JPH1187234A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aligner, which can perform the adjustment of the beam shape from a laser light source with the state of the atmospheric space of a lighting system tightly enclosed in the specified atmosphere which is maintained in the exposing system used in a photolithographic process. SOLUTION: A beam-shape adjusting control system 80 obtains the beam shape of the illuminating light emitted from a laser light source 12 from a beam-shape detector 48 and discriminates whether an aspect ratio or a beam size is located in the region of the specified beam shape or not. When it is discriminated that the value is not located in the specified range, the beam shape is adjusted by driving the driving systems 56-60 of three kinds of cylinder zoom-lens units 50-54. The beam shape in the adjustment is fed back from the beam shape detector 48. When the shape is adjusted to the range of the specified beam shape, the adjusting operation is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure apparatus used in a photolithography process in manufacturing a semiconductor device, a liquid crystal display device, or the like.

[0002]

2. Description of the Related Art In a photolithography process in a manufacturing process of a semiconductor device or a liquid crystal display device, a circuit pattern formed on a reticle or a mask (hereinafter, referred to as a mask) is formed through a projection optical system onto a semiconductor wafer or a glass plate (hereinafter, referred to as a mask). A projection exposure apparatus that performs projection exposure on a wafer is used. There are various types of projection exposure apparatuses. For example, in the case of manufacturing a semiconductor device, the wafer is stepped through a projection optical system having an image field capable of including the entire circuit pattern of the mask.
There are a projection exposure apparatus that performs exposure by an AND repeat method, and a projection exposure apparatus that employs a so-called step-and-scan method in which a mask is one-dimensionally scanned while a wafer is one-dimensionally scanned at a speed synchronized therewith.

In recent years, these projection exposure apparatuses have been required to have higher exposure accuracy than before, and in order to achieve a desired exposure accuracy, the illumination light emitted from the laser light source must be accurately irradiated with a predetermined beam shape. It is also necessary to make it shaped. For example, when the illumination light emitted from the laser light source enters the fly-eye lens of the illumination optical system, if the illumination light has a beam size wider than the incident area to the fly-eye lens, there is no waste of light used for exposure. If light is generated and the beam size is narrower than the optimum incident area to the fly-eye lens, a situation may occur in which the amount of light required for exposure is insufficient. Therefore, it is necessary to adjust the beam shape of the illumination light emitted from the laser light source as optimally as possible with respect to the fly-eye lens. In particular, the beam size or the aspect ratio (aspect ratio) generated when the laser light source is exchanged is reduced. Similarly, it is desired that the correction and adjustment can be easily performed with respect to a change in the beam shape that occurs when the laser light source is repaired, or a change in the beam aspect ratio due to the aging of the laser light source. I have.

[0004]

For this reason, the conventional exposure apparatus is provided with a cylinder zoom lens unit and the like as a mechanism for changing and adjusting the beam shape of the illumination light emitted from the laser light source. It is arranged in the N ₂ -substituted closed space, and when trying to correct and adjust the beam shape of the illumination light from the laser light source, if the N ₂ -substituted closed space is not broken once, the cylinder zoom lens unit, etc. Could not adjust the beam shape. Therefore,
At present, after adjusting the beam shape of the illumination light from the laser light source at the time of shipment of the exposure apparatus, the beam shape is not corrected or adjusted unless the laser light source is repaired or replaced. Even if the beam shape of the illumination light is adjusted at the time of repair or replacement of the laser light source, N ₂
The work for creating a sealed space for replacement is complicated and takes a long time, which causes a decrease in throughput. Furthermore, in such a situation, there is also a problem that it is not possible to monitor a change in the beam shape that occurs based on a temporal change of the laser light source and make any adjustment.

An object of the present invention is to provide an exposure apparatus which can adjust the shape of a beam from a laser light source while maintaining the state of an atmosphere space of an illumination system sealed in a predetermined atmosphere.

[0006]

An object of the present invention is to illuminate a mask with laser light from a laser light source through an illumination optical system sealed in a predetermined atmosphere, and apply an image of a pattern formed on the mask to a substrate. In an exposure apparatus that performs exposure, a beam shape detector that detects a beam shape of laser light in an illumination optical system, a beam shape adjustment system that adjusts a beam shape, and controls detection of a beam shape by the beam shape detector. And a control system for controlling a beam shape adjusting system so that the beam shape detected by the beam shape detector becomes a predetermined beam shape. In this exposure apparatus, the control system may start the control operation based on a request signal from the laser light source.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An exposure apparatus according to an embodiment of the present invention will be described with reference to FIGS. The present embodiment is an example in which the present invention is applied to a step-and-repeat projection exposure apparatus. First, a schematic configuration of the projection exposure apparatus according to the present embodiment will be described with reference to FIG. Illumination light from, for example, a KrF excimer laser (wavelength 248 nm) 12 passes through a beam shape adjusting mechanism in an N ₂ -substituted hermetic space unit 14 described in detail later with reference to FIG. Is converted into a substantially parallel light beam.

The illumination light collimated by the collimator lens 3 enters a fly-eye lens 22 functioning as an optical integrator. This fly eye lens 2
A number of secondary light source images are formed on the emission side 2, and illumination light from each secondary light source image enters the condenser lens 26.
The illumination light passing through the condenser lens 26 is transmitted to the lens system 3
The mask M is radiated via the mirror 0, the mirror 32 and the main condenser lens.

The mask M is mounted on a mask stage (not shown) which can move two-dimensionally in the XY plane in the figure, and is controlled by a mask stage laser interferometer (not shown) to control the position of the mask stage. You can move with it.

The illumination light transmitted through the mask M enters the projection optical system PL and is condensed, and forms an image of the pattern of the mask M in an image field of the projection optical system PL. In the present embodiment, the projection optical system PL is configured by a refracting element reduced by 両 側 or １ ／ by telecentric on both sides, or a combination of a refracting element and a reflecting element.

Below the projection optical system PL, a wafer stage W on which a wafer W is placed and which can move two-dimensionally in the XY plane
ST is provided. Wafer stage WST is moved in the X direction by drive system 6, and is moved in the Y direction by a drive system (not shown) in the Y direction. The movement amount of the wafer stage WST is sequentially measured by the wafer stage laser interferometer 7 in the X-axis direction (the laser interferometer in the Y-axis direction is not shown).

Further, the wafer W is sucked on a wafer holder (not shown), and the surface of the wafer W can be made to coincide with the field surface of the image field by the projection optical system PL by moving the wafer holder in the Z direction. I have.

The control unit 8 receives position information of the wafer stage WST and a mask stage (not shown) from position detecting means such as the laser interferometer 7. The control device 8 gives a command to the drive system 6 and the like based on the position information, and controls the wafer stage WST or a mask stage (not shown) to move to a predetermined position. Further, the controller 8 sends a command to the beam shape adjustment control system 80 based on, for example, a request signal input from the laser light source 12 to the beam shape adjustment control system 80, and the beam shape adjustment mechanism in the hermetic space unit 14 The beam shape is adjusted.

The beam shape adjusting mechanism in the hermetic space unit 14 will be described with reference to FIG. The illumination light from the laser light source 12 is reflected by the mirror 40 and enters the cylinder zoom lens unit 50. In the present embodiment, the cylinder zooming lens unit 50 is driven by the drive system 56, and the aspect ratio (aspect ratio) of illumination light having a rectangular beam shape emitted from the laser light source 12 is rectangular.
Is changed by adjusting the vertical length of the beam. The illumination light transmitted through the cylinder zoom lens unit 50 is bent by the mirror 42 and enters the cylinder zoom lens unit 52. The cylinder zooming lens unit 52 is driven by a drive system 58 and is used to expand and contract the beam shape of the illumination light in the horizontal direction to change the aspect ratio. Furthermore, the illumination light transmitted through the cylinder zoom lens unit 52 is bent by the mirror 44 and enters the cylinder zoom lens unit 54. The cylinder zooming lens unit 54 is driven by the drive system 60 and is used to adjust the size of the illumination light by enlarging or reducing the beam shape without changing the aspect ratio.

The driving systems 56 to 60 of the cylinder zooming lens units 50 to 54 are controlled and driven by a beam shape adjustment control system 80. The illumination light emitted from the cylinder zooming lens unit 54 is partially transmitted by the half mirror 46 and enters the beam shape detector 48, and the rest is reflected and enters the main illumination system after the collimator lens 3.

The beam shape detector 48 is, for example, a two-dimensional C
It is composed of an image pickup device such as a CD, and is capable of two-dimensionally measuring the beam shape of the incident illumination light. The output of the beam shape from the beam shape detector 48 is
The data is input to the beam shape adjustment control system 80.

Next, the operation of adjusting the beam shape in the beam shape adjusting mechanism having such a configuration will be described. The beam shape adjustment in the beam shape adjustment mechanism according to the present embodiment can be performed only when the laser light source 12 is repaired or replaced, for example, while the N ₂ -substituted hermetic space is maintained and the beam shape can be adjusted. In addition, the present invention is characterized in that a beam shape change due to a temporal change of a laser light source is periodically grasped, and the beam shape can be corrected and adjusted appropriately.

Now, a request signal for starting the adjustment operation to the beam shape adjustment control system 80 is transmitted to the laser light source 12.
Or beam shape adjustment control system 8
The adjustment operation of the beam shape is started by either sending an adjustment operation command from the control device 8 to 0. When these signals are input, the beam shape adjustment control system 80
The beam shape of the illumination light emitted from the laser light source 12 is acquired from the beam shape detector 48. Then, the beam shape adjustment control system 80 determines whether or not the acquired beam shape has an aspect ratio or a beam size within the range of the predetermined beam shape. If it is determined that the difference is not within the predetermined range, the beam shape is adjusted by driving one or more of the three types of cylinder zoom lens units 50 to 54 by driving their drive systems 56 to 60. At this time, the beam shape being adjusted is fed back from the beam shape detector 48 to the beam shape adjustment control system 80 at predetermined time intervals. When the beam shape acquired from the beam shape detector 48 is adjusted within a predetermined beam shape range, the beam shape adjustment control system 8
0 sends an adjustment end signal to the laser light source 12 or the control device 8 to end the adjustment operation.

More specifically, when the beam size and aspect ratio of the illumination light are changed, for example, by exchanging the laser light source 12, the cylinder shape lens unit is monitored while the beam shape is monitored by the beam shape detector 48. Zooming is performed by 50 to 54, and fine adjustment control is performed based on the beam size and aspect ratio of the illumination light preset in the laser light source so as to obtain a desired optimum beam size and aspect ratio. Similarly, when the beam shape is changed due to repair of the laser light source,
While actually monitoring the beam shape by the beam shape detector 48, the symbol adjustment control is performed by the cylinder zooming lens units 50 to 54 so as to obtain the optimum beam size and aspect ratio.

Further, the controller 8 periodically instructs the beam shape adjustment control system 80 to acquire beam shape data, and outputs beam shape data from the beam shape detector 48 so that the time of the laser light source can be reduced. The change in the beam aspect ratio due to the change can be monitored and adjusted, and the illumination light can be constantly maintained in the optimum beam shape.

In this embodiment, as a zooming optical system for changing the beam shape, a cylinder zoom lens unit 54 which is a cylinder zoom having an optical system for simultaneously changing the aspect ratio, and an optical system for separately changing the aspect ratio A cylinder zoom lens unit 50 having
52, but also a cylinder zoom lens unit having an optical system with a large zooming change ratio (for coarse adjustment) and a cylinder zoom lens unit with an optical system with a small zooming ratio (for fine adjustment) , And can be used in an optimal combination according to the specifications and design conditions of the apparatus. Further, in order to cope with a case where the beam size and the aspect ratio of the illumination light are extremely different from desired amounts, two or a plurality of zooming optical systems may be prepared and switched to be used.

Next, the structure of the cylinder zoom lens unit according to the present embodiment will be briefly described. FIG. 3 shows a state in which the drive systems 56 and 58 are assembled to the cylinder zoom lens units 50 and 52, respectively. FIG.
1 shows an example in which a lens unit performing zooming is driven by a drive system including a motor and a feed screw. In FIG. 3, a lens barrel 90 including a cylindrical lens is inserted in a cylindrical housing 92 so as to be movable in the optical axis direction of the lens. A bearing (not shown) is provided around the lens barrel portion 90, and the lens barrel portion 90 is connected to the feed screw unit 9 of the drive systems 56 and 58 fixed to the outside of the housing 92 via the bearing.
6 is connected. A cutout groove 100 is provided on the side surface of the housing 92 in the optical axis direction, and the bearing can move in the optical axis direction following the cutout groove 100. Therefore, by rotating the motor 94 connected to the feed screw unit 96, the bearing is notched by the notch groove 100.
Thus, the lens barrel 90 can be moved in the optical axis direction. Note that the cylindrical lenses in the lens barrel portions 90 of the cylinder zoom lens units 50 and 52 are arranged to be orthogonal to each other in a plane perpendicular to the optical axis.

Cylinder zoom lens units 50 and 52
And other examples of the driving systems 56 and 58 will be described with reference to FIG.
FIG. 4 shows a drive system 5 for performing cylinder zoom zooming.
6 and 58 are different from FIG. 3 in that they are air slide units using pneumatic pressure. 4, the lens units 50 and 52 are the same as those in FIG. The lens barrel 90 is connected to the air slide unit 102 of the drive systems 56 and 58 fixed to the outside of the housing 92 via a bearing (not shown) provided around the lens barrel 90. With the movement of the air slide unit 102, the bearings
Accordingly, the lens barrel 90 can be moved in the optical axis direction, and the lens barrel 90 can be moved in the optical axis direction.

FIG. 5 shows a drive unit for performing laser beam zooming by simultaneously changing the lens distance between two lens barrels. The zoom lens unit 54 is driven by a combination of a motor and a gear. An example of driving by a drive system 60 is shown.

Bearings 12 are provided at both ends of each of the lens barrels 104 and 106 each including a cylindrical lens.
0 and 122 are attached two by two. These bearings 120 and 122 operate according to the cutout grooves formed in the circular cylinder 110 and the circular cylinder 112 connected via the bearing 108. Notch grooves parallel to the optical axis direction are formed on both side surfaces of the round tube 110, and cutout grooves having an arbitrary inclination or a solution curve are formed on both side surfaces of the round tube 112, respectively. Therefore, by rotating the round tube 112 about the optical axis, the lens barrel units 104 and 106 can be moved in the optical axis direction without being rotated. Each of the lens barrels 104 and 106 can zoom the illumination light from the laser light source by changing the distance between the lenses according to the two solution curves processed into the round cylinder 112. A gear 114 is attached to the outer periphery of the round tube 112, and a motor 118 through a gear unit 116 is provided.
Thus, rotation can be given to the round tube 112 to perform zooming.

As described above, according to the present embodiment, N ₂
While maintaining the replaced sealed space, the beam shape of the illumination light from the laser light source is constantly or when necessary monitored and the cylinder zoom lens unit is driven to adjust the beam shape as desired. Will be able to do it.

[0027]

As described above, according to the present invention, the beam shape of the illuminating light from the laser light source can always be kept in an optimum state, so that a more accurate exposure state can be maintained. In addition, since the N ₂ -substituted airtight space is not broken, a waiting time for performing the N ₂ -substitution again becomes unnecessary, so that the throughput can be improved. Further, the work for N ₂ substitution can be reduced, and the worker is not directly exposed to the laser beam, which is effective from the viewpoint of safety.

[Brief description of the drawings]

FIG. 1 is a view showing a schematic structure of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic structure of a beam shape adjusting mechanism according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a schematic structure of an example of a cylinder zoom lens unit.

FIG. 4 is a diagram illustrating a schematic structure of another example of the cylinder zoom lens unit.

FIG. 5 is a diagram illustrating a schematic structure of still another example of the cylinder zoom lens unit.

[Explanation of symbols]

 Reference Signs List 8 control device 12 laser light source 14 airtight space unit 48 beam shape detector 50-54 cylinder zooming lens unit 56-60 drive system 80 beam shape adjustment control system

Claims (2)

[Claims] 1. An exposure apparatus for irradiating a mask with laser light from a laser light source via an illumination optical system sealed in a predetermined atmosphere and exposing a substrate to an image of a pattern formed on the mask, A beam shape detector for detecting a beam shape of the laser light in the illumination optical system; a beam shape adjusting system for adjusting the beam shape; and controlling the beam shape detection by the beam shape detector and the beam shape. An exposure apparatus, comprising: a control system that controls the beam shape adjustment system so that a beam shape detected by the detector becomes a predetermined beam shape. 2. An exposure apparatus according to claim 1, wherein said control system starts a control operation based on a request signal from said laser light source.