JP4451097B2 - Deposition method - Google Patents

Deposition method Download PDF

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JP4451097B2
JP4451097B2 JP2003291667A JP2003291667A JP4451097B2 JP 4451097 B2 JP4451097 B2 JP 4451097B2 JP 2003291667 A JP2003291667 A JP 2003291667A JP 2003291667 A JP2003291667 A JP 2003291667A JP 4451097 B2 JP4451097 B2 JP 4451097B2
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film
plasma
si
metal
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JP2004158828A (en
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健索 成嶋
誠志 村上
雅人 森嶋
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東京エレクトロン株式会社
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  The present invention relates to a film forming method for forming a metal silicide film on a target object, for example, a Si-containing portion such as a surface of a Si substrate or a metal silicide layer by plasma treatment.

  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 device 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 contact holes and via holes. 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.

These films can be formed by chemical vapor deposition (which can form a high-quality film without increasing the electrical resistance even when the device is miniaturized and highly integrated, and can improve the step coverage. CVD) is used. Then, by forming a Ti film by CVD using TiCl 4 as a raw material, it reacts with the underlying Si to selectively grow TiSi 2 in a self-aligned manner on the Si diffusion layer at the bottom of the contact hole, thereby providing good ohmic resistance. (For example, Patent Document 1).

When a CVD-Ti film is formed, TiCl 4 gas is generally used as a source gas as described above, and H 2 gas or the like is used as a reducing gas. However, the binding energy of this TiCl 4 gas is considerably high. Since the thermal energy alone is not decomposed unless it is a high temperature of about 1200 ° C., the film is usually formed at a process temperature of about 650 ° C. by plasma CVD using plasma energy together.

  On the other hand, in such metal film formation, in order to obtain good contact resistance, a process of removing a natural oxide film formed on the base is performed prior to the film formation process. The removal of such a natural oxide film has generally been performed with dilute hydrofluoric acid. However, as an apparatus for removing the natural oxide film, inductively coupled plasma is formed using hydrogen gas and argon gas as shown in Patent Document 2. What to do has been proposed.

However, as miniaturization of the device is further proceeds, for example, shallower depth of the Si diffusion layer, that in the conventional Ti-CVD method using TiSi 2 film obtain the required contact resistance is becoming difficult.

In order to lower the contact resistance is by increasing forming TiSi 2 in a lower C54 crystal structure resistance is effective to reduce the resistance of the TiSi 2 film itself, the process temperature to a high temperature in the conventional Ti-CVD method Therefore, it was difficult to form a TiSi 2 film having a large amount of TiSi 2 having a C54 crystal structure.

Further, as described above, when a Ti film is formed by a conventional plasma CVD method, TiSi 2 crystals having a nonuniform particle size tend to be formed. In particular, when the natural oxide film is removed by argon plasma prior to the formation of the TiSi 2 film, the surface of the Si diffusion layer is damaged and becomes non-uniformly amorphous, and in this state, the Ti film is formed by plasma CVD. When the film is formed, the formed TiSi 2 crystal becomes more non-uniform. Then, due to the presence in such a relatively sparse TiSi 2 crystals uneven state, the high resistivity contact between TiSi 2 film and the base becomes non-uniform. Accordingly, the contact resistance increases.

On the other hand, as described above, when the depth of the Si diffusion layer is reduced as the device is miniaturized, the TiSi 2 film at the bottom of the contact hole is also thinned, and the morphology of the interface between the Si diffusion layer and the TiSi 2 film is good. Something has come to be required. However, in the conventional Ti-CVD method, since the grain size of the TiSi 2 crystal is large and non-uniform, it is difficult to obtain a sufficient interface morphology.
JP-A-5-67585 (Claim 1, FIG. 1 and its description). Japanese Patent Laid-Open No. 4-336426 (FIG. 2 and its explanation).

  The present invention has been made in view of such circumstances, and in the case where a metal silicide film such as a titanium silicide film is formed on a Si-containing portion of an object to be processed, the conventional technique does not increase the film formation temperature. Another object of the present invention is to provide a film forming method capable of forming a low-resistance metal silicide film. It is another object of the present invention to provide a film forming method capable of forming a metal silicide film having a uniform crystal grain size, particularly a titanium silicide film. It is another object of the present invention to provide a film forming method capable of forming a metal silicide film, particularly a titanium silicide film, having fine and uniform crystal grains and good interface morphology.

In order to solve the above problems, according to a first aspect of the present invention, there is provided a film forming method for forming a metal silicide film on a Si-containing portion of an object to be processed. as gas use, Ar, Ne, He, or Ar, and treating Ne, combined with any of He and H 2, or Ar, Ne, by plasma using combined gas and either the NF 3 of He Supplying a metal-containing source gas containing a metal in the metal silicide to be formed on the Si-containing portion that has been treated with the plasma, and generating a plasma to form a metal film made of the metal And a step of forming a metal silicide film by a reaction between the metal film at that time and Si in the Si-containing portion, and the treatment of the Si-containing portion with plasma has an absolute value of 200 V or more on the object to be processed. While applying a C bias voltage (Vdc) have rows, the step of forming the metal silicide film, a metal-containing raw material gas is supplied for a predetermined time metal without first generating a plasma - causing silicon bonds, then There is provided a film forming method characterized by generating plasma .

  As described above, in the plasma processing using the high frequency of the Si-containing layer performed prior to the film formation, by applying a DC bias voltage (Vdc) having an absolute value as high as 200 V or more to the target object, the target object is processed. The ions in the plasma act on the surface more strongly than in the case of conventional natural oxide film removal. For this reason, the Si-containing layer of the film formation base is entirely amorphized to form a highly reactive state (in the case of Si, a surface state with more unbonded Si than Si single crystal), and resistance In the case where the metal silicide crystal having a low crystal structure, for example, the metal is titanium, more titanium silicide having a C54 crystal structure can be present at a lower processing temperature than in the prior art. Accordingly, it is possible to form a metal silicide film having a lower thickness and lower resistance than before without increasing the film formation temperature, and as a result, the contact resistance can be lowered. Furthermore, even when film formation is performed at a lower temperature of the object to be processed than before, a crystalline metal silicide film similar to the conventional one can be obtained.

  In the first aspect, examples of the Si-containing portion include a Si substrate, poly-Si, and metal silicide, and a contact diffusion layer formed on a single crystal Si substrate (Si wafer) is a typical example. it can. Si substrates include those doped with B, P, As or the like. The treatment of the Si-containing portion with plasma can be performed using inductively coupled plasma. Alternatively, parallel plate plasma or microwave plasma can be used. Further, the step of forming the metal silicide film may repeat the supply of the metal-containing source gas and the reduction of the metal-containing source gas by supplying plasma and a reducing gas a plurality of times. Thereby, the film can be formed at a lower temperature. Furthermore, examples of the metal include Ni, Co, Pt, Mo, Ta, Hf, and Zr in addition to Ti described above. These metals are usually capable of forming a metal silicide crystal structure having low resistance at high temperatures.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Here, a case where a titanium silicide film is formed on a Si wafer using a Ti-containing source gas as a metal-containing source gas will be described as an example.
FIG. 1 is a process diagram for explaining a film forming method according to the first embodiment of the present invention.

In the first embodiment, first, as shown in FIG. 1A, an interlayer insulating film 2 is formed on a Si wafer 1, and a contact hole 3 reaching the surface of the Si wafer 1 is formed by etching. Next, as shown in FIG. 1B, the surface of the Si wafer 1 is treated with plasma using a high frequency while applying a DC bias voltage having an absolute value of 200 V or more to the Si wafer 1. Subsequently, as shown in FIG. 1C, a Ti-containing source gas such as TiCl 4 is supplied to the Si wafer 1 to generate plasma to form a Ti film. reaction by forming the TiSi 2 film 4. Then, if necessary, as shown in FIG. 1 (d), as a pretreatment to the formation of the next TiN film, subjected to a nitriding treatment to the surface of the TiSi 2 film 4 with NH 3.

Next, an apparatus for performing the plasma processing of FIG. 1B, which is a main process of the present embodiment, and an apparatus for forming the TiSi 2 film of FIG. 1C will be described.

  FIG. 2 is a cross-sectional view showing a schematic configuration of a plasma processing apparatus that performs the process of FIG. This apparatus is an inductively coupled plasma (ICP) system, and is basically for removing a natural oxide film. In the first embodiment, not only the removal of the natural oxide film but also an RF bias is applied to the Si wafer 1. Is applied to attract ions to the surface of the Si wafer 1 to perform treatment with ions.

  A plasma processing apparatus 10 that performs plasma processing using the high frequency includes a substantially cylindrical chamber 11 and a substantially cylindrical bell jar 12 that is provided continuously above the chamber 11 in the chamber 11. In the chamber 11, a susceptor 13 made of ceramics such as AlN for horizontally supporting the Si wafer 1 as an object to be processed is arranged in a state supported by a cylindrical support member 14. A clamp ring 15 that clamps the Si wafer 1 is provided on the outer edge of the susceptor 13. Further, a heater 16 for heating the Si wafer 1 is embedded in the susceptor 13, and the heater 16 is supplied with power from a heater power supply 25 to heat the Si wafer 1 as an object to be processed to a predetermined temperature. To do.

  The bell jar 12 is made of an electrically insulating material such as quartz or a ceramic material, and a coil 17 serving as an antenna member is wound around the bell jar 12. A high frequency power source 18 is connected to the coil 17. The high frequency power source 18 has a frequency of 300 kHz to 60 MHz, preferably 450 kHz. An induction electromagnetic field is formed in the bell jar 12 by supplying high frequency power from the high frequency power supply 18 to the coil 17.

  The gas supply mechanism 20 is for introducing a gas for plasma processing into the chamber 11. The gas supply mechanism 20 is used to supply a predetermined gas supply source, piping from each gas supply source, an open / close valve, and a flow rate control. It has a mass flow controller (both not shown). A gas introduction nozzle 27 is provided on the side wall of the chamber 11, a pipe 21 extending from the gas supply mechanism 20 is connected to the gas introduction nozzle 27, and a predetermined gas passes through the gas introduction nozzle 27. Introduced in. Note that the valves and the mass flow controller of each pipe are controlled by a controller (not shown).

Examples of the plasma 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 28 is connected to the bottom wall of the chamber 11, and an exhaust device 29 including a vacuum pump is connected to the exhaust pipe 28. Then, by operating the exhaust device 29, the inside of the chamber 11 and the bell jar 12 can be depressurized to a predetermined degree of vacuum.

  Further, a gate valve 30 is provided on the side wall of the chamber 11, and the wafer W is transferred between adjacent load lock chambers (not shown) with the gate valve 30 opened. ing.

  Further, in the susceptor 13, for example, an electrode 32 formed by weaving tungsten, molybdenum wire or the like in a mesh shape is embedded, and a high frequency power source 31 is connected to the electrode 32 to apply a negative DC bias. Is possible.

When performing the above-described plasma processing in the apparatus configured as described above, the gate valve 30 is opened, the wafer W is loaded into the chamber 11, the Si wafer W is placed on the susceptor 13, and the clamp ring 15 is used. Clamp. Thereafter, the gate valve 30 is closed, and the inside of the chamber 11 and the bell jar 12 is exhausted by the exhaust device 29 to be in a predetermined reduced pressure state. Subsequently, a predetermined gas is introduced into the chamber 11 from the gas supply mechanism 20 through the gas introduction nozzle 27. For example, plasma is generated by introducing high-frequency power from the high-frequency power source 18 to the coil 17 to form an induction electromagnetic field in the bell jar 12 while introducing Ar gas or Ar gas and H 2 gas. On the other hand, high frequency power is supplied from the high frequency power supply 31 to the susceptor 13, and a negative bias voltage, that is, a DC bias voltage (Vdc) is applied to the Si wafer 1. By applying this Vdc, ions in the plasma are drawn into the Si wafer 1. In the present embodiment, the power of the high frequency power supplies 18 and 31 is adjusted so that the absolute value of Vdc at this time is 200 V or more. For example, by applying 500 W to the high-frequency power source 18 and 800 W to the high-frequency power source 31, Vdc = −530V. Incidentally, Vdc at the time of normal oxide film removal is about −100 to −180V. In the present embodiment, a higher Vdc is applied than in the case of normal natural oxide film removal. By increasing Vdc in this way, ions in the plasma act on the surface of the Si wafer 1 more strongly than in the case of conventional natural oxide film removal. Therefore, the overall amorphous surface of the Si wafer 1 as a film-forming base becomes highly reactive state, when forming a subsequent TiSi 2 film as described later, that the contact resistance is lower They can be formed much TiSi 2 crystal structure C54. The absolute value of Vdc is preferably 250V, and more preferably 300V or more.

The processing conditions at this time are, for example, a pressure of 0.01 to 13.3 Pa, preferably 0.04 to 2.7 Pa, a wafer temperature of room temperature to 500 ° C., and gas flow rates of Ar and H 2 : 0.001 to 0 The frequency of the high frequency power supply 18 for ICP is 450 kHz, the power is 200 to 1500 W, the frequency of the high frequency power supply 31 for bias is 13.56 MHz, and the power is 100 to 1000 W.

Next, a Ti film forming apparatus that performs the subsequent process of forming the TiSi 2 film of FIG. 1C will be described.
FIG. 3 is a cross-sectional view showing a schematic configuration of the Ti film forming apparatus. This film forming apparatus 40 has a substantially cylindrical chamber 41 that is hermetically configured, and a susceptor 42 for horizontally supporting the Si wafer 1 that is an object to be processed is cylindrically supported therein. It is arranged in a state where it is supported by the member 43. The susceptor 42 is made of ceramics such as AlN. A guide ring 44 for guiding the Si wafer W is provided on the outer edge of the susceptor 42. The guide ring 44 also has a plasma focusing effect. In addition, a resistance heating type heater 45 made of molybdenum, tungsten wire, or the like is embedded in the susceptor 42, and the heater 45 is supplied with power from a heater power supply 46 so that the Si wafer 1 as an object to be processed has a predetermined temperature. Heat to. In addition, the delivery of the Si wafer 1 to the susceptor 42 is performed in a state where the Si wafer 1 is lifted by three lift pins provided so as to be freely projecting and retracting therein.

  A shower head 50 is provided on the top wall 41 a of the chamber 41 via an insulating member 49. The shower head 50 includes an upper block body 50a, an intermediate block body 50b, and a lower block body 50c. Discharge holes 57 and 58 for discharging gas are alternately formed in the lower block body 50c. A first gas inlet 51 and a second gas inlet 52 are formed on the upper surface of the upper block body 50a. In the upper block body 50 a, a large number of gas passages 53 are branched from the first gas introduction port 51. Gas passages 55 are formed in the middle block body 50 b, and the gas passages 53 communicate with these gas passages 55. Further, the gas passage 55 communicates with the discharge hole 57 of the lower block body 50c. In the upper block body 50a, a large number of gas passages 54 are branched from the second gas introduction port 52. Gas passages 56 are formed in the middle block body 50 b, and the gas passages 54 communicate with the gas passages 56. Further, the gas passage 56 communicates with the discharge hole 58 of the lower block body 50c. The first and second gas inlets 51 and 52 are connected to a gas line of the gas supply mechanism 60.

Gas supply mechanism 60 supplies a cleaning gas supplying ClF 3 gas is ClF 3 gas supply source 61, Ti-containing TiCl 4 gas TiCl 4 gas supply source 62 for supplying a gas, Ar gas is a plasma gas Ar gas supply source 63, a NH 3 gas supply source 71 for supplying H 2 gas to supply H 2 gas supply source 64, an NH 3 gas as a reducing gas. Then, ClF 3 gas line 65 to a gas supply source 61, a gas line 66 to the TiCl 4 gas supply source 62, a gas line 67 in an Ar gas supply source 63, H 2 gas supply source 64 gas in line 68, and a gas line 79 is connected to the NH 3 gas supply source 71, respectively. Each line is provided with a valve 69, a valve 77, and a mass flow controller 70. A gas line 80 connected to an exhaust device 76 is connected to a gas line 66 extending from the TiCl 4 gas supply source 62 via a valve 78. Yes. A gas line 66 extending from a TiCl 4 gas supply source 62 is connected to the first gas inlet 51, and a gas line 65 extending from a ClF 3 gas supply source 61 and an Ar gas supply source 63 are connected to the gas line 66. A gas line 67 extending from is connected. A gas line 68 extending from the H 2 gas supply source 64 and a gas line 79 extending from the NH 3 gas supply source 71 are connected to the second gas introduction port 52. Therefore, when the process reaches the first gas inlet port 51 of the shower head 50 through the TiCl 4 gas is a carrier of Ar gas gas line 66 from the TiCl 4 gas supply source 62 to the showerhead 50, the gas passage The H 2 gas from the H 2 gas supply source 64 is discharged from the second gas introduction port 52 of the shower head 50 through the gas line 68 while being discharged into the chamber 41 from the discharge hole 57 through 53 and 55. 50 is discharged from the discharge hole 58 into the chamber 41 through the gas passages 54 and 56. That is, the shower head 50 is a post-mix type in which TiCl 4 gas and H 2 gas are supplied into the chamber 41 completely independently, and these are mixed and reacted after discharge. The valves and mass flow controllers of each gas line are controlled by a controller (not shown).

  A high frequency power source 73 is connected to the shower head 50 via a matching unit 72. When the high frequency power is supplied from the high frequency power source 73 to the shower head 50, the shower head 50 is supplied into the chamber 41 via the shower head 50. The formed gas is turned into plasma, whereby the film formation reaction proceeds. As a counter electrode of the shower head 50 that functions as an electrode to which high-frequency power is supplied, an electrode 74 formed by weaving, for example, a molybdenum wire or the like in a mesh shape is embedded above the susceptor 42. A high-frequency power source 82 is connected to the electrode 74 via a matching unit 81 so that a high-frequency voltage for obtaining a bias voltage is applied.

  An exhaust pipe 75 is connected to the bottom wall 41 b of the chamber 41, and an exhaust device 76 including a vacuum pump is connected to the exhaust pipe 75. By operating the exhaust device 76, the inside of the chamber 41 can be depressurized to a predetermined degree of vacuum.

Next, a Ti film forming process in the Ti film forming apparatus will be described.
First, while the chamber 41 is heated to 500 to 700 ° C. by the heater 45, the chamber 41 is evacuated by the exhaust device 76 to a predetermined vacuum state, and Ar gas and H 2 gas are supplied at a predetermined flow ratio, for example, Ar gas. Is introduced into the chamber 41 at a rate of 0.1 to 5 L / min and H 2 gas at a rate of 0.5 to 10 L / min, and high frequency power is supplied from the high frequency power source 73 to the shower head 50 to generate plasma in the chamber 41. is allowed, the further predetermined flow rate TiCl 4 gas, performs pre-coating process of the Ti film in the chamber 41 is supplied, for example 0.001~0.05L / min. Then, stop the TiCl 4 gas, is introduced into the chamber 41 the NH 3 gas, for example in 0.1~3L / min, is stabilized by nitriding the precoat Ti film to generate plasma.

Next, the gate valve (not shown) is opened, the Si wafer 1 is loaded into the chamber 41 from a load lock chamber (not shown), the Si wafer 1 is placed on the susceptor 42, and the chamber 41 is exhausted by the exhaust device 76. While heating the wafer W with the heater 45, the H 2 gas is 0.5 to 10.0 L / min, preferably 0.5 to 5.0 L / min, the Ar gas is 0.1 to 5.0 L / min, Preferably, the gas is introduced into the chamber 41 at a flow rate of 0.3 to 2.0 L / min. Next, while maintaining the Ar gas and H 2 gas, the inside of the chamber 41 is set to 40 to 1333 Pa, preferably 133.3 to 666.5 Pa. While maintaining these flow rates, after pre-flowing by introducing TiCl 4 gas into the chamber 41 at a flow rate of 0.001 to 0.05 L / min, preferably 0.001 to 0.02 L / min, the heater The heating temperature (susceptor temperature) of the Si wafer 1 by 45 is maintained at about 500 to 700 ° C., preferably about 600 ° C., and the frequency of 300 kHz to 60 MHz, preferably 400 to 450 kHz, from the high frequency power source 73 to the shower head 50, A high frequency power of 200 to 1000 W, preferably 200 to 500 W, is supplied to generate plasma in the chamber 41, and a Ti film is formed in a plasma gas.

At the same time as the Ti film is deposited in this way, this Ti film sucks up Si from the underlying Si wafer 1 and a TiSi 2 film is formed by the reaction between Ti and Si. In this case, as described above, an absolute value of 200 V is applied to the surface of the Si wafer 1, which is much higher than that in the case of conventional natural oxide film removal. Not only is removed, but ions in the plasma act more strongly on the surface of the Si wafer 1, and the surface of the Si wafer 1 as a base for film formation becomes amorphous as a whole. There are many broken portions), and a highly reactive state is formed. As a result, a large amount of titanium silicide having a C54 crystal structure with low resistance can be present at a lower wafer temperature than in the prior art. Therefore, it is possible to form a titanium silicide film having a lower thickness and lower resistance than before without increasing the film formation temperature, and as a result, the contact resistance can be lowered.

Further, since the surface of the underlying Si wafer 1 is in such a highly reactive state, the temperature for forming the same film as the conventional TiSi 2 film can be lowered by about 50 to 100 ° C.

The Ti film may be formed by supplying TiCl 4 gas, supplying H 2 gas, and generating plasma simultaneously as described above. First, TiCl 4 gas is supplied for a short time to form the Ti film. after that caused the adsorption reaction (reaction between Ti and Si), a step of forming a Ti film with TiCl 4 gas and H 2 gas and Ar gas and plasma generation, the introduction + plasma generation of H 2 gas and Ar gas It can also be performed by a process in which the steps to be performed are repeated a plurality of times, for example, an ALD (Atomic Layered Deposition) process. As a result, the film formation temperature can be further lowered, and film formation can be performed at 500 ° C. or less, for example, about 350 ° C. Further, in the formation of the Ti film, causing Ti-Si bonds on the Si wafer of the TiCl 4 gas before the plasma generation is supplied a predetermined time, and then it may generate the plasma. Thereby, the resistance of the titanium silicide film can be further reduced.

Thereafter, nitriding treatment of the surface of the TiSi 2 film 4 is performed as necessary. In this case, the temperature of the susceptor 42 is set to about 350 to 700 ° C., preferably 600 ° C., and the inside of the chamber 41 of the apparatus of FIG. The NH 3 gas can be supplied from the NH 3 gas supply source 71 at a flow rate of, for example, 0.1 to 3 L / min together with Ar gas and H 2 gas, and plasma can be generated by applying a high frequency. The pressure in the chamber 41, temperature, plasma generation conditions, Ar gas flow rate, H 2 gas flow rate, and the like during nitriding are the same as those during Ti film formation.

After forming a predetermined number of the way, to supply ClF 3 gas from ClF 3 gas supply source 61 into the chamber 41, for cleaning the chamber.

Next, a second embodiment of the present invention will be described.
In the second embodiment, as shown in FIG. 4 (a), the same processing as in FIG. 1 (a) is performed, and then, as shown in FIG. 4 (b), plasma using high frequency is used. Thus, the natural oxide film on the surface of the Si wafer 1 is removed. Subsequently, as shown in FIG. 4C, a Ti-containing source gas such as TiCl 4 gas is supplied to the Si wafer 1, plasma is generated to form a Ti film, and the Ti film and the Si wafer 1 are formed. The TiSi 2 film 4 is formed by the reaction. This process is basically the same as in FIG. 1C, but here, H 2 gas and Ar gas are first supplied, and then a Ti-containing raw material such as TiCl 4 gas is generated without generating plasma. A gas is supplied for a predetermined time to generate a Ti-Si bond, and then a plasma is generated. Thereafter, as shown in FIG. 4D, the same processing as in FIG. 1D is performed as necessary, and the surface of the TiSi 2 film 4 is subjected to plasma nitriding.

  In the present embodiment, the process of removing the natural oxide film in FIG. 4B can be performed using an apparatus similar to the apparatus that implements FIG. 1B of the first embodiment. In this embodiment, since only the natural oxide film needs to be removed, the absolute value of Vdc of the Si wafer can be set to about 100 to 180 V, and the other conditions can be processed in the same manner as the above conditions. However, also in this embodiment, it is effective to perform the processing with the absolute value of Vdc being 200 V or more.

The film forming process for the TiSi 2 film shown in FIG. 4C is performed under basically the same film forming conditions by the apparatus shown in FIG. 3, but in this embodiment, no plasma is formed. TiCl 4 is supplied to the substrate, and then plasma is formed to perform processing. Specifically, after the Si wafer 1 is placed on the susceptor 42, the chamber 41 is evacuated by the exhaust device 76 while the wafer W is heated by the heater 45, and the chamber 41 is brought to the predetermined pressure. As shown in the timing, after introducing H 2 gas and Ar gas into the chamber 41 at the predetermined flow rate and performing preflow, TiCl 4 gas is allowed to flow at the predetermined flow rate for T seconds while maintaining these flow rates. Ti—Si bonds are generated on the Si wafer 1, and then the predetermined high frequency power is supplied from the high frequency power source 73 to generate plasma in the chamber 41, and the film forming process is continued. The supply time T of TiCl 4 gas before the plasma generation is set to 2 seconds or more, preferably 2 to 30 seconds, for example, 10 seconds.

Conventionally, TiCl 4 gas supply, which is a Ti-containing source gas, and plasma formation are performed at the same time. Therefore, plasma is formed before sufficient TiCl 4 gas is supplied to the surface of the Si wafer 1, and Si is the bottom surface of the contact. TiSi bonds on the surface of the wafer 1 starts TiSi 2 is a rapid crystal growth with less, depending on the number of TiSi bonds on the bottom surface of the contact hole to grow abnormal uneven crystals formed It had been. For example diameter several TiSi 2 crystals when a relatively large 50nm about the Si contact surface of 0.2μm is formed, relatively is small 20nm about the 10-20 TiSi 2 crystals are formed. Conventionally, the contact resistance has been increased due to this. However, as in this embodiment, TiCl 4 gas, which is a Ti-containing source gas, is supplied for a predetermined time without first generating plasma. By gradually forming Ti-Si bonds over the entire surface, sufficient Ti-Si bonds are formed before TiSi 2 starts crystal growth. Therefore, uniform TiSi 2 crystal growth is caused by plasma generation after a predetermined time, and crystal grains and crystallinity (orientation) become uniform. For this reason, the titanium silicide itself has a low resistance, and the contact between the titanium silicide and the Si wafer 1 becomes uniform, so that the contact resistance can be lowered.

In the present embodiment, similarly to the first embodiment, the TiCl 4 gas supply and the reduction gas H 2 gas supply + plasma generation can be alternately performed in the Ti film formation. In this case, the first supply of TiCl 4 corresponds to the preflow.

Next, a third embodiment of the present invention will be described.
In the third embodiment, a contact hole is formed on the Si wafer 1 in the same manner as in FIGS. 4A and 4B, and then an oxide film on the surface of the Si wafer is formed by plasma using high frequency. Remove. Subsequently, a TiSi 2 film is formed as in FIG. The process of forming this TiSi 2 film is basically the same as that in FIG. 4C, but here, TiCl 4 gas, which is a Ti-containing source gas, is supplied for a predetermined time without first generating plasma. After Ti—Si bond is generated, when Ti film is formed by generating plasma, TiCl 4 gas, which is a Ti-containing source gas, is first supplied at a low flow rate and then at a high flow rate. . Thereafter, as necessary, the surface of the TiSi 2 film is subjected to nitriding as in FIG.

In the step of forming the TiSi 2 film of the present embodiment, as shown in the timing chart of FIG. 6, first, after the pre-flow by introducing H 2 gas and Ar gas into the chamber 41 at a predetermined flow rate, these causing Ti-Si bonds on the Si wafer 1 to leave the TiCl 4 gas was maintained flow flowing T1 seconds at a predetermined flow rate (low flow F1). Then, the predetermined high frequency power is supplied from the high frequency power source 73 with the TiCl 4 gas flowing at the low flow rate F1, and plasma is generated in the chamber 41 to start the film forming process. By maintaining the supply of the TiCl 4 gas at the low flow rate F1 for T2 seconds, the reaction with Si proceeds slowly. Next, the flow rate of TiCl 4 gas is increased to a high flow rate F2, and the film formation rate is increased to form a film. The TiCl 4 gas flow rate is appropriately set in the range of 0.0005 to 0.02 L / min according to the volume of the chamber. In a Ti film forming apparatus chamber compatible with a 300 mmφ wafer, for example, the low flow rate F1 is set to 0.001 to 0.012 L / min, and the high flow rate F2 is set to 0.012 to 0.020 L / min. In this chamber, for example, the low flow rate F1 is set to 0.0005 to 0.0046 L / min, and the high flow rate F2 is set to 0.0046 to 0.010 L / min. Further, the supply time T1 of TiCl 4 prior to plasma generation is set to, for example, 1 to 30 seconds, and the supply time T2 of TiCl 4 at the low flow rate F1 is set to, for example, 5 to 60 seconds, preferably 5 to 30 seconds. .

When forming a Ti film by generating plasma, if a Ti-containing source gas is supplied from the beginning at a high flow rate for film formation, the reaction with Si proceeds rapidly, as shown in FIG. Although a TiSi 2 crystal having a large particle size is formed and the morphology of the interface between the TiSi 2 film and the Si wafer 1 may be deteriorated, a low flow rate gas is first supplied as in the configuration of this embodiment. Then, by slowly advancing the reaction with Si, it becomes possible to form a uniform TiSi 2 crystal having a small particle size, as shown in FIG. 7B. Accordingly, even when the film formation rate is increased by the subsequent supply of a high flow rate gas, uniform crystal growth can be caused, and as a result, a titanium silicide film having fine and uniform crystal grains can be formed. Therefore, the interface morphology can be improved.

In addition, as in the first embodiment, when a TiSi 2 film forming process is performed by applying Vdc of an absolute value of 200 V or more to the Si wafer, a TiSi 2 crystal having a large particle size is likely to be formed, and the interface morphology Since TiCl 4 is supplied for a predetermined time prior to plasma generation in this embodiment, plasma is first generated while TiCl 4 is supplied at a low flow rate, and a Ti film is formed to form an interface morphology. The method of improving is particularly effective in such a case.

Next, experimental results confirming the effects of the present invention will be described.
(1) Experiment of 1st Embodiment Here, first, plasma processing using high frequency was performed on the Si wafer surface using the apparatus of FIG. The conditions at this time were such that the power of the high frequency power supply 18 was 500 W, the power of the bias high frequency power supply 31 was 800 W, and Vdc was −530 V. Thereafter, using the apparatus shown in FIG. 3, a treatment was performed at a susceptor temperature of 640 ° C. and a wafer temperature of 620 ° C. for 31 seconds to form a 43 nm thick TiSi 2 film.

The X-ray diffraction profile at that time is shown in FIG. As shown in FIG. 8, the TiSi 2 film formed according to Embodiment 1 has a strong peak intensity of TiSi 2 having a crystal structure C54, and it has been confirmed that C54 is formed about 70%.

Further, an SEM photograph of the cross section of the hole portion of the sample is shown in FIG. In FIG. 9, etching is performed with hydrofluoric acid, and the TiSi 2 film is removed by etching. As shown in FIG. 9, it is estimated that the portion where the TiSi 2 film was present was thin and uniform, and the crystal grain size was uniform.

(2) Experiment of Second Embodiment Here, after removing the natural oxide film using the apparatus of FIG. 2, in the formation of the TiSi 2 film by the apparatus of FIG. 3, TiCl 4 is formed for 10 seconds prior to plasma generation. Supplied. Susceptor temperature 640 ° C., at a wafer temperature 620 ° C. for 20 seconds treatment was deposited TiSi 2 film having a thickness of 27 nm.

The X-ray diffraction profile at that time is shown in FIG. As shown in FIG. 10, the peak of TiSi 2 having a crystal structure C54 was observed, confirming that C54 was generated.

Further, an SEM photograph of a cross section of the hole portion of the sample is shown in FIG. In FIG. 11, etching is performed with hydrofluoric acid, and the TiSi 2 film is removed by etching. As shown in FIG. 11, in this case as well, it is assumed that the portion where the TiSi 2 film was present was thin and uniform, and the crystal grain sizes were uniform.

(3) Conventional Sample FIG. 12 shows an X-ray diffraction profile (A) of another part of the sample manufactured according to the first embodiment and Vdc after plasma treatment under normal natural oxide film removal conditions. The X-ray diffraction profile (B) of the filmed sample is compared with the X-ray diffraction profile (C) of the sample formed without performing such plasma treatment. As shown in FIG. 12, (A) has a high peak of C54, whereas in the case of (B) in which the plasma treatment was performed under normal conditions, the TiSi 2 peak of crystal structure C54 was hardly seen. The crystal structure was substantially C49, and when the plasma treatment of (C) was not performed, the peak of C49 was low and it was confirmed that the crystallinity was poor.

Further, FIG. 13 shows an SEM photograph of a cross section of a hole portion of a conventional sample not subjected to the processing of the present invention. In FIG. 13, etching is performed with hydrofluoric acid, and the TiSi 2 film is removed by etching. As shown in FIG. 13, the portion where the TiSi 2 film was present is thick and non-uniform, and it is estimated that the crystal grain size is non-uniform.

Note that the present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the idea of the present invention. For example, in the above embodiment, the plasma processing using the high frequency performed prior to the formation of the TiSi 2 film is performed using ICP plasma, but the present invention is not limited to this, and parallel plate plasma (capacitive coupling plasma) is used. Alternatively, it may be performed by microwave plasma in which microwaves are directly introduced into the chamber. However, ICP plasma is preferable because it is less likely to cause unnecessary damage to the object to be processed. In the case of removing the natural oxide film as in the second embodiment, remote plasma with little damage to the substrate can be suitably used. Furthermore, although the example using the Si wafer as the base of the TiSi 2 film has been shown, the present invention is not limited to this, and poly-Si may be used, and not only Si but also metal silicide may be used. Furthermore, the case where TiCl 4 gas is used as the source gas has been described as an example. However, the present invention is not limited to this, and any Ti-containing source gas may be used. For example, TDMAT (dimethylamino titanium) as organic titanium, TDEAT (diethylamino titanium) or the like can also be used. Furthermore, the case where a titanium silicide film is formed using a Ti-containing source gas has been described as an example. However, the present invention is not limited to this. For example, a metal-containing source such as Ni, Co, Pt, Mo, Ta, Hf, Zr, etc. The same effect can be obtained when a silicide film of these metals is formed using a gas.

In the third embodiment, after removing the natural oxide film, the Ti-containing source gas is supplied for a predetermined time without generating plasma, and then the Ti-containing source gas is initially supplied at a low flow rate and then at a high flow rate. While the TiSi 2 film is formed by generating plasma while supplying, such a method of forming the TiSi 2 film can also be applied when the natural oxide film is not removed. In this case, the effect that the crystal grain size of the TiSi 2 film can be reduced can be maintained, and as a result, the interface morphology can be improved.

Sectional drawing for demonstrating each process of the film-forming method which concerns on the 1st Embodiment of this invention. Sectional drawing which shows schematic structure of the apparatus which processes the surface of Si wafer with the plasma using a high frequency. Sectional drawing which shows schematic structure of Ti film-forming apparatus. Sectional drawing for demonstrating each process of the film-forming method which concerns on the 2nd Embodiment of this invention. The chart which shows the timing of gas supply and plasma generation in the TiSi2 film formation process in the 2nd Embodiment of this invention. The third chart showing the timing of gas supply and the plasma generated in the TiSi 2 film forming step in the embodiment of the present invention. (A), at the time of forming a Ti film by generating a plasma, a diagram schematically showing a cross section of the TiSi 2 crystals in the case of supplying gas from the first at a high flow rate, (b), the present schematically shows a third cross section of the TiSi 2 crystals formed by the embodiment of the invention. It shows the X-ray diffraction profile of the first embodiment TiSi 2 film was produced by embodiments of the present invention. First scanning electron microscope (SEM) photograph of a cross section of the TiSi 2 film fabricated in accordance with embodiments of the present invention. The figure which shows the X-ray-diffraction profile of the TiSi2 film | membrane manufactured by the 2nd Embodiment of this invention. The scanning electron microscope (SEM) photograph of the cross section of the TiSi2 film | membrane manufactured by the 2nd Embodiment of this invention. And the 1 TiSi 2 film X-ray diffraction profile of the produced by embodiments of the present invention, TiSi 2 film X-ray diffraction profile and was deposited after the plasma treatment by the Vdc to a normal value -200V It illustrates by comparing the X-ray diffraction profile of the TiSi 2 film formed without such a plasma treatment. Scanning electron microscopy of the cross section of the TiSi 2 film produced by the conventional method (SEM) photograph.

Explanation of symbols

1 Si wafer 2 interlayer insulating layer 3 contact hole 4 TiSi 2 film 10 plasma processing apparatus 11 chamber 12 the bell jar 13 susceptor 17 coil 18 plasma formation high-frequency power supply 40 Ti film formation apparatus of the high frequency power source 20 a gas supply mechanism 31 bias applied for 41 Chamber 42 Susceptor 50 Shower head 60 Gas supply mechanism 62 TiCl 4 gas source 73 High frequency power supply

Claims (4)

  1. A film forming method for forming a metal silicide film on a Si-containing portion of an object to be processed,
    Using a high frequency of the Si-containing moiety, as a gas for plasma treatment, Ar, Ne, He, or Ar, Ne, combined with any of He and H 2, or Ar, Ne, and either the NF 3 of He a step of processing by plasma using combined gas,
    Supplying a metal-containing source gas containing a metal in a metal silicide to be formed on the Si-containing portion that has been treated with the plasma, generating a plasma to form a metal film made of the metal, A step of forming a metal silicide film by a reaction between the metal film at that time and Si in the Si-containing portion,
    The treatment by plasma of the Si-containing moieties, have row while applying the absolute value of 200V or more DC bias voltage to the workpiece (Vdc),
    The step of forming the metal silicide film is characterized in that a metal-containing source gas is supplied for a predetermined time without first generating plasma to generate a metal-silicon bond, and then plasma is generated .
  2.   The film forming method according to claim 1, wherein the Si-containing portion is made of a Si substrate, poly-Si, or metal silicide.
  3. The step of forming the metal silicide film, to claim 1 or claim 2, characterized in that repeated a plurality of times and reduction of the metal-containing raw material gas by supplying supply and plasma and reducing gas of the metal-containing source gas The film-forming method of description.
  4. 4. The film forming method according to claim 1 , wherein the metal is selected from Ti, Ni, Co, Pt, Mo, Ta, Hf, and Zr. 5.
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JP2003291667A JP4451097B2 (en) 2002-10-17 2003-08-11 Deposition method
PCT/JP2004/007554 WO2005015622A1 (en) 2003-08-11 2004-05-26 Film forming method
KR1020067002771A KR100822493B1 (en) 2003-08-11 2004-05-26 Film forming method
CN 200480010470 CN1777977B (en) 2003-08-11 2004-05-26 Film forming method
KR1020077023634A KR100884852B1 (en) 2003-08-11 2004-05-26 Film forming method
US11/350,799 US20060127601A1 (en) 2003-08-11 2006-02-10 Film formation method

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US7476618B2 (en) * 2004-10-26 2009-01-13 Asm Japan K.K. Selective formation of metal layers in an integrated circuit
US20070031609A1 (en) * 2005-07-29 2007-02-08 Ajay Kumar Chemical vapor deposition chamber with dual frequency bias and method for manufacturing a photomask using the same
JP5204964B2 (en) * 2006-10-17 2013-06-05 ルネサスエレクトロニクス株式会社 Manufacturing method of semiconductor device
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