JP2008198754A - Exposure system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convey a wafer automatically without manual help as much as possible in a case when a wafer is brought into a state where the same can not be retained on a wafer stage during conveyance by a wafer supporting unit and the subsequent conveyance can not be guaranteed. <P>SOLUTION: Measurement of existence of the wafer is effected through an absolute coordinate in the device utilizing the existing sensors 5, 6, 7 to determine the posture (amount, direction and inclination of deviation) of the wafer based on the information. The information is compared with a preset allowable amount to judge the possibility of the conveyance and when it is possible, the conveyance is carried out. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exposure apparatus that exposes a substrate such as a semiconductor wafer.

In recent years, the footprint of the apparatus has been expanded with the improvement of the performance of the semiconductor exposure apparatus. The reason for this is that the size of the unit itself has been increased for the purpose of improving the functions, and new units have been added for the purpose of adding functions.
However, in contrast to the above-mentioned benefits such as performance improvement, function improvement, and function addition, such an increase in size causes problems such as an increase in transport time due to a long transport distance and an increase in work time due to a decrease in equipment maintainability. Is causing. At this time, with respect to the former transport time, measures are taken by shortening the processing time. In addition, regarding the latter maintainability, the size itself is severely improved, and the work time is shortened by a modular structure of hardware, and the work is simplified by an automatic processing function without human intervention.

The present invention is also a technique related to the latter maintainability, and particularly aims at improving the workability by automating the apparatus.
An example of a function for the same purpose is to automatically open a maintenance door and place the chuck on a dedicated stage in order to replace the wafer suction support part (hereinafter referred to as a chuck) on the wafer stage. There is a function to replace the chuck (Patent Document 1). This is because with the increase in the size of the device described at the beginning, the exposure stage becomes difficult to access, that is, at a position close to the center away from the outer periphery of the device, which makes it difficult to work manually. To improve the situation. This not only reduces the work time, but also makes it possible to omit work with a high risk of interference in situations where various units are adjacent.
Japanese Patent Application Laid-Open No. 08-181057

The present invention relates to a technique for dealing with a case where an accident occurs in the transfer on a wafer stage. Specifically, when the wafer cannot be held by the wafer support unit during transfer (hereinafter referred to as wafer lost), and subsequent transfer cannot be guaranteed, the wafer transfer is determined. If possible, automatic transfer is performed. Technology to do.
The wafer lost as described above usually occurs at the timing when the wafer is transferred. This is because the wafer is always in the attracted state during the transfer, and it is rare that the transfer is stopped due to the deviation. On the other hand, there is a timing at which suction by vacuum is not performed during delivery, and there is a possibility that the posture may change slightly due to vibration or the like at that time.

Conventionally, in such a case, the control of the apparatus is stopped and the wafer is manually collected. This is because operating the device in a state where the wafer support is abnormal involves a risk of dropping the wafer, etc., and it is less risky to perform manual recovery while visually checking by a person. Because it was thought.
However, along with the increase in size of the device, opening the side panel of the device and acquiring the wafer inside the device is difficult in terms of distance, as well as sewing various unit gaps as described above, Accessing the wafer has a high risk of interference with other units.

On the other hand, depending on the position where the wafer exists and the suction state, there are not a few situations where the apparatus can be automatically transferred.
Therefore, the process of automatically unloading the wafer as much as possible or the process of correcting the position of the wafer is performed unless the wafer cannot be moved or there is a risk of interference with any hardware when the wafer is moved. It is desirable that
An object of the present invention is to provide an exposure apparatus that performs such desirable processing.

  In order to achieve the above object, an exposure apparatus according to the present invention includes a stage that holds and moves a substrate, a transfer unit that transfers the substrate between the stage and conveys the substrate, and a stage. An exposure apparatus that exposes the substrate by moving the stage based on the measured position, and measuring the position of the target region on the surface of the held substrate. Whether the suction state of the substrate is correct or not is determined, and when the suction state is abnormal, the amount of positional deviation of the substrate is measured using the measuring device, and the stage and the stage according to the measured positional deviation amount The substrate is transferred to and from the transport unit.

  According to the present invention, for example, it is possible to provide an exposure apparatus that performs a desirable process as described above.

  An exposure apparatus according to a preferred embodiment of the present invention includes a wafer stage that holds and moves a wafer (substrate), and a transfer unit that transfers the wafer to and transfers the wafer to and from the stage. Have. Furthermore, a measuring device for measuring the position of a target area on the surface of the wafer held on the stage is provided, and the stage is moved based on the measured position to expose the wafer. Then, it is determined whether the wafer is attracted by the stage, and when the attracted state is abnormal, the wafer misalignment amount is measured using the measuring instrument, and the measured misalignment amount is calculated. In response, the wafer is transferred between the stage and the transfer unit.

Here, as the measuring instrument, a focus sensor that measures the height of the target region (measurement shot) on the surface of the wafer, an alignment scope that measures the position of the alignment mark on the wafer (on the substrate), or the like is used. it can.
The amount of positional deviation of the wafer on the wafer stage is measured based on the determined presence / absence of the wafer surface at each of a plurality of predetermined locations on the wafer stage. To do. Alternatively, the position of at least three end portions of the wafer is detected using the measuring instrument, and the amount of displacement is measured based on the detected positions of the at least three end portions. These misregistration amounts may be misregistration amounts on a predetermined coordinate plane or wafer tilt amounts.

The exposure apparatus according to the present embodiment determines whether or not the positional deviation amount is within a predetermined allowable range, and when it is determined that the positional deviation amount is within the allowable range, the stage and the stage Wafers are transferred to and from the transfer unit. On the other hand, when it is determined that the positional deviation amount is not within the allowable range, information related to the determination result is notified.
The stage includes a chuck for adsorbing a wafer and delivery pins that can penetrate the chuck and adsorb the wafer. When at least one of the chuck and the delivery pin cannot normally suck the wafer, it is determined that the suction state is abnormal. The stage sucks the wafer by vacuum, and whether the suction state is correct or not can be determined based on the pressure of the vacuum.

In the exposure apparatus according to the present embodiment, the wafer cannot be held by the wafer support part during transfer on the wafer stage, and when subsequent transfer cannot be guaranteed, the existing sensor (measuring instrument) is used to change the posture of the substrate. measure. Then, if there is no risk of interference as compared with a preset allowable value, it is carried out of the apparatus. In addition, when the wafer is delivered, the wafer position is shifted to correct the position of the wafer and perform reprocessing.
Accordingly, it is possible to cope with a low risk of secondary disaster as compared with the conventional manual work. In addition, when reprocessing is possible due to the correction of the posture, it is possible to process a wafer that has been subjected to rework or the like in the past, so that an improvement in productivity can be expected. Furthermore, since an existing sensor is used without adding a new sensor, the system can be automated without increasing the cost of the apparatus.

There is no problem if the measurement means including the sensor moves and can measure any position of the wafer, but in general, the position of the sensor is fixed, and the wafer may be required for measurement. In many cases, in this case, there is a problem whether it can be transported in the first place.
In this case, whether the transfer is possible or not is determined based on the state of wafer adsorption.

  For example, in a chuck that supports the outer periphery of the wafer as shown in FIG. In other words, if the wafer cannot be vacuum adsorbed (hereinafter referred to as “adsorption”) and the wafer can be adsorbed by an exchange support portion (hereinafter referred to as “delivery pin”) that supports a location near the center of the wafer used when delivering the wafer, It is assumed that the deviation is small. At this time, it is possible to measure with a sensor while driving in a state where the wafer is sucked by the delivery pin.

  As a premise described above, a case where an abnormality occurs in the wafer support is considered that the chuck cannot be sucked due to deformation of the wafer. At this time, it is known that the deformation of the wafer is mainly caused by the heat treatment process, and the shape of the wafer is often a bowl shape having a larger curvature at the outer periphery of the wafer. Therefore, it is considered that there is a high possibility that suction can be performed at the replacement support portion even when the chuck cannot perform suction.

  In such a situation, although there is a possibility that the wafer is misaligned, it is presumed that the misalignment of the wafer is small only by complete adsorption. Therefore, it is possible to perform safer processing by automatically carrying the wafer if possible by examining the state of the wafer, rather than taking the above-described risk. Moreover, even if automatic conveyance is not possible, it is useful information for manual collection.

  If the chuck or the replacement support unit does not confirm the suction, it is possible that the wafer is not on the support unit or that the suction is abnormal due to contamination such as contamination. Further, even when the replacement support portion does not have a suction mechanism, the guarantee of wafer driving cannot be determined. In this case, the present invention can be applied by assuring the driving of the wafer by another means such as confirming the posture by imaging with a camera.

  When it is determined that measurement is possible based on the above assumption, the wafer surface is measured using a sensor provided in the apparatus. At this time, the sensor to be used is originally used for focus measurement and alignment measurement, but in this embodiment, it is simply used to confirm whether or not the wafer surface can be measured, that is, whether or not a wafer is present.

  Briefly describing the means for calculating the attitude, a sensor is used to measure the presence / absence of a wafer using absolute coordinates on the apparatus stage, and the amount of wafer position deviation is calculated based on that information. For example, when several points on the wafer periphery are measured and a specific number of consecutive points cannot be measured, it is considered that a deviation has occurred in the direction of the vector connected from that portion to the wafer center. Furthermore, if the sensor used is a focus sensor, the tilt of the wafer surface can be calculated simultaneously.

According to the present embodiment, the posture of the wafer is measured using the above-described means, and compared with a preset allowable value, it can be carried out of the apparatus if there is no risk of interference. . In addition, when the wafer is delivered, it is possible to re-process the wafer by correcting the position of the wafer by shifting the wafer.
Accordingly, it is possible to cope with a low risk of secondary disaster as compared with the conventional manual work. Further, when reprocessing is possible by correcting the posture, it is possible to process a wafer that has been subjected to rework or the like in the past, so that improvement in productivity can be expected. Furthermore, since an existing sensor is used without adding a new sensor, the system can be automated without increasing the cost of the apparatus.

Embodiments of the present invention will be described below with reference to the drawings.
[Example 1]
FIG. 1 shows an example of a semiconductor exposure apparatus to which the present invention is applied. The name and role of each unit will be described. Reference numeral 1 denotes a reticle. Reference numeral 2 denotes a reticle stage for scanning the reticle 1. The reticle stage 2 moves on the reticle stage guide 3. Reference numeral 4 denotes a projection system (projection optical system). Reference numeral 5 denotes an alignment scope for pattern position measurement. Reference numerals 6 and 7 denote a focus detection system (light projecting unit) and a focus detection system (light receiving unit) of a focus measurement system for measuring the position of the upper surface of the wafer.

  Reference numeral 8 denotes a wafer, and the chuck 9 holds the wafer 8. The fine movement stage 10 can finely drive the chuck in each direction of X, Y, Z, θ (rotation in a direction parallel to the XY plane) and tilt (tilt with respect to the XY plane). The coarse movement stage 11 can drive the fine movement stage 10 in the XY directions. The coarse movement stage 11 drives on the wafer stage surface plate 12.

  In the exposure process, the position of the pattern on the wafer 8 is measured by the alignment scope 5 arranged adjacent to the projection system 4 via a distance called a baseline length, and then the wafer 8 is projected by the coarse movement stage 11 on the projection system 4. To feed under. Then, the reticle 1 and the wafer 8 are scanned relative to the projection system 4 at a magnification ratio of the projection system 4 so that the pattern on the reticle 1 is transferred to a predetermined position. The pattern on 1 is transferred to a predetermined position on the wafer 8. During the transfer, the position of the upper surface of the wafer is sequentially measured by the focus measurement system, and exposure is performed while the wafer 8 is moved by the fine movement stage 10 so that the position of the upper surface of the wafer coincides with the image plane position of the projection system 4. It is operating.

  FIG. 2 shows an example of a transport system in the apparatus of FIG. The name and role of each unit will be described. The inline unit 24 is a station used for delivering a wafer to the coater developer. As another form, a plurality of wafers may be placed in an open cassette and set in the open cassette elevator 20 and delivered to the apparatus. A wafer carry-in hand (hereinafter referred to as SCH) 25 conveys a wafer in an open cassette placed in the inline unit 24 or the open cassette elevator 20 to a pre-alignment unit (hereinafter referred to as PA) 26 at the time of carrying in the wafer. Further, the SCH 25 transports a wafer from a wafer collection station (hereinafter referred to as RCV) 21 to be described later to an in-line unit 24 that is a carry-in source or an open cassette placed in the open cassette elevator 20. In PA26, positioning is performed roughly. A wafer feeding hand (hereinafter referred to as SH) 23 conveys the wafer from the PA 26 to the wafer chuck at the supply position. After a series of processing is performed on the wafer stage, the wafer (chuck) moves to the collection position. A wafer collection hand (hereinafter referred to as RH) 22 moves the wafer at the collection position to the RCV 21.

  FIG. 3 shows a wafer transfer sequence in the transfer system. A wafer placed on the inline unit 31 from the coater / developer 30 or an open cassette placed on the open cassette elevator 40 is transferred to the PA 33 by the SCH 32. Subsequently, the wafer in the PA 33 is transferred to the delivery pins 37 waiting at the supply position by the SH 34. After that, the chuck 36 sucks and performs positioning with higher accuracy on the exposure stage, and exposure processing is performed after some calibration measurement and correction such as focus are performed on the stage.

  After completion of the exposure, the wafer in the chuck 36 waiting at the collection position is transferred to the transfer pin 37, and is transferred to the RCV 39 by the RH 38. Subsequently, the wafer in the RCV 39 is transferred by the SCH 32 to the inline unit 31 which is the carry-in source or the open cassette in the open cassette elevator 40, and the normal transfer sequence inside the exposure apparatus is completed.

An example of the proposed function will be described with respect to the case where trouble occurs in the exposure apparatus in the above-described configuration and the wafer existing on the wafer stage is unloaded together with the reset process of the apparatus.
In collecting the wafer, first, in order to determine whether or not the wafer can be unloaded, the suction state of the wafer is confirmed. At this time, the delivery pin 37 on the wafer stage 35 has an air suction function.

  As a procedure for confirming the suction state, first, the suction state is confirmed by the delivery pin 37. Specifically, it is confirmed by measurement that the vacuum air pressure is equal to or lower than a predetermined pressure. Subsequently, the chucking state is similarly used to confirm the suction state. At this time, if there is no problem in the confirmation using the delivery pins 37 and the chuck 36, it is determined that the posture of the wafer is normal and the wafer is transferred as it is. On the other hand, if there is a problem in both suction states, it is difficult to carry it as it is, so confirm the posture using a camera etc. Measurement / correction shall be performed.

In this embodiment, when the wafer is displaced, it is assumed that the suction by the transfer pin 37 is possible but the chuck 36 cannot. The reason is that the wafer is usually deformed into a bowl shape due to heat during various processes. In this case, since the curvature becomes larger as it is closer to the outer periphery of the wafer, the chucking at the outer peripheral portion by the chuck 36 is more difficult than the chucking at the central portion by the transfer pins 37.
At this time, the fact that the wafer is attracted by the delivery pins 37 means that the wafer is on the delivery pins 37 and the wafer can be transported with a low risk of dropping in the sucked state. Therefore, when the suction by the delivery pin 37 is possible and the suction by the chuck 36 is not possible, it is determined that the transport is possible and the measurement process described later is performed.

  Depending on the deformation state of the wafer (when the outer peripheral portion is flat and the central portion has irregularities), the opposite result can be considered. In this case as well, the chuck 36 can adsorb the wafer on the chuck 36 and can carry the wafer with no risk of dropping in the sucked state. Therefore, even when the chuck 36 can be sucked and the transfer pin 37 cannot be sucked, it is determined that the chuck can be transported, and a measurement process described later is performed.

  FIG. 4 is a schematic diagram of the focus measurement system used in this embodiment. Measurement light (LED light) is introduced from the LED box 41 to the light projecting unit 43 via the optical fiber 42 prepared for each channel. The measurement light emitted from the light projecting unit 43 is reflected by the surface of the measurement shot 45 of the wafer 44 and measured by the light receiving unit 46. At this time, the reference light simultaneously emitted from the light projecting unit 43 is measured by the light receiving unit 46, and the focus amount (height information) is calculated from the phase difference (positional difference) between them.

  In this embodiment, the sensor is used to measure several points on the outer periphery of the wafer at equal intervals as shown in FIG. 5 to calculate the wafer position. For example, if O1 cannot be measured, it can be seen that the wafer is displaced in the direction of the vector connected from O1 toward the center of the wafer. Further, when O2 and O8 can be measured at this time, the wafer shift amount (range) can be calculated by the method described below.

A method of calculating the deviation amount will be described. The axes on the measurement points are determined as OX (1, 2,..., N) and OY (1, 2,..., M) from the upper left. Then, the observation interval for the vertical shift on FIGS. 5 and 6 is defined by OY (M) to OY (M + 1), and the degrees of freedom of x and y (δMx, δMy) between the observation point on the axis and the wafer periphery. Is indefinite. At this time, the amount is the accuracy (resolution) of wafer posture estimation.
As will be described later, the number of observation points is determined by a trade-off with the required accuracy because the measurement resolution increases as the number of points increases. Further, although the observation points are arranged at equal intervals in the figure, if there is directivity in measuring the deviation, it is also possible to perform measurement with a locally increased number of measurement points.

  The observation point coordinates when the number of observation points is p can be expressed as follows. At this time, i is numbered in the clockwise order, with the point at the position of 0 (12) being the first.

ここで、ｄｐはウエハ外周からのオフセット距離であり、該距離を設ける場合はウエハエッジからＯＹ（１）までが観測区間となる。例えば、Ｏ１が計測できない場合は少なくとも距離ｄｐ分だけずれていることが分かる。
この観測点を通るようなｘｙ方向の軸ＯＸ、ＯＹは次式で表される。
（イ）奇数個の観測点が計測できない場合（図５の垂直方向）

Here, dp is an offset distance from the outer periphery of the wafer, and when the distance is provided, the observation section is from the wafer edge to OY (1). For example, when O1 cannot be measured, it can be seen that the distance is shifted by at least the distance dp.
The axes OX and OY in the xy direction passing through this observation point are expressed by the following equations.
(B) When an odd number of observation points cannot be measured (vertical direction in Fig. 5)

（ロ）偶数個の観測点が計測できない場合（図６の垂直方向）
この場合は、図５の絶対座標を反時計回りにπ／ｐ度回転させて考える。すなわち

(B) Even number of observation points cannot be measured (vertical direction in Fig. 6)
In this case, the absolute coordinates in FIG. 5 are considered counterclockwise by rotating π / p degrees. Ie

  Next, an indefinite area for each observation section is defined. In either case (b) or (b), considering in one direction, it can be considered that the other direction is in a rotated state. The observation section M is defined by the Y axes OY (M) to OY (M + 1), and the number of sections is (A) M = 1, 2,..., (P / 2 + 1), (B) M = 1, 2, ..., (p / 2). The indefinite amount is the amount of wafer misalignment that can occur when the wafer can no longer be detected at the observation point O on OY (M) in the observation section M and can be observed on OY (M + 1).

The calculation of these quantities will be described. First, a circle having a radius r passing through the axes OY (M) and OY (M + 1) of the measurement section M is obtained. r is a wafer radius (150 [mm] for a 12-inch wafer and 100 [mm] for an 8-inch wafer), and the centers of the two circles obtained at this time are CM and CM + 1, respectively. Then, the indefinite amount (δMx, δMy) is expressed by the following formula.
δMx = Min (distance A, distance B)
Here, the distance A is a distance between “an intersection of a circle having a radius r and a center (0, δMy) and OY (M)” and “an observation point in the same quadrant (nearby) on the same axis”. The distance B is a distance between “an intersection of a circle having a radius of r and a center of (0, δMy) and OY (M + 1)” and an “observation point on the same quadrant (nearby) on the same axis”.
At this time, δMy is CM <δMy <CM + 1, and the distance A and the distance B can be expressed by the following equations.

なお、実際には、これらの不定量は特定することができないため、該値の最大量（ΔＭｘ，ΔＭｙ）が修正可否判断の対象量となる。該最大量は以下の式で表せる。

Actually, since these indefinite amounts cannot be specified, the maximum amount (ΔMx, ΔMy) of the values is a target amount for determining whether correction is possible. The maximum amount can be expressed by the following formula.

この方程式はマクローリン展開を用いて近似的に解くか、あるいは、Ｙを一定量ずつ変化させ、Ａ−Ｂ＞０となった時点でのＹを解とする数値計算的な解法を用いて解くことができる。
求まった不定最大量（ΔＭｘ，ΔＭｙ）はずれの範囲を表し、先述したように算出するズレ量の精度となる。したがって、該範囲よりも小さい精度で姿勢を修正する場合は、過修正してしまう可能性があるため、確認・再駆動という追い込み処理が必要となる。
ウエハのずれ量は、各区間で不定最大量（ΔＭｘ，ΔＭｙ）を対象となる区間で総計した量となる。

This equation can be solved approximately using the macrolin expansion, or it can be solved using a numerical calculation method in which Y is changed by a certain amount and Y is the solution when AB> 0. Can do.
The obtained indefinite maximum amount (ΔMx, ΔMy) represents the range of deviation and becomes the accuracy of the amount of deviation calculated as described above. Accordingly, when the posture is corrected with an accuracy smaller than the range, there is a possibility that the posture is overcorrected.
The wafer shift amount is the sum of the indefinite maximum amount (ΔMx, ΔMy) in each section in each section.

また、ずれの方向は、計測できなかったポイント（以下、計測不可点）の位置とウエハの中心の関係から算出する。このとき、通常計測できないポイントは円周上に連続して存在するはずであり、もし、不連続な計測不可点が計測された場合には、計測エラーとして処理を中止するか、再計測を行う。

Further, the direction of deviation is calculated from the relationship between the position of a point that could not be measured (hereinafter, a point that cannot be measured) and the center of the wafer. At this time, the points that cannot be measured normally should exist continuously on the circumference. If a discontinuous measurement impossible point is measured, the process is canceled as a measurement error or remeasurement is performed. .

  In the procedure for calculating the direction of deviation, the center position value P of consecutive unmeasurable points on the circumference is obtained and a vector is connected from the position P to the wafer center O. At this time, the direction indicated by the vector represents the direction of deviation. However, the direction obtained at this time is an estimated value of the direction at the resolution depending on the number of measurement points, and means an average direction of deviation including the above-described indefinite amount of deviation.

Note that when the number of unobserved points is an odd number, P is the center point of consecutive unobserved points. When there are an even number of unobserved points, P is the center position of the shortest arc connecting consecutive unobserved points. For example, assuming that the center of the wafer is O0 in FIG. 5, if O1 cannot be measured, a vector connecting O1 and the center O0 is an estimated direction, and if O1, O2, and O3 cannot be measured, a vector connecting O2 and O0 is estimated. Direction. Further, when O1 and O2 cannot be measured, a vector connecting O1.5 and O0 is an estimated direction with O1.5 being the center position of the shorter arc of the arcs connecting O1 and O2.
Furthermore, since focus information is obtained for the measurable points, it is possible to calculate an approximate value of the tilt amount of the wafer surface using the least square method or the like based on the height information.

The wafer displacement amount, the displacement direction, and the inclination amount obtained above are compared with an allowable amount previously input to the apparatus, and if it is less than a threshold value (allowable amount), it is determined that the wafer can be transferred. Do. In this embodiment, when it is determined that the wafer can be transported, the wafer on the wafer stage 35 is transported to the RCV 39 by the RH 38 and transported to the in-line unit 31 that is the transport source or the open cassette on the open cassette elevator 40 by the SCH 32.
Note that the wafer displacement estimated amounts Dx and Dy corresponding to the measurement section can be calculated in advance, and at the time of measurement, the measurement impossible points can be obtained and the corresponding amounts can be referred from the storage device. .

The threshold values are a shift amount, a shift direction, and a tilt, and values are set and stored from the operation screen of the exposure apparatus, or values are set and stored from the host server via online communication.
For example, in this embodiment, it is assumed that the allowable amount when placed in an in-line station is the smallest on the transport path, and the horizontal (x, y) margins are input and stored as the allowable deviation amount. For the allowable tilt amount, the average value m of the tilt on the stage and the standard deviation σ are measured, and m ± 3σ is input and stored. Then, based on the estimated deviation amount and the estimated direction calculated above, the deviation amount in the x and y directions of the wafer center is calculated, and the three amounts including the inclination are compared. At this time, if all of the amounts are within the allowable range, unloading is automatically performed. Otherwise, it is determined that the conveyance is impossible, and the status is notified through the screen of the apparatus or online communication.

  At this time, even if the state is equal to or greater than the threshold value, the wafer can be corrected with a deviation if it can be shifted to a position symmetrical with respect to the center of the wafer with respect to the posture calculated in the transfer portion. Can be transported. Therefore, even when the allowable amount is exceeded, it is possible to carry in a form in which the deviation is corrected.

[Example 2]
In the second embodiment, the semiconductor exposure apparatus, the transfer system, and the focus system to which the present invention is applied are the same as those described in the first embodiment. Further, the position correction and transfer after obtaining the wafer position by the method described below are the same as those in the first embodiment.
In the present embodiment, using the sensor shown in FIG. 4, three measurement lines near the wafer outer periphery are determined as shown in FIG. 7, and focus measurement is performed at a constant interval within a predetermined range. At this time, since the wafer edge position can be determined depending on whether focus measurement is possible, the wafer position information is calculated based on the coordinate information of the three wafer edges. Further, the tilt information of the wafer surface is calculated based on the focus information obtained at the measured points.

A method for calculating position information will be described. First, assuming three vertical lines from the chuck center (the center of the wafer in a normal posture) to the circumference, a certain measurement range is determined from the edge of the wafer in the normal posture. At this time, the range is determined by the driving limit of the wafer stage and the clearance on the transfer path.
Focus measurement is performed at predetermined measurement points on the above three measurement lines. At this time, since the interval corresponds to the accuracy of the position information to be obtained, it is determined in view of the trade-off between the required accuracy and the measurement time. In the figure, the measurement is performed at a constant interval. However, when a tendency (distribution) is observed in the amount of wafer displacement, the measurement may be performed while changing the interval.

In the measurement on the line, the measurement points are sequentially measured as shown in the figure, and the wafer edge position (x, y) at which the focus can be measured first is obtained. In this example, the positions (x _A , y _A ), (x _B , y _B ), and (x _C , y _C ) are measured with three measurement lines. When the wafer edge is obtained, it is not always necessary to measure the subsequent measurement points. However, all the measurement points inside the wafer may be measured in order to improve the calculation accuracy of the wafer tilt.

Since the equation of the circle is expressed as follows, the above three points (x _A , y _A ), (x _B , y _B ), (x _C , y _C ) are substituted, and the coefficient position (a, b) Further, by obtaining the radius r, it is possible to estimate the wafer position.
(X−a) ² + (y−b) ² = r ²
At this time, r is a wafer radius (150 [mm] for a 12-inch wafer and 100 [mm] for an 8-inch wafer).
Further, based on the focus information on the wafer measured as described above, the amount of tilt of the wafer is calculated based on the minimum two pieces of information.
If the measurement interval is Δ, the distance from the wafer center to the wafer edge

に対してΔの誤差が生じる。つまり計測により算出されるウエハの位置は（ａ＋Δ，ｂ＋Δ）となるため、要求精度に応じてΔを設定するものとする。
また、本例では３つの計測ライン（ウエハエッジ）を計測しているが、Δを図４のセンサの計測精度以下に設定した場合は、更に多くのラインを計測して最小２乗法を用いて位置情報の算出精度を高めることも可能である。

Δ error occurs. That is, since the wafer position calculated by measurement is (a + Δ, b + Δ), Δ is set according to the required accuracy.
In this example, three measurement lines (wafer edges) are measured. However, when Δ is set to be equal to or lower than the measurement accuracy of the sensor shown in FIG. 4, more lines are measured and the position using the least square method is measured. It is also possible to improve the calculation accuracy of information.

In the first and second embodiments described above, one measurement value (channel) of the focus sensor is used. However, when measurement is possible with multiple channels, these measurement values can be included in the calculation.
As another embodiment, it is also possible to use an alignment scope 5 and an image sensor for performing alignment measurement instead of the focus sensor. However, in this case, since focus information cannot be obtained, the wafer shift and the shift direction are calculated.

[Example 3]
Next, a manufacturing process of a microdevice (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.) using the above-described exposure apparatus will be described.
FIG. 8 shows a flow of manufacturing a semiconductor device.
In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask production), a mask (also referred to as an original plate or a reticle) on which the designed pattern is formed is produced.
On the other hand, in step 3 (wafer manufacture), a wafer (also referred to as a substrate) is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the wafer and the exposure apparatus provided with the prepared mask.
The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer manufactured in step 4. The post-process includes assembly processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.

  The wafer process in step 4 includes an oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, and an electrode formation step for forming electrodes on the wafer by vapor deposition. Also, an ion implantation step for implanting ions into the wafer, a resist processing step for applying a photosensitive agent to the wafer, and an exposure step for exposing the wafer after the resist processing step through a mask having a circuit pattern using the exposure apparatus described above. Have. Further, there are a development step for developing the wafer exposed in the exposure step, an etching step for removing portions other than the resist image developed in the development step, and a resist stripping step for removing the resist that has become unnecessary after the etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

It is a figure which shows the structure of the exposure apparatus which concerns on one Example of this invention. It is a figure which shows the structure of the wafer conveyance system in the apparatus of FIG. It is a figure which shows the outline | summary of the conveyance sequence of the wafer in the apparatus of FIG. It is a figure which shows the outline | summary of the focus measurement system in the apparatus of FIG. It is a figure explaining the example of a measurement (deviation in the direction of a measuring point) in the device of FIG. It is a figure explaining the example of a measurement (deviation in the middle direction of a measurement point) in the device of FIG. It is a figure explaining the other example of a measurement in the apparatus of FIG. It is a figure explaining the flow of the manufacturing process of a device.

Explanation of symbols

5 Alignment scope 6, 43 Focus detection system (light emitting part)
7, 46 Focus detection system (light receiving unit)
8 Wafer 9, 36 Chuck 20, 40 Open cassette elevator 21, 39 Wafer collection station (RCV)
22, 38 Wafer collection hand (RH)
23, 34 Wafer feeding hand (SH)
24, 31 Inline unit 25, 32 Wafer carry-in hand (SCH)
26, 33 Pre-alignment unit (PA)
30 Coater / developer 35 Wafer stage 37 Transfer pin

Claims (12)

Measuring the position of the target area on the surface of the substrate held on the stage, and a stage for sucking and holding the substrate, transferring the substrate between the stage and transferring the substrate, and transporting the substrate An exposure apparatus that exposes the substrate by moving the stage based on the measured position,
Whether the suction state of the substrate by the stage is correct or not is determined, and when the suction state is abnormal, the amount of positional deviation of the substrate is measured using the measuring instrument, and according to the measured positional deviation amount An exposure apparatus, wherein the substrate is transferred between the stage and the transport unit.   The exposure apparatus according to claim 1, wherein the measuring instrument is a measuring instrument that measures the height of a target region on the surface of the substrate.   The exposure apparatus according to claim 1, wherein the measuring instrument is a measuring instrument that measures a position of an alignment mark on the substrate.   Determining the presence or absence of the surface of the substrate at each of a plurality of predetermined locations on the stage using the measuring instrument, and measuring the amount of displacement based on the determined presence or absence. An exposure apparatus according to any one of claims 1 to 3.   The position shift amount is measured based on the detected positions of at least three end portions of the substrate using the measuring device and detecting the positions of the at least three end portions of the substrate. The exposure apparatus according to any one of 1 to 4.   The exposure apparatus according to claim 1, wherein the positional deviation amount includes a positional deviation amount in a predetermined coordinate plane.   The exposure apparatus according to claim 1, wherein the displacement amount includes an inclination amount of the substrate.   It is determined whether or not the amount of positional deviation is within a predetermined allowable range, and when it is determined that the amount of positional deviation is within the allowable range, the substrate is moved between the stage and the transport unit. 8. The exposure apparatus according to claim 1, wherein the exposure is performed.   It is determined whether the positional deviation amount is within a predetermined allowable range, and when it is determined that the positional deviation amount is not within the allowable range, information related to the determination result is notified. An exposure apparatus according to any one of claims 1 to 8. The stage includes a chuck that sucks the substrate, and a delivery pin that can penetrate the chuck and suck the substrate,
The exposure apparatus according to claim 1, wherein when the substrate cannot be normally sucked by at least one of the chuck and the delivery pin, the suction state is determined to be abnormal.   The exposure apparatus according to claim 1, wherein the stage sucks the substrate by a vacuum, and whether the suction state is correct is determined based on the pressure of the vacuum. Exposing the substrate using the exposure apparatus according to claim 1;
Developing the exposed substrate. A device manufacturing method comprising:

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