JP4295175B2 - Coating film forming apparatus and coating film forming method - Google Patents

Description

  The present invention relates to a coating film forming apparatus and a coating film forming method for forming a film by applying a predetermined coating liquid containing a coating film forming component such as a resist or an interlayer insulating film on the surface of a substrate.

  Conventionally, in a photoresist process, which is one of semiconductor manufacturing processes, a predetermined coating solution such as a resist is applied to the surface of a substrate such as a semiconductor wafer (hereinafter referred to as “wafer”), exposed, and then developed with a developer. A mask pattern is formed on the surface. Such processing is generally performed using a system in which an exposure apparatus is connected to a coating / developing apparatus that performs resist coating / development.

  One technique for applying a coating solution such as a resist to the surface of the wafer is a spin coating method. The outline of the coating unit applied to this method will be briefly described with reference to FIG. First, the coating liquid supply source sent through the supply path 11 in a state where the wafer W is held in a horizontal position on the spin chuck 1 and the coating liquid nozzle 10 is set at a position facing the surface of the wafer W. 12 For example, the coating liquid from the coating liquid tank is supplied from the coating liquid nozzle 10 to the center of the surface of the wafer W, and the wafer W is rotated about the vertical axis. Thus, the coating liquid is spread over the entire surface of the wafer W by relying on the centrifugal force of the rotating wafer W to form a coating film.

  By the way, when a coating film having a desired target thickness is formed on the surface of the wafer W, the set value of the concentration of the coating film forming component contained in the coating liquid becomes an important process parameter. Conventionally, coating solutions of various concentrations corresponding to various film thicknesses are prepared, and a plurality of coating systems are incorporated in the apparatus so that coating solutions of various concentrations can be independently supplied to the wafer W. A predetermined supply system is selected from among the target film thickness target values, and an optimum concentration of coating solution is supplied to the wafer W. Therefore, a plurality of coating systems exist in the apparatus, and as a result, the problem that the apparatus configuration becomes complicated has been pointed out.

  In order to solve the above problem, for example, as shown in FIG. 14, the upstream side of the supply path 11 is branched, and the stock solution tank 13 for storing the stock solution of the coating solution and the solvent for storing the concentration adjustment solution, for example, the thinner Each of the tanks 14 is connected to a branch path, and a mixing means such as a line mixer 15 is arranged downstream of the mixing block 15a, which is a junction of the raw solution supply path and the solvent supply path. There is known a method of preparing a coating solution having an optimum concentration according to the target value of the film thickness by changing the mixing ratio (see Patent Document 1). If this method is used, coating solutions having various concentrations can be prepared simply by preparing a stock solution and a solvent, and there is an advantage that a plurality of supply systems need not be provided in the apparatus.

  However, in the above-described method, depending on the length of the supply path 11, after changing the mixing ratio, the coating liquid interposed in the flow path from the line mixer 15 to the discharge port of the coating liquid nozzle 10 is replaced. A slight amount of time is required until a coating liquid having a predetermined concentration is discharged from the discharge port. If a coating liquid that does not have a predetermined concentration is applied to the wafer W by mistake, the film thickness is reduced. A non-uniform coating film may be formed in the surface, resulting in an increase in the number of useless wafers W that cannot be produced as a product, resulting in high costs. Therefore, it is necessary to determine whether or not the coating liquid discharged from the coating liquid nozzle 10 has settled to a predetermined concentration, that is, whether or not the optimal coating liquid can be applied to the wafer W.

  On the other hand, inspecting the application state of the wafer W after application has been conventionally performed. As an example, for example, an inspection unit including an optical sensor is separately provided, and the wafer after application obtained by this sensor is provided. A method is known in which an image on the surface of W is analyzed to determine the presence or absence of coating failure (see Patent Document 2). An outline of this type of inspection unit will be briefly described with reference to FIG. First, the wafer W coated with the coating liquid is placed horizontally on the mounting table 2 provided in the inspection unit, and the surface of the wafer W is irradiated with predetermined light on the surface of the wafer W by the illumination 21. The line sensor 22 receives the reflected light that has been reflected at the time, and thereby acquires an image of the part that reflects the light. Then, an image over the entire surface of the wafer W is acquired by sliding the mounting table 2 relative to the line sensor 22. The acquired image is subjected to predetermined image processing such as binarization and an algorithm, for example, in the image processing unit 23, and the presence or absence of application failure is determined based on the processing result.

  However, in the above-described method, when a large number of wafers W are processed, the application of the subsequent wafer W is started after waiting for the previously applied wafer W to be carried into the inspection unit and the inspection result to be output. In this case, the throughput of the apparatus is reduced. Therefore, while the previously applied wafer W is inspected by the inspection unit, the actual condition is that the application processing of subsequent wafers W is sequentially performed in the application unit. Therefore, when it is determined that there is a coating defect in the result of the inspection of the previous wafer W, there is a concern that the subsequent wafer W may be wasted depending on the cause of the coating defect. That is, there is a trade-off problem between ensuring the throughput and effectively reflecting the inspection result on the subsequent wafer W.

JP-A-10-272407 (paragraph 0044, FIG. 6) Japanese Unexamined Patent Publication No. 2000-9655 (paragraphs 0006 to 0008, FIG. 1)

  That is, an object of the present invention is to quickly inspect whether or not there is uneven coating on a substrate after coating, when a coating solution obtained by dissolving a coating film forming component in a solvent is coated on the surface of the substrate. An object of the present invention is to provide a coating film forming apparatus and a coating film forming method.

The coating film forming apparatus of the present invention is a coating film forming apparatus that forms a coating film by applying a coating solution obtained by dissolving a coating film forming component in a solvent to the surface of a substrate.
A housing having a substrate holding part for holding the substrate horizontally;
Through the transfer port formed on the side wall of the housing, the substrate before the coating liquid is applied is transferred to the substrate holding unit, and the substrate for which the coating liquid is applied is moved forward and backward Flexible substrate transfer means;
A coating liquid nozzle that is provided in the housing and applies a coating liquid to the surface of the substrate held by the substrate holder;
Provided on the upper side of the advancing / retreating path of the substrate transfer means, and acquiring image data of the surface of the substrate when the substrate transfer means is moving forward to deliver the substrate before coating to the substrate holder And image acquisition means for acquiring image data of the surface of the substrate when the substrate after application is retracted to carry it out of the housing;
A liquid mixing means connected to the coating liquid nozzle via a flow path, for mixing the coating liquid and a concentration adjusting liquid for adjusting the concentration of the coating liquid;
Determination means for determining the presence or absence of uneven coating on the surface of the substrate based on comparison information between the image data of the substrate after application and the image data of the substrate before application;
Means for discharging the coating liquid from the coating liquid nozzle and replacing the liquid interposed between the liquid mixing means and the coating liquid nozzle when it is determined that there is uneven coating on the surface of the substrate; It is characterized by having.

Further, the image acquisition means is a line sensor having a light receiving portion that is equal to or longer than the width of the effective area of the substrate, and further, the substrate is moved below the line sensor by the substrate transfer means. The image data may be acquired. Furthermore , the structure which further provided the means to perform marking on the board | substrate determined with the application | coating nonuniformity on the surface of a board | substrate may be sufficient. In addition, “marking” means adding information that there is uneven coating to the history information of the substrate stored in the control unit, or physically marking any part of the substrate. Means.

The coating method of the present invention is a coating film forming method for forming a coating film by applying a coating solution obtained by dissolving a coating film forming component in a solvent to the surface of a substrate.
A step of advancing the retractable substrate transfer means and delivering the substrate before the coating liquid is applied to the substrate holding part provided in the housing having the transport port formed on the side wall thereof through the transport port When,
Obtaining image data of the surface of the substrate when the substrate transfer means is moving forward to deliver the substrate to the substrate holding unit;
A step of mixing the coating liquid and a concentration adjusting liquid for adjusting the concentration of the coating liquid by a liquid mixing means connected to the coating liquid nozzle via a flow path;
Applying a coating liquid obtained by mixing by the liquid mixing means to the surface of the substrate held horizontally in the substrate holding section by the coating liquid nozzle;
A step of retracting the substrate transfer means through the transport port to unload the substrate after the coating liquid has been applied;
Acquiring image data of the surface of the substrate when the substrate transfer means is retracted;
Determining the presence or absence of uneven coating on the surface of the substrate based on comparison information between the image data of the substrate after application and the image data of the substrate before application;
A step of discharging the coating liquid from the coating liquid nozzle and replacing the liquid interposed between the liquid mixing means and the coating liquid nozzle when it is determined that there is uneven coating on the surface of the substrate. And

  According to the present invention, the image data of the surface of the substrate is acquired when the substrate after application is taken out from the substrate platform by the substrate transfer means, and the presence or absence of coating unevenness is determined based on the image data. By adopting the configuration, it is possible to quickly detect the coating unevenness on the surface of the substrate, and to effectively reflect the result on the subsequent substrate to be processed next.

  A coating film forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. In the figure, reference numeral 3 denotes a housing forming an apparatus exterior body having a wafer transfer port 30 for loading and unloading a substrate, for example, a wafer W on the side surface. In addition, a spin chuck 31 that forms a substrate mounting portion for holding the substrate horizontally is provided so as to be movable up and down and rotatable about a vertical axis. The spin chuck 31 is connected to a drive mechanism 33 via a shaft portion 32, and is configured to be able to move up and down and rotate while the wafer W is supported by the drive mechanism 33.

  A cup body 4 is provided on the outer periphery of the wafer W held by the spin chuck 31 so as to surround the wafer W. The upper end of the cup body 4 is inclined inward. Furthermore, the tip part is bent downward. Moreover, the bottom part of the cup body 4 is formed with a liquid receiving portion 41 having a concave shape over the entire circumference. The liquid receiving portion 41 is partitioned by a partition wall 42 into an outer region and an inner region over the entire circumference, and a drain for discharging a drain of stored coating liquid or the like at the bottom of the outer region. A liquid port 43 is provided, and an exhaust port 44 is provided in the inner region.

  A circular plate 45 is provided on the lower side of the wafer W, and a ring member 46 is provided so as to surround the outer side of the circular plate 45. The outer end surface of the ring member 46 is bent downward, and the liquid, for example, the coating liquid spilled from the wafer W is guided along the surface of the ring member 46 into the outer region of the liquid receiving portion 41. ing. Although not shown, for example, three substrate support pins 47 that support the back side of the wafer W and can be moved up and down are provided so as to protrude and retract through the circular plate 45 up and down. 47 is configured such that the wafer W is transferred to the spin chuck 31 by the cooperative action with the transfer arm A which is a substrate transfer means entering from the outside of the housing 3 through the wafer transfer port 30. Yes.

  Further, a coating liquid nozzle 5 having a small-diameter discharge port 50 facing the central portion of the surface of the wafer W held by the spin chuck 31 via a gap is provided so as to be movable up and down and back and forth. The coating liquid nozzle 5 is connected to a supply path 51 such as one end of a pipe, and the other end of the supply path 51 is branched in the middle. Each branch path is a coating liquid supply source 52 such as a coating liquid tank and the coating liquid tank. A concentration adjusting solution for adjusting the concentration of the solution, for example, a solvent supply source 53 such as thinner, for example, is connected to a solvent tank. Furthermore, in the middle of the supply path 51 interposed between the mixing block 54a provided at the confluence of the flow path of the coating liquid and the solvent and the coating liquid nozzle 5, the mixing liquid and the solvent are mixed. Mixing means such as a line mixer 54 is provided. In the middle of each branch path in the supply path 51, liquid transfer means, for example, bellows pumps 55 and 56, each having a flow rate adjustable by changing the discharge stroke, are provided. Although not shown, the line mixer 54 is configured by arranging a plurality of baffle plates in the length direction of the cylindrical tube, for example. These baffle plates are formed, for example, by right-twisting or left-twisting a plate-like body having substantially the same width as the inner diameter of the cylindrical tube in the length direction. However, in the present invention, it is sufficient if the liquids can be mixed, and the mixing means is not limited to the line mixer 54. Further, the configuration is not limited to the configuration in which the line mixer 54 and the mixing block 54a are provided separately, and may be configured integrally.

  The coating liquid nozzle 5 is detachably supported on one end side of the nozzle arm 6, and is connected to a moving base 61 having a lifting mechanism (not shown) on the other end side of the nozzle arm 6 (see FIG. 2). ). Further, the movable base 61 is configured to be slidable in the lateral direction along the guide member 62 disposed along the longitudinal direction (Y direction) on the bottom surface of the housing 3, for example. That is, the coating solution nozzle 5 is configured to be movable between a position facing the center of the wafer W and a nozzle standby position outside the outer peripheral edge of the wafer W on the spin chuck 31. . At this nozzle standby position, for example, a discharge liquid receiving portion (not shown) is provided for receiving the discharged liquid when the coating liquid is discharged (discharged) from the discharge port 50 to replace the liquid in the supply path 51. .

  Further, in the vicinity of the upper side of the wafer transfer port 30 in the housing 3, an image of the surface of the wafer W carried in and out of the housing 3 by the transfer arm A through the wafer transfer port 30 before the coating liquid is applied. Light irradiation means that forms part of the image acquisition means for acquiring data and image data of the surface after the coating liquid is applied, for example, an illumination 71 capable of emitting monochromatic light of a predetermined wavelength and the illumination 71 For example, a line sensor 72 having a light receiving portion 72a for receiving reflected light of the light irradiated on the wafer W at the lower end thereof is provided. More specifically, the line sensor 72 is formed to have a length equal to or greater than the width of the effective area (device forming area) of the wafer W, and the illumination 71 is also equal to the width of the effective area of the wafer W. Alternatively, they are formed to have a length greater than or equal to this width, and these are arranged side by side along the length direction of the wafer transfer port 30. In this example, the line sensor 72 is formed longer than the diameter of the wafer W. The light from the illumination 71 is not particularly limited, but it is preferable to select monochromatic light having a wavelength that does not alter the components in the coating solution. Further, an optical filter may be provided between at least one of the line sensor 72 and the wafer W and between the illumination 71 and the wafer W.

When, for example, a strip-shaped light is irradiated from the illumination 71 to the surface of the wafer W positioned below the line sensor 72, the reflected light is received by the line sensor 72, so that the light on the surface of the wafer W is reflected. An image of the reflected part is acquired. Further, the wafer W is intermittently moved by the transfer arm A in a direction intersecting the length direction of the line sensor 72, and an image of the next part in the moving direction is acquired. By repeating this, an image of the entire surface of the wafer W is acquired. These images are wired or wirelessly transmitted to an image processing unit 74 provided in the control unit 73, stored as image data in the image processing unit 74, and more specifically, predetermined image processing described later, for example, binarization processing The surface information obtained by converting the surface state of the wafer W into a numerical value is acquired. That is, the illumination 71, the line sensor 72, and the image processing unit 74 constitute image acquisition means for acquiring image data of the surface of the wafer W. The control unit 73 also has a function of controlling operations of the drive mechanism 33, the moving base 61, the bellows pumps 54 and 55, the substrate support pins 47, the transfer arm A, and the like.

  The image processing unit 74 will be described in detail with reference to FIG. For convenience of explanation, the image processing unit 74 is schematically illustrated by function in FIG. 3, but the image processing unit 74 is actually configured by a computer system including a CPU. In the figure, reference numeral 8 denotes a memory for temporarily storing an image acquired by the line sensor 72. Reference numeral 80 denotes an image data storage unit for storing an image of the surface of the wafer W before application and an image of the surface of the wafer W after application as image data for each wafer. Reference numeral 81 denotes a history information storage unit for storing information such as the type of process processing performed on the wafer W and processing conditions thereof, that is, processing history information for each wafer. No. 82 inspects whether or not the coating liquid discharged from the discharge port 50 has settled to a predetermined concentration when the mixing ratio of the coating liquid and the solvent is changed, that is, the degree of mixing of the liquid and the degree of replacement in the flow path. This is a mode switching unit for the operator to switch between the first inspection mode and the second inspection mode for inspecting whether or not the wafer W processed during the process processing can be used as a product. .

  Reference numeral 83 denotes a storage unit that stores a processing program that is read when the first inspection mode is selected. The storage unit 83 acquires image data of the wafer W before and after coating. An image acquisition program 83a that performs image processing, for example, binarizes the acquired image data to acquire information on the surface state of the wafer W, and whether or not the concentration of the coating liquid has settled based on the surface state information Is stored. A storage unit 84 stores a processing program that is read when the second inspection mode is selected. The storage unit 84 stores an image acquisition program that acquires image data of the wafer W before and after coating. 84a, the obtained image data is subjected to image processing, for example, binarization to obtain information on the surface state of the wafer W, and whether or not the wafer W can be used as a product based on the information on the surface state And a history information creation program 84d for storing the determination result in the history information storage unit 81 is stored.

Furthermore, reference numeral 85 in the drawing is a storage unit for storing a threshold setting value read when the image data is binarized, for example, as will be described in detail later. Reference numeral 86 denotes a display unit such as a display for the operator to visually check the inspection result. 87 is a CPU. Reference numeral 88 denotes a unit controller for controlling the lighting operation of the illumination 71 and the transfer operation of the transfer arm A. 89 is a bus.

  Here, as an example of the image processing performed by the image processing unit 74, a method of binarizing image data will be described with reference to FIG. FIG. 4A schematically shows the surface of the wafer W to which the coating liquid has been applied, and the film thickness of the part corresponding to the region Q is thicker than the film thickness of the part outside the area Q. And That is, the region Q corresponds to coating unevenness. Here, when the line sensor 72 is scanned from one end to the other end of the surface of the wafer W as described above, for example, an image of the surface of the wafer W divided into the divided regions 200 corresponding to the pixels of the line sensor 72 is obtained. To be acquired. The acquired image is transmitted to the image processing unit 74, and binarization processing of each divided region 200 is performed based on luminance information that is one of the elements constituting the image. That is, as shown in FIG. 4B, for example, “0” is assigned to the luminance between the predetermined upper limit threshold value and the lower limit threshold value, and those not between these values are assigned, for example, By assigning “1”, binary digitized information of “0” or “1” is assigned to each of the divided areas over the entire surface of the wafer W. If the thickness is large, the luminance decreases, and conversely, if the thickness is small, the luminance increases. Therefore, the luminance within the region Q falls below the lower limit threshold value and is assigned logic “1”. On the other hand, when the thickness is small, the logic “1” is assigned exceeding the upper threshold.

  That is, the upper and lower luminance threshold values correspond to the upper and lower limits of the allowable range of film thickness to be formed on the surface of the wafer W. How to set this threshold is, for example, by actually forming coating films of various thicknesses on the surface of the wafer W on which a clean pattern is not formed in advance, and measuring the brightness of the wafer W in advance. It is preferable to decide by Note that since the brightness changes as the thickness of the coating film changes, the optimum threshold setting value also changes depending on the target thickness value. Furthermore, when the allowable range of in-plane uniformity varies depending on the type of coating liquid (that is, coating film), the upper and lower threshold widths may be changed. Therefore, for example, a threshold value corresponding to the target value of the film thickness, the type of coating solution, or a combination thereof is determined by performing an experiment, for example, and information on the threshold value is stored in the storage unit 85 for inspection. Sometimes, it may be read out.

  The same processing is performed on information obtained by imaging the surface of the wafer W before coating, and “0” or “1” binary information is assigned to each of the divided regions 200. However, in the case of the wafer W before coating, the in-plane luminance variation is not caused by coating unevenness, but is caused by surface contamination, a pattern shape or the like when a pattern is formed. Therefore, the set value of the threshold value does not need to be the same as that after coating. For example, the brightness of the surface of the wafer W on which a clean pattern is not formed is measured in advance, and the brightness is set appropriately above and below this brightness. The lower limit threshold value may be set by setting the upper limit threshold value with the specified width.

  Subsequently, when the substrate, for example, the wafer W is processed using the above-described coating film forming apparatus, for example, the wafer W of a certain lot is processed, and then the next lot of wafers W is processed before the next lot. Whether or not the coating liquid from the discharge port 50 has settled to the expected concentration when the mixing ratio of the coating liquid and the solvent is changed so as to obtain an optimum concentration according to the target value of the film thickness of the wafer W. The step of inspecting the above using the first inspection mode will be described with reference to FIG. First, a carrier storing a plurality of test wafers W made of, for example, 25 bare silicon is prepared, and the mode switching unit 82 is set to the first inspection mode by the operator's hand, for example, and inspection is started. . The test wafer W is not limited to bare silicon, and any substrate may be used as long as it is not transparent.

  Subsequently, when the transfer arm A takes out one wafer W from the carrier, the wafer W is loaded into the housing 3 through the wafer transfer port 30 (step S1), and the wafer W is delivered to the spin chuck 31. The wafer W passes below the illumination 71 and the line sensor 72, and a surface image of the wafer W before coating is acquired (step S2). More specifically, first, when one end of the wafer W1 is positioned below the line sensor 72 (image acquisition start position), the image acquisition program 83a is read out, the illumination 71 is turned on, and the surface of the wafer W is striped. The line sensor 72 receives the reflected light that has been irradiated and reflected by the surface of the wafer W and acquires an image of the portion that reflects the light. Further, the wafer W is moved to sequentially acquire images of the next part in the moving direction. At this time, since the image acquisition by the line sensor 72 is sufficiently fast, the image is acquired while the wafer W is substantially continuously moved. By performing this operation up to the other end of the wafer W, the illumination 71 is turned off when an image of the entire surface of the wafer W is acquired. The acquired image is converted into digital information by a converter (not shown), transmitted to the image processing unit 74, and stored in the image data storage unit 80 as image data before coating. Further, in the image processing unit 74, the surface information acquisition program 83b is read to perform binarization processing of the image data, and the processing result is stored in the image data storage unit 80 as surface information before coating (step S3). .

  Subsequently, the wafer W is transferred to the spin chuck 31 by the cooperative action of the transfer arm A and the substrate support pins 47 (not shown), and the back side thereof is sucked and sucked and held in a horizontal posture. On the other hand, the transfer arm A that has transferred the wafer W moves backward through the wafer transfer port 30. Thereafter, when the coating liquid nozzle 5 is set at a position facing the center of the surface of the wafer W, the coating liquid is discharged from the discharge port 50 and the drive mechanism 33 rotates the wafer W around the vertical axis at a predetermined rotational speed. Rotate to The coating liquid spreads toward the peripheral edge by the action of the centrifugal force of the rotating wafer W, and the coating liquid is applied to the surface of the wafer W in a thin film by further shaking off the coating liquid. It is formed (step S4).

  Thereafter, when the transfer arm A enters the housing 3 via the wafer transfer port 30 and receives the wafer W from the spin chuck 31 and unloads it from the housing 3, the image acquisition program 83 a is read, and the wafer W A surface image of the wafer W after coating is acquired by passing under the line sensor 72 and the illumination 71 (step S5). Information on the image of the wafer W after coating is transmitted to the image processing unit 74, stored as image data after coating in the image data storage unit 80, and further subjected to binarization processing of the image data. The surface information of the wafer W is stored in the image data storage unit 80 (step S6). The image data acquired before and after application is not limited to one, and a plurality of data may be acquired by reciprocating the lower part of the line sensor 72 by the transfer arm A. Further, when the image is being acquired, the transport speed of the transport arm A may be decreased, and otherwise the transport speed may be returned to the original speed.

  Subsequently, the determination program 83c is read out. First, the alignment (surface alignment and phase alignment of the wafer image) of the surface information after coating acquired in step S6 and the surface information before coating acquired in step 3 is performed. ) Is obtained, difference information which is comparison information obtained by subtracting the surface information before application from the surface information after application is obtained, and the presence or absence of application unevenness is determined based on the difference information (step 7). This will be described in detail with reference to FIG. First, when an image before coating is acquired, for example, as shown in FIG. 6A, if there is a dirty region (region Q1) on the surface of the wafer W, binarization is performed depending on the level of contamination. A logic “1” may be assigned to this area when processed. Further, when the coating liquid is applied to the wafer W, as shown in FIG. 6B, for example, if uneven application (region Q2) occurs, the image of the wafer W is binarized, so that the region Q2 and the region Q1 A numerical value of “1” may be assigned to both. In this case, if it is determined that the region Q1 is uneven coating, false detection is detected, but by subtracting the image information before coating from the image information after coating, logic "1" is assigned due to factors other than coating unevenness. For example, as shown in FIG. 6C, the remaining information is used as surface information (difference information).

  If there is no divided area 200 to which the logic “1” is assigned to the surface information (difference information), it is determined that there is no uneven application. Conversely, if there is an area to which the logic “1” is assigned, application unevenness is present. It is determined that there is. However, even if there is an area to which logic “1” is assigned, for example, the number of corresponding areas is less than or equal to a predetermined allowable range, or a place where the corresponding area exists is outside the device formation area. In some cases, it may be determined that there is no coating unevenness.

  However, the method for obtaining the difference information before and after coating does not necessarily need to use the method described above. In other words, any method can be used as long as it can exclude those assigned with logic “1” due to factors other than uneven coating. As an example of another method, for example, after correcting the brightness of the wafer after coating based on the in-plane variation of the brightness of the wafer W before coating, binarization processing is performed based on the corrected brightness. Obtaining difference information can be mentioned.

  If it is determined in step S7 that there is no coating unevenness, the process wafer (corresponding to step S4) is started by switching from the test wafer W to the product wafer W (step S8). In the process process, as will be described later in detail, the mode switching unit 82 is switched, and the coating unevenness is detected in the second inspection mode. On the other hand, if it is determined in step S7 that there is uneven coating, the next test wafer W is loaded into the apparatus, and the processing from step S2 to S7 is performed (step S9). Before the next wafer W is processed, a predetermined amount, for example, a used amount of coating liquid for one wafer W is discharged (discharged) from the coating liquid nozzle 5 at the nozzle standby position. The liquid may be replaced. Such a configuration is advantageous in that the number of test wafers W can be reduced.

  According to the above-described embodiment, the image acquisition means is disposed in the vicinity of the wafer transfer port 30 in the housing 3, and the image of the surface of the wafer W acquired when the wafer W is transferred in and out by the transfer arm A. By adopting a configuration that detects the presence or absence of coating unevenness based on the data, for example, the inspection of the wafer W can be performed in a shorter time compared with the case of inspecting with an inspection unit provided separately. Can be effectively reflected in the processing of the subsequent wafer W. In particular, by acquiring image data while the wafer W is being loaded / unloaded by the transfer arm A, the loading / unloading operation of the wafer W and the image acquisition operation can be used together, so that the time required for inspection of coating unevenness can be shortened. Therefore, the present invention is extremely effective in that the inspection result can be more reliably reflected in the processing of the subsequent wafer W.

  Further, according to the above-described embodiment, the coating process is actually performed using the test wafer W, and the coating liquid discharged from the coating liquid nozzle 5 is scheduled based on the inspection result of the coating unevenness on the surface. By determining whether or not the concentration has settled, that is, the mixed state of the liquid and the degree of replacement of the liquid in the flow path, the determination can be made with high accuracy. For this reason, for example, it is possible to prevent the application liquid that is not sufficiently mixed with the concentration adjustment liquid or the liquid mixed with the application liquid having a different concentration from being erroneously applied to the product wafer W. It can be very small. In other words, since it is possible to form a film by applying the coating liquid in an optimum state for the wafer W, it is possible to form a coating film with high film thickness uniformity in the surface.

The reason why the state of the liquid can be determined with high accuracy will be described with reference to FIG. 7, taking as an example a case where the concentration of the concentration adjusting liquid is increased to lower the concentration of the coating liquid. However, this does not limit the present invention. First, immediately after switching the mixing ratio, a coating solution having a high concentration is present in the supply path 51, so that the coating film formed on the first wafer W is thick. The film thickness is substantially close to the target value, and is within the allowable range from the third wafer W. On the other hand, the in-plane uniformity of the film thickness falls within an allowable range from the fourth wafer with a slight delay. As described above, there is a time difference between the film thickness and the in-plane uniformity of the film thickness within the allowable range. The inventors pay attention to the fact that coating unevenness occurs on the surface of the wafer W when mixing and replacement are insufficient and the in-plane uniformity of the film thickness is outside the allowable range, and image data of the wafer W after coating is obtained. By obtaining and detecting the coating unevenness, it was possible to determine the mixed state of the liquid with high accuracy. The inventors provided a viscometer in the middle of the supply path 51, and checked the concentration of the coating liquid based on the relationship between the viscosity and the concentration that was previously grasped. Although it is possible, it has been confirmed through experiments that it is quite difficult to determine even in-plane uniformity.

  Further, according to the above-described embodiment, the image data of the surface of the wafer W before and after coating is acquired, and the presence / absence of coating unevenness is determined based on the comparison information. Even if W or a wafer W with a pattern is used, it is possible to prevent the determination accuracy from being lowered due to the state of the substrate. That is, since only the fact that the wafer W is carried into the housing 3 and before it is carried out, that is, the fact that it is applied in the housing 3 can be examined, the result is higher accuracy. Application unevenness can be detected. Therefore, according to this example, in addition to the background of the wafer W, even if, for example, the lighting condition of the illumination 71 varies in the plane, the determination accuracy is not affected by these factors. The present invention is extremely effective in that it is not necessary to use. That is, since noise due to these factors is canceled, highly accurate detection can be performed.

  However, in the above-described embodiment, the configuration is not necessarily limited to the configuration in which the first inspection mode is performed using the test wafer W. For example, the product wafer W may be used. In this case, even if it is a product wafer W with a pattern, for example, it is possible to eliminate the influence of the base by taking the difference between before and after the application, so that the same effect as in the above case can be obtained.

  Furthermore, in the above-described embodiment, if the setting value of the mixing ratio is changed for each lot, the liquid in the supply path 51 is replaced as schematically shown in FIG. 7, for example. Since the amount of liquid to be discharged can be known, the amount of coating liquid corresponding to this amount can be discharged (discharged) from the coating liquid nozzle 5 before processing the test wafer W. In this case, it is a good idea because the number of test sheets can be reduced.

  Furthermore, in the above-described embodiment, the configuration is not necessarily limited to the configuration in which image data before coating is acquired for each wafer W, and for example, only the image after coating is acquired using a test wafer W with a clean surface and no pattern. Then, the coating unevenness may be determined based on the processing result of the acquired image. Even in this case, the same effects as those described above can be obtained. Further, in this example, image data before coating is acquired only for the first test wafer W, and image data of the first wafer W is used for the second and subsequent wafers W. May be.

  Next, a process of inspecting using the second inspection mode for determining whether or not the processed wafer W can be used as a product during the process will be described with reference to FIG. However, with the exception of the fact that the wafer W is changed from a test one to a product one, the same steps as those in the first inspection mode described above are used, and the reference numerals of the corresponding steps are given as references. Detailed description will be omitted. First, for example, when it is determined that there is no coating unevenness in the first inspection mode, for example, a carrier containing a large number of wafers W for products, for example, 25 sheets, is prepared and process processing is started. For example, the inspection of the wafer W to be processed is started by setting the mode switching unit 82 to the second inspection mode by the operator's hand.

First, the transfer arm A takes out one product wafer W from a carrier (not shown) and loads it into the housing 3 through the wafer transfer port 30 (step S11 (see step S1)). And the surface image before application | coating is acquired through the lower side of the line sensor 72 (step S12 (refer step S2)). The acquired pre-application image data is stored in the image data storage unit 80, and further binarized by the image processing unit 74, and the processing result is stored in the image data storage unit 80 as surface information before application ( Step S13 (see Step S3)). Subsequently, the wafer W is transferred to the spin chuck 31, and the coating liquid is applied by the coating liquid nozzle 5 (step S4 (see step S4)).

  Thereafter, the transfer arm A enters the housing 3 and receives the wafer W from the spin chuck 31. The wafer W passes below the illumination 71 and the line sensor 72, and a surface image after coating is acquired ( Step S15 (see Step S5)). The acquired image data is stored in the image data storage unit 80, further binarized by the image processing unit 74, and the processing result is stored in the image data storage unit 80 as surface information after application (step S16 ( Step S6)). Subsequently, the determination program 83c is read, and difference information between the surface information before and after application is acquired, and the presence or absence of application unevenness is determined based on the difference information (step 17 (step S7)). Note that even if particles floating in the surrounding atmosphere or particles brought in from the coating liquid adhere to the surface of the wafer W, the coating unevenness is substantially detected. Also includes foreign objects.

When it is determined that there is no coating unevenness, the history information creation program 84d is read, and the information “no coating unevenness” is stored in the history information storage unit 81 as history information of the wafer W (step S18). If the unprocessed wafer W does not remain, the process is terminated (step S19). If the unprocessed wafer W remains, the next wafer W is loaded into the housing 3 and the processes from step S12 to step S17 are performed. Is performed (step S20). On the other hand, when it is determined that there is uneven coating, the history information creation program 84d is read, and the information “with uneven coating” is stored in the history information storage unit 81 as history information of the wafer W (step S18). If no unprocessed wafer W remains, the process is terminated (step S19). If an unprocessed wafer W remains, the next wafer W is carried into the apparatus, and the processes from step S12 to step S17 are performed. (Step S20). When processing of all the wafers W in the same lot is completed, the wafer W with uneven coating is extracted based on the history information, and the wafer W without uneven coating is sent to the next process. On the other hand, it is determined whether or not the wafer W with uneven coating is to be disposed by performing a detailed inspection (step S18). If it is determined that there is uneven application, an alarm may be sounded to warn the operator, and if the degree of uneven application is further large, that is, the number of assigned areas of logic “1” is too large. In some cases, an interlock for stopping the apparatus may be operated by the control unit 73. Further, if the assignment of the information on the presence / absence of coating unevenness to the wafer W is called “marking”, the history information does not necessarily have to be software-attached to the history information as in this example. You may make it attach | subject a mark to any place of W.

  Even with such a configuration, it is possible to obtain the same effect as in the above case. Further, according to this example, based on the detection result of the coating unevenness, the wafer rotation speed by the spin chuck 31 is set to a predetermined value. It is also possible to determine whether or not Further, according to the present example, since the inspection result is stored in the history information of the wafer W, it is possible to easily distinguish the wafer W which cannot be a product. When a large number of wafers W are repeatedly processed, for example, it is quite difficult to control and separate the carrier W for returning the uneven wafer W and the carrier for returning the normal wafer W by the transfer arm A in terms of control. Even if the coating unevenness occurs, it is burdensome for the worker to stop the apparatus and separate the wafer W. Therefore, the configuration of the control system of the apparatus can be simplified by adopting a configuration in which after the wafers W of the same lot are processed at once as shown in this example, those with uneven coating are extracted based on the history information. This is a good idea because it can reduce the burden on the operator.

  In the above-described embodiment, it is not always necessary to acquire image data before application of all wafers W. For example, image data before application of only the first wafer W of a lot is acquired, and other wafers W in the same lot are acquired. With respect to, application failure may be determined using the image data of the leading wafer W. Since product wafers are kept clean and rarely soiled, it is often the base material and pattern that affect the brightness. Therefore, for the case where the same pattern is formed on the same base, throughput can be improved by omitting acquisition of image data before coating.

  Furthermore, in the present invention, the line sensor is not limited to the configuration in which an image is acquired while being transferred to the transfer arm A. For example, the line sensor is configured such that the wafer W is supported by the spin chuck 31 or the substrate support pins 47 and is slidable. 72 and the illumination 71 may be scanned from one end to the other end of the wafer W to acquire an image. Even if it is such a structure, the effect similar to the above-mentioned case can be acquired. However, as in the above-described example, by acquiring an image while loading / unloading the wafer W by the transfer arm A, the loading / unloading operation of the wafer W and the image acquisition operation can be combined, and as a result, throughput is improved. This is a good idea.

  Further, in the present invention, the image acquisition means is not limited to the configuration provided with the line sensor 72. For example, a line sensor camera extending in the diameter direction of the wafer W is disposed above the wafer W, and the line sensor camera is mounted on the wafer W. On the other hand, the image may be acquired by relatively rotating 180 °. Furthermore, a line sensor camera having a shorter length may be used, and a lens may be disposed under the camera to secure an imaging region that spans the diameter of the wafer W. In addition, an image may be acquired by imaging the surface of the wafer W using a CCD camera. Even if it is such a structure, the effect similar to the above-mentioned case can be acquired. Furthermore, in the case of using a CCD camera, the image data is not limited to the configuration in which the image is acquired while being supported by the transfer arm A. For example, the image data before and after application may be acquired while being placed on the spin chuck 31. Good. As an apparatus configuration in this case, for example, as shown in FIG. 9, the CCD camera 8 is disposed above the peripheral edge of one end of the wafer W on the spin chuck 31, and above the other end sandwiching the center of the wafer W. A planar illumination 81 is disposed on the surface of the wafer W, and the illumination 81 irradiates light on the entire surface of the wafer W, while the CCD camera 8 captures the entire surface of the wafer W and acquires image data. Even if it is such a structure, the effect similar to the above-mentioned case can be acquired.

  Furthermore, in the present invention, the present invention is not limited to the configuration in which the presence / absence of application unevenness is determined based on the difference information between the image data after application and before application, and may be determined based only on image data after application. Even if it is such a structure, the effect similar to the above-mentioned case can be acquired. However, if there is a concern that the accuracy may change due to the influence of the substrate, for example, a clean and unpatterned wafer W is used in the first inspection mode, and a test is performed in advance in the second inspection mode. By determining how much the brightness changes depending on the pattern shape (pattern density, etc.) of the base, and correcting the brightness according to the pattern shape formed on the wafer W to be inspected, the base Can reduce the effects of

  Further, in the present invention, the difference is taken after binarization, but the difference may be taken first and binarized later. Further, the image processing is not limited to the binarization processing, and for example, processing such as considering the degree of deviation using the absolute value of the deviation from the threshold value or the square value as it is may be performed. Further, in the present invention, color image data may be obtained by acquiring R, G, and B image data. In this case, the determination may be made based on at least one of R, G, and B data.

  The present invention can also be applied to a heat treatment of a substrate other than the semiconductor wafer W, such as an LCD substrate or a photomask reticle substrate, as the substrate to be processed. Furthermore, the coating solution is not limited to a resist, and any coating solution can be used as long as the coating film forming component is dissolved in a solvent. Specific examples of other coating solutions include a coating solution for forming an insulating film. .

  Finally, an example of a coating / developing apparatus incorporating the coating film forming apparatus of the present invention as a coating unit will be briefly described with reference to FIGS. In the figure, B1 is a carrier placement section for carrying in and out of carrier C1 in which, for example, 25 wafers W serving as substrates are hermetically stored, and a carrier station provided with a placement section 90a on which a plurality of carriers C can be placed. 90, an opening / closing part 91 provided on the wall surface in front of the carrier station 90, and a delivery means A1 for taking out the wafer W from the carrier C1 through the opening / closing part 91.

  A processing unit B2 surrounded by a casing 92 is connected to the back side of the carrier mounting unit B1, and the processing unit B2 is a shelf unit in which heating / cooling system units are arranged in stages from the front side. U1, U2 and U3 and main transfer means A2 and A3 (corresponding to transfer arm A) which are substrate transfer means for transferring wafers W between processing units including a coating / developing unit described later are alternately arranged. Is provided. That is, the shelf units U1, U2, U3 and the main transfer means A2, A3 are arranged in a line in the front-rear direction when viewed from the carrier mounting part B1, and an opening for wafer transfer (not shown) is formed at each connection part. Thus, the wafer W can freely move in the processing section B1 from the shelf unit U1 on one end side to the shelf unit U3 on the other end side. The main transport means A2 and A3 include one surface portion on the shelf unit U1, U2 and U3 side arranged in the front-rear direction when viewed from the carrier placement portion B1, and one surface on the right side liquid processing unit U4 and U5 side which will be described later. It is placed in a space surrounded by a partition wall 93 composed of a part and a back part forming one surface on the left side. In the figure, reference numerals 94 and 95 denote temperature / humidity adjusting units including a temperature adjusting device for the processing liquid used in each unit, a duct for adjusting the temperature and humidity, and the like.

  For example, as shown in FIG. 11, the liquid processing units U4 and U5 are coatings in which the above-described coating film forming apparatus is unitized on a storage portion 96 that forms a space for supplying a chemical solution such as a coating solution such as a resist solution or a developing solution. The unit COT, the developing unit DEV, the antireflection film forming unit BARC, and the like are stacked in a plurality of stages, for example, five stages. In addition, the above-described shelf units U1, U2, and U3 are configured such that various units for performing pre-processing and post-processing of the processing performed in the liquid processing units U4 and U5 are stacked in a plurality of stages, for example, 9 stages. The combination includes a post-exposure heating unit (PEB), a heating unit for heating (baking) the wafer W, a cooling unit for cooling the wafer W, and the like.

  An exposure unit B4 is connected to an inner side of the shelf unit U3 in the processing unit B2 through an interface unit B3 including, for example, a first transfer chamber 97 and a second transfer chamber 98. In addition to the two delivery means A4 and A5 for delivering the wafer W between the processing unit B2 and the exposure unit B4, a shelf unit U6 and a buffer carrier C0 are provided inside the interface unit B3.

  An example of the wafer flow in this apparatus is as follows. First, when the carrier C1 storing the wafer W is placed on the mounting table 90a from the outside, the lid of the carrier C1 is removed together with the opening / closing portion 91, and the delivery means A1. Thus, the wafer W is taken out. Then, the wafer W is transferred to the main transfer means A2 via a transfer unit (not shown) that forms one stage of the shelf unit U1, and is pre-processed as a coating process on one shelf in the shelf units U1 to U3. For example, an antireflection film forming process and a cooling process are performed. Thereafter, the coating liquid is applied by the coating unit, and further, a coating defect is inspected and stored in the history information. Then, the wafer W on which the coating film is formed is heated (baked) by a heating unit that forms one shelf of the shelf units U1 to U3, and after being cooled, the wafer W is transferred to the interface unit B3 via the delivery unit of the shelf unit U3. It is carried in. In this interface section B3, the wafer W is transferred to the exposure section B4 through a path of transfer means A4 → shelf unit U6 → transfer means A5, for example, and exposure is performed. After the exposure, the wafer W is transferred to the main transfer means A2 through the reverse path, and developed by the developing unit DEV to form a resist mask. Thereafter, the wafer W is returned to the original carrier C1 on the mounting table 90a, and the wafer W determined as having a coating defect is extracted.

It is a longitudinal cross-sectional view which shows the coating film-forming apparatus which concerns on embodiment of this invention. It is a top view which shows the coating film-forming apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the image process part of the said coating film-forming apparatus. It is explanatory drawing which shows typically the process performed by the said image process part. It is process drawing which shows the procedure which processes a board | substrate using the said coating film-forming apparatus. It is explanatory drawing which shows a mode that surface information is obtained based on each image data before application | coating and after application | coating. It is explanatory drawing which shows typically a time-dependent change of a film thickness and in-plane uniformity. It is process drawing which shows the other procedure which processes a board | substrate using the said coating film-forming apparatus. It is explanatory drawing which shows the other example of the image acquisition means of the said coating film-forming apparatus. It is a top view which shows the coating / developing apparatus in which the coating film-forming apparatus of this invention is integrated. 1 is a perspective view showing a coating / developing apparatus in which a coating film forming apparatus of the present invention is incorporated. It is explanatory drawing which shows a mode that a coating liquid is spin-coated on the surface of a board | substrate. It is explanatory drawing which shows an example of the conventional coating device. It is explanatory drawing which shows the outline of the conventional board | substrate inspection method.

Explanation of symbols

W Wafer A Transfer arm 30 Wafer transfer port 31 Spin chuck 5 Coating liquid nozzle 52 Stock solution supply source 53 Solvent supply source 71 Illumination 72 Line sensor 74 Image processing unit

Claims (6)

In a coating film forming apparatus for forming a coating film by applying a coating solution obtained by dissolving a coating film forming component in a solvent to the surface of a substrate,
A housing having a substrate holding part for holding the substrate horizontally;
Through the transfer port formed on the side wall of the housing, the substrate before the coating liquid is applied is transferred to the substrate holding unit, and the substrate for which the coating liquid is applied is moved forward and backward Flexible substrate transfer means;
A coating liquid nozzle that is provided in the housing and applies a coating liquid to the surface of the substrate held by the substrate holder;
Provided on the upper side of the advancing / retreating path of the substrate transfer means, and acquiring image data of the surface of the substrate when the substrate transfer means is moving forward to deliver the substrate before coating to the substrate holder And image acquisition means for acquiring image data of the surface of the substrate when the substrate after application is retracted to carry it out of the housing;
A liquid mixing means connected to the coating liquid nozzle via a flow path, for mixing the coating liquid and a concentration adjusting liquid for adjusting the concentration of the coating liquid;
Determination means for determining the presence or absence of uneven coating on the surface of the substrate based on comparison information between the image data of the substrate after application and the image data of the substrate before application;
Means for discharging the coating liquid from the coating liquid nozzle and replacing the liquid interposed between the liquid mixing means and the coating liquid nozzle when it is determined that there is uneven coating on the surface of the substrate; A coating film forming apparatus comprising the coating film forming apparatus.   The image acquisition means is a line sensor having a light receiving portion that is equal to or longer than the width of the effective area of the substrate, and further, the substrate is moved below the line sensor by the substrate transfer means and the image is obtained. Data is acquired, The coating film-forming apparatus of Claim 1 characterized by the above-mentioned.   3. The coating film forming apparatus according to claim 1, further comprising means for marking the substrate determined to have uneven coating on the surface of the substrate. In a coating film forming method for forming a coating film by applying a coating solution obtained by dissolving a coating film forming component in a solvent to the surface of a substrate,
A step of advancing the retractable substrate transfer means and delivering the substrate before the coating liquid is applied to the substrate holding part provided in the housing having the transport port formed on the side wall thereof through the transport port When,
Obtaining image data of the surface of the substrate when the substrate transfer means is moving forward to deliver the substrate to the substrate holding unit;
A step of mixing the coating liquid and a concentration adjusting liquid for adjusting the concentration of the coating liquid by a liquid mixing means connected to the coating liquid nozzle via a flow path;
Applying a coating liquid obtained by mixing by the liquid mixing means to the surface of the substrate held horizontally in the substrate holding section by the coating liquid nozzle;
A step of retracting the substrate transfer means through the transport port to unload the substrate after the coating liquid has been applied;
Acquiring image data of the surface of the substrate when the substrate transfer means is retracted;
Determining the presence or absence of uneven coating on the surface of the substrate based on comparison information between the image data of the substrate after application and the image data of the substrate before application;
A step of discharging the coating liquid from the coating liquid nozzle and replacing the liquid interposed between the liquid mixing means and the coating liquid nozzle when it is determined that there is uneven coating on the surface of the substrate. A coating film forming method.   5. The coating film forming method according to claim 4, wherein the image data of the surface is acquired by passing under a line sensor having a light receiving portion that is equal to or longer than the width of the effective area of the substrate.   The coating film forming method according to claim 4, further comprising a step of marking a substrate that is determined to have uneven coating on the surface of the substrate.

Images