Film formation method and film formation device

Abstract

To enhance the coverage of a film with respect to the surface of a substrate during film formation on the substrate.SOLUTION: This film formation method includes: a film formation step of alternately and repeatedly supplying a starting material gas and a reaction gas into a process chamber, and forms a film of a reaction product on a substrate in the process chamber; a purge step of, in each purge period between a first period when one of the starting material gas and the reaction gas is supplied into the process chamber and a second period when the other is supplied into the process chamber, supplying a purge gas and purges an atmosphere in the process chamber; and an opening degree changing step of, for an opening degree of a valve provided in an exhaust path for exhausting the inside of the process chamber, the exhaust amount inside the process chamber being increased by increasing the opening degree, setting the opening degree at a first opening degree midway through one of the first period and the second period, and sets the opening degree at a second opening degree larger than the first opening degree from the midway to the next purge period.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present disclosure relates to a film forming method and a film forming apparatus.

Background Art

[0002] When manufacturing a semiconductor device, various films are formed on the surface of a semiconductor wafer (hereinafter referred to as a wafer) which is a substrate. This film formation may be performed by ALD (Atomic Layer Deposition).

[0003] Patent Document 1 describes that it is preferable to set the film forming rate per cycle so as to suppress CVD (Chemical Vapor Deposition) during the execution of ALD. Patent Document 2 shows that when forming a film on a substrate in a chamber by ALD, CVD caused by applying RF radiation to a gas of a film precursor that is non-adsorbed on the substrate in the chamber immediately before the end of the film forming process can also be utilized.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a technique capable of improving the coverage of a film with respect to the surface of a substrate when forming a film on the substrate.

Means for Solving the Problems

[0006] The film formation method of the present disclosure alternately and repeatedly supplies a source gas as a film formation raw material and a reaction gas that reacts with the source gas to generate a reaction product into a processing container, and forms a film of the reaction product on a substrate in the processing container, In each purge period between a first period in which one of the source gas and the reaction gas is supplied into the processing container and a second period in which the other of the source gas and the reaction gas is then supplied into the processing container, a purge gas is supplied into the processing container to purge the atmosphere in the processing container, Regarding the opening degree of a valve provided in an exhaust passage for exhausting the inside of the processing container, and increasing the exhaust amount in the processing container by increasing the opening degree, the opening degree is set to a first opening degree until halfway through one of the first period and the second period, and is set to a second opening degree larger than the first opening degree from halfway through to the next purge period, including.

Effects of the Invention

[0007] The present disclosure can improve the film covering property of the film with respect to the surface of the substrate when forming a film on the substrate.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Mode for Carrying Out the Invention

[0009] An example of the film forming method of the present disclosure will be described. In this example, various gases are supplied into a processing container storing a wafer W. TiCl 4 (titanium tetrachloride) gas supply (step S1), purge gas supply for purging the atmosphere in the processing container (step S2), NH 3 (ammonia) gas supply (step S3), and the above purge gas supply (step S4) are performed in this order as one cycle. Then, this cycle is repeated, and TiCl, which is a source gas serving as a film forming raw material, 4 gas and NH, which is a reaction gas, 3 TiN (titanium nitride), which is a reaction product of the gas, is deposited on the surface of the wafer W to form a film. That is, a TiN film is formed in the ALD mode.

[0010] In addition to the examples, for the sake of easy understanding, a comparative example of forming a TiN film by repeating steps S1 to S4 in the same manner as in the examples will also be described based on the reaction mechanism estimated from the results of the evaluation tests described later. In the description of each example, refer to the schematic diagrams of FIGS. 1 to 10, which schematically show the reactions on the surface of the wafer W. In FIGS. 1 to 10, the elements constituting each molecule are shown as circles, and different types of elements are distinguished from each other by attaching different patterns inside the circles.

[0011] First, referring to FIGS. 1 to 5, the comparative example will be described. As step S1, TiCl gas, which is the first film-forming gas, is supplied into the processing chamber, and TiCl molecules 11 are adsorbed on the surface of the wafer W (FIG. 1). This adsorption includes TiCl molecules 11 adsorbed on the surface of the wafer W by chemisorption with relatively strong adsorption force and TiCl molecules 11 adsorbed on the surface of the wafer W by physisorption with relatively weak adsorption force coexisting. Next, as step S2, purging of the inside of the processing chamber is performed by supplying a purge gas. By this purging, the desorption of the physisorbed TiCl molecules 11 from the surface of the wafer W proceeds, and by continuing the purging for a relatively long time, the chemisorbed TiCl molecules 11 remain on the surface of the wafer W (FIG. 2). 4 gas is supplied into the processing container, and TiCl 4 molecules 11 are adsorbed on the surface of the wafer W. This adsorption is such that TiCl 4 molecules 11 adsorbed on the surface of the wafer W by chemisorption with relatively strong adsorption force and TiCl 4 molecules 11 adsorbed on the surface of the wafer W by physisorption with relatively weak adsorption force coexist. Next, as step S2, purging of the inside of the processing container is performed by supplying a purge gas. By this purging, the desorption of the physisorbed TiCl 4 molecules 11 from the surface of the wafer W proceeds, and by continuing the purging for a relatively long time, the chemisorbed TiCl 4 molecules 11 remain on the surface of the wafer W (FIG. 2).

[0012] Then, as step S3, NH gas, which is the second film-forming gas, is supplied to the wafer W, and NH 3 molecules 12 are adsorbed on the surface of the wafer W (FIG. 3). Regarding the adsorption of this NH 3 molecules 12, similar to the adsorption of TiCl 3 molecules 11, chemisorption and physisorption coexist. Subsequently, as step S4, purging of the inside of the processing chamber is performed by supplying a purge gas. By this purging, the desorption of the physisorbed NH 4 molecules 12 from the surface of the wafer W proceeds, and by continuing the purging for a relatively long time, the chemisorbed NH 3 molecules 12 remain on the surface of the wafer W. The TiCl 3 molecules 12 remaining adsorbed on the wafer W. The TiCl remaining adsorbed on the wafer W 4Molecule 11 and NH 3 Molecule 12 reacts to produce TiN molecule 13 (Figure 4). NH 4 Cl molecules, shown as 14 in the figure, desorb from the wafer W as by-products of this reaction.

[0013] As described above, in one cycle, the TiCl physically adsorbed on the surface of the wafer W 4 molecule 11 and NH 3 molecule 12 desorb by purging respectively, and the TiCl remaining on the surface of the wafer W 4 molecule 11, NH 3 molecule 12 becomes sparse. Therefore, in this one cycle, these TiCl 4 molecule 11 and NH 3 molecule 12 also become sparse as the TiN molecule 13, which is a reaction product generated therefrom. Therefore, for the TiN film 10 formed on the surface of the wafer W by repeating this cycle, there is a possibility of becoming discontinuous in the plane of the wafer W as shown in Figure 5. Therefore, there is a possibility that the covering property of the TiN film 10 with respect to the surface of the wafer W cannot be made sufficiently high.

[0014] Subsequently, referring to FIGS. 6 to 10, examples will be described. As step S1, TiCl 4 gas is supplied into the processing vessel, and TiCl 4 molecule 11 adsorbs on the surface of the wafer W (Figure 6). Next, as step S2, purging inside the processing vessel is performed by supplying a purge gas (Figure 7). This purge ends in a short time, and as step S3, NH 3 gas is supplied to the wafer W, and NH 3 molecule 12 adsorbs on the surface of the wafer W (Figure 8). That is, in addition to the chemisorbed molecule 11, NH 4 molecule 12 is adsorbed on the surface of the wafer W with a large number of TiCl 3 molecule 11 remaining on the surface of the wafer W.

[0015] Then, as step S4, purging inside the processing container is performed by supplying purge gas (FIG. 9). This purging also ends in a short time. Therefore, when step S1 of the next cycle is performed, in addition to the chemically adsorbed NH 3 molecules 12, a large number of physically adsorbed NH 3 molecules 12 remain on the surface of the wafer W, and TiCl 4 molecules 11 are supplied to and adsorbed on the surface of the wafer W, and TiN molecules 13 are generated by the reaction between them.

[0016] Hereinafter, in some cases, the execution times of steps S2 and S4 for purging inside the processing container 21 are described as purge times. As described above, in the embodiment, the purge time is set relatively short. Thereby, physical adsorption of one of TiCl 4 molecules 11 and NH 3 molecules 12 is maintained, so that a large number of the one molecules remain on the surface of the wafer W, and the other of TiCl 4 molecules 11 and NH 3 molecules 12 is newly supplied to the wafer W and adsorbed on the surface of the wafer W. By adsorbing each molecule in this way and reacting with each other, TiN molecules 13 are formed on the surface of the wafer W with high uniformity and density in one cycle.

[0017] Therefore, for the TiN film 10 formed on the surface of the wafer W by depositing TiN molecules 13 by repeating this cycle, as shown in FIG. 10, the formation of discontinuous portions can be suppressed, so that the coverage of the surface of the wafer W can be increased. Further, in this embodiment, since the purge time is short, there is an advantage that the time required for the film formation process is shortened.

[0018] However, shortening the purge time means that TiCl 4 gas and NH 3When one of the gases is not sufficiently removed and the other gas is supplied, the likelihood of a reaction between these gases in the gas phase within the processing vessel increases. If a reaction occurs in this gas phase, the reaction product deposits on the wafer W to form the TiN film 10. That is, during film formation by ALD, film formation by CVD also occurs. Generally, the film formed on the wafer W by CVD has lower covering properties compared to the film formed on the wafer W by ALD. That is, if the reaction between the gases in the gas phase described above occurs, there is a concern that the covering property of the TiN film 10 with respect to the surface of the wafer W cannot be made sufficiently high.

[0019] The film forming apparatus 2 shown in FIG. 11 is an apparatus for performing the above-described embodiment, and operation control is performed so that film formation by CVD can be suppressed even when the purge time described above is set relatively short. Therefore, the TiN film 10 can be formed so that the covering property with respect to the surface of the wafer W is high.

[0020] Describing the outline of the configuration and processing of the film forming apparatus 2, a valve V is provided in an exhaust passage 28 connecting the processing vessel 21 of the film forming apparatus 2 and the exhaust mechanism 29. The valve V is a valve called an APC (Auto Pressure Control) valve, and for the inside of the processing vessel 21, more specifically, for the processing space 40 formed around the wafer W inside the processing vessel 21, its opening degree is changed during the processing of the wafer W so that the pressure is within a desired range. The larger the opening degree of the valve V, the larger the exhaust amount per unit time of the processing space 40 by the action of the exhaust mechanism 29, and the lower the pressure of the processing space 40.

[0021] At the beginning of the start of step S1, TiCl 4 By increasing the residence of the gas in the processing space 40, the adsorption property of the molecules 11 of TiCl 4 to the wafer W is increased, and the opening degree of the valve V is set to a relatively small first opening degree. Then, during the execution of this step S1, the opening degree of the valve V is changed to a relatively large second opening degree, and the supply of the purge gas in step S2 is executed at the second opening degree. Similarly, at the beginning of the start of step S3, NH3 By increasing the retention in the gas treatment space 40, the adsorption of the NH 3 molecules 12 to the wafer W is increased by setting the opening degree of the valve V to a relatively small first opening degree. During the execution of this step S3, the opening degree of the valve V is set to a relatively large second opening degree, and the supply of the purge gas in step S4 is executed at the second opening degree. That is, the pressure in the treatment space 40 is reduced before the start of steps S2 and S4 so that the purge gas supplied to the treatment space 40 is quickly exhausted from the treatment space 40.

[0022] Furthermore, in steps S1 and S3, the purge gas is stored in the tanks 54B and 54F provided in the flow path connected to the processing container 21 so that the inside of the tanks 54B and 54F becomes a relatively high pressure, and in steps S2 and S4, the purge gas is supplied from the inside of the tanks 54B and 54F to the processing space 40. Thereby, a large amount of purge gas is supplied to the processing space 40 in a short purge time.

[0023] By supplying and exhausting the purge gas to and from the processing container 21 as described above, the flowability of the purge gas in the processing space 40 is increased. Thereby, until one of the TiCl 4 gas and the NH 3 gas is supplied to the processing space 40 and then the other gas is supplied next, the one gas is prevented from remaining in the processing space 40, and the reaction of these gases in the gas phase is suppressed.

[0024] Hereinafter, the configuration of the film forming apparatus 2 will be described more specifically. The film forming apparatus 2 includes a processing container 21, a mounting table 31, a shower head 4, and a gas supply mechanism 5. The processing container 21 is composed of a circular container body 22, an exhaust duct 23, and a ceiling wall 24 in a plan view. A transfer port 26 for the wafer W that can be opened and closed by a gate valve 25 is formed on the side wall of the container body 22. The exhaust duct 23 is configured in an annular shape with a rectangular longitudinal section, and is provided along the periphery of the container body 22 on the container body 22, and forms the side wall of the processing container 21.

[0025] A slit-shaped exhaust port 27 is open along the inner peripheral surface of the exhaust duct 23. One end of an exhaust passage 28, in which the valve V is provided as described above, is connected to the outer peripheral surface of the exhaust duct 23, and the one end communicates with the exhaust port 27. An exhaust mechanism 29 to which the other end of the exhaust passage 28 is connected is constituted by, for example, a vacuum pump, and by exhausting the inside of the processing container 21 through the exhaust port 27, the inside of the processing container 21 is made into a vacuum atmosphere. A ceiling wall 24 is provided above the exhaust duct 23.

[0026] A mounting table 31 is provided in the processing container 21, and the wafer W is horizontally mounted thereon. A heater 32 is embedded in the mounting table 31, and the mounted wafer W is heated to a desired temperature. Reference numeral 33 in the drawing is a cover, which covers the mounting table 31 from the peripheral edge portion to the side surface of the upper surface of the mounting table 31. Reference numeral 30 in the drawing is a vertical through-hole provided in the mounting table 31, through which a pin 38 described later is inserted. The upper end of a support column 34 is connected to the bottom surface of the mounting table 31, and the lower end side of the support column 34 is connected to a lifting mechanism 35 provided outside the processing container 21 through an opening in the bottom wall of the processing container 21. By the lifting mechanism 35, the mounting table 31 moves up and down between the processing position shown by the solid line and the lowering position shown by the two-dot chain line below the processing position.

[0027] Outside the processing container 21, a flange 36 is provided on the support column 34, and a bellows 37 is connected between the flange 36 and the edge portion of the opening in the bottom wall of the processing container 21 to ensure the airtightness of the processing container 21. Near the bottom surface of the processing container 21, three (only two are shown in the drawing) vertical pins 38 are provided, and by moving up and down by a lifting mechanism 39 provided in the processing container 21, the wafer W is transferred between the mounting table 31 at the lowering position described above and a transfer mechanism (not shown).

[0028] Regarding the shower head 4, it includes a main body 41 with a concave shape in its longitudinal section that is upside down, and a shower plate 42 provided below the main body 41 so as to close the opening of the concave portion. The lower surface of the shower plate 42 faces the upper surface of the mounting table 31. A diffusion space 43 is formed inside the shower head 4 surrounded by the shower plate 42 and the main body 41, and a large number of gas discharge ports 44 provided in the shower plate 42 communicate with the diffusion space 43. In the figure, 45 and 46 are introduction holes for introducing gas into the diffusion space 43, which are formed through the ceiling wall 24 of the processing container 21 and the central portion of the main body 41.

[0029] The peripheral portion of the shower plate 42 (outside the formation region of the gas discharge ports 44) protrudes downward to form an annular protrusion 47, which is close to the cover 33 of the mounting table 31 at the processing position. The space formed between the mounting table 31 and the shower plate 42 at the processing position and surrounded by the annular protrusion 47 is the processing space 40, and the processing space 40 is exhausted through the annular gap formed between the annular protrusion 47 and the cover 33 by the exhaust from the exhaust port 27.

[0030] The height of the processing space 40 is shown as G. In order to sufficiently and surely distribute the purge gas in the processing space 40 for purging and shorten the purge time, it is preferable to make the height G small within the range where the gas flowability can be ensured. Specifically, the height G is, for example, 0.5 mm to 3.0 mm.

[0031] The gas supply mechanism 5 is composed of a gas flow path, a tank, a flow rate control unit, a valve, and various gas supply sources. The downstream end of the flow path 51A is connected to the introduction hole 45 described above, and the upstream side of the flow path 51A is connected to the TiCl gas supply source 53A via the flow rate control unit 52A in sequence. The downstream end of the flow path 51B is connected to the downstream side of the flow rate control unit 52A in the flow path 51A, and the upstream side of the flow path 51B is connected to the N gas supply source via the valve V1, the tank 54B, and the flow rate control unit 52B in sequence. 4 The downstream end of the flow path 51A is connected to the introduction hole 45 described above, and the upstream side of the flow path 51A is connected to the TiCl gas supply source 53A via the flow rate control unit 52A in sequence. The downstream end of the flow path 51B is connected to the downstream side of the flow rate control unit 52A in the flow path 51A, and the upstream side of the flow path 51B is connected to the N gas supply source via the valve V1, the tank 54B, and the flow rate control unit 52B in sequence. 2It is connected to the gas supply source 53B. The downstream end of the flow path 51C is connected to the upstream side of the tank 54B and the downstream side of the flow rate control unit 52B in the flow path 51B, and the upstream side of the flow path 51C is H via the flow rate control unit 52C 2 (Hydrogen) gas supply source 53C. The downstream end of the flow path 51D is connected to the downstream side of the valve V1 in the flow path 51B, and the upstream side of the flow path 51D is N via the flow rate control unit 52D 2 It is connected to the gas supply source 53D.

[0032] The downstream end of the flow path 51E is connected to the introduction hole 46 described above, and the upstream side of the flow path 51E is NH via the flow rate control unit 52E in sequence 3 It is connected to the gas supply source 53E. The downstream end of the flow path 51F is connected to the downstream side of the flow rate control unit 52E in the flow path 51E, and the upstream side of the flow path 51F is N via the valve V2, the tank 54F, and the flow rate control unit 52F in sequence 2 It is connected to the gas supply source 53F. The downstream end of the flow path 51G is connected to the upstream side of the tank 54F and the downstream side of the flow rate control unit 52F in the flow path 51F, and the upstream side of the flow path 51G is H via the flow rate control unit 52G 2 (Hydrogen) gas supply source 53G. The downstream end of the flow path 51H is connected to the downstream side of the valve V2 in the flow path 51F, and the upstream side of the flow path 51H is N via the flow rate control unit 52H 2 It is connected to the gas supply source 53H.

[0033] Each of the gas supply sources 53A to 53H includes a gas storage unit and a valve (not shown), and the supply and cut-off of the gas to the downstream sides of the flow paths 51A to 51H are performed by opening and closing the valve. The flow rate adjustment unit is constituted by, for example, a mass flow controller, and adjusts the flow rate of the gas supplied to the downstream side of the flow path.

[0034] N 2 The N gas supplied from the gas supply sources 53B and 53F 2 The gas is a purge gas. H 2 The H gas supplied from the gas supply sources 53C and 53G 2 The gas is, N 2 The N gas from the gas supply sources 53B and 53F 2It constitutes a purge gas together with the gas, reacts with chlorine contained in the TiN film 10 to remove the chlorine, and acts as a reforming gas for improving the film quality. N 2 From the gas supply sources 53D and 53H, in order to prevent the gas from flowing back from the processing space 40 to the gas supply mechanism 5, N is constantly supplied into the processing container 21 during the processing of the wafer W. 2 The gas is supplied. In this way, N 2 The N from the gas supply sources 53D and 53H 2 Since the gas is constantly supplied, when the film-forming gases (TiCl 4 gas and NH 3 gas) are not supplied into the processing container 21, it also serves as a purge gas. In this film-forming apparatus 2, a gas supply source is provided for each flow path, but the gas supply sources that supply the same type of gas may be shared.

[0035] The purge gas supply mechanism is constituted by the gas supply sources 53B to 53D, 53F to 53H, the flow rate control units 52B to 52D, 52F to 52H, the tanks 54B, 54F and the valves V1, V2. Among them, the valves V1, V2 are gas supply valves. Further, the film-forming gas supply mechanism is constituted by the gas supply sources 53A, 53E, the flow rate control units 52A, 52E.

[0036] The film-forming apparatus 2 includes a control unit 20 constituted by a computer. The program included in the control unit 20 incorporates a group of steps so as to be able to perform a series of operations described later in the film-forming apparatus 2. By the program, the control unit 20 outputs a control signal to each part of the film-forming apparatus 2, and the operations of each part are controlled. Specifically, operations such as the opening degree adjustment of the valve V, the opening and closing of the valves V1, V2, the supply and cut-off of each gas to the processing container 21 by the operation of each gas supply source, the temperature adjustment of the wafer W by the heater 32, and the raising and lowering of the mounting table 31 and the pins 38 by the elevating mechanisms 35, 39 are controlled by the control signal. The above program is stored in a storage medium such as a compact disk, a hard disk, a DVD, a memory card, etc., and installed in the control unit 20.

[0037] Next, the operation sequence of the film forming apparatus 2 for performing the processes of the embodiments described with reference to FIGS. 5 to 10 will be described with reference to the time chart of FIG. 12. The time chart shows the change over time in the opening degree of the valve V, and the supply timings of TiCl 4 gas, NH 3 gas, purge gas (N 2 gas and H 2 gas). Since the operation of the apparatus is controlled by the control signal from the control unit 20 as described above, it can be said that the time chart shows the output timings of the control signals for controlling the respective operations from the control unit 20.

[0038] Note that, as described above, N 2 gas is constantly supplied from the N 2 gas supply sources 53D and 53H into the processing container 21 during the processing of the wafer W. Therefore, this N 2 gas also acts as a purge gas. However, in the timing chart of this embodiment and the timing chart of the comparative example described later, only the N 2 gas and H 2 gas supplied through the tanks 54B and 54F are represented as purge gases, and their supply and cut-off are shown. Even in the following description along the timing chart, the description of stopping the supply of the purge gas refers to stopping the supply of the purge gas from the tanks 54B and 54F.

[0039] First, the wafer W is transported into the processing container 21, placed on the mounting table 31, and the gate valve 25 is closed. The wafer W is heated by the heater 32 to a predetermined temperature, and at the same time, the mounting table 31 rises to the processing position, and the processing space 40 is formed so that the aforementioned height G becomes the aforementioned size. N 2 gas is supplied from the N 2 gas supply sources 53D and 53H to the processing container 21, respectively, while the valve V is set to a predetermined opening degree A1, and the inside of the processing container 21 is adjusted to a predetermined vacuum pressure.

[0040] TiCl 4Gas is supplied to the processing space 40 (at time t1 in the chart), and step S1 described in FIG. 6 is started. On the other hand, with valves V1 and V2 closed, N which is a purge gas 2 gas and H 2 gas are supplied to tanks 54B and 54F, stored in the tanks 54B and 54F, and the pressure in the tanks 54B and 54F is increased so as to be higher than the pressure in the processing space 40.

[0041] TiCl 4 During the supply of TiCl gas to the processing space 40, the opening degree of valve V is changed to an opening degree A2 larger than the opening degree A1 (at time t2), and the exhaust volume increases, so that the pressure in the processing space 40 increased by the supply of TiCl gas decreases. 4 After that, the supply of TiCl gas to the processing space 40 is stopped and valves V1 and V2 are opened (at time t3), and step S2 described in FIG. 7 is started. That is, a large amount of purge gas is supplied to the processing space 40. Then, due to the fact that the processing space 40 is previously set to a low pressure, the purge gas is quickly removed from the processing space 40. By this flow of the purge gas, TiCl gas not adsorbed on the wafer W is removed from the processing space 40. 4 4

[0042] Then, when valves V1 and V2 are closed, the supply of purge gas to the processing space 40 is stopped, and NH gas is supplied to the processing space 40, and step S3 described in FIG. 8 is started. Also, simultaneously with the switching of the gas supplied to the processing space 40, the opening degree of valve V is changed to an opening degree A3 smaller than the opening degree A2 (at time t4). This change in the opening degree and the supply of NH gas cause the pressure in the processing space 40 to increase. 3 3

[0043] ​​​​As described above as a summary, the implementation time T2 of step S2 (the time from time t3 to time t4, which is the previously described purge time) is short, specifically, for example, shorter than the implementation time T1 of step S1 (the time from time t1 to time t3). Therefore, when step S3 is started, in addition to the chemically adsorbed TiCl 4 molecule 11 on the surface of the wafer W, there are a large number of physically adsorbed TiCl 4 molecules 11. Thus, when NH 3 gas is supplied in this step S3, TiN molecules 13 are generated with high uniformity over the entire surface of the wafer W.

[0044] While the reaction proceeds on the surface of the wafer W in this way, N 2 gas and H 2 gas, which are purge gases, are supplied to tanks 54B and 54F, stored in the tanks 54B and 54F, and the pressure inside the tanks 54B and 54F is increased to be higher than the pressure in the processing space 40.

[0045] Then, during the supply of NH 3 gas to the processing space 40, the opening degree of valve V is changed to an opening degree A2 larger than the opening degree A3 (time t5). As the exhaust volume increases, the pressure in the processing space 40 that has risen due to the supply of NH 3 gas decreases. After that, the supply of NH 3 gas to the processing space 40 is stopped and valves V1 and V2 are opened (time t6), and step S4 described in FIG. 9 is started, and a large amount of purge gas is supplied to the processing space 40. And because the processing space 40 is previously set to a low pressure, the purge gas is quickly removed from the processing space 40. Due to the flow of this purge gas, NH 3 gas that is not adsorbed on the wafer W is removed from the processing space 40.

[0046] Then, when valves V1 and V2 are closed, the supply of purge gas to the processing space 40 stops, and the tanks 54B and 54F start storing the purge gas again, and TiCl 4Gas is supplied. Simultaneously with the switching of the gas to this processing space 40, the opening degree of valve V is changed to an opening degree A1 smaller than the opening degree A2 (time t7), and the pressure in the processing space 40 rises. Accordingly, step S1 is started again.

[0047] As described above in summary, the execution time T4 of step S4 (the time from time t6 to time t7, which is the purge time described above) is short, specifically, for example, shorter than the execution time T3 of step S3 (the time from time t4 to time t6). Therefore, when step S1 is restarted, in addition to the NH molecules 12 chemisorbed on the surface of the wafer W, there are a large number of physisorbed NH molecules 12. Thus, when TiCl gas is supplied in this step S1, TiN molecules 13 are further generated with high uniformity over the entire surface of the wafer W. 3 In addition to the chemisorbed NH molecules 12 on the surface of the wafer W, there are a large number of physisorbed NH molecules 12. 3 molecules 12. Thus, when TiCl gas is supplied in this step S1, TiN molecules 13 are further generated with high uniformity over the entire surface of the wafer W. 4 gas is supplied, TiN molecules 13 are further generated with high uniformity over the entire surface of the wafer W.

[0048] Thereafter, steps S2 to S4 also proceed in the same manner as the first steps S2 to S4. When the formation of the TiN film 10 is completed as shown in FIG. 10 by repeating steps S1 to S4 a predetermined number of times, the wafer W is carried out of the processing container 21 in a procedure reverse to the carrying-in procedure into the processing container 21.

[0049] In the processing according to the embodiment using the film forming apparatus 2 as described above, the TiN film 10 can be formed so as to have high covering properties with respect to the surface of the wafer W. Further, since the purge time is short, the throughput of the film forming apparatus can be increased.

[0050] In the above processing, the time t2 for changing the opening degree of the valve V during the period from the time t1 when step S1 is performed to the time t3 corresponds to the first point in time, and the time t5 for changing the opening degree of the valve V during the period from the time t4 when step S3 is performed to the time t6 corresponds to the second point in time. And in step S1, a sufficient amount of TiCl 4In order to ensure that the gas is adsorbed onto the wafer W, the time from time t1 to time t2 is set to be longer than the time from time t2 to time t3. Similarly, in step S3, a sufficient amount of NH 3 In order to ensure that the gas is adsorbed onto the wafer W, the time from time t4 to time t5 is set to be longer than the time from time t5 to time t6.

[0051] Note that the opening degree A1 of the valve V during the time from time t1 to time t2 and the opening degree A3 of the valve V during the time from time t4 to time t5 are the first opening degrees described above, and the opening degree A2 of the valve V during the time from time t2 to time t4 and the time from time t5 to time t7 is the second opening degree described above. In order to keep the pressure in the processing space 40 within a predetermined range, the opening degree of the valve V is made different between the time t1 - t2 and the time t2 - t4 in this way. However, the relationship between the opening degree of the valve V during the time t1 - t2 and the opening degree of the valve V during the time t2 - t4 is not limited to this, and may be changed as appropriate. For example, the opening degree of the valve V during the time t1 - t2 and the opening degree of the valve V during the time t2 - t4 may be the same. The opening degree of the valve V during the time t2 - t4 and the opening degree of the valve V during the time t5 - t7 are not limited to being the same, and may be different.

[0052] A comparison is made between the TiN film formed by the film forming process of the example and the TiN film formed by the film forming process of the comparative example in the evaluation test described later. Therefore, the difference between the operation sequence of the film forming apparatus 2 in the film forming process of the comparative example and that during the film forming process of the example will be mainly described with reference to the time chart of FIG. 13.

[0053] TiCl 4 The gas is supplied to the processing space 40 (at time t11 in the chart), and step S1 described in FIG. 1 is started. On the other hand, the purge gas is stored in the tanks 54B and 54F. Thereafter, TiCl 4When the supply to the gas treatment space 40 stops (at time t12), step S2 described in FIG. 2 starts. Shortly after time t12, valves V1 and V2 open and purge gas is supplied to the treatment space 40, and the opening degree of valve V increases to become the opening degree A2 (at time t13). The pressure in the treatment space 40 decreases, and purging in the treatment space 40 proceeds.

[0054] Then the opening degree of valve V decreases to become the opening degree A3 (at time t14), and subsequently, valves V1 and V2 are closed, stopping the supply of purge gas to the treatment space 40 (at time t15). Shortly after time t15, NH 3 gas is supplied to the treatment space 40, and step S3 described in FIG. 3 starts (at time t16). On the other hand, the purge gas is stored in tanks 54B and 54F. After that, the supply of NH 3 gas to the treatment space 40 stops, and step S4 described in FIG. 4 starts (at time t17). Shortly after time t17, valves V1 and V2 open and purge gas is supplied to the treatment space 40, and the opening degree of valve V increases to become the opening degree A2 (at time t18). The pressure in the treatment space 40 decreases, and purging in the treatment space 40 proceeds.

[0055] Then the opening degree of valve V decreases to become the opening degree A1 (at time t19), and subsequently, valves V1 and V2 are closed, stopping the supply of purge gas to the treatment space 40 (at time t20). Shortly after time t20, the supply of TiCl 4 gas to the treatment space 40 is restarted, and step S1 starts again (at time t21). Then, steps S2 to S4 are performed. By repeating these steps S1 to S4 a predetermined number of times, the TiN film 10 is formed as shown in FIG. 5.

[0056] Note that, in this comparative example, the purge time is longer than that in the example. Therefore, in order to prevent the pressure in the processing space 40 from deviating from the allowable range due to the supply of the purge gas, the opening degree of the valve V is changed midway during the period from the time t13 to the time t14 when the purge gas is supplied via the tanks 54B and 54F, and during the period from the time t18 to the time t19. However, a detailed description of this change is omitted.

[0057] By the way, as described so far, in the example, regarding the opening degree of the valve V, it is set to a relatively small first opening degree until midway through the step of supplying each film-forming gas, and is set to a second opening degree larger than the first opening degree from midway through the step to the next step. That is, in both steps S2 and S4, the opening degree of the valve V is increased in advance from the previous step. However, it is also possible to increase the opening degree of the valve V in advance only for one of steps S2 and S4 from the previous step. And for the step among steps S2 and S4 where the opening degree of the valve V is not increased in advance, the opening degree of the valve V may be increased during the execution of the step as in the comparative example.

[0058] Even when only one of steps S2 and S4 increases the opening degree of the valve V in advance, TiCl 4 molecule 11 and NH 3 Since one of molecule 12 is adsorbed in a large number in the plane of the wafer W and the other molecule is supplied, it is considered that the coverage of the formed TiN film 10 can be increased. However, in order to further increase the coverage, it is preferable to increase the opening degree of the valve V in advance from the previous step in both steps S2 and S4.

[0059] In the embodiment, at the end point of step S2 (time t4 when the supply of the purge gas is stopped), the opening degree of valve V starts to decrease to reach the opening degree A3. However, the end point of this step S2 and the point in time when the change of valve V starts are not limited to being the same, and there may be a slight deviation. Similarly, there may also be a slight deviation between the end point of step S4 (time t7 when the supply of the purge gas is stopped) and the point in time when the change of valve V starts.

[0060] Incidentally, it is not necessary to supply the purge gas via tanks 54B and 54F. However, in order to surely suppress the reaction between the TiCl gas in the gas phase of the processing space 40 and the NH gas, it is preferable to supply it via tanks 54B and 54F. Incidentally, although the case of forming a TiN film has been exemplified, the film to be formed in the present technology is not limited to the TiN film. For various other films that can be formed by the reaction between the source gas and the reaction gas, the present technology can form a film on a substrate with high coating properties based on the same principle as the formation of the TiN film. The substrate to be formed is not limited to the wafer W, and a film can be formed on any substrate. 4 gas and NH 3 gas. The disclosed embodiment should be considered to be illustrative in all respects and not restrictive. The above embodiment may be omitted, substituted, changed, and combined in various forms without departing from the scope and spirit of the appended claims.

[0061] Note that the disclosed embodiment should be considered to be illustrative in all respects and not restrictive. The above embodiment may be omitted, substituted, changed, and combined in various forms without departing from the scope and spirit of the appended claims.

[0062] [Evaluation Test] Hereinafter, the evaluation tests conducted in relation to the present technology will be described. · Evaluation Test 1 As Evaluation Test 1, for a plurality of wafers W, TiN films were formed on each of them by the processing of the comparative example or the processing of the example, and a test was conducted to verify the state of each TiN film. The purge time (the implementation time of each of Steps S2 and S4) was set to be changed for each wafer W. For the test by the processing of the comparative example, the purge time was set longer than that of the test by the processing of the example. The tests conducted by the processing of the comparative example are represented as Comparative Examples 1-1 and 1-2, and the tests conducted by the processing of the example are represented as Examples 1-1 to 1-4. Table 1 below summarizes the implementation time of each Step S in this Evaluation Test 1.

[0063]

Table 1

[0064] Regarding the test conditions in more detail, the number of cycles to be implemented is set to be the same among Comparative Examples 1-1 to 1-2 and Examples 1-1 to 1-4. Also, the temperature of the mounting table 31 during the processing of the wafer W (that is, the temperature of the wafer W) was set to the same temperature among Comparative Examples 1-1 to 1-2 and Examples 1-1 to 1-4. Also, regarding the supply amount of NH 3 gas to the processing container 21 in Step S3, it was set to be approximately the same amount among Comparative Examples 1-1 to 1-2 and Examples 1-1 to 1-4. Regarding the supply amount of TiCl 4 gas to the processing container 21 in Step S1, it was set such that the shorter the purge time of Step S2, the less the amount.

[0065] Table 2 below shows the test results of this Evaluation Test 1. Regarding the coating property of the TiN film on the surface of the wafer W, it was verified from TEM (Transmission Electron Microscope) images. Regarding the roughness, it is the measurement result by AFM (Atomic Force Microscope), and regarding the size of the grains of TiN in the film, it is the measurement result by XRD (X-ray Diffraction). Regarding the chlorine content, they are the measurement results by XPS (X-ray Photoelectron Spectroscopy) and SIMS (Secondary Ion Mass Spectrometry) respectively. Regarding the roughness, grain size, resistivity of the TiN film, and chlorine content by SIMS, the results based on the results of Comparative Example 1-1 are described.

[0066]

Table 2

[0067] In Table 2, for each example, they are listed in order such that the purge time becomes shorter as it goes downward. The downward arrow in the table indicates that when viewed in this order (that is, when viewed in order with the purge time gradually becoming shorter), the state of the film gradually changes towards the state described as Examples 1-4. Specifically, taking the roughness as an example, the arrow indicates that the shorter the purge time, the higher the smoothness.

[0068] As shown in the table, in terms of the covering property, Examples 1-2 and 1-4 are higher than Comparative Example 1-1. Therefore, from this Evaluation Test 1, it was confirmed that the covering property can be increased by shortening the purge time. For this reason, as described above, it is speculated that the film-forming method of the example capable of shortening the purge time while suppressing the reaction between gases in the gas phase is effective. Also, regarding the roughness of the film, the shorter the purge time, the better the result. Regarding the grain size, in Example 1-4 with the shortest purge time, it is smaller than other examples. The smaller the grain size, the denser the grains and the less likely the TiN film will be discontinuous as the TiN film. Therefore, even considering this grain size, the result is that it is preferable to shorten the purge time.

[0069] From the results regarding this covering property, roughness, and grain size, and the settings of Example 1-2, it can be seen that the execution times of Steps S2 and S4 in the example (time T2 or T4 shown in the chart of FIG. 12) are preferably 0.6 seconds or less. Also, considering the settings of Example 1-4, it can be seen that it is more preferable that the execution times of each of these Steps S2 and S4 are 0.1 seconds or less.

[0070] As shown in Table 2, the resistance value increases as the purge time shortens, but even in Example 1-4 with the shortest purge time, it only slightly increased compared to Comparative Example 1-1, and it was at a level that has no practical impact. This increase in the resistance value is considered to be affected by the reduction in grain size and the slight increase in the chlorine content in the film.

[0071] · Evaluation Test 2 In this evaluation test, the film thicknesses of Comparative Example 2 and Example 2 with respect to the number of cycles were evaluated. Comparative Example 2 and Example 2 were tests conducted under the same conditions as Comparative Example 1-1 and Example 1-4 of Evaluation Test 1, respectively. Figure 14 is a graph showing the results of this test, and shows the results of Comparative Example 2, the results of Example 2, and the regression lines obtained from each of the results. From the graph, it was confirmed that in order to make the film thickness of the TiN film the desired size, a larger number of cycles is required for Comparative Example 2 than for Example 2. That is, if the number of cycles is the same, the film thickness of the TiN film is larger for Example 2 than for Comparative Example 2. And as shown in Evaluation Test 1, the time required for one cycle is shorter for Example 2 than for Comparative Example 2. Therefore, from the results of this Evaluation Test 2, it was shown that according to the film formation method of the example, the film formation rate (the increase amount of the film thickness per unit time) can be increased, and the throughput of the film formation apparatus 2 can be increased.

[0072] · Evaluation Test 3 Evaluation Test 3 was conducted to verify whether the reason for the increase in the film formation rate of the film formation method of the example in Evaluation Test 2 was not the result of film formation by CVD due to the reaction between TiCl 4 gas and NH 3 gas. Generally, when film formation is performed by the above CVD, the higher the temperature of the wafer W, the higher the film formation rate. Therefore, in Evaluation Test 3, when performing the film formation process under substantially the same processing conditions as Comparative Example 1-1, Example 1-1, 1-2, and 1-4 in Evaluation Test 1, the combination of the temperature of the mounting table 31 during the process (which is also the temperature of the wafer W) and the number of cycles was changed for each wafer W. Then, for each wafer W processed under each processing condition, the cycle rate obtained by dividing the film thickness (unit: Å) of the TiN film by the number of cycles was calculated, and the above verification was performed by examining the relationship between this cycle rate and the temperature of the mounting table 31. The test conducted under substantially the same processing conditions as Comparative Example 1-1 is designated as Comparative Example 3, and the tests conducted under substantially the same processing conditions as Example 1-1, 1-2, and 1-4 are designated as Example 3-1, 3-2, and 3-3, respectively.

[0073] In this evaluation test 3, in order to suppress the influence of the implementation time of step S3 (i.e., nitriding time) being short on the film thickness of the TiN film, the implementation time of step S3 was set longer than the implementation time of step S3 in evaluation test 1. Specifically, regarding the implementation time of this step S3, it was set to 15 seconds when nitriding was expected to be generally saturated based on the results of a separately conducted confirmation test. And the temperature of the mounting table 31 was set to 370°C, 450°C, or 500°C, and the number of cycles was set to 30, 40, and 50 respectively for each of these temperatures, and the wafer W was processed. Thus, except for the time of step S3, the temperature of the mounting table 31, and the number of cycles, the processing conditions of comparative example 3, examples 3-1, 3-2, and 3-3 are the same as the processing conditions of comparative example 1-1, examples 1-1, 1-2, and 1-4 respectively.

[0074] FIG. 15 is a graph showing the results of this evaluation test, and shows the change in the cycle rate with respect to the temperature of the mounting table 31. In the graph, the regression lines obtained from the results of comparative example 3, examples 3-1, 3-2, and 3-3 are shown respectively, and the slopes of these regression lines are generally the same. That is, according to this figure, it is confirmed that in comparative example 3 where CVD film formation is not assumed because a sufficient long-time purge is performed, and in examples 3-1, 3-2, and 3-3, the cycle rate increases to the same extent as the temperature of the mounting table 31 rises. Therefore, it is presumed that CVD film formation does not occur in examples 3-1 to 3-3 either, similar to comparative example 3-1. Also, at each temperature, as the purge time became shorter from comparative example 3 to example 3-3, the cycle rate increased. For this reason, in the film formation method of the present disclosure, it was confirmed that the cycle rate increases as the purge time becomes shorter.

[0075] · Supplementary test for evaluation test 3 A confirmation test 3 was conducted to obtain the relationship between the temperature of the mounting table 31 and the film thickness by a film forming apparatus for forming a TiN film on the wafer W by CVD. The graph in Fig. 16 shows the results of the confirmation test 3 and the results of Example 3-3 of the evaluation test. The film thickness increase rate shown on the vertical axis of the graph is a value obtained by dividing the film thickness (unit: Å) of the TiN film formed on the wafer W by the time (unit: second) during which the film forming gas was supplied. Note that, for Example 3-3, the time during which the film forming gas was supplied is the time when Steps S1 and S3 were performed. If film formation was performed by performing 100 cycles, it is [the execution time of Step S1 (0.9 seconds) + the execution time of Step S3 (15 seconds)] × 100.

[0076] As shown in this graph, compared with the results of the confirmation test 3, in Example 3-3, the increase amount of the film thickness increase rate with respect to the increase amount of the temperature of the mounting table 31 is low. From the results of this supplementary test as well, it is presumed that film formation by CVD is not performed in Example 3-3. Therefore, it is presumed that film formation by CVD is not performed for each of the other examples in which a regression line with a generally aligned slope is shown with respect to the regression line of Example 3-3 in Fig. 15. In the graph of Fig. 15, it is presumed that the cycle rate has increased due to the increase in the temperature of the mounting table 31 for each example because nitridation was insufficient and nitridation was promoted by heat. From the results of the evaluation tests 1 to 3 described above, it can be seen that according to the film forming method of the present disclosure, the cycle rate is improved by suppressing film formation by CVD and suppressing the desorption of the film forming gas from the wafer W.

[0077] · Evaluation Test 4 In this evaluation test, by simulation, for each of the processing of the comparative example and the processing of the example, the transition of the state of the processing space 40 in the gas phase and the state of the molecules containing Ti on the surface of the wafer W was verified. As Comparative Example 4 in this Evaluation Test 4, the same gases were supplied in the same manner as Comparative Example 1-1, except that the execution times of Steps S2 and S4 in Comparative Example 1-1 were both set to 3.5 seconds. Also, as Example 4 in this Evaluation Test 4, the same gases were supplied in the same manner as Example 1-4.

[0078] In the simulation, the processing space 40 was set as a cylindrical space with a diameter of 320 mm and a height of 7.5 mm. And the temperature of the processing space 40 was set to 370 °C and the pressure was set to 400 Pa (3 Torr) respectively. Regarding the supply flow rate per unit time of the gas in the standard state of steps S1 and S3, the NH 3 gas was set to about three times that of the TiCl 4 gas in step S1, and the flow rate of the mutual N2 gas was made the same. Regarding the supply flow rate per unit time of the gas in the standard state of steps S2 and S4, they were made substantially the same. And for each gas supplied to the processing space 40, the flow rate reached a predetermined flow rate simultaneously when the supply started, the predetermined flow rate was maintained during the supply, and the flow rate became 0 simultaneously when the supply ended. That is, when represented as a graph with time on the horizontal axis and the flow rate of the gas supplied to the processing space 40 on the vertical axis respectively, it was set so that a rectangular waveform was drawn.

[0079] FIG. 17 is a graph showing the simulation results of Comparative Example 4, and FIG. 18 is a graph showing the simulation results of Example 4. These graphs of FIGS. 17 and 18 show the transition of the molar fraction of each of the TiCl 4 molecules and NH 3 molecules for all the molecules contained in the gas phase, and the transition of the molar fraction of each of the TiCl 2 molecules and the physically adsorbed TiCl 4 molecules for all the molecules on the surface of the wafer W set at the bottom of the processing space 40. In both figures, the time axis on the horizontal axis is marked at 2-second intervals.

[0080] Note that the TiCl 2 molecules are the molecules contained in the region where physical adsorption of TiCl 4 molecules has not occurred. Therefore, also from the transition of the molar fraction of these TiCl 2 molecules, the TiCl 4The change in the physical adsorption amount of the molecules will be represented. Also, although the changes in the respective mole fractions are shown by different line types in the graphs of each figure, when the actually obtained simulation results are precisely represented in the drawings, the lines overlap and it becomes difficult to understand the change in the mole fraction. Therefore, for such parts that originally overlap, the lines are slightly separated and shown.

[0081] According to the results of Comparative Example 4 in FIG. 17, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero. 4 When the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero. 4 When the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero. 2 When the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero. 4 When the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero. 4 When the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero. 2 When the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero. 3 When the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero. 4 When the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases (the mole fraction of TiCl molecules decreases). However, when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W rapidly decreases (the mole fraction of TiCl molecules rapidly increases). And when step S3 is started and the mole fraction of NH increases, the mole fraction of the physically adsorbed TiCl molecules has become zero.

[0082] According to the results of Example 4 in FIG. 18, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases as in Comparative Example 4. And when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W decreases, but with a part of the physical adsorption of TiCl molecules maintained, the supply of NH gas in step S3 is carried out, and as a result, the mole fraction of NH gas in the gas phase increases. Thus, in Example 4, a film formation utilizing physical adsorption that was not carried out in Comparative Example 4 was achieved. 4 According to the results of Example 4 in FIG. 18, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases as in Comparative Example 4. And when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W decreases, but with a part of the physical adsorption of TiCl molecules maintained, the supply of NH gas in step S3 is carried out, and as a result, the mole fraction of NH gas in the gas phase increases. Thus, in Example 4, a film formation utilizing physical adsorption that was not carried out in Comparative Example 4 was achieved. 4 According to the results of Example 4 in FIG. 18, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases as in Comparative Example 4. And when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W decreases, but with a part of the physical adsorption of TiCl molecules maintained, the supply of NH gas in step S3 is carried out, and as a result, the mole fraction of NH gas in the gas phase increases. Thus, in Example 4, a film formation utilizing physical adsorption that was not carried out in Comparative Example 4 was achieved. 4 According to the results of Example 4 in FIG. 18, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases as in Comparative Example 4. And when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W decreases, but with a part of the physical adsorption of TiCl molecules maintained, the supply of NH gas in step S3 is carried out, and as a result, the mole fraction of NH gas in the gas phase increases. Thus, in Example 4, a film formation utilizing physical adsorption that was not carried out in Comparative Example 4 was achieved. 4 According to the results of Example 4 in FIG. 18, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases as in Comparative Example 4. And when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W decreases, but with a part of the physical adsorption of TiCl molecules maintained, the supply of NH gas in step S3 is carried out, and as a result, the mole fraction of NH gas in the gas phase increases. Thus, in Example 4, a film formation utilizing physical adsorption that was not carried out in Comparative Example 4 was achieved. 4 According to the results of Example 4 in FIG. 18, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases as in Comparative Example 4. And when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W decreases, but with a part of the physical adsorption of TiCl molecules maintained, the supply of NH gas in step S3 is carried out, and as a result, the mole fraction of NH gas in the gas phase increases. Thus, in Example 4, a film formation utilizing physical adsorption that was not carried out in Comparative Example 4 was achieved. 3 According to the results of Example 4 in FIG. 18, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases as in Comparative Example 4. And when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W decreases, but with a part of the physical adsorption of TiCl molecules maintained, the supply of NH gas in step S3 is carried out, and as a result, the mole fraction of NH gas in the gas phase increases. Thus, in Example 4, a film formation utilizing physical adsorption that was not carried out in Comparative Example 4 was achieved. 3 According to the results of Example 4 in FIG. 18, when the mole fraction of TiCl in the gas phase increases due to the implementation of step S1, the mole fraction of TiCl molecules physically adsorbed on the wafer W also increases as in Comparative Example 4. And when step S1 ends and the mole fraction of TiCl molecules in the gas phase decreases, the mole fraction of TiCl molecules physically adsorbed on the wafer W decreases, but with a part of the physical adsorption of TiCl molecules maintained, the supply of NH gas in step S3 is carried out, and as a result, the mole fraction of NH gas in the gas phase increases. Thus, in Example 4, a film formation utilizing physical adsorption that was not carried out in Comparative Example 4 was achieved.

[0083] In Example 4, after the completion of Step S1, Step S2 is started and the molar fraction of TiCl in the gas phase 4 molecules decreases to 0, and then Step S3 is started and the molar fraction of NH in the gas phase 3 molecules increases from 0. Similarly, after the molar fraction of NH in the gas phase 3 molecules decreases to 0, Step S1 is started and the molar fraction of TiCl in the gas phase 4 molecules increases from 0. Therefore, in this Example 4, although the purge times for Steps S2 and S4 are as short as 0.1 second each, it is expected that the mixing of TiCl 4 and NH 3 in the gas phase can be avoided, and film formation by CVD reaction can be avoided.

Explanation of Reference Numerals

[0084] V valve W wafer 10 TiN film 13 TiN molecules 21 processing container 28 exhaust passage

Claims

1. a film formation process in which a source gas serving as a film formation source and a reaction gas which reacts with the source gas to generate a reaction product are alternately and repeatedly supplied into a processing vessel, and a film of the reaction product is formed on a substrate in the processing vessel; a purging step of supplying a purge gas into the processing vessel to purge an atmosphere in the processing vessel during each purge period between a first period in which one of the source gas and the reaction gas is supplied into the processing vessel and a second period in which the other of the source gas and the reaction gas is subsequently supplied into the processing vessel; an opening degree changing process of a valve that is provided in an exhaust path that exhausts the inside of the processing vessel, the opening degree of the valve being increased to increase an amount of exhaust from the inside of the processing vessel, the opening degree of the valve being set to a first opening degree until a middle of one of the first period and the second period, and then changing the opening degree to a second opening degree that is larger than the first opening degree from the middle of the one period to a next purge period; A film forming method comprising the steps of:

2. the first period is a period during which the source gas is supplied into the processing chamber, and the second period is a period during which the reaction gas is supplied into the processing chamber, The opening degree changing step includes: setting the valve to the first opening degree until a first point in time during the first period, and setting the valve to the second opening degree from the first point in time until a next purge period; setting the valve to the first opening degree until a second point in the second period, and setting the valve to the second opening degree from the second point in the second period until a next purge period; The method of forming a film according to claim 1 , comprising:

3. supplying the purge gas to a tank provided in a flow path upstream of the gas supply valve in a state in which the gas supply valve is closed, and storing the purge gas in the tank; The purging step includes:

3. The method of claim 2, further comprising the step of supplying the purge gas from the tank into the processing vessel by opening the gas supply valve during each purge period.

4. 3. The film forming method according to claim 2, wherein the purge period following the first period is shorter than the first period.

5. 5. The film forming method according to claim 4, wherein the length of the purge period following the first period is 0.6 seconds or less.

6. 3. The film forming method according to claim 2, wherein the purge period following the second period is shorter than the second period.

7. 7. The film forming method according to claim 6, wherein the length of the purge period following the second period is 0.6 seconds or less.

8. 3. The film forming method according to claim 2, wherein a length from a start point of the first period to the first point in time is greater than a length from the first point in time to an end point of the first period.

9. The film forming method according to claim 2 , wherein a length from a start point of the second period to the second point in time is greater than a length from the second point in time to an end point of the second period.

10. 2. The method according to claim 1, wherein said source gas is titanium tetrachloride gas, said reactive gas is ammonia gas, and said film is a titanium nitride film.

11. a film formation process in which a source gas serving as a film formation source and a reaction gas which reacts with the source gas to generate a reaction product are alternately and repeatedly supplied into a processing vessel, and a film of the reaction product is formed on a substrate in the processing vessel; a purging step of supplying a purge gas into the processing vessel to purge an atmosphere in the processing vessel during each purge period between a first period in which one of the source gas and the reaction gas is supplied into the processing vessel and a second period in which the other of the source gas and the reaction gas is subsequently supplied into the processing vessel; a step included in the film forming step, in which one of the source gas and the reaction gas supplied into the processing vessel during the first period is physically adsorbed on the substrate, supplying the other of the source gas and the reaction gas into the processing vessel during the second period following the first period, thereby generating the reaction product on the substrate; A film forming method comprising the steps of:

12. a processing vessel for storing the substrate; a film-forming gas supply mechanism that alternately and repeatedly supplies into the processing chamber a source gas that is a film-forming source and a reaction gas that reacts with the source gas to produce a reaction product in order to form a film of a reaction product on the substrate; a purge gas supply mechanism that supplies a purge gas into the processing vessel to purge an atmosphere in the processing vessel during each purge period between a first period in which one of the source gas and the reaction gas is supplied into the processing vessel and a second period in which the other of the source gas and the reaction gas is supplied into the processing vessel; an exhaust path for exhausting the inside of the processing vessel; a valve provided in the exhaust path, the valve opening of which increases an amount of exhaust from within the processing vessel; a control unit that outputs a control signal so that the opening degree of the valve is a first opening degree until a midpoint of one of the first period and the second period, and is changed to a second opening degree larger than the first opening degree from the midpoint of the one period to a next purge period; A film forming apparatus comprising:

Images