A projection imaging system

Abstract

A projection imaging system comprises a first light source, a second light source, a beam combining element, a spatial light modulation element, a first optical element group, a microlens array and a second optical element group, the light beams emitted by the first light source and the second light source are combined into a combined light beam by the beam combining element, and projected to a work surface through the spatial light modulation element, the first optical element group, the microlens array and the second optical element group, the work surface has a photosensitive material, the light beam emitted by the first light source is a work light, the light beam emitted by the second light source is a catalytic light, the work light has a photosensitive reaction with the photosensitive material of the work surface, the catalytic light is used to reduce the minimum exposure energy of the photosensitive reaction of the work light with the photosensitive material, and the light energy of the catalytic light is several times of the light energy of the work light. The light energy of the catalytic light and the work light is coordinated, the effective size of the light spot is significantly reduced, and the resolution of the projection imaging system is improved.

Description

Technical Field

[0001] This invention relates to an optical projection system, and more particularly to a digital optical projection imaging system. Background Technology

[0002] DLP (Digital Light Processing) projection imaging systems are used in planar imaging fields such as semiconductors and PCBs. A DLP projection imaging system uses a computer-controlled digital micromirror array (DMD) to generate an image, which is then projected onto a photomask through a projection lens. The resolution of a DLP projection imaging system is limited by the size of the pixel units in the DMD. To further improve the resolution of the DLP projection imaging system, a microlens array is added to the projection lens. The microlens array can reduce the size of the DMD pixel units, improving the system's resolution, but this still cannot meet the resolution requirements of the DLP projection imaging system. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an optical projection system that improves resolution.

[0004] To address the aforementioned problems, this invention provides a projection imaging system comprising a first light source, a second light source, a beam combiner, a spatial light modulation element, a first optical element group, a microlens array, and a second optical element group. The light beams emitted by the first and second light sources are combined into a single beam by the beam combiner, and then projected onto a working surface via the spatial light modulation element, the first optical element group, the microlens array, and the second optical element group. The working surface has a photosensitive material. The light beam emitted by the first light source is the working light, and the light beam emitted by the second light source is the catalytic light. The working light undergoes a photosensitizing reaction with the photosensitive material of the working surface. The catalytic light is used to reduce the minimum exposure energy required for the working light to react with the photosensitive material, and the light energy of the catalytic light is several times that of the working light.

[0005] Furthermore, the light energy of the catalytic light is 3 to 20 times that of the working light.

[0006] Furthermore, the light energy of the working light is determined based on the light energy of the catalytic light and the effective spot size.

[0007] Furthermore, the light energy of the catalytic light is determined based on the limit that the optical element can withstand.

[0008] Furthermore, the minimum effective light energy of the catalytic light is determined based on the effective spot size, which is the desired effective spot size; or the light energy of the catalytic light is selected proportionally as the minimum effective light energy, and the effective spot size is determined based on the minimum effective light energy of the catalytic light and the distribution curve of the catalytic light energy. The proportion of the minimum effective light energy of the catalytic light is 40% to 85% of the light energy of the catalytic light.

[0009] Furthermore, the minimum effective light energy of the working light is determined based on the minimum effective light energy of the catalytic light, and the light energy of the working light is determined according to the minimum effective light energy of the working light, the distribution curve of the working light energy, and the effective spot size.

[0010] Furthermore, the light energy of the catalytic light is determined based on the effective spot size and the light energy of the working light.

[0011] Furthermore, the minimum effective light energy of the working light is selected according to a ratio, or determined based on the effective spot size and the distribution curve of the working light energy. The selection ratio of the minimum effective light energy of the working light is 10%-20% of the working light energy.

[0012] Furthermore, the minimum effective light energy value of the catalytic light is determined based on the minimum effective light energy of the working light, and the light energy value of the catalytic light is determined based on the minimum effective light energy value of the catalytic light, the effective light spot size, and the distribution curve of the catalytic light energy.

[0013] Furthermore, the projection imaging system also includes an autofocus system.

[0014] Furthermore, the projection imaging system also includes a beam splitting system.

[0015] Compared with the prior art, the projection imaging system of the present invention uses working light and catalytic light to act on the working surface at the same time. The catalytic light reduces the minimum exposure energy for the working light to react with the photosensitive material, and coordinates the light energy of the catalytic light and the working light, which significantly reduces the effective size of the light spot and achieves the purpose of improving the resolution of the projection imaging system. Attached Figure Description

[0016] Figure 1 This is the first embodiment of a projection imaging system.

[0017] Figure 2 This is a curve showing the distribution of light spot energy.

[0018] Figure 3 This is the second embodiment of the projection imaging system.

[0019] Figure 4 This is the third embodiment of the projection imaging system. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described below with reference to specific embodiments shown in the accompanying drawings.

[0021] like Figure 1 As shown, a projection imaging system includes a first light source 1, a second light source 2, a beam combiner 3, a spatial light modulation element 4, a first optical element group 5, a microlens array 6, and a second optical element group 7. The light beams emitted by the first light source 1 and the second light source 1 are combined into a combined beam by the beam combiner 3. The combined beam is then passed through the spatial light modulation element 4 to form a projection pattern beam. The projection pattern beam is projected onto the microlens array 6 via the first optical element group 5, and a focused spot is formed by the microlens array 6. The focused spot is then projected onto a working surface 8 via the second optical element group 7. The working surface 8 has a photosensitive material. The beam combiner 3 can be a beam splitter, transmitting the light beam from the first light source and reflecting the light from the second light source. The spatial light modulation element can be a digital micromirror array.

[0022] The beam emitted by the first light source 1 is the working light, which can be a single-band ultraviolet light source or a multi-band ultraviolet light source as needed. The beam emitted by the second light source 2 is the catalytic light, which can be an infrared light source. The working light reacts with the photosensitive material of the working surface 8, and the catalytic light 2 is used to reduce the minimum exposure energy required for the working light 1 to achieve a sufficient photosensitivity reaction with the photosensitive material. Figure 2 As shown, the microlens array 6 focuses the working light spot. The energy distribution of the working light spot is high in the middle and low at the edges. For the working light 1 to have a sufficient photosensitivity reaction with the photosensitive material, the light energy of the working light 1 acting on the photosensitive material needs to reach a certain value. If it is lower than this value, the photosensitivity reaction cannot fully affect the photosensitive material, and the photosensitivity reaction is incomplete. The effective area where the working light 1 can have a sufficient photosensitivity reaction with the photosensitive material is d. The energy distribution of the catalytic light spot is the same as that of the working light 1, with a high center and low edges. Similarly, the catalytic light 2 has the best catalytic effect only when the light energy reaches a certain intensity. The light energy of the catalytic light 2 is several times that of the working light 1. Preferably, the light energy of the catalytic light 2 is 3 to 20 times that of the working light 1. The effective spot diameter of the catalytic light is d2. When the working light 1 and the catalytic light 2 work on the working surface at the same time, the catalytic light 2 effectively reduces the light energy of the working light 1 required for a full photosensitivity reaction, thereby reducing the effective spot size of the working light 1, improving the resolution level, and reducing the actual photolithography spot size d3.

[0023] In application, the light energy of the catalytic light 2 is first determined based on the limits that the optical elements in the projection imaging system can withstand. The effective spot size D is the required effective spot size, which can be determined by the required resolution. The minimum effective light energy of the catalytic light 2 is determined based on the effective spot size D; alternatively, 40% to 85% of the light energy of the catalytic light 2 can be selected as the minimum effective light energy of the catalytic light 2. The effective spot size D is then determined based on the minimum effective light energy of the catalytic light 2 and the distribution curve of the catalytic light energy. The light energy of the working light 1 is then determined based on the effective spot size D and the minimum effective light energy of the catalytic light 2. The minimum effective light energy of the working light 1 is the minimum light energy value that, after superimposing the minimum effective light energy of the catalytic light 2, can achieve an optical reaction with the photosensitive material of the working surface 8. The spot size of the minimum effective light energy of the working light 1 is D. The light energy of the working light 1 is determined based on the minimum effective light energy of the working light 1, the distribution curve of the working light energy, and the effective spot size D. The effective spot size of the working light and the catalytic light are the same, both being D.

[0024] In the above method, the light energy of the catalytic light 2 is determined based on the limit that the optical element can withstand, thereby determining the effective spot size D and the light energy of the working light. Other methods can also be used to determine the effective spot size D, the catalytic light energy, and the working light energy. For example, the light energy of the working light 1 can be determined first, and the light energy of the catalytic light 2 can be determined based on the light energy of the working light 1 and the effective spot size D. The minimum effective light energy of the working light 1 can be determined based on the distribution curve of the effective spot size and the working light energy, or the light energy of the working light can be selected as the minimum effective light energy at a certain ratio. Typically, 10%-20% of the working light energy value is used as the minimum effective light energy value of the working light to improve its utilization rate. The effective spot size is determined based on the minimum effective light energy of the working light and its distribution curve. The minimum effective light energy value of the catalytic light 2 is determined based on the minimum effective light energy of the working light 1. The minimum effective light energy of the catalytic light 2 is the minimum light energy value that, when superimposed with the minimum effective light energy of the working light 1, can undergo an optical reaction with the photosensitive material of the working surface 8. The light energy value of the catalytic light 2 is determined based on the minimum effective light energy value, the effective spot size D, and the distribution curve of the catalytic light energy.

[0025] like Figure 3As shown, the projection imaging system also includes an autofocus system 9, which comprises two wedge prisms 90. The two wedge prisms 90 form a parallel plate in the z-direction. By moving the two wedge prisms 90 relative to each other, the distance between the upper and lower planes 91 and 92 of the autofocus system in the z-direction is changed, thereby adjusting the focal plane of the lens. The autofocus system can change the distance between the upper and lower planes 91 and 92 of the autofocus system in the z-direction by moving one or both wedge prisms in the y-direction, such that one wedge prism moves relative to the other along an inclined plane, or both wedge prisms move along an inclined plane.

[0026] like Figure 4 As shown, the projection imaging system also includes a beam splitting system 10, which can achieve lateral expansion of the light spot, thereby increasing the working area of ​​a single scan by the lens. Taking the beam splitting system 10 splitting the light emitted from the second optical element group 7 or the autofocus system 9 into two beams as an example, the beam splitting system 10 includes two sets of optical elements 110 and 120. The two sets of optical elements 110 and 120 have opposite tilt directions relative to the imaging surface 8, and both sets of optical elements 110 and 120 have tilt angles in the x and y directions. Each set of optical elements 110 and 120 corresponds to a light path, forming an imaging area on the imaging surface 8. Because the two sets of optical elements 110 and 120 have tilt angles in both the x and y directions, the imaging areas formed by the two sets of elements 110 and 120 have relative displacement in both the x and y directions.

[0027] Each set of optical elements 110, 120 includes two parallel and opposite first reflecting surfaces 111, 121 and second reflecting surfaces 112, 122. Both the first reflecting surfaces 111, 121 and the second reflecting surfaces 112, 122 have a certain angle with the imaging surface 8, and both the first and second reflecting surfaces have tilt angles in the X and Y directions. The first reflecting surfaces 111, 121 face the second optical component or the autofocus system, receive light, and reflect it to the second reflecting surfaces 112, 122. The second reflecting surfaces 112, 122 reflect the light to the imaging surface 8, forming an imaging area on the imaging surface 8.

Claims

1. A projection imaging system, characterized in that: The projection imaging system includes a first light source, a second light source, a beam combiner, a spatial light modulation element, a first optical element group, a microlens array, and a second optical element group. The light beams emitted by the first and second light sources are combined into a combined beam by the beam combiner, and then projected onto a working surface by the spatial light modulation element, the first optical element group, the microlens array, and the second optical element group. The working surface has a photosensitive material. The light beam emitted by the first light source is the working light, and the light beam emitted by the second light source is the catalytic light. The working light reacts with the photosensitive material of the working surface. The catalytic light is used to reduce the minimum exposure energy required for the working light to react with the photosensitive material. The light energy of the catalytic light is several times that of the working light.

2. The projection imaging system according to claim 1, characterized in that: The light energy of the catalytic light is 3 to 20 times that of the working light.

3. The projection imaging system according to claim 1, characterized in that: The light energy of the working light is determined based on the light energy of the catalytic light and the effective spot size.

4. The projection imaging system according to claim 3, characterized in that: The light energy of the catalytic light is determined based on the limit that the optical element can withstand.

5. The projection imaging system according to claim 3, characterized in that: The minimum effective light energy of the catalytic light is determined based on the effective light spot size, which is the required effective light spot size; or the light energy of the catalytic light is selected proportionally as the minimum effective light energy of the catalytic light, and the effective light spot size is determined based on the minimum effective light energy of the catalytic light and the distribution curve of the catalytic light energy.

6. The projection imaging system according to claim 5, characterized in that: The minimum effective light energy of the catalytic light is selected as 40% to 85% of the light energy of the catalytic light.

7. The projection imaging system according to claim 5 or 6, characterized in that: The minimum effective light energy of the working light is determined based on the minimum effective light energy of the catalytic light. The light energy of the working light is determined according to the minimum effective light energy of the working light, the distribution curve of the working light energy, and the effective spot size.

8. The projection imaging system according to claim 1, characterized in that: The light energy of the catalytic light is determined based on the effective spot size and the light energy of the working light.

9. The projection imaging system according to claim 8, characterized in that: The minimum effective light energy of the working light is selected according to a ratio, or determined based on the effective spot size and the distribution curve of the working light energy.

10. The projection imaging system according to claim 9, characterized in that: The minimum effective light energy of the working light is selected as 10%-20% of the light energy of the working light.

11. The projection imaging system according to claim 8, characterized in that: The minimum effective light energy value of the catalytic light is determined based on the minimum effective light energy of the working light, and the light energy value of the catalytic light is determined based on the minimum effective light energy value of the catalytic light, the effective light spot size, and the distribution curve of the catalytic light energy.

12. The projection imaging system according to claim 1, characterized in that: The projection imaging system also includes an autofocus system.

13. The projection imaging system according to claim 1, characterized in that: The projection imaging system also includes a beam splitting system.

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