Method of forming contact layer

A method of forming a contact layer on a substrate having a contact hole to make a contact between the substrate and a buried metal material, includes disposing the substrate in a chamber, introducing a Ti source gas, a reducing gas and an Si source gas into the chamber, and converting the Ti source gas, the reducing gas and the Si source gas into plasma to form a TiSix film on the substrate. A portion of the TiSix film in a bottom of the contact hole corresponds to the contact layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No. 2013-267707, filed on Dec. 25, 2013, in the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present disclosure relates to a method of forming a contact layer on a substrate to make a contact between the substrate and a buried metal material.

BACKGROUND

In manufacturing semiconductor devices, in response to a recent request for high densification and high integration, circuitry tends to have a multi-layered wiring structure. For this reason, a burying technique for an electrical connection of a contact hole which connects an Si substrate as the lower layer and a wiring layer as the upper layer becomes important.

In order to make an ohmic contact between a metal wire (plug) used to bury such a contact hole and an Si substrate as the lower layer, a Ti film is formed on an inner side of the contact hole by a chemical vapor deposition (CVD) method prior to burying the contact hole. Thereafter, a contact area is formed by allowing the base Si substrate to react with the Ti film and selectively growing a TiSixlayer on the Si diffusion layer at the bottom of the contact hole, thereby obtaining good ohmic resistance. The described above is a well-known technique.

On the other hand, recently, an Si substrate containing carbon (C) is sometimes used in a logic device and the like. If the above-described technique is applied to the C-containing Si substrate, the Si base substrate becomes difficult to react with Ti, and C is introduced into the contact area, thereby increasing resistance. In addition, along with miniaturization of semiconductor devices, a diffusion layer on a substrate gradually narrows, and accordingly, the formation of the contact layer using the reaction with the substrate is limited.

SUMMARY

Some embodiments of the present disclosure provide a method capable of forming a contact layer without influence of a base substrate.

According to one embodiment of the present disclosure, there is provided a method of forming a contact layer on a substrate having a contact hole to make a contact between the substrate and a buried metal material, the method including disposing the substrate in a chamber, introducing a Ti source gas, a reducing gas and an Si source gas into the chamber, and converting the Ti source gas, the reducing gas and the Si source gas into plasma to form a TiSixfilm on the substrate, a portion of the TiSixfilm in a bottom of the contact hole corresponding to the contact layer.

According to another embodiment of the present disclosure, there is provided a method of forming a contact layer on a substrate having a contact hole to make a contact between the substrate and a buried metal material, the method including disposing the substrate in a chamber, introducing an Si source gas into the chamber to form an Si film on a portion of the substrate in a bottom of the contact hole, introducing a Ti source gas and a reducing gas into the chamber into the chamber, converting the Ti source gas and the reducing gas into plasma to form a Ti film on the substrate, and reacting the Ti film with the Si film, thereby forming a contact layer consisting of TiSixin the bottom of the contact hole.

DETAILED DESCRIPTION

In the following description, mL/min is used as a unit of a flow rate of a gas. Since a volume of a gas largely changes depending on temperature and pressure, a converted value into a standard state is used in the present disclosure. In addition, since a flow rate converted to the standard state is commonly represented in sccm (Standard Cubic Centimeter per Minutes), the unit “sccm” will be added. Here, the standard state refers to a state of a temperature of 0 degree C. (273.15K) and a pressure of 1 atm (101,325 Pa).

<Apparatus for Performing Method of Forming Contact Layer>

FIG. 1is a schematic sectional view showing an example of a film forming apparatus for performing a method of forming a contact layer according to the present disclosure.

A film forming apparatus100is configured such that a TiSixfilm, an Si film and a Ti film may be formed by a CVD method while plasma is generated by forming a high frequency electrical field in parallel flat plate electrodes.

The film forming apparatus100includes a mostly circular cylindrical chamber1. In the chamber1, a susceptor2as a mounting table (stage) made of MN to horizontally support an Si wafer (hereinafter, simply referred to as a wafer) W as a substrate to be processed is disposed to be supported by a circular cylinder-shaped support member3installed at the central lower portion of the susceptor2. A guide ring4is installed on the outer edge portion of the susceptor2to guide the wafer W. In addition, a heater5made of a high melting point metal such as molybdenum is embedded in the susceptor2, and the heater5is supplied with power from a heater power supply6to heat the wafer W as the substrate to be processed to a predetermined temperature.

A pre-mix type shower head10, which also functions as an upper electrode of parallel flat plate electrodes, is installed in a ceiling wall1aof the chamber1via an insulating member9. The shower head10has a base member11and a shower plate12, and an outer peripheral portion of the shower plate12is fixed by screws (not shown) to the base member11via an annular intermediate member13to prevent from attaching to each other. The shower plate12is in the shape of a flange and has a recess formed therein, and a gas diffusion space14is defined between the base member11and the shower plate12. The base member11has a flange portion11aformed in an outer periphery of the base member11, and the flange portion11ais supported by the insulating member9. The shower plate12has a plurality of gas discharge holes15formed therein, and the base member11has a gas introduction hole16formed in the vicinity of the center of the base member11.

In addition, the gas introduction hole16is connected to a gas line of a gas supply mechanism20.

The gas supply mechanism20includes a ClF3gas supply source21for supplying a ClF3gas as a cleaning gas, a TiCl4gas supply source22for supplying a TiCl4gas as a Ti compound gas, an Ar gas supply source23for supplying an Ar gas used as a plasma generation gas or a purge gas, an H2gas supply source24for supplying an H2gas as a reducing gas, an NH3gas supply source25for supplying an NH3gas as a nitriding gas, an N2gas supply source26for supplying an N2gas, and an SiH4gas supply source27for supplying an SiH4gas as an Si compound gas. In addition, the ClF3gas supply source21is connected to ClF3gas supply lines28and35, the TiCl4gas supply source22is connected to a TiCl4gas supply line29, the Ar gas supply source23is connected to an Ar gas supply line30, the H2gas supply source24is connected to an H2gas supply line31, the NH3gas supply source25is connected to an NH3gas supply line32, the N2gas supply source26is connected to an N2gas supply line33, and the SiH4gas supply source27is connected to an SiH4gas supply line34. In addition, each of the gas lines is provided with a mass flow controller37and two valves36with the mass flow controller37interposed therebetween.

The ClF3gas supply line28and the Ar gas supply line30are connected to the TiCl4gas supply line29. In addition, the NH3gas supply line32, the N2gas supply line33, the SiH4gas supply line34, and the ClF3gas supply line35are connected to the H2gas supply line31. The TiCl4gas supply line29and the H2gas supply line31are connected to a gas mixing unit38, so that the mixed gas is introduced into the gas introduction hole16through a gas pipe39. Further, the mixed gas reaches the gas diffusion space14through the gas introduction hole16and is discharged to the wafer W in the chamber1through the gas discharge holes15of the shower plate12.

The shower head10is connected to a high frequency power supply41via a matching unit40, and the shower head10is supplied with high frequency power from the high frequency power supply41. The shower head10functions as the upper electrode of the parallel flat plate electrodes. On the other hand, an electrode42which functions as a lower electrode of the parallel flat plate electrodes is embedded in the vicinity of the surface of the susceptor2. Therefore, as the shower head10is supplied with high frequency power, a high frequency electrical field is formed between the shower head10and the electrode42, and the high frequency electrical field causes the processing gas to be converted into plasma. The frequency of the high frequency power supply41is preferably set to 200 kHz to 13.56 MHz, typically 450 kHz in some embodiment.

A transmission line42aconnected to the electrode42is connected to an impedance adjustment circuit43. The impedance adjustment circuit43is to increase a current by decreasing the impedance of the transmission line42aviewed from a place P where plasma is generated and, for example, includes a coil44and a variable capacitor45. The current flowing in the transmission line42ais detected by a sensor46, and reactance of the impedance adjustment circuit43is controlled based on the detected value.

In addition, the base member11of the shower head10is provided with a heater47for heating the shower head10. The heater47is connected to a heater power supply48, and the shower head10is heated to a desired temperature by supplying power to the heater47from the heater power supply48. A recess formed in the upper portion of the base member11is provided with a thermally insulating member49.

The chamber1has a circular hole50formed in the central portion of a bottom wall1bof the chamber1, and the bottom wall1bis provided with an exhaust chamber51protruding downward to cover the hole50. An exhaust pipe52is connected to a lateral surface of the exhaust chamber51, and an exhaust unit53is connected to the exhaust pipe52. In addition, the exhaust unit53operates to enable the interior of the chamber1to be depressurized to a predetermined degree of vacuum.

Three wafer support pins54(only two of which are shown) for supporting and lifting the wafer W are installed in the susceptor2such that the wafer support pins54protrude from and retract into the surface of the susceptor2, and the wafer support pins54are supported by a support plate55. Further, the wafer support pins54are lifted up and down by a driving mechanism56such as an air cylinder via the support plate55.

A lateral side of the chamber1is provided with a gate57for loading and unloading the wafer W between the chamber1and a wafer transfer chamber (not shown) adjacent thereto, and a gate valve58for opening and closing the gate57.

The heater power supplies6and48, the valves36, the mass flow controllers37, the matching unit40, the high frequency power supply41, the variable capacitor45, the driving mechanism56, and the like, which constitute the film forming apparatus100, are configured to be connected to and controlled by a control unit60provided with a microprocessor (computer). In addition, the control unit60is connected to a user interface61having a keyboard through which an operator performs a command input to manage the film forming apparatus100, a display configured to visually display the operational states of the film forming apparatus100and the like. In addition, the control unit60is connected to a storage unit62configured to store programs for realizing a variety of processes performed by the film forming apparatus100under the control of the control unit60or programs, i.e., processing recipes, for executing processes in the respective components of the film forming apparatus100according to various processing conditions. The processing recipes are stored in a storage medium62ain the storage unit62. The storage medium may be a stationary medium such as a hard disk or a portable medium such as a CD-ROM or a DVD. Alternatively, the recipes may be suitably transmitted from other devices via, e.g., a dedicated transmission line. Further, if necessary, a predetermined processing recipe is read out from the storage unit62under instructions from the user interface61and is executed by the control unit60, whereby a desired process is performed in the film forming apparatus100under the control of the control unit60.

<First Embodiment of Method of Forming Contact Layer>

Subsequently, a first embodiment of a method of forming a contact layer which is performed using the film forming apparatus100will be described.

FIGS. 2A to 2Care process sectional views showing the first embodiment of the method of forming a contact layer. In this embodiment, the wafer W has a structure in which an interlayer insulating film111is formed on an Si substrate110and a contact hole112is formed in the interlayer insulating film111to reach an impurity diffusion region110aof the Si substrate110, for example (FIG. 2A). Then, the film forming apparatus100ofFIG. 1is used to form a TiSixfilm113on the entire surface of the wafer W, as will be described in the following (FIG. 2B).

When the TiSixfilm is first formed in the film forming apparatus100, after an internal pressure of the chamber1is adjusted, the gate valve58is opened, and the wafer W having the structure ofFIG. 2Ais loaded into the chamber1from the transfer chamber (not shown) through the gate57. Then, while maintaining the interior of the chamber1at a predetermined degree of vacuum, a pre-flow process is performed by flowing the Ar gas, the H2gas, the TiCl4gas, and the SiH4gas into a pre-flow line (not shown) at a time when the temperature of the wafer W is almost stable by preheating the wafer W. Thereafter, while maintaining a gas flow rate and pressure constant, the line is switched to a line for film formation, thereby introducing these gases into the chamber1through the shower head10.

Then, after the introduction of these gases is initiated, plasma of the Ar gas, the H2gas, the TiCl4gas and the SiH4gas introduced into the chamber1is generated by applying high frequency power to the shower head10from the high frequency power supply41, and the gases which have been converted into plasma are allowed to react on the wafer W heated to a predetermined temperature by the heater5, thereby depositing the TiSixfilm113on the surface of the substrate110. Using the plasma as described above, it is possible to easily form the TiSixfilm on the inside of the contact hole112.

A portion of the TiSixfilm113in contact with the substrate110in the bottom of the contact hole112becomes a contact layer114. In this state, the contact hole112is filled with a metal115, whereby an ohmic contact is formed between the metal115and the impurity diffusion region110aof the substrate110via the contact layer114(FIG. 2C).

In a related art, a contact area has been formed by selectively growing TiSixby the reaction between a Ti film and Si constituting a base substrate. However, the reaction between Si of the base substrate and Ti is difficult to occur in a C-containing Si substrate used in logic devices and the like. In addition, there is a problem in that C is introduced into the contact area to increase resistance, or a narrow diffusion layer involved in the miniaturization of semiconductor devices is hard to handle.

Therefore, in this embodiment, the TiSixfilm113is directly formed on the impurity diffusion region of the substrate110by the CVD method. Accordingly, a good contact layer can be obtained regardless of a condition of the base substrate.

In this case, when the TiSixfilm is formed, the gases for forming the film need to be converted into plasma in order that a good contact layer having fewer impurities is formed.

That is, when the TiSixfilm is formed using the TiCl4gas as a Ti source and the SiH4gas as an Si source, as shown inFIG. 3, Gibbs' free energy in the gas reactions represented in (1) to (4) is near zero (0) and the reaction for producing TiSixis difficult to occur, whereas when the gases are converted into plasma as shown in (5) and (6), Gibbs' free energy has a negative value having a large absolute value and the reaction progresses sufficiently. Therefore, using the plasma promotes the formation of TiSixand the desorption of Cl as impurity, thereby being capable of producing the TiSixfilm of good quality having a low specific resistance.

In addition, it is preferred in some embodiments that a film forming temperature is equal to or less than 500 degrees C. This is because if the film forming temperature exceeds 500 degrees C., there are a possibility for the impurities to be diffused into the contact layer and a possibility of a bad influence on the device. Equal to or less than 450 degrees C. as the film forming temperature is more preferable in some embodiments. However, since the good film quality cannot be obtained if the temperature is too low, equal to or higher than 350 degrees C. is preferable in some embodiments.

In some embodiments, in order to obtain the TiSixfilm of good quality, preferably, the Ar gas as the plasma generation gas is ionized by using maximally large power and the TiCl4gas is dissociated by the Ar ions, thereby enabling Cl to be efficiently removed and the TiSixfilm to be formed in the bottom of the contact hole with good reactivity. However, since a portion of the current flows in the wafer W from the plasma and more than half of the current flows in the wall portion of the chamber, if the high frequency power of a sufficiently large output is supplied, the current flowing in the wall portion of the chamber from the plasma becomes large and thus the plasma is destabilized, whereby it is apprehended that abnormal electric discharge or the like may occur.

Therefore, in the film forming apparatus ofFIG. 1, such a problem may be solved by installing the impedance adjustment circuit43on the transmission line42aconnected to the electrode42in the susceptor2to enable impedance of the transmission line42aviewed from the place P is generated to be adjusted.

That is, the supply of the sufficient large power is for promoting the gas dissociation by enlarging a potential difference (V) of plasma sheath between the plasma and the wafer so as to accelerate the ions. According to Ohm's law (V=ZI), if the current (I) flowing to the wafer from the plasma is increased, the potential difference can be enlarged even if the high frequency power is low (wherein, Z is impedance).

There are capacitive components such as the plasma sheath and the susceptor2between the plasma and the wafer, and they function as resistors. As shown inFIG. 4, the impedance adjustment circuit43can cancel the capacitive components and maximally reduce the impedance in the transmission line42a, thereby effectively increasing the current flowing in the transmission line42afrom the plasma through the wafer W. For this reason, the gas dissociation can be promoted even by relatively small power, thereby increasing the reactivity. Further, although, inFIG. 1, the impedance adjustment circuit43uses a combination of the coil44and the variable capacitor45in order that the impedance is adjusted by the variable capacitor45, the present disclosure is not limited thereto.

In addition, by increasing the current flowing in the wafer W from the plasma, it is possible to make the current flowing in the wall portion of the chamber from the plasma relatively small. Thus, the plasma can be stabilized even when the high frequency power is increased.

In this embodiment, the high frequency power equal to or higher than 100 W is preferable in order that the TiCl4gas is sufficiently dissociated to obtain good reactivity, and the high frequency power equal to or less than 3000 W is preferable in order that plasma stability is not decreased and plasma damage does not occur.

In the TiSixfilm of this embodiment, the frequency of the high frequency power supplied from the high frequency power supply41is preferably in a range of 200 kHz to 13.56 MHz, typically 450 kHz. This is because such a frequency is advantageous for converting the Ar gas introduced as the plasma gas into Ar ions having high energy.

The lower the internal pressure of the chamber1is, the further the plasma damage decreases. If the pressure is too low, in-plane uniformity (resistance value) of the TiSixfilm remarkably deteriorates. In addition, if the pressure is too high, the resistance value of the TiSixfilm is undesirably increased. Therefore, in light of this, preferable ranges are defined.

Specific ranges of conditions for forming the TiSixfilm are as follows:

Output of High Frequency Power: 100 to 3000 W

Flow rate of Ar Gas: 100 to 10000 mL/min (sccm)

Internal Pressure of Chamber: 13.3 to 1333 Pa (0.1 to 10 Torr)

Wafer Temperature in Film Formation: 350 to 500 degrees C.

In addition, a time of forming a film is appropriately set according to a film thickness desirous to be obtained. It is preferable that the contact layer114consisting of the TiSixfilm have a thickness of 1 to 10 nm or so.

After the TiSixfilm is formed in the above manner, the TiSixfilm may be subjected to nitriding as necessary. In the nitriding, after the formation of the TiSixfilm is terminated, the supply of the TiCl4gas and the SiH4gas is stopped, while the H2gas and the Ar gas continue to flow. While the interior of the chamber1is heated at an appropriate temperature, the NH3gas as a nitriding gas is allowed to flow and the processing gases are converted into plasma by applying high frequency power to the shower head10from the high frequency power supply41. Then, the surface of the TiSixfilm is nitrided by the plasma of the processing gases.

After the TiSixfilm is formed or subjected to the nitriding, the gate valve58is opened, and the wafer W is unloaded to the wafer transfer chamber (not shown) through the gate57.

In this way, the formation of the TiSixfilm and, as necessary, the nitriding the surface of the TiSixfilm is performed on a predetermined number of wafers and then the chamber1is cleaned. The cleaning process is performed, in a state where no wafer is present in the chamber1, by introducing the ClF3gas into the chamber1from the ClF3gas supply source21through the ClF3gas supply lines28and35and by heating the shower head10at an appropriate temperature to perform dry cleaning.

In addition, although the TiCl4gas is used as the Ti source gas, the H2gas is used as the reducing gas, the SiH4gas is used as the Si source gas, and the Ar gas is used as the plasma generation gas in this embodiment, the present disclosure is not limited thereto.

Further, although the Ti source gas, the reducing gas, and the Si source gas are simultaneously supplied to form the TiSixfilm by plasma CVD in this embodiment, the TiSixfilm may be formed by an atomic layer deposition (ALD) method with plasma, in which a purge by the purge gas such as Ar gas or N2gas is repeated between the supply of the Ti source gas and reducing gas and the supply of the Si source gas or among the supply of the Ti source, the supply of the reducing gas and the supply of the Si source gas.

<Second Embodiment of Method of Forming Contact Layer>

Subsequently, a second embodiment of the method of forming a contact layer which is performed using the film forming apparatus100will be described.

FIGS. 5A to 5Dare sectional views showing the second embodiment of the method of forming a contact layer. In this embodiment, as shown inFIGS. 5A to 5D, in the same manner as the first embodiment, the wafer W has a structure in which, for example, an interlayer insulating film111is formed on an Si substrate110and a contact hole112is formed in the interlayer insulating film111to reach an impurity diffusion region110aof the Si substrate110(FIG. 5A). Then, the film forming apparatus100is used to selectively form an Si film116in the region of the Si substrate110in the bottom of the contact hole112(FIG. 5B).

When the Si film116is formed, the wafer W having the structure ofFIG. 5Ais loaded into the chamber1from the transfer chamber (not shown) through the gate57. After the wafer W is preheated and a pre-flow process of the SiH4gas and the Ar gas is performed, while maintaining a gas flow rate and pressure constant, the line is switched to a line for film formation, thereby introducing the SiH4gas into the chamber1through the shower head10to selectively form the Si film116on the region of the Si substrate110in the bottom of the contact hole112. Here, when the Ar gas is introduced, high frequency power may be applied to the shower head10from the high frequency power supply41to generate plasma.

At this time, specific conditions for forming the film are as follows:

Internal Pressure of Chamber: 13.3 to 1333 Pa (0.1 to 10 Torr)

Wafer Temperature in Forming Film: 350 to 500 degrees C.

Thickness of Si Film: 1 to 10 nm

After the Si film116is formed, a Ti film117is formed on the entire surface, and a contact layer118consisting of TiSixis formed by the reaction of the Si film116with the Ti film117in the bottom of the contact hole112(FIG. 5C). In this state, the contact hole112is filled with a metal119, whereby an ohmic contact is formed between the metal119and the impurity diffusion region of the substrate110via the contact layer118(FIG. 5D).

The Ti film is formed in the apparatus ofFIG. 1after the Si film is formed and then the interior of the chamber1is purged. After the purge, a pre-flow process is performed by flowing the Ar gas, the H2gas, and the TiCl4gas into a pre-flow line (not shown). Thereafter, while maintaining a gas flow rate and pressure constant, the line is switched to a line for film formation, thereby introducing these gases into the chamber1through the shower head10. After the introduction of these gases is initiated, plasma of the Ar gas, the H2gas, and the TiCl4gas introduced into the chamber1is generated by applying high frequency power to the shower head10from the high frequency power supply41, and the TiCl4gas and the H2gas having been converted into plasma react on the wafer W heated to a predetermined temperature by the heater5, thereby forming the Ti film117on the surface of the substrate110. Then, the heat and plasma when the Ti film117is formed causes the Si film116formed in the bottom of the contact hole112to react with the Ti film117, thereby forming the contact layer118consisting of TiSix. At this time, as shown inFIG. 5C, only a portion of the Ti film117may be allowed to react with the Si film116, or the entirety of the Ti film117may be allowed to react with the Si film116. In order to promote the reaction at this time, an annealing process may be performed after the Ti film is formed.

In this embodiment, since the Si film116is formed on the impurity diffusion region of the substrate110by the CVD method, the Ti film117is formed thereon, and the contact layer118consisting of TiSixis formed by the reaction, a good contact layer can be obtained regardless of a condition of the base substrate, in the same manner as the first embodiment.

Since the TiSixlayer is obtained by forming the Si film and then forming the Ti film by the plasma CVD method as described above, the decomposition of TiCl4which is the Ti source and the desorption of Cl are promoted. Thus, the Ti film of good quality is formed, and the contact layer consisting of TiSixformed by the reaction of the Ti film with the Si film has few impurities and thus has low resistance.

In the same manner as the formation of the TiSixfilm according to the first embodiment, it is preferred in some embodiments that a film forming temperature of the Ti film is equal to or less than 500 degrees C. This is because if the film forming temperature exceeds 500 degrees C., it is possible that the impurities may be diffused onto the contact layer or a bad influence on the device may be caused. The temperature equal to or less than 450 degrees C. is more preferable in some embodiments. However, since the good film quality cannot be obtained if the temperature is too low, the temperature equal to or higher than 350 degrees C. is preferable in some embodiments.

Further, in the same manner as the first embodiment, as the impedance of the transmission line42aviewed from the place P where the plasma is generated may also be adjusted by the impedance adjustment circuit43installed on the transmission line42aconnected to the electrode42in the susceptor2in the Ti film formation according to this embodiment. This allows the gas dissociation to be promoted by effectively increasing the current flowing in the transmission line42afrom the plasma through the wafer W without applying large power, thereby obtaining a good reactivity.

In addition, by increasing the current flowing in the wafer W from the plasma, it is possible to make the current flowing in the wall portion of the chamber from the plasma relatively small. Thus, the plasma can be stabilized even when the high frequency power is increased.

In the same manner as the first embodiment, when the Ti film is formed according to this embodiment, the frequency of the high frequency power supplied from the high frequency power supply41is also preferably in a range of 200 kHz to 13.56 MHz, typically 450 kHz in some embodiments. In addition, a high frequency power of 100 to 3000 W is preferably used in the same manner as the first embodiment.

In the Ti film formation according to this embodiment, the lower the internal pressure of the chamber1is, the further the plasma damage decreases. If the pressure is too low, in-plane uniformity (resistance value) of the Ti film remarkably deteriorates. In addition, if the pressure is too high, the resistance value of the Ti film is undesirably increased. Therefore, in light of this, preferable ranges are defined.

Specific ranges of conditions for forming the Ti film are as follows:

Output of High Frequency Power: 100 to 3000 W

Flow rate of Ar Gas: 100 to 10000 mL/min (sccm)

Internal Pressure of Chamber: 13.3 to 1333 Pa (0.1 to 10 Torr)

Wafer Temperature in Film Formation: 350 to 500 degrees C.

In addition, a time of forming a film is appropriately set according to a film thickness desirous to be obtained. It is preferable that the TiSixfilm118have a thickness of 1 to 10 nm or so in some embodiments.

After the Ti film is formed in the above manner, the Ti film may be subjected to nitriding as necessary. In the nitriding, after the formation of the Ti film is terminated, the supply of the TiCl4gas is stopped, while the H2gas and the Ar gas continue to flow. While the interior of the chamber1is heated at an appropriate temperature, the NH3gas as a nitriding gas is allowed to flow and the processing gases are converted into plasma by applying high frequency power to the shower head10from the high frequency power supply41. Then, the surface of Ti film is nitrided by the plasma of the processing gases.

After the Ti film is formed or subjected to the nitriding, the gate valve58is opened, and the wafer W is unloaded to the wafer transfer chamber (not shown) through the gate57. Further, in the same manner as the first embodiment, the interior of the chamber1is cleaned by the ClF3gas at a predetermined timing.

In addition, although the SiH4gas is used as the Si source gas when the Si film is formed, the TiCl4gas is used as the Ti source gas when the Ti film is formed, the H2gas is used as the reducing gas, and the Ar gas is used as the plasma generation gas in this embodiment, the present disclosure is not limited thereto.

Further, although the Ti source gas and the reducing gas were simultaneously supplied to form the Ti film by plasma CVD in this embodiment, the Ti film may be formed by an atomic layer deposition (ALD) method with plasma, wherein a purge by the purge gas such as Ar gas or N2gas is repeated between the supply of the Ti source gas and the supply of the reducing gas.

In addition, the present disclosure is not limited to the above-described embodiments but may be variously modified. For example, while it has been described in the above embodiments that a high frequency electrical field is formed to generate plasma by applying high frequency power to the shower head, the high frequency power may be applied to the susceptor. In addition, the plasma generating mechanism is not limited to the parallel flat plate type plasma generating mechanism.

Further, while it has been described in the above embodiment that the Ti film is formed on the silicon substrate, the substrate useful for the present disclosure is not limited to the silicon substrate.

According to the present disclosure, since no reaction with a substrate occurs, a contact layer can be formed without being influenced by a base substrate.