Plasma processing apparatus and plasma processing method

Abstract

In a plasma processing apparatus using ECR, information including parameters of the position and shape of an ECR surface is used as an input value to a control device of the plasma processing apparatus. Information on the ECR surface shape that can be input from an input device of a plasma processing apparatus to a control device is limited by a separately determined discharge stability reference. When a discharge stabilization reference is satisfied, a plurality of coil current value candidates are extracted from a database including a relationship between a plurality of coil current values and ECR surface shape information, and a plurality of coil current values to be input to a plurality of coils are determined in accordance with a coil current selection reference from the plurality of coil current value candidates.

Description

Technical Field

[0001] The present disclosure relates to a plasma processing device and a plasma processing method, and relates to a plasma processing device for processing a substrate-shaped sample such as a semiconductor wafer arranged in a processing chamber in a vacuum container using plasma formed in the processing chamber, such as etching. Background Art

[0002] The structure of semiconductor devices is becoming increasingly miniaturized and complex in order to balance the improvement of computing power and low power consumption. This requires more complex manufacturing processes and more difficult processing, resulting in higher manufacturing costs for semiconductor devices. In order to reduce manufacturing costs, it is effective to increase the number of high-quality semiconductor devices manufactured from one wafer, and good process uniformity needs to be achieved within the wafer surface.

[0003] Plasma etching, plasma CVD (Chemical Vapor Deposition), plasma ashing and other plasma treatments are widely used in semiconductor device manufacturing. The ECR (Electron Cyclotron Resonance) method, which is a method of generating plasma, generates high-density plasma in the isomagnetic field surface (hereinafter referred to as the ECR surface) generated by ECR. In order to obtain good process uniformity, in a plasma processing device using the ECR method, the position and shape of the ECR surface are adjusted to control the plasma generation position.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: JP Patent No. 6850912 Summary of the invention

[0007] -Problems to be solved by the invention-

[0008] In order to obtain a good processing shape and uniformity in the etching process, the user of the etching device studies various input parameters such as the gas type, gas flow rate, pressure, high-frequency power for plasma generation, and high-frequency power applied to the substrate in each step of the etching process, and inputs them into the recipe. The etching device adjusts various parameters of the etching device based on the input recipe information to perform the etching process. In an etching device using ECR plasma, in order to use a coil to form an ECR surface as a plasma generation area in the plasma processing chamber of the etching device, it is necessary to set the current value of the coil as an input parameter. As an adjustment knob for obtaining a good processing shape and uniformity within the wafer surface, the etching device is equipped with multiple coils, and the combination of currents supplied to each coil is changed to adjust the plasma generation position.

[0009] When multiple coil currents are input, the combinations of the currents vary, and it is difficult for the device user to understand what kind of ECR ​​surface is formed based on only the input current value. Therefore, due to the wrong input of the current value, there are cases where the position and shape of the ECR surface become inappropriate as expected. As an example of inappropriateness, there is a case where the ECR surface contacts a part with low plasma resistance inside the plasma processing chamber. At this time, ion sputtering is sometimes promoted in the area where the ECR surface contacts the surface of the part, and foreign matter is generated due to part loss. Alternatively, when the ECR surface exists in the gap between the parts constituting the etching device, abnormal discharge will occur in the gap. In addition, when the position and shape of the ECR surface are inappropriate, the discharge of the generated plasma becomes unstable, sometimes causing problems in the reproducibility of the processing.

[0010] In order to avoid these situations, a method of limiting the current value of the coil that can be input into the recipe is considered. However, when the current value of the coil is limited to a given range, the use of the ECR surface that originally has no problem in operation may be restricted. In other words, the position and shape of the ECR surface are excessively restricted, and as a result, the processing accuracy and processing uniformity within the chip surface are sometimes not obtained. Patent document 1 proposes a method of measuring the position of the ECR surface using a height monitor. However, in Patent document 1, there is no sufficient research on specifying what shape the ECR surface is when inputting a recipe.

[0011] -Methods for solving the problem-

[0012] The present invention discloses a plasma processing device using ECR, in which information including parameters of the position and shape of the ECR surface is used as an input value to a control device of the plasma processing device. The information of the ECR surface shape that can be input from the input device of the plasma processing device to the control device is limited by a separately determined discharge stability standard. When the discharge stability standard is satisfied, multiple coil current value candidates are extracted from a database including the relationship between multiple coil current values ​​and ECR surface shape information, and multiple coil current values ​​input to multiple coils are determined from the multiple coil current value candidates according to the coil current selection standard.

[0013] -Effects of the Invention-

[0014] According to the present disclosure, the plasma processing device can adjust the position and shape of the ECR surface while avoiding the use of the position and shape of the ECR surface that is likely to cause discharge instability, component loss, and foreign matter generation, thereby achieving plasma processing with good substrate processing accuracy and uniformity within the substrate surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a cross-sectional view of the etching device involved in the first embodiment.

[0016] Figure 2 This is a flowchart related to the first embodiment.

[0017] Figure 3 This is the recipe input screen in the first embodiment.

[0018] Figure 4 This is an enlarged view of the ECR surface shape screen in the first embodiment.

[0019] Figure 5 This is the database of coil current and ECR surface shape information in the first embodiment.

[0020] Figure 6 It is a cross-sectional view of an etching device according to the second embodiment. DETAILED DESCRIPTION

[0021] Hereinafter, the embodiments and examples will be described using the accompanying drawings. However, in the following description, the same components are sometimes marked with the same reference numerals and repeated descriptions are omitted. In addition, in order to make the description clearer, the accompanying drawings are sometimes more schematically represented than the actual method, but they are ultimately an example and do not limit the interpretation of the present invention.

[0022] Example 1

[0023] Figure 1 A cross-sectional view of an etching device 100 involved in a first embodiment of the present disclosure is shown. The etching device (also referred to as a plasma processing device) 100 includes a structure described below. In the following embodiment, the etching device 100 is described as a representative example, but the present disclosure can also be applied to a plasma processing device. The etching device 100 adopts an ECR (Electron Cyclotron Resonance) method as a method of generating plasma, and generates high-density plasma in an isomagnetic field surface (hereinafter referred to as an ECR surface) generated by ECR. In order to obtain good process uniformity, in a plasma processing device that is an etching device 100 using the ECR method, the position and shape of the ECR surface are adjusted to control the generation position and shape of the plasma.

[0024] Microwaves oscillate from a microwave source 1 and are transmitted from an isolator 2, an automatic matching device 3, and a rectangular waveguide tube 4 to a circular waveguide tube 6 via a circular-rectangular converter 5. The microwave source 1 can be, in other words, a unit, a high-frequency power supply, or a microwave supply device that supplies high-frequency power (Radiofrequency power) for microwaves used to generate plasma. In the etching device 100 of this embodiment, microwaves of 2.45 GHz, which are often used in industry, are used. The isolator 2 is used to protect the microwave source 1 from the influence of reflected waves of microwaves, and the automatic matching device 3 is used to adjust the load impedance, suppress reflected waves, and thus effectively supply microwaves. In order to facilitate the processing of microwave propagation phenomena, the size of the waveguide cross section is specified so that only the TE10 mode of the fundamental mode is propagated in the rectangular waveguide tube 4, and only the TE11 mode of the fundamental mode is propagated in the circular waveguide tube 6. The microwave propagates to the cavity 7 and is introduced into the plasma processing chamber 10 through the microwave introduction window 8 and the shower plate 9. The cavity 7 uses a conductor as a material for reflecting microwaves. As the material of the cavity 7, aluminum is used, for example. The plasma processing chamber 10 can also be referred to as a processing chamber or a reaction chamber.

[0025] In order to form a magnetic field required for ECR inside the plasma processing chamber 10, an upper coil 11, a middle coil 12, and a lower coil 13 are provided as a plurality of coils outside the plasma processing chamber 10. An upper coil power supply 14, a middle coil power supply 15, and a lower coil power supply 16 are connected to these coils 11, 12, and 13, respectively. The upper coil power supply 14, the middle coil power supply 15, and the lower coil power supply 16 are provided to allow current (also referred to as coil current) to flow through the coils 11, 12, and 13, respectively. By adjusting the plurality of coil currents (also referred to as plurality of coil current values) supplied to the coils 11, 12, and 13 using the upper, middle, and lower coil power supplies 14 to 16, the position and shape of the ECR surface 17 can be controlled. In other words, the ECR surface 17 can be referred to as an isomagnetic field surface in the magnetic flux density for generating cyclotron resonance of charged particles by interaction with microwaves inside the processing chamber 10.

[0026] In other words, the upper coil 11, the middle coil 12, and the lower coil 13 can be translated as the first coil 11 constituting the electromagnet (first electromagnet) of the upper layer, the second coil 12 constituting the electromagnet (second electromagnet) of the middle layer, and the third coil 13 constituting the electromagnet (third electromagnet) of the lower layer. The upper coil 11, the middle coil 12, and the lower coil 13 can also be regarded as being arranged coaxially (or axially symmetrically) with the central axis of the processing chamber 10 so as to surround the periphery of the processing chamber 10. The central axis of the processing chamber 10 will be described later. In the present embodiment, an example in which the coils 11, 12, and 13 are arranged in three locations, namely, the upper, middle, and lower parts, is shown, but the number of coils can be increased or decreased, and the position can be changed according to the need to control the position and shape of the ECR surface.

[0027] The yoke 18 has a function of preventing the magnetic field from leaking to the outside of the plasma processing chamber 10 , and has a function of adjusting the shape of magnetic lines of force inside the plasma processing chamber 10 .

[0028] In this example, the upper coil 11 is arranged to surround the upper part of the outer side of the processing chamber 10 except the part where the circular waveguide 6 is arranged. The middle coil 12 is arranged to surround the lower side of the upper coil 11 and the upper side part of the outer side of the processing chamber 10. In this example, the middle coil 12 is arranged around the upper side part of the outer side of the processing chamber 10 so as to surround the outer side of the cavity 7 and the microwave introduction window 8. The lower coil 13 is arranged to surround the lower side of the middle coil 12 and the side part of the middle part of the outer side of the processing chamber 10. In this example, the lower coil 13 is arranged around the side part of the middle part of the outer side of the processing chamber 10 between the lower part of the microwave introduction window 8 and the substrate mounting table and high-frequency electrode 24 described later.

[0029] In order to protect the side wall of the plasma processing chamber 10 from the influence of plasma, an inner cylinder 19 is provided inside the side wall of the plasma processing chamber 10. Quartz is used as a material with high plasma resistance for the inner cylinder 19 located near the plasma. Alternatively, yttrium oxide, aluminum oxide, yttrium fluoride, aluminum fluoride, aluminum nitride, etc. can also be used as a material with high plasma resistance.

[0030] Quartz is used as a material that transmits microwaves and is transparent as the material of the microwave introduction window 8 and the shower plate 9. Alternatively, other dielectric materials may be used as long as they are transparent and transmit microwaves.

[0031] Gas is supplied between the microwave introduction window 8 and the shower plate 9 from a gas supply unit (not shown) (also referred to as a gas supply device). The gas supply unit includes a function of supplying a desired flow rate through a mass flow controller. In addition, the type of gas used is appropriately selected according to the film to be processed, etc., and multiple types of gases are supplied at a given flow rate combination. A plurality of gas supply holes 20 are provided in the shower plate 9, and the gas is supplied to the plasma processing chamber 10 via the gas supply holes 20.

[0032] The supplied gas is vacuum-exhausted by a turbomolecular pump 22 via a conductance regulating valve 21. A substrate stage and high-frequency electrode 24 for mounting a substrate 23 to be processed is provided at the lower portion of the plasma processing chamber 10, and an insulating plate 25 is provided at the lower portion thereof, and bias power is supplied to the substrate stage and high-frequency electrode 24 from a bias power supply 26 via an automatic matcher 27. In order to perform the desired etching, the bias power is adjusted to control the energy of the ions incident on the substrate 23 to be processed. Here, the substrate 23 to be processed can be configured, for example, to have a structure to be processed formed on the surface (also referred to as a plane) of the main surface of a semiconductor wafer. In addition, in this specification, the substrate 23 to be processed is sometimes simply referred to as a sample or a wafer. In addition, the substrate stage and high-frequency electrode 24 can also be referred to as a sample stage or a stage.

[0033] In order to obtain the RF (Radio Frequency) supplied to the substrate mounting table and high frequency electrode 24, o In order to ground the high frequency (RF) power (ground potential, ground reference potential), a ground electrode 28 is applied to the lower part of the plasma processing wall. The substrate stage and high frequency electrode 24 is provided with an adsorption mechanism and a temperature control unit for the substrate 23 to be processed (not shown), and the temperature of the substrate to be processed is adjusted as needed. In order to protect the outer periphery of the substrate stage and high frequency electrode 24 from the influence of plasma, a base 29 and a stage cover 30 are provided. Quartz is used as a material with high plasma resistance for the base 29 and the stage cover 30. Plasma based on ECR is generated in the microwave supplied by the microwave source 1 and the ECR surface 17 formed by the upper, middle and lower coils 11, 12, 13, and the ions and radicals generated here are irradiated onto the surface (processed surface) of the substrate 23 to be processed, thereby performing etching.

[0034] In order to achieve the desired etching, the device user specifies various input parameters of the etching device 100. For example, according to the film to be processed, the processing shape to be achieved, etc., the parameters such as gas type and pressure are adjusted. These parameters are specified as a recipe that summarizes the input parameters in the control computer (also called control device) 32 via the graphical user interface 31 as an input device provided by the etching device 100. The etching process outputs control signals from the control computer 32 to various components in the etching device 100 based on the information of the recipe. For example, the control signal from the control computer 32 is output to the upper, middle, and lower coil power supplies 14 to 16, and the current specified by the recipe is output. In other words, the control computer 32 is configured to control the coil power supplies 14 to 16. In addition, although not shown in the figure, the control signal is output to various components provided by each device such as the microwave source 1, the bias power supply 26, the flow conductance adjustment valve 21, and the mass flow controller to control microwave power, RF power, pressure, gas flow, etc.

[0035] In the plasma generation method using ECR, coils (11, 12, 13) are used, so it is necessary to specify the current value of the coils (11, 12, 13) when making a recipe. In order to specify the coil current value of the coils (11, 12, 13), the result of pre-calculating the shape information of the ECR surface 17 by an external computer or the like is studied, and the coil current value is selected and input into the recipe. However, when the device user inputs the numerical value of the coil current value into the recipe, it is impossible to recognize what shape the ECR surface 17 will become only by the numerical value, so sometimes even if the position and shape of the ECR surface 17 are incorrectly input, they will not notice it. As an inappropriate example, for example, when the position of the ECR surface 17 is located in the gap between the parts, there is a possibility that the parts will be worn out due to abnormal discharge between the gaps of the parts. In addition, when the position of the ECR surface 17 contacts a part with low plasma resistance, the part is worn out due to sputtering on the surface of the part, and foreign matter may sometimes be generated depending on the situation. Alternatively, when the ECR surface 17 is formed outside the plasma processing chamber 10, the discharge of the plasma itself becomes unstable, making it difficult to achieve stable etching. In order to avoid such a problem, a method of limiting the coil current value that can be input is considered so that the ECR surface 17 that is originally undesirable will not be formed. There are many combinations of coil current values ​​for the upper, middle, and lower coils 11, 12, and 13, but if the input range of the coil current value is limited, the number of combinations is greatly reduced, and the range of the position and shape of the ECR surface 17 that can be controlled is limited to more than necessary. In other words, there is a problem that the processing accuracy and processing uniformity within the wafer surface that should have been possible without the restriction can no longer be obtained due to the restriction of the coil current.

[0036] Taking these issues into consideration, the plasma processing method involved in this embodiment is designed. Figure 2 The flow chart shown explains the plasma processing method.

[0037] First, in step 33, the user inputs the parameters of the shape information (ECR surface shape information) of the ECR surface 17 to the control computer 32 via the graphical user interface 31. In other words, in step 33, the information of the shape of the isomagnetic surface in the magnetic flux density for generating the cyclotron resonance of the charged particles by the interaction with the microwave is input from the input device 31 to the control computer 32. Step 33 can be said to be a step of using the information of the shape of the isomagnetic surface (ECR surface 17) input from the input device 31 as an input value of the control computer 32.

[0038] The shape information of the ECR surface 17 mentioned here refers to information specifying the position and shape of the ECR surface 17. In the present embodiment, since the coils 11, 12, and 13 form an axisymmetric magnetic field with respect to the central axis of the plasma processing chamber 10, the position and shape of the ECR surface 17 can be considered on a two-dimensional plane in the radial and height directions of the plasma processing chamber 10 of the etching apparatus 100.

[0039] As a method of specifying the position and shape of the ECR surface 17, a method of specifying the position and shape of the ECR surface 17 based on the height of the ECR surface 17 at a plurality of radial positions of the ECR surface 17 may be considered. Figure 1 As shown, the distance in the height direction H1 between the plane of the wafer 23 on the central axis of the device (plasma processing chamber 10) and the ECR surface 17 (hereinafter referred to as the ECR height) and the ECR height H2 of the outer periphery of the device (plasma processing chamber 10) (the outer periphery of the inner wall of the plasma processing chamber 10: the inner wall of the inner cylinder 19 provided on the inner side of the side wall of the plasma processing chamber 10) are specified. In other words, the information (H1, H2) of the shape of the isomagnetic surface, i.e., the ECR surface 17, is constituted to include the distance in the vertical direction (here, two heights: H1, H2) between the isomagnetic surface 17 and the plane of the surface of the wafer 23 at a plurality of positions in the radial direction as viewed from the central axis of the plasma processing chamber 10.

[0040] Alternatively, the shape information of the ECR surface 17 may be specified in other input forms. For example, the curvature of the ECR surface 17, the slope of a certain point on the curve of the ECR surface 17, information on the approximate curve of the ECR surface, etc. may be used. In order to allow the device user to easily create a recipe, the number of parameters specifying the shape of the ECR surface 17 is not too large, and it is preferably set to the minimum number required.

[0041] Here, use Figure 1 The central axis of the plasma processing chamber 10, the radial direction and the height direction of the plasma processing chamber 10, etc. are described. Figure 1The inside of the dotted line 110 depicts a top view and a cross-sectional view of the substrate stage / high frequency electrode 24 and the wafer 23 mounted on the mounting surface of the substrate stage / high frequency electrode 24 in the plasma processing chamber 10. As shown in the top view, when the wafer 23 is being processed, the center point O of the substantially circular wafer 23 overlaps with the center point of the mounting surface of the substrate stage / high frequency electrode 24 and the center point of the plasma processing chamber 10 and is arranged inside the plasma processing chamber 10. In other words, the center point of the mounting surface of the substrate stage / high frequency electrode 24 and the center point of the plasma processing chamber 10 are arranged on the central axis of the plasma processing chamber 10, and the center point O of the wafer 23 is also arranged on the central axis of the plasma processing chamber 10. The axis in the direction perpendicular to the plane of the surface of the wafer 23 passing through the center point O of the wafer 23 is represented as the z-axis. The axis in the radial direction parallel to the plane of the surface of the wafer 23 passing through the center point O of the wafer 23 is represented as the r-axis. The z-axis can be regarded as the central axis of the device (plasma processing chamber 10). The radial direction and the height direction of the plasma processing chamber 10 correspond to the r-axis direction (radial direction) and the z-axis direction (vertical direction), respectively.

[0042] like Figure 1 As shown, the distance H1 in the height direction between the plane of the wafer 23 on the central axis of the device (plasma processing chamber 10) and the ECR surface 17 (hereinafter, the ECR height) is the height of the wafer 23 from the ECR surface 17 at the center point O of the wafer 23, the value of the z-axis in the height direction is H1 (z=H1), and the value of the r-axis in the radial direction is zero: 0 (r=0). In addition, regarding the ECR height H2 of the outer periphery of the device (plasma processing chamber 10), the value of the z-axis is H2 (z=H2), and the value of the r-axis in the radial direction is, for example, rm (r=rm). rm is the distance between the central axis of the plasma processing chamber 10 (the center point O of the wafer 23) and the inner wall of the outer periphery of the plasma processing chamber 10 in the top view (for example, refer to Figure 4 ).

[0043] Next, in step 34, the control computer 32 determines whether the input parameters meet the discharge stability criterion. The discharge stability criterion is a criterion for determining the range of the position and shape of the ECR surface 17 that can be used stably. The criterion is prepared using the results of a preliminary investigation of the stability of the discharge when the shape of the ECR surface 17 is changed, the amount of foreign matter generated, etc. The stability of the discharge can be investigated by confirming the time change of the discharge by observation using a camera and measurement using a probe. For example, as a result of the preliminary evaluation of the discharge stability performed to prepare the discharge stability criterion, when the ECR surface 17 approaches the lower surface of the shower plate 9, a local discharge is generated in the center of the lower surface of the shower plate 9 (the lower surface of the shower plate 9 on the z-axis), causing problems in the plasma treatment. Based on this result, as a discharge stability criterion (first discharge stability criterion), for example, it is stipulated that "ECR heights H1 and H2 are 30 mm or more lower than the distance between the processed substrate 23 (the surface of the processed substrate 23) and the shower plate 9 (the lower surface of the shower plate 9)" (in other words, the ECR heights H1 and H2 are set to be 30 mm or more lower than the lower surface of the shower plate 9). In addition, if the ECR surface 17 is formed in the gap between the inner cylinder 19 and the ground electrode 28, abnormal discharge may sometimes occur in the gap. Therefore, as another discharge stability criterion (second discharge stability criterion), for example, it is stipulated that "ECR height H2 is 30 mm or more higher than the distance between the gap between the inner cylinder 19 and the ground electrode 28 and the processed substrate 23 (the surface of the processed substrate 23)" (in other words, the ECR height H2 is set to be higher than the value obtained by adding 30 mm to the distance between the surface of the processed substrate 23 and the gap between the inner cylinder 19 and the ground electrode 28). Furthermore, one or more other discharge stability criteria may be created based on the shape information of the ECR surface 17 where problems in plasma processing such as conditions where foreign matter is likely to be generated or discharge instability occur.

[0044] In other words, the input range of the information on the shape of the isomagnetic surface (the shape information of the ECR surface 17) input from the input device 31 is limited based on a predetermined criterion (here, the first discharge stability criterion and the second discharge stability criterion). In the case where the input parameters do not meet the discharge stability criterion, re-input is urged to be set to the conditions that meet the discharge stability criterion (in the case of no in step 34, return to step 33). As described later, in fact, in the input screen of the recipe, a display area is set to constitute the input screen so that the shape information of the ECR surface that can be input is visually displayed, thereby reducing the scene of urging re-input. If the discharge stability criterion is met (in the case of "yes" in step 34), transfer to the next step 35.

[0045] In step 35, the control computer 32 confirms whether the shape information of the input ECR surface 17 exists in the DB (database). The DB is stored in advance in the memory device of the control computer 32. The coil current values ​​of the coils 11, 12, and 13 and the shape information of the ECR surface 17 corresponding thereto are stored in the DB. In other words, the information on the correlation between the coil current values ​​of the coils 11, 12, and 13 and the ECR surface 17 is stored in the DB. In the case where the coil current value corresponding to the shape of the input ECR surface 17 does not exist in the DB, re-input is urged to make it an appropriate value (in the case of No in step 35), and the process returns to step 33. All the information on the correlation between the shape information of the ECR surface 17 that satisfies the discharge stability standard and the coil current of the coils 11, 12, and 13 is stored in the DB, so when re-input is urged, the shape of the ECR surface 17 that is obviously deviated from the discharge stability standard is specified. When the input shape of the ECR surface 17 exists in the DB (in the case of “YES” in step 35 ), the process proceeds to the next step 36 .

[0046] Here, in step 35, the control computer 32 determines that the shape of the input ECR surface 17 exists in the DB. It is not necessary that the value of the shape information of the input ECR surface 17 is completely consistent with the value of the DB. In the case of approximately consistent, it can also be considered to exist in the DB. For example, as long as there is data within the range of ±ΔH of the allowable range of the input values ​​of the ECR heights H1 and H2 in the DB. For example, 3mm is used as ΔH. ΔH is determined based on the accuracy of the shape of the ECR surface 17 obtained to achieve the desired etching.

[0047] In step 35, when there are few parameters specified as the shape information of the ECR surface 17 and when the above-mentioned determination criteria have a width, the coil current values ​​of the coils 11, 12, and 13 that realize the shape of the input ECR surface 17 are not necessarily uniquely determined, and there may be multiple coil current values. In other words, step 35 can be translated as a step of extracting a combination of a plurality of coil current values ​​that realize the shape of the isomagnetic surface 17 in accordance with the information (H1, H2) of the shape of the isomagnetic surface 17 from a database DB, wherein the database DB includes a correlation between a plurality of coil current values ​​supplied to the plurality of coils 11, 12, and 13 and the shape of the isomagnetic surface 17. Alternatively, step 35 can be translated as a step in which the control computer 32 obtains a combination of current values ​​supplied to the coils 11, 12, and 13 for forming the shape of the isomagnetic surface input from the input device 31 based on the correlation between the values ​​of the currents supplied to the coils 11, 12, and 13 and the shape of the isomagnetic surface.

[0048] In the next step 36, the control computer 32 uniquely selects or determines one value (a combination of coil current values ​​of the coils 11, 12, 13) from the multiple candidates of coil current values ​​of the coils 11, 12, 13 obtained in step 35 according to the coil current selection criterion. For example, as an example of the coil current selection criterion, a coil current selection criterion determined to minimize the coil power consumption of the coils 11, 12, 13 may be used to uniquely select or determine the combination of coil current values. Alternatively, as another coil current selection criterion, a coil current selection criterion determined to maximize the gradient of the magnetic flux density in the z direction on the ECR plane 17 on the central axis of the device (plasma processing chamber 10) (in other words, to maximize the gradient of the magnetic field on the central axis of the processing chamber 10) may be used to select or determine the combination of coil current values. In addition to the coil current selection criteria described above, a certain judgment criteria that can uniquely determine the coil currents of the coils 11, 12, and 13 may be used, such as "sorting the current values ​​of the upper coil 13 in ascending order and adopting the most advanced condition". In other words, step 36 can be translated as a step of uniquely determining a plurality of coil current values ​​for driving a desired combination of the plurality of coils 11-13 from the combination of coil current values ​​that realizes the shape of the isomagnetic field surface 17 according to the coil current selection criteria. Alternatively, step 36 can be translated as a step of the control computer 32 finding a desired combination of current values ​​from the combination of current values ​​found in step 35 according to the coil current selection criteria. The coil current selection criteria is a criteria created based on the current that minimizes the power consumption of the coil power supply of the coils 11, 12, and 13 and the shape of the isomagnetic field surface input from the input device 31. Alternatively, the coil current selection criteria is a criteria created based on the current that maximizes the gradient of the magnetic field on the central axis of the processing chamber 10 and the shape of the isomagnetic field surface input from the input device 31.

[0049] Finally, in step 37, the control computer 32 performs plasma processing using the coil currents of the coils 11, 12, and 13 selected in step 36. In other words, the plurality of coil power supplies 14 to 16 are controlled so that the plurality of coils (11 to 13) are driven by a desired combination of a plurality of coil current values. In other words, the control computer 32 controls the coil power supplies 14 to 16 so that each current in the desired combination of current values ​​found in step 36 flows. Then, the substrate 23 to be processed is subjected to plasma processing using the desired plasma generated inside the processing chamber 10.

[0050] Here, if Figure 3 The plasma processing method can be described as follows.

[0051] (Step 33): A step of inputting information on the shape of isomagnetic field surfaces in the magnetic flux density for generating cyclotron resonance of charged particles by interaction with microwaves to the control computer 32 from the input device 31,

[0052] (Step 34): A process of determining, by the control computer 32, whether the information on the shape of the isomagnetic field surface input from the input device 31 satisfies the discharge stability standard.

[0053] (Step 35): A process of obtaining, by the control computer 32, a combination of current values ​​of the coils (11, 12, 13) for forming the shape of the isomagnetic field surface input in step 33 based on the correlation (DB) between the current values ​​of the coils (11, 12, 13) and the shape of the isomagnetic field surface,

[0054] (Step 36): A process of obtaining a desired current value combination from the combination of current values ​​of the coils (11, 12, 13) obtained in step 35 by controlling the computer 32 based on the coil current selection reference,

[0055] (Step 37 ): A step of controlling the coil power supplies 14 to 16 by the control computer 32 so that each current in the combination of desired current values ​​found in step 36 flows through the coils ( 11 , 12 , 13 ).

[0056] If the device user inputs the shape information of the ECR surface 17 that meets the discharge stability standard into the recipe, Figure 2 The flowchart automatically converts the shape information of the ECR surface 17 into the coil current values ​​of the coils 11, 12, and 13. The control computer 32 controls the coil power supplies 14 to 16 to generate the coil current values ​​of the coils 11, 12, and 13. By using the coil current values ​​of the coils 11, 12, and 13 to drive the coils 11, 12, and 13, the desired plasma is generated in the plasma processing chamber 10. Thus, the surface (processed surface) of the substrate 23 to be processed, which is mounted on the substrate mounting table and high-frequency electrode 24 in the plasma processing chamber 10, is plasma-processed using the desired plasma. Therefore, according to the etching device 100 involved in this embodiment, the substrate 23 to be processed can be plasma-processed with good substrate processing accuracy and processing uniformity within the substrate surface.

[0057] According to this embodiment, the device user can search for coil current value conditions for coils 11, 12, and 13 that can achieve etching processing accuracy and processing uniformity from processing conditions with stable discharge and low foreign matter generation by simple recipe input.

[0058] Figure 3A structural example of a recipe input screen 38 involved in the first embodiment is shown. The recipe input screen 38 includes a recipe 39 and an ECR surface shape screen 40. The recipe 39 is a table of input parameters to the plasma processing device 100, which is composed of a plurality of steps and has items for inputting parameters in each step. For example, there are setting items such as time, gas type, flow setting, pressure, etc. for each step. The ECR heights H1 and H2 in the table correspond to the shape information of the ECR surface 17. The upper coil, middle coil, and lower coil represent the set currents (coil current values) of the upper coil 11, the middle coil 12, and the lower coil 13, respectively. The coil current values ​​of the coils 11, 12, and 13 are based on the information of the input ECR heights H1 and H2. Figure 2 The combination of coil currents of coils 11, 12, and 13 is determined by the flowchart and automatically input into recipe 39.

[0059] In this embodiment, for simplicity, the set currents of the coils 11, 12, and 13 are displayed on the recipe input screen 38, but usually, the coil currents of the coils 11, 12, and 13 are not values ​​input by the user and are therefore non-displayed settings. The display and non-display settings of the coil current values ​​of the coils 11, 12, and 13 are configured to be selectable at any time on a setting screen not shown.

[0060] In this embodiment, the shape information of the ECR surface 17 is used as an input parameter to the recipe 39. However, if the coil current values ​​of the coils 11, 12, and 13 are directly used as input parameters, the coil current values ​​of the coils 11, 12, and 13 can be edited by setting the setting screen (not shown) so that the coil currents of the coils 11, 12, and 13 can be directly edited. In this case, on the contrary, the ECR heights H1 and H2 in the recipe 39 are not parameters that can be edited by the user, so the ECR heights H1 and H2 can also be changed to non-displayed settings.

[0061] When a cell is edited in the recipe 39, the shape of the ECR surface 17 in the step to which the cell belongs is output to the ECR surface shape screen 40. The ECR surface shape screen 40 depicts a cross-sectional view of the plasma processing chamber device 10 and the ECR surface 17. The ECR surface 17 is formed according to the information of the ECR heights H1 and H2 input to the recipe. Figure 2 Alternatively, when the coil current values ​​of the coils 11, 12, 13 are used as input parameters, the ECR surface 17 at that time is displayed.

[0062] Figure 4 yes Figure 3 An enlarged view of the ECR surface shape screen 40. Figure 4In the embodiment, the area of ​​the ECR surface 17 that cannot be used is visualized as a prohibited area 41 of the ECR surface 17 based on the discharge stability criterion that "ECR heights H1 and H2 are at least 30 mm lower than the distance between the processed substrate 23 and the shower plate 9" and "ECR height H2 is at least 30 mm higher than the distance between the gap between the inner cylinder 19 and the ground electrode 28 and the processed substrate 23". The device user can refer to the prohibited area 41 of the ECR surface 17 and input an appropriate ECR surface 17. In other words, the erroneous input of the recipe and the inappropriate use of the ECR surface 17 are avoided. In addition, the screen layout of the recipe input screen 38 is not limited to the screen layout described in the present embodiment as long as the function is the same as that described in the present embodiment.

[0063] Figure 5 A configuration example of DB involved in this embodiment is shown. In DB, code 49 is recorded, and corresponding to the code number recorded in code 49, information on upper coil current 50, middle coil current 51, lower coil current 52 supplied to upper coil 11, middle coil 12, and lower coil 13 and corresponding ECR heights H1 (53) and H2 (54), the gradient of magnetic flux density in the z direction on the central axis of the device (the central axis of the plasma processing chamber 10), that is, magnetic field gradient 55, power consumption 56 of the coil, and ECR height 57 at each radial position is recorded. In DB, currents 50, 51, 52 of the upper, middle, and lower coils 11 to 13 are comprehensively recorded within a settable range. DB is not limited to the parameters shown above, and may include parameters related to the shape information of the ECR surface 17, or may not include unnecessary parameters.

[0064] Example 2

[0065] use Figure 6 The plasma processing device according to the second embodiment is described. Figure 1 In the plasma processing apparatus 101 shown in FIG. 1 , a camera 42 for observing the plasma inside the plasma processing chamber 10 is newly connected above the cavity 7. The plasma processing apparatus 101 is similar to the plasma processing apparatus 101 shown in FIG. 1 , except for the camera 42. Figure 1 Since the plasma processing apparatus 100 described in , is the same as that described in , duplicate descriptions are omitted. The camera 42 can also be called a measuring device for measuring the position of the isomagnetic field surface (ECR surface 17).

[0066] The camera 42 confirms the flicker of the plasma discharge and is used to determine the processing conditions of unstable discharge. For example, when making a discharge stability benchmark, the conditions of the ECR surface 17 with stable discharge can be determined based on the information of the camera 42. In the measurement of discharge instability for making a discharge stability benchmark, it is preferred to use non-invasive measurement of optical information such as the camera 42, but it is also possible to measure the conditions of unstable discharge by invasive means such as a probe to make a discharge stability benchmark. In the first embodiment, the case where the discharge stability benchmark is determined by the shape information of the ECR surface 17 and the positional relationship of the parts is described. However, the conditions of unstable discharge are also affected by parameters other than the positional relationship of the parts such as the pressure and gas type supplied to the plasma processing device 101, so it is preferred to investigate the relationship between these parameters and the shape of the ECR surface 17 to make a discharge stability benchmark. In other words, the shape of the ECR surface 17 that can be input and determined by the discharge stability benchmark can also be a benchmark that changes according to parameters such as pressure and gas type. However, since the number of parameters that can be specified in the recipe is huge, it is unrealistic to investigate the discharge stability of all combinations to make a discharge stability benchmark. For example, the discharge stability of the processing conditions may be acquired as learning data by the camera 42, and machine learning and regression analysis may be performed to create a model predicting at what recipe the discharge will be unstable, and the discharge stability criterion may be determined based on the model.

[0067] By observing the region with strong light emission by the camera 42, the position of the ECR surface 17 can be estimated. The position of the ECR surface 17 may deviate from the position assumed in the calculation due to important factors such as the deviation of the magnetic characteristics of the yoke 18, the error in the device assembly, and the error of the output current value of the coil power supply 14, 15, 16. When the position and shape of the ECR surface 17 to be realized in the calculation deviate from the position and shape of the ECR surface 17 measured by the camera 42, the deviation amount is fed back to the control computer 32. The control computer 32 corrects the coil current of the coils 11 to 13 so that the position and shape of the measured ECR surface 17 are consistent with the information (H1, H2) of the position and shape of the isomagnetic surface (ECR surface 17) input by the recipe. In other words, the control computer 32 corrects the coil current values ​​of the coils 11 to 13 output from the plurality of coil power supplies 14, 15, 16 so as to reduce the difference between the position and shape of the isomagnetic surface (ECR surface 17) input from the input device 31 and the position and shape of the isomagnetic surface actually measured by the camera 42.

[0068] By performing such coil current correction, it is possible to eliminate the machine differences among the plurality of plasma processing apparatuses 101. That is, in the plurality of plasma processing apparatuses 101, the same processing can be realized with the same recipe.

[0069] Industrial Applicability

[0070] The present invention can be applied to a plasma processing apparatus that processes a sample on a substrate such as a semiconductor wafer by etching or the like.

[0071] -Description of Reference Numerals-

[0072] 1: microwave source, 2: isolator, 3: automatic matching device, 4: rectangular waveguide, 5: round-rectangular converter, 6: round waveguide, 7: cavity, 8: microwave introduction window, 9: shower plate, 10: plasma processing chamber, 11: upper coil, 12: middle coil, 13: lower coil, 14: upper coil power supply, 15: middle coil power supply, 16: lower coil power supply, 17: ECR surface, 18: yoke, 19: inner cylinder, 20: gas supply hole, 21: flow conductance adjustment throttle valve, 22: turbomolecular pump, 23: processed substrate, 24: substrate mounting table and high-frequency electrode (sample table), 25: insulating plate, 26: bias power supply, 27: automatic matcher, 28: ground electrode, 29: base, 30: mounting table cover, 31: graphical user interface (input device), 32: control computer (control device), 38: recipe input screen, 39: recipe, 40: ECR surface shape screen, 41: prohibited area of ​​ECR ​​surface, 42: camera.

Claims

1. A plasma processing device, comprising: a processing chamber for performing plasma processing on a sample; a high-frequency power supply for supplying high-frequency power of microwaves for generating plasma; a plurality of coils for forming a magnetic field in the processing chamber; a coil power supply for passing a current through each of the coils; a sample stage for placing the sample; and a control device for controlling the coil power supply. The plasma processing device is characterized in that: The control device performs the following processing: information on the shape of isomagnetic field surfaces in the magnetic flux density for generating cyclotron resonance of the charged particles by interaction with the microwaves is input, Based on the correlation between the current value and the shape of the isomagnetic field surface, a combination of current values ​​for forming the shape of the input isomagnetic field surface is obtained. According to the coil current selection standard, a desired current value combination is obtained from the combination of current values ​​obtained. The coil power supply is controlled so that each current in the desired current value combination obtained flows.

2. The plasma processing device according to claim 1, characterized in that: The input range of the input information on the shape of the isomagnetic field surface is limited based on a predetermined standard.

3. The plasma processing device according to claim 1, characterized in that: The input information on the shape of the isomagnetic field surface includes distances between the isomagnetic field surface and the sample at a plurality of positions in the radial direction of the processing chamber.

4. The plasma processing device according to claim 1, characterized in that: The control device corrects the value of the current so as to reduce the difference between the shape of the isomagnetic field surface actually measured by the measuring device and the shape of the input isomagnetic field surface.

5. The plasma processing device according to claim 1, characterized in that: The coil current selection criterion is a criterion created based on the current that minimizes the power consumption of the coil power supply and the shape of the input isomagnetic field surface.

6. The plasma processing device according to claim 1, characterized in that: The coil current selection standard is a standard created based on the current that maximizes the gradient of the magnetic field on the central axis of the processing chamber and the shape of the input isomagnetic field surface.

7. A plasma processing method, using a plasma processing device, the plasma processing device comprising: a processing chamber for performing plasma processing on a sample; a high-frequency power supply for supplying high-frequency power of microwaves for generating plasma; a plurality of coils for forming a magnetic field in the processing chamber; a coil power supply for passing current through each of the coils; and a sample stage for placing the sample. The plasma treatment method is characterized by: a step of inputting information on the shape of an isomagnetic field surface in a magnetic flux density for generating cyclotron resonance of charged particles through interaction with the microwave; A step of obtaining a combination of current values ​​for forming the shape of the input isomagnetic field surface based on a correlation between the current value and the shape of the isomagnetic field surface; A step of obtaining a desired combination of current values ​​from the obtained combinations of current values ​​based on a coil current selection reference; and and controlling the coil power supply so that each current in the desired current value combination obtained flows.

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