Substrate processing method and substrate processing device

Abstract

Provided are a substrate processing method and a substrate processing device for etching a film.　This substrate processing method comprises a step (a) for preparing a substrate which has, in a recess thereof, a film containing silicon (Si) and / or boron (B), a step (b) for supplying the substrate with a gas containing fluorine (F) to form a fluoridized layer on the surface of the film, and a step (c) for supplying the substrate with nitrogen (N)-containing gas plasma to etch the fluoridized layer. In the step (c), the etched morphology of the film is controlled by adjusting the time during which the substrate is supplied with the nitrogen (N)-containing gas plasma.

Description

Substrate processing method and substrate processing apparatus

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

[0002] Patent Document 1 discloses an etching method for selectively etching a silicon nitride film, which includes a step of introducing HF gas into a processing space and a step of generating argon plasma and introducing argon radicals into the processing space.

[0003] Japanese Patent Application Laid-Open No. 2019-12759

[0004] In one aspect, the present disclosure provides a substrate processing method and a substrate processing apparatus for etching a film.

[0005] In order to solve the above-mentioned problems, according to one aspect, there is provided a substrate processing method comprising the steps of: (a) preparing a substrate having a film containing silicon (Si) and / or boron (B) in a recess; (b) supplying a gas containing fluorine (F) to the substrate to form a fluoride layer on the surface of the film; and (c) supplying a plasma of a gas containing nitrogen (N) to the substrate to etch the fluoride layer, wherein in the step (c), the etching shape of the film is controlled by adjusting the time for which the plasma of the gas containing nitrogen (N) is supplied to the substrate.

[0006] According to one aspect, a substrate processing method and a substrate processing apparatus for etching a film can be provided.

[0007] 1 is a schematic diagram illustrating an example of the configuration of a plasma processing apparatus according to an embodiment; FIG. 2 is a flowchart illustrating an example of a film formation process according to an embodiment; FIG. 3 is a schematic cross-sectional view of a substrate; FIG. 4 is a schematic cross-sectional view of a substrate; FIG. 5 is a schematic cross-sectional view of a substrate; FIG. 6 is a time chart for a film etching process; FIG. 7 is a schematic cross-sectional view of a film before etching; FIG. 8 is a schematic cross-sectional view of a film after etching; FIG. 9 is a schematic cross-sectional view of a film after etching; FIG. 10 is a schematic cross-sectional view of a film after etching;

[0008] Hereinafter, embodiments 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 redundant explanations may be omitted.

[0009] [Substrate Processing Apparatus] A plasma processing apparatus (substrate processing apparatus) 100 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is an example of a schematic diagram showing an example of the configuration of the plasma processing apparatus 100 according to this embodiment.

[0010] The plasma processing apparatus 100 has a cylindrical processing vessel 1 with a ceiling and an open bottom end. The entire processing vessel 1 is made of, for example, quartz. A ceiling plate 2 made of quartz is provided near the upper end of the processing vessel 1, and the area below the ceiling plate 2 is sealed. A cylindrical metal manifold 3 is connected to the opening at the lower end of the processing vessel 1 via a sealing member 4 such as an O-ring.

[0011] The manifold 3 supports the lower end of the processing vessel 1, and a wafer boat 5 (substrate support portion) carrying a large number of semiconductor wafers (hereinafter referred to as "substrates W") (e.g., 25 to 150) stacked as substrates is inserted into the processing vessel 1 from below the manifold 3. In this manner, the processing vessel 1 accommodates the large number of substrates W generally horizontally, with spacing between them in the vertical direction. The wafer boat 5 is made of, for example, quartz. The wafer boat 5 has three rods 6 (two are shown in FIG. 1 ), and the large number of substrates W are supported by grooves (not shown) formed in the rods 6.

[0012] The wafer boat 5 is placed on a table 8 via a heat-retaining cylinder 7 made of quartz. The table 8 is supported on a rotating shaft 10 that passes through a metal (stainless steel) cover 9 that opens and closes the opening at the bottom end of the manifold 3.

[0013] A magnetic fluid seal 11 is provided at the penetration portion of the rotating shaft 10, hermetically sealing and rotatably supporting the rotating shaft 10. A seal member 12 is provided between the peripheral portion of the lid 9 and the lower end of the manifold 3 to maintain airtightness inside the processing vessel 1.

[0014] The rotation shaft 10 is attached to the tip of an arm 13 supported by a lifting mechanism (not shown), such as a boat elevator, and the wafer boat 5 and the lid 9 are raised and lowered as a unit to be inserted into and removed from the processing vessel 1. Note that the table 8 may be fixed to the lid 9 side so that the substrates W can be processed without rotating the wafer boat 5.

[0015] The plasma processing apparatus 100 also includes a gas supply unit 20 that supplies predetermined gases, such as a processing gas and a purge gas, into the processing chamber 1 .

[0016] The gas supply unit 20 has gas supply pipes 21 to 24. The gas supply pipes 21, 22, and 23 are made of, for example, quartz, penetrate the side wall of the manifold 3 inward, bend upward, and extend vertically. A plurality of gas holes 21g, 22g, and 23g are formed at predetermined intervals in the vertical portions of the gas supply pipes 21, 22, and 23 over a length in the vertical direction corresponding to the wafer support range of the wafer boat 5. Each of the gas holes 21g, 22g, and 23g discharges gas horizontally. The gas supply pipe 24 is made of, for example, quartz, and is a short quartz pipe that penetrates the side wall of the manifold 3.

[0017] The gas supply pipe 21 has a vertical portion (the vertical portion where the gas hole 21g is formed) disposed within the processing chamber 1. A first processing gas is supplied to the gas supply pipe 21 from a gas supply source 21a via a gas pipe. The gas pipe is provided with a flow rate controller 21b and an on-off valve 21c. Thus, the first processing gas from the gas supply source 21a is supplied into the processing chamber 1 via the gas pipe and the gas supply pipe 21.

[0018] A vertical portion of the gas supply pipe 22 (the vertical portion where the gas holes 22g are formed) is provided inside the processing chamber 1. A second processing gas is supplied to the gas supply pipe 22 from a gas supply source 22a via a gas pipe. A flow rate controller 22b and an on-off valve 22c are provided on the gas pipe. Thus, the second processing gas from the gas supply source 22a is supplied into the processing chamber 1 via the gas pipe and the gas supply pipe 22.

[0019] The gas supply pipe 23 has a vertical portion (the vertical portion where the gas holes 23g are formed) disposed in a plasma generation space, which will be described later. A third process gas is supplied to the gas supply pipe 23 from a gas supply source 23a via a gas pipe. The gas pipe is provided with a flow rate controller 23b and an on-off valve 23c. As a result, the third process gas from the gas supply source 23a is supplied to the plasma generation space via the gas pipe and the gas supply pipe 23, and is converted into plasma in the plasma generation space, and activated species (ions, radicals, etc.) of the third process gas are supplied into the processing vessel 1.

[0020] A purge gas is supplied to the gas supply pipe 24 from a purge gas supply source (not shown) via a gas pipe. A flow rate controller (not shown) and an on-off valve (not shown) are provided in the gas pipe (not shown). Thus, the purge gas from the purge gas supply source is supplied into the processing chamber 1 via the gas pipe and the gas supply pipe 24. The purge gas may be, for example, nitrogen (N ２ In the above description, the purge gas is supplied from the purge gas supply source into the processing chamber 1 through the gas piping and the gas supply pipe 24, but the present invention is not limited to this, and the purge gas may be supplied from any of the gas supply pipes 21 to 23.

[0021] 1 illustrates a gas supply pipe connected to one gas supply source, but this is not limited thereto. A gas supply pipe may be connected to multiple gas supply sources, and a flow rate controller and an on-off valve provided for each gas supply source may be used to switch between different process gases and supply them to the gas supply pipe. The number of gas supply pipes is not limited to that shown in FIG. 1.

[0022] A plasma generation mechanism 30 is formed on a part of the sidewall of the processing chamber 1. The plasma generation mechanism 30 generates activated species of the third processing gas by converting the third processing gas into plasma.

[0023] The plasma generation mechanism 30 includes a plasma partition wall 32, a pair of plasma electrodes 33 (one of which is shown in FIG. 1), a power supply line 34, a high-frequency power supply 35, and an insulating protective cover 36.

[0024] The plasma compartment wall 32 is airtightly welded to the outer wall of the processing vessel 1. The plasma compartment wall 32 is made of, for example, quartz. The plasma compartment wall 32 has a concave cross section and covers an opening 31 formed in the side wall of the processing vessel 1. The opening 31 is elongated in the vertical direction so as to cover all of the substrates W supported on the wafer boat 5 in the vertical direction. A gas supply pipe 23 for discharging a third processing gas is disposed in an inner space defined by the plasma compartment wall 32 and communicating with the inside of the processing vessel 1, i.e., a plasma generation space.

[0025] A pair of plasma electrodes 33 (one electrode is shown in FIG. 1 ) each have an elongated shape and are arranged facing each other in the vertical direction on the outer surfaces of both sides of the plasma compartment wall 32. Each plasma electrode 33 is held by, for example, a holder (not shown) provided on the side of the plasma compartment wall 32. A power supply line 34 is connected to the lower end of each plasma electrode 33.

[0026] The power supply line 34 electrically connects each plasma electrode 33 to the high-frequency power supply 35. In the illustrated example, one end of the power supply line 34 is connected to the lower end of each plasma electrode 33, and the other end is connected to the high-frequency power supply 35.

[0027] A high-frequency power supply 35 is connected to the lower end of each plasma electrode 33 via a power supply line 34, and supplies high-frequency power of, for example, 13.56 MHz to the pair of plasma electrodes 33. This applies the high-frequency power to the plasma generation space defined by the plasma partition wall 32. The third process gas discharged from the gas supply pipe 23 is converted into plasma in the plasma generation space to which the high-frequency power is applied, and the plasma of the third process gas thus generated is supplied into the processing vessel 1 through the opening 31.

[0028] The insulating protective cover 36 is attached to the outside of the plasma compartment wall 32 so as to cover the plasma compartment wall 32. A coolant passage (not shown) is provided inside the insulating protective cover 36, and cooled nitrogen (N ２The plasma electrode 33 is cooled by flowing a coolant such as a gas through the plasma electrode 33. A shield (not shown) may be provided between the plasma electrode 33 and the insulating protective cover 36 so as to cover the plasma electrode 33. The shield is made of a good conductor such as a metal and is grounded.

[0029] An exhaust port 40 for evacuating the processing vessel 1 is provided in a sidewall portion of the processing vessel 1 opposite the opening 31. The exhaust port 40 is elongated in the vertical direction to correspond to the wafer boat 5. An exhaust port cover member 41 having a U-shaped cross section is attached to the portion of the processing vessel 1 corresponding to the exhaust port 40. The exhaust port cover member 41 extends upward along the sidewall of the processing vessel 1. An exhaust pipe 42 for evacuating the processing vessel 1 through the exhaust port 40 is connected to the lower part of the exhaust port cover member 41. A pressure control valve 43 for controlling the pressure in the processing vessel 1 and an exhaust device 44 including a vacuum pump and the like are connected to the exhaust pipe 42. The processing vessel 1 is evacuated via the exhaust pipe 42 by the exhaust device 44.

[0030] A cylindrical heating mechanism 50 is provided to surround the outer periphery of the processing vessel 1 and heat the processing vessel 1 and the substrate W therein.

[0031] The plasma processing apparatus 100 also includes a control unit 60. The control unit 60 controls the operation of each unit of the plasma processing apparatus 100, for example, by opening and closing the on-off valves 21c to 23c to supply and stop the gases, by controlling the gas flow rates using the flow rate controllers 21b to 23b, and by controlling exhaust using the exhaust device 44. The control unit 60 also controls the on-off of high frequency power from the high frequency power source 35 and the temperature of the substrate W using the heating mechanism 50, for example.

[0032] The control unit 60 may be, for example, a computer. The computer programs that control the operations of each part of the plasma processing apparatus 100 are stored in a storage medium. The storage medium may be, for example, a flexible disk, a compact disk, a hard disk, a flash memory, a DVD, or the like.

[0033] Next, an example of a film formation process using the plasma processing apparatus 100 will be described.

[0034] 2 is a flowchart showing an example of a film forming process according to this embodiment.

[0035] As shown in FIG. 3A , the substrate W has a recess 211 such as a fine trench structure. Specifically, the substrate W has a first layer 200 and a second layer 210. The recess 211 is formed in the second layer 210. In the film formation process according to this embodiment, a film 220 (see FIGS. 3B and 3C ) is embedded in the recess 211. Here, the film 220 may be a film containing silicon (Si) and / or boron (B) (e.g., an Si film, a B film, or an SiB film). Alternatively, the film 220 may be a film containing silicon (Si) and / or boron (B) and nitrogen (N) (e.g., an SiN film, an SiBN film, or an BN film). Alternatively, the film 220 may be a film containing silicon (Si) and / or boron (B), carbon (C), and nitrogen (N) (e.g., an SiCN film, an SiBCN film, or an BCN film).

[0036] In step S101, the control unit 60 executes a deposition process for forming a film 220 on the substrate W.

[0037] In step S102, the control unit 60 executes an etching process to etch the substrate W. This removes the film 220 formed on the upper sidewalls of the recess 211, thereby preventing the upper opening of the recess 211 from being blocked by the film 220. Furthermore, as shown in FIG. 3B , the film 220 fills in the recess 211 from the bottom.

[0038] In step S103, the control unit 60 executes a deposition process to form a film 220 on the substrate W. The deposition process in step S103 may be the same as the deposition process in step S101.

[0039] In step S104, the control unit 60 determines whether the etching step S102 and the deposition step S103 have been repeated a predetermined number of times. If the etching step S102 and the deposition step S103 have not been repeated the predetermined number of times (S104: NO), the control unit 60 returns to step S102, and the etching step S102 and the deposition step S103 are repeated. If the etching step S102 and the deposition step S103 have been repeated the predetermined number of times (S104: YES), the control unit 60 ends the processing. As a result, the film 220 can be embedded in the recess 211 without any voids, as shown in FIG. 3C .

[0040] 2 may be configured to be performed within one plasma processing apparatus 100. Alternatively, the processes shown in FIG. 2 may be performed in a substrate processing system including a first plasma processing apparatus 100 that performs the deposition processes S101 and S103, a second plasma processing apparatus 100 that performs the etching process S102, and a vacuum transfer chamber (not shown) between the first plasma processing apparatus 100 and the second plasma processing apparatus 100.

[0041] 2 is described as being a batch-type plasma processing apparatus 100 that processes a plurality of substrates W. However, the present invention is not limited to this. The processing of this embodiment may also be applied to a single-wafer type plasma processing apparatus.

[0042] <Etching of SiCN Film> Next, the etching step S102 of etching the film 220 will be described with reference to FIG.

[0043] FIG. 4 is an example of a time chart of the etching step S102 of the film 220.

[0044] First, a substrate W having a film 220 containing silicon (Si) and / or boron (B) is prepared by the deposition step S101 (S103) shown in FIG.

[0045] The etching process S102 includes a process S301 of supplying a gas containing fluorine (F) to the substrate W in the processing vessel 1, and a process S302 of supplying a plasma of a gas containing nitrogen (N) to the substrate W in the processing vessel 1, and the processes S301 and S302 are repeated a predetermined number of times.

[0046] In step S301, the control unit 60 controls the on-off valve 21c and the flow rate controller 21b to supply a gas containing fluorine (F) from the gas supply pipe 21 into the processing chamber 1. The gas containing fluorine (F) ２ The fluoride (210) selectively reacts with the film 220 (SiCN film, BN film, etc.) to fluorinate the surface of the film 220, forming a fluoride layer on the surface of the film 220.

[0047] Here, the gas containing fluorine (F) is HF gas, NF ３ Gas, ClF ３ Gas, F ２ Gas, CHF ３ Gas, CH ３ Any gas such as F gas can be used.

[0048] In step S302, the control unit 60 controls the on-off valve 23c and the flow rate controller 23b to supply a gas containing nitrogen (N) from the gas supply pipe 23 into the processing chamber 1. The control unit 60 also controls the high frequency power source 35 to apply high frequency power (RF) to the plasma electrode 33. As a result, activated species (nitrogen radicals) of the gas containing nitrogen (N) react with the fluoride layer formed on the surface of the film 220 to produce reaction products (e.g., SiF ｘ , N.H. ｘ SiF ｙ , B.F. ｘ , N.H. ｘ BF, etc., where x and y are natural numbers. Then, the reaction products are sublimated and desorbed from the surface of the film 220. This removes the fluoride layer formed on the surface of the film 220. In other words, the film 220 is etched by steps S301 and S302.

[0049] Here, the gas containing nitrogen (N) is N ２ Gas, NH ３ Gas, CH３ NH ２ (methylamine) gas, CH ３ CH ２ NH ２ (Ethylamine) gas, N ２ H ４ (hydrazine) gas, etc.

[0050] In this manner, the film 220 can be etched by repeating the processes shown in steps S301 and S302.

[0051] In addition, the etching process S102 further includes a process (not shown) of supplying heated gas to the substrate W in the processing vessel 1, and the order of processes S301, S302, and the process (not shown) of supplying heated gas constitutes one cycle, and this cycle may be repeated a predetermined number of times.

[0052] In the step of supplying a heated gas (not shown), the control unit 60 supplies a heated purge gas into the processing chamber 1 from a gas supply pipe (not shown). The plasma processing apparatus 100 may be configured to supply a heated purge gas to the gas supply pipe and discharge the heated purge gas from gas holes onto the substrate W. The plasma processing apparatus 100 may be configured to supply a purge gas to the gas supply pipe, heat the purge gas by a heater provided in the gas supply pipe disposed in the processing chamber 1, and discharge the heated purge gas from gas holes onto the substrate W. The purge gas may be an inert gas (e.g., N ２ gas, Ar gas, etc.) can be used.

[0053] The temperature of the purge gas discharged from the gas holes is preferably higher than the sublimation temperature of the reaction product, for example, the temperature of the heated gas is preferably 100° C. or higher.

[0054] Specifically, the film 220 is a SiCN film, and the fluorine-containing gas is HF gas, and the nitrogen-containing gas is N ２ When gas is used, the reaction product is SiF ４ , (NH ４ ) ２ SiF ６ , C.F. ４ , C.H. ４In this case, the temperature of the heated gas is preferably 100° C. or higher. In addition, when the film 220 is a BN film, HF gas is used as the fluorine-containing gas, and N gas is used as the nitrogen-containing gas, ２ When gas is used, the reaction product is BF ３ In this case, the temperature of the heated gas is preferably 100° C. or higher.

[0055] As a result, the substrate W is heated by the heating gas, and reaction products are sublimated and exhausted to the outside of the processing chamber 1 through the exhaust port 40 .

[0056] Next, control of the etching shape of the film 220 in the etching step S102 will be described with reference to FIGS.

[0057] 5 is a cross-sectional view showing an example of the shape of the film before etching. In this example, the first layer 200 is made of Si, and the second layer 210 having the recessed portion pattern is made of SiO. ２ An example will be described in which the film 220 embedded in the recess is a BN film.

[0058] 6 to 9 are examples of schematic cross-sectional views showing the shape of the etched film 220. FIG.

[0059] In FIG. 6, the supply time of HF gas in step S301 is 30 seconds, and the supply time of N ２ The time for supplying the gas plasma is set to 30 seconds, and the order of step S301 and step S302 is defined as one cycle. This cycle was repeated 50 times, and the results shown in Fig. 7 are for 75 cycles.

[0060] 6 and 7, in the etching step S102, the etching amount of the film 220 increases as the number of cycles increases. In other words, the etching amount of the film 220 can be controlled by controlling the number of cycles. ２ The BN film (film 220) can be selectively etched relative to the second layer 210.

[0061] Furthermore, the film 220 can be etched without using fluorine (F) radicals. In other words, by using fluorine (F) radicals, it is possible to prevent fluorine (F) from remaining in other films (e.g., the second layer 210).

[0062] In FIG. 8, the supply time of HF gas in step S301 is 30 seconds, and the supply time of N ２ The time for supplying the gas plasma is set to 15 seconds, and the order of step S301 and step S302 is defined as one cycle. This cycle was repeated 50 times, and the results are shown.

[0063] In FIG. 9, the supply time of HF gas in step S301 is 30 seconds, and the supply time of N ２ The time for supplying the gas plasma is set to 60 seconds, and the order of step S301 and step S302 is defined as one cycle. This cycle was repeated 50 times, and the results are shown.

[0064] As shown in comparison of FIGS. 6, 8 and 9, the control unit 60 ２ The shape of the film 220 embedded in the recess is controlled by adjusting the time for supplying the gas plasma.

[0065] Here, the cross section of the upper surface of the etched film 220 is V-shaped. ２ The angle of the V-shape on the upper surface of the film 220 when the time for supplying the gas plasma is shortened (15 seconds) is defined as angle θ1. ２ The angle of the V-shape on the upper surface of the film 220 when the time for supplying the gas plasma is extended (60 seconds) is defined as angle θ2. ２ By controlling the time for supplying the gas plasma, the angle of the V-shape on the upper surface of the film 220 can be controlled. ２ By increasing the time for supplying the gas plasma, the angle of the V-shape can be reduced (angle θ2 shown in FIG. 9). ２ By shortening the time for supplying the gas plasma, the angle of the V-shape can be increased (angle θ1 shown in FIG. 9).

[0066] The above describes the film formation method of this embodiment using the plasma processing apparatus 100, but the present disclosure is not limited to the above embodiment, etc., and various modifications and improvements are possible within the scope of the gist of the present disclosure described in the claims.

[0067] This application claims priority based on Japanese Patent Application No. 2024-030259, filed on February 29, 2024, the entire contents of which are incorporated herein by reference.

[0068] REFERENCE SIGNS LIST 1 Processing vessel 5 Wafer boat (substrate support section) 20 Gas supply section 30 Plasma generation mechanism (plasma generation section) 60 Control section 100 Plasma processing apparatus (substrate processing apparatus) 211 Recess 220 Film W Substrate

Claims

1. A substrate processing method comprising: (a) preparing a substrate having a film containing silicon (Si) and / or boron (B) in a recess; (b) supplying a gas containing fluorine (F) to the substrate to form a fluoride layer on the surface of the film; and (c) supplying a plasma of a gas containing nitrogen (N) to the substrate to etch the fluoride layer, wherein in the step (c), the etching shape of the film is controlled by adjusting the time for which the plasma of the gas containing nitrogen (N) is supplied to the substrate.

2. The substrate processing method according to claim 1, wherein the steps (b) and (c) are repeated multiple times in this order.

3. The substrate processing method according to claim 1, wherein the film is one of a SiCN film, a BN film, and a B film.

4. The fluorine (F)-containing gas is HF gas, NF ３ Gas, ClF ３ Gas, F ２ Gas, CHF ３ Gas, CH ３ The substrate processing method according to claim 1 , further comprising the step of:

5. The nitrogen (N)-containing gas is N ２ Gas, NH ３ Gas, CH ３ NH ２ Gas, CH ３ CH ２ NH ２ Gas, N ２ H ４ The substrate processing method according to claim 1 , further comprising the step of:

6. The substrate processing method according to claim 1, wherein in step (c), the longer the time for which the plasma of the gas containing nitrogen (N) is supplied to the substrate, the smaller the angle of the upper surface of the film in the recess after etching.

7. A substrate processing apparatus comprising: a substrate support part that supports a substrate; a processing vessel that houses the substrate support part; a gas supply part that supplies gas to the processing vessel; a plasma generation part that generates plasma of the gas; and a control part, wherein the control part performs the following steps: (a) preparing a substrate having a film containing silicon (Si) and / or boron (B) and at least nitrogen (N) in a recess; (b) supplying a gas containing fluorine (F) to the substrate to form a fluoride layer on the surface of the film; and (c) supplying plasma of a gas containing nitrogen (N) to the substrate to etch the fluoride layer, and in the step (c), controlling the etching shape of the film by adjusting the time for which the plasma of the gas containing nitrogen (N) is supplied to the substrate.

Images