KR20090031977A - Maskless exposure apparatus - Google Patents

Abstract

A maskless exposure apparatus is provided to control the location of the projection lens by the movement of the wedge glass and to expose the pattern of the uniform width in the surface of the work piece. The side of the first wedge glass(717) is perpendicularly arranged about the optical axis of the second projection lens(67). The side of the second wedge glass(727) is arranged in the incidence side or the output side of the second projection lens. In the substrate thickness direction of each wedge glasses, one surface is inclined as the angle theta to the other surface. If the imaging location of the optical axial of the second projection lens crosses each other from the surface of the exposure substrate, the second wedge glass is moved as the angle theta to position the image formation face of the second projection lens at the surface of the exposure substrate.

Description

Maskless exposure device {MASKLESS EXPOSURE APPARATUS}

The present invention relates to a maskless exposure apparatus that exposes a pattern to an exposure substrate without using a mask.

In order to form a wiring pattern on a printed board, a pattern is conventionally formed in a mask, and this mask pattern is projected and exposed using a mask exposure machine, or the pattern is exposed to the exposed substrate by close or proximity exposure. It was exposing. In recent years, a technique of directly exposing to an exposure substrate without using a mask has been developed, and industrial utilization has begun (see the following patent document). And with such a maskless exposure apparatus, the printed circuit board of 20 micrometers of pattern widths can be produced, for example.

[Patent Document] Japanese Unexamined Patent Application Publication No. 2004-39871

In order to further improve the mounting density of electronic components and the like, it is required to reduce the pattern width to 10 μm or less. However, when exposing a pattern of 10 µm or less, the width of the depth of focus is narrow. Therefore, if there is a bent state or thickness irregularity in the exposure substrate, it becomes difficult to make the width of the pattern uniform.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a maskless exposure apparatus capable of exposing a pattern having a uniform width to the surface of a workpiece even when the workpiece is bent or has thickness irregularities.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention hold | maintains the said exposure light source which outputs exposure illumination light, a 2D space modulator, a 1st projection lens, a micro lens array, a 2nd projection lens, and an exposure substrate, In a maskless exposure apparatus comprising a stage moving in a direction orthogonal to an optical axis of a projection lens, a first wedge glass and a second wedge, in which one surface in the plate thickness direction is a surface inclined at an angle θ with respect to the other surface in the plate thickness direction. Two wedge glass of glass and a moving means for moving at least one of the said wedge glass are provided, The said other surface of the said 1st wedge glass is arrange | positioned perpendicularly to the optical axis of a said 2nd projection lens, The said 1st 2 the one side of the wedge glass is combined so that the distance from the one side of the first wedge glass becomes a predetermined value, and the mouth of the second projection lens When it is arrange | positioned at the side or an emission side, and the imaging position of the said optical-axis direction of the said 2nd projection lens is shift | deviated from the surface of the said exposure board | substrate, the said distance means makes any one of the said wedge glass constant, The imaging plane of the second projection lens is positioned on the surface of the exposure substrate by moving in the angle θ direction.

Even if the workpiece is bent or the thickness is uneven, a pattern having a uniform width can be exposed on the surface of the workpiece.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail with reference to drawings.

Example 1

1 is a configuration diagram of a first maskless exposure apparatus according to the present invention.

The exposure illumination systems 11-17 which consist of seven optical axes are substantially the same structure. Incidentally, in order to avoid the complexity of the figure, the numbers and signal lines (dotted lines) are displayed only in the parts of the seven optical axes that are easy to display, but the numbers and signal lines are the same on all the optical axes. Hereinafter, the exposure illumination system 17 among the exposure illumination systems 11-17 is demonstrated.

The exposure illumination light emitted from the exposure illumination system 17 is irradiated to the two-dimensional space modulator 37 located above by the return mirror 27. Here, a digital mirror device (hereinafter referred to as "DMD") 37 is used as the two-dimensional spatial modulator.

In the DMD 37, a plurality of movable micro mirrors are arranged in a matrix in the xy plane. When the ON / OFF signal is sent from the control apparatus 9 to each micromirror, the micromirror which received the ON signal is inclined at an angle and reflects the incident exposure illumination light to enter the first projection lens 47. The exposure illumination light reflected by the micromirror in the OFF state does not enter the first projection lens 47 and does not contribute to the exposure. The exposure illumination light that has passed through the projection lens 47 is incident on the micro lens array 57. Microlenses are disposed at positions of the microlens arrays 57 where the enlarged image (or reduced image) of the micromirror of the DMD 37 is formed.

Each micro lens disposed in the micro lens array 57 is a convex lens having a focal length of fм, and the exposure illumination light (exposure illumination light from the micromirror in the ON state) that is incident approximately perpendicular to each micro lens is generally from each micro lens. A micro spot is formed at the position of fм.

A pinhole array having an opening diameter equal to the spot diameter may be arranged at this spot formation position. By arranging the pinhole array, it is possible to shield extra (unnecessary) light.

The spot pattern generated at the position fmi below the microlens is incident on the second projection lens 67, and the exposure illumination light exiting the second projection lens 67 is a wedge composed of wedge glass 717 and wedge glass 727. It penetrates through glass unit GU7, and the spot pattern arrangement | positioning image of magnification (mu) is formed on the exposure board | substrate 8.

Next, the wedge glass unit GU7 is demonstrated.

FIG. 2 is a perspective view of an essential part of the wedge glass unit GU7, and FIG. 3 is a view as viewed in K of FIG. 2.

The wedge glass 717 is a surface in which one surface 717b in the plate thickness direction is inclined at an angle θ with respect to the other surface 717a in the plate thickness direction. In addition, the wedge glass 727 is a surface in which one surface 727b in the plate thickness direction is inclined at an angle θ with respect to the other surface 727a in the plate thickness direction. The surface 717a is disposed perpendicular to the optical axis of the second projection lens 67. On the other hand, the wedge glass 727 is arrange | positioned and arrange | positioned so that surface 727b may become distance (interval) (delta) with respect to the surface 717b. Incidentally, in this embodiment, the sizes of the wedge glass 727 and the wedge glass 717 are the same in the xy direction, respectively, and as shown in FIG. The distance from both surfaces 717a of "the reference position of wedge glass" to the surface 727a of t in the case is t. Hereinafter, distance t is called "total thickness" of wedge glass. The total thickness t at the reference position is set to 4-7 mm. The distance δ is a constant value between 0.01 and 0.3 mm. And although the minimum value of distance (delta) may be made smaller than 0.1 mm, it is practical to consider the minimum value of distance (delta) to be about 0.05 mm, considering the ease of manufacture of the moving mechanism mentioned later. The maximum value of the distance δ is 0.3 mm because the aberration increases when the distance δ exceeds 0.3 mm.

A moving mechanism, not shown, follows the wedge glass 727 (or any of the wedge glass 717) along the face 727b (strictly speaking, along the direction of the vector perpendicular to the normal of the slope and parallel to the slope). ) The wedge glass 727 is moved. This moving mechanism is controlled by the control circuit 9.

Now, when the wedge glass 727 is moved + Δy in the y direction along the inclined surface, the total thickness change Δt of the glass in the direction parallel to the optical axis of the projection lens 2 is given by Equation 1 below.

Δt = -Δy tan θ... (Equation 1)

Here, the refractive index of the wedge glass 717,727 is n. Then, since the total thickness changes Δt, the change amount Δz of the focal position of the second projection lens 727 is expressed by the following expression (2, and the upper side is positive).

Δz = −Δt · (n−1) / n

    = Δy · tanθ · (n−1) / n... (Equation 2)

That is, the wedge glass unit GU7 is a focusing device.

Therefore, when the height h (x, y) of the resist surface on the exposure substrate 8 or the surface on which the resist is loaded is measured in advance, the spot image can be positioned on the resist surface as follows. That is, the data of height h (x, y) is put in the control circuit 9, and the wedge glass 717, 727 is arrange | positioned at a reference position, and the imaging surface of the 2nd projection lens 67 is taken. ) Corresponds to the design surface height of the exposure substrate 8. And the average height hm of the area | region exposed by the projection lens is calculated | required according to the data memorize | stored in the control circuit 9, and the wedge glass 72 is made so that (DELTA) z in Formula (2) may become the height of hm ((DELTA) z = hm). ? Y is moved and exposed. In this way, exposure with excellent precision can be performed.

By the way, in the conventional maskless exposure apparatus, the surface of an exposure substrate is assumed to be flat, and the 2nd projection lens is made so that the imaging surface of 2nd projection lenses 61-67 may match with the surface of the exposure substrate which assumed. (61 to 67) were positioned in the z direction.

However, for example, in the case of a multilayer printed circuit board, not only the plate thickness differs depending on the place, but also the exposure surface is hardly flat due to the warped state or unevenness of the substrate surface due to the stacking of the substrates. Therefore, for example, it was difficult to make the width of a pattern uniform.

Next, a description will be given of a maskless exposure apparatus capable of performing exposure with excellent accuracy even when there are irregularities on the surface of the exposure substrate or when there is a curved state.

And wedge glass unit GU7 may be arrange | positioned at the entrance side of the 2nd projection lens 67 (namely, between the micro lens array 57 and the 2nd projection lens 67).

Example 2

FIG. 4 is a configuration diagram of a maskless exposure apparatus according to the present invention, and the same reference numerals as in FIG. 5 is a block diagram of a height detector.

A plurality of height detectors 600 are arranged in the x direction on one side of the second projection lens group (the second projection lens 61 to 67 in the y direction (right in front of the illustrated case)) disposed above the stage 80. An array of multi height detectors 600U is provided, arranged in. Each height detector 600 detects the surface of the resist surface of the exposure substrate 8 or the surface height of the exposure substrate itself under the resist.

Next, the structure of the height detector 600 is demonstrated.

As shown in FIG. 5, the height detector 600 includes a light emitter 601, a lens 602, a lens 603, and a position sensor 604. The light emitter 601 is a semiconductor laser LD that outputs red light that does not expose the light emitting diode (LED) or the resist. The lens 602 condenses the light emitted from the light emitter 601 on the surface of the exposure substrate 8. The lens 603 collects the light reflected from the substrate surface and forms an image on the position sensor 604 as a reflecting portion of the substrate.

Since it is the structure as mentioned above, the height of the exposure board | substrate 8 set to the processing program (average height obtained by actually measuring the height of several places of the exposure board 8 or design height. Hereinafter, it is called "setting height". ), The imaging position on the position sensor changes depending on the magnitude of the deviation from the set height. Therefore, the height of the actual exposure substrate 8 can be detected by reading this amount of change.

Next, the operation of the embodiment of the present invention will be described.

4, the stage 80 on which the exposure substrate 8 is mounted is moved in the y direction at a constant speed v in accordance with the sensitivity of the photosensitive material. Each height detector 600 detects the surface height of the exposure board | substrate 8 every fixed time. The detected surface height is stored in the storage unit of the control circuit 9 together with the positional information (measured xy coordinate value of the location) of the exposure substrate 8. The location where the height is detected reaches the exposure position 87 (a rectangle that is similar to the DMD 37) when the time determined by the speed v elapses. The control circuit 9 calls the surface height of the exposure substrate 8 which reached the exposure position 87 from a memory | storage part, moves the wedge glass 727 to ay direction according to this information, and 2nd projection lens The imaging surface of 67 is matched with the surface of the exposure substrate 8.

FIG. 6: is sectional drawing of the exposure board | substrate 8, and is a figure which shows typically the surface vicinity in the case where the exposure board | substrate 8 is cross-sectioned in the x direction.

In the same figure, the surface of the exposure substrate 8 is shown by the solid line. In addition, the surface 700 (Σex0) is a set height. As shown in the same figure, the height in the exposure position 87 changes with each place. Since the detector 600 is arrange | positioned at the both ends of each exposure position here, the imaging surface of the 2nd projection lens shown by the dotted line is positioned by the average value of the height of both ends of each exposure position. And by narrowing the arrangement | positioning space of the detector 600, the nonuniformity of the difference of the surface of the actual exposure substrate 8 and the imaging surface of a projection lens can be made small.

In addition, although the cross section of the x direction was demonstrated here, it can be said that it is the same also in the y direction. Therefore, for example, if the length in the y direction of the exposure position 87 is y1 and the length in the x direction is x1, the height of the image plane of the second projection lens is measured within the area y1 × x1. It is practical to try to average. The same applies to the other exposure positions 81 to 86.

As described above, in the present embodiment, since the measurement of the surface height of the exposure substrate and the position adjustment in the height direction of the imaging surface are performed in parallel with the exposure, the imaging surface is approximately the surface of the exposure substrate over the entire surface of the exposure substrate. Can fit in. As a result, the pattern width becomes uniform.

Next, a method of further improving the height detection accuracy of the exposure substrate surface by the detector 600 will be described.

The Brewster whose measurement light output from the light-emitting body 607 described in FIG. 5 is P-polarized light and the incident angle of the chief ray B11 is determined by the refractive index of the photosensitive layer disposed on the surface of the exposure substrate 8 Incident as the Brester angle θв. In this way, as shown in Fig. 7, all incident light passes through the photosensitive layer 81 (i.e., is not reflected on the surface of the photosensitive layer) and reaches the substrate surface of the base portion. Further, the light reflected from the substrate surface of the base portion and returned upward is not reflected at the surface of the photosensitive layer while being substantially P polarized, and returns upward as it is, and exits from the photosensitive layer as the detection light D11 to position sensor 604. ). That is, the noise light D11n indicated by the dotted line in the figure reflected by the surface of the photosensitive layer, which becomes noise at the time of detection, becomes zero. Incident light incident on the position sensor 604 is hardly attenuated. Therefore, detection (measurement) with excellent precision can be performed.

In addition, since the result measured by the detector 600U is stored in the control circuit 9, even if there is a bent state, for example, exceeding the depth of focus of the second projection optical system, the position with the bent state is easy. Can be specified. Therefore, it is possible to display such a position on a board | substrate in advance, or to warn that the part has a high risk of becoming bad after exposure, or to save it as data.

1 is a configuration diagram of a maskless exposure apparatus according to Embodiment 1 of the present invention.

It is a principal part perspective view of the wedge glass unit which concerns on this invention.

3 is a view seen from K of FIG.

4 is a configuration diagram of a maskless exposure apparatus according to Embodiment 2 of the present invention.

5 is a configuration diagram of the height detector.

6 is a cross-sectional view of the exposure substrate.

7 is an explanatory diagram of measurement light according to the present invention.

[Explanation of symbols on the main parts of the drawings]

(8) exposure substrate

(67) second projection lens

717 first wedge glass

727 second wedge glass

(717u) face of first wedge glass

(727u) face of second wedge glass

θ: angle of the inclined surfaces of the wedge glass 717, 727

δ: distance between plane 717u and plane 727u

Claims (3)

An exposure light source for outputting exposure illumination light, a two-dimensional spatial modulator, a first projection lens, a micro lens array, a second projection lens, and an exposure substrate, and moving in a direction perpendicular to the optical axis of the second projection lens; In a maskless exposure apparatus comprising a stage, Two wedge glass of the 1st wedge glass and the 2nd wedge glass whose one surface in the plate | board thickness direction is the surface which inclined angle (theta) with respect to the other surface of the plate | board thickness direction, and the moving means which moves at least one of the said 2 wedge glass. Install it, The other surface of the first wedge glass is disposed perpendicular to the optical axis of the second projection lens, and the one surface of the second wedge glass is predetermined in distance from the one surface of the first wedge glass. Combination is performed so as to be a losing value, and is disposed on the incident side or the exit side of the second projection lens, When the imaging position of the said 2nd projection lens in the said optical axis direction is shift | deviated from the surface of the said exposure board | substrate, the said distance means makes any one of the said wedge glass constant, and the said angle (theta) direction The maskless exposure apparatus which positions the imaging surface of the said 2nd projection lens on the surface of the said exposure substrate by moving to. The method of claim 1, Further comprising measuring means for measuring the surface height of the exposure substrate, The maskless exposure apparatus which measures the surface height of the said exposure board | substrate before exposure. The method of claim 2, The measuring means includes a light source for outputting measurement light that does not expose the photosensitive layer on the exposure substrate, light receiving means for receiving the measurement light reflected from the exposure substrate, and a reflecting portion according to a position received by the light receiving means. Equipped with a position sensor for calculating the height, And the light source irradiates the photosensitive layer to the photosensitive layer at a Brewster angle determined by the refractive index of the photosensitive layer.

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