Substrate processing apparatus, substrate processing method, semiconductor device manufacturing method and program

Abstract

The in-plane uniformity of substrate processing can be improved.　A substrate processing apparatus has a processing container in which a processing gas is plasma-excited, a gas supply system configured to supply the processing gas into the processing container, and a plasma-generating structure comprising at least two coils that are spirally wound around the outer circumference of the processing container and are each supplied with a high-frequency power, wherein the at least two coils have substantially the same diameter and substantially the same length and are configured so that the value where the amplitudes of the standing waves generated by the coils overlap is smaller than the peak amplitude value of the standing wave.

Description

[Technical Field]

[0001] The present disclosure relates to a substrate processing apparatus. 、 Substrate processing method 、 Semiconductor device manufacturing method and programs Regarding. [Background technology]

[0002] BACKGROUND ART As one step in the manufacturing process of a semiconductor device, substrate processing is sometimes performed by supplying high frequency power to a coil to excite a processing gas into plasma (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 183401 Brochure [Patent Document 2] International Publication No. 2019 / 053806 Brochure [Patent Document 3] Japanese Patent Application Publication No. 2020-53419 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the plasma density becomes high near the ground position on the coil, which may reduce the in-plane uniformity of the substrate processing.

[0005] An object of the present disclosure is to provide a technique capable of improving the in-plane uniformity of substrate processing. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a processing vessel in which a processing gas is plasma-excited; a gas supply system configured to supply the process gas into the process vessel; a plasma generation structure including at least two coils wound spirally around the outer periphery of the processing vessel and each coil is supplied with high-frequency power; At least two of the coils have approximately the same diameter and approximately the same length, and are configured so that the combined amplitude of the standing waves generated by each coil is smaller than the peak amplitude of the standing waves. Technology is provided. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to improve the in-plane uniformity of substrate processing. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a substrate processing apparatus suitably used in one aspect of the present disclosure. [Figure 2] FIG. 1 is a diagram illustrating a principle of plasma generation according to one embodiment of the present disclosure. [Figure 3] FIG. 2 is a diagram illustrating a double coil preferably used in one embodiment of the present disclosure. [Figure 4] Fig. 4(A) is a diagram showing the power supply position and the ground position in the circumferential direction of each of the two coils constituting the double coil shown in Fig. 3. Fig. 4(B) is a diagram showing standing waves of high-frequency current in each of the two coils constituting the double coil shown in Fig. 3. [Figure 5] FIG. 1 is a schematic configuration diagram of a controller of a substrate processing apparatus suitably used in one embodiment of the present disclosure, showing a control system of the controller in a block diagram. [Figure 6] FIG. 1 is a flow chart showing a substrate processing process suitably used in one embodiment of the present disclosure. [Figure 7] Fig. 7(A) is a diagram showing the power supply position and the ground position in the circumferential direction of each of the two coils constituting the double coil according to the modified example. Fig. 7(B) is a diagram showing standing waves of high-frequency current in each of the two coils constituting the double coil shown in Fig. 7(A). [Figure 8]10 is a diagram showing the power supply position and the ground position in the circumferential direction of each of the two coils that make up the double coil according to the modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] <One aspect of the present disclosure> Hereinafter, one embodiment of the present disclosure will be described with reference to Figures 1 to 6. Note that the drawings used in the following description are all schematic, and the dimensional relationships between elements, the ratios of elements, etc. shown in the drawings do not necessarily match those in reality. Furthermore, the dimensional relationships between elements, the ratios of elements, etc. do not necessarily match between multiple drawings.

[0010] (1) Configuration of the substrate processing equipment A substrate processing apparatus 100 according to one embodiment of the present disclosure will be described below with reference to Fig. 1. The substrate processing apparatus according to one embodiment of the present disclosure is configured to perform substrate processing using plasma mainly on a film or base formed on a substrate surface.

[0011] (Processing chamber) The substrate processing apparatus 100 includes a processing furnace 202 for plasma processing wafers 200 serving as substrates. The processing furnace 202 includes a processing vessel 203 constituting a processing chamber 201. The processing vessel 203 forms a plasma generation space 201a in which a processing gas is plasma-excited. The processing vessel 203 includes a dome-shaped upper vessel 210 serving as a first vessel, and a bowl-shaped lower vessel 211 serving as a second vessel. The upper vessel 210 is placed over the lower vessel 211 to form the processing chamber 201. The upper vessel 210 is made of quartz.

[0012] A gate valve 244 is provided on the lower sidewall of the lower vessel 211. When the gate valve 244 is open, the wafer 200 can be loaded into the processing chamber 201 or unloaded from the processing chamber 201 via a loading / unloading port 245 using a transfer mechanism. When the gate valve 244 is closed, the gate valve 244 functions as a sluice valve that maintains the airtightness of the processing chamber 201.

[0013] The processing chamber 201 has a plasma generation space 201a, which is surrounded by a double coil 212 serving as an electrode, and a substrate processing space 201b, which is connected to the plasma generation space 201a and serves as a substrate processing chamber where the wafer 200 is processed. The plasma generation space 201a is a space where plasma is generated, and refers to the space within the processing chamber 201 that is above and below the lower end of the double coil 212. On the other hand, the substrate processing space 201b is a space where the wafer 200 is processed using plasma, and refers to the space below the lower end of the double coil 212. In one embodiment of the present disclosure, the plasma generation space 201a and the substrate processing space 201b are configured to have approximately the same horizontal diameter. The double coil 212 will be described in detail below.

[0014] (susceptor) A susceptor 217 serving as a substrate mounting table for mounting a wafer 200 is disposed at the center of the bottom side of the processing chamber 201. The susceptor 217 is provided below the double coil 212 within the processing chamber 201.

[0015] A heater 217b serving as a heating mechanism is integrally embedded inside the susceptor 217. The heater 217b is configured to heat the wafer 200 when power is supplied thereto.

[0016] The susceptor 217 is electrically insulated from the lower chamber 211. The impedance adjustment electrode 217c is provided inside the susceptor 217 in order to further improve the uniformity of the density of the plasma generated on the wafer 200 placed on the susceptor 217, and is grounded via an impedance variable mechanism 275 serving as an impedance adjustment unit.

[0017] The susceptor 217 is provided with a susceptor lifting mechanism 268 that includes a drive mechanism for lifting and lowering the susceptor 217. Furthermore, the susceptor 217 is provided with a through-hole 217a, and wafer push-up pins 266 are provided on the bottom surface of the lower vessel 211. When the susceptor 217 is lowered by the susceptor lifting mechanism 268, the wafer push-up pins 266 are configured to pass through the through-holes 217a without coming into contact with the susceptor 217.

[0018] (Gas supply section) A gas supply head 236 is provided above the processing chamber 201, i.e., on top of the upper vessel 210. The gas supply head 236 includes a cap-shaped lid 233, a gas inlet 234, a buffer chamber 237, an opening 238, a shielding plate 240, and a gas outlet 239, and is configured to supply processing gas into the processing chamber 201. The buffer chamber 237 functions as a dispersion space that disperses the processing gas introduced from the gas inlet 234.

[0019] The downstream end of an oxygen-containing gas supply pipe 232a that supplies an oxygen-containing gas as a processing gas, the downstream end of a hydrogen-containing gas supply pipe 232b that supplies a hydrogen-containing gas as a processing gas, and an inert gas supply pipe 232c that supplies an inert gas as a processing gas are connected to the gas inlet 234 so that they converge. The oxygen-containing gas supply pipe 232a is provided, in order from the upstream side, with an oxygen-containing gas supply source 250a, a mass flow controller (MFC) 252a as a flow rate control device, and a valve 253a as an open / close valve. The hydrogen-containing gas supply pipe 232b is provided, in order from the upstream side, with a hydrogen-containing gas supply source 250b, an MFC 252b, and a valve 253b. The inert gas supply pipe 232c is provided, in order from the upstream side, with an inert gas supply source 250c, an MFC 252c, and a valve 253c. A valve 243a is provided downstream of the junction of the oxygen-containing gas supply pipe 232a, the hydrogen-containing gas supply pipe 232b, and the inert gas supply pipe 232c, and is connected to the upstream end of the gas inlet 234. By opening and closing the valves 253a, 253b, 253c, and 243a, processing gases such as an oxygen-containing gas, a hydrogen-containing gas, and an inert gas can be supplied into the processing chamber 201 through the gas supply pipes 232a, 232b, and 232c while adjusting the flow rate of each gas using the MFCs 252a, 252b, and 252c.

[0020] A gas supply unit (gas supply system) according to one embodiment of the present disclosure mainly includes the gas supply head 236, the oxygen-containing gas supply pipe 232a, the hydrogen-containing gas supply pipe 232b, the inert gas supply pipe 232c, the MFCs 252a, 252b, and 252c, and the valves 253a, 253b, 253c, and 243a. That is, the gas supply unit (gas supply system) is configured to supply a processing gas into the processing vessel 203.

[0021] The gas supply head 236, the oxygen-containing gas supply pipe 232a, the MFC 252a, and the valves 253a and 243a constitute an oxygen-containing gas supply system according to one embodiment of the present disclosure. The gas supply head 236, the hydrogen-containing gas supply pipe 232b, the MFC 252b, and the valves 253b and 243a constitute a hydrogen-containing gas supply system according to one embodiment of the present disclosure. The gas supply head 236, the inert gas supply pipe 232c, the MFC 252c, and the valves 253c and 243a constitute an inert gas supply system according to one embodiment of the present disclosure.

[0022] (Exhaust section) A gas exhaust port 235 for exhausting processing gas from the processing chamber 201 is provided on a sidewall of the lower vessel 211. The upstream end of a gas exhaust pipe 231 is connected to the gas exhaust port 235. The gas exhaust pipe 231 is provided with, in this order from the upstream side, an APC (Auto Pressure Controller) valve 242 serving as a pressure regulator (pressure adjustment unit), a valve 243b serving as an on-off valve, and a vacuum pump 246 serving as a vacuum exhaust device. The gas exhaust port 235, the gas exhaust pipe 231, the APC valve 242, and the valve 243b mainly constitute an exhaust unit according to one embodiment of the present disclosure. The vacuum pump 246 may be included in the exhaust unit.

[0023] (Plasma generation unit) A double coil 212 is provided on the outer periphery of the processing chamber 201, i.e., on the outside of the sidewall of the upper vessel 210, so as to be wound spirally multiple times along the outer periphery of the upper vessel 210. The double coil 212 is composed of a first coil 212a and a second coil 212b.

[0024] Connected to first coil 212a are RF sensor 272, high frequency power supply 273, and matching box 274 that matches the impedance and output frequency of high frequency power supply 273. Connected to second coil 212b are RF sensor 282, high frequency power supply 283, and matching box 284 that matches the impedance and output frequency of high frequency power supply 283.

[0025] The high-frequency power supplies 273 and 283 supply high-frequency power (RF power) to the first coil 212a and the second coil 212b, respectively. The RF sensors 272 and 282 are provided on the output sides of the high-frequency power supplies 273 and 283, respectively, and monitor information on the forward waves and reflected waves of the supplied high-frequency power. The reflected wave information monitored by the RF sensors 272 and 282 is input to the matching devices 274 and 284 and the high-frequency power supplies 273 and 283, respectively, and the variable capacitors in the matching devices 274 and 284 and the output frequencies of the high-frequency power supplies 273 and 283 are controlled based on the respective reflected wave information so as to minimize the amplitude of the reflected wave. In other words, this control matches the input impedance of the matching device 274, the input impedance of the matching device 284, and the output impedance of the high-frequency power supplies 273 and 283, respectively.

[0026] Each of the high-frequency power supplies 273 and 283 includes a power supply control means (control circuit) including a high-frequency oscillation circuit and a preamplifier for defining the oscillation frequency and output, and an amplifier (output circuit) for amplifying the output to a predetermined output. The power supply control means controls the amplifier based on output conditions related to frequency and power preset via an operation panel. The amplifier supplies a constant high-frequency power to each of the first coil 212a and the second coil 212b via a transmission line.

[0027] High frequency power supply 273, matching box 274, and RF sensor 272 are collectively referred to as high frequency power supply unit 271. Note that any one of high frequency power supply 273, matching box 274, and RF sensor 272, or a combination thereof, may be referred to as high frequency power supply unit 271. High frequency power supply unit 271 is also referred to as a first high frequency power supply unit.

[0028] Moreover, high frequency power supply 283, matching box 284, and RF sensor 282 are collectively referred to as high frequency power supply unit 281. Note that any one of high frequency power supply 283, matching box 284, and RF sensor 282, or a combination thereof, may be referred to as high frequency power supply unit 281. High frequency power supply unit 281 is also referred to as a second high frequency power supply unit. First high frequency power supply unit 271 and second high frequency power supply unit 281 are collectively referred to as a high frequency power supply unit.

[0029] Shielding plate 223 is provided to shield the electric field outside double coil 212 and to form a capacitance component (C component) required to form a resonant circuit between first coil 212a or second coil 212b. Shielding plate 223 is generally made of a conductive material such as an aluminum alloy and has a cylindrical shape. Shielding plate 223 is disposed approximately 5 to 150 mm away from the outer periphery of double coil 212.

[0030] A first plasma generation unit is mainly constituted by the first coil 212a and the high frequency power supply unit 271. A second plasma generation unit is mainly constituted by the second coil 212b and the high frequency power supply unit 281. The first plasma generation unit and the second plasma generation unit are collectively referred to as the plasma generation unit.

[0031] Next, the plasma generation principle and the properties of the generated plasma will be described with reference to Fig. 2. The plasma generation principle for the first coil 212a and the second coil 212b is the same, so the first coil 212a will be used as an example for the description.

[0032] The equivalent circuit formed by the first coil 212a and the generated plasma can be represented by an RLC parallel circuit, and plasma generation efficiency is maximized during resonance. When the wavelength of the high-frequency wave supplied from the high-frequency power supply 273 is the same as the length of the first coil 212a, the resonance condition of the parallel circuit is that the reactance component represented by the inductive component L and the capacitive component C is zero, that is, the impedance of the parallel circuit is pure resistance. However, because the inductive component L and the capacitive component C vary significantly depending on the plasma generation state, a control mechanism is required to adjust them to satisfy the resonance condition.

[0033] Therefore, in this embodiment, the above control mechanism has a function of detecting the reflected wave from the first coil 212a when plasma is generated by the RF sensor 272, and controlling the matching box 274 and the high-frequency power supply 273 based on the detected reflected wave information.

[0034] Specifically, the frequency control circuit of the high frequency power supply 273 increases or decreases the output frequency so as to minimize the amplitude of the reflected wave based on reflected wave information from the first coil 212a when plasma is generated and detected by the RF sensor 272. The variable capacitor control circuit of the matching box 274 increases or decreases the capacitance. Note that the high frequency power supply 273 and the RF sensor 272, or the matching box 274 and the RF sensor 272, may be configured as one unit.

[0035] With this configuration, as shown in FIG. 2, in the first coil 212a of this embodiment, high-frequency power is supplied at the actual resonant frequency of the coil containing the plasma (or high-frequency power is supplied so as to match the actual impedance of the coil containing the plasma), forming a standing wave with a phase difference of nearly 90° between the high-frequency voltage and the high-frequency current. When the length of the first coil 212a is the same as the wavelength of the high-frequency wave, the largest high-frequency current is generated at the electrical midpoint of the first coil 212a (the node where the high-frequency voltage is zero). Therefore, near the electrical midpoint, there is almost no capacitive coupling with the plasma, and a doughnut-shaped plasma is formed due to inductive coupling.

[0036] Furthermore, based on the same principle, a doughnut-shaped plasma is also formed by inductive coupling at the end position of the spiral of first coil 212a, near the ground position.

[0037] In a double coil configuration, a doughnut-shaped plasma is formed by inductive coupling near the grounding point, as well as at the electrical midpoint of each coil, resulting in the highest plasma density. Therefore, when the grounding points of the two coils are adjacent to each other, the standing waves of the high-frequency currents from both coils overlap, resulting in a localized increase in maximum amplitude. This locally high plasma density leads to poor substrate processing uniformity and accelerated deterioration of quartz components, which require more frequent maintenance and result in longer equipment downtime.

[0038] As described below, the double coil 212 in this embodiment is configured to suppress a local increase in maximum amplitude due to the overlap of the two standing waves, and is configured to form a doughnut-shaped plasma by inductive coupling near the electrical midpoint and the ground position of the electric wires of the first coil 212a and the second coil 212b by supplying high-frequency power to each of the first coil 212a and the second coil 212b, thereby flattening the plasma distribution. That is, by supplying high-frequency power to each of the first coil 212a and the second coil 212b while a processing gas is supplied to the plasma generation space 201a, plasma is generated in the plasma generation space 201a by the action of the high-frequency voltage and the high-frequency current according to the above-mentioned principle, and the processing gas activated by the plasma, i.e., the processing gas in a radical state, promotes a reaction with the wafer 200.

[0039] Furthermore, by using the double coil 212, it is possible to generate a larger amount of plasma than with a single coil. That is, it is possible to increase the amount of radicals generated by the plasma. Therefore, for example, it is possible to supply a sufficient amount of radicals that can reach the bottom of a deep groove formed on the wafer 200, which is the substrate to be processed, and therefore it is possible to sufficiently process the bottom of the deep groove.

[0040] (Double coil structure) Next, the structure of the double coil 212, which is a plasma generation structure having at least two coils, will be described in detail with reference to FIGS. 3, 4(A) and 4(B).

[0041] As described above, the double coil 212 is composed of the first coil 212a and the second coil 212b, and is wound spirally multiple times around the outer periphery of the processing vessel 203. The centers of the first coil 212a and the second coil 212b are each located at the center of the processing vessel 203, and the first coil 212a and the second coil 212b are alternately arranged at equal intervals in the vertical direction.

[0042] Here, "along the outer periphery of the processing vessel 203" means that the double coil 212 and the outer periphery (outer surface, outer wall) of the processing vessel 203 are close enough that the high-frequency electromagnetic field generated by the double coil 212 substantially excites the processing gas in the processing vessel 203 into plasma.

[0043] First coil 212a and second coil 212b have approximately the same diameter and approximately the same length, and the winding diameter, winding pitch, and number of turns are set so as to resonate at a constant wavelength in order to form a standing wave of a predetermined wavelength. In other words, it is desirable that the lengths of first coil 212a and second coil 212b be set to lengths corresponding to an integer multiple (1x, 2x, ...) of a quarter wavelength at a predetermined frequency of high frequency power supplied from high frequency power sources 273 and 283, respectively.

[0044] Specifically, taking into consideration the power to be applied, the strength of the magnetic field to be generated, the external dimensions of the device to be used, etc., the first coil 212a and the second coil 212b are each set to a width of 50 to 300 mm so that a magnetic field of about 0.01 to 10 gauss can be generated by high frequency power of 800 kHz to 50 MHz and 0.1 to 10 kW. 2 The coil has an effective cross-sectional area of ​​200 to 500 mm and a coil diameter of 200 to 500 mm, and is wound around the outer periphery of the chamber that forms the plasma generating space by about 2 to 60 turns.

[0045] Here, "substantially the same diameter" means that the wire diameters of the first coil 212a and the second coil 212b are the same, with an error of about ±10%. Furthermore, "substantially the same length" means that the lengths from the power feed point to the ground point of the first coil 212a and the second coil 212b are the same, with an error of about ±10%. In this way, by configuring the double coil 212 with the first coil 212a and the second coil 212b having substantially the same diameter and substantially the same length, it becomes easy to suppress the occurrence of abnormal discharge. In this embodiment, "substantially the same diameter" may simply be expressed as "the same diameter," and "substantially the same length" may also be expressed as "the same length."

[0046] The winding pitches of the first coil 212a and the second coil 212b are set to be equal to each other. The winding diameters (diameters) of the first coil 212a and the second coil 212b are set to be larger than the diameter of the wafer 200 and the outer diameter of the processing vessel 203. The winding diameters of the first coil 212a and the second coil 212b are constant and substantially the same at any position. That is, the coil separation distance d from the outer wall surface (outer peripheral surface) of the upper vessel 210 to the inner diameter side surfaces (surfaces facing the side wall of the upper vessel 210, i.e., inner peripheral surfaces) of the first coil 212a and the second coil 212b is constant, and the winding diameters are substantially the same. Here, "substantially the same winding diameter" means that the winding diameters of the first coil 212a and the second coil 212b are the same with an error of about ±10%.

[0047] Materials that can be used to form the first coil 212a and the second coil 212b include copper pipes, copper thin plates, aluminum pipes, aluminum thin plates, and polymer belts coated with copper or aluminum by vapor deposition.

[0048] The first coil 212a has a power supply point 303 at the end position of the spiral where the spiral is spaced apart from the processing vessel 203 by the coil separation distance d, and a grounding point 304 at the end position of the spiral where the spiral is spaced apart from the processing vessel 203 by the coil separation distance d. A high-frequency power supply unit 271 is connected to the power supply point 303.

[0049] The second coil 212b has a power supply point 305 at the end position of the spiral where the spiral is spaced apart from the processing vessel 203 by the coil separation distance d, and a grounding point 306 at the end position of the spiral where the spiral is spaced apart from the processing vessel 203 by the coil separation distance d. A high-frequency power supply unit 281 is connected to the power supply point 305.

[0050] In first coil 212a, as shown by the solid line in FIG. 4(B), the high frequency wave propagating through first coil 212a is reflected at the end and returns to feed point 303. In this embodiment, the end of first coil 212a is grounded, so the reflection coefficient is approximately -1, and the phase difference between the traveling wave and the reflected wave is approximately 180°. Waves superimposed with this phase difference are generated on the coil wire as standing waves. Furthermore, the phase difference (power factor) between the high frequency voltage and high frequency current at resonance is approximately 90°.

[0051] In the double coil 212 of this embodiment, the plasma distribution due to the first coil 212a and the plasma distribution due to the second coil 212b are flattened in the circumferential direction by arranging the ground point 304, which is the end position of the spiral of the first coil 212a, and the ground point 306, which is the end position of the spiral of the second coil 212b, so that they do not overlap with each other within at least a range of ±30° from each other, preferably at approximately ±90° or approximately ±180° from each other, with the center of the inner diameter of the double coil 212 as the axis. That is, in the double coil 212, the ground point 306 of the second coil 212b is rotated by, for example, ±90° or ±180° with the center of the inner diameter of the double coil 212 as the axis so that the range of ±30° from the ground point 306 of the second coil 212b does not overlap with the range of ±30° from the ground point 304 of the first coil 212a. Because the waveform of the standing wave described above is a sine wave, by placing the first coil 212a and the second coil 212b within the aforementioned range, the amplitude width of the overlapping standing waves is equal to or less than the amplitude width of a single standing wave. That is, the overlapping value of the amplitudes of the standing waves generated by each coil is configured to be smaller than the peak amplitude value of the standing wave. Specifically, the overlapping value of the amplitude width of the standing wave generated by the first coil 212a and the amplitude width of the standing wave generated by the second coil 212b is configured to be smaller than the peak amplitude value of the standing wave generated by either coil.

[0052] This has the effect of reducing a local increase in maximum amplitude due to overlap of standing waves. That is, the line connecting ground point 304 of first coil 212a and the center of the inner diameter of double coil 212 and the line connecting ground point 306 of second coil 212b and the center of the inner diameter of double coil 212 are positioned so as not to overlap each other at least within a range of ±30°, that is, the angle between the line connecting ground point 304 and the center of the inner diameter of double coil 212 and the line connecting ground point 306 and the center of the inner diameter of double coil 212 is 30° to 330°, and more preferably ±90° or ±180°.

[0053] In this disclosure, the expression "within the range of ±30°" means that the lower limit and upper limit are not included in the range. Therefore, it means "greater than -30° and smaller than +30°." Furthermore, in this disclosure, the expression of a numerical range such as "30° to 330°" means that the lower limit and upper limit are included in the range. Therefore, for example, "30° to 330°" means "greater than 30° and less than 330°." The same applies to other numerical ranges.

[0054] Then, high-frequency power is supplied to first coil 212a and second coil 212b from high-frequency power supplies 273 and 283 via feed point 303 and feed point 305, respectively, and standing waves of high-frequency current and high-frequency voltage are formed in sections (also referred to as sections to the ground positions) between first coil 212a and second coil 212b and ground points 304 and 306, respectively. By arranging the electrical midpoint of first coil 212a and the electrical midpoint of second coil 212b at different positions in the circumferential direction, as shown by the dashed lines in Fig. 4(B), the maximum amplitude position of the standing wave in first coil 212a (solid line in Fig. 4(B)) and the maximum amplitude position of the standing wave in second coil 212b (dashed line in Fig. 4(B)) are shifted, thereby suppressing a local increase in maximum amplitude due to overlap of standing waves. As a result, the plasma generated within the processing vessel 203 is flattened in the circumferential direction, thereby reducing damage caused by the plasma to quartz components and the like within the processing vessel 203, and improving the in-plane uniformity of substrate processing.

[0055] In other words, the first coil 212a and the second coil 212b are arranged so that the antinodes of the standing waves do not overlap. Also, the distance between the first coil 212a and the second coil 212b is set to a distance that prevents arc discharge between the conductors of each double coil 212.

[0056] That is, in double coil 212, first coil 212a and second coil 212b are provided with power feed points, and high-frequency power is supplied from high-frequency power supplies 273 and 283, with the amplitude of the standing wave of the high-frequency current being maximum near the electrical midpoint and ground point 304 of first coil 212a and near the electrical midpoint and ground point 306 of second coil 212b. That is, the amplitude of the standing wave of the high-frequency voltage is minimum (ideally zero) and maximum at the electrical midpoints of each coil of double coil 212 and at ground points 304 and 306 of double coil 212.

[0057] A strong high-frequency magnetic field is formed near the electrical midpoint of the first coil 212a and the electrical midpoint of the second coil 212b, where the amplitude of the high-frequency current is maximum, and the processing gas supplied into the plasma generation space 201a in the upper vessel 210 is converted into plasma. Hereinafter, the processing gas is converted into a plasma state called inductively coupled plasma (ICP) by the high-frequency magnetic field formed near the position (region) where the amplitude of the high-frequency current is large. The ICP is generated in a doughnut shape in a region near the electrical midpoint of the first coil 212a and the second coil 212b in the space along the inner wall surface of the upper vessel 210, and uniform plasma is formed in the in-plane direction while diffusing toward the wafer 200.

[0058] (Control unit) The controller 221 as a control unit is configured to control the APC valve 242, the valve 243b and the vacuum pump 246 through signal line A, the susceptor lifting mechanism 268 through signal line B, the heater power adjustment mechanism 276 and the impedance variable mechanism 275 through signal line C, the gate valve 244 through signal line D, the RF sensors 272, 282, the high-frequency power supplies 273, 283 and the matching boxes 274, 284 through signal line E, and the MFCs 252a to 252c and the valves 253a to 253c, 243a through signal line F.

[0059] 5, controller 221, which is a control unit (control means), is configured as a computer including a CPU (Central Processing Unit) 221a, RAM (Random Access Memory) 221b, storage device 221c, and I / O port 221d. RAM 221b, storage device 221c, and I / O port 221d are configured to be able to exchange data with CPU 221a via internal bus 221e. An input / output device 225 configured as, for example, a touch panel or a display is connected to controller 221.

[0060] The storage device 221c is configured with, for example, a flash memory, an HDD (Hard Disk Drive), etc. Control programs for controlling the operation of the substrate processing apparatus, program recipes describing procedures and conditions for substrate processing (described later), etc. are readably stored in the storage device 221c. A process recipe is a combination of procedures in a substrate processing step (described later) that are executed by the controller 221 to obtain a predetermined result, and functions as a program. Hereinafter, the program recipes, control programs, etc. are collectively referred to simply as programs. Note that, when the term "program" is used in this specification, it may refer to only a program recipe, only a control program, or both. The RAM 221b is configured as a memory area (work area) for temporarily storing programs, data, etc. read by the CPU 221a.

[0061] The I / O port 221d is connected to the above-mentioned MFCs 252a to 252c, valves 253a to 253c, 243a, 243b, gate valve 244, APC valve 242, vacuum pump 246, heater 217b, RF sensors 272, 282, high-frequency power supplies 273, 283, matching boxes 274, 284, susceptor lifting mechanism 268, impedance variable mechanism 275, heater power adjustment mechanism 276, etc.

[0062] The CPU 221a is configured to read and execute a control program from the storage device 221c, and also to read a process recipe from the storage device 221c in response to an input of an operation command from the input / output device 225, etc. The CPU 221a is configured to control the opening adjustment operation of the APC valve 242, the opening / closing operation of the valve 243b, and the start / stop of the vacuum pump 246 via the I / O port 221d and signal line A, the lifting operation of the susceptor lifting mechanism 268 via signal line B, the adjustment operation (temperature adjustment operation) of the amount of power supplied to the heater 217b by the heater power adjustment mechanism 276 and the impedance value adjustment operation by the impedance variable mechanism 275 via signal line C, the opening / closing operation of the gate valve 244 via signal line D, the operations of the RF sensors 272, 282, the matching boxes 274, 284, and the high-frequency power supplies 273, 283 via signal line E, and the flow rate adjustment operation of various process gases by the MFCs 252a to 252c and the opening / closing operation of the valves 253a to 253c, 243a via signal line F, etc., in accordance with the contents of the read process recipe.

[0063] The controller 221 can be configured by installing the above-mentioned program stored in an external storage device (for example, a magnetic tape, a magnetic disk such as a flexible disk or a hard disk, an optical disk such as a CD or a DVD, a magneto-optical disk such as an MO, or a semiconductor memory such as a USB memory or a memory card) 226 into a computer. The storage device 221c and the external storage device 226 are configured as computer-readable recording media. Hereinafter, these will be collectively referred to simply as recording media. In this specification, when the term "recording medium" is used, it may include only the storage device 221c alone, only the external storage device 226 alone, or both. Note that the program may be provided to the computer using a communication means such as the Internet or a dedicated line, without using the external storage device 226.

[0064] (2) Substrate processing process Next, a substrate processing process according to one embodiment of the present disclosure will be described mainly with reference to FIG. 6. FIG. 6 is a flow chart showing the substrate processing process according to one embodiment of the present disclosure. The substrate processing process according to one embodiment of the present disclosure is performed by the above-described substrate processing apparatus 100 as one step in a manufacturing process for a semiconductor device such as a flash memory. In the following description, the operation of each part constituting the substrate processing apparatus 100 is controlled by a controller 221.

[0065] Although not shown, trenches having high aspect ratio unevenness are formed in advance on the surface of the wafer 200 to be processed in the substrate processing step according to one embodiment of the present disclosure. In one embodiment of the present disclosure, a layer of, for example, silicon (Si) exposed on the inner wall of the trench is subjected to an oxidation treatment using plasma.

[0066] (Substrate loading process S110) First, the wafer 200 is loaded into the processing chamber 201. Specifically, the susceptor lifting mechanism 268 lowers the susceptor 217 to a transfer position for the wafer 200, and the wafer push-up pins 266 penetrate the through-holes 217a of the susceptor 217. As a result, the wafer push-up pins 266 protrude by a predetermined height from the surface of the susceptor 217.

[0067] Next, the gate valve 244 is opened, and the wafer 200 is loaded into the processing chamber 201 from a vacuum transfer chamber adjacent to the processing chamber 201 using a wafer transfer mechanism (not shown). The loaded wafer 200 is supported in a horizontal position on wafer push-up pins 266 protruding from the surface of the susceptor 217. After the wafer 200 has been loaded into the processing chamber 201, the wafer transfer mechanism is retracted to the outside of the processing chamber 201, and the gate valve 244 is closed to hermetically seal the processing chamber 201. Then, the susceptor lift mechanism 268 lifts the susceptor 217, so that the wafer 200 is supported on the upper surface of the susceptor 217.

[0068] (Heating and evacuation process S120) Next, the temperature of the wafer 200 loaded into the processing chamber 201 is increased. The heater 217b is preheated, and the wafer 200 is held on the susceptor 217 in which the heater 217b is embedded, thereby heating the wafer 200 to a predetermined temperature within a range of, for example, 25 to 800°C. While the temperature of the wafer 200 is being increased, the processing chamber 201 is evacuated via the gas exhaust pipe 231 by the vacuum pump 246, and the pressure inside the processing chamber 201 is set to a predetermined value. The vacuum pump 246 is kept operating at least until the substrate unloading step S160, which will be described later, is completed.

[0069] (Reaction gas supply process S130) Next, the supply of oxygen-containing gas and hydrogen-containing gas as reactive gases is started. Specifically, the valves 253a and 253b are opened, and the supply of oxygen-containing gas and hydrogen-containing gas into the processing chamber 201 is started while controlling the flow rates with the MFCs 252a and 252b. At this time, the flow rate of the oxygen-containing gas is set to a predetermined value within a range of, for example, 20 to 2000 sccm. Also, the flow rate of the hydrogen-containing gas is set to a predetermined value within a range of, for example, 20 to 1000 sccm.

[0070] Furthermore, the opening of the APC valve 242 is adjusted to control exhaust from the processing chamber 201 so that the pressure inside the processing chamber 201 becomes a predetermined pressure, for example, within a range of 1 to 250 Pa. In this way, while the processing chamber 201 is appropriately exhausted, the supply of the oxygen-containing gas and the hydrogen-containing gas continues until the end of the plasma processing step S140, which will be described later.

[0071] Examples of oxygen-containing gases that can be used include oxygen (O2) gas, nitrous oxide (N2O) gas, nitric oxide (NO) gas, nitrogen dioxide (NO2) gas, ozone (O3) gas, water vapor (H2O gas), carbon monoxide (CO) gas, carbon dioxide (CO2) gas, etc. One or more of these can be used as the oxygen-containing gas.

[0072] Furthermore, examples of the hydrogen-containing gas that can be used include hydrogen (H2) gas, deuterium (D2) gas, H2O gas, and ammonia (NH3) gas. One or more of these can be used as the hydrogen-containing gas. When H2O gas is used as the oxygen-containing gas, it is preferable to use a gas other than H2O gas as the hydrogen-containing gas, and when H2O gas is used as the hydrogen-containing gas, it is preferable to use a gas other than H2O gas as the oxygen-containing gas.

[0073] As the inert gas, for example, nitrogen (N2) gas can be used, and other rare gases such as argon (Ar) gas, helium (He) gas, neon (Ne) gas, xenon (Xe) gas, etc. One or more of these can be used as the inert gas.

[0074] (Plasma treatment step S140) Once the pressure inside the processing chamber 201 has stabilized, high frequency power is simultaneously applied to the first coil 212a and the second coil 212b from the high frequency power sources 273 and 283 via the RF sensors 272 and 282 and the matching devices 274 and 284, respectively.

[0075] As a result, a high-frequency electromagnetic field is formed in the plasma generation space 201a to which the oxygen-containing gas and the hydrogen-containing gas are supplied, and this electromagnetic field excites donut-shaped ICPs with the highest plasma density at height positions corresponding to the electrical midpoints of the first coil 212a and the second coil 212b in the plasma generation space 201a. Furthermore, when both ends of the first coil 212a and the second coil 212b are grounded, ICPs are also excited at the height positions of the lower and upper ends of each. The plasma-like oxygen-containing gas and hydrogen-containing gas dissociate, generating reactive species such as oxygen radicals (oxygen active species) and oxygen ions containing oxygen, and hydrogen radicals (hydrogen active species) and hydrogen ions containing hydrogen.

[0076] Radicals generated by the induced plasma are uniformly supplied into the trench of the wafer 200 held on the susceptor 217 in the substrate processing space 201b. The supplied radicals react uniformly with the sidewall and modify the surface layer (e.g., a Si layer) into an oxide layer (e.g., a Si oxide layer) with good step coverage.

[0077] After that, after a predetermined processing time, for example, 10 to 300 seconds, the power output from the high frequency power supplies 273, 283 is stopped to stop the plasma discharge in the processing chamber 201. Furthermore, the valves 253a and 253b are closed to stop the supply of the oxygen-containing gas and the hydrogen-containing gas into the processing chamber 201. This completes the plasma processing step S140.

[0078] (Vacuum evacuation process S150) After the supply of the oxygen-containing gas and the hydrogen-containing gas is stopped, the processing chamber 201 is evacuated via the gas exhaust pipe 231. This allows the oxygen-containing gas and the hydrogen-containing gas in the processing chamber 201, as well as exhaust gases generated by the reaction of these gases, to be exhausted to the outside of the processing chamber 201. Thereafter, the opening of the APC valve 242 is adjusted to adjust the pressure in the processing chamber 201 to the same pressure as that of a vacuum transfer chamber (the destination of the wafer 200, not shown) adjacent to the processing chamber 201.

[0079] (Substrate unloading process S160) When the inside of the processing chamber 201 reaches a predetermined pressure, the susceptor 217 is lowered to the transfer position of the wafer 200, and the wafer 200 is supported on the wafer lift-up pins 266. Then, the gate valve 244 is opened, and the wafer 200 is transferred out of the processing chamber 201 using the wafer transfer mechanism.

[0080] This completes the substrate processing process according to one aspect of the present disclosure.

[0081] (3) Variations The double coil 212 in the above-described embodiment can be modified as shown below. Unless otherwise specified, the configuration of each modification is the same as the configuration in the above-described embodiment, and therefore, description thereof will be omitted.

[0082] (Variation 1) Modification 1 will be described with reference to FIGS. 7(A) and 7(B). In this modification, an element 400 having an arbitrary impedance is connected to and grounded at the end position of the spiral of at least one of the first coil 212a and the second coil 212b constituting the above-described double coil 212. Specifically, the element 400 having an arbitrary impedance is connected to and grounded at the ground point 306 of the second coil 212b.

[0083] By adjusting the impedance of element 400, it is possible to adjust the position where the standing wave occurs in second coil 212b, and it is possible to change the peak position of the high-frequency current. That is, as shown in Fig. 7(B), the peak position of the high-frequency current of the standing wave (dashed line in Fig. 7(B)) in second coil 212b is adjusted to be shifted from the peak position of the high-frequency current of the standing wave (solid line in Fig. 7(B)) in first coil 212a, thereby suppressing a local increase in maximum amplitude due to overlap of standing waves.

[0084] In this way, by connecting an element 400 having an arbitrary impedance to the ground point of one of the double coils 212, it is possible to suppress a local increase in maximum amplitude due to overlap of standing waves, as in the above-described embodiment, reduce damage caused by plasma to quartz members, etc. in the processing vessel 203 made of quartz or the like that constitutes the processing chamber 201, and improve the in-plane uniformity of the substrate processing.

[0085] (Variation 2) The second modification will be described with reference to FIG. In this modification, in the double coil 212, the ground point 306 of the second coil 212b is rotated, for example, 90° from the ground point 304 of the first coil 212a around the center of the inner diameter of the double coil 212. The positions of the power feed point 303 and the ground point 304 of the first coil 212a are approximately the same in the circumferential direction but different in the vertical direction. The positions of the power feed point 305 and the ground point 306 of the second coil 212b are approximately the same in the circumferential direction but different in the vertical direction. Here, "approximately the same" means that the positions of the power feed point and the ground point of each coil are the same within an error of about ±10%. In other words, the power feed point 303 and the ground point 304 of the first coil 212a are located on the same side in the circumferential direction of the double coil 212, and the power feed point 305 and the ground point 306 of the second coil 212b are located on the same side in the circumferential direction of the double coil 212.

[0086] The first coil 212a and the second coil 212b have substantially the same diameter and length and are wound around the outer periphery of the processing vessel 203 an odd number of times. This allows the peak value of the high-frequency current at the electrical midpoint of each of the first coil 212a and the second coil 212b to be located on the opposite side (opposite side) of the power supply point and the ground point, respectively, thereby dispersing the peak value of the high-frequency current in the standing wave. Therefore, the peak positions of the high-frequency current in the standing wave are configured not to overlap between the first coil 212a and the second coil 212b. That is, similar to the above-described embodiment, this configuration suppresses a local increase in the maximum amplitude due to the overlap of standing waves, reduces plasma damage to the processing vessel 203 made of quartz or the like that constitutes the processing chamber 201, and improves in-plane uniformity of substrate processing. Furthermore, this configuration facilitates control to suppress the occurrence of abnormal discharge.

[0087] <Other aspects> Various typical embodiments and modifications of the present disclosure have been described above, but the present disclosure is not limited to these embodiments and can be used in appropriate combinations.

[0088] In the above embodiment, the double coil 212 consisting of the first coil 212a and the second coil 212b is used, but the present invention is not limited to this and can be applied to a case where a coil consisting of three or more coils is used. In this case, the three or more coils are collectively referred to as a plasma generation structure.

[0089] Although the above embodiment describes an example of an oxidation treatment of a substrate surface using plasma, the present invention can also be applied to a nitriding treatment using a nitrogen-containing gas as a treatment gas. It can also be applied to an etching treatment using an etching gas such as a fluorine-containing gas or a chlorine-containing gas as a treatment gas. Furthermore, the present invention is not limited to these. The treatment gas can be at least one gas selected from the group consisting of an oxygen-containing gas, a nitrogen-containing gas, a hydrogen-containing gas, a fluorine-containing gas, and a chlorine-containing gas. It can be applied to any technique of treating a substrate using plasma. For example, it can be applied to a modification treatment or doping treatment of a film formed on a substrate surface using plasma, a reduction treatment of an oxide film, an etching treatment of the film, an ashing treatment of a resist, and the like. This configuration can increase the plasma density, thereby enabling faster processing speeds and forming a more modified film.

[0090] Although the present disclosure has been described in detail with respect to specific embodiments and modifications, it will be apparent to those skilled in the art that the present disclosure is not limited to such embodiments and modifications, and that various other embodiments are possible within the scope of the present disclosure. [Explanation of symbols]

[0091] 200 wafers (substrates) 203 Processing vessel 212 double coil 212a First coil 212b Second coil 271, 281 High frequency power supply unit

Claims

1. a processing vessel in which a processing gas is plasma-excited; a gas supply system configured to supply the process gas into the process vessel; a plasma generation structure including at least two coils wound spirally around the outer periphery of the processing vessel, each coil being supplied with high frequency power, and each coil having a length that is an integral multiple of a quarter wavelength at a predetermined frequency of the high frequency power; At least two of the coils have substantially the same diameter and substantially the same length; The spiral end positions of the coils are arranged at ±90° or ±180° relative to each other in the circumferential direction, The coils are configured so that the antinodes of the standing waves generated by the coils do not overlap, and the overlapping amplitudes are smaller than the peak amplitudes of the standing waves. Substrate processing equipment.

2. 2. The substrate processing apparatus according to claim 1, wherein an element having an arbitrary impedance is connected to an end position of the spiral of at least one of the coils.

3. 2. The substrate processing apparatus according to claim 1, wherein the coil is wound around the outer periphery of the processing vessel an equal odd number of times.

4. 2. The substrate processing apparatus according to claim 1, wherein the processing gas is at least one gas selected from the group consisting of an oxygen-containing gas, a nitrogen-containing gas, a hydrogen-containing gas, a fluorine-containing gas, and a chlorine-containing gas.

5. 3. The substrate processing apparatus according to claim 2, wherein the impedance of said element is adjusted to adjust the peak position of the high frequency current.

6. The substrate processing apparatus according to claim 1 , wherein power is supplied to at least two of the coils simultaneously.

7. The substrate processing apparatus of claim 1 , wherein at least two of the coils are operated simultaneously.

8. The processing vessel comprises: a plasma generation space around which the two coils are provided; a substrate processing space disposed below the plasma generating space; The substrate processing apparatus according to claim 1 , comprising:

9. the plasma generation space is a space above the lower end of the coil, The substrate processing space is a space below the lower end of the coil. The substrate processing apparatus according to claim 8 .

10. The substrate processing apparatus according to claim 1 , wherein the two coils are alternately arranged at equal intervals in the vertical direction.

11. 2. The substrate processing apparatus according to claim 1, wherein the substantially same length indicates that the difference in length between the first coil and the second coil from the power supply point to the installation point is within a range of ±10%.

12. 2. The substrate processing apparatus according to claim 1, wherein the substantially same diameter indicates that the difference in wire diameter between the first coil and the second coil is within a range of ±10%.

13. The winding diameter of the first coil and the winding diameter of the second coil are substantially the same, 2. The substrate processing apparatus according to claim 1, wherein a distance between an inner diameter surface of the first coil and an outer wall surface of the processing vessel and a distance between an inner surface of the second coil and the outer wall surface are constant.

14. 2. The substrate processing apparatus according to claim 1, wherein the coils are configured so that their electrical midpoints are located at different positions in the circumferential direction.

15. In a state where the position of the grounding point of the first coil and the position of the grounding point of the second coil are made different in the circumferential direction, The positions of the power supply point and the ground point of the first coil are substantially the same in the circumferential direction, and the positions of the power supply point and the ground point of the second coil are substantially the same in the circumferential direction. The substrate processing apparatus according to claim 1 .

16. A substrate processing apparatus as described in claim 1, wherein the end position is positioned at a position that is further away than the distance that the coil is away from the side wall of the processing vessel.

17. A substrate processing apparatus as described in claim 1, wherein the power supply position of the coil spiral is positioned at a position that is further away than the distance that the coil is away from the side wall of the processing vessel.

18. The method of claim 17, further comprising: supplying a processing gas into a processing vessel while a substrate is present in the processing vessel; a step of supplying high frequency power to a plasma generation structure, the plasma generation structure including at least two coils wound spirally around the outer periphery of the processing vessel, the coils having a length equal to an integral multiple of a quarter wavelength at a predetermined frequency of the supplied high frequency power, the at least two coils having substantially the same diameter and substantially the same length, the spiral ends of the coils being arranged at ±90° or ±180° relative to each other in the circumferential direction, the plasma generation structure being configured so that antinodes of standing waves generated by the coils do not overlap, and the overlapping amplitudes are smaller than the peak amplitudes of the standing waves; A substrate processing method comprising:

19. The method of claim 19, further comprising: supplying a processing gas into a processing vessel while a substrate is present in the processing vessel; a step of supplying high frequency power to a plasma generation structure, the plasma generation structure including at least two coils wound spirally around the outer periphery of the processing vessel, the coils having a length equal to an integral multiple of a quarter wavelength at a predetermined frequency of the supplied high frequency power, the at least two coils having substantially the same diameter and substantially the same length, the spiral ends of the coils being arranged at ±90° or ±180° relative to each other in the circumferential direction, the plasma generation structure being configured so that antinodes of standing waves generated by the coils do not overlap, and the overlapping amplitudes are smaller than the peak amplitudes of the standing waves; A method for manufacturing a semiconductor device having the above structure.

20. The method of claim 1, further comprising the steps of: supplying a processing gas into a processing vessel while a substrate is present in the processing vessel; supplying high frequency power to a plasma generation structure, the plasma generation structure including at least two coils wound spirally around the outer periphery of the processing vessel, the coils having a length that is an integral multiple of a quarter wavelength at a predetermined frequency of the supplied high frequency power, the at least two coils having substantially the same diameter and substantially the same length, the spiral ends of the coils being arranged at positions that are ±90° or ±180° from each other in the circumferential direction, so that antinodes of standing waves generated by the coils do not overlap, and generating plasma in the processing vessel such that the overlapping amplitudes are smaller than the peak amplitudes of the standing waves; A program that causes a computer to execute the above in a substrate processing apparatus.

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