereafter. At this time, low-pressure O ₂ plasma or ammonia plasma is used as the ashing gas. In the step of removing the polymer, a solution containing an amine is generally used. Such a process is designed so as not to damage as much as possible the organic group (for example, CH ₃ ) bonded to Si contained in the low dielectric constant film 5 and the SiCN film 4 having an organic group. . However, for example, N ₂ or H ₂ O in the air is taken into the SiCN film, and the stress of the film changes. Alternatively, the nitrogen component (N) added to the SiCN film when dry etching the upper second low dielectric constant film, or the nitrogen component (N) when NH ₃ ashing is performed on the exposed surface of the SiCN film after dry etching Similarly, when the exposed surface of the SiCN film after dry etching is washed with an amine-based polymer removal solution, the nitrogen component (N) contained in the removal solution may be occluded in the SiCN film.

  Here, FIG. 7 shows a time-dependent change in stress of the conventional SiCN film. It can be seen that the stress value changes only by depositing a SiCN film having a film thickness of, for example, 200 nm on a Si substrate and leaving it in a clean room. This phenomenon has already been reported by Goto et al. (Proceedings of IITC, 2003, p. 6). In such a film where the stress of the film is not stable, the stress applied to the Cu wiring is likely to change, and there is a possibility that a stress migration failure occurs in the reliability test or the film is peeled off during the wafer process.

  Further, the nitrogen component (N) in the SiCN film has the following problems.

The SiCN film uses NH ₃ or the like as one of the constituent gases of the raw material gas at the time of film formation and adds N in order to reduce the leakage current of the SiC film used previously. Therefore, the nitrogen component (N) is contained in the SiCN film 4. At this time, when unstable N is contained in the SiCN film 4, it is formed on the second organic antireflection film 10 when forming the pattern of the second layer wiring as shown in FIG. In addition, when the second photoresist 11 is resolved, it is known that a defect called a resist remnant called poisoning 12 occurs in the upper portion of the via hole (M. Fayole et al., Proceedings of Advanced Metallization Conference, 2001). , P.509). This is because the unstable nitrogen component (N) which is not strongly bonded and contained in the SiCN film becomes a base in the exposure process (indicated by NH in the figure. It is also said that an amine is generated). This is considered to enter the photoresist through the via hole, neutralize the acid generated by the exposure in the resist, and weaken the chemical amplification effect when forming the resist pattern.

  When the poisoning 12 as described above occurs, the insulating film (second low dielectric constant film 5) around the via hole may be etched into a desired shape in the next wiring trench etching process (FIG. 6D). As a result, an insulating film remains between the wiring trench 13 and the via hole 8 (FIG. 6E). Alternatively, the resist pattern may be resolved finer than a desired value, and the wiring width may be narrowed.

  Thereafter, the entire surface is etched back without forming a mask, and the SiCN film 4 having a thickness of about 50 nm at the bottom of the via hole is etched to expose the surface of the trench wiring 3 (FIG. 6F).

  Next, by combining the sputtering method and the plating method, the second barrier metal (TaN) 14 and the second wiring (Cu) 15 are embedded in the via hole 8 and the wiring groove 13 (FIG. 6G).

  Thereafter, Cu-CMP and TaN-CMP are performed, and the second wiring (Cu) 15 and the second barrier metal (TaN) 14 other than the wiring trench 13 and the via hole 8 are removed. Thereafter, a second SiCN film 17 is deposited on the upper surface of the second wiring 15 by about 50 nm (FIG. 6H).

The above manufacturing process (FIGS. 6A to 6H) was repeated to form a semiconductor device composed of a Cu multilayer wiring having a SiCN film as a part of the wiring material.
JP 2004-79761 A

  In a semiconductor device comprising a Cu multilayer wiring having a SiCN film formed by a conventional method in which a via hole is formed before a wiring groove, as described in [Prior Art], the process shown in FIG. The unstable nitrogen component (N) remaining in the SiCN film is released, and poisoning 12 that is a resist development defect may occur. In this case, as shown in FIG. 6H, there is a problem that an insulating film residue 18 in the wiring groove is generated around the via hole, and the via hole 8 and the wiring groove 13 cannot be electrically connected. In addition, there are problems such that the resist pattern is resolved finer than a desired value, the width of the wiring is narrowed, and disconnection occurs.

In order to solve the above-described problem, in the present invention, the flow rate ratio of the raw material gas having an organic group in a part of the silane structure and the inert gas He is set to 1: 4.2 or more when forming the SiCN film. Alternatively, the flow ratio of the raw material gas and the number of bonds of the organic group of the raw material gas and the flow rate ratio of He, which is an inert gas, are 1: 1.4 or more. As a result, the Si bond that easily binds to the air component out of the Si—CH ₃ and Si—H bonds in the SiCN film is eliminated, and the change with time of the stress is suppressed. Since this film is difficult to increase the Si—NH group due to the incorporation of N and H during the wiring formation process, amine is hardly released from the SiCN film, and poor poisoning can be suppressed.

Further, the SiCN film forming step is made into two stages, and the flow rate ratio of the source gas having an organic group in a part of the silane structure and He at the time of forming the SiCN film in the latter half step is set to 1: 4.2 or more, or By making the flow rate of the source gas, the number of bonds of organic groups in the source gas, and the flow rate of He 1: 1.4 or more, a slightly higher relative dielectric constant and stress formed in the upper layer are formed in the lower layer and lower. By adopting a two-layer structure supplemented by a structure having a relative dielectric constant and film stress, the SiCN film as a whole is intended to suppress the film thickness uniformity, relative dielectric constant, and stress to low values. In this case, the characteristic of the semiconductor device is that the Si—CH ₃ composition ratio of the upper SiCN film is smaller than that of the lower SiCN film.

  As a result, the present invention provides a semiconductor device having a SiCN film, which suppresses the occurrence of poisoning and reduces pattern defects, and a method for manufacturing the same. Further, in the present invention, it is possible to reduce the time-dependent change of stress of the SiCN film, suppress the stress migration of the Cu wiring, and further reduce the problem of the wiring layer peeling during the wiring forming process.

  According to the manufacturing method of the present invention, the SiCN film is obtained by setting the flow ratio of the source gas having organic groups in a part of the silane structure and He to a ratio of 1: 4.2 or more at the time of forming the SiCN film. By increasing the ratio of the number of bonds with the organic group of the gas and the flow ratio of He to 1: 1.4 or more, the ratio of He plasma is increased, and Si bonds that easily react with components in the air are reduced in the film. As a result, it is possible to suppress changes in the film stress over time, and to suppress poor poisoning.

In addition, the occurrence of antenna damage is avoided by making the SiCN film into two layers and absorbing the lowering of the film thickness uniformity when the He flow rate is increased with the properties of the lower layer. Specifically, in the SiCN film having a film thickness ratio of, for example, the lower layer 40 nm / upper layer 10 nm shown in the present embodiment, the film thickness uniformity is 1.87%, and the uniformity of the SiCN film formed by one kind of method (for example, 3.05%). As for the stress, since the upper SiCN film 22 does not react with N ₂ , H ₂ O, etc., the lower SiCN film 21 can maintain a low stress of −240 MPa and a low dielectric constant of 4.6 at the time of film formation without change over time. By combining the stress of the SiCN film 22 with -290 MPa and the relative dielectric constant of 5.0, the stress of this two-layer SiCN film can be -250 MPa and the relative dielectric constant of 4.7, which is lower than that of the first embodiment. That is, in this embodiment, a semiconductor device with little antenna damage, no poisoning, no stress change with time, better film thickness uniformity than the first embodiment, and has a small absolute value of stress and relative dielectric constant, and a method of manufacturing the same Can be provided.

(First embodiment)
A semiconductor device and a manufacturing method thereof according to the first embodiment of the present invention will be described with reference to FIG.

First, as shown in FIG. 1A, a barrier metal 2 made of TaN in a SiOC film 1 (C-containing silicon oxide film) having a thickness of 600 nm, for example, formed on a silicon substrate (not shown), and having a depth of 300 nm. A trench wiring 3 made of Cu is formed. In this embodiment, a SiOC film having a relative dielectric constant of about 2.7 is used as the low dielectric constant film. The upper portion of the wiring is covered with a cap layer 19 made of, for example, a SiCN film having a thickness of 50 nm in order to prevent Cu from diffusing into the second SiOC film 5. When the cap film 19 is formed, for example, using a parallel plate type CVD apparatus, the temperature is 330 ° C., the pressure is 3.0 Torr, power is applied to the upper electrode at 13.56 MHz, and the wafer is placed on the lower electrode side. To do. As a gas, 3MS (also referred to as TMS, trimethylsilane Si (CH ₃ ) ₃ H) / NH ₃ / He is flowed, but the present inventor fixed 3MS / NH ₃ at 175/330 sccm and adjusted the He flow rate. The point was increased from 470 sccm, and it was found that the change with time of the film stress was stabilized.

  Here, FIG. 2A shows a change with time of stress when a SiCN film of 200 nm is formed on a Si substrate and left in a clean room atmosphere. FIG. 2A shows time (number of days) on the horizontal axis and membrane stress (MPa) on the vertical axis, and it can be seen that the stress stabilizes at −290 MPa at a He flow rate of 740 sccm. The stress value itself is initially as low as −240 MPa at He: 470 sccm, but exceeds −300 MPa after 7 days as shown in FIG. 2A, and as a result, becomes greater than the film stress of −290 MPa at a He flow rate of 740 sccm. This stress change with time is thought to be due to absorption of components in the air, and it is not appropriate to use such an unstable film in a semiconductor process because the stress applied to the wiring increases. In particular, there is a problem that the stress migration and electromigration characteristics of the Cu wiring deteriorate. In addition, absorbed components may be released in a later process and have an adverse effect.

  The same can be considered for the relative dielectric constant. As shown in FIG. 2B, the relative dielectric constant is stable at about 5 at a He flow rate of 740 sccm, but according to the conventional conditions, it is 4.6 at He: 470 sccm. The initial value is low, but changes with time, and finally the relative dielectric constant is about 5. This is also considered to be because the SiCN film formed under the conventional conditions increased the relative dielectric constant because it absorbed moisture and N in the air.

  Actually, when the SiCN film formed under the conventional condition He: 470 sccm is applied to the multilayer wiring by the conventional method shown in FIG. 6, the groove pattern of the 0.14 μm diameter via hole chain wiring is formed in the step corresponding to FIG. The analysis results are shown in FIG.

  From FIG. 3A, it can be seen that the striped wiring groove pattern patterned by the conventional method is partially formed in a thin shape, which may cause a disconnection. This is considered that the resist poisoning defect which is the subject of the conventional method described with reference to FIG. 7 has occurred.

On the other hand, when the SiCN film is formed using the method of the present invention under the condition where the He flow rate is 740 sccm or more, as shown in FIG. 3B, it can be seen that the occurrence of poisoning failure can be effectively suppressed. Note that the He flow rate of 740 sccm is 4.2 in terms of the flow rate ratio of He / 3MS in accordance with the specific conditions in this embodiment, and 3MS is trimethylsilane Si (CH ₃ ) ₃ H. Since trimethylsilane has three Si-CH ₃ group, at a flow ratio to the number of Si-CH ₃ groups of the raw material gas at the time of the SiCN film 4.2 / 3 = 1.4 or more If He gas is supplied, for example, a stable film as shown in FIG. 3B can be obtained.

Further, in order to investigate the cause of the poor poisoning as shown in FIG. 3A, the amount of Si—NH group relative to the Si—C group in the SiCN film was examined. The ratio of Si—NH groups to —C groups increased from 0.84 to 1.19 after standing for 7.5 days. However, in the film having the deposition condition He: 740 sccm, Si—NH to Si—C groups was increased. It was found that the group ratio did not increase from 0.74 to 0.73. This phenomenon is thought to be due to the fact that the number of Si bonds that easily bind to the N ₂ and H ₂ O components in the air can be reduced by He plasma, among the Si bonds in the SiCN film.

  Actually, Table 1 shows the FT-IR analysis results of the SiCN film formed by the conventional method or the method of the present invention. Specifically, what are the bonds listed today for the Si-C bonds? It is shown whether it exists in a proper ratio.

In the case of the present invention, the ratio of Si—CH ₃ and Si—H groups to Si—C bonds is reduced as compared with the conventional method. It is considered that either Si—CH ₃ or Si—H groups, particularly Si—CH ₃ having a larger difference, is more effective in suppressing the stress change with time. In other words, there are some weak groups in Si—CH ₃ that take in N ₂ or H ₂ O in the air and become Si—NH bonds, but this is a film formed by He plasma under the condition that the He flow rate is increased. It is considered that such an unstable Si bond has been converted into an original Si—C—Si network or the like.

Table 2 shows the elemental composition analysis results of the SiCN film formed by the method of the present invention. From Table 2, it can be seen that the composition ratio of C to Si is reduced from 0.785 to 0.770 of the film formed by the conventional method. Further, the N content is reduced from 0.563 to 0.550. This is presumably because part of the unstable Si—CH ₃ group has already been bonded to NH in the film formed by the conventional method. In either case, if the flow rate of He is set to a certain ratio or more with respect to the silane-based organic source gas, the number of bonds that can be easily combined with the components in the air in the SiCN film is reduced and the film is stabilized. I can do it.

Other, it is conceivable to reduce the film stress by reducing the flow rate of NH _3, it is also considered a problem that simply film the leakage current to approach the SiC film reducing the flow rate of NH ₃ is increased. For example, when the NH ₃ flow rate was reduced to 300,270 sccm to form a film, the effect of suppressing the stress aging change was reduced. In other words, a desired film is not formed by using any means that simply reduces the amount of N having a high degree of freedom of reactivity, but is stable by controlling the He flow rate and the state of the reactive gas. A film can be obtained and a useful film as a whole device can be formed.

From the above, the deposition conditions of the SiCN film 19 are, for example, a temperature of 330 ° C., a pressure of 3.0 Torr, an electric power of 0.53 W / cm ² is applied to the upper electrode, the semiconductor device is installed on the lower electrode side, and a 3MS: He flow ratio The conditions of 3MS / NH ₃ / He of 175/330/740 sccm are selected so that = 1: 4.2, and a film is formed to a thickness of 50 nm. Thereafter, a second low dielectric constant film 5 having a thickness of 600 nm made of a SiOC film is formed to form an upper layer wiring and a via hole. When forming a via hole pattern in the second low dielectric constant film 5, an organic antireflection film 6 is applied, for example, 100 nm in order to prevent pattern formation failure due to reflected light from the underlying wiring during photolithography. Subsequently, a via hole pattern is formed with a photoresist 7 having a thickness of 600 nm.

Next, as shown in FIG. 1B, for example, dry etching of the second low dielectric constant film 5 is performed up to the surface of the SiCN film 19 with a plasma of a mixed gas such as CF ₄ + Ar + O ₂ + N ₂ to form via holes. 8 is opened. At this time, the surface of the SiCN film 19 is exposed to low-pressure O ₂ plasma ashing of about 100 mT in order to completely remove the photoresist. At that time, the SiCN film 19 damaged by the plasma exposure by dry etching is exposed to air. However, even in this case, the SiCN film 19 of the present invention is stable, and since the proportion of bonds that can be bonded to N or the like in the SiCN film is low, the incorporation of N ₂ , H ₂ O, and the like from the air is suppressed. The

  Next, as shown in FIG. 1C, the second organic antireflection film 10 is applied with a thickness of 100 nm, and the second photoresist 11 is formed with a thickness of 600 nm in order to form a pattern of the second layer wiring. Apply and expose using an ArF exposure machine. At this time, in the case of the conventional method, N mixed in the first SiCN film 19 is released from the via hole portion, and poisoning is generated above the via pattern. However, in the present invention, since a stable SiCN film that hardly captures N and H components from the atmosphere even when left in the atmosphere is used, N diffusion is suppressed and the occurrence of poisoning is greatly reduced. For the reasons described above, the occurrence of poisoning can be suppressed in this embodiment as shown in FIG.

  Next, FIGS. 1D to 1F are the same steps as shown in FIG. 6, but since the poisoning failure is suppressed, the upper layer which is normally made of the second barrier metal 14 and the second Cu 15 is used. A wiring and a via hole layer are formed (FIG. 1 (g)). Thereafter, the SiCN film 20 is formed on the surface of the upper wiring layer under the same conditions as the method for forming the SiCN film 19 (FIG. 1H).

By repeating the manufacturing steps as described above (FIGS. 1A to 1H), a method for manufacturing a semiconductor device having an SiCN film with a small decrease in the wiring pattern yield due to poisoning failure is obtained. Since this SiCN film has little change with time in stress, even when it is stored in a clean room for a long time with the SiCN exposed, the semiconductor device is damaged due to poor poisoning, or the stress increases, causing film peeling, or against Cu wiring Therefore, the problem that wiring stress and electromigration resistance deteriorate due to high stress is greatly reduced. Further, in the present invention, 3MS is used as the source gas, but tetramethylsilane (4MS: Si (CH ₃ ) ₄ ) may be used. At this time, since there are four CH ₃ bonds to Si, for example, for 4MS of 175 sccm, a He flow rate of 175 × 4 × 1.4 = 980 sccm or more may be used.

  In the present embodiment, the ammonia plasma reduction treatment of the Cu surface necessary for forming the SiCN film on the Cu wiring is not particularly described. However, after such pretreatment is performed, the SiCN film of the present invention is deposited. A method may be used.

(Second Embodiment)
A semiconductor device and a manufacturing method thereof according to the second embodiment of the present invention will be described with reference to FIG.

  First, as shown in FIG. 5A, a trench wiring having a depth of 300 nm made of TaN barrier metal 2 and Cu 3 is formed in a first low dielectric constant film 1 having a thickness of 600 nm formed on a silicon substrate (not shown). Is formed. Also in this embodiment, a SiOC film having a relative dielectric constant of about 2.7 is used as the first low dielectric constant film 1. In order to prevent Cu from diffusing into the second low dielectric constant film 5, a 50 nm thick SiCN film is deposited on the upper portion of the wiring. At this time, in this embodiment, the step of forming the SiCN film is set to 2 Steps.

For example, the temperature is 330 ° C., the pressure is 3.0 Torr, electric power of 0.53 W / cm ² is applied to the upper electrode, and the semiconductor device is disposed on the lower electrode side. In Step 1, film formation is performed at a thickness of 40 nm under the condition of 175/330/470 sccm under the film formation condition 3MS / NH ₃ / He of the conventional method. Subsequently, in Step 2, a film is formed to a thickness of 10 nm under the film formation conditions described in the first embodiment of the present invention, 3MS / NH ₃ / He at 175/330/740 sccm. Thus, the two-layered film has the following advantages.

When the He flow rate is increased, sufficient film thickness uniformity cannot be obtained. For example, the SiCN film measured by ellipsometry at the edge cut portion of 3 mm of the wafer has a range of 3.05% for He: 740 sccm and 1.58% for a He: 470 sccm film. In this case, the refractive indices of the films when the film was irradiated with a wavelength of 633 nm were 1.884 and 1.852, respectively. Such a film with insufficient uniformity cannot obtain a desired film uniformity, and there is a concern about a problem of antenna damage that causes an increase in leakage current of a gate oxide film in a pattern in which a long wiring is provided in a transistor. . Therefore, a film with good uniformity is deposited at the initial stage of film formation, which tends to change with time. After that, in the subsequent step of forming a film that finally becomes the uppermost layer, the film thickness uniformity is somewhat lowered so that the film does not react with N ₂ , H ₂ O, etc. in the air, but N _{2 in} the air , H ₂ O or the like is formed so that it is possible to suppress the occurrence of poisoning in the subsequent process due to amine diffusion.

Further, as shown in the present embodiment, the film thickness uniformity is 1.87% at a film thickness ratio of 40/10 nm, which is improved from 3.05% of the first embodiment. Regarding the stress, since the upper SiCN film 22 hardly reacts with N ₂ , H ₂ O, etc., the lower SiCN film 21 maintains a low stress of −240 MPa and a dielectric constant of 4.6 at the beginning of film formation while suppressing changes with time. it can. That is, since the stress of the upper SiCN film 22 is -290 MPa and the relative dielectric constant is 5.0, the stress of the two-layer SiCN film is -250 MPa and the relative dielectric constant is 4.7. Less damage, less poisoning, time-dependent changes in stress, and easier stabilization of film thickness and control of absolute value of stress and relative permittivity to a smaller value than when single layer is used. it can.

The SiCN film is defined as a semiconductor device having a two-layer structure, and the Si—CH ₃ composition ratio of the upper SiCN film is smaller than that of the lower SiCN film. Differences in film quality can also be defined.

  Here, FIG. 4 is a graph showing the relationship between the He flow rate during film formation and the refractive index, or the film deposition rate. From this graph, it can be seen that as the He flow rate increases, the refractive index of the film increases, and conversely, the deposition rate of the film decreases as the He flow rate increases. Therefore, as can be seen from the difference in refractive index shown in FIG. 4, it is defined as a semiconductor device characterized in that the refractive index at, for example, 633 nm of the upper SiCN film is larger than that of the lower SiCN film and is 1.848 or more. Also good. Alternatively, since the deposition rate becomes slower when the He flow rate is increased, it is considered that a film having a higher film density can be formed by increasing the He flow rate. Considering from this point of view, the present invention may be defined as a semiconductor device characterized in that the density of the upper SiCN film is higher than the density of the lower SiCN film. This is because when the density of the film is improved, N contained in the film forms a stronger interaction with surrounding molecules, and N atoms are not easily released from the film.

Specifically, the film density of the upper layer that forms an atomic structure capable of preventing the release of N is preferably 1.88 g / cm ³ or more. From Table 2, the upper SiCN film It can also be defined as a semiconductor device characterized in that the composition ratio of C and N is smaller than that of the lower SiCN film.

  After the formation of the SiCN film, a second low dielectric constant film 5 having a thickness of 600 nm is formed. When a via hole pattern is formed in the second low dielectric constant film 5, an organic antireflection film 6 is applied to a thickness of 100 nm in order to prevent pattern formation failure due to reflected light from a wiring layer serving as a base during photolithography. The Next, a via hole pattern is formed using a photoresist 7 having a thickness of 600 nm as a mask.

Next, as shown in FIG. 5B, for example, dry etching of the second low dielectric constant film 5 is performed up to the SiCN film 22 with plasma made of a mixed gas such as CF ₄ + Ar + O ₂ + N ₂ , and via holes are formed. 8 is opened. At this time, the surface of the SiCN film 22 is exposed to low-pressure O ₂ plasma ashing of about 100 mT for removing the photoresist. Also, the SiCN film 22 damaged by dry etching comes into contact with air. Even in this case, the SiCN film 22 of the present invention is stable and does not take in N ₂ , H ₂ O, etc. from the air.

  Next, as shown in FIG. 5C, the second organic antireflection film 10 is applied with a thickness of 100 nm, and the second photoresist 11 is formed with a thickness of 600 nm in order to form a pattern of the second layer wiring. Apply and expose using an ArF exposure machine. At this time, in the case of the conventional method, N is mixed in the first SiCN film 21 and N is released from the via hole portion to cause poisoning in the upper portion of the via pattern. In the present invention, however, the upper layer is stable. Since the SiCN film 22 is used, N diffusion is suppressed and poisoning does not occur. For the reasons described above, the occurrence of poisoning can be suppressed in this embodiment as shown in FIG.

  Next, FIGS. 5D to 5F are the same steps as shown in FIG. 6, but since the poisoning failure is suppressed, the upper layer normally made of the second barrier metal 14 and the second Cu 15 is used. A wiring and a via hole layer can be formed (FIG. 5G). Thereafter, the SiCN film 23 and the SiCN film 24 are formed on the upper wiring surface using the same conditions as those for forming the SiCN film 21 and the SiCN film 22 (FIG. 5H).

  By repeating the manufacturing steps (FIGS. 5A to 5H) as described above, a semiconductor device having a SiCN film and a manufacturing method therefor can be obtained that does not cause a decrease in the wiring pattern yield due to poor poisoning.

  Since this SiCN film greatly suppresses changes in stress over time, even if it is stored in a clean room for a long time with the SiCN exposed, the semiconductor device is damaged due to poor poisoning, stress increases, and film peeling occurs. High stress is applied to the wiring, so that problems such as wiring stress and electromigration resistance are less likely to occur. In addition to the advantages of the first embodiment, the antenna damage is small, the poisoning and the stress change with time are further suppressed, the film thickness uniformity is high, and the absolute value and relative dielectric constant of the stress are kept small. A semiconductor device and a manufacturing method thereof can be provided.

In this embodiment, 3MS is used as the source gas, but tetramethylsilane (4MS: Si (CH ₃ ) ₄ ) may be used. At this time, since there are four CH ₃ bonds to Si, for example, for 4MS of 175 sccm, a He flow rate of 175 × 4 × 1.4 = 980 sccm or more may be used. Further, in the present embodiment, the ammonia plasma reduction treatment of the Cu surface necessary for forming the SiCN film on the Cu wiring is not particularly described. However, after such pretreatment is performed, the SiCN film of the present invention is deposited. A method may be used. In the second embodiment, it has been described that the SiCN layer, that is, the layer containing Si, C, and N is composed of a two-layer film. However, at least a film structure that prioritizes film quality and impurities such as N are included. If a film that prioritizes the formation of a film having a difficult film is provided in the uppermost layer, it may be composed of two or more layers.

  As described above, the present invention is useful for providing a method and a structure for forming a wiring structure with high accuracy by suppressing poisoning in a Cu wiring forming method and a wiring structure having a dual damascene structure.

Sectional drawing of the process of the manufacturing method of the semiconductor device which concerns on the 1st Embodiment of this invention (A) The figure which shows the stress time-dependent change of the SiCN film of this invention, (b) The figure which shows the dielectric constant time-dependent change of the SiCN film of this invention (A) Pattern analysis diagram by the conventional method, (b) Pattern analysis diagram by the method of the present invention The figure which shows the refractive index and deposition rate of the SiCN film | membrane of this invention Sectional drawing of the process of the manufacturing method of the semiconductor device which concerns on 2nd Embodiment of this invention. Cross-sectional process diagram of conventional semiconductor device manufacturing method The figure which shows the stress time-dependent change of the conventional SiCN film | membrane

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st low dielectric constant film | membrane 2 TaN barrier metal 3 Cu trench wiring 4 1st SiCN film 5 2nd low dielectric constant film | membrane 6 Organic antireflection film 7 Photoresist 8 Via hole 10 2nd organic antireflection film 11 1st 2 photoresist 12 poisoning 13 wiring trench 14 second TaN barrier metal 15 second Cu
17 Second SiCN film 18 Insulation film remaining in wiring trench 19 First 3MS: SiCN film formed with He flow ratio 1: 4.2 20 Second 3MS: SiCN film formed with He flow ratio 1: 4.2 21 SiCN film formed by the first conventional method 22 SiCN film formed by the first 3MS: He flow ratio 1: 4.2 23 SiCN film formed by the second conventional method 24 Second 3MS: He SiCN film deposited at a flow ratio of 1: 4.2

Claims (14)

In the step of forming a film containing Si, C, and N by supplying a gas onto the substrate,
The gas is composed of at least a raw material gas and an inert gas,
A gas containing Si partially bonded to an organic group is used as one of the material gases,
A method of forming a film, wherein a flow rate ratio of the gas containing Si and the inert gas is 1: 4.2 or more. In the step of forming a film containing Si, C, and N by supplying a gas onto the substrate,
The gas is composed of at least a raw material gas and an inert gas,
A gas containing Si partially bonded to an organic group is used as one of the source gases,
A method for forming a film, wherein a ratio of a flow rate of the source gas x a number of bonds with an organic group of the source gas and a flow rate ratio of the inert gas is 1: 1.4 or more. In the process of forming a film containing Si, C, and N by supplying a gas onto the substrate using a plurality of steps,
The gas is composed of at least a raw material gas and an inert gas,
A gas containing Si partially bonded to an organic group is used as one of the source gases,
In at least the last step, the flow ratio of the Si-containing gas to the inert gas is set to 1: 4.2 or more. In the process of forming a film containing Si, C, and N by supplying a gas onto the substrate using a plurality of steps,
The gas is composed of at least a raw material gas and an inert gas,
A gas containing Si partially bonded to an organic group is used as one of the source gases,
In at least the last step, the film forming method is characterized in that the flow ratio of the raw material gas x the number of bonds with the organic group of the raw material gas and the flow ratio of the inert gas are 1: 1.4 or more. The film forming method according to claim 1, wherein the inert gas is He. 5. The film forming method according to claim 1, wherein the film is formed on a surface of a copper wiring formed on a substrate. Forming a first wiring layer on the substrate;
Forming a film containing Si, C and N on the first wiring layer;
Depositing a low dielectric constant film on the film containing Si, C and N;
Forming a connection port for connecting the first wiring layer and the second wiring layer before forming the second wiring layer in the low dielectric constant film;
Forming the second wiring layer so as to overlap the connection port,
In the step of forming the film containing Si, C, and N,
The gas is composed of at least a raw material gas and an inert gas,
A gas containing Si partially bonded to an organic group is used as one of the material gases,
A method for manufacturing a semiconductor device, wherein a flow rate ratio between the gas containing Si and the inert gas is 1: 4.2 or more. Forming a first wiring layer on the substrate;
Forming a film containing Si, C and N on the first wiring layer;
Depositing a low dielectric constant film on the film containing Si, C and N;
Forming a connection port for connecting the first wiring layer and the second wiring layer before forming the second wiring layer in the low dielectric constant film;
Forming the second wiring layer so as to overlap the connection port,
In the step of forming the film containing Si, C, and N,
The gas is composed of at least a raw material gas and an inert gas,
A gas containing Si partially bonded to an organic group is used as one of the material gases,
A method for forming a semiconductor device, wherein a ratio of a flow rate of the source gas to a number of bonds with an organic group of the source gas and a flow rate ratio of the inert gas is 1: 1.4 or more. The film containing Si, C, and N is composed of at least two layers, and at least the uppermost layer is formed by setting the flow rate ratio of the gas containing Si and the inert gas to 1: 4.2 or more. The method of manufacturing a semiconductor device according to claim 7, wherein the semiconductor device is manufactured. The film containing Si, C, and N is composed of at least two or more layers, and at least the uppermost layer has a flow rate of the source gas × the number of bonds with an organic group of the source gas, and a flow rate ratio of the inert gas. The method of manufacturing a semiconductor device according to claim 9, wherein the semiconductor device is formed by setting the ratio to 1: 1.4 or more. A first wiring layer; a film containing Si, C, and N formed on the first wiring layer; a low dielectric constant film formed on the film containing Si, C, and N; and the low dielectric A second wiring layer in the rate film, and a connecting portion for connecting the first wiring layer and the second wiring layer;
A semiconductor device, wherein a film density of the film containing Si, C, and N is 1.88 g / cm ³ or more. A first wiring layer; a film containing Si, C, and N formed on the first wiring layer; a low dielectric constant film formed on the film containing Si, C, and N; and the low dielectric A second wiring layer in the rate film, and a connecting portion for connecting the first wiring layer and the second wiring layer;
The film containing Si, C and N are composed of two or more layers, Si-CH ₃ Composition of Si and C and N film Si-CH ₃ composition ratio of Si and C and N film in the upper layer in the lower layer A semiconductor device characterized by being smaller than the ratio. A first wiring layer; a film containing Si, C, and N formed on the first wiring layer; a low dielectric constant film formed on the film containing Si, C, and N; and the low dielectric A second wiring layer in the rate film, and a connecting portion for connecting the first wiring layer and the second wiring layer;
The film containing Si, C, and N is composed of two or more layers, and the Si, C, and N films in the upper layer have a film density larger than the film density of the Si, C, and N films in the lower layer. A semiconductor device characterized by the above. The semiconductor device according to claim 13, wherein a film density of the film containing Si, C, and N in the upper layer is 1.88 g / cm ³ or more.