Plasma processing method and plasma processing apparatus

Abstract

To reduce deviation of plasma density distribution within a reaction chamber.SOLUTION: A plasma processing method is provided in an exemplary embodiment. This method comprises the steps of: a) acquiring temperature information on a reaction chamber at plasma processing time as information indicating a plasma density state using at least one temperature detection element that is provided in an upper electrode of a plasma processing apparatus; and b) converting the temperature information to power information and adjusting power to be supplied to the reaction chamber from a high frequency power source through the upper electrode to reduce deviation of plasma density distribution along an electrode surface of the upper electrode, on the basis of the power information. The upper electrode has an air gap that is provided adjacent to the electrode surface above the electrode surface exposed to the reaction chamber, and at least one temperature detection element includes a first temperature detection element that is arranged to measure bottom part temperature of the air gap.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY Exemplary embodiments of the present disclosure relate to a plasma processing method and a plasma processing apparatus. [Background technology]

[0002] In the manufacture of electronic devices such as semiconductor devices, for example, parallel plate plasma processing apparatuses are used. In the plasma processing apparatus, it is required to make the plasma distribution uniform on the wafer, and techniques for adjusting the electromagnetic waves used to generate the plasma in order to make the plasma distribution uniform are disclosed in Patent Documents 1 to 3. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-73836 A [Patent Document 2] JP 2016-31955 A [Patent Document 3] JP 2022-520797 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for reducing bias in plasma density distribution in a reaction chamber. [Means for solving the problem]

[0005] In one exemplary embodiment, a plasma processing method is provided. The plasma processing method includes steps a) and b). In step a), temperature information of a reaction chamber during plasma processing is obtained as information indicating a state of plasma density using at least one temperature detection element provided in an upper electrode of a plasma processing apparatus. In step b), the temperature information is converted into power information, and based on the power information, the power supplied from a high frequency power source to the reaction chamber via the upper electrode is adjusted so as to reduce a bias in the plasma density distribution along the electrode surface of the upper electrode. The upper electrode has a gap provided adjacent to the electrode surface above the electrode surface exposed to the reaction chamber. The at least one temperature detection element includes a first temperature detection element arranged to measure a bottom temperature of the gap. Effect of the Invention

[0006] According to one exemplary embodiment, the bias in plasma density distribution within the reaction chamber can be reduced. [Brief description of the drawings]

[0007] [Figure 1] 1 illustrates a plasma processing method according to an exemplary embodiment; [Diagram 2] 1 illustrates a plasma processing apparatus according to an exemplary embodiment; [Diagram 3] 2 is a diagram showing an example of an arrangement of two temperature detection elements shown in FIG. 1. [Figure 4] 10A to 10C are diagrams illustrating variations in the planar shape of a gap in which a temperature detection element is disposed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Various exemplary embodiments are described below.

[0009] Various exemplary embodiments will now be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0010] A plasma processing method (method MT) that can be performed using the plasma processing apparatus 1 will be described below with reference to Fig. 1. Fig. 1 is a flow chart showing a plasma processing method according to an exemplary embodiment, and the method MT shown in Fig. 1 is a method for processing a wafer.

[0011] Fig. 2 is a diagram showing an example of a plasma processing apparatus according to an exemplary embodiment. Fig. 2 shows a schematic cross-sectional structure of a plasma processing apparatus 1 that can be used in various embodiments of a method for processing a target object. The plasma processing apparatus 1 shown in Fig. 2 is a parallel plate type plasma processing apparatus. The plasma processing apparatus 1 includes a processing vessel 2, a mounting table 3, a lower electrode 3a, an upper electrode 5, a gas supply unit 13, a high frequency power supply 10, and a shower unit SH.

[0012] The processing vessel 2 is configured to perform plasma processing and is conductive. The processing vessel 2 has a lid 2a and a sidewall 2b. The sidewall 2b and the lid 2a are conductors such as aluminum and are electrically connected to a ground potential. At least a portion of the sidewall 2b of the processing vessel 2 that is exposed to plasma is covered with a liner made of a plasma-resistant material or a liner on which a thermal spray coating made of a plasma-resistant material is formed.

[0013] The processing vessel 2 is formed in a hollow shape (cylindrical shape with a bottom). The central axis of the processing vessel 2 coincides with the central axis of the side wall 2b. An exhaust device 15 is connected to the bottom of the processing vessel 2 via a gas exhaust port 14 in order to reduce the pressure in the processing vessel 2, specifically, in order to reduce the pressure in the reaction chamber 4.

[0014] The lid 2a is formed in a disk shape having a through hole 7c in the center. The lid 2a is provided on the upper side of the side wall 2b. The central axis of the lid 2a and the through hole 7c coincides with the central axis of the side wall 2b.

[0015] A reaction chamber 4 is provided in the processing vessel 2 between a mounting table 3 and an upper electrode 5, both of which are provided in the processing vessel 2. The mounting table 3 has a temperature control mechanism, and is included in a lower electrode 3a.

[0016] The mounting table 3 is configured so that the wafer W is placed thereon below the reaction chamber 4 in the processing vessel 2. The mounting table 3 is supported by a support member 21 that is provided in an upright position at the center of the bottom of the processing vessel 2.

[0017] The mounting table 3 may be provided with a heater (not shown) for heating the wafer W. Instead of a heating mechanism such as a heater, a cooling mechanism having a coolant flow path (not shown) through which a cooling coolant flows may be provided, or both a heating mechanism and a cooling mechanism may be provided. The mounting table 3 is provided with substrate support pins (not shown) that are movable up and down. The substrate support pins are provided to transfer the wafer W between the mounting table 3 and a transfer device (not shown) for the wafer W, which is inserted from outside the processing chamber 2 into the processing chamber 2.

[0018] An upper electrode 5 is provided above the mounting table 3 (above the reaction chamber 4) so ​​as to face the mounting table 3. The upper electrode 5 includes a conductive material such as aluminum, and has a disk shape.

[0019] The upper electrode 5 is supported by the processing vessel 2 via a dielectric ring 6. The dielectric ring 6 is configured to seal between the waveguide 8 and the reaction chamber 4 and supply high frequency power in the VHF band to the reaction chamber 4. The upper electrode 5 and the dielectric ring 6 separate an upper space and a lower space in the processing vessel 2. The upper electrode 5 and the dielectric ring 6 seal the processing vessel 2 so that when the pressure inside the processing vessel 2 is reduced by the exhaust device 15, only the lower space is reduced in pressure. The central axis of the upper electrode 5 coincides with the central axis of the processing vessel 2.

[0020] The upper electrode 5 is provided with a process gas dispersion section 12 formed in a substantially disk shape inside. The process gas dispersion section 12 is a space for diffusing the gas introduced from the gas supply device 13 so as to supply the gas from the shower section SH into the reaction chamber 4. The upper electrode 5 includes a shower section SH provided on the lower part of the upper electrode 5, i.e., on the reaction chamber 4 side. The shower section SH is configured to supply the process gas from the gas supply device 13 to the reaction chamber 4. The shower section SH is provided with a plurality of gas discharge ports 11 communicating with the process gas dispersion section 12. The process gas dispersion section 12 is connected to the gas supply device 13 provided outside the processing vessel 2. The plasma processing gas supplied from the gas supply device 13 is supplied to the process gas dispersion section 12 and then discharged through the gas discharge port 11 into the reaction chamber 4.

[0021] The plasma processing apparatus 1 includes at least one temperature detection element provided in the upper electrode 5 (particularly in the shower part SH). In one embodiment, the plasma processing apparatus 1 may include a temperature sensor T1 (first temperature detection element) and a temperature sensor T2 (second temperature detection element) as shown in FIG. 2 and FIG. 3. That is, the at least one temperature detection element of the plasma processing apparatus 1 may include the temperature sensor T1 and further the temperature sensor T2. The shower part SH of the upper electrode 5 has a temperature measurement space 5b, which is a gap provided adjacent to the electrode surface 5a above the electrode surface 5a exposed to the reaction chamber 4, and the temperature sensor T1 is disposed so as to measure the temperature at the bottom of the temperature measurement space 5b. The shorter the distance from the bottom (bottom surface) of the temperature measurement space 5b to the electrode surface 5a (i.e., the distance from the temperature sensor T1 to the electrode surface 5a), the more preferable, and in this case, the temperature detected by the temperature sensor T1 is closer to the temperature in the reaction chamber 4. The temperature sensor T1 and the temperature sensor T2 may be, for example, a thermocouple, an optical fiber thermometer, or a radiation thermometer.

[0022] The shape of the temperature measurement space 5b may have various variations as shown in FIG. 4. FIG. 4 illustrates variations of the planar shape of the temperature measurement space 5b as viewed from the electrode surface 5a. The temperature measurement space 5b is disposed on the region AR of the electrode surface 5a. The planar shape of the temperature measurement space 5b may be, for example, a perfect circle 5b1, a regular hexagon 5b2, or a rhombus 5b3. Furthermore, the planar shape of the temperature measurement space 5b may be, for example, a rectangular shape 5b4, a square shape 5b5, a sector shape 5b6, or a perfect circle shape 5b7 in which the gas discharge port 11 is provided in the temperature measurement space 5b. Furthermore, the planar shape of the temperature measurement space 5b may be, for example, an elliptical shape 5b8, a shape 5b9 similar to a rectangle whose long side is curved to avoid the gas discharge port 11, or an equilateral triangle shape 5b10.

[0023] 2 and 3, the explanation will be given again. The temperature sensor T1 and the temperature measurement space 5b are provided above a region in the reaction chamber 4 that includes a peak in the plasma density distribution previously measured during plasma processing. The temperature sensor T2 is provided away from the temperature sensor T1. The temperature sensor T2 is provided above a region in the reaction chamber 4 that has a flat distribution in the previously measured plasma density distribution. Note that the plasma density distribution in this disclosure refers to the ion current [μA / cm2] in the plasma in the direction along the electrode surface 5a. 2 ] means the distribution of.

[0024] The temperature sensors T1 and T2 are connected to the temperature information acquisition unit 16 via a dielectric tube TB. The dielectric tube TB is a tube through which wiring passes that connects the temperature sensors T1 and T2 to the temperature information acquisition unit 16. The temperature information acquisition unit 16 is configured to acquire temperature information of the reaction chamber 4 based on temperature signals output from the temperature sensors T1 and T2 (at least one temperature detection element).

[0025] As an example, the temperature information acquired by the temperature information acquiring unit 16 may be a difference obtained by subtracting the second temperature detected by the temperature sensor T2 from the first temperature detected by the temperature sensor T1. The temperature information relating to the difference may be acquired by the temperature information acquiring unit 16 at the timing when the high frequency power is supplied from the high frequency power supply 10 to the upper electrode 5 at the start of the plasma processing (or several seconds after the timing, for example, 4 to 6 seconds).

[0026] As another example, the temperature information acquired by the temperature information acquisition unit 16 may be a difference obtained by subtracting a first temperature detected by the temperature sensor T1 at a first timing from a second temperature detected by the temperature sensor T1 at a second timing after the first timing. The first timing may be the timing at which high frequency power is supplied from the high frequency power supply 10 to the upper electrode 5 at the start of plasma processing (or within a range of several seconds from that timing, for example, 0 to 0.3 seconds). The time from the first timing to the second timing may be, for example, about 0.4 to 0.8 seconds.

[0027] The temperature information acquisition unit 16 is connected to a power adjustment unit 17 that can control the power output from the high frequency power supply 10. The power adjustment unit 17 converts the temperature information acquired by the temperature information acquisition unit 16 into power information. The power adjustment unit 17 controls the high frequency power supply 10 based on the power information so as to reduce the bias of the plasma density distribution along the electrode surface 5a of the upper electrode 5 (shower unit SH). The power adjustment unit 17 is configured to adjust the power supplied from the high frequency power supply 10 to the reaction chamber 4 via the upper electrode 5 by controlling the high frequency power supply 10 in this manner. In this manner, the temperature information of the reaction chamber 4 is converted into power information, and the power information is fed back to the high frequency power supply 10 to adjust the power supplied to the reaction chamber 4, thereby reducing the bias of the plasma density distribution.

[0028] The temperature information may be converted into the power information using, for example, a table that is created in advance for each plasma processing apparatus 1. This table is provided to reduce bias in the plasma density distribution, and may be stored in the memory of the power adjustment unit 17.

[0029] The dielectric ring 6 is provided along the side wall 2b so as to cover the outer circumferential surface of the upper electrode 5. The dielectric ring 6 transmits electromagnetic waves propagating through the waveguide 8 from the high frequency power source 10 via the high frequency matching box 9 into the reaction chamber 4.

[0030] The plasma processing apparatus 1 includes an antenna unit 7. The antenna unit 7 has an inner conductor 7a, an outer conductor 7b, and a through hole 7c.

[0031] The inner conductor 7a is an inner conductor of a coaxial waveguide that is connected to a high-frequency matching box 9. One end of the inner conductor 7a is connected to the center of the upper surface of the upper electrode 5. The central axis of the inner conductor 7a coincides with the central axis of the processing vessel 2. The other end of the inner conductor 7a is electrically connected to a high-frequency power supply 10 via the high-frequency matching box 9.

[0032] The outer conductor 7b is connected to the upper surface of the lid 2a. The central axis of the outer conductor 7b coincides with the central axis of the side wall 2b. The inner diameter of the outer conductor 7b is approximately the same as the diameter of the through hole 7c of the lid 2a.

[0033] The plasma processing apparatus 1 has a waveguide 8. The waveguide 8 propagates an electromagnetic wave generated based on high frequency power output from a high frequency power supply 10 to a reaction chamber 4 via a dielectric ring 6. The waveguide 8 has a first waveguide 8a and a second waveguide 8b.

[0034] The first waveguide 8a is defined by the outer peripheral surface of the inner conductor 7a, the inner peripheral surface of the outer conductor 7b, etc. The first waveguide 8a propagates the electromagnetic wave in the axial direction (vertically downward) along the inner conductor 7a. The second waveguide 8b is continuous with the first waveguide 8a, and is defined by the lower surface of the lid 2a and the upper surface of the upper electrode 5. The second waveguide 8b propagates the electromagnetic wave horizontally outward along the radial direction in a plan view.

[0035] The high frequency power supply 10 is electrically connected to the upper electrode 5 and configured to generate plasma of a processing gas supplied from a gas supply device 13 by supplying high frequency power to the upper electrode 5. The high frequency power output from the high frequency power supply 10 is supplied to the upper electrode 5 via a high frequency matching device 9. The high frequency power supply 10 can output high frequency power in the VHF band, UHF band, or HF band. The high frequency power in the VHF band, UHF band, or HF band is applied to the plasma processing device 1.

[0036] The gas supply device 13 is configured to supply a process gas to the reaction chamber 4 between the upper electrode 5 and the mounting table 3 .

[0037] In the plasma processing apparatus 1, plasma is generated in the reaction chamber 4 by a process gas supplied from the gas supply device 13 and discharged from the gas discharge port 11 into the reaction chamber 4, and by electromagnetic waves propagating to the reaction chamber 4 via the dielectric ring 6. In order to attract ions and the like in the plasma to the wafer W, for example, a high-frequency power source (not shown) for RF bias may be electrically connected to the mounting table 3 via a matching box.

[0038] The plasma processing apparatus 1 further includes a control unit (not shown). The control unit includes a computer having, for example, a CPU, a memory, and the like, and has a program storage unit. The program storage unit stores programs for executing various processes in the plasma processing apparatus 1.

[0039] Returning to Fig. 1, method MT will be described. Method MT includes steps ST1 to ST4, and may be performed each time a plasma process is performed. For example, when an ALD (Atomic Layer Deposition) method is used in the film formation process, method MT may be performed each time a plasma process is repeated multiple times.

[0040] In step ST1, plasma processing is started. In step ST2, the temperature information acquiring unit 16 acquires temperature information of the reaction chamber during plasma processing as information indicating the state of plasma density using at least one temperature detection element (e.g., temperature sensor T1 and temperature sensor T2) provided in the upper electrode 5 (shower part SH). As an example, the temperature information acquiring unit 16 can acquire temperature information when the high frequency power supply 10 is turned on at the start of plasma processing.

[0041] In step ST3 following step ST2, the power adjustment unit 17 converts the temperature information acquired by the temperature information acquisition unit 16 into power information. In step ST4 following step ST3, the power adjustment unit 17 controls the high frequency power supply 10 based on the power information so as to reduce the bias of the plasma density distribution along the electrode surface 5a of the upper electrode 5 (shower unit SH). In this way, the power adjustment unit 17 adjusts the power supplied from the high frequency power supply 10 to the reaction chamber 4 via the upper electrode 5.

[0042] According to the above-mentioned method MT and plasma processing apparatus 1, the deviation of the plasma density distribution can be reduced by the temperature information in the reaction chamber 4 during plasma processing, and a uniform plasma can be obtained. In addition, since a thermocouple, an optical fiber thermometer, or the like can be used as a temperature detection element (e.g., temperature sensors T1, T2), the method MT and plasma processing apparatus 1 can be realized with a simple structure and system at low cost.

[0043] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0044] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E6] below.

[0045] [E1] a) acquiring temperature information of a reaction chamber during plasma processing as information indicating a state of plasma density using at least one temperature detection element provided in an upper electrode of the plasma processing apparatus; b) converting the temperature information into power information, and adjusting the power supplied from a high frequency power source to the reaction chamber via the upper electrode based on the power information so as to reduce bias in plasma density distribution along the electrode surface of the upper electrode; Equipped with the upper electrode has a gap provided above and adjacent to the electrode surface exposed to the reaction chamber; the at least one temperature sensing element includes a first temperature sensing element positioned to measure a temperature at a bottom of the gap; Plasma treatment method.

[0046] [E2] The first temperature detection element is provided above a region including a peak of a plasma density distribution previously measured during plasma processing. The plasma processing method according to [E1].

[0047] [E3] the at least one temperature detection element includes a second temperature detection element spaced apart from the first temperature detection element; The second temperature detection element is provided above a flat region of the previously measured plasma density distribution. The plasma processing method according to [E1] or [E2].

[0048] [E4] The temperature information acquired in the step a) is a difference obtained by subtracting a second temperature detected by the second temperature detection element from a first temperature detected by the first temperature detection element. The plasma processing method according to [E3].

[0049] [E5] the temperature information acquired in the step a) is a difference obtained by subtracting a first temperature detected by the first temperature detection element at a first timing from a second temperature detected by the first temperature detection element at a second timing after the first timing; The plasma processing method according to [E1] or [E2].

[0050] [E6] A processing vessel configured to perform plasma processing; a mounting table provided in the processing chamber and configured to mount a wafer thereon; an upper electrode that is provided in the processing chamber and arranged above the mounting table so as to face the mounting table; a gas supply unit configured to supply a process gas to a reaction chamber between the upper electrode and the mounting table; a radio frequency power source electrically connected to the upper electrode and configured to generate a plasma of the process gas by supplying radio frequency power to the upper electrode; At least one temperature sensing element disposed within the upper electrode; a temperature information acquiring unit configured to acquire temperature information of the reaction chamber based on a temperature signal output from the at least one temperature detecting element; converting the temperature information acquired by the temperature information acquisition unit into power information, and reducing a bias in the plasma density distribution along the electrode surface of the upper electrode based on the power information; a power adjusting unit configured to adjust the power supplied from the high frequency power source to the reaction chamber via the upper electrode; Equipped with the upper electrode has a gap provided above and adjacent to the electrode surface exposed to the reaction chamber; the at least one temperature sensing element includes a first temperature sensing element positioned to measure a temperature at a bottom of the gap; Plasma processing equipment.

[0051] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0052] 1...plasma processing apparatus, 10...high frequency power supply, 11...gas outlet, 12...processing gas dispersion section, 13...gas supply device, 14...gas exhaust port, 15...exhaust device, 16...temperature information acquisition section, 17...power adjustment section, 2...processing vessel, 21...support member, 2a...lid, 2b...side wall, 3...mounting table, 3a...lower electrode, 4...reaction chamber, 5...upper electrode, 5a...electrode surface, 5b...temperature measurement space, 6...dielectric ring, 7...antenna section, 7a...inner conductor, 7b...outer conductor, 7c...through hole, 8...waveguide, 8a...first waveguide, 8b...second waveguide, 9...high frequency matching box, AR...area, MT...method, SH...shower section, T1...temperature sensor, T2...temperature sensor, TB...dielectric tube, W...wafer.

Claims

1. a) acquiring temperature information of a reaction chamber during plasma processing as information indicating a state of plasma density using at least one temperature detection element provided in an upper electrode of the plasma processing apparatus; b) converting the temperature information into power information, and adjusting the power supplied from a high frequency power source to the reaction chamber via the upper electrode based on the power information so as to reduce bias in plasma density distribution along the electrode surface of the upper electrode; Equipped with the upper electrode has a gap provided above and adjacent to the electrode surface exposed to the reaction chamber; the at least one temperature sensing element includes a first temperature sensing element positioned to measure a temperature at a bottom of the gap; Plasma treatment method.

2. the first temperature detection element is provided above a region including a peak of a plasma density distribution previously measured during plasma processing; The plasma processing method according to claim 1 .

3. the at least one temperature detection element includes a second temperature detection element spaced apart from the first temperature detection element; the second temperature detection element is provided above a flat region of the previously measured plasma density distribution; The plasma processing method according to claim 2 .

4. The temperature information acquired in the step a) is a difference obtained by subtracting a second temperature detected by the second temperature detection element from a first temperature detected by the first temperature detection element. The plasma processing method according to claim 3 .

5. the temperature information acquired in the step a) is a difference obtained by subtracting a first temperature detected by the first temperature detection element at a first timing from a second temperature detected by the first temperature detection element at a second timing after the first timing; The plasma processing method according to claim 1 .

6. A processing vessel configured to perform plasma processing; a mounting table provided in the processing chamber and configured to mount a wafer thereon; an upper electrode that is provided in the processing chamber and arranged above the mounting table so as to face the mounting table; a gas supply unit configured to supply a process gas to a reaction chamber between the upper electrode and the mounting table; a radio frequency power source electrically connected to the upper electrode and configured to generate a plasma of the process gas by supplying radio frequency power to the upper electrode; At least one temperature sensing element disposed within the upper electrode; a temperature information acquiring unit configured to acquire temperature information of the reaction chamber based on a temperature signal output from the at least one temperature detecting element; a power adjusting unit configured to convert the temperature information acquired by the temperature information acquiring unit into power information, and adjust the power supplied from the high frequency power source through the upper electrode to the reaction chamber based on the power information so as to reduce a bias in the plasma density distribution along the electrode surface of the upper electrode; Equipped with the upper electrode has a gap provided above and adjacent to the electrode surface exposed to the reaction chamber; the at least one temperature sensing element includes a first temperature sensing element positioned to measure a temperature at a bottom of the gap; Plasma processing equipment.

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