JPH0697034A - Projection aligner - Google Patents

Abstract

PURPOSE:To surely and accurately recognize a mark by solving a technical problem that the mark illumination light to a substrate is applied directly and vertically to the substrate. CONSTITUTION:The mark illumination light is directed to the mark surface of a substrate (K) on a stage 21 with reflection of a light passing mirror 7, and the reflected light of the mark is transmitted through a projecting lens 20 from the light passing mirror 7, thereby forming an image on a mask (M) to project the mark illumination light onto the mark of the substrate with an adequate illumination intensity, so that even the mark of low reflectance may be surely recognized and the shape of the mark of the substrate (K) may be accurately recognized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus for printing graphic patterns of electronic circuits on a semiconductor wafer.

[0002]

2. Description of the Related Art As shown in FIG.
Light source body 15 composed of an ultra-high pressure mercury lamp and an elliptical mirror
And a combination of the first reflection mirror 16 for controlling the irradiation spectrum by guiding the light from the light source body 15 in a fixed direction and for controlling the irradiation spectrum, the combination of the fly-eye lens 17 and the second reflection mirror 18, and the condenser lens. 19 and a projection lens 20 for forming an image light beam passing through the mask M at an exposure position
And a stage 21 for mounting the substrate K which is an exposed object.

In this projection optical system 14, a mask M for drawing a graphic pattern to be exposed is replaced by a condenser lens 19
And the projection lens 20, and the graphic pattern of the mask M is exposed on the exposure surface, which is the upper surface of the substrate K assembled on the stage 21, before the exposure processing of the substrate K. Then, it is necessary to achieve the alignment between the mask M and the substrate K along a plane orthogonal to the optical axis of the projection optical system 14.

The alignment between the substrate K and the mask M is
Marks previously formed on the substrate K and the mask M are
It is achieved by adjusting the displacement of at least one of the substrate K and the mask M while optically observing.

As shown in FIG. 3, the conventional mark aligning means is arranged between the condenser lens 19 and the mask M.
Light source 22 for mark illumination, condenser lens 23, CCD 2
A camera 25 using a three-dimensional sensor, and a constituent of a half mirror are arranged, and the illumination light from the mark illuminating light source 22 is supplied to the mask M and the projection lens 20 by the two half mirrors and the condenser lens 23. Through the projection lens 20 and the mask M, the camera 25 receives the reflected light from the substrate K through the projection lens 20 and the camera 25, and the camera 25 performs the alignment while observing.

As shown in FIG. 4, another conventional mark aligning means collects the illumination light from the mark illuminating light source 22 on the mark portion of the substrate K assembled on the stage 21. It collects at 23 and irradiates from diagonally above,
The reflected light of the irradiation light on the surface of the substrate K passes through the projection lens 20 and the mask M, and is received by a combination of the objective lens 24 and the camera 25 arranged between the condenser lens 19 and the mask M, and this camera 25 Positioning is performed while observing.

[0007]

However, among the above-mentioned conventional techniques, the means shown in FIG. 3 is arranged such that the projection lens 20 is moved until the camera 25 receives the mark illuminating light from the mark illuminating light source 22. Since the light passes through twice and is dimmed, there is a problem that the mark itself may not be recognized and the alignment operation may not be performed with the mark having a poor reflectance.

The means shown in FIG. 4 does not have the problem that the quantity of mark illumination light in the means shown in FIG. 3 is insufficient, but since the mark illumination light is emitted obliquely, the mark is not emitted. If it is thick, the shape of the mark cannot be correctly recognized, and there is a problem that misalignment of the mark shape may cause misalignment.

Therefore, the present invention was devised in order to solve the above-mentioned problems in the prior art, and it is a technique of irradiating a mark illuminating light to a substrate exposure surface directly and perpendicularly to the exposure surface. The objective is to ensure that the mark can be recognized reliably and accurately.

[0010]

The means of the present invention for solving the above technical problems has a light source for illuminating marks, which is arranged laterally of the stage of the projection optical system, and the projection of the projection optical system. It is placed between the lens and the stage and reflects the illumination light from the light source perpendicularly to the exposure surface of the substrate mounted on the stage, and passes the light reflected from the exposure surface of this substrate to the projection lens. Having a mirror,
And a combination of an objective lens and a camera for observing the reflected light passing through the projection lens through a mask attached to the projection optical system.

The light-transmitting mirror is used as a part of the total reflection mirror,
It is preferable to form a through hole that allows the reflected light from the exposed surface of the substrate to pass therethrough, or to use a half mirror alone.

[0012]

The mark illuminating light from the light source for illuminating the mark does not pass through the projection lens of the projection optical system, but is directly irradiated onto the exposed surface of the substrate through the light passing mirror, and therefore passes through the projection lens. The mark on the exposed surface of the substrate is irradiated with no illuminance attenuation.

Therefore, the mark illuminating light can be applied to the mark on the exposure surface of the substrate with sufficient illuminance, whereby the reflected light from this exposure surface of the substrate passes through the projection lens and the mask, and the objective Even when some illuminance is attenuated by passing through the projection lens when it is incident on the combination of lens and camera, the illuminance should be within the range sufficient to achieve the mark alignment. Therefore, even if the mark has a low reflectance, the mark can be surely recognized.

Further, the irradiation direction of the mark illuminating light from the light source is changed by the light passing mirror so that it becomes epi-illumination which is radiated almost perpendicularly to the mark surface which is the substrate exposure surface. Is set.

Therefore, the mark illumination light is always radiated perpendicularly to the mark surface of the substrate, whereby the mark shape can be accurately recognized regardless of the size of the mark. it can.

When the light passing mirror is composed of a half mirror, the half mirror can be used as it is as the light passing mirror, and the structure is simplified accordingly, whereas the light passing mirror is a total reflection mirror. If a light-transmitting mirror is configured by forming a through hole in a part of it, the configuration of the light-transmitting mirror becomes complicated, but the illuminance of the reflected light from the mark on the substrate when passing through the light-transmitting mirror is There is no attenuation at all, and there is no positional deviation due to refraction when passing through the light passing mirror, whereby more reliable and accurate mark alignment processing can be achieved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic overall configuration example of a mark alignment mechanism 1 according to the present invention. A light source 2 for emitting mark illumination light and a condenser lens 6 for concentrating the mark illumination light from the light source 2 are shown. And a light passing mirror 7 that reflects the mark illumination light to irradiate the mark on the exposed surface of the substrate K and also allows the reflected light from the mark on the substrate K to pass toward the projection lens 20 of the projection optical system 14, It is composed of a camera 13 which receives the reflected light from the mark on the substrate K that has passed through the lens 20 and the mask M via the objective lens 12 and observes the positional relationship between the mark on the substrate K and the mark on the mask M. ing.

The focus of the condenser lens 6 is set so that the mark illumination light reflected by the light passing mirror 7 is condensed on the exposure surface of the substrate K.

The light passing mirror 7 is arranged immediately above the mark on the substrate K mounted on the stage 21, and its reflection surface is 4 with respect to the optical axis of the mark illumination light from the light source 2.
By inclining by 5 °, the mark illumination light condensed by the condenser lens 6 is irradiated perpendicularly to the mark surface which is a part of the exposure surface of the substrate K.

In the illustrated embodiment, this light passing mirror 7
Is a total reflection mirror, and penetrates in a vertical direction at a position where the optical axis portion of the reflected light of the mark illumination light applied to the substrate K is located, that is, a position immediately above the mark on the substrate K. The structure is such that the through hole 8 is opened therethrough.

The objective lens 12 and the camera 1 for receiving the reflected light transmitted from the mark portion of the mask M from the projection lens 20.
The combination with 3 is the conventional objective lens 24 shown in FIG.
As with the combination of the camera and the camera 25, as shown in FIG. 3, the objective lens 12 is formed by combining a reflecting mirror and a condenser lens.
The CCD 13 constitutes a part, and the camera 13 is constituted by a CCD two-dimensional sensor.

FIG. 2 shows a detailed structural example of a combination of the light source 2, the condenser lens 6 and the light transmission mirror 7 in the embodiment shown in FIG. The light source 2 is constructed by attaching a filter 4 for selecting a specific wavelength and a diaphragm 5 for regulating the irradiation area of the mark illumination light by a head frame piece 10 assembled and fixed to the tip of the light guide 3 at the tip. The tip of the light source 2 is inserted and assembled with the optical axis of the light source 2 positioned on the central axis of the light source 2, and the condenser lens 6 is assembled and fixed in the tip of the frame 9. The light-transmitting mirror 7 is attached to a mounting frame piece 11 that is externally fitted to the tip, with its reflecting surface tilted at an angle of 45 ° with respect to the optical axis of the mark illumination light.

In the case of the embodiment shown in FIG. 2, since the light source 2, the condenser lens 6 and the light passing mirror 7 are integrally combined, the handling thereof is easy and simple.

For the alignment of the substrate K and the mask M, the image of the mark of the substrate K formed on the surface of the mask M through the projection lens 20 and the alignment mark of the mask M are taken by the camera. The operation is carried out in the same manner as in the prior art, though the operation is performed by capturing the image in the same visual field at 13 and adjusting the movement of the mask M or the substrate K.

[0025]

EFFECTS OF THE INVENTION Since the present invention has the above-mentioned structure, it has the following effects. Since the illumination light that illuminates the mark on the substrate is directly applied to the mark on the substrate without passing through the projection lens of the projection optical system, it is possible to illuminate the mark with sufficient illuminance, and for example, a mark with low reflectance. Since it is possible to clearly recognize even if there is, it is possible to eliminate the inconvenience of being unable to perform alignment due to unrecognizable marks.

Since the mark illumination light is emitted perpendicularly to the mark surface of the substrate, the mark shape can be correctly recognized even if the mark thickness is large, and therefore the alignment work can be performed with high accuracy. Can be achieved.

A combination of a light source, a condenser lens, and a light passing mirror is arranged on the side of the stage of the projection optical system, and the combination of the objective lens and the camera may be the same as the conventional one. Therefore, it is easy to assemble the projection optical system.

[Brief description of drawings]

FIG. 1 is a layout configuration diagram showing an embodiment of a basic configuration of the present invention.

FIG. 2 is a vertical cross-sectional view showing a specific configuration example on the light source side of the embodiment shown in FIG.

FIG. 3 is an overall configuration diagram showing a conventional example of a mark alignment mechanism attached to a projection optical system.

FIG. 4 is a configuration diagram showing another conventional example of a mark alignment mechanism.

[Explanation of symbols]

1; Mark alignment mechanism 2; Light source 3; Light guide 4; Filter 5; Aperture 6; Condensing lens 7; Light passing mirror 8; Through hole 9; Frame cylinder 10; Head frame piece 11; Mounting frame piece 12; Objective Lens 13; Camera 14; Projection optical system 15; Light source 16; First reflection mirror 17; Fly-eye lens 18; Second reflection mirror 19; Condenser lens 20; Projection lens 21; Stage 22; Mark illumination light source 23; Optical lens 24; Objective lens 25; Camera K; Substrate M; Mask

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03F 9/00 H 9122-2H

Claims (3)

[Claims] 1. A light source (2) for illuminating a mark, which is arranged on a side of a stage (21) of a projection optical system (14), and the projection optical system.
It is arranged between the projection lens (20) of (14) and the stage (21), and the illumination light from the light source (2) is applied to the exposure surface of the substrate (K) mounted on the stage (21). The projection lens reflects light reflected from the exposed surface of the substrate (K) while reflecting vertically.
A light-passing mirror (7) for passing through (20), and the projection lens
A mark alignment mechanism comprising a combination of an objective lens (12) and a camera (13) for observing the reflected light passing through (20) through a mask (M) attached to the projection optical system (14). A projection exposure machine equipped with (1). 2. A light passing mirror (7), a part of the total reflection mirror for transmitting light reflected from the exposed surface of the substrate (K).
The projection exposure apparatus according to claim 1, wherein (8) is opened and configured. 3. The projection exposure apparatus according to claim 1, wherein the light passing mirror (7) is a half mirror.