Deposition method and deposition apparatus

Abstract

To provide a technology that can control the crystallinity of thin films.SOLUTION: A deposition method according to an aspect of the present disclosure is a deposition method for forming a thin film on a substrate, and comprises: (a) a step for adsorbing raw material gas on a substrate; (b) a step for supplying oxidizing gas to the substrate to oxidize the material gas; (c) a step for exposing the substrate to a plasma generated from a plasma gas containing argon gas and oxygen gas; and (d) a step for repeating the above steps from (a) to (c) in this order, and the step (c) includes controlling the crystallinity of the thin film formed on the substrate by adjusting the plasma output.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] There is known a technique in which a hafnium zirconium-based film is deposited on a substrate, and then the substrate is heat-treated to crystallize the hafnium zirconium-based film (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-531661 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can control the crystallinity of a thin film. [Means for solving the problem]

[0005] A film formation method according to one embodiment of the present disclosure is a film formation method for forming a thin film on a substrate, comprising the steps of (a) adsorbing a raw material gas onto a substrate, (b) supplying an oxidizing gas to the substrate and oxidizing the raw material gas, (c) exposing the substrate to plasma generated from a plasma gas containing argon gas and oxygen gas, and (d) repeating steps (a) to (c) in this order, wherein step (c) includes controlling the crystallinity of the thin film formed on the substrate by adjusting plasma output. Effect of the Invention

[0006] According to the present disclosure, the crystallinity of a thin film can be controlled. [Brief description of the drawings]

[0007] [Figure 1] 2 is a flowchart illustrating a film forming method according to an embodiment. [Diagram 2] 1 is a schematic cross-sectional view showing a film forming apparatus according to an embodiment. [Diagram 3] 3 is a schematic perspective view showing a configuration inside a vacuum chamber of the film forming apparatus of FIG. 2. [Figure 4] 3 is a schematic plan view showing the configuration inside a vacuum chamber of the film forming apparatus of FIG. 2. [Diagram 5] 3 is a schematic cross-sectional view taken along a concentric circle of a rotation table of the film forming apparatus of FIG. 2. [Figure 6] 3 is another schematic cross-sectional view of the film forming apparatus of FIG. 2. [Figure 7] FIG. 2 is a schematic cross-sectional view showing a remote plasma unit. [Figure 8] FIG. 2 is a plan view showing the lower surface of the shower head of the remote plasma unit. [Figure 9] FIG. 1 is a diagram showing the relationship between the thickness of a zirconium oxide film and the peak intensity of XRD. [Figure 10] FIG. 2 is a diagram showing the crystal phase ratio of a zirconium oxide film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all of the accompanying drawings, the same or corresponding members or parts are designated by the same or corresponding reference numerals, and duplicated descriptions will be omitted.

[0009] [Film formation method] A film forming method according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a flowchart showing the film forming method according to the embodiment. As shown in Fig. 1, the film forming method according to the embodiment includes a preparation step S1, an adsorption step S2, a purging step S3, an oxidation step S4, a crystallinity control step S5, a purging step S6, and a determination step S7.

[0010] The preparation step S1 includes preparing a substrate. The substrate may be a semiconductor wafer such as a silicon wafer. The substrate may have a recess such as a trench or a hole on the surface.

[0011] The adsorption step S2 is performed after the preparation step S1. The adsorption step S2 includes supplying a source gas to the surface of the substrate and allowing the source gas to be adsorbed on the surface of the substrate. The adsorption step S2 may include maintaining the substrate at a predetermined temperature. The predetermined temperature can be set according to the application.

[0012] The source gas is, for example, a zirconium (Zr)-containing gas. The source gas may be an aluminum (Al)-containing gas, a zirconium-containing gas, a hafnium (Hf)-containing gas, a lanthanum (La)-containing gas, or a mixed gas containing two or more of these.

[0013] The purging step S3 is performed after the adsorption step S2. The purging step S3 includes supplying an inert gas to the surface of the substrate to purge the surface of the substrate. The inert gas may be, for example, nitrogen (N2) gas. The inert gas may be a rare gas such as helium (He) gas or argon (Ar) gas.

[0014] The oxidation step S4 is performed after the purging step S3. The oxidation step S4 includes supplying an oxidation gas to the surface of the substrate to oxidize the source gas adsorbed on the surface of the substrate, thereby forming an oxide film on the surface of the substrate.

[0015] The oxidation step S4 may include oxidizing the source gas by thermal oxidation. In this case, it is easy to control the crystallinity of the oxide film in the crystallinity control step S5 performed following the oxidation step S4. Thermal oxidation means that the substrate is heat-treated in an atmosphere containing an oxidizing gas without using plasma to oxidize the source gas. The oxidation step S4 may include maintaining the substrate at a predetermined temperature. The predetermined temperature may be the same as the temperature of the substrate in the adsorption step S2.

[0016] The oxidizing gas may be, for example, ozone (O3) gas. The oxidizing gas may be ozone gas, oxygen (O2) gas, water (H2O), hydrogen peroxide (H2O2) gas, or a mixed gas containing two or more of these.

[0017] The oxide film is, for example, a zirconium oxide film. The oxide film may be any of various high-k films (high dielectric constant films). The high-k film means a film having a higher relative dielectric constant than a silicon oxide film. The high-k film may be an aluminum oxide film, a hafnium oxide film, a zirconium oxide film, a lanthanum oxide film, or a laminated film of two or more of these.

[0018] The crystallinity control step S5 is performed after the oxidation step S4. The crystallinity control step S5 includes exposing the substrate to plasma generated from a plasma gas containing argon gas and oxygen gas. The crystallinity control step S5 includes controlling the crystallinity of the oxide film formed on the substrate by adjusting the plasma output when generating the plasma. The plasma output means the output of the plasma source used when generating the plasma. For example, the crystallinity of the oxide film can be reduced by increasing the plasma output above a reference value. For example, the crystallinity of the oxide film can be increased by decreasing the plasma output below a reference value. The crystallinity control step S5 may include maintaining the substrate at a predetermined temperature. The predetermined temperature may be the same temperature as the temperature of the substrate in the adsorption step S2.

[0019] The plasma gas is, for example, a mixed gas of argon gas and oxygen gas. Hereinafter, the mixed gas of argon gas and oxygen gas is also referred to as Ar / O2 gas. The plasma gas may further contain another rare gas such as helium gas.

[0020] The plasma is generated, for example, by a remote plasma unit. In this case, radicals and ions contained in the plasma generated from the plasma gas easily reach deep positions in the recesses of the substrate. This makes it easy to control the crystallinity of the oxide film formed in the deep positions of the recesses. However, the plasma may be generated by a direct plasma unit. The remote plasma unit and the direct plasma unit include a plasma source. For example, an inductively coupled plasma, a capacitively coupled plasma, or a surface wave plasma can be used as the plasma source.

[0021] The purging step S6 is carried out after the crystallinity control step S5. The purging step S6 includes supplying an inert gas to the surface of the substrate to purge the surface of the substrate. The inert gas may be the same as the inert gas used in the purging step S3.

[0022] The determination step S7 is performed after the purging step S6. The determination step S7 includes determining whether the adsorption step S2 to the purging step S6 have been performed the set number of times. If the number of times has not reached the set number (NO in the determination step S7), the adsorption step S2 to the purging step S6 are performed again. If the number of times has reached the set number (YES in the determination step S7), the process ends. In this manner, the process of performing the adsorption step S2 to the purging step S6 in this order is repeated multiple times until the number of times has reached the set number.

[0023] According to the film forming method of the embodiment described above, the adsorption step S2, the oxidation step S4, and the crystallinity control step S5 are repeatedly performed in this order, and the crystallinity of the oxide film formed on the substrate is controlled by adjusting the plasma output in the crystallinity control step S5. In this case, the crystallinity of the oxide film can be easily controlled.

[0024] The plasma output in the crystallinity control step S5 may be changed while the process of performing the adsorption step S2 to the purging step S6 in this order is repeated multiple times. In this case, the crystallinity of the oxide film can be controlled in the thickness direction.

[0025] [Film forming equipment] The overall configuration of the film formation apparatus according to the embodiment will be described with reference to Figs. 2 to 8. Fig. 2 is a schematic cross-sectional view showing the film formation apparatus according to the embodiment. Fig. 3 is a schematic perspective view showing the configuration inside the vacuum vessel 1 of the film formation apparatus of Fig. 2. Fig. 4 is a schematic plan view showing the configuration inside the vacuum vessel 1 of the film formation apparatus of Fig. 2. Fig. 2 is a cross-sectional view taken along line I-I' in Fig. 4. The top plate 11 is omitted from Figs. 3 and 4.

[0026] As shown in FIGS. 2 to 4, the film forming apparatus according to the embodiment includes a vacuum vessel 1 and a rotary table 2. As shown in FIG.

[0027] The vacuum vessel 1 is a flat vessel having a substantially circular planar shape. The vacuum vessel 1 is a processing chamber for performing a film formation process on the surface of a substrate W accommodated therein. The substrate W may be a semiconductor wafer. The vacuum vessel 1 has a top plate 11 and a vessel body 12. The top plate 11 is disposed on the upper surface of the vessel body 12 so as to be airtightly and detachably attached thereto via a sealing member 13 such as an O-ring. The vessel body 12 has a cylindrical shape with a bottom.

[0028] The rotary table 2 is provided in the vacuum vessel 1. The rotary table 2 has a center of rotation at the center of the vacuum vessel 1. The rotary table 2 is fixed at the center to a cylindrical core portion 21. The core portion 21 is fixed to the upper end of a rotary shaft 22 extending in the vertical direction. The rotary shaft 22 penetrates the bottom portion 14 of the vacuum vessel 1. The lower end of the rotary shaft 22 is attached to a driving portion 23. The driving portion 23 rotates the rotary shaft 22 around the vertical axis. The rotary shaft 22 and the driving portion 23 are housed in a cylindrical case body 20 with an open upper surface. The case body 20 has a flange provided on the upper surface airtightly attached to the lower surface of the bottom portion 14 of the vacuum vessel 1. This maintains an airtight state between the internal atmosphere of the case body 20 and the external atmosphere.

[0029] A plurality of (five in the illustrated example) circular recesses 24 are provided on the upper surface of the turntable 2 along the rotation direction (circumferential direction). A substrate W is placed in each recess 24. FIG. 4 shows the substrate W in only one recess 24. The recess 24 has an inner diameter slightly larger than the diameter of the substrate W and a depth approximately equal to the thickness of the substrate W. Therefore, when the substrate W is accommodated in the recess 24, the upper surface of the substrate W and the upper surface of the turntable 2 (the area on which the substrate W is not placed) are at the same height. A through hole (none of which is illustrated) through which, for example, three lift pins pass is formed in the bottom surface of the recess 24. The three lift pins support the lower surface of the substrate W and raise and lower the substrate W relative to the recess 24.

[0030] Above the turntable 2, gas nozzles 31, 32, 41, 42 and a gas discharge unit 93d of a remote plasma unit 90 described later are arranged at intervals from each other in the rotation direction of the turntable 2 (arrow A in FIG. 4). In the illustrated example, the gas discharge unit 93d, gas nozzle 41, gas nozzle 31, gas nozzle 42, and gas nozzle 32 are arranged in this order clockwise (rotation direction of the turntable 2) from a transfer port 15 described later. Each of the gas nozzles 31, 32, 41, 42 is formed of, for example, quartz. Each of the gas nozzles 31, 32, 41, 42 has gas introduction ports 31a, 32a, 41a, 42a, which are base ends, fixed to the outer circumferential wall of the vessel body 12. As a result, each of the gas nozzles 31, 32, 41, 42 is introduced into the vacuum vessel 1 from the outer circumferential wall of the vacuum vessel 1 and is attached so as to extend horizontally with respect to the turntable 2 along the radial direction of the vessel body 12. A gas supply pipe 92 of the remote plasma unit 90, which is connected to a gas discharge part 93d described later, may be connected to the gas introduction port 33a.

[0031] The gas nozzle 31 is connected to a source gas supply source 130 via a pipe 110, a flow rate controller 120, etc. The source gas is, for example, a zirconium-containing gas. The source gas may be an aluminum-containing gas, a zirconium-containing gas, a hafnium-containing gas, a lanthanum-containing gas, or a mixed gas containing two or more of these.

[0032] The gas nozzle 32 is connected to an oxidizing gas supply source 131 via a pipe 111, a flow rate controller 121, etc. The oxidizing gas is, for example, ozone gas. The oxidizing gas may be ozone gas, oxygen gas, water, hydrogen peroxide gas, or a mixed gas containing two or more of these.

[0033] The gas supply pipe 92 of the remote plasma unit 90 is connected to a plasma gas supply source 132 via a pipe 112, a flow rate controller 122, etc. The plasma gas includes argon gas and oxygen gas. The plasma gas is, for example, Ar / O2 gas. The plasma gas may further include another rare gas, such as helium gas.

[0034] The gas nozzles 41 and 42 are both connected to a separation gas supply source (not shown) via piping and flow control valves (not shown). The separation gas is, for example, argon gas. The separation gas may be another rare gas such as helium gas, or may be nitrogen gas.

[0035] FIG. 5 is a schematic cross-sectional view taken along a concentric circle of the turntable 2 of the film forming apparatus of FIG. 2, and shows a cross-section of the vacuum vessel 1 taken along a concentric circle of the turntable 2 from gas nozzle 31 to gas nozzle 32. As shown in FIG.

[0036] As shown in FIG. 5, the gas nozzles 31 and 32 are provided with a plurality of discharge holes 35. The plurality of discharge holes 35 are arranged at intervals of, for example, 10 mm along the length direction of the gas nozzles 31 and 32. Each discharge hole 35 opens toward the turntable 2. The gas nozzle 31 discharges the raw material gas from the plurality of discharge holes 35 toward the upper surface of the turntable 2. The region below the gas nozzle 31 becomes an adsorption region P1 for adsorbing the raw material gas onto the substrate W. The gas nozzle 32 discharges an oxidizing gas from the plurality of discharge holes 35 toward the upper surface of the turntable 2. The region below the gas nozzle 32 becomes an oxidation region P2 in which the raw material gas adsorbed onto the substrate W in the adsorption region P1 is oxidized to form an oxide film. The region below the gas discharge portion 93d becomes a plasma region P3 in which the oxide film formed in the oxidation region P2 is exposed to plasma generated from a plasma gas. A remote plasma unit 90 is provided above the plasma region P3. In FIG. 4, the remote plasma unit 90 is simplified and shown by a broken line. The remote plasma unit 90 will be described later.

[0037] Two convex portions 4 are provided in the vacuum vessel 1. The convex portions 4, together with the gas nozzles 41 and 42, constitute a separation region D. The convex portions 4 have a sectorial planar shape with the top cut into an arc. The inner arc of the convex portions 4 is connected to the protrusions 5 (described later). The outer arc of the convex portions 4 is disposed so as to follow the inner peripheral surface of the vessel body 12.

[0038] The convex portion 4 is attached to the lower surface of the top plate 11 so as to protrude toward the rotary table 2. As a result, in the vacuum vessel 1, there are a flat low ceiling surface (hereinafter referred to as a "first ceiling surface 44") which is the lower surface of the convex portion 4, and a ceiling surface (hereinafter referred to as a "second ceiling surface 45") which is located on both sides of the first ceiling surface 44 in the circumferential direction and is higher than the first ceiling surface 44. The first ceiling surface 44 has a fan-shaped planar shape with an apex cut in an arc shape. The convex portion 4 is provided with a groove portion 43 extending in the radial direction at the center in the circumferential direction. The groove portion 43 accommodates a gas nozzle 42. The other convex portion 4 is also provided with a similar groove portion 43. The groove portion 43 accommodates a gas nozzle 41. The gas nozzles 31 and 32 are provided in the space below the second ceiling surface 45. The gas nozzles 31 and 32 are provided in the vicinity of the substrate W, away from the second ceiling surface 45. The gas nozzle 31 is provided in a space 481 on the right side below the second ceiling surface 45. The gas nozzle 32 is provided in a space 482 on the left side below the second ceiling surface 45.

[0039] The gas nozzle 42 is provided with a plurality of discharge holes 42h. The plurality of discharge holes 42h are arranged along the longitudinal direction of the gas nozzle 42 at intervals of, for example, 10 mm. Each discharge hole 42h opens toward the turntable 2. The gas nozzle 42 discharges the separation gas from the plurality of discharge holes 42h toward the upper surface of the turntable 2. The gas nozzle 41 is similar to the gas nozzle 42.

[0040] The first ceiling surface 44 forms a narrow separation space H with respect to the turntable 2. When the separation gas is supplied from the multiple discharge holes 42h, the separation gas flows through the separation space H toward the space 481 and the space 482. At this time, since the volume of the separation space H is smaller than the volumes of the spaces 481 and 482, the pressure in the separation space H becomes higher than the pressure in the spaces 481 and 482 due to the separation gas. That is, a separation space H with a high pressure is formed between the spaces 481 and 482. The separation gas flowing out from the separation space H to the spaces 481 and 482 acts as a counter flow to the source gas from the adsorption region P1 and the oxidation gas from the oxidation region P2. As a result, the source gas and the oxidation gas are separated by the separation space H. Therefore, mixing of the source gas and the oxidation gas in the vacuum vessel 1 is suppressed.

[0041] The height h1 of the first ceiling surface 44 relative to the upper surface of the turntable 2 is set so that the pressure in the separation space H is higher than the pressure in the spaces 481, 482, taking into consideration the pressure inside the vacuum chamber 1 when forming a film on the substrate W, the rotation speed of the turntable 2, the amount of separation gas supplied, etc.

[0042] A protrusion 5 is provided on the underside of the top plate 11, surrounding the outer periphery of the core portion 21 to which the turntable 2 is fixed. The protrusion 5 is continuous with the portion of the convex portion 4 on the rotation center side. The underside of the protrusion 5 is formed at the same height as the first ceiling surface 44.

[0043] Fig. 6 is a cross-sectional view showing an area where the first ceiling surface 44 is provided. As shown in Fig. 6, a bent portion 46 is provided on the peripheral edge of the sector-shaped convex portion 4. The bent portion 46 is bent into an L-shape so as to face the outer end surface of the turntable 2. Similar to the convex portion 4, the bent portion 46 prevents the source gas and the oxidizing gas from entering from both sides of the separation region D, and prevents the source gas and the oxidizing gas from mixing with each other.

[0044] The inner peripheral wall of the container body 12 is formed in a vertical plane in the separation region D close to the outer peripheral surface of the bent portion 46 as shown in FIG. 6. The inner peripheral wall of the container body 12 is recessed outward from the portion facing the outer end surface of the turntable 2 to the bottom 14 in the portion other than the separation region D as shown in FIG. 2. Hereinafter, for convenience of explanation, the recessed portion having a generally rectangular cross-sectional shape is referred to as an exhaust region. Specifically, the exhaust region communicating with the adsorption region P1 is referred to as a first exhaust region E1, and the region communicating with the oxidation region P2 and the plasma region P3 is referred to as a second exhaust region E2. A first exhaust port 61 and a second exhaust port 62 are formed at the bottom of the first exhaust region E1 and the second exhaust region E2, respectively. The first exhaust port 61 and the second exhaust port 62 are connected to a vacuum pump 64 via an exhaust pipe 63. A pressure controller 65 is provided between the vacuum pump 64 and the exhaust pipe 63. 2, the first exhaust port 61 is shown, but the second exhaust port 62 is similar.

[0045] As shown in FIG. 2 and FIG. 6, a heater unit 7 is provided in the space between the turntable 2 and the bottom 14 of the vacuum vessel 1. The heater unit 7 heats the substrate W on the turntable 2 to a predetermined temperature determined by a process recipe via the turntable 2. An annular cover member 71 is provided below the periphery of the turntable 2. The cover member 71 divides the atmosphere from the space above the turntable 2 to the first exhaust region E1 and the second exhaust region E2 from the atmosphere in which the heater unit 7 is placed, thereby suppressing the intrusion of gas into the region below the turntable 2. The cover member 71 has an inner member 71a and an outer member 71b. The inner member 71a is provided so as to face the outer edge of the turntable 2 and the outer periphery side from below. The inner member 71a surrounds the heater unit 7 all around below the outer edge of the turntable 2 (and below a portion slightly outside the outer edge). The outer member 71b is provided between the inner member 71a and the inner circumferential surface of the vacuum vessel 1. The outer member 71b is provided below and in close proximity to the bent portion 46 formed on the outer edge portion of the convex portion 4 in the separation region D.

[0046] The bottom 14 at a location closer to the center of rotation than the space in which the heater unit 7 is disposed protrudes upward to approach the core 21 near the center of the lower surface of the turntable 2, forming a protruding portion 12a. A narrow space is formed between the protruding portion 12a and the core 21, and a narrow gap is formed between the inner peripheral surface of the through hole of the rotary shaft 22 penetrating the bottom 14 and the rotary shaft 22, and these narrow spaces communicate with the case body 20. A purge gas supply pipe 72 is provided in the case body 20. The narrow space is purged by the purge gas supplied from the purge gas supply pipe 72. A purge gas supply pipe 73 is provided in the bottom 14 of the vacuum vessel 1. A plurality of purge gas supply pipes 73 are provided below the heater unit 7 at predetermined angular intervals in the circumferential direction. FIG. 6 shows one purge gas supply pipe 73. The space in which the heater unit 7 is disposed is purged by the purge gas supplied from the purge gas supply pipe 73. The purge gas may be the same type of gas as the separation gas. A lid member 7a is provided between the heater unit 7 and the turntable 2. The lid member 7a circumferentially covers the area between the inner peripheral wall of the outer member 71b (the upper surface of the inner member 71a) and the upper end of the protrusion 12a. The lid member 7a prevents gas from entering the area where the heater unit 7 is provided. The lid member 7a is made of, for example, quartz.

[0047] A separation gas supply pipe 51 is connected to the center of the top plate 11. The separation gas supply pipe 51 supplies a separation gas to a space 52 between the top plate 11 and the core portion 21. The separation gas supplied to the space 52 is discharged toward the periphery along the surface of the turntable 2 on the substrate placement region side through a space 50, which is a narrow gap between the protrusion 5 and the turntable 2. The space 50 can be maintained at a higher pressure than the spaces 481 and 482 by the separation gas. Therefore, the space 50 prevents the source gas supplied to the adsorption region P1 and the oxidation gas supplied to the oxidation region P2 from mixing through the central region C. That is, the space 50 (or the central region C) functions similarly to the separation space H (or the separation region D).

[0048] A transfer port 15 is provided in a side wall of the vacuum vessel 1. The substrate W is transferred between an external transfer arm 10 and the turntable 2 via the transfer port 15. The transfer port 15 is opened and closed by a gate valve (not shown). The substrate W is transferred between the transfer arm 10 and a recess 24 located at a position facing the transfer port 15. For this reason, a transfer lift pin for penetrating the recess 24 and lifting the substrate W from its lower surface and a lift mechanism for the same (neither shown) are provided below the turntable 2 at a position corresponding to the transfer position.

[0049] 7 is a schematic cross-sectional view showing a remote plasma unit 90. The remote plasma unit 90 is provided in the plasma region P3 and faces the turntable 2. The remote plasma unit 90 has a plasma generating part 91, a gas supply pipe 92, a shower head 93, and piping 94. A gas nozzle may be used instead of the shower head 93.

[0050] The plasma generating unit 91 activates the plasma gas supplied from the gas supply pipe 92 by a plasma source. The plasma source is not particularly limited as long as it can activate the plasma gas. For example, an inductively coupled plasma, a capacitively coupled plasma, or a surface wave plasma can be used as the plasma source.

[0051] One end of the gas supply pipe 92 is connected to the plasma generating unit 91, and supplies plasma gas to the plasma generating unit 91. The other end of the gas supply pipe 92 is connected to a plasma gas supply source 132 in which plasma gas is stored, for example, via an opening / closing valve and a flow rate regulator.

[0052] The shower head 93 is connected to the plasma generating unit 91 via piping 94. The shower head 93 supplies the plasma gas activated in the plasma generating unit 91 into the vacuum vessel 1. The shower head 93 has a sector-shaped planar shape, and is pressed downward in the circumferential direction by a pressing member 95 formed along the outer edge of the sector-shaped planar shape. The pressing member 95 is fixed to the top plate 11 by bolts or the like (not shown). This makes the interior atmosphere of the vacuum vessel 1 airtight.

[0053] A plurality of outlet holes 93a are provided in the shower head 93. The activated plasma gas supplied to the shower head 93 is supplied to the space between the turntable 2 and the shower head 93 through the outlet holes 93a.

[0054] FIG. 8 is a plan view showing the lower surface of the shower head 93 of the remote plasma unit 90. As shown in FIG. 8, the downward protruding surface 93c may be provided in a band shape along the outer periphery of the lower surface 93b of the sector-shaped shower head 93. This makes it possible to prevent a drop in pressure on the outer periphery side of the plasma region P3 uniformly in the circumferential direction. The discharge holes 93a may be provided in the center of the circumferential direction of the lower surface 93b of the shower head 93 so as to extend in the radial direction. This makes it possible to supply the plasma gas while dispersing it from the center side of the turntable 2 to the outer periphery side. In the present application, a portion of the shower head 93 where the multiple discharge holes 93a are provided may be referred to as a gas discharge portion 93d.

[0055] In this manner, the remote plasma unit 90 supplies the activated plasma gas to the substrate W.

[0056] As shown in FIG. 2, the film forming apparatus according to the embodiment includes a control unit 100. The control unit 100 controls the operation of each unit of the film forming apparatus. The control unit 100 may be a computer. A computer program for controlling the operation of each unit of the film forming apparatus is stored in a medium 102. The medium 102 may be a flexible disk, a compact disk, a hard disk, a flash memory, a DVD, or the like. The program stored in the medium 102 is read into the storage unit 101 by a predetermined reading device and installed in the control unit 100.

[0057] [Operation of the Film Forming Apparatus] The operation of the film forming apparatus when carrying out the film forming method according to the embodiment will be described below, taking as an example a case where a zirconium oxide film is formed as a thin film.

[0058] First, the substrates W are placed in each of the five recesses 24 of the turntable 2 in the vacuum chamber 1 of the film forming apparatus. Specifically, a gate valve (not shown) of the film forming apparatus is opened, and the substrates W are transferred from the outside to the recesses 24 of the turntable 2 via the transfer port 15 by the transfer arm 10. The transfer of the substrates W is performed by lifting pins (not shown) moving up and down from the bottom side of the vacuum chamber 1 through through holes in the bottom surface of the recesses 24 when the recesses 24 are stopped at a position facing the transfer port 15. The transfer of the substrates W is performed by intermittently rotating the turntable 2, and the substrates W are placed in each of the five recesses 24 of the turntable 2.

[0059] Next, the inside of the vacuum vessel 1 is evacuated. Specifically, the gate valve is closed, and the inside of the vacuum vessel 1 is evacuated by the vacuum pump 64 to an achievable vacuum level.

[0060] Next, argon gas, which is a separation gas, is discharged at a predetermined flow rate from the gas nozzles 41 and 42 and the separation gas supply pipe 51, and argon gas, which is a purge gas, is discharged at a predetermined flow rate from the purge gas supply pipes 72 and 73. After this, a zirconium-containing gas, which is a raw material gas, is supplied from the gas nozzle 31, ozone gas, which is an oxidation gas, is supplied from the gas nozzle 32, and Ar / O2 gas, which is a plasma gas, is supplied from the gas supply pipe 92. In addition, the remote plasma unit 90 is operated. The remote plasma unit 90 generates plasma from the Ar / O2 gas. In addition, the pressure controller 65 controls the inside of the vacuum chamber 1 to a processing pressure set in advance. In addition, the heater unit 7 heats the substrate W while rotating the turntable 2 clockwise. The rotation speed of the turntable 2 and the temperature of the substrate W can be set according to the application.

[0061] By the rotation of the turntable 2, the substrate W passes through the adsorption region P1, the separation region D, the oxidation region P2, the plasma region P3, and the separation region D repeatedly in this order.

[0062] In the adsorption region P1, the adsorption step S2 is performed. In the adsorption region P1, a zirconium-containing gas is supplied from the gas nozzle 31 to the surface of the substrate W, and the zirconium-containing gas is adsorbed onto the surface of the substrate W.

[0063] A purge step S3 is performed in the separation region D. In the separation region D, argon gas is supplied from the gas nozzle 42 to the surface of the substrate W, and the surface of the substrate W is purged.

[0064] In the oxidation region P2, an oxidation step S4 is performed. In the oxidation region P2, ozone gas is supplied from the gas nozzle 32 to the surface of the substrate W, and the zirconium-containing gas adsorbed on the surface of the substrate W is oxidized to form a zirconium oxide film on the surface of the substrate W.

[0065] In the plasma region P3, the crystallinity control step S5 is performed. In the plasma region P3, the substrate W is exposed to plasma generated from Ar / O2 gas, thereby controlling the crystallinity of the zirconium oxide film. Specifically, the crystallinity of the zirconium oxide film is controlled by adjusting the plasma output when generating the plasma.

[0066] A purge step S6 is performed in the separation region D. In the separation region D, argon gas is supplied from the gas nozzle 41, and the surface of the substrate W is purged.

[0067] In this manner, as the turntable 2 rotates, the substrate W passes through the adsorption region P1, the separation region D, the oxidation region P2, the plasma region P3, and the separation region D repeatedly in this order, thereby forming a zirconium oxide film with controlled crystallinity on the surface of the substrate W.

[0068] Next, purging is performed. Specifically, the supply of zirconium-containing gas from the gas nozzle 31 is stopped, and the supply of ozone gas from the gas nozzle 32 is stopped. In addition, the supply of Ar / O2 gas to the remote plasma unit 90 and the remote plasma unit 90 are stopped, thereby stopping the supply of activated Ar / O2 gas from the gas discharge part 93d. As a result, argon gas is supplied at a predetermined flow rate from the gas nozzles 41, 42 and the separation gas supply pipe 51, and argon gas is supplied at a predetermined flow rate from the purge gas supply pipes 72, 73. As a result, the inside of the vacuum vessel 1 is purged with argon gas.

[0069] Next, the inside of the vacuum vessel 1 is opened to the atmosphere to return it to atmospheric pressure, and the substrate W on which the zirconium oxide film has been formed is taken out from the vacuum vessel 1.

[0070] According to the operation of the film forming apparatus described above, the adsorption step S2, the oxidation step S4, and the crystallinity control step S5 are repeatedly performed in this order on the substrate W in the vacuum chamber 1. Moreover, in the crystallinity control step S5, the plasma output of the remote plasma unit 90 is adjusted to control the crystallinity of the oxide film formed on the substrate.

[0071] [Example] The film forming method according to the embodiment was carried out using the film forming apparatus according to the embodiment.

[0072] In the embodiment, a zirconium-containing gas as a raw material gas was supplied from the gas nozzle 31, an oxidizing gas, ozone gas, was supplied from the gas nozzle 32, and a plasma gas, Ar / O2 gas, was supplied from the gas supply pipe 92. The remote plasma unit 90 was operated to generate plasma from the Ar / O2 gas. Then, by rotating the turntable 2, the substrate W was passed through the adsorption region P1, the separation region D, the oxidation region P2, the plasma region P3, and the separation region D in this order, thereby forming a zirconium oxide film on the surface of the substrate W. The ratio of the Ar / O2 gas was set to Ar:O2=5:3. In the crystallinity control step S5, the plasma output was set to three conditions: 3 kW, 4 kW, and 7.2 kW.

[0073] For comparison, a zirconium oxide film was formed on the surface of the substrate W in the example without operating the remote plasma unit 90 and supplying ozone gas instead of Ar / O 2 gas from the gas supply pipe 92.

[0074] Next, the film thickness and crystallinity of each zirconium oxide film formed were measured. The film thickness of the zirconium oxide film was calculated based on the cross-sectional image observed by a transmission electron microscope (TEM). The crystallinity of the zirconium oxide film was evaluated by X-ray diffraction (XRD) and ACOM (Automated Crystal Orientation Mapping)-TEM. When θ-2θ measurement was performed by the X-ray diffraction method, a peak derived from the tetragonal crystal of the zirconium oxide film appears at a diffraction angle of 2θ=30°. Therefore, the crystallinity of the zirconium oxide film was evaluated by measuring the peak intensity at a diffraction angle of 2θ=30°. In the ACOM-TEM method, a phase distribution diagram of the cross section of the zirconium oxide film was obtained, and the ratio of tetragonal crystal, orthorhombic crystal, and monoclinic crystal was obtained.

[0075] Fig. 9 is a diagram showing the relationship between the thickness of the zirconium oxide film and the peak intensity of XRD. In Fig. 9, the horizontal axis indicates the thickness [nm] of the zirconium oxide film measured by TEM, and the vertical axis indicates the peak intensity [cps] of the zirconium oxide film at 2θ=30° measured by XRD. In Fig. 9, circles indicate the results when the plasma output was 3 kW, squares indicate the results when the plasma output was 4 kW, diamonds indicate the results when the plasma output was 7.2 kW, and triangles indicate the results of a comparative example (plasma output was 0 kW).

[0076] As shown in Fig. 9, the thickness of the zirconium oxide film is approximately the same regardless of the plasma output of 3 kW, 4 kW, or 7.2 kW, and it can be seen that the XRD peak intensity increases by reducing the plasma output. This result shows that the crystallinity of the zirconium oxide film increases by reducing the plasma output. In this way, by adjusting the plasma output, the crystallinity of the zirconium oxide film can be controlled without having much effect on the thickness of the zirconium oxide film.

[0077] 9, in the example, the XRD peak intensity is comparable to that of the comparative example, but with a thinner film thickness than that of the comparative example. This result shows that the zirconium oxide film can be thinned while maintaining its crystallinity by performing the crystallinity control step S5 after the oxidation step S4.

[0078] Fig. 10 is a diagram showing the crystal phase ratio of a zirconium oxide film, in which the bar graph on the left shows the results of a comparative example, the bar graph in the center shows the results when the plasma output was 3 kW, and the bar graph on the right shows the results when the plasma output was 7.2 kW.

[0079] As shown in Figure 10, by changing the plasma power from 3 kW to 7.2 kW, the ratio of tetragonal crystals decreases, and the ratios of orthorhombic crystals and monoclinic crystals increase. This result shows that the crystal phase ratio of the zirconium oxide film can be controlled by adjusting the plasma power.

[0080] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0081] In the above embodiment, the film forming apparatus is a semi-batch type apparatus, but the present disclosure is not limited thereto. For example, the film forming apparatus may be a single-wafer type apparatus that processes substrates one by one. For example, the film forming apparatus may be a batch type apparatus that processes multiple substrates at once. [Explanation of symbols]

[0082] S2 adsorption process S4 Oxidation process S5 Crystallinity control process S7 Judgment process W substrate

Claims

1. A method for forming a thin film on a substrate, comprising the steps of: (a) adsorbing a source gas onto a substrate; (b) supplying an oxidizing gas to the substrate to oxidize the source gas; (c) exposing the substrate to a plasma generated from a plasma gas including argon gas and oxygen gas; (d) repeating steps (a) to (c) in this order; having The step (c) includes controlling the crystallinity of the thin film formed on the substrate by adjusting a plasma output. Film formation method.

2. In the step (b), the source gas is oxidized by thermal oxidation. The film forming method according to claim 1 .

3. The plasma is generated by a remote plasma unit. The film forming method according to claim 1 .

4. The oxidizing gas is ozone gas. The film forming method according to claim 1 .

5. The thin film is a high-k film. The film forming method according to claim 1 .

6. The substrate is arranged along a circumferential direction on a rotating table provided in a vacuum chamber; within the vacuum chamber, provided above the turntable along a circumferential direction of the turntable are an adsorption region in which the step (a) is performed, an oxidation region in which the step (b) is performed, and a plasma region in which the step (c) is performed; the source gas is supplied to the adsorption region, the oxidation gas is supplied to the oxidation region, and the plasma gas is supplied to the plasma region, and the turntable is rotated in this state, thereby performing the step (d) on the substrate. The film forming method according to claim 1 .

7. A film forming apparatus for forming a thin film on a substrate, a vacuum vessel for accommodating the substrate; a gas supply unit that supplies a raw material gas, an oxidizing gas, and a plasma gas containing argon gas and oxygen gas into the vacuum chamber; a plasma unit for generating plasma from the plasma gas; A control unit; Equipped with The control unit is (a) adsorbing the source gas onto the substrate; (b) supplying the oxidizing gas to the substrate to oxidize the source gas; (c) exposing the substrate to a plasma generated from the plasma gas; (d) repeating steps (a) to (c) in this order; and controlling the gas supply and the plasma unit to perform the steps of: Film deposition equipment.

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