JPH04328820A - Semiconductor aligner - Google Patents

Abstract

PURPOSE:To provide the title semiconductor aligner capable of controlling exposure value with high precision in a simple constitution thereby enabling specified exposure value to be easily gained. CONSTITUTION:The title semiconductor aligner, which performs reduction projection of a pattern on a reticle 8 on a wafer 10, is provided with a detection means (circut) 5, the first and second shielding sheets 17, 18 successively traversing the exposing light in the same direction for shielding the same, a detection means detecting the size of an opening part formed by the shielding sheets 17, 18, a control means (circuit) 6 controlling the size of the opening part as well as a process control means 7 processing the proper size of the opening conforming to the detected exposure value and the size of opening part so that the relative positions of the first and second shielding sheets 17, 18 may be mutually fluctuated by the control means 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor exposure apparatus that performs exposure by rotating two rotary plates in the same direction while changing the aperture ratio to a suitable exposure amount.

0002

2. Description of the Related Art In a conventional semiconductor exposure apparatus, an opening is provided in one rotating plate, and exposure is performed by driving and stopping the rotating plate at high speed. As one example of a structure for increasing the opening/closing speed of the rotary plate, two blades are provided, and these blades are rotated in opposite directions to perform exposure.

0003

However, in the prior art described above, the rotary plate must be driven and stopped repeatedly at high speed for each exposure, requiring a complicated control circuit. Furthermore, in order to increase the efficiency of the opening and closing operations by the rotary plate, the intervals and pitches between the openings and non-opening parts of the rotary plate are made as small as possible. For this reason, the rotational positioning of the rotary plate must be performed with high precision, making the positioning control circuit complicated.

Furthermore, since the aperture is fixed, the amount of exposure obtained by opening and closing one aperture is inversely proportional to the rotational speed, and this rotational speed has an upper limit. Therefore, it was not possible to obtain an exposure amount less than the amount determined by the rotation speed.

The present invention has been made in view of the above-mentioned shortcomings of the prior art, and aims to provide a semiconductor exposure apparatus that enables highly accurate exposure control with a simple configuration and that can easily obtain a desired exposure amount. shall be.

[0006]

[Means and operations for solving the problems] In order to achieve the above object, the present invention provides an aperture ratio variable mechanism on one of the two rotary plates, so that the two rotary plates can be moved in the same direction at the same time. Rotate at high speed. This allows highly accurate exposure control to be performed without repeating high-speed driving and stopping operations. Also,
By providing a light amount sensor and a drive unit for the variable aperture ratio mechanism, constant control of minute exposure amounts becomes possible.

[0007]

Embodiment FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, 1 is an exposure light source, 2 is a variable exposure shutter equipped with two rotary plates, 3 is an optical path, 4 is an exposure sensor, 5
6 is a light amount detection circuit, 6 is a rotary plate control circuit for the variable exposure amount shutter 2, 7 is an arithmetic unit, 8 is a reticle, 9 is a projection lens, 10 is a wafer, and 11 is a wafer stage.

FIG. 2 is a detailed perspective view of the variable exposure shutter 2. As shown in FIG. In FIG. 2, 12 indicates two rotating plates 17 and 18.
a drive motor for rotating the 13, 14, 15, 1
Reference numeral 6 denotes a transmission gear for transmitting rotational motion to the two rotary plates. Gears 14 and 16 are constituted by ordinary spur gears and drive the rotary plate 17. Gears 13 and 15 are composed of worm gears and drive rotary plate 18. Reference numeral 19 denotes a connecting fitting that connects the worm gear 15 and the ball screw 20, and moves the worm gear 15 in the thrust direction. 21 is a drive motor that rotates the ball screw 20, and 22 and 23 are encoders attached to each motor 21 and 12.

Next, the operation of the variable exposure shutter configured as shown in FIG. 2 will be explained with reference to FIGS. 3, 4, and 5. In each figure, (A) shows the structure of the entire shutter, and (B) shows the mutual positional relationship of the two rotary plates.

In FIG. 3, a rotating plate 18 is connected to a worm gear 15, and a rotating plate 17 is connected to a spur gear 16.
is a state in which the four notches of each rotating plate overlap. When the drive motor 12 is rotated in this state, the two rotary plates 17 and 18 rotate with their notches overlapped.

Next, as shown in FIG.
is rotated to drive the worm gear 15 via the ball screw 20 and the connecting fitting 19 to move it in the direction of the arrow in FIG. 4(A). At this time, the rotating plate 17 connected to the spur gear 16 does not rotate. On the other hand, since the rotary plate 18 connected to the worm gear 15 rotates as the worm gear 15 moves in proportion to the amount of movement of the coupling fitting 19, the rotary plate 18 also rotates. Therefore, as shown in FIG. 4(B),
The notch of the rotary plate 18 is shifted from the notch of the rotary plate 17. That is, the area of the notch is reduced and the aperture ratio is reduced. When the drive motor 12 is rotated with the worm gear 15 in this position, the two rotating plates 17
, 18 rotate with the notch area reduced by approximately half.

Next, as shown in FIG. 5(A), when the connecting fitting 19 is further moved in the direction of the arrow by the drive motor 21, as shown in FIG. 5(B), the two rotary plates 17, 1
8 is further shifted and the notch becomes completely closed.

The variable exposure shutter 2 having the configuration shown in FIG. 2 is arranged in the optical path of the exposure apparatus having the configuration shown in FIG. ), Figure 3 shows the shutter open state with 100% exposure,
5 shows a shutter closed state with an exposure amount of 0%, and FIG. 4 shows a shutter open state with an arbitrary aperture ratio of an exposure amount of 0 to 100% depending on the position of the connecting fitting 19.

The operation of the exposure apparatus according to the present invention in which the variable exposure shutter configured as described above is disposed in the optical path will be described below.

First, the wafer 10 is moved to a position for exposure using the wafer stage 11. While the wafer is being moved, the rotary plate is rotated so that the variable exposure shutter 2 has an aperture angle of 0° as shown in FIG. 5 so that the wafer is not exposed to exposure light. When the exposure position is determined, a signal indicating completion of exposure preparation is transmitted from the wafer stage control device 25 to the controller 26, a signal to start exposure is transmitted from the controller 26 to the arithmetic and control device 7, and a signal to open the shutter is transmitted from the arithmetic and control device 7. The information is transmitted to the board control circuit 6. As a result, the drive motor of the variable exposure shutter 2 is operated so that the aperture angle of the rotating plate is maximized, as shown in FIG.

The light passing through the variable exposure shutter 2 is reflected by a half mirror 24, and the light amount is measured by a light amount sensor. The light at this time is pulsed light that is repeatedly blocked and transmitted by the rotating plate, so the light intensity of each pulse of light is measured, and the sum of each exposure amount is calculated in advance by the controller.
The appropriate exposure amount set from step 6 is compared and calculated by the arithmetic and control unit as needed, and as the sum of the exposure amounts approaches the appropriate value, the rotating plate control circuit gradually adjusts the aperture angle of the rotating plate as shown in FIG. When the exposure amount is changed to a small value and the exposure amount reaches the same value as the appropriate value, the exposure amount variable shutter 2 is closed as shown in FIG.

The process from the start of exposure to the end of exposure will be explained in more detail below.

First, when an exposure start signal is received, the motor 21 is driven to move the worm gear 15 forward as shown in FIG. At this time, the rotating plate 18, as shown in FIG. 3(B),
It overlaps with the rotary plate 17, and the aperture angle becomes maximum, resulting in the maximum exposure amount of light. First, the exposure amount of the first pulse (temporarily assume A)
is measured, and the arithmetic device calculates how many pulses (tentatively assumed to be N+Δn) are required to complete the exposure for the optimum exposure amount at that time (temporarily assumed to be B) (B/A=N+Δn).

The encoder 23 attached to the motor 12 is a speed detection sensor for rotating the rotary plates 17 and 18 at a constant speed, and at the same time constantly detects subtle changes in the constant speed rotation and detects the changes. Add or subtract from Δn, which is the final exposure amount. If the calculated Δn is a decimal number, the calculation device 7 calculates the aperture angle of the rotary plate 18 for the exposure amount of Δn, and the worm gear 15 is placed in the position to obtain that aperture angle, and the encoder 22 and motor 21 to control the position and move it as shown in FIG. When this controlled aperture angle crosses the exposure light and the exposure amount of Δn is exposed, the motor 21 is driven again to close the shutter as shown in FIG. 5 and send a signal indicating the end of exposure to the controller.

When the exposure completion signal is transmitted to the controller, the controller sends the exposure completion signal to the wafer stage control device to move the wafer stage to the next exposure position. As described above, by using a variable exposure shutter, rotating it at high speed, and controlling the aperture angle of the shutter while constantly monitoring the exposure, the complex control associated with driving and stopping the shutter can be achieved. This eliminates the need for fine exposure control.

Although the above embodiment uses a worm gear to drive the rotary plates, it may be possible to use a configuration in which the rotary plates 17 and 18 are directly driven by each motor to control the aperture angle without using a worm gear.

Further, in the above embodiment, the variable exposure shutter rotates all the time, but it does not rotate all the time; for example, in the above example, when A/B=N+Δn, the shutter is rotated until the exposure amount reaches (N-1) times. In the open state, stop rotating and expose (1+
Exposure may be performed while controlling the aperture angle and rotating the exposure amount for Δn) times.

[0023]

As explained above, in the variable exposure shutter according to the present invention, exposure is performed by rotating the two rotary plates at high speed and controlling the aperture angle of the shutter while constantly monitoring the exposure amount. This eliminates the need to frequently drive and stop the shutter at high speed, resulting in a longer mechanical life.
Moreover, a complicated control circuit is not required. Additionally, in the past, the aperture angle of the shutter was fixed, so it was not possible to obtain an exposure amount below that aperture angle, but with the present invention, the aperture angle can be freely controlled, allowing highly accurate exposure control and allowing arbitrary exposure amounts to be obtained. Obtained with high precision.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an exposure apparatus according to the present invention.

[Figure 2]
2 is a detailed diagram of a variable shutter section of the exposure apparatus in FIG. 1. FIG.

3 is an explanatory diagram of the operation of the variable shutter in FIG. 2 when it is fully open; (A) shows the shutter side structure, and (B) shows the front view of the rotary plate; FIG.

4 is an explanatory diagram of the operation of the variable shutter in FIG. 2 when it is opened in the middle; (A) shows the shutter side structure, and (B) shows the front view of the rotary plate; FIG.

5 is an explanatory diagram of the operation of the variable shutter in FIG. 2 when fully closed; (A) shows the shutter side structure, and (B) shows the front view of the rotary plate; FIG.

[Explanation of symbols]

1 Exposure light source 2. Variable exposure shutter 4 Exposure sensor 5 Light amount detection circuit 8 Reticle 10 Wafer 13, 15 Worm gear 14, 16 Spur gear 17, 18 Rotating plate

Claims (2)

[Claims] 1. A semiconductor exposure apparatus that projects a pattern on a reticle in a reduced size onto a wafer, comprising means for detecting the amount of exposure light, and first and second light shielding plates that sequentially pass and block the exposure light from the same direction. and means for detecting the size of the aperture formed by the light shielding plate; and means for controlling the size of the aperture; 1. A semiconductor exposure apparatus, comprising: arithmetic means for calculating an appropriate opening size based on the control means, and wherein the relative positions of the first and second light shielding plates are changed by the control means. 2. The first and second light-shielding plates are composed of two rotating plates provided coaxially, each rotating plate having a plurality of notches, and a light-shielding plate having a shape corresponding to the amount of overlap between the notches. 2. A semiconductor exposure apparatus according to claim 1, wherein the aperture ratio for exposure light is variable from 0 to 100%.