JP2006249580A - Thin film laminate structure, method for formation thereof, film formation apparatus, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for thin film laminate structure formation that has high adhesion to a substrate and thus can suppress film separation, can satisfactorily enhance a step coverage even in the case of enhanced fineness, and can achieve satisfactory diffusion of alloying species elements. <P>SOLUTION: In this method, a plurality of thin films are deposited on a surface of an object within an evacuatable treatment vessel 4 to form a thin film laminate structure. In this case, an alloying species film formation step of forming a first metal alloy species film 104 using a starting material gas containing a first metal as an alloying species and a reducing gas and a base material film formation step of forming a second metal base material film 106, in a large thickness than the thickness of the alloying species film, using a starting material gas containing a second metal as a base material different from the first metal, and a reducing gas, are alternately carried out once or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminated structure of thin films formed on the surface of an object to be processed such as a semiconductor wafer, a method for forming the same, a film forming apparatus for executing the method, and a storage medium for storing a program for controlling the film forming apparatus.

In general, in order to manufacture a semiconductor integrated circuit such as an IC or LSI, a film forming process, an etching process, an oxidation diffusion process, an annealing process, a modification process, and the like are repeatedly performed on an object to be processed such as a semiconductor wafer. ing. Recently, there has been a demand for higher integration, higher miniaturization, and higher speed of operation, and therefore, with regard to wiring layers, etc., further thinning and line width miniaturization have been promoted. Yes. Under such circumstances, instead of the conventional aluminum wiring, a copper wiring with lower electrical resistance has been proposed (for example, Patent Document 1). In order to form a wiring or the like with this copper film, generally a desired wiring pattern is formed by forming a copper film on the wafer surface or the like using a sputtering apparatus and scraping off an unnecessary portion of the copper film. Is supposed to form.
By the way, unlike conventional aluminum wiring, copper wiring is very susceptible to electromigration and stress migration at the boundary with other materials, such as silicon. Peeling easily occurs. In particular, as the miniaturization progresses, this decrease in adhesion cannot be ignored.

  Therefore, in order to reduce the migration, it is also possible to make a wiring pattern with a copper alloy formed by adding, for example, about 1% of another metal, for example, Ti or Al, as an alloy species in the copper film. Proposed. In this case, a target made of a copper alloy in which an alloy species such as Ti is added at a desired concentration, for example, about several percent, is prepared, and a thin film made of a copper alloy is formed on the wafer by plasma sputtering using the target. It is designed to form on the surface.

JP 2000-77365 A

By the way, as described above, the copper alloy film is formed by the sputtering process. However, in the film formation by the sputtering process, the step coverage satisfies the requirements especially for today's design rules in which the line width and the like are further refined. This makes it difficult to fill the recesses on the wafer surface sufficiently.
Also, in the deposited copper alloy film, even if there is a case where it is desired to form the film in a state where the concentration of the alloy species is higher than the other part at the boundary part with the desired part, for example, the base layer, the copper alloy film The concentration of the alloy species in the copper alloy film is defined by the concentration of the alloy species in the metal target manufactured in advance, and the alloy species concentration cannot be changed during sputter deposition. It was not possible to perform concentration control such that, for example, the concentration of the liquid was increased only at a specific site. For this reason, since migration cannot be sufficiently suppressed, sufficient adhesion cannot be obtained, and in some cases, the occurrence of film peeling cannot be prevented.

Therefore, it is conceivable to form the copper alloy film by CVD (Chemical Vapor Deposition) instead of sputtering, but in this case, only one kind of metal film can be formed at a time, and the CVD method is simply used. However, there is a problem that the metal atoms of the alloy type cannot be uniformly mixed or dispersed throughout the film only by adopting.
The present invention has been devised to pay attention to the above problems and to effectively solve them. The object of the present invention is to have high adhesion to the substrate and suppress the occurrence of film peeling, and even if the miniaturization progresses, the step coverage can be made sufficiently high, and further the elements of the alloy species can be sufficiently diffused. An object of the present invention is to provide a laminated structure of thin films, a method for forming the same, a film forming apparatus, and a storage medium.

  According to a first aspect of the present invention, there is provided a method of depositing a plurality of thin films on a surface of an object to be processed in a processing vessel that can be evacuated to form a laminated structure of thin films. An alloy seed film forming step of forming an alloy seed film made of a first metal using a source gas containing and a reducing gas; and a source gas containing a second metal as a base material different from the first metal; A base material film forming step of forming a base material film made of a second metal thicker than the alloy seed film using a reducing gas is alternately performed at least once each. This is a method of forming a laminated structure.

  As described above, the alloy seed film forming step for forming the alloy seed film made of the first metal that is the alloy seed and the base material film forming step for forming the base material film made of the second metal are each performed once or more. Since the alloy layers are formed alternately, it is possible to suppress the occurrence of film peeling with high adhesion to the base, and to sufficiently increase the step coverage even if miniaturization progresses. Furthermore, it is possible to sufficiently diffuse the alloy species.

In this case, for example, as defined in claim 2, in the alloy seed film forming step, the source gas containing the first metal and the reducing gas are intermittently supplied into the processing vessel at different timings. One of an intermittent film formation method in which film formation is performed and a continuous film formation method in which a source gas containing a first metal and a reducing gas are simultaneously supplied into the processing container to form a film continuously. One film forming method is performed.
Further, for example, as defined in claim 3, in the base material film forming step, the source gas containing the second metal and the reducing gas are alternately supplied into the processing vessel at different timings. One of an intermittent film forming method for forming a film and a continuous film forming method for continuously forming a film by supplying a source gas containing a second metal and a reducing gas into the processing vessel at the same time. A film forming method is performed.
Further, for example, as defined in claim 4, an annealing step of heating the workpiece to a predetermined temperature after alternately performing the alloy seed film forming step and the base material film forming step one or more times respectively. Do.

For example, as defined in claim 5, the alloy seed film forming step and the base material film forming step are performed in the same processing vessel.
Further, for example, as defined in claim 6, the alloy seed film forming step and the base material film forming step are performed alternately in different processing vessels.
Further, for example, as defined in claim 7, the thickness of one layer of the alloy seed film is in the range of 1 to 200 mm, and the thickness of one layer of the base material film is in the range of 5 to 500 mm. is there.
For example, as defined in claim 8, the first metal is selected from the group consisting of Ti, Sn, W, Ta, Mg, In, Al, Ag, Co, Nb, B, V, and Mn. One metal.

For example, as defined in claim 9, the second metal is one metal selected from the group consisting of Cu, Ag, Au, and W.
Further, for example, as defined in claim 10, the reducing gas is H ₂ , NH ₃ , N ₂ , N ₂ H ₄ [hydrazine], NH (CH ₃ ) ₂ [ethylamine], N ₂ H ₃ CH [methyldiazene. ], One or more gases selected from the group consisting of N ₂ H ₃ CH ₃ [methylhydrazine].

According to an eleventh aspect of the present invention, in the laminated structure of the thin film formed on the surface of the object to be processed, the first metal formed using the source gas containing the first metal as the alloy species and the reducing gas. And a base material made of a second metal thicker than the alloy seed film using a source gas containing a second metal as a base material different from the first metal and a reducing gas. It is a thin film laminated structure characterized in that one or more material films are alternately laminated.
In this case, for example, as defined in claim 12, the thickness of one layer of the alloy seed film is in the range of 1 to 200 mm, and the thickness of one layer of the base material film is in the range of 5 to 500 mm. Is within.

According to a thirteenth aspect of the present invention, there is provided a film forming apparatus for depositing a thin film on a surface of an object to be processed, a processing container that can be evacuated, a mounting table for mounting the object to be processed, Heating means for heating; gas introducing means for introducing gas into the processing vessel; first raw material gas supplying means for supplying a raw material gas containing a first metal as an alloy species to the gas introducing means; A second raw material gas supply means for supplying a raw material gas containing a second metal as a base material to the gas introduction means; a reducing gas supply means for supplying a reducing gas to the gas introduction means; And control means for controlling the alloy seed film made of the first metal and the base material film made of the second metal to alternately form one or more layers. Device.
In this case, for example, as defined in claim 14, a plasma forming means is provided for generating plasma in the processing container.

  The invention according to claim 15 includes a first metal as an alloy seed when a plurality of thin films are deposited on the surface of an object to be processed in a processing vessel that can be evacuated to form a laminated structure of the thin films. An alloy seed film forming step of forming an alloy seed film made of a first metal using a source gas and a reducing gas, and a source gas containing a second metal as a base material different from the first metal and a reduction A program for controlling a film forming apparatus is stored so that a base material film forming step of forming a base material film made of a second metal thicker than the alloy seed film using gas is alternately performed at least once. Storage medium.

According to the laminated structure of the thin film, the method for forming the thin film, the film forming apparatus, and the storage medium according to the present invention, the following excellent operational effects can be exhibited.
An alloy seed film forming step for forming an alloy seed film made of a first metal that is an alloy seed and a base material film forming step for forming a base material film made of a second metal are alternately performed at least once. Since the alloy layer is formed, the adhesion to the base is high and the occurrence of film peeling can be suppressed, and the step coverage can be sufficiently increased even if miniaturization progresses. This element can be sufficiently diffused.

Hereinafter, an embodiment of a thin film laminated structure, a method for forming the same, a film forming apparatus, and a storage medium according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram showing an example of a film forming apparatus according to the present invention.
First, the film forming apparatus of the present invention will be described. The film forming apparatus 2 includes a processing container 4 formed into a cylindrical shape with, for example, aluminum. The processing container 4 is grounded, and an exhaust port 6 is formed at the bottom thereof. A vacuum exhaust system 12 having a pressure control valve 8 and a vacuum pump 10 interposed in the middle is connected to the exhaust port 6 so that the inside of the processing vessel 4 can be evacuated and set to an arbitrary pressure. It has become.

  A gate valve 16 is provided on the side wall of the processing container 4 to be opened and closed when the semiconductor wafer 14 that is the object to be processed is carried into and out of the processing container 4. In addition, in the processing container 4, a mounting table 18 is provided which is erected from the bottom thereof and also serves as a lower electrode. A thin electrostatic chuck 20 is provided on the upper surface of the mounting table 18, for example. The wafer 14 is attracted and held on the electrostatic chuck 20 by an electrostatic force, and the electrostatic chuck 20 is made conductive with respect to a high frequency to serve as a lower electrode. Further, inside the mounting table 18 is provided a heating means 22 composed of, for example, a heater for heating the wafer W to a predetermined temperature. A heating lamp may be used as the heating means 22 instead of the heater.

  In addition, for example, a shower head 24 is provided on the ceiling portion of the processing container 4 via an insulating member 26 as gas introducing means for introducing a predetermined necessary gas into the container. A number of gas injection ports 24A are provided on the lower surface of the shower head 24, and a gas introduction port 24B is provided on the upper portion, so that necessary gas can be injected into the container from the gas injection ports 24A. It is like that. For convenience, only one gas inlet 24B is shown as a representative, but actually, a plurality of gas inlets 24B are separately provided corresponding to the type of gas to be supplied, and various types of supplied gas are supplied to the shower head 24. In the shower head 24, and in the case where it should not be mixed, the shower head 24 flows in a separated state and is injected from the gas injection 24 </ b> A. Will be mixed.

  The shower head 24 is connected with a plasma forming means 30, and is also used as an upper electrode for the lower electrode of the mounting table 18 disposed to face the shower head 24. Specifically, the plasma forming means 30 is configured such that a matching circuit 32 and a high frequency power supply 34 are sequentially provided on a power supply line 36, and the power supply line 36 is connected to the shower head 24, so Plasma can be built inside. Here, as the high frequency power supply 34, for example, a high frequency of 13.56 MHz can be used, but this frequency is not particularly limited.

  The shower head 24 is supplied with a first source gas supply means 40 for supplying a source gas containing a first metal as an alloy species, and a first source gas containing a second metal as a base material. Two source gas supply means 42 and a reducing gas supply means 44 for supplying a reducing gas are connected to each other. Here, the raw material gases are formed by vaporizing raw materials that are liquid or solid at normal temperature and pressure, but the generation method of the raw material gas is not particularly limited, and the raw material gas is directly supplied from the gas cylinder. Gas may be allowed to flow.

First, the first raw material gas supply means 40 has a raw material tank 48 for storing a liquid raw material 46 containing a first metal that is an alloy type. Here, Ti (titanium) is used as the first metal, and TiCl ₄ (titanium tetrachloride) is used as the liquid raw material 46. A raw material channel 49 is provided between the raw material tank 48 and the gas inlet 24B of the shower head 24, and the liquid flow rate controller 50 and the vaporizer 52 are provided in the raw material channel 49 from the upstream side to the downstream side. The liquid raw material 46 is supplied while controlling the flow rate. In this case, the raw material tank 48 is connected to a pressurized gas passage 56 for supplying an inert gas pressurized as necessary, for example, Ar gas. The liquid raw material 46 is pumped. A plurality of on-off valves 54 are provided in the middle of the raw material flow path 49 to stop the flow of the raw material as necessary.

  The vaporizer 52 is connected to a carrier gas passage 62 having a flow controller 58 such as a mass flow controller and an on-off valve 60 in the middle, and vaporizes an inert gas such as Ar gas as the carrier gas. It supplies to the container 52 as needed. Therefore, the source gas vaporized by the vaporizer 52 flows through the source channel 49 together with the carrier gas and is supplied to the shower head 24. Note that a tape heater for preventing re-liquefaction of the raw material gas is preferably wound around the raw material channel 49 downstream of the vaporizer 52.

The second source gas supply means 42 has a source tank 66 for storing a solid source 64 containing a second metal as a base material. Here, Cu (copper) is used as the second metal, and Cu (hfac) ₂ is used as the solid raw material 64. The raw material tank 66 is heated by a heater or the like in order to sublimate the solid raw material 64. A raw material flow path 68 is provided between the raw material tank 66 and the gas inlet port 24B of the shower head 24, and a flow rate controller 70 is provided in the raw material flow path 68. The raw material 64 is supplied. In this case, a gas path 74 for supplying an inert gas, for example, Ar gas, as a carrier gas is connected to the raw material flow path 68, and the solid raw material 64 in the raw material tank 66 is sublimated by this Ar gas while showering. The head 24 is supplied. In the middle of the raw material flow path 68, a plurality of on-off valves 76 are provided for stopping the flow of the raw material as necessary. Note that a tape heater for preventing the liquefaction of the raw material gas is preferably wound around the raw material channel 68 on the downstream side of the raw material tank 66.

The reducing gas supply means 44 has a reducing gas path 84 connected to the gas inlet 24B of the shower head 24, and a flow rate controller 86 such as a mass flow controller and an on-off valve are connected to the reducing gas path 84. 88, for example, H ₂ gas can be supplied as the reducing gas while controlling the flow rate. The reducing gas passage 84 is branched in the middle, and an inert gas, for example, Ar gas can be supplied to the branch passage through a flow controller 90 and an on-off valve 92 as necessary. Yes. If necessary, other means for supplying an inert gas such as N ₂ gas may be provided, but the description thereof is omitted here.

  In order to control the operation of the entire film forming apparatus, that is, pressure control in the processing container 4, temperature control, flow rates of various gases, supply / supply stop control, and the like, a control means 94 such as a computer is provided. The control means 94 has a storage medium 96 such as a floppy disk or a flash memory for storing a program for performing the control.

Next, a film forming method performed using the film forming apparatus 2 configured as described above will be described with reference to FIGS.
FIG. 2 is a process diagram showing the flow of the method of the present invention, FIG. 3 is a sectional view showing an example of a laminated structure of thin films, FIG. 4 is a timing chart showing the timing of supplying each gas, and FIG. It is a figure which shows the density | concentration profile of Cu and Cu.
First, in the method of the present invention, an alloy seed film forming step of forming an alloy seed film made of a first metal using a source gas containing a first metal as an alloy seed and a reducing gas, and the first metal A base material film forming step for forming a base material film made of the second metal thicker than the alloy seed film using a source gas containing a second metal as a base material different from the above and a reducing gas, respectively, In this order, it is alternately performed once or more.

  Specifically, as shown in FIG. 2, the alloy seed film forming step is performed to form a first metal, here an alloy seed film made of Ti (S1), and then the base material film forming step. By performing this, a base material film is formed on the alloy seed film (S2). Then, the above steps are repeated in the above-described order for a necessary number of times, for example, n times (where n is an arbitrary positive number of 1 or more) (S3). Here, the above two steps are performed in the same processing container (film forming apparatus) 4.

  As a result, as shown in FIG. 3, thin films having a laminated structure, that is, alloy layers 100 and 102 are formed on the semiconductor wafer 14, respectively. That is, in FIG. 3, the alloy seed film 104 made of Ti film and the base material film 106 made of Cu film are repeatedly formed on the wafer 14 once or more times in this order. In the case of FIG. 3A, “n = 1”, and each of the films 104 and 106 is formed by one layer. In the case of FIG. 3B, “n = 3”, and each of the films 104 and 106 is alternately formed in three layers. The thickness t2 of the base material film 106 is set to be thicker than the thickness t1 of the alloy seed film, so that the Cu film becomes an alloy base material. Here, the surface (underlying) of the semiconductor wafer 14 before the above films are deposited may be in various states, which may be silicon or some barrier layer or the like. However, the state of the base is not questioned.

  Here, each of the films 104 and 106 has a laminated structure. At the time of actual film formation, the wafer 14 is heated to a certain temperature, for example, about 100 to 400 ° C. Under such a temperature, The atoms of the respective metals forming the alloy seed film 104 and the base material film 106 are thermally diffused to each other. Therefore, the laminated structure of these two kinds of metal films moves and fuses between the films by thermal diffusion of atoms of each metal as described above, and as described above, the alloy having Cu as a whole as a whole. Layers 100 and 102 are formed. As a result, as a matter of course, the Ti concentration in the alloy containing Cu as a base material is the profile (in which the portion of the alloy seed film 104 is the highest and gradually decreases toward the center of the thickness of the base material film 106). Distribution).

  Such a Ti concentration distribution greatly depends on the thicknesses t1 and t2 of the alloy seed film 104 and the base material film 106, although it depends on the temperature at the time of film formation. Then, each film of the alloy seed film 104 and the base material film 106 is sufficiently thermally diffused to an alloy seed concentration (Ti concentration) that can sufficiently enhance the adhesion of the alloy layers 100 and 102 to the base. The thicknesses t1 and t2 are preferably as thin as possible. For example, the thickness of the alloy seed film 104 is in the range of 1 to 200 mm, more preferably in the range of 5 to 50 mm, and the thickness t2 of the base material film 106 is 5 to 500 mm. Each is preferably set within the range. Thus, when the alloy seed film 104 and the base material film 106 are thin, unlike the case shown in FIG. 2, the base material film 106 is first formed, and then the alloy seed film 104 is formed on the base material film 106. You may make it reverse the order of lamination | stacking so that it may form.

Here, a method of forming each of the above films will be described.
In FIG. 1, when supplying Ti source gas which is the first metal, TiCl ₄ which is the liquid source is pumped from the source tank 48 of the first source gas supply means 40 while controlling the flow rate. The raw material gas of TiCl ₄ is formed by vaporizing in the vaporizer 52, this raw material gas is supplied together with the carrier gas to the shower head 24 through the raw material flow path 49, and this raw material gas is supplied together with the carrier gas to the shower head. 24 is introduced into the processing container 4.
When supplying the source gas of Cu as the second metal, the source gas is generated by evaporating Cu (hfac) ₂ as the solid source from the source tank 66 of the second source gas supply means 42. While controlling the flow rate of the raw material gas together with the carrier gas, the inside of the raw material flow path 68 is pumped and supplied to the shower head 24, and the raw material gas is introduced into the processing container 4 from the shower head 24 together with the carrier gas.

In addition, the reducing gas supply means 44 supplies H ₂ gas, which is a reducing gas, to the reducing gas passage 84 while controlling the flow rate of the H ₂ gas. During the film forming process, the evacuation system 12 is continuously driven to evacuate the inside of the processing container 4 and maintain a predetermined pressure. The wafer 14 on the mounting table 18 is heated by the heating unit 22. Heating is maintained at a predetermined temperature. Further, the plasma forming means 30 applies high-frequency power between the shower head 24 that is the upper electrode and the mounting table 18 that is the lower electrode, and generates plasma in the processing container 4 as necessary. The introduced gas is activated.

FIG. 4A shows the supply timing of each gas when forming a Ti film as the alloy seed film in the alloy seed film forming step. Here, the Ti film is formed for each layer at an atomic level thickness. A so-called ALD (Atomic Layer Deposition) method is performed. That is, an intermittent film-forming method is performed in which TiCl ₄ gas as a source gas and H ₂ gas as a reducing gas are alternately supplied at different timings to form a film. In this case, purging is performed between the supply timing of the source gas and the supply timing of the reducing gas in order to eliminate the residual gas in the processing container 4. At the time of this purge, all the gas supply may be stopped and only the evacuation may be continuously performed, or the supply of the source gas and the reducing gas is stopped while the evacuation is continuously performed. The inert gas may be supplied.

Here, plasma is generated (turned ON) only when the reducing gas H ₂ gas is supplied, and the H ₂ gas is activated so that the reaction can be promoted even when the wafer temperature is low. . As a result, the source gas adhering to the wafer surface when the source gas is supplied is reduced by introducing the H ₂ gas, and the Ti film having the atomic level as described above is deposited. In the illustrated example, two cycles of film formation are performed, and this cycle is repeated until a required film thickness is obtained. Generally, about 1 to 10 cycles are performed. In this case, the film thickness formed in one cycle is about 1 to 10 mm. For example, one supply period T1 of TiCl ₄ gas, one supply period T2 of H ₂ gas, and one purge period T3 are about 0.5 to 5 seconds, about 0.5 to 10 seconds, and 0.5 About 10 sec. Regarding the process conditions at this time, the process temperature is about 100 to 400 ° C., and the process pressure is about 13.3 to 1330 Pa (0.1 to 10 Torr).

FIG. 4B shows the supply timing of each gas when forming a Cu film as a base material film in the base material film forming step. Here, the Cu film is formed for each layer at an atomic level thickness. A so-called ALD (Atomic Layer Deposition) method is performed. That is, an intermittent film formation method is performed in which Cu (hfac) ₂ gas, which is a source gas, and H ₂ gas, which is a reducing gas, are alternately supplied at different timings to form a film. In this case, purging is performed between the supply timing of the source gas and the supply timing of the reducing gas in order to eliminate the residual gas in the processing container 4. At the time of this purge, all the gas supply may be stopped and only the evacuation may be continuously performed, or the supply of the source gas and the reducing gas is stopped while the evacuation is continuously performed. The inert gas may be supplied.

Here, plasma is generated (turned ON) only when the reducing gas H ₂ gas is supplied, and the H ₂ gas is activated so that the reaction can be promoted even when the wafer temperature is low. . As a result, the source gas adhering to the wafer surface when the source gas is supplied is reduced by introducing the H ₂ gas, and the Cu film having the atomic level as described above is deposited. In the illustrated example, many cycles of film formation are performed, and this cycle is repeated until a required film thickness is obtained. Generally, about several tens to several hundreds of cycles are performed. In this case, the film thickness formed in one cycle is about 1 to 2 mm. Further, for example, one supply period X1 of Cu (hfac) ₂ gas, one supply period X2 of H ₂ gas and one purge period X3 are about 0.5 to 5 seconds, about 0.5 to 10 seconds, and It is about 0.5 to 10 seconds. Regarding the process conditions at this time, the process temperature is about 100 to 400 ° C., and the process pressure is about 13.3 to 1330 Pa (0.1 to 10 Torr).

Then, when the alloy seed film forming step and the base material film forming step as described above are repeated once or alternately three times, a laminated structure as shown in FIG. 3 is completed. During the film formation, since the wafer itself is also heated to about 100 to 400 ° C., as described above, thermal diffusion of metal atoms occurs, and the entire alloy layer 100 is finally alloyed. , 102 (see FIG. 3) will be manufactured. Here, the number of laminated layers of the alloy seed film 104 and the base material film 106 is not limited to one or three, and it is sufficient to stack the necessary number as described above.
Further, when a plurality of layers of the alloy seed film 104 and the base material film 106 are formed as shown in FIG. 3B, the thicknesses of the same film type may be changed. For example, in FIG. 3B, the first-layer base material film 106 is formed with a thickness of 30 mm, and the second-layer base material film 106 is formed with a thickness of 90 mm, which is three times that thickness. You may do it.

Here, the film formation was actually performed as described above and the evaluation was performed, and the evaluation result will be described.
Here, the element concentration of the wafer and the alloy layer when the film formation as described above was performed directly on the surface of the silicon wafer was measured using XPS. FIG. 5 is a graph showing the concentration distribution of each element in the thickness direction of the silicon wafer at that time. In FIG. 5, the horizontal axis indicates the sputtering time, and the wafer surface is gradually scraped in the thickness direction by sputtering, and the concentration of each element at that time is shown. That is, the sputtering time corresponds to the dimension in the film thickness direction. Here, the respective concentrations of Si, Cu and Ti are shown. As is clear from the figure, the Ti concentration is considerably high in the boundary portion with the silicon wafer, and Ti is sufficiently reduced in the direction of decreasing the film thickness. It can be confirmed that the thermal diffusion has resulted in a certain Ti concentration.

In this case, after the thin film laminated structure as described above is manufactured, an annealing process for heating the entire wafer to a predetermined temperature may be performed. According to this, diffusion of Ti element can be performed more reliably.
As described above, since the Ti concentration can be locally increased at the boundary portion between the alloy layer and the wafer surface, the adhesion to the underlying wafer surface can be enhanced. Further, Ti element can be sufficiently thermally diffused and distributed over the entire laminated structure, that is, the entire alloy layers 100 and 102.

In addition, since the method of the present invention is performed by so-called ALD film formation without using the sputter film formation as in the conventional method, the step coverage can be sufficiently increased.
In the above embodiment, the case of using so-called ALD film formation in which film formation is performed by alternately supplying a so-called source gas and a reducing gas alternately is described, but the present invention is not limited to this. The film may be formed by a film. In this case, plasma CVD film formation using plasma or thermal CVD film formation without using plasma may be performed. This CVD film formation is a continuous film formation method in which a raw material gas and a reducing gas are simultaneously supplied into a processing container to continuously form a film.

  FIG. 6 is a timing chart showing the supply timing of each gas when a thin film laminated structure is manufactured by plasma CVD film formation. FIG. 6A shows a timing chart of the alloy seed film forming step, and FIG. 6B shows a timing chart of the base material film forming step. As is clear from FIG. 6, the source gas and the reducing gas are supplied simultaneously, and plasma is generated in synchronization therewith, and a Ti film and a Cu film are formed by plasma CVD. Since the Cu film is thicker, the film formation time in FIG. 6B is longer than that in the case of the Ti film in FIG. 6A. For example, the alloy seed film forming process takes 10 to 20 seconds. The base material film forming step is performed for about 200 to 2000 seconds. In this case, since the CVD film formation is used, the film formation rate is increased, so that not only the throughput can be improved, but also the embedding characteristics can be improved and the step coverage can be further improved.

A thin film laminated structure may be formed by combining the ALD film formation and the CVD film formation. For example, the alloy seed film formation step may be performed by ALD film formation, and the base material film formation step may be performed by CVD film formation.
In addition, the alloy seed film forming step and the base material film forming step are performed in the same processing container, that is, in the same film forming apparatus. However, the present invention is not limited to this. The wafers can be transported between a plurality of film forming apparatuses without being exposed to the atmosphere, and the alloy seed film forming process and the base material film forming process are respectively performed by different dedicated film forming apparatuses. You may make it perform.

In the above embodiment, TiCl ₄ was used as a raw material containing Ti metal, but the present invention is not limited to this. TiF ₄ (titanium tetrafluoride), TiBr ₄ (titanium tetrabromide), TiI ₄ (titanium tetraiodide) Ti [N (C ₂ H ₅ CH ₃ ] ₄ (TEMAT) (tetrakisethylmethylaminotitanium), Ti [N (CH ₃ ) ₂ ] ₄ (TDMAT) (tetrakisdimethylaminotitanium), Ti [N (C ₂ H ₅ ) ₂ ] ₄ (TDEAT) (tetrakisdiethylaminotitanium) or the like can be used.

In this embodiment, the case where Ti is used as the first metal that is an alloy type has been described as an example. However, the present invention is not limited to this. For example, Ti, Sn, W, Ta, Mg, In, Al, Ag, One metal selected from the group consisting of Co, Nb, B, V, and Mn can be used.
In this embodiment, the case where Cu is used as the second metal as the base material has been described as an example. However, the present invention is not limited to this. For example, one selected from the group consisting of Cu, Ag, Au, and W is used. Metal can be used.
Furthermore, in this embodiment, the case where H ₂ gas is used as the reducing gas has been described as an example. However, the present invention is not limited to this. For example, H ₂ , NH ₃ , N ₂ , N ₂ H ₄ [ One or more gases selected from the group consisting of hydrazine], NH (CH ₃ ) ₂ [ethylamine], N ₂ H ₃ CH [methyl diazene], N ₂ H ₃ CH ₃ [methyl hydrazine] can be used.
Furthermore, although a semiconductor wafer has been described as an example of the object to be processed here, the present invention is not limited to this, and a glass substrate, an LCD substrate, or the like can be used.

It is a schematic block diagram which shows an example of the film-forming apparatus which concerns on this invention. It is process drawing which shows the flow of this invention method. It is sectional drawing which shows an example of the laminated structure of a thin film. It is a timing chart which shows the timing of supply of each gas. It is a figure which shows the density | concentration profile of Ti and Cu of a wafer surface. It is a timing chart which shows the supply timing of each gas at the time of manufacturing the laminated structure of a thin film by plasma CVD film-forming.

Explanation of symbols

2 Film deposition apparatus 4 Processing container 12 Vacuum exhaust system 14 Semiconductor wafer (object to be processed)
18 Mounting table 22 Heating means 24 Shower head (gas introduction means)
30 Plasma forming means 34 High frequency power supply 40 First raw material gas supply means 42 Second raw material gas supply means 44 Reducing gas supply means 46 Liquid raw material (first metal)
64 Liquid raw material (second metal)
94 Control means 96 Storage medium 104 Alloy seed film 106 Base material film

Claims (15)

In a method for forming a laminated structure of thin films by depositing a plurality of thin films on the surface of an object to be processed in a processing container that is evacuated,
An alloy seed film forming step of forming an alloy seed film made of the first metal using a source gas containing the first metal as an alloy seed and a reducing gas, and a base material different from the first metal The base material film forming step of forming the base material film made of the second metal thicker than the alloy seed film using the source gas containing the second metal and the reducing gas is alternately performed at least once each. A method for forming a laminated structure of thin films.   In the alloy seed film forming step, an intermittent film forming method in which film formation is performed by intermittently supplying the source gas containing the first metal and the reducing gas into the processing vessel at different timings; The film forming method is performed by any one of a continuous film forming method in which a source gas containing a metal and a reducing gas are simultaneously supplied into the processing vessel to continuously form a film. Item 8. A method for forming a laminated structure of thin films according to Item 1.   In the base material film forming step, an intermittent film forming method in which a source gas containing the second metal and a reducing gas are intermittently supplied into the processing container at different timings to form a film; The film forming method is performed by any one of a continuous film forming method in which a source gas containing a metal and a reducing gas are simultaneously supplied into the processing vessel to continuously form a film. Item 8. A method for forming a laminated structure of thin films according to Item 1.   The annealing process for heating the object to be processed to a predetermined temperature is performed after the alloy seed film forming process and the base material film forming process are alternately performed at least once. A method for forming a laminated structure of thin films according to any one of 1 to 3.   5. The method for forming a laminated structure of thin films according to claim 1, wherein the alloy seed film forming step and the base material film forming step are performed in the same processing container.   5. The method for forming a laminated structure of thin films according to claim 1, wherein the alloy seed film forming step and the base material film forming step are alternately performed in different processing vessels.   The thickness of one layer of the alloy seed film is in the range of 1 to 200 mm, and the thickness of one layer of the base material film is in the range of 5 to 500 mm. A method for forming a laminated structure of thin films according to any one of the above.   The first metal is one metal selected from the group consisting of Ti, Sn, W, Ta, Mg, In, Al, Ag, Co, Nb, B, V, and Mn. Item 8. A method for forming a laminated structure of thin films according to any one of Items 1 to 7.   9. The method of forming a thin film laminated structure according to claim 1, wherein the second metal is one metal selected from the group consisting of Cu, Ag, Au, and W. The reducing gas is H ₂ , NH ₃ , N ₂ , N ₂ H ₄ [hydrazine], NH (CH ₃ ) ₂ [ethylamine], N ₂ H ₃ CH [methyldiazene], N ₂ H ₃ CH ₃ [methyl hydrazine 10. The method for forming a laminated structure of thin films according to any one of claims 1 to 9, wherein the gas is one or more gases selected from the group consisting of: In the laminated structure of the thin film formed on the surface of the workpiece,
An alloy seed film made of a first metal formed using a source gas containing a first metal as an alloy seed and a reducing gas, and a second metal as a base material different from the first metal A thin film characterized in that one or more layers of a base metal film made of a second metal formed thicker than the alloy seed film by using a source gas and a reducing gas are alternately stacked. Laminated structure.   The thickness of one layer of the alloy seed film is in the range of 1 to 200 mm, and the thickness of one layer of the base material film is in the range of 5 to 500 mm. Thin film stack structure. In a film forming apparatus for depositing a thin film on the surface of an object to be processed,
A processing vessel that can be evacuated;
A mounting table for mounting the object to be processed;
Heating means for heating the object to be processed;
Gas introduction means for introducing gas into the processing vessel;
A first source gas supply means for supplying a source gas containing a first metal as an alloy species to the gas introduction means;
Second source gas supply means for supplying a source gas containing a second metal as a base material to the gas introduction means;
Reducing gas supply means for supplying a reducing gas to the gas introducing means;
Control means for operating the entire apparatus and controlling the alloy seed film made of the first metal and the base material film made of the second metal to alternately form one or more layers each;
A film forming apparatus comprising:   The film forming apparatus according to claim 13, further comprising plasma forming means for generating plasma in the processing container. When forming a laminated structure of thin films by depositing a plurality of thin films on the surface of an object to be processed in a processing vessel that can be evacuated,
An alloy seed film forming step of forming an alloy seed film made of the first metal using a source gas containing the first metal as an alloy seed and a reducing gas, and a base material different from the first metal The base material film forming step of forming the base material film made of the second metal thicker than the alloy seed film using the source gas containing the second metal and the reducing gas is alternately performed at least once each. A storage medium for storing a program for controlling the film forming apparatus.

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