JPH11274029A - Scanning stepper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve scanning precision of a scanning stepper. SOLUTION: A wafer stage of a scanning stepper is divided into a stepping stage for movement in reticle unit and a scanning stage for movement within an exposure region. As the stepping stage, a Y-stage 5 and an X-stage 6 are provided. As the scanning stage, Y-stage (or X-stage) 8 is provided. An ultrasonic wave motor is employed as a drive motor for the scanning stage 8. With this method, since the wafer stage is divided into a stepping stage and an scanning stage, and the driving mechanism of the scanning stage with smaller moving range is made more accurate than that of the stepping stage, so the scanning accuracy is enhanced while the cost is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduction projection exposure apparatus (stepper) used in a manufacturing process of a semiconductor device, wherein one reticle pattern is transferred by moving a wafer and a reticle within an exposure area. The present invention relates to a scanning stepper that transfers a large number of reticle patterns to the entire wafer by repeatedly moving a wafer in reticle units after exposure.

[0002]

2. Description of the Related Art A stepper is an apparatus for transferring a large number of reticle patterns onto the entire wafer by exposing a reduced projection image of the reticle pattern to a predetermined position on the wafer while moving the wafer in reticle units. There are an apparatus for transferring the entire pattern by one exposure, and an apparatus for exposing the transfer of one reticle pattern by moving a wafer and a reticle within an exposure area. The latter apparatus is called a scanning stepper, and is expected as an exposure apparatus for a miniaturization process of 0.25 μm or less for mass production.

In a scanning stepper, a light irradiation area on a reticle is set to, for example, an elongated rectangle, so that light is irradiated not on the entire reticle but on a part thereof in the X direction or the Y direction. Exposure is performed in units. Then, in order to perform scan exposure on the entire reticle in units of the light irradiation region, it is necessary to move the exposure region of the reticle (the region arranged in the light irradiation region and exposed). for that reason,
The scanning stepper moves the reticle X within the exposure area.
A reticle stage for moving in the direction or the Y direction is provided.

When the exposure area of the reticle is moved, the exposure area of the wafer to be transferred must also be moved in the same direction in synchronization with the movement of the reticle. However, since a reduced projection image of the reticle pattern is formed on the wafer, the amount of movement of the wafer synchronized with the reticle is a value obtained by multiplying the amount of movement of the reticle by the reduction ratio.

As described above, the movement of the wafer by the scanning stepper, except for the movement associated with the alignment, is as shown in FIG. 4 in a reticle unit (stepping) and in the exposure area (stepping). Scanning). Here, the range of the stepping is the whole wafer, but the range of the scanning is the range in the reticle. Therefore, the moving range of the stage is much smaller in scanning than in stepping.

As shown in FIG. 5, the conventional scanning stepper includes an optical system 1 for condensing light from a light source on a light irradiation area A on a reticle R, a reticle stage 2, and a light transmitted through the reticle R. It comprises an optical system 3 for reducing and projecting on a wafer W, and a wafer stage 4.

As a conventional wafer stage, for example, as shown in FIG. 6, a Y stage 5 for moving a wafer W in a Y direction, an X stage 6 for moving in a X direction, a Z stage 7 for moving in a Z direction, and a stage There is a θ stage 9 that performs a rotational movement about a predetermined point in the plane from the bottom in this order, and a wafer chuck 10 is provided on the θ stage 9.

Conventionally, in the movement of the two wafers, the stepping is performed on the Y stage 5 of the wafer stage.
And / or X stage 6 with scanning Y
Performed on stage 5 or X stage 6. Also, Y
The drive mechanism of the stage 5 and the X stage 6 is D
A combination of a C motor and a ball screw or a combination of a linear motor and an air bearing is employed, and the accuracy is 0.02 μm to 0.05 μm.

[0009]

However, the accuracy required for moving the wafer in the scanning stepper is higher in scanning than in stepping. For example, the required accuracy of stepping in a certain process is about 0.04 μm, but ultra-high accuracy of about 0.01 to 0.02 μm has come to be required as the scanning accuracy. Therefore, the Y stage and the X stage used in the conventional wafer stage are required to have improved scanning accuracy.

[0010] The present invention is to solve such a problem of the prior art, and it is an object of the present invention to improve the scanning accuracy of a scanning stepper.

[0011]

In order to solve the above-mentioned problems, the present invention provides a scanning apparatus having a reticle stage for moving a reticle in an exposure area, and a wafer stage for moving a wafer in reticle units and in the exposure area. In the stepper, the wafer stage has a stepping stage that moves in reticle units and a scanning stage that moves in the exposure area separately, and the driving mechanism of the scanning stage has higher precision than the driving mechanism of the stepping stage. The present invention provides a scanning stepper characterized in that:

The improvement of the scanning accuracy can also be achieved by making at least one of the driving mechanism of the X stage and the Y stage of the conventional wafer stage higher in accuracy than the conventional one. However, in this configuration, there is a problem in terms of cost because the moving range of the stage as a high-precision drive mechanism is large.

On the other hand, according to the present invention, the wafer stage is divided into a stepping stage and a scanning stage, and the driving mechanism of the scanning stage having a small moving range has a higher precision than the driving mechanism of the stepping stage. Scanning accuracy can be increased while suppressing costs.

In the scanning stepper of the present invention, it is preferable that the driving motor of the scanning stage is an ultrasonic motor. Thereby, a scanning accuracy of about 0.01 μm can be obtained.

In the scanning stepper according to the present invention, a stage other than the θ stage for rotating and moving within the stage surface is provided below the scanning stage on the scanning stage, and a wafer support table is provided on the upper surface of the θ stage. Is preferably installed in an embedded state.

In order to ensure the accuracy of the scanning stage, it is necessary to minimize the load applied to the scanning stage. However, by installing a θ stage having a wafer support pedestal mounted on the scanning stage,
The load on the scanning stage can be minimized.

In the scanning stepper of the present invention, it is preferable that the drive motor of the reticle stage is an ultrasonic motor. Thereby, a reticle movement accuracy of about 0.01 μm can be obtained.

[0018]

Embodiments of the present invention will be described below. Note that the scanning stepper of this embodiment is characterized by a wafer stage, and portions other than the wafer stage are configured in a conventional manner.

As shown in FIG. 1, the wafer stage of this embodiment includes a Y stage 5 for moving a wafer in the Y direction, an X stage 6 for moving the wafer in the X direction, a Z stage 7 for moving the wafer in the Z direction, and an X stage ( Or Y stage)
8, and a θ stage 9 for performing rotational movement about a predetermined point on the stage surface in this order from the bottom, and a wafer chuck (wafer support table) 10 is embedded in the upper surface of the θ stage.

The Y stage 5 and the X stage 6 are stepping stages. Like the Y stage 5 and the X stage 6 used in the wafer stage of the conventional scanning stepper, a linear motor and an air bearing are used as a linear driving mechanism. The combination is adopted. The X stage (or Y stage) 8 is a scan stage, and employs a linear ultrasonic motor as a linear drive mechanism.

As shown in FIG. 2, a concave portion 9 for embedding a wafer chuck 10 is formed on the upper surface of the θ stage 9.
The wafer chuck 10 is inserted into the recess 91, and the center of the wafer chuck 10 is fixed by a bolt 92. Further, the wafer chuck 10 supports the wafer W in a suction state by placing the wafer W on the upper side and vacuum-suctioning the wafer W downward. Therefore, when the wafer chuck 10 supports the wafer W in a suction state, the wafer chuck 1
0 is attracted to the bottom surface of the concave portion 91 of the θ stage 9. The wafer chuck 10 is securely fixed in the θ stage 9 by the suction force. Note that, between the θ stage 9 and the X stage (or Y stage) 8, a bearing 11 for rotational driving in the circumferential direction of the wafer is provided.

As shown in FIG. 3, the wafer chuck 10 includes a rod-shaped elevating member 12 for receiving the wafer W on the upper surface. As shown in FIG. 3A, the elevating member 12 is configured to descend when the wafer W is sucked, and to ascend when attaching and detaching the wafer W as illustrated in FIG. 3B. When the wafer W is removed, the hand of the robot arm is inserted into the gap between the raised wafer W and the wafer chuck 10, and the wafer W is lifted.

The drive control mechanism and the position detection mechanism of each stage are configured so that the movement accuracy of each stage is sufficiently ensured. As described above, in this embodiment, the X stage (or Y stage) 8 corresponding to the scanning stage is provided separately from the Y stage 5 and the X stage 6 corresponding to the stepping stage, and is driven by the linear ultrasonic motor. Because
Scanning of the wafer W can be performed with ultra-high accuracy of about 0.01 μm. The Y stage 5 and the X stage 6 corresponding to the stepping stage are driven by a mechanism combining a linear motor and an air bearing. According to this mechanism, the stepping accuracy of the wafer W is about 0.03 μm. Is obtained.

In this embodiment, as compared with the case where the driving mechanism of the Y stage 5 or the X stage 6 is a linear ultrasonic motor without providing the X stage (or Y stage) 8, By using a linear ultrasonic motor as the drive mechanism for only the small scanning stage, it is possible to increase the scanning accuracy while suppressing costs. In addition, an increase in the number of stages is expected to improve the throughput.

[0025]

As described above, according to the present invention,
By making the driving mechanism of the scanning stage only ultra-high-precision, it is possible to increase the scanning accuracy while suppressing costs. In addition, an increase in the number of stages is expected to improve the throughput.

In particular, according to the third aspect of the present invention, the load on the scanning stage can be minimized, so that the scanning accuracy of the drive mechanism used can be maximized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a wafer stage according to an embodiment.

FIG. 2 is a schematic enlarged sectional view showing a relationship between a θ stage and a wafer chuck.

FIG. 3 is a schematic cross-sectional view for explaining the movement of a wafer chuck.

FIG. 4 is a plan view of a wafer for explaining a difference between scanning and stepping.

FIG. 5 is a schematic configuration diagram showing a conventional scanning stepper.

FIG. 6 is a schematic configuration diagram showing a conventional wafer stage.

[Explanation of symbols]

Reference Signs List 1 optical system for light irradiation 2 reticle stage 3 optical system for reduction projection 4 wafer stage 5 stepping stage (Y stage) 6 stepping stage (X stage) 7 Z stage 8 scanning stage (X stage or Y stage) 9 θ stage 10 wafer Chuck (wafer support) 91 recess A light irradiation area R reticle W wafer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/30 516B

Claims (4)

[Claims] 1. A scanning stepper having a reticle stage for moving a reticle in an exposure area and a wafer stage for moving a wafer in reticle units and in the exposure area, wherein the wafer stage is moved in reticle units. A scanning stepper having a stage and a scanning stage for moving within an exposure area separately, wherein a driving mechanism of the scanning stage has a higher precision than a driving mechanism of the stepping stage. 2. The scanning stepper according to claim 1, wherein the driving motor of the scanning stage is an ultrasonic motor. 3. The wafer stage has a stage other than a θ stage that performs rotational movement within a stage surface below the scanning stage, and a wafer support is installed in an embedded state on the upper surface of the θ stage. 3. The scanning stepper according to claim 1, wherein 4. The scanning stepper according to claim 1, wherein a drive motor of the reticle stage is an ultrasonic motor.