Plasma processing apparatus and plasma processing method

Abstract

To provide a technique capable of supplying ionized processing gas, a plasma, to a substrate to perform plasma processing on the substrate while suppressing deactivation of radicals in the ionized processing gas.SOLUTION: An apparatus for supplying ionized processing gas, a plasma, to a substrate in a processing vessel to perform plasma processing includes: a shower plate arranged between a plasma formation space that is arranged on the upper side of a mounting table provided in the processing vessel for mounting the substrate and constitutes a plasma formation mechanism for ionizing a processing gas to generate a plasma, and a substrate processing space, the shower plate including a plurality of processing gas supply holes passing the ionized processing gas toward the processing space; and a cover gas supply mechanism for supplying cover gas flowing so as to cover the side wall surfaces of the plurality of processing gas supply holes in the shower plate.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an apparatus for performing plasma processing and a method for performing plasma processing. [Background technology]

[0002] The CVD (Chemical Vapor Deposition) method and the ALD (Atomic Layer Deposition) method are known as methods for forming a film on a semiconductor wafer (hereinafter referred to as "wafer") in the manufacturing process of a semiconductor device. In these film forming processes, a source gas containing a film raw material is reacted with a reactive gas, which is a process gas that oxidizes or reduces the source gas, to deposit a substance that will become a film on the wafer.

[0003] In the film formation process, highly reactive active species obtained by converting reactive gas into plasma may be used. For example, Patent Document 1 describes a technology in which a high-frequency electric field is formed in the gas diffusion space between an upper electrode and a shower plate to generate a capacitively coupled plasma and dissociate the reactive gas. The dissociated reactive gas is supplied to a substrate on a stage through a plurality of gas discharge holes formed in the shower plate, and a film is formed. In addition to the film formation process, etching, modification, and other processes also use active species in plasma-converted gas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-203155 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a technique for performing plasma processing by supplying a processing gas that has been turned into plasma to a substrate while suppressing deactivation of radicals in the processing gas. [Means for solving the problem]

[0006] The present disclosure provides an apparatus for performing plasma processing by supplying a processing gas converted into plasma to a substrate in a processing vessel, a mounting table provided in the processing chamber for mounting the substrate thereon; a plasma generation space disposed above the mounting table and constituting a plasma generation mechanism for generating plasma from the processing gas; a processing gas supply unit for supplying the processing gas to the plasma generation space; a shower plate that is disposed between the plasma generation space and a processing space for the substrate in which the mounting table is provided, the shower plate having a plurality of processing gas supply holes formed therein through which the processing gas in the form of plasma flows from the plasma generation space toward the processing space; a cover gas supply mechanism for supplying a cover gas that flows so as to cover sidewall surfaces of the plurality of process gas supply holes. Effect of the Invention

[0007] According to the present disclosure, a plasma processing can be performed by supplying a processing gas to a substrate while suppressing deactivation of radicals in the plasma. [Brief description of the drawings]

[0008] [Figure 1] 1 is a vertical sectional side view of a film forming apparatus according to the present disclosure. [Diagram 2] FIG. 2 is an enlarged vertical cross-sectional side view of a plasma formation space of the film forming apparatus. [Diagram 3] FIG. 2 is an enlarged vertical sectional side view of the shower plate. [Figure 4] 1 is a perspective view of a shower plate according to a first embodiment, seen from above. FIG. [Diagram 5] 2 is a perspective view of the shower plate according to the first embodiment, as viewed from the bottom side. FIG. [Figure 6] 2 is an enlarged vertical sectional perspective view of the shower plate according to the first embodiment. FIG. [Figure 7]FIG. 11 is a perspective view of a shower plate according to a second embodiment, as viewed from above. [Figure 8] FIG. 11 is a perspective view of a shower plate according to a second embodiment, as viewed from below. [Figure 9] FIG. 11 is an enlarged vertical sectional perspective view of a shower plate according to a second embodiment. [Figure 10] FIG. 11 is an enlarged vertical sectional side view of a shower plate according to a third embodiment. [Figure 11] FIG. 1 is a vertical sectional side view of a film forming apparatus equipped with a plurality of shower plates. [Figure 12] 11 is a simulation result showing the distribution of the mass fraction of radicals in the process gas flowing through the reaction gas supply hole. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Film forming equipment> First, an example of the overall configuration of a film forming apparatus 1, which is one embodiment of the "apparatus for performing plasma processing" according to the present disclosure, will be described with reference to FIG. 1. The film forming apparatus 1 of this example is configured to supply a plasmatized reactive gas (processing gas) and a raw material gas containing a film raw material to a wafer W, and to form a film of a desired material on the surface of the wafer W. There is no particular limitation on the film formed on the wafer W, and the film may be a metal oxide film or a metal nitride film for forming an insulating film, or a metal film. As will be described later, the film forming apparatus 1 has a configuration capable of suppressing deactivation of radicals, which are active species, when supplying the plasmatized reactive gas in the plasma generation space 6 to the wafer W.

[0010] This film forming apparatus 1 is configured to supply a source gas containing a film source material such as a metal compound and a plasma-activated reactive gas into a processing vessel 11 that accommodates and processes a wafer W, and form a film of a desired material on the surface of the wafer W. The film forming method may be a CVD method in which the source gas and the plasma-activated reactive gas are continuously supplied to deposit a film material on the surface of the wafer W. Alternatively, it may be an ALD method in which the supply and exhaust of the source gas and the supply and exhaust of the plasma-activated reactive gas are alternately performed, and the adsorption of the source gas to the wafer W and the reaction with the reactive gas are repeated to form a thin film of the film material.

[0011] The processing vessel 11 of this embodiment is made of a flat cylindrical metal and is grounded. A loading / unloading port 12 for loading / unloading the wafer W and a gate valve 13 for opening / closing the loading / unloading port 12 are provided on the side wall of the processing vessel 11. An exhaust duct 14 having a circular shape in a plan view is provided above the loading / unloading port 12. A slit-shaped exhaust port 141 extending in the circumferential direction is formed on the inner peripheral surface of the exhaust duct 14. An opening 15 is formed on the side wall surface of the exhaust duct 14, and one end of an exhaust pipe 16 is connected through the opening 15. An exhaust mechanism 17 including a pressure adjustment mechanism and a vacuum pump is connected to the other end of the exhaust pipe 16.

[0012] A mounting table 31 for mounting a wafer W horizontally is provided in the processing vessel 11. A heater 311 for heating the wafer W is provided inside the mounting table 31. The upper end of a rod-shaped support member 34 that penetrates the bottom of the processing vessel 11 and extends in the vertical direction is connected to the center of the lower surface of the mounting table 31. A lifting mechanism 35 is connected to the lower end of the support member 34. The lifting mechanism 35 allows the mounting table 31 to move up and down between a lower position shown by a dashed line in FIG. 1 and an upper position shown by a solid line in the same figure. The lower position is a transfer position for transferring the wafer W between the wafer W and a transfer mechanism (not shown) for transferring the wafer W that enters the processing vessel 11 from the loading / unloading port 12. The upper position is a processing position where a film formation process is performed on the wafer W. In the processing position, the space above the mounting table 31 forms a processing space 10 for processing the wafer W.

[0013] Further, below the mounting table 31, there are disposed a plurality of support pins 38 that can be raised and lowered by a lifting mechanism 381. When the mounting table 31 is located at the transfer position, if the support pins 38 are raised and lowered, the support pins 38 protrude and retract from the upper surface of the mounting table 31 through through holes 39 provided in the mounting table 31. By this operation, the wafer W can be transferred between the mounting table 31 and the transfer mechanism.

[0014] <Gas supply system 4> A gas shower head 20 is provided inside the annular exhaust duct 14, i.e., above the mounting table 31, for supplying plasmatized reactive gas toward the processing space 10. A detailed configuration of the gas shower head 20 will be described in FIG. 2 and subsequent drawings. First, a configuration example of the gas supply system 4 that supplies various gases toward the gas shower head 20 will be described.

[0015] The gas supply system 4 in this example includes a raw material gas supply source 41 that supplies a raw material gas containing a precursor (film raw material) that is the raw material of the film material of the film formed on the wafer W, a reactive gas supply source 42 that supplies a reactive gas to react with the precursor to obtain the film material, and a cover gas supply source 43 that supplies a cover gas to suppress deactivation of the plasmatized reactive gas.

[0016] When forming a film containing a metal, such as titanium, as the film material, a source gas containing TiCl4 can be exemplified. Examples of the reactive gas include oxygen gas or ozone gas when forming an oxide film, ammonia gas when forming a nitride film, and hydrogen gas as a reducing gas when reducing a precursor to form a metal film. An auxiliary gas such as argon gas may be added to the reactive gas to assist in turning the reactive gas into plasma. Examples of the cover gas include inert gas such as nitrogen gas, argon gas, and helium gas.

[0017] One end of a raw material gas supply line 412 is connected to the raw material gas supply source 41, and a flow rate regulator 411 and a valve V1 are provided in this raw material gas supply line 412, in that order from the upstream side. One end of a reactive gas supply line 422 is connected to the reactive gas supply source 42, and a flow rate regulator 421 and a valve V2 are provided in this reactive gas supply line 422, in that order from the upstream side. In addition, when forming a film by ALD, for example, storage tanks 413 and 423 for each gas may be provided upstream of the valves V1 and V2 in order to supply a sufficient amount of raw material gas and reactive gas in a short time.

[0018] Furthermore, one end of a cover gas supply line 432 is connected to the cover gas supply source 43, and a flow rate regulator 431 and a valve V3 are provided in this cover gas supply line 432 in this order from the upstream side. The configuration of the gas supply system 4 is not limited to this example, and for example, a purge gas supply line for supplying a purge gas that promotes the discharge of source gases and reactive gases from the processing vessel 11 may be joined to each of the gas supply lines 412, 422, and 432. Examples of the purge gas include inert gases such as argon gas and nitrogen gas.

[0019] The other end of each of the gas supply lines 412, 422, 432 is connected to the gas showerhead 20. The specific connection positions with respect to the gas showerhead 20 will be described with reference to FIG. 2 and subsequent figures. A high frequency power supply 52 that applies high frequency power for generating plasma is connected to the gas shower head 20 via a matching box 51. A ground terminal is also connected to the high frequency power supply 52. ​​The connection positions of the high frequency power supply 52 and the ground terminal will also be described with reference to FIG. 2 and subsequent figures.

[0020] <Gas shower head 20> Next, a configuration example of a gas shower head 20 for generating plasma from a reactive gas and supplying it toward the processing space 10 will be described with reference to Fig. 2. The gas shower head 20 of this example is configured such that an electrode plate 61 and a shower plate 2 are arranged facing each other vertically with a ring-shaped side wall portion 62 made of a dielectric material therebetween. The electrode plate 61 and the shower plate 2 are configured, for example, in the shape of a metal disk. A high-frequency power supply 52 is connected to the electrode plate 61, and a ground terminal is connected to the shower plate 2, thereby forming a parallel plate type plasma generation mechanism.

[0021] In the above-mentioned plasma formation mechanism, the space between the electrode plate 61 and the shower plate 2, which are spaced apart from each other, constitutes a plasma formation space 6 for converting a reactive gas into plasma. In the film formation apparatus 1 of this embodiment, the reactive gas converted into plasma in the plasma formation space 6 is supplied to the processing space 10 (the wafer W on the mounting table 31) via the shower plate 2, which is arranged between the plasma formation space 6 and the processing space 10. From this perspective, the film formation apparatus 1 of this embodiment constitutes a remote-type plasma processing apparatus.

[0022] 2, for example, a reactive gas is supplied to the plasma generating space 6 from a reactive gas supply line 422 via an electrode plate 61. From this viewpoint, the reactive gas supply line 422 and the reactive gas supply source 42 connected to the upstream side thereof, the flow rate regulator 421, etc. configure the process gas supply unit of this example.

[0023] 1, 2, etc., a plurality of reactive gas supply holes (processing gas supply holes) 21 are formed in the shower plate 2. The reactive gas plasmatized in the plasma generation space 6 flows through these reactive gas supply holes 21 and is supplied to the processing space 10. On the other hand, when the active species of the reactive gas plasmatized contacts the side wall surface of the reactive gas supply hole 21 made of a grounded metal, there is a risk that the radicals, which are the active species that contribute to the reaction with the precursor, will be deactivated.

[0024] Therefore, the shower plate 2 of this embodiment is configured to supply a cover gas, for example an inert gas, so as to cover the side wall surface, thereby reducing the concentration of radicals contacting the side wall surface of the reaction gas supply hole 21 and suppressing deactivation of the radicals. The configuration and specific embodiments of the shower plate 2 will be described below with reference to Figs. 3 to 9. Note that since Fig. 1 is a drawing for explaining the overall configuration of the film forming apparatus 1, the configuration of the shower plate 2 is shown in a simplified manner.

[0025] As shown in Figures 2 and 3, the shower plate 2 is formed with a plurality of reactive gas supply holes 21 that penetrate the shower plate 2 in the vertical direction and serve as a flow path for the plasmatized reactive gas to flow from the plasma generation space 6 to the processing space 10.

[0026] The upper surface side of each reactive gas supply hole 21, i.e., the opening on the plasma generating space 6 side, is covered by a trap plate 23 made of a metal plate-shaped member. The trap plate 23 is formed with one or more gas introduction holes 231 whose total opening area is smaller than the opening area of ​​the reactive gas supply holes 21. The opening diameter of the gas introduction hole 231 can be, for example, 0.4 mm in the range of 0.1 to 1.0 mm.

[0027] By flowing the reactive gas from the plasma generation space 6 into the reactive gas supply hole 21 through the gas introduction hole 231 with a small opening area, some of the ions in the plasma P can be removed and supplied to the processing space 10. Since ions have high energy, they may cause roughness of the film formed on the wafer W or damage to the underlying surface. For this reason, it is preferable to supply the plasmatized reactive gas to the wafer W with a reduced ion content. Figures 3 and 4 to 6 show an example in which one gas introduction hole 231 is provided in each reactive gas supply hole 21, while Figures 7 to 9 and 10 show an example in which multiple gas introduction holes 231 are provided in each reactive gas supply hole 21.

[0028] The planar shape of the reactive gas supply hole 21 is not particularly limited, but each reactive gas supply hole 21a may be configured to have an elongated opening as shown in a first embodiment described later (FIGS. 5 and 6), or each reactive gas supply hole 21b may be configured to have a small hole shape as shown in a second embodiment (FIGS. 8 and 9). When the reactive gas supply hole 21a is configured with an elongated opening, the opening dimension in the short side direction as viewed from the mounting table 31 side can be, for example, 10 mm within a range of 10 to 15 mm. When the reactive gas supply hole 21b is configured as a circular small hole shape, the opening diameter as viewed from the mounting table 31 side can be, for example, 10 mm within a range of 10 to 15 mm.

[0029] All reactive gas supply holes 21 have in common that their side wall surfaces 211 are positioned around the flow of plasmatized reactive gas (indicated by solid arrows in FIG. 3) that passes through gas inlet hole 231 and heads toward processing space 10 (FIG. 3).

[0030] 3, sidewall surface 211 at the lower end of each reactive gas supply hole 21 is an area formed by tapered surface 211a in which the opening area of ​​reactive gas supply hole 21 gradually increases from the upstream side to the downstream side of the flow of reactive gas. By gradually increasing the opening area of ​​reactive gas supply hole 21, it is possible to supply plasmatized reactive gas toward a wider area of ​​wafer W on mounting table 31.

[0031] Furthermore, a cover gas supply hole 221 for supplying a cover gas is formed at a position on the upstream end side of the flow of the reaction gas in each reaction gas supply hole 21. The cover gas supplied from the cover gas supply hole 221 flows so as to cover the side wall surface 211. The cover gas supply hole 221 is configured as a slit formed at a position for supplying the cover gas along the inner circumferential surface of the side wall surface 211 constituting the reaction gas supply hole 21, or is configured as a plurality of small holes arranged in a row.

[0032] As shown in FIG. 2 and FIG. 3, a cover gas flow passage 22 through which a cover gas flows is formed in the shower plate 2. The cover gas flow passage 22 is connected to a cover gas supply hole 221 that supplies a cover gas to a side wall surface 211 of the reaction gas supply hole 21. On the other hand, the base end side of the cover gas flow passage 22 is connected to the above-mentioned cover gas supply line 432 via a cover gas flow passage 622 formed in a side wall portion 62 constituting the gas shower head 20, for example. A cover gas is supplied to the cover gas flow passage 22 from a cover gas supply source 43 via the cover gas supply line 432. The cover gas supply line 432 and the cover gas supply source 43 connected to the upstream side thereof, the flow rate regulator 431, and the like correspond to the cover gas supply unit of this example. The cover gas flow passage 22, the cover gas supply hole 221, and the above-mentioned cover gas supply unit constitute the cover gas supply mechanism of this example.

[0033] In addition to the above-mentioned components, a plurality of raw gas supply holes 24 are formed on the lower surface of the shower plate 2 to supply raw gas toward the processing space 10 (the wafer W on the mounting table 31). Each raw gas supply hole 24 is formed independently of the reactive gas supply hole 21 that supplies the plasmatized reactive gas. Each raw gas supply hole 24 is connected to a raw gas flow passage 241 formed inside the shower plate 2, for example. The raw gas flow passage 241 is formed separately from the cover gas flow passage 22 that supplies the cover gas, and the base end side of the raw gas flow passage 241 is connected to the above-mentioned raw gas supply line 412 via the raw gas flow passage 621 formed in the side wall portion 62. The raw gas is supplied to the raw gas flow passage 241 from the raw gas supply source 41 via the raw gas supply line 412.

[0034] It is not essential to supply cover gas to all supply holes (reactive gas supply hole 21, raw material gas supply hole 24) provided in the gas shower head 20. In this example, the raw material gas is directly supplied to the processing space 10 without being converted into plasma. As described above, the cover gas mechanism is provided to suppress deactivation of radicals in the plasma-converted gas. From this perspective, the cover gas supply mechanism of this example is not configured to supply cover gas to the side wall surface of the raw material gas supply hole 24 through which the raw material gas that is not converted into plasma flows.

[0035] Specific configuration examples of the shower plate 2 described above will be described with reference to two embodiments. <Shower plate 2a according to the first embodiment> In the shower plate 2a according to the first embodiment shown in Figures 4 to 6, each reactive gas supply hole 21a is configured to be an elongated opening. As shown in Figure 4, which is a perspective view of the shower plate 2a seen from the plasma generation space 6 side, and Figure 6, which is an enlarged vertical sectional perspective view, a plurality of slit-shaped gas introduction holes 231 are arranged in a row on the upper surface side of the shower plate 2a in correspondence with the positions at which the reactive gas supply holes 21a are formed.

[0036] 5 and 6, which are perspective views of the shower plate 2a viewed from the mounting table 31 side, a plurality of reaction gas supply holes 21a are arranged on the underside of the shower plate 2a in a direction intersecting with the long sides of the elongated openings. A slit-shaped cover gas supply hole 221 is formed at a position on the upstream end side of a side wall surface 211 along the long side direction of each reaction gas supply hole 21a. Furthermore, a slit-shaped source gas supply hole 24 is formed on the underside of the shower plate 2a so as to be sandwiched between two adjacent reaction gas supply holes 21a.

[0037] <Shower plate 2b according to second embodiment> In shower plate 2b according to the second embodiment shown in Figures 7 to 9, each reactive gas supply hole 21b is configured to be a small circular hole. As shown in Figure 7, which is a perspective view of shower plate 2b seen from the plasma generation space 6 side, and Figure 9, which is an enlarged vertical sectional view, gas introduction holes 231 having a smaller diameter than reactive gas supply holes 21b are formed on the upper surface side of shower plate 2b. A plurality of these gas introduction holes 231 are formed for each reactive gas supply hole 21b.

[0038] On the other hand, as shown in FIG. 8 and FIG. 9, which show the shower plate 2b viewed from the mounting table 31 side, the lower surface side of the shower plate 2b has a plurality of small reactive gas supply holes 21b arranged in a matrix and open. At the upstream end side of the side wall surface 211 of each reactive gas supply hole 21b, a slit-shaped cover gas supply hole 221 is formed along the entire inner circumferential surface. Also, as shown in FIG. 9, the cover gas flow passage 22 formed inside the shower plate 2b has a baffle plate 222 for adjusting the flow rate of the cover gas flowing into the cover gas supply hole 221 at a position surrounding the slit-shaped cover gas supply hole 221. Furthermore, on the lower surface side of the shower plate 2a, small hole-shaped raw material gas supply holes 24 are formed so as to be located between the reactive gas supply holes 21b arranged in a matrix.

[0039] <Control unit 100> Returning to the explanation of FIG. 1, the film forming apparatus 1 includes a control unit 100. The control unit 100 is configured with a computer including a storage unit, a memory, and a CPU that stores a program. The program includes commands (steps) for outputting control signals from the control unit 100 to each unit of the film forming apparatus 1 and for carrying in and out the wafer W and for executing film forming processes. The program is stored in a storage unit of the computer, such as a flexible disk, a compact disk, a hard disk, an MO (magneto-optical disk), a non-volatile memory, etc., and is read out from the storage unit and installed in the control unit 100.

[0040] <Film formation process> Next, an operation of performing a film formation process on a wafer W as a plasma process using the film formation apparatus 1 having the above-described configuration will be described. When the wafer W to be processed is transferred to the external vacuum transfer chamber, the gate valve 13 is opened, and a transfer mechanism (not shown) holding the wafer W is advanced into the processing vessel 11 through the load / unload port 12. Then, the wafer W is delivered to the mounting table 31 waiting at a lower position by using the support pins 38.

[0041] Thereafter, the transfer mechanism is removed from the processing chamber 11, the gate valve 13 is closed, and the pressure inside the processing chamber 11 and the temperature of the wafer W are adjusted. Next, a reactive gas is supplied to the plasma generating space 6, and high frequency power is applied from the high frequency power supply 52 to the electrode plate 61. As a result, the reactive gas supplied to the plasma generating space 6 is converted into plasma by capacitive coupling between the electrode plate 61 and the shower plate 2. As described above, an auxiliary gas such as argon gas may be supplied simultaneously to the reactive gas to be converted into plasma.

[0042] When the plasmatized reactive gas comes into contact with the upper surface of the trap plate 23 or passes through the gas inlet hole 231 provided in the trap plate 23, some of the ions are trapped and removed due to the sheath potential on the side wall surface of the gas inlet hole 231. On the upper surface of the trap plate 23 and the side wall surface of the gas inlet hole 231, some of the radicals are also deactivated and trapped, but most of them pass through the gas inlet hole 231 and flow into the reactive gas supply hole 21.

[0043] 3, the plasmatized reactive gas that has passed through the gas inlet hole 231 and flowed into the reactive gas supply hole 21 flows down through the reactive gas supply hole 21 and is supplied to the processing space 10. On the other hand, in the reactive gas supply hole 21, which has a longer flow path length than the gas inlet hole 231, there is a greater risk that radicals in the reactive gas that contribute to film formation will be deactivated due to contact with the side wall surface 211.

[0044] 3, in the shower plate 2 of this embodiment, a cover gas is supplied from the cover gas supply holes 221 so as to cover the side wall surface 211 as viewed from the flow of the reactive gas. This flow of the cover gas suppresses an increase in the concentration of radicals in the region near the side wall surface 211, and suppresses deactivation of radicals due to contact with the side wall surface 211. As a result, a reactive gas rich in radicals is supplied to the processing space 10. When the pressure in the processing vessel 11 is within a range of 0.133 to 1.33 kPa (1 to 10 torr) and the flow rate of the supply gas containing the plasmatized reactive gas in the reactive gas supply holes 21 is within a range of 1 to 10 m / sec, it is preferable to adjust the flow rate of the cover gas supplied from the cover gas supply holes 221 to be within a range of 1 to 50 m / sec. In addition, the raw material gas flowing out from the raw material gas supply hole 24 is also supplied to the processing space 10 .

[0045] At this time, when the film is formed by the CVD method, the supply of the plasmatized reactive gas through the reactive gas supply hole 21 and the supply of the raw material gas through the raw material gas supply hole 24 may be carried out in parallel. Furthermore, when forming a film by the ALD method, for example, a cycle of "supply of raw material gas via raw material gas supply hole 24 (adsorption of precursor onto wafer W) → supply of purge gas via reactive gas supply hole 21 and raw material gas supply hole 24 → supply of plasmatized reactive gas via reactive gas supply hole 21 (reaction with precursor adsorbed onto wafer W) → supply of purge gas via reactive gas supply hole 21 and raw material gas supply hole 24" is repeated a predetermined number of times.

[0046] After the film formation by the CVD method or the ALD method is performed for a preset period, the supply of the reactive gas and the cover gas of the raw material gas, and the supply of high frequency power to the electrode plate 61 are stopped. After that, the wafer W on which the film has been formed is unloaded from the processing vessel 11 in the reverse order to that of the loading.

[0047] <Effects> The film formation apparatus 1 according to this embodiment has the following advantages. A cover gas is supplied so as to flow to cover the side wall surface 211 of the reactive gas supply hole 21 through which the reactive gas plasma flows in the plasma formation space 6. As a result, an increase in the concentration of radicals on the surface of the side wall surface 211 is suppressed, and the reactive gas can be supplied to the wafer W to perform the film formation process while suppressing deactivation of radicals.

[0048] 10 shows an example in which the entire side wall surface 211 is configured with a tapered surface 211a from the upstream end side to the downstream end side of the flow of the reactive gas in the reactive gas supply hole 21. The cross-sectional area of ​​the reactive gas supply hole 21 increases in the flow direction of the reactive gas. Therefore, the side wall surface 211 is configured to be gradually farther away from the flow of the plasma-converted reactive gas, thereby more effectively reducing deactivation of radicals.

[0049] Here, the angle between the direction in which the cover gas is discharged from the cover gas supply hole 221 and the vertical direction is defined as α, and the angle between the tapered surface 211a, which is the side wall surface 211, and the vertical direction is defined as β. The relationship between the angles α and β may be "α>β" or "α≦β".

[0050] FIG. 11 shows the configuration of a gas shower head 20a having a plurality of shower plates, for example, two shower plates 2A and 2B, spaced apart from each other between the plasma generating space 6 and the processing space 10. The shower plates 2A and 2B arranged adjacent to each other vertically have a plurality of reactive gas supply holes 21 formed at positions offset from each other when viewed from the mounting table 31 side (positions that do not overlap when projected onto a plane parallel to the wafer W). With this configuration, the reactive gas that has been converted into plasma can be repeatedly collided with the trap plate 23 on the upper surface of the shower plates 2A and 2B and passed through the gas introduction holes 231 multiple times. As a result, more ions contained in the reactive gas can be removed. Meanwhile, the cover gas flows through the reactive gas supply holes 21 of each shower plate 2A and 2B so as to cover the side wall surface 211, so that deactivation of radicals is suppressed.

[0051] The plasma generating mechanism provided in the film forming apparatus 1 is not limited to a parallel plate type, and may generate plasma using microwaves. Also, ICP (Inductively Coupled Plasma) may be used, which generates eddy currents using a high-frequency fluctuating magnetic field formed around an antenna to convert the processing gas into plasma.

[0052] In addition, it is not essential to provide the trap plate 23 in the reactive gas supply hole 21, and the reactive gas supply hole 21 may be opened directly toward the plasma generation space 6. On the other hand, it is not essential to provide a region in which a tapered surface 211a is formed on the lower end side of the reactive gas supply hole 21. As shown in the shower plate 2B shown in FIG. 11, the reactive gas supply hole 21 may be configured such that the opening area does not change along with the flow of the reactive gas. Furthermore, it is not essential to form the cover gas flow passage 22 inside the shower plate 2. For example, a pipe may be provided along the upper surface of the shower plate 2 to supply a cover gas toward the side wall surface 211 of each reactive gas supply hole 21.

[0053] The position where the cover gas supply hole 221 is provided is not limited to the upstream end side of the flow of the plasmatized processing gas in the reactive gas supply hole 21. For example, in the elongated opening-shaped reactive gas supply hole 21a shown in FIG. 5, the cover gas supply hole 221 that supplies the cover gas laterally along the long side direction of the side wall surface 211 may be provided.

[0054] Furthermore, the cover gas supply hole 221 is not limited to a configuration in which the cover gas is supplied along the entire inner circumferential surface of the reactive gas supply hole 21. For example, in the elongated opening-shaped reactive gas supply hole 21a shown in Fig. 5, the cover gas supply hole 221 is provided in the side wall surface 211 on the long side, while the cover gas supply hole 221 is not provided in the side wall surface 211 on the short side. In addition, the cover gas is not limited to an inert gas, and for example, a reactive gas (processing gas) that has not been turned into plasma may be used.

[0055] The above-mentioned gas shower heads 20 and 20a are not limited to application to the film forming apparatus 1 that forms a film on the wafer W by reacting a raw material gas with a plasmatized reactive gas. For example, the gas shower heads may be applied to a film forming apparatus that forms a film by supplying a plasmatized raw material gas (processing gas) to the surface of the wafer W. In this case, the raw material gas is supplied to the plasma formation space 6, and the plasmatized raw material gas is supplied to the processing space 10 through the reactive gas supply hole (processing gas supply hole) 21 to which a cover gas is supplied. In this case, the shower plate 2 is not provided with raw material gas supply hole 24 or raw material gas flow path 241 independent from the reactive gas supply hole 21.

[0056] Furthermore, the gas showerhead 20, 20a having the above-described configuration may be provided to supply various gases into the processing vessel 11 of an etching processing apparatus that supplies an etching gas plasma to the wafer W to etch a film formed on the wafer W, or a modifying apparatus that performs a modification process that modifies a substance on the wafer W with a modifying gas plasma. In these cases, the etching gas and the modifying gas each correspond to the processing gas disclosed in the present disclosure.

[0057] 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. EXAMPLES

[0058] A fluid simulation was performed to determine the concentration distribution of radicals in reactive gas supply hole 21 when a cover gas is supplied from cover gas supply hole 221 so as to cover side wall surface 211 of reactive gas supply hole 21 through which plasma-converted reactive gas flows.

[0059] A. Simulation Conditions Under a pressure condition of 1.33 kPa (10 torr), a reactive gas containing radicals with a mass fraction of 0.1 was supplied from the plasma generating space 6 side to the reactive gas supply hole 21 at a flow rate of 5 m / sec. The diameter of the reactive gas supply hole 21 was 10 mm, and the flow path length was 15 mm (flow rate 0.248 slm / min). The mass fraction distribution of radicals contained in the fluid in the reactive gas supply hole 21 was simulated under the condition that a cover gas with a radical mass fraction of 0 was supplied to the reactive gas supply hole 21 from the cover gas supply hole 221 with an opening width of 1 mm at a flow rate of 20 m / sec (flow rate 0.191 slm / min).

[0060] B. Simulation Results The simulation results are shown in Fig. 12. According to the results shown in Fig. 12, the mass fraction of radicals is in the range of about 0.07-0.1 in the central region of the reactive gas supply hole 21, and the mass fraction distribution of radicals is maintained close to that at the time of supply to the reactive gas supply hole 21. On the other hand, the mass fraction distribution of radicals in the vicinity of the side wall surface 211 covered by the flow of the cover gas is suppressed to a low concentration range of about 0-0.05. Therefore, it can be said that the supply of the cover gas flowing to cover the side wall surface 211 contributes to a reduction in the radical concentration in the vicinity of the side wall surface 211, and can effectively suppress deactivation of radicals due to contact with the side wall surface 211. [Explanation of symbols]

[0061] 1 Film deposition equipment 11 Processing vessel 20, 20a Shower plate 21, 21a, 21b Reactive gas supply hole 211 Side wall 221 Cover gas supply hole 31 Placement table 6 Plasma formation space

Claims

1. An apparatus for performing plasma processing by supplying a processing gas converted into plasma to a substrate in a processing chamber, comprising: a mounting table provided in the processing chamber for mounting the substrate thereon; a plasma generation space disposed above the mounting table and constituting a plasma generation mechanism for generating plasma from the processing gas; a processing gas supply unit for supplying the processing gas to the plasma generation space; a shower plate that is disposed between the plasma generation space and a processing space for the substrate in which the mounting table is provided, the shower plate having a plurality of processing gas supply holes formed therein through which the processing gas in the form of plasma flows from the plasma generation space toward the processing space; a cover gas supply mechanism for supplying a cover gas that flows so as to cover sidewall surfaces of the plurality of process gas supply holes.

2. 2. The apparatus of claim 1, wherein the cover gas supply mechanism comprises: a cover gas flow path formed in the shower plate and provided with a cover gas supply hole that supplies the cover gas to a side wall surface of the process gas supply hole; and a cover gas supply unit that supplies the cover gas to the cover gas flow path.

3. 3. The apparatus according to claim 2, wherein the cover gas supply hole is opened at a position where the cover gas is supplied from an upstream end side of a flow of the plasma-converted processing gas in the processing gas supply hole.

4. The apparatus according to claim 2 , wherein the cover gas supply hole is open at a position where the cover gas is supplied along the entire inner circumferential surface of the side wall of the process gas supply hole.

5. 2. The apparatus according to claim 1, wherein the processing gas supply hole is provided with a trap plate that covers an opening on the plasma formation space side and causes the plasmatized processing gas to collide with the trap plate, and the trap plate is provided with one or more gas introduction holes whose total opening area is smaller than the opening area of ​​the processing gas supply hole.

6. 2. The apparatus according to claim 1, wherein the side wall surface of the processing gas supply hole includes a region formed of a tapered surface whose opening area gradually increases from the upstream side to the downstream side of the flow of the plasma-converted processing gas.

7. 2 . The apparatus according to claim 1 , wherein the processing gas supply holes are arranged as a plurality of elongated openings facing the processing space when viewed from the mounting table side.

8. 2. The apparatus according to claim 1, wherein the process gas supply hole is formed so that a plurality of small holes are arranged in a matrix when viewed from the mounting table side.

9. the plasma generating space is formed between the shower plate made of metal and an electrode plate disposed between the shower plate and the electrode plate with a gap therebetween, with a dielectric therebetween; 2. The apparatus according to claim 1, wherein the plasma generation mechanism comprises a high frequency power supply connected to one side of the electrode plate and the shower plate, and a grounded terminal connected to the other side, and generates plasma from the processing gas supplied to the plasma generation space by capacitive coupling between the electrode plate and the shower plate.

10. 2. The apparatus of claim 1, wherein the shower plate has, in addition to the plurality of process gas supply holes, a plurality of raw material gas supply holes for supplying a raw material gas toward the processing space to react with the plasmatized process gas to form a film on the substrate, and the cover gas supply mechanism does not supply the cover gas to the raw material gas supply holes.

11. 2. The apparatus according to claim 1, wherein a plurality of said shower plates are provided between said plasma generation space and said processing space with spaces therebetween.

12. 12. The apparatus according to claim 11, wherein each of the shower plates arranged adjacent to each other has a plurality of the process gas supply holes formed at positions shifted from each other when viewed from the mounting table side.

13. The apparatus of claim 1 , wherein the cover gas is an inert gas.

14. The apparatus of claim 1 , wherein the process gas is a non-plasma process gas.

15. A method for performing plasma processing by supplying a processing gas converted into plasma to a substrate in a processing vessel, comprising the steps of: a mounting table provided in the processing chamber for mounting the substrate thereon; a plasma generation space provided above the mounting table and constituting a plasma generation mechanism for generating plasma from the processing gas; and a shower plate provided between the plasma generation space and a processing space for the substrate in which the mounting table is provided, the shower plate having a plurality of processing gas supply holes formed therein through which the plasma-generated processing gas flows from the plasma generation space toward the processing space, supplying the processing gas into the plasma generation space; a step of generating plasma from the processing gas supplied to the plasma generation space by the plasma generation mechanism; supplying the processing gas in plasma form from the plasma generation space to the substrate on the stage in the processing space through the plurality of processing gas supply holes of the shower plate; supplying the process gas, flowing a cover gas so as to cover sidewall surfaces of the plurality of process gas supply holes.

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