JP6947190B2 - Foreign matter detection device, foreign matter detection method and storage medium - Google Patents

Description

The present invention relates to a storage medium including a foreign matter detecting device for optically detecting foreign matter in a fluid supplied to an object to be processed, a foreign matter detecting method, and a computer program for executing the method.

In the manufacturing process of a semiconductor device, for example, there is a step of performing a liquid treatment on a semiconductor wafer (hereinafter, referred to as a wafer). For example, in the process of forming a resist pattern, various chemicals such as resists are used, and the chemicals are discharged from the chemical bottle onto the wafer through a pipe which is a flow path in which equipment such as a valve is provided and through a nozzle. Will be done. Particles adhering to the piping or each device may be mixed in the chemical solution supplied to the wafer in this way, and bubbles may be generated in the chemical solution. Further, in a chemical solution containing a resin material, for example, a resist, a so-called abnormal polymer component larger than the normal polymer component may be contained.

For example, if particles, air bubbles, or abnormal polymers are mixed in the resist, it may cause development defects. Therefore, these foreign substances are monitored and until the amount of foreign substances falls below the set value, for example, in the supply system including piping. The processing technology for purifying the chemical solution is known. As a method for monitoring foreign matter, there is a method using a particle counter that irradiates a chemical solution in a flow path with a laser beam, receives scattered light from the foreign matter, and measures the amount of the foreign matter.

On the other hand, as the design rules of semiconductor devices become finer, the allowable particle size tends to become smaller and smaller, and a technique for accurately detecting finer foreign substances is required. However, the smaller the foreign matter to be detected, the smaller the S (signal level) / N (noise level), which makes high-precision detection difficult. Further, when trying to detect an abnormal polymer having a large size in a resist, the intensity of the laser beam corresponding to the normal polymer having a small size becomes noise, so that it is difficult to detect the abnormal polymer with high accuracy. For example, Patent Document 1 describes a technique for detecting particles in a chemical solution by transmitting laser light through a flow path, but it is required to detect foreign substances with higher accuracy.

Japanese Unexamined Patent Publication No. 2016-103590

The present invention has been made based on such circumstances, and an object of the present invention is to provide a technique capable of accurately detecting foreign matter flowing in a flow path portion.

The foreign matter detecting device of the present invention is a foreign matter detecting device that detects foreign matter in the fluid supplied to the object to be processed.
A flow path portion through which a fluid, which is a chemical solution containing a polymer, supplied to the object to be treated flows,
A laser light irradiation unit that irradiates a foreign matter detection region in the flow path portion with a laser beam so that the flow direction of the fluid in the flow path portion and the optical path intersect.
A light receiving element that receives light transmitted through the foreign matter detection region and
A condensing lens provided on the optical path between the flow path portion and the light receiving element for condensing on the light receiving element to form a condensing spot.
A detection unit for detecting foreign matter in the fluid based on the signal output from the light receiving element, and
A mask provided with an opening for forming a light receiving region facing the light collecting spot in the light receiving element.
A moving mechanism for moving the mask and
Assuming that the mask is formed and the direction of the optical path formed by the condenser lens is the front-rear direction, the masks are provided so as to overlap each other in the front-rear direction, and each of the masks has an opening, and the movement mechanism causes the left and right sides of the mask to be relative to each other. A plurality of mask members whose positions are changed to change the width of the overlapping region of each of the openings, which is the width of the light receiving region, are provided.
The width of the light receiving region is smaller than the width of the light collecting spot, and the width of the light receiving region is changed according to the type of the chemical solution flowing through the flow path portion.

The foreign matter detecting method of the present invention is a foreign matter detecting method for detecting a foreign matter in a fluid which is a chemical solution containing a polymer supplied to an object to be treated.
A step of supplying the fluid to the flow path portion in order to supply the fluid to the object to be processed, and
A step of irradiating a foreign matter detection region in the flow path portion with a laser beam so that the flow direction of the fluid in the flow path portion and the optical path intersect with the laser light irradiation unit.
A step of receiving light transmitted through the foreign matter detection region by a light receiving element,
A step of forming a condensing spot by condensing light on the light receiving element by a condensing lens provided on an optical path between the flow path portion and the light receiving element.
A step of detecting a foreign substance in the fluid by a detection unit based on a signal output from the light receiving element, and
With
A step of forming a light receiving region facing the light collecting spot in the light receiving element by using a mask provided with an opening, and a step of forming the light receiving region.
The process of moving the mask by the moving mechanism and
When the mask is formed and the direction of the optical path formed by the condenser lens is the front-rear direction, the mask members provided so as to overlap each other in the front-rear direction and each having the opening are provided with each other by the moving mechanism. A step of changing the relative positions on the left and right and changing the width of the overlapping region of the openings, which is the width of the light receiving region, and
The width of the light receiving region is smaller than the width of the light collecting spot, and the step of changing the width of the light receiving region according to the type of the chemical solution flowing through the flow path portion.
It is characterized by having.

The storage medium of the present invention is a storage medium that stores a computer program used in a foreign matter detection device that detects foreign matter in a fluid supplied to an object to be processed.
The computer program is characterized in that a group of steps is set up to execute the foreign matter detection method of the present invention.

In the foreign matter detection device of the present invention, in order to irradiate the foreign matter detection region in the flow path portion with laser light so that the light path intersects with the flow direction of the fluid in the flow path portion through which the fluid supplied to the object to be processed flows. The laser beam irradiation unit and the condensing lens that condenses the light transmitted through the foreign matter detection region to form a condensing spot on the light receiving element, and the light receiving region of the light receiving element facing the condensing spot. The width is smaller than the width of the focused spot. With this configuration, it is possible to suppress the inclusion of noise in the signal output from the light receiving element and detect foreign matter with high accuracy.

It is a schematic block diagram of the coating and developing apparatus which concerns on embodiment of this invention. It is a perspective view of the resist coating module included in the coating and developing apparatus. It is a schematic block diagram of the foreign matter detection unit included in the coating and developing apparatus. It is a perspective view of the constituent member of the flow path of the chemical liquid which constitutes the foreign matter detection unit. It is a top view of the foreign matter detection unit. It is a front view of the light detection part and a mask which constitute the foreign matter detection unit. It is a block diagram which shows the circuit structure included in the foreign matter detection unit. It is the schematic which shows the optical path in the foreign matter detection unit. It is a top view which shows the optical path from the flow path to the light receiving element which forms the light detection part. It is a graph for demonstrating the appropriate opening width of the mask. It is a timing chart which shows the operation of each part of a coating and developing apparatus. It is a top view of the coating and developing apparatus. It is a schematic longitudinal side view of the coating and developing apparatus. It is the schematic which shows the structure of another foreign matter detection unit. It is the schematic which shows the structure of the light receiving part of the foreign matter detection unit. It is a graph which shows the result of the evaluation test. It is a graph which shows the result of the evaluation test.

FIG. 1 is a schematic view of a coating / developing device 1 to which the foreign matter detecting device of the present invention is applied. The coating / developing apparatus 1 is a resist coating module 1A, 1B, an antireflection film forming module 1C, 1D, a protective film forming module 1E, 1F, which respectively supplies a chemical solution to a substrate, for example, a wafer W, which is an object to be processed. It has. These modules 1A to 1F (resist coating modules 1A, 1B, antireflection film forming modules 1C, 1D, protective film forming modules 1E, 1F) are chemical solution supply modules for supplying a chemical solution to the wafer W for processing. The coating and developing apparatus 1 supplies various chemicals to the wafer W by these modules 1A to 1F, and forms an antireflection film, a resist film, and a protective film for protecting the resist film at the time of exposure in order. After that, for example, the wafer W exposed to immersion is developed.

The modules 1A to 1F are provided with a chemical solution supply path, and the coating / developing device 1 is configured to detect foreign matter in the chemical solution flowing through the supply path. The chemical solution that has flowed through the above supply path is supplied to the wafer W. Therefore, the supply of the chemical solution to the wafer W and the detection of foreign matter are performed in parallel with each other. Foreign matter includes, for example, particles, air bubbles, and an abnormal polymer having a larger particle size than the normal polymer constituting the chemical solution. Specifically, the detection of foreign matter is the detection of the total number of foreign matter flowing in a predetermined detection area of the flow path of the chemical solution and the size of each foreign matter during a predetermined period, for example. The coating / developing apparatus 1 is provided with a light supply unit 2, and the light supply unit 2 is provided with a foreign matter detection unit provided in modules 1A to 1F by a fiber 23 for laser light having a wavelength of, for example, 532 nm output from a light source 21. Guide light to 4.

Modules 1A to 1F are configured in substantially the same manner, and here, a schematic configuration of the resist coating module 1A shown in FIG. 1 will be described. The resist coating module 1A includes, for example, 11 nozzles 11A to 11K, of which 10 nozzles 11A to 11J discharge a resist as a chemical solution onto the wafer W to form a resist film as a coating film. The nozzle 11K discharges thinner to the wafer W. Thinner is a chemical solution for pre-wetting that is supplied to the wafer W before the resist is supplied to enhance the wettability of the resist, and is a solvent for the resist.

The downstream ends of the chemical liquid supply pipes 12A to 12J forming the chemical supply passages are connected to the nozzles 11A to 11J, and the upstream ends of the chemical liquid supply pipes 12A to 12J are connected to the resist supply sources 13A to 13J via the valve V1. They are connected to each other. The resist supply sources 13A to 13J include, for example, a bottle in which the resist is stored and a pump for pumping the resist supplied from the bottle to the nozzles 11A to 11J. The types of resists stored in the bottles of the supply sources 13A to 13J are different from each other, and one type of resist selected from 10 types of resists is supplied to the wafer W.

The downstream end of the chemical solution supply pipe 12K is connected to the nozzle 11K, and the upstream end of the chemical solution supply pipe 12K is connected to the supply source 13K via the valve V1. The supply source 13K is configured in the same manner as the supply sources 13A to 13J, except that the thinner is stored instead of the resist. That is, when processing the wafer W, the timing at which the chemical solution flows through the chemical solution supply pipes 12A to 12K is different from each other. The chemical solution supply pipes 12A to 12K are made of a flexible material, for example, a resin, and are configured so as not to interfere with the movement of the nozzles 11A to 11K, which will be described later. A cuvette 15A to 15K is interposed between the nozzles 11A to 11K and the valve V1 in the chemical solution supply pipes 12A to 12K. The cuvettes 15A to 15K are configured as a flow path portion for measuring foreign matter, and the foreign matter passing through the inside thereof is detected. The cuvettes 15A to 15K will be described in detail later.

FIG. 2 shows an example of a more detailed configuration of the resist coating module 1A. In the figure, 31 and 31 are spin chucks, which horizontally attract and hold the central portion of the back surface of the wafer W and rotate the held wafer W around the vertical axis. In the figure, 32 and 32 are cups, which surround the lower side and the side surface of the wafer W held by the spin chucks 31 and 31, and suppress the scattering of the chemical solution. Reference numeral 33 denotes a rotating stage that rotates around a vertical axis, and a vertical column 34 that is movable in the horizontal direction and holders 35 for nozzles 11A to 11K are provided on the rotating stage 33. Reference numeral 36 denotes an elevating part that can be moved up and down along the support column 34, and reference numeral 37 denotes an arm that can move the raising and lowering part 36 in the horizontal direction orthogonal to the moving direction of the support column 34. A attachment / detachment mechanism 38 for nozzles 11A to 11K is provided at the tip of the arm 37. The nozzles 11A to 11K move between the spin chuck 31 and the holder 35 by the cooperative operation of the rotary stage 33, the support column 34, the elevating part 36, and the arm 37.

A foreign matter detection unit 4 is provided on the side of the rotary stage 33 and the cup 32 so as not to interfere with the moving arm 37 or the support column 34. The foreign matter detection unit 4, the above-mentioned light supply unit 2, and the control unit 6 described later constitute the foreign matter detection device of the present invention. FIG. 3 shows a plan view of the foreign matter detection unit 4. The foreign matter detection unit 4 includes a laser light irradiation unit 51, a light receiving unit 52, and a flow path array 16, and is configured as, for example, a light scattering type particle counter using forward scattered light. That is, when the light receiving element receives the scattered light generated by the foreign matter, the foreign matter is detected based on the change in the signal output from the light receiving element.

The downstream end of the fiber 23 is connected to the laser beam irradiation unit 51 via a collimator 42. For example, during the operation of the coating and developing apparatus 1, light is constantly supplied to the fiber 23 from the light supply unit 2, and the light is supplied to the flow path array 16 by opening and closing the optical path of the shutter 41 described later, and the flow path. The state in which the supply of light to the array 16 is stopped is switched. The fiber 23 has flexibility so as not to hinder the movement of the laser light irradiation unit 51, which will be described later.

The flow path array 16 will be described with reference to the perspective view of FIG. The flow path array 16 forming the flow path portion of the chemical solution is made of quartz, is configured as a rectangular horizontally long block, and has 11 through-holes formed in each of the vertical directions. The through-holes are arranged along the length direction of the flow path array 16, and each through-hole and the wall portion around the through-hole are configured as the above-mentioned cuvettes 15A to 15K. Therefore, the cuvettes 15A to 15K form an upright tube, and the chemical solution flows from the upper side to the lower side through each through hole constituting the cuvettes 15A to 15K. Each through hole of the cuvette 15A to 15K is a flow path 17A to 17K. The flow paths 17A to 17K are configured in the same manner as each other, and are interposed in the chemical supply pipes 12A to 12K as described above.

The explanation will be continued by returning to FIG. The laser light irradiation unit 51 and the light receiving unit 52 are provided so as to face each other with the flow path array 16 sandwiched from the front and back. In the figure, 43 is a stage that supports the laser light irradiation unit 51 and the light receiving unit 52 from the lower side of the flow path array 16, and is configured to be movable in the left-right direction by a drive mechanism (not shown). By moving the stage 43 in this way, the laser light irradiating unit 51 can irradiate the light guided from the fiber 23 to one of the selected flow paths 17A to 17K, and receives light. The section 52 irradiates the flow path 17 in this way, and receives the light transmitted through the flow path 17. That is, an optical path is formed in the flow path 17 so as to intersect the flow direction of the chemical solution.

FIG. 5 is a schematic configuration diagram of the laser light irradiation unit 51 and the light receiving unit 52. For convenience of explanation, the direction from the laser light irradiation unit 51 to the light receiving unit 52 is set to the rear. The laser light irradiation unit 51 includes an optical system, and the optical system includes, for example, a condenser lens 53. Although not shown in FIG. 5, the laser light irradiation unit 51 is provided with the shutter 41 as shown in FIG.

The collimator 42 irradiates the laser beam in the horizontal direction toward the rear side. The shutter 41 has a shielding position that shields the optical path between the collimator 42 and the condensing lens 53 (indicated by a chain line in FIG. 3) and an open position that retracts from the optical path (indicated by a solid line in FIG. 3). Moves to and from (is) and opens and closes the optical path. The condensing lens 53 includes a cylindrical lens or a lens called, for example, a Powell lens or a laser line generator lens, and condenses the laser light emitted from the collimator 42 into the flow path 17A, and the flow direction of the chemical solution with respect to the cross section of the optical path. The laser beam is flattened so that the length in the direction orthogonal to the flow direction is longer than the length of the lens. On the front side of the condenser lens 53, the cross section of the optical path (cross section viewed in the front-rear direction) is, for example, a substantially circular circle, and the cross section of the optical path in the cuvette 15 by the condenser lens 53 is, for example, It has an elliptical shape with a major axis along the left-right direction.

In the optical path formed in the flow path 17A, the condensing region having a relatively high energy density becomes the foreign matter detection region 50, and the foreign matter that has entered the detection region 50 is detected. Since the optical path is formed in the flow path 17A as described above, the detection area 50 is horizontally long in the left-right direction, and the ratio of the area of the detection area 50 to the area of the flow path 17A when viewed in a plane is relatively large. .. By forming such a detection region 50, the ratio of the number of detected foreign substances to the total number of foreign substances flowing in the flow path 17A is increased.

Subsequently, the light receiving unit 52 will be described. The light receiving unit 52 includes an optical system 54, a mask 61, and a photodetector 40, which are arranged in order from the front side to the rear side. The optical system 54 includes an objective lens 56 and a condenser lens 57 arranged on the front side and the rear side, respectively. The light transmitted through the cuvette 15A becomes parallel light by the objective lens 56, and the light is detected by the condenser lens 57. The light is focused on the unit 40.

Subsequently, the light detection unit 40 will be described with reference to the front view of FIG. Note that FIG. 6 shows the photodetector 40 viewed from the front position of the mask 61 toward the rear. The photodetector 40 is composed of 64 light receiving elements, each of which is composed of a photodiode, for example, and each light receiving element is similarly configured. The light receiving elements are arranged at intervals from each other so as to form a matrix of, for example, 2 × 32. The light receiving element arranged on the upper side is referred to as a light receiving element 45A, and the light receiving element arranged on the lower side is referred to as a light receiving element 45B. The left and right widths of the light receiving elements 45A and 45B shown by L4 in the figure are 53 μm in this example. The cross section of the optical path irradiated to the light detection unit 40 is also a flat ellipse whose long side is along the left-right direction, and the light receiving element 45A is in the upper half of the optical path and the light receiving element 45B is in the lower half of the optical path. These light receiving elements 45A and 45B are arranged so that the light receiving elements 45A and 45B are respectively located. The light receiving element 45A and the light receiving element 45B at the same position in the left-right direction form one set. These light receiving elements 45A and 45B may be indicated with channel (ch) numbers as 1 channel, 2 channels, 3 channels ... 32 channels (ch) in order from the left side when viewed from the rear side. ..

The foreign matter detection unit 4 includes a total of 32 circuit units 46 provided corresponding to the channels of the light receiving elements 45A and 45B. Explaining the circuit unit 46 with reference to FIG. 7, the circuit unit 46 is provided after the transimpedance amplifiers (TIA) 47A and 47B and the TIA 47A and 47B, which are provided after the light receiving element 45A and the light receiving element 45B, respectively. The difference circuit 48 is provided. The light receiving element 45A and the light receiving element 45B supply currents corresponding to the intensity of the received light to the TIA 47A and 47B, and the TIA 47A and 47B output voltage signals corresponding to the supplied currents to the difference circuit 48, respectively. The difference circuit 48 outputs a voltage signal of the difference between the voltage signal from the TIA47A and the voltage signal from the TIA47B to the control unit 6 described later. The control unit 6 detects foreign matter based on the signal output from the difference circuit 48. The reason why the foreign matter is detected based on the signal corresponding to the difference between the outputs of the light receiving elements 45A and 45B is to remove the noise commonly detected by the light receiving elements 45A and 45B. The circuit unit 46 may also be indicated with the same channel number as the channel numbers of the light receiving elements 45A and 45B to be connected.

The relationship between the light receiving elements 45A and 45B and the cuvette detection region 50 will be described in more detail with reference to the schematic diagram of FIG. The arrow of the alternate long and short dash line in the figure indicates the optical path from the laser light irradiation unit 51 to the light receiving element 45A group when light is irradiated toward the flow path 17A of the cuvette 15A. Note that the mask 61 is omitted in FIG. 8 for convenience of explanation. When viewed toward the front side in the optical path of the flow path 17A, each of the divided detection areas in which the upper half of the detection area 50, which is the condensing area, is divided into 32 pieces in the length direction, is divided and detected in order from the right end. It shall be referred to as a divided detection area of the area to 32ch. The left and right widths of one division detection region shown by L21 in the figure are, for example, 0.85 μm, and each division detection region is designated by reference numeral 59.

In the optical system 54, the 1ch division detection area 59 and the 1ch light receiving element 45A have a one-to-one correspondence, and the 2ch division detection area 59 and the 2ch light receiving element 45A have a one-to-one correspondence, and the 3ch division. The detection region 59 and the light receiving element 45A of 3ch have a one-to-one correspondence, and similarly, the divided detection region 59 of the same channel and the light receiving element 45A have a one-to-one correspondence. That is, the 1ch light receiving element 45A is irradiated with almost all of the reaction light (light perturbed by the reaction) generated by reacting with the foreign matter in the 1ch divided detection region 59, and the 2ch light receiving element 45A is irradiated with 2ch. Almost all of the reaction light (light perturbed by the reaction) generated by reacting with a foreign substance in the divided detection region 59 is irradiated. In order to receive light in this way, for example, 85% or more of the laser light transmitted through the divided detection region 59 of each channel is received by the light receiving element 45A of the corresponding channel. In FIG. 8, the solid line arrow and the dotted line arrow show the optical path of the reaction light emitted from the divided detection regions 59 of different channels to the light receiving elements 45A of different channels.

By performing the light irradiation in this way, a signal corresponding to the foreign matter that has entered the detection region 50 is generated from the light receiving element 45A of any one channel. For example, if the reaction light does not irradiate only the light receiving element 45A of the corresponding channel but enters the light across the light receiving element 45A of another channel, the current level flowing through the light receiving element 45A becomes low and the detection accuracy becomes low. .. That is, by configuring the divided detection region 59 and the light receiving element 45A so as to correspond to each other as described above, the detection accuracy of foreign matter is improved.

Similarly, it is assumed that each of the divided detection areas 59 in which the lower half of the detection area 50, which is the condensing area, is divided into 32 pieces in the length direction is referred to as a 1ch divided detection area 59 to 32ch divided detection area 59. The divided detection region 59 of one channel corresponds to the light receiving element 45B of one channel. That is, the optical system 54 is configured so that the reaction light of the divided detection region 59 of one channel is irradiated to the light receiving element 45B of one channel.

Further, as described above, the configuration so as to have the light receiving elements 45A and 45B of a plurality of channels is to suppress the energy of the laser light received by one light receiving element 45 (45A and 45B), so that the photons of the laser light can be generated. This is to reduce shot noise caused by fluctuations and improve the signal-to-noise ratio (S / N), and by suppressing the number of normal polymers flowing in the detection region corresponding to one light receiving element 45, it is caused by the polymer. This is also to suppress the noise generated and improve the SN ratio. Although the optical path when the detection region 50 is formed in the cuvette 15A is illustrated, when the detection region 50 is formed in the other cuvettes 15B to 15K, the optical path is similarly formed and the foreign matter is detected. It is said.

Here, the mask 61 will be described in more detail. As shown in FIG. 6, the mask 61 includes, for example, 32 vertically elongated openings 62, which are arranged along the left and right sides and in front of the light receiving elements 45A and 45B of each channel. To position. The left and right opening widths L5 of the opening 62 are smaller than the widths L4 of the light receiving elements 45A and 45B. Therefore, a part of the light emitted from the divided detection region 59 to the light receiving elements 45A and 45B is shielded from light, and only the other part is received by the light receiving elements 45A and 45B. The region of the light receiving elements 45A and 45B that overlaps the opening 62 faces the condensing spot 63 described later, and forms a light receiving region for outputting a signal from the light receiving elements 45A and 45B.

In FIG. 9, the optical path from the divided detection region 59 of 3ch to the light receiving element 45A of 3ch in the upper half of the detection region 50 is schematically shown by a dotted line. 9 and 6 show a laser beam focusing spot 63 formed by irradiating the light receiving element 45A of 3ch from the divided detection region 59 of 3ch when the mask 61 is not provided. As described above, almost all of the light in one divided detection region 59 is applied to the light receiving element 45A corresponding to the divided detection region 59, so that the left and right widths L6 of the condensing spot 63 are the light receiving elements 45A and 45B. It is the same as the width L4, for example, 53 μm. That is, the width L5 of the opening 62 of the mask 61 is smaller than the width L6 of the condensing spot 63. Therefore, when viewed in the front-rear direction, which is the formation direction of the optical path, the area of the light-receiving region of the light-receiving elements 45A and 45B is smaller than the area of the light-collecting spot 63.

The light receiving elements 45A and 45B other than the light receiving elements 45A of 3ch also face the light condensing spot 63 formed by similarly irradiating light from the corresponding divided detection region 59. That is, the condensing lens 57 irradiates light so that a condensing spot is formed so as to straddle the light receiving elements 45A and 45B of each channel, and the condensing spot 63 shown in FIGS. 6 and 9 is the condensing spot 63. As described above, the region corresponding to one divided detection region 59 in the condensing spot straddling the light receiving elements 45A and 45B is shown. That is, in this example, the 64 light receiving elements 45 are each irradiated with light from the 64 divided detection regions 59 that each constitute the foreign matter detection region to form the condensing spot 63, and the width of each condensing spot 63 is increased. It is smaller than the width of each light receiving element 45.

The reason for providing the above mask 61 will be described. The resist flowing through the channels 17A to 17J contains a normal polymer for forming a resist film, and when this polymer passes through the division detection region 59, the light receiving elements 45A and 45B are affected by the polymer. The scattered light is irradiated, and background noise is generated in the signals output from the light receiving elements 45A and 45B. The larger the split detection region 59 corresponding to one light receiving element 45A or 45B, the larger the amplitude of the noise signal because it is affected by this normal polymer.

Even if a foreign matter passes through the divided detection region 59 and a foreign matter detection signal is output, it is difficult to detect a signal having an amplitude smaller than the amplitude of this noise signal. That is, the noise signal determines the minimum measurable particle size (minimum measurable particle size) of the foreign matter. Therefore, a light receiving area capable of outputting a signal by providing the above mask 61 to make the left and right widths of the light receiving elements 45A and 45B smaller than the left and right widths of the light collecting spot 63 and receiving light by the light receiving elements 45A and 45B. Reduces the area of the polymer and reduces the number of polymers detected. As a result, the level of the noise signals output from the light receiving elements 45A and 45B is suppressed to improve the SN ratio, relatively small foreign matter can be detected, and the foreign matter detection accuracy is improved.

By the way, since the amplitude of the noise signal is affected by the size of the polymer contained in the chemical solution and the difference in the refractive index between the polymer and the solvent, an appropriate value of the opening width L5 of the mask 61 is determined by the chemical solution. It depends on the type. Here, as a representative, assuming that the opening width L5 corresponding to the resist flowing through the flow path 17A is set, the setting method will be described with reference to the graph of FIG. The horizontal axis of the graph indicates the aperture width L5 (unit: μm), and therefore indicates the width of the light receiving region. The vertical axis of the graph is the amplitude of the voltage signal output from the light receiving element 45A or 45B.

The curve A1 of the graph shows the correspondence between the aperture width L5 and the amplitude of the foreign matter having the smallest particle size among the foreign substances to be detected in the resist, and shows the characteristics of the signal output from the light receiving element. Corresponds to the representing curve. As shown in the graph, the amplitude of the curve A1 gradually increases as the opening width L5 increases, but the increase in the amplitude is gradually suppressed and eventually reaches a plateau. The correspondence between the aperture width L5 and the amplitude of the noise output from the light receiving element 45A or 45B is expressed as a linear function as shown by the straight line A2 in the graph, and the amplitude of the noise increases as the aperture width L5 increases. Becomes larger. The straight line A2 corresponds to a straight line representing the characteristics of the noise signal output from the light receiving element. In this way, it has been clarified by the inventor's experiment that the characteristics of the foreign matter detection signal and the characteristics of noise are different from each other. The curves A1 and the straight line A2 are calculated by, for example, the least squares method based on the data acquired by the experiment.

If the amplitude of the foreign matter detection signal is smaller than the amplitude of the noise, it is difficult to distinguish between the detected signal and the noise. Set. That is, the range of B1 to B2 shown in the graph is a candidate for the opening width L5. By the way, as described above, the smaller the opening width L5, the smaller the amount of the polymer detected in the flow path 17A, and the noise can be suppressed. However, as shown in the graph, the slope of the curve A1 becomes steeper as the opening width L5 becomes smaller, and when the slope of the curve A1 becomes larger than the slope of the straight line A2, the detection signal drops faster than the noise. Difficult to improve. Therefore, it is preferable to set the opening width L5 so that the slope of the tangent line of the curve A1 and the slope of the straight line A2 are aligned with each other within the range of the above B1 to B2.

The fact that the above slopes are aligned with each other means that the slope of the tangent line of the curve A1 is included in the range of 0.95 × (Y1 / X1) to 1.05 × (Y1 / X1), assuming that the slope of the straight line A2 is Y1 / X1. Say that That is, in the curve A1, if the inclination is included in the above range when the tangent line of the point corresponding to the set opening width L5 is drawn, the opening width L5 set in that way is a preferable value. In the figure, as an example of a tangent line whose slope is aligned with the straight line A2, the tangent line of the curve A1 whose slope matches the slope of the straight line A2 is shown as A3, and the opening width L5 corresponding to this tangent line A3 is shown as B3. There is. As described above, the appropriate opening width L5 differs depending on the type of the chemical solution, but the appropriate opening width L5 is the same for the resists flowing through the flow paths 17A to 17J, and in this embodiment, these are the same. It is assumed that the mask 61 is shared by the flow paths 17A to 17J.

Subsequently, a control unit 6 (see FIG. 1), which is a foreign matter detecting unit provided in the coating / developing device 1, will be described. The control unit 6 is composed of, for example, a computer, and has a program storage unit (not shown). In this program storage unit, processing of the wafer W in each module, detection of foreign matter based on the signal output from each channel of the light receiving element as described above, coating by a transport mechanism described later, in the developing apparatus 1 A program in which instructions (step groups) are set so that each operation such as transfer of the wafer W of the above is performed is stored. By the program, control signals are output from the control unit 6 to each unit of the coating and developing apparatus 1, so that each of the above operations is performed. This program is stored in the program storage unit in a state of being stored in a storage medium such as a hard disk, a compact disk, a magnet optical disk, or a memory card.

Explaining the modules other than the resist coating module 1A shown in FIG. 1, the resist coating module 1B is configured in the same manner as the module 1A. The antireflection film forming modules 1C and 1D and the protective film forming modules 1E and 1F are modules 1A, except that, for example, a chemical solution for forming an antireflection film and a chemical solution for forming a protective film are supplied instead of resist and thinner. It is configured in the same manner as 1B. The chemical solution for forming the antireflection film contains a polymer like the resist. For example, in the modules 1C to 1F (antireflection film forming modules 1C, 1D and protective film forming modules 1E, 1F), the chemical solution is supplied to the wafer W in the same manner as in the modules 1A and 1B.

Subsequently, with reference to the timing chart of FIG. 11, the processing of the wafer W and the detection of foreign matter performed in the resist coating module 1A will be described. In this timing chart, the timing at which the pressure of the pump at the supply source 13 of 13A to 13K is set, and the one nozzle 11 corresponding to the supply source 13 of 11A to 11K moves by the arm 37. Timing, timing of opening and closing valve V1 of the chemical solution supply pipe 12 corresponding to one of the supply sources 13 of 12A to 12K, a state in which the laser light is irradiated from the laser light irradiation unit 51, and the irradiation of the laser light is stopped. The timing at which the state is switched and the timing at which the control unit 6 acquires signals from each channel of the light detection unit 40 are shown. The timing at which the laser beam irradiation state and the irradiation stop state can be switched can be said to be the timing at which the shutter 41 of the foreign matter detection unit 4 opens and closes.

Actually, thinner and resist are applied to the wafer W in this order, but for convenience of explanation, the operation when the resist is applied will be described first. First, in a state where the wafer W is conveyed and held on the spin chuck 31, for example, the nozzle 11A is conveyed onto the wafer W, and the pump of the supply source 13A sucks the resist, thereby achieving a predetermined pressure. The settling is started so as to be (time t1). For example, in parallel with the movement of the nozzle and the operation of the pump, the laser light irradiation unit 51 and the light receiving unit 52 move to positions sandwiching the cuvette 15A. At this time, the shutter 41 of the foreign matter detection unit 4 is closed.

The nozzle 11A stands still on the wafer W (time t2), and the wafer W is in a state of rotating at a predetermined rotation speed. Subsequently, the valve V1 of the chemical solution supply pipe 12A is opened, the resist is pumped from the pump toward the nozzle 11A at a predetermined flow rate, the shutter 41 is opened, the laser light is irradiated from the laser light irradiation unit 51, and the cuvette 15A is irradiated. Is transparent. That is, the detection region 50 is formed in the flow path 17A of the cuvette 15A as described with reference to FIGS. 8 and 9, and the light receiving portions 45A and 45B are irradiated with light (time t3). As described with reference to FIG. 9, a part of the light in the divided detection region 59 constituting the detection region 50 is shielded by the mask 61, and is included in the signal output from the light receiving elements 45A and 45B to the circuit unit 46. The noise caused by the normal polymer in the resist is small.

Then, the pressure-fed resist passes through the cuvette 15A and is discharged from the nozzle 11A to the center of the wafer W. When the opening degree of the valve V1 increases and reaches a predetermined opening degree, the increase in the opening degree stops (time t4). After that, the control unit 6 starts acquiring the output signal from the circuit unit 46 of each channel (time t5). When the foreign matter flows through the flow path 17A and flows from the upper side to the lower side in the detection area 50, the signal corresponding to the foreign matter is output from the light receiving element 45A or the light receiving element 45B of the channel corresponding to the divided detection area 59 through which the foreign matter has flowed. , The level of the output signal from the circuit unit 46 changes. After that, the acquisition of the output signal from the light receiving element 45 of each channel by the control unit 6 is stopped (time t6), the shutter 41 is subsequently closed, the light irradiation from the laser light irradiation unit 51 is stopped, and the chemical solution supply tube is stopped. The valve V1 of 12A is closed (time t7), and the discharge of the resist to the wafer W is stopped. The discharged resist is spread on the peripheral edge of the wafer W by centrifugal force to form a resist film.

During the above time t5 to t6, foreign matter is counted for each channel of the light receiving element 45 based on the output signal acquired from the circuit unit 46 of each channel. Further, based on this output signal, the particle size of the foreign matter is measured and classification is performed. That is, the number of foreign substances is counted for each of a plurality of ranges set for the particle size. Then, the number of foreign substances detected for each channel is totaled, and the number of foreign substances detected in the entire detection area 50 (referred to as the total number of foreign substances) is calculated. After that, it is determined whether or not the total number of foreign substances is equal to or greater than the threshold value and whether or not the number of foreign substances larger than a predetermined particle size is equal to or greater than the threshold value.

Then, when it is determined that the total number of the above foreign substances is equal to or greater than the threshold value, or when it is determined that the number of foreign substances larger than the predetermined particle size is equal to or greater than the threshold value, an alarm is output and the module is output. The operation of 1A is stopped, and the processing of the wafer W is stopped. Specifically, this alarm is, for example, a predetermined display on a monitor constituting the control unit 6 or a predetermined audio output from a speaker constituting the control unit 6. Further, the output of this alarm includes, for example, a display or a voice output for notifying the user of the cuvette 15 in which an abnormality is detected among 15A to 15K. If it is determined that the total number of foreign substances is not equal to or greater than the threshold value and the number of foreign substances larger than the predetermined particle size is not equal to or greater than the threshold value, no alarm is output and the operation of module 1A is stopped. Is not done either. It should be noted that each of the above calculations and each determination is performed by the control unit 6 forming the counting unit.

When discharging the thinner to the wafer W, the nozzle 11K is conveyed onto the wafer W instead of the nozzle 11A, the pump of the supply source 13K operates instead of the pump of the supply source 13A, and the chemical solution supply pipe 12A. Each part operates according to the timing chart of FIG. 11, except that the valve V1 of the chemical supply pipe 12K opens and closes instead of the valve V1 of the above, and the cuvette 15K is irradiated with light instead of the cuvette 15A. .. By the operation, foreign matter in the thinner is detected in parallel with the supply of the wafer W to the thinner. Although thinner does not contain a polymer, noise is reduced by appropriately setting the opening width L5 of the mask 61 as in the case of detecting foreign matter in the resist, as shown in the evaluation test described later. It has been confirmed that the detection accuracy of foreign matter can be improved. The thinner supplied to the wafer W is supplied to the entire surface of the wafer W by the rotation of the wafer W in the same manner as the resist. The resist supplied through the flow path 17A is supplied to the wafer W to which thinner is supplied in this way.

When a resist contained in a supply source other than the supply source 13A is supplied to the wafer W after the thinner is supplied to the wafer W, the nozzle for discharging the resist to be used is conveyed onto the wafer W. The pump of the source corresponding to the resist used operates, the valve V1 of the supply pipe corresponding to the resist used opens and closes, and the cubet corresponding to the resist used is irradiated with light. Except for this, the same operation as when the resist of the supply source 13A is supplied to the wafer W is performed.

In the detection of foreign matter described in the chart of FIG. 11 above, in order to improve the measurement accuracy by detecting the foreign matter in a state where the liquid flow of the cuvette 15A is stable, the timing of opening and closing the valve V1 as described above is used. , The timing at which the control unit 6 starts and ends the acquisition of the output signal is different from each other. For example, the time t4 to t5 is 10 milliseconds to 1000 milliseconds, and the time t6 to t7 is 10 milliseconds to 100 milliseconds. Although the operation of the module 1A has been described as a representative, the chemical solution is supplied to the wafer W and the foreign matter is detected in the other modules 1B to 1F as well as the module 1A.

According to the coating / developing apparatus 1, the cuvettes 15A to 15K, which are a part of the flow path of the resist supplied to the wafer W and form the measurement region of the foreign matter in the resist, and the laser light irradiation unit 51 are irradiated. The width of the light receiving elements 45A and 45B that receive the light transmitted through the cuvettes 15A to 15K and the light receiving element 63 corresponding to each divided detection area 59 of the detection area 50 formed in the cuvettes 15A to 15K. A mask 61 is provided to reduce the width of the region where the light of 45A and 45B can be detected. Therefore, the level of noise included in the output signals from the light receiving elements 45A and 45B can be suppressed, and as a result, the SN ratio of the output signals can be increased. Therefore, the control unit 6 provided in the coating / developing device 1 can detect foreign matter in the resist with high accuracy. By the way, the appropriate correspondence between the width of the condensing spot 63 and the widths of the light receiving elements 45A and 45B is determined according to the chemical solution. That is, when the mask 61 is not provided, the widths of the appropriate condensing lens 57 and the light receiving elements 45A and 45B are different for each chemical solution, and therefore, these widths are adjusted in order to obtain an appropriate correspondence as described above. However, when the mask 61 is provided as in the present embodiment, the opening width (slit width) of the mask 61 is simply adjusted according to the chemical solution used in the apparatus to obtain the above-mentioned appropriate correspondence. be able to. Therefore, there is an advantage that the size of the condenser lens 57 and the light receiving elements 45A and 45B can be prevented from increasing in size, the device configuration can be simplified, and the manufacturing cost of the device can be reduced.

Further, by detecting the foreign matter in this way, the cleanliness of the resist supplied to the wafer W is monitored. When the cleanliness of the resist falls below a predetermined standard, the operation of the module is stopped as described above, whereby the processing of the subsequent wafer W is stopped in the module. Therefore, it is possible to prevent the resist having low cleanliness from being supplied to the subsequent wafer W, and thus it is possible to prevent the yield from being lowered. Further, since the supply pipe 12 in which the foreign matter is detected is identified from the chemical solution supply pipes 12A to 12K, the user of the coating and developing apparatus 1 can promptly perform maintenance and repair after the operation of the module is stopped. Therefore, it is possible to suppress that the operation of the module is stopped for a long time, and as a result, it is possible to suppress a decrease in the productivity of the semiconductor product in the coating / developing apparatus 1.

Further, when it is determined that the total number of foreign substances passing through the detection region 50 is equal to or more than the threshold value as described above, and / or the number of foreign substances having a particle size larger than a predetermined particle size is the threshold value. The measures to be taken when it is determined that the above is the case are not limited to the output of the alarm and the stop of the operation of the module. For example, among the resist supply sources 13A to 13J, the resist is supplied to the nozzle 11 as the cleaning liquid of the supply pipe 12 from the supply source 13 corresponding to the cuvette 15 in which the determination is made, and is included in the chemical liquid supply pipe 12. The foreign matter is removed from the nozzle 11. That is, the chemical solution supply pipe 12 is automatically cleaned. After this operation, the processing may be restarted for the subsequent wafer W.

Subsequently, a specific configuration example of the coating / developing apparatus 1 will be described with reference to FIGS. 12 and 13. 12 and 13 are a plan view and a schematic longitudinal side view of the coating and developing apparatus 1, respectively. The coating / developing device 1 is configured by linearly connecting the carrier block D1, the processing block D2, and the interface block D3. The exposure apparatus D4 is connected to the interface block D3. The carrier block D1 coats the carrier C, carries it in and out of the developing apparatus 1, and conveys the wafer W from the carrier C via the carrier C mounting table 71, the opening / closing portion 72, and the opening / closing portion 72. It is provided with a mechanism 73.

The processing block D2 is configured by laminating the first to sixth unit blocks E1 to E6 that perform liquid treatment on the wafer W in order from the bottom. The unit blocks E1 to E6 are partitioned from each other and are provided with transfer mechanisms F1 to F6, respectively, and the wafer W is transferred and processed in parallel with each other in each unit block E (first to sixth unit blocks E1 to E6). Is done. Here, the third unit block E3 as a representative of the unit blocks will be described with reference to FIG. The transport region 74 is formed so as to extend from the carrier block D1 toward the interface block D3, and the transport mechanism F3 is provided in the transport region 74. Further, when viewed from the carrier block D1 toward the interface block D3, the shelf unit U is arranged on the left side of the transport area 74. The shelf unit U includes a heating module. Further, the resist coating module 1A and the protective film forming module 1E are provided along the transport region 74 on the right side of the transport region 74 when viewed from the carrier block D1 to the interface block D3.

The fourth unit block E4 is configured in the same manner as the third unit block E3, and is provided with a resist coating module 1B and a protective film forming module 1F. The unit blocks E1 and E2 have the same configuration as the unit blocks E3 and E4, except that the resist coating modules 1A and 1B and the antireflection film forming modules 1C and 1D are provided in place of the protective film forming modules 1E and 1F, respectively. Will be done. The unit blocks E5 and E6 include a developing module that supplies a developing solution to the wafer W to develop a resist film. The developing module is configured in the same manner as the modules 1A to 1F except that the developing solution is supplied to the wafer W as a chemical solution.

On the carrier block D1 side of the processing block D2, a tower T1 extending vertically across the unit blocks E1 to E6 and an elevating and lowering transfer mechanism 75 for transferring the wafer W to the tower T1 are provided. ing. The tower T1 is composed of a plurality of modules stacked on each other, and the modules provided at the respective heights of the unit blocks E1 to E6 are connected to the wafers W between the transfer mechanisms F1 to F6 of the unit blocks E1 to E6. Can be handed over. These modules include a transfer module TRS provided at the height position of each unit block, a temperature control module CPL for adjusting the temperature of the wafer W, a buffer module for temporarily storing a plurality of wafers W, and a wafer W. It includes a hydrophobic treatment module that makes the surface of the wafer hydrophobic. For the sake of simplicity, the hydrophobization treatment module, the temperature control module, and the buffer module are not shown.

The interface block D3 includes towers T2, T3, and T4 extending vertically across the unit blocks E1 to E6, and is an elevating and lowering transfer mechanism for transferring the wafer W to the towers T2 and T3. To transfer the wafer W between the transfer mechanism 76, the transfer mechanism 77, which is an elevating and lowering transfer mechanism for transferring the wafer W to the tower T2 and the tower T4, and the tower T2 and the exposure apparatus D4. A transport mechanism 78 is provided.

The tower T2 includes a transfer module TRS, a buffer module that stores and retains a plurality of wafers W before exposure processing, a buffer module that stores a plurality of wafers W after exposure processing, and a temperature for adjusting the temperature of the wafer W. Although the control modules and the like are laminated on each other, the buffer module and the temperature control module are not shown here.

The above-mentioned light supply unit 2 is provided above the processing block D2, and the fiber 23 is routed downward so as to be connected to the modules 1A to 1F of the unit blocks E1 to E4 from the light supply unit 2. There is. Further, the above control unit 6 is configured above the processing block D2, and the number of foreign substances for each channel is calculated based on the output signal from the circuit unit 46 of each channel described above, the total number of foreign substances is calculated, and each of them. A calculation unit 60 for calculating the particle size of the foreign matter is provided, and the calculation unit 60 and the modules 1A to 1F are connected by wiring (not shown).

The transfer path of the wafer W in the coating and developing apparatus 1 will be described. The wafer W is conveyed from the carrier C to the transfer module TRS0 of the tower T1 in the processing block D2 by the transfer mechanism 73. The wafer W is distributed and conveyed from the transfer module TRS0 to the unit blocks E1 and E2. For example, when the wafer W is delivered to the unit block E1, among the delivery module TRSs of the tower T1, the transfer module TRS1 (delivery module capable of delivering the wafer W by the transfer mechanism F1) corresponding to the unit block E1. , Wafer W is delivered from the TRS0. When the wafer W is delivered to the unit block E2, the wafer W is delivered from the TRS0 to the delivery module TRS2 corresponding to the unit block E2 among the delivery module TRS of the tower T1. The transfer of these wafers W is performed by the transfer mechanism 75.

The wafers W sorted in this way are conveyed in the order of TRS1 (TRS2) → antireflection film forming module 1C (1D) → heating module → TRS1 (TRS2), and then delivered by the transfer mechanism 75 corresponding to the unit block E3. It is distributed to the module TRS3 and the delivery module TRS4 corresponding to the unit block E4.

The wafer W distributed to TRS3 (TRS4) in this way is TRS3 (TRS4)-> resist coating module 1A (1B)-> heating module-> protective film forming module 1E (1F)-> heating module-> tower T2 transfer module TRS. It is transported in order. After that, the wafer W is carried into the exposure apparatus D4 via the tower T3 by the transfer mechanisms 76 and 78. The exposed wafer W is conveyed between the towers T2 and T4 by the transfer mechanisms 78 and 77, and is conveyed to the transfer modules TRS15 and TRS16 of the tower T2 corresponding to the unit blocks E5 and E6, respectively. After that, it is conveyed to the heating module → the developing module → the heating module → the transfer module TRS5 (TRS6), and then returned to the carrier C via the transfer mechanism 73.

By the way, as shown in FIG. 14, the width L4 of the light receiving elements 45A and 45B may be smaller than the width L6 of the light collecting spot 63. The light collecting spot 63 shown in FIG. 14 is a spot formed on the front surface of the light receiving element 45 and on the same plane as the front surface. That is, even if the mask 61 is not provided, the width of the light receiving region in the light receiving elements 45A and 45B where light can be detected is made smaller than the width L6 of the condensing spot 63, and the scattered light by a normal polymer or solvent is emitted by the light receiving element 45A. , 45B can be suppressed from being irradiated.

The number of light receiving elements 45A corresponding to one light receiving spot 63 is not limited to one, and a plurality of minute light receiving elements 45A are arranged so as to correspond to one light receiving spot 63, and each light receiving element is received. The output signals of the element 45A may be added together for detection. Similarly, a plurality of light receiving elements 45B may be provided for one condensing spot 63. Further, in the above-described example, a plurality of light receiving elements 45 are provided and are configured to be focused on each light receiving element 45, but only one light receiving element 45 is provided so that the light receiving element 45 faces the light receiving element 45. One of the above-mentioned condensing spots 63 may be formed, and the width of the light receiving region of the light receiving element 45 may be smaller than the width of the condensing spot 63.

By the way, the light receiving portion 52 shown in FIG. 15 is provided with the above-mentioned mask 61 so as to overlap in the front-rear direction. The light receiving unit is provided with a moving mechanism 64 for moving each of these masks 61 in the left-right direction. As the mask 61 moves by each moving mechanism 64, the width of the overlapping region of the opening 62 of each mask 61 changes. The two masks 61 form one mask 65, and the opening width L5 of the mask 65 can be changed by moving each mask 61. With such a configuration, the position of each mask 61 in the light receiving portion 52 is adjusted so as to have an opening width L5 corresponding to the chemical solution flowing through the flow path for detecting foreign matter in the flow paths 17A to 17K. As described above, in the mask 65, the size of the opening width L5 is changed according to the chemical solution for which the foreign matter is detected. Therefore, it is possible to detect foreign substances in the chemical solution in each flow path with higher accuracy.

Although an example in which the present invention is applied to a light-scattering light type particle counter using forward scattered light has been described, the present invention detects diffracted light (diffraction fringes) generated by irradiating a foreign substance with laser light. It can be applied to a particle counter in which foreign matter is detected based on a change in the output signal due to the light received by 40 and the diffraction fringe, and it is also applied to a particle counter that detects by a method called the IPSA method. be able to. That is, the application of the present invention is not limited to the particle counter having a specific measurement principle.

By the way, the chemical solution to be detected for foreign matter is not limited to the above-mentioned resist and thinner. For example, the present invention may be applied to the protective film forming modules 1E and 1F and the developing module to detect foreign substances in the chemical solution for forming the protective film and foreign substances in the developing solution. In addition, for example, a chemical solution supply device for forming an insulating film on the wafer W, a cleaning device for supplying a cleaning solution which is a chemical solution for cleaning the wafer W, and an adhesive for adhering a plurality of wafers W to each other are used as a chemical solution. The present invention can be applied to each chemical solution supply device such as a device for supplying the wafer W.

Further, the present invention is not limited to being applied to a chemical solution supply device. For example, the flow path array 16 is provided with a cuvette 15 for gas flow, which is different from the cuvette 15 through which the chemical solution flows. Then, the atmosphere of the region where the wafer W is transported, such as the transport region 74 in the coating and developing apparatus 1, can be supplied to the cuvette 15 for gas flow by a suction pump or the like. The region where the wafer W is conveyed includes a region where the wafer W is processed, such as the resist coating module 1A. Then, as in the case of detecting the foreign matter in the chemical solution, while the gas is flowing through the cuvette for gas passage, an optical path is formed in the cuvette to detect the foreign matter. Therefore, the present invention can not only detect foreign matter contained in the liquid supplied to the wafer W, but also detect foreign matter contained in the surrounding environment. That is, foreign matter contained in the fluid can be detected. The present invention is not limited to the above-described embodiments, and the embodiments can be combined with each other or modified as appropriate.

[Evaluation test]
The evaluation test conducted in connection with the present invention will be described.
・ Evaluation test 1
As the evaluation test 1, in the foreign matter detection unit 4 provided with the mask 61, the laser light is irradiated from the laser light irradiation unit 51 to the light receiving unit 52 via the flow path 17 (17A to 17K), and the light receiving element 45A, The noise level output from 45B was measured. This noise level is the difference between peaks in the voltage waveform. In addition, the flow state of the chemical solution in the flow path 17 during irradiation with the laser beam was changed for each test.

Among the evaluation tests 1, the one in which no liquid flow is formed while the pure water is stored in the flow path 17 during the irradiation of the laser beam is referred to as the evaluation test 1-1. The evaluation test 1-2 is obtained by circulating pure water at 5 mL / min in the flow path 17. Evaluation test 1-3 is obtained by circulating thinner at 5 mL / min in the flow path 17. The evaluation test 1-4 is obtained by circulating a chemical solution for forming an antireflection film in the flow path 17 at 5 mL / min. Further, each of these evaluation tests 1-1 to 1-4 is performed a plurality of times using masks 61 having different opening widths L5, and the opening width L5 is 5 μm, 15 μm, or 53 μm.

The graph of FIG. 16 shows the result of the evaluation test 1, the horizontal axis of the graph shows the opening width (unit: μm) of the mask 61, and the vertical axis of the graph shows the noise level (unit: mVpp). From the graph, in the evaluation tests 1-2 to 1-4 in which the chemical solution flows through the flow path 17, the smaller the opening width, the smaller the noise level, and there is a generally linear relationship between the noise level and the opening width. You can see that. Therefore, it can be seen that the straight line A2 described with reference to FIG. 10 can be obtained. Further, it is considered that the noise level can be lowered and the SN ratio can be increased by appropriately setting the opening width.

・ Evaluation test 2
In the foreign matter detection unit 4, laser light was irradiated from the laser light irradiation unit 51 to the light receiving unit 52 via the flow path 17, and the SN ratio was detected for the signals output from the light receiving elements 45A and 45B. The light receiving unit 52 is also provided with a mask 61 as in the light receiving unit 52 used in the evaluation test 1. Further, while the flow path 17 was being irradiated with the laser beam, the chemical solution flowing through the flow path 17 was changed for each test. In the evaluation test 2-1 the flow path 17 is pure water, in the evaluation test 2-2 thinner is in the flow path 17, and in the evaluation test 2-3, a chemical solution for forming an antireflection film is applied to the flow path 17. In the evaluation test 2-4, each resist was circulated in the flow path 17. However, particles made of PSL (polystyrene latex) having a particle size of 46 nm were mixed as foreign substances in each of the chemical solutions flowing through the flow path 17 in these evaluation tests 2-1 to 2-4. These evaluation tests 2-1 to 2-4 were measured using masks 61 having opening widths L5 of 5 μm, 25 μm, and 53 μm, respectively. The width L6 of the condensing spot 63 in this evaluation test is 53 μm, which is the same as that of the embodiment of the present invention.

The graph of FIG. 17 shows the result of the evaluation test 2, the horizontal axis of the graph shows the opening width L5 (unit: μm) of the mask 61, and the vertical axis of the graph shows the SN ratio (no unit). As shown in the graph, for the evaluation tests 2-1 to 2-4, the SN ratio is larger and the opening width is 25 μm when the opening width is 25 μm and 5 μm than when the opening width is 53 μm. Sometimes the signal-to-noise ratio is particularly high. When the aperture width is 5 μm or 53 μm, the minimum measurable particle size is in the 60 nm range, but when the aperture width is 25 μm, the minimum measurable particle size is in the 40 nm range. Since the SN ratio was increased by setting the aperture width L5 smaller than the width L6 of the condensing spot 63 in this way, the effect of the present invention was shown.

1 Coating and developing device 1A, 1B Resist coating module 15A to 15K Cuvet 17A to 17K Flow path 4 Foreign matter detection unit 40 Light detection unit 50 Detection area 51 Laser light irradiation unit 45A, 45B Light receiving element 6 Control unit 61 Mask 62 Opening

Claims (7)

In a foreign matter detection device that detects foreign matter in the fluid supplied to the object to be processed,
A flow path portion through which a fluid, which is a chemical solution containing a polymer, supplied to the object to be treated flows,
A laser light irradiation unit that irradiates a foreign matter detection region in the flow path portion with a laser beam so that the flow direction of the fluid in the flow path portion and the optical path intersect.
A light receiving element that receives light transmitted through the foreign matter detection region and
A condensing lens provided on the optical path between the flow path portion and the light receiving element for condensing on the light receiving element to form a condensing spot.
A detection unit for detecting foreign matter in the fluid based on the signal output from the light receiving element, and
A mask provided with an opening for forming a light receiving region facing the light collecting spot in the light receiving element.
A moving mechanism for moving the mask and
Assuming that the mask is formed and the direction of the optical path formed by the condenser lens is the front-rear direction, the masks are provided so as to overlap each other in the front-rear direction, and each of the masks has an opening, and the movement mechanism causes the left and right sides of the mask to be relative to each other. A plurality of mask members whose positions are changed to change the width of the overlapping region of each of the openings, which is the width of the light receiving region, are provided.
A foreign matter detection device characterized in that the width of the light receiving region is smaller than the width of the light collecting spot, and the width of the light receiving region is changed according to the type of the chemical solution flowing through the flow path portion. A plurality of the light receiving elements are arranged in the left-right direction, and the light receiving elements are arranged in the left-right direction.
The plurality of mask members each have a plurality of the openings corresponding to the plurality of light receiving elements.
The foreign matter detection device according to claim 1, wherein the width of the light receiving region in each light receiving element is changed at the same time. The foreign matter detection device according to claim 1 or 2, wherein the fluid is a chemical solution for forming a film on the object to be treated. In a graph in which the width of the light receiving region and the amplitude of the signal output from the light receiving element are set on the horizontal axis and the vertical axis, respectively.
Within a range in which the curve representing the characteristics of the signal output from the light receiving element by detecting the foreign matter is larger in amplitude than the straight line representing the characteristics of the noise signal output from the light receiving element, the light receiving region. The foreign matter detecting device according to any one of claims 1 to 3, wherein the width of the foreign object is set. In the graph,
The foreign matter detecting device according to claim 4, wherein the width of the light receiving region is set so that the slope of the tangent line of the curve is aligned with the slope of the straight line. In a foreign matter detecting method for detecting a foreign matter in a fluid which is a chemical solution containing a polymer supplied to an object to be treated.
A step of supplying the fluid to the flow path portion in order to supply the fluid to the object to be processed, and
A step of irradiating a foreign matter detection region in the flow path portion with a laser beam so that the flow direction of the fluid in the flow path portion and the optical path intersect with the laser light irradiation unit.
A step of receiving light transmitted through the foreign matter detection region by a light receiving element,
A step of forming a condensing spot by condensing light on the light receiving element by a condensing lens provided on an optical path between the flow path portion and the light receiving element.
A step of detecting a foreign substance in the fluid by a detection unit based on a signal output from the light receiving element, and
With
A step of forming a light receiving region facing the light collecting spot in the light receiving element by using a mask provided with an opening, and a step of forming the light receiving region.
The process of moving the mask by the moving mechanism and
When the mask is formed and the direction of the optical path formed by the condenser lens is the front-rear direction, the mask members provided so as to overlap each other in the front-rear direction and each having the opening are provided with each other by the moving mechanism. A step of changing the relative positions on the left and right and changing the width of the overlapping region of the openings, which is the width of the light receiving region, and
The width of the light receiving region is smaller than the width of the light collecting spot, and the step of changing the width of the light receiving region according to the type of the chemical solution flowing through the flow path portion.
A method for detecting a foreign substance, which comprises. A storage medium that stores a computer program used in a foreign matter detection device that detects foreign matter in the fluid supplied to the object to be processed.
The computer program is a storage medium in which a group of steps is set up to execute the foreign matter detection method according to claim 6.

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