WO2021215270A1

WO2021215270A1 - Film formation mehtod

Info

Publication number: WO2021215270A1
Application number: PCT/JP2021/015018
Authority: WO
Inventors: 裕布重; 敦史田中
Original assignee: 東京エレクトロン株式会社
Priority date: 2020-04-22
Filing date: 2021-04-09
Publication date: 2021-10-28
Also published as: JP2021172841A

Abstract

A film formation method according to an embodiment of the present disclosure forms a film including at least three elements, the method having a step for supplying a first reaction gas including a first element into a processing container, a step for purging the first reaction gas, a step for supplying a second reaction gas including a second element that reacts with the first reaction gas into the processing container, and a step for purging the second reaction gas, a third reaction gas including a third element being supplied into the reaction container in at least one of the step for purging the first reaction gas and the step for purging the second reaction gas.

Description

Film formation method

This disclosure relates to a film forming method.

A technique is known in which a TiCl ₄ supply, a purge, an NH ₃ supply, a purge, an O ₂ supply, and a purge are set as one cycle, and a titanium oxynitride film having a predetermined film thickness is formed on a wafer by using the ALD method. For example, see Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-172171

The present disclosure provides a technique capable of both improving productivity and improving the uniformity of element concentration in the film thickness direction.

The film forming method according to one aspect of the present disclosure is a film forming method of a film containing at least three elements, which comprises a step of supplying a first reaction gas containing the first element into a processing container and the first reaction gas. A step of purging the reaction gas, a step of supplying a second reaction gas containing a second element that reacts with the first reaction gas into the processing container, and a step of purging the second reaction gas. And, in at least one of the step of purging the first reaction gas and the step of purging the second reaction gas, a third reaction gas containing the third element is supplied into the processing container. do.

According to the present disclosure, both improvement in productivity and improvement in uniformity of element concentration in the film thickness direction can be achieved at the same time.

Flow chart showing an example of the film forming method of the embodiment Schematic diagram showing an example of the film forming apparatus of the embodiment The figure which shows an example of the gas supply sequence of the film formation method of embodiment The figure which shows another example of the gas supply sequence of the film formation method of embodiment The figure which shows still another example of the gas supply sequence of the film formation method of embodiment The figure which shows still another example of the gas supply sequence of the film formation method of embodiment The figure which shows the relationship between the number of cycles and the film thickness The figure which shows the relationship between the oxygen supply time and the oxygen concentration in a membrane The figure which shows the relationship between the oxygen flow rate and the oxygen concentration in a membrane when the substrate temperature is constant. The figure which shows the relationship between the oxygen flow rate and the oxygen concentration in a membrane when the substrate temperature is changed.

Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the attached drawings, the same or corresponding members or parts are designated by the same or corresponding reference numerals, and duplicate description is omitted.

[Film film method]
With reference to FIG. 1, the film forming method of the embodiment will be described by taking as an example a case where a titanium oxynitride (TiON) film is formed on a substrate by an atomic layer deposition (ALD) method. .. FIG. 1 is a flowchart showing an example of the film forming method of the embodiment.

First, the substrate is housed in the processing container, the inside of the processing container is kept in a reduced pressure (vacuum) state, and the substrate is adjusted to a predetermined temperature. The substrate may be a semiconductor wafer such as a silicon wafer.

_{Subsequently, by supplying titanium tetrachloride (TiCl 4} ) gas, which is a Ti-containing gas, into the processing container in which the substrate is housed _{, the TiCl 4} gas is adsorbed on the substrate (step S1). _{In this embodiment, TiCl 4} gas is used as the Ti-containing gas, but for example, tetrakis dimethylamino titanium (TDMAT) gas or tetrakis ethyl methyl amino titanium (TEMAT) gas may be used.

_{Subsequently, the TiCl 4} gas remaining in the processing container _{is purged by supplying nitrogen (N 2} ) gas, which is an inert gas, into the processing container (step S2). At this time, _{oxygen (O 2} ) gas, which is an oxygen-containing gas, is _{supplied together with N 2 gas.} As a result, a part of _{the TiCl 4 gas adsorbed on the substrate is oxidized.} The O ₂ gas may be supplied into the processing container during the entire period of step S2, or may be supplied into the processing container during a part of the period of step S2. By O ₂ to adjust the flow rate of the period and the O ₂ gas supplied to the gas, it is possible to control the amount of oxidizing TiCl ₄ gas. In other words, the oxygen concentration in the film-formed TiON film can be controlled. In the present embodiment, N ₂ gas is used as the inert gas, but for example, argon (Ar) gas may be used. _{Further, although O 2} gas is used as the oxygen-containing gas, for example, ozone (O ₃ ) gas may be used.

_{Subsequently, by supplying ammonia (NH 3} ) gas, which is a nitrogen-containing gas, into the processing container, _{the TiCl 4} gas adsorbed on the substrate is nitrided (step S3). _{Although NH 3} gas is used as the nitrogen-containing gas in this embodiment, for example, hydrazine (N ₂ H ₄ ) gas or monomethylhydrazine (MMH) gas may be used.

_{Subsequently, the NH 3} gas remaining in the processing container _{is purged by supplying the N 2} gas, which is an inert gas, into the processing container (step S4). At this time, _{O 2} gas, which is an oxygen-containing gas, is _{supplied together with N 2 gas.} As a result, a part of _{the TiCl 4 gas adsorbed on the substrate is oxidized.} The O ₂ gas may be supplied into the processing container during the entire period of step S4, or may be supplied into the processing container during a part of the period of step S4. In the present embodiment, N ₂ gas is used as the inert gas, but Ar gas may be used, for example. _{Further, although O 2} gas is used as the oxygen-containing gas, for example, O ₃ gas may be used.

Subsequently, it is determined whether or not the number of executions of steps S1 to S4 has reached a predetermined number of times X (X is an integer of 1 or more) (step S5). In step S5, if the number of executions of steps S1 to S4 has not reached the number X, the process returns to step S1 and steps S1 to S4 are executed again. In step S5, when the number of executions of steps S1 to S4 reaches the number X, the process ends. By repeating steps S1 to S4 in this way until the number of times X is reached, a TiON film having a predetermined film thickness is formed on the substrate.

In the example shown in FIG. 1, the case where the O ₂ gas is supplied into the processing container in steps S2 and S4 has been described, but the present disclosure is not limited to this, and in either step S2 or step S4. _{O 2} gas may be supplied into the processing container. _{That is, the O 2} gas may be supplied into the processing container in step S2, _{and the O 2} gas may not be supplied into the processing container in step S4. _{Further, the O 2} gas may be supplied into the processing container in step S4, _{and the O 2} gas may not be supplied into the processing container in step S2.

According to the film forming method of the embodiment described above, TiON is supplied by supplying _{O 2} gas into the processing container in at least one of step S2 for purging the _{TiCl 4} _{gas and step S4 for purging the NH 3 gas.} A film is formed. As a result, the number of steps can be reduced as compared with the case of forming the TiON film by performing the step of supplying the _{O 2} gas separately from the steps S1 to S4, and the time equivalent to the case of forming the TiN film can be reduced. A TiON film can be formed. Further, since the O ₂ gas is supplied in all the cycles, the uniformity of the oxygen concentration in the film thickness direction is improved. That is, both the improvement of productivity and the improvement of the uniformity of oxygen concentration in the film thickness direction can be achieved at the same time.

On the other hand, when a TiCl ₄ supply, a purge, an NH ₃ supply, a purge, an O ₂ supply, and a purge are set as one cycle and a TiON film having a predetermined film thickness is formed on the substrate by the ALD method, the O ₂ supply is performed. And since the number of steps is increased by the amount of purging, the film forming time becomes long. Further, _{when a TiON film is formed by supplying O 2} _{every time the cycle of TiCl 4} supply, purge, NH ₃ supply, and purge is repeated a plurality of times, the oxygen concentration in the film thickness direction tends to be distributed, and the film is likely to be distributed. It is difficult to adjust the oxygen concentration in the thick direction.

[Film formation device]
An example of a film forming apparatus for carrying out the above-mentioned film forming method for a TiON film will be described with reference to FIG. FIG. 2 is a schematic view showing an example of the film forming apparatus of the embodiment.

The film forming apparatus includes a processing container 1, a mounting table 2, a shower head 3, an exhaust unit 4, a gas supply unit 5, and a control unit 6.

The processing container 1 is made of a metal such as aluminum and has a substantially cylindrical shape. The processing container 1 accommodates a semiconductor wafer (hereinafter referred to as “wafer W”), which is an example of a substrate. A carry-in outlet 11 for carrying in or out the wafer W is formed on the side wall of the processing container 1. The carry-in outlet 11 is opened and closed by the gate valve 12. An annular exhaust duct 13 having a rectangular cross section is provided on the main body of the processing container 1. A slit 13a is formed in the exhaust duct 13 along the inner peripheral surface. An exhaust port 13b is formed on the outer wall of the exhaust duct 13. A top wall 14 is provided on the upper surface of the exhaust duct 13 so as to close the upper opening of the processing container 1. The exhaust duct 13 and the top wall 14 are hermetically sealed with a seal ring 15.

The mounting table 2 horizontally supports the wafer W in the processing container 1. The mounting table 2 has a disk shape larger than that of the wafer W, and is made of a ceramic material such as aluminum nitride (AlN) or a metal material such as aluminum or nickel alloy. A heater 21 for heating the wafer W is embedded in the mounting table 2. The heater 21 is supplied with power from a heater power source (not shown) to generate heat. Then, the wafer W is controlled to a predetermined temperature by controlling the output of the heater 21 by a temperature signal of a thermocouple (not shown) provided near the upper surface of the mounting table 2. The mounting table 2 is provided with a cover member 22 formed of ceramics such as alumina so as to cover the outer peripheral region of the upper surface and the side surface.

The mounting table 2 is supported by the support member 23. The support member 23 extends from the center of the bottom surface of the mounting table 2 to the lower side of the processing container 1 through a hole formed in the bottom wall of the processing container 1, and the lower end thereof is connected to the elevating mechanism 24. The mounting table 2 is moved up and down by the elevating mechanism 24 between the processing position shown in FIG. 1 and the transfer position where the wafer W can be conveyed, which is indicated by the alternate long and short dash line below the processing position. A collar portion 25 is attached below the processing container 1 of the support member 23. A bellows 26 is provided between the bottom surface of the processing container 1 and the collar portion 25. The bellows 26 separates the atmosphere inside the processing container 1 from the outside air, and expands and contracts as the mounting table 2 moves up and down.

Near the bottom surface of the processing container 1, three wafer support pins 27 (only two are shown) are provided so as to project upward from the elevating plate 27a. The wafer support pin 27 is moved up and down via the lifting plate 27a by the lifting mechanism 28 provided below the processing container 1. The wafer support pin 27 is inserted into a through hole 2a provided in the mounting table 2 at the transport position so that the wafer support pin 27 can be recessed with respect to the upper surface of the mounting table 2. By raising and lowering the wafer support pin 27, the wafer W is transferred between the transfer robot (not shown) and the mounting table 2.

The shower head 3 supplies the processing gas into the processing container 1 in the form of a shower. The shower head 3 is made of, for example, a metal material and is arranged so as to face the mounting table 2. The shower head 3 has substantially the same diameter as the mounting table 2. The shower head 3 includes a main body 31 and a shower plate 32. The main body 31 is fixed to the lower surface of the top wall 14. The shower plate 32 is connected under the main body 31. A gas diffusion space 33 is formed between the main body 31 and the shower plate 32. The gas diffusion space 33 is provided with gas introduction holes 36 and 37 so as to penetrate the center of the top wall 14 and the main body 31. An annular protrusion 34 projecting downward is formed on the peripheral edge of the shower plate 32. A large number of gas discharge holes 35 are formed on the flat surface inside the annular protrusion 34 of the shower plate 32.

When the mounting table 2 is present at the processing position, a processing space 38 is formed between the mounting table 2 and the shower plate 32, and the upper surface of the cover member 22 and the annular protrusion 34 are close to each other to form an annular gap 39. Will be done.

The exhaust unit 4 exhausts the inside of the processing container 1. The exhaust unit 4 includes an exhaust pipe 41 and an exhaust mechanism 42. The exhaust pipe 41 is connected to the exhaust port 13b. The exhaust mechanism 42 is connected to the exhaust pipe 41 and includes a vacuum pump, a pressure control valve, and the like. The exhaust mechanism 42 exhausts the gas in the processing container 1 through the exhaust duct 13 and the exhaust pipe 41.

The gas supply unit 5 supplies various gases to the shower head 3. The gas supply unit 5 includes a TiCl ₄ supply source 51a, an NH ₃ supply source 52a, an N ₂ supply source 53a, an N ₂ supply source 54a, an O ₂ supply source 55a, an NH ₃ supply source 56a, an N ₂ supply source 57a and an N ₂ It has a source 58a.

The TiCl ₄ _{supply source 51a supplies the TiCl 4} gas, which is an example of the Ti-containing gas, into the processing container 1 via the gas supply line 51b. A flow rate controller 51c, a storage tank 51d, and a valve 51e are interposed in the gas supply line 51b from the upstream side. The downstream side of the valve 51e of the gas supply line 51b is connected to the gas introduction hole 37. TiCl ₄ TiCl ₄ gas supplied from the supply source 51a is temporarily stored in the storage tank 51d before being supplied into the processing container 1, after being raised to a predetermined pressure in the storage tank 51d, into the processing vessel 1 Be supplied. _{The supply and stop of the TiCl 4} gas from the storage tank 51d to the processing container 1 is performed by the valve 51e. By temporarily storing the _{TiCl 4} gas in the storage tank 51d in this way _{, the TiCl 4} gas can be stably supplied into the processing container 1 at a relatively large flow rate.

The NH ₃ _{supply source 52a supplies NH 3} gas, which is an example of nitrogen-containing gas, into the processing container 1 via the gas supply line 52b. A flow rate controller 52c, a storage tank 52d, and a valve 52e are interposed in the gas supply line 52b from the upstream side. The downstream side of the valve 52e of the gas supply line 52b is connected to the gas supply line 51b. NH ₃ gas supplied from the NH ₃ supply source 52a is temporarily stored in the storage tank 52d before being supplied into the processing container 1, after being raised to a predetermined pressure in the storage tank 52d, into the processing vessel 1 Be supplied. Supply and stop of the NH ₃ gas from the storage tank 52d to the processing chamber 1 is performed by the valve 52e. By temporarily storing the _{NH 3} gas in the storage tank 52d in this way _{, the NH 3} gas can be stably supplied into the processing container 1 at a relatively large flow rate.

The N ₂ _{supply source 53a supplies N 2} gas, which is an example of purge gas, into the processing container 1 via the gas supply line 53b. A flow rate controller 53c, a storage tank 53d, and a valve 53e are interposed in the gas supply line 53b from the upstream side. The downstream side of the valve 53e of the gas supply line 53b is connected to the gas supply line 51b. N ₂ gas supplied from the N ₂ supply source 53a is temporarily stored in the storage tank 53d before being supplied into the processing container 1, after being raised to a predetermined pressure in the storage tank 53d, into the processing vessel 1 Be supplied. Supply and stop of the _{N 2} gas from the storage tank 53d to the processing chamber 1 is performed by the valve 53e. By temporarily storing the _{N 2} gas in the storage tank 53d in this way _{, the N 2} gas can be stably supplied into the processing container 1 at a relatively large flow rate.

The N ₂ _{supply source 54a supplies the N 2} gas, which is an example of the carrier gas, into the processing container 1 via the gas supply line 54b. A flow rate controller 54c, a valve 54e, and an orifice 54f are interposed in the gas supply line 54b from the upstream side. The downstream side of the orifice 54f of the gas supply line 54b is connected to the gas supply line 51b. N ₂ gas supplied from the N ₂ supply source 54a is supplied into the processing vessel 1 continuously during deposition of the wafer W. _{The supply and stop of the N 2} gas from the N ₂ supply source 54a to the processing container 1 is performed by the valve 54e. Orifice 54f inhibits

storage tank

51d, 52 d, gas supply line 51b by 53d, 52 b, that a relatively large flow rate of gas supplied to 53b from flowing back to the _{N 2} gas supply line 54b.

The O ₂ _{supply source 55a supplies the O 2} gas, which is an example of the oxygen-containing gas, into the processing container 1 via the gas supply line 55b. A flow rate controller 55c, a storage tank 55d, and a valve 55e are interposed in the gas supply line 55b from the upstream side. The downstream side of the valve 55e of the gas supply line 55b is connected to the gas introduction hole 36. O ₂ O ₂ gas supplied from the supply source 55a is temporarily stored in the storage tank 55d before being supplied into the processing container 1, after being raised to a predetermined pressure in the storage tank 55d, into the processing vessel 1 Be supplied. _{The supply and stop of the O 2} gas from the storage tank 55d to the processing container 1 is performed by the valve 55e. By temporarily storing the _{O 2} gas in the storage tank 55d in this way _{, the O 2} gas can be stably supplied into the processing container 1 at a relatively large flow rate.

The NH ₃ _{supply source 56a supplies NH 3} gas, which is an example of nitrogen-containing gas, into the processing container 1 via the gas supply line 56b. A flow rate controller 56c, a storage tank 56d, and a valve 56e are interposed in the gas supply line 56b from the upstream side. The downstream side of the valve 56e of the gas supply line 56b is connected to the gas supply line 55b. NH ₃ gas supplied from the NH ₃ supply source 56a is temporarily stored in the storage tank 56d before being supplied into the processing container 1, after being raised to a predetermined pressure in the storage tank 56d, into the processing vessel 1 Be supplied. Supply and stop of the NH ₃ gas from the storage tank 56d to the processing chamber 1 is performed by the valve 56e. By temporarily storing the _{NH 3} gas in the storage tank 56d in this way _{, the NH 3} gas can be stably supplied into the processing container 1 at a relatively large flow rate.

The N ₂ _{supply source 57a supplies N 2} gas, which is an example of purge gas, into the processing container 1 via the gas supply line 57b. A flow rate controller 57c, a storage tank 57d, and a valve 57e are interposed in the gas supply line 57b from the upstream side. The downstream side of the valve 57e of the gas supply line 57b is connected to the gas supply line 55b. N ₂ gas supplied from the N ₂ supply source 57a is temporarily stored in the storage tank 57d before being supplied into the processing container 1, after being raised to a predetermined pressure in the storage tank 57d, into the processing vessel 1 Be supplied. Supply and stop of the _{N 2} gas from the storage tank 57d to the processing chamber 1 is performed by the valve 57e. By temporarily storing the _{N 2} gas in the storage tank 57d in this way _{, the N 2} gas can be stably supplied into the processing container 1 at a relatively large flow rate.

The N ₂ _{supply source 58a supplies N 2} gas, which is an example of carrier gas, into the processing container 1 via the gas supply line 58b. A flow rate controller 58c, a valve 58e, and an orifice 58f are interposed in the gas supply line 58b from the upstream side. The downstream side of the orifice 58f of the gas supply line 58b is connected to the gas supply line 55b. N ₂ gas supplied from the N ₂ supply source 58a is supplied into the processing vessel 1 continuously during deposition of the wafer W. _{The supply and stop of the N 2} gas from the N ₂ supply source 58a to the processing container 1 is performed by the valve 58e. The orifice 58f suppresses the backflow of a relatively large flow rate of gas supplied to the gas supply lines 55b, 56b, 57b by the

storage tanks

55d, 56d, 57d to the gas supply line 58b.

The control unit 6 is, for example, a computer, and includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an auxiliary storage device, and the like. The CPU operates based on a program stored in the ROM or the auxiliary storage device, and controls the operation of the film forming apparatus. The control unit 6 may be provided inside the film forming apparatus or may be provided outside. When the control unit 6 is provided outside the film forming apparatus, the control unit 6 can control the film forming apparatus by a communication network such as wired or wireless.

[Operation of film forming equipment]
An example of a method of forming a TiON film on the wafer W by using the above-mentioned film forming apparatus will be described with reference to FIGS. 2 and 3. Figure 3 is a diagram showing an example of a gas supply sequence of the film-forming method of the embodiment, by supplying O ₂ gas into the processing vessel 1 at step S2, the supply of O ₂ gas into the processing chamber 1 in the step S4 The gas supply sequence when not is shown.

First, with the valves 51e to 58e closed, the gate valve 12 is opened, the wafer W is conveyed into the processing container 1 by a transfer robot (not shown), and the wafer W is placed on the mounting table 2 at the transfer position. .. After retracting the transfer robot from the processing container 1, the gate valve 12 is closed. The wafer W is heated to a predetermined temperature (for example, 300 ° C. to 700 ° C.) by the heater 21 of the mounting table 2, and the mounting table 2 is raised to the processing position to form the processing space 38. Further, the pressure control valve of the exhaust mechanism 42 adjusts the inside of the processing container 1 to a predetermined pressure (for example, 200 Pa to 1200 Pa).

Next, the

valves

54e and 58e are opened to supply a predetermined flow rate (for example, 300 sccm to 10000 sccm) of carrier gas (N ₂ gas) _{from the N 2 supply sources 54a and 58a to the gas supply lines 54b and 58b, respectively.} Further, TiCl ₄ source 51a, NH ₃ source 52a, _{O 2} supply source 55a and the NH ₃ supply source 56a respectively from TiCl ₄ gas, NH ₃ gas, _{O 2} gas and NH ₃ gas of the

gas supply line

51b, 52 b, It is supplied to 55b and 56b. At this time, since the

valves

51e, 52e, 55e, and 56e are closed, the TiCl ₄ gas, NH ₃ gas, O ₂ gas, and NH ₃ gas are stored in the

storage tanks

51d, 52d, 55d, and 56d, respectively, and stored. The pressure inside the

tanks

51d, 52d, 55d, and 56d is increased.

Next, the valve 51e is opened, and the TiCl ₄ gas stored in the storage tank 51d is supplied into the processing container 1 and adsorbed on the wafer W (step S1). Further, in parallel with the supply _{of the TiCl 4} gas into the processing container 1, the _{purge gas (N 2} gas) is supplied _{from the N 2}

supply sources

53a and 57a to the gas supply lines 53b and 57b, respectively. At this time, since the valves 53e and 57e are closed, the purge gas is stored in the

storage tanks

53d and 57d, and the pressure inside the 53d and 57d is increased.

After a predetermined time (for example, 0.03 to 3.0 seconds) has elapsed from opening the valve 51e, the valve 51e is closed and the

valves

53e, 57e, 55e are opened. _{As a result, the supply of TiCl 4} gas into the processing container 1 is stopped, and the purge gas stored in the

storage tanks

53d and 57d and the O ₂ gas stored in the storage tank 55d are supplied into the processing container 1 ( Step S2). At this time, since the gas is supplied from the

storage tanks

53d and 57d in the state where the pressure is increased, the purge gas is supplied into the processing container 1 at a relatively large flow rate, for example, a flow rate larger than the flow rate of the carrier gas. _{Therefore, the TiCl 4} gas remaining in the processing container 1 is quickly discharged to the exhaust pipe 41, and the inside of the processing container 1 is _{replaced with the N 2} gas atmosphere from the _{TiCl 4} gas atmosphere in a short time. Further, since the O ₂ gas is supplied into the processing container 1, a part of _{the TiCl 4} gas adsorbed on the wafer W is oxidized. On the other hand, the valve 51e is closed, TiCl ₄ gas supplied from TiCl ₄ supply source 51a to the gas supply line 51b is stored in the storage tank 51d, boosts the storage tank 51d is.

After a predetermined time (for example, 0.03 to 3.0 seconds) has elapsed from opening the

valves

53e, 57e, 55e, the

valves

53e, 57e, 55e are closed and the

valves

52e, 56e are opened. As a result, the supply of the purge gas and the O ₂ _{gas into the processing container 1 is stopped, the NH 3} gas stored in the

storage tanks

52d and 56d is supplied into the processing container 1, and the TiCl _{4 adsorbed on the wafer W is supplied.} The gas is nitrided (step S3). At this time, valve 53e, by 57e is closed, _{N 2} supply source 53a, gas supply line 53b from 57a, the purge gas are respectively supplied to 57b stored storage tank 53d, the 57d, the reservoir tank 53d, the 57d Boosts. Further, since the valve 55e is closed, _{O 2} gas from the _{O 2} supply source 55a is supplied to the gas supply line 55b is stored in the storage tank 55d, the storage tank 55d is boosted.

valves

52e and 56e, the

valves

52e and 56e are closed and the valves 53e and 57e are opened. _{As a result, the supply of NH 3} gas into the processing container 1 is stopped, and the purge gas stored in the

storage tanks

53d and 57d is supplied into the processing container 1 (step S4). At this time, since the gas is supplied from the

storage tanks

53d and 57d in the state where the pressure is increased, the purge gas is supplied into the processing container 1 at a relatively large flow rate, for example, a flow rate larger than the flow rate of the carrier gas. _{Therefore, the NH 3} gas remaining in the processing container 1 is quickly discharged to the exhaust pipe 41, and the inside of the processing container 1 is _{replaced with the N 2} gas atmosphere from the _{NH 3} gas atmosphere in a short time. On the other hand, the valve 52e, by 56e is closed, NH ₃ gas supplied NH ₃ supply source 52a, from 56a the gas supply line 52 b, and 56b are stored storage tank 52 d, the 56d, the reservoir tank 52 d, the 56d Boosts.

By carrying out one cycle of the above steps S1 to S4, a TiON unit film in which oxygen (O) is added to TiN is formed on the wafer W. Then, by repeating the cycle of steps S1 to S4 a predetermined number of times X (step S5), a TiON film having a predetermined film thickness is formed on the wafer W.

After that, the wafer W is carried out from the processing container 1 in the reverse procedure of the loading into the processing container 1.

In the above example, in step S2 and step S4, the storage tank 53d, it has been described a case in which purge supply to the processing chamber 1 into the processing chamber 1 the reservoir purge gas (N ₂ gas) to 57d , Not limited to this. For example, storage tank 53d, without supplying stored purge gas _{(N 2} gas) into the processing chamber 1 to 57d, _{N 2} supply source 54a, a carrier gas supplied into the processing container 1 from 58a _{(N 2} gas ) May be purged in the processing container 1.

With reference to FIGS. 2 and 4, another example of a method of forming a TiON film on the wafer W using the above-mentioned film forming apparatus will be described. Figure 4 is a diagram showing another example of a gas supply sequence of the film-forming method of the embodiment, by supplying O ₂ gas into the processing vessel 1 at step S4, O ₂ gas into the processing chamber 1 in step S2 The gas supply sequence when is not supplied is shown.

In the example shown in FIG. 4, in step S2, after a predetermined time has elapsed from opening the valve 51e, the valve 51e is closed and the valves 53e and 57e are opened. _{As a result, the supply of TiCl 4} gas into the processing container 1 is stopped, and the purge gas stored in the

storage tanks

53d and 57d is supplied into the processing container 1.

Further, in step S4, after a predetermined time has elapsed from opening the

valves

52e and 56e, the

valves

52e and 56e are closed and the

valves

53e, 57e and 55e are opened. _{As a result, the supply of NH 3} gas into the processing container 1 is stopped, and the purge gas stored in the

storage tanks

53d and 57d and the O ₂ gas stored in the storage tank 55d are supplied into the processing container 1. Note that steps S1 and S3 may be the same as the example shown in FIG.

In the example shown in FIG. 4, similarly to the example shown in FIG. 3, the TiON unit in which oxygen (O) is added to TiN on the wafer W by carrying out one cycle of steps S1 to S4. Form a film. Then, by repeating the cycle of steps S1 to S4 a predetermined number of times X (step S5), a TiON film having a predetermined film thickness is formed on the wafer W.

Further, another example of the method of forming a TiON film on the wafer W by using the above-mentioned film forming apparatus will be described with reference to FIGS. 2 and 5. FIG. 5 is a diagram showing still another example of the gas supply sequence of the film forming method of the embodiment, and shows the gas supply sequence when _{O 2 gas is supplied into the processing container 1 in steps S2 and S4.}

In the example shown in FIG. 5, in step S2, after a predetermined time has elapsed from opening the valve 51e, the valve 51e is closed and the

valves

storage tanks

53d and 57d and the O ₂ gas stored in the storage tank 55d are supplied into the processing container 1.

Further, in step S4, after a predetermined time has elapsed from opening the

valves

52e and 56e, the

valves

52e and 56e are closed and the

valves

storage tanks

In the example shown in FIG. 5, similarly to the example shown in FIG. 3, the TiON unit in which oxygen (O) is added to TiN on the wafer W by carrying out one cycle of steps S1 to S4. Form a film. Then, by repeating the cycle of steps S1 to S4 a predetermined number of times X (step S5), a TiON film having a predetermined film thickness is formed on the wafer W.

With reference to FIGS. 2 and 6, still another example of a method of forming a TiON film on the wafer W using the above-mentioned film forming apparatus will be described. FIG. 6 is a diagram showing still another example of the gas supply sequence of the film forming method of the embodiment, and shows a gas supply sequence when _{O 2 gas is supplied into the processing container 1 during a part of the period of step S2.} show.

In the example shown in FIG. 6, in step S2, after a predetermined time has elapsed from opening the valve 51e, the valve 51e is closed and the valves 53e and 57e are opened. _{As a result, the supply of TiCl 4} gas into the processing container 1 is stopped, and the purge gas stored in the

storage tanks

53d and 57d is supplied into the processing container 1. Further, after a predetermined time has elapsed from opening the valves 53e and 57e, the valves 55e are opened. _{As a result, the O 2} gas stored in the storage tank 55d is supplied into the processing container 1 from the middle of the period of step S2. Further, in step S2, the valves 53e and 57e are closed after a predetermined time has elapsed since the valve 55e was closed.

Further, in step S4, after a predetermined time has elapsed from opening the

valves

52e and 56e, the

valves

storage tanks

53d and 57d is supplied into the processing container 1. Note that steps S1 and S3 may be the same as the example shown in FIG.

In the example shown in FIG. 6, similarly to the example shown in FIG. 3, the TiON unit in which oxygen (O) is added to TiN on the wafer W by carrying out one cycle of steps S1 to S4. Form a film. Then, by repeating the cycle of steps S1 to S4 a predetermined number of times X (step S5), a TiON film having a predetermined film thickness is formed on the wafer W.

Although the method of forming the TiON film on the wafer W by using the film forming apparatus has been described above with reference to FIGS. 2 to 6, the present disclosure is not limited to this. For example, in the example shown in FIG. 4, O ₂ gas may be supplied into the processing container 1 during a part of the period of step S4. _{Further, in the example shown in FIG. 5, the O 2} gas may be supplied into the processing container 1 during at least a part of the period of step S2 and step S4.

〔evaluation〕
(Film formation speed and in-plane uniformity)
With reference to FIG. 7, the film forming speed and in-plane uniformity of the TiON film formed by the film forming method of the embodiment using the above-mentioned film forming apparatus will be described. FIG. 7 is a diagram showing the relationship between the number of cycles and the film thickness. In FIG. 7, the horizontal axis indicates the number of cycles [times], and the vertical axis indicates the film thickness [Å].

The plot indicated by the black circle (●) in FIG. 7 shows the result when a TiON film is formed on the substrate by the film forming method shown in FIG. 3 described above (hereinafter referred to as “Example 1”). .. That is, the results when the _{O 2} gas is supplied in the step S2 for purging the _{TiCl 4} _{gas and the O 2} gas is not supplied in the step S4 for purging the _{NH 3 gas are shown.}

The plot indicated by the white circle (◯) in FIG. 7 shows the result when a TiON film is formed on the substrate by the film forming method shown in FIG. 4 described above (hereinafter referred to as “Example 2”). .. That is, the results when the _{O 2} gas is supplied in the step S4 for purging the _{NH 3} _{gas and the O 2} gas is not supplied in the step S2 for purging the _{TiCl 4 gas are shown.}

In the plot indicated by the square (■) in FIG. 7, TiCl ₄ supply, purge, NH ₃ supply, and purge are set as one cycle, and this cycle is repeated without supplying _{O 2 gas at the time of purging.} The result of the case where the TiN film is formed on the film (hereinafter referred to as "Comparative Example 1") is shown.

The plot indicated by the diamond (◆) in FIG. 7 has a TiCl ₄ supply, a purge, an NH ₃ supply, a purge, an O ₂ supply, and a purge as one cycle, and this cycle is repeated to form a TiON film on the substrate. The result of this case (hereinafter referred to as "Comparative Example 2") is shown.

In any of the above film forming methods, the film was formed by setting the substrate temperature to 300 ° C.

As shown in FIG. 7, it can be seen that the film thickness of the TiON film (TiN film) is proportional to the number of cycles in any of the film forming methods. That is, it can be said that even if the supply of O ₂ gas in the step S4 of purging steps S2 and NH ₃ gas to purge the TiCl ₄ gas, the same film thickness controllability and if not supplying O ₂ gas is obtained.

Further, in Example 1, Example 2, and Comparative Example 2, the film thicknesses of the TiON films at a plurality of locations in the plane of the substrate were measured, and 1σ% (standard deviation σ was divided by the average value) based on the measured film thickness. The value displayed as a percentage) was calculated. As a result, the values of 1σ% in Example 1, Example 2, and Comparative Example 2 were 1.09, 1.37, and 1.07, respectively. According to this result, even if the _{O 2} gas is supplied in the step S2 for purging the _{TiCl 4} gas and the step S4 for purging the _{NH 3} gas, the step of supplying the _{O 2} gas is performed separately from the step of purging. It can be said that the same in-plane uniformity can be obtained.

(particle)
First, a TiON film was formed on a bare silicon wafer, which is an example of a substrate, by the film forming methods shown in FIGS. 3 and 4 using the above-mentioned film forming apparatus. Subsequently, the number of particles having a particle size of 0.032 μm or more adhering to the surface of the TiON film was measured, and it was confirmed whether the number of particles was equal to or less than the reference value (10 particles). In the particle evaluation, the film forming methods shown in FIGS. 3 and 4 were performed 5 times each, and the number of particles was measured for each.

In the film forming method shown in FIG. 3, the number of particles was 0, 4, 0, 1, and 9, which were below the reference value for all five times. That is, _{even if the O 2} gas was added in step S2 for purging the _{TiCl 4} gas, no adverse effect on the particle performance was confirmed.

In the film forming method shown in FIG. 4, the number of particles was 0, 2, 1, 0, and 5, which were below the reference value for all five times. That is, _{even if the O 2} gas was added in step S4 for purging the _{NH 3} gas, no adverse effect on the particle performance was confirmed.

The conditions of the film forming method shown in FIGS. 3 and 4 in the evaluation of particles are as follows.

(Conditions of the film forming method shown in FIG. 3)
Substrate temperature: 300 ° C
TiCl ₄ (flow control controller 51c): 140 sccm
NH ₃ (Flow controller 52c): 7000 sccm
N ₂ (flow controller 53c): 3600 sccm
N ₂ (flow rate controller 54c): 4500 sccm
N ₂ (flow rate controller 57c): 3600 sccm
N ₂ (flow rate controller 58c): 4500 sccm
O ₂ (Flow controller 55c): 1130sccm
Time: S1 / S2 / S3 / S4 = 0.05 / 0.2 (O ₂ gas addition) /0.3/0.3 seconds O ₂ gas storage time in the storage tank 55d: 0.75 seconds O ₂ Gas supply time: 0.1 seconds Number of cycles: 96 times

(Conditions of the film forming method shown in FIG. 4)
Substrate temperature: 300 ° C
TiCl ₄ (flow control controller 51c): 140 sccm
NH ₃ (Flow controller 52c): 7000 sccm
N ₂ (flow controller 53c): 3600 sccm
N ₂ (flow rate controller 54c): 4500 sccm
N ₂ (flow rate controller 57c): 3600 sccm
N ₂ (flow rate controller 58c): 4500 sccm
O ₂ (Flow controller 55c): 1130sccm
Time: S1 / S2 / S3 / S4 = 0.05 / 0.2 / 0.3 / 0.3 seconds _{(O 2} gas addition)
Storage time in storage tank 55d: 0.75 seconds O ₂ gas supply time: 0.1 seconds Number of cycles: 107 times

(Oxygen concentration in the membrane)
The evaluation result of the oxygen concentration in the TiON film formed by the film forming method of the embodiment using the above-mentioned film forming apparatus will be described with reference to FIGS. 8 to 10.

FIG. 8 is a diagram showing the relationship between the oxygen supply time and the oxygen concentration in the membrane. In FIG. 8, the horizontal axis represents the oxygen supply time [seconds], and the vertical axis represents the oxygen concentration [%] in the membrane.

The plot indicated by the black circle (●) in FIG. 8 shows the result when a TiON film is formed on the substrate by the film forming method shown in FIG. 3 described above. That is, the results when the _{O 2} gas is supplied in the step S2 for purging the _{TiCl 4} _{gas and the O 2} gas is not supplied in the step S4 for purging the _{NH 3 gas are shown.}

The plot indicated by the white circle (◯) in FIG. 8 shows the result when a TiON film is formed on the substrate by the film forming method shown in FIG. 4 described above. That is, the results when the _{O 2} gas is supplied in the step S4 for purging the _{NH 3} _{gas and the O 2} gas is not supplied in the step S2 for purging the _{TiCl 4 gas are shown.}

As shown in FIG. 8, the _{O 2} gas is supplied in step S2 of purging TiCl ₄ gas, if not supplying _{O 2} gas in the step S4 of purging NH ₃ gas, lengthening the supply time of the _{O 2} gas It can be seen that the higher the oxygen concentration in the membrane, the higher the oxygen concentration in the membrane. That is, it can be said that the oxygen concentration in the membrane can be adjusted by changing the supply time _{of the O 2} gas in step S2 for purging the _{TiCl 4 gas.}

On the other hand, the _{O 2} gas is supplied in the step S4 of purging NH ₃ gas, if not supplying _{O 2} gas in step S2 of purging TiCl ₄ gas, film oxygen concentration by changing the supply time of the _{O 2} gas It turns out that is almost constant.

From these results, it is considered effective to supply _{O 2} _{gas and change the supply time of O 2} gas in step S2 of purging the _{TiCl 4} gas when adjusting the oxygen concentration in the membrane.

FIG. 9 is a diagram showing the relationship between the oxygen flow rate and the oxygen concentration in the membrane when the substrate temperature is constant. In FIG. 9, the horizontal axis shows the oxygen flow rate [sccm], and the vertical axis shows the oxygen concentration in the membrane [%].

The plot indicated by the black circle (●) in FIG. 9 shows the result when a TiON film is formed on the substrate by the film forming method shown in FIG. 3 described above. That is, the results when the _{O 2} gas is supplied in the step S2 for purging the _{TiCl 4} _{gas and the O 2} gas is not supplied in the step S4 for purging the _{NH 3 gas are shown.}

The plot indicated by the white circle (◯) in FIG. 9 shows the result when the TiON film is formed on the substrate by the film forming method shown in FIG. 4 described above. That is, the results when the _{O 2} gas is supplied in the step S4 for purging the _{NH 3} _{gas and the O 2} gas is not supplied in the step S2 for purging the _{TiCl 4 gas are shown.}

As shown in FIG. 9, the O ₂ gas is supplied in step S2 of purging TiCl ₄ gas, if not supplying O ₂ gas in the step S4 of purging NH ₃ gas, film oxygen higher the oxygen flow rate It can be seen that the concentration increases. That is, it can be said that the oxygen concentration in the membrane can be adjusted by changing the oxygen flow rate in step S2 for purging the _{TiCl 4 gas.}

On the other hand, the O ₂ gas is supplied in the step S4 of purging NH ₃ gas, a TiCl ₄ gas when not supplying O ₂ gas in step S2 of purging, film oxygen concentration by changing the oxygen flow rate at a substantially constant It turns out that there is.

_{From these results, it is considered effective to supply O 2} gas and change the oxygen flow rate in step S2 of purging the _{TiCl 4} gas when adjusting the oxygen concentration in the membrane.

FIG. 10 is a diagram showing the relationship between the oxygen flow rate and the oxygen concentration in the membrane when the substrate temperature is changed. In FIG. 10, the horizontal axis represents the oxygen flow rate [sccm], and the vertical axis represents the oxygen concentration [%] in the membrane.

For the plots indicated by the triangle (▲) mark, circle (●) mark, square (■) mark, and diamond (◆) mark in FIG. 10, the substrate temperature is set to 300 ° C., 350 ° C., 375 ° C., and 400 ° C., respectively. The result when the TiON film is formed on the substrate by the film forming method shown in FIG. 3 described above is shown.

As shown in FIG. 10, it can be seen that the oxygen concentration in the membrane increases as the oxygen flow rate in step S2 for purging the _{TiCl 4} gas increases at any temperature in the substrate temperature range of 300 ° C. to 400 ° C. That is, at any temperature in the range substrate temperature of 300 ° C. ~ 400 ° C., by changing the oxygen flow rate in the step S2 of purging the TiCl ₄ gas, it said to be adjusted the oxygen concentration in the film. Further, it can be said that a TiON film having a low oxygen concentration in the film (for example, 25 to 40%) can be formed by reducing the time and flow rate of supplying the oxygen gas in step S2 for purging the _{TiCl 4 gas.}

The conditions of the film forming method shown in FIG. 3 in the evaluation of the oxygen concentration in the film are as follows.

(Conditions of the film forming method shown in FIG. 3)
Substrate temperature: 300, 350, 375, 400 ° C
TiCl ₄ (flow control controller 51c): 140 sccm
NH ₃ (Flow controller 52c): 7000 sccm
N ₂ (flow controller 53c): 3600 sccm
N ₂ (flow rate controller 54c): 4500 sccm
N ₂ (flow rate controller 57c): 3600 sccm
N ₂ (flow rate controller 58c): 4500 sccm
O ₂ (Flow controller 55c): 15, 30, 50, 100, 300 sccm
Time: S1 / S2 / S3 / S4 = 0.05 / 0.2 (O ₂ gas addition) /0.3/0.3 seconds O ₂ gas storage time in the storage tank 55d: 0.82 seconds O ₂ Gas supply time: 0.03 seconds Number of cycles: 96 times

In the above embodiment, titanium (Ti) is an example of the first element, and TiCl ₄ gas is an example of the first reaction gas. Also, nitrogen (N) is an example of a second element, NH ₃ gas is an example of a second reaction gas. Oxygen (O) is an example of a third element, and O ₂ gas is an example of a third reaction gas.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The above-described embodiment may be omitted, replaced, or changed in various forms without departing from the scope and purpose of the appended claims.

In the above embodiment, the case of forming a TiON film as an example of the film forming method has been described as an example, but the present disclosure is not limited to this, and can be applied to the case of forming a film containing at least three elements. .. Another example of a film containing three elements is, for example, a TiSiN film. _{When forming the TiSiN film, a silicon-containing gas such as monosilane (SiH 4} ) gas or dichlorosilane (DCS) gas may be used instead of the oxygen-containing gas.

This international application claims priority based on Japanese Patent Application No. 2020-076194 filed on April 22, 2020, and the entire contents of the application will be incorporated into this international application.

1 Processing container

Claims

A method for forming a film containing at least three elements.
The step of supplying the first reaction gas containing the first element into the processing container, and
The step of purging the first reaction gas and
A step of supplying a second reaction gas containing a second element that reacts with the first reaction gas into the processing container,
The step of purging the second reaction gas and
Have,
In at least one of the step of purging the first reaction gas and the step of purging the second reaction gas, a third reaction gas containing a third element is supplied into the processing container.
Film formation method.
In the step of purging the first reaction gas, the third reaction gas is supplied into the processing container, and the third reaction gas is supplied.
In the step of purging the second reaction gas, the third reaction gas is not supplied into the processing container.
The film forming method according to claim 1.
It further comprises a step of supplying the first reaction gas, a step of purging the first reaction gas, a step of supplying the second reaction gas, and a step of repeating the step of purging the second reaction gas.
The film forming method according to claim 1 or 2.
In the step of purging the first reaction gas and the step of purging the second reaction gas, the inert gas is supplied into the processing container.
The film forming method according to any one of claims 1 to 3.
The first reaction gas is a gas containing a metal, and is a gas containing a metal.
The second reaction gas is a nitrogen-containing gas, and the second reaction gas is a nitrogen-containing gas.
The third reaction gas is an oxygen-containing gas or a silicon-containing gas.
The film forming method according to any one of claims 1 to 4.
The first reaction gas is TiCl 4 gas, and the first reaction gas is TiCl 4 gas.
The second reaction gas is NH 3 gas,
The third reaction gas is O 2 gas.
The film forming method according to any one of claims 1 to 5.