JP7333762B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

The present disclosure relates to a plasma processing apparatus and a plasma processing method.

2. Description of the Related Art A substrate processing apparatus is known that supplies a desired gas into a processing chamber and performs desired processing (eg, film formation processing) on a substrate placed on a mounting table provided in the processing chamber.

In Patent Document 1, a first gas shower section for supplying a first gas into the chamber and a second gas shower section for supplying a second gas into the chamber are provided. A plasma processing apparatus is disclosed in which the part has a plurality of nozzles equally spaced on the same circumference.

JP 2018-73880 A

In one aspect, the present disclosure provides a plasma processing apparatus and plasma processing method that improve in-plane uniformity of processing applied to a substrate.

In order to solve the above-described problems, according to one aspect, there is provided a processing container that accommodates a mounting table on which a substrate is placed, a gas supply unit that supplies gas to the processing container, and plasma that is generated in the processing container. a plasma generation unit that is provided on the ceiling wall of the processing container, the plasma generation unit has a plurality of antennas arranged in the circumferential direction of the ceiling wall, and has a plurality of antennas for irradiating microwaves; The supply unit includes a plurality of gas nozzles provided on a side wall of the processing container, arranged in a circumferential direction of the side wall , and ejecting gas in a horizontal direction , and a flow rate adjusting mechanism for adjusting flow rates of the plurality of gas nozzles. wherein, when the processing container is viewed in a vertical direction, the flow rate of the gas nozzles for ejecting gas toward the antennas is higher than the flow rate of the gas nozzles for ejecting gas toward between the antennas. be done.

According to one aspect, it is possible to provide a plasma processing apparatus and a plasma processing method that improve the in-plane uniformity of processing applied to a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS The cross-sectional schematic diagram which shows an example of the plasma processing apparatus which concerns on one Embodiment. FIG. 2 is an explanatory diagram showing the configuration of a control unit shown in FIG. 1; FIG. 2 is an explanatory diagram showing the configuration of the microwave introduction module shown in FIG. 1; Sectional drawing which shows the microwave introduction mechanism shown in FIG. FIG. 5 is a perspective view showing an antenna portion of the microwave introduction mechanism shown in FIG. 4; FIG. 5 is a plan view showing a planar antenna of the microwave introduction mechanism shown in FIG. 4; FIG. 2 is a bottom view of the ceiling wall of the processing container shown in FIG. 1; FIG. 2 is a horizontal cross-sectional view of the side wall of the processing container shown in FIG. 1; An example of a graph showing changes in the film thickness of the SiN film in the circumferential direction at the inner peripheral portion, intermediate portion, and outer peripheral portion of the substrate in the reference example. FIG. 4 is a schematic diagram showing an example of gas flow rate adjustment by a flow rate adjustment mechanism. 5 is a graph showing the film thickness of the SiN film formed on the outer peripheral portion of the substrate depending on the gas supply position; 5 is a graph showing the film thickness of a SiN film formed on a substrate depending on the gas supply position; The schematic diagram which shows an example of another flow regulating mechanism. The schematic diagram which shows an example of another flow control mechanism. 4 is a flowchart for explaining a gas flow rate adjustment method; The block diagram which shows an example of the content determination apparatus of adjustment.

Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant description may be omitted.

[Plasma processing equipment]
First, a schematic configuration of a plasma processing apparatus 1 according to an embodiment will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a cross-sectional schematic diagram showing an example of a plasma processing apparatus 1 according to one embodiment. FIG. 2 is an explanatory diagram showing an example of the configuration of the control unit 8 shown in FIG. 1. As shown in FIG. The plasma processing apparatus 1 according to the present embodiment performs a plurality of continuous operations on a substrate W, which is an example of a semiconductor wafer for manufacturing a semiconductor device, for film formation processing, diffusion processing, etching processing, and ashing processing. It is a device that performs predetermined processing such as. In the following description, the plasma processing apparatus 1 is a film forming apparatus that forms a SiN film on a substrate W by plasma CVD using a raw material gas containing Si and a nitriding gas.

The plasma processing apparatus 1 has a processing container 2 , a mounting table 21 , a gas supply mechanism 3 , an exhaust device 4 , a microwave introduction module 5 and a controller 8 . The processing container 2 accommodates substrates W, which are objects to be processed. The mounting table 21 is arranged inside the processing container 2 and has a mounting surface 21a on which the substrate W is mounted. The gas supply mechanism 3 supplies gas into the processing container 2 . The exhaust device 4 evacuates the inside of the processing container 2 under reduced pressure. The microwave introduction module 5 introduces microwaves for generating plasma in the processing container 2 . The controller 8 controls each part of the plasma processing apparatus 1 .

The processing container 2 has, for example, a substantially cylindrical shape. The processing container 2 is made of a metal material such as aluminum and its alloy. The microwave introduction module 5 is arranged above the processing container 2 and functions as a plasma generation unit that introduces electromagnetic waves (microwaves in this embodiment) into the processing container 2 to generate plasma.

The processing container 2 has a plate-like top wall 11 , a bottom wall 13 , and side walls 12 connecting the top wall 11 and the bottom wall 13 . The ceiling wall 11 has a plurality of openings. The side wall 12 has a loading/unloading port 12a for loading/unloading the substrate W to/from a transfer chamber (not shown) adjacent to the processing container 2 . A gate valve G is arranged between the processing container 2 and a transfer chamber (not shown). The gate valve G has a function of opening and closing the loading/unloading port 12a. The gate valve G airtightly seals the processing container 2 in a closed state, and enables transfer of the substrate W between the processing container 2 and a transfer chamber (not shown) in an open state.

The bottom wall 13 has a plurality of (two in FIG. 1) exhaust ports 13a. The plasma processing apparatus 1 further has an exhaust pipe 14 connecting the exhaust port 13 a and the exhaust device 4 . The evacuation device 4 has an APC valve and a high-speed vacuum pump capable of rapidly depressurizing the internal space of the processing container 2 to a predetermined degree of vacuum. Such high-speed vacuum pumps include, for example, turbomolecular pumps. By operating the high-speed vacuum pump of the exhaust device 4, the internal space of the processing container 2 is decompressed to a predetermined degree of vacuum, for example, 0.133 Pa.

The plasma processing apparatus 1 further includes a support member 22 that supports the mounting table 21 inside the processing chamber 2 and an insulating member 23 provided between the support member 22 and the bottom wall 13 . The mounting table 21 is for mounting the substrate W horizontally. The support member 22 has a cylindrical shape extending from the center of the bottom wall 13 toward the inner space of the processing container 2 . The mounting table 21 and the support member 22 are made of, for example, aluminum or the like whose surface is subjected to alumite treatment (anodization treatment).

The plasma processing apparatus 1 further includes a high-frequency bias power supply 25 that supplies high-frequency power to the mounting table 21 and a matching unit 24 provided between the mounting table 21 and the high-frequency bias power supply 25 . A high-frequency bias power supply 25 supplies high-frequency power to the mounting table 21 in order to attract ions to the substrate W. FIG. The matching device 24 has a circuit for matching the output impedance of the high-frequency bias power supply 25 and the impedance on the load side (the mounting table 21 side).

The plasma processing apparatus 1 may further have a temperature control mechanism (not shown) that heats or cools the mounting table 21 . The temperature control mechanism controls the temperature of the substrate W within a range of 25° C. (room temperature) to 900° C., for example.

The plasma processing apparatus 1 includes gas supply units 16 to 18 that supply gases into the processing container 2 .

The first gas supply section 16 has a gas introduction path 161 , a gas diffusion space 162 and a gas nozzle 163 . The gas introduction path 161 communicates with the gas diffusion space 162 and introduces the gas supplied from the gas supply mechanism 3 into the gas diffusion space 162 . The gas diffusion space 162 is annularly formed within the ceiling wall 11 . Note that the gas diffusion space 162 may be divided in the circumferential direction (see FIG. 7 described later). The gas introduced from the gas introduction path 161 diffuses within the gas diffusion space 162 . A plurality of gas nozzles 163 are connected to the gas diffusion space 162 . The gas nozzles 163 are arranged in the circumferential direction (see FIG. 7 to be described later) and protrude vertically from the lower surface of the ceiling wall 11 forming the processing container 2 . The gas nozzle 163 supplies (jets) gas vertically into the processing container 2 from a gas supply hole 164 formed at the tip thereof.

The second gas supply section 17 has a gas introduction path 171 , a gas diffusion space 172 and a gas nozzle 173 . The gas introduction path 171 communicates with the gas diffusion space 172 and introduces the gas supplied from the gas supply mechanism 3 into the gas diffusion space 172 . A gas diffusion space 172 is annularly formed within the sidewall 12 . Note that the gas diffusion space 172 may be divided in the circumferential direction (see FIG. 8 described later). The gas introduced from the gas introduction path 171 diffuses within the gas diffusion space 172 . A plurality of gas nozzles 173 are connected to the gas diffusion space 172 . The gas nozzles 173 are arranged in the circumferential direction (see FIG. 8 to be described later) and protrude horizontally from the inner wall surface of the side wall 12 forming the processing container 2 . The gas nozzle 173 supplies gas into the processing chamber 2 from a gas supply hole 174 formed at its tip. Here, the gas supply hole 174 of the second gas supply section 17 is provided radially outside of the processing container 2 with respect to the gas supply hole 164 of the first gas supply section 16 . Thereby, the gas nozzle 173 horizontally supplies (jets) the gas into the processing chamber 2 from the radially outer side of the gas nozzle 163 . supply.

The third gas supply section 18 has a gas introduction path 181 , a gas diffusion space 182 and a gas nozzle 183 . The gas introduction path 181 communicates with the gas diffusion space 182 and introduces the gas supplied from the gas supply mechanism 3 into the gas diffusion space 182 . The gas diffusion space 182 is annularly formed in the ceiling wall 11 (see FIG. 7 described later). Note that the gas diffusion space 182 may be divided in the circumferential direction. The gas introduced from the gas introduction path 181 diffuses within the gas diffusion space 182 . A plurality of gas nozzles 183 are connected to the gas diffusion space 182 . The gas nozzles 183 are arranged in the circumferential direction (see FIG. 7 to be described later) and protrude vertically from the lower surface of the ceiling wall 11 forming the processing container 2 . The gas nozzle 183 supplies gas into the processing container 2 from a gas supply hole 184 formed at its tip. Here, the gas supply hole 184 of the third gas supply section 18 is formed at a position higher than the gas supply hole 164 of the first gas supply section 16 and the gas supply hole 174 of the second gas supply section 17. ing. Thereby, the gas nozzle 183 supplies (jets) gas vertically into the processing chamber 2 from a position higher than the gas nozzle 163 .

The vertical direction in which the gas nozzles 163 and 183 eject gas also includes vertical directions in a broader sense, such as slightly inward or outward directions. Further, the horizontal direction in which the gas nozzle 173 ejects gas also includes a horizontal direction in a broad sense such as slightly upward or downward from the horizontal.

Further, the gas supply units 16 to 18 each have a flow rate adjusting mechanism for adjusting the gas flow rate to be supplied into the processing container 2 for each of the gas nozzles 163, 173, and 183. FIG. Here, each gas nozzle 163, 173, 183 is configured to be replaceable as a flow rate adjusting mechanism. Accordingly, by replacing the gas nozzles with different nozzle diameters and different nozzle conductances, the flow rates of the gases supplied from the gas nozzles 163, 173, and 183 into the processing chamber 2 can be individually adjusted.

The gas supply source 31 is used as a gas supply source for, for example, a rare gas for plasma generation, or a gas used for oxidation, nitridation, film formation, etching, and ashing. For example, a gas that is difficult to decompose is supplied from the gas nozzle 183 of the third gas supply unit 18 into the processing container 2, and a gas that is easy to decompose is supplied from the gas nozzle 163 of the first gas supply unit 16 and the gas nozzle 163 of the second gas supply unit 17. It is supplied into the processing container 2 from the gas nozzle 173 . For example, among the N ₂ gas and silane gas used when forming a SiN film, the N ₂ gas that is difficult to decompose is introduced from the gas nozzle 183 , and the silane gas that is easy to decompose is introduced from the gas nozzles 163 and 173 . As a result, a good quality SiN film can be formed by preventing excessive dissociation of the easily decomposable silane gas.

The gas supply mechanism 3 includes a gas supply device 3 a including a gas supply source 31 , a pipe 32 a connecting the gas supply source 31 and the first gas supply section 16 , a gas supply source 31 and the second gas supply section 17 . and a pipe 32c that connects the gas supply source 31 and the third gas supply unit 18 . Although one gas supply source 31 is illustrated in FIG. 1, the gas supply device 3a may include a plurality of gas supply sources depending on the type of gas used.

The gas supply device 3a further includes a mass flow controller and an opening/closing valve (not shown) provided in the middle of the pipes 32a to 32c. The types of gases supplied into the processing container 2, the flow rates of these gases, and the like are controlled by a mass flow controller and an on-off valve.

Each component of the plasma processing apparatus 1 is connected to the controller 8 and controlled by the controller 8 . Control unit 8 is typically a computer. In the example shown in FIG. 2, the control unit 8 has a process controller 81 having a CPU, a user interface 82 connected to the process controller 81, and a storage unit 83.

The process controller 81 is control means for centrally controlling each component related to process conditions such as temperature, pressure, gas flow rate, high-frequency power for bias application, and microwave output in the plasma processing apparatus 1 . Each component includes, for example, a high-frequency bias power source 25, a gas supply device 3a, an exhaust device 4, a microwave introduction module 5, and the like.

The user interface 82 has a keyboard and a touch panel for inputting commands for the process manager to manage the plasma processing apparatus 1, a display for visualizing and displaying the operation status of the plasma processing apparatus 1, and the like.

The storage unit 83 stores a control program for realizing various processes executed by the plasma processing apparatus 1 under the control of the process controller 81, recipes in which process condition data and the like are recorded. The process controller 81 calls up an arbitrary control program or recipe from the storage unit 83 as required, such as an instruction from the user interface 82, and executes it. Thereby, desired processing is performed in the processing chamber 2 of the plasma processing apparatus 1 under the control of the process controller 81 .

The control program and recipe described above can be used in a state of being stored in a computer-readable storage medium such as flash memory, DVD, and Blu-ray disc. Also, the above recipe can be transmitted from another device, for example, via a dedicated line as needed and used online.

Next, the configuration of the microwave introduction module 5 will be described with reference to FIGS. 1 to 6. FIG. FIG. 3 is an explanatory diagram showing the configuration of the microwave introduction module shown in FIG. FIG. 4 is a cross-sectional view showing the microwave introduction mechanism 63 shown in FIG. FIG. 5 is a perspective view showing the antenna section of the microwave introduction mechanism 63 shown in FIG. FIG. 6 is a plan view showing the planar antenna of the microwave introduction mechanism 63 shown in FIG.

The microwave introduction module 5 is provided above the processing container 2 and introduces electromagnetic waves (microwaves) into the processing container 2 . As shown in FIG. 1 , the microwave introduction module 5 has a ceiling wall 11 that is a conductive member, a microwave output section 50 and an antenna unit 60 . The ceiling wall 11 is arranged above the processing container 2 and has a plurality of openings. The microwave output unit 50 generates microwaves, distributes the microwaves to a plurality of paths, and outputs the microwaves. The antenna unit 60 introduces the microwave output from the microwave output unit 50 into the processing container 2 . In this embodiment, the ceiling wall 11 of the processing vessel 2 also serves as a conductive member of the microwave introduction module 5 .

As shown in FIG. 3, the microwave output unit 50 includes a power supply unit 51, a microwave oscillator 52, an amplifier 53 that amplifies the microwaves oscillated by the microwave oscillator 52, and the microwaves amplified by the amplifier 53. and a distributor 54 for distributing to a plurality of routes. The microwave oscillator 52 oscillates microwaves at a predetermined frequency (2.45 GHz, for example). Note that the frequency of the microwave is not limited to 2.45 GHz, and may be 8.35 GHz, 5.8 GHz, 1.98 GHz, or the like. Moreover, such a microwave output unit 50 can be applied to a case where the frequency of the microwave is within the range of 800 MHz to 1 GHz, such as 860 MHz. The distributor 54 distributes the microwave while matching the impedance on the input side and the output side.

Antenna unit 60 includes a plurality of antenna modules 61 . The plurality of antenna modules 61 each introduces the microwaves distributed by the distributor 54 into the processing container 2 . In this embodiment, all of the multiple antenna modules 61 have the same configuration. Each antenna module 61 has an amplifier section 62 that mainly amplifies and outputs distributed microwaves, and a microwave introduction mechanism 63 that introduces the microwaves output from the amplifier section 62 into the processing container 2 . ing.

The amplifier section 62 has a phase shifter 62A, a variable gain amplifier 62B, a main amplifier 62C and an isolator 62D. A phase shifter 62A changes the phase of the microwave. The variable gain amplifier 62B adjusts the power level of the microwave input to the main amplifier 62C. The main amplifier 62C is configured as a solid state amplifier. The isolator 62D separates reflected microwaves that are reflected by the antenna section of the microwave introduction mechanism 63 and head toward the main amplifier 62C.

The phase shifter 62A changes the phase of the microwaves to change the radiation characteristics of the microwaves. The phase shifter 62A is used, for example, to adjust the phase of the microwave for each antenna module 61 to control the directivity of the microwave and change the plasma distribution. It should be noted that the phase shifter 62A may not be provided if such adjustment of radiation characteristics is not performed.

The variable gain amplifier 62B is used for adjusting variations in individual antenna modules 61 and adjusting plasma intensity. For example, by changing the variable gain amplifier 62B for each antenna module 61, the plasma distribution in the entire processing container 2 can be adjusted.

The main amplifier 62C includes, for example, an input matching circuit, a semiconductor amplifying element, an output matching circuit, and a high Q resonance circuit (not shown). As the semiconductor amplifying element, for example, GaAsHEMT, GaNHEMT, and LD (laterally diffused)-MOS capable of class E operation are used.

The isolator 62D has a circulator and a dummy load (coaxial terminator). The circulator guides the reflected microwave reflected by the antenna section of the microwave introduction mechanism 63 to the dummy load. The dummy load converts the reflected microwaves guided by the circulator into heat. As described above, in this embodiment, a plurality of antenna modules 61 are provided, and a plurality of microwaves introduced into the processing container 2 by the microwave introducing mechanisms 63 of the plurality of antenna modules 61 are , are synthesized in the processing container 2 . Therefore, each isolator 62D may be small, and the isolator 62D may be provided adjacent to the main amplifier 62C.

As shown in FIG. 1 , a plurality of microwave introducing mechanisms 63 are provided on the ceiling wall 11 . As shown in FIG. 4 , the microwave introduction mechanism 63 has a tuner 64 for impedance matching and an antenna section 65 for radiating amplified microwaves into the processing container 2 . Further, the microwave introduction mechanism 63 is made of a metal material, and includes a main body container 66 having a cylindrical shape extending in the vertical direction in FIG. 67. The main container 66 and the inner conductor 67 constitute a coaxial tube. The main container 66 constitutes the outer conductor of this coaxial waveguide. The inner conductor 67 has a rod-like or tubular shape. A space between the inner peripheral surface of the main container 66 and the outer peripheral surface of the inner conductor 67 forms a microwave transmission path 68 .

The antenna module 61 further has a feeding converter provided on the base end side (upper end side) of the main body container 66 (not shown). The feed converter is connected to the main amplifier 62C via a coaxial cable. The isolator 62D is provided in the middle of the coaxial cable. The antenna section 65 is provided on the opposite side of the main container 66 to the power conversion section. As will be described later, a portion of the main body container 66 closer to the proximal side than the antenna portion 65 is an impedance adjustment range of the tuner 64 .

As shown in FIGS. 4 and 5, the antenna section 65 includes a planar antenna 71 connected to the lower end of the inner conductor 67, a microwave slow wave material 72 disposed on the upper surface side of the planar antenna 71, and a planar and a microwave transmission plate 73 arranged on the lower surface side of the antenna 71 . A lower surface of the microwave transmission plate 73 is exposed to the inner space of the processing container 2 . The microwave transmission plate 73 is fitted into the opening of the top wall 11 , which is a conductive member of the microwave introduction module 5 , through the main container 66 . The microwave transmission plate 73 corresponds to the microwave transmission window in this embodiment.

The planar antenna 71 has a disk shape. Moreover, the planar antenna 71 has a slot 71a formed so as to penetrate the planar antenna 71 . In the example shown in FIGS. 5 and 6, four slots 71a are provided, and each slot 71a has an arc shape divided evenly into four. The number of slots 71a is not limited to four, and may be five or more, or may be one or more and three or less.

The microwave slow wave material 72 is made of a material having a dielectric constant greater than that of vacuum. As a material for forming the microwave slow wave material 72, for example, quartz, ceramics, fluorine-based resin such as polytetrafluoroethylene resin, polyimide resin, or the like can be used. Microwaves have longer wavelengths in a vacuum. The microwave slow wave material 72 has the function of adjusting the plasma by shortening the wavelength of the microwave. Also, the phase of the microwave changes depending on the thickness of the microwave slow wave material 72 . Therefore, by adjusting the phase of the microwave by adjusting the thickness of the microwave slow wave material 72, the planar antenna 71 can be adjusted to the position of the antinode of the standing wave. As a result, reflected waves in the planar antenna 71 can be suppressed, and the radiant energy of microwaves radiated from the planar antenna 71 can be increased. That is, thereby, the power of the microwave can be efficiently introduced into the processing container 2 .

The microwave transmission plate 73 is made of a dielectric material. As a dielectric material forming the microwave transmission plate 73, for example, quartz, ceramics, or the like is used. The microwave transmission plate 73 has a shape that can efficiently radiate microwaves in the TE mode. In the example of FIG. 5, the microwave transmission plate 73 has a rectangular parallelepiped shape. The shape of the microwave transmitting plate 73 is not limited to a rectangular parallelepiped shape, and may be, for example, a columnar shape, a pentagonal columnar shape, a hexagonal columnar shape, or an octagonal columnar shape.

In the microwave introduction mechanism 63 having such a configuration, the microwave amplified by the main amplifier 62C passes through the microwave transmission path 68 between the inner peripheral surface of the main container 66 and the outer peripheral surface of the inner conductor 67, and reaches the planar antenna 71. reach. Then, the microwaves are transmitted through the slot 71 a of the flat antenna 71 through the microwave transmitting plate 73 and radiated into the inner space of the processing vessel 2 .

Tuner 64 constitutes a slug tuner. Specifically, as shown in FIG. 4, the tuner 64 has two slugs 74A and 74B that are arranged on the base end side (upper end side) of the main container 66 relative to the antenna portion 65. . Further, the tuner 64 has an actuator 75 for operating the two slugs 74A, 74B and a tuner controller 76 for controlling this actuator 75. As shown in FIG.

The slugs 74A and 74B have plate-like and annular shapes and are arranged between the inner peripheral surface of the main container 66 and the outer peripheral surface of the inner conductor 67 . Also, the slugs 74A and 74B are made of a dielectric material. As a dielectric material forming the slugs 74A and 74B, for example, high-purity alumina having a dielectric constant of 10 can be used. High-purity alumina has a higher dielectric constant than quartz (relative dielectric constant 3.88) and Teflon (registered trademark) (relative dielectric constant 2.03), which are usually used as materials for forming slag. The thickness of 74A and 74B can be reduced. In addition, high-purity alumina has a smaller dielectric loss tangent (tan δ) than quartz or Teflon (registered trademark), and has the characteristic of being able to reduce the loss of microwaves. High-purity alumina also has the characteristics of low distortion and high heat resistance. The high-purity alumina is preferably an alumina sintered body with a purity of 99.9% or higher. Single crystal alumina (sapphire) may also be used as high-purity alumina.

The tuner 64 vertically moves the slugs 74A and 74B with an actuator 75 based on a command from the tuner controller 76 . Thereby, the tuner 64 adjusts the impedance. For example, the tuner controller 76 adjusts the positions of the slugs 74A, 74B so that the impedance of the termination portion is, for example, 50Ω.

In this embodiment, the main amplifier 62C, the tuner 64 and the planar antenna 71 are arranged close to each other. In particular, tuner 64 and planar antenna 71 constitute a lumped constant circuit and function as a resonator. An impedance mismatch exists in the mounting portion of the planar antenna 71 . In this embodiment, the tuner 64 can tune, including the plasma, with high accuracy, and the influence of reflection in the planar antenna 71 can be eliminated. Also, the tuner 64 can eliminate the impedance mismatch up to the planar antenna 71 with high accuracy, and the mismatched portion can be substantially made into a plasma space. This allows the tuner 64 to control the plasma with high accuracy.

Next, the bottom surface of the ceiling wall 11 of the processing container 2 shown in FIG. 1 will be described with reference to FIG. FIG. 7 is a diagram showing an example of the bottom surface of the ceiling wall 11 of the processing container 2 shown in FIG. In the following description, it is assumed that the microwave transmission plate 73 has a cylindrical shape.

The microwave introduction module 5 includes a plurality of microwave transmission plates 73 . As described above, the microwave transparent plate 73 corresponds to the microwave transparent window. The plurality of microwave transmission plates 73 are fitted in the plurality of openings of the ceiling wall 11, which is the conductive member of the microwave introduction module 5, and form one imaginary plate parallel to the mounting surface 21a of the mounting table 21. placed on a plane. Also, the plurality of microwave transmission plates 73 includes three microwave transmission plates 73 having equal or substantially equal distances between their center points on the virtual plane. The fact that the distances between the center points are almost equal means that the position of the microwave transmitting plate 73 is It means that it may be slightly deviated from the desired position.

In this embodiment, the plurality of microwave permeable plates 73 are composed of seven microwave permeable plates 73 arranged in a hexagonal close-packed arrangement. Specifically, the plurality of microwave transmission plates 73 has seven microwave transmission plates 73A to 73G. The six microwave transmitting plates 73A to 73F among them are arranged so that their center points coincide or nearly coincide with the vertices of the regular hexagon. One microwave transmission plate 73G is arranged so that its center point coincides or nearly coincides with the center of the regular hexagon. It should be noted that the phrase “substantially coincides with the vertex or center point” means that the center point of the microwave permeable plate 73 is the vertex from the viewpoint of the shape accuracy of the microwave permeable plate 73 and the assembly accuracy of the antenna module 61 (microwave introduction mechanism 63). Or it means that it may be slightly off-center.

As shown in FIG. 7, the microwave transmission plate 73G is arranged in the central portion of the ceiling wall 11. As shown in FIG. The six microwave transmission plates 73A to 73F are arranged outside the central portion of the ceiling wall 11 so as to surround the microwave transmission plate 73G. Accordingly, the microwave-transmissive plate 73G corresponds to the central microwave-transmissive window, and the microwave-transmissive plates 73A-73F correspond to the outer microwave-transmissive windows. In addition, in this embodiment, "the center part in the top wall 11" means "the center part in the planar shape of the top wall 11."

In this embodiment, the distances between the center points of arbitrary three microwave transmitting plates 73 adjacent to each other are equal or substantially equal to each other in all the microwave transmitting plates 73 . The gas nozzles 163 and 183 are circumferentially arranged between the outer microwave transparent plates 73A-73G and the central microwave transparent plate 73G.

Here, as shown in the arrangement of the microwave transmission plates 73A to 73G, the microwave introduction mechanism 63 has one antenna portion 65 in the center (see the microwave transmission plate 73G) and six in the outer peripheral portion (microwave transmission plates 73A to 73G). See plates 73A-73F) are arranged. Therefore, the arrangement of the antenna portion 65 of the microwave introduction mechanism 63 has six-fold symmetry in the circumferential direction.

Also, FIG. 7 shows the first gas supply section 16 and the third gas supply section 18 . In FIG. 7, the gas introduction path 161, the gas diffusion space 162, the gas introduction path 181, and the gas diffusion space 182 formed in the ceiling wall 11 are indicated by hidden lines (broken lines).

In the example shown in FIG. 7, a total of 12 gas nozzles 163 are arranged at equal intervals in the circumferential direction on the back surface of the ceiling wall 11 . Here, the gas diffusion space 162 is divided into three in the circumferential direction. Four gas nozzles 163 are provided for one arc-shaped gas diffusion space 162 . Therefore, the arrangement of the flow path structure of the first gas supply section 16 has three-fold symmetry in the circumferential direction. For the gas supply from the gas supply source 31 to each gas introduction passage 161, a mass flow controller (not shown) is provided for each divided gas diffusion space 162. It may be configured so that the flow rate of gas supplied to can be individually adjusted. Further, the gas supply from the gas supply source 31 to each gas introduction path 161 is configured such that the gas whose flow rate is controlled by one mass flow controller (not shown) is branched and supplied to each gas introduction path 161. good too.

A total of 12 gas nozzles 183 are arranged at equal intervals in the circumferential direction on the back surface of the ceiling wall 11 . It should be noted that the gas diffusion space 182 is not divided in the circumferential direction and is formed in an annular shape. Twelve gas nozzles 183 are provided for the annular gas diffusion space 182 . Three gas introduction paths 181 are provided for the gas diffusion space 182 . A mass flow controller (not shown) is provided for each gas introduction path 181 to supply gas from the gas supply source 31 to each gas introduction path 181 . It may be configured such that the gas flow rate to be applied can be individually adjusted. Further, the gas supply from the gas supply source 31 to each gas introduction path 181 is configured such that the gas whose flow rate is controlled by one mass flow controller (not shown) is branched and supplied to each gas introduction path 181. good too.

FIG. 8 is a diagram showing an example of a horizontal cross section of the side wall 12 of the processing container 2 shown in FIG. In the example shown in FIG. 8, a total of 30 gas nozzles 173 are arranged at equal intervals in the circumferential direction on the inner wall surface of the side wall 12 . Here, the gas diffusion space 172 is divided into six in the circumferential direction. Five gas nozzles 173 are provided for one arc-shaped gas diffusion space 172 . Therefore, the arrangement of the channel structure of the second gas supply section 17 has 6-fold symmetry in the circumferential direction. A mass flow controller (not shown) is provided for each divided gas diffusion space 172 to supply gas from the gas supply source 31 to each gas introduction passage 171 . It may be configured so that the flow rate of gas supplied to can be individually adjusted. Further, the gas supply from the gas supply source 31 to each gas introduction path 171 is configured such that the gas whose flow rate is controlled by one mass flow controller (not shown) is branched and supplied to each gas introduction path 171. good too.

FIG. 9 is an example of a graph showing changes in film thickness of the SiN film in the circumferential direction at the inner peripheral portion, intermediate portion, and outer peripheral portion of the substrate W in the reference example. Here, as a reference example, it is assumed that a SiN film is formed on the substrate W using the plasma processing apparatus 1 assuming that the conductances of a plurality of gas nozzles arranged in the circumferential direction are equal. In FIG. 9, the horizontal axis indicates the circumferential angle of the substrate W, and the vertical axis indicates the film thickness. In addition, for the substrate W with a radius of 150 mm, the film thickness variation in the inner peripheral portion (on the circumference of the radius R = 49 mm), the thickness variation in the intermediate portion (on the circumference of the radius R = 98 mm), and the outer peripheral portion (on the circumference of the radius R = 98 mm) R=147 mm on the circumference).

As shown in FIG. 9, in the peripheral portion of the substrate W, six periodic film thickness fluctuations appear. This is because the arrangement of the antenna part 65 of the microwave introduction mechanism 63 has six-fold symmetry in the circumferential direction, so that the plasma generated by the microwave introduction module 5 is also non-uniform in the circumferential direction. , and the film thickness of the SiN film formed on the substrate W also becomes uneven.

On the other hand, the plasma processing apparatus 1 according to this embodiment has a flow rate adjusting mechanism for adjusting the flow rate of the gas supplied into the processing chamber 2 for each of the gas nozzles 163 , 173 and 183 .

FIG. 10 is a schematic diagram showing an example of gas flow rate adjustment by a flow rate adjustment mechanism. In the substrate W, thicker regions 901 and thinner regions 902 are arranged alternately in the circumferential direction. In the example shown in FIG. 10, in the second gas supply unit 17, the flow rate of the gas directed to the thick film region 901 is reduced (indicated by the black arrow in FIG. Increase the flow rate of the onward gas (indicated by the white arrow in FIG. 10). That is, in the example of FIG. 10, gas nozzles with small conductance are used for the gas nozzles 173A and 173E, and gas nozzles with large conductance are used for the gas nozzle 173C. That is, the flow rate of gas supplied from the gas nozzles 173A to 173E into the processing container 2 may be made non-uniform.

By adjusting the flow rate of the gas supplied from the gas nozzles 173A to 173E into the processing container 2, the film thickness variation can be suppressed with respect to the film thickness variation caused by the arrangement of the antenna portion 65 of the microwave introduction mechanism 63. Suppress. Thereby, the uniformity of the film thickness of the SiN film formed on the substrate W in the circumferential direction can be improved. That is, by adjusting the combination of the conductance of the gas nozzles 173 arranged in the circumferential direction in the second gas supply unit 17, the uniformity in the circumferential direction of the film thickness of the SiN film formed on the substrate W can be improved. can be done.

For example, on the outer peripheral side of the substrate W, a region 902 where the film thickness is thin is formed below the outer microwave transmitting plates 73A to 73F, and below between the microwave transmitting plates 73A to 73F adjacent in the circumferential direction. A region 901 where the film thickness is thick is formed. When the processing container 2 is viewed in the vertical direction, the flow rate of the gas nozzle 173C for ejecting gas toward the antenna portion 65 (outer microwave transmission plates 73A to 73F) of the outer microwave introduction mechanism 63 is determined by the outer microwave introduction. The flow rate is made larger than that of the gas nozzles 173A and 173E that eject gas toward the space between the antenna portions 65 of the mechanism 63 . Thereby, the uniformity of the film thickness of the SiN film formed on the substrate W in the circumferential direction can be improved.

More specifically, the gas nozzles 173 are provided at equal intervals along the side wall 12 of the substantially cylindrical processing container 2, and the gas jetting direction of each gas nozzle 173 is toward the center of the substrate W. direction. When the mounting table 21 is viewed from above the processing container 2 (projected onto a plane parallel to the substrate W), the gas ejection amount of the gas nozzle 173 where any one of the outer microwave transmission plates 73A to 73F exists in the gas ejection direction. is larger than the gas ejection amount of the gas nozzle 173 without the outer microwave transmitting plates 73A to 73F in the gas ejection direction. With such a configuration, the flow rate of the gas supplied below the outer microwave permeable plates 73A to 73F (area 902 where the film thickness is thin) is adjusted to the lower portion between the outer microwave permeable plates 73A to 73F ( The flow rate of the gas supplied to the region 901 where the film thickness is thickened can be increased. Thereby, the uniformity of the film thickness of the SiN film formed on the substrate W in the circumferential direction can be improved.

FIG. 11 is an example of a graph showing the film thickness of the SiN film formed on the outer periphery of the substrate W depending on the gas supply position. The horizontal axis indicates the circumferential angle, and the vertical axis indicates the normalized film thickness. A graph 801 shows the case where a film is formed by supplying gas from the second gas supply unit 17 . A graph 802 shows the case where the film is formed by supplying the gas from the first gas supply unit 16 . A graph 803 shows the case where the film is formed by supplying gas from both the first gas supply unit 16 and the second gas supply unit 17 .

FIG. 12 is a graph showing the film thickness of the SiN film formed on the substrate W depending on the gas supply position. The horizontal axis indicates the distance (radial distance) from the center of the substrate W, and the vertical axis indicates the film thickness. A graph 804 shows the case where the film is formed by supplying the gas from the second gas supply unit 17 . A graph 805 shows the case where the film is formed by supplying the gas from the first gas supply unit 16 . A graph 806 shows the case where the film is formed by supplying gas from both the first gas supply section 16 and the second gas supply section 17 .

As shown in FIG. 11, by supplying the gas from the first gas supply section 16 and the second gas supply section 17, it is possible to reduce unevenness in film thickness in the circumferential direction. Here, in the range/average value ((maximum value−minimum value)/average value), which is an index of uniformity, the graph 803 shows an improvement of 60 to 70% compared to the graphs 801 and 802 . In addition, as shown in FIG. 12, by supplying gases from the first gas supply unit 16 and the second gas supply unit 17, it is possible to reduce unevenness in film thickness in the radial direction.

That is, the combination of the conductance of the gas nozzles 173 arranged in the circumferential direction in the second gas supply section 17 and the conductance combination of the gas nozzles 163 arranged in the circumferential direction in the first gas supply section 16 are adjusted. By doing so, the uniformity of the film thickness of the SiN film formed on the substrate W can be improved in the circumferential and radial directions.

<Other flow control mechanisms>
Although the gas nozzles 163, 173, and 183 are configured to be replaceable as the flow rate adjusting mechanism, the flow rate adjusting mechanism is not limited to this.

FIG. 13 is a schematic diagram showing an example of another flow rate adjustment mechanism. As shown in FIG. 13 , in the first gas supply section 16 , a flow rate adjusting mechanism 165 such as a variable orifice may be provided between the gas diffusion space 162 and the gas nozzle 163 . Although not shown, a flow rate adjusting mechanism such as a variable orifice may be provided between the gas diffusion space 172 and the gas nozzle 173 in the second gas supply section 17 .

FIG. 14 is a schematic diagram showing an example of still another flow control mechanism. As shown in FIG. 14, in the first gas supply section 16, a gas diffusion space 162 may be provided with a flow rate adjusting mechanism 166 such as a variable orifice. Although not shown, in the second gas supply section 17, the gas diffusion space 172 may be provided with a flow rate adjusting mechanism such as a variable orifice.

<How to adjust the gas flow rate of the flow rate adjusting mechanism>
Next, the gas flow rate adjusting method of the flow rate adjusting mechanism will be described with reference to FIG. 15 . FIG. 15 is a flow chart for explaining the gas flow rate adjustment method.

In step S<b>101 , the substrate W is subjected to plasma processing using the plasma processing apparatus 1 . Here, a SiN film is formed on the substrate W based on process conditions. Information on the process conditions of plasma processing includes gas species (process gas, excitation gas, etc.), gas flow rate from the gas supply source 31 to each gas diffusion space 162, 172, 182 by a mass flow controller, pressure, temperature (substrate temperature, process wall temperature of the container 2), plasma power (microwave output at each antenna unit 60). Further, the nozzle diameter and nozzle conductance of each gas nozzle 163, 173, 183 are included as the information of the flow rate adjusting mechanism in the plasma processing apparatus 1 when the plasma processing is performed. Design values can be used for the nozzle diameters of the gas nozzles 163 , 173 , and 183 . Also, the conductance of each gas nozzle 163, 173, 183 is measured in advance. When the flow rate adjusting mechanism is the flow rate adjusting mechanism 165 such as the variable orifice shown in FIG. 13 or 14, the information of the flow rate adjusting mechanism includes the orifice diameter of each variable orifice.

In step S102, the process result of the plasma treatment in step S101 is measured. Here, the film thickness and/or the refractive index of the SiN film formed on the substrate W are measured as the process results. A plurality of measurement points are provided in the circumferential direction and the radial direction of the substrate W. As shown in FIG. For example, a plurality of measurement points may be provided on a plurality of circles concentric with the substrate W and having different diameters.

In step S103, the adjustment details of the flow rate adjustment mechanism are determined based on the process conditions of the plasma processing and information on the flow rate adjustment mechanism in step S101 and the process result in step S102.

FIG. 16 is a block diagram showing an example of the adjustment content determination device 500. As shown in FIG. The adjustment content determination device 500 is, for example, a computer server or the like. Adjustment content determination device 500 includes input unit 501 , analysis unit 502 , and output unit 503 .

The input unit 501 receives, as input information, the process conditions of the plasma treatment in step S101 and information on the flow rate adjusting mechanism, and the process result in step S102.

The analysis unit 502 performs analysis based on the input information input by the input unit 501 and outputs output information. The output information includes information on the process conditions of plasma processing and the flow control mechanism.

The analysis unit 502 determines the output information so that the film thickness is uniformed and/or the refractive index is uniformed. Specifically, the analysis unit 502 determines the output information so that the process result (film thickness and/or refractive index) of the substrate W in the circumferential direction is uniform.

The analysis unit 502 may be configured to determine output information based on, for example, design of experiments.

Further, the analysis unit 502 may be configured to determine output information based on machine learning, for example. That is, the analysis unit 502 generates a learned model by machine learning in advance using the process conditions of the plasma treatment and the information of the flow rate adjustment mechanism as input data and the process results of the plasma treatment as output data. The analysis unit 502 determines output information based on the input information and the trained model.

Note that the analysis unit 502 may directly derive the output information based on the input information. Further, the analysis unit 502 may derive intermediate output information based on the input information and calculate output information based on the intermediate output information. Here, the sensitivity coefficient (contribution) of the gas nozzle (nozzle diameter, conductance) at the measurement point of the substrate W may be used as the intermediate output information. Here, if the number of measurement points is A and the number of gas nozzles is B, A×B sensitivity coefficients are determined. Also, if there is an interaction between nozzles, A× _B C ₂ sensitivity coefficients are determined. If the flow rate adjustment mechanism is a flow rate adjustment mechanism 165 such as a variable orifice shown in FIG. 13 or 14, the intermediate output information may be the sensitivity coefficient (contribution) of each flow rate adjustment mechanism 165 (variable orifice). .

The output unit 503 outputs output information. The output information of the adjustment content determination device 500 is used in step S104. Also, the output unit 503 may output intermediate output information. Intermediate output information from the adjustment content determination device 500 can be used for physical examination, fault determination, and the like.

Returning to FIG. 15, in step S104, the gas flow rate is adjusted by adjusting the flow rate adjusting mechanism based on the result of step S103. Here, each gas nozzle 163, 173, 183 is exchanged so that the nozzle diameter and nozzle conductance of each gas nozzle 163, 173, 183 obtained in step S103 are obtained. When the flow rate adjusting mechanism is the flow rate adjusting mechanism 165 such as the variable orifice shown in FIG. 13 or 14, the orifice diameter of each flow rate adjusting mechanism 165 is adjusted.

The plasma processing apparatus 1 according to one embodiment disclosed this time should be considered as an example and not restrictive in all respects. The embodiments described above can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The items described in the above multiple embodiments can take other configurations within a consistent range, and can be combined within a consistent range.

Although the gas diffusion space 162 has been described as being formed by dividing the gas diffusion space 162 in the circumferential direction, the first gas supply part 16 is not limited to this, and may be formed in an annular shape. Similarly, the second gas supply section 17 has been described as being formed by dividing the gas diffusion space 172 in the circumferential direction. In addition, although the gas diffusion space 182 of the third gas supply unit 18 has been described as being formed in an annular shape, it is not limited to this, and may be formed by being divided in the circumferential direction.

W Substrate 1 Plasma processing apparatus 2 Processing container 21 Mounting table 3 Gas supply mechanism 4 Exhaust device 5 Microwave introduction module (plasma generation unit)
8 control section 16 gas supply section 161 gas introduction path 162 gas diffusion space 163 gas nozzle 164 gas supply hole 17 gas supply section 171 gas introduction path 172 gas diffusion space 173 gas nozzle 174 gas supply hole 18 gas supply section 181 gas introduction path 182 gas diffusion Space 183 Gas nozzle 184 Gas supply hole 500 Adjustment content determination device 501 Input section 502 Analysis section 503 Output section

Claims (11)

a processing container accommodating a mounting table on which the substrate is mounted;
a gas supply unit that supplies gas to the processing container;
a plasma generator that generates plasma in the processing container,
The plasma generation unit is
A plurality of antennas provided on the ceiling wall of the processing container, arranged in a plurality in the circumferential direction of the ceiling wall, and irradiating microwaves,
The gas supply unit
a plurality of gas nozzles provided on a side wall of the processing container, arranged in a plurality in the circumferential direction of the side wall , and ejecting gas in a horizontal direction ;
a flow rate adjustment mechanism that adjusts the flow rates of the plurality of gas nozzles ,
When the processing container is viewed in the vertical direction, the flow rate of the gas nozzle that ejects gas toward the antenna is greater than the flow rate of the gas nozzle that ejects gas toward between the antennas.
Plasma processing equipment. The gas supply unit
having a gas diffusion space annularly arranged on the wall of the processing container and connected to the gas nozzle;
The plasma processing apparatus according to claim 1 . the gas diffusion space is divided in the circumferential direction,
The plasma processing apparatus according to claim 2 . The flow rate adjustment mechanism is configured such that the gas nozzle can be replaced,
The plasma processing apparatus according to any one of claims 1 to 3 . The flow rate adjustment mechanism is an orifice provided in a communication portion between the gas diffusion space and the gas nozzle,
4. The plasma processing apparatus according to claim 2 or 3 . The flow rate adjustment mechanism is an orifice provided in the gas diffusion space,
4. The plasma processing apparatus according to claim 2 or 3 . A processing container that accommodates a mounting table on which a substrate is placed, a gas supply unit that supplies gas to the processing container, and a plasma generating unit that generates plasma in the processing container, the plasma generating unit comprising: provided on the ceiling wall of the processing container, and having a plurality of antennas arranged in a circumferential direction of the ceiling wall for irradiating microwaves ; A plasma processing method for a plasma processing apparatus, comprising : a plurality of gas nozzles arranged in the circumferential direction of the nozzle for ejecting gas in the horizontal direction ;
adjusting the flow rate adjustment mechanism;
supplying the gas from the adjusted gas supply unit to the processing container to perform plasma processing on the substrate ;
The step of adjusting the flow rate adjustment mechanism includes:
When the processing container is viewed in the vertical direction, the flow rate of the gas nozzle that ejects gas toward the antenna is adjusted to be greater than the flow rate of the gas nozzle that ejects gas toward between the antennas.
Plasma treatment method. The step of adjusting the flow rate adjustment mechanism includes exchanging the gas nozzle.
The plasma processing method according to claim 7 . The step of adjusting the flow rate adjusting mechanism includes adjusting an orifice diameter of an orifice provided in a communication portion between the gas diffusion space and the gas nozzle.
The plasma processing method according to claim 7 . The step of adjusting the flow rate adjustment mechanism adjusts an orifice diameter of an orifice provided in the gas diffusion space.
The plasma processing method according to claim 7 . The plasma treatment is a film formation treatment,
The plasma processing method according to any one of claims 7 to 10 .

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