JP2006024667A - Process for fabricating semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress diffusion of metal employed in barrier metal into a porous low dielectric constant (p-lowk) film being formed porously. <P>SOLUTION: The process for fabricating a semiconductor device comprises a step for forming a p-lowk film on a substrate (S102); a step for supplying Ta[N(C<SB>2</SB>H<SB>5</SB>)<SB>2</SB>]<SB>5</SB>which causes attraction of a molecule (Ta-R1) having a hole on the surface side of the p-lowk film larger than the opening size at a position coupled with the hole on the inner side of the p-lowk film to the surface of the p-lowk film (S106); a step for supplying NH<SB>3</SB>reacting on the molecule (Ta-R1) and forming a TaN film (S110); a step for supplying TaCl<SB>5</SB>which causes attraction of a molecule (Ta-R2) smaller than the opening size (S114); and a step for supplying NH<SB>3</SB>reacting on the molecule (Ta-R2) and forming a TaN film furthermore (S120). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a ULSI (Ultra large scale) having Cu wiring.
integrated circuit) relates to a device manufacturing method.

  Cu wiring having low resistance and high electromigration (EM) resistance is expected as a highly reliable material for highly integrated and miniaturized LSI wiring.

  In particular, recently, in order to achieve high-speed performance of LSIs, there has been a movement to replace the wiring technology from conventional aluminum (Al) alloy to low resistance Cu or Cu alloy (hereinafter collectively referred to as Cu). . Since Cu is difficult to finely process by the dry etching method frequently used in the formation of Al alloy wiring, Cu film is deposited on the insulating film subjected to the groove processing, and other than the portion embedded in the groove A so-called damascene method, in which the Cu film is removed by chemical mechanical polishing (CMP) to form a buried wiring, is mainly employed. In general, a Cu film is formed by forming a thin seed layer by sputtering or the like and then forming a laminated film having a thickness of about several hundreds of nanometers by electrolytic plating.

Further, recently, it has been studied to use a low dielectric constant (low-k) film having a low relative dielectric constant as an interlayer insulating film. That is, by using a low-k film having a relative dielectric constant k of 3.5 or less from a silicon oxide film (SiO ₂ ) film having a relative dielectric constant k of about 4.2, parasitic capacitance between wirings is reduced. It has been tried. A method of manufacturing a semiconductor device having a multilayer wiring structure in which such a low-k film and a Cu wiring are combined is as follows.

FIG. 20 is a process cross-sectional view illustrating a method of manufacturing a semiconductor device having a multilayer wiring structure in which a conventional low-k film and Cu wiring are combined.
In FIG. 20, a method for forming a device portion or the like is omitted.
In FIG. 20A, a first insulating film 221 is formed on a silicon substrate 200 by a method such as CVD (chemical vapor deposition).
In FIG. 20B, a groove structure (opening H) for forming a Cu metal wiring or a Cu contact plug is formed in the first insulating film 221 by a photolithography process and an etching process.
In FIG. 20C, a barrier metal film 240, a Cu seed film, and a Cu film 260 are formed in this order on the first insulating film 221, and annealed at a temperature of 150 ° C. to 400 ° C. for about 30 minutes.
In FIG. 20D, the Cu film 260 and the barrier metal film 240 are removed by CMP and planarized to form a Cu wiring in the opening H that is a groove.
In FIG. 20E, a second insulating film 281 is formed after the surface of the Cu film 260 is subjected to reducing plasma treatment.
Furthermore, when forming multilayer Cu wiring, it is common to repeat these processes and to laminate. Here, most of the first insulating film 221 and the second insulating film 281 are low-k films.

In next-generation devices, the use of a low dielectric constant film as an interlayer insulating film, in particular, a low dielectric constant film having pores is being studied in order to lower the dielectric constant. In other words, the development of low-k film materials having a relative dielectric constant k of 2.5 or less has been promoted, and many of these are porous materials having pores in the material. As Cu wiring is further miniaturized in the future, it is essential to reduce the thickness of the barrier metal, which has a higher resistance than Cu. In order to form an ultra-thin barrier metal film, atomic layer vapor deposition (ALD: Atomic Layer) is being studied.
There is a Deposition method (for example, see Non-Patent Documents 1 and 2). This method is a method of performing film formation at the atomic layer level by alternately supplying source gases.

FIG. 21 is a gas supply flow diagram showing an example of barrier metal film formation by the ALD method.
First, a tantalum (Ta) raw material is supplied. For example, it will be described with reference to tantalum chloride (TaCl _5). At this time, a certain amount or more is not adsorbed due to the self-limiting effect. Next, purging is performed with argon (Ar). Subsequently, by supplying ammonia (NH ₃ ), tantalum nitride (TaN) as a barrier metal is formed. Finally, purge is performed with Ar. This series of operations is defined as one cycle, and film formation is performed by repeating a cycle corresponding to the required film thickness.
FIG. 22 is a conceptual diagram for explaining how a TaN film is formed in the ALD method.
In FIG. 22A, TaR20 (Ta compound) is adsorbed on the substrate 10 by supplying TaR20 (Ta compound). Further, TaR 20 that is not adsorbed floats around the base 10.
In FIG. 22B, by supplying Ar, floating TaR 20 is replaced (purged).
In FIG. 22C, by supplying NH ₃ , TaR 20 adsorbed on the substrate 10 is reduced to form a TaN film 22.

Other techniques related to the ALD method include a technique in which a plurality of substrates are simultaneously loaded into an ALD reactor (see Patent Document 1), and a technique in which the same raw material is repeatedly supplied with a purge or the like interposed during ALD film formation (patent) Reference 2), when forming a metal oxide film, after supplying a reaction product that does not contain a hydroxyl group, supply a reaction product that contains a hydroxyl group, thereby suppressing the generation of by-products of the hydroxyl group (Refer to Patent Document 3), a technique for performing ALD film formation while rotating the substrate (refer to Patent Document 4), a technique in which a barrier metal film is a laminated film of a metal nitride film and a copper film (refer to Patent Document 5), ALD A technique for supplying radicals during film formation (see Patent Document 6) is disclosed.
Japanese Patent Laid-Open No. 2002-367992 JP 2000-54134 A JP 2001-152339 A JP 2001-254181 A JP 2002-329680 A Special Table 2002-539326 “Atomic layerdeposition of metal and nitride thin films: Current research efforts and applications for semiconductor device processing”, J. Vac. Sci. Technol. B21 (6), 2003, p2231-2261 “Atomiclayer deposition for nanoscale Cu metallization”, AdvancedMetallization Conference 2003 Conference Proceedings AMC XIX 2004 MaterialsResearch Society p713-722

When the barrier metal film is formed on the porous low dielectric constant (p-lowk) film by using the ALD method, the metal used for the barrier metal is diffused into the base film. For example, when performing TaD ALD film formation using TaCl ₅ and NH ₃ described above as raw materials, porous porous methylsilsesquioxane (p-MSQ) is used as the p-lowk material for the underlayer Causes diffusion of Ta metal into the p-MSQ. For this reason, the barrier property of TaN as a finished varimetal is reduced.

  An object of the present invention is to overcome the above-described problems and to suppress diffusion of a metal used as a barrier metal into a porous low dielectric constant (p-lowk) film formed in a porous shape.

A method for manufacturing a semiconductor device of the present invention includes:
A porous film forming step in which a plurality of pores are formed, and the pores formed on the surface side are connected to the internal pores to form a porous film that opens to the inside on the substrate;
A first adsorption step for adsorbing, on the porous membrane surface, first molecules larger than the opening size at a connection position where the pores formed on the porous membrane surface side are connected to the pores on the porous membrane inner side. When,
Supplying a first reactive species that reacts with the first molecule, and forming a first reaction product film on the porous film surface;
A second adsorption step for adsorbing a second molecule smaller than the opening size on the surface of the first reaction product film;
Supplying a second reactive species that reacts with the second molecule, and forming a second reaction product film on the surface of the first reaction product film;
It is provided with.

  As will be described later, the diffusion of the metal used for the barrier metal into the p-lowk film is such that when the metal raw material is adsorbed on the surface of the p-lowk film as a molecule of a predetermined size, Since the holes formed on the surface side of the p-lowk film are smaller than the opening size at the connecting position where the holes are connected to the holes inside the p-lowk film, the holes diffuse into the p-lowk film. Therefore, when the second reaction product film is formed using the second molecules smaller than the opening size, first, the first molecules larger than the opening size are adsorbed on the surface of the porous film. A state in which the opening surface at the connection position is closed by one molecule is formed, and a first reaction product film is formed. Then, the second reaction product film can be formed in a desired film thickness by adsorbing second molecules smaller than the opening size on the surface of the first reaction product film.

Here, in the first adsorption step, a metal organic compound is supplied as a raw material for the first molecule,
In the second adsorption step, a metal inorganic compound is supplied as a raw material for the second molecule.

  Even when the second reaction product film is formed using a metal inorganic compound having a small molecular size and easily diffusing as a raw material, first, a metal organic compound having a large molecular size is supplied as a raw material, and the first molecule is supplied to the porous film. By adsorbing to the surface, it is possible to form a state in which the opening surface of the porous film is closed.

  Alternatively, in the first adsorption step, a raw material of the same type as that used in the second adsorption step is supplied as the raw material of the first molecule, and the substrate temperature is lower than the substrate temperature in the second adsorption step. It is also effective to adsorb the first molecule.

  Even when the same kind of raw material is used, first, the first molecule size is made larger than the second molecule size by adsorbing the first molecule at a substrate temperature lower than the substrate temperature in the second adsorption step. It can be adsorbed on the surface of the porous membrane in a large state.

  Here, it is particularly effective when a low dielectric constant film having a relative dielectric constant of 2.5 or less is used as the porous film.

For the porous film having an opening size of 0.6 nm or less, pentadimethyltantalum (Ta [N (CH ₃ ) ₂ ] ₅ ) is used as a raw material for the first molecule in the first adsorption step. It is characterized by that.

By using Ta [N (CH ₃ ) ₂ ] ₅ as a raw material for the first molecule, the molecular size adsorbed on the surface of the porous film can be 0.6 nm or more, and the opening is 0.6 nm or less. The internal diffusion of Ta can be suppressed with respect to the size porous film.

In the first adsorption step, pentadiethyl tantalum (Ta [N (C ₂ H ₅ ) ₂ ] ₅ ) is used as the raw material for the first molecule for the porous film having an opening size of 0.7 nm or less. It is used as.

By using Ta [N (C ₂ H ₅ ) ₂ ] ₅ as a raw material for the first molecule, the molecular size adsorbed on the porous film surface can be 0.7 nm or more, and 0.7 nm or less. It is possible to suppress internal diffusion of Ta with respect to a porous film having an opening size of.

Tantalum chloride (TaCl ₅ ) is used as a raw material for the first and second molecules in the first and second adsorption steps for the porous film having an opening size of 0.3 nm or less. And

When TaCl ₅ is used as a raw material for the first and second molecules, in the first adsorption step, the first molecule is adsorbed at a lower substrate temperature than in the second adsorption step. The molecular size adsorbed on the surface can be 0.3 nm or more, and internal diffusion of Ta can be suppressed with respect to a porous film having an opening size of 0.3 nm or less.

A method for manufacturing a semiconductor device of the present invention includes:
A porous film forming step of forming a porous film on the substrate;
A pentadimethyl tantalum supply step of controlling the substrate temperature to a temperature lower than 250 ° C. and supplying pentadimethyl tantalum (Ta [N (CH ₃ ) ₂ ] ₅ ) onto the substrate on which the porous film is formed;
A reactive species supplying step of supplying reactive species that react with Ta [N (CH ₃ ) ₂ ] ₅ after supplying Ta [N (CH ₃ ) ₂ ] ₅ ;
It is provided with.

By supplying Ta [N (CH ₃ ) ₂ ] ₅ at a temperature lower than the normal film formation temperature, which is lower than 250 ° C., the molecular size adsorbed on the porous film can be further increased. It is possible to suppress internal diffusion of Ta with respect to the material film. Then, a Ta-based film can be formed on the porous film by reacting with the reactive species.

A method for manufacturing a semiconductor device of the present invention includes:
A porous film forming step of forming a porous film on the substrate;
A pentadiethyl tantalum supply step of controlling the substrate temperature to a temperature lower than 250 ° C. and supplying pentadiethyl tantalum (Ta [N (C ₂ H ₅ ) ₂ ] ₅ ) onto the substrate on which the porous film is formed; ,
A reactive species supplying step of supplying reactive species that react with Ta [N (C ₂ H ₅ ) ₂ ] ₅ after supplying Ta [N (C ₂ H ₅ ) ₂ ] ₅ ;
It is provided with.

By supplying the _{Ta [N (C 2 H 5} ) 2] 5 at a temperature lower than 250 ° C. at a temperature lower than the normal deposition temperature, it is possible to further increase the molecular size to adsorb to the porous membrane In addition, it is possible to suppress internal diffusion of Ta with respect to the porous film. Then, a Ta-based film can be formed on the porous film by reacting with the reactive species.

A method for manufacturing a semiconductor device of the present invention includes:
A porous film forming step of forming a porous film on the substrate;
A tantalum chloride supply step of controlling the substrate temperature to be lower than 300 ° C. and supplying tantalum chloride (TaCl ₅ ) onto the substrate on which the porous film is formed;
TaCl ₅ after the supply to a reaction species supply step of supplying a reactive species that reacts with TaCl _5,
It is provided with.

By supplying TaCl ₅ at a temperature lower than 300 ° C., which is a temperature lower than the normal film formation temperature, the molecular size adsorbed on the porous film can be further increased. Diffusion can be suppressed. Then, a Ta-based film can be formed on the porous film by reacting with the reactive species.

  According to the present invention, the state in which the opening surface at the coupling position is closed with the initially adsorbed molecules is formed, so that internal diffusion to the porous film can be suppressed. In addition, by selecting a raw material in accordance with the opening size, it is possible to respond widely according to the properties of the porous membrane. The molecular size adsorbed on the porous membrane can be controlled in accordance with the opening size. Since the molecular size adsorbed on the porous membrane can be controlled, it is possible to cope with a wide range according to the properties of the porous membrane.

Embodiment 1 FIG.
In the first embodiment, Ta [N (C ₂ H ₅ ) ₂ ] ₅ is used as a metal raw material, and a TaN film as an barrier metal film is ALD formed on a p-MSQ as a porous low dielectric constant film. Will be explained.
FIG. 1 is a flowchart showing the main part of the semiconductor device manufacturing method according to the first embodiment.
In FIG. 1, in the present embodiment, a p-lowk film forming step (S102) for forming a porous low dielectric constant (p-lowk) film using a porous low dielectric constant insulating material on a substrate, an opening forming step of forming an opening (S104), as the first barrier metal film forming _{step, Ta [N (C 2 H} 5) 2] 5 for supplying _{Ta [N (C 2 H 5} ) 2] ₅ supply step (S106), hydrogen (H ₂ ) supply step (S108), NH ₃ supply step (S110), H ₂ supply step (S112), and TaCl ₅ is supplied as the second barrier metal film forming step. A series of steps of a TaCl ₅ supply step (S114), an H ₂ supply step (S116), an NH ₃ supply step (S118), and an H ₂ supply step (S120) are performed.
The first barrier metal film forming step includes a Ta [N (C ₂ H ₅ ) ₂ ] ₅ supply step (S106), a hydrogen (H ₂ ) supply step (S108), an NH ₃ supply step (S110), and an H ₂ supply. The step (S112) is repeated as one cycle. In the second barrier metal film forming step, the TaCl ₅ supply step (S114), the H ₂ supply step (S116), the NH ₃ supply step (S118), and the H ₂ supply step (S120) are repeated as one cycle. Then, after forming a desired TaN film, copper (Cu) as a conductive material is deposited by a physical vapor deposition (PVD) method and a plating method to form a Cu wiring.

FIG. 2 is a diagram for explaining a state of molecules adsorbed on the porous low dielectric constant film.
Many pores are formed in the porous low dielectric constant (p-lowk) film. These holes are connected to each other to form a porous extending from the inside to the surface. At the connecting position (hole connecting portion) where the plurality of holes are connected, an opening surface smaller than the hole size is generally formed. However, as shown in FIG. During film formation, the supplied metal source gas becomes molecules (Ta-R2) and is adsorbed on the p-lowk film. At this time, if the size of the molecule is smaller than the opening size of the opening surface at the connecting position (hole connecting portion size), the molecules diffuse into the p-lowk film. Since Ta is bonded to such molecules, Ta diffusion occurs. On the other hand, as shown in FIG. 2B, when a barrier metal film is formed by the ALD method to be described later, the supplied metal source gas becomes molecules (Ta-R1) and is adsorbed on the p-lowk film. At this time, if the size of the molecule is larger than the opening size of the opening surface at the connection position, the opening surface is blocked and no further diffusion into the p-lowk film occurs. In this embodiment mode, it can be seen that an ALD film may be formed using molecules (Ta-R1) larger than the opening size.

FIG. 3 is a process cross-sectional view illustrating a process of the semiconductor device manufacturing method according to the first embodiment.
FIG. 3 shows from the SiC film formation step (S102) not shown in FIG. 1 to the opening formation step (S104) in FIG. Subsequent steps will be described later.

First, the step of forming an interlayer insulating film (not shown) other than the porous low-k film forming step (S102) in FIG. 1 on the substrate and the opening forming step (S104) of FIG. 1 will be described.
In FIG. 3A, as a SiC film forming step, a base silicon carbide (SiC) film having a thickness of 50 nm using SiC is deposited on the substrate 200 by a CVD method to form a SiC film 212. Here, the film is formed by chemical vapor deposition (CVD method), but other methods may be used. The SiC film 212 has a function as a diffusion prevention film. The SiC film 212 also has a function as an etching stopper. Since it is difficult to generate the SiC film, a silicon carbonate (SiOC) film may be used instead of the SiC film. Alternatively, a silicon carbonitride (SiCN) film or a silicon nitride (SiN) film can be used. As the substrate 200, for example, a substrate such as a silicon wafer having a diameter of 300 mm is used. A device portion such as a metal wiring or a contact plug may be formed on the base body 200. Alternatively, other layers may be formed.

In FIG. 3B, as a p-lowk film forming step, a low dielectric using a porous insulating material on the SiC film 212 formed by the SiC insulating film forming step formed on the substrate 200. A p-lowk film 220 to be a rate insulating film is formed with a thickness of 300 nm. For use as a semiconductor device, about 150 nm to 300 nm is more desirable, but the present invention is not limited to this and may be about 100 nm to 1000 nm. Here, by forming the p-lowk film 220, an interlayer insulating film having a low relative dielectric constant can be obtained. As a material of the p-lowk film 220, for example, porous porous methylsilsesquioxane (MSQ) can be used. As the formation method, for example, an SOD (spin on selective coating) method in which a thin film is formed by spin-coating a solution and performing heat treatment can be used. Here, the spinner was formed at a rotation speed of 900 min ⁻¹ (900 rpm). This wafer was baked on a hot plate at a temperature of 250 ° C. in a nitrogen atmosphere, and finally cured on a hot plate at a temperature of 450 ° C. in a nitrogen atmosphere for 10 minutes. A porous insulating film having predetermined physical properties can be obtained by appropriately adjusting the material and forming conditions of porous MSQ (p-MSQ). The hole connecting part size (opening size) in the hole connecting part can also be formed with good reproducibility by using the same kind of raw material and manufacturing method. For example, here, a p-MSQ having a hole connecting portion size of 0.6 nm is formed.
As for the composition of the aforementioned p-MSQ film, the silicon concentration is preferably 20% to 40%, the carbon concentration is 10% to 30%, and the oxygen concentration is 40% to 60%. The low dielectric constant insulating film is preferably a p-lowk film having a relative dielectric constant k of 2.6 or less. For example, in addition to p-MSQ, other porous low dielectric constant films such as a porous HSQ (Hydrogen Silsesquioxane) film and a porous aromatic polymer film may be used. These are desirable for miniaturization of semiconductor devices. The p-lowk film may be formed by a CVD method.

Then, as a He plasma treatment step, the surface of the p-lowk film 220 is surface-modified by helium (He) plasma irradiation in a CVD apparatus. By modifying the surface by He plasma irradiation, the adhesion between the p-lowk film 220 and a CVD-SiO ₂ film 222 as a cap insulating film to be described later formed on the p-lowk film 220 can be improved. it can. The gas flow rate was 1.7 Pa · m ³ / s (1000 sccm), the gas pressure was 1000 Pa, the high frequency power was 500 W, the low frequency power was 400 W, and the temperature was 400 ° C. When the cap CVD film is formed on the p-lowk film, it is effective to improve the adhesion with the cap CVD film by performing plasma treatment on the surface of the p-lowk film. As types of plasma gas, ammonia (NH ₃ ), nitrous oxide (N ₂ O), hydrogen (H ₂ ), He, oxygen (O ₂ ), silane (SiH ₄ ), argon (Ar), nitrogen (N ₂ ) Among these, He plasma is particularly effective because it causes little damage to the p-lowk film. The plasma gas may be a mixture of these gases. For example, it is effective to use He gas mixed with other gases.

In FIG. 3 (c), as the SiO ₂ film forming step is an example of the cap insulating film forming step, after the He plasma treatment, as a cap insulating film, a SiO ₂ on p-low k film 220 by the CVD method By depositing the film to a thickness of 50 nm, an SiO ₂ film 222 covering the p-lowk film 220 is formed on the p-lowk film 220. By forming the SiO ₂ film 222, it is possible to protect the p-lowk film 220 that cannot be directly lithography, and to form a pattern in the p-lowk film 220. Cap CVD films, which are cap insulating films by CVD, include SiO ₂ films, SiC films, SiOC films, SiCN films, etc., but from the viewpoint of reducing damage, SiO ₂ films are excellent and from the viewpoint of lowering the dielectric constant. The SiOC film is superior to the SiC film or the SiCN film from the viewpoint of improving the breakdown voltage. Furthermore, a laminated film of SiO ₂ film and SiC film, a laminated film of SiO ₂ film and SiCO film, or a laminated film of SiO ₂ film and SiCN film can be used. Furthermore, a part or all of the cap CVD film may be removed by CMP in a conductive material polishing step described later. The dielectric constant can be further reduced by removing the cap film. The thickness of the cap insulating film is preferably 10 nm to 150 nm, and 10 nm to 50 nm is effective in reducing the effective dielectric constant. Here, a CVD film by a CVD method is used as the cap insulating film, but an SOD film may be used.

In FIG. 3D, as the opening forming process, the opening 150 which is a wiring groove structure for producing a damascene wiring by a lithography process and a dry etching process is formed by using an SiO ₂ film 222, a p-lowk film 220, and a base SiC film. 212. An exposed SiO ₂ film 222 and a p-lowk film positioned below the exposed SiO ₂ film 222 with respect to the substrate 200 on which the resist film is formed on the SiO ₂ film 222 through a lithography process such as a resist coating process and an exposure process (not shown). 220 may be removed by anisotropic etching using the underlying SiC film 212 as an etching stopper, and then the underlying SiC film 212 may be etched to form the opening 150. By using the anisotropic etching method, the opening 150 can be formed substantially perpendicular to the surface of the substrate 200. For example, as an example, the opening 150 may be formed by a reactive ion etching method.

FIG. 4 is a process sectional view showing a process of the method for manufacturing the semiconductor device in the first embodiment.
FIG. 4 shows from the Ta [N (C ₂ H ₅ ) ₂ ] ₅ supply step (S106) in FIG. 1 to the planarization step not shown in FIG.

In FIG. 4A, as a barrier metal film forming step, a barrier metal film 240 using a barrier metal material is formed on the surface in the opening and the surface of the SiO ₂ film 222 by the ALD method.

Here, a tantalum nitride (TaN) film is formed as the barrier metal film. First, pentadiethyl tantalum (Ta [N (C ₂ H ₅ ) ₂ ] ₅ ) is used as a metal raw material for forming the first barrier metal film, which is an example of a reactive species that reacts with the metal raw material, Ammonia (NH ₃ ) is used as the reducing gas for the metal raw material, and hydrogen (H ₂ ) is used as the purge gas. By using H ₂ as the purge gas, the following reactivity can be enhanced. Furthermore, since H ₂ can increase the purity, it is suitable for high-purity film formation.
FIG. 5 is a diagram showing a supply flow of each gas in the TaN film formation step.
As a Ta [N (C ₂ H ₅ ) ₂ ] ₅ supply step, Ta [N (C ₂ H ₅ ) ₂ ] ₅ is supplied for 1 s. Thereafter, as an H ₂ supply step, H ₂ is supplied for 1 s and purged. Then, the NH ₃ supply process, the NH ₃ 1s supplies. Then, as the H ₂ supply step, H ₂ is supplied for 1 s and purged. This process is defined as one cycle, and 10 cycles are supplied at a film forming temperature of 300 ° C.

Molecules adsorbed on the surface of the p-lowk film 220 exposed on the inner side surface of the opening by using Ta [N (C ₂ H ₅ ) ₂ ] ₅ which is a metal organic compound at a film forming temperature of 300 ° C. (Ta-R1 in FIG. 2) The size can be 0.6 nm or more.

FIG. 6 is a diagram showing a schematic configuration of the ALD apparatus.
In FIG. 6, the substrate 10 that has been processed up to the previous step on the substrate 200 inside the chamber 600 is placed on a substrate holder (wafer stage) 610 controlled to a predetermined temperature. Install. Then, gas is supplied into the chamber 600 from above. Further, the vacuum pump 630 is evacuated so that the inside of the chamber 600 becomes a predetermined pressure. Solid Ta [N ((C ₂ H ₅ ) ₂ ] ₅ contained in the container 650 is heated to 50 to 70 ° C. The carrier is contained in the heated and melted Ta [N (C ₂ H ₅ ) ₂ ] ₅ . By supplying H ₂ gas as gas, Ta [N (C ₂ H ₅ ) ₂ ] ₅ gasified together with H ₂ can be supplied to the chamber 600 by a kind of bubbling method.

Here, the gas amounts of Ta [N (C ₂ H ₅ ) ₂ ] ₅ , H ₂ , and NH ₃ are 1.68 Pa · m ³ / s (1000 sccm), and the pressure inside the chamber 600 is 339 Pa (3 Torr). It was. Here, the amount of gas, _Ta for _{[N (C 2 H 5)} 2] 5, 0.5Pa · m 3 /s(300sccm)~1.68Pa · m 3 / s (1000sccm) is desirable. For ^{_{NH 3, 1.68Pa · m 3 /s(1000sccm)~3.36Pa}} · m 3 / s (2000sccm) is desirable. For _{H 2} is ^{purge, 1.68Pa · m 3 /s(1000sccm)~3.36Pa · m} 3 / s (2000sccm) is desirable. The film forming pressure is desirably 665 Pa (5 Torr) or less. The film forming temperature is preferably 250 to 300 ° C.

Further, hydrazine (H ₂ NNH ₂ ) or a hydrazine compound such as 1-1 dimethyl hydrazine or 1-2 dimethyl hydrazine may be used as a reducing gas for the metal raw material. By using hydrazine or a hydrazine compound, the reducing action can be made stronger than NH ₃ .

Furthermore, argon (Ar), nitrogen (N ₂ ), or He may be used as the purge gas. By using Ar, it can be made cheap and easy to handle.

Next, tantalum chloride (TaCl ₅ ) is used as a metal raw material for forming the second barrier metal film in the TaN film forming step, and the reducing gas for the metal raw material is an example of a reactive species that reacts with the metal raw material. As the purge gas, ammonia (NH ₃ ) is used, and hydrogen (H ₂ ) is used as the purge gas. By using TaCl ₅ as the metal raw material, the self-limiting performance can be improved. Further, by using TaCl ₅ , unlike the organic material, carbon (C) or the like does not remain inside the TaN film, and the TaN film can be highly purified. A device having a configuration similar to that shown in FIG. 6 may be used. Similarly, the solid TaCl ₅ contained in the container 650 is heated to 50 to 100 ° C. and warmed. By supplying _{H 2} gas as a carrier gas warmed melted TaCl _5, can be supplied to the chamber 600 of TaCl ₅ gasified with _{H 2} by a kind of bubbling method.
The supply flow of each gas in the second barrier metal film formation was as follows.
As a TaCl ₅ supply step, TaCl ₅ is supplied for 1 s. Thereafter, as an H ₂ supply step, H ₂ is supplied for 1 s and purged. Then, the NH ₃ supply process, the NH ₃ 2s supplies. Then, as the H ₂ supply step, H ₂ is supplied for 1 s and purged. This process is defined as one cycle, and 30 cycles are supplied at a film forming temperature of 350 ° C.

Even when TaCl ₅ which is a metal inorganic compound is used at a film forming temperature of 350 ° C., the size of the molecule (Ta-R2 in FIG. 2) is smaller than 0.6 nm, but the pores are already blocked by the first TaN film. Therefore, it is difficult for Ta to diffuse into the p-lowk film 220. In this state, a TaN film (second TaN film) is further formed on the first TaN film, and a TaN film having a desired film thickness can be formed. Here, a TaN film having a thickness of 2 nm was formed.

Here, the gas amounts of TaCl ₅ , H ₂ , and NH ₃ were 1.68 Pa · m ³ / s (1000 sccm), and the pressure inside the chamber 600 was 339 Pa (3 Torr). Here, the amount of gas, the ^{_{TaCl 5, 0.5Pa · m 3 /s(300sccm)~1.68Pa}} · m 3 / s (1000sccm) is desirable. For ^{_{NH 3, 1.68Pa · m 3 /s(1000sccm)~3.36Pa}} · m 3 / s (2000sccm) is desirable. For _{H 2} is ^{purge, 1.68Pa · m 3 /s(1000sccm)~3.36Pa · m} 3 / s (2000sccm) is desirable. The film forming pressure is desirably 665 Pa (5 Torr) or less. The film forming temperature is desirably 300 to 350 ° C.

Similarly, H ₂ NNH ₂ or a hydrazine compound such as 1-1 dimethylhydrazine or 1-2 dimethylhydrazine may be used as the reducing gas for the metal raw material. Further, the same is true in that Ar, N ₂ or He may be used as the purge gas.

FIG. 7 is a conceptual diagram for explaining an outline of an apparatus including a plurality of chambers.
In FIG. 7, the apparatus 500 has a plurality of chambers 510, 520, and 530. A wafer is set in the cassette chamber 550, and in the transfer chamber 540, a transfer robot transfers or unloads the wafer to each chamber. The process can be stabilized by performing the first barrier metal film formation and the second barrier metal film formation in the same apparatus capable of vacuum transfer. Further, since the processing is performed without exposing the wafer to the outside air, adhesion of particles can be prevented. For example, the first barrier metal film is formed in the chamber 510, and the second barrier metal film is formed in the chamber 520.

FIG. 8 is a diagram illustrating another schematic configuration example of the ALD apparatus.
In the apparatus shown in FIG. 6, the gas is supplied from the upper part of the chamber 600 regardless of the size of the substrate 10 and regardless of the gas traveling direction. As shown in FIG. It is more preferable that the gas is uniformly supplied from the shower head 620 to the entire surface of the base 10. Other configurations are the same as those in FIG.

  In FIG. 4B, an opening in which a barrier metal film 240 is formed by using a Cu thin film serving as a cathode electrode in a subsequent electrolytic plating process as a seed film 250 by a PVD method such as sputtering as a seed film forming process. The inner wall 150 and the surface of the substrate 200 are deposited (formed). Here, the seed film 250 is deposited to a thickness of 100 nm.

  In FIG. 4C, as a plating process, a Cu film 260 is deposited on the surface of the opening 150 and the substrate 200 by electrochemical growth such as electrolytic plating using the seed film 250 as a cathode electrode. Here, a Cu film 260 having a thickness of 500 nm is deposited, and after the deposition, annealing is performed at a temperature of 250 ° C. for 30 minutes.

In FIG. 4D, as a planarization step, the Cu film 260, the seed film 250, and the barrier metal film 240, which become a wiring layer as a conductive portion deposited on the surface of the SiO ₂ film 222 by CMP, are polished and removed. As a result, planarization is performed, and a buried structure to be a lower layer wiring as shown in FIG. 4D is formed.

As described above, Ta [N (C ₂ H ₅ ) ₂ ] ₅ and NH are formed on p-MSQ (hole connection portion size: 0.6 nm) using a low pressure CVD apparatus (here, ALD apparatus). ₃ and at a film forming temperature of 300 ° C., Ta [N (C ₂ H ₅ ) ₂ ] ₅ (1 s) → H ₂ (1 s) → NH ₃ (1 s) → H ₂ (1 s) as one cycle, Supply 10 cycles, then set the film-forming temperature to 350 ° C., and supply 30 cycles with TaCl ₅ (1 s) → H ₂ (1 s) → NH ₃ (2 s) → H ₂ (1 s) as one cycle. As a result of TEM observation, 2 nm of TaN was formed as a result of TEM (transmission electron microscope) observation, and no diffusion into the underlying porous MSQ was observed. Diffusion into the p-MSQ can be suppressed by forming an ALD-TaN film using Ta [N (C ₂ H ₅ ) ₂ ] ₅ which is larger than the hole connection portion size of the base p-MSQ. . Further, by using TaCl ₅ which has a large self-limiting effect and can be easily purified, it is possible to form a highly purified ALD-TaN film with high film thickness controllability.

Furthermore, as an example of the first adsorption step, Ta [ N (C ₂ H ₅ ) ₂ ] ₅ supply step, the first molecule larger than the opening size at the connection position where the pores formed on the porous membrane surface side are connected to the pores inside the porous membrane (Ta-R1: R1 [N (C ₂ H ₅ ) ₂ ] _n ) is adsorbed on the surface of the porous film, thereby forming a state in which the opening surface at the connection position is blocked by the first molecule. . Then, as an example of a first reaction product film forming step, the NH ₃ supply step supplies NH _3, which is an example of a first reactive species that reacts with the first molecule, the said porous membrane surface A first TaN film that is one reaction product film is formed. A state in which the opening surface at the connection position is closed with the first molecule and the first TaN film as the first reaction product film is formed, thereby suppressing diffusion of Ta metal into the porous film. be able to. Further, as the second adsorption step, in the TaCl ₅ supply step, second molecules smaller than the opening size (Ta—R2: R2 is Cl _n ) are adsorbed on the surface of the first TaN film, as a reaction product film forming step, the NH ₃ supply process, the second NH _3, which is an example of a reactant supply, a second reaction product film on the first TaN film surface which reacts with the second molecule By forming the second TaN film, that is, increasing the thickness of the TaN film, the self-limiting effect can be enhanced and a highly purified TaN film can be formed. In other words, even when the second reaction product film is formed using a metal inorganic compound having a small molecular size and easily diffusing as a raw material, first, a metal organic compound having a large molecular size is supplied as a raw material, and the first molecule is By adsorbing to the surface of the porous membrane, a state in which the opening surface of the porous membrane is closed can be formed.

In the first embodiment, the first barrier metal film is formed using Ta [N (C ₂ H ₅ ) ₂ ] ₅ for 10 cycles at a film forming temperature of 300 ° C. However, the present invention is not limited to this. It is not a thing. The number of cycles may be any number of times as long as the opening surface of the hole connection portion on the surface of the p-lowk film is closed. Only one cycle may be formed to close the opening surface. Thereafter, the film may be formed to a desired film thickness by repeating a plurality of cycles using TaCl ₅ at a normal rate of, for example, 350 ° C.

FIG. 9 is a diagram showing the relationship between the film formation rate and the film formation temperature.
As shown in FIG. 9, in ALD film formation, film formation is possible at a predetermined temperature or higher, and the film formation rate is stabilized within a certain range (between B and C). Usually, from the viewpoint of ease of control and the like, it is desirable to set the film forming temperature in a range where the film forming rate is stable. In _{Ta [N (C 2 H 5} ) 2] 5, 250~300 ℃ is desirable. In TaCl _5, 300 to 350 ° C. is preferred. Moreover, since it will have a bad influence on a p-lowk film | membrane when it becomes 400 degreeC or more, it is unpreferable.

FIG. 10 is a diagram for explaining the molecular size of Ta [N (C ₂ H ₅ ) ₂ ] ₅ .
In ₅ molecules of Ta [N (C ₂ H ₅ ) ₂ ], _five pentadiethyl (N (C ₂ H ₅ ) ₂ ) groups are bonded to the Ta element. In this state, the molecular size is 1 nm or more. When the film formation temperature is increased, such N (C ₂ H ₅ ) ₂ groups are separated. Usually, at 250 to 300 ° C., it is considered that 2 to 3 N (C ₂ H ₅ ) ₂ groups are separated and bonded to the p-lowk film. In such a case, there is an effect of suppressing diffusion of Ta with respect to a hole connecting portion size (opening size) of 0.6 nm or less. Here, when the film formation temperature is lowered, the number of N (C ₂ H ₅ ) ₂ groups that are separated decreases. As the number of N (C ₂ H ₅ ) ₂ groups to be separated decreases, the molecular size also increases. 9, in other words, at a temperature lower than 250 ° C., as shown in the lower diagram of FIG. 10, for example, one N (C ₂ H ₅ ) _Two groups may separate and bind to the p-lowk membrane. In this case, the molecular size is 0.7 nm or more. Therefore, by bringing the temperature close to the limit temperature at which film formation is possible, the p-lowk film can be bonded with a molecular size larger than the molecular size at the normal film formation temperature. With Ta [N (C ₂ H ₅ ) ₂ ] ₅ , film formation is considered difficult at 150 ° C. or lower. Therefore, if bonded to the p-lowk film in the range of 150 to 250 ° C., it has a diffusion suppressing effect on a larger hole connecting part size (opening size), that is, a hole connecting part size of 0.7 nm or less. Can be mentioned.

  As described above, since the molecular size adsorbed on the p-lowk film can be controlled, it is possible to cope with a wide range according to the opening size of the p-lowk film.

In the first embodiment, Ta [N (C ₂ H ₅ ) ₂ ] ₅ is first used to block the hole connecting portion, and then TaCl ₅ is used to enhance the self-limiting effect and increase the purity of TaN. Although a film is formed, Ta [N (C ₂ H ₅ ) ₂ ] ₅ may be used to finally form a desired film thickness. For example, in the case of forming a TaN film on a p-lowk film having a hole connection portion size of 0.7 nm, the film is initially formed at a film formation temperature of 250 ° C. or lower (for example, 150 ° C.), and then at a normal rate, for example, The film may be formed up to a desired film thickness at 300 ° C.
Alternatively, as the first barrier metal film formation, only one cycle is formed at a film formation temperature of 250 ° C. or lower (for example, 150 ° C.), and then a normal rate of, for example, 300 ° C. is repeated a plurality of cycles to obtain a desired film thickness. It does not matter even if it forms into a film. Although the film formation rate is slow, film formation may be performed up to a desired film thickness at a film formation temperature of 250 ° C. or lower (eg, 150 ° C.) from the beginning.

In the case of multilayer wiring, the following steps are further performed.
FIG. 11 is a process cross-sectional view illustrating a part of the process of manufacturing the semiconductor device to be multilayered according to the first embodiment.
In FIG. 11, further, as an insulating film forming process, a SiC film forming process, a p-lowk film forming process, a He plasma processing process, a SiC film forming process, a p-lowk film forming process, a He plasma processing process, and a SiO ₂ film forming process. The process is shown. Subsequent steps will be described later.

In FIG. 11A, as a SiC film forming process which is a part of the insulating film forming process in the next layer, a SiC film 275 having a thickness of 50 nm is formed at a temperature of 400 ° C. in the same CVD apparatus subjected to reducing plasma. Form. The SiC film 275 functions as a diffusion preventing film, and by forming this SiC film 275, diffusion of Cu can be prevented. In addition to the SiC film 275 formed by the CVD method, a SiCN film, a SiCO film, a SiN film, or a SiO ₂ film can be used.

  11B, the p-lowk film forming process is a low dielectric constant film having a lower relative dielectric constant than the SiC film 275 on the SiC film 275, as in the process described with reference to FIG. 3B. Then, a p-lowk film 280 using a porous insulating material is formed. Similarly, as a He plasma treatment step, the surface of the p-lowk film 280 is modified by He plasma irradiation.

In FIG. 11C, after performing the He plasma treatment as a SiC film forming step, a SiC film 282 is formed on the p-lowk film 280 as a cap film by a CVD method. The SiC film 282 can be used as an etching stopper for forming grooves and holes for Cu filling by a dual damascene method to be described later by etching. Then, as a p-lowk film formation step, a p-lowk film 285 is formed on the SiC film 282. Similarly, as the He plasma processing step, the surface of the p-lowk film 285 is modified by He plasma irradiation in a CVD apparatus. Then, as the SiO ₂ film forming step, similar to the step described with reference to FIG. 2C, after performing the He plasma treatment, SiO ₂ 290 is formed on the p-lowk film 285 as a cap film by the CVD method. .

FIG. 12 is a process cross-sectional view illustrating a part of the process of manufacturing the semiconductor device to be multi-layered, following FIG.
In FIG. 12, an opening forming step for forming an opening, a barrier metal film forming step, a via for forming a via and an upper layer wiring, and a conductive material depositing step for depositing a conductive material to be an upper layer wiring forming step. , A seed film forming step. Subsequent steps will be described later.

In FIG. 12A, as the opening forming process, openings 152 and 154 which are wiring groove structures for producing dual damascene wiring in the lithography process and the dry etching process, as in the process described in FIG. Are formed on the SiO ₂ film 290, the p-lowk film 285, the SiC film 282, the p-lowk film 280, and the SiC film 275. As a hole forming step, an opening 152 serving as a via hole penetrating to the lower layer Cu film 260 deposited in the opening 150 is formed, and as an groove forming step, an opening 154 serving as a groove for an upper layer wiring is formed. Thereafter, the via bottom residue is removed with a dry etching cleaning liquid (for example, room temperature cleaning with EKC5920 for 5 minutes).

In FIG. 12B, as the barrier metal film forming step, a barrier metal material is formed on the surfaces of the openings 152 and 154 and the SiO ₂ film 290 formed by the opening forming step as in the step described with reference to FIG. A barrier metal film 242 using is formed to 5 nm by the ALD method. Others may be the same as described with reference to FIG.

  In FIG. 12C, as the seed film formation step, the cathode electrode in the subsequent electroplating step is performed by physical vapor deposition (PVD) method such as sputtering, as in the step described in FIG. A Cu thin film to be formed is deposited (formed) on the inner walls of the openings 152 and 154 in which the barrier metal film 242 is formed, the digging portion 156, and the surface of the substrate 200, using the seed film 252 as a seed film. Here, a seed Cu film was deposited to a thickness of 100 nm.

FIG. 13 is a process cross-sectional view illustrating a part of the process for manufacturing the semiconductor device to be multilayered, continued from FIG. 12.
FIG. 13 further shows a plating process and a planarization process.

  In FIG. 13A, as the plating process, as in the process described in FIG. 4C, the seed film 252 is used as a cathode electrode, and the Cu film 264 is formed in the openings 152 and 154 and the substrate by electrochemical growth such as electrolytic plating. 200 is deposited on the surface. As a result, a via 262 connected to the lower layer wiring and the upper layer wiring is formed in a part of the Cu film 264. Here, after a Cu film having a thickness of 300 nm is deposited, annealing is performed at a temperature of 250 ° C. for 30 minutes.

In FIG. 13B, as the planarization process, as in the process described with reference to FIG. 4D, the Cu film 264 serving as a wiring layer as a conductive portion deposited on the surface of the SiO ₂ film 290 by the CMP method, the seed By polishing and removing the film 252 and the barrier metal film 242, the film 252 and the barrier metal film 242 are planarized to form a buried structure as shown in FIG. The Cu film and the barrier metal film outside the groove are removed to form a second layer dual damascene Cu wiring.

Embodiment 2. FIG.
In the second embodiment, Ta [N (CH ₃ ) ₂ ] ₅ is used as a metal raw material, and a case where a TaN film as a barrier metal film is ALD formed on a p-MSQ as a porous low dielectric constant film is described. To do. Here, it is formed on a p-MSQ having a hole connecting portion size of 0.3 nm.
FIG. 14 is a flowchart showing a main part of the method of manufacturing a semiconductor device in the second embodiment.
In FIG. 14, _Ta in Figure _{1 [N (C 2 H 5} ) 2] 5 supplying step (S106) is, except that instead of the _{Ta [N (CH 3) 2} ] 5 feed step (S1406) includes a 1 It is the same.

As a barrier metal film forming step, a barrier metal film 240 using a barrier metal material is formed on the surface in the opening and the surface of the SiO ₂ film 222 by the ALD method.

Here, as in the first embodiment, a tantalum nitride (TaN) film is formed as the barrier metal film. First, as the metal material for forming the first barrier metal film, pentadimethyl tantalum (Ta [N (CH ₃ ) ₂ ] ₅ ) is used as the metal material, and the metal material is an example of a reactive species that reacts with the metal material. As a reducing gas, ammonia (NH ₃ ) is used, and as a purge gas, hydrogen (H ₂ ) is used. By using H ₂ as the purge gas, the following reactivity can be enhanced. Furthermore, since H ₂ can increase the purity, it is suitable for cleaning as described above.
FIG. 15 is a diagram showing a supply flow of each gas in the TaN film forming step.
As a Ta [N (CH ₃ ) ₂ ] ₅ supply step, Ta [N (CH ₃ ) ₂ ] ₅ is supplied for 1 s. Thereafter, as an H ₂ supply step, H ₂ is supplied for 1 s and purged. Then, the NH ₃ supply process, the NH ₃ 1s supplies. Then, as the H ₂ supply step, H ₂ is supplied for 1 s and purged. This process is defined as one cycle, and 10 cycles are supplied at a film forming temperature of 270 ° C.

By using Ta [N (CH ₃ ) ₂ ] ₅ which is a metal organic compound at a deposition temperature of 270 ° C., molecules adsorbed on the surface of the p-lowk film 220 exposed on the inner surface of the opening (see FIG. 2 Ta-R1) size can be 0.3 nm or more. As the ALD apparatus, an apparatus similar to that shown in FIG. 6 may be used.

Here, the gas amounts of Ta [N (CH ₃ ) ₂ ] ₅ , H ₂ , and NH ₃ are 1.68 Pa · m ³ / s (1000 sccm), and the pressure inside the chamber 600 is 339 Pa (3 Torr). . Here, the amount of gas, Ta for _{[N (CH 3) 2]} 5, 0.5Pa · m 3 /s(300sccm)~1.68Pa · m 3 / s (1000sccm) is desirable. For ^{_{NH 3, 1.68Pa · m 3 /s(1000sccm)~3.36Pa}} · m 3 / s (2000sccm) is desirable. For _{H 2} is ^{purge, 1.68Pa · m 3 /s(1000sccm)~3.36Pa · m} 3 / s (2000sccm) is desirable. The film forming pressure is desirably 665 Pa (5 Torr) or less. The film forming temperature is preferably 250 to 300 ° C.

As in the first embodiment, hydrazine (H ₂ NNH ₂ ) or a hydrazine compound such as 1-1 dimethyl hydrazine or 1-2 dimethyl hydrazine may be used as the reducing gas for the metal raw material.

Furthermore, as in the first embodiment, argon (Ar), nitrogen (N ₂ ), or He may be used as the purge gas.

Next, as in the first embodiment, tantalum chloride (TaCl ₅ ) is used as a metal raw material for forming the second barrier metal film in the TaN film forming step, and is an example of a reactive species that reacts with the metal raw material. Ammonia (NH ₃ ) is used as the reducing gas for the metal raw material, and hydrogen (H ₂ ) is used as the purge gas. By using TaCl ₅ as the metal raw material, the self-limiting performance can be improved. Further, by using TaCl ₅ , the TaN film can be highly purified.

In the second embodiment, as the first barrier metal film _{deposition, Ta [N (CH 3)} 2] has been 10 cycles formed in the deposition temperature of 270 ° C. using _5, this is not a limitation Absent. The number of cycles may be any number of times as long as the opening surface of the hole connection portion on the surface of the p-lowk film is closed. Only one cycle may be formed to close the opening surface. Thereafter, the film may be formed to a desired film thickness by repeating a plurality of cycles using TaCl ₅ at a normal rate of, for example, 350 ° C.

FIG. 16 is a diagram for explaining the molecular size of Ta [N (CH ₃ ) ₂ ] ₅ .
In _five molecules of Ta [N (CH ₃ ) ₂ ], _five pentadimethyl (N (CH ₃ ) ₂ ) groups are bonded to the Ta element. In this state, the molecular size is about 0.9 nm. Higher deposition temperatures according N _{(CH 3) 2} group is gradually separated. Usually, at 250 to 300 ° C., it is considered that _{2 to 3} N (CH ₃ ) ₂ groups are separated and bonded to the p-lowk film. As a result of an experiment formed on a p-MSQ having a hole connecting portion size of 0.3 nm, a relative dielectric constant k of 2.4, and a porosity of 30%, a hole connecting portion size (opening size) of 0.3 nm was obtained. On the other hand, it is known that there is an effect of suppressing diffusion of Ta. Therefore, there is an effect of suppressing the diffusion of Ta for the hole connecting portion size (opening size) of 0.3 nm or less. Here, when the film formation temperature is lowered, the number of N (CH ₃ ) ₂ groups that are separated decreases. As the number of N (CH ₃ ) ₂ groups to be separated decreases, the molecular size also increases. In the temperature at point A in FIG. 9, in other words, at a temperature lower than 250 ° C., as shown in the lower diagram of FIG. 16, the number of separations is lower than the normal film formation temperature, for example, one N (CH ₃ ) _2. Groups may separate and bind to the p-lowk membrane. In this case, the molecular size is 0.6 nm or more. Therefore, by bringing the temperature close to the limit temperature at which film formation is possible, the p-lowk film can be bonded with a molecular size larger than the molecular size at the normal film formation temperature. With Ta [N (CH ₃ ) ₂ ] ₅ , film formation is considered difficult at 200 ° C. or lower. Therefore, if bonded to the p-lowk film in the range of 200 to 250 ° C., Ta diffusion suppression is achieved for a larger hole connecting part size (opening size), that is, a hole connecting part size of 0.6 nm or less. An effect can be given.

  As described above, since the molecular size adsorbed on the p-lowk film can be controlled, it is possible to cope with a wide range according to the opening size of the p-lowk film.

In the second embodiment, first, Ta [N (CH ₃ ) ₂ ] ₅ is used to block the hole connecting portion, and then TaCl ₅ is used to enhance the self-limiting effect and to obtain a highly purified TaN film. Although formed, Ta [N (CH ₃ ) ₂ ] ₅ may be used to finally form a desired film thickness. For example, when a TaN film is formed on a p-lowk film having a hole connection portion size of 0.6 nm, the film is initially formed at a film formation temperature of 250 ° C. or lower (for example, 200 ° C.), and then at a normal rate, for example, The film may be formed up to a desired film thickness at 300 ° C.
Alternatively, as the first barrier metal film formation, a film is formed only for one cycle at a film formation temperature of 250 ° C. or less (eg, 200 ° C.), and then repeated at a normal rate of, eg, 270 ° C. for a plurality of cycles to obtain a desired film thickness. It does not matter even if it forms into a film. Although the film formation rate is slow, film formation may be performed up to a desired film thickness at a film formation temperature of 250 ° C. or lower (eg, 200 ° C.) from the beginning.

Embodiment 3 FIG.
In the third embodiment, a case will be described in which a TaN film is ALD formed as a barrier metal film on p-MSQ as a porous low dielectric constant film using TaCl ₅ as a metal raw material. Here, it is formed on a p-MSQ having a hole connecting portion size of 0.3 nm.
FIG. 17 is a flowchart showing a main part of the method of manufacturing a semiconductor device in the third embodiment.
17 is the same as FIG. 1 except that the Ta [N (C ₂ H ₅ ) ₂ ] ₅ supply step (S106) in FIG. 1 is replaced with the TaCl ₅ supply step (S1706).

As a barrier metal film forming step, a barrier metal film 240 using a barrier metal material is formed on the surface in the opening and the surface of the SiO ₂ film 222 by the ALD method.

Here, as in the first embodiment, a tantalum nitride (TaN) film is formed as the barrier metal film. First, tantalum chloride (TaCl ₅ ) is used as a metal material for forming the first barrier metal film, and ammonia (NH ₃ ) is used as a reducing gas for the metal material, which is an example of a reactive species that reacts with the metal material. ) And hydrogen (H ₂ ) is used as the purge gas. By using H ₂ as the purge gas, the following reactivity can be enhanced. Furthermore, since H ₂ can increase the purity, it is suitable for cleaning as described above.
FIG. 18 is a diagram showing a supply flow of each gas in the TaN film formation step.
As a TaCl ₅ supply step, TaCl ₅ is supplied for 3 seconds. Thereafter, as an H ₂ supply step, H ₂ is supplied for 1 s and purged. Then, the NH ₃ supply process, the NH ₃ 3s supplies. Then, as the H ₂ supply step, H ₂ is supplied for 1 s and purged. This process is defined as one cycle, and 10 cycles are supplied at a film forming temperature of 250 ° C.

By using TaCl ₅ which is a metal inorganic compound at a film forming temperature of 250 ° C., the size of molecules adsorbed on the surface of the p-lowk film 220 exposed on the inner surface of the opening (Ta-R1 in FIG. 2) is reduced. It can be 0.3 nm or more. As the ALD apparatus, an apparatus similar to that shown in FIG. 6 may be used.

Here, the gas amounts of Ta [N (CH ₃ ) ₂ ] ₅ , H ₂ , and NH ₃ are 1.68 Pa · m ³ / s (1000 sccm), and the pressure inside the chamber 600 is 339 Pa (3 Torr). . Here, the amount of gas, Ta for _{[N (CH 3) 2]} 5, 0.5Pa · m 3 /s(300sccm)~1.68Pa · m 3 / s (1000sccm) is desirable. For ^{_{NH 3, 1.68Pa · m 3 /s(1000sccm)~3.36Pa}} · m 3 / s (2000sccm) is desirable. For _{H 2} is ^{purge, 1.68Pa · m 3 /s(1000sccm)~3.36Pa · m} 3 / s (2000sccm) is desirable. The film forming pressure is desirably 665 Pa (5 Torr) or less. The film forming temperature is desirably 250 ° C. or higher and lower than 300 ° C.

As in the first embodiment, hydrazine (H ₂ NNH ₂ ) or a hydrazine compound such as 1-1 dimethyl hydrazine or 1-2 dimethyl hydrazine may be used as the reducing gas for the metal raw material.

Furthermore, as in the first embodiment, as a purge gas, argon (Ar) and nitrogen _{(N 2)} and may be used He.

Next, as in the first embodiment, tantalum chloride (TaCl ₅ ), which is the same kind of raw material, is used as the metal raw material for forming the second barrier metal film in the TaN film forming step, and the reactive species reacts with the metal raw material. it is an example of, as a reducing gas in the metal material, using ammonia (NH _3), as the purge gas, using hydrogen _{(H 2).} The film forming temperature is desirably 300 to 350 ° C. By using TaCl ₅ as the metal raw material, the self-limiting performance can be improved. Further, by using TaCl ₅ , the TaN film can be highly purified. As the ALD apparatus, an apparatus similar to that shown in FIG. 6 may be used. In the third embodiment, since the first and second barrier metal films are formed using the same kind of metal material at different film formation temperatures, as shown in FIG. 7, the first and second barrier metals are formed. In film formation, it is desirable that the chambers are processed separately for ease of temperature control.

As described above, using a low pressure CVD apparatus (here, an ALD apparatus), TaCl ₅ and NH ₃ are used on porous MSQ (hole connection portion size: 0.3 nm), and first, the film formation temperature is 250. At 10 ° C., TaCl ₅ (3 s) → H ₂ (1 s) → NH ₃ (3 s) → H ₂ (1 s) is set as one cycle, and 10 cycles of supply are performed. ₅ (1 s) → H ₂ (1 s) → NH ₃ (2 s) → H ₂ (1 s) After film formation as a cycle, TEM (transmission electron microscope) observation revealed that 2 nm of TaN was formed. No diffusion of the underlying p-MSQ was observed. By lowering the temperature of the initial film formation, decomposition can be suppressed and the surface molecular size can be made larger than the pore connecting portion size. As a result, diffusion into the p-MSQ can be suppressed.

In the third embodiment, the first barrier metal film is formed using TaCl ₅ for 10 cycles at a film formation temperature of 250 ° C., but is not limited thereto. The number of cycles may be any number of times as long as the opening surface of the hole connection portion on the surface of the p-lowk film is closed. Only one cycle may be formed to close the opening surface. Thereafter, as the second barrier metal film formation, a normal rate of, for example, 350 ° C. may be repeated a plurality of cycles, and a TaN film may be formed to a desired film thickness. When the first barrier metal film is formed by using TaCl ₅ for only one cycle at a film forming temperature of 250 ° C. to block the opening surface, it is desirable to supply TaCl ₅ for 10 s or longer. 10 to 15 s is also preferable from the viewpoint of throughput.

FIG. 19 is a diagram for explaining the molecular size of TaCl ₅ .
In the TaCl ₅ molecule, five halogen (Cl) groups are bonded to the Ta element. When the film forming temperature is increased, such Cl groups are separated. Usually, at 300 to 350 ° C., it is considered that _{2 to 3} N (CH ₃ ) ₂ groups are separated and bonded to the p-lowk film. As a result of the experiment, it was found that there was no effect of suppressing the diffusion of Ta with respect to the hole connecting portion size (opening size) of 0.3 nm. Here, when the film forming temperature is lowered, the number of Cl groups to be separated decreases. As the number of Cl groups to be separated decreases, the molecular size also increases. In the temperature at point A in FIG. 9, in other words, at a temperature lower than 300 ° C., as shown in the lower diagram of FIG. 18, the number of separations is smaller than that at the normal film formation temperature, for example, one N (CH ₃ ) _2. Groups may separate and bind to the p-lowk membrane. In this case, the molecular size is 0.3 nm or more. Therefore, by bringing the temperature close to the limit temperature at which film formation is possible, the p-lowk film can be bonded with a molecular size larger than the molecular size at the normal film formation temperature. With TaCl ₅ , film formation is considered difficult at 250 ° C. or lower. Therefore, when bonded to a p-lowk film in the range of 250 to 300 ° C., Ta diffusion suppression is achieved for a larger hole connecting part size (opening size), that is, a hole connecting part size of 0.3 nm or less. An effect can be given.

  As described above, since the molecular size adsorbed on the p-lowk film can be controlled, it is possible to cope with a wide range according to the opening size of the p-lowk film.

In the third embodiment, first, the hole connection portion is closed using TaCl ₅ at 250 ° C., and then the film formation rate is increased using TaCl ₅ at a normal film formation temperature (300 to 350 ° C.). Although the TaN film is formed, the film may be finally formed to a desired film thickness at a temperature lower than 300 ° C. (for example, 250 ° C.).

  As described above, in the first adsorption step, a raw material of the same type as the raw material used in the second adsorption step is supplied as the raw material for the first molecule, and is lower than the substrate temperature in the second adsorption step. It is also effective to adsorb the first molecule at the substrate temperature. Even when the same kind of raw material is used, first, the first molecule size is made larger than the second molecule size by adsorbing the first molecule at a substrate temperature lower than the substrate temperature in the second adsorption step. It can be adsorbed on the surface of the p-lowk film in a large state.

  If a raw material is selected according to the size of the opening, in combination with any of the above-described embodiments, it can be widely used in accordance with the properties of the porous film. In addition, the molecular size adsorbed on the porous film can be controlled by controlling the film forming temperature in accordance with the opening size. Since the molecular size adsorbed on the porous membrane can be controlled, it is possible to cope with a wide range according to the properties of the porous membrane.

Here, as a barrier metal formed by the ALD method, in addition to TaN, a nitride film of refractory metal such as tantalum carbonitride (TaCN), tungsten nitride (WN), tungsten carbonitride (WCN), titanium nitride (TiN), etc. Alternatively, a carbon nitride film, or tantalum (Ta), titanium (Ti), or tungsten (W) alone may be used. Alternatively, WSiN or the like may be used. Alternatively, a zirconium (Zr) -based barrier metal film may be used. Alternatively, a laminated film made of a plurality of these materials may be used. For example, as a metal raw material for a Ti-based barrier metal film, tetradiethyl titanium (Ti [N (C ₂ H ₅ ) ₂ ] ₄ ), tetradimethyl titanium (Ti [N (CH ₃ ) ₂ ] ₄ ), titanium chloride ( TiCl ₄ ) may be used. As a metal raw material for the W-based barrier metal film, it may be used WF _6.

  Here, as a material of the wiring layer in each of the above embodiments, a material mainly containing Cu used in the semiconductor industry, such as a Cu—Sn alloy, a Cu—Ti alloy, and a Cu—Al alloy, is used in addition to Cu. The same effect can be obtained.

  In the case of forming a multilayer wiring structure or the like, the substrate 200 in each drawing is formed by forming a lower wiring layer and an insulating film.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

  For example, the substrate 200 on which an interlayer insulating film is formed in each embodiment can have various semiconductor elements or structures not shown. Further, an interlayer insulating film may be further formed on a wiring structure having an interlayer insulating film and a wiring layer instead of the semiconductor substrate. The opening may be formed so that the semiconductor substrate is exposed, or may be formed on the wiring structure.

  Further, the film thickness of the interlayer insulating film and the size, shape, number, and the like of the opening can be appropriately selected from those required in the semiconductor integrated circuit and various semiconductor elements.

  In addition, any semiconductor device manufacturing method that includes the elements of the present invention and whose design can be changed as appropriate by those skilled in the art is included in the scope of the present invention.

  In addition, for the sake of simplicity of explanation, techniques usually used in the semiconductor industry, such as a photolithography process, cleaning before and after processing, are omitted, but it goes without saying that these techniques are included.

3 is a flowchart showing a main part of a method for manufacturing a semiconductor device in the first embodiment. It is a figure for demonstrating the mode of the molecule | numerator adsorb | sucked on a porous low dielectric constant film | membrane. FIG. 6 is a process cross-sectional view illustrating a process of the semiconductor device manufacturing method in the first embodiment. FIG. 6 is a process cross-sectional view illustrating a process of the semiconductor device manufacturing method in the first embodiment. It is a figure which shows the supply flow of each gas in a TaN film formation process. It is a figure which shows schematic structure of an ALD apparatus. It is a conceptual diagram for demonstrating the outline | summary of the apparatus provided with the several chamber. It is a figure which shows the other schematic structural example of an ALD apparatus. It is a figure which shows the relationship between a film-forming rate and film-forming temperature. _{Ta [N (C 2 H 5} ) 2] is a diagram for explaining the molecular size of _5. FIG. 6 is a process cross-sectional view illustrating a part of the process of manufacturing the semiconductor device to be multilayered according to the first embodiment. FIG. 12 is a process cross-sectional view illustrating a part of the process of manufacturing the semiconductor device having the multilayer wiring, continued from FIG. 11. FIG. 13 is a process cross-sectional view illustrating a part of the process of manufacturing the semiconductor device having the multilayer wiring, continued from FIG. 12. 10 is a flowchart showing a main part of a method for manufacturing a semiconductor device in a second embodiment. It is a figure which shows the supply flow of each gas in a TaN film formation process. _{Ta [N (CH 3) 2} ] is a diagram for explaining a ₅ molecular size. 10 is a flowchart showing a main part of a method for manufacturing a semiconductor device in a third embodiment. It is a figure which shows the supply flow of each gas in a TaN film formation process. It is a diagram for explaining the molecular size of TaCl _5. It is process sectional drawing which shows the manufacturing method of the semiconductor device which has the multilayer wiring structure which combined the conventional low-k film | membrane and Cu wiring. It is a gas supply flow figure which shows the example of film formation of the barrier metal by ALD method. It is a conceptual diagram for demonstrating a TaN film | membrane being formed in ALD method.

Explanation of symbols

10, 200 Base 20 TaR film 22 TaN film 150, 152, 154 Opening 156 Excavation part 212, 275, 282 SiC film 220, 280, 285 p-lowk film 221, 281 Insulating film 222, 290 SiO ₂ film 240, 242 Barrier metal film 250, 252 Seed film 260, 264 Cu film 262 Via 500 Device 510, 520, 530, 600 Chamber 540 Transfer chamber 550 Cassette chamber 610 Substrate holder 620 Shower head 630 Vacuum pump 650 Container

Claims (10)

A porous film forming step in which a plurality of pores are formed, and the pores formed on the surface side are connected to the internal pores to form a porous film that opens to the inside on the substrate;
A first adsorption step for adsorbing, on the porous membrane surface, first molecules larger than the opening size at a connection position where the pores formed on the porous membrane surface side are connected to the pores on the porous membrane inner side. When,
Supplying a first reactive species that reacts with the first molecule, and forming a first reaction product film on the porous film surface;
A second adsorption step for adsorbing a second molecule smaller than the opening size on the surface of the first reaction product film;
Supplying a second reactive species that reacts with the second molecule, and forming a second reaction product film on the surface of the first reaction product film;
A method for manufacturing a semiconductor device, comprising: In the first adsorption step, a metal organic compound is supplied as a raw material for the first molecule,
2. The method of manufacturing a semiconductor device according to claim 1, wherein in the second adsorption step, a metal inorganic compound is supplied as a raw material for the second molecule.   In the first adsorption step, a raw material of the same type as the raw material used in the second adsorption step is supplied as a raw material for the first molecule, and the first adsorption step is performed at a substrate temperature lower than the substrate temperature in the second adsorption step. 2. The method of manufacturing a semiconductor device according to claim 1, wherein one molecule is adsorbed.   2. The method of manufacturing a semiconductor device according to claim 1, wherein a low dielectric constant film having a relative dielectric constant of 2.5 or less is used as the porous film. For the porous film having an opening size of 0.6 nm or less, pentadimethyltantalum (Ta [N (CH ₃ ) ₂ ] ₅ ) is used as a raw material for the first molecule in the first adsorption step. 4. The method of manufacturing a semiconductor device according to claim 2, wherein In the first adsorption step, pentadiethyl tantalum (Ta [N (C ₂ H ₅ ) ₂ ] ₅ ) is used as the raw material for the first molecule for the porous film having an opening size of 0.7 nm or less. 4. The method of manufacturing a semiconductor device according to claim 2, wherein the method is used as a semiconductor device. Tantalum chloride (TaCl ₅ ) is used as a raw material for the first and second molecules in the first and second adsorption steps for the porous film having an opening size of 0.3 nm or less. A method for manufacturing a semiconductor device according to claim 3. A porous film forming step of forming a porous film on the substrate;
A pentadimethyl tantalum supply step of controlling the substrate temperature to a temperature lower than 250 ° C. and supplying pentadimethyl tantalum (Ta [N (CH ₃ ) ₂ ] ₅ ) onto the substrate on which the porous film is formed;
A reactive species supplying step of supplying reactive species that react with Ta [N (CH ₃ ) ₂ ] ₅ after supplying Ta [N (CH ₃ ) ₂ ] ₅ ;
A method for manufacturing a semiconductor device, comprising: A porous film forming step of forming a porous film on the substrate;
A pentadiethyl tantalum supply step of controlling the substrate temperature to a temperature lower than 250 ° C. and supplying pentadiethyl tantalum (Ta [N (C ₂ H ₅ ) ₂ ] ₅ ) onto the substrate on which the porous film is formed; ,
A reactive species supplying step of supplying reactive species that react with Ta [N (C ₂ H ₅ ) ₂ ] ₅ after supplying Ta [N (C ₂ H ₅ ) ₂ ] ₅ ;
A method for manufacturing a semiconductor device, comprising: A porous film forming step of forming a porous film on the substrate;
Controls substrate temperature to a temperature lower than 300 ° C., the porous film is formed on the substrate, a tantalum chloride supply step of supplying a tantalum chloride (TaCl _5),
TaCl ₅ after the supply to a reaction species supply step of supplying a reactive species that reacts with TaCl _5,
A method for manufacturing a semiconductor device, comprising:

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