Particle detection method, computer storage medium, and substrate processing apparatus

Abstract

To improve detection accuracy of particles of a processing container.SOLUTION: A particle detection method for detecting particles in a processing container of a substrate processing apparatus includes steps of: charging an atmosphere sampled at a sampling position provided in the processing container, and measuring a current value of the charged atmosphere; Fourier transforming the current value and data of measurement time of the current value, and analyzing a frequency; and determining presence / absence of the particles in the atmosphere on the basis of the result of the frequency analysis, wherein in the step of measuring the current value, the substrate processing apparatus executes a recipe of repeating discharge and discharge stop of a liquid from a discharge part provided in the processing container in a fixed period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a particle detection method, a computer storage medium, and a substrate processing apparatus. [Background technology]

[0002] Patent Document 1 discloses a coating and developing apparatus that forms a resist film on a substrate, transports the substrate to an exposure apparatus, and then performs a development process on the substrate that has been immersion exposed in the exposure apparatus. This coating and developing apparatus includes a processing block provided with processing modules including a pre-exposure processing module that performs liquid processing on the substrate after formation of a coating film including a resist film and before immersion exposure, a post-exposure processing module that performs liquid processing on the substrate after immersion exposure and before development, and a relay block that is provided with a first load / unload module that loads and unloads the substrate to and from the exposure apparatus, and that connects the processing block and the exposure apparatus in the width direction.

[0003] Patent Document 2 discloses a condensation nucleus counter comprising: a saturation section into which a sampling gas is introduced and which creates a condensable vapor atmosphere inside; a condensation section into which the sampling gas that has passed through the saturation section is introduced and which creates a supersaturated vapor atmosphere with a saturation level of 1 or higher and which condenses vapor molecules using particles contained in the sampling gas that has passed through the saturation section as nuclei to condense and grow condensation nuclei with the particles as nuclei; and a particle counting section that is exhausted from the condensation section and counts the number of particles in the sampling gas containing the condensation nuclei. In this condensation nucleus counter, the interiors of the saturation section and the condensation section are each cylindrical spaces, and the sampling gas is introduced into the saturation section along a tangential direction of the cylindrical space, and the sampling gas is rotated in a tornado-like manner from the interior of the saturation section to the interior of the condensation section along the circumferential direction of the cylindrical space while being exhausted from the condensation section along a tangential direction of the cylindrical space. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-057546 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-003879 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology according to the present disclosure improves the accuracy of detecting particles inside a processing vessel. [Means for solving the problem]

[0006] One aspect of the present disclosure is a particle detection method for detecting particles in a processing vessel of a substrate processing apparatus, comprising the steps of: charging an atmosphere sampled at a sampling position provided in the processing vessel; measuring a current value of the charged atmosphere; Fourier transforming data on the current value and the measurement time of the current value to perform frequency analysis; and determining the presence or absence of particles in the atmosphere based on the results of the frequency analysis. In the step of measuring the current value, a recipe is executed in the substrate processing apparatus, which repeats the discharge and cessation of discharge of a liquid from a discharge unit provided in the processing vessel at a regular interval. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to improve the accuracy of detecting particles inside a processing vessel. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a longitudinal sectional view showing an outline of the configuration of a resist coating apparatus according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing an outline of the configuration of a resist coating apparatus according to an embodiment of the present invention. [Figure 3] FIG. 10 is an explanatory diagram for explaining sampling positions in a particle detection test. [Figure 4] 1 is a graph showing current values ​​measured using sampled atmospheres. [Figure 5]10 is a graph showing particle number concentrations estimated using measured current values. [Figure 6] 1 is a graph obtained by Fourier transforming measured current value versus time data. [Figure 7] 10A and 10B are explanatory diagrams for explaining a particle detection method according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the photolithography process in the manufacturing process of semiconductor devices, etc., a series of processes are performed to form a predetermined resist pattern on a semiconductor wafer (hereinafter referred to as "wafer") as a substrate. This series of processes includes, for example, a resist coating process in which a resist solution is supplied onto the wafer to form a resist film, an exposure process in which the resist film is exposed to light, and a development process in which a developer is supplied to the exposed resist film and developed.

[0010] A processing liquid such as a resist liquid or a developer is supplied from a processing liquid supply source to a discharge nozzle and then discharged toward the wafer through the discharge nozzle. Meanwhile, during the period when the processing liquid is not being discharged onto the wafer, a so-called dummy dispense may be performed in which the processing liquid is discharged to a predetermined drainage location. Furthermore, a cleaning liquid such as pure water may be discharged from the discharge nozzle to clean the wafer surface.

[0011] However, when a liquid is discharged from a discharge nozzle as described above, the liquid may scatter as a mist, and the mist-like liquid may float inside the processing vessel as particles. Since particles inside the processing vessel have a negative effect on the formation of a resist pattern, the number and size of particles inside the processing vessel must be strictly controlled in order to form a desired resist pattern. In particular, in recent years, with the miniaturization of semiconductor elements, requirements for particle size have become stricter, and it is therefore desirable to accurately detect the presence or absence of minute particles in the atmosphere inside the processing vessel.

[0012] In wafer processing equipment such as coating and developing equipment, the presence or absence of particles in a processing vessel has traditionally been measured using a measuring instrument. However, in particle measurement, the smaller the number of particles or the smaller the particle size, the more susceptible the measurement is to noise from the measuring instrument, and there is room for improvement in terms of detection accuracy.

[0013] Therefore, the technology according to the present disclosure improves the accuracy of detecting particles inside a processing vessel.

[0014] Hereinafter, a substrate processing apparatus and a particle detection method according to the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0015] <Resist coating equipment> A resist coating apparatus as a substrate processing apparatus according to this embodiment will be described with reference to Figures 1 and 2. Figures 1 and 2 are a longitudinal sectional view and a transverse sectional view, respectively, showing the outline of the configuration of the resist coating apparatus.

[0016] 1, the resist coating apparatus 1 has a processing vessel 10 whose interior can be closed. A loading / unloading port (not shown) for a wafer W serving as a substrate is formed on the side of the processing vessel 10, and an opening / closing shutter (not shown) is provided at the loading / unloading port.

[0017] A spin chuck 20 is provided in the center of the processing vessel 10 as a rotary holder that holds and rotates the wafer W. The spin chuck 20 has a horizontal upper surface, and the upper surface is provided with, for example, a suction port (not shown) that sucks the wafer W. The wafer W can be sucked and held on the spin chuck 20 by suction from the suction port.

[0018] The spin chuck 20 has a chuck drive mechanism 21 equipped with, for example, a motor or the like, and can rotate at a predetermined speed by the chuck drive mechanism 21. The chuck drive mechanism 21 is also provided with an elevation drive source such as a cylinder, and the spin chuck 20 can move up and down.

[0019] A cup 30 is provided around the spin chuck 20 to receive and collect liquid that splashes or drops from the wafer W. A discharge pipe 31 for discharging the collected liquid and an exhaust pipe 32 for exhausting the atmosphere inside the cup 30 are connected to the bottom surface of the cup 30.

[0020] As shown in Fig. 2, a rail 40 extending in the Y direction (left and right direction in Fig. 2) is formed on the side of cup 30 in the positive X direction (upward in Fig. 2). Rail 40 is formed, for example, from the outside of cup 30 on the negative Y direction side (leftward in Fig. 2) to the outside of cup 30 on the positive Y direction side (rightward in Fig. 2). An arm 41 is attached to rail 40.

[0021] A discharge nozzle 42 serving as a discharge unit that discharges a resist liquid as a processing liquid is supported on the arm 41. The arm 41 can be raised and lowered by a nozzle drive unit 43, and the height of the discharge nozzle 42 can be adjusted. The arm 41 is also configured to be movable on the rail 40 by the nozzle drive unit 43. This allows the discharge nozzle 42 to move between a dummy dispense port 44 serving as a standby unit installed outside the cup 30 on the positive Y-direction side, and above the center of the wafer W in the cup 30. The discharge nozzle 42 is also configured to be movable over the surface of the wafer W in the radial direction of the wafer W. The discharge nozzle 42 is connected to a liquid supply device 100 that supplies the resist liquid, as shown in FIG. 1.

[0022] The dummy dispense port 44 is a container for draining the resist liquid discharged from the discharge nozzle 42, that is, for performing a so-called dummy dispense. The dummy dispense is performed periodically at a timing when the resist liquid is not being discharged onto the wafer W, such as when the wafer W is being loaded or unloaded. When performing a dummy dispense, the resist liquid is discharged into the dummy dispense port 44, and the discharged resist liquid is discharged via a drain pipe (not shown).

[0023] 1 and 2, the resist coating apparatus 1 includes a detector 50 as a particle detection unit that detects particles in the atmosphere inside the processing vessel 10. The detector 50 includes a tube 51 as a sampling unit that samples the atmosphere inside the processing vessel 10, and a detector main body 52 as a current measuring unit that measures the current value of the sampled atmosphere.

[0024] One end of tube 51 is connected to detector main body 52, and the other end is disposed on the outer surface of a side wall of dummy dispense port 44 that faces cup 30. When detecting particles in processing vessel 10, the atmosphere in processing vessel 10 is introduced into detector main body 52 from the upper end of tube 51, and the presence or absence of particles in the atmosphere is detected. That is, since particles in the atmosphere sampled at the upper end of tube 51 are detected, the upper end of tube 51 is referred to as sampling position P in this specification.

[0025] The detector body 52 is configured to be able to suck in the atmosphere inside the tube 51. The detector body 52 is also configured to charge the sucked atmosphere, for example, by corona discharge, and measure the current value of the charged atmosphere. The detector body 52 is not particularly limited as long as it is configured to measure the current value of the atmosphere (aerosol) containing particles, and for example, a known detector configuration can be applied. The detector body 52 is not limited to being disposed outside the processing vessel 10, and may be disposed inside the processing vessel 10 as long as normal functioning of the detector body 52 is ensured.

[0026] The resist coating apparatus 1 is controlled by a control unit M. The control unit M is a computer equipped with a processor such as a CPU, a memory, and the like, and has a program storage unit (not shown). The program storage unit stores programs for controlling various processes in the resist coating apparatus 1 and the particle detection process described below. The programs may be recorded on a computer-readable storage medium H and installed from the storage medium H into the control unit M. The storage medium H may be temporary or non-temporary. Some or all of the programs may be realized by dedicated hardware (circuit board).

[0027] Next, a method for detecting particles in the processing vessel 10 in the resist coating apparatus 1 will be described.

[0028] In this embodiment, since the sampling position P is located on the outer surface of the side wall of the pre-dispense port 44, particles generated during pre-dispensing can be easily detected.

[0029] As a specific detection method, first, the atmosphere inside the processing vessel 10 is sampled from the tube 51, and the sampled atmosphere is charged in the detector main body 52, and the current value of the charged atmosphere is measured.

[0030] Next, the measured current value and the data of the measurement time of that current value are Fourier transformed to perform frequency analysis. Then, based on the presence or absence of peaks that appear in the frequency analysis results, the presence or absence of particles in the sampled atmosphere, i.e., the presence or absence of particles at the sampling position P, is determined.

[0031] The particle detection method will be described in more detail below using the results of particle detection tests carried out by the inventors.

[0032] FIG. 3 is an explanatory diagram illustrating the sampling position P in the particle detection test. This test was carried out under three conditions in which the sampling position P was different by changing the installation height of the tube 51 relative to the dummy dispense port 44. The sampling position P in condition A was at the same height as the upper surface of the dummy dispense port 44. The sampling position P in condition B was at a height 2 mm lower than the upper surface of the dummy dispense port 44. The sampling position P in condition C was at a height 4 mm lower than the upper surface of the dummy dispense port 44.

[0033] 4 is a graph showing current values ​​measured using the atmosphere sampled at each sampling position P under conditions A to C. The vertical axis of each graph represents the current value, and the horizontal axis represents the measurement time of the current value. In this test, a testo DiSCmini nanoparticle counter manufactured by Testo SE & Co. KGaA was used as the detector body 52.

[0034] 4 indicates a state in which the resist liquid is not discharged from the discharge nozzle 42 to the dummy dispense port 44, and "discharged" indicates a state in which the resist liquid is discharged from the discharge nozzle 42 to the dummy dispense port 44. In the particle detection test, a recipe was executed in the resist coating apparatus 1 in which the "no discharge" state and the "discharged" state were repeated at regular intervals.

[0035] In this test, one cycle consisted of 10 seconds of no discharge followed by 5 seconds of discharge, and this cycle was repeated 30 times. Figure 4 does not show the measurement results of the current value for 30 cycles, but in the actual test, measurement results of the current value for 30 cycles were obtained.

[0036] The resist liquid discharge time and discharge stop time per cycle are set appropriately depending on the configuration of the detector 50 and the resist coating apparatus 1. In addition, the number of times the operation of discharging and stopping the discharge of the resist liquid is repeated is not particularly limited, and can be changed appropriately depending on the configuration of the detector 50 and the resist coating apparatus 1.

[0037] Figure 5 is a graph showing the particle number concentration estimated using the measured current value. The graph shown in Figure 5 is the result of outputting the particle number concentration from the measured current value using conversion software provided in the detector. The particle number concentration (particles / cm) in the sampled atmosphere is 3 ) correlates with the current value; for example, the greater the number of charged particles, the greater the amount of charge in the atmosphere as a whole, and the greater the measured current value. By utilizing this correlation, it is possible to estimate the particle number concentration from the current value of the sampled atmosphere, as shown in Figure 5.

[0038] However, because minute particles (e.g., less than 100 nm) have a small charge, they are susceptible to noise from the detector (particle counter), and it may be difficult to determine whether the particle's presence has been detected. Specifically, if the measured current value is not zero, it may be difficult to determine whether the particle's presence is reflected in the current value or whether the detector's noise is reflected in the current value. In other words, the method of estimating particle number concentration from the measured current value cannot eliminate the influence of the measuring instrument's noise, which raises concerns about particle detection accuracy.

[0039] On the other hand, in the particle detection method according to this embodiment, frequency analysis is performed by Fourier transforming the data on the measured current value and the measurement time. Fig. 6 is a graph showing the Fourier transform of the data on the current value and the measurement time. Note that this Fourier transform processing may be performed by the control unit M using the measured current value output from the detector main body 52, or a Fourier transform processing function may be implemented in the control unit (not shown) of the detector main body 52, and the Fourier transform processing may be performed by the detector main body 52.

[0040] By performing a Fourier transform on the measured current value data, it is confirmed that there is a peak at a specific frequency, as shown by the arrow in Figure 6. This peak indicates that the current value is high at that specific frequency, and that particles were generated at the timing when the resist coating equipment 1 performed an operation corresponding to that specific frequency.

[0041] 6, no peak appears in the frequency band corresponding to "no discharge" under any of conditions A to C, but a peak appears in the frequency band corresponding to "discharge." That is, it can be seen that under any of the conditions, no particles are generated while the resist liquid is not being discharged from the discharge nozzle 42, but particles are generated while the resist liquid is being discharged.

[0042] Furthermore, in the particle number concentration estimation results shown in Figure 5, there is a period during which the particle number concentration is relatively high in the "no discharge" state of the second cycle under condition A, but according to the frequency analysis results shown in Figure 6, no peak appears in the "no discharge" state of condition A. In other words, according to the frequency analysis results, no particles are detected in the "no discharge" state of condition A. For this reason, the period during which the particle number concentration is relatively high in the second cycle under condition A in Figure 5 is thought to be the result of a false detection of particle generation due to the influence of detector noise, etc.

[0043] As described above, according to the particle detection method of this embodiment, even in cases where the presence or absence of particles is unclear using conventional methods, the presence or absence of particles can be determined based on the results of frequency analysis, thereby improving the accuracy of particle detection.

[0044] 6, the data of the current value during the discharge of the resist liquid and the data of the current value while the discharge of the resist liquid is stopped are each Fourier transformed, but the data may be treated as one piece of data without being divided and then Fourier transformed. However, by performing a Fourier transform on the data of the current value during the discharge of the resist liquid and the data of the current value while the discharge of the resist liquid is stopped, as in FIG. 6, it becomes easier to identify the cause of the generation of particles, that is, in which operation.

[0045] Furthermore, according to the particle detection method described above, the period during which the resist liquid is discharged and stopped is converted into a frequency, and the converted frequency is compared with the peak frequency (the frequency corresponding to the peak) in the frequency analysis, thereby identifying the timing of particle generation. In other words, since the operation of the resist coating apparatus 1 that caused the generation of particles and the timing of particle generation can be identified, it becomes easier to consider more appropriate countermeasures to suppress particles. For example, the results shown in FIG. 6 confirm that particles tend to be generated immediately after the start of pre-dispense. Therefore, countermeasures such as reducing the discharge rate of the resist liquid immediately after the start of pre-dispense and then gradually increasing the discharge rate can be considered.

[0046] Furthermore, the recipe for the resist coating apparatus 1 executed in the process of measuring the current value of the sampled atmosphere may include operations other than discharging and stopping the discharge of resist solution to the dummy dispense port 44. Examples of such operations include discharging and stopping the discharge of an organic solvent (e.g., thinner) onto the wafer W in the pre-wet process, discharging and stopping the discharge of resist solution onto the wafer W in the resist coating process, rotating and stopping the rotation of the spin chuck 20, and raising and lowering the discharge nozzle 42. By performing these operations at different intervals rather than simultaneously, it is possible to identify the operation of the resist coating apparatus 1 corresponding to the peak frequency that appears in the frequency analysis results, making it easier to consider more appropriate countermeasures for suppressing particles. Specific countermeasures that may be considered include, for example, adjusting the discharge speed and discharge height of the solution from the discharge nozzle or the rotation speed of the spin chuck.

[0047] In the above example, the sampling position P is located on the outer surface of the sidewall of the dummy dispense port 44, but the sampling position P is not particularly limited as long as it is located inside the processing vessel 10, and may be located, for example, on the outer surface of the sidewall of the cup 30. When the sampling position P is located on the outer surface of the sidewall, it becomes easier to detect the generation of particles caused by the operation of discharging the liquid toward the wafer W in the cup 30.

[0048] 7, the resist coating apparatus 1 may be provided with a mechanism for moving the tube 51, and the sampling position P may be moved while a recipe is being executed in the resist coating apparatus 1. In the resist coating apparatus 1 configured in this way, if a position where particle generation is predicted is set in advance, the sampling position P can be moved to the preset position in accordance with the operation of the resist coating apparatus 1 executed according to the recipe.

[0049] Specifically, for example, when discharging resist liquid onto the wafer W, the sampling position P can be moved closer to the cup 30, and when performing a dummy dispense, the sampling position P can be moved closer to the dummy dispense port 44. By periodically moving the sampling position P in this manner, the sampling position P at the time when particles were generated can be identified by comparison with the peak frequency in the frequency analysis. Then, the operation of the resist coating apparatus 1 that caused the generation of particles can be identified from the identified sampling position P, making it easier to consider more appropriate countermeasures to suppress particles.

[0050] In the above example, the detector 50 is permanently installed in the resist coating apparatus 1 and detects particle generation during a series of processes on the product wafers W, but the detector 50 may also be temporarily installed in the resist coating apparatus. For example, the detector 50 may be installed to test for particle generation during the development and manufacturing stages of the resist coating apparatus. In this case, if it is found that particles are generated during dummy dispensing, for example, in a particle detection test, the shape of the dummy dispense port 44 and the discharge conditions can be reconsidered. Then, after the resist coating apparatus is completed, the detector 50 is removed.

[0051] Furthermore, for example, when a particle detection test is performed while increasing the exhaust volume of the atmosphere in the processing vessel, particles may be generated when the exhaust volume reaches a certain value. In such a case, by setting the processing conditions with the exhaust volume at which particles are generated as the upper limit, it is possible to suppress particle generation during a series of processes on product wafers W. In other words, by using the particle detection method described above, it is possible to find more appropriate processing conditions for a resist coating apparatus.

[0052] The particle detection method according to this embodiment has been described above. In the above example, a resist coating apparatus has been exemplified as the substrate processing apparatus. However, the substrate processing apparatus may also be, for example, a developing apparatus that supplies a developer to an exposed resist film for development. In the above example, the resist liquid is discharged from the discharge nozzle 42 as a discharge unit. However, the liquid discharged from the discharge unit may be a liquid such as a developer or a cleaning liquid (e.g., pure water) for cleaning the wafer, depending on the desired process to be performed on the wafer W. Regardless of the type of liquid being discharged, when the liquid is discharged from the discharge unit, the liquid may scatter in the form of a mist and float as particles, and therefore the particle detection method described above can be applied.

[0053] Furthermore, the substrate processing apparatus according to the present disclosure can also be applied to processing substrates other than semiconductor wafers, such as FPD (flat panel display) substrates.

[0054] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0055] 1. Resist coating device 10 Processing container 42 Discharge nozzle 50 Detectors 51 tubes 52 Detector body H storage medium M control section W wafer

Claims

1. A particle detection method for detecting particles in a processing vessel of a substrate processing apparatus, comprising: charging the sampled atmosphere at a sampling position provided in the processing vessel and measuring a current value of the charged atmosphere; a step of performing a frequency analysis by Fourier transforming data of the current value and the measurement time of the current value; determining whether or not particles are present in the atmosphere based on the results of the frequency analysis; In the step of measuring the current value, a recipe is executed in the substrate processing apparatus, in which a discharge unit provided in the processing vessel starts and stops discharging a liquid at a fixed cycle.

2. In the step of performing the frequency analysis, Data on the current value and the measurement time of the current value, The data is divided into data during the ejection of the liquid and data during the stop of the ejection of the liquid, 2. The particle detection method of claim 1, further comprising the step of Fourier transforming each of the data.

3. In the step of determining whether or not particles are present, converting a frequency from a cycle of operation of the substrate processing apparatus included in the recipe; The particle detection method according to claim 1 , further comprising the step of comparing the converted frequency with a peak frequency in the frequency analysis.

4. the recipe also includes operations of the substrate processing apparatus other than discharging and stopping the discharging of the liquid; The particle detection method according to claim 3 , wherein the operations in the substrate processing apparatus are performed at different cycles.

5. In the step of measuring the current value, 5. The particle detection method according to claim 1, wherein the sampling position is moved to a predetermined position where generation of the particles is predicted in accordance with an operation of the substrate processing apparatus included in the recipe.

6. A readable computer storage medium storing a program that runs on a computer of a control unit that controls a substrate processing apparatus so as to cause the substrate processing apparatus to execute the particle detection method according to any one of claims 1 to 5.

7. A substrate processing apparatus, a processing vessel in which substrate processing is performed; a discharge unit that discharges a processing liquid onto the substrate; a particle detection unit that detects particles in the processing vessel; a control unit, The particle detection unit a sampling unit that samples the atmosphere inside the processing vessel; a current measuring unit that charges the sampled atmosphere and measures the current value of the charged atmosphere; The control unit charging the sampled atmosphere at the sampling position and measuring the current value of the charged atmosphere; a step of performing a frequency analysis by Fourier transforming data of the current value and the measurement time of the current value; determining whether or not particles are present in the atmosphere based on the results of the frequency analysis; and The substrate processing apparatus is configured to execute a recipe in which the discharge of the liquid from the discharge unit is repeated at regular intervals, starting and stopping the discharge, in the step of measuring the current value.

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