JP7612689B2 - Inspection substrate, its regeneration method, and substrate processing apparatus - Google Patents

Description

The present disclosure relates to an inspection substrate, a method for recycling the same, and a substrate processing apparatus.

In the manufacture of semiconductor devices, a substrate processing system equipped with a transport unit and a processing unit is used to perform various processes, such as chemical processing, film formation processing, and heat treatment, on a substrate (e.g., a semiconductor wafer) to be processed. Patent Document 1 discloses a coating and developing apparatus for coating a substrate with resist and developing the substrate after exposure as a substrate processing system. In this coating and developing apparatus, a substrate for temperature monitoring, called a wireless wafer, is used. The wireless wafer has multiple temperature sensors and a controller, and can transmit the temperature detected by the temperature sensor via wireless communication. When the wireless wafer is placed on the heating plate and when the wireless wafer is transported to the heating plate before and after the placement, the change in the actual temperature of the wireless wafer over time is measured. The control parameters of the heating plate can be appropriately adjusted based on the measurement results.

JP 2006-08489 A

The present disclosure provides a technology that can detect the state of adhesion of contaminants to the surface of an inspection substrate during processing or transportation of the inspection substrate, which is a substrate used for inspection.

One embodiment of the inspection board comprises a plate-shaped base material, an imaging element provided on at least a portion of the surface of the base material, a light-transmitting protective layer formed on the surface of the imaging element, and an output section that outputs the output of the imaging element to the outside of the inspection board, and is capable of detecting the state of adhesion of the contaminants to the protective layer based on the output of the imaging element that changes when light irradiated from a light source is blocked by contaminants adhered to the protective layer.

According to the present disclosure, it is possible to detect the state of adhesion of contaminants to the surface of an inspection substrate while the inspection substrate is being processed or transported.

1 is a schematic cross-sectional view of a substrate processing system according to an embodiment of the substrate processing apparatus. 1 is a schematic vertical cross-sectional view showing a structure of a doctor wafer according to an embodiment. FIG. FIG. 2 is a schematic plan view showing the arrangement of electrodes on a doctor wafer according to one embodiment. 2 is a schematic vertical cross-sectional view showing an example of the configuration of a processing unit included in the substrate processing system. FIG. 11 is a schematic vertical sectional view showing another example of the configuration of a processing unit included in the substrate processing system. FIG. 1 is a schematic vertical cross-sectional view showing an example of a configuration of a substrate transport device included in a substrate processing system. 11 is a graph showing an example of the change over time in particle level from the start of treatment liquid from a nozzle. 3 is a piping diagram showing an example of the configuration of a processing liquid supply system that supplies a processing liquid to a nozzle. FIG. 13 is a flowchart illustrating a specific example 4 of the operation of the doctor wafer. FIG. 13 is a diagram showing an example of particle distribution related to the fifth specific example. FIG. 13 is a diagram showing another example of particle distribution related to the fifth embodiment. FIG. 13 is a diagram showing yet another example of particle distribution related to the fifth embodiment. FIG. 13 is a diagram showing an example of particle distribution related to Example 6. 1A to 1C are schematic cross-sectional views for explaining detection of particle sizes using a doctor wafer. FIG. 11 is a distribution diagram for explaining detection of particle sizes using a doctor wafer. 10A to 10C are schematic cross-sectional views illustrating a case where a scratch is formed on a doctor wafer. FIG. 11 is a schematic cross-sectional view showing another configuration example of the doctor wafer. FIG. 11 is a schematic cross-sectional view showing another configuration example of the doctor wafer. FIG. 11 is a schematic cross-sectional view showing another configuration example of the doctor wafer. FIG. 11 is a schematic cross-sectional view showing another configuration example of the doctor wafer. FIG. 13 is a schematic plan view showing another configuration example of the doctor wafer.

One embodiment of a substrate processing apparatus is described with reference to the attached drawings.

Figure 1 is a diagram showing the schematic configuration of a substrate processing system according to this embodiment. In the following, in order to clarify the positional relationships, mutually orthogonal X-axis, Y-axis, and Z-axis are defined, and the positive direction of the Z-axis is the vertical upward direction.

As shown in Figure 1, the substrate processing system 1 includes a loading/unloading station 2 and a processing station 3. The loading/unloading station 2 and the processing station 3 are provided adjacent to each other.

The loading/unloading station 2 includes a carrier placement section 11 and a transport section 12. A plurality of carriers C are placed on the carrier placement section 11, each of which holds a plurality of substrates, in this embodiment semiconductor wafers (hereinafter referred to as wafers W), in a horizontal position.

The transport section 12 is provided adjacent to the carrier placement section 11, and includes a substrate transport device 13 (transport mechanism) and a transfer section 14. The substrate transport device 13 includes a wafer holding mechanism that holds a wafer W (substrate). The substrate transport device 13 is capable of moving horizontally and vertically and rotating about a vertical axis, and transports the wafer W between the carrier C and the transfer section 14 using the wafer holding mechanism.

The processing station 3 is provided adjacent to the transport section 12. The processing station 3 includes a transport section 15 and a plurality of processing units 16. The plurality of processing units 16 are arranged side by side on both sides of the transport section 15.

The transfer section 15 has a substrate transfer device 17 (transfer mechanism) therein. The substrate transfer device 17 has a wafer holding mechanism that holds the wafer W. The substrate transfer device 17 is also capable of moving in the horizontal and vertical directions and rotating about a vertical axis, and transfers the wafer W between the delivery section 14 and the processing unit 16 using the wafer holding mechanism.

The processing unit 16 performs a predetermined substrate processing on the wafer W transported by the substrate transport device 17.

The substrate processing system 1 is equipped with a notch aligner 90, i.e., a positioning device, that aligns the wafer in the circumferential direction. The notch aligner 90 can be provided, for example, in the transport section 12 of the loading/unloading station 2 (for example, in the transport space of the substrate transport device 13 or in the delivery section 14). Instead of the notch aligner 90, a device that positions the wafer by detecting the orientation flat may be used as the positioning device.

The substrate processing system 1 may include a doctor wafer storage section 92 for storing doctor wafers (test substrates) DW, which will be described later. The doctor wafer storage section 92 may be provided at any position within the substrate processing system 1, provided that the substrate transport device 13 or the substrate transport device 17 can access the doctor wafer storage section 92.

The substrate processing system 1 also includes a control device 4. The control device 4 is, for example, a computer, and includes a control unit 18 and a memory unit 19. The memory unit 19 stores programs that control various processes executed in the substrate processing system 1. The control unit 18 controls the operation of the substrate processing system 1 by reading and executing the programs stored in the memory unit 19.

Such a program may be recorded on a computer-readable storage medium and installed from the storage medium into the memory unit 19 of the control device 4. Examples of computer-readable storage media include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical disk (MO), and a memory card.

In the substrate processing system 1 configured as described above, first, the substrate transfer device 13 in the loading/unloading station 2 removes the wafer W from the carrier C placed on the carrier placement section 11, and places the removed wafer W on the transfer section 14. The wafer W placed on the transfer section 14 is then removed from the transfer section 14 by the substrate transfer device 17 in the processing station 3, and transferred to the processing unit 16.

The wafer W transferred to the processing unit 16 is processed by the processing unit 16, and then transferred out of the processing unit 16 by the substrate transfer device 17 and placed in the transfer section 14. The processed wafer W placed in the transfer section 14 is then returned to the carrier C in the carrier placement section 11 by the substrate transfer device 13.

Contaminants, particularly particles, adhere to the wafer W at various locations within the above-mentioned substrate processing system 1. In order to analyze the cause of particle adhesion to the wafer W, the following doctor wafer DW (test substrate) is transported and processed within the substrate processing system 1.

As will be clear from the following explanation, the doctor wafer DW is capable of detecting a wide range of contaminants other than particles, such as water marks or surface defects such as scratches. In the following, this specification will use particles as an example to explain the most typical detection target.

The configuration of the doctor wafer DW is explained below. Figure 2 shows one configuration example of the doctor wafer DW. The doctor wafer DW comprises a wiring layer 102, a light receiving layer 104, and a protective layer 106, which are sequentially stacked on a substrate 100 (disk-shaped base material) made of a semiconductor wafer.

The wiring layer 102 and the light receiving layer 104 can be formed using a known imaging element (e.g., a back-illuminated CMOS) formation technique. The doctor wafer DW can also be said to be an imaging element of the same size as the wafer W. The wiring layer 102 and the light receiving layer 104 may be configured to correspond to a CCD imaging element.

The light receiving layer 104 has a large number (multiple) of photodiodes arranged in a matrix. Since there is no need to distinguish colors in the doctor wafer DW, no color filters are provided on the photodiodes. Therefore, the light receiving layer 104 of the doctor wafer DW has a detection resolution that corresponds exactly to the number of photodiodes (number of pixels). Each photodiode is hereinafter referred to as a pixel 105. In a non-limiting exemplary embodiment, the size of one pixel 105 is 5 nm.

The protective layer 106 is preferably formed from a material that has sufficient optical transparency, is not easily damaged by the processing fluid to which the doctor wafer DW is exposed, and has surface properties (e.g., hydrophobicity) similar to those of the wafer W (the product wafer). In the illustrated embodiment, the protective layer 106 is formed from a pixel protection damper 106a provided on the light receiving layer 104 and transparent glass (SiOx) 106b. The surface properties (e.g., hydrophobicity) of the transparent glass are similar to those of the wafer W.

The material constituting the protective layer 106 (particularly its surface) can be changed depending on the processing fluid to which the doctor wafer DW is exposed. In order to bring the surface characteristics (e.g., hydrophobicity) of the protective layer 106 closer to the surface characteristics of the substrate to be processed, a light-transmitting coating having the desired characteristics (e.g., a thin film of transparent PFA or PTFA) may be applied. In order to make the protective layer 106 resistant to various processing liquids, a light-transmitting coating may be provided on the outermost surface of the protective layer 106. As the light-transmitting coating, SiN, SiOx, etc. can be used when acid resistance is desired, SiOx, etc. when alkali resistance is desired, and SiOx, etc. can be used when oil resistance is desired.

As shown in Figure 3, a plurality of electrodes 108 (power receiving sections) are provided on the periphery of the doctor wafer DW. The electrodes 108 function as power receiving electrodes for receiving power to operate the image pickup elements (102+104), as input electrodes for receiving command signals from an external device (e.g., a signal processing device) that instruct the image pickup elements to read pixel data, and as output electrodes for outputting pixel data output from the doctor wafer DW to an external device (e.g., a signal processing device).

Two or more different functions among the above functions may be assigned to the same electrode 108 (electrode member). Each electrode 108 (electrode member) may be assigned one different function. As for the power to operate the image sensor, when the image sensor is a back-illuminated CMOS, an example is a supply electrode to the pixel amplifier.

The electrode 108 is provided at a position where it can make electrical contact with various components that come into contact with the wafer W in the substrate processing system 1, such as the gripping claws of a mechanical spin chuck (described later) and the holding claws of a transport arm (described later). The electrode 108 can be provided so as to be exposed, for example, on the apex surface (peripheral side surface) of the doctor wafer DW, the bevel portion, or a flat portion nearby.

The electrodes 108 are electrically connected to the wiring layer 102. The gripping claws of the mechanical spin chuck are positioned so as to contact the black electrodes 108 in FIG. 3. The holding claws of the transport arm are not necessarily positioned so as to contact the black electrodes 108, but are positioned so as to contact, for example, the white electrodes 108. In this case, a connection line 110 can be provided to connect the electrodes 108 that have the same role (for example, electrodes that transmit and receive power, command signals, and pixel data (image signals) between a specific area of the doctor wafer DW).

When a particle adheres to the surface of the protective layer 106 of the doctor wafer DW, the illumination light irradiated onto the doctor wafer DW is blocked by the particle. In other words, the output of the pixel 105 below the particle becomes smaller. This can be used to detect the distribution of particles on the doctor wafer DW.

In addition, by reading out images (pixel data) from the doctor wafer DW at a sufficiently high frame rate (e.g., several hundred to several thousand fps), it is also possible to grasp the movement of particles over time, for example, during liquid processing. In this case, since the amount of data becomes enormous, data may be obtained for a short time interval (corresponding to the above-mentioned high frame rate) only from pixels located on two mutually perpendicular lines (a line extending in the X direction and a line extending in the Y direction) that extend along the diameter of the doctor wafer DW. The movement of particles over time may be grasped by forming a signal-time 3D map based on this data.

In order to detect particles on the doctor wafer DW, it is necessary to irradiate the doctor wafer DW with light. For this reason, lighting devices can be provided in various locations within the substrate processing system 1. The location of the lighting device can be arbitrary, but it is preferable to provide it in a location where particles are particularly likely to be generated. Examples of locations where particles are likely to be generated include within the processing unit 16 and near the transfer section 14 where the wafer W is transferred.

Next, the configuration of the processing unit 16 equipped with the illumination device will be described. As shown in FIG. 4, the processing unit 16 includes a chamber 20, a spin chuck (substrate holding mechanism) 30, a processing fluid supply unit 40, and a collection cup 50.

The chamber 20 houses a spin chuck 30, a processing fluid supply unit 40, and a collection cup 50. A Fan Filter Unit (FFU) 21 is provided on the ceiling of the chamber 20. The FFU 21 creates a downflow within the chamber 20.

The spin chuck 30 is configured as a mechanical chuck. The spin chuck 30 has a substrate holding portion 31. The substrate holding portion 31 has a disk-shaped support plate 32 and a plurality of gripping claws 33 provided on the periphery of the support plate 32, preferably at equal intervals in the circumferential direction. At least one of the gripping claws 33 is movable. The spin chuck 30 holds the wafer W in a horizontal position by engaging the gripping claws 33 with the periphery of the wafer W. The support plate 32 is rotated by an electric motor (drive unit) 34, which rotates the wafer W around a vertical axis.

The gripping jaws 33 are provided with electrodes 35 that can be in electrical contact with the electrodes 108 of the doctor wafer DW. The notch N (see FIG. 3) of the doctor wafer DW is in a predetermined positional relationship with the electrodes 108 of the doctor wafer DW. Since the doctor wafer DW is positioned in the circumferential direction by the notch aligner 90, each electrode 108 of the doctor wafer DW always comes into contact with a predetermined electrode 35 of the gripping jaws 33 when held by the spin chuck 30.

Connected to the electrode 35 are a power supply 36 that supplies the power required to operate the doctor wafer DW (e.g., power to operate a pixel amplifier), and a signal processing device (transmitter/receiver and calculation unit) 37 that outputs a command signal instructing the doctor wafer DW to read pixel data and processes the pixel data signal output from the doctor wafer DW.

The processing fluid supply unit 40 has one or more nozzles 41 that discharge processing fluid. The nozzle 41 is supported at the tip of a nozzle arm 42 that can rotate around a vertical axis, and can move at least between a position directly above the center of the wafer W and a position directly above the peripheral edge of the wafer W. A processing fluid supply mechanism 43 that supplies processing fluid (processing liquid, processing gas) to the nozzle 41 is connected to each nozzle 41. Multiple types of processing fluid may be supplied from each nozzle 41, in which case multiple processing fluid supply mechanisms 43 are connected to one nozzle 41. The number of nozzles 41 and the number of nozzle arms 42 provided in one processing unit 16 are arbitrary.

The substrate holding portion 31 of the spin chuck 30 is surrounded by a collection cup 50. The collection cup 50 collects the processing liquid scattered from the wafer W. A drainage port 51 and an exhaust port 52 are formed at the bottom of the collection cup 50. The processing liquid is discharged from the drainage port 51 to the outside of the collection cup 50. The exhaust port 52 is constantly sucked during normal operation of the processing unit 16, so that the atmosphere in the space above the wafer W (e.g., clean air supplied from the FFU 21 to the chamber 20) is sucked into the collection cup 50. The airflow generated by this prevents the processing liquid scattered from the wafer W from reattaching to the wafer W.

An illumination device 45 is provided on the underside of the nozzle arm 42. The illumination device 45 is arranged on the nozzle arm 42 so that when the nozzle 41 is positioned directly above the center of the wafer W, the illumination device 45 can continuously (without interruption) illuminate the area from the center to the periphery of the surface of the wafer W. When the illumination device 45 is turned on when the nozzle 41 is positioned directly above the center of the doctor wafer DW, a linear or elongated strip-shaped illumination area is formed on the surface of the doctor wafer DW, which extends continuously in the radial direction from the center to the periphery.

FIG. 5 shows a modified example of the processing unit 16. In this modified example, an illumination device 46 is provided in the place where the FFU 21 was provided in the example of FIG. 4. The illumination device 46 can be configured from a disk-shaped member having a diameter at least larger than the diameter of the wafer W. The illumination device 46 can be configured to include a light emitting unit 46a and a polarizing filter 46b made of graphene or the like. In this case, the surface of the wafer W can be irradiated with parallel light (light that travels substantially only in a direction perpendicular to the surface of the wafer W), and the particle inspection accuracy can be improved even if the wafer W is irradiated with light from a relatively distant position. The configuration of the illumination device 45 shown in FIG. 4 may be the same as that of the illumination device 46. In the modified example of FIG. 5, an outlet of the side flow type FFU 21 can be provided on the side wall of the chamber 20. Other than the above-mentioned points, the configuration of the processing unit 16 in FIG. 5 may be the same as that of the processing unit in FIG. 4.

Next, the configuration of the substrate transport device 17 (particularly the configuration near the substrate holder) will be described with reference to Figure 6. The substrate transport device 17 has a movable base 171 that can translate in the X direction (horizontal direction) and the Z direction (vertical direction) and can rotate around a vertical axis. A fork 172 (substrate holder) that can move back and forth horizontally is provided on the movable base 171.

6 shows the fork 172 in the retracted position. The fork 172 is in the forward position when transferring the wafer W between a wafer holding structure such as the spin chuck 30 of the processing unit 16 or the stage of the transfer section 14, and is in the retracted position when transferring the wafer W between the wafer holding structures.

The fork 172 is provided with a number of holding claws 173, at least one of which is movable. By moving the movable holding claw 173, the fork 172 can hold and release the wafer W (doctor wafer DW). The holding claw 173 is provided with an electrode 175 that can be electrically contacted with the electrode 108 of the doctor wafer DW. When the doctor wafer DW is properly positioned, each electrode 108 always comes into contact with the electrode 175 of a predetermined holding claw 173 when held by the fork 172.

The electrode 175 is connected to a power supply 177 that supplies the power necessary to operate the doctor wafer DW, and a signal processing device 179 (or the aforementioned signal processing device 37) that outputs a command signal instructing the doctor wafer DW to read pixel data and processes the pixel data (image signal) output from the doctor wafer DW.

The movable base 171 is provided with an illumination device 174. The illumination device 174 is provided so as to irradiate the entire surface of the doctor wafer DW held by the fork 172 in the retracted position. The configuration of the illumination device 174 may be similar to that of the illumination devices 45 and 46 provided in the processing unit 16.

The lighting device 174 may be a strip-shaped device (preferably with a length equal to or greater than the diameter of the doctor wafer DW) extending in a direction perpendicular to the direction in which the forks 172 move forward and backward. In this case, it is sufficient that the entire area of the doctor wafer DW crosses the strip-shaped irradiation area of the lighting device 174 as the forks 172 move forward and backward.

As shown in FIG. 5, a wafer loading/unloading port 22 with a shutter is provided on one of the side walls of the chamber 20 of the processing unit 16 (the same applies to the configuration in FIG. 4, but is not shown in FIG. 4). A rectangular lighting device 47 having a length equal to or greater than the diameter of the wafer W may be provided on the ceiling of the wafer loading/unloading port 22. In this case, when the fork 172 holding the doctor wafer DW passes under the lighting device 47, the doctor wafer DW can be inspected.

Units/apparatus other than the processing unit 16 shown in Figures 4 and 5 and the substrate transport device 17 shown in Figure 6 can also be provided with electrodes that can be in electrical contact with the electrode 108 of the doctor wafer DW, as well as an illumination device that irradiates light onto the doctor wafer DW in such units/apparatus. In this case, too, the electrodes can be connected to a power source that supplies the power required to operate the doctor wafer DW, and a signal processing device that outputs a command signal to instruct the doctor wafer DW to read pixel data and processes the pixel data (image signal) output from the doctor wafer DW.

The lighting device can also be installed on the ceiling of the room that forms the wafer transport space, the ceiling of the delivery section 14, etc.

Next, specific examples of investigating particle generation status and/or analyzing the cause of generation using the doctor wafer DW will be described. In each of the following specific examples, the amount of particles present on the surface of the doctor wafer DW is measured based on the signal output from each pixel 105 of the doctor wafer DW.

<Specific Example 1>
A carrier C containing a doctor wafer DW is placed on the carrier placement section 11 (Step 1). The forks (substrate holders) of the substrate transport device 13 in the loading/unloading station 2 enter the carrier C and remove the doctor wafer DW from the carrier C (Step 2). The forks of the substrate transport device 13 enter the delivery section 14 and place the doctor wafer DW on the delivery section 14 (Step 3).

If the notch aligner 90 is in the transport section 12, the doctor wafer DW is positioned between step 2 and step 3. By performing positioning, the electrode 175 of the fork 172 of the substrate transport device 17 (13) and the electrode 35 of the spin chuck 30 can be reliably contacted with the electrode 108 of the doctor wafer DW. If the positioned doctor wafer DW is stored in the carrier C, the positioning operation can be omitted. If the doctor wafer storage section 92 is in the transport section 12, the series of steps may start with a step of transporting the positioned doctor wafer DW stored in the doctor wafer storage section 92 from the doctor wafer storage section 92 to the delivery section 14.

After step 3, the forks of the substrate transport device 17 of the processing station 3 enter the transfer section 14 and remove the doctor wafer DW from the transfer section 14 (step 4). The forks of the substrate transport device 17 enter the processing unit 16 and transfer the doctor wafer DW to the spin chuck 30 in the processing unit 16 (step 5). Liquid processing is performed on the doctor wafer DW in the processing unit 16 (step 6). After the liquid processing is completed, the forks of the substrate transport device 17 enter the processing unit 16 and remove the doctor wafer DW from the processing unit 16 (step 7). The forks of the substrate transport device 17 enter the transfer section 14 and place the doctor wafer DW on the transfer section 14 (step 8). The forks of the substrate transport device 13 enter the transfer section 14 and remove the doctor wafer DW from the transfer section 14 (step 9). The forks of the substrate transport device 13 enter the original carrier C and store the doctor wafer DW in the carrier C (step 10).

During steps 1 to 10, the change in the adhesion state of particles on the doctor wafer DW can be grasped based on the output signal of the doctor wafer DW. The doctor wafer DW can output a signal to the outside while the electrode 108 of the doctor wafer DW is in contact with an external electrode (for example, the electrode 35 of the gripping claws 33 of the spin chuck 30 of the processing unit 16, or the electrode 175 of the holding claws 173 of the fork 172 of the substrate transport device 17). If data when the electrode 108 of the doctor wafer DW is not in contact with the above-mentioned external electrode is also required, a data buffer (memory unit) may be provided on the doctor wafer DW as described later, or a wireless output unit (antenna) may be provided on the doctor wafer DW (described later).

By investigating the change in the amount of particles (here, for example, the total amount of particles) on the doctor wafer DW from step 1 to step 10, it is possible to identify the steps where a large number of particles are generated. By focusing on taking measures against particles in these identified steps, it is possible to efficiently reduce particles.

When the wafer W is being processed without any problems, the doctor wafer DW may be used to periodically obtain data on the transition of the particle amount as described above. By comparing the data on the transition of the particle amount obtained at a certain time with the data on the transition of the particle amount obtained earlier, it is possible to predict the possibility of a problem related to particles occurring. For example, if the particle amount increases compared to before in steps 3, 4, 8, 9, etc., in which the doctor wafer DW is inserted and removed from the transfer section 14, it is presumed that particle-causing substances are attached to the transfer section 14. In this case, particle contamination of the wafer W can be prevented by cleaning the transfer section 14.

A series of steps excluding only step 6 (liquid processing) from step 1 to step 10 above may be performed (steps 5 and 7 related to loading and unloading into and from processing unit 16 may be performed) to detect particles generated during transport. By identifying the coordinates of the location where particles have increased during transport, it can be assumed that a component of the substrate processing system in the vicinity of the coordinates is causing the particles, and measures against the particles can be easily taken.

Steps 1 to 10 may be performed while changing only the processing unit 16 that is the target of steps 5 to 7. In this case, it is possible to identify the processing unit 16 that is likely to generate particles.

<Specific example 2>
The above-mentioned step 6 can be further divided to investigate the transition of the particle amount. After the above-mentioned step 5 is completed (i.e., when the doctor wafer DW is held on the spin chuck 30), the doctor wafer DW is subjected to liquid processing in the processing unit 16 (step 6). Step 6 is composed of a plurality of steps (sub-steps). First, the spin chuck 30 is rotated to rotate the doctor wafer DW, and a pre-wet liquid (e.g., DIW) is supplied to the doctor wafer DW from the nozzle 41 (step 61). Next, the chemical liquid A is supplied to the doctor wafer DW (step 62), then a rinsing liquid is supplied to the doctor wafer DW (step 63), then a chemical liquid B is supplied to the doctor wafer DW (step 64), then a rinsing liquid is supplied to the doctor wafer DW (step 65), then IPA is supplied to the doctor wafer DW (step 66), and then the doctor wafer DW is shaken off and dried (step 67).

By investigating the change in the amount of particles (here, for example, the total amount of particles) on the doctor wafer DW between steps 61 and 67, it is possible to identify the steps where a large number of particles are generated. By focusing on particle countermeasures at these identified steps, it is possible to efficiently reduce particles. For example, if the amount of particles is not sufficiently low after step 65, it is presumed that there is some problem with the rinsing process. In this case, it is sufficient to check whether there is a problem with the conditions for the rinsing process and whether there is any contamination, etc., of the components of the processing unit 16 related to the rinsing process.

In this specific example 2, as in specific example 1, while the wafer W is being processed without any problems, the doctor wafer DW may be used to periodically acquire data on the transition of the particle amount as described above. By comparing the data on the transition of the particle amount acquired at a certain time with the data on the transition of the particle amount acquired earlier, it is possible to predict the possibility of a problem related to particles occurring.

<Specific example 3>
The contamination status of a certain nozzle 41 and the processing fluid supply mechanism 43 connected thereto can be detected by using the doctor wafer DW. In this case, the nozzle 41 supplies the processing liquid to the vicinity of the center of the doctor wafer DW rotated by the spin chuck, and the particle level detection by the doctor wafer DW is performed only near the center of the doctor wafer DW. As shown in the graph of Figure 7, the change over time in the particle amount detection value by the doctor wafer DW (specifically, the increase in the particle amount from before the start of processing) is detected from the time when the nozzle 41 starts to eject the processing liquid.

The configuration of one nozzle 41 and the treatment fluid supply mechanism 43 connected thereto is shown diagrammatically in Figure 8. From a main supply pipe 431 for the treatment liquid (e.g., a circulation pipe connected to a treatment liquid storage tank), branch supply pipes 432 branch off toward each treatment unit 16. In the branch supply pipe 432, a flow meter 433, a constant pressure valve 434 functioning as a flow control valve, and an opening/closing valve 435 are interposed in order from the upstream side. The nozzle 41 is connected to the downstream end of the branch supply pipe 432.

In such a piping system, if the amount of particles is high immediately after the nozzle 41 starts to eject the processing liquid, and then decreases, as shown by the solid line in the graph of Figure 7, it is highly likely that the area near the nozzle outlet of the nozzle 41 is contaminated. In such a case, a possible solution would be to change the process recipe so that a dummy dispense of about 3 seconds is performed before the nozzle 41 starts to eject the processing liquid.

7, suppose that the amount of particles is low immediately after the nozzle 41 starts to discharge the processing liquid, but increases at a point T (sec) (about 5 sec in the graph) after the start of discharge, and then decreases. In this case, it is understood that there is a high possibility that a piping system component located a distance D (cm) upstream from the tip of the nozzle 41 is contaminated. If the discharge flow rate of the processing liquid from the nozzle 41 is V (ml/sec) and the cross-sectional area of the piping is A ( ^cm2 ), L can be approximately calculated by the following formula.
D = VT/A

For example, if the component located at a distance D from the tip of the nozzle 41 is the on-off valve 435, it is highly likely that the on-off valve 435 is contaminated or that dust is being generated by the opening and closing action of the on-off valve 435. In this case, the on-off valve 435 can be cleaned or replaced with a new one. If the on-off valve 435 is contaminated, it may be possible to remove contaminants from the branch supply pipe 432 (including the liquid contact surface of the on-off valve 435) by performing a dummy dispense from the nozzle 41, preferably at a relatively large flow rate and for a relatively long period of time.

If the distance D is greater than the distance from the tip of the nozzle 41 to the upstream end of the branch supply pipe 432, there is a high possibility that the processing liquid flowing through the main supply pipe 431 is contaminated. In this case, processing in all processing units 16 may be temporarily stopped to check the degree of contamination of the processing liquid flowing through the main supply pipe 431.

<Specific example 4>
Next, a determination as to whether or not a wafer W can be processed in the processing unit 16 and a corresponding action, which is performed, for example, periodically using the doctor wafer DW, will be described with reference to the flowchart of FIG.

First, it is determined whether the surface of the doctor wafer DW (referred to as "DrW" in the flow chart of FIG. 9) is sufficiently clean to perform the inspection (step 201). This determination can be made, for example, by holding the doctor wafer DW on the substrate transfer device 17 or the spin chuck 30 of the processing unit 16 and reading image data from the doctor wafer DW. The determination can be made, for example, by determining whether the particles present on the surface of the doctor wafer DW are below a total particle quantity reference value determined for each particle size.

If the result of the judgment is negative (NG), that is, if it is determined that the surface of the doctor wafer DW is contaminated, the inspection is temporarily stopped (step 202). In this case, the surface of the contaminated doctor wafer DW can be subjected to two-fluid cleaning or scrub cleaning, or a regeneration process of the surface of the doctor wafer DW can be performed (described in detail later). The contaminated doctor wafer DW can be replaced with another clean doctor wafer DW, and the process can proceed to step 203.

If the result of the judgment is YES (OK), that is, if it is judged that the surface of the doctor wafer DW is sufficiently clean, a series of processes are performed on the doctor wafer DW using the process recipe of the wafer W. After the processes are completed, the amount of particles on the surface of the doctor wafer DW is measured (step 203). This measurement can be performed, for example, while the doctor wafer DW continues to be held by the spin chuck 30 of the processing unit 16.

Then, the amount of particles before and after the liquid processing is compared (step 204), and if the increase in the amount of particles is equal to or less than a predetermined threshold, the judgment result is OK, and processing of the wafer W by the processing unit 16 is permitted (step 205). This completes the inspection.

If the increase in the amount of particles exceeds a predetermined threshold, the judgment result is NG. The flow then proceeds to step 206, and if it is a second NG judgment, processing of the wafer W by that processing unit 16 is prohibited (step 207) (details will be described later).

If it is determined in step 206 that the result is a first NG judgment, an alarm is generated by a user interface such as a display or an alarm generator, and processing of the wafer W by the processing unit 16 being inspected is temporarily prohibited (step 208). If inspection using the doctor wafer DW is being performed in parallel with normal processing of the wafer W, the processing schedule may be changed to exclude that processing unit 16.

Next, the time-dependent change data of particles measured using the doctor wafer DW is compared with the processing log of the processing unit 16 to estimate the cause of particle generation. The processing log is data showing the relationship between time and the procedure executed, and is a collection of data in a format such as "13:56:25: Opening of the on-off valve of the processing fluid supply mechanism 43 (start of ejection of chemical solution A from the nozzle 41)." Specifically, the cause of particle generation is estimated by making a judgment such as that described in the above-mentioned specific examples 2 and 3 (step 209).

Next, it is determined whether the cause of the particle generation is (A) contamination of the processing fluid supply mechanism 43 (liquid supply system) or (B) something else (step 210). For an example of contamination of the liquid supply system (A), please refer to the above-mentioned specific examples 2 and 3.

If the cause of particle generation is (A) dirt in the piping (including valves, flow meters, etc.) of the processing fluid supply mechanism 43 (liquid supply system), for example, cleaning (flushing) of the liquid supply system is performed. Specifically, for example, a dummy spence is performed from the nozzle 41 using the processing fluid supply mechanism 43 for a predetermined time to wash away dirt in the piping (step 211).

(B) Examples of other causes include dirt on the inner walls of the chamber 20 or dirt on the collection cup 50. In the case of dirt on the chamber 20 or the collection cup 50, particles tend to concentrate on the peripheral portion of the doctor wafer DW, and based on this, it can be determined that the cause is (B).

An example of determining the cause of occurrence (A) or (B) will be described below. If a large number of particles are detected at the location where the processing liquid discharged from the nozzle 41 landed on the doctor wafer DW (for example, the center of the doctor wafer DW) during processing, it can be determined that there is a high possibility that the cause of particle generation is within the processing fluid supply mechanism 43 (within the flow path of the processing liquid) (i.e., the cause is (A)). On the other hand, if the recovery cup 50 is highly contaminated, the processing liquid scattered from the doctor wafer DW collides with the recovery cup 50, scatters together with the contaminants, and reattaches to the peripheral portion of the doctor wafer DW. Therefore, if a large number of particles are detected on the peripheral portion of the doctor wafer DW during processing, it can be determined that there is a high possibility that the cause is (B). Note that if a large number of particles are detected on the peripheral portion of the doctor wafer DW while processing is being performed with the processing liquid landed on the center of the doctor wafer DW, it can be seen that there is a higher possibility that the cause is (B).

If it is determined that the amount of particles has increased due to dirt falling off the chamber 20 or collection cup 50, cleaning liquid is sprayed from a cup inner wall cleaning nozzle or chamber inner wall cleaning nozzle (not shown) to clean the inner walls of the cup and the chamber (step 212).

After executing step 211 or step 212, the flow returns to step 201. If the judgment result of step 204 is then OK, processing of the wafer W is permitted in that processing unit 16.

If the judgment result in step 204 is again NG, the judgment result in step 206 is YES (Y), and processing of the wafer W in that processing unit 16 is prohibited. In this case, an alarm is generated by a user interface such as a display or an alarm generator, and an operator is prompted to clean or overhaul that processing unit 16.

In the above specific example, in steps 211 and 212, cleaning operations that can be performed automatically are performed, but this is not limited to this. In steps 211 and 212, cleaning or overhaul of the processing unit 16 may be performed by an operator.

<Specific Example 5>
The cause of particle generation can be inferred from the distribution tendency of particles on the doctor wafer DW. For example, if the particle distribution shown in Fig. 10 is confirmed immediately after the fork of the substrate transfer device 13 removes the doctor wafer DW from the carrier C, it can be determined that the slot of the carrier C is contaminated. In Fig. 10, particles are observed in the part of the doctor wafer DW that contacts the slot of the carrier C.

For example, if a particle distribution like that shown in Figure 11 is confirmed immediately after the forks of the substrate transport device 17 remove the doctor wafer DW from the transfer section 14, it can be determined that the transfer section 14 is contaminated. In this case, it is considered that this is caused by particles that have fallen from the ceiling of the transfer section 14 and are falling down.

12 is confirmed immediately after (or at the beginning of) processing of the doctor wafer DW by the processing unit 16, it can be determined that the three gripping jaws (equally spaced in the circumferential direction) of the spin chuck 30 are contaminated. If the gripping jaws are contaminated, the processing liquid attempting to splash outward from the doctor wafer DW collides with the gripping jaws, causing the particles adhering to the gripping jaws to fall off and contaminate the surface of the doctor wafer DW.

In addition, although not shown, if particles are confirmed near the portion of the doctor wafer DW held by the forks 172 of the substrate transport device 17 (or 13) that comes into contact with the gripping claws immediately after the doctor wafer DW is placed at the destination of transport (e.g., the spin chuck of the processing unit 16), it can be determined that the holding claws 173 of the forks 172 are contaminated.

<Specific Example 6>
13A, 13B, and 13C show the relationship between the position of the nozzle 41 and the amount of particles when the processing liquid is supplied from the nozzle 41 to the rotating doctor wafer DW. The areas shaded in black are areas with a particularly large number of particles. In this case, there are many particles near the landing point of the processing liquid from the nozzle 41. In such a case, it is estimated that the processing liquid being discharged from the nozzle 41 contains a large number of particles.

When a liquid having a certain degree of light-shielding properties is discharged from the nozzle 41 onto the doctor wafer DW, the landing point of the liquid on the doctor wafer DW can be confirmed based on the pixel data acquired by the doctor wafer DW, based on the data format shown in (A) to (C) of Figure 13. In other words, it can be confirmed whether the position control of the nozzle 41 is being performed appropriately.

Figure 13 (D) shows the state during shaking off and drying, where a ring-shaped area with many particles is formed on the peripheral edge of the doctor wafer DW. In this case, it is thought that the drying conditions are inappropriate, or that the mist scattered from the doctor wafer DW is bounced off the collection cup and re-adheres to the doctor wafer DW.

<Detection of particle size using doctor wafer>
Particle detection by the doctor wafer DW will be further described below. Fig. 14 is a schematic diagram showing a state in which a particle P larger than the pixel size exists above a plurality of pixels 105. As shown in Fig. 14, the thickness of the particle P is assumed to be thick at the center and thin at the periphery. In this case, most of the illumination light L irradiated to the center of the particle P is blocked by the particle P and does not reach the pixel 105. On the other hand, a part of the illumination light L irradiated to the periphery of the particle P passes through the particle. Also, the illumination light L may reach the pixel by going around the periphery of the particle P.

Figure 15 is a schematic diagram showing the distribution of the amount of light received by each pixel 105 in the case shown in Figure 14. One black dot corresponds to one pixel 105, and the larger the size of the black dot, the smaller the amount of light received.

Taking the above into consideration, the light intensity when the illumination light L reaches pixel 105 as is (without being blocked by particle P) may be set to 1, and if the light intensity reaching pixel 105 is smaller than a predetermined threshold (e.g., less than 0.8), it may be determined that a particle is present directly above the pixel 105. The threshold may be determined experimentally by comparing data obtained by a proven conventional method (e.g., a method using laser reflection/diffraction) with data obtained using a doctor wafer DW.

When the intensity of light received by one pixel 105 is greater than a threshold value and the intensity of light received by the other pixel 105 is less than the threshold value, it can be determined that part of the contour of the particle P exists between the adjacent pixels 105. By detecting all other adjacent pixels 105 that have such a relationship, the contour of the particle P can be identified.

The threshold may be changed depending on the particle size (which can be determined by the number of consecutive pixels with a light intensity less than, for example, 0.8). For example, when a particle smaller than the pixel size (e.g., about 5 nm) is present on a single pixel, the threshold may be set to, for example, less than 0.5.

As mentioned above, the doctor wafer DW can also detect other defects such as watermarks and scratches, as these defects also prevent illumination light from entering the pixels. Watermarks can be detected using the same detection principles as particles, except that their light transmittance is greater than that of ordinary particles.

When a scratch S occurs on the surface of the protective layer 106 of the doctor wafer DW, the illumination light L is redirected by the scratch S as shown in Figure 16 and hardly reaches the pixel 105 directly below the scratch S. The scratch S extends continuously in a line across a large number of pixels 105. Therefore, when pixels 105 with small amounts of light are connected in a line, it can be determined that there is a scratch above these pixels 105.

<Regeneration of doctor wafers>
It is not preferable to perform an inspection on a doctor wafer DW on which scratches S have occurred on the surface or on which particles that cannot be removed by cleaning are firmly attached. In order to regenerate such a doctor wafer DW, the following regeneration method may be performed.

If the particles are firmly attached or if shallow scratches S are formed, the doctor wafer DW can be reused by thinly scraping off at least the topmost surface of the protective layer 106 using a chemical treatment or CMP treatment. If a hydrophobic thin film is formed on the topmost surface of the protective layer 106, the hydrophobic thin film can be reformed after the above treatment.

If the scratch S is deep and the protective layer 106 of the doctor wafer DW consists of a pixel protection damper 106a and transparent glass (SiOx) 106b, the transparent glass 106b may be completely removed while leaving the pixel protection damper 106a, and then a layer of transparent glass 106b may be formed again.

<Modification of Doctor Wafer>
As described above, the basic function of the doctor wafer DW is to output the electric charge output from each pixel 105 of the light receiving layer 104 to the outside via the wiring layer 102 (including logic circuits, amplifiers, etc.). In this basic configuration, data acquisition and data transmission can be performed only when the electrodes of the doctor wafer DW and external electrodes (for example, electrodes of the gripping jaws of the spin chuck, electrodes of the holding jaws of the forks of the substrate transport mechanism 13, etc.) are in contact with each other.

To solve the above problems, the doctor wafer DW can be added to the basic configuration by combining one or more of the following components, which allows for flexible operation of the doctor wafer DW.
(a) A memory section 107a for temporarily storing pixel data
(b) A power storage unit 107b that stores power for operating the doctor wafer DW.
(c) an antenna section 107c for contactless power supply to the doctor wafer DW (power reception of the doctor wafer DW) or for wireless transmission of data between the doctor wafer DW and an external device (for example, reception of a command to read pixel data and transmission of pixel data to an external device);

The memory unit 107a may be composed of, for example, a DRAM, a RRAM, an MRAM, a NAND type flash memory, etc. The power storage unit 107b may be composed of a battery, a capacitor, etc. The antenna unit may be composed of an amorphous soft magnetic material.

Figure 17 shows a schematic diagram of a doctor wafer DW provided with a memory section 107a in addition to the wiring layer 102, the light receiving layer 104, and the protective layer 106. Figure 18 shows a schematic diagram of a doctor wafer DW provided with a memory section 107a and a power storage section 107b in addition to the wiring layer 102, the light receiving layer 104, and the protective layer 106. Figure 19 shows a schematic diagram of a doctor wafer DW provided with a memory section 107a, a power storage section 107b, and an antenna section 107c in addition to the wiring layer 102, the light receiving layer 104, and the protective layer 106.

20, a nanolens array may be incorporated into the protective layer 106. In this case, individual nanolenses 109 may be positioned directly above each pixel 105. In this case, too, the top surface of the protective layer 106 may be formed of transparent glass (SiOx) or the like.

Instead of providing the light receiving layer 104 on the entire surface of the doctor wafer DW, the light receiving layer 104 may be provided only on a portion of the surface of the doctor wafer DW. For example, as shown in FIG. 21, the light receiving layer 104 may be provided only on a number of lines extending in the diameter direction of the doctor wafer DW. In this way, the amount of data to be handled is reduced, thereby reducing the burden of data transmission and reception and calculation processing. For example, when performing an inspection that only concerns the total amount of particles on the surface of the doctor wafer DW (not the distribution), the inspection efficiency is improved.

Each layer of the doctor wafer DW, such as the wiring layer 102 and the light receiving layer 104, can be formed on a semiconductor wafer using semiconductor device manufacturing technology (film formation technology). However, the doctor wafer DW may also be constructed by attaching a pre-formed imaging device onto a substrate.

In the above embodiment, the electrode 35 is provided on the gripping jaws 34 of the mechanical chuck, but this is not limited to this. If the spin chuck is a vacuum chuck, an electrode may be provided on the vacuum chuck and an electrode may be provided on the central part of the back surface of the doctor wafer DW that contacts the vacuum chuck.

According to the above embodiment, by using the doctor wafer DW, particle level inspection can be performed at various locations in the substrate processing system 1. By installing an illumination device that appropriately irradiates the doctor wafer DW with illumination light, particle level inspection can be performed even during processing and transportation of the doctor wafer DW. In addition, by providing the memory unit 107a, the power storage unit 107b, the antenna unit 107c, etc. on the doctor wafer DW, it is possible to perform particle level inspection at any timing. This makes it possible to easily and quickly identify the cause of particle generation.

Conventional particle level inspection methods using stand-alone particle inspection equipment can only compare particle levels before and after processing and before and after transport, and cannot inspect particle levels during processing or transport. Of course, wet wafers cannot be inspected. Furthermore, in order to identify the cause of particle generation, it is necessary to process many wafers and compare the processing results. Also, it takes a long time to inspect one wafer. Therefore, it takes a very long time to identify the cause of particle generation, and the cost is high. Also, there is a possibility that the wafer will be contaminated while being transported to the stand-alone particle inspection equipment. The above embodiment can solve many of these problems.

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

DW Inspection board 100 Base material 102+104 Imaging element 106 Protective layer 108 Output section (electrode)

Claims (3)

a processing unit for processing a substrate;
a transfer section through which the substrate to be processed in the processing unit is transferred;
a transport mechanism configured to transport the substrate between the loading/unloading section and the processing unit;
an inspection board comprising a plate-shaped base material, an imaging element provided on at least a portion of a surface of the base material, a light-transmitting protective layer made of PFA or PTFA formed on the surface of the imaging element, and an output section that outputs an output of the imaging element to the outside of the inspection board; and an illumination device that irradiates the inspection board with illumination light for inspection in order to detect contaminants adhering to the inspection board when the inspection board is processed by the processing unit or transported by the transport mechanism;
Equipped with
A substrate processing apparatus, wherein the processing unit has a substrate holding part, a nozzle that supplies a processing fluid to the substrate held by the substrate holding part, and a nozzle arm that supports and moves the nozzle, and the lighting device is provided on the nozzle arm . a processing unit for processing a substrate;
a transfer section through which the substrate to be processed in the processing unit is transferred;
a transport mechanism configured to transport the substrate between the loading/unloading section and the processing unit;
an inspection board comprising a plate-shaped base material, an imaging element provided on at least a portion of a surface of the base material, a light-transmitting protective layer made of PFA or PTFA formed on the surface of the imaging element, and an output section that outputs an output of the imaging element to the outside of the inspection board; and an illumination device that irradiates the inspection board with illumination light for inspection in order to detect contaminants adhering to the inspection board when the inspection board is processed by the processing unit or transported by the transport mechanism;
Equipped with
The lighting device is provided on a ceiling of an entrance/exit of the processing unit above a path through which the transport mechanism passes when loading/unloading the substrate into/from the processing unit. The substrate processing apparatus according to claim 1 , further comprising a device including a signal processing device for processing data output from an output section of said test substrate, or a power supply for supplying power for operating said test substrate.