JPS62199031A - Exposure device - Google Patents

Abstract

PURPOSE:To correct the position of a stage by irradiating a wafer on the stage by a luminous element through a mask and calculating an OFF position based on electric signals corresponding to the difference in intensity of the reflected lights from the stage, wafer, and mask so as to move the stage. CONSTITUTION:Light emission of a LED 53 is controlled by a control circuit 57 including a calculator and a wafer 33 on a stage 41 is irradiated through a mask 49 having a mark 51. The reflected lights from the stage 41, wafer 33, and mark 51 on the mask are detected by a CCD 55 which converts them into electric signals and sends them to the control circuit 57. As the intensity of the reflected light from the mark 51 is different from that from the stage or wafer, a circuit 27 determines the position of the mark 51 based on an electric signal corresponding to the difference in intensity. Also, the reflected light intensity of the wafer is different from that of the stage and the OFF position can be determined based on an electric signal corresponding to the intensity difference. The control circuit drives pulse motors 43 and 45 to set the wafer at the optimum position.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an exposure apparatus, and particularly to an alignment means for an exposure apparatus used in the manufacturing process of semiconductor devices.

<Prior Art> FIG. 4 is a front view showing a schematic configuration of a conventional exposure apparatus. First, the conventional example will be explained. 1 is a pre-alignment station, and this pre-alignment station 1 includes a conveyor (not shown). ) the wafer 3 is supplied. Wafer 3 on pre-alignment station 1
The position of the wafer 3 is adjusted while being lifted by an air bearing, and the orientation flat 5 formed on the wafer 3 is aligned with a predetermined position on the pre-alignment station 1.

Reference numeral 7 indicates a drive arm that supports the vacuum tweezers, and rotates in the direction of the arrow to carry the wafer 3 on the pre-alignment station 1 into the exposure apparatus 9. The exposure apparatus 9 has a movable stage 1 on which the wafer 3 carried in is placed.
1, and this movable stage 11 is movable in two orthogonal axes directions by pulse motors 13 and 15. 17
1 shows an optical system of the exposure device R9, which transfers a pattern formed on a glass mask (not shown) set in the optical system 17 onto the wafer 3 on the movable stage 11.

Preflight station 1 and movable stage 1 above
1 is the X-direction adjustment micrometer 19 provided in the pre-alignment station 1.
The Y-direction adjustment micrometer 21 and the tilt adjustment micrometer 23 are used to move or rotate the preflight station 1 in the respective directions for adjustment.

<Problems to be Solved by the Invention> Generally, in the manufacturing process of semiconductor devices, a plurality of alignment marks are printed on the wafer 3 in the first exposure process, and in the subsequent exposure process, patterns are created on the wafer 3 based on these alignment marks. Layer them one by one. However, in the first exposure process, the movable stage 11 must be moved and aligned while observing the scrub lines formed on the wafer 3 with a microscope, and the relative position between the pre-alignment station 1 and the movable stage 11 must be adjusted. If the position is significantly out of alignment, the wafer 3 will be greatly deviated from the field of view of the microscope when the drive arm 7 transports the wafer 3 from the pre-alignment station 1 to the movable stage 11, making it difficult to align the wafer 3 for the first exposure process. There was a risk of making a mistake.

In order to eliminate errors in such positioning, it is necessary to ensure accurate relative positioning between pre-alignment station 1 and movable stage 11. X-direction shoulder adjustment micrometer 19, Y-direction adjustment micrometer 21, and tilt adjustment micrometer 2
3, the adjustment becomes complicated and the relative positioning of the pre-alignment station 1 and the movable stage 11 cannot be performed frequently.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an exposure apparatus that can tolerate errors in relative position between a pre-alignment station and a stage of an exposure apparatus and can accurately adjust the position of a wafer in the first exposure process.

<Means for Solving the Problems> The present invention provides a stage that supports a wafer having an orientation flat and is movable in multiple directions, and an optical exposure system that supports a mask and transfers a pattern formed on the mask onto the wafer. The exposure apparatus further includes a light emitter that irradiates light that can reach the stage through the transparent portion of the mask, and a light receiver that outputs an electric signal corresponding to the intensity of one reflected light, A mark that generates reflected light with a different intensity from the reflected light from the stage and the reflected light from the wafer is attached to the mask in correspondence with the reference position, and the reflected light reflected from the stage and the reflected light from the wafer are attached. Calculating means for calculating the position of the orientation flat on the stage based on an electric signal corresponding to the intensity difference between the reflected light and the reflected light reflected by the mark, and moving the stage based on the calculation result to correct the position of the wafer. It is characterized by having the following.

Functions and Effects> The exposure apparatus with the above configuration emits light from one light emitter through a mask onto a wafer placed on a stage, and emits reflected light from marks placed on the stage, wafer, and mask. The photoreceptor converts the reflected light into an electrical signal proportional to its intensity. This is because the intensity of the reflected light reflected from the marks attached to the mask is different from the intensity of the reflected light reflected from the stage and wafer.

The calculation means determines the position of the mark based on the electrical signal corresponding to the intensity of the reflected light. In addition, since the wafer has a mirror finish, the intensity of the reflected light reflected by the wafer is different from the intensity of the reflected light reflected by the stage, and the calculation means uses electrical signals corresponding to the intensities of these reflected lights to The orientation of the flat position can be determined. Therefore, the calculation means can determine the position of the orientation flat of the wafer with respect to the position of the mark, and by associating the mark position with a predetermined position of the stage in advance, the position of the orientation flat on the stage can be determined. I can do it. If the position of the orientation flat on the stage can be determined in this way, the stage can be moved to position the wafer at a desired position. As a result, the wafer can always be positioned at the optimum position, and a mask pattern can be printed at a predetermined position on the wafer.

<Embodiment> FIG. 1 is a schematic front view showing the configuration of an embodiment of the present invention, and numeral 31 indicates a pre-alignment station. A wafer 33 is supplied to this pre-alignment station 31 by a conveyor (not shown). The position of the wafer 33 on the pre-alignment station 31 is adjusted while being floated by an air bearing, so that the orientation flat 35 formed on the wafer 33 is aligned with a predetermined position on the pre-alignment station 31.

Reference numeral 37 indicates a drive arm that supports the vacuum tweezers, and rotates in the direction of arrow B to carry the wafer 33 on the pre-alignment station 31 into the exposure apparatus f[39. Exposure device! 39 has a movable stage 41 on which the loaded wafer 33 is placed, and this movable stage 41 is movable in two orthogonal directions by pulse motors 43 and 45.

Reference numeral 47 indicates an optical system of the exposure device W139, which transfers the pattern formed on the glass mask 49 set in the optical system 47 onto the wafer 33 on the movable stage 41. This pattern is formed by etching a chromium film or the like on the surface of the transparent body, and at this time, a mark 51 for defining a reference position and an alignment mark are also formed.

The optical system 47 is provided with a light emitter 53 and a light receiver 55, and the light emitter 53 is connected to the wafer 3 through a glass mask 46.
It is composed of a group of light emitting diodes with a sufficient amount of light to illuminate the movable stage 3 and the movable stage 41 around it. On the other hand, the photoreceptor 55 is composed of an image sensor such as a CCD, and outputs an electric signal having a value corresponding to the amount of light received for each pixel.

The light emitter 53 emits light in response to a command signal from a control circuit 57, and the electric signal output from the light receiver 55 is transmitted to the control circuit 57.
Sent on 7th. This control circuit 5.7 is composed of a microcomputer system, and controls the pulse motor 4.
It also includes 3.45 drive circuits.

Reference numeral 59 denotes a microscope for observing the movable stage 41, and this microscope allows the orientation flat 3
If you observe the area around 5, you will see something like Figure 2.

Next, FIG. 3(a) shows the operation of the above embodiment.

This will be explained with reference to the flowchart in (b).

First, in the start switch-on event, the light emitter 53 is turned on (step a), each pixel of the photoreceptor 55 is scanned (step b), and in scanning each pixel, an electric signal output from each pixel is Step c) to determine whether or not is the maximum value, if the determination result in step C is no,
determining whether the electrical signal has a minimum value (step d);
When the determination result in step d is YES, the minimum value Dmin is given to the pixel that outputs the electric signal.Step e)
, if no, an intermediate value Dint is given (step f). Based on this, when the determination result in step C is YES, the minimum value D m a is applied to the pixel that outputs the electric signal.
x, (step g). These steps f
After Be fe g, each value Dmin,.

D in t, , Dmax, are written to memory (
step h), the orientation flat 35 of the wafer 33 based on the intermediate value Dint and the minimum value Dmin;
is determined (step i), followed by the maximum value D
max, and the intermediate value Dint.

Alternatively, the position of the mark 51 is determined based on the minimum value Dmin (step j), and these steps 1yJ
Step k) Calculate the deviation between the orientation flat 35 and the mark 51, that is, the reference position, based on the results of
, instructs the rotation angle to the pulse motors 43, 45 in order to correct the deviation (step k).

Thus orientation flat 35 and mark 51
When these match, the movable stage 41 of the wafer 33 is positioned at the reference position, and the pattern of the glass mask 49 is burned onto the wafer 33. At this time, an alignment mark is also placed at a predetermined position on the wafer 33.

[Brief explanation of drawings]

Fig. 1 is a schematic front view showing the configuration of an embodiment of the present invention, Fig. 2 is an enlarged plan view showing a part of the field of view of the microscope, and Fig. 3 (
a) to (b) are flowchart diagrams for explaining the operation of one embodiment, and FIG. 4 is a schematic front view of a conventional example. 33...Wafer. 35... Orientation flat. 41... Stage, 49... Mask, 51... Mark, 53... Light emitter, 55... Light receiving body, 57... control means. Patent Applicant: ROHM Co., Ltd. Agent, Patent Attorney: Kiyoshi Kuwai - Figure 2, Figure 3 (b)

Claims (1)

[Claims] In an exposure apparatus that includes a stage that supports a wafer having an orientation flat and is movable in multiple directions, and an optical exposure system that supports a mask and transfers a pattern formed on the mask to the wafer, A light emitter that emits light that can reach the stage through the part and a light receiver that outputs an electrical signal corresponding to the intensity of the reflected light are further provided, and the mask is provided with a light emitter that emits light that can reach the stage and a light receiver that outputs an electrical signal corresponding to the intensity of the reflected light. A mark that generates reflected light with a different intensity from the light is attached in correspondence with the reference position, and the reflected light reflected by the stage, the reflected light reflected by the wafer, and the reflected light reflected by the mark are combined. An exposure apparatus comprising a calculation means for calculating the position of an orientation flat on a stage based on an electric signal corresponding to an intensity difference, and moving the stage based on the calculation result to correct the position of the wafer.