JP2004197219A - Film deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition method where, at the time when a TiN film is deposited, and a TiN film is thereafter deposited thereon, film peeling or the like do not occur therebetween even if the TiN film is the one deposited at a low temperature. <P>SOLUTION: The substrate W to be treated is mounted on a mounting stand 52 at the inside of a treatment chamber 51, Ti compound gas and reducing gas are charged from a gas discharge member 60 provided so as to be confronted with the mounting stand 52, and further, plasma is generated inside the treatment chamber 51 to deposit a Ti film on the substrate to be treated by plasma CVD (Chemical Vapor Deposition). In this case, the gas discharge member 60 is heated by a heater 96, and the mounting stand 52 is heated by a heater 55, i.e., they are independently heatable, respectively. The mounting stand 52 is heated by the heater 55 to control the temperature of the substrate W to be treated at 300 to 700°C, and the gas discharge member 60 is heated by the heater 96 to control the temperature thereof at ≥450°C. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a deposition method including deposition of a thin film by plasma CVD.

  In the manufacture of semiconductor devices, in response to recent demands for higher density and higher integration, the circuit configuration tends to have a multilayer wiring structure. For this reason, the connection between the lower semiconductor substrate and the upper wiring layer is required. An embedding technique for electrical connection between layers such as a contact hole as a part and a via hole as a connection part between upper and lower wiring layers is important.

  In general, Al (aluminum), W (tungsten), or an alloy mainly composed of these is used for filling such a contact hole or via hole. Such a metal or alloy and an underlying Si substrate or poly are used. In order to form a contact with the -Si layer, a Ti film is formed inside a contact hole or a via hole before the filling, and a TiN film is further formed as a barrier layer.

  Such Ti films and TiN films have been conventionally formed using physical vapor deposition (PVD). However, recently, miniaturization and high integration of devices are particularly required, and design rules are particularly important. As the line becomes tighter and the line width and hole opening diameter become smaller and the aspect ratio becomes higher, the PVD film has increased electrical resistance, making it difficult to meet the requirements.

Therefore, the Ti film and the TiN film are formed by chemical vapor deposition (CVD) which can be expected to form a higher quality film. In forming these films, TiCl ₄ (titanium tetrachloride) is used as a film forming gas, and TiCl ₄ and H ₂ (hydrogen) are reacted while a semiconductor wafer as a substrate is heated by a stage heater. A Ti film is formed, and TiN film is formed by reacting TiCl ₄ and NH ₃ (ammonia).

As a problem of such CVD film formation using TiCl ₄ , chlorine remains in the film and the specific resistance of the film increases. In particular, recently, film formation at a low temperature is directed, and in this case, the chlorine concentration in the film is higher.

In order to deal with such a problem of residual chlorine, Patent Document 1 discloses that when forming a TiN film, (1) supplying TiCl ₄ gas, (2) stopping TiCl ₄ gas, supplying purge gas, and supplying TiCl ₄ A technique is disclosed that repeats the steps of removing gas, (3) stopping purge gas and supplying NH ₃ gas, and (4) stopping NH ₃ gas and supplying purge gas to remove NH ₃ . According to this technique, residual chlorine can be reduced and film formation at a lower temperature is possible.

On the other hand, in the case of a Ti film, since it is formed by plasma CVD, it is difficult to maintain a plasma that maintains an appropriate matching state for transmission impedance when such alternate gas switching is performed. It is considered that there is no such method for forming the Ti film, and the film is formed at a relatively high temperature of 600 ° C. or higher under the condition that TiCl ₄ and H ₂ are simultaneously flowed. The problem is solved.

  Recently, silicides such as CoSi and NiSi having better contact characteristics are being used instead of poly-Si from the viewpoint of speeding up the device. Among these, NiSi is attracting attention as a logic contact.

  However, NiSi has low heat resistance, and when a Ti film is formed thereon by CVD, the film forming temperature needs to be as low as about 450 ° C. At such a low temperature, the film is formed by a conventional method. However, even if a film can be formed, the residual chlorine concentration is high and the film quality is poor. In addition, when the Ti film is formed, a Ti film is also formed in advance on the shower head which is a gas discharge member, but in the case of low temperature film formation, the heating temperature of the susceptor on which the wafer is placed is low. The temperature of the shower head for gas discharge provided facing the susceptor is also lowered, and a stable Ti film cannot be formed on the shower head. For this reason, the Ti film is peeled off, which also deteriorates the film quality of the Ti film.

Further, when a Ti film is formed at a low temperature of 450 ° C. by a conventional method and then a TiN film is formed thereon, film peeling occurs between these films.
JP 11-172438 A

  The present invention has been made in view of such circumstances, and can form a film at a low temperature in a film formed by plasma CVD typified by a Ti film. An object of the present invention is to provide a film forming method capable of reducing residues in the film.

  In addition, the present invention provides a film forming method in which, when a TiN film is formed on a Ti film after the Ti film is formed, even if the Ti film is formed at a low temperature, no film peeling occurs between them. The purpose is to do.

  In order to solve the above problems, according to a first aspect of the present invention, a step of removing a natural oxide film on the surface of a substrate to be processed in a first processing chamber by plasma, and then a step in a second processing chamber. Forming a Ti film on the processing substrate by CVD, and forming the Ti film includes a first step of generating a first plasma while introducing a Ti compound gas and a reducing gas; There is provided a film forming method characterized by alternately repeating a second step of generating a second plasma while stopping a compound gas and introducing the reducing gas. In this case, after the first step and the second step are repeated a plurality of times, a nitriding treatment is performed by generating a third plasma while introducing the reducing gas and a gas containing N and H. preferable.

  In the second aspect of the present invention, the substrate to be processed is mounted on the mounting table in the processing chamber, and the Ti compound gas and the reducing gas are discharged from the gas discharge member provided facing the mounting table. A film forming method in which a Ti film is formed by plasma CVD on a substrate to be processed by generating plasma in a processing chamber, wherein the mounting table and the gas discharge member can be heated independently from each other. There is provided a film forming method characterized in that a stage is heated to control a temperature of a substrate to be processed to 300 to 700 ° C., and the gas discharge member is heated to control the temperature to 450 ° C. or higher. In this case, it is preferable to control the temperature of the substrate to be processed to a low temperature of 300 ° C. or higher and lower than 550 ° C. by heating the mounting table.

  In addition, a compound gas containing a component of a film to be formed on the substrate to be formed in the processing chamber and a reducing gas are supplied, and plasma is generated in the chamber to form a thin film on the substrate to be processed by CVD. A film forming method, wherein a first step of generating a first plasma while introducing the compound gas and a reducing gas and a second step of generating a second plasma while introducing the reducing gas are alternately performed It is also possible to provide a film forming method characterized by being repeated a plurality of times.

  As described above, the first step of generating the first plasma while introducing the compound gas and the reducing gas and the second step of generating the second plasma while introducing the reducing gas are preferably performed a plurality of times alternately. By repeating 3 times or more, effective reduction can be performed, film formation at a lower temperature becomes possible, and residues in the film can be reduced, so that a film with better film quality is formed. can do.

  In this case, the second step may be performed by introducing a nitriding gas in addition to the reducing gas. Further, after the first step and the second step are repeated a plurality of times, a nitriding treatment may be performed by generating a third plasma while introducing the reducing gas and the nitriding gas.

  Furthermore, a film forming method for forming a Ti or Ti / TiN film on a substrate to be processed in a processing chamber by a first step of generating a first plasma while introducing a Ti compound gas and a reducing gas; And a second step of alternately repeating the second step of generating the second plasma while stopping the Ti compound gas and introducing the reducing gas and the gas containing N and H are provided. You can also

  As described above, the first step of generating the first plasma while introducing the Ti compound gas and the reducing gas, and the second step while stopping the Ti compound gas and introducing the reducing gas and the gas containing N and H are performed. By repeating the second step of generating plasma alternately several times, the Ti compound can be effectively reduced, and the Ti film can be effectively nitrided to prevent the Ti film from deteriorating. Therefore, it is possible to form a film even when the temperature of the substrate to be processed at the time of film formation is as low as 450 ° C. or less, and it is possible to reduce residues such as chlorine even at such a low temperature film formation. And a high-quality Ti film having a low specific resistance can be obtained. Further, it can be used as a Ti film or a Ti / TiN film by controlling the amount and supply time of a gas containing N and H.

  Furthermore, a film forming method for forming a Ti / TiN film on a substrate to be processed in a processing chamber by CVD, wherein a first step of generating a first plasma while introducing a Ti compound gas and a reducing gas; A Ti film is formed by alternately repeating the second step of generating the second plasma while stopping the Ti compound gas and introducing the reducing gas, and the third step while introducing the Ti compound gas and the reducing gas. By alternately repeating the third step of generating the plasma of step 4 and the fourth step of generating the fourth plasma while stopping the Ti compound gas and introducing the reducing gas and the gas containing N and H. It is also possible to provide a film forming method characterized by forming a TiN film.

  As described above, the first step of generating the first plasma while introducing the Ti compound gas and the reducing gas, and the second step of generating the second plasma while stopping the Ti compound gas and introducing the reducing gas, Are alternately repeated a plurality of times, preferably three times or more, to form a Ti film and introduce a Ti compound gas and a reducing gas to generate a third plasma, and the Ti compound gas is stopped and the reduction is performed. Since the TiN film is formed by repeating the fourth step of generating the fourth plasma while introducing the gas and the gas containing N and H alternately several times, preferably three times or more, the Ti film is formed. In both cases, the Ti compound gas can be effectively reduced both during the formation of the TiN film. Therefore, it is possible to form a film sufficiently even when the temperature of the substrate to be processed is as low as 450 ° C. or less, and it is possible to reduce residues such as chlorine even in such a low temperature film formation. In addition, a Ti film and a TiN film having a low specific resistance and good quality can be obtained. In addition, since a Ti / TiN laminated structure, which conventionally required two kinds of film forming apparatuses, can be continuously formed with one kind of film forming apparatus, it is extremely efficient. In order to reliably form the TiN film, it is preferable to set the time of the fourth step to be longer than the time of the third step.

TiCl ₄ gas is used as the Ti compound gas, H ₂ gas is used as the reducing gas, and a rare gas such as Ar, He, or Xe can be introduced in all steps. Furthermore, NH ₃ gas can be used as the gas containing N and H.

  Furthermore, there is provided a film forming method for forming a Ti / TiN film on a substrate to be processed, wherein the substrate to be processed is set in a first processing chamber and a first plasma is introduced while introducing a Ti compound gas and a reducing gas. A second step of forming a Ti film by alternately repeating a first step of generating a second step of generating a second plasma while stopping the Ti compound gas and introducing the reducing gas. There is provided a film forming method characterized in that an object to be processed on which a Ti film is formed is set and a TiN film is formed on the Ti film using a Ti compound gas and a gas containing N and H. You can also

  As described above, the first step of generating the first plasma while introducing the Ti compound gas and the reducing gas, and the second step of generating the second plasma while stopping the Ti compound gas and introducing the reducing gas, By alternately forming the TiN film on the Ti film formed by alternately repeating a plurality of times, preferably three times or more, using a gas containing Ti compound gas and N and H, the second aspect of the present invention is achieved. In addition to the effect of the configuration, it is possible to obtain an effect that film peeling between the Ti film and the TiN film can be made difficult to occur. In this case, after the first step and the second step are repeated a plurality of times, a nitriding treatment is performed by generating a third plasma while introducing the reducing gas and a gas containing N and H. preferable.

  Furthermore, in the film forming method for forming a Ti / TiN film on the substrate to be processed by CVD, the substrate to be processed is set in the first processing chamber, and the first gas is introduced while introducing the Ti compound gas and the reducing gas. The first step of generating the plasma and the second step of generating the second plasma while stopping the Ti compound gas and introducing the reducing gas and the gas containing N and H are alternately repeated several times. Forming a film, setting a target object on which a Ti film is formed in a second processing chamber, and forming a TiN film on the Ti film using a gas containing Ti compound gas and N and H The film-forming method characterized by these can also be provided.

  As described above, the first step of generating the first plasma while introducing the Ti compound gas and the reducing gas, and the second step while stopping the Ti compound gas and introducing the reducing gas and the gas containing N and H are performed. On the Ti film formed by alternately repeating the second step of generating plasma a plurality of times, preferably three times or more, by using a gas containing Ti compound gas and N and H, In addition to the effect of the configuration of the third aspect, it is possible to obtain an effect that it is difficult to cause film peeling between the Ti film and the TiN film.

The TiN film is formed by a first step of forming a film by introducing a Ti compound gas and a gas containing N and H, and a second step of stopping the Ti compound gas and introducing a gas containing N and H. Are preferably carried out by alternately repeating a plurality of times. Thereby, the TiN film can be formed at a lower temperature, and the film quality of the TiN film can be improved. In this case, it is preferable to have a third step of introducing a purge gas such as N ₂ gas between the first step and the second step. Further, TiCl ₄ gas can be used as the Ti compound gas, H ₂ gas can be used as the reducing gas, and NH ₃ gas can be used as the gas containing N and H. It is preferable to introduce H ₂ when forming the Ti film and / or TiN film. Furthermore, it is preferable that the Ti film and the TiN film are formed continuously without breaking the vacuum.

  The temperature of the substrate to be processed can be set to 300 to 700 ° C. during processing while the substrate to be processed is mounted on the mounting table. Further, prior to the formation of the Ti film, it is preferable to remove the natural oxide film on the underlying surface.

  The plasma is preferably generated by supplying high-frequency power to at least one of the pair of parallel plate electrodes, and the plasma impedance and the transmission line impedance are preferably matched by an electronic matching network. Such an electronic matching type matching network can follow a change in plasma state in a short time, and therefore can sufficiently cope with such alternate gas switching.

  As a processing apparatus for realizing such a method, a processing chamber for storing a substrate to be processed, a mounting table for mounting the substrate to be processed in the processing chamber, and a component of a film to be formed in the processing chamber A gas supply means for supplying a compound gas containing a reducing gas, a pair of electrodes for generating plasma in the processing chamber, a high-frequency power source for supplying high-frequency power to at least one of the pair of electrodes, and plasma An electronic matching network that matches impedance to transmission line impedance, a valve group that switches on / off of the compound gas and the reducing gas, and the valve group that controls the compound gas and the reducing gas The first step for introducing the reducing gas and the second step for introducing the reducing gas are alternately repeated a plurality of times. Those and control means for the like.

  Thus, a high frequency power source that supplies high frequency power to at least one of the pair of electrodes and a valve group that switches on / off of the compound gas and the reducing gas are provided, and the valve group is controlled by the control means, and the compound is controlled. Matching that matches the plasma impedance to the transmission line impedance when the film is formed by plasma CVD by controlling the first step for introducing the gas and the reducing gas and the second step for introducing the reducing gas alternately alternately several times. Since an electronic matching network is used, it is possible to follow a change in plasma state in a short time, and to achieve an optimum plasma state in a short time against such alternate gas switching. Can do.

  According to the first aspect of the present invention, the first plasma is generated while introducing the Ti compound gas and the reducing gas when the Ti film is formed after the surface of the substrate to be processed is cleaned with plasma. The Ti compound is effectively reduced by repeating the step and the second step of generating the second plasma while stopping the Ti compound gas and introducing the reducing gas a plurality of times, preferably three times or more. Therefore, it is possible to form a Ti film even if the temperature of the substrate to be processed at the time of film formation is as low as about 450 ° C., and even if the film is formed at a low temperature, residues such as chlorine can be removed. Therefore, it is possible to obtain a Ti film having a low specific resistance and a good quality.

According to the second aspect of the present invention, “in the Ti film formation, the temperature of the Ti compound gas such as TiCl ₄ gas discharged from the gas discharge member is effectively reduced by setting the temperature to 450 ° C. or higher. Although a reaction can occur, conventionally, when a low temperature film formation of less than 550 ° C. is attempted in accordance with a request for a base film or the like, the temperature of the gas discharge member, that is, the shower head does not rise to 450 ° C. The mounting table and the gas discharge member can be heated independently of each other against the problem that the film of the Ti film formed on the head may be peeled off and the film quality of the Ti film may be deteriorated. Since the discharge member is heated and its temperature is always controlled to 450 ° C. or higher, film peeling of the gas discharge member can be prevented regardless of the temperature of the substrate to be processed. This is particularly effective when the temperature of the substrate to be processed is controlled to a low temperature of 300 ° C. or higher and lower than 550 ° C. by heating the mounting table.

Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram showing a multi-chamber type film forming system equipped with a Ti film forming apparatus for carrying out an embodiment of the film forming method of the present invention.

  As shown in FIG. 1, this film forming system 100 has a wafer transfer chamber 1 having a hexagonal shape, and connection ports 1a, 1b, and 1c to which predetermined processing apparatuses are respectively connected on four sides thereof. , 1d, and a connection port 1a is connected to a pre-cleaning device 2 for removing a natural oxide film on a film formation base of a semiconductor wafer W which is a substrate to be processed, and the connection port 1b is formed of a Ti film by plasma CVD. A Ti film forming apparatus 3 for forming TiN is connected, and a TiN film forming apparatus 4 for forming TiN by thermal CVD is connected to the connection port 1c. Although no processing device is connected to the connection port 1d, an appropriate processing device 5 can be connected as necessary. Load lock chambers 6 and 7 are provided on the other two sides of the wafer transfer chamber 1, respectively. A wafer carry-in / out chamber 8 is provided on the opposite side of the load-lock chambers 6 and 7 from the wafer transfer chamber 1, and a wafer W can be accommodated on the opposite side of the load-lock chambers 6 and 7 from the load-lock chambers 6 and 7. Ports 9, 10, and 11 for attaching three FOUPs F are provided.

  The pre-cleaning device 2, the Ti film forming device 3, the TiN film forming device 4 and the load lock chambers 6 and 7 are connected via a gate valve G as shown in FIG. By opening, it communicates with the wafer transfer chamber 1, and by closing each gate valve G, it is cut off from the wafer transfer chamber 1. A gate valve G is also provided at a portion of the load lock chambers 6 and 7 connected to the wafer loading / unloading chamber 8. The load lock chambers 6 and 7 open the gate loading / unloading chamber 8 by opening the gate valve G. 8, and is closed from the wafer loading / unloading chamber 8 by closing them.

  Into the wafer transfer chamber 1, the wafer W as the object to be processed is carried into and out of the pre-cleaning device 2, the Ti film forming device 3, the TiN film forming device 4, and the load lock chambers 6 and 7. A wafer transfer device 12 is provided. The wafer transfer device 12 is disposed substantially at the center of the wafer transfer chamber 1 and has two blades 14 a and 14 b that hold the wafer W at the tip of a rotatable / extensible / retractable portion 13 that can be rotated and extended. These two blades 14a and 14b are attached to the rotating / extending / contracting portion 13 so as to face opposite directions. The wafer transfer chamber 1 is maintained at a predetermined degree of vacuum.

  A HEPA filter (not shown) is provided in the ceiling portion of the wafer carry-in / out chamber 8, and clean air that has passed through the HEPA filter is supplied into the wafer carry-in / out chamber 8 in a down-flow state. The wafer W is loaded and unloaded in a clean air atmosphere. Shutters (not shown) are provided in the three ports 9, 10, 11 for attaching the FOUP F of the wafer carry-in / out chamber 8, and the wafers W are accommodated in these ports 9, 10, 11 or empty. The hoop is directly attached, and when it is attached, the shutter is released to communicate with the wafer carry-in / out chamber 8 while preventing the entry of outside air. An alignment chamber 15 is provided on the side surface of the wafer carry-in / out chamber 8 where the wafer W is aligned.

  In the wafer loading / unloading chamber 8, a wafer transfer device 16 for loading / unloading the wafer W into / from the FOUP F and loading / unloading the wafer W into / from the load lock chambers 6, 7 is provided. The wafer transfer device 16 has an articulated arm structure and can run on the rail 18 along the direction in which the hoops F are arranged, and the wafer W is placed on the hand 17 at the tip thereof and transferred. I do.

  Control of the entire system, such as operations of the wafer transfer devices 12 and 16, is performed by the control unit 19.

  In such a film forming system 100, first, one wafer W is taken out from one of the FOUPs F by the wafer transfer device 16 in the wafer carry-in / out chamber 8 held in a clean air atmosphere at atmospheric pressure, and the alignment chamber. Then, the wafer W is aligned. Next, the wafer W is carried into one of the load lock chambers 6 and 7, and the load lock chamber is evacuated, and then the wafer in the load lock chamber is taken out by the wafer transfer device 12 in the wafer transfer chamber 1. Is loaded into the pre-cleaning apparatus 2 to remove the natural oxide film on the underlying surface, and then the wafer W is loaded into the Ti film forming apparatus 3 to form a Ti film. Is continuously inserted into the TiN film forming apparatus 4 to form a TiN film. That is, in this film forming system 100, the natural oxide film removal, Ti film formation, and TiN film formation are performed in situ without breaking the vacuum. Thereafter, the wafer W after film formation is loaded into one of the load lock chambers 6 and 7 by the wafer transfer device 12 and returned to atmospheric pressure, and then the load lock is performed by the wafer transfer device 16 in the wafer carry-in / out chamber 8. The wafer W in the room is taken out and accommodated in one of the FOUPs F. Such an operation is performed on one lot of wafers W, and the processing for one lot is completed.

  With such a film formation process, for example, as shown in FIG. 2, a Ti film 23 as a contact layer and a barrier layer are formed in the via hole 22 formed in the interlayer insulating film 21 and reaching the underlying conductive layer 20. A TiN film 24 is formed. Thereafter, film formation of Al, W, or the like is performed by another apparatus, and the contact hole 22 is buried and a wiring layer is formed. Examples of the conductive layer 20 include silicide such as poly-Si, CoSi, and NiSi.

Next, the pre-cleaning device 2 will be described.
The pre-cleaning apparatus 2 is an inductively coupled plasma (ICP) system, and is used to remove a poly-Si or silicide natural oxide film as a base, and has a substantially cylindrical shape as shown in FIG. , And a substantially cylindrical bell jar 32 provided continuously above the chamber 31. A susceptor 33 made of ceramics such as AlN for horizontally supporting a wafer W as an object to be processed is disposed in the chamber 31 while being supported by a cylindrical support member 34. A clamp ring 35 that clamps the wafer W is provided on the outer edge of the susceptor 33. In addition, a heater 36 for heating the wafer W is embedded in the susceptor 33. The heater 36 is supplied with power from a heater power supply 39 to heat the wafer W, which is an object to be processed, to a predetermined temperature.

  The bell jar 32 is formed of an electrically insulating material such as quartz or a ceramic material, and a coil 37 as an antenna member is wound around the bell jar 32. A high frequency power supply 38 is connected to the coil 37. The high frequency power supply 38 has a frequency of 300 kHz to 60 MHz, preferably 450 kHz. An induction electromagnetic field is formed in the bell jar 32 by supplying high frequency power from the high frequency power supply 38 to the coil 37.

  The gas supply mechanism 40 is for introducing a processing gas into the chamber 31, and includes a gas supply source of a predetermined gas, piping from each gas supply source, an open / close valve, and a mass flow controller ( Neither is shown). A gas introduction nozzle 42 is provided on the side wall of the chamber 31, a pipe 41 extending from the gas supply mechanism 40 is connected to the gas introduction nozzle 42, and a predetermined gas passes through the gas introduction nozzle 42. Introduced in. Note that the valves and the mass flow controller of each pipe are controlled by a controller (not shown).

Examples of the processing gas include Ar, Ne, and He, which can be used alone. Further, Ar, Ne, combined with any of He and _{H 2,} and Ar, Ne, may be combined with any and NF ₃ in He. Among these, Ar alone and Ar + H ₂ are preferable.

  An exhaust pipe 43 is connected to the bottom wall of the chamber 31, and an exhaust device 44 including a vacuum pump is connected to the exhaust pipe 43. Then, by operating the exhaust device 44, the chamber 31 and the bell jar 32 can be depressurized to a predetermined degree of vacuum.

  A gate valve G is provided on the side wall of the chamber 31 and is connected to the wafer transfer chamber 1 through the gate valve G as described above.

  Further, in the susceptor 33, for example, an electrode 45 formed by weaving molybdenum wire or the like in a mesh shape is embedded, and a high-frequency power source 46 is connected to the electrode 45 so that a bias is applied.

In the pre-cleaning apparatus 2 configured as described above, the gate valve G is opened, the wafer W is loaded into the chamber 31, the wafer W is placed on the susceptor 33, and clamped by the clamp ring 35. Thereafter, the gate valve G is closed, the exhaust device 44 exhausts the chamber 31 and the bell jar 32 to a predetermined reduced pressure state, and subsequently, a predetermined gas is introduced into the chamber 31 from the gas supply mechanism 40 through the gas introduction nozzle 42. For example, inductively coupled plasma is generated by supplying high frequency power from the high frequency power supply 38 to the coil 37 while introducing Ar gas or Ar gas and H ₂ gas to form an induction electromagnetic field in the bell jar 32. On the other hand, high frequency power is supplied from the high frequency power supply 46 to the susceptor 33, and ions are drawn into the wafer W.

  In this way, the inductively coupled plasma is applied to the wafer W to remove the natural oxide film formed on the surface of the underlying conductive layer. In this case, since the inductively coupled plasma has a high density, the natural oxide film can be efficiently removed without damaging the base with low energy.

Next, the Ti film forming apparatus 3 will be described.
FIG. 4 is a cross-sectional view showing the Ti film forming apparatus 3. This Ti film forming apparatus 3 has a substantially cylindrical chamber 51 that is airtightly configured, and a susceptor 52 for horizontally supporting a wafer W that is an object to be processed is placed in the lower center of the chamber 51. It arrange | positions in the state supported by the cylindrical support member 53 provided in this. The susceptor 52 is made of ceramics such as AlN, and a guide ring 54 for guiding the wafer W is provided on the outer edge thereof. In addition, a heater 55 is embedded in the susceptor 52, and the heater 55 is heated by a heater power source 56 to heat the wafer W as a substrate to be processed to a predetermined temperature. In the susceptor 52, an electrode 58 that functions as a lower electrode is embedded on the heater 55.

  A shower head 60 is provided on the top wall 51 a of the chamber 51 via an insulating member 59. The shower head 60 includes an upper block body 60a, a middle block body 60b, and a lower block body 60c. A ring-shaped heater 96 is embedded in the vicinity of the outer periphery of the lower block body 60c, and the heater 96 can be heated to a predetermined temperature by being supplied with power from a heater power source 97. ing.

  Discharge holes 67 and 68 for discharging gas are alternately formed in the lower block body 60c. A first gas inlet 61 and a second gas inlet 62 are formed on the upper surface of the upper block body 60a. In the upper block body 60 a, a large number of gas passages 63 are branched from the first gas inlet 61. Gas passages 65 are formed in the middle block body 60b, and the gas passages 63 communicate with these gas passages 65 through communication passages 63a extending horizontally. Further, the gas passage 65 communicates with the discharge hole 67 of the lower block body 60c. In the upper block body 60a, a large number of gas passages 64 are branched from the second gas introduction port 62. Gas passages 66 are formed in the middle block body 60 b, and the gas passages 64 communicate with these gas passages 66. Further, the gas passage 66 is connected to a communication passage 66a extending horizontally into the middle block body 60b, and the communication passage 66a communicates with a number of discharge holes 68 of the lower block body 60c. The first and second gas introduction ports 61 and 62 are connected to gas lines 78 and 80 of a gas supply mechanism 70 described later, respectively.

The gas supply mechanism 70 includes a ClF ₃ gas supply source 71 that supplies a ClF ₃ gas that is a cleaning gas, a TiCl ₄ gas supply source 72 that supplies a TiCl ₄ gas that is a Ti-containing gas, and a first Ar that supplies Ar gas. gas supply source 73, a reducing gas at a _{H 2} gas _{H 2} gas supply source 74 for supplying, NH ₃ gas for supplying the NH ₃ gas supply source 75, a second Ar gas supply for supplying an Ar gas as a nitriding gas A source 76 is provided. The ClF ₃ gas supply source 71 has a ClF ₃ gas supply line 77, the TiCl ₄ gas supply source 72 has a TiCl ₄ gas supply line 78, and the first Ar gas supply source 73 has a first Ar gas supply. line 79, the _{H 2} gas line 80 for _{H 2} gas supply source 74 is, NH ₃ NH ₃ gas supply line 80a to the gas supply source 75 is, in the second Ar gas supply source 76 second Ar gas Supply lines 80b are connected to each other. Although not shown, also has N ₂ gas supply source. Each gas supply line is provided with two valves 81 sandwiching the mass flow controller 82 and the mass flow controller 82.

A TiCl ₄ gas supply line 78 extending from a TiCl ₄ gas supply source 72 is connected to the first gas inlet 61, and a ClF ₃ gas extending from a ClF ₃ gas supply source 71 is connected to the TiCl ₄ gas supply line 78. A first Ar gas supply line 79 extending from the supply line 77 and the first Ar gas supply source 73 is connected. Further, an H ₂ gas supply line 80 extending from an H ₂ gas supply source 74 is connected to the second gas introduction port 62, and this H ₂ gas supply line 80 extends from an NH ₃ gas supply source 75. An NH ₃ gas supply line 80 a and a second Ar gas supply line 80 b extending from the second Ar gas supply source 76 are connected. Therefore, when the process, TiCl ₄ TiCl ₄ gas from the gas supply source 72 is first gas inlet of the shower head 60 through the TiCl ₄ gas supply line 78 together with Ar gas from the first Ar gas supply source 73 61 reaches the showerhead 60 from one discharged into the chamber 51 from the discharge hole 67 through the gas passage 63, 65, _{H 2} gas is the second Ar gas supply a reducing gas from the _{H 2} gas supply source 74 Together with Ar gas from the source 76, the second gas inlet 62 of the shower head 60 reaches the shower head 60 through the H ₂ gas supply gas line 80, passes through the gas passages 64 and 66, and is discharged from the discharge hole 68 into the chamber 51. Is discharged. That is, the shower head 60 is of a matrix type in which TiCl ₄ gas and H ₂ gas are supplied into the chamber 51 completely independently, and these are mixed and reacted after discharge. In the case of performing nitriding treatment, NH ₃ NH ₃ gas from the gas supply source 75 by flowing the H ₂ gas gas line 80 which is a reducing gas H ₂ gas and Ar gas at the same time, the second gas introduction It is introduced into the shower head 60 from the port 62 and discharged from the discharge port 68. Further, the valve 81 and the mass flow controller 82 are controlled by a controller 98 to perform alternate gas supply as described later.

  A transmission path 83 is connected to the shower head 60, and a high frequency power supply 84 is connected to the transmission path 83 via an electronic matching network 100, and transmission is performed from the high frequency power supply 84 during film formation. High frequency power is supplied to the shower head 60 via a path 83. By supplying high-frequency power from the high-frequency power supply 84, a high-frequency electric field is generated between the shower head 60 and the electrode 58, and the gas supplied into the chamber 51 is turned into plasma to form a Ti film. A controller 106 is connected to the transmission path 83. A reflected wave from the plasma is input to the controller 106 via the transmission path 83, and the electronic matching network 100 is controlled so that the reflected wave from the plasma is zero or minimized. As the high frequency power supply 84, one having a frequency of 400 kHz to 13.56 MHz is used.

  The electronic matching network 100 includes a capacitor 101 and two coils 102 and 104 as in the case of a normal matching network, but the two coils 102 and 104 electrically transmit magnetic fields from the induction coils 103 and 105, respectively. The reactance is made variable by changing to, and there is no mechanical moving part like a normal matching network. Accordingly, the plasma tracking is extremely fast, and the steady state can be obtained in about 0.5 sec, which is about 1/10 of the normal matching network. For this reason, it is suitable when performing alternate gas supply while forming plasma as described later.

  A circular hole 85 is formed in the center of the bottom wall 51b of the chamber 51, and an exhaust chamber 86 is provided on the bottom wall 51b so as to protrude downward so as to cover the hole 85. An exhaust pipe 87 is connected to the side surface of the exhaust chamber 86, and an exhaust device 88 is connected to the exhaust pipe 87. By operating the exhaust device 88, the inside of the chamber 51 can be depressurized to a predetermined degree of vacuum.

  The susceptor 52 is provided with three (two only shown) wafer support pins 89 for supporting the wafer W to be moved up and down so as to protrude and retract with respect to the surface of the susceptor 52. It is fixed to the plate 90. The wafer support pins 89 are lifted and lowered via a support plate 90 by a drive mechanism 91 such as an air cylinder.

  On the side wall of the chamber 51, a loading / unloading port 92 for loading / unloading the wafer W to / from the wafer transfer chamber 1 and a gate valve G for opening / closing the loading / unloading port 92 are provided.

Next, a Ti film forming method using such an apparatus will be described.
First, the chamber 51 is evacuated to a pressure of 667 Pa, the heater 55 heats the susceptor 52 to 350 to 700 ° C., and the heater 96 heats the shower head 60 to a temperature of 450 ° C. or higher, for example, about 470 to 490 ° C. To do.

In this state, TiCl ₄ gas and Ar gas are supplied from the TiCl ₄ gas supply source 72 and the first Ar gas supply source 73 to the first gas inlet 61 while applying high frequency power from the high frequency power supply 84 to the shower head 60. and, _{H 2} gas supply source 74, from the second Ar gas supply source 76 to the second gas inlet 62 supplies _{H 2} gas and Ar gas, respectively discharged from the gas discharge holes 67 and 68. As a result, plasma of these gases is formed in the chamber 51, and a Ti film is pre-coated on the inner wall of the chamber 51 and chamber inner members such as the shower head 60. At this time, the gas flow rates were as follows: TiCl ₄ gas: 0.01 to 0.02 L / min (10 to 20 sccm), H ₂ gas: 1.5 to 4.5 L / min (1500 to 4500 sccm), Ar gas: 0.0. It is about 8 to 2.0 L / min (800 to 2000 sccm). The power of the high frequency power supply 84 is about 500 to 1500 W.

  Then, with the temperatures of the susceptor 52 and the shower head 60 maintained as they are, the gate valve G is opened, and the wafer W is passed from the vacuum wafer transfer chamber 1 through the loading / unloading port 92 by the blade 14a or 14b of the transfer device 12. Is loaded into the chamber 51 and placed on the wafer support pins 89 protruding from the susceptor 52. The blade 14 a or 14 b is returned to the wafer transfer chamber 1, the gate valve G is closed, the wafer support pins 89 are lowered, and the wafer W is placed on the susceptor 52.

  In this state, Ti film formation on the wafer W is started. In this case, conventionally, there is no heater in the shower head 60, and the shower head 60 is indirectly heated by the susceptor 52, so that the Ti film pre-coated on the shower head 60 is secured at 450 ° C. or higher. Therefore, the temperature of the susceptor 52 needs to be about 550 ° C. or higher. Under these conditions, there was no problem in the case of film formation on Si or CoSi, but application to various applications has recently been studied and film formation at a lower temperature is desired. For example, when NiSi, which is attracting attention as a logic contact, is used as a base, the film forming temperature is limited to about 450 to 500 ° C., so that it has been difficult to apply under conventional CVD-Ti film forming conditions. Although application to a capacitor film, a low-k film, and further to an Al film is also conceivable, in this case as well, a film formation temperature of 500 ° C. or lower is necessary, and application was difficult under conventional conditions.

  On the other hand, in the Ti film forming apparatus 3, the shower head 60 can be heated by the heater 96 as described above, and thus the shower head 60 does not peel off regardless of the temperature of the susceptor 52. Can be. Therefore, even if the base film is a material that requires film formation at a temperature lower than 500 ° C. such as NiSi or Low-k film, a Ti film can be formed without causing film peeling. Therefore, a Ti film having a low specific resistance and a good film quality can be formed.

Actually, the susceptor set temperature and the specific resistance of the Ti film formed on the SiO ₂ film with and without temperature control (450 ° C. or higher) by heating with the heater 96 in the shower head 60. As a result of obtaining the relationship, as shown in FIG. 5, it was confirmed that a high-quality Ti film having a low specific resistance was formed by controlling the temperature of the shower head 60 to 450 ° C. or higher by the heater 96.

The actual Ti film formation is performed by the first and second embodiments described below after the wafer W is placed on the susceptor 52 as described above.
First, the first embodiment will be described.
In the first embodiment, the heater 55 and the heater 96 are maintained under the same conditions as in pre-coating, and first, high frequency power is applied from the high frequency power supply 84 to the shower head 60 as shown in the timing chart of FIG. while, TiCl ₄ gas supply source 72, a first Ar gas supply source 73, a _{H 2} gas supply source 74, TiCl ₄ gas from the second Ar gas supply source 76, an Ar gas, these gas supply _{H 2} gas The first step of generating the plasma (first plasma) and maintaining it for 4 to 8 seconds is performed. Next, only the TiCl ₄ gas is stopped, the high frequency power, the Ar gas, and the H ₂ gas are left as they are, and the second step, which is a reduction process using Ar gas and H ₂ gas plasma (second plasma), is performed for 2 to 30 seconds. Do. These first step and second step are alternately repeated a plurality of times, preferably 3 times or more, for example, about 12 to 24 times. The gas switching at this time is performed by switching the valve by the controller 98. In addition, although the plasma state changes due to such gas switching, the electronic matching network 100 automatically follows the change of the plasma based on a command from the controller 106 and changes the plasma impedance to the transmission line impedance. Because of the matching, a good plasma state is maintained. In this way, a Ti film having a predetermined thickness is formed. At this time, the gas flow rates were as follows: TiCl ₄ gas: 0.01 to 0.02 L / min (10 to 20 sccm), H ₂ gas: 1.5 to 4.5 L / min (1500 to 4500 sccm), Ar gas: 0.0. The pressure is about 8 to 2.0 L / min (800 to 2000 sccm), and the pressure is about 400 to 1000 Pa. The power of the high frequency power supply 84 is about 500 to 1500 W.

As described above, the first step of forming a film by TiCl ₄ gas + Ar gas + H ₂ gas + plasma and the second step of reducing by Ar gas + H ₂ gas + plasma are alternately performed a plurality of times in a relatively short time. Therefore, the reducing action of reducing TiCl ₄ is enhanced, and the residual chlorine concentration in the Ti film can be reduced. In particular, chlorine remains in the Ti film at a low temperature of 450 ° C. or lower. Even at such a low temperature, the residual chlorine concentration is lowered by using the sequence of this embodiment. Thus, a good film quality with a low specific resistance can be obtained.

In this way, nitriding is performed after the Ti film is formed. In this nitriding process, after the supply of high-frequency power and gas is stopped and the Ti film formation is completed, the first Ar gas is applied while applying high-frequency power from the high-frequency power source 84 to the shower head 60 as shown in FIG. Ar gas, H ₂ gas, and NH ₃ gas are supplied from the supply source 73, H ₂ gas supply source 74, NH ₃ gas supply source 75, and second Ar gas supply source 76, and the Ti film surface is formed by plasma of these gases. Nitrid. The processing time is about 30 to 60 seconds. The gas flow rate at this time is as follows: H ₂ gas: 1.5 to 4.5 L / min (1500 to 4500 sccm), Ar gas: about 0.8 to 2.0 L / min (800 to 2000 sccm), NH ₃ gas : 0.5 to 2.0 L / min (500 to 2000 sccm), and the pressure is about 400 to 1000 Pa. The power of the high frequency power supply 64 is about 500 to 1500 W.

  By performing such nitriding treatment, it is possible to prevent the Ti film from being deteriorated due to oxidation or the like and to improve the adhesion with the TiN film to be formed next. However, this nitriding treatment is not essential.

  Next, the result of comparing the case where the Ti film is actually formed based on the first embodiment and the case where the Ti film is formed by the conventional method will be described. Here, in both cases, a Ti film having a thickness of 10 nm was formed on Si at a susceptor temperature of 500 ° C., and the specific resistance was measured. In the sample of the first embodiment, a Ti film was formed by repeating a cycle of 4 seconds for the first step and 16 seconds for the second step 16 times. As a result, as shown in FIG. 7, in the case of the Ti film formed by the conventional method, the specific resistance was as high as 280 μΩ · cm due to the influence of residual chlorine, but the Ti film formed in the first embodiment The specific resistance decreased to 225 μΩ · cm.

Next, a second embodiment will be described.
In the second embodiment, the heater 55 and the heater 96 are maintained under the same conditions as in the pre-coating, and first, high frequency power is applied from the high frequency power supply 84 to the shower head 60 as shown in the timing chart of FIG. Meanwhile, TiCl ₄ gas, Ar gas, and H ₂ gas are supplied from the TiCl ₄ gas supply source 72, the first Ar gas supply source 73, the H ₂ gas supply source 74, and the second Ar gas supply source 76. A first step of generating a gas plasma (first plasma) and maintaining it for 4 to 8 seconds is performed. Then, it maintains the Ar gas, _{H 2} gas, a high-frequency power is stopped to stop the TiCl ₄ gas, and start supplying the NH ₃ gas from the NH ₃ gas supply source 75, and resumes the supply of the high-frequency power Then, the second step, which is a reduction / nitridation process using Ar gas, H ₂ gas, and NH ₃ gas plasma (second plasma), is performed for 4 to 8 seconds. These first step and second step are alternately repeated a plurality of times, preferably 3 times or more, for example, about 12 to 24 times. The gas switching at this time is performed by switching the valve by the controller 98. Further, in response to such a change in the plasma state due to the gas switching, the electronic matching network 100 automatically follows the change in the plasma based on a command from the controller 106 and transmits the plasma impedance to the transmission line. Match to impedance. In this way, a Ti film having a predetermined thickness is formed. At this time, the gas flow rates were as follows: TiCl ₄ gas: 0.01 to 0.02 L / min (10 to 20 sccm), H ₂ gas: 1.5 to 4.5 L / min (1500 to 4500 sccm), NH ₃ gas: 0 0.5 to 2.0 L / min (500 to 2000 sccm), Ar gas: 0.8 to 2.0 L / min (800 to 2000 sccm), and the pressure is about 400 to 1000 Pa. The power of the high frequency power supply 84 is about 500 to 1500 W.

Thus, the first step of forming a film by TiCl ₄ gas + Ar gas + H ₂ gas + plasma and the second step of performing reduction and nitridation by NH ₃ gas + Ar gas + H ₂ gas + plasma in a relatively short time. Since it is performed a plurality of times alternately, the reduction action of reducing TiCl ₄ is enhanced, and the Ti film can be effectively nitrided to prevent the Ti film from being deteriorated, so that residues such as chlorine can be reduced. Thus, a high-quality Ti film having a low specific resistance can be obtained. In particular, chlorine remains in the Ti film at a low temperature of 450 ° C. or lower. Even at such a low temperature, the residual chlorine concentration is lowered by using the sequence of this embodiment. Thus, a good film quality with a low specific resistance can be obtained.

In the present embodiment, the Ti / TiN film can also be formed by controlling the amount of NH ₃ gas in the second step and the time of the second step. That is, when the supply amount of NH ₃ gas is small or the time of the second step is short, nitriding is auxiliary and the formed film functions as a Ti film, but the supply amount of NH ₃ gas is When there are many or when the time of the second step is long, a sufficient amount of TiN film can be formed, and a laminated film in which Ti films and TiN films are alternately laminated can be obtained. Such a laminated film can function as a Ti / TiN film, and a Ti / TiN film can be formed with one kind of apparatus. In this case, the TiN film forming apparatus 4 is not necessary or is auxiliary even if necessary.

  Next, the result of comparing the case where the Ti film was actually formed based on the second embodiment and the case where the Ti film was formed by the conventional method will be described. Here, in both cases, a Ti film having a thickness of 10 nm was formed on Si at a susceptor temperature of 500 ° C., and the specific resistance was measured. In the sample of the second embodiment, a Ti film was formed by repeating a cycle of the first step for 4 seconds and the second step for 4 seconds 16 times. As a result, as shown in FIG. 9, in the case of the Ti film formed by the conventional method, the specific resistance was as high as 280 μΩ · cm due to the influence of residual chlorine, but the Ti film formed in the second embodiment The specific resistance was remarkably reduced to 130 μΩ · cm. However, in this case, since the time of the second step was long, it is considered that a TiN film was also formed slightly. Therefore, it is considered that the specific resistance of the sample based on the second embodiment also includes some decrease due to the formation of the TiN film.

Next, the TiN film forming apparatus 4 will be described.
FIG. 10 is a cross-sectional view showing the TiN film forming apparatus 4. The TiN film forming apparatus 4 has substantially the same configuration as the Ti film forming apparatus 3 except that there is no means for heating the plasma generating means and the shower head, and the gas system of the gas supply mechanism is slightly different. Therefore, except for the gas supply mechanism, the same reference numerals as those in FIG.

The gas supply mechanism 110 includes a ClF ₃ gas supply source 111 that supplies a ClF ₃ gas that is a cleaning gas, a TiCl ₄ gas supply source 112 that supplies a TiCl ₄ gas that is a Ti-containing gas, and a first N ₂ gas that supplies N ₂ gas. N ₂ gas supply source 113, and a second _{N 2} gas supply source 115 for supplying the NH ₃ gas supply source 114, _{N 2} gas supplied NH ₃ gas is a gas nitriding. The ClF ₃ gas supply source 111 has a ClF ₃ gas supply line 116, the TiCl ₄ gas supply source 112 has a TiCl ₄ gas supply line 117, and the first N ₂ gas supply source 113 has a first N ₂ The gas supply line 118 is connected to the NH ₃ gas supply source 114, the NH ₃ gas supply line 119 is connected to the second N ₂ gas supply source 115, and the second N ₂ gas supply line 120 is connected to the second N ₂ gas supply source 115. Although not shown, it also has an Ar gas supply source. Each gas supply line is provided with two valves 121 sandwiching the mass flow controller 122 and the mass flow controller 122.

A TiCl ₄ gas supply line 117 extending from the TiCl ₄ gas supply source 112 is connected to the first gas inlet 61 of the shower head 60, and this TiCl ₄ gas supply line 117 extends from the ClF ₃ gas supply source 111. A ClF ₃ gas supply line 116 and a first N ₂ gas supply line 118 extending from the first N ₂ gas supply source 113 are connected. Further, an NH ₃ gas supply line 119 extending from the NH ₃ gas supply source 114 is connected to the second gas introduction port 62, and the second N ₂ gas supply source 115 is connected to the NH ₃ gas supply line 119. A second N ₂ gas supply line 120 extending from is connected. Therefore, when the process, TiCl ₄ gas is the first gas introducing showerhead 60 through the TiCl ₄ gas supply line 117 with _{N 2} gas from the first _{N 2} gas supply source 113 from the TiCl ₄ gas supply source 112 It reaches the mouth 61 to the shower head 60, while being discharged from the discharge hole 67 through the gas passage 63 and 65 into the chamber 51, the NH ₃ gas is a nitriding gas from the NH ₃ gas supply source 114 of the 2 N Along with N ₂ gas from the _two gas supply sources 115, the NH ₃ gas supply line 119 is connected to the shower head 60 through the second gas inlet 62 of the shower head 60, and from the discharge hole 68 through the gas passages 64 and 66. It is discharged into the chamber 51. In other words, the shower head 60 is a matrix type in which TiCl ₄ gas and NH ₃ gas are supplied into the chamber 51 completely independently, and these are mixed and reacted after discharge. The valve 121 and the mass flow controller 122 are controlled by the controller 123.

Next, a TiN film forming method using such an apparatus will be described.
First, the inside of the chamber 51 is cut off by the exhaust device 88 and the heater 55 is introduced while introducing the N ₂ gas from the first and second N ₂ gas supply sources 113 and 115 into the chamber 51 through the shower head 60. To preheat the chamber 51. When the temperature is stabilized, N ₂ gas, NH ₃ gas, and TiCl ₄ gas are respectively supplied from the first N ₂ gas supply source 113, the NH ₃ gas supply source 114, and the TiCl ₄ gas supply source 112 through the shower head 60. Introducing at a predetermined flow rate, preflow is performed while maintaining the pressure in the chamber at a predetermined value. Then, with the gas flow rate and pressure kept the same, a TiN film is precoated on the inner wall of the chamber 51, the inner wall of the exhaust chamber 86, and the surface of the chamber inner member such as the shower head 60 by heating with the heater 55.

After the pre-coating process is finished, the NH ₃ gas and TiCl ₄ gas are stopped, and the first and second N ₂ gas supply sources 113 and 115 supply the N ₂ gas as a purge gas into the chamber 51 to purge the chamber 51 After that, if necessary, N ₂ gas and NH ₃ gas are flowed to perform a nitride treatment on the surface of the formed TiN thin film.

Thereafter, the inside of the chamber 51 is abruptly evacuated by the evacuation device 88 to bring it into a drawn state, the gate valve G is opened, and the wafer W is transferred from the wafer transfer chamber 1 in the vacuum state through the loading / unloading port 92 by the wafer transfer device 12. Is carried into the chamber 51. Then, N ₂ gas is supplied into the chamber 51 to preheat the wafer W. When the wafer temperature is substantially stabilized, the TiN film formation is started.

The TiN film is formed according to the first and second embodiments described below. In the first embodiment, first, N ₂ gas and NH ₃ gas are introduced at a predetermined flow rate through the shower head 60, and TiCl ₄ gas is preflowed while maintaining the chamber pressure at a predetermined value. Then, TiCl ₄ gas is introduced into the chamber while keeping the gas flow rate and the pressure in the chamber 51 the same. At this time, since the wafer W is heated by the heater 55, a TiN film is formed on the Ti film of the wafer W by thermal CVD. In this way, a Ti film having a predetermined thickness is formed by flowing N ₂ gas, NH ₃ gas, and TiCl ₄ gas for a predetermined time. At this time, the gas flow rates were as follows: TiCl ₄ gas: 0.03 to 0.10 L / min (30 to 100 sccm), N ₂ gas: 0.8 to 2.0 L / min (800 to 2000 sccm), NH ₃ gas: 0 The pressure is about 0.03 to 1 L / min (30 to 1000 sccm), and the pressure is about 200 to 10,000 Pa. The heating temperature of the wafer W at this time is about 400 to 700 ° C., preferably about 500 ° C.

After completion of the film forming process, the NH ₃ gas and TiCl ₄ gas are stopped, and N ₂ gas is supplied as a purge gas from a purge gas line (not shown), preferably at a flow rate of 0.5 to 10 L / min. After that, N ₂ gas and NH ₃ gas are allowed to flow to perform a nitride treatment on the surface of the TiN thin film formed on the wafer W. At this time, the supply of N ₂ gas is performed from one or both of the first and second N ₂ gas supply sources 113 and 115. This nitride treatment is not essential.

After a predetermined time has elapsed, the N ₂ gas and NH ₃ gas are gradually stopped, and the film formation process is terminated when the supply of these gases is completely stopped.

Next, a second embodiment of TiN film formation will be described. The temperature of the wafer W by the heater 55 is maintained at about 400 to 700 ° C. in the same manner as described above. As shown in the timing chart of FIG. 11, first, the TiCl ₄ gas supply source 112 and the NH ₃ gas supply source 114 receive TiCl _4. The first step of forming a TiN film by thermal CVD is performed by making the gas, NH ₃ gas, carrier into the N ₂ gas from the first and second N ₂ gas supply sources 113 and 115 and supplying it into the chamber 51. Perform for 2-8 seconds. Next, the TiCl ₄ gas and NH ₃ gas are stopped, N ₂ gas is introduced into the chamber 51 as a purge gas from a purge gas line (not shown), and the chamber 51 is purged for 0.5 to 20 seconds. Thereafter, 0.5 a second step of performing annealing NH ₃ gas from the NH ₃ gas supply source 114, by the carrier to the _{N 2} gas from the second _{N 2} gas supply source 115 is supplied to the chamber 51 Perform for 8 seconds. Next, the NH ₃ gas is stopped, N ₂ gas is introduced into the chamber 51 as a purge gas from a purge gas line (not shown), and the purge in the chamber 51 is performed for 0.5 to 20 seconds. The above process is repeated as a cycle for a plurality of cycles, preferably 3 cycles or more, for example, about 12 to 24 times. The gas switching at this time is performed by switching the valve by the controller 123.

  By performing the alternate gas flow in this way, the TiN film formed in the first step can be efficiently de-Cl by the second step annealing, and the residual chlorine in the film can be significantly reduced, Even in the case of low-temperature film formation, a high-quality TiN film with little residual chlorine can be formed.

  Even when any of the above TiN films is formed, the underlying Ti film is formed by the process using the alternate gas flow shown in the first embodiment or the second embodiment as described above. Therefore, it is possible to obtain a state in which film peeling between the Ti film and the TiN film hardly occurs, and the film quality of the entire Ti / TiN film becomes better than before. Note that when the Ti film is formed by a conventional gas flow, film peeling between the Ti film and the TiN film occurs frequently regardless of which method is used to form the TiN film.

  Next, the presence or absence of film peeling of a sample manufactured by performing pre-cleaning, Ti film formation, and TiN film formation in situ by the film formation system of FIG. As a sample at this time, a Ti film formed in the first and second embodiments and a TiN film formed thereon by the above two methods were used. Tables 1 and 2 show the conditions at that time. For comparison, after the Ti film was formed under the conditions for forming a conventional Ti film (also shown in Table 1), the presence or absence of film peeling was also investigated for the sample on which the TiN film was formed. The film peeling was grasped by visual observation and discoloration (the part where the film peeling occurred was discolored).

  As a result, when the Ti film was formed under the above-mentioned conditions within the range of the first and second embodiments, peeling of the film and discoloration by visual observation were completely observed regardless of which method was used to form the TiN film. In other words, it was confirmed that no film peeling occurred. On the other hand, when the Ti film was formed by the conventional method, film peeling and discoloration were confirmed regardless of which method was used to form the TiN film. In addition, it was confirmed that the Ti / TiN film sample in which the Ti film was formed under the above conditions within the range of the first and second embodiments had lower electrical resistance and better film quality than the conventional one. .

Next, a method for forming a Ti / TiN film by using only the Ti film forming apparatus 3 without using the TiN film forming apparatus 4 will be described with reference to FIG.
Here, the heater 55 and the heater 96 are maintained under the same conditions as in pre-coating, and as shown in the timing chart of FIG. 12, first, while applying high-frequency power from the high-frequency power source 84 to the shower head 60, TiCl ₄ TiCl ₄ gas, Ar gas, and H ₂ gas are supplied from the gas supply source 72, the first Ar gas supply source 73, the H ₂ gas supply source 74, and the second Ar gas supply source 76, and plasma (first) of these gases is supplied. 1 plasma) is generated and maintained for 4 to 8 seconds. Next, only the TiCl ₄ gas is stopped, the high frequency power, the Ar gas, and the H ₂ gas are left as they are, and the second step, which is a reduction process using Ar gas and H ₂ gas plasma (second plasma), is performed for 2 to 30 seconds. Do. The first step and the second step are alternately repeated a plurality of times, preferably 3 times or more, for example, about 12 to 24 times, and a Ti film is first formed. At this time, the gas flow rates were as follows: TiCl ₄ gas: 0.01 to 0.02 L / min (10 to 20 sccm), H ₂ gas: 1.5 to 4.5 L / min (1500 to 4500 sccm), Ar gas: 0.0. The pressure is about 8 to 2.0 L / min (800 to 2000 sccm), and the pressure is about 400 to 1000 Pa. The power of the high frequency power supply 84 is about 500 to 1500 W.

After the Ti film is formed in this way, the TiN film is subsequently formed. The TiN film is formed by stopping the supply of high-frequency power and gas and finishing the Ti film formation, and then heating the susceptor 52 to 450 to 550 ° C. by the heater 55 and the shower head 60 by the heater 96 at 450 ° C. It heats to the above temperature, for example, about 470-490 degreeC. Then, as shown in FIG. 12, first, while applying high frequency power from the high frequency power supply 84 to the shower head 60, the TiCl ₄ gas supply source 72, the first Ar gas supply source 73, the H ₂ gas supply source 74, A third step of supplying TiCl ₄ gas, Ar gas, and H ₂ gas from the second Ar gas supply source 76 to generate plasma of these gases (third plasma) and maintaining it for 4 to 12 seconds. Do. Then, it maintains the Ar gas, _{H 2} gas, a high-frequency power is stopped to stop the TiCl ₄ gas, and start supplying the NH ₃ gas from the NH ₃ gas supply source 75, and resumes the supply of the high-frequency power Then, the fourth step, which is a reduction / nitridation process using Ar gas, H ₂ gas, and NH ₃ gas plasma (fourth plasma), is performed for 2 to 30 seconds. The third step and the fourth step are alternately repeated a plurality of times, preferably three times or more, for example, about 12 to 24 times to form a TiN film on the Ti film. At this time, the gas flow rates were as follows: TiCl ₄ gas: 0.01 to 0.02 L / min (10 to 20 sccm), H ₂ gas: 1.5 to 4.5 L / min (1500 to 4500 sccm), NH ₃ gas: 0 0.5 to 1.5 L / min (500 to 1500 sccm), Ar gas: 0.8 to 2.0 L / min (800 to 2000 sccm), and the pressure is about 400 to 1000 Pa. The power of the high frequency power supply 84 is about 500 to 1500 W.

  The gas switching at this time is performed by switching the valve by the controller 98. Further, in response to such a change in the plasma state due to the gas switching, the electronic matching network 100 automatically follows the change in the plasma based on a command from the controller 106 and transmits the plasma impedance to the transmission line. Match to impedance.

As described above, the first step of forming a film by TiCl ₄ gas + Ar gas + H ₂ gas + plasma and the second step of reducing by Ar gas + H ₂ gas + plasma are alternately performed a plurality of times in a relatively short time. A third step of forming a Ti film, and subsequently forming a film by TiCl ₄ gas + Ar gas + H ₂ gas + plasma, and a fourth step of performing reduction and nitridation by NH ₃ gas + Ar gas + H ₂ gas + plasma, Since the TiN film is formed by alternately performing a plurality of times in a relatively short time, the reducing action of reducing the Ti compound is enhanced and nitriding can be performed effectively. For this reason, the residual chlorine concentration in the Ti film can be reduced. In particular, chlorine remains in the Ti film or TiN film at a low temperature of 450 ° C. or lower. Even at such a low temperature, the residual chlorine concentration can be obtained by using the sequence of this embodiment. And a Ti / TiN multilayer structure with a low specific resistance and good film quality can be obtained. In addition, since a Ti / TiN laminated structure, which conventionally required two kinds of film forming apparatuses, can be continuously formed with one film forming apparatus, it is extremely efficient.

In the third step and fourth step, in order to obtain a good TiN film is a Ti film formed in the third step ensures there is a need to nitriding in the fourth step, NH ₃ gas flow rate and the order thereof It is preferable to adjust the time of 4 steps. In particular, it is preferable to set the time of the fourth step to be equal to or longer than the time of the third step.

  In this way, the Ti / TiN film can be formed with one kind of film forming apparatus, and therefore, when this method is used, the TiN film forming apparatus 4 is unnecessary.

The present invention can be variously modified without being limited to the above embodiment. For example, although the case where a Ti film is formed has been described in the above embodiment, the present invention is not limited to this, and is also effective for other films formed by plasma CVD. The Ti compound is not limited to TiCl ₄ , and other halogen compounds such as TiF ₄ and TiI ₄ and other compounds can be used. Reducing gas is also not limited to H _2. The gas containing N and H is not limited to NH ₃ gas, and a mixed gas of N ₂ and H ₂ or the like can be used. Furthermore, in the above-described embodiment, a semiconductor wafer is used as a substrate to be processed. However, the present invention is not limited to this, and another substrate such as a liquid crystal display (LCD) substrate may be used.

  According to the present invention, it is possible to form a Ti film even when the temperature of the substrate to be processed at the time of film formation is as low as about 450 ° C. Since a Ti film with a low specific resistance and a good quality can be obtained, it is suitable for film formation on NiSi or a capacitor film with low heat resistance.

  Further, according to the present invention, when the Ti film is formed, the mounting table and the gas discharge member can be heated independently of each other, and the temperature of the gas discharge member is always controlled to 450 ° C. or higher. Therefore, even when the film is formed at a low temperature, the gas discharge member can be prevented from peeling off, and can be applied to film formation on NiSi or a capacitor film having low heat resistance.

1 is a schematic configuration diagram showing a multi-chamber type film forming system equipped with a Ti film forming apparatus for carrying out an embodiment of a film forming method of the present invention. Sectional drawing which shows the via-hole part of the semiconductor device which formed Ti / TiN film | membrane. Sectional drawing which shows the pre-cleaning apparatus mounted in the film-forming system of FIG. Sectional drawing which shows the Ti film | membrane film-forming apparatus used for implementation of this invention mounted in the film-forming system of FIG. The graph which shows the relationship between the susceptor temperature at the time of film-forming, and the specific resistance value of Ti film | membrane in the case of with and without temperature control of a shower head. The timing chart which shows the timing of gas supply and high frequency electric power supply of 1st Embodiment of Ti film forming method. The graph which shows the effect by 1st Embodiment of Ti film forming method. The timing chart which shows the timing of gas supply and high frequency electric power supply of 2nd Embodiment of Ti film forming method. The graph which shows the effect by 2nd Embodiment of Ti film forming method. Sectional drawing which shows the TiN film | membrane film-forming apparatus mounted in the film-forming system of FIG. The timing chart which shows the timing of the gas supply of 2nd Embodiment of the TiN film forming method. The timing chart which shows the timing of the gas supply and high frequency electric power supply in the case of forming Ti / TiN with the same apparatus based on this invention.

Explanation of symbols

2 ... Pre-cleaning device 3 ... Ti film deposition device 4 ... TiN film deposition device 51 ... Chamber 52 ... Susceptor 55, 96 ... Heater 60 ... Shower head 70 ... Gas supply mechanism 98 ... Controller 100 …… Electronic matching network W …… Semiconductor wafer

Claims (3)

A step of removing a natural oxide film on the surface of the substrate to be processed in the first processing chamber by plasma, and a step of forming a Ti film on the substrate to be processed in the second processing chamber by CVD;
The step of forming the Ti film includes a first step of generating a first plasma while introducing a Ti compound gas and a reducing gas, and a second plasma while stopping the Ti compound gas and introducing the reducing gas. A film forming method, wherein the generated second step is alternately repeated a plurality of times. A substrate to be processed is mounted on a mounting table in a processing chamber, and a Ti compound gas and a reducing gas are discharged from a gas discharge member provided facing the mounting table, and plasma is generated in the processing chamber. A film forming method for forming a Ti film on a substrate to be processed by plasma CVD,
The mounting table and the gas discharge member can be heated independently of each other. The mounting table is heated to control the temperature of the substrate to be processed at 300 to 700 ° C., and the gas discharge member is heated to A film forming method characterized in that the temperature is controlled to 450 ° C. or higher. The film forming method according to claim 2, wherein the temperature of the substrate to be processed is controlled to be 300 ° C. or higher and lower than 550 ° C. by heating the mounting table.

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