Abstract:
A scanning exposure apparatus for exposing a substrate to a pattern of a reticle. The apparatus includes an exposure system which exposes the substrate to the pattern with respect to a unit region, to which the pattern is transferred, of the substrate, by relatively moving the reticle and the substrate, a control system which controls an operation of the exposure system, the control system determining whether a condition of an exposure performed by the exposure system is within a tolerance during the exposure, and causing the exposure system to continue exposing a remaining region in the unit region of the substrate to the pattern, even after the control system determines that the condition is out of the tolerance for the unit region, and a user interface system which indicates information for identifying the unit region, for which the control system determines that the condition is out of the tolerance, of the substrate.

Description:
This application is a divisional application of U.S. patent application Ser. No. 10/676,156, filed Oct. 2, 2003, now U.S. Pat. No. 6,940,584 which is a divisional application of U.S. patent application Ser. No. 09/858,964, filed May 17, 2001, which issued as U.S. Pat. No. 6,657,703 on Dec. 2, 2003. 

   FIELD OF THE INVENTION 
   The present invention relates to an exposure apparatus used for photolithography in the manufacturing process of a semiconductor integrated circuit, liquid crystal display element, or the like, a maintenance method therefor, a semiconductor device manufacturing method, and a semiconductor manufacturing factory. 
   BACKGROUND OF THE INVENTION 
     FIG. 13  is a flow chart showing the focus algorithm of a stationary exposure apparatus (stepper). A focus on a wafer as a substrate loaded onto a wafer stage is measured at a focus measurement shot out of several representative shots on the wafer (step  1301 ). A global approximate plane as a linear plane which represents the wafer surface is calculated by, e.g., least-square approximation from the obtained focus measurement data (step  1302 ). The target value of the wafer stage in the Z direction when the wafer stage is driven to locate the wafer surface on the global approximate plane is called a global focus target value, and its target values in the ωx and ωy directions at this time are called global tilt target values. 
   Shots subjected to global focus/tilt measurement simultaneously undergo alignment measurement at, e.g., alignment mark positions ( 1401   x ,  1401   y ,  1402   x ,  1402   y ,  1403   x ,  1403   y ,  1404   x , and  1404   y ) of shots hatched on the wafer in  FIG. 14 .  FIG. 14  is a view showing a shot position on the wafer subjected to global focus measurement. To increase the precision of the measured global tilt amount and that of the rotation angle in the θ direction in global alignment, measurement spans in the X and Y directions are preferably widened, and the shots are desirably near the periphery of the wafer. 
   In  FIG. 13 , an X-Y stage moves stepwise to a target exposure shot position (step  1303 ). At the same time, a Z tilt wafer stage moves to a focus/tilt position in the exposure shot that is estimated from the global approximate plane (step  1304 ). Upon the completion of movement, a focus is measured again at the exposure position (step  1305 ). Focusing driving (step  1307 ) and focus measurement (step  1305 ) are repeated until the focus tolerance check passes (step  1306 ). In focus measurement (step  1305 ), a focus sensor measures focus measurement points in a plurality of exposure shots as shown in  FIG. 15 , and a linear approximate plane obtained from the measurement values is set as a wafer surface. Wafer stage target values for performing focusing so as to locate the wafer surface on an image plane are sequentially calculated.  FIG. 15  is a view showing the layout of focus measurement points within an exposure shot in the stationary exposure apparatus. 
   In  FIG. 15 , ch 1  to ch 5  are focus measurement points, one measurement point is formed from five marks ( 1501   a  to  1501   e ), and the average of the measurement values of the respective marks in the focus direction is used as focus measurement data for each point (ch 1  to ch 5 ). An exposure shot  1502  is measured at a plurality of focus measurement points (ch 1  to ch 5 ). For example, when the focus measurement value of ch 5  greatly deviates from those of ch 1  to ch 4 , the wafer surface is regarded to have a defect and is not exposed (case A). Alternatively, as for a greatly different measurement point, its measurement value is not used as focus measurement data, and an approximate plane is calculated from the remaining focus measurement points (case B). 
   If the focus tolerance passes, the flow waits for convergence of residual vibrations in the X and Y directions generated in the step of focus driving/Abbe correction driving (step  1307 ) in  FIG. 13  (step  1308 ), and exposure starts (step  1309 ). In step  1310 , whether all the shots have undergone the exposure sequence is checked. If N in step  1310 , the focus algorithm (steps  1303  to  1310 ) is repeated by using the first measured global approximate plane data (step  1302 ). 
   The surface of a process wafer may be corrugated by about 5 to 10 [μm] during the manufacturing process. When such a wafer is to be exposed, the exposure sequence is interrupted at the shot of a corrugated portion, and the shot does not allow exposure in a prior art like case A. In this case, in the prior art, the exposure sequence shifts to process the next shot without exposing the shot of a projecting portion. At the unexposed shot, the residual resist amount is larger than that at peripheral shots in the resist developing process, and may adversely affect a resist image at the peripheral shots. 
   If a focus error is generated by a wafer, the job aborts in the prior art, and the exposure sequence enters a manual operation mode where the operator determines processing of the defective shot. 
   If a focusing error is generated under the influence of dust or the like attached to a wafer chuck, the chuck must be cleaned to remove its contamination. In a prior art like case B, however, no focusing error is detected, and the contamination of the wafer chuck must be estimated from the wafer developing result. 
   SUMMARY OF THE INVENTION 
   The present invention has been made to overcome the conventional drawbacks, and has as its object to provide an exposure apparatus which minimizes the influence of a defective shot on peripheral shots, reduces defective shots, reduces misoperations caused by the operator, and detects contamination of a wafer chuck within the exposure process. The present invention also provides a maintenance method therefor, a semiconductor device manufacturing method, and a semiconductor manufacturing factory. 
   To overcome the above drawbacks, according to the first aspect of the present invention, there is provided an exposure apparatus which has a stage for aligning a substrate surface to an imaging plane on the basis of a detection signal from a focus sensor, moves the substrate by the stage, transfers a projection pattern, and exposes the substrate, comprising a controller for, when an exposure shot region on the substrate cannot converge to a predetermined precision, determining the exposure shot as an error, and controlling the stage so as to move the substrate to a predetermined position upon determination of the error, and an exposure unit for forcibly transferring the projection pattern onto the substrate at the predetermined position in the exposure shot and exposing the substrate. 
   According to the second aspect of the present invention, there is provided an exposure apparatus for transferring a projection pattern onto a substrate and exposing the substrate while scanning the substrate by a stage, comprising a controller for, when an exposure shot region on the substrate cannot converge during scan to a predetermined focus precision or leveling precision, a predetermined two-dimensional sync control precision, or a predetermined exposure amount control precision, determining the exposure shot as an error, and controlling the stage so as to move the substrate to a predetermined position upon determination of the error, and an exposure unit for forcibly transferring the projection pattern onto the substrate at the predetermined position in the exposure shot and exposing the substrate. 
   According to the third aspect of the present invention, there is provided an exposure apparatus for transferring a projection pattern onto a substrate and exposing the substrate while scanning the substrate, comprising a controller for, when an exposure shot region cannot converge to a predetermined focus precision during scan, determining the exposure shot as an error, and controlling a shot beam from an exposure light source upon determination of the error. 
   According to the present invention, there is provided a semiconductor device manufacturing method comprising the steps of installing manufacturing apparatuses, for performing various processes, including any one of the above-described exposure apparatuses, in a semiconductor manufacturing factory, and manufacturing a semiconductor device by using the manufacturing apparatuses in a plurality of processes. 
   According to the present invention, there is provided a semiconductor manufacturing factory comprising manufacturing apparatuses, for performing various processes, including any one of the above-described exposure apparatuses, a local area network for connecting the manufacturing apparatuses, and a gateway which allows the local area network to access an external network outside the factory, wherein information about at least one of the manufacturing apparatuses can be communicated. 
   According to the present invention, there is provided a maintenance method for any one of the above-described exposure apparatuses that is installed in a semiconductor manufacturing factory, comprising the steps of causing a vendor or user of the exposure apparatus to provide a maintenance database connected to an external network of the semiconductor manufacturing factory, authorizing access from the semiconductor manufacturing factory to the maintenance database via the external network, and transmitting maintenance information accumulated in the maintenance database to the semiconductor manufacturing factory via the external network. 
   According to the fourth aspect of the present invention, any one of the above-described exposure apparatuses further comprises a display, a network interface, and a computer for executing network software, and maintenance information of the exposure apparatus can be communicated via the computer network. 
   Other objects and advantages besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part thereof, and which illustrate an example of the invention. Such an example, however, is not exhaustive of the various embodiments of the invention, and, therefore, reference is made to the claims which follow the description for determining the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing the hardware arrangement of an exposure apparatus according to an embodiment of the present invention; 
       FIG. 2  is a view showing a state when a wafer surface is driven to a global tilt plane; 
       FIG. 3  is a view showing the positional relationship between an exposure slit and focus measurement points on the imaging plane in the exposure apparatus according to the embodiment of the present invention; 
       FIG. 4  is a flow chart showing an example of an exposure sequence in the exposure apparatus according to the embodiment of the present invention; 
       FIG. 5  is a view showing the layout of focus measurement positions and an exposure slit within an exposure shot; 
       FIG. 6  is a view showing an example of operation buttons displayed upon generation of a focus control error in the exposure apparatus according to the embodiment of the present invention; 
       FIG. 7  is a view showing an example of the user interface window of the exposure apparatus according to the embodiment of the present invention; 
       FIG. 8  is a view showing the concept of a semiconductor device production system including the exposure apparatus according to the embodiment of the present invention when viewed from a given angle; 
       FIG. 9  is a view showing the concept of the semiconductor device production system including the exposure apparatus according to the embodiment of the present invention when viewed from another given angle; 
       FIG. 10  is a view showing an example of a user interface in the semiconductor device production system including the exposure apparatus according to the embodiment of the present invention; 
       FIG. 11  is a flow chart for explaining the flow of a device manufacturing process by the exposure apparatus according to the embodiment of the present invention; 
       FIG. 12  is a flow chart for explaining a wafer process by the exposure apparatus according to the embodiment of the present invention; 
       FIG. 13  is a flow chart showing the focus (exposure) algorithm of a conventional stationary exposure apparatus; 
       FIG. 14  is a view showing a shot position on a wafer subjected to global focus measurement in the conventional stationary exposure apparatus; and 
       FIG. 15  is a view showing the layout of focus measurement points within an exposure shot in the conventional stationary exposure apparatus. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 
   [Exposure Apparatus] 
     FIG. 1  shows the hardware arrangement of an exposure apparatus according to an embodiment of the present invention. A reticle  109  set on a reticle stage  108  is scanned at a constant speed in the direction indicated by an arrow in  FIG. 1  under the control of a reticle stage controller  103 . Part of a pattern image on the reticle  109  serving as a master is horizontally reversed by a projection optical system  110  and projected onto an imaging plane on a focus stage  112 . The focus stage  112  is mounted on an alignment stage  113  and performs alignment in the Z direction and tilt directions (ωx and ωy). The alignment stage  113  is drivable in the X, Y, and θ directions and is scanned at a constant speed by a wafer stage controller  101  in the direction indicated by an arrow in  FIG. 1 , i e., a direction opposite to the driving direction of the reticle stage  108  during scan exposure. The ratio of the scan speeds of the alignment stage  113  and reticle stage  108  is determined from the projection magnification of the projection optical system  110  and the scaling ratio of a transferred image. 
   A focus measurement sensor  111  as a focus detection mechanism is fixed to an apparatus housing which contains the projection optical system  110 , and measures the focus direction of a wafer  120  serving as a substrate set on the focus stage  112 . A signal obtained by the focus measurement sensor  111  is converted into a focus measurement value  105  of an expression corresponding to the coordinate system of the wafer stage by a focus signal processing unit  102 , and the focus measurement value  105  is transferred to the wafer stage controller  101 . In shot exposure, the wafer stage controller  101  controls the manipulation quantity of the focus stage  112  so as to allow the surface of the wafer  120  to reach a focus target value corresponding to an imaging plane included in the argument of an exposure command  107  transferred from a main sequence controller  104  in advance. 
   Reference numeral  115  denotes an illumination optical system which disperses the coherence of an exposure laser beam from a pulse laser source  116  and shapes the light quantity distribution of a slit shape. The wafer stage controller  101  controls in real time the emission start and stop timings of a pulse laser by using an emission enable signal  117  in accordance with the stage position during scan. 
   The main sequence controller  104  designates to the alignment stage  113  by using the exposure command  107  a scan driving target value included in a command issued for each shot, and designates to the focus stage  112  a focus target value to an imaging plane and an initial focus target value (to be referred to as a neighboring focus target value hereinafter) for performing preset before scan exposure. The main sequence controller  104  sends a pulse energy/wavelength command signal  118  to the pulse laser source  116  for each shot or every predetermined timing. After one shot is exposed, a focus control target value  106  of the focus stage  112  calculated by the wafer stage controller  101  is sent back to the main sequence controller  104  in order to achieve alignment in the focus direction of the shot. This data is used as the neighboring focus target value of a subsequent shot. The neighboring focus target value is used as the target value of the focus/tilt axis of the wafer stage in executing forced exposure (to be described with reference to a flow chart) when the wafer  120  is so corrugated as to generate a focusing error at the next exposure shot. When the focusing error shot is the first exposure shot on the wafer  120 , a global tilt target value (to be described later) is used as the target value of the focus/tilt axis of the wafer stage in executing forced exposure. 
     FIG. 2  is a view showing a state after the wafer stage is driven to a position where the global approximate plane is measured as (Z,ωx, ωy)=(0,0,0) when the next global focus/tilt measurement is similarly done by using a value obtained by global focus/tilt measurement. In  FIG. 2 , the same reference numerals as in  FIG. 1  denote the same parts. 
   The surface of the wafer  120  is parallel to a driving locus (wafer stage traveling surface  201 ) with a constant target value in the Z direction of the wafer stage. As far as the surface of the wafer  120  is ideally parallel, no defocus occurs below an exposure slit in scan exposure in this stage. In practice, however, local corrugations exist on the surface of the wafer  120  to a considerable amount with respect to the depth of focus. Thus, focus is measured during exposure, and a laser must be focused not to defocus the surface of the wafer  120  immediately below the slit. This amount is 3 to 4 at a maximum with respect to the global tilt plane on a general single-side-polished wafer  120 , though the amount changes depending on the surface polishing step or process of the wafer  120 . To the contrary, the focus control precision assigned to focus control in exposure is about 0.1 according to the 0.15 μm L/S rule. 
     FIG. 3  shows the positional relationship between an exposure slit and focus measurement points on the imaging plane in the exposure apparatus according to the embodiment of the present invention. When the alignment stage  113  ( FIG. 2 ) scans the wafer in the direction indicated by arrow  1 , focus measurement points a, b, and c are used, and when the alignment stage  113  scans the wafer in the direction indicated by arrow  2 , focus measurement points A, B, and C are used. A focus measurement point S is also set at the center of the shot. Focus is measured at combined points (a, b, c, S) and (A, B, C, S) during one cycle of a plurality of focus measurements even during a scan in order to confirm a convergence result in the focus direction during exposure. In the focus measurement cycle, an obtained focus measurement value is determined as a focus convergence error under the following conditions (when convergence within a given focus alignment precision fails). 
   (i) Variations in measurement values from the average of measurement values at a, b, and c exceed a prescribed allowable amount. 
   (ii) An absolute tilt amount calculated from ωy=(a−c)/L exceeds a prescribed allowable amount. 
   (iii) An absolute focus amount calculated from Z=(a+b+c)/3 exceeds a prescribed allowable amount. 
   (iv) The differences between Z and ωy obtained by previous focus measurement, and Z and ωy obtained by current focus measurement exceed prescribed allowable amounts, respectively. 
   The focus convergence error occurs in the following two cases (A) and (B). 
   (A) A convergence error (non-exposure focus error) before exposure starts because an exposure shot is measured for a focus measurement point but the exposure slit does not enter the exposure area. 
   (B) A convergence error (exposure abort focus error) when the exposure slit enters the exposure area and exposure already starts. 
   In case (A), the emission enable signal  117  in  FIG. 1  is immediately disabled to stop emission of the pulse laser source  116  (shield an exposure beam). In a slow light source system such as a mercury lamp light source, a high-speed shutter may be arranged in the illumination optical system  115  to shield an exposure beam. 
   In case (B), exposure can be immediately stopped, like case (A), which produces an exposed portion and an unexposed portion within a shot. When exposure intermittently aborts within a shot, a portion where exposure has aborted is stored in the wafer stage controller  101  in  FIG. 1 , and emission of the illumination optical system  115  starts in a retry mode at the portion where exposure was aborted. In this embodiment, exposure does not abort in such a case for the sake of descriptive simplicity, and exposure continues to the final portion left in the shot region by forcibly exposing the shot. At this time, exposure must continue without any focus measurement value. The values Z and ωy (focus and tilt position) at the final focus measurement position measured normally are most desirably used. A global focus measurement value or the neighboring focus value of a previous shot may be used. 
   Also, in a stationary exposure apparatus, a focus control error occurs when, for example, the focus tolerance check does not pass (step  1306 ) even if the convergence loop for performing focus measurement (step  1305 ), focus tolerance check (step  1306 ), and focus driving/Abbe correction driving (step  1307 ) is repeated a predetermined number of times in the flow chart of the prior art in  FIG. 13 , or when the variance of measurement values at respective measurement points from a linear approximation plane calculated between focus measurement points in a shot shown in  FIG. 15  exceeds a prescribed amount. 
     FIG. 4  shows an example of an exposure sequence in the exposure apparatus according to the embodiment of the present invention. A command to a light source upon generation of a focus control (convergence) error is determined, and emission of the exposure light source is controlled in real time by the wafer stage controller  101  ( FIG. 1 ). The wafer stage controller  101  transmits for each shot to the main sequence controller  104  ( FIG. 1 ) a focus control error status and information representing whether a shot has been exposed. 
   The flow chart in  FIG. 4  shows the sequence of the main sequence controller  104  performed based on information from the wafer stage controller  101  that is obtained for each exposure shot. Alignment of the wafer  120  on the wafer stage is measured by an alignment scope  114  before the exposure sequence. After a driving target value for each exposure shot is determined, the main sequence controller  104  enters this sequence. 
   In  FIG. 4 , if an exposure command  401  for each shot is received, the wafer stage and reticle stage temporarily skip to a pre-scan start point, and scan starts. During scan, a focus measurement unit sequentially measures a focus from  507  to  501  in  FIG. 5 , and calculates the target value of the wafer stage from the measurement results.  FIG. 5  is a view showing the layout of focus measurement positions and an exposure slit  301  ( FIG. 3 ) within an exposure shot  508 . 
   Processing when a focus control error occurs will be explained with reference to  FIG. 4 . 
   In  FIG. 4 , the focus measurement points a, b, and c ( FIG. 5 ) are set before the exposure slit  301  ( FIG. 5 ) in the scan direction, so that a focus control error (focus convergence error)  402  may occur before or during exposure. At this time, the exposure apparatus immediately displays, e.g., a message window on a user interface to display an error message ( 403 ). 
   For a focus convergence error, whether the target shot has already been exposed is determined ( 404 ), and if the target shot has already been exposed, the flow shifts to a sequence  405  of determining whether the current mode is an automatic continuation mode. If the focus control error  402  occurs, whether the exposure slit  301  ( FIG. 5 ) enters the exposure area and exposure starts is checked. If exposure does not start, processing of inhibiting emission of the pulse light source is immediately executed; if exposure starts, the target shot is completely exposed without stopping emission of the light source. If the target shot is not exposed or a focus control error is generated by a factor such as a disturbance from a floor, retry of the same exposure may succeed. 
   In a sequence  406 , whether an automatic operation mode is set is determined. If Yes in sequence  406 , the shot (focus convergence error shot) is exposed under the same conditions. In step  407 , whether a focus control error occurs even upon retry in the same shot is checked. If retry fails once, a forced exposure sequence  417  is executed. In forced exposure  417 , not a value obtained by measuring the wafer surface, but a global focus/tilt target value which is a target value independent of a focus measurement sensor value, or the focus/tilt target value of the wafer stage obtained during the exposure time of the final portion of the previously exposed shot is adopted as a fixed target value during scan. In automatic forced exposure  417 , even if the reliability of the focus measurement value degrades owing to, e.g., a fault of the focus measurement system, the exposure sequence continues with an improper focus/tilt target value. Forced exposure  417  should, therefore, be limited within a finite number of successive shots. In a sequence  413 , if the result of counting the number of successive operations of forced exposure  417  exceeds five shots, the job stops even in the automatic continuation mode (sequence stop  414 ). 
   If the job stops, buttons as shown in  FIG. 6  are displayed on the user interface in order to cause the operator to select (determine) subsequence processing, and the flow waits for operator designation (sequence  415 ).  FIG. 6  is a view showing an example of operation buttons displayed upon generation of a focus control error in the embodiment of the present invention. In  FIGS. 4 and 6 , a CONT (Continue) button is for designating continuation of processing. If the operator clicks the CONT button, exposure of a shot suffering a focus convergence error is skipped, and the flow advances to the exposure sequence of the next shot (shot B scan exposure command  416 ). An ABORT (Abort) button means the end of the exposure job ( 411 ), and is for aborting the job in progress and recovering all wafers in process. An RW (Reject Wafer) button is for aborting the exposure sequence of only the current exposure target wafer and recovering the wafer ( 412 ). If No in sequence  406 , the job immediately aborts (sequence stop  408 ), and the flow waits for a user button input shown in  FIG. 6  ( 409 ). Choices in this case are a sequence  415 , a RETRY (Retry) button for performing retry processing for a shot suffering a focus control error, and a FORCE (Force) button for performing forced exposure processing  410  when focusing fails. 
   When a focus control error is generated by the wafer stage controller  101  ( FIG. 1 ) and part of the target shot has already been exposed, the shot has already been exposed in a defocused state. If Y in the sequence  405  (automatic continuation mode), a check in the sequence  413  is performed, and the flow shifts to processing  416  of the next shot; if N, the exposure sequence aborts (sequence stop  414 ), and the flow waits for a user button input ( 415 ). 
   The position of the shot suffering the focus control error is stored in the main sequence controller  104  ( FIG. 1 ). The generation factors of focus control errors are classified into (A) defects of the wafer surface state, (B) contamination of the wafer chuck surface by a resist peeled from a wafer, (C) vibrations by a disturbance from a floor, and (D) apparatus faults. Among them all, factor (B) can be separated from the cause because focus control errors occur at the same shot position commonly to respective wafers. This embodiment has a function of storing a shot position where focus control errors occur on respective wafers, regarding the focus control errors generated at the same shot position as errors generated by contamination of the wafer chuck, and aborting the job. When contamination of the wafer chuck is detected by this function, the wafer chuck can be exchanged or cleaned to rapidly determine the factor of a focus control error and increase the shot yield. 
   As for a function of comparing the number of forcedly exposed shots in the automatic continuation modes  405 ,  406 , and  413  with a predetermined number of shots (five shots), selection of execution/non-execution of the automatic continuation mode and designation of a predetermined number of shots can be achieved via a man-machine interface connected to the main sequence controller  104  ( FIG. 1 ). By applying the present invention, it can also be easily realized to record the total number of shots subjected to forced exposure processing for each wafer or lot and transmit the total number to an on-line host machine. When, for example, contamination of the wafer chuck is identified, the operator can be warned of this via the man-machine interface. 
   Further, the present invention can be applied as error processing when the sync control precision in the alignment direction or the total exposure amount in the exposure slit that is calculated from a monitored illuminance exceeds a preset allowable amount. Whether sync control or exposure amount control achieves a desired precision can be determined only after scan exposure starts. If emission of the exposure light source stops because the desired precision cannot be achieved, a partially unexposed portion is formed and adversely affects peripheral shots which have normally been exposed in developing the resist. Hence, the target shot is preferably completely exposed by forced exposure without stopping exposure when the sync control precision or exposure amount control precision deviates from a standard precision during exposure (to be referred to as a standard precision short error hereinafter). The next shot is normally processed with a high possibility for a standard precision short error generated by floor vibrations, a local factor of the wafer  120  ( FIG. 1 ), or misfire of the pulse laser source  116  (FIG.  1 ) (omission of emission pulses). In many cases, a standard precision short error generated by the service life of the pulse laser source  116  or a fault of the exposure apparatus occurs at successive shots. Thus, the algorithm of the automatic continuation mode can be similarly applied to monitoring of the exposure amount control precision and sync control precision. The job can continue without stopping the apparatus for an inevitable standard precision short error caused by a local factor, resulting in high apparatus availability. A standard precision short error generated by an apparatus fault or the like can be determined to stop the sequence with a minimum damage by monitoring whether the error is generated at successive shots. As another method of stopping the sequence owing to repeated standard precision short errors, the errors are identified based on the total number of generated errors or the number of generated errors (generation rate) within a predetermined number of exposure shots, other than monitoring of errors at successive shots. 
   As for the sync precision specification, exposure precision specification, and focus/leveling precision specification of the apparatus, the guaranteed performance is generally defined by sigma. The present invention is effective as a means for determining whether the standard performance of the apparatus is actually achieved and monitoring the standard performance during the operation of the apparatus. This is because an exposure shot which does not probabilistically meet the standard precision necessarily exists, and if an error is determined by giving attention to the exposure result of a single shot, the sequence may stop even during normal operation in terms of the standard definition (sigma). 
   A stationary exposure apparatus adopts a sequence in which exposure starts after the focus convergence is achieved in advance. When a focus convergence error occurs in the focus convergence process, exposure can be stopped before it starts by canceling emission of a light source or keeping the shutter closed. The stationary exposure apparatus does not require processing  404  of determining whether part of a shot has been exposed upon generation of a focus convergence error in  FIG. 4 , and processing  405  of determining whether the exposure apparatus operates in the automatic continuation mode. The remaining processes can be similarly applied as the focus control error processing step in the stationary exposure apparatus. 
     FIG. 7  is a view showing an example of the user interface window of the exposure apparatus according to the embodiment of the present invention. Reference numeral  740  denotes a window for displaying a sequence in progress;  741 , a window for displaying an error and warning generated during execution of a job; and  742 , a wafer shape to be exposed, on which exposure shots  701  to  730  are hatched upon the completion of exposure. Of the exposure shots  701  to  730 , the exposure shots  705  and  706  represent shots suffering focus control errors and are hatched in a different color to allow the operator to discriminate them from normally exposed shots. Reference numeral  743  denotes an operation button. A permitted operation changes depending on a sequence which executes a job, and a menu displayed on the button  743  changes depending on the operation. If a re-exposure enable focus convergence error occurs in a mode other than the automatic continuation mode, operation buttons as shown in  FIG. 6  are displayed to wait for operator designation. 
   [Embodiment of Semiconductor Production System] 
   A production system for a semiconductor device (e.g., semiconductor chip such as an IC or LSI, liquid crystal panel, CCD, thin-film magnetic head, micromachine, or the like) using the exposure apparatus will be exemplified. A trouble remedy or periodic maintenance of a manufacturing apparatus installed in a semiconductor manufacturing factory, or maintenance service such as software distribution is performed by using, e.g., a computer network outside the manufacturing factory. 
     FIG. 8  shows the overall system cut out at a given angle. In  FIG. 8 , reference numeral  801  denotes a business office of a vendor (apparatus supply manufacturer) which provides a semiconductor device manufacturing apparatus. Assumed examples of the manufacturing apparatus are semiconductor manufacturing apparatuses for performing various processes used in a semiconductor manufacturing factory, such as pre-process apparatuses (e.g., a lithography apparatus including an exposure apparatus, a resist processing apparatus, and an etching apparatus, an annealing apparatus, a film formation apparatus, a planarization apparatus, and the like) and post-process apparatuses (e.g., an assembly apparatus, an inspection apparatus, and the like). The business office  801  comprises a host management system  808  for providing a maintenance database for the manufacturing apparatus, a plurality of operation terminal computers  810 , and a LAN (Local Area Network)  809  which connects the host management system  808  and computers  810  to build an intranet. The host management system  808  has a gateway for connecting the LAN  809  to Internet  805  as an external network of the business office, and a security function for limiting external accesses. 
   Reference numerals  802  to  804  denote manufacturing factories of the semiconductor manufacturer as users of manufacturing apparatuses. The manufacturing factories  802  to  804  may belong to different manufacturers or the same manufacturer (pre-process factory, post-process factory, and the like). Each of the factories  802  to  804  is equipped with a plurality of manufacturing apparatuses  806 , a LAN (Local Area Network)  811  which connects these apparatuses  806  to construct an intranet, and a host management  807  serving as a monitoring apparatus for monitoring the operation status of each manufacturing apparatus  806 . The host management system  807  in each of the factories  802  to  804  has a gateway for connecting the LAN  811  in the factory to the Internet  805  as an external network of the factory. Each factory can access the host management system  808  of the vendor  801  from the LAN  811  via the Internet  805 . The security function of the host management system  808  authorizes access of only a limited user. More specifically, the factory notifies the vendor via the Internet  805  of status information (e.g., the symptom of a manufacturing apparatus in trouble) representing the operation status of each manufacturing apparatus  806 , and receives response information (e.g., information designating a remedy against the trouble, or remedy software or data) corresponding to the notification, or maintenance information such as the latest software or help information. Data communication between the factories  802  to  804  and the vendor  801  and data communication via the LAN  811  in each factory adopt a communication protocol (TCP/IP) generally used in the Internet. Instead of using the Internet as an external network of the factory, a dedicated network (e.g., an ISDN) having high security which inhibits access of a third party can be adopted. Also, the user may construct a database in addition to the one provided by the vendor and set the database on an external network, and the host management system may authorize access to the database from a plurality of user factories. 
     FIG. 9  is a view showing the concept of the overall system of this embodiment that is cut out at a different angle from  FIG. 8 . In the above example, a plurality of user factories having manufacturing apparatus and the management system of the manufacturing apparatus vendor are connected via an external network, and production management of each factor or information of at least one manufacturing apparatus is communicated via the external network. In the example of  FIG. 9 , a factory having manufacturing apparatuses of a plurality of vendors and the management systems of the vendors for these manufacturing apparatuses are connected via the external network of the factory, and maintenance information of each manufacturing apparatus is communicated. In  FIG. 9 , reference numeral  901  denotes a manufacturing factory of a manufacturing apparatus user (e.g., a semiconductor device manufacturer) where manufacturing apparatuses for performing various processes, e.g., an exposure apparatus  902 , a resist processing apparatus  903 , and a film formation apparatus  904  are installed in the manufacturing line of the factory.  FIG. 9  shows only one manufacturing factory  901 , but a plurality of factories are networked in practice. The respective apparatuses in the factory are connected to a LAN  960  to build an intranet, and a host management system  905  manages the operation of the manufacturing line. The business offices of vendors (apparatus supply manufacturers) such as an exposure apparatus  910 , a resist processing apparatus manufacturer  902 , and a film formation apparatus manufacturer  930  comprise host management systems  911 ,  921 , and  931  for executing remote maintenance for the supplied apparatuses. Each host management system has a maintenance database and a gateway for an external network, as described above. The host management system  904  for managing the apparatuses in the manufacturing factory of the user, and the management systems  911 ,  921 , and  931  of the vendors for the respective apparatuses are connected via the Internet or dedicated network serving as an external network  900 . If a trouble occurs in any one of a series of manufacturing apparatuses along the manufacturing line in this system, the operation of the manufacturing line stops. This trouble can be quickly solved by remote maintenance from the vendor of the apparatus in trouble via the Internet  900 . This can minimize the stoppage of the manufacturing line. 
   Each manufacturing apparatus in the semiconductor manufacturing factory comprises a display, a network interface, and a computer for executing network access software and apparatus operating software which are stored in a storage device. The storage device is a built-in memory, hard disk, or network file server. The network access software includes a dedicated or general-purpose web browser, and provides a user interface having a window as shown in  FIG. 10  on the display. While referring to this window, the operator who manages manufacturing apparatuses in each factory inputs, in input items on the windows, pieces of information such as the type of manufacturing apparatus  1001 , serial number  1002 , subject of trouble  1003 , occurrence date  1004 , degree of urgency  1005 , symptom  1006 , remedy  1007 , and progress  1008 . The pieces of input information are transmitted to the maintenance database via the Internet, and appropriate maintenance information is sent back from the maintenance database and displayed on the display. The user interface provided by the web browser realizes hyperlink functions  1010 ,  1011 , and  1012 , as shown in  FIG. 10 . This allows the operator to access detailed information of each item, receive the latest-version software to be used for a manufacturing apparatus from a software library provided by a vendor, and receive an operation guide (help information) as a reference for the operator in the factory. Maintenance information provided by the maintenance database also includes information concerning the present invention described above. The software library also provides the latest software for implementing the present invention. 
   A semiconductor device manufacturing process using the above-described production system will be explained.  FIG. 11  shows the flow of the whole manufacturing process of the semiconductor device. In step  1  (circuit design), a semiconductor device circuit is designed. In step  2  (mask formation), a mask having the designed circuit pattern is formed. In step  3  (wafer manufacture), a wafer is manufactured by using a material such as silicon. In step  4  (wafer process) called a pre-process, an actual circuit is formed on the wafer by lithography using a prepared mask and the wafer. Step  5  (assembly) called post-process is the step of forming a semiconductor chip by using the wafer manufactured in step  4 , and includes an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step  6  (inspection), inspections such as the operation confirmation test and durability test of the semiconductor device manufactured in step  5  are conducted. After these steps, the semiconductor device is completed and shipped (step  7 ). For example, the pre-process and post-process are formed in separate dedicated factories, and maintenance is done for each of the factories by the above-described remote maintenance system. Information for production management and apparatus maintenance is communicated between the pre-process factory and the post-process factory via the Internet or a dedicated network. 
     FIG. 12  shows the detailed flow of the wafer process. In step  11  (oxidation), the wafer surface is oxidized. In step  12  (CVD), an insulating film is formed on the wafer surface. In step  13  (electrode formation), an electrode is formed on the wafer by vapor deposition. In step  14  (ion implantation), ions are implanted in the wafer. In step  15  (resist processing), a photosensitive agent is applied to the wafer. In step  16  (exposure), the above-mentioned exposure apparatus exposes the wafer to the circuit pattern of a mask In step  17  (developing), the exposed wafer is developed. In step  18  (etching), the resist is etched except for the developed resist image. In step  19  (resist removal), an unnecessary resist after etching is removed. These steps are repeated to form multiple circuit patterns on the wafer. A manufacturing apparatus used in each step undergoes maintenance by the remote maintenance system, which prevents a trouble in advance. Even if a trouble occurs, the manufacturing apparatus can be quickly recovered. The productivity of the semiconductor device can be increased in comparison with the prior art. 
   The above-described embodiment enables forced exposure when a wafer flatness defect is generated by the process. The influence on peripheral shots exposed normally in etching can be minimized to increase the wafer yield. 
   The above-described embodiment comprises a function of storing the generation position of a focus control error between the wafers when a wafer flatness defect is generated by the chuck. In addition to the above effects, contamination of the wafer chuck can quickly be found. 
   The above-described embodiment comprises a function of stopping exposure if scan exposure does not start and retrying exposure when a focus control error is generated under the influence of a disturbance from a floor. The ratio of erroneous exposure shots can be reduced to increase yield. 
   Moreover, the above-described embodiment comprises a function of automatically determining retry or forced exposure. The stop time of the apparatus due to a wait for an operator determination can be minimized to increase the apparatus availability. 
   The present invention is not limited to the above embodiments and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, to apprise the public of the scope of the present invention, the following claims are made.