Method and device for exposure of photosensitive layer

Abstract

A method for exposing a light-sensitive layer to light using an optical system, wherein at least one light beam is generated by respectively at least one light source and pixels of an exposure pattern grid are illuminated by at least one micro-mirror device with a plurality of micro-mirrors. An affine distortion takes place, in particular a shearing, of the exposure pattern grid.

Claims

1. A method for exposing a light-sensitive layer to light using an optical system, said method comprising: directing at least one light beam generated by at least one light source, respectively, to at least one micro-mirror device having one or more micro-mirrors to respectively illuminate one or more pixels to generate an image of the micro-mirror device; and effecting, via two cylinder lenses, a shearing of the generated image to form horizontal and/or vertical exposure pattern grid lines of a pattern grid to which the light-sensitive layer is exposed, each of the cylinder lenses having a cylinder axis, wherein greater than 50% of an energy of each of the pixels is found in a field of the light-sensitive layer having an image that directly corresponds with the pixel, and wherein a remaining amount of the energy of each of the pixels is distributed across adjacent fields to the field having the image that directly corresponds with the pixel.

2. The method according to claim 1, wherein the method includes arranging the horizontal and/or vertical exposure pattern grid lines obliquely.

3. The method of claim 1, wherein the two cylinder lenses are combined to form a compound lens.

4. A device for exposing a light-sensitive layer to light, the device comprising: at least one light source for respectively generating at least one light beam, at least one micro-mirror device toward which the light beam is directed by the light source, the micro-mirror device having one or more micro-mirrors configured to respectively illuminate one or more pixels to generate an image of the micro-mirror device, two cylinder lenses, each cylinder lens having a cylinder axis, the cylinder lenses being configured to effect a shearing of the generated image to form horizontal and/or vertical exposure pattern grid lines of a pattern grid to which the light-sensitive layer is exposed, wherein greater than 50% of an energy of each of the pixels is found in a field of the light-sensitive layer having an image that directly corresponds with the pixel, and wherein a remaining amount of the energy of each of the pixels is distributed across adjacent fields to the field having the image that directly corresponds with the pixel.

5. The device of claim 4, wherein the two cylinder lenses are combined to form a compound lens.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a first embodiment of the device according to the invention,

(2) FIG. 2 shows a second embodiment of the device according to the invention,

(3) FIG. 3 shows a third embodiment of the device according to the invention,

(4) FIG. 4a shows a schematic not-to-scale view of a DMD (micro-mirror device) with an enlarged partial section with micro-mirrors in a first position,

(5) FIG. 4b shows a schematic not-to-scale view of a DMD (micro-mirror device) with an enlarged partial section with micro-mirrors in a second position,

(6) FIG. 5a shows a schematic not-to-scale enlarged view of a first embodiment of an exposure pattern according to the invention,

(7) FIG. 5b shows a schematic not-to-scale enlarged view of a first embodiment of an exposure pattern according to the invention,

(8) FIG. 6 shows a schematic view of an exposure pattern distorted by optical elements

(9) In the figures identical components or components having the same function are marked with identical reference symbols.

DETAILED DESCRIPTION OF THE INVENTION

(10) FIG. 1 shows a first embodiment comprised of an optical system 8 with at least one light source 7 and at least one DMD 1 (micro-mirror device) and a substrate holder 11. The substrate holder 11 can be moved in relation to a coordinate system K3.

(11) Using fixing means 13 a substrate 10 is fixed to the substrate holder 11, the substrate 10 having a light-sensitive layer 9 from an exposable material on it, which is exposed to light by means of the device.

(12) The origin of a fixed-sample coordinate system K2 (i.e. fixed to the substrate 10/the light-sensitive layer 9) is preferably placed in the centre of the surface 9o of layer 9.

(13) A light beam 6 (primary beam), which is emitted by the light source 7 and, on the way to the DMD 1, may pass a number of optical elements (not shown), is changed by the DMD 1 into a structured light beam 6 (secondary beam). The beam may pass a number of optical elements, such as two cylinder lenses 12, 12, on the way to the layer 9.

(14) Using a semi-transparent mirror 14 a detector 19, in particular a camera, more preferably a CCD or CMOS camera, may directly detect and/or measure the surface 9o of the layer 9 to be exposed. The measuring results are preferably used to directly control the process and/or calibrate the device. In the description below and in the further figures a depiction of these measuring means has for clarity's sake been omitted. The measuring means according to the invention may however be used in any of the said inventive embodiments.

(15) FIG. 2 shows a second embodiment, wherein here the optical system 8 is provided with two light sources 7, 7. Light beams 6 are emitted by both light sources 7, 7. One of the light beams 6 is deflected by a mirror 14 to go to the beam splitter 14 and by means thereof is united with the light beam 6 of the second light source 7.

(16) The united light beam 6 is guided to the DMD 1 and converted by the same into a structured light beam 6, which again, on the way to layer 9, may pass a number of optical elements such as two cylinder lenses 12, 12.

(17) One, in particular autonomous, inventive aspect is that, above all, the two light sources 7 may be different with regard to radiation intensity, wavelength, coherence length and possibly further properties or parameters, so that a laser beam 6 with a plurality of different optical parameters can be generated.

(18) According to the invention in particular more than two light sources, in particular more than 5, more preferably more than 10, most preferably more than 20 light sources 7, 7 may be used. Each light source may preferably be a LED field or a laser diode (LD) field.

(19) FIG. 3 shows a third embodiment comprised of an optical system 8 with at least one light source 7 and two DMDs 1.

(20) A light beam 6 is emitted by the light source 7 and split by a beam splitter 14. A first split beam 6.1 is modified by a first DMD 1 to result in a first modified beam 6.1. The layer 9 is exposed to this first modified beam 6.1. The second split beam 6.2 is deflected by means of a mirror 14 in direction of a second DMD 1 and is then directed as a second modified beam 6.2 to the layer 9. Preferably the second modified beam 6.2 is directed at a position in the layer 9, which is different from the position at which the first modified beam 6.1 is directed. All said beams may pass through a number of optical elements, such as two cylinder lenses 12, 12.

(21) One, in particular autonomous, inventive aspect is that at least two DMDs 1 are used by means of which two positions of layer 9 can be exposed simultaneously, wherein preferably a single, in particular united, beam is used for acting on the DMDs. This leads, in particular, to a widening of the exposed section, in particular the exposed strip, and thus to an increase in throughput.

(22) FIG. 4a shows the DMD 1 with a mirror surface 2. The enlarged view of a part of the mirror surface 2 shows several (16) mirrors 3 of a plurality of mirrors 3. The mirrors are arranged in a non-tilted alignment called the starting position. The DMD 1 is assigned to a coordinate system K1. The Z-axis of K1 (i.e. K1z) extends normal to the mirror surface 2, the x-coordinate and the y-coordinate extend in parallel to the mirror surface edges 2kx and 2ky of the mirror surface 2 and define a mirror plane.

(23) FIG. 4b shows the same DMD 1, wherein one of the mirrors 3 is arranged in a position tilted or rotated about the x-axis. The part of the beam 6 hitting the tilted mirror 3 is therefore reflected in a direction which is not identical to the reflection direction of the parts of the beam 6 reflected by the non-tilted mirrors 3.

(24) FIG. 5a shows a first less preferred inventive exposure pattern 24, which in both mutually orthogonal directions K2x, K2y, is at equidistant distances from the exposure pattern grid lines. The exposure pattern 24 is thus isotropic and homogeneous in both directions K2x and K2y.

(25) FIG. 5b shows a second more preferred exposure pattern 24 according to the invention, which has, for each direction, its own equidistant direction-related distance between the exposure pattern grid lines. The exposure pattern 24 is thus isotropic, but homogeneous in each of directions K2x and K2y.

(26) It is also feasible for exposure to take place at exposure pattern grid line intersections 25 and/or exposure pattern partial surfaces 26, 26, 26 and not within individual grid surfaces.

(27) The different exposure patterns 24, 24, 24 can in particular be created/modified by means of optical elements mounted upstream and/or downstream of the DMD 1 such as the two cylinder lenses 12, 12 illustrated downstream of the DMD 1 in FIGS. 1-3. The DMD 1 illustrated in FIGS. 1-4b would preferably be isotropic and homogeneous, wherein the, particularly the downstream, optical elements, such as the two cylinder lenses 12, 12 illustrated downstream of the DMD 1 in FIGS. 1-3, are constructed to effect an anisotropic and/or homogeneous imaging of the DMD.

(28) FIG. 6 shows a schematic not-to-scale top view of an exposure pattern 24 distorted in particular, by optical elements of the optical system 8, such as the two cylinder lenses 12, 12 illustrated downstream of the DMD 1 in FIGS. 1-3.

(29) The optical elements, such as the two cylinder lenses 12, 12 illustrated downstream of the DMD 1 in FIGS. 1-3, cause the partial beams reflected by the mirrors 2 of the DMD 1 to be orthogonally reflected in direction of the layer 9 to be exposed, however a distortion takes place, preferably exclusively, within the K2x-K2y plane. Due to this method according to the invention an exposure pattern 24 can be optically created which leads to an inventive increase in the overlay. The DMD 1 in this embodiment is preferably not positioned obliquely, rather the original image of the DMD 1 undergoes an affine distortion in order to achieve the oblique position of the exposure pattern 24.

LIST OF REFERENCE SYMBOLS

(30) 1 DMD 2 mirror surface 2kx, 2ky mirror surfaces edges 3 mirror 6 light beam (beam) 6 modified/structured beam 6.1 first split beam 6.1 first modified beam 6.2 second split beam 6.2 second modified beam 7,7 light source 8 optical system 9 layer 9o surface of the layer 10 substrate 11 substrate holder 12, 12 cylinder lenses 13 fixing means 14 mirror 14 beam splitter 14 semi-transparent mirror 19 detector 23 pixel 24, 24, 24 exposure pattern grid 25 exposure pattern grid line intersection 26, 26, 26 exposure pattern partial surface K1, K2, K3 coordinate systems K2x, K2y mutually orthogonal directions