JP3517560B2 - Projection exposure apparatus and device manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type in which an original such as a mask and a photosensitive substrate are synchronously scanned in predetermined directions to sequentially expose a pattern on the original onto a photosensitive substrate. The present invention is suitable for an exposure apparatus, particularly when applied to a step-and-scan projection-type scanning exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor device, a liquid crystal display device, a thin film magnetic head or the like is manufactured by a photolithography process, a pattern of a photomask or a reticle (hereinafter referred to as a reticle) is a photosensitive substrate. A projection exposure apparatus that transfers images onto a wafer or a glass plate (hereinafter referred to as a wafer) has been proposed.

The main projection exposure apparatus is a step-and-repeat type reduction projection exposure apparatus (hereinafter referred to as a stepper) that sequentially transfers and exposes an image of a reticle pattern onto a wafer.

5 and 6 show a part of the structure of a conventional stepper. The reticle stages 51, 52, 53, 54 are structured to hold the reticle 1 and move in the X, Y, and θ directions. On the reticle stage base 54,
Y stage 53 movable in Y direction, X stage 52 movable in X direction, θ stage 51 movable in θ direction
Is configured. A reference mark 59 for aligning the reticle is mounted on the reticle stage base 54. Reticle alignment microscopes 5 and 6 (hereinafter, referred to as RAS) are configured above the reticle stage. Below the reticle stage, the projection optical system 1
0, wafer stages 11 to 15 are configured.

FIG. 6 is a view for explaining the reference mark 59 portion in detail. A reference mark 59 for aligning the reticle is mounted on the reticle stage base 54. The reference mark 59 is the light source 56 that is configured externally.
Is illuminated via the fiber 57 and the illumination optical system 58. Illuminated fiducial mark 59 and reticle 1
The upper mark image is taken into the RAS 5, 6 by the mirrors 5a, 6a.

The reticle 1 is sent onto the θ stage 51 by a reticle transfer device (not shown) and is adsorbed. Then, the RAS 5 and 6 observe the mark on the reticle 1 and the reference mark 59 to detect the relative position. Based on the detection result,
The reticle stages 51, 52, 53 are driven, and the reticle 1 is aligned with the reference mark 59.

In recent years, a scanning type exposure apparatus has been proposed. In an example of the scanning type exposure apparatus disclosed in Japanese Patent Laid-Open No. 7-176468, when a reticle is aligned with the apparatus, an illumination unit included in the substrate stage illuminates a reference mark included in the substrate stage, so that the reticle is exposed. The alignment microscope detects the relative position of the reticle and the reference mark, and aligns the reticle.

[0008]

In recent years, patterns have become finer in semiconductor devices and the like. In order to realize this, it is necessary to increase the resolution of the projection optical system. In order to increase the resolution, there are methods such as shortening the wavelength of exposure light or increasing the numerical aperture of the projection optical system.

On the other hand, looking at the chip pattern of one semiconductor element, it tends to increase in size. Therefore, there is a need for an apparatus capable of exposing a pattern having a larger area.

In order to satisfy the above two items, a projection optical system having a large exposure area and high resolution is required.
However, the larger the exposure area and the higher the resolution, the more difficult it becomes to maintain the imaging performance such as distortion in the entire exposure area at a predetermined accuracy. Therefore, the scanning exposure apparatus is currently receiving attention. In the scanning type exposure apparatus, a rectangular shape or
The pattern of the reticle is transferred onto the wafer while scanning the reticle and the wafer relatively synchronously with respect to the slit-shaped illumination area such as the arc shape.

In this method, the reticle is illuminated in a slit shape so that only a part of the projection optical system is used. Therefore, there is an advantage that the imaging performance such as distortion can be easily maintained at a predetermined accuracy.

Further, by illuminating the reticle in a slit shape, the maximum diameter of the effective exposure area of the projection optical system can be used, and by scanning, the exposure area is not restricted in the scanning direction by the optical system. It has the advantage that it can be expanded.

In the above scanning exposure apparatus, the pattern of the reticle is transferred onto the wafer while scanning the reticle and the wafer relatively synchronously. For this reason, control for synchronously scanning is important. In particular, when the projection optical system is used under a projection magnification of 1/5 or 1/4, the reticle is 5 or 4 with respect to the wafer.
Must scan at double speed. Further, in contrast to the conventional stepper that performs the batch exposure, the scanning exposure apparatus has the disadvantage of throughput because the exposure is performed while scanning.

Therefore, it is important how to scan the reticle at high speed and to achieve high synchronization control accuracy.
To achieve this, it is important to reduce the weight of the movable part of the reticle stage, but as shown in the above conventional example, the reticle alignment drive unit, reference mark, reference mark illumination unit, etc. are mounted on the reticle stage. However, there is a problem that the weight cannot be reduced. The same applies in the wafer stage but also the reticle stage, weight reduction is an important issue.

When a fiber is used to guide the illumination light, the fiber must be bent as the reticle stage is driven. For this reason, there is a problem that disconnection or the like is likely to occur. The location where the disconnection occurs is inside the reticle stage, and it is difficult to configure the location where replacement is easy, and the occurrence of the disconnection is a serious problem for the apparatus. This applies not only to the reticle stage but also to the wafer stage.

In view of the above problems of the prior art, the object of the present invention is to reduce the weight of the original stage and the substrate stage in a step-and-scan type projection exposure apparatus, and to use an optical fiber for introducing illumination light. It is to try to solve the problem caused by the disconnection.

[0017]

To achieve this object, in a projection exposure apparatus according to a first aspect of the present invention, an illumination optical system for illuminating an original plate with illumination light from a light source, and a pattern of the original plate on a substrate. A projection optical system for projecting upward, an original stage that holds the original plate for scanning the original plate and moves in a first direction, and a first stage that holds the substrate for scanning the substrate. A substrate stage which moves in a second direction corresponding to the direction, a reference mark which is provided on the original plate stage and serves as a reference for positioning the original plate, and a positioning mark on the original plate for positioning the original plate Step-and-scan projection exposure including a mark and a microscope for observing the reference mark, and mark illuminating means for illuminating the positioning mark and the reference mark for the observation In location, the mark illuminating means
It is provided to some or all the parts that do not move by pre Symbol original stage, the position from below the original stage
Illuminating the placement mark and the reference mark at the same time
The microscope is positioned above the original plate.
It is characterized in that the working mark and the reference mark are observed at the same time .

[0018]

Further, the device manufacturing method of the present invention is characterized in that such a projection exposure apparatus is used, the original plate is positioned by using the mark illuminating means and the microscope, and the original plate pattern is exposed on the substrate. To do.

As a result, the weight of the original stage or the substrate stage can be reduced. Further, when the optical fiber is used for guiding the illumination light in the mark illuminating means, the problem due to the disconnection of the optical fiber can be solved.

[0021]

In a preferred embodiment of a projection exposure apparatus according to a first aspect of the embodiment of the present invention, the front Symbol original stage includes a scanning stage which moves for the first direction of scanning, the A fine movement stage which is provided above and finely moves to hold the original plate for positioning the original plate, and the reference mark is fixed on the scanning stage.

[0022]

In a preferred embodiment of the device manufacturing method of the present invention, the projection exposure apparatus of such an embodiment is used.

[0024]

1 shows a projection exposure apparatus according to the first embodiment of the present invention. An outline of the scanning exposure is shown in FIG.
At this time, the pattern on the reticle 1 is illuminated by exposure light from an illumination optical system (not shown), and the projection optical system 1
Projection exposure is performed on the wafer 11 via 0. The reticle 1 scans the illumination area of the exposure light in the depth direction with respect to the paper surface at a constant speed RV. At this time, the wafer 11 is scanned at a constant speed RV / M in the front direction in synchronization with the scanning speed RV of the reticle with respect to the paper surface of FIG. Here, M represents the reduction magnification of the projection optical system 10. When the reticle 1 is scanned in the front direction with respect to the paper surface, the wafer is scanned in the back direction with respect to the paper surface.

Explaining the structure of the reticle stage section, a reticle stage base 4 is mounted with a Y stage 3 which can be driven in the Y-axis direction perpendicular to the plane of the drawing. The reticle fine movement stage 2 is mounted on the Y stage 3, and the reticle 1 is held on the reticle fine movement stage 2 by a vacuum chuck or the like on the reticle fine movement stage 2. The reticle fine movement stage 2 can be driven by a small amount in the X, Y, and θ directions within a plane perpendicular to the optical axis of the projection optical system 10.

A mirror 2a is provided on the reticle fine movement stage 2.
And the position of the reticle fine movement stage 2 is monitored by an interferometer 4a arranged on the reticle stage base 4. The position information monitored by the interferometer 4a is supplied to the control system 7.

Explaining the structure of the wafer stage unit, a wafer Y stage 14 is mounted on a wafer stage base 15 and is freely drivable in the Y-axis direction. Wafer Y
A wafer X stage 13 that can be driven in the X-axis direction orthogonal to the Y-axis is mounted on the stage 14. On the wafer X stage 13, a Z that can be driven in the Z direction and the θ direction
The θ stage 12 is mounted, and the wafer 11 is held on the Zθ stage 12 by vacuum suction. A mirror 12a is arranged on the Zθ stage 12, and the position of the Zθ stage 12 is monitored by an interferometer 9 arranged outside. The position information monitored by the interferometer 9 is the control system 7
Is supplied to. The control system 7 uses the wafer stage drive system 8 to control the wafer Y stage 14, the wafer X stage 13, and the Z stage.
The drive of the θ stage 12 is controlled and the operation of the entire apparatus is controlled.

Above the reticle 1, reticle alignment microscopes (hereinafter referred to as RAS) 5 and 6 are formed. The mark image on the reticle illuminated by a light source formed below the reticle 1 described below is reflected by the mirrors 5a and 6a.
It is taken into RAS5,6 by a. The captured mark image is processed by the image processing unit 5 formed in the RAS 5, 6.
b, 6b and is supplied to the control unit 7 as position information.

The light source formed below the reticle 1 will be described with reference to FIG. A reference mark base 21 is fixed on the Y stage 3 with bolts 22. A reference mark plate 20 on which a reference mark 20a for aligning the reticle is drawn is fixed on the reference mark base 21 by adhesion or the like. A mark la is drawn on the reticle 1 at a position corresponding to the reference mark 20a. The reticle stage base 4 includes a light source 25 for illuminating the reference mark 20a and the mark la, an illumination optical system 24, and a mirror 23.
The light source 25, the illumination optical system 24, and the mirror 23 are arranged at positions that do not interfere with each other even when the Y stage 3 is driven.

To explain the operation, the Y stage 3 moves to a position where the reticle 1 is supplied. The reticle 1 is transferred onto the reticle fine movement stage 2 by a reticle transfer device (not shown) and is fixed by suction. In order to align the reticle, the light source 25 is turned on and the illumination optical system 2
4. The reference mark 20a and the mark la are illuminated via the mirror 23. The images of the reference mark 20a and the mark la are taken into the RAS 5 and 6 by the mirrors 5a and 6a. The captured image is the image processing unit 5 in the RAS 5, 6.
b and 6b, the reticle 1 and the reference mark 20 are processed.
The relative position of a is detected. The detected information is the control system 7
The control system 7 drives the reticle fine movement stage 2 to align the reticle 1 with the reference mark 20a.

The reticle fine movement stage 2 of this embodiment corresponds to the conventional reticle stages 51 to 54 of FIG.
If the conventional example is applied as it is, it is necessary to configure a light source and an illumination optical system in the reticle fine movement stage section. Further, the light guiding fiber must also be held in a bendable state as the Y stage 3 is driven. On the other hand, according to the present embodiment, since the parts other than the reference mark 20a are not driven, it is not necessary to form them on the Y stage 3.
It is possible to reduce the weight of the Y stage drive unit.

( Reference Example ) FIGS. 3 and 4 show reference examples . The same elements as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

This reference example differs from the first embodiment in that
In the first embodiment, the illumination unit for reticle alignment is provided in the lower portion of the reticle, whereas in this reference example , the reference mark is provided on the wafer side and the illumination unit is also provided on the wafer side. That is the point.

The structure is shown in FIG. The difference from FIG. 1 is that Z
This is the point that the reticle alignment reference mark 30 is formed on the θ stage 12.

FIG. 4 shows details of the illumination portion of the reference mark 30. Below the reference mark 30, an illumination unit for the reference mark 30 is configured. The illumination light is a light source 4 that is configured outside.
From 0, the fiber 41, the illumination optical systems 42, 43, 45,
It is guided to the lower surface of the reference mark 30 via the beam splitter 44 and the mirror 46, and illuminates the reference mark 30 from the rear surface. The reference mark image is taken into the RAS 5, 6 by the mirrors 5a, 6a via the projection optical system 10 and the reticle 1.

The reference mark images taken into the RAS 5 and 6 are imaged on the camera 49 via the optical systems 47a and 47b and the mirror 48. The signal of the mark image formed on the camera 49 is processed by the image processing unit 50 and supplied to the control system 7.

In the conventional example disclosed in Japanese Patent Laid-Open No. 7-176468, the reference mark illumination optical system is formed on the stage. On the other hand, in this reference example , a part of the illumination optical system is configured outside the stage or in a part that is not driven. This is because the position for aligning the reticle is always a constant position, and the illumination light only has to illuminate the reference mark and the reticle only at the alignment position. As a result, a part of the illumination optical system can be arranged separately from the drive unit, and the weight of the stage can be reduced.

According to the projection exposure apparatus of the first embodiment of the present invention, it is possible to dispose the reticle alignment reference mark illumination section separately from the reticle stage movable section. This makes it possible to reduce the weight of the movable portion of the reticle stage. Therefore, it is possible to scan the reticle at high speed and achieve high synchronization control accuracy.

Further, when the fiber is used to guide the illumination light, conventionally, the fiber had to be bent along with the driving of the reticle stage. For this reason, there is a problem that disconnection etc. is easy to occur,
According to the projection exposure apparatus of the first embodiment of the present invention, since the fiber can be mounted on the fixed portion, the risk of disconnection can be avoided.

Further, the illumination light for reticle alignment is
Since it is not used via the projection optical system, a light source having a wavelength different from that of the exposure light can be used. This makes it possible to reduce the running cost when a light source such as an excimer laser, which causes a running cost, is used as the exposure light.

Similarly, when a short wavelength light such as an excimer laser is used as the exposure light, the material of the glass material that can be used as the optical system is limited to expensive materials such as quartz. According to the embodiment, the cost of the apparatus can be reduced by using the light source having the wavelength different from that of the exposure light as the illumination light. Also, as shown in the reference example ,
Also on the wafer stage side, the same effects as above, weight reduction,
Fiber break prevention can be realized.

Next, a device manufacturing example that can utilize the above-described exposure apparatus will be described. Figure 7 shows microdevices (semiconductor chips such as IC and LSI, liquid crystal panels, CC
D, thin film magnetic head, micromachine, etc.). In step 31 (circuit design), the circuit of the semiconductor device is designed. In step 32 (mask manufacturing), a mask having the designed circuit pattern is manufactured.
On the other hand, in step 33 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 34 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the mask and the wafer prepared above. The next step 35 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer manufactured in step 34, such as an assembly process (dicing, bonding), a packaging process (chip encapsulation) and the like. including. In step 36 (inspection), the semiconductor device manufactured in step 35 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes and shipped (step 37).

FIG. 8 shows a detailed flow of the wafer process. In step 41 (oxidation), the surface of the wafer is oxidized. In step 42 (CVD), an insulating film is formed on the wafer surface. In step 43 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 44 (ion implantation), ions are implanted in the wafer. Step 45
In (resist processing), a photosensitive agent is applied to the wafer. In step 46 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the above-described exposure apparatus. In step 47 (development), the exposed wafer is developed. In step 48 (etching), parts other than the developed resist image are removed. In step 49 (resist stripping), the unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, a highly integrated semiconductor device, which has been difficult to manufacture in the past, can be manufactured at low cost.

[0045]

According to the present invention as described in the foregoing, it is possible to achieve weight reduction of the original stage. When an optical fiber is used to guide the illumination light in the mark illuminating means, it is possible to prevent the optical fiber from being broken and solve the problem due to the disconnection.

[Brief description of drawings]

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

2 is a partial detailed view of the apparatus of FIG.

FIG. 3 is a schematic diagram showing a projection exposure apparatus according to a reference example of the present invention.

FIG. 4 is a partial detailed view of the apparatus of FIG.

FIG. 5 is a schematic view of a stepper according to a conventional example.

6 is a partial detailed view of the apparatus of FIG.

FIG. 7 is a flowchart showing a flow of manufacturing a micro device which can be manufactured by the apparatus of FIG. 1 or FIG.

8 is a flowchart showing a detailed flow of the wafer process in FIG.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-5-343293 (JP, A) JP-A-6-291019 (JP, A) JP-A-7-176468 (JP, A) JP-A-7- 321022 (JP, A) JP 8-78314 (JP, A) JP 8-241845 (JP, A) JP 8-293453 (JP, A) JP 9-36024 (JP, A) JP-A-9-153451 (JP, A) JP-A-9-162114 (JP, A) JP-A-63-133625 (JP, A) JP-A-64-10105 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 7/20

Claims (3)

(57) [Claims] 1. An illumination optical system for illuminating an original plate with illumination light from a light source, a projection optical system for projecting a pattern of the original plate on a substrate, and a first holding unit for holding the original plate for scanning the original plate. Provided on the original stage; and an original stage that moves in the direction of, a substrate stage that holds the substrate for scanning the substrate and moves in a second direction corresponding to the first direction, A reference mark serving as a reference for positioning the original plate, a positioning mark on the original plate for positioning the original plate, and a microscope for observing the reference mark, and the positioning mark and the reference for the observation. In a step-and-scan projection exposure apparatus provided with a mark illuminating means for illuminating a mark, the mark illuminating means moves a part or all of the mark by the original stage. It is provided in a non-existing portion, and illuminates the positioning mark and the reference mark from the lower side of the original plate at the same time, and the microscope simultaneously observes the positioning mark and the reference mark from the upper side of the original plate. And a projection exposure apparatus. 2. The original stage is a scanning stage that moves for scanning in the first direction, and a fine movement stage that is provided on the scanning stage and holds the original plate and finely moves to position the original plate. 2. The projection exposure apparatus according to claim 1, further comprising: and the reference mark is fixed on the scanning stage. 3. Using the projection exposure apparatus according to any one of claims 1 to or 2, performs positioning of the original by using the mark illuminating means and microscopic, characterized by exposing a pattern of an original onto a substrate Device manufacturing method.