CN111381456A

CN111381456A - Maskless lithography system and real-time image plane focus detection method

Info

Publication number: CN111381456A
Application number: CN202010356647.3A
Authority: CN
Inventors: 徐珍华; 李源; 汪孝军; 阮立锋
Original assignee: Zhongshan Aiscent Technologies Co ltd
Current assignee: Zhongshan Aiscent Technologies Co ltd
Priority date: 2020-04-29
Filing date: 2020-04-29
Publication date: 2020-07-07

Abstract

The invention discloses a maskless photoetching system and an image plane focus real-time detection method. The maskless lithography system includes: a DMD module (101); an illumination module (102) which projects the light beam to the first region (101-1) for lithography imaging and a second region (101-2) for projecting the image plane detection pattern of the DMD module (101); the light beam that divides light reflecting mirror group (103), focal plane detection camera module (104) and lithography lens (105), the exposure base plate (106) that scribbles photosensitive material is thrown through dividing light reflecting mirror group (103) and lithography lens (105) to the light beam that DMD module (101) reflect, return to the department of dividing light reflecting mirror group through the reflection of exposure base plate again, by dividing light reflecting mirror group with light reflection to focal plane detection camera module, whether the position of exposure base plate was out of focus this moment is judged through the image quality who gathers to focal plane detection camera module.

Description

Maskless lithography system and real-time image plane focus detection method

Technical Field

The invention relates to the technical field of photoetching, in particular to a maskless photoetching system and an image plane focus real-time detection method.

Background

The Digital maskless lithography technology based on the Digital micromirror array (DMD) spatial light modulator greatly simplifies the complicated flow of the traditional lithography mask manufacturing process, so that the manufacturing of a novel Digital lithography mask becomes simple and easy to control, the complexity of lithography patterns is obviously improved, and the precision and the efficiency of lithography are further improved.

A DMD digital maskless lithography system is a mature prior art, and as shown in fig. 1, its basic structure includes a light source 1, a DMD spatial light modulator 2, a half-reflecting and half-transmitting prism 3, a projection lens 4 and a CCD focusing camera 6. The DMD digital maskless lithography system uses a computer to optimize a DMD spatial light modulator to generate a series of virtual digital patterns as virtual masks, and controls a projection lens to project the patterns onto a lithography substrate (also called an exposure substrate) which is superposed with a focal plane of the projection lens in a width manner so as to carry out photoetching on the substrate.

The reflected light on the surface of the substrate returns along the projection lens 4 and enters the CCD focusing camera 6 after being reflected by the semi-reflecting and semi-transmitting prism 3. And a CCD focusing camera or a microscope or other observation equipment is used for carrying out digital information acquisition on the light field distribution pattern on the photoetching substrate so as to optimize the image output by the DMD. By analyzing whether the pattern information on the photoetching substrate meets the expected requirement or not, the structure of the next digital pattern to be projected can be further pre-regulated and optimized, and the optimal photoetching pattern quality can be finally obtained through the feedback and optimization process.

In the above process, the lithography substrate is firstly required to be located on the focal plane of the projection lens 4, and meanwhile, the conjugate of the focal plane of the CCD focusing camera and the DMD spatial light modulator 2 is also ensured, so that the CCD focusing camera can also take a picture clearly while the lithography precision is ensured. Therefore, in the DMD digital maskless lithography system, the focal plane position of the CCD focusing camera is first calibrated before the lithography operation is formally started. In general, a glass plate 5 as shown in FIG. 2 is used as a projection object plane, and one side of the glass plate 5 is a reflecting mirror 5-1 and the other side thereof is a transparent glass 5-2. The emergent light of the light source 1 is reflected by the DMD spatial light modulator to project a DMD stripe pattern with alternate light and shade, the DMD stripe pattern is projected to the upper end face of the glass plate 5 by the projection lens 4, and half of the DMD stripe pattern is reflected by the reflector 5-1 at one side of the glass plate 5, returns along the projection lens 4 and enters the CCD focusing camera 6 through the reflection of the semi-reflecting and semi-transparent prism 3. Half of the DMD fringe pattern is directly transmitted through the clear glass 5-2 on the other side of the focusing glass plate 5 and is incident into the microscope 7 for auxiliary focusing.

Focusing is performed on the basis of the above. Finally, when the image on the glass plate observed by the microscope is clear, and when the CCD focusing camera 6 can image clearly, then it can be determined that: the glass plate 5 has been brought into coincidence with the focal plane 9 of the projection lens 4, and the focal plane 9 of the projection lens 4 at this time has been brought into coincidence with the focal plane of the CCD focus camera 6 determined by the glass plate 5. Thus, the focus calibration operation is completed, and the substrate etching operation can be performed.

The method in the prior art can ensure better focusing and imaging precision to a certain extent. However, in order to ensure the focusing accuracy, the substrate etching operation needs to be periodically stopped to perform the above-described focusing operation. Thereby influencing the working efficiency to a greater extent and reducing the production efficiency of the equipment. In addition, if the focusing precision is reduced or the imaging is out of focus due to the system disturbance in the substrate etching production process between two times of focusing, the real-time detection and the timely adjustment cannot be realized. This will seriously affect the yield of the production process.

Disclosure of Invention

The present invention is directed to a method for real-time detection of image plane focus during DMD scanning to overcome or at least alleviate at least one of the above-mentioned disadvantages of the prior art.

To achieve the above object, the present invention provides a maskless lithography system, comprising: the DMD module is provided with a first area for photoetching imaging and a second area for projecting an image surface detection graph;

an illumination module projecting a light beam to the first and second areas of the DMD module;

the light beam reflected by the DMD module is projected to an exposure substrate coated with a photosensitive material through the light splitting reflector group and the photoetching lens for maskless photoetching, and then is reflected back to the light splitting reflector group through the reflection of the exposure substrate, the light is reflected to the focal plane detection camera module through the light splitting reflector group, and the focal plane detection camera module judges whether the position of the exposure substrate is out of focus at the moment through the acquired image quality. And after determining the focus, performing focusing. Any suitable method may be used for focusing. For example, production of an exposure substrate may be stopped to perform focusing.

The focal plane detection camera module comprises a CCD focusing camera, for example. The CCD focusing camera is used for detecting a focal plane. In one embodiment of the present invention, a CCD focusing camera is used for both focal plane detection and digital information acquisition of the light field distribution pattern on the photolithographic substrate. Thus, the image output by the DMD can be optimized based on the captured etch pattern. Specifically, by analyzing whether the etching pattern information on the lithography substrate meets the expected requirements, the next or subsequent multiple digital patterns to be projected can be optimized and/or pre-regulated, and the optimal lithography pattern quality can be finally obtained through the feedback and optimization process according to the collected optical field distribution pattern on the exposure substrate.

Preferably, the light reflected by the DMD module passes through the lithography lens and then is projected to the light splitting mirror group, and then is projected to the exposure substrate, and the maskless lithography system further includes an optical path adjusting device disposed between the light splitting mirror group and the focal plane detection camera module, so that the focal plane detection optical path and the maskless lithography optical path are imaged at the same focal plane position. The optical path adjusting device enables the scanning photoetching optical system and the detection focal plane CCD system to be at the same image surface position, namely, the focal plane difference caused by the wavelength difference is calibrated to be the same as the focal plane position. Or not, in the focal plane monitoring process, the distance for locking the positions of the two image planes is fixed.

Preferably, the light reflected by the DMD module passes through the light splitting mirror group and then is projected to the lithography lens, wherein an imaging lens is disposed in the focal plane detection camera module.

Preferably, the illumination module comprises an exposure light source and a focal plane detection light source, the exposure light source is used for maskless lithography, the focal plane detection light source is used for focal plane detection,

the exposure light source and the focal plane detection light source are different light sources with different wavelengths, a photosensitive material coated on the exposure substrate does not sense the focal plane detection light source, the exposure light source only illuminates a first area of the DMD module, and the focal plane detection light source only illuminates a second area of the DMD module; or

Wherein, the exposure light source and the focal plane detection light source are the same light source with the same wavelength.

Preferably, the first area of the DMD module and the second area of the DMD module are periodically used interchangeably.

Preferably, the maskless lithography system further includes a microlens array, a secondary imaging optical lens, a second dichroic mirror set, and a second focal plane detection camera module. Microlenses are optical structures in a lithography system that increase the lithographic minimum linewidth spacing.

The micro lens array is arranged at the image side of the photoetching lens or the beam splitting reflector group, and the light blocking layer of the micro lens array deviates from the exposure substrate,

the secondary imaging optical lens and the second beam splitting reflector group are arranged between the micro lens array and the exposure substrate on an optical path, and the second focal plane detection camera module receives light beams emitted by the second beam splitting reflector group.

Thus, two detection optical paths are formed, and the image surface positions of the upper imaging system and the lower imaging system are detected respectively.

Preferably, a detection pattern is etched on the surface of the light blocking layer of the microlens array. Light reflected by the light blocking layer of the micro-lens array reaches the focal plane detection camera module after passing through the optical system, so that the focal plane condition of the upper imaging system is monitored.

Preferably, the light transmitted by the micro lens array passes through the secondary imaging optical lens and then is projected to the second dichroic mirror group; and/or

The light transmitted by the micro lens array passes through the second light splitting reflector group and then is projected to the secondary imaging optical lens.

The invention also provides a real-time detection method of the image plane focus, which comprises the following steps:

step S1, projecting a light source beam to a DMD module, wherein a first area of the DMD module reflects a first pattern for photoetching imaging, and a second area of the DMD module reflects a second pattern for image plane detection;

step S2, performing maskless lithography on the exposure substrate coated with photosensitive material, and simultaneously, collecting the image of the second pattern on the exposure substrate by the focal plane detection camera module, wherein the light beam reflected by the DMD module is projected to the exposure substrate for maskless lithography through the beam splitting mirror group and the lithography lens, and then reflected back to the beam splitting mirror group through the reflection of the exposure substrate, and then reflected to the focal plane detection camera module by the beam splitting mirror group,

in step S3, the focal plane detection camera module analyzes the image quality of the captured second pattern imaged on the exposed substrate, and determines whether the position of the exposed substrate is out of focus based on the analysis result.

Preferably, the step S2 further includes: the focal plane detection camera module acquires the image of the first pattern on the exposure substrate, and

step S3 further includes: the focal plane detection camera module analyzes the image quality of the acquired first pattern imaged on the exposure substrate, and judges whether the next or more subsequent first patterns to be projected need to be optimized or not based on the analysis result.

Preferably, the micro-lens array, the secondary imaging optical lens, the second beam splitting reflector group and the second focal plane detection camera module are arranged. Microlenses are optical structures in a lithography system that increase the lithographic minimum linewidth spacing. Wherein the micro lens array is arranged at the image side of the photoetching lens or the beam splitting reflector group, and the light blocking layer of the micro lens array deviates from the exposure substrate,

the secondary imaging optical lens and the second beam splitting reflector group are arranged between the micro lens array and the exposure substrate on an optical path, the second focal plane detection camera module receives light beams emitted by the second beam splitting reflector group, and the second focal plane detection camera module judges whether the position of the exposure substrate is out of focus or not through the collected image quality.

Due to the adoption of the technical scheme, the invention has the following advantages: the focusing condition is detected in the substrate etching production process, and the focusing precision is ensured without stopping the substrate etching work for focusing. Thereby greatly improving the working efficiency and the production efficiency of the equipment. In addition, the yield of the production process is improved.

Drawings

FIG. 1 is a schematic diagram of a method for calibrating the coincidence between the focal plane of a projection lens and the focal plane of a CCD camera in a DMD digital maskless lithography system in the prior art.

FIG. 2 is a schematic view of a structure of a flat glass sheet used in the calibration method in the method shown in FIG. 1.

FIGS. 3 and 4 are schematic diagrams of the detection of the focal plane of a maskless lithography optical system without MLA (micro lens array) according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of an area of a spatial light modulator DMD chip in the DMD control module;

FIG. 6 is a schematic diagram of the optical path principle of the optical system with MLA of the present invention with a detection camera;

FIG. 7 is a schematic view of the imaging principle of FIG. 6;

FIG. 8a is a schematic focusing diagram of the case where the focusing wavelength is the same as the operating wavelength;

FIGS. 8b and 8c are schematic views of an imaging focal plane in the case where the focusing wavelength is different from the operating wavelength;

fig. 9 is a schematic view of a microlens array.

Fig. 10 is a diagram showing detection focusing optical path imaging focal plane positions in different cases of wavelength combinations of the exposure light source and the focal plane detection light source.

Reference numerals:

101	DMD module	109	The second beam splitter mirror group
				102	Lighting module	110	Second focal plane detection camera module
103	Light splitting reflector group	101-1	First region
				104	Focal plane detection camera module	101-2	Second region
105	Photoetching lens	107-1	Light-blocking layer
				106	Exposure substrate	107-2	Micro-lens
107	Microlens array	107-3	Detecting a pattern
				108	Secondary imaging optical lens

Detailed Description

The invention is described in detail below with reference to the figures and examples.

As shown, a maskless lithography system according to an embodiment of the present invention includes: a DMD module 101, an illumination module 102, a beam splitter mirror group 103, a focal plane detection camera module 104, and a lithography lens 105. The DMD module 101, the illumination module 102, the spectroscopic mirror assembly 103, the focal plane detection camera module 104, and the lithography lens 105 may be of any suitable structure, size, and operation, and may be a single component or an assembly of multiple components.

The DMD module 101 is used to emit a light beam to form a specific pattern. Typically, the DMD module 101 is controlled by a control system to form a specific pattern; it may also carry its own control system. Referring to fig. 5, the DMD module 101 has a first region 101-1 for photolithography imaging and a second region 101-2 for projecting an image plane detection pattern. It should be noted that the division of the first area and the second area is not limited to the form of fig. 5. Furthermore, in an alternative embodiment, the first area of the DMD module 101 and the second area of the DMD module 101 are used interchangeably at regular intervals. For example, a post-etch swap is performed for a set duration of time; or after a set number of etches.

The illumination module 102 serves as a light source that projects light beams to the first area 101-1 and the second area 101-2 of the DMD module 101.

The beam splitting mirror group 103 may be, for example, a semi-reflective and semi-transparent prism. The focal plane detection camera module 104 includes, for example, a CCD camera, and particularly a CCD focusing camera with a pattern analysis function. The lithography lens 105 may have a single or multiple lenses, or a single or multiple lens groups. The lithography lens 105 may be fixed focus or may be adjustable. For example, in the case of defocus, focus is adjusted by adjusting the lithography lens.

The light beam reflected by the DMD module 101 is projected to an exposure substrate 106 coated with a photosensitive material through a spectroscopic mirror group 103 and a lithography lens 105 for maskless lithography, and is reflected back to the spectroscopic mirror group 103 through the reflection of the exposure substrate 106, and the spectroscopic mirror group 103 reflects the light to a focal plane detection camera module 104. The focal plane detection camera module 104 determines whether the position of the exposure substrate 106 is out of focus at this time according to the quality of the acquired image. And after determining the focus, performing focusing. Any suitable method may be used for focusing. For example, production of an exposure substrate may be stopped to perform focusing.

Usually, a scanning manner is adopted to realize the imaging of the DMD module 101 on the exposed substrate 106, that is, to complete the imaging of the exposed substrate for one time, multiple or multiple frames of patterns output by the DMD module 101 are required (for example, the DMD module 101 outputs m × n patterns to complete the imaging of the exposed substrate for one time, where m is the number of rows and n is the number of columns), which is beneficial to improving the etching precision and reducing the size requirement on the DMD module. The pattern output by one DMD module 101 may also be used to image corresponding to a single exposure substrate, which is beneficial to increase the production efficiency, but has higher requirement for the size of the DMD module.

The CCD focusing camera is used for detecting a focal plane. Further, in an alternative embodiment of the present invention, a CCD focusing camera is used for both focus plane detection and digital information acquisition of the optical field distribution pattern etch pattern on the photolithographic substrate. Thus, the image output by the DMD can be optimized based on the captured etch pattern. Specifically, by analyzing whether the etching pattern information on the lithography substrate meets the expected requirements, the next or subsequent multiple digital patterns to be projected can be optimized and/or pre-regulated, and the optimal lithography pattern quality can be finally obtained through the feedback and optimization process according to the collected optical field distribution pattern on the exposure substrate. The analysis function may be performed partially or entirely in the focal plane detection camera module, or partially or entirely in a host computer in communication with the focal plane detection camera module or the CCD focusing camera.

In an alternative embodiment of the present invention, the light reflected by the DMD module 101 passes through the lithography lens 105, then is projected to the beam splitter mirror 103, and then is projected to the exposure substrate 106 (see fig. 3). In another optional embodiment of the present invention, the light reflected by the DMD module 101 passes through the spectroscopic mirror assembly 103 and then is projected to the lithography lens 105 (see fig. 4), wherein an imaging lens is disposed in the focal plane detection camera module 104.

The maskless lithography system further comprises an optical path length adjusting device. The optical path adjusting device is arranged between the light splitting reflector group 103 and the focal plane detection camera module 104, so that the focal plane detection optical path and the maskless lithography optical path are imaged at the same focal plane position. The optical path adjusting device enables the scanning photoetching optical system and the detection focal plane CCD system to be at the same image surface position, namely, the focal plane difference caused by the wavelength difference is calibrated to be the same as the focal plane position. It should be noted that calibration may also be performed without using an optical path adjusting device, and in the focal plane monitoring process, the distance for locking the positions of the two image planes is fixed. That is, the analysis determines whether defocus is generated in consideration of the fixed deviation. For example, in the case of using different wavelengths, in the case where the deviation in fig. 8b or 8c is a corresponding fixed distance, even if the focal planes are separated, it can be considered that the in-focus state is present. In other words, the calibration is performed digitally.

The illumination module 102 includes an exposure light source for maskless lithography and a focal plane detection light source for focal plane detection. In an alternative embodiment, the exposure light source and the focal plane detection light source are different light sources with different wavelengths, the photosensitive material coated on the exposure substrate 106 is not sensitive to the focal plane detection light source, the exposure light source only illuminates the first area of the DMD module 101, and the focal plane detection light source only illuminates the second area of the DMD module 101. In another alternative embodiment, the exposure light source and the focal plane detection light source are the same light source of the same wavelength. This alternative embodiment is particularly suitable for the case where the pattern output by one frame of the DMD module 101 corresponds to the imaging of a single exposure substrate, or the case with a microlens array.

FIGS. 3 and 4 are schematic diagrams of the detection of the focal plane of a maskless lithography system without MLA (micro lens array). The maskless lithography system (mainly its optics, not shown circuitry) comprises a DMD module 101 (with or without corresponding control unit), an illumination module 102 (or shaping illumination module) 102, a set of beam splitting mirrors 103, a focal plane detection camera module 104 (with or without analysis function), a lithography lens 105 (with or without focusing function). The exposed substrate 106 coated with a photosensitive material is also shown. The illumination module 102 includes, for example, two sets of light sources, one set is used for lithography exposure, the other set is used for focus plane detection, and the photosensitive material is not sensitive to the other set of light sources.

Fig. 5 is a schematic diagram of a use area of a spatial light modulator DMD chip in the DMD module 101. In the lithography system, in order to improve the exposure quality and efficiency, only a partial area (first area 101-1) in the height direction of the DMD is used, and the exposure light source illuminates only the area for pattern exposure. The second area 101-2 of the DMD module 101 writes a specific focal plane detection pattern, which may be, but is not limited to, a circle, a cross, a square, a grating, etc. in the drawing, in the second area 101-2.

The shaped light beams emitted by the two groups of light sources of the illumination module 102 irradiate on a chip of the DMD module 101, the exposure light source only illuminates a first area 101-1 for pattern exposure, and the focusing light source illuminates the whole area of the DMD or only the whole or partial second area 101-2. The image projected by the second region 101-2 is imaged onto the exposure substrate 106 through the optical lens 105, reflected by the exposure substrate 106 and imaged by the lithography lens 105, and returns to the spectroscopic mirror assembly 103, and the spectroscopic mirror assembly 103 reflects the light to the spectroscopic mirror assembly 103. The spectroscopic mirror group 103 collects an image, so that whether the position of the exposure substrate 106 is out of focus at this time can be judged by the quality of the collected image.

Because the detection pattern and the exposure pattern are generated in the same device (DMD module 101) and imaged through the same optical system, the detection of the focal plane is less affected by temperature and system errors, so that the detection of the focal plane is more stable and reliable. Meanwhile, the detection camera module 104 can also detect the output of the DMD image (101-1 area) in real time, so that complete closed-loop control is formed, and the reliability of the system is improved. Each area of the DMD module 101 can be interchanged and used, so that the service life of the device is effectively prolonged.

In fig. 4, the light splitting and reflecting module 103 and the detecting camera module 104 are adjusted to be below the lens 105 in the optical path to form a new detecting optical path, and at this time, an imaging lens needs to be arranged in the detecting camera module 104.

In the case of a microlens array, the maskless lithography system further includes a microlens array 107, a secondary imaging optical lens 108, a second dichroic mirror set 109, and a second focal plane detection camera module 110. The microlenses 107-2 on the microlens array 107 are optical structures in the lithography system that enhance lithographic minimum linewidth spacing.

The microlens array 107 is disposed on the image side of the lithography lens 105 or the beam splitting mirror group 103, and the light blocking layer 107-1 of the microlens array 107 is away from the exposure substrate 106.

The secondary imaging optical lens 108 and the second beam splitting mirror group 109 are disposed between the microlens array 107 and the exposure substrate 106 on the optical path, and the second focal plane detection camera module 110 receives the light beam emitted by the second beam splitting mirror group 109.

Preferably, a detection pattern 107-3 is etched on the surface of the light blocking layer of the microlens array 107. Light reflected by the light blocking layer of the microlens array reaches the focal plane detection camera module 104 after passing through the optical system, so that the focal plane condition of the upper imaging system is monitored.

In one embodiment, the light transmitted by the microlens array 107 passes through the secondary imaging optical lens 108 and then is projected to the second dichroic mirror set 109 (see fig. 6). In another embodiment, the light transmitted by the microlens array 107 passes through the second dichroic mirror set 109 before being projected to the secondary imaging optical lens 108.

Referring to the drawings, FIG. 6 is a schematic diagram of the optical path of an optical system with an MLA incorporating a detection camera. On the basis of fig. 3, a micro lens array 107, a secondary imaging optical lens 108, a second beam splitting mirror group 109 and a second focal plane detection camera module 110 are added. The light-splitting reflection module 103 and the focal plane detection camera module 104 in the dashed line frame are located on the optical path between the DMD module 101 and the lithography lens 105, and may also be moved to the optical path between the lithography lens 105 and the microlens array 107.

The optical information acquisition method of the focal plane detection camera module 104 is as follows: after imaging of the test pattern emitted from the DMD detection area, the microlens array 107 is reflected by the surface thereof to the focal plane detection camera module 104 through the spectral reflection module 103. The second focal plane detection camera module 110 detects the optical information acquisition path by: the detection pattern is imaged by a secondary imaging optical lens 108 (lower end optical lens) after passing through the microlens array 107, and the light reflected by the exposure substrate 106 is reflected by a second dichroic mirror group 109. The focal plane detection camera module 104 detects the focal point condition of the upper half optical path in real time, and the second focal plane detection camera module 110 monitors the focal point change condition of the lower end optical path in real time.

According to the embodiment of the invention, a focal plane detection camera is introduced into the optical path of the direct-write lithography system to perform real-time image plane focus detection. The installation position of the camera can be as shown in the light paths of fig. 3, 4 and 5, but is not limited to the positions identified in the figures, and can be set at any position of the main light path, such as the position a or the position B marked in fig. 6.

With respect to the detection pattern, it may be generated in any suitable manner. In a system without micro-lenses, a DMD free area (such as area 101-2 in FIG. 5) is used for converting a digital pattern into optical information required for detection; the digital graph can be designed into any shape according to the detection precision requirement, and is not limited to the graph sample illustrated in the graph; the graphic position may also be set to an arbitrary position of the area. In the optical system with the micro lens, in addition to generating the detection pattern by using the free area of the DMD, it is also possible to etch various shapes of detection-required patterns on the surface of the light-blocking layer of the micro lens as the object plane to be detected by the next optical system, such as the 107-3 position in fig. 9, but not limited to the position shown in the figure, and any pattern required for detection can be etched on the light-blocking layer at any position except the micro lens array.

The light source for focus detection may be the same wavelength or the same light source, or two or more different wavelengths according to the detection and exposure requirements. When the focusing wavelength is the same as the working wavelength, the working pattern and the detection pattern are focused on the exposure substrate 106 at the same time as shown in fig. 8a, and when the focusing wavelength is not the same as the working wavelength, there is a fixed difference between the exposure working image forming position and the detection pattern imaging position, the exposure image focus is at 106A, and the focusing wavelength imaging focal plane is at 106B of fig. 8B or 106C of fig. 8C. Because the difference is stable, the difference can be tested and fixed in advance, and therefore the measurement and the automatic focusing are not influenced by the three conditions.

In a system with MLA, the scanning operation is performed at the same wavelength as the detection focus system, with both focal planes at the same location, e.g., 107-4A in FIG. 10, and when different wavelengths are used, the detection focus path imaging focal plane will be at either 107-4C or 107-4B in FIG. 10.

Depending on the roughness of the surface of the exposed substrate 106, the surface 106 may be both specular and diffuse. In the case of specular reflection, the image of FIG. 6 is focused at the microlens 107 and exposes the surface of the substrate 106, respectively, as shown schematically in FIG. 7.

The embodiment of the invention also provides a real-time detection method for the image plane focus. In some embodiments, the image plane focus real-time detection method is implemented by using the device.

Specifically, the real-time image plane focus detection method comprises the following steps:

step S1, projecting a light source beam to the DMD module 101, wherein a first area 101-1 of the DMD module 101 reflects a first pattern for photoetching imaging, and a second area 101-2 of the DMD module 101 reflects a second pattern for image plane detection;

step S2, performing maskless lithography on the exposure substrate 106 coated with the photosensitive material, and simultaneously, the focal plane detection camera module 104 collects the image of the second pattern on the exposure substrate 106, wherein the light beam reflected by the DMD module 101 is projected to the exposure substrate 106 through the beam splitter mirror group 103 and the lithography lens 105 for maskless lithography, and then reflected back to the beam splitter mirror group 103 through the reflection of the exposure substrate 106, and the beam splitter mirror group 103 reflects the light to the focal plane detection camera module 104,

in step S3, the focal plane detection camera module 104 analyzes the quality of the image of the captured second pattern on the exposed substrate, and determines whether the position of the exposed substrate 106 is out of focus based on the analysis result.

In one embodiment of the present invention, step S2 further includes: the focal plane inspection camera module 104 captures an image of the first pattern on the exposed substrate 106, an

Step S3 further includes: the focal plane detection camera module 104 analyzes the quality of the image of the acquired first pattern on the exposed substrate, and determines whether to optimize the next or more subsequent first patterns to be projected based on the analysis result.

In a further alternative embodiment of the present invention, a microlens array 107, a secondary imaging optical lens 108, a second dichroic mirror set 109, and a second focal plane detection camera module 110 are provided. Microlenses are optical structures in a lithography system that increase the lithographic minimum linewidth spacing. Wherein the micro lens array 107 is disposed on the image side of the lithography lens 105 or the beam splitting mirror 103, and the light blocking layer of the micro lens array 107 is away from the exposure substrate 106,

the secondary imaging optical lens 108 and the second dichroic mirror group 109 are disposed between the microlens array 107 and the exposure substrate 106 on the optical path, the second focal plane detection camera module 110 receives the light beam emitted by the second dichroic mirror group 109, and the second focal plane detection camera module 110 determines whether the position of the exposure substrate 106 is out of focus according to the collected image quality.

Finally, it should be pointed out that: the above examples are only for illustrating the technical solutions of the present invention, and are not limited thereto. Those of ordinary skill in the art will understand that: modifications can be made to the technical solutions described in the foregoing embodiments, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A maskless lithography system, comprising:

a DMD module (101), wherein the DMD module (101) is provided with a first area (101-1) used for photoetching imaging and a second area (101-2) used for projecting an image surface detection pattern;

an illumination module (102) that projects a light beam to the first area (101-1) and the second area (101-2) of the DMD module (101);

the light beam reflected by the DMD module (101) is projected to an exposure substrate (106) coated with a photosensitive material through the light splitting reflector group (103) and the photoetching lens (105) and used for maskless photoetching, and is reflected back to the light splitting reflector group (103) through the exposure substrate (106), the light is reflected to the focal plane detection camera module (104) through the light splitting reflector group (103), and the focal plane detection camera module (104) judges whether the position of the exposure substrate (106) is out of focus at the moment through the collected image quality.

2. The maskless lithography system of claim 1, wherein the light reflected by said DMD module (101) passes through the lithography lens (105), then is projected to the beam splitter mirror group (103), then is projected to the exposure substrate (106), said maskless lithography system further comprising an optical path adjusting device, said optical path adjusting device being disposed between the beam splitter mirror group (103) and the focal plane detection camera module (104), such that the focal plane detection optical path and the maskless lithography optical path are imaged at the same focal plane position.

3. The maskless lithography system of claim 1, wherein the light reflected by said DMD module (101) passes through a beam splitting mirror assembly (103) and then is projected onto a lithography lens (105), wherein an imaging lens is disposed in said focal plane detection camera module (104).

4. The maskless lithography system of claim 1, wherein said illumination module (102) comprises an exposure light source for maskless lithography and a focus plane detection light source for focus plane detection,

the exposure light source and the focal plane detection light source are different light sources with different wavelengths, a photosensitive material coated on the exposure substrate (106) does not sense the focal plane detection light source, the exposure light source only illuminates a first area of the DMD module (101), and the focal plane detection light source only illuminates a second area of the DMD module (101); or

5. The maskless lithography system of claim 1, wherein said first area of said DMD module (101) and said second area of said DMD module (101) are periodically used interchangeably.

6. The maskless lithography system of any one of claims 1 to 5, further comprising a microlens array (107), a secondary imaging optical lens (108), a second beam splitting mirror set (109), a second focal plane detection camera module (110),

the micro lens array (107) is arranged on the image side of the photoetching lens (105) or the light splitting reflector group (103), and a light blocking layer (107-1) of the micro lens array (107) is deviated from the exposure substrate (106),

the secondary imaging optical lens (108) and the second beam splitting reflector group (109) are arranged between the micro lens array (107) and the exposure substrate (106) on an optical path, and the second focal plane detection camera module (110) receives light beams emitted by the second beam splitting reflector group (109).

7. The maskless lithography system of claim 6, wherein a detection pattern is etched on a light blocking layer surface of said microlens array (107).

8. The maskless lithography system of claim 7,

the light transmitted by the micro lens array (107) passes through a secondary imaging optical lens (108) and then is projected to a second beam splitting reflector group (109); and/or

The light transmitted by the micro lens array (107) passes through the second beam splitting reflector group (109) and then is projected to the secondary imaging optical lens (108).

9. An image plane focus real-time detection method is characterized by comprising the following steps:

step S1, projecting a light source beam to a DMD module (101), wherein a first area (101-1) of the DMD module (101) reflects a first pattern for photoetching imaging, and a second area (101-2) of the DMD module (101) reflects a second pattern for image plane detection;

step S2, performing maskless lithography on an exposure substrate (106) coated with a photosensitive material, and simultaneously acquiring the image of the second pattern on the exposure substrate (106) by a focal plane detection camera module (104), wherein the light beam reflected by the DMD module (101) is projected to the exposure substrate (106) through a beam splitting mirror group (103) and a lithography lens (105) for maskless lithography, and is reflected back to the beam splitting mirror group (103) through the reflection of the exposure substrate (106), and the beam splitting mirror group (103) reflects the light to the focal plane detection camera module (104),

in step S3, the focal plane detection camera module (104) analyzes the quality of the image of the captured second pattern on the exposed substrate, and determines whether the position of the exposed substrate (106) is out of focus based on the analysis result.

10. The image plane focus real-time detection method of claim 9,

step S2 further includes: a focal plane inspection camera module (104) captures an image of the first pattern on an exposed substrate (106), an

Step S3 further includes: the focal plane detection camera module (104) analyzes the image quality of the acquired first pattern imaged on the exposed substrate, and judges whether the next or more subsequent first patterns to be projected need to be optimized or not based on the analysis result.

11. The real-time image plane focus detection method of claim 9, wherein a micro-lens array (107), a secondary imaging optical lens (108), a second beam splitting mirror group (109), and a second focal plane detection camera module (110) are provided,

wherein the micro lens array (107) is arranged at the image side of the photoetching lens (105) or the light splitting reflector group (103), and a light blocking layer of the micro lens array (107) is deviated from the exposure substrate (106),

the secondary imaging optical lens (108) and the second beam splitting reflector group (109) are arranged between the micro lens array (107) and the exposure substrate (106) on a light path, the second focal plane detection camera module (110) receives light beams emitted by the second beam splitting reflector group (109), and the second focal plane detection camera module (110) judges whether the position of the exposure substrate (106) is out of focus or not according to the collected image quality.