JP2006024882A - Apparatus and method for thin-film application, and apparatus and method for exposing liquid immersion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a proper quality resist pattern on a wafer without causing defects. <P>SOLUTION: A chemical 3, supplied from a liquid supply source through a particle filtration apparatus 9, is discharged from a discharge nozzle 6 onto the surface of the wafer. A particulate-measuring apparatus 13 is interposed on a pipe line between the particle filtration apparatus 9 and the discharge nozzle 6 for measuring the amount of particulate matter, such as air bubbles and particles contained in the chemical 3. Further, there are provided a data collecting unit 15 for always collecting controlled voltage values of a solenoid control valve 10 for opening and closing piping and measured values of the particulate measuring apparatus 13, and a calculation apparatus 16 for calculating the measured result of the particulate-measuring apparatus 13. The calculation apparatus 16 calculates the number of particles in the particulate matter contained in the chemical applied per one wafer, and compares the number of particles in the particulate matter with a standard value to determine whether the thin-film application apparatus is stopped. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thin film coating apparatus and an immersion exposure apparatus for forming a resist pattern on a wafer when manufacturing a semiconductor wafer.

  Conventionally, in a photolithography process for manufacturing a semiconductor wafer, 1) a resist coating process in which a photoresist is coated on the wafer surface to form a resist film having a uniform thickness, and 2) a solvent mixed in the photoresist is evaporated. And a pre-bake process that solidifies the resist film to improve adhesion with the base and enhance photochemical reactivity, and 3) an exposure process that irradiates the wafer with ultraviolet rays through a photomask to burn a device pattern on the resist. And 4) a development process in which the photoresist in the unexposed portion is dissolved with a developer to form a photoresist pattern, and 5) a post-bake process in which the photoresist swollen by development is cured to improve the adhesion to the ground. ing. In recent years, with the miniaturization of patterns, 6) a coating process for further forming an antireflection film on a photoresist is performed. In general, when applying a chemical solution such as a resist film or an antireflection film, a method of dropping the chemical solution while rotating the wafer is employed (see, for example, Patent Document 1).

  FIG. 10 is a diagram schematically showing the structure of a conventional thin film coating apparatus. As shown in FIG. 10, the conventional thin film coating apparatus includes a wafer rotating mechanism 102 that holds and rotates the wafer 101 horizontally, and a chemical solution applying mechanism 104 that conveys and drops the chemical solution 103. The wafer rotation mechanism 102 has a wafer chuck 105 and a motor flange 106. In the chemical solution application mechanism 104, a discharge nozzle 107 that drops the chemical solution 103 onto the wafer 101 and a chemical solution bottle 108 that is a supply source of the chemical solution 103 are communicated with each other through a pipe 109. A buffer tank 110, a pump 111, a particle filtering device 112, an electromagnetic control valve 113, and a chemical liquid level adjustment device 114 are interposed in the middle of the pipe 109 from the chemical solution bottle 108 side. The control device 118 controls the chemical solution application mechanism 104.

At the start of operation of the thin film coating apparatus, a chemical bottle 108 containing the chemical solution 103 is installed at a predetermined position, and a pipe 109 and an N ₂ pressurizing pipe 115 are connected to the chemical bottle 108 in a sealed state. Then, N _{2 is} pressurized from the N ₂ pressurizing pipe 115 and the buffer tank drain 116 is opened to fill the buffer tank 110 with the chemical solution 103. Thereafter, the valve of the buffer tank drain 116 is closed, and the valve of the particle filtration device drain 117 is opened to fill the pump 111 and the particle filtration device 112 with the chemical solution 103. Then, by driving the pump 111 in this state, the chemical liquid 103 reaches the discharge nozzle 107 via the chemical liquid level adjustment device 114. The chemical solution 103 that has reached the discharge nozzle 107 is dropped onto the rotating wafer 101 and applied with a uniform film thickness by centrifugal force. During this series of processing, the amount of particulate matter (hereinafter referred to as “fine particles”) such as bubbles and fine dust (particles) contained in the chemical solution 103 is measured by the fine particle measuring device 119. The fine particles diffusely scatter or scatter ultraviolet rays irradiated at the time of exposure in an exposure process in which the wafer 101 is irradiated with ultraviolet rays through a photomask to burn a device pattern on the resist. When such irregular reflection or confusion occurs, a defect occurs in the device pattern on the wafer 101, which may reduce the yield. In order to prevent this, the apparatus state of the thin film coating apparatus is confirmed from the measurement result of the fine particle measuring apparatus 119, and the operation or stop of the coating operation is determined based on the measurement result, and control according to the determination result is performed. If the above technology is used, it is possible to send an alarm signal to the operator or stop the coating operation automatically when fine particles are mixed due to disturbance such as equipment trouble. Can be avoided (see, for example, Patent Document 2).
JP 7-320999 A JP-A-10-240897

  However, the thin film coating apparatus as described above has the following two problems.

  Normally, when a single wafer 101 is processed, the chemical solution 103 has a uniform film thickness even after a certain amount of chemical solution is discharged and dropped once on the rotating wafer 101 and the discharge of the chemical solution 103 is stopped. The rotation of the wafer 101 is continued until For this reason, the actual discharge of the chemical solution 103 during the series of processes is discontinuous. On the other hand, the fine particle measuring device 119 that performs continuous measurement integrates the number of fine particles contained in the chemical solution 103 that passes through the fine particle measuring device 119 at a certain time (for example, every second) regardless of the discharge state of the chemical solution 103. It is a measured value. Therefore, the total number of fine particles in the chemical solution 103 actually discharged / dropped onto one wafer 101 is an integrated value of the number of measurements of the fine particle measuring device 119 while the chemical solution 103 is being discharged onto the wafer 101. . Since it is impossible to obtain the integrated value without knowing when the chemical solution 103 is discharged and when it stops, it is not possible to obtain the total number of fine particles in the chemical solution 103 discharged / dropped onto one wafer 101. .

  Further, depending on the structure or mechanism of the apparatus, it is difficult to install the particle measuring device 119 in the discharge nozzle 107, and it must be installed in the middle of the line. For this reason, the fine particles in the chemical solution 103 immediately before being dropped onto the wafer 101 cannot be measured. Specifically, as shown in FIG. 10, the chemical solution 103 containing fine particles detected by the fine particle measurement device 119 is transferred from the fine particle measurement device 119 to the electromagnetic control valve 113, the chemical liquid level adjustment device 114, and the discharge nozzle 107. After being passed through the pipe 109 connecting the two, they are dropped on the wafer 101. Therefore, the chemical solution 103 detected by the fine particle measuring device 119 is not discharged onto the wafer 101 being processed at that time, but is discharged onto the wafer 101 after several discharges. Thus, there is a delay corresponding to the capacity between the particle measuring device 119 and the discharge nozzle 107. Therefore, the number of fine particles contained in the chemical solution 103 discharged onto each wafer 101 needs to be calculated in consideration of a delay corresponding to the volume between the fine particle measuring device 119 and the discharge nozzle 107.

  The present invention provides a wafer with a high-quality resist pattern that does not contain defects by taking a means for more accurately grasping the number of fine particles contained in a chemical solution or liquid and taking a means for more reliably removing bubbles. The purpose is to form.

  A thin film coating apparatus according to the present invention is a thin film coating apparatus that forms a thin film by discharging a chemical supplied from a chemical supply source through a particle filtering device through a discharge nozzle and applying it to a wafer surface, A pipe connecting between the discharge nozzle, an electromagnetic control valve for opening and closing the pipe, a fine particle measuring device for measuring the number of particulate substances (particles and bubbles) contained in the chemical liquid in the pipe, A data collection unit that collects the control voltage value of the electromagnetic control valve and the measurement value of the particle measuring device, and the control voltage value and the measurement value collected by the data collection unit are applied to one wafer. And an arithmetic circuit for calculating the number of the particulate substances contained in the chemical solution.

  In the thin film coating apparatus of the present invention, the control voltage value of the electromagnetic control valve may be information that changes the voltage value so that the state of the flow of the chemical solution to be examined can be understood. In addition, the arithmetic unit judges the state of the chemical flow from the control voltage value of the electromagnetic control valve, and calculates the total number of fine particles per discharge of the chemical from the measured value and time of the fine particle measuring device while the chemical is flowing It has a function to perform processing.

  In the thin film coating apparatus of the present invention, in order to calculate the number of particulate substances contained in the chemical applied to one wafer, it is determined whether to stop the thin film coating apparatus based on the value. be able to. That is, when a chemical solution containing a large amount of fine particles or bubbles suddenly flows through the chemical solution line due to disturbance such as equipment trouble, the thin film coating apparatus can be automatically stopped. Therefore, the occurrence of resist pattern defects can be prevented in advance.

  Furthermore, since the particulate matter in the chemical solution can be measured in real time while the product is being processed, it is always possible to automatically determine whether the device is normal or abnormal. When this apparatus is used, compared with the conventional method in which the particulate matter in the film is measured by a surface defect inspection apparatus after forming a thin film on the monitor wafer, the work time of the operator is reduced. Shortening and yield improvement are possible. Furthermore, since the particulate matter in the chemical solution can be measured without stopping the operation of the apparatus, the operation rate of the apparatus can be improved.

  In the arithmetic circuit, it is preferable that the number of the particulate substances contained in the chemical solution applied per one wafer is compared with a predetermined standard value.

  The thin film coating method of the present invention is a thin film coating method using a thin film coating apparatus that forms a thin film by discharging a chemical supplied from a chemical supply source through a particle filtration device through a discharge nozzle and applying the solution onto a wafer surface. Collecting a control voltage value of an electromagnetic control valve provided in a pipe connecting between the particle filtering device and the discharge nozzle, and determining whether or not the chemical solution is applied to the wafer surface (a) And a step (b) of measuring the number of particulate matter contained in the chemical liquid flowing through the pipe, and a wafer is applied to the wafer based on the results of the step (a) and the step (b). A step (c) of calculating the number of the particulate substances contained in the chemical solution, and a step (d) of determining whether to stop the thin film coating apparatus based on the result of the step (c) Be equipped And wherein the Rukoto.

  In the thin film coating method of the present invention, the thin film coating apparatus can be automatically stopped when a chemical liquid containing a large amount of particulate matter suddenly flows through the chemical liquid line due to disturbance such as equipment trouble. Therefore, the occurrence of resist pattern defects can be prevented in advance.

  Furthermore, since it is possible to measure the particulate matter in the chemical solution at the time of product processing in real time, it is possible to always automatically determine whether the apparatus is normal or abnormal. Therefore, compared with the conventional method in which the particulate matter in the film is measured with a surface defect inspection device after the thin film is formed on the monitor wafer, the working time of the worker is reduced and the yield is improved. It becomes possible. Furthermore, since the particulate matter in the chemical solution can be measured without stopping the operation of the apparatus, the operation rate of the apparatus can be improved.

  In addition, in order to calculate the number of particulate matter in the chemical applied to each wafer, the delay until the chemical that was measured by the particle measuring device is actually released from the discharge nozzle is grasped. It is preferable to keep it. More specifically, it is only necessary to know how many wafers after the wafer being processed at that time the chemical solution to be measured by the particle measuring apparatus is applied.

  In the chemical solution application method of the present invention, in the step (d), the number of the particulate substances contained in the chemical solution applied per wafer is compared with a preset standard value. Even after making a judgment and judging that the thin film coating apparatus is stopped, the comparison of the number of the particulate substances contained in the chemical applied to one wafer and the standard value is continued. It is preferable to stop the thin film coating apparatus until it is determined that the number of the state substances is within a normal range. In this case, since the drainage can be continued automatically until the original normal state with a small number of particulate matter is obtained, the burden on the operator can be reduced. Further, compared to the conventional case where a fixed amount of liquid is discharged by the operator's operation, the chemical solution is discharged by a more appropriate amount. Thereby, the time for performing drainage can be minimized, and the operating rate can be improved.

  In the immersion exposure apparatus of the present invention, a mask pattern is placed on the wafer from the tip of the optical element in a state where the space between the tip of the optical element and the wafer surface in the projection optical system is filled with a liquid (pure water or the like). An immersion exposure apparatus for transferring the liquid to the wafer surface, a liquid discharge nozzle for supplying the liquid to the wafer surface, a pipe connecting the liquid supply source and the liquid discharge nozzle, and an electromagnetic for opening and closing the pipe. A control valve; a particle filtration device interposed in the middle of the pipe; and a bubble removal device that is interposed between the particle filtration device and the liquid discharge nozzle in the pipe and removes bubbles in the liquid. It is characterized by.

  In general, when particulate matter such as bubbles is present in the liquid on the wafer, exposure light is scattered by the particulate matter, pattern formation is not performed according to the reticle pattern, and pattern defects that reduce the yield occur. To do. In the immersion exposure apparatus of the present invention, since the bubbles are removed by the bubble removing apparatus, the occurrence of pattern defects can be prevented more reliably. In addition, since only the gaseous molecules are selectively removed in the bubble removing device, the liquid composition / flow rate does not change.

  Further, the immersion exposure apparatus of the present invention is interposed between the bubble removing device and the liquid discharge nozzle in the pipe, a fine particle measuring device for measuring the amount of particulate matter contained in the liquid, A data collection unit that collects the control voltage value of the electromagnetic control valve and the measurement value of the particle measuring device, and the control voltage value and the measurement value collected by the data collection unit are supplied per wafer. And an arithmetic circuit for calculating the number of the particulate substances contained in the liquid. In this case, the immersion exposure apparatus can be stopped if air bubbles are suddenly mixed into the liquid due to disturbance such as equipment trouble. Furthermore, since it is possible to measure the particulate matter in the liquid during product processing in real time, it is possible to always automatically determine whether the apparatus is normal or abnormal. When this apparatus is used, compared to the conventional method in which pattern defects are measured with a surface defect inspection apparatus after performing a series of processes such as resist coating, exposure and development on the monitor wafer, the operator's The working time and the yield can be improved. Furthermore, since the particulate matter in the liquid can be measured without stopping the operation of the apparatus, the operation rate of the apparatus can be improved.

  A specific exposure method using the immersion exposure apparatus of the present invention includes a step (a) of determining whether or not the liquid is supplied to the wafer surface by collecting control voltage values of the electromagnetic control valve. ), A step (b) of measuring the number of particulate matter contained in the liquid flowing through the pipe, and a supply per wafer based on the results of the step (a) and the step (b). A step (c) of calculating the number of the particulate matter contained in the liquid and a step of determining whether to stop the immersion exposure apparatus based on the result of the step (c) (d) ).

  In the exposure method of the present invention, in the step (d), the number of the particulate matter contained in the liquid supplied per wafer is compared with a preset standard value. Even after making the determination and determining to stop the immersion exposure apparatus, continue the comparison between the number of the particulate matter contained in the liquid supplied per wafer and the standard value, It is preferable that the immersion exposure apparatus is stopped until it is determined that the number of the particulate matter is within a normal range. In this case, since the drainage can be continued automatically until the original normal state with a small number of particulate matter is obtained, the burden on the operator can be reduced. Further, as compared with the conventional case where a certain amount of liquid is discharged by the operator's operation, the liquid is discharged by a more appropriate amount. Thereby, the time for performing drainage can be minimized, and the operating rate can be improved.

  According to the thin film coating apparatus and the immersion exposure apparatus according to the present invention, a high-quality resist pattern that does not include defects can be formed on the wafer, and the yield can be improved.

(First embodiment)
Hereinafter, the first embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic view showing the configuration of a thin film coating apparatus in the first embodiment of the present invention. The thin film coating apparatus of the present embodiment includes a wafer rotation mechanism 2 that holds and rotates the wafer 1 horizontally, and a chemical solution coating mechanism 20 that transports and drops the chemical solution 3. The wafer rotation mechanism 2 includes a wafer chuck 4 that holds the wafer 1 and a motor flange 5 that rotates the wafer chuck 4. The chemical solution application mechanism 20 is provided in the middle of the pipe 7, a discharge nozzle 6 that drops the chemical solution 3 on the wafer 1, a pipe 7 that connects the discharge nozzle 6 and a supply source (not shown) of the chemical liquid 3. A pump 8, a particle filtering device 9, a fine particle measuring device 13 for measuring fine particles in the chemical liquid 3, an electromagnetic control valve 10, and a chemical liquid level adjustment device 11 are provided. The chemical liquid level adjustment device 11 adjusts the chemical liquid level in the discharge nozzle 6 and sucks it by applying a negative pressure to prevent dripping from the tip of the discharge nozzle 6 after discharging a predetermined amount. It has a suck back function. As will be described later, the control device 12 is a device that controls the chemical solution application mechanism 20, and only a part of the control line 12a is shown for the sake of simplicity. The fine particle measuring device 13 detects fine particles contained in the chemical liquid 3 passing through the fine particle measuring device 13 at a certain time, integrates the detected number and time, and outputs data.

  This thin film coating apparatus is different from the conventional one in that a data collecting unit 15 that constantly collects a control voltage value of the electromagnetic control valve 10 that opens and closes the pipe 7 and a measurement value of the fine particle measuring apparatus 13, and an electromagnetic control valve The voltage conversion circuit 14 which converts the control voltage of 10 into voltage and the arithmetic unit 16 which calculates the measured value are provided.

  FIGS. 2A to 2C are time chart diagrams showing the chemical flow rate in the piping, the open / close state of the electromagnetic control valve, and the time variation of the control voltage value during wafer processing in the first embodiment. The electromagnetic control valve 10 is normally closed when the apparatus is stopped or in a standby state. However, when the chemical solution 3 is flown during wafer processing, the electromagnetic control valve 10 is opened and the pump 8 is driven to discharge the chemical solution 3. Therefore, only when the electromagnetic control valve 10 is opened as shown in FIG. 2 (b), the flow rate of the chemical solution 3 becomes a certain value as shown in FIG. 2 (a), as shown in FIG. 2 (c). Further, the control voltage value that controls the opening / closing operation of the electromagnetic control valve 10 is also displaced from 0 v to 20 v. Further, since the electromagnetic control valve 10 is closed when the chemical solution 3 is stopped, the control voltage value is displaced from 20v to 0v. From this fact, by continuously monitoring the control voltage value of the electromagnetic control valve 10, the discontinuous discharge state of the chemical liquid 3 can be grasped. In addition, although the case where the control voltage value of the electromagnetic control valve 10 changes from 0 to 20v was described here, this voltage value may be any value as long as the discharge state can be grasped. In addition, it may be impossible to directly input a large voltage value such as 20 v into the data collection unit 15 or the like depending on the specifications on the input side (guaranteed value of the data collection unit 15 or the like). In that case, the required voltage of the electromagnetic control valve 10 can be reduced to a desired voltage value through the voltage conversion circuit 14 and input to the data collection unit 15 or the like.

  Next, a method for measuring fine particles in the chemical solution 3 in the present embodiment will be described. FIGS. 3A and 3B are diagrams showing the relationship between the open / close state of the electromagnetic control valve and the total number of fine particles in the chemical applied to one wafer in the first embodiment. As shown in FIG. 3A, during the processing of one wafer, the discharge of the chemical liquid 3 is discontinuous, and the electromagnetic control valve 10 repeats the opening / closing operation. When the number of particles measured by the particle measuring device 13 is taken in by the data collection unit 15 and integrated by the arithmetic device 16 while the electromagnetic control valve 10 is open, as shown in FIG. The total number of fine particles in the chemical solution 3 discharged / dropped per sheet can be obtained. Details of the calculation method will be described later.

  FIG. 4 is a graph showing the change in the total number of fine particles in the chemical applied to one wafer and the number of pattern defects on the wafer in the first embodiment. As shown in FIG. 4, the increase / decrease in the number of fine particles and the number of pattern defects follow the same increase / decrease transition with the difference in the number of processings for five wafers. This is because the electromagnetic control valve 10, the chemical liquid level adjustment device 11, the discharge nozzle 6, and the pipe 7 connecting them are provided between the particle measuring device 13 and the discharge nozzle 6. That is, the fine particles measured by the fine particle measuring device 13 take a time required to process five wafers, and the electromagnetic control valve 10, the chemical liquid level adjustment device 11 and the discharge nozzle 6 and the piping connecting them. This is because it passes through 7 and drops onto the wafer.

  Note that the data shown in FIG. 4 includes the volume of the chemical liquid 3 held between the particle measuring device 13 and the discharge nozzle 6, that is, the electromagnetic control valve 10, the chemical liquid level adjustment device 11, the discharge nozzle 6, and those. It is the result of having measured the discharge amount of the chemical | medical solution 3 once as 3 ml using the apparatus whose capacity | capacitance in the piping 7 to connect is 15 ml. In this case, since the fine particles measured by the fine particle measuring device 13 through the processing for five wafers pass between the fine particle measuring device 13 and the discharge nozzle 6, the delay in the discharge nozzle 6 is equivalent to five treatments. Thus, how late the fine particles measured by the fine particle measuring device 13 reach the discharge nozzle 6 depends on the capacity between the fine particle measuring device 13 and the discharge nozzle 6 and the discharge amount of the chemical solution 3 at one time. If you know, you can estimate.

  Based on this knowledge, the correlation shown in FIG. 5 can be obtained in consideration of the delay for five processes. FIG. 5 is a graph showing the correlation between the measurement value obtained by the fine particle measuring apparatus and the number of pattern defects on the wafer in the first embodiment.

  Based on the correlation shown in FIG. 5, the number of fine particles corresponding to an arbitrary allowable value of the number of pattern defects on the wafer is obtained and determined as a standard value. The “number of fine particles” is a value obtained by adding the number of bubbles and the number of particles. Since both cause pattern defects on the wafer, they are handled in the same row. In FIG. 5, the standard value is 90 fine particles corresponding to 150 on-wafer pattern defects.

  Control using such a prescribed value will be described with reference to FIG. FIG. 6 is a flowchart showing steps of controlling the thin film coating apparatus using the standard value in the first embodiment. In the method of the present embodiment, first, in step S1, the number of fine particles in the chemical solution 3 is measured by the fine particle measuring device 13, and in step S2, the data collection unit 15 taking in the control voltage value of the electromagnetic control valve 10 is electromagnetically operated. It is determined whether the chemical solution 3 is applied from the control voltage value of the control valve 10. If it is determined that the chemical solution 3 is applied, in step S3, the measurement result of the fine particle measuring device 13 while the chemical solution 3 is applied is taken into the data collection unit 15 and then integrated by the arithmetic device 16.

  Next, in step S4, the measurement value integrated by the arithmetic unit 16, that is, the determination for comparing the number of fine particles contained in the chemical solution 3 applied per wafer (one discharge) with the standard value is calculated. This is done with the device 16. If the number of fine particles is less than the standard value, a normal operation command is output in step S5, and the thin film coating apparatus is normally operated. On the other hand, if it is determined in step S4 that the number of fine particles is greater than or equal to the standard value, an abnormal stop command is output from the arithmetic unit 16 to the control device 12 in step S6, the thin film coating apparatus is abnormally stopped, and the discharge nozzle 6 The chemical liquid 3 is discharged from the other area. At this time, the fine particles are discharged together with the chemical solution 3. Here, in step S7, as in the normal operation of the coating apparatus, a determination is always made for the discharged chemical solution 3 to compare the number of fine particles against a standard value. Operate the device normally, and continue draining if it exceeds the standard value.

  In the present embodiment, the thin film coating apparatus can be automatically stopped when the chemical liquid 3 containing a large amount of fine particles or bubbles suddenly flows through the chemical liquid line due to disturbance such as equipment trouble. Therefore, the occurrence of resist pattern defects can be prevented in advance.

  Furthermore, since the fine particles in the chemical solution 3 can be measured in real time while the wafer 1 is being processed, it is always possible to automatically determine whether the apparatus is normal or abnormal. Therefore, it is possible to shorten the working time and improve the yield of the operator as compared with the conventional method in which the thin film is formed on the monitor wafer and the fine particles in the film are measured by a surface defect inspection apparatus or the like. Furthermore, since the fine particles in the chemical solution 3 can be measured without stopping the operation of the apparatus, the operation rate of the apparatus can be improved.

  Further, at the time of abnormality, the chemical liquid 3 is automatically drained until the fine particles become below the standard value. Therefore, compared with the case where a fixed amount of liquid is drained by an operator's operation in the past, the chemical liquid 3 is drained by a more appropriate amount. Furthermore, since the number of fine particles in the chemical solution 3 can be confirmed while draining, the time can be shortened.

  FIG. 7 is a graph showing the relationship between the number of fine particles in the chemical solution and the number of killer defects per wafer in the first embodiment. The number of killer defects here refers to only those that reduce the device yield among the pattern defects generated by the fine particles in the chemical solution 3 in a device having a gate length size of 0.15 μm and a pattern occupation ratio of 54.4%. It is counted. Since the relationship between the number of fine particles and the number of killer defects that lowers the yield can be seen from FIG. 7, if an arbitrary standard value is set for the number of fine particles, the product can be processed with an allowable number of killer defects or less.

(Second Embodiment)
Below, the 2nd Embodiment of this invention is described, referring drawings.

  FIG. 8 is a schematic diagram showing a configuration of an exposure apparatus using an immersion exposure method in the second embodiment. In the exposure apparatus shown in FIG. 8, the illumination optical system 31 includes an exposure light source such as an ArF excimer laser or a KrF excimer laser, an optical integrator, a field stop, and a condenser lens. The exposure light 32 emitted from the illumination optical system 31 illuminates the pattern provided on the reticle 33. The reticle 33 is held by a reticle stage 34, and the pattern of the reticle 33 is reduced and projected onto a wafer 38 coated with a photoresist via a lens barrel 35 and a projection optical system lens 36.

  The wafer 38 is placed on a wafer stage 39, and the space between the wafer 38 and the projection optical system lens 36 is filled with a liquid 37 such as pure water. When the space between the two is filled with the liquid 37, the exposure wavelength can be substantially shortened to improve the resolution, and the depth of focus can be substantially widened. The liquid 37 is supplied through a pipe 53 from a supply source (not shown) of the liquid 37. In this pipe 53, fine particles such as bubbles in the liquid 37, a pump 47, a particle filtering device 46, a bubble removing device 44 that selectively removes bubbles in the liquid 37, in order from the side closer to the supply source of the liquid 37. A fine particle measuring device 45 for measuring, an electromagnetic control valve 43 and a liquid discharge nozzle 40 are provided.

  Although not shown, the bubble removing device 44 has a structure in which the inside is divided into two spaces by a special film having high gas selective permeability. One of the two spaces is directly connected to the pipe 53 and the other is connected to the vacuum pump 52. In the bubble removing device 44, the other space is evacuated by the vacuum pump 52 in a state where the liquid 37 is passed through one of the two spaces connected to the pipe 53. Thereby, the bubbles contained in the liquid 37 pass through the highly gas-selective membrane and move to the other space, and are further exhausted to the outside by the vacuum pump 52.

  The liquid 37 filled on the wafer 38 is recovered by the liquid recovery device 42 via the liquid inflow nozzle 41 after the exposure is completed. The exposure apparatus also converts the control voltage value of the electromagnetic control valve 43 that opens and closes the pipe 53 and the data collection unit 49 that constantly collects the measurement value of the particle measuring device 45, and the voltage conversion of the control voltage of the electromagnetic control valve 43. A voltage conversion circuit 48 to be operated, a calculation device 50 for calculating a measurement value of the particle measuring device 45, and a control device 51 for controlling discharge and stop of the liquid 37.

  If fine particles such as bubbles are present in the liquid 37 on the wafer 38 in the immersion exposure apparatus, the exposure light 32 is scattered by the fine particles, so that pattern formation is not performed according to the reticle pattern. In this case, pattern defects that reduce the yield occur. In the present embodiment, most of the particles and bubbles are filtered by the particle filtering device 46, and bubbles remaining after passing through the particle filtering device 46 are removed by the bubble removing device 44. Thereby, generation | occurrence | production of a pattern defect can be suppressed more reliably. Note that since the bubble removing device 44 selectively removes only gaseous molecules as described above, the composition and flow rate of the liquid 37 does not change.

  Further, even if a large amount of bubbles are suddenly mixed into the liquid 37 due to disturbance such as equipment trouble, the apparatus is stopped by using the same fine particle measurement method and control method as described in the first embodiment. It is possible to drain automatically. The specific method will be described below. First, the data collection unit 49 determines whether the liquid 37 is supplied from the control voltage value of the electromagnetic control valve 43. If it is determined that the liquid 37 is supplied, the measurement result of the fine particle measuring device 45 while the liquid 37 is supplied is taken into the data collection unit 49, and then the measurement result and time are integrated by the arithmetic unit 50. .

  Next, the arithmetic unit 50 makes a determination to compare the measured value integrated by the arithmetic unit 50, that is, the number of fine particles contained in the liquid 37 supplied per wafer (one discharge) with a standard value. Is called. If the number of fine particles is less than the standard value, a normal operation command is output, and the immersion exposure apparatus is normally operated. On the other hand, if it is determined that the number of fine particles is equal to or greater than the standard value, an abnormal stop command is output from the arithmetic unit 50 to the control unit 51, the immersion exposure apparatus is abnormally stopped, and the liquid 37 is discharged from the discharge nozzle 6 to another area. Is discharged. At this time, the fine particles are discharged together with the liquid 37. At this time, as in the case of normal operation of the exposure apparatus, a determination is always made for the discharged liquid 37 to compare the number of fine particles against the standard value. Operate and continue draining if it is above the specified value.

  FIG. 9 shows a result of measuring the total use time of the bubble removing device in the exposure apparatus shown in FIG. 8 and the number of particulate substances contained in the liquid after passing through the bubble removing device in the fine particle measuring device. The graph which shows the relationship is shown. When the total use time of the bubble removing device 44 is increased, the bubble removing ability is lowered, and the number of bubbles in the liquid 37 after passing through the bubble removing device 44 is increased. It is necessary to replace it with a new bubble removing device. However, since the amount of bubbles and the amount of dissolved gas in the liquid 37 varies depending on the state of manufacture and transportation of the liquid 37, it is not desirable to make the replacement time constant. It can be seen from FIG. 9 that the bubble removing capability of the bubble removing device gradually decreases from a certain time. Therefore, if the measured value at a certain time when the bubble removing ability gradually decreases is used as a standard value, the replacement time of the bubble removing device can be predicted before the removal ability is lowered. Even if the amount of dissolved gas varies, it can be exchanged at an appropriate time.

  The present invention is useful for forming a high-quality resist pattern free of defects on a wafer.

It is the schematic which shows the structure of the thin film coating device in the 1st Embodiment of this invention. (A)-(c) is a time chart figure which shows the time fluctuation | variation of the chemical | medical solution flow rate in piping at the time of wafer processing, the open / close state of an electromagnetic control valve, and a control voltage value in 1st Embodiment. (A), (b) is a figure which shows the relationship between the opening-and-closing state of an electromagnetic control valve, and the total number of microparticles | fine-particles in the chemical | medical solution apply | coated per wafer in 1st Embodiment. In 1st Embodiment, it is a graph which shows the change of the total number of the microparticles | fine-particles in the chemical | medical solution apply | coated per wafer, and the number of pattern defects on a wafer. In 1st Embodiment, it is a graph which shows the correlation with the measured value in a microparticle measuring apparatus, and the number of pattern defects on a wafer. It is a flowchart figure which shows the step which controls a thin film coating device using a standard value in 1st Embodiment. In 1st Embodiment, it is a graph which shows the relationship between the number of fine particles in a chemical | medical solution, and the number of killer defects per wafer. In 2nd Embodiment, it is the schematic which shows the structure of the exposure apparatus using the immersion exposure method. In the exposure apparatus shown in FIG. 8, the relationship between the total use time of the bubble removing device and the result of measuring the number of particulate matter contained in the liquid after passing through the bubble removing device in the fine particle measuring device. The graph figure shown is shown. It is a figure which shows typically the structure of the conventional thin film coating device.

Explanation of symbols

1 wafer
2 Wafer rotation mechanism
3 chemicals
4 Wafer chuck
5 Motor flange
6 Discharge nozzle
7 Piping
8 Pump
9 Particle filtration equipment
10 Electromagnetic control valve
11 Chemical liquid level adjustment device
12 Control device
12a Control line
13 Fine particle measuring device
14 Voltage conversion circuit
15 Data collection unit
16 arithmetic unit
20 Chemical solution application mechanism
31 Illumination optics
32 Exposure light
33 reticle
34 Reticle stage
35 Tube
36 Projection optics lens
37 liquid
38 wafers
39 Wafer stage
40 Liquid discharge nozzle
41 Liquid inflow nozzle
42 Liquid recovery device
43 Solenoid control valve
44 Bubble remover
45 Particle measuring device
46 Particle Filter
47 Pump
48 Voltage conversion circuit
49 Data collection unit
50 arithmetic unit
51 Control device
52 Vacuum pump
53 Piping

Claims (8)

A thin film coating apparatus for forming a thin film by discharging a chemical liquid supplied from a chemical liquid supply source through a particle filtration device from a discharge nozzle and applying it to a wafer surface,
Piping connecting the particle filtration device and the discharge nozzle;
An electromagnetic control valve for opening and closing the pipe;
A fine particle measuring device for measuring the number of particulate substances contained in the chemical solution in the pipe;
A data collection unit for collecting a control voltage value of the electromagnetic control valve and a measurement value of the particle measuring device;
And an arithmetic circuit for calculating the number of the particulate matter contained in the chemical solution applied per wafer from the control voltage value and the measurement value collected in the data collection unit. A thin film coating apparatus.   The thin film coating according to claim 1, wherein the arithmetic circuit compares the number of the particulate substances contained in the chemical solution applied per wafer with a predetermined standard value. apparatus. A thin film coating method using a thin film coating apparatus for forming a thin film by discharging a chemical liquid supplied from a chemical liquid supply source through a particle filtration device from a discharge nozzle and applying it to a wafer surface,
Collecting a control voltage value of an electromagnetic control valve provided in a pipe connecting the particle filtering device and the discharge nozzle, and determining whether or not the chemical solution is applied to the wafer surface; ,
A step (b) of measuring the number of particulate matter contained in the chemical flowing through the pipe;
Based on the results of the step (a) and the step (b), the step (c) of calculating the number of the particulate matter contained in the chemical solution applied per one wafer,
And (d) determining whether to stop the thin film coating apparatus based on the result of the step (c). In the step (d), the determination is performed by comparing the number of the particulate substances contained in the chemical applied to one wafer and the standard value set in advance.
Even after determining that the thin film coating apparatus is to be stopped, the comparison between the number of the particulate substances contained in the chemical applied to one wafer and the standard value is continued, and the number of the particulate substances The thin film coating method according to claim 3, wherein the thin film coating apparatus is stopped until it is determined that the value is within a normal range. An immersion exposure apparatus for transferring a mask pattern from the tip of the optical element onto the wafer in a state where the space between the tip of the optical element and the wafer surface in the projection optical system is filled with liquid,
A liquid discharge nozzle for supplying the liquid to the wafer surface;
Piping connecting between the liquid supply source and the liquid discharge nozzle;
An electromagnetic control valve for opening and closing the pipe;
A particle filtration device interposed in the middle of the pipe;
An immersion exposure apparatus comprising: a bubble removing device that is interposed between the particle filtering device and the liquid discharge nozzle in the pipe and removes bubbles in the liquid. A fine particle measuring device that is interposed between the bubble removing device and the liquid discharge nozzle in the pipe and measures the amount of particulate matter contained in the liquid;
A data collection unit for collecting a control voltage value of the electromagnetic control valve and a measurement value of the particle measuring device;
And an arithmetic circuit for calculating the number of the particulate matter contained in the liquid supplied per wafer from the control voltage value and the measurement value collected in the data collection unit. Immersion exposure equipment. An immersion exposure method using the immersion exposure apparatus according to claim 5,
Determining whether the liquid is being supplied to the wafer surface by collecting control voltage values of the electromagnetic control valve; and
Measuring the number of particulate matter contained in the liquid flowing through the pipe (b);
A step (c) of calculating the number of the particulate matter contained in the liquid supplied per wafer based on the results of the step (a) and the step (b);
And (d) determining whether to stop the immersion exposure apparatus based on the result of the step (c). In the step (d), the determination is performed by comparing the number of the particulate substances contained in the liquid supplied per wafer and the standard value set in advance.
Even after determining that the immersion exposure apparatus is to be stopped, the comparison of the number of the particulate substances contained in the liquid supplied per wafer and the standard value is continued. 8. The immersion exposure method according to claim 7, wherein the immersion exposure apparatus is stopped until it is determined that the number is within a normal range.

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