JP2000182936A - Exposure apparatus and manufacture of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress effect of vibration or the like of a projection optical members due to scan driving and of apparatus itself to stabilize accuracy of reference mark positions by setting the reference marks on a first stage means (mask stage), and making mask positioning based on the reference marks. SOLUTION: A main structural body St mounts a mask stage, which is a unit for placing a mask M in a projection exposure apparatus. A mask stage base 4 is movable on two guides 9 directed along Y-axis with a non-contact static air bearing system. The stage base 4 has an opening 16 in a passing through range of a projection exposure light, and a plurality of reference mark members Mb for the alignment of the mask M are provided at the inside wall of the opening 16. A plurality of reference marks are formed on the reference mark members Mb corresponding to a plurality of measurement marks Me on the mask M. Mutual positional misalignment is measured using a built-in CCD camera with an imaging lens for a magnified shot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus for exposing a photosensitive substrate such as a glass plate for a liquid crystal panel or a semiconductor manufacturing wafer.

[0002]

2. Description of the Related Art Normally, semiconductor elements and liquid crystal display elements are manufactured by a photolithography technique. In an exposure apparatus used at this time, a circuit pattern formed on an original (mask or reticle) is formed by a projection optical system. At a predetermined magnification on a photosensitive substrate (glass plate or wafer).

FIG. 2 is a diagram schematically showing the configuration of a conventional liquid crystal projection exposure apparatus. In FIG. 2, an exposure light source 1
After being converged by the elliptical mirror 2, the entire surface or a partial area of the mask M is irradiated with a uniform illuminance distribution through a well-known illumination optical system (not shown). AX is the optical axis. The mask M is held on the mounted mask chuck 3 by vacuum suction. The pattern on the mask M in the area irradiated with the illumination light is image-formed and projected on the plate P via the projection optical system PL. The plate chuck 5 fixes the placed plate P by vacuum suction, and
It has a stage mechanism (plate stage) that can move in the θ and Z directions. In FIG. 2, 4 is a mask stage base, 6 is an X stage, 7 is a Y stage, 8 is a plate stage base, the mask stage base 4 is included in the mask stage, and the X stage 6 and the Y stage 7 are included in the plate stage. It is.

Although not shown in FIG. 2, this plate stage has a structure in which the position of the XYθ axis is measured by a laser interferometer and controlled based on the measurement data to enable high-precision positioning and movement. ing. In this conventional example, it does not matter whether the mask stage and the plate stage scan. If the projection optical system is sufficiently large for the pattern area of the mask, batch exposure may be performed without scanning. If the optical system can obtain only a partial projection area, scan exposure is performed. However, the present invention is based on an exposure apparatus in which the plate size is several times larger than the mask size and step exposure is required.

In a projection exposure apparatus having such a configuration,
The positioning accuracy of the mask is an important performance factor of the exposure apparatus. If the mask position is shifted in the X and Y directions, the transfer position of the mask pattern on the plate will be shifted, and in the case of the second (second) layer and subsequent layers, there will be a problem that the transferred plate cannot be automatically aligned. I do. In addition, if the mask position is shifted in the θ direction, the arrangement accuracy of each exposure pattern at the time of step exposure is deteriorated.

Therefore, usually, a mark M used for positioning the mask at at least two positions of the mask M is provided.
e, and the reference mark Mb corresponding to this mark is provided.
Is provided in the main body structure Pt of the exposure apparatus or the lens barrel of the projection optical system PL, and the mask Me is aligned with the reference mark Mb so that the mask M is always arranged at a fixed position. It has become.

When the mask is aligned with respect to the mask reference mark Mb in this manner, since the positioning accuracy of the mask is required to be as high as 1 μm or less, the mask M and the mask reference mark Mb are very few μm. Generally, they are arranged at small intervals. It is conceivable to arrange the projection optical system between the mask and the mask reference mark to increase the distance between the mask and the mask reference mark.In this case, however, the image distortion and stability of the projection optical system are determined with high accuracy. It becomes a factor to hinder.

Therefore, it is desirable to reduce the gap as much as possible within a range where the mask does not contact the mask reference mark when the mask is driven.

[0009]

In recent years, in an exposure apparatus for a semiconductor or a liquid crystal, a mask and a plate are synchronized with each other for the purpose of securing an exposure area as large as possible by using a projection optical system having a limited size. Scanning exposure apparatuses that perform scanning and exposure have come into use. Even in such a scanning exposure apparatus,
Naturally, highly accurate positioning of the mask described above is indispensable. Therefore, it is necessary to adopt a method of positioning the mask with respect to the mask reference mark as in the related art.

However, as described above, since the interval between the mask and the mask reference mark is only a few μm, it is almost impossible to scan the mask in this state. Also, it is considered that the above configuration is practically impossible in terms of the device configuration.

In recent years, exposure apparatuses have been required to further improve alignment accuracy. On the other hand, as the exposure area has expanded, the entire apparatus has also become larger. Therefore, if a reference mark for alignment of a mask serving as a first reference is arranged on the structure as in the related art, the position of the reference mark is easily affected by vibration of the projection optical system and the apparatus main body due to scan driving. Is not stable. In addition, since the attitude of the structure constructing the apparatus and the observation optical system for alignment are changed in conjunction with the scanning drive of the stage, an error is included in the alignment measurement.

The present invention solves the above-mentioned problems in the conventional example. At least a conventional projection exposure apparatus that aligns an original by providing a reference mark on a main body structure of an exposure apparatus or a barrel of a projection optical system is provided. While maintaining the same accuracy,
It is an object of the present invention to provide means capable of inexpensively positioning an original.

[0013]

In order to solve the above-mentioned problems, the present invention provides a first stage means which sucks and holds an original on which an original pattern to be exposed is formed and is movable in XYθ directions, A projection optical system for projecting the original image pattern onto a predetermined image forming surface; and a X-ray in a plane parallel to the image forming surface while holding a photosensitive substrate substantially parallel to the image forming surface.
Second stage means movable in the Yθ direction, and the first and second stage means are synchronously scanned in a direction orthogonal to the optical axis of the projection optical system, so that the entire surface of the original image pattern is formed on a photosensitive substrate. In a projection exposure apparatus that performs exposure transfer at a predetermined position, a reference mark is arranged on the first stage means, and the mask is positioned with respect to the reference mark.

[0014]

According to the present invention, in a scan type projection exposure apparatus, it is not necessary to dispose a reference mark for positioning an original (mask) on a structure forming the apparatus, and instead, a first scan for scanning is performed. (Mask stage). In a scanning projection exposure apparatus, the position of the mask scan stage is controlled with high accuracy by monitoring the position of the mask stage with a laser interferometer. Therefore, even if the mask reference mark is provided on the mask scan stage,
It is possible to maintain the same accuracy as when a mask reference mark is provided on a main body structure as in the related art.

Further, by disposing the reference mark inside the stage to be scanned and driven, the scanning drive makes the projection optical system and the apparatus main body less susceptible to vibration and the like, so that the reference mark position accuracy is stabilized and the alignment measurement error is reduced. As a result, the alignment time is shortened, the throughput of the apparatus is improved, and the operation rate of the apparatus can be increased.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a mask stage portion of a slit scan exposure type projection exposure apparatus to which the present invention is applied. A light source, an illumination optical system, a projection optical system, a plate stage, and the like, not shown in FIG. In FIG. 1, a main body structure St mounts a mask stage (including a mask stage base 4) which is a unit for arranging a mask M in the projection exposure apparatus, and an observation optical system for aligning the mask M. It supports a system As and a projection optical system PL (not shown). Naturally, the projection optical system PL is disposed below the mask stage in the Z direction, and the structure St is provided with an opening 15 through which exposure light can pass.

The mask stage base 4 can move on the two guides 9 in the Y-axis direction in a non-contact manner by a static pressure bearing air system. A yaw guide 10 is mounted on one of the guides 9 and regulates yawing of the mask stage.

Two linear motors 12 are employed as actuators for scanning the mask stage in the Y direction, and can generate a high torque thrust. The stage base 4 and the linear motor 12 are fastened by the connecting plate 11, and transmit the thrust of the linear motor to the mask stage.

An opening 16 is provided in the stage base 4 in a range where the illumination exposure light is transmitted.
Reference mark member Mb for alignment of mask M on inner wall
Are arranged. A movable mirror By is fixed above and behind the stage base 4, and the coordinates of the mask stage unit are measured by a laser interferometer (not shown) mounted on the main body. Further, although not shown in FIG. 1, a plurality of actuators for driving in the X, Y, and θ directions are arranged on the stage base 4 as coordinate axes different from the coordinate axes of the unit, and hold the mask M by suction. It is possible to slightly drive the chuck 3. The mask M transported from the loader hand Mx is the observation optical system As
After being aligned within a predetermined range by an external shape pre-alignment mechanism (not shown) of the mask M provided on the chuck 3 so as to fall within the supplementary range, the mask M is vacuum-sucked by the suction groove on the chuck 3.

A plurality of reference marks are formed on the reference mark member Mb in correspondence with the plurality of measurement marks Me on the mask M, and are provided in the observation optical system As for enlarged photographing. The mask measurement magnification is optimized by an image lens (not shown), and the relative displacement is measured by a built-in CCD camera (not shown). Then, the shift amount is fed back to a stage position control system (not shown) to provide
The alignment is performed by slightly driving the chuck 3 in the XYθ directions by the above actuator. After the alignment of the mask M is completed, the chuck 3 is fixed to the stage base 4 using a lock pad Rp by a vacuum suction method. Thereafter, the apparatus aligns a plurality of alignment marks provided on the plate with the measurement marks Me in the aligned mask M using the plate stage, and synchronously drives the mask and the plate stage in that state. Perform exposure.

Although the method of the above embodiment mainly describes a mask alignment method for an apparatus for scanning and exposing a liquid crystal display element, the reticle alignment method for an apparatus for scanning and exposing a semiconductor element is also described above by applying this description. Similar effects can be expected. As described above, the present invention is not limited to the above-described embodiment, and can take various configurations without departing from the gist of the present invention.

[0022]

[Embodiment of Device Production Method] Next, an embodiment of a device production method using the above-described projection exposure apparatus will be described. FIG. 3 shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micro machines, etc.). In step 1 (circuit design), a device pattern is designed. Step 2
In (mask production), a mask on which a designed pattern is formed is produced. On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. Next Step 5
The (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes an assembly process (dicing, bonding).
It includes steps such as a packaging step (chip encapsulation). In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 4 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern on the mask is printed and exposed on the wafer by the scan exposure type projection exposure apparatus having the above-described mask alignment apparatus. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the production method of this embodiment, it is possible to produce a highly integrated device, which was conventionally difficult to produce, at low cost.

[0025]

As described above, according to the present invention, an original pattern of an original (mask or reticle) used in a manufacturing process of a liquid crystal display element or a semiconductor element is slit-scanned on a photosensitive substrate (plate or wafer). This is effective for use in an alignment method of an original in a projection exposure apparatus that performs exposure with a mask. In recent years, exposure apparatuses have been required to further improve alignment accuracy. On the other hand, as the exposure area has expanded, the entire apparatus has also become larger. Therefore, if the reference mark for alignment of the original plate serving as the first reference is arranged on the structure as in the related art, the reference mark is easily affected by vibration of the projection optical system and the apparatus main body due to scan driving, and the like. Position is not stable. In addition, since the attitude of the structure constructing the apparatus by the scan drive of the stage and the observation optical system for alignment cooperate with each other, an error occurs during alignment measurement. However, according to the present invention, since the reference mark is arranged inside the stage to be driven for scanning, the reference mark is hardly affected by the vibration in the apparatus as described above, and the reference mark position accuracy is stabilized, and the alignment measurement error is reduced. As a result, the alignment time is shortened, the throughput of the apparatus is improved, and the operation rate of the apparatus can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a mask alignment method in a slit scan method according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the overall configuration of a conventionally used projection exposure apparatus.

FIG. 3 is a diagram showing a flow of manufacturing a micro device.

FIG. 4 is a diagram showing a detailed flow of a wafer process in FIG. 3;

[Explanation of symbols]

M: mask, PL: projection optical system, P: plate, As:
Observation optical system, Ax: optical axis, By: movable mirror, Mb: reference mark, Me: measurement mark, Mx: loader hand, R
p: lock pad, St: structure, 1: light source for exposure,
2: Elliptical mirror, 3: Mask chuck, 4: Mask stage base, 5: Plate chuck, 6: X stage, 7:
Y stage, 8: plate stage base, 9: guide, 10: yaw guide, 11: connecting plate, 12: linear motor, 15: opening hole provided in structure, 16: opening hole provided in mask stage base.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Fukunaga 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5F046 BA05 CB17 CC02 CC03 CC06 CC09 CC15 DB05 EB02 EC01 ED03

Claims (2)

[Claims] 1. A first plate which holds an original plate on which an original image pattern to be exposed is formed by suction and is movable in XYθ directions.
A stage means, a projection optical system for projecting the original image pattern onto a predetermined image plane, and a photosensitive substrate held substantially parallel to the image plane and XYθ in a plane parallel to the image plane.
Second stage means movable in a direction, and the first and second stage means are synchronously scanned in a direction orthogonal to the optical axis of the projection optical system, so that the entire surface of the original image pattern is formed on a photosensitive substrate. An exposure apparatus for exposing and transferring to a predetermined position, wherein a reference mark is disposed on the first stage means, and the mask is positioned with respect to the reference mark. 2. A device manufacturing method, comprising manufacturing a device using the exposure apparatus according to claim 1.