Plasma processing apparatus and plasma processing method

Abstract

Provided are plasma processing equipment and a plasma processing method which are capable of measuring reflected light reflected from a region to be processed, regardless of the pattern layout of a device. This plasma processing equipment includes: a light irradiation unit that has a plurality of irradiators which emit light toward different positions on the surface of a wafer placed on a sample stage; a light receiving unit that receives reflected light, which is the light emitted from the plurality of irradiators and reflected by the wafer; and a processing amount detection unit that detects the processing amount of the wafer on the basis of information obtained from the reflected light received by the light receiving unit during processing of the wafer. The processing amount detection unit selects an irradiator for performing light irradiation from among the plurality of irradiators on the basis of the difference between information on each reflection position of the wafer at which the light emitted from each of the plurality of irradiators is reflected and information on a processing position of the wafer, and detects the processing amount of the wafer using the thus-selected irradiator.

Description

Technical Field

[0001] The technology of the present disclosure relates to a plasma processing apparatus and a plasma processing method using the same.

Background Art

[0002] A semiconductor device has, for example, various components and wirings for interconnecting them on the surface of a wafer. Such a semiconductor device is formed by repeating film formation of various materials such as conductors, semiconductors, and insulators, and removal processing of unnecessary portions.

[0003] As a process for removing unnecessary portions, dry etching using plasma is widely used. In plasma etching, a gas introduced into the processing chamber of an etching apparatus is converted into plasma by a high-frequency power source or the like, and etching is performed by exposing the wafer to the plasma-converted gas.

[0004] Anisotropic etching or isotropic etching is performed by sputtering with ions in the plasma or chemical reaction with radicals. By properly using these etchings, components and wirings having various structures can be formed on the surface of the wafer.

[0005] When the processed shape of the wafer by plasma etching is different from the design, the various components formed cannot realize their functions. Therefore, many technologies related to a process monitor for monitoring and stabilizing the etching process of the wafer have been proposed.

[0006] For example, a process monitor that measures the reflected light from the wafer during the etching process to measure the thickness of the film formed on the wafer and the depth of the grooves and holes formed on the wafer is also called a film thickness / depth monitor and is used for end point determination of the etching process and the like. Hereinafter, the film thickness / depth monitor will be abbreviated as a film thickness monitor.

[0007] Patent Document 1 describes a method for improving processing accuracy using a film thickness monitor. More specifically, Patent Document 1 describes a method of using a film thickness measuring device equivalent to a thick film monitor with plasma light as the light source to detect the timing just before the film to be processed is completely removed, thereby terminating the etching process, and then switching to conditions that highly selectively etch the processed area and the non-processed area to perform the etching process.

[0008] Furthermore, Patent Document 2 describes a technique for improving the accuracy of measuring film thickness and depth using a film thickness monitor. More specifically, Patent Document 2 describes that by using an external light source instead of plasma light as the light source irradiated onto the wafer, fluctuations in the light source are reduced, enabling highly accurate measurement of film thickness and depth. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2006-119145 [Patent Document 2] Special Publication No. 2004-507070 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] In semiconductor device manufacturing, various electronic circuits and wiring are formed on the wafer, and the boundaries between devices are formed in a specific layout to create devices that achieve the desired functions. For example, memory devices include a memory section responsible for data storage and circuit sections that store and erase data in that memory. Logic devices include an arithmetic section responsible for digital data calculations and a memory section that temporarily stores calculation results. The layout of these electronic circuit sections and device boundaries varies depending on the device. Hereafter, these layouts on the wafer will be collectively referred to as pattern layouts.

[0011] Because pattern layouts vary, it is preferable to measure the reflected light reflected from the processing area being worked on in order to perform endpoint determination using a film thickness monitor during the device manufacturing process and to achieve high-precision processing. For example, in the memory cell formation process of a memory device, it is preferable to acquire the reflected light from the memory cell portion, which is the processing area, rather than from the device boundary or the data recording / erasing circuit portion.

[0012] In a film thickness monitor that irradiates a wafer with light from an external light source via a light irradiation port (also called an irradiator) and measures the reflected light received via a light measurement port (also called a light receiving unit), if the positions of the light irradiation port and the light measurement port are fixed, the position on the wafer where the reflected light is measured is uniquely determined and becomes a fixed position. Specifically, the position where the perpendicular bisector of the line segment connecting the two ports intersects the wafer becomes the center of the monitor position where the reflected light is measured.

[0013] When using a film thickness monitor with fixed positions for the light irradiation port and the light measurement port, it is difficult to constantly measure the reflected light reflected from the processing area of ​​the wafer during the manufacturing process of devices with various pattern layouts. Therefore, depending on the pattern layout of the device on the wafer, the accuracy of measuring the film thickness and depth on the wafer using the film thickness monitor may decrease, making it difficult to perform highly accurate endpoint determination using the film thickness monitor.

[0014] The technology disclosed herein has been developed in view of these circumstances and aims to provide a plasma processing apparatus and a plasma processing method that can measure reflected light reflected in a processing area, regardless of the pattern layout of the device. [Means for solving the problem]

[0015] A representative example of the technologies disclosed herein is a plasma processing apparatus comprising a processing chamber inside a vacuum vessel and a sample stage placed in the processing chamber on which a wafer to be processed is placed on its upper surface, the apparatus comprising: a light irradiation unit having a plurality of irradiators that irradiate light at different positions toward the surface of the wafer placed on the sample stage; a light receiving unit that receives reflected light reflected by the wafer from the plurality of irradiators; and a processing amount detection unit that detects the amount of processing of the wafer based on information obtained from the reflected light received by the light receiving unit during the processing of the wafer, wherein the processing amount detection unit determines which irradiator to use from among the plurality of irradiators based on the difference between information on each reflection position of the wafer to which the light irradiated from each of the plurality of irradiators is reflected and information on the processing position of the wafer, and detects the amount of processing of the wafer using the determined irradiator. [Effects of the Invention]

[0016] The effects obtained by representative technologies of this disclosure can be briefly explained as follows: According to the technologies of this disclosure, it is possible to always measure reflected light from the processing area regardless of the wafer pattern layout. As a result, highly accurate film thickness measurement and endpoint determination can be achieved. Consequently, highly accurate processing of devices can be achieved. Other issues, configurations, and effects will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0017] [Figure 1] This figure shows the overall configuration of the plasma processing apparatus according to Embodiment 1. [Figure 2] This figure shows the schematic configuration of a wafer processing machine according to Embodiment 1. [Figure 3] This diagram schematically shows the configuration of the optical system according to Embodiment 1. [Figure 4] This figure schematically shows an example of a wafer pattern layout in Embodiment 1. [Figure 5] This diagram shows the functional block of the processing amount calculation unit according to Embodiment 1. [Figure 6A] It is a diagram showing the spectrum of the reflected light from the electronic circuit part of the wafer in Embodiment 1. [Figure 6B] It is a diagram showing the spectrum of the reflected light from the peripheral part of the wafer in Embodiment 1. [Figure 7] It is a diagram schematically showing the positional relationship between the light irradiation part and the light receiving part according to Embodiment 2. [Figure 8] It is a diagram showing the processing position and the monitor position of the wafer in Embodiment 2. [Figure 9] It is a diagram schematically showing the positional relationship between the light irradiation part and the light receiving part according to Embodiment 3. [Figure 10] It is a diagram showing an example of the processing position and the monitor position of the wafer in Embodiment 3. [Figure 11] It is a diagram showing the spectrum of the reflected light obtained by the trial irradiation in Embodiment 4. [Figure 12] It is a diagram showing an example of the calculation result of the error value between the spectrum of the reflected light at each monitor position and the reference spectrum in Embodiment 6.

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the technology of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same parts are generally denoted by the same reference numerals, and repeated explanations are omitted. In the drawings, the representation of the components may be schematically shown with respect to the width, thickness, shape, etc. of each part compared to the actual aspect in order to facilitate the understanding of the invention, but this is merely an example and does not limit the interpretation of the present disclosure.

[0019] (Embodiment 1) FIG. 1 is a diagram showing an outline of the overall configuration of the plasma processing apparatus according to Embodiment 1. FIG. 2 is a diagram showing an outline of the configuration of the wafer processor according to Embodiment 1. FIG. 3 is a diagram schematically showing the configuration of the optical system according to Embodiment 1.

[0020] As shown in Figure 1, the plasma processing apparatus 100 according to this embodiment includes a wafer processing unit 200 that performs etching (plasma processing) on ​​a wafer 500 to be processed, and a processing amount measuring unit 300 that measures the amount of wafer 500 processed (etched amount) by the wafer processing unit 200.

[0021] <Wafer Processing Machine> First, the general configuration of the wafer processing machine 200 will be described. In this embodiment, the wafer processing machine 200 uses a microwave electric field as the electric field for forming plasma, generates an ECR (Electron Cyclotron Resonance) between the microwave electric field and magnetic field to form plasma, and uses the plasma to etch a processing target such as a semiconductor wafer (hereinafter simply referred to as a wafer). In other words, the wafer processing machine 200 can also be called a plasma etching device.

[0022] As shown in Figure 2, the wafer processing unit 200 has a container, such as a vacuum container 205, which has a processing chamber 203 inside where plasma 201 is formed. Below the space where the plasma 201 is formed in the processing chamber 203, a sample stage 207 is positioned on which the wafer 500 to be processed is placed.

[0023] The upper part of the processing chamber 203 is closed by, for example, a disc-shaped dielectric window member 209. Below the window member 209 is a shower plate 211 which forms the circular ceiling surface of the processing chamber 203. The shower plate 211 has a disc shape with a plurality of gas introduction holes 211a that penetrate through the center, and etching gas is introduced into the processing chamber 203 through the gas introduction holes 211a.

[0024] An exhaust port 213 connected to a processing chamber 203 is provided at the bottom of the vacuum vessel 205. Below the processing chamber 203, a vacuum pump 215, such as a turbomolecular pump, is provided for exhausting the gas inside the processing chamber 203 and reducing the pressure, and an exhaust volume control valve 217 is provided to adjust the exhaust flow rate or speed by increasing or decreasing the area of ​​the flow path.

[0025] Above the vacuum vessel 205, an electric field / magnetic field generating unit 219 is positioned to form electric and magnetic fields for generating plasma 201 within the processing chamber 203. The electric field / magnetic field generating unit 219 comprises a waveguide 221 and an electric field generating power supply 223. A high-frequency electric field oscillated from the electric field generating power supply 223 is transmitted through the inside of the waveguide 221 and introduced into the processing chamber 203.

[0026] Magnetic field generating coils 225 are positioned around the lower end of the waveguide 221 and around the vacuum vessel 205. Each magnetic field generating coil 225 consists of an electromagnet and a yoke to which a direct current is supplied to form a magnetic field.

[0027] In a wafer processing machine 200 with this configuration, microwaves are emitted from the electric field generating power supply 223 while processing gas is introduced into the processing chamber 203 through the gas introduction hole 211a of the shower plate 211. The microwave electric field is supplied to the processing chamber 203 from above downwards, passing through the window member 209 and the shower plate 211. Furthermore, a magnetic field generated by the DC current supplied to the magnetic field generating coil 225 is supplied into the processing chamber 203, interacting with the microwave electric field and generating an ECR. This ECR excites, dissociates, or ionizes atoms or molecules of the processing gas, generating a high-density plasma 201 in the processing chamber 203. The semiconductor wafer 500 placed on the sample stage 207 is then etched (plasma processed) by the plasma 201.

[0028] <Overall Control Section> Furthermore, as shown in Figure 1, the plasma processing apparatus 100 includes an overall control unit 150 that comprehensively controls the operation of the plasma processing apparatus 100.

[0029] The overall control unit 150 consists of, for example, an arithmetic unit such as a CPU (Central Processing Unit), a RAM (Random Access Memory) unit such as semiconductor memory, a storage unit such as an SSD (Solid State Drive) or HDD (Hard Disk Drive), a communication unit, and so on. The overall control unit 150 may also utilize a PLD (Programmable Logic Device) such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array) instead of a CPU.

[0030] The overall control unit 150 controls the operation of the wafer processing unit 200, which is a plasma etching device, as one of the controls for the plasma processing apparatus 100. The overall control unit 150 performs tasks such as introducing gas into the processing chamber 203, generating and controlling the plasma 201, and applying voltage to the wafer 500 using a high-frequency power supply (not shown). In other words, the overall control unit 150 performs synchronization and timing adjustments between each device in the processing chamber 203 so that the desired etching process on the wafer 500 is achieved.

[0031] Furthermore, when the plasma 201 is pulsed, this pulsed state is also controlled by the overall control unit 150. At this time, the On / Off state is switched by modulation such as voltage application from a high-frequency power supply or microwave irradiation to convert the etching gas into plasma, causing the plasma 201 to be pulsed. The plasma 201 can also be pulsed by modulation of the etching gas introduction time.

[0032] <Processing volume measuring device> As mentioned above, the plasma processing apparatus 100 is equipped with a processing amount measuring instrument 300 that measures the processing amount (etching amount) of the wafer 500 by the wafer processing unit 200. This processing amount measuring instrument 300 can also be called a film thickness monitor, as it measures the thickness of the film deposited on the wafer 500 and the depth of grooves and holes formed on the wafer 500.

[0033] The processing amount measuring device 300 includes a light source unit 310, an optical system 320, and a detection unit 330. These light source unit 310, optical system 320, and detection unit 330 are, for example, arranged within a cavity 227, which is the space between the waveguide 221 and the window member 209 of the wafer processing device 200 described above. For example, the optical system 320 is arranged on the window member 209.

[0034] The light source unit 310 emits continuous light from ultraviolet to infrared. However, if the processing amount measuring instrument 300 measures the processing amount, in other words, measures the film thickness and depth, using a specific wavelength, the light source unit 310 only needs to emit a light source of that specific wavelength.

[0035] The light emitted from the light source unit 310 is introduced into the processing chamber 203 via the optical system 320 and irradiated onto the semiconductor wafer 500 as irradiation light 311.

[0036] More specifically, the optical system 320 includes a light irradiation unit (also called a multi-point irradiation port) 321, as shown in Figure 3. The light irradiation unit 321 is composed of multiple irradiators (also called irradiation optical ports) 323 for irradiating the processing chamber 203 with light emitted from the light source unit 310 as irradiation light 311.

[0037] Furthermore, the multiple irradiators 323 are arranged above the processing chamber 203 (for example, within the cavity 227) as described above, and are positioned at different locations in the in-plane direction of the wafer 500. As an example, the multiple irradiators 323 are arranged in a line in the radial direction of the wafer 500.

[0038] Each irradiator 323, although not shown in the figure, is configured to include a collimator lens and an optical fiber connecting the collimator lens to the light source unit 310. When irradiating the wafer 500 with irradiation light 311, the light emitted by the light source unit 310 is introduced into one or more specific optical fibers. As a result, the irradiation light 311 is irradiated onto the wafer 500 via one or more irradiators 323.

[0039] The switching of the optical input from the light source unit 310 to each irradiator 323 is performed by a fiber switch or the like (not shown). Furthermore, the configuration of the irradiator 323 is not particularly limited as long as it can irradiate the wafer 500 in the processing chamber 203 with the light emitted from the light source unit 310 as irradiation light 311.

[0040] Furthermore, although this embodiment describes an example in which multiple irradiators 323 are arranged linearly on a plane parallel to the wafer 500, the arrangement of each irradiator 323 is not limited to this. Each irradiator 323 may be arranged, for example, in a two-dimensional plane or in three-dimensional space above the wafer 500.

[0041] Furthermore, the optical system 320 includes at least one light receiving unit (light receiving port) 325 for inputting the reflected light 312 reflected by the wafer 500 to the detection unit 330. In this embodiment, the optical system 320 includes one light receiving unit 325. This light receiving unit 325, although not shown in the figures, consists of a collimator lens and an optical fiber connecting the collimator lens and the detection unit 330.

[0042] The optical system 320 may include multiple light-receiving units 325. In this case, each light-receiving unit 325 is configured with a collimator lens and an optical fiber. Furthermore, in detecting the reflected light 312 from the wafer 500, the light received by a specific light-receiving unit 325 is input to the detection unit 330. That is, the light from a specific optical fiber constituting the light-receiving unit 325 is input to the detection unit 330.

[0043] Here, the reflected light 312 detected by the detection unit 330 is the light reflected from the wafer 500 at the point where the perpendicular bisector of the line connecting the irradiator 323 that is emitting light and the light receiving unit 325 connected to the detection unit 330 intersects the wafer 500. The reflection position of the reflected light 312 input to the light receiving unit 325 on the wafer 500 will be called the "monitoring position".

[0044] In this embodiment, the processing amount measuring device 300 is exemplified as having independent light source units 310 and an optical system 320, but the configuration of the processing amount measuring device 300 is not limited to this. In the processing amount measuring device 300, the light source unit 310 may be integrated with the optical system 320. For example, each of the irradiators 323 in the optical system 320 may be equipped with an LED that serves as a light source. In this case, in the processing amount measuring device 300, the light source unit 310 is included in the optical system 320.

[0045] Furthermore, in order to efficiently irradiate the wafer 500 with the irradiation light 311, each irradiator 323 may be configured to combine an LED and a collimator lens.

[0046] Furthermore, the processing amount measuring instrument 300 may also include, for example, a display-type light source having a specific size and number of pixels as a light irradiation unit 321. In this case as well, the light source unit 310 is included in the optical system 320.

[0047] The detection unit 330, for example, includes a spectrometer to spectrally analyze the introduced light and detect the amount of light for each wavelength. When measuring the processing amount of the wafer 500 (film thickness and depth on the wafer 500) using a specific wavelength, the detection unit 330 may be configured to include a photodetector or the like, not just a spectrometer.

[0048] Furthermore, in this case, if the light introduced into the detection unit 330 is only of a desired specific wavelength, the detection unit 330 only needs to consist of a photodetector. Also, if continuous light is introduced, the detection unit 330 should be equipped with a device that selects only specific wavelengths, such as a monochromator, prior to the photodetector.

[0049] The detection unit 330 continuously detects light at regular intervals, for example, 2 Hz or 10 Hz, during the plasma processing of the wafer 500. The detection data detected by the detection unit 330 is then transmitted to the processing amount detection unit 340.

[0050] The processing amount detection unit 340, like the overall control unit 150, is composed of, for example, a calculation unit such as a CPU, a RAM unit, a storage unit, a communication unit, etc., and performs calculations of the processing amount (etching amount) of the wafer 500. In this embodiment, the processing amount detection unit 340 includes a processing position information acquisition unit 341, an optical system condition determination unit 343, and a processing amount calculation unit 345.

[0051] The processing position information acquisition unit 341 acquires information (hereinafter also referred to as processing position) regarding the processing position (also referred to as processing position) of the wafer 500 to be processed. For example, the processing position information acquisition unit 341 acquires the processing position information of the wafer 500 from a processing information management unit (not shown) prior to etching.

[0052] Here, information regarding the processing position of the wafer 500 refers to, for example, the coordinates of the processing position in the pattern layout of the wafer 500, or the coordinates that identify the processing target area including the processing position.

[0053] Figure 4 is a schematic diagram showing an example of the wafer pattern layout in Embodiment 1. As shown in Figure 4, the wafer 500 to be processed has individual patterns 505, which include an electronic circuit section 501 and its peripheral section 503, as its pattern layout. These individual patterns 505 are repeated on the wafer 500.

[0054] For example, the size of the electronic circuit section 501 is approximately 5 mm in height and 15 mm in width. The size of the individual pattern 505, that is, the size to the boundary between adjacent individual patterns 505, is approximately 30 mm in height and 30 mm in width.

[0055] Within the individual patterns 505 of the wafer 500, the etching process is performed on the electronic circuit sections 501. In other words, in the example shown in Figure 4, the electronic circuit sections 501 are the processing location or the area to be processed.

[0056] Therefore, the information supplied from the processing position information acquisition unit 341 to the optical system condition determination unit 343 is the coordinates of the processing positions within the electronic circuit unit 501. For example, the processing position information acquisition unit 341 supplies the optical system condition determination unit 343 with coordinate information of processing positions P11 to P14 within each electronic circuit unit 501.

[0057] The processing positions P11 to P14 can be set to any position within the electronic circuit section 501, but it is preferable that they be set near the center of the electronic circuit section 501.

[0058] The information acquired by the processing position information acquisition unit 341 is supplied to the optical system condition determination unit 343. Based on the processing position information on the wafer 500 supplied by the processing position information acquisition unit 341, the optical system condition determination unit 343 determines the conditions of the optical system 320.

[0059] The optical system condition determination unit 343 determines which irradiator 323 to irradiate the wafer 500 based on the difference between the information of each reflection position (monitor position) on the wafer 500 where light irradiated from each of the multiple irradiators 323 is reflected and the information of the processing position on the wafer 500, as one of the conditions for the optical system 320, and detects the amount of processing on the wafer 500 using the determined irradiator 323.

[0060] In this embodiment, the optical system condition determination unit 343 selects from among the plurality of irradiators 323 described above that the distance between the reflection position (monitor position) on the wafer 500 where the light irradiated from the irradiator 323 is reflected and the processing position on the wafer 500 is closer than a preset distance. The preset distance can be set arbitrarily, but it is preferable to set it to the shortest possible distance.

[0061] The optical system condition determination unit 343 determines the conditions of the optical system 320 by comparing the coordinates that identify the processing position or processing target area of ​​the wafer 500 transmitted from the processing position information acquisition unit 341 with the coordinates of the monitor position that can be selected in the optical system 320.

[0062] For example, in Figure 3, reflected light 312A is the irradiation light 311A ​​emitted from the irradiator 323 furthest from the light receiving unit 325 and reflected by the wafer 500. Reflected light 312B is the irradiation light 311B emitted from the irradiator 323 closest to the light receiving unit 325 and reflected by the wafer 500.

[0063] As can be seen from this figure, by changing the position of light irradiation in the light irradiation unit 321, that is, by changing the irradiator 323 used, the reflection position (monitoring position) of the reflected light 312 received by the light receiving unit 325 on the wafer 500 changes.

[0064] Furthermore, in the example shown in Figure 3, twelve irradiators 323 are arranged at intervals of approximately 10 mm. In this case, by switching the irradiator 323 that emits light, the monitoring position of the reflected light 312 detected by the light receiving unit 325 can be controlled at intervals of approximately 5 mm. In other words, the optical system condition determination unit 343 can determine the desired irradiator 323 from multiple irradiators 323 with different monitoring positions at intervals of approximately 5 mm.

[0065] In this embodiment, the optical system condition determination unit 343 identifies, for example, the monitor position with coordinates closest to the processing position of the wafer 500, and determines the irradiator 323 corresponding to the identified monitor position.

[0066] As an example, let's assume that there are selectable monitor positions P21 to P26 within the individual pattern 505, as shown in Figure 4. In this case, the optical system condition determination unit 343 extracts the combination of the coordinates of the processing positions P11 to P15, which are processing position information, and the coordinates of the monitor positions P21 to P25, which are the closest in distance. In this example, the combination of monitor position P21 and processing position P11, and the combination of monitor position P24 and processing position P13 are extracted. The optical system condition determination unit 343 then selects either monitor position P21 or monitor position P24 and determines the irradiator 323 corresponding to the selected monitor position.

[0067] Furthermore, as described above, if the processing position information acquisition unit 341 supplies coordinate information for multiple processing positions P11 to P14, the optical system condition determination unit 343 may identify the monitor position closest to each of the coordinates of each processing position P11 to P14, and determine one or more irradiators 323 to perform light irradiation so that each of the identified monitor positions is used.

[0068] Furthermore, if the optical system 320 includes multiple light-receiving units 325, and the monitor position on the wafer 500 changes depending on the selection of the light-receiving unit 325, the optical system condition determination unit 343 may also be configured to select and determine the light-receiving unit 325 in conjunction with the irradiator 323.

[0069] Furthermore, for example, if the processing position information of the wafer 500 is coordinates that identify the processing target area, the optical system condition determination unit 343 may determine a plurality of irradiators 323 corresponding to a plurality of monitor positions included in the processing target area as the irradiators 323 that perform light irradiation.

[0070] The conditions of the optical system 320 determined by the optical system condition determination unit 343 are supplied to the processing amount calculation unit 345.

[0071] The processing amount calculation unit 345 calculates the processing amount (etching amount) of the wafer 500 using a specific irradiator 323 based on the information supplied from the optical system condition determination unit 343. The processing amount calculation unit 345 controls the state of the optical system 320, for example, to irradiate the wafer 500 with irradiation light 311 from the specific irradiator 323 and receives the reflected light 312 with the light receiving unit 325. Then, the processing amount calculation unit 345 calculates the processing amount (etching amount) of the wafer 500 based on the detection results introduced from the detection unit 330.

[0072] Figure 5 shows the configuration of the functional blocks of the processing amount calculation unit according to Embodiment 1, in particular the functional block that calculates the processing amount of wafers.

[0073] As shown in Figure 5, the time-series data D1 of the light intensity at each wavelength, which is introduced from the detection unit 330 to the processing amount calculation unit 345, is first processed by the digital signal processing unit 3451 to remove and correct various noises and fluctuations, and then supplied to the waveform comparator 3452 as time-series data D2.

[0074] To remove noise in the time domain for each wavelength, for example, a low-pass filter is used. Alternatively, to remove the light intensity offset for each wavelength and observe the time variation of light intensity, signal processing can be used to calculate the change in light intensity or the derivative value between time points. For example, the SG method along the time domain can be used to calculate the derivative value. Furthermore, if there are fluctuations where the light intensity of all wavelengths changes at the same magnification, signal processing is applied to normalize the light intensity of each wavelength by the average value or the sum of the absolute values ​​of the light intensity of all wavelengths.

[0075] The time-series data D2 introduced into the waveform comparator 3452 is compared with the waveform pattern database 3453, which contains previously acquired light intensity data for each wavelength relative to the etching amount. Here, the waveform comparator 3452 compares the waveform pattern database (light intensity data) 3453 with the currently obtained time-series data D2 to find the waveform pattern closest to the current pattern, and then identifies the processing amount of wafer 500 from the closest waveform pattern.

[0076] The identified processing amount D3 is stored in the etching amount storage unit 3454. The light intensity data for each wavelength in the waveform pattern database 3453 is data processed by signal processing performed by the digital signal processing unit 3451, and it is desirable that it is processed by the same signal processing as the time series data D2. However, it is not necessarily required that it be processed by the same signal processing. The etching amount storage unit 3454 transmits the time series data D4 of the processing amount to the processing amount correction unit 3455.

[0077] The processing volume correction unit 3455 corrects the processing volume at each time point based on the time-series progression of the calculated processing volume. For example, if there are fluctuations in the time-series progression of the calculated processing volume caused by noise, the processing volume correction unit 3455 corrects the processing volume at each time point by linearly approximating the time progression of the processing volume. The processing volume correction unit 3455 outputs the corrected processing volume as processing volume data. For example, the processing volume correction unit 3455 outputs the corrected processing volume as processing volume data to the overall control unit 150.

[0078] In the example above, the waveform comparator 3452 and waveform pattern database 3453 were used to determine the processing amount (etching amount) D3 using the time series data D2, but machine learning may also be used. In this case, a learning model or approximation function is generated that takes the time series data D2 as input using the information from the waveform pattern database 3453 and outputs the etching amount D3, and the etching amount D3 is calculated (estimated) using the generated learning model or approximation function.

[0079] Furthermore, in the above example, the waveform comparator 3452 determined the processing amount D3, but it may also calculate error values ​​for two or more waveforms, or intensity values ​​or frequency values ​​for each waveform. For example, when calculating the error value of the entire spectrum, which is the light intensity data for each wavelength, the waveform comparator 3452 calculates the error or absolute value of the light intensity for each wavelength and calculates the sum of them as the error value. Also, for example, when calculating the error value of a specific wavelength in the spectrum, the waveform comparator 3452 calculates the error or absolute value of the light intensity for that specific wavelength and calculates the sum of them as the error value. Also, for example, when calculating the intensity of the spectrum, the waveform comparator 3452 calculates the sum of the intensities of all wavelengths or a specific wavelength in the spectrum as the intensity value. Also, for example, when calculating the frequency value of the spectrum, the waveform comparator 3452 calculates the oscillation frequency of the intensity in the wavelength direction as the frequency value by performing a Fourier transform on the spectrum in the wavelength direction.

[0080] Then, the overall control unit 150 performs endpoint determination in the etching process of the wafer 500 based on the processing amount data output from the processing amount calculation unit 345. The method for determining the endpoint in the etching process of the wafer 500 is not particularly limited, but one example is the following method.

[0081] The overall control unit 150 compares the acquired processing amount data with a predetermined target processing amount and determines whether the current processing amount has reached the target processing amount. If it determines that the current processing amount has reached the target processing amount, it terminates the etching process.

[0082] According to the plasma processing apparatus 100 of Embodiment 1 described above, it is possible to always measure reflected light from the processing target area regardless of the pattern layout of the wafer 500. As a result, highly accurate processing amount measurement (film thickness measurement) and determination of the end point of wafer processing can be achieved. Ultimately, this enables highly accurate processing of devices.

[0083] Furthermore, in the plasma processing apparatus 100 according to Embodiment 1, the processing amount of the wafer 500 is measured based on the detection result of reflected light 312 at the monitor position within the processing area, so that the processing amount can be measured and the end point of wafer processing can be determined with higher accuracy.

[0084] Figure 6A shows the spectrum of reflected light from the electronic circuit portion of the wafer in Embodiment 1, and Figure 6B shows the spectrum of reflected light from the peripheral portion of the wafer in Embodiment 1. As can be seen from Figures 6A and 6B, the spectrum of reflected light 312 differs depending on the acquisition position of the reflected light 312. That is, the spectrum of reflected light 312 in the electronic circuit portion 501, which is the processing target area (Figure 6A), is different from the spectrum of reflected light 312 in the peripheral portion 503, which is outside the processing target area (Figure 6B). Therefore, it is preferable to measure the processing amount of the wafer 500 based on the reflected light at a monitoring position within the electronic circuit portion 501, which is the processing target area.

[0085] In this embodiment, as described above, the amount of wafer 500 processed is measured using reflected light 312 reflected from monitor position P21 or monitor position P24 located within the electronic circuit section 501. As a result, the spectrum observed during the etching process has a shape equivalent to that of Figure 6A. Therefore, it becomes easier to determine the amount of wafer 500 processed based on the spectrum of reflected light 312, enabling highly accurate endpoint determination. Furthermore, by automatically stopping the etching process based on this endpoint determination, processing accuracy can be improved. Specifically, the error from the target processing dimension could be reduced to, for example, 1 nm or less.

[0086] The pattern layout of wafer 500 described above is just one example. Even with other pattern layouts, by controlling the reflection position (monitor position) of the reflected light 312 to be measured on wafer 500, the reflected light at the monitor position closest to the processing position can be measured. Furthermore, it is possible to measure the reflected light within the processing target area. In other words, high-precision processing can be achieved even with wafers having other pattern layouts.

[0087] Furthermore, in this embodiment, so-called spectral matching was used as a method for determining the processing amount (etching amount), but the method for determining the processing amount is not particularly limited. For example, the processing amount may be determined using light intensity data of a specific wavelength in the spectrum or feature data extracted from the spectrum.

[0088] Furthermore, although this embodiment uses only one monitor position, there may be multiple monitor positions. In this case, for example, the average spectrum during processing at multiple monitor positions can be measured. This allows for processing amount measurement, i.e., film thickness and depth measurement (estimation), to be performed using information on the average processing state of the processing distribution within the surface of the wafer 500.

[0089] In this embodiment, the processing amount detection unit 340 of the processing amount measuring instrument 300 is configured to detect the processing amount of the wafer 500 by the etching process. However, for example, the overall control unit 150 may also detect the processing amount of the wafer 500. In other words, although the plasma processing apparatus 100 is equipped with a processing amount detection unit 340 separate from the overall control unit 150, the overall control unit 150 may also perform the function of the processing amount detection unit 340.

[0090] (Embodiment 2) Figure 7 is a schematic diagram showing the positional relationship between the light irradiation unit and the light receiving unit according to Embodiment 2, and is a view of the processing chamber from above. Figure 8 is a diagram showing the wafer processing position and monitoring position in Embodiment 2.

[0091] Embodiment 1 described an example in which the irradiators 323 of the light irradiation unit 321 are arranged in a single row. In contrast, in Embodiment 2, as shown in Figure 7, the multiple irradiators 323A constituting the light irradiation unit 321A are arranged in a two-dimensional plane. In other words, the multiple irradiators 323A constituting the light irradiation unit 321A are arranged in multiple rows on the optical system mounting surface 600. The rest is the same as in Embodiment 1, so the explanation will be omitted. Note that the optical system mounting surface 600 means the plane on which the optical system 320 is installed.

[0092] In this embodiment, the light irradiation unit 321A comprises 36 irradiators 323A. These irradiators 323A are arranged in a two-dimensional plane. Specifically, 12 irradiators 323A are arranged in three rows on the optical system mounting surface 600.

[0093] By arranging multiple irradiators 323A in a two-dimensional plane in this way, the number of monitor positions that the optical system 320 can select can be increased. In other words, by arranging multiple irradiators 323A in a two-dimensional plane, the number of monitor positions that can be illuminated with irradiation light 311 via the optical system 320 can be increased.

[0094] In Embodiment 1, the optical system 320 could select six monitor positions, P21 to P26 (see Figure 4). In contrast, in Embodiment 2, as shown in Figure 8, the optical system 320 could select twelve monitor positions, P21 to P32. Therefore, the optical system condition determination unit 343 can determine a more appropriate monitor position and the corresponding irradiator 323A for the processing positions P11 to P18 of the wafer 500.

[0095] The optical system condition determination unit 343, similar to Embodiment 1, compares the coordinates of the processing positions P11 to P18 on the wafer 500 with the coordinates of the monitor positions P21 to 32 and extracts the combination with the closest distance between the coordinates. For example, in the example in Figure 8, the combinations with the closest distance between the coordinates were the combination of processing position P15 and monitor position P27, and the combination of processing position P17 and monitor position P30.

[0096] The processing amount calculation unit 345 then controls the light irradiation unit 321 of the optical system 320, etc., so that the reflection position of the reflected light 312 is at monitor position P27 or monitor position P30. In other words, the processing amount calculation unit 345 performs film thickness and depth estimation (etching amount estimation) and endpoint determination of the etching process based on the detection result of the reflected light 312 reflected at monitor position P27 or monitor position P30.

[0097] This makes it possible to improve the accuracy of measuring the etching amount and determining the endpoint, similar to Embodiment 1, and ultimately to achieve high-precision processing of the device.

[0098] In the example shown in Figure 8, it is assumed that the monitor positions P21, P24, P27, and P30 are located within the electronic circuit section 501, which is the area to be processed. Therefore, by irradiating with light from multiple irradiators 323A so that the spectra of reflected light 312 from monitor positions P21, P24, P27, and P30 are simultaneously detected by the light receiving unit 325, it becomes possible to achieve more appropriate endpoint determination based on the average processing status of the multiple electronic circuit sections 501.

[0099] (Embodiment 3) Figure 9 is a schematic diagram showing the positional relationship between the light irradiation unit and the light receiving unit according to Embodiment 3, and is a view of the processing chamber from above. Figure 10 is a diagram showing an example of the wafer processing position and monitoring position in Embodiment 3.

[0100] The plasma processing apparatus 100 according to Embodiment 3 includes a plurality of irradiators 323B, each composed of a lens-integrated LED, as the light irradiation unit 321B constituting the optical system 320. The other configurations are the same as in Embodiment 2, so their description is omitted.

[0101] As shown in Figure 9, the light irradiation unit 321B is composed of 48 lens-integrated LEDs, which are arranged on the optical system mounting surface 600. In other words, in Embodiment 3 as well, the multiple irradiators 323B are arranged in a two-dimensional plane.

[0102] In this embodiment, the processing position information acquisition unit 341 acquires information about the processing target area, specifically the coordinates of the four corners P51a to P51d of the roughly rectangular electronic circuit section 501, as shown in Figure 10, and supplies this information to the optical system condition determination unit 343.

[0103] The optical system condition determination unit 343 selects a monitor position from among a plurality of monitor positions in which the distance to the electronic circuit section 501, defined by the coordinates of positions P51a to P51d, is closer than a preset distance, more preferably the monitor position that is closest to the electronic circuit section 501. Even more preferably, the optical system condition determination unit 343 selects a monitor position located within the electronic circuit section 501.

[0104] In the example shown in Figure 10, the electronic circuit section 501, which is the processing area of ​​the wafer 500, is defined as the range specified by positions P51a to P51d. Also, in the example shown in Figure 10, the monitor positions that the optical system 320 can select near the electronic circuit section 501 are monitor positions P31 to P42.

[0105] The optical system condition determination unit 343 compares the range of processing positions defined by positions P51a to P51d with the monitor positions P31 to P42 and determines the monitor positions included within the electronic circuit section 501, which is the area to be processed. In the example shown in Figure 10, three monitor positions P34, P35, and P36 are determined to be included within the electronic circuit section 501.

[0106] By detecting the reflected light 312 reflected at the monitor positions P34, P35, and P36 determined in this way, and performing etching amount measurement (film thickness measurement during etching) and process endpoint determination, the accuracy of etching amount measurement and process endpoint determination can be improved, similar to the embodiment described above. Ultimately, high-precision processing of devices can be achieved.

[0107] (Embodiment 4) Embodiment 4 is an example in which, in the configuration of Embodiment 1, the coordinates of the measurement position of an external inspection device are used as the processing position information of the wafer 500. Other aspects are the same as in Embodiment 1, so their explanation is omitted here.

[0108] The wafer 500, which is the target of processing by the plasma processing apparatus 100, is etched by the wafer processing unit 200, and then its processed shape is measured using an electron microscope.

[0109] Although not shown in the diagram, the plasma processing apparatus 100 is connected to the electron microscope via a cable or the like for communication. The processing position information acquisition unit 341 acquires the measurement position of the processed shape by the electron microscope and supplies the acquired measurement position as processing position information to the optical system condition determination unit 343.

[0110] For example, in the example shown in Figure 4, if the position where the processed shape is measured by the electron microscope corresponds to the processed position P13 on the wafer 500, the processed position information acquisition unit 341 acquires the coordinates of the processed position P13 as processed position information and supplies the acquired processed position information to the optical system condition determination unit 343.

[0111] Even with the plasma processing apparatus according to this embodiment 4, just like in the embodiments described above, it is possible to improve the accuracy of processing volume measurement and processing endpoint determination. Consequently, it is possible to achieve high-precision processing of devices.

[0112] (Embodiment 5) Embodiment 5 is an example in which the optical system condition determination unit 343 determines the irradiator 323 to be used for light irradiation based on the results of a test irradiation by the light irradiation unit 321. Other than that, it is the same as Embodiment 1, so the explanation is omitted here.

[0113] More specifically, in the plasma processing apparatus 100 according to Embodiment 5, prior to etching the wafer 500, a test irradiation is performed on the wafer 500 via each irradiator 323 of the light irradiation unit 321. Then, the optical system condition determination unit 343 determines which irradiator 323 to be used for measuring the processing amount based on the spectrum of the reflected light 312 acquired during this test irradiation. For this reason, in this embodiment, processing position information is not supplied from the processing position information acquisition unit 341 to the optical system condition determination unit 343.

[0114] For example, in the example shown in Figure 4, test irradiation was performed on monitor positions P21 to P26 within the individual pattern 505 of the wafer 500, and the spectra of the reflected light 312 reflected at these monitor positions P21 to P26 were obtained, as shown in Figure 11.

[0115] As shown in Figure 11, the shape of the reflected light spectrum 312 differs at each monitor position P21 to P26. In Embodiment 5, the optical system condition determination unit 343 compares the spectra of the reflected light 312 at each monitor position P21 to P26 with a preset reference spectrum and determines the monitor position that yields the spectrum closest to the reference spectrum. In this embodiment, the reference spectrum is the spectrum of the reflected light at the processing position. Therefore, the monitor position determined in this embodiment can be said to be the monitor position closest to the processing position or processing region of the wafer 500.

[0116] The plasma processing apparatus according to this embodiment 5 also enables high-precision measurement of processing volume and determination of the processing endpoint, similar to the embodiments described above. Ultimately, this makes it possible to achieve high-precision processing of devices.

[0117] In this embodiment, an example was described in which the spectrum of reflected light at the processing position was set as the reference spectrum. However, the reference spectrum does not necessarily have to be the spectrum of reflected light at the processing position, and can be the spectrum of reflected light at any position on the wafer 500.

[0118] As described above, in this embodiment, an example was described in which the processing amount detection unit 343 selects from among a plurality of irradiators 323 the irradiator 323 in which the distance between the reflection position on the wafer 500 where the light irradiated from the irradiator 323 is reflected and the processing position on the wafer 500 is closest.

[0119] However, the processing amount detection unit 343 does not necessarily have to select the irradiator 323 that is closest in distance to the reflection position of the wafer 500 and the processing position of the wafer 500. The processing amount detection unit 343 can determine which irradiator 323 to irradiate based on the difference between the information of each reflection position on the wafer 500 to which the light irradiated from each of the multiple irradiators 323 is reflected, and the information of the processing position of the wafer 500.

[0120] (Embodiment 6) Embodiment 6 is an example in which the monitor position is determined from the signal intensity based on the results of the test irradiation in Embodiment 5. Other aspects are the same as in Embodiment 5 described above, so the explanation is omitted.

[0121] More specifically, in this embodiment, the optical system condition determination unit 343 calculates the error value between the spectrum of reflected light 312 at each monitor position obtained by test irradiation and the reference spectrum, and determines the monitor position based on that error value. The above error value is calculated as the sum of the absolute error values ​​of each wavelength in the spectrum.

[0122] Figure 12 shows an example of the calculation results of the error values ​​between the reflected light spectrum at each monitor position and the reference spectrum in Embodiment 6. In the graph in Figure 12, the horizontal axis represents the coordinates of the monitor position, and the vertical axis represents the error value.

[0123] The spectrum of reflected light 312 can be defined as being closer to the reference spectrum and having a higher signal intensity (lower noise) the smaller its error value. Therefore, in the example shown in Figure 12, the reflected light at monitor position P21, which has the lowest error value, is determined to have the highest signal intensity. This monitor position P21 is then determined to be the monitor position used for film thickness / depth estimation and endpoint determination.

[0124] The plasma processing apparatus according to this embodiment 6 also enables high-precision measurement of processing volume and determination of the processing endpoint, similar to the embodiments described above. Consequently, high-precision processing of devices can be achieved.

[0125] In this embodiment, the signal intensity was calculated based on the error value with respect to a reference spectrum, but the method for calculating the signal intensity is not limited to this. For example, if the reflectivity of the wafer 500 processing location is high and the reflectivity of other parts is low during test irradiation, the signal intensity may be taken as the sum of the intensities of each wavelength in the spectrum of the reflected light obtained from the test irradiation.

[0126] Furthermore, for example, if the spectrum of reflected light reflected at the processing position of wafer 500 has wavelength-direction light intensity vibrations due to the thick transparent film, but no wavelength-direction light intensity vibrations in other parts, the signal intensity may be calculated using the frequency value, which is the frequency of the wavelength-direction light intensity vibrations in the spectrum obtained by test irradiation.

[0127] In this case, signal strength can be defined as the amount of error from the target frequency value. Specifically, the monitoring position where the amount of error is smallest is determined as the monitoring position where the signal strength is highest.

[0128] Although the technology of this disclosure has been described in detail based on embodiments, it goes without saying that the technology of this disclosure is not limited to the embodiments described above and can be modified in various ways without departing from its essence. Furthermore, for example, the embodiments described above are described in detail in order to explain the technology of this disclosure in an easy-to-understand manner and are not necessarily limited to those having all the configurations described. In addition, it is possible to add, delete, or replace some of the configurations of the embodiments described above with other configurations. [Explanation of symbols]

[0129] 100: Plasma processing equipment 150: Overall Control Unit 200: Wafer processing machine 201: Plasma 203: Processing Room 205: Vacuum container 207: Sample stage 209: Window components 211: Shower Plate 211a: Gas inlet 213: Exhaust vent 215: Vacuum pump 217: Displacement control valve 219: Electric field / magnetic field forming section 221: Waveguide 223: Power supply for generating electric fields 225: Magnetic field generating coil 227: Cavity 300: Processing volume measuring instrument 310: Light source section 311: Irradiation light 312:Reflected light 320:Optical system 321: Light irradiation section (multi-point irradiation port) 323: Irradiator (Irradiation Optical Port) 325: Light receiving unit (light receiving port) 330: Detection unit 340: Processing volume detection unit 341: Processing position information acquisition unit 343: Optical System Condition Determination Unit 345: Processing amount calculation unit 3451: Digital signal processing unit 3452:Waveform comparator 3453: Waveform Pattern Database 3454: Etching amount memory unit 3455: Processing volume correction unit 500: Wafer (semiconductor wafer) 501:Electronic circuit section 503: Peripheral area 505: Individual Pattern 600: Optical system installation surface

Claims

1. The processing chamber inside the vacuum container, A plasma processing apparatus comprising a sample stage located in the processing chamber on which a wafer to be processed is placed, A light irradiation unit having multiple irradiators that irradiate light at different positions toward the surface of a wafer placed on the sample stage, A light receiving unit that receives reflected light reflected by the wafer from the light irradiated from the plurality of irradiators, The system includes a processing amount detection unit that detects the amount of wafer being processed based on information obtained from reflected light received by the light receiving unit during the wafer processing, The processing amount detection unit determines which irradiator to use for light irradiation from among the plurality of irradiators based on the difference between information on each reflection position of the wafer to which light irradiated from each of the plurality of irradiators is reflected and information on the processing position of the wafer, and detects the processing amount of the wafer using the determined irradiator. Plasma processing equipment.

2. In the plasma processing apparatus according to claim 1, The processing amount detection unit selects an irradiator from among the plurality of irradiators in which the distance between the reflection position on the wafer where the light irradiated from the irradiator is reflected and the processing position on the wafer is closer than a preset distance, and uses the selected irradiator to detect the processing amount of the wafer. Plasma processing equipment.

3. In the plasma processing apparatus according to claim 2, The processing amount detection unit is, From among the plurality of irradiators, the irradiator that has the closest distance between the reflection position on the wafer where the irradiated light emitted from the irradiator is reflected and the processing position on the wafer is selected, and the amount of processing on the wafer is detected using the selected irradiator. Plasma processing equipment.

4. In the plasma processing apparatus according to claim 2, The processing amount detection unit is, Based on the coordinates of the processing position and the coordinates of the reflection position on the surface of the wafer, the distance between the reflection position and the processing position on the wafer is calculated. Plasma processing equipment.

5. In the plasma processing apparatus according to claim 1, The processing amount detection unit is, Based on the result of comparing the spectrum of the reflected light received by the light receiving unit with a preset reference spectrum, the irradiator used to detect the processing amount of the wafer is selected. Plasma processing equipment.

6. In the plasma processing apparatus according to claim 1, Each of the aforementioned irradiators is composed of a lens and an optical fiber. Plasma processing equipment.

7. In the plasma processing apparatus according to claim 1, Each of the irradiators has an LED light source. Plasma processing equipment.

8. The processing chamber inside the vacuum container, The processing chamber includes a sample stage on which the wafer to be processed is placed, A light irradiation unit having multiple irradiators that irradiate light at different positions toward the surface of a wafer placed on the sample stage, A plasma processing method using a plasma processing apparatus having a light receiving unit that receives reflected light reflected by the wafer from light irradiated from the plurality of irradiators, Based on the difference between the information of each reflection position on the wafer to which light irradiated from each of the plurality of irradiators is reflected and the information of the processing position on the wafer, the irradiator to irradiate the wafer is determined from among the plurality of irradiators, the amount of processing on the wafer is detected using the determined irradiator, and the processing of the wafer is controlled based on the detected amount of processing. Plasma treatment method.

9. In the plasma treatment method according to claim 8, From among the plurality of irradiators, select an irradiator in which the distance between the reflection position on the wafer where the light irradiated from the irradiator is reflected and the processing position on the wafer is closer than a preset distance, and use the selected irradiator to detect the amount of wafer processed. Plasma treatment method.

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