Plasma processing apparatus and plasma processing method

Abstract

The present invention provides a technology that prevents plasma processing failure in the vicinity of an outer periphery of a substrate to be processed. The present invention provides a technology characterized by comprising: a processing chamber in which a substrate to be processed is subjected to plasma processing; a high-frequency power supply that supplies microwave power via a waveguide; a dielectric plate that is disposed above the processing chamber and through which the microwave transmits; a sample stage on which the substrate to be processed is placed; an electromagnet that is disposed so as to surround the periphery of the processing chamber and that generates a first static magnetic field; a static magnetic field generation device that is disposed below the substrate to be processed; and a control device that controls the electromagnet. The technology is also characterized in that: the static magnetic field generation device generates a second static magnetic field in a direction in which the static magnetic field parallel to the central axis of the processing chamber is strengthened in the first static magnetic field; the control device controls the electromagnet so that the angle of the magnetic force line of a third static magnetic field with respect to the surface to be processed of the substrate to be processed is a desired angle; and the third static magnetic field is a static magnetic field which is obtained from superposing the first static magnetic field and the second static magnetic field.

Description

[Technical Field]

[0001] This disclosure relates to a plasma processing apparatus and a plasma processing method, and more particularly to a plasma processing apparatus and a plasma processing method that generate plasma in a processing chamber using the interaction of microwaves and a static magnetic field, and perform plasma processing on a substrate to be processed placed in the processing chamber. [Background technology]

[0002] Plasma processing equipment is used in the production of semiconductor integrated circuit elements (hereinafter simply referred to as semiconductor elements or elements) that make up semiconductor integrated circuits. Miniaturization of elements has progressed in order to improve element performance and reduce costs. Conventionally, two-dimensional miniaturization of elements has increased the number of elements that can be manufactured from a single substrate (semiconductor wafer, semiconductor substrate, or simply referred to as a substrate), lowering the manufacturing cost per element, and has also improved the performance of semiconductor integrated circuits through the effect of miniaturization such as shortening wiring length. However, when the dimensions of semiconductor elements reach the nanometer order, close to the dimensions of atoms, the difficulty of two-dimensional miniaturization increases dramatically, and countermeasures such as the application of new materials and three-dimensional element structures are being taken. These changes have further increased the difficulty of manufacturing and the number of manufacturing processes, and the increase in manufacturing costs has become a serious problem.

[0003] If even tiny foreign objects or contaminants adhere to semiconductor integrated circuit elements during manufacturing, it can result in fatal defects. Therefore, semiconductor integrated circuit elements are manufactured in cleanrooms where foreign objects and contaminants are eliminated and temperature and humidity are optimally controlled. As elements become smaller, the cleanliness required for the cleanrooms used in manufacturing increases, and the construction and maintenance of cleanrooms become prohibitively expensive. For this reason, efficient use of the cleanroom space is essential for production. From this perspective, there is a strong demand for miniaturization and cost reduction of semiconductor manufacturing equipment.

[0004] Furthermore, the in-plane uniformity of the plasma treatment on the substrate being processed is also important. In the manufacturing of semiconductor integrated circuit elements, a 300 mm diameter disc-shaped silicon wafer is often used as the substrate to be processed. Numerous semiconductor integrated circuit elements are created on this silicon wafer. If the in-plane uniformity of the plasma treatment is poor, the number of good products (good semiconductor chips) that satisfy the product specifications and can be obtained from a single silicon wafer will decrease. Similarly, the stability of the plasma treatment for each substrate being processed is also important. If the quality of the plasma treatment is unstable, for example, if the quality changes over time, the proportion of good products will similarly decrease.

[0005] In plasma processing equipment that generates plasma using electromagnetic waves, plasma processing equipment using microwaves with a frequency of several GHz, typically 2.45 GHz, is widely used. In particular, there are plasma processing equipment that utilize the electron cyclotron resonance (ECR) phenomenon, which occurs by combining microwaves and a static magnetic field. This type of plasma processing equipment has excellent features, such as the ability to generate plasma relatively stably even under conditions where plasma generation is normally difficult, such as extremely low pressure, and the ability to control the plasma distribution by the distribution of the static magnetic field.

[0006] It is generally known that electrons moving in a plasma with an applied static magnetic field are subjected to a force called the Lorentz force, which suppresses diffusion in the direction perpendicular to the static magnetic field. Similarly, it is known that ions in a plasma diffuse together with electrons due to the electric field generated between them, a phenomenon called bipolar diffusion. Due to these effects, the density distribution of the plasma can be controlled by applying a static magnetic field to the plasma and suppressing diffusion in the direction perpendicular to the static magnetic field.

[0007] Plasma processing equipment used in the manufacturing of semiconductor integrated circuit elements often employs a type of plasma called low-temperature plasma, where the temperatures of electrons and ions differ significantly. Although it depends on the plasma generation conditions, in low-temperature plasma, the electron temperature is said to be on the order of a few eV, and the ion temperature is on the order of 0.1 eV. Normally, the densities of electrons and ions are almost equal in the plasma, and a nearly electrically neutral state is maintained. However, near the surface where the plasma is in contact with the substrate to be processed or the processing chamber, high-temperature, high-speed electrons escape to the wall, creating a region called a sheath where ions are left behind in excess.

[0008] Within the sheath, strong electric fields are locally generated due to charge separation. The sheath, particularly at the interface with the substrate being processed, significantly impacts the quality of the plasma treatment. When high-frequency power is applied to the substrate, a DC bias voltage is generated on the substrate due to the voltage-current characteristics of the sheath, allowing control of the energy of ions in the plasma incident on the substrate surface. Optimizing this energy can improve plasma treatment quality, such as etching speed and shape, in the case of plasma etching. For example, in plasma processing equipment, a high-frequency power supply (Radio frequency (RF) power supply) with frequencies ranging from 400 kHz to 13.56 MHz is electrically connected to the substrate to apply a high-frequency bias to the sheath. Automatic matching devices are often used to resolve power mismatches during connection.

[0009] Theoretical treatment of sheaths is described in many publicly available documents. For example, Non-Patent Document 1 states that ions are incident at a velocity greater than or equal to the Bohm velocity shown in Equation 1 at the interface between the plasma and the sheath.

[0010] V Bohm =√((eT e ) / m i )...Equation 1 Here, V Bohm : Bohm velocity (m / s), e: electron charge (= 1.602 × 10⁻¹⁰) -19 Cm i : Mass of ions (kg), T e: This is the electron temperature (V).

[0011] In other words, in a sheath in contact with the substrate to be processed, ions are known to be incident at the sheath edge with an initial velocity greater than the Bohm velocity, accelerated by the sheath's electric field, and reach the substrate. The sheath's electric field can be controlled by a high-frequency bias, which can improve the quality of the plasma processing.

[0012] In the aforementioned plasma processing apparatus using electron cyclotron resonance (ECR), microwaves are often introduced parallel to the static magnetic field from a region with a strong static magnetic field, and furthermore, the microwaves are often introduced as circularly polarized waves (hereinafter referred to as R-waves) in which the electric field rotates clockwise relative to the static magnetic field. This is because it has been theoretically proven that R-waves do not have a cutoff in the strong magnetic field region exceeding the ECR condition and can propagate even in the high-density region. Here, the ECR condition refers to the static magnetic field in which the electron cyclotron frequency and the microwave frequency coincide. When the microwave frequency is 2.45 GHz, the ECR condition corresponds to a static magnetic field of 875 gauss. In other words, R-waves introduced from a strong magnetic field region exceeding the ECR condition can propagate through the plasma even when a high-density plasma is generated, so it is believed that microwave power can be propagated to the region where ECR occurs (the electron cyclotron resonance (ECR) surface: referred to as the ECR surface) and absorbed efficiently. Furthermore, the surface of the substrate to be processed is often positioned in a weak magnetic field area, roughly perpendicular to the static magnetic field, facing the surface into which the microwaves are introduced.

[0013] Generally, when manufacturing semiconductor integrated circuit elements using plasma etching equipment, processing conditions are adjusted to optimize the etching process quality according to the film thickness and type of the film to be processed. Processing conditions include the type and flow rate of the gas used for etching, the pressure in the plasma processing chamber, the power for plasma generation, and the RF bias power applied to the substrate to be processed. In particular, in etching equipment using an ECR plasma source, the diffusion and generation region of the plasma can be controlled by the static magnetic field, and the distribution of the static magnetic field is an important parameter. In ECR plasma, it is believed that absorption of microwave power into the plasma occurs strongly and locally at the ECR surface, and the position of the ECR surface is especially important for controlling the plasma generation region. It is thought that the generation of ions and chemically active radicals is vigorous near the ECR surface. By adjusting the distance between the ECR surface and the surface of the substrate to be processed, the ratio and density of ions and radicals on the surface of the substrate to be processed can be adjusted, making it possible to optimize the plasma processing quality, such as the processed shape.

[0014] In plasma etching, gas flow rate and pressure are also important parameters. By applying an RF bias to the substrate to be processed and drawing in ions from the plasma, the etching rate at the ion collision surface (the surface of the substrate to be processed) can be increased, thereby improving the anisotropy of the processed shape. At low pressure, the collision frequency between ions and neutral gas molecules decreases, and the straight-line propagation of ions increases, so etching at low pressure is effective in improving the anisotropy of the processed shape. Furthermore, increasing the gas flow rate increases the supply of active species necessary for the etching reaction, and also reduces the re-adhesion of reaction products to the surface of the substrate to be processed, which is advantageous for increasing the etching rate. Thus, etching with low pressure and high gas flow rate is advantageous for high-quality processing. However, low pressure and high gas flow rate are in a trade-off relationship that is difficult to achieve simultaneously. Therefore, it is important to increase the vacuum evacuation capacity of the plasma etching apparatus.

[0015] Figure 1 shows etching apparatus 0100 as a comparative example of a plasma processing apparatus using ECR. Electromagnets 0102 are installed around a roughly cylindrical plasma processing chamber 0107, allowing a static magnetic field to be applied to generate ECR within the plasma processing chamber 0107. The electromagnets 0102 are composed of multi-stage solenoid coils. A yoke 0110 is provided around the outside of these solenoid coils. By adjusting the strength of the magnetic field generated by each solenoid coil, the static magnetic field distribution within the processing chamber 0107 can be controlled. Microwaves are supplied from a circular waveguide 0101 installed along the central axis of the plasma processing chamber 0107 to a cavity 0104. The introduced microwaves have their electromagnetic field distribution shaped in the cavity 0104 and are then introduced into the plasma processing chamber 0107 through a microwave introduction window 0105 and a shower plate 0106 located on the surface facing the surface of the substrate 0103 to be processed inside the plasma processing chamber 0107. Microwaves with a frequency of 2.45 GHz are often used. The gas used for etching is supplied from a gas supply device (not shown) into the processing chamber 0107 through a minute gap (not shown) between the microwave introduction window 0105 and the shower plate 0106, and through multiple minute gas supply holes (not shown) provided in the shower plate 0106. Quartz is often used for the microwave introduction window 0105 and the shower plate 0106 as it is a material that transmits microwaves and does not adversely affect the plasma processing. In addition, the inner surface of the plasma processing chamber 0107 is often protected by an inner cylinder made of quartz or the like to prevent damage from the plasma. In this example, a silicon substrate 0103 with a diameter of 300 mm was used as the substrate to be processed. [Prior art documents] [Non-patent literature]

[0016] [Non-Patent Document 1] Michael A. Lieberman and Allan J. Lichtenberg, Principles of plasma discharges and materials processing, Second Edition, Wiley-Interscience, First published 27 January 2005, John Wiley & Sons, Inc.

Summary of the Invention

Problems to be Solved by the Invention

[0017] Etching was performed using the plasma etching apparatus 0100 shown in FIG. 1, and shape evaluation was performed. As a result, depending on the processing conditions, shape abnormalities that were asymmetric in the inner and outer directions of the substrate to be processed 0103 were sometimes observed at the outer peripheral portion of the substrate to be processed 0103. The shape of plasma etching is a complex phenomenon involving various factors, and it is difficult to identify the cause. However, it may be caused by the reattachment of the reaction products of the etching generated from the substrate to be processed 0103. That is, the density distribution of the reaction products on the substrate to be processed 0103 may be non-uniform and may have occurred due to more reattachment on one side.

[0018] The present disclosure aims to provide a technique for preventing defects in plasma processing near the outer peripheral portion of the substrate to be processed. Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0019] The outline of typical ones among the present disclosure will be briefly described as follows.

[0020] According to one aspect of the present disclosure, a processing chamber in which the substrate to be processed is plasma processed, a high-frequency power supply that supplies microwave power through a waveguide, a dielectric plate disposed above the processing chamber through which the microwave passes, A sample stand on which the substrate to be processed is placed, An electromagnet is arranged to surround the processing chamber and generate a first static magnetic field, Displaced below the substrate to be processed Disc-shaped permanent magnet and, The system comprises a control device for controlling the electromagnet, The aforementioned Permanent magnet teeth, A permanent magnet that strengthens the first static magnetic field in a direction parallel to the central axis of the processing chamber and generates a second static magnetic field that weakens the first static magnetic field in the radial direction of the central axis. , The control device controls the electromagnet so that the angle of the magnetic field lines of the third static magnetic field with respect to the surface of the substrate to be processed becomes a desired angle. The third static magnetic field is a static magnetic field formed by the superposition of the first static magnetic field and the second static magnetic field. The diameter of the sample stage is greater than the diameter of the permanent magnet. The diameter of the permanent magnet is larger than the diameter of the substrate being processed. A technology (plasma processing apparatus or etching method) characterized by the above is provided. [Effects of the Invention]

[0021] According to this disclosure, it is possible to prevent defects in plasma processing near the outer periphery of the substrate to be processed.

[0022] More specifically, the control device controls multiple stages of electromagnets to control the angle of the static magnetic field generated by the multiple stages of electromagnets and the static magnetic field generator with respect to the surface of the substrate being processed. Therefore, the aforementioned problem can be solved by controlling the incidence angle of ions incident on the substrate being processed through etching using the plasma processing apparatus or plasma processing method according to this disclosure. That is, since ions are incident along magnetic field lines on the sheath end formed on the surface of the substrate being processed, the angle of the magnetic field lines with respect to the surface of the substrate being processed near the outer periphery of the substrate can be controlled to be, for example, almost perpendicular (approximately 90°). As a result, shape abnormalities can be improved by controlling the incidence angle of ions near the outer periphery of the substrate being processed. [Brief explanation of the drawing]

[0023] [Figure 1]Figure 1 is a schematic side cross-sectional view of a microwave plasma etching apparatus related to a comparative example. [Figure 2] Figure 2 is a schematic side cross-sectional view of a microwave plasma etching apparatus according to an embodiment. [Figure 3] Figure 3 is a schematic diagram of the magnetic field line distribution of a microwave plasma etching apparatus according to an embodiment. [Figure 4] Figure 4 is an explanatory diagram of the control device according to an embodiment. [Figure 5] Figure 5 is a graph showing the magnetic field line angles on the substrate being processed. [Figure 6] Figure 6 is a graph showing the relationship between ECR height and the radius of the substrate being processed. [Figure 7] Figure 7 is a graph showing the relationship between the magnetic field line angle on the substrate being processed and the radius of the substrate being processed. [Modes for carrying out the invention]

[0024] The embodiments will be described below with reference to the drawings. However, in the following description, the same reference numerals will be used for the same components, and repeated explanations may be omitted. In addition, the drawings may be more schematic than the actual embodiments in order to make the explanation clearer, but they are merely examples and do not limit the interpretation of the present invention.

[0025] A microwave plasma etching apparatus according to an embodiment will be described using Figures 2 to 7. Figure 2 is a schematic side cross-sectional view (vertical cross-sectional view) of a microwave plasma etching apparatus according to an embodiment. The substrate to be processed 0210 is, for example, a disc-shaped single-crystal silicon substrate with a diameter of 300 mm, and a semiconductor integrated circuit element is created on the substrate to be processed 0210. In the microwave plasma etching apparatus (hereinafter also simply called a plasma etching apparatus or plasma processing apparatus) 0200 shown in Figure 2, plasma generated inside a substantially cylindrical processing chamber 0209 is used to perform plasma processing (in this case, etching) on ​​the structure formed in another process on the surface of the substrate to be processed 0210, which is placed on a substrate electrode 0211 as a sample stage. When the substrate to be processed 0210 is viewed from the top side, it is disc-shaped, and plasma processing that is axially symmetric with respect to the central axis passing through the center point of the disc-shaped substrate to be processed 0210 is required. For this reason, the plasma etching apparatus 0200 also has a structure that is basically axially symmetric with respect to the central axis when viewed from the top side. Furthermore, the substrate electrode 0211 has a circular shape when viewed from the top side, and is axially symmetric with respect to the central axis. Here, the center point of the disc-shaped substrate 0210 to be processed corresponds to the center point O of the substrate 0210 to be processed shown in Figure 3. The central axis passing through the center point (O) of the substrate 0210 to be processed corresponds to the Z-axis as the central axis shown in Figure 3. Axis symmetry with respect to the central axis means axial symmetry with respect to the Z-axis in Figure 3. An axially symmetric structure means a structure that is axially symmetric with respect to the Z-axis in Figure 3. The Z-axis as the central axis can be rephrased as the central axis of the plasma etching apparatus 0200, or the central axis of the processing chamber 0209. In this case, the center point (O) of the substrate 0210 to be processed and the center point of the substrate electrode 0211 are positioned on the axis of the central axis.

[0026] Microwaves generated from the microwave source 0230, which acts as a radio frequency power supply, are propagated to the circular waveguide 0201 via a microwave propagation device 0231, which includes an isolator, an automatic matching circuit, a rectangular waveguide, and a circular polarization generator. In other words, the microwave source 0230 supplies microwave power to the circular waveguide 0201. The circular waveguide 0201 is cylindrical or circular in shape, with its cylindrical center located on the central axis (Z-axis). That is, the center of the circular waveguide 0201 is coaxial with the central axis of the processing chamber 0209. The microwave source 0230 is configured to supply microwave power to the processing chamber 0209 via the waveguide 0201.

[0027] The circularly polarized microwaves from the circular waveguide 0201 are the lowest-order mode of the circular waveguide 0201, which is the TE (Triple Emission). 11 The signal is transmitted to the cavity 0206 in this mode. In this example, a microwave with a frequency of 2.45 GHz was used. The circular waveguide 0201 was, for example, one with a diameter that allows only the lowest-order modulus to propagate.

[0028] The microwave electromagnetic field is shaped in the cavity 0206, and the shaped electromagnetic field is introduced into the processing chamber 0209 through the microwave introduction window 0207 and the shower plate 0208. The microwave introduction window 0207 and the shower plate 0208 are positioned above the processing chamber 0209 and can be considered as dielectric plates that can transmit microwaves. The microwave introduction window 0207 can be considered to be positioned on one side intersecting the central axis of the processing chamber 0209. As the material for the microwave introduction window 0207 and the shower plate 0208, it is desirable to use a dielectric material that has low microwave loss, high plasma resistance, and does not adversely affect plasma processing. In this embodiment, quartz was used as the material for the microwave introduction window 0207 and the shower plate 0208. The gas used for the etching process, supplied from a gas supply unit (not shown), is supplied in a predetermined amount into the processing chamber 0209 through a minute gap (not shown) between the microwave introduction window 0207 and the shower plate 0208, and through a plurality of supply holes (not shown) provided in the shower plate 0208.

[0029] Three stages of electromagnets, 0203, 0204, and 0205, are provided around the outer periphery of the cylindrical processing chamber 0209. These multiple stages of electromagnets 0203, 0204, and 0205 can be considered to be arranged coaxially (or axially symmetrically) with respect to the central axis, surrounding the processing chamber 0209. Furthermore, a yoke 0202 is provided around the outer periphery of these electromagnets 0203, 0204, and 0205. The yoke 0202 is preferably made of a material with high magnetic permeability; in this example, iron was used. The electromagnets 0203, 0204, and 0205 are electrically connected to a control device 0250, which is configured to control the drive current values ​​of the electromagnets 0203, 0204, and 0205.

[0030] In this example, the first electromagnet 0203, which is the upper electromagnet, is installed so as to surround the upper outer portion of the processing chamber 0209, excluding the area where the circular waveguide 0201 is installed. The second electromagnet 0204, which is the middle electromagnet, is located below the first electromagnet 0203 and is installed so as to surround the upper outer side portion of the processing chamber 0209. In this example, the second electromagnet 0204 is installed around the upper outer side portion of the processing chamber 0209, surrounding the outer perimeter of the cavity 0206 and the microwave introduction window 0207. The third electromagnet 0205, which is the lower electromagnet, is located below the second electromagnet 0204 and is installed so as to surround the side portion of the middle outer portion of the processing chamber 0209. In this example, the third electromagnet 0205 is located around the side portion of the intermediate outer part of the processing chamber 0209 between the shower plate 0208 and the static magnetic field generator 0212, which will be described later.

[0031] In this embodiment, as an example, three electromagnets 0203, 0204, and 0205 were used. The number of electromagnet stages may be increased to four or five stages, depending on the need to finely adjust the distribution of the static magnetic field. Alternatively, the number of electromagnet stages may be reduced to two stages. In this embodiment, these electromagnets 0203, 0204, and 0205 create a divergent magnetic field where the static magnetic field is strong in the upper region of the processing chamber 0209 or the region on the microwave input window 0207 side, and weak in the lower region of the processing chamber 0209 (the region of the processing chamber 0209 corresponding to the area below the shower plate 0208, or the region of the processing chamber 0209 corresponding to the area above the substrate electrode 0211, which will be described later). The configuration of the electromagnets 0203, 0204, and 0205 is axially symmetric (axially symmetric with respect to the Z-axis) when viewed from above, and the static magnetic field generated by these electromagnets 0203, 0204, and 0205 is also axially symmetric when viewed from above. With this configuration, an ECR surface (electron cyclotron resonance (ECR) surface) with an ECR condition of 875 gauss can be set within the processing chamber 0209, and the drive current value supplied to the electromagnets 0203, 0204, and 0205 can be adjusted by the control device 0250 to control the distance between the ECR surface and the processing surface of the substrate 0210 (also called the ECR height (h)) and the shape of the ECR surface. Plasma can be generated within the processing chamber 0209 through the interaction between the input microwaves and the static magnetic field. Here, the electron cyclotron resonance can be considered as an electron cyclotron resonance resulting from the interaction between microwaves from microwave source 0230 and a static magnetic field (also called the first static magnetic field) generated by electromagnets 0203, 0204, and 0205.

[0032] The processing chamber 0209 is provided with a substrate 0210 to be processed and a substrate electrode 0211 having a mounting surface for holding the substrate 0210. The substrate electrode 0211 is provided inside the processing chamber 0209, facing the microwave introduction window 0207, and the substrate 0210 to be processed is placed on the mounting surface of the substrate electrode 0211 with its center point aligned coaxially with the central axis.

[0033] The substrate electrode 0211 incorporates a mechanism for electrostatically attracting and holding the substrate 0210 to be processed, a mechanism for temperature control of the substrate 0210 to be processed, and a mechanism for supplying an RF (Radio Frequency) bias to the substrate 0210 to be processed. The processing chamber 0209 is equipped with a vacuum evacuation device 0214 via an exhaust speed adjustment mechanism 0213. The exhaust speed adjustment mechanism 0213, the vacuum evacuation device 0214, and a gas supply mechanism (not shown) supply a predetermined gas to the processing chamber 0209 at a predetermined pressure and flow rate. Since the etching process is also affected by the gas flow in the processing chamber 0209, the structure (for example, the arrangement of the multiple supply holes provided in the shower plate 0208) is axially symmetrical so that the gas flow is axially symmetrical when viewed from the top.

[0034] A static magnetic field generator 0212 is provided on the back side of the substrate electrode 0211, facing the mounting surface of the substrate electrode 0211. In this example, the static magnetic field generator 0212 is built into the substrate electrode 0211. When the substrate 0210 to be processed is placed on the mounting surface of the substrate electrode 0211, the static magnetic field generator 0212 can also be described as being located on the back side of the substrate 0210 with respect to the processing surface of the substrate 0210. Alternatively, the static magnetic field generator 0212 can be described as being located below the substrate 0210 to be processed.

[0035] The static magnetic field on the surface of the substrate 0210 being processed is a superimposed (combined) static magnetic field (also called a third static magnetic field) of a first static magnetic field generated by electromagnets 0203, 0204, and 0205 and a second static magnetic field generated by a static magnetic field generator 0212. The static magnetic field generator 0212 is configured to generate a second static magnetic field in a direction that strengthens the static magnetic field parallel to the central axis of the processing chamber 0209 within the first static magnetic field. The static magnetic field generator 0212 can control the angle of the static magnetic field (third static magnetic field) to be perpendicular (90 degrees) or nearly perpendicular (approximately 90 degrees) to the surface of the substrate 0210 being processed. Electromagnets or permanent magnets can be used as the static magnetic field generator 0212. In this embodiment, an example configuration using a permanent magnet as the static magnetic field generator 0212 will be described. Using electromagnets as the static magnetic field generator 0212 has the advantage that the magnitude and distribution of the static magnetic field can be easily controlled by adjusting the drive current. However, in this case, a cooling mechanism and a current supply mechanism are required, which may be disadvantageous to miniaturizing the static magnetic field generator 0212. Furthermore, it is desirable to place the static magnetic field generator 0212 close to the surface of the substrate 0210 to be processed. If the static magnetic field generator 0212 is placed far from the surface of the substrate 0210 to be processed, the static magnetic field generated by the static magnetic field generator 0212 needs to be a strong static magnetic field. This makes it even more difficult to miniaturize the static magnetic field generator 0212. If a large electromagnet is in the vacuum evacuation path, the evacuation performance will decrease, so in this embodiment, a static magnetic field generator 0212 using a permanent magnet that can be miniaturized is placed near the substrate 0210 to be processed. Specifically, the static magnetic field generator 0212 using a permanent magnet is provided on the back side of the substrate electrode 0211 that faces the mounting surface of the substrate electrode 0211 on the substrate 0210 to be processed. The static magnetic field generator 0212 using a permanent magnet has a circular shape when viewed from above. Similarly, the substrate electrode 0211 also has a circular shape when viewed from the top.

[0036] Figure 3 is a schematic diagram of the magnetic field line distribution of a microwave plasma etching apparatus according to an embodiment. Figure 3 also shows the arrangement of the circular waveguide 0201, the substrate to be processed 0210, the substrate electrode 0211, and the static magnetic field generator 0212 as viewed from above, and the relationship between the origin O, the z axis, and the r axis, which will be described later. Note that the short control lines indicated by the dotted arrows output from the control device 0250 are actually connected to the electromagnets 0203, 0204, and 0205, as in Figure 2, but are shown as short control lines for simplification in Figure 3.

[0037] Figure 3 schematically shows the magnetic field lines 0301 (also called the first magnetic field lines) generated only by electromagnets 0203, 0204, and 0205, and the magnetic field lines 0302 (also called the second magnetic field lines) generated only by the static magnetic field generator 0212. In reality, the static magnetic fields generated by both magnetic field lines 0301 and 0302 are superimposed, but in Figure 3, for the sake of explaining the operation, the magnetic field lines 0301 and 0302 are shown as if the other were not present. In Figure 3, when viewed from the top side, the z-axis is shown in the vertical direction and the r-axis is shown in the radial direction, with the central axis of the surface of the disc-shaped substrate 0210 being processed being the origin O. The magnetic field lines 0301 generated by electromagnets 0203, 0204, and 0205 are directed downward along the z-axis, and the magnetic field lines 0302 generated by the static magnetic field generator 0212 are also directed downward along the z-axis, creating a static magnetic field that reinforces each other. In other words, the static magnetic field generator 0212 generates a static magnetic field from magnetic field lines 0302 that reinforce the static magnetic field parallel to the central axis, which is generated by the magnetic field lines 0301 generated by the multiple stages of electromagnets 0203, 0204, and 0205. Conversely, it is also possible to use static magnetic fields that are directed upward from both sides. On the other hand, when we look at the component in the r-axis direction on the surface of the substrate 0210 being processed (on the r-axis), the magnetic field lines 0301 from the electromagnets 0203, 0204, and 0205 are outward, and the magnetic field lines 0302 from the static magnetic field generator 0212 are inward. It can be seen that the r-direction component of the static magnetic field cancels each other out (depletes) due to the superposition of the two. In other words, in the configuration shown in Figure 3, the static magnetic field is adjusted to be more perpendicular to the surface of the substrate 0210 being processed by the action of the static magnetic field generator 0212 near the surface of the substrate 0210 being processed. Figure 3 explains the case of a three-stage configuration with electromagnets 0203, 0204, and 0205, but it is clear that a similar effect of perpendicularizing the static magnetic field can be obtained with other configurations of electromagnet stages. However, when the number of electromagnet stages is small, the number of parameters for adjustment is small, so the degree of freedom of adjustment may decrease, as will be discussed later. To adjust parameters such as the height of the ECR surface while perpendicularizing the static magnetic field on the substrate 0210 to be processed (described later), it is preferable to provide two or more stages of electromagnets (0203, 0204, 0205).

[0038] As shown in Figure 3, when viewed from above, the centers of the circular waveguide 0201, substrate electrode 0211, substrate 0210, substrate electrode 0211, and static magnetic field generator 0212 are arranged coaxially so as to coincide with the origin O, which is the central axis of the surface of the workpiece of the disc-shaped substrate 0210, and are arranged axially symmetric with respect to the z-axis passing through the origin O. When viewed from above, the sizes of the substrate electrode 0211, substrate 0210, substrate electrode 0211, and static magnetic field generator 0212 are such that the disc-shaped (or circular) substrate electrode 0211 is the largest, followed by the disc-shaped (or circular) static magnetic field generator 0212 using a permanent magnet, which is the second largest, and the disc-shaped (or circular) substrate 0210 is the third largest. This allows the angle of the third static magnetic field, which is a combination of the first static magnetic fields of electromagnets 0203, 0204, and 0205 and the second static magnetic field of the static magnetic field generator 0212, at the outer periphery of the surface of the substrate 0210 to be perpendicular (90 degrees) or nearly perpendicular (approximately 90 degrees) to the surface of the surface of the substrate 0210 to be treated.

[0039] Figure 4 illustrates the operation of the control device 0250 that controls the electromagnets 0203, 0204, and 0205. Figure 4 is an explanatory diagram of the control device according to the embodiment. Numbers and other designations shown in Figures 2 and 3 will be used as needed in the explanation. The control device 0250 is composed of a current control device 400 and a plurality of current sources CS1, CS2, and CS3. In this example, the plurality of current sources CS1, CS2, and CS3 correspond to the three stages of electromagnets 0203, 0204, and 0205, and three examples of current sources CS1, CS2, and CS3 are shown.

[0040] The current control device 400 has the function of determining the drive currents for electromagnets 0203, 0204, and 0205 such that the angle of the static magnetic field at the surface of the substrate 0210 being processed is perpendicular to the surface of the substrate being processed, while satisfying the input static magnetic field specification 401. The static magnetic field specification 401 is input to the current control device 400, and the current control device 400 determines current control signals S1, S2, and S3 according to the static magnetic field specification 401 and sends them to current sources CS1, CS2, and CS3. The current sources CS1, CS2, and CS3 supply drive currents I1, I2, and I3 to the electromagnets 0203, 0204, and 0205 respectively according to the current control signals S1, S2, and S3. In this way, the current control device 400 can control the magnetic field lines 0301 generated from multiple stages of electromagnets 0203, 0204, and 0205 and the static magnetic field based thereon. Figure 4 illustrates the case where electromagnets 0203, 0204, and 0205 are arranged in three stages, but the same applies to other numbers of stages.

[0041] In this embodiment, the static magnetic field specification 401 is determined using the distance between the ECR surface on the central axis (z-axis) of the microwave plasma etching apparatus 0200 and the surface of the surface to be processed on the substrate 0210 (hereinafter referred to as ECR height (h)) as a parameter. This is because, as mentioned above, the ECR surface is an important parameter that affects the plasma processing characteristics. The static magnetic field specification 401 may consist of other items or multiple items, but the number of specification items that can be set is limited by the number of stages of electromagnets (0203, 0204, 0205). For example, when using one stage electromagnet, if the static magnetic field near the surface of the surface to be processed on the substrate 0210 is controlled perpendicular to the surface of the surface to be processed on the substrate 0210, the current value supplied to the electromagnet is uniquely determined, and there is no room to adjust the static magnetic field specification 401 such as the ECR height. In principle, a maximum of one static magnetic field specification 401 can be satisfied with two stages of electromagnets, and a maximum of two static magnetic field specification 401 can be satisfied with three stages. The same applies to electromagnets with four or more stages. Needless to say, redundancy can be introduced, for example, by making the static magnetic field specification 401 a single item for a three-stage electromagnet.

[0042] Generally, when there are a plurality of static magnetic field generation sources (0212), the overall static magnetic field is the superposition of the static magnetic fields when each static magnetic field generation source (0212) is individual. In the storage device within the current control device 400, there are stored, as reference data, the first distribution data in the processing chamber 0209 of the static magnetic flux density generated by the permanent magnet (0212) alone, and the second distribution data in the processing chamber 0209 of the static magnetic flux density generated by each of the plurality of stages of electromagnets (0203, 0204, 0205) driven with a predetermined current. The static magnetic flux density at an arbitrary coordinate (r, z) in the processing chamber 0209 can be obtained by linear superposition using these first distribution data and second distribution data, as shown in Equation 2 below.

[0043] [Number] B r (r,z): The r - component of the magnetic flux density at the coordinate (r, z) in the processing chamber when a current of I i (A) is passed through all the electromagnets i (i = 1, 2, 3) (here, electromagnet 1 corresponds to electromagnet 0203, electromagnet 2 corresponds to electromagnet 0204, and electromagnet 3 corresponds to electromagnet 0205). B z (r,z): The z - component of the magnetic flux density at the coordinate (r, z) in the processing chamber when a current of I i ? (A) is passed through all the electromagnets i (i = 1, 2, 3). B ir (r,z): The r - component of the magnetic flux density when a predetermined current I 0i (A) is passed through only the electromagnets i (i = 1, 2, 3) at the coordinate (r, z) in the processing chamber. B iz (r,z): The z - component of the magnetic flux density when a predetermined current I 0i (A) is passed through only the electromagnets i (i = 1, 2, 3) at the coordinate (r, z) in the processing chamber. B mr (r,z): The r - component of the magnetic flux density due only to the permanent magnet at the coordinate (r, z) in the processing chamber. B mz (r,z): The z - component of the magnetic flux density due only to the permanent magnet at the coordinate (r, z) in the processing chamber. In this embodiment, B ir B iz (i=1,2,3), B mr B mz These values ​​were determined in advance by theoretical calculations using the finite element method. Alternatively, values ​​measured using a magnetic sensor may be used, or theoretical calculations may be performed as needed.

[0044] For example, the r component of the magnetic flux density at a certain point (r0, z0) is a specific value B. 0r If you want to control it, as can be seen from Equation 2, the current I i It can be seen that there is a linear relationship between (i=1,2,3). For example, current I 1、 By applying I2 within the current-carrying range of electromagnets 0203 and 0204, the current I3 is determined. If this value is within the current-carrying range of electromagnet 0205, the magnetic flux density distribution can then be determined using Equation 2. From the obtained magnetic flux density distribution, the current I that satisfies the desired specifications can be found. 1、 I 2、 We can explore combinations of I3.

[0045] The above explanation was based on the case of an electromagnet with three stages, but the same principles apply to other numbers of stages as well.

[0046] In this embodiment, we want to control the angle of the magnetic field lines on the surface of the substrate 0210 to be perpendicular (or nearly perpendicular) to the surface of the substrate 0210. Furthermore, since a divergent magnetic field is used, the deviation of the magnetic field lines from perpendicular tends to increase as the distance from the center point O of the substrate 0210 increases. In addition, by setting the r component of the magnetic flux density to zero, the angle of the magnetic field lines can be made perpendicular to the surface of the substrate 0210. For the above reasons, we will control the r component of the magnetic flux density at the outermost periphery of the substrate 0210 to zero.

[0047] Figure 5 is a graph showing the angle of magnetic field lines on the substrate being processed. An example of controlling the angle of magnetic field lines on the substrate 0210 to be vertical will be explained using Figure 5. In the graph of Figure 5, the vertical axis shows the angle θ (°) of the magnetic flux density vector on the substrate 0210 with respect to the surface of the substrate 0210. The horizontal axis shows the radius r (mm) on the substrate. The graph compares the case where a permanent magnet is placed as a static magnetic field generator 0212 (with permanent magnet: shown by line L1) and the case where it is not placed (without permanent magnet: shown by line L2). By using a permanent magnet, the magnetic field lines were adjusted to be vertical (90°) at a radius of 150 mm, which is the outermost part of the 300 mm diameter substrate 0210. It can be seen that by using a permanent magnet, the magnetic field lines can be made vertical over almost the entire surface of the substrate 0210 (within the range of radius r from 0 mm to 150 mm).

[0048] Figure 6 is a graph showing the relationship between ECR height and the radius of the substrate being processed, and Figure 7 is a graph showing the relationship between the magnetic field line angle on the substrate being processed and the radius of the substrate being processed. Figures 6 and 7 show the results when the ECR height (h (mm)) is controlled to 150 mm, 170 mm, 185 mm, and 200 mm. Figure 6 shows the ECR height (h (mm)) at each radius (r (mm)), and Figure 7 shows the magnetic field line angle θ (°) on the substrate 0210 being processed. In Figure 7, the graphs with different current values ​​are almost overlapping, so there is only one line.

[0049] In Figure 6, line L21 represents the case where the ECR height (h (mm)) is adjusted to 150 mm, and the drive current values ​​(amperes: A) for electromagnets 0203, 0204, and 0205 are 27 A, 12 A, and 17 A, respectively. Line L22 represents the case where the ECR height (h (mm)) is adjusted to 170 mm, and the drive current values ​​(A) for electromagnets 0203, 0204, and 0205 are 27 A, 26 A, and 14 A, respectively. Line L23 represents the case where the ECR height (h (mm)) is adjusted to 185 mm, and the drive current values ​​(A) for electromagnets 0203, 0204, and 0205 are 27 A, 26 A, and 10 A, respectively. Line L24 is set to an ECR height (h(mm)) of 200mm, and the drive current values ​​for electromagnets 0203, 0204, and 0205 are 27A, 30A, and 4A, respectively.

[0050] In Figure 7, line L31 is the same as line L21, where the ECR height (h (mm)) is adjusted to 150 mm, and the drive current values ​​(A) for electromagnets 0203, 0204, and 0205 are 27A, 12A, and 17A. Line L32 is the same as line L22, where the ECR height (h (mm)) is adjusted to 170 mm, and the drive current values ​​(A) for electromagnets 0203, 0204, and 0205 are 27A, 26A, and 14A. Line L33 is the same as line L23, where the ECR height (h (mm)) is adjusted to 185 mm, and the drive current values ​​(A) for electromagnets 0203, 0204, and 0205 are 27A, 26A, and 10A. Line L34, like line L24, is the case where the ECR height (h (mm)) is adjusted to 200 mm, and the drive current values ​​(A) for electromagnets 0203, 0204, and 0205 are 27A, 30A, and 4A, respectively.

[0051] Therefore, as can be seen from Figures 6 and 7, when the substrate 0210 to be processed has a diameter of 300 mm, it can be seen that the ECR height h can be adjusted to a desired height from 150 mm to 200 mm when the radius r of the substrate 0210 to be processed is within 0 mm to 150 mm and the angle θ(°) of the magnetic field lines is almost vertical (90°). The diameter of the substrate 0210 to be processed is not limited to 300 mm; it may be smaller or larger than 300 mm.

[0052] This prevents defects in the plasma treatment near the outer periphery of the substrate 0210. In other words, the shape of the plasma treatment near the center of the substrate 0210 can be made identical to the shape of the plasma treatment near the outer periphery of the substrate 0210. Furthermore, the shape of the plasma treatment from near the center of the substrate 0210 to near the outer periphery can be made identical. Therefore, the quality of the plasma treatment can be made uniform across the entire treated surface of the substrate 0210.

[0053] Furthermore, since the distance between the ECR surface and the surface of the substrate to be processed can be adjusted, the ratio and density of ions and radicals on the surface of the substrate 0210 can be adjusted, making it possible to optimize the quality of plasma processing, such as the plasma processing shape.

[0054] Here, the current control device 400 controls the drive current values ​​I1, I2, and I3 supplied to the multiple stages of electromagnets 0203, 0204, and 0205, as shown in (A)-(C) below.

[0055] (A) The current control device 400 controls the drive current values ​​I1, I2, I3 supplied to the multiple stages of electromagnets 0203, 0204, and 0205, thereby controlling the angle of the static magnetic field (third static magnetic field) based on magnetic field lines that are combined (superimposed) of the static magnetic field (first static magnetic field) based on magnetic field lines 0301 from the multiple stages of electromagnets 0203, 0204, and 0205 and the static magnetic field (second static magnetic field) based on magnetic field lines 0302 from the static magnetic field generator 0212, with respect to the surface of the substrate to be processed. In other words, the current control device 400 is configured to control the electromagnets (0203, 0204, 0205) so that the angle of the magnetic field lines of the third static magnetic field with respect to the surface of the substrate to be processed is a desired angle.

[0056] (B) The current control device 400 controls the drive current values ​​of the multiple electromagnets 0203, 0204, and 0205 so that 1) the angle of the third static magnetic field with respect to the surface of the surface to be processed is approximately perpendicular (about 90 degrees) at the outer periphery of the surface to be processed of the substrate 0210, and 2) the height between the ECR surface and the surface of the surface to be processed of the substrate 0210 is a desired height.

[0057] (C) The current control device 400 also controls the drive current values ​​of the multiple stages of electromagnets 0203, 0204, and 0205 so that the angle of the third static magnetic field with respect to the surface of the substrate 0210 to be processed is approximately perpendicular (about 90 degrees) over the entire surface of the substrate to be processed.

[0058] The plasma processing method using the plasma etching apparatus 0200 according to this embodiment includes the following steps S1, S2, S3, and S4. (Step S1) A substrate loading process in which the substrate 0210 to be processed is placed on the mounting surface of the substrate electrode 0211 in the processing chamber 0209. (Step S2) Plasma generation process in which plasma is generated inside processing chamber 0209. (Step S3) A plasma treatment process in which gas is supplied into the processing chamber 0209 to perform plasma treatment. (Step S4) A substrate removal step in which the substrate 0210 to be processed is removed from the processing chamber 0209 after the plasma processing step is completed.

[0059] In step S2, the multiple stages of electromagnets 0203, 0204, and 0205 generate a first static magnetic field based on the first magnetic field lines 0301 under the control of the current control device 400.

[0060] In step S2, as previously described, the current control device 400 controls the drive current values ​​I1, I2, I3 supplied to the multi-stage electromagnets 0203, 0204, and 0205, as shown in (A)-(C). In other words, step S2 has a first step of controlling the multi-stage electromagnets 0203, 0204, and 0205 so that the angle of the magnetic field lines of the third static magnetic field with respect to the surface of the substrate 0210 to be processed is a desired angle. Furthermore, step S2 includes a second step of controlling the multi-stage electromagnets 0203, 0204, and 0205 so that the height from the surface of the substrate 0210 to be processed is a desired height. Here, the first step is the step of controlling the multi-stage electromagnets 0203, 0204, and 0205 so that the angle of the magnetic field lines of the third static magnetic field with respect to the outer periphery of the surface of the substrate 0210 to be processed is approximately 90 degrees. Furthermore, the first step is to control multiple electromagnets 0203, 0204, and 0205 so that the angle of the magnetic field lines of the third static magnetic field over the entire surface of the substrate 0210 to be processed is approximately 90 degrees. Note that the plasma generation step (step S2) and the plasma processing step (step S3) may sometimes be defined as a single step.

[0061] Therefore, the aforementioned problem can be solved because the incidence angle of ions incident on the substrate 0210 can be controlled by etching using the plasma processing apparatus 0200 or plasma processing method according to this disclosure. Since ions are incident along magnetic field lines on the sheath end formed on the surface of the surface to be processed of the substrate 0210, the angle of the magnetic field lines with respect to the surface of the surface to be processed of the substrate 0210 near the outer periphery of the substrate 0210 can be controlled to be, for example, nearly perpendicular (90°). As a result, the incidence angle of ions can be controlled near the outer periphery of the substrate 0210, improving shape abnormalities in plasma processing and improving the quality of plasma processing, such as the plasma processed shape.

[0062] The above describes the case where the magnetic field lines on the substrate 0201 to be processed are controlled perpendicular to the surface of the substrate, but they can also be controlled to a predetermined angle. That is, in addition to the ECR height, the angle of the magnetic field lines relative to the surface of the substrate to be processed may be added to the static magnetic field specifications. The asymmetrical shape at the outer edge of the substrate to be processed, which was observed in the plasma etching apparatus of the comparative example, can be improved by controlling the angle of incidence of ions.

[0063] The disclosure made by the Discloser has been described in detail based on embodiments, but it goes without saying that the disclosure is not limited to the above embodiments and can be modified in various ways. [Explanation of symbols]

[0064] 0101: Circular waveguide, 0102: Electromagnet, 0103: Substrate to be processed, 0104: Cavity, 0105: Microwave introduction window, 0106: Shower plate, 0107: Plasma processing chamber, 0201: Circular waveguide, 0202: Yoke, 0203: Electromagnet, 0204: Electromagnet, 0205: Electromagnet, 0206: Cavity, 0207: Microwave introduction window, 0208: Shower plate, 0209: Processing chamber, 0210: Substrate to be processed, 0211: Substrate electrode, 0212: Static magnetic field generator, 0213: Exhaust speed adjustment mechanism, 0214: Vacuum exhaust device, 0250: Control device, 0301: Magnetic field lines (first magnetic field lines), 0302: Magnetic field lines (second magnetic field lines), 400: Current control device, 401: Static magnetic field specifications.

Claims

1. A processing chamber in which the substrate to be processed is subjected to plasma treatment, A high-frequency power supply that provides microwave power via a waveguide, A dielectric plate, through which the microwaves are transmitted, is positioned above the processing chamber. A sample stand on which the substrate to be processed is placed, An electromagnet is arranged to surround the processing chamber and generate a first static magnetic field, A disc-shaped permanent magnet is positioned below the substrate to be processed, The system comprises a control device for controlling the electromagnet, The permanent magnet is a permanent magnet that generates a second static magnetic field that strengthens the first static magnetic field in a direction parallel to the central axis of the processing chamber and weakens the first static magnetic field in the radial direction of the central axis. The control device controls the electromagnet so that the angle of the magnetic field lines of the third static magnetic field with respect to the surface of the substrate to be processed becomes a desired angle. The third static magnetic field is a static magnetic field formed by the superposition of the first static magnetic field and the second static magnetic field. The diameter of the sample stage is greater than the diameter of the permanent magnet. A plasma processing apparatus characterized in that the diameter of the permanent magnet is larger than the diameter of the substrate to be processed.

2. In the plasma processing apparatus according to claim 1, A plasma processing apparatus characterized in that the desired angle is approximately 90 degrees.

3. In the plasma processing apparatus according to claim 1, The control device is configured such that the angle of the outer periphery of the surface to be processed is approximately 90 degrees, The electromagnet is controlled so that the height from the surface to be processed to the electron cyclotron resonance surface becomes a desired height. The plasma processing apparatus is characterized in that the electron cyclotron resonance is an electron cyclotron resonance resulting from the interaction between the microwave and the first static magnetic field.

4. In the plasma processing apparatus according to claim 3, The plasma processing apparatus is characterized in that the control device controls the electromagnet so that the angle over the entire surface to be processed is approximately 90 degrees.

5. A plasma processing method using a plasma processing apparatus comprising: a processing chamber in which a substrate to be processed is subjected to plasma processing; a high-frequency power supply that supplies microwave power via a waveguide; a dielectric plate disposed above the processing chamber through which the microwaves pass; a sample stage on which the substrate to be processed is placed; an electromagnet disposed around the processing chamber to generate a first static magnetic field; and a disc-shaped permanent magnet disposed below the substrate to be processed, wherein The process includes a first step of controlling the electromagnet so that the angle of the magnetic field lines of the third static magnetic field with respect to the surface of the substrate to be processed becomes a desired angle. The permanent magnet is a permanent magnet that generates a second static magnetic field that strengthens the first static magnetic field in a direction parallel to the central axis of the processing chamber and weakens the first static magnetic field in the radial direction of the central axis. The third static magnetic field is a static magnetic field formed by the superposition of the first static magnetic field and the second static magnetic field. The diameter of the sample stage is greater than the diameter of the permanent magnet. A plasma treatment method characterized in that the diameter of the permanent magnet is larger than the diameter of the substrate to be treated.

6. In the plasma treatment method described in claim 5, A plasma processing method characterized in that the desired angle is approximately 90 degrees.

7. In the plasma treatment method described in claim 5, The process further comprises a second step of controlling the electromagnet so that the height from the surface to be processed to the electron cyclotron resonance surface is a desired height. The first step is to control the electromagnet so that the angle of the outer periphery of the surface to be processed is approximately 90 degrees. A plasma processing method characterized in that the electron cyclotron resonance is an electron cyclotron resonance resulting from the interaction between the microwave and the first static magnetic field.

8. In the plasma processing method described in claim 7, The plasma treatment method is characterized in that the first step is a step of controlling the electromagnet so that the angle over the entire surface to be treated is approximately 90 degrees.

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