JP2021110030A - Film forming method, film forming device, and method for manufacturing semiconductor device - Google Patents

Abstract

To provide a film forming method, a film forming device, and a method for manufacturing a semiconductor device with which it is possible to suppress oxidation of a film surface when forming a metal-based film.SOLUTION: The film forming method includes the steps of: providing a substrate inside a processing container; forming a metal-based film on the substrate inside the processing container; and then supplying Si-containing gas into the processing container while the substrate is provided inside the processing container.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a film forming method, a film forming apparatus, and a method for manufacturing a semiconductor apparatus.

In the manufacturing process of semiconductor devices, for example, metal-based films such as TiN films are used for various purposes such as electrodes such as lower electrodes of DRAMs and barrier membranes. A general thin film forming technique is used for forming a metal-based film such as a TiN film, and Patent Document 1 states that a TiN film is formed by an atomic layer deposition method (ALD method). Has been described.

Japanese Unexamined Patent Publication No. 2015-78418

The present disclosure provides a film forming method, a film forming apparatus, and a method for manufacturing a semiconductor apparatus capable of suppressing oxidation of the film surface when forming a metal-based film.

The film forming method according to one aspect of the present disclosure includes a step of providing a substrate in the processing container, a step of forming a metal-based film on the substrate in the processing container, and then the step of forming the metal-based film in the processing container. The step of supplying the Si-containing gas into the processing container with the substrate provided is included.

According to the present disclosure, there are provided a film forming method, a film forming apparatus, and a semiconductor manufacturing method capable of suppressing oxidation of the film surface when forming a metal film.

It is a flowchart which shows the film formation method which concerns on one Embodiment. It is a process sectional view which shows the film forming method which concerns on one Embodiment. It is sectional drawing which shows an example of the film-forming apparatus when the film-forming method of one Embodiment is applied to the film-forming of a TiN film. It is sectional drawing which shows the structural example of the semiconductor wafer which the film-forming process is performed by the apparatus of FIG. FIG. 5 is a cross-sectional view showing a state in which a TiN film is formed on the semiconductor wafer of FIG. FIG. 5 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 a DCS gas which is a Si-containing gas into the chamber after forming the TiN film. It is a timing chart which shows the specific gas supply sequence of the film formation process of a TiN film and the Si-containing gas supply process, _{and is the case where SiH 4} gas is supplied once (1 cycle) as a Si-containing gas. It is a timing chart which shows the specific gas supply sequence of the film formation process of a TiN film and the Si-containing gas supply process, _{and is the case where SiH 4} gas is supplied a plurality of times (multiple cycles) as a Si-containing gas. This is a specific gas supply sequence of the TiN film forming process and the Si-containing gas supply process, and is a case where SiH ₄ gas and NH ₃ gas are alternately supplied a plurality of times. It is a figure which shows the relationship between the DCS gas flow rate and the specific resistance of a TiN film. It is a figure which shows the relationship between the DCS gas supply time and the specific resistance of a TiN film. _{When the SiH 4} gas is supplied for 1 cycle as the Si-containing gas supply step, _{when the SiH 4} gas is supplied for 5 cycles with a purge in between, and when the SiH ₄ gas is not supplied after the TiN film is formed. It is a figure which shows the result of having measured the sheet resistance of a TiN film and the uniformity thereof. As the Si-containing gas supply step, the case where SiH ₄ gas and NH ₃ gas are supplied for 1 cycle, the case where SiH ₄ gas is supplied and NH ₃ gas is supplied for 5 cycles, and the case where SiH is formed after the TiN film is formed. ₄ It is a figure which shows the result of having measured the sheet resistance of a TiN film and the uniformity thereof in the case where the gas is not supplied. It is sectional drawing which shows the state which formed the SiGe film after the surface layer was formed on the surface of a TiN film.

Hereinafter, embodiments will be described with reference to the accompanying drawings.

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

In step 1, the substrate 201 for forming a metal-based film is arranged in the processing container of the film forming apparatus to prepare for the film formation. The substrate 201 is not particularly limited, but a semiconductor substrate (semiconductor wafer) having a semiconductor substrate such as silicon is exemplified. The substrate 201 in this case may be the semiconductor substrate itself, or may have one or more films having a desired function formed on the semiconductor substrate.

Examples of the metal-based film 202 formed on the substrate 201 in step 2 include a metal film and a metal compound film whose characteristics may deteriorate due to oxidation. Specific examples include Ti film, TiN film, Ta film, TaN film, W film, Al film, Mo film, Ru film, Co film, and Ni film.

The film forming method of the metal-based film 202 is not particularly limited, and thin film forming techniques such as the ALD method, the CVD method, and the PVD method are exemplified. From the viewpoint of obtaining good step coverage, the ALD method is preferable.

Step 3 is a post-film formation process in which the Si-containing gas is supplied into the processing container after the metal film 202 is formed. By supplying the Si-containing gas, the Si-containing gas is adsorbed on the surface of the metal-based film, and the Si-containing surface layer 203 is formed.

_{Ammonia (NH 3} ), which is a reaction gas that reacts with another gas, for example, 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, and examples thereof include silane compounds, chlorosilane compounds, and organic silane compounds. Examples of the silane compound include silane (monosilane) and disilane. Examples of the chlorosilane compound include dichlorosilane, monochlorosilane, trichlorosilane, silicontetrachloride, and hexachlorodisilane. Examples of the organic silane compound include aminosilane compounds such as butylaminosilane, Vistashaributylaminosilane, and dimethylaminosilane. Among these, at least one of dichlorosilane, silane, and disilane, which are generally used in the semiconductor manufacturing process, can be preferably used.

When only the Si-containing gas or the Si-containing gas and the inert gas are supplied, the Si-containing gas can be thermally decomposed to form a Si layer as the surface layer 203. The surface layer 203 may have a reaction layer in which Si and the base have reacted. When a reaction gas is supplied in addition to the Si-containing gas, a Si compound layer can 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 can be formed as the surface layer 203.

The temperature and pressure conditions in the step of supplying the Si-containing gas in step 3 differ 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 266.6 to 1333.2 Pa. It is preferably in the range of (2 to 100 Torr).

The supply of the Si-containing gas may be repeated once or a plurality of times. When the Si-containing gas is supplied once, the adsorption amount can be controlled by the supply time. In this case, the supply time of the Si-containing gas is preferably 0.05 to 20 sec. Further, by repeating the supply of the Si-containing gas a plurality of times, the adsorption amount 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 time for supplying the Si-containing gas at one time is preferably 0.05 to 4 sec, and the number of times the Si-containing gas is supplied (number of cycles) is preferably in the range of 1 to 5 times. Further, it is preferable to perform purging with an inert gas while supplying the Si-containing gas.

When the reaction gas is supplied in addition to the Si-containing gas, the reaction gas may be supplied after the Si-containing gas is supplied, or the Si-containing gas and the reaction gas may be alternately supplied a plurality of times. .. By alternately supplying the surface layer 203 a plurality of times, the Si compound layer can be formed as the surface layer 203 with good layer thickness controllability. The Si-containing gas and the reaction gas may be supplied at the same time. A SiN layer can be formed as the surface layer 203 by using, _{for example, NH 3} gas as the reaction gas.

When the surface layer 203 is formed by supplying the Si-containing gas, the amount of the Si-containing gas adsorbed is not particularly limited, and the oxidation suppressing effect can be obtained with one or more molecular layers. If the adsorption amount of the Si-containing gas becomes too large, there is a concern that the characteristics may be affected. Therefore, the adsorption amount is preferably 15 nm or less in terms of film thickness, and the thickness of the surface layer 203 is 0.5 to 0.5 to The range of 1 nm is preferable. Similarly, when a Si-containing gas and a reaction gas are supplied 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 step of supplying the Si-containing gas after forming the metal film in this way will be described below.

After the metal film is formed, the substrate is carried out from the processing container and used for the next step. If the substrate is carried out to the atmosphere before the next process, the formed metal film is exposed to oxygen and moisture in the atmosphere, so that it is oxidized from the surface in the bulk direction, and the characteristics deteriorate. do. For example, the resistance of the membrane increases. In particular, when the film thickness is thin, the influence of oxidation from the surface becomes large, so that the deterioration of the characteristics becomes remarkable.

Therefore, after forming a metal-based film 202 on the substrate 201 in the processing container, the Si-containing gas is supplied into the processing container to adsorb the Si-containing gas on the surface of the metal-based film 202 and contain Si. The surface layer 203 to be formed is formed. As a result, the substrate is carried out in a state where the surface of the metal-based film 202 is not exposed, so that oxidation of the metal-based film 202 is suppressed.

The next step may be carried out in another processing container of the vacuum system, but even in that case, the metal-based film is slightly oxidized by oxygen and moisture in the vacuum transfer system, so it depends on the step of supplying the Si-containing gas. The antioxidant effect is effective.

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

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

After the step of supplying the Si-containing gas, the substrate is carried out from the processing container, and the next film forming step is carried out by another film forming apparatus. At this time, since a surface layer containing Si is formed on the surface of the metal-based film on the substrate, the affinity is high if the next film forming step is a step of forming a Si-containing film. At this time, since Si is present on the surface on which the Si-containing film is formed, it can have a good effect such that the incubation time when the Si-containing film is formed is shortened.

<Application of TiN film to film formation>
Next, the film formation of the TiN film will be described as a specific application example.
The TiN film as a metal-based film is used as a barrier membrane or an electrode, and is required to have low electrical resistance. For the formation of a TiN film, the ALD method, which can obtain a film of good film quality with high step coverage, is often used. After the TiN film is formed, the next step of the film formation process, for example, the formation of the SiGe film is performed. In that case, since the film formation of both is performed by different devices, after the TiN film is formed, It is carried out into the atmosphere. At this time, there arises a problem that it is difficult to obtain good device characteristics because the TiN film is oxidized by moisture and oxygen in the atmosphere and the resistance is increased. Therefore, a step of supplying the Si-containing gas is carried out to form a surface layer on the surface of the TiN film and suppress the oxidation of the TiN film after the substrate is carried out from the processing container.
Hereinafter, a specific description will be given.

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

The film forming apparatus 100 includes a chamber 1 which is a processing container, a susceptor (board 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 substantially cylindrical shape. A carry-in / out port 26 for loading / unloading a semiconductor wafer (hereinafter, simply a wafer) W, which is a substrate, is formed on the side wall of the chamber 1 by a transport mechanism (not shown) for a vacuum transport chamber (not shown). The carry-in outlet 26 can be opened and closed by the gate valve 27. An annular exhaust duct 28 having a rectangular cross section is provided on the main body of the chamber 1. A slit 28a is formed in the exhaust duct 28 along the inner peripheral surface. Further, an exhaust port 28b is formed on the outer wall of the exhaust duct 28. A top 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 top wall 29 and the exhaust duct 28 is airtightly sealed with a seal ring 30.

The susceptor 2 is for placing the wafer W, which is a substrate, in the chamber 1, and has a disk shape having a size corresponding to the wafer W and is provided horizontally. The susceptor 2 is supported by the support member 33. A heater 31 for heating the wafer W is embedded in the susceptor 2. The heater 31 is supplied with power from a heater power supply (not shown) to generate heat. Then, by controlling the output of the heater 31, the wafer W is controlled to a predetermined temperature. The susceptor 2 is provided with a ceramic cover member 32 so as to cover the outer peripheral region of the wafer mounting surface and the side surface.

The support member 33 that supports the susceptor 2 extends below the chamber 1 from the center of the bottom surface of the susceptor 2 through a hole formed in the bottom wall of the chamber 1, and its lower end is connected to the elevating mechanism 34. The elevating mechanism 34 allows the susceptor 2 to move up and down via the support member 33 between the processing position shown in FIG. 3 and the transfer position where the wafer can be conveyed, which is indicated by the alternate long and short dash line below the processing position. Further, a flange portion 35 is attached to the lower position of the support member 33 of the chamber 1, and the atmosphere inside the chamber 1 is partitioned from the outside air between the bottom surface of the chamber 1 and the collar portion 35 to form a susceptor 2. A bellows 36 that expands and contracts as the vehicle moves up and down is provided.

Near the bottom surface of the chamber 1, three wafer support pins 37 (only two are shown) are provided so as to project upward from the elevating plate 37a. The wafer support pin 37 can be raised and lowered via the raising and lowering plate 37a by the raising and lowering mechanism 38 provided below the chamber 1, and is inserted into the through hole 22 provided in the susceptor 2 at the transport position to be inserted into the susceptor 2. It is possible to sink into the upper surface of the. As a result, the wafer W is delivered between the wafer transfer mechanism (not shown) and the susceptor 2.

The shower head 3 is for supplying the processing gas into the chamber 1 in a shower shape, is provided at the upper part of the chamber 1 so as to face the susceptor 2, and has substantially the same diameter as the susceptor 2. .. The shower head 3 has a main body 39 fixed to the top wall 29 of the chamber 1 and a shower plate 40 connected under 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 gas dispersion member 42. The gas dispersion member 42 is connected to one end of each of a plurality of gas supply paths 43 provided in the main body 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. Further, in the central portion of the main body portion 39, three gas introduction holes 45a, 45b, 45c penetrating from the upper surface thereof to the diffusion portion 44 are provided.

An annular protrusion 40b protruding downward is formed on the peripheral edge of the shower plate 40, and a gas discharge hole 40a is formed on the flat surface inside the annular protrusion 40b of the shower plate 40. When the susceptor 2 is present at 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. Will be done.

The exhaust unit 4 includes an exhaust pipe 46 connected to the exhaust port 28b of the exhaust duct 28, and an exhaust mechanism 47 connected to the exhaust pipe 46 and having a vacuum pump, a pressure control valve, and the like. At the time of processing, the 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 processing gas supply mechanism 5 includes 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, and a second N ₂ gas supply source 55. When, and a second 3N ₂ gas supply source 56. The TiCl _{4 gas supply source 51 supplies TiCl 4} gas, which is a Ti raw material gas. NH ₃ gas supply source 52 supplies the NH ₃ gas is a gas nitriding (reducing gas). The DCS gas supply source 53 supplies DCS gas, which is a Si-containing gas. First through 3N ₂ gas supply source 54, 55, 56 supplies a _{N 2} gas as a carrier gas and a purge gas. As the carrier gas and the purge gas is not limited to N ₂ gas, it is possible to use another inert gas such as Ar gas.

_{One end of the TiCl 4} gas supply pipe 61 is connected to the SiCl ₄ gas supply source 51. _{One end of the NH 3} gas supply pipe 62 is connected to the NH ₃ gas supply source 52. One end of the DCS supply pipe 63 is connected to the DCS gas supply source 53. The 1N ₂ gas supply source 54, the first 2N ₂ gas supply source 55 and the 3N ₂ gas supply source 56, respectively, the 1N ₂ gas supply pipe 64, the 2N ₂ gas supply pipe 65 and the 3N ₂ gas, One end of the supply pipe 66 is connected. 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 gas. It is connected to the introduction hole 45c. The other end of the 1N ₂ gas supply pipe 64 is connected to the TiCl ₄ gas supply line 61, the other end of the 2N ₂ gas supply pipe 65 is connected to the NH ₃ gas supply line 62, the 3N ₂ gas The other end of the supply pipe 66 is connected to the DCS gas supply pipe 63. The _{branch pipe 62a branches in the middle of the NH 3} gas supply pipe 62, and the other end of the branch pipe 62a _{joins the NH 3} gas supply pipe 62. By providing such a branch pipe 62a, it is possible to supply the NH ₃ gas at a high flow rate. The TiCl ₄ gas supply pipe 61, the NH ₃ gas supply pipe 62, the branch pipe 62a, and the DCS gas supply pipe 63 have on-off valves 71, 72, 72a, and 73 on the upstream side of the confluence _{of the N 2 gas supply pipes, respectively.} It is provided. Further, the first N ₂ gas supply pipe 64, the second N ₂ gas supply pipe 65, and the third N ₂ gas pipe 66 are provided with on-off valves 74, 75, and 76, respectively. Further, upstream of the on-off valve of _{the TiCl 4} gas supply pipe 61, the NH ₃ gas supply pipe 62, the DCS gas supply pipe 63, the 1st N ₂ gas supply pipe 64, the _2nd N 2 gas supply pipe 65, and the 3N _{2 gas pipe 66.} Flow controllers 81 to 86 are provided on each side. As the flow rate controller, for example, a mass flow controller can be used.

Then, when the TiN film formation, the second 1N ₂ gas supply pipe 64, and the normally open on-off valve 74, 75 and 76 of the 2N ₂ gas supply pipe 65 and the 3N ₂ gas supply pipe 66, _{N 2} ALD film formation can be performed by operating the on-off valves 71, 72, and 72a at high speed while the gas is always supplied and the on-off valve 73 is closed. When DCS gas, which is a Si-containing gas, is supplied after the film formation, the valves 71, 72, 72a are closed and the open / close valve 73 is opened.

In the purging process, a pipe for branching from the first N ₂ gas supply pipe 64, the second N ₂ gas supply pipe 65, and the third N ₂ gas supply pipe 66 to _{increase the flow rate of the N 2 gas only when purging is provided.} At the same time, the N ₂ gas flow rate may be increased. Further, the purge _{gas is not limited to the N 2} gas, and may be another inert gas such as Ar gas.

_{In addition to TiCl 4} , the Ti raw material gas includes tetra (isopropoxy) titanium (TTIP), titanium tetrabromide (TiBr ₄ ), titanium tetraiodide (TiI ₄ ), tetrakisethylmethylaminotitanium (TEMAT), and tetrakisdimethyl. Amino titanium (TDMAT), tetrakis diethylamino titanium (TDEAT) and the like can also be used. As the nitriding gas (reducing gas), other NH ₃ gas may be used hydrazine gas, such as monomethyl hydrazine (MMH) and the like. Further, as the silicon-containing gas, in addition to the DCS gas, various gases as described above can be used.

The control unit 6 is composed of a computer, and includes a main control unit equipped 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). Have. The main control unit may, for example, open / close the on / off valves 71 to 76, adjust the gas flow rate by the flow rate controllers 81 to 86, adjust the pressure in the chamber 1 by the pressure control valve, adjust the temperature of the wafer W by the heater 31, and the like. Controls the operation of each component of. The control of these operations is executed by a processing recipe which is a control program stored in a storage medium (hard disk, optical desk, semiconductor memory, etc.) built in the storage device.

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

After retracting the transport device, the gate valve 27 is closed and the susceptor 2 is raised to the processing position. _{Next, N 2} gas is continuously supplied into the processing space S from 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, and the inside of the chamber 1 is in a predetermined depressurized state. The temperature of the susceptor 2 is controlled to a predetermined temperature by the heater 31.

Then, while maintaining the state of being continuously supplied _{N 2} gas, by operating the opening and closing valve 71,72,72A, sequential and TiCl ₄ gas as a source gas, NH ₃ gas is a gas nitriding (reducing gas) A TiN film, which is a metal-based film, is formed on the wafer W by the ALD method. For example, as shown in FIG. 5, the TiN film 303 is formed on _{the patterned SiO 2 film 302 of the wafer W.}

The conditions at this time are preferably such that the temperature of the susceptor 2 is 200 to 600 ° C. and the pressure in the chamber 1 is 266.6 to 133332.2 Pa (2 to 100 Torr).

After the film formation, the on-off valves 71, 72, 72a are closed _{to stop the supply of TiCl 4} gas and NH ₃ gas, and the inside of the chamber 1 is _{purged with N 2} gas.

After that, with the wafer W after film formation still placed on the susceptor 2, the open / close valve 73 is opened to supply DCS gas, which is a Si-containing gas, into the chamber 1 which is a processing container. _{At this time, N 2} gas as a carrier gas is supplied from at least the third N _{2 gas supply source 56.}

By carrying out the Si-containing gas supply step which is the post-film formation treatment in this way, DCS gas, which is a Si-containing gas, is adsorbed on the surface of the TiN film formed on the wafer W, and as shown in FIG. 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 contains TiSiN formed by the reaction of Si and TiN in Si. You may.

The conditions for supplying the DCS gas are preferably such that the temperature of the susceptor 2 is 400 to 600 ° C. and the pressure in the chamber 1 is 266.6 to 133332.2 Pa (2 to 100 Torr). Conditions similar to this can be used for other Si-containing gases. Further, the susceptor temperature is preferably the same temperature as when the TiN film is formed, from the viewpoint of not lowering the throughput.

In this way, the Si-containing gas is adsorbed on the surface of the TiN film 303 formed on the wafer W to form the surface layer 304, so that the wafer W is carried out in a state where the surface of the TiN film 303 is not exposed. Will be done. Therefore, even if the wafer W is exposed to the atmosphere, the 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 film thickness of the TiN film 303 is as thin as 5 nm or less, the influence of oxidation becomes large, so that the effect of suppressing oxidation by supplying DCS gas, which is a Si-containing gas, becomes higher.

The supply of the Si-containing gas may be repeated once or a plurality of times. When performing the supply of Si-containing gas in one, it is possible to control the amount of adsorption in the supply time, in this case, Si-containing gas, for example DCS gas and SiH ₄ supply time such as gas, 1～20Sec Is preferable. Further, by repeating the supply of the Si-containing gas, the DCS gas, the SiH ₄ gas, etc. a plurality of times _{, the adsorption amount of the DCS gas, the SiH 4} gas, etc. can be controlled by the number of times, and the layer thickness of the surface layer 304 can be controlled. Can be enhanced. Therefore, the resistance of the TiN film can be made lower. In this case, once the supply time such as DCS gas and SiH ₄ gas, 0.05～4Sec ,, DCS gas and SiH ₄ supply count (number of cycles), such as gas, from 1 to 5 times is preferable .. The same applies when another Si-containing gas is used. When the supply of the Si-containing gas is repeated a plurality of times, it is preferable to purge the inside of the chamber 1 _{with the N 2 gas during the supply of the Si-containing gas.}

Specific gas supply sequences of the TiN film forming step and the Si-containing gas supply step in this case are shown in FIGS. 7 and 8, for example. Here it is shown a case of using the DCS gas or SiH ₄ gas as the Si-containing gas. _{FIG. 7 is a timing chart when DCS gas or SiH 4} gas, which is a Si-containing gas, is supplied once (1 cycle), and FIG. 8 is a timing when DCS gas or SiH ₄ gas is supplied multiple times (multiple cycles). It is a chart.

During Si-containing gas supply step is deposition aftertreatment may supply the NH ₃ gas. _{In this case, the NH 3} gas may be supplied after supplying the _{DCS gas or the SiH 4} gas which is the Si-containing gas, or the DCS gas or the SiH ₄ gas and the NH ₃ gas may be alternately supplied a plurality of times. May be good. A SiN layer can be formed as the surface layer 304 by supplying DCS gas or SiH ₄ gas and NH _{3 gas.} By alternately supplying these a plurality of times, the uniformity of the film thickness can be further improved. The specific gas supply sequence of the TiN film forming step and the Si-containing gas supply step in this case is, for example, as shown in the timing chart shown in FIG. FIG. 9 shows an example in which the TiCl ₄ gas is stopped after the film forming process is completed, the gas is purged, and then the NH ₃ gas and the DCS gas or the SiH ₄ gas are alternately supplied a plurality of times.

After Si-containing gas supply step, by closing the opening and closing valve 73 to stop the supply of the DCS gas is Si-containing gas, in the chamber 1 is purged by the N ₂ gas. Next, the gate valve 27 is opened, and the wafer W is carried out through the carry-in / out port 26.

In the case where the Si-containing gas supply step is not actually performed after the TiN film having a film thickness of 3 to 5 nm is actually formed by the ALD method, and the case where the DCS gas is supplied as the Si-containing gas supply step under various conditions. , The change in resistivity after being left in the atmosphere was investigated. FIG. 10 is a diagram showing the relationship between the DCS gas flow rate and the specific resistance of the TiN film, and FIG. 11 is a diagram showing the relationship between the DCS gas supply time and the specific resistance of the TiN film. The temperature of the DCS gas supply process is 450 to 500 ° C., the pressure is in the range of 266.6 to 1199.9 Pa (2 to 9 Torr), and FIG. 7 shows the case where the DCS gas supply time is 0.05 sec. FIG. Is the case where the DCS gas flow rate is 30 sccm. As shown in these figures, by carrying out the Si-containing gas supply step, the specific resistance (μΩ · cm) after being left in the atmosphere is reduced, and the surface of the TiN film is oxidized by the DCS gas supply step. The suppressive effect was confirmed. Further, as the DCS gas flow rate increases and the DCS gas supply time becomes longer, the specific resistance decreases. By setting the flow rate to 100 sccm, the specific resistance is reduced by 26.8%, and by setting the time to 10 sec, the specific resistance is increased. It was confirmed that the reduction was 37.8%.

Next, as a Si-containing gas supply step, when the SiH ₄ gas is supplied once (1 cycle) and when the SiH ₄ gas is supplied 5 times (5 cycles) with a purge in between, it is introduced into the atmosphere. The sheet resistance (Ω / sq.) Of the TiN film after being left to stand was measured. For comparison, were measured sheet resistance also when after TiN film formation is not performed the supply of the SiH ₄ gas. Here, _{the supply time and flow rate of SiH 4} gas are set to 0.05 sec and 50 sccm, respectively, the temperature of the Si-containing gas supply step is 450 to 700 ° C, and the pressure is 266.6 to 1199.9 Pa (2 to 2). The range was 9 Torr). The sheet resistance and its uniformity at that time are shown in FIG.

As shown in FIG. 12, when the Si-containing gas supply step is not performed, the average value of the sheet resistance is 44.4 Ω / sq. The uniformity was 3.9%, whereas the average value of sheet resistance was 39.1 Ω / sq. When the number of times (cycle) of _{SiH 4 gas supply was 1 (1 cycle).} When the uniformity is 1.2% and the _{number of times (cycle) of SiH 4} gas is supplied is 5 (5 cycles), the average value of sheet resistance is 38.9Ω / sq. , The uniformity was 1.0%. That improves the resistivity and its uniformity by performing the supply of SiH ₄ gas, by further supply multiple times the SiH ₄ gas, the specific resistance and the uniformity is further improved.

Next, as a Si-containing gas supply step, when SiH ₄ gas and NH ₃ gas are supplied once (1 cycle), SiH ₄ gas and NH ₃ gas are alternately supplied 5 times (5 cycles) with a purge in between. In the case of supplying, the sheet resistance (Ω / sq.) Of the TiN film after being left in the air was measured. Here, _{the supply time and flow rate of SiH 4} gas were set to 0.05 sec and 50 sccm, respectively, and the supply time and flow rate of _{NH 3 gas were set to 0.05 sec and 600 sccm, respectively.} The temperature of the Si-containing gas supply step 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. FIG. 13 also shows the results when the Si-containing gas supply step of FIG. 12 is not performed.

As shown in FIG. 13, the average value of the sheet resistance when the Si-containing gas supply step is not performed is 44.4 Ω / sq. , To homogeneity 3.9%, the average 39.7Ω / sq sheet resistance of once the supply number of SiH ₄ gas and NH ₃ gas. When the uniformity is 1.2% and the _{number of times of supplying SiH 4} gas and NH ₃ gas is 5, the average value of the sheet resistance is 39.1 Ω / sq. , The uniformity was 1.2%. That improves sheet resistance and uniformity by performing the supply of SiH ₄ gas and NH ₃ gas, by supplying further SiH ₄ gas and NH ₃ gas a plurality of times, the sheet resistance was further improved.

After supplying the Si-containing gas 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, a film forming process of the next step is performed by another film forming apparatus. For example, a SiGe film 305 is formed. Then, after the necessary post-processing is performed, a desired semiconductor device (semiconductor device) is obtained. At this time, since the surface layer 304 containing Si is formed on the surface of the TiN film 303 by supplying the Si-containing gas, the oxidation of the TiN film 303 is suppressed and the specific resistance is maintained low. Therefore, good device characteristics can be obtained.

Since the film formed in the next step is the SiGe film 305, which is a Si-containing layer, it has a high affinity for the Si-containing surface layer 304 formed for suppressing oxidation. Further, since the SiGe film in the next step is formed on the surface layer 304 containing Si in this way, the incubation time is shortened when the SiGe film is formed by a general CVD method. The effect of can be obtained.

<Other applications>
Although the embodiments have been described above, the embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The above embodiments may be omitted, replaced or modified in various forms without departing from the scope of the appended claims and their gist.

For example, in the above embodiment, the case where the TiN film is formed as the metal film by the ALD method has been mainly described, but as described above, the metal film and the metal compound film whose characteristics may be deteriorated by oxidation. If so, it can be applied, and the film forming method is not limited to the ALD method.

Further, as the film forming apparatus of FIG. 3, the one for ALD film forming of the TiN film is exemplified, but the film forming apparatus of FIG. 3 can also be applied to the film forming of other metal-based films. Further, the film forming apparatus shown in FIG. 3 is merely an example, and if the film forming process and the Si-containing gas can be supplied into the processing container (chamber), a CVD film forming apparatus, a PVD film forming apparatus, etc. can be used. Any film forming apparatus may be used. Further, although the film forming apparatus of FIG. 3 is a single-wafer type apparatus, it may be a batch type film forming apparatus for forming a film on a plurality of substrates at once, such as a vertical type apparatus. Further, it may be a semi-batch type film forming apparatus in which a plurality of substrates are arranged on a stage to perform a film forming process.

Further, in the above embodiment, the semiconductor wafer has been described as an example of the substrate, but the substrate is not limited to the semiconductor wafer, and may be a glass substrate used for an FPD (flat panel display) or another substrate such as a ceramic substrate.

1; Chamber 2; Suceptor 3; Shower head 4; Exhaust unit 5; Gas supply mechanism 6; Control unit 51; TiCl ₄ gas supply source 52; NH ₃ gas supply source 53; DCS gas supply source 54, 55, 56; N ₂ Gas supply source 100; film forming apparatus 201; substrate 202; metal-based film 203; surface layer 301; Si substrate 302; SiO ₂ film 303; TiN film 304; surface layer W; semiconductor wafer (substrate)

Claims (25)

The process of installing the substrate in the processing container and
A step of forming a metal-based film on the substrate in the processing container, and
After that, a step of supplying the Si-containing gas into the processing container with the substrate provided in the processing container, and a step of supplying the Si-containing gas into the processing container.
A film forming method including. The step of supplying the Si-containing gas according to claim 1, wherein the supplied Si-containing gas is adsorbed on the surface of the metal-based film to form a Si-containing surface layer on the surface of the metal-based film. Film formation method. The film forming method according to claim 1 or 2, wherein the substrate temperature is in the range of 400 to 600 ° C. in the step of supplying the Si-containing gas. The film forming method according to any one of claims 1 to 3, wherein the Si-containing gas is at least one of a silane compound, a chlorosilane compound, and an organic silane compound. The film forming method according to claim 4, wherein the Si-containing gas is at least one of dichlorosilane, silane, and disilane. The film forming method according to any one of claims 1 to 5, wherein the step of supplying the Si-containing gas is a step of supplying the Si-containing gas a plurality of times. The film forming method according to any one of claims 1 to 5, 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 film forming method according to claim 7, wherein the step of supplying the Si-containing gas is a step of 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 8, wherein the step of forming the metal film is performed by any one of the ALD method, the CVD method, and the PVD method. Any of claims 1 to 9, wherein the metal-based film is any one of Ti film, TiN film, Ta film, TaN film, W film, Al film, Mo film, Ru film, Co film, and Ni film. The film forming method according to item 1. The film forming method according to claim 1, wherein the metal film is a TiN film, and the step of forming the metal film is performed by the ALD method. In the step of supplying the Si-containing gas, the supplied Si-containing gas is adsorbed on the surface of the metal-based film to form a Si-containing surface layer on the surface of the metal-based film, and the surface layer contains TiSiN. The film forming method according to claim 11, which includes. The film forming method according to claim 8 or 9, wherein the Si-containing gas is dichlorosilane. The film forming method according to any one of claims 11 to 13, wherein the step of supplying the Si-containing gas is a step of supplying the Si-containing gas a plurality of times. The film formation of the TiN film is _{performed using a Ti-containing gas and an NH 3} gas, and the step of supplying the Si-containing gas is a step of supplying the Si-containing gas and the NH ₃ gas, claims 11 to 11. The film forming method according to any one of 14. Step of supplying the Si-containing gas, the Si-containing gas and the NH ₃ supplying a plurality of times and gas alternately, the film forming method according to claim 15. The film forming method according to any one of claims 11 to 16, wherein the substrate is a semiconductor substrate on which a patterned SiO _{2 film is formed.} The processing container that houses the substrate and
A gas supply mechanism for supplying a gas for forming a metal-based film and a Si-containing gas in the processing container,
An exhaust mechanism that exhausts the inside of the processing container and
A heating mechanism for heating the substrate and
Control unit and
Have,
The control unit
The process of providing the substrate in the processing container and
A step of forming the metal-based film on the substrate in the processing container, and
After that, a step of supplying the Si-containing gas into the processing container and
A film forming apparatus that controls the execution of. The process of providing the substrate in the processing container of the first film forming apparatus and
A step of forming a metal-based film on the substrate in the processing container, and
After that, a step of supplying the Si-containing gas into the processing container with the substrate provided in the processing container, and a step of supplying the Si-containing gas into the processing container.
A step of carrying out the substrate from the processing container and forming a Si-containing film on the substrate by a second film forming apparatus.
A method for manufacturing a semiconductor device. The method for manufacturing a semiconductor device according to claim 19, wherein the step of supplying the Si-containing gas is a step of supplying the Si-containing gas a plurality of times. The method for manufacturing a semiconductor device according to claim 19, 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 21, wherein the step of supplying the Si-containing gas is a step of alternately supplying the Si-containing gas and the reaction gas a plurality of times. In the step of supplying the Si-containing gas, the supplied Si-containing gas is adsorbed on the surface of the metal-based film to form a Si-containing surface layer on the surface of the metal-based film. The method for manufacturing a semiconductor device according to any one of claims 19 to 22, which is formed on the surface of the surface layer. The method for manufacturing a semiconductor device according to claim 23, wherein the metal-based film is a TiN film and the Si-containing film is a SiGe film. The method for manufacturing a semiconductor device according to claim 24, wherein the substrate is a semiconductor substrate on which a patterned SiO _{2 film is formed.}

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