CN102087483B - Optical system for focal plane detection in projection lithography - Google Patents
Optical system for focal plane detection in projection lithography Download PDFInfo
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- CN102087483B CN102087483B CN 201010605515 CN201010605515A CN102087483B CN 102087483 B CN102087483 B CN 102087483B CN 201010605515 CN201010605515 CN 201010605515 CN 201010605515 A CN201010605515 A CN 201010605515A CN 102087483 B CN102087483 B CN 102087483B
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Abstract
The invention relates to an optical system for focal plane detection in projection lithography. A focus detection mark and a projection imaging system are arranged between a lighting system and a multi-reflection prism; a plane to be detected is located between the multi-reflection prism and a reflector; a focus detection mark amplification system is located between the reflector and a detector; the projection imaging system is matched with the lighting system to provide a lighting beam for lighting the focus detection mark; the multi-reflection prism is used for splitting the incident beam of the lighting system for lighting the focus detection mark into two or more detection beams with different positions; the focus detection mark can mark the position and form an image of each detection beam on the surface of the plane to be detected through the projection imaging system and multi-reflection prism; the detection beams reflected by the plane to be detected is amplified by the focus detection mark amplification system and is incident to the detector; and the detector detects the position of the reflected images amplified by the optical amplification system so as to detect the focal plane position and the focal plane inclination of a lithographic projection objective lens.
Description
Technical field
The present invention relates to a kind of automatic focal plane system, is a kind of technology of the position movement of imaging surface being measured by the optical triangulation method.
Background technology
Lithographic equipment (litho machine) is one of visual plant of large scale integrated circuit production.Projection mask aligner can be imaged onto the figure on the mask plate by the imaging exposure device (such as silicon chip etc.) on the object that will process by a certain percentage, and silicon chip is made a general reference all here and is exposed object, comprises substrate, plated film and photoresist etc.In exposure process, the respective surfaces of processing object (such as silicon chip etc.) is remained within the focal depth range of exposure device.For this reason, projection mask aligner has adopted the focusing and leveling measuring system (focal plane system) of the surface position information that is used for measuring processing object (such as silicon chip etc.).Focusing and leveling measuring system can make with the machine table of clamping processing object (such as silicon chip etc.) zone that is exposed of processing object (such as silicon chip etc.) be within the depth of focus of projection mask aligner's exposure device together always, thereby figure on the mask plate is transferred on the processing object (such as silicon chip etc.) ideally.
Along with the figure section raising of projection mask aligner's resolution and constantly reducing of projection objective depth of focus, the measuring accuracy of the focusing and leveling of litho machine being measured subsystem is also more and more higher with the requirement that can measure in real time the performances such as exposure area.Therefore at present the focusing and leveling measuring system that adopts in the advanced scanning projecting photoetching machine is generally photoeletric measuring system, as: based on the photoelectric measurement method (US Patent No. 5191200) of grating and 4 quadrant detector, based on the photoelectric measurement method (US Patent No. 6765647B1) of slit and 4 quadrant detector, based on the photo-detection method of PSD (position sensitive detector) (Chinese patent: 200610117401) with based on the photo-detection method (Chinese patent: 200710171968) of optical grating Moire fringe.The measuring position of above-mentioned focusing and leveling measuring system is single position, namely can only test on the processing object certain a bit or average positional information in a certain tiny area.Measure two large functions for realizing focusing and leveling that projection mask aligner is required, need to adopt some cover focal plane (as: Overlay and field leveling in wafersteppers using an advanced metrology system of system, SPIE Vol.1673) adopt or in a system several marks (such as United States Patent (USP): US5191200), like this so that whole focusing and leveling measuring system is very redundant.
Summary of the invention
For solve an above-mentioned cover optical system only can carry out to certain a bit or a certain tiny area carry out focal plane, realize that the required focusing and leveling of projection mask aligner two large functions need to adopt some cover focal planes system, thereby the very redundant problem of whole focusing and leveling measuring system, the objective of the invention is to utilize a cover optical system to finish position of focal plane and tilt detection in the projection lithography, realize the function that focusing, leveling are measured.
For realizing purpose of the present invention, the invention provides the optical system for the projection lithography focal plane, the technical scheme that described optical system technical solution problem adopts comprises: illuminator, focusing test mark, projection imaging system, Multi reflection prism, detected face, catoptron, focusing test mark amplification system and sensitive detection parts; Focusing test mark and projection imaging system are between illuminator and Multi reflection prism, and detected face is between Multi reflection prism and catoptron, and focusing test mark amplification system is between catoptron and sensitive detection parts; Projection imaging system and illuminator coupling provide illumination light for illumination focusing test mark, the Multi reflection prism is divided into two bundles or the above detection light of two bundles with the incident light of the illumination focusing test mark of illuminator, and it is not identical that every bundle is surveyed the position of light, the mark that the focusing test mark is surveyed optical position by projection imaging system and Multi reflection prism with every bundle is imaged onto on the detected face surface, through the detection light after the detected face reflection, after amplifying, focusing test mark amplification system incides on the sensitive detection parts, utilize sensitive detection parts to survey reflected image position after optical amplification system amplifies, position of focal plane and the focal plane of photoetching projection objective lens tilted to detect.
Utilize described optical system for the projection lithography focal plane, can also be applied to other poor occasions of needs detection image-forming objective lens actual imaging face and desirable position of focal plane, be used for the image-forming objective lens focal plane and can also be applied to the occasion that needs Precision positioning.
Beneficial effect of the present invention: in the present invention, by introducing the Multi reflection prism, only adopt a cover optical system, position of focal plane detection and focal plane tilt detection have been realized simultaneously, not only reduce the system complex degree, also reduced error source, improved detection accuracy.The present invention just can realize the tilt detection of the face that is detected by the position sensing of a plurality of points.Because all detection light all is to be sent by same light source and same certification mark, so each surveys light strict conformance, and these survey light all by same optical system, therefore can eliminate the difference that optical system such as processed, debugs at the factor generation; Comprehensive above advantage, such structure arrangement can increase the precision that leveling and focusing is surveyed.
Description of drawings
Fig. 1 is projection mask aligner's schematic diagram.
Fig. 2 is the schematic diagram of the optical system of focal plane in the focal plane optical system projection mask aligner of the present invention among Fig. 1.
Fig. 3 is the Multi reflection schematic diagram.
Fig. 4 is for detecting the reflected light path synoptic diagram at detected face of light path.
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.
Fig. 1 shows the schematic diagram of projection mask aligner, leveling and focusing detection system 4a, processing object 5a and article carrying platform 6a that projection mask aligner contains optical axis 1a, mask plate 2a, photoetching projection objective lens 3a, is comprised of a plurality of focal plane optical systems.Mask plate 2a places the object plane of photoetching projection objective lens 3a, and processing object 5a (such as silicon chip etc.) places on the article carrying platform 6a.During photolithographic exposure, need movable object-carrying stage 6a so that the plane of exposure of processing object 5a is on the focal plane of photoetching projection objective lens 3a.For so that the image on the mask plate 2a be transferred to accurately on the processing object 5a, need to survey accurately and adjust the plane of exposure of processing object 5a and the relative position of photoetching projection objective lens 3a (comprising distance and inclination), so that the zone whole to be exposed of processing object 5a all is in the focal depth range of photoetching projection objective lens 3a.For reaching this purpose, just need to carry out precision to the position in the zone to be exposed on the processing object 5a by the leveling and focusing detection system 4a that a plurality of focal plane optical systems form and detect, and give the focusing and leveling executive system feedback of article carrying platform 6a.
Shown in Fig. 2 is improvement to focal plane optical system among Fig. 1, the optical system of focal plane is to utilize triangulation method in the projection mask aligner provided by the invention, optical system of the present invention comprises: illuminator 1, focusing test mark 2, projection imaging system 3, Multi reflection prism 4, detected face 5, catoptron 6, focusing test mark amplification system 7 and sensitive detection parts 8 form, focusing test mark 2 and projection imaging system 3 are between illuminator 1 and Multi reflection prism 4, detected face 5 is between Multi reflection prism 4 and catoptron 6, and focusing test mark amplification system 7 is between catoptron 6 and sensitive detection parts 8; Projection imaging system 3 provides illumination light with illuminator 1 coupling for illumination focusing test mark 2, Multi reflection prism 4 is divided into two bundles or the above detection light of two bundles with the incident light of the illumination focusing test mark 2 of illuminator 1, and it is not identical that every bundle is surveyed the position of light, the mark that focusing test mark 2 is surveyed optical position by projection imaging system 3 and Multi reflection prism 4 with every bundle is imaged onto on detected face 5 surfaces, through the detection light after detected face 5 reflections, after amplifying, focusing test mark amplification system 7 incides on the sensitive detection parts 8, utilize sensitive detection parts 8 to survey reflected image position after optical amplification system 7 amplifies, position of focal plane and the focal plane of photoetching projection objective lens 3a tilted to detect.
Illuminate focusing test mark 2 behind the light shaping that illuminator 1 is sent light source; Focusing test mark 2 is through being imaged on behind projection imaging system 3 and the Multi reflection prism 4 on the detected face 5; The upper surface of Multi reflection prism 4 has dichroism, and the lower surface of Multi reflection prism 4 has reflection characteristic, therefore after incident light reflects through Multi reflection prism 4, to form a reflection ray, be about to focusing test mark 2 and form a plurality of pictures with duplication characteristic, it is strict conformance that these pictures are not subjected to its shape of focusing test label creating technogenic influence and position relationship; The picture of focusing test mark 2 through the reflection of detected face 5 and catoptron 6 after by focusing test mark amplification system 7 amplification imagings on sensitive detection parts 8, the light signal that sensitive detection parts 8 obtain will be converted to electric signal, by corresponding Circuits System detection signal be read.The ideal image position of focal plane and the focusing plane detection system that obtain photoetching projection objective lens 3a by technological experiment are demarcated, and this focal plane system can Real-time Measuring after demarcating gets the alternate position spike of photoetching projection objective lens 3a actual imaging face and desirable focal plane.
Described illuminator 1 adopts broadband or monochromatic source, comprises light source commonly used in the engineerings such as Halogen lamp LED, xenon lamp, LED or laser instrument;
Described focusing test mark 2 is that the sensitive detection parts of being convenient to light and shade form detect mark, and wherein the mark of light and shade form is: spider, straight line, grating, round dot and circle a kind of.
The external reflection dielectric surface of described Multi reflection prism 4 is light splitting surface, need utilize the part reflection on reflecting medium surface or make it reach certain splitting ratio by methods such as plated films according to reality, Multi reflection prism 4 is divided into two bundle detection light or the above detection light of two bundles with the detection light of incident.The spectroscopic property of the reflective outer surface of described Multi reflection prism 4 can be the color separation light splitting, also can be neutral light splitting.Described Multi reflection prism 4 can be parallel light through the outside surface chief ray that reflects and the chief ray that reflects through outside surface again through internal surface reflection, also can be light at angle.
Described detected face 5 is the plane with mirror-reflection, diffuse reflection or scattering nature, the curved surfaces that are positioned at photoetching projection objective lens 1a image planes.
Described sensitive detection parts 8 are to be not limited to CCD planar array detector 8, can also be cmos device, two quadrant detectors, 4 quadrant detector, position sensor (PSD) and a kind of in the photodetection class device of light signal sensitivity.
As shown in Figure 3, after light incides Multi reflection prism 4, the front surface reflection of part light by Multi reflection prism 4, the front surface of part light transmission Multi reflection prism 4 and by the rear surface reflection of Multi reflection prism 4 again through the front surface outgoing.If transmitance and the reflectivity of appropriate design Multi reflection prism 4 front and rear surfaces then can make incident light be divided into two bundles or the above light of two bundles.These light send by same light source and same focusing test mark 2, have strict copy feature.
As shown in Figure 4, the detection light that is gone out by 3 projections of focusing test mark projection imaging system by focusing test mark 2 be divided into two bundles or two bundles above after, incide respectively on the detected face 5.These survey the skew that the light along continuous straight runs has X, that is to say that also there is the skew of X the location to be detected, by the position sensing of a plurality of points, just can realize the tilt detection of detected face.Because all detection light all is to be sent by same light source and same focusing test mark 2, so each surveys the light strict conformance; And these survey light all by same optical system, therefore can eliminate the difference that optical system such as processed, debugs at the factor generation; Comprehensive above advantage, such structure arrangement can increase the precision that leveling and focusing is surveyed.
Above-mentioned the drawings and specific embodiments only are one embodiment of the invention, are not deviating under the invention scope prerequisite that invention spirit of the present invention and claims define, and the present invention can have and variously augments, revises and substitute.Therefore, above-described embodiment is for explanation illustration the present invention but not limit the scope of the invention, and have the right requirement and legal equivalents thereof of scope of the present invention defines, and is not limited to description before this.Claims are intended to contain all these type of coordinators.
Claims (8)
1. an optical system that is used for the projection lithography focal plane is characterized in that: be comprised of illuminator (1), focusing test mark (2), projection imaging system (3), Multi reflection prism (4), detected face (5), catoptron (6), focusing test mark amplification system (7) and sensitive detection parts (8); Focusing test mark (2) and projection imaging system (3) are positioned between illuminator (1) and the Multi reflection prism (4), detected face (5) is positioned between Multi reflection prism (4) and the catoptron (6), and focusing test mark amplification system (7) is positioned between catoptron (6) and the sensitive detection parts (8); Projection imaging system (3) provides illumination light with illuminator (1) coupling for illumination focusing test mark (2), Multi reflection prism (4) is divided into two bundles or the above detection light of two bundles with the incident light of the illumination focusing test mark (2) of illuminator (1), and it is not identical that every bundle is surveyed the position of light, the mark that focusing test mark (2) is surveyed optical position by projection imaging system (3) and Multi reflection prism (4) with every bundle is imaged onto on detected face (5) surface, through the detection light after detected face (5) reflection, after amplifying, focusing test mark amplification system (7) incides on the sensitive detection parts (8), utilize sensitive detection parts (8) to survey reflected image position after focusing test mark amplification system (7) is amplified, position of focal plane and the focal plane of photoetching projection objective lens (3a) tilted to detect; The reflective outer surface of described Multi reflection prism (4) is light splitting surface, described light splitting surface is to utilize the part reflection on reflecting medium surface or make light splitting surface reach the splitting ratio of setting by film plating process, and Multi reflection prism (4) is divided into two bundles or the above detection light of two bundles with the detection light of incident.
2. the optical system for the projection lithography focal plane according to claim 1 is characterized in that: described illuminator (1) adopts broadband or monochromatic source, and described broadband or monochromatic source comprise Halogen lamp LED, xenon lamp, LED or laser instrument.
3. the optical system for the projection lithography focal plane according to claim 1, it is characterized in that: described focusing test mark (2) has the mark that sensitive detection parts are surveyed of being convenient to of light and shade form, and wherein the mark of light and shade form is a kind of in spider, straight line, grating, round dot and the circle.
4. the optical system for the projection lithography focal plane according to claim 1 is characterized in that: the spectroscopic property of the reflective outer surface of described Multi reflection prism (4) can be the color separation light splitting, also can be neutral light splitting.
5. the optical system for the projection lithography focal plane according to claim 1, it is characterized in that: described Multi reflection prism (4) can be parallel light through the outside surface chief ray that reflects and the chief ray that reflects through outside surface again through internal surface reflection, also can be light at angle.
6. the optical system for the projection lithography focal plane according to claim 1, it is characterized in that: described detected face (5) is the plane with mirror-reflection, diffuse reflection or scattering nature, the curved surface that is positioned at photoetching projection objective lens (3a) image planes.
7. the optical system for the projection lithography focal plane according to claim 1, it is characterized in that: described sensitive detection parts (8) are not limited to the CCD planar array detector, can also be a kind of in cmos device, two quadrant detectors, the 4 quadrant detector.
8. utilize the optical system for the projection lithography focal plane claimed in claim 1, can also be applied to other poor occasions of needs detection image-forming objective lens actual imaging face and desirable position of focal plane, be used for the image-forming objective lens focal plane and can also be applied to the occasion that needs Precision positioning.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201010605515 CN102087483B (en) | 2010-12-27 | 2010-12-27 | Optical system for focal plane detection in projection lithography |
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| CN 201010605515 CN102087483B (en) | 2010-12-27 | 2010-12-27 | Optical system for focal plane detection in projection lithography |
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| CN102087483B true CN102087483B (en) | 2013-04-03 |
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Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102236270B (en) * | 2011-07-29 | 2012-12-19 | 中国科学院光电技术研究所 | Focus detection device applicable to double workpiece table projection lithography machine |
| CN102243138A (en) * | 2011-08-05 | 2011-11-16 | 中国科学院光电技术研究所 | Focal plane detection device for projection lithography |
| CN103744269B (en) * | 2014-01-03 | 2015-07-29 | 中国科学院上海光学精密机械研究所 | The detection method of wave aberration of photoetching projection objective and imaging optimal focal plane |
| CN105807579B (en) * | 2014-12-31 | 2018-10-16 | 上海微电子装备（集团）股份有限公司 | A kind of silicon chip and substrate prealignment measuring device and method |
| CN105807570B (en) * | 2014-12-31 | 2018-03-02 | 上海微电子装备（集团）股份有限公司 | The focusing leveling device and its method of adaptive groove |
| CN107450287B (en) * | 2016-05-31 | 2019-10-25 | 上海微电子装备（集团）股份有限公司 | Focusing and leveling measurement apparatus and method |
| JP7137363B2 (en) * | 2018-06-11 | 2022-09-14 | キヤノン株式会社 | Exposure method, exposure apparatus, article manufacturing method and measurement method |
| CN109443210A (en) * | 2018-12-13 | 2019-03-08 | 苏州亿拓光电科技有限公司 | Optical position detection device and method |
| CN112846485B (en) * | 2020-12-31 | 2022-11-04 | 武汉华工激光工程有限责任公司 | Laser processing monitoring method and device and laser processing equipment |
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| CN2352976Y (en) * | 1998-09-03 | 1999-12-08 | 中国科学院光电技术研究所 | Focusing device for sumillimeter photoetching machine |
| CN101201546A (en) * | 2007-11-28 | 2008-06-18 | 上海微电子装备有限公司 | Device for automatically focusing and leveling |
| CN101403866A (en) * | 2008-11-18 | 2009-04-08 | 上海微电子装备有限公司 | Object position measurement apparatus and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH097915A (en) * | 1995-06-15 | 1997-01-10 | Nikon Corp | Surface tilt detection system |
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Patent Citations (3)
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| CN2352976Y (en) * | 1998-09-03 | 1999-12-08 | 中国科学院光电技术研究所 | Focusing device for sumillimeter photoetching machine |
| CN101201546A (en) * | 2007-11-28 | 2008-06-18 | 上海微电子装备有限公司 | Device for automatically focusing and leveling |
| CN101403866A (en) * | 2008-11-18 | 2009-04-08 | 上海微电子装备有限公司 | Object position measurement apparatus and method |
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