JP2018188724A - Film deposition method and film deposition apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of obtaining a film with high coatability and also supplying an additive gas having a predetermined function while securing high productivity.SOLUTION: A method performs, as many times as predetermined cycles, the steps of: arranging a substrate to be processed in a processing container, and always supplying a carrier gas into the processing container through a first carrier gas flow passage and a second carrier gas flow passage and also supplying a raw material gas into the processing container through a raw material gas flow passage; supplying a purging gas into the processing container through a purging gas flow passage provided separately from the carrier gas so as to purge the raw material gas; supplying a reactant gas into the processing container through a reactant gas flow passage; and supplying the purging gas into the processing container through the purging gas flow passage so as to purge the reactant gas, the method comprising supplying an additive gas having a predetermined function as at least part of the purging gas in at least one of the step of purging the raw material gas and the step of purging the reactant gas.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a film forming method and a film forming apparatus for forming a predetermined film by introducing a predetermined gas into a processing container.

  An atomic layer deposition (ALD) method is sometimes used when a predetermined film is formed on a semiconductor wafer (hereinafter referred to as “wafer”) as a substrate. In ALD, a raw material gas adsorbed on the surface of a wafer and a reactive gas that reacts with the raw material gas are alternately supplied a plurality of times in a processing chamber in a vacuum atmosphere, and atoms of reaction products are supplied to the surface of the wafer. The layers are deposited to form a film. In addition, the source gas and the reactive gas are supplied at an interval from each other to prevent particles from being generated due to a gas phase reaction between the source gas and the reactive gas in a region other than the wafer surface in the processing vessel. Between the time zone in which the source gas is supplied and the time zone in which the reaction gas is supplied, the inside of the processing container is purged by supplying an inert gas, and the inside of the processing container is an inert gas atmosphere. Is replaced by For example, Patent Documents 1 and 2 describe film forming apparatuses that perform such ALD.

That is, Patent Document 1 discloses an upstream end and a downstream end in a gas flow path that connects a supply source of N ₂ (nitrogen) gas, which is a carrier gas and a purge gas, to a processing gas (a raw material gas and a reactive gas) and a processing container. Describes a film forming apparatus that performs ALD with a bypass flow path connected to the. Patent Document 2 discloses a source gas channel connecting a source gas supply source and a processing vessel, a first N ₂ gas channel branched from the source gas channel, a source gas channel, and a first gas channel. A film forming apparatus for performing ALD, which includes a second N ₂ gas flow path for supplying N ₂ gas as a purge gas to a processing container independently of one N ₂ gas flow path, is described.

  In ALD, as described above, it is necessary to purge the inside of the processing container with an inert gas, and since the inert gas is supplied as a carrier gas while the source gas or the reactive gas is supplied, the ALD processing is performed. In the meantime, the inert gas is continuously supplied into the processing container at a predetermined flow rate.

On the other hand, when a predetermined film is formed by such ALD, a treatment with a gas having a predetermined function may be required. As such a technique, in Patent Document 3, when a TiN film is formed, TiCl ₄ gas and NH ₃ gas are alternately supplied with a purge interposed therebetween, and then chlorine gas in the film is desorbed. A technique for supplying H ₂ gas having a hydrogen content is described.

JP 2016-23324 A JP 2014-198872 A JP 2011-6782 A

  By the way, with the progress of miniaturization of wiring, there is a tendency that a concave portion having a large aspect ratio is formed on the surface of a wafer to be ALD. Even when such a concave portion is formed, good step coverage (coverability) is achieved. Therefore, it is required to perform ALD so as to ensure the above. For this purpose, it is conceivable to increase the partial pressure of the source gas in the processing container by increasing the flow rate of the source gas.

  However, when the flow rate of the source gas is increased, if the time for purging is extended in order to prevent the generation of the above particles, the time required for the film forming process becomes longer and the productivity (throughput) decreases. End up.

  In addition, when a predetermined film is formed by ALD, if a treatment with a gas having a predetermined function is performed after the ALD process as in Patent Document 3, if a sufficient effect is to be obtained, the process is performed. As a result, the period of time becomes longer, and the productivity (throughput) also decreases.

  Therefore, according to the present invention, when the source gas and the reaction gas are alternately supplied to the substrate in the processing container and the film is formed by ALD, a film with high coverage can be obtained while ensuring high productivity. It is another object of the present invention to provide a technique capable of supplying an additive gas having a predetermined function.

  In order to solve the above problems, a first aspect of the present invention is to provide a processing container in which a substrate to be processed is accommodated, a raw material gas and a reactive gas for forming a predetermined film on the substrate to be processed, A gas supply mechanism for supplying a carrier gas to be transported to the container and a purge gas for purging the inside of the processing container; an exhaust mechanism for exhausting the inside of the processing container and maintaining the inside of the processing container in a vacuum atmosphere; The gas supply mechanism includes a source gas channel for supplying the source gas into the processing vessel, a reaction gas channel for supplying the reaction gas into the processing vessel, the source gas channel, and the A first carrier gas channel and a second carrier gas channel connected to the reaction gas channel, respectively, for supplying the source gas and the carrier gas of the reaction gas, and the first carrier gas channel. In addition, the processing vessel is provided separately from the second carrier gas flow path, and a purge gas for purging the inside of the processing vessel is controlled in flow rate separately from the first carrier gas and the second carrier gas. A purge gas flow path for supplying an internal gas, an additive gas flow path for supplying an additive gas having a predetermined function to the predetermined film, the source gas flow path, the reactive gas flow path, the first and second A film forming method for forming the predetermined film using a film forming apparatus having an opening / closing valve that independently opens and closes the carrier gas flow path, the purge gas flow path, and the additive gas flow path, A first step of constantly supplying a carrier gas into the processing container via the first carrier gas flow path and the second carrier gas flow path in a state where a substrate to be processed is disposed in the processing container; The raw material A second step of supplying the source gas into the processing vessel via a gas flow channel and adsorbing the source gas on the surface of the substrate to be processed; A third step of purging the raw material gas by supplying a purge gas into the processing vessel via the gas, and supplying the reactive gas into the processing vessel via the reaction gas channel to supply the raw material gas and the reactive gas And a fourth step of stopping the supply of the reaction gas and supplying a purge gas into the processing vessel via the purge gas flow path to purge the reaction gas, The addition of the purge gas as at least part of the purge gas in either or both of the third step of purging the source gas and the fifth step of purging the reaction gas is performed in a predetermined cycle from step 2 to step 5. A film forming method is provided, wherein an additive gas having the predetermined function is supplied through a gas flow path.

  A second aspect of the present invention is a processing container in which a substrate to be processed is accommodated, a raw material gas and a reactive gas for forming a predetermined film on the substrate to be processed, a carrier gas for transporting these to the processing container, And a gas supply mechanism for supplying a purge gas for purging the inside of the processing container, an exhaust mechanism for exhausting the inside of the processing container and maintaining the inside of the processing container in a vacuum atmosphere, and controlling the gas supply mechanism and the exhaust mechanism. And a gas supply mechanism for supplying the source gas into the processing vessel and a reaction gas channel for supplying the reaction gas into the processing vessel. A first carrier gas channel and a second carrier gas channel connected to the source gas channel and the reaction gas channel, respectively, for supplying the source gas and a carrier gas of the reaction gas, The purge gas that is provided separately from the first carrier gas channel and the second carrier gas channel and purges the inside of the processing vessel is separated from the first carrier gas and the second carrier gas. A purge gas passage for controlling the flow rate to be supplied into the processing vessel, an additive gas passage for supplying an additive gas having a predetermined function to the predetermined film, the raw material gas passage, and the reaction gas flow An open / close valve that independently opens and closes the first, second carrier gas flow path, the purge gas flow path, and the additive gas flow path, and the control unit is disposed in the processing container. A first step of constantly supplying a carrier gas into the processing container via the first carrier gas flow path and the second carrier gas flow path in a state where the processing substrate is disposed; and the source gas flow path Through A second step of supplying the source gas into the processing vessel and adsorbing the source gas on the surface of the substrate to be processed; and stopping the supply of the source gas and passing the purge gas channel through the processing vessel A third step of purging the source gas by supplying a purge gas therein, and a fourth step of supplying the reaction gas into the processing vessel via the reaction gas flow path to react the source gas and the reaction gas. And a fifth step of stopping the supply of the reaction gas and supplying the purge gas into the processing container through the purge gas flow path to purge the reaction gas, and from the second step to the fifth step. The process is carried out for a predetermined cycle, and either or both of the third step of purging the raw material gas and the fifth step of purging the reaction gas, or both, is passed through the additive gas flow path as at least a part of the purge gas. Thus, a film forming apparatus is provided that controls to supply an additive gas having the predetermined function.

  According to the present invention, when the source gas and the reaction gas are alternately supplied to the substrate in the processing container to perform film formation, the flow rate is controlled separately in the flow path different from the carrier gas that is constantly supplied. Since the purge gas is supplied and the additive gas having a predetermined function is supplied at the time of purging, the supply of the additive gas having a predetermined function can be obtained while ensuring high productivity. It can be performed.

It is sectional drawing which shows an example of the apparatus for enforcing the film-forming method which concerns on embodiment of this invention. It is a figure which shows an example of the gas supply sequence at the time of enforcing the film-forming method which concerns on the 1st Embodiment of this invention. It is a timing chart which shows typically change of the amount of gas supplied when enforcing the film-forming method concerning a 1st embodiment of the present invention. It is a figure which shows an example of the gas supply sequence at the time of implementing the conventional film-forming method. In the experiment of the first embodiment, the specific resistivity when the TiN film was formed by repeating the steps S1 to S4 for 230 cycles by changing the H ₂ gas flow rate during the purge after the NH ₃ gas flow in step S4. It is a figure which shows a film thickness. It is a figure which shows the recipe time in the experiment of the various sequence of 1st Embodiment, a throughput (wafer / h), a specific resistivity (microohm * cm), and a throughput fall sheet number. It is a figure which shows an example of the gas supply sequence at the time of enforcing the film-forming method which concerns on the 2nd Embodiment of this invention. It is a timing chart which shows typically change of the amount of gas supplied when enforcing the film-forming method concerning a 2nd embodiment of the present invention. It is a figure for demonstrating Rough ratio. It is a diagram showing a relationship between XRF thickness and Rough ratio, varying _{H 2} gas flow rate in the basic experiment to confirm the effect of the _{H 2} gas supply in the second embodiment. It is a diagram showing the relationship between the _{H 2} gas flow rate and Rough ratio minimum thickness in basic experiment to confirm the effect of the _{H 2} gas supply in the second embodiment. It is a diagram showing the relationship between the thickness and resistivity of each flow rate of H ₂ in the basic experiment to confirm the effect of the H ₂ gas supply in the second embodiment. It is a figure for demonstrating the effect of 2nd Embodiment. FIG. 6 is a diagram showing the relationship between the position in the wafer radial direction and the etching amount of the TiN film at each flow rate when the TiCl ₄ flow rate is changed at a temperature of 700 ° C. in a TiN film etching test using TiCl ₄ gas. In the etching tests TiN film by the TiCl ₄ gas, 400 ° C. The temperature at the TiCl ₄ gas flow rate 270 sccm, 500 ° C., at the time of changing the 600 ° C., and the etching amount of the position and the TiN film on the wafer radial direction at each temperature It is a figure which shows a relationship. In the etching tests TiN film by the TiCl ₄ gas, 625 ° C. The temperature at the TiCl ₄ gas flow rate 270sccm, 650 ℃, 675 ℃, when changing a 700 ° C., the etching position and TiN film on the wafer radial direction at each temperature It is a figure which shows the relationship with quantity. TiCl ₄ in the etching test of the TiN film by the gas, the temperature 700 ° C., 100 cycles of the etching in the TiCl ₄ gas flow rate 270 sccm, 200 cycles, the time of changing the 300 cycle, the position and TiN wafer radial direction at each cycle It is a figure which shows the relationship with the etching amount of a film | membrane. In the etching test of the TiN film with TiCl ₄ gas, at a temperature of 700 ° C. and a TiCl ₄ gas flow rate of 270 sccm, when H ₂ gas was not added during the etching test, the radial position when added and the position of the TiN film It is a figure which shows the relationship with the etching amount.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

Here, an example in which a TiN film is formed by ALD using TiCl ₄ as a deposition source gas (precursor gas), NH ₃ gas as a reaction gas, and H ₂ gas as a reforming gas will be described.

<Deposition system>
FIG. 1 is a cross-sectional view showing an example of an apparatus for carrying out a film forming method according to an embodiment of the present invention. The film forming apparatus 1 includes a processing container 11 having a flat circular shape in which a wafer W as a substrate to be processed is accommodated. The wafer W has a recess for forming wiring on the surface.

Film-forming apparatus 1, with respect to the wafer W, and TiCl ₄ (titanium tetrachloride) gas as a source gas (precursor gas) is used as the NH ₃ (ammonia) gas and the carrier gas and purge gas is a reactive gas _{N 2} A gas supply mechanism 2 is provided for supplying the gas and H ₂ gas, which is a reformed gas, into the processing vessel 11.

  A loading / unloading port 12 for the wafer W is formed on the side wall of the processing container 11, and the loading / unloading port 12 is opened and closed by a gate valve 13. In addition, a mounting table 21 for mounting the wafer W in a horizontal state is provided in the processing container 11. A heater 22 for heating the wafer W to a predetermined temperature is embedded in the mounting table 21. A cylindrical cover member 23 is provided around the mounting table 21 so as to surround the mounting table 21.

  The mounting table 21 is supported by the support column 24. The support column 24 extends from the center of the bottom surface of the mounting table 21 through a hole formed in the bottom wall of the processing container 11 and extends below the processing container 11, and a lower end thereof is connected to the lifting mechanism 25. The elevating mechanism 25 moves the mounting table 21 between a processing position on the upper side in the processing container 11 indicated by a solid line in the drawing and a delivery position on the lower side in the processing container 11 indicated by a two-dot chain line in the drawing. Move up and down.

  A flange 26 is attached to the support 24 at a position below the processing container 11. The atmosphere in the processing container 11 is partitioned from outside air between the bottom surface of the processing container 11 and the flange 26, and the mounting table is moved up and down. A bellows 27 that expands and contracts is provided.

  In the vicinity of the bottom surface of the processing vessel 11, three wafer lifting pins 20 (only two are shown) are provided so as to protrude upward from the lifting plate 20a. The wafer lifting pins 20 can be lifted and lowered via a lifting plate 20 a by a lifting mechanism 28 provided below the processing container 11. The wafer elevating pins 20 are inserted into a through hole 29 provided in the mounting table 21 at the delivery position and can protrude and retract with respect to the upper surface of the mounting table 21. By moving the wafer lifting pins 20 up and down in this way, the wafer W is transferred between the wafer transfer mechanism (not shown) and the mounting table 21.

  The ceiling surface of the processing container 11 is formed by a top plate 15. The ceiling surface is formed so as to descend from the central portion toward the peripheral portion, and when the mounting table 21 is located at the processing position, the surface of the mounting table 21, the surface of the cover member 23, and the processing container 11 A flat conical processing space 10 surrounded by the ceiling surface is formed. Two gas supply passages 31 and 32 penetrating the top plate 15 in the thickness direction are formed in the central portion of the top plate 15, and below these gas supply passages 31 and 32, A dispersion plate 33 for dispersing the gas discharged from 31 and 32 in the processing space 10 is provided horizontally, for example.

  An exhaust duct 17 having an annular shape is provided at the upper portion of the processing container 11 so as to surround the side surface of the processing space 10. A slit 17 a is formed in the exhaust duct 17 along the inner peripheral surface. An annular member 16 is formed between the lower portion of the exhaust duct 17 and the cover member 23. The inner peripheral portion of the annular member 16 is close to the cover member 23, and the outer peripheral portion of the annular member 16 is in close contact with the lower portion of the exhaust duct 17. A gap 18 is formed between the cover member 23 and the top plate 15 of the processing container 11. One end of an exhaust pipe 34 is connected to the outer wall of the exhaust duct 17, and the other end of the exhaust pipe 34 is connected via a pressure control valve 35 for adjusting the amount of exhaust and adjusting the vacuum pressure of the processing space 10. A vacuum pump 37 is connected. By operating the vacuum pump 37, the gas in the processing space 10 reaches the exhaust space in the exhaust duct 17 through the gap 18 and the slit 17 a and is exhausted through the exhaust pipe 34.

The gas supply mechanism 2 has a TiCl ₄ gas line 41 and an NH ₃ gas line 61 each connected at one end to the gas supply paths 31 and 32 described above. The TiCl ₄ gas line 41 is supplied with TiCl ₄ gas as a raw material gas, and the NH ₃ gas line 61 is supplied with NH ₃ gas as a reaction gas.

The TiCl ₄ gas line 41, valve V1 from the lower side in this order, a gas storage tank 42, its flow rate adjuster 43 is interposed, the TiCl ₄ gas supply source 44 for supplying TiCl ₄ gas as a process gas at the other end It is connected. The TiCl ₄ gas supply source 44 is a tank that stores TiCl ₄ in a liquid state, and the tank is heated (heated) to vaporize TiCl ₄ in the tank. The TiCl ₄ gas supply source 44 supplies a TiCl ₄ gas line. 41 is supplied with TiCl ₄ thus vaporized.

One end of the first purge gas line 45 is connected to the TiCl ₄ gas line 41 on the downstream side of the valve V1. The first purge gas line 45 is provided with a valve V2, a gas storage tank 46, and a flow rate adjusting unit 47 in order from the lower side. The other end of the first purge gas line 45 is supplied with a purge N ₂ gas. A purge gas supply source 48 is connected.

Furthermore, one end of a first carrier gas line 51 that supplies N ₂ gas as a carrier gas for TiCl ₄ gas is connected to the downstream side of the valve V 2 in the first purge gas line 45. The first carrier gas line 51 is provided with a valve V3 and a flow rate adjusting unit 52 in order from the lower side, and the other end of the first carrier gas line 51 is supplied with N ₂ gas as a carrier gas of TiCl ₄ gas. The first carrier gas supply source 53 is connected. In the first carrier gas line 51, an orifice 54 is formed on the downstream side of the valve V3. Since the downstream diameter of the valve V3 in the first carrier gas line 51 is smaller than the upstream diameter of the valve V3 in the first carrier gas line 51 and the diameter of the gas lines 41, 45, the gas storage tanks 42, 46 cause gas Although the gas is supplied to the lines 41 and 45 at a relatively large flow rate, the gas supplied to the gas lines 41 and 45 by the orifice 54 is prevented from flowing back through the gas line 51.

The carrier gas from the first carrier gas supply source 53 is continuously supplied into the processing container 11 during the processing of the wafer W, and functions as a purge gas when purging. The carrier gas also functions as a backflow prevention gas for preventing the TiCl ₄ gas from flowing back through the first carrier gas line 51.

The NH ₃ gas line 61 has a structure in which the branch line joins after branching into two lines on the upstream side. The NH ₃ gas line 61 after joining is sequentially provided with a gas storage tank 62 and a flow rate adjusting unit 63 from the lower side, and an NH ₃ gas supply source 64 is provided at the end of the NH ₃ gas line 61 after joining. Are connected, and NH ₃ gas is supplied into the processing container 11 from the NH ₃ gas supply source 64. Valves V4 and V5 are provided in the two branch lines, respectively. By forming the flow path branched on the downstream side of the gas storage tank 62 in this way, conductance is increased, and a large flow rate of NH 3 gas can be supplied to the processing container 11.

One end of the second purge gas line 65 is connected to the downstream side of the valve V5 at the branched portion of the NH ₃ gas line 61. The second purge gas line 65, valve V6 from the lower side in this order, a gas storage tank 66, its flow rate adjustment part 67 is interposed, second supplying to the other end of the second purge gas line 65 N ₂ gas for purging A purge gas supply source 68 is connected.

Further, one end of a second carrier gas line 71 for supplying N ₂ gas as a carrier gas of NH ₃ gas is connected to the downstream side of the valve V 6 in the second purge gas line 65. The second carrier gas line 71 is provided with a valve V7 and a flow rate adjusting unit 72 in order from the bottom, and the other end of the second carrier gas line 71 has a supply source of N ₂ gas as a carrier gas of NH ₃ gas. A second carrier gas supply source 73 is connected. In the second carrier gas line 71, an orifice 74 is formed on the downstream side of the valve V7. Since the downstream diameter of the valve V7 in the second carrier gas line 71 is smaller than the upstream side of the valve V7 in the second carrier gas line 71 and the diameter of the gas lines 61, 65, the gas storage tanks 62, 66 cause gas Although the gas is supplied to the lines 61 and 65 at a relatively large flow rate, the gas supplied to the gas lines 61 and 65 by the orifice 74 is prevented from flowing back through the gas line 71.

The carrier gas from the second carrier gas supply source 73 is continuously supplied into the processing container 11 during the processing of the wafer W, and functions as a purge gas when purging. This carrier gas also functions as a backflow prevention gas for preventing the NH ₃ gas from flowing back through the second carrier gas line 71.

One end of an H ₂ gas line 81 for supplying H ₂ gas as an additive gas having a predetermined function is connected downstream of the connection portion of the first purge gas line 45 in the TiCl ₄ gas line 41. The H ₂ gas line 81, valve V8 from the lower side in this order, a gas storage tank 82, the flow rate adjuster 83 is interposed, to the other end of the _{H 2} gas line 81, the _{H 2} gas supply for supplying the _{H 2} gas A source 84 is connected.

One end of a third carrier gas line 91 that supplies N ₂ gas as a carrier gas of H ₂ gas is connected to the downstream side of the valve V8 in the H ₂ gas line 81. The third carrier gas line 91 is provided with a valve V9 and a flow rate adjusting unit 92 in order from the lower side, and a supply source of N ₂ gas as a carrier gas of H ₂ gas is provided at the other end of the third carrier gas line 91. A third carrier gas supply source 93 is connected. In the third carrier gas line 91, an orifice 94 for preventing backflow is formed on the downstream side of the valve V9. The carrier gas also functions as a backflow preventing gas for preventing the H ₂ gas from flowing back through the third carrier gas line 91.

The H ₂ gas line and the H ₂ gas supply source may be connected to the NH ₃ gas line 61 side together with the carrier gas line and the carrier gas supply source, and the TiCl ₄ gas line 41 side and the NH ₃ gas line 61 may be connected. It may be connected to both sides.

The flow rate adjusting units 43, 47, 52, 63, 67, 72, 83, and 92 are configured by a mass flow controller, and adjust and control the flow rate of the gas flowing through the corresponding gas line. In addition, an appropriate thing is used for each flow volume adjustment part according to the temperature of the gas which adjusts a flow volume. The flow rate adjusting unit 43 for the TiCl ₄ gas, which is designed so that it can be heated to adjust the flow rate of TiCl ₄ gas heated to a high temperature is used.

  The gas storage tanks 42, 46, 62, 66, and 82 temporarily store the gas supplied from the gas supply source connected to the corresponding gas line before supplying the gas into the processing container 11. As a result, the gas is raised to a predetermined pressure, and then each gas is supplied from each gas storage tank to the processing container 11. Thereby, a large flow rate gas can be stably supplied to a processing container. The supply / disconnection of each gas from the gas storage tanks 42, 46, 62, 66, 82 to the processing container 11 is performed by opening / closing corresponding valves.

  As described above, in the gas supply mechanism 2, the first carrier gas line 51 includes the valve V3 and the flow rate adjustment unit 52 as the supply control device for the carrier gas, and the first purge gas line 45 includes the valve V3 and the flow rate adjustment. Separately from the unit 52, a valve V2 and a flow rate adjusting unit 47 are provided as purge gas supply control devices. The second carrier gas line 71 includes a valve V7 and a flow rate adjustment unit 72 as carrier gas supply control devices. The second purge gas line 65 includes a purge gas separately from the valve V7 and the flow rate adjustment unit 72. As a supply control device, the valve V6 and the flow rate adjusting unit 67 are provided.

Further, the purge gas is configured to be supplied from the first purge gas line 45 and the second purge gas line 65 to the processing container 11 through the TiCl ₄ gas line 41 and the NH ₃ gas line 61 gas, respectively. 11, not only TiCl ₄ gas and NH ₃ gas remaining in Ti but also TiCl ₄ gas line 41 and NH ₃ gas line 61 remain on the downstream side of valve V 1.
The gas and NH3 gas remaining downstream of the valves V4 and V5 can also be purged.

  The film forming apparatus 1 includes a control unit 100. The control unit 100 includes a computer, and includes a main control unit including a CPU, an input device (keyboard, mouse, etc.), an output device (printer, etc.), a display device (display, etc.), and a storage device (storage medium). Have. The main control unit, for example, opens and closes the valves V1 to V9, adjusts the gas flow rate by the flow rate adjusting units 43, 47, 52, 63, 67, 72, 83, 92, and the pressure in the processing container 11 by the pressure control valve 35. And the operation of each component such as adjustment of the temperature of the wafer W by the heater 22 is controlled. Control of these operations is executed by a processing recipe which is a control program stored in a storage medium (hard disk, optical desk, semiconductor memory, etc.) built in the storage device.

<First Embodiment of Film Formation Method>
Next, a first embodiment of a film forming method in the film forming apparatus 1 configured as described above will be described. The following processing operations are executed based on the processing recipe stored in the storage medium in the control unit 100.

  The film forming method according to the present embodiment forms a TiN film having a relatively high temperature and a low specific resistance on the surface of the wafer W on which an insulating film having fine recesses is formed. A TiN film having a low specific resistance has been demanded. Conventionally, a TiN film formed at a high temperature of about 700 ° C. by ALD has a value of 130 μΩ · cm at a film thickness of 10 nm, but it is even lower. Specific resistance is being demanded. In this embodiment, a TiN film capable of obtaining a lower specific resistance is formed.

First, in a state where the valves V1 to V9 are closed and the mounting table 21 is lowered to the delivery position, the gate valve 13 is opened, and the loading / unloading port 12 is opened from the vacuum transfer chamber (not shown) by the transfer device (not shown). Then, the wafer W is loaded into the processing container 11 and placed on the lift pins 20, the transfer device is retracted, and the gate valve 13 is closed. Then, the wafer W is placed on the mounting table 21 by raising the mounting table 21 to the processing position. The mounting table 21 is heated to a temperature in the range of 400 to 750 ° C. by the heater 22. Then, the valves V3, V7, V9 are opened, and the carrier N _{2 is} supplied from the first to third carrier gas supply sources 53, 73, 93 into the processing container 11 via the first to third carrier gas lines 51, 71, 91. While the gas is supplied, the pressure is maintained at a predetermined reduced pressure, and the temperature of the wafer W is controlled in a range of 400 to 750 ° C., for example, 700 ° C. (In practice, the temperature of the mounting table 21 is 10 ° C. higher than the temperature of the wafer W. About high). At this time, the valves V1, V2, V4, V5, V6, and V8 remain closed. On the other hand, the TiCl ₄ gas and NH ₃ gas from the TiCl ₄ gas supply source 44 and the NH ₃ gas supply source 64, but each of which is supplied to the TiCl ₄ gas line 41 and the NH ₃ gas line 61, valves V1, V4, V5 is By being closed, the TiCl ₄ gas and the NH ₃ gas are stored in the storage tanks 42 and 62, and the pressure in the gas storage tanks 42 and 62 is increased.

  In this state, deposition of a TiN film by ALD is started. FIG. 2 is a diagram showing an example of a gas supply sequence when a TiN film is formed by ALD, and FIG. 3 schematically shows a change in the amount of gas supplied when the TiN film is formed by ALD. It is a timing chart which shows.

As shown in FIGS. 2 and 3, in forming the TiN film by ALD, first, the first to third carrier gas supply sources 53, 73, 93 are left with the valves V 3, V 7, V 9 opened. In the state where the carrier N ₂ gas is continuously supplied from the first to third carrier gas lines 51, 71, 91 from the valve V 1, the valve V 1 is opened, and the TiCl ₄ gas stored in the gas storage tank 42 is removed from the processing container 11 ( It is supplied to the processing space 10) and adsorbed on the surface of the wafer W (step S1).

At this time, the flow rate of the N ₂ gas, which is the carrier gas supplied through the first to third carrier gas lines 51, 71, 91, is preferably 200 to 10,000 sccm, respectively, for a total of 600 to 30,000 sccm. The total of 333 sccm can be 1000 sccm. The pressure in the processing container 11 (processing space 10) is preferably 1 to 9 Torr (113.3 to 1199.7 Pa), for example, 5 Torr (666.5 Pa).

The flow rate of TiCl ₄ gas is preferably 50 to 300 sccm, for example, 150 sccm. The time of step S1 is preferably in the range of 0.03 to 30 sec, and can be set to 0.1 sec, for example.

  In parallel with this step S1, purge gas is supplied from the first purge gas supply source 48 and the second purge gas supply source 68 to the first purge gas line 45 and the second purge gas supply line 65, but the valves V2 and V6 are closed. Thus, the purge gas is stored in the gas storage tanks 46 and 66, and the pressure in the gas storage tanks 46 and 66 is increased.

Next, the carrier N ₂ from the first to third carrier gas supply sources 53, 73, 93 through the first to third carrier gas lines 51, 71, 91 while the valves V 3, V 7, V 9 are opened. In a state where the gas is continuously supplied at the same flow rate, the valve V1 is closed to stop the TiCl ₄ gas, the valves V2 and V6 are opened, and the purge gas stored in the gas storage tanks 46 and 66 is transferred into the processing container 11 (processing space). 10) and exhausted by the vacuum pump 37 through the exhaust pipe 34 to purge the inside of the processing vessel 11 (processing space 10) (step S2).

As described above, by supplying from the gas storage tanks 46 and 66 in a line separate from the carrier gas and in a state where the pressure is increased, a large flow rate, for example, carrier gas is supplied into the processing container 11 (processing space 10). By supplying N ₂ gas as the purge gas at a flow rate larger than the flow rate, the TiCl ₄ gas in the processing vessel 11 can be purged in a short time.

  At this time, the flow rate of the purge gas supplied through the first and second purge gas lines 45 and 65 is preferably 200 to 10000 sccm, respectively, and 400 to 20000 sccm in total, for example, 9000 sccm and 18000 sccm in total. Can do. The time of step S2 is preferably in the range of 0.03 to 30 seconds, and can be set to 0.2 seconds, for example.

In parallel with this step S2, but the TiCl ₄ gas is supplied from the TiCl ₄ gas supply source 44 to the TiCl ₄ gas line 41, the valves V1 is closed, the TiCl ₄ gas is stored in gas storage tank 42 Then, the pressure in the gas storage tank 42 is increased.

Next, the carrier N ₂ from the first to third carrier gas supply sources 53, 73, 93 through the first to third carrier gas lines 51, 71, 91 while the valves V 3, V 7, V 9 are opened. With the gas supplied at the same flow rate, the valves V2 and V6 are closed to stop the purge gas, the valves V4 and V5 are opened, and the NH ₃ gas stored in the gas storage tank 62 is treated with the processing container 11 (processing space 10 ) And react with the TiCl ₄ gas on the surface of the wafer W (step S3). Thereby, a molecular layer of TiN is formed.

At this time, the flow rate of NH ₃ gas is preferably 200 to 10,000 sccm, and can be set to 3800 sccm, for example. The time of step S3 is preferably in the range of 0.03 to 30 seconds, and can be set to, for example, 0.25 seconds.

In parallel with this step S3, purge gas is supplied from the first purge gas supply source 48 and the second purge gas supply source 68 to the first purge gas line 45 and the second purge gas supply line 65, and from the H ₂ gas supply source 84 to the H ₂ gas. Although H ₂ gas is supplied to the line 81, the purge gas is stored in the gas storage tanks 46 and 66, and the H ₂ gas is stored in the gas storage tank 82 because the valves V2, V6, and V8 are closed. The pressure in the gas storage tanks 46, 66, and 82 is increased.

Next, the carrier N ₂ from the first to third carrier gas supply sources 53, 73, 93 through the first to third carrier gas lines 51, 71, 91 while the valves V 3, V 7, V 9 are opened. in a state of continuing to supply the gas at the same flow rate, the NH ₃ gas is stopped by closing the valve V4 and V5, opens the valve V2, V6 and V8, purge gas stored in the gas storage tank 46 and 66, and gas reservoir The H ₂ gas stored in the tank 82 is supplied into the processing container 11 (processing space 10) and exhausted through the exhaust pipe 34 by the vacuum pump 37 to purge the processing container 11 (processing space 10) ( Step S4).

As in step S2, a large flow rate, for example, carrier gas, is supplied into the processing container 11 (processing space 10) by being supplied from the gas storage tanks 46 and 66 in a separate line from the carrier gas and in a state where the pressure has increased. It is possible to purge the NH ₃ gas in the processing container 11 in a short time by supplying N ₂ gas as the purge gas at a flow rate larger than the above flow rate. Further, by supplying H ₂ gas during the purge, the TiN molecular layer is modified by H ₂ gas. Further, since the treatment with H ₂ gas is performed at the time of purging, the reforming treatment can be performed without reducing the throughput. Further, it is possible to supply the flow rate of H ₂ gas at any flow rate, it is possible to perform modification with H ₂ in a short time of the purge step by supplying H ₂ gas at a high flow rate.

At this time, the flow rate of the purge gas supplied through the first and second purge gas lines 45 and 65 is preferably 200 to 10000 sccm, respectively, and 400 to 20000 sccm in total, for example, 9000 sccm and 18000 sccm in total. Can do. Further, the flow rate of the H ₂ gas supplied through the H ₂ gas line 81 is preferably 200 to 10,000 sccm, for example, 7000 sccm. The time of step S4 is preferably in the range of 0.03 to 30 sec, and can be set to 0.3 sec, for example.

In parallel with this step S4, although NH ₃ gas is supplied from the NH ₃ gas supply source 64 to the NH ₃ gas line 61, the valves V4 and V5 are closed, the NH ₃ gas is a gas storage tank 62 The pressure in the gas storage tank 62 is increased.

By performing steps S1 to S4 as described above for a predetermined cycle of one cycle or more, a modified TiN film having a predetermined film thickness can be obtained. That is, in the present embodiment, annealing is performed in a H ₂ gas atmosphere in the purge process (step S4) after the TiN molecular layer is formed, so that the TiN crystal grains become large, and the above steps S1 to S4 are performed. By performing a predetermined cycle, the crystal grains of the TiN film can be enlarged. For this reason, a TiN film having a low specific resistivity can be obtained.

  After the TiN film having a predetermined thickness is formed in this manner, the inside of the processing container 11 is purged with the purge gas, the mounting table 21 is lowered to the delivery position, the gate valve 13 is then opened, and the transfer device (FIG. The wafer W after processing is carried out to a vacuum transfer chamber (not shown) through the loading / unloading port 12.

Conventionally, as shown in FIG. 4, the carrier gas of TiCl ₄ gas and NH ₃ gas was continuously supplied and the carrier gas was used as the purge gas, but the carrier gas was supplied in an amount necessary for purging the processing vessel. This increases the amount of carrier gas supplied. On the other hand, in order to ensure good step coverage (coverability), it is required to increase the supply amount of the TiCl ₄ gas, which is the raw material gas, to increase the partial pressure of the raw material gas in the processing vessel. the flow rate of the carrier gas supplied is large, an attempt to increase the partial pressure of TiCl ₄ gas, it is necessary to extremely increase the supply amount of the TiCl ₄ gas, throughput becomes longer purge time, i.e. the productivity decreases Resulting in. Further, when increasing the supply amount of the TiCl ₄ gas, since the deposition amount of the TiCl ₄ gas into the processing vessel and piping increases, the frequency of maintenance is also increased. Furthermore, as shown in Patent Document 3, since the process using H ₂ gas is performed separately from the ALD process, the productivity (throughput) is further reduced accordingly.

In contrast, in the present embodiment, the first and second purge gas lines 45 and 65 are provided separately from the first and second carrier gas lines 51 and 71 for supplying the carrier gas of TiCl ₄ gas and NH ₃ gas. The first and second purge gas lines 45 and 65 are provided separately from the valves V3 and V7 of the first and second carrier gas lines 51 and 71 and the flow rate adjustment units 52 and 72, and the valves V2, V6, and Since the flow rate adjusting sections 47 and 67 are provided, the flow rate of the purge gas can be increased only during the purge, and there is no need to increase the flow rate of the carrier gas. For this reason, coverage (step coverage) can be improved without greatly increasing the flow rate of the TiCl ₄ gas as the source gas, and good coverage (step coverage) of 90% or more can be achieved without reducing productivity. Can be obtained. Further, since the treatment with H ₂ gas for reducing the specific resistance is performed at the time of purging after the NH ₃ gas is supplied, there is almost no decrease in productivity (throughput) due to the H ₂ gas treatment without affecting the ALD. It does not occur. Further, since the purge gas and the H ₂ gas can be supplied while reducing the carrier gas at the time of purging, the reforming by the H ₂ is performed in a short purge process by supplying a large flow rate of the H ₂ gas. Is possible.

Further, the purge gas is supplied from the gas storage tanks 46 and 66 in a state where the pressure is increased, so that the purge gas is supplied into the processing container 11 (processing space 10) at a large flow rate, for example, a flow rate larger than the flow rate of the carrier gas. By supplying, the TiCl ₄ gas or the NH ₃ gas in the processing container 11 can be purged in a short time. For this reason, the throughput can be further increased.

In the present embodiment, steps S1 to S4 may be performed for a plurality of cycles, and the time of step S4 in the final cycle may be increased. The time at this time is preferably 60 sec or less. Thereby, although the throughput is somewhat reduced, the effect of the H ₂ gas treatment can be further increased and the specific resistance can be further decreased.

Further, when steps S1 to S4 are performed a plurality of times, the time of step S4 may be lengthened for a predetermined period. In this case, the throughput is further reduced, but the effect of the H ₂ gas treatment can be further enhanced, and the specific resistance can be further reduced.

Further, in step S4, both the purge gas and the H ₂ gas are used. However, since the H ₂ gas also functions as the purge gas, the ratio of the purge gas and the H ₂ gas is arbitrary, and all may be H ₂ gas.

Furthermore, in the present embodiment, H ₂ gas may be supplied also in step S2, which is a purge process after supplying TiCl ₄ gas.

Next, the experimental results of this embodiment will be described.
FIG. 5 shows the resistivity and film thickness when a TiN film was formed by repeating steps S1 to S4 for 230 cycles while changing the H ₂ gas flow rate during the purge after the NH ₃ gas flow in step S4. FIG. As shown in this figure, it can be seen that the specific resistance decreases when the H ₂ gas flow rate is 2000 sccm or more.

Next, the recipe time, throughput, and resistivity in various sequence experiments were determined. Here, the flow rate of N ₂ gas, which is a carrier gas of TiCl ₄ gas and NH ₃ gas, is continuously supplied at a rate of 500 sccm, the flow rate of TiCl ₄ gas in Step S1 is 150 sccm, and the N ₂ gas that is the purge gas in Steps S2 and S4 The flow rate of 9000 sccm, the NH ₃ gas flow rate of step S3 is 3800 sccm, the H ₂ gas flow rate of step S4 is 7000 sccm, and the standard times of steps S1, S2, S3, and S4 are 0.1 sec and 0 sec, respectively. .2 sec, 0.25 sec, and 0.3 sec. When steps S1 to S4 are repeated for 230 cycles without adding H ₂ gas (sequence 1), when H ₂ gas is added to step S4 and steps S1 to S4 are repeated for 230 cycles (sequence 2), It was added _{H 2} gas of step S1~S4 repeated 229 cycles to step S4, if the time of the last cycle only step S4 was 15 sec (sequence 3), with the addition of _{H 2} gas to step S4 step S1~S4 Is repeated for 229 cycles, and the time of step S4 is set to 60 sec only in the final cycle (sequence 4), H ₂ gas is added to step S4, steps S1 to S4 are repeated for 46 cycles, and the time of step S4 of the 47th cycle is set. When this 47 cycle is repeated 5 times (15 seconds) Was performed on the scan 5). The results are shown in FIG.

FIG. 6 shows the recipe time, throughput (wafer / h), specific resistivity (μΩ · cm), and number of throughput drops in each sequence. As shown in this figure, in the sequence 2 in which H ₂ gas is added in step S4, the specific resistance is reduced from 131 μΩ · cm to 117 μΩ · cm without reducing the throughput, compared to the sequence 1 in which H ₂ gas is not added. Confirmed to do. In addition, with respect to sequences 3 and 4 in which the time of step S4 of the final cycle is increased, the specific resistance is further reduced to 109 μΩ · cm and 104 μΩ · cm, although the throughput is slightly reduced according to the time. It was. Further, the specific resistance of Sequence 5 in which the time of step S4 was periodically increased was reduced to 105 μΩ · cm, but the throughput was reduced. However, in the sequences 3 to 5, although the throughput was lowered, it was within an allowable range. In addition, a good value of 90% or more was obtained for the step coverage.

<Second Embodiment of Film Formation Method>
Next, a second embodiment of the film forming method will be described.

  The film forming method according to the present embodiment forms an extremely thin TiN film of 2 nm or less, further 1 nm or less on a fine pattern with a high continuity as well as high coverage by a low temperature film forming process applied to logic or the like. Is.

First, as in the first embodiment, with the valves V1 to V9 closed and the mounting table 21 lowered to the delivery position, the gate valve 13 is opened and a vacuum transfer chamber (not shown) is formed by a transfer device (not shown). The wafer W is loaded into the processing container 11 from the loading / unloading port 12 through the loading / unloading port 12, placed on the lift pins 20, the transfer device is retracted, and the gate valve 13 is closed. Then, the wafer W is placed on the mounting table 21 by raising the mounting table 21 to the processing position. In the present embodiment, the mounting table 21 is heated to a temperature in the range of 400 to 500 ° C. by the heater 22. Then, the valves V3, V7, V9 are opened, and the carrier N _{2 is} supplied from the first to third carrier gas supply sources 53, 73, 93 into the processing container 11 via the first to third carrier gas lines 51, 71, 91. While supplying the gas, the pressure is kept at a predetermined reduced pressure, and the temperature of the wafer W is controlled in the range of 400 to 500 ° C., for example, 450 ° C. Then, as in the first embodiment, the pressure in the gas storage tanks 42 and 62 is increased.

  In this state, for example, a TiN film is formed by ALD as shown in the gas supply sequence of FIG. 7 and the timing chart of FIG.

In this embodiment, steps S11 to S14 are performed corresponding to steps S1 to S4 of the first embodiment. Of steps S11 to S14, steps S11, S13, and S14 are basically performed in the same manner as steps S1, S3, and S4 of the first embodiment. However, in the TiCl ₄ gas purge step of step S12, other than purge gas. Is supplied with H ₂ gas. That is, in the present embodiment, the H ₂ gas is supplied both in step S12, which is a TiCl ₄ gas purge process, and in step S14, which is an NH ₃ gas purge process.

The flow rate of the H ₂ gas in steps S12 and S14 is preferably 200 to 30000 sccm, for example, 7000 sccm.

The flow rates of TiCl ₄ gas, NH ₃ gas, carrier gas, and purge gas are the same as those in the first embodiment, and the times of steps S11 to S14 are also the same as those in steps S1 to S4 of the first embodiment.

  By performing steps S11 to S14 as described above for a predetermined cycle of one cycle or more, a modified TiN film having a predetermined film thickness can be obtained.

The TiN film used for logic is required to form a very thin TiN film of 2 nm or less, further 1 nm or less by low-temperature film formation with high continuity as well as high coverage. However, the case of forming a TiN film by using a TiCl ₄ gas as the film forming material, since then if TiCl ₄ is electrically repel, TiCl ₄ is not adsorbed is described where suction originally in the base, the continuity of the film It becomes difficult to increase. On the other hand, by adding H ₂ gas, TiCl ₄ is reduced by the reaction of the following formulas (1) and (2), so that it is a monovalent ion (TiCl ₃ ) ⁺ or divalent. (TiCl ₂ ) ⁺⁺
2TiCl ₄ + H ₂ → 2 (TiCl ₃ ) ⁺ + 2HCl (1)
TiCl ₄ + H ₂ → (TiCl ₂ ) ⁺⁺ + 2HCl (2)
Since (TiCl ₃ ) ⁺ and (TiCl ₂ ) ⁺⁺ are activated by ionization, the adsorption power to the base is higher than that of TiCl ₄ , and a highly continuous TiN film can be obtained.

Also in the present embodiment, first and second purge gas lines 45 and 65 are provided separately from the first and second carrier gas lines 51 and 71 for supplying the carrier gas of TiCl ₄ gas and NH ₃ gas. The first and second purge gas lines 45 and 65 include valves V2 and V6 and flow rate adjusting units separately from the valves V3 and V7 and the flow rate adjusting units 52 and 72 of the first and second carrier gas lines 51 and 71, respectively. 47 and 67 are provided, the purge gas flow rate can be increased only during the purge, and there is no need to increase the carrier gas flow rate. For this reason, coverage (step coverage) can be improved without increasing and greatly increasing the flow rate of the TiCl ₄ gas, which is a raw material gas, and good coverage (step coverage) of 90% or more without reducing productivity. Can be obtained. In addition, since the treatment with H ₂ gas for enhancing the continuity of the film is performed at the time of purging after supplying the TiCl ₄ gas and after supplying the NH ₃ gas, the productivity by the H ₂ gas treatment is not affected. Almost no decrease in (throughput) occurs. Further, since the purge gas and the H ₂ gas can be supplied while reducing the carrier gas at the time of purging, the reforming by the H ₂ is performed in a short purge process by supplying a large flow rate of the H ₂ gas. Is possible.

Of course, also in this embodiment, the purge gas is supplied from the gas storage tanks 46 and 66 in a state where the pressure is increased, so that a larger flow rate, for example, a carrier gas flow rate, is entered into the processing container 11 (processing space 10). The purge gas can be supplied at a larger flow rate to purge the TiCl ₄ gas or NH ₃ gas in the processing vessel 11 in a short time. For this reason, the throughput can be further increased.

In the above example, the H ₂ gas is supplied in both the purge process after the TiCl ₄ gas supply and the purge process after the NH ₃ gas supply, but in this embodiment, the H ₂ gas is supplied only to the purge process after the TiCl ₄ gas supply. _Two gases may be supplied.

Next, the experimental results of this embodiment will be described.
First, a basic experiment was conducted to confirm the effect of H ₂ gas supply. Here, when the film forming temperature is set to 460 ° C. and the continuously supplied carrier gas N ₂ gas is used as a purge gas, when the TiN film is formed by ALD of TiCl ₄ gas and NH ₃ gas, H _{2 is used.} Was continuously supplied to confirm the effect of H ₂ gas. Here, the TiCl ₄ gas supply time was 0.05 sec, the TiCl ₄ gas purge time was 0.2 sec, the NH ₃ gas supply time was 0.3 sec, and the NH ₃ gas purge time was 0.3 sec.

  The continuity of the film was grasped using a Rough Ratio. Rough Ratio measures the film thickness of two layers of the Bulk layer and the Roughness layer shown in FIG. 9 by spectroscopic ellipsometry, and the thickness of the Roughness layer having a small density with respect to the total film thickness (Roughness layer + bulk layer). The ratio is shown.

FIG. 10 and FIG. 11 show the results of obtaining the Rough Ratio minimum film thickness by changing the H ₂ gas flow rate. FIG. 10 shows the relationship between the XRF film thickness on the horizontal axis and the Rough Ratio on the vertical axis. The Rough Ratio increases to a maximum value when nucleation starts from 0, and the continuity of the film increases at a portion where it gradually decreases. The Rough Ratio minimum film thickness, which is the film thickness at which the Rough Ratio has a minimum value, is one index indicating the degree of continuity. FIG. 11 is a diagram showing the relationship between the H ₂ gas flow rate and the Rough Ratio minimum film thickness, and the vertical axis indicates the amount of change in the Rough Ratio minimum film thickness based on the case where H ₂ gas is not supplied. As shown in these figures, it was confirmed that the Rough Ratio minimum film thickness decreased as the flow rate of H ₂ gas increased, and the continuity of the film was improved.

FIG. 12 is a diagram showing the relationship between the film thickness and the specific resistance at each H ₂ flow rate, and it was confirmed that the specific resistance decreases as the supply amount of H ₂ gas is increased.

Next, the film forming temperature is set to 460 ° C., N ₂ gas which is a continuously supplied carrier gas is used as a purge gas, and TiN film is added without adding H ₂ gas by ALD of TiCl ₄ gas and NH ₃ gas. case of forming (sample 1), in addition to the _{N 2} is continuously supplied carrier gas, _{N 2} is a purge gas is supplied during the purge, _{H 2} gas by ALD of TiCl ₄ gas and NH ₃ gas case of forming the TiN film without the addition of (sample 2), in addition to the N ₂ is continuously supplied carrier gas, N ₂ was supplied a purge gas during the purge, H at the time of the purge _{When a} TiN film was formed by supplying _two gases and ALD of TiCl ₄ gas and NH ₃ gas (sample 3), the Rough Ratio minimum film thickness was determined. Here, the TiCl ₄ gas supply time was 0.05 sec, the TiCl ₄ gas purge time was 0.2 sec, the NH ₃ gas supply time was 0.3 sec, and the NH ₃ gas purge time was 0.3 sec.

In Sample 1, the flow rate of TiCl ₄ gas was 50 sccm, the flow rate of NH ₃ gas was 2700 sccm, and the flow rate of N ₂ gas as a carrier gas was 3000 sccm. Sample 2, the flow rate of TiCl ₄ gas and 140 sccm, and 7000sccm flow rate of NH ₃ gas, the flow rate of _{N 2} gas as a carrier gas was respectively 3000 sccm, the flow rate of _{N 2} gas is a purge gas respectively was 9000 sccm. Sample 3 was the same as Sample 2 except that the flow rate of H ₂ gas was 10,000 sccm.

The result is shown in FIG. Using a carrier gas as a purge gas, a sample 1 without the addition of _{H 2} gas, and separately using a purge gas from the carrier gas, the sample 2 without addition of _{H 2} gas, Rough Ratio minimum thickness respectively 2.13Nm, 1. While it was 88 nm, Sample 3 to which H ₂ gas was added at the time of purging further reduced the Rough Ratio minimum film thickness to 1.8 nm. Thereby, in this embodiment, it was confirmed that the continuity of the film was improved.

<Third Embodiment>
Next, a third embodiment of the film forming method will be described.

In the film forming method according to this embodiment, the addition of H ₂ gas suppresses the etching of the TiN film itself by the TiCl ₄ gas, thereby achieving film thickness uniformity.

In order to obtain a TiN film having a low specific resistance, it may be required to form a TiN film at a high temperature of about 700 ° C., for example. At such a high temperature, in order to obtain a high step coverage, The flow rate of TiCl ₄ gas, which is a Ti raw material, needs to be a relatively large flow rate of 50 to 270 sccm, for example, 270 sccm.

However, when TiCl ₄ gas was supplied at a large flow rate, the thickness of the TiN film was reduced at the center, and a phenomenon that the in-plane uniformity of the film thickness deteriorated was observed. As a result of investigating the cause, TiCl ₄ gas is a gas with high etching properties. By supplying TiCl ₄ gas at a large flow rate as described above, the etching of the TiN film itself formed by TiCl ₄ gas proceeds. It has been found that the etching effect is increased at the center of the wafer W.

Actually, using the apparatus shown in FIG. 1, a TiN film was formed under the conditions of temperature: 700 ° C., pressure: 5 Torr (666 Pa), TiCl ₄ gas flow rate: 50 sccm, NH ₃ gas flow rate: 3500 sccm, and then TiCl ₄ at 700 ° C. The TiN film was etched by changing the gas flow rate to 50 sccm, 80 sccm, 180 sccm, and 270 sccm, repeating the cycle of TiCl ₄ gas supply for 0.05 sec and purge (N ₂ gas flow rate: 7000 sccm for each line) for 0.8 sec for 300 cycles. The result is shown in FIG. FIG. 14 is a diagram showing the relationship between the position in the wafer radial direction and the etching amount of the TiN film at each TiCl ₄ flow rate. As shown in this figure, it was confirmed that as the flow rate of the TiCl ₄ gas increased, the etching amount increased and the central part was etched much. Therefore, TiCl ₄ deterioration of film thickness in-plane uniformity when the gas flow rate was large flow rate of is considered to be the influence of the etching of the TiCl ₄ gas.

Next, after forming a TiN film under the same conditions, the flow rate of TiCl ₄ gas during etching is fixed at 270 sccm, the temperature is changed to 400 ° C., 500 ° C., 600 ° C., and 700 ° C., and the same etching cycle is performed. The etching amount was confirmed after 300 cycles. FIG. 15 is a diagram showing the relationship between the position in the wafer radial direction and the etching amount of the TiN film at that time. From this figure, it was confirmed that etching was significant only at 700 ° C., and etching did not occur up to 600 ° C., but rather increased.

Next, a TiN film was formed under the same conditions except that the apparatus configuration was partially changed, and the flow rate of TiCl ₄ gas during etching was fixed at 270 sccm, and the temperatures were 625 ° C., 650 ° C., 675 ° C., 700 ° C. The amount of etching was confirmed by performing 300 similar etching cycles. FIG. 16 is a diagram showing the relationship between the position in the wafer radial direction and the etching amount of the TiN film at that time. From this figure, it can be seen that the effect of etching with TiCl ₄ gas occurs from 625 ° C. and increases as the temperature increases.

Next, after forming a TiN film under the same conditions using the same apparatus as in FIG. 16, the temperature is 700 ° C., the flow rate of TiCl ₄ gas is 270 sccm, and the above-described etching cycle is 100 cycles, 200 cycles. The etching amount when changed to 300 cycles was confirmed. FIG. 17 is a diagram showing the relationship between the position in the wafer radial direction and the etching amount of the TiN film at that time. From this figure, it can be seen that the influence of etching with TiCl ₄ gas is small when the number of cycles is small, but increases as the number of cycles increases.

In the present embodiment, the etching action associated with the increase in the TiCl ₄ gas flow rate is suppressed by adding H ₂ gas.

The experimental results confirming this will be described.
Here, after using the same apparatus as in FIG. 16 to form a TiN film under the same conditions, the temperature: 700 ° C., the flow rate of TiCl ₄ gas: 270 sccm, TiCl ₄ gas supply 0.05 sec, purge (N ₍₂ gas flow rate: 7000 sccm for each line) When the TiN film is etched by repeating a cycle of 0.8 sec for 300 cycles (no addition of H ₂ when forming the TiN film) and N ₂ gas (flow rate: each line) The TiN film was formed under the same conditions except that H ₂ gas (flow rate: 7000 sccm) was further added to 7000 sccm). Temperature: 700 ° C., TiCl ₄ gas flow rate: 270 sccm, TiCl ₄ gas supply 0.05 sec purge: T is repeated 300 cycles of the _{(N 2} gas flow rate each line 7000sccm) 0.85sec If the N film is etched for (there added when H ₂ TiN film formation), and confirmed the etching amount. FIG. 18 is a diagram showing the relationship between the position in the wafer radial direction and the etching amount of the TiN film at that time. From this figure, it was confirmed that the etching of the TiN film can be suppressed by adding H ₂ gas when forming the TiN film.

Based on the above experimental results, in the present embodiment, preferably, the temperature is 625 ° C. or higher and the TiCl ₄ gas flow rate is 50 to 270 sccm, in the same sequence as in the first embodiment or the second embodiment. A TiN film is formed by adding H ₂ gas.

Specifically, first, similarly to the first and second embodiments, the valves V1 to V9 are closed and the gate valve 13 is opened in a state where the mounting table 21 is lowered to the delivery position (not shown). The wafer W is loaded into the processing container 11 from the vacuum transfer chamber (not shown) via the loading / unloading port 12 and placed on the lift pins 20, the transfer device is retracted, and the gate valve 13 is closed. Then, the wafer W is placed on the mounting table 21 by raising the mounting table 21 to the processing position. In the present embodiment, the mounting table 21 is heated to a range of 625 to 740 ° C. by the heater 22. Then, the valves V3, V7, V9 are opened, and the carrier N _{2 is} supplied from the first to third carrier gas supply sources 53, 73, 93 into the processing container 11 via the first to third carrier gas lines 51, 71, 91. While supplying a gas, the pressure is kept at a predetermined reduced pressure, and the temperature of the wafer W is controlled in a range of 625 to 740 ° C., for example, 700 ° C. Then, as in the first and second embodiments, the pressure in the gas storage tanks 42 and 62 is increased.

In this state, for example, by ALD as shown in the gas supply sequence of FIG. 2 and the timing chart of FIG. 3 in the first embodiment, or the gas supply sequence of FIG. 7 and the timing chart of FIG. 8 in the second embodiment. A TiN film is formed. That is, in this embodiment, TiN ₄ gas supply, TiCl ₄ gas purge, NH ₃ gas supply, and NH ₃ gas purge are repeated to form a TiN film having a predetermined thickness. ₃ to only purge step after the gas supply may be carried out the supply of H ₂ gas may be supplied H ₂ gas in both purge step after TiCl ₄ after the gas supply and the NH ₃ gas supply.

At this time, the flow rate of the H ₂ gas is preferably 200 to 30000 sccm, for example, 7000 sccm.

The flow rates of TiCl ₄ gas, NH ₃ gas, carrier gas, and purge gas are the same as those in the first embodiment and the second embodiment, and the time of these processes is also step S1 of the first embodiment and the second embodiment. To S4 and steps S11 to S14.

In the present embodiment, even when the film formation temperature is high and the TiCl ₄ gas flow rate is large, the etching action of the TiCl ₄ gas is suppressed by supplying H ₂ gas at the time of purging by the above process. Therefore, it is possible to obtain a highly covering film while ensuring high productivity and to make the thickness of the TiN film uniform.

<Other applications>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be variously modified within the scope of the technical idea of the present invention.

For example, in the above embodiment, the case where the TiN film is formed using TiCl ₄ gas as the source gas and NH ₃ gas as the reaction gas has been described, but the Ti source gas and the reaction gas are not limited to this. .

In the above embodiment, the case where the TiN film is formed with the Ti source gas and the nitriding gas as the reaction gas has been described. However, the film to be formed is particularly suitable if it is formed by the source gas and the reaction gas. The present invention is not limited, and can be applied to the formation of various films such as a WN film, a W film, a TiON film, a SiN film, and a SiO ₂ film.

Furthermore, in the present embodiment, an example in which N ₂ gas is used as an inert gas used as a carrier gas or a purge gas has been described. However, the present invention is not limited to N ₂ gas, but other inert gases such as a rare gas such as Ar gas and He gas. An active gas may be used.

Furthermore, in the above-described embodiment, the example in which H ₂ gas is used as the additive gas having the function of reducing the specific resistance with respect to the TiN film and the function of improving the continuity of the film has been described. As long as it is an additive gas that has a predetermined function, various gases such as O ₂ gas, NH ₃ gas, BCl ₃ gas, SiH ₄ gas, and SiH ₂ Cl ₂ gas are used without being limited to H ₂ gas. be able to.

1; film forming apparatus 2; gas supply mechanism 10; processing space 11; the processing vessel 17; an exhaust duct 21; mounting table 34; an exhaust pipe 37; a vacuum pump 41; TiCl ₄ gas lines 42,46,62,66,82; Gas storage tank 44; TiCl ₄ gas supply source 45, 65; purge gas line 48, 68; purge gas supply source 51, 71, 91; carrier gas line 53, 73; carrier gas supply source 61; NH ₃ gas line 64; NH ₃ Gas supply source 81; H ₂ gas line 84; H ₂ gas supply source 100; controller V1 to V9; valve W; semiconductor wafer

Claims (13)

A processing container in which a substrate to be processed is stored;
A gas supply mechanism for supplying a source gas and a reaction gas for forming a predetermined film on the substrate to be processed, a carrier gas for conveying these to the processing container, and a purge gas for purging the inside of the processing container;
An exhaust mechanism for exhausting the inside of the processing container and maintaining the inside of the processing container in a vacuum atmosphere;
The gas supply mechanism includes a source gas flow path for supplying the source gas into the processing container,
A reaction gas flow path for supplying the reaction gas into the processing container;
A first carrier gas channel and a second carrier gas channel connected to the source gas channel and the reaction gas channel, respectively, for supplying the source gas and a carrier gas of the reaction gas;
The first carrier gas flow path and the second carrier gas flow path are provided separately, and a purge gas for purging the inside of the processing container is separated from the first carrier gas and the second carrier gas. A purge gas passage for controlling the flow rate to be supplied into the processing vessel,
An additive gas flow path for supplying an additive gas having a predetermined function to the predetermined film;
A film forming apparatus having an open / close valve that independently opens and closes the source gas flow path, the reaction gas flow path, the first and second carrier gas flow paths, the purge gas flow path, and the additive gas flow path A film forming method for forming the predetermined film using
With the substrate to be processed disposed in the processing container,
A first step of constantly supplying a carrier gas into the processing container via the first carrier gas channel and the second carrier gas channel;
A second step of supplying the source gas into the processing vessel via the source gas flow path and adsorbing the source gas on the surface of the substrate to be processed;
A third step of stopping the supply of the source gas and supplying the purge gas into the processing vessel via the purge gas flow path to purge the source gas;
A fourth step of supplying the reaction gas into the processing container via the reaction gas flow path to react the source gas and the reaction gas;
A fifth step of stopping the supply of the reaction gas and supplying the purge gas into the processing container through the purge gas flow path to purge the reaction gas, and the steps from the second step to the fifth step are predetermined. Cycle run,
The additive gas having the predetermined function as the at least part of the purge gas through the additive gas flow path in one or both of the third step of purging the source gas and the fifth step of purging the reaction gas A film forming method characterized by supplying   The purge gas channel has a gas reservoir for storing the purge gas. After the purge gas is stored in the gas reservoir and the pressure in the gas reservoir is increased, the valve provided in the purge gas channel is opened. 2. The film forming method according to claim 1, wherein the purge gas is supplied to the processing container.   The purge gas channel has a first purge gas channel connected to the source gas channel and a second purge gas channel connected to the reaction gas channel, and purges the source gas. The purge gas is supplied through the first purge gas channel and the second purge gas channel in the third step and the fifth step of purging the reaction gas. 2. The film forming method according to 2. 4. The composition according to claim 1, wherein the source gas is TiCl ₄ gas, the reaction gas is NH ₃ gas, and the predetermined film is a TiN film. Membrane method. The film forming method according to claim 4, wherein the additive gas is H ₂ gas. The temperature at the time of film formation is 400 to 750 ° C., and H ₂ gas as the additive gas is supplied during the fifth step of purging the reaction gas, and the H ₂ gas has a specific resistance of the TiN film. The film forming method according to claim 5, wherein the film forming method has a function of lowering.   The film forming method according to claim 6, wherein the second process to the fifth process are repeated a plurality of cycles, and the time of the fifth process in the final cycle is lengthened.   The film forming method according to claim 6, wherein the second step to the fifth step are repeated a plurality of cycles, and the fifth step is periodically lengthened. The temperature at the time of film formation is 400 to 500 ° C., and the H ₂ gas as the additive gas is supplied during both the third step of purging the source gas and the fifth step of purging the reaction gas, The film forming method according to claim 5, wherein the H ₂ gas has a function of improving the continuity of the TiN film. The H ₂ gas as the additive gas is supplied only during the fifth step of purging the reaction gas, or during both the third step of purging the source gas and the fifth step of purging the reaction gas, The film forming method according to claim 5, wherein the H ₂ gas has a function of suppressing an etching action of TiCl ₄ .   The temperature at the time of film-forming is the range of 625-740 degreeC, The film-forming method of Claim 10 characterized by the above-mentioned. The film forming method according to claim 10 or 11, wherein a flow rate of the TiCl ₄ gas is in a range of 50 to 270 sccm. A processing container in which a substrate to be processed is stored;
A gas supply mechanism for supplying a source gas and a reaction gas for forming a predetermined film on the substrate to be processed, a carrier gas for conveying these to the processing container, and a purge gas for purging the inside of the processing container;
An exhaust mechanism for exhausting the inside of the processing container and maintaining the inside of the processing container in a vacuum atmosphere;
A control unit for controlling the gas supply mechanism and the exhaust mechanism;
The gas supply mechanism includes a source gas flow path for supplying the source gas into the processing container,
A reaction gas flow path for supplying the reaction gas into the processing container;
A first carrier gas channel and a second carrier gas channel connected to the source gas channel and the reaction gas channel, respectively, for supplying the source gas and a carrier gas of the reaction gas;
The first carrier gas flow path and the second carrier gas flow path are provided separately, and a purge gas for purging the inside of the processing container is separated from the first carrier gas and the second carrier gas. A purge gas passage for controlling the flow rate to be supplied into the processing vessel,
An additive gas flow path for supplying an additive gas having a predetermined function to the predetermined film;
An open / close valve that independently opens and closes the source gas channel, the reaction gas channel, the first and second carrier gas channels, the purge gas channel, and the additive gas channel,
The controller is
With the substrate to be processed disposed in the processing container,
A first step of constantly supplying a carrier gas into the processing container via the first carrier gas channel and the second carrier gas channel;
A second step of supplying the source gas into the processing vessel via the source gas flow path and adsorbing the source gas on the surface of the substrate to be processed;
A third step of stopping the supply of the source gas and supplying the purge gas into the processing vessel via the purge gas flow path to purge the source gas;
A fourth step of supplying the reaction gas into the processing container via the reaction gas flow path to react the source gas and the reaction gas;
A fifth step of stopping the supply of the reaction gas and supplying the purge gas into the processing container through the purge gas flow path to purge the reaction gas, and the steps from the second step to the fifth step are predetermined. Cycle run,
The additive gas having the predetermined function via the additive gas flow path as at least a part of the purge gas in one or both of the third step of purging the source gas and the fifth step of purging the reaction gas The film formation apparatus is controlled to supply the film.

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