JPH1062809A - Projection exposure method - Google Patents

Abstract

(57) Abstract: The present invention relates to a projection exposure method using a scanning projection exposure apparatus having a plurality of projection optical systems when manufacturing an active matrix type liquid crystal display device having a switching element. It is another object of the present invention to provide a projection exposure method capable of reducing screen divisions that degrade the image quality of a liquid crystal display device. When exposing a layer that affects screen division,
The drawing position of the reticle pattern and the transfer position of the substrate
The reticle and the substrate are synchronously scanned and shifted by a predetermined amount in a direction perpendicular to the optical axis of the projection optical system and perpendicular to the scanning direction. The position of the joint is shifted by a predetermined amount between the layers to be laminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure method using a scanning projection exposure apparatus having a plurality of projection optical systems, and more particularly to a method for manufacturing an active matrix type liquid crystal display device having switching elements. The present invention relates to a projection exposure method using a scanning projection exposure apparatus having a plurality of projection optical systems.

[0002]

2. Description of the Related Art In recent years, large-screen, high-definition color liquid crystal display devices (hereinafter referred to as LCDs) have been used for display devices of personal computers and television receivers. The size of the current LCD screen (diagonal width of the screen) is about 10 to 12 inches, but large-screen LCDs exceeding 16 inches, and more than 20 inches, have also been developed. The resolution of the screen corresponding to the enlargement of the screen is changed from the VGA (640 × 480) pixel number to the XGA (1024 × 768) and SXGA (12
LCDs corresponding to 80 × 1024 pixels are also being produced. These LCDs are active matrix type LCDs that are excellent in image display response, wide viewing angle characteristics, or multi-gradation, and in particular, each TFT has a thin film transistor (hereinafter referred to as a TFT) as a switching element. LCDs are becoming mainstream.

An outline of a configuration example of a display pixel of a TFT / LCD will be briefly described with reference to FIG. Figure 5 shows TFT / LC
FIG. 4 is an enlarged plan view of a partial region of a D array substrate (a substrate on which a TFT is formed). A plurality of gate lines 32 are formed on the glass substrate 42 in the horizontal direction of the display screen, and a plurality of data lines 30 are formed in the vertical direction. Each display pixel area surrounded by the gate line 32 and the data line 30 has I
A transparent pixel electrode 34 made of TO (indium tin oxide) is formed. A gate electrode 36 extending from the gate line 32 is formed at a corner of each display pixel region. On the gate electrode 36, for example, amorphous silicon (α-
A channel layer 44 made of Si) is formed. A drain electrode 40 extending from the data line 30 and a source electrode 38 formed simultaneously with the drain electrode 40 and electrically connected to the transparent pixel electrode 34 are formed on the channel layer 44. These gate electrode 36, gate insulating film, channel layer 44, source / drain electrode 3
The TFTs 8 and 40 constitute a TFT. The illustration and description of the storage capacitance line and the like are omitted.

A circuit pattern of each layer constituting the TFT / LCD is formed by a photolithography process. A circuit pattern formed on a photomask or a reticle (hereinafter referred to as a reticle) is exposed on a resist layer (photosensitive layer) applied on a glass substrate 42 using a projection exposure apparatus,
The semiconductor layer made of, for example, α-Si is etched to form the channel layer 44 by using the resist layer to which the circuit pattern has been transferred and developed as a mask, or the gate line 32 and the gate electrode 36 by etching the metal wiring layer, or For example, the data line 30 and the source / drain electrodes 38 and 40 are formed.

[0005] A scanning projection exposure apparatus having a plurality of projection optical systems is used because the projection exposure area of the projection exposure apparatus must be enlarged in response to the enlargement of the glass substrate 42 accompanying the enlargement of the screen of the TFT / LCD. It has come to be. This scanning projection exposure apparatus divides a circuit pattern of a reticle into a plurality of trapezoidal regions by a plurality of projection optical systems and projects the reticle onto a glass substrate, and simultaneously synchronizes the reticle and the glass substrate with the projection optical system. By scanning, the entire surface of the circuit pattern area on the reticle is transferred onto the glass substrate.

FIG. 6A shows a part of a projection area on a glass substrate 42 by a scanning projection exposure apparatus. The trapezoidal projection areas 50 and 52 of each projection optical system are arranged to overlap each other by a predetermined amount in order to uniformly irradiate the circuit pattern. The X direction in the figure is a direction in which the glass substrate 42 moves relatively to the projection regions 50 and 52. Also,
A region where the projection region 50 and the projection region 52 overlap in the Y direction is defined as a region b (eg, an overlap width of 5 mm), a non-overlapping region on the projection region 50 side is defined as a region a, and a non-overlapping region on the projection region 52 side is defined as a region c. .

In general, since the imaging characteristics of a plurality of projection optical systems mounted on a scanning projection exposure apparatus are different from each other, the imaging characteristics of the projection optical system that forms an image in the projection area 50 are shown in FIG.
As shown by the arrow, a shift of the image formation position is caused by the magnitude of ΔP in the −Y direction. Similarly, the imaging characteristic of the projection optical system that forms an image on the projection area 52 is + Y as shown by the arrow.
It is assumed that a deviation of the image formation position is caused by the magnitude of ΔP in the direction. FIG. 6 shows the positional deviation of the pattern of the layer formed by exposure using the projection optical system having such imaging characteristics.
This will be described with reference to FIG. The horizontal axis of FIG. 6B represents the position in the Y direction, and the vertical axis represents the error of the pattern formation position of the formed layer with respect to the design value. The position error of the pattern in the region a and the region c becomes ΔP, reflecting the imaging characteristics of the projection optical system. Since the directions in which the error occurs are opposite between the region a and the region c, the difference in the positional shift between the region a and the region c is 2ΔP. The area b includes the projection areas 50 and 5
In the region b, the ratio of the amount of exposure light changes linearly, and in the region b, the deviation of the position of the formed pattern changes linearly from -ΔP to + ΔP. In addition,
The area of the layer where the two projection areas are exposed in an overlapping manner will be referred to as a "joint".

As described above, if the plurality of projection optical systems of the scanning projection exposure apparatus have different image forming characteristics, the magnitude and direction of the positional deviation of the formed pattern are different across the joint. It will be. In the photolithography process, generally, a plurality of scanning projection exposure apparatuses are used, and each layer constituting a TFT is exposed using a different scanning projection exposure apparatus. Therefore, the overlay accuracy between the stacked layers depends not only on the difference in the imaging characteristics of the plurality of projection optical systems in the exposure apparatus described above, but also on the difference in the imaging characteristics of the projection optical systems between the scanning projection exposure apparatuses. Will be affected.

[0009] In view of the above, a description will be given of an overlay error generated between layers when a gate line and a gate electrode of a TFT and a data line and a source / drain electrode are formed using a plurality of scanning projection exposure apparatuses, with reference to FIG. . FIG. 7A is the same as FIG. 6A when forming the upper layer data lines and source / drain electrodes (hereinafter collectively referred to as source / drain electrodes) using the first scanning projection exposure apparatus. 3 shows the vicinity of the overlapping portion of the projection areas 50 and 52 on the glass substrate 42 of FIG. FIG. 7B shows the overlapping of the projection areas 54 and 56 on the glass substrate 42 when the lower gate line and the gate electrode (hereinafter collectively referred to as gate electrodes) are formed using the second scanning projection exposure apparatus. The vicinity of a part is shown. Projection area 5
The projection optical system that forms an image on the projection area 56 has a deviation of the image formation position by ΔP in the + Y direction as shown by an arrow. It is assumed that the imaging characteristic of (1) causes a shift in the imaging position with a magnitude of ΔP in the −Y direction as shown by the arrow.

As shown in FIGS. 7A and 7B, the upper layer is exposed by a projection optical system having an image forming characteristic which causes a shift of an image forming position opposite to that of the projection optical system for exposing the lower layer. , The case where the overlay error appears most remarkably.

FIG. 7C shows a case where a lower gate electrode is formed on a glass substrate by a second scanning projection exposure apparatus, and an upper source / drain electrode is formed by a first scanning projection exposure apparatus. Shows the superposition error of. The horizontal axis in FIG. 7C indicates the position in the Y direction, and the vertical axis indicates the error.
A broken line A in the figure indicates a position shift of the formed gate electrode,
The thin solid line B indicates the displacement of the formed source / drain electrodes. A thick solid line C indicates an overlay error (C = BA) between the gate electrode and the source / drain electrode. Since the overlay error is the difference between the displacement of the upper source / drain electrode with respect to the lower gate electrode, the overlay error between the gate electrode and the source / drain electrode formed in the region a is −2ΔP. On the other hand, the overlay error between the gate electrode and the source / drain electrode formed in the region c in the same manner is 2ΔP. A region b where the joint of the two layers of the gate electrode layer and the source / drain electrode layer overlaps
As described with reference to FIG. 6, the superposition error in the pattern changes linearly from −2ΔP to 2ΔP because the pattern displacement of both the gate electrode and the source / drain electrode changes linearly. Therefore, the amount of change in the overlay error in the region b is 4ΔP in the width of the region b.

FIG. 8 shows a concrete example of this. FIG. 8 shows a TF formed by the above-described projection exposure method.
This shows how the gate electrode 36 and the source / drain electrodes 38 and 40 overlap in each TFT region of the T / LCD. FIG. 8A shows an overlay error between the gate electrode 36 and the source / drain electrodes 38 and 40 in the region a in FIG. The shape shown by the broken line in the drawing is the design pattern formation position of each layer. On the other hand, the gate electrode 36 is formed so as to be uniformly shifted in the + Y direction, and the source / drain electrodes 38 and 40 are formed so as to be uniformly shifted in the −Y direction. Similarly, in FIG. 8C, the gate electrode 36 and the source / drain electrode 3 in the region c in FIG.
8 and 40 show overlay errors. Gate electrode 3
6, the source / drain electrodes 38 and 40 are formed so as to be uniformly shifted in the + Y direction. In the region b where the two joints between the region a and the region c overlap, as shown in FIG. 8B, the overlay error of the two layers decreases near the center of the region b, and both ends of the region b As approaching the portion, the overlapping error of the region a or the region c is approached, respectively.

[0013]

As described above, in the ordinary exposure process in the manufacture of an LCD, since exposure is performed using a different scanning projection exposure device for each layer forming process, each projection optical system of the exposure device is exposed. If the difference between the image forming characteristics and the difference between the image forming characteristics of the projection optical system between the exposure apparatuses becomes large, the overlay accuracy is greatly affected.

Particularly in the manufacture of a TFT, for example, when the amount of superposition of the gate electrode and the source electrode changes, the parasitic capacitance between the gate and the source changes, so that the element characteristics of the TFT change. The change in the element characteristics of this TFT is
It appears as flickering and burning on the LCD screen.

As is apparent from FIG. 7, if the amount of change in the overlay error at the joint formed by the region b where the projection regions overlap is large, the element characteristics of the TFT greatly differ on both sides of the joint. In addition, the difference between left and right image quality is visually recognized with the joint as a boundary, and the image quality is degraded. This phenomenon is generally called “screen division” or “division unevenness”.

An object of the present invention is to provide a projection exposure method capable of reducing screen divisions that degrade image quality of a liquid crystal display device.

[0017]

SUMMARY OF THE INVENTION The object of the present invention is to provide a projection display apparatus in which each projection area is separated on the substrate surface, and adjacent portions of each projection area are arranged within the substrate plane in a direction perpendicular to the scanning direction of the substrate. Projecting a part of the first pattern onto the substrate in the first plurality of projection regions overlapping by the overlap width, and synchronizing the first pattern and the substrate with respect to the first plurality of projection regions; The first pattern is transferred onto the substrate by scanning in the scanning direction,
Projecting a part of the second pattern onto the substrate in a second plurality of projection regions in which the plurality of projection regions are shifted by a predetermined shift width in a direction perpendicular to the scanning direction in the substrate plane; The projection exposure method is characterized in that the second pattern and the substrate are synchronously scanned in the scanning direction with respect to the two plurality of projection areas, and the second pattern is transferred onto the substrate.

In order to relatively displace the second plurality of projection areas with respect to the first plurality of projection areas, the arrangement of the reticle on which the first pattern is drawn and the substrate are as follows.
The arrangement of the reticle on which the second pattern is drawn and the substrate may be shifted relative to each other in the direction perpendicular to the scanning direction within the substrate plane by the predetermined shift width. Alternatively, the writing position of the second pattern on the reticle is shifted relative to the writing position of the first pattern on the reticle by a predetermined shift width in a direction perpendicular to the scanning direction on the substrate surface, The position of the substrate with respect to the second pattern may be shifted relative to the position of the substrate with respect to the first pattern by a predetermined shift width in a direction perpendicular to the scanning direction in the plane of the substrate.

Further, a second plurality of projection optical systems for projecting onto a second plurality of projection regions are provided on the substrate surface with respect to a first plurality of projection optical systems for projecting onto the first plurality of projection regions. It may be relatively shifted by a predetermined shift width in a direction perpendicular to the scanning direction.

Further, the above object is achieved by making the predetermined shift width substantially equal to the predetermined overlap width in the projection exposure method. Alternatively, it is also achieved by setting the predetermined shift width within a range from the predetermined overlap width to approximately twice the predetermined overlap width.

In the present invention, when exposing a layer that affects screen division, the drawing position of the reticle pattern and the transfer position of the substrate are set in a direction perpendicular to the optical axis of the projection optical system and perpendicular to the scanning direction. By shifting the reticle and the substrate by a predetermined amount and performing scanning exposure in synchronization with each other, the position of the joint portion of the layer formed by divisional exposure by the plurality of projection optical systems is shifted by a predetermined amount between the layers to be laminated. Therefore, the change of the overlay error at each joint can be made equal to the position error of the joint.

Further, if the predetermined shift amount is made larger than the width of the joint, the upper and lower joints will not affect each other. Accordingly, since the maximum value of the overlay error can be reduced to half of the conventional value, even if the joint portion is doubled by shifting the joint portion, the screen division is not visually recognized.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection exposure method according to a first embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of a projection exposure apparatus used in the projection exposure method according to the present embodiment will be described with reference to FIG. FIG. 1 has a plurality of projection optical systems, is an erect erect image as a whole, and has an enlargement magnification of 1.
FIG. 1 is a perspective view of a double scanning projection exposure apparatus 1. In FIG.
The direction (scanning direction) in which the reticle 2 on which the predetermined circuit pattern is provided and the glass substrate 4 coated with the resist are conveyed is the X axis, the direction orthogonal to the X axis in the plane of the reticle 2 is the Y axis, The coordinate system uses the normal direction of the reticle 2 as the Z axis. In FIG. 1, an illumination optical system 3 for uniformly illuminating a reticle 2 in an XY plane in the figure is provided with a trapezoidal field stop (not shown) so that light images of adjacent patterns overlap by a predetermined amount. Have been. Illumination optical system 3
After luminous flux emitted from a light source (not shown) is made uniform through an optical system including a fly-eye lens and the like, each projection exposure area is shaped into a trapezoid by a field stop, and the circuit pattern on the reticle 2 is illuminated. It is supposed to.

The reticle 2 is mounted on a reticle stage (not shown).
It can be moved in the Y direction. Below the reticle 2, a plurality of projection optical systems 5a to 5g are arranged at positions corresponding to the respective apertures of the field stop. Projection optical system 5a-
5g is configured by combining two sets of Dyson optical systems. The projection optical systems 5a to 5g include a projection optical system 5a, 5b, 5c and a projection optical system 5d when viewed from the Z direction.
5e, 5f, and 5g are arranged in two rows in a staggered manner.

When the reticle 2 is irradiated with the trapezoidal illumination lights 6a to 6g by such a configuration, the pattern on the reticle 2 is changed to the glass substrate 4 via the projection optical systems 5a to 5g.
An image is formed on the upper trapezoidal projection areas 7a to 7g. The glass substrate 4 is mounted on an XY stage (not shown), and can move in the X and Y directions with the movement of the stage.

By moving the reticle stage and the XY stage in the X direction in synchronization with the projection optical system, the pattern on the reticle 2 is transferred with a uniform exposure distribution over all directions on the glass substrate 4. be able to. As described above, the scanning projection exposure apparatus 1 has a plurality of projection optical systems 5a to 5a.
Since the configuration is such that 5 g is combined, a large exposure area can be obtained without increasing the exposure area of each projection optical system.

FIG. 2 is a plan view showing projection areas 7a to 7g of exposure light projected onto the glass substrate 4 by the projection optical systems 5a to 5g. Each of the projection areas 7a to 7g is formed into a trapezoidal image and has a predetermined shape so that the sum of the widths of the projection areas 7a to 7g along the scanning direction (X direction) is always constant at any position in the Y direction. The trapezoidal upper bases are opposed to each other so as to form an image in a staggered manner so as to overlap with an overlapping width (for example, 5 mm). Therefore, by performing the scanning exposure, the total exposure amount of the overlapping projection regions of the projection regions 7a to 7g on the glass substrate 4 can be the same as that of the non-overlapping regions. , A uniform exposure amount distribution is obtained. In the present embodiment, the shapes of the projection regions 7a to 7g are trapezoidal. However, the combination of the shapes of the projection regions for obtaining a uniform exposure amount distribution is as follows.
The shape is not limited to the trapezoidal shape, and may be, for example, a hexagonal shape. Using a plurality of such scanning projection exposure apparatuses 1, exposure is performed by separate scanning projection exposure apparatuses 1 for each layer of the TFT.

The projection exposure method according to the present embodiment will be described with reference to FIG. In this embodiment, a process for forming a gate electrode layer and a source / drain electrode layer will be described as an example. In the following description, the scanning projection exposure apparatus used for exposing the gate electrode layer and the components thereof are denoted by the reference numerals in FIG. 1, and another scanning projection exposure apparatus used for exposing the source / drain electrodes and The components are distinguished from each other by using the components in FIG. The projection regions 7a to 7g described with reference to FIG. 2 will be similarly distinguished.

First, a reticle 2 on which a gate electrode forming pattern for forming a lower gate electrode is drawn is placed on a reticle stage (not shown) of the scanning projection exposure apparatus 1 using the scanning projection exposure apparatus 1. . The pattern image is
The light is divided by the projection optical systems 5a to 5g and projected onto a resist layer (not shown) applied on the glass substrate 4 in the projection areas 7a to 7g shown in FIG.

By moving the reticle 2 and the glass substrate 4 synchronously with respect to the plurality of projection optical systems 5a to 5g, the entire gate electrode forming pattern is exposed on the resist layer on the glass substrate 4.

FIG. 3B shows an overlapping portion of the projection area 7a and the projection area 7e on the glass substrate 4 in the exposure using the scanning projection exposure apparatus 1. As shown in FIG. 3B, a projection optical system 5a that forms a pattern on the projection area 7a
Of the projection optical system 5e that forms a pattern in the projection area 7e in the + Y direction as shown by the arrow. Indicates that the imaging position shifts by a magnitude of ΔP in the −Y direction as shown by the arrow.

Using the resist layer developed after exposure as a mask for forming a gate electrode, the lower metal wiring layer is patterned to form a gate electrode layer.

Subsequently, after forming a gate insulating film, a channel layer, etc., the scanning projection exposure apparatus 1 used for forming the gate electrode is used.
Exposure for forming source / drain electrodes is performed by using another scanning projection exposure apparatus 1 '. First, using a scanning projection exposure apparatus 1 ', a reticle 2' on which a source / drain electrode forming pattern for forming an upper layer source / drain electrode is drawn is placed on a reticle stage (not shown) of the scanning projection exposure apparatus 1 '. Place.

At this time, the reticle 2 'is supplied to the plurality of openings of the field stop (not shown) of the illumination optical system 3' and the plurality of projection optical systems 5a 'to 5g' provided corresponding to the openings. The source / drain electrode forming pattern and the glass substrate 4 are shifted by a predetermined amount in a direction perpendicular to the optical axis of the projection optical systems 5a ′ to 5g ′ and the moving direction of the reticle 2 ′ and the glass substrate 4 (ie, the Y direction). Try to shift by an amount. If the drawing position of the source / drain electrode forming pattern on the reticle 2 'and the drawing position of the gate electrode forming pattern on the reticle 2 are substantially the same, the scanning projection exposure apparatus 1' on which the reticle 2 'is mounted. To move the reticle 2 ′ to a position shifted by a predetermined shift amount in the Y direction from the mounting position of the reticle 2 on the reticle stage of the scanning projection exposure apparatus 1 used for forming the gate electrode. Just do it. Along with this operation, the XY stage on which the glass substrate 4 is placed is also shifted by a predetermined shift amount in the Y direction.

The pattern image of the reticle 2 'is divided by the projection optical systems 5a' to 5g 'to form projection areas 7a' to 7g.
g ′ is projected onto a resist layer (not shown) applied on the glass substrate 4.

FIG. 3A shows the vicinity of the overlapping portion of the projection area 7a 'and the projection area 7e' on the glass substrate 4 in the exposure using the scanning projection exposure apparatus 1 '. FIG.
As shown in (a), the imaging characteristic of the projection optical system 5a 'that forms a pattern on the projection area 7a' is -as shown by the arrow.
It is assumed that the image forming position is shifted by ΔP in the Y direction, and similarly, the image forming characteristic of the projection optical system 5e ′ for forming a pattern in the projection area 7e ′ is in the + Y direction as shown by the arrow. It is assumed that the displacement of the imaging position is caused by the magnitude of ΔP.

Since the reticle 2 'and the glass substrate 4 are shifted by a predetermined amount with respect to the projection optical systems 5a' to 5g ', the projection area 7 for forming the source / drain electrodes shown in FIG.
The overlap region b 'of a' and 7e 'is shifted in the Y direction by a predetermined shift amount with respect to the overlap region b of the projection regions 7a and 7e for forming a gate electrode. In the present embodiment, the predetermined shift amount is set to the width of the overlapping area b 'of the projection areas 7a' and 7e '.

Next, the reticle 2 'and the glass substrate 4 are moved in the X direction in synchronization with the plurality of projection optical systems 5a' to 5g 'so that the entire pattern for forming source / drain electrodes is The upper resist layer is exposed. Using the resist layer developed after exposure as a mask for forming source / drain electrodes, the underlying metal wiring layer is patterned to form source / drain electrode layers.

The overlay error in the thus formed gate electrode and source / drain electrode is shown in FIG.
This will be described with reference to FIG. In FIG. 3C, the horizontal axis represents the position in the Y direction, and the vertical axis represents the error. In the figure, the broken line A indicates the positional deviation of the formed gate electrode, and the thin solid line B indicates the positional deviation of the formed source / drain electrode. A thick solid line C indicates an overlay error (C = BA) between the gate electrode and the source / drain electrode.
Since the overlay error is the difference between the displacement of the upper source / drain electrode with respect to the lower gate electrode, the overlay error between the gate electrode and the source / drain electrode formed in the region a is −2ΔP. On the other hand, the overlay error between the gate electrode and the source / drain electrode formed in the region c is 2ΔP.

Further, since the formed joint (region b) of the gate electrode layer and the joint (region b ') of the source / drain electrode layer are adjacent to each other but do not overlap, the overlay error in the region b Corresponds to-
It changes linearly from 2ΔP to 0. Similarly, the overlay error in the region b ′ linearly changes from 0 to 2ΔP in accordance with the displacement of the source / drain electrodes. Therefore, the change amount of the overlay error in the region b + b ′ is 4ΔP
Becomes In other words, according to the projection exposure method in the present embodiment, the joint between the lower gate electrode layer and the source /
Since the spliced portion of the drain electrode layer and the spliced portion are shifted by the width of the spliced portion, the change of the overlay error at each spliced portion can be made equal to the change of the positional error of the spliced portion. The amount of change 4ΔP of the overlay error is the same as the conventional one, but since the width of the region where the overlay error changes has doubled, the rate of change in the element characteristics of the TFT at the joint (thick solid line C in the figure) Can be halved as compared with the prior art. Therefore, a plurality of TFTs whose element characteristics change gently so as to interpolate between them are formed between two types of TFTs having different element characteristics, and this is caused by a difference in the imaging characteristics of each projection optical system. Screen division can be reduced.

Next, a projection exposure method according to a second embodiment of the present invention will be described with reference to FIG. The scanning projection exposure apparatus used in the projection exposure method according to the present embodiment is the same as that described in the first embodiment, and a description thereof will be omitted. The image forming characteristics of each projection optical system of each projection exposure apparatus are the same as those described with reference to FIG. FIGS. 4A and 4B show the positional relationship between the projection regions 7a 'and 7e' for forming source / drain regions on the glass substrate 4 and the projection regions 7a and 7e for forming gate electrodes. ing. In the present embodiment, the amount of shift between the positions of the projection regions 7a and 7e in the Y direction when forming the gate electrodes and the projection regions 7a 'and 7e' when forming the source / drain electrodes is determined in the first embodiment. The width of the region b 'and the region b "is set to be substantially equal to the width of the joint portion b.

FIG. 4C shows a graph in which a scanning type exposure apparatus 1 forms a lower gate electrode on a glass substrate 4 using the projection exposure method according to the present embodiment. 'Indicates an overlay error when an upper layer source / drain electrode is formed. In the figure, the horizontal axis represents the position in the Y direction, and the vertical axis represents the error. In the figure, the broken line A indicates the positional deviation of the formed gate electrode, and the thin solid line B indicates the positional deviation of the formed source / drain electrode. A thick solid line C indicates an overlay error (C = BA) between the gate electrode and the source / drain electrode.
Since the overlay error is the difference between the displacement of the upper source / drain electrode with respect to the lower gate electrode, the overlay error between the gate electrode and the source / drain electrode formed in the region a is −2ΔP. On the other hand, the overlay error between the gate electrode and the source / drain electrode formed in the region c is 2ΔP.

Further, since the formed joint portion (region b) of the gate electrode layer does not overlap with the joint portion (region b ″) of the source / drain electrode layer, the overlay error in the region b is reduced by the gate error. The position changes linearly from −2ΔP to 0 in accordance with the displacement of the electrodes, and the overlay error in the region b ′ between the lower seam (region b) and the upper seam (region b ″) is Since the projection optical systems of the overlapping projection areas 7e and 7a 'have the same imaging characteristics, and the gate electrode and the source / drain electrode are formed with the same positional error, the overlay error becomes zero.

The overlay error in the region b 'is calculated by
It changes linearly from 0 to 2ΔP corresponding to the displacement of the drain electrode. As described above, according to the projection exposure method in the present embodiment, the joint between the lower gate electrode layer and the joint between the upper source / drain electrode layers is shifted by twice the width of the joint between the stacked layers. As a result, the change in the overlay error at each joint can be made equal to the change in the position error of the joint, and by making the predetermined shift amount larger than the width of the joint, the upper and lower layers can be changed. So that the joints do not affect each other,
The change amount of the overlay error can be reduced from 4ΔP to 2ΔP. Further, since the region where the overlay error changes is made into two stages, the rate of change of the TFT element characteristics at the joint (the slope of the thick solid line C in the figure) can be made more gentle than in the first embodiment. it can. Therefore, a plurality of TFs whose element characteristics change gradually so as to interpolate between two types of TFTs having different element characteristics.
Since T is formed, it is possible to reduce screen division caused by a difference in the imaging characteristics of each projection optical system.

Since the maximum value of the overlay error can be reduced to half of the conventional one, even if the joint portion is doubled by shifting the joint portion, the screen division is not visually recognized.

As described above, by shifting the pattern and the glass substrate relatively twice in the Y direction relative to the projection optical system of the scanning projection exposure apparatus, the gate electrode and the source / drain The screen division due to the change in the element characteristics of the TFT at the joint portion due to the electrode overlay error can be made less noticeable. Screen division is a phenomenon in which a difference in left and right image quality is confirmed by human vision due to a sharp change in overlay accuracy at a joint boundary. According to the projection exposure method in the present embodiment, since the overlay error at the joint boundary changes more slowly than in the conventional method, it is possible to sufficiently suppress the screen division.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above two embodiments,
The case where the predetermined shift amount is almost equal to the width of the joint portion (the width of the region b) and almost doubled is described.
The present invention is, of course, not limited to this. For example, even if the shift amount is equal to or less than the width of the joint, the overlay error at the joint boundary can be changed, so that appropriate suppression of screen division is realized. be able to.

For example, in the above embodiment,
In particular, the case where the gate electrode layer and the source / drain electrode layer are exposed as layers that affect the screen division has been described. The present invention can be used.

Further, in the above-described embodiment, in order to shift the joint of the formed layers by a predetermined shift amount, the mounting position of the reticle 2 ′ for forming the upper layer on the reticle stage is changed to the lower layer. Reticle 2 for forming
Although the method of shifting by a predetermined shift amount relatively in the Y direction from the mounting position is used, the present invention is not limited to this, and the point is that the joint between the lower layer and the upper layer is relatively shifted. Just do it. Accordingly, for example, a reticle in which the drawing position of the pattern for forming source / drain electrodes on the reticle and the drawing position of the pattern for forming the gate electrode on the reticle are relatively shifted by a predetermined amount in the Y direction. It may be formed and exposed using the reticle. Further, the opening of the field stop of the scanning projection exposure apparatus 1 'and the mounting position of the projection optical systems 5a' to 5g 'are changed to the opening of the field stop and the projection optical system 5 of the scanning projection exposure apparatus 1.
It may be shifted from the mounting positions a to 5g by a predetermined shift amount in the Y direction.

Further, as a method for shifting the reticle pattern and the glass substrate with respect to the projection optical system by a predetermined amount in the Y direction for scanning and exposing the joint, one of the layers affecting the screen division is moved in the + Y direction. And the other layer may be exposed to be shifted in the −Y direction, and may be exposed to be shifted by a predetermined amount, and various modes are possible.

[0051]

As described above, according to the present invention, the overlay error can be sufficiently suppressed, and the screen division which deteriorates the image quality of the TFT / LCD can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a scanning projection exposure apparatus used in a projection exposure method according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a projection area projected on a glass substrate.

FIG. 3 is an explanatory diagram of a projection exposure method according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a projection exposure method according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a TFT / LCD.

FIG. 6 is a diagram illustrating a conventional projection exposure method.

FIG. 7 is a diagram illustrating a conventional projection exposure method.

FIG. 8 is a diagram illustrating a conventional projection exposure method.

[Explanation of symbols]

 Reference Signs List 1 scanning projection exposure apparatus 2 reticle 3 illumination optical system 4 glass substrate 5a to 5g projection optical system 6a to 6g illumination light 7a to 7g projection area 30 data line 32 gate line 34 transparent pixel electrode 36 gate electrode 38 source electrode 40 drain electrode 42 glass substrate 44 channel layer 50, 52, 54, 56 projection area

Claims (6)

[Claims] 1. A projection area is separated from each other on a substrate surface, and adjacent portions of the projection areas overlap with each other in the substrate plane by a predetermined overlap width in a direction perpendicular to a scanning direction of the substrate. First
Projecting a part of the first pattern onto the substrate in the plurality of projection areas, and performing the first projection on the first plurality of projection areas.
Scanning the pattern in synchronization with the substrate in the scanning direction to transfer the first pattern onto the substrate, and the first plurality of projection areas are perpendicular to the scanning direction in the substrate plane. A part of a second pattern is projected onto the substrate in a second plurality of projection areas relatively shifted by a predetermined shift width in a predetermined direction, and the second plurality of projection areas are projected onto the second plurality of projection areas. A second pattern is transferred onto the substrate by scanning the pattern in synchronization with the substrate in the scanning direction. 2. The projection exposure method according to claim 1, wherein the arrangement of the reticle and the substrate on which the second pattern is drawn is different from the arrangement of the reticle and the substrate on which the first pattern is drawn. The second plurality of projection areas are relatively shifted with respect to the first plurality of projection areas by being shifted by the predetermined shift width relatively in a direction perpendicular to the scanning direction in the substrate plane. And a projection exposure method. 3. The projection exposure method according to claim 1, wherein a drawing position of the second pattern on the reticle is set in the substrate plane with respect to a drawing position of the first pattern on the reticle. Shifted by a predetermined shift width in a direction perpendicular to the scanning direction, with respect to the position of the substrate with respect to the first pattern,
By displacing the position of the substrate with respect to the second pattern within the substrate plane in a direction perpendicular to the scanning direction by the predetermined displacement width, the position of the substrate with respect to the first plurality of projection areas is reduced. A projection exposure method, wherein the two projection areas are relatively shifted. 4. The projection exposure method according to claim 1, wherein said first plurality of projection optical systems projecting onto said first plurality of projection areas are projected onto said second plurality of projection areas. The second plurality of projection optical systems are shifted relative to the first plurality of projection regions by shifting the plurality of projection optical systems relative to each other in the direction perpendicular to the scanning direction within the substrate plane. A projection exposure method characterized by relatively shifting an area. 5. The projection exposure method according to claim 1, wherein said predetermined shift width is substantially equal to said predetermined overlap width. 6. The projection exposure method according to claim 1, wherein the predetermined shift width is within a range from the predetermined overlap width to approximately twice the predetermined overlap width. Characteristic projection exposure method.