Plasma source and plasma processing device

Abstract

To provide a plasma source that facilitates plasma ignition.SOLUTION: There is provided a plasma source comprising: a first chamber configured to form a flat first plasma generation space, and having a first wall and a second wall that have the largest area among a plurality of walls constituting the first chamber and face each other; a gas supply configured to supply gas into the first chamber; an electromagnetic wave supply having a dielectric window that is provided in an opening provided in the first wall to face the first plasma generation space, and configured to supply an electromagnetic wave through the dielectric window into the first chamber; a plasma supply configured to supply radicals contained in plasma that is generated from the gas supplied into the first chamber by the electromagnetic wave to an outside of the first chamber; and a plasma ignition source provided in the first chamber to protrude from an inner wall of the second wall facing the dielectric window and to be separated from the dielectric window.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to plasma sources and plasma processing apparatus. [Background technology]

[0002] It is important to use plasma to form films in order to obtain high-quality films at low temperatures. In recent years, there has been progress in thinning films, and plasma ALD (Atomic Layer Deposition) film formation has been adopted. While the use of plasma allows high-quality thin films to be obtained at low temperatures, electrical and physical damage to the film can be an issue. To solve this problem, film formation using the ALD method using a remote source has been proposed.

[0003] For example, Patent Documents 1 and 2 disclose the configuration of a remote plasma processing apparatus having an ICP (Inductively Coupled Plasma) type remote plasma source. When an ICP type remote source is used as the remote source in this way, the stable range of plasma is narrow, and plasma ignition may not be easy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-150023 A [Patent Document 2] JP 2014-49529 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a plasma source that facilitates plasma ignition. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a plasma source including: a first chamber configured to form a flat first plasma generation space, the first chamber having the largest area among a plurality of walls constituting the first chamber and having opposing first and second walls; a gas supply unit configured to supply a gas into the first chamber; an electromagnetic wave supply unit having a dielectric window provided in an opening provided in the first wall facing the first plasma generation space and configured to supply an electromagnetic wave into the first chamber through the dielectric window; a plasma supply unit that supplies radicals contained in plasma generated from the gas supplied into the first chamber by the electromagnetic wave to the outside of the first chamber; and a plasma ignition source protruding from an inner wall of the second wall facing the dielectric window in the first chamber and spaced apart from the dielectric window. Effect of the Invention

[0007] According to one aspect, a plasma source that facilitates plasma ignition can be provided. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional perspective view showing a plasma processing apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a plasma source according to the first embodiment. [Diagram 3] FIG. 2 is an enlarged view of a portion of the plasma source according to the first embodiment. [Figure 4] FIG. 2 is a diagram showing a plasma ignition source according to an embodiment. [Diagram 5] 1 is a graph showing an example of a relationship between a plasma potential and a floating potential. [Figure 6] FIG. 11 is a schematic cross-sectional view showing a plasma processing apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0010] First Embodiment [Plasma processing equipment] First, a plasma processing apparatus 2 according to a first embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a cross-sectional perspective view showing the plasma processing apparatus 2 according to the first embodiment. Fig. 2 is a view showing a plasma source 1 (remote plasma source) according to the first embodiment. Fig. 3 is an enlarged view of a part of the plasma source 1 according to the first embodiment.

[0011] The plasma processing apparatus 2 shown in FIG. 1 has a plasma source 1. The plasma source 1 generates plasma from a gas by the electric field of electromagnetic waves. The electromagnetic waves include microwaves. The microwaves have a frequency band of 300 MHz to 3 THz. The electromagnetic waves may include VHF waves having a frequency band of 150 MHz to 300 MHz. Radicals in the generated plasma are supplied into the third plasma generation space 30e of the plasma processing apparatus 2 and used for processing a substrate. The radicals transferred from the plasma source 1 are dissociated again by high-frequency power applied to the plasma processing apparatus 2 and used for processing a substrate.

[0012] The plasma processing apparatus 2 includes a third chamber 10. The third chamber 10 defines a third plasma generation space 30e in which a substrate is processed. The substrate W is processed in the third plasma generation space 30e. The third chamber 10 has an axis AX as its center line. The axis AX extends in the vertical direction.

[0013] In the embodiment, the third chamber 10 includes a chamber body 12. The chamber body 12 has a generally cylindrical shape and is open at the top. The chamber body 12 provides the sidewall and bottom of the third chamber 10. The chamber body 12 is made of a metal such as aluminum. The chamber body 12 is grounded.

[0014] The sidewall of the chamber body 12 provides a passage 12p. The substrate W passes through the passage 12p when being transferred between the inside and the outside of the third chamber 10. The passage 12p can be opened and closed by a gate valve 12v. The gate valve 12v is provided along the sidewall of the chamber body 12.

[0015] The third chamber 10 further includes an upper wall 14. The upper wall 14 is made of a metal such as aluminum. The upper wall 14 closes an upper opening of the chamber body 12. The upper wall 14 and the chamber body 12 are grounded.

[0016] The bottom of the third chamber 10 provides an exhaust port 16a. The exhaust port 16a is connected to an exhaust system 16. The exhaust system 16 includes a pressure controller, such as an automatic pressure control valve, and a vacuum pump, such as a turbomolecular pump.

[0017] The plasma processing apparatus 2 further includes a mounting table 18. The mounting table 18 is provided in the third chamber 10. The mounting table 18 is configured to support a substrate W mounted thereon. The substrate W is mounted on the mounting table 18 in a substantially horizontal state. The mounting table 18 may be supported by a support member 19. The support member 19 extends upward from the bottom of the third chamber 10. The mounting table 18 and the support member 19 may be formed of a dielectric material such as aluminum nitride.

[0018] The plasma processing apparatus 2 further includes a showerhead 20. The showerhead 20 is made of a metal such as aluminum. The showerhead 20 has a substantially disk shape and a hollow structure. The showerhead 20 shares an axis line AX as its central axis line. The showerhead 20 is provided above the mounting table 18 and below the upper wall 14. The showerhead 20 constitutes a ceiling portion that defines the internal space of the third chamber 10.

[0019] The shower head 20 further provides a diffusion chamber 30d therein. The shower head 20 provides a plurality of gas holes 20i penetrating the shower head 20 in the thickness direction from the lower part of the diffusion chamber 30d. The plurality of gas holes 20i open to the lower surface of the shower head 20, and the shower head 20 forms a gas path for introducing gas from the diffusion chamber 30d through the plurality of gas holes 20i into the third plasma generation space 30e. As a result, the gas is introduced toward the third plasma generation space 30e between the shower head 20 and the mounting table 18 in the third chamber 10. The mounting table 18 functions as a lower electrode, and the shower head 20 functions as an upper electrode.

[0020] The periphery of the showerhead 20 is covered with a dielectric member 33 such as aluminum oxide. The periphery of the mounting table 18 is covered with a dielectric member 34 such as aluminum oxide. If no high frequency is applied to the showerhead 20, the dielectric member 33 does not have to be provided. However, it is preferable to provide the dielectric member 33 in order to define the area of ​​the showerhead 20 that functions as a counter electrode for the mounting table 18. It is also preferable to provide the dielectric member 33 in order to make the ratio of anodes and cathodes of the electrodes as equal as possible.

[0021] A high frequency power supply 60 is connected to the mounting table 18 via a matching device 61. The matching device 61 has an impedance matching circuit. The impedance matching circuit is configured to match the impedance of the load of the high frequency power supply 60 to the output impedance of the high frequency power supply 60. The frequency of the high frequency supplied from the high frequency power supply 60 is lower than the frequencies of VHF waves and microwaves supplied to the plasma source 1 described below, and is a frequency of 60 MHz or less. The frequency of the high frequency may be 13.56 MHz. The high frequency power supply 60 may be supplied to the shower head 20.

[0022] The plasma processing apparatus 2 has a plasma source 1 on the upper wall 14. FIG. 1 shows a cross-sectional perspective view of the inside of the third chamber 10 and a cross-sectional perspective view of the plasma source 1. The plasma source 1 has a plasma supply unit 23 that supplies plasma, and the plasma supply unit 23 is fixed to the upper wall 14. The plasma supply unit 23 is a hollow member having a substantially cylindrical shape made of a metal such as aluminum, and is structured to supply active species such as radicals and gas. The plasma supply unit 23 shares an axis AX as its central axis. The lower end of the plasma supply unit 23 communicates with an opening formed in the center of the upper wall 14 of the third chamber 10.

[0023] The first chamber 22 is a flat rectangular waveguide centered on the axis AX. The upper end of the plasma supply unit 23 extends in the width direction of the flat first chamber 22 and is connected to the lower end of the first chamber 22. The first chamber 22 is configured to form a flat first plasma generation space 22d therein. The first chamber 22 and the plasma supply unit 23 are made of a conductor such as aluminum and have a ground potential. Furthermore, the plasma source 1 has an electromagnetic wave supply unit 36 ​​connected to the first wall 22a of the first chamber 22 (see FIG. 2).

[0024] 1 and 2, the first chamber 22 has the largest area among the multiple walls constituting the first chamber 22, and has a first wall 22a and a second wall 22b that face each other. Two electromagnetic wave supplying units 36 are arranged in the first wall 22a in the longitudinal direction (vertical direction) of the first chamber 22, side by side in the vertical direction with the axis AX as the center. The two electromagnetic wave supplying units 36 have the same configuration.

[0025] The electromagnetic wave supplying unit 36 ​​has a dielectric window 38 provided in an opening 22e (see Figs. 1 and 3) provided in the first wall 22a facing the first plasma generation space 22d, and is configured to supply electromagnetic waves into the first chamber 22 through the dielectric window 38. As the electromagnetic waves, VHF waves or microwaves having a frequency of 150 MHz or more are supplied. In this embodiment, microwaves are propagated from a microwave oscillator 40 (see Fig. 2) through an input port to the electromagnetic wave supplying unit 36. The electromagnetic wave supplying unit 36 ​​has a coaxial waveguide structure and has an approximately cylindrical inner conductor 36a and an approximately cylindrical outer conductor 36b arranged concentrically around the inner conductor 36a. The microwaves propagate between the inner conductor 36a and the outer conductor 36b, pass through the approximately disk-shaped quartz member 37, and propagate to the dielectric window 38 through a slot S of the antenna 26 provided in a gap U (see Fig. 3) between the quartz member 37 and the dielectric window 38. Note that a space may be provided between the inner conductor 36a and the outer conductor 36b, or alumina (Al2O3) or the like may be disposed between them. The microwaves pass through the dielectric window 38 and are radiated into the first chamber 22 from the opening 22e in the first wall 22a of the first chamber 22. Note that the inner conductor 36a, the quartz member 37, and the dielectric window 38 are covered with the outer conductor 36b.

[0026] Fig. 3(a) shows the AA cross section of Fig. 2, and is a plan view of the vicinity of the opening 22e of the first wall 22a from the inner wall side of the first wall 22a, and Fig. 3(b) shows the BB cross section passing through the center of the opening 22e shown in Fig. 3(a). As shown in Fig. 3(a), the conductor antenna 26 is in contact with the surface opposite to the surface of the dielectric window 38 exposed from the opening 22e, and a donut-shaped slot S is formed.

[0027] 3(b), the surface of the dielectric window 38 exposed from the opening 22e is recessed in a circular shape at a central region 38a of the dielectric window 38, and the central region 38a is thinner than an outer peripheral region 38b of the dielectric window 38. This can improve the plasma ignition characteristics.

[0028] Returning to FIG. 1, the plasma source 1 further includes a gas supply unit 22c and a plasma ignition source 24. The gas supply unit 22c is connected to a gas supply source 50 and supplies gas supplied from the gas supply source 50 into the first chamber 22. The gas supply unit 22c is configured to supply gas into the first chamber 22. As shown in FIG. 2, the gas supply unit 22c is provided on the third wall 22f, which has the smallest area among the multiple walls constituting the first chamber 22. The gas supply unit 22c is provided at the center of the third wall 22f and above the dielectric window 38 of the electromagnetic wave supply unit 36. Two electromagnetic wave supply units 36 are provided in the direction of gas flow (vertical direction) flowing downward from the gas supply unit 22c in the first chamber 22. Thereby, the gas supplied from the gas supply unit 22c can be decomposed by an electric field formed near the opening 22e by the microwaves supplied from the electromagnetic wave supply unit 36 ​​when the gas flows downward, and plasma can be efficiently generated. In this embodiment, two electromagnetic wave supply units 36 are arranged in the gas flow direction (vertical direction) on the first wall 22a, but three or more may be arranged, or only one may be arranged. The more electromagnetic wave supply units 36 are arranged, the higher the radical generation efficiency and plasma generation efficiency. An electromagnetic wave supply unit 36 ​​may also be provided on the second wall 22b side.

[0029] The plasma supply unit 23 supplies radicals contained in the plasma generated from the gas supplied into the first chamber 22 by the microwaves supplied to the first plasma generation space 22d to the outside of the first chamber 22. In this embodiment, the outside of the first chamber 22 is the third chamber 10. The radicals contained in the plasma are activated species of the gas. The electromagnetic wave supply units 36 are arranged vertically along the axis AX, which is the center line of the flat first chamber 22. The gas supply unit 22c is provided on the third wall 22f, which is perpendicular to the first wall 22a and the second wall 22b, among the multiple walls constituting the first chamber 22. The third wall 22f is the wall with the smallest area among the multiple walls constituting the first chamber 22. Furthermore, the gas supply unit 22c is formed on the third wall 22f, which is above the first wall 22a to which the electromagnetic wave supply unit 36 ​​is attached.

[0030] As a result, the plasma density becomes highest near the center of the flat first chamber 22 due to the microwaves supplied through the dielectric window 38 of the electromagnetic wave supply unit 36. In addition, gas and radicals flow through the center of the flat first chamber 22 from top to bottom while diffusing.

[0031] The plasma supply unit 23 is provided at a position facing the third wall 22f of the first chamber 22. With this configuration, the vicinity of the upper electromagnetic wave supply unit 36 ​​among the electromagnetic wave supply units 36 arranged in the vertical direction, which is the direction of gas flow, becomes a first dissociation area where dissociation of gas is promoted. Also, the vicinity of the lower electromagnetic wave supply unit 36 ​​becomes a second dissociation area where dissociation of gas is promoted. Since the gas dissociated in the first dissociation area is further dissociated in the second dissociation area, the degree of dissociation of gas increases vertically downward in the first plasma generation space 22d in the first chamber 22. Therefore, high-density plasma is generated in the first chamber 22. As a result, the plasma supply unit 23 can supply sufficient radicals to the third chamber 10.

[0032] In this way, radicals are supplied from the plasma source 1 to the third plasma generation space 30e between the lower electrode (mounting table 18) and the upper electrode (shower head 20), and the substrate W placed on the lower electrode is processed. At this time, radicals flow from the plasma source 1 through the shower head 20 via a plurality of gas holes 20i provided in the shower head 20, and are supplied to the third plasma generation space 30e. The radicals supplied to the third plasma generation space 30e may recombine during transport to form gas. The radicals and the recombined gas are decomposed by the high-frequency power of the high-frequency power source 60, and the plasma thus generated performs processing such as film formation on the substrate W. By supplying radicals from the plasma source 1, sufficient dissociation can be achieved even if the high-frequency power supplied from the high-frequency power source 60 is small and the frequency is relatively low. This allows film formation on the substrate with little damage. Although not shown, gas that can be sufficiently dissociated only by the high-frequency power source 60 may be supplied directly to the shower head 20 without passing through the plasma source 1.

[0033] The control unit (control device) 90 may be a computer having a processor 91 and a memory 92. The control unit 90 includes an arithmetic unit, a storage unit, an input device, a display device, a signal input / output interface, and the like. The control unit 90 controls each part of the plasma processing device 2 including the plasma source 1. In the control unit 90, an operator can use the input device to input commands and the like to manage the plasma processing device 2. In addition, the control unit 90 can visualize and display the operating status of the plasma processing device 2 using the display device. Furthermore, the memory 92 of the control unit 90 stores a control program and recipe data. The control program is executed by the processor 91 of the control unit 90 to execute various processes in the plasma processing device 2. The processor 91 executes the control program and controls each part of the plasma processing device 2 according to the recipe data, whereby various processes, for example, a plasma processing method, are executed in the plasma processing device 2.

[0034] With the above-described configuration, the plasma processing apparatus 2 according to this embodiment can supply sufficient radicals to the third chamber 10 using the plasma source 1 that generates plasma by electromagnetic waves of a relatively high frequency to activate gas. This makes it possible to execute a process that causes less damage to the substrate W by using a remote plasma source that uses microwaves.

[0035] Furthermore, the plasma source 1 according to this embodiment has a plasma ignition source 24. The plasma ignition source 24 protrudes from the inner wall of the second wall 22b facing the dielectric window 38 in the first chamber 22 and is provided at a distance from the dielectric window 38.

[0036] Here, the ignition of plasma by the plasma ignition source 24 will be described. In the case of plasma ignition using microwaves like the plasma source 1, the discharge electric field E bd The ignition performance is determined by the above.

[0037]

number

[0038] On the other hand, in a parallel plate type plasma processing apparatus such as the third chamber 10, a discharge voltage V V is generated between the lower electrode and the upper electrode by high frequency power according to Paschen's law, as shown in formula (2). bd The ignition performance is determined by the above.

[0039]

number

[0040] In formula (1), D and K are coefficients determined by the type of gas, p is the pressure in the chamber, and f is the frequency of the electromagnetic waves. m is a constant (approximately 0.5) determined by the type of gas. In formula (2), A and B are coefficients determined by the type of gas, p is the pressure in the chamber, d is the distance between the lower electrode and the upper electrode, and γ se is the secondary electron emission coefficient. The secondary electron emission coefficient is determined by the materials and surface conditions of the lower and upper electrodes.

[0041] In other words, Paschen's law does not hold for plasma ignition in the plasma source 1. Therefore, in the plasma source 1, the discharge voltage V bd In the plasma source 1, the discharge electric field E shown in equation (1) is not determined by bd Therefore, the plasma ignition source 24 of the plasma source 1 has a shape and arrangement that is easy to ignite, which is specific to microwaves and VHF waves of 150 MHz or more, and makes it easy to ignite plasma in the first chamber 22.

[0042] Specifically, the plasma ignition source 24 protrudes from the inner wall of the second wall 22b facing the dielectric window 38 in the first chamber 22 and is provided at a distance from the dielectric window 38. When no plasma is generated in the first chamber 22, microwaves are radiated into the flat first chamber 22, and the radiated microwaves are reflected by the rod-shaped conductor of the plasma ignition source 24 protruding from the opposing surface, and the microwaves (reflected waves) return to the inner wall side of the first wall 22a. Then, a standing wave is generated between the incident wave of the microwave output from the dielectric window 38 and the reflected wave reflected by the plasma ignition source 24. Since the first chamber 22 is flat and the gap between the first wall 22a and the second wall 22b is narrow, a high electric field is generated in the first chamber 22, making it easy to ignite the plasma. On the other hand, after plasma ignition, the electric field between the plasma ignition source 24 and the inner wall of the first wall 22a does not become high.

[0043] The plasma ignition source 24 has a conductive rod-shaped member, and has, for example, a mushroom-shaped tip (the cross section of the tip is approximately trapezoidal). The entirety or tip of the plasma ignition source 24 may be covered with an insulator. The rod-shaped member of the plasma ignition source 24 may be installed in three patterns, for example, as shown in Figs. 4(a) to (c).

[0044] 4(a), the plasma ignition source 24 has a conductive rod-shaped member 24b (including a tip portion 24a), the surface of which is coated with an insulating member 24c such as ceramics. The internal rod-shaped member 24b has the same potential as the first chamber 22, and is at ground potential.

[0045] In FIG. 4(b), an insulating member 24d is sandwiched between the inner wall of the second wall 22b, which is the opposing wall of the first wall 22a, and the rod-shaped member 24b (including the tip portion 24a), so that the rod-shaped member 24b itself is at a floating potential.

[0046] In FIG. 4(c), a rod-shaped member 24b (including a tip portion 24a) itself is made of an insulating material such as ceramics, and an electrode 24e that functions as a passive ignition source is disposed inside the rod-shaped member 24b.

[0047] The plasma ignition source 24 is a passive ignition source, and no voltage is applied to it. The plasma ignition source 24 needs to have an electrode (conductor) for reflecting microwaves. Therefore, the plasma ignition source 24 is not limited to the form shown in FIG. 4(a) to FIG. 4(c), and may have an electrode (conductor) for functioning as a passive ignition source provided near the dielectric window 38. The conductor part of the rod-shaped member of the plasma ignition source 24 may be at ground potential or floating potential, but a floating potential is more preferable than a ground potential. Even if the conductor part of the rod-shaped member of the plasma ignition source 24 is at ground potential, it functions as a passive ignition source. However, considering contamination, particles, and damage, it is preferable that the rod-shaped member (electrode, conductor part) of the plasma ignition source 24 is at floating potential. The reason for this will be described with reference to FIG. 5.

[0048] FIG. 5 is a graph showing an example of the relationship between plasma potential and floating potential. The horizontal axis Z of the graph in FIG. 5 indicates the distance (Z) from the surface of the dielectric window 38 to the tip of the electrode (conductor) of the plasma ignition source 24, and the vertical axis indicates the plasma potential and the floating potential. Line P is the plasma potential according to the distance (Z), and line f is the floating potential according to the distance (Z). Line f shows the case where the plasma ignition source 24 is configured to have a floating potential. In this experiment, the pressure in the first chamber 22 was controlled to 0.5 Torr (67 Pa), and Ar gas was supplied into the first chamber 22 to generate plasma of Ar gas.

[0049] According to this, when the rod-shaped member of the plasma ignition source 24 is at ground potential, the plasma potential itself becomes the incident potential that indicates the force when ions are incident on the rod-shaped member. As a result, when Z is about 10 mm, a voltage of about 17 eV is applied to the rod-shaped member. In contrast, when the rod-shaped member is at floating potential, when Z is about 10 mm, a voltage of about 10 eV is applied to the rod-shaped member, and the voltage applied to the rod-shaped member can be reduced by the potential difference between the plasma potential of line P and the floating potential of line f. If the rod-shaped member is coated with ceramics, a voltage of about 10 eV causes almost no damage to the surface of the plasma ignition source 24.

[0050] From the above, it is sufficient that the tip of the plasma ignition source 24 and the bottom surface of the dielectric window 38 are separated by about 3 mm to 10 mm in the horizontal direction (direction perpendicular to the axis AX). However, it is more preferable to separate the tip of the plasma ignition source 24 and the bottom surface of the dielectric window 38 by about 5 mm to 10 mm, since this can further suppress contamination, particles, and damage.

[0051] The plasma ignition source 24 can shorten the time to turn on the plasma. The reason for this is as follows. In a normal matching box, first, the matching position in the matching box is adjusted to the plasma ignition position. After the plasma is ignited, the matching position is mechanically moved to the next matching position (the matching position after the plasma is ignited). This mechanical movement of the matching position takes time.

[0052] In contrast, the plasma source 1 is configured to be set in advance to the matching position after plasma ignition. Normally, plasma is not ignited at the matching position after plasma ignition, but the plasma source 1 is configured to easily ignite plasma even at the matching position after plasma ignition by providing the plasma ignition source 24. Therefore, it is not necessary to move the matching position after plasma ignition.

[0053] Therefore, the plasma ignition source 24 does not need to move the alignment position, and the time to turn on the plasma can be shortened. This allows the gas to be replaced and plasma to be ignited quickly, making it more suitable for the ALD (atomic layer deposition) process and increasing productivity. However, it can also be applied to film formation by the CVD (Chemical Vapor Deposition) method.

[0054] The distance between the inner walls of the first wall 22a and the second wall 22b is 10 to 100 times the skin depth of the plasma. The reason why the distance is in the range of 10 to 100 times is that the plasma conductivity shown below varies greatly with the plasma density. In the present embodiment, the distance between the inner walls of the first wall 22a and the second wall 22b is about 20 mm (see FIG. 1).

[0055] The value of the skin depth varies depending on (1) frequency, (2) electron density, and (3) the collision frequency of electrons and neutral particles. Here, the collision frequency of electrons and neutral particles (3) is determined by the gas species and electron temperature. The skin depth δ is calculated using formula (3). Skin depth δ = [2 / (ωμ0σ dc )] 1 / 2 (3) Here, ω is the power frequency, μ0 is the magnetic permeability of a vacuum, and σ dc is the plasma conductivity. The plasma conductivity is calculated by equation (4). Plasma conductivity σ dc =e 2 n e / (mν m ) · · · (4) where e is the elementary charge, n e is the electron density, m is the mass of the electron, ν m is the electron-neutral collision frequency.

[0056] When the distance between the inner walls of the first wall 22a and the second wall 22b is 10 times the skin depth, the distance is about 20 mm when the microwave frequency is 800 MHz, about 28 mm when it is 400 MHz, and about 12 mm when it is 2.45 GHz. This makes it possible to realize a plasma source 1 with a low plasma electron temperature and high electron density. The pressure inside the first chamber 22 is used at 0.5 Torr or more.

[0057] According to the plasma source 1 described above, the thickness of the first chamber 22 is reduced, and the electromagnetic wave supply units 36 are arranged in the gas flow direction, thereby improving the gas decomposition efficiency and the radical generation efficiency. In addition, by arranging the plasma ignition source 24 corresponding to the electromagnetic wave supply unit 36, it is possible to provide a plasma source 1 that can stably and easily ignite plasma based on the above-mentioned ignition principle specific to microwaves. In addition, the plasma ignition source 24 can shorten the plasma on time. This can improve productivity, especially in the ALD process. In the ALD process, for example, in the case of forming a SiN film, a raw material gas such as silane gas (SiH4) is supplied from the gas supply source 50, and then a reducing gas such as nitrogen gas (N2) is supplied, and this is repeated. In the CVD process, for example, silane gas (SiH4) and nitrogen gas (N2) are supplied from the gas supply source 50. In the case of cleaning, a cleaning gas such as NF3 gas is supplied from the gas supply source 50.

[0058] <Second embodiment> [Plasma processing equipment] Next, a plasma processing apparatus 2 according to a second embodiment will be described with reference to Fig. 6. Fig. 6 is a cross-sectional perspective view showing the plasma processing apparatus 2 according to the second embodiment. Since the configuration of the third chamber 10 of the plasma processing apparatus 2 according to the second embodiment is the same as that of the first embodiment, the description will be omitted and only the plasma source 1B according to the second embodiment will be described.

[0059] The plasma source 1B according to the second embodiment has components such as the first chamber 22 and the electromagnetic wave supply unit 36 ​​of the plasma source 1 according to the first embodiment, as well as components such as a second chamber 28 and an electromagnetic wave supply unit 136 at an opposing position. The components such as the first chamber 22 and the electromagnetic wave supply unit 36 ​​included in the plasma source 1B according to the second embodiment are the same as those of the plasma source 1 according to the first embodiment, and therefore will not be described.

[0060] The second chamber 28 has the same shape as the first chamber 22 and is configured to form a flat second plasma generation space 28d. The second chamber 28 has a fourth wall 28a adjacent to the second wall 22b of the first chamber 22 and a fifth wall 28b facing the fourth wall 28a.

[0061] The gas supply unit 22c is provided in the center of the upper wall of the second chamber 28, above the dielectric window 138 of the electromagnetic wave supply unit 136, similarly to the first chamber 22. The gas supply unit 22c supplies a gas different from the gas supplied into the first chamber 22, into the second chamber 28. For example, the gas supply unit 22c may alternately supply silane gas and N2 gas into the first chamber 22, and supply a cleaning gas into the second chamber 28.

[0062] The electromagnetic wave supply unit 136 has the same configuration as the electromagnetic wave supply unit 36, and has an inner conductor 136a and an outer conductor 136b. The electromagnetic wave supply unit 136 is provided at the same height as the electromagnetic wave supply unit 36, facing the electromagnetic wave supply unit 36. However, this is not limited, and the electromagnetic wave supply unit 136 may be provided at a different height from the electromagnetic wave supply unit 36, facing the electromagnetic wave supply unit 36. In this case, one of the electromagnetic wave supply units 136 is disposed between the electromagnetic wave supply units 36. Two electromagnetic wave supply units 136 are provided in the direction of gas flow (vertical direction) that flows downward from the gas supply unit 22c inside the second chamber 28.

[0063] The electromagnetic wave supply unit 136 has a dielectric window 138 provided in an opening (not shown) in the fifth wall 28b facing the second plasma generation space 28d, and is configured to supply microwaves into the second chamber 28 through the dielectric window 138.

[0064] The gas supplied into the second chamber 28 is decomposed by microwaves in the second plasma generation space 28d to generate plasma. The plasma supply unit 23 supplies radicals contained in the plasma to the third chamber 10 outside the second chamber 28. For example, the plasma supply unit 23 supplies radicals contained in the plasma of the silane gas and reducing gas (e.g., N2 gas) generated in the first plasma generation space 22d to the third chamber 10. Also, the plasma supply unit 23 supplies radicals contained in the plasma of the cleaning gas (e.g., NF3 gas) generated in the second plasma generation space 28d to the third chamber 10.

[0065] 6, a plasma ignition source (not shown) disposed in the second plasma generation space 28d protrudes from the inner wall of the fourth wall 28a on the opposite side of the dielectric window 138 in the second chamber 28 and is provided at a distance from the dielectric window 138. The configuration of the plasma ignition source 24 may be any of those shown in FIG.

[0066] Furthermore, the plasma source 1B according to the second embodiment has an on-off gas valve 22h that controls the supply (on) and stop (off) of different radicals (gas), namely, the radicals (gas) supplied from the first chamber 22 to the third chamber 10 and the radicals (gas) supplied from the second chamber 28 to the third chamber 10.

[0067] When supplying two different types of radicals (gases), it is preferable to excite them separately in different chambers before supplying them to the third chamber 10. For example, if a process gas such as N2 gas or silane gas is flowed in the same chamber as the chamber in which NF3 gas is flowed, the accuracy of the process performed on the substrate may be reduced due to the influence of fluorine remaining in the chamber due to NF3 gas. Therefore, the plasma source 1B of this embodiment has two chambers, and different gases are separately supplied to each chamber. The plasma source 1B has a plate-shaped opening and closing gas valve 22h near the outlets of the first chamber 22 and the second chamber 28. The opening and closing gas valve 22h opens and closes between the first plasma processing space 22d (reducing gas excitation part) and the third plasma processing space 30e (substrate processing space) in the first chamber 22. The opening and closing gas valve 22h also opens and closes between the second plasma processing space 22d (cleaning gas excitation part) and the third plasma processing space 30e (substrate processing space) in the second chamber 28. The on-off gas valve 22h may be in the form of a gate valve, which is slidably moved to control opening and closing. The source gas (reactive gas) such as silane gas may be supplied directly to the third chamber .

[0068] In the plasma source 1B according to the second embodiment, the gas decomposition efficiency and radical generation efficiency can be improved by reducing the thickness of the first chamber 22 and the second chamber 28. In addition, plasma ignition can be facilitated. In addition, the two types of gases are not mixed, and the opening and closing gas valve 22h is further provided to prevent the excited species of different gases from being mixed into each of the chambers 22 and 28. This can eliminate the influence on the substrate processing process caused by flowing different gas species into the same chamber. In addition, by providing the electromagnetic wave supply units 36, 136 on both sides of the first chamber 22 and the second chamber 28, the number of the electromagnetic wave supply units 36, 136 can be increased to further increase the radical generation efficiency.

[0069] The plasma ignition source 24 can be configured to detect the state of the plasma as an insulated probe. In this way, the signal obtained from the insulated probe can be analyzed by a computer connected to the plasma ignition source 24, thereby monitoring the electron density and electron temperature in the first chamber 22 and the second chamber 28 and analyzing the state of the plasma.

[0070] In this case, measurement windows may be opened in the first chamber 22 and the second chamber 28, and a plasma measurement monitor (such as an OES (Optical Emission Spectrometer), an insulating probe, etc.) may be attached to detect the state of the plasma.

[0071] The plasma processing apparatus 2 according to each embodiment described above has plasma sources 1 and 1B that function as remote plasma that converts gas into plasma by the electric field of microwaves or VHF waves, improves the gas decomposition efficiency and radical generation efficiency, and transfers the generated radicals (active species of gas) to the third chamber 10. By transferring the radicals generated in the plasma sources 1 and 1B to the third chamber 10, it is possible to convert the radicals into plasma in the third chamber 10 with less power, and film formation can be performed by the ALD method with less damage.

[0072] The plasma source and plasma processing apparatus according to the embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The matters described in the above embodiments can be configured in other ways without any contradiction, and can be combined without any contradiction.

[0073] It should be noted that the plasma source 1 and the plasma source 1B do not necessarily have to include the plasma ignition source 24 in the first chamber 22 and / or the second chamber . In this case, the plasma source 1 and / or the plasma source 1B are provided, which include a first chamber 22 configured to form a flat first plasma generation space 22d, the first chamber 22 having the largest area among the multiple walls constituting the first chamber 22 and opposing first and second walls 22a and 22b, a gas supply unit 22c configured to supply gas into the first chamber 22, an electromagnetic wave supply unit 36 ​​having a dielectric window 38 provided in an opening provided in the first wall 22a facing the first plasma generation space 22d and configured to supply electromagnetic waves into the first chamber 22 through the dielectric window 38, and a plasma supply unit 23 that supplies radicals contained in the plasma generated from the gas supplied into the first chamber 22 by the electromagnetic waves to the outside of the first chamber 22, and the electromagnetic wave supply unit 36 ​​is provided in a plurality of units in the direction of the flow of gas flowing through the first plasma generation space 22d from the gas supply unit 22c to the outside of the first chamber 22. [Explanation of symbols]

[0074] 1. 1B Plasma source 2. Plasma processing equipment 10. Third Chamber 20. Shower Head 22 First Chamber 22c Gas supply section 22d First plasma generation space 23 Plasma supply unit 24 Plasma Ignition Source 28 Second Chamber 28d Second plasma generation space 30e Third Plasma Generation Space 36, 136 Electromagnetic wave supply section 38, 138 Dielectric window 90 Control section 91 Processor 92 Memory

Claims

1. A first chamber configured to form a flat first plasma generation space, the first chamber having a largest area among a plurality of walls constituting the first chamber and having a first wall and a second wall opposed to each other; a gas supply configured to supply a gas into the first chamber; an electromagnetic wave supply unit having a dielectric window provided in an opening provided in the first wall facing the first plasma generation space, and configured to supply an electromagnetic wave into the first chamber through the dielectric window; a plasma supply unit that supplies radicals contained in plasma generated from the gas supplied into the first chamber by the electromagnetic waves to the outside of the first chamber; a plasma ignition source protruding from an inner wall of the second wall facing the dielectric window in the first chamber and spaced apart from the dielectric window; The plasma source has

2. A first chamber configured to form a flat first plasma generation space, the first chamber having a largest area among a plurality of walls constituting the first chamber and having a first wall and a second wall opposed to each other; a gas supply configured to supply a gas into the first chamber; an electromagnetic wave supply unit having a dielectric window provided in an opening provided in the first wall facing the first plasma generation space, and configured to supply an electromagnetic wave into the first chamber through the dielectric window; a plasma supply unit that supplies radicals contained in plasma generated from the gas supplied into the first chamber by the electromagnetic waves to the outside of the first chamber, A plasma source, the electromagnetic wave supply unit being installed in a plurality of units in a direction of gas flow flowing through the first plasma generation space from the gas supply unit to the plasma supply unit.

3. A second chamber configured to form a flat second plasma generation space, the second chamber having a fourth wall adjacent to the second wall and a fifth wall facing the fourth wall, the gas supply unit supplies a gas different from the gas supplied into the first chamber into the second chamber; the electromagnetic wave supplying unit further has a dielectric window provided in an opening provided in the fifth wall facing the second plasma generation space, and is configured to supply an electromagnetic wave into the second chamber through the dielectric window; the plasma supply unit further supplies radicals contained in the plasma generated from the gas supplied into the second chamber in the second plasma generation space by the electromagnetic waves to the outside of the second chamber; The plasma ignition source is further provided in the second chamber, protruding from an inner wall of the fourth wall facing the dielectric window and spaced apart from the dielectric window.

10. The plasma source of claim 1.

4. the gas supply unit supplies a reducing gas to one of the first chamber or the second chamber, and supplies a cleaning gas to the other of the first chamber or the second chamber; The plasma source of claim 3.

5. Further, an opening / closing valve is provided for each of the first chamber and the second chamber, and controls supply and stop of the radicals of the reducing gas and the cleaning gas to be supplied to the plasma supply unit. A plasma source according to claim 3 or 4.

6. The plasma ignition source has a conductive rod-shaped member, a surface of the rod-shaped member is coated with an insulating member, and the rod-shaped member is at a ground potential. A plasma source according to any one of claims 1, 3 to 5.

7. The plasma ignition source has a conductive rod-shaped member, an insulating member is sandwiched between the rod-shaped member and an inner wall of the second wall, and the rod-shaped member is at a floating potential. A plasma source according to any one of claims 1, 3 to 5.

8. The plasma ignition source has a conductive rod-shaped member, an insulating member is sandwiched between the rod-shaped member and an inner wall of the fourth wall, and the rod-shaped member is at a floating potential. A plasma source according to any one of claims 3 to 5.

9. The plasma ignition source is an insulating rod-shaped member, and an electrode is provided inside the rod-shaped member. A plasma source according to any one of claims 1, 3 to 5.

10. The plasma ignition source is configured to detect a state of the plasma as an insulated probe. A plasma source according to any one of claims 1, 3 to 9.

11. The electromagnetic wave supply unit supplies VHF waves or microwaves having a frequency band of 150 MHz or more as the electromagnetic waves. A plasma source according to any one of the preceding claims.

12. The gas supply unit is provided on a third wall perpendicular to the first wall and the second wall among a plurality of walls constituting the first chamber. A plasma source according to any one of the preceding claims.

13. The gas supply unit is provided in a third wall having a smallest area among a plurality of walls constituting the first chamber. A plasma source according to any one of the preceding claims.

14. The plasma supply unit is provided at a position facing the third wall of the first chamber.

14. A plasma source according to claim 12 or 13.

15. A central region of the dielectric window is thinner than a peripheral region of the dielectric window. A plasma source according to any one of the preceding claims.

16. The distance between the inner walls of the first wall and the second wall is 10 to 100 times the skin depth; A plasma source according to any one of the preceding claims.

17. 1. A plasma processing apparatus having a plasma source and a third chamber connected to the plasma source, the third chamber has a third plasma generation space for processing a substrate; The plasma source comprises: A first chamber configured to form a flat first plasma generation space, the first chamber having a largest area among a plurality of walls constituting the first chamber and having a first wall and a second wall opposed to each other; a gas supply configured to supply a gas into the first chamber; an electromagnetic wave supply unit having a dielectric window provided in an opening provided in the first wall facing the first plasma generation space, and configured to supply an electromagnetic wave into the first chamber through the dielectric window; a plasma supply unit that supplies radicals contained in plasma generated from the gas supplied into the first chamber by the electromagnetic waves to the outside of the first chamber; a plasma ignition source protruding from an inner wall of the second wall facing the dielectric window in the first chamber and spaced apart from the dielectric window.

18. 1. A plasma processing apparatus having a plasma source and a third chamber connected to the plasma source, the third chamber has a third plasma generation space for processing a substrate; The plasma source comprises: A first chamber configured to form a flat first plasma generation space, the first chamber having a largest area among a plurality of walls constituting the first chamber and having a first wall and a second wall opposed to each other; a gas supply configured to supply a gas into the first chamber; an electromagnetic wave supply unit having a dielectric window provided in an opening provided in the first wall facing the first plasma generation space, and configured to supply an electromagnetic wave into the first chamber through the dielectric window; a plasma supply unit that supplies radicals contained in plasma generated from the gas supplied into the first chamber by the electromagnetic waves to the outside of the first chamber, The plasma processing apparatus, wherein a plurality of the electromagnetic wave supply units are installed in a direction of a gas flow flowing through the first plasma generating space from the gas supply unit to the plasma supply unit.

19. a radio frequency supply unit that supplies radio frequency waves to a lower electrode on which a substrate is placed in the third chamber or to an upper electrode facing the lower electrode; supplying the radicals from the plasma source to a third plasma generation space between the lower electrode and the upper electrode to process a substrate placed on the lower electrode; The plasma processing apparatus according to claim 17 or 18.

20. the upper electrode functions as a shower head having a plurality of gas holes; supplying the radicals from the plasma source to the third plasma generation space through the plurality of gas holes provided in the shower head; The plasma processing apparatus according to claim 19.

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