JP2006059982A - Semiconductor device and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device and a manufacturing method for the same which semiconductor device has contacts offering advantages of low resistance and high reliability that make the device highly reliable and capable of high-speed transmission. <P>SOLUTION: According to the semiconductor device, a tungsten nitride 24 is formed on the surfaces of the contacts 20, 23, using a CVD method, where the contact surfaces are in contact with silicide films 19, 22, a silicon nitride film 15a, and the inner wall of a first inter-layer insulating film 15b, and the tungsten nitride 24 has such a composition gradient that a nitrogen content decreases with an increasing distance from the surface to the contact interior. Inside the tungsten nitride 24, a tungsten 25 filled with tungsten is formed. As a result, the interface between the tungsten nitride 24 and the tungsten 25 is free from oxidation and pollution. <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 semiconductor device including a contact that contacts an impurity diffusion region and a gate electrode of a silicon substrate.

  2. Description of the Related Art Semiconductor devices have been improved in the degree of integration and downsizing of LSI chips in order to increase the functionality, storage capacity, and power consumption of MOS type LSI chips. The miniaturization of the circuit has a gate length of less than 100 nm, and the technical difficulty becomes higher. The miniaturization of the circuit requires the innovation of the conventional technology.

  In the vertical wiring that electrically connects the impurity diffusion region formed on the silicon substrate and the wiring, for example, the contact, conventionally, the contact resistance with the silicide formed on the surface of the impurity diffusion region is stabilized, and the silicide material In order to suppress reaction and diffusion, a titanium film and a titanium nitride film were sequentially formed by a sputtering apparatus as a barrier film. In addition, when the contact is narrowed by circuit miniaturization and the aspect ratio (= contact hole depth / contact hole width) is large, a titanium film is formed by a sputtering apparatus, and the titanium nitride film is formed of an organic metal (MO ) It was formed by a CVD apparatus. Then, after the bottom surface and the side wall surface of the contact hole are covered with the barrier film, the buried layer is formed of a tungsten material using a CVD apparatus.

  Further, a contact is proposed in which a tungsten nitride film is formed by sputtering as a barrier film that also serves as an adhesion film, and then a buried layer is formed by using a tungsten material by a CVD apparatus (see, for example, Patent Document 1 or 2). .

Thus, in the process of forming the conductive material for the contact, different film forming apparatuses such as a sputtering apparatus and a CVD apparatus, or an MOCVD apparatus and a CVD apparatus are used.
JP-A-8-45878 JP 11-214650 A

  However, if the barrier film and the buried layer are formed using different devices in the formation of the contact, the barrier film will come into contact with the atmosphere and surface oxidation, surface contamination, etc. will occur, increasing the electrical resistance of the contact and distributing the electrical resistance within the contact. And reliability may be reduced. In particular, as the contact rules become narrower and the transmission speed increases as the wiring rules become smaller, these problems become more prominent. In addition, the time from the end of the formation of the barrier film to the start of the formation of the buried layer cannot be shortened, and furthermore, the time varies from wafer to wafer, so the degree of surface oxidation and surface contamination varies from wafer to wafer, Increased product quality variation.

  Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a highly reliable semiconductor device capable of high-speed transmission with a contact capable of reducing electrical resistance and increasing reliability. And a method of manufacturing the same.

  According to one aspect of the present invention, a first conductor, an insulating film covering the first conductor, a second conductor disposed on the insulating film, and the insulating film are penetrated. A contact for electrically connecting the first conductor and the second conductor, and the contact includes a tungsten nitride portion formed on a surface in contact with the first conductor and the insulating film; Provided is a semiconductor device comprising a tungsten portion formed inside the tungsten nitride portion, wherein the nitrogen content decreases almost continuously from the surface of the tungsten nitride portion to the tungsten portion as the distance from the surface increases. Is done.

  According to the present invention, the contact includes a tungsten nitride portion having a composition gradient in which the nitrogen content decreases substantially continuously on the surface of the contact and a tungsten portion continuously formed on the inside thereof. The composition does not change abruptly at the interface between the tungsten nitride portion and the tungsten portion, compared to the case where the film is a tungsten nitride film and the buried layer is tungsten. Therefore, accumulation of internal stress is reduced at the interface, and a dense contact with few internal defects is formed. In addition, oxygen and organic gas are not present at the interface. Therefore, it is possible to realize a contact with low electrical resistance and high reliability, and as a result, it is possible to suppress a signal delay due to an increase in CR (capacitance resistance product) and to realize a highly reliable semiconductor device capable of high-speed transmission.

  According to another aspect of the present invention, a first conductor, an insulating film covering the first conductor, a second conductor provided on the insulating film, and the insulating film are penetrated. A contact for electrically connecting the first conductor and the second conductor, and the contact includes a tungsten nitride portion formed on a surface in contact with the first conductor and the insulating film; There is provided a semiconductor device comprising a tungsten portion formed inside the tungsten nitride portion, wherein a tungsten nitride material and a tungsten material are mixed at the interface between the tungsten nitride portion and the tungsten portion.

  According to the present invention, the tungsten nitride portion is formed on the surface of the contact, and the tungsten portion is continuously formed on the inside thereof, whereby the interface between the tungsten nitride portion and the tungsten portion is mixed with each other. The slope at which the nitrogen content changes at the interface is reduced compared to the case where the conventional barrier film and the buried layer are formed by different apparatuses, and it is assumed that the tungsten nitride portion and the tungsten portion are closely bonded. . Therefore, the local disconnection in the contact due to the thermal history can be avoided, and the electric resistance can be reduced as compared with the conventional case.

  According to another aspect of the present invention, the first conductor, the insulating film covering the first conductor, the second conductor provided on the insulating film, and the insulating film are penetrated. And a contact for electrically connecting the first conductor and the second conductor, wherein the contact hole penetrates the insulating film and exposes the first conductor. Forming a tungsten nitride portion covering the surfaces of the first conductor and the inner wall of the contact hole using a CVD apparatus, and a contact forming step of successively performing a process of filling the tungsten material , A method for manufacturing a semiconductor device is provided.

  According to the present invention, since the contact is formed by continuously performing the process of forming the tungsten nitride portion and the process of filling the contact hole with the tungsten material, the tungsten filled with the tungsten nitride film and the tungsten material. The interface of the part is not contaminated by surface oxidation or organic gas. Therefore, the contact can be made to have lower electrical resistance and higher reliability than a contact in which a barrier film and a buried layer are formed by a different device.

  According to the present invention, it is possible to provide a highly reliable semiconductor device and a method for manufacturing the same, which are provided with a contact capable of reducing electrical resistance and increasing reliability, enabling high-speed transmission.

  Embodiments will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view of a semiconductor device according to the first embodiment of the present invention. Referring to FIG. 1, a semiconductor device 10 includes a silicon substrate 11, a transistor 14 formed in an element region 13 defined on the silicon substrate 11 by an element isolation region 12, a surface of the silicon substrate 11, and a transistor 14. The silicon nitride film 15a and the first interlayer insulating film 15b covering the silicon nitride film 15a, the first interlayer insulating film 15b and the silicon nitride film 15a are in contact with the silicide film 19 formed in the impurity diffusion region 18, and the via 16 and the wiring 17 The contact 20 is electrically connected to the silicide film 22 of the gate electrode 21, and the contact 23 is electrically connected to the via 16 and the wiring 17. Here, an n-type MOS transistor will be described as an example.

  The semiconductor device 10 of this embodiment is mainly characterized in the structure of the contacts 20 and 23 that are electrically connected to the impurity diffusion region 18 and the gate electrode 21. The contacts 20 and 23 have a tungsten nitride portion 24 having a composition gradient formed on the surfaces thereof, that is, the surfaces in contact with the silicide films 19 and 22 and the inner walls of the silicon nitride film 15a and the first interlayer insulating film 15b. Is formed of a tungsten portion 25 filled with tungsten. Next, the contacts 20 and 23 will be described in detail.

  FIG. 2 is an enlarged schematic view showing the main part of the contact. Referring to FIG. 2, the contacts 20 and 23 have a film-like tungsten nitride portion 24 formed on the surfaces in contact with the inner walls of the silicide films 19 and 22, the silicon nitride film 15a and the first interlayer insulating film 15b. As an example, the tungsten nitride portion 24 includes a first tungsten nitride portion 24a to a third tungsten nitride portion 24c in order from the surface.

  The first tungsten nitride portion 24a has a stoichiometric composition of, for example, tungsten nitride, and the second tungsten nitride portion 24b inside has a composition having a lower nitrogen content than the first tungsten nitride portion 24a, Further, the third tungsten nitride portion 24c inside has a composition with a lower nitrogen content than the second tungsten nitride portion 24b. That is, the nitrogen content of the first tungsten nitride portion 24a on the contact surface side is high, the nitrogen content decreases as it goes inside, and the nitrogen content of the third tungsten nitride portion 24c becomes the lowest. A tungsten portion 25 not containing nitrogen is formed inside the third tungsten nitride portion 24c.

  With this configuration, the first tungsten nitride portion 24a on the surface functions as an adhesion film and a barrier layer, and the second tungsten nitride portion 24b, the third tungsten nitride ten portion 24c, the tungsten portion 25, and the nitrogen content By gradually reducing the contact resistance, the contact resistance at each interface can be reduced, and the electrical resistance of the entire contacts 20 and 23 can be reduced.

  Although the first tungsten nitride portion 24a to the third tungsten nitride portion 24c and the tungsten portion 25 are shown to have respective interfaces, the nitrogen content is continuously reduced without having the interfaces. May be. Further, the nitrogen content of the first tungsten nitride portion 24a may be appropriately selected with respect to the stoichiometric composition according to the barrier property.

  FIG. 3 is a diagram showing the composition distribution of the contacts. FIG. 3 shows a contact composition distribution using an EDX (Energy-Dispersive X-ray Spectroscopy) analyzer. For convenience of analysis, a tungsten nitride portion and a tungsten portion are successively formed in this order on the interlayer insulating film formed on the substrate using the same conditions as those for forming contacts (detailed later in the description of the manufacturing method). The sample formed was used. The analysis was performed while etching with Ar ions from the surface side of the tungsten portion of the sample in the direction of the interlayer insulating film. The vertical axis in FIG. 3 indicates the tungsten concentration and the nitrogen concentration, respectively, and the horizontal axis indicates the depth.

  Referring to FIG. 3, from the tungsten portion corresponding to the buried layer having a tungsten concentration of approximately 100 atomic%, the nitrogen concentration gradually increases toward the interlayer insulating film, and the nitrogen concentration is substantially maximum at the interface with the interlayer insulating film. You can see that Therefore, as described above, in the contact, the tungsten nitride portion and the tungsten portion are sequentially formed from the surface in the reverse order, but from the result of FIG. 3, the contact surface (interface with the interlayer insulating film) faces inward. It can be seen that a tungsten nitride portion and a tungsten portion having a composition gradient in which the nitrogen concentration decreases are formed.

  According to the semiconductor device 10 according to the present embodiment, the surfaces of the contacts 20 and 23 are composed of the tungsten nitride portion 24 having a composition gradient, and the tungsten portion 25 is continuously formed on the inside thereof. In addition, since the composition does not change abruptly at the interface between the tungsten nitride portion 24 and the tungsten portion 25 as compared with the case where the barrier film is a tungsten nitride film and the buried layer is a tungsten material, the accumulation of internal stress is small, and the internal Dense contacts 20 and 23 with few defects are formed. Therefore, it is possible to form contacts 20 and 23 with low electrical resistance and high reliability due to their denseness.

  Next, a method for manufacturing the semiconductor device according to the first embodiment will be described with reference to FIGS. 4 to 6 are manufacturing process diagrams of the semiconductor device according to the first embodiment.

  First, in the process of FIG. 4A, the element isolation region 12 is formed on the silicon substrate 11 by the STI method. The silicon substrate 11 may be a bulk substrate or an SOI substrate (Silicon On Insulating substrate).

In the step of FIG. 4A, p-type impurity ions such as B ⁺ and BF ₂ ⁺ are implanted into the element region 13 by ion implantation to form the p-type well region 26.

In the step of FIG. 4A, a gate laminated body 29 including a gate oxide film 28 and a polysilicon film gate electrode 21 is further formed on the surface of the silicon substrate 11. Specifically, the gate oxide film 28 is formed by removing a silicon natural oxide film (not shown) on the surface of the silicon substrate 11 by HF treatment, and forming the surface of the silicon substrate 11 by CVD, sputtering, or thermal oxidation treatment. For example, a silicon oxide film 28a having a thickness of 3 nm is formed. In place of the silicon oxide film 28a, a silicon oxynitride film or a silicon nitride film may be used, and a laminate of these films and a silicon oxide film may be used. As the polysilicon film 21a, a non-doped polysilicon film is formed on the silicon oxide film 28a by the CVD method. A doped polysilicon film doped with P ⁺ or B ⁺ may be formed by mixing PH ₃ gas or the like. Next, a resist film (not shown) is formed and patterned on the polysilicon film 21a, and the polysilicon film 21a and the silicon oxide film 28a are etched by the RIE method using the resist film as a mask to obtain the gate insulating film 28 and the gate electrode. A gate stack 29 made of 21 is formed.

Further, in the step of FIG. 4A, using the gate stacked body 29 as a mask, B ⁺ (for example, implantation energy 10 keV, dose amount 1 × 10 ¹³ cm ⁻² ) is set at an incident angle of 35 degrees, for example, and implantation is performed. A p-type pocket region 30 is formed in the silicon substrate 11 on both sides of the body 29.

Further, in the step of FIG. 4A, As ⁺ (implantation energy 1 keV) is implanted almost perpendicularly to the substrate surface using the gate stacked body 29 as a mask, and shallow junction regions 31 are formed on both sides of the gate. Here, the shallow junction region 31 is formed on the upper side of the p-type pocket region 30, that is, on the surface side of the silicon substrate 11.

Next, in the step of FIG. 4B, sidewall insulating films 32 are formed on both sides of the gate stacked body 29. Specifically, the silicon nitride film 23a having a thickness of, for example, 100nm by CVD so as to cover the surface and the gate stack 29 of the silicon substrate 11 is formed, is etched back by RIE using the C _x H _y F _z gas To do.

In the step of FIG. 4B, P ⁺ (for example, implantation energy 6 keV, dose amount 2 × 10 ¹⁵ cm ⁻² ) is implanted almost perpendicularly to the substrate surface using the gate stack 29 and the sidewall insulating film 32 as a mask. Deep junction regions 33 are formed in the device regions 13 on both sides of the sidewall insulating film 32. An activation heat treatment is performed on the impurity region 18 including the shallow junction region 31 and the deep junction region 33.

Next, in the step of FIG. 4C, for example, a Ni film 34 that covers the structure of FIG. 4B is formed by sputtering. Next, heat treatment (temperature 400 ° C. to 500 ° C.) is performed using an RTP (Rapid Thermal Process) apparatus, the Ni film is reacted with silicon of the silicon substrate and the gate electrode, and a silicide film 19 of a NiSi film (for example, a film thickness of 20 nm), 22 is formed on the surfaces of the impurity diffusion region 18 and the gate electrode 21. Next, the unreacted Ni film 34 is removed by wet etching (primary treatment) with a mixture of ammonia and hydrogen peroxide, and further wet etching (secondary treatment) with a mixture of sulfuric acid and hydrogen peroxide. Next, heat treatment (temperature: 400 ° C. to 500 ° C.) is performed using an RTP apparatus. The NiSi film is preferable in that the heating temperature (400 ° C. to 500 ° C.) for heat treatment is low. In addition to the NiSi film, a CoSi ₂ film, a TaSi ₂ film, a TiSi ₂ film, or a PtSi film may be formed. For example, in the case of a CoSi ₂ film, the heating temperature for heat treatment is set to 500 ° C. to 700 ° C.

  Next, in the step of FIG. 5A, a silicon nitride film 15a and a first interlayer insulating film 15b that cover the structure of FIG. Specifically, the silicon nitride film 15a is formed to a thickness of 80 nm by, for example, a CVD method, and the first interlayer insulating film 15b is, for example, a silicon oxide film by a sputtering method, or a TEOS (tetraethoxysilane) gas by a CVD method. A silicon oxide film using BPSG, a BPSG (Boro-Phospho Silicate Glass) film, a SIOC (siloxane alkoxy-based) film, or the like can be used. Note that a siloxane-based inorganic or organic SOD (Spin On Dielectric) or a low-k film of an organic material such as polyallyl ether may be used for the first interlayer insulating film 15b.

  In the step of FIG. 5A, the surface of the first interlayer insulating film 15b is further planarized by the CMP method.

  5B, a resist film 38 is formed on the first interlayer insulating film 15b, and an opening 38a having a contact hole pattern is formed by photolithography.

6A, the first interlayer insulating film 15b is etched by the RIE method using the resist film 38 as a mask. When the first interlayer insulating film 15b is a silicon oxide film, etching is performed using a mixed gas of CF ₄ and H _{2 as} an etching gas, and the etching stops on the surface of the silicon nitride film 15a.

FIG 6 (A) further includes the step, contacts the etching gas with C _x H _y F _z gas, a silicon nitride film 15a through to expose the silicide film 19, 22 on the surface of the silicon substrate 11 and the gate electrode 21 Hole 20a is formed.

In the step of FIG. 6A, the resist film 39 is further removed by a wet method, and then the surfaces of the silicide films 19 and 22 are etched using a plasma etching apparatus using NF ₃ gas or H ₂ gas. And clean. Resist residues and silicon oxide film residues may remain at the bottoms of the contact holes 20a and 23a. By cleaning, the reliability of contact between the silicide films 19 and 22 and the contact formed in the next step can be improved. In particular, it is effective when the aspect ratio of the contact holes 20a and 23a is large. Specifically, for example, the pressure is set to 200 Pa, the RF output is 500 W, and the processing time is 30 seconds using NF ₃ gas.

Further, instead of cleaning with NF ₃ gas or H ₂ gas, the surface of the silicide films 20a and 23a may be cleaned by sputtering with Ar gas using a sputtering apparatus. Ar gas sputter etching is preferable because of its high ability to remove the residue.

6B, a conductive material composed of a tungsten nitride portion and a tungsten portion having a composition gradient is continuously formed in the contact holes 20a and 23a by a CVD method. Specifically, the substrate is heated, and at the start of film formation, tungsten hexafluoride (WF ₆ ), silane (SiH ₄ ), ammonia (NH ₃ ), and hydrogen (H) are used as process gases in the container of the CVD apparatus. ₂ ) Supply a gas to form a tungsten nitride film. Then, the NH ₃ gas flow rate is gradually decreased, and finally the NH ₃ gas flow rate is set to 0, and WF ₆ gas, SiH ₄ gas, and H ₂ gas are supplied. As a result, a tungsten nitride portion 24 having a composition gradient in which the nitrogen content gradually decreases toward the inside is formed on the surface, and a tungsten portion 25 made of tungsten is formed on the inside. In this way, contacts 20 and 23 having the structure shown in FIG. 2 are formed.

More specifically, at the start of film formation, the substrate is heated to 200 ° C. to 400 ° C., and the inside of the container of the CVD apparatus is, for example, pressure 200 Pa, WF ₆ gas flow rate 80 sccm, SiH ₄ gas flow rate 5 sccm, NH ₃ gas flow rate. 160 sccm and Ar gas flow rate 5000 sccm. Then, the NH ₃ gas flow rate is decreased, for example, at a rate of ₃ sccm / second or stepwise. Finally, the NH ₃ gas flow rate is set to 0, the pressure is 1000 Pa, the WF ₆ gas flow rate is 80 sccm, and the H ₂ gas flow rate is 5000 sccm. To do. By forming the film in this manner, the nitrogen content continuously decreases as the nitrogen content moves away from the outer surfaces of the contacts 20 and 23 as shown in FIG. , 23 are formed. B ₂ H ₆ gas may be used instead of SiH ₄ gas.

  The tungsten nitride portion 24 having a composition gradient is preferably formed to a thickness of 1 nm to 0 nm from the contact surface. When the thickness of the tungsten nitride portion 24 exceeds 20% of the radius when the cross-sectional shape parallel to the substrate surface of the contact hole is circular, when the cross-sectional shape parallel to the substrate surface of the contact hole is square, When it exceeds 10% of the length of one side, its own electrical resistance increases, and the electrical resistance of the entire contact increases. When the thickness is less than 1 nm, the function as a barrier film is lowered, and the diffusion of silicon atoms from the silicide film to the contact is increased. Here, the thickness means a thickness at which the nitrogen content is almost zero from the contact surface.

  6B, the surface of the conductive material 40 is planarized by CMP (Chemical Mechanical Polishing) until the surface of the first interlayer insulating film 15b is exposed. Thereafter, although illustration and detailed description are omitted, referring to FIG. 1, further, a second interlayer insulating film 36, an etching stopper film 35a, and a third interlayer covering the first interlayer insulating film and the contacts 20, 23. An insulating film 37 and an etching / stopper film 35b are sequentially formed, and vias 16 and wirings 17 made of Cu that are in contact with the surfaces of the contacts 20 and 23 are formed by using a dual damascene method. The semiconductor device 10 shown in FIG. It is formed.

  According to the present embodiment, the tungsten nitride portion 24 as the adhesion film and the barrier film is formed on the surfaces of the contacts 20 and 23 by using the CVD method, and the tungsten portion 25 as the buried layer is continuously formed on the inside thereof. By forming, the tungsten nitride part 24 is not exposed to the atmosphere. Conventionally, when the barrier film and the buried layer are formed by different apparatuses, the barrier film is oxidized or contaminated, causing electrical resistance or disconnection of the contact. Accordingly, the surface oxidation or surface contamination of the barrier film can be prevented, and a highly reliable contact can be formed with low electrical resistance.

  In addition, according to the present embodiment, since the barrier film and the buried layer are integrally formed, a portion having a high nitrogen content in the tungsten nitride portion 24 having a composition gradient, for example, a difference first tungsten nitride. Since the thickness of the portion 24a can be reduced, the electrical resistance of the contacts 20, 23 can be reduced.

  The tungsten portion 25 may contain at least one element of Si, B, P, and Ti with tungsten as a main component.

(Second Embodiment)
FIG. 7 is a cross-sectional view of a semiconductor device according to the second embodiment of the present invention, and FIG. 8 is a schematic diagram showing an enlarged main part of a contact of the semiconductor device according to the second embodiment. In the figure, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof is omitted.

  7 and 8, the semiconductor device 60 according to the present embodiment is configured in the same manner as the semiconductor device according to the first embodiment, except that the structures of the contacts 61 and 62 are different.

  In the contacts 61 and 62, a tungsten nitride film 63 is formed on the surface in contact with the inner walls of the silicide films 19 and 22 and the first interlayer insulating film 15b, and a tungsten portion filled with tungsten is formed inside thereof. The tungsten nitride film 63 is made of tungsten nitride having a stoichiometric composition, for example. 7 and 8 show the interface between the tungsten nitride film and the tungsten material. Since the tungsten nitride film 63 and the tungsten portion 25 are formed continuously, tungsten nitride and tungsten are mixed at the interface. The interface is blurred. Therefore, the slope at which the nitrogen content changes at the interface is reduced as compared with the case where the conventional barrier film and the buried layer are formed by different devices, and the tungsten nitride film 63 and the tungsten portion 25 are closely bonded. It is guessed. Therefore, the local disconnection in the contact due to the thermal history can be avoided, and the electric resistance can be reduced as compared with the conventional case.

The contacts 61 and 62 are formed in the step of FIG. 6B of the first embodiment by heating the substrate to 200 ° C. to 400 ° C. in the CVD apparatus container at the start of film formation by the CVD method. WF ₆ gas, SiH ₄ gas, NH ₃ gas, and Ar gas are supplied as process gases to form a tungsten nitride film 63. Then, the supply of NH ₃ gas and Ar gas is stopped, and WF ₆ gas, SiH ₄ gas, and H ₂ gas are supplied to form the tungsten portion 25. Specific manufacturing conditions are substantially the same as the above-described process of FIG. By forming the film in this way, the surface of the tungsten nitride film 63 can be continuously formed without being exposed to the atmosphere. B ₂ H ₆ gas may be used instead of SiH ₄ gas.

  According to the present embodiment, since the interface between the tungsten nitride film 63 and the tungsten portion 25 is not exposed to the atmosphere, the contacts 61 and 62 are free from oxygen atoms and organic gases contained in the atmosphere and oxidized. There is no pollution. Therefore, the contacts 61 and 62 are formed by a device in which the conventional barrier film and the buried layer are different from each other, and have lower electrical resistance and higher reliability than when exposed to the atmosphere between the barrier film and the buried layer. Can be achieved.

  Next, a semiconductor device according to a modification of the present embodiment will be described. Since the semiconductor device of this modification is configured in the same manner as the semiconductor device shown in FIG. 7 except that the contact structure is different, the description of the same parts is omitted.

  FIG. 9 is an enlarged schematic view showing the main part of the contact of the semiconductor device according to the modification of the second embodiment. In the figure, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof is omitted.

  The contacts 60 and 61 of this modification have a tungsten film 65 formed on the surface thereof, that is, the surface in contact with the inner walls of the silicide films 19 and 22 and the first interlayer insulating film 15b, and the tungsten nitride film 63 and the inner side thereof. Except for the tungsten portion 25 filled with tungsten inside and the tungsten film 65 provided, the contact portion is configured in the same manner as the contact of the second embodiment shown in FIGS.

The tungsten film 65 includes, for example, about 1 to 5 atomic layers, and is formed using a CVD method, particularly an ALD (Atomic Layer Deposition) method capable of forming a monoatomic layer. The contact holes 20a and 23a are filled with a conductive material by using the ALD method instead of the CVD method in the step of FIG. 6B described above. Specifically, first, SiH ₄ gas is supplied to form an initiation film on the surfaces of the contact holes 20a and 23a, and then WF ₆ gas (for example, flow rate 50 sccm) and NH ₃ gas (for example, flow rate 100 sccm) are alternately used. By supplying repeatedly 10 to 60 times, a tungsten film 65 and a tungsten nitride film 63 are formed, and further, a tungsten portion 25 is formed inside thereof as in the first embodiment. Since other steps are the same as those in the first embodiment described above, description thereof is omitted.

  According to this modification, since the surfaces of the contacts 60 and 61 that are in contact with the silicide films 19 and 22 are made of the tungsten film 65, the adhesion is good and the contact resistance between the silicide films 19 and 22 and the contacts 60 and 61 is reduced. Can be reduced.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the present invention described in the claims. It can be changed.

  For example, in the embodiment, the case where the contact is in contact with the impurity diffusion region or the silicide film formed in the gate electrode has been described as an example. However, the contact can be applied to a vertical wiring such as a via or a plug.

  In the embodiment, the n-type MOS transistor is described as an example. However, the present invention can be applied to a p-type MOS transistor, a CMOS transistor, a MIS (Metal Insulator Semiconductor) transistor, and other semiconductor devices.

In addition to the above description, the following additional notes are disclosed.
(Appendix 1) a first conductor;
An insulating film covering the first conductor;
A second conductor disposed on the insulating film;
A contact penetrating the insulating film and electrically connecting the first conductor and the second conductor;
The contact is
A tungsten nitride portion formed on a surface in contact with the first conductor and the insulating film, and a tungsten portion formed inside the tungsten nitride portion,
A semiconductor device characterized in that the nitrogen content decreases substantially continuously from the surface of the tungsten nitride portion to the tungsten portion as the distance from the surface increases.
(Supplementary note 2) The semiconductor device according to supplementary note 1, wherein the contact further includes a tungsten film outside the tungsten nitride portion.
(Supplementary note 3) The semiconductor device according to supplementary note 2, wherein the tungsten film includes any number of atomic layers of one atomic layer to five atomic layers.
(Appendix 4) A silicon substrate,
A transistor comprising an impurity diffusion region formed in the silicon substrate, and a gate structure having a gate oxide film and a gate electrode;
A silicide film formed on the surface of the impurity diffusion region or gate electrode;
An insulating film covering the surface of the silicon substrate and the transistor;
Wiring formed on the insulating film;
A contact penetrating the insulating film and electrically connecting the silicide film and the wiring,
The contact is
The tungsten nitride portion formed on the surface in contact with the silicide film and the insulating film, and a tungsten portion formed inside the tungsten nitride portion,
A semiconductor device characterized in that the nitrogen content decreases substantially continuously from the surface of the tungsten nitride portion to the tungsten portion as the distance from the surface increases.
(Supplementary Note 5) a first conductor;
An insulating film covering the first conductor;
A second conductor provided on the insulating film;
A contact penetrating the insulating film and electrically connecting the first conductor and the second conductor;
The contact is
A tungsten nitride portion formed on a surface in contact with the first conductor and the insulating film, and a tungsten portion formed inside the tungsten nitride portion,
A semiconductor device comprising a mixture of a tungsten nitride material and a tungsten material at an interface between the tungsten nitride portion and the tungsten portion.
(Appendix 6) The first conductor is made of a silicide film,
6. The semiconductor device according to claim 1, wherein the silicide film is made of one of a group consisting of NiSi, CoSi ₂ , TaSi ₂ , TiSi ₂ , and PtSi.
(Supplementary note 7) The supplementary notes 1-3, 5, and 6, wherein the second conductor has a surface in contact with an insulating film made of the tungsten nitride portion, and the tungsten portion is formed on the inside thereof. The semiconductor device as described in any one of these.
(Appendix 8) a first conductor;
An insulating film covering the first conductor;
A second conductor provided on the insulating film;
A method of manufacturing a semiconductor device comprising: a contact penetrating the insulating film and electrically connecting the first conductor and the second conductor;
Forming a contact hole penetrating the insulating film and exposing the first conductor;
A contact forming step of continuously performing a process of forming a tungsten nitride portion covering the surfaces of the first conductor and the inner wall of the contact hole, and then a process of filling the contact hole with a tungsten material using a CVD apparatus; A method for manufacturing a semiconductor device, comprising:
The process gas used in the process of forming a (Supplementary Note 9) The tungsten nitride portion, WF ₆ gas, and NH ₃ gas, and Ar gas, a SiH ₄ gas or B ₂ H ₆ gas,
The method of manufacturing a semiconductor device according to appendix 8, wherein a process gas used for the process of forming the tungsten material portion is WF ₆ gas, H ₂ gas, SiH ₄ gas, or B ₂ H ₆ gas.
(Additional remark 10) The process which fills the said tungsten material stops supply of the process gas used as the nitrogen source used for the process which forms a tungsten nitride part, and is continuously filled with a tungsten material characterized by the above-mentioned. Or a method of manufacturing a semiconductor device according to 9.
(Supplementary Note 11) In the process of forming the tungsten nitride portion, the flow rate of the process gas serving as the nitrogen source is set to the first flow rate at the start of film formation, and then the flow rate is gradually decreased. The method of manufacturing a semiconductor device according to any one of appendices 8 to 10, wherein the second flow rate is set to be smaller than the flow rate of the above.
(Supplementary note 12) The semiconductor device manufacturing method according to supplementary note 11, wherein the flow rate is decreased stepwise or continuously from the first flow rate to the second flow rate.
(Additional remark 13) The manufacturing method of the semiconductor device of Additional remark 11 or 12 characterized by making said 2nd flow volume into substantially zero.
(Supplementary Note 14) Between the step of forming a contact hole and the step of forming a contact,
Of the supplementary notes 8 to 13, wherein the surface of the first conductor is subjected to plasma etching using NF ₃ gas or H ₂ gas, or sputter etching is performed using Ar gas. A manufacturing method of a semiconductor device given in any 1 paragraph.

1 is a cross-sectional view of a semiconductor device according to a first embodiment of the present invention. It is a schematic diagram which expands and shows the principal part of the contact of the semiconductor device which concerns on 1st Embodiment. It is a figure which shows the composition distribution of a contact. FIGS. 6A to 6C are manufacturing process diagrams (part 1) of the semiconductor device according to the first embodiment; FIGS. (A) And (B) is a manufacturing process figure (the 2) of a semiconductor device concerning a 1st embodiment. (A) And (B) is a manufacturing process figure (the 3) of a semiconductor device concerning a 1st embodiment. It is sectional drawing of the semiconductor device which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which expands and shows the principal part of the contact of the semiconductor device which concerns on 2nd Embodiment. It is a schematic diagram which expands and shows the principal part of the contact of the semiconductor device which concerns on the modification of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor device 11 Silicon substrate 12 Element isolation region 13 Element region 14 Transistor 15a Silicon nitride film 15b First interlayer insulating film 16 Via 17 Wiring 18 Impurity diffusion region 19, 22 Silicide film 20, 23, 61, 62 Contact 21 Gate electrode 21a Polysilicon film 24 Tungsten nitride part 24a-24c First to third tungsten nitride part 25 Tungsten part 26 P-type well region 28 Gate oxide film 29 Gate stack 30 P-type pocket region 31 Shallow junction region 32 Side wall insulating film 33 Deep junction Region 34 Ni film 35a, 35b Etching / stopper film 36 Second interlayer insulating film 37 Third interlayer insulating film 38, 39 Resist film 40 Conductive material 63 Tungsten nitride film 65 Tungsten film

Claims (5)

A first conductor;
An insulating film covering the first conductor;
A second conductor disposed on the insulating film;
A contact penetrating the insulating film and electrically connecting the first conductor and the second conductor;
The contact is
A tungsten nitride portion formed on a surface in contact with the first conductor and the insulating film, and a tungsten portion formed inside the tungsten nitride portion,
A semiconductor device characterized in that the nitrogen content decreases substantially continuously from the surface of the tungsten nitride portion to the tungsten portion as the distance from the surface increases. A first conductor;
An insulating film covering the first conductor;
A second conductor provided on the insulating film;
A contact penetrating the insulating film and electrically connecting the first conductor and the second conductor;
The contact is
A tungsten nitride portion formed on a surface in contact with the first conductor and the insulating film, and a tungsten portion formed inside the tungsten nitride portion,
A semiconductor device comprising a mixture of a tungsten nitride material and a tungsten material at an interface between the tungsten nitride portion and the tungsten portion. A first conductor;
An insulating film covering the first conductor;
A second conductor provided on the insulating film;
A method of manufacturing a semiconductor device comprising: a contact penetrating the insulating film and electrically connecting the first conductor and the second conductor;
Forming a contact hole penetrating the insulating film and exposing the first conductor;
And a contact forming step of continuously performing a process of forming a tungsten nitride portion covering the surfaces of the first conductor and the inner wall of the contact hole and a process of filling with a tungsten material using a CVD apparatus. A method for manufacturing a semiconductor device.   4. The method of manufacturing a semiconductor device according to claim 3, wherein in the process of filling the tungsten material, the supply of a process gas serving as a nitrogen source used for the process of forming the tungsten nitride portion is stopped and the tungsten material is filled. Method. In the process of forming the tungsten nitride film, the flow rate of the process gas serving as a nitrogen source is set to the first flow rate at the start of film formation, and then gradually decreased, and at the end of the film formation, the flow rate is higher than the first flow rate. 5. The method of manufacturing a semiconductor device according to claim 3, wherein the second flow rate is set to be small.

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