JP7668093B2 - Film forming method, film forming apparatus, and method for manufacturing semiconductor device - Google Patents

Description

This disclosure relates to a film formation method, a film formation apparatus, and a method for manufacturing a semiconductor device.

In the manufacturing process of semiconductor devices, metal films such as TiN films are used for various purposes, such as electrodes such as the lower electrode of DRAM, barrier films, etc. General thin film formation techniques are used to form metal films such as TiN films, and Patent Document 1 describes forming a TiN film by atomic layer deposition (ALD).

JP 2015-78418 A

The present disclosure provides a film formation method, a film formation apparatus, and a method for manufacturing a semiconductor device that can suppress oxidation of the film surface when forming a metal film.

A film forming method according to one aspect of the present disclosure includes the steps of: providing a substrate in a processing vessel; forming a metal-based film on the substrate in the processing vessel; and thereafter, supplying a Si-containing gas into the processing vessel with the substrate provided in the processing vessel, causing the Si-containing gas to be adsorbed by the metal-based film, and forming a surface layer on a surface of the metal-based film, the surface layer containing Si and suppressing oxidation of the metal-based film when the substrate on which the metal-based film has been formed is transported out of the processing vessel .
(However, this does not include the case where the metal film is a Ti film or a TiN film and the surface layer is a TiSiN film) .

The present disclosure provides a film formation method, a film formation apparatus, and a semiconductor manufacturing method that can suppress oxidation of the film surface when forming a metal-based film.

1 is a flowchart illustrating a film forming method according to an embodiment. 1A to 1C are cross-sectional views illustrating process steps of a film forming method according to an embodiment. 1 is a cross-sectional view showing an example of a film forming apparatus when a film forming method according to an embodiment is applied to the formation of a TiN film. 4 is a cross-sectional view showing an example of the structure of a semiconductor wafer on which a film formation process is performed by the apparatus of FIG. 3. 5 is a cross-sectional view showing a state in which a TiN film is formed on the semiconductor wafer of FIG. 4. FIG. 11 is a cross-sectional view showing a state in which a surface layer is formed on the surface of the TiN film by performing a step of supplying DCS gas, which is a Si-containing gas, into the chamber after the TiN film is formed. 1 is a timing chart showing a specific gas supply sequence of a TiN film forming process and a Si-containing gas supply process, in which SiH ₄ gas is supplied once (one cycle) as the Si-containing gas. 1 is a timing chart showing a specific gas supply sequence of a TiN film forming process and a Si-containing gas supply process, in which SiH ₄ gas is supplied multiple times (multiple cycles) as the Si-containing gas. 1 shows a specific gas supply sequence for the TiN film forming process and the Si-containing gas supply process, in which SiH ₄ gas and NH ₃ gas are supplied alternately multiple times. FIG. 13 is a graph showing the relationship between the DCS gas flow rate and the specific resistance of a TiN film. FIG. 13 is a graph showing the relationship between DCS gas supply time and the specific resistance of a TiN film. FIG. 13 _is a diagram showing the results of measuring the sheet resistance and uniformity of the TiN film in the case where one cycle of _SiH4 gas supply is performed as a Si-containing gas supply process, five cycles of _SiH4 gas supply with purging in between, and a case where no SiH4 gas supply is performed after the TiN film is formed. FIG. 13 is a diagram showing the _results of measuring the _sheet resistance and uniformity of the TiN film in the case where one cycle of supplying _SiH4 gas and supplying _NH3 gas was performed as a Si-containing gas supply process, five cycles of supplying SiH4 gas and supplying _NH3 gas, and a case where no supply of SiH4 gas was performed after forming the TiN film. 10 is a cross-sectional view showing a state in which a surface layer is formed on the surface of a TiN film and then a SiGe film is formed. FIG.

The following describes the embodiment with reference to the attached drawings.

<One embodiment of the film forming method>
First, one embodiment of a film forming method will be described.
Fig. 1 is a flow chart showing a film forming method according to an embodiment, and Fig. 2 is a cross-sectional view of the process. As shown in Fig. 1 and Fig. 2, the film forming method according to the embodiment includes a step of providing a substrate 201 in a processing vessel of a film forming apparatus (step 1, Fig. 2(a)), a step of providing a metal-based film 202 on the substrate 201 in the processing vessel (step 2, Fig. 2(b)), and then a step of supplying a Si-containing gas into the processing vessel with the substrate 201 provided in the processing vessel (step 3, Fig. 2(c)).

In step 1, a substrate 201 for forming a metal-based film is placed in a processing vessel of a film forming apparatus in preparation for film formation. The substrate 201 is not particularly limited, but an example is a semiconductor substrate (semiconductor wafer) having a semiconductor base such as silicon. In this case, the substrate 201 may be the semiconductor base itself, or may be a semiconductor base on which one or more films having desired functions are formed.

In step 2, the metal-based film 202 formed on the substrate 201 may be a metal film or a metal compound film whose characteristics may be deteriorated by oxidation. Specific examples include a Ti film, a TiN film, a Ta film, a TaN film, a W film, an Al film, a Mo film, a Ru film, a Co film, and a Ni film.

The deposition method for the metal film 202 is not particularly limited, and examples include thin film formation techniques such as the ALD method, the CVD method, and the PVD method. From the viewpoint of obtaining good step coverage, the ALD method is preferred.

Step 3 is a post-deposition process in which a Si-containing gas is supplied into the processing vessel after the metal film 202 is formed. By supplying the Si-containing gas, the Si-containing gas is adsorbed onto the surface of the metal film, forming a surface layer 203 containing Si.

Other gases, such as ammonia (NH ₃ ), which is a reactive gas that reacts with the Si-containing gas, or an inert gas may be supplied together with the Si-containing gas. The Si-containing gas is not particularly limited, but examples thereof include silane-based compounds, chlorosilane-based compounds, and organic silane-based compounds. Examples of silane-based compounds include silane (monosilane) and disilane. Examples of chlorosilane-based compounds include dichlorosilane, monochlorosilane, trichlorosilane, silicon tetrachloride, and hexachlorodisilane. Examples of organic silane-based compounds include aminosilane-based compounds such as butylaminosilane, bis(tert-butylaminosilane, and dimethylaminosilane. Among these, at least one of dichlorosilane, silane, and disilane, which are generally used in semiconductor manufacturing processes, can be suitably used.

When only a Si-containing gas or a Si-containing gas and an inert gas are supplied, the Si-containing gas is thermally decomposed to form a Si layer as the surface layer 203. The surface layer 203 may have a reaction layer in which Si reacts with the base. When a reaction gas is supplied in addition to the Si-containing gas, a Si compound layer may be formed as the surface layer 203 by the reaction between the Si-containing gas and the reaction gas. For example, when a nitrogen-containing gas such as NH ₃ gas is used as the reaction gas, a SiN layer may be formed as the surface layer 203.

The temperature and pressure conditions for the process of supplying the Si-containing gas in step 3 vary slightly depending on the Si-containing gas used, but the temperature is preferably in the range of 400 to 700°C, and the pressure is preferably in the range of 266.6 to 13,332.2 Pa (2 to 100 Torr).

The supply of the Si-containing gas may be performed once or multiple times. When the Si-containing gas is supplied once, the amount of adsorption can be controlled by the supply time, and in this case, the supply time of the Si-containing gas is preferably 0.05 to 20 seconds. Furthermore, by repeating the supply of the Si-containing gas multiple times, the amount of adsorption of the Si-containing gas can be controlled by the number of times, and the controllability of the layer thickness of the surface layer 203 can be improved. In this case, the supply time of one Si-containing gas supply is preferably 0.05 to 4 seconds, and the number of times (number of cycles) of the Si-containing gas supply is preferably in the range of 1 to 5 times. Furthermore, it is preferable to perform purging with an inert gas between the supplies of the Si-containing gas.

In addition, when a reactive gas is supplied in addition to the Si-containing gas, the reactive gas may be supplied after the Si-containing gas is supplied, or the Si-containing gas and the reactive gas may be alternately supplied multiple times. By alternately supplying multiple times, a Si compound layer can be formed as the surface layer 203 with good layer thickness controllability. The Si-containing gas and the reactive gas may be supplied simultaneously. For example, a SiN layer can be formed as the surface layer 203 by using NH ₃ gas as the reactive gas.

When supplying a Si-containing gas to form the surface layer 203, the amount of adsorption of the Si-containing gas is not particularly limited, and an oxidation suppression effect can be obtained with one molecular layer or more. If the amount of adsorption of the Si-containing gas becomes too large, there is a concern that it may affect the characteristics, so the amount of adsorption is preferably 15 nm or less when converted into a film thickness, and the thickness of the surface layer 203 is preferably in the range of 0.5 to 1 nm. Similarly, when supplying a Si-containing gas and a reactive gas to form a Si compound layer such as a SiN layer as the surface layer 203, the thickness of the surface layer 203 is preferably in the range of 0.5 to 1 nm.

The reason for carrying out the process of supplying a Si-containing gas after forming the metal film is explained below.

After the metal film has been formed, the substrate is removed from the processing vessel and used for the next process. If the substrate is removed into the atmosphere before the next process, the formed metal film is exposed to oxygen and moisture in the air, and is oxidized from the surface to the bulk direction, causing deterioration of the characteristics. For example, the resistance of the film increases. In particular, when the film is thin, the effect of oxidation from the surface becomes greater, and deterioration of the characteristics becomes more noticeable.

After forming the metal film 202 on the substrate 201 in the processing vessel, a Si-containing gas is supplied into the processing vessel, so that the Si-containing gas is adsorbed onto the surface of the metal film 202, forming a surface layer 203 containing Si. As a result, the substrate is unloaded without the surface of the metal film 202 being exposed, thereby suppressing oxidation of the metal film 202.

The next process may be carried out in another processing vessel in the vacuum system, but even in that case, some oxidation of the metal film occurs due to oxygen and moisture in the vacuum transfer system, so the oxidation suppression effect of the process of supplying a Si-containing gas is effective.

The surface layer 203 is formed by heating the Si-containing gas adsorbed on the surface of the metal film 202, and may have a reaction layer formed by reaction between the adsorbed Si-containing gas and the surface of the metal film.

As mentioned above, the effect of oxidation of a metal film is greater the thinner the film is, and deterioration of characteristics such as increased resistance becomes more noticeable. Therefore, when the thickness of the metal film is 5 nm or less, the effect of suppressing oxidation by the Si-containing gas is greater.

After the step of supplying the Si-containing gas, the substrate is removed from the processing vessel, and the next film formation step is carried out by another film formation device. At this time, since a surface layer containing Si is formed on the surface of the metal-based film on the substrate, if the next film formation step is a step of forming a Si-containing film, the affinity will be high. At this time, since Si is present on the surface on which the Si-containing film is to be formed, this can have a favorable effect of shortening the incubation time when forming the Si-containing film.

<Application to TiN film formation>
Next, the formation of a TiN film will be described as a specific application example.
The TiN film as a metal-based film is used as a barrier film or an electrode, and is required to have low electrical resistance. The ALD method, which can obtain a film with high step coverage and good film quality, is often used to form the TiN film. After the TiN film is formed, the next film formation process, for example, the formation of a SiGe film, is performed. In this case, since the two films are formed in different devices, the TiN film is transferred to the atmosphere after it is formed. At this time, the TiN film is oxidized by moisture and oxygen in the atmosphere, and the resistance increases, which causes a problem that it is difficult to obtain good device characteristics. For this reason, a process of supplying a Si-containing gas is performed to form a surface layer on the surface of the TiN film, thereby suppressing the oxidation of the TiN film after the substrate is transferred from the processing vessel.
The specific details will be explained below.

[TiN film forming device]
FIG. 3 is a cross-sectional view showing an example of a film forming apparatus when the film forming method of the embodiment is applied to the formation of a TiN film.

The film forming apparatus 100 has a chamber 1 which is a processing vessel, a susceptor (substrate mounting table) 2, a shower head 3, an exhaust unit 4, a gas supply mechanism 5, and a control unit 6.

The chamber 1 is made of a metal such as aluminum and has a generally cylindrical shape. A transfer port 26 is formed on the side wall of the chamber 1 for transferring a semiconductor wafer (hereinafter, simply referred to as a wafer) W, which is a substrate, to a vacuum transfer chamber (not shown) by a transfer mechanism (not shown), and the transfer port 26 can be opened and closed by a gate valve 27. An annular exhaust duct 28 with a rectangular cross section is provided on the main body of the chamber 1. A slit 28a is formed along the inner peripheral surface of the exhaust duct 28. An exhaust port 28b is formed on the outer wall of the exhaust duct 28. A ceiling wall 29 is provided on the upper surface of the exhaust duct 28 so as to close the upper opening of the chamber 1. The space between the ceiling wall 29 and the exhaust duct 28 is airtightly sealed by a seal ring 30.

The susceptor 2 is used to place a substrate, i.e., a wafer W, inside the chamber 1. It is disk-shaped and sized to fit the wafer W, and is installed horizontally. The susceptor 2 is supported by a support member 33. A heater 31 for heating the wafer W is embedded inside the susceptor 2. The heater 31 is powered by a heater power source (not shown) and generates heat. The output of the heater 31 is controlled to control the wafer W to a predetermined temperature. The susceptor 2 is provided with a ceramic cover member 32 that covers the outer peripheral area of the wafer placement surface and the sides.

The support member 33 that supports the susceptor 2 extends from the center of the bottom surface of the susceptor 2 through a hole formed in the bottom wall of the chamber 1 below the chamber 1, and its lower end is connected to a lifting mechanism 34, which allows the susceptor 2 to be raised and lowered via the support member 33 between the processing position shown in FIG. 3 and a transfer position shown by a dashed line below that position where a wafer can be transferred. In addition, a flange 35 is attached to the support member 33 below the chamber 1, and a bellows 36 is provided between the bottom surface of the chamber 1 and the flange 35 to separate the atmosphere inside the chamber 1 from the outside air and to expand and contract as the susceptor 2 is raised and lowered.

Three wafer support pins 37 (only two shown) are provided near the bottom surface of the chamber 1, protruding upward from a lift plate 37a. The wafer support pins 37 can be raised and lowered via the lift plate 37a by a lift mechanism 38 provided below the chamber 1, and can be inserted into through holes 22 provided in the susceptor 2 at the transfer position, allowing them to protrude and retract relative to the top surface of the susceptor 2. This allows the wafer W to be transferred between the wafer transfer mechanism (not shown) and the susceptor 2.

The showerhead 3 is used to supply processing gas into the chamber 1 in a shower-like manner, and is provided at the top of the chamber 1 facing the susceptor 2, with approximately the same diameter as the susceptor 2. The showerhead 3 has a main body 39 fixed to the ceiling wall 29 of the chamber 1, and a shower plate 40 connected below the main body 39. A gas diffusion space 41 is formed between the main body 39 and the shower plate 40.

A plurality of gas dispersion members 42 are provided in the gas diffusion space 41. A plurality of gas discharge holes are formed around the periphery of the gas dispersion members 42. The gas dispersion members 42 are connected to one end of each of a plurality of gas supply paths 43 provided in the main body portion 39. The other end of the gas supply path 43 is connected to a diffusion portion 44 formed in the center of the upper surface of the main body portion 39. In addition, three gas introduction holes 45a, 45b, and 45c are provided in the center of the main body portion 39, which penetrate from the upper surface to the diffusion portion 44.

A downwardly protruding annular protrusion 40b is formed on the periphery of the shower plate 40, and gas ejection holes 40a are formed on the inner flat surface of the annular protrusion 40b of the shower plate 40. When the susceptor 2 is in the processing position, a processing space S is formed between the shower plate 40 and the susceptor 22, and the annular protrusion 40b and the upper surface of the cover member 32 of the susceptor 2 are close to each other to form an annular gap 48.

The exhaust unit 4 is equipped with an exhaust pipe 46 connected to the exhaust port 28b of the exhaust duct 28, and an exhaust mechanism 47 having a vacuum pump, a pressure control valve, etc., connected to the exhaust pipe 46. During processing, gas in the chamber 1 reaches the exhaust duct 28 through the slit 28a, and is exhausted from the exhaust duct 28 through the exhaust pipe 46 by the exhaust mechanism 47 of the exhaust unit 4.

The process gas supply mechanism 5 has a TiCl ₄ gas supply source 51, an NH ₃ gas supply source 52, a dichlorosilane (DCS) gas supply source 53, a first N ₂ gas supply source 54, a second N ₂ gas supply source 55, and a third N ₂ gas supply source 56. The TiCl ₄ gas supply source 51 supplies TiCl ₄ gas, which is a Ti raw material gas. The NH ₃ gas supply source 52 supplies NH ₃ gas, which is a nitriding gas (reducing gas). The DCS gas supply source 53 supplies DCS gas, which is a Si-containing gas. The first to third N ₂ gas supply sources 54, 55, and 56 supply N ₂ gas as a carrier gas and a purge gas. Note that the carrier gas and the purge gas are not limited to N ₂ gas, and other inert gases such as Ar gas can be used.

One end of a TiCl ₄ gas supply pipe 61 is connected to the TiCl ₄ gas supply source 51. One end of an NH ₃ gas supply pipe 62 is connected to the NH ₃ gas supply source 52. One end of a DCS gas supply pipe 63 is connected to the DCS gas supply source 53. One ends of a first N ₂ gas supply pipe 64, a second N ₂ gas supply pipe 65, and a third N ₂ gas supply pipe 66 are connected to the first N ₂ gas supply source 54, the second N ₂ gas supply source 55, and the third N ₂ gas supply source 56, respectively. The other end of the TiCl ₄ gas supply pipe 61 is connected to the gas introduction hole 45a, the other end of the NH ₃ gas supply pipe 62 is connected to the gas introduction hole 45b, and the other end of the DCS gas supply pipe 63 is connected to the gas introduction hole 45c. The other end of the first _N2 gas supply pipe 64 is connected to the _TiCl4 gas supply pipe 61, the other end of the second _N2 gas supply pipe 65 is connected to the _NH3 gas supply pipe 62, and the other end of the third _N2 gas supply pipe 66 is connected to the DCS gas supply pipe 63. A branch pipe 62a branches off in the middle of the _NH3 gas supply pipe 62, and the other end of the branch pipe 62a merges with the _NH3 gas supply pipe 62. By providing the branch pipe 62a in this manner, it is possible to supply a large flow rate of _NH3 gas. The _TiCl4 gas supply pipe 61, the _NH3 gas supply pipe 62, the branch pipe 62a, and the DCS gas supply pipe 63 are provided with opening and closing valves 71, 72, 72a, and 73, respectively, upstream of the merged portion of the _N2 gas supply pipe. Also, the first _N2 gas supply pipe 64, the second _N2 gas supply pipe 65, and the third _N2 gas pipe 66 are provided with opening and closing valves 74, 75, and 76, respectively. Also, flow rate controllers 81 to 86 are provided upstream of the opening and closing valves of the _TiCl4 gas supply pipe 61, the _NH3 gas supply pipe 62, the DCS gas supply pipe 63, the first _N2 gas supply pipe 64, the second _N2 gas supply pipe 65, and the third _N2 gas pipe 66, respectively. As the flow rate controller, for example, a mass flow controller can be used.

During TiN film formation, the valves 74, 75, and 76 of the first _N2 gas supply pipe 64, the second _N2 gas supply pipe 65, and the third _N2 gas supply pipe 66 are constantly open to constantly supply _N2 gas, and the valves 71, 72, and 72a are operated at high speed with the valve 73 closed, so that ALD film formation can be performed. When DCS gas, which is a Si-containing gas, is to be supplied after film formation, the valves 71, 72, and 72a are closed and the valve 73 is opened.

In addition, the flow rate of _N2 gas may be increased during the purging process by providing piping that branches off from each of the first _N2 gas supply pipe 64, the second _N2 gas supply pipe 65, and the third _N2 gas supply pipe 66 and increases the flow rate of _N2 gas only during purging. The purge gas is not limited to _N2 gas, and may be other inert gas such as Ar gas.

As the Ti source gas, in addition to _TiCl4 , tetra(isopropoxy)titanium (TTIP), titanium tetrabromide ( _TiBr4 ), titanium tetraiodide ( _TiI4 ), tetrakisethylmethylaminotitanium (TEMAT), tetrakisdimethylaminotitanium (TDMAT), tetrakisdiethylaminotitanium (TDEAT), etc. can be used. In addition to _NH3 gas, hydrazine-based gases such as monomethylhydrazine (MMH) can be used as the nitriding gas (reducing gas). In addition to DCS gas, various gases such as those mentioned above can be used as the silicon-containing gas.

The control unit 6 is composed of a computer, and has a main control unit with a CPU, an input device (keyboard, mouse, etc.), an output device (printer, etc.), a display device (display, etc.), and a storage device (storage medium). The main control unit controls the operation of each component, such as opening and closing the opening and closing valves 71-76, adjusting the gas flow rate by the flow rate controllers 81-86, adjusting the pressure inside the chamber 1 by the pressure control valve, and adjusting the temperature of the wafer W by the heater 31. These operations are controlled by a process recipe, which is a control program stored in a storage medium (hard disk, optical disk, semiconductor memory, etc.) built into the storage device.

[Method of forming TiN film using the film forming apparatus of FIG. 3]
Next, a method for forming a TiN film in the film forming apparatus 100 configured as above will be described.
First, the gate valve 27 is opened, and the wafer W is carried into the chamber 1 from the vacuum transfer chamber by the transfer device, and placed on the susceptor 2. As the wafer W, for example, as shown in FIG. 4, one having a patterned _SiO2 film 302 on a Si substrate 301 is used.

After the transfer device is withdrawn, the gate valve 27 is closed and the susceptor 2 is raised to the processing position. Next, _N2 gas is continuously supplied into the processing space S from the first _N2 gas supply source 54, the second N2 gas supply source ₅₅ , and the third _N2 gas supply source 56 to maintain the inside of the chamber 1 at a predetermined reduced pressure, and the temperature of the susceptor 2 is controlled to a predetermined temperature by the heater 31.

Then, while maintaining the state in which _N2 gas is continuously supplied, the opening and closing valves 71, 72, and 72a are operated to sequentially supply _TiCl4 gas as a source gas and _NH3 gas as a nitriding gas (reducing gas) by the ALD method to form a TiN film as a metal-based film on the wafer W. For example, as shown in FIG. 5, a TiN film 303 is formed on a patterned _SiO2 film 302 of the wafer W.

The conditions for this are preferably a temperature of the susceptor 2 of 200 to 600°C and a pressure in the chamber 1 of 266.6 to 13,332.2 Pa (2 to 100 Torr).

After the film formation, the on-off valves 71, 72, and 72a are closed to stop the supply of _TiCl4 gas and _NH3 gas, and the inside of the chamber 1 is purged with _N2 gas.

Thereafter, while the wafer W after the film formation is placed on the susceptor 2, the on-off valve 73 is opened to supply DCS gas, which is a Si-containing gas, into the chamber 1, which is the processing vessel. At this time, _N gas is supplied as a carrier gas from at least the third _N gas supply source 56.

By carrying out the Si-containing gas supply process, which is a post-film formation process, in this manner, the DCS gas, which is a Si-containing gas, is adsorbed onto the surface of the TiN film formed on the wafer W, and as shown in FIG. 6, a Si-containing layer is formed as a surface layer 304 on the surface of the TiN film 303 formed on the wafer W. The Si-containing layer constituting the surface layer 304 may be a Si layer formed by heating a Si-containing gas, or may contain TiSiN formed by the reaction of Si and TiN in Si.

The conditions for supplying DCS gas are preferably a susceptor 2 temperature of 400 to 600°C and a pressure in the chamber 1 of 266.6 to 13,332.2 Pa (2 to 100 Torr). Similar conditions can also be used for other Si-containing gases. In addition, the susceptor temperature is preferably the same as that used when forming the TiN film, from the viewpoint of not reducing throughput.

In this way, the Si-containing gas is adsorbed onto the surface of the TiN film 303 formed on the wafer W to form a surface layer 304, and the wafer W is transported out with the surface of the TiN film 303 not exposed. Therefore, even if the wafer W is exposed to the atmosphere, oxidation of the TiN film 303 is suppressed, and an increase in the resistance of the TiN film 303 can be prevented. In particular, when the thickness of the TiN film 303 is as thin as 5 nm or less, the effect of oxidation becomes greater, and therefore the oxidation suppression effect of supplying DCS gas, which is such a Si-containing gas, becomes even greater.

The supply of the Si-containing gas may be repeated once or multiple times. When the supply of the Si-containing gas is performed once, the amount of adsorption can be controlled by the supply time. In this case, the supply time of the Si-containing gas, for example, DCS gas or SiH ₄ gas, is preferably 1 to 20 sec. Furthermore, by repeating the supply of the Si-containing gas, DCS gas, SiH ₄ gas, etc. multiple times, the amount of adsorption of the DCS gas or SiH ₄ gas can be controlled by the number of times, and the controllability of the layer thickness of the surface layer 304 can be improved. Therefore, the resistance of the TiN film can be lowered. In this case, the supply time of the DCS gas or SiH ₄ gas, etc. once is preferably 0.05 to 4 sec, and the number of times (number of cycles) of the supply of the DCS gas or SiH ₄ gas, etc. is preferably in the range of 1 to 5 times. The same applies when other Si-containing gases are used. Furthermore, when the supply of the Si-containing gas is repeated multiple times, it is preferable to purge the inside of the chamber 1 with N ₂ gas between the supply of the Si-containing gas.

In this case, the specific gas supply sequence of the TiN film forming process and the Si-containing gas supply process is as shown in Fig. 7 and Fig. 8. Here, the case where DCS gas or _SiH4 gas is used as the Si-containing gas is shown. Fig. 7 is a timing chart when DCS gas or _SiH4 gas, which is the Si-containing gas, is supplied once (one cycle), and Fig. 8 is a timing chart when DCS gas or _SiH4 gas is supplied multiple times (multiple cycles).

In the Si-containing gas supply process, which is a post-film formation process, NH ₃ gas may be supplied. In this case, NH ₃ gas may be supplied after supplying DCS gas or SiH ₄ gas, which is a Si-containing gas, or DCS gas or SiH ₄ gas and NH ₃ gas may be alternately supplied multiple times. By supplying DCS gas or SiH ₄ gas and NH ₃ gas, a SiN layer can be formed as the surface layer 304. By supplying these alternately multiple times, the uniformity of the film thickness can be further improved. In this case, the specific gas supply sequence of the TiN film formation process and the Si-containing gas supply process is, for example, as shown in the timing chart in FIG. 9. FIG. 9 shows an example in which, after the film formation process is completed, TiCl ₄ gas is stopped, purging is performed, and then NH ₃ gas and DCS gas or SiH ₄ gas are alternately supplied multiple times.

After the Si-containing gas supply process, the open/close valve 73 is closed to stop the supply of DCS gas, which is the Si-containing gas, and the chamber 1 is purged with _N2 gas. Next, the gate valve 27 is opened, and the wafer W is unloaded through the load/unload port 26.

In fact, after forming a TiN film with a thickness of 3 to 5 nm by the ALD method, the change in resistivity after leaving it in the atmosphere was investigated for the cases where the Si-containing gas supply process was not performed and where DCS gas was supplied as the Si-containing gas supply process under various conditions. Figure 10 shows the relationship between the DCS gas flow rate and the resistivity of the TiN film, and Figure 11 shows the relationship between the DCS gas supply time and the resistivity of the TiN film. The temperature of the DCS gas supply process was 450 to 500°C, the pressure was in the range of 266.6 to 1199.9 Pa (2 to 9 Torr), Figure 7 shows the case where the DCS gas supply time was 0.05 sec, and Figure 8 shows the case where the DCS gas flow rate was 30 sccm. As shown in these figures, the resistivity (μΩ cm) after leaving it in the atmosphere was reduced by performing the Si-containing gas supply process, and the effect of suppressing the oxidation of the surface of the TiN film by the DCS gas supply process was confirmed. It was also confirmed that the resistivity decreased with an increase in the DCS gas flow rate and the length of time the DCS gas was supplied, with a flow rate of 100 sccm reducing the resistivity by 26.8% and a time of 10 sec reducing the resistivity by 37.8%.

Next, the sheet resistance (Ω/sq.) of the TiN film after being left in the atmosphere was measured for the case where SiH ₄ gas was supplied once (1 cycle) as the Si-containing gas supply process and the case where SiH ₄ gas was supplied 5 times (5 cycles) with purging in between. For comparison, the sheet resistance was also measured for the case where SiH ₄ gas was not supplied after the TiN film was formed. Here, the supply time and flow rate of SiH ₄ gas per one time were set to 0.05 sec and 50 sccm, respectively, and the temperature of the Si-containing gas supply process was set to 450 to 700°C, and the pressure was set to 266.6 to 1199.9 Pa (2 to 9 Torr). The sheet resistance and its uniformity at that time are shown in FIG. 12.

12, when the Si-containing gas supply step was not performed, the average value of the sheet resistance was 44.4 Ω/sq. and the uniformity was 3.9%, whereas when the number of times (cycles) of SiH ₄ gas was supplied (1 cycle), the average value of the sheet resistance was 39.1 Ω/sq. and the uniformity was 1.2%, and when the number of times (cycles) of SiH ₄ gas was supplied (5 cycles), the average value of the sheet resistance was 38.9 Ω/sq. and the uniformity was 1.0%. That is, the supply of SiH ₄ gas improved the resistivity and its uniformity, and the supply of SiH ₄ gas multiple times further improved the resistivity and its uniformity.

Next, the sheet resistance (Ω/sq.) _of the TiN film after being left in the atmosphere was measured for the case where SiH ₄ gas and NH ₃ gas were supplied once each (1 cycle) as the Si-containing gas supply process, and the _case where SiH 4 gas and NH 3 gas were supplied alternately 5 times (5 cycles) with purging in between. Here, the supply time and flow rate of SiH ₄ gas per time were 0.05 sec and 50 sccm, respectively, and the supply time and flow rate of NH ₃ gas per time were 0.05 sec and 600 sccm, respectively. In addition, the temperature of the Si-containing gas supply process was 450 to 700°C, and the pressure was in the range of 266.6 to 1199.9 Pa (2 to 9 Torr). The sheet resistance and its uniformity at that time are shown in FIG. 13. FIG. 13 also shows the results when the Si-containing gas supply process of FIG. 12 is not performed.

13, when the Si-containing gas supply process is not performed, the average sheet resistance is 44.4 Ω/sq. and the uniformity is 3.9%, while when _SiH4 gas and _NH3 gas are supplied once, the average sheet resistance is 39.7 Ω/sq. and the uniformity is 1.2%, and when _SiH4 gas and _NH3 gas are supplied five times, the average sheet resistance is 39.1 Ω/sq. and the uniformity is 1.2%. That is, the sheet resistance and its uniformity are improved by supplying _SiH4 gas and _NH3 gas, and the sheet resistance is further improved by supplying _SiH4 gas and _NH3 gas multiple times.

After the Si-containing gas is supplied to form the surface layer 304 of the TiN film 303, the wafer W is taken out into the atmosphere, and then, as shown in FIG. 14, the next film formation process, for example, the formation of a SiGe film 305, is performed in another film formation apparatus. Then, after necessary post-processing is performed, the desired semiconductor device (semiconductor device) is obtained. At this time, because the Si-containing gas is supplied to the surface of the TiN film 303 to form the surface layer 304 containing Si, oxidation of the TiN film 303 is suppressed and the resistivity is maintained low. As a result, good device characteristics are obtained.

The film formed in the next process is the SiGe film 305, which is a Si-containing layer, and therefore has a high affinity with the Si-containing surface layer 304 formed to suppress oxidation. In addition, since the SiGe film is formed in the next process on the Si-containing surface layer 304, effects such as a shortened incubation time can be obtained when forming a SiGe film by a general CVD method.

<Other applications>
Although the embodiments have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

For example, in the above embodiment, the description has been focused on the case where a TiN film is formed as a metal-based film by the ALD method, but as mentioned above, the present invention can be applied to any metal film or metal compound film whose characteristics may be deteriorated by oxidation, and the film formation method is not limited to the ALD method.

The deposition apparatus in FIG. 3 is an example of an apparatus for ALD deposition of TiN films, but the deposition apparatus in FIG. 3 can also be applied to deposition of other metal-based films. The deposition apparatus shown in FIG. 3 is merely an example, and may be any deposition apparatus, such as a CVD deposition apparatus or a PVD deposition apparatus, as long as it can perform deposition processing and supply Si-containing gas into the processing vessel (chamber). The deposition apparatus in FIG. 3 is a single-wafer type, but it may be a batch type deposition apparatus that deposits films on multiple substrates at once, such as a vertical apparatus. It may also be a semi-batch type deposition apparatus that places multiple substrates on a stage and performs deposition processing.

In addition, in the above embodiment, a semiconductor wafer is used as an example of the substrate, but the substrate is not limited to a semiconductor wafer and may be other substrates such as a glass substrate used in an FPD (flat panel display) or a ceramic substrate.

REFERENCE SIGNS LIST 1; chamber 2; susceptor 3; shower head 4; exhaust unit 5; gas supply mechanism 6; control unit 51; _TiCl4 gas supply source 52; _NH3 gas supply source 53; DCS gas supply source 54, 55, 56; _N2 gas supply source 100; film forming apparatus 201; substrate 202; metal-based film 203; surface layer 301; Si substrate 302; _SiO2 film 303; TiN film 304; surface layer W; semiconductor wafer (substrate)

Claims (24)

Providing a substrate in a processing chamber;
forming a metal film on the substrate in the processing chamber;
thereafter, supplying a Si-containing gas into the processing vessel with the substrate disposed in the processing vessel, and allowing the Si-containing gas to be adsorbed onto the metal-based film, thereby forming a surface layer on the surface of the metal-based film that contains Si and suppresses oxidation of the metal film when the substrate having the metal-based film formed thereon is unloaded from the processing vessel ;
(However, excluding the case where the metal-based film is a Ti film and a TiN film and the surface layer is a TiSiN film) . 2. The film forming method according to claim 1, wherein the substrate temperature is in the range of 400 to 600° C. in the step of forming the surface layer . The film forming method according to claim 1 or 2, wherein the Si-containing gas is at least one of a silane-based compound, a chlorosilane-based compound, and an organosilane-based compound. The film forming method according to claim 3, wherein the Si-containing gas is at least one of dichlorosilane, silane, and disilane. The film forming method according to claim 1 , wherein the step of forming the surface layer comprises supplying the Si-containing gas a plurality of times. The film forming method according to claim 1 , wherein the step of forming the surface layer comprises supplying the Si-containing gas and a reaction gas that reacts with the Si-containing gas. The film forming method according to claim 6 , wherein the step of forming the surface layer comprises alternately supplying the Si-containing gas and the reaction gas a plurality of times. The film forming method according to any one of claims 1 to 7, wherein the process of forming the metal-based film is performed by either an ALD method, a CVD method, or a PVD method. The film forming method according to any one of claims 1 to 8, wherein the metal film is any one of a Ti film, a TiN film, a Ta film, a TaN film, a W film, an Al film, a Mo film, a Ru film, a Co film, and a Ni film. The film forming method according to claim 1, wherein the metal film is a TiN film, and the process of forming the metal film is performed by an ALD method. The film forming method according to claim 10, wherein the surface layer includes TiSiN. The film forming method according to claim 10 or 11, wherein the Si-containing gas is dichlorosilane. The film forming method according to claim 10 , wherein the step of forming the surface layer comprises supplying the Si-containing gas a plurality of times. 14. The film forming method according to claim 10, wherein the TiN film is formed by using a Ti-containing gas and an _NH3 gas, and the step of supplying the Si-containing gas supplies the Si-containing gas and an _NH3 gas. The film forming method according to claim 14 , wherein the step of forming the surface layer comprises alternately supplying the Si-containing gas and the NH ₃ gas a plurality of times. The film forming method according to any one of claims 10 to 15, wherein the substrate is a semiconductor substrate having a patterned _SiO2 film formed thereon. a processing vessel in which a substrate is accommodated;
a gas supply mechanism for supplying a gas for forming a metal film and a Si-containing gas into the processing chamber;
an exhaust mechanism for exhausting the inside of the processing vessel;
A heating mechanism for heating the substrate;
A control unit;
having
The control unit is
providing a substrate in the processing chamber;
forming the metal-based film on the substrate in the processing chamber;
thereafter, supplying a Si-containing gas into the processing vessel with the substrate disposed in the processing vessel , and allowing the Si-containing gas to be adsorbed onto the metal-based film, thereby forming a surface layer on the surface of the metal-based film that contains Si and suppresses oxidation of the metal-based film when the substrate having the metal-based film formed thereon is unloaded from the processing vessel;
a gas supply mechanism, an exhaust mechanism, and a heating mechanism so that the above-mentioned is performed (except when the metal-based film is a Ti film and a TiN film and the surface layer is a TiSiN film) . Providing a substrate in a processing chamber of a first film forming apparatus;
forming a metal film on the substrate in the processing chamber;
thereafter, supplying a Si-containing gas into the processing vessel with the substrate disposed in the processing vessel;
unloading the substrate from the processing chamber and depositing a Si-containing film on the substrate by a second deposition apparatus;
having
The step of supplying a Si-containing gas includes forming a surface layer containing Si on the surface of the metal-based film by adsorbing the supplied Si-containing gas onto the surface of the metal-based film so as to suppress oxidation of the metal-based film. The method for manufacturing a semiconductor device according to claim 18, wherein the step of supplying the Si-containing gas includes supplying the Si-containing gas multiple times. The method for manufacturing a semiconductor device according to claim 18, wherein the step of supplying the Si-containing gas supplies the Si-containing gas and a reaction gas that reacts with the Si-containing gas. The method for manufacturing a semiconductor device according to claim 20, wherein the step of supplying the Si-containing gas includes alternately supplying the Si-containing gas and the reaction gas multiple times. The method for manufacturing a semiconductor device according to any one of claims 18 to 21, wherein the Si-containing film is formed on the surface of the surface layer. The method for manufacturing a semiconductor device according to any one of claims 18 to 21, wherein the metal film is a TiN film and the Si-containing film is a SiGe film. 24. The method for manufacturing a semiconductor device according to claim 23, wherein the substrate is a semiconductor substrate having a patterned _SiO2 film formed thereon.

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