JP2004225162A - Film deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition method of a film to be deposited by plasma CVD which is capable of performing low-temperature film deposition, and reducing residues in a film even in the low-temperature film deposition. <P>SOLUTION: When depositing a Ti film by CVD on a work substrate in a treatment chamber, a first step of generating first plasma while introducing TiCl<SB>4</SB>gas, H<SB>2</SB>gas and Ar gas, and a second step of generating second plasma while stopping the feed of TiCl<SB>4</SB>gas and introducing H<SB>2</SB>gas and Ar gas are alternately repeated for a plurality of times. The first plasma and the second plasma are changed over to follow the alternate gas change-over. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a film forming method including the formation 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 be a multilayer wiring structure. Therefore, the connection between a lower semiconductor substrate and an upper wiring layer has been required. An embedding technique for electrical connection between layers such as a contact hole as a portion and a via hole as a connection portion between upper and lower wiring layers has become important.

  Generally, Al (aluminum), W (tungsten), or an alloy containing these as a main component is used for filling such contact holes and via holes. Such a metal or alloy and a lower Si substrate or poly are used. In order to form a contact with a -Si layer, a Ti film is formed inside a contact hole or a via hole prior to the filling, and a TiN film is formed as a barrier layer.

  Conventionally, such a Ti film and a TiN film have been formed using physical vapor deposition (PVD). However, recently, miniaturization and high integration of devices have been particularly required, and design rules have been particularly restricted. As the line width and hole opening diameter become smaller and the aspect ratio becomes higher, the electrical resistance of the PVD film increases, making it difficult to meet the demand.

Therefore, these Ti films and TiN films are formed by chemical vapor deposition (CVD), which can be expected to form higher quality films. In the formation of these films, TiCl 4 with _(titanium tetrachloride) as a deposition gas, while the semiconductor wafer is a substrate heated by the stage heater, by reacting TiCl ₄ and H _{2 (hydrogen)} A Ti film is formed, and a TiN film is formed by reacting TiCl ₄ with 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, low-temperature film formation has been aimed at, and in that case, the chlorine concentration in the film becomes higher.

To solve such a problem of residual chlorine, Patent Document 1 discloses that when forming a TiN film, (1) supply TiCl ₄ gas, (2) stop TiCl ₄ gas, and supply purge gas to supply TiCl _4. removing the gas, (3) to stop the purge gas supplying NH ₃ gas, (4) the NH ₃ gas is stopped, technique of repeating the steps such removal of NH ₃ by supplying a purge gas are disclosed. According to this technique, the residual chlorine can be reduced, and the film can be formed at a lower temperature.

On the other hand, in the case of a Ti film, since the film is formed by plasma CVD, it is difficult to maintain a plasma maintaining an appropriate matching state with the transmission impedance when such alternate gas switching is performed. It is considered that such a method is not used for forming the Ti film, and the film is formed at a relatively high temperature of 600 ° C. or more under the condition of simultaneously flowing TiCl ₄ and H _2, and the residual chlorine is formed. The problem has been solved.

  By the way, recently, silicide such as CoSi or NiSi, which has better contact characteristics, is being used instead of poly-Si from the viewpoint of speeding up the device. Among them, NiSi has attracted attention as a logic contact.

  However, NiSi has low heat resistance, and when a Ti film is formed thereon by CVD, it is necessary to set the film forming temperature to a low temperature of about 450 ° C. At such a low temperature, the film is formed by a conventional method. It is difficult to perform the process, and even if a film can be formed, the film has a high residual chlorine concentration and a poor film quality. In addition, when a Ti film is formed, a Ti film is also formed in advance on a shower head that is a gas discharge member. However, in the case of a low-temperature film formation, a heating temperature of a susceptor on which a wafer is mounted is low. The temperature of the gas discharge shower head provided opposite to the susceptor also becomes low, 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 TiN film is formed thereon 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-A-11-172438

  The present invention has been made in view of such circumstances, and in forming a film formed by plasma CVD, low-temperature film formation is possible, and even in low-temperature film formation, residues in the film are removed. It is an object of the present invention to provide a film formation method capable of reducing the number of films.

  Further, the present invention provides a film forming method in which when a Ti film is formed thereon after forming a Ti film, even if the Ti film is formed at a low temperature, film peeling does not occur between them. The purpose is to do.

  In order to solve the above problems, according to a first aspect of the present invention, a compound gas containing a component of a film to be formed on a substrate to be processed in a processing chamber and a reducing gas are supplied, and plasma is supplied into the chamber. A first step of generating a first plasma while introducing the compound gas and the reducing gas, and stopping the compound gas. The second step of generating the second plasma while introducing the reducing gas is alternately repeated a plurality of times, so that the first plasma and the second plasma follow the alternating gas switching. A film forming method characterized by being switched to

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

  According to a second aspect of the present invention, there is provided a film forming method for forming a Ti film on a substrate to be processed by CVD in a processing chamber, wherein a first plasma is generated while introducing a Ti compound gas and a reducing gas. The first step and the second step of stopping the Ti compound gas and generating the second plasma while introducing the reducing gas are alternately repeated a plurality of times, and the first plasma and the second plasma are There is provided a film forming method characterized by being switched so as to follow alternate gas switching.

  In this case, after repeating the first step and the second step 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.

  According to a third aspect of the present invention, there is provided a film forming method for forming a Ti or Ti / TiN film on a substrate to be processed in a processing chamber by CVD, wherein the first plasma is introduced while introducing a Ti compound gas and a reducing gas. And a second step of generating a second plasma while stopping the Ti compound gas and introducing the reducing gas and the gas containing N and H is repeated a plurality of times. And the second plasma are switched so as to follow the alternate gas switching.

In the second and third aspects, TiCl ₄ gas may be used as the Ti compound gas, H ₂ gas may be used as the reducing gas, and a rare gas such as Ar, He, or Xe may be introduced in all the steps. it can. Further, NH ₃ gas can be used as the gas containing N and H. Further, the temperature of the substrate to be processed can be set to 300 to 700 ° C. during the processing while the substrate to be processed is mounted on the mounting table. Furthermore, it is preferable to remove the natural oxide film on the surface of the base before forming the Ti film.

  In any of the above film forming methods, the plasma is generated by supplying high-frequency power to at least one of the pair of parallel plate electrodes, and matching between the plasma impedance and the transmission line impedance is performed by an electronic matching type matching network. Is preferred. Since such an electron matching type matching network can follow a change in the plasma state in a short time, it can sufficiently cope with such an alternate gas switching.

  According to a first aspect of the present invention, a first step of generating a first plasma while introducing a compound gas and a reducing gas, and a step of stopping the compound gas and introducing a second plasma while introducing the reducing gas. The second step to be generated is alternately repeated a plurality of times, preferably three or more times, and at this time, the first plasma and the second plasma are switched so as to follow the alternating gas switching. By doing so, effective reduction can be performed, film formation can be performed at lower temperature, residues in the film can be reduced, and a film with better film quality can be formed. it can.

  According to a second aspect of the present invention, a first step of generating a first plasma while introducing a Ti compound gas and a reducing gas, and a second step of stopping the Ti compound gas and introducing the reducing gas are performed. And the second step of generating the plasma is alternately repeated a plurality of times, preferably three or more times. At this time, the first plasma and the second plasma follow the alternate gas switching. By switching to, the Ti compound can be effectively reduced, so that the Ti film can be formed even when the temperature of the substrate to be processed at the time of film formation is as low as about 450 ° C. In addition, even if the film is formed at a low temperature, residues such as chlorine can be reduced, and a high-quality Ti film having a low specific resistance can be obtained.

  Further, according to a third aspect of the present invention, a first step of generating a first plasma while introducing a Ti compound gas and a reducing gas, and stopping the Ti compound gas to reduce the reducing gas and N and H Alternately repeating the second step of generating the second plasma while introducing the containing gas a plurality of times, in which case the first plasma and the second plasma follow the alternating gas switching. In this case, the Ti compound can be effectively reduced, and the Ti film can be effectively nitrided to prevent the Ti film from deteriorating. Film formation is possible even when the temperature of the substrate to be processed is as low as 450 ° C. or less, and even at such a low temperature film formation, residues such as chlorine can be reduced, and high quality with low specific resistance can be obtained. Obtaining a proper Ti film It can be. Further, by controlling the amount and supply time of the gas containing N and H, it can be used as a Ti film or as a Ti / TiN film.

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 implementing an embodiment of the film forming method of the present invention.

  As shown in FIG. 1, the film forming system 100 includes a hexagonal wafer transfer chamber 1, and connection ports 1a, 1b, and 1c to which predetermined processing apparatuses are connected on four sides. , 1d, a pre-cleaning device 2 for removing a natural oxide film on a film formation base of a semiconductor wafer W to be processed is connected to the connection port 1a, and a Ti film is formed on the connection port 1b by plasma CVD. A Ti film forming apparatus 3 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 needed. Load lock chambers 6 and 7 are provided on the other two sides of the wafer transfer chamber 1, respectively. A wafer loading / unloading chamber 8 is provided on the opposite side of the load lock chambers 6, 7 from the wafer transfer chamber 1, and a wafer W can be stored on the opposite side of the wafer loading / unloading chamber 8 from the load lock chambers 6, 7. Ports 9, 10, and 11 for attaching three FOUPs (FOUP) 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 gate valves G as shown in FIG. When opened, it communicates with the wafer transfer chamber 1, and is closed off from the wafer transfer chamber 1 by closing each gate valve G. A gate valve G is also provided at a portion of the load lock chambers 6, 7 connected to the wafer loading / unloading chamber 8, and the load lock chambers 6, 7 are opened and closed 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, a wafer W, which is an object to be processed, is carried in 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 14a and 14b that hold the wafer W at the tip of a rotatable and expandable portion 13 that can rotate and expand. The two blades 14a and 14b are attached to the rotating / expandable portion 13 so as to face in opposite directions. The inside of the wafer transfer chamber 1 is maintained at a predetermined degree of vacuum.

  A HEPA filter (not shown) is provided on the ceiling of the wafer loading / unloading chamber 8, and clean air that has passed through the HEPA filter is supplied into the wafer loading / unloading chamber 8 in a downflow state. The transfer of the wafer W is performed in a clean air atmosphere. Shutters (not shown) are provided at the three ports 9, 10, and 11 for attaching the FOUP F of the wafer loading / unloading chamber 8, respectively. The hoop is directly attached, and when attached, the shutter is released to prevent intrusion of outside air and communicate with the wafer carry-in / out chamber 8. Further, an alignment chamber 15 is provided on a side surface of the wafer loading / unloading chamber 8, where the alignment of the wafer W is performed.

  In the wafer loading / unloading chamber 8, a wafer transfer device 16 for loading / unloading the wafer W into / from the hoop 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, is capable of running on rails 18 along the direction in which the hoops F are arranged, and places the wafer W on a hand 17 at the tip thereof to transfer the wafer W. I do.

  The control of the entire system such as the operation 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 any one of the FOUPs F by the wafer transfer device 16 in the wafer loading / unloading chamber 8 kept in a clean air atmosphere at atmospheric pressure, and the alignment chamber is removed. The wafer W is loaded into the wafer 15 and 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. Then, the wafer in the load lock chamber is taken out by the wafer transfer device 12 in the wafer transfer chamber 1, and the wafer W is removed. Is loaded into the pre-cleaning device 2 to remove the natural oxide film on the underlying surface, and then the wafer W is loaded into the Ti film forming device 3 to form a Ti film. Is continuously loaded into the TiN film forming apparatus 4 to form a TiN film. That is, in the film forming system 100, the natural oxide film removal, the Ti film formation, and the TiN film formation are performed in situ without breaking the vacuum. Thereafter, the wafer W after the film formation is carried into one of the load lock chambers 6 and 7 by the wafer transfer device 12 and the inside thereof is returned to the atmospheric pressure, and then the load is locked by the wafer transfer device 16 in the wafer transfer chamber 8. The wafer W in the room is taken out and stored in one of the hoops F. Such an operation is performed on one lot of wafers W, and the processing of one lot is completed.

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

Next, the pre-cleaning device 2 will be described.
The pre-cleaning device 2 is of an inductively coupled plasma (ICP) type and is for removing a poly-Si or silicide natural oxide film serving as a base. As shown in FIG. And a substantially cylindrical bell jar 32 provided above the chamber 31 so as to be continuous with the chamber 31. In 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 arranged in a state supported by a cylindrical support member. A clamp ring 35 for clamping the wafer W is provided at an outer edge of the susceptor 33. A heater 36 for heating the wafer W is embedded in the susceptor 33, and the heater 36 heats the wafer W, which is a processing target, to a predetermined temperature by being supplied with power from a heater power supply 39.

  The bell jar 32 is made of, for example, an electrically insulating material such as quartz or a ceramic material, and a coil 37 as an antenna member is wound therearound. 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. By supplying high-frequency power from the high-frequency power supply 38 to the coil 37, an induction electromagnetic field is formed in the bell jar 32.

  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, a pipe from each gas supply source, an opening / closing valve, and a mass flow controller (flow rate control). (Both are not shown). A gas introduction nozzle 42 is provided on a side wall of the chamber 31, and a pipe 41 extending from the gas supply mechanism 40 is connected to the gas introduction nozzle 42, and a predetermined gas is supplied to the chamber 31 through the gas introduction nozzle 42. Introduced within. 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 them, 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. By operating the exhaust device 44, the pressure inside the chamber 31 and the bell jar 32 can be reduced to a predetermined degree of vacuum.

  Further, a gate valve G is provided on the side wall of the chamber 31, and is connected to the wafer transfer chamber 1 via the gate valve G as described above.

  Further, in the susceptor 33, for example, an electrode 45 formed by braiding a molybdenum wire or the like in a mesh shape is embedded, and a high frequency power supply 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 inside of the chamber 31 and the bell jar 32 is exhausted by the exhaust device 44 to a predetermined reduced pressure state, and then the predetermined gas is supplied from the gas supply mechanism 40 into the chamber 31 via the gas introduction nozzle 42. For example, by introducing 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, inductively coupled plasma is generated. On the other hand, high frequency power is supplied to the susceptor 33 from the high frequency power supply 46, and ions are drawn into the wafer W.

  In this way, the inductively coupled plasma acts on 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 sectional view showing the Ti film forming apparatus 3. The Ti film forming apparatus 3 has a substantially cylindrical chamber 51 which is airtightly arranged, and a susceptor 52 for horizontally supporting a wafer W to be processed is provided in a lower central portion thereof. Are arranged in a state where they are supported by a cylindrical support member 53 provided in the main body. The susceptor 52 is made of ceramics such as AlN, and a guide ring 54 for guiding the wafer W is provided at an outer edge thereof. Further, a heater 55 is embedded in the susceptor 52, and the heater 55 is heated by a heater power supply 56 to heat the wafer W, which is a substrate to be processed, to a predetermined temperature. An electrode 58 functioning as a lower electrode is embedded in the susceptor 52 above the heater 55.

  A shower head 60 is provided on a 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 from a heater power supply 97 to heat the shower head 60 to a predetermined temperature. 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 60a, a 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 the 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 number of gas passages 64 are branched from the second gas inlet 62. Gas passages 66 are formed in the middle block body 60b, and the gas passages 64 communicate with the gas passages 66. Further, the gas passage 66 is connected to a communication passage 66a extending horizontally in 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 an 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 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 73. 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 The supply lines 80b are respectively connected. Although not shown, it also has an N ₂ gas supply source. Each gas supply line is provided with a mass flow controller 82 and two valves 81 with the mass flow controller 82 interposed therebetween.

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 supply line 77 and a first Ar gas supply line 79 extending from the first Ar gas supply source 73 are connected. 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 extends from an NH ₃ gas supply source 75 to the H ₂ gas supply line 80. The NH ₃ gas supply line 80a and the second Ar gas supply line 80b 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 Ar gas from the source 76 flows into the shower head 60 from the second gas inlet 62 of the shower head 60 via the H ₂ gas supply gas line 80, and from the discharge hole 68 to the inside of the chamber 51 through the gas passages 64 and 66. Is discharged to That is, the shower head 60 is of a matrix type in which the TiCl ₄ gas and the H ₂ gas are supplied into the chamber 51 completely independently, and these are mixed after ejection to cause a reaction. 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 The liquid is introduced into the shower head 60 through the port 62 and discharged from the discharge port 68. The valve 81 and the mass flow controller 82 are controlled by a controller 98 so as to supply gas alternately 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 type matching network 100. High frequency power is supplied to the shower head 60 via the 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. The reflected wave from the plasma is input to the controller 106 via the transmission line 83, and the controller 106 controls the electronic matching network 100 so that the reflected wave from the plasma becomes zero or minimum. As the high-frequency power supply 84, a power supply having a frequency of 400 kHz to 13.56 MHz is used.

  The electronic matching network 100 has a capacitor 101 and two coils 102 and 104, like the ordinary matching network, but the two coils 102 and 104 electrically apply the magnetic field from the induction coils 103 and 105, respectively. , The reactance is variable, and there is no mechanical movable part as in a normal matching network. Therefore, following the plasma is extremely fast, and a steady state can be achieved in about 0.5 sec, which is about 1/10 of the time of a normal matching network. Therefore, it is suitable for the case where the gas is alternately supplied while forming the plasma as described later.

  A circular hole 85 is formed in the center of the bottom wall 51b of the chamber 51. An exhaust chamber 86 protruding downward is provided on the bottom wall 51b so as to cover the hole 85. An exhaust pipe 87 is connected to a 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 pressure in the chamber 51 can be reduced to a predetermined degree of vacuum.

  The susceptor 52 is provided with three (only two of them are shown) wafer support pins 89 for supporting and raising and lowering the wafer W so as to be able to protrude and retract from the surface of the susceptor 52. It is fixed to the plate 90. Then, the wafer support pins 89 are moved up and down via a support plate 90 by a driving 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 from / to the wafer transfer chamber 1 and a gate valve G for opening / closing the loading / unloading port 92 are provided.

Next, a method of forming a Ti film using such an apparatus will be described.
First, the chamber 51 is evacuated to a pressure of 667 Pa, the susceptor 52 is heated to 350 to 700 ° C. by the heater 55, and the shower head 60 is heated to 450 ° C. or higher, for example, about 470 to 490 ° C. by the heater 96. I 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 to the shower head 60 from the high frequency power supply 84. 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 the inner wall of the chamber 51 and members in the chamber such as the shower head 60 are precoated with a Ti film. At this time, the gas flow rates are 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), and Ar gas: 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, while maintaining the temperatures of the susceptor 52 and the shower head 60, the gate valve G is opened and the wafer W is transferred from the wafer transfer chamber 1 in a vacuum state by the blade 14a or 14b of the transfer device 12 through the transfer port 92. Is loaded into the chamber 51 and is placed on the wafer support pins 89 protruding from the susceptor 52. The blade 14a or 14b 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, the formation of the Ti film on the wafer W is started. In this case, conventionally, the showerhead 60 has no heater, and the showerhead 60 is indirectly heated by the susceptor 52, so that the temperature of 450 ° C. or more is ensured so that the Ti film precoated on the showerhead 60 does not peel off. Requires that the temperature of the susceptor 52 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 has been 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 is difficult to apply the conventional CVD-Ti film forming conditions. Application to a capacitor film, a Low-k film, and an Al film is also conceivable. However, in this case also, a film formation temperature of 500 ° C. or lower is required, and it has been difficult to apply 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 in this manner, so that 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 such as a NiSi or a Low-k film that needs to be formed at a low temperature lower than 500 ° C., the Ti film can be formed without causing film peeling. Therefore, a Ti film having low specific resistance and good film quality can be formed.

Actually, the difference between the set temperature of the susceptor and the specific resistance of the Ti film formed on the SiO ₂ film in the case where the temperature is controlled by heating by the heater 96 in the shower head 60 (450 ° C. or more) and the case where the temperature control is not performed. As a result of determining 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 more by the heater 96.

After the wafer W is placed on the susceptor 52 as described above, the actual Ti film formation is performed according to the first and second embodiments described below.
First, a first embodiment will be described.
In the first embodiment, the heater 55 and the heater 96 are maintained under the same conditions as in the pre-coating, and as shown in the timing chart of FIG. While supplying TiCl ₄ gas, Ar gas, and H ₂ gas 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, (First plasma) is generated, and the first step of maintaining the plasma for 4 to 8 seconds is performed. Next, only the TiCl ₄ gas is stopped, and the high-frequency power and 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 three times or more, for example, about 12 to 24 times. The switching of the gas at this time is performed by switching the valve by the controller 98. In addition, although the state of the plasma changes due to such switching of the gas, the electronic matching network 100 automatically changes the plasma impedance to the transmission line impedance in accordance with the change in the plasma based on a command from the controller 106. Because of the matching, a good plasma state is maintained. Thus, a Ti film having a predetermined thickness is formed. At this time, the gas flow rates are 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), and Ar gas: 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 with TiCl ₄ gas + Ar gas + H ₂ gas + plasma and the second step of performing reduction with 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 concentration of residual chlorine in the Ti film can be reduced. In particular, chlorine remains in the Ti film at a low temperature of 450 ° C. or less, but even at such a low temperature, the sequence of the present embodiment reduces the residual chlorine concentration. As a result, good film quality with low specific resistance can be obtained.

After the formation of the Ti film in this manner, a nitriding treatment is performed. In this nitriding process, after the supply of the high frequency power and the gas is stopped and the Ti film formation is completed, as shown in FIG. Ar gas, H ₂ gas, and NH ₃ gas are supplied from the supply source 73, the H ₂ gas supply source 74, the NH ₃ gas supply source 75, and the second Ar gas supply source 76, and the Ti film surface is formed by the plasma of these gases. Nitriding. The time for this processing is about 30 to 60 seconds. The gas flow rate at this time, _{H 2} gas: 1.5~4.5L / min (1500~4500sccm), Ar gas: 0.8~2.0L / min (800~2000sccm) about, NH ₃ gas : About 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 a nitriding treatment, it is possible to prevent deterioration of the Ti film due to oxidation or the like, and to improve adhesion to a TiN film to be formed next. However, this nitriding treatment is not essential.

  Next, a result of comparison between a case where a Ti film is actually formed based on such a first embodiment and a case where a Ti film is formed by a conventional method will be described. Here, the susceptor temperature was set to 500 ° C., and a Ti film having a thickness of 10 nm was formed on Si, and the specific resistance was measured. In the sample of the first embodiment, a cycle of the first step for 4 seconds and the second step for 4 seconds was repeated 16 times to obtain a Ti film. 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 effect of the residual chlorine, but the Ti film formed in the first embodiment was high. Has a specific resistance of 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 high-frequency power is first applied from the high-frequency power supply 84 to the shower head 60 as shown in the timing chart of FIG. While supplying TiCl ₄ gas, Ar gas, and H ₂ gas 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 is performed in which a gas plasma (first plasma) is generated and maintained for 4 to 8 seconds. 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, a second step of reduction / nitridation treatment 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 three times or more, for example, about 12 to 24 times. The switching of the gas at this time is performed by switching the valve by the controller 98. In addition, in response to such a change in the plasma state due to the gas switching, the electronic matching network 100 automatically and follows the change in the plasma to change the plasma impedance based on the command from the controller 106. Match the impedance. Thus, a Ti film having a predetermined thickness is formed. At this time, the gas flow rates are 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), and NH ₃ gas: 0 0.5 to 2.0 L / min (500 to 2000 sccm), Ar gas: about 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.

As described above, the first step of forming a film by using TiCl ₄ gas + Ar gas + H ₂ gas + plasma and the second step of performing reduction and nitriding by using NH ₃ gas + Ar gas + H ₂ gas + plasma are performed in a relatively short time. Since it is alternately performed a plurality of times, the reducing action of reducing TiCl ₄ is enhanced, and the Ti film can be effectively nitrided to prevent the Ti film from deteriorating, thereby reducing residues such as chlorine. And 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 less, but even at such a low temperature, the sequence of the present embodiment reduces the residual chlorine concentration. As a result, good film quality with low specific resistance can be obtained.

In this embodiment, the Ti / TiN film can be formed by controlling the amount of the NH ₃ gas in the second step and the time of the second step. That is, when either a small supply amount of the NH ₃ gas, or the time of the second step short, nitriding is auxiliary, the formed film will function as a Ti film, the supply amount of the NH ₃ gas When the number of steps is large or 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 formed. Such a laminated film can function as a Ti / TiN film, and the Ti / TiN film can be formed by one type of apparatus. In this case, the TiN film forming apparatus 4 is not necessary, or is auxiliary even if necessary.

  Next, a result of comparison between a case where a Ti film is actually formed based on such a second embodiment and a case where a Ti film is formed by a conventional method will be described. Here, the susceptor temperature was set to 500 ° C., and a Ti film having a thickness of 10 nm was formed on Si, and the specific resistance was measured. In the sample of the second embodiment, a cycle of the first step for 4 seconds and the second step for 4 seconds was repeated 16 times to obtain a Ti film. 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 was high. Was 130 μΩ · cm, and the specific resistance was remarkably reduced. However, in this case, since the time of the second step was long, it is considered that the TiN film was also slightly formed. Therefore, it is considered that the specific resistance of the sample according to the second embodiment included a small amount of reduction due to the formation of the TiN film.

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

The gas supply mechanism 110 includes a ClF ₃ gas supply source 111 for supplying a ClF ₃ gas as a cleaning gas, a TiCl ₄ gas supply source 112 for supplying a TiCl ₄ gas as a Ti-containing gas, and a first supply of an 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. Then, ClF ₃ ClF ₃ gas supply line 116 to the gas supply source 111, the TiCl ₄ gas supply line 117 to the TiCl ₄ gas supply source 112, the first _{N 2} gas supply source 113 first _{N 2} A gas supply line 118 is connected to the NH ₃ gas supply source 114, and an NH ₃ gas supply line 119 is connected to the NH ₃ gas supply source 115, and a 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 a mass flow controller 122 and two valves 121 with the mass flow controller 122 interposed therebetween.

The 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 extends from the ClF ₃ gas supply source 111 to the TiCl ₄ gas supply line 117. 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, the second gas inlet port 62 and the NH ₃ gas supply line 119 extending from the NH ₃ gas supply source 114 is connected to the NH ₃ gas supply line 119, a second _{N 2} gas supply source 115 A second N ₂ gas supply line 120 extending from the second N ₂ gas supply line 120 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 The N ₂ gas from the _two- gas supply source 115 and the NH ₃ gas supply line 119 pass through the second gas inlet 62 of the shower head 60 to the inside of the shower head 60, and pass through the gas passages 64 and 66 from the discharge hole 68. It is discharged into the chamber 51. That is, the shower head 60 is of a matrix type in which the TiCl ₄ gas and the NH ₃ gas are supplied into the chamber 51 completely independently, and these are mixed after ejection to cause a reaction. The valve 121 and the mass flow controller 122 are controlled by the controller 123.

Next, a method of forming a TiN film using such an apparatus will be described.
First, the inside of the chamber 51 is cut off by the exhaust device 88, and N ₂ gas is introduced into the chamber 51 through the shower head 60 from the first and second N ₂ gas supply sources 113 and 115, and the heater 55. Preheats the inside of 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, NH ₃ gas supply source 114, and TiCl ₄ gas supply source 112 via the shower head 60. The preflow is performed at a predetermined flow rate while maintaining the pressure in the chamber at a predetermined value. Then, while maintaining the same gas flow rate and pressure, the TiN film is pre-coated on the inner wall of the chamber 51, the inner wall of the exhaust chamber 86, and the surfaces of the members in the chamber such as the shower head 60 by heating with the heater 55.

After precoating process is finished, NH ₃ gas and TiCl ₄ gas is stopped, first and second _{N 2} gas supply source 113 and 115 from the _{N 2} gas purge in the chamber 51 is supplied to the chamber 51 as a purge gas Then, 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 interior of the chamber 51 is rapidly evacuated by the exhaust device 88 to a cut-off state, the gate valve G is opened, and the wafer W is transferred from the wafer transfer chamber 1 in the vacuum state by the wafer transfer device 12 through the loading / unloading port 92. Is carried into the chamber 51. Then, N ₂ gas is supplied into the chamber 51 to preheat the wafer W. When the temperature of the wafer is substantially stabilized, the formation of the TiN film is started.

The formation of the TiN film is performed according to 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 the pre-flow of the TiCl ₄ gas is performed while maintaining the pressure in the chamber at a predetermined value. Then, while keeping the gas flow rate and the pressure in the chamber 51 the same, a TiCl ₄ gas is introduced into the chamber. 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. Thus, a Ti film having a predetermined thickness is formed by flowing the N ₂ gas, the NH ₃ gas, and the TiCl ₄ gas for a predetermined time. At this time, the gas flow rates are 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 2,000 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 10000 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 the TiCl ₄ gas are stopped, and the N ₂ gas is supplied as a purge gas from the purge gas line (not shown) at a flow rate of preferably 0.5 to 10 L / min to purge the chamber 51. Then, an N ₂ gas and an NH ₃ gas are flowed, and the surface of the TiN thin film formed on the wafer W is nitrided. At this time, the supply of the N ₂ gas is performed from one or both of the first and second N ₂ gas supply sources 113 and 115. In addition, this nitride processing is not essential.

After a lapse of a predetermined time, the N ₂ gas and the NH ₃ gas are gradually stopped, and when the supply of these gases is completely stopped, the film forming process is ended.

Next, a second embodiment of TiN film formation will be described. The temperature of the wafer W by the heater 55 is maintained at approximately the same 400 to 700 ° C., as shown in the timing chart of FIG. 11, the first, TiCl ₄ gas supply source 112, NH ₃ gas supply source 114, TiCl ₄ The first step of forming a TiN film by thermal CVD by supplying a gas and an NH ₃ gas to the chamber 51 by carrying the N ₂ gas from the first and second N ₂ gas supply sources 113 and 115 as carriers. Perform for 2-8 seconds. Next, the TiCl ₄ gas and the NH ₃ gas are stopped, an N ₂ gas is introduced as a purge gas into the chamber 51 from a purge gas line (not shown), and the purge in the chamber 51 is performed 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, an 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 plural cycles, preferably three or more cycles, for example, about 12 to 24 times. The switching of the gas at this time is performed by switching the valve by the controller 123.

  By performing such an alternate gas flow, the TiN film formed in the first step is efficiently dechlorinated by the annealing in the second step, and the residual chlorine in the film can be significantly reduced. A high quality TiN film with little residual chlorine can be formed even at a low temperature.

  In any case of forming the above-described TiN film, the underlying Ti film is formed by the process using the alternating gas flow shown in the first embodiment or the second embodiment as described above. Therefore, it is possible to make a state in which film peeling between the Ti film and the TiN film hardly occurs, and the film quality of the whole Ti / TiN film becomes better than before. When a Ti film is formed by a conventional gas flow, film peeling between the Ti film and the TiN film frequently occurs regardless of the method of forming the TiN film.

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

  As a result, in the case where the Ti film was formed under the above conditions in the range of the first and second embodiments, no visual peeling and discoloration were observed even when the TiN film was formed by any method. It was confirmed that no film peeling occurred. On the other hand, when the Ti film was formed by the conventional method, peeling and discoloration were confirmed regardless of the method of forming the TiN film. Further, it was confirmed that the Ti / TiN film sample in which the Ti film was formed under the above conditions in the first and second embodiments had lower electric resistance and better film quality than the conventional one. .

Next, a method of forming a Ti / TiN film using only the Ti film forming apparatus 3 without using the TiN film forming apparatus 4 will be described with reference to FIG.
Here, maintaining the heater 55 and the heater 96 to the same conditions as during the pre-coating, as shown in the timing chart of FIG. 12, first, while applying the high frequency power from the high frequency power source 84 to the showerhead 60, TiCl ₄ A TiCl ₄ gas, an Ar gas, and an H ₂ gas are supplied from a gas supply source 72, a first Ar gas supply source 73, an H ₂ gas supply source 74, and a second Ar gas supply source 76, and plasma of these gases (first The first step is to generate and maintain this plasma for 4 to 8 seconds. Next, only the TiCl ₄ gas is stopped, and the high-frequency power and 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 three times or more, for example, about 12 to 24 times, to first form a Ti film. At this time, the gas flow rates are 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), and Ar gas: 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 formation of the Ti film in this manner, the formation of the TiN film is subsequently performed. After the supply of high frequency power and gas is stopped and the Ti film is formed, the susceptor 52 is heated to 450 to 550 ° C. by the heater 55 and the shower head 60 is heated to 450 ° C. by the heater 96. Heat to the above temperature, for example, about 470 to 490 ° C. 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 (third plasma) of these gases and maintaining the plasma 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, a fourth step, which is a reduction / nitriding 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 are 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), and NH ₃ gas: 0 0.5 to 1.5 L / min (500 to 1500 sccm), Ar gas: about 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 switching of the gas at this time is performed by switching the valve by the controller 98. In addition, in response to such a change in the plasma state due to the gas switching, the electronic matching network 100 automatically and follows the change in the plasma to change the plasma impedance based on the command from the controller 106. Match the impedance.

As described above, the first step of forming a film with TiCl ₄ gas + Ar gas + H ₂ gas + plasma and the second step of performing reduction with 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 by using TiCl ₄ gas + Ar gas + H ₂ gas + plasma; and a fourth step of performing reduction and nitridation with NH ₃ gas + Ar gas + H ₂ gas + plasma. Is performed alternately a plurality of times in a relatively short time to form a TiN film, so that the reducing action for reducing the Ti compound is enhanced, and nitriding can be performed effectively. Therefore, the concentration of residual chlorine in the Ti film can be reduced. In particular, when the wafer temperature is lower than 450 ° C., chlorine remains in the Ti film or the TiN film more. Even at such a low temperature, the residual chlorine concentration can be increased by using the sequence of the present embodiment. And a Ti / TiN laminated structure with low resistivity and good film quality can be obtained. Further, since a Ti / TiN laminated structure, which conventionally required two types of film forming apparatuses, can be continuously formed by 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 four 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 manner, the Ti / TiN film can be formed by one type of film forming apparatus. Therefore, when this method is used, the TiN film forming apparatus 4 is unnecessary.

Note that 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 is described in the above embodiment, the present invention is not limited to this, and is effective for other films formed by plasma CVD. Further, 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, but may be a mixed gas of N ₂ and H ₂ . 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, an effective reduction can be performed, a film can be formed at a lower temperature, and a residue in the film can be reduced, and a film having better film quality can be formed. Therefore, it is suitable for a film forming use on a material having low heat resistance such as NiSi or a capacitor film.

FIG. 1 is a schematic configuration diagram showing a multi-chamber type film forming system equipped with a Ti film film forming apparatus for implementing an embodiment of a film forming method of the present invention. FIG. 4 is a cross-sectional view showing a via hole portion of a semiconductor device having a Ti / TiN film formed thereon. FIG. 2 is a sectional view showing a pre-cleaning device mounted on the film forming system of FIG. 1. FIG. 2 is a cross-sectional view showing a Ti film forming apparatus used for carrying out the present invention, which is mounted on the film forming system of FIG. 1. 5 is a graph showing the relationship between the susceptor temperature during film formation and the specific resistance value of a Ti film with and without the temperature control of the showerhead. 5 is a timing chart showing the timing of gas supply and high-frequency power supply according to the first embodiment of the Ti film forming method. 4 is a graph showing an effect of the first embodiment of the Ti film forming method. 9 is a timing chart showing the timing of gas supply and high-frequency power supply according to a second embodiment of the Ti film forming method. 9 is a graph showing the effect of the second embodiment of the Ti film forming method. FIG. 2 is a cross-sectional view showing a TiN film forming apparatus mounted on the film forming system of FIG. 1. 6 is a timing chart showing a gas supply timing according to a second embodiment of the TiN film forming method. 4 is a timing chart showing the timing of gas supply and high-frequency power supply when Ti / TiN is formed by the same apparatus according to the present invention.

Explanation of reference numerals

2 Pre-cleaning device 3 Ti film forming device 4 TiN film forming device 51 Chamber 52 Susceptors 55 and 96 Heater 60 Shower head 70 Gas supply mechanism 98 Controller 100: Electronic matching type matching network W: Semiconductor wafer

Claims (11)

In the processing chamber, a compound gas containing a component of the film to be formed on the substrate to be processed and a reducing gas are supplied, and plasma is generated in the chamber to form a thin film on the substrate by CVD. The method,
A first step of generating a first plasma while introducing the compound gas and the reducing gas, and a second step of generating a second plasma while stopping the compound gas and introducing the reducing gas are alternately performed. The film forming method according to claim 1, wherein the first plasma and the second plasma are switched so as to follow the alternate gas switching.   The film forming method according to claim 1, wherein the second step introduces a nitriding gas in addition to the reducing gas.   2. The method according to claim 1, wherein after performing the first step and the second step a plurality of times, a nitriding treatment is performed by generating a third plasma while introducing the reducing gas and the nitriding gas. 3. Film formation method. A film forming method for forming a Ti film on a substrate to be processed by CVD in a processing chamber,
A first step of generating the first plasma while introducing the Ti compound gas and the reducing gas and a second step of generating the second plasma while stopping the Ti compound gas and introducing the reducing gas are alternately performed in plural numbers. The film forming method according to claim 1, wherein the first plasma and the second plasma are switched so as to follow the alternate gas switching.   After repeating the first step and the second step a plurality of times, performing a nitriding treatment for generating a third plasma while introducing the reducing gas and a gas containing N and H. 5. The film forming method according to item 4. A film forming method for forming a Ti or Ti / TiN film on a substrate to be processed in a processing chamber by CVD,
A first step of generating a first plasma while introducing a Ti compound gas and a reducing gas, and generating a second plasma while stopping the Ti compound gas and introducing a gas containing the reducing gas and N and H; The film forming method according to claim 1, wherein the second step is alternately repeated a plurality of times, and the first plasma and the second plasma are switched so as to follow the alternate gas switching. The use of a TiCl ₄ gas as a Ti compound gas, the film forming method according to any one of claims 6 claim 4, characterized by using H ₂ gas as the reducing gas. 7. The film forming method according to claim 5, wherein the gas containing N and H is NH ₃ gas.   The temperature of the to-be-processed substrate is set at 300-700 degreeC during the process in the state which the said to-be-processed board | substrate is mounted on a mounting table, The Claims 1-8 characterized by the above-mentioned. Film formation method.   The film forming method according to any one of claims 4 to 9, wherein a natural oxide film on the surface of the underlayer is removed before forming the Ti film. The plasma is generated by supplying high-frequency power to at least one of a pair of parallel plate electrodes, and matching between plasma impedance and transmission line impedance is performed by an electronic matching type matching network. Item 11. The film forming method according to any one of items 10.

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