JP2006173299A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a uniformly stable film by applying a surface treatment to a substrate with exposed many kinds of materials in the ALD method. <P>SOLUTION: Before feeding a metal-containing second reaction product into a reaction furnace in the atomic layer vapor phase growth method, a first hydroxide group-containing reaction product is fed at least once into the furnace. For example, the method has a first step of feeding the hydroxide group-containing first reaction product into the furnace, a second step of purging the furnace with an inert gas flow therein, a third step of feeding a second metal element-containing reaction product into the furnace, a fourth step of purging the furnace with the inert gas flow therein, a fifth step of feeding a third nitrogen-containing reaction product into the furnace, and a sixth step of purging the furnace with the inert gas flow therein. After one cycle of the first step to the sixth step, the cycle of the third step to the sixth step is repeated a plurality of times to form a thin film on the substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which pretreatment of a substrate surface is devised in an atomic layer vapor deposition method.

  In manufacturing a semiconductor device, it is often necessary to deposit a thin film with a uniform thickness on a portion such as a side wall of a wiring groove. This specific example will be described below.

That is, in recent years, the delay of signal propagation in the wiring of the semiconductor device has limited the element operation. The delay constant in wiring is represented by the product of wiring resistance and wiring capacitance. Therefore, in order to speed up the element operation by lowering the wiring resistance, a material having a relative dielectric constant smaller than that of conventional SiO ₂ is used for the wiring interlayer film and material, and Cu having a small specific resistance value is used for the wiring material. Is used. In forming the Cu wiring, deterioration of element characteristics due to diffusion of Cu into Si, deterioration of workability due to poor adhesion to the insulating film, and oxidation proceeds to the inside without forming a passive oxide film. It is necessary to solve problems such as deterioration of the wiring characteristics due to things. As one means for solving these problems, a barrier metal is provided at the interface between Cu and the wiring interlayer film. Specifically, it is required to deposit thin films of various materials such as W, Al, Cu, Ta, TaN, SiO ₂ , SiOC, SiN, HfOx, and HfAlO with good coverage.

  An atomic layer vapor deposition (hereinafter referred to as atomic layer deposition: “ALD”) method is known as a method suitable for such a purpose. ALD is performed by alternately supplying at least two kinds of raw materials to the substrate. At this time, the film forming conditions such as the substrate temperature, the raw material flow rate, and the raw material supply time are set to conditions under which these raw materials are saturated and adsorbed on the substrate. The film formation amount and composition are determined by the saturated adsorption amount, but in the ideal ALD, the saturated adsorption amount is constant on the wafer surface and the pattern, and uniform film formation on the wafer surface and the pattern is possible. Further, since only a saturated amount of molecules is adsorbed by a single supply, the film thickness can be controlled on the atomic order.

Taking advantage of this feature, a method of forming an oxide thin film by introducing water (H ₂ O) during a process of alternately supplying two kinds of raw materials to a substrate has also been proposed (for example, Patent Documents). 1).
JP 2003-209110 A

  However, since the ALD method uses the surface reaction of the substrate, the film formation speed and the film thickness depend on the surface state of the substrate. Therefore, for example, when a film is formed on a part where another type of film is exposed, such as the side wall of a wiring groove, the amount of adsorption, that is, the growth rate is different in each part of different materials, and stable film formation is not possible There was a problem.

FIG. 7 is a schematic cross-sectional view showing a state in which a film is formed on the side wall of the wiring trench in the conventional ALD method.
FIG. 7A shows a state in which the raw material is supplied to the sidewall of the wiring trench in the ALD method. As shown in the figure, a liner film 210 such as SiN, a low-k film 220, and a hard mask 230 such as SiO ₂ are formed in this order on a wiring layer 200 such as Cu. a liner film 210, the low-k film 220, the center of the hard mask 230 such as SiO _2, a trench 240 for embedding the wiring layer 200 such as Cu is provided. This figure is a cross-sectional view in which a TaN film is formed on the surface of a hard mask 230 such as SiO ₂ and on the bottom and side surfaces of the trench 240.

Here, PDMAT (Pentakis DiMethylAminoTantalum) 250, which is one of the raw materials for forming the TaN film, is contained in an Ar carrier gas and supplied to the reactor at 100 to 3000 sccm. At this time, as shown in the figure, PDMAT 250 is difficult to adsorb on the surface of the low-k film 220. This may be due to the fact that the CH ₃ group in the low-k film 220 inhibits the adsorption of the PDMAT 250 and that the PDMAT 250 is difficult to migrate on the surface of the low-k film 220.

  FIG. 7B is a schematic cross-sectional view showing a state in which a thin film is formed on the side wall of the wiring groove in the ALD method. As shown in the figure, a film 260 having a non-uniform film thickness is formed.

  The present invention has been made on the basis of recognition of such problems, and an object of the present invention is to provide a method for forming a uniform and stable film by performing surface treatment on a substrate on which various types of materials are exposed in the ALD method. It is to provide.

In order to achieve the above object, according to one aspect of the present invention,
A step of forming a thin film on a substrate by alternately supplying a second reactant containing a metal element and a third reactant into a reaction furnace;
A method of manufacturing a semiconductor device is provided, wherein a first reactant containing a hydroxyl group is supplied into the reaction furnace at least once before supplying the second reactant into the reaction furnace.

According to another aspect of the present invention,
A first step of supplying a first reactant containing a hydroxyl group into the reaction furnace;
A second step of purging by flowing an inert gas into the reactor;
A third step of supplying a second reactant containing a metal element into the reactor;
A fourth step of purging by flowing the inert gas into the reactor;
A fifth step of supplying a third reactant containing nitrogen into the reactor;
A sixth step of purging by flowing the inert gas into the reactor;
Have
The method includes a step of forming a thin film on a substrate by repeating the third step to the sixth step for a plurality of cycles after performing the first step to the sixth step for one cycle. A method for manufacturing a semiconductor device is provided.

According to yet another aspect of the present invention,
A first step of supplying a first reactant containing a hydroxyl group into the reaction furnace;
A second step of purging by flowing an inert gas into the reactor;
A third step of supplying a second reactant containing a metal element into the reactor;
A fourth step of purging by flowing the inert gas into the reactor;
A fifth step of supplying a third reactant containing nitrogen into the reactor;
A sixth step of purging by flowing the inert gas into the reactor;
Have
There is provided a method for manufacturing a semiconductor device, comprising a step of forming a thin film on a substrate by repeating the first to sixth steps a plurality of cycles.

According to yet another aspect of the present invention,
A first step of supplying a first reactant containing a hydroxyl group into the reaction furnace;
A second step of purging by flowing an inert gas into the reactor;
A third step of supplying a second reactant containing a metal element into the reactor;
A fourth step of purging by flowing the inert gas into the reactor;
A fifth step of supplying a third reactant containing nitrogen into the reactor;
A sixth step of purging by flowing the inert gas into the reactor;
Have
The method includes a step of forming a thin film on a substrate by repeating the first step to the sixth step for 5 cycles and then repeating the third step to the sixth step for a plurality of cycles. A method for manufacturing a semiconductor device is provided.

Here, the first reactant containing the hydroxyl group may be H ₂ O.
Alternatively, the first reactant containing the hydroxyl group may be an alcohol.

  According to the present invention, it is possible to provide a method for forming a uniform and stable film by performing surface treatment on a substrate on which many types of materials are exposed in the ALD method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a flowchart for explaining a method of manufacturing a semiconductor device according to an embodiment of the present invention. That is, FIG. 1 is a flowchart showing a method of forming a thin film using atomic layer vapor deposition (ALD).

First, the substrate to be treated is placed in a reaction furnace. Various types of substrates can be used as the substrate to be processed. Thereafter, the inside of the reaction furnace is purged. For purging the reactor, an inert gas such as Ar gas is used.
Next, as the first step 11, a first reactant containing a hydroxyl group (OH group) is supplied onto a substrate disposed in the reaction furnace. Examples of the first reactant containing a hydroxyl group (OH group) include alcohols such as H ₂ O, methanol (CH ₃ OH), and ethanol (C ₂ H ₅ OH). For example, the first reactant is contained in an inert gas such as an Ar carrier gas and supplied to the reaction furnace at 100 to 1000 sccm. The gas flow rate can be appropriately changed depending on the substrate to be processed and the type of gas.

Next, as the second step 12, the inside of the reaction furnace is purged. An inert gas such as Ar gas is introduced into the reaction furnace to remove unreacted substances.
Next, as the third step 13, a second reactant containing a metal element is supplied. As a second reactant containing a metal element, for example, when a TaN film is formed, PDMAT (Pentakis DiMethylAminoTantalum) can be cited. However, the present invention is not limited to PDMAT, and can be appropriately changed according to various films such as W, Al, Cu, Ta, TaN, SiO ₂ , SiOC, SiN, HfOx, and HfAlO. The second reactant is contained in, for example, an inert gas such as an Ar carrier gas and supplied to the reaction furnace at 100 to 3000 sccm.

Next, as the fourth step 14, the inside of the reaction furnace is purged. That is, an inert gas such as Ar gas is introduced into the reaction furnace to remove unreacted substances.
Next, as a fifth step 15, a third reactant containing nitrogen is supplied. Examples of the third reactant containing nitrogen include NH ₃ . The third reactant is contained in, for example, an inert gas such as an Ar carrier gas and supplied to the reaction furnace at 100 to 5000 sccm.
Finally, as the sixth step 16, the inside of the reaction furnace is purged. That is, an inert gas such as Ar gas is introduced into the reaction furnace to remove unreacted substances.

After performing the first to sixth steps for one cycle, the third to sixth steps are set to one cycle, and this cycle is repeated until the formed thin film reaches a desired thickness.
Next, the effect of supplying the first reactant containing a hydroxyl group (OH group) in the first step 11 described above will be described.

FIG. 2 is a process cross-sectional view illustrating the main part of the method of manufacturing a semiconductor device according to the embodiment of the present invention. In the figure, as an example, a process sectional view in the case where a TaN film is formed on an interlayer insulating film (low-k film) made of a low dielectric constant material is illustrated. In particular, the case of forming on a low-k film made of a low dielectric constant material containing a CH ₃ group is illustrated.

FIG. 2A is a schematic view illustrating the cross-sectional structure of the opening of the trench 24 in the first step 11 described above. As shown in the figure, a liner film 21 such as SiN, a low-k film 22 and a hard mask 23 such as SiO ₂ are laminated in this order on a wiring layer 20 such as Cu, and wiring such as Cu is formed. In order to embed layer 20, trenches 24 are provided therethrough. Then, a TaN film is formed on the surface of the hard mask 23 and the bottom and side surfaces of the trench 24.

In the first step 11, since the first reactant containing the hydroxyl group (OH group) is supplied, the OH group is adsorbed on the surface of the trench 24. That is, OH groups are adsorbed on the surfaces of the wiring layer 20 such as Cu, the liner film 21 such as SiN, the low-k film 22, and the hard mask 23 such as SiO ₂ .

  FIG. 2B is a schematic view illustrating the cross-sectional structure of the opening of the trench 24 in the third step 13 described above. As shown in the figure, in the third step 13 described above, a second reactant 25 containing a metal element is supplied. For example, as the second reactant 25 containing a metal element, PDMAT (PentakisDiMethylAminoTantalum) can be contained in an Ar carrier gas and supplied to the reactor at 100 to 3000 sccm.

Here, since the surface of the opening of the trench 24 is terminated with an OH group, PDMAT can be migrated over a long distance. As a result, PDMAT is easily adsorbed on the surface of the low-k film 22 similarly to the surface of the liner film 21 such as SiN and the hard mask 23 such as SiO _2, so that a thin film having a uniform thickness can be formed. In addition, the step coverage of the thin film is also improved.

  FIG. 2C is a schematic view illustrating the cross-sectional structure of the opening of the trench 24 after repeating the first to sixth steps described above for 5 to 6 cycles. As shown in the figure, according to the method for manufacturing a semiconductor device according to the embodiment of the present invention, a thin film 26 having a uniform film thickness and good coverage can be formed.

  Next, another effect of supplying the first reactant containing a hydroxyl group (OH group) in the first step 11 described above will be described.

FIG. 3 is a process cross-sectional view illustrating the main part of the method of manufacturing a semiconductor device according to the embodiment of the present invention. In the figure, as an example, a process sectional view in the case where a TaN film is formed on an interlayer insulating film (low-k film) made of a low dielectric constant material is illustrated. In particular, the case of forming on a low-k film made of a low dielectric constant material containing a CH ₃ group is illustrated.

FIG. 3A is a schematic view illustrating the cross-sectional structure of the low-k film 31 immediately after the low-k film 31 is entered. The low-k film 31 is made of a low dielectric constant material containing a CH ₃ group.

FIG. 3B is a schematic view illustrating the cross-sectional structure of the low-k film 31 in the first step 11 described above. That is, it represents a state in which H ₂ O is supplied into the reaction furnace. When H ₂ O is supplied as shown in the figure, the OH group of H ₂ O desorbs the CH ₃ group in the low-k film 31, and the OH group is adsorbed on the surface of the low-k film 31. The CH ₃ group in the low-k film 31 tends to inhibit PDMAT and the like from adsorbing to the surface of the low-k film 31. Accordingly, if H ₂ O is supplied before PDMAT or the like is supplied as in this embodiment, the PDMAT supplied thereafter is easily adsorbed on the surface of the low-k film 31.

FIG. 4 is a schematic view illustrating the main configuration of an ALD apparatus that can be used in this embodiment.
The ALD apparatus shown in FIG. 4 will be described. The apparatus has a chamber 41 in which a substrate stage 46 is accommodated. On the substrate stage 46, the substrate 35 of the semiconductor device being manufactured is placed. The chamber 41 is provided with gas inlets 42 to 44, and a predetermined gas is introduced therein. The chamber 41 is provided with a gas discharge port 47 for discharging the introduced gas and allowing the inside of the chamber 41 to be exhausted by an exhaust means such as a vacuum pump (not shown).

  During deposition by ALD, source gas, carrier gas, purge gas, and the like are appropriately introduced from the gas inlets 42 to 44, respectively, and by decomposition using thermal decomposition, plasma, or the like on or near the surface of the substrate 45 to be processed. A predetermined deposition species is formed, and a thin film is formed on the substrate 45 to be processed.

As described with reference to FIGS. 1 to 4, before the step of supplying the second reactant containing the metal element, the first reactant containing the hydroxyl group (OH group) is supplied to the surface of the substrate to be processed. Adsorb OH groups. By doing so, it is possible to promote the migration of the second reactant containing the metal element, which is supplied thereafter, on the surface of the substrate to be processed and the adsorption to the surface of the substrate to be processed. In particular, when the substrate to be processed is formed from another type of material, or when the substrate to be processed is made of a material containing a CH ₃ group, a greater effect can be obtained.

  As a result, in the ALD method, a uniform film with good coverage can be formed at a high film formation rate. In particular, it becomes possible to form a TaN film by the ALD method in the Cu wiring groove where various materials are exposed.

Next, a first embodiment of the present invention will be described.
FIG. 5 is a flowchart showing a method for manufacturing a semiconductor device according to the first embodiment of the present invention.
As shown in the figure, in the production method in the present example, the sixth step of purging after the supply of the third reactant containing nitrogen from the first step 11 of supplying the first reactant containing the hydroxyl group (OH group) is performed. The cycle up to step 16 is set as one cycle, and this cycle is repeated until a desired film thickness is reached.

  In the embodiment described above, the first step 11 for supplying the first reactant containing a hydroxyl group (OH group) was performed only once. However, in the atomic layer vapor deposition method, it can be formed further by repeating the raw material supply for several cycles. Therefore, immediately after the first step 11 for supplying the first reactant containing the hydroxyl group (OH group) is performed once, the surface of the low-k film to which the hydroxyl group (OH group) is not adsorbed is exposed. Yes. Therefore, in this example, one cycle is from the first step 11 for supplying the first reactant containing a hydroxyl group (OH group) to the sixth step 16 for purging after the third reactant containing nitrogen is supplied. The first reactant containing a hydroxyl group (OH group) is supplied each time before supplying the second reactant containing metal.

  Thus, according to the present Example, the effect by supplying the 1st reactant containing a hydroxyl group (OH group) can be acquired after the 2nd cycle.

Next, a second embodiment of the present invention will be described.
FIG. 6 is a flowchart showing a method of manufacturing a semiconductor device according to the second embodiment of the present invention.
As shown in the figure, in the production method in the present example, the sixth reactant purged after the supply of the third reactant containing nitrogen from the first step 11 of supplying the first reactant containing the hydroxyl group (OH group). The process up to step 16 is defined as one cycle, and this is repeated for five cycles. Thereafter, the cycle from the step 13 for supplying the second reactant containing the metal element to the sixth step 16 for purging after the supply of the third reactant containing nitrogen is repeated until a desired film thickness is reached.

When the first to sixth steps are repeated for about 5 cycles, a thin film is formed. That is, up to 5 cycles, there is a possibility that a region where PDMAT is not adsorbed is exposed on the surface of the low-k film. Therefore, the hydroxyl group is used to promote the adsorption of the second reactant containing the metal element. The supply of the first reactant containing (OH group) is repeated.
After the TaN film is formed after 5 cycles, the step of supplying the first reactant containing a hydroxyl group (OH group) is omitted, and the step of supplying PDMAT and NH ₃ is repeated.

As described above, according to the present embodiment, the effect of supplying H ₂ O is continued until one TaN film is formed, and an extra step is omitted after one TaN film is formed. By doing so, the same effect as that obtained in the above-described embodiment can be further doubled and efficiently obtained.

The embodiments of the present invention have been described above with reference to specific examples.
However, the present invention is not limited to these specific examples. For example, specific structures, materials, types of supply raw materials, and the like of the semiconductor device according to the present invention are appropriately selected from those known by those skilled in the art within the scope of the present invention.

6 is a flowchart for explaining a method of manufacturing a semiconductor device according to an embodiment of the present invention. It is process sectional drawing showing the principal part of the manufacturing method of the semiconductor device concerning embodiment of this invention. It is process sectional drawing showing the principal part of the manufacturing method of the semiconductor device concerning embodiment of this invention. It is a schematic diagram which illustrates the principal part structure of the ALD apparatus which can be used in embodiment of this invention. It is a flowchart showing the manufacturing method of the semiconductor device concerning the 1st example of the present invention. It is a flowchart showing the manufacturing method of the semiconductor device concerning the 2nd Example of this invention. It is process sectional drawing showing the principal part of the manufacturing method of the conventional semiconductor device.

Explanation of symbols

11 First Step 12 Second Step 13 Third Step 14 Fourth Step 15 Fifth Step 16 Sixth Step 20 Wiring Layer 21 Liner Film 22, 31 Low-k Film 23 Hard Mask 24 Trench 25 Second Bireactant 200 Wiring layer 210 Liner film 220 Low-k film 230 Hard mask 240 Trench

Claims (6)

A step of forming a thin film on a substrate by alternately supplying a second reactant containing a metal element and a third reactant into a reaction furnace;
A method of manufacturing a semiconductor device, comprising: supplying a first reactant containing a hydroxyl group into the reaction furnace at least once before supplying the second reactant into the reaction furnace. A first step of supplying a first reactant containing a hydroxyl group into the reaction furnace;
A second step of purging by flowing an inert gas into the reactor;
A third step of supplying a second reactant containing a metal element into the reactor;
A fourth step of purging by flowing the inert gas into the reactor;
A fifth step of supplying a third reactant containing nitrogen into the reactor;
A sixth step of purging by flowing the inert gas into the reactor;
Have
The method includes a step of forming a thin film on a substrate by repeating the third step to the sixth step for a plurality of cycles after performing the first step to the sixth step for one cycle. A method for manufacturing a semiconductor device. A first step of supplying a first reactant containing a hydroxyl group into the reaction furnace;
A second step of purging by flowing an inert gas into the reactor;
A third step of supplying a second reactant containing a metal element into the reactor;
A fourth step of purging by flowing the inert gas into the reactor;
A fifth step of supplying a third reactant containing nitrogen into the reactor;
A sixth step of purging by flowing the inert gas into the reactor;
Have
A method of manufacturing a semiconductor device, comprising: forming a thin film on a substrate by repeating the first to sixth steps a plurality of cycles. A first step of supplying a first reactant containing a hydroxyl group into the reaction furnace;
A second step of purging by flowing an inert gas into the reactor;
A third step of supplying a second reactant containing a metal element into the reactor;
A fourth step of purging by flowing the inert gas into the reactor;
A fifth step of supplying a third reactant containing nitrogen into the reactor;
A sixth step of purging by flowing the inert gas into the reactor;
Have
The method includes a step of forming a thin film on a substrate by repeating the first step to the sixth step for 5 cycles and then repeating the third step to the sixth step for a plurality of cycles. A method for manufacturing a semiconductor device. The method for manufacturing a semiconductor device according to claim 1, wherein the first reactant containing a hydroxyl group is H ₂ O.   The method for manufacturing a semiconductor device according to claim 1, wherein the first reactant containing a hydroxyl group is an alcohol.

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