JP4520975B2 - Coating method and coating apparatus - Google Patents

Description

  The present invention relates to a coating method and a coating apparatus that apply a processing liquid on a substrate to be processed in a spinless manner, and in particular, prevents unwanted contact or rubbing between a nozzle and a substrate due to the presence of foreign matters such as dust. Related to technology.

  In a photolithography process in a manufacturing process of a flat panel display (FPD) such as an LCD, a long resist nozzle having a slit-like discharge port is scanned relative to a substrate to be processed such as a glass substrate. A spinless coating method in which a resist solution is applied on top is often used.

  In this type of spinless coating apparatus, for example, a minute gap (for example, about 100 μm) is set between a substrate horizontally supported on a mounting table and a discharge port at the lower end of the nozzle, and a resist solution is supplied from the nozzle discharge port. The long resist nozzle is moved in a horizontal direction perpendicular to the longitudinal direction of the nozzle while discharging in a strip shape. Then, the resist liquid overflowing on the substrate from the discharge port of the resist nozzle extends flatly from the gap to the rear of the nozzle, and a coating film of the resist liquid is formed on the substrate with a certain thickness (for example, Patent Document 1). .

  In such a spinless system, if a foreign object such as dust or debris that is relatively large (particularly larger than the gap setting value) adheres to the substrate or is sandwiched between the substrate and the mounting table, the resist When the nozzle moves horizontally in the vicinity of the upper surface of the substrate, the lower end of the resist nozzle rubs against the substrate through the foreign matter, or directly rubs against the substrate rising on the foreign matter sandwiched below. If the resist nozzle rubs the upper surface of the substrate in this way, the substrate may be damaged or broken to lose its product value, and a very expensive resist nozzle may be damaged and become unusable.

Therefore, prior to coating scanning, an optical obstacle inspection method has been proposed in which a light beam is used to detect the presence or absence of foreign matter on the substrate or the presence or absence of swell of the substrate (for example, Patent Document 2). In this technique, in front of the scanning direction of the resist nozzle, coating and scanning are performed by arranging the light projecting part and the light receiving part opposite to each other so as to project and receive a light beam crossing the vicinity of the upper surface of the substrate, respectively. In this case, it is moved horizontally together with the resist nozzle. Then, based on the electrical signal output from the light receiving unit that receives the light beam from the light projecting unit at each horizontal movement position, it is determined whether or not the received light amount is below a predetermined threshold value. It is determined that there is an obstacle (foreign matter or swell of the substrate) that hinders the application scanning on the optical path, and the application scanning is stopped.
Japanese Patent Laid-Open No. 10-156255 JP 2006-10642 A

  The conventional optical obstacle inspection method as described above is a technique for accurately detecting the size of the obstacle (foreign matter or substrate rise) and a technique for setting an appropriate comparison reference value (threshold). Since it does not have, it has the subject that the reliability as a monitor function is low.

  That is, conventionally, the height position of the optical path of the light beam is set or adjusted in accordance with the gap setting value, and the light amount of the light beam emitted from the light projecting unit reaches the light receiving unit. Based on this, the presence or absence of obstacles is judged. However, in this method, the sensitivity for detecting an obstacle greatly depends on the beam diameter of the light beam. For this reason, when the beam diameter is large, the detection sensitivity is low, and it may fail to detect foreign matter on the substrate or the rise of the substrate that may interfere with coating scanning. Also, even if the beam diameter is too small, the sensitivity becomes too high and there is no problem with coating scanning (so much that it can be ignored). It may be stopped in vain. Such misjudgment or malfunction is directly linked to a decrease in operating rate and productivity, which is a great practical disadvantage.

  Conventionally, the comparison reference value (threshold value) for the output of the light receiving unit (the amount of received light) is fixed. There is no compensation for the effect of (light reception). In this respect as well, it is difficult to accurately detect only foreign matters on the substrate and those that may interfere with coating scanning among the swells of the substrate.

  The present invention solves the above-described problems of the prior art, and can detect the foreign matter on the substrate and the swell of the substrate that may interfere with the scanning of the coating accurately, thereby applying the spinless coating. An object of the present invention is to provide a coating method and a coating apparatus that improve the safety and productivity of processing.

In order to achieve the above object, the coating method according to the first aspect of the present invention supports a substrate to be processed substantially horizontally at a predetermined height position, and makes a minute from an adjacent position above the substrate. A coating method of coating the processing liquid on the substrate by performing a coating scan in which a nozzle that discharges the processing liquid is moved in a horizontal direction through a gap, and is directed to cross the vicinity of the upper surface of the substrate. A light projecting unit for projecting a light beam having a high property and a light receiving unit having a plurality of light receiving cells arranged in a line or matrix on a light receiving surface for receiving the light beam. Prior to the first step disposed on both sides and the application scanning, the light projecting unit and the light receiving unit are moved in a horizontal direction relative to the substrate from one end to the other end of the substrate. Second step for performing inspection scan And a third step of generating a cell received light amount signal representing the received light amount of the light beam for each light receiving cell by photoelectric conversion of the light receiving unit in a certain cycle during the movement of the inspection scan, A fourth step for obtaining a difference between the current received light amount and the received light amount before a predetermined delay time for each light receiving cell based on the cell received light amount signal; and comparing the received light amount difference with a predetermined reference value. And a sixth step of controlling the operation of the application scanning on the substrate according to the result of the determination.

The coating apparatus according to the first aspect of the present invention includes a support portion that supports a substrate to be processed substantially horizontally at a predetermined height position, and a minute gap above the substrate that is supported by the support portion. A processing liquid supply unit that disposes the nozzles and discharges the processing liquid from the nozzles for coating scanning; and a coating scanning unit that relatively moves the nozzles and the substrate in the horizontal direction for coating scanning; , Disposed on one side of the substrate, projecting a light beam having a high directivity across the upper surface vicinity of the substrate, and disposed on the opposite side of the substrate opposite to the projecting unit, A light receiving unit that receives the light beam by a plurality of light receiving cells arranged in a line or in a matrix and generates a cell light receiving amount signal that represents the light receiving amount of the light beam for each light receiving cell by photoelectric conversion in a certain cycle. And for the application scan An inspection scanning unit that moves the light projecting unit and the light receiving unit in a horizontal direction relative to the substrate from one end to the other end of the substrate, and during the movement of the inspection scan, A received light amount difference calculation unit that calculates a difference between the current received light amount and a received light amount before a predetermined delay time for each light receiving cell based on the cell received light amount signal obtained from the light receiving unit, and the received light amount difference calculation A determination unit that performs determination by comparing a difference in received light amount obtained from the unit with a predetermined reference value, and a control unit that controls the operation of the application scanning according to a determination result obtained from the determination unit.

In the coating method or the coating apparatus according to the first aspect, the difference between the current received light amount and the received light amount before a predetermined delay time is obtained for each of a plurality of light receiving cells provided in a line or matrix in the light receiving unit. From the degree of the difference, the magnitude of the obstacle that obstructs the path of the light beam during the inspection scan is determined. The degree of the size of the obstacle touching the light beam can be determined with high resolution in cell units, and the amount of light received at the current inspection scan position is the relative amount (difference) with respect to the amount of light received before a predetermined delay time in the same scan. Therefore, it is possible to accurately compensate or cancel the influence of the output of the light receiving unit (the amount of received light) due to changes in photoelectric conversion characteristics in the light receiving unit and ambient conditions (such as ambient light and ambient temperature). As a result, it is possible to accurately distinguish between a large obstacle that may cause a problem in coating scanning and a small obstacle that does not interfere at all, and the operation of coating scanning can be appropriately controlled.

  According to a preferred aspect of the present invention, in the fifth step of the coating method or the determination unit of the coating apparatus, whether or not the maximum value of the received light amount difference among all the light receiving cells exceeds a reference value. Method or means for determining, or method for determining whether or not the difference in received light amount exceeds a reference value for each light receiving cell, and determining the range of the corresponding light receiving cell if there is a reference value exceeded Or measures are taken.

In the coating method according to the second aspect of the present invention, the substrate to be processed is supported substantially horizontally at a predetermined height position, and the processing liquid is discharged from a position close to the substrate through a minute gap. A coating method for coating the processing liquid on the substrate by performing a coating scan that relatively moves the nozzle in a horizontal direction, each projecting a highly directional light beam that traverses the vicinity of the upper surface of the substrate. And a first step of disposing the light projecting unit and the light receiving unit on both sides of the substrate so as to receive light, and prior to the application scanning, the light projecting unit and the light receiving unit are placed on the substrate. A second step of performing an inspection scan that is moved relatively horizontally, and a received light amount that represents a received light amount of the light beam by photoelectric conversion of the light receiving unit that receives the light beam during the movement of the inspection scan Generate signal 3 and steps of, on the basis of the received light quantity signal output from the light receiving portion, the present time of the received light quantity and the light receiving amount of the first delay time difference and the present time of the first delay time before the amount of light received A fourth step for obtaining the difference between the received light amount before the longer second delay time as the first and second received light amount differences, and the first and second received light amount differences as a predetermined reference value A fifth step of making a determination by comparison, and a sixth step of controlling the operation of the coating scan on the substrate according to the result of the determination.

In addition, the coating apparatus according to the second aspect of the present invention includes a support unit that supports a substrate to be processed substantially horizontally at a predetermined height position, and a minute gap above the substrate supported by the support unit. A processing liquid supply unit that disposes the nozzles and discharges the processing liquid from the nozzles for coating scanning; and a coating scanning unit that moves the nozzles and the substrate in a relative horizontal direction for coating scanning; , Disposed on one side of the substrate, projecting a light beam having a high directivity across the upper surface vicinity of the substrate, and disposed on the opposite side of the substrate opposite to the projecting unit, A light receiving unit that receives the light beam and generates a received light amount signal that represents a received light amount of the light beam by photoelectric conversion, and the light projecting unit from one end of the substrate toward the other end prior to the application scanning. And the light receiving part relative to the substrate An inspection scan unit that moves in the horizontal direction, during the movement of the inspection scan, the difference and the the amount of light received and the first delay before the received light amount of the present time on the basis of the received light quantity signals obtained from said light receiving portion A received light amount difference calculation unit that calculates a difference between a current received light amount and a received light amount before a second delay time longer than the first delay time as a first received light amount difference and a second received light amount difference; And a determination unit that performs determination by comparing the second received light amount difference with a predetermined reference value, and a control unit that controls the operation of the application scanning according to a determination result obtained from the determination unit.

  In the coating method or the coating apparatus according to the first aspect, the received light amount before the first predetermined time and the second predetermined amount in the same inspection scan are used as the comparison reference value for determining the state of the received light amount at the current inspection scan position. Since the two received light amounts before the time are used, the effects of the light receiving unit output (light receiving amount) due to changes in photoelectric conversion characteristics in the light receiving unit and ambient conditions (ambient light, ambient temperature, etc.) are properly compensated (cancelled) ) And can reliably detect any shape or profile (especially even if the substrate swells gently) if an obstacle that may interfere with coating scanning touches the light beam. be able to.

  According to a preferred aspect of the present invention, in the coating method, the light receiving unit includes a plurality of light receiving cells arranged in a line or matrix on the light receiving surface that receives the light beam. The third step outputs a cell received light amount signal indicating the received light amount of the light beam for each light receiving cell in a fixed cycle, and the fourth step outputs each light receiving cell based on the cell received light amount signal. The first and second received light amount differences are calculated every time, and the fifth step determines whether or not the maximum value of at least one of the first or second received light amount differences exceeds the reference value in all the light receiving cells. Determine whether. Alternatively, as the fifth step, it is determined whether at least one of the first and second received light amount differences exceeds the reference value for each light receiving cell, and if there is an object exceeding the reference value The range of the light receiving cell may be determined. Then, when it is determined in the fifth step that there is an obstacle that is harmful to coating scanning on the optical path of the light beam, a measure for immediately stopping the movement of the nozzle in the sixth step, or immediately Measures are taken to move the nozzle up to a predetermined height position.

  According to a preferred aspect, in the coating apparatus, the light receiving unit receives the light beam from the light projecting unit with a plurality of light receiving cells arranged in a line or matrix, and performs light conversion by photoelectric conversion in a constant cycle. A cell received light amount signal representing the received light amount of the beam for each light receiving cell is generated. In this case, the received light amount difference calculation unit calculates the first and second received light amount difference for each light receiving cell based on the cell received light amount signal from the light receiving unit. The determination unit determines the maximum value of the first and second received light amount differences among all the light receiving cells, and determines whether at least one of the maximum values exceeds the reference value. Alternatively, the determination unit compares the first and second received light amount differences with the reference value for each light receiving cell, and applies when at least one of the first and second received light amount differences exceeds the reference value. The range of the light receiving cell is determined.

  Further, according to a preferred aspect, the light receiving unit arranges a large number of light receiving cells in a line or a matrix in an entire light receiving area of a certain size, and a desired partial area in the entire light receiving area is an effective light receiving area. Can be arbitrarily selected. In this case, the received light amount difference calculation unit performs a received light amount difference calculation process on only the cell received light amount signals obtained from the plurality of light receiving cells included in the effective light receiving area.

  According to a preferred aspect, the position or size of the effective light receiving area in the vertical direction is variably adjusted according to the thickness of the substrate. In this case, of the light beam emitted from the light projecting unit, the lower end of the beam hits one side of the substrate to block the path, and the remaining beam crosses the substrate and is received by the light receiving unit. The lower end of the light receiving area is preferably set at a position lower than the upper surface of the substrate. This effective light receiving area variable adjustment function shifts the effective light receiving area to a higher position when the substrate thickness is relatively large, for example, and shifts the effective light receiving area to a lower position when the substrate thickness is relatively small. The light receiving area can be aligned so as to completely cover the height space of the application gap.

  According to the coating method and the coating apparatus of the present invention, it is possible to accurately detect the foreign matter on the substrate and the swell of the substrate that may interfere with the coating scanning by the configuration and operation as described above. As a result, the safety and productivity of the spinless coating process can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  In FIG. 1, the external appearance structure of the resist coating apparatus in one Embodiment of this invention is shown. FIG. 2 shows the state of the main part during coating scanning and inspection scanning in this resist coating apparatus.

  The resist coating apparatus includes, for example, a stage 10 for horizontally placing and holding a glass substrate G for LCD as a substrate to be processed, and an upper surface (surface to be processed) of the substrate G placed on the stage 10. And a coating processing section 14 for applying a resist solution by a spinless method using a long resist nozzle 12.

  Although not shown, the stage 10 has a large number of suction holes (or suction grooves) on the stage upper surface or the mounting surface, and is configured to suck and hold the substrate G by vacuum force through the suction holes. Yes. Further, in order to transfer the substrate G to and from the transfer arm of the transfer apparatus, a lift pin mechanism for moving a plurality of lift pins up and down (up and down) from the upper surface of the stage is also provided.

  The coating processing unit 14 includes a resist solution supply unit 16 including a resist nozzle 12, a scanning unit 18 that horizontally moves the resist nozzle 12 above the stage 10 in a horizontal direction (X direction) perpendicular to the nozzle longitudinal direction, and a resist nozzle 12 and a nozzle lifting mechanism 20 for adjusting or changing the height position.

  In the resist solution supply unit 16, the resist nozzle 12 has a slit-like discharge port 12a that covers the substrate G from end to end in the longitudinal direction of the nozzle (Y direction), and serves as a resist solution supply source (not shown). It is connected to a resist solution supply pipe 22 that leads to it. The scanning unit 18 includes an inverted U-shaped or gate-shaped support 24 that supports the resist nozzle 12 horizontally, and a scanning drive unit 26 that moves the support 24 in both directions in the X direction. The scanning drive unit 26 can also use a ball screw mechanism, but is preferably composed of a linear servo motor mechanism with little mechanical vibration from the viewpoint of the uniformity of the coating film. The nozzle raising / lowering mechanism 20 is composed of, for example, a ball screw mechanism, and adjusts the height position of the resist nozzle 12 to adjust the distance between the discharge port 12a at the lower end of the nozzle and the substrate G on the stage 10, that is, the coating gap g (see FIG. In addition to setting or adjusting 2) to an arbitrary size, the resist nozzle 12 can also be moved up instantaneously. The illustrated nozzle raising / lowering mechanism 20 directly supports the resist nozzle 12, but it is also possible to attach the resist nozzle 12 to a horizontal support that is slightly larger than the resist nozzle 12 and connect the horizontal support to the elevation drive unit. It is.

  The application processing unit 14 performs application processing under the control of the control unit 28 described later while the substrate G is placed on the stage 10. More specifically, the resist solution supply unit 16 moves the resist nozzle 12 with respect to the substrate G on the stage 10 while the scanning unit 18 moves the resist nozzle 12 horizontally at a constant speed so as to cross the upper side of the stage 10 in the X direction. The resist solution is discharged in a strip shape from the discharge port 12 a of the nozzle 12. Then, the resist solution R overflowing on the substrate G extends flatly to the rear of the nozzle, and a coating film RM of the resist solution R is formed on the substrate G with a certain film thickness corresponding to the coating gap g (FIG. 2). .

  This resist coating apparatus is an obstacle for inspecting in advance whether or not there is an obstacle in scanning of coating in front of the resist nozzle 12 when the resist coating process as described above is performed in the coating processing unit 14. An inspection monitor 30 is provided. As described above, the swell of the substrate G due to foreign matter adhering to the upper surface of the substrate G or foreign matter sandwiched between the substrate G and the stage 10 can be an obstacle of this kind. However, not all foreign matters and the swell of the substrate G are obstacles to the application scanning. As the lower end of the resist nozzle 12 that moves horizontally during coating scanning contacts or rubs against the upper surface of the substrate G, or the variation in the thickness of the resist coating film exceeds an allowable range, the larger foreign matter and the swell of the substrate interfere with the coating scanning. When such a large obstacle is detected, the application scanning should be stopped immediately from the viewpoint of safety. However, other small foreign matters and the rise of the substrate may be ignored in the application scanning, and it is not desirable from the viewpoint of production efficiency to stop the application scanning for such a small obstacle. As will be described below, the obstacle inspection monitor 30 in this embodiment has a function of accurately detecting only foreign substances on the substrate and swells of the substrate that may interfere with application scanning. Yes.

In FIG. 1, an obstacle inspection monitor 30 is a light beam having a high directivity (for example, such that it crosses the vicinity of the upper surface of the substrate G placed on the stage 10 substantially horizontally in the Y direction at a predetermined height position). A light projecting unit 32 that emits or projects a laser beam LB; and a light receiving unit 34 that is disposed at a position facing the light projecting unit 32 with the substrate G on the stage 10 sandwiched in the Y direction. As shown in the figure, the light projecting unit 32 and the light receiving unit 34 are respectively attached to a pair of horizontal support arms 36 and 38 projecting forward from the left and right side surfaces of the support 24 in the scanning direction. In addition, the light beam LB is projected and received substantially horizontally at a position ahead by a certain distance (for example, 100 mm to 200 mm).

  FIG. 3 shows the positional relationship between the substrate G on the stage 10, the light projecting unit 32, the light receiving unit 34, and the optical path of the light beam LB. The light projecting unit 32 may be a single LD (semiconductor laser), but is preferably composed of a one-dimensional LD array or a two-dimensional LD array in which a number of LDs are arranged in a horizontal row or a vertical and horizontal matrix. 35 (FIG. 9) receives a drive current to emit light, and emits a light beam LB having a beam diameter or beam size (for example, 2 mm × 2 mm) much larger than the coating gap g (for example, 100 μm). At this time, the lower end portion of the light beam LB emitted from the light projecting unit 32 is cut off at one side surface of the substrate G, and only the beam portion that propagates horizontally in a space higher than the upper surface of the substrate G is the light receiving unit 34. The height position of the beam optical path may be set or adjusted so as to reach the light receiving surface 34a.

  4 and 5 show the arrangement of the light receiving cells provided on the light receiving surface 34a of the light receiving unit 34. FIG. The light receiving unit 34 is formed of a two-dimensional CCD (Charge-Coupled Device) in which a large number of light receiving cells J are arranged in a vertical and horizontal matrix in an entire light receiving area of a certain size (for example, 3 mm in length × 3 mm in width). The light received for each light receiving cell J is photoelectrically converted with a period of θ to generate a signal charge or an analog cell light reception signal indicating the light reception amount, and the cell light reception signal is time-sequentially determined by a predetermined transfer method. It is designed to output serially. However, in the effective light receiving area selection circuit 46 (FIG. 7), which will be described later, only the cell light reception amount signal obtained from the light receiving cell J in the desired partial area (effective light receiving area) A designated in all the light receiving areas. Can be selected.

  With this effective light receiving area selection function, the position (particularly the vertical position) and / or size (range) of the effective light receiving area A can be arbitrarily variably adjusted. For example, when the thickness d of the substrate G is relatively large, the effective light receiving area A indicated by the bold frame is shifted to a higher position (FIG. 4), and when the thickness d of the substrate G is relatively small, the effective light receiving area A is lowered. By shifting to the position (FIG. 5), the effective light receiving area A can always be aligned so as to completely cover the height space of the coating gap g. Further, also in the optical axis alignment between the light projecting unit 32 and the light receiving unit 34, mechanical position adjustment of the light projecting unit 32 or the light receiving unit 34 becomes unnecessary by using this effective light receiving area selection function.

  One of the simplest basic forms of the effective light receiving area A is a case where a plurality of (n) light receiving cells J1 to Jn for one horizontal row or one row are formed as shown in FIG. As an example, when the coating gap g is 100 μm, the size of each light receiving cell Ji is selected to be 300 μm in length × 300 μm in width, and the lowermost 50 μm portion may be set lower than the upper surface of the substrate G. Although not shown in the drawing, the effective light receiving area A can be configured by a vertical line of light receiving cells J1 to Jn.

  FIG. 7 shows a configuration of the cell light reception amount signal processing circuit 40 provided on the light receiving unit 34 side in the obstacle inspection monitor 30. In this cell received light amount signal processing circuit 40, the cell received light amount signal for the entire light receiving area read out from the light receiving unit 34 every constant cycle θ is removed from the noise component by the low-pass filter (LPF) 42 and then analog / digital. The A / D conversion is received by the converter 44 and input to the effective light receiving area selection circuit 46 in the form of a digital signal.

  The effective light receiving area selection circuit 46 temporarily stores in the buffer memory the cell received light amount signals for all the light receiving areas read out by the light receiving unit 34 at each cycle θ, and then sets the position and range of the effective light receiving area A that has been set. Only the cell received light amount signals [j to jn] read from the light receiving cells J1 to Jn in the effective light receiving area A are read from the buffer memory in time series.

  The cell received light amount signals [j1 to jn] of each cycle read from the effective light receiving area selection circuit 46 are input to the first delay circuit 50 and to the obstacle presence / absence determination circuit 54. The first delay circuit 50 delays and outputs the received cell received light amount signal [j1 to jn] of each cycle by the first set delay time T1. The cell received light amount signals [j1 ′ to jn ′] for each cycle output from the first delay circuit 50 are input to the second delay circuit 52 at the subsequent stage and to the obstacle presence / absence determination circuit 54. The second delay circuit 52 delays and outputs the cell received light amount signal [j1 ′ to jn ′] of each cycle input from the first delay circuit 50 by a second set delay time ΔT (ΔT = T2−T1). The cell received light amount signal [j1 "to jn"] of each cycle output from the second delay circuit 52 is input to the obstacle presence / absence determination circuit 54.

  In this manner, the obstacle presence / absence determination circuit 54 receives the current cell received light amount signal [j1 to jn] from the effective light receiving area selecting circuit 46 and the cell received light amount signal before the first set delay time T1 from the first delay circuit 50. [J1 ′ to jn ′] and cell received light amount signals [j1 ″ to jn ″] before the second set delay time T2 from the second delay circuit 52 are input simultaneously. The obstacle presence / absence determination circuit 54 is based on these three sets of cell received light amount signals [j1 to jn], [j1 ′ to jJn ′] and [j1 ″ to jn ″] obtained with a predetermined time difference from the effective light receiving area A. Thus, it is determined whether or not there is a substantial obstacle on the optical path of the light beam LB at the current inspection scanning position that causes an obstacle in coating scanning.

  The setting unit 48 sets the position and range of the effective light receiving area A, the first set delay time T1, and the second set delay time T2 to the effective light receiving area selection circuit 46, the first delay circuit 50, and the second delay circuit 52. Are given to the obstacle presence / absence judgment circuit 54.

  FIG. 8 shows a configuration example of the obstacle presence / absence determination circuit 54. Three sets of received cell light amount signals simultaneously input, that is, the current received cell light amount signal [j1 to jn], the received cell light amount signal [j1 ′ to jn ′] before the first set delay time T1, and the second set delay time. The cell received light amount signals [j1 "to jn"] before T2 are individually stored in the three buffer memories 60, 62, and 64, respectively.

  The first difference calculation circuit 66 receives, for each light receiving cell, a difference between the current cell light reception amount signal [j1 to jn] and the cell light reception amount signal [j1 ′ to jn ′] before the first set delay time T1, that is, light reception. Calculate the amount difference. Next, the first maximum value determination circuit 68 compares the n received light amount difference (j1′−j1) to (jn′−jn) to determine the maximum value Max (ji′−ji) therein. To do.

  On the other hand, the second difference calculation circuit 70 calculates the difference between the current cell received light amount signal [j1 to jn] and the cell received light amount signal [j1 "to jn"] before the second set delay time T2 for each light receiving cell. Is calculated. Next, the second maximum value determination circuit 72 compares the n received light amount differences (j1 "-j1) to (jn" -jn) to determine the maximum value Max (ji "-ji) among them. To do.

  The comparison determination circuit 74 determines whether or not the maximum value Max (ji′−ji) of the received light amount difference determined by the first maximum value determination circuit 68 exceeds the first comparison reference value K1 by the magnitude comparison. 2 It is determined whether or not the maximum value Max (ji "-ji) of the difference in received light amount determined by the maximum value determination circuit 72 exceeds the second comparison reference value K2. The first and second comparison reference values K1 and K2 may be the same value or different values, and both of the received light amount difference maximum values Max (ji′−ji) and Max (ji ″ −ji) must exceed the comparison reference values K1 and K2. If it is “normal”, that is, it is determined that there is no substantial obstacle on the optical path of the light beam LB at the current inspection scanning position that would impede the application scanning. However, when one or both of the maximum difference between received light amounts Max (ji′−ji) and Max (ji ″ −ji) exceed the comparison reference values K1 and K2, “abnormal”, that is, the current inspection scanning position. It is determined that there is an obstacle on the optical path of the light beam LB that may interfere with coating scanning. In this way, a determination result or a monitor result is obtained from the determination unit 74 every constant cycle θ. The data of the monitoring result is given to the control unit 28 (FIG. 9).

  FIG. 9 shows the main configuration of the control system in the resist coating apparatus of this embodiment. The control unit 28 includes one or a plurality of microcomputers and emits light from each unit in the unit, in particular, the resist solution supply unit 16 of the coating processing unit 14, the scanning unit 18, the nozzle lifting mechanism 20, and the obstacle inspection monitor 30. The individual operation and overall operation (sequence) of the drive circuit 35 and the cell light reception amount signal processing circuit 40 are controlled. In particular, the control unit 28 has a program memory for storing a program (software) for executing all the controls related to the coating process and obstacle inspection and all the controls related to various additional functions. A control unit (CPU) reads and executes a required program sequentially from the program memory. Various storage media such as a hard disk, an optical disk, and a flash memory can be used for program storage management.

  Next, the operation of the obstacle inspection monitor 30 in the resist coating apparatus of this embodiment will be described. As shown in FIG. 2, the inspection scan on the substrate G on the stage 10 is performed along with the application scan in the application processing unit 14 and in an appropriate moving distance (100 mm to 200 mm). ) Only precedes (forward). In this case, the light projecting unit 32 and the light receiving unit 34 move horizontally in the X direction at a constant speed V together with the resist nozzle 12, and the light receiving unit 34 and the cell received light amount signal processing circuit at every constant cycle θ during the movement of the inspection scan. In 40, the cell received light amount signal [j1 to jn] is read from the effective light receiving area A as described above, the comparison determination process, and the output of the monitoring result are performed.

For example, when the effective light-receiving area A has a horizontal width of 3 mm and the scanning speed V is 100 mm / sec, if the inspection cycle θ is set to 30 msec, a pitch equal to the horizontal width of the effective light-receiving area A as shown in FIG. Inspection scan is monitored at θ ₁ , θ ₂ . When the inspection cycle θ is set to 15 msec, the inspection scanning is monitored at a pitch (θ ₁ , θ ₂ ...) Of ½ of the lateral width of the effective light receiving area A as shown in FIG. In this case, assuming that the number of cells in the effective light receiving area A is, for example, 10 [J1 to J10], the same place inspected by the first half [J1 to J5] in a certain cycle θ _i is the next cycle θ _{i + 1} . The latter half [J6 to J10] can be inspected again.

  12 and 13 show some typical examples of foreign objects or obstacles detected by the obstacle inspection monitor 30. FIG.

  FIG. 12A shows a case where a foreign substance Q1 considerably lower (for example, 20 to 60 μm) than the height level (100 μm) of the coating gap g is attached to the upper surface of the substrate G. In this case, when the effective light receiving area A of the light receiving unit 34 reaches the place where the foreign matter Q1 is present, the amount of light received by one or several light receiving cells Ji on which the foreign matter Q1 is projected in the current effective light receiving area A. Is somewhat reduced, so that the amount of light received by the light receiving cell Ji in the effective light receiving area A ′ before the first set delay time T1 (moving distance behind S1) and in time. A significant difference appears between the light receiving amount of the light receiving cell Ji in the effective light receiving area A ′ before the second set delay time T2 (backward of S2 in terms of movement distance), and these are the maximum values Max of the received light amount difference. (Ji′−ji), Max (ji ″ −ji) are output from the first and second maximum value determination circuits 68 and 72. However, in the comparison / determination circuit 74, the maximum value Max (ji of both received light amounts) '-Ji) Max (ji "- ji) for none of not exceeding the reference value K1, K2, the monitoring result of" normal "is output. Therefore, even if the foreign object Q1 is detected by the obstacle inspection monitor 30, the control unit 28 causes the coating processing unit 14 to continue the coating process.

  When the effective light receiving area A is 3 mm wide, the scanning speed V is 100 mm / sec, and the inspection cycle θ is 15 msec, the first set delay time T1 and the second set delay time T2 are set to 10 msec and 100 msec, for example. Good.

  FIG. 12B shows a case where foreign matter Q2 equal to or higher than the height level of the coating gap g (for example, 100 to 200 μm) adheres to the upper surface of the substrate G. In this case, when the effective light receiving area A of the light receiving unit 34 reaches the place where the foreign object Q1 is present, the light reception of one or several light receiving cells Ji on which the foreign object Q2 is projected in the current effective light receiving area A. The amount of light received decreases in the effective light receiving area A ′ before the first set delay time T1 and the light received in the effective light receiving area A ′ before the second set delay time T2. A considerably large difference appears between the cell light reception amount of the cell Ji and the first and second maximum value determination circuits as maximum values Max (ji′−ji) and Max (ji ″ −ji) of the light reception amount difference. 68 and 72. In the comparison / determination circuit 74, the maximum values Max (ji'-ji) and Max (ji "-ji) of both received light amount differences exceed the reference values K1 and K2. When The “abnormal” monitoring result is output. As described above, when the “abnormal” monitoring result is output from the obstacle inspection monitor 30, the control unit 28 immediately causes the coating processing unit 14 to stop the coating process. That is, the scanning unit 18 stops the movement of the resist nozzle 12 and the resist solution supply unit 16 stops the discharge of the resist solution. Further, if necessary, instead of stopping the scanning movement of the resist nozzle 12, the resist nozzle 12 can be moved up by the nozzle lifting mechanism 20 to pass far above the foreign matter Q2.

  FIG. 13A shows a case where a large granular foreign material Q3 is sandwiched between the substrate G and the stage 10 and the substrate G protrudes in a protruding manner higher than the height level of the coating gap g. Also in this case, as in the case of FIG. 12B, when the inspection scan has reached this substrate swell H3, one or several of the substrate swell H3 projected in the current effective light receiving area A is projected. The light receiving amount of the light receiving cell Ji greatly decreases, and the effective light receiving area A between the light receiving amount of the light receiving cell Ji in the effective light receiving area A ′ before the first set delay time T1 and before the second set delay time T2. A considerable difference appears between the light reception cell Ji and the light reception amount of the light reception cell Ji, and the monitoring result “abnormal” is output from the cell light reception amount signal processing circuit 40. Then, in response to this monitor result output, the control unit 28 immediately causes the coating processing unit 14 to stop the coating process.

  FIG. 13B shows a case where a large and flat foreign matter Q4 is sandwiched between the substrate G and the stage 10 and the substrate G is gently raised above the height level of the coating gap g. In this case, when the inspection scan reaches the gentle substrate swell H4, the amount of light received by each light receiving cell Ji in the effective light receiving area A at this time decreases little by little. Therefore, cell light reception of the light receiving cell Ji in the effective light receiving area A ′ before the first set delay time T1 and in the effective light receiving area A ′ before the second set delay time T2 Only a small difference appears between the quantities. In particular, since the effective light receiving area A ′ before the first set delay time T1 is not so far behind the current effective light receiving area A by 10 mm, the light receiving amount of each light receiving cell Ji gradually increases in the current effective light receiving area A. Even if it greatly decreases, the difference from the received light amount of each light receiving cell Ji in the effective light receiving area A ′ before the first set delay time T1 increases only slightly. However, since the effective light receiving area A ′ before the second set delay time T2 is 100 mm behind the current effective light receiving area A, the amount of light received by each light receiving cell Ji gradually decreases in the current effective light receiving area A. A large difference (open) appears between the light receiving amount of each light receiving cell Ji in the effective light receiving area A ′ before the second set delay time T2, and the light receiving amount difference output from the second maximum value determining circuit 72 The maximum value Max (ji "-ji) exceeds the reference value K2, and the monitoring result of" abnormal "is output from the comparison determination circuit 74. In response to this monitor result output, the control unit 28 immediately causes the coating processing unit 14 to stop the coating process.

  Thus, normally, the received light amount of each light receiving cell Ji in the effective light receiving area A in the current time and the received light amount of each light receiving cell Ji in the effective light receiving area A ′ considerably before (before the second set delay time T2) From the magnitude of the difference, it is possible to almost certainly determine the presence or absence of a substantial obstacle at the current inspection scanning position. However, if there is an obstacle that does not exceed the threshold at the inspection position of the effective light receiving area A "before the second set delay time T2, the height level of the application gap g is slightly exceeded at the current inspection position. Even if there is an obstacle, this may be overlooked, in which case the amount of light received by each light receiving cell Ji in the current effective light receiving area A and the effective light receiving area A ′ before the first set delay time T1. The difference from the amount of light received by each light receiving cell Ji makes sense as insurance or backup, and the maximum value Max (ji′−ji) among them exceeds the reference value K1, and an “abnormal” monitoring result can be obtained. it can.

  As described above, the obstacle inspection monitor 30 in this embodiment is a beam that can cover the light beam LB used for the obstacle inspection scan with sufficient margin from the upper surface of the substrate G to the height level of the coating gap g. The effective light receiving area A is set at an arbitrary position or height on the light receiving surface 34a of the light receiving unit 34, which is set to the size and the beam height position, and a large number of light receiving cells are arranged in a horizontal or vertical and horizontal matrix. Only cell received light amount signals obtained from a plurality of light receiving cells included in the effective light receiving area A are selectively read out. Then, based on the selectively received cell received light amount signal, the current received light amount, the received light amount before the first set delay time T1, and the second set delay time T2 before for each light receiving cell in the effective light receiving area. When the difference between the received light amount is calculated and at least one of the maximum values Max (ji′−ji) and Max (ji ″ −ji) of both received light amount exceeds the reference values K1 and K2, A determination result that there is an obstacle that hinders the application scan at the position of the inspection scan, that is, a monitor result of “abnormal” is output.

  According to the monitoring method of such an embodiment, the range of the effective light receiving area A in which the change in the amount of received light for each light receiving cell is much smaller than the size of the coating gap g is much larger than the size of the coating gap g. Because it is inspected over time, the size of any obstacle can be accurately detected with high resolution, thereby accurately distinguishing between large obstacles that may cause problems in application scanning and small obstacles that do not interfere at all. It is possible to prevent the former obstacle from colliding or rubbing between the resist nozzle 12 and the substrate G, and the latter obstacle is wasteful (nonsense). A stop can be avoided appropriately.

  Furthermore, since the received light amount before a predetermined time in the same inspection scan is used as a comparison reference value for determining the state of the received light amount at the current inspection scanning position, changes in photoelectric conversion characteristics in the light receiving unit and ambient conditions (ambient light, It is possible to accurately compensate (cancel) the influence of the output (light reception amount) of the light receiving unit due to the ambient temperature or the like. Moreover, since the received light amount a little before (before the first set time T1) and the received light amount a little before (before the second set time T2) are used as the comparison reference values, the accuracy or reliability of the monitor determination is further improved. Can be made.

  The preferred embodiment has been described above, but various modifications can be made within the scope of the technical idea of the present invention.

  For example, FIG. 14 shows another configuration example of the obstacle presence / absence determination circuit 54 included in the light receiving cell signal processing circuit 40 of the obstacle inspection monitor 30. In this configuration example, a first comparison / determination circuit 76, a second comparison / determination circuit 78, and an obstacle size determination circuit 80 are provided downstream of the first difference calculation circuit 66 and the second difference calculation circuit 70, respectively.

  The first comparison / determination circuit 76 outputs the current cell received light amount signal [j1 to jn] for each light receiving cell output from the first difference calculation circuit 66 and the cell received light amount signal [j1 before the first set delay time T1. '~ Jn'] is input, and if there is a size comparison that exceeds the first comparison reference value K1, the corresponding light receiving cell is determined, and the identification information of the light receiving cell is obtained. The obstacle size determination circuit 80 is notified. The second comparison / judgment circuit 78 outputs the current cell received light amount signal [j1 to jn] output from the second difference calculating circuit 70 and the cell received light amount signal [j1 before the second set delay time T2]. "~ Jn"] is input, and if there is a size comparison that exceeds the second comparison reference value K2, the corresponding light receiving cell is determined, and the identification information of the light receiving cell is obtained. The obstacle size determination circuit 80 is notified.

  The obstacle size determination circuit 80 is a range or region of the corresponding light receiving cell in which the received light amount difference value exceeds the comparison reference value K from the corresponding light receiving cell identification information received from the first comparison determination circuit 76 and the second comparison determination circuit 78. Is compared with a predetermined comparison reference value (region size) M, and a monitoring result of “normal” is output if the comparison reference value M is not exceeded, and “abnormal” is output if the comparison reference value M is exceeded.

  In this configuration example, when a large number of light receiving cells are arranged in an effective light receiving area A in a vertical and horizontal matrix, the size (particularly the size in the height direction) or shape of an obstacle can be detected more accurately. Can do.

  Further, the obstacle inspection monitor 30 in the above embodiment should be regarded as dangerous from the viewpoint of whether or not the lower end of the resist nozzle 12 rubs against or contacts the upper surface of the substrate G with respect to the obstacle detected during the application scanning. Although a distinction is made between those that can be ignored, it is also possible to distinguish between those that should be considered dangerous and those that can be ignored from the viewpoint of the film thickness characteristics (particularly the film thickness uniformity) of the resist coating film.

  Further, as another modification, although there is a certain decrease in the monitor determination accuracy, a comparison reference value for determining the state of the amount of received light at the current inspection scan position is two previous set times (T1, T2). It is possible to use only the received light amount before one set time instead of the received light amount. It is also possible to execute the inspection scan separately from the application scan. The present invention also applies to a coating method in which the substrate or the stage side is horizontally moved while the resist nozzle is fixed in the inspection scanning and / or coating scanning, and a coating method in which the substrate is floated and supported on the stage by a gas pressure. Is possible.

  Although the above-described embodiment relates to a resist coating apparatus for LCD, the present invention can be applied to any application that supplies a coating liquid onto a substrate to be processed. As the coating solution in the present invention, in addition to the resist solution, liquids such as an interlayer insulating material, a dielectric material, and a wiring material can be used. The substrate to be treated in the present invention is not limited to a glass substrate for LCD, but may be other flat panel display substrates, semiconductor wafers, CD substrates, photomasks, printed substrates and the like.

It is a perspective view which shows the external appearance structure of the resist coating apparatus in one Embodiment of this invention. It is a partial side view which shows the mode of the principal part in the application | coating scanning and test | inspection scan in the resist coating device of embodiment. It is a side view which shows the relationship between the board | substrate on a stage, a light projection part, a light-receiving part, and a light beam optical path in embodiment. It is a schematic front view which shows the selection example of the arrangement structure of the light reception cell provided in the light-receiving surface of a light-receiving part and effective light-receiving area in embodiment. It is a schematic front view which shows another example of arrangement | positioning structure of the light reception cell in embodiment, and another selection example of an effective light reception area. It is a schematic front view which shows the simplest basic form of the effective light-receiving area in embodiment. It is a block diagram which shows the structure of the cell received light amount signal processing circuit in embodiment. It is a block diagram which shows the structural example of the obstruction presence / absence determination circuit in the cell received light amount signal processing circuit of the embodiment. It is a block diagram which shows the structure of the main control systems in the resist coating device of embodiment. It is a figure which shows an example of the monitoring pitch in the test | inspection scan of embodiment. It is a figure which shows another example of the monitoring pitch in the test | inspection scan of embodiment. It is a side view which shows typically an example of the obstruction inspection in embodiment. It is a side view which shows typically an example of the obstruction inspection in embodiment. It is a block diagram which shows another structural example of the obstruction presence / absence determination circuit in the cell received light amount signal processing circuit of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Table 12 Resist nozzle 14 Application | coating process part 16 Resist liquid supply part 18 Scan part 20 Nozzle raising / lowering mechanism 30 Nozzle obstruction monitor 32 Light projection part 34 Light reception part 34a Light reception surface 40 Cell received light amount signal processing circuit

Claims (20)

Application scanning in which a substrate to be processed is supported substantially horizontally at a predetermined height position, and a nozzle for discharging a processing liquid is moved in a relatively horizontal direction through a minute gap from a position close to the substrate. And applying the treatment liquid onto the substrate,
A light projecting unit that projects a light beam with high directivity that traverses the vicinity of the upper surface of the substrate, and a light receiving unit that has a plurality of light receiving cells arranged in a row or in a matrix on a light receiving surface for receiving the light beam; A first step in which the two are oppositely disposed on both sides of the substrate;
A second step of performing an inspection scan for moving the light projecting unit and the light receiving unit in a horizontal direction relative to the substrate from one end to the other end of the substrate prior to the application scanning;
A third step of generating a cell received light amount signal representing the received light amount of the light beam for each light receiving cell by photoelectric conversion of the light receiving unit in a certain cycle during the movement of the inspection scan;
A fourth step of obtaining a difference between the current received light amount and the received light amount before a predetermined delay time for each light receiving cell based on the cell received light amount signal;
A fifth step of making a determination by comparing the difference in received light amount with a predetermined reference value;
And a sixth step of controlling an operation of the application scanning on the substrate according to the result of the determination.   The coating method according to claim 1, wherein the fifth step determines whether or not a maximum value of the difference in received light amount exceeds the reference value in all light receiving cells.   In the fifth step, it is determined whether or not the difference in received light amount exceeds the reference value for each light receiving cell, and if there is a reference value exceeding the reference value, the range of the corresponding light receiving cell is determined. The coating method according to claim 1 for determining. Application scanning in which a substrate to be processed is supported substantially horizontally at a predetermined height position, and a nozzle for discharging a processing liquid is moved relatively horizontally through a minute gap from a position close to the substrate. And applying the treatment liquid onto the substrate,
A first step of arranging a light projecting portion and a light receiving portion on opposite sides of the substrate so as to project and receive a highly directional light beam crossing the vicinity of the upper surface of the substrate, respectively;
A second step of performing an inspection scan for moving the light projecting unit and the light receiving unit in a horizontal direction relative to the substrate prior to the application scan;
A third step of generating a received light amount signal representing a received light amount of the light beam by photoelectric conversion of the light receiving unit that receives the light beam during the movement of the inspection scan;
Based on the received light amount signal output from the light receiving unit, the difference between the current received light amount and the received light amount before the first delay time and the second received light amount and the second delay time longer than the first delay time. A fourth step for obtaining a difference from the received light amount before the delay time as first and second received light amount differences,
A fifth step of making a determination by comparing the difference between the first and second received light amounts with a predetermined reference value;
And a sixth step of controlling an operation of the application scanning on the substrate according to the result of the determination. The light receiving unit has a plurality of light receiving cells arranged in a line or matrix on a light receiving surface that receives the light beam,
The third step outputs a cell received light amount signal representing the received light amount of the light beam for each light receiving cell in a fixed cycle,
The fourth step calculates the first and second received light amount difference for each light receiving cell based on the cell received light amount signal,
5. The coating method according to claim 4, wherein the fifth step determines whether or not a maximum value of at least one of the first or second received light amount difference among all the light receiving cells exceeds the reference value. . The light receiving unit has a plurality of light receiving cells arranged in a line or matrix on a light receiving surface that receives the light beam,
The third step outputs a cell received light amount signal representing the received light amount of the light beam for each light receiving cell in a fixed cycle,
The fourth step calculates the first and second received light amount difference for each light receiving cell based on the cell received light amount signal,
In the fifth step, it is determined whether at least one of the first and second received light amount differences exceeds the reference value for each light receiving cell. 5. The coating method according to claim 4, wherein the range of the corresponding light receiving cell is determined.   The said light projection part and the said light-receiving part are arrange | positioned ahead of the said nozzle in the said scanning direction, and are moved relatively with respect to the said board | substrate with the said nozzle. Application method.   If it is determined in the fifth step that there is an obstacle on the optical path of the light beam that may interfere with coating scanning, the nozzle immediately stops moving in the sixth step. The coating method according to claim 7.   If it is determined in the fifth step that there is an obstacle on the optical path of the light beam that may interfere with coating scanning, the nozzle is immediately moved to a predetermined height in the sixth step. The coating method according to claim 7, wherein the coating is moved up to a vertical position. A support part for supporting the substrate to be processed substantially horizontally at a predetermined height position;
A processing liquid supply unit that disposes a nozzle above the substrate supported by the support unit via a minute gap and discharges the processing liquid from the nozzle for application scanning;
An application scanning unit that relatively moves the nozzle and the substrate in the horizontal direction for application scanning;
A light projecting unit disposed on one side of the substrate and projecting a light beam having a high directivity across the vicinity of the upper surface of the substrate;
The light beam is received by a plurality of light receiving cells arranged opposite to the light projecting unit and opposite to the substrate, and arranged in a row or in a matrix, and received by the photoelectric conversion in a constant cycle. A light receiving unit for generating a cell light receiving amount signal representing the amount for each light receiving cell;
Prior to the coating scan, an inspection scanning unit that moves the light projecting unit and the light receiving unit in a horizontal direction relative to the substrate from one end to the other end of the substrate;
Received light amount difference for calculating the difference between the current received light amount and the received light amount before a predetermined delay time for each light receiving cell based on the cell received light amount signal obtained from the light receiving unit during the movement of the inspection scan An arithmetic unit;
A determination unit that performs determination by comparing the received light amount difference obtained from the received light amount difference calculation unit with a predetermined reference value;
And a control unit that controls the operation of the application scanning according to a determination result obtained from the determination unit.   The application according to claim 10, wherein the determination unit determines the maximum value of the difference in received light amount among all the light receiving cells, and determines whether the maximum value of the difference in received light amount exceeds the reference value. apparatus.   The said determination part compares the said light reception amount difference for each light reception cell with the said reference value, and if there exists what exceeds the said reference value, the range of the corresponding light reception cell will be determined. Coating device. The light receiving unit arranges a large number of light receiving cells in a row or matrix in a whole light receiving area of a certain size, and an arbitrary partial area forming a part of the whole light receiving area can be arbitrarily selected as an effective light receiving area. ,
The said light reception amount difference calculating part uses only the cell light reception amount signal obtained from the some light reception cell contained in the said effective light reception area for the calculation process of the said light reception amount difference. Coating device. A support part for supporting the substrate to be processed substantially horizontally at a predetermined height position;
A processing liquid supply unit that disposes a nozzle above the substrate supported by the support unit via a minute gap and discharges the processing liquid from the nozzle for application scanning;
A coating scanning unit that moves the nozzle and the substrate in a relative horizontal direction for coating scanning;
A light projecting unit disposed on one side of the substrate and projecting a light beam having a high directivity across the vicinity of the upper surface of the substrate;
A light receiving unit disposed opposite to the substrate opposite to the light projecting unit, receiving the light beam and generating a received light amount signal representing the received light amount of the light beam by photoelectric conversion;
Prior to the coating scan, an inspection scanning unit that moves the light projecting unit and the light receiving unit in a horizontal direction relative to the substrate from one end to the other end of the substrate;
During the movement of the inspection scan, based on the received light amount signal obtained from the light receiving unit, the difference between the current received light amount and the received light amount before the first delay time, and the current received light amount and the first delay. A received light amount difference calculating unit that calculates a difference from the received light amount before the second delay time longer than the time as a first received light amount difference and a second received light amount difference;
A determination unit configured to perform determination by comparing the first and second received light amount differences with a predetermined reference value;
And a control unit that controls the operation of the application scanning according to a determination result obtained from the determination unit. The light receiving unit receives the light beam by a plurality of light receiving cells arranged in a line or in a matrix, and receives a light receiving amount signal of the light beam for each light receiving cell by photoelectric conversion in a constant cycle. Produces
The received light amount difference calculation unit calculates the first and second received light amount difference for each light receiving cell based on the cell received light amount signal,
The determination unit determines a maximum value of the first and second received light amount differences among all the light receiving cells, and determines whether at least one maximum value exceeds the reference value. The coating apparatus as described in. The light receiving unit receives the light beam by a plurality of light receiving cells arranged in a line or in a matrix, and a cell light receiving amount signal representing the light receiving amount of the light beam for each light receiving cell by photoelectric conversion in a constant cycle Produces
The received light amount difference calculation unit calculates the first and second received light amount difference for each light receiving cell based on the cell received light amount signal,
The determination unit compares the first and second received light amount differences with the reference value for each light receiving cell, and at least one of the first and second received light amount differences exceeds the reference value. The coating apparatus according to claim 15, wherein in the case, the range of the corresponding light receiving cell is determined.   The inspection scanning unit arranges the light projecting unit and the light receiving unit in front of the nozzle in the scanning direction and moves the light projecting unit and the light receiving unit relative to the substrate together with the nozzle. A coating apparatus according to claim 1. The light receiving unit arranges a large number of light receiving cells in a row or matrix in a whole light receiving area of a certain size, and allows a desired partial area in the whole light receiving area to be arbitrarily selected as an effective light receiving area,
The light reception amount difference calculation unit uses only cell light reception amount signals obtained from a plurality of light reception cells included in the effective light reception area in the calculation process of the light reception amount difference. Coating device.   The coating apparatus according to claim 13 or 18, wherein the position or size of the effective light receiving area in the vertical direction is variably adjusted according to the thickness of the substrate.   Of the light beam emitted from the light projecting unit, the lower end of the beam hits one side surface of the substrate to block the path, and the remaining beam portion traverses the substrate and is received by the light receiving unit. The coating apparatus according to claim 19, wherein the lower end portion of the effective light receiving area is set at a position lower than the upper surface of the substrate.

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