JP2005136326A - System for predicting equipment condition and its method, and exposure equipment management system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system and a method for predicting changes in the condition of a substrate processing equipment, such as exposure equipment, from environmental changes. <P>SOLUTION: A plurality of the substrate processing equipment 11 and a maintenance management server 13 are installed in a substrate processing plant 10. Each substrate processing equipment 11 is provided with various kinds of sensors, to detect the environment of both the outside and the inside or the like (temperature, humidity, atmospheric pressure or the like). The maintenance management server 13 predicts the conditions of each substrate processing equipment 11, based on the relational expression showing a correlation between the change in environment, obtained beforehand and the change in condition of each substrate processing equipment 11, and based on detection results of the various kinds of the sensors. If a predicted result of the equipment condition is equal to a predetermined threshold or larger, the system gives a warning or transmits a control command to make the equipment condition adjusted, to the substrate processing equipment 11 of which the equipment condition has deteriorated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus state prediction apparatus and method for predicting an apparatus state of a substrate processing apparatus that processes a substrate such as a wafer or a glass plate, and a management system that manages an exposure apparatus that performs exposure processing of a substrate.

  A semiconductor element, a liquid crystal display element, an imaging element, a thin film magnetic head, and other devices are manufactured by performing various processes on a substrate such as a semiconductor wafer or a glass plate using a substrate processing apparatus. The processing performed on the substrate by the substrate processing apparatus includes, for example, a coating process in which a photosensitive agent such as a photoresist is applied, an exposure process in which an image of a mask or reticle pattern is projected and exposed on the substrate coated with the photosensitive agent, and an exposure process. For example, development processing for developing the processed substrate.

  The exposure process is performed by an exposure apparatus, and the coating process and the development process are performed by a coating / developing apparatus called a coater / developer in-line with the exposure apparatus. In addition, the substrate processing apparatus such as the above-described exposure apparatus includes an evaluation apparatus for evaluating the uniformity of patterns formed on the substrate subjected to the various processes described above or the degree of pattern overlap, and an electron beam applied to the substrate. In many cases, an inspection apparatus is provided for observing and inspecting a pattern formed on the substrate by detecting secondary electrons and backscattered electrons generated at the time.

  The above exposure apparatus needs to transfer the mask pattern with high overlay accuracy to the pattern already formed on the substrate at the time of exposure, so it is an automatic sensor that accurately detects the position and orientation of the substrate. A focus sensor and an alignment sensor are provided. The autofocus sensor detects the position and orientation of the substrate surface in the optical axis direction of the projection optical system by irradiating multiple points on the substrate with detection light from an oblique direction to the substrate and detecting the reflected light. Sensor.

  Further, the alignment sensor is provided on the side of the projection optical system, performs image processing on an image signal obtained by irradiating the detection light on the substrate and images the alignment mark formed on the substrate, and It is a sensor that detects the position of the alignment mark in a plane orthogonal to the optical axis. Since the alignment sensor is provided on the side of the projection optical system, during exposure, the baseline amount (the center of the exposure area of the projection optical system and the center of the measurement visual field of the alignment sensor) is detected with respect to the detection result of the alignment sensor. In consideration of the distance), the substrate is aligned with the exposure area of the projection optical system.

Usually, a device manufacturing factory is provided with a clean room, and a plurality of substrate processing apparatuses including the above-described exposure apparatus and the like are arranged in parallel in the clean room. In the clean room, the temperature and humidity are kept constant, so that fluctuations in the state of the substrate processing apparatus due to changes in the environment such as temperature and humidity and changes in the processing conditions when performing substrate processing are minimized. . For an exposure apparatus including an autofocus sensor and an alignment sensor, see, for example, Patent Document 1 below.
Japanese Patent Laid-Open No. 06-349708

  By the way, as described above, the temperature and humidity are kept constant in the clean room, but the state of the substrate processing apparatus may fluctuate due to slight fluctuations in the environment because the temperature and humidity are not kept constant. . For example, the position of the image plane of the projection optical system changes due to slight fluctuations in temperature and humidity, and the measurement error is affected by the optical components provided in the autofocus sensor described above or the mechanical mechanism that holds these components. Or fluctuations in the baseline amount. When a change in the position of the image plane of the projection optical system or a measurement error of the autofocus sensor occurs, an error occurs in alignment between the substrate surface and the image plane of the projection optical system, resulting in a focus error.

  Such a change in the state of the apparatus due to an environmental change causes a line width error of a pattern finally formed on the substrate or a deterioration in overlay accuracy, and causes a device defect. A fundamental measure for preventing such line width errors is to improve the configuration of the substrate processing apparatus itself so that the apparatus state of the substrate processing apparatus is less susceptible to environmental fluctuations. The work is extremely time-consuming work, and there is a problem that it is difficult to take countermeasures for a substrate processing apparatus that is already in operation.

  In addition, since the apparatus state cannot be grasped at present, even if the apparatus state allows the execution of the exposure process, the apparatus state is adjusted by performing calibration before performing the process. For example, in an exposure apparatus provided in a substrate processing apparatus, calibration of an autofocus sensor is always performed before exposure processing is performed on a lot-unit substrate. This calibration process is unnecessary when the apparatus is in an apparatus state in which the execution of the exposure process is allowed. Further, since the calibration process is performed for each lot, there is also a problem that the throughput is reduced.

  The present invention has been made in view of such problems of the prior art, and an apparatus state prediction apparatus and method, an apparatus state prediction program capable of predicting a change in the apparatus state of a substrate processing apparatus from an environmental change, An object of the present invention is to provide a computer-readable information recording medium on which the program is recorded, and an exposure apparatus.

  Hereinafter, in the description shown in this section, the present invention will be described in association with the member codes shown in the drawings representing the embodiments. However, each constituent element of the present invention is limited to the members shown in the drawings attached with these member codes. Is not to be done.

  In order to solve the above problems, an apparatus state prediction apparatus of the present invention is an apparatus state prediction apparatus (13) for predicting an apparatus state of a substrate processing apparatus (11) for processing a substrate (W), the substrate processing Environment information collecting means (DT1 to DT3, 101) for collecting environment information related to the environment of the apparatus, and a relational expression (Fm) indicating a correlation between the environmental change and the apparatus state change of the substrate processing apparatus are stored. A storage means (108), a prediction means (102) for predicting an apparatus state of the substrate processing apparatus based on the environmental information collected by the relational expression and the environment information collection means, and a prediction result of the prediction means Comparing means (103) for comparing the value with a predetermined threshold (Th), and executing means (104 to 106) for executing predetermined processing based on the comparison result of the comparing means

  In this case, it is preferable that the relational expression is a regression expression in which the environment is an explanatory variable and the apparatus state is an objective variable. In addition, apparatus information collecting means (101) for collecting apparatus information relating to the apparatus state of the substrate processing apparatus, and updating means for updating the relational expression stored in the storage means based on the environment information and the apparatus information ( 107).

  In addition, the execution means transmits the maintenance data including the prediction result to the management apparatus (21) that manages the substrate processing apparatus, and the transmission means (106) executes the transmission process. The prediction result exceeds the threshold value. Warning means (105) for executing a warning process when it is detected, and adjusting means (104) for executing an adjustment process of the apparatus state of the substrate processing apparatus when the prediction result exceeds the threshold value. .

  The environmental information collecting means detects at least one of temperature, humidity, and atmospheric pressure inside the substrate processing apparatus or at least one of temperature, pressure, and specific resistance of the liquid used in the substrate processing apparatus. Of the internal environment detection means, the external environment detection means for detecting at least one of the temperature, humidity and pressure outside the substrate processing apparatus, and the structure part temperature detection means for detecting the temperature of the structure part of the substrate processing apparatus Information detected by at least one is collected as the environmental information. Furthermore, the substrate processing apparatus can be an exposure apparatus that exposes and transfers a mask pattern onto the substrate, and the environmental information collecting means can collect the environmental information via a network.

  The apparatus state prediction method of the present invention is an apparatus state prediction method for predicting an apparatus state of a substrate processing apparatus (11) for processing a substrate (W), and is environmental information for collecting environmental information about the environment of the substrate processing apparatus. The substrate processing apparatus based on the collection step (S1), the relational expression showing the correlation between the environmental variation and the apparatus state variation of the substrate processing apparatus, and the environmental information collected in the environmental information collecting step. A prediction step (S2) for predicting the device state of the device, a comparison step (S3) for comparing the prediction result predicted in the prediction step with a predetermined threshold, and a predetermined process based on the comparison result in the comparison step The execution step (S4) which performs is included.

  In this case, the relational expression is preferably a regression expression in which the environment is an explanatory variable and the apparatus state is an objective variable. The apparatus further includes an apparatus information collecting step (S5) for collecting apparatus information relating to an apparatus state of the substrate processing apparatus, and an updating step (S8) for updating the relational expression based on the environment information and the apparatus information. It can be.

  In addition, the execution step (S4) includes a transmission step of executing a transmission process of maintenance data including the prediction result to a management apparatus that manages the substrate processing apparatus, and the prediction result exceeds the threshold value. A warning step of executing a warning process, and an adjustment step of executing an adjustment process of the apparatus state of the substrate processing apparatus when the prediction result exceeds the threshold value.

  The environmental information collected in the environmental information collecting step (S1) includes the temperature, humidity and pressure inside the substrate processing apparatus or the temperature, pressure, specific resistance of the liquid used in the substrate processing apparatus, It is desirable to set at least one of the temperature outside the substrate processing apparatus, the humidity and the atmospheric pressure, and the temperature of the structure part of the substrate processing apparatus.

  The exposure apparatus management system of the present invention is an exposure apparatus (30) management system for exposing and transferring a pattern of a mask (R) onto a substrate (W), and environmental measuring means (TD1 to TD1) for measuring environmental conditions inside and outside the exposure apparatus. TD3), storage means (108) for storing a relational expression (Fm) indicating a correlation between a change in the environmental state measured by the environmental measurement means and a change in the apparatus state of the exposure apparatus, and the relational expression and the Prediction means (102) for predicting the apparatus state of the exposure apparatus based on the measurement result of the environment measurement means, and maintenance data including the prediction result, the measurement result, and the relational expression are transmitted through the network (N). And a management device (21) for receiving the transmitted maintenance data and recording and managing the apparatus state of the exposure apparatus.

  The environment measuring means (TD1 to TD3) includes the temperature, humidity and pressure inside the exposure apparatus, the temperature, pressure and specific resistance of the liquid used in the exposure apparatus, the temperature, humidity and the outside of the exposure apparatus. It is desirable to measure at least one of the atmospheric pressure and the temperature of the structure part of the exposure apparatus. The management apparatus (21) may determine a maintenance plan for the exposure apparatus based on the maintenance data.

  According to the present invention, it is possible to predict fluctuations in the apparatus state of the substrate processing apparatus by collecting environmental information related to the environment of the substrate processing apparatus.

  Further, when the predicted apparatus state exceeds a predetermined threshold value, warning processing is performed or adjustment processing of the substrate processing apparatus is performed, so that the stability of the apparatus state of the substrate processing apparatus can be improved. effective.

  As a result, the substrate can be processed stably, and a device having the desired performance can be manufactured with a high yield. Further, since the warning process or the adjustment process is performed only when the predicted apparatus state exceeds a predetermined threshold value, the operating rate of the substrate processing apparatus can be improved, and the throughput can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of a substrate processing system including an apparatus state prediction apparatus and an exposure apparatus management system according to an embodiment of the present invention. First, the overall configuration of the substrate processing system will be described with reference to FIG. explain.

  In FIG. 1, 10 indicates a substrate processing factory that performs substrate processing, and 20 indicates a management center that manages substrate processing apparatuses provided in the substrate processing factory. The substrate processing factory 10 is, for example, a factory of a semiconductor manufacturer, and the management center 20 is provided, for example, in one department of the substrate processing apparatus manufacturer. The substrate processing factory 10 and the management center 20 are connected via a network N such as the Internet, a dedicated line, and a public line.

  In the substrate processing factory 10, a plurality of substrate processing apparatuses 11, a host computer 12, a maintenance management server 13, a terminal device 14, and a connection device 15 are provided. These are installed in a clean room where the temperature and humidity are controlled, and are connected to an internal network LN1 such as a LAN (Local Area Network) installed in the substrate processing factory 10. The substrate processing apparatus 11 is a coating process for applying a photosensitive agent such as a photoresist to a substrate such as a wafer, an exposure process for projecting and exposing a mask or reticle pattern image on the substrate coated with the photosensitive agent, And a developing process for developing the exposed substrate.

  Although details will be described later, an air temperature sensor that measures the air temperature, a humidity sensor that measures the humidity, an atmospheric pressure sensor that measures the atmospheric pressure, and structures (hardware, etc.) of each part are provided inside and outside the substrate processing apparatus 11. A sensor for measuring temperature is provided. In the following description, a case where the substrate processing apparatus 11 performs processing on a wafer will be described as an example. However, the present invention can also be applied to a device that performs processing on a glass plate or the like in addition to the wafer. .

  The host computer 12 is a higher-level computer that collectively manages and controls the operations of the plurality of substrate processing apparatuses 11. The maintenance management server 13 collects detection data indicating the detection results of various sensors provided in each substrate processing apparatus 11 or apparatus data indicating the apparatus state of each substrate processing apparatus 11 via the internal network LN1, and obtains in advance. The apparatus state of each substrate processing apparatus 11 is predicted based on a relational expression indicating a correlation between a certain environmental change and an apparatus state change of each substrate processing apparatus 11 and the collected detection data. In addition, the maintenance management server 13 compares the predicted threshold value with a fluctuation threshold value that indicates an allowable value for fluctuations in the device state of the substrate processing apparatus 11 stored in advance.

  As a result of this comparison, if there is a substrate processing apparatus 11 whose apparatus state fluctuation exceeds the threshold value, the maintenance management server 13 issues a warning and an operator (operator) working at the substrate processing factory 10 to that effect. ). Further, the maintenance management server 13 outputs control data for automatically calibrating the apparatus state to the substrate processing apparatus 11 via the internal network LN1 depending on the type of the changed apparatus state. Further, the collected detection data, apparatus data, relational expressions, and prediction results are transmitted as maintenance data to the management center 20 via the network N together with data for specifying the substrate processing factory 10 and the substrate processing apparatus 11. Details of the maintenance management server 13 will be described later.

  The maintenance data is preferably transmitted by e-mail, for example. When transmitting maintenance data by e-mail, if the maintenance data is transmitted in plain text without being encrypted, it may be stolen or tampered, and information such as the performance of the substrate processing apparatus 11 may be obtained. May be known to a third party. Therefore, it is preferable to encrypt the maintenance data and send it by electronic mail. Here, the encryption method is roughly classified into a common key method in which encryption and decryption are performed using the same key, and a public key encryption method in which encryption and decryption are performed using different keys. However, it is preferable to use a public key encryption system from the viewpoint of confidentiality.

  The terminal device 14 is operated by a worker (serviceman) or an operator who performs maintenance of the substrate processing apparatus 11 and is used for inputting various data stored in the maintenance management server 13. For example, a threshold value used in the maintenance management server 13 is input. The connection device 15 is a device for connecting the internal network LN1 laid in the substrate processing factory 10 and the network N, and is a device such as a router. Note that the connection device 15 desirably has a firewall function in order to prevent data indicating the performance and operating status of the substrate processing apparatus 11 handled in the substrate processing factory 10 from leaking to the outside.

  Next, in the management center 20, a management server 21, a plurality of terminal devices 22, and a connection device 23 are provided. These are connected to an internal network LN2 such as a LAN laid in the management center 20. The management server 21 receives the maintenance data sent from the substrate processing factory 10 via the network N, and transmits this maintenance data to a specific person in charge (one or more workers of the management center 20). . The management server 21 stores serviceman data indicating the skill of the serviceman who performs maintenance of the substrate processing apparatus 11 and the workable date, and assigns the serviceman (scheduling) based on the sent maintenance data. ) And other maintenance plans.

  The terminal device 22 is operated by a worker of the management center 20, and for example, performs operations such as input, update, and confirmation of various data stored in the management server 21, or is sent from the management server 21 to each worker. Used to check the contents of maintenance data. The connection form between the terminal device 22 and the internal network LN2 may be either a wired connection or a wireless connection. The connection device 23 is a device for connecting the internal network LN2 laid in the management center 20 and the network N, and is a device such as a router. As with the connection device 15 provided in the substrate processing factory 10, the connection device 23 may have a firewall function in order to prevent various data handled in the management center 20 from leaking to the outside. desirable. An exposure apparatus management system is configured in the substrate processing system with the above-described maintenance management server 13 and management server 21 as main components.

  Next, the substrate processing apparatus 11 provided in the substrate processing factory 10 will be described. FIG. 2 is a top view illustrating a schematic configuration of the substrate processing apparatus 11. Each of the substrate processing apparatuses 11 has the same configuration as that shown in FIG. As shown in FIG. 2, the substrate processing apparatus 11 is provided with a coater / developer section 31 so as to come into contact with a chamber surrounding the exposure apparatus 30 in an in-line manner, and the entire operation of the exposure apparatus 30 and the coater / developer section 31. A control computer 32 for controlling and controlling the above is installed. The control computer 32 is connected to an internal network LN1 installed in the substrate processing factory 10.

  The coater / developer section 31 is provided with a transfer line 33 for transferring the wafer W so as to cross the center. At one end of the transfer line 33, a wafer carrier 34 that stores a large number of unexposed wafers W and a wafer carrier 35 that stores a large number of wafers W that have undergone exposure processing and development processing are disposed. At the other end, a transfer port (not shown) with a shutter on the side surface of the chamber of the exposure apparatus 30 is installed.

  Further, a coater unit 36 is provided along one side surface of the transport line 33 provided in the coater / developer unit 31, and a developer unit 37 is provided along the other side surface. The coater unit 36 includes a resist coater 36a for applying a photoresist to the wafer W from the wafer carrier 34 to the exposure apparatus 30, a pre-baking device 36b including a hot plate for pre-baking the photoresist on the wafer W, and a pre-bake. A cooling device 36c for cooling the wafer W is provided.

  The developer unit 37 performs post-pacing devices 37a and PEB for baking the photoresist on the wafer W after the exposure processing from the exposure device 30 toward the wafer carrier 35, that is, for performing so-called PEB (Post-Exposure Bake). A cooling device 37b for cooling the broken wafer W and a developing device 37c for developing the photoresist on the wafer W are installed. Further, in the present embodiment, a measuring device 38 that measures the shape of a photoresist pattern (resist pattern) formed on the wafer developed by the developing device 37c is installed in-line. The measuring device 38 is for measuring the shape of the resist pattern formed on the wafer W (for example, pattern line width, pattern overlay error, etc.).

  The exposure device 30, the coater unit 36 and the developer unit 37, the measurement device 38, and the control computer 32 are connected by wire or wirelessly, and signals indicating the start or end of each process are transmitted and received. In addition, the device data indicating the device state of these devices and the measurement result by the measuring device 38 are output to the control computer 32 and recorded in a storage device such as a hard disk provided in the control computer 32.

  The exposure apparatus 30 includes a wafer stage 85 that moves two-dimensionally on a wafer base 86 (see FIG. 3), and a wafer W that is an exposure image is held on the wafer stage 85 via a wafer holder 84. In the exposure apparatus 30, a first guide member 39 is disposed so as to substantially extend along the extension line of the central axis of the transport line 33 provided in the coater / developer section 31, and at the end of the first guide member 39. The second guide member 40 is arranged so as to be orthogonal to the upper side.

  The first guide member 39 is provided with a slider 41 configured to be slidable along the first guide member 39, and the slider 41 has a first arm 42 that holds the wafer W so as to be rotatable and vertically movable. Is installed. The second guide member 40 is provided with a second arm 43 configured to be slidable along the second guide member 40 while holding the wafer W. The second guide member 40 extends to the wafer loading position of the wafer stage 85, and the second arm 43 is also provided with a mechanism that slides in a direction perpendicular to the second guide member 40.

  In addition, transfer pins 44 that can be rotated and moved up and down to perform pre-alignment of the wafer W are installed near the position where the first guide member 39 and the second guide member 40 intersect, and the wafer is disposed around the transfer pins 44. A position detection device (not shown) for detecting the positions of notches (notches) on the outer periphery of W and the positions of the two edge portions or the orientation flat formed on the outer periphery of the wafer W is installed. A wafer loader system is constituted by the first guide member 39, the second guide member 40, the slider 41, the first arm 42, the second arm 43, the delivery pin 44, and the like.

  Further, the substrate processing apparatus 11 includes a sensor DT1 such as an air temperature sensor that measures the temperature inside the chamber of the exposure apparatus 30, a humidity sensor that measures humidity, and an atmospheric pressure sensor that measures atmospheric pressure. , The temperature sensor for measuring the temperature in the clean room), the humidity sensor for measuring humidity, the sensor DT2 such as the atmospheric pressure sensor for measuring atmospheric pressure, and the temperature of the structure (hardware) of each part of the substrate processing apparatus 11 Sensor DT3. Detection signals indicating the detection results of these sensors DT1 to DT3 are output to the control computer 32 and recorded in a storage device such as a hard disk provided in the control computer 32 for a certain period. In FIG. 2, the sensor provided in the substrate processing apparatus 11 is represented by the sensor DT1, the sensor provided outside is represented by the sensor DT2, and the sensor for measuring the temperature of the structure is represented by the sensor DT3. These sensors are actually provided in each part in the substrate processing apparatus 11.

  An operation when the substrate processing apparatus 11 having the above-described configuration performs processing on the wafer W will be briefly described. First, a processing start command is output from the host computer 12 in FIG. 1 to the control computer 32 included in the substrate processing apparatus 11 via the internal network LN1. The control computer 32 outputs various control signals to the exposure apparatus 30, the coater unit 36, and the developer unit 37 based on this processing start command. When this control signal is output, one wafer taken out from the wafer carrier 34 is transferred to the resist coater 36a through the transfer line 33 and coated with a photoresist, and the pre-baking device 36b is sequentially applied along the transfer line 33. And it passes to the 1st arm 42 of the exposure apparatus 30 through the cooling apparatus 36c.

  Thereafter, when the slider 41 reaches the vicinity of the transfer pin 44 along the first guide member 39, the first arm 42 rotates, and the wafer W coated with the photoresist is transferred from the first arm 42 onto the transfer pin 44. The position is transferred to the position A, where the center position and the rotation angle are adjusted (pre-alignment) based on the outer shape of the wafer. Thereafter, the wafer W is transferred to the second arm 43 and transferred to the wafer loading position along the second guide member 40, where it is loaded onto the wafer holder 84 on the wafer stage 85. Then, each shot area on the wafer W is exposed through a predetermined device pattern of a reticle as a mask.

  After the exposure processing, the wafer W is transported along the second guide member 40 and the first guide member 39 to the transport line 33 of the coater / developer section 31, and then sequentially along the transport line 33 and the post pacing device 37 a and cooling. It is sent to the developing device 37c via the device 37b. Then, an uneven resist pattern corresponding to the device pattern of the reticle is formed in each shot area of the wafer W developed by the developing device 37c. The wafer W thus developed is inspected by the measuring device 38 for the line width, overlay error and the like of the pattern formed as necessary, and is stored in the wafer carrier 35 along the transfer line 33. After the lithography process is completed, for example, one lot of wafers in the wafer carrier 35 is transferred to a production line for performing a pattern formation process such as etching or ion implantation, a resist stripping process, and the like.

  Next, the exposure apparatus 30 provided in the substrate processing apparatus 11 will be described. FIG. 3 is a view showing a configuration of an exposure apparatus provided in the substrate processing apparatus 11. In this embodiment, a step-and-scan type exposure apparatus will be described as an example. However, a step-and-repeat type exposure apparatus (so-called stepper) may be used in addition to such a type of exposure apparatus. In the following description, the XYZ rectangular coordinate system shown in the figure is set, and the positional relationship of each member will be described with reference to this XYZ rectangular coordinate system. The XYZ orthogonal coordinate system is set such that the Y axis and the Z axis are parallel to the paper surface, and the X axis is set to a direction perpendicular to the paper surface. In the XYZ orthogonal coordinate system in the figure, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z axis is set to the vertically upward direction. A direction along the Y-axis is a scanning (scanning) direction.

In FIG. 3, 51 is an exposure light source, and this exposure light source 51 is an ArF excimer laser light source (wavelength 193 nm) that emits exposure light IL that is a parallel light beam having a substantially rectangular cross section. As this exposure light source 51, in addition to this, for example, an ultrahigh pressure mercury lamp that emits g-line (wavelength 436 nm), i-line (wavelength 365 nm), or KrF excimer laser (wavelength 248 nm), F ₂ laser (wavelength 157 nm), A Kr ₂ laser (wavelength 146 nm), a YAG laser high-frequency generator, or a semiconductor laser high-frequency generator can be used.

  Exposure light IL (exposure beam) consisting of an ultraviolet pulse with a wavelength of 193 nm from the exposure light source 51 passes through a beam matching unit (BMU) 52 and enters a variable dimmer 53 as an optical attenuator. An exposure control unit 73 for controlling the exposure amount of the photoresist on the wafer W controls the start and stop of light emission of the exposure light source 51 and the output (oscillation frequency, pulse energy), and in the variable dimmer 53. The dimming rate is adjusted stepwise or continuously.

  The exposure light IL that has passed through the variable dimmer 53 enters a first fly-eye lens 56 as a first-stage optical integrator (a homogenizer or a homogenizer) through a beam shaping system 55 including lens systems 54a and 54b. To do. The exposure light IL emitted from the first fly-eye lens 56 passes through the first lens system 57a, the optical path bending mirror 58, and the second lens system 57b, and the second fly as a second-stage optical integrator. The light enters the eye lens 59.

  On the exit surface of the second fly-eye lens 59, that is, the optical Fourier transform surface (pupil surface of the illumination system) with respect to the pattern surface of the reticle R, an aperture stop plate 60 is rotatably arranged by a drive motor 60a. The aperture stop plate 60 includes a circular aperture stop for normal illumination, an aperture stop for annular illumination, an aperture stop for modified illumination comprising a plurality of (for example, four poles) eccentric small apertures, and a small coherence factor (σ A small circular aperture stop for (value) is arranged to be switchable. A main control system 74 that performs overall control of the overall operation of the exposure apparatus 30 rotates the aperture stop plate 60 via the drive motor 60a to set illumination conditions.

  The exposure light IL that is emitted from the second fly-eye lens 59 and passes through any one of the aperture stops formed on the aperture stop plate 60 is incident on the beam splitter 61 that has high transmittance and low reflectivity. The exposure light reflected by the beam splitter 61 enters an integrator sensor 72 composed of a photoelectric detector via a condensing lens 71, and a detection signal from the integrator sensor 72 is supplied to an exposure control unit 73. The relationship between the detection signal of the integrator sensor 72 and the illuminance of the exposure light IL on the wafer W is measured in advance with high accuracy and stored in the memory in the exposure control unit 73. The exposure control unit 73 is configured to monitor the illuminance (average value) of the exposure light IL with respect to the wafer W and its integrated value indirectly from the detection signal of the integrator sensor 72.

  The exposure light IL that has passed through the beam splitter 61 sequentially enters the fixed blind (fixed illumination field stop) 64 and the movable blind (movable illumination field stop) 65 through the lens systems 62 and 63 along the optical axis IAX. The latter movable blind 65 is installed on a conjugate plane with respect to the reticle plane, and the former fixed blind 64 is arranged on a plane defocused by a predetermined amount from the conjugate plane. The fixed blind 64 is an opening arranged so as to extend in a straight slit shape or a rectangular shape (hereinafter collectively referred to as a “slit shape”) in a direction orthogonal to the scanning exposure direction at the center in the circular field of the projection optical system PL. Part.

  The exposure light IL that has passed through the fixed blind 64 and the movable blind 65 passes through a mirror 66 for bending an optical path, an imaging lens system 67, a condenser lens 68, and a main condenser lens system 69. The illumination area (illumination field area) IA on the pattern surface (lower surface) is illuminated. The BMU 52 to the main condenser lens 69 constitute an illumination optical system IS. Under the exposure light IL, the image of the circuit pattern in the illumination area IA of the reticle R is projected at a predetermined projection magnification β (β is, for example, 1/4 or 1/5) through the bilateral telecentric projection optical system PL. Then, the image is transferred to the slit-shaped exposure region of the photoresist layer on the wafer W arranged on the imaging surface of the projection optical system PL.

  The reticle R is attracted and held on a reticle stage 81, and the reticle stage 81 is mounted on the reticle base 82 so as to move at a constant speed in the Y direction and to be inclined in the X direction, the Y direction, and the rotation direction. . The two-dimensional position and rotation angle of reticle stage 81 (reticle R) are measured in real time by a laser interferometer in drive control unit 83. Based on this measurement result and control information from the main control system 74, the drive motor (linear motor, voice coil motor, etc.) in the drive control unit 83 controls the scanning speed and position of the reticle stage 81.

  On the other hand, the wafer W is sucked and held on the wafer stage 85 via the wafer holder 84, and the wafer stage 85 moves two-dimensionally on the wafer base 86 along the XY plane parallel to the image plane of the projection optical system PL. That is, the wafer stage 85 moves on the wafer base 86 in the Y direction at a constant speed and also moves stepwise in the X direction and the Y direction. Further, the wafer stage 85 incorporates a Z leveling mechanism for controlling the position of the wafer W in the Z direction (focus position) and the tilt angles around the X axis and the Y axis.

  The position of the wafer stage 85 in the X and Y directions and the rotation angles around the X, Y, and Z axes are measured in real time by a laser interferometer in the drive control unit 87. Based on this measurement result and control information from the main control system 74, a drive motor (such as a linear motor) in the drive control unit 87 controls the scanning speed and position of the wafer stage 85. Further, an illuminance sensor 88 that detects the illuminance (light quantity) of the exposure light IL irradiated to the exposure area on the wafer W via the projection optical system PL is fixed to one end on the wafer stage 85.

  The illuminance sensor 88 has a housing in which, for example, a pinhole sensor is formed, and is a sensor in which a light receiving surface of a light receiving element is disposed at a position where the pinhole is formed, and exposure light IL incident through the pinhole. The illuminance (light quantity) is detected. A detection signal from the illuminance sensor 88 is supplied to the exposure control unit 73. By moving the illuminance sensor 88 within the exposure area while the exposure light IL is being irradiated on the wafer stage 85, the illuminance unevenness (light amount unevenness) and the integrated light amount unevenness of the exposure light IL can be measured. Further, by detecting the illuminance of the exposure light IL while moving the illuminance sensor 88 in the Z direction, the image plane position (best focus position) of the projection optical system PL can be obtained. The measurement of the illuminance, the illuminance unevenness, the accumulated light amount unevenness, and the measurement of the best focus position using the illuminance sensor 88 and the measurement of the best focus position are performed regularly or irregularly.

  Further, a reference member 89 that determines the reference position of the wafer stage 85 is provided at one end on the wafer stage 85. The reference member 89 is used to measure the relative position and baseline amount of the reticle R with respect to the coordinate system of the wafer stage 85. Here, the baseline amount refers to, for example, the distance between the center position of the projected image of the pattern formed on the reticle R by the projection optical system PL and the center of the measurement visual field of the wafer alignment sensor 92 described later. The reference member 89 has, as reference marks, for example, a slit pattern formed of five light-transmitting L-shaped patterns and two sets of reference patterns formed of light-reflective chrome (the duty ratio is 1: 1). And are provided.

  Further, on the side surface of the projection optical system PL, a projection optical system 90a that projects a slit image obliquely onto a plurality of measurement points on the surface (test surface) of the wafer W, and reflected light from the test surface is received. A multi-point autofocus sensor including a light receiving optical system 90b that generates a focus signal corresponding to the focus positions of the plurality of measurement points is also provided, and these focus signals are provided to the main control system 74. Have been supplied. The focus error, which is the positional deviation of the wafer W with respect to the image plane of the projection optical system PL, is obtained from the difference between the best focus position measured using the illuminance sensor 88 and the image plane position measured by the autofocus sensor. .

  That is, in the autofocus sensor, the detection result obtained when the image plane of the projection optical system PL and the surface of the wafer W coincide with each other is set to zero. Therefore, when the position of the image plane of the projection optical system PL, the optical component provided in the autofocus sensor, or the mechanical mechanism that holds this component is affected by environmental fluctuations, the surface of the wafer W is actually projected. Even if it is arranged on the image plane of the optical system PL, the detection result of the autofocus sensor does not coincide with the zero point, and a measurement error occurs. Since the position of the wafer W in the Z direction is controlled based on the detection result of the autofocus sensor, the measurement error of the autofocus sensor causes a focus error during exposure. Accordingly, the focus error can be obtained by obtaining the difference between the best focus position measured using the illuminance sensor 88 and the image plane position measured by the autofocus sensor.

  Further, when performing scanning exposure, it is necessary to align the reticle R and the wafer W in advance. Therefore, a VRA (Visual Reticle Alignment) type reticle alignment sensor 91 that measures the position of the alignment mark (reticle mark) of the reticle R is provided above the reticle stage 81. Further, in order to measure the position of the alignment mark (wafer mark) on the wafer W, a wafer alignment sensor 92 of an image processing method (FIA method: Full Image Alignment method) is provided on the side surface of the projection optical system PL. is set up. The wafer alignment sensor 92 illuminates an alignment mark on the wafer W with illumination light of a relatively wide wavelength range from, for example, a halogen lamp and picks up the image with an image pickup device such as a CCD (Charge Coupled Device). is there. The image signal obtained by the wafer alignment sensor 92 is supplied to the main control system 74, subjected to image processing, and position information is measured.

  The main control system 74 is provided in the control computer 32 shown in FIG. 2, and reads various exposure conditions for scanning and exposing the photoresist in each shot area on the wafer W with an appropriate exposure amount from the exposure data file. The optimum exposure sequence is executed in cooperation with the exposure control unit 73. Prior to the exposure process, the main control system 74 is formed on the wafer W using the wafer alignment sensor 92 after adjusting the position and orientation of the wafer W in the optical axis AX direction based on the detection result of the autofocus sensor. Position information of a predetermined number (3 to 9) of alignment marks is measured from the alignment marks. Then, a statistical calculation called an EGA (enhanced global alignment) calculation is performed using the measured position information to obtain an array of all shot areas set on the wafer W.

  When the exposure process is started, the main control system 74 sends various information such as the movement position, movement speed, movement acceleration, and position offset of the reticle stage 81 and the wafer stage 85 to the drive control units 83 and 87. Thereby, acceleration of reticle stage 81 and wafer stage 85 is started. The main control system 74 also issues a scanning exposure start command to the exposure control unit 73. When the acceleration of the reticle stage 81 and the wafer stage 85 is completed and the speed becomes constant, the exposure control unit 73 starts to emit light from the exposure light source 51, and the illuminance (unit) of the exposure light IL with respect to the wafer W via the integrator sensor 72. The integral value of the sum of pulse energy per hour) is calculated. The integrated value is reset to 0 at the start of scanning exposure.

  During scanning exposure, the reticle R is scanned via the reticle stage 81 in the + Y direction (or -Y direction) at the speed Vr with respect to the illumination area IA of the exposure light IL via the wafer stage 85. Then, the wafer W is scanned in the −Y direction (or + Y direction) at a speed α · Vr (α is the projection magnification from the reticle R to the wafer W) with respect to the exposure area of the pattern image of the reticle R. The movement direction of the reticle R and the wafer W is opposite because the projection optical system PL of this example performs reverse projection. Even during scanning exposure, the posture control of the wafer W is performed based on the detection result of the autofocus sensor.

  During the scanning exposure, the exposure control unit 73 sequentially calculates the integrated value of the illuminance of the exposure light IL, and according to this result, an appropriate exposure amount is obtained at each point of the photoresist on the wafer W after the scanning exposure. As obtained, the output (oscillation frequency and pulse energy) of the exposure light source 51 and the dimming rate of the variable dimmer 53 are controlled. Then, at the end of the scanning exposure to the shot area, the light emission of the exposure light source 51 is stopped. By repeating this operation, an exposure process is performed on a plurality of shot areas set on the wafer W.

  The main control system 74 is provided with a storage device such as a semiconductor memory or a hard disk, and data indicating the detection result of the integrator sensor 72, illuminance obtained by measurement using the illuminance sensor 88, illuminance unevenness, and integration. Data indicating unevenness of light quantity, data indicating synchronization error between reticle stage 81 and wafer stage 85, data indicating positional deviation amount (focus error) of wafer W with respect to the image plane of projection optical system PL obtained by an autofocus sensor, etc. Are stored as apparatus data for a certain period. When there is a data transmission request from the maintenance management server 13 shown in FIG. 1, the main control system 74 reads the temporarily stored device data and outputs it to the maintenance management server 13 via the internal network LN1.

  Next, the maintenance management server 13 provided in the substrate processing factory 10 in FIG. 1 will be described. FIG. 4 is a functional block diagram showing functions provided in the maintenance management server 13. As shown in FIG. 4, the maintenance management server 13 includes a data collection unit 101, an apparatus state prediction unit 102, a comparison unit 103, a control command output unit 104, a display unit 105, a mail transmission unit 106, a relational expression update unit 107, and a storage. The unit 108 is configured to be included.

  The storage unit 108 stores a relational expression Fm and a fluctuation threshold Th as shown in FIG. The relational expression Fm is a relational expression showing the correlation between the environmental change and the apparatus state change of each substrate processing apparatus 11. The relational expression Fm uses detection data obtained from various sensors (sensors DT1 to DT3 typically shown in FIG. 2) provided in the substrate processing apparatus 11 as explanatory variables, and the apparatus state of the substrate processing apparatus 11 as an objective variable. Multiple regression equation. In the present embodiment, when the apparatus state of the substrate processing apparatus 11 as the objective variable is a positional deviation (focus error) of the wafer W with respect to the image plane of the projection optical system PL provided in the exposure apparatus 30 shown in FIG. Will be described as an example.

Here, when n (n is a natural number) explanatory variables are X _{1 to} X _n and the objective variable is Y, the multiple regression equation is expressed by the following equation (1).

In the above equation (1), β ₀ is a constant term, and β _{1 to} β _n are regression coefficients. What is stored as the relational expression Fm is the values of the constant term β ₀ and the regression coefficients β _{1 to} β _n shown in (1) above. A method for obtaining the constant term β ₀ and the regression coefficients β _{1 to} β _n will be described later. In the present embodiment, since detection data obtained from various sensors provided in the substrate processing apparatus 11 is an explanatory variable, n in the above equation (1) is a number equal to or less than the number of sensors.

  The fluctuation threshold Th is an allowable value for fluctuations in the apparatus state of the substrate processing apparatus 11, and is input by a service person from the terminal apparatus 14 provided in the substrate processing factory 10 shown in FIG. Is done. In the present embodiment, the case where the apparatus state of the substrate processing apparatus 11 as the objective variable is a focus error is described, and therefore a numerical value indicating an allowable focus fluctuation amount is stored as the fluctuation threshold Th. The allowable focus fluctuation amount can take various values depending on the depth of focus of the projection optical system PL, the line width of the pattern to be exposed, the resist process, and the like, but is approximately a value of about several tens of nm to several μm.

  A data collection unit 101 provided in the maintenance management server 13 sends a detection request of various sensors or a transmission request of apparatus data indicating an apparatus state to each of the substrate processing apparatuses 11 provided in the substrate processing factory 10. The detection data or device data sent in response to the transmission request is collected and stored for a certain period. The transmission request for detection data and device data is made every predetermined period (for example, several hours, one day, or several days). Note that the detection data of various sensors provided in the substrate processing apparatus 11 and the apparatus data indicating the apparatus state are recorded in the control computer 32 shown in FIG. 2 (main control system 74 shown in FIG. 3). Data for several months) may be collected at once.

  The apparatus state prediction unit 102 predicts a focus error which is one of the apparatus states using the detection data collected by the data collection unit 101 and the relational expression Fm stored in the storage unit 108. Specifically, the predicted value Y ^ of the focus error is obtained using the following equation (2). In the present specification, for the sake of notation, a symbol with a hat symbol “^” added above the symbol “Y” is displayed as “Y ^”.

Since the constant term β ₀ and the regression coefficients β _{1 to} β _n in the equation (2) are stored in the storage unit 108 as the relational expression Fm, the detection data is used as the explanatory variables X _{1 to} X _n (2). By substituting it into the equation, the predicted value Y ^ of the focus error can be obtained.

  The comparison unit 103 compares the prediction value (focus error prediction value Y ^) output from the apparatus state prediction unit 102 with the fluctuation threshold Th stored in the storage unit 108, and the prediction value Y ^ is the fluctuation threshold. It is determined whether or not Th is exceeded. When the comparison unit 103 determines that the predicted value Y ^ of the focus error exceeds the variation threshold Th, the control command output unit 104 adjusts the apparatus state with respect to the substrate processing apparatus 11 that has made such determination. The control command to be output is output via the internal network LN1. Specifically, this control command is a command for executing calibration of the autofocus sensor in order to reduce the focus error.

  The display unit 105 includes a display device such as a CRT (Cathode Ray Tube) or a liquid crystal display element. Based on the determination result of the comparison unit 103, a warning such as highlighting the prediction result of the device state prediction unit 102 is displayed. Display and notify the operator to that effect. The mail transmission unit 106 notifies the management center 20 of maintenance data including the prediction result of the apparatus state prediction unit 102 together with information for specifying the substrate processing factory 10 and the substrate processing apparatus 11 based on the determination result of the comparison unit 103. Create and send.

  The substrate processing apparatus 11 itself can reduce the focus error, which is one of the apparatus states, by calibrating the autofocus sensor. However, depending on the type of the apparatus state, maintenance by a serviceman may be required. is there. In such a case, the mail transmission unit 106 transmits the maintenance data in a mail format, so that a service person can deal with it. When the correlation between the environmental change and the apparatus state change changes, the relational expression update unit 107 periodically checks the correlation between the two and updates the relational expression Fm stored in the storage unit 108. .

Here, a method for obtaining the constant term β ₀ and the regression coefficients β _{1 to} β _n in the regression equation shown in the equation (1) will be described. First, detection data of various sensors provided in the substrate processing apparatus 11 and a measurement result of a focus error when the detection data is obtained are obtained over several months. Next, a plurality of relational expressions are obtained by substituting the obtained detection data and focus error measurement results into the above equation (1) as explanatory variables X _{1 to} X _n and objective variable Y, respectively.

If there are k (k is a natural number) pairs of detection data and focus error measurement results, k relational expressions are obtained. Of these k relational expressions, the i-th expression (i is an integer satisfying 1 ≦ i ≦ k) is represented by the following expression (3). In the following equation (3), for example, the term X _i1 represents the i-th explanatory variable X ₁ and represents i-th detection data obtained by a certain sensor.

The constant term β ₀ and the regression coefficients β _{1 to} β _n have the smallest residual as shown in the following formula (4) using the least square method with respect to the relational formula shown in the above formula (3). It is obtained by obtaining a combination of the constant term β ₀ and the regression coefficients β _{1 to} β _n .

Further, the correlation between the detection data indicating the change in the environment and the focus error which is one of the apparatus states of the substrate processing apparatus 11 can be investigated by performing multiple regression analysis. In this multiple regression analysis, the total contribution rate (square of multiple correlation coefficient) R ² , partial contribution rate (square of multiple correlation coefficient adjusted for degrees of freedom) R ^{2 *} , F value, and risk factor are Used. The total contribution rate R ² is expressed by using the total sum of squares St and the residual sum of squares Se as shown in the following equation (5), and can be explained by regression among the total fluctuations of the objective variable Y. It shows the ratio. In the following equation (5), a symbol with a bar symbol “￣” added above the symbol “Y _i ” _represents an average value of the objective variables Y _{1 to} Y _k .

Further, when the number of explanatory variables X _{1 to} X _n is increased, the contribution rate shows a change that approaches the value “1” as the number increases. I don't know if it is. The partial contribution rate R ^{2 *} indicates the contribution rate of each of the explanatory variables X _{1 to} X _n , and as shown in the following equation (6), the overall average square MSt and the residual average square MSe are used. It is expressed as In the following equation (6), n is the number of samples, p is the number of explanatory variables and indicates the degree of freedom of regression, and (n−p−1) indicates the degree of freedom of residual. .

  The F value is used to determine whether or not a correlation between detection data indicating a change in environment and a focus error, which is one of the apparatus states of the substrate processing apparatus 11, is recognized. This F value is expressed using the mean square MSe of the residual and the mean square MSr of the regression as shown in the following equation (7).

  FIG. 5 is a diagram illustrating an example of a result of the multiple regression analysis. In FIG. 5, “sensor number” is a number assigned to various sensors provided in the substrate processing apparatus 11. These sensors include, for example, sensors for measuring the temperature of the clean room, the humidity in the chamber of the exposure apparatus 30, the atmospheric pressure in the chamber, and the like. In the example shown in FIG. 5, when the multiple regression analysis is performed, the detection data of the 16 sensors assigned the sensor numbers X1 to X16 are used, but the detection results of the sensors of the sensor numbers X7 and X13 are the regressions. Excluded from explanatory variables because they are not useful for analysis.

  As shown in FIG. 5, the partial contribution rate, the overall contribution rate, the F value, and the risk factor (significance probability) that the environmental change detected by each sensor contributes to the change in the focus error, which is the objective variable Y, are obtained. . In FIG. 5, the items are rearranged in descending order based on the overall contribution rate. Focusing on the partial contribution rate, it can be seen that the partial contribution rate of the environmental fluctuation detected by the sensor number X15 having the largest F value is significantly larger than the others, and the values are substantially smaller in the order of rearrangement.

  The relational expression updating unit 107 creates the relational expression Fm using only the detection data of the sensor with the sensor number having a large F value from the obtained multiple regression analysis result, or updates the relational expression Fm. In the example shown in FIG. 5, for example, only the detection data of ten sensors with sensor numbers X15, X1, X16, X6, X8, X11, X10, X9, X14, and X5 having large F values are used. However, when there are a plurality of detection data (detection data with high correlation) having almost the same change with time, only one of these detection data is used. In the example shown in FIG. 5, the correlation between the detection data obtained from the sensors assigned the sensor numbers X6 and X8 is high, and the correlation between the detection data obtained from the sensors assigned the sensor numbers X10 and X9 is high. The detection data of the sensors assigned the sensor numbers X8 and X9 are used except for the detection data of the sensors assigned the sensor numbers X6 and X10.

In this way, only the detection data of the eight sensors with sensor numbers X1, X5, X8, X9, X11, X14, X15, and X16 having large F values useful for obtaining the focus error are used. Formula Fm is created or relational expression Fm is updated. To create and update the relational expression Fm, first, the detection data of the eight sensors and the measurement result of the focus error are substituted into the above equation (1) as the explanatory variables X _{1 to} X _n and the objective variable Y, respectively (3 ) Get the formula. Next, with respect to the relational expression shown in the expression (3), a constant term β ₀ and a regression coefficient β ₁ that minimize the residual as shown in the above expression (4) using the least square method. obtained by calculating the combination of ~β _n.

It is to be noted that the detection data obtained by performing the multiple regression analysis shown in FIG. 5 is obtained using only the detection data of the eight sensors assigned sensor numbers X1, X5, X8, X9, X11, X14, X15, and X16. overall contribution ^{R 2} has, 0.8224 was obtained. Therefore, it can be seen that the relational expression Fm created for predicting the focus fluctuation from the detection data of various sensors is useful for the prediction.

  Next, the operation of this substrate processing system will be described. FIG. 6 is a flowchart showing the operation of the maintenance management server 13. In the following description, the relational expression Fm indicating the correlation between the detection data of the sensors DT1 to DT3 indicating the environmental change and the focus error which is one of the apparatus states of the substrate processing apparatus 11 has already been obtained. And stored in the storage unit 108 of the maintenance management server 13.

  A control computer 32 (including a main control system 74 provided in the exposure apparatus 30) provided in the substrate processing apparatus 11 periodically samples detection signals output from the sensors DT1 to DT3 provided in the substrate processing apparatus 11. And stored as detection data in a storage device (not shown). When the detection data collection time comes, the data collection unit 101 of the maintenance management server 13 sends a detection data transmission request to each substrate processing apparatus 11. This transmission request is transmitted to each substrate processing apparatus 11 via the network LN1.

Based on this transmission request, the control computer 32 (main control system 74) provided in each substrate processing apparatus 11 reads the detection data stored in a storage device (not shown), and the maintenance management server 13 via the internal network LN1. Send to. In this way, the apparatus data collection unit 101 collects detection data from each of the substrate processing apparatuses 11 (step S1). When the detection data is collected, the collected detection data is output to the device state prediction unit 102. The apparatus state prediction unit 102 predicts a focus error which is one of the apparatus states for each substrate processing apparatus 11 by using the detection data collected by the data collection unit 101 and the relational expression Fm stored in the storage unit 108 ( Step S2). Specifically, the collected detection data is substituted as the explanatory variables X _{1 to} X _n into the above-described equation (2) to obtain the predicted value ＾ (focus error predicted value).

  The predicted value y ^ for each substrate processing apparatus 11 obtained by the apparatus state prediction unit 102 is output to the comparison unit 103, and is compared with the variation threshold Th in the comparison unit 103, and the prediction value y ^ becomes the variation threshold Th. It is determined whether or not it exceeds (step S3). If the predicted values y ^ for all the substrate processing apparatuses 11 do not exceed the fluctuation threshold Th, the determination result is “NO”, and the current process ends.

  On the other hand, if there is a predicted value y ^ that exceeds the fluctuation threshold Th among the predicted values y ^ for each substrate processing apparatus 11, the determination result is "YES", and information indicating that and the substrate Device information for specifying the processing device 11 is output from the comparison unit 104 to the control command output unit 104. When these pieces of information are input, the control command output unit 104 outputs a control command that causes the substrate processing apparatus 11 specified by the apparatus information to adjust the apparatus state (focus error) through the internal network LN1 (step). S4).

  When a control command is sent, the control computer 32 (main control system 74) provided in the substrate processing apparatus 11 activates the calibration function of the autofocus sensor to adjust the focus error. I do. Thus, the apparatus state of the substrate processing apparatus 11 is predicted, and the autofocus sensor is calibrated based on the prediction result.

  FIG. 7 is a diagram illustrating an example of the actually measured value and the predicted value of the focus error. In the graph shown in FIG. 7, the horizontal axis represents time, and the vertical axis represents focus error. The time on the horizontal axis is a scale of several months. In FIG. 7, the actual measurement value and the prediction value are respectively shown as a line graph in which the actual measurement value is connected by a solid line and the prediction value is connected by a dotted line. Referring to FIG. 7, it can be seen that the method of predicting the apparatus state from the environmental fluctuation according to the present invention is effective because the predicted value substantially coincides with the actually measured value. In the above embodiment, the focus error is adjusted by performing autofocus calibration. However, if the prediction accuracy is high, the focus error may be directly adjusted based on the predicted value without performing calibration. .

  Returning to FIG. 6, the description of the operation of the maintenance management server 13 will be continued. The data collection unit 101 requests the substrate processing apparatus 11 to transmit the calibration result (apparatus data) of the autofocus sensor. In response to this transmission request, the substrate processing apparatus 11 transmits apparatus data to the maintenance management server 13 via the internal network LN1. In this way, the apparatus data collection unit 101 collects apparatus data from the substrate processing apparatus 11 (step S5). The collected device data is sent to the relational expression updating unit 107 together with the previously collected detection data, and the above-described multiple regression analysis is performed based on the latest detection data and device data (step S6). As a result, when it is determined that the correlation between the environmental change and the apparatus state change has changed, the relational expression update unit 107 updates the relational expression Fm, and the new relational expression Fm is stored in the storage unit 108. (Step S8).

  Through the above processing, the focus error of the exposure apparatus 30 provided in the substrate processing apparatus 11 can be kept below a certain level, and the stability of the apparatus state can be improved. As a result, a fine pattern can be stably formed on the wafer, and a device having the desired performance can be manufactured with a high yield. In addition, since autofocus calibration is performed only when necessary (when the focus error exceeds the threshold value), the calibration that was previously performed at the beginning of the lot must be largely omitted. In addition, throughput (the number of wafers W that can be processed per unit time) can be improved.

  In the above description, the focus error that can be automatically adjusted by calibration as an apparatus state has been described as an example. However, when an operator operation is required to improve the apparatus state In step S4, information indicating that the predicted value y ^ exceeds the fluctuation threshold Th is output from the comparison unit 103, and the prediction result of the device state prediction unit 102 is output to the display unit 105. For example, a warning display such as highlighting the prediction result of the display state prediction unit 102 is performed.

  If the predicted device state requires maintenance by a service person to improve the device state, the predicted value y ^ exceeds the fluctuation threshold Th in step S4. Is output from the comparison unit 103, and the prediction result of the apparatus state prediction unit 102 is output to the mail transmission unit 106. The network N is used as maintenance data together with data for specifying the substrate processing factory 10 and the substrate processing apparatus 11. To the management center 20 via e-mail. A service person of the management center 20 performs maintenance work on the substrate processing apparatus 11 specified by the data included in the maintenance data according to the contents of the maintenance data, and improves the apparatus state.

  In the above-described embodiment, the sequence in which the relational expression Fm is updated when the predicted value y ^ exceeds the fluctuation threshold Th in step S3 has been described. However, when the predicted value y ^ does not exceed the fluctuation threshold Th. Even so, it is desirable to periodically determine whether the relational expression needs to be updated. In the exposure apparatus 30, measurement of a focus error or the like is performed regularly (for example, once a day). The maintenance management server 13 may execute steps S1 and S5 to S8 simultaneously with the above measurement to confirm whether the relational expression Fm needs to be updated, and update the relational expression Fm as necessary. As a result, it is possible to always calculate the predicted value y ^ with the highly reliable relational expression Fm, and to improve the prediction accuracy.

  Furthermore, in the above embodiment, the maintenance management server 13 connected to the internal network LN1 collects detection data from each substrate processing apparatus 11 and predicts the apparatus state of the substrate processing apparatus 11. However, the function of the maintenance management server 13 is provided in the control computer 32 of each substrate processing apparatus 11, and the apparatus state is adjusted when the apparatus state is predicted by the substrate processing apparatus 11 alone and the apparatus state deteriorates. May be.

  In the embodiment described above, the focus variation is exemplified as an example of the apparatus state, and the case where the focus variation is predicted and adjusted is described as an example. However, in addition to the focus error, the apparatus state to be predicted is an EGA based on the exposure amount of exposure light used in the exposure apparatus 30, the focus error of the wafer alignment sensor 92, the baseline amount, and the measurement result of the wafer alignment sensor 92. There may be various factors such as the magnification of the wafer W and the magnification of the shot area obtained by performing the calculation, and the collapse of the telecentricity of the reticle alignment sensor 81 and the wafer alignment sensor 92.

Moreover, in the said embodiment, the case where the sensor which measures temperature, humidity, and atmospheric pressure was provided in the inside and the exterior of the substrate processing apparatus 11 was explained as an example. However, in addition to these, a sensor that detects various impurity concentrations in the air may be provided, and the detection result of this sensor may be used as one or more of the explanatory variables X _{1 to} X _n . Furthermore, in the case of an immersion type exposure apparatus disclosed in International Publication No. WO 99/49504 pamphlet, the liquid temperature, liquid pressure, specific resistance of the liquid supplied to the space between the projection optical system and the wafer, In addition, sensors that respectively detect the impurity concentration and pH in the liquid may be provided, and the detection results of these sensors may be used as one or more of the explanatory variables X _{1 to} X _n .

  Next, manufacture of a device according to an embodiment of the present invention will be described. FIG. 8 is a flowchart showing an example of a manufacturing process of a device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.). As shown in FIG. 8, first, in step S10 (design step), device functional design (for example, circuit design of a semiconductor device) is performed, and pattern design for realizing the function is performed. Subsequently, in step S11 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step S12 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

  Next, in step S13 (wafer process step), using the mask and wafer prepared in steps S10 to S12, the exposure process and the exposure process for transferring the pattern formed on the mask by lithography technology onto the wafer are completed. For example, a development process for developing the wafer and a substrate process for performing an etching process are performed on the wafer after the development process to form an actual circuit or the like on the wafer. Next, in step S14 (assembly step), the wafer processed in step S13 is formed into chips. This step S14 includes processes such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. Finally, in step S15 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step S14 are performed. After these steps, the device is completed and shipped.

  The embodiment described above is described in order to facilitate understanding of the present invention, and is not described in order to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, the function of each block of the maintenance management server 13 shown in FIG. 4 can be configured by hardware, and can also be realized by software. When realized by software, the hardware configuration of the maintenance management server 13 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a communication interface, an optical disk, a magnetic disk, and a magneto-optical disk. This is realized by causing the maintenance management server 13 to read a program for executing the above-described processing and executing the program.

  Further, in the above embodiment, when the control function is provided in the control computer 32 (main control system 74) and a control command is received from the maintenance management server 13, the calibration function is activated to perform calibration. It was. However, the maintenance management server 13 may be provided with a function of controlling the substrate processing apparatus 11, and the maintenance management server 13 may control the substrate processing apparatus 11 to perform processing such as calibration.

  In the above embodiment, the exposure apparatus 30 uses laser light emitted from an ArF excimer laser or the like as the exposure light IL. However, a soft X-ray region generated from a laser plasma light source or SOR, for example, a wavelength of 13.4 nm. Alternatively, 11.5 nm EUV (Extreme Ultra Violet) light may be used. Furthermore, you may use charged particle beams, such as an electron beam or an ion beam. Further, the projection optical system PL may use any of a reflection optical system, a refractive optical system, and a catadioptric optical system.

  In addition, a single wavelength laser in the infrared or visible range oscillated from a DFB semiconductor laser or fiber laser is amplified by a fiber amplifier doped with, for example, erbium (or both erbium and yttrium), and a nonlinear optical crystal is used. Alternatively, harmonics converted to ultraviolet light may be used.

  Furthermore, the substrate processing apparatus 11 transfers not only an exposure apparatus for transferring a device pattern used for manufacturing a semiconductor element onto the wafer W but also a device pattern used for manufacturing a display including a liquid crystal display element on a glass plate. An exposure apparatus used for manufacturing a thin film magnetic head, an exposure apparatus for transferring a device pattern used for manufacturing a thin film magnetic head onto a ceramic exposure light, an exposure device used for manufacturing an imaging device (CCD, etc.), a micromachine, and a DNA chip. Also good.

It is a block diagram showing the whole substrate processing system composition provided with the device state prediction device concerning the embodiment of the present invention. It is a top view which shows schematic structure of a substrate processing apparatus. It is a figure which shows the structure of the exposure apparatus with which a substrate processing apparatus is provided. It is a functional block diagram which shows the function provided in a maintenance management server. It is a figure which shows an example of the result of a multiple regression analysis. It is a flowchart which shows operation | movement of a maintenance management server. It is a figure which shows an example of the actual value and prediction value of a focus error. It is a flowchart which shows an example of the manufacturing process of a device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Substrate processing apparatus 13 ... Maintenance management server (apparatus state prediction apparatus)
30 ... Exposure apparatus (substrate processing apparatus)
32. Control computer (control means)
74 ... Main control system (storage means, prediction means, execution means)
101 ... Data collection unit (environmental information collection means)
102: Device state prediction unit (prediction means)
104 ... Control command output unit (adjustment means)
105 ... Display section (warning means)
106: Mail sending section (warning means)
107 ... Relational expression update unit (update means)
108: Storage section (storage means)
DT1 ... sensor (environmental information collecting means, internal environment detecting means, environment measuring means)
DT2 ... sensor (environmental information collection means, external environment detection means, environment measurement means)
DT3 ... sensor (environmental information collecting means, structure temperature detecting means, environmental measuring means)
Fm ... Relational expression LN1 ... Internal network (network)
R ... reticle (mask)
Th: Dynamic threshold (threshold)
W ... Wafer (substrate)

Claims (19)

An apparatus state prediction apparatus for predicting an apparatus state of a substrate processing apparatus for processing a substrate,
Environmental information collecting means for collecting environmental information about the environment of the substrate processing apparatus;
Storage means for storing a relational expression indicating a correlation between the environmental change and the apparatus state change of the substrate processing apparatus;
Prediction means for predicting an apparatus state of the substrate processing apparatus based on the relational expression and the environment information collected by the environment information collection means;
A comparison means for comparing the prediction result of the prediction means with a predetermined threshold;
An apparatus state prediction apparatus comprising: an execution unit that executes predetermined processing based on a comparison result of the comparison unit.   The apparatus state prediction apparatus according to claim 1, wherein the relational expression is a regression expression in which the environment is an explanatory variable and the apparatus state is an objective variable. Apparatus information collecting means for collecting apparatus information relating to the apparatus state of the substrate processing apparatus;
The apparatus state prediction apparatus according to claim 1, further comprising: an update unit that updates the relational expression stored in the storage unit based on the environment information and the apparatus information.   The said execution means is provided with the transmission means which performs a transmission process with respect to the management apparatus which manages the said substrate processing apparatus with the maintenance data containing the said prediction result, The Claim 1 characterized by the above-mentioned. The apparatus state prediction apparatus as described in.   The apparatus state prediction apparatus according to claim 1, wherein the execution unit includes a warning unit that executes a warning process when the prediction result exceeds the threshold value.   The said execution means is provided with the adjustment means which performs the adjustment process of the apparatus state of the said substrate processing apparatus when the said prediction result exceeds the said threshold value, The any one of Claims 1-5 characterized by the above-mentioned. The apparatus state prediction apparatus of description.   The environmental information collecting means detects an internal environment for detecting at least one of a temperature, a humidity, and an atmospheric pressure inside the substrate processing apparatus or a temperature, a pressure, and a specific resistance of a liquid used in the substrate processing apparatus. Means for detecting at least one of temperature, humidity and pressure outside the substrate processing apparatus, and structure temperature detecting means for detecting the temperature of the structure of the substrate processing apparatus. The apparatus state prediction apparatus according to any one of claims 1 to 3, wherein the information detected by (2) is collected as the environmental information.   The apparatus state prediction apparatus according to claim 1, wherein the substrate processing apparatus is an exposure apparatus that exposes and transfers a mask pattern onto a substrate.   The apparatus state prediction apparatus according to claim 1, wherein the environment information collection unit collects the environment information via a network. An apparatus state prediction method for predicting an apparatus state of a substrate processing apparatus for processing a substrate,
An environmental information collecting step for collecting environmental information on the environment of the substrate processing apparatus;
Prediction for predicting the apparatus state of the substrate processing apparatus based on a relational expression indicating a correlation between the environment change and the apparatus state change of the substrate processing apparatus and the environment information collected in the environment information collecting step Steps,
A comparison step of comparing the prediction result predicted in the prediction step with a predetermined threshold;
And an execution step of executing a predetermined process based on the comparison result in the comparison step.   The apparatus state prediction method according to claim 10, wherein the relational expression is a regression equation in which the environment is an explanatory variable and the apparatus state is an objective variable. An apparatus information collecting step for collecting apparatus information relating to an apparatus state of the substrate processing apparatus;
The apparatus state prediction method according to claim 10, further comprising an update step of updating the relational expression based on the environment information and the apparatus information.   The said execution step includes the transmission step which transmits the maintenance data containing the said prediction result with respect to the management apparatus which manages the said substrate processing apparatus, It is any one of Claims 10-12 characterized by the above-mentioned. Device state prediction method.   The apparatus state prediction method according to claim 10, wherein the execution step includes a warning step of executing a warning process when the prediction result exceeds the threshold value.   The said execution step includes the adjustment step which performs the adjustment process of the apparatus state of the said substrate processing apparatus when the said prediction result exceeds the said threshold value, The any one of Claims 10-14 characterized by the above-mentioned. The apparatus state prediction method as described.   The environmental information collected in the environmental information collecting step includes the temperature, humidity and pressure inside the substrate processing apparatus, or the temperature, pressure, specific resistance of the liquid used in the substrate processing apparatus, and the outside of the substrate processing apparatus. 16. The apparatus state prediction method according to claim 10, wherein the apparatus state prediction method is at least one of a temperature, a humidity and an atmospheric pressure, and a temperature of a structure portion of the substrate processing apparatus. In an exposure apparatus management system for exposing and transferring a mask pattern onto a substrate,
Environmental measuring means for measuring environmental conditions inside and outside the exposure apparatus;
Storage means for storing a relational expression indicating a correlation between a change in the environmental state measured by the environmental measurement means and a change in the apparatus state of the exposure apparatus;
Prediction means for predicting the apparatus state of the exposure apparatus based on the relational expression and the measurement result of the environment measurement means;
Maintenance data including the prediction result, the measurement result, and the relational expression, transmitting means for transmitting through the network;
An exposure apparatus management system comprising: a management apparatus that receives the transmitted maintenance data and records and manages the apparatus state of the exposure apparatus.   The environment measuring means includes temperature, humidity and pressure inside the exposure apparatus, temperature, pressure, specific resistance of liquid used in the exposure apparatus, temperature, humidity and pressure outside the exposure apparatus, and the exposure. 18. The exposure apparatus management system according to claim 17, wherein at least one of the temperatures of the structure portion of the apparatus is measured.   19. The exposure apparatus management system according to claim 17, wherein the management apparatus determines a maintenance plan for the exposure apparatus based on the maintenance data.

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