JPH03211811A - Exposure aligner - Google Patents

Abstract

PURPOSE:To realize high precision projection baking, by using a light shielding plate having an aperture as an element of an illuminating system, and a photo detecting means having a light receiving surface of a specified size, and constituting each element in the manner in which a measurement surface is scanned with a projection image, formed by a projection optical system, of the aperture of the light shielding plate. CONSTITUTION:A photo detecting means 13 having a light receiving surface of a specified size is arranged in a space on the projection surface side of a projection optical system; an aperture 2a of a light shielding plate 2 is moved in a plane perpendicular to the optical axis of an illuminating system 1, thereby measuring the illuminance and/or the illuminance distribution at arbitrary positions on the projection surface of the projection optical system. Hence the illuminance of an arbitrary position can be accurately measured without accurately aligning the light receiving surface to a wafer 9 surface or an image surface of the projection optical system. Thereby an aligner capable of rapidly and highly precisely measuring the illuminance and the illuminance distribution and available for high resolution projection baking can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an exposure apparatus for semiconductor manufacturing, and more particularly, to an exposure apparatus for semiconductor manufacturing, in which a circuit pattern formed on the entire surface of a reticle is projected onto a wafer surface, which is a projection surface, by a projection optical system. The present invention relates to an exposure apparatus equipped with an illuminance measuring means for measuring the illuminance and illuminance distribution within the projection plane during projection exposure at a magnification of .

(Conventional technology) In recent semiconductor manufacturing technology, the resolution pattern line width has become less than 1 μm due to the high integration of electronic circuits, and there is a demand for optical exposure equipment with higher resolution than before. has been done.

Generally, when projecting a circuit pattern on a reticle surface onto a wafer surface (projection surface) via a projection optical system, the resolution line width of the circuit pattern is determined on the projection surface along with the wavelength used and the N, A, etc. of the projection optical system. The quality of the illuminance distribution greatly affects the quality of the image.

For this reason, in many conventional exposure apparatuses, the X
An illuminance meter is placed on or near the Y stage surface, and the illuminance distribution on the projection surface is measured by various methods.

For example, (a) a method in which an illumination meter is attached to a part of the XY stage on which the wafer is placed, and the illumination meter on the XY stage is moved onto the projection plane as necessary to measure the illuminance distribution.

(b) A method in which an illuminance meter is placed on a part of the XY stage surface each time a measurement is made, and the illuminance distribution within the projection plane is measured while moving the XY stage.

etc. are used.

(Problems to be Solved by the Invention) Among the methods for measuring the illuminance distribution on the projection plane, the method (a) above uses the XY
As the stage becomes larger, the driving force of the XY stage increases. For this reason, if you try to set the moving speed (acceleration) to the same value as before installing the illumination meter, the excitation force of the XY stage will increase, the vibration of the entire device will increase, the alignment accuracy will decrease, and the resolution will decrease. I'll come. Another problem is that if the exposure apparatus waits until the vibrations of the exposure device subside, the throughput decreases.

Another problem is that the illumination meter placed on the XY stage must be moved over the entire projection area, which increases the movable stroke of the XY stage and increases the processing range of the XY stage, making it difficult to move with high precision. was there.

On the other hand, the method (b) above prevents the XY stage from becoming larger and the movable stroke from increasing, but the wafer chuck must be removed and the illumination meter must be mounted on the XY stage surface each time measurements are taken. There is a problem in that the throughput decreases and the parallelism between the wafer chuck and the projection plane of the projection optical system changes due to the reversal of the wafer chuck attachment/detachment operation, resulting in a decrease in resolution.

The present invention is based on a light blocking plate (masking blade) having an opening that regulates the irradiation range and amount of irradiation onto the irradiated surface, which is one element of the illumination system in the exposure apparatus, and which is the reticle surface, and By using a light detection means having a light-receiving surface of a predetermined size and placed at a predetermined position, the illuminance and illuminance distribution within the projection plane can be measured quickly and with high precision, allowing for high-resolution projection printing. The purpose is to provide an exposure device that is capable of

(Means for Solving the Problems) The exposure apparatus of the present invention illuminates a projection object placed on an irradiated surface with a light beam from an illumination system through a light-shielding plate having an aperture with a variable aperture area, In an exposure apparatus in which the projection object is projected onto a projection surface at a predetermined magnification by a projection optical system,
A light detection means having a light receiving surface of a predetermined spatial size is arranged on the projection surface side of the projection optical system, and the opening of the light shielding plate is moved within a plane perpendicular to the optical axis of the illumination system. Accordingly, the present invention is characterized in that an illuminance measuring means is provided to measure the illuminance and/or the illuminance distribution at any position on the projection plane by the projection optical system.

This feature allows the illuminance at any position to be accurately measured without having to precisely align the light receiving surface with the wafer surface or the image plane of the projection optical system.

(Example) FIG. 1 is a perspective view of essential parts of a first embodiment of the present invention.

In the figure, reference numeral 1 denotes an illumination system, which uniformizes and emits a luminous flux from a light source such as an ultra-high pressure mercury lamp or an excimer laser. 2 is a light shielding plate (masking blade), which has an aperture 2a whose aperture area can be changed, and is used as a lighting system! A reticle 5, which is an irradiated surface that will be described later, partially passes the light beam from the reticle 5.
The irradiation area on the surface is limited. The light shielding plate 2 is configured to be movable within a plane perpendicular to the optical axis of the illumination system 1, or to be able to displace the position of the opening 2a within the perpendicular plane.

Reference numeral 3 denotes a driving means, which allows the light shielding plate 2 or the aperture 2a to move arbitrarily within the effective luminous flux within a plane perpendicular to the optical axis of the illumination system 1. 4 is a relay optical system, which includes an opening 2a of a light shielding plate 2 and a reticle 5 which is a projection object (illuminated object).
The patterns of and are in a conjugate relationship. On the surface F of the reticle 5, a circuit pattern to be projected and transferred onto the wafer 9 is formed on a reticle made of quartz or the like and enlarged several times.

6 is a reticle stage, on which the reticle 5 is placed. A reticle hunt 7 supplies the reticle 5 onto the reticle stage 6 and collects it from the reticle stage 6. 8 is a projection lens system, which reduces and projects the circuit pattern on the surface of the reticle 5 onto the wafer 9-F. ! 0
There is an XY stage on which a wafer 9 is placed, and is moved in the XY force direction within the projection plane by a drive means (not shown).

A wafer supply hand 11 supplies the wafer 9 onto the XY stage 10. A wafer collection hand 12 collects the wafer 9 from the XY stage 10.

Reference numeral 13 denotes a light detection means, which is placed on the surface of the XY stage 10, and in this embodiment, when the opening 2a of the light shielding plate 2 is fully opened, the projection surface ( It has a light-receiving surface with uniform sensitivity and a larger area than the irradiation range on the surface of the sea urchin. 14 is a control means, which controls the driving operation of each unit.

In this embodiment, when the circuit pattern on the surface of the reticle 5 is projected and exposed onto the wafer 9 by the projection lens system 8, the wafer supply hunt! 1 supplies the wafer 9 from a cassette (not shown) to the XY stage 10 and 1-.

The XY stage 10 on which the wafer 9 is placed is driven and controlled by the control means 14 to align the reticle 5 and the wafer 9.

Thereafter, the circuit pattern on the surface of the reticle 5 illuminated by the exposure light from the illumination system 1 is projected and exposed onto the surface of the wafer 9 using the projection lens system 8 .

At this time, the shape and position of the opening 2a of the light shielding plate 2 are controlled by the driving means 3 so that only the desired circuit pattern on the reticle 5 surface is projected onto the wafer 9 surface, thereby preventing exposure from unnecessary areas. Light is prevented from entering the projection optical system.

By repeating the process from alignment of the reticle 5 and wafer 9 to projection exposure multiple times, the circuit pattern on the surface of the reticle 5 is projected onto the entire wafer 9. After the projection exposure of the entire surface of the wafer 9 is completed, the wafer 9 is collected from the XY stage 10 by the wafer collection hand 12 and carried out of the apparatus.

Next, the illuminance within the projection plane by the projection lens system 8 or/
When measuring the illuminance distribution, the reticle 5 and the reticle stage 6 are carried out by the reticle hunt 7. Then, the XY stage 1o is moved so that the light receiving surface of the light detecting means 13 includes the entire surface projected by the projection lens system 8.

In this embodiment, when the size of the light-receiving surface of the light detection means 13 is set as described above and the aperture 2a of the light shielding plate 2 is fully opened, the irradiation area on the projection surface based on the aperture of the projection lens system 8 is detected by light. Set to be included within the light receiving surface of the means 13,
It is characterized in that the light detection means 13 is fixed.

Next, the driving means 13 adjusts the aperture diameter of the aperture 2a of the light shielding plate 2 so that the projected image of the aperture 2a on the projection surface (wafer) has a preset size, that is, a preset measurement range. I'm narrowing it down.

Then, the driving means 3 moves the aperture 2a of the light shielding plate 2 so that the projected image of the aperture 2a is located in the area to be measured within the projection plane by the projection lens system 8.

In such a configuration, the exposure light from the illumination system 1 has a luminous flux diameter limited to the size of the aperture 2a of the light shielding plate 2, and is transmitted via the relay system 4 to the projection lens system 8 by the light detection means 13.
The beam is incident on the surface (measurement position) with a predetermined diameter.

That is, a projected image of the aperture 2a is formed on the surface of the light detection means 13. Accordingly, in this embodiment, the illuminance in an arbitrary region within the projection plane is measured.

In addition, by moving the aperture 2a of the light shielding plate 2 using the driving means 3 so that the projected image of the aperture 2a moves within the projection plane, the illuminance of each point within the projection area can be changed by the amount of illuminance. The measurement of 1(i is allowed r1ε).

In this case, for example, the control means 14 controls 12 of the opening 2a.
If the illuminance at each position is sequentially measured while determining the positional coordinates of the 12 images on the wafer and recorded in a recording means, the illuminance distribution over the entire projection surface can be easily measured.

In this embodiment, the same effect can be obtained even if the reticle 5 and the light shielding plate 2 are arranged close to each other and the relay system 4 is omitted. Further, the same effect can be obtained by using a mirror system having a concave mirror and a convex mirror instead of the projection lens 8.

In this embodiment, if the size of the light-receiving surface of the light-detecting means 13 is insufficient to cover the entire irradiation area of the projection surface, or if there is uneven sensitivity due to the incident position of the light-receiving surface, first, the opening 2a Determine the aperture diameter and location. Thereafter, a laser beam is used to measure the movement of the xy stage in two-dimensional directions so that the projected image of the aperture 2a on the projection plane is projected into the light-receiving surface or onto a predetermined area within the light-receiving surface. The XY stage 10 may be driven and controlled using an interferometer, and the illuminance in that area may be measured. Then, the position of the opening 2a is variously changed, and the light-receiving surface of the light-detecting means 13 is moved accordingly by driving the XY stage.
The illuminance distribution at each point on the projection plane may be determined.

In order to reduce the setting error of the aperture area of the gobo plate and to measure the illuminance distribution on the projection plane more accurately, it is necessary to set the aperture area of the gobo plate to the same size as the aperture area image on the projection plane.
Alternatively, if a pinhole plate 31 as shown in FIG. 3 in which a plurality of smaller equal aperture areas are arranged in a grid pattern is placed on the light receiving surface of the light detecting means 13, the light detecting means 13
The illuminance and illuminance distribution on the projection plane can be determined while the

In the present invention, the light detection means 13 does not necessarily need to be placed on the surface of the XY stage 13 so that the light receiving surface and the exposure surface coincide with each other. It may be placed anywhere as long as it can receive all of the exposure light irradiating the surface.

FIG. 2 is a schematic diagram of a main part of an embodiment of the present invention when the light detection means 13 is arranged below the projection lens system 8 below the XY stage 1o.

In this embodiment, when measuring the illuminance and illuminance distribution within the projection plane by the projection lens system 8, the XY stage 10 is retracted to a position where it does not block the light beam that has passed through the projection lens system, as shown in the figure. Thereby, the illuminance and illuminance distribution on the projection plane are measured using the same method as described above.

(Effects of the Invention) According to the present invention, as described above, the opening 11 which is an element of the illumination system
Each element is configured so that the projected image of the aperture of the light shielding plate by the projection optical system scans over the measurement Em (projection surface) By doing so, it is possible to prevent the XY stage from becoming larger and have a longer stroke, and to quickly and accurately measure the illuminance and illuminance distribution of any area on the projection surface, making it possible to perform highly accurate projection printing. It is possible to achieve this using exposure equipment.

Further, according to the present invention, a light shielding plate having an aperture whose aperture area position is variable and a pinhole plate having a plurality of pinholes of a predetermined size are used, so that the projected image of the aperture of the light shielding plate by the projection optical system is focused. By displacing the opening so as to overlap the hole, it is possible to achieve an exposure apparatus that can quickly and accurately measure the illuminance and illuminance distribution of any region on the projection plane.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts of an embodiment of the present invention, and FIG.
FIG. 3, which is a perspective view of a main part of another embodiment of the present invention with a part of the figure changed, is a pinhole plate according to another embodiment of the present invention. In the figure, 1 is the illumination system, 2 is the light shielding plate (masking plate)
, 2a is an opening, 3 is a driving means, 4 is a relay system, 5 is a reticle, 6 is a reticle stage, 7 is a reticle hunt,
8 is a projection lens system, 9 is a wafer, 10 is an XY stage,
11 is a wafer supply hand, 12 is a wafer collection hunt, 1
3 is a light detection means, 14 is a control means, and 31 is a pinhole plate.

Claims (6)

[Claims] (1) The light flux from the illumination system illuminates the projection object placed on the irradiated surface through a light-shielding plate having an aperture with a variable aperture area, and the projection object is projected onto the projection surface at a predetermined magnification by the projection optical system. In an exposure apparatus configured to project light from the illumination system, a light detection means having a light-receiving surface of a predetermined spatial size is disposed on the projection surface side of the projection optical system, and an opening of the light-shielding plate is arranged so that the light of the illumination system is An exposure apparatus comprising an illuminance measuring means that measures the illuminance and/or illuminance distribution at any position on the projection surface by the projection optical system by moving within a plane perpendicular to the axis. . (2) The exposure apparatus according to claim 1, wherein the light detection means is fixed. (3) The position of the opening of the light shielding plate is sequentially moved to specified positions by a control means, and the illuminance distribution on the projection plane is determined using the output signal from the light detection means at the specified position. 2. The exposure apparatus according to claim 1. (4) The light-receiving surface of the light-detecting means is moved so that the light flux from the illumination system does not deviate from or into substantially the same area of the light-receiving surface of the light-detecting means.
The exposure apparatus described. (5) The exposure apparatus according to claim 1, wherein the light receiving surface of the light detecting means is arranged at a position other than the projection surface on the optical axis of the projection optical system. (6) The exposure apparatus according to claim 1, wherein the light shielding plate is arranged near the irradiated surface.