JPS5814839A - Projecting exposure device - Google Patents

Abstract

PURPOSE:To improve the position deviation in image formation by sandwiching a member to be exposed which is a beltlike film having holes for driving by means of pins with light transmittable flat plates covering the exposure surface mounted to a printing frame and providing a spacing slightly larger than the thickness of the film between the flat plates. CONSTITUTION:In an imaging part, light transmittable flat plates 8, 9 consisting of, for example, glass, larger slightly than the exposure surface are disposed in such a way as to have a spacing slightly larger than the thickness of a film 1 which is a material to be exposed and to be perpendicular to the optical axis. The plates 8, 9 are supported respectively with printing frames 6, 7 and positioning pins 5 coupled to the driving holes of the film 1 are provided to the frame 7. The spacing between the plates 8 and 9 is set at about the thickness of the material to be exposed +100 microns so that the curving of the material to be exposed can be corrected small. Therefore, the deviation in the position of image formation is improved markedly, the obstacles in the design of etching patterns are eliminated and arbitrary patterns are formed with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a projection exposure apparatus, and more particularly to an apparatus suitable for exposing a film strip.

Photo-etching is often used to form an IC lead frame on a strip-shaped metal film. Conventionally, an exposure apparatus used for this means is constructed as conceptually shown in FIG. That is, (2nd edition) In this device, gold N coated with photoresist on both sides was used.
1 Film 1 is sandwiched from both sides by a square annular printing frame 2.3 to form a flat surface perpendicular to the optical axis, and the image of the front and practical photomask (not shown) is passed through the lens at point F1 and the lens at point F2. The image is formed on the film 1 and exposed. Films used in such devices usually have holes 4 formed at regular intervals in the film 10 as shown in FIG. 2, and these holes 4 are used for positioning during exposure, driving the film, etc. By the way, such holes 4 are generally formed by press punching, and there are certain limits to the dimensional accuracy of the individual holes 4 and the accuracy of the hole spacing. Therefore, the spacing between the holes 4 is adjusted to the positioning pins 51 to 5 shown in FIG.
If the spacing is larger than the respective spacing of 1.54 to 56, the film 1 will be squeezed into the free space of the baking frames 2 and 3, for example, the pin 5. When it is wrinkled between 53, 54 and 56, it may take on a shape that bulges to one side as shown in Figure 3. When a film with such poor flatness is exposed, a shift occurs in the image formation position (page 3), and the image formation patterns on the front and back sides, which should originally match, do not match. If etching is performed unless the patterns on the front and back sides match 17, the etched cross section will not be vertical, and as the pattern becomes finer, this drawback becomes fatal.

If we try to calculate the magnitude of this deviation using a model, we will get the following results: 1 In FIG. 4, point A is the center of pin 5I in FIG. 2, and point B is the center of pin 5I in FIG. be the center of

Now pin 5. and 5. Suppose that the distance between the holes 40 and 40 corresponding to these pins is larger by Lllll+, and that the film 1 curves as approximately KAPB. If the center of AB is set to 0, the overhang [7 distance Δ■ from the 0 point at the two points is expressed by the following formula.

L L+, Th,’L (△H)2+(-7)2-(---2-)i! I.

From △HΦ △L・-Ku Then, when exposing with the pattern that should be imaged at point R on AB, which is away from point 0 by r, the pattern on the R1 side is actually UQ.
, the pattern on the 1F side is imaged on Qt. FIG. 5 shows an enlarged view of that part. If the point where the perpendicular line passing through point R intersects with the straight line PB is Q, then the distance Δh between the ORs is expressed by the following equation.

r △h-△H・(1-]7) The intersection of the perpendicular lines drawn from points Q+ and Q2 to the straight line OB is R
, and Rt, the deviation of points Q+ and Q from point Q is △
QI%Δq is approximated to the deviation Δr1%Δr from point R to points R1 and R3, respectively, and its value can be approximated to Δr.

This △r is △h1 from the similarity of triangle F, 0R (F, OR) and triangle Q+ R+ R (Qt Rt R) in Figure 4.
1r 1> 1 = OF.

Therefore, for example, L=40m, ΔL=0.0 O5m, (
5th Sada) If OF, (OF2) = 100 fins, △h = 0.31
It was found that the value of Δh1Δr was 0.5.10, and the results are shown in FIG. In the figure, the horizontal axis is the position of point R “c”
) Dz The vertical axis indicates the value (μ) of OR, -OR, or 0Rt-OR. From this figure, it can be seen that when the film 1 is bent like an APB, the positional deviation of the image formation tends to increase once toward the periphery and then decrease.

That is, according to the above estimation, the maximum width reaches approximately 30 microns at the location r=lQmO. Therefore, if the line width of the pattern is 30 microns, and the image position is shifted by 30 microns, then when etching is performed, the image that should have appeared as shown in Fig. 7 (A) will instead be shown in Fig. 7 (B). It is clear that a normal etched product cannot be obtained because the cross section is as shown in FIG. Furthermore, the formation of the pin hole 4 used in the above calculation (
6th 0) The error ΔL=0.005m is a small value, and in reality it may be several tens of microns at most. This places restrictions on the positions at which fine patterns can be formed, which poses a major obstacle in pattern design.

In order to eliminate such conventional drawbacks, the present invention provides a flat plate that is arranged with a gap slightly larger than the thickness of the material to be exposed and that is large enough to cover the entire exposed surface. The exposed material is sandwiched between flat plates whose sides are translucent, and is arranged perpendicular to the optical axis to form an image forming section, and the positional deviation of the image formation is minimized. An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 8 is a sectional view showing an embodiment of the imaging section in the projection exposure apparatus of the present invention. As shown in the figure, this image forming part is arranged so that a transparent flat plate 8.9, which is slightly larger than the exposure surface, has a gap slightly larger than the thickness of the film 1 to be exposed, and is aligned with the optical axis. The flat plates 8.9 are vertically arranged and supported by printing frames 6.7, and the printing frames 7 are provided with exposure positioning pins 5. If an imaging section having such a configuration (No. 7) is used in place of a conventional vertical printing frame, it can be used in exactly the same manner as the conventional one. The flat plates 8.9 may be made of any transparent material, but glass is most preferable in terms of cost. There are no particular restrictions on how to support the light-transmitting flat plate, but it is preferable to make it removable since it is unavoidable that dust will adhere to it during repeated use.

The gap between the two flat plates 8 and 90 needs to be at least larger than the thickness of the material to be exposed 1, but the preferred size of the gap may be about 100 microns plus the thickness of the material to be exposed.

In this way, the curvature of the exposed material can be corrected to a small degree, so ΔH becomes small, and therefore Δ11 and Δr can also be made small. For example, exposure range 4 Qma+×4
Q + m, an imaging member with a gap of 170 microns between glass plates was attached to a projection exposure device with a focal pressure of #HOOgg, and a continuous pattern was formed on a 70 μ thick copper tape with resist coated on both sides. 1. After exposure, etching was performed and the image formation position deviation was measured. As a result, it was confirmed that the deviation between the front and back images was 10 μ at the maximum and within 5 μ on average.

Note that the deviation in the case not based on the present invention was 40 μ at the maximum and 20 μ on average.

The above explanation has mainly been given for the case of double-sided exposure, but it also works effectively even for single-sided exposure.

In other words, in the case of single-sided exposure, there is no deviation in the imaging position between the front and back sides, but
Inconveniences may occur if the pattern is exposed and etched out of alignment with the designed pattern. However, according to the present invention, such inconveniences can also be overcome. In this case, at least one flat plate of the imaging section may be made transparent. Further, since the other flat plate is simply used as a baking table, it may be either translucent or non-transparent.

As described in detail above, according to the present invention, the positional deviation of the image formation is greatly improved, and as a result, the obstacles in etching pattern design are eliminated, and any pattern can be photo-etched with high precision.

[Brief explanation of drawings]

Figure 1 is a conceptual configuration diagram showing a conventional projection exposure apparatus;
The figure is a plan view of the imaging section, Figure 3 (9r1) is a cross-sectional view, Figure 41!71 is an explanatory diagram of the imaging state in Figure 3, and Figure 5 is the main part of Figure 4. Enlarged view, FIG. 6 is an explanatory diagram showing an example of the image formation position deviation state in FIG. 4, FIG. 8 is a cross-sectional view showing an etched state in which the image forming position is shifted, and FIG. 8 is a cross-sectional view showing an example of the image forming part in the projection exposure apparatus of the present invention. 1... Material to be exposed (film) 5...
Exposure positioning bin 6.7...Printing frame 8.9
...Translucent flat plate patent applicant Sumitomo Metal Mining Co., Ltd. Agent 1). E゛+:H1:i Figure 6 Mi No. 8vA 256- Prisoner 7 (A) (B)

Claims (1)

[Claims] The exposure source side, which has holes for driving the film formed at regular intervals on both edges of the strip film and ilm, is held between both sides of the film by a printing frame using P pins for positioning the holes. In an exposure device in which the exposure surface is arranged perpendicular to the optical axis and serves as an imaging section, a flat plate large enough to cover the entire exposure surface is used for both printing frames, and at least the exposed side of the plate is made translucent. ,
A projection exposure apparatus in which a gap slightly larger than the thickness of the film is created between these flat plates when a material to be exposed is held between pins.