JPH09320948A - Substrate transfer method and exposure apparatus - Google Patents

Abstract

(57) Abstract: It is possible to reliably suppress the occurrence of positional displacement of a substrate when the substrate is transferred to a substrate holder. SOLUTION: When a substrate W is held by a transfer arm (not shown in FIG. 3) and transferred to a transfer position, the inclination of the substrate transferred to this transfer position is measured by a measuring means (52).
A, 52B, 52C, 52D), and the inclination of the substrate holder 34 is adjusted so that the contact surface of the substrate holder 34 with the substrate becomes parallel to the substrate W based on the measurement result. 56 descends to the substrate W
Are placed on the substrate holder 34. Therefore, before the substrate is transferred to the substrate holder, the difference between the inclination angle of the substrate contact surface of the substrate holder and the inclination angle of the substrate is forced to zero, and the substrate at the time of the transfer to the substrate holder due to this angle difference. It is possible to reliably prevent the occurrence of the positional deviation of the.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate transfer method and an exposure apparatus, and more particularly to a substrate transfer method for transferring a substrate to a substrate holder provided on a stage and exposure using the transfer method. The present invention relates to an exposure apparatus that transfers a photosensitive substrate such as a wafer or a glass plate as a substrate to a substrate holder at the top of the stage section.

[0002]

2. Description of the Related Art Conventionally, in a photolithography process in manufacturing a semiconductor device or a liquid crystal display substrate, a pattern of a mask (reticle) is projected and exposed through a projection optical system onto a wafer, a glass plate or the like coated with a photosensitive material. Various projection exposure apparatuses are used. For example, in a semiconductor element manufacturing process, a reduction projection type exposure apparatus such as a stepper, which sequentially projects and exposes a reticle pattern onto each shot area on a wafer through a reduction projection lens, is mainstream as the density of semiconductor integrated circuits increases. Has become.

FIG. 11 shows constituent parts of a wafer transfer mechanism of a projection exposure apparatus of this type. In this figure, the wafer transfer mechanism includes a substrate table (leveling table) 90 that can be vertically moved and tilted by a drive system (not shown), and the substrate table 9.
0 and a stepped columnar component (hereinafter, referred to as “center up”) 94 that can move up and down relative to a wafer holder 92 on the substrate table 90. This will be described in further detail.
2 is inserted into the central opening 92A and the central opening of the substrate table 90 through a predetermined clearance, and the uppermost surface thereof is provided with a contact portion with a single or a plurality of wafers W. At the contact portion, the wafer W can be adsorbed and fixed by the suction force of a vacuum pump connected through a pipe (not shown). The center-up 94 is vertically movable by a drive mechanism 98 arranged on an XY stage (not shown).

Here, referring to FIG. 11, a brief description will be given of how the wafer W is transferred to the wafer holder 92. The wafer W is transferred above the XY stage by a transfer arm of a wafer loader (not shown). Then, the center-up 94 raises the wafer W held by the transfer arm from above to slightly above the wafer holding surface of the transfer arm, and performs the operation of temporarily receiving the wafer.
FIG. 11 shows the state at this time. Next, after the transfer arm retracts, the center-up 94 descends to a height at which the wafer W contacts the upper surface of the wafer holder 92,
As a result, the wafer W is delivered to the upper surface of the wafer holder.

[0005]

By the way, when an attempt is made to deliver the wafer W to the upper surface of the wafer holder 92 using the above-mentioned wafer delivery mechanism, in reality, a slight positional deviation often occurs. The cause of this positional deviation is the flatness of the wafer W and the wafer holder 92.
Of course, the uppermost wafer supporting surface of the center-up 94 and the upper surface of the wafer holder 92 are not parallel to each other. Therefore, the inclination angles of the two are different, and the angle error θ as shown in FIG. In some cases this has proven to be a major cause. According to the experiments by the present inventors,
When the tilt angle error θ between the center-up wafer supporting surface and the wafer holder upper surface is about 10 minutes, 0.1
It has been found that a large positional deviation of about mm occurs.
The positioning accuracy required for the projection exposure apparatus at the time of exposure is now on the order of nanometers (nm), and therefore the positional deviation allowed during wafer transfer is on the order of microns (μm) due to the restriction of the measurement range of the positioning optical sensor. Has become. Therefore, it is clear that the occurrence of displacement of 0.1 mm or more is no longer acceptable.

The present invention has been made under such circumstances, and an object thereof is to provide a substrate transfer method capable of reliably suppressing the occurrence of displacement of the substrate when transferring the substrate to the substrate holder, and a method for transferring the substrate. An object is to provide an exposure apparatus to which the method is applied.

[0007]

According to a first aspect of the present invention, there is provided a substrate transfer method for transferring a substrate to a substrate holder provided on a stage, the substrate being transferred to a predetermined transfer position, and A first step of measuring a relative inclination with respect to the substrate holder; a second step of transporting the substrate to the delivery position; and a contact surface of the substrate holder with the substrate based on the measurement result of the first step. A third step of adjusting the inclination of at least one of the substrate transported to the delivery position and the substrate holder so as to be parallel to the substrate transported to the delivery position; and thereafter, the inclination of the substrate and the substrate holder. And a fourth step of placing the substrate on the substrate holder while maintaining the above condition.

According to this, in the first step, the relative inclination between the substrate and the substrate holder that are transported to the predetermined transfer position is measured, and in the second step, the substrate is transferred to the transfer position. In the third step, the inclination of the substrate holder is adjusted so that the contact surface of the substrate holder with the substrate is parallel to the substrate based on the measurement result of the first step, and then in the fourth step, the inclination of the substrate and the substrate holder is adjusted. The substrate is placed on the substrate holder while maintaining the inclination. Therefore, before the substrate is transferred to the substrate holder, the difference between the inclination angle of the substrate contact surface of the substrate holder and the inclination angle of the substrate is forced to zero, and the substrate at the time of the transfer to the substrate holder due to this angle difference. It is possible to reliably prevent the occurrence of the positional deviation of the substrate, and thereby to eliminate one factor that causes the positional deviation of the substrate when the substrate is transferred to the substrate holder.

Here, the measurement in the first step may be performed after the substrate is transported to the transfer position in the second step, as in the invention described in claim 2, or
As in the third aspect of the invention, the second step may be performed at the time of assembling and adjusting the substrate holder and the delivery mechanism for delivering the substrate to the substrate holder. When it is performed after the substrate is transferred to the delivery position, it is preferably performed every time the substrate is transferred to the delivery position. In this case, since the measurement is performed every time, even if the flatness of the substrate is changed, it can be dealt with. Further, in the case where the substrate holder and the transfer mechanism for transferring the substrate to the substrate holder are assembled and adjusted in advance, it is desirable to perform the measurement only once and store the measurement result in the memory. By doing so, the processing from the third step onward is performed using the measurement result stored in the memory, so that the throughput can be improved accordingly.

Further, when the measurement of the first step is performed in advance at the time of assembling and adjusting the substrate holder and the delivery mechanism for delivering the substrate to the substrate holder, the photoelectric collimator according to the invention as set forth in claim 4 is provided. Alternatively, it can be performed with a water bubble level.

According to a fifth aspect of the present invention, there is provided an exposure device which projects and exposes a pattern formed on a mask onto a photosensitive substrate through a projection optical system, and a stage movable in a two-dimensional plane; A substrate table mounted on a stage and capable of adjusting the movement of the projection optical system in the optical axis direction and an inclination with respect to the optical axis; a substrate holder mounted on the substrate table and mounting the photosensitive substrate; A transfer arm for transferring the photosensitive substrate to a predetermined transfer position; a transfer means for transferring the photosensitive substrate between the transfer arm and the substrate holder; a measuring means for measuring the inclination of the photosensitive substrate; Each time the photosensitive substrate is transferred to the substrate holder, the inclination of the photosensitive substrate is measured using the measuring means during the transfer, and based on the measurement result. Contact surface with the substrate of the serial substrate holder and a control means for adjusting the tilt of the substrate table so as to be parallel with the photosensitive substrate.

According to this, when the substrate is transferred to the transfer position by the transfer arm, the substrate table moves together with the stage to a position where the substrate can be transferred to the substrate holder, and the transfer means transfers the substrate from the transfer arm to the substrate holder. The photosensitive substrate is delivered. Every time the transfer means transfers the photosensitive substrate to the substrate holder, the control means measures the inclination of the photosensitive substrate using the measuring means during the transfer, and contacts the substrate holder with the substrate based on the measurement result. The tilt of the substrate table is adjusted so that the surface is parallel to the photosensitive substrate. Therefore, before the substrate is transferred to the substrate holder, the difference between the inclination angle of the substrate contact surface of the substrate holder and the inclination angle of the substrate is forced to zero, and the substrate at the time of the transfer to the substrate holder due to this angle difference. It is possible to reliably prevent the occurrence of the positional deviation of the substrate, and thereby to eliminate one factor that causes the positional deviation of the substrate when the substrate is transferred to the substrate holder.

According to a sixth aspect of the invention, in the exposure apparatus according to the fifth aspect, the inclination of the photosensitive substrate is measured only once in advance by using the measuring means instead of the control means, and the exposure is performed. Each time the substrate is transferred to the substrate holder, the inclination of the substrate table is tilted by using the result of the tilt measurement so that the contact surface of the substrate holder with the substrate becomes parallel to the photosensitive substrate during the transfer. A second control means for adjusting is provided.

According to this, the second control means uses the measuring means to measure the inclination of the photosensitive substrate only once in advance,
Every time the photosensitive substrate is transferred to the substrate holder, the inclination of the substrate table is adjusted using the result of the inclination measurement so that the contact surface of the substrate holder with the substrate becomes parallel to the photosensitive substrate during the transfer. The throughput can be improved as compared with the invention described in claim 2, in which the measurement is performed every time the photosensitive substrate is transferred to the substrate holder.

In the exposure apparatus according to claim 5 or 6,
The measuring means may be configured by a focus detection mechanism that detects the positions of the photosensitive substrate surface in the optical axis direction at a plurality of positions, or a direction oblique to the optical axis of the projection optical system on the photosensitive substrate surface. It may be configured by a leveling detection mechanism that irradiates a parallel light flux from the above and detects the inclination of the photosensitive substrate based on the light receiving position of the reflected light flux. In the latter case, there is an advantage that the inclination can be measured even if the photosensitive substrate is not necessarily near the focal plane of the projection optical system.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

<< First Embodiment >> A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an exposure apparatus 1 according to the first embodiment.
The overall configuration of 0 is shown schematically. This exposure apparatus 1
0 is a surface plate (anti-vibration table) 16 held on a pedestal 12 horizontally placed on the floor via four anti-vibration pads 14,
The stage device 20 arranged on the surface plate 16 and the first device 20 planted on the surface plate 16 above the stage device 20.
The column 18, the projection optical system PL held by the first column 18, and the first column 1 above the projection optical system PL.
Second column 22 planted in No. 8 and this second column 22
The reticle holder 24 is mounted on the reticle R for holding the reticle R as a mask, and the illumination system 26 is arranged above the reticle holder 24.

The stage device 20 is mounted on the surface plate 16 in the Y direction.
A Y stage 28Y movable in the axial direction (direction orthogonal to the paper surface in FIG. 1), an X stage 28X as a stage movable in the X axis direction orthogonal to the Y axis (lateral direction in the paper surface in FIG. 1), and a Y stage 28Y. , A drive system 29 for driving the X stage 28X in the respective moving directions, and a vertical tilting mechanism 30 mounted on the X stage 28X.
And a substrate table 32 driven by the vertical tilting mechanism 30 in the Z-axis (vertical axis) direction orthogonal to the XY plane and in the rotational directions around the X-axis and the Y-axis.

A wafer holder 34 is mounted on the substrate table 32 via a θ table (not shown), and a wafer W as a photosensitive substrate is adsorbed and fixed on the wafer holder 34. Further, a movable mirror 36 constituting a laser interferometer system is fixed to an end of the substrate table 32,
The laser interferometer 38 is used to measure the position coordinates of the substrate table 32 in the XY two-dimensional directions, that is, the XY coordinates of the shot area on the wafer W via the movable mirror 36. Actually, as shown in the schematic plan view of FIG. 2, the Y-axis moving mirror 36Y extended in the X-axis direction.
And an X-axis moving mirror 36X extending in the Y-axis direction, and a Y-axis laser interferometer 38Y and an X-axis laser interferometer 38X corresponding thereto are present. Then, these are typically shown as a moving mirror 36 and a laser interferometer 38.

The reticle holder 24 can be finely driven in the XY two-dimensional directions and the θ direction (rotational direction around the Z axis) by the drive system 25.
When aligning the reticle R held by the reticle R, the center of the pattern surface of the reticle R (reticle center) is aligned with the optical axis of the projection optical system PL via the drive system 25 in the XY plane. Is adjusted.

The projection optical system PL is held by the first column 18 in a state in which its optical axis is in the Z-axis direction orthogonal to the XY plane. As the projection optical system, here, both sides are telecentric and predetermined. Reduction ratio (for example, 1/4)
Are used. Therefore, with the reticle R and the wafer W aligned, the illumination system 26
When the reticle R is illuminated with the illumination light from, the reduced image of the pattern drawn on the pattern surface of the reticle R is transferred to the shot area on the wafer W.

FIG. 2 is a schematic plan view of the exposure apparatus 10 with the upper plate of the first column 18 and the components above the upper plate removed. As shown in FIG. 2, an X-axis guide 42 extending in the X-axis direction is arranged on the front side (lower side in FIG. 2) of the first column 18, and the front side of the X-axis guide 42 is further forward. Two wafer cassettes 44 are arranged in the. A Y-axis guide 46 is provided orthogonally to the X-axis guide 42, and the Y-axis guide 46 is provided by a wafer loader drive system (not shown).
It is designed to be driven along the line 2. Y-axis guide 4
6 is a transfer arm for wafer loading (load arm)
A transfer arm 48A and a transfer arm (unload arm) 48B for unloading the wafer are provided so as to be movable along the Y-axis guide 46. These load arm 48A and unload arm 48B are also driven by a wafer loader drive system (not shown). In this case,
From the moving surface of the unload arm 48B, the load arm 48
The moving surface of A is set at a higher position. this is,
This is for the purpose of avoiding the inconvenience of dust and the like adhering to this resist as much as possible because the higher position has less dust and the like floating in the atmosphere in the air and the resist on the wafer surface is not solidified before exposure.

On the upper surface of the load arm 48A, as shown in FIG. 2, a pair of adsorption portions 5 for adsorbing the wafer W.
0 is provided, and a U-shaped cutout is formed in a portion between the pair of suction portions 50. This notch is formed so that the center-up does not interfere with the load arm 48A when the wafer W is transferred to the center-up described later.

In this embodiment, the X-axis guide 42, the Y-axis guide 46, the load arm 48A, and the unload arm 48.
B and a wafer loader drive system (not shown) carry the wafer W from the outside to a predetermined transfer position (a predetermined position within the moving range of the substrate table), and
A wafer loader is configured as a wafer transfer mechanism that receives the exposed wafer W at the delivery position and carries it out to the outside. In FIG. 1, the load arm 48A and the unload arm 48B are typically shown as the transfer arm 48.

Further, in the exposure apparatus 10 of the present embodiment, the wafer W that is suction-fixed to the wafer holder 34 during the exposure process.
The leveling detection mechanism (leveling sensor) 52 is used as a measuring means for measuring the inclination of the shot area of the wafer W or for measuring the inclination angle of the surface (upper surface) of the wafer W held in the center-up which constitutes the wafer vertical movement mechanism described later. It is provided (see FIG. 1). The specific configuration, operation, etc. of the leveling sensor 52 will be described later.

FIG. 3 shows a schematic structure of the wafer vertical movement mechanism and the leveling sensor 52. In FIG. 3, the wafer up-and-down moving mechanism drives the center-up 56, which includes a substrate table 32 and a stepped columnar component that can move up-and-down relative to the wafer holder 34 on the substrate table 32, and the center-up 56. It is composed of a center-up drive mechanism 58. More specifically, the center-up 56 is inserted through a predetermined clearance into the central opening 34A of the wafer holder 34 and the central opening of the substrate table 32.
The center-up drive mechanism 58 is the X stage 28X.
Is fixed to the uppermost surface of the motor 58A and this motor 58A
And a conversion mechanism for converting the rotational movement of the above into the linear movement of the center-up 56. Therefore, the center-up 56 can move up and down relatively to the wafer holder 34 and the substrate table 32 and independently of them. In other words, the substrate table 32 is also not restricted by the center-up 56 and can freely tilt. Similar to the conventional example described above, a contact portion with one or a plurality of wafers W is provided on the uppermost surface of the center-up 58, and this contact portion has a vacuum connected through a piping system (not shown). The wafer W can be sucked and fixed by the suction force of the pump.

The leveling sensor 52 is, for example, as shown in FIG. 3, a light source 52A and a collimating lens 52.
B, a condenser lens 52C, and a position detector 52D including a four-division light receiving element and the like. According to this, as shown in FIG. 3, the illumination light from the light source 52A is converted into parallel light by the collimator lens 52B, and this parallel light travels on the optical axis inclined by a predetermined angle with respect to the Z axis, and the wafer It is reflected by the W surface, and this reflected light beam forms an image on the light receiving surface of the position detector 52D via the condenser lens 52C. Therefore,
Since the image forming position on the light receiving surface of the position detector 52D is shifted according to the inclination of the surface of the wafer W, the amount of inclination (rolling amount, pitching amount) of the surface of the wafer W is obtained from the information of the image forming position.
You can know As described above, in the exposure apparatus 10 of the present embodiment, the leveling sensor 5 utilizing the principle of the collimator is used as the measuring means for measuring the tilt angle of the wafer surface.
Since No. 2 is adopted, the tilt angle can be measured even if the surface of the wafer W does not necessarily match the focal plane of the projection optical system PL.

FIG. 4 shows the configuration of a control system related to the delivery of the wafer W of the exposure apparatus 10 described above. This control system consists of a CPU (central processing unit), ROM, RAM
The main control unit 60 is mainly composed of a microcomputer (or a minicomputer) including the above, and the X-axis laser interferometer 38X, Y interferometer is provided on the input side of the main control unit 60. 38Y, the leveling sensor 52, etc. are connected. The main controller 60
The output side of the drive system 29, the vertical tilting mechanism 3
0, a center-up drive mechanism 58, a wafer loader control system 62 for controlling the wafer loader drive system described above, and a light source 5.
A light source switch (light source SW) 64 for turning the 2A on and off is connected.

Next, the operation of transferring the wafer W to the wafer holder 34 will be described based on the flowchart of FIG. 5 showing the main control algorithm of the CPU in the main controller 60.

First, in step 100, after instructing the wafer loader control system 62 to supply a wafer, the process proceeds to step 102 to wait until the wafer W is transferred to a predetermined delivery position.

The wafer loader control system 62 receives the wafer supply command and drives the load arm 48A and the Y-axis guide 46 through the wafer loader drive system to drive the wafer cassette 4.
The wafer W is taken out from the No. 4 by the load arm 48A and is transferred to a predetermined delivery position.

When the wafer W is transferred to the delivery position, the determination at step 102 is affirmative, and the routine proceeds to step 104, where the X stage 28X and the Y stage 28Y are driven to move the substrate table 32 to the delivery position. The positioning of the substrate table 32 during this movement is performed by controlling the drive system 29 while monitoring the measurement values of the laser interferometers 38X and 38Y. Here, the main controller 60 may monitor the position of the load arm 48A to determine whether or not the wafer W has been transferred to the delivery position, but a transfer completion command is received from the wafer loader control system 62. Thus, the command may be performed based on this command.

The substrate table 32 to the transfer position
May be performed prior to the transfer of the wafer W to the delivery position, or may be performed simultaneously with this operation.

In the next step 106, the center-up drive mechanism 58 is used to drive the center-up 56 upward. As a result, the center up 56 rises and the wafer W held by the load arm 48A of the wafer loader is moved.
Hold from below. At this time, the suction of the wafer W by the suction portion 50 of the load arm 48A is released, and at the same time when the wafer W is contacted, the suction of the wafer W by the contact portion of the center-up 56 is started.

In the next step 108, the load arm 4
Wait until 8A retracts to a position where it does not interfere with the stage device 20. The evacuation of the load arm 48A is started when the wafer loader control system 62 detects, for example, that the wafer W is separated from the load arm 48A via a sensor (not shown).

When it is confirmed that the load arm 48A has retracted to a position where it does not interfere with the stage device 20 based on the result of monitoring the position of the load arm 48A or the retract completion command from the wafer loader control system 62, the routine proceeds to step 110. , Center-up drive mechanism 5
The center up 56 is driven downward by a predetermined amount via 8.
This is because the leveling sensor 52 lowers the wafer W to a height at which the inclination of the surface of the wafer W can be measured.

In the next step 112, the leveling sensor 52 is used to measure the amount of inclination of the surface of the wafer W held by the center-up 56 before the wafer W is transferred to the wafer holder 34. In this measurement, the light source switch 64 is turned on, and the illumination light is emitted from the light source 52A of the leveling sensor 52 on the wafer W.
It is performed by irradiating the surface and calculating the tilt amount based on the output of the position detector 52D at this time.

In the next step 114, the above step 1
Wafer W based on the measurement result of the tilt amount in No. 12
So that the upper surface of the wafer holder 34 (contact surface with the wafer W) not in contact with is parallel to the wafer surface (that is, the difference θ between the inclination of the wafer surface and the upper surface of the wafer holder 34 is zero). The tilt of the substrate table 32 is adjusted via the vertical tilting mechanism 30. This allows
Before the wafer holder 34 receives the wafer W from the center-up 56, the difference in inclination angle between the upper surface of the wafer holder 34 and the wafer surface can be reduced to almost zero.

At the next step 116, the center-up drive mechanism 58 is used to drive the center-up 56 downwardly until the upper surface of the wafer holder 34 contacts the upper surface of the wafer W.
A series of control operations of this routine are finished. Thereafter, the suction of the wafer W by the center-up 56 is released, and at the same time, the suction of the wafer W by the wafer holder 34 is started, whereby the delivery of the wafer W to the wafer holder 34 is completed.

As is clear from the above description, in this embodiment, the delivery means is realized by the functions of the delivery mechanism including the center-up 56 and the center-up drive mechanism 58 and the main controller 60 that controls the delivery mechanism. The control means is realized by the function of the main controller.

As described above, according to the exposure apparatus 10 of the present embodiment, the difference θ in inclination angle between the upper surface of the wafer holder 34 and the wafer surface can be driven to almost zero immediately before the wafer W is transferred to the wafer holder 34. Therefore, it is possible to reliably prevent the occurrence of the positional deviation due to the angular difference θ when the wafer W is placed on the wafer holder 34, which causes the positional deviation between the wafer W and the wafer holder 34, and thus the wafer W. It is possible to reliably eliminate one of the factors that deteriorate the positioning accuracy during exposure of the upper shot area. Further, conventionally, the degree of parallelism between the upper surface of the center-up 56 and the upper surface of the wafer holder 34 is required to be considerably strict, and a design / manufacturing process that can achieve this has been unavoidable. Since it is possible to reduce the cost in designing / manufacturing, it is not necessary to have the severe accuracy related to the parallelism as in the conventional case.

<< Second Embodiment >> Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the same reference numerals will be used for the same or equivalent components as in the first embodiment described above, and the description thereof will be simplified or omitted.

The second embodiment is characterized in that a so-called oblique incident light type multi-point focal position detecting mechanism 70 is used as a measuring means in place of the leveling sensor 52 in the first embodiment. Have.

FIG. 6 shows a multipoint focal position detecting mechanism 70 as the measuring means of this embodiment together with a wafer up-and-down moving mechanism. The multi-point focus position detection mechanism 70 includes a light source 70A, a projection slit plate 70B, a projection lens (light transmitting optical system) 70C, a light receiving lens (light receiving optical system) 70D, a light receiving sensor 70E, and a light receiving slit plate (not shown). It is composed of. Optical axis of projection lens 70C and light receiving lens 70
The optical axis of D is symmetrical with respect to the Z axis (optical axis of the projection optical system PL). Here, a plurality of slits are formed in the projection slit plate 70B, and when the light from the light source 70A illuminates the projection slit plate 70B, images of these slits are transferred to the wafer W via the projection lens 70C.
An image is formed on the surface, and this image is re-imaged on a light-receiving slit plate (not shown) via the light-receiving lens 70D, and each image is formed by a light-receiving sensor (a plurality of photosensors provided corresponding to the slit images respectively). A defocus signal (defocus signal) corresponding to the position of each slit image on the surface of the wafer W in the Z-axis direction is output from each light receiving element. in this case,
Since the focus detection surface has the same structure as the focus surface of the projection optical system PL, the wafer W on the center-up 56 is
Should substantially coincide with the focal plane of the projection optical system PL.

The configuration of the other parts is the same as that of the main controller 60.
Is the same as that of the above-described first embodiment, except that the control algorithm is slightly different.

Next, the operation when the wafer W is delivered to the wafer holder 34 will be described based on the flowchart of FIG. 7 showing the main control algorithm of the CPU in the main controller according to the second embodiment.

In steps 200 to 208, the first
Since the same control operation as that of steps 100 to 108 in the above embodiment is performed, description thereof will be omitted.

In the waiting state of step 208, when the load arm 48A retracts to a position where it does not interfere with the stage device 20, the process proceeds to step 209 and the substrate table 32 is lowered by a predetermined amount while the wafer W is held by the center up 56. To drive. This is as mentioned above
In the case of the present embodiment, the wafer W on the center up 56
Since it is necessary to perform the measurement by the multipoint focus position detection mechanism 70 in a state in which is substantially matched with the focal plane of the projection optical system PL, the surface of the wafer W is projected for measuring the tilt amount of the surface of the wafer W described later. In order to prevent the wafer W from coming into contact with the upper surface of the wafer holder 34 while the center-up 56 is driven to descend near the focal plane of the optical system PL, the vertical tilting mechanism 30 is driven in advance to lower the substrate table 32. is there.

In the next step 210, the center-up drive mechanism 58 drives the center-up 56 downward by a predetermined amount to a height at which the tilt of the surface of the wafer W can be measured by the multi-point focus position detection mechanism 70.

In the next step 212, the tilt amount of the surface of the wafer W held by the center-up 56 before the transfer to the wafer holder 34 is measured by using the multipoint focus position detection mechanism 70. In this measurement, the light source switch of the multipoint focal position detection mechanism 70 is turned on, the projection slit plate 70B is illuminated by the illumination light from the light source 70A, and a plurality of slit images are formed on the surface of the wafer W by the projection lens 70C. Based on the focus signal corresponding to each slit image position obtained by receiving the light flux of each slit image by the light receiving sensor 70E via the light receiving lens 70D, at least 3 on the surface of the wafer W
This is performed by obtaining position information in the Z-axis direction of a portion and performing statistical processing such as the least-squares method using these position information to calculate the approximate surface and its inclination.

In the next step 214 and thereafter, the same control operation as in step 114 and thereafter is carried out to complete the transfer of the wafer W to the wafer holder 34.

According to the second embodiment described above,
Center up 5 by the processing of steps 212 and 214
Before the wafer holder 34 receives the wafer W from 6, the difference in the inclination angle between the upper surface of the wafer holder 34 and the wafer surface can be reduced to almost zero, so that the wafer W is placed on the wafer holder 34 as in the first embodiment. It is possible to reliably prevent the occurrence of positional deviation due to the difference θ in the tilt angle between the upper surface of the wafer holder 34 and the wafer surface when the wafer W is mounted, and thus the positioning accuracy of the shot area on the wafer W during exposure is deteriorated. It is possible to reliably eliminate one of the factors, and it is possible to reduce the design and manufacturing costs.

In the first and second embodiments described above, the case where the inclination amount of the surface of the wafer W is measured every time the wafer W is transferred to the center-up 56 has been described. The control algorithm of the main control device 60 is not limited, but measurement is performed only once when the device is assembled / started up, and the measurement result is shown in RA (not shown).
An algorithm which is stored in M and used as a device constant may be adopted. In this case, the second control means is realized by the function of the main control device 60, and steps 112 and 212 of the above-described flowchart are performed.
The processing can be omitted, and the throughput can be improved accordingly. However, in this case, the tilt amount adjustment of the substrate table 32 in steps 114 and 214 is performed based on the device constant stored in the RAM.

Further, the inclination of the wafer transferred to the transfer position and the relative inclination measurement of the wafer holder are measured by using a highly versatile inclination measuring means such as a photoelectric collimator or a water bubble level, and a substrate is placed on the wafer holder and the wafer holder. A mechanism for delivering, for example, performing only once in advance during center-up assembly adjustment, and tilting every time the wafer is delivered to the wafer holder so that the contact surface of the wafer holder with the wafer becomes parallel to the wafer during the delivery. Tilt the substrate table (or tilt the wafer) using the measurement results
May be adjusted. Also in this case, improvement in throughput can be expected.

However, as a practical problem, the flatness of the wafer is likely to fluctuate at a minute level due to heat treatment or the like, and in consideration of this, it is desirable to perform the measurement every time.

In the first and second embodiments described above, the apparatus provided with the vertically moving center up 56 has been described, but the delivery method according to the present invention is not applied only to such an apparatus. For example, the transfer arm itself of the wafer loader may be vertically movable. In this case, in order to measure the inclination of the surface of the wafer W before the wafer is transferred to the wafer holder 34, a sensor 80 specialized for measuring the inclination of the wafer held by the transfer arm 48 as shown in FIG. Need to be provided separately from the leveling sensor 52, but even in this case, the method of the present invention can be applied. Further, the sensor 80 may be provided near the delivery position in addition to the leveling sensor even in the device having the center-up function. By doing so, it becomes possible to set the delivery position at a position away from the projection optical system PL.

Furthermore, in the first and second embodiments described above,
The center-up 56 serving as a wafer transfer member is provided at the center of the wafer holder 34 so as to be vertically movable (movable up and down), but the present invention is not limited to this. For example, as shown in FIGS. 9 (A) and 9 (B), a center-up consisting of three vertical movement pins 56A arranged at intervals of a central angle of 120 degrees on a circle concentric with the center of the wafer holder 34 It may be used as a member, or, as shown in FIGS. 10A and 10B, it is arranged symmetrically with respect to the center of the wafer holder 34 and can hold the wafer by contacting both sides of the back surface of the wafer. A wafer transfer member may be constituted by the two vertical movement members 56B. In any case, if the delivery member is provided with a contact portion such that the center of the wafer falls within the shape covered by the contact portion, it is possible to support the wafer mechanically and stably.

[0058]

As described above, according to the present invention, there is an unprecedented excellent effect that it is possible to surely suppress the occurrence of displacement of the substrate when the substrate is transferred to the substrate holder.

[Brief description of drawings]

FIG. 1 is a front view schematically showing an overall configuration of an exposure apparatus according to a first embodiment.

FIG. 2 is a plan view showing a state in which a portion above the upper plate of the first column is removed in the device of FIG.

FIG. 3 is a diagram showing a schematic configuration of a wafer vertical movement mechanism and a leveling sensor.

4 is a block diagram showing a configuration of a control system of the apparatus of FIG.

FIG. 5 is a flowchart showing a main control algorithm of the CPU in the main control device according to the first embodiment.

FIG. 6 is a diagram showing a multi-point focal position detection mechanism as a measuring unit according to a second embodiment together with a wafer vertical movement mechanism.

FIG. 7 is a flowchart showing a main control algorithm of the CPU in the main control device according to the second embodiment.

FIG. 8 is a diagram showing a modified example.

FIG. 9 is a diagram showing another configuration of center-up,
(A) is a plan view of the wafer holder portion, and (B) is a perspective view of the wafer holder portion.

10A and 10B are diagrams showing another configuration of the center-up, wherein FIG. 10A is a plan view of a wafer holder portion, and FIG. 10B is a perspective view of the wafer holder portion.

FIG. 11 is a diagram for explaining a conventional example.

[Explanation of symbols]

10 Exposure Device 28X X Stage (Stage) 32 Substrate Table 34 Wafer Holder (Substrate Holder) 48 Transfer Arm 48A Load Arm (Transfer Arm) 52 Leveling Sensor (Measurement Unit, Leveling Detection Mechanism) 56 Center Up (Part of Transfer Mechanism, Transfer) Part of the means 58 Center up drive mechanism (part of the transfer mechanism,
Part of transfer means 60 Main controller (control means, part of transfer means) 70 Multi-point focus position detection mechanism (measurement means) W Wafer (photosensitive substrate, substrate) R Reticle (mask) PL Projection optical system

Claims (8)

[Claims] 1. A substrate transfer method for transferring a substrate to a substrate holder provided on a stage, which measures a relative inclination between the substrate transported to a predetermined transfer position and the substrate holder. And a second step of transporting the substrate to the delivery position; and a contact surface of the substrate holder with the substrate that is in parallel with the substrate transported to the delivery position, based on the measurement result of the first step. To
A third step of adjusting the inclination of at least one of the substrate and the substrate holder conveyed to the transfer position; and thereafter, placing the substrate on the substrate holder while maintaining the inclination of the substrate and the substrate holder. And a fourth step of: delivering the substrate. 2. The first step is performed after the substrate is transported to the transfer position.
The method of delivering a substrate according to. 3. The substrate transfer method according to claim 1, wherein the first step is performed during assembly and adjustment of the substrate holder and a transfer mechanism for transferring the substrate to the substrate holder. 4. The substrate transfer method according to claim 3, wherein in the first step, the relative inclination is measured by a photoelectric collimator or a water bubble level. 5. An exposure apparatus for projecting and exposing a pattern formed on a mask onto a photosensitive substrate via a projection optical system, comprising a stage movable in a two-dimensional plane; mounted on the stage, A substrate table capable of adjusting the movement of the projection optical system in the optical axis direction and an inclination with respect to the optical axis; a substrate holder mounted on the substrate table and on which the photosensitive substrate is placed; a predetermined transfer position of the photosensitive substrate A transfer arm that transfers the photosensitive substrate between the transfer arm and the substrate holder; a measuring unit that measures an inclination of the photosensitive substrate; and a transfer unit that transfers the photosensitive substrate to the substrate holder. Every time it is delivered to the substrate holder, the inclination of the photosensitive substrate is measured using the measuring means during the delivery, and the substrate of the substrate holder is determined based on the measurement result. Exposure device contact surface and a control means for adjusting the tilt of the substrate table so as to be parallel with the photosensitive substrate. 6. Instead of the control means, the measuring means is used to measure the inclination of the photosensitive substrate only once in advance, and each time the photosensitive substrate is delivered to the substrate holder, the process is performed during the delivery. 6. A second control means for adjusting the inclination of the substrate table by using the result of the inclination measurement so that the contact surface of the substrate holder with the substrate is parallel to the photosensitive substrate. The exposure apparatus according to. 7. The exposure apparatus according to claim 5, wherein the measuring unit is a multipoint focus position detection mechanism that detects the positions of the photosensitive substrate surface at a plurality of positions in the optical axis direction. 8. The measuring means irradiates the surface of the photosensitive substrate with a parallel light beam from a direction oblique to the optical axis of the projection optical system, and detects the inclination of the photosensitive substrate based on the light receiving position of the reflected light beam. 7. The exposure apparatus according to claim 5, wherein the exposure apparatus is a leveling detection mechanism.