JP2009246178A - Semiconductor device and its manufacturing method - Google Patents

Abstract

A semiconductor device having a contact plug with low resistance and high reliability and a method for manufacturing the same are provided.
A method for manufacturing a semiconductor device includes a step of forming an insulating film over a semiconductor substrate provided with a contact hole, a step of forming a first conductive film over the entire surface of the substrate, and a first step. Forming a metal nitride film 106 over the conductive film 104, forming a second conductive film 107 filling the contact hole 103 over the metal nitride film 106, and forming the second conductive film 107 and the metal nitride film 106. And a step (e) of forming a contact plug 109 by removing a part of the first conductive film 104. The value of (film thickness of the metal nitride film provided on the bottom surface of the contact hole) / (film thickness of the first conductive film provided on the bottom surface of the contact hole) is larger than 0.8 and smaller than 2.5 .
[Selection] Figure 1

Description

  The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly to a method of forming a contact plug in a fine contact hole.

  With the recent miniaturization of semiconductor devices, the contact plug opening diameter for making contact with a silicon substrate has also been miniaturized.

In the contact plug, an interlayer insulating film is deposited on a silicon substrate, a groove having a contact pattern is formed, tungsten (W) is buried in the groove, and then W is polished and removed by a CMP (Chemical Mechanical Polishing) method. To form. Here, when W is used as a wiring material, a titanium (Ti) film or a titanium nitride (TiN) film is used as an adhesion layer under the W film (see Patent Document 1). Here, the Ti film is necessary for making ohmic contact with the substrate. On the other hand, the TiN film has a function as a barrier film for preventing a reaction between a reactive gas (WF ₆ gas) and a Ti layer when depositing the W film.
Japanese Patent Laid-Open No. 2005-203647

  However, the technique disclosed in Patent Document 1 has the following problems.

  Currently, with the miniaturization of the entire semiconductor device, the contact plug opening diameter is also miniaturized. The contact diameter, which was about 80 nm in the 65 nm generation design rule, is reduced to about 50 nm in the 32 nm generation design rule. When the conventional technique is applied to such a fine contact hole, the contact resistance, which was about 90Ω in the 65 nm generation, rapidly increases to about 1500Ω in the 32 nm generation. On the other hand, in order to maintain the characteristics of the semiconductor device, the contact resistance is desirably about 200Ω or less. Therefore, when a 32-nm generation contact plug is formed using the technique disclosed in Patent Document 1, the characteristics of the obtained device are low.

  The reason why the contact resistance increases when the technique disclosed in Patent Document 1 is used is that the thickness of the TiN film used is at least 10 nm. This situation will be described below.

  FIGS. 3A and 3B are cross-sectional views (horizontal cross-sectional views) showing 65 nm generation and 32 nm generation contact plugs formed by conventional techniques, respectively. The specific resistance of each metal film constituting the contact plug is 15 μΩcm for the W film 501, 150 μΩcm for the Ti film, and 300 μΩcm for the TiN film 503. 3A and 3B, it can be seen that the cross section of the contact plug has a shape in which a low resistance W film is covered with a high resistance TiN film. Here, since the film thickness of the Ti film formed on the side wall of the contact hole is thinner than the film thickness of the TiN film 503, the description of the Ti film is omitted. In the conventional technique, when the TiN film 503 is deposited at the bottom of the contact hole by 10 nm, the TiN film 503 having a thickness of 20 nm is deposited on the side wall with the Ti film interposed therebetween. 3A and 3B, the ratio of the cross-sectional area of the TiN film 503 on the side wall of the contact hole to the cross-sectional area of the contact plug ((the cross-sectional area of the TiN film) / (the cross-sectional area of the contact plug)) It can be seen that the value increased from 75% in the 65 nm generation to 96% in the 32 nm generation. As described above, an increase in the proportion of the high resistance TiN film in the cross-sectional area of the contact plug causes a rapid increase in contact resistance.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor device having a contact plug with low resistance and high reliability, and a method for manufacturing the same.

  A first semiconductor device of the present invention includes a semiconductor substrate, an insulating film provided on the semiconductor substrate and having a contact hole penetrating from the upper surface side to the lower surface side, and a first film provided on the inner surface of the contact hole. A first conductive film, a metal nitride film provided on the first conductive film along an inner surface of the contact hole, and a second conductive film provided on the metal nitride film and filling the contact hole; And a contact plug connected to the semiconductor substrate, and (the film thickness of the portion of the metal nitride film provided on the bottom surface of the contact hole) / (the first conductive film The value of the film thickness of the portion provided on the bottom surface of the contact hole is larger than 0.8 and smaller than 2.5.

  With this configuration, even when the design rule is reduced, the contact resistance does not increase and the occurrence of contact plug surface abnormality can be suppressed. Therefore, the reliability of the semiconductor device of the present invention is greatly improved as compared with the conventional semiconductor device.

  In the semiconductor device of the present invention, for example, the diameter of the upper end portion of the contact hole may be 50 nm or less.

  In particular, if the total thickness of the portions of the first conductive film and the metal nitride film formed on the side wall of the contact hole is larger than 10% and smaller than 50% of the radius of the contact hole, An increase in contact resistance can be suppressed.

  The thickness of the portion of the metal nitride film formed on the bottom of the contact hole is larger than 1.5 nm and smaller than 5 nm, so that an increase in contact resistance can be suppressed.

  If a Ni silicide layer is further provided between the contact plug and the semiconductor substrate, the contact resistance between the semiconductor substrate and the contact plug can be further reduced.

  The first conductive film may contain Ti.

  The metal nitride film may contain Ti.

  The second conductive film may contain W.

  A second semiconductor device of the present invention includes a semiconductor substrate, an insulating film provided on the semiconductor substrate and having a contact hole penetrating from the upper surface side to the lower surface side, and a nitridation provided on the inner surface of the contact hole A contact plug provided on the metal nitride film and having a conductive film filling the contact hole, the contact plug being connected to the semiconductor substrate; and on a bottom surface of the contact hole in the metal nitride film The value of (the number of metal atoms) / (the number of nitrogen atoms), which is the composition ratio between the metal atom and the nitrogen atom in the portion provided in FIG.

  With this configuration, in addition to the metal nitride film serving as an adhesion layer of the conductive film, it also functions as a barrier film when forming the conductive film, thereby preventing contact plug surface abnormalities while preventing an increase in contact resistance. Can be suppressed.

  According to a first method of manufacturing a semiconductor device of the present invention, a step (a) of forming an insulating film on a semiconductor substrate provided with a contact hole, and a first method on the inner surface of the contact hole and the upper surface of the insulating film are provided. A step (b) of forming a conductive film, a step (c) of forming a metal nitride film on the first conductive film in a region including the contact hole, and filling the contact hole on the metal nitride film. A step (d) of forming a second conductive film; and removing the second conductive film, the metal nitride film, and a part of the first conductive film to fill the contact hole, A step (e) of forming a contact plug connected to the semiconductor substrate, and in the step (c), (the film thickness of the portion of the metal nitride film provided on the bottom surface of the contact hole) / ( The first A method of manufacturing a semiconductor device, wherein the metal nitride film is formed so that a value of a film thickness of a portion of the conductive film provided on the bottom surface of the contact hole is within a range greater than 0.8 and less than 2.5 .

  By this method, even if the miniaturization is advanced, it is possible to suppress an increase in contact resistance and to prevent occurrence of contact plug surface abnormality when forming the second conductive film in the step (d). .

  The diameter of the upper end portion of the contact hole is preferably 50 nm or less, for example.

  The total thickness of portions of the first conductive film and the metal nitride film formed on the side wall of the contact hole is preferably larger than 10% and smaller than 50% of the radius of the contact hole.

  The film thickness of the portion formed on the bottom of the contact hole in the metal nitride film formed in the step (c) is preferably larger than 1.5 nm and smaller than 5 nm.

  It is preferable that a Ni silicide layer is further formed on the semiconductor substrate and below the insulating film.

  The first conductive film formed in the step (b) may contain Ti.

  The metal nitride film formed in the step (c) may contain Ti.

  The second conductive film formed in the step (d) may contain W.

  According to a second method of manufacturing a semiconductor device of the present invention, a step (a) of forming an insulating film on a semiconductor substrate provided with a contact hole, and a metal nitride film on the inner surface of the contact hole and the upper surface of the insulating film Forming a conductive film that fills the contact hole on the metal nitride film, removing a part of the conductive film and the metal nitride film, A step (d) of forming a contact plug embedded in the contact hole and connected to the semiconductor substrate, and provided on the bottom surface of the contact hole in the metal nitride film formed in the step (b). The value of (the number of metal atoms) / (the number of nitrogen atoms), which is the composition ratio between the metal atom and the nitrogen atom in the obtained portion, is larger than 1.4 and smaller than 2.4.

  According to this method, it is possible to suppress the occurrence of contact plug surface abnormality while preventing an increase in contact resistance.

  The diameter of the upper end portion of the contact hole is preferably 50 nm or less, for example.

  A Ni silicide layer may be further formed on the semiconductor substrate and below the insulating film.

  The metal nitride film may contain Ti.

  The second conductive film formed in the step (d) may contain W.

  According to the method of manufacturing a semiconductor device according to the present invention, since the increase in contact resistance and the occurrence of surface abnormality during contact plug formation are suppressed, a contact plug with low resistance and high reliability can be formed.

(First embodiment)
A method for manufacturing a semiconductor device according to the first embodiment of the present invention will be described below with reference to the drawings.

  1A to 1F are cross-sectional views illustrating a method for manufacturing a semiconductor device according to the present embodiment.

  First, as shown in FIG. 1A, nickel (Ni) is deposited by physical vapor deposition on a semiconductor substrate 100 on which elements such as transistors are formed. Thereafter, a NiSi layer 101 is formed on the semiconductor substrate 100 by heat treatment at about 500 ° C. The thickness of the NiSi layer 101 is, for example, 30 nm.

  Next, an interlayer insulating film 102 having a thickness of 300 nm is formed on the semiconductor substrate 100 by a plasma CVD (Chemical Vapor Deposition) method. Here, as the interlayer insulating film 102, for example, USG (Undoped Silicon Glass) is used.

  Next, a contact pattern having an opening with a diameter of 50 nm is formed on the interlayer insulating film 102 using a photoresist. Thereafter, a part of the interlayer insulating film 102 is removed by dry etching using the contact pattern, thereby forming a contact hole 103 reaching the upper surface of the NiSi layer 101. That is, the diameter of the upper end portion of the contact hole 103 is 50 nm. Thereafter, the NiSi layer 101 at the bottom of the contact hole 103 is cleaned by sputtering.

  Next, as shown in FIG. 1B, a Ti film 104 is formed on the inner surface of the contact hole 103 by using directional sputtering. At this time, the Ti film 104 is formed under the following conditions: DC power 2300 kW, argon (Ar) flow rate 40 sccm (mL / min), and the upper surface of the interlayer insulating film 102 and the contact so that the film thickness of the Ti film 104 is 12 nm. A Ti film 104 is formed on the inner surface of the hole 103. In this case, a Ti film 104 is formed with a thickness of, for example, 3 nm on the bottom of the contact hole 103. Here, the thickness of the Ti film at the bottom of the contact hole 103 is not limited to 3 nm and may be 2 nm or more. Note that when the directional sputtering method is used, the Ti film 104 is hardly formed on the sidewall of the contact hole 103, or even if it is formed, it is very thin.

Next, as shown in FIG. 1C, a TiN film 105 containing a large amount of carbon (C) and having a high resistance is deposited on the Ti film 104 by a CVD method using tetrakisdimethylaminotitanium (TDMAT). Here, a TiN film 105 having a high resistance is deposited on the bottom of the contact hole 103, for example, 1.5 nm. Thereafter, as shown in FIG. 1D, the TiN film 105 is exposed to plasma of H ₂ and N ₂ to remove carbon from the TiN film 105 having a high resistance, and thereby the TiN film 106 having a low resistance. To reform. Here, by repeating the cycle of forming the TiN film 105 having a high resistance and then modifying the TiN film 106 having a low resistance twice, the bottom of the contact hole 103 has a low resistance with a total thickness of 3 nm. A TiN film 106 is formed. At this time, the TiN film 106 is formed on the side wall of the contact hole 103 with a thickness of about twice the bottom, that is, about 6 nm.

The thickness of the portion of the TiN film 106 formed at the bottom of the contact hole 103 is not limited to 3 nm (the thickness of the portion formed on the sidewall of the contact hole is 6 nm), but is 1.5 nm (formed on the sidewall of the contact hole). The film thickness of the formed portion must be larger than 3 nm) and smaller than 5 nm (the film thickness of the portion formed on the side wall of the contact hole is 10 nm). In other words, the total film thickness of the Ti film 104 and the TiN film 106 formed on the sidewall of the contact hole 103 is larger than about 10% of the radius of the contact hole 103 and smaller than about 50%. Need to be. Further, the TiN-Ti ratio (the ratio of the thickness of the TiN film 106 formed at the bottom of the contact hole to the thickness of the Ti film 104 formed at the bottom of the contact hole 103 (= (the thickness of the TiN film) / (Ti The film thickness is preferably set so as to be in a range larger than 0.8 and smaller than 2.5. The reason for setting the above range will be described below. The thickness of the TiN film 106 formed on the side wall of the contact hole 103 is about twice the thickness of the TiN film 106 formed on the bottom of the contact hole 103. This is because plasma is applied to the side wall portion of the contact hole 103. This is due to the fact that a large amount of carbon remains, that is, the contact hole from which a large amount of carbon is desorbed because the film shrinks and becomes thin when the carbon in the film escapes. 03 the film thickness of the TiN film 106 is thinner than the side wall portion at the bottom of. In the plasma treatment conditions in the reforming process of the TiN film 105 is, for example, flow rate of _{H 2 1800sccm (mL / min), N} 2 flow rate 1200 sccm (mL / min), pressure 173 Pa (1.3 Torr), plasma power 1750 W, treatment time 30 seconds.

  Next, as shown in FIG. 1E, a W film 107 is formed so as to bury the contact hole 103 by W-CVD or W-ALD (Atomic Layer Deposition). The film thickness of the W film 107 is 200 nm.

  Next, as shown in FIG. 1F, the W film 107, the Ti film 104, and the TiN film 106 are polished by CMP to contact holes in the W film 107, the Ti film 104, and the TiN film 106. A portion formed outside of 103 is removed, and contact plug 109 is formed.

  The contact plug 109 formed by the method of the first embodiment described above has a lower resistance than the conventional example, and an occurrence of an abnormality on the contact plug surface during the formation is suppressed. The reason will be described below.

  In the prior art described in Patent Document 1, when the diameter of the contact hole is assumed to be 50 nm, the thickness of the TiN film formed on the side wall of the contact hole is about 10 nm. Further, although a Ti film is formed between the TiN film and the contact hole, the TiN—Ti ratio is not defined.

  In contrast, in the manufacturing method of the present embodiment, the thickness of the TiN film 106 formed at the bottom of the contact hole 103, that is, the bottom of the contact plug 109 is larger than 1.5 nm (the thickness of the contact hole side wall is 3 nm). It is made smaller than 5 nm (the thickness of the contact hole side wall is 10 nm). In other words, the total film thickness of the Ti film 104 and the TiN film 105 formed on the side wall of the contact hole 103 is larger than about 10% of the radius of the contact hole 103 and smaller than about 50%. It is said. In addition, the TiN film thickness-Ti film thickness ratio is in a range larger than 0.8 and smaller than 2.5. The above range is determined by the following three factors.

  The first factor is the influence of the thickness of the Ti film on the contact resistance. FIG. 4 shows measurement data of contact resistance with respect to the thickness of the Ti film formed on the bottom of the contact plug. The horizontal axis indicates the thickness of the Ti film formed on the bottom of the contact plug, and the vertical axis indicates the contact resistance value with respect to the thickness of each Ti. In this measurement, the diameter of the contact hole is about 50 nm.

  As can be seen from FIG. 4, when the Ti film thickness at the bottom of the contact plug is less than 2 nm, the contact resistance increases. Ti has a role of reducing the surface oxide film of NiSi to make an ohmic contact. However, when Ti is insufficient, the reduction action is insufficient, so that contact resistance is considered to increase. . The result that the Ti film thickness is preferably 2 nm or more is considered to be applicable regardless of the diameter of the contact hole.

  The second factor is the influence of the TiN film thickness on the contact resistance. FIG. 5 shows measurement data on the dependency of the contact resistance on the TiN film thickness when the contact diameter is about 50 nm (47 nm). The horizontal axis indicates the thickness of the TiN film formed on the bottom of the contact plug, and the vertical axis indicates the contact resistance value Rc with respect to the thickness of each TiN film.

As can be seen from FIG. 5, when the TiN film thickness at the bottom of the contact plug is less than 1.5 nm (the film thickness on the side wall of the contact hole is 3 nm) and when the film thickness exceeds 5 nm (the film thickness on the side wall of the contact hole is 10 nm). The contact resistance value increased. When the TiN film thickness is too thin, it is considered that the contact resistance is increased from lowering of barrier property against WF _6. On the other hand, when the TiN film thickness is too thick, as described above, the ratio of the high-resistance TiN film to the cross-sectional area of the contact plug increases, so that the contact resistance increases. This result can be applied regardless of the diameter of the contact hole.

The third factor is the influence of the TiN and Ti film thicknesses on the occurrence of surface abnormality during contact plug formation. FIG. 6 is a diagram showing the relationship between the Ti film thickness and TiN film thickness and the occurrence of surface abnormalities. The horizontal axis represents the Ti film thickness at the bottom of the contact plug, and the vertical axis represents the TiN film thickness at the bottom of the contact plug. ○ indicates that no abnormality occurred on the surface of the contact plug with respect to each Ti film thickness and TiN film thickness. X indicates that an abnormality occurred on the surface of the contact plug with respect to each Ti film thickness and TiN film thickness. The contact plug surface abnormality is caused by the formation of fluoride by the reaction of WF ₆ gas and Ti when the barrier property of the TiN film is insufficient. This surface abnormality is likely to occur when the TiN film formed on the contact hole sidewall is thinner than the Ti film formed on the contact hole sidewall. It can be seen from FIG. 6 that this occurs when the TiN-Ti ratio is less than 0.8. When the Ti film formed on the bottom of the contact hole becomes thicker, the overhang of the Ti film at the upper end of the contact hole becomes larger. As a result, the step coverage of the TiN film deteriorates at the upper end of the contact hole, and the Ti film is partially exposed. Therefore, it is considered that the WF ₆ gas reacts with the exposed portion of the Ti film during the deposition of the W film, resulting in surface abnormality. Further, since the TiN film thickness at the bottom of the contact plug is substantially proportional to the TiN film thickness at the side wall of the contact plug, the TiN film at the bottom of the contact plug can be used as an indicator of contact plug surface abnormality. Therefore, when the value of TiN film thickness / Ti film thickness is 0.8 or more at the bottom of the contact plug, it is considered that generation beyond the surface of the contact plug can be suppressed. This result is also considered to be applicable regardless of the diameter of the contact hole.

  In consideration of the above three factors, the thickness regions of Ti and TiN that can suppress the increase in contact resistance and suppress the occurrence of surface abnormality during contact plug formation are shown by hatched portions in FIG. It can be seen that this region is within a range where the ratio of TiN film thickness-Ti film thickness (= TiN film thickness / Ti film thickness) is larger than 0.8 and smaller than 2.5. Therefore, according to the manufacturing method of the present embodiment described above, even when the diameter of the contact hole is reduced to, for example, 50 nm or less, the occurrence of surface abnormality during contact plug formation is suppressed while suppressing an increase in contact resistance. It is possible to do. Note that the plug structure of the present invention can also be applied to a via connecting upper wirings when a metal nitride film is used as a barrier film.

  In addition, as shown in FIG. 1F, the semiconductor device manufactured by the method of this embodiment includes a NiSi layer 101 that is a metal silicide layer formed on a semiconductor substrate 100 on which a semiconductor element such as a transistor is formed. And an interlayer insulating film 102 formed on the semiconductor substrate 100 and the NiSi layer 101; a contact hole 103 that penetrates the interlayer insulating film 102 and reaches the upper surface of the NiSi layer 101; The contact plug 109 is provided. The contact plug 109 is connected to, for example, a source / drain region or a gate electrode of a transistor.

  The contact plug 109 includes a Ti film (first conductive film) 104 provided on the inner surface of the contact hole 103, a TiN film 106 provided on the Ti film 104 along the inner surface of the contact hole 103, and a TiN film. And a W film (second conductive film) 107 provided on 106 and filling contact hole 103. Instead of the TiN film 106, a metal nitride film having a barrier property against the source gas of the W film may be used.

  Further, at the bottom of the contact plug 109, (the thickness of the TiN film 106) / (the thickness of the Ti film 104) is in a range larger than 0.8 and smaller than 2.5. The total film thickness of the portion of the Ti film 104 provided on the side wall of the contact hole 103 and the thickness of the portion of the TiN film 106 provided on the side wall of the contact hole 103 is calculated as follows. The radius is larger than 10% and smaller than 50%. For example, when the contact hole 103 has a diameter of 50 nm, the thickness of the TiN film 106 provided at the bottom of the contact hole 103 is preferably larger than 1.5 nm and smaller than 5 nm. In addition, the NiSi layer 101 may be replaced with a layer made of Ni silicide having a different phase or another metal silicide, and the NiSi layer 101 may not be provided depending on the location where the contact plug 109 is provided. Note that the ratio of Ti atoms to N atoms in the TiN film 106 is approximately 1: 1, for example.

  In the semiconductor device of this embodiment, as described above, even when the design rule is miniaturized and the diameter of the contact plug is reduced, the surface abnormality of the contact plug 109 is less likely to occur, and compared with the case where the conventional technique is applied. Therefore, the increase in contact resistance is greatly suppressed.

(Second Embodiment)
2A to 2D are cross-sectional views illustrating a method for manufacturing a semiconductor device according to the second embodiment of the present invention. The manufacturing method of the present embodiment is obtained by examining a method of forming a contact plug without providing a Ti film based on the measurement results shown in FIGS.

  First, as shown in FIG. 2A, Ni is deposited by physical vapor deposition on a semiconductor substrate 200 on which elements such as transistors are formed. Thereafter, a NiSi layer 201 is formed on the semiconductor substrate 200 by heat treatment at about 500 ° C. The film thickness of the NiSi layer 201 is, for example, 30 nm.

  Next, an interlayer insulating film 202 having a film thickness of 300 nm is formed on the semiconductor substrate 200 by plasma CVD. Here, USG is used as the interlayer insulating film 202.

  Next, a contact pattern having an opening with a diameter of 50 nm is formed on the interlayer insulating film 202 using a photoresist. Thereafter, a part of the interlayer insulating film 202 is removed by dry etching using the contact pattern, thereby forming a contact hole 203 reaching the upper surface of the NiSi layer 201. That is, the diameter of the upper end portion of the contact hole 203 is 50 nm. Thereafter, the NiSi layer 201 at the bottom of the contact hole 203 is cleaned by sputtering.

Next, as shown in FIG. 2B, a TiN film 204 is formed on the inner surface of the contact hole 203 by sputtering or the like. The thickness of the portion formed on the bottom of the contact hole in the TiN film 204 is 3 nm, and the thickness of the portion formed on the side wall of the contact hole is almost twice that (6 nm). Is not limited to this value. However, the thickness of the portion of the TiN film 204 formed on the bottom of the contact hole 203 is greater than 1.5 nm (the thickness of the portion formed on the side wall of the contact hole 203 is 3 nm) and 5 nm (formed on the side wall of the contact hole 203). The film thickness of the portion thus formed must be smaller than 10 nm). In other words, the thickness of the TiN film 204 formed on the sidewall of the contact hole 203 needs to be greater than about 10% and less than about 50% of the radius of the contact hole (the radius of the upper end portion of the contact hole). is there. Here, the Ti / N ratio (atom composition ratio) in the TiN film 204 needs to be in a range larger than 1.4 and smaller than 2.4. The reason for setting this range will be described below. The nitrogen concentration in the TiN film 204 can be controlled by controlling the nitrogen partial pressure in the chamber during film formation. In the case where the TiN film 204 is formed by the MO-CVD method, the film quality is improved after being formed by N ₂ / H ₂ plasma or the like.

  Next, as shown in FIG. 2C, a W film 205 is deposited so as to fill the contact hole 203 by the W-CVD method or the W-ALD method. The film thickness of the W film 205 is 200 nm.

  Next, as shown in FIG. 2D, portions of the W film 205 and TiN film 204 formed outside the contact hole 203 are removed by CMP to form contact plugs 207.

  The contact plug formed by the method of the second embodiment described above has a lower resistance than that of the conventional example, and the occurrence of an abnormality on the surface of the contact plug is suppressed when formed. The reason will be described below.

  Conventionally, when a single layer film made of TiN is used as the adhesion layer, the value of the Ti / N ratio is usually not specified. On the other hand, in the manufacturing method of the present embodiment, the Ti / N ratio of the TiN film at the bottom of the contact hole 203, that is, the bottom of the contact plug 207 is set in a range larger than 1.4 and smaller than 2.4.

When a TiN / Ti laminated film is used as the adhesion layer as in the first embodiment, it is considered that the nitrogen atom in the TiN film plays the role of the barrier property against WF ₆ . Therefore, nitrogen atoms do not have to be unevenly distributed in the TiN film in the TiN / Ti laminated film, and it is considered that the same barrier property can be obtained even when the TiN film is uniformly distributed throughout the laminated film. This corresponds to the case where a single layer film of TiN is used as the adhesion layer as in the present embodiment. As described in the first embodiment, the film thickness region of Ti and TiN that can suppress the increase in contact resistance and suppress the occurrence of surface abnormality during plug formation has a TiN-Ti ratio of 0.8. It is within the range of larger than 2.5. When this film thickness ratio is converted into a Ti / N ratio in the film, it is in a range larger than 1.4 and smaller than 2.4.

Here, when using a Ti film and a TiN film, the amount of Ti in the film is
(1 × titanium density / mass of titanium per mol) + {TiN / Ti ratio × density of titanium nitride / (mass of titanium per mol + 1 mass of nitrogen per mol)} (1)
And the amount of N is
TiN / Ti ratio × density of titanium nitride / (mass of titanium per mol + 1 mass of nitrogen per mol) (2)
Is required. Here, the TiN / Ti ratio of 0.8 when using the Ti film and the TiN film corresponds to the Ti / N ratio of 2.4 in the TiN film when only the TiN film is used. A TiN / Ti ratio of 2.5 when using a Ti film and a TiN film corresponds to a Ti / N ratio of 1.4 in the TiN film when using only a TiN film. Therefore, in the TiN film 204 of the present embodiment, if the Ti / N ratio is in a range larger than 1.4 and smaller than 2.4, contact characteristics similar to those of the first embodiment can be obtained, and the contact plug The occurrence of surface abnormality can also be suppressed.

  As described above, the present invention is useful for all semiconductor devices having contact plugs.

(A)-(f) is sectional drawing which shows the manufacturing method of the semiconductor device which concerns on this embodiment. (A)-(d) is sectional drawing which shows the manufacturing method of the semiconductor device which concerns on the 2nd Embodiment of this invention. (A), (b) is sectional drawing (horizontal sectional drawing) which shows what formed the contact plug of 65 nm generation and 32 nm generation, respectively by the prior art. It is a figure which shows the measurement data of contact resistance with respect to the film thickness of Ti film | membrane formed in the contact plug bottom part. It is a figure which shows the measurement data about the TiN film thickness dependence of contact resistance. It is a figure showing the relationship between Ti film thickness and TiN film thickness, and generation | occurrence | production of surface abnormality. It is a figure which shows the film thickness area | region of the TiN film | membrane and Ti film | membrane in the semiconductor device of 1st Embodiment.

Explanation of symbols

100, 200 semiconductor substrate
101, 201 NiSi layer
102, 202 Interlayer insulating film
103, 203 Contact hole
104 Ti film
105,204 TiN film
106,204 TiN film
107, 205 W film
109 Contact plug

Claims (22)

A semiconductor substrate;
An insulating film provided on the semiconductor substrate and having a contact hole penetrating from the upper surface side to the lower surface side;
A first conductive film provided on the inner surface of the contact hole; a metal nitride film provided on the first conductive film along the inner surface of the contact hole; and provided on the metal nitride film, A second conductive film filling the contact hole, and a contact plug connected to the semiconductor substrate,
The value of (film thickness of the portion of the metal nitride film provided on the bottom surface of the contact hole) / (film thickness of the portion of the first conductive film provided on the bottom surface of the contact hole) A semiconductor device larger than 0.8 and smaller than 2.5.   The semiconductor device according to claim 1, wherein a diameter of an upper end portion of the contact hole is 50 nm or less.   A total thickness of portions of the first conductive film and the metal nitride film formed on the side wall of the contact hole is larger than 10% and smaller than 50% of the radius of the contact hole. The semiconductor device according to claim 1 or 2.   3. The semiconductor device according to claim 2, wherein a thickness of a portion of the metal nitride film formed on a bottom portion of the contact hole is larger than 1.5 nm and smaller than 5 nm.   The semiconductor device according to claim 1, further comprising a Ni silicide layer provided between the contact plug and the semiconductor substrate.   The semiconductor device according to claim 1, wherein the first conductive film contains Ti.   The semiconductor device according to claim 1, wherein the metal nitride film contains Ti.   The semiconductor device according to claim 1, wherein the second conductive film includes W. A semiconductor substrate;
An insulating film provided on the semiconductor substrate and having a contact hole penetrating from the upper surface side to the lower surface side;
A metal nitride film provided on the inner surface of the contact hole, a conductive film provided on the metal nitride film and filling the contact hole, and a contact plug connected to the semiconductor substrate,
The value of (metal atom number) / (number of nitrogen atoms), which is the composition ratio of the metal atoms and nitrogen atoms in the portion of the metal nitride film provided on the bottom surface of the contact hole, is larger than 1.4 and 2 A semiconductor device smaller than .4. A step (a) of forming an insulating film on the semiconductor substrate provided with the contact hole;
A step (b) of forming a first conductive film on the inner surface of the contact hole and the upper surface of the insulating film;
A step (c) of forming a metal nitride film on the first conductive film in a region including the contact hole;
Forming a second conductive film filling the contact hole on the metal nitride film (d);
Removing a part of the second conductive film, the metal nitride film, and the first conductive film to form a contact plug embedded in the contact hole and connected to the semiconductor substrate (e )
In the step (c), (the film thickness of the portion of the metal nitride film provided on the bottom surface of the contact hole) / (the portion of the first conductive film provided on the bottom surface of the contact hole) The method of manufacturing a semiconductor device, wherein the metal nitride film is formed so that the value of the film thickness is within a range greater than 0.8 and less than 2.5.   The method of manufacturing a semiconductor device according to claim 10, wherein a diameter of an upper end portion of the contact hole is 50 nm or less.   A total thickness of portions of the first conductive film and the metal nitride film formed on the side wall of the contact hole is larger than 10% and smaller than 50% of the radius of the contact hole. A method for manufacturing a semiconductor device according to claim 10 or 11.   The film thickness of a portion formed on the bottom of the contact hole in the metal nitride film formed in the step (c) is greater than 1.5 nm and less than 5 nm. A method for manufacturing a semiconductor device.   14. The method of manufacturing a semiconductor device according to claim 10, further comprising a Ni silicide layer formed on the semiconductor substrate and below the insulating film.   15. The method of manufacturing a semiconductor device according to claim 10, wherein the first conductive film formed in the step (b) contains Ti.   16. The method of manufacturing a semiconductor device according to claim 10, wherein the metal nitride film formed in the step (c) contains Ti.   The method for manufacturing a semiconductor device according to claim 10, wherein the second conductive film formed in the step (d) includes W. A step (a) of forming an insulating film on the semiconductor substrate provided with the contact hole;
Forming a metal nitride film on the inner surface of the contact hole and the upper surface of the insulating film;
Forming a conductive film filling the contact hole on the metal nitride film (c);
(D) forming a contact plug embedded in the contact hole and connected to the semiconductor substrate by removing a part of the conductive film and the metal nitride film;
Of the metal nitride film formed in the step (b), the composition ratio of the metal atoms and nitrogen atoms in the portion provided on the bottom surface of the contact hole (number of metal atoms) / (number of nitrogen atoms) A value of is greater than 1.4 and less than 2.4.   The method of manufacturing a semiconductor device according to claim 18, wherein a diameter of an upper end portion of the contact hole is 50 nm or less.   20. The method of manufacturing a semiconductor device according to claim 10, further comprising a Ni silicide layer formed on the semiconductor substrate and below the insulating film.   21. The method of manufacturing a semiconductor device according to claim 18, wherein the metal nitride film contains Ti.   The method of manufacturing a semiconductor device according to any one of claims 18 to 21, wherein the second conductive film formed in the step (d) contains W.

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