JPH04146441A - Film exposing device - Google Patents

Abstract

PURPOSE:To offer a film exposing device which can perform an exposure in an appropriate focal state even after starting an exposing operation by monitoring a projected image by an image sensor by every one frame of a film to be projected and exposed, and moving a reticle and a projecting lens or one of them and focusing. CONSTITUTION:The projected image projected on a film F is made incident on the detecting part 40 of a stage 30 through a hole provided as a mark on a film side. And the image which is made incident on an objective lens 41 is refracted by a half mirror 44. And refracted light is made incident on the image sensor 45. At this time, the image sensor 45 works as a monitoring system, the projected image on the film F is monitored. The image sensor 45 is arranged in such a way that it is focused with the aerial image of the mark for focusing which is formed in the hole as the mark on the film side. And the projected image is monitored by the image sensor 45 by every one frame of the film F, and focusing control is executed by moving the reticle 10 and the projecting lens 20 in an optical axis direction.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention relates to a film exposure apparatus suitable for manufacturing film circuit boards. [0002]

[Conventional technology]

Photolithography technology is known as a technology for performing microfabrication on the surface of an object. In addition to semiconductor integrated circuits, this technology has recently been applied to the production of film circuit boards used to mount electronic components. [0003] Such an exposure apparatus includes an irradiation section having a light source, a reticle on which a circuit pattern to be exposed is formed by being irradiated with synchrotron radiation from the irradiation section, and a projection lens that projects an image set on the reticle. and a stage that sets the film at the projection position to form the exposure position. When performing projection exposure, the work of focusing the projected image is performed before starting the projection exposure. [0004] This focusing is performed, for example, by a method as described in Japanese Patent Application Laid-Open No. 1-191493. That is, this is performed by moving the projection lens position adjustment mechanism and the reticle position adjustment mechanism in the optical axis direction while monitoring images of patterns, alignment marks, etc. projected onto the exposure surface using a monitor system. [0005] However, (when the projection lens position adjustment mechanism or reticle position adjustment mechanism is operated in order to perform focusing and the projection lens or reticle is displaced in the optical axis direction, the magnification of the projected image is thereby displaced. [0006] In order to solve such problems, patent application No. 2-813
As shown in No. 37, a method of focusing while maintaining the positional relationship between a projection lens, a reticle, and a projection surface of a film based on a set magnification has been proposed. [0007]

[Problem to be solved by the invention]

However, in conventional apparatuses, focus is adjusted while monitoring with a monitor system only before starting actual exposure. i.e. - once the rotational light operation is started,
The focal point of the projection image is projected at the reticle position and projection lens position set before the start. That is, if the exposure apparatus vibrates or changes in temperature for some reason, the positions of the reticle and projection lens will be deviated, and naturally the positional relationship between them will deviate from the set value. This results in an out-of-focus exposure, and if you continue to operate the device without noticing this condition,
You end up wasting a lot of film. [0008] On the other hand, the above-mentioned problem can be solved by periodically performing the focusing work that was performed before the start of the exposure work even after the start of the exposure work. Performing the work regularly is very complicated. [0009] An object of the present invention is to provide a film exposure apparatus that can perform exposure in an optimal focus state even after starting exposure work. [0010]

[Means to solve the problem]

In order to solve the above object, the film exposure apparatus of the present invention is a film exposure apparatus that sequentially exposes a circuit pattern along the length of a strip-shaped film, and includes an irradiation section and an irradiation section. A reticle is placed at a position where it is irradiated with light and has a focusing mark separate from the circuit pattern to be projected, a projection lens projects an image of the reticle, and the reticle is displaced in the optical axis direction to adjust the position. The reticle position adjustment mechanism adjusts the reticle position, the projection lens position adjustment mechanism adjusts the position by displacing the projection lens in the optical axis direction, and the strip-shaped film projects an aerial image of the focusing mark for each frame. The image sensor has a hole or a transparent part, and is arranged to focus at a position a certain distance away from the hole or the transparent part, and a focusing mark input to the image sensor. It has a means for detecting variations in the amount of light of the projected image, and a signal from the detecting means drives a reticle position adjustment mechanism and/or a projection lens position adjustment mechanism to detect variations in the amount of light for each frame of the strip-shaped film. It consists of a system controller that can automatically focus. [0011]

[Effect]

With this configuration, when one frame of the film to be exposed is transported and set at the exposure position, variations in the amount of light on the film hole or transparent part of the focusing mark provided on the reticle are detected. can do. In other words, this variation in the amount of light indicates whether or not the focus is out of focus, so this detection signal allows the reticle and projection lens to be displaced in the optical axis direction to automatically adjust the focus for each frame of the film. . [0012]

【Example】

The present invention will be explained in detail below. Figures 1, 2, and 3 are
FIG. 1 is an explanatory diagram of a film exposure apparatus according to an embodiment of the present invention. [0013] FIG. 1 shows an irradiation unit that includes a light source 11, a mirror that reflects the emitted light from the light source 11, and an integrator lens. As the light source 11, one that efficiently emits light to which the resist is sensitive, such as an ultra-high pressure mercury lamp, is used. [0014] Reference numeral 10 denotes a reticle, which is placed at a position where light from the irradiation section 1 is irradiated. This reticle 10 includes a circuit pattern to be projected and transferred onto the film F, as well as focusing marks corresponding to film-side focusing marks to be described later. [0015] This focusing mark is composed of, for example, a rectangular opaque part and a cross-shaped transparent part. The film-side mark is composed of, for example, a round hole or a transparent portion for each frame of the film F. [0016] Reference numeral 12 denotes a reticle position adjustment mechanism, which is composed of, for example, a servo motor. A projection lens 20 projects an image of the irradiated reticle 10. This projection lens 2
0 has a resolution of, for example, an exposure line width of 110 At. 21 is a projection lens position adjustment mechanism of this projection lens 20. The reticle position adjustment mechanism 12 and the projection lens position adjustment mechanism 21 are driven by a system controller 50, which will be described later. Then, the reticle 10 and the projection lens 20 are displaced in the optical axis direction Y. Reference numeral 30 denotes a stage, and as shown in FIG. 2, one frame of the film F to be exposed is fed stepwise to the exposure position and then stopped. This stopping must be done at an accurate exposure position, and this method is shown in, for example, Japanese Patent Laid-Open No. 2-81336. A vacuum suction hole 31 for vacuum suctioning the film F only during exposure is provided. [0017] 40 is a detection unit, which includes an objective lens 41 and a condensing lens 42
, a photoreceiver 43 consisting of a photodiode, etc., and a half mirror.
44, and an image sensor 45 such as a CCD that detects light refracted by the half mirror 44. An aerial image on the film-side mark on the film F is incident on the image sensor 45 [0018]The image sensor 45 is positioned a certain distance apart from the film-side mark. That is, if the projected image input to the image sensor 45 is detected in consideration of this distance, the projected image on the film F can be detected. Furthermore, even if the image sensor 45 focuses on a position a little distant from the film side mark, the projected image on the film F can be detected by converting the distance. [0019] In addition, such control is performed before printing the circuit pattern.If the wavelength input to the image sensor 45 is different from the wavelength used to print the circuit pattern, it is necessary to perform the control from the mark on the film side. It is preferable that the image sensor 45 be in focus at a slightly distant position. [00201 60 is a film feeding mechanism, which steps one frame of the film F to the position where the image is projected by the projection lens 20. 61 is a feed roller, 63 is a press roller, 64 is a sprocket roller, 65 is a press roller, 66, 67 is an auxiliary roller, 68 is a supply roller, and 69 is a take-up roller. [0021] Next, the focusing operation in the film exposure apparatus of the present invention will be specifically explained. The projected image projected onto the film F passes through a hole provided as a mark on the film side and is sent to the detection unit 40 of the stage 30.
is incident on the The image incident on the objective lens 41 is refracted by a half mirror 44. The refracted light is then incident on the image sensor 45. At this time, the image sensor 45 functions as a monitor system and monitors the projected image on the film F. Here, the image sensor 45 is arranged so as to focus on an aerial image of a focusing mark formed in a hole as a mark on the film side. [0022] Since the focusing mark in this case is a cross as described above, this projected image input to the image sensor 45 appears on the monitor system as shown in FIG. 3(a). The image sensor 45 is composed of, for example, an array of CCDs, and has, for example, a predetermined detection line 60 set therein. Therefore, CCDs are naturally arranged along the detection line 60 as well. A portion 61 where the cross that is the focusing mark and the detection line 60 overlap
, shows an image projected on the film-side mark on the stage 30 through which the radiation light from the irradiation section 1 passes. [0023] FIG. 3(b) is a diagram showing the amount of light at the image sensor 45 at a portion 61. That is, in this portion 61, the amount of received light is detected by each CCD placed on the detection line 60. In the figure, the vertical direction indicates the amount of received light, and the horizontal direction indicates the detection line 60. for example,
A solid line 62 in the figure shows a rectangular waveform, and indicates that the amount of light received by the CCD in the portion 61 is high and has no variation. That is, it shows a state in focus (in-focus state). [0024] On the other hand, the dotted line 63 shows a chevron shape with high and low light intensity points within the portion 61, indicating a state where the focus is not very high. Hereinafter, the focusing operation will be specifically explained based on the dotted line 63. Jumonji part 6
Of the amounts of light received by each CCD in No. 1, No. 66 indicates the peak value. A point 64 indicates a light amount of 80% of the light amount of this peak value 66. Similarly, the 60% point is indicated by 65. This 80% point 64 and -60% point 65
is received by one of the CCDs on the detection line 60, and it can be said that the closer to zero the distance difference between the positions in the horizontal axis direction, the less variation in the amount of light and the more focused it is. [0025] On the other hand, if this difference is large, it is determined that the projected image on the film is out of focus. In this way, the focus state can be detected by detecting the amount of light at a point on the detection line 60 on the image sensor 45. A signal detecting this state is sent to the system controller 50. The system controller 50 sends signals to the reticle moving mechanism 12 and the projection lens moving mechanism 21 based on a predetermined reference value that allows it to be determined that the focus is on.
send to Then, the reticle 10 and the projection lens 20 are moved in the optical axis direction to perform focusing. In this way, in the exposure apparatus, the image sensor 45 monitors the projected image of each frame of the film F, and automatically focuses the reticle 10 and the projection lens 20 by moving them in the optical axis direction. can be controlled. Also, focusing control does not necessarily need to be performed for each frame; for example, 10 frames may be 30 frames.
A similar effect can be obtained even with a configuration in which detection control is performed every few frames. [0026]Although the points on the detection line 60 are set at 80% and 20% of the peak light amount value, they are not limited to these points. Further, although a CCD is employed as the image sensor 45 in this case, a vacuum tube type image sensor may also be used. [0027]Also, in the embodiment of the present invention, a projection image is detected for focusing and a film side mark (hole) is used on the film F, but the film side mark is not limited to a hole. A light-transmitting portion may be provided. [0028]

【Effect of the invention】

As explained above, according to the film exposure apparatus of the present invention, for each frame of the film to be exposed by projection,
The projected image is monitored by an image sensor, and
Focusing can be controlled automatically by moving the chicle and/or the projection lens. Therefore, even if the apparatus vibrates for some reason even after the exposure operation has started, focusing control on the projected image can be performed in response to these vibrations. Therefore, exposure work can always be performed in good condition.

[Brief explanation of the drawing]

[Figure 1] FIG. 1 is an explanatory diagram of a film exposure apparatus of the present invention.

[Figure 2] FIG. 3 is an explanatory diagram regarding detection of a projected image on a projection plane.

FIGS. 3(a) and 3(b) are diagrams illustrating a focusing operation.

[Explanation of symbols]

1 Irradiation section 10 Reticle 12 Reticle position adjustment mechanism 20 Projection lens 21 Projection lens position adjustment mechanism 40 Detection part F Film

【Document name】

[Figure 1] drawing

[Figure 2]

[Figure 3] (a)

Claims (1)

[Claims] 1. A film exposure device that sequentially exposes a circuit pattern along the length of a strip-shaped film, the device having an irradiation section and a position where light from the irradiation section is irradiated; A reticle that has a focusing mark separate from the circuit pattern to be imaged, a projection lens that projects an image of the reticle, a reticle position adjustment mechanism that adjusts the position by displacing the reticle in the optical axis direction, and a reticle position adjustment mechanism that adjusts the position by displacing the reticle in the optical axis direction. The projection lens position adjustment mechanism adjusts the position by displacing it in the axial direction, and the strip-shaped film has a hole or transparent part on which an aerial image of the focusing mark is projected for each frame. an image sensor arranged to focus at a position a certain distance away from the hole or the transparent part;
It has means for detecting variations in the amount of light in the projected image of the focusing mark input to the image sensor, and the reticle position adjustment mechanism and/or the projection lens position adjustment mechanism is driven by the signal from the detection means. and a system controller capable of automatically focusing each frame of a strip-shaped film.