JP2013157597A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device having a wiring structure which suppresses an increase in layer resistance and is excellent in stress migration resistance and adhesion to an insulating film.SOLUTION: An intermediate wiring layer 221 of a semiconductor device 200 is formed by: providing a metal layer 235 on a barrier layer 231; providing a first nitrogen-containing film 237 on the metal layer 235; and providing a second nitrogen-containing film 239 on the first nitrogen-containing film 237. The nitrogen content of the first nitrogen-containing film 237 is lower than that of the second nitrogen-containing film 239.

Description

  The present invention relates to a wiring structure in an electronic device such as a semiconductor device, and more particularly to a method of manufacturing a semiconductor device having a wiring structure that improves stress migration resistance of Al wiring and has low resistance.

  In recent years, semiconductor integrated circuit devices, particularly LSIs, have been miniaturized.

  As the components become finer, the cross-sectional area of the metal wiring that is the conductive layer decreases, and stress relaxation occurs due to the difference in thermal expansion coefficient between the insulating film and the metal wiring. When stress relaxation occurs, stress migration in which metal atoms in the metal wiring move and voids are formed becomes a problem.

  In addition, when a titanium nitride film is used as the insulating film and an Al film is used as the conductive layer, if the titanium nitride film is in direct contact with the Al film, nitrogen atoms diffuse from the titanium nitride film to the Al film due to heat treatment after the wiring is formed. It has been found that when a large amount of nitrogen atoms are present in the Al film, the stress migration resistance of the Al film deteriorates (Patent Document 1, Non-Patent Document 1).

  For this reason, by disposing the titanium film between the Al film and the titanium nitride film, the titanium nitride film and the Al film are prevented from coming into direct contact, and the nitrogen in the titanium nitride film does not diffuse into the Al film, and stress A structure capable of preventing migration degradation has been proposed (Patent Document 1).

  Patent Document 2 discloses a titanium nitride system composed of a plurality of types of films having different compositions so as to continuously change from TiN to TiNx (x is 0 <x <1) on the metal wiring film. An antireflection film and a semiconductor device having an interlayer insulating film on the antireflection film are disclosed.

JP-A-11-186263 Japanese Patent Laid-Open No. 11-016910

Jon Klema et.al., Proceedings of 1984 Reliability Physics Simposium, p1,1984

  However, the manufacturing method described in Patent Document 1 has a problem in that an AlTi compound is generated in the Al film by the heat treatment after the wiring is formed, and the layer resistance of the Al film as the wiring layer is increased.

  Further, in the structure of Patent Document 2, since the adhesion between TiN and the interlayer insulating film is worse than the adhesion between Ti and the interlayer insulating film, for example, when a through hole is formed in the interlayer insulating film, the interlayer insulation There was a problem that the film peeled off from TiN, and the through-hole embedding material entered the peeled portion and caused a short circuit with the adjacent wiring.

  Therefore, there has been a demand for a method of manufacturing a semiconductor device having a wiring structure that suppresses an increase in layer resistance and has excellent stress migration resistance and adhesion to an insulating film.

  According to a first aspect of the present invention, (a) a first nitrogen-containing film is formed on a metal layer by first reactive sputtering, and (b) a second nitrogen-containing film is formed on the first nitrogen-containing film. The first nitrogen-containing film has a nitrogen content lower than that of the second nitrogen-containing film.

  In the second aspect of the present invention, (d) a first nitrogen-containing film and a second nitrogen-containing film are sequentially formed on a metal layer using a titanium target in an atmosphere containing an inert gas and a nitrogen gas. (D) is a flow rate ratio of the nitrogen gas to a total flow rate that is a sum of the flow rate of the inert gas and the flow rate of the nitrogen gas when the first nitrogen-containing film is formed. It is a manufacturing method of a semiconductor device lower than a flow rate ratio at the time of forming the second nitrogen content film.

  In the third aspect of the present invention, (f) a barrier film is formed on the substrate, (g) a metal layer is formed on the barrier film, and (h) a first nitrogen-containing film is formed on the metal layer. (I) forming a second nitrogen-containing film having a nitrogen content higher than that of the first nitrogen-containing film on the first nitrogen-containing film, and (j) containing the second nitrogen on the second nitrogen-containing film. Forming a third nitrogen-containing film having a nitrogen content lower than that of the film; (k) patterning the third, second and first nitrogen-containing films, the metal layer and the barrier film into a wiring having a desired shape; (L) forming an interlayer insulating film covering the wiring, and (m) providing an opening in the interlayer insulating film so that a part of the third nitrogen-containing film is exposed. .

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the semiconductor device which has the wiring structure which suppressed the raise of layer resistance and was excellent in stress migration and the adhesiveness with an insulating film can be provided.

2 is a cross-sectional view showing a wiring structure 100. FIG. It is a flowchart which shows the outline of the manufacturing process of the wiring structure 100 which concerns on 1st Embodiment. It is a flowchart which shows the detail of the manufacturing process of the wiring structure 100 which concerns on 1st Embodiment. It is a flowchart which shows the detail of the manufacturing process of the wiring structure 100 which concerns on 2nd Embodiment. Nitrogen flow ratio _{(N 2} flow rate / (Ar flow rate + _{N 2} flow rate)) and a diagram showing the relationship between the deposition rate. It is a figure which shows the relationship between a nitrogen flow rate and a deposition. It is a figure which shows the relationship between Ti film thickness on Al layer, and wiring layer resistance. It is sectional drawing which shows the semiconductor device 200 which concerns on 3rd Embodiment. It is a flowchart which shows the outline of the manufacturing process of the semiconductor device 200 which concerns on 3rd Embodiment. It is sectional drawing which shows the manufacturing process of the semiconductor device 200 concerning 3rd Embodiment. It is sectional drawing which shows the manufacturing process of the semiconductor device 200 concerning 3rd Embodiment. It is sectional drawing which shows the manufacturing process of the semiconductor device 200 concerning 3rd Embodiment. It is sectional drawing which shows the manufacturing process of the semiconductor device 200 concerning 3rd Embodiment. It is sectional drawing which shows the semiconductor device 200a which concerns on 4th Embodiment. It is a flowchart which shows the process corresponded to S33 of FIG. 9 among the manufacturing processes of the semiconductor device 200a which concerns on 4th Embodiment. It is sectional drawing which shows the manufacturing process of the semiconductor device 200a which concerns on 4th Embodiment. It is sectional drawing which shows the manufacturing process of the semiconductor device 200a which concerns on 4th Embodiment. It is sectional drawing which shows the semiconductor device 200b which concerns on 5th Embodiment. It is a flowchart which shows the process corresponded to S33 of FIG. 9 among the manufacturing processes of the semiconductor device 200b which concerns on 5th Embodiment. It is sectional drawing which shows the manufacturing process of the semiconductor device 200b which concerns on 5th Embodiment. It is sectional drawing which shows the manufacturing process of the semiconductor device 200b which concerns on 5th Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

  First, the structure of a wiring structure 100 manufactured by the method for manufacturing a wiring structure according to the first embodiment of the present invention will be described with reference to FIG.

Here, a wiring structure of a semiconductor device is illustrated as the wiring structure 100.
As shown in FIG. 1, the wiring structure 100 includes a first titanium nitride film 11 provided on a substrate 10 such as a semiconductor, a conductive film 12 that is a wiring portion provided on the first titanium nitride film 11, and A second titanium nitride film 13 is provided on the conductive film 12.

  The second titanium nitride film 13 is provided on the conductive film 12 (metal film) and is provided on the first sputtering film 14 (first nitrogen-containing film) containing nitrogen and the first sputtering film 14 and contains nitrogen. The second sputtering film 15 (second nitrogen-containing film) is included, and the first sputtering film 14 has a lower nitrogen content than the second sputtering film 15.

  Next, an outline of a method for manufacturing the wiring structure 100 will be described with reference to FIG.

  First, a first titanium nitride film 11 is formed on the substrate 10 (S1 in FIG. 2).

  Next, a film containing Al, for example, a conductor containing AlCu, is formed as the conductive film 12 on the first titanium nitride film 11 by sputtering (S2 in FIG. 2).

  Subsequently, the second titanium nitride film 13 is formed on the conductive film 12 without being exposed to the atmosphere from the state of S2.

  Specifically, the first sputtering film 14 is formed on the conductive film 12 by non-reactive sputtering (reactive sputtering under the first condition) (S3 in FIG. 2), and then reactive sputtering (under the second condition). A second sputtering film 15 is formed on the first sputtering film 14 by reactive sputtering (S4 in FIG. 2).

  Here, the reactive sputtering means a state in which a target surface is nitrided and reacts in a titanium target. At this time, since the target surface is titanium nitride, the deposition rate decreases. In contrast to non-reactive sputtering, the target surface is not sufficiently nitrided, and the titanium deposition becomes dominant and high. It is possible to distinguish reactive and non-reactive by deporate. Here, the relationship between the nitrogen gas flow rate ratio and the deposition rate is disclosed, for example, in JP-A-9-181018, and the reactive sputtering and the non-reactive sputtering can be controlled by the nitrogen gas flow rate ratio. This is shown in FIGS.

  As shown in FIGS. 5 and 6, the relationship between the nitrogen gas flow rate ratio and the deposition rate has a hysteresis relationship in which reactive sputtering causes reactive sputtering and nonreactive sputtering causes nonreactive sputtering.

  That is, when the inert gas flow rate is made constant and the nitrogen gas flow rate is gradually increased from 0, since the sputtering is initially performed at a non-reaction limited rate, the deposition rate gradually decreases. If the nitrogen gas flow rate ratio is further increased, the deposition rate rapidly decreases at a certain flow rate, and reactive sputtering occurs. Thereafter, since the reaction rate is controlled, the deposition rate does not decrease so much even if the flow rate of nitrogen gas is increased. Conversely, when the nitrogen gas flow rate is decreased from reactive sputtering, non-reactive sputtering occurs at a lower flow rate value, which is different from the previous method, and becomes non-reactive. Therefore, based on the relationship shown in FIGS. 5 and 6, reactive sputtering and non-reactive sputtering can be controlled by the nitrogen gas flow rate ratio.

  As described above, when the second titanium nitride film 13 is formed, the non-reactive sputtering and the reactive sputtering are continuously performed, so that the nitrogen content of the first sputtering film 14 is lower than that of the second sputtering film 15. .

  When the nitrogen content of the first sputtering film 14 is lower than that of the second sputtering film 15, the amount of N atoms taken into the conductive film 12 from the second titanium nitride film 13 can be reduced, and the stress migration of the conductive film 12. Resistance can be improved. On the other hand, when a small amount of N atoms are mixed into the conductive film 12 from the first sputtering film 14, generation of an AlTi alloy in the conductive film 12 is inhibited, and an increase in the layer resistance of the conductive film 12 can be prevented.

  Next, details of the method for manufacturing the wiring structure 100 will be described with reference to FIG.

  Here, as an example, a titanium target is used as a target, argon is used as an inert gas, and nitrogen is used as a reactive gas, and the first sputtering film 14 and the second sputtering film 15 are formed in the same chamber. Explained.

  First, the substrate 10 is prepared and placed in the chamber, and the first titanium nitride film 11 is formed on the substrate 10 by reactive sputtering (S11 in FIG. 3).

  Next, an ALCu film is formed as the conductive film 12 on the first titanium nitride film 11 by sputtering (S12 in FIG. 3).

  Next, in order to switch the target to non-reactive sputtering, the substrate 10 is shielded with a shutter or a disk in a state where the flow rate of nitrogen gas is lower than S11, and non-reactive sputtering is performed (S13 in FIG. 3). .

  Next, the shielding of the shutter or the disk is released, and the first sputtering film 14 is formed on the conductive film 12 by non-reactive sputtering (S14 in FIG. 3).

  Next, in order to switch the target to reactive sputtering, the nitrogen gas flow rate ratio is increased from S11, the substrate 10 is shielded by a shutter or a disk, and reactive sputtering is performed (S15 in FIG. 3).

Next, the shielding of the shutter or the disk is released, and the second sputtering film 15 is formed on the first sputtering film 14 by reactive sputtering (S16 in FIG. 3).
The wiring structure 100 is manufactured by the above procedure.

  Thus, according to the first embodiment, in the wiring structure 100, the first sputtering film 14 containing nitrogen is formed on the conductive film 12 by non-reactive sputtering, and the reactive structure is formed on the first sputtering film 14. It is manufactured by forming a second sputtering film 15 containing nitrogen by sputtering, and the first sputtering film 14 has a lower nitrogen content than the second sputtering film 15.

  Therefore, the amount of N atoms taken by the conductive film 12 can be reduced, and the stress migration resistance can be improved.

  In addition, the generation of the AlTi alloy in the conductive film 12 is inhibited, and an increase in the layer resistance of the Al wiring can be prevented.

  Next, a second embodiment will be described with reference to FIG.

  In the second embodiment, the wiring structure 100 is manufactured by using the apparatus having two or more Al chambers and titanium chambers in the multi-chamber sputtering apparatus in the first embodiment.

  In the second embodiment, elements having the same functions as those in the first embodiment are denoted by the same reference numerals, and a manufacturing method that is a different part from the first embodiment will be mainly described.

  First, the substrate 10 is prepared and placed in a titanium chamber for reactive sputtering, and the first titanium nitride film 11 is formed on the substrate 10 by reactive sputtering (S21 in FIG. 4).

  Next, the substrate 10 is placed in the Al chamber, and an AlCu film is formed as the conductive film 12 on the first titanium nitride film 11 by sputtering (S22 in FIG. 3).

  Next, the substrate 10 is placed in a titanium chamber for non-reactive sputtering, and the first sputtering film 14 is formed on the conductive film 12 by non-reactive sputtering (S23 in FIG. 3).

Next, the substrate 10 is placed in a titanium chamber for reactive sputtering, and the second sputtering film 15 is formed on the first sputtering film 14 by reactive sputtering (S24 in FIG. 3).
The wiring structure 100 is manufactured by the above procedure.

  In this way, by using an apparatus having two or more Al chambers and titanium chambers, sputtering in a state where the substrate is shielded by a shutter or a disk for switching between reactive sputtering and non-reactive sputtering becomes unnecessary. High throughput can be achieved.

As described above, according to the second embodiment, in the wiring structure 100, the first sputtering film 14 containing nitrogen is formed on the conductive film 12 by non-reactive sputtering, and the reactivity is formed on the first sputtering film 14. It is manufactured by forming a second sputtering film 15 containing nitrogen by sputtering, and the first sputtering film 14 has a lower nitrogen content than the second sputtering film 15.
Accordingly, the same effects as those of the first embodiment are obtained.

  Further, according to the second embodiment, the wiring structure 100 is manufactured using an apparatus having two or more Al chambers and titanium chambers.

  Therefore, compared with the first embodiment, it is not necessary to perform sputtering in a state where the substrate is shielded by a shutter or a disk for switching between reactive sputtering and non-reactive sputtering, and higher throughput can be realized.

  Next, a third embodiment will be described with reference to FIGS.

  In the third embodiment, the structure in which the third nitrogen-containing film is further formed on the second nitrogen-containing film in the first embodiment is applied to the semiconductor device 200 having a multilayer wiring structure.

  First, the structure of the semiconductor device 200 will be briefly described with reference to FIG.

  As shown in FIG. 8, the semiconductor device 200 includes a lower wiring layer 201, a first wiring layer 203 formed on the lower wiring layer 201, and a second wiring layer 205 formed on the first wiring layer 203. ing.

  More specifically, the lower wiring layer 201 includes a first interlayer insulating film 211, a tungsten wiring 213 formed in a predetermined pattern on the first interlayer insulating film 211, and a tungsten wiring on the first interlayer insulating film 211. A stopper silicon nitride film 215 is formed so as to cover a portion other than the portion where 213 is formed.

  The lower wiring layer 201 further includes a second interlayer insulating film 217 provided on the stopper silicon nitride film 215 and the tungsten wiring 213, and a first tungsten connected to the tungsten wiring 213 through the second interlayer insulating film 217. A plug 219 is provided.

  On the other hand, the first wiring layer 203 is provided on the second interlayer insulating film 217 and on the second interlayer insulating film 217 so as to cover the intermediate wiring layer 221 connected to the first tungsten plug 219 and the intermediate wiring layer 221. A third interlayer insulating film 223 provided on the third interlayer insulating film 223, a fourth interlayer insulating film 225 provided on the third interlayer insulating film 223, and an intermediate wiring through the third interlayer insulating film 223 and the fourth interlayer insulating film 225 A second tungsten plug 227 is connected to the layer 221.

  The second wiring layer 205 is a wiring layer made of aluminum or the like provided on the fourth interlayer insulating film 225.

  Here, the intermediate wiring layer 221 has a structure corresponding to the wiring structure 100 in the first embodiment.

  Specifically, the intermediate wiring layer 221 includes a barrier layer 231 such as Ti, a metal layer 235 such as Al provided on the barrier layer 231, a first nitrogen-containing film 237 provided on the metal layer 235, It has a second nitrogen-containing film 239 provided on the first nitrogen-containing film 237, and further has a third nitrogen-containing film 241 provided on the second nitrogen-containing film 239.

  Further, the first nitrogen-containing film 237 has a lower nitrogen content than the second nitrogen-containing film 239.

  Specifically, for example, the composition of the first nitrogen-containing film 237 is TiNx (x is 0 <x ≦ 0.9), and the composition of the second nitrogen-containing film 239 is TiNx (x is 0.9 <x ≦ 1.1).

  Furthermore, the third nitrogen-containing film 241 has a lower nitrogen content than the second nitrogen-containing film 239.

  Specifically, for example, the composition of the third nitrogen-containing film 241 is TiNx (x is 0.1 <x ≦ 0.2).

  As described above, by forming the third nitrogen-containing film 241 having the lowest nitrogen content in the uppermost layer of the intermediate wiring layer 221, the adhesion between the third interlayer insulating film 223 and the intermediate wiring layer 221 can be further improved. In addition, when the second tungsten plug 227 is formed, the generation of a gap between the third interlayer insulating film 223 and the intermediate wiring layer 221 can be suppressed.

  Next, a method for manufacturing the semiconductor device 200 will be described with reference to FIGS.

  First, as shown in FIG. 10, the lower wiring layer 201 is formed (S31 in FIG. 9).

  Specifically, for example, the tungsten wiring 213 is formed in a predetermined pattern on the first interlayer insulating film 211, and the stopper silicon is formed so as to cover a portion other than the portion where the tungsten wiring 213 is formed on the first interlayer insulating film 211. A nitride film 215 is formed.

  Further, a second interlayer insulating film 217 such as P-SiO is formed on the stopper silicon nitride film 215 and the tungsten wiring 213, and a first tungsten plug 219 is provided so as to penetrate the second interlayer insulating film 217. Connect to wiring 213.

  Next, as shown in FIG. 11, a barrier layer 231 such as Ti or TiN is formed on the lower wiring layer 201, and a metal layer 235 such as Al is formed on the barrier layer 231 by sputtering (S32 in FIG. 9). .

  Next, as shown in FIG. 12, a first nitrogen-containing film 237, a second nitrogen-containing film 239, and a third nitrogen-containing film 241 are formed in this order on the metal layer 235 (S33 in FIG. 9).

  Specifically, first, using the same apparatus as the sputtering apparatus in which the metal layer 235 is formed, a first nitrogen-containing film 237 such as Ti or TiNx is used as a first antireflection film to such an extent that the surface of the metal layer 235 is not nitrided. A film thickness of 1 nm to 5 nm is formed (reactive sputtering under the first condition). The N / Ti ratio at this time is in the range of 0.0 to 0.9.

Next, a second nitrogen-containing film 239 such as TiN is formed to a thickness of 30 nm to 70 nm as a second antireflection film that also serves as an antireflection film for lithography and a stopper for through-hole etching. The film formation conditions at this time are N ₂ = 80 cc, Ar = 28 cc, and the N / Ti ratio is in the range of 0.9 to 1.1 (reactive sputtering under the second condition).

  Next, a third nitrogen-containing film 241 such as TiNx is formed to a thickness of 7 nm to 15 nm as a third antireflection film for ensuring adhesion with the third interlayer insulating film 223.

The film formation condition at this time is a gas flow rate ratio N ₂ : Ar = 2: 7, but the gas flow rate ratio may not be within this range as long as the N / Ti ratio is in the range of 0.1 to 0.2. (Reactive sputtering under the third condition).

As described above, the formation of the nitrogen-containing film is performed by changing the flow rate ratio defined by Ar / N 2 system, N ₂ flow rate = N ₂ flow rate / (Ar flow rate + N ₂ flow rate), with Ti as the target. Change the rules. At this time, when the N ₂ flow rate ratio is too low, the supply law is established, and TiNx (x ≦ 0.9) is formed. Further, the reaction rate is appropriate when the flow rate ratio is appropriate, and TiNx (x is near 1.0) is formed. Note that even when the flow rate ratio is increased from an appropriate flow rate ratio and the flow rate ratio is excessive, TiNx (x is near 1.0) is formed according to the reaction rule, but the reduction in film formation rate due to target surface nitridation becomes obvious. Therefore, it is not preferable.

  Here, when the first nitrogen-containing film 237 is formed, the flow rate ratio of the nitrogen gas to the total flow rate, which is the sum of the flow rate of the inert gas and the nitrogen gas, is the time when the second nitrogen-containing film 239 is formed. The flow rate ratio is lower.

  Further, the flow rate ratio of the nitrogen gas to the total flow rate of the inert gas (Ar here) and the nitrogen gas when forming the third nitrogen-containing film 241 is greater than the flow rate ratio when forming the second nitrogen-containing film 239. Low.

  The above is the method for forming the first nitrogen-containing film 237, the second nitrogen-containing film 239, and the third nitrogen-containing film 241.

  Next, as shown in FIG. 13, dry etching is performed on the barrier layer 231, the metal layer 235, the first nitrogen-containing film 237, the second nitrogen-containing film 239, and the third nitrogen-containing film 241, so that an intermediate portion of a predetermined pattern is obtained. The wiring layer 221 is formed (S34 in FIG. 9).

  Next, as shown in FIG. 13, a third interlayer insulating film 223 of HDP-SiO is formed on the lower wiring layer 201 and the second nitrogen-containing film 239, and further, P− is formed on the third interlayer insulating film 223. A fourth interlayer insulating film 225 such as SiO is formed (S35 in FIG. 9).

  Next, as shown in FIG. 13, through holes 251 (openings) are formed in the third interlayer insulating film 223 and the fourth interlayer insulating film 225 so as to reach the third nitrogen-containing film 241 (S36 in FIG. 9). .

  As described above, the adhesiveness between the third nitrogen-containing film 241 and the third interlayer insulating film 223 is higher than the adhesiveness between the second nitrogen-containing film 239 and the third interlayer insulating film 223, so The peeling of the third interlayer insulating film 223 at the interface between the 3 nitrogen-containing film 241 and the third interlayer insulating film 223 is suppressed.

Next, as shown in FIG. 8, the second tungsten plug 227 is embedded in the through hole 251, and the second wiring layer 205 is provided on the fourth interlayer insulating film 225 to be connected to the second tungsten plug 227 ( S37 in FIG. 9).
The above is the manufacturing method of the semiconductor device 200.

Thus, according to the third embodiment, the intermediate wiring layer 221 of the semiconductor device 200 has the first nitrogen-containing film 237 and the second nitrogen-containing film 239 formed on the metal layer 235 under different sputtering conditions. The first nitrogen-containing film 237 has a lower nitrogen content than the second nitrogen-containing film 239.
Accordingly, the same effects as those of the first embodiment are obtained.

  Further, according to the third embodiment, the intermediate wiring layer 221 further includes the third nitrogen-containing film 241 on the second nitrogen-containing film 239, and the third nitrogen-containing film 241 is the second nitrogen-containing film 239. Less nitrogen content.

  Therefore, even when the intermediate wiring layer 221 is covered with the third interlayer insulating film 223, the occurrence of peeling between the interface of the uppermost layer (the third nitrogen-containing film 241) and the third interlayer insulating film 223 can be suppressed.

  Next, a fourth embodiment will be described with reference to FIGS.

  In the semiconductor device 200a according to the fourth embodiment, in the third embodiment, a lower layer portion 241a and an upper layer portion 241b having different nitrogen contents are provided as the third nitrogen-containing film 241.

  Note that in the fourth embodiment, elements that perform the same functions as in the third embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

  First, the structure of the semiconductor device 200a will be described with reference to FIG.

  The structure of the semiconductor device 200a is the same as that of the semiconductor device 200, except that the third nitrogen-containing film 241 has a two-layer structure in which a lower layer portion 241a and an upper layer portion 241b having different nitrogen contents are provided. Is different.

  Specifically, the upper layer portion 241b has a lower nitrogen content than the lower layer portion 241a.

  For example, the composition of the lower layer portion 241a is TiNx (x is 0.2 <x ≦ 0.5), and the composition of the upper layer portion 241b is TiNx (x is 0.1 <x ≦ 0.2).

  As described above, the third nitrogen-containing film 241 has a two-layer structure in which the lower layer portion 241a and the upper layer portion 241b are provided, so that the N / Ti ratio is the first between the second nitrogen-containing film 239 and the upper layer portion 241b. 2 The lower layer portion 241a (N / T ratio =) between the nitrogen-containing film 239 (N / T ratio = 0.9 to 1.1) and the upper layer portion 241b (N / T ratio = 0.1 to 0.2). 0.2-0.5) is arranged.

  Therefore, not only the peeling between the third nitrogen-containing film 241 and the third interlayer insulating film 223 is suppressed, but also the peeling at the interface between the second nitrogen-containing film 239 and the third nitrogen-containing film 241 is suppressed. it can.

  Next, a method for manufacturing the semiconductor device 200a will be described with reference to FIGS. 9 and 14 to 17.

  First, similarly to the first embodiment, the lower wiring layer 201 is formed, and the barrier layer 231 and the metal layer 235 are formed (S31 and S32 in FIG. 9).

  Next, as shown in FIG. 16, a first nitrogen-containing film 237, a second nitrogen-containing film 239, and a third nitrogen-containing film 241 are formed in this order on the metal layer 235 (S33 in FIG. 9).

  Specifically, first, using the same apparatus as the sputtering apparatus in which the metal layer 235 is formed, a first nitrogen-containing film 237 such as Ti or TiNx is used as a first antireflection film to such an extent that the surface of the metal layer 235 is not nitrided. A film thickness of 1 nm to 5 nm is formed (reactive sputtering under the first condition, S41 in FIG. 15). The N / Ti ratio at this time is in the range of 0.0 to 0.9.

Next, a second nitrogen-containing film 239 such as TiN is formed to a film thickness of 25 nm to 65 nm as a second antireflection film that also serves as an antireflection film for lithography and a stopper for through-hole etching. The film formation conditions at this time are N ₂ = 80 cc, Ar = 28 cc, and the N / Ti ratio is in the range of 0.9 to 1.1 (second condition reactive sputtering, S41 in FIG. 15).

  Next, a lower layer portion 241a such as TiNx is formed to have a film thickness of 5 nm to 10 nm as a third antireflection film for ensuring adhesion with the second nitrogen-containing film 239. At this time, the N / Ti ratio is in the range of 0.2 to 0.5 (S42 in FIG. 15).

Next, an upper layer portion 241b such as TiNx is formed with a film thickness of 5 nm to 10 nm as a third antireflection film for ensuring adhesion with the third interlayer insulating film 223. The film formation condition at this time is a gas flow rate ratio N ₂ : Ar = 2: 7, but the gas flow rate ratio may not be within this range as long as the N / Ti ratio is in the range of 0.1 to 0.2. (Reactive sputtering under the third condition, S43 in FIG. 15).

Thereafter, as in the first embodiment, formation of the intermediate wiring layer 221 by dry etching (S34 in FIG. 9), formation of the third interlayer insulating film 223 and the fourth interlayer insulating film 225 (S35 in FIG. 9), The through hole 251 is formed (S36 in FIG. 9) to form the structure shown in FIG. 17, and finally, the second tungsten plug 227 and the second wiring layer 205 are formed, and the semiconductor device 200a shown in FIG. It is manufactured (S37 in FIG. 9).
The above is the manufacturing method of the semiconductor device 200a.

Thus, according to the fourth embodiment, the intermediate wiring layer 221 of the semiconductor device 200 includes the first nitrogen-containing film 237 and the second nitrogen-containing film 239 formed on the metal layer 235 under different sputtering conditions. The first nitrogen-containing film 237 has a lower nitrogen content than the second nitrogen-containing film 239.
Therefore, the same effects as those of the third embodiment are obtained.

  In addition, according to the fourth embodiment, the intermediate wiring layer 221 has a two-layer structure in which the lower layer portion 241a and the upper layer portion 241b having different nitrogen contents are provided as the third nitrogen-containing film 241. The upper layer portion 241b has a lower nitrogen content than 241a.

  Therefore, not only the peeling between the third nitrogen-containing film 241 and the third interlayer insulating film 223 is suppressed, but also the peeling at the interface between the second nitrogen-containing film 239 and the third nitrogen-containing film 241 is suppressed. it can.

  Next, a fifth embodiment will be described with reference to FIGS. 9 and 18 to 21.

  In the third embodiment, the semiconductor device 200b according to the fifth embodiment includes a lower layer portion 242a, an intermediate portion 242b, and an upper layer portion 242c having different nitrogen contents as the third nitrogen-containing film 241.

  Note that in the fifth embodiment, elements that perform the same functions as in the third embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

  First, the structure of the semiconductor device 200b will be described with reference to FIG.

  The structure of the semiconductor device 200b is the same as the structure of the semiconductor device 200. However, the third nitrogen-containing film 241 has a three-layer structure in which a lower layer portion 242a, an intermediate portion 242b, and an upper layer portion 242c having different nitrogen contents are provided. Only the difference is.

  Specifically, the intermediate portion 242b has a lower nitrogen content than the lower layer portion 242a, and the upper layer portion 242c has a lower nitrogen content than the intermediate portion 242b.

  For example, the composition of the lower layer portion 241a is TiNx (x is 0.5 <x ≦ 0.9), the composition of the intermediate portion 242b is TiNx (x is 0.2 <x ≦ 0.5), and the composition of the upper layer portion 241b is TiNx (x is 0.1 <x ≦ 0.2).

  As described above, the third nitrogen-containing film 241 has a three-layer structure in which the lower layer part 242a, the intermediate part 242b, and the upper layer part 242c are provided (that is, the second nitrogen-containing film 239 and the third nitrogen film 239 in the fourth embodiment). By making the lower layer portion 241a for preventing the peeling of the nitrogen-containing film 241 into two layers in which the N / Ti ratio is further finely changed, the second nitrogen-containing film 239 and the third nitrogen-containing film 241 It is possible to further improve the adhesion at the interface and suppress peeling.

  Next, a method for manufacturing the semiconductor device 200b will be described with reference to FIG. 9 and FIGS.

  First, similarly to the first embodiment, the lower wiring layer 201 is formed, and the barrier layer 231 and the metal layer 235 are formed (S31 and S32 in FIG. 9).

  Next, as shown in FIG. 20, a first nitrogen-containing film 237, a second nitrogen-containing film 239, and a third nitrogen-containing film 241 are formed in this order on the metal layer 235 (S33 in FIG. 9).

  Specifically, first, using the same apparatus as the sputtering apparatus in which the metal layer 235 is formed, a first nitrogen-containing film 237 such as Ti or TiNx is used as a first antireflection film to such an extent that the surface of the metal layer 235 is not nitrided. A film thickness of 1 nm to 5 nm is formed (reactive sputtering under the first condition, S51 in FIG. 19). The N / Ti ratio at this time is in the range of 0.0 to 0.9.

Next, a second nitrogen-containing film 239 such as TiN is formed to a film thickness of 25 nm to 65 nm as a second antireflection film that also serves as an antireflection film for lithography and a stopper for through-hole etching. The film formation conditions at this time are N ₂ = 80 cc, Ar = 28 cc, and the N / Ti ratio is in the range of 0.9 to 1.1 (second condition reactive sputtering, S51 in FIG. 19).

  Next, a lower layer portion 242a such as TiNx is formed to have a film thickness of 5 nm to 10 nm as a third antireflection film for ensuring adhesion with the second nitrogen-containing film 239. At this time, the N / Ti ratio is in the range of 0.5 to 0.9 (S52 in FIG. 15).

  Next, an intermediate portion 242b such as TiNx is formed with a film thickness of 5 nm to 10 nm as a fourth antireflection film for ensuring adhesion with the third interlayer insulating film 223. At this time, the N / Ti ratio is in the range of 0.2 to 0.5 (S53 in FIG. 15).

Next, an upper layer portion 242c such as TiNx is formed to have a film thickness of 5 nm to 10 nm as a fifth antireflection film for ensuring adhesion with the third interlayer insulating film 223. The film formation condition at this time is a gas flow rate ratio N ₂ : Ar = 2: 7, but the gas flow rate ratio may not be within this range as long as the N / Ti ratio is in the range of 0.1 to 0.2. (Reactive sputtering under the third condition, S54 in FIG. 15).

Thereafter, as in the first embodiment, formation of the intermediate wiring layer 221 by dry etching (S34 in FIG. 9), formation of the third interlayer insulating film 223 and the fourth interlayer insulating film 225 (S35 in FIG. 9), The through hole 251 is formed (S36 in FIG. 9) to form the structure shown in FIG. 21, and finally the second tungsten plug 227 and the second wiring layer 205 are formed, thereby manufacturing the semiconductor device 200b (see FIG. S37 in FIG. 9).
The above is the manufacturing method of the semiconductor device 200b.

Thus, according to the fifth embodiment, the intermediate wiring layer 221 of the semiconductor device 200b has the first nitrogen-containing film 237 and the second nitrogen-containing film 239 formed on the metal layer 235 under different sputtering conditions. The first nitrogen-containing film 237 has a lower nitrogen content than the second nitrogen-containing film 239.
Therefore, the same effects as those of the third embodiment are obtained.

  Further, according to the fifth embodiment, the intermediate wiring layer 221 has a three-layer structure in which the lower nitrogen portion 242a, the intermediate portion 242b, and the upper layer portion 242c having different nitrogen contents are provided as the third nitrogen-containing film 241. The intermediate portion 242b has a lower nitrogen content than the lower layer portion 242a, and the upper layer portion 242c has a lower nitrogen content than the intermediate portion 242b.

  Therefore, not only the peeling between the third nitrogen-containing film 241 and the third interlayer insulating film 223 is suppressed, but also the peeling at the interface between the second nitrogen-containing film 239 and the third nitrogen-containing film 241 is further suppressed. be able to.

  Hereinafter, based on an Example, this invention is demonstrated concretely.

  The wiring structure 100 shown in FIG. 1 was manufactured by the procedure shown in FIG. 3, and the specific resistance of the wiring was evaluated. The specific procedure is as follows.

Example 1
First, the substrate 10 is placed in the chamber, and the first titanium nitride is applied to the semiconductor substrate (substrate 10) at a nitrogen flow rate ratio (N ₂ flow rate / (Ar flow rate + N ₂ flow rate)) such that the deposition rate is 1000 A / min. The film 11 was formed by reactive sputtering, and then an AlCu film was formed as the conductive film 12 by sputtering. The first sputtering film 14 was formed by non-reactive sputtering at a nitrogen flow rate ratio of 30% so that the deposition rate was 3000 A / min without exposure to the atmosphere. The film thickness was 5 to 8 nm, and the film was formed to such an extent that the in-plane uniformity of the substrate can be secured satisfactorily.

  Next, the nitrogen flow rate ratio is increased so that the reactive flow rate can be 50 to 80%, the substrate stage is covered with a shutter or a disk, the substrate 10 is shielded, and sputtering is performed to sufficiently nitride the titanium target. did.

After that, the second sputtering film 15 was formed by reactive sputtering on the first sputtering film 14 so as to have a nitrogen flow rate ratio of 70% so that the deposition rate was 1000 A / min. .
The wiring structure 100 was manufactured by the above procedure.

(Comparative example)
A wiring structure was manufactured in the same manner as in Example except that the first sputtering film 14 was not formed.

<Comparison of specific resistance>
When the specific resistances of the conductive film of the example and the conductive film of the comparative example were compared, the specific resistance of the example was 100 μΩcm, whereas the specific resistance of the comparative example was 300 μΩcm.

  From this result, it was found that the example can suppress an increase in the layer resistance.

  Moreover, from this result, it was found that the conductive film of the example had one third of the amount of nitrogen that affects the electrical resistance as compared with the conductive film of the comparative example.

(Example 2)
In order to confirm the relationship between the layer resistance of the AlTi alloy and the conductive layer, Ti having various thicknesses was formed on the Al film, and the change in the layer resistance was measured. The results are shown in FIG.

  As shown in FIG. 7, the layer resistance when the Ti film thickness on the Al film is 20 nm is increased by 45% compared to the case where the Ti film thickness is 0 nm (only for the Al film), whereas the Ti film thickness is increased. In the case of 5 nm, the increase was only 6.5% compared to the case of 0 nm.

  This result suggests that the layer resistance decreases when the amount of the AlTi alloy is lowered, and the formation of the AlTi alloy in the Al film due to the small amount of N atoms mixed in the conductive layer as in Example 1. It has been found that the increase in the layer resistance of the Al wiring can be avoided if this is hindered.

(Appendix)
The present invention is also described as in the following supplementary notes, but is not limited to the following.

(Appendix 1)
A wiring structure in which a first sputtering film containing nitrogen is formed on a conductive film by non-reactive sputtering, and a second sputtering film containing nitrogen is formed on the first sputtering film by reactive sputtering. Manufacturing method.

(Appendix 2)
The wiring structure manufacturing method according to appendix 1, wherein the first sputtering film has a lower nitrogen content than the second sputtering film.

(Appendix 3)
(A) forming a first titanium nitride film on the substrate;
(B) forming a conductive film on the first titanium nitride film;
(C) forming a second titanium nitride film on the conductive film;
(C) forming the first sputtering film on the conductive film by non-reactive sputtering, and forming the second sputtering film on the first sputtering film by reactive sputtering; Or the manufacturing method of the wiring structure as described in any one of 2.

(Appendix 4)
The method for manufacturing a wiring structure according to any one of appendices 1 to 3, wherein a film containing Al is formed as the conductive film.

(Appendix 5)
The method for manufacturing a wiring structure according to appendix 4, wherein a film containing AlCu is formed as the conductive film.

(Appendix 6)
The manufacturing method of the wiring structure as described in any one of appendix 1-5 which performs reactive sputtering continuously from non-reactive sputtering.

(Appendix 7)
Forming the first sputtering film by non-reactive sputtering using a titanium target in an inert gas and nitrogen gas atmosphere;
The method for manufacturing a wiring structure according to any one of appendices 1 to 6, wherein the second sputtering film is formed by reactive sputtering after nitriding the titanium target.

(Appendix 8)
Forming the first sputtering film by non-reactive sputtering using a titanium target in an inert gas and nitrogen gas atmosphere;
The wiring structure according to appendix 7, wherein after the titanium target is nitrided with the substrate shielded by a shutter or a disk, the shutter or disk is unshielded and the second sputtering film is formed by reactive sputtering. Manufacturing method.

(Appendix 9)
Forming the first sputtering film by non-reactive sputtering using a titanium target in an inert gas and nitrogen gas atmosphere;
9. The appendix 7 or 8, wherein the second sputtering film is formed by reactive sputtering after nitriding the titanium target by increasing the nitrogen gas flow rate ratio compared to the non-reactive sputtering. Method of manufacturing the wiring structure.

(Appendix 10)
Forming the first sputtering film by non-reactive sputtering in a non-reactive sputtering chamber;
The method for manufacturing a wiring structure according to appendix 7, wherein the second sputtering film is formed by reactive sputtering in a chamber for reactive sputtering.

(Appendix 11)
The method for manufacturing a wiring structure according to any one of appendices 7 to 10, wherein the inert gas includes Ar.

(Appendix 12)
A conductive film;
A first sputtering film provided on the conductive film and containing nitrogen;
A second sputtering film provided on the first sputtering film and containing nitrogen;
Have
The wiring structure in which the first sputtering film has a lower nitrogen content than the second sputtering film.

(Appendix 13)
The first sputtering film is formed by non-reactive sputtering,
The wiring structure according to appendix 12, wherein the second sputtering film is formed by reactive sputtering.

(Appendix 14)
A substrate,
A first titanium nitride film containing nitrogen and provided on the substrate;
A conductive film provided on the first titanium nitride film;
A second titanium nitride film provided on the conductive film;
Have
The second titanium nitride film is
The first sputtering film provided on the conductive film;
14. The wiring structure according to appendix 13, comprising the second sputtering film provided on the first sputtering film.

(Appendix 15)
The wiring structure according to any one of appendix 13 or 14, wherein the conductive film is a film containing Al.

(Appendix 16)
The wiring structure according to appendix 15, wherein the conductive film is a film containing AlCu.

(Appendix 17)
The first sputtering film is formed by non-reactive sputtering using a titanium target in an inert gas and nitrogen gas atmosphere,
The wiring structure according to any one of appendices 13 to 16, wherein the second sputtering film is formed by reactive sputtering after nitriding the titanium target.

(Appendix 18)
The second titanium nitride film is formed by non-reactive sputtering using a titanium target in an inert gas and nitrogen gas atmosphere,
The wiring structure according to appendix 17, wherein the second sputtering film is formed by reactive sputtering after nitriding the titanium target by increasing the nitrogen gas flow rate compared to the non-reactive sputtering.

(Appendix 19)
The wiring structure according to any one of appendix 17 or 18, wherein the inert gas includes Ar.

(Appendix 20)
A semiconductor device having the wiring structure according to any one of appendices 12 to 19.

  As mentioned above, although the invention made | formed by this inventor was demonstrated based on embodiment and an Example, it cannot be overemphasized that this invention is not limited to the said Example, and can be variously changed in the range which does not deviate from the summary. Yes.

DESCRIPTION OF SYMBOLS 10 ......... Substrate 11 ......... First titanium nitride film 12 ......... conductive film 13 ......... second titanium nitride film 14 ...... first sputtering film 15 ......... second sputtering film 100 ... wiring structure (Semiconductor device)
DESCRIPTION OF SYMBOLS 200 ... Semiconductor device 200a ... Semiconductor device 200b ... Semiconductor device 201 ... Lower wiring layer 203 ... First wiring layer 205 ... Second wiring layer 211 ... First interlayer insulating film 213 ... Tungsten wiring 215 ... Stopper Silicon nitride film 217 ... second interlayer insulating film 219 ... first tungsten plug 221 ... intermediate wiring layer 223 ... third interlayer insulating film 225 ... fourth interlayer insulating film 227 ... second tungsten plug 231 ... Barrier layer 235 ... Metal layer 237 ... First nitrogen-containing film 239 ... Second nitrogen-containing film 241 ... Third nitrogen-containing film 241a ... Lower layer part 241b ... Upper layer part 242a ... Lower layer part 242b ... Intermediate part 242c ... Part 251 ... Through hole

Claims (15)

(A) forming a first nitrogen-containing film on the metal layer by first reactive sputtering;
(B) forming a second nitrogen-containing film on the first nitrogen-containing film by reactive sputtering under a second condition;
Have
The method of manufacturing a semiconductor device, wherein the first nitrogen-containing film has a lower nitrogen content than the second nitrogen-containing film.   The composition of the first nitrogen-containing film is TiNx (x is 0 <x ≦ 0.9), and the composition of the second nitrogen-containing film is TiNx (x is 0.9 <x ≦ 1.1). A method for manufacturing a semiconductor device. (C) forming a third nitrogen-containing film on the second nitrogen-containing film by reactive sputtering under a third condition;
Have
2. The method of manufacturing a semiconductor device according to claim 1, wherein the third nitrogen-containing film has a nitrogen content lower than that of the second nitrogen-containing film.   The method of manufacturing a semiconductor device according to claim 3, wherein the composition of the third nitrogen-containing film is TiNx (x is 0.1 <x ≦ 0.2). (C) forms, as the third nitrogen-containing film, a lower layer portion having a composition of TiNx (x is 0.2 <x ≦ 0.5) and an upper layer portion having a composition of TiNx (x is 0.1 <x ≦ 0.2). To
The manufacturing method of the semiconductor device of Claim 3 which has these. The (c) is the third nitrogen-containing film,
A lower layer portion having a composition of TiNx (x is 0.5 <x ≦ 0.9) is formed, and an intermediate layer portion having a composition of TiNx (x is 0.2 <x ≦ 0.5) is formed on the lower layer portion, and the composition is TiNx (x is 0.1). <X ≦ 0.2) forming the upper layer part,
The manufacturing method of the semiconductor device of Claim 3 which has these. (D) A first nitrogen-containing film and a second nitrogen-containing film are sequentially formed on the metal layer using a titanium target in an atmosphere containing an inert gas and a nitrogen gas.
Have
(D) indicates that the flow rate ratio of the nitrogen gas to the total flow rate, which is the sum of the flow rate of the inert gas and the flow rate of the nitrogen gas when forming the first nitrogen-containing film, is the second nitrogen. The manufacturing method of a semiconductor device lower than the flow rate ratio at the time of forming a containing film. (E) forming a third nitrogen-containing film on the second nitrogen-containing film using the titanium target in an atmosphere containing the inert gas and the nitrogen gas;
Have
(E) is a flow rate of the nitrogen gas with respect to a total flow rate of the inert gas and the nitrogen gas when forming the third nitrogen-containing film, and a flow rate when forming the second nitrogen-containing film. The method for manufacturing a semiconductor device according to claim 7, wherein the method is lower than the ratio.   The method for manufacturing a semiconductor device according to claim 8, wherein the inert gas is Ar. (F) forming a barrier film on the substrate;
(G) forming a metal layer on the barrier film;
(H) forming a first nitrogen-containing film on the metal layer;
(I) forming a second nitrogen-containing film having a nitrogen content higher than that of the first nitrogen-containing film on the first nitrogen-containing film;
(J) forming a third nitrogen-containing film having a nitrogen content lower than that of the second nitrogen-containing film on the second nitrogen-containing film;
(K) patterning the third, second and first nitrogen-containing films, the metal layer and the barrier film into a wiring having a desired shape;
(L) forming an interlayer insulating film covering the wiring;
(M) providing an opening in the interlayer insulating film so that a part of the third nitrogen-containing film is exposed;
A method for manufacturing a semiconductor device, comprising:   The method of manufacturing a semiconductor device according to claim 10, wherein the first, second, and third nitrogen-containing films are formed using a titanium target in an atmosphere containing an inert gas and a nitrogen gas.   The method for manufacturing a semiconductor device according to claim 11, wherein the inert gas is Ar.   The method of manufacturing a semiconductor device according to claim 10, wherein the composition of the third nitrogen-containing film is TiNx (x is 0.1 <x ≦ 0.2).   (J) forms, as the third nitrogen-containing film, a lower layer portion having a composition of TiNx (x is 0.2 <x ≦ 0.5), and the composition is TiNx (x is 0.1 <x ≦ 0.2) on the lower layer portion. The method for manufacturing a semiconductor device according to claim 10, wherein an upper layer portion of the semiconductor device is formed.   (J) forms a lower layer portion having a composition of TiNx (x is 0.5 <x ≦ 0.9) as the third nitrogen-containing film, and the composition is TiNx (x is 0.2 <x ≦ 0.5) on the lower layer portion. 11. The method of manufacturing a semiconductor device according to claim 10, wherein an intermediate portion of the first layer is formed, and an upper layer portion having a composition of TiNx (x is 0.1 <x ≦ 0.2) is formed on the intermediate portion.

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